JP3459722B2 - 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, and more specifically, a resin useful as a protective film for a pressure-sensitive adhesive coating applied by using an aqueous paint, or a resin formed by using an aqueous solution or an aqueous slurry. The present invention relates to a release film useful as a carrier film for molding sheets, resin coatings, ceramic sheets and the like.

[0002]

2. Description of the Related Art Release films are widely used as protective films for various adhesive coatings. Such a pressure-sensitive adhesive film is usually applied by a method of applying a coating liquid containing a pressure-sensitive adhesive and a solvent on the surface of the base film and then heating to remove the solvent. The release film is laminated on the surface of the pressure-sensitive adhesive film and used as a protective film.

The release film is also used as a carrier film when molding a resin sheet, a resin film, a ceramic sheet or the like. For example, the resin sheet is
After coating (casting) a resin solution consisting of a resin solvent such as vinyl chloride resin on a release film (carrier film),
The solvent is removed by heating to form a vinyl chloride sheet or the like for a marking sheet, which is peeled off from the carrier film and used for various purposes. The resin film is formed by applying a coating liquid containing a resin such as an adhesive and a solvent on the surface of the carrier film and then heating to remove the solvent. The ceramic sheet is formed as a ceramic green sheet (ceramic green sheet) by, for example, applying a slurry prepared by dispersing ceramic powder and a binder agent in a solvent onto a carrier film and then removing the solvent by heating. It

Organic solvents have hitherto been used as the above-mentioned solvents. However, recently, water is often used instead of the organic solvent. That is, an aqueous solution of an adhesive such as an emulsion is used for the coating liquid containing the adhesive,
A water-dispersed slurry has come to be used for coating the slurry. The reason for this is that water does not pose a risk of fire or environmental pollution like an organic solvent, and therefore it becomes extremely easy to handle the chemical solution in the step of adjusting the concentration of the solution or slurry, the step of coating or the step of removing by heating.

However, the surface tension of water is larger than that of organic solvents (the surface tension γL of water is about 73 dyne / cm), and the release layer having a small surface energy (for example, the surface tension (γS) of the silicone release layer is (19 to 21 dyne / cm) When an aqueous coating solution such as an aqueous solution of an adhesive or a water-dispersed slurry is applied onto the surface of the release layer, the coating solution is not uniformly applied and is dispersed in droplets (so-called cissing). It becomes a big problem to be in a state. In order to improve this problem, a method of increasing the viscosity of the coating liquid (resin solution or slurry) or a method of adding a surfactant or the like to reduce the surface tension of the coating liquid can be considered. However, the method of increasing the viscosity has the drawbacks that leveling during coating is difficult and the thickness of the coating film is not uniform, and that it is difficult to thin the resin sheet, the resin coating, the ceramic sheet, or the like. Further, when a surfactant is blended, there is a problem that the sheet strength after the sheet is reduced and a stable product may not be obtained depending on the type and amount thereof.

[0006]

The object of the present invention is to solve the above-mentioned drawbacks of the prior art and to prevent cissing even if an aqueous coating solution is used for coating (good wettability). It is intended to provide a release film having the above-mentioned properties and capable of being peeled off from various pressure-sensitive adhesive films, resin sheets, ceramic sheets and the like with an appropriate force (good releasability).

[0007]

The object of the invention is, according to the invention, on at least one side of a plastic film,
Organic resin consisting of alkyd resin, acrylic resin and melamine resin (however, in the organic resin, alkyd resin
Melamine for 100 parts by weight of resin and acrylic resin in total
Resin is 10 to 200 parts by weight, and alkyd resin 1
Acrylic resin is 50 to 300 parts by weight with respect to 00 parts by weight.
It is achieved by a release film provided with a release layer whose main component is a resin composition obtained by mixing 1 to 30 parts by weight of a silicone resin with respect to 100 parts by weight. Hereinafter, the present invention will be described in detail.

