JP3258057B2 - Silicone easily adhesive film and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily adhesive silicone film and a method for producing the same, and more particularly, to a polyester film which enhances the reactivity of a silane coupling agent and has excellent silicone adhesive properties, and a method for producing the same.

[0002]

2. Description of the Related Art A release film is used for protecting an adhesive surface formed of an adhesive, an adhesive, a patch, or the like, or for curing a resin such as a urethane resin, an epoxy resin, or an unsaturated polyester resin. It is used for the purpose of protecting formability, etc., and its amount is expanding.

Conventionally, as such a release film, at least one surface of a polyester film provided with a film made of an addition-polymerized cured product of a silicon compound having a vinylsiloxane group or a condensation-polymerized cured product of an alkyloxysilane or an oxysilane compound. Is used. This cured product has the advantage of being non-adhesive and having an excellent releasing effect, and also having an excellent thermal stability, but has a problem that the adhesion with the polyester film as the base film is not sufficient and the durability is low. .

Therefore, as a method for improving the adhesion between the silicone layer and the polyester film, Japanese Patent Application Laid-Open No.
No. 5838 proposes a method of providing a crosslinked primer layer of a silane coupling agent. However, there is a problem that the reactivity of the silane coupling agent is slow and the productivity is low. In order to improve the reactivity, a platinum-based catalyst or the like is added in a solvent system, but this catalyst is hardly soluble in water or tends to lose catalytic activity when dissolved. Is not suitable.

In order to improve the adhesiveness between the polyester film and the release layer, there is a method of using a silicone-modified urethane or an acrylic resin as the release layer. However, in this case, there is a disadvantage that the original release property is poor. .

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a silicone-adhesive polyester film having excellent adhesiveness to silicone.

Another object of the present invention is to provide a method for producing the above-mentioned silicone easily adhesive polyester film with high productivity.

[0008]

The present invention has the following structure to achieve the above object. 1. An easily-adhesive polyester film having a crosslinked primer layer comprising a silane coupling agent and alkaline inorganic fine particles on at least one surface of the polyester film. 2. A primer coating solution containing a silane coupling agent and alkaline inorganic fine particles and having a pH adjusted to 4.0 to 7.0 is applied to at least one surface of the polyester film, and then dried and thermally crosslinked to form a crosslinked primer layer. A method for producing a silicone easily-adhesive polyester film, comprising:

The polyester in the present invention is a crystalline 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, polybutylene terephthalate, polyethylene-2,6-naphthalate, poly (1,4-cyclohexylene dimethylene terephthalate) and the like. Further, a copolymer in which some of these components are substituted with other components, or a mixture with polyalkylene glycol or another resin may be used.

[0010] The polyester film in the present invention comprises:
It can be manufactured by a conventionally known method. For example, the above polyester is dried and then melted, and a die (for example, T die, I
A non-stretched film by extruding the film from a die or the like onto a cooling drum, stretching the unstretched film biaxially, and heat-setting the film. The thickness of the film is not particularly limited, but is preferably 12 to 250 μm. As the polyester film, a film containing no lubricant is preferable from the viewpoint of surface flatness. However, a lubricant such as inorganic fine particles such as calcium carbonate, kaolin, silica and titanium oxide and / or precipitated fine particles of catalyst residue are used for controlling the surface roughness. It may be a film containing
Further, a film containing other additives such as an antistatic agent such as sodium dodecylbenzenesulfonate and a color tone adjusting agent may be used.

