JPH0258584A - Tacky film for improving scratch resistance and plastic plate having improved scratch resistance - Google Patents

Abstract

PURPOSE:To obtain the title economic film having excellent film adhesiveness, scratch resistance, transparency and weather resistance by coating the back of a plastic film subjected to hard coat processing with an acrylic adhesive composition having blister resistance. CONSTITUTION:The back of a plastic film having the surface subjected to hard coat processing is coated with an adhesive composition consisting essentially of a copolymer which comprises (A) 50-85wt.% monomer unit of acrylic acid ester base, (B) 1-30wt.% monomer unit of polar acrylic monomer base and (C) 5-40wt.% macromonomer unit containing a polymer chain and a polymerizable functional group at the end in the weight ratio of the component B/C of 0.02-6 and has 150,000-2,000,000 weight-average molecular weight and -60-60 deg.C glass transition temperature to give the aimed film.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an adhesive film for improving the scratch resistance of plastics and a plastic plate with improved scratch resistance. More specifically, the adhesive film for improving the scratch resistance of plastics is made by applying a blister-resistant adhesive composition to the back side of a plastic film whose surface has been hard-coated, and the improved scratch resistance obtained by pasting the above-mentioned adhesive film. Regarding the plastic plate.

[Prior Art J] Plastic materials are excellent in terms of low cost, light weight, workability, impact resistance, etc., and are used in large quantities for various purposes. However, plastics, especially thermoplastics, have the disadvantage of having a low surface hardness and being easily scratched, that is, having poor scratch resistance. In order to improve this drawback, a method of coating the surface with a highly hard material, that is, a hard coat treatment, is often used.

Conventional hard coat treatment involves applying a hard coat material directly to the plastic surface and curing it to impart scratch resistance. However, this method cannot be used for plastics that are susceptible to hard coating materials or their solvents, and when hard coating materials are heated and cured, it can only be applied to plastics that can withstand the heat. Furthermore, this method requires complicated steps and time to hard coat each plastic molded article, which is economically disadvantageous.

As a method to improve the above drawbacks, the surface of a plastic film with high heat resistance and solvent resistance, such as polyester film or polyimide film, is hard coated, an adhesive is applied to the back side of the film, and this is applied to the plastic surface. A method of improving scratch resistance by pasting has also been carried out. According to this method, the film wound into a roll can be continuously hard-coated, and the hard-coat treatment can be performed just by pasting the film, so it is easy to operate and has excellent heat resistance and solvent resistance. It is extremely advantageous because it can be applied even to low-grade plastics.

However, when an adhesive sheet or label using a conventional film with gas barrier properties such as polyester as a base material is attached to a molded product made of styrene resin or polycarbonate resin, the gap between the sheet or label and the resin adherend is Spots of air bubbles appear on the skin, and blisters such as blisters and floats often occur.

The occurrence of such blisters makes the appearance extremely unsightly, especially when pasted together with a label, and can also cause the label to fall off.Particularly in the case of transparent labels, the adhesive surface may become avatar-like or It becomes transparent and cloudy, and the appearance is inevitably impaired.

This phenomenon occurs because the plastic film used as the base sheet of the adhesive sheet acts as a barrier layer for trace gases generated between the adhesive layers, so there is no place for the gas to escape, and blisters occur as spots of gas bubbles. I think that the.

Therefore, it may be possible to eliminate the blister condition by interposing a ventilation layer made of paper or porous polyurethane between the film and the adhesive layer, but this method reduces the total thickness of the adhesive sheet. In addition to being thicker, problems arise such as the transparency is impaired and it cannot be used as a transparent label.

It has also been revealed that rubber adhesives made of styrene-isoprene-styrene block copolymers or styrene-butadiene-styrene block copolymers have anti-blister properties with certain formulations. Since these are all rubber-based, they have the disadvantage that the weather resistance of the adhesive layer portion is poor.

[Problems to be Solved by the Invention] The present invention provides an adhesive film that prevents the occurrence of blisters and has excellent adhesive strength and weather resistance as an adhesive film used when attaching a hard coated film to plastics. The purpose is to provide

[Means for Solving the Problem] As a result of extensive research by the present inventors in order to develop an adhesive sheet with excellent blister resistance that is used when attaching Bartco-1 processed film to plastic,
Focusing on the fact that blisters are caused by trace gases generated from inside the resin adherend, we created an adhesive composition that contains acrylic ester monomer units, polar acrylic monomer units, polymer chains, and polymerizable functionalities at the ends. By using a copolymer having a specific molecular weight and glass transition temperature as a main component, which contains macromonomer units having a group in a predetermined ratio, It was discovered that the polymer chain in the macromonomer unit prevents the occurrence of blisters, and good adhesion and adhesive retention are obtained, thereby achieving the above object.Based on this knowledge, the present invention was completed. reached.

