JPH0734051A - Acrylic adhesive composition and double-sided adhesive tape - Google Patents

Abstract

(57) [Summary] [Purpose] Double-sided adhesive that allows the material of the adherend to be easily separated and recovered because the adhesiveness of the adhesive layer after setting and fixing the adherend material has completely disappeared over time. Provided are an acrylic pressure-sensitive adhesive composition for tape, and a double-sided pressure-sensitive adhesive tape using the same. [Structure] 1 part by weight of process oil to which 1 part by weight of barium stearate was added in terms of solid content was used as a core agent, which was dispersed in a THF solution of polyethylene, and this aqueous solution was introduced into water and heated. Diffuse and have a particle size of 0.5
A microcapsule (solution B) having a size of ˜5 μm is produced. Using 50 parts by weight of butyl acrylate, 50 parts by weight of 2-ethylhexyl acrylate, and 2 parts by weight of acrylic acid, an acrylic pressure-sensitive adhesive solution (liquid A) having an average molecular weight of 500,000 is obtained by a solution polymerization method. Acrylic adhesive solution (solution A) 10
2 parts by weight of microcapsules (Liquid B) was blended with 0 parts by weight, and the mixture was stirred and mixed with a dissolver for 30 minutes to obtain an acrylic pressure-sensitive adhesive composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic pressure-sensitive adhesive composition suitable for use as a pressure-sensitive adhesive for a double-sided pressure-sensitive adhesive tape used in a field in which a material for an adherend is recovered and reused, that is, a field requiring so-called recycling. And a double-sided pressure-sensitive adhesive tape using the acrylic pressure-sensitive adhesive composition.

[0002]

2. Description of the Related Art Generally, when an acrylic pressure-sensitive adhesive that causes a cross-linking reaction with a cross-linking agent, a so-called cross-linking type acrylic pressure-sensitive adhesive is cross-linked with a cross-linking agent, a three-dimensional polymer substance having both viscoelasticity in addition to adhesiveness is obtained. Since it has excellent adhesiveness to various materials such as metal and plastic, for example,
As an interior material in the field of automobile industry, it can be used as a pressure-sensitive adhesive of a double-sided pressure-sensitive adhesive tape for fixing a foam material such as urethane foam or polyethylene foam as a cushion material to a base material made of metal or plastic.

[0003]

Recently, in the automobile industry and the like, the promotion of recycling of materials has been called for. However, the double-sided adhesive tape using the cross-linking acrylic adhesive as described above is applied to When the interior materials are fixed by fixing the materials of the body, it is difficult to separate the materials easily because the adhesiveness of the adhesive remains even at the time when it needs to be recycled, and the recovery rate is poor and the recycling is difficult. There is a problem that it cannot be performed sufficiently and smoothly.

The present invention solves the above-mentioned problems of the prior art, and the adhesiveness of the adhesive layer after fixing and setting the material of the adherend is completely lost over time, and the material of the adherend is easily separated. The present invention has been made for the purpose of providing an acrylic pressure-sensitive adhesive composition for a double-sided pressure-sensitive adhesive tape that can be collected and recovered, and a double-sided pressure-sensitive adhesive tape using the acrylic pressure-sensitive adhesive composition.

[0005]

MEANS FOR SOLVING THE PROBLEMS The present invention 1 is an acrylic pressure-sensitive adhesive composition in which microcapsules are dispersed in an acrylic pressure-sensitive adhesive, wherein the microcapsules are formed by crosslinking the acrylic pressure-sensitive adhesive in the coating film. An acrylic pressure-sensitive adhesive composition comprising an agent and a softening agent, the coating of which is destroyed by a predetermined pressure.

In the present invention 1, as the acrylic pressure-sensitive adhesive, for example, a polymer composed of an acrylic monomer containing (meth or) acrylic acid alkyl ester as a main component is typical. As a specific example of the body,
Preferred is a (meth or) acrylic acid alkyl ester (usually having an alkyl group having 10 or less carbon atoms) or a copolymer thereof with a vinyl monomer having a polar group such as a carboxyl group in a side chain. Used for. As the ester, isooctyl ester, 2-ethylhexyl ester, n-propyl ester, isopropyl ester, ethyl ester and the like are preferable.

In the present invention 1, as the crosslinking agent for the acrylic pressure-sensitive adhesive, for example, an organic metal salt such as zinc stearate or barium stearate, an isocyanate crosslinking agent,
Epoxy cross-linking agent is used.

