JP2013103955A - Method of producing heat transfer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing a heat transfer sheet excellent in thermal conductivity.SOLUTION: A method of producing a heat transfer sheet includes: a magnetic field-applying step of applying an alternating magnetic field to a sheet-molding material that contains a curing composition containing a curing resin and particles each containing a magnetic body; and a curing step of curing the sheet-molding material to which the alternating magnetic field is applied through the magnetic field-applying step.

Description

  The present invention relates to a method for manufacturing a heat transfer sheet. More specifically, the present invention relates to a method for manufacturing a heat transfer sheet provided to radiate heat generated from an electronic component in an electronic device or a light source in a lighting device.

  In an electronic device including an electronic component such as a CPU (Central Processing Unit), heat generated from the electronic component such as a CPU is radiated to the outside of the electronic device during use.

As a heat dissipation means in an electronic device, a heat transfer sheet in which particles made of a material having high thermal conductivity (such as a metal or a ceramic material) are contained in a sheet base made of a polymer material, an electronic component and a heat sink ( There is a means for conducting heat generated in the electronic component to the heat radiating plate through the heat transfer sheet by disposing it between the heat sink and the heat sink.
As such a heat transfer sheet, a heat transfer sheet containing composite particles in which the surface of the base particle is coated with fine particles and containing the composite particles in the thickness direction in the sheet base is provided. It has been proposed (see, for example, Patent Document 1).

  In addition, as a heat radiating means in an electronic device, a heat radiating member for an electronic device comprising a sintered powder of a mixed powder containing a composite particle powder in which the surface of silicon carbide particles is coated with aluminum fine particles and a matrix forming powder made of aluminum particles Has been proposed (see, for example, Patent Document 2).

On the other hand, various gasket forming materials have been developed in the technical field of gaskets for electronic components.
For example, for the purpose of providing a gasket having low solubility of siloxane present in the air, a hydrogenated conjugated diene-aromatic vinyl copolymer containing a photocurable functional group, a (meth) acrylate monomer, and a photopolymerization initiator are used. The photocurable composition to contain is proposed (for example, refer patent document 3).
Further, for the purpose of providing a gasket capable of improving the reworkability of the cover plate and the base plate in the hard disk device, an energy ray-curable urethane liquid oligomer having a polymerizable unsaturated group, and a glass transition temperature (Tg) of −70. Gasket forming materials containing a monofunctional (meth) acrylate monomer having a temperature of -20 ° C have been proposed (see, for example, Patent Document 4).

JP 2011-35221 A JP 2009-242899 A JP 2008-291127 A JP 2009-43295 A

As electronic devices become denser and thinner, the effects of heat generated from electronic components have become more serious than ever, and higher performance and higher density of electronic devices have increased heat generation. Therefore, there is a demand for a heat transfer sheet that can transfer heat of electronic components with higher efficiency.
Furthermore, with the increase in density, size, and performance of electronic devices, the heat transfer sheet itself is required to have performance for protecting the electronic devices from the environment. And in many cases, insulation is required for the heat transfer sheet.

  The present invention has been made under the above circumstances. Under the circumstances described above, an object of the present invention is to provide a manufacturing method for manufacturing a heat transfer sheet having excellent thermal conductivity.

Specific means for solving the above-described problems are as follows.
<1> A magnetic field application step of applying an alternating magnetic field to a sheet molding material containing a curable composition containing a curable resin and particles containing a magnetic material, and the sheet molding in which an alternating magnetic field is applied by the magnetic field application step A method for producing a heat transfer sheet, comprising: a curing step for curing the material.
<2> The method for producing a heat transfer sheet according to <1>, wherein the magnetic body is a soft magnetic body.
<3> The heat transfer sheet according to <1> or <2>, wherein the particles are composite particles in which at least a part of the surface of the base particles is coated with fine particles having a particle diameter smaller than the base particles. Production method.
<4> The method for producing a heat transfer sheet according to any one of <1> to <3>, wherein the curable composition further includes a (meth) acrylate monomer and a polymerization initiator.
<5> The curable resin includes at least one selected from a hydrogenated conjugated diene-aromatic vinyl copolymer having a polymerizable unsaturated group and a urethane liquid oligomer having a polymerizable unsaturated group. The manufacturing method of the heat-transfer sheet | seat of any one of>-<4>.
<6> The method for producing a heat transfer sheet according to <5>, wherein the polymerizable unsaturated group of the hydrogenated conjugated diene-aromatic vinyl copolymer is a (meth) acryloyl group.
<7> The (meth) acrylate monomer is an alkyl group having 8 to 18 carbon atoms, isobornyl group, cyclohexyl group, dicyclopentanyl group, dicyclopentenyl group, dicyclopentanyloxyethyl group, dicyclopentenyloxyethyl. The manufacturing method of the heat-transfer sheet | seat of any one of said <4>-<6> which has group, nonylphenoxy polyethyleneglycol residue, or nonylphenoxypolypropyleneglycol residue.
<8> The (meth) acrylate monomer according to any one of <4> to <7>, including a monofunctional (meth) acrylate monomer having a glass transition temperature of −70 ° C. or higher and 20 ° C. or lower. Manufacturing method of heat transfer sheet.
<9> Particles containing a magnetic substance in a sheet substrate made of a curable composition containing a curable resin, produced by the method for producing a heat transfer sheet according to any one of <1> to <8>. A heat transfer sheet that is contained in an oriented state.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method which manufactures the heat-transfer sheet | seat excellent in heat conductivity is provided.

It is sectional drawing which shows one structural example of the heat-transfer sheet | seat manufactured by the manufacturing method of this invention. It is sectional drawing which shows the other structural example of the heat-transfer sheet | seat manufactured by the manufacturing method of this invention. It is sectional drawing which shows an example of the formwork used for the manufacturing method of this invention. It is sectional drawing which shows the state in which the sheet molding material layer was formed in the mold shown in FIG. It is sectional drawing which shows an example of the apparatus used for the manufacturing method of this invention. It is sectional drawing which shows the state by which the sheet forming material layer was hardened | cured with the apparatus shown in FIG. It is sectional drawing which shows an example of the formwork used in order to manufacture the heat-transfer sheet | seat of the structure shown in FIG. It is sectional drawing which shows the outline of the apparatus used for the Example of this invention.

Hereinafter, embodiments of the present invention will be sequentially described. In addition, these description and Examples illustrate this invention, and do not restrict | limit the scope of the present invention.
In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended action of the process is achieved even when the process is performed simultaneously with another process. It is.
In the present specification, a numerical range indicated using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
In this specification, a (meth) acrylate monomer refers to an acrylate monomer and / or a methacrylate monomer, a (meth) acrylate refers to an acrylate and / or a methacrylate, a (meth) acryloyl group refers to an acryloyl group and / or Or a methacryloyl group.

≪Method for manufacturing heat transfer sheet≫
The manufacturing method of the heat-transfer sheet | seat of this invention includes the magnetic field application process which applies an alternating magnetic field to a sheet molding material, and the hardening process which hardens the said sheet molding material to which the alternating magnetic field was applied by the said magnetic field application process.
The sheet molding material is a mixture of a curable composition containing a curable resin and particles containing a magnetic material (hereinafter also referred to as “magnetic particles”), and at least the curable composition and the magnetic particles. Containing.
By the manufacturing method having such a configuration, a heat transfer sheet can be obtained in which the magnetic particles are contained in an oriented state in a sheet substrate formed by curing the curable composition.
Since the heat transfer sheet manufactured by the above manufacturing method is contained in a state where the magnetic particles are oriented in the sheet base, a heat transfer path extending in the orientation direction is formed by the chain of the magnetic particles, and the magnetic High thermal conductivity is obtained in the direction of grain orientation.

  Although the manufacturing method of the heat-transfer sheet | seat of this invention contains the said magnetic field application process and the said hardening process at least, you may include another process as needed. It is preferable that the manufacturing method includes a sheet forming step of forming the sheet forming material into a sheet shape. Moreover, the said manufacturing method may provide the post-baking process which heat-processes after hardening of the said sheet forming material in order to remove the volatile component contained in the said sheet forming material.

<Magnetic field application process>
The magnetic field applying step is a step of applying an alternating magnetic field to a sheet molding material containing a curable composition containing a curable resin and particles containing a magnetic material. By this process, the magnetic particles dispersed in the sheet molding material move in the sheet molding material and are oriented in the direction of the applied alternating magnetic field.

Specific processing conditions such as the intensity and frequency of the alternating magnetic field to be applied and the time for applying the alternating magnetic field are appropriately selected in consideration of the time required to move the magnetic particles.
The strength of the alternating magnetic field to be applied is selected depending on the particle diameter of the magnetic particles, the viscosity of the curable composition, and the like, but is preferably 20 millitesla or more.
The frequency of the alternating magnetic field to be applied may be 50 Hz or 60 Hz, for example, or other frequencies may be selected.

  The direction in which the alternating magnetic field is applied is not particularly limited, and may be a direction in which the magnetic particles are to be oriented. For example, when it is desired to orient the magnetic particles in the thickness direction of the heat transfer sheet, the sheet molding material may be molded into a sheet shape and a magnetic field may be applied in the thickness direction.

<Curing process>
The curing step is a step of curing the sheet molding material to which an alternating magnetic field is applied in the magnetic field application step. By the curing step, the curable composition is cured to become a sheet substrate, and the magnetic particles are contained in the sheet substrate in a state in which the orientation direction aligned by the magnetic field application step is maintained.
The curing step may be performed while applying an alternating magnetic field to the sheet molding material, or may be performed after the application of the alternating magnetic field is stopped.
The method of the curing treatment is appropriately selected depending on the curable composition to be used, but is usually performed by irradiation with energy rays and can also be performed by heating.

The energy rays used for the curing treatment include ultraviolet rays, electron beams, α rays, β rays, and γ rays, and among these, ultraviolet rays are particularly preferable in the present invention. Ultraviolet rays are simple and easy to use, and have a high degree of curing. The atmosphere for irradiation with ultraviolet rays is preferably an inert gas atmosphere such as nitrogen gas or carbon dioxide gas, or an atmosphere with a reduced oxygen concentration, but can be sufficiently cured even in a normal air atmosphere.
Specific processing conditions for the curing treatment using energy rays are appropriately selected in consideration of the type of material contained in the curable composition.

  When the curing treatment is performed by heating, the heating conditions are not particularly limited and are appropriately selected in consideration of the type of material contained in the curable composition. For example, the sheet molding material layer can be cured by holding at a temperature of 50 ° C. to 200 ° C. for 10 minutes to 3 hours.

<Sheet forming process>
The method for producing a heat transfer sheet of the present invention preferably includes a sheet forming step of forming the sheet forming material into a sheet shape, and an alternating magnetic field is applied to the sheet forming material formed into a sheet shape.
The method for forming the sheet is not particularly limited. For example, a method of applying the sheet molding material on a sheet made of a resin such as polyethylene terephthalate (PET), or a method of extruding the sheet molding material may be employed.

