JP2000141568A - Release film - Google Patents

Abstract

(57) [Summary] PROBLEM TO BE SOLVED: To provide an oligomer suitable for various release films.
-Transparency with minimal precipitation and silicone migration
Provide a good release film. SOLUTION: A polyester layer constituting both outer layers is
Compared to the raw material polyester in the polyester layer adjacent to the outer layer
Low oligomer content and high glass transition point
Derived from polyester raw material, surface oligomer precipitation
Output 8mg / m ^TwoOn one side of the laminated film below,
It has a release layer with a residual adhesion rate of 80% or more.
Release film characterized by simultaneously satisfying the following conditions. [Expression 1] ΔH ≦ 3 L ≧ 70 ……… (In the above formula, ΔH is the mold release after heat treatment at 170 ° C. for 30 minutes.
Difference (%) between turbidity of film and turbidity before heat treatment, L
Light transmittance (%) at 550 nm wavelength of mold film
Represents)

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 example, a liquid crystal display (hereinafter referred to as LC).
D) (which may be abbreviated as D) for protecting a liquid crystal polarizing plate, for producing a green sheet, and the like.

[0002]

2. Description of the Related Art Conventionally, release films based on polyethylene terephthalate film (hereinafter sometimes abbreviated as PET film) have been used for various purposes such as protection of liquid crystal polarizing plates and production of green sheets. I have. As a problem in the use of the release film, for example, there is a problem that oligomers precipitated on the surface of the release layer or on a surface where the release layer is not provided at high temperatures cause various problems in the production process.

[0003] For example, in a process of manufacturing a release film for protecting a liquid crystal polarizing plate, which is an example of non-adhesive use, a process in which a release film and a polarizing plate are laminated via an adhesive layer and wound into a roll. It is considered that oligomers are precipitated through a drying step after application of the pressure-sensitive adhesive. The oligomer deposited on the surface of the release layer is transferred to the surface of the other adhesive layer to which the adhesive is attached, and is obtained when an LCD is manufactured by attaching a polarizing substrate with an adhesive layer to which the oligomer is attached to a glass substrate. Problems such as a decrease in the brightness of the LCD may occur. In recent years, there has been a tendency to increase the brightness of the display screen for the purpose of improving the visibility of LCDs, and the above problem has become a serious problem.

On the other hand, as an example of the non-adhesive application, there is, for example, a green sheet manufacturing application. In a manufacturing process of a release film for manufacturing a green sheet, a ceramic slurry is applied to the surface of a release layer, and then a drying process is performed. Is considered to consist of a step of being wound up in a roll shape in a state of being laminated on a release film, and the oligomer is deposited through a drying step after slurry application. Oligomer deposited on the release layer surface is transferred to the surface of the green sheet in contact with the release surface, and using the green sheet to which the oligomer is attached, for example, when manufacturing a ceramic multilayer capacitor, when stacking green sheets together, In some cases, problems such as a decrease in the adhesive strength may occur.

[0005] Further, the oligomer which precipitates on the surface on which the release layer is not provided is transferred to the roll surface of the transporting roll, and if further processing is continued, the oligomer is deposited on the roll surface, and roll contamination is generated. . In recent years, with the aim of reducing manufacturing costs due to improvement in productivity, with the speeding up of the manufacturing process, there is a tendency to set the drying temperature especially higher in the drying process, and the above-mentioned oligomers are more likely to precipitate. It has become.

In addition, when the release layer of the release film transfers a large amount of silicone, the same problem as that of the oligomer described above may occur. Further, the release film may be required to have transparency in use, and an example thereof is an inspection step at the time of manufacturing a liquid crystal polarizing plate. In the inspection process, measures to prevent outflow of defective products by visual observation or use of a magnifying glass are taken at present,
If the transparency of the release film is insufficient, it is easy to overlook foreign substances and the like mixed in the product, and thus there is a problem that the outflow rate of defective products increases.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and its object is to solve the above problems. An object of the present invention is to provide a release film having an extremely small amount of oligomer precipitation and silicone migration, and having good transparency.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in view of the above problems, and as a result, have found that a release film having a specific structure can easily solve the above problems, and have completed the present invention. I came to. That is, the gist of the present invention is that the polyester layers constituting both outer layers are derived from a polyester raw material having a lower oligomer content and a higher glass transition point than the raw polyester of the polyester layer adjacent to both outer layers, and A release film having a release layer having a residual adhesion rate of 80% or more on one surface of a laminated film mainly having three or more layers having an oligomer precipitation amount of 8 mg / m ² or less. At the same time, there is a release film characterized by being satisfied.

[0009]

ΔH ≦ 3 L ≧ 70 (where ΔH is the turbidity of the release film after heat treatment at 170 ° C. for 30 minutes and the turbidity of the release film at room temperature before heat treatment) (L represents the light transmittance (%) at a wavelength of 550 nm of the release film.)

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The laminated polyester film constituting the release film of the present invention is obtained, for example, by stretching and heat-treating what is extruded by a so-called co-extrusion method in which the resin constituting each layer is co-melt extruded from an extruder. Can be Hereinafter, a coextruded three-layer film will be described as a laminated polyester film, but the present invention is not limited to a coextruded three-layer film.

In the present invention, the polyester used for the laminated polyester film may be a homopolyester or a copolyester. When the polyester is a homopolyester, the polyester is obtained by polycondensing an aromatic dicarboxylic acid and an aliphatic glycol. Examples of the aromatic dicarboxylic acid include terephthalic acid and 2,6-naphthalenedicarboxylic acid, and the aliphatic glycol includes ethylene glycol,
Examples include diethylene glycol and 1,4-cyclohexanedimethanol. Typical polyesters include polyethylene terephthalate (PET) and polyethylene-2,6-naphthalenedicarboxylate (PE
N) and the like.

