JPH03234738A - Opaque polyester film with roughened surface - Google Patents

Abstract

PURPOSE:To prepare an opaque polyester film having a uniformly roughened surface and contg. no coarse particles by mixing a polyester with a specified amt. of silicon dioxide or an aluminosilicate having specified physical properties. CONSTITUTION:A polyester, pref. a pelletized polyester, is mixed with 0.5-30wt.% silicon dioxide or aluminosilicate having a mean particle diameter of 0.1-10mum and an apparent density of 0.5g/cm<3> or higher. The pelletized polyester is pref. because it facilitates the dispersion of the silicon dioxide or aluminosilicate in the mixing machine even when the polyester is highly loaded with the silicon dioxide or aluminosilicate.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a roughened opaque polyester film that has a roughened film surface and is used for tracing papers, labels, release materials, gold and silver threads, etc. be.

[Conventional technology]

Conventionally, roughened polyester films include those whose surface has been roughened by physical treatment such as sandblasting or embossing, or those whose surface has been roughened by chemical treatment with acid or alkali. ing. In addition, films coated with inorganic or organic fine particles (Japanese Unexamined Patent Publication No. 61-2556), polyester containing inorganic fine particles to roughen the surface (Japanese Unexamined Patent Publication No. 56-88426), etc. It has been known.

However, in the above-mentioned conventional techniques, physical treatment and chemical treatment have drawbacks such as uneven roughening of the film surface, long processing time, and low productivity. Furthermore, the coating treatment has the disadvantage that the adhesion between the coating layer and the support is weak, and the coating layer may peel off during writing or the like.

In addition, in the method of incorporating In-free particles into polyester, it is necessary to add a large amount of In-free particles to roughen the film surface, which tends to cause particle aggregation, and the film surface cannot be uniformly roughened. It was difficult to do.

[Problem to be solved by the invention]

The present invention was made in view of the above circumstances, and its purpose is to eliminate the presence of coarse particles without the presence of coarse particles.
The object of the present invention is to provide a uniformly roughened opaque polyester film.

[Means to solve the problem]

is 0.5 aluminum silicate to polyester.
This is achieved by a roughened opaque polyester film characterized by containing ~30% by weight.

The present invention will be explained in detail below.

The polyester in the present invention is a condensation polymerization of dicarboxylic acid components such as terephthalic acid, isophthalic acid, phthalic acid, adipic acid, and sebacic acid and diol components such as ethylene glycol, diethylene glycol, polyethylene glycol, neohentyl glycol, and butanediol. It refers to a polymer compound obtained by the above-mentioned method, and also includes a copolymer.

Next, in the present invention, the inorganic fine particles contained in the polyester are silicon dioxide or aluminum silicate salts and satisfy the following conditions. That is, first, the average particle size is 0.1 to 10.0 μm,
Preferably it is 0.5-6.0 pm. If the average particle size is outside the above range, the filtration pressure will increase in the polymer filtration process during the formation of a good roughened film, leading to a decrease in productivity.Furthermore, it is preferable that the particle size is as uniform as possible.

Next, it is necessary that the apparent specific gravity is 0-5 g/cm3 or more. If the apparent specific gravity is less than 0.5 g/cm'', poor dispersion of silicon dioxide or aluminum silicate in the polyester will occur, making it impossible to obtain a uniformly roughened opaque film. , coarse particles due to poor dispersion cause film breakage in the film stretching process.

Furthermore, the shape of silicon dioxide or aluminum silicate is preferably cubic or spherical from the viewpoint of improving dispersibility.

Even if the silicon dioxide or aluminum silicate salt mentioned above is a synthetic product, it must be a natural mineral and have a content of 75% by weight or more of the total aluminum silicate salt, and an aluminum oxide content of 45% by weight. It is preferable that it is below. Note that the silicon dioxide or aluminum silicate salt may contain impurities such as sodium oxide, calcium oxide, iron oxide, and the like.

Further, the whiteness of silicon dioxide or aluminum silicate is preferably 80% or more, more preferably 90%.
That's all. When the whiteness is less than 80%, the resulting polyester film is unlikely to have satisfactory opacity.

In the present invention, the content of silicon dioxide or aluminum silicate is 0.5 to 30% based on the polyester.
% by weight, preferably from 1.0 to 20% by weight. If the content is less than 0.5% by weight, a polyester film with a sufficiently roughened surface cannot be obtained. On the contrary, the content is 3
If it exceeds 0% by weight, poor dispersion of silicon dioxide or aluminum silicate salt or film tearing due to a decrease in film strength will occur during the film stretching process.

