JPH05138667A - Mold-releasing polyester film - Google Patents

Abstract

PURPOSE:To provide a mold-releasing polyester film capable of performing a sufficient adhesive property and, besides, having an excellent separating property, and exhibiting no damage in the ink adhesiveness of a resin sheet after separation. CONSTITUTION:On at least one surface of a polyester film, a coat layer of polyester resin and/or polyurethane resin is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold releasing polyester film, and more particularly to a mold releasing polyester film used for casting various resins.

[0002]

2. Description of the Related Art Polyester films are widely used as release films because of their excellent toughness, smoothness, flatness and heat resistance. For example, casting an emulsion or solution of each resin such as urethane resin, acrylic resin, vinyl chloride resin (hereinafter abbreviated as “PVC”) on a release polyester film, and peeling from the release polyester film after heat treatment. There is known a method of obtaining a resin sheet.

In recent years, a mark sheet, which is obtained by cutting and sticking a colored PVC sheet obtained by blending various pigments with PVC, has been attracting attention. In the production of the above vinyl chloride mark sheet, in particular, a vinyl chloride mark sheet that has been subjected to adhesive processing, usually, vinyl chloride and additives such as pigments and plasticizers are uniformly dispersed in a solvent to prepare an emulsion or solution, and then the emulsion. Alternatively, the solution is cast on a releasing polyester film and then dried to form a vinyl chloride sheet, and then,
A method is employed in which an adhesive and release paper are sequentially laminated on the vinyl chloride sheet and then peeled from the release polyester film.

[0004]

However, when a normal polyester film is used as a release film, the releasability between the polyester film and the PVC sheet is poor, and the gloss of the release surface of the PVC sheet is lost. Value decreases. This tendency is remarkable when the peeling speed is increased, and sometimes the PVC sheet is broken.

In order to solve the above problems, a releasing polyester film coated with a silicone resin has been proposed. However, when a silicone resin-coated release polyester film is used, there is a problem that vinyl chloride is peeled off from the release polyester film in the step of laminating the adhesive. Further, since the silicone resin is transferred to the peeled surface of the vinyl chloride, the ink adhesiveness when printing on the vinyl chloride surface deteriorates.

In addition, the recursive reflection sheet is prepared by casting an acrylic resin solution containing glass beads on a releasing polyester film and drying it, and then vapor-depositing a metal on the resin layer. And a release paper are laminated, and then the polyester film for release is peeled off. However, also in the production of the recursive reflection sheet, when the conventionally known release polyester film is used, there are the same problems as in the production of the vinyl chloride sheet.

The present invention has been made in view of the above circumstances, and an object thereof is to exhibit sufficient adhesiveness, and
It is an object of the present invention to provide a releasing polyester film which is excellent in releasability and which does not impair the ink adhesion of the resin sheet after peeling.

[0008]

Means for Solving the Problems That is, the gist of the present invention is a polyester film for release, comprising a polyester film and / or a polyurethane resin coating layer on at least one surface of the polyester film. Exist.

The present invention will be described in detail below. In the releasing polyester film of the present invention, the polyester constituting the base film is a highly crystalline linear saturated polyester synthesized from an aromatic dibasic acid or its ester-forming derivative and a glycol component. Specific examples include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate. The above polyester may be a homopolymer or a copolymer obtained by copolymerizing another third component.

It is preferable to add fine particles to the above polyester by a particle addition method or a particle precipitation method in order to make the obtained film have a slip property. As the fine particles used in the particle addition method, organic or inorganic fine particles described below can be used. Also, large particles can be positively added to the above polyester in order to obtain a matte film. When the releasing polyethylene film is a matte film, the peeling surface of the vinyl chloride sheet has a uniformly roughened and matte surface.

In the release polyester film of the present invention, the polyester resin constituting the coat layer is, for example, JP-B-47-40873 or JP-A-50-.
83,497, JP-A-50-121336, JP-A-5
Known polyester resins disclosed in JP-A No. 2-155640 can be used.

