KR102195502B1 - Temporary fixing double-sided adhesive tape and temporary fixing method for workpiece using same - Google Patents

Abstract

The double-sided adhesive tape for temporary fixation of the present invention includes a substrate, a first adhesive layer attached to a base, and a second adhesive layer attached to a workpiece. The first pressure-sensitive adhesive layer contains a first pressure-sensitive adhesive, a first branched crystalline polymer, and a foaming agent. The second pressure-sensitive adhesive layer contains a second pressure-sensitive adhesive and a second side chain crystalline polymer. The temporary fixing method of a workpiece according to the present invention includes a step of applying the temporary fixing double-sided adhesive tape to a predetermined temperature to peel the processed product from the pedestal together with the temporary fixing double-sided adhesive tape. And a step of peeling the workpiece from the double-sided adhesive tape for temporary fixing by heating to a predetermined temperature.

Description

Temporary fixing double-sided adhesive tape and temporary fixing method of workpiece using the same {TEMPORARY FIXING DOUBLE-SIDED ADHESIVE TAPE AND TEMPORARY FIXING METHOD FOR WORKPIECE USING SAME}

The present invention relates to a double-sided adhesive tape for temporarily fixing a work piece on a pedestal and a method for temporarily fixing a work piece using the same.

As a temporary fixing means for temporarily fixing a workpiece on a pedestal, a wax is known (see, for example, Patent Document 1).

However, if the workpiece is temporarily fixed on the pedestal through wax, since the wax remains, respectively, the workpiece and the pedestal when the workpiece is peeled from the pedestal, a washing process using an organic solvent or the like is required.

On the other hand, as another temporary fixing means, a double-sided adhesive tape is known. As a double-sided adhesive tape, a double-sided adhesive tape (A) is known in which the pressure-sensitive adhesive layer on one side is a general acrylic pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer on the other side is a foamed pressure-sensitive adhesive layer in which a foaming agent is added to a common acrylic pressure-sensitive adhesive layer.

In the double-sided adhesive tape (A), an acrylic pressure-sensitive adhesive layer is attached to a pedestal, and a foamed pressure-sensitive adhesive layer is attached to a workpiece to temporarily fix the workpiece on the pedestal. Peeling of the double-sided adhesive tape (A) is performed in the following procedure. First, after polishing the object to be processed or the like, the double-sided adhesive tape (A) is heated to a temperature at which the foaming agent expands or foams, thereby lowering the adhesive strength of the foamed adhesive layer. Next, after peeling the object to be processed from the double-sided adhesive tape (A), the double-sided adhesive tape (A) is peeled from the pedestal.

However, when such a double-sided adhesive tape (A) is used, there is a problem that the unevenness derived from the foaming agent is transferred to the workpiece during polishing or the like, and the yield is lowered.

Further, as another double-sided adhesive tape, a double-sided adhesive tape (B) is known in which the pressure-sensitive adhesive layer on one side is a general acrylic pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer on the other side is a temperature-sensitive adhesive layer. The temperature-sensitive adhesive layer is a pressure-sensitive adhesive layer containing a pressure-sensitive adhesive and a side-chain crystalline polymer, and the adhesive strength decreases at a temperature equal to or higher than the melting point of the side-chain crystalline polymer.

In the double-sided adhesive tape (B), an acrylic pressure-sensitive adhesive layer is attached to a pedestal, and a temperature sensitive pressure-sensitive adhesive layer is attached to a workpiece to temporarily fix the workpiece on the pedestal. Peeling of the double-sided adhesive tape (B) is performed in the following procedure. First, after polishing the work or the like, the work is peeled off from the pedestal together with the double-sided adhesive tape (B). Next, the double-sided adhesive tape (B) is heated to a temperature equal to or higher than the melting point of the side chain crystalline polymer to lower the adhesive strength of the temperature-sensitive adhesive layer, and the workpiece is peeled from the double-sided adhesive tape (B).

However, when such a double-sided adhesive tape (B) is used, since the peelability when peeling the workpiece together with the double-sided adhesive tape (B) from the pedestal is poor, for example, a spatula is used between the acrylic adhesive layer and the pedestal. It is necessary to form a separation starting point by inserting it into the interface. In addition, there is a problem in that the work piece is damaged due to an external force applied when forming the peeling starting point and the yield is lowered.

Japanese Patent Laid-Open No. Hei 6-69324

An object of the present invention is to provide a double-sided adhesive tape for temporary fixing that can easily peel off a work piece with good yield, and a method for temporarily fixing a work piece using the same.

The double-sided adhesive tape for temporary fixation of the present invention includes a film-like substrate, a first adhesive layer laminated on one side of the substrate and attached to the pedestal, and a second adhesive layer laminated on the other side of the substrate and attached to the workpiece. In addition, the first pressure-sensitive adhesive layer contains a first pressure-sensitive adhesive, a first side-chain crystalline polymer and a foaming agent, and the adhesive strength decreases at a temperature equal to or higher than the melting point of the first side-chain crystalline polymer, and the second The pressure-sensitive adhesive layer contains the second pressure-sensitive adhesive and the second side chain crystalline polymer, and the adhesive strength decreases at a temperature equal to or higher than the melting point of the second side chain crystalline polymer.

