JPH11254597A - Silicone easily adhesive polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a silicone easily adhesive film having excellent antistatic properties and excellent adhesive properties to a silicone. SOLUTION: The silicone easily adhesive polyester film is obtained by coating at least one side surface of a polyester film before a crystal orientation is completed with a coating liquid containing an alkoxysilane having an epoxy group, an alkoxysilane having an amino group and a cationic surfactant, drying it, orienting it and heat treating it, thereby obtaining a crosslinked primer layer.

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 polyester film, and more particularly, to an easily-adhesive polyester film having excellent releasability, excellent silicone easy-adhesion, and antistatic properties.

[0002]

2. Description of the Related Art A release film is used as a protective film for an adhesive surface such as an adhesive, an adhesive or a patch, or a sheet of a curable resin such as a urethane resin, an epoxy resin or an unsaturated polyester resin, or a sheet of a thermoplastic resin. It is used as a carrier sheet for molding, and its amount is expanding.

[0003] As such a release film, conventionally,
A polyester film provided on at least one side with a coating made of an addition-polymerized cured product of a silicone compound having a vinylsiloxane group, a condensation-polymerized cured product of an alkyloxysilane or an oxysilane compound, or the like is used. This cured product has the advantage of being non-adhesive and having an excellent releasing effect, but has the problem that the adhesion to the polyester film as the base film is insufficient and the durability of the coating film is low.

Therefore, as a method for improving the adhesion between the silicone layer and the polyester film, there has been proposed a method of providing a cross-linking primer layer of a silane coupling agent (JP-A-1-5838). However, this method has a problem that the reactivity of the silane coupling agent is low and the productivity is low. In order to improve this reactivity, a solvent such as a platinum-based catalyst has been added.
This catalyst has a disadvantage that it is hardly soluble in water or loses its catalytic activity even when dissolved, and is not suitable for an aqueous coating solution.

In addition, the crosslinked primer layer of the silane coupling agent is very easily charged, it is difficult to handle in the production process, and the film after coating the silicone layer is also easily charged, and the releasability becomes poor. is there.

There is also a method of using a silicone-modified urethane or an acrylic resin as a release layer to improve the adhesion between the polyester film and the silicone layer. However, this method is inferior in the release property of the release layer. There are inherent disadvantages.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve such a problem and to provide an easily adhesive silicone film having excellent adhesion to silicone.

[0008]

According to the present invention, at least one side of the polyester film before the crystal orientation is completed,
A coating liquid containing an alkoxysilane having an epoxy group (A), an alkoxysilane having an amino group (B) and a cationic surfactant (C) is applied, and a crosslinked primer layer obtained by drying, stretching and heat treatment is provided. The main feature is a silicone easy-adhesive polyester film.

Hereinafter, the present invention will be described in detail. The polyester constituting the polyester film of the present invention is a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof.

Specific examples of such polyesters include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), polyethylene 2,6-naphthalenedicarboxylate, and the like. Or a mixture of these with a small proportion of another resin.

[0011] Of these, polyethylene terephthalate, if higher strength and heat resistance are required, use polyethylene-
Preferred is 2,6-naphthalenedicarboxylate.

The polyester used in the present invention contains an inorganic or organic lubricant such as silicon dioxide, calcium carbonate, kaolin, or silicone particles having a particle size of 0.1 to 5 μm.
It is preferably contained in an amount of from 03 to 3.0% by weight, more preferably from 0.1 to 1.0% by weight.

The polyester used in the present invention may contain a stabilizer, a colorant, an antioxidant, and other additives as required, so long as the original performance is not impaired.

The polyester film of the present invention comprises:
It can be manufactured by a known method. For example, in the case of a polyethylene terephthalate film, the polyethylene terephthalate is melt-extruded into a film, wound around a casting drum, cooled and solidified to form an unstretched film.
The unstretched film is heated to 80 to 150 ° C. and stretched once or twice or more in the longitudinal direction so that the total magnification becomes 3 to 7 times. Thereafter, the film is stretched at 90 to 150 ° C. so that the width direction becomes 3 to 5 times.
The heat treatment is performed at 0.1 ° C. for 0.1 to 10 seconds, and the re-heat treatment is performed at a temperature lower by 10 to 20 ° C. than the heat treatment temperature while shrinking by 2 to 20% in the width direction.

Although the thickness of the polyester film in the present invention is not limited, it is 5 to 200 μm, and more preferably 25 to 200 μm.
It is preferably 100 μm.

The polyester film of the present invention is coated on at least one surface thereof with a coating liquid containing an alkoxysilane having an epoxy group (A), an alkoxysilane having an amino group (B) and a cationic surfactant (C). It is necessary to. This coating layer is necessary for increasing the adhesion between the silicone and the polyester film and for imparting antistatic properties.

