JP2000044745A5 - - Google Patents

Description

0003
[Conventional technology]
A method of producing a film by inflating polystyrene is widely used. But film prepared using conventional polystyrene resins generally for take-off speed at the time of film formation is large, easily takes stretched in MD, in extension Shin magnification imbalance between TD, the tensile elongation of the film MD, TD anisotropy is large. Therefore, there is a problem that film breakage is likely to occur when printing on a film after film formation or when the film is bonded to expanded polystyrene (polystyrene paper) or the like for secondary processing .
As a method of eliminating this MDTD anisotropy, there is a method of reducing the extrusion amount of the resin and lowering the take-up speed, but this is not realistic because it lowers the productivity. Further, as a method of increasing the tensile elongation of TD of a polystyrene-based film, there is a method of increasing the ratio of styrene-butadiene block copolymer, but there is a limit because it leads to an increase in cost and the blocking of the obtained film becomes severe. there were.

0004
[Problems to be Solved by the Invention]
An object to be solved by the present invention is to provide a film having an excellent balance of physical properties between the film winding direction (MD) and the direction perpendicular to the film take-up in the film plane (TD).

0005
[Means for solving problems]
That is, the first invention of the present invention is a blown film comprising a styrene resin composition comprising the following components (A) and the following component (B), when immersed for 3 minutes in a silicone oil bath at 120 ° C. The shrinkage rate of both MD and TD is 2% to 90%, and the ratio of the shrinkage rate of MD to TD (MD / TD) is 0.2 to 30. It relates to a small inflation film.
(A) Styrene-based resin with a weight average molecular weight of 100,000 to 2,000,000 99.000 to 99.998% by weight
(B) Fine particles 1.000 to 0.002% by weight having a refractive index of 1.5 to 2.0, an average particle size of 0.1 to 20 μm, and a glass transition temperature equal to or higher than the glass transition temperature of the styrene resin, or no glass transition.
The second invention of the present invention relates to the inflation film in which the styrene-based resin composition further has a weight average molecular weight of 100,000 to 500,000 and contains 60% by weight or less of a styrene-butadiene block copolymer. It is a thing.

Those related to the inflation film is an inorganic antibacterial agent in which the inorganic antimicrobial agent was responsible lifting silver or zinc.

0009
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
Styrene resin used in the present invention, measured by differential angle refractive index detection method by gel Pas chromatography permeation chromatography, the weight average molecular weight relative to the linear standard polystyrene 100,000 2,000,000 preferably 100,000 ~ 500,000. If the molecular weight is too small, the impact strength is inferior, while if the molecular weight is too large, the fluidity is inferior. As the polymerization method, a batch suspension polymerization method or a continuous bulk polymerization method can be used, and either a thermal polymerization method or a polymerization method using an initiator can be used.

Examples of a monomer constituting the styrene resin, styrene, alpha-methyl styrene, such as alpha - substituted alkyl styrene, nucleus-substituted alkylstyrenes such as p- methylstyrene, also together with the styrene compound, styrene compound copolymerizable Possible compounds include vinyl monomers such as ester derivatives such as acrylonitrile, methacrylonitrile, methacrylic acid, methyl methacrylate, as well as maleic anhydride, maleimide, nuclear-substituted maleimide and the like.

The styrene resin composition of the present invention has a refractive index of 1.5 to 2.0, preferably 1.5 to 1.7, an average particle size of 0.1 to 20 μm, preferably 0.1 to 5 μm, and is equal to or higher than the glass transition temperature of the styrene resin. or a glass transition temperature, or fine particles which do not exhibit a glass transition 0.002 wt%, preferably not containing 0.01-0.5 wt%. Such Preferred examples of the fine particle element, calcium phosphate satisfying the above condition, barium sulfate, talc, crosslinked polystyrene beads, zeolites, and the like. Further, an inorganic antibacterial agent in which Ag or Zn is supported on fine particles such as silica-based, alumina-based, zeolite-based, and glass-based is included.

If the range of the refractive index of the fine particles is smaller or larger than 1.5 to 2.0, the properties of the film are inferior. When the average particle size and the content ratio of the fine particles are excessive, the surface condition of the obtained inflation film becomes extremely rough and deteriorates, and the appearance and transparency are deteriorated. If it is too small, the balance of tensile physical properties between MD and TD of the obtained inflation film is not good.

The refractive index of the fine particles is measured by, for example, the following method. That is, sandwiched between a slide glass fine particles dispersed in the solution refraction index is known, and observed with a polarizing microscope, a method of obtaining as compared to the refractive index of the solution, for details, for example the book "polarizing microscope How to use "(Kenya Hamano, Gihodo).

The glass transition temperature of the microparticles can be determined by measuring the differential heat by differential scanning calorimetry (DSC), for example PERKINELMER (Pas over kin Elmer) Inc. Model 7700 DSC apparatus. Details are described in, for example, the book "New Experimental Chemistry Course 2 (3. Thermal Analysis Measurement)" (edited by The Chemical Society of Japan, published by Maruzensha, 1984, pp. 87-122).

The styrene- butadiene block copolymer used in the present invention is a kind of styrene-based thermoplastic elastomer, for example, by anionic polymerization using alkyllithium represented by n-butyllithium as a polymerization initiator and cyclohexane as a solvent. It is synthesized. Although various forms are possible depending on the synthetic method, it is basically SBS-based (polystyrene - polybutadiene - polystyrene). Most of them have a weight average molecular weight of less than 200,000 in terms of polystyrene. The butadiene content in this styrene-butadiene copolymer is preferably 35% by weight or less. If it is 35% or less, the transparency and rigidity of the film after film formation are good.

Styrene styrene resin composition used in the present invention - by containing butadiene block copolymer, it is possible to increase overall the tensile elongation properties of the film. However styrene - content of butadiene block copolymer is preferably in the resin composition 60 wt% or less, more preferably 10 to 30 wt%. When the content ratio is 60% by weight or less, the blocking property of the inflation film is low and the films do not adhere to each other.

In the method for producing an inflation film of the present invention, a blended resin composition of the present invention is passed through a screw heated to 160 ° C. to 230 ° C., preferably 160 to 200 ° C. using an extrusion processing machine, and a circular die is attached. A method of continuously producing a cylindrical film with a thickness of 100 μm or less with a diameter larger than the die diameter by immediately inflating it with air pressure, folding it, and winding it while taking up the molten resin extruded into a tube shape from the extruder in the vertical direction. is there. The thickness and stretchability of the film are adjusted by the screw rotation speed, the take-up speed, and the degree of expansion by air pressure. The film after the inflation process may be a biaxial extension Shin film over the further stretching in the TD at 100 to 150 ° C..

Blown film using the resin composition of the present invention, the laminate film of the expanded polystyrene being used as instant noodle containers (Indianapolis Ji Ren paper), can be effectively used in applications such as for vegetables packaging film.

(1) a circular to cut the film shrinkage diameter 65mm film, to immersion in a silicone oil bath heated to 120 ° C., and taken out after 3 minutes to measure the length of the diameter of the MD and TD. Each shrinkage rate value is calculated by the following formula.
Shrinkage rate (%) = ((XY) / X) x 100 X: Length before immersion in silicone oil bath (65 mm)
Y: Length after soaking and taking out.

Example 1
Obtained by continuous bulk polymerization, pellet-shaped GPPS (Nippon Polystyrene Co., Ltd., trade name: Nippon Porisuchi G757X) 89.95 wt%, HIPS (Nippon Polystyrene Co., Ltd., trade name: Nippon Porisuchi H640) 10 After thoroughly mixing 0.05% by weight of barium sulfate fine particles with a refractive index of 1.64 and an average particle size of 2.5 μm, the resin temperature is adjusted using a 40φ inflation processing machine (die diameter 75φ) manufactured by PLACO Co., Ltd. The film was processed under the conditions of 220 ° C. and a die temperature of 200 ° C. The screw rotation speed at the time of extrusion was fixed at 30 rpm, and the take-up speed was adjusted so that the film width was 23 cm and the film thickness was 25 μm.

Example 2
Obtained by continuous bulk polymerization, pellet-shaped GPPS (Nippon Polystyrene Co., Ltd., trade name: Nippon Porisuchi G637) 74.7 wt%, HIPS (Nippon Polystyrene Co., Ltd., trade name: Nippon Porisuchi H640) 10 wt%, a styrene-butadiene copolymer (full I Lips oil Co., Ltd., trade name: K resin KR-05) 15 wt%, and silver zeolite-based antimicrobial agent particles (Kanebo Kasei Co., Ltd., trade name: After sufficiently mixing 0.3% by weight of (bactekiller), film processing was performed under the conditions of a resin temperature of 220 ° C. and a die temperature of 200 ° C. using a 40φ inflation processing machine (die diameter 75φ) manufactured by Placo Co., Ltd. The screw rotation speed at the time of extrusion was fixed at 60 rpm, and the take-up speed was adjusted so that the film width was 23 cm and the film thickness was 25 μm. The antibacterial property of the film obtained in this experiment was good.

Comparative Example 3
Using a V65-1000 sheet extruder manufactured by Tanabe Plastic Machinery Co., Ltd., the resin composition used in Example 1 was used, a resin temperature of 220 ° C., a screw rotation speed of 300 rpm, a T-die lip clearance of 1.0 mm, a lip width of 900 mm, and the like. A sheet having a thickness of 0.3 mm (300 μm) was formed at a roll temperature of 90 ° C., a second roll temperature of 60 ° C., and a take-up speed of 2.75 m / min. The shrinkage rate in the TD direction was -0.2%, and the T-die method could not obtain a shrinkage rate in the TD direction.

Claims (5)

A blown film composed of a styrene resin composition containing the following component (A) and component (B) below, and the shrinkage when immersed in a silicone oil bath at 120 ° C. for 3 minutes shows the film winding direction (MD ) And the direction perpendicular to the film take-up direction (TD) in the film plane is 2% to 90%, and the shrinkage ratio of MD and TD (MD / TD) is 0.2 to 30 An inflation film having a small tensile elongation anisotropy.
(A) 99.000 to 99.998% by weight of a styrene resin having a weight average molecular weight of 100,000 to 2 million
(B) Fine particles having a refractive index of 1.5 to 2.0, an average particle size of 0.1 to 20 μm, and exhibiting a glass transition temperature equal to or higher than the glass transition temperature of the styrenic resin or not exhibiting a glass transition 1.000 to 0.002% by weight The inflation film according to claim 1 , wherein the styrene-based resin composition further has a weight average molecular weight of 100,000 to 500,000 and contains a styrene - butadiene block copolymer in an amount of 60% by weight or less in the resin composition. The inflation film according to claim 1 or 2 , wherein an inorganic antibacterial agent is used as the fine particles. Blown film according to claim 3 inorganic antibacterial agent is an inorganic antibacterial agent was responsible lifting silver or zinc. The inflation film according to claim 3 or 4 , which is used for food packaging .