CN101875739B - Molded product of a polypropylene-based resin expanded particle and method for producing the same - Google Patents

Molded product of a polypropylene-based resin expanded particle and method for producing the same Download PDF

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CN101875739B
CN101875739B CN200911000170.5A CN200911000170A CN101875739B CN 101875739 B CN101875739 B CN 101875739B CN 200911000170 A CN200911000170 A CN 200911000170A CN 101875739 B CN101875739 B CN 101875739B
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expanded particle
peak
polypropylene
endotherm
formed body
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CN101875739A (en
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及川政春
筱原充
野原德修
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JSP Corp
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JSP Corp
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Abstract

The invention relates to a molded product of a polypropylene-based resin expanded particle and a method for producing the same. The object of the invention is to provide a molded product of a polypropylene-based resin expanded particle with a low expansion ratio having excellent fusibility between expanded particles mutually, small density difference between a surface part and an inner part of the molded product, better mechanical properties, such as compressive strength, compared with a conventional one, and also excellent appearance. In an in-mold molding method with the polypropylene-based resin expanded particle, the expanded particle has apparent density of 60-450 g/L, the welding rate of the polypropylene-based resin expanded particle is above 50%, the ratio between the apparent density of the expanded particle molded body to the inner density of the molded body is 1-2 and the molded product of the polypropylene-based resin expanded particle is preferably molded when satisfying the special conditions.

Description

Polypropylene-based resin expanded particle formed body and manufacture method thereof
Technical field
The present invention relates to a kind of polypropylene-based resin expanded particle formed body and manufacture method thereof, the particularly skin section of expanded particle formed body and the inner little high density poly propylene resin expanded particle formed body of density difference, and highdensity polypropylene-based resin expanded particle is being carried out when in-molded, obtain the manufacture method of the expanded particle formed body of expanded particle formed body under can the mold temperature low in the in-molded temperature than in the past.
Background technology
Acrylic resin, because it has the character that physical strength, thermotolerance, processibility, burning, reproducibility etc. are excellent, so Application Areas constantly expands.Equally, polypropylene-based resin expanded particle is carried out to the in-molded polypropylene-based resin expanded particle formed body forming, can not lose the excellent properties of above-mentioned acrylic resin, in addition the characteristics such as its resiliency, thermal insulation, light weight be can also give, wrapping material, material of construction or impact absorption material for use with vehicle etc. are therefore widely used in.In addition, for the packaging pallet of electronic unit, automotive light weight technology parts etc., need accurate dimensional precision and high strength, therefore envision high-density, the i.e. increase in demand of the polypropylene-based resin expanded particle formed body of low expansion ratio.
Highdensity polypropylene-based resin expanded particle formed body, can be by carrying out in-molded obtaining to the large expanded particle of apparent density.But in this is in-molded, the polypropylene-based resin expanded particle large due to apparent density carries out second time of foaming, meanwhile, the surface of expanded particle fuses mutually, therefore, only makes expanded particle melt surface have difficulties.
In the prior art, the deviation that reduces the apparent density of polypropylene-based resin expanded particle by use has regulated the expanded particle of average bubble number, thereby improve the second time of foaming of expanded particle, the mutual fusion character (melting adhesivity) on expanded particle surface, the method (patent documentation 1) of the expanded particle formed body of manufacture outward appearance and excellent rigidity is just in practical application.
But, to density, be more than 60 (g/L), when particularly the above high density poly propylene resin expanded particle formed body of 100 (g/L) carries out moulding, for obtaining the low range expanded particle of this expanded particle formed body, compare with powerful expanded particle, when in-molded, the mutual fusion character of expanded particle easily reduces.Thus, even make by the Heating temperature improving when in-molded the expanded particle second time of foaming that formed body appearance is good, it is not enough that the inside fusion character of this expanded particle formed body also easily becomes.Therefore, in order to obtain the sufficient expanded particle formed body of this fusion character, the filling rate of compression in the time of need to taking measures to improve expanded particle and be filled in mould, and further improve as the water vapor pressure of the saturated steam of heating medium etc.
Therefore in this case, if improve this water vapor pressure, Heating temperature also becomes higher, has cooling time when in-molded elongated, the problem that productivity declines.In addition, expanded particle formed body due to gained, the saturated steam that uses high water vapor to press carries out in-molded, therefore, there is the bubble of expanded particle formed body skin section to break and densification, the inside of gained expanded particle formed body and skin section produce density difference, and compress the problem of the physical strength deficiencies such as physical property.
[patent documentation 1] TOHKEMY 2000-63556 communique
Summary of the invention
The object of the invention is to provide the mutual fusion character of a kind of expanded particle excellent, the skin section of expanded particle formed body and inner density difference are little, and the mechanical properties such as compressive strength and outward appearance are all than the polypropylene resin foam particle formed body of in the past excellent low expansion ratio.
In addition, the object of the invention is to provide a kind of toughness as polypropylene-based resin expanded particle formed body feature, thermotolerance, easy excellent properties of reproducibility etc. can not damaged, in-molded by carrying out under the Heating temperature than in the past low, thus the manufacture method of the polypropylene-based resin expanded particle formed body of the low expansion ratio with excellent physical property stably manufactured.
The object of the invention is to develop a kind of polypropylene-based resin expanded particle, its can the mold temperature low at the mold temperature of the polypropylene-based resin expanded particle than in the past under, in the situation that do not damage the characteristic that polypropylene-based resin expanded particle formed body has in the past, obtain the also expanded particle formed body of excellent low range of the mechanical properties such as the mutual fusion character excellence of expanded particle, compressive strength.In order to realize this object, applicant is to the relation between the crystal structure of expanded particle and the mechanical properties of expanded particle formed body, relation between the behavior when in-molded of the crystal structure of expanded particle and expanded particle, and in-molded method etc. is studied, found that, by making the in-molded mold temperature scope of carrying out of expanded particle, to low temperature side, expand, in addition, rate of compression while regulating expanded particle to fill in mould therefor when in-molded, can stably obtain having the expanded particle formed body of the low expansion ratio of excellent physical property, and complete thus the present invention.
That is to say, the invention that the present invention be take following (1) and (2) are recorded is main points.
(1) a polypropylene-based resin expanded particle formed body, it is that polypropylene-based resin expanded particle is filled in mould and carries out the expanded particle formed body that hot briquetting forms, it is characterized in that,
The density of this expanded particle formed body is 60g/L～450g/L, and the fusion rate (melting rate) of polypropylene-based resin expanded particle is more than 50%, and the skin section density of this expanded particle formed body is 1～2 divided by the density ratio of the internal density gained of this formed body,
The polypropylene-based resin expanded particle that forms this expanded particle formed body is characterised in that at least one meeting in following condition 1～condition 3,
Condition 1: there is following crystal structure,, at heat flux means of differential scanning calorimetry, measure in (Hot a fluid stream differential Walkthrough Hot Liang Measuring is fixed), with the heat-up rates of 2 ℃/min, polypropylene-based resin expanded particle is heated to a DSC curve of 200 ℃ of gained from normal temperature, appearance is the main endotherm(ic)peak of 100 ℃～140 ℃ with respect to the endotherm(ic)peak heat of total endotherm(ic)peak heat demonstration 70%～95% and the summit temperature of endotherm(ic)peak, and the crystal structure that is positioned at 2 above endotherm(ic)peaks of this main endotherm(ic)peak high temperature side;
Condition 2: polypropylene-based resin expanded particle using low melting point acrylic resin that 80～98 weight part fusing points are 100 ℃～140 ℃ and 20～2 weight part fusing points than the mixture of the high more than 20 ℃ high-melting-point acrylic resin of this low melting point acrylic resin as substrate resin;
Condition 3: in heat flux means of differential scanning calorimetry is measured, with the heat-up rates of 10 ℃/min, polypropylene-based resin expanded particle is heated to 200 ℃ from normal temperature, with the cooling rates of 10 ℃/min, be cooled to 30 ℃, and then be heated in the 2nd DSC curve of 200 ℃ of gained with the heat-up rate of 10 ℃/min, from 80 ℃ to being 0.55～0.80 than the melting heat of the temperature of low 5 ℃ of the fusing point of this polypropylene-based resin expanded particle divided by the heat ratio of total endotherm(ic)peak heat gained.
(2) manufacture method for polypropylene-based resin expanded particle formed body, it is polypropylene-based resin expanded particle to be filled in to the manufacture method of the expanded particle formed body that carries out hot briquetting in mould,
The apparent density of this polypropylene-based resin expanded particle is 100g/L～720g/L, and meanwhile, it meets at least one in above-mentioned condition 1～condition 3, and the rate of compression of this polypropylene-based resin expanded particle while filling in mould is 0～15%.
Polypropylene-based resin expanded particle formed body of the present invention, when it is characterized in that expansion ratio is low, the skin section of expanded particle formed body and inner density difference are less than in the past, and therefore, due to this epoch-making feature, its compressive strength is also excellent.
In addition, expanded particle formed body of the present invention, the fusion character mutual due to expanded particle is good, so other mechanical properties is also excellent.Further, in its surface, the gap that is called space (viod) between venting hole mark, expanded particle is little for this expanded particle formed body, and smoothness is excellent, and outward appearance is good.
According to the manufacture method of polypropylene-based resin expanded particle formed body of the present invention, it can be in temperature under the in-molded heating condition lower than prior art, form the low expansion ratio expanded particle formed body of the mutual fusion character excellence of expanded particle, therefore, can shorten cooling time after heating when in-molded, and shorten thus the in-molded time.
In addition, manufacturing method according to the invention, in in-molded, do not need the saturated steam of pressing by excess steam to heat, therefore, can reduce the mold pressure of forming machine, more than not needing that the weather resistance of mould is increased to necessary degree, can reduce the thickness of mould, very large in manufacturing cost and the advantage aspect weather resistance of forming machine and mould, in-molded comparing in the past, can significantly cut down cost of energy.
In addition, manufacturing method according to the invention, can obtain comparing with expanded particle formed body in the past, and fusion rate is high, and expanded particle formed body skin section and inner density ratio are little, and also excellent polypropylene-based resin expanded particle formed body of compression physical property.
Accompanying drawing explanation
[Fig. 1] is illustrated in the manufacture method of expanded particle formed body of the present invention, a DSC curve shows figure of polypropylene-based resin expanded particle.
[Fig. 2] is illustrated in the manufacture method of expanded particle formed body of the present invention, the 2nd DSC curve shows figure of polypropylene-based resin expanded particle.
Nomenclature
On α DSC curve, be equivalent to the point of 80 ℃
The point that is equivalent to melting end temp on β DSC curve
The paddy portion at γ low temperature side peak and high temperature side peak
The intersection point of δ straight line alpha-beta and the vertical line that draws from γ
Te melting end temp
A 1main endotherm(ic)peak
A 2the endotherm(ic)peak of main endotherm(ic)peak high temperature side
A 3the endotherm(ic)peak of main endotherm(ic)peak high temperature side
TmA, PTmA endotherm(ic)peak summit temperature
The main endotherm(ic)peak heat of Δ Ha
Δ Hb endotherm(ic)peak a 2endotherm(ic)peak heat
Δ Hc endotherm(ic)peak a 3endotherm(ic)peak heat
Embodiment
Below, the manufacture method of (1) polypropylene-based resin expanded particle using in the present invention, (2) polypropylene-based resin expanded particle formed body and (3) polypropylene-based resin expanded particle formed body are described.
