JP2005248094A - Cooling-and-peeling type self-adhesive composition, cooling-and-peeling type self-adhesive sheet, and manufacturing method of electronic component using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling-and-peeling type self-adhesive composition capable of being used in a wide temperature range, excellent in releasability after used in a temperature range of 80-100°C, and usable for a wide variety of applications. <P>SOLUTION: The cooling-and-peeling type self-adhesive composition contains a self-adhesive polymer as an available component, has an initial self-adhesive force of ≤0.2 N/25 mm in a temperature region of 0-30°C (an ordinary temperature region), has a self-adhesive force of ≥1 N/25 mm (self-adhesive force at high temperatures) in a temperature region of 80-100°C (a high-temperature region), and has a self-adhesive force (self-adhesive force after cooling) of ≤0.2 N/25 mm when cooled down to the ordinary temperature region from the high temperature region. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a pressure-sensitive adhesive sheet suitably used as a releasable pressure-sensitive adhesive sheet for temporarily fixing a workpiece that is a precursor of an electronic component in the production of electronic components including a multilayer ceramic capacitor. Adhesive strength is high in the high-temperature region, and the adherend can be securely fixed. In addition, the adhesive strength decreases after cooling from the high-temperature region to the normal temperature region, and the adherend is easily peeled off. The present invention relates to a cooling peelable pressure-sensitive adhesive composition, a cooling peelable pressure sensitive adhesive sheet, and an electronic component manufacturing method using the cooling peelable pressure sensitive adhesive sheet.

  In the manufacture of electronic components such as multilayer ceramic capacitors, when processing a workpiece, which is a precursor of an electronic component, the adhesive force is high, and the workpiece can be securely fixed. After the processed body is processed, a releasable pressure-sensitive adhesive sheet is used which has a reduced adhesive force and can easily peel the workpiece. Production of an electronic component using this releasable pressure-sensitive adhesive sheet is usually carried out in the following manner (here, an example in the case of producing a multilayer ceramic capacitor will be described).

  First, a slurry containing ceramic powder, a dispersion medium, a binder, and the like is thinned using a doctor blade method, a calendar method, or the like to obtain a ceramic green sheet. Next, after printing metal electrodes (internal electrodes) on the surface of the ceramic green sheet, a large number of these are laminated, thermocompression bonded, and integrated to form a metal electrode (a precursor of the multilayer ceramic capacitor) between layers ( A ceramic green sheet laminate (hereinafter simply referred to as “laminate”) in which the internal electrodes) are disposed is obtained.

  Furthermore, the laminate is temporarily fixed to a releasable adhesive sheet, and the workpiece is cut into a crumpled shape in a temporarily fixed laminate by a cutting device such as a dicer or a guillotine blade under high temperature conditions. After the dicing process is performed, the releasable pressure-sensitive adhesive sheet is peeled off to obtain a large number of chips (sometimes referred to as “workpieces”). Finally, the chip is fired, and a metal electrode (external electrode) is printed on the surface thereof, whereby a multilayer ceramic capacitor as a final product can be obtained.

  As the releasable pressure-sensitive adhesive sheet used in the above-mentioned applications, for example, it has a pressure-sensitive adhesive layer containing an ultraviolet curable oligomer, and the adhesive force of the pressure-sensitive adhesive layer is utilized by curing of the oligomer by ultraviolet irradiation. There has been proposed an ultraviolet curable pressure-sensitive adhesive sheet that lowers (see, for example, Patent Document 1).

  In addition, it has a pressure-sensitive adhesive layer containing heat-expandable microspheres, and makes use of the expansion of the heat-expandable microspheres by heating, and hence the reduction in the contact area between the adherend and the pressure-sensitive adhesive layer. A heat-peelable pressure-sensitive adhesive sheet that reduces the force has been proposed (see, for example, Patent Documents 2 to 5).

Furthermore, it has an adhesive layer containing an adhesive polymer whose main chain and / or side chain is a crystalline polymer, and reduces the adhesive force of the adhesive layer by utilizing crystallization of the crystalline polymer by cooling. A cooling peelable pressure-sensitive adhesive sheet has also been proposed (see, for example, Patent Document 6).
JP-A-9-291258 JP-A-11-302614 JP 2000-351947 A JP 2002-69422 A JP 2003-160765 A JP-A-9-251923

  All of these removable pressure-sensitive adhesive sheets have sufficient adhesive strength when used, but can reduce the adhesive strength after use and can be peeled off without leaving the adhesive on the adherend. It is supposed to be possible.

  However, after the ultraviolet curable pressure-sensitive adhesive sheet is used at a high temperature, the heat-peelable pressure-sensitive adhesive sheet is caused by the contraction of the microsphere due to the unevenness of the expansion of the thermally expandable microsphere. When re-bonding occurs, there are cases where the decrease in adhesive strength is not sufficient, and there is a problem in terms of peelability after use. If the peelability after use is inferior, the adherend may be damaged at the time of peeling, or the adhesive layer remains on the adherend until it does not break (often referred to as “glue residue”), and the firing step This is not preferable in that it causes blocking, voids, cracks, and the like, leading to a decrease in reliability and yield of the final product.

  This problem was particularly acute when the final product was a multilayer ceramic capacitor. That is, when the final product is a multilayer ceramic capacitor, the adherend is a ceramic green sheet laminate, so that the surface is rough and it is difficult to obtain good peelability. Is unfired and is in a state where the layers are not sufficiently bonded, and therefore, delamination may occur.

  In addition, UV curable pressure sensitive adhesive sheets and heat-peelable pressure sensitive adhesive sheets require UV irradiation and high temperature heating when reducing the adhesive strength, and UV or heat is not only applied to the adhesive layer, but also to adherends and pressure sensitive adhesive sheets. This also acts on the substrate. Therefore, there is a risk that the adherend or the like may have adverse effects such as deterioration or deformation. In particular, when manufacturing a multilayer ceramic capacitor using a heat-peelable pressure-sensitive adhesive sheet, the final product after firing has sufficient strength and hardness due to the binder volatilizing from the laminate before firing. There was a case where troubles such as inability to occur occurred.

  On the other hand, the cooling peelable pressure sensitive adhesive sheet described in Patent Document 6 uses polymer crystallization to reduce the adhesive strength of the pressure sensitive adhesive layer. Therefore, the ultraviolet curable pressure sensitive adhesive sheet or the heat peelable pressure sensitive adhesive sheet is used. Unlike a sheet, it is not necessary to irradiate with ultraviolet rays or heat at high temperature when reducing the adhesive strength. Therefore, ultraviolet rays and heat do not adversely affect the workpiece and the like, and there is an advantage that it can be reused even after the adherence is peeled off once the adhesive force is reduced. .

  However, the cooling peelable pressure-sensitive adhesive sheet described in Patent Document 6 has a problem that the peelability after use in a temperature range of 80 to 100 ° C. may be inferior. That is, after processing in the temperature range of 80 to 100 ° C. using the above-described cooling peelable pressure-sensitive adhesive sheet, even if it is cooled to room temperature, the decrease in adhesive force is not sufficient, and the elastic modulus accompanying the temperature increase Since the decrease is large, the peelability to the rough surface is inferior, and the adherend may be damaged or the adhesive may remain as in the case of the ultraviolet curable pressure sensitive adhesive sheet or the heat peelable pressure sensitive adhesive sheet.

  These problems are not preferable in that the use temperature range and application of the releasable pressure-sensitive adhesive sheet are limited. In particular, in the manufacture of multilayer ceramic capacitors, the binder contained in the multilayer body has been softened in order to prevent the multilayer body from cracking due to the insertion of a dicer or guillotine blade, and to support the multilayering of multilayer ceramic capacitors. Dicing is being performed at a high temperature of about 80 to 100 ° C., and these problems may become apparent.

