JP2005220220A - Resin composition for heat-releasing material and cured product thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition good in operability and productivity in obtaining it, and capable of producing a heat-releasing material excellent in moldability, flexibility, thermal conductivity and durability, and to provide a cured product of the composition. <P>SOLUTION: The resin composition for heat-releasing material is obtained by compounding (A) an organic compound having two or more hydroxy groups and/or amino groups, (B) an organic compound having two or more isocyanato groups, (C) a thermally conductive filler and (D) an acidic compound. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a resin composition for obtaining a heat dissipation material and a cured product thereof. More specifically, the present invention is excellent in workability and productivity in obtaining a heat dissipation material composition, and has moldability, flexibility, heat, and the like. The present invention relates to a resin composition capable of obtaining an excellent heat dissipation material with good balance in conductivity and durability, and a cured product thereof.

  A heat radiation sheet obtained by molding (curing) a resin composition obtained by blending a heat-resistant filler such as alumina into a resin having flexibility into a sheet shape is, for example, a plasma display (PDP) or an integrated circuit. This is used to prevent the occurrence of functional failures due to the temperature rise of various parts accompanying heat generation.

  These heat-dissipating sheets not only have excellent thermal conductivity, but are used by inserting them between a heat generator and a heat sink such as a metal plate or heat sink, so the contact area between the heat generator and the heat sink is increased. In order to increase the heat conduction efficiency, the sheet is required to have high flexibility.

  Examples of the resin having flexibility include an acrylic urethane resin obtained from an acrylic oligomer having two hydroxyl groups in one molecule and a polyfunctional isocyanate having at least two isocyanate groups in one molecule. Known (for example, Patent Document 1).

  However, when these resins are used, the resulting composition has a high viscosity and poor workability, and the thermal conductivity of the heat-dissipating sheet obtained is low because the high blending of the thermal conductive filler is not possible. It takes a long time to disperse and knead the filler uniformly in the resin, resulting in inferior productivity, and in addition, inferior air defoaming during production of the composition causes bubbles to be generated in the resulting heat dissipation sheet. It seems that there are many problems such as poor formability and heat conduction performance.

  In addition, for example, a resin composition having a urethane bond for paints containing a metal organic compound and an acidic substance as a urethane reaction catalyst is known (see, for example, Patent Document 2). However, Patent Document 2 does not describe a material for heat dissipation, and the addition of an acidic substance only describes the effect as a technique for extending the pot life of a coating composition that is cured by a urethane crosslinking reaction. is there.

JP 2002-30212 A JP 2001-240797 A

  Therefore, in the present invention, in consideration of the above-mentioned problems of the prior art, it is excellent in workability and productivity when obtaining a heat radiating material composition, and excellent in balance in formability, flexibility, thermal conductivity, and durability. An object of the present invention is to provide a heat-dissipating resin composition capable of obtaining a heat-dissipating material and a cured product thereof.

  The present invention that has solved the above problems is an organic compound (A) having two or more hydroxyl groups and / or amino groups, an organic compound (B) having two or more isocyanate groups, a thermally conductive filler (C), and an acidic compound. It is characterized by blending (D).

  The resin composition for heat dissipation material is preferably a (meth) acrylic polymer in which the organic compound (A) has two or more hydroxyl groups.

  In the resin composition for heat dissipation material, the acidic compound (D) is preferably a carboxylic acid having 1 to 8 carbon atoms.

  Furthermore, the present invention includes a heat-radiating cured product obtained by curing the resin composition for heat-dissipating material.

  The resin composition for heat dissipation material and the cured product thereof according to the present invention include an organic compound (A) having two or more hydroxyl groups and / or amino groups, an organic compound (B) having two or more isocyanate groups, and a thermally conductive filler. (C) Since the acidic compound (D) is blended, not only is it excellent in workability and productivity when obtaining a heat radiating material composition, but also moldability, flexibility, thermal conductivity, and durability. We succeeded in obtaining a good cured product efficiently. Therefore, it is used for the purpose of dissipating the heat generated from PDP, electric / electronic parts, etc. by interposing between the heat generating elements, such as PDP, electric / electronic parts, etc. and heat radiators, such as heat sinks, heat radiating fins, metal plates, etc. Can do.

