JPH10166517A - Easily bondable film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a film, which has an excellent adhesion under a high temperature and highly humid atmosphere and favorable transparency and light transmission, by a method wherein a specified primer layer and a specified acrylic resin layer are laminated onto one side of a polyester-based resin film in the named order. SOLUTION: This easily bondable film is produced by laminating a primer layer containing a styrene-butadiene-based copolymer and a crosslinker and an acrylic resin layer containing an acrylic latex and a melamine-based crosslinker onto at least one side of a polyester resin film in the order named. The time, at which a primer layer coating liquid is applied, is set to be before or after the biaxial stretching or just before the application of a surface layer material. After the primer layer coating liquid containing the styrene-butadiene- based copolymer is applied on the polyester-based resin film base, the acrylic resin layer coating liquid containing the acrylic latex and the melamine-based crosslinker is applied on the resultant base in order to produce this laminated film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film exhibiting easy adhesion, and more particularly to an antireflection layer for OCR equipment and an OCR film.
The present invention relates to an easily adhesive film having excellent transparency and adhesiveness applicable to a wide range of fields such as HP films and labels.

[0002]

2. Description of the Related Art Polyester resin films, particularly biaxially stretched films of polyethylene terephthalate, have excellent mechanical properties, flame resistance, chemical resistance, etc., and are therefore used for magnetic tapes, photographic films, packaging films, OHP films or recent years. Recently, the demand for such substrates as antireflection films for general-purpose OCR equipment has been remarkably growing.
In these applications, the film is required to have adhesiveness. For example, printing inks and laminating materials for packaging films, photosensitive layers formed on base films for photographic films, magnetic recording layers for magnetic tapes, and UV absorbing films for UV protection films for OCR equipment. It is desired that the adhesiveness with the paint is good. However, polyester film has crystal orientation,
High surface cohesion and poor adhesion to various materials.

[0003] As means for improving the surface properties of the polyester film, corona treatment, plasma treatment, flame treatment and the like are known, and some of them are used. However, these means are intended to improve the adhesiveness by physically changing the shape of the film surface, and have the drawback that the performance decreases over time and the transparency also decreases.

As another method for overcoming this drawback, there is a method of applying an easily adhesive coating on a film and providing a primer layer. As the primer layer, an organic solvent type and an aqueous type are used, and an aqueous type is preferable from the viewpoint of safety, hygiene and resource saving such as deterioration of the environment due to volatilization.

[0005] Therefore, it has been proposed to form this primer layer using an aqueous coating agent, for example, a water-soluble or water-dispersible polyurethane or copolymerized polyester resin. However, the above-mentioned primer layer has good adhesion to the polyester film depending on the physical properties, but has low affinity for the coating agent, adhesive, ink, etc. to be laminated, or conversely, adhesion to those layers. It was difficult to select a material having sufficient adhesiveness as an intermediate layer, for example, when the adhesiveness was improved, the adhesiveness to a polyester film was reduced. Further, there are problems that the films are blocked by changes in temperature and humidity during storage, and that it is difficult to apply a surface layer agent such as diazo paint or UV ink uniformly.

In order to solve this problem, for example, Japanese Patent Application Laid-Open No. 1-108037 discloses a polyester film having a primer layer formed by crosslinking an acrylic resin and an acrylic-modified polyester resin. −
No. 22899 discloses polyester films each having a layer containing a styrene-butadiene resin or an acrylonitrile-butadiene resin and a specific polyester resin. These are primer layers made of a material that improves the adhesiveness to both the polyester resin and the surface layer agent.Although the adhesiveness is improved compared to the conventional one, the stability and transparency in a high-temperature, high-humidity environment are improved. Sex was not yet satisfactory.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to
Excellent adhesion to various paints including inks, binders used for adhesives and photosensitive layers even in high-temperature and high-humidity atmospheres, and good adhesion with good transparency and light transmittance An object of the present invention is to provide a polyester film.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies and as a result,
The inventors have found that the above problem can be solved by sequentially forming a primer layer having a specific adhesive strength and an acrylic resin layer containing an acrylic emulsion on a polyester resin film, and have completed the present invention. That is, the easily adhesive film of the present invention is a primer layer containing a styrene-butadiene copolymer and a cross-linking agent or a primer layer containing an acryl-modified polyester resin and a cross-linking agent on at least one surface of a polyester resin film. And an acrylic resin layer containing an acrylic latex and a melamine crosslinking agent are sequentially laminated.

When an ultraviolet curable resin layer is formed on the surface of the acrylic resin layer of the obtained easily adhesive film and subjected to a tape peeling test, the strength of the film not peeled off at any interface between adjacent layers. It is characterized by having.

