JPH10147760A - Adhesive tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive tape which does not undergo lifting or release during the period of curing therewith and can be easily released without being torn after the curing by forming an adhesive layer on the entire of either surface of a support so that the adhesiveness of the layer may vary in the direction of width of the tape. SOLUTION: This tape consists of a support and an adhesive layer formed on the entire of either surface of the support and having adhesiveness differing at the both ends in the direction of width and at the center. It is desirable that in the adhesive layer, the adhesiveness in the part confined by each end of the tape and the line distant therefrom by 3-15% of the entire width of the tape is 5-70% of that at the other part. The thickness of the adhesive layer is suitably determined according to a object of use, and is usually about 5-50μm, desirably 10-40μm. Although not particularly limited, the adhesive is exemplified by a rubbery, acrylic or silicone based one. The support is exemplified by kraft paper, Japanese paper, crape paper or a perforated plastic film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an adhesive tape. More specifically, the present invention relates to an adhesive tape which does not float or peel off during a tape curing period and can be peeled off without tearing after fulfilling a curing purpose.

[0002]

2. Description of the Related Art An adhesive tape used as a masking tape does not float or peel off during a tape curing period, and after the curing purpose is fulfilled, the tape does not tear without tearing. Is required to be peelable. As such an adhesive tape, a tape in which the same pressure-sensitive adhesive is uniformly applied to one surface of a substrate,
Alternatively, there is a tape in which an adhesive is partially applied to one surface of a substrate.

However, when the above-mentioned pressure-sensitive adhesive tape is used as a masking tape, the tape may be torn when the tape is peeled off after being adhered to an adherend and fulfilling the curing purpose. When the base material is a plastic such as polyester or polypropylene, this phenomenon is not so remarkable, but the base material is a paper material such as kraft paper, Japanese paper and crepe paper, that is, the strength of the base material is relatively small compared to the plastic. When small, this phenomenon occurred frequently.

[0004] It is said that the above phenomenon occurs because the balance between the adhesive strength of the adhesive and the strength of the substrate is lost. Therefore, in order to make the adhesive tape adhere well to the adherend, if the adhesive force of the adhesive is increased, when the tape is peeled, the adhesive force is too large, so the strength of the base material cannot withstand it, and the tape There was a problem of tearing. Conversely, if the adhesive strength of the adhesive is reduced so that the tape does not tear when peeling the adhesive tape, the tape does not stick to the adherend or the tape floats or peels off during the curing period There was a problem.

[0005] It is an object of the present invention to solve the above problems and to provide an adhesive tape which does not float or peel off during the tape curing period and which can be easily peeled without tearing after fulfilling the curing purpose.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, the phenomenon that the tape is torn when the tape is peeled off mainly occurs from the end in the tape width direction. From this, it was found that the influence of the adhesive force at the end in the tape width direction was very large, and the present invention was completed.

That is, the present invention provides (1) a pressure-sensitive adhesive tape having a base material and a pressure-sensitive adhesive layer provided on the entire surface of one side of the base material and having different adhesive strengths at an end and a center in a width direction.
(2) In the pressure-sensitive adhesive layer, a portion (hereinafter, referred to as “weakly-adhesive portion”) of 3 to 15% of the entire tape width in the width direction from both ends of the tape is a remaining portion (hereinafter, “strongly-adhesive portion”).
The adhesive tape according to the above (1), which has an adhesive force of 5 to 70% of the adhesive force of (1), (3) the adhesive is selected from the group consisting of a rubber adhesive, an acrylic adhesive, and a silicone adhesive. (1) The pressure-sensitive adhesive tape according to (1) or (2), wherein the pressure-sensitive adhesive layer has a thickness of 5 to 50 μm. The tape, (5) the adhesive tape according to (1) or (2), wherein the substrate is a porous substrate, and (6) the porous substrate has kraft paper, Japanese paper, crepe paper, and through holes. The present invention relates to the pressure-sensitive adhesive tape according to the above (5), which is a substrate selected from the group consisting of a plastic film.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The pressure-sensitive adhesive used in the present invention is applied on one entire surface of a substrate and has a different adhesive strength in the width direction. In order to make the adhesive strength different in the width direction, two kinds of adhesives having different adhesive strengths are applied.

The pressure-sensitive adhesive used in the present invention is not particularly limited, and a known pressure-sensitive adhesive can be appropriately selected and used. For example, a rubber-based adhesive, an acrylic-based adhesive, and a silicone-based adhesive can be used.

As the rubber-based pressure-sensitive adhesive, any of a natural rubber-based pressure-sensitive adhesive and a synthetic rubber-based pressure-sensitive adhesive may be used. Examples of the synthetic rubber-based adhesive include styrene-isoprene block copolymer (SIS), styrene-butadiene rubber (SBR),
Isoprene rubber (IR), polyisobutylene (PI
B) and butyl rubber (IIR).

