KR20170129604A - Temperature sensitive adhesive - Google Patents

Abstract

The purpose of the present invention is to provide a temperature-sensitive adhesive which can temporarily fix a workpiece in a stable state and peels simply the workpiece. The temperature-sensitive adhesive contains a branched chain crystalline polymer, which is crystalized at the temperature below a melting point and shows flexibility at the temperature of the melting point or more. A storage modulus (G) of the temperature-sensitive adhesive is 1x10^6 Pa at 23C or more and below 45C, and 1x10^4 to 5x10^4 Pa at 60C or more. The branched chain crystalline polymer is a copolymer of (meth)acrylate, having a linear alkyl group having at least 22 carbon atoms, and (meth)acrylate having alkyl group having 2 to 8 carbon atoms. It is preferable that the (meth)acrylate having a linear alkyl group having at least 22 carbon atoms is contained by the rate of 50 wt% or more among monomer components.

Description

{TEMPERATURE SENSITIVE ADHESIVE}

The present invention relates to a thermosensitive adhesive which can be used as a temporary fixing material.

However, the conventional toughness is easily deteriorated by the heat generated during dicing, and the cutting accuracy is poor because the workpiece is displaced or depressed at the time of cutting. In order to solve such a problem, it is required that the workpiece be fixed to the workpiece in a stable state.

Further, it is also required that the workpiece can be easily peeled off from the workpiece. For example, a wax is known as a waxy material (see, for example, Patent Document 1).

However, since the fixing force is hardly lowered in the wax, if the workpiece is fixed with the wax, it is difficult to peel off the workpiece, and furthermore, the wax remains in the peeled workpiece.

Japanese Unexamined Patent Application Publication No. 6-69324

A problem to be solved by the present invention is to provide a thermosensitive pressure-sensitive adhesive capable of temporarily fixing a workpiece in a stable state and easily separating the workpiece.

The thermosensitive pressure-sensitive adhesive of the present invention contains a side chain crystalline polymer which crystallizes at a temperature lower than the melting point and exhibits fluidity at a temperature higher than the melting point, and has a storage elastic modulus (G ') at 23 ° C or more and 45 ° C or less, ⁶ Pa or more and a storage elastic modulus (G ') at 60 deg. C or higher is 1 x 10 ^{4 to} 5 x 10 ⁴ Pa.

According to the present invention, the workpiece can be fixed in a stable state, and the workpiece can be easily peeled off.

Fig. 1 is a graph showing the measurement results of the storage elastic modulus (G ') in the examples. Fig.

≪ Temperature Sensitive Adhesive >

Hereinafter, the thermosensitive adhesive according to one embodiment of the present invention will be described in detail.

The thermosensitive adhesive of the present embodiment contains a side chain crystalline polymer. The side chain crystalline polymer is a polymer having a melting point. The melting point is a temperature at which a specific part of a polymer which has been initially adjusted to an ordered arrangement by a certain equilibrium process becomes a disordered state and a value obtained by measurement under a measuring condition of 10 ° C / minute by a differential scanning calorimeter (DSC) .

The side chain crystalline polymer crystallizes at a temperature lower than the above-mentioned melting point, and exhibits fluidity at the temperature above the melting point. That is, the side chain crystalline polymer has a thermosensitive property that reversibly causes a crystalline state and a flow state in response to a temperature change. By this, when the side chain crystalline polymer is caused to flow at a temperature higher than the melting point by the temperature of the pressure sensitive adhesive, the pressure sensitive adhesive follows the fine uneven shape present on the surface of the adherend. When the thermosensitive adhesive in this state is cooled to a temperature lower than the melting point, the side chain crystalline polymer is crystallized to form so-called anchor effect, and as a result, the adherend can be fixed with high fixing force. In addition, when the thermosensitive adhesive is heated to a temperature higher than the melting point, the side chain crystalline polymer exhibits fluidity so that the cohesive force of the thermosensitive adhesive is lowered, so that the fixing force described above can be sufficiently lowered and the adherend can be released from the thermosensitive adhesive . Therefore, the thermosensitive pressure-sensitive adhesive of the present embodiment can be temporarily fixed on the workpiece by the same method of use as the wax.

