JPH02219832A - Polyester film - Google Patents

Abstract

PURPOSE:To obtain a polyester film improved in weathering resistance, transparency and flexibility by reacting a specified dicarboxylic acid component with a glycol component based on 1,4-cyclohexanedimethanol and forming the product into a film. CONSTITUTION:A soft polyester (A) is obtained by reacting a dicarboxylic acid component based on 5-100mol% aliphatic dicarboxylic acid (e.g. 1,4- cyclohexanedicarboxylic acid) and 5-100mol% long-chain dicarboxylic acid having at least 18 methylene groups (e.g. dimer acid) with a glycol component based on 1,4-cyclohexanedimethanol. Component A is optionally mixed with 0.5-20wt.%, based on component A, weathering agent (B) and is formed into a film, which is optionally subjected to biaxial orientation and heat setting to obtain a polyester film of a tear propagation resistance >=5g/mum and a haze <5% in a 100mum thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a soft polyester film that has excellent weather resistance, transparency, and flexibility.

[Conventional technology]

Traditionally, flexible materials such as polyvinyl chloride and polyester ether have been mainly used as base films for agricultural tunnels and greenhouses, as well as for insulation tapes, and polyvinyl chloride is included in these materials. There is a drawback that additives such as plasticizers bleed out, resulting in deterioration of transparency, adhesiveness, flexibility, etc. Furthermore, due to poor weather resistance, they are not stable enough, and when used for agricultural greenhouses or tunnels that are strongly exposed to sunlight, the film deteriorates and the material tears, resulting in a significant reduction in heat retention. There is a drawback. In addition, since polyester ether contains an ether component, it has very poor weather resistance, and has the drawback that it hardens over time, resulting in even worse transparency. In other words, there has been no soft polyester film that has both weather resistance and transparency.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to provide a film that is excellent in weather resistance, transparency, and flexibility.

[Means for Solving the Problems] As a result of intensive research, the present inventors have found that the above problems can be solved by using a laminated film made of a specific polyester film, and have completed the present invention.

That is, 5 the present invention uses 5 mol% to 100 mol% of an alicyclic dicarboxylic acid and 5 mol% to 100 mol% of one or more types of long-chain dicarboxylic acids having 18 or more methylene groups as main dicarboxylic acid components, 1. A polyester film made of polyester containing 4-cyclohexalinemethanol as a main glycol component and having a tear propagation resistance of 5 g/μI or more is provided.

Furthermore, the present invention provides a laminated polyester film in which a layer A of a polyester film having a glass transition temperature Tg of 40° C. or higher and a layer B of the polyester film of the present invention are laminated in the order of A/B/A. I will provide a.

[Effect of the Invention 1] The present invention provided a polyester film with excellent weather resistance, transparency, and flexibility. Therefore.

The film of the present invention exhibits particularly excellent effects in agricultural applications such as tunnels and greenhouses, various molded containers that require weather resistance and transparency, and insulating tapes. Furthermore, due to its properties, it can also be used as pinhole-resistant packaging material, receiving paper for video printers, etc.

[Detailed Description of the Invention] The polyester in the present invention contains 5 mol % to 100 mol % of an alicyclic dicarboxylic acid such as 1,4-cyclohexanedicarboxylic acid.
mol% and one or more types of long chain dicarboxylic acids having 18 or more methylene groups such as dimer acid and eicoic acid, 5 mol% to 10
A polyester (hereinafter sometimes referred to as soft polyester) containing 0 mol% as the main component of dicarboxylic acid and 1,4-cyclohexalinemethanol as the main component of glycol. 0 does not adversely affect the effects of the present invention. If so, less than 550 mol% of other organic polymers, such as polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycyclohexylene dimethylene terephthalate, polyamides such as nylon 6, nylon 66, and nylon 11, It may also contain polyolefins such as polyethylene and polypropylene.

The soft polyester in the present invention can be produced by a known method such as a direct esterification method or a transesterification method. A weathering agent may be added as an additive during polymerization. When producing a soft polyester film, which will be described in detail below, it may be triblended with soft polyester and then extruded.

The amount of weathering agent that can be added when melting in an extruder is usually 0.5 to the weight of the soft polyester.
% to 20% by weight, preferably 1% to 1% by weight
It is about 0% by weight. If it is less than 0.5% by weight, the effect of suppressing ultraviolet deterioration cannot be expected.Ultraviolet absorbers such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, and 2-hydroxy-4
-n-octoxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2.2°, 4,4°
-Tetrahydroxybenzophenone, 2.2°-dihydroxy-4,4′-dimethoxybenzophenone and other benzophenones, 2(2′-hydroxy-5-methylphenyl)benzotriazole, 2(2′-hydroxy-3
゛, 5°-di-t-butylphenyl)benzotriazole, 2(2゛-hydroxy-3゛-di-t-butyl-5
Examples include benzotriazole-based UV absorbers such as -methylphenyl)benzotriazole, and salicylic acid-based UV absorbers such as phenyl salicylate and methyl salicylate. Other additives may include antioxidants and pigments such as mono-bis-trisphenol, aromatic amines, mercaptans, mono-di-polysulfides, dithiocarbamates, etc. The amount of these added is usually 0.01 weight. % to 5% by weight.

