JPH0516309A - Manufacture of mold-release film having antistatic performance - Google Patents

Abstract

PURPOSE:To provide the manufacture of a mold-release film having stable antistatic properties and excellent flatness and mold release characteristics with high productivity. CONSTITUTION:The manufacture of a mold-release film, which uses a polyester film, in which a silicon oxide film displaying antistatic properties by the action of silanol is formed on at least one surface of the film, forms a mold-release layer by coating the upper section of the silicon oxide film with the mixture of a silane isocyanate compound and polydimethylsiloxane occupying a rate smaller than the silane isocyanate compound and having a terminal hydroxyl group and curing mixture at a temperature of 60-130 deg.C and having antistatic performance, is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a release film having an antistatic property, and more particularly to a release film having a stable antistatic property, excellent flatness and releasability with high productivity. It relates to a method of manufacturing.

[0002]

2. Description of the Related Art In recent years, in accordance with a wide range of applications of pressure sensitive adhesives, adhesives, etc., the use of silicone-coated paper or film for protecting the pressure sensitive adhesive surface has been remarkably increased. In addition, for the molding of materials such as plastics and rubber, especially for molding vinyl chloride, epoxy, polyurethane, polyester resin, etc., silicone coated paper or film is applied to maintain moldability until curing reaction and cooling and curing. There is.
Further, paying attention to the lubricity of silicone, a large amount of silicone coating film having a low surface friction coefficient is used as a slip sheet of an audio cassette.

The silicones used in these silicone-coated papers and films are generally required to prevent surface sticking and to minimize backside migration of the silicone. Therefore, as a silicone, polydimethylsiloxane having an -OH group at the terminal and
Polydimethylsiloxane (Hydroxypolydimethylsiloxane) having H group by condensation reaction using an organotin catalyst to form a three-dimensional crosslinked structure, and polydimethylsiloxane and hydroxypolydimethylsiloxane having a vinyl group introduced at the terminal The type in which is subjected to an addition reaction using an organic catalyst is mainly used.

However, such a curing type silicone requires high temperature conditions when the coating film is cured, and a thickness of 50
If the film is less than μm, heat wrinkles are generated in the film,
The release film lacks the flatness.

Further, the silicone coating film formed in this manner has a drawback that it is easy to be charged without leakage of charges due to the main chain bond and the three-dimensional structure of the silicone. That is, the Si—O—Si bond of the main chain is basically an σ bond, although it is more ionic than the C—C bond, and delocalization of charges such as a conjugated double bond does not occur. Can not. Further, the two methyl groups bonded to Si face the outside of the main chain to form a hydrophobic field, and moisture in the air (H ₂ O)
And it becomes impossible to leak charges through the impurity ions.

Therefore, the film coated with the silicone thin film is naturally highly charged and causes various problems. For example, when the release film is used as a molded substrate of various resins, the amount of peeling charge is large and dust or the like adheres, and when repeatedly used, these cause defects on the surface of the molded resin due to adhered foreign matters. When it is used as an audio cassette slip sheet, friction with the tape reel may cause electrification, which may lead to running failure.

In Japanese Patent Publication No. 2-6625, a silicone resin is provided on at least one side of a plastic film with an undercoat layer made of a partial hydrolyzate of polysiloxane in which 80% or more of side chains and terminal groups are substituted with hydroxyl groups. A layer is formed, or a coating layer containing a partial hydrolyzate of the polysiloxane and a silicone resin is formed on at least one side of the plastic film to impart antistatic property, slipperiness and peeling property to the film. Is listed. However, the silicone resin requires high-temperature conditions when the coating film is cured, and is liable to have the drawback of poor flatness.

[0008]

DISCLOSURE OF THE INVENTION The present inventor has earnestly studied a method for producing a release film having stable antistatic property, excellent flatness and releasability without such drawbacks with high productivity. As a result, the present invention has been reached.

[0009]

That is, the present invention uses a polyester film in which a silicon oxide film exhibiting antistatic properties by the action of silanol is formed on at least one side of a film, and silane isocyanate is formed on the silicon oxide film. A mixture of the compound and a polydimethylsiloxane having a terminal hydroxyl group, which accounts for a smaller proportion than this, is applied, and
This is a method for producing a release film having antistatic properties, which comprises curing at a temperature of 130 ° C. to form a release layer.

The polyester film in the present invention is mainly a biaxially stretched film made of a polyester having an aromatic dicarboxylic acid as a main acid component and an alkylene glycol as a main diol component, and the alkylene glycol is, for example, an alicyclic group. It is also possible to substitute with other diols such as glycol, aliphatic glycol having an aromatic ring, and aromatic diol. Preferable examples of the aromatic dicarboxylic acid are terephthalic acid and 2,6-naphthalenedicarboxylic acid, and preferable examples of the alkylene glycol are ethylene glycol, tetramethylene glycol and hexamethylene glycol. Specific examples of the polyester include polyethylene terephthalate and polyethylene-2,6-naphthalate.