When the temperature sensitive adhesive of the present embodiment is heated to a temperature higher than the melting point and then to a temperature lower than the melting point, in other words, when the side chain crystalline polymer is changed from the fluidized state to the crystalline state, And contains a crystalline polymer. That is, the thermosensitive adhesive of the present embodiment contains a side chain crystalline polymer as a main component.

Sensitive adhesive of the present embodiment has a storage elastic modulus (G ') of not less than 1 x 10 ⁶ Pa, preferably 1 x 10 ^{6 to} 1 x 10 ⁸ Pa at a temperature of not less than 23 ° C and less than 45 ° C, The storage modulus (G ') at 60 to 100 ° C is preferably 1 × 10 ^{4 to} 5 × 10 ⁴ Pa. According to this configuration, the workpiece can be fixed in a stable state, and the workpiece can be easily peeled off. More specifically, for example, when the thermosensitive adhesive of the present embodiment is used as a temporary fixture in the production process of a multilayer ceramic capacitor, the temperature sensitive adhesive is about 40 ° C due to heat generation at the time of dicing. Since the temperature sensitive adhesive of the present embodiment has a storage elastic modulus (G ') of 23 占 폚 or more and less than 45 占 폚 of 1 占¹⁰⁶ Pa or more, a high elastic modulus can be maintained against heat generation during processing, It is possible to suppress the retention of the thermosensitive adhesive. As a result, it is possible to suppress the occurrence of shifts and depressions of the workpiece at the time of cutting, and cut precision can be improved. Since the temperature sensitive adhesive of the present embodiment has a storage modulus (G ') at 60 ° C or higher of 1 x 10 ^{4 to} 5 x 10 ⁴ Pa, when the temperature sensitive adhesive is heated at 60 ° C or higher, the cohesive force of the thermosensitive adhesive So that the work can be simply peeled off. In addition, it is also possible to suppress the occurrence of so-called residual pressure-sensitive adhesive, in which a thermosensitive pressure-sensitive adhesive remains in the peeled workpiece.

The storage elastic modulus (G ') is a value obtained by measuring by a measuring method described in the following embodiments. The storage elastic modulus (G ') can be adjusted by, for example, changing the composition of the side chain crystalline polymer.

The side chain crystalline polymer is preferably at least a copolymer of (meth) acrylate having a linear alkyl group having at least 22 carbon atoms and (meth) acrylate having an alkyl group having from 2 to 8 carbon atoms. (Meth) acrylate means acrylate or methacrylate.

(Meth) acrylate having a straight chain alkyl group having 22 or more carbon atoms functions as a side chain crystalline site in the side chain crystalline polymer in which the straight chain alkyl group having 22 or more carbon atoms is contained. That is, the side chain crystalline polymer is a comb-like polymer having a linear alkyl group having at least 22 carbon atoms in its side chain, and the side chains are aligned in an ordered arrangement due to the intermolecular force or the like to crystallize.

Examples of the (meth) acrylate having a straight chain alkyl group having 22 or more carbon atoms include behenyl (meth) acrylate and the like. The (meth) acrylate having a straight chain alkyl group having at least 22 carbon atoms may be used alone or in combination of two or more. The upper limit of the number of carbon atoms is preferably 50, but is not limited thereto. (Meth) acrylate having a linear alkyl group having at least 22 carbon atoms is contained in the monomer component in a proportion of preferably 50% by weight or more, and more preferably 50 to 75% by weight. The (meth) acrylate having a linear alkyl group having 22 or more carbon atoms is preferably contained in a larger proportion than the (meth) acrylate having an alkyl group having 2 to 8 carbon atoms in the monomer component.

(Meth) acrylate having an alkyl group having 2 to 8 carbon atoms functions as a coagulation component in the side chain crystalline polymer. (Meth) acrylate having a relatively long alkyl group of 2 to 8 carbon atoms as a monomer component, the releasability at high temperature tends to be improved.

