CN1413885A - High-separate layer hollow container and its preparation technology - Google Patents

Abstract

A high-isolating lamella hollow container used as fuel oil tank or packing bottle of agricultural chemical is prepared through preparing the isolating mother material from EVOH and compatibilizer (acrylic acid grafted polyethylene) and mixing with polyethylene. It has high isolation performance to hydrocarbon compounds and better mechanical performance.

Description

High-obstruction laminated hollow container and preparation technology thereof

Technical field

The present invention relates to a kind of barriers function hollow container goods that have, this container is prepared by high molecular material compositions, said composition is to be prepared into the obstruct masterbatch with ethylene/vinyl alcohol copolymer (EVOH), compatilizer, do to mix preparation with polyethylene again, the stratiform hollow product that adopts the said composition preparation is for hydro-carbon, and especially gasoline, dimethylbenzene equal solvent have excellent barriering effect and favorable mechanical performance.

Background technology

Along with the development of plastics industry, polyethylene is with its good physical and mechanical properties, moulding processability and advantage such as with low cost, and is widely used in producing various hollow package containers.But,, thereby limited polyethylene in application such as fields such as fuel tank of vehicle, pesticides packaging bottles because polyethylene when storing hydrocarbon compound (as dimethylbenzene, gasoline etc.) seepage and swelling can take place.Improve the infiltrative method of polyethylene packaging container chemically-resistant solvent at present and have following three kinds: 1) surface treatment method; 2) multi-layer co-extruded complex method; 3) the compound blocking method of blend.Surface treatment method is in container blowing process inner surface of container to be fluoridized or the sulfonation processing, by the change inner surface characteristic, and improve barrier, but this method environmental pollution is more serious, and equipment investment is higher.It is barrier material that multi-layer co-extruded method adopts polyamide or EVOH, rely on adhesives that barrier material and polyethylene are bonded together, make five layers or six layers of barrier container, this method equipment investment is huge, and the leftover pieces in the production process can not be recycled, the productive costs height.The compound obstruct rule of blend be with have the High molecular material of barriering effect such as polyamide, EVOH and polyethylene and compatilizer do mix after, extruder with mixing appropriateness melt extrudes parison, then blow molding, make polyamide in the polyethylene matrix, form many discrete, large-area laminar textures, thereby hindered the infiltration of solvent molecule, improved the barrier of container to organic liquid and gaseous material infiltration thereof, and its operational path is simple, with low cost, have application and development prospect preferably.

A kind of layered article by polyolefin and the preparation of ethylene/vinyl alcohol copolymer compound is disclosed among the Chinese patent CN 1047319.It is by polyolefin, EVOH and compatilizer preparation.Polyolefin content is 0～97.9wt%, ethylene-vinyl alcohol copolymer content is 2～20wt%, be preferably 4～15wt%, compatilizer is the polyolefin backbone of cyclic anhydride part in the grafting, and carbonyl content is 0.0014: 1.0～0.0016: 1.0 with the ratio of ethylene-vinyl alcohol copolymer in the compatilizer.Acetate unit content is at 20～60wt% among the EVOH in this patent, and its fusing point is higher than 5 ℃ of polyolefin, and this requirement mainly is that acetate unit content is no more than 60wt% in the restriction ethylene-vinyl alcohol copolymer, is that saponification degree is greater than 95% to another requirement of EVOH; Provide the EVOH melt viscosity in its specification sheets and be 1.1～3.5 times of polyolefin melt viscosity; Its used compatilizer is the cyclic anhydride of polyolefin grafted maleic anhydride, maleic acid monoesters, maleic acid and formic acid and carbon-to-carbon unsaturates, and carbonyl content is 0.3～4.0wt%.The technology that this patent is used is polyolefin and EVOH and compatilizer to be done directly extrude stretching after mixing, make final ethylene-vinyl alcohol copolymer with layered arrangement in polyolefin, i.e. one-step technology.

Summary of the invention

Though the prepared barrier container paraxylene of mentioning in disclosed prior art etc. has barrier property preferably, its barrier property and mechanical property await further to improve.Therefore, the objective of the invention is to start with, by the accuracy control of EVOH and polyethylene melt viscosity being prepared stratiform barrier container with more excellent barrier property and mechanical property from the composition of selection composite and the preparation technology of layered article; And the acrylic acid-grafted polyolefin by preferential employing nonhazardous is done compatilizer, has reduced the pollution in the preparation process, reaches the purpose of environmental protection.

