JP2807149B2 - Release film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film for resin molding, and more particularly, to a release film useful for forming a mat sheet made of a resin such as a vinyl chloride resin, a polyurethane or an acrylic resin.

[0002]

2. Description of the Related Art In recent years, in the molding of plastics, rubbers and the like, especially in the molding of sheets of vinyl chloride resin, epoxy resin, polyurethane, polyester resin, etc., usually, a solidification or curing reaction is carried out in order to maintain the moldability. Process
This method is performed by casting those resins on a film or paper coated with silicone or the like.

Among these resins, for example, in the case of vinyl chloride resin molding, in many cases, the sheet is a soft sheet or leather, and the surface thereof is matted with an uneven pattern resembling leather or fabric. There are many.

[0004] As a method of making the surface of the vinyl chloride sheet matte with irregularities, usually, embossing is performed in a step after the sheet is formed, for example, an embossing roll having a desired irregular pattern and a backup roll, and further, a temperature of about 150 ° C. There is a method of embossing using an embossing device having a heating device.

However, in such a method, in order to cope with various kinds of vinyl chloride sheets, capital investment and cost increase in an embossing device cannot be avoided. Further, it is technically time-consuming to form a mat by fine irregularities on the sheet surface.

[0006]

The inventor of the present invention has focused on the fact that the above problem can be solved if a concavo-convex pattern can be formed on the sheet surface at the time of sheet formation, and has developed a release film capable of forming a fine concavo-convex pattern on the sheet surface. As a result of intensive research for development, the present invention has been achieved.

[0007]

That is, the present invention is directed to a polysiloxane having a hydroxyl group at a side chain or at a terminal on at least one surface of a polyester film having a surface roughness Ra of 0.05 μm or more and a glossiness of 80% or less. A release film for resin molding, comprising a coating film using a partially hydrolyzed product.

The polyester in the present invention is a linear saturated polyester produced from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof, and specifically, polyethylene terephthalate, polypropylene terephthalate, Examples thereof include polybutylene terephthalate and polyethylene-2,6-naphthalate. Further, a copolymer in which a part of these is substituted with the third component, or a mixture with polyalkylene glycol or another resin may be used.

The polyester film of the present invention comprises:
Basically, it can be manufactured by a conventionally known method. For example, the polyester is dried and then melted,
Extruded from a die (for example, T-die, I-die, etc.) onto a cooling drum, quenched to obtain an unstretched film, and then stretched the unstretched film 2 to 4 times in the machine direction and 2 to 4 times in the transverse direction. 4
It can be manufactured by stretching twice and heat-setting at 180 to 240 ° C. The thickness of the film is not particularly limited, but is preferably 5 to 200 μm.

[0010] As a polyester film, the surface roughness R
It is not necessary to be transparent in terms of a and gloss, and in view of the slipperiness and processability of the film, lubricants such as inorganic fine particles such as calcium carbonate, kaolin, silica, and titanium oxide and / or catalyst residues may be used. A film containing precipitated fine particles or the like may be used, or a film containing other additives such as an antioxidant such as sodium dodecylsulfonate or a color tone adjuster may be used.

In order to impart a surface roughness (Ra) of 0.05 μm or more and a glossiness of 80% or less to a polyester film, a lubricant having a large particle size, for example, silicon oxide, titanium oxide, calcium carbonate, glass beads, silicone It is preferable to contain resin particles, crosslinked polystyrene particles, and the like. For example, it is preferable that silicon dioxide having an average particle size of 1 to 10 μm is added and contained in an amount of 0.1 to 5.0% by weight based on the weight of the polyester. The surface roughness Ra of the film is 0.1
It is preferably at least μm, more preferably at least 0.2 μm.

In the present invention, the water-soluble organic silane compound used for forming the undercoat layer has a structure having a hydrolyzable group usually bonded to a silicon atom and various organic functional groups. is there. This undercoat layer is desirably present in view of the long-term stability of the release layer.

Examples of such water-soluble organic silane compounds include γ-aminopropyltrimethoxysilane, γ
-Aminopropyltriethoxysilane, γ-aminopropylmethyldimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane , Γ
-Glycidoxymethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-β- (aminopropyl) -γ-aminopropylmethyl Dimethoxysilane, N-β- (aminoethyl)-
γ-aminopropyltriethoxysilane and the like. These are only examples of some of the water-soluble organosilane compounds that can be used in the present invention, and the present invention is not limited to these. The water-soluble organic silane compound is 1
Species or two or more can be used.

The hydrolyzable group in the water-soluble organic silane compound is considered to form a hydroxyl group by hydrolysis and to strengthen the bond with the hydroxyl group of the polysiloxane partial hydrolyzate applied on the undercoat layer. Organic functional groups having strong activity have strong affinity with polyester film and coating layer binder resin. For example, primary or secondary amino groups in the molecule are hydroxyl, carboxyl, epoxy and many other functional groups. , The bond between the film and the undercoat layer, or between the undercoat layer and the overcoat layer, is considered to be strong.

The water-soluble organic silane compound is usually used as an aqueous solution at a concentration of 0.1 to 5.0%, and the amount of the water-soluble organic silane compound applied to the surface of the polyester film is 0.02 to 0.
2 g / m ² (after drying) is preferred. The application of the water-soluble organic silane compound may be performed during the film forming process of the polyester film, or may be performed at a different place from the film forming process.
When it is performed during the film forming process, it can be applied to an unstretched film, a uniaxially stretched film (particularly a longitudinally stretched film), a biaxially stretched film, a film after biaxially stretched and heat-fixed, and the like. Of these, it is preferable to apply the film to a longitudinally stretched film before being subjected to transverse stretching. As a coating method, for example, spin coating, gravure roll coating, kiss coating, bar coating,
Various coating methods such as a reverse roll coating method can be used. The application is on one or both sides of the polyester film.

