JPS6333487A - Expansion type adhesive sheet - Google Patents

Abstract

PURPOSE:A double-sided adhesive sheet, obtained by peeling cut pieces of a molded powder article applied and fixed to a pressure-sensitive adhesive containing a foaming agent on one surface of a support sheet while subjecting the cut pieces to expansion treatment and capable of firmly and readily holding the molded powder article with a good position accuracy without giving deformation and damage. CONSTITUTION:An adhesive sheet obtained by forming a pressure-sensitive adhesive layer 3 containing a foaming agent, preferably microencapsulated agent one surface of a support sheet, e.g. PE, PP film, etc., forming a pressure- sensitive adhesive layer 3' for adhering to a support table 5 on the other surface, applying and fixing a molded powder article 1, e.g. unsintered ceramic plate, etc., on the above-mentioned adhesive layer 3, cutting the resultant material and peeling the above-mentioned cut pieces 1' while subjecting the pieces 1' to expansion treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a foam-type adhesive sheet comprising a double-sided adhesive sheet having a pressure-sensitive adhesive layer containing a foaming agent and used for producing cut pieces of powder compacts.

Conventional techniques and problems Conventionally, predetermined internal electrodes are printed on a ceramic sheet obtained by molding a mixture of ceramic powder, a binder, and a solvent, and then adhesive tape is placed on a support made of an aluminum plate or the like. A sheet method (laminating method) is known in which ceramic capacitors are stacked one on top of the other in a frame fixed through a frame and then crimped, and then the crimped body is punched out into small pieces to produce cut pieces for forming ceramic capacitor chips.

However, powder compacts like the ceramic sheets described above are easily deformed or damaged, and it is difficult to place them in a predetermined position within a frame without causing deformation or damage, which reduces manufacturing efficiency and the ability to properly cut pieces. There was a problem with poor yield. In particular, when it is necessary to obtain cut pieces with excellent dimensional accuracy, such as when obtaining cut pieces for forming ceramic capacitor chips mentioned above, it is essential to position and maintain high precision, so positioning performance is poor. In the conventional frame method, the yield was actually lower.

As a result of intensive research to solve these problems, the present inventors came up with a fixing method using an adhesive sheet instead of the frame method. According to this method of fixing a powder compact such as an unsintered ceramic plate with an adhesive sheet, the powder compact is held in a stable state and then the adhesive sheet is placed over it. As a result, there is no risk of deforming or damaging the powder compact during the process of placing it in a predetermined position. can be avoided. In addition, since the powder compact takes advantage of its good adhesive properties and facilitates highly accurate positioning, cut pieces with high dimensional accuracy can be obtained, and the problems of the conventional method are solved. Furthermore, in the case of cut pieces for forming ceramic capacitor chips, there is an advantage that excellent alignment of internal electrodes on the upper and lower sides of the laminate can be obtained.

However, with the fixing method using an adhesive sheet (adhesive tape or sheet) used in the conventional frame method, that is, an adhesive sheet with a simple pressure-sensitive adhesive layer provided on the support sheet, the obtained cut pieces cannot be deformed. It has been found that there is a new problem in that it is difficult to peel off from the adhesive sheet without causing damage, and it cannot be used as a practical technology as it is.

Means for Solving the Problems The present inventors have conducted further research in order to overcome the problems while taking advantage of the above-mentioned fixing method using adhesive sheets. As a result, they have developed an adhesive sheet that can be foamed. The present inventors have discovered that the object can be achieved by using the present invention, and have completed the present invention.

That is, the present invention has a foaming agent-containing pressure-sensitive adhesive layer for adhering and fixing a powder compact on one side of a support sheet,
A cut piece obtained by cutting a powder compact made of a double-sided adhesive sheet having a pressure-sensitive adhesive layer on the other side for adhering to a support base, and fixed to the foaming agent-containing pressure-sensitive adhesive layer. The present invention provides a foamed pressure-sensitive adhesive sheet which can be peeled off during foaming treatment.