On the other hand, the copolymer polyester which can be used in the present invention is a copolymer containing 30 mol% or less of the third component. As the dicarboxylic acid component of such a copolymerized polyester, isophthalic acid, terephthalic acid phthalate, 2,2
6-naphthalenedicarboxylic acid, adipic acid sebacic acid,
And one or more of oxycarboxylic acids (for example, P-oxybenzoic acid and the like), and as a glycol component, ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,4
-One or more of cyclohexanedimethanol, neopentyl glycol and the like.

In the present invention, the lamination ratio in the thickness direction of the laminated polyester film (the total thickness of both outer layers / the total thickness of the laminated polyester film) is usually 0.05 or more, preferably 0.1 or more. If the constituent ratio is less than 0.1, the effect of preventing oligomer precipitation may be insufficient. Further, the thickness of the outer layer is preferably 0.1 μm or more, more preferably 1 μm or more. When the outer layer thickness is less than 0.1 μm, the effect of preventing oligomer precipitation is insufficient, or when the outer layer contains particles. In some cases, particles may fall off. The upper limit of the lamination composition ratio is preferably 0.8 in consideration of the effect of preventing oligomer precipitation.

In the laminated polyester film constituting the release film in the present invention, it is necessary that the oligomer content of the polyester material constituting both outer layers is smaller than the oligomer content of the raw material polyester of the inner layer adjacent to both outer layers. is there. Specifically, the difference between the oligomer contents of the polyester raw materials constituting the inner layer and both outer layers is 0.1%.
It is preferably at least 3% by weight, more preferably at least 0.5% by weight.

The content of the oligomer in the polyester material constituting both outer layers is preferably 1.2% by weight or less, more preferably 0.9% by weight or less. From such a point of view, the polyester raw material forming the outer layer to be formed into a film may be subjected to a thermal crystallization treatment in advance to reduce the content of oligomers and shorten the melting time during film formation. As one form of thermal crystallization, a prepolymer having an intrinsic viscosity of about 0.3 to 0.6 is heat-treated at 210 to 260 ° C. under reduced pressure or an inert gas flow to increase the degree of polymerization. A polymerization method can also be adopted.

In the present invention, the amount of oligomer precipitated from the surface of the laminated polyester film must be 8 mg / m ² or less at the same time as using the above-mentioned low oligomer material. If the amount exceeds 8 mg / m ² , various problems occur when used as a release film. On the other hand, regarding the glass transition point of the polyester layer,
The lower the glass transition point of the film is, the faster the oligomer is precipitated from the film. Therefore, for both outer layers of the laminated polyester film, it is necessary to use a raw material whose glass transition point is higher than the glass transition point of the raw material polyester of the inner layer. Further, the difference in glass transition point between the outer layer raw material polyester and the inner layer raw material polyester is 5 ° C. or more,
It is preferable that the temperature is not lower than ° C.

In the present invention, it is preferable to incorporate particles into the polyester layer mainly for imparting lubricity. The type of particles to be blended is not particularly limited as long as the particles can impart lubricity to the film, and specific examples include, for example, silica, calcium carbonate, magnesium carbonate, barium carbonate, and calcium sulfate. , Calcium phosphate, magnesium phosphate silicon oxide,
Examples include particles of kaolin, aluminum oxide, titanium oxide and the like. Further, heat-resistant organic particles as described in JP-B-59-5216 and JP-A-59-217755 may be used. Examples of other heat-resistant organic particles include a thermosetting urea resin, a thermosetting phenol resin, a thermosetting epoxy resin, and a benzoguanamine resin. Further, during the polyester production process, precipitated particles in which a part of a metal compound such as a catalyst is precipitated and finely dispersed can be used.

On the other hand, the shape of the particles to be used is not particularly limited, and any of spherical, massive, rod-like, flat, etc. may be used. There is no particular limitation on the hardness, specific gravity, color and the like. These series of particles may be used in combination of two or more as necessary. The average particle size of the particles used is usually 0.01 to 3 μm, preferably 0.1 to 0.3 μm.
The range is from 01 to 1 μm. When the average particle size is less than 0.01 μm, the particles are likely to aggregate, and the dispersibility may be insufficient.On the other hand, when the average particle size exceeds 3 μm, the surface roughness of the film becomes too coarse, Problems may occur when a release layer is applied in a subsequent step.

Further, the particle content in the polyester layer is as follows:
Usually, it is in the range of 0.1 to 5% by weight, preferably 0.1 to 3% by weight. If the particle content is less than 0.1% by weight, the lubricity may be insufficient, while if it exceeds 5% by weight, the transparency of the laminated polyester film may be insufficient. May be. The method for adding particles to the polyester layer is not particularly limited, and a conventionally known method can be employed. For example, the particles can be added at any stage of producing the polyester, but preferably at the stage of esterification or after the end of the transesterification reaction.

A method of blending a polyester slurry with a slurry of particles dispersed in ethylene glycol or water using a kneading extruder with a vent, or
The particles are added by a method of blending the dried particles with the polyester raw material using a kneading extruder. In addition, an antioxidant, a heat stabilizer, a lubricant, a dye, a pigment, and the like can be added to the laminated polyester film of the present invention, if necessary, in addition to the above particles.

The thickness of the laminated polyester film constituting the release film in the present invention is not particularly limited as long as it can be formed into a film, but is usually 4 to 250, preferably 9 to 125 μm, most preferably. Is in the range of 12 to 100 μm. Next, a production example of the laminated polyester film in the present invention will be specifically described, but is not limited to the following production example.

That is, the above-mentioned polyester raw materials are laminated using three extruders, three-layer multi-manifolds or feed blocks, and extruded as a molten sheet from a slit die. Next, the molten sheet extruded from the die is cooled and solidified by a cooling roll to obtain an unstretched laminated sheet. At this time, in order to improve the flatness of the sheet, it is preferable to increase the adhesion between the sheet and the rotary cooling drum, and the electrostatic application adhesion method and / or the liquid application adhesion method are preferably employed.