  The resin composition for a heat dissipation material of the present invention (hereinafter simply referred to as a resin composition) includes an organic compound (A) having two or more hydroxyl groups and / or amino groups, and an organic compound (B) having two or more isocyanate groups. The heat conductive filler (C) and the acidic compound (D) are blended as essential components.

  The resin composition of the present invention can cure the resin composition by forming a urethane bond, a urea bond or a burette bond by a crosslinking reaction between (A) and (B). Moreover, it is preferable that at least one of (A) or (B) is a polymer. A polymer here means that whose weight average molecular weight in polystyrene conversion by gel permeation chromatography (GPC) is 1000 or more.

  (A) of the present invention is not particularly limited as long as it is an organic compound having two or more hydroxyl groups and / or amino groups, but is preferably a polymer having a weight average molecular weight of 1,000 or more, and a polymer having two or more hydroxyl groups. Is more preferable.

  Examples of the organic compound having two or more hydroxyl groups include, for example, polyhydric alcohols such as ethylene glycol and propylene glycol, polyether polyols obtained by addition polymerization of polyhydric alcohol and alkylene oxide, and various kinds of hydroxyl groups described below. A polymer etc. are mentioned. These may be used alone or in combination of two or more.

  Examples of the polymer having two or more hydroxyl groups and / or amino groups include (co) polymerization of a monomer having at least one hydroxyl group and amino group and, if necessary, other monomers. Examples thereof include (meth) acrylic polymers, polyether polymers, silicone polymers, polyester polymers, and the like. These polymers may be used alone or in combination of two or more. Among these, a (meth) acrylic polymer is particularly preferable in consideration of the balance of physical properties such as weather resistance, flexibility, and chemical resistance and the cost of the resin composition. The (meth) acrylic polymer is obtained by polymerizing (meth) acrylic acid ester, preferably 70% by mass or more, more preferably, when the polymer is 100% by mass. 80% by mass or more.

  The (meth) acrylic polymer having two or more hydroxyl groups can be obtained, for example, by copolymerizing a conventionally known (meth) acrylic acid ester and a monomer having a hydroxyl group. Especially, since the softness | flexibility of the hardened | cured material of the obtained resin composition improves, (meth) acrylic acid alkyl ester whose carbon number of an alkyl group is 2-18 is used as (meth) acrylic acid ester to be used. It is preferable to use it.

  Specifically, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate , N-hexyl (meth) acrylate, n-amyl (meth) acrylate, i-amyl (meth) acrylate, octyl (meth) acrylate, i-octyl (meth) acrylate, i-myristyl (meth) acrylate, lauryl (meth) ) Acrylate, nonyl (meth) acrylate, i-nonyl (meth) acrylate, i-decyl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, i-stearyl (meth) acrylate, and the like. . These (meth) acrylic acid alkyl esters having 2 to 18 carbon atoms in these alkyl groups may be used alone or in combination of two or more.

  The amount of the alkyl group (meth) acrylic acid alkyl ester having 2 to 18 carbon atoms in these alkyl groups is 50% by mass or more in 100% by mass of the monomer component constituting the (meth) acrylic polymer. It is preferably 70% by mass or more, and most preferably 80% by mass or more.

  Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono ( Examples thereof include, but are not limited to, meth) acrylate, glycerin (meth) acrylate, and hydroxystyrene. Only one type of monomer having a hydroxyl group may be used, or two or more types may be used in combination.

As a polymer having two or more hydroxyl groups, there are a method using a monomer having a hydroxyl group, a method using a polymerization initiator having a hydroxyl group, a method using a chain transfer agent having a hydroxyl group, and the like. A method of copolymerizing a monomer having a hydroxyl group and another monomer, for example, the above-mentioned (meth) acrylic acid alkyl ester is simple and more preferable.
(B) of the present invention is not particularly limited as long as it is an organic compound having two or more isocyanate groups in one molecule. For example, hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), p -Phenylene diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, bis (4-isocyanatocyclohexyl) methane, trimethylolpropane adduct of toluene diisocyanate, toluene diisocyanate Isocyanurate bodies, HDI oligomers, HDI isocyanurate bodies, burette bodies, uretdione bodies, IPDI isocyanurate bodies, monomers with isocyanate groups and (co) polymerization with other monomers as required Isocyanate group-containing (co) polymerization And the like. These may be used alone or in combination of two or more. The isocyanate group in (B) may be blocked with ε-caprolactam, butanone oxime, or phenol.