The amount of the crosslinking agent added is 10
1 to 10 parts by weight is preferable with respect to 0 parts by weight. If the addition amount is less than 1 part by weight, the crosslinking reaction is difficult to proceed,
On the other hand, when it exceeds 10 parts by weight, the crosslinking reaction proceeds at the initial stage, and the initial adhesive strength becomes low.

In the present invention 1, examples of the softening agent for the acrylic pressure-sensitive adhesive include petroleum-based softening agents such as process oil and extender oil, liquid rubbers such as polyisobutylene, polybutene and liquid polyisoprene, and dibasic acid esters. A synthetic plasticizer such as a system plasticizer is used.

The amount of the softening agent added is 10
1 to 10 parts by weight is preferable with respect to 0 parts by weight. If the addition amount is less than 1 part by weight, the initial tack is low, and conversely,
If it exceeds 10 parts by weight, the cohesive force will decrease.

In the present invention 1, a crosslinking agent for an acrylic pressure-sensitive adhesive and a softening agent are microencapsulated, dispersed in an acrylic pressure-sensitive adhesive solution, and the microcapsules are destroyed at the time when the crosslinking reaction is required. Therefore, the pot life is increased, the viscosity does not increase even after coating and drying, and the impregnation property and transfer property to the substrate are not hindered. After the adhesive has hardened to exhibit the desired cohesiveness and the material of the adherend has been fixed and set, over time, the cross-linking agent in the state of being dissolved in the softening agent has not spread evenly throughout the adhesive layer. The cross-linking reaction with the functional group of the reaction completely progresses, the tackiness of the pressure-sensitive adhesive layer disappears, and the material of the adherend can be easily recovered.

By the way, the technique of microencapsulation has been known for a long time, and it is a technique of encapsulating a finely divided liquid or solid substance with thin plastic or wax to make it into small particles. A solid substance is called a core or core, and a substance containing this is called a film or a wall film. In the technical field of adhesive tape, it may be used for the purpose of retaining the delayed action of a drug like a drug tape or a sheet, but the present invention uses this technique to control the reaction of a crosslinking agent and This is applied to the disappearance of the adhesiveness of the adhesive layer over time.

At the time of encapsulation, in the present invention, a crosslinking agent for an acrylic pressure-sensitive adhesive and a softening agent are dispersed as fine particles in an encapsulating medium such as a solvent as a core, and a coating substance is introduced into the dispersion to form a core. A method of encapsulating by encapsulating or depositing this around the agent is adopted.

The pressure required for breaking the obtained capsule is
There is no particular limitation, but usually, 5 Kg / cm ² is preferable.

The present invention 2 is a double-sided pressure-sensitive adhesive tape using the acrylic pressure-sensitive adhesive composition of the invention 1.

As shown in FIG. 1, the double-sided pressure-sensitive adhesive tape of the present invention 2 comprises a base material 111 and pressure-sensitive adhesive layers 112 and 112 made of the acrylic pressure-sensitive adhesive composition of the present invention 1 provided on both surfaces thereof. . As the base material 111, non-woven fabric, paper, cellophane, synthetic resin film or the like is preferably used.

The double-sided pressure-sensitive adhesive tape 11 is provided with pressure-sensitive adhesive layers 112, 112 by applying an acrylic pressure-sensitive adhesive composition to a substrate 111 by a transfer method. At this time, in the pre-transfer stage, the cross-linking reaction does not occur, the original viscosity is maintained, and thus good transfer performance is exhibited, and at the same time, the pressing force during transfer is used to form the microcapsules. By destroying, the initial cohesive force of the obtained pressure-sensitive adhesive layer is increased to stabilize the initial various physical properties required for the double-sided pressure-sensitive adhesive tape.

Next, an example of usage of the double-sided adhesive tape of the present invention 2 will be described with reference to FIGS. 2 and 3. As shown in FIG. 2, reference numeral 1 denotes an automobile interior material, and a cross-section as a cushioning material on the front surface of the back surface of a synthetic resin molded product 12 having a substantially L-shaped cross section, with a double-sided adhesive tape 11 of the present invention 2 interposed therebetween. It is composed of a substantially L-shaped urethane foam 13 fixed thereto.

As shown in FIG. 3, the interior material 1 for an automobile covers the floor and walls of the trunk of the automobile,
It is set so that its side edge is locked by the locking portion 2. Then, the adhesive layer 112 of the double-sided adhesive tape 11
Has gradually decreased in adhesiveness over time, and finally,
The tackiness is completely lost. If the adhesiveness of the pressure-sensitive adhesive layer 112 is adjusted to be completely lost when the automobile interior material 1 needs to be recycled, when the automobile interior material 1 is opened and taken out, it is possible to remove the adhesive. It is possible to easily separate and collect the synthetic resin molded product 12 and the urethane foam 13 that are the materials of the adhered body.

