JP6346170B2 - Double-sided adhesive tape for temporary fixing - Google Patents

Description

  The present invention relates to a temporary fixing double-sided pressure-sensitive adhesive tape for temporarily fixing a workpiece on a pedestal and a method for temporarily fixing a workpiece using the same.

Wax is known as a temporary fixing means for temporarily fixing a workpiece on a pedestal (see, for example, Patent Document 1).
However, if the work piece is temporarily fixed on the pedestal via the wax, the wax remains on the work piece and the pedestal when the work piece is peeled off from the pedestal, so a cleaning process using an organic solvent or the like is required. become.

  On the other hand, a double-sided adhesive tape is known as another temporary fixing means. As a double-sided adhesive tape, the adhesive layer on one side is a general acrylic adhesive layer, and the adhesive layer on the other side is a foamed adhesive layer obtained by adding a foaming agent to a general acrylic adhesive layer. A double-sided adhesive tape (A) is known.

The double-sided pressure-sensitive adhesive tape (A) is one in which an acrylic pressure-sensitive adhesive layer is attached to a pedestal and a foamed pressure-sensitive adhesive layer is attached to a work piece, and the work piece is temporarily fixed on the pedestal. The double-sided pressure-sensitive adhesive tape (A) is peeled according to the following procedure. First, after polishing the workpiece, the double-sided pressure-sensitive adhesive tape (A) is heated to a temperature at which the foaming agent expands or foams, thereby reducing the adhesive strength of the foamed adhesive layer. Next, after peeling a to-be-processed object from a double-sided adhesive tape (A), a double-sided adhesive tape (A) is peeled from a base.
However, when such a double-sided pressure-sensitive adhesive tape (A) is used, there is a problem that the unevenness derived from the foaming agent is transferred to the workpiece during the polishing process and the yield is lowered.

  In addition, as another double-sided pressure-sensitive adhesive tape, a double-sided pressure-sensitive adhesive tape (B) 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 pressure-sensitive adhesive layer is known. It has been. The temperature-sensitive pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer that contains a pressure-sensitive adhesive and a side chain crystalline polymer, and whose adhesive strength decreases at a temperature equal to or higher than the melting point of the side chain crystalline polymer.

  The double-sided pressure-sensitive adhesive tape (B) is one in which an acrylic pressure-sensitive adhesive layer is attached to a pedestal and a temperature-sensitive pressure-sensitive adhesive layer is attached to a work piece, and the work piece is temporarily fixed on the pedestal. The double-sided adhesive tape (B) is peeled according to the following procedure. First, after polishing the workpiece, the workpiece is peeled from the base together with the double-sided adhesive tape (B). Next, the double-sided pressure-sensitive adhesive tape (B) is heated to a temperature equal to or higher than the melting point of the side chain crystalline polymer to reduce the adhesive force of the temperature-sensitive pressure-sensitive adhesive layer, and the workpiece is peeled from the double-sided pressure-sensitive adhesive tape (B). To do.

  However, when such a double-sided pressure-sensitive adhesive tape (B) is used, the peelability when the work piece is peeled from the pedestal together with the double-sided pressure-sensitive adhesive tape (B) is poor. It is necessary to form a peeling start point by inserting it at the interface. And there existed a problem that a to-be-processed object was damaged by the external force added when forming a peeling start point, and a yield fell.

JP-A-6-69324

  An object of the present invention is to provide a temporary fixing double-sided pressure-sensitive adhesive tape that can easily peel off a workpiece with a high yield and a method of temporarily fixing a workpiece using the same.

  The double-sided pressure-sensitive adhesive tape for temporary fixing according to the present invention includes a film-like base material, a first pressure-sensitive adhesive layer that is laminated on one side of the base material, and is attached to a pedestal, and is laminated on the other side of the base material. A first pressure-sensitive adhesive, a first side-chain crystalline polymer, and a foaming agent, and the first pressure-sensitive adhesive layer includes a second pressure-sensitive adhesive layer that adheres to a workpiece. Adhesive strength decreases at a temperature equal to or higher than the melting point of the first side chain crystalline polymer, and the second pressure-sensitive adhesive layer contains a second pressure-sensitive adhesive and a second side chain crystalline polymer, and the second side chain The adhesive strength decreases at a temperature equal to or higher than the melting point of the crystalline polymer.