[Plastic Film] The plastic film used as the film substrate in the present invention is not particularly limited, but preferred examples include polyester film, polyolefin film such as polyethylene and polypropylene, polyvinyl chloride film and the like. Among these plastic films, the polyester film, which is excellent in heat resistance and dimensional stability of the film, is particularly preferable.

As the above-mentioned polyester film, a polyester film having good transparency is preferably used for applications requiring transparency, and a biaxially stretched polyester film is particularly preferable. For applications requiring light-shielding properties, a polyester film containing an inorganic pigment is preferably used, and a biaxially stretched polyester film containing a pigment such as TiO ₂ or SiO ₂ is particularly preferable.

The polyester constituting the polyester film is preferably a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component. For example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene- 2,6-naphthalene dicarboxylate and the like can be mentioned. Further, it may be a copolymer in which a part of these is substituted with another component, or a mixture with a polyalkylene glycol or another resin.

The above polyester film is preferably a biaxially stretched film, but this biaxially stretched film can be manufactured by a known method. For example, the polyester is dried and then melted, and then a die (for example, T-die, I-die, etc.)
From the above to a cooling drum and rapidly cooled to obtain an unstretched film, which is then stretched in the longitudinal direction in the range of 2 to 5 times and then in the transverse direction in the range of 2 to 5 times. Further, it can be produced by further heat fixing at 160 to 260 ° C. The film thickness is not particularly limited, but 5
˜200 μm is desirable.

The plastic film may contain a lubricant, for example, inorganic fine particles such as calcium carbonate, kaolin, silica, titanium oxide, etc. in order to improve the slipperiness and processability of the film. Further, other additives such as stabilizers, ultraviolet absorbers, flame retardants, antistatic agents and the like may be contained.

[Release Layer] In the present invention, a release layer containing a resin composition obtained by blending an organic resin and a silicone resin as a main component is provided on at least one surface of the plastic film.

The organic resin is composed of an alkyd resin, an acrylic resin and a melamine resin, and the mixing ratio thereof is preferably 10 to 200 parts by weight with respect to 100 parts by weight of the alkyd resin and the acrylic resin.

Of the resin composition of the present invention, the alkyd resin and the acrylic resin form a copolymer with at least a part of the silicone resin by blending with the silicone resin, and the melamine resin mainly undergoes a crosslinking reaction with the alkyd resin. It acts to cure the release layer.

The above-mentioned alkyd resin has a skeleton of a condensate of polybasic acid such as phthalic anhydride as an acid component and polyhydric alcohol such as glycerin or ethylene glycol as a glycol component, which is a fatty acid such as a drying oil. It is a resin modified by. For example, castor oil-modified alkyd resin, soybean oil-modified alkyd resin, linseed oil-modified alkyd resin and the like are used, but various fatty acid-modified alkyd resins can be used in any combination. In the resin composition of the present invention, for example, a silicone resin can be blended during or after the production of the alkyd resin, and the silicone resin can be graft-copolymerized with the alkyd resin. At this time, the blending ratio of the alkyd resin and the silicone resin is preferably 1 to 30 parts by weight of the silicone resin, particularly 5 to 100 parts by weight of the alkyd resin.
It is preferably 10 parts by weight.

The acrylic resin is blended in order to make the release layer tough, and to improve the wettability of the release layer surface. As the acrylic resin, for example, polyacrylic acid, polymethacrylic acid, polymethylmethacrylate, or the like can be used. The mixing ratio of the alkyd resin and the acrylic resin can be changed according to the purpose because various physical properties can be obtained depending on the mixing ratio, but the acrylic resin is used in a ratio of 50 to 300 parts by weight with respect to 100 parts by weight of the alkyd resin. It is preferable.

As the melamine resin, for example, methylated melamine resin, butylated melamine resin, methylated urea melamine resin and the like can be used. The mixing ratio of the melamine resin to the alkyd resin and the acrylic resin is preferably 10 to 200 parts by weight of the melamine resin with respect to 100 parts by weight of the alkyd resin and the acrylic resin. An acid catalyst such as sodium p-toluenesulfonate can be used as a curing catalyst for this crosslinking reaction.

