JP5503129B2 - Masking tape and manufacturing method thereof - Google Patents

Description

  The present invention relates to a masking tape and a method for producing the same, and more specifically, there is no adhesive residue at the initial stage of application, no cleaning is required, and when the masking tape is applied and stored for a certain period of time, the portion where the tape is applied becomes cloudy. In particular, the present invention relates to a masking tape suitable for masking (surface protection) when plating the same or different metal on a metal surface, which can be further stably plated, and a method for producing the same.

  Conventional methods have been widely used to impart new performance to the original metal material and to protect the metal material surface from oxidation or abrasion by plating (coating) the surface of the metal material with the same or different metal. ing. As one of such methods, there is an electrolytic plating method. In the electroplating method, an acidic or alkaline metal electrolyte aqueous solution is used as a plating solution, and by adding an electric charge to the portion to be plated, the metal in the plating solution is deposited on the metal surface, thereby forming a plating film.

  By the way, in electrolytic plating, a masking tape is applied to the non-plated portion in order to protect the non-plated portion so that the non-plated portion is not plated or to make the plated portion have a desired shape. There is.

  The plating masking tape has excellent sharpness of the plating line (the contour of the plating part, that is, the boundary line between the plating part and the non-plating part), and may cause adhesive residue on the pasting surface after use. And that it can be easily peeled off again and that the adhesive does not contaminate the plating solution.

  As a tape that has no adhesive residue and can be easily removed, for example, in Patent Document 1, “A-B-A” (where A is a styrene polymer block, and B is a copolymer block of ethylene and butylene). ) "Surface protective adhesive film formed by forming an adhesive layer made of a composition containing 100 parts by weight and tackifying resin 0 to 80 parts by weight on a polyolefin resin film (substrate)" is disclosed. .

  However, when the surface protective film disclosed in the above disclosure is used as a masking tape, the plating solution is easily absorbed into the adhesive layer, and thus even non-plated parts protected by the masking tape tend to be plated. There is a problem that the sharpness of the plating line becomes poor.

  In addition, as an example of a masking tape for plating, Patent Document 2 states that “a masking tape used for protecting a portion that is not subjected to plating when plating a metal from a plating solution. A masking tape having a pressure-sensitive adhesive layer formed thereon, wherein the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is water-soluble or water-dispersible and contains a benzotriazole compound. It is disclosed.

  However, in the case of the masking tape disclosed above, although the sharpness of the plating line is good, a water-soluble or water-dispersible adhesive is used, which tends to cause adhesive residue on the pasted surface after peeling. As a result, there is a problem that the adhesive residue needs to be washed with water.

In order to solve the above-mentioned conventional problems, the present applicant previously described in Patent Document 3 has good tack and adhesive strength, and the plating solution is difficult to penetrate into the adhesive layer. Has proposed a masking tape for plating that is excellent in sharpness, is easy to re-peel after use and does not cause adhesive residue on the pasted surface, and therefore does not require cleaning.
However, in this case, it is now possible to provide a plating masking tape that has no adhesive residue and does not require cleaning at the beginning of application, but if the masking tape is applied to the lead frame in advance and stored for a certain period of time, it will be transferred from the masking tape. Due to the components, the portion where the tape was applied was clouded, and it was confirmed that the formation of the plating layer would become unstable if further plating was performed thereon.

JP 61-103975 A Japanese Patent No. 2806728 JP 2000-319606 A

  The object of the present invention is to solve the above-mentioned problems of the prior art, there is no adhesive residue at the initial stage of application, no cleaning is required, and when the masking tape is applied and stored for a certain period of time, the tape-applied part is not cloudy. Another object of the present invention is to provide a masking tape suitable for masking (surface protection) when plating the same or different kinds of metal on a metal surface, and a method for producing the same. .

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has, as a result, a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive containing a specific resin and low molecular weight polyethylene as an antiblocking agent on one surface of a polyolefin-based resin base material. With the masking tape formed, there is no adhesive residue at the beginning of application and no cleaning is required. And when the masking tape is stored for a certain period of time with the masking tape applied, the part where the tape is applied is not fogged, and the plating is further plated thereon. Has been found to be stably applied, and the present invention has been completed.