  The method for temporarily fixing the workpiece according to the present invention comprises the step of temporarily fixing the workpiece on the pedestal via the above-described temporary fixing double-sided adhesive tape of the present invention. Heating to a temperature equal to or higher than the melting point of the first side-chain crystalline polymer and 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; Heating the double-sided pressure-sensitive 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 pressure-sensitive adhesive tape for temporary fixation.

  According to the present invention, there is an effect that a workpiece can be easily peeled off with a high yield.

It is a schematic explanatory drawing which shows the double-sided adhesive tape for temporary fixing which concerns on one Embodiment of this invention. (A)-(c) is process drawing which shows the temporary fixing method of the to-be-processed object which concerns on one Embodiment of this invention.

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

  As shown in FIG. 1, the tape 1 of this embodiment is laminated | stacked on the other surface 22 of the base material 2, the 1st adhesive layer 3 laminated | stacked on the single side | surface 21 of the base material 2, and the base material 2. As shown in FIG. A second pressure-sensitive adhesive layer 4.

(Base material)
The base material 2 of this embodiment is a film form. The film shape is not limited to a film shape, and is a concept including a film shape or a sheet shape as long as the effects of the present embodiment are not impaired.

  Examples of the constituent material of the substrate 2 include polyethylene, polyethylene terephthalate, polypropylene, polyester, polyamide, polyimide, polycarbonate, ethylene vinyl acetate copolymer, ethylene ethyl acrylate copolymer, ethylene polypropylene copolymer, and polyvinyl chloride. Examples include synthetic resins, and among the exemplified synthetic resins, polyethylene terephthalate is preferable.

  The substrate 2 of the present embodiment may be either a single layer or a multilayer, and the thickness is preferably 5 to 250 μm, more preferably 12 to 188 μm, 25 More preferably, it is ˜100 μm. For improving the adhesion to the first pressure-sensitive adhesive layer 3 and the second pressure-sensitive adhesive layer 4 on one side 21 and the other side 22 of the substrate 2, for example, corona discharge treatment, plasma treatment, blast treatment, chemical etching treatment, primer Surface treatment such as treatment can be performed.

(First adhesive layer)
As for the 1st adhesive layer 3 laminated | stacked on the single side | surface 21 of the base material 2, a to-be-adhered body is a base, and contains a 1st pressure sensitive adhesive, a 1st side chain crystalline polymer, and a foaming agent.

  The first pressure sensitive adhesive is a tacky polymer, and specific examples thereof include natural rubber adhesives, synthetic rubber adhesives, styrene / butadiene latex base adhesives, acrylic adhesives, and the like. Of these, 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, butyl (meth) acrylate and the like. (Meth) acrylates having a hydroxyalkyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyhexyl (meth) acrylate, and the like. You may use 1 type or in mixture of 2 or more types. (Meth) acrylate means acrylate or methacrylate.

  Specific examples of the composition of the acrylic adhesive include a copolymer obtained by polymerizing 2-ethylhexyl acrylate, methyl acrylate and 2-hydroxyethyl acrylate. Moreover, it is preferable to polymerize each monomer mentioned above in the ratio which makes 2-ethylhexyl acrylate 42-62 weight part, methyl acrylate 30-50 weight part, and 2-hydroxyethyl acrylate 3-13 weight part.

  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 and the like can be employed. When the solution polymerization method is employed, the above-described monomer may be mixed in 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 monomers, 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 prevent the first adhesive layer 3 from remaining on the pedestal, so-called adhesive residue. Moreover, it can suppress that the cohesion force of the 1st adhesive layer 3 becomes high too much, and the adhesive force of the 1st adhesive layer 3 becomes low. The weight average molecular weight is a value obtained by measuring the polymer by gel permeation chromatography (GPC) and converting the obtained measurement value to polystyrene.

  On the other hand, the first side chain crystalline polymer is a polymer having a melting point. The melting point is a temperature at which a specific portion of the polymer that was initially aligned in an ordered arrangement becomes disordered by an equilibrium process, and is measured at 10 ° C./min by a differential thermal scanning calorimeter (DSC). It shall mean the value obtained by measurement.