By using a double-sided adhesive sheet, it is possible to cut the powder compact with the powder compact adhered and fixed to one side and the adhesive sheet fixed to the support via the other surface. A highly accurate cutting process is achieved.

On the other hand, by foaming the foaming agent-containing pressure-sensitive adhesive layer after the cutting process, the effective adhesive area can be reduced and the adhesive force to the cut pieces can be reduced, and re-adhesion of the cut pieces can be suppressed. This allows the cut pieces to be peeled off more easily than from the adhesive sheet. Furthermore, if the foaming treatment is performed so strongly that the foaming gas is ejected from the pressure-sensitive adhesive layer, the jet of foaming gas at the time of foaming will add a peeling action, making it easier to peel off the cut pieces. becomes.

Embodiment As shown in FIG. 1, the foamed pressure-sensitive adhesive sheet 2 of the present invention has a pressure-sensitive adhesive layer of 3.3 degrees on both sides of a support sheet 40, and has a small pressure-sensitive adhesive layer (one of which is foamed). The foaming agent-containing pressure-sensitive adhesive layer 3 is a powder compact, for example, an unsintered ceramic plate 1.
It is for pasting and fixing. The pressure sensitive adhesive layer 3° on the other side is for fixing the adhesive sheet 2 to a support such as a pedestal 5. By fixing the adhesive sheet 2 to the support base, when cutting the unsintered ceramic plate 1 adhered and fixed to the foaming agent-containing pressure-sensitive adhesive layer 3, the adhesive sheet 2 and the unsintered ceramic plate l This prevents the positional deviation of the cut piece l' from occurring, making it possible to form a cut piece l' with excellent dimensional accuracy. In addition, in automated manufacturing lines, etc., the foaming treatment of the foaming agent-containing pressure-sensitive adhesive layer 3 is generally performed with the adhesive sheet 2 peeled off from the support base. The pressure-sensitive adhesive layer 3' is preferably of a low adhesive strength type, such as a foaming type, a hardening type, or a low adhesive strength type, so that it can be easily peeled off. When a foaming agent is contained in both pressure-sensitive adhesive layers 3 and 3°, the foaming temperatures thereof should be different so that the foaming treatment on the pressure-sensitive adhesive layer 3° side can be performed at a lower temperature. is preferred.

As the pressure-sensitive adhesive, for example, known rubber-based or acrylic-based adhesives can be used.

More specifically, rubber polymers made of natural rubber, various synthetic rubbers, etc., alkyl ester polymers such as acrylic acid or methacrylic acid, or alkyl esters such as acrylic acid or methacrylic acid, for example, about 50 to 99.
5% by weight and about 50% of other unsaturated monomers copolymerizable therewith.
Acrylic polymers made of copolymers with ~0.5% by weight, etc., whose weight average molecular weight is 5,000 to 300,000
Examples include those in which 0 is used as a base polymer, and a crosslinking agent such as a polyisocyanate compound or an alkyl etherified melamine compound is blended therein as necessary.

In addition, when a crosslinking agent is used in combination, the amount thereof is generally about 0.1 to 10 parts by weight per 100 parts by weight of the base polymer.

Examples of the foaming agent to be added to the pressure-sensitive adhesive layer 3, or in some cases also to the pressure-sensitive adhesive layer 3', include ammonium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, and azide. Inorganic compounds such as azobisisobutyronitrile, azodicarbonamide, barium azodicarboxylate, toluenesulfonylhydrazide, diphenylsulfone-3,3'-disulfohydrazine, 4 .Hydrazine compounds such as 4'-oxybis(henzenesulfohydrazide) and allylbis(sulfohydrazide), semicarbazide compounds such as ρ-toluylenesulfonyl semicarbazide, 4,4''-oxybis(benzenesulfonyl semicarbazide), 5-morpholyl -1゜2.3.4-Triazole compounds such as thiatriazole, N-nitroso compounds such as N,N'-dinitrosopentamethylenetetramine, N,N'-dimethyl-N,N'-dinitrosoterephthalamide, etc. Examples include known foaming agents, such as organic compounds represented by compounds.In addition, foaming agents encapsulated in microcapsules are preferably used from the viewpoint of dispersibility in the pressure-sensitive adhesive. As the microencapsulated foaming agent, microspheres (F-30, F-50, F-7
Commercially available products such as 0; trade name, manufactured by Matsumoto Yushi Co., Ltd.) can be mentioned.