That is, according to the first invention of the present invention, a masking tape having an adhesive layer formed on one side of a polyolefin resin substrate,
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is composed of an elastomer hydrogenated resin composed of a styrene compound polymer block and a styrene-conjugated diene random copolymer block and / or a hydrogenated resin of a styrene-conjugated diene-styrene block copolymer. In addition to 0 to 40 parts by weight of α-methylstyrene resin, 0 to 40 parts by weight of tackifier resin, and 0.1 to 2 parts by weight of benzotriazole compound with respect to 100 parts by weight of the selected hydrogenated styrene elastomer, It consists of a resin composition containing a low molecular weight polyethylene having a number average molecular weight of 10,000 or less at 0.05 to 2.0% by weight based on the total amount as an antiblocking agent,
When the hydrogenated styrene-based elastomer contains calcium stearate, the calcium stearate is removed by washing in advance, and a masking tape used for plating is provided.

According to a second aspect of the present invention, there is provided the masking tape according to the first aspect , wherein the low molecular weight polyethylene is a powder having an average particle diameter of 3 to 50 μm.

According to the third aspect of the present invention, an elastomeric hydrogenated resin and / or styrene-conjugated diene comprising a styrene compound polymer block and a styrene-conjugated diene random copolymer block is provided on one side of a polyolefin resin substrate. -0 to 40 parts by weight of an α-methylstyrene resin, 0 to 40 parts by weight of a tackifying resin and a benzotriazole compound with respect to 100 parts by weight of a hydrogenated styrene elastomer selected from hydrogenated resins of styrene block copolymers In addition to 0.1 to 2 parts by weight, a pressure-sensitive adhesive layer comprising a resin composition in which a low molecular weight polyethylene having a number average molecular weight of 10,000 or less and 0.05 to 2.0% by weight based on the total amount is further added as an antiblocking agent. the first or masking tape manufacturing method of the second invention, characterized in that the formation by a co-extrusion method is Hisage It is.

  The masking tape according to the present invention has an elastomer hydrogenated resin and / or styrene-conjugated diene-styrene comprising a styrene compound polymer block and a styrene-conjugated diene random copolymer block as the main component of the adhesive constituting the adhesive layer. Since a hydrogenated resin of a block copolymer (hereinafter referred to as hydrogenated styrene elastomer) is used, the balance between tack, adhesive force, cohesive force and elastic modulus is excellent. Therefore, the adhesiveness to the adherend is good, the re-peelability after use is excellent, and no adhesive residue is generated on the adhesive surface, so that cleaning is not necessary.

  Moreover, the above-mentioned performance is further improved by adding an α-methylstyrene-based resin or tackifying resin having a specific amount or less to a specific amount of the hydrogenated styrene-based elastomer.

  Furthermore, the masking tape according to the present invention uses a pressure-sensitive adhesive to which a specific amount of benzotriazole-based compound is added as a pressure-sensitive adhesive layer with respect to a specific amount of the hydrogenated styrene-based elastomer. Is difficult to permeate, and therefore the plating line is clear.

In addition, by using low molecular weight polyethylene as an anti-blocking agent, there is no adhesive residue at the beginning of application, no cleaning is required, and when the masking tape is applied and stored for a certain period of time, the taped part is not cloudy. Further, the plating can be further stably applied, and the stability over time is also improved.
Therefore, the masking tape of the present invention is suitable mainly for masking (surface protection) when the same or different metal is plated on the metal surface.

Hereinafter, the masking tape of the present invention and the manufacturing method thereof will be described in detail.
1. Masking tape base material The polyolefin resin constituting the base material of the masking tape according to the present invention is not particularly limited, and examples thereof include low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene. Polypropylene, propylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl (meth) acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-n-butyl acrylate copolymer, etc. And preferably used. These polyolefin resin may be used independently and 2 or more types may be used together.

  Although the manufacturing method of a base material is not specifically limited, Generally, it is preferable to film-form the said polyolefin resin by the melt-extrusion method, and to use as a base material.

