JPH05239229A - Production of thermoplastic resin film or sheet - Google Patents

Abstract

PURPOSE:To easily and advantageously produce a thermoplastic resin film or sheet. CONSTITUTION:This production method comprises casting a solution of a thermoplastic resin on a metal substrate and peeling the resulting film or sheet from the substrate when the residual solvent amount in the film or sheet has decreased to 20wt.% or smaller.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a thermoplastic resin film or sheet used in various fields such as a material for retardation film, a protective film for a polarizing film, an optical material for a liquid crystal cell panel and the like. Regarding

[0002]

A solution casting method is known as a method for obtaining a thermoplastic resin film or sheet having excellent thickness accuracy. In this method, a base material for casting the resin solution is required, and a metal base material such as a steel belt is generally used industrially. However, depending on the affinity between the resin solution used and the metal base material, the generated film adheres to the metal base material, which causes problems such as difficulty in peeling, stretching and tearing of the film. For,
I can't get enough. On the other hand, if a release-treated polyester film or the like is used as a substrate, such a problem does not occur, but this method is not an advantageous method when considering industrial production.

The inventors of the present invention have made extensive studies on the method for producing a thermoplastic resin film or sheet, and as a result, in the production of a thermoplastic resin film or sheet using a metal substrate by the solution casting method, the thermoplastic resin film or sheet is peeled from the metal substrate. The inventors have found that by defining the amount of residual solvent in the resin film or sheet at that time, the above problems can be solved, and a thermoplastic resin film or sheet can be obtained industrially advantageously, and the present invention has been accomplished.

[0004]

That is, the present invention provides a method for producing a thermoplastic resin film or sheet using a metal base material by a solution casting method, wherein the residual solvent amount in the resin film or sheet is 20% by weight or less. The present invention relates to a method for producing a thermoplastic resin film or sheet, which comprises peeling from a metal substrate when

The present invention will be described in detail below. The solution casting method in the present invention means, for example, casting a thermoplastic resin solution on a smooth base material, adjusting the thickness of the resin solution if necessary, and then removing the solvent of the resin solution to obtain a smooth base material. A method of peeling from a material.

Examples of the metal base material as the smooth base material used in the present invention include stainless steel, iron, aluminum, those metals and other metal surfaces having hard chrome plating, and the like. Depending on the purpose of the thermoplastic resin film or sheet to be produced, a mirror-finished surface of the metal substrate may be used.

Examples of the thermoplastic resin used in the present invention include polyethylene, polypropylene, nylon, ABS, polystyrene, polysulfone, polyimide, polymethylmethacrylate, polyvinyl alcohol,
Examples thereof include cellulose triacetate, cellulose diacetate, and polyether sulfone, which may be used alone or as a copolymer with another resin or another compound. It is also possible to use it as a resin composition containing 50% by weight or more of these resins. Preferred are polystyrene resins, polystyrene resins (copolymers of polystyrene with other resins or other compounds), polysulfone resins, or resin compositions containing 50% by weight or more of these resins.

The solvent used for forming the resin solution in the present invention is, for example, methylene chloride,
Halogenated aromatic or aliphatic hydrocarbons such as 1,2-dichloroethane and chlorobenzene, aromatic or aliphatic hydrocarbons such as hexane, heptane, benzene and toluene, esters such as ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, acetone Ketones, etc.
Aromatic or aliphatic alcohols such as cresol, phenol, isopropanol and butanol, formamides such as DMF, sulfoxides such as DMSO, N-methylpyrrolidone, water and the like can be mentioned. Further, in the present invention, a release agent such as a fluorine-based agent, a silicone-based agent, a stearic acid-based agent, or the like may be added to the resin solution. As a method for casting and adjusting the resin solution thickness, a usual method is used. For example, a T-die method and a doctor blade method can be mentioned. In addition, when the thickness of the resin solution is adjusted, the thickness is appropriately selected according to the application.

The casting and the removal of the solvent after adjusting the thickness of the resin solution are carried out by, for example, air drying, hot air drying, heating of the metal substrate, reduced pressure drying, a combination of these, or the like. In the removal of the solvent, it is necessary to separate the resin film or sheet from the metal base material by setting the residual solvent amount in the resin film or sheet to 20% by weight or less. Thereby, the peeling property between the resin film or sheet and the metal substrate is improved, and the resin film or sheet can be efficiently manufactured. The residual solvent amount is preferably 16% by weight or less. In particular, the method of the present invention is advantageously applied to the production of a film or sheet of polystyrene resin, polystyrene resin, polysulfone resin or the like. If peeling is carried out when the residual solvent amount exceeds 20% by weight, there arises inconveniences such as that the resin film or sheet cannot be peeled from the metal substrate and the resin film or sheet is broken. The residual solvent amount as referred to in the present invention is obtained by heating the resin film or sheet at a temperature equal to or higher than the boiling point of the solvent, and determining the weight loss before and after the heating, and is represented by the weight ratio of the residual solvent to the entire resin film or sheet. It was done. The solution casting method in the present invention can be applied to both a continuous method and a batch method. The thermoplastic resin film or sheet thus obtained may be used as it is depending on the purpose, or may be subjected to secondary processing such as stretching to obtain a retardation film or the like.

[0010]

EFFECTS OF THE INVENTION According to the present invention, a thermoplastic resin film or sheet can be easily produced by the solution casting method and industrially advantageous.

[0011]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited thereto. Example 1 Polystyrene (Sumibright E183 manufactured by Sumitomo Chemical Co., Ltd.) was dissolved in methylene chloride at 20% by weight to prepare a solution. This is 600μ on mirror-finished stainless steel
Peeling test is carried out after casting with a thickness of m to about 10 cm square and air-drying. The results are shown in Table 1.

[Table 1] In Table 1, ∘ indicates that the film could be uniformly peeled off, and x indicates that the film was partially pulled or broken.

Claims (3)

[Claims] 1. A method for producing a thermoplastic resin film or sheet using a metal base material by a solution casting method,
A method for producing a thermoplastic resin film or sheet, which comprises peeling from a metal substrate when the amount of residual solvent in the resin film or sheet becomes 20% by weight or less. 2. The method according to claim 1, wherein the thermoplastic resin is a resin or a resin composition containing 50% by weight or more of a polystyrene resin or a polystyrene resin. 3. The thermoplastic resin is 50 polysulfone resin.
The method according to claim 1, which is a resin or a resin composition containing at least wt%.