  Hereinafter, the present invention will be described with reference to specific examples of the method for manufacturing the heat transfer sheet of the present invention and specific examples of the heat transfer sheet manufactured by the above manufacturing method. It is not limited.

FIG. 1 is a cross-sectional view showing one configuration example of the heat transfer sheet. The heat transfer sheet 10 shown in FIG. 1 contains magnetic particles 12 in a sheet base 11 having flat surfaces. The sheet substrate 11 is formed by curing a curable composition containing a curable resin. A plurality of magnetic particles 12 are oriented in the thickness direction of the sheet substrate 11, and a heat transfer path is formed by a chain of the plurality of magnetic particles 12. In the illustrated heat transfer sheet 10, the magnetic particles 12 are contained in a state in which they are aligned so as to be aligned in the thickness direction of the sheet base 11 uniformly over the entire surface direction of the sheet base 11.
FIG. 2 is a cross-sectional view showing another configuration example of the heat transfer sheet. A heat transfer sheet 30 shown in FIG. 2 includes a high density portion 32 in which magnetic particles are densely packed in a state in which the magnetic particles are oriented in the thickness direction, and a low density portion 33 in which no or almost no magnetic particles are present. It consists of.

In the method for producing a heat transfer sheet of the present invention, a method using a sheet for forming a sheet molding material layer can be applied as follows.
First, the curable composition and the magnetic particles are mixed, and a sheet molding material is prepared by stirring or the like. The sheet molding material preferably has fluidity from the viewpoint of facilitating sheet molding. The content of the magnetic particles in the sheet molding material may be selected in consideration of the fluidity and curing efficiency of the sheet molding material, the thermal conductivity imparted to the sheet, and the like.

Next, the above-mentioned sheet molding material is applied to one or both surfaces of two sheet molding material layer forming sheets (hereinafter also referred to as “material layer forming sheets”) prepared in advance, and these sheets are used. Are overlapped to form a sheet molding material layer between two sheets. Here, as the material layer forming sheet, for example, a sheet made of a resin such as polyethylene terephthalate (PET) can be used.
Further, from the viewpoint of handleability, a glass plate or the like may be laminated on the outside of the material layer forming sheet as a support. Further, when a sheet molding material is applied to the material layer forming sheet, the thickness can be easily determined by using a resin spacer.

Next, a magnetic field application process for applying an alternating magnetic field in a desired direction (for example, the thickness direction) is performed on the laminate in which the sheet molding material layer is formed between the two material layer forming sheets. Use a generator. Then, while performing the magnetic field application process or after stopping the magnetic field application process, a curing process (energy ray irradiation or heating) is performed. Thereafter, the material layer forming sheet is peeled off from the laminate, and preferably a heat treatment (post-baking step) is performed.
As a result, in the sheet molding material layer, the magnetic particles dispersed therein are aligned in a desired direction (for example, the thickness direction), and in this state, the sheet molding material layer is cured by a curing process. A sheet base is formed, and thus a heat transfer sheet having a structure as shown in FIG. 1 is manufactured.

The AC magnetic field generator used for the magnetic field application process includes at least one electromagnet, and generates an AC magnetic field by supplying an AC current from an AC power source to the electromagnet.
In the magnetic field application process, the arrangement position of the electromagnet and the sheet molding material layer provided in the AC magnetic field generator is selected so that the magnetic field is applied to the sheet molding material layer in a desired direction. At this time, in order to align the direction of the magnetic field applied to the sheet molding material layer, the electromagnet and the sheet molding material layer are arranged so that the sheet molding material layer is arranged in a portion where the lines of magnetic force are arranged in parallel in the magnetic field. It is preferable to select the arrangement position.
The frequency of the AC current supplied to the AC magnetic field generator is not particularly limited, and may be 50 Hz or 60 Hz, or any other frequency may be selected.
The strength of the alternating magnetic field to be applied is selected according to the particle diameter of the magnetic particles, the viscosity of the curable composition, the thickness of the sheet molding material layer, and the like, but is preferably 20 millitesla or more.

As an energy ray used for said hardening process, an ultraviolet-ray is preferable. Examples of the ultraviolet light source include a xenon lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, a metal halide lamp, and a microwave excimer lamp. The irradiation temperature of the ultraviolet light can be usually 10 ° C to 200 ° C. Moreover, when providing a post-baking process after hardening, 100 to 160 degreeC baking temperature is preferable.
When performing said hardening process by a heating, a sheet molding material layer can be hardened by hold | maintaining for 10 minutes-3 hours, for example at the temperature of 50 to 200 degreeC. In this case, the post-baking step is performed at a heating temperature higher than the heating temperature during the curing process.

  In addition, a method using a formwork as shown in FIG. 3 can be applied. FIG. 3 is a cross-sectional view showing an example of a mold used in the method for producing a heat transfer sheet of the present invention. 3 is configured such that an upper mold 21 and a lower mold 22 that is paired with the upper mold 21 are arranged to face each other with a frame-shaped spacer 23 interposed therebetween. The material composition of the upper mold | type 21 and the lower mold | type 22 is not ask | required.

A heat transfer sheet is manufactured as follows using a formwork as shown in FIG.
First, a fluid sheet molding material is prepared by dispersing the magnetic particles in the curable composition. Then, this sheet molding material is applied to the surface of one or both of the upper mold 21 and the lower mold 22. Next, the upper mold 21 and the lower mold 22 are overlapped to form the sheet molding material layer 11A as shown in FIG.

  Next, as shown in FIG. 5, the sheet molding material layer 11 </ b> A is placed in the AC magnetic field generator 25 together with the mold 20. The AC magnetic field generator 25 includes a pair of electromagnets 25A and 25B, and generates an AC magnetic field when an AC current is supplied from an AC power supply. By operating the AC magnetic field generator 25, the AC magnetic field MF is applied to the sheet molding material layer 11A in the thickness direction. As a result, in the sheet molding material layer 11A, the magnetic particles 12 dispersed in the sheet molding material layer 11A are aligned in the thickness direction as shown in FIG. In this state, the sheet base material 11 is formed by curing the sheet molding material layer 11A, whereby the heat transfer sheet having the configuration shown in FIG. 1 is manufactured.

The heat transfer sheet 30 as shown in FIG. 2 can be manufactured using, for example, a mold shown in FIG.
FIG. 7 is a cross-sectional view showing an example of a mold used in the method for producing a heat transfer sheet of the present invention. The mold frame of FIG. 7 is configured by arranging an upper mold 40 and a lower mold 45 that is paired with the upper mold 40 so as to face each other with a frame-shaped spacer 44 therebetween.
In the upper mold 40, a ferromagnetic portion 42 is formed on the lower surface of the ferromagnetic substrate 41 according to a pattern opposite to the high-density portion 32 of the heat transfer sheet 30 shown in FIG. A non-magnetic part 43 is formed at a location. The ferromagnetic portion 42 and the non-magnetic portion 43 have substantially the same thickness, and the lower surface of the upper mold 40, that is, the molding surface is a flat surface.
On the other hand, the lower mold 45 has a ferromagnetic portion 47 formed on the upper surface of the ferromagnetic substrate 46 in accordance with a pattern opposite to the high-density portion 32 of the heat transfer sheet 30 shown in FIG. A non-magnetic portion 48 is formed at a place other than. The ferromagnetic portion 42 and the non-magnetic portion 43 have substantially the same thickness, and the lower surface of the upper mold 40, that is, the molding surface is a flat surface.
As a material constituting the ferromagnetic substrates 41 and 46 and the ferromagnetic portions 42 and 47, iron, nickel, cobalt, or an alloy thereof can be used. Moreover, as a material which comprises the nonmagnetic substance parts 43 and 48, heat resistant resins, such as nonmagnetic metals, such as copper, a polyimide, etc. can be used.

  By using such a formwork and operating an AC magnetic field generator (not shown), the portion located between the ferromagnetic portion 42 in the upper die 40 and the ferromagnetic portion 47 in the lower die 45 is large. An alternating magnetic field having strength is applied. As a result, the magnetic particles dispersed in the sheet molding material layer gather in a portion located between the ferromagnetic portion 42 in the upper mold 40 and the ferromagnetic portion 47 in the lower mold 45, and the thickness is increased. Orient to align in the vertical direction. In this state, the sheet base material 31 is formed by curing the sheet molding material layer, whereby the heat transfer sheet 30 having the configuration shown in FIG. 2 is manufactured.

Hereinafter, the curable composition and the magnetic particles will be described while explaining the heat transfer sheet produced by the production method of the present invention.
≪Heat transfer sheet≫
The heat transfer sheet manufactured by the manufacturing method of the present invention is a heat transfer sheet that is contained in a state in which particles including a magnetic substance are oriented in a sheet substrate made of a curable composition including a curable resin.
Since the heat transfer sheet is contained in a state in which the magnetic particles are oriented in the sheet base, a heat transfer path extending in the orientation direction is formed by the chain of the magnetic particles, and high heat is applied in the orientation direction of the magnetic particles. Conductivity is obtained.

  The heat transfer sheet is used, for example, in a state of being sandwiched between a heating element and a heat receiving body, or in a state of being in contact with the heating element. Specifically, electronic components such as memory modules such as CPU and RIMM (Rambus Inline Memory Module); lighting devices such as lamps, incandescent lamps and fluorescent lamps; LED (Light Emitting Diode) elements and organic EL (Electro Luminescence) elements It is useful as a heat transfer sheet for dissipating heat generated in a device having a light source. In particular, when used in LED elements and organic EL elements, it can be used as a heat sink in addition to being used as a member for conducting heat of a heating element (LED element or organic EL element) to a heat radiating plate (heat sink).

  The heat transfer sheet contains magnetic particles oriented in a sheet base. There is no limitation on the orientation direction of the magnetic particles in the sheet substrate, and the magnetic particles may be oriented in a desired direction. If the heat transfer sheet is used in a state of being sandwiched between a heating element and a heat receiving body, it is preferable that the magnetic particles are oriented in the direction of a line connecting the heating element and the heat receiving body. If the heat transfer sheet is used in a state exposed to the outside air while being in contact with the heating element, it is preferable that the magnetic particles are oriented in a linear direction from the heating element to the outside air. In any use state, the magnetic particles may be oriented, for example, in the thickness direction of the sheet substrate.

  A heat transfer sheet as shown in FIG. 1, that is, a heat transfer sheet having a configuration in which magnetic particles are contained in an aligned state in the thickness direction of the sheet substrate over the entire surface direction of the sheet substrate, It is preferable that the sheet base contains 5 to 50% of magnetic particles in volume fraction. When the volume fraction is 5% or more, it is possible to obtain a heat transfer sheet having low heat resistance in the heat transfer path formed in the thickness direction of the sheet substrate and high heat conductivity. On the other hand, when the volume fraction is 50% or less, the flexibility of the sheet is high. For this reason, it is easy to deform | transform following the surface shape of a heat generating body or a heat receiving body, and it is excellent in sealing performance. The volume fraction is more preferably 7 to 40%, still more preferably 10 to 30%.