Adopt the barrier property and the barrier material (EVOH of the hollow product of stratiform blend complex technique preparation, polyamide etc.) dispersing morphology in the semifinished piece is closely related, need to form good laminar texture in the EVOH semifinished piece, simultaneously for guaranteeing material good mechanical performance, it is bonding to have a good phase interface.For the co-mixing system of polyethylene/EVOH non-conforming, because polyethylene is a non-polar polymer and EVOH is a polar polymer, solubility parameter between the two differs bigger, causes the co-mixing system mechanical property very poor, therefore must add compatilizer to improve the mechanical property of blend.Simple polyethylene/EVOH blend can not be used as barrier material, has only when being scattered in the evoh layer shape in the polyethylene matrix, just can obtain good barriering effect.

Consisting of of the present composition: (A) polyolefin, preferably polyethylene (PE), melt flow rate (the 2.16Kg counterweight, 190 ℃, down together) be 0.01～0.3g/10min; (B) EVOH, melt flow rate is 3～8g/10min, contains the ethylene unit of 20～50Wt% among the EVOH; (C) the compatilizer polyethylene of monomer that has been grafting, used grafted monomers can be acrylic acid, maleic anhydride etc., and percent grafting is 1.0～3.0Wt%, and the melt flow rate of the compatilizer that is prepared into is 0.5～4.0g/10min.The parts by weight of each component are: component (A) 70～90, and component (B) 2～20, component (B) with the part by weight of component (C) is: 2: 1～5: 1.

The density of component of the present invention (A) is preferably in 0.95～0.97g/cm ³In, melt flow rate is preferably 0.1～0.3g/10min; The melt flow rate of component (B) is preferably 5～6g/10min, preferably contains the ethylene unit of 30～40Wt% among the EVOH; Because maleic anhydride can send the smell that stimulates eyes, respiratory system in the polypropylene fusion graft process, consider that for environmental protection the compatilizer of component (C) preferably uses acrylic acid fusion-grafting polyethylene.With the grafted monomers fusion-grafting to polyethylene (PE), be preferably on the low density polyethylene (LDPE) (LDPE), because in the melting graft reaction process, acrylic acid-grafted on the sub polyethylene subchain time, the part cross-linking reaction also can take place in polyethylene, so guarantee that compatilizer has suitable percent grafting and melt flow rate is extremely important, suitable percent grafting can be so that there be enough acrylic acid to participate in reaction, guarantee the effect of compatilizer, suitable melt flow rate can guarantee that it has good processing properties.

By component (B) with (C) extrude blend through extruder and make the obstruct masterbatch, definition melt viscosity ratio is with 220 ℃, and rate of shear is 100s ^-1The time intercept the melt viscosity of masterbatch divided by the polyolefinic melt viscosity of component (A) under this condition.Make goods have good BLEND ALLOYS WITH LAMINAR DISPERSED, select under the moulding processing conditions melt viscosity suitable between the EVOH and polyethylene than extremely important.The present invention controls the melt viscosity ratio by selecting different component (B) and ratios (C), reaches good barriering effect.

For reaching good barriering effect, we adopt following step on preparation technology:

(a) polyethylene and grafted monomers are melt extruded in extruder, extruder control range of temperatures is at 160～210 ℃, screw speed is 150～200RPM, and preparing percent grafting is 1.0～3.0Wt%, and melt flow rate is component (C) compatilizer of 0.5～4.0g/10min;

(b) with component (C) with (B) join melt blending granulation in the double screw extrusion machine in proportion, make the obstruct masterbatch, extruder temperature is controlled at 180～220 ℃, screw speed is 150～200RPM;

(c) will intercept masterbatch then and in high-speed mixer, mix 2～5 minutes, send into again in the blow molding machine, go out to intercept hollow container 200～220 ℃ of blow moldings with component (A).

In order to guarantee the formation of goods laminate form, avoid using the single screw extrusion machine of high shear type, preferably select low shearing, conveying type list screw rod for use.Under shear action when single screw rod of heterogeneous melt composition in blow molding machine extruded, form the container parison by the extruding dies lip, by inflation, stretching, and cooling and shaping finally obtains required high-obstruction laminated hollow product in the parison semifinished piece mould.Inflation, stretching can upwards be carried out at folk prescription, also can on orthogonal both direction, carry out, no matter unidirectional or biaxial tension, relative deformation rate at least one direction mo(u)ld top half embryo must be greater than 100%, be preferably 100～300% relative deformation rate, otherwise it is insufficient that heterogeneous melt blended material stretches, and evoh layer shape form is not obvious, can't reach the high barrier that goods of the present invention have.The cooling and shaping process is to make mold cools down by feeding cooling water expansion tank, thereby goods are cooled off.