(1) polypropylene-based resin expanded particle
As expanded particle used in in-molded, there is following expanded particle: have by foamable particle, first form the state that expanded particle can fuse mutually, then the expanded particle of character that forms the state that expanded particle can second time of foaming is (following, the expanded particle with this character is called to fusion and preferentially carries out type expanded particle), with have by foamable particle, first form the state that expanded particle can second time of foaming, then the expanded particle that forms the character of the state that expanded particle can fuse is mutually (following, the expanded particle with this character is called to second time of foaming and preferentially carries out type expanded particle).In research of the present invention, obtained a kind of like this viewpoint, that is, under the Heating temperature than in the past low, expanded particle to be carried out when in-molded, fusion is preferentially carried out type expanded particle and is carried out type expanded particle more preferably than second time of foaming is preferential.
Above-mentioned when in-molded, fusion is preferentially carried out type expanded particle and is carried out than second time of foaming is preferential the reason that type expanded particle is more preferably used, as described below.
If use second time of foaming preferentially to carry out type expanded particle when in-molded, in the heating process when in-molded, because the second time of foaming of expanded particle preferentially carries out, therefore the expanded particle gap being filled in mould is easily crowded with, easily hinder water vapour to flow into, pass through the gap between expanded particle, result has hindered the mutual fusion of expanded particle.
And fusion is preferentially carried out type expanded particle and be difficult to be produced the principal element that second time of foaming preferentially carries out the above-mentioned obstruction that type expanded particle reflects.In addition, no matter be to fuse preferentially to carry out type expanded particle, or second time of foaming preferentially carries out type expanded particle, only otherwise use the resin that fusing point difference is large to cover the special operations such as expanded particle surface, the mutual fusion temperature of expanded particle and second time of foaming temperature just do not have the larger temperature head shown in aftermentioned embodiment and comparative example.
By using this expanded particle, can under the Heating temperature than in the past low, carry out in-molded, can also obtain the mutual fusion character of expanded particle excellent, the skin section of expanded particle formed body and inner density difference are little, and also excellent expanded particle formed body of mechanical properties, outward appearance.
Type polypropylene-based resin expanded particle is preferentially carried out in fusion in the present invention, can distinguish by following operation.
By stacking volume (Song Ti Plot) be about 100cm 3polypropylene-based resin expanded particle to put into volume be 5L (liter) and have in the pressure vessel of pressure regulator valve, then, use is equivalent to the saturated steam of the melt temperature of this polypropylene-based resin expanded particle, heats the operation in 10 seconds of this expanded particle.The apparent density of the polypropylene-based resin expanded particle after the heating based on by this operation gained, with the apparent density of polypropylene-based resin expanded particle before the heating of putting in pressure vessel, if the apparent density of the apparent density gained of the polypropylene-based resin expanded particle after divided by heating is than (ρ by the apparent density of the polypropylene-based resin expanded particle before heating r) greatly about 1.0～1.7 scope, the polypropylene-based resin expanded particle of putting in pressure vessel is to fuse preferentially to carry out type polypropylene-based resin expanded particle.
In fusion, preferentially carry out, in type expanded particle, preferably when in-molded, having suitable second time of foaming power, therefore above-mentioned apparent density is than (ρ r) more preferably 1.1～1.6, and more preferably 1.2～1.5.
In addition, in the present invention, the above-mentioned melt temperature of expanded particle, to use heat flux means of differential scanning calorimetry determinator (hereinafter referred to as DSC device) and measure the value of gained according to " carrying out after certain thermal treatment, measure the situation of melt temperature " method of recording in JIS K7121 (1987).Specifically, this melt temperature, using 1～3mg polypropylene-based resin expanded particle as sample, and according to heat flux means of differential scanning calorimetry assay method (hereinafter referred to as DSC), with 10 (℃/min) heat-up rate it is warming up to 200 ℃ from normal temperature, with 10 (℃/min) speed be cooled to 30 ℃, and then with 10 (℃/min) heat-up rate it is warming up to 200 ℃ from 30 ℃, by the means of differential scanning calorimetry of gained at this moment, measured the summit temperature of the determined endotherm(ic)peak of curve (DSC curve).In addition, while having a plurality of endotherm(ic)peak in DSC curve, using the summit temperature of the endotherm(ic)peak of maximum area as melt temperature.
In addition, above-mentioned apparent density is than (ρ r) detailed determination step, as described below.
Stacking volume is about to 100cm 3the known expanded particle (expanded particle before heating) of apparent density join in 5L (liter) pressure vessel with pressure regulator valve, use is equivalent to the saturated steam of the water vapor pressure of expanded particle melt temperature, in this airtight container, this expanded particle is heated to 10 seconds, the expanded particle after being heated thus.
In addition, the apparent density of the expanded particle before heating, be by expanded particle under normal pressure, temperature is to place and carry out above after status adjustment in 48 hours under 23 ℃, the relative humidity condition that is 50%, this expanded particle group that use wire netting etc. is W (g) by weight sinks in the graduated cylinder that adds water, by water level ascending amount, obtained this expanded particle group's volume: V (L), and the value of obtaining divided by this expanded particle group's volume (W/V) by this expanded particle group's weight.
In addition, the apparent density of the expanded particle after heating, be by above-mentioned pressure vessel, heat 10 second gained expanded particle under normal pressure, temperature is to place and carry out above after status adjustment in 48 hours under 23 ℃, the relative humidity condition that is 50%, this expanded particle group that use wire netting etc. is W (g) by weight sinks in the graduated cylinder that adds water, by water level ascending amount, obtained this expanded particle group's volume: V (L), and the value of obtaining divided by this expanded particle group's volume (W/V) by this expanded particle group's weight.
Polypropylene-based resin expanded particle of the present invention has the apparent density of 100～720 (g/L).The upper limit of the apparent density of this expanded particle, considers to determine according to the angle of the fundamental characteristics such as the light weight of raising gained expanded particle formed body, resiliency, is preferably 500 (g/L), more preferably 300 (g/L).On the other hand, if the apparent density of expanded particle is too low, be difficult to obtain object expanded particle formed body of the present invention, so the lower limit of apparent density is preferably 120 (g/L), more preferably 150 (g/L).
In addition, the apparent density of above-mentioned expanded particle, within having added the graduated cylinder of water, use wire netting etc. sinks to weight for the expanded particle group of W (g), by water level ascending amount, obtained this expanded particle group's volume: V (L), and the value of obtaining divided by this expanded particle group's volume (W/V) by this expanded particle group's weight.
Obtain the method for this polypropylene-based resin expanded particle, be documented in " (1-5) manufacture method of polypropylene-based resin expanded particle " item.
Form the substrate resin of polypropylene-based resin expanded particle of the present invention, as long as can meet structure condition of the present invention, no matter it is that alfon, propylene-based block copolymer or propylene are random copolymers, can use.In addition, as aforesaid propylene multipolymer, comprise propylene and ethene and/or carbonatoms and be the multipolymer of 4～20 alpha-olefin, can enumerate the multipolymer of propylene and ethene, 1-butylene, 1-amylene, 1-hexene, 1-octene, 4-methyl isophthalic acid-butylene etc.Aforesaid propylene multipolymer, can be the copolymers such as propylene-ethylene random copolymers, propene-1-butene random copolymers, can be also the terpolymers such as propylene-ethylene-butene random copolymers.In addition, polypropylene copolymer preferably in this multipolymer from the structural unit content of propylene be 70 % by weight above, be further 80～99.5 % by weight, the structural unit content of the alpha-olefin gained that is 4～20 by ethene and/or carbonatoms is the acrylic resin that 30 % by weight are following, be preferably 0.5～20 % by weight.
By making expanded particle of the present invention, be that type polypropylene-based resin expanded particle is preferentially carried out in above-mentioned fusion, under can the mold temperature that in-molded temperature is low at the polypropylene-based resin expanded particle than in the past, carry out in-molded, simultaneously, by this expanded particle when in-molded, can stably obtain outward appearance, the mutual excellent expanded particle formed bodys such as fusion character of expanded particle.In addition,, by making this expanded particle meet aforementioned apparent density, can obtain the expanded particle formed body of excellent rigidity.
Type polypropylene-based resin expanded particle is preferentially carried out in above-mentioned fusion, such as can by regulate expanded particle crystal structure method, the method for the separated foam rate that regulates expanded particle, bubble diameter, epidermal area thickness etc. obtain.
It is at least one the expanded particle that meets condition 1～condition 3 defined, following record in the present invention that type polypropylene-based resin expanded particle is preferentially carried out in fusion of the present invention.
(1-1) satisfy condition 1 polypropylene-based resin expanded particle (P1)
The condition 1 of polypropylene-based resin expanded particle given to this invention, to there is following crystal structure,, in DSC measures, use DSC device with 2 (℃/min) heat-up rate by a DSC curve of 1～3mg expanded particle gained when normal temperature (general 25 ℃) is heated to 200 ℃, appearance is the main endotherm(ic)peak of 100 ℃～140 ℃ with respect to the endotherm(ic)peak heat of total endotherm(ic)peak heat demonstration 70%～95% and the summit temperature of endotherm(ic)peak, and the crystal structure that is positioned at 2 above endotherm(ic)peaks of this main endotherm(ic)peak high temperature side.
Be noted that, in the DSC of expanded particle measures, with respect to employing be generally 10 (℃/min) heat-up rate, and adopt 2 (℃/min) the reason of heat-up rate, owing to having or not the peculiar crystal structure of expanded particle in order to identify,, whether expanded particle has the specific crystal structure that occurs more than 3 endotherm(ic)peak in a DSC curve, need to be than the slow down rate of heating condition of DSC of normal conditions, and according to different types of crystal, improve the resolving power of endotherm(ic)peak and measure, therefore, applicable heat-up rate be 2 (℃/min).
As the satisfy condition acrylic resin of substrate resin of 1 expanded particle (P1) of formation, as long as satisfy condition 1, can comprise single resin, also can comprise hybrid resin, this is not particularly limited.
As this single resin, can enumerate and use metallocene catalyst to carry out the acrylic resin etc. of multistage polymerization (multistage coincidence) gained.In addition,, as this hybrid resin, can enumerate the mixture of the acrylic resin of above-mentioned multistage polymerization gained and the mixture of other acrylic resin, low melting point acrylic resin and high-melting-point acrylic resin etc.In addition, for substrate resin, no matter single resin or hybrid resin, the viewpoint of the expanded particle with above-mentioned specific crystal structure of being easy to get to is calmly considered, all preferably uses and adopts metallocene Type of Collective catalyzer to carry out the acrylic resin of polymerization gained.