2. Adhesive The adhesive constituting the adhesive layer of the masking tape according to the present invention comprises an elastomer hydrogenated resin comprising a styrene compound polymer block and a styrene-conjugated diene random copolymer block and / or a styrene-conjugated diene-styrene block copolymer. Blocking in addition to 0 to 40 parts by weight of α-methylstyrene resin, 0 to 40 parts by weight of tackifier resin, and 0.1 to 2 parts by weight of benzotriazole compound with respect to 100 parts by weight of the hydrogenated resin of the polymer. It consists of the resin composition which mix | blended 0.05-2.0 weight% low molecular weight polyethylene on the basis of whole quantity as an inhibitor.

(1) Hydrogenated Styrenic Elastomer An elastomer hydrogenated resin comprising a styrene compound polymer block and a styrene-conjugated diene random copolymer block that can be used as the main component of the pressure-sensitive adhesive is represented by the general formula XYZ. It is a resin in which the double bond of the conjugated diene moiety in the elastomer comprising the styrene compound polymer block and the styrene-conjugated diene random copolymer block is hydrogenated.

  In the above formula, X represents a styrene compound polymer block, Y represents a styrene-conjugated diene random copolymer block, Z represents a styrene-conjugated diene random copolymer block, and the copolymerization ratio of styrene is higher than that of Y. A large tapered block is shown.

  The styrenic compound is not particularly limited, and examples thereof include styrene, α-methylstyrene, vinyltoluene, 1,1-diphenylethylene, and the like. Among them, styrene and α- Methyl styrene is more preferably used. These styrene compounds may be used alone or in combination of two or more.

  The conjugated diene is a hydrocarbon having a structure (C═C—C═C) in which two ethylene bonds are directly bonded by a single bond, and is not particularly limited. Isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene and the like can be mentioned, and preferably used. Among them, butadiene and isoprene are more preferably used. These conjugated dienes may be used alone or in combination of two or more.

  The ratio of the styrene compound to the conjugated diene is not particularly limited in the total monomer constituting the elastomer composed of the styrene compound polymerization block and the styrene-conjugated diene random copolymer block, but the weight ratio is styrene. The compound / conjugated diene is preferably 5/95 to 60/40, more preferably 7/93 to 40/60.

  If the styrene-based compound / conjugated diene is less than 5/95 (weight ratio), the cohesive force of the resulting adhesive will decrease, and adhesive residue may occur on the application surface when the masking tape is peeled off again. If the styrene compound / conjugated diene exceeds 60/40 (weight ratio), the tackiness and adhesive strength of the resulting pressure-sensitive adhesive will decrease, and it may be difficult to apply the masking tape to the adherend.

  The bond content of the styrene compound polymer block in the elastomer composed of the styrene compound polymer block and the styrene-conjugated diene random copolymer block is preferably 3% by weight or more, more preferably 3 to 20% by weight, In addition, the content of the styrene compound in the elastomer composed of the styrene compound polymer block and the styrene-conjugated diene random copolymer block is preferably 3 to 50% by weight, more preferably 5 to 40% by weight of the total monomers. %, Particularly preferably 5 to 25% by weight.

  If the styrene-based compound bond content is less than 3% by weight of the total monomer, the cohesive strength of the resulting adhesive will decrease, and adhesive residue may occur on the adhesive surface when the masking tape is peeled off again. In addition, when the bond content of the styrene compound exceeds 50% by weight of the total monomer, the tackiness and adhesive strength of the resulting pressure-sensitive adhesive are reduced, and it may be difficult to apply the masking tape to the adherend.

  The vinyl bond content of the conjugated diene moiety in the styrene-conjugated diene random copolymer block is preferably more than 60% by weight, more preferably 70% by weight or more, and particularly preferably 80% by weight or more. . The vinyl bond referred to here means a monomer unit obtained by polymerizing a conjugated diene compound with a double bond at a 1,2- or 3,4-bond position.

  When the vinyl bond content of the conjugated diene moiety is 60% by weight or less, the tackiness and adhesive strength of the resulting pressure-sensitive adhesive may be insufficient.

  The hydrogenation rate of the double bond of the conjugated diene moiety in the styrene-conjugated diene random copolymer block is preferably 80 mol% or more, more preferably 90 mol% or more, particularly preferably 95 to 100 mol. % Saturated state.

  When the hydrogenation rate of the double bond of the conjugated diene moiety is less than 80 mol%, the resulting adhesive may have poor thermal stability and weather resistance.