In the temporary fixing method of the work piece of the present invention, in a state in which the work piece is temporarily fixed on the pedestal through the double-sided adhesive tape for temporary fixing of the present invention, the double-sided adhesive tape for temporary fixing is applied to the melting point of the first side chain crystalline polymer. And heating the foaming agent to a temperature at which the foaming agent expands or foams, and peeling the workpiece from the pedestal together with the temporary fixing double-sided adhesive tape, and the second side chain crystalline polymer Heating to a temperature equal to or higher than the melting point of, and peeling the workpiece from the double-sided adhesive tape for temporary fixing.

(Effects of the Invention)

Advantageous Effects of Invention According to the present invention, there is an effect that an object to be processed can be easily peeled with good yield.

1 is a schematic explanatory view showing a double-sided adhesive tape for temporary fixing according to an embodiment of the present invention.
2 is a process chart showing a method of temporarily fixing a workpiece according to an embodiment of the present invention (a) to (c).

<Double sided adhesive tape for temporary fixing>

Hereinafter, a double-sided adhesive tape for temporary fixing according to an embodiment of the present invention (hereinafter, sometimes referred to as "tape") will be described in detail with reference to FIG. 1.

As shown in FIG. 1, the tape 1 of the present embodiment is different from the base material 2, the first adhesive layer 3 laminated on one side 21 of the base material 2, and the base material 2. It has the 2nd adhesive layer 4 laminated|stacked on the surface 22.

(materials)

The base material 2 of this embodiment is a film shape. The film form is not limited only to the film form, and is a concept including a film form or a sheet form as long as the effect of the present embodiment is not impaired.

As a constituent material of the substrate 2, for example, polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer Synthetic resins, such as coalescence and polyvinyl chloride, are mentioned. Among the synthetic resins exemplified, polyethylene terephthalate is preferable.

The base material 2 of this embodiment may be a monolayer body or a multilayer body, and the thickness is preferably 5 to 250 µm, more preferably 12 to 188 µm, and even more preferably 25 to 100 µm. Do. To increase the adhesion to the first adhesive layer 3 and the second adhesive layer 4 on one side 21 and the other side 22 of the substrate 2, for example, corona discharge treatment, plasma treatment, blasting Surface treatment, such as treatment, chemical etching treatment, and primer treatment, can be performed.

(First adhesive layer)

The first pressure-sensitive adhesive layer 3 laminated on one side 21 of the substrate 2 has an adherend as a base, and contains a first pressure-sensitive adhesive, a first side chain crystalline polymer, and a foaming agent.

The first pressure-sensitive adhesive is a polymer having adhesiveness, and specific examples thereof include natural rubber adhesives, synthetic rubber adhesives, styrene/butadiene latex-based adhesives, acrylic adhesives, and the like, of which acrylic adhesives are preferred.

As a monomer constituting the acrylic adhesive, for example, an alkyl group having 1 to 12 carbon atoms such as 2-ethylhexyl (meth)acrylate, methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate. Having (meth)acrylate; And (meth)acrylates having a hydroxyalkyl group such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxyhexyl (meth)acrylate. These may be used alone or in combination of two or more. (Meth)acrylate shall mean acrylate or methacrylate.

As a specific composition of an acrylic adhesive, a copolymer obtained by polymerizing 2-ethylhexyl acrylate, methyl acrylate, and 2-hydroxyethyl acrylate, etc. are mentioned. In addition, each of the above-described monomers is polymerized in a ratio of 42 to 62 parts by weight of 2-ethylhexyl acrylate, 30 to 50 parts by weight of methyl acrylate, and 3 to 13 parts by weight of 2-hydroxyethyl acrylate. desirable.

The polymerization method is not particularly limited, and for example, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method, or the like can be employed. In the case of employing a solution polymerization method, the above-described monomer may be mixed with a solvent and stirred at about 40 to 90°C for about 2 to 10 hours.

The weight average molecular weight of the polymer obtained by polymerizing the above-described monomer, that is, the first pressure-sensitive adhesive, is preferably 150,000 to 500,000, and more preferably 200,000 to 350,000. Thereby, when the tape 1 is peeled from the pedestal, it is possible to suppress the occurrence of so-called adhesive residues, where the first adhesive layer 3 remains on the pedestal. In addition, the cohesive force of the first pressure-sensitive adhesive layer 3 is too high, so that the lowering of the pressure-sensitive adhesive force of the first pressure-sensitive adhesive layer 3 can be suppressed. The weight average molecular weight is a value obtained by measuring a polymer by gel permeation chromatography (GPC) and converting the obtained measured value into polystyrene.