  A heat transfer sheet as shown in FIG. 2, that is, a high density portion in which magnetic particles are densely packed in a state of being oriented in the thickness direction in the sheet substrate, and a low density portion in which no or almost no magnetic particles are present. In the heat transfer sheet having the structure, the content ratio of the magnetic particles in the high density portion 32 is preferably 5 to 60%, more preferably 7 to 50% in terms of volume fraction. When the volume fraction is 5% or more, the thermal resistance in the heat transfer path formed in the thickness direction of the sheet substrate is sufficiently small. On the other hand, when the volume fraction is 60% or less, the flexibility of the sheet is high, and the sheet tends to deform following the surface shape of the heating element or the heat receiving body, and thus the sealing performance is excellent.

[Sheet substrate]
The sheet substrate is formed by curing a curable composition containing a curable resin.
The thickness of the sheet substrate is not particularly limited, but is preferably 0.3 mm to 5 mm. More preferably, it is 0.5 mm-3 mm, More preferably, it is 0.7 mm-2 mm. When the thickness of the sheet base is 0.3 mm or more, both the heat generating body and the heat receiving body are easily adhered to the heat transfer sheet when used in a state where the pressure is narrowed between the heat generating body and the heat receiving body. On the other hand, if the thickness of the sheet substrate is 5 mm or less, the heat transfer sheet formed when the magnetic particles are oriented in the thickness direction of the sheet substrate has a small heat resistance and a higher heat conductivity. Can be obtained.

  The sheet substrate is preferably flat on both sides. Specifically, the surface roughness of the front and back surfaces of the sheet substrate is preferably an arithmetic average roughness (Ra) of 50 μm or less, particularly preferably 5 μm or less. When the arithmetic average roughness (Ra) of the sheet substrate is 50 μm or less, when used in a state where the pressure is reduced between the heating element and the heat receiving body, when the pressure is reduced by the heating element and the heat receiving body, A gap is not easily formed between the heat generating body and the heat transfer sheet or between the heat transfer sheet and the heat receiving body, and the heat transfer sheet is easily adhered to each of the heat generating body and the heat receiving body.

[Curable composition]
The sheet substrate is formed by curing a curable composition containing at least one curable resin. From the viewpoint of improving curability, the curable composition preferably further contains at least one (meth) acrylate monomer and at least one polymerization initiator. The curable composition may further contain other components as necessary.
Below, each component contained in the said curable composition is demonstrated.

[Curable resin]
The curable resin is not particularly limited as long as it is a resin that is cured by irradiation with energy rays or heating. The curable resin is preferably at least one selected from a hydrogenated conjugated diene-aromatic vinyl copolymer having a polymerizable unsaturated group and a urethane liquid oligomer having a polymerizable unsaturated group. From the viewpoint of water vapor barrier properties, the hydrogenated conjugated diene-aromatic vinyl copolymer is preferable, and from the viewpoint of suppressing adsorption of siloxane, the urethane liquid oligomer is preferable.

The heat transfer sheet includes the hydrogenated conjugated diene-aromatic vinyl copolymer, thereby being excellent in water vapor barrier properties, and including the urethane liquid oligomer hardly adsorbs siloxane present in the air.
In addition, the heat transfer sheet does not require a high filler filling rate in order to obtain excellent thermal conductivity, so the sheet has high flexibility and excellent sealing performance.
Therefore, the heat transfer sheet is excellent in protection performance for protecting the quality of electronic components and the like.

-Hydrogenated conjugated diene-aromatic vinyl copolymer having a polymerizable unsaturated group-
The polymerizable unsaturated group contained in the hydrogenated conjugated diene-aromatic vinyl copolymer is not particularly limited, but is particularly preferably a (meth) acryloyl group.

Examples of the conjugated diene monomer constituting the hydrogenated conjugated diene-aromatic vinyl copolymer include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 2-phenyl-1 , 3-butadiene, 1,3-hexadiene and the like. Among these, 1,3-butadiene and / or isoprene are preferable from the viewpoint of securing elasticity of the rubber after curing, and 1,3-butadiene is particularly preferable. These may be used alone or in combination of two or more.
As the aromatic vinyl monomer constituting the hydrogenated conjugated diene-aromatic vinyl copolymer, styrene, α-methylstyrene or paramethylstyrene is preferable from the viewpoint of the physical properties of the rubber after curing, and styrene It is particularly preferred. These may be used alone or in combination of two or more.
In the hydrogenated conjugated diene-aromatic vinyl copolymer, the content of structural units derived from the conjugated diene monomer is preferably 10 to 40% by mass, and more preferably 15 to 30% by mass. . The hydrogenated conjugated diene-aromatic vinyl copolymer preferably has a number average molecular weight of 10,000 to 20,000, more preferably 15,000 to 18,000.
As the hydrogenated conjugated diene-aromatic vinyl copolymer, a copolymer containing a structural unit derived from 1,3-butadiene and a structural unit derived from styrene is preferable, and an acryloyl group-containing hydrogenated styrene-butadiene copolymer is preferable. The coalescence is most preferred.

The hydrogenated conjugated diene-aromatic vinyl copolymer is preferably produced by the following method.
(I) A conjugated diene monomer and an aromatic vinyl monomer are polymerized with a dilithium initiator in a saturated hydrocarbon solvent to obtain a weight average molecular weight of 5,000 to 40,000 and a molecular weight distribution of 3.0 or less. Producing a conjugated diene-aromatic vinyl copolymer having:
(Ii) reacting the conjugated diene-aromatic vinyl copolymer with an alkylene oxide to produce a conjugated diene-aromatic vinyl copolymer polyol;
(Iii) hydrogenating the conjugated diene-aromatic vinyl copolymer polyol to produce a hydrogenated conjugated diene-aromatic vinyl copolymer polyol;
(Iv) reacting the hydrogenated conjugated diene-aromatic vinyl copolymer polyol with a polymerizable unsaturated group-containing compound;
It is a manufacturing method containing.

As the first step (i), a conjugated diene-aromatic vinyl copolymer is produced by polymerizing a conjugated diene monomer and an aromatic vinyl monomer with a dilithium initiator in a saturated hydrocarbon solvent. . Since the main polymerization is living anionic polymerization, the polymerization can be performed while controlling the molecular weight and molecular weight distribution. The molecular weight can be obtained by polymerizing a polymer having a predetermined molecular weight depending on the amount of the dilithium initiator and the above monomer. In particular, when the weight average molecular weight is 5,000 or more, a narrow polymer having a molecular weight distribution of 2 or less is used. Easy to get. If desired, anionic polymerization may be performed in the presence of a randomizer.
Next, as a second step (ii), the conjugate of the above conjugated diene-aromatic vinyl copolymer is a conjugate having hydroxyl groups at both ends by an equivalent reaction between the copolymer terminal which is a living anion and alkylene oxide. A diene-aromatic vinyl copolymer polyol can be obtained.
Furthermore, as a third step (iii), a hydrogenation reaction (hereinafter referred to as a hydrogenation reaction) is performed on the conjugated diene-aromatic vinyl copolymer polyol having a double bond in the main chain. A hydrogenated conjugated diene-aromatic vinyl copolymer polyol having no unsaturated double bonds in the chain or few unsaturated double bonds in the main chain can be obtained.
As a fourth step (iv), the above hydrogenated conjugated diene-aromatic vinyl copolymer polyol is reacted with a polymerizable unsaturated group-containing compound to give a hydrogenated conjugated diene-aromatic having a polymerizable unsaturated group. A vinyl group copolymer is obtained.

The dilithium initiator used in the first step (i) is not particularly limited, and known ones can be used. For example, Japanese Patent Publication No. 1-53681 discloses a method for producing a dilithium initiator by reacting a monolithium compound with a disubstituted vinyl or an alkenyl group-containing aromatic hydrocarbon in the presence of a tertiary amine. ing.
Monolithium compounds used when producing a dilithium initiator include ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, tert-butyl lithium, tert-octyl lithium, and n-decyl. Examples of the lithium include phenyl lithium, 2-naphthyl lithium, 2-butyl-phenyl lithium, 4-phenyl-butyl lithium, cyclohexyl lithium, and cyclopentyl lithium. Among these, sec-butyl lithium is preferable.
Examples of the tertiary amine used when producing the dilithium initiator include lower aliphatic amines such as trimethylamine and triethylamine, N, N-diphenylmethylamine, and the like, and triethylamine is particularly preferable.
Examples of the disubstituted vinyl or alkenyl group-containing aromatic hydrocarbon include 1,3- (diisopropenyl) benzene, 1,4- (diisopropenyl) benzene, 1,3-bis (1-ethylethenyl). ) Benzene, 1,4-bis (1-ethylethenyl) benzene and the like are preferred.

  The solvent used in the preparation of the dilithium initiator and the production of the copolymer may be an organic solvent inert to the reaction, and is a hydrocarbon solvent such as an aliphatic, alicyclic, or aromatic hydrocarbon compound. For example, n-butane, l-butane, n-pentane, l-pentane, cis-2-butene, trans-2-butene, l-butene, n-hexane, n-heptane, n-octane, One or two kinds selected from l-octane, methylcyclopentane, cyclopentane, cyclohexane, 1-hexene, 2-hexene, 1-pentene, 2-pentene, benzene, toluene, xylene, ethylbenzene and the like are used. Of these, n-hexane and cyclohexane are usually used.

  Examples of the alkylene oxide used in the second stage (ii) include ethylene oxide, propylene oxide, butylene oxide and the like. This polyol reaction is preferably performed immediately after the polymerization reaction.

If the weight average molecular weight of the conjugated diene-aromatic vinyl copolymer polyol having hydroxyl groups at both ends obtained by the polyolization reaction in the second stage (ii) is 5,000 or more, the molecular weight between cross-linking points is increased. It is preferable as a rubber material because the modulus of elasticity can be lowered and the elongation can be increased after the photocuring reaction. Since it does not become too high and it is not necessary to lower the solid content concentration as a polymerization process, it is preferable because the cost is low.
Moreover, various influences by a low molecular weight component and a high molecular weight component can be suppressed as molecular weight distribution is 3.0 or less. In particular, since the viscosity is greatly affected by the molecular weight, slight fluctuations in the molecular weight cause viscosity variations. In the present invention in which a copolymer having a narrow molecular weight distribution can be synthesized, a copolymer having the same molecular weight can be obtained with good reproducibility, so that an effect of stabilizing the viscosity can be expected. In many cases, the liquid material as in the present invention is applied by a dispenser. In this case, since the variation in the material viscosity causes a variation in the dimension after the application, the stabilization of the viscosity is important, and the molecular weight distribution is 3. It is preferably 0 or less.