Examples of the acrylic pressure-sensitive adhesive include alkyl (meth) acrylate monomers such as ethyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, acrylic acid, methacrylic acid, and itacone. A homopolymer or a copolymer of an acrylic monomer such as a carboxyl group-containing monomer such as an acid, maleic acid, and crotonic acid may be used. Further, copolymers of these monomers and monomers copolymerizable with the monomers are also included. The polymerization is not particularly limited, and examples thereof include solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization.

Examples of the silicone-based pressure-sensitive adhesive include known silicone-based pressure-sensitive adhesives such as a peroxide-crosslinkable silicone-based pressure-sensitive adhesive and a hydrosilyl-type (addition-reaction-type) silicone-based pressure-sensitive adhesive.

Examples of the adhesive applied to the weak adhesive portion include 2-ethylhexyl acrylate, SBR, PI
B and the like. The adhesive strength is preferably 5 to 400 g / 20 mm, more preferably 20 to 200 g / 20 mm, although it depends on the type of the adherend. Examples of the adhesive applied to the strongly adhesive portion include 2-ethylhexyl acrylate, SIS, and IR. The adhesive strength depends on the type of the adherend, but 100-600 g
/ 20 mm is preferable, and 200 to 40 is more preferable.
0 g / 20 mm.

The magnitude of the adhesive strength of the weakly adhesive part and the strongly adhesive part was measured according to JIS Z-0237 (180 ° peeling).

The combination of the adhesive applied to the weakly adhesive part and the strongly adhesive part is not particularly limited as long as the adhesive strength of the weakly adhesive part is 5 to 70% of the adhesive strength of the strongly adhesive part. For example, the type of the base polymer constituting the pressure-sensitive adhesive is the same, and a combination of a pressure-sensitive adhesive whose adhesive force is changed by changing an additive component such as a cross-linking agent or a tackifier added to the base polymer; Combinations of different types of base polymers, such as adhesives and acrylic adhesives,
And even in the case of a combination of rubber-based pressure-sensitive adhesives or acrylic pressure-sensitive adhesives, a combination of pressure-sensitive adhesives of different types of base polymer (specifically, an acrylic polymer and a base polymer in both the weakly adhesive portion and the strongly adhesive portion) Combinations in which the type (copolymer composition, etc.) of each acrylic polymer is different). Above all, in order to satisfy various characteristics required for the adhesive tape other than the adhesive strength (for example, contamination to the adherend surface, etc.), an adhesive using the same base polymer composed of the combination shown above. Is excellent in that only the adhesive strength is changed and there is no great difference in other properties.

The range of the weak adhesive portion is preferably 3 to 15%, more preferably 5 to 12% of the total tape width in the width direction from both ends of the adhesive tape. If the range of the weakly adhesive portion is less than 3%, stress concentrates on the end in the tape width direction at the time of tape peeling, and there is a tendency that tape breakage at the time of tape peeling cannot be prevented. Further, if the range of the weakly adhesive portion exceeds 15%, the weakly adhesive portion of the adhesive tape becomes large, and as a result, does not adhere to the adherend,
Alternatively, the tape tends to peel off when the tape is attached.

The magnitude of the adhesive force of the weakly adhesive portion is preferably 5 to 70%, more preferably 10 to 50% of the adhesive force of the strongly adhesive portion. Adhesive strength of weak adhesive part is 5
%, The difference in the adhesive strength in the width direction of the adhesive tape is too large, so that the adhesive tape does not adhere to the adherend or the tape tends to peel off when the tape is attached. Also, if the magnitude of the adhesive force of the weak adhesive portion exceeds 70%, the difference in the adhesive force in the width direction of the adhesive tape is too small, and stress concentrates on the end portion in the tape width direction when the adhesive tape is peeled off. As a result, there is a tendency that tape breakage during tape peeling cannot be prevented.

[0018] If necessary, a crosslinking agent may be added to the pressure-sensitive adhesive.
Known additives such as tackifiers, softeners, antioxidants, fillers, release agents, tackifiers, plasticizers, stabilizers, pigments, and antioxidants may be blended.

The thickness (after drying) of the pressure-sensitive adhesive layer is appropriately determined depending on the purpose and is about 5 to 50 μm, preferably 1 to 50 μm.
0 to 40 μm.

The substrate used in the present invention is not particularly limited. For example, polypropylene, polyester,
Hot-melt perforation on plastic substrates such as polyethylene, polyvinyl chloride, etc. and kraft paper, Japanese paper (for example, Japanese paper mixed with beaten wood pulp and hemp or synthetic staple fiber), crepe paper, or plastic film such as polypropylene For example, a porous substrate such as a plastic film in which a large number of fine through holes are formed by a method or the like.

The average opening diameter of the through holes is 0.1 to 100 μm.
m, preferably 0.5 to 70 μm.

The density of the through holes is 500 /
cm ² or more, more preferably 500 to 5,0
00 pieces / cm ² , more preferably 1,000 to 5,0
00 / cm ² .

The method of perforating the through-hole includes a method known per se, for example, a method of perforating by passing a base material between a roll having fine projections on the surface and a roll having a smooth surface. .

The substrate of the present invention is preferably a porous substrate from the viewpoint of good hand-cutting properties.

The substrate used in the present invention may be subjected to a back surface treatment or an undercoat, if necessary.
For the back surface treatment, a long-chain alkyl-based release agent or a silicone-based release agent is used.

The thickness of the substrate used in the present invention is usually 3
It is about 0 to 150 μm, preferably 50 to 100 μm.

The production of the pressure-sensitive adhesive tape includes, for example, two-time coating in which a pressure-sensitive adhesive for a weakly adhesive portion is applied, and then a pressure-sensitive adhesive for a strongly adhesive portion is applied.

[0028]

EXAMPLES Examples and comparative examples are shown below, but the present invention is not limited by these examples. Table 1 shows the compositions of the pressure-sensitive adhesives used in Examples and Comparative Examples.

[0029]

[Table 1]

Example 1 A porous base material (20 mm width) obtained by impregnating a paper material having a basis weight of 30 g / m ² (wood pulp: polyester (PET) = 80: 20 mixed paper) with butyl rubber was used. The emulsion-based pressure-sensitive adhesive A has a width of 16 mm, and the acrylic-based emulsion pressure-sensitive adhesive B has a width of 2 mm at both ends.
It was applied so as to have a thickness of 0 μm (dry film thickness) to prepare an adhesive tape.

Example 2 Rubber-based adhesive C was applied to a crepe paper (40 mm width) having a basis weight of 70 g / m ^{2 in} a width of 36 mm, and rubber-based adhesive D was applied to both ends of 2 m.
The adhesive tape was applied to each of the m widths so as to have a thickness of 30 μm (dry film thickness).

Example 3 Rubber-based pressure-sensitive adhesive C was 35 mm in width, acrylic emulsion-type pressure-sensitive adhesive B was 7.5 mm in width on both ends, and was 25 μm (dry) on kraft paper (50 mm width) having a basis weight of 73 g / m ^2. To form a pressure-sensitive adhesive tape.

Comparative Example 1 A pressure-sensitive adhesive tape was prepared in the same manner as in Example 1 except that the acrylic emulsion-type pressure-sensitive adhesive A was applied to the entire surface of the pressure-sensitive adhesive tape in a width direction of 20 mm.

Comparative Example 2 An adhesive tape was prepared in the same manner as in Example 1 except that the acrylic emulsion-type adhesive B was applied to the entire surface of the adhesive tape in a width direction of 20 mm.

Using the adhesive tapes obtained in Examples 1 to 3 and Comparative Examples 1 and 2 as samples, the adhesive strength of the weakly and strongly adhesive portions of the adhesive tape, the presence or absence of floating or peeling after tape application, The tearability at the time of tape peeling and the tensile strength of the pressure-sensitive adhesive tape were measured and evaluated. The respective measuring methods and evaluation methods are as follows.

[Adhesive Strength of Weakly Adhered Area and Strongly Adhered Area]
The adhesive strength was measured at 180 ° peeling according to JIS Z-0237.

[Presence of Floating or Peeling After Tape Adhesion] The adhesive tape was left on a stainless steel plate (SUS304BA) which had been washed with toluene in advance at 23 ° C. × 65% RH for 2 days, and then visually observed. Floating or peeling was confirmed. ：: No lifting or peeling occurred. ×: Floating or peeling occurred.

[Tearability at Peeling of Tape] An adhesive tape (30 cm in length) was attached to a stainless steel plate (SUS304BA), and after leaving for one week, the adhesive tape was moved in the direction of 180 °.
The tearability of the tape when peeled at a speed of m / min was confirmed. ：: The tape substrate was not broken at the time of peeling, and could be easily peeled. X: The tape substrate was torn at the time of peeling, and peeling was difficult.

Table 2 shows the measurement results.

[0040]

[Table 2]

[0041]

According to the pressure-sensitive adhesive tape of the present invention, the adhesive strength of the pressure-sensitive adhesive and the strength of the substrate can be easily balanced, so that the tape can be designed with a wide range. In addition, the tape can be prevented from floating or peeling during the tape curing period, and the tape can be prevented from breaking when the tape is peeled off, so that it can be suitably used particularly as a masking tape.

Claims (6)

[Claims] 1. A pressure-sensitive adhesive tape having a base material and a pressure-sensitive adhesive layer provided on the entire surface of one side of the base material and having different adhesive strengths at an end and a center in a width direction. 2. The pressure-sensitive adhesive layer, wherein a portion of 3 to 15% of the entire tape width in the width direction from both ends of the tape has an adhesive force of 5 to 70% of an adhesive force of the remaining portion.
The adhesive tape as described. 3. The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive is at least one type of pressure-sensitive adhesive selected from the group consisting of a rubber pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, and a silicone pressure-sensitive adhesive. 4. The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 5 to 50 μm. 5. The pressure-sensitive adhesive tape according to claim 1, wherein the substrate is a porous substrate. 6. The adhesive tape according to claim 5, wherein the porous substrate is a substrate selected from the group consisting of kraft paper, Japanese paper, crepe paper, and a plastic film having through holes.