  The elastomer hydrogenated resin composed of a styrene compound polymer block and a styrene-conjugated diene random copolymer block preferably has a polystyrene equivalent weight average molecular weight of 50,000 to 400,000, more preferably 80,000 to 200,000. is there.

  If the weight-average molecular weight of the elastomeric hydrogenated resin composed of the styrene compound polymer block and the styrene-conjugated diene random copolymer block is less than 50,000, the cohesive force of the resulting pressure-sensitive adhesive decreases, so the masking tape must be reused. Adhesive residue may be generated on the application surface when peeling, and conversely, if the weight average molecular weight exceeds 400,000, the tack and adhesive strength of the resulting adhesive will decrease, so the masking tape may be applied to the adherend. It can be difficult.

  The elastomeric hydrogenated resin comprising the styrene compound polymer block and the styrene-conjugated diene random copolymer block described above may be used alone or in combination of two or more.

  Next, the hydrogenated resin of the styrene-conjugated diene-styrene block copolymer that can be used as the main component of the pressure-sensitive adhesive is not particularly limited. For example, in the styrene-butadiene-styrene block copolymer The double bond of the isoprene moiety in the styrene-ethylene-butylene-styrene block copolymer (SEBS) and the styrene-isoprene-styrene block copolymer obtained by hydrogenating the double bond of the butadiene part of Styrene-ethylene-propylene-styrene block copolymer (SEPS) obtained by the above method is preferably used.

  The bonding form of the styrene-conjugated diene-styrene block copolymer may be any form such as a diblock type, a triblock type, a tapered block type, and a linear multiblock type, and these are mixed. Form may be sufficient.

  The hydrogenation rate of the double bond of the conjugated diene moiety in the styrene-conjugated diene-styrene block copolymer is the case of an elastomer hydrogenated resin comprising the styrene compound polymer block and the styrene-conjugated diene random copolymer block. For the same reason, it is preferably 80 mol% or more, more preferably 90 mol% or more, and particularly preferably 95 to 100 mol% in a saturated state.

  The styrene-conjugated diene-styrene block copolymer hydrogenated resin is converted into polystyrene for the same reason as in the case of the elastomer hydrogenated resin composed of the styrene compound polymer block and the styrene-conjugated diene random copolymer block. The weight average molecular weight is preferably 50,000 to 400,000, more preferably 80,000 to 200,000.

  The hydrogenated resin of the styrene-conjugated diene-styrene block copolymer described above may be used alone or in combination of two or more.

  In addition, the hydrogenated resin of the elastomer composed of the styrene compound polymer block and the styrene-conjugated diene random copolymer block and the hydrogenated resin of the styrene-conjugated diene-styrene block copolymer may be used alone. And both may be used together.

(2) α-methylstyrene-based resin In the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer of the masking tape according to the present invention, an elastomer composed of the above-mentioned styrene-based compound polymer block and styrene-conjugated diene random copolymer block as the main components is used. 0 to 40 parts by weight of α-methylstyrene resin with respect to 100 parts by weight of hydrogenated resin and / or hydrogenated resin of styrene-conjugated diene-styrene block copolymer (hereinafter referred to as “hydrogenated styrene elastomer”) Is added.

  The α-methylstyrene-based resin is not particularly limited, and examples thereof include a homopolymer of α-methylstyrene and a copolymer of α-methylstyrene and terpenes, and the like. Used for.

  The α-methylstyrene-based resin may be used alone or in combination of two or more.

  Since the α-methylstyrene resin exhibits a function of reinforcing the styrene portion in the hydrogenated styrene elastomer, the elastic modulus of the obtained adhesive is further improved. As a result, the removability of the masking tape, particularly the removability when peeling at a high speed, becomes more excellent, and it is possible to more effectively prevent the adhesive residue on the application surface.

  In the pressure-sensitive adhesive used in the present invention, the α-methylstyrene resin may not necessarily be added, but it is 40 parts by weight or less, preferably 1 to 40 parts by weight with respect to 100 parts by weight of the hydrogenated styrene elastomer. By adding the α-methylstyrene-based resin, the above adhesive residue preventing effect can be obtained without impairing tack and adhesive strength.