Next, the obtained unstretched laminated sheet is preferably stretched at least in a uniaxial direction. The unstretched laminated sheet may be stretched in one direction by a roll or a tenter-type stretching machine. The stretching temperature is usually 130
To 170 ° C., and the stretching ratio is usually 2.5 to 7 times, preferably 3.0 to 6 times. Next, stretching is performed in a direction orthogonal to the stretching direction of the first stage. The stretching temperature is usually 13
0 to 170 ° C., and the stretching ratio is usually 3.0 to 7 times,
Preferably it is 3.5 to 6 times. And then, 1
Heat treatment is performed at a temperature of 80 to 270 ° C. under tension or relaxation within 30% to obtain a biaxially stretched laminated polyester film.

In the above stretching, the stretching in one direction is 2
It is also possible to use a method of performing the above steps. In that case,
It is preferable that the stretching is performed so that the stretching ratio in the two directions finally falls within the above range. It is also possible to simultaneously biaxially stretch the unstretched laminated sheet so that the area magnification is 10 to 40 times. Further, if necessary, the film may be stretched in the longitudinal and / or transverse directions again before or after the heat treatment.

A so-called coating and stretching method (in-line coating) for treating the surface of the film during the stretching step can be applied. Although it is not limited to the following, in particular, the coating treatment can be performed before the first-stage stretching is completed and before the second-stage stretching. When the coating layer is applied on the laminated polyester film by the coating and stretching method, the coating can be performed simultaneously with the stretching, and the thickness of the coating layer can be reduced according to the stretching ratio. Suitable films can be produced.

It is preferable that the release film of the present invention is provided with an antistatic property to prevent foreign substances such as dust and dirt from adhering to the surface of the release film. Examples of a method for imparting antistatic properties to the release film include a method of applying a coating layer containing an antistatic agent to the laminated polyester film, a method of blending the antistatic agent in the release layer, and a method of adding copper to the laminated polyester film. , A vapor deposition method of vapor-depositing a conductive material such as chromium, and a method of kneading an antistatic agent into a laminated polyester film. The surface resistivity of either side of the release film should be 10 ¹²
Ω or less, and among the above-mentioned methods, a method of applying a coating layer containing an antistatic agent to the laminated polyester film is preferable, and the coating layer is formed on the laminated polyester film by a coating stretching method (in-line coating method). Is preferably applied.

Examples of the antistatic agent to be incorporated in the above-mentioned coating layer include compounds such as quaternary ammonium salt-containing cationic compounds, phosphoric acid ester salts, and organic metal salts of sulfonates. By using a polymer containing either an ionized nitrogen element or a pyrrolidium ring in the main chain, the antistatic property is particularly good, which is preferable.

As an example of the polymer containing an ionized nitrogen element in the main chain, an ionene polymer can be given. As a specific example, Japanese Patent Publication No. 53-23377
JP, JP-B-54-10039, JP-A-47-1979
No. 34581, JP-A-56-76451, JP-A-58-93710, JP-A-61-18750.
And JP-A-63-68687.

Details of the ionene polymer can be found in ALAN
D. WILSON and HAVARD J. PROS
SER (Ed.) DEVELOPMENTS IN I
ONIC POLYMERS-2 ELSEVIER A
PPLIED SCIENCE PUBLISHER, 1
986), IONENE POLYMERS: PRO
It is also described in PERTIES AND APPLICATIONS.

On the other hand, the polymer containing a pyrrolidium ring in the main chain includes polymers having the following structures (A) and (B).

[0031]

Embedded image In the above formula, R ¹ and R ² are usually an alkyl group or a phenyl group, and R ¹ and R ² may be the same group, or may be an alkyl group or a phenyl group substituted by the following groups.

As an example of the substitutable functional group,
Hydroxy, amide, lower alkoxy, phenoxy, naphthoxy, cyano, thiophenoxy, cycloalkyl,
Triammonium lower alkyl and nitro groups can be substituted only on the alkyl group, and halogen groups can be substituted only on the phenyl group. Further, R ¹ and R ² may be chemically bonded, for example,-(CH ₂ ) n-, (n = integer of 2 to 5), -CH = CH-CH = CH-, -CH = CH-C
H = N -, - CH = CH-N = CH -, - (CH 2) 2
—O— (CH ₂ ) ₂ —, — (CH ₂ ) ₃ —O— (CH
₂ ) _3- and the like. Further, only ^one of R ¹ and R ² may be hydrogen.

[0033] X in the above formula ^{- is, Cl -, Br -, 1} /
2SO ₄ ²⁻ , 1 / 3PO ₄ ³⁻ inorganic acid residue, CH ₃ SO
₄ ⁻ , C ₂ H ₅ SO ₄ ⁻ , C _l H _{2l + 1} COO ⁻ (l = 1 to 6
Of an organic sulfonic acid residue or a carboxylic acid residue. The polymer of the above formula (A) can be obtained, for example, by subjecting a compound of the following formula (C) to cyclopolymerization in the presence of a radical polymerization catalyst.

[0034]

Embedded image The polymer of formula (B) can be obtained, for example, by subjecting the compound of formula (C) to cyclopolymerization in a system using sulfur dioxide as a solvent.

In the present invention, the polymer having a pyrrolidium ring in the main chain may have a compound of formula (C) and a compound having a polymerizable carbon-carbon unsaturated bond as a copolymerization component. The molecular weight of the polymer having a pyrrolidium ring in the main chain is preferably from 500 to 1,000,000, more preferably from 1,000 to 500,000. When the molecular weight is less than 500, although there is an antistatic effect, problems such as weak coating strength and easy blocking may occur.
If it is higher than 10,000, the viscosity of the coating solution may be high and the coating properties may be reduced.