The polyester film is not restricted by the production method thereof. For example, polyester is melt-extruded to obtain an unstretched film, and then the unstretched film is sequentially stretched in the biaxial direction by a biaxial stretching method, followed by heat treatment. It can be manufactured by fixing. At that time, the transparency can be easily controlled by adjusting the particle size and amount of the lubricant such as clay, kaolin, silica, calcium carbonate and the like. Also, the thermal and mechanical properties can be controlled by adjusting the stretching and heat setting conditions. The polyester film has a thickness of 4 to 50 μm, and further 4 to 25 μm.
m, and particularly preferably 6 to 16 μm.

In the present invention, the silicon oxide film formed on at least one side of the polyester film is silanol.

[0013]

[Chemical 1] It is a silicon oxide film that exhibits antistatic properties by the action of, and forms a three-dimensional siloxane network, and can be said to be an antistatic layer. This silicon oxide film preferably has a surface specific resistance value of 10 ¹⁰ Ω / □ or less.

The silicon oxide film is formed by the hydrolysis and condensation reaction of a tetrafunctional silicon compound, and the water acting on this reaction may be, for example, the water adhering to the film surface or the water in the air.

Examples of the tetrafunctional silicon compound include (C
Examples thereof include chloropolysiloxanes such as l ₂ SiO) _n , and alkoxysilanes and alkoxypolysiloxanes that easily hydrolyze. This compound is preferably partially hydrolyzed by acting on water before coating, and particularly preferably a partial hydrolyzate in which 80% or more of side chains and terminal groups are substituted with hydroxyl groups.

The hydrolysis and condensation reaction of the tetrafunctional silicon compound can be carried out, for example, by alkoxysilane [Si (OR) ₄ , R =
Lower alkyl], under mild reaction conditions,

[0017]

[Chemical 2] Silanol is produced by the reaction of

[0018]

[Chemical 3] Is condensed by the reaction to form a glassy film of silicon oxide having a three-dimensional structure. This reaction is from room temperature to 120 ° C
With sufficient progress at the following temperature, the reaction by-product becomes a gas and has an advantage that there is no reaction residue.

When the partial hydrolyzate of a tetrafunctional silicon compound is applied to the surface of a film, as can be understood from the above, the film is cured under the influence of temperature and humidity to firmly adhere to the film and, at the same time, has excellent antistatic properties. To become sexual.

In the present invention, a mixture of a silane isocyanate compound and polydimethylsiloxane having a terminal hydroxyl group, which accounts for a smaller proportion than the above, is applied onto such a silicon oxide film, and the mixture is cured at a temperature of 60 to 130 ° C. and released. Form a mold layer.

This silane isocyanate compound has a molecule

[0022]

[Chemical 4] A compound having a bond, such as Si (NCO) ₄ ,
R _n Si (NCO) _4-n , (RO) _n Si (NCO)
_4-n , these precondensates and the like can be mentioned. Here, R is a hydrocarbon group such as methyl, ethyl, phenyl, vinyl, etc., and n is a number of 1, 2, or 3. Preferable examples of specific compounds include methylsilane triisocyanate, ethoxysilane triisocyanate, and silane tetraisocyanate. Further, the silane isocyanate compound is obtained by condensing the above compound with silicic acid anhydride or a polysiloxane compound to form two or more isocyanate groups (-NC) in the silane element (Si) in the molecule.
O) may be included in the compound. The silane isocyanate compound may be used alone or in combination of two or more. Of these, methylsilane triisocyanate is particularly preferred.

As the polydimethylsiloxane having terminal hydroxyl groups, those having two hydroxyl groups, so-called silicone diols are particularly preferable. The degree of polymerization of this product is 40 or less, more preferably 20 to 40. The degree of polymerization is preferably 10 or more.

The polydimethylsiloxane having a terminal hydroxyl group is preferably used in an amount of 5 to 30% by weight based on the total amount of the silane isocyanate compound. If the proportion of the polydimethylsiloxane having a terminal hydroxyl group is too large, the adhesion of the thin film will deteriorate, which is not preferable.

The coating liquid containing a mixture of a silane isocyanate compound and a polydimethylsiloxane having a terminal hydroxyl group can be coated by various coating methods such as spinner coating method, spray coating method, bar coating method, gravure coating method and reverse coating method. Can be done using. The silane isocyanate compound and the polydimethylsiloxane having a terminal hydroxyl group are excellent in low-temperature reactivity, for example, in a mild condition such as moisture in the air or moisture adhering to the polyester film surface without using a special catalyst. Since the reaction proceeds sufficiently, the drying temperature after coating can be lowered, so that there is an advantage that a releasable cured film can be formed without generating wrinkles, especially vertical wrinkles on the film. The drying temperature is usually 60 to 130 ° C, preferably 80 to 12
It is 0 ° C. If the temperature is too low, the curing time becomes long and the productivity is lowered, which is not preferable. On the other hand, if this temperature is too high, the film will wrinkle,
Not preferable. The above advantage becomes more remarkable as the thickness of the polyester film is smaller.

