JPH0733066B2 - Heat-shrinkable vinyl chloride resin film - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heat-shrinkable vinyl chloride resin film useful as various container labels, cap seals, packaging materials for integrated products, and the like.

(Prior Art) Conventionally, in heat shrinkable vinyl chloride resin films for the above-mentioned applications, tin film stabilizers such as organotin malate and organotin mercaptide-based plasticizers, plasticizers such as DOP, and M
A composition containing various additives such as an impact resistance agent such as BS, an acrylic processing aid, and a lubricant is used.

However, when the composition is formed into a sheet by calendering or T-die molding in this way and is cooled by a cooling roll to be a raw material for stretching, the heat of molding causes tin-based stabilizers, plasticizers, lubricants, or Vapors of these decomposition products were generated and condensed on the roll surface, which were transferred to the cooling sheet surface to form a thin oil film there.

This is a heat-shrinkable film that is stretched from a raw material, and when it is further processed into tubing, labels, packaging materials, etc., it may cause blocking due to adhesion, locally increase the coefficient of friction of the film, and Was also a cause of blocking due to bleeding of these additives when the films were stacked and stored for a long time.

And, the blocking property and the increase of the friction coefficient also impair the workability in the process such as printing or spine attachment on the heat-shrinkable film, and the feeding and opening of the label in the automatic packaging process of attaching the label to the container. It caused troubles such as hindering movement.

(Problems to be solved by the invention) When the friction coefficient is high in the subsequent steps, a method of spraying a fine powder such as starch or talc in order to improve the slip property (sliding property) of a sheet or film, A method has been proposed in which an inorganic filler such as calcium carbonate or finely powdered silicic acid is added to the mixture in advance and kneaded, but the former method impairs the working environment, and when printing on a film, The latter method has been mainly adopted because the plate roll is easily clogged. However, even in this method, not only the kneading of the inorganic filler fine powder lowers the transparency of the sheet or film, but also the neck-in (the film pulled in the rotating direction of the roll is a roll surface at the time of molding) in the cooling roll part at the time of molding. However, there is a problem in that the thickness unevenness of the original film is increased and the uneven thickness of the shrink film after stretching is increased.

Therefore, an object of the present invention is to reduce the coefficient of friction of the heat-shrinkable film and prevent blocking, and then process the film.
In other words, in the manual or automated process such as film printing, back-pasting, bag making process, container cap sealing, label attachment, packaging for containers and accumulated materials, etc., smooth work and productivity improvement are achieved. Another object of the present invention is to provide a heat-shrinkable vinyl chloride resin film that can be used.

(Means for Solving the Problems) In order to achieve the above-mentioned objects, the present inventors have conducted various studies on additives to be kneaded into the compound of the film raw material, and as a result, adding a silicone resin fine powder is suitable for this purpose. The present invention has been achieved by finding out what is being done.

That is, the present invention, as a heat-shrinkable vinyl chloride resin film, an average particle size of 0.1 to 10 per 100 parts by weight of the vinyl chloride resin.
The gist of the present invention is that a film obtained by blending and molding 0.01 to 10 parts by weight of silicone resin fine particles of μm is stretched.

Hereinafter, the present invention will be described in detail.

First, the vinyl chloride resin used in the present invention is, in addition to a vinyl chloride homopolymer, a vinyl chloride monomer as a main component, and a monomer copolymerizable therewith, such as vinyl acetate,
Also included are copolymers with acrylic monomers such as ethylene, propylene, vinylidene chloride, acrylonitrile.

The vinyl chloride resin is preferably one having an average degree of polymerization of 500 to 1,000 produced by a usual suspension polymerization method. If this is less than 500, the mechanical strength of the heat-shrinkable film obtained will be reduced, and film breakage will easily occur in the post-processes such as the printing process, spine sticking and bag making process, and the average degree of polymerization will exceed 1,000. In that case, the molding processability such as extrusion molding is significantly deteriorated.

On the other hand, the silicone resin fine powder added and blended with the vinyl chloride resin has a general formula [R-SiO _1.5 ] n (wherein R represents an alkyl group or a phenyl group, and n
Is 10 to 1,000) and is a fine powder of silicone resin. This has a very high degree of crosslinking and forms a network structure in which Si-O-Si bonds are three-dimensionally connected. A typical example of this is X-52-590A (Shin-Etsu Chemical Co., Ltd.).
Manufactured, trade name).

The average particle size is 0.1 to 10 μm, and further 0.5 to 5
μm is preferred. If it is less than 0.1 μm, the effect cannot be exhibited unless a large amount of silicone resin fine powder is added, and there is a drawback that the transparency of the film is impaired due to this large amount addition, and if the average particle size exceeds 10 μm, the slipperiness is Although it increases, fine particles can be visually confirmed, and the appearance of the film is impaired.