  If the amount of α-methylstyrene resin added to 100 parts by weight of the hydrogenated styrene elastomer exceeds 40 parts by weight, the resulting adhesive will have an excessively high elastic modulus, resulting in insufficient tack and adhesive strength.

(3) Tackifying resin In the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer of the masking tape according to the present invention, 0 to 40 parts by weight of the tackifying resin is added to 100 parts by weight of the hydrogenated styrene elastomer as the main component. Is done.

  The tackifying resin is not particularly limited, and examples thereof include rosin resins, terpene resins, terpene phenol resins, aliphatic petroleum resins, alicyclic petroleum resins, and aromatic petroleum resins. And coumarone indene-based resins, and the like.

  The tackifying resin may be used alone or in combination of two or more.

  In the pressure-sensitive adhesive used in the present invention, the tackifying resin does not necessarily have to be added, but it is 40 parts by weight or less, preferably 5 to 40 parts by weight based on 100 parts by weight of the hydrogenated styrene elastomer. By adding a property imparting resin, tack and adhesive strength can be effectively improved without impairing removability.

  If the addition amount of the tackifying resin with respect to 100 parts by weight of the hydrogenated styrene elastomer exceeds 40 parts by weight, the tack and adhesive strength of the resulting adhesive become too strong, the removability is reduced, and the adhesive surface has a paste. The rest occurs.

(4) Benzotriazole-based compound In the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer of the masking tape according to the present invention, 0.1 to 2 parts by weight of the benzotriazole-based compound with respect to 100 parts by weight of the hydrogenated styrene elastomer as the main component. Must be added.

  Although it does not specifically limit as said benzotriazole type compound, For example, benzotriazole, methylbenzotriazole, or these alkali metal salts, derivatives, or a mixture etc. are mentioned, It uses suitably.

  The said benzotriazole type compound may be used independently and 2 or more types may be used together.

  Part or all of the benzotriazole-based compound is released from the pressure-sensitive adhesive layer and exhibits a function of forming a protective film on the metal material of the protected portion (non-plated portion). Therefore, by adding the benzotriazole-based compound into the pressure-sensitive adhesive, it is possible to effectively prevent the plating solution from penetrating into the pressure-sensitive adhesive layer, and a clearer plating line can be obtained.

  If the amount of the benzotriazole compound added relative to 100 parts by weight of the hydrogenated styrene elastomer is less than 0.1 parts by weight, the effect of clarifying the plating line cannot be sufficiently obtained. When the amount exceeds 2 parts by weight, the benzotriazole-based compound itself exudes from the boundary line between the portion to be plated and the non-plated portion, and the sharpness of the plating line is deteriorated.

(5) Low molecular weight polyethylene The masking tape of the present invention has a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive containing the above-described resin component and low-molecular weight polyethylene as an anti-blocking agent (hereinafter also referred to as “external lubricant”). It is necessary to be made.
When low molecular weight polyethylene is not used as an anti-blocking agent, if the masking tape is previously applied to the lead frame and stored for a certain period of time, the part where the tape is applied becomes cloudy due to the migration component from the masking tape, and plating is further applied thereon. When applied, the formation of the plating layer tends to become unstable.
As a result of intensive studies to solve the above problems, the present inventor has found that the main component of the lipcus is a metal soap such as calcium stearate used as an antiblocking agent. And it discovered that lip stain | pollution | contamination was reduced by adding low molecular weight polyethylene as an antiblocking agent changed to calcium stearate.

  The low molecular weight polyethylene used in the present invention is preferably powdery at room temperature. The average particle diameter of the low molecular weight polyethylene is preferably 3 to 50 μm, particularly preferably 3 to 20 μm. When the average particle size is 3 μm or less, the handleability is deteriorated because it is too small, and when it is 50 μm or more, the effect as a blocking inhibitor may not be sufficiently exhibited because it is too large to be uniformly dispersed. Here, the average particle diameter is defined as a median system (medium system) in a cumulative distribution of particle diameters measured by a laser diffraction / scattering method.

  The molecular weight of the low molecular weight polyethylene used as the antiblocking agent is not particularly limited, but a number average molecular weight in the range of 10,000 or less is preferable from the viewpoint of compatibility.