In condition 1, aforementioned main endotherm(ic)peak comes from the watery fusion composition in the resin that forms expanded particle (P1).On the other hand, be arranged in the high-temperature fusion composition that 2 of this main endotherm(ic)peak high temperature side above endotherm(ic)peaks come from the resin that forms expanded particle (P1).
When the substrate resin of expanded particle (P1) comprises single resin, formed low melting point polypropylene composition when this main endotherm(ic)peak comes from as the acrylic resin polymerization of substrate resin, formed high-melting-point polypropylene composition when being positioned at 2 of this main endotherm(ic)peak high temperature side above endotherm(ic)peaks and coming from this acrylic resin polymerization, or the high-melting-point composition that generates of this composition and the isothermal crystalization operation (for isothermal crystal operation etc., describe hereinafter) that forms the low melting point polypropylene composition of aforementioned main endotherm(ic)peak.
In addition, when the substrate resin of expanded particle (P1) comprises hybrid resin, this main endotherm(ic)peak comes from the low melting point acrylic resin (P1a) that forms hybrid resin, 2 above endotherm(ic)peaks that are positioned at this main endotherm(ic)peak high temperature side come from other more dystectic acrylic resin (P1b), or the high-melting-point composition that generates of this dystectic acrylic resin (P1b) and the isothermal crystalization operation (for isothermal crystal operation etc., describe hereinafter) that forms the low melting point acrylic resin (P1a) of aforementioned main endotherm(ic)peak.
In addition, because the summit temperature of main endotherm(ic)peak approaches the melting point resin as the acrylic resin of the substrate resin of expanded particle (P1), therefore above-mentioned with 2 (℃/min) a DSC curve of heat-up rate gained in, the summit temperature that occurs endotherm(ic)peak is the situation of the main endotherm(ic)peak of 100～140 ℃ of temperature ranges, when substrate resin is single resin, represent the polypropylene composition that principal constituent is low melting point, when substrate resin is hybrid resin, represent the acrylic resin that principal constituent is low melting point.
This expanded particle (P1), shows aforementioned distinctive DSC curve, due to the existence of this main endotherm(ic)peak, can reduce the fusion temperature of expanded particle when in-molded.In addition, the existence of 2 of this main endotherm(ic)peak high temperature side above endotherm(ic)peaks, have played the effect that limits expanded particle second time of foaming when in-molded.Therefore, this expanded particle (P1) preferentially carries out type expanded particle for fusion, and the in-molded temperature range of expanded particle is expanded to low temperature side, and in addition, when in-molded, the mutual fusion character of expanded particle has also improved.
The expanded particle (P1) that meets above-mentioned condition 1 is to have by above-mentioned DSC, to measure the expanded particle of the specific crystal structure of confirming, this detailed confirmation method is recorded in below.
Use DSC device with 2 (℃/min) the explanatory view of heat-up rate representational DSC curve of gained when 1～3mg expanded particle is heated to 200 ℃ from normal temperature be shown in Fig. 1.In the DSC of Fig. 1 curve, a 1, a 2, a 3represent respectively endotherm(ic)peak.In addition, total endotherm(ic)peak heat (Δ H) of an above-mentioned DSC curve, can obtain as follows.
As shown in Figure 1, connect on aforementioned DSC curve corresponding to the some α of 80 ℃ with corresponding to the some β on the DSC curve of resin melting end temp Te, draw straight line (alpha-beta), using it as baseline, and using be equivalent to this baseline and DSC Curves surround part area heat as total endotherm(ic)peak heat (Δ H) (J/g).The heat at above-mentioned peak, is used the calculation of DSC device and automatically calculates based on peak area.In addition, total endotherm(ic)peak heat (Δ H) is preferably the scope of 40～120J/g, the scope of 45～100 (J/g) more preferably, and be particularly preferably the scope of 45～85 (J/g).
1 expanded particle (P1) satisfies condition, as shown in Figure 1, on a DSC curve, there is more than 3 endotherm(ic)peaks, and the heat of each endotherm(ic)peak (Δ Ha, Δ Hb, Δ Hc......), can obtain by the part method of area analysis hereinafter described.
Based on Fig. 1 declaratives method of area analysis.On the DSC of gained curve, connect corresponding to the some α on the DSC curve of 80 ℃ with corresponding to the some β on the DSC curve of resin melting end temp Te, draw line segment (alpha-beta).Then, from the viewed peak a of the minimum low-temp. portion of temperature 1with with peak a 1adjacent peak a 2between the DSC curve of the lowest point part on some γ 1, draw the straight line parallel with the longitudinal axis of figure, using the intersection point of itself and aforementioned line segment (alpha-beta) as δ 1.In addition, owing to observing and peak a 2adjacent peak a 3, from peak a 2with with peak a 2adjacent peak a 3between the DSC curve of the lowest point part on some γ 2, draw the straight line parallel with the longitudinal axis of figure, using the intersection point of itself and aforementioned line segment (alpha-beta) as δ 2.After, observing peak a 4, peak a 5, peak a 6... time, repeat same operation.Line segment (δ n-γ n) (n is more than 1 integer) by aforesaid operations gained forms the boundary line at each peak when determining endotherm(ic)peak area.
Therefore, corresponding to the area at each peak of endotherm(ic)peak heat, in Fig. 1, for peak a 1, for representing peak a 1dSC curve, line segment (δ 1-γ 1) and line segment (α-δ 1) area that surrounds, for peak a 2, for representing peak a 2dSC curve, line segment (δ 1-γ 1), line segment (δ 2-γ 2) and line segment (δ 1-δ 2) area that surrounds, for peak a 3, for representing peak a 3dSC curve, line segment (δ 2-γ 2) and line segment (δ 2-β) area surrounding.After, observing peak a 4, peak a 5, peak a 6... time, also can determine peak area by identical main points.Therefore, the heat at each peak (Δ Ha, Δ Hb, Δ Hc......) J/g, the area based on above-mentioned each definite peak, is used DSC device to calculate and automatically calculates.In addition,, in Fig. 1, total endotherm(ic)peak heat (Δ H), is equivalent to the heat summation (Δ H=Δ Ha+ Δ Hb+ Δ Hc) of each endotherm(ic)peak.
In addition, in said determination method, in order to draw the line segment (alpha-beta) as baseline, the reason of point α using the point corresponding with 80 ℃ of temperature on DSC curve, because the point of take corresponding to 80 ℃ is starting point, using the baseline as terminal corresponding to the point of melting end temp, it is suitable for reproducibility well and stably obtains the heat of endotherm(ic)peak.
1 expanded particle (P1) satisfies condition, have in an aforementioned DSC curve, occur that summit temperature (PTmA) is shown as the crystal structure that 100～140 ℃ and endotherm(ic)peak heat are 70～95% main endotherm(ic)peak of total endotherm(ic)peak heat (Δ H).Therefore, in the DSC curve of the expanded particle of Fig. 1, endotherm(ic)peak a 1represent main endotherm(ic)peak.In addition, this expanded particle (P1), has in a DSC curve, occurs the crystal structure of more than 2 endotherm(ic)peak at this main endotherm(ic)peak high temperature side.Therefore, in the DSC curve of the expanded particle of Fig. 1, endotherm(ic)peak a 2, a 3expression is than main endotherm(ic)peak a 1more be positioned at 2 endotherm(ic)peaks of high temperature side.
In 1 the expanded particle (P1) of satisfying condition, it is 70～95% of total endotherm(ic)peak heat (Δ H) that summit temperature (PTmA) is shown as 100～140 ℃ and endotherm(ic)peak heat, refer in more than 3 endotherm(ic)peak occurring in an aforementioned DSC curve of expanded particle, for summit temperature (PTmA), be shown as any endotherm(ic)peak of 100～140 ℃, this endotherm(ic)peak heat with respect to the percentage of total endotherm(ic)peak heat (Δ H) (for example, in Fig. 1, (Δ Ha/ Δ H) * 100) be 70～95%.
In addition, from the thermotolerance viewpoint of gained expanded particle formed body and the viewpoint that further reduces mold temperature when in-molded consider, endotherm(ic)peak summit temperature (PTmA) of this main endotherm(ic)peak is preferably 105～135 ℃, and more preferably more than 110 ℃ and less than 125 ℃.
In addition, from improving the viewpoint consideration of the physical property such as physical strength, thermotolerance with the balance of expanded particle in-molded property at low temperatures of gained expanded particle formed body, in 1 the expanded particle (P1) of satisfying condition, the endotherm(ic)peak heat of this main endotherm(ic)peak is preferably 80～95% of total endotherm(ic)peak heat (Δ H), and more preferably 85～92%.
More than 2 endotherm(ic)peak occurring at the high temperature side of this main endotherm(ic)peak, can be by selecting the mixture of multiple acrylic resin, or selective polymerization catalyzer or polymerizing condition etc. and form, and, by except mixing multiple acrylic resin, also carry out isothermal crystalization operation described later (in making the operation of resin particle foaming, acrylic resin particle is kept to the specified time near the temperature its melting point resin, thereby make the operation of acrylic resin recrystallization), can reliably and easily form.
In addition, as previously mentioned, more than 2 endotherm(ic)peak occurring when the high temperature side in main endotherm(ic)peak be by the mixing of multiple acrylic resin and isothermal crystalization operation in expanded particle (P1) during formed crystal structure, these 2 above endotherm(ic)peaks can be divided into the endotherm(ic)peak of acrylic resin (P1a) composition of the main endotherm(ic)peak of the formation expanded particle (P1) coming from acrylic resin mixture, and by the formed endotherm(ic)peak of other propylene resin (P1b) composition.
In endotherm(ic)peak at this more than 2, the endotherm(ic)peak that comes from acrylic resin (P1a) composition that forms above-mentioned main endotherm(ic)peak, be in manufacturing the operation of expanded particle (P1), by forming the isothermal crystal of the acrylic resin (P1a) of main endotherm(ic)peak, operate formed endotherm(ic)peak.In addition, 2 above endotherm(ic)peaks that the high temperature side of main endotherm(ic)peak occurs, whether comprise that to come from the endotherm(ic)peak of lower melting propylene resin (P1a) composition that forms main endotherm(ic)peak in acrylic resin (following, be sometimes referred to as high temperature peak) and by the formed endotherm(ic)peak of other high-melting-point acrylic resin (P1b) composition, can confirm by the DSC of following expanded particle.
Use DSC device with 2 (℃/min) heat-up rate 1～3mg expanded particle is heated to 200 ℃ from normal temperature (general 25 ℃), obtain a DSC curve.Then, after arriving the temperature of 200 ℃, at once with 10 (℃/min) speed of cooling it is cooled to 25 ℃ from 200 ℃, after arriving the temperature of 25 ℃, again at once with 2 (℃/min) heat-up rate be heated to 200 ℃ from 25 ℃, obtain the 2nd DSC curve.