Examples of the (meth) acrylate having an alkyl group having 2 to 8 carbon atoms include ethyl (meth) acrylate, butyl (meth) acrylate, and hexyl (meth) acrylate. The exemplified (meth) acrylates may be used alone or in combination of two or more. (Meth) acrylate having an alkyl group having 2 to 8 carbon atoms is contained in the monomer component in an amount of preferably 50% by weight or less, more preferably 20 to 45% by weight.

The monomer component may contain other monomers copolymerizable with the above-mentioned (meth) acrylate. Examples of other monomers include polar monomers and the like.

Examples of the polar monomer include ethylenic unsaturated monomers having a carboxyl group such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, and fumaric acid; And ethylenically unsaturated monomers having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and 2-hydroxyhexyl (meth) acrylate. The polar monomers mentioned may be used alone or in combination of two or more. The polar monomer is preferably contained in the monomer component in a proportion of 10% by weight or less, more preferably 1 to 10% by weight.

Preferable composition of the side chain crystalline polymer is 50 to 75% by weight of behenyl acrylate, 20 to 45% by weight of butyl acrylate and 5% by weight of 2-hydroxyethyl acrylate.

Examples of the polymerization method of the monomer component include a solution polymerization method, a bulk polymerization method, a suspension polymerization method and an emulsion polymerization method. When a solution polymerization method is employed, the monomer component and the solvent are mixed, and if necessary, a polymerization initiator, a chain transfer agent or the like is added and the mixture is reacted at about 40 to 90 캜 for about 2 to 10 hours while stirring.

The weight average molecular weight of the side chain crystalline polymer is preferably 100000 or more, more preferably 300000 to 900000, and still more preferably 400000 to 700000. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) and a value obtained by converting the measured value into polystyrene.

The melting point of the side chain crystalline polymer is preferably 45 ° C or more and less than 60 ° C. The melting point can be adjusted by changing the composition of the monomer component or the like.

The thermosensitive adhesive of the present embodiment may further contain a crosslinking agent. Examples of the crosslinking agent include metal chelate compounds, aziridine compounds, isocyanate compounds, and epoxy compounds.

The crosslinking agent is contained in an amount of preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the side chain crystalline polymer.

The crosslinking reaction can be carried out by adding a crosslinking agent to the thermosensitive adhesive, followed by heating. The heating conditions include a temperature of about 90 to 110 DEG C and a time of about 1 minute to about 20 minutes.

The above-described pressure-sensitive adhesive of the present embodiment can be used, for example, as a temporary fixture for the production of ceramic parts. Examples of ceramic parts include multilayer ceramic capacitors, ceramic inductors, and ceramic varistors.

The mode of use of the thermosensitive adhesive is not particularly limited and may be used as it is or may be used in the form of an adhesive sheet or an adhesive tape as described below.

<Temperature Sensitive Adhesive Sheet>

The thermosensitive adhesive sheet of the present embodiment includes the above-mentioned thermosensitive adhesive, and is a sheet-like sheet without a substrate. The thickness of the thermosensitive adhesive sheet is preferably 10 to 400 mu m.

A releasing film may be laminated on the surface of the thermosensitive adhesive sheet. Examples of the release film include those coated with a releasing agent such as silicone on the surface of a film made of polyethylene terephthalate or the like. The thickness of the release film is preferably 5 to 500 mu m, more preferably 25 to 250 mu m. The releasing film is peeled off when the heat sensitive adhesive sheet is used.

<Temperature Sensitive Adhesive Tape>

The thermosensitive adhesive tape of the present embodiment includes a base material film and a pressure-sensitive adhesive layer laminated on at least one side of the base material. The film phase is not limited to a film but is a concept including a film phase or a sheet phase as long as the effect of the present embodiment is not impaired.

Examples of the constituent material of the substrate include polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, poly And synthetic resins such as vinyl chloride.

The structure of the substrate may be either a single-layer structure or a multi-layer structure. The thickness of the substrate is preferably 5 to 500 mu m, more preferably 25 to 250 mu m. The substrate may be subjected to surface treatment in order to improve the adhesion to the pressure-sensitive adhesive layer. Examples of the surface treatment include a corona discharge treatment, a plasma treatment, a blast treatment, a chemical etching treatment, a primer treatment, and the like.