The amount of foaming agent blended is generally 5 to 300 parts by weight per 100 parts by weight of the above-mentioned base polymer, but as shown in Figure 5, foaming properties may vary depending on the type of foaming agent used, heating conditions, etc. (The volume of the pressure-sensitive adhesive layer 3 is approximately 20% due to foaming, and is not limited to this.)
It is appropriate to mix in an amount that is more than double the amount for the side to which the powder molded body is attached. Also, about 1 at 100-15oC
It is preferable to set the system so that the foaming treatment on the side to which the powder molded body is attached is completed by heating for about a minute.

As the support sheet 4, a relatively hard self-supporting film such as a polyester film or a polypropylene film is preferable from the viewpoint of strength, and the thickness thereof is 1O2.
~50hi is appropriate.

The foamed pressure-sensitive adhesive sheet of the present invention is used for producing cut pieces of powder compacts. There are no particular limitations on the powder compact to which the present invention can be applied. In the present invention, the powder compact is placed and fixed on a flat adhesive sheet, so internal electrodes are printed on the unsintered ceramic sheet formed by the sheet method described above. It is also preferably applied to ceramic plates, etc., which are laminated in sequence on a foaming agent-containing pressure-sensitive adhesive layer and pressed together to form a laminated plate for forming a ceramic capacitor. Can be done.

A representative example of a method for obtaining cut pieces of a powder compact using the foamed pressure-sensitive adhesive sheet of the present invention is the following method using an unsintered ceramic plate as an example.

That is, after the adhesive sheet 2 is fixed to the pedestal 5 via the pressure-sensitive adhesive layer 3' on a predetermined side thereof, the unsintered ceramic plate 1 is attached to the foaming agent-containing pressure-sensitive adhesive layer 3 of the adhesive sheet 2. (Fig. 1) and cut it to the specified size (Fig. 2).
figure). There are no particular limitations on the cutting means, and known means such as a rotary blade method or a cutting method using a knife may be used. When cutting, it is preferable to peel off the obtained cut piece l° (in order to do so, the foaming agent-containing pressure-sensitive adhesive layer 3 is also cut). However, in order to perform the subsequent foaming process smoothly, The support sheet 4 is not divided into parts (it is preferable to leave it in an integrated state, see FIG. 2).

Then, after peeling off the adhesive sheet 2 from the base 5, the foaming agent-containing pressure-sensitive adhesive layer 3 to which the cut piece l' is attached is subjected to foaming treatment (FIG. 3). As a result, the surface becomes uneven, the effective bonding area decreases, and the bonding force for a cut piece of 1° decreases. Furthermore, readhesion of the cut pieces l' is suppressed. In addition, during the foaming process, in order to inject the foaming gas onto the cut piece 1° during foaming and make it easier to peel off from the adhesive sheet, the foaming process should be done so strongly that the foaming gas is ejected from the pressure-sensitive adhesive layer (foaming process). You may.

Then, the adhesive sheet 2 is turned over and the cut pieces 1° on the pressure-sensitive adhesive layer 3 that have undergone the foaming process are forcibly and automatically peeled off (FIG. 4). In the present invention, sufficient peeling can be achieved with a peeling force that acts on the cut piece l° when the adhesive sheet 2 is reversed. Note that the method of forcibly peeling off the cut piece by contacting it is not preferable because it tends to deform or damage the cut piece.

In the manner described above, a cut piece of an unsintered ceramic plate is obtained.

Incidentally, when the pressure-sensitive adhesive sheet of the following example was applied to the above method, the results were as follows.

