JPS61235148A - Transparent polyester film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a transparent polyester film having an anti-whitening agent layer and excellent in maintaining transparency. This is preferably applied to, for example, a liquid crystal display device.

Conventional technology and problems Polyester film has good transparency.

Based on its mechanical properties, it is widely used in optics-related fields as transparent conductive films and substrates for liquid crystal differential cells.

However, on the other hand, there is a problem in that there are limits to its use due to its ability to maintain transparency. In other words, 1. For example, in certain cases during high-temperature heat treatment (annealing) to make the film low-yield A8:, low molecular weight molecules such as oligomers and lubricants in the film precipitate on the surface, and this causes There was a serious problem that the film became white and its transparency decreased. This whitening phenomenon often poses a problem particularly in optical-related fields.

For this reason, polyester films have traditionally been known for their transparency, heat resistance, mechanical properties, etc. 17c, i? It has been desired to provide a polyester film that substantially retains the advantages of whitening and does not have a decrease in transparency due to the whitening phenomenon mentioned above.
Nothing satisfactory has been proposed yet.

Means for Solving the Problems In view of the above circumstances, the inventors of the present invention have conducted intensive research to develop a polyester film that overcomes the above-mentioned problems. It's arrived.

That is, the present invention provides a transparent polyester film provided with an anti-whitening agent layer.

Examples of the polyester film used in the present invention include polyethylene terephthalate.

Examples include single-component, copolymerized, crosslinked, and mixed transparent films containing saturated polyester such as polybutylene terephthalate, as well as uniaxially stretched transparent films. The thickness is generally 20 to 500 μm, but is not limited thereto. Note that the film may contain various additives such as a lubricant.

On the other hand, as the anti-whitening agent, a silane coupling agent is preferably used. Specific representative examples include Teha, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyVethoxy)silane, r-glycidoxyglobyltrimethoxysilane, r-methacryloxypropyltrimethoxysilane, N-β (Aminoech/L'
) γ-aminopropyμmethyldimethoxysilane, γ-chloropropy-trimethoxysilane, γ-mercaptopropy-trimethoxysilane, r-aminopropyltriethoxysilane, and the like.

The transparent polyester film of the present invention preferably has 5 layers of an anti-whitening agent on both sides of the polyester film.
The thickness is 8 μm to 8 μm, preferably 1 μm to 100 μm. If the layer thickness is less than 5 μm, whitening in a high temperature atmosphere cannot be sufficiently prevented, and if it exceeds 8 μm, the resulting film will have poor flexibility, which is not preferred. For forming the layer, an appropriate N film forming method can be applied depending on the intended use of the film, such as a spinner coat method, a bar code method, a dipping coat method, or a method using a coating machine. There is no particular limitation on the formation method.

Effects of the Invention According to the present invention, since the anti-whitening agent layer is provided on the polyester film, even when the polyester film is exposed to a high temperature atmosphere, low molecular weight molecules, lubricants, etc. in the polyester film do not precipitate on the film surface. As a result of being suppressed or prevented, whitening of the film is effectively prevented and its transparency is maintained well.

Example 5 Example 1 Vinyl triethoxysilane (manufactured by Shin-Etsu Silicon Co., Ltd., KBE
1008') in isopropyl-fi/Fluco-fi/ to prepare a 5% by weight solution, which was applied to a 100 μm thick polyenalene terephthalate film (manufactured by Diafoil Co., Ltd., type 0 PET) using a spinner coating method. After coating on both sides, heat treated at 150°C for 3 minutes to give a 0.1μ
A layer of vinyltriethoxysilane with a thickness of m was formed.

Example 2 Using r-mercagutoprobyltrimethquine silane (manufactured by Shin-Etsu Silicon Co., Ltd., KBM801), the thickness of this layer was reduced to 0.
．． A polyester film was obtained according to Example 1 except that the thickness was 5 μm.

Example 8 Using γ-aminopropytriethoxysilane (manufactured by Shin-Etsu Silicon Co., Ltd., KBM903), the thickness of this layer was 800 mm.
In addition to the polyester film #i, a polyester film was obtained according to Example IVc.

Comparative Example 48 The same polyethylene terephthalate film as in Example 1 was used.

The films of the evaluation test examples and comparative examples were placed in a dryer at 150°C, taken out after a predetermined period of time, and their haze values were examined. The results are shown in the table.

From the table, it can be seen that the polyester film of the present invention provided with an anti-whitening agent layer has excellent transparency maintenance even under high temperature atmosphere.

Claims (1)

[Claims] 1. A transparent polyester film characterized by having an anti-whitening agent layer added to the polyester film. 2. The film according to claim 1, wherein the polyester film is a uniaxially stretched film. 3. The film according to claim 1, wherein the anti-whitening agent layer comprises a silane coupling agent.