In the present invention, an acrylic resin layer is laminated on a film base via a primer layer,
Since this primer layer is a layer containing a styrene-butadiene-based copolymer and a cross-linking agent and a layer containing an acrylic-modified polyester resin and a cross-linking agent, both the polyester film and the acrylic resin layer are favorably used. Adhesion and sufficient peel resistance are achieved, and since all materials are excellent in transparency, the laminated easily adhesive film also has excellent transparency and light transmittance.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, the polyester resin (hereinafter, appropriately referred to as polyester) constituting the film includes a line synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Saturated polyester. Specific examples of the polyester that can be used in the present invention include polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, polybutylene terephthalate, poly (1,4-cyclohexylene dimethylene terephthalate), and polyethylene-2,6-phthalenedicarboxylate. And the like, and polyethylene terephthalate, polyethylene naphthalate, and the like are preferable from the viewpoint of availability, economy, and effect. Further, as a material of the film, a copolymer of these or a blend thereof with a small proportion of another resin can be used as long as the effects of the present invention are not impaired. Further, in the polyester film, a small amount of inorganic or organic fine particles such as titanium oxide, calcium carbonate, silica, barium sulfate, and silicone such as inorganic filler, acrylic, benzoguanamine, and Teflon for improving the slipperiness. , An organic filler such as epoxy, an adhesion improver such as polyethylene glycol (PEG) and sodium dodecylbenzenesulfonate, and an antistatic agent.

The polyester film of the present invention is obtained by melt-extruding the above polyester resin into a film,
It can be formed by oriented crystallization by longitudinal and transverse biaxial stretching and crystallization by heat treatment. Known methods and conditions can be appropriately selected and used for the method and conditions for producing these films.

The thickness of the polyester film used here is not particularly limited and can be appropriately selected depending on the purpose of use of the film. In general, the thickness is preferably from 5 μm to 500 μm.

[0015] The easily adhesive film of the present invention is characterized in that an acrylic resin layer is formed on the film substrate with a primer layer interposed therebetween. A (meth) acrylate resin having a transition point of 20 to 80 ° C. is exemplified. This (meth) acrylate resin can be synthesized by radical polymerization of an acrylic monomer. Examples of the monomer include alkyl (meth) acrylates (alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, 2-ethylhexyl, cyclohexyl) Group): 2
Hydroxy-containing monomers such as -hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate: (meth) acrylamide, N-alkyl (meth) acrylamide, and N, N-dialkyl (meth) acrylamide (as the alkyl group , Methyl group,
Ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.): N-alkoxymethyl (meth) acrylamide and N, N-dialkoxymethyl (Meth) acrylamide (as an alkoxy group,
Methoxy, ethoxy, butoxy, isobutoxy, etc.), N-methylol (meth) acrylamide, N, N
-Amide group-containing monomers such as dimethylol (meth) acrylamide and N-phenyl (meth) acrylamide: epoxy group-containing monomers such as glycidyl (meth) acrylate and acrylglycidyl ether: (meth) acrylic acid, itaconic acid, maleic acid, Fumaric acid, crotonic acid, styrenesulfonic acid and its salts (sodium salt, potassium salt, ammonium salt, tertiary amine salt, etc.)
Monomers containing a carboxyl group or a salt thereof, such as:
Monomers of anhydrides such as maleic anhydride and itaconic anhydride: vinyl isocyanate, allyl isocyanate, styrene, vinyl methyl ether, vinyl trialkoxycin, alkyl maleate monoester, acrylonitrile, methacrylonitrile, vinylidene chloride, ethylene, propylene, Examples thereof include monomers such as vinyl chloride, vinyl acetate, acrylonitrile, and butadiene. These monomers can be used as a copolymer by using two or more kinds.

The acrylic resin material used herein preferably has a secondary transition point of 20 ° C. or higher. If the secondary transition point is lower than 20 ° C., a blocking phenomenon occurs between the films due to the adhesion of the primer layer. There is a fear that this is not preferable. Also,. Further, when the secondary transition point is higher than 80 ° C., the formed layer is hard and brittle, so that there is a disadvantage that the adhesiveness to the polyester film is reduced. The secondary transition point is preferably from 30 to 60C, more preferably from 40 to 60C.