[0011] Silane constituting the primer layer of the present invention
The coupling agent has the general formula YRSix _ThreeA compound represented by
Things. Here, Y is a vinyl group, an epoxy group, an amino
Group, an organic functional group such as a mercapto group, R is methylene,
An alkylene group such as ethylene and propylene;
Hydrolyzable groups such as xy group and ethoxy group and alkyl groups
It is. Specific compounds include, for example, vinyl trieth
Xysilane, vinyltrimethoxysilane, γ-glycid
Xypropyltrimethoxysilane, γ-glycidoxyp
Propyl methyldiethoxysilane, N-β (aminoethyl
) -Γ-aminopropyltrimethoxysilane, N-β
(Aminoethyl) -γ-aminopropylmethyldimethoxy
Sisilane, γ-mercaptopropyltrimethoxysilane
And the like. Preferred silane coupling
As the agent, water-soluble or water-dispersible coupling
Agent.

The alkaline inorganic fine particles constituting the primer layer together with the silane coupling agent include, for example, iron oxide sol, alumina sol, tin oxide sol, zirconium oxide sol, silica sol and the like, with alumina sol and silica sol being particularly preferred. Among them, silica sol is preferred from the viewpoint of promoting the initial reactivity (dimerization, trimerization, etc.) of the silane coupling agent.

The alkaline inorganic fine particles preferably have a small particle diameter having a large surface area, and preferably have an average particle diameter of 1 to 150 nm, more preferably 2 to 100 nm, particularly preferably 3 to 50 nm. If the average particle size is larger than 150 nm, the surface area becomes too small, the effect of accelerating the reaction of the silane coupling agent is reduced, and the surface of the primer layer is unfavorably roughened. On the other hand, when the average particle size is smaller than 1 nm,
The surface area is too large, and it is difficult to control the reaction of the silane coupling agent, which is not preferable.

The amount of the alkaline inorganic fine particles is 1 to 50% by weight, more preferably 2 to 50% by weight, based on the amount of the silane coupling agent.
Preferably, it is about 20% by weight. This amount is 1% by weight
If the amount is less than 50% by weight, the crosslinking reaction does not proceed. On the other hand, if the amount exceeds 50% by weight, the stability of the coating solution is lacking.

A primer coating solution containing a silane coupling agent and alkaline inorganic fine particles, particularly an aqueous coating solution, has a pH of 4.0 to 7.0, preferably 5.0 to 7.0.
Adjust to 6.7. If the value of p is less than 4.0, the catalytic activity of the inorganic fine particles is lost. On the other hand, if the value of p exceeds 7.0, the coating liquid becomes unstable and precipitates, which is not preferable.

As the acid for adjusting the pH, inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid, and organic acids such as oxalic acid, formic acid, citric acid and acetic acid are used, and organic acids are particularly preferable.

After the application, a necessary amount of a surfactant such as an anionic surfactant, a cationic surfactant, or a nonionic surfactant can be added to the aqueous liquid. As such a surfactant, the surface tension of the coating solution is 50
dyne / cm or less, preferably 40 dyne / cm or less, which promotes wetting to the polyester film is preferable. For example, polyoxyethylene alkylphenyl ether, polyoxyethylene-fatty acid ester, sorbitan fatty acid ester, glycerin fatty acid ester, fatty acid Examples include metal soaps, alkyl sulfates, alkyl sulfonates, alkyl sulfosuccinates, quaternary ammonium chloride salts, and alkylamine hydrochlorides. Further, other additives such as an antistatic agent, an ultraviolet absorber, a pigment, an organic filler, a lubricant, and an anti-blocking agent can be mixed as long as the effects of the present invention are not lost.

Such a primer coating solution is applied to at least one side of a polyester film, and then dried and thermally crosslinked to provide a crosslinked primer layer. The application may be carried out in a usual primer application step, that is, a step of applying to a polyester film which has been biaxially stretched and heat-set, separated from the production step of the film. However, in this step, it is desirable to apply the coating in a clean atmosphere because refuse, dust and the like are easily involved. From such a viewpoint, coating in the polyester film production process is preferable. In particular, it is preferable to apply an aqueous coating solution to one or both surfaces of the polyester film before the crystal orientation is completed in this step.

