JP2806728B2 - Masking tape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a masking tape used for plating a metal of the same or different kind on a metal surface, and in particular, a masking tape which is excellent in anticorrosion properties of a non-plated portion and exhibits good masking performance. About tape.

[0002]

2. Description of the Related Art Conventionally, a method of coating a metal material surface with a metal of the same or different kind to impart new performance to the original metal material or protecting the metal material surface from oxidation or abrasion has been used. Widely used. As one of such methods, there is an electrolytic plating method. In the electroplating method, an aqueous solution of an acidic or alkaline metal electrolyte is used as a plating solution, and a metal in the plating solution is deposited on a metal surface by adding a charge to a portion to be plated.
A plating film is formed.

By the way, at the time of electrolytic plating, masking tape is applied to the non-plated portion so as to protect the non-plated portion so that the non-plated portion is not plated, or to make the plated portion a desired shape. May be affixed. This masking tape is generally called a plating masking tape.

[0004] In the plating masking tape, the plating line (the contour of the plated portion, that is, the boundary between the plated portion and the non-plated portion) is sharp, and it is easily peeled off after use without leaving adhesive residue. It is required that the adhesive does not contaminate the plating solution.

Conventionally, when a terminal portion of a printed circuit board is plated with gold, a plating masking tape as described above has been used to protect a portion that does not require plating. Also, when the plating masking tape is peeled off after use,
Adhesive component slightly remaining on printed circuit board (organic residue)
An organic solvent such as chlorofluorocarbon has been used to wash the glass.

However, in recent years, for environmental protection,
Fluorocarbon-free and organic solvent-free treatments are required, and thus it is strongly required that the adhesive component remaining after the masking tape has been peeled off can be washed with water.

[0007] Therefore, even in plating masking tapes, pressure-sensitive adhesives for exhibiting adhesiveness are required to have water solubility or water dispersibility. On the other hand, the above-mentioned plating solution is generally an acidic or alkaline metal electrolyte aqueous solution. Therefore, in order to prevent dissolution of the pressure-sensitive adhesive in the plating solution, the water-soluble or water-dispersible pressure-sensitive adhesive must be expressed only in a specific pH range. That is, it is necessary to use a water-soluble or water-dispersible pressure-sensitive adhesive that does not exhibit water-solubility and water-dispersibility in the pH range of the plating solution. However, the conventional water-soluble pressure-sensitive adhesive was not sufficient for use as a pressure-sensitive adhesive for a plating masking tape as described above.

[0008]

As a solution to the above-mentioned demand, although not yet known, Japanese Patent Application No. 4-30358.
No. 2 discloses a pressure-sensitive adhesive tape having a pH-selective pressure-sensitive adhesive layer, which loses tackiness by dissolving or absorbing water only in alkaline water.

However, not only the pressure-sensitive adhesive tape disclosed in Japanese Patent Application No. 4-303582, but also a plating masking tape using a water-soluble or water-dispersible pressure-sensitive adhesive, if it is immersed in a plating solution for a long time, Not a little plating solution was sometimes absorbed in the layer. Moreover, since the adhesive itself is hydrophilic, it may contain water.

As a result, the plating solution absorbed by the pressure-sensitive adhesive or the water contained in the pressure-sensitive adhesive is used to protect a metal material (for example, a circuit made of copper formed on a printed circuit board) formed of a masking tape during the plating process. Oxidation)
May corrode. This is presumably because, in the electrolytic plating, the metal portion protected by the masking tape as described above is also charged, so that the corrosion easily proceeds.

If the degree of absorption of the plating solution into the adhesive is too great, even the protected portion protected by the masking tape is plated, causing a disturbance in the plating line.

[0012] An object of the present invention is to prevent the metal of the protected portion from corroding and to use the adhesive between the metal material and the masking tape despite the use of a water-soluble or water-dispersible adhesive. An object of the present invention is to provide a masking tape which has good masking performance and does not cause disturbance of a plating line even if a plating solution permeates.

[0013]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that if a benzotriazole compound is contained in an adhesive, the above object can be attained. The present invention has been made. That is,
The present invention is a masking tape used for protecting a non-plated portion from a plating solution when plating metal, having a base material and an adhesive layer formed on one surface of the base material, A masking tape in which the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is water-soluble or water-dispersible and contains a benzotriazole-based compound.

Hereinafter, the present invention will be described in detail. The masking tape of the present invention is characterized in that the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer formed on one surface of the substrate contains a benzotriazole-based compound as described above. Benzotriazole-based compounds that can be used include benzotriazole, methylbenzotriazole, their alkali metal salts, derivatives and mixtures thereof, and the like.

The benzotriazole-based compound can be contained in the pressure-sensitive adhesive by an appropriate method. For example, in the case of a pressure-sensitive adhesive tape manufacturing method in which a pressure-sensitive adhesive composition comprising an acrylic monomer or a prepolymer is applied to a substrate, and then the pressure-sensitive adhesive tape is formed by photopolymerization to form a pressure-sensitive adhesive layer, Alternatively, the benzotriazole-based compound may be blended in the prepolymer. When the method is applied to a method of polymerizing a pressure-sensitive adhesive polymer by thermally polymerizing a monomer, it is preferable to dissolve the above-mentioned benzotriazole-based compound in the monomer and mix it sufficiently uniformly before polymerizing.