  As described above, at present, there is little adverse effect on the adherend due to ultraviolet rays or heat, and it can be reused even after the adherend has been peeled off once the adhesive force has been reduced. The releasable pressure-sensitive adhesive sheet has a wide use temperature range, excellent peelability after use in a temperature range of 80 to 100 ° C., excellent peelability on a rough surface, and can be used for various purposes. It has not been disclosed yet, and there is a strong demand from the industry to create such a releasable adhesive sheet.

  The present invention has been made in order to solve the above-described problems of the prior art, and has less adverse effects on the adherend due to ultraviolet rays or heat, and after the adherend is peeled off once the adhesive force is reduced. In addition to being reusable, it has a wide operating temperature range, excellent peelability after use in a temperature range of 80 to 100 ° C., and can be used for various applications. The present invention provides a cooling peelable pressure-sensitive adhesive composition, a cooling peelable pressure sensitive adhesive sheet, and an electronic component manufacturing method using the same.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors include an adhesive polymer as an active ingredient, and an initial adhesive force in a temperature range of 0 to 30 ° C. (normal temperature range) is 0.2 N / 25 mm or less. The adhesive strength (high temperature adhesive strength) in the temperature range (high temperature range) of 80 to 100 ° C. is 1 N / 25 mm or more, and the adhesive strength (cooling adhesive strength) after cooling from the high temperature range to the normal temperature range is The present invention was completed by conceiving that the above-mentioned problems could be solved by a cooling peelable pressure-sensitive adhesive composition having a novel configuration of 0.2 N / 25 mm or less. That is, according to this invention, the following cooling peeling type adhesive compositions, the cooling peeling type adhesive sheet, and the manufacturing method of an electronic component using the same are provided.

[1] An adhesive polymer is included as an active ingredient, and an initial adhesive force in a temperature range of 0 to 30 ° C. (normal temperature range) is 0.2 N / 25 mm or less, and a temperature range of 80 to 100 ° C. (high temperature range) ) Is an adhesive strength (adhesive strength at high temperature) of 1 N / 25 mm or more, and an adhesive strength after cooling from the high temperature region to the normal temperature region (adhesive strength after cooling) is 0.2 N / 25 mm or less. Adhesive composition.

[2] The constituent monomer as a main component is an acrylic resin having a weight average molecular weight (Mw) of 600,000 or more, which is an acrylic acid or methacrylic acid ester monomer in which an alkyl group having 1 to 4 carbon atoms is ester-bonded, A cooling release pressure-sensitive adhesive composition containing a temperature-sensitive adhesive polymer having a glass transition temperature (Tg) in a temperature range of −10 to 30 ° C.

[3] The temperature-sensitive adhesive polymer and at least a part of the constituent monomers are acrylic resin or acrylic resin in which an alkyl group having 6 to 8 carbon atoms is ester-bonded, and the alkyl. An active ingredient is an adhesive polymer composed of a low-polarity adhesive polymer whose group polarity is lower than that of the temperature-sensitive adhesive polymer, and a crosslinking agent capable of crosslinking between these polymers. In addition, the cooling release pressure-sensitive adhesive composition according to [2] above, which contains a crosslinked polymer derived from the active ingredient.

[4] In the adhesive polymer, the constituent monomer as a main component is an acrylic acid or methacrylic acid ester monomer in which an alkyl group having 1 to 4 carbon atoms is ester-bonded, and the weight average molecular weight (Mw) is 600,000 or more The cooling peelable pressure-sensitive adhesive composition according to the above [1], which comprises a temperature-sensitive adhesive polymer having a glass transition temperature (Tg) in the temperature range of −10 to 30 ° C.

[5] The adhesive polymer is made of an acrylic resin in which at least a part of the constituent monomer is an acrylic acid or methacrylic acid ester monomer in which an alkyl group having 6 to 8 carbon atoms is ester-bonded, and the polarity of the alkyl group The cooling peelable pressure-sensitive adhesive composition according to [4] above, further comprising a low-polarity adhesive polymer that is lower than the temperature-sensitive adhesive polymer.

[6] Cooling provided with a film-like or sheet-like base material, and provided with an adhesive layer containing the cooling release adhesive composition according to any one of the above [1] to [5] on at least one surface thereof Peelable adhesive sheet.

[7] The pressure-sensitive adhesive layer has a concentration gradient that distributes the low-polar pressure-sensitive adhesive polymer or the cross-linked polymer cross-linked by the cross-linking agent so that the concentration on the surface of the pressure-sensitive adhesive layer is higher than that on the substrate side. The cooling peelable pressure-sensitive adhesive sheet according to the above [6], which is formed.

[8] A workpiece, which is a precursor of an electronic component, is temporarily fixed to a releasable pressure-sensitive adhesive sheet, and the temporarily fixed workpiece is processed, and then the releasable pressure-sensitive adhesive sheet is peeled off. An electronic component manufacturing method comprising a step of obtaining a processed body, wherein the cooling-peelable pressure-sensitive adhesive sheet according to the above [6] or [7] is used as the re-peelable pressure-sensitive adhesive sheet. .

[9] The workpiece is a ceramic green sheet laminate in which metal electrodes are disposed between layers, which is a precursor of a multilayer ceramic capacitor, and the machining is performed by cutting the workpiece into a grid shape. The method for manufacturing an electronic component according to the above [8], which is a dicing process to make a small piece.

  The cooling peelable pressure-sensitive adhesive composition and the cooling peelable pressure-sensitive adhesive sheet of the present invention have little adverse effect on the adherend due to ultraviolet rays or heat, and are reused even after the adherend is peeled off once the adhesive force is reduced. In addition to being able to be used, it has a wide operating temperature range, excellent peelability after use in a temperature range of 80 to 100 ° C., and can be used for various purposes, compared to conventional products. Thus, there is an advantageous effect.

  Hereinafter, the cooling peelable pressure-sensitive adhesive composition of the present invention, the cooling peelable pressure sensitive adhesive sheet, and the best mode for carrying out the method for producing an electronic component using the same will be specifically described. It is not limited to the form.

[1] Cooling and peeling type pressure-sensitive adhesive composition The cooling and peeling type pressure-sensitive adhesive composition of the present invention contains an adhesive polymer as an active ingredient and has an initial adhesive strength of 0 to 30 ° C in a temperature range (normal temperature range). Adhesive strength (adhesive strength at high temperature) in a temperature range of 80 to 100 ° C. (high temperature range) is 1 N / 25 mm or higher and adhesive strength after cooling from a high temperature range to a normal temperature range (after cooling) It is a cooling peelable pressure-sensitive adhesive composition having an adhesive strength of 0.2 N / 25 mm or less. Such a cooling peelable pressure-sensitive adhesive composition exhibits excellent high-temperature adhesive strength, so that the adherend can be reliably fixed in the high-temperature region, and the adhesive strength after cooling is sufficiently low, so that the high-temperature region It is possible to easily peel off the adherend even after the processing at, and it is possible to effectively prevent the damage to the adherend and the problem of adhesive residue.

  The composition of the cooling peelable pressure-sensitive adhesive composition of the present invention is not particularly limited as long as it has the above-mentioned properties. However, the pressure-sensitive adhesive polymer contains at least a temperature-sensitive pressure-sensitive adhesive polymer, and other components may be used as desired. Such an adhesive polymer, for example, one containing a low-polar adhesive polymer that is lower than a temperature-sensitive adhesive polymer is preferably used. More specifically, a thermosensitive adhesive polymer, a low-polar adhesive polymer, and a crosslinking agent capable of cross-linking between these polymers are used as active ingredients, and the cross-linking One example is a cooling peelable pressure-sensitive adhesive composition containing molecules. Hereinafter, each component will be described.