In the present invention, it is preferable that the coating layer contains a binder polymer in addition to the antistatic agent in view of the durability of the coating layer. As a binder polymer,
Polyvinyl alcohol, polyacrylamide, polyalkylene glycol, polyalkyleneimine, methylcellulose, hydroxycellulose, starch, polyurethane, polyester, polyacrylate, chlorine-based polymer (polyvinyl chloride-vinyl chloride-vinyl acetate copolymer, etc.), polyolefin, etc. No. Among them, nonionic, cationic, and organic polymers that can be used as an aqueous solution or aqueous dispersion of an amphoteric system are preferable, and among them, when polyurethane, polyester, or polyacrylate is used, the adhesiveness to the overcoat layer is preferred. Is good. These polymers are provided with hydrophilicity by copolymerizing a nonionic, cationic or amphoteric hydrophilic component as one component of the monomer, and can be dispersed in water.

In the present invention, when the coating layer contains an antistatic agent and a binder polymer, the content of the antistatic agent is preferably in the range of 10 to 80% by weight. When the content of the antistatic agent is less than 10% by weight, the antistatic property may be insufficient. On the other hand, when the content exceeds 80% by weight,
Coating durability may be insufficient. In the present invention, a crosslinking agent may be used in combination as a coating agent, and specific examples thereof include methylolated or alkylolated urea-based, melamine-based, guanamine-based, acrylamide-based, polyamide-based compounds, epoxy compounds, aziridine compounds, Blocked polyisocyanates, silane coupling agents, titanium coupling agents, zircoaluminate coupling agents and the like can be mentioned. These cross-linking components may be previously bonded to the binder polymer.

The coating layer may contain inorganic particles for the purpose of improving the sticking property and sliding property of the coating layer, and specific examples thereof include silica, alumina, kaolin, calcium carbonate, titanium oxide, and barium salt. Can be Further, if necessary, an antifoaming agent, a coating improver, a thickener, an organic lubricant, an organic polymer particle, an antioxidant, an ultraviolet absorber, a foaming agent dye and the like may be contained.

In the present invention, when a coating layer is provided, the coating amount is 0.01 to 5 g / m ² , more preferably 0.02 to 5 g / m ² .
A range of 1 g / m ² is preferred. Coating amount is 0.01 g / m
If it is less than ² , the uniformity of the applied thickness may be insufficient, while if it exceeds 5 g / m ² , a problem may occur due to reduced slipperiness. In the present invention, as a method of applying a coating layer on the laminated polyester film, a coating method such as a bar coating method or a gravure coating method can be used in the same manner as in the case of applying a release layer described later.

The release layer constituting the release film in the present invention is not particularly limited as long as it contains a material having a release property. Above all, it is preferable to contain a curable silicone resin in that the releasability is improved. It may be a type containing a curable silicone resin as a main component,
A modified silicone type by graft polymerization with an organic resin such as a urethane resin, an epoxy resin, or an alkyd resin may be used.

As the type of the curable silicone resin, any of a curing reaction type such as an addition type, a condensation type, an ultraviolet curable type, an electron beam curable type, and a solventless type can be used. Specific examples include KS-774, K, manufactured by Shin-Etsu Chemical Co., Ltd.
S-775, KS-778, KS-779H, KS-8
56, X-62-2422, X-62-2461, DKQ3-202, DK manufactured by Dow Corning Asia Ltd.
Q3-203, DKQ3-204, DKQ3-205,
DKQ3-210, YSR-3 manufactured by Toshiba Silicone Co., Ltd.
022, TPR-6700, TPR-6720, TPR
-6721, SD72 manufactured by Dow Corning Toray Co., Ltd.
20, SD7226, SD7229 and the like. Further, a release control agent may be used in combination to adjust the release property of the release layer.

In the present invention, a coating method such as reverse roll coating, gravure coating, bar coating, doctor blade coating, or the like can be used as a method of further applying a release layer to the laminated polyester film. The coating amount of the release layer is preferably 0.01 to 5 g / m ² from the viewpoint of coatability. If the coating amount is less than 0.01 g / m ² , stability may be lacked from the viewpoint of coatability, and it may be difficult to obtain a uniform coating film. On the other hand, when the thickness is more than 5 g / m ² , the adhesion of the release layer itself, the curability and the like may be reduced.

The release film of the present invention comprises an oligomer precipitation preventing layer between the laminated polyester film and the release layer.
An antistatic layer, an intermediate layer such as an adhesive layer may be provided,
The laminated polyester film may be subjected to a surface treatment such as a corona treatment and a plasma treatment. The difference in turbidity (ΔH (%)) before and after heat treatment of the release film of the present invention must satisfy the following expression.

[0044]

ΔH ≦ 3 (ΔH ≦ 3) ΔH is obtained by subtracting the turbidity (%) of the release film at room temperature before the heat treatment from the turbidity (%) of the release film after the heat treatment at 170 ° C. for 30 minutes. Means difference. ΔH is 3
%, The amount of oligomers precipitated on the surface of the release layer of the release film or on the surface on which the release layer is not provided increases. For example, when used for protecting a liquid crystal polarizing plate, the transparency of the pressure-sensitive adhesive is increased. Inconveniences such as reduced adhesiveness or reduced adhesive strength of the pressure-sensitive adhesive layer occur. On the other hand, in the case of manufacturing a green sheet, for example, when a ceramic laminated capacitor is manufactured using a molded green sheet, problems such as a decrease in the inter-sheet adhesive force when the green sheets are stacked arise. Further, when the oligomer is deposited on the surface where the release layer is not provided, the oligomer is transferred to the roll surface of the transporting roll, and when the processing is further continued, the oligomer is deposited on the roll surface, and the roll is contaminated. become. ΔH is preferably 2% or less,
More preferably, it is 1% or less.

