JPH031349B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a film with improved blocking properties, and more particularly to a film with improved blocking properties and slipperiness without impairing transparency by adding glass powder. Today, transparent synthetic resin films are widely used for various packaging bags, covers, wraps, etc. These films have excellent transparency and surface gloss, which makes the contents look beautiful and increase the product value. However, because the surface is smooth, films tend to stick to each other (a phenomenon called blocking). ), it also has the disadvantage of being difficult to use. In order to improve this blocking, inorganic fine powder such as silicon dioxide or calcium carbonate is added to form some surface irregularities to prevent blocking. However, since these inorganic fine powders have the disadvantage of impairing transparency, it is not possible to increase the amount added. In addition, since it is made very fine to prevent a decrease in transparency, it has poor dispersibility and is prone to agglomeration, and it also adsorbs other additives such as antistatic agents and slipping agents, resulting in antistatic and slippery properties. However, quality design was difficult, and it was not possible to satisfy all performance requirements at the same time. The present invention provides an antiblocking agent that solves these problems. In other words, by adding glass with a refractive index that matches the base transparent synthetic resin in the form of fine powder, the transparency will not decrease when it is made into a film, and
The purpose of this invention is to provide a technology that achieves a sufficient anti-blocking effect without interfering with the effects of other additives. The transparent synthetic resin used in the present invention may be any transparent resin that can be formed into a film, such as polyethylene, polypropylene, polyolefin such as ethylene-biacetate copolymer, polyester, polyamide, polyvinyl chloride, polyvinyl alcohol, etc. can be given. In the present invention, glass is a material whose main component is silicon dioxide, 5 to 80 mol% of silicon dioxide, 1 to 50 mol% of alkali metal oxides, 0 to 40 mol% of alkaline earth metal oxides, and Al ₂ O. ₃ , _{B2O3 , P2O5 ,}
A glassy material containing a total of 0 to 50 mol % of one or more oxides selected from ZnO, TiO ₂ or Bi ₂ O ₃ is used. Here, silicon dioxide forms the framework of the glass structure as the main component, and aluminum oxide improves the chemical durability of the glass. Other components assist in glass formation and have effects such as adjusting the refractive index and making the glass brittle so that it can be easily ground into fine powder. This glass is made into a fine powder so that it can be easily added to the resin, and its average particle size is 50μ or less, preferably 20μ or less. Further, if it is less than 1μ, the anti-blocking effect will be small, so it is desirable that at least half of the weight ratio is 1μ or more. As for the surface area of the glass powder, it is preferable that it is small in order to prevent adsorption of other additives, and the surface area per glass weight is 50 m ² /g or less, preferably 5 m ² /g.
It is powdered to a weight of less than 100 g. These powders sometimes contain paraffin,
The powder may be treated with a surface treatment agent such as a fatty acid, a polyhydric alcohol, or a silane coupling agent, and the dispersibility of the powder into a synthetic resin will be improved. The amount of glass fine powder added in the present invention varies depending on the type of resin and the method of forming into a film, but
Generally, based on the total amount of synthetic resin and glass fine powder, 0.05% by weight or more and less than 1.0% by weight, preferably 0.2% by weight or more and less than 1.0% by weight is added, and this is often the case for resin compositions that are prone to blocking. In contrast, smaller amounts of finer powder are used in stretched films and the like. Conventional antiblocking agents are generally used to reduce transparency and adsorption of other additives.
However, the fine glass powder of the present invention has less effect on other properties, so it has less blocking prevention properties. The amount necessary for prevention can be added, and the amount added can be reduced in order to obtain the same anti-blocking performance. This is because it is possible to select the particle size that is most effective in preventing blocking without substantially affecting transparency. Molding in the present invention can be carried out by various methods. The glass fine powder according to the present invention may be directly added to a transparent synthetic resin along with other additives if necessary and molded, or it may be formed into a highly concentrated masterbatch and then diluted with resin and molded. . As the film molding method, known molding methods such as inflation molding, T-die molding, biaxial stretching molding, and calendar molding can be used. The film of the present invention prevents blocking, has good transparency, and has excellent effects when combined with antistatic agents and slip agents, so it can be used for various purposes. For example, when used as packaging bags for food or clothing, blocking is prevented, so filling operations can be carried out smoothly, and since the effects of antistatic agents and slip agents are not inhibited, there is less electrostatic adhesion and slippage. Good quality and transparency can increase product value. Furthermore, by using it in films that are difficult to prevent blocking, such as ethylene vinyl acetate copolymers, blocking can be effectively prevented. Next, the present invention will be explained using Examples, but the present invention is not limited thereto. Example 1 Glass composition is 35 mol% of SiO ₂ , 5 mol% of Al ₂ O ₃ ,
P ₂ O ₅ 15 mol%, Na ₂ O 20 mol%, MgO 15 mol%,
Prepare fine glass powder containing 10 mol% ZnO and having an average particle size shown in Table 1, add it to low density polyethylene (Yukalon ZF-51 manufactured by Mitsubishi Yuka) at varying concentrations, and make a film with a thickness of 50μ by inflation. Molded by method.