On the other hand, the first side chain crystalline polymer is a polymer having a melting point. The melting point is the temperature at which a specific part of the polymer, which was initially adjusted in an orderly arrangement by a certain equilibrium process, becomes disordered, and the value obtained by measuring with a differential thermal scanning calorimeter (DSC) under the measurement condition of 10°C/min. It is said to mean.

The first branched crystalline polymer crystallizes at a temperature less than the above-described melting point, and exhibits fluidity by performing phase dislocation at a temperature above the melting point. That is, the first side chain crystalline polymer has a temperature sensitivity that reversibly causes a crystal state and a flow state in response to a temperature change. Accordingly, at a temperature lower than the melting point, the first side-chain crystalline polymer is in a crystalline state, so that the first pressure-sensitive adhesive layer 3 can secure adhesive strength. Further, at a temperature equal to or higher than the melting point, the first side-chain crystalline polymer exhibits fluidity, thereby inhibiting the adhesiveness of the first pressure-sensitive adhesive, and consequently lowering the adhesive force of the first pressure-sensitive adhesive layer 3.

The melting point of the first side chain crystalline polymer is preferably 45°C or more and less than 55°C. Accordingly, since the first side-chain crystalline polymer is in a crystalline state at room temperature (23° C.), the first pressure-sensitive adhesive layer 3 can secure adhesive strength at room temperature, and consequently improve workability.

The melting point described above can be adjusted by changing the composition of the first side chain crystalline polymer. As a monomer constituting the first side-chain crystalline polymer, for example, (meth)acrylate having a straight-chain alkyl group having 16 or more carbon atoms, (meth)acrylate having an alkyl group having 1 to 6 carbon atoms, polar monomers, etc. have.

Examples of the (meth)acrylate having a linear alkyl group having 16 or more carbon atoms include cetyl (meth)acrylate, stearyl (meth)acrylate, eicosyl (meth)acrylate, behenyl (meth)acrylate, etc. (Meth)acrylate having a linear alkyl group having 16 to 22 carbon atoms, and examples of the (meth)acrylate having an alkyl group having 1 to 6 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylic Acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, and the like. Examples of polar monomers include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and the like. Ethylenically unsaturated monomers; Ethylenically unsaturated monomers having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxyhexyl (meth)acrylate, and the like. You may use a kind or a mixture of two or more kinds.

The first side-chain crystalline polymer is preferably a polymer obtained by polymerizing a (meth)acrylate having a linear alkyl group having at least 16 carbon atoms, preferably 18 or more carbon atoms, among the above-described monomers. Each of the above-described monomers is, for example, 30 to 100 parts by weight of (meth)acrylate having a linear alkyl group having 16 or more carbon atoms, 0 to 70 parts by weight of (meth)acrylate having an alkyl group having 1 to 6 carbon atoms, It is preferable to polymerize the polar monomer at a ratio of 0 to 10 parts by weight.

As a specific composition of the first side chain crystalline polymer, a copolymer obtained by polymerizing behenyl acrylate, stearyl acrylate, methyl acrylate, and acrylic acid, and the like can be given. In addition, each of the above-described monomers is a ratio of 35 to 45 parts by weight of behenyl acrylate, 30 to 40 parts by weight of stearyl acrylate, 15 to 25 parts by weight of methyl acrylate, and 1 to 10 parts by weight of acrylic acid. It is preferred to polymerize.

The polymerization method is not particularly limited, and for example, a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method, or the like can be employed. In the case of employing a solution polymerization method, the above-described monomer may be mixed with a solvent and stirred at about 40 to 90°C for about 2 to 10 hours.

The weight average molecular weight of the first side-chain crystalline polymer is preferably 3,000 to 30,000, more preferably 5,000 to 20,000, and even more preferably 6,000 to 11,000. Accordingly, when the tape 1 is peeled from the pedestal, it is possible to suppress the occurrence of adhesive residues. Further, when the first side chain crystalline polymer exhibits fluidity at a temperature equal to or higher than the melting point, the adhesive force of the first pressure-sensitive adhesive layer 3 can be sufficiently reduced. The weight average molecular weight is a value obtained by measuring the first side chain crystalline polymer by GPC, and converting the obtained measured value into polystyrene.

The first side chain crystalline polymer is preferably blended in a ratio of 0.5 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the first pressure-sensitive adhesive in terms of solid content. Accordingly, when the first side chain crystalline polymer exhibits fluidity at a temperature equal to or higher than the melting point, the adhesive strength of the first pressure-sensitive adhesive layer 3 can be sufficiently reduced.

On the other hand, as the foaming agent, both general chemical foaming agents and physical foaming agents can be employed. Chemical foaming agents include thermally decomposable and reactive organic foaming agents and inorganic foaming agents.

