WO1990001409A1 - Procede de production d'un film de polyethylene thermoretractable - Google Patents

Procede de production d'un film de polyethylene thermoretractable Download PDF

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Publication number
WO1990001409A1
WO1990001409A1 PCT/JP1989/000142 JP8900142W WO9001409A1 WO 1990001409 A1 WO1990001409 A1 WO 1990001409A1 JP 8900142 W JP8900142 W JP 8900142W WO 9001409 A1 WO9001409 A1 WO 9001409A1
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WO
WIPO (PCT)
Prior art keywords
temperature
film
expansion
heat
stretching
Prior art date
Application number
PCT/JP1989/000142
Other languages
English (en)
Japanese (ja)
Inventor
Hideo Isozaki
Tomozi Mizutani
Yoshihiro Sakamoto
Original Assignee
Kohjin Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from PCT/JP1988/000807 external-priority patent/WO1989001402A1/fr
Application filed by Kohjin Co., Ltd. filed Critical Kohjin Co., Ltd.
Publication of WO1990001409A1 publication Critical patent/WO1990001409A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/28—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of blown tubular films, e.g. by inflation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C61/00—Shaping by liberation of internal stresses; Making preforms having internal stresses; Apparatus therefor
    • B29C61/003—Shaping by liberation of internal stresses; Making preforms having internal stresses; Apparatus therefor characterised by the choice of material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C61/00—Shaping by liberation of internal stresses; Making preforms having internal stresses; Apparatus therefor
    • B29C61/06—Making preforms having internal stresses, e.g. plastic memory
    • B29C61/08—Making preforms having internal stresses, e.g. plastic memory by stretching tubes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/06—PE, i.e. polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037—Other properties
    • B29K2995/0049—Heat shrinkable
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/04—Homopolymers or copolymers of ethene
    • C08J2323/08—Copolymers of ethene