The interior material 1 for an automobile must be fixed by the double-sided adhesive tape 11 between the synthetic resin molded product 12 and the urethane foam 13 until it is set in the luggage compartment. After that, since the urethane foam 13 is sandwiched between the floor and the wall of the trunk of the automobile and the synthetic resin molded product 12, the synthetic resin molded product 12 and the urethane foam 13 are sandwiched.
Even if the space is not fixed by the double-sided adhesive tape 11,
There is no adverse effect such as the urethane foam 13 moving in position.

[0021]

The acrylic pressure-sensitive adhesive composition of the present invention 1 is an acrylic pressure-sensitive adhesive composition in which microcapsules are dispersed in the acrylic pressure-sensitive adhesive. A cross-linking agent and a softening agent are enclosed,
When the acrylic pressure-sensitive adhesive composition is applied to the base material by the transfer method, the coating does not cause a cross-linking reaction in the pre-transfer step, because the coating is made of a material that is destroyed by a predetermined pressure. While maintaining the viscosity to exhibit good transfer performance, the pressing force at the time of transfer is used to destroy the microcapsules, and the initial cohesive force of the obtained adhesive layer is increased, resulting in double-sided adhesion. It is possible to provide a double-sided pressure-sensitive adhesive tape having stable initial physical properties required for the tape.
Further, when a large amount of the pressure-sensitive adhesive composition is produced and temporarily stored, the pressure-sensitive adhesive composition can be stored for an arbitrary period without being bothered by the progress of the crosslinking reaction.

Moreover, since the softening agent is present together with the cross-linking agent in the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive tape after the material for the adherend is fixed and set, the cross-linking agent adheres in the state of being dissolved in the softening agent. It spreads evenly over the entire agent layer, and over time, the crosslinking reaction with the unreacted functional group proceeds completely, the gel fraction rises, and finally its tackiness disappears. If this time is adjusted so that it is a time to recycle the material of the adherend, it can be used as a pressure-sensitive adhesive for double-sided pressure-sensitive adhesive tape that can open the setting and easily separate and collect the material of the adherend. It can be used preferably.

The double-sided pressure-sensitive adhesive tape of the present invention 2 is excellent in initial physical properties required for the double-sided pressure-sensitive adhesive tape by using the acrylic pressure-sensitive adhesive composition of the present invention 1. It can be firmly fixed and set, and the adhesive property of the adhesive layer disappears over time, so the material of the adherend can be easily separated and collected at the time when the material of the adherend needs to be recycled. It can be recycled.

[0024]

EXAMPLES Examples 1-3 . Micro-encapsulated process oil of cross-linking agent and softening agent (Kyodo Oil Co., Ltd., trade name "R-20
0 ") 1 part by weight of the cross-linking agent shown in Table 1 in terms of solid content was added as a core agent, which was dispersed in a tetrahydrofuran (THF) solution of polyethylene to prepare an aqueous solution. Was introduced into water and diffused by heating to produce microcapsules (solution B) having a particle size of 0.5 to 5 μm. As the barium stearate, a product manufactured by Sakai Chemical Industry Co., Ltd. was used, as the isocyanate compound, product name “Coronate L55E” manufactured by Nippon Polyurethane Industry Co., Ltd. was used, and as an epoxy compound, product name “Eken Chemical Co., Ltd.” was used. -AX "was used.

[0025]. Manufacture of acrylic adhesive solution Using 50 parts by weight of butyl acrylate, 50 parts by weight of 2-ethylhexyl acrylate, and 2 parts by weight of acrylic acid,
By the solution polymerization method, an acrylic pressure-sensitive adhesive solution (liquid A) having an average molecular weight of 500,000 was obtained. ． Preparation of acrylic pressure-sensitive adhesive composition With respect to 100 parts by weight of the acrylic pressure-sensitive adhesive solution (liquid A),
2 parts by weight of microcapsules (Liquid B) were mixed and stirred and mixed with a dissolver for 30 minutes to prepare an acrylic pressure-sensitive adhesive composition of the present invention.