Examples of thermally decomposable organic foaming agents include various azo compounds (such as azodicarbonamide), nitroso compounds (such as N,N'-dinitrosopentamethylenetetramine), and hydrazine derivatives [4,4'-oxybis. (Benzenesulfonylhydrazide), etc.], semicarbazide compounds (hydrazodicarbonamide, etc.), azide compounds, tetrazole compounds, and the like. Examples of reactive organic foaming agents include isocyanate compounds, etc. Can be lifted.

Examples of the thermally decomposable inorganic foaming agent include bicarbonate and carbonate (sodium hydrogen carbonate, etc.), nitrite and hydride, and the reactive inorganic foaming agent include, for example, combining sodium bicarbonate and acid, and hydrogen peroxide and yeast. The bacteria are combined, and zinc powder and acid are combined.

Examples of the physical foaming agent include organic physical foaming agents such as aliphatic hydrocarbons such as butane, pentane, and hexane, hydrogen chloride such as dichloroethane and dichloromethane, and fluorochlorohydrocarbons such as Fron; Inorganic physical foaming agents, such as air, carbon dioxide gas, and nitrogen gas, etc. are mentioned.

Further, as another foaming agent, a so-called microballoon foaming agent, which is microencapsulated thermally expandable fine particles, can be employed. The microballoon foaming agent is obtained by encapsulating a heat-expandable material made of a solid, liquid or gas inside a polymer shell made of a thermoplastic or thermosetting resin. In other words, the microballoon blowing agent includes a hollow polymer shell having an average particle diameter of micro-order and a heat expandable material enclosed in the polymer shell. The volume of the microballoon foaming agent expands to 40 times or more by heating, and a closed-cell foam is obtained. Therefore, the microballoon foaming agent has a characteristic that the foaming ratio is considerably increased compared to the general foaming agent. Commercially available ones can be used for such microballoon foaming agents, and for example, "461DU20" manufactured by Expancel is preferable.

The foaming agent is preferably blended in a ratio of 5 to 30 parts by weight based on 100 parts by weight of the first pressure-sensitive adhesive in terms of solid content, more preferably 10 to 30 parts by weight. Accordingly, when the foaming agent is expanded or foamed, the adhesive force of the first pressure-sensitive adhesive layer 3 can be sufficiently reduced.

The temperature at which the blowing agent expands or foams is usually higher than the melting point of the first branched crystalline polymer. In addition, the temperature at which the blowing agent expands or foams is usually 180°C or less, and it is preferable to start expansion or foaming at 90°C to substantially completely foam at 120°C.

Although it does not specifically limit as the average particle diameter of a foaming agent, It is preferable that it is usually 5-50 micrometers, it is more preferable that it is 5-20 micrometers, and it is still more preferable that it is 5-10 micrometers. The average particle diameter is a value obtained by measuring with a particle size distribution measuring device.

In order to laminate the first pressure-sensitive adhesive layer 3 containing the above-described first pressure-sensitive adhesive and the first side-chain crystalline polymer on one side 21 of the substrate 2 together with such a foaming agent, for example, a first pressure-sensitive adhesive A coating liquid obtained by adding an adhesive, a first side chain crystalline polymer, and a foaming agent to a solvent may be applied to one side 21 of the substrate 2 by a coater or the like and dried. As a coater, a knife coater, a roll coater, a calender coater, a comma coater, a gravure coater, a rod coater, etc. are mentioned, for example.

The thickness of the first pressure-sensitive adhesive layer 3 is preferably 10 to 50 µm, more preferably 10 to 30 µm, and still more preferably 15 to 25 µm.

In addition, various additives such as a crosslinking agent, a tackifier, a plasticizer, an anti-aging agent, and an ultraviolet absorber may be added to the first pressure-sensitive adhesive layer 3, and it is preferable to add a crosslinking agent among the exemplified additives. As a crosslinking agent, an isocyanate compound etc. are mentioned, for example. The crosslinking agent is preferably added in a ratio of 0.1 to 10 parts by weight based on 100 parts by weight of the first pressure-sensitive adhesive in terms of solid content, more preferably 0.1 to 5 parts by weight, and 0.1 to 2 parts by weight. It is more preferable to do it.

Particularly preferred combinations of the first pressure-sensitive adhesive, the first side-chain crystalline polymer, the foaming agent, and the crosslinking agent in the above-described first pressure-sensitive adhesive layer 3 are in weight ratio, and the first pressure-sensitive adhesive: first side-chain crystalline polymer: The ratio of foaming agent: crosslinking agent = 100:1-3:10-15:0.5-1 is mentioned.

(2nd adhesive layer)

The second pressure-sensitive adhesive layer 4 laminated on the other side 22 of the above-described substrate 2 is a workpiece, contains a second pressure-sensitive adhesive and a second side-chain crystalline polymer, and a second side-chain crystal It is a temperature-sensitive adhesive layer whose adhesive strength decreases at a temperature above the melting point of the polymer.