Examples of the dicarboxylic acid component include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid. .. In practice, for the purpose of improving the dispersibility in a solvent containing water as a main medium, a dicarboxylic acid component having a sulfonate group, for example, sulfoterephthalic acid, sulfoisophthalic acid, sulfonaphthalene-2,6-dicarboxylic acid, etc. It is preferred to use the sulphonic acid salt of as a copolymerization component.

As the glycol component, aliphatic,
It may be any alicyclic or aromatic diol, and specific examples of such glycol component include ethylene glycol, 1,4-butanediol, diethylene glycol,
1,4-cyclohexane dimethanol, poly (oxyalkylene) glycol, etc. can be mentioned.

In the releasing polyester film of the present invention, examples of the polyurethane resin constituting the coat layer include, for example, JP-B-42-24194 and JP-B-46-
7720, Japanese Patent Publication No. 46-10193, Japanese Patent Publication No. 49-
37839, JP-A-50-123197, JP-A-5
Known polyurethane-based resins disclosed in JP-A-3-126058 and JP-A-54-138098, or polyurethane-based resins similar thereto can be used.

Examples of polyisocyanates include tolylene diisocyanate, phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate and isophorone diisocyanate. ..

As the polyol, polyoxyethylene glycol, polyoxypropylene glycol,
Examples thereof include polyether polyols such as polyoxytetramethylene glycol, polyethylene adipate, polyethylene-butylene adipate, polyester polyols such as polycaprolactone, acrylic polyols, castor oil and the like. Usually molecular weight 300-200
No polyol is used.

As the chain extender or crosslinking agent, ethylene glycol, propylene glycol, butanediol, diethylene glycol, trimethylolpropane, hydrazine, ethylenediamine, diethylenetriamine, 4,4'-diaminodiphenylmethane, 4,
4'-diaminodicyclohexylmethane, water, etc. can be mentioned.

The above-mentioned polyurethane-based resin is an anionic substituent such as --SO ₃ H group or --OSO ₃ H group for the purpose of improving the solubility in a solvent containing water as a main medium.
It is preferable to have a —COOH group and an ammonium salt, an alkali metal salt or an alkaline earth metal salt thereof. Examples of the method for producing such a polyurethane resin include the following production methods (1) to (3).

(1) Polyisocyanate, polyol,
A production method using a compound having an anionic substituent as a chain extender or the like. For example, a polyisocyanate having an anionic substituent can be obtained by a method of sulfonating an aromatic isocyanate compound. Further, an isocyanate compound having a sulfuric acid ester salt of amino alcohol or a diaminocarboxylic acid salt can also be used.

(2) A method of reacting a compound having an anionic substituent with an unreacted isocyanate group of the polyurethane produced. As the compound having an anionic substituent, examples of the anionic substituent include bisulfite, aminosulfonic acid and salts thereof, aminocarboxylic acid and salts thereof, sulfuric acid ester of aminoalcohols and salts thereof, hydroxyacetic acid. And compounds having salts thereof can be used.

(3) Active hydrogen-containing group (O
H, COOH, etc.) with a specific compound.
Specific compounds include, for example, dicarboxylic acid anhydrides,
Tetracarboxylic acid anhydride, sultone, lactone, epoxycarboxylic acid, epoxysulfonic acid, 2,4-dioxo-oxazolidine, isatoic acid anhydride, hoston and the like can be used. Further, a 3- to 7-membered cyclic compound showing a salt type group such as carbyl sulfate or a group capable of forming a salt after ring opening can also be used.

Inorganic or organic fine particles may be dispersed in the above polyester resin and / or polyurethane resin in order to impart slippage to the releasing polyester film.

Examples of the inorganic fine particles include silica,
Silica sol, alumina, alumina sol, zirconium sol, kaolin, talc, calcium carbonate, titanium oxide,
Examples thereof include barium salt, carbon black, molybdenum sulfide, antimony oxide sol, and so-called conductive metal fine particles. Examples of the organic fine particles include fine particles of fluorine resin, epoxy resin, benzoguanamine resin, and acrylic resin. In addition to the above,
It is also possible to use organic polymer particles having inorganic particles as the core. Such organic polymer fine particles can be obtained by polymerizing a polymer in the presence of inorganic fine particles. Further, the surface of the fine particles may be treated with a so-called coupling agent before use. By such surface treatment, the affinity of the fine particles with other components can be increased when the coat layer is formed.