When the pressure-sensitive adhesive is a solvent-type pressure-sensitive adhesive, it is preferable to dilute the benzotriazole compound in an appropriate solvent and mix it with the pressure-sensitive adhesive. Furthermore, when the pressure-sensitive adhesive is an aqueous dispersion or an aqueous system, a method in which the benzotriazole-based compound is dissolved and mixed in a solvent compatible with water such as alcohol, or an alkali metal salt of the benzotriazole-based compound is used. The method of mixing with the above-mentioned aqueous dispersion or aqueous adhesive is suitable.

In any case, the method of incorporating the benzotriazole-based compound into the pressure-sensitive adhesive is not particularly limited, and may be appropriately selected depending on the kind of the pressure-sensitive adhesive to be used. When the compound is mixed with the pressure-sensitive adhesive, it is preferable to uniformly mix the compound in order to sufficiently exert the effect.

The benzotriazole-based compound acts to form a protective film on the metal material to be protected, and is used in an amount of 0.01 to 3 parts by weight based on 100 parts by weight of the adhesive. , More preferably 0.1 to 1 part by weight.

If the amount is less than 0.01 parts by weight, the oxidation of the metal material due to the water absorption phenomenon of the pressure-sensitive adhesive cannot be sufficiently prevented, and the corrosion of the protected portion cannot be reliably prevented. On the other hand, if the amount exceeds 3 parts by weight, adhesive properties such as adhesive strength may be reduced, and plating may be insufficient at a plated portion near the edge of the masking tape. This is considered to be because the benzotriazole-based compound released from the adhesive forms a protective film on the metal material portion to be plated near the masked portion. In any case, the amount of the benzotriazole-based compound should be optimally selected depending on the plating time, the type of metal to be plated, the adhesive properties of the adhesive, and the like, and cannot be determined uniquely.

As the water-soluble or water-dispersible pressure-sensitive adhesive used in the masking tape of the present invention, an alkali water-soluble pressure-sensitive adhesive obtained by copolymerizing a specific carboxyl group-containing monomer and an alkyl acrylate at a specific ratio (Japanese Patent Application No. Hei. -303582) and those obtained by blending diethylene glycol with polyacrylic acid (Japanese Patent Application Laid-Open No. 60-229772).
A mixture of polyethyleneimine and aminated starch and polyacrylic acid (Japanese Patent Publication No. 52-32769) can be used. Also, natural products such as polysaccharides, cellulose, starch, and proteins, semi-synthetic natural products such as carboxylated cellulose and carboxylated starch, sodium polyacrylate, acrylic copolymer, polyethyleneimine, poval, polyvinylpyrrolidone, and polyalkyl Those based on a water-soluble resin such as a synthetic polymer such as oxazoline can also be used.

The masking tape of the present invention is characterized by including a benzotriazole-based compound in a water-dispersible or water-soluble adhesive as described above,
In other respects, for example, the type of the base material and the method for producing the pressure-sensitive adhesive tape are not particularly limited as long as the object of the present invention can be achieved. However, when a plastic film such as polyester, polyethylene, polypropylene, polyamide, polystyrene, polyvinyl acetate, polyvinyl chloride, and polyvinylidene chloride is used as the base material, a masking tape satisfying both strength and water resistance can be obtained. it can.

Further, in the above-mentioned adhesive, in addition to the benzotriazole compound, an antioxidant, an antioxidant, a stabilizer, a crosslinking agent, a plasticizer, a tackifier, a neutralizer, a filler,
A foaming agent, an antifoaming agent and the like may be appropriately compounded within a range that does not impair the purpose of the present invention.

[0023]

According to the present invention, since the benzotriazole compound is mixed in the water-soluble or water-dispersible pressure-sensitive adhesive, the benzotriazole compound forms a protective film on the surface of the protected part. Corrosion of metal can be reliably prevented. Furthermore, even if the plating solution infiltrates the interface between the protected part and the masking tape, the metal agent surface is plated on the protected part probably because the benzotriazole-based compound forms a protective film on the surface of the protected part. Is also reliably prevented.

[0024]

The present invention will be clarified below by describing non-limiting examples of the present invention. In the following, parts mean parts by weight unless otherwise specified. Preparation of adhesive 12.5 parts of acrylic acid 87.5 parts of butyl acrylate 100 parts of ethyl acetate

The composition having the above composition was charged into a separable flask and stirred at 60 ° C. under a nitrogen atmosphere.
Was heated. Next, 0.03 parts of azobisisobutyronitrile as a thermal decomposition initiator was added to 100 parts of the total of the above monomer components, and then polymerized for 8 hours to obtain a base polymer having a weight average molecular weight of 500,000. . An acetylacetone-aluminum complex was blended with this base polymer so that the final degree of crosslinking was 80% to prepare a pressure-sensitive adhesive.