Definitions

  • the present invention relates to a shrink wrapping material, and more specifically, a thickness mainly composed of ethylene and ⁇ -olefin copolymer having a parameter g ′ of 0.3 to 0.7 indicating direct molecular chain resilience.
  • the present invention relates to a method for producing a heat-shrinkable film having small spots and excellent transparency and low shrinkage.
  • This biaxially oriented biaxially stretched film has been used practically because it has heat sealing properties and is inexpensive.
  • a linear low-density copolymer of ethylene and ⁇ -olefin hereinafter simply referred to as linear Polyethylene-based heat-shrinkable films using low-density polyethylene have attracted attention because of their excellent impact resistance and heat seal strength.
  • the present inventors have studied a method for producing a polyethylene-based heat-shrinkable film which is excellent in low-temperature shrinkage with a small thickness unevenness using the above-mentioned resin having excellent transparency.
  • the temperature at the expansion point (start point) is set to the melting point of the resin composition (the endothermic main beak in the melting curve obtained by measurement with a differential scanning calorimeter (hereinafter abbreviated as DSC)).
  • DSC differential scanning calorimeter
  • the maximum temperature should be set at 1 Z4 to 1/3 of the distance of the stretching zone from the start point of expansion to the end point of expansion, with the difference between the maximum temperature and the film surface temperature at the start point of expansion. Is less than or equal to 5,
  • a method for producing a polyethylene-based heat-shrinkable film having a small thickness unevenness, excellent low-temperature heat-shrinkability, and excellent transparency At this time, the endothermic area of the resin composition, which is obtained by measuring with a differential scanning calorimeter (hereinafter abbreviated as “DSC”) a temperature lower than the melting point (endothermic main peak) by 10 or less, is preferably the total endothermic area
  • DSC differential scanning calorimeter
  • the present invention relates to a method for producing a polyethylene-based heat-shrinkable film, which is characterized by being 55% or more.
  • FIG. 1 is a conceptual diagram of a tumbler stretching device used in the present invention.
  • FIG. 2 is an enlarged view of an extended portion of FIG. BEST MODE FOR CARRYING OUT THE INVENTION
  • the resin cord composition used in the present invention is a resin mainly composed of a linear low-density polyethylene or a combination of ethylene and an ⁇ -olefin having at least 4 to 12 carbon atoms.
  • the shrinkage at low temperature is not sufficient. If the density is less than 0.86 g cm 3 , the anti-blocking agent such as inorganic fine particles is too soft or too blocky. Even if used together, it cannot be improved sufficiently.
  • the resin cord composition used in the present invention is mainly composed of linear low-density borylene as described above, and the melting point (endothermic main beak) in the melting curve measured using DSC is particularly important.
  • 1) the ratio of the endothermic area below TC lower than ⁇ to the total endothermic area (hereinafter abbreviated as endothermic area ratio) is 55% or more), because it has excellent stretching stability over a relatively wide range of ⁇ °. Particularly preferred.
  • a method of obtaining a melting curve by the above differential scanning calorimeter (in the present invention, a differential thermal analysis and concealment device (DSC-200) manufactured by Seiko Denshi Kogyo KK) is used. First, 6 to 8 mg of a sample is sealed in an aluminum van. Then, the temperature was raised to 190 ° C in a stream of nitrogen, maintained at this temperature for 1 hour, and then cooled to room temperature at a rate of about 10 / min. The melting point and the endothermic area ratio are determined from the DSC chart obtained by ascending.
  • DSC-200 differential thermal analysis and concealment device manufactured by Seiko Denshi Kogyo KK
  • Examples of the ⁇ -olefins having 4 to 12 carbon atoms copolymerized with ethylene include putene-11, pentene-11, hexene1-1, hebutin-11, octin-1,1,4-methylpentene1-1, Decene-1, Dedecene-1, Dodecene-1 Are exemplified.
  • the copolymerization ratio of ⁇ -olefin used in the copolymerization is preferably 0.5 to 10 mol%.
  • high-pressure polyethylene in addition to the above-mentioned linear low-density polyethylene, if desired, high-pressure polyethylene, an ethylene monoacetate vinyl copolymer, an ionomer, and an ethylene propylene copolymer may be used as long as the object of the present invention is not hindered.
  • Additives such as polymers such as ethylene-based polymers, lubricants, anti-booking agents, and antistatic agents can be used in combination.
  • FIGS. 1 and 2 a method for producing a heat-shrinkable polyethylene film by the method of the present invention will be described with reference to FIGS. 1 and 2.
  • Fig. 1 is a conceptual diagram of the tubular extension equipment
  • Fig. 2 is an enlarged view of the extension.
  • the tubular unstretched film used in the present invention can be produced by melt-extruding the above-mentioned resin cord (hereinafter simply referred to as a resin composition) by a known method, and rapidly solidifying it.
  • the unstretched film obtained in this way is supplied to, for example, a stretching device as shown in Fig. 1, and when bubbles are generated by injecting air into the tube between nibroll 2 and nibroll 3, expansion and stretching are performed. Adjust the temperature so that the temperature at the expansion start point 101 is within the melting point of the resin (the main beak of the DSC chart) and the temperature range of 20 to 3 below. This can be performed by adjusting the cooling device 6. If the temperature at the expansion start point is higher than the above range, the film near the expansion start point is too soft, the stretching tension is reduced, and the film expands abnormally, resulting in uneven stretching. In addition, the orientation effect due to stretching is reduced, and the strength and heat shrinkage of the stretched film are lowered, which is not preferable.
  • the expansion starting point is defined as L when the length of the stretching zone from the expansion start point 101 to the expansion end point 103 is L.
  • An upward temperature gradient is set so that the temperature at which LZ has progressed from LZ 4 to 3/3 reaches the maximum temperature, and the difference between the maximum temperature and the expansion / starting point temperature is within 5 digits.
  • the temperature at the expansion end point 103 should be 15 to 20 ° C lower than the maximum temperature, and during the travel of a distance of 0.8 times the length L of the stretching zone from the expansion end point. 6 (Cool to below TC.
  • the above-mentioned maximum temperature exceeds a temperature 5 ° C higher than the temperature at which the expansion starts, the tensile strength of the film decreases, the thermal shrinkage of the resulting film decreases, and bubble expansion becomes unstable, resulting in unstable rocking. Conversely, if the temperature gradient is lowered during LZ 4 to 3/3 after passing through the expansion starting point 101, the stability of the stretched bubble will be improved, but the stretch will proceed in a balanced vertical and horizontal direction. In any case, the thickness unevenness of the obtained stretched film becomes large, and the object of the present invention cannot be sufficiently achieved.
  • the temperature drop between the maximum temperature point 102 and the stretching end point 103 is 15 and the size is smaller, the bubbles become unstable and the thickness unevenness becomes larger, which is not preferable.
  • the temperature drop is set so as to exceed 20, the internal pressure of the bubble will increase abnormally and the stability of the expansion starting point 101 will be lost, and the upper portion of the bubble will easily roll and the thickness unevenness will increase, which is preferable. Absent.
  • the bubble in order to stabilize the bubble, it is preferable to cool rapidly even after reaching the expansion end point 103. In other words, it is rapidly polished so as to be 60 or less while traveling a distance of 0.8 times the length L of the stretching zone from the expansion end point. If not rapidly cooled in this manner, the entire bubble is likely to sway, and the sway causes local unevenness in stretching, thereby increasing the thickness unevenness of the obtained film.