(1) Temperature-sensitive adhesive polymer In the present specification, the term “temperature-sensitive adhesive polymer” refers to a temperature-sensitive adhesive force that changes depending on a temperature change, more specifically, a temperature rise. The adhesive polymer which has the characteristic that the adhesive force with respect to a to-be-adhered body raises in connection with is shown. The “temperature-sensitive adhesive polymer” that is an active ingredient of the cooling release adhesive composition of the present invention is acrylic acid in which the constituent monomer as the main component is ester-bonded with an alkyl group having 1 to 4 carbon atoms. Or it is an adhesive polymer which consists of acrylic resin which is a methacrylic acid ester monomer, and has the glass transition temperature (it may be abbreviated as "Tg") in the range of -10-30 degreeC.

  In the present invention, an “acrylic resin” is used as a base resin for the “temperature-sensitive adhesive polymer”. In general, rubber-based resins, acrylic resins, silicone-based resins, and the like are known as adhesive polymers, but acrylic resins are preferable in that the glass transition temperature can be easily controlled in a desired temperature range.

  In the present specification, the term “acrylic resin” means a resin containing, as a constituent monomer, acrylic acid, methacrylic acid, or an ester thereof, acrylonitrile, acrylamide or the like (hereinafter referred to as “acrylic monomer”). In addition, not only homopolymers (homopolymers) of these constituent monomers but also copolymers (copolymers) are included. However, the “temperature-sensitive adhesive polymer” referred to in the present invention needs to contain an acrylic acid or methacrylic acid ester monomer in which an alkyl group having 6 to 8 carbon atoms is ester-bonded to at least a part of the constituent monomers. To do.

  In addition, the “acrylic resin” only needs to contain an acrylic monomer as a constituent monomer, and includes other constituent monomers (non-acrylic monomers) as long as the effects of the present invention are not impaired. Also good. Although it does not specifically limit about the kind of other structural monomer, For example, styrene, vinyl acetate, or N-vinyl pyrrolidone etc. are mentioned.

  The “temperature-sensitive adhesive polymer” referred to in the present invention is an adhesive polymer having a glass transition temperature in the temperature range of −10 to 30 ° C., and the temperature sensitivity is increased by freezing the polymer based on the glass transition phenomenon. It is a temperature sensitive adhesive polymer. Such an adhesive polymer becomes rubbery and softens in the temperature range above the glass transition temperature, and exhibits high adhesive strength, while the polymer freezes and cures in the temperature range below the glass transition temperature. descend. Therefore, the temperature sensitivity that the adhesive force changes depending on the temperature change is exhibited.

  Having a glass transition temperature in the temperature range of −10 to 30 ° C. is to reduce the adhesive force in the normal temperature range where the adherend is adhered, while temporarily fixing the adherend to process it 80 to This is because a high adhesive force is expressed in a temperature range of 100 ° C. (hereinafter referred to as “high temperature range”).

  This utilizes the property that an adhesive polymer having a glass transition temperature exhibits an adhesive force for the first time at a temperature of glass transition temperature + 30 ° C. That is, if a glass transition temperature is used in a temperature range of −10 to 30 ° C., the adhesive strength is not yet expressed in the normal temperature range where the adherend is stuck, and the adhesive strength is kept low. Can do. Moreover, since the adhesive force developed at the glass transition temperature + 30 ° C. increases as the temperature rises, it exhibits a high adhesive force in a high temperature region where the adherend is temporarily fixed and processed.

  On the other hand, when the glass transition temperature is less than −10 ° C., the polymer is not frozen even if the temperature is lowered to the room temperature region after processing in the high temperature region, and it may be difficult to reduce the adhesive strength. It is not preferable in that there is. Moreover, when it exceeds 30 degreeC, softening does not advance also in a high temperature area | region, and it is not preferable at the point which may become difficult to exhibit sufficient adhesiveness.

  By the way, it is known that the glass transition temperature of the acrylic resin is strongly influenced by the carbon number of the alkyl group ester-bonded to the carboxyl group of acrylic acid or methacrylic acid. Specifically, as the carbon number of the alkyl group increases, the glass transition temperature decreases, the alkyl ester having 8 to 10 carbon atoms exhibits the lowest glass transition temperature, and the carbon number of the alkyl group further increases. Then, the glass transition temperature tends to rise again. The “temperature-sensitive adhesive polymer” referred to in the present invention contains an acrylic acid or methacrylic acid ester monomer in which a relatively short chain alkyl group having 1 to 4 carbon atoms is ester-bonded as a main component of the constituent monomer. Thus, the glass transition temperature (Tg) is controlled to be in the normal temperature region. The “main component” in the present invention means a constituent monomer that occupies 50% by mass or more with respect to the total constituent monomers.

  Examples of the alkyl group having 1 to 4 carbon atoms include 1-propyl group (n-propyl group), 1-methylethyl group (iso-propyl group), 1-butyl group (n-butyl group), and 2-methylpropyl group. (Iso-butyl group), 1-methylpropyl group (sec-butyl group), 1,1-dimethylethyl group (tert-butyl group) and the like. Accordingly, acrylic acid or methacrylic acid ester monomers having an ester bond with a relatively short chain alkyl group having 1 to 4 carbon atoms include methyl ester, ethyl ester, 1-propyl ester (n-propyl ester) of acrylic acid or methacrylic acid. Ester), 1-methylethyl ester (iso-propyl ester), 1-butyl ester (n-butyl ester), 2-methylpropyl ester (iso-butyl ester), 1-methylpropyl ester (sec-butyl ester), 1,1-dimethylethyl ester (tert-butyl ester) and the like can be mentioned.

  In addition, the polymer used for the cooling peelable pressure-sensitive adhesive sheet described in Patent Document 6 is also acrylic acid or methacrylic acid in which an alkyl group is ester-bonded, similarly to the “temperature-sensitive adhesive polymer” referred to in the present invention. Although it is acrylic resin which uses an acid ester monomer as a constituent monomer, it differs in the following points.

  The polymer described in Patent Document 6 is a crystalline polymer having a melting point in the vicinity of the normal temperature region. In the temperature region above the melting point, the polymer loses rigidity and softens and exhibits adhesive strength, whereas in the temperature region below the melting point, the polymer Crystallizes and cures, reducing adhesive strength. Therefore, the temperature sensitivity that the adhesive force changes depending on the temperature change is exhibited.

  As described above, the adhesive polymer of the type in which the temperature sensitivity is exhibited by crystallization of the polymer has a preferable characteristic that it has excellent responsiveness due to the phenomenon of crystallization being sensitive to temperature change. However, after processing in a high temperature region, even if it is cooled to a normal temperature region, the decrease in adhesive force is not sufficient, and since the decrease in elastic modulus with a rise in temperature is large, the peelability to a rough surface is poor, There is a tendency that the adherend is damaged and adhesive residue is generated.

  In contrast, the “temperature-sensitive adhesive polymer” referred to in the present invention is a type of temperature-sensitive adhesive polymer that exhibits temperature sensitivity due to freezing of the polymer due to the glass transition phenomenon. Although it is somewhat inferior, it has a feature of exhibiting high adhesive force in a relatively wide temperature range, and exhibits high adhesive force even in a high temperature region. Therefore, the problem that the adhesive polymer of the type in which the temperature sensitivity is manifested by crystallization of the polymer has a narrow use temperature range and its use is limited is effectively prevented.

  In order to ensure the crystallinity of the polymer described in Patent Document 6, most of the monomer is composed of an acrylic acid or methacrylic acid ester monomer in which a long-chain alkyl group having 16 to 18 carbon atoms is ester-bonded. However, the “temperature-sensitive adhesive polymer” referred to in the present invention has an ester bond with a relatively short chain alkyl group having 1 to 4 carbon atoms as the main component of the constituent monomer. It is sufficient if it contains acrylic acid or methacrylic acid ester monomers, and it is different in that it does not need to be a crystalline polymer.