The acrylic resin in the acrylic resin layer is preferably in the form of an emulsion and dispersed in a suitable solvent, that is, latex from the viewpoint of the effect. In the present invention, it is necessary to add a crosslinking agent to the resin layer made of the acrylic latex in order to improve the moisture resistance. Examples of the cross-linking agent include polyvalent metal salt-based, polyisocyanate-based, polyepoxy-based, and melamine-based cross-linking agents. Among them, melamine-based cross-linking agents are particularly preferable from the viewpoint of transparency and adhesiveness.

Known additives such as plasticizers, thickeners and tackifiers can be used in combination with the latex as long as the effects of the present invention are not impaired.

The thickness of the acrylic resin layer can be selected according to the required adhesive strength.
About 0 ml / m ² and a film thickness after drying of 0.1 to 0.5
It is preferably about μm.

Next, the primer layer will be described. The first primer layer used in the present invention is characterized by containing a styrene-butadiene copolymer (hereinafter, appropriately abbreviated as SBR) and a crosslinking agent. SBR is a copolymer mainly composed of styrene and butadiene, and means a copolymer of other components as necessary. It is known that this copolymer can obtain various physical properties by adjusting the content ratio of styrene and butadiene. When forming a primer layer as in the present invention,
The styrene-butadiene copolymer is preferably a latex. Specifically, SBR latex (JSR (trade name) from Nippon Synthetic Rubber Co., Ltd., Nipol (trade name) from Zeon Corporation, Nogatex (trade name) from Sumitomo Nogatack Co., Ltd.) ), Asahi Dow Asahi Dow Latex (trade name), and other commercially available products sold by Dainippon Ink and Chemicals, Inc. and overseas manufacturers.

In the case of latex, the particle size of the dispersion particles is
It is 5 μm or less, preferably 1 μm or less, and more preferably 0.2 μm or less. When the particle diameter is large, there are problems such as easy aggregation of the particles in the coating step and poor film transparency and gloss. If it is necessary to further reduce the thickness of the coating layer, it is necessary to reduce the particle size accordingly.

The content ratio of styrene / butadiene in the styrene-butadiene copolymer of the primer layer is 50 /
It is preferably about 50 to 80/20. The ratio of SBR contained in the latex is 30 as solid weight.
It is preferably from 50% by weight to 50% by weight.

A crosslinking agent is added to the primer layer in order to improve the physical properties of the SBR. The crosslinking agent used here is preferably a triazine-based crosslinking agent.

The second primer layer that can be used in the present invention comprises:
It contains an acrylic-modified polyester resin and a crosslinking agent.
The acrylic modified polyester resin used here is
The main chain is a copolymerized polyester resin, refers to a graft or block copolymer in which the side chain is acrylic, and as the acrylic monomer introduced into the side chain of the resin, those exemplified previously in the acrylic resin layer Can be mentioned.

As the polyester component, a linear polymer synthesized from a polybasic acid or an ester-forming derivative thereof and a polyol or an ester-forming derivative thereof is preferable. As the polybasic acids and polyols used here, known ones or two or more can be selected and used. As an acrylic modified polyester resin,
Specifically, for example, those commercially available from Takamatsu Yushi Co., Ltd. as Pesresin A-515GB (trade name) can be suitably used. Further, the crosslinking agent used in the resin layer is preferably a melamine-based crosslinking agent.

In preparing the easily adhesive film of the present invention, a primer layer coating solution containing a styrene-butadiene copolymer or an acrylic-modified polyester resin and a crosslinking agent is applied onto a polyester resin film substrate. It is preferable to form a laminated film by applying a coating liquid containing the acrylic resin.

The apparatus used for applying the coating solution for the primer layer to the polyester film or for applying the coating solution for the acrylic resin layer on the formed primer layer is described in Yuji Harazaki, “Coating Method”, Shinshoten 1979 Reverse coater, gravure coater,
Any of known coating apparatuses such as a rod coater and an air doctor coater can be used.

The time for applying the primer layer coating solution to the polyester film is before biaxial stretching, after biaxial stretching, or immediately before applying the surface material. Also,
No. 8470 or the like, a method of applying a coating agent to a uniaxially stretched polyester film by a roll stretching method, performing appropriate drying or not performing drying, and immediately stretching in a direction perpendicular to the preceding stretching direction and heat-treating. Can also be applied (hereinafter, abbreviated as a coating stretching method). According to the coating stretching method, the coating layer can be dried at the same time as the stretching, and by stretching the coating layer, the coating thickness can be reduced, and a wide width which has been difficult by a method other than the coating stretching method. Is obtained.