Examples 1 to 6 and Comparative Examples 1 to 4 For 100 parts of the adhesive prepared as described above,
Benzotriazole, methylbenzotriazole, octadecyl-3- (3 ', 5'-di-t-butyl-4'-
(Hydroxyphenyl) propionate and 4,4'-
At least one kind of bis- (α, α-dimethyl-benzyl) diphenylamine is blended in a ratio shown in Table 1 below,
38 which was sufficiently homogeneously mixed and then treated with corona discharge
A masking tape was prepared by coating and drying one surface of a substrate made of polyethylene terephthalate having a thickness of μm to a thickness of 80 μm. Further, only the adhesive prepared as described above was similarly coated and dried to obtain a base tape.

Evaluation (Test 1) A test plate A was prepared in which a copper foil 2 having a thickness of 20 μm was laminated on one surface of a glass epoxy plate 1 shown in FIG. A masking tape was thermocompression-bonded on this test plate A at 120 ° C., and then immersed in a 0.5N sulfuric acid aqueous solution at 60 ° C. for 60 minutes or 120 minutes, and then Ni plating was applied for 1 minute. Next, after washing the plating solution with tap water, the masking tape was peeled off, and the presence or absence of discoloration of the protected portion covered with the masking tape was observed. The results are shown in Table 2 below.

(Test 2) As shown in FIG. 2, strip-shaped copper pieces 3 having a thickness of 50 μm and a width of 1 mm were placed in parallel on the surface of the test plate A on the side of the copper foil 2 at an interval of 1 mm. Affix,
Test plate B was used. Next, as shown in FIG. 3, after covering a part of the copper piece 3 and applying a masking tape with a 2 kg rubber roller at an application speed of 300 mm / min so as to expose the remaining part, shown in FIG. 4. Thus, the test plate B was immersed in the Ni plating solution 5 so as to be immersed up to the intermediate height position of the masking tape 4, and Ni plating was applied for 1 minute. After plating, it is taken out of the Ni plating solution 5 and, as shown in FIG.
The masking tape 4 was peeled off, and the edge of the plating portion 6 (the portion shown by hatching in FIG. 5), that is, the state of the plating line 6a was observed. FIG. 6 shows a state in which the masking tape 4 has been peeled off. The results are shown in Table 2 below.

[0029]

[Table 1]

In Table 1, the contents of the compositions No. 1 to No. 4 are as follows. No. 1: benzotriazole No. 2: methyl benzotriazole No. 3: octadecyl-3- (3 ', 5'-di-t-butyl-4'-hydroxyphenylpropionate No.4: 4,4'- Bis (α, α-dimethyl-benzyl) diphenylamine

[0031]

[Table 2]

As is clear from Table 2, in the masking tapes of Comparative Examples 1 to 4, discoloration was observed in the protected portion in Test 1, and in the Test 2 using Test Plate B, the plating line was curved. I was Similarly, in the base tape, discoloration of the protected portion and meandering of the plating line were observed.

On the other hand, in Examples 1 to 6, there is no discoloration of the protected portion or only slight discoloration, and the shape of the plating line is slightly disturbed (Example Although there was 1), there was no disturbance in most cases (Examples 2 to 6).

Accordingly, the above Examples 1 to 6 and Comparative Example 1
According to the present invention, it is possible to provide a masking tape having a good masking performance capable of preventing oxidation of a copper surface and disturbance of a plating line, as is apparent from the results of Tests 1 and 2 and base tapes 1 and 2. You can see that.

[0035]

According to the present invention, since a benzotriazole-based compound is contained in the pressure-sensitive adhesive, even if a water-soluble or water-dispersible pressure-sensitive adhesive is used, the pressure-sensitive adhesive is not affected by the water contained therein. It is possible to reliably prevent corrosion of the metal of the protection portion, and to obtain a masking tape excellent in masking performance that does not cause disturbance in the shape of the plating line.

Accordingly, it is possible to provide a masking tape which is suitable for a field where de-fluorocarbon and solvent removal treatment is required, such as a printed circuit board, and has excellent masking performance.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a test plate A used in Test 1.

FIG. 2 is a perspective view showing a test plate B used in Test 2.

FIG. 3 is a perspective view showing a state in which a masking tape is attached to a test plate B.

FIG. 4 shows a test plate B to which a masking tape is stuck.
FIG. 4 is a schematic perspective view for explaining a step of plating a substrate.

FIG. 5 is a plan view showing a step of peeling a masking tape from a test plate B.

FIG. 6 is a perspective view showing a test plate B from which a masking tape has been peeled off.

[Brief description of reference numerals]

 A, B: Test plate 2: Copper foil 3: Copper piece 4: Masking tape

Claims (1)

(57) [Claims] Claims: 1. A masking tape used for protecting a non-plated portion from a plating solution when plating a metal, comprising: a base material; and an adhesive layer formed on one surface of the base material. A masking tape, wherein the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is water-soluble or water-dispersible and contains a benzotriazole-based compound.