Satisfy condition in 1 expanded particle (P1), more than 2 endotherm(ic)peak occurring when the high temperature side in main endotherm(ic)peak, comprise lower melting propylene resin (P1a) composition that forms main endotherm(ic)peak in acrylic resin and operate formed endotherm(ic)peak by isothermal crystal, when by the formed endotherm(ic)peak of other high-melting-point acrylic resin (P1b) composition, by in a DSC curve of aforesaid method gained, at the high temperature side of main endotherm(ic)peak, there is more than 2 endotherm(ic)peaks.
On the other hand, in the 2nd DSC curve by aforesaid method gained, the quantity of the existing endotherm(ic)peak of high temperature side of main endotherm(ic)peak reduces (wherein, the endotherm(ic)peak of main endotherm(ic)peak high temperature side has more than 1).So, by an above-mentioned DSC curve and above-mentioned the 2nd DSC curve are compared, can confirm that the main endotherm(ic)peak occurring is more arranged in more than 2 endotherm(ic)peak of high temperature side in than a DSC curve, at least one endotherm(ic)peak disappears in the 2nd DSC curve.By this relatively, can think that the endotherm(ic)peak disappearing is that to come from the lower melting propylene that forms main endotherm(ic)peak be the endotherm(ic)peak of resin (P1a) composition, the endotherm(ic)peak that remains in main endotherm(ic)peak high temperature side is by the formed endotherm(ic)peak of other high-melting-point propylene resin (P1b) composition.For example,, in a DSC curve of the expanded particle of Fig. 1, at main endotherm(ic)peak a 1high temperature side there are 2 endotherm(ic)peak a 2, a 3.Then, in the 2nd DSC curve of this expanded particle of Fig. 2, at the high temperature side of main endotherm(ic)peak, only there is 1 endotherm(ic)peak a 3, and endotherm(ic)peak a 2disappeared.At this moment, can think the endotherm(ic)peak a disappearing 2that to come from the lower melting propylene that forms main endotherm(ic)peak be the endotherm(ic)peak of resin (P1a) composition, endotherm(ic)peak a 3by the formed endotherm(ic)peak of other high-melting-point propylene resin (P1b) composition.
In addition, while obtaining the 2nd DSC curve by DSC, from the speed of cooling of 200 ℃ to 25 ℃ be made as 10 (℃/min) reason, and when obtaining the 2nd DSC curve, from the heat-up rates of 25 ℃ to 200 ℃ be made as 2 (℃/min) reason, with when obtaining a DSC curve, heat-up rate is made as to 2 (℃/min) reason identical, for according to different types of crystal, improve the resolving power of endotherm(ic)peak and measure, and for a DSC curve and the 2nd DSC curve are contrasted, need to make condition determination consistent, and when speed of cooling is crossed when slow, not preferred.
In addition, in the aforementioned DSC curve of 1 expanded particle (P1) that satisfies condition, be present in 2 of main endotherm(ic)peak high temperature side above endotherm(ic)peaks, the endotherm(ic)peak heat at aforementioned high temperature peak is preferably the scope of 2～15 (J/g), and 3～12 (J/g) more preferably.By by this endotherm(ic)peak heat regulation in above-mentioned scope, can make the mechanical properties of expanded particle and the balance of second time of foaming become excellent especially, and from the viewpoint of obtaining the expanded particle formed body of dimensional stability, mechanical properties excellence, also can be used as more excellent expanded particle.In addition, from the viewpoint of operability and heat regulation stability, consider, preferably by the isothermal crystalization operation when manufacturing expanded particle described later, carry out the endotherm(ic)peak heat regulation at above-mentioned high temperature peak.
In addition, except using the method for isothermal crystalization operation, do not carrying out isothermal crystal operation, but method by the different multiple acrylic resin of mixed melting point etc., obtain when main endotherm(ic)peak high temperature side has the expanded particle of more than 2 crystal structure of endotherm(ic)peak, the reason of high temperature peak heat is identical with regulating, preferably by changing the ratio of mixture of the different multiple acrylic resin of fusing point, regulate, in 2 above endotherm(ic)peaks that the high temperature side of main endotherm(ic)peak is occurred, the endotherm(ic)peak heat of the endotherm(ic)peak of lowest temperature side is 2～15 (J/g), and be further the scope of 3～12 (J/g).
The summit temperature (PTmA) of the main endotherm(ic)peak 1 expanded particle (P1) the DSC curve at the DSC gained of the heat-up rate of a DSC curve of Fig. 1 (by using 2 (℃/min) that satisfies condition in addition) and this expanded particle are at the 2nd DSC curve of the DSC gained of the heat-up rate of the 2nd DSC curve of Fig. 2 (by using 2 (℃/min)) in the summit temperature (TmA) of endotherm(ic)peak approximate.
As fusion, preferentially carry out type expanded particle, as mentioned above, 1 the expanded particle of satisfying condition is illustrated, but the particle that type expanded particle is not limited to meet above-mentioned condition 1 is preferentially carried out in fusion, the expanded particle that meets aftermentioned condition 2,3 is also to fuse preferentially to carry out type expanded particle.In addition,, in 1 the expanded particle of satisfying condition, certainly also there is the expanded particle that simultaneously meets aftermentioned condition 2 and/or 3.
(1-2) satisfy condition 2 polypropylene-based resin expanded particle (P2)
The condition 2 of polypropylene-based resin expanded particle given to this invention is, it is substrate resin than the mixture of the high more than 20 ℃ high-melting-point acrylic resin (P2b) of this low melting point acrylic resin (P2a) that polypropylene-based resin expanded particle be take low melting point acrylic resin (P2a) and 20～2 weight part fusing points that 80～98 weight part fusing points are 100～140 ℃.Wherein, the gross weight of low melting point acrylic resin (P2a) and high-melting-point acrylic resin (P2b) is 100 weight parts, and their fusing point can adopt the measuring method identical with the melt temperature of aforementioned expanded particle to try to achieve.
In the expanded particle by hybrid resin gained (P2) in-molded, from reducing the viewpoint of expanded particle fusion temperature, consider, preferably mix 80～98 above-mentioned low melting point acrylic resins of weight part (P2a).In addition, this,, guaranteeing aspect the thermotolerance of gained expanded particle formed body, is also preferred.
From above-mentioned viewpoint, consider, the fusing point of low melting point acrylic resin (P2a), be preferably 105～135 ℃, more preferably 105～130 ℃, and be particularly preferably 110～125 ℃, the use level of low melting point acrylic resin (P2a), is preferably 90～98 weight parts, more preferably 92～95 weight parts.
On the other hand, when the expanded particle by hybrid resin gained (P2) in-molded, from reducing the viewpoint consideration that effect improves expanded particle rigidity in the situation that do not hinder the fusion temperature of the expanded particle of realizing by cooperation low melting point acrylic resin (P2a), preferably mix 20～2 above-mentioned high-melting-point acrylic resins of weight part (P2b).
From above-mentioned viewpoint, consider, the melting temperature of low melting point acrylic resin (P2a) and high-melting-point acrylic resin (P2b) is poor, be preferably more than 25 ℃, and more preferably more than 30 ℃, the use level of high-melting-point acrylic resin (P2b), be preferably 10～2 weight parts, more preferably 8～5 weight parts.
This expanded particle (P2), by comprising the substrate resin that has coordinated specified quantitative low melting point acrylic resin (P2a), can reduce the fusion temperature of expanded particle when in-molded.In addition, by comprising the substrate resin that has coordinated specified quantitative high-melting-point acrylic resin (P2b), played the effect that limits expanded particle second time of foaming when in-molded.Therefore, this expanded particle (P2) preferentially carries out type expanded particle for fusion, and the in-molded temperature range of expanded particle is expanded to low temperature side, and fusion character when in-molded between expanded particle has also improved.In addition, this expanded particle (P2), by form high temperature described later peak when manufacturing expanded particle, realize aspect the object of the invention more applicable.
Aforementioned low melting point acrylic resin (P2a), is the acrylic resin of 100～140 ℃ from the viewpoint of obtaining fusing point, is preferably propylene and ethene and/or carbonatoms and is the random copolymers of 4～20 alpha-olefin.
When aforementioned low melting point acrylic resin (P2a) comprises acrylic resin random copolymers, as the comonomer that carries out copolymerization with propylene, can enumerate ethene, 1-butylene, 1-amylene, 1-hexene, 1-octene, 4-methyl isophthalic acid-butylene etc.Therefore,, as low melting point acrylic resin (P2a), specifically, can enumerate propylene-ethylene random copolymers, propylene-1-butylene random copolymers, propylene-ethylene-1-butylene random copolymers etc.In addition, ethene in low melting point acrylic resin (P2a) becomes the alpha-olefin that subdivision and/or carbonatoms are 4～20 to become subdivision, from fusing point and the viewpoint that maintains physical strength, consider, be preferably 0.01～8 % by weight, and 0.05～5 % by weight more preferably.
As low melting point acrylic resin (P2a), more preferably using metallocene is polymerizing catalyst, makes propylene and comonomer carry out propylene-ethylene random copolymers, propylene-1-butylene random copolymers, propylene-ethylene-1-butylene random copolymers of copolymerization gained.
By choice for use metallocene, be that the material of polymerizing catalyst polymerization gained is as low melting point acrylic resin (P2a), mix with high-melting-point acrylic resin (P2b), the fusing point that makes low melting point acrylic resin composition in hybrid resin with mix in the fusing point of this low melting point acrylic resin of using compare to low temperature side displacement 5 ℃ of left and right for example, therefore by the expanded particle of this hybrid resin gained, can further reduce Heating temperature when in-molded.
In addition, using metallocene is that the low melting point acrylic resin (P2a) of polymerizing catalyst gained and the consistency of high-melting-point acrylic resin (P2b) are excellent.
As above-mentioned high-melting-point acrylic resin (P2b), for example, can enumerate segmented copolymer, propylene and the ethene that alfon, propylene and ethene and/or carbonatoms are 4～20 alpha-olefin and/or the few random copolymers of content alpha-olefin, this comonomer that carbonatoms is 4～20.
As fusion, preferentially carry out type expanded particle, as mentioned above, although 2 expanded particle is illustrated to satisfying condition, but the particle that type expanded particle is not limited to meet above-mentioned condition 2 is preferentially carried out in fusion, and the expanded particle that meets aforementioned condition 1, aftermentioned condition 3 is also to fuse preferentially to carry out type expanded particle.In addition,, in 2 the expanded particle of satisfying condition, certainly also there is the expanded particle that simultaneously meets aforementioned condition 1 and/or aftermentioned condition 3.
(1-3) satisfy condition 3 polypropylene-based resin expanded particle (P3)
In the present invention, the condition 3 of the polypropylene-based resin expanded particle of defined is, in DSC measures, with the heat-up rates of 10 ℃/min, polypropylene-based resin expanded particle is heated to 200 ℃ from normal temperature, with the cooling rates of 10 ℃/min, be cooled to 30 ℃, and then be heated in the 2nd DSC curve of 200 ℃ of gained with the heat-up rate of 10 ℃/min, from 80 ℃ to the melting heat (dH than the temperature of low 5 ℃ of the fusing point of this polypropylene-based resin expanded particle l) divided by total endotherm(ic)peak heat (dH t) heat of gained is than (dH l/ dH t) be 0.55～0.80.In addition, at this moment obtain for obtaining dH l, dH tthe step of DSC curve, identical with the measuring method of aforementioned expanded particle melt temperature.