The hydrogenation reaction in the third stage (iii) is performed by hydrogenating the conjugated diene-aromatic vinyl copolymer polyol in an organic solvent in the presence of a hydrogenation catalyst under hydrogen pressure. The hydrogenation catalyst used in this hydrogenation reaction is a heterogeneous catalyst such as palladium-carbon, reduced nickel or rhodium; or an organic nickel compound such as nickel naphthenate or nickel octoate, or cobalt naphthenate or cobalt octoate. A homogeneous catalyst in which an organocobalt compound and an organoaluminum compound such as triethylaluminum and triisobutylaluminum or an organolithium compound such as n-butyllithium and sec-butyllithium are combined can be used. As a cocatalyst, an ether compound such as tetrahydrofuran, ethylene glycol dimethyl ether, or diethylene glycol dimethyl ether may be used. Other hydrogenation reaction methods include, for example, a copolymer before hydrogenation, dicyclopentadienyl titanium halide, organic carboxylate nickel, organic carboxylate nickel, and organic metals of Groups I to III of the periodic table. A hydrogenation catalyst composed of a compound, nickel, platinum, barium, ruthenium, rhenium, rhodium metal catalyst supported on carbon, silica, diatomaceous earth, etc., cobalt, nickel, rhodium, ruthenium complex, etc. Under hydrogen pressurized to a certain degree, or in the presence of lithium aluminum hydride, p-toluenesulfonyl hydrazide, Zr—Ti—Fe—V—Cr alloy, Zr—Ti—Nb—Fe—V—Cr alloy, LaNi ₅ Pressurized in the presence of a hydrogen storage alloy such as an alloy or about 0.1 MPa to 10 MPa Obtained by mixing hydrogenated di-p-tolyl-bis (1-cyclopentadienyl) titanium / cyclohexane solution and n-butyllithium / n-hexane solution under hydrogen. Examples thereof include a method of performing hydrogenation under hydrogen pressurized to about 0.1 MPa to 10 MPa using the hydrogenation catalyst obtained.

Among the various hydrogenation catalysts described above, a Ziegler hydrogenation catalyst or a palladium-carbon hydrogenation catalyst comprising a combination of a transition metal compound and an alkylaluminum compound is preferred.
Such transition metal compounds include tris (acetylacetonato) cobalt, bis (acetylacetonato) nickel, tris (acetylacetonato) iron, tris (acetylacetonato) chromium, tris (acetylacetonato) manganese, bis (acetyl). Acetonato) manganese, tris (acetylacetonato) ruthenium, bis (acetylacetonato) cobalt, bis (cyclopentadienyl) dichlorotitanium, bis (cyclopentadienyl) dichlorozirconium, bis (triphenylphosphine) cobalt dichloride, Examples thereof include bis (2-hexanoate) nickel, bis (2-hexanoate) cobalt, titanium tetraisopropoxide, and titanium tetraethoxide. Among these, bis (acetylacetonato) nickel and tris (acetylacetonato) cobalt are preferable from the viewpoint of high hydrogenation activity.

  Alkyl aluminum compounds used for Ziegler hydrogenation catalysts include trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, tri-n-butylaluminum, dimethylaluminum chloride, diethylaluminum chloride, diisobutylaluminum chloride, methylaluminum. Examples include dichloride, ethylaluminum dichloride, isobutylaluminum dichloride, diethylaluminum hydride, diisobutylaluminum hydride, ethylaluminum sesquichloride and the like. Among these, triisobutylaluminum, triethylaluminum, and diisobutylaluminum hydride are preferable from the viewpoint of hydrogenation activity, and triisobutylaluminum is most preferable.

  Although there is no particular limitation on the use form of the Ziegler-type hydrogenation catalyst in the hydrogenation reaction, a method in which a catalyst solution in which a transition metal compound and an alkylaluminum compound are reacted in advance is prepared and added to the polymerization solution is preferably cited. Can do. The amount of the alkylaluminum compound used in this case is preferably 0.2 mol to 5 mol with respect to 1 mol of the transition metal compound. The reaction for preparing the catalyst is performed at a temperature range of about -40 ° C to 100 ° C, preferably 0 ° C to 80 ° C, and the reaction time is usually in the range of 1 minute to 3 hours.

  The hydrogenation reaction is usually performed at a temperature of 50 ° C. to 180 ° C., preferably 70 ° C. to 150 ° C., with a hydrogen pressure of about 0.5 MPa to 10 MPa, preferably 1 MPa to 5 MPa. When the hydrogenation temperature is 50 ° C. or higher and the hydrogen pressure is 0.5 MPa or higher, the catalytic activity is good. When the hydrogenation temperature is 180 ° C. or lower, the catalyst is hardly deactivated, side reaction or the like hardly occurs. In general, the Ziegler hydrogenation catalyst is a catalyst with extremely high hydrogenation activity, and the hydrogen pressure may be 10 MPa or less, and if it is 10 MPa or less, the burden on the apparatus is small.

In the fourth stage (iv), the hydrogenated copolymer polyol is reacted with a polymerizable unsaturated group-containing compound, particularly preferably a (meth) acryloyl group-containing compound. Here, the (meth) acryloyl group-containing compound is preferably acryloyloxyalkyl isocyanate or methacryloyloxyalkyl isocyanate, and the hydrogenated copolymer polyol is (meth) acrylated by reaction with these.
Examples of the acryloyloxyalkyl isocyanate include 2-acryloyloxyethyl isocyanate, and examples of the methacryloyloxyalkyl isocyanate include 2-methacryloyloxyethyl isocyanate.

  In the present invention, the hydrogenated conjugated diene-aromatic vinyl copolymer may be used singly or in combination of two or more.

-Urethane liquid oligomer having a polymerizable unsaturated group-
The urethane liquid oligomer is cross-linked by irradiating with ultraviolet rays, α rays, β rays, γ rays, electron beams, etc., or by heating, those having energy quanta in electromagnetic waves or charged particle beams. Refers to urethane liquid oligomer.
The urethane liquid oligomer is preferably an unsaturated group-containing urethane oligomer having a structure represented by the following general formula (I) and having a number average molecular weight of 5 × 10 ^{3 to} 5 × 10 ⁴ .

In the general formula (I), R ¹ is a dehydroxylated residue of a monol compound containing an unsaturated group of at least ^one of a (meth) acryloyl group and a vinyl group.
Preferred examples of the monool compound include hydroxyalkyl (meth) acrylate and hydroxyalkyl vinyl. Examples thereof include diethylene glycol mono (meth) acrylate, dipropylene glycol mono (meth) acrylate, tripropylene glycol mono (meth) acrylate, and triethylene. Examples include glycol mono (meth) acrylate and polyethylene glycol mono (meth) acrylate.
R ¹ is preferably a dehydroxylated residue of either a hydroxyalkyl (meth) acrylate (such as hydroxyethyl acrylate) or a hydroxyalkyl vinyl ether (such as hydroxymethyl vinyl ether).

In the general formula (I), R ² is a deisocyanate residue of the organic diisocyanate compound. For example, alkylene groups such as methylene group, ethylene group, propylene group, butylene group and hexamethylene group, cycloalkylene groups such as cyclohexylene group, arylene groups such as phenylene group, tolylene group and naphthylene group, xylylene groups and the like are included. Here, the alkyl group may be linear, branched or cyclic. Organic diisocyanate compounds include isophorone diisocyanate, hexamethylene diisocyanate, norbornane diisocyanate, tolylene diisocyanate, xylene diisocyanate, trimethylhexamethylene diisocyanate, naphthalene diisocyanate, hydrogenated xylates. Preferred examples include range isocyanate, hydrogenated diphenylmethane diisocyanate, diphenylmethane diisocyanate, and the like.

In the general formula (I), R ³ is a dehydroxylated residue of a polyester diol compound having a number average molecular weight of 1 × 10 ³ to 1 × 10 ⁴ and containing a cyclic group or a branched chain group.
Among these, R ³ is a dehydrogenation residue of the polyester diol compound in which a cyclic group-containing dicarboxylic acid and a diol are condensed, or a dehydrogenation of a polyester diol compound in which a cyclic group-containing dicarboxylic acid anhydride is modified by reacting with the diol. Hydroxyl residues are preferred.

In the general formula (I), examples of the cyclic group-containing dicarboxylic acid or acid anhydride constituting R ³ include phthalic acid, phthalic anhydride, pyromellitic acid, pyromellitic anhydride, isophthalic acid, trimellitic acid, anhydrous Examples include trimellitic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, and hexahydrophthalic anhydride. Moreover, you may use these in mixture of multiple types.
In the general formula (I), examples of the diol constituting R ³ include ethylene glycol, propylene glycol, 2,2,4-trimethyl-1,3-pentanediol, neopentyl glycol, 1,2-propanediol, 1, 3-propanediol, 1,4-propanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, bisphenol A, 2 , 2-thiodiethanol, acetylene-type diol, hydroxy-terminated polybutadiene, 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-bis (2-hydroxyethoxy) cyclohexane , Trimethylene glycol, tetramethylene Recall, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, norbornylene glycol, 1,4-benzenedimethanol, 1,4-benzenediethanol, 2,4-dimethyl- 2-ethylenehexane-1,3-diol, 2-butene-1,4-diol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-2-butyl-1,3-propanediol, 3 -Methyl-1,5-pentanediol and the like.

In general formula (I), A is a dehydrogenation residue of a diamine compound or a dehydrogenation residue of a diol compound. Such a dehydrogenated residue is not particularly limited, and examples thereof include diaminopropane, diaminobutane, nonanediamine, isophoronediamine, hexamethylenediamine, hydrogenated diphenylmethanediamine, bisaminopropyl ether, bisaminopropylethane, Dehydrogenation residue of a diamine compound selected from bisaminopropyl diethylene glycol ether, bisaminopropyl polyethylene glycol ether, bisaminopropoxyneopentyl glycol, diphenylmethanediamine, xylylenediamine, tolylenediamine, and both-terminal amino group-modified silicones; ethylene Glycol, propylene glycol, polyethylene glycol, polypropylene glycol, butylene glycol, polytetramethylene glycol, pen Njioru, hexanediol, dehydrogenation residue of hydroxyl groups at both ends modified silicone, and a diol compound selected from the carboxyl group-containing diol are preferred.
In general formula (I), each of p and r is 0-7, and q is 0-3. However, when q = 0, 1 ≦ p + r ≦ 10.

The urethane liquid oligomer can be preferably produced by the following method.
The unsaturated group-containing urethane oligomer when q = 0 in the general formula (I) is an adduct having an isocyanate group at both ends by polyaddition reaction of the polyester diol compound and the organic diisocyanate compound. After the formation, it can be obtained by adding the monool compound to the isocyanate group.
Further, the unsaturated group-containing urethane oligomer in the case of q ≠ 0 in the general formula (I) is an addition having an isocyanate group at both ends by polyaddition reaction of the polyester diol compound and the organic diisocyanate compound. After forming the product, each of the diamine compound or each end of the diol compound is added to an isocyanate group at one end of the adduct, and the monool compound is added to the isocyanate group at the other end of the adduct. It can be obtained in addition.

The urethane liquid oligomer has an effect of imparting appropriate rubber elasticity to the sheet substrate and improving the sealing property of the sheet substrate when the curable composition is cured by energy ray irradiation or heat to produce a sheet substrate. Demonstrate. From the viewpoints of this effect and moldability, the number average molecular weight of the urethane liquid oligomer is usually preferably about 5 × 10 ^{3 to} 5 × 10 ⁴ although it depends on the structure.
In the present invention, one type of the urethane liquid oligomer may be used, or two or more types may be used in combination.

Other examples of the curable resin include silicone rubbers such as dimethyl silicone rubber, methyl vinyl silicone rubber, and methyl phenyl vinyl silicone rubber.
As the silicone rubber, addition-type silicone rubber, fluorosilicone rubber or the like may be used. For example, “X-32-1342,” “X-31-7006,” “KE1051,” “ KE110Gel "," KE104Gel "," FE53 "," KE-2000-60A "," KE-2000-60B "," KE-1204 ", and the like can be used.

[(Meth) acrylate monomer]
The (meth) acrylate monomer contained in the curable composition has an ester residue of an alkyl group having 8 to 18 carbon atoms, isobornyl group, cyclohexyl group, dicyclopentanyl group, dicyclopentenyl group, dicyclopentanyl. It is preferably an oxyethyl group, a dicyclopentenyloxyethyl group or a nonylphenoxy polyalkylene glycol residue. Here, the polyalkylene glycol is preferably polyethylene glycol and / or polypropylene glycol. In addition, the ester residue of a (meth) acrylate monomer means the residue remove | excluding one hydroxyl group of the hydroxyl group containing compound among the (meth) acrylic acid and hydroxyl group containing compound which comprise a (meth) acrylate monomer.
By combining the curable liquid resin and the (meth) acrylate monomer, a good compatibility can be obtained, and a curable composition having little low moisture permeability can be obtained with little adsorption of siloxane present in the air. Can be obtained.

  Specific examples of the (meth) acrylate monomer include isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, isostearyl (meth) acrylate, and isomyristyl (meth) acrylate. , Lauryl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, nonylphenoxypolyethylene glycol (meth) acrylate, nonylphenoxypolypropylene glycol (meth) acrylate, nonylphenoxypolyethylene glycol -Polypropylene glycol (meth) acrylate, nonylphenoxy polypropylene glycol-polyethylene glycol (meth) acrylate And the like.

  The blending amount of the (meth) acrylate monomer is 100 parts by mass when the curable liquid resin and the (meth) acrylate monomer are combined, and the ratio of the parts by mass (curable liquid resin / (meth) acrylate monomer) is: It is preferably (20/80) to (100/0), and more preferably (30/70) to (90/10). When the (meth) acrylate monomer is 10 parts by mass or more, the effect of reducing the viscosity of the curable composition can be enjoyed, and extrusion, discharge, and the like are facilitated, and formation is facilitated. Moreover, if it is 70 mass parts or less, the viscosity of a composition will not become low too much and it will become difficult to flow down the sheet | seat base | substrate immediately after formation. Furthermore, the elasticity of the sheet substrate after curing is ensured.

  In the present invention, in addition to the (meth) acrylate monomer, a terminal (meth) acrylate oligomer can be blended if desired. By blending this terminal (meth) acrylate oligomer, the viscosity of the curable composition can be adjusted, and physically, a decrease in hardness, an improvement in Eb (elongation) and Tb (breaking strength), etc. Can be achieved. The terminal (meth) acrylate oligomer refers to an oligomer having an acryloyl group or a methacryloyl group at one end or both ends.

  Examples of the terminal (meth) acrylate oligomer include polyester (meth) acrylate oligomers, epoxy (meth) acrylate oligomers, urethane (meth) acrylate oligomers, polyol (meth) acrylate oligomers, and the like. As the polyester (meth) acrylate oligomer, for example, by esterifying the hydroxyl group of a polyester oligomer having hydroxyl groups at both ends obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol with (meth) acrylic acid, or It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding an alkylene oxide to a polyvalent carboxylic acid with (meth) acrylic acid. The epoxy (meth) acrylate oligomer can be obtained, for example, by reacting (meth) acrylic acid with an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolak type epoxy resin and esterifying it. Alternatively, it can be modified with isocyanate and the terminal hydroxyl group can be esterified with acrylic acid. The polyol (meth) acrylate-based oligomer can be obtained by esterifying the hydroxyl group of the polyether polyol with (meth) acrylic acid. The urethane (meth) acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by a reaction of polyether polyol or polyester polyol and polyisocyanate with (meth) acrylic acid.

-Monofunctional (meth) acrylate monomer-
Among (meth) acrylate monomers, monofunctional (meth) acrylate monomers (hereinafter referred to as “low Tg monofunctional (meth) acrylate monomers”) having a glass transition temperature (Tg) of a homopolymer cured product of −70 ° C. to 20 ° C. Is preferred). The use of a low Tg monofunctional (meth) acrylate monomer is advantageous in that it imparts appropriate flexibility and tackiness to the heat transfer sheet and can reduce the thermal resistance between the heat transfer sheet and the heating element and heat receiving element. is there. The transition temperature (Tg) is more preferably −70 ° C. to 0 ° C.
In addition, the said transition temperature (Tg) is the value which measured the polymer obtained by superposing | polymerizing by the normal radical polymerization method on normal conditions with the differential scanning calorimeter (DSC).

  As said low Tg monofunctional (meth) acrylate monomer, what has Tg in the said range suitably from the (meth) acrylic acid ester compound represented, for example by the following general formula (II) and general formula (III) suitably You can choose.

In the general formula (II), R ⁴ represents a hydrogen atom or a methyl group, and R ⁵ represents a linear or branched alkyl group having 8 to 20 carbon atoms. Examples of the alkyl group represented by R ⁵ include various decyl groups, various dodecyl groups, various tetradecyl groups, various hexadecyl groups, various octadecyl groups, and the like.

In the general formula (III), ^{A 1} represents an alkylene group having 2 to 4 carbon atoms. The alkylene group may be linear or branched, and examples thereof include an ethylene group, a propylene group, a trimethylene group, a tetramethylene group, and a 1-methylpropylene group. Among these, an ethylene group And a propylene group are preferable, and an ethylene group is particularly preferable. R ⁶ represents a hydrogen atom or a methyl group, and R ⁷ represents an alkyl group having 6 to 20 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms.
The alkyl group having 6 to 20 carbon atoms in R ⁷ may be linear or branched, and specifically, various hexyl groups, various octyl groups, various decyl groups, various dodecyl groups, Examples include various tetradecyl groups, various hexadecyl groups, and various octadecyl groups. In the aralkyl group having 7 to 20 carbon atoms, a linear or branched alkyl group having about 1 to 15 carbon atoms may be introduced on the aromatic ring, specifically, a benzyl group, an alkylbenzyl group, or phenethyl. Group, alkylphenethyl group, naphthylmethyl group, alkylnaphthylmethyl group and the like. The aryl group having 6 to 20 carbon atoms may have a linear or branched alkyl group having about 1 to 15 carbon atoms introduced on the aromatic ring, specifically a phenyl group or an alkylphenyl group. , A naphthyl group, an alkylnaphthyl group, and the like.
n is a number of 1 to 7 on average, and when n is large, it is difficult to receive oxygen inhibition during curing, and as a result, surface tack becomes small, but the moisture permeability of the cured product tends to decrease. n is preferably about 1 to 4 on average from the viewpoint of the balance between tack and moisture permeability.

  One monofunctional (meth) acrylate monomer may be used alone, or two or more monofunctional (meth) acrylate monomers may be used in combination.

(Polymerization initiator)
As a polymerization initiator, a photoinitiator, a thermal polymerization initiator, etc. are mentioned, for example, It can select arbitrarily according to the kind of energy to provide.

As the photopolymerization initiator, either an intramolecular cleavage type or a hydrogen abstraction type may be used, and an intramolecular cleavage type and a hydrogen abstraction type may be used in combination.
Examples of intramolecular cleavage types include aminoacetophenones, benzoin derivatives, benzyl ketals, hydroxyacetophenones, combined use of aminoacetophenones and thioxanthones (eg, isopropylthioxanthone, diethylthioxanthone), acylphosphine oxides, and the like. Examples of the hydrogen abstraction type include combined use of benzophenones and amines, combined use of thioxanthone and amines, and the like.

Examples of aminoacetophenones include 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one [manufactured by Ciba Specialty Chemicals Co., Ltd., trade name: Irgacure 907], 2 -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone [Ciba Specialty Chemicals Co., Ltd., trade name: Irgacure 369], 2- (dimethylamino) -2-[(4 -Methylphenyl) methyl] -1- (4-morpholinophenyl) -1-butanone [Ciba Specialty Chemicals Co., Ltd., trade name: Irgacure 379] and the like. Aminoacetophenones may be used alone or in combination with other photopolymerization initiators.
Aminoacetophenones are highly reactive as photopolymerization initiators, and are less susceptible to oxygen inhibition of the surface of the curable composition due to the presence of nitrogen atoms, so that the curable composition is hardened and the molded product is cured. The tackiness (tackiness) can be reduced and the compression set can be reduced.

  Examples of the benzoin derivatives include benzoin, benzoin alkyl ether (alkyl having 1 to 6 carbon atoms), specifically, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, and the like. Examples of benzyl ketals include 2,2-dimethoxy-1,2-diphenylethane-1-one [manufactured by Ciba Specialty Chemicals, Inc., trade name: Irgacure 651]. Examples of hydroxyacetophenones 2-hydroxy-2-methyl-1-phenyl-propan-1-one [manufactured by Ciba Specialty Chemicals Co., Ltd., trade name: Darocur 1173], 1-hydroxy-cyclohexyl-phenyl ketone [Ciba Specialty Chemicals Product name: Irgacure 184], 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one [Product name: Irgacure 127, manufactured by Ciba Specialty Chemicals Co., Ltd.] It is below. And a combination of aminoacetophenones and thioxanthones (eg, isopropylthioxanthone, diethylthioxanthone), acylphosphine oxides {eg, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide [Ciba Specialty Chemicals (Product name: Irgacure 819]}, etc., and oligomerized α-hydroxyacetophenone {specifically, oligo [2-hydroxy-2-methyl-1- [4- (1-methylvinyl) ) Phenyl] propanone, such as Lamberti S. et al. p. Manufactured by A, trade name: ESACURE KIP150, etc.] and acrylated benzophenones [specifically, acrylated benzophenone, for example, manufactured by Daicel UC Corporation, trade name: Ebecryl P136, etc.] Can be mentioned.