  Examples of the monomer having an isocyanate group include 2-methacryloyloxyethyl isocyanate and methacryloyl isocyanate, but are not particularly limited. Only one type of isocyanate-containing monomer may be used, or two or more types may be used in combination. Moreover, the monomer which has an isocyanate group may be blocked.

  (B) of this invention has a weight average molecular weight of preferably about 500,000 or less. More preferably, it is liquid at 25 ° C. and has a viscosity of about 8000 mPa · S or less.

  The hydroxyl group and / or amino group in the polymer having two or more hydroxyl groups and / or amino groups may be contained in an amount of about 0.5 mol% as a lower limit in all monomer components constituting the polymer. Preferably, about 1.0 mol% is more preferable, and about 2 mol% is most preferable. The upper limit is preferably about 10 mol%, more preferably about 8 mol%, and most preferably about 6 mol%. By setting the above lower limit value and upper limit value, the flexibility of the cured product of the resin composition tends to increase.

  The glass transition point of the polymer having two or more hydroxyl groups and / or amino groups is preferably about 0 ° C. or lower, more preferably about −20 ° C. or lower, and further preferably about −40 ° C. or lower. As the glass transition point is lower, the flexibility of the cured product of the resin composition tends to increase. The glass transition point can be measured by a conventional method using a differential scanning calorimeter.

  The molecular weight of the polymer having two or more hydroxyl groups and / or amino groups is preferably about 1000 as the lower limit, more preferably about 5000, as the weight average molecular weight in terms of polystyrene by gel permeation chromatography (GPC). About 10,000 is most preferable. The upper limit is preferably about 1,000,000, more preferably about 800,000, and most preferably about 600,000. By setting the above lower limit value and upper limit value, the resin composition tends to be cured in a short time, and the viscosity of the resin composition tends to be low and the workability tends to be good.

  (B) of the present invention is preferably used in an amount of about 0.1 equivalent as the lower limit with respect to the functional group of (A) in the resin composition, that is, the total of hydroxyl groups and / or amino groups, About 0.5 equivalent is more preferable, and about 0.7 equivalent is most preferable. The upper limit is preferably about 2.0 equivalents, more preferably about 1.8 equivalents, and most preferably about 1.5 molar equivalents. By setting the above lower limit value and upper limit value, the flexibility of the cured product of the resin composition tends to increase.

The resin composition of the present invention contains a thermally conductive filler (C) (hereinafter simply referred to as filler) in order to increase the thermal conductivity of the resulting cured product. Specifically, a filler having a thermal conductivity of 20 W / m · K or more is preferable, and examples thereof include aluminum oxide, magnesium oxide, zinc oxide, silicon carbide, aluminum nitride, boron nitride, and silicon nitride. Aluminum oxide is preferable from the balance between the obtained heat dissipation performance and cost. Moreover, when using these, you may use 2 or more types together. The thermal conductivity of the filler to be used can be measured using the sintered product, using a thermal conductivity measuring device part number TPA-501 by the hot disk method manufactured by Kyoto Electronics Industry Co., Ltd.
The filler is preferably contained in an amount of about 30 to 95% by mass in 100% by mass of the resin composition, more preferably about 40 to 95% by mass, and further about 50 to 95% by mass. preferable. These fillers, as the proportion in the resin composition is large, the thermal conductivity of the resulting cured product is increased and the heat dissipation performance is improved, but on the other hand, the flexibility of the resulting cured product is reduced, for example, The content is preferably adjusted according to the required thermal conductivity and hardness.

  Since the filler is required to be quickly and uniformly dispersed in the resin composition and to increase the content in the resin composition as required, surface treatment may be performed by silane treatment or the like. Further, examples of the shape of the filler include a spherical shape, a fibrous shape, a scale shape, a planar shape, a crushed shape, and an indefinite shape, but are not particularly limited.

  The resin composition of the present invention preferably contains an organometallic compound (hereinafter simply referred to as a metal compound) in order to promote the crosslinking reaction between (A) and (B) of the resin composition. In the periodic table of chemical handbook application edition 3rd edition (published by the Chemical Society of Japan, published by Maruzen Co., Ltd.), it is a metal compound having transition metal elements belonging to groups 3A-7A, 8, 1B and metal elements belonging to 2B-6B. It may be sufficient, and is appropriately selected according to the reaction time, reaction temperature, composition of the resin composition, and the like. Among these, tin, zinc and lead are preferable, and tin is more preferable. These metal compounds may be used alone or in combination of two or more.

  Examples of tin metal compounds include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin di (2 ethylhexanoate), dihexyltin diacetate, dioctyltin dilaurate, and dimethyltin bis (isooctylthioglycolate) salt. And tin octylate.

  Examples of the zinc metal compound include zinc naphthenate, 2-ethylhexyl zinc, and the like.

  Examples of the lead metal compound include lead stearate, lead naphthenate, and 2-ethylhexyl lead.

  The metal compound is preferably contained in the resin composition in an amount of about 0.001 to 3 parts by mass, more preferably about 0.003 to 2 parts by mass with respect to 100 parts by mass of (A). More preferably, about 005 to 1 part by mass is contained. By making it into the above-mentioned range, the effect of accelerating the crosslinking reaction between (A) and (B) in the resin composition is high (catalytic effect) without reducing the physical properties of the cured product of the resulting resin composition. Tend to be high).

  Moreover, you may use crosslinking accelerators other than organometallic compounds, such as tertiary amine, in order to accelerate | stimulate a crosslinking reaction as needed.

  In the resin composition of the present invention, for example, the effect of improving the productivity by enabling uniform dispersion of the filler quickly, the viscosity of the resin composition can be lowered, the filler can be highly blended, and the obtained cured product The acidic compound (D) is included for the purpose of imparting the effect of improving the heat dissipation (heat conduction) performance and the easy defoaming performance capable of easily removing the air contained during the production of the resin composition. Thus, an acidic compound plays the role which extracts the effect of the filler essential as a heat dissipation material to the maximum, for example, solves the subject peculiar to said heat dissipation material.

  The acidic compound (D) is not particularly limited as long as it has a PKa (acid dissociation constant) defined by Chemical Handbook II (Edited by The Chemical Society of Japan, published by Maruzen Co., Ltd.) and has an acidity of 1.0 or more. In order to sufficiently exhibit the effects of the present invention, an organic acidic compound is preferable, and a carboxylic acid is more preferable. In addition, because of the concern about corrosion of electrical and electronic parts caused by acidic compounds in the cured product of the resin composition, the acidic compound used is not used in order to prevent the acidic compound from remaining in the cured product after obtaining the cured product. The compound is more preferably a carboxylic acid having a boiling point of 250 ° C. or less at normal pressure, and particularly preferably a carboxylic acid having 1 to 8 carbon atoms. In addition, these include substituted products, and only one type may be used, or two or more types may be used in combination.

  Examples of the carboxylic acid having a boiling point of 250 ° C. or lower and a total carbon number of 1 to 8 include formic acid, acetic acid, propionic acid, butanoic acid, valeric acid, hexanoic acid, 2-ethylhexanoic acid and the like. When the curing temperature is 130 ° C. or lower, it is preferable to use a carboxylic acid having a boiling point of 170 ° C. or lower at normal pressure of the acidic substance to be used.

  The acidic compound (D) is preferably contained in the resin composition in an amount of about 0.005 parts by mass, more preferably about 0.01 parts by mass with respect to 100 parts by mass of (A). About 0.03 parts by mass is most preferable. The upper limit is preferably about 5 parts by mass, more preferably about 3 parts by mass, and most preferably about 2 parts by mass. By setting the above lower limit value and upper limit value, for example, it is possible to easily remove the tendency to reduce the viscosity of the resin composition and enable high blending of fillers and the air contained in the production of the resin composition. There is a tendency.

  It is preferable to add a liquid oily substance to the resin composition of the present invention as necessary. By using a liquid oily substance, it is possible to give more flexibility to the cured product of the resin composition.

  The liquid oily substance that can be used in the present invention is only required to be liquid and oily (having a property not to be mixed with water) under normal pressure and 25 ° C conditions. For example, higher (5 to 18 carbon atoms) alcohols, esters, ethers, chlorinated paraffin, process oil, fatty oil, phthalic acid plasticizer, trimellitic acid plasticizer, adipic acid plasticizer, polyester Plasticizer, epoxy plasticizer, phosphate ester plasticizer, rubber plasticizer, aliphatic monobasic acid plasticizer, aliphatic dibasic acid plasticizer, liquid rubber, synthetic rubber, etc. Various plasticizers are preferable, and when these liquid oily substances are used, two or more kinds may be used in combination.

  Further, the liquid oily substance has high heat resistance, that is, the weight loss when kept at 100 ° C. for 168 hours is preferably about 10% by mass or less, more preferably about 8% by mass or less, and more preferably 5% by mass or less. Most preferred is. When a liquid oily substance having a small weight loss is used, the flexibility of the cured product of the obtained resin composition tends to be maintained over a long period of time. The weight loss of the liquid oily substance used is determined by measuring the weight loss when 3 g of the liquid oily substance is put in an aluminum watch glass having a diameter of 5 cm and kept in an oven heated to 100 ° C. for 168 hours. Can be sought.

  The liquid oily substance is preferably added in an amount of about 5 to 400 parts by mass when (A) in the resin composition is 100 parts by mass. When used within the above range, the cured product of the obtained resin composition does not have a bleed of a liquid oily substance and tends to impart flexibility.

  When (A) or (B) of the present invention is a polymer, it can be obtained by polymerizing by a known polymerization method such as bulk polymerization, solution polymerization or emulsion polymerization using a known polymerization initiator. . In particular, in the case of a resin composition using a liquid oily substance, if a polymerization method in which polymerization is performed in the liquid oily substance is employed, a mixture of the polymer and the liquid oily substance can be obtained in one step, which is preferable. Of course, the mixture may be adjusted by adding a monomer or an additive separately.

  The resin composition of the present invention can be obtained using a conventionally known kneader. For example, a continuous kneader such as a mixer, a roll mill, a Banbury mixer, a kneader, a pressure type kneader, or a twin-screw kneader may be used, but it is not particularly limited. If necessary, the kneading may be performed while reducing the pressure in the apparatus to remove air contained in the composition, or while heating or pressurizing. The resin composition of the present invention can be used as it is, or can be used as a cured product obtained by, for example, a molding method described later after kneading.

  The cured product of the resin composition of the present invention refers to a state in which the resin composition does not have fluidity due to the crosslinking reaction of (A) and (B) in the resin composition.

  The resin composition of the present invention is obtained when the cured product of the resin composition is kept in an oven heated to 100 ° C. for 168 hours in order to stably express the flexibility of the obtained cured product over a long period of time. The weight loss is preferably about 5% by mass or less, more preferably about 3% by mass or less, and most preferably about 2% by mass or less. If the weight loss is small, there is a tendency to maintain the long-term flexibility required as a heat dissipation material.

  A heat-radiating cured product can be obtained by curing the resin composition of the present invention. Further, the resin composition can be cured into a desired shape such as a sheet shape, a tape shape, a tube shape, or a roll shape, and the shape, the curing method, and the curing apparatus are not particularly limited. For example, the heat-dissipating cured product may be obtained by charging the resin composition into an injection mold or batch mold and curing it to a desired shape, and curing it into a sheet by a method such as an extruder or casting. You may get it. The curing temperature is preferably 170 ° C. or lower, and more preferably 150 ° C. or lower.

  In order to improve the strength and handleability of the obtained resin composition, the heat-radiating cured product of the present invention may be impregnated or adhered to the surface of the resin composition with inorganic fibers or organic fibers, various films, and the like.

  The resin composition of the present invention is conventionally known in the field of molding materials, for example, reinforcing fibers, inorganic fillers, organic fillers, polymerization initiators, polymerization inhibitors, low shrinkage agents, mold release agents, thickening agents. Agent, defoaming agent, wetting and dispersing agent, thixotropic agent, UV absorber, UV stabilizer, antioxidant, phosphorus flame retardant, halogen flame retardant, inorganic such as aluminum hydroxide and magnesium hydroxide Additives such as flame retardants, coupling agents, pigments, dyes, magnetic substances, antistatic agents, electromagnetic wave absorbers, paste oils, paraffin wax, microcrystalline wax, higher fatty oils, thermal softeners, etc. Any of them can be used as long as the object of the invention is not impaired.

  As an indication of the amount added, an amount that does not contradict the purpose of the present invention is preferable, and specifically, it is desirable that the total amount of additives is 1000 parts by mass or less with respect to 100 parts by mass of the resin composition. A more preferable upper limit of the addition amount is 900 parts by mass, and a more preferable upper limit is 800 parts by mass.

  The present invention will be described in further detail with reference to the following examples. However, the following examples are not intended to limit the present invention, and all modifications that are made without departing from the spirit of the preceding and following description are all included in the technical scope of the present invention. The In Examples and Comparative Examples, “parts” means “parts by mass” and “%” means “mass%” unless otherwise specified.

Synthesis example 1
In a vessel equipped with a thermometer, stirrer, gas inlet tube, reflux condenser, and dropping funnel, 39.22 parts of 2-ethylhexyl acrylate, 0.78 parts of 2-hydroxyethyl acrylate (hydroxyl group in all polymerizable monomers) 3 parts by weight monomer), 50 parts of trimellitic acid ester plasticizer as a liquid oily substance (manufactured by Asahi Denka Kogyo; trade name “Adekasizer C880”), α-methylstyrene as a chain transfer agent 0.15 parts of dimer was charged and the inside of the container was replaced with nitrogen gas.

  The temperature was raised to 75 ° C., 0.1 part of dimethyl 2,2′-azobis (2-methylpropionate) as a polymerization initiator, and 10 parts of trimellitic ester plasticizer (manufactured by Asahi Denka Kogyo Co., Ltd .; product) A mixture of the name “Adeka Sizer C880”) was charged into a dropping funnel and dropped over 1.5 hours. Further, 0.03 part of dimethyl 2,2′-azobis (2-methylpropionate) was added as a polymerization initiator, and the temperature was raised to 90 ° C. for polymerization for 2 hours.

  Before completion of the polymerization, 0.05 part of dibutyltin dilaurate was added as an organometallic compound, air was blown in, the system was cooled, and the polymerization was terminated to obtain a (meth) acrylic resin (hereinafter referred to as “resin A”). The residual 2-ethylhexyl acrylate as determined by gas chromatography (GC) was 0.1%, and the polymer having 3 mol% hydroxyl group in Resin A was 39.9%. The viscosity of the obtained resin A at 25 ° C. was 6100 mPa · S. Regarding the molecular weight of the polymer measured using GPC (gel permeation chromatography), the weight average molecular weight Mw was 36,000 and the number average molecular weight Mn was 91,000. Moreover, the glass transition temperature of the polymer measured by a conventional method using a differential scanning calorimeter was −60 ° C.

  In addition, the weight loss when the trimellitic acid ester plasticizer used as a liquid oily substance (Asahi Denka Kogyo Co., Ltd .; trade name “Adeka Sizer C880”) is kept at 168 hours in an oven heated to 168 hours is 0.2%.

Example 1
100 parts of resin A, 0.1 part of defoaming agent (produced by Big Chemie; trade name “A-515”), 0.57 part of hexamethylene diisocyanate as an organic compound having two or more isocyanate groups in one molecule ( The amount of hydroxyl group in the polymer and 1.0 equivalent amount of isocyanate), 0.25 parts of acetic acid (boiling point 119 ° C.) as an acidic compound, and aluminum oxide 200 having a thermal conductivity of 30 W / m · k as a thermally conductive filler Part (manufactured by Showa Denko KK; product number AS-10) was uniformly kneaded with a three-one motor (product number 600G) manufactured by Shinto Kagaku Co., Ltd. at a rotational speed of 300 rpm for 5 minutes. The viscosity, pot life at 25 ° C., and defoaming property of the resin composition obtained by kneading were measured under the following conditions. The results are shown in Table 1.

  Next, the obtained resin composition was subjected to defoaming conditions shown below for 2 minutes and 10 minutes to a bar coater set to have a thickness of 1 mm on a PET film subjected to a release treatment. And applied. Next, these coated products were heated at 100 ° C. for 2 hours to cause the polymer having a hydroxyl group in the composition to react with hexamethylene diisocyanate, thereby obtaining a sheet-like cured product of the resin composition. . The formability of the sheet obtained at this time was evaluated under the conditions shown below, and the results are shown in Table 1. Further, for the sheet obtained by setting the defoaming time to 10 minutes, the initial thermal conductivity, the initial hardness, the heat resistance, and the durability of the sheet were evaluated according to the following criteria. The results are shown in Table 1.

Example 2
A resin composition and a sheet-like cured product of the resin composition were obtained in the same manner as in Example 1, except that the acidic compound was changed from acetic acid to 0.25 part of propionic acid (boiling point 141 ° C.). Moreover, it evaluated similarly to Example 1, and showed the result in Table 1.

Example 3
In Example 1, a resin composition and a sheet-like cured product of the resin composition were obtained in the same manner except that the heat conductive filler was changed from 200 parts to 300 parts. Moreover, it evaluated similarly to Example 1, and showed the result in Table 1.

Comparative Example 1
In Example 1, a resin composition and a sheet-like cured product of the resin composition were obtained in the same manner except that no acidic compound was used. Moreover, it evaluated similarly to Example 1, and showed the result in Table 1. It was confirmed that the obtained resin composition had a high viscosity and poor workability as compared to any of Examples, it took a long time to completely degas, and the pot life was short. Therefore, compared with any Example, it resulted in inferior productivity and the cost increase.

  Moreover, the hardened | cured material which made the defoaming time 2 minutes resulted in inferior moldability. This is considered to be an influence of bubbles present in the cured product.

Comparative Example 2
In Example 1, a resin composition and a sheet-like cured product of the resin composition were obtained in the same manner except that no acidic compound was used and the heat conductive filler was changed from 200 parts to 300 parts. Moreover, it evaluated similarly to Example 1, and showed the result in Table 1. The obtained resin composition was found to be poorly dispersed in the filler, and had a higher viscosity than the examples (exceeding the upper limit of the instrument and could not be measured), and even when the defoaming time was 10 minutes, Existence was recognized. Moreover, it was recognized that a pot life is short compared with any Example. Therefore, compared with any Example, it resulted in inferior productivity and the cost increase.

It was also confirmed that the cured product was inferior in moldability and thermal conductivity was low. This is considered to be an influence of bubbles present in the cured product.
Below, the measuring method and evaluation criteria in each evaluation are shown.

[viscosity]
The viscosity at 25 ° C. of the obtained resin composition was measured using a B-type viscometer under the conditions of rotor N0.4 and rotation speed 6 rpm. If the viscosity is low, for example, not only the workability is excellent, but also the effect of improving the heat dissipation (heat conduction) performance of the cured product obtained by enabling high filling of the heat conductive filler, and the production of the resin composition It is possible to impart easy defoaming performance that can easily remove air contained at times.

[Pot life at 25 ° C]
The obtained resin composition was stored in a water bath adjusted to 25 ° C., viscosity was measured over time under the same conditions as in the viscosity measurement, and an increase in viscosity of 20% or more was confirmed from the initial viscosity value. Time was measured as pot life (pot life). However, when the increase in viscosity was less than 10% after 8 hours, the evaluation was made 8 hours or more. For example, if the pot life is long, a large amount of production is possible at one time, which is excellent in cost.

[Defoaming]
The obtained resin composition is statically placed in a vacuum desiccator whose vacuum degree is set to 0.09 MPa, and is included in the resin composition when defoaming is performed for 2 minutes, 5 minutes, and 10 minutes, respectively. The presence of bubbles was visually observed. The case where bubbles were not confirmed by visual observation was judged as “good”, and the case where even small amounts were confirmed was judged as “poor”. For example, if no bubbles are confirmed in a short defoaming operation, the productivity is excellent.