The pressure-sensitive adhesive layer laminated on at least one side of the base material includes the above-mentioned pressure-sensitive adhesive. In order to laminate the pressure-sensitive adhesive layer on at least one side of the substrate, for example, a solvent is added to the thermosensitive pressure-sensitive adhesive to prepare a coating liquid, and the resulting coating liquid is coated on one side or both sides of the substrate with a coater or the like and dried. Examples of the coater include a knife coater, a roll coater, a calender coater, a comma coater, a gravure coater, a road coater, and the like.

The thickness of the pressure-sensitive adhesive layer is preferably 5 to 60 占 퐉, more preferably 10 to 60 占 퐉, and still more preferably 10 to 50 占 퐉.

When the pressure-sensitive adhesive layer is laminated on both sides of the substrate, the thickness of the pressure-sensitive adhesive layer on one side and the pressure-sensitive adhesive layer on the other side may be the same or different from each other. The pressure sensitive adhesive layer on the other side is not particularly limited as long as the pressure sensitive adhesive layer on one side is composed of the above-mentioned pressure sensitive adhesive. The pressure-sensitive adhesive layer on the other surface may be constituted by, for example, a pressure-sensitive adhesive. Examples of the pressure-sensitive adhesive include natural rubber adhesives, synthetic rubber adhesives, styrene-butadiene latex base adhesives, acrylic adhesives, and the like.

A release film may be laminated on the surface of the thermosensitive adhesive tape. As the release film, those exemplified in the above-mentioned pressure sensitive adhesive sheet are listed. The releasing film is peeled off when the heat sensitive adhesive tape is used.

&Lt; Manufacturing Method of Ceramic Parts > - Manufacturing Method of Multilayer Ceramic Capacitor &

Next, a method of manufacturing a ceramic part and a method of manufacturing a multilayer ceramic capacitor according to an embodiment of the present invention will be described. The manufacturing method of the ceramic part of the present embodiment uses the above-described thermosensitive adhesive tape and includes the following steps (i) to (iv). The method for manufacturing the multilayer ceramic capacitor of the present embodiment further includes the following step (v).

(i) A thermosensitive adhesive tape is interposed between the ceramic green sheet laminate and the pedestal in a state in which the pressure sensitive adhesive layer faces the ceramic green sheet laminate.

(ii) The temperature of the thermosensitive adhesive tape is set to a temperature equal to or higher than the melting point and then the temperature is lower than the melting point, and the ceramic green sheet laminate is temporarily fixed on the pedestal through the thermosensitive adhesive tape.

(iii) The ceramic green sheet laminate is cut to form a plurality of green chips.

(iv) The temperature of the thermosensitive adhesive tape is set at a temperature higher than the melting point, and a plurality of chips are peeled from the thermosensitive adhesive tape.

(v) The obtained green chip is fired to obtain a ceramic chip, and an external electrode is formed on the end face of the ceramic chip to obtain a multilayer ceramic capacitor.

Among the steps (i) to (v) described above, the step (iii) is so-called dicing. According to this embodiment, a sufficient fixing force can be maintained from the room temperature (23 DEG C) to the temperature (about 40 DEG C) of the dicing process in the step (iii) from the viewpoint of using the above-mentioned thermosensitive adhesive tape. In the step (iii), even if the temperature sensitive adhesive is heated to about 40 占 폚 due to the heat generated during the dicing process, the pressure sensitive adhesive layer can be prevented from being sagged and the ceramic green sheet laminate can be cut with excellent cutting precision . In the step (iv), when the temperature of the thermosensitive adhesive tape is set to a temperature higher than the melting point, the fixing force of the thermosensitive adhesive tape is sufficiently lowered, so that the plural chips can be smoothly peeled off from the thermosensitive adhesive tape, Parts and multilayer ceramic capacitors can be obtained. (iv) is preferably carried out at 60 to 80 캜.

In the ceramic green sheet laminate in the step (i), a slurry of the ceramic powder is thinly extended by a doctor blade to form a ceramic green sheet, a plurality of electrodes are printed on the surface of the ceramic green sheet, Of ceramic green sheets laminated together.