That is, 100 parts of butyl acrylate (parts by weight, the same applies hereinafter), 100 parts of a copolymer (weight average molecular weight approximately 800,000) consisting of 2 parts of acrylic acid, 2 parts of a polyisocyanate crosslinking agent.
A foaming agent-containing pressure-sensitive adhesive prepared by mixing 30 parts of microspheres (F-30), 5 parts of ammonia water (concentration 25%), and 10 parts of water using a solvent was prepared to a thickness of 100 parts.
Coating was applied to one side of a μm polyester film treated for easy adhesion to a dry thickness of 30μI, and the other side of the film was coated with a coating consisting of 100 parts of butyl acrylate, 15 parts of acrylonitrile, and 2 parts of acrylic acid. A pressure-sensitive adhesive prepared by mixing 100 parts of a polymer (with a weight average molecular weight of approximately 800,000), 10 parts of dioctyl phthalate, and 0.5 parts of a phosphoric acid ester surfactant using a solvent has a dry thickness of 1 Oum. A pressure-sensitive adhesive sheet was prepared by drying at 70°C for 5 minutes, and the resulting adhesive sheet was fixed on an aluminum base via the pressure-sensitive adhesive side, and then a foaming agent was applied. On top of the included pressure sensitive adhesive layer, a total of 6
It consists of 5 parts of BaTiO3 and CaTiO3, 15 parts of methyl methacrylate copolymer, and a total of 20 parts of doluol and butanol, and has a thickness of 0.05 m and a size of 1.
While printing internal electrodes at fixed positions on sheets for forming ceramic capacitors measuring 100 m x 100 m, 20 sheets were stacked one on top of the other and pressed with a force of 100 kl/cj to form an unsintered ceramic plate. Next, the ceramic plate was cut into chips with a size of 1.5 m x 2.5 m + square using a cutter, cutting down to the polyester film part. After cutting, the adhesive sheet was peeled off from the base and the cut pieces were kept attached at 130°C. The foam was heated and foamed for 1 minute.

Then, the foamed adhesive sheet was fed to an inversion type peeling device shown in FIG. 4, and the cut pieces were peeled off from the adhesive sheet.

The obtained cut pieces had excellent dimensional accuracy, no deformation or damage was observed, and the yield was excellent.

Effects of the Invention According to the foamed pressure-sensitive adhesive sheet of the present invention, cut pieces of a powder compact such as an unsintered ceramic plate can be removed from a pressure-sensitive adhesive layer without using a peeling means that would deform or damage the cut pieces. Since the powder can be peeled off, it is possible to fix the powder compact with an adhesive sheet and cut it.

As a result, based on the above-mentioned method, it is possible to easily hold the powder compact without deforming or damaging it, and with good positional accuracy. Furthermore, in addition to the fact that the time required for the foaming process is short, it is possible to efficiently produce cut pieces of powder compacts with high dimensional accuracy and high yield, which is the practical significance of the present invention. is big.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of a foam adhesive sheet with a ceramic plate adhered and fixed on one side and the other side fixed to a pedestal, Fig. 2 is an explanatory cross-sectional view of the ceramic plate cut away,
Fig. 3 is an explanatory cross-sectional view of the pressure-sensitive adhesive layer after foaming treatment, Fig. 4 is an explanatory cross-sectional view of the state in which the adhesive sheet is reversed and the cut pieces are peeled off, and Fig. 5 shows the foaming characteristics of the microspheres. This is the graph shown. 1: Unsintered ceramic plate 1°: Cut piece 2: Foamed adhesive sheet 3: Foaming agent-containing pressure-sensitive adhesive layer 3: Pressure-sensitive adhesive layer 4: Support sheet 5: Pedestal

Claims (1)

[Claims] 1. A pressure-sensitive adhesive layer containing a foaming agent for adhering and fixing the powder compact on one side of the support sheet, and a pressure-sensitive adhesive layer on the other side for adhering to the support base. A foamed adhesive which is made of a double-sided adhesive sheet having a double-sided adhesive sheet and is capable of peeling off cut pieces obtained by cutting a powder compact adhered and fixed to the above-mentioned foaming agent-containing pressure-sensitive adhesive layer under foaming treatment. sheet. 2. The pressure-sensitive adhesive sheet according to claim 1, which contains a microencapsulated foaming agent.