Above-mentioned heat is than (dH l/ dH t), the thermal property that represents expanded particle substrate resin, and from can be in the angle of reduction expanded particle fusion temperature expanded particle (P3) in-molded, and can be in the situation that do not hinder the fusion temperature of expanded particle when in-molded and reduce the angle that effect improves expanded particle rigidity and consider, heat is than (dH l/ dH t) be preferably 0.55～0.80, in addition, by obtaining this heat than (dH l/ dH t), can also guarantee the thermotolerance of gained expanded particle formed body.
From above-mentioned viewpoint, consider, heat is than (dH l/ dH t) be preferably 0.57～0.80, more preferably 0.50～0.75.In addition dH, tbe preferably 40～90J/g, 45～75J/g more preferably, and be particularly preferably 45～70J/g.
This expanded particle (P3), by meeting specific heat than (dH l/ dH t), can reduce the fusion temperature of expanded particle when in-molded, meanwhile, played the effect that limits expanded particle second time of foaming when in-molded.Therefore, this expanded particle (P3) preferentially carries out type expanded particle for fusion, and the in-molded temperature range of expanded particle is expanded to low temperature side, and when in-molded, the mutual fusion character of expanded particle has also improved.In addition, this expanded particle (P3), by form high temperature described later peak when manufacturing expanded particle, becomes and is more suitable in realizing the object of the invention.
Form the substrate resin of this expanded particle (P3), can enumerate aforementioned homopolymer polypropylene, polypropylene copolymer or be selected from their mixture of more than two kinds.In these substrate resins, the fusion temperature that never hinders expanded particle when in-molded reduces the viewpoint that improves expanded particle rigidity in the situation of effect and considers, the polypropylene copolymer that preferably contains butylene composition, and polypropylene-ethylene-butylene copolymer particularly preferably.In addition, as the butene content of comonomer composition, be preferably 3～15 % by weight, more preferably 5～10 % by weight.
As fusion, preferentially carry out type expanded particle, as mentioned above, 3 the expanded particle of satisfying condition is illustrated, but the particle that type expanded particle is not limited to meet above-mentioned condition 3 is preferentially carried out in fusion, the expanded particle that meets aforementioned condition 1,2 is also to fuse preferentially to carry out type expanded particle.In addition,, in 3 the expanded particle of satisfying condition, certainly also there is the expanded particle that simultaneously meets aforementioned condition 1 and/or condition 2.
(1-4) other
(i) melt flow rate (MFR) of expanded particle substrate resin (MFR)
In manufacture method of the present invention, the melt flow rate (MFR) of the substrate resin of expanded particle used (MFR) is 5～60 (g/10 minute), more preferably 10～40 (g/10 minute).
In addition, when the substrate resin of expanded particle is while being consisted of the material that comprises above-mentioned low melting point acrylic resin and high-melting-point acrylic resin, the MFR of low melting point acrylic resin is preferably 1～100 (g/10 minute), 2～50 (g/10 minute) more preferably, the MFR of high-melting-point acrylic resin is preferably 0.1～50 (g/10 minute), more preferably 0.2～20 (g/10 minute).
In addition, this MFR is the value that the test conditions M (temperature is 230 ℃, loads as 2.16kg) based on JIS K7210 (1999) measures.
(ii) be added into other component of polymer, the additive of substrate resin
In forming manufacture method of the present invention in the acrylic resin of expanded particle substrate resin used, can, in granulating working procedure etc., in the scope of not damaging action effect of the present invention, coordinate other component of polymer or additive.
As aforesaid other component of polymer, for example, can enumerate high density polyethylene(HDPE), medium-density polyethylene, Low Density Polyethylene, straight chain shape Low Density Polyethylene, straight chain shape ultra-low density polyethylene, vinyl-vinyl acetate copolymer, ethylene-acrylic acid copolymer, the polyethylene-based resins such as ethylene-methacrylic acid copolymer, or polystyrene, the polystyrene resins such as styrene-maleic anhydride copolymer, ethylene-propylene is rubber, ethene-1-butylene rubber, propylene-1-butylene rubber, ethylene-propylene-diene series rubber, synthetic polyisoprene, chloroprene rubber, the rubber such as paracril, the thermoplastic elastomers such as the hydride of vinylbenzene-diene block copolymer or vinylbenzene-diene block copolymer etc.These resins, rubber or elastomerics can also combine two or more use.While coordinating above-mentioned other component of polymer in acrylic resin, total use level of these other component of polymer, with respect to the acrylic resin of 100 weight parts, is preferably adjusted to below 10 weight parts.
As aforementioned additive, can enumerate the various additives such as bubble conditioning agent, static inhibitor, electroconductibility imparting agent, lubricant, antioxidant, UV light absorber, fire retardant, metal passivator, pigment, dyestuff, crystallization nucleating agent or inorganic filling material, and can as required, they be engaged in the acrylic resin that forms expanded particle.The use level of these various additives, different and different according to adding purpose, but with respect to 100 weight part substrate resins, be preferably below 25 weight parts, more preferably below 15 weight parts, more preferably below 8 weight parts, and most preferably be below 5 weight parts.
In addition, form the substrate resin of expanded particle, from viewpoints such as reproducibility, expanded particle productivitys, consider, be preferably without cross-linked polypropylene resin.
(iii) granulation of resin particle
Be suitable for manufacturing the granulation of resin particle of the size of expanded particle, can adopt and use forcing machine that the substrate resin that comprises aforementioned acrylic resin is extruded as band shape, then be cut to the line cutting mode (ス ト ラ Application De カ ッ ト mode) of suitable length or the known prilling process in the past such as cutting mode under water.
During the substrate resin of expanded particle used comprises multiple acrylic resin in forming the present invention hybrid resin, use the mixing at least 2 kinds of resins of mixing roll, and mixing to both mixing fully and evenly.
Above-mentioned is fully mixing, for example, be preferably the high forcing machines of mixing property such as using biaxial extruder and carry out mixing method, or adopt the manufacturing process of the hungry forming method (Hunger Hungry recording in TOHKEMY 2006-69143 communique), use forcing machine to carry out mixing method.
Expanded particle used in the present invention, its each weight in average, is conventionally preferably 0.01～10.0mg, and is particularly preferably 0.1～5.0mg, the adjusting of its weight in average, can regulate by obtaining being used to form the above-mentioned granulating working procedure of the resin particle of expanded particle.
(1-5) manufacture of polypropylene-based resin expanded particle
Expanded particle used in manufacture method of the present invention, can use Japanese Patent Publication 49-2183 communique, Japanese Patent Publication 56-1344 communique, the known foaming method that Japanese Patent Publication 62-61227 communique etc. is recorded, , in encloses container, the acrylic resin particle and the whipping agent that by preceding method etc., carry out granulation gained are dispersed in the dispersion medium such as water, under agitation heating, when making resin particle softening, pneumatogen is infiltrated up in resin particle, then at the temperature more than the softening temperature of resin particle, resin particle is discharged in area of low pressure low in pressure ratio container (being generally atmospheric pressure region), make its foaming.In addition, in order to obtain expanded particle, and when the content in encloses container is discharged into area of low pressure from encloses container, from the homogenizing viewpoint of the apparent density of gained expanded particle, consider, preferably by inorganic gass such as pneumatogen used or nitrogen, air to applying back pressure in encloses container, make the pressure in this container can sharply not discharge content with declining.When manufacturing expanded particle, as dispersion resin dispersion of particles medium, be not limited to above-mentioned water, so long as do not dissolve the medium of resin particle, can use.As the dispersion medium beyond water, for example, can enumerate ethylene glycol, glycerol, methyl alcohol, ethanol etc., but conventionally make water.
In aforesaid method, for resin particle is dispersed in dispersion medium, preferably as required, the dispersion agents such as slightly water-soluble inorganic substance such as dispersed alumina, calcium phosphate, magnesium pyrophosphate, zinc oxide, kaolin in dispersion medium, the dispersing auxiliaries such as anionic surfactant such as Sodium dodecylbenzene sulfonate, alkyl sodium sulfonate.When manufacturing expanded particle, the amount of adding the dispersion agent in dispersion medium to, the ratio (weight of the weight/dispersion agent of resin particle) in weight and the dispersion agent weight of resin particle, is preferably 20～2000, and more preferably 30～1000.In addition, the ratio of the weight of dispersion agent and dispersing auxiliary weight (weight of the weight/dispersing auxiliary of dispersion agent) is preferably 1～500, and more preferably 5～100.
The mean air bubble diameter of expanded particle used in the present invention, is generally 30～500 μ m, and is preferably 50～350 μ m.The expanded particle with the mean air bubble diameter in above-mentioned scope, considers from the strength relationship of bubble chamber film, when expanded particle described later in-molded, does not form the risk of the broken bubble of Bubble formation of expanded particle, has demonstrated good in-molded property.
The mean air bubble diameter of aforementioned expanded particle, can divide the enlarged photograph of the bubble section of gained based on using microscope photographing that expanded particle is cut into general 2 grades, and obtain by following operation.In the enlarged photograph of above-mentioned bubble section, on 8 directions from central part to expanded particle surface, with the radial approximate centre of 4 surfaces from expanded particle by bubble section that draw until another surperficial straight line.Then, obtain and aforementioned 4 total number of bubbles that straight line is crossing: N (individual).Then, with aforementioned 4 straight lines, respectively since expanded particle surface, arrive the summation of another surperficial line segment length: L (μ m) divided by total number of bubbles: N (individual) (L/N), and the mean air bubble diameter using the value of obtaining as expanded particle.
In addition, due to aforementioned mean air bubble diameter, along with the minimizing of high MFRization, the raising of blowing temperature, the minimizing of whipping agent and the bubble conditioning agent of substrate resin etc., become large, therefore can pass through suitably to regulate the changing factor of these mean air bubble diameters, and obtain the expanded particle of object mean air bubble diameter.
In addition, control method as the mean air bubble diameter of aforementioned expanded particle, mainly by manufacturing when obtaining the resin particle of expanded particle, the ratio that to take with respect to 100 weight part substrate resins be 0.01～5 weight part, in substrate resin, coordinate talcum, aluminium hydroxide, silicon-dioxide, zeolite, the inorganicss such as borax carry out as bubble conditioning agent, but the blowing temperature while manufacturing because of above-mentioned expanded particle due to this mean air bubble diameter or the kind of whipping agent and usage quantity etc. change, therefore, in order to obtain having the expanded particle of object mean air bubble diameter, need to carry out preliminary experiment imposes a condition.
In the present invention, used 1～3 at least one the expanded particle that satisfies condition preferably has aforesaid high temperature peak.