Examples of the method of fixing the thermosensitive adhesive tape to the pedestal in the step (ii) include a method of fixing the thermosensitive adhesive tape to the pedestal with a predetermined adhesive or adhesive interposed between the substrate of the thermosensitive adhesive tape and the pedestal, A method of employing a pedestal having a fixing means, and the like. In the case of a double-sided tape having a pressure sensitive adhesive tape laminated on both sides of a substrate, the pressure sensitive adhesive tape may be fixed to the pedestal through a pressure sensitive adhesive layer on the opposite side to the pressure sensitive adhesive layer on one side to which the ceramic green sheet laminate is fixed have.

The cutting in the step (iii) is not particularly limited as long as the ceramic green sheet laminate can be cut into a plurality of green chips. The cutting may be performed by a cutting blade or by a rotary blade.

The method of manufacturing the ceramic part of the present embodiment can be applied to other ceramic parts such as ceramic inductor and ceramic varistor as well as the above-described multilayer ceramic capacitor.

Hereinafter, the present invention will be described in detail with reference to Synthesis Examples and Examples, but the present invention is not limited to the following Synthesis Examples and Examples.

(Synthesis Examples 1 to 4 and Comparative Synthesis Examples: side chain crystalline polymer)

First, the monomer shown in Table 1 was added to the reaction vessel in the ratio shown in Table 1 to obtain a monomer mixture. The monomers shown in Table 1 are as follows.

C22A: Behenyl acrylate

C4A: butyl acrylate

HEA: 2-hydroxyethyl acrylate

Next, 0.5 parts by weight of "perbutyl ND" manufactured by NOF CORPORATION as a polymerization initiator was added to 100 parts by weight of the monomer mixture, and 230 parts by weight of ethyl acetate was added to 100 parts by weight of the monomer mixture to prepare a reaction mixture. .

Then, the obtained mixed solution was stirred at 55 占 폚 for 4 hours to copolymerize the respective monomers to obtain a side chain crystalline polymer. Table 1 shows the weight average molecular weight and melting point of the obtained side chain crystalline polymer. The weight average molecular weight is a value obtained by converting the measured value obtained by GPC measurement into polystyrene. The melting point is a value measured at 10 ° C / min under the measurement conditions using DSC.

Monomer Component ^{1 )}
(weight%)
Weight average molecular weight
Melting point (캜)
C22A C4A HEA Synthesis Example 1 50 45 5 650000 46 Synthesis Example 2 55 40 5 650000 49 Synthesis Example 3 60 35 5 600000 52 Synthesis Example 4 70 25 5 500000 55 Comparative Synthetic Example 45 50 5 600000 43

1) C22A: behenyl acrylate, C4A: butyl acrylate, HEA: 2-hydroxyethyl acrylate

[Examples 1 to 4 and Comparative Example]

&Lt; Production of pressure sensitive adhesive tape >

Sensitive adhesive tapes according to Examples 1 to 4 and Comparative Examples were produced using each of the side chain crystalline polymers obtained in Synthesis Examples 1 to 4 and Comparative Synthesis Examples. The relationships between the side chain crystalline polymers obtained in Synthesis Examples 1 to 4 and Comparative Synthesis Examples, and Examples 1 to 4 and Comparative Examples are as follows.

Example 1: Synthesis Example 1 (C22A: 50% by weight)

Example 2: Synthesis Example 2 (C22A: 55% by weight)

Example 3: Synthesis Example 3 (C22A: 60% by weight)

Example 4: Synthesis Example 4 (C22A: 70% by weight)

Comparative Example: Comparative Synthesis Example (C22A: 45% by weight)

The thermosensitive adhesive tape was produced as follows. First, 100 parts by weight of the respective side chain crystalline polymers obtained in Synthesis Examples 1 to 4 and Comparative Synthesis Example were mixed at a ratio of 2.5 parts by weight to obtain a thermosensitive pressure-sensitive adhesive. The crosslinking agent is Nippon Polyurethane Industry Co., Ltd. The isocyanate compound &quot; Coronate L-45E &quot;

Next, the thermosensitive adhesive obtained was adjusted with ethyl acetate to a solid concentration of 30% by weight to obtain a coating liquid. The obtained coating liquid was applied to one side of a film-like substrate made of polyethylene terephthalate having a thickness of 100 mu m. A crosslinking reaction was then carried out under the conditions of 100 占 폚 for 10 minutes to obtain a thermally sensitive adhesive tape having a pressure-sensitive adhesive layer having a thickness of 40 占 퐉 laminated on one side of the substrate.