  The first side chain crystalline polymer is crystallized at a temperature lower than the melting point described above, and undergoes phase transition and exhibits fluidity at a temperature higher than the melting point. That is, the first side chain crystalline polymer has temperature sensitivity that reversibly causes a crystalline state and a fluid state in response to a temperature change. Thereby, since the 1st side chain crystalline polymer exists in a crystalline state at the temperature below melting | fusing point, the 1st adhesive layer 3 can ensure adhesive force. 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 described above, resulting in a decrease in the adhesive strength of the first adhesive layer 3. Can be made.

  The melting point of the first side chain crystalline polymer is preferably 45 ° C or higher and lower than 55 ° C. Thereby, since the 1st side chain crystalline polymer exists in a crystalline state at room temperature (23 degreeC), the 1st adhesive layer 3 can ensure adhesive force at room temperature, and improves workability | operativity as a result. Can do.

  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 linear alkyl group having 16 or more carbon atoms, (meth) acrylate having an alkyl group having 1 to 6 carbon atoms, polar monomer, etc. Is mentioned.

  Examples of the (meth) acrylate having a linear alkyl group having 16 or more carbon atoms include 16 to 22 carbon atoms such as cetyl (meth) acrylate, stearyl (meth) acrylate, eicosyl (meth) acrylate, and behenyl (meth) acrylate. (Meth) acrylate having a linear alkyl group of, for example, (meth) acrylate having an alkyl group having 1 to 6 carbon atoms such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate Hexyl (meth) acrylate and the like, and examples of polar monomers include ethylenically unsaturated monomers having a carboxyl group such as acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid; 2-hydroxy Ethyl (meth) acrylate, 2-hydroxy Propyl (meth) acrylate, 2-hydroxyhexyl (meth) ethylenically unsaturated monomer having a hydroxyl group such as acrylate and the like, which may be used alone or in combination.

  The first side chain crystalline polymer is a polymer obtained by polymerizing a (meth) acrylate having a linear alkyl group having at least 16 carbon atoms, preferably 18 carbon atoms or more among the above-described monomers. It is good. Each of the monomers described above is, for example, 30 to 100 parts by weight of (meth) acrylate having a linear alkyl group having 16 or more carbon atoms, and 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 in a proportion of 0 to 10 parts by weight.

  Specific examples of the composition of the first side chain crystalline polymer include a copolymer obtained by polymerizing behenyl acrylate, stearyl acrylate, methyl acrylate and acrylic acid. Further, each of the above-described monomers is polymerized at 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. Is preferred.

  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 and the like can be employed. When the solution polymerization method is employed, the above-described monomer may be mixed in 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 6,000 to 11,000. Is more preferable. Thereby, when the tape 1 is peeled from the pedestal, it is possible to suppress the occurrence of adhesive residue. Moreover, 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. The weight average molecular weight is a value obtained by measuring the first side chain crystalline polymer by GPC and converting the obtained measurement value into polystyrene.

  The first side chain crystalline polymer is preferably blended in a proportion of 0.5 to 10 parts by weight with respect to 100 parts by weight of the first pressure-sensitive adhesive in terms of solid content, and 0.5 to 5 parts by weight. It is more preferable that they are blended at a ratio of Thereby, when the 1st side chain crystalline polymer shows fluidity | liquidity at the temperature more than melting | fusing point, the adhesive force of the 1st adhesive layer 3 can fully be 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 pyrolytic and reactive organic foaming agents and inorganic foaming agents.

  Examples of the pyrolytic organic foaming agent include various azo compounds (such as azodicarbonamide), nitroso compounds (such as N, N′-dinitrosopentamethylenetetramine), and hydrazine derivatives [4,4′-oxybis (benzene). Sulfonyl hydrazide) and the like], semicarbazide compound (hydrazodicarbonamide and the like), azide compound, tetrazole compound and the like. Examples of the reactive organic foaming agent include isocyanate compounds.

  Examples of the thermal decomposition type inorganic foaming agent include bicarbonate / carbonate (sodium bicarbonate, etc.), nitrite / hydride, etc. Examples of the reaction type inorganic foaming agent include sodium bicarbonate and the like. The combination with an acid, the combination of hydrogen peroxide and yeast, the combination of zinc powder and an acid, etc. are mentioned.