The thickness of the primer coating layer on the polyester film is preferably in the range of 0.01 μm to 0.5 μm. If the thickness of the coating layer is less than 0.01 μm, it is difficult to apply the coating uniformly, so that uneven coating is likely to occur on the product, or the adhesiveness with the acrylic resin layer to be laminated is insufficient. If the thickness of the coating layer exceeds 0.5 μm, the films may easily adhere to each other or the light transmittance of the entire film may be reduced.

Each of the primer layers of the present invention is excellent in blocking resistance and does not require the addition of a matting agent. Therefore, the haze value is as low as 1% or less. Also the film itself obtained by laminating. For example, a high total light transmittance of 92% or more can be achieved.

Each of the above-mentioned coating liquids may contain, if necessary, a stickiness improver, a coatability improver, an antifoaming agent, an ultraviolet absorber, an antioxidant, an antistatic agent, a lubricant, inorganic fine particles, a dye and a pigment. Etc. may be contained.

In order to evaluate the adhesiveness of the thus obtained easily adhesive film, an ultraviolet curable resin layer was formed on the surface of the acrylic resin layer, and a tape peeling test was performed. It is desirable to have a strength that does not peel at any of the interfaces. To explain the evaluation method, the easily adhesive film (15 cm
UV curable resin (U) on the surface of the acrylic resin layer
V-cured resin CT: Fuji Hunt Electronics Co., Ltd.)
Was applied so that the film thickness after drying was 8.5 μm.
The resin is dried in an oven at 00 ° C. for 1 minute and irradiated with ultraviolet rays for 2 minutes to cure the resin. Then, the surface is cut with a cutter (N
(T cutter), cross cut into 1.5 mm square to a depth reaching the surface of the polyester film to form 100 cut pieces on the surface. This specimen was subjected to 50 ° C. and 95% RH.
Was stored in an oven for 100 hours, and a cellophane tape (Cellotape: manufactured by Nichiban Co.) was adhered to the entire surface thereof, and a peeling test was performed. This operation is performed on five specimens, and the number of cut pieces adhered to the tape and peeled off is measured.
Here, a sample without any peeling is regarded as a pass.

The easily adhesive film of the present invention is formed by laminating the above-mentioned primer layer and acrylic resin layer on at least one surface of a polyester film substrate. In this case, a primer layer and an acrylic resin layer are formed on both sides of the film substrate. At this time, the two primer layers may be the same or different.

In particular, when used for a film for an OCR device that requires transparency and high light transmittance, a primer layer mainly composed of acrylic-modified polyester is provided on the side in contact with the OCR device, and SBR is provided on the opposite surface. It is preferable to form a primer layer mainly composed of

The easily adhesive film of the present invention has excellent adhesion to various surface layer materials, and is useful as a base material for packaging materials, photosensitive materials, drafting materials, electrophotographic materials, magnetic recording materials, etc. OHP
It is particularly suitable as a substrate for a film or an antireflection film for an OCR device.

[0036]