The alkoxysilane having an epoxy group (A) in the present invention is a compound represented by XRSiZ ₃ . X is a functional group having an epoxy ring, R is an alkylene group such as a methylene group, an ethylene group or a propylene group, Z is a hydrolyzable functional group such as a methoxy group or an ethoxy group, an alkyl group and / or It represents an organic functional group having these groups.

Specific examples of the alkoxysilane (A) preferably include, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane and the like. be able to.

The alkoxysilane having an amino group (B) in the present invention is a compound represented by YRSiZ ₃ . Note that Y is a functional group having an amino group, R is an alkylene group such as a methylene group, an ethylene group, or a propylene group;
Z is a hydrolyzable functional group such as a methoxy group and an ethoxy group, an alkyl group and / or an organic functional group having these groups.

Specific examples of the alkoxysilane (B) include, for example, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β (aminoethyl) -γ-
Preferred are aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane and the like.

The cationic surfactant (C) in the present invention has an effect as an antistatic agent. An anionic surfactant is not preferred because it reacts with the alkoxysilane (B) having an amino group and precipitates in the coating solution, and a nonionic surfactant is not preferred because sufficient antistatic properties cannot be obtained.

Examples of the cationic surfactant include the following:
Quaternary ammonium salts such as quaternary ammonium sulfate and quaternary ammonium nitrate are preferable, and specific examples thereof include compounds having the following structures.

[0023]

Embedded image

(Where R ₁ , R ₂ , R ₃ , and R ₄ are each a substituent selected from an alkyl group having 1 to 30 carbon atoms, a polyoxyethylene group, an alkyl group including a hydroxyl group, and a benzyl group. There may be the same or different from each .X - ^(counterion) represents an ethosulfate ion or nitrate ion).

The cationic surfactant (C) preferably does not contain a halogen element. When halogen is contained, rust is generated on the mechanical equipment, and the service life of the equipment may be shortened. Furthermore, when products are incinerated and disposed of, harmful gases are generated, which may have an adverse effect on the human body.

In the present invention, the weight ratio of the alkoxysilanes (A) and (B) to the cationic surfactant (C) is as follows:
It is preferably within the range of the following formulas (1) and (2).

[0027]

(2) 99.9 / 0.1 ≦ (A) / (B) ≦ 80.0 / 20.0 (1) 99.5 / 0.5 ≦ {(A) + (B)} / (C) ≦ 70.0 / 30.0 (2) (However, In the formulas (1) and (2), (A) is a weight part of an alkoxysilane having an epoxy group, (B) is a weight part of an alkoxysilane having an amino group, and (C) is a weight of a cationic surfactant. Part.)

If the weight ratio ((A) / (B)) of the alkoxysilanes (A) and (B) is less than 99.9 / 0.1, a strong coating film will not be formed, On the other hand, if it is larger than 80.0 / 20.0, the pot life of the coating liquid may be shortened, and the productivity may be deteriorated.

The weight ratio of the alkoxysilanes (A) and (B) to the cationic surfactant (C) ({(A) + (B)} / (C)) is 99.5 / 0.5.
If the particle size is smaller than the above, the antistatic property is not exhibited, the handling property of the film is deteriorated, and further, the discharge due to the charging occurs during the silicone coating, which may cause a fire or explosion of the solvent. If it is larger than 0.0, the silicone may not be easily exposed to silicone.

Further, the alkoxysilanes (A) and (B) preferably have water solubility or water dispersibility.

The pH of the coating liquids of the alkoxysilanes (A) and (B), especially those aqueous coating liquids, may be adjusted to 4.0 to 7.0, and more preferably to 5.0 to 6.7. preferable. If the pH is less than 4.0 and more than 7.0, the coating solution becomes unstable and precipitation may occur.

As the acid for adjusting the pH of the coating solution, an inorganic acid such as hydrochloric acid, nitric acid or sulfuric acid, or an organic acid such as oxalic acid, formic acid, citric acid or acetic acid is used, and an organic acid is particularly preferable.

In the coating liquid, particularly the aqueous coating liquid, a surfactant such as a cationic surfactant and a nonionic surfactant is required in addition to the surfactant added as the above-mentioned cationic surfactant (C). It can be used by adding an amount. As such a surfactant, the surface tension of the coating liquid is set to 50 dyne / cm.
Or less, preferably 40 dyne / cm or less,
Those which promote wetting to a polyester film are preferable, for example, polyethylene oxide-polypropylene oxide block copolymer, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene monoalkylate, polyoxyethylene fatty acid ester, sorbitan Preferred examples include fatty acid esters and glycerin fatty acid esters.

Further, other additives such as an ultraviolet absorber, a pigment, an inorganic filler, an organic filler, a lubricant, an anti-blocking agent and the like can be mixed with the coating liquid within a range not to lose the effects of the present invention. .