That is, in the present invention, on the back side of a plastic film whose surface has been hard coated, (A) 50 to 85% by weight of acrylic acid ester monomer units, (B) 30% by weight of a single position of a polar acrylic monomer, and (C ) Macromonomer unit 5 having a polymer chain and a polymerizable functional group at the end
~40% by weight, the weight ratio of the (B) units to the (C) units is 0.02 to 6, and the weight average molecular weight is 1.
50,000 to 2,000,000 and a glass transition temperature of 160 to 60°C.
The present invention provides an adhesive film for improving the scratch resistance of plastics, and a plastic plate to which the adhesive film is attached.

The present invention will be explained in detail below.

The pressure-sensitive adhesive sheet of the present invention is obtained by coating a blister-resistant adhesive composition on the back side of a plastic film whose surface has been hard-coated, and the copolymer which is the main component of the adhesive composition is (A) an acrylic ester monomer unit, (B) a polar acrylic monomer unit, and (C) a macromonomer unit.

Examples of the unit (A), that is, an acrylic acid ester monomer unit, include an acrylic acid alkyl ester unit and a methacrylic acid alkyl ester unit in which the alkyl group has 1 to 14 carbon atoms. Monomers constituting such acrylic acid ester monomer units include acrylic acid or methacrylic acid, and carbon atoms having 1 to 14 carbon atoms.
alcohols, e.g., TLF methanol, ethanol,
n-7' lovanol, impropatol, n-butanol, imbutanol, n-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, l- Methyl = 1-pentanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 2-ethyl-1-butanol, 3
, 5.5-trimethyl-1-hexanol, 3-heptatool, 2-ethylhexanol, n-decanol, n
Examples include esters obtained from -dodecanol and the like. Among these acrylic acid ester monomers, n-butyl acrylate and 2-ethylhexyl acrylate are preferably used. These monomers may be used alone or in combination of two or more.

The monomers constituting the (B) unit of the copolymer, that is, the polar acrylic monomer unit, include polar groups such as carboxyl group, hydroxyl group, amino group, amide group, epoxy group, cyano group, incyanate group, etc. Examples include acrylic monomers having one or more of at least one group selected from among them. Examples of such polar acrylic monomers include (meth)
Acrylic acid, 2-hydroxyethyl (meth)acrylate, 2-aminoethyl (meth)acrylate, (meth)acrylamide, glycidyl (meth)acrylate, (meth)
Acrylonitrile, 2-isocyanoethyl (meth)acrylate, itaconic acid, maleic acid, etc., have polar groups,
Among the copolymers, those in which the polar group is present as a side chain can be mentioned. These polar acrylic monomers may be used alone or in combination of two or more.

The (C) unit of the copolymer, that is, the macromonomer unit, has a polymer chain and a polymerizable functional group at the end, and the polymer chain includes, for example, a styrene unit, a methyl methacrylate unit, or a combination of these. Examples include copolymer chains consisting of units such as and 50 mol% or less of acrylonitrile units, vinyl acetate units, etc. This polymer chain has a molecular weight of too
.

~30,000 and the glass transition temperature is 30'O
The above are preferred.

Further, the polymerizable functional group is not particularly limited as long as it is a functional group that can be copolymerized with the above-mentioned acrylic acid ester monomer or polar acrylic monomer. Examples of such polymerizable functional groups include methacryloyl groups, allyl groups, and vinylbenzyl groups.

By copolymerizing such a macromonomer having a polymer chain and a polymerizable functional group at the end with the above-mentioned acrylic acid ester monomer and polar acrylic thread yarn, the polymer in the macromonomer can be used as a branch component. Graft copolymers with chains can be easily obtained.

There are no particular restrictions on the method for producing the R macromonomer, and various known methods may be used, such as (1) first producing a lipping polymer anion constituting the polymer chain portion of the macromonomer, and then adding methacrylic acid chloride or the like to this. (2) Polymerize a radically polymerizable polymer such as methyl methacrylate in the presence of mercaptoacetic acid as a chain transfer agent to obtain an oligomer having a terminal carboxyl group, and then macromonomerize with glycidyl methacrylate. (3) A method in which an oligomer having a terminal hydroxyl group is obtained using mercaptoethanol as a chain transfer agent, and then macromonomerized with hydroxyethyl methacrylate. (4) A method in which a mercaptan chain transfer agent containing a polymerizable functional group is used as a chain transfer agent. (5) Using vinyl phenylketene methyltrimethylsilyl acetal as a polymerization initiator and a fluorine compound as a cocatalyst, ionically polymerizing a vinyl seventh polymer having a carbonyl group or a cyano group. Any method can be used, such as the method of

Regarding the content ratio of each unit of the copolymer in the present invention, (A) acrylic acid ester monomer unit is 50
~85% by weight, (B) polar acrylic yarn upper unit is 1
~30% by weight and (C) macromonomer units are 5-40
It is necessary that the weight ratio of the (B) units to the (C) units be within the range of 0.02 to 6.