In the release film of the present invention, the light transmittance (L) at a wavelength of 550 nm needs to satisfy the following expression.

[0046]

L ≧ 70 When L is less than 70%, the transparency of the release film is insufficient. For example, when the film is used for protecting a liquid crystal polarizing plate, it may be used in an inspection process at the time of manufacturing the polarizing plate. The outflow rate of defective products will increase, and it will be difficult to cope with the same application requiring transparency in addition to low oligomerity. The L value is preferably 80% or more, more preferably 85% or more.

Further, the residual adhesive ratio of the release layer constituting the release film in the present invention is such that the transfer or transfer of silicone to the surface of the pressure-sensitive adhesive layer to be bonded or the surface of the transport roll in the manufacturing process is suppressed. At 80%
Or more, preferably 90% or more,
Most preferably, it is 95% or more. 80% residual adhesion
If it is less than 5, the silicone transfer component is transferred to the roll surface of the transport roll in the production process, and the adhesive force of the pressure-sensitive adhesive layer in contact with the release surface is reduced. On the other hand, in the case of manufacturing a green sheet, for example, when a ceramic laminated capacitor is manufactured using a molded green sheet, problems such as a decrease in the inter-sheet adhesive force when the green sheets are stacked arise.

The release film of the present invention has a surface specific resistance (R) of any one side of 10 ¹² Ω or less, and more preferably 10 10 Ω or less.
It is preferable that the resistance is ⁹ Ω or less from the viewpoint of preventing foreign substances such as dust and dirt from adhering to the release film. If the R value exceeds 10 ¹² Ω, the antistatic effect of the release film tends to be insufficient, and foreign matter such as dust and dirt may adhere to the surface of the release film. For example, in the liquid crystal polarizing plate manufacturing process, when the foreign matter is further mixed into the product, if it adheres to the surface of the pressure-sensitive adhesive layer, problems such as a decrease in the brightness of the obtained LCD will occur. On the other hand, when foreign matter adheres to the surface of the release layer in the production of a green sheet, problems such as repelling the slurry at the time of applying the ceramic slurry or generating pinholes may occur.

[0049]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the examples and comparative examples, “parts” means “parts by weight”. The measuring method used in the present invention is as follows. (1) Measurement of Intrinsic Viscosity of Polyester 1 g of polyester from which other polymer components and pigments incompatible with polyester were removed was precisely weighed, and phenol / tetrachloroethane = 50/50 (weight ratio) mixed solvent 10
0 ml was added and dissolved, and the measurement was performed at 30 ° C. (2) Measurement of average particle size (d ₅₀ : μm) 50% of integrated (weight basis) in equivalent spherical distribution measured using a centrifugal sedimentation type particle size distribution measuring device (SA-CP3 manufactured by Shimadzu Corporation). Was taken as the average particle size. (3) Measurement of glass transition point (Tg) of polyester 10 mg of a sample freeze-dried in advance is set in a DSC device (“DSC2920” manufactured by TA Instruments) and heated to 200 ° C. at a rate of 10 ° C./min. After warming, it is quenched with liquid nitrogen and again at a rate of 10 ° C./min.
The temperature was raised in the range of 200 ° C., and the glass transition point (Tg) was measured. (4) Measurement of Polyester Oligomer Content 5 g of a polyester chip was precisely evaluated, extracted with chloroform using a Soxhlet extractor for 24 hours, and the weight of the obtained oligomer with respect to the original polyester chip was calculated. (5) Measurement of the amount of oligomer precipitated on the surface of the laminated polyester film A sample sample was cut into 4 cm squares, and chloroform 20
cm ³ was immersed in an Erlenmeyer flask at 30 ° C. for 20 minutes. Thereafter, the sample was removed, the ultraviolet absorption spectrum of the treatment solution was measured, and the absorbance at a wavelength of 246 nm was measured. The amount of oligomer extracted from the sample sample was determined from the relationship between the absorbance and the amount of oligomer. Note that a calibration curve for the relationship between the absorbance and the amount of oligomer is prepared in advance. (6) Difference in turbidity before and after heat treatment of the release film (Δ
H) Evaluation A sample film was prepared using a hot air circulation furnace manufactured by Tabai Seisakusho.
Free end heat treatment was performed at 70 ° C. for 30 minutes. After that, JI
According to SK-7105, the turbidity of the release film before and after heat treatment was measured using an integrating sphere turbidity meter “NDH-20D” manufactured by Nippon Denshoku Industries Co., Ltd. The difference (ΔH) was calculated. (7) Evaluation of Residual Adhesion Rate of Release Film Residual Adhesion: Nitto Denko (manufactured) No. 2 was applied to the silicone surface of the sample film. 31B adhesive tape was reciprocated with a 2 kg rubber roller for one reciprocation, heat-treated at 100 ° C. for 1 hour, and then the sample film was peeled off from the pressed sample. 31
The adhesive force of the pressure-sensitive adhesive tape B was measured according to the method of JIS-C-2107 (adhesive force to a stainless steel plate, 180 ° peeling method), and this was defined as residual adhesive force.

Basic adhesive strength: A sample film was pressure-bonded to a stainless steel plate in accordance with JIS-C-2107 using the same tape (No. 31B) as in the case of the residual adhesive strength, and measured in the same manner. The value at this time was defined as the basic adhesive strength. Using these measured values, the residual adhesion rate was determined by the following equation.