The silicone resin is a polymer having a basic skeleton made of polydimethylsiloxane, but preferably has a phenyl group, an alkyl group or the like at the terminal or side chain in order to improve the compatibility with the alkyd resin and the like.

[Method for coating release layer] In the present invention,
The release layer is provided on at least one surface of the plastic film. For the release layer, for example, a coating liquid containing the components constituting the release layer is applied to the film, dried by heating and cured to form a coating film. It can be applied by coating. As a coating method of this coating liquid, any known coating method can be applied, and examples thereof include a roll coating method, a blade coating method and a bar coating method, but are not limited to these methods. . Further, the thickness of the release layer after coating and drying is preferably 0.02 to 50 μm, and particularly preferably 0.1 to 1 μm.

[Adhesive Layer] In the present invention, an adhesive layer is provided on at least one side of the plastic film in order to enhance the adhesion between the plastic film and the release layer, and a release layer is further laminated on the adhesive layer. can do. For this adhesive layer, for example, a silane coupling agent can be used. The silane coupling agent is represented by the general formula Y-
Examples thereof include those represented by Si-X3. Here, Y represents a functional group represented by, for example, an amino group, an epoxy group, a vinyl group, a methacryl group, a mercapto group, and X represents a hydrolyzable functional group represented by an alkoxy group.
The preferable thickness of the adhesive layer is about 0.01 to 5 μm, and particularly about 0.02 to 2 μm.

[0022]

EXAMPLES The present invention will be further described below with reference to examples. The characteristic values of the film were measured by the following methods.

1. Wettability of water-based paint A ceramic powder dispersion slurry having the following composition is prepared. (A) Ceramic powder (barium titanate): 100 parts by weight (b) Water-soluble acrylic emulsion: 9 to 13 parts by weight (c) Water-soluble polyurethane resin: 1 part by weight (d) Ammonium polycarboxylate: 1 part by weight (E) Water: 10 to 20 parts by weight (f) Ammonia: 1 part by weight A ceramic powder dispersion slurry is prepared with a ball mill.
The Hegman grind gauge is used so that the dispersed state is 7 or more. Next, this ceramic powder dispersed slurry is applied to the release layer surface of the release film using a straight edge applicator having a gap of 1 mil,
After drying at 110 ° C. for 2 minutes, the degree of cissing on the coated edge was observed and the cissing resistance of the solvent-based paint was evaluated according to the following criteria.

[0024] A: Repelling is not observed ... Good wettability B: Some repelling is observed ... Slightly good wettability C: Repelling is observed ... Poor wettability

2. Peelability of ceramic sheet The peeling state when the ceramic sheet formed by the method described in the above section (1. Wetting property of water-based paint) is peeled from the release film is observed and the peelability is evaluated according to the following criteria. did.

A: Easy peeling: Good peeling property B: Peeling strength is large and the sheet breaks when pulled quickly. Peeling property is slightly good. C: Sheet breaks .. Poor peeling property D: Repelling. Cannot be made into a sheet because it is ... extremely defective

3. Residual adhesion rate polyester adhesive tape (Knit-31B)
Cold rolled stainless steel plate (SUS3 specified in G4305
The peeling force after being adhered to 04) is measured, and is taken as the basic adhesive force (f ₀ ). Further, the polyester adhesive tape is pressure-bonded to the release layer coated surface of the film sample with a 2 kg pressure roller, left for 30 seconds, and then the adhesive tape is peeled off.
Then, the peeled adhesive tape is attached to the above-mentioned stainless steel plate, and the peeling force of the bonded portion is measured to obtain the residual adhesive force (f). The residual adhesion ratio is calculated from the obtained basic adhesive force (f ₀ ) and residual adhesive force (f) using the following formula.