It is preferable that the second pressure-sensitive adhesive has a weight average molecular weight greater than the weight average molecular weight of the first pressure-sensitive adhesive described above. Accordingly, the cohesive force of the second pressure-sensitive adhesive layer 4 is improved than that of the first pressure-sensitive adhesive layer 3, so that the holding force for holding the workpiece is improved, and as a result, the workpiece can be peeled off from the pedestal together with the tape 1 In this case, it is possible to prevent the workpiece from falling off from the tape 1.

The weight average molecular weight of the second pressure-sensitive adhesive is preferably 300,000 to 700,000, more preferably 400,000 to 600,000, and within this numerical range, the weight average molecular weight of the second pressure-sensitive adhesive is adjusted to that of the first pressure-sensitive adhesive. It is preferable to make it larger than the weight average molecular weight. Accordingly, the above-described effect can be obtained while suppressing the occurrence of adhesive residue when the workpiece is peeled from the tape 1.

The composition of the second pressure-sensitive adhesive may be the same as or different from the first pressure-sensitive adhesive described above.

Other configurations of the second pressure-sensitive adhesive are the same as those of the above-described first pressure-sensitive adhesive, and description thereof will be omitted.

On the other hand, it is preferable that the melting point of the second side-chain crystalline polymer is 45°C or more and less than 55°C, similar to the above-described first side-chain crystalline polymer. Further, the weight average molecular weight of the second side chain crystalline polymer is preferably 3,000 to 30,000, more preferably 5,000 to 20,000, and still more preferably 6,000 to 11,000. The second side chain crystalline polymer is preferably blended in a ratio of 0.5 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the second pressure-sensitive adhesive in terms of solid content.

The melting point, composition, weight average molecular weight, blending amount, and the like of the second branched crystalline polymer may be the same as or different from the above-described first branched crystalline polymer.

Other configurations of the second side chain crystalline polymer are the same as those of the above-described first side chain crystalline polymer, and thus a description thereof will be omitted.

It is preferable that the thickness of the second pressure-sensitive adhesive layer 4 containing the second pressure-sensitive adhesive and the second side-chain crystalline polymer is smaller than that of the first pressure-sensitive adhesive layer 3 described above. In other words, it is preferable that the thickness of the first pressure-sensitive adhesive layer 3 is larger than that of the second pressure-sensitive adhesive layer 4. In this embodiment, the thickness of the 1st adhesive layer 3 is comprised larger than the thickness of the 2nd adhesive layer 4. According to this configuration, when the workpiece is pressed against the pedestal through the tape 1, the thick first adhesive layer 3 attached to the pedestal is widened according to the surface shape of the pedestal, thereby increasing the contact area. It can stabilize the temporarily fixed state of the workpiece. In addition, since the second thin adhesive layer 4 adhered to the workpiece becomes difficult to be pushed out from the outer circumference of the tape 1, contamination of the workpiece by the excess second adhesive layer 4 that has been pushed out can be suppressed. I can.

The thickness of the second pressure-sensitive adhesive layer 4 is preferably 5 to 40 μm, more preferably 5 to 20 μm, still more preferably 5 to 15 μm, and within this numerical range, the first pressure-sensitive adhesive layer 3 It is preferable to make the thickness of) larger than the thickness of the second adhesive layer 4.

Moreover, it is preferable to add a crosslinking agent to the 2nd adhesive layer 4 like the 1st adhesive layer 3. The crosslinking agent is preferably added in a ratio of 0.1 to 10 parts by weight based on 100 parts by weight of the second pressure-sensitive adhesive in terms of solid content, more preferably 0.1 to 5 parts by weight, and 0.1 to 1 part by weight. It is more preferable to do it.

As a particularly preferable combination of the second pressure-sensitive adhesive, the second side-chain crystalline polymer, and the crosslinking agent in the second pressure-sensitive adhesive layer 4 described above, these are in a weight ratio: the second pressure-sensitive adhesive: second side-chain crystalline polymer: crosslinker = 100 The ratio of :1-5:0.4-0.6 is mentioned.

Other configurations of the second pressure-sensitive adhesive layer 4 are the same as those of the first pressure-sensitive adhesive layer 3 described above, and a description thereof is omitted.

The tape 1 of this embodiment described above is laminated on the first separator 5 laminated on the surface 31 of the first adhesive layer 3 and on the surface 41 of the second adhesive layer 4 A second separator 6 is further provided. Accordingly, the surface 31 of the first adhesive layer 3 and the surface 41 of the second adhesive layer 4 can be respectively protected.

Examples of the first separator 5 and the second separator 6 include those obtained by coating a release agent such as silicone or fluorine on the surface of a film made of polyethylene, polyethylene terephthalate, or the like. In addition, the thickness of each of the first separator 5 and the second separator 6 is preferably 10 to 110 µm.

The first separator 5 and the second separator 6 may have the same composition, thickness, etc. or different from each other. In this embodiment, the first separator 5 is a polyethylene film coated with silicone on the surface, and the second separator 6 is a polyethylene terephthalate film coated with silicone. In addition, in the present embodiment, the thickness of the first separator 5 is larger than that of the second separator 6.