  Further, benzoyl methyl ether, benzoyl ethyl ether, benzoyl butyl ether, benzoyl isopropyl ether, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, 2-hydroxy-2-methyl- [4- (1-methylvinyl) phenyl ] Propanol oligomer, 2-hydroxy-2-methyl- [4- (1-methylvinyl) phenyl] propanol oligomer and 2-hydroxy-2-methyl-1-phenyl-1-propanone, isopropylthioxanthone, o-benzoyl Examples thereof also include methyl benzoate, [4- (methylphenylthio) phenyl] phenylmethane, and imide acrylate.

As the thermal polymerization initiator, either a thermal radical polymerization initiator or a thermal cationic polymerization initiator may be used.
As thermal radical polymerization initiators, azo initiators, ketone peroxide initiators, peroxyketal initiators, hydroperoxide initiators, dialkyl peroxide initiators, diacyl peroxide initiators, peroxy Examples thereof include ester initiators, peroxycarboxylic acid initiators, and peroxydicarbonate initiators.
The thermal cationic polymerization initiator is a commercially available product, Sun-Aid SI-45, SI-47, SI-60, SI-60L, SI-80, SI-80L, SI-100, SI-100L, SI-145. SI-150, SI-160, SI-110L, SI-180L (above, trade names manufactured by Sanshin Chemical Industry Co., Ltd.), CI-2920, CI-2921, CI-2946, CI-3128, CI- 2624, CI-2639, CI-2064 (above, trade names made by Nippon Soda Co., Ltd.), CP-66, CP-77 (above, trade names made by Asahi Denka Kogyo Co., Ltd.), FC-520 (3M (Trade name made by Co., Ltd.), Kayaester O-50 (trade name made by Kayaku Akzo Co., Ltd.), and the like.

The kind of the polymerization initiator can be selected according to the miscibility with the curable liquid resin or the (meth) acrylate monomer, the curing conditions, and the like.
The amount of the polymerization initiator blended in the curable composition is preferably 0.1 to 6 parts by mass, more preferably 100 parts by mass in total of the curable liquid resin and the (meth) acrylate monomer. It is 0.5-5 mass parts, More preferably, it is 1-4 mass parts.

[Other ingredients]
The curable composition may further contain a thixotropic agent from the viewpoint of processability. By using a thixotropy imparting agent, thixotropy is effectively improved, and processing can be performed while accurately controlling the extrusion shape. As the thixotropic agent, both inorganic fillers and organic thickeners can be used.
Examples of the inorganic filler include surface-treated fine silica of wet silica and dry silica, and natural minerals such as organic bentonite. Specifically, silica fine powder pulverized by a dry method [for example, product name: Aerosil 300 manufactured by Nippon Aerosil Co., Ltd.], fine powder obtained by modifying this silica fine powder with trimethyldisilazane [for example, Nippon Aerosil Product name: Aerosil RX300, etc.] and fine powder obtained by modifying the above silica fine powder with polydimethylsiloxane [for example, product name: Aerosil RY300, manufactured by Nippon Aerosil Co., Ltd.]. The average particle diameter of the inorganic filler is preferably 5 μm to 50 μm, more preferably 5 μm to 12 μm, from the viewpoint of thickening.

  Examples of the organic thickener include amide wax, hydrogenated castor oil, or a mixture thereof. Specifically, hydrogenated castor oil which is a hydrogenated product of castor oil (non-drying oil whose main component is ricinoleic acid) [for example, manufactured by Zude Chemie Catalysts Co., Ltd., trade name: ADVITOLL 100, manufactured by Enomoto Kasei Co., Ltd., product Name: Disparon 305 etc.] and high-grade amide wax which is a compound obtained by substituting hydrogen of ammonia with an acyl group [for example, trade name: Disparon 6500, etc., manufactured by Enomoto Kasei Co., Ltd.].

In the present invention, the thixotropic agent is preferably an organic thickener. Natural mineral-based inorganic fillers cannot avoid impurities such as heavy metals, and surface-treated fine silica may change the wettability of the surface and change the viscosity of the composition, and depending on the type of surface treatment agent May generate harmful gas to the equipment during use.
Among organic thickeners, amide wax is particularly preferably hydrogenated castor oil because the presence of amine derived from the raw material may increase the crosslinking density and increase the hardness.

  The thixotropic agent is preferably contained in an amount of 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the curable liquid resin.

  The curable composition may further contain a crosslinking agent. As the crosslinking agent, organic peroxides are preferably exemplified. Specifically, for example, 2,5-dimethyl-2,5-di (t-butylperoxy) -hexane; 2,5-dimethyl-2 , 5-di (benzoylperoxy) -hexane; t-butylperoxybenzoate; dicumyl peroxide; t-butylcumyl peroxide; diisopropylbenzohydroperoxide; 1,3-bis- (t-butylperoxy Isopropyl) -benzene; benzoyl peroxide; 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane and the like.

The curable composition may further contain a stabilizer and the like. As a stabilizer, triethylene glycol bis [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionate] [for example, Ciba Specialty Chemicals Co., Ltd., trade name: IRGANOX245, Asahi Manufactured by Denka Kogyo Co., Ltd., trade name: ADK STAB AO-70, etc.], 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1, 1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5,5] undecane [for example, manufactured by Asahi Denka Kogyo Co., Ltd., trade name: ADK STAB AO-80, etc.] Etc.
The amount of the stabilizer added to the curable composition is preferably 0.1 to 5 parts by mass, more preferably 0 to 100 parts by mass in total of the curable liquid resin and the (meth) acrylate monomer. 0.5-3 parts by mass, more preferably 0.5-2 parts by mass.

The curable composition may contain other monomer, for example, a (meth) acrylic acid ester-based monomer, as necessary, as long as the object of the present invention is not impaired.
In addition to thixotropic agents, clay-like inorganic additives such as clay, diatomaceous earth, talc, barium sulfate, calcium carbonate, magnesium carbonate, metal oxides, mica, graphite, aluminum hydroxide, and various metal powders , Glass powder, ceramic powder, granular or powdered solid filler such as granular or powdered polymer, other various natural or artificial short fibers, long fibers (eg glass fiber, metal fiber, other various polymer fibers, etc.) Etc. can be blended.
Furthermore, weight reduction can be attained by mix | blending the hollow filler, for example, the organic hollow filler which consists of inorganic hollow fillers, such as a glass balloon, a polyvinylidene fluoride, a polyvinylidene fluoride copolymer. In addition, various foaming agents can be mixed in order to improve various physical properties such as weight reduction, and it is also possible to mix gas mechanically during mixing.

  Furthermore, if necessary, photosensitizers, thermal polymerization inhibitors, curing accelerators, flame retardants, antibacterial agents, hindered amine light stabilizers, UV absorbers, antioxidants, colorants such as titanium black, coumarone resin , Various adhesive elastomers such as coumarone-indene resin, phenol terpene resin, petroleum hydrocarbon, rosin derivative, etc. (tackfire), Rheostomer B (trade name: manufactured by Riken Vinyl Co., Ltd.), Hibler (product) Name: manufactured by Kuraray Co., Ltd., a block copolymer in which polystyrene blocks are connected to both ends of a vinyl-polyisoprene block), Norex (trade name: manufactured by Nippon Zeon Co., Ltd., polynorbornene obtained by ring-opening polymerization of norbornene), etc. Other thermoplastic elastomers or resins can be used in combination.

  The curable composition preferably has flexibility when cured. Specifically, the JIS A rubber hardness of the heat transfer sheet is preferably 50 or less, particularly preferably 30 or less. Here, the JIS A rubber hardness of the heat transfer sheet can be measured by a type A durometer based on JIS K 6253.

  The curable composition preferably has a viscosity at 25 ° C. of 0.1 mPa · s to 100 mPa · s. When the viscosity is 100 mPa · s or less, the magnetic particles are easily oriented in the sheet molding material in the magnetic field application step. On the other hand, when the viscosity is 0.1 mPa · s or more, the magnetic particles are unlikely to settle in the sheet molding material in the magnetic field application step and the curing step. The viscosity is more preferably 2 mPa · s to 50 mPa · s for the above reason. In addition, the viscosity of a curable composition is measured on 25 degreeC conditions using RS600 (product made from HAAKE).

[Method for producing curable composition]
The manufacturing method of the said curable composition is not specifically limited, A well-known method is applicable. For example, kneaders capable of adjusting the temperature of each component and the additive component used as required, for example, a single screw extruder, a twin screw extruder, a planetary mixer, a twin screw mixer, a high shear mixer, a stirring deaerator, etc. It can manufacture by kneading | mixing using.

[Magnetic particles]
The magnetic particles include a magnetic material at least partially. The magnetic particles are oriented in the direction of the magnetic field in the sheet molding material by the magnetic field application step.
The magnetic body may be a ferromagnetic body or a paramagnetic body, but a ferromagnetic body is preferable from the viewpoint of easy orientation in the sheet molding material in the magnetic field application step. The ferromagnetic material may be a soft magnetic material or a hard magnetic material, but is preferably a soft magnetic material from the viewpoint of excellent thermal conductivity of the obtained heat transfer sheet.

  The magnetic particles are preferably particles containing a soft magnetic material at least in part from the viewpoint of excellent thermal conductivity of the obtained heat transfer sheet. The reason why the heat conductivity of the obtained heat transfer sheet is excellent when the magnetic particles include the soft magnetic material is not necessarily clear, but the magnetic pole of the soft magnetic material is changed as the magnetic field direction of the alternating magnetic field is repeatedly reversed. It is presumed that repeated reversal improves the alignment state of the magnetic particles.

Examples of the magnetic particles include particles made of a soft magnetic material such as iron, nickel, cobalt, and alloys containing these. In addition, it is made of a hard magnetic material such as a metal oxide such as ferrite represented by the chemical formula: MO · Fe ₂ O ₃ [M is a metal selected from Mn, Fe, Ni, Cu, Mg, Zn, etc.] Particles.
As said magnetic particle, the particle | grains which consist of said soft magnetic material from a viewpoint with which the heat conductivity of the heat-transfer sheet | seat obtained are excellent are preferable, and the soft magnetic particle which consists of an alloy containing iron and iron is more preferable.