  A preferable addition amount of the low molecular weight polyethylene is 0.05 to 2.0% by weight based on the total amount of the pressure-sensitive adhesive. When the addition amount is less than 0.05% by weight, sufficient anti-blocking performance may not be exhibited. If the amount added exceeds 2.0% by weight, the physical properties of the adhesive may be adversely affected.

  In addition, hydrogenated styrene elastomers made from commercially available raw materials may be added with an anti-blocking agent other than low molecular weight polyethylene, such as calcium stearate and ethylene bis (stearylamide) (EBSA). As described above, antiblocking agents other than these low molecular weight polyethylenes are considered to cause lip stains. Therefore, when adding low molecular weight polyethylene, it is necessary to use a hydrogenated styrene elastomer washed as a hydrogenated styrene elastomer. An example of washing is washing with water. It is preferable to use a hydrogenated styrene elastomer that has been washed with water and then air-dried.

  Examples of the method of externally adding an antiblocking agent to the adhesive include dry blending using a turbula shaker mixer, a Henschel mixer, a ribbon blender, a spar mixer, a V blender, and the like.

  In addition to the above-mentioned components, the pressure-sensitive adhesive used in the present invention includes, as necessary, a filler, a softener, a plasticizer, a surfactant, a coupling agent, an oxidizing agent within a range that does not hinder achievement of the problems of the present invention. One kind or two or more kinds of various additives such as an inhibitor, an anti-aging agent, a stabilizer, an ultraviolet absorber, a crosslinking agent, and a colorant may be added.

4). Masking Tape Manufacturing Method The masking tape manufacturing method according to the present invention employs, for example, a co-extrusion method, and simultaneously extrudes the polyolefin resin for the substrate and the adhesive for the adhesive layer to mask at once. A tape may be manufactured, and a polyolefin resin base material, a solvent-type adhesive in which an adhesive is dissolved in an organic solvent, and an emulsion-type adhesive in which an adhesive is emulsified and dispersed in water are prepared in advance. A masking tape may be manufactured by applying a pressure-sensitive adhesive on one side of a polyolefin resin substrate by a solution coating method, an emulsion coating method, a hot melt coating method, etc., but a co-extrusion method with excellent productivity is adopted. It is preferable.

  In the masking tape according to the present invention, the thickness of the substrate is not particularly limited, but is preferably 300 μm or less, and more preferably 10 to 100 μm. The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 200 μm or less, more preferably 5 to 50 μm.

  The masking tape according to the present invention thus obtained is mainly used for plating, but of course may be used for other purposes.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples. The evaluation methods used in the examples are as follows.

1. Evaluation Method (1) Plating Evaluation A masking tape was attached to a copper plate and immersed in an aqueous sulfuric acid solution (0.5N) at 60 ° C. for 1 hour, and then subjected to silver plating for 1 minute. Next, after washing the silver plating solution with tap water, the masking tape was peeled off again, and the sharpness of the plating line and the presence or absence of discoloration were visually observed.
In addition, a masking tape applied to a copper plate and held for 14 days in a 40 ° C. environment was similarly immersed in a 60 ° C. sulfuric acid aqueous solution (0.5 N) for 1 hour, and then subjected to silver plating for 1 minute. . Next, after the silver plating solution was washed with tap water, the masking tape was peeled off again, and the sharpness (parting performance) of the plating line and the presence or absence of discoloration (cloudiness) were visually observed.
(2) Adhesive strength evaluation According to JIS Z-0237 “Testing method for adhesive tape and adhesive sheet”, 180 degree angle peel adhesive strength (g) for SUS (stainless steel) surface, copper surface and silver surface of masking tape / 25 mm).
(3) Comprehensive evaluation After aging for 14 days in a 40 ° C environment with masking tape applied, the evaluation regarding the sharpness and discoloration of the plating line was good, and the evaluation was poor. △, what was bad as a whole was set as x.