  Examples of the physical foaming agent include organic physical foaming agents such as aliphatic hydrocarbons such as butane, pentane and hexane, chlorohydrocarbons such as dichloroethane and dichloromethane, and fluorochlorohydrocarbons such as chlorofluorocarbons; air, carbonic acid Examples thereof include inorganic physical foaming agents such as gas and nitrogen gas.

  As another foaming agent, a so-called microballoon foaming agent that is microencapsulated thermally expandable fine particles can be employed. The microballoon foaming agent is obtained by encapsulating a heat-expandable substance made of a solid, liquid, or gas inside a polymer shell made of a thermoplastic or thermosetting resin. In other words, the microballoon foaming agent includes a hollow polymer shell having an average particle size of micro order, and a heat-expandable substance enclosed in the polymer shell. The microballoon foaming agent expands in volume by 40 times or more by heating, and a foam in the form of closed cells is obtained. Therefore, the microballoon foaming agent has a characteristic that the expansion ratio is considerably larger than that of a normal foaming agent. As such a microballoon foaming agent, a commercially available product can be used. For example, “461DU20” manufactured by EXPANCEL is suitable.

  The foaming agent is preferably blended in a proportion of 5 to 30 parts by weight, and in a proportion of 10 to 30 parts by weight, based on 100 parts by weight of the first pressure-sensitive adhesive in terms of solid content. More preferred. Thereby, when a foaming agent expand | swells thru | or foams, the adhesive force of the 1st adhesive layer 3 can fully be reduced.

  The temperature at which the foaming agent expands or foams is usually higher than the melting point of the first side chain crystalline polymer. Further, the temperature at which the foaming agent expands or foams is usually 180 ° C. or less, and it is preferable that the expansion or foaming starts at 90 ° C. and the foaming agent substantially completely foams at 120 ° C.

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

  In order to laminate the first pressure-sensitive adhesive layer 3 containing the first pressure-sensitive adhesive and the first side-chain crystalline polymer described above together with such a foaming agent on one side 21 of the base material 2, for example, first pressure-sensitive What is necessary is just to apply | coat the coating liquid which added the adhesive agent, the 1st side chain crystalline polymer, and the foaming agent to the solvent to the single side | surface 21 of the base material 2 with a coater etc., and to dry. Examples of the coater include a knife coater, a roll coater, a calendar coater, a comma coater, a gravure coater, and a rod coater.

  As thickness of the 1st adhesive layer 3, it is preferable that it is 10-50 micrometers, it is more preferable that it is 10-30 micrometers, and it is further more preferable that it is 15-25 micrometers.

  In addition, various additives, such as a crosslinking agent, a tackifier, a plasticizer, an anti-aging agent, an ultraviolet absorber, can be added to the 1st adhesive layer 3, and a crosslinking agent is illustrated among the illustrated additives. Is preferably added. Examples of the crosslinking agent include isocyanate compounds. The cross-linking agent is preferably added at a rate of 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the first pressure-sensitive adhesive in terms of solid content. More preferably, it is more preferably added at a ratio of 0.1 to 2 parts by weight.

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

(Second adhesive layer)
As for the 2nd adhesive layer 4 laminated | stacked on the other surface 22 of the base material 2 mentioned above, a to-be-adhered body is a to-be-processed object, a 2nd pressure sensitive adhesive and a 2nd side chain crystalline polymer are contained, It is a temperature-sensitive adhesive layer in which the adhesive strength decreases at a temperature equal to or higher than the melting point of the second side chain crystalline polymer.

  The second pressure sensitive adhesive preferably has a weight average molecular weight larger than the weight average molecular weight of the first pressure sensitive adhesive described above. Thereby, since the cohesive force of the 2nd adhesive layer 4 improves rather than the cohesive force of the 1st adhesive layer 3, the retention strength which hold | maintains a to-be-processed object improves, As a result, a to-be-processed object is combined with the tape 1 When peeling from the pedestal, the workpiece can be prevented from falling off 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 the weight of the second pressure-sensitive adhesive is within this numerical range. The average molecular weight is preferably larger than the weight average molecular weight of the first pressure sensitive adhesive. Thereby, the above-described effect can be obtained while suppressing generation 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.
The other configuration of the second pressure-sensitive adhesive is the same as that of the first pressure-sensitive adhesive described above, and a description thereof will be omitted.