[0051]

(Equation 5) The measurement was performed at 20 ± 2 ° C. and 65 ± 5% RH. (8) Evaluation of Light Transmittance (L) at 550 nm Wavelength of Release Film Double Beam Spectrophotometer (Model 228, manufactured by Hitachi, Ltd.)
And a wavelength of 350 using a tungsten lamp light source.
The light transmittance was continuously measured in the region of ８００800 nm, and the light transmittance at a wavelength of 550 nm was read from the recording chart. (9) Evaluation of Release Force (F) of Release Film A double-sided adhesive tape (Nitto Denko “N
o. 502 "), 50 mm x 30
Cut to 0 mm. Thereafter, the peeling force after leaving at room temperature for 1 hour is measured. The peeling force was measured using a tensile tester (“Intesco Model 2001” manufactured by Intesco Corporation).
180 ° peeling was performed under a tensile speed of 300 mm / min. (10) Evaluation of antistatic property (R) of release film 50 m of internal electrode manufactured by Yokogawa Hewlett-Packard Company
1600 which is a concentric electrode having a diameter of 70 mm and an external electrode having a diameter of 70 mm
8A (trade name) was set at 23 ° C. under a 50% RH atmosphere, a voltage of 100 V was applied, and the surface resistivity was measured with the company's high resistance meter 4329A (trade name). Was determined. << Judgment Criteria >> ：: 10 ⁹ Ω or less Δ: More than 10 ⁹ Ω and 10 ¹² Ω or less ×: More than 10 ¹² Ω Δ or more is a level that does not pose any practical problem.

Production Example 1 (Polyethylene terephthalate A)
1) 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate were placed in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction. In short, the temperature was raised to 230 ° C. to substantially end the transesterification reaction. Then, ethylene glycol slurry, 0.04 part of ethyl acid phosphate, 0.01 part of germanium oxide, and silica particles having an average particle diameter of 0.25 μm were added to 0.1 part.
After adding 3 parts, the temperature was increased to 280 ° C. and the pressure was increased to 1 in 100 minutes.
The pressure reached 5 mmHg, and the pressure was gradually reduced thereafter to finally reach 0.3 mmHg. After 4 hours, the inside of the system was returned to normal pressure to obtain polyethylene terephthalate having an intrinsic viscosity of 0.61. Furthermore, solid-state polymerization was performed at 0.03 mmHg and 220 ° C. for 7 hours to obtain polyethylene terephthalate A1 having an intrinsic viscosity of 0.68, a glass transition point of 68 ° C., and an oligomer content of 0.68% by weight.

Production Example 2 (Polyethylene terephthalate B)
1) The polyethylene terephthalate A1 obtained in Production Example 1 was produced in the same manner as in Production Example 1 except that solid phase polymerization was not performed, and the intrinsic viscosity was 0.61 and the glass transition point was 68.
Polyethylene terephthalate B1 having an oligomer content of 1.25% by weight at ℃ was obtained.

Production Example 3 (Polyethylene terephthalate A)
2) In the same manner as in Production Example 1 except that 0.2 parts of titanium dioxide particles having an average particle diameter of 0.27 μm were added instead of adding 0.3 parts of silica particles having an average particle diameter of 0.25 μm. Thus, polyethylene terephthalate A2 having an intrinsic viscosity of 0.68, a glass transition point of 68 ° C., and an oligomer content of 0.68% by weight was obtained.

Production Example 4 (Polyethylene-2,6-naphthalate A3) 100 parts of dimethyl 2,6-naphthalenedicarboxylate, 60 parts of ethylene glycol, magnesium acetate tetrahydrate 0.1 part
09 parts were placed in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction. Then, after adding 0.3 parts of silica particles having an average particle diameter of 0.25 μm, 0.03 parts of phosphoric acid and 0.04 parts of antimony trioxide were added, and a polycondensation reaction was carried out by a conventional method to obtain an intrinsic viscosity of 0.60 Glass transition point 112 ° C, oligomer content 0.24% by weight
Of polyethylene-2,6-naphthalate.

Production Example 5 (Polyethylene-2,6-naphthalate A4) In Production Example 4, titanium dioxide particles having an average particle size of 0.27 μm were used instead of adding 0.3 parts of silica particles having an average particle size of 0.25 μm. Except for adding 0.2 part, in the same manner as in Production Example 4, intrinsic viscosity 0.60, glass transition point 112 ° C,
Polyethylene having an oligomer content of 0.24% by weight
2,6-Naphthalate A4 was obtained.

Production Example 6 (Laminated polyester film F
1) The polyethylene terephthalates A1 and B1 produced in Production Example 1 and Production Example 2 were dried at 180 ° C. for 4 hours in an inert gas atmosphere, melted at 290 ° C. by separate melt extruders, extruded from a die, and discharged. It was cooled and solidified on a cooling roll whose surface temperature was set to 40 ° C. by using an applied adhesion method to obtain an unstretched laminated sheet. The obtained laminated sheet was stretched 3.3 times in the longitudinal direction at 130 ° C. Next, after applying a coating agent having the following composition, the film was guided to a tenter and stretched 3.3 times in the transverse direction at 130 ° C., and then heat-fixed at 230 ° C., and the thickness of the dried coating layer was 0.1 mm. 38 μm-thick laminated polyester film F coated with a 05 μm coating layer
1 was obtained. The layer structure of the obtained film is A1 / B1 / A
1 = 9/20/9 (μm)

[0058]

[Table 1] << Coating composition >> ────────────────────────────────── Nitrogen element ionized in the main chain A 70% by weight of a binder containing Nippon Carbide Co., Ltd. Nicazole FX-625 which is a polyacrylate cationic water dispersion 30% by weight ────────────────

[0059]

Embedded image << Structure of Polymer A >> Average molecular weight ~ 6000 Production Example 7 (Laminated Polyester Film F2) A laminated polyester film F2 was obtained in the same manner as in Production Example 6, except that the coating composition in Production Example 6 was changed to the following coating composition. The layer structure of the obtained film is A1 / B
1 / A1 = 9/20/9 (μm)

[0060]

[Table 2] << Coating composition >> ─────────────────────────────────── Nitrogen ionized in the main chain Element-containing polymer B 70% by weight Binder (nonionic 30% by weight terpolymer of methyl methacrylate / ethyl acrylate / methylol acrylamide 30% by weight aqueous dispersion) monomer ratio: 47.5 / 47.5 / 5 mol% ──────────────────────────────────