The expanded particle with high temperature peak can suitably obtain by following method, , in aforementioned known foaming method, in encloses container, resin particle is dispersed in while heating in dispersion medium, the melting end temp that is not warming up to resin particle is (following, also referred to as Te) more than, but (following than the fusing point of resin particle, also referred to as Tm) temperature of low 15 ℃ is above and less than stopping heating under the arbitrary temp Ta in the scope of Te, and keep time enough under this temperature T a, preferably keep about 10～60 minutes, then, the arbitrary temp Tb of be adjusted to (Tm-5 ℃)～scope of (Te+5 ℃), and at this temperature, resin particle is discharged in area of low pressure from container, make the method for its foaming.In addition, in order to form high temperature peak, and more than remaining on above-mentioned (Tm-15 ℃) and less than the process in the scope of Te, can in this temperature range, set a plurality of stages, in addition also can be in this temperature range through time enough (slow and sequentially (continuously)) (the slowly and sequentially (continuously)) that slowly heat up.
The formation at the above-mentioned high temperature peak of expanded particle, and the size of the endotherm(ic)peak heat at high temperature peak, mainly exist with ... while manufacturing expanded particle for the said temperature Ta of resin particle and the hold-time under this temperature T a, said temperature Tb, and the heat-up rate in the scope of (Tm-15 ℃)～(Te+5 ℃).
The heat at the above-mentioned high temperature peak of expanded particle, when (1) temperature T a or Tb lower in above-mentioned each temperature range, (2) more than (Tm-15 ℃) and less than the hold-time in the scope of Te longer, and (3) are more than (Tm-15 ℃) and slower less than the heat-up rate in the scope of Te, larger.In addition, above-mentioned heat-up rate conventionally 0.5～5 (℃/min) scope in select.On the other hand, the heat at the above-mentioned high temperature peak of expanded particle, when temperature T a or Tb higher in above-mentioned each temperature range, more than (Tm-15 ℃) and less than the hold-time in the scope of Te shorter, and more than (Tm-15 ℃) and faster less than the heat-up rate in the scope of Te, in the scope of Te～(Te+5 ℃), heat-up rate is slower, less.Consider these aspects, if repeatedly carry out preliminary experiment, can know the creating conditions of expanded particle that demonstrates desirable high temperature peak heat.In addition, the temperature range at above-mentioned formation high temperature peak, is that using inorganic is the suitable temperature range of pneumatogen during as whipping agent.Therefore,, when whipping agent changes to organic system pneumatogen, according to its kind or usage quantity, its suitable temperature range is respectively to 0～30 ℃ of left and right of low temperature sidesway by said temperature scope.
As whipping agent used in aforesaid method, can use organic system pneumatogen or inorganic be pneumatogen, or their mixture etc.As organic system pneumatogen, can enumerate the aliphatic hydrocarbons such as propane, butane, hexane, pentane, heptane, the ester ring type such as tetramethylene, hexanaphthene hydrocarbon, the halohydrocarbon such as methyl chloride, monochloroethane, methylene dichloride, the dialkyl ethers such as dme, diethyl ether, methyl ethyl ether etc., and they can use a kind or two or more mix is used.In addition, as inorganic be pneumatogen, can enumerate nitrogen, carbonic acid gas, argon, air, water etc., and they can use a kind or two or more mix is used.By organic system pneumatogen and inorganic be physical foaming agent and mixing while using, can from above-mentioned organic system pneumatogen and inorganic be pneumatogen, to select arbitrarily and be used in combination.In addition, be combined with organic system pneumatogen and inorganic while being pneumatogen, preferably in whipping agent, containing more than at least 30 % by weight inorganic is pneumatogen.
The apparent density of polypropylene-based resin expanded particle used in the present invention, can easily regulate the infiltration amount of resin particle by above-mentioned whipping agent.
In above-mentioned whipping agent, particularly from the viewpoint of environment protection, consider, preferably inorganic is pneumatogen, wherein preferred nitrogen, air, carbonic acid gas, water.In addition, when obtaining expanded particle, while making water as dispersion medium together with resin particle in encloses container, by absorbent resin etc. and this resin particle being carried out mixing and using, can be using the water as dispersion medium effectively as whipping agent.
The usage quantity of whipping agent, considers the kind etc. of the apparent density of object expanded particle, the kind of substrate resin or whipping agent and determines.Conventionally, preferably in container, supply with pneumatogen, making the pressure of space segment in encloses container is 0.05～10MPa (G), and is further 1～8MPa (G).
Use preceding method, the resin particle of the soft state that contains whipping agent is discharged into from encloses container to the polypropylene-based resin expanded particle of gained in area of low pressure, after release, through common the carried out health operation under atmospheric pressure region (the raw engineering of Yang), form the polypropylene-based resin expanded particle of in-molded use.
(2) manufacture method of polypropylene-based resin expanded particle formed body
As manufacture method of the present invention, for example can adopt: (1) is filled in the expanded particle of aforementioned in-molded use can heating and cooling and can switch, airtight known expanded particle is in the past in-molded with in the die cavity of mould, (2) then, by supply with Saturated water vapor pressure in mould, be 0.05～0.30MPa (G), be preferably the water vapour of 0.08～0.25MPa (G), foamable particle, expanded particle is expanded, and fusion each other, (3) then, the expanded particle formed body of cooling gained, and by it from the in-molded method of intermittent type of taking out in die cavity (for example, Japanese Patent Publication 4-46217 communique, the forming method of recording in Japanese Patent Publication 6-49795 communique etc.).
In addition, can be as required, the expanded particle of aforementioned in-molded use is joined to the encloses container for the expanded particle of aforementioned in-molded use is pressurizeed in advance, by gas under pressures such as air, regulate, making the pressure in encloses container is 0.01～1MPa (G), improve the pressure treatment of the pressure in expanded particle, pressure in expanded particle is adjusted to after 0.01～0.2MPa (G), fill it into aforementioned in-molded using in the die cavity of mould, carry out in-molded.
In addition, method as the water vapour heating in above-mentioned in-molded method, can adopt side heating (side adds Hot), a contrary side (a contrary side adds a Hot) heating, the known method in the past of the appropriately combined use of heating means such as is heated in both sides simultaneously, and particularly preferably according to preparation heating, in a side heating, in the method for a contrary side heating, the heated in sequence expanded particle that heats in both sides simultaneously.The Saturated water vapor pressure of above-mentioned 0.05～0.30MPa (G) when in addition, expanded particle is in-molded be in above-mentioned in-molded operation by heat, heat in both sides etc. the maximum value that heats the Saturated water vapor pressure that is supplied to the water vapour in mould in a side heating, in a contrary side simultaneously.
In addition, expanded particle formed body can also be manufactured by the following method, , pressure in expanded particle is adjusted to after 0.01～0.2MPa (G) as required, by the travelling belt along thering is the continuous moving up and down in the path of heating region and cooled region, expanded particle is supplied to continuously in the mould of formation, and when it passes through heating region, to supplying with Saturated water vapor pressure in mould, be 0.05～0.30MPa (G), be preferably the water vapour of 0.08～0.25MPa (G), foamable particle, expanded particle is expanded, and fusion each other, then, make it by cooled region, be undertaken cooling, then, the expanded particle formed body of gained is taken out in die cavity, and the in-molded method of the continous way that is cut to successively suitable length (for example, Japanese kokai publication hei 9-104026 communique, the forming method of recording in Japanese kokai publication hei 9-104027 communique and Japanese kokai publication hei 10-180888 communique etc.).
In manufacture method of the present invention, use in expanded particle in-molded, by using water vapour to heat, first form the state that the surface of expanded particle can fuse each other, then expanded particle self is softening, formation can second time of foaming state, form thus all excellent good expanded particle formed bodys of the mutual fusion character of outward appearance and expanded particle.In addition, even if produced heating inequality more or less when this is in-molded, but due to mold temperature wide ranges, also can form good expanded particle formed body.
In addition, when manufacturing highdensity expanded particle formed body, when polypropylene-based resin expanded particle in the past in-molded, can manufacture apparent density is the above expanded particles of 70 (g/L), and rate of compression during if not filling-foam particle in mould cavity is more than 20% high state, and uses and surpass the in-molded method that the high water vapor pressure of 0.30MPa (G) carries out saturated steam heating, be difficult to obtain good expanded particle formed body.But, manufacturing method according to the invention, there is following characteristics, do not need to adopt saturated steam heating, the in-molded method under high compression rate of this use high water vapor pressure, or compared in the past, even if do not improve the internal pressure that is filled to the expanded particle in mould, also can obtain good low range expanded particle formed body.
Therefore, the manufacture method of expanded particle formed body of the present invention is characterised in that the rate of compression that this expanded particle is filled in mould when in-molded is 0～15%.
Rate of compression when above-mentioned expanded particle is filled to mould cavity, can and be filled to the stacking volume of the expanded particle of mould by mould cavity internal volume: MV (L): BV (L), obtains according to the formula of (BV-MV)/MV * 100.In addition, be filled to the stacking volume of the expanded particle of mould: BV obtains as follows: be that expanded particle is encased in empty graduated cylinder, and by the weight (g) that is encased in the expanded particle of this graduated cylinder divided by the shown volume of cylinder scale (L), obtain the tap density of expanded particle, again the known expanded particle of tap density is filled in mould, by the weight (g) that is filled into this expanded particle in mould, divided by the tap density of this expanded particle, calculates.
Expanded particle formed body by manufacture method gained of the present invention, as previously mentioned, can be 100～720 (g/L) by using density, and meet at least one expanded particle of aforementioned condition 1～3, and the rate of compression when filling this expanded particle in mould is adjusted to 0～15%, carries out in-molded and obtain.In addition, from the viewpoint of the mutual fusion character of the expanded particle of expanded particle formed body and outward appearance, consider, above-mentioned rate of compression is preferably 3～15%, and more preferably 5～13%.
(3) polypropylene-based resin expanded particle formed body
Polypropylene-based resin expanded particle formed body of the present invention, that polypropylene-based resin expanded particle is filled into and in mould, carries out the expanded particle formed body that hot briquetting forms, it is characterized in that, the density of this expanded particle formed body is 60～450g/L, according in the test of the non-notch test method of the charpy impact intensity of JIS K7111-1 (2006), make test film fracture, material damage in all expanded particles on gained surface of fracture the fusion rate of the polypropylene-based resin expanded particle obtained of the ratio of expanded particle be more than 50%, the density ratio Ds/Dc of the density D s of the skin section of this expanded particle formed body and the internal density Dc of this expanded particle formed body is 1～2,
The polypropylene-based resin expanded particle that forms this expanded particle formed body meets at least one of aforementioned condition 1～condition 3.
Expanded particle formed body of the present invention is the expanded particle formed body that can obtain by manufacture method of the present invention.