A particularly preferred fine particle is silica sol.
Silica sol is generally produced by removing alkali ions from sodium silicate, as shown in “Polymer Processing”, 1974, Volume 23, pp. 149-155. is there. As the silica sol, a silica sol containing no impurities can be used, but such a silica sol tends to aggregate because the colloidal state is unstable. Therefore, a silica sol whose surface is stabilized by sodium ions, aluminum ions, ammonium ions or the like is preferable. Commercially available products include Snowtex (trade name) manufactured by Nissan Chemical Industries, Ltd., Cataroid (trade name) manufactured by Catalysts & Chemicals Co., Ltd., and Ludox manufactured by du pont.
(Product name), Nal of Nalco Chemical Company
coag (brand name), Symon of Monsanto
(Product name) can be used. Furthermore, a silica sol obtained by dispersing silica powder obtained by vapor-phase thermal decomposition of silicon tetrachloride in water is a stable silica sol and can be suitably used. Examples of such silica sol include Aerosil (trade name) of Nippon Aerosil Co., Ltd.

In the present invention, the polyester resin and / or the polyurethane resin is coated on the polyester film as a coating liquid. In the coating liquid,
In order to improve the coatability, a lubricant, an antistatic agent, an antifoaming agent or the like may be contained within a range that does not impair the effects of the present invention.

The release polyester film of the present invention comprises
A method of coating the unstretched polyester sheet with the coating solution, and then sequentially or simultaneously biaxially stretching and then heat treating, or coating the uniaxially stretched film with the coating solution,
Then, it is obtained by, for example, a method of performing heat treatment after stretching in the direction perpendicular to the uniaxial stretching direction. Then, if necessary, the polyester film before being coated with the coating liquid may be subjected to a physical treatment such as corona treatment or ultraviolet treatment. The polyester resin and the polyurethane resin forming the coat layer are used alone or as a mixture in an arbitrary ratio.

The above unstretched polyester sheet can be obtained by melt-extruding polyester into a sheet at 270 to 320 ° C. and then cooling and solidifying at 40 to 70 ° C. The above-mentioned coating method is not particularly limited, and may be any method as long as it can be thinly coated. For example, there may be mentioned a method using a reverse roll coater, a gravure coater, a rod coater, and an air doctor coater, which is shown in “Coating Method” by Yuji Harazaki, published by Maki Shoten, 1979. Further, the above stretching,
It is possible to adopt a stretching method that is a combination of roll stretching and stenter stretching.

In particular, the following manufacturing method is a preferred method recommended. That is, first, by the roll stretching method, 6
The film is stretched 2 to 6 times at 0 to 150 ° C., then the obtained uniaxially stretched polyester film is coated with a coating solution, and then, with or without appropriate drying, the above stretching direction in a tenter is adjusted. Is stretched 2 to 6 times in the perpendicular direction at 80 to 150 ° C., and further heat treated at 150 to 250 ° C. for 1 to 600 seconds.

[0029] In the polyester film for release of the present invention, strength suitable for coating PVC, i.e., it is preferred that the breaking strength of ^{10kg / mm 2 ~40kg / mm 2} . Also, considering the heat resistance during coating,
It is preferable that the shrinkage percentage when heat-treated at 150 ° C. for 5 minutes is 5% or less. The thickness of the base polyester flume is preferably in the range of 3 to 500 μm,
The thickness of the coat layer is preferably in the range of 0.01 to 5 μm, more preferably 0.02 to 1 μm. When the thickness of the coat layer is less than the above range, it is difficult to obtain a coat layer having a uniform thickness, and when it exceeds the above range, the slipperiness is lowered and the handling becomes difficult.

[0030]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist. In the following examples and comparative examples, "part" means "part by weight". In addition, each measurement item was measured according to the following method.