[0061]

Embedded image << Structure of Polymer B >> Production Example 8 (Laminated Polyester Film F3) A laminated polyester film F3 was obtained in the same manner as in Production Example 6, except that the coating composition in Production Example 6 was changed to the following coating composition. The layer structure of the obtained film is A1 / B
1 / A1 = 9/20/9 (μm)

[0062]

[Table 3] << Coating agent composition >> ピ ロ Pyrrolidium ring in main chain Polymer contained (Daiichi Kogyo Seiyaku Co., Ltd .: Sharol DC-902P) 20% by weight Binder (acrylic resin) 60% by weight Crosslinking agent (methoxymelamine) 20% by weight製造 Production Example 9 (Laminated polyester film F4) Production Example 6 was repeated except that the coating composition in Production Example 6 was changed to the following coating composition. Similarly, a laminated polyester film F4 was obtained. The layer structure of the obtained film is A1 / B
1 / A1 = 9/20/9 (μm)

[0063]

[Table 4] << Coating composition >> Pyrrolidium ring in main chain Contained polymer (PAS-88, manufactured by Nitto Bo) 20% by weight Binder (acrylic resin) 60% by weight Crosslinking agent (methoxymelamine) 20% by weight ────────────────── Production Example 10 (PET film F5) Except that in Production Example 6, polyethylene terephthalate B1 was used instead of polyethylene terephthalate A1 and no coating layer was provided. Is produced in the same manner as in Production Example 6, and P
An ET film F5 was obtained.

Production Example 11 (Laminated polyester film F
6) In Production Example 6, except that no coating layer is applied.
To produce a laminated polyester film F6. The layer structure of the obtained film is A1 / B1 / A1 =
9/20/9 (μm). Production Example 12 (laminated polyester film F7) Same as Production Example 6, except that in Example 6, polyethylene terephthalate B1 was used instead of one polyethylene terephthalate A1, and a coating layer was applied on the other polyethylene terephthalate A1. Manufactured
A laminated polyester film F7 was obtained. The layer structure of the obtained film was A1 / B1 = 9/29 (μm).

Production Example 13 (Laminated polyester film F
8) In Production Example 6, a laminated polyester film F8 was obtained in the same manner as in Production Example 6, except that the coating composition was changed to the following coating composition. The layer structure of the obtained film is A1 / B
1 / A1 = 9/20/9 (μm)

[0066]

[Table 5] << Coating composition >> ──────────────────────────────────── Grade 4 in side chain Polyacrylate antistatic agent containing ammonium salt (Mitsubishi Chemical Corporation ST-1000) 40% by weight Crosslinking agent (methoxymethylmelamine) 60% by weight ─────────────────── Production Example 14 (laminated polyester film F9) In Production Example 6, the thickness was 90 Å as an oligomer precipitation preventing layer instead of applying a coating agent. A laminated polyester film F9 was obtained in the same manner as in Production Example 6 except that the copper vapor-deposited layer was laminated. The layer structure of the obtained film was A1 / B1 / A1 = 9/20/9 (μm).

Production Example 15 (Laminated polyester film F
10) A laminated polyester film F10 was obtained in the same manner as in Production Example 6, except that a copper vapor-deposited layer having a thickness of 40 Å was laminated as an oligomer precipitation preventing layer instead of applying a coating agent. The layer configuration of the obtained film was A1 / B1 / A1 = 3/32/3 (μm).

Production Example 16 (Laminated polyester film F
11) In Production Example 6, instead of applying a coating agent, an oligomer precipitation preventing layer made of γ-aminopropyltriethoxysilane was applied on one side such that the coating amount after drying was 0.1 g / m ^2. A laminated polyester film F11 was obtained in the same manner as in Production Example 6 except for performing the above. The layer structure of the obtained film was A1 / B1 / A1 = 9/20/9 (μm).

Production Example 17 (Laminated polyester film F
12) In Preparation Example 6, instead of applying a coating agent, an oligomer precipitation preventing layer composed of γ-aminopropyltriethoxysilane was applied on both sides such that the coating amount after drying was 0.1 g / m ^2. A laminated polyester film 12 was obtained in the same manner as in Production Example 6 except for performing the above. The layer structure of the obtained film was A1 / B1 / A1 = 9/20/9 (μm).

Production Example 18 (Laminated polyester film F
13) In Production Example 6, a laminated polyester film F13 was obtained in the same manner as in Production Example 6, except that polyethylene terephthalate A2 was used instead of polyethylene terephthalate A1. The layer structure of the obtained film is A2 /
B1 / A2 = 9/20/9 (μm)

Production Example 19 (Laminated polyester film F
14) In Production Example 6, a laminate polyester film F14 was obtained in the same manner as in Production Example 6, except that the film was not stretched in the longitudinal direction by a factor of 3.3. The layer structure of the obtained film is A1 /
B1 / A1 = 9/20/9 (μm) Production Example 20 (Laminated Polyester Film F15) A laminated polyester film F15 was obtained in the same manner as in Production Example 6, except that polyethylene-2,6-naphthalate A3 was used instead of polyethylene terephthalate A1. The layer structure of the obtained film was A3 / B1 / A3 = 9/20/9 (μm).

Production Example 21 (Laminated polyester film F
16) A laminated polyester film F16 was obtained in the same manner as in Production Example 6, except that polyethylene-2,6-naphthalate A4 was used instead of polyethylene terephthalate A1. The layer structure of the obtained film was A4 / B1 / A4 = 9/20/9 (μm).

Production Example 22 (Laminated polyester film F
17) In Production Example 6, a laminated polyester film F17 was obtained in the same manner as in Production Example 6, except that the thickness configuration of each polyester layer was different. The layer configuration of the obtained film was A1 / B1 / A1 = 3/32/3 (μm). Table 1 below shows the amount of surface oligomer extraction of the laminated polyester films obtained in Production Examples 6 to 22.