2. Example 1 and Comparative Examples 1-3
Example 1
As a base material, polyolefin resin by mixing 75 parts by weight of block type polypropylene (trade name “BC3M”, manufactured by Tonen Chemical Co., Ltd.) and 25 parts by weight of low density polyethylene (trade name “Mirason 12”, manufactured by Mitsui Chemicals, Inc.) A composition was prepared. Also, for the adhesive layer, an elastomer hydrogenated resin (trade name “Dynalon 1321P”, manufactured by JSR Corporation) consisting of a styrene compound polymer block and a styrene-conjugated diene random copolymer block was once washed with water and then air-dried. 100 parts by weight of a product, 20 parts by weight of a tackifying resin (trade name “Alcon P100”, manufactured by Arakawa Chemical Co., Ltd.), 10 parts by weight of α-methylstyrene resin (trade name “Endex 155”, manufactured by Rika Hercules) A pressure-sensitive adhesive was prepared by mixing 0.5 parts by weight of methylbenzotriazole and subsequently ACumist C20 (powdered polyethylene).

  Next, using the polyolefin-based resin composition for the base material and the pressure-sensitive adhesive resin composition for the pressure-sensitive adhesive layer obtained above, the thickness of the base material is 35 μm and the thickness of the pressure-sensitive adhesive layer is 5 μm by the coextrusion method. A masking tape was prepared.

(Comparative Example 1)
A masking tape was prepared in the same manner as in Example 1 except that the hydrogenated styrene elastomer was not washed.

(Comparative Example 2)
A masking tape was prepared in the same manner as in Example 1 except that calcium stearate was used as an antiblocking agent and the hydrogenated styrene elastomer was not washed.

(Comparative Example 3)
A masking tape was prepared in the same manner as in Example 1 except that EBSA (ethylenebis (stearylamide)) was used as an antiblocking agent and the hydrogenated styrene elastomer was not washed.

  These masking tapes were evaluated. Any of the masking tapes of Example 1 and Comparative Examples 1 to 3 showed good adhesive strength to any of the SUS surface, the copper surface, and the silver surface. The results of plating evaluation and comprehensive evaluation were as shown in Table 1.

  As is clear from Table 1, the masking tapes of the examples according to the present invention were excellent in sharpness without any discoloration of the plating line even after aging.

  On the other hand, the masking tape of the comparative example using an adhesive that did not contain low molecular weight polyethylene as an antiblocking agent as the adhesive layer showed discoloration in the plating line after the lapse of time, and the sharpness was poor.

As described above, the masking tape according to the present invention has good tack and various adherends, and the plating solution is difficult to penetrate into the adhesive layer, so that the plating line is clear. It is excellent and has excellent re-peelability and does not cause any adhesive residue on the sticking surface, so cleaning is unnecessary. Moreover, it is excellent in stability over time. Therefore, it is suitably used as a masking tape for plating.

Claims (3)

A masking tape in which an adhesive layer is formed on one side of a polyolefin resin substrate,
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is composed of an elastomer hydrogenated resin composed of a styrene compound polymer block and a styrene-conjugated diene random copolymer block and / or a hydrogenated resin of a styrene-conjugated diene-styrene block copolymer. In addition to 0 to 40 parts by weight of α-methylstyrene resin, 0 to 40 parts by weight of tackifier resin, and 0.1 to 2 parts by weight of benzotriazole compound with respect to 100 parts by weight of the selected hydrogenated styrene elastomer, It consists of a resin composition containing a low molecular weight polyethylene having a number average molecular weight of 10,000 or less at 0.05 to 2.0% by weight based on the total amount as an antiblocking agent,
When the hydrogenated styrene-based elastomer contains calcium stearate, the calcium stearate is previously washed to remove the calcium stearate , and used for plating . The masking tape according to claim 1 , wherein the low molecular weight polyethylene is a powder having an average particle diameter of 3 to 50 μm. One side of the polyolefin resin substrate is selected from an elastomer hydrogenated resin composed of a styrene compound polymer block and a styrene-conjugated diene random copolymer block and / or a hydrogenated resin of a styrene-conjugated diene-styrene block copolymer. In addition to 0 to 40 parts by weight of α-methylstyrene resin, 0 to 40 parts by weight of tackifier resin, and 0.1 to 2 parts by weight of benzotriazole compound with respect to 100 parts by weight of hydrogenated styrene elastomer, further blocking prevention an adhesive layer made of the resin composition blended with a number average molecular weight of 10,000 or lower molecular weight polyethylene with 0.05 to 2 wt% based on the total quantity as agents, or claim 1, characterized in that to form a co-extrusion 2. A method for producing a masking tape according to 2 .