Here, the polyester film before the completion of the crystal orientation refers to an unstretched film obtained by hot-melting a polyester to form a film as it is: the unstretched film is stretched in a longitudinal direction (longitudinal direction) or a transverse direction (width direction). ) Uniaxially stretched film oriented in either direction; furthermore, low-magnification stretched orientation in two directions, longitudinal and transverse (finally re-stretched in the longitudinal or transverse direction to complete orientation crystallization) Biaxially stretched film).

The solid content of the coating solution is usually 30% by weight or less, more preferably 10% by weight or less. The coating amount is 0.5 to ²⁰ g, preferably 1 to 10 g, per m ² of the running film.

As a coating method, any known coating method can be applied. For example, kiss coat method, berth coat method,
A die coating method, a reverse coating method, an offset gravure coating method, a myrbar coating method, a gravure coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like may be used alone or in combination.

The polyester film to which the coating liquid has been applied and before the completion of the crystal orientation is dried and led to steps such as stretching and heat setting. For example, a vertically uniaxially stretched polyester film coated with an aqueous liquid is guided to a stenter, and is horizontally stretched and heat-set. During this time, the coating solution is dried and thermally crosslinked.

Conditions for oriented crystallization of the polyester film,
For example, stretching, heat setting, and the like can be performed under conditions conventionally accumulated in the art.

The crosslinked primer layer in the present invention exhibits excellent adhesion to polyester film and also exhibits excellent adhesion to silicone. Therefore, using the silicone easily adhesive polyester film of the present invention,
For example, when a silicone release layer is provided on the crosslinked primer layer, a release film having excellent durability can be obtained.

For the silicone release layer, for example, a polyorganosiloxane having an unsaturated hydrocarbon group such as a vinyl group and a polyorganosiloxane having a hydrogen atom directly bonded to a silicon atom are subjected to an addition reaction using a platinum compound as a catalyst. Cured film, and a polyorganosiloxane having a hydroxyl group bonded to a silicon atom and an organosilane or polysiloxane having a hydrolyzable group (for example, an alkoxy group, an oxime group, an acetoxy group, etc.) are treated with an organotin or organotitanium compound. Preferred examples of the catalyst include a cured film obtained by a condensation reaction.

Such a cured film is formed by applying a coating solution for forming the film on a primer layer and curing the primer layer. Silicone for film formation
For example, a coating solution is prepared by dissolving in a solvent such as toluene, ethyl acetate, n-hexane, methyl ethyl ketone, or cyclohexanone, and it is preferable to add a trace amount of a catalyst such as an organoplatinum compound for promoting the polymerization reaction to the coating solution. . As a method for applying the coating solution, various coating methods such as a spinner coating method, a spray coating method, a bar coating method, a gravure coating method, and a reverse coating method are used.

The thickness of the silicone release layer is in a dry state,
It is preferably from 0.01 to 10 μm, more preferably from 0.02 to 5 μm. When the thickness is less than 0.01 μm, the releasability is insufficient, and when the thickness is more than 10 μm, transfer of silicone to the pressure-sensitive adhesive due to insufficient polymerization is unfavorable.

The release film has excellent adhesiveness between the polyester film and the silicone release layer, has little transfer of the release layer component to an adhesive or the like, and has excellent durability.

The silicone adhesive polyester film of the present invention is not restricted by the properties of the silicone provided on the crosslinked primer layer, and various applications can be expected depending on the properties of the silicone.

[0030]

The present invention will be described in more detail with reference to the following examples. In the examples, “parts” means “parts by weight”.

[0031]

Examples 1 to 8 and Comparative Examples 1 to 3 Melt extrusion of polyethylene terephthalate (containing 500 ppm of lubricant) having an intrinsic viscosity of 0.65 measured in O-chlorophenol at 35 ° C. onto a rotating cooling drum maintained at 20 ° C. 950μ thick
m of unstretched film, and then stretched 3.5 times in the machine axis direction, and the silane coupling agent, inorganic fine particles and nonionic surfactant (polyoxyethylene nonyl phenyl ether) ), And 4 wt% solids concentration adjusted to pH 6.3 with citric acid
Was applied by a kiss coat method. Continue 10
The film was stretched 3.9 times in the transverse direction at 5 ° C. and further heat-treated at 210 ° C. to obtain a 75 μm thick primer-coated polyester film.