Technology of the present invention compared with prior art, its difference is: (1) is adopted and to be melt extruded method and prepared acrylic acid-grafted low density polyethylene (LDPE) compatilizer; (2) adopted at first preparation intercept masterbatch (step b), will intercept again masterbatch and component (A) do mixed after, prepare the stratiform barrier container; (3) by regulating the blend proportioning between component (B) and the component (C), controlled the melt viscosity ratio between component (B) and the component (A) effectively.Because These characteristics of the present invention makes the present invention have the following advantages: (1) adopts acrylic acid-grafted low density polyethylene (LDPE) as compatilizer, helps environmental protection; (2) the present invention is owing to the melt viscosity ratio of having controlled effectively between component (B) and the component (A), and the technology of Cai Yonging helps component (B) forms the best in component (A) stratiform dispersed texture in addition, thereby makes hollow container have good barriering effect; (3) by the melt blending of step (b), compatilizer and EVOH are fully reacted, guaranteed that both best phase interfacies are bonding, improved the mechanical property of goods; (4) the little cross-linked structure that forms in compatilizer and the EVOH blend process is given EVOH good melt elasticity, and elastic deformation takes place under shear action easily, also helps forming laminar texture.

The hollow product that adopts composite of the present invention and preparation technology to make, barrier material EVOH are multilayer, laminar being dispersed in the polyolefin substrate, and the two-phase interface of polyolefin and EVOH is bonding firmly.The goods that its barriering effect is better than mentioning in the prior art.

Below with the specific embodiment effect of the present invention is described.

The specific embodiment

By component (B) and (C) extrude and make the obstruct masterbatch, make to have good BLEND ALLOYS WITH LAMINAR DISPERSED in the EVOH semifinished piece, select under the moulding processing conditions melt viscosity suitable between the EVOH and polyethylene than extremely important through the extruder blend.The present invention controls the melt viscosity ratio by selecting different component (B) and ratios (C).

With fusing point is 164 ℃, melt flow rate is 5.5g/10min, ethylene contents is that the ethylene/vinyl alcohol copolymer (EVOH) of 30Wt% is that (melt flow rate is 1.5g/10min to component (A) with acrylic acid-grafted low density polyethylene (LDPE) compatilizer, percent grafting is 2.0%) be that component (B) melt extrudes preparation obstruct masterbatch by the proportioning in the table 1, the screw diameter of used double screw extrusion machine is 30mm, processing temperature is 180～220 ℃, and screw speed is 150RPM.Under 220 ℃ of conditions, (melt flow rate is 0.25g/10min, and density is 0.951g/cm for test obstruct masterbatch and component (A) polyethylene ³) melt viscosity with the variation of rate of shear, and with 220 ℃, rate of shear is 100s ^-1The time intercept the melt viscosity of the melt viscosity of masterbatch divided by HDPE, obtain the melt viscosity ratio, as shown in table 1, as can be seen, it is big more to intercept the amount that compatilizer adds in the masterbatch, and melt viscosity is bigger more than also, so the addition of compatilizer has changed EVOH and poly melt viscosity ratio significantly, and we discover, the barrier property of melt viscosity comparison hollow product has material impact.According to table 1, the melt viscosity ratio should be chosen in 0.4～0.8 scope, preferably in 0.5～0.7 scope, is lower than this scope, and phase interface bonding relatively poor causes mechanical property and barrier property relatively poor; And be higher than this scope, and cause EVOH to be dispersed in meticulously in the polyethylene matrix in the time of the bonding grow of phase interface, be difficult to form the barrier layer of sheet, barriering effect is also relatively poor.

Table 1, intercept masterbatch and poly melt viscosity than (220 ℃, rate of shear 100s ^-1) Annotate: 1) this melt viscosity is than referring to not add the EVOH of compatilizer and the ratio of poly melt viscosity.

Adopting the four kinds of obstruct masterbatch (EVOH/ compatilizer) in the table 1 respectively is 0.951g/cm with density ³Melt flow rate is that the high density polyethylene (HDPE) of 0.25g/10min is sent in the high-speed mixer according to the proportioning in the table 2 and mixed 3 minutes, the content of EVOH is 10% (weight) in the blend composition of gained, again the composite of gained is sent in the German BEKUM product BM-08 of the company blow molding machine, under 200～220 ℃ condition, be processed into the bottle of 100ml, the heavily about 18g of bottle, the about 1mm of wall thickness.The bottle of preparation is got three, fill dimethylbenzene, after the sealing, according to ASTM 2684-89, measure 60 ℃ of weightlessness in following 16 days, based on the weight and the physical dimension of bottle, calculate the face area and the average wall thickness of bottle, calculate the osmotic value p of each bottle again, average.

