JPH0586346A - Pressure-sensitive adhesive for masking and adhesive film comprising the same - Google Patents

Abstract

(57) [Summary] [Purpose] A pressure-sensitive adhesive for masking and its adhesive film that can reliably prevent the infiltration of the treatment liquid into the non-treatment area during treatment such as plating, etching, and degreasing in an acid or alkaline aqueous solution. I will provide a. [Structure] (Meth) acrylic acid alkyl ester-based polymer having a weight average molecular weight of 150,000 to 2,000,000, and oil-soluble phenol resin 1 to 100 parts by weight of the polymer.
40 parts by weight are compounded to form a pressure sensitive adhesive. Further, this adhesive is subjected to a cross-linking treatment so that the cross-linking degree of the (meth) acrylic acid alkyl ester-based polymer is 10% by weight.
After being immersed in the aqueous sodium hydroxide solution at 60 ° C. for 3 days, the gel fraction is 30 to 95% and the swelling degree is 1.5 to 1
Set to 5 times.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive for masking for masking an untreated portion during treatment such as plating, etching and degreasing in an acid or alkaline aqueous solution, and an adhesive film therefor.

[0002]

2. Description of the Related Art In various surface treatments in an acid or alkaline aqueous solution, a method is known in which a non-treated portion is masked with a pressure-sensitive adhesive film. As an adhesive used for this purpose, silicone is used. In general, pressure sensitive adhesives and thermoplastic adhesives are used.

[0003]

Silicone pressure-sensitive adhesives mainly prevent the infiltration of the liquid in the mask portion by the water repellency based on the low surface energy of the silicone. Although a great effect is recognized in the electroless plating by the method, the electrolytic degreasing and the electrolytic plating in the alkaline treatment bath may cause the liquid to infiltrate into the mask portion.

Thermoplastic adhesives are mainly used as masking adhesives for continuous stripe plating on metal strips, and their function is to adhere by plasticizing the adhesives by thermocompression bonding. By physically increasing the adhesion between the metal surface of the body and the adhesive, it prevents the infiltration of liquid,
Oxidation of the surface of the metal strip was promoted by the heat at the time of thermocompression bonding, and the adhesion of the metal plating was sometimes deteriorated. Moreover, the effect of preventing the infiltration of the liquid is mainly the physical adhesion between the surface of the adherend and the adhesive, so that a surfactant or the like is added to the treatment liquid to prevent the treatment liquid from contacting the metal. When the wettability was high and the treatment time was long, liquid infiltration sometimes occurred.

In view of the above-mentioned conventional problems, the present invention provides a pressure-sensitive adhesive for masking and its adhesive film for an acidic treatment liquid as well as an alkaline treatment liquid.
It is an object of the present invention to provide a material that can reliably prevent the infiltration of liquid.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above object, and as a result, have found that a specific amount of an oil-soluble phenol-based polymer is added to a (meth) acrylic acid alkyl ester polymer having a specific structure. The present inventors have completed the present invention by knowing that a pressure-sensitive adhesive obtained by adding a resin has excellent performance for masking such as a beetle.

That is, the present invention has a weight average molecular weight of 1
To 50,000 to 2,000,000 (meth) acrylic acid alkyl ester-based polymer (hereinafter referred to as acrylic polymer), 1 to 40 parts by weight of oil-soluble phenol resin is added to 100 parts by weight of this acrylic polymer. The present invention also relates to a pressure-sensitive adhesive for masking, and more particularly to the above-mentioned adhesive in which the above-mentioned acrylic polymer is cross-linked and its gel fraction and swelling degree are set within specific ranges.

According to the present invention, a layer of the pressure-sensitive adhesive having the above-mentioned structure crosslinked as described above is provided on a plastic film having a thickness of 6 to 250 μm in a thickness of 1 to 100 μm. It relates to the film.

According to the adhesive film of the present invention, when it is used as a mask material for an untreated portion in various surface treatments with an acid or an alkali, an oil-soluble phenol resin is blended in an acrylic polymer. According to the layer separation effect due to not necessarily sufficient compatibility, the non-polar alkyl group part in the oil-soluble phenolic resin bites into the acrylic polymer and is oriented, while the polar hydroxyl group is When the surface of the adherend is particularly a metal, a strong hydrogen bond is generated with the surface of the adherend, which effectively prevents the treatment liquid from entering the mask portion.