[0028]

## EQU1 ## Residual adhesion rate (%) = (f / f ₀ ) × 100 The preferred range of the residual adhesion rate is 85% or more. When the residual adhesion ratio is less than 85%, for example, when the release film is wound into a roll and stored, the components constituting the release layer are transferred to the surface of the adjacent film (so-called back surface transfer).
However, the wettability and releasability of the release layer may be deteriorated, which is not preferable.

Example 1 100 parts by weight of alkyd resin (coconut oil modified alkyd resin), 200 parts by weight of acrylic resin (polyacrylic acid), 50 parts by weight of melamine resin (butylated melamine resin) and silicone resin (polyphenylmethyl). Siloxane) 35 parts by weight (ratio of 10 parts by weight of silicone resin to 100 parts by weight of organic resin) is mixed to obtain a resin composition, which is dissolved in a mixed solvent of methyl ethyl ketone, methyl isobutyl ketone and toluene,
A solution having a total solid content concentration of 3% by weight was prepared. Next, an acid catalyst (paratoluenesulfonic acid) was added to the above solution as a curing reaction accelerator to prepare a coating liquid.

A coating amount of 6 g / m 2 was applied to a biaxially stretched polyethylene terephthalate film having a thickness of 50 μm.
It was applied by (wet) and dried and cured at a heating temperature of 140 ° C. for 1 minute to prepare a release film having a release layer thickness of 0.3 μm. The characteristics of this release film are shown in Table 1.

Example 2 100 parts by weight of alkyd resin (castor oil modified alkyd resin), 100 parts by weight of acrylic resin (polyethyl acrylate), 100 parts by weight of melamine resin (butylated melamine resin) and silicone resin (hydroxyl group). Substituted diphenyl polysiloxane) 75
Parts by weight (2 parts by weight of silicone resin for 100 parts by weight of organic resin)
The resin composition obtained by mixing 5 parts by weight) is dissolved in a mixed solvent of methyl ethyl ketone, methyl isobutyl ketone and toluene, and the total solid content concentration is 3% by weight.
A solution of was prepared. Next, an acid catalyst (paratoluenesulfonic acid) was added to the above solution as a curing reaction accelerator to prepare a coating liquid.

A coating amount of 6 g / m 2 was applied to a biaxially stretched polyethylene terephthalate film having a thickness of 50 μm.
It was applied by (wet) and dried and cured at a heating temperature of 140 ° C. for 1 minute to prepare a release film having a release layer thickness of 0.3 μm. The characteristics of this release film are shown in Table 1.

Example 3 100 parts by weight of alkyd resin (castor oil-modified alkyd resin), 200 parts by weight of acrylic resin (100 parts by weight of polyacrylic acid and 100 parts by weight of polyethyl methacrylate), melamine resin (butylated melamine resin) ) 100 parts by weight and 80 parts by weight of silicone resin (hydroxyl group-substituted diphenylpolysiloxane) (ratio of 20 parts by weight of silicone resin to 100 parts by weight of organic resin) are mixed to obtain methyl ethyl ketone, methyl isobutyl ketone. And was dissolved in a mixed solvent of toluene to prepare a solution having a total solid content concentration of 3% by weight. Next, an acid catalyst (paratoluenesulfonic acid) was added to the above solution as a curing reaction accelerator to prepare a coating liquid.

A coating amount of 6 g / m 2 was applied to a biaxially stretched polyethylene terephthalate film having a thickness of 50 μm.
It was applied by (wet) and dried and cured at a heating temperature of 140 ° C. for 1 minute to prepare a release film having a release layer thickness of 0.3 μm. The characteristics of this release film are shown in Table 1.

[Comparative Example 1] A curable silicone (KS847 (H) manufactured by Shin-Etsu Chemical Co., Ltd.) of a type in which a platinum catalyst is added to a mixed solution of polydimethylsiloxane and dimethylhydrogensilane to carry out an addition reaction with methyl ethyl ketone, It was dissolved in a mixed solvent of methyl isobutyl ketone and toluene to prepare a solution having a solid content concentration of 2%.