If the content of each unit deviates from the above-mentioned range, the copolymer will have poor blister resistance or adhesive performance, and the object of the present invention will not be fully achieved.

Further, in the present invention, the weight average molecular weight of the copolymer must be in the range of 150,000 to 2,000,000, preferably 260,000 to 1,500,000, and more preferably 300,000 to 1,000,000. If the weight average molecular weight is less than 150,000, the adhesive's holding power may be low, while if it exceeds 2,000,000, the workability of coating etc. tends to deteriorate.

Furthermore, the glass transition temperature of the copolymer is -60 to 60°
C1 preferably needs to be in the range of -30 to 20°C. If the glass transition temperature is less than 160°C, the adhesive force will not be sufficient, and if it exceeds 60°C, the ball tack will tend to decrease.

The method for producing the copolymer in the present invention includes, for example, (
1) Acrylic acid ester monomer 1 A polar acrylic monomer and a macromonomer having a polymer chain and a polymerizable functional group at the end are simultaneously copolymerized in the presence of a radical polymerization initiator such as azobisisobutyronitrile. Method, (2) First, an acrylic acid ester monomer,
For example, a polar acrylic monomer having a reactive group such as a carboxyl group or a hydroxyl group is copolymerized to produce a copolymer having a reactive group in the side chain, and then the copolymer is bonded with the reactive group. A method of reacting a macro segment consisting of a polymer chain having a terminal reactive group such as a cyanate group, a hydroxyl group, or a carboxyl group; (3) a method of reacting a macro segment consisting of a polymer chain having a terminal reactive group such as a cyanate group, a hydroxyl group, or a carboxyl group; After copolymerizing the monomer and polar acrylic monomer, styrene,
A method such as graft copolymerization of heptamers such as methyl methacrylate and acrylonitrile can be used.

In methods (2) and (3) above, the copolymerization reaction of an acrylic ester monomer, a polar acrylic monomer, and a macromonomer is not utilized, but the resulting copolymer has a final structure ( This is the same as that produced by method D, and falls within the concept of a copolymer according to the present invention.

According to the research of the present inventors, monomers such as styrene and methyl methacrylate are simply copolymerized with acrylic acid ester monomers and polar acrylic monomers, and styrene units, methyl methacrylate units, etc. are converted into main chain units of the copolymer. The anti-blister effect that is the objective of the present invention cannot be obtained by simply blending ordinary polystyrene, polymethacrylate, or other resins with a copolymer of an acrylic acid ester monomer and a polar acrylic seventh polymer. I can't get it.

From these facts, in the copolymer according to the present invention,
The side chain polymer chains form microdomains in the copolymer, and the microphase separation structure is effective in absorbing and diffusing trace gases generated from resin adherends that cause blistering. Seem.

The film to be hard coated must have excellent heat resistance and solvent resistance, and can be made from synthetic resins such as polyester, polypropylene, polyethylene, polyamide, polyimide, polyphenylene sulfide, polymethylpentene, and polyethersulfone. A sheet or film consisting of the above can be used.

Hard coating can be applied to the above base film by continuously applying the hard coating agent using a coating method such as a bar coater, roll coater, or gravure coater, or by batch application using a spin coater, etc. etc. A silane type, acrylic type, etc. can be used as the hard coat agent, and a hard coat layer can be obtained by heat curing, ultraviolet rays, or electron beam curing.

The thickness of the film to be hard coated is usually 5 μm to 2
00 μm, particularly a range of 25 μm to 75 μm is suitable.

The adhesive film of the present invention can be produced by applying an adhesive composition containing the above-mentioned copolymer as a main component to the back side of the above-mentioned hard-coated film by a conventionally used method. .

Alternatively, a hard coat treatment may be performed after applying the adhesive composition in advance.

In addition, to further improve the durability of the adhesive sheet,
Anti-aging agents such as ultraviolet absorbers and antioxidants can also be added.