The polyester film of the present invention has a tear propagation resistance of 5 g/uw+ or more, preferably 15 g/μ1 or more. If the tear propagation resistance is less than 5g/μ-, tearing tends to occur during use, which often poses a practical problem.In order to keep the tear propagation resistance within the above range, the structure of the polyester resin used must be specified. This can be achieved by In addition, it is preferable that the natural recovery rate after being stretched by 50% at 23°C is 80% or more, and the soft polyester film of the present invention has a haze value of 5% or less when measured in the form of a sheet with a thickness of 100 gg+. Films with high softness such as polyester ethers other than those of the present invention not only have poor weather resistance, but even if a weathering agent is added to the soft layer, the weather resistance does not improve significantly. However, there is a further drawback that the resulting film becomes cloudy over time.

The soft polyester film in the present invention is preferably two-wheel oriented from the viewpoints of transparency, weather resistance, heat resistance, and durability.

The thickness of the soft polyester film of the present invention is not particularly limited, but is usually about 10 μm to 1 μm, preferably about 25 μm to 500 μm.

The laminated soft polyester film of the present invention further includes a layer A of a film made of polyester having a glass transition temperature Tg of 40°C or higher and a layer B of the soft polyester film of the present invention, which are laminated in the order of A/B/A. Constructed of laminated polyester film.

Layer A of the polyester film in the present invention is a film made of polyester such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polycyclohexylene dimethylene terephthalate. These can be used as a single polymer or as a copolymer. Furthermore, other components may be copolymerized or other polymers may be blended to the extent that the effects of the present invention are not impaired, and of course, weathering agents, slip agents, etc. may be added as additives. good.

In the present invention, the glass transition point Tg of the polyester of layer A
is 40°C or higher, preferably 65°C or higher. If the glass transition point is lower than 40° C., it is undesirable from the viewpoint that not only the transparency deteriorates over time, but also the slipperiness of the film is poor, resulting in wrinkles and defects such as loss of flatness. The glass transition point can be adjusted by controlling the structure of the polymer and the degree of molecular orientation.

In the present invention, the melting point of the polyester film of layer A is 2
It is preferably 25°C or higher, particularly 250°C or higher. If the melting point is lower than 225°C, not only will the weather resistance be poor, but the thermal dimensional stability will also be poor. The melting point of the polymer can be adjusted by controlling the constituent components of the polymer and their proportions.

In the present invention, the polyester film of layer A may be unstretched or -axially stretched, but biaxially stretched is particularly preferred from the viewpoint of heat resistance and durability. 0.5μl to 20μ−, preferably lμ
-~10μ- approximately.

It may be preferable that an anti-fog coating layer is formed on the surface of the soft polyester film or laminated soft polyester film of the present invention. Anti-fog coating layers are well known in the art and can be formed, for example, by applying an aqueous solution of a wood-philic polymer such as polyvinyl alcohol, polyacrylamide, polyacrylic acid, gelatin, collagen, cellulose, etc. and drying. can.

The laminated soft polyester film in the present invention can be obtained by melt extruding, cooling and stretching each film in accordance with a conventional method, and then bonding them together by heat treatment or using an adhesive, or by melting each polyvarnish-chill chip separately, Publicly known 3
Co-extruded using a laminated die, tightly adhered on a cooling drum,
After molding, there is a method of stretching and heat setting if necessary. In the former method, the melting temperature is not particularly limited, but for soft polyester it is 150°C to 280°C;
More preferably, the temperature is 180°C to 240°C, and for the polyester film of layer A, the temperature is 180°C to 31°C.
0°C, more preferably 200°C to 290"C, casting is preferably carried out by electrostatic application method,
The temperature of the casting drum is not particularly limited, but A
For layered polyester films, the temperature is usually 5-60°C,
Preferably 15°C, usually 5°C to 40°C for soft polyester films, preferably 10°C to 3°C.
The temperature is 5°C. Further, stretching after cooling may or may not be carried out, but when stretching is carried out, the polyester of layer A is usually stretched at a temperature of 50°C to 160°C in both the longitudinal and transverse directions.
1. Usually at a temperature of 80°C to 110°C, preferably 2.
At a stretching ratio of 5 to 6.0 times, for soft polyester films, the stretching ratio is usually 25 to 140 °C, preferably 40 to 100 °C, and 2.5 to 8.
It is carried out at a stretching ratio of 100%. The Fl temperature when heat-setting the film after stretching is usually 160°C to 250°C, preferably 180°C for the A-layer polyester film.
°C to 235 °C, usually 3 seconds to 20 seconds, preferably 6 seconds to 12 seconds, and for soft polyester films usually 80 °C to 200 °C, preferably IO
Q'c to 180°C, usually 3 seconds to 15 seconds, preferably 6 seconds to 10 seconds. Further, as the adhesive, known adhesives such as urethane-based, polyester-based, and acrylic-based adhesives can be used. The melting temperature when coextruding three layers is not particularly limited, but is preferably 150°C to 300°C, and the casting temperature is usually 10°C.
45° C. to 45° C., preferably 15° C. to 40° C., stretching is usually 40° C. to 140° C., preferably 70° C. to 110° C., in both machine and transverse directions, usually 3 to 6 times, preferably 4 to 5 times. It is carried out at a stretching ratio of 100%.