This solution was coated on the biaxially stretched polyethylene terephthalate film at a coating amount of 6 g / m 2 (wet) and dried and cured at a heating temperature of 140 ° C. for 1 minute to give a release layer of 0 thickness. A release film of 0.15 μm was prepared. The characteristics of this film are shown in Table 1.

[Comparative Example 2] A resin composition obtained by mixing 100 parts by weight of an alkyd resin (coconut oil modified alkyd resin) and 40 parts by weight of a melamine resin (butylated melamine resin) with methyl ethyl ketone, methyl isobutyl ketone and toluene. Was dissolved in the mixed solvent of to prepare a solution having a total solid content concentration of 3% by weight. Next, an acid catalyst (paratoluenesulfonic acid) was added to the above solution as a curing reaction accelerator to prepare a coating liquid.

A coating amount of 6 g / m 2 was applied to a biaxially stretched polyethylene terephthalate film having a thickness of 50 μm.
It was applied by (wet) and dried and cured at a heating temperature of 140 ° C. for 1 minute to prepare a release film having a release layer thickness of 0.3 μm. The characteristics of this release film are shown in Table 1.

Comparative Example 3 100 parts by weight of alkyd resin (castor oil modified alkyd resin), 100 parts by weight of acrylic resin (polyacrylic acid), 100 parts by weight of melamine resin (butylated melamine resin) and silicone resin (hydroxyl group substitution) Diphenyl polysiloxane) 150 parts by weight (50 parts by weight of silicone resin to 100 parts by weight of organic resin) are mixed to obtain a resin composition, which is dissolved in a mixed solvent of methyl ethyl ketone, methyl isobutyl ketone and toluene, A solution having a solid content concentration of 3% by weight was prepared. Next, an acid catalyst (paratoluenesulfonic acid) was added to the above solution as a curing reaction accelerator to prepare a coating liquid.

A coating amount of 6 g / m 2 was applied to a biaxially stretched polyethylene terephthalate film having a thickness of 50 μm.
It was applied by (wet) and dried and cured at a heating temperature of 140 ° C. for 1 minute to prepare a release film having a release layer thickness of 0.3 μm. The characteristics of this release film are shown in Table 1.

[0041]

[Table 1]

As is clear from Table 1, the release films of the present invention shown in the examples are excellent in surface wettability, that is, cissing resistance to water-based paint, releasability of resin sheet, and non-migration property of coating film. It was a thing.

[0043]

EFFECTS OF THE INVENTION The release film of the present invention is used for forming various types of films and sheets by using a film obtained by curing a resin composition composed of an alkyd resin, an acrylic resin, a melamine resin and a silicone resin as a release layer. Excellent in wettability when used with water-based coating liquid, and also excellent in releasability from various resin sheets, resin coatings, ceramic sheets, etc., so for forming protective films for adhesive coatings, resin sheets, resin coatings, ceramic sheets, etc. It is useful as a carrier film.

─────────────────────────────────────────────────── --Continued from the front page (56) Reference JP-A-7-137218 (JP, A) JP-A-3-17146 (JP, A) JP-A-7-242829 (JP, A) JP-A-51- 125102 (JP, A) JP 54-119533 (JP, A) JP 6-23746 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B32B 1/00-35 / 00

Claims (2)

(57) [Claims] 1. An organic resin comprising an alkyd resin, an acrylic resin and a melamine resin on at least one side of a plastic film (provided that the organic resin is an alkyl resin).
For total 100 parts by weight of resin and acrylic resin,
The lamin resin is 10 to 200 parts by weight.
50 to 300 parts by weight of acrylic resin for 100 parts by weight of fat
Parts) 100 parts by weight of silicone resin 1 to 3
A release film provided with a release layer containing a resin composition obtained by blending 0 part by weight as a main component. 2. The release film according to claim 1, wherein the organic resin comprises 10 to 200 parts by weight of a melamine resin with respect to 100 parts by weight of an alkyd resin and an acrylic resin.