Expanded particle formed body of the present invention, its expanded particle is closely fusion each other, and in the test that the non-notch test method according to the charpy impact intensity of JIS K7111-1 (2006) describing in detail at embodiment is carried out, make test film fracture, in all expanded particles on gained surface of fracture material damage the fusion rate of the expanded particle obtained of the ratio of expanded particle be more than 50%, be preferably more than 70%, there is the good mechanical properties such as compressive strength.In addition, this expanded particle formed body is lip-deep concavo-convex few, level and smooth, and dimensional stability is also excellent.
In addition, from objects such as desirable physical strength, resiliency, light weights, consider, the density of this expanded particle formed body is 60～450 (g/L), and is preferably 90～300 (g/L).
In addition, the density of expanded particle formed body (g/L), can obtain divided by the volume of being obtained by the physical dimension of this expanded particle formed body (L) by the weight (g) of expanded particle formed body.
Further, expanded particle formed body is characterised in that, the skin section density (Ds) of this expanded particle formed body (g/L) and the internal density (Dc) of this expanded particle formed body density ratio (Ds/Dc) (g/L) be 1～2.This represent the density distribution of expanded particle formed body compared with the past be uniform.Low range expanded particle formed body in the past, owing to being subject to the restriction of the manufacture method of expanded particle formed body, the skin section density of expanded particle formed body, far above internal density, just looks like to be that low-density foaming layer is clipped in the multilayered structure in highdensity foaming layer.Therefore, expanded particle formed body in the past, the density of its skin section is far above the ensemble average density of this expanded particle formed body, and its internal density is far below the ensemble average density of this expanded particle formed body.
The compressive strength of this expanded particle formed body in the past, due to when compressing this expanded particle formed body, first the much lower inside foam of density is out of shape, and is therefore difficult to obtain the compression physical property that global density is quite high.On the contrary, expanded particle formed body by manufacture method gained of the present invention, as previously mentioned, the density distribution of expanded particle formed body is compared with the past is uniform, therefore can show the high compression physical property that is equivalent to this density, meanwhile, the stability of mechanical properties is also excellent, and the physical property offset issue can improve secondary processing etc. time.From above-mentioned viewpoint, consider, the above-mentioned of expanded particle formed body is preferably 1.1～1.7 than (Ds/Dc), and more preferably 1.1～1.5, and be particularly preferably 1.2～1.4.In addition, the ratio (Ds/Dc) of expanded particle formed body, for the skin section of surperficial skin section and the inside (wrapping up in face), all meets above-mentioned than the relation of (Ds/Dc).
In addition, the skin section density (Ds) of expanded particle formed body (g/L) and internal density (Dc) measuring method (g/L) as described below.
The skin section of expanded particle formed body, comprises the surface that is referred to as expanded particle formed body epidermis side, and is from the surface of expanded particle formed body, on thickness direction to the dark part of 5mm.Therefore, the skin section density (Ds) of this expanded particle formed body, can be by cutting out skin section (as concrete example from expanded particle formed body, cut out the surface that comprises expanded particle formed body, and be from the surface of expanded particle formed body, on thickness direction, to the dark part of 5mm, form the rectangular parallelepiped sample of long 50mm, wide 50mm, thick 5mm), and obtain divided by the volume (L) of this sample with the sample weight cutting out (g).
On the other hand, the inside of expanded particle formed body, is the centre portions of expanded particle formed body, and it does not comprise the surface of expanded particle formed body, and is from the central authorities of expanded particle formed body thickness direction, to surperficial and the inside, to be respectively the part of 5mm.Therefore, the internal density of this expanded particle formed body (Dc), can be by cutting out inside (as concrete example from expanded particle formed body, cut out the surface that does not comprise expanded particle formed body, and be from the central authorities of expanded particle formed body thickness direction, to surperficial and the inside, to be respectively the part of 5mm, form the rectangular parallelepiped sample of long 50mm, wide 50mm, thick 10mm), and obtain divided by the volume (L) of this sample with the sample weight cutting out (g).
In addition, expanded particle formed body, the continuous air bubbles rate that the order C based on ASTM-D2856-70 obtains is preferably below 40%, more preferably below 30%, and most preferably is below 25%.The expanded particle formed body that continuous air bubbles rate is less, physical strength is more excellent.
Form the expanded particle of expanded particle formed body of the present invention, be characterised in that it is that type expanded particle is preferentially carried out at least one the fusion that meets aforementioned condition 1～3.Form the expanded particle of expanded particle formed body by meeting this condition, when expanded particle in-molded, because heating water steam fully arrives each corner in mould, thereby can homogeneous heating expanded particle, in addition, the mold temperature scope of expanded particle is expanded to low temperature side, even therefore when in-molded, in mould, the Heating temperature of expanded particle has produced difference more or less, also can realize the mutual good fusion of expanded particle, for these reasons, the expanded particle formed body of low expansion ratio was compared in the past, formed especially fusion rate high, expanded particle formed body skin section and inner density difference are little, and compression physical property is the expanded particle formed body of excellence also.
In addition,, for the aforementioned condition 1～3 that forms the expanded particle of expanded particle formed body of the present invention, this expanded particle changes minimum in the physical property of carrying out in-molded front and back.
Expanded particle formed body by manufacture method gained of the present invention, there is the characteristics such as resiliency, dimensional stability, rigidity, light weight, impact absorbing material etc. for wrapping material, material of construction or automobile be can be widely used in, and wrapping material, the automobile thin wall component of accurate electrical and electronic parts are particularly suitable for.
Embodiment
Below, by embodiments of the invention, comparative example, the present invention is specifically described.
Resin and proterties thereof used in embodiment, comparative example shown in following table 1.
[embodiment 1～6, and comparative example 1,2]
(1) manufacture of polypropylene-based resin expanded particle
Use the single axle extruding machine that internal diameter is 65mm, with the proportioning shown in table 2 by melting mixing together with the zinc borate of the acrylic resin described in table 1 and 500 ppm by weight is in forcing machine (but in embodiment 1～4, use this forcing machine to carry out melting mixing with following hungry operating condition), mixing thing is extruded into pencil from be arranged on the nozzle aperture of forcing machine front end, cooling in tank, become weight to be approximately 1mg this tractotomy again, dry, obtain resin particle.In addition, above-mentioned hungry operating condition, by aforementioned hungry forming method, fusing point, resin that melt viscosity difference is large is mixing to the method for good distribution each other, and be that feed device by capacity formula carries out feed when regulating the supply of resin, make with respect to the raw material supplying portion that is full of forcing machine with material resin particle, the resin discharge-amount of forcing machine when being full of routine in forcing machine and being full of operating condition with resin, below when the resin discharge-amount under identical screw speed is being full of running, the method for extruding.In embodiment 1～4, the discharge-amount (kg/ hour) during hungry running is 70% when being full of running.
The resin particle of the above-mentioned gained of 1kg is joined in the 5L encloses container with stirrer with 3L (liter) together with the water of dispersion medium, in dispersion medium, add 0.3 weight part as the kaolin (English name: Kaolin) of dispersion agent again, 0.004 weight part is as the sodium alkyl benzene sulfonate (trade(brand)name: ネ オ ゲ Application (English name: Neogen) S-20 of tensio-active agent, the first industrial drugmaker manufactures) (wherein, described 0.004 weight part is the sodium alkyl benzene sulfonate amount in ネ オ ゲ Application S-20), and 0.01 weight part Tai-Ace S 150, and to being pressed into pressurized air as whipping agent in encloses container to the pressure shown in table 2, under agitation be warming up to the blowing temperature shown in table 2, and keep at the same temperature 15 minutes, regulate the endotherm(ic)peak heat at high temperature peak, then content is disposed under normal atmosphere, obtain having the expanded particle of apparent density shown in table 2.In addition, above-mentioned weight part, is the weight part with respect to 100 parts by weight resin particles.The proterties of gained expanded particle is shown in table 2 in the lump.
(2) manufacture of expanded particle formed body
The flat board that the expanded particle of above-mentioned gained is filled in to long 250mm, wide 200mm, thick 50mm, with in mould, heats by water vapour, carries out in-moldedly under the in-molded condition shown in table 3, obtains tabular expanded particle formed body.By the expanded particle molding obtaining health 12 hours in the baking oven of 80 ℃, obtain polypropylene-based resin expanded particle molding.The proterties of gained expanded particle formed body is shown in table 3 in the lump.
Figure GSB00001044882800281
Figure GSB00001044882800291
(3) evaluation method of expanded particle and expanded particle formed body
The evaluation method of the expanded particle in table 2,3 and expanded particle formed body is as follows.
(3-1) evaluation method of the expanded particle in table 2 and expanded particle formed body
(i) apparent density of expanded particle and apparent density are than (ρ r) mensuration
The apparent density of expanded particle and apparent density are than (ρ r) mensuration, adopt the method for recording in aforementioned " (1) polypropylene-based resin expanded particle ".
(ii) mensuration of total endotherm(ic)peak heat of expanded particle, main endotherm(ic)peak heat and high temperature side endotherm(ic)peak heat
The mensuration of total endotherm(ic)peak heat of expanded particle, main endotherm(ic)peak heat and high temperature side endotherm(ic)peak heat adopts aforementioned (1-1) satisfy condition polypropylene-based resin expanded particle of 1 " in the method recorded.
(iii) the total endotherm(ic)peak heat (dH in the 2nd DSC t) and melting heat (dH l) mensuration
Total endotherm(ic)peak heat (dH in the 2nd DSC t) and melting heat (dH l) mensuration, adopt the method for recording in aforementioned " (1-3) satisfy condition 3 polypropylene-based resin expanded particle ".
(3-2) evaluation method of the expanded particle in table 3 and expanded particle formed body
(i) mensuration of the fusion pressure (PF) of expanded particle
A DSC curve based on expanded particle, the lower limit of the temperature of prediction expanded particle melt surface, and carry out the in-molded of expanded particle by being equivalent to the steam of the Saturated water vapor pressure of this lower limit temperature, the expanded particle formed body of gained is carried out to the evaluation of the mutual fusion character of following expanded particle, confirm that the fusion rate of expanded particle formed body is less than 50%.Then, except the Saturated water vapor pressure of steam is set high 0.01MPa, similarly carry out the evaluation of above-mentioned fusion character.Carry out successively the Saturated water vapor pressure of steam to set to such an extent that high 0.01MPa evaluates the operation of fusion character, until the fusion rate of expanded particle formed body reaches more than 50%, and this fusion rate is reached to 50% Saturated water vapor pressure (this fusion rate reaches more than 50% minimum Saturated water vapor pressure) when above for the first time as fusion pressure.In addition, the mould of above-mentioned in-molded use is that molding space is the rectangular shape of long 250mm, wide 250mm, thick 20mm, and rate of compression when expanded particle is filled in this mould is set as 10%.Be noted that using at temperature is to place the expanded particle that has carried out status adjustment for 48 hours under the condition under 23 ℃, the relative humidity normal atmosphere that is 50%, as expanded particle used in said determination.In addition, the fusion rate of above-mentioned expanded particle formed body is the value of obtaining by aftermentioned method.