The heat setting after stretching is performed at a temperature between the melting temperatures of the above films, that is, 160°C to 250°C, for 3 seconds to 200°C.
It is preferable to do this for 0 seconds.

Next, the film characteristics specified in the present invention and the method for evaluating the effects of the present invention adopted in the following examples will be explained.

[1] Glass transition temperature sample 5B was set in a scanning calorimeter (DSC), and h
The endothermic peak that appears after the temperature is raised at 20° C./min under an air flow or the point of inflection from the baseline is adopted.

(2) Melting point Ts Sample 5B is set in a scanning calorimeter (DSC), and the endothermic peak temperature accompanying crystal melting that appears when the temperature is raised at a rate of 20° C./min under a nitrogen stream is defined as the melting point.

(3) Tear propagation resistance Measured according to STM D 1922.

(4) Transparency JIS film haze after heating at 75°C for 48 hours
Measured according to -X-6714.

Color 11J Good: When the film haze is 5% or less. Poor: When the film haze is over 10%.

1IJ Good: Poor when the elongation at break is 1/2 or more of the original value; Poor when the elongation at break is less than or equal to the original value of 115 [Example] The present invention will be explained in more detail below based on an example.

However, the present invention is not limited to the following examples.

! Fifty five yuan. An acid component consisting of 80 mol% of 4-cyclohexanedicarboxylic acid and 6120 mol% of Timer, and a glycol component consisting of 100 mol% of 1,4-cyclohexaline methanol were mixed with 0.05% by weight of titanium oxide based on the acid component as a catalyst. Transesterification was carried out by heating with stirring in an autoclave, and then Tinuvin P, 32B (manufactured by Geigy) was used as an ultraviolet absorber for 50 minutes.
% by weight was added and polycondensed to obtain a soft polyester. The obtained soft polyester and polyethylene terephthalate chips with an intrinsic viscosity of 0.65 were each melted at 280°C, and then extruded using a 3-layer coextrusion T-die die,
The three layers of film were brought into close contact with each other while applying electrostatic charge on a casting drum kept at 0.degree. C. to obtain an unstretched film. This unstretched film was brought into contact with a metal roll adjusted to 90° C. and preheated, and then stretched 4 times between rolls with a difference in circumferential speed while being irradiated with an infrared heater. Subsequently, the longitudinally stretched film was laterally stretched 3.7 times at 115° C. using a tenter. While holding both ends of the obtained biaxially oriented film with clips,
The film was heat-set at 30° C. and wound into a film having a thickness of 100 μm.

When the transparency and weather resistance of the obtained film were evaluated, the haze was 2%, the tear propagation resistance was 15 g/μ, and the weather resistance was good for more than 1000 hours. Moreover, the glass transition point of the polyester film of layer A of the laminated film was 80°C, and the melting point was 260°C.

Ratio W Instead of the polyester used in Example 1.

A two-wheel stretched film with a thickness of 100 μm was obtained in exactly the same manner as in Example 1 except that a polyethylene terephthalate/polytetramethylene glycol (50,150 mol %) block copolymer was used.

The resulting film had a haze of 45%, a tear propagation resistance of 4 g/μ■, and a weather resistance of 150 hours. Thus, it can be seen that only a sheet with no weather resistance can be obtained.

Claims (5)

[Claims] (1) Alicyclic dicarboxylic acid 5 mol% to 100 mol%
and 5 mol% to 100 mol% of one or more long-chain dicarboxylic acids having 18 or more methylene groups as the main dicarboxylic acid component and 1,4-cyclohexalinemethanol as the main glycol component,
A polyester film having tear propagation resistance of 5 g/μm or more. (2) The polyester film according to claim 1, wherein an anti-fog coating layer is formed on the surface. (3) The polyester film according to claim 1 or 2, characterized in that the polyester contains a weathering agent. (4) The polyester film according to any one of claims 1 to 3, which has a haze of less than 5% at a thickness of 180 μm. (5) A laminated polyester film, in which layer A of a polyester film having a glass transition temperature Tg of 40° C. or higher and layer B of the polyester film according to claim 1 are laminated in the order of A/B/A.