  On the other hand, the second side chain crystalline polymer preferably has a melting point of 45 ° C. or higher and lower than 55 ° C., similar to the first side chain crystalline polymer described above. 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 6,000 to 11,000. More preferably. The second side chain crystalline polymer is preferably blended at a ratio of 0.5 to 10 parts by weight with respect to 100 parts by weight of the second pressure-sensitive adhesive in terms of solid content, and 0.5 to 5 parts by weight. It is more preferable that they are blended at a ratio of

The melting point, composition, weight average molecular weight, blending amount, etc. of the second side chain crystalline polymer may be the same as or different from those of the first side chain crystalline polymer described above.
Since the other structure of the second side chain crystalline polymer is the same as that of the first side chain crystalline polymer described above, description thereof is omitted.

  The thickness of the second pressure-sensitive adhesive layer 4 containing the second pressure-sensitive adhesive and the second side chain crystalline polymer is preferably smaller than the thickness of the first pressure-sensitive adhesive layer 3 described above. In other words, the thickness of the first pressure-sensitive adhesive layer 3 is preferably larger than the thickness of the second pressure-sensitive adhesive layer 4. In the present embodiment, the thickness of the first pressure-sensitive adhesive layer 3 is configured to be larger than the thickness of the second pressure-sensitive adhesive layer 4. According to such a configuration, when the workpiece is pressed against the pedestal via the tape 1, the thick first adhesive layer 3 adhered to the pedestal spreads along the surface shape of the pedestal, and the contact area is increased. Since it becomes large, the temporarily fixed state of the workpiece can be stabilized. Further, since the thin second adhesive layer 4 to be adhered to the workpiece is difficult to protrude from the outer peripheral portion of the tape 1, the workpiece is contaminated by the excess second adhesive layer 4 protruding. Can be suppressed.

  As thickness of the 2nd adhesive layer 4, it is preferable that it is 5-40 micrometers, It is more preferable that it is 5-20 micrometers, It is further more preferable that it is 5-15 micrometers, Within this numerical range, 1st adhesion It is preferable to make the thickness of the agent layer 3 larger than the thickness of the second pressure-sensitive adhesive layer 4.

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

As a particularly preferred formulation 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, and the second pressure-sensitive adhesive: second side chain. The ratio which becomes crystalline polymer: crosslinking agent = 100: 1-5: 0.4-0.6 is mentioned.
Since the other structure of the 2nd adhesive layer 4 is the same as that of the 1st adhesive layer 3 mentioned above, description is abbreviate | omitted.

  The tape 1 of this embodiment described above further includes the first separator 5 laminated on the surface 31 of the first pressure-sensitive adhesive layer 3 and the second separator 6 laminated on the surface 41 of the second pressure-sensitive adhesive layer 4. I have. Thereby, the surface 31 of the 1st adhesive layer 3 and the surface 41 of the 2nd adhesive layer 4 can each be protected.

  Examples of the first separator 5 and the second separator 6 include a film made of polyethylene, polyethylene terephthalate or the like, and a release agent such as silicone or fluorine applied to the surface of the film. Moreover, as thickness of each of the 1st separator 5 and the 2nd separator 6, it is preferable that it is 10-110 micrometers.

  The first separator 5 and the second separator 6 may have the same composition, thickness, or the like, or may be different. In the present embodiment, the first separator 5 is obtained by applying silicone to the surface of a polyethylene film, and the second separator 6 is obtained by applying silicone to the surface of a polyethylene terephthalate film. In the present embodiment, the thickness of the first separator 5 is larger than the thickness of the second separator 6.

  In the tape 1 of this embodiment, the 180 ° peel strength at 23 ° C. of the first pressure-sensitive adhesive layer 3 is preferably 2 to 16 N / 25 mm, and more preferably 6 to 12 N / 25 mm. Thereby, the fixing force with respect to a base can be obtained. The 180 ° peel strength of the first pressure-sensitive adhesive layer 3 is a value obtained by measuring the 180 ° peel strength for a polyethylene terephthalate film at an ambient temperature of 23 ° C. according to JIS Z0237.