In the tape 1 of the present embodiment, the 180° peeling strength of the first adhesive layer 3 at 23°C is preferably 2 to 16 N/25 mm, and more preferably 6 to 12 N/25 mm. Accordingly, it is possible to obtain a fixing force to the pedestal. The 180° peeling strength of the first pressure-sensitive adhesive layer 3 is a value obtained by measuring the 180° peeling strength of the polyethylene terephthalate film at an ambient temperature of 23°C according to JIS Z0237.

In addition, in the tape 1 of the present embodiment, the 180° peel strength of the second adhesive layer 4 at 23° C. is preferably 0.5 to 10 N/25 mm, more preferably 1 to 3.5 N/25 mm. . Accordingly, it is possible to obtain a fixing force for a workpiece such as sapphire glass. The 180° peeling strength of the second pressure-sensitive adhesive layer 4 is a value obtained by measuring the 180° peeling strength of the sapphire glass at an ambient temperature of 23°C according to JIS Z0237.

<Method of temporarily fixing the workpiece>

Next, a method of temporarily fixing a workpiece according to an embodiment of the present invention will be described in detail with reference to FIG. 2, taking the case of using the tape 1 described above as an example.

In this embodiment, first, from a state in which the workpiece 200 is temporarily fixed on the pedestal 100 through the tape 1 as shown in Fig. 2(a), as shown in Fig. 2(b), (200) is peeled off from the pedestal 100 together with the tape 1.

Specifically, a desired one can be adopted as the workpiece 200, and although it is not particularly limited, sapphire glass, which is a material for the LED substrate, is preferable. The workpiece 200 of this embodiment is sapphire glass. In addition, as the pedestal 100, for example, a ceramic one may be mentioned.

As shown in FIG. 2(a), the workpiece 200 is a tape in a state in which the first adhesive layer 3 is attached to the pedestal 100 and the second adhesive layer 4 is attached to the workpiece 200. Through 1), it is temporarily fixed on the pedestal 100. Accordingly, even when the workpiece 200 is polished, it is possible to suppress a decrease in yield due to transfer of irregularities derived from the foaming agent to the workpiece 200.

Then, the tape 1 is heated to a temperature equal to or higher than the melting point of the above-described first branched crystalline polymer and at which the blowing agent expands or foams. Accordingly, the first side-chain crystalline polymer exhibits fluidity at a temperature equal to or higher than the melting point, and the foaming agent expands or foams, so that the adhesive strength of the first pressure-sensitive adhesive layer 3 can be sufficiently reduced. As a result, as shown in Fig. 2(b), the workpiece 200 can be smoothly peeled from the pedestal 100 together with the tape 1 in the direction of the arrow (A). Therefore, the external force increases during peeling. It is possible to suppress a decrease in yield due to damage to the workpiece 200. As a heating means for heating the tape 1, a heater or the like is mentioned, for example.

In addition, as the adhesive strength of the first pressure-sensitive adhesive layer 3 decreases, the second pressure-sensitive adhesive layer 4 also usually reaches a temperature equal to or higher than the melting point of the contained second side-chain crystalline polymer, and the adhesive strength decreases. Since it is not completely lost, the workpiece 200 can be continuously fixed by the second pressure-sensitive adhesive layer 4 unless a large external force is applied.

After peeling the workpiece 200 together with the tape 1 from the pedestal 100, the tape 1 is heated to a temperature equal to or higher than the melting point of the second side-chain crystalline polymer to reduce the adhesive strength of the second adhesive layer 4 Then, as shown in Fig. 2(c), the workpiece 200 is peeled from the tape 1 in the direction of the arrow B. At this time, according to the tape 1, since it is difficult to generate an adhesive residue on the workpiece 200, the cleaning process can be simplified or omitted.

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. In addition, in the following description, "part" means a weight part.

(Synthesis Example 1: First Pressure-sensitive Adhesive)

52 parts of 2-ethylhexyl acrylate, 40 parts of methyl acrylate, 8 parts of 2-hydroxyethyl acrylate, and 200 parts of toluene in a ratio of 0.3 parts of perbutyl ND (manufactured by NOF Corporation) as a polymerization initiator It was added and stirred at 60° C. for 5 hours to polymerize these monomers. The weight average molecular weight of the obtained copolymer was 250,000.

(Synthesis Example 2: Second Pressure Sensitive Adhesive)

The temperature at the time of stirring was set to 55°C instead of 60°C, 0.2 parts of perbutyl ND (manufactured by NOF Corporation) instead of 0.3 parts, and ethyl acetate:heptane = 7:3 (weight ratio) instead of toluene as the solvent. In the same manner as in Synthesis Example 1 except for polymerization, 2-ethylhexyl acrylate, methyl acrylate and 2-hydroxyethyl acrylate were polymerized. The weight average molecular weight of the obtained copolymer was 450,000.