The acrylic polymer constituting the pressure-sensitive adhesive layer is brought into contact with the adhesive treatment liquid in the acid or alkali treatment liquid by being crosslinked to an appropriate degree of crosslinking. Part of the part is appropriately dissolved and swelled, thereby improving the wettability and adhesion between the adhesive and the adherend, and as a result, it is possible to further prevent the treatment liquid from entering the mask part.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylic polymer according to the present invention comprises a monomer mixture containing a (meth) acrylic acid alkyl ester as a main component and a functional group-containing monomer usually added thereto, using a polymerization initiator. Then, it is obtained by radical polymerization according to a conventional method.

The (meth) acrylic acid alkyl ester is
An alkyl acrylate or methacrylic acid alkyl ester in which the number of carbon atoms of the alkyl group is usually 1 to 12, and examples thereof include ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, butyl methacrylate, 2-ethylhexyl methacrylate. Etc.,
The 1 type (s) or 2 or more types are used. If desired, a part of the (meth) acrylic acid alkyl ester may be replaced with another monomer such as styrene or vinyl acetate.

The functional group-containing monomer not only contributes as a component for improving the activity and wettability of the surface of the adherend, but also acts as a cross-linking point to give good results in improving cohesive force. Examples of such monomers include carboxyl group-containing monomers such as acrylic acid, methacrylic acid and maleic anhydride, and hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and 2-hydroxyvinyl ether. Monomers, amino group-containing monomers such as N.N-dimethylaminoethyl acrylate and N.N-dimethylaminoethyl methacrylate, and amide group-containing monomers such as acrylic acid amide and methacrylic acid amide. A monomer having an epoxy group, a phosphine group, a sulfone group or the like can also be used.

Such a functional group-containing monomer is usually used in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the (meth) acrylic acid alkyl ester.
If the amount is too small, the activity and wettability of the adherend surface will be insufficient, or the crosslinking will be insufficient and the cohesive force will decrease. On the other hand, if the amount is too large, the adhesiveness may be deteriorated or the polymerization operation when forming the acrylic polymer becomes unstable.

The acrylic polymer in the present invention needs to have a weight average molecular weight in the range of 150,000 to 2,000,000, and particularly preferably in the range of 200,000 to 900,000. If the molecular weight is too low, the cohesive strength of the adhesive will decrease,
In addition, the chemical resistance to acids and alkalis decreases and the adhesive decomposes and elutes too much. On the other hand, if the molecular weight is too high, the initial adhesive properties deteriorate and the workability deteriorates.

As the oil-soluble phenol resin in the present invention, 100% phenol resin and natural resin-modified phenol resin are used.
Examples of the resin include a resin and a dry oil-modified resin, but there is no particular limitation as long as they are known to be oil-soluble. Examples of the p-alkylphenol used as a raw material for synthesizing a 100% phenol resin include p-tertiary butyl, p-tertiary amyl, and p-tertiary octylphenol.

Commercially available products of such oil-soluble phenol resin are, for example, Tamanor 510, 610, 581 under the trade name of Arakawa Chemical Industry Co., Ltd., and Sumirite under the trade name of Sumitomo Deyureze Co. Resin 12603, same PR
-22193, Tatsukyl 201, trade name of Sumitomo Chemical Co., Ltd., RP-45, trade name of Gunei Chemical Co., Ltd.
07 and the like.

The amount of the oil-soluble phenol resin used is 1 to 40 parts by weight, and particularly preferably 5 to 20 parts by weight, based on 100 parts by weight of the acrylic polymer. 1
If the amount is less than parts by weight, the sealability to an acid or alkali treatment liquid is not sufficient, and if it exceeds 40 parts by weight, the glass transition point of the entire adhesive increases, resulting in poor pressure-sensitive adhesiveness at room temperature. Become.

The pressure-sensitive adhesive for masking of the present invention contains the above-mentioned acrylic polymer and oil-soluble phenol resin as essential components, and if necessary, a plasticizer, a surfactant and a water-repellent agent. Various additives such as agents, colorants, fillers and adhesion-imparting resins can be added in appropriate amounts.

The pressure-sensitive adhesive for masking of the present invention containing such constituents is subjected to a cross-linking treatment by an appropriate means when it is used as a mask material to obtain a gel fraction and a swelling degree of the acrylic polymer. Is adjusted to an appropriate value.

That is, the degree of crosslinking of the acrylic polymer is 60 ° C. in a 10 wt% sodium hydroxide aqueous solution.
The gel fraction after soaking for 3 days at 30 to 95%, preferably 60 to 90%, and the swelling degree of 1.5 to 1
The cross-linking treatment is carried out so as to be 5 times, preferably 3 to 12 times. If the gel fraction and the degree of swelling are out of the above ranges, the effect of improving the adhesion to the adherend becomes poor, and
And the adhesive is dissolved and eluted too much, resulting in contamination of the processing liquid.