The coating liquid is applied to at least one side of the polyester film before the completion of the crystal orientation, and then dried and thermally crosslinked to provide a crosslinked primer layer.

Here, as the polyester film before the completion of the crystal orientation, an unstretched film which is obtained by melting the polyester by heating and an unstretched film is formed in the longitudinal direction (longitudinal direction) or the transverse direction (width direction). Uniaxially stretched film stretched in any one of the above, further biaxially stretched film stretched in two directions of the longitudinal and transverse directions at low magnification (finally stretched again in the longitudinal or transverse direction to achieve orientation crystallization Biaxially stretched film before completion).

The solid content in the coating solution is preferably 30% by weight or less, particularly preferably 10% by weight or less. The coating amount of the coating liquid is 0.5 to ² per m ² of the running film.
0 g, especially 1 to 10 g, is preferred.

As a method for applying the coating liquid to the polyester film, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a microgravure coating method, a reverse coating method, a roll brush method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like may be applied alone or in combination. The aqueous coating liquid may contain a small amount of an organic solvent for the purpose of assisting the stability or coating property of the coating liquid.

The coating liquid applied to the polyester film is dried and thermally crosslinked. For example, in the case of a vertically uniaxially stretched polyester film coated with an aqueous coating liquid, the coating liquid is dried and thermally cross-linked while the polyester film is guided to a stenter, heated and then horizontally stretched and heat-set.

The orientation and crystallization conditions 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 has excellent adhesiveness to a polyester film and excellent adhesiveness to silicone. Therefore, when the silicone easy-adhesive film of the present invention is used and, for example, a silicone release layer is provided on the crosslinked primer layer, a release film having excellent durability can be obtained.

The silicone release layer is formed by an addition reaction between 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 using a platinum compound as a catalyst. Cured organopolysiloxane having a hydroxyl group bonded to a silicon atom and organosilane having a hydrolyzable functional group (for example, alkoxy group, oxime group, acetoxy group, etc.) Preferable examples include a cured film formed by a condensation reaction using a titanium compound as a catalyst.

Such a cured film is formed by applying a coating solution containing a component for forming the film on the primer layer and curing on the primer layer. Components for forming a film are dissolved in a solvent such as toluene, ethyl acetate, n-hexane, methyl ethyl ketone, or cyclohexanone to prepare a coating solution. The coating solution contains an organic platinum compound such as an organic platinum compound for accelerating a polymerization reaction. It is preferred to add a small amount of catalyst. As a method of applying the coating liquid, for example, a gravure coating method, a microgravure coating method, a reverse coating method, a spray coating method, a bar coating method, or the like can be 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, the silicone is often transferred to the pressure-sensitive adhesive due to insufficient polymerization, which is not preferable.

The release layer thus obtained is excellent in adhesion to the polyester film via the primer layer, has little transfer of the release layer component to the adhesive or the like, and has excellent durability.

The easily adhesive silicone film of the present invention is not restricted by the properties of the silicone provided on the crosslinked primer layer, but can be used in various applications depending on the properties of the silicone.

[0047]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. In addition, each characteristic value of the film was measured and evaluated by the following methods.

(1) Antistatic Property (a) Surface Specific Resistance The surface specific resistance of the crosslinked primer layer surface was measured using a specific resistance measuring device manufactured by Takeda Riken Co., at a measurement temperature of 23 ° C. and a measurement humidity of 60%. The surface specific resistance (Ω / □) after one minute at an applied voltage of 500 V is measured. The surface resistivity is 10 ¹³
It is preferably Ω / □ or less.

(B) Friction Charging The surface of the crosslinked primer layer was rubbed against a metal roll at a constant speed and a constant length, and the charge amount was measured with an electrostatic potential meter manufactured by Shisido Electrostatic Co., Ltd. The charge amount is preferably 3 kV or less in absolute value.

(2) Silicone Easy Adhesion A curable silicone resin (KS-772, 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 cure. A solution having a solid content of 5% was prepared by dissolving in toluene, and this solution was applied on the crosslinked primer layer at a coating amount of 1 g / m ² , followed by drying and curing at 150 ° C. for 1 minute, followed by separation. A shaped film was obtained and its easy adhesion was evaluated.

(A) Initial Easy Adhesion The surface of the release layer of the release film immediately after the release layer was applied (immediately after application and drying) was rubbed several times with a fingertip, and the release layer was observed to come off and adhere. The initial easy adhesion was evaluated according to the evaluation criteria described above.