Furthermore, although the present invention is often applied to transparent plastics, particularly plastic window materials, in the case of window materials, it may be necessary to adjust sunlight. In other words, it is often required to have a sunlight adjustment function at the same time. The method of attaching a film such as the one of the present invention is the most excellent method for imparting solar control functions to plastic window materials.

Therefore, it is extremely effective to simultaneously provide the above-mentioned pressure-sensitive adhesive sheet with a sunlight adjustment function. Methods of imparting solar control functions to adhesive sheets include methods of coloring the base film with organic or inorganic pigments, metallizing the film surface (metallizing), and methods of applying light of specific wavelengths such as ultraviolet and infrared. Although there are methods of containing blocking substances inside or on the surface, metallized films are the most suitable for efficiently regulating sunlight. As the metal to be metalized, aluminum, chromium, gold, etc., or oxides such as tin, silicon, titanium, indium, zirconium, etc. can be used, but aluminum is preferred because of its ease, low cost, and solar control effect. Vapor deposition is particularly preferred. For the metallization, ordinary methods for metallizing plastic films, such as vacuum evaporation, cathode sputtering, and ion blasting, can be used.

Recently, conductive plastics have been attracting attention,
By attaching a film having a conductive function, a plastic having a conductive surface can be easily obtained. Especially the transparent groove′
If it has IIL#R capability, it becomes a functional plastic with unique optical and electrical properties. In the present invention, a conductive function can be imparted to the film at the same time as the hard coat treatment.

Methods for imparting conductive functions to films include forming metals such as gold and silver, or oxides such as tin and indium-tin alloys, on the film surface using methods such as vacuum evaporation or sputtering; There are a method of applying a coating agent containing a conductive substance such as the above on the surface of the film, and a method of kneading the conductive substance into the film.

The present invention also includes a plastic material with improved scratch resistance, in which the hard-coated film described above is attached to a plastic material using a blister-resistant adhesive. The plastic material used in the present invention is used particularly in applications where scratch resistance is required, i.e., those whose surfaces are susceptible to scratches, and where surface scratches significantly impair the appearance and reduce commercial value, such as transparent window materials, casings, etc. , exterior parts, etc. Examples of the glass used for this purpose include polycarbonate, acrylic resin such as methyl methacrylate, and polystyrene.

To apply a hard-coated film to a plastic material, you can apply the film while spraying water onto the window, or use a laminator, in the same way as when applying it to a regular glass window.

[Example J] Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

In addition, each physical property was determined according to the method shown below.

(1) Viscosity Using a BM type viscometer manufactured by Tokyo Keiki, in an atmosphere of 23°C, N
o, 4 o-ter The measurement was carried out under the conditions of 60 rpm. Values are expressed in centiboise.

(2) CCP800 manufactured by Tosoh Corporation using molecular weight THF as the fluid phase
0 Measured using a GPC device, and the weight average molecular weight (Q w ) is shown using polystyrene as a standard material.

(3) Glass transition temperature Reovipron DDV-II manufactured by Orientic Co., Ltd.
-Measurement was made using the new method using EP at 3.5 Hz.

In addition, each abbreviation in the table means the following.

2EHA 2-Ethylhexyl Niacrylate BA Butyl Niacrylate AA Niacrylic Acid HEMA: Methacrylic Strict 2-Hydroxyethyl AN-6
: Methacryloyl-terminated poly(styrene-acrylonitrile copolymer) C"J Nialon macromonomer AN-6) C-4500 manufactured by Agosei Co., Ltd.: Methacryloyl-terminated polystyrene (manufactured by Sartomer Corporation: Chemlink C-4500) Adhesive production example A Reflux cooling 5 equipped with a container, nitrogen inlet tube, thermometer, and stirring blade.
2-ethylhexyl acrylate 809, acrylic acid 3g, methacryloyl-terminated styrene-acrylonitrile copolymer (trade name: AN
-6 [manufactured by Toagosei Co., Ltd.]) 179, a, a'-azobisisobutyronitrile 0.539, ethyl acetate 230 g
was added and stirred for 30 minutes under a nitrogen stream, and then heated to 60'C! The temperature was raised to , and the reaction was continued for 24 hours.

The obtained polymer solution was transparent, had a viscosity of 3,000 cps at a concentration of 35% by weight, and a weight average molecular weight of 680,000.

Table 1 shows the monomer charge composition and the physical properties of the polymer.

Adhesive Production Examples B, C, and D Adhesives were produced in the same manner as in Example 1, except that the composition of the seven pots was changed as shown in Table 1.

Table 1 shows the monomer charge composition and the physical properties of the polymer.

Comparative Example of Adhesive Production x, y Using a two-component monomer that does not contain the (B) component, an adhesive was produced in the same manner as the production method of Adhesive A with the seven-component composition shown in Table 1. .