  The “temperature-sensitive adhesive polymer” preferably has a functional group capable of reacting with a crosslinking agent (hereinafter referred to as “reactive functional group”) in at least a part of the constituent monomers. When this reactive functional group reacts with a crosslinking agent to form a crosslinked polymer, it is possible to exhibit sufficient adhesive strength in a high temperature region and excellent peelability after cooling.

  The reactive functional group only needs to be contained in at least a part of the constituent monomers, and the monomers do not need to be acrylic monomers. That is, the reactive functional group may be included in the acrylic monomer itself, or may be included in a non-acrylic monomer copolymerized with the acrylic monomer.

  As the reactive functional group, a carboxyl group, a hydroxyl group, an amino group, or the like is known, but is a hydroxyl group in that the adhesive strength after cooling is low and the removability after processing in a high temperature region is excellent. It is preferable. Examples of the acrylic monomer having a hydroxyl group as a reactive functional group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, and 4-hydroxybutyl acrylate. , 4-hydroxybutyl methacrylate and the like.

  The “temperature-sensitive adhesive polymer” is preferably an acrylic resin having a weight average molecular weight (sometimes abbreviated as “Mw”) of 600,000 or more, and is in the range of 600,000 to 2,000,000. It is more preferable that it is an acrylic resin, and it is especially preferable that it is an acrylic resin in the range of 600,000 to 1,500,000. If the weight average molecular weight is less than the above range, it is not preferable in that the adhesive strength may be lowered in the high temperature region, and if it exceeds the above range, the peelability after use in the high temperature region tends to be insufficient. It is not preferable.

  The weight average molecular weight (Mw) is determined when polymerizing the “temperature-sensitive adhesive polymer” (by appropriately controlling the type and amount of the chain transfer agent, the molar ratio of the monomer to the polymerization initiator, etc. In addition, a commercially available adhesive polymer having a desired weight average molecular weight may be appropriately selected and used.

  The “temperature-sensitive adhesive polymer” can be obtained, for example, by a method of radical polymerization of the above-described acrylic monomer (non-acrylic monomer as required). The polymerization method is not particularly limited, and a conventionally known polymerization method such as an emulsion polymerization method, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or a photopolymerization method can be suitably used.

(2) Low-polarity adhesive polymer “Low-polarity adhesive polymer” which is an active ingredient of the cooling peelable adhesive composition of the present invention has an alkyl group having 6 to 8 carbon atoms as a constituent monomer. It is an adhesive polymer made of an acrylic resin which is an ester-bonded acrylic acid or methacrylic acid ester monomer, and the polarity of the alkyl group is lower than that of the above-mentioned “temperature-sensitive adhesive polymer”.

  The resin used as the base of the “low-polar adhesive polymer” referred to in the present invention is an “acrylic resin”, and its definition (type of constituent monomers, preferred acrylic monomer content, etc.) is “temperature-sensitive type”. The same as “adhesive polymer”. However, the difference is that the polarity of the alkyl group of the acrylic acid or methacrylic acid ester monomer forming a part of the constituent monomer is lower than that of the above-mentioned “temperature-sensitive adhesive polymer”.

  In the “low-polarity adhesive polymer” referred to in the present invention, the polarity of the alkyl group of the acrylic acid or methacrylic acid ester monomer constituting a part of the constituent monomer is lower than that of the above-mentioned “temperature-sensitive adhesive polymer”. The reason is that the above-mentioned “temperature-sensitive adhesive polymer” is not sufficient to improve the peelability after use in a high temperature region.

  This utilizes the property that the adhesive force of the adhesive polymer to the adherend varies depending on the polarity of the alkyl group of the acrylic acid or methacrylic acid ester monomer. The above-mentioned “temperature-sensitive adhesive polymer” has a relatively high polarity of short chain alkyl groups ester-bonded to acrylic acid or methacrylic acid, so that it is like a green sheet laminate that is a precursor of a multilayer ceramic capacitor. The affinity between the adherend made of ceramic and relatively high polarity is high. Therefore, although it has a preferable characteristic that it exhibits high adhesive strength in a high temperature range and a wide use temperature range, it alone is not sufficient in peelability after use in a high temperature range, and problems such as damage to the adherend and adhesive residue May occur. Therefore, after using in a high temperature region by containing an appropriate amount of the “low-polar adhesive polymer” referred to in the present invention and reducing the polarity of the pressure-sensitive adhesive composition (particularly the contact portion with the adherend). The peelability can be improved, and problems such as breakage of the adherend and adhesive residue can be effectively suppressed.

  To make the polarity of the alkyl group of the acrylic acid or methacrylic acid ester monomer that constitutes a part of the constituent monomer lower in the “low-polar adhesive polymer” compared to the above “temperature-sensitive adhesive polymer” It is necessary that at least a part of the constituent monomer is an acrylic acid or methacrylic acid ester monomer in which an alkyl group having 6 to 8 carbon atoms is ester-bonded.

  Examples of the alkyl group having 6 to 8 carbon atoms include 1-hexyl group (n-hexyl group), 1-heptyl group (n-heptyl group), 1-octyl group (n-octyl group), 6-methylheptyl group ( iso-octyl group), 2-ethylhexyl group and the like. Accordingly, acrylic acid or methacrylic acid ester monomers having an ester bond with an alkyl group having 6 to 8 carbon atoms include 1-hexyl ester (n-hexyl ester) and 1-heptyl ester (n-heptyl ester) of acrylic acid or methacrylic acid. Ester), 1-octyl ester (n-octyl ester), 6-methylheptyl ester (iso-octyl ester), 2-ethylhexyl ester and the like. Among them, it is preferable to use 2-ethylhexyl ester which is inexpensive and easily available. The acrylic acid or methacrylic acid ester monomer having an ester bond with an alkyl group having 6 to 8 carbon atoms is contained in an amount of 40% by mass or more, preferably 50 to 98% by mass with respect to all constituent monomers in order to ensure the effect. It is preferable that

  As already described, the glass transition temperature of the acrylic resin is strongly influenced by the carbon number of the alkyl group ester-bonded to the carboxyl group of acrylic acid or methacrylic acid. As in the “low polarity adhesive polymer” referred to in the present invention, an acrylic resin in which at least a part of the constituent monomer is an acrylic acid or methacrylic acid ester monomer in which an alkyl group having 6 to 8 carbon atoms is ester-bonded, It has a glass transition temperature in a temperature range of −50 to −80 ° C. (hereinafter referred to as “low temperature range”).

  The “low-polar adhesive polymer” is also preferably one having a reactive functional group in at least a part of the constituent monomers, similarly to the “temperature-sensitive adhesive polymer”. However, the difference is that the weight average molecular weight (Mw) is lower than the above-mentioned “temperature-sensitive adhesive polymer”.

  The “low-polar adhesive polymer” is preferably an acrylic resin having a weight average molecular weight (Mw) of 100,000 or more and less than the molecular weight of the temperature-sensitive adhesive polymer used in combination. When the weight average molecular weight (Mw) is less than 100,000, the low-polar adhesive polymer easily moves to the adherend. For example, when the adherend is a precursor of an electronic component, It is not preferable in that it may adversely affect its electrical characteristics. If the molecular weight exceeds the molecular weight of the temperature-sensitive adhesive polymer used in combination, it will be difficult to distribute on the surface of the adhesive layer, effectively preventing adhesive residue. This is not preferable in that there is a possibility that it may not be possible.

  The weight average molecular weight (Mw) can be adjusted within the above range by the same method as for the “temperature-sensitive adhesive polymer”. The “low-polar adhesive polymer” can be produced according to the production method (polymerization method) described in the section of “temperature-sensitive adhesive polymer”.

(3) Crosslinking agent The “crosslinking agent” referred to in the present invention forms a crosslinked polymer by crosslinking between the previously described “temperature-sensitive adhesive polymer” and “low-polar adhesive polymer”. It means the substance to get. This “cross-linking agent” reacts with the reactive functional group of “temperature-sensitive adhesive polymer” or “low-polar adhesive polymer” to form a crosslinked polymer, thereby providing sufficient adhesive strength in a high temperature region. It becomes possible to exhibit excellent peelability after cooling.