The shape of the magnetic particles is not particularly limited, and may be a true sphere, a spherically deformed sphere, or a rod.
The average particle diameter of the magnetic particles is preferably 10 μm to 500 μm. When the average particle diameter is 500 μm or less, the magnetic particles are easily oriented in the sheet molding material in the magnetic field application step. On the other hand, when the average particle diameter is 10 μm or more, the number of magnetic particles contained in one heat transfer path is not too large, and the number of paths between particles is not too large, so that the thermal conductivity is high. The average particle diameter is more preferably 20 μm to 200 μm, still more preferably 20 μm to 150 μm.
Here, the “particle diameter” represents an average particle diameter and can be measured using a laser scattering diffraction particle size distribution measuring apparatus or the like.

[Composite particles]
The magnetic particles are preferably composite particles in which at least a part of the surface of the substrate particles is coated with fine particles having a particle diameter smaller than that of the substrate particles.
Specifically, the magnetic particles are preferably composite particles in which the base particles are made of a magnetic material, and the fine particles are made of an insulating material and a highly thermally conductive material. The base particles made of a magnetic material orient the magnetic particles in a magnetic field. The fine particles made of a material having insulating properties and high thermal conductivity cause the magnetic particles to exhibit thermal conductivity and insulating properties. Therefore, when the composite particles are used as the magnetic particles, high thermal conductivity is obtained in the orientation direction of the magnetic particles, and insulation can be imparted to the sheet.

Examples of the particles made of a magnetic material constituting the substrate particle include particles made of the soft magnetic material described above and particles made of the hard magnetic material described above.
The base particle is preferably a soft magnetic material from the viewpoint of excellent thermal conductivity of the obtained heat transfer sheet, preferably a particle made of the soft magnetic material, and soft magnetic particles made of iron and an alloy containing iron. Is more preferable.

  As the highly heat conductive material having insulating properties constituting the fine particles, at least one material selected from ceramic materials and diamond is preferable. Examples of the ceramic material include aluminum nitride, boron nitride (boron nitride), silicon nitride, beryllium oxide, magnesium oxide, aluminum oxide, silicon carbide, and the like.

  As a constituent material of the fine particles, a metal hydroxide such as aluminum hydroxide can be used in addition to the above-described materials.

  When fine particles made of ceramic material, diamond and metal hydroxide are used as the fine particles, the fine particles have insulating properties. Therefore, even when particles made of a conductive material are used as the substrate particles, The heat transfer sheet can be made insulative by adjusting the coverage of the surface of the base particles.

The fine particles have a smaller diameter than the base particles. Specifically, the ratio of the particle diameter of the substrate particles to the particle diameter of the fine particles (substrate particles / fine particles) is preferably 30 to 500, and more preferably 50 to 300. Within the above range, the contact area between the base particles and the other fine particles is increased, heat conduction between the particles is performed smoothly, and the heat conductivity of the heat transfer sheet is good.
Here, the “particle diameter” represents an average particle diameter and can be measured using a laser scattering diffraction particle size distribution measuring apparatus or the like.

The base particles and the fine particles may have a true spherical shape or a flatly deformed spherical shape.
Specifically, the average particle diameter of the base particles is preferably 10 μm to 500 μm, more preferably 20 μm to 200 μm, and still more preferably 20 μm to 150 μm. On the other hand, the average particle size of the fine particles is preferably 0.1 μm to 10 μm.
When the average particle diameter of the base particles and the fine particles is in the above range, the composite particles are easily oriented in the sheet molding material in the magnetic field application step, and the number of composite particles included in one heat transfer path is The thermal conductivity is high because it is not too many and the number of paths between particles is not too many.

  In the composite particles, the mass ratio of the fine particles to the base particles is preferably 0.1 to 70 parts by mass, and more preferably 1 to 30 parts by mass with respect to 100 parts by mass of the base particles. .

In the composite particles, the coverage of fine particles on the surface of the base particles (ratio of the coated area of the fine particles to the surface area of the base particles) is preferably 10% or more. The heat conductivity which was excellent in the heat-transfer sheet | seat can be obtained because a coverage is 10% or more.
The coverage can be measured by using an electron microscope (SEM).

  The composite particles are particles in which at least a part of the surface of the substrate particles is coated with the fine particles. The fine particles are fixed by being adsorbed on the surface of the substrate particles. The adsorption of the fine particles on the surface of the substrate particle may be either physical adsorption or chemical adsorption.

As a method for producing the composite particles, a mechanochemical method in which the particles are composited by a mechanical force can be used. Specifically, base particles and particles to be fine particles are prepared, and these particles are mixed at a predetermined mixing ratio (mass ratio) according to the composite particles to be manufactured, and then using a hybridizer device, A method of performing a compounding process (encapsulation process) after performing a premixing process (OM process (precise mixing process)) as needed is suitably used. The composite treatment (encapsulation treatment) is performed under appropriate conditions according to the material of the base particles and fine particles, the particle diameter, and the mixing ratio (mass ratio) thereof. For example, the rotational speed is 13000 rpm and the treatment time is 5 minutes. .
The composite particles obtained by such a technique are obtained by attaching fine particles to the surface of the base particles by physical adsorption.

In the heat transfer sheet, the sheet base may contain nonmagnetic particles in addition to the magnetic particles.
Here, specific examples of the nonmagnetic particles include beryllium oxide (BeO), magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), boron nitride (BN), silicon nitride (SiN), and aluminum nitride (AlN). , Particles made of carbon black, copper, aluminum, gold, silver, carbon, silicon and the like.
When nonmagnetic particles are contained in the sheet substrate, the nonmagnetic particles are preferably contained in a volume fraction of 5 to 75%, more preferably 10 to 70%, still more preferably 30 to 50%. According to such a heat transfer sheet, in addition to heat conduction through a heat transfer path formed by a chain of magnetic particles, heat conduction is also performed through a heat transfer path formed by non-magnetic particles. Therefore, when the magnetic particles are oriented in the thickness direction of the sheet base, for example, higher thermal conductivity is obtained in the sheet thickness direction, and thermal conductivity is also obtained in the sheet surface direction.

  In the case of orienting the magnetic particles in the thickness direction of the sheet substrate, the heat transfer sheet is oriented in the sheet thickness direction from the viewpoint of improving workability of the heat transfer sheet or heat conductivity in the surface direction of the heat transfer sheet. A reinforcing sheet made of nylon mesh, metal mesh, or the like may be contained in the sheet substrate as long as it does not hinder the formation of the heat transfer path by the oriented magnetic particles.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Preparation of composite particles (1) to (5)]
Steel beads having an average particle diameter of 50 μm (manufactured by Niche, # 300) and the following various ceramic particles were prepared.
-Ceramic particles-
Silicon carbide (SiC): average particle size 0.6 μm, manufactured by Shinano Electric Smelting, SER-A06
Alumina: Average particle size 0.32 μm, Showa Denko, WA # 30000
Silicon nitride (SiN): average particle size 2.4 μm, manufactured by Denki Kagaku Kogyo, SN-9 FWS
Boron nitride (BN): average particle size 0.7 μm, manufactured by Denki Kagaku Kogyo, SP3-7
・ Aluminum nitride (AlN): average particle size 1μm, manufactured by Tokuyama

  The steel beads and any one of the ceramic particles were mixed so that the mass ratio (steel beads: ceramic particles) was 100: 6. Next, the mixed system of steel beads and ceramic particles is subjected to a composite treatment (encapsulation treatment) for 5 minutes using a hybridizer apparatus at a rotational speed of 13,000 rpm. Composite particles (1) to (5) in which the surface of the substrate particles was coated with fine particles made of ceramic particles were obtained. The composition of the composite particles (1) to (5) is shown in Table 1.

[Preparation of hydrogenated conjugated diene-aromatic vinyl copolymer]
An acryloyl group-containing hydrogenated styrene-butadiene copolymer was prepared by the following method.

After adding 1 mol of 1,3- (diisopropenyl) benzene to a fully dehydrated and purified cyclohexane solvent, 2 mol of triethylamine and 2 mol of sec-butyllithium are sequentially added and stirred at 50 ° C. for 2 hours. A dilithium polymerization initiator was prepared.
In a 7 liter polymerization reactor purged with argon, 1.90 kg of dehydrated and purified cyclohexane, 2.00 kg of a hexane solution of 22.9% by mass of 1,3 butadiene monomer, and a cyclohexane solution of 20.0% by mass of styrene monomer were added. After adding 130.4 ml of a hexane solution of 0.765 kg, 1.6 mol / liter of 2,2-di (tetrahydrofuryl) propane, 108.0 ml of a 0.5 mol / liter dilithium polymerization initiator was added. Polymerization was started.
Polymerization was carried out for 1.5 hours while raising the temperature of the polymerization reactor to 50 ° C., then 108.0 ml of a 1 mol / liter ethylene oxide cyclohexane solution was added, and the mixture was further stirred for 2 hours, and then 50 ml of isopropyl alcohol was added. did. A hexane solution of the copolymer was precipitated in isopropyl alcohol and sufficiently dried to obtain a copolymer polyol. This copolymer polyol was a OH group styrene-butadiene copolymer at both terminals, the styrene content was 25% by mass, the weight average molecular weight was 14,500, and the molecular weight distribution was 1.20.

Next, 120 g of copolymer polyol was dissolved in 1 liter of sufficiently dehydrated and purified hexane, and then a catalyst solution of nickel naphthenate, triethylaluminum, and butadiene prepared in a separate container in a ratio of 1: 3: 3 (molar ratio). Was charged so that the amount of nickel was 1 mol with respect to 1,000 mol of the butadiene portion in the copolymer solution. Hydrogen was added under pressure to 27,580 hPa (400 psi) in a sealed reaction vessel, and a hydrogenation reaction was performed at 110 ° C. for 4 hours. Thereafter, the catalyst residue was extracted and separated with hydrochloric acid of 3N concentration, and further centrifuged to separate the catalyst residue by sedimentation. Thereafter, the hydrogenated copolymer polyol was precipitated in isopropyl alcohol and further sufficiently dried.
100 g of a sufficiently dried hydrogenated copolymer polyol was dissolved in cyclohexane, and 2-acryloyloxyethyl isocyanate (Karenz AOI, manufactured by Showa Denko KK) was slowly added dropwise while maintaining the temperature at 40 ° C. with sufficient stirring. The mixture was stirred for 4 hours, precipitated in isopropyl alcohol and dried. The amount of 2-acryloyloxyethyl isocyanate added was 2.49 g. As described above, an acryloyl group-containing hydrogenated styrene-butadiene copolymer (hereinafter referred to as “H-SBR (1)”) was obtained.

[Preparation of urethane liquid oligomer]
A urethane liquid oligomer having a polymerizable unsaturated group was prepared by the following method.