  Moreover, as for the tape 1 of this embodiment, it is preferable that the 180 degree peeling strength in 23 degreeC of the 2nd adhesive layer 4 is 0.5-10N / 25mm, and it is more preferable that it is 1-3.5N / 25mm. preferable. Thereby, the fixing force with respect to workpieces, such as sapphire glass, can be obtained. The 180 ° peel strength of the second pressure-sensitive adhesive layer 4 is a value obtained by measuring the 180 ° peel strength with respect to sapphire glass at an ambient temperature of 23 ° C. according to JIS Z0237.

<Temporary fixing method of workpiece>
Next, a method for temporarily fixing a workpiece according to an embodiment of the present invention will be described in detail with reference to FIG.

  In this embodiment, first, as shown in FIG. 2B, the workpiece 200 is temporarily fixed on the pedestal 100 via the tape 1 as shown in FIG. The workpiece 200 is peeled from the pedestal 100 together with the tape 1.

  Specifically, as the workpiece 200, a desired one can be adopted and is not particularly limited, but sapphire glass or the like that is a material of the LED substrate is suitable. The workpiece 200 of this embodiment is sapphire glass. Moreover, as the base 100, the thing made from a ceramic is mentioned, for example.

  As shown in FIG. 2 (a), the workpiece 200 has a tape 1 in a state where the first adhesive layer 3 is attached to the base 100 and the second adhesive layer 4 is attached to the workpiece 200, respectively. And temporarily fixed on the pedestal 100. Thereby, even if the workpiece 200 is polished, it is possible to prevent the unevenness derived from the foaming agent from being transferred to the workpiece 200 and reducing the yield.

  Then, the tape 1 is heated to a temperature equal to or higher than the melting point of the first side chain crystalline polymer described above and the foaming agent expands or foams. As a result, 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 adhesive layer 3 can be sufficiently reduced. As a result, as shown in FIG. 2 (b), the workpiece 200 can be smoothly peeled off from the pedestal 100 together with the tape 1 in the direction of arrow A, and therefore an external force is applied during peeling. It is possible to prevent the yield from being lowered due to damage to the 200. Examples of the heating means for heating the tape 1 include a heater.

  In addition, with the fall of the adhesive force of the 1st adhesive layer 3, also in the 2nd adhesive layer 4, it becomes the temperature more than melting | fusing point of the 2nd side chain crystalline polymer which contains normally, and adhesive force becomes. However, since the adhesive force does not completely disappear, the workpiece 200 can be continuously fixed by the second adhesive layer 4 unless a large external force is applied.

  After the workpiece 200 is peeled from the pedestal 100 together with the tape 1, 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 pressure-sensitive adhesive layer 4, and FIG. As shown in (c), the workpiece 200 is peeled from the tape 1 in the direction of arrow B. At this time, according to the tape 1, it is difficult for adhesive residue to occur on the workpiece 200, so that the cleaning process can be simplified or omitted.

  EXAMPLES Hereinafter, although a synthesis example and an Example are given and this invention is demonstrated in detail, this invention is not limited only to the following synthesis examples and Examples. In the following description, “part” means part by weight.

(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 0.3 part of perbutyl ND (manufactured by NOF Corporation) as a polymerization initiator in 200 parts of toluene, respectively. In addition, the monomers were polymerized by stirring at 60 ° C. for 5 hours. 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 is changed to 60 ° C. to 55 ° C., perbutyl ND (manufactured by NOF Corporation) is changed to 0.2 part instead of 0.3 part, and the solvent is changed to toluene and ethyl acetate: heptane = 7: 3 Except for the weight ratio, 2-ethylhexyl acrylate, methyl acrylate and 2-hydroxyethyl acrylate were polymerized in the same manner as in Synthesis Example 1. The weight average molecular weight of the obtained copolymer was 450,000.