  Generally, as the crosslinking agent, an isocyanate crosslinking agent, a metal chelate crosslinking agent, an epoxy crosslinking agent, or the like is known. In the present invention, an isocyanate crosslinking agent can be preferably used.

  As an isocyanate type crosslinking agent, a conventionally well-known isocyanate type crosslinking agent, for example, a polyvalent isocyanate compound, its oligomer, a prepolymer, etc. can be used conveniently. Examples of the polyvalent isocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylene diisocyanate, diphenylmethane-4,4′-diisocyanate, diphenylmethane. Examples include -2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, and lysine isocyanate. Among them, hexamethylene diisocyanate trimer (for example, trade name: Takenate D-170N, manufactured by Mitsui Takeda Chemical Co., Ltd.) can be preferably used. This cross-linking agent is preferable in that it has the effect of imparting excellent removability and heat resistance. In addition, a "crosslinking agent" may be used independently and may be used in combination of 2 or more type.

(4) Cooling and peeling type pressure-sensitive adhesive composition As the cooling and peeling type pressure-sensitive adhesive composition of the present invention, a temperature-sensitive pressure-sensitive adhesive polymer and a crosslinking agent in an amount of 0.3 to 1.5 parts by mass. A mixture containing the mixture as a raw material and containing a crosslinked polymer derived from these raw materials, or a temperature-sensitive adhesive polymer and a low-polar adhesive polymer has a mass ratio of 99.5: 0.5. When the total mass of the temperature-sensitive adhesive polymer and the low-polar adhesive polymer is 100 parts by mass, the crosslinking agent is 0.3- Examples include a mixture containing 1.5 parts by mass of a raw material and containing a crosslinked polymer derived from these raw materials. However, the latter composition is preferred as the cooling peelable pressure-sensitive adhesive composition used in the method for producing an electronic component.

  By including a temperature-sensitive adhesive polymer and a cross-linking agent (if necessary, a low-polar adhesive polymer) in the above ratio, the initial adhesive force in the normal temperature region is 0.2 N / 25 mm or less, and the high temperature Adhesive strength in the region (adhesive strength at high temperature) is 1 N / 25 mm or more, and the adhesive strength after cooling from the high temperature region to the normal temperature region (adhesive strength after cooling) is 0.2 N / 25 mm or less. It can be a composition. In particular, in the manufacture of electronic components, the initial adhesive strength in the normal temperature region is 0.05 N / 25 mm or less, the adhesive strength at high temperature is 1 N / 25 mm or more, and the adhesive strength after cooling is 0.2 N / 25 mm or less. The cooling peelable pressure-sensitive adhesive composition can be suitably used.

  In addition, when the low-polar adhesive polymer is included in the low-polar adhesive polymer, if the proportion of the low-polar adhesive polymer is less than the above range, the peelability after use in the high-temperature region is inferior, and the adhesive residue or adherend It is not preferable in that a problem such as breakage may occur, and if it exceeds the above range, it is not preferable in that adhesive strength in a high temperature region may be reduced. Moreover, when the ratio of a crosslinking agent is less than the said range, it is unpreferable at the point which peelability after using in a high temperature area | region tends to become inadequate. Moreover, when the ratio of a low polar adhesive polymer exceeds the said range, it is unpreferable at the point that adhesive force may fall in a high temperature area | region.

  The cooling peelable pressure-sensitive adhesive composition of the present invention, unlike other re-peelable pressure sensitive adhesives such as UV curable and heat peelable, has little adverse effect on adherends due to ultraviolet rays or heat, and once reduces the adhesive strength. Even after the adherend is peeled off, it can be reused. And, the cooling peelable pressure-sensitive adhesive composition of the present invention has a wide operating temperature range, unlike the type of cooling peelable type in which temperature sensitivity is manifested by crystallization of the polymer. And can be used for various purposes.

[2] Cooling peeling type pressure sensitive adhesive sheet The cooling peeling type pressure sensitive adhesive composition of the present invention comprises a film-like or sheet-like base material, and includes the cooling peeling type pressure sensitive adhesive composition of the present invention on at least one surface thereof. An adhesive layer is provided. However, the cooling peelable pressure-sensitive adhesive composition itself of the present invention can be formed into a film or sheet to form a cooling peelable pressure sensitive adhesive sheet.

  The cooling peeling type adhesive sheet of this invention is equipped with a base material and an adhesion layer as the component. Hereinafter, each element will be described.

(1) Base Material The “base material” referred to in the present invention is a member for supporting the adhesive layer and exhibits a film shape or a sheet shape. In the present specification, the term “film shape or sheet shape” means a thin film shape or a thin plate shape, and usually 12 to 250 μm.

  It does not specifically limit about the constituent material of a base material, According to the use of a cooling peeling type adhesive sheet, it can select suitably from the materials conventionally used as a base material for adhesive sheets. Specifically, synthetic resins such as polyethylene terephthalate, polyethylene naphthalate, polyethylene, polypropylene, polycarbonate, triacetyl cellulose, cellophane, polyimide, polyamide, polyphenylene sulfide, polyetherimide, polyethersulfone, aromatic polyamide, or polysulfone, It can be selected from glass, metal, ceramic and the like. The base material may be transparent or colored. Coloring can be performed by a method of blending various pigments or dyes into the constituent material of the substrate. The surface of the substrate is not limited to a smooth surface, and the surface may be processed into a mat shape.

  Even if a base material contains the conventionally well-known additive in the constituent material, specifically, a heat stabilizer, an oxidation stabilizer, a weather stabilizer, a ultraviolet absorber, an antistatic agent, etc. Good. Moreover, it is preferable to use what gave surface treatment for the purpose of improving adhesiveness with an adhesion layer. Examples of the surface treatment include discharge treatment such as corona discharge treatment and glow discharge treatment, plasma treatment, flame treatment, ozone treatment, ionizing active ray treatment such as ultraviolet treatment, electron beam treatment and radiation treatment, sand mat treatment and anchor treatment, Examples thereof include surface roughening treatment such as hairline treatment, chemical treatment, and easy adhesion layer coating treatment.

(2) Adhesive layer The “adhesive layer” referred to in the present invention is a layer formed so as to cover at least one surface of a substrate, and includes an adhesive composition exhibiting adhesiveness to an adherend. It is a waste.

  As the pressure-sensitive adhesive composition contained in the “pressure-sensitive adhesive layer”, it is necessary to use the cooling peelable pressure-sensitive adhesive composition of the present invention already described. Thereby, there is little adverse effect on the adherend due to ultraviolet rays or heat, etc. In addition to being able to be reused even after the adherence has been peeled off once the adhesive force is reduced, the use temperature range is wide, The releasable pressure-sensitive adhesive sheet is excellent in releasability after use in a high temperature region and can be used for various applications, and has an advantageous effect as compared with the conventional one.

  The thickness of the adhesive layer is not particularly limited, but is preferably 2 to 100 μm, more preferably 5 to 60 μm, and particularly preferably 10 to 30 μm. When the thickness of the pressure-sensitive adhesive layer is less than the above range, it is not preferable in that sufficient adhesive force to the adherend may not be obtained.

  When the cooling peelable pressure-sensitive adhesive composition of the present invention includes a low-polarity adhesive polymer or a crosslinked polymer that is crosslinked with a crosslinking agent, the adhesive layer is a low-polarity adhesive polymer, or a crosslinked high-polymer. It is preferable that a concentration gradient is formed so that molecules are distributed so that the concentration on the surface side of the adhesive layer is higher than that on the substrate side.