<Evaluation>

The storage elastic modulus (G ') was measured for each of the thermally sensitive adhesive tapes obtained in Examples 1 to 4 and Comparative Examples. The measurement method is shown below, and the results are shown in Fig.

(Storage elastic modulus (G '))

HAAKE MARS III, a dynamic viscoelasticity measuring device manufactured by Thermo Scientific, was used and the temperature was measured at a temperature rising rate of 1 Hz, 5 DEG C / minute and 0 to 200 DEG C. [

As apparent from Fig. 1, in all of Examples 1 to 4, the storage elastic modulus (G ') at 23 ° C or more and less than 45 ° C was 1 x 10 ⁶ Pa or more, and the storage elastic modulus (G ') Was 1 × 10 ^{4 to} 5 × 10 ⁴ Pa. When the thermosensitive adhesive tape according to Examples 1 to 4 is used as a temporary fixture, it is expected that the workpiece can be fixed in a stable state, and the workpiece can be easily peeled off.

Claims (10)

(G ') at 23 ° C or more and 45 ° C or less is 1 x 10 ⁶ Pa or more, and further contains a side chain crystalline polymer which crystallizes at a temperature lower than the melting point and exhibits fluidity at a temperature above the melting point, And a storage elastic modulus (G ') at 60 DEG C or higher is 1 x 10 ^{4 to} 5 x 10 ⁴ Pa. The method according to claim 1,
The side chain crystalline polymer is a copolymer of (meth) acrylate having at least a linear alkyl group having at least 22 carbon atoms and (meth) acrylate having an alkyl group having from 2 to 8 carbon atoms,
Wherein said (meth) acrylate having a linear alkyl group having 22 or more carbon atoms is contained in a monomer component in a proportion of 50 wt% or more. The method according to claim 1,
Wherein the (meth) acrylate having a linear alkyl group having 22 or more carbon atoms is contained in the monomer component in a larger proportion than the (meth) acrylate having the alkyl group having 2 to 8 carbon atoms. The method according to claim 1,
Wherein the melting point is 45 占 폚 or higher but lower than 60 占 폚. The method according to claim 1,
Thermosensitive adhesive for manufacturing ceramic parts. 6. The method of claim 5,
Wherein the ceramic component is a multilayer ceramic capacitor. Sensitive adhesive sheet comprising the thermosensitive adhesive according to claim 1. A film substrate,
Sensitive adhesive tape comprising a pressure-sensitive adhesive layer laminated on at least one side of the substrate and comprising the thermosensitive adhesive according to claim 1. A method for manufacturing a ceramic green sheet laminate, comprising the steps of: interposing a thermally sensitive adhesive tape according to claim 8 on a ceramic green sheet laminate with the pressure sensitive adhesive layer facing the ceramic green sheet laminate and the pedestal;
A step of setting the temperature of the thermosensitive adhesive tape to a temperature equal to or higher than the melting point and then lowering the temperature to a temperature lower than the melting point and temporarily fixing the ceramic green sheet laminate to the pedestal through the thermosensitive adhesive tape,
A step of cutting the ceramic green sheet laminate to form a plurality of green chips,
And a step of setting the temperature of the thermosensitive adhesive tape to a temperature equal to or higher than the melting point and peeling the plurality of raw chips from the thermosensitive adhesive tape. A method for producing a multilayer ceramic capacitor, wherein a green chip obtained by the method for manufacturing a ceramic part according to claim 9 is fired to obtain a ceramic chip, and an external electrode is formed on an end face of the ceramic chip to obtain a multilayer ceramic capacitor.

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