[Table] The refractive index of this glass was 1.50, and the refractive index of low density polyethylene was 1.51. Example 2 The fine glass powder (b) of Example 1 was mixed with ethylene vinyl acetate copolymer (Yukalon Eva manufactured by Mitsubishi Yuka Co., Ltd.).
EVA41H) was added in an amount of 0.9% by weight, and a film with a thickness of 100μ was obtained by inflation molding. Note that the refractive index of this ethylene vinyl acetate copolymer was 1.50. Example 3 0.2% by weight of the glass fine powder (c) of Example 1 was added to polypropylene (Noblen FL6 manufactured by Mitsubishi Yuka Co., Ltd.) and a film with a thickness of 30 μm was obtained by biaxial stretching. Note that the refractive index of polypropylene was 1.49. Comparative Example 1 Silicon dioxide, calcium carbonate, and fine powder having the particle sizes shown in Table 2 were added to the low-density polyethylene of Example 1, and a film having a thickness of 50 μm was formed by an inflation method.

[Table] The refractive index of silicon dioxide was 1.45, and the refractive index of calcium carbonate was 1.60. Comparative Example 2 The fine powder (e) used in Comparative Example 1 was added to the ethylene vinyl acetate copolymer used in Example 2 at 0.3% by weight and 0.9% by weight.
A film with a thickness of 100 μm was obtained in which % by weight of each was added. Comparative Example 3 Using the fine powder (d) used in Comparative Example 1, 0.1% by weight and 0.2% by weight of polypropylene were added as in Example 3 to obtain a biaxially stretched film. Table 3 shows the haze and blocking properties of each film.
Shown below. From Table 3, it is clear that the present invention has excellent blocking prevention and transparency. In addition, blocking property is measured by making two strips of film 2 cm wide, stacking them 5 cm long, applying a load of 50 g/ ^cm2 , leaving them at 40°C for 24 hours, and then reading the load when shearing and peeling with a tensile tester. I evaluated it. The lower the number, the better. Example 4, Comparative Example 4 The materials used in Example 3 and Comparative Example 3 were added at a concentration of 0.3% by weight, and alkylamine (manufactured by Lion Armor, Amostat 310) was added as an antistatic agent.
A film made by biaxial stretching was prepared by adding 0.2% by weight of stearic acid amide and 0.1% by weight of stearic acid amide as a slip agent. Regarding antistatic properties, the film was charged with an electric field of 10 KV, and then the electric field was reduced to 0 and the half-year of charge decay was measured. Regarding slipperiness, ASTMD1894−
The static friction coefficient was measured using a slip tester according to 73. Table 4 shows the results. It is clear that the technology of the present invention is also better in terms of antistatic properties and slipperiness than the prior art. Comparative Example 5 In place of P ₂ O ₅ in the glass composition of Example 1
A film was molded in the same manner except that PbO was used instead. This glass had a refractive index of 1.58 and an average particle size of 2 μm, but as shown in Table 3, its transparency was inferior to that of Example 1.

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Claims (1)

[Scope of Claims] 1. A thermoplastic synthetic resin film with improved blocking properties, which is obtained by adding 0.05% by weight or more and less than 1.0% by weight of fine glass powder to a transparent synthetic resin. 2. A thermoplastic synthetic resin film with improved blocking properties as claimed in claim 1, wherein the glass fine powder has a refractive index of 1.47 to 1.55 and the synthetic resin is polyolefin. 3 Fine glass powder contains 5 to 80 mol% of silicon dioxide, 1 to 50 mol% of alkali metal oxide, 0 to 40 mol% of alkaline earth metal oxide, and
A patent claim containing 0 to 50 mol% of one or more oxides selected from Al ₂ O ₃ , B ₂ O ₃ , P ₂ O ₅ , ZnO, TiO ₂ , or Bi ₂ O ₃ A thermoplastic synthetic resin film with improved blocking properties according to item 1.