In the present invention, a polysiloxane partial hydrolyzate having a hydroxyl group at a side chain or at a terminal forming a release layer is a tetrafunctional silicon compound such as (Cl ₂ Si)
O) Chlorpolysiloxane such as n, or alkoxysilane which is apt to be hydrolyzed, or alkoxypolysiloxane such as ethyl silicate, etc., which is partially hydrolyzed by the action of water. A compound represented by the following formula in which 80% or more is substituted with a hydroxyl group (provided that the entire upper chain is substituted with a hydroxyl group for convenience).

[0017]

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Since this partial hydrolyzate is dissolved in alcohol, it is used as an alcohol solution, applied directly on the polyester film or on the undercoat layer, and dried by heating to form a film. In the heating and drying, the silanol is hydrolyzed by moisture in the atmosphere, and the generated silanol causes a condensation reaction to form a three-dimensionally bonded silicon oxide film.

These reactions are known and are schematically shown as follows.

[0020]

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This partial hydrolyzate can be obtained from the market, and examples thereof include Colcoat P, Colcoat R and Colcoat 920.

The release layer is directly formed on the polyester film,
Alternatively, in providing on the undercoat layer using a water-soluble organic silane compound, as a coating method, a conventionally known method such as a doctor blade method, a bar coating method, a gravure roll coating method, a reverse roll coating method, or the like is used. it can.

The release film of the present invention, as a release film for forming a matte sheet made of a resin such as a vinyl chloride resin or a polyurethane resin, exhibits stable release performance of coating film adhesion for a long period of time.

[0024]

The present invention will be further described below with reference to examples. The film characteristics in the examples were measured by the following methods.

(1) Film Surface Roughness Ra Using a stylus type surface roughness meter (Surfcoder 30C) manufactured by Kosaka Laboratory Co., Ltd., a chart was prepared under the conditions of a needle radius of 2 μm and a stylus pressure of 30 mg. Film surface roughness curve).
From the film surface roughness curve, a portion of the measured length L is extracted in the direction of the center line, and the center line of the extracted portion is indicated by X.
Axis, the direction of the vertical magnification is the Y axis, and the roughness curve is Y = f
When represented by (x), R given by the following equation (Equation 1)
a (μm) is defined as the film surface roughness.

[0026]

(Equation 1)

(2) Film glossiness Digital gloss meter GM-3D (Murakami Color Research Laboratory Co., Ltd.)
) At a measurement angle (specular reflection angle) of 60 °.

[0028]

Example 1 Molten polyethylene terephthalate containing 1.5% silicon dioxide having an average particle size of about 6 μm based on the weight of polyester was extruded from a die and adhered to a rotating cooling drum maintained at about 40 ° C. while applying static electricity. The film is quenched to obtain an unstretched film, and then the unstretched film is stretched 2.8 times in the machine direction and then 3.0 times in the transverse direction.
Heat fixing was performed at 20 ° C. to obtain a biaxially stretched polyethylene terephthalate film having a thickness of 75 μm. This film had a surface roughness Ra of 0.38 μm and a glossiness of 40%.

A partial hydrolyzate of tetraalkoxysilane, Colcoat P (trade name, manufactured by Colcoat Co., Ltd.) was diluted with isopropyl alcohol (IPA) to prepare a solution having a solid content of 1.5%.

This coating solution was coated on the biaxially stretched polyethylene terephthalate film at a coating amount of 6 g / m ² (wet) and dried at a drying temperature of 120 ° C. for a drying time of 1 minute.

A vinyl chloride resin was cast on the release film thus obtained, and then released, whereby a sheet-like vinyl chloride resin was obtained. Also,
The surface of the released resin sheet was a matte surface.

[0032]

Comparative Example 1 Molten polyethylene terephthalate containing 0.2% of silicon dioxide having an average particle diameter of about 0.6 μm based on the weight of polyester was extruded from a die, and static electricity was applied on a rotary cooling drum maintained at about 40 ° C. The unstretched film is adhered and quenched to obtain an unstretched film, and then the unstretched film is stretched 3.6 times in the machine direction and 3.9 times in the transverse direction, and then heat-set at 220 ° C. to a thickness of 75 μm. The biaxially stretched polyethylene terephthalate film was obtained. This film had a surface roughness Ra of 0.02 μm and a glossiness of 92%.

A partial hydrolyzate of tetraalkoxysilane, Colcoat P (trade name, manufactured by Colcoat Co., Ltd.) was diluted with isopropyl alcohol (IPA) to prepare a solution having a solid content of 1.5%.

This coating solution was coated on the biaxially stretched polyethylene terephthalate film at a coating amount of 6 g / m ² (wet) and dried at a drying temperature of 120 ° C. for a drying time of 1 minute.

By casting a vinyl chloride resin on the release film thus obtained and then releasing the same, a sheet-like vinyl chloride resin was obtained. The surface was shiny.

[0036]

According to the present invention, it is possible to provide a release film having excellent release properties from a resin such as a vinyl chloride resin and forming a mat on the surface of the released resin sheet. it can.

Claims (2)

(57) [Claims] 1. A polyester film having a surface roughness Ra of at least 0.05 μm and a gloss of at most 80% is coated on at least one side with a partially hydrolyzed polysiloxane having a hydroxyl group at a side chain or at a terminal. A release film for resin molding characterized by being provided. 2. A polyester film having a surface roughness Ra of not less than 0.05 μm and a gloss of not more than 80% is provided with a hydroxyl group on a side chain or a terminal thereof through an undercoat layer using a water-soluble organic silane compound. A release film for resin molding, comprising a coating film using a partially hydrolyzed polysiloxane.