(Synthesis Example 3: First and second side chain crystalline polymers)
40 parts of behenyl acrylate, 35 parts of stearyl acrylate, 20 parts of methyl acrylate, 5 parts of acrylic acid, 6 parts of dodecyl mercaptan as a chain transfer agent, and 1 perhexyl PV (manufactured by NOF Corporation) as a polymerization initiator. These monomers were polymerized at a ratio of 0 part in 100 parts of toluene and stirred at 80 ° C. for 5 hours. The obtained copolymer had a weight average molecular weight of 8,000 and a melting point of 50 ° C.

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

<Production of double-sided adhesive tape>
First, the copolymers, foaming agents and crosslinking agents obtained in Synthesis Examples 1 to 3 were mixed in the combinations shown in Table 2 to obtain a mixture. In Table 2, the ratio indicates a weight ratio in terms of solid content.

The relationships between the copolymers 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 used foaming agent and cross-linking agent are as follows.
Foaming agent: Microballoon foaming agent “461DU20” manufactured by EXPANCEL having an average particle diameter of 6 to 9 μm and a foaming start temperature of 90 ° C. or higher.
Crosslinking agent: Isocyanate compound “Coronate L-45E” manufactured by Nippon Polyurethane Industry Co., Ltd.

Next, the obtained mixture was adjusted with ethyl acetate so that the solid content would be 30% by weight to obtain a coating solution. And the obtained coating liquid was apply | coated to the 100-micrometer-thick film-form base material which consists of a polyethylene terephthalate, it was made to dry, and the double-sided adhesive tape was obtained. Drying was performed for every 1st, 2nd adhesive layer using the heater. Drying conditions are as follows.
First pressure-sensitive adhesive layer: 80 ° C. × 10 minutes Second pressure-sensitive adhesive layer: 100 ° C. × 10 minutes

In the obtained double-sided pressure-sensitive adhesive tape, the thicknesses of the first and second pressure-sensitive adhesive layers are as follows.
First adhesive layer thickness: 20 μm
Second adhesive layer thickness: 10 μm

<Evaluation>
The obtained double-sided pressure-sensitive adhesive tape was evaluated for peel strength, foam peelability, adhesive residue and abrasiveness. Each evaluation method is shown below, and the results are shown in Table 2.

(Peel strength)
The 180 ° peel strength at an ambient temperature of 23 ° C. of the first and second pressure-sensitive adhesive layers was evaluated. First, at an ambient temperature of 23 ° C., the first pressure-sensitive adhesive layer was placed on the upper side, and the second pressure-sensitive adhesive layer was fixed to the stainless steel plate via a commercially available double-sided tape. Next, a polyethylene terephthalate film having a thickness of 25 μm was attached to the first pressure-sensitive adhesive layer. And the polyethylene terephthalate film was peeled 180 degree | times from the 1st adhesive layer at a speed | rate of 300 mm / min using the load cell. 180 degree peeling strength at this time was measured based on JIS Z0237, and 180 degree peeling strength in 23 degreeC atmospheric temperature of a 1st adhesive layer was evaluated. The 180 ° peel strength at 23 ° C. of the second pressure-sensitive adhesive layer is the same as that except that the double-sided pressure-sensitive adhesive tape was attached to sapphire glass via the second pressure-sensitive adhesive layer and the double-sided pressure-sensitive adhesive tape was peeled 180 ° from the sapphire glass. Evaluation was performed in the same manner as the pressure-sensitive adhesive layer. Each evaluation result is shown in the column of “peel strength” in Table 2.

(Foaming peelability)
First, a double-sided pressure-sensitive adhesive tape was attached to a ceramic plate via a first pressure-sensitive adhesive layer at an ambient temperature of 23 ° C. Next, 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 foaming agent expands or foams. At this time, it was visually observed whether or not the double-sided pressure-sensitive adhesive tape was peeled off from the ceramic plate only by its own weight. The evaluation criteria were set as follows.
○: Peeled within 120 seconds.
(Triangle | delta): It peeled within 120 second over 120 second.
X: It did not peel within 300 seconds.

