JP2506287B2 - Mold release polyester film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release polyester film, and more particularly to a release polyester film used during casting of vinyl chloride resin.

[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 for 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, an adhesive processed vinyl chloride mark sheet, 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 the release film, the release property between the polyester film and the vinyl chloride sheet is heavy, and the gloss of the release surface of the vinyl chloride 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 pressure-sensitive adhesive. Further, since the silicone resin is transferred to the peeling surface of the vinyl chloride, there is a drawback that the ink adhesiveness when printing on the vinyl chloride surface is deteriorated.

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 release polyester film is peeled off. However, also in the production of the retroreflective 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
Castin made of vinyl chloride resin, which has excellent peelability and does not impair the ink adhesion of the resin sheet after peeling
The purpose is to provide a release polyester film used for molding.

[0008]

That is, the gist of the present invention is to provide (I) on at least one surface of a polyester film.
A coating layer comprising a polyolefin and / or a modified product thereof and (II) one or more resins selected from the group consisting of polyurethane resins, polyacrylic resins and polyester resins. Characteristic, vinyl chloride
It exists in a release polyester film used when casting a nil resin .

The present invention will be described in detail below. In the release 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 that the above polyester contains fine particles 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 release surface of the resin sheet has a uniformly roughened and matte surface.

In the release polyester film of the present invention, the first component constituting the coat layer is polyolefin and / or its modified product (hereinafter referred to as "polyolefin or the like").
Abbreviated). Examples of the polyolefin and the like include compounds having the following compounds (1) to (5) as a basic skeleton. The polyolefin or the like is used by being dissolved or dispersed in water.

(1) A wax composed of a homopolymer or copolymer of an α-olefin unsaturated hydrocarbon such as ethylene, propylene, 1-butene and 4-methyl-1-pentene.
Resin, rubber-like material. Examples of the corresponding compound include polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene-propylene copolymer, ethylene-1-butene copolymer, propylene-
Examples thereof include 1-butene copolymer.

(2) A rubber-like copolymer of two or more of the above α-olefins and a conjugated or non-conjugated diene. Examples of the corresponding compound include ethylene-propylene-budadiene copolymer, ethylene-propylene-dicyclopentadiene copolymer, ethylene-propylene-ethylidene norbornene copolymer, ethylene-propylene-1,5.
-Hexadiene copolymer, isobutene-isobrene copolymer, etc.

(3) A copolymer of the above-mentioned α-olefin and a conjugated or non-conjugated diene. Applicable compounds include:
Examples thereof include ethylene-butadiene copolymer and ethylene-ethylidene norbornene copolymer. (4) A copolymer of the above-mentioned α-olefin (particularly ethylene) and vinyl acetate and a completely or partially saponified product thereof. (5) A graft polymer obtained by grafting the above-mentioned conjugated or non-conjugated diene, vinyl acetate or the like to the homo- or copolymer of the above α-olefin, and a completely or partially saponified product thereof.

In order to dissolve or disperse the above-mentioned polyolefin or the like in water and to stabilize it so as not to cause aggregation, a conventionally known surfactant may be used in combination, or hydrophilic such as water-soluble polyester. A method of coexisting a water-soluble polymer during dispersion is also effective. By introducing a vinyl compound having a hydrophilic group such as a carboxylic acid group, a sulfonic acid group, an amino group, a polyether, an alkylolamide group or a salt thereof by copolymerization or grafting onto the skeleton of polyolefin or the like. It can also facilitate water solubilization or water dispersion.

Particularly preferred polyolefins and the like are prepared by introducing the above-mentioned vinyl compound having a hydrophilic group,
It is a soapless or self-emulsifying polyolefin or the like dispersed or dissolved in water without using a surfactant or another hydrophilic polymer.

In the release polyester film of the present invention, the second component constituting the coating layer is one or more resins selected from the group consisting of polyurethane resins, polyacrylic resins and polyester resins. (Hereinafter, referred to as “aqueous polymer”). These are aqueous polymers that dissolve, emulsify or suspend in water, and can be used alone or in admixture of two or more. The water-based polymer is used for coating the polyester film with the above-mentioned polyolefin or the like with good appearance and improving the adhesiveness between the coating layer and the polyester film. Then, the above-mentioned polyolefin or the like is preferably mixed with an aqueous polymer and coated.

As the polyurethane resin, an aqueous urethane resin containing a polyisocyanate, a polyol, a chain extender, a crosslinking agent and the like as main raw material components can be used. In making the urethane resin aqueous, it is a general method to use a polyisocyanate, a polyol and a chain extender having a hydrophilic group introduced therein. Alternatively, a method of reacting an unreacted isocyanate group of polyurethane with a compound having a hydrophilic group can be adopted. Also,
As the polyurethane resin, a resin having a polysiloxane group, a fluorinated alkyl group, an epoxy group, or the like modified by graft or block polymerization may be used.