  As a method for forming the concentration gradient as described above, a pressure-sensitive adhesive polymer, a low-polar adhesive polymer, and an adhesive layer-forming coating solution obtained by dissolving or mixing a crosslinking agent in a solvent are used. Method for forming an adhesive layer, or forming a first adhesive layer containing a temperature-sensitive adhesive polymer and covering the surface with a low-polar adhesive polymer, a crosslinking agent, and a low-polar adhesive high Examples thereof include a method of forming a second adhesive layer containing a molecule and a crosslinking polymer derived from a crosslinking agent.

  The above configuration distributes the low-polar adhesive polymer having a low affinity with the ceramic at a high concentration on the contact surface side with the adherend, and thus can effectively prevent adhesive residue. it can. However, when the latter method is employed, it is preferable to make the second adhesive layer thinner than the first adhesive layer from the viewpoint of securing the adhesive strength in the high temperature region. Specifically, it is preferable that the first adhesive layer has a thickness of 5 to 60 μm and the second adhesive layer has a thickness of about 0.1 to 10 μm.

(3) Cooling Peeling Type Adhesive Sheet The “cooling peeling type pressure sensitive adhesive sheet” of the present invention is obtained by, for example, dissolving or dispersing each component of the cooling peeling type pressure sensitive adhesive composition of the present invention in an appropriate solvent to form a solid A method of forming an adhesive layer-forming coating solution having a partial concentration of about 10 to 50% by mass, applying the adhesive layer-forming coating solution so as to cover at least one surface of a substrate, and drying the coating solution according to a conventional method Can be obtained. In addition, when forming the cooling peeling type adhesive composition itself of this invention in a film form or a sheet form and making it into a cooling peeling type adhesive sheet, it may replace with a base material and should just use the film which has mold release property.

  At this time, the adhesive layer-forming coating solution includes various conventionally used additives such as a crosslinking accelerator, an antioxidant, a stabilizer, a viscosity modifier, a tackifier resin, or an organic or inorganic filler. May be added. Examples of the crosslinking accelerator include triethylamine-based, cobalt naphthenate-based, and tin-based crosslinking accelerators, and in particular, stannous chloride, tetra-n-butyltin, trimethyltin hydroxide, dimethyltin chloride, dilaurate. It is preferable to use a tin-based crosslinking accelerator such as -n-butyltin. In addition, as an antioxidant, a phenolic antioxidant, etc., as a tackifier resin, a terpene resin, etc., as an organic filler, an acrylic or urethane spherical fine particle, etc., as an inorganic filler Silica, calcium carbonate, alumina and the like can be preferably used.

  There are no particular restrictions on the method of application, and a conventionally known application using a Mayer bar, applicator, brush, spray, roller, gravure coater, die coater, lip coater, comma coater, knife coater, reverse coater, spin coater, etc. The method can be used. The surface of the substrate to which the adhesive layer-forming coating solution is applied or the film having releasability (hereinafter referred to as “substrate etc.”) may be subjected to surface treatment in advance as necessary. .

  There is no restriction | limiting in particular also about a drying method, Conventionally well-known drying methods, such as hot air drying and reduced pressure drying, can be utilized. About drying conditions, what is necessary is just to set suitably according to the kind of adhesive, the kind of solvent used by coating liquid, the film thickness of an adhesion layer, etc., but it is common to dry at the temperature of about 60-180 ° C. Is.

  In addition, depending on the amount of volatile matter remaining in the adhesive layer (hereinafter referred to as “residual volatile matter amount”), the adhesiveness between the adhesive layer and the substrate or the peelability after cooling may be adversely affected. Accordingly, the residual volatile content in the adhesive layer is preferably 4% by mass or less, and more preferably 2% by mass or less. In addition, what is necessary is just to adjust the quantity of the solvent for preparing the adhesion layer formation coating liquid, the drying time after coating, etc. in order to set it as the desired residual volatile matter amount.

[3] Method for Manufacturing Electronic Component In the method for manufacturing an electronic component of the present invention, a workpiece, which is a precursor of an electronic component, is temporarily fixed to a releasable adhesive sheet, and the temporarily fixed workpiece is processed. This is a method for producing an electronic component comprising a step of removing a releasable pressure-sensitive adhesive sheet to obtain a processed product, and the cooling peelable pressure-sensitive adhesive sheet of the present invention is used as the removable pressure-sensitive adhesive sheet.

  The method for producing an electronic component of the present invention is characterized in that the cooling-peelable pressure-sensitive adhesive sheet of the present invention is used as a removable sheet, and the other points are the same as the conventional method. In the case of producing a multilayer ceramic capacitor, it is usually carried out in the following manner.

  First, a slurry containing ceramic powder, a dispersion medium, a binder, and the like is thinned using a doctor blade method, a calendar method, or the like to obtain a ceramic green sheet. Next, after printing metal electrodes (internal electrodes) on the surface of the ceramic green sheet, a large number of these are laminated, thermocompression bonded, and integrated to form a metal electrode (a precursor of the multilayer ceramic capacitor) between layers ( A ceramic green sheet laminate (hereinafter simply referred to as “laminate”) in which the internal electrodes) are disposed is obtained.

  Further, the laminate is temporarily fixed to the cooling peelable pressure-sensitive adhesive sheet of the present invention, and the workpiece is attached to the temporarily fixed laminate by a cutting device such as a dicer or a guillotine blade at a high temperature of about 80 to 100 ° C. After performing dicing processing to cut into small pieces of ridges and cooling, cool to room temperature region, peel off the cooling peelable pressure-sensitive adhesive sheet of the present invention, and a large number of chips (sometimes called "work") obtain. Finally, the chip is fired, and a metal electrode (external electrode) is printed on the surface thereof, whereby a multilayer ceramic capacitor as a final product can be obtained.

  As described above, the electronic component manufacturing method of the present invention is a ceramic green sheet laminate in which a workpiece is a multilayer ceramic capacitor precursor, a metal electrode is disposed between layers, and the workpiece is processed. It can be suitably used in the case of a dicing process in which the body is cut into small pieces by cutting the body. However, the electronic component manufacturing method of the present invention can be applied not only to the manufacture of multilayer ceramic capacitors, but also to the general manufacturing of electronic components that are processed in a state in which a workpiece is temporarily fixed. Specifically, it can be suitably used for the production of various electronic parts such as multilayer ceramic capacitors, multilayer ceramic inductors, resistors, ferrites, sensor elements, thermistors, varistors, piezoelectric ceramics, and silicon wafers.

  Hereinafter, the cooling peelable pressure-sensitive adhesive composition of the present invention and the cooling peelable pressure sensitive adhesive sheet will be specifically described with reference to examples, but the cooling peelable pressure sensitive adhesive composition of the present invention and the cooling peelable pressure sensitive adhesive sheet are It is not limited at all by these examples. In addition, about the cooling peeling type adhesive composition of an Example and a comparative example, and a cooling peeling type adhesive sheet, it evaluates about four items of initial stage adhesive force, adhesive force at the time of high temperature, peeling force after cooling, and peelability with respect to a green sheet. did. These items were evaluated by the following methods.

[Initial adhesive strength]
After manufacturing, the heat-removable or ultraviolet irradiation treatment-free and peelable adhesive sheets of Examples and Comparative Examples were cut into a width of 25 mm and a length of 250 mm to obtain a test piece. A 25 μm polyester film (trade name: Lumirror T60, manufactured by Toray Industries, Inc.) was pressure-bonded by reciprocating a rubber roller under the conditions of a pressing force of 2 kg and a speed of 300 mm / min. The initial adhesive strength was evaluated by measuring the adhesive strength (peeling strength) when peeled in the 180 ° direction at a tensile speed of 300 mm / min. These steps were all performed under conditions of a temperature of 23 ° C. and a humidity of 65% RH.