[0074]

[Table 6] Example 1 A release layer having the following composition was further applied to the surface of the laminated polyester film F1 obtained in Production Example 6, on which the application layer was applied, so that the application amount was 0.1 g / m ² (after drying). Set up
A release film was obtained. The properties of the obtained release film are shown in Table 2 below.

[0075]

[Table 7] << Composition of release agent >> 硬化 Curable silicone resin (KS- 847H: Shin-Etsu Chemical Co., Ltd. 100 parts Hardener (PL-50T: Shin-Etsu Chemical Co., Ltd.) 1 part MEK / toluene mixed solvent 1500 parts ────────────────────── ─────────── Example 2 The procedure of Example 1 was repeated, except that the laminated polyester film F2 was used instead of the laminated polyester film F1, to produce a release film. .

Example 3 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F3 was used instead of the laminated polyester film F1. Example 4 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F4 was used instead of the laminated polyester film F1.

Example 5 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F8 was used instead of the laminated polyester film F1. Example 6 A release film was obtained in the same manner as in Example 1, except that the laminated polyester PET film F10 was used instead of the laminated polyester film F1.

Example 7 A release film was obtained in the same manner as in Example 1 except that the release agent was changed to the one having the following composition.

[0079]

[Table 8] << Releasing agent composition >> 硬化 Curable silicone resin (KS -723A: Shin-Etsu Chemical Co., Ltd. 100 parts Curable silicone resin (KS-723B: Shin-Etsu Chemical Co., Ltd.) 25 parts Curing agent (PS-3: Shin-Etsu Chemical Co., Ltd.) 5 parts MEK / toluene mixed solvent 1500 parts ８ Example 8 Example 8 was the same as Example 1 except that a release agent having the following composition was used. A release film was obtained in the same manner.

[0080]

[Table 9] << Composition of release agent >> ───────────────────────────────── Curable silicone resin (X- 62-470: Shin-Etsu Chemical Co., Ltd. 100 parts Adhesion enhancer (X-92-470: Shin-Etsu Chemical Co., Ltd.) 2 parts Curing agent (PS-1: Shin-Etsu Chemical Co., Ltd.) 5 parts Antistatic agent (X-92-162: Shin-Etsu Co., Ltd.) 5 parts MEK / toluene mixed solvent 1500 parts ───────────────────────────────── Example 9 Example 1, a release film was obtained in the same manner as in Example 1, except that the laminated polyester film F11 was used instead of the laminated polyester film F1.

Example 10 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F12 was used instead of the laminated polyester film F1. Example 11 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F14 was used instead of the laminated polyester film F1.

Example 12 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F6 was used instead of the laminated polyester film F1. Example 13 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F15 was used instead of the laminated polyester film F1.

Example 14 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F17 was used instead of the laminated polyester film F1. Comparative Example 1 A release film was obtained in the same manner as in Example 1, except that a release agent having the following composition was used.

[0084]

[Table 10] << Composition of release agent >> 硬化 Curable silicone resin 100 Part (DKQ3-3061: Dow Corning Asia) Hardener (FSK-1638: Dow Corning Asia) 2 parts MEK / toluene mixed solvent 1500 parts比較 Comparative Example 2 The procedure of Example 1 was repeated, except that the laminated polyester film F5 was used instead of the laminated polyester film F1. A mold film was obtained.

Comparative Example 3 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F7 was used instead of the laminated polyester film F1. Comparative Example 4 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F9 was used instead of the laminated polyester film F1.

Comparative Example 5 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F13 was used instead of the laminated polyester film F1. Comparative Example 6 A release film was obtained in the same manner as in Example 1, except that the laminated polyester film F16 was used instead of the laminated polyester film F1.

The results obtained above are summarized in Table 2 below.

[0088]

[Table 11]

[0089]

[Table 12]

[0090]

The release film of the present invention is suitable for various types of release, such as, for example, for protecting a liquid crystal polarizing plate and for producing a green sheet. The release amount of the oligomer is as small as possible, the migration of silicone is small, and the transparency is low. Good and its industrial value is extremely high.

Continued on the front page (72) Inventor Shoji Inagaki 347 Inoguchi, Yamato-cho, Sakata-gun, Shiga Prefecture F-term (reference) 4F100 AK41A AK41B AK41C AK42 AK52D AK80D AS00D BA04 BA07 BA10A BA10 E46D CC00 EJ08 GB41 JA05A JA05B JB12D JG03D JG04D JL14D JN01D JN02 YY00D

Claims (5)

[Claims] The polyester layer constituting both outer layers is derived from a polyester raw material having a lower oligomer content and a higher glass transition point than the raw polyester of the polyester layer adjacent to both outer layers, and the surface oligomer precipitation amount Is a release film having a release adhesion layer having a residual adhesion rate of 80% or more on one surface of a laminated film having three or more layers, which is not more than 8 mg / m ^2. A release film characterized in that: ΔH ≦ 3 L ≧ 70 (ΔH is the turbidity of the release film after heat treatment at 170 ° C. for 30 minutes and the turbidity of the release film at room temperature before heat treatment. (L represents the light transmittance (%) at a wavelength of 550 nm of the release film.) 2. A method according to claim 1, wherein the surface resistivity of one of the surfaces is 10
The release film according to claim 1, wherein the release film has a resistance of ¹² Ω or less. 3. The release film according to claim 1, further comprising a coating layer containing an antistatic agent and a binder polymer on at least one surface. 4. The release film according to claim 3, wherein the antistatic agent is a polymer containing either an ionized nitrogen element or a pyrrolidium ring in the main chain. 5. The release film according to claim 1, wherein the release layer contains a curable silicone resin.