400 g of polyester diol compound (number average molecular weight 2000) obtained from 2,4-diethyl-1,5-pentanediol and phthalic anhydride, 82.4 g of norbornane diisocyanate, and 2,6-antioxidant 0.10 g of di-t-butyl-4-methylphenol was added to a 1-liter four-necked flask equipped with a stirrer, a condenser, and a thermometer, and reacted at 80 ° C. for 2 hours. Next, 46.2 g of 2-hydroxyethyl acrylate, 0.10 g of p-methoxyphenol which is a polymerization inhibitor, and 0.06 g of titanium tetra (2-ethyl-1-hexanoate) as an addition reaction catalyst were added at 85 ° C. The reaction was performed for 6 hours. A part of the reaction solution was taken out, and the end point of the reaction was confirmed by the disappearance of the absorption peak of the isocyanate group at 2280 cm ^{−1 in} the infrared absorption spectrum to obtain a urethane oligomer (hereinafter referred to as “urethane oligomer (1)”). .
It was 18000 when the number average molecular weight was calculated | required by the polystyrene conversion value using the gel permeation chromatography about the urethane oligomer obtained above.

<Example 1>
[Manufacture of heat transfer sheet]
In a resin container, 50 g of H-SBR (1), 50 g of isomyristyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., light acrylate IM-A, glass transition temperature (Tg) -56 ° C. of cured product), photopolymerization initiator (BASF) 0.5 g of Irugacure 1173) and 50 g of steel beads (average particle size 50 μm, manufactured by Niche, # 300) were charged and stirred at room temperature to obtain a paste-like sheet molding material.

  A PET resin sheet (thickness 50 μm) is laid on a glass plate (thickness 3 mm), the thickness is determined by an ABS resin spacer (thickness 0.6 mm), and the sheet molding material is poured onto the PET resin sheet. It was. Another PET resin sheet (thickness: 50 μm) was placed on the sheet molding material so as not to enter air bubbles, and a glass plate (thickness: 3 mm) was further placed thereon and pressed from above to obtain a predetermined thickness. Thus, a laminated body in which a glass plate, a PET resin sheet, a sheet molding material layer, a PET resin sheet, and a glass plate were laminated in this order was obtained.

FIG. 8 is a cross-sectional view showing an outline of the AC magnetic field generator (Um-5BF manufactured by Electronic Magnetic Industry) used in this example.
The obtained laminate was installed in the AC magnetic field generator as shown in FIG. 8, and an AC magnetic field (100 millitesla, 50 Hz) was applied in the thickness direction of the laminate for 30 seconds at room temperature.
Subsequently, using a UV irradiation device (LC8 manufactured by Hamamatsu Photonics), the surface of the laminate exposed to UV was irradiated. At this time, ultraviolet rays were irradiated for 30 seconds while applying an alternating magnetic field, and further, ultraviolet rays were irradiated for 1 minute without applying an alternating magnetic field. The cumulative irradiation amount of ultraviolet rays was 9000 mJ / cm ² .
Thereafter, the laminate was removed from the AC magnetic field generator, and the glass plate and the PET resin sheet were peeled off from both sides of the laminate.
In this way, a heat transfer sheet having a structure as shown in FIG. 1 and having a thickness of 0.5 mm according to Example 1 was manufactured.

<Example 2>
[Manufacture of heat transfer sheet]
In Example 1, a heat transfer sheet having a thickness of 0.5 mm according to Example 2 was produced in the same manner as Example 1 except that the amount of steel beads was changed to 90 g.

<Comparative Example 1>
[Manufacture of heat transfer sheet]
In the same manner as in Example 1, a sheet molding material according to Comparative Example 1 was obtained.
And it carried out similarly to Example 1, and obtained the laminated body by which a glass plate, a PET resin sheet, a sheet molding material layer, a PET resin sheet, and a glass plate were laminated | stacked in this order.

The obtained laminate was held at room temperature for 1 minute while applying a DC magnetic field from both sides with two ferrite magnets (380 millitesla) in the thickness direction, and immediately after removing the ferrite magnet on one side One side was irradiated with ultraviolet rays of 9000 mJ / cm ² to perform photocuring treatment.
Thereafter, the ferrite magnet was removed from the other surface, and the glass plate and the PET resin sheet were peeled off from both surfaces of the laminate.
Thus, a heat transfer sheet having a thickness of 0.5 mm according to Comparative Example 1 was manufactured.

<Comparative example 2>
[Manufacture of heat transfer sheet]
In Comparative Example 1, a heat transfer sheet having a thickness of 0.5 mm according to Comparative Example 2 was produced in the same manner as Comparative Example 1 except that the amount of steel beads was changed to 90 g.

<Comparative Example 3>
[Manufacture of heat transfer sheet]
In the same manner as in Example 1, a paste-like sheet molding material according to Comparative Example 3 was obtained.
And it carried out similarly to Example 1, and obtained the laminated body by which a glass plate, a PET resin sheet, a sheet molding material layer, a PET resin sheet, and a glass plate were laminated | stacked in this order.

The obtained laminate was irradiated with 9000 mJ / cm ^{2 of} ultraviolet light without applying a magnetic field, and photocured. Thereafter, the glass plate and the PET resin sheet were peeled off from both sides of the laminate.
Thus, a heat transfer sheet having a thickness of 0.5 mm according to Comparative Example 3 was produced.

<Comparative example 4>
[Manufacture of heat transfer sheet]
In Comparative Example 3, a heat transfer sheet having a thickness of 0.5 mm according to Comparative Example 4 was produced in the same manner as Comparative Example 3 except that the amount of steel beads was changed to 90 g.

<Examples 3 to 7>
[Manufacture of heat transfer sheet]
In Example 1, using any one of composite particles (1) to (5) instead of steel beads, a heat transfer sheet having a thickness of 0.5 mm according to Examples 3 to 7 is manufactured in the same manner as Example 1. did.
Here, the composite particles (1) are used in Example 3, the composite particles (2) are used in Example 4, the composite particles (3) are used in Example 5, and the composite particles (3) are used in Example 6. In Example 7, composite particles (5) were used.

<Example 8>
[Manufacture of heat transfer sheet]
A heat transfer sheet having a thickness of 0.5 mm according to Example 8 was produced in the same manner as in Example 1 except that H-SBR (1) was replaced with urethane oligomer (1) in Example 1.

<Example 9>
[Manufacture of heat transfer sheet]
In Example 1, the sheet molding material according to Example 9 is the same as in Example 1 except that the photopolymerization initiator is replaced with a thermal polymerization initiator (Kaya Ester Co., Ltd., Kayaester O-50E). Got.
And it carried out similarly to Example 1, and obtained the laminated body by which a glass plate, a PET resin sheet, a sheet molding material layer, a PET resin sheet, and a glass plate were laminated | stacked in this order.

The obtained laminate is installed in an AC magnetic field generator (Um-5BF manufactured by Electronic Magnetic Industry Co., Ltd.) as shown in FIG. While applying (100 millitesla, 50 Hz), the temperature was raised to 100 ° C., and a thermosetting treatment was performed under the conditions of a heating temperature of 100 ° C. and a heating time of 2 hours while applying an alternating magnetic field.
Thereafter, the laminate was removed from the AC magnetic field generator, and the glass plate and the PET resin sheet were peeled off from both sides of the laminate.
Thus, a heat transfer sheet having a thickness of 0.5 mm according to Example 9 having a structure as shown in FIG. 1 was produced.

<Example 10>
[Manufacture of heat transfer sheet]
In Example 9, a heat transfer sheet having a thickness of 0.5 mm according to Example 10 was produced in the same manner as Example 9 except that H-SBR (1) was replaced with urethane oligomer (1).

<Evaluation>
The following evaluation was performed about each heat-transfer sheet | seat which concerns on Examples 1-10 and Comparative Examples 1-4. The results are shown in Table 2.

(Thermal conductivity)
On a heat source (hot plate set at 50 ° C.), a glass plate (thickness 1 mm), a heat transfer sheet and a heat sink (copper-plated aluminum plate, Ainex HM-17) are stacked in this order, and a thermography ( The temperature (° C.) of radiant heat of the heat sink was measured using NEC / Avio tvs-500ex).
And the difference (DELTA) T (degreeC) of the said temperature immediately after installation and the said temperature 30 seconds after installation was calculated | required. The larger ΔT (° C.), the better the thermal conductivity.

  From Table 2, it can be seen that the heat transfer sheets according to Examples 1 to 10 are excellent in thermal conductivity.

10 Heat Transfer Sheet 11 Sheet Base 11A Sheet Molding Material Layer 12 Magnetic Particle 20 Mold 21 Upper Mold 22 Lower Mold 23 Spacer 25 AC Magnetic Field Generator 25A Electromagnet 25B Electromagnet MF Magnetic Field 30 Heat Transfer Sheet 31 Sheet Base 32 High Density Portion 33 Low Density portion 40 Upper die 41 Ferromagnetic substrate 42 Ferromagnetic portion 43 Nonmagnetic portion 44 Spacer 45 Lower die 46 Ferromagnetic substrate 47 Ferromagnetic portion 48 Nonmagnetic portion

Claims (9)

A magnetic field application step of applying an alternating magnetic field to a sheet molding material containing a curable composition containing a curable resin and particles containing a magnetic material;
A curing step of curing the sheet molding material applied with an alternating magnetic field by the magnetic field application step;
A method for manufacturing a heat transfer sheet.   The method for manufacturing a heat transfer sheet according to claim 1, wherein the magnetic body is a soft magnetic body.   The method for producing a heat transfer sheet according to claim 1 or 2, wherein the particles are composite particles in which at least a part of the surface of the substrate particles is coated with fine particles having a particle diameter smaller than that of the substrate particles.   The said curable composition is a manufacturing method of the heat-transfer sheet | seat of any one of Claims 1-3 containing a (meth) acrylate monomer and a polymerization initiator further.   The curable resin contains at least one selected from a hydrogenated conjugated diene-aromatic vinyl copolymer having a polymerizable unsaturated group and a urethane liquid oligomer having a polymerizable unsaturated group. The manufacturing method of the heat-transfer sheet | seat of any one of 4.   The method for producing a heat transfer sheet according to claim 5, wherein the polymerizable unsaturated group of the hydrogenated conjugated diene-aromatic vinyl copolymer is a (meth) acryloyl group.   The (meth) acrylate monomer is an alkyl group having 8 to 18 carbon atoms, isobornyl group, cyclohexyl group, dicyclopentanyl group, dicyclopentenyl group, dicyclopentanyloxyethyl group, dicyclopentenyloxyethyl group, nonyl. The manufacturing method of the heat-transfer sheet | seat of any one of Claims 4-6 which has a phenoxy polyethyleneglycol residue or a nonyl phenoxy polypropylene glycol residue.   The heat transfer sheet according to any one of claims 4 to 7, wherein the (meth) acrylate monomer includes a monofunctional (meth) acrylate monomer having a glass transition temperature of -70 ° C or higher and 20 ° C or lower. Production method. It is manufactured by the method for manufacturing a heat transfer sheet according to any one of claims 1 to 8,
A heat transfer sheet in which particles containing a magnetic substance are contained in an oriented state in a sheet substrate made of a curable composition containing a curable resin.