(Synthesis Example 3: 1st, 2nd side chain crystalline polymer)

40 parts of behenyl acrylate, 35 parts of stearyl acrylate, 20 parts of methyl acrylate, 5 parts of acrylic acid, 6 parts of dodecylmercaptan as a chain transfer agent, and Perhexyl PV (manufactured by NOF Corporation) as a polymerization initiator ) Was added to 100 parts of toluene in a ratio of 1.0 part, and stirred at 80°C for 5 hours to polymerize these monomers. The weight average molecular weight of the obtained copolymer was 8,000, and the melting point was 50°C.

Table 1 shows each copolymer of Synthesis Examples 1 to 3. In addition, the weight average molecular weight was obtained by measuring the copolymer by GPC, and converting the obtained measured value into polystyrene. The melting point was obtained by measuring the copolymer in DSC under the measurement conditions of 10°C/min.

(Example)

<Production of double-sided adhesive tape>

First, each copolymer obtained in Synthesis Examples 1 to 3, a foaming agent, and a crosslinking agent were mixed in the combination shown in Table 2 to obtain a mixture. In Table 2, the ratio shows the weight ratio in terms of solid content.

The relationship between each copolymer obtained in Synthesis Examples 1 to 3, the first and second pressure-sensitive adhesives in Table 2, and the first and second side chain crystalline polymers are as follows.

First Pressure Sensitive Adhesive: Synthesis Example 1

Second Pressure Sensitive Adhesive: Synthesis Example 2

First side chain crystalline polymer: Synthesis Example 3

Second side chain crystalline polymer: Synthesis Example 3

The foaming agent and crosslinking agent used are as follows.

Foaming agent: Microballoon foaming agent "461DU20" manufactured by Expancel with an average particle diameter of 6 to 9 μm and a foaming start temperature of 90°C or higher

Crosslinking agent: Nippon Polyurethane Industry Co., Ltd. Production of isocyanate compound "CORONATE L-45E"

Next, the obtained mixture was adjusted so that the solid content was 30% by weight with ethyl acetate to obtain a coating liquid. Then, the obtained coating solution was applied to a film-like substrate made of polyethylene terephthalate having a thickness of 100 µm and dried to obtain a double-sided adhesive tape. Drying was performed for each 1st, 2nd adhesive layer using a heater. Drying conditions are as follows.

First adhesive layer: 80℃×10min

2nd adhesive layer: 100℃×10min

In the obtained double-sided adhesive tape, the thickness of each of the first and second adhesive layers is as follows.

Thickness of the first adhesive layer: 20 μm

Thickness of the second adhesive layer: 10 μm

<Evaluation>

About the obtained double-sided adhesive tape, peel strength, foam peelability, adhesive residual property, and abrasion property were evaluated. Each evaluation method is shown below, and the result is shown in Table 2.

(Peel strength)

The 180° peel strength of the first and second pressure-sensitive adhesive layers at 23° C. ambient temperature was evaluated. First, at an ambient temperature of 23°C, the first pressure-sensitive adhesive layer was made upward, and the second pressure-sensitive adhesive layer was fixed to the stainless steel sheet through a commercial double-sided tape. Next, a 25 µm-thick polyethylene terephthalate film was attached to the first pressure-sensitive adhesive layer. Then, the polyethylene terephthalate film was peeled 180° from the first pressure-sensitive adhesive layer at a rate of 300 mm/min using a load cell. The 180° peeling strength at this time was measured based on JIS Z0237, and the 180° peeling strength of the first pressure-sensitive adhesive layer at an ambient temperature of 23°C was evaluated. The 180° peel strength of the second adhesive layer at 23°C is the same as that of the first adhesive layer, except that the double-sided adhesive tape was attached to the sapphire glass through the second adhesive layer, and the double-sided adhesive tape was peeled 180° from the sapphire glass. Evaluated by the method. Each evaluation result is shown in the column of "peel strength" in Table 2, respectively.

(Foaming peelability)

First, at an ambient temperature of 23°C, a double-sided adhesive tape was attached to the ceramic plate through the first adhesive layer. Subsequently, the ambient temperature was raised to 130°C, which is a temperature equal to or higher than the melting point of the first side chain crystalline polymer and the temperature at which the foaming agent expands or foams. At this time, it was visually observed whether the double-sided adhesive tape was peeled from the ceramic plate only by its own weight. In addition, the evaluation criteria were set as follows.

○: It peeled within 120 seconds.

(Triangle|delta): It exceeded 120 seconds, and it peeled within 300 seconds.

X: It did not peel within 300 seconds.

(Adhesive residual property)

First, in an atmosphere temperature of 23°C, each side of the double-sided adhesive tape was attached to a sapphire glass. Subsequently, for the first pressure-sensitive adhesive layer, the double-sided adhesive tape was peeled off at an atmospheric temperature of 130°C, and for the second pressure-sensitive adhesive layer, the double-sided pressure-sensitive adhesive tape was peeled off at an atmospheric temperature of 60°C. And the adhesive residual property (residue) was evaluated by visually observing the surface of the sapphire glass after peeling. In addition, the evaluation criteria were set as follows.