(1) Evaluation of releasability A vinyl chloride emulsion (G-576 manufactured by Nippon Zeon Co., Ltd.) was coated on the side of the coat layer of the polyester film for release.
After drying at 140 ° C. for 2 minutes, it is aged at 200 ° C. for 2 minutes to form a polyvinyl chloride thin film having a thickness of 70 μm. An adhesive tape having a width of 15 mm (cellophane tape manufactured by Nichiban Co., Ltd.) is pressure-bonded onto the vinyl chloride thin film, and the peel strength between the release polyester film and the vinyl chloride thin film is obtained by a tensile tester. The peel strength is shown in units of g / 15 mm width. (2) Intrinsic viscosity of polyester 1 g of polymer is mixed with phenol / tetrachloroethane = 50
It is dissolved in 100 ml of a mixed solvent of 50/50 (weight ratio) and measured. The measurement temperature was 30 ° C. (3) Average particle size of particles The particles are dispersed in alcohol and measured with a Coulter counter.

Example 1 Polyester containing 600 ppm of amorphous silica having an average particle diameter of 1.6 μm and having an intrinsic viscosity of 0.66 was melted at 295 ° C. and extruded in a sheet form on a cooled rotating drum to obtain a blank. An oriented sheet was obtained. Then, after stretching 3.5 times in the longitudinal direction at 95 ° C., a polyurethane resin (“HYDRAN AP-4” manufactured by Dainippon Ink and Chemicals, Inc.) was formed on one surface thereof.
0 ") 70 parts and a polyester resin (" Finetex ES-670 "manufactured by Dainippon Ink and Chemicals, Inc.) 30
And a mixed solution consisting of parts. Subsequently, the above film was introduced into a tenter, subjected to a preheating process, stretched at 110 ° C. in the transverse direction by 3.6 times, and then heat-treated at 230 ° C. for 10 seconds. The obtained polyester film for release had a film thickness of 75 μm and a coat layer thickness of about 0.1 μm.

The above-mentioned releasing polyester film had a peel strength of 90 g / 15 mm width and had appropriate adhesiveness and releasability. Further, when the peeled surface of the PVC thin film was observed after the PVC thin film and the polyester film were rapidly peeled off, it had a good gloss. Moreover, the peeling side of the PVC thin film was painted with an oil-based marker, but there was no abnormal cissing and the printability was good.

Example 2 Aside from using a polyester containing no amorphous silica,
A non-oriented sheet was obtained by the same method as in Example 1. Then, after stretching 3.5 times in the longitudinal direction at 95 ° C., polyurethane resin (“Hydran AP-40”) 6 was applied to one surface thereof.
5 parts and polyester resin ("Finetex ES-
670 ") and 30 parts of colloidal silica (" Snowtex YL "manufactured by Nissan Chemical Industries, Ltd.). Subsequently, transverse stretching and heat treatment were performed in the same manner as in Example 1 to obtain a releasing polyester film having a film thickness of 75 μm and a coat layer thickness of about 0.1 μm. The release polyester film had appropriate adhesiveness and release properties as in Example 1, and the release surface of the vinyl chloride thin film had good gloss.

Example 3 A glossiness of 30% was obtained in the same manner as in Example 1 except that 1.8% by weight of amorphous silica having an average particle diameter of 2.4 μm and polyester having an intrinsic viscosity of 0.66 were used. A polyester film for release having a surface roughness (Ra) of 0.34 μm was obtained. The above-mentioned releasing polyester film was obtained in Example 1
Similar to the above, it had appropriate adhesiveness and releasability, and the release surface of the PVC thin film had a matte tone.

Comparative Example 1 A mold releasing polyester film was obtained in the same manner as in Example 1 except that the mixed solution of the polyurethane resin and the polyester resin was not coated. The release polyester film was not peeled between the polyester film and the PVC thin film, and the peel strength could not be measured. When the PVC thin film was forcibly peeled off without using cellophane tape, the PVC thin film was broken.

[0037]

EFFECTS OF THE INVENTION According to the present invention described above, a vinyl chloride resin casting can exhibit sufficient adhesiveness, is excellent in releasability, and does not impair the ink adhesiveness of the vinyl chloride sheet after peeling. A polyester film for release is provided.

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Claims (2)

[Claims] 1. A mold releasing polyester film comprising a polyester film and a coating layer of a polyester resin and / or a polyurethane resin provided on at least one surface of the polyester film. 2. The mold releasing polyester film according to claim 1, which is used for casting a vinyl chloride resin.