(ii) mensuration of the second time of foaming pressure (PA) of expanded particle
A DSC curve based on expanded particle, the lower limit of the temperature of prediction expanded particle second time of foaming, and by being equivalent to the steam of the Saturated water vapor pressure of this lower limit temperature, at volume, be 5L (liter) and have in the encloses container of pressure regulator valve, to being about 100cm in stacking volume added 3expanded particle heated for 10 seconds, and measure the apparent density of the expanded particle after the heating of gained.Obtain the density ratio of apparent density (g/L) and the apparent density (g/L) before the heating of this expanded particle of the expanded particle after the heating as above measured, confirm that the value of [apparent density before heating (g/L)]/[apparent density after heating (g/L)] is less than 1.5.Then, except the Saturated water vapor pressure of steam is set high 0.01MPa, similarly carry out the evaluation of above-mentioned second time of foaming.Carry out successively the Saturated water vapor pressure of steam to set to such an extent that high 0.01MPa evaluates the operation of second time of foaming, until the value of the density ratio of expanded particle { [apparent density before heating (g/L)]/[apparent density after heating (g/L)] } reaches more than 1.5, and the value of this density ratio is reached to 1.5 Saturated water vapor pressures (value of this density ratio reaches more than 1.5 minimum Saturated water vapor pressures) when above for the first time as second time of foaming pressure.Be noted that using at temperature is to place the expanded particle that has carried out status adjustment for 48 hours, expanded particle used in measuring as above-mentioned apparent density under the condition under 23 ℃, the relative humidity normal atmosphere that is 50%.
(iii) mensuration of 50% stress under compression
(iii-1) with 50% stress under compression (A) of the test film of epidermis
50% stress under compression (A) with the test film of epidermis, from expanded particle formed body, to cut out the test film with epidermis of long 50mm, wide 50mm, thick (total thickness of formed body) 50mm, and according to JIS K6767 (1999), with the compression speed of 10mm/ minute compression testing sheet on thickness direction, carry out compression testing, obtain 50% stress under compression (A) of expanded particle formed body.
(iii-2) without 50% stress under compression (B) of the test film of epidermis
50% stress under compression (B) without the test film of epidermis, from expanded particle formed body, to cut out long 50mm, wide 50mm, the cubes of thick (total thickness of formed body) 50mm, further, in order to cut existing epidermis on the top and bottom of expanded particle formed body thickness direction, thickness with the 12.5mm that respectively does for oneself from the top and bottom of thickness direction cuts epidermis, form long 50mm, wide 50mm, the test film without epidermis of thick 25mm, and according to JIS K6767 (1999), with the compression speed of 10mm/ minute compression testing sheet on thickness direction, carry out compression testing, obtain 50% stress under compression (B) of expanded particle formed body.
(iv) density measurement of expanded particle formed body
The density of expanded particle formed body, obtains divided by volume (L) by the weight with this expanded particle formed body (g).
(v) density D of the skin section of expanded particle formed body swith internal density D cdensity ratio (D s/ D c) mensuration
Density ratio (D s/ D c) mensuration, adopt the method for recording in aforementioned " (3) polypropylene-based resin expanded particle formed body ".
(vi) mensuration of test film density
(vi-1) with the test film density of epidermis
Test film density with epidermis, be from expanded particle formed body, to cut out the test film with epidermis of long 50mm, wide 50mm, thick (total thickness of formed body) 50mm, and obtain divided by the volume (L) of this test film by test film weight (g).
(vi-2) without the test film density of epidermis
Test film density without epidermis, from expanded particle formed body, to cut out the cubes of long 50mm, wide 50mm, thick (total thickness of formed body) 50mm, further, in order to cut existing epidermis on the top and bottom of expanded particle formed body thickness direction, thickness with the 12.5mm that respectively does for oneself from the top and bottom of thickness direction cuts epidermis, form the test film without epidermis of long 50mm, wide 50mm, thick 25mm, and obtain divided by the volume (L) of this test film by test film weight (g).
(vii) fusion character
The expanded particle fusion rate of expanded particle formed body, except test film size being changed to longitudinal 10mm, laterally 10mm, length are 80mm, non-notch test method according to the charpy impact intensity of JIS K7111-1 (2006) is tested, make test film fracture, and by material damage on surface of fracture the ratio of expanded particle obtain.In addition, when test film does not rupture, fusion rate is 100%.
Fusion rate=material damage expanded particle number (individual)/section (longitudinally 10mm, laterally 10mm) on total expanded particle number (individual) * 100
According to the fusion rate as above obtained, according to following benchmark, evaluate.
◎: fusion rate is more than 70%
Zero: fusion rate is more than 50% and less than 70%
△: fusion rate is more than 30% and less than 50%
*: fusion rate is less than 30%
(viii) outward appearance
By the surface of visual inspection expanded particle formed body, and according to following benchmark evaluation outward appearance.
Zero: on the surface of expanded particle formed body, almost there is no particle gap or concavo-convex, demonstrate good condition of surface.
△: can know on the surface of expanded particle formed body and confirm particle gap and/or concavo-convex.
*: particle gap and/or concavo-convex remarkable on the surface of expanded particle formed body.
(4) evaluation of expanded particle and expanded particle formed body
As shown in table 3, although the polypropylene-based resin expanded particle formed body in the embodiment of the present invention is the expanded particle formed body of low expansion ratio, the fusion character excellence that expanded particle is mutual, the outward appearance of this expanded particle formed body is also good.In addition, the skin section of expanded particle formed body and inner density ratio are below 2, compare with the expanded particle formed body in the past shown in comparative example, and this density ratio is close to 1, and the density uniformity of expanded particle formed body improves.
The polypropylene-based resin expanded particle formed body of the comparative example based on prior art in table 3, the fusion character that its expanded particle is mutual and outward appearance are not enough, or even if fusion character and outward appearance are in allowed limits, the skin section of expanded particle formed body and inner density uniformity are also not enough.
In addition, compressive strength about expanded particle formed body, between the equal densities formed body of the comparative example 1 by the embodiment of the present invention 3,4 and prior art in the comparison aspect 50% stress under compression of table 3, although known substrate resin is variant, but expanded particle formed body of the present invention, its compressive strength is more excellent than formed body in the past.In addition, for the value of the compression physical property ratio of table 3, by embodiment 1～6, compare known expanded particle formed body of the present invention with comparative example 1,2, the skin section of its expanded particle formed body and inner compressive strength are poor less than in the past, and the excellent in uniformity of compressive strength.
As shown in Table 3, although the polypropylene-based resin expanded particle shown in the embodiment of the present invention of table 2, vapor pressure when it is in-molded is low, and (particularly embodiment 1, although its vapor pressure is extremely low), also can obtain mutual fusion character and the good expanded particle formed body of outward appearance of expanded particle of expanded particle formed body.

Claims (2)

1. a polypropylene-based resin expanded particle formed body, it is that polypropylene-based resin expanded particle is filled in mould and carries out the expanded particle formed body that hot briquetting forms, it is characterized in that,
The density of this expanded particle formed body is 90g/L～300g/L, and the fusion rate of polypropylene-based resin expanded particle is more than 50%, and the skin section density of this expanded particle formed body is 1～2 divided by the density ratio of the internal density gained of this formed body,
The polypropylene-based resin expanded particle that forms this expanded particle formed body meets at least one in following condition 1 and condition 2,
Condition 1: there is following crystal structure,, in heat flux means of differential scanning calorimetry is measured, with the heat-up rates of 2 ℃/min, polypropylene-based resin expanded particle is heated to a DSC curve of 200 ℃ of gained from normal temperature, appearance is the main endotherm(ic)peak of 100 ℃～140 ℃ with respect to the endotherm(ic)peak heat of total endotherm(ic)peak heat demonstration 70%～95% and the summit temperature of endotherm(ic)peak, and the crystal structure that is positioned at 2 above endotherm(ic)peaks of this main endotherm(ic)peak high temperature side; Simultaneously, polypropylene-based resin expanded particle using low melting point acrylic resin that 80～98 weight part fusing points are 100 ℃～140 ℃ and 20～2 weight part fusing points than the mixture of the high more than 20 ℃ high-melting-point acrylic resin of this low melting point acrylic resin as substrate resin, described high-melting-point acrylic resin is selected from the segmented copolymer of the alpha-olefin that alfon, propylene and ethene and/or carbonatoms are 4～20;
Condition 2: in heat flux means of differential scanning calorimetry is measured, with the heat-up rates of 10 ℃/min, polypropylene-based resin expanded particle is heated to 200 ℃ from normal temperature, with the cooling rates of 10 ℃/min, be cooled to 30 ℃, and then be heated in the 2nd DSC curve of 200 ℃ of gained with the heat-up rate of 10 ℃/min, from 80 ℃ to being 0.55～0.80 than the melting heat of the temperature of low 5 ℃ of the fusing point of this polypropylene-based resin expanded particle divided by the heat ratio of total endotherm(ic)peak heat gained.
2. a manufacture method for polypropylene-based resin expanded particle formed body, it is polypropylene-based resin expanded particle to be filled in to the manufacture method of the expanded particle formed body that carries out hot briquetting in mould, it is characterized in that,
The apparent density of this polypropylene-based resin expanded particle is 150g/L～500g/L, and meanwhile, it meets following condition 1 and condition 2 at least one, and the rate of compression of this polypropylene-based resin expanded particle while being filled in mould be 0～15%,
Condition 1: there is following crystal structure,, in heat flux means of differential scanning calorimetry is measured, with the heat-up rates of 2 ℃/min, polypropylene-based resin expanded particle is heated to a DSC curve of 200 ℃ of gained from normal temperature, occurred that with respect to the endotherm(ic)peak heat of total endotherm(ic)peak heat demonstration 70%～95% and the summit temperature of endotherm(ic)peak be the main endotherm(ic)peak of 100 ℃～140 ℃, and the crystal structure that is positioned at 2 above endotherm(ic)peaks of this main endotherm(ic)peak high temperature side; Simultaneously, polypropylene-based resin expanded particle using low melting point acrylic resin that 80～98 weight part fusing points are 100 ℃～140 ℃ and 20～2 weight part fusing points than the mixture of the high more than 20 ℃ high-melting-point acrylic resin of this low melting point acrylic resin as substrate resin, described high-melting-point acrylic resin is selected from the segmented copolymer of the alpha-olefin that alfon, propylene and ethene and/or carbonatoms are 4～20;
Condition 2: in heat flux means of differential scanning calorimetry is measured, with the heat-up rates of 10 ℃/min, polypropylene-based resin expanded particle is heated to 200 ℃ from normal temperature, with the cooling rates of 10 ℃/min, be cooled to 30 ℃, and then be heated in the 2nd DSC curve of 200 ℃ of gained with the heat-up rate of 10 ℃/min, from 80 ℃ to being 0.55～0.80 than the melting heat of the temperature of low 5 ℃ of the fusing point of this polypropylene-based resin expanded particle divided by the heat ratio of total endotherm(ic)peak heat gained.
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