The present invention will be described in detail with reference to specific examples below, but the present invention is not limited to these examples. (Example 1) Polyester film substrate A biaxially stretched polyester film having a thickness of 175 µm was used as a substrate. Primer layer styrene-butadiene copolymer latex 10 parts by weight (solid content 40%, styrene / butadiene weight ratio = 70/30) 2,4-dichloro-6-hydroxy-s-triazine sodium salt 8% aqueous solution 1.3 parts by weight Part 88.8 parts by weight of water 6 ml / m ^{2 of} a coating solution of the above composition
Apply and dry at 160 ° C for 5 minutes, thickness 0.24μm
Was formed. Acrylic resin layer Acrylic resin (HA-16: manufactured by Nippon Acrylic Co.) 5 parts by weight Colloidal silica 0.04 parts by weight (Snowtex ZL: manufactured by Nissan Chemical Industries) Polyoxyethylene alkyl ether 0.2 parts by weight Melamine resin 0. 4 parts by weight (Sumitec Resin M-3: manufactured by Sumitomo Chemical Co., Ltd.) 94.36 parts by weight of water 7 ml of a coating solution of the above composition on the formed primer layer
/ M ^{2 and} dried at 160 ° C for 5 minutes to give a thickness μ
m of an acrylic resin layer was formed to obtain an easily adhesive film. (Example 2) Polyester film substrate The same polyester film as in Example 1 was used as a substrate. Primer layer acrylic-modified copolymerized polyester resin 8 parts by weight (Vethresin A-515GB: manufactured by Takamatsu Yushi) 0.2 parts by weight of sodium dodecyl diphenyl ether disulfonate Melamine resin 0.4 parts by weight (Sumitec Resin M-3: manufactured by Sumitomo Chemical Co., Ltd.) 91.4 parts by weight of water A coating solution of the above composition was applied to one side of the film substrate at 7 ml / m ^2.
Apply and dry at 160 ° C for 5 minutes to a thickness of μm
Was formed. Acrylic resin layer Acrylic resin (R-3380A: manufactured by Dainippon Ink) 5 parts by weight Colloidal silica 0.04 parts by weight (Snowtex ZL: manufactured by Nissan Chemical Industries) Polyoxyethylene alkyl ether 0.2 parts by weight Melamine resin 0. 4 parts by weight (Sumitec Resin M-3: manufactured by Sumitomo Chemical Co., Ltd.) 94.36 parts by weight of water 7 ml of a coating solution of the above composition on the formed primer layer
/ M ^{2 and} dried at 160 ° C. for 5 minutes to a thickness of 0.1
An acrylic resin layer having a thickness of 2 μm was formed to obtain an easily adhesive film. (Comparative Example 1) Example 1 was repeated except that an acrylic resin layer was formed directly on the surface of a film substrate without forming a primer layer.
An easily adhesive film was obtained in the same manner as described above. (Comparative Example 2) Example 2 was repeated except that an acrylic resin layer was formed directly on the surface of a film substrate without forming a primer layer.
An easily adhesive film was obtained in the same manner as described above. (Comparative Example 1) An easily adhesive film was obtained in the same manner as in Example 1 except that a polyolefin resin (Chemipearl S-120: manufactured by Mitsui Petrochemical Industries) was used instead of SBR as the main component of the primer layer. [Evaluation of easy-adhesive film] (Adhesive strength: tape peeling test) An ultraviolet-curable resin (UV-curable resin CT: manufactured by Fuji Hunt Electronics Co., Ltd.) was applied to the surface of the acrylic resin layer of the obtained easy-adhesive film (15 cm square). ) Is applied so that the film thickness after drying is 8.5 μm, dried in an oven at 100 ° C. for 1 minute, and irradiated with ultraviolet rays for 2 minutes using P647-GA manufactured by Dainippon Screen Co., Ltd. to cure the resin. After curing, the surface is cross-cut with a cutter (NT cutter) to a depth of 1.5 mm square to a depth reaching the surface of the polyester film to form 100 cut pieces on the surface.

The specimen was stored in an oven at 50 ° C. and 95% RH for 100 hours, and a cellophane tape (Cellotape: manufactured by Nichiban) was applied to the entire surface thereof, and a peeling test was performed. This operation was repeated five times, and the number of cut pieces adhered to the tape and peeled was counted. Here, it was judged that there was no peeling at all, Δ was attained peeling, and X was attained all peeling.

The results are shown in Table 1 below. (Light transmittance) Total light transmittance was measured by NDH manufactured by Nippon Denshoku Industries Co., Ltd.
It measured using -1001DP. The results are shown in Table 1 below.

[0039]

[Table 1]

As is clear from Table 1, the easily adhesive film of the present invention has excellent adhesiveness with the layer formed on the surface, and the film between the laminates of the polyester film substrate, the primer layer and the acrylic resin layer. No peeling was seen. Moreover, it turned out that all have high light transmittance. (Application Example 1) A layer is formed on the back surface of the easily adhesive film obtained in Example 1 with the same configuration as in Example 2, and a double-sided easily adhesive film having a primer layer and an acrylic resin layer on both surfaces is produced. did. The back surface of this film was adhered to the CRT surface with an ultraviolet curable adhesive. On one surface side, a thickness of 8.
An antireflection layer was formed via a 5 μm UV curable resin (CT: manufactured by Fuji Hunt Electronics Co.) layer to form an antireflection film.

The antireflection film had good light transmittance, showed no delamination of the adhesive layer and the like even when used for a long period of time, and exhibited excellent adhesion for a long period of time.

[0042]

The easily adhesive film of the present invention exhibits excellent adhesion to various paints such as UV inks, adhesives and binder resins used for the photosensitive layer even in a high-temperature and high-humidity atmosphere. Further, it has an excellent effect that transparency and light transmittance are good.

Claims (2)

[Claims] 1. A polyester resin film comprising, on at least one surface thereof, a primer layer containing a styrene-butadiene copolymer and a crosslinking agent, and an acrylic resin layer containing an acrylic latex and a melamine crosslinking agent. And an easy-adhesive film characterized by being sequentially laminated. 2. A laminated layer of a primer layer containing an acrylic-modified polyester resin and a crosslinking agent and an acrylic resin layer containing an acrylic latex and a melamine crosslinking agent are sequentially laminated on at least one side of a polyester resin film. An easily-adhesive film, characterized in that: