JP3284205B2 - Reinforced adhesive 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 reinforced double-sided pressure-sensitive adhesive tape having a strong adhesive force, a strong adhesive force and a high holding force, reinforced by fibers. More specifically, the present invention relates to a double-sided adhesive tape used for fixing an automobile side molding, various ribs, various panels, and the like for substructure bonding.

[0002]

2. Description of the Related Art Conventionally, double-sided pressure-sensitive adhesive tapes are generally made of a low-stretch base material such as rayon wet nonwoven fabric or polyester film, and are adhered to a name plate, urethane foam, etc. It is used in a wide range of applications such as cushioning materials, automobile interiors, building interiors, and envelopes. On the other hand, double-sided tapes using foam base materials such as polyethylene foams and rubber foams are also subject to high loads such as fixing of side moldings of automobiles and emblem electric wiring devices, fixing of household hook hangers, and fixing of towel racks. Used for applications. In particular, those using a foam as a base material have been widely used in place of a liquid adhesive such as a solvent type or an emulsion type in place of a liquid adhesive, and have been widely used in building materials in recent years.

[0003]

The rayon wet nonwoven fabric and polyester film are thin and hardly stretched, so that a tape using the same as a base material is difficult to obtain a high thickness. It is also difficult to bond the material to the original curved surface. With such a tape, there is a limit in its adhesive strength and it is difficult to substitute the adhesive. In addition, although a foam using a foam such as polyethylene, chloroprene rubber, or butyl rubber as a base material has a foamed layer and thus has a slight followability to curved surface application, the interlayer strength of the base material is weak, and a high adhesive strength is obtained. Even if an adhesive that can be used is used, the adhesive strength is limited by the breaking strength of the base material, or there is a problem in that there is a problem in the interfacial adhesive strength between the base material and the adhesive and the limit of the adhesive strength is determined. there were. In addition, it is difficult to manufacture a thin material because it is a foam. Generally, the thickness is limited to about 0.8 mm to 2 mm, so that there is no problem even if the adhesive layer is thick. It also has the disadvantage of being limited to

In recent years, pressure-sensitive adhesive tapes using acrylic foam have become widespread, and acrylic foams are manufactured by a polymerization method using ultraviolet light or electron beam irradiation, and those manufactured by casting and drying an emulsion acrylic resin. However, the former is very costly, and also has the surface that the whole adhesive becomes harder because the adhesive force with the adhesive provided on the surface is controlled by polarity, and the adhesive force to the rough surface is reduced. I have. Therefore, when such a tape is used, the application of a primer to an adherend is a standard operation. Further, the latter has a drawback that the adhesive force on the foam surface is reduced due to the use of a surfactant or the like, and the breakage between the base material and the adhesive is likely to occur after the adhesive layer is provided on the foam. I was An object of the present invention is to provide a double-sided pressure-sensitive adhesive tape which solves these defects at once, is low-cost, adheres widely to various adherends, and exhibits high final adhesive strength.

[0005]

The inventor of the present invention has made intensive studies to overcome the problems of the prior art,
As a base material, a nonwoven fabric having a certain fiber length or more and an apparent density not more than a certain value is used, and it is found that the above object can be achieved by giving the degree of impregnation of the adhesive, and the present invention is completed based on the knowledge. Reached. That is, the present invention uses a fiber having an average filament length of 20 mm or more, impregnating a nonwoven fabric with an apparent density of 0.15 g / cm ³ or less and a basis weight of 20 to 100 g / m ² with an adhesive. The present invention relates to a reinforced double-sided pressure-sensitive adhesive tape, wherein an apparent density (d) of the pressure-sensitive adhesive tape represented by Formula 1 is 0.9 g / cm ³ or more.

## EQU00001 ## This object is achieved by an adhesive tape characterized by d = (w1 + w2) / t2 (where w1 is the basis weight of the nonwoven fabric, w2 is the amount of the adhesive applied, and t2 is the thickness of the adhesive tape). .

Hereinafter, the present invention will be described in detail. The reinforced double-sided pressure-sensitive adhesive tape of the present invention has an apparent density of 0.15 g /
A tape using a non-woven fabric having a size of ³ cm or less. The pressure-sensitive adhesive and the non-woven fabric mutually reinforce each other by impregnating the non-woven fabric with the pressure-sensitive adhesive. This is to constitute an adhesive tape having strong peeling resistance.

Although it is not necessary to specify the production method of the nonwoven fabric as the base material, it is preferable that the binder is not used or the content is 20% by weight or less even if the binder is used. Therefore, a nonwoven fabric by a dry method, a spunlace method, a needle punch bonding, a spray fiber method, or the like is suitable. As long as the average length of the fiber filaments of the nonwoven fabric is 20 mm or more, there is no problem even if the length is long. When the length is shorter than 20 mm, since the entanglement of the fibers is small, it is necessary to rely on binder or heat fusion for joining, and it is difficult to obtain a material having a low apparent density, and a strong peeling stress is given as a tape base material. At this time, the strength of the entanglement is so low that a sufficient peel strength cannot be obtained. When a long fiber of 20 mm or more is used, the purpose can be achieved by mechanical entanglement or partial bonding with a binder. Also, the preferred diameter of such fibers is
It is from 0.1 denier to 50 denier, more preferably from 0.1 denier to 20 denier. It is difficult to produce a fiber having a diameter smaller than 0.1 denier, and if it exceeds 20 denier, it becomes difficult to obtain entanglement of the fiber and it becomes difficult to uniformly strengthen the fiber.

It is extremely important that the apparent density of the nonwoven fabric is 0.15 g / cm ³ or less from the viewpoint of the impregnation of the pressure-sensitive adhesive and the properties of the pressure-sensitive adhesive tape. The apparent density is based on the basis weight (w1:
g / m ² ) by the apparent thickness (t1: mm). In a nonwoven fabric having a density higher than 0.15 g / cm ³ ,
When the pressure-sensitive adhesive tape is bonded to the adherend and a peeling force is applied, only the pressure-sensitive adhesive layer is deformed, so that the nonwoven fabric itself cannot be largely deformed and high adhesive strength cannot be obtained. The pressure-sensitive adhesive is hardly impregnated into the interior of a high-density nonwoven fabric, and since it becomes a laminate of the pressure-sensitive adhesive and the substrate, the effect of reinforcing each other cannot be obtained.

The basis weight of the nonwoven fabric is 20 or more and 100 g / m ^2.
Must be: When the amount is less than 20 g / m ² , the pressure-sensitive adhesive layer is not three-dimensionally reinforced with the fiber, so that the stress in the shear direction depends only on the cohesive force of the pressure-sensitive adhesive, which is not preferable. On the other hand, if it exceeds 100 g / m ² , the impregnating property becomes extremely poor and the filling of the pressure-sensitive adhesive becomes insufficient, so that the performance as a pressure-sensitive adhesive tape is significantly reduced. The ratio t1 / t2 of the apparent thickness (t1: mm) of the nonwoven fabric to the tape thickness (t2: mm) after impregnation is 0.5 or more and 2
It is preferably within the following range. When this ratio is 0.5 or less, the dispersibility of the base material in the entire tape is poor, the adhesive and the base material are close to a laminated state, and the mutual reinforcing property of the present invention is easily damaged. If the ratio exceeds 2, the proportion of the nonwoven fabric in the volume of the tape becomes too large, and the pressure-sensitive adhesive cannot sufficiently reinforce and strengthen the nonwoven fabric.

It is important that the apparent density (d) of the pressure-sensitive adhesive represented by the formula 1 is 0.9 g / cm ³ or more from the viewpoint that the pressure-sensitive adhesive reinforces the nonwoven fabric. (W1 + w2), that is, the apparent density of the tape obtained by dividing the weight per unit area of the tape by the tape thickness t2 indicates that the true specific gravity of the adhesive is a polymer substance,
, Which is an index indicating the degree of impregnation of the nonwoven fabric with the adhesive. If this value is less than 0.9 g / cm ³ , the pressure-sensitive adhesive will not have the effect of sufficiently wetting and reinforcing the fibers of the nonwoven fabric, and will not have the breaking strength as a tape.

It is desirable that the basis weight of the nonwoven fabric is 20 g / m ² or more. Although the upper limit is not necessary in terms of the structure of the double-sided pressure-sensitive adhesive tape, a reinforcing effect of the pressure-sensitive adhesive tape cannot be sufficiently obtained at 20 g / m ² or less, and when the weight is extremely high, it becomes difficult to impregnate the pressure-sensitive adhesive inside. .

Synthetic rubber latex, butadiene acrylonitrile, emulsions of poly (meth) acrylate, and the like are often used as binders for nonwoven fabrics. Binders have a curing effect in addition to an adhesive effect. Therefore, if used in a large amount, the suppleness and texture of the nonwoven fabric will be impaired. In the present invention, these sensory elements are not directly related, but the fact that the binder increases the apparent density and impairs the impregnating property greatly affects the performance of the double-sided pressure-sensitive adhesive tape. In particular, when the amount of the binder is 20% by weight or more of the basis weight, such a surface becomes remarkable. Such a nonwoven fabric is manufactured by a dry method or a direct method as described above, and the bonding of the web is performed by spraying a binder, needle punching, stitching, or self-bonding. You have to stop slightly. This is because excessive heat fusion prevents impregnation of the pressure-sensitive adhesive into the fiber and significantly impairs the dispersibility of stress.

As a method for producing such a nonwoven fabric, a dry method,
Spunlace method is most suitable, but spray fiber method, spunbond method, melt blow method, etc. are performed in the direct method, and there is no problem in any method if a nonwoven fabric satisfying the above conditions is obtained. It is. As the fiber used for the nonwoven fabric, polyester, nylon, polyethylene, polypropylene, vinylon, polyurethane, acrylic, or the like is used. These synthetic fibers are easy to control the fiber length and easy to produce. Many of them are used alone and made into a nonwoven fabric, but two or more kinds can be mixed to form a nonwoven fabric. Others such as pulp, hemp,
When natural fibers such as cotton are used, the fibers are too short or the length is difficult to control, so that it is difficult to obtain the low-density nonwoven fabric according to the present invention.

The pressure-sensitive adhesive for impregnating the nonwoven fabric obtained as described above is a block copolymer represented by the general formula ABA (wherein formula A represents a styrene polymer block and B is , Represents an isoprene polymer block, a butadiene polymer block, or a hydrogenated polymer block thereof).
Natural rubber, butyl rubber, polyisobutylene, polyisoprene, acrylate polymer, polyether, silicone resin, etc. can be used, but ABA block copolymer and acrylate polymer are most suitable. These have characteristics that they can be easily impregnated into a nonwoven fabric, in addition to their performance stability and versatility. Any of these tackifier polymers may be mixed with tackifiers, stabilizers, plasticizers and other general additives for use.

The method of impregnation is a dipping method in which, when the adhesive is a solution, the nonwoven is immersed in the adhesive and dried, and a wet lamination in which the adhesive is applied, the nonwoven is laminated in an undried state, and then dried. And a transfer method in which a pressure-sensitive adhesive is made into a dry coating film and is strongly compressed and impregnated with a hot roll. When a dipping method or a wet laminating method is used, foaming is easily generated inside together with impregnation and drying of the pressure-sensitive adhesive, and the apparent density of the tape tends to hardly increase, so a slow drying step is required. Further, since the smoothness of the dried surface is impaired, it is necessary to provide the pressure-sensitive adhesive layer again by the transfer method. In this case, the pressure-sensitive adhesive previously impregnated and the pressure-sensitive adhesive layer on the surface are most preferably the same composition, but different pressure-sensitive adhesives can be used within the allowable range of the interfacial adhesive force. The thickness of the pressure-sensitive adhesive layer to be transferred later is appropriately adjusted by a standard method, and the coating film is laminated at room temperature or by heating to form a layer on a previously provided impregnated nonwoven fabric. By performing this step from both sides, a double-sided pressure-sensitive adhesive tape is obtained.

In the transfer method, the adhesive of the solution is formed into a dry coating film on release paper, or a hot melt adhesive is formed into a coating film by hot melt coating, the nonwoven fabric is laminated, and heat is applied from the release paper side and the nonwoven fabric side. Can be impregnated by applying pressure. The ABA type block copolymer pressure-sensitive adhesive is easily impregnated by applying heat of 120 ° C. or more, but very high heat is applied to an acrylic acid ester polymer having a large molecular weight or various rubber-based pressure-sensitive adhesives having a large molecular weight. And need pressure. A double-sided pressure-sensitive adhesive tape is obtained by performing the method from both sides, releasing the release paper on one side using a release paper of double-sided silicon treatment on one side, and winding the tape.

When a cross-linkable pressure-sensitive adhesive such as an acrylate polymer is used, it is preferable to slow the cross-linking reaction. The reason for this is that when the adhesive is impregnated, the heat impregnation of the transfer method is difficult to impregnate with a highly crosslinked adhesive coating film, and the adhesive does not reach the central portion of the nonwoven fabric, causing destruction between the nonwoven fabric layers. In addition, in the dipping method, since the adhesive layer is overlaid on the adhesive layer,
If crosslinking has progressed too much, even with the same type of adhesive,
This is because the adhesive is easily broken at the interface between the adhesives.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The reinforced pressure-sensitive adhesive tape thus obtained exhibits a behavior as a thick general double-sided tape when applied to an adherend, but after a lapse of time, a peeling stress is applied with an increase in interfacial adhesive force. When this occurs, the adhesive tape undergoes large deformation and exhibits extremely high adhesive strength. Hereinafter, embodiments of the present invention will be described with reference to examples and the like.

[0019]

【Example】

(Manufacture of Nonwoven Fabric 1) Using a polyester fiber having an average fiber length of 43 mm and a fiber diameter of 2 deniers, a binder-free basis weight of 20 g / m ² and an apparent thickness of 200 by a spunlace method.
A nonwoven fabric A having a thickness of μm was produced. The apparent density of the nonwoven is 0.1
g / cm ³ . The apparent thickness is 50mmφ for the terminal.
Was measured using a dial-type thickness meter (manufactured by TECLOCK). (Manufacture of nonwoven fabric 2) The average fiber length was 55 mm, the polypropylene fiber having a fiber diameter of 5 denier was 8, and the average fiber length was 38 m.
m, and a mixture of nylon fibers 2 having a fiber diameter of 10 denier at a ratio of 15% by a dry method.
Nonwoven fabric B having an m ² and an apparent thickness of 400 μm was produced. The apparent density of this nonwoven fabric was 0.09 g / cm ³ .

(Examples 1 and 2) Butyl acrylate, acrylic acid, vinyl acetate, and 2-hydroxyethyl acrylate were polymerized in ethyl acetate at a ratio of 90/3/7 / 0.06 by weight. Solid content 45%, viscosity 8000mPa · s
ec of an acrylic pressure-sensitive adhesive base polymer was obtained. The polymerized rosin pentaerythritol ester (softening point 130
° C), 10 parts by weight of an alicyclic hydrogenated petroleum resin (softening point 90
C) 10 parts by weight, 1.5 parts of trifunctional polyisocyanate (Coronate L: manufactured by Nippon Polyurethane Co.) as a crosslinking agent
Each part by weight was added and mixed well to obtain an adhesive solution. This adhesive was applied to a separator treated with a silicone release agent on one side at a wet thickness of 300 g / m ^2, and a dry film thickness of 1 g / m ^{2 was} applied.
It was 30 μm. This pressure-sensitive adhesive film was bonded to both sides of nonwoven fabrics A and B, and heat-laminated at a temperature of 120 ° C. to obtain a reinforced double-sided pressure-sensitive adhesive tape. In the nonwoven fabric A (Example 1), the tape thickness was 280 μm, the thickness ratio between the nonwoven fabric and the double-sided adhesive tape was 0.71, and the apparent density of the tape was 0.96 g /
cm ³ . In the nonwoven fabric B (Example 2), the tape thickness was 310 μm, the thickness ratio t1 / t2 was 1.3, and the apparent density of the tape was 0.92 g / cm ³ .

(Examples 3 and 4) The adhesive of Example 1 was applied 380 g / m ² on a single-sided separator in a wet state, and the nonwoven fabrics A and B were wet-laminated, dried at 80 ° C. for 20 minutes, and further dried. Example 1 on both sides of the agent-impregnated nonwoven fabric
The pressure-sensitive adhesive obtained in the above was applied as a coating film having a dry thickness of 60 μm, and was laminated at room temperature under high pressure to obtain a reinforced double-sided pressure-sensitive adhesive tape. When the nonwoven fabric A was used (Example 3), the thickness of the obtained double-sided pressure-sensitive adhesive tape was 320 μm, the thickness ratio between the nonwoven fabric and the tape was 0.63, and the apparent density of the tape was 0.96 g / cm ³ . there were. When the nonwoven fabric B was used (Example 4), the thickness of the obtained double-sided pressure-sensitive adhesive tape was 340 μm, and the thickness ratio between the nonwoven fabric and the tape was 1.1.
7. The apparent density of the tape was 0.94 g / cm ³ .

(Examples 5 and 6) A styrene block copolymer hot melt adhesive, Hibon 9771 (manufactured by Hitachi Chemical Co., Ltd.), was hot-melted, and applied at 130 ° C. by extrusion coating to 100 g / m ² on a separator. Nonwoven fabrics A and B were adhered, an adhesive layer was similarly adhered to the opposite surface of the nonwoven fabric, and the laminate was further laminated at 130 ° C. to completely impregnate the hot melt adhesive into the nonwoven fabric.
When the nonwoven fabric A was used (Example 5), the thickness of the obtained tape was 230 μm, and the apparent density of the tape was 0.96 g /
cm ³ . When non-woven fabric B was used (Example 6), the thickness of the tape was 250 μm, and the apparent density was 0.96 g.
/ Cm ³ .

(Comparative Example 1) Using the nonwoven fabric A obtained in the example, the acrylic pressure-sensitive adhesive of the example 1 was applied to a separator treated with a single-sided silicon release agent at a wet thickness of 150 g / m ^2, and the dry film thickness was 80 μm. And This pressure-sensitive adhesive film was adhered from both sides of the nonwoven fabric and laminated at room temperature to obtain a double-sided pressure-sensitive adhesive tape. The thickness of the obtained tape is 320 μm
And the apparent density was 0.63 g / cm ³ . (Comparative Example 2) Average fiber length 5 mm, apparent density 0.30 g /
A double-sided pressure-sensitive adhesive tape was prepared in the same manner as in Example 1, except that a rayon-pulp blended nonwoven fabric C having a basis weight of 17 g / m ² and a cm ³ was used as a base material. The thickness of the obtained tape was 260 μm, and the apparent density was 0.95 g / cm ³ . (Comparative Example 3) Average fiber length 23 mm, apparent density 0.25 g
A double-sided pressure-sensitive adhesive tape was prepared by forming a pressure-sensitive adhesive layer in the same manner as in Example 3 by using a polyester nonwoven fabric D having a basis weight of 32 g / m ² / cm ³ and a heat-laminating at 80 ° C. The thickness of the obtained tape is 300 μm
And the apparent density was 0.79 g / cm ³ . (Comparative Example 4) thickness 0.5 mm, apparent density 0.2 g / cm
Comparative Example 1 using the polyethylene foam sheet of No. ³ as a base material
A dry adhesive layer having a thickness of 60 μm was prepared in the same manner as in
The laminate was heat-laminated on both sides of the foam at a temperature of ° C. to form a double-sided adhesive tape on a foam substrate.

[0024] surface of the Evaluation Method peeled resulting double-sided adhesive tape, attaching the aluminum foil having a thickness of 50 [mu] m, was cut into 150 mm × 25 mm width.
The adhesive surface of this tape was adhered to a stainless steel plate SUS304 of JIS G4305 which had been polished and washed with water-resistant abrasive paper # 240, and pressed back and forth once with a 2 kg rubber roller. After leaving at 23 ° C. for 1 day, the film was peeled in the 90 ° direction and the adhesive strength was measured. Stainless steel plate of shear JIS G4305 0.5 of SUS304
Those having a thickness of mm were polished and washed with water-resistant abrasive paper # 240, and stainless steel plates were overlapped with a 25 mm × 25 mm tape and bonded together, and reciprocated by one round with a 2 kg rubber roller. After standing at 23 ° C. for 1 day, it was pulled in the 180 ° direction and the shear bond strength was measured. Peeling Creep An aluminum foil having a thickness of 50 μm was attached to one surface of the obtained double-sided pressure-sensitive adhesive tape, and cut into a width of 150 mm × 25 mm. Stainless steel plate SUS304 of JISG4305,
The adhesive surface of this tape was affixed to what was polished and washed with a water-resistant abrasive paper # 240, and pressed back and forth with a 2 kg rubber roller. After standing at 23 ° C. for 1 day, the stainless steel plate was set upside down horizontally, a weight was attached to the end of the tape, and a constant load was released in the 90 ° direction. Example 1
4. Comparative Examples 1, 2, and 4 were tested in an 80 ° C.
0 g was multiplied. Examples 5 and 6 and Comparative Example 3 were 50 ° C.
The test was performed under a load of 800 g in an atmosphere. (*) 0.5 stainless steel plate SUS304 holding force JISG4305
mm-thick one is polished and washed with water-resistant abrasive paper # 240,
The stainless steel plates were overlapped with each other with a tape of 25 mm × 25 mm and bonded together, and were pressed back and forth with a 2 kg rubber roller.
After leaving at 23 ° C. for one day, Examples 1 to 4 and Comparative Examples 1 and 2
In Examples 2 and 4, 1000 g was applied in a 70 ° C. atmosphere, and in Examples 5 and 6 and Comparative Example 3, 1000 g was applied in a shearing direction in a 50 ° C. atmosphere, and a shift after 1 hour was measured.

[0025]

The reinforced pressure-sensitive adhesive tape according to the present invention can obtain a strong adhesive performance without using various foams as a support, and can obtain excellent heat resistance and creep properties.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C09J ⁷ /00-7/04 D04H 1/00-18/00

Claims (3)

(57) [Claims] A nonwoven fabric having an average filament length of 20 mm or more, an apparent density of 0.15 g / cm ³ or less, and a basis weight of 20 to 60 g / m ² is impregnated with an adhesive. A reinforced double-sided pressure-sensitive adhesive tape, wherein the apparent density (d) of the pressure-sensitive adhesive tape represented by Formula 1 is 0.9 g / cm ³ or more. D = (w1 + w2) / t2 (where w1 is the basis weight of the nonwoven fabric (g / m ² ), w2 is the dry application amount of the adhesive, and (g / m ² ) t2 is the thickness (μm) of the adhesive tape. ) 2. The nonwoven fabric has a fiber diameter of 0.1 denier or more and 20 or more.
The reinforced double-sided pressure-sensitive adhesive tape according to claim 1, wherein the density is not more than denier. 3. The method according to claim 1, wherein the amount of the binder used in the nonwoven fabric is 2% of the basis weight.
2. The pressure-sensitive adhesive tape according to claim 1, wherein the content is 0% by weight or less.