.. The acrylic pressure-sensitive adhesive composition was applied to a release sheet obtained by subjecting the surface of woodfree paper to a release treatment to a thickness of 50 μm using a 2-roll coater, and introduced into a drying oven at 110 ° C. to volatilize the solvent. Then, two pressure-sensitive adhesive sheets to which the pressure-sensitive adhesive layer was temporarily attached were manufactured. Next, it is fed to a transfer roll together with a base material made of a cellulose-based non-woven fabric (basis weight = 14 g / m ² , thickness = 40 μm) so that the base material is sandwiched and the pressure-sensitive adhesive layer overlaps the base material. 1
A double-sided pressure-sensitive adhesive tape was obtained by applying a pressing force of 0 g / cm to transfer the pressure-sensitive adhesive layer to both sides of the substrate.

Comparative Example 1 Examples 1 to 1 except that microcapsules were not used
A double-sided adhesive tape was obtained in the same manner as in 3. Comparative Examples 2 to 4 Double-sided pressure-sensitive adhesive tapes were obtained in the same manner as in Examples 1 to 3 except that the softening agent was not included in the microcapsules.

The following evaluation tests were carried out on the double-sided pressure-sensitive adhesive tapes obtained in Examples 1 to 3 and Comparative Examples 1 to 4 above.
The results are shown in Table 1.

The evaluation test methods and evaluation criteria are as follows. ． SP adhesive strength: Adhesive double-sided tape having a width of 15 mm was adhered to a stainless steel plate, and a 2 Kg rubber roll was pressed back and forth once to measure initial adhesive properties and adhesive properties after 60 days under a temperature condition of 80 ° C. did. Incidentally, S
With respect to the P adhesive strength (initial), those having 500 g / 25 mm or more were evaluated as ◯, and those having less than 500 g / 25 mm were evaluated as x. Also, SP adhesive strength (80 ° C x 60 days later) is 50g
/ Less than 25 mm is ○ (removable with time), 50
Those having g / 25 mm or more were evaluated as x (no removability with time).

.. Ball tack: J. According to the ball tack test method of Dow method, the initial ball tack and the ball tack after 60 days under the temperature condition of 80 ° C. were measured. In addition, in the ball tack (initial),
A rating of 7 or more was evaluated as ◯, and a rating of less than 7 was evaluated as x.
In the ball tack (after 80 ° C. × 60 days), those having a rating of 3 or less were evaluated as ◯ (removable with time) and those having a rating of 3 or more were rated as × (not removable).

[0031]

[Table 1]

As is clear from Table 1, the acrylic pressure-sensitive adhesive compositions containing a crosslinking agent and a softening agent as in Examples 1 to 3 of the present invention are excellent in initial tackiness, and Excellent removability over time.

[0033]

EFFECT OF THE INVENTION Since the acrylic pressure-sensitive adhesive composition of the present invention 1 has the above-mentioned constitution, it has excellent initial physical properties required for a double-sided pressure-sensitive adhesive tape and produces a large amount of pressure-sensitive adhesive composition. However, in the case of temporary storage, it is possible to store for any period without being bothered by the progress of the crosslinking reaction, and after fixing the material of the adherend, the material of the adherend over time. Can be suitably used as a pressure-sensitive adhesive for a double-sided pressure-sensitive adhesive tape that can be easily peeled off and collected.

Since the double-sided pressure-sensitive adhesive tape of the second aspect of the present invention is constructed as described above, it is possible to firmly and fixedly set the material of the adherend, and it is necessary to recycle the material of the adherend over time. At any time, the setting can be opened and the material of the adherend can be easily peeled off and collected for recycling.

[0035]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a double-sided adhesive tape of the present invention 2.

FIG. 2 is a cross-sectional view showing an example of usage of the double-sided pressure-sensitive adhesive tape of the second invention.

FIG. 3 is a cross-sectional view showing an example of usage of the double-sided pressure-sensitive adhesive tape of the invention 2.

[Explanation of symbols]

 1 Automotive Interior Material 2 Locking Part 11 Double-sided Adhesive Tape 12 Synthetic Resin Molded Product 13 Urethane Foam 111 Base Material 112 Adhesive Layer

Claims (2)

[Claims] 1. An acrylic pressure-sensitive adhesive composition in which microcapsules are dispersed in an acrylic pressure-sensitive adhesive, wherein the microcapsules have a cross-linking agent and a softening agent of the acrylic pressure-sensitive adhesive enclosed in a coating film. An acrylic pressure-sensitive adhesive composition, characterized in that the coating film is one that is destroyed by a predetermined pressure. 2. A double-sided pressure-sensitive adhesive tape using the acrylic pressure-sensitive adhesive composition according to claim 1.