On the other hand, KS-772 (trade name, a product of Shin-Etsu Chemical Co., Ltd.) of a type in which a platinum catalyst is added to a mixture of polydimethylsiloxane and methylhydrogenpolysiloxane to cause an addition reaction and cure, is dissolved in toluene and the solid content 5
% Solution was made.

This solution was coated on the above-mentioned primer-coated polyester film at a coating amount of 1 g / m ² ,
Perform a drying and curing reaction at 50 ° C. and a residence time of 1 minute,
I made a release film.

Table 2 shows the quality of the release film.

The transferability of the release layer and the adhesiveness of the polyester were determined by the following methods.

(1) Back transferability A polyester film is overlaid on the coating surface,
After applying a constant load, draw a line with magic ink on the polyester film surface in contact with the coating surface, and check the degree of "repelling".

(2) Release Property A cellophane tape having a width of 24 mm was pressure-bonded to the coated surface with a rubber roll, and then 180 ° with an Instron type tensile tester.
The film is peeled in the direction, and is indicated by the resistance value (g / 24 mm) at this time.

(3) Silicone Easy Adhesion (A) Initial Easy Adhesion The coating surface of the release film immediately after coating and drying is rubbed several times with a fingertip, and the film is peeled off and the adhesion is observed. (B) Easy-durability adhesiveness After leaving the release film in an atmosphere of 60 ° C. × 80% RH for one week, the coating surface is rubbed with a fingertip in the same manner as the initial easy-adhesion, and the detachment adhesion of the film is observed.

[0039]

【Evaluation criteria】

 …: No change in the silicone coating film △: slight whitening ×: almost whitening ×: the silicone layer completely disappears.

[0040]

[Table 1]

[0041]

[Table 2]

As is clear from Table 2, the release film using the silicone-adhesive film of the present invention is excellent in durable silicone-adhesiveness.

[0043]

According to the present invention, it is possible to provide an easily-adhesive polyester film exhibiting excellent adhesiveness to silicone, and a method for producing the film with high productivity.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁷ Identification code FI B32B27 / 36 B32B27 / 36 (56) References JP-A-64-5838 (JP, A) JP-A-60-219054 (JP) , A) JP-A-60-219053 (JP, A) WO 91/16999 (WO, A1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J ^7/ 00-7/18 B32B 27 / 00-27/42

Claims (6)

(57) [Claims] 1. An easily-adhesive polyester film having a crosslinked primer layer comprising a silane coupling agent and alkaline inorganic fine particles provided on at least one surface of the polyester film. 2. The amount of the alkaline inorganic fine particles is 1 to 50% by weight based on the amount of the silane coupling agent.
The easily-adhesive silicone polyester film according to claim 1 , wherein the average particle size of the inorganic fine particles is in the range of 1 to 150 nm . 3. A release film laminated with a silicone release layer.
3. The silicone according to claim 1, which is used for a system.
Easy-adhesive polyester film. 4. A primer coating solution containing a silane coupling agent and alkaline inorganic fine particles and having a pH adjusted to 4.0 to 7.0 is applied to at least one surface of the polyester film, and then dried and thermally crosslinked. And forming a crosslinked primer layer on the silicone film. 5. The method for producing a silicone-adhesive polyester film according to claim 4 , wherein the polyester film to which the primer coating solution is applied is a polyester film before the crystal orientation is completed. 6. The amount of the alkaline inorganic fine particles is 1 to 50% by weight based on the amount of the silane coupling agent.
6. The method for producing a silicone-adhesive polyester film according to claim 5 , wherein the average particle diameter of the conductive inorganic fine particles is in the range of 1 to 150 nm .