The above gel fraction means that after being immersed in a 10% by weight sodium hydroxide aqueous solution at 60 ° C. for 3 days, it is taken out and its dry weight (W _t ) is measured to obtain the initial dryness before immersion. Percentage to weight (W _o ), ie (W _t
It means a value calculated as / W _o ) × 100 (%). In addition, the degree of swelling means the initial volume (V
_o ) and the volume (V _t ) after being immersed and taken out under the above conditions
And means a value calculated as (V _t / V _o ).

The means for carrying out the crosslinking treatment in this way is arbitrary and is not particularly limited. For example, when an appropriate cross-linking agent such as a polyfunctional isocyanate, a methylol compound and an acid catalyst is added to the pressure-sensitive adhesive in advance to prepare an adhesive film, this is used as a support. After applying it on the plastic film, or once
After coating on a substrate and transferring it onto the support, it may be left standing at room temperature or under heating for crosslinking treatment.

In the adhesive film of the present invention, examples of the plastic film used as the support include:
Polyethylene, polypropylene, polyethylene terephthalate, etc., which may be made of a single material or a mixture of two or more kinds, or may be a laminated material and have a thickness of 6 to 25
A plastic film having a thickness of 0 μm, preferably 12 to 100 μm is used. This plastic film is preferably one that is not decomposed or deteriorated with respect to the processing liquid, but can be used if decomposition or deterioration is not remarkable depending on the processing conditions used. The thickness of the layer of the crosslinked pressure-sensitive adhesive provided on the plastic film as described above may be appropriately determined, but is usually 1 to 100 μm, preferably 2 to 50 μm. Is good.

[0025]

As described above, in the present invention, the oil-soluble phenol resin is added to the acrylic polymer which is the main component of the pressure-sensitive adhesive for masking, and the above-mentioned acrylic polymer is also used. By appropriately cross-linking the gel and setting the gel fraction and swelling to an appropriate range, the treatment liquid enters the mask portion as the non-treatment portion during treatment such as plating, etching, and degreasing in an acid or alkaline aqueous solution. Can be effectively prevented.

[0026]

EXAMPLES Next, examples of the present invention will be described to more specifically describe. In the following, "parts" means "parts by weight".

Example 1 40 parts of ethyl acrylate, 60 parts of butyl acrylate and 5 parts of acrylic acid were copolymerized in toluene using benzoyl peroxide as a polymerization initiator to give a weight average molecular weight of 300,000. A polymer solution having a solid content of 30% by weight containing the acrylic polymer was obtained. To this polymer solution, as a oil-soluble phenol resin,
20 parts of [trade name of Sumitomo Chemical Co., Ltd.] and 3 parts of toluene diisocyanate as a cross-linking agent were mixed to prepare a pressure-sensitive adhesive solution.

This adhesive solution was applied to the corona-treated surface of a polypropylene film having a thickness of 60 μm, which had been corona-treated on one side, so that the thickness after drying was 10 μm.
An adhesive film was prepared by drying at 0 ° C. for 5 minutes. The acrylic polymer constituting the pressure-sensitive adhesive layer in this film had a gel fraction of 70% and a swelling degree of 4 times.

Example 2 70 parts of ethyl acrylate, 30 parts of 2-ethylhexyl acrylate and 3 parts of acrylic acid were copolymerized in ethyl acetate using asobisisobutyronitrile as a polymerization initiator to obtain a weight. A polymer solution containing an acrylic polymer having an average molecular weight of 800,000 and having a solid content concentration of 30% by weight was obtained. To this polymer solution, 10 parts of Sumilite Resin PR-12603 [trade name of Sumitomo Deurez Co., Ltd.] as an oil-soluble phenol resin and 1 part of toluene diisocyanate as a crosslinking agent were mixed, and A solution of pressure sensitive adhesive was prepared.

This adhesive solution was applied to a polyethylene terephthalate film having a thickness of 24 μm and the thickness after drying was 2 μm.
It was applied so as to have a thickness of 0 μm and dried at 100 ° C. for 5 minutes to prepare an adhesive film. The acrylic polymer constituting the pressure-sensitive adhesive layer in this film had a gel fraction of 85% and a swelling degree of 7 times.