  • the resin with a relatively small g * value of 0.3 to 0.7 has excellent transparency, but in the case of the conventionally known linear low-density polyethylene, Under the same conditions as described above, stable bubble-like stretching was difficult, but by applying the method of the present invention, it was possible to obtain a film with stable stretching, small thickness unevenness, and excellent practicality. It has become.
  • a and A ' are the average values of the two sides of the measured values before and after contraction, respectively.
  • the temperature of the film during the stretching process is about lmm in diameter and about 15 exposed parts in length.
  • the ratio of the scattered light transmittance to the parallel light transmittance was shown as a percentage using an integrating sphere light transmittance measuring device based on JIS-K6714.
  • [7] is the intrinsic viscosity of the polyethylene copolymer to be measured, and decalin is used as the solvent135. Determined by dissolving in C.
  • [ ⁇ ] L is the limiting viscosity of linear polyethylene having the same weight average molecular weight as the polyethylene copolymer of the above sample. This value is the weight average molecular weight ⁇ M> w measured by the light scattering method. Can be obtained from the following equation by an approximate calculation.
  • Linear polyethylene copolymer resin of ethylene and Okuten one 1 (8: 'is 0.5 9, melting point 125.C, density at 25.C is 0. 915 g / cm 3, Merutoinde box 1.0) It was melt-extruded from a tubular die with a diameter of 66 and rapidly cooled by internal and external water cooling to obtain a tubular unstretched film with a diameter of 65 mm and a thickness of 370. The endothermic area ratio of the unstretched film resin measured by DSC was 58.9%. The obtained unstretched film is fed to a tubular stretching machine running in the vertical direction as shown in Fig.
  • the vertical distance L in the stretching zone was about 21 cm
  • the outer diameter of the baples was 240 cm
  • the point of highest film temperature was about 6. Ocm below the starting point of the expansion.
  • the biaxially stretched film was guided to another tube-shaped annealing apparatus whose temperature was adjusted to another 70, annealed for 10 seconds, cooled to room temperature, folded again, taken out and wound up.
  • a linear polyethylene copolymer resin of ethylene and honored-1 (8 ⁇ 0.65: melting point: 18.7, density at 25 ° C: 0.906'grZcm 3 , melt index: 0.8) was the same as in Example 1.
  • a tubular unstretched film with a diameter of 65 mm and a thickness of 359 i was obtained.
  • the endothermic area ratio of the unstretched film resin measured by DSC was 53%.
  • a stretched bubble was formed from the obtained unstretched film in the same manner as in Example 1, and a biaxially stretched film could be stably manufactured at 13 m / min for a long time under the conditions shown in Table 1.
  • the vertical distance L in the stretching zone was about 20.5 cm
  • the outer diameter of the baples was 25 Omm
  • the point of maximum film angle was about 5.8 cm below the point of expansion.
  • the biaxially stretched film was guided to another tubular annealing device whose temperature was adjusted to 70, and after annealing for 10 seconds, cooled to room temperature, folded again, taken out and wound.
  • a stretch bubble was formed from the obtained unstretched film in the same manner as in Example 1, and a biaxially stretched film could be stably manufactured at 15 mZ for a long time under the conditions shown in Table 1.
  • the vertical distance L in the stretching zone was about 20.2 cm, the outer diameter of the bubble was 250 strokes, and the point of maximum film angle was about 5.4 cm below the starting point of expansion.
  • This biaxially stretched film was guided to another tube-shaped annealing apparatus whose temperature was adjusted to another 70, and after annealing for 10 seconds, cooled to room temperature, folded again, taken out and wound up.
  • a linear polyethylene copolymer resin of ethylene and butene-11 ( ⁇ : ⁇ 0.89, melting point 122, 25, density 0.923 g / cm 3 , melt index 0.8) was the same as in Example 1.
  • a tubular unstretched film with a diameter of 65 mm and a thickness of 366 was obtained.
  • the endothermic area ratio of the unstretched film resin measured by DSC was 63.8%.
  • a stretched bubble was formed from the obtained unstretched film in the same manner as in Example 1, and a biaxially stretched film could be stably manufactured at 16 mZ for a long time under the conditions shown in Table 1.
  • the vertical distance L in the stretching zone was about 21. Ocm, the outside diameter of the tuple was 241 mm, and the point of maximum temperature of the film was about 6.2 cm below the starting point of expansion.
  • the film was guided to another 7 CTC tube annealing device, and after annealing for 10 seconds, it was cooled in the room, folded again, taken out and wound up.
  • the thickness, uneven thickness, haze, and heat shrinkage of the obtained film were measured, and the results are shown in Fig.1.
  • Linear Boriechiren copolymer resin of ethylene and Okuchin one 1 (g 'to zero. 9 2, melting point 1 2 6, density at 2 5 0.9 2 g / cm 3, a melt-in deck scan 1.0) to In the same manner as in Example 1, a tubular unstretched film having a diameter of 65 mm and a thickness of 366 was obtained.
  • the endothermic area ratio of the unstretched film resin measured by DSC was 59.4%.
  • a stretched bubble was formed from the obtained unstretched film in the same manner as in Example 1, and a biaxially stretched film was produced at 15 mZ under the conditions shown in Table 1. As a result, the bubble stability was somewhat insufficient. The obtained film had a large thickness unevenness.
  • the vertical distance L in the stretching zone was about 21.O cra, the outer diameter of the bubble was 234 mm, and the point of the highest temperature of the film was about 6.2 cm below the expansion start point.
  • This film was guided to another tube-shaped annealing apparatus whose temperature was adjusted to 70, annealed for 10 seconds, cooled to room temperature, folded again, taken out and wound up.
  • a tubular unstretched film having a thickness of 370 was obtained in the same manner as in Example 1 except that the same linear low-density polyethylene as in Example 1 was used as the resin.
  • the unstretched film was set to a temperature higher than the temperature range specified in the method of the present invention except that the temperature at the starting point of expansion and the temperature at the highest temperature point were higher than the temperature range specified in the method of the present invention as shown in the condition of No.
  • a biaxially stretched film was produced at 16 m / min. During production, the bubble was abnormally expanded and unstable, and could not be manufactured continuously for a long time.
  • Example 2 Using the same linear low-density polyethylene as in Example 1 as a resin, a tubular unstretched film having a thickness of 370 X was obtained in the same manner as in Example 1.
  • the unstretched film was subjected to the same procedure as in Example 1 except that the temperature at the expansion start point and the temperature at the highest temperature point were lower than the temperature range specified in the method of the present invention.
  • a tubular unstretched film having a thickness of 360 // was obtained in the same manner as in Example 2 except that the same linear low-density polyethylene as in Example 2 was used as the resin.
  • This unstretched film was subjected to tubular stretching in the same manner as in Example 2 except that the cooling after passing through the expansion end point was insufficient as shown in Table 1. However, the nople rocked and could not maintain stable stretching.
  • the heat-shrinkable film produced as described above which has a small thickness unevenness, has excellent uniformity as a film, so that it can be handled smoothly in the laminating process and packaging process with other films, and Because of its excellent transparency and heat sealability due to the physical properties of the material, it can be used as an extremely excellent packaging material.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)