(B) Durability and Easy Adhesiveness After the release film was kept in an atmosphere of 60 ° C. × 80% RH for one week, the surface of the release layer was rubbed several times with a fingertip to check whether the release layer fell off or adhered. Observation was made to evaluate the durable adhesion according to the following evaluation criteria. [Evaluation Criteria] ：: No change in the release layer is observed at all ………… Good adhesion property ○: Whitening due to peeling of the release layer is slightly observed ……… Easy adhesion is slightly good △: Whitening due to peeling of the release layer is observed in almost all areas. Slightly poor adhesion. ×: The release layer is completely peeled and lost.

(C) Backside non-transferability (residual adhesion rate) A polyester adhesive tape (Nitto 31B) was JIS
Cold rolled stainless steel plate (SUS3
04) was measured for the peeling force after application, and the result was taken as the basic adhesive force (f ₀ ). Next, the above-mentioned new polyester pressure-sensitive adhesive tape is pressure-bonded with a pressure roller of 2 kg on the release layer coating surface of the release film, and after maintaining for 30 seconds, the pressure-sensitive adhesive tape is peeled off. Then, the peeled adhesive tape was attached to the above stainless steel plate, and the peeling force was measured to obtain a residual adhesive force (f). From the obtained basic adhesive strength (f ₀ ) and residual adhesive strength (f), a residual adhesive rate was determined using the following equation.

[0054]

## EQU3 ## Residual adhesion rate (%) = (f / f ₀ ) × 100

The residual adhesion ratio is preferably 85% or more. If the residual adhesion ratio is less than 85%, for example, when the film is stored in a roll shape, it is undesirably transferred to the adjacent film surface, and the releasing property may be deteriorated.

[Examples 1 to 4 and Comparative Examples 1 to 3] 35
The intrinsic viscosity measured in o-chlorophenol at 0 ° C. is 0.
60 polyethylene terephthalate (average particle size 0.1μ)
m silica particles are contained in an extruder, and a film-like molten polymer is discharged from a die at about 20 ° C.
The molten polymer in the form of a film was rapidly cooled while being in close contact with the cooling drum by an electrostatic adhesion method to obtain an unstretched film. Next, the unstretched film was stretched 3.6 times in the machine direction at 140 ° C. to obtain a uniaxially stretched film. One side of the uniaxially stretched film contains the alkoxysilane, the antistatic agent and the surfactant (polyoxyethylene nonyl phenyl ether) shown in Table 1, and has a solid content of 2 wt. % Aqueous coating liquid was applied by a kiss coat method. Subsequently, the film was stretched 3.8 times in the transverse direction at 105 ° C., and heat-set at 210 ° C. to obtain a biaxially stretched polyethylene terephthalate film having a crosslinked primer layer having a thickness of 50 μm. Table 2 shows the properties of this film.

In Comparative Example 1, since the prepared aqueous coating solution had low stability and caused precipitation, application to a polyester film was not possible.

[0058]

[Table 1]

[0059]

[Table 2]

As is clear from Table 2, the silicone adhesive polyester film of the present invention has an antistatic property,
Excellent adhesion to silicone release layer.

[0061]

The silicone adhesive polyester film of the present invention has excellent antistatic properties and excellent adhesiveness to silicone.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08J 7/04 CFD C08J 7/04 CFDE // B05D 7/04 B05D 7/04 7/24 302 7/24 302Y

Claims (4)

[Claims] 1. A coating comprising an alkoxysilane having an epoxy group (A), an alkoxysilane having an amino group (B) and a cationic surfactant (C) on at least one surface of a polyester film before completion of crystal orientation. A silicone easy-adhesive polyester film provided with a crosslinked primer layer obtained by applying a liquid, drying, stretching and heat treatment. 2. The weight ratio of the alkoxysilane (A) having an epoxy group, the alkoxysilane (B) having an amino group, and the cationic surfactant (C) in the coating liquid is represented by the following formulas (1) and (2). The polyester film according to claim 1, which satisfies (1). 99.9 / 0.1 ≦ (A) / (B) ≦ 80.0 / 20.0 (1) 99.5 / 0.5 ≦ {(A) + (B)} / (C) ≦ 70.0 / 30.0 (2) (However, In the formulas (1) and (2), (A) is a weight part of an alkoxysilane having an epoxy group, (B) is a weight part of an alkoxysilane having an amino group, and (C) is a weight of a cationic surfactant. Part.) 3. The polyester film according to claim 1, wherein the cationic surfactant (C) is a quaternary ammonium salt having the following structure. Embedded image (Here, R ₁ , R ₂ , R ₃ and R ₄ each have 1 carbon atom.
To 30 alkyl groups, polyoxyethylene groups, hydroxyl-containing alkyl groups or benzyl groups, which may be different or the same.
X ^- (counter ion) represents an ethosulfate ion or nitrate ion. ) 4. The polyester film according to claim 1, wherein the polyester film is a film formed of polyethylene terephthalate or polyethylene-2,6-naphthalate.