As the polyacrylic resin, use is made of an aqueous polyacrylic resin which is mainly composed of alkyl acrylate and / or alkyl methacrylate and is copolymerized with a vinyl monomer having a reactive functional group. You can Examples of the reactive functional group include a carboxyl group or salts thereof, an acid anhydride group, a sulfonic acid group or salts thereof, an amide group, an amino group, a hydroxyl group, an epoxy group and the like. In particular, an aqueous polyacrylic resin containing a carboxyl group, an amino group, a hydroxyl group, an epoxy group or the like is preferable from the viewpoint of adhesiveness to a polyester film and coating strength. Further, as the polyacrylic resin, a resin modified by grafting or block polymerizing a compound having a polysiloxane group, a fluorinated alkyl group, an epoxy group or the like may be used.

Examples of the dicarboxylic acid component of the polyester resin include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid and 2,5-naphthalenedicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, azelaic acid and sebacic acid, and oxybenzoic acid. Oxycarboxylic acids such as acids and their ester-forming derivatives can be used.
On the other hand, as the glycol component of the polyester resin,
Aliphatic glycols such as ethylene glycol, 1,4-butanediol, diethylene glycol and triethylene glycol, alicyclic glycols such as 1,4-cyclohexanedimethanol, aromatic diols such as p-xylenediol, polyethylene glycol and polypropylene glycol. Poly (oxyalkylene) glycols such as polytetramethylene glycol can be used.

As the polyester resin, not only the saturated linear polyester composed of the above-mentioned ester-forming component but also a compound having a trivalent or higher valent ester-forming component or a compound having a reactive unsaturated group is used as a polyester component. You can do it. The polyester resin preferably has a sulfonic acid, a carboxylic acid, or a salt thereof in order to improve solubility and dispersibility in water. As the polyester resin, a resin modified by grafting a compound having a carbon double bond having a polysiloxane group, a fluorinated alkyl group, an epoxy group, an amide group or the like may be used.

In the present invention, in order to enhance the adhesion between the coat layer and the polyester film and to improve the releasability between the coat layer and the sheet layer such as vinyl chloride, the polyolefin in the coat layer and / or its modification are modified. The proportion of the product is preferably 1 to 80% by weight based on the total weight of the coat layer.
If it is less than 1% by weight, the releasability is insufficient, and if it exceeds 80% by weight, the adhesiveness of the coat layer to the polyester film is not sufficiently improved.

Inorganic or organic fine particles may be dispersed in the above-mentioned polyolefin and / or its modified product in order to impart slippage to the release 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 fine particles having inorganic fine particles as a 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, pages 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 are Snowtex (trade name) manufactured by Nissan Chemical Industries, Ltd., Cataloid (trade name) manufactured by Catalysts & Chemicals Co., Ltd., and Ludox manufactured by du pont.
(Trade name), Nal of Nalco Chemical Company
coag (trade name), monsanto's symton
(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.

Further, in the present invention, it is preferable to use a crosslinking agent as a component of the coating liquid in order to improve the solvent resistance, water resistance, blocking resistance and scratch resistance of the coating layer. As the crosslinking agent, a methylolated or alkylolated urea-based compound, melamine-based compound, guanamine-based compound, acrylamide-based compound, amide-based compound, epoxy compound, aziridine compound, polyisocyanurate, block polyisocyanate, silane coupling agent, titanium Examples thereof include coupling agents, zirco-aluminate coupling agents, heat, peroxides, photoreactive vinyl compounds and photosensitive resins. In addition, in order to improve coatability, the coating liquid may contain a lubricant, an antistatic agent, an antifoaming agent, etc. 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 a 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 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 coating method is not particularly limited, and any method may be used 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,
A stretching method in which the roll method stretching and the stenter method stretching are combined can be adopted.

In particular, the following manufacturing method is a recommended and preferred method. That is, first, by the roll stretching method,
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.

In the release polyester film of the present invention, the strength suitable for resin coating, that is,
It is preferred breaking strength is ^{10kg / mm 2 ~40kg / mm 2} . Also, considering the heat resistance during coating, 15
It is preferable that the shrinkage percentage when heat-treated at 0 ° C. for 5 minutes is 5% or less. The thickness of the base polyester film is preferably in the range of 3 to 500 μm, and 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.

[0031]

EXAMPLES The present invention will be described in more detail 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 methods.