Other gets three bottles and fills water, at room temperature (25 ℃) were placed 6 days, and the height of bottle from per 0.305 meter increase height dropped on the smooth concrete floor, and are destroyed up to bottle, room temperature is 15 ℃ in the experiment, calculates three maximum height aviation values that bottle can pass through.Table 3 is the performance comparison of embodiment and Comparative Examples (Chinese patent CN1047319A).

Table 2 composite is formed

Numbering	Composite is formed (parts by weight)
					Component (B) EVOH	Component (C) compatilizer	Intercept masterbatch component (B)+(C)	Component (A) polyethylene
	1# (EVOH/ compatilizer=5: 1)	????10	????2	????12					????88
2# (EVOH/ compatilizer=4: 1)					????10	????2.5	????12.5	????87.5
	3# (EVOH/ compatilizer=3: 1)	????10	????3.3	????13.3					????86.7
4# (EVOH/ compatilizer=2: 1)					????10	????5	????15	????85

Table 3 embodiment and Comparative Examples performance comparison

Numbering	The maximum height of fall (m)	Durchgriff (g.mm/ days .m2)
			????1#	????3.6	????3.6
????2#	????3.7	????3.2
			????3#	????4	????2.7
????4#	????4.2	????3.5
			Comparative Examples	????3.4	????3.8

As seen from Table 3, the durchgriff of embodiment all is lower than the durchgriff of Comparative Examples, is good with 2#, 3# especially, and therefore under this embodiment, control melt viscosity ratio is best in 0.5～0.7 scope.Change the content of EVOH in the composite or the kind or the consumption of change compatilizer, all can cause of the change of best melt viscosity, but use the scope that thinking of the present invention can be obtained best melt viscosity ratio, the hollow container that obtains having excellent barrier properties than scope.

Claims (7)

1. hollow container with barrier property, form by the composite that comprises following component:

(A) polyolefin, melt flow rate are 0.01～0.3g/10min;

(B) EVOH, melt flow rate is 3～8g/10min, contains the ethylene unit of 20～50Wt% among the EVOH;

(C) the compatilizer polyethylene of monomer that has been grafting, used grafted monomers is selected from acrylic acid, maleic anhydride, and percent grafting is 1.0～3.0Wt%, and the melt flow rate of the compatilizer that is prepared into is 0.5～4.0g/10min;

The parts by weight of each component are: component (A) 70～90, and component (B) 2～20, component (B) with the part by weight of component (C) is: 2: 1～5: 1;

Component in the hollow container (B) is to be scattered in the component (A) with the multilayer lamellar morphologies.

2. hollow container as claimed in claim 1 is characterized in that being in the component in its composite (A) polyethylene, density 0.95～0.97g/cm ³, melt flow rate is 0.1～0.3g/10min.

3. hollow container as claimed in claim 1, the melt flow rate that it is characterized in that component in its composite (B) is 5～6g/10min, contains the ethylene unit of 30～40Wt% in the component (B).

4. hollow container as claimed in claim 1 is characterized in that component in its composite (C) is grafted low density polyethylene acrylic acid.

5. hollow container as claimed in claim 1, the melt flow rate that it is characterized in that component in its composite (B) is 5.5g/10min, the ethylene unit that contains 30Wt% in the component (B), component (C) is a grafted low density polyethylene acrylic acid, its melt flow rate is 1.5g/10min, and percent grafting is 2.0Wt%; The obstruct masterbatch that component (B) and component (C) are made after blend is extruded and the melt viscosity ratio of component (A) are 0.4～0.8.

6. hollow container as claimed in claim 5 is characterized in that the obstruct masterbatch that component in its composite (B) and component (C) are made and the melt viscosity ratio of component (A) are 0.5～0.7 after blend is extruded.

7. the preparation technology of hollow container as claimed in claim 1 may further comprise the steps:

(a) polyethylene and grafted monomers are melt extruded in extruder, extruder control range of temperatures is at 160～210 ℃, screw speed is 150～200RPM, and preparing percent grafting is 1.0～3.0Wt%, and melt flow rate is component (C) compatilizer of 0.5～4.0g/10min;

(b) with component (C) with (B) join melt blending granulation in the double screw extrusion machine in proportion, make the obstruct masterbatch, extruder temperature is controlled at 180～220 ℃, screw speed is 150～200RPM;

(c) will intercept masterbatch then mixed in high-speed mixer 2～5 minutes with component (A), send in the blow molding machine again, at 200～220 ℃ of blow molding high-barrier hollow containers, make in the blowing drawing process extrude the fusion embryo the relative deformation rate at least one direction greater than 100%.