Table 1 shows the monomer charge composition and the physical properties of the polymer.

(Leaving space below) Example 1 A hard coat agent (Aronix, manufactured by Toagosei Co., Ltd.) was coated with a polymer solution of adhesive A on a 25 μm thick polyester film (Lumirror, manufactured by Toagosei Co., Ltd.), and the film was coated with a hard coating agent (manufactured by Toagosei Co., Ltd., Aronix). A hard coat layer was provided. Next, apply a polymer solution of adhesive A to the opposite side of the hard coat treated surface.
A hard coat adhesive sheet was prepared by heating and drying. Paste this on a polycarbonate board and heat it at 80°C1.
After a 24-hour accelerated deterioration test, the surface was tested using a Gakushin type abrasion tester (
(manufactured by Toyo Seiki Co., Ltd.) was coated with steel wool, and the scratch resistance and appearance were evaluated after 500 reciprocations.

The evaluation is a haze meter (BGM-2, Suga Test Il!
Co., Ltd.) and Guo7. ) -9-(VG-ID, E
(manufactured by Ippon Isshoku Kogyo Co., Ltd.). The results are shown in Table 2.

Examples 2 to 4 A polycarbonate plate with a hard-coated adhesive sheet pasted was prepared in the same manner as in Example 1 except that the adhesives were replaced with B, C, and D, and after an accelerated deterioration test in the same manner as in Example 1. The scratch resistance was evaluated. The results are shown in Table 2.

Comparative Example 1 An adhesive sheet made of a 25 μm thick polyester film (manufactured by Toshiku Co., Ltd., Lumirror) that was not hard coated and coated with the same blister-resistant adhesive as in Example 1 was attached to an acrylic resin plate. Similarly, the scratch resistance after the accelerated deterioration test was evaluated.

The results are shown in Table 2.

Comparative Example 2.3 Adhesives X and Y, which are not included in the present invention, were applied to a polyester film hard-coated in the same manner as in Example 1; an adhesive sheet was attached to a polycarbonate plate;
The scratch resistance after the accelerated deterioration test was evaluated in the same manner as in Example 1. The results are shown in Table 2.

(Left below) Scratch resistance test results after accelerated test 1) There is no change in the adhesive layer, but there are many scratches on the surface. 2) There are no scratches on the surface, but many blisters occur on the adhesive layer. As is clear from the results in Table 2, the material of Example 1 showed no abnormality in appearance even after the severe abrasion test, and maintained high levels of haze and gloss. In comparison, in Comparative Example 1, in which only a polyester film without hard coating treatment was attached, many scratches occurred on the surface, the haze was significantly reduced, and no surface protection effect was observed. Furthermore, in Comparative Examples 2 and 3, in which adhesives not included in the present invention were used, there were no scratches on the surface, but blisters were generated on the surface of the adhesive layer, resulting in a significant decrease in transparency.

[Effects of the Invention] According to the present invention, by hard-coating a film and attaching it to plastics, it is possible to efficiently and economically apply hard-coat treatment to all kinds of plastics.

Furthermore, by using a specific copolymer in the adhesive layer, the hard-coated adhesive M film of the present invention can be applied to plastic plates without causing poor appearance due to blistering or poor adhesion. , it is possible to efficiently and economically produce a plastic material that firmly adheres to a film and has excellent scratch resistance, transparency, and weather resistance.

Claims (1)

[Scope of Claims] 1. On the back side of a plastic film whose surface has been hard coated, (A) 50 to 85% by weight of acrylic acid ester monomer units, (B) 30% by weight of a single position of polar acrylic monomer, and ( C) consists of a polymer chain and 5 to 40% by weight of macromonomer units having a polymerizable functional group at the end, and the weight ratio of the (B) units to the (C) units is 0.
02 to 6, and the weight average molecular weight is 150,000 to 2 million,
An adhesive film for improving the scratch resistance of plastics, which is coated with an adhesive composition containing as a main component a copolymer having a glass transition temperature of -60 to 60°C. 2. On a plastic plate, a hard-coated plastic film is coated with (A) 50 to 85% by weight of acrylic acid ester monomer units, (B) 30% by weight of a polar acrylic monomer at a single position, and (C) polymer chains and terminals. 5-40% by weight of macromonomer units having polymerizable functional groups
, the weight ratio of the (B) units to the (C) units is 0.02 to 6, and the weight average molecular weight is 150,000 to 200.
10, A plastic plate with improved scratch resistance to which an adhesive composition mainly composed of a copolymer having a glass transition temperature of -60 to 60°C is attached as an adhesive.