(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 (cellophane tape manufactured by Nichiban Co., Ltd.) having a width of 15 mm is pressure-bonded onto the above-mentioned vinyl chloride thin film, and the peel strength between the releasing polyester film and the vinyl chloride thin film is obtained by a tensile tester. Peel strength is shown in units of g / 15 mm width. (2) Appearance of coat layer The presence or absence of coat unevenness was judged with the naked eye, and when there was substantially no coat unevenness, it was defined as “good”.

(3) Printability of vinyl chloride sheet: The vinyl chloride sheet obtained by peeling from the release polyester film is marked with a paint on the peeled surface and evaluated by the presence or absence of cissing. The case where there was substantially no cissing was defined as “good”. (4) Intrinsic viscosity of polyester 1 g of polymer is used as 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. (5) Average particle size of particles The particles are dispersed in alcohol and measured with a Coulter counter.

The contents of each component shown in Table 1 are as follows. (1) All the polyolefins are dispersions, and the content of each polyolefin is as follows. Polypropylene (1): "High Tech E-4333N" manufactured by Toho Chemical Industry Co., Ltd. Polypropylene (2): "High Tech E-4B" manufactured by Toho Chemical Industry Co., Ltd. Polyethylene: "Cybinol X288-" manufactured by Saiden Chemical Industry Co., Ltd.
369E-1 "

(2) Polyurethane resin: "HYDRAN AP-4" manufactured by Dainippon Ink and Chemicals, Inc.
0 ”(3) Polyester resin (1):“ FINETEX E ”manufactured by Dainippon Ink and Chemicals, Inc.
S-670 "(4) Polyester-based resin (2):" Plus Coat RZ-124 "manufactured by Goyo Chemical Co., Ltd. (5) Alkyrol melamine:" Beckamine J10 manufactured by Dainippon Ink and Chemicals, Inc. "
1 ”(6) Colloidal silica:“ Snowtex YL ”manufactured by Nissan Chemical Industries, Ltd.

Examples 1 to 4 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 into a sheet on a cooled rotating drum. A non-oriented sheet was obtained. Then, after stretching 3.5 times in the longitudinal direction at 95 ° C., one side thereof was coated with a coating liquid having the composition shown in Table 1. Subsequently, the above film was introduced into a tenter, subjected to a preheating step, 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. As shown in the evaluation results in Table 1, the release polyester film was excellent in all evaluation items.

Example 5 Example 1 was repeated except that a polyester containing no amorphous silica was used and a coating solution having the composition shown in Table 1 was used.
A polyester film for release having a film thickness of 75 μm and a coat layer thickness of about 0.1 μm was obtained by the same method as described above. As shown in the evaluation results in Table 1, the release polyester film was excellent in all evaluation items, and the release surface of the PVC thin film had good gloss.

Example 6 A glossiness of 30% was obtained in the same manner as in Example 1 except that a polyester containing 1.8% by weight of amorphous silica having an average particle diameter of 2.4 μm and an intrinsic viscosity of 0.66 was 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
It is excellent in all evaluation items as well as
The peeled surface of the PVC thin film was matte.

Comparative Example 1 A releasing polyester film was obtained in the same manner as in Example 1 except that the coating liquid was not used. 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.

[0040]

[Table 1] Example 1 2 3 4 5 <Structure of coat layer> [Polyolefin] Polypropylene (1) 5 ----- Polypropylene (2) --- --- 10 Polyethylene-10 10 --- Polyolefin wax ----- 70- [Water-soluble polymer] Polyurethane resin 6560-60-55 Polyester resin (1) 2020-2020 Polyester resin (2) -80- [Others] Alkyrol melamine 1010101010 Colloidal silica − − − − 10 <Evaluation result> Coat layer appearance Good Good Good Good Good Good Peel strength (g / 15 mm width) 40 35 130 50 30 Printability of PVC sheet Good Good Good Good Good Good

[0041]

EFFECTS OF THE INVENTION According to the present invention described above, a releasing polyester capable of exhibiting sufficient adhesiveness, excellent in releasability and not impairing the ink adhesiveness of the resin sheet after peeling. A film is provided.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location B29L 7:00 B29L 7:00 (72) Inventor Shinichi Kinoshita 1000 Kamoshida-cho, Midori-ku, Yokohama-shi, Kanagawa Address Diafoil Co., Ltd. Central Research Laboratory (56) Reference JP-A-63-189227 (JP, A) JP-A-1-202449 (JP, A)

Claims (1)

(57) [Claims] 1. A (I) polyolefin and / or a modified product thereof on at least one surface of a polyester film,
(II) Casting of vinyl chloride resin , characterized by comprising a coating layer containing one or more resins selected from the group consisting of polyurethane resins, polyacrylic resins and polyester resins Release polyester film used at times .