[Formability of sheet]
The obtained sheet-like cured product was visually observed and evaluated according to the following criteria.
○: There is no unevenness or bubbles on the sheet surface.
There is no stickiness on the sheet.
There is no separation or sedimentation of the thermally conductive filler and it is uniform.
As mentioned above, when all the phenomena were satisfied, it evaluated as (circle).
X1: When unevenness | corrugation and foam existed on the sheet | seat surface, it evaluated as x1.
X2: Liquid oily substance separated on the sheet surface.
Separation and sedimentation of the thermally conductive filler were observed, and a non-uniform sheet was obtained.
As mentioned above, when any phenomenon was confirmed, it evaluated as x2.

[Initial thermal conductivity of sheet]
It was measured with a rapid thermal conductivity meter, product number QTM-500, manufactured by Kyoto Electronics Industry. As the measurement sample, a sheet-like cured product laminated so as to have a thickness of 10 mm is used. The measurement is performed at 25 ° C.

  The following evaluation was further performed on the sheet obtained by setting the defoaming time to 10 minutes.

[Initial hardness of sheet]
According to JIS K7312, it measured using the Asker rubber hardness meter C type | mold by Kobunshi Keiki Co., Ltd. The smaller the obtained numerical value, the more flexible. For the measurement value, a hardness meter is placed on the center of the measurement sample, and the maximum indicated value immediately after that is adopted. The measurement is performed at 25 ° C.
As the measurement sample, a sheet-like cured product laminated so as to have a thickness of 10 mm is used.

[Heat-resistant]
The obtained sheet-like cured product is held in an oven set at 100 ° C. for 168 hours, and then the weight loss, hardness, and thermal conductivity of the sheet are measured.
The weight loss is obtained from (weight before measurement−weight after measurement) / weight before measurement × 100 = weight loss (%). The hardness is measured according to JIS K7312 using an Asker rubber hardness meter C type manufactured by Kobunshi Keiki Co., Ltd. The smaller the obtained numerical value, the more flexible, and the smaller the difference in hardness before and after the heat resistance test (initial hardness of the sheet), the longer the flexibility. In addition, the sample of hardness measurement uses what laminated | stacked the sheet-like hardened | cured material so that it might become thickness of 10 mm. The thermal conductivity was measured by a rapid thermal conductivity meter product number QTM-500 manufactured by Kyoto Electronics Industry. As the sample, a sheet-like cured product laminated so as to have a thickness of 10 mm is used. The measurement is performed at 25 ° C.

[durability]
A hardness difference (Δ hardness) between the initial hardness of the sheet and the sheet hardness after the heat resistance test is obtained.
If this value is small, the flexibility of the sheet can be maintained over a long period of time. Therefore, when the sheet is interposed between the heating element and the heat dissipation element, the contact area between them can be maintained over a long period of time, and as a result, the heat dissipation from the heating element The heat conduction efficiency to the body does not decrease, and stable heat radiation characteristics can be obtained (durability) for a long period of time.

The abbreviations used in Table 1 have the following meanings.
HDI: Hexamethylene diisocyanate A-515: manufactured by Big Chemie Co., Ltd. Defoamer; trade name “A-515”
Δ Hardness: Difference in hardness between the initial sheet hardness value and the sheet hardness value after the heat resistance test

As is apparent from Table 1, the present invention example is excellent in workability and productivity in obtaining a heat radiating material composition, and is excellent in moldability, flexibility, thermal conductivity, and durability. A cured product of the composition for use can be obtained efficiently. On the other hand, all the comparative examples are inferior in workability and productivity in obtaining the heat radiating material composition as compared with the examples, and the obtained cured product is also inferior in moldability and thermal conductivity. It became.

Claims (4)

  An organic compound (A) having two or more hydroxyl groups and / or amino groups, an organic compound (B) having two or more isocyanate groups, a thermally conductive filler (C), and an acidic compound (D) A resin composition for a heat dissipation material.   The resin composition for a heat dissipation material according to claim 1, wherein the organic compound (A) is a (meth) acrylic polymer having two or more hydroxyl groups.   The resin composition for a heat dissipation material according to claim 1, wherein the acidic compound (D) is a carboxylic acid having 1 to 8 carbon atoms. The heat-radiation hardened | cured material obtained by hardening the resin composition for heat-radiating materials of Claims 1-3.