Addition amount of silicone resin fine powder is vinyl chloride resin 100
It is necessary that the content is 0.01 to 10 parts by weight with respect to parts by weight, and if this is less than 0.01 parts by weight, the effect of the present invention will not be obtained.
If it exceeds the weight part, the molding processability is remarkably deteriorated due to insufficient gelation of the resin in the extruder and neck-in during sheeting. If the amount added exceeds 1 part by weight, the transparency will decrease. Therefore, when transparency is required, the amount added is preferably 0.02 to 0.6 part by weight.

As a method for adding and mixing the silicone resin fine powder to the vinyl chloride-based resin, when the compound of the vinyl chloride-based resin composition is prepared, a method of directly adding it to a high-speed mixer together with other additive materials, and mixing are further preferable. When dispersion is desired, a method of pre-blending with any of the other materials to be mixed and mixing as a masterbatch with a high speed mixer is adopted.

Other additives used in the preparation of this compound include
Plasticizers such as DOA and DOP, impact modifiers such as MBS and ABS, tin stabilizers such as organotin malate and organotin mercaptide, acrylic processing aids such as MMA, lubricants, UV absorbers, and coloring There are agents and the like, and these may be added in desired amounts.

The heat-shrinkable vinyl chloride resin film of the present invention is a compound of such a composition, which is extrusion-molded, is formed into a sheet by calendering, etc., and the obtained sheet is uniaxially stretched in a lateral direction, It can be obtained by selecting longitudinal uniaxial stretching or longitudinal and transverse biaxial stretching, and stretching at a stretching ratio of at least 1.5 to 4.0 in the uniaxial direction.

Hereinafter, specific embodiments of the present invention will be described with reference to examples and comparative examples, but the present invention is not limited to the description of each example without departing from the scope of the invention.

(Example) Silicone resin fine powder X-52-59 was added to the compounding ingredients shown in Table 1.
0A (Shin-Etsu Chemical Co., Ltd., trade name, average particle size 1-2 μ)
m) was added and blended in the proportions shown in Table 2, heated to 120 ° C. in a supermixer, dried up, and then discharged and cooled.

For each of this compounding compound, extruder: D =
65φmm, L / D = 22, screw CR = 3.0, extruder temperature: T die extrusion molding under the conditions of C ₁ = 120 ° C, C ₂ = 150 ° C, C ₃ = 160 ° C, die temperature = 195 ° C from the hopper side. Thickness of 100 μm,
A film having a width of 500 mm was obtained. The condition of neck-in on the surface of the film as it passed through a cooling roll was observed and evaluated according to the following criteria.

The film obtained was preheated to a temperature of 13 with a small tenter.
0 ℃, stretching temperature 90 ℃, heat setting temperature 75 ℃, stretching speed 20m
A heat-shrinkable film was obtained by stretching 2.5 times in the lateral uniaxial direction under the condition of / min. The transparency, the coefficient of friction, and the blocking property of each heat-shrinkable film were measured by the following methods, and the results are shown in Table 2 together with the evaluation results of the neck-in situation.

Test method: 1) Transparency: Hage value is measured according to JIS-K7105.

2) Friction coefficient: Measured according to the ASTM D-1984-74 method.

3) Blocking property: The obtained heat-shrinkable film is cut into a size of 25 cm × 30 cm, and 6 pieces of each are stacked. This is pressed at a temperature of 25 ° C. at a pressure of 50 kg / cm ² for 5 minutes by a press. After pressing, the sample was taken out and the blocking state was compared and observed by the peelability of the film, and evaluated according to the following criteria.

-Evaluation Criteria x: A blocking state is observed on the entire surface, and the film is difficult to peel off.

Δ: A state in which the film surface is half blocked is observed, and the blocked film is not peeled even if it is placed vertically.

◯: No blocking on the film surface is observed, but 1/3 is peeled off when the film is set upright.

⊚: No blocking state was observed on the film surface,
Completely peels off when the film is set upright.

4) Evaluation criteria for neck-in situation: X: Neck-in is significantly generated, and the width of the extruded film is not determined at all.

Δ: Neck-in sometimes occurs remarkably.

◯: A slight neck-in occurs, but it does not hinder the production of a film with a width of 500 mm.

A: Neck-in does not occur at all.

(Effects of the Invention) The heat-shrinkable vinyl chloride resin film according to the present invention has a reduced friction coefficient and improved blocking property as compared with the conventional ones, and therefore, the film printing, backing, bag making process, container It is possible to achieve smoothness of work in a manual process or an automated process and improvement of productivity in post-processing such as mounting a cap seal, a label, etc. on a container, packaging for a container, an integrated material, etc.

Claims (1)

[Claims] 1. An average particle size of 0.1 per 100 parts by weight of vinyl chloride resin.
A heat-shrinkable vinyl chloride resin film formed by stretching and stretching a film containing 0.01 to 10 parts by weight of silicone resin fine particles of -10 μm.