The silane isocyanate compound is hydrolyzed by reacting with moisture in the air in the drying step as described below,

[0027]

[Chemical 5] Furthermore, it is considered that the hydrolyzate reacts as described below to form a silicon oxide thin film.

[0028]

[Chemical 6] At that time, the reaction between the polydimethylsiloxane and the silane isocyanate compound also proceeds, and the polydimethylsiloxane chain can be bonded to the silicon oxide thin film. This polydimethylsiloxane chain is characteristically present on the surface of the thin film and imparts releasability to the thin film.

[0029]

EXAMPLES The present invention will be described in more detail with reference to the following examples. The various properties of the film were measured by the following methods.

1) Surface resistivity The surface resistivity is measured with a super insulation resistance meter (RM-214 manufactured by Yokogawa Electric) according to ASTM D-257.

2) A polyester adhesive tape (Knit-31B) was stuck on the releasable silicon oxide thin film layer, and after being pressure bonded with a 2 kg pressure roller for 20 minutes, it was cut into a tape width (1 inch),
Peel in 180 ° direction with an Instron type tensile tester, and display the resistance value (g / inch) at this time.

3) Coefficient of Friction According to ASTM D-1894, the coefficient of static friction and the coefficient of dynamic friction between the treated surface and the non-treated surface of the film are measured.

4) Love-off test The coated surface is rubbed several times with a fingertip, and the thin film is removed and the adhesion is checked.

5) Flatness Visually check for heat wrinkles on the film surface: ○: No occurrence ×: Many occurrences

[0035]

[Comparative Example 1] A trade name K manufactured by Shin-Etsu Chemical Co., Ltd. of a type in which a platinum catalyst is added to a mixed solution of polydimethylsiloxane and methylhydrogenpolysiloxane to cause an addition reaction and curing.
S-772 was dissolved in toluene to prepare a solution having a solid content concentration of 2%.

This coating solution was applied to a polyester film (thickness 6
μm) at a coating amount of 10 g / m ² (wet), and a curing reaction was performed at a drying temperature of 110 ° C. and a residence time of 1 minute to prepare a release film having a dry film thickness of 0.2 μm. The characteristics of this release film are shown in Table 1.

[0037]

[Comparative Example 2] The curing reaction was performed at a drying temperature of 140 ° C and a residence time of 1
The same procedure as in Comparative Example 1 was performed except that the procedure was performed in minutes. The properties of the obtained release film are shown in Table 1.

[0038]

Example 1 A polysiloxane hydrolyzate, Colcoat P, 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 applied to a polyester film (thickness 1
(6 μm) film was coated at a coating amount of 6 g / m ² (wet) and dried at a drying temperature of 100 ° C. and a residence time of 1 minute.

Further, on the film coated with Colcoat P, a solid content obtained by diluting IPA with a brand name Organix SIC-003 manufactured by Matsumoto Pharmaceutical Co., Ltd., which is a mixture of a silane triisocyanate compound and polydimethylsiloxane. A 3% solution was applied, and a curing reaction was performed at a drying temperature of 110 ° C. and a residence time of 1 minute. The properties of the obtained release film are shown in Table 1.

[0041]

Example 2 Example 1 was repeated except that a polyester film having a thickness of 6 μm was used. The properties of the obtained release film are shown in Table 1.

[0042]

[Table 1]

[0043]

According to the method of the present invention, for example, 10 ¹² Ω
It is possible to manufacture a release film having a surface specific resistance value of / □ or less, a stable antistatic property, and excellent flatness and releasability with high productivity. In particular, the present invention is effective for producing a wide thin film release film.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location B32B 27/36 7016-4F C08J 7/04 CFD 7258-4F C09J 7/02 JKV 6770-4J

Claims (4)

[Claims] 1. A polyester film in which a silicon oxide film exhibiting antistatic properties by the action of silanol is formed on at least one side of the film is used, and a silane isocyanate compound and a small proportion thereof are used on the silicon oxide film. A method for producing a release film having an antistatic property, which comprises applying a mixture with a polydimethylsiloxane having a terminal hydroxyl group and curing the mixture at a temperature of 60 to 130 ° C. to form a release layer. 2. The method for producing a release film having antistatic properties according to claim 1, wherein the proportion of the polydimethylsiloxane having a terminal hydroxyl group is 5 to 30% by weight based on the total amount of the silane isocyanate compound. 3. The method for producing a release film having antistatic properties according to claim 1, wherein the polydimethylsiloxane having a terminal hydroxyl group is a silicone diol having a polymerization degree of 40 or less. 4. A silicon oxide film is formed by applying a partial hydrolyzate of polysiloxane in which at least 80% of side chains and terminal groups are substituted with hydroxyl groups to at least one side of a polyester film and curing the film. Item 2. A method for producing a release film having an antistatic property according to item 1.