(Adhesive residue)
First, each surface of the double-sided pressure-sensitive adhesive tape was attached to sapphire glass at an ambient temperature of 23 ° C. Next, the double-sided pressure-sensitive adhesive tape was peeled off at an ambient temperature of 130 ° C. for the first pressure-sensitive adhesive layer, and the double-sided pressure-sensitive adhesive tape was peeled off at an atmospheric temperature of 60 ° C. for the second pressure-sensitive adhesive layer. And the adhesive residue (residue) was evaluated by visually observing the surface of the sapphire glass after peeling. The evaluation criteria were set as follows.
○: Some glue residue (residue) was observed in the sapphire glass, but it was in a range where there was no problem in actual use.
Δ: Adhesive residue (residue) was observed on the sapphire glass.
X: A large amount of adhesive residue (residue) was observed in the sapphire glass.

(Abrasiveness)
First, at an atmospheric temperature of 23 ° C., a double-sided pressure-sensitive adhesive tape was attached to a surface plate of a polishing machine via the first pressure-sensitive adhesive layer. Next, a plate-like workpiece made of sapphire glass having a thickness of 635 μm was attached to the double-sided pressure-sensitive adhesive tape via the second pressure-sensitive adhesive layer. The polishing conditions were set as follows.
Polishing machine: Surface plate size 36 inches Polishing pressure: 170 kgf / axis Surface plate rotation speed: 45 rpm
Slurry: Colloidal silica Abrasive cloth: Non-woven fabric type Atmospheric temperature: 23 ° C
Exothermic temperature range during polishing: 23-45 ° C

The workpiece was polished to a thickness of 620 μm under the above polishing conditions. At this time, the abrasiveness was evaluated by visually observing whether or not the first and second pressure-sensitive adhesive layers were displaced. The visual observation was performed during or after polishing. Moreover, the evaluation criteria were set as follows.
○: No deviation occurred in any of the first and second pressure-sensitive adhesive layers.
X: Deviation occurred in at least one of the first and second pressure-sensitive adhesive layers.

Claims (10)

A film-like substrate;
A first pressure-sensitive adhesive layer laminated on one side of the base material and adhered to a pedestal;
A second pressure-sensitive adhesive layer that is laminated on the other surface of the base material and adheres 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 a second pressure-sensitive adhesive and a second side chain crystalline polymer, and has a pressure-sensitive adhesive strength that decreases at a temperature equal to or higher than the melting point of the second side chain crystalline polymer. Double-sided adhesive tape.   The double-sided pressure-sensitive adhesive tape for temporary fixing according to claim 1, wherein a weight average molecular weight of the second pressure-sensitive adhesive is larger than a weight average molecular weight of the first pressure-sensitive adhesive.   The double-sided pressure-sensitive adhesive tape for temporary fixing according to claim 1 or 2, wherein a thickness of the first pressure-sensitive adhesive layer is larger than a thickness of the second pressure-sensitive adhesive layer.   The said 1st pressure sensitive adhesive and the said 2nd pressure sensitive adhesive are the copolymers obtained by polymerizing 2-ethylhexyl acrylate, methyl acrylate, and 2-hydroxyethyl acrylate, Any of Claims 1-3 The double-sided pressure-sensitive adhesive tape for temporary fixation according to crab.   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. The double-sided adhesive tape for temporary fixing in any one of 1-4.   The said 1st side chain crystalline polymer and the said 2nd side chain crystalline polymer are the copolymers obtained by polymerizing behenyl acrylate, stearyl acrylate, methyl acrylate, and acrylic acid, Any one of Claims 1-5 The double-sided pressure-sensitive adhesive tape for temporary fixation according to crab.   The temporary melting point according to any one of claims 1 to 6, wherein both of the melting point of the first side chain crystalline polymer and the melting point of the second side chain crystalline polymer are 45 ° C or higher and lower than 55 ° C. Double-sided adhesive tape.   The said foaming agent is a microballoon foaming agent provided with the hollow polymer shell which has an average particle diameter of micro order, and the heat-expandable substance enclosed with the inside of the said polymer shell. The double-sided pressure-sensitive adhesive tape for temporary fixing according to any one of the above. 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 double-sided pressure-sensitive adhesive tape for temporary fixing according to any one of claims 1 to 8, wherein the second pressure-sensitive adhesive layer has a 180 ° peel strength with respect to sapphire glass at an ambient temperature of 23 ° C of 0.5 to 10 N / 25 mm.   The temporary fixing according to any one of claims 1 to 9, 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. Double-sided adhesive tape.

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