Next, examples of the method for manufacturing the polyester film of the present invention include the following method. That is, first,
An example of a method for mixing polyester with silicon dioxide or aluminum silicate is a method of adding silicon dioxide or aluminum silicate during polyester polymerization.

There are methods such as mixing polyester pellets in a mixer. In particular, the method of mixing silicon dioxide or aluminum silicate into a polyester pellet can prevent silicon dioxide or aluminum silicate from agglomerating during the reaction to form coarse particles, and without rapidly thickening the reaction system. Even if the salt is at a high concentration, it is suitable because it is easy to disperse.

Next, a mixture of polyester and silicon dioxide or aluminum silicate is melt-extruded and then stretched on two wheels.For example, the mixture is supplied to an extruder heated to 260 to 300°C and melt-extruded from a T-shaped die. Next, it is cooled and solidified in a cooling drum at 20 to 60°C to form an unstretched sheet, and then stretched at a stretching temperature of 80 to 130°C in both the longitudinal and lateral directions or simultaneously in the longitudinal and lateral directions.Finally, in order to improve the dimensional stability of the film, By heat setting at ~230°C, the roughened opaque polyester film of the present invention is obtained.

Furthermore, the polyester film may contain various commonly used additives such as antioxidants, antistatic agents, pigments, and ultraviolet absorbers.

The roughened opaque polyester film thus obtained can be suitably used for applications such as tracing paper, labels, release materials, gold and silver threads, and the like.

〔Effect of the invention〕

As described above, the polyester film of the present invention has an average particle size of 0.1 to 10 μm and an apparent specific gravity of 0.5 g/cm3.
By using the above silicon dioxide or argonium silicate salt, inorganic fine particles are uniformly dispersed in the film, and a high-quality roughened opaque polyester with a uniformly roughened surface is produced without the presence of coarse particles. It's a film.

Further, by changing the average particle size and the amount of silicon dioxide or aluminum silicate added, a desired roughened opaque polyester film can be easily obtained.

The roughened opaque polyester film of the present invention has excellent writability, erasability, printability, I11 type property, metal deposition property, etc., and is suitable for tracing paper, labels, and H-shaped materials.

It is preferably used for applications such as gold and silver thread.

The present invention will be specifically described below with reference to Examples.

The main physical property measurement and evaluation methods used in the Examples are as follows.

+11 Average particle size The average particle size of silicon dioxide or aluminum silicate salt is measured using a particle size distribution measuring device, Coulter Co., Ltd.

The cumulative weight particle size distribution was measured using a Coulter Multisizer, and the 50% equivalent particle size was determined as the average particle size.

(2) Apparent specific gravity The apparent specific gravity of silicon dioxide or aluminum silicate was measured by the iron cylinder method in accordance with JIS K-6220-6-8.

(3) Oil absorption The oil absorption of silicon dioxide or aluminum silicate was measured using linseed oil in accordance with JIS K-5101-19.

(4) Dispersibility The two-wheel stretched film was visually measured and measured according to the following criteria.

O: No aggregation of silicon dioxide or aluminum silicate, good dispersibility △:: Slight aggregation of silicon oxide or aluminum silicate, slightly poor dispersibility ×:: Aggregation of silicon oxide or aluminum silicate Many, poor dispersibility (5) Film with roughened surface Writing was performed on the two-wheeled stretched film with an HB pencil and erased with an eraser, and measurement was performed according to the following criteria.

○: Good writability and erasability Δ: Slightly poor writability and erasability ×: Poor both writability and erasability [Examples 1 to 5. Comparative Examples 1 to 5] Sufficiently dried polyethylene terephthalate and silicon dioxide or aluminum silicate were melted and mixed in a kneader heated to 280°C, extruded into a bare shape, and then turned into a zero-order product. The sufficiently dried pellets were fed into an extruder heated to 280°C, melt-extruded through a T-shaped die, cooled and solidified in a cooling drum at 50°C to form an unstretched sheet, and then longitudinally stretched and stretched at a stretching temperature of 90°C. It was laterally stretched at a temperature of 95°C and finally heat-set at 210°C to obtain a film with a thickness of 12 μm.

Physical properties of silicon dioxide or aluminum silicate mixed with PET (apparent specific gravity, average particle size, oil absorption, shape),
The amount added and the dispersibility of silicon dioxide or aluminum silicate in the obtained film From the results shown in Table 1, the polyester film of the example was uniformly roughened and the roughened state was good. On the other hand, the polyester film of the comparative example was not uniformly roughened.

Claims (1)

[Claims] Average particle size 0.1-10.0μm, apparent specific gravity 0.5g/c
A roughened opaque polyester film containing 0.5 to 30% by weight of silicon dioxide or aluminum silicate having a particle diameter of m^3 or more based on the weight of the polyester.