Example 3 50 parts of ethyl acrylate, 50 parts of butyl acrylate and 5 parts of acrylic acid were copolymerized in ethyl acetate using benzoyl peroxide as a polymerization initiator to give a weight average molecular weight of 70. A polymer solution having a solid content of 30% by weight containing an acrylic polymer was obtained. This polymer
Tamanoyl 610 as an oil-soluble phenolic resin in solution
A pressure sensitive adhesive solution was prepared by mixing 15 parts of [trade name of Arakawa Chemical Industry Co., Ltd.], 2 parts of toluene diisocyanate as a crosslinking agent, and 4 parts of a melamine crosslinking agent.

This adhesive solution was applied to one side of a polyethylene terephthalate film having a thickness of 24 μm so that the thickness after drying would be 5 μm, and dried at 100 ° C. for 5 minutes to prepare an adhesive film. did. The acrylic polymer constituting the pressure-sensitive adhesive layer in this film had a gel fraction of 80% and a swelling degree of 9 times.

Comparative Example 1 A pressure-sensitive adhesive solution was prepared in the same manner as in Example 1 except that an oil-soluble phenol resin was not blended, and this adhesive solution was used in the same manner as in Example 1. Then, an adhesive film was produced.

Comparative Example 2 A pressure-sensitive adhesive solution was prepared in the same manner as in Example 2 except that the oil-soluble phenolic resin was not added, and this adhesive solution was used in the same manner as in Example 2. Then, an adhesive film was produced.

Comparative Example 3 A pressure-sensitive adhesive solution was prepared in the same manner as in Example 3 except that the oil-soluble phenol resin was not mixed, and this adhesive solution was used in the same manner as in Example 3. Then, an adhesive film was produced.

In order to evaluate the characteristics of the adhesive films of Examples 1 to 3 and Comparative Examples 1 to 3 above, each adhesive film was laminated on a part of a copper plate which had been degreased with solvent in trichloroethylene in advance with a laminator roll at 5 kg / A sample was prepared by pressing once with a pressure of cm ² . Using this sample, the following treatment test was conducted to examine the infiltration state of the treatment liquid and the like. The results are shown in Table 1 below.

<Alkaline Electrolytic Degreasing Treatment> The composition of the liquid is sodium carbonate 50 g / liter, sodium triphosphate 30.
The sample was dipped in a beaker with g / liter and sodium hydroxide 15 g / liter, and the bath temperature was adjusted to 60 ° C., and the cathode side was treated at a current density of 5 A / dm ² for 1 minute. With respect to the sample after this alkaline electrolytic degreasing treatment, the effect of preventing the treatment liquid from entering the mask portion by the adhesive film was examined.
When it exceeded, it was evaluated as x.

<Activation treatment> Treatment was carried out by immersing in 10% by volume sulfuric acid at room temperature for 30 seconds. With respect to the sample after the activation treatment, the effect of preventing the processing liquid from penetrating the mask portion by the adhesive film is examined. When the penetration of the processing liquid is 0.5 mm or less, it is ○, and when it exceeds 0.5 mm, ×. evaluated.

<Electrolytic plating treatment> Commercially available electrolytic gold plating bath (gold content 10 g / liter, potassium gold cyanide 15)
g / liter, pH 5.5), and treated at a bath temperature of 60 ° C. and a current density of 1 A / dm ² for 3 minutes. With respect to the sample after the electrolytic plating treatment, the effect of preventing the treatment liquid from penetrating into the mask portion by the adhesive film and the effect of preventing bleeding of the plating on the boundary line between the matting and non-plating were examined, and the penetration of the processing liquid was 0.
The case of 5 mm or less and no smudge bleeding was evaluated as ◯, and the case where the infiltration of the treatment liquid exceeded 0.5 mm or the case of smudge bleeding was evaluated as x.

[0040]

[Table 1]

As is clear from the results shown in Table 1 above, according to the adhesive film of the present invention, the non-treated portion can be masked very effectively during treatment such as plating, etching and degreasing in an acid or alkaline aqueous solution. It turns out to be a thing.

Claims (3)

[Claims] 1. A (meth) acrylic acid alkyl ester-based polymer having a weight average molecular weight of 150,000 to 2,000,000, and 1 to 40 parts by weight of an oil-soluble phenol resin to 100 parts by weight of the polymer. A pressure-sensitive adhesive for masking. 2. A (meth) acrylic acid alkyl ester-based polymer is cross-linked, and as a degree of cross-linking, a gel fraction after dipping in a 10 wt% sodium hydroxide aqueous solution at 60 ° C. for 3 days is 30. ~ 95%, the same degree of swelling is 1.5
The pressure-sensitive adhesive for masking according to claim 1, which is about 15 times. 3. An adhesive film comprising a plastic film having a thickness of 6 to 250 μm and the pressure-sensitive adhesive for masking according to claim 2 having a thickness of 1 to 100 μm.