(Circle): Although some adhesive residue (residue) was observed on the sapphire glass, it was a range without a problem in practical use.

?: An adhesive residue (residue) was observed on the sapphire glass.

×: A large amount of adhesive residue (residue) was observed on the sapphire glass.

(Abrasive)

First, at an ambient temperature of 23°C, a double-sided adhesive tape was attached to the base of the polishing machine through the first adhesive layer. Subsequently, a plate-like work made of sapphire glass having a thickness of 635 μm was attached to the double-sided adhesive tape through the second adhesive layer. And the polishing conditions were set as follows.

Grinding machine: plate size 36 inches

Polishing pressure: 170kgf/axis

Plate rotation speed: 45rpm

Slurry: colloidal silica

Polishing cloth: Non-woven type

Atmosphere temperature: 23℃

Exothermic temperature range during polishing: 23~45℃

Under the above polishing conditions, the workpiece was polished to a thickness of 620 μm. At this time, the polishing property was evaluated by visually observing whether or not a shift occurred in the first and second pressure-sensitive adhesive layers. In addition, visual observation was performed during or after polishing. In addition, the evaluation criteria were set as follows.

(Circle): There was no shift in either of the 1st and 2nd adhesive layers.

X: A shift occurred in at least one of the first and second adhesive layers.

Claims (12)

A film-like substrate, and
A first adhesive layer laminated on one side of the substrate and adhered to the pedestal,
It has a second pressure-sensitive adhesive layer laminated on the other side of the substrate and adhered to the workpiece,
The first pressure-sensitive adhesive layer contains a first pressure-sensitive adhesive, a first side-chain crystalline polymer, and a foaming agent, and the adhesive strength decreases at a temperature equal to or higher than the melting point of the first side-chain crystalline polymer,
The second pressure-sensitive adhesive layer contains the second pressure-sensitive adhesive and the second side-chain crystalline polymer, and the adhesive strength decreases at a temperature equal to or higher than the melting point of the second side-chain crystalline polymer,
The weight average molecular weight of the second pressure-sensitive adhesive is greater than the weight average molecular weight of the first pressure-sensitive adhesive. delete The method of claim 1,
The thickness of the first adhesive layer is a double-sided adhesive tape for temporary fixing, characterized in that greater than the thickness of the second adhesive layer. The method of claim 1,
The first pressure-sensitive adhesive and the second pressure-sensitive adhesive are a copolymer obtained by polymerizing 2-ethylhexyl acrylate, methyl acrylate, and 2-hydroxyethyl acrylate. The method of claim 1,
The first side-chain crystalline polymer and the second side-chain crystalline polymer are polymers obtained by polymerizing a (meth)acrylate having a linear alkyl group having at least 16 carbon atoms or more. The method of claim 1,
The first side-chain crystalline polymer and the second side-chain crystalline polymer are copolymers obtained by polymerizing behenyl acrylate, stearyl acrylate, methyl acrylate, and acrylic acid. The method of claim 1,
The melting point of the first side chain crystalline polymer and the melting point of the second side chain crystalline polymer are both 45°C or more and less than 55°C. The method of claim 1,
The foaming agent is a double-sided adhesive tape for temporary fixation, wherein the foaming agent is a microballoon foaming agent comprising a hollow polymer shell having an average particle diameter of micro-order and a heat-expandable material enclosed in the polymer shell. The method of claim 1,
The first pressure-sensitive adhesive layer has a 180° peel strength of 2 to 16 N/25 mm with respect to the polyethylene terephthalate film at an ambient temperature of 23° C.,
The second pressure-sensitive adhesive layer is a double-sided adhesive tape for temporary fixing, characterized in that the 180° peel strength of the sapphire glass at an ambient temperature of 23° C. is 0.5 to 10 N/25 mm. The method of claim 1,
A double-sided adhesive tape for temporary fixing, further comprising: a first separator laminated on the surface of the first pressure-sensitive adhesive layer and a second separator laminated on the surface of the second pressure-sensitive adhesive layer. In a state in which the workpiece is temporarily fixed on the pedestal through the double-sided adhesive tape for temporary fixing according to claim 1, the double-sided adhesive tape for temporary fixing is at a temperature equal to or higher than the melting point of the first side chain crystalline polymer, and the foaming agent expands or foams. Heating to a temperature, and peeling the workpiece together with the double-sided adhesive tape for temporary fixing from the pedestal,
And a step of heating the double-sided adhesive tape for temporary fixing to a temperature equal to or higher than the melting point of the second side-chain crystalline polymer, and peeling the workpiece from the double-sided adhesive tape for temporary fixing. The method of claim 11,
The method of temporarily fixing the workpiece, characterized in that the workpiece is sapphire glass.

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