[Adhesive strength at high temperature]
In the same way as the initial adhesive strength, a 25 μm thick polyester film was pressure-bonded to the test piece and left for 20 minutes, and further left for 30 minutes in either 80 ° C. or 100 ° C. temperature atmosphere, The adhesive strength at high temperature was evaluated by measuring the adhesive strength (peeling strength) when peeled in a 180 ° direction at a tensile speed of 300 mm / min with a tensile tester. “Adhesion at high temperature” in the table indicates that peeling was not observed at any temperature of 80 ° C. and 100 ° C., and “peeling” was observed at any temperature of 80 ° C. or 100 ° C. Expressed as “x”.

[Peeling force after cooling]
In the same manner as the initial adhesive strength, a 25 μm thick polyester film was pressure-bonded to the test piece and allowed to stand for 20 minutes, and then allowed to stand in a temperature atmosphere of 100 ° C. for 30 minutes. After cooling under the condition of 65% RH and allowing to stand for 30 minutes, by measuring the adhesive force (peeling force) when peeled in a 180 ° direction with a tensile speed of 300 mm / min, after cooling, The peel force was evaluated.

[Peelability for green sheets]
100 parts by mass of a methyl methacrylate copolymer (trade name: Paraloid B-82, manufactured by Rohm and Haas Japan Co., Ltd.), 2 parts by mass of diethyl phthalate, 430 parts by mass of barium titanate (average particle size 0.5 μm), And 160 mass parts of toluene was stirred and mixed, and the coating liquid for green sheet preparation was prepared. Next, the above coating is applied so that the dry film thickness is about 50 μm on the silicone-treated surface of the release polyester film (trade name: MRX 50 μm, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) coated with a silicone resin on one side. The solution was applied, dried at 80 ° C. for 5 minutes, and then peeled off from the peeling polyester film to prepare a ceramic green sheet.

Twenty ceramic green sheets were laminated and pressed at a pressing force of 300 kg / cm ² to obtain a green sheet laminated body, which was cut into a size of 10 mm × 5 mm to produce a chip. An evaluation sample was prepared by pressure-bonding this chip to the cooling and peeling type pressure-sensitive adhesive sheets of Examples and Comparative Examples. This evaluation sample was heated at 100 ° C. for 5 minutes, cooled under conditions of a temperature of 23 ° C. and a humidity of 65% RH, and then peeled from the pressure-sensitive adhesive sheet to evaluate the peelability after cooling. Specifically, “○” indicates that the adhesive sheet can be easily peeled off without breakage or deformation of the chip, “No” indicates that the peelable sheet cannot be peeled, and if the chip is damaged or deformed even if it is peelable. “×” was evaluated.

  In the examples and comparative examples, the following polymers and crosslinking agents were used.

(A-1 component)
It is an acrylic resin having a weight average molecular weight of 700,000 and a glass transition temperature of 15 ° C. Constituent monomers include ethyl acrylate, methyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, and acrylonitrile, and the constituent mass ratio thereof is 43.7: 25: 20: 1.3: 10). That is, it is a polymer containing 98.7% by mass of an acrylic acid or methacrylic acid ester monomer ester-bonded with an alkyl group having 1 to 4 carbon atoms and 1.3% by mass of a monomer having a hydroxyl group.

(A-2 component)
It is an acrylic resin having a weight average molecular weight of 360,000 and a glass transition temperature of 20 ° C. Constituent monomers include butyl methacrylate and 2-hydroxyethyl methacrylate, and the constituent mass ratio is 98.7: 1.3. That is, all of the constituent monomers are acrylic acid or methacrylic acid ester monomers in which an alkyl group having 1 to 4 carbon atoms is ester-bonded, and are polymers containing 1.3% by mass of a monomer having a hydroxyl group.

(B-1 component)
It is an acrylic resin having a weight average molecular weight of 390,000 and a glass transition temperature of −42 ° C. Constituent monomers include 2-ethylhexyl acrylate, 2-hydroxyethyl methacrylate, and vinyl acetate, and the constituent mass ratio is 63.7: 1.3: 35. That is, it is a polymer containing 63.7% by mass of an acrylic acid or methacrylic acid ester monomer having an ester bond with an alkyl group having 6 to 8 carbon atoms and 1.3% by mass of a monomer having a hydroxyl group.

(B-2 component)
It is an acrylic resin having a weight average molecular weight of 400,000 and a glass transition temperature of −68 ° C. Constituent monomers include 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate, and the constituent mass ratio is 97.4: 2.6. That is, all of the constituent monomers are acrylic acid or methacrylic acid ester monomers in which an alkyl group having 6 to 8 carbon atoms is ester-bonded, and are polymers containing 3.9% by mass of a monomer having a hydroxyl group.

(B-3 component)
It is an acrylic resin having a weight average molecular weight of 800,000 and a glass transition temperature of −67 ° C. Constituent monomers include 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate, and the constituent mass ratio is 96.1: 3.9. That is, all of the constituent monomers are acrylic acid or methacrylic acid ester monomers in which an alkyl group having 6 to 8 carbon atoms is ester-bonded, and are polymers containing 3.9% by mass of a monomer having a hydroxyl group.

(B-4 component)
It is an acrylic resin having a weight average molecular weight of 400,000 and a glass transition temperature of −54 ° C. Constituent monomers include 2-hydroxyethyl methacrylate and butyl acrylate, and the constituent mass ratio is 1.3: 98.7. That is, it is a polymer containing 1.3% by mass of an acrylic acid or methacrylic acid ester monomer having an ester bond with an alkyl group having 6 to 8 carbon atoms and 3.9% by mass of a monomer having a hydroxyl group.

(Crosslinking agent)
It is an isocyanate-based crosslinking agent, and its constituent component is a trimer of hexamethylene diisocyanate (trade name: Takenate D-170N, manufactured by Mitsui Takeda Chemical Co., Ltd.).

(Examples 1-4)
As the temperature-sensitive adhesive polymer, the A-1 component shown in Table 1 is used, and as the low-polar adhesive polymer, the B-1 or B-2 component shown in Table 1 is used. To 100 parts by mass of the mixture at a mass ratio of 0.6, 0.6 parts by mass of the crosslinking agent and 300 parts by mass of a mixed solvent in which methyl ethyl ketone and toluene are mixed at a mass ratio of 1: 1 are added and stirred and mixed. An adhesive layer forming coating solution was prepared.

  Next, this adhesive layer forming coating solution was applied to the surface of a polyester film having a thickness of 100 μm as a base material according to a conventional method so that the film thickness after drying was 25 μm, and this was applied at 80 ° C. for 1 minute. Further, an adhesive layer was formed by drying at 130 ° C. for 3 minutes. A 30 μm-thick stretched polypropylene (OPP: Oriented Polypropylene, product name: Alphan, Oji Paper Co., Ltd.) film was attached to the surface of the adhesive layer as a release liner, and the temperature was maintained at 23 ° C. for 1 week. By curing, a peelable pressure-sensitive adhesive sheet was obtained. Table 1 shows the results of evaluating the initial pressure-sensitive adhesive strength, the high-temperature pressure-sensitive adhesive strength, the post-cooling pressure-sensitive adhesive strength, and the peelability with respect to the green sheet.

(Comparative Examples 1-2)
Using each component shown in Table 1 and mixing them at a mass ratio shown in Table 1, 100 parts by mass of the crosslinking agent is 0.6 parts by mass, and methyl ethyl ketone and toluene are in a mass ratio of 1: 1. 300 parts by mass of the mixed solvent mixed in (1) was added and stirred and mixed to prepare an adhesive layer forming coating solution. About the subsequent process, it carried out similarly to Examples 1-4, and obtained the cooling peeling type adhesive sheet. Table 1 shows the results of evaluating the initial pressure-sensitive adhesive strength, the high-temperature pressure-sensitive adhesive strength, the post-cooling pressure-sensitive adhesive strength, and the peelability with respect to the green sheet.