Abstract

Film de polyéthylène thermorétractable présentant de faibles irrégularités d'épaisseur et d'excellentes caractéristiques de thermorétractabilité à faible température et de transparence, ne pouvant être obtenu par le procédé connu d'étirement biaxial tubulaire d'un polyéthylène linéaire de faible densité présentant un g. dont la valeur est comprise entre 0,3 et 0,7 (g.=[n].[n]¿L?, où [n] est une viscosité limite d'un polymère à chaîne droite présentant le même poids moléculaire moyen que le polymère précédent). On produit ce film en sélectionnant une résine contenant comme composant principal un copolymère composé d'éthylène et de 1 à 10 % d'au moins une α-oléfine comportant de 4 à 12 C et présentant un indice de fusion compris entre 0,3 et 2,0 g/10 min et une densité à 25°C comprise entre 0,86 et 0,92 g/cm?3¿, de préférence une composition présentant une superficie endothermique égale ou supérieure à 55 % par rapport à la totalité de la superficie endothermique au-dessus du point de fusion dans une courbe de fusion que l'on obtient grâce à un calorimètre à balayage différentiel, et en effectuant un étirement tubulaire à une température d'étirement spécifique.
PCT/JP1989/000142 1988-08-15 1989-02-13 Procede de production d'un film de polyethylene thermoretractable WO1990001409A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
USPCT/JP88/00807 1988-08-15
PCT/JP1988/000807 WO1989001402A1 (fr) 1987-08-14 1988-08-15 Procede de production d'un film de polyethylene thermoretractable

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WO1990001409A1 true WO1990001409A1 (fr) 1990-02-22

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0359907A2 (fr) * 1988-09-21 1990-03-28 Kohjin Co., Ltd. Procédé pour fabriquer des films en polyéthylène thermorétractables

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57181828A (en) * 1981-04-23 1982-11-09 Du Pont Shrinkable film of ethylene/alpha- olefin copolymer
JPS6445622A (en) * 1987-08-14 1989-02-20 Kohjin Co Manufacture of polyethylene-based heat-shrinkable film

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57181828A (en) * 1981-04-23 1982-11-09 Du Pont Shrinkable film of ethylene/alpha- olefin copolymer
JPS6445622A (en) * 1987-08-14 1989-02-20 Kohjin Co Manufacture of polyethylene-based heat-shrinkable film

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0359907A2 (fr) * 1988-09-21 1990-03-28 Kohjin Co., Ltd. Procédé pour fabriquer des films en polyéthylène thermorétractables
EP0359907A3 (fr) * 1988-09-21 1992-03-11 Kohjin Co., Ltd. Procédé pour fabriquer des films en polyéthylène thermorétractables

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