(Evaluation)
As shown in Table 1, all of the cooling peelable adhesive sheets of Examples 1 to 4 have an initial adhesive strength of 0.05 N / 25 mm or less, a high temperature adhesive strength of 1 N / 25 mm or more, and a post-cooling adhesive strength of 0.05 N. / 25 mm or less. That is, since the adhesive force at high temperature is sufficiently high, it can be expected that the adherend can be reliably fixed even in a high temperature region of 80 to 100 ° C. Moreover, the adhesive force after cooling is reliably reduced to 0.05 N / 25 mm or less. In the evaluation of the peelability for the green sheet, the green sheet could be easily peeled without being damaged or deformed, and a good result was shown.

  On the other hand, the cooling peelable adhesive sheets of Comparative Examples 1 and 2 have an initial adhesive strength of 0.05 N / 25 mm or less and a high temperature adhesive strength of 1 N / 25 mm or more, but the measurement of the high temperature adhesive strength at 100 ° C. In this case, a transfer phenomenon occurs in which the pressure-sensitive adhesive layer peels off from the base material of the pressure-sensitive adhesive sheet and transfers to the adherend, making it impossible to measure the adhesive strength at high temperatures. This makes it difficult to securely fix the adherend in a high temperature region. In Comparative Example 1, the peel force after cooling exceeded 0.05 N / 25 mm, and it was found that the comparative example 1 was not suitable for processing of the green sheet.

(Examples 5-6)
As the temperature-sensitive adhesive polymer, the component A-1 shown in Table 2 is used, and as the low-polar adhesive polymer, the component B-4 shown in Table 2 is used, or the low-polar adhesive polymer is completely used. Without using a mixed solvent in which these were mixed at a mass ratio shown in Table 2 with respect to 100 parts by mass, the crosslinking agent was mixed with 0.6 parts by mass, and methyl ethyl ketone and toluene were mixed at a mass ratio of 1: 1. 300 parts by mass was added and stirred and mixed to prepare an adhesive layer-forming coating solution. About other parts, it carried out similarly to Example 1, and obtained the cooling peeling type adhesive sheet. Table 2 shows the results of evaluating the initial pressure-sensitive adhesive strength, the high-temperature pressure-sensitive adhesive strength, and the post-cooling peeling strength of the cooled peelable PSA sheet.

  Moreover, the peelability with respect to a polyimide film was evaluated by the following methods. After the production, the cooling release adhesive sheet of Examples 5 and 6 that was not subjected to heat treatment or ultraviolet irradiation treatment was cut into a width of 25 mm and a length of 250 mm to obtain a test piece. A 25 μm polyimide film (trade name: Kapton 100H, manufactured by Toray DuPont Co., Ltd.) is pressure-bonded by reciprocating a rubber roller under the conditions of a pressing force of 2 kg and a speed of 300 mm / min. It was. This evaluation sample was heated at 100 ° C. for 30 minutes, cooled under conditions of a temperature of 23 ° C. and a humidity of 65% RH, and then peeled off from the pressure-sensitive adhesive sheet to evaluate the peelability after cooling.

  As shown in Table 2, the adhesive sheets of Examples 5 and 6 have an initial peel strength of 0.2 N / 25 mm or less, a high temperature adhesive strength of 1 N / 25 mm or more, and a cooling adhesive strength of 0.2 N / 25 mm or less. there were. That is, since the adhesive force at high temperature is sufficiently high, it can be expected that the adherend can be reliably fixed even in a high temperature region of 80 to 100 ° C. Moreover, the adhesive force after cooling is reliably reduced to 0.2 N / 25 mm or less. Furthermore, in the evaluation of the peelability for the polyimide film, any of the pressure-sensitive adhesive sheets of Examples 5 and 6 can be easily peeled without generating wrinkles or curls on the polyimide film, and shows a good result. .

  The cooling peelable pressure-sensitive adhesive composition of the present invention, and the cooling peelable pressure-sensitive adhesive sheet securely fix the adherend in a high temperature region, and when it is desired to peel from the adherend, it can be reliably peeled, It can be used suitably for the production of various printed circuit boards and TAB, and for the production of various electronic components such as multilayer ceramic capacitors, multilayer ceramic inductors, resistors, ferrites, sensor elements, thermistors, varistors, piezoelectric ceramics, and silicon wafers. it can.

Claims (9)

  Adhesive polymer is included as an active ingredient, and the initial adhesive strength in a temperature range of 0 to 30 ° C. (normal temperature range) is 0.2 N / 25 mm or less, and adhesion in a temperature range of 80 to 100 ° C. (high temperature range) Cooling peelable pressure-sensitive adhesive composition having a strength (adhesive strength at high temperature) of 1 N / 25 mm or more and an adhesive strength after cooling from the high temperature region to the normal temperature region (adhesive strength after cooling) of 0.2 N / 25 mm or less Stuff.   The main constituent monomer is an acrylic acid or methacrylic acid ester monomer in which an alkyl group having 1 to 4 carbon atoms is ester-bonded, and consists of an acrylic resin having a weight average molecular weight (Mw) of 600,000 or more, and its glass transition A cooling peelable pressure-sensitive adhesive composition comprising a temperature-sensitive adhesive polymer having a temperature (Tg) in a temperature range of -10 to 30 ° C.   The temperature-sensitive adhesive polymer and at least a part of the constituent monomer is made of an acrylic resin which is an acrylic acid or methacrylic acid ester monomer in which an alkyl group having 6 to 8 carbon atoms is ester-bonded. Is an adhesive polymer composed of a low-polar adhesive polymer that is lower than the temperature-sensitive adhesive polymer and a crosslinking agent capable of crosslinking between these polymers as an active ingredient, The cooling peelable pressure-sensitive adhesive composition according to claim 2, comprising a crosslinked polymer derived from an active ingredient.   An acrylic polymer having a weight average molecular weight (Mw) of 600,000 or more, wherein the adhesive polymer is an acrylic acid or methacrylic acid ester monomer in which an alkyl group having 1 to 4 carbon atoms is ester-bonded. The cooling peelable pressure-sensitive adhesive composition according to claim 1, comprising a temperature-sensitive adhesive polymer made of a resin and having a glass transition temperature (Tg) in a temperature range of -10 to 30 ° C.   The adhesive polymer comprises an acrylic resin in which at least a part of the constituent monomer is an acrylic acid or methacrylic acid ester monomer having an alkyl group having 6 to 8 carbon atoms ester-bonded, and the polarity of the alkyl group is The cooling peelable pressure-sensitive adhesive composition according to claim 4, further comprising a low-polarity adhesive polymer that is lower than the warm adhesive polymer.   A cooling peelable pressure-sensitive adhesive sheet comprising a film-like or sheet-like base material, and having a pressure-sensitive adhesive layer containing the cooling peelable pressure-sensitive adhesive composition according to any one of claims 1 to 5 on at least one surface thereof. .   The pressure-sensitive adhesive layer is formed with a concentration gradient that distributes the low-polarity pressure-sensitive adhesive polymer or the cross-linked polymer that is cross-linked by the cross-linking agent so that the surface of the pressure-sensitive adhesive layer has a higher concentration than the substrate side. The cooling peelable pressure-sensitive adhesive sheet according to claim 6, which is a product. A workpiece to be processed, which is a precursor of an electronic component, is temporarily fixed to a releasable pressure-sensitive adhesive sheet. After the temporarily fixed workpiece is processed, the re-peelable pressure-sensitive adhesive sheet is peeled off to obtain a processed body. A method of manufacturing an electronic component comprising a step of obtaining
The manufacturing method of the electronic component which uses the cooling peelable adhesive sheet of Claim 6 or 7 as said re-peelable adhesive sheet. The workpiece is a ceramic green sheet laminate in which metal electrodes are disposed between layers, which is a precursor of a multilayer ceramic capacitor,
The method of manufacturing an electronic component according to claim 8, wherein the processing is a dicing process in which the workpiece is cut into small pieces by cutting the workpiece.