JP2022072896A - Polyurethane foam, and production method thereof - Google Patents

Abstract

To provide a production method of inexpensive polyurethane foam excellent in thermal conductivity and moldability, the method requiring no costly magnetic field generator or the like and suppressing poor agitation and extended agitation time even when the blend amount of a filler of thermal conductivity is increased.SOLUTION: Polyurethane foam is produced from a raw material containing a polyol, an isocyanate, a catalyst, a filler of thermal conductivity, and a diluent. The blend amount of the filler of thermal conductivity is 50-400 pts.wt. to 100 pts.wt. of the polyol. The diluent is a physical foaming agent of a boiling point of 15-60°C.SELECTED DRAWING: Figure 1

Description

The present invention relates to a polyurethane foam having good thermal conductivity and a method for producing the same.

Conventionally, polyurethane foam has been used as a vibration damping material and a soundproofing material in OA equipment, electric appliances, and the like. For example, in a hard disk drive of a PC or an electric motor of an electric vehicle, polyurethane foam is arranged inside or outside the housing to improve vibration damping and soundproofing. Further, since a hard disk drive or an electric motor may become hot due to heat generation during operation, polyurethane foam is required to have good thermal conductivity from the viewpoint of heat dissipation to the outside.

As a method of imparting thermal conductivity to polyurethane foam, a thermally conductive filler such as graphite is blended with a polyurethane foam raw material. However, if a large amount of the heat conductive filler is added to the polyurethane foam raw material in order to improve the heat conductivity, the viscosity of the polyurethane foam raw material increases remarkably, making uniform stirring and mixing difficult, and good polyurethane foam cannot be obtained. There is a problem that the stirring time becomes too long and the workability becomes inferior.

In addition, a urethane foam resin raw material containing magnetic particles adhered to the surface of the heat conductive particles by a binder is charged (injected) into a foamed cavity, and a magnetic field is applied so that the magnetic flux density in the cavity becomes substantially uniform. However, there is a method of producing a polyurethane foam by foam molding (Patent Document 1).

Japanese Patent No. 5829279

However, the method of foam molding while applying a magnetic field has a problem that the cost increases for a device or the like that generates a magnetic field.
The present invention has been made in view of the above points, and an object of the present invention is to provide a polyurethane foam having good thermal conductivity without the need for a costly magnetic field generator or the like.

The first means is a polyurethane foam obtained from a polyurethane foam raw material containing a polyol, an isocyanate, a catalyst, a heat conductive filler, and a diluent, and the blending amount of the heat conductive filler is 100 parts by weight of the polyol. It is 50 to 400 parts by weight, and the diluent is a physical foaming agent.

The second means is a method for producing a polyurethane foam in which a polyurethane foam raw material containing a polyol, an isocyanate, a catalyst, a heat conductive filler, and a diluent is filled in a mold and foamed. It is 50 to 400 parts by weight with respect to 100 parts by weight of the polyol, and the diluent is a physical foaming agent.

Since the present invention contains a physical foaming agent as a diluent in the polyurethane foam raw material, it is possible to suppress an increase in viscosity during mixing and stirring of the polyurethane foam raw material even if the amount of the heat conductive filler is larger than before. It is possible to prevent poor stirring and long stirring time. As a result, a polyurethane foam having good foaming and high thermal conductivity can be obtained with good workability. Further, since the polyurethane foam gradually generates heat due to the heat of reaction during foaming and the internal temperature of the polyurethane foam reaches 60 ° C. or higher, the diluent composed of the physical foaming agent volatilizes, and the adverse effect of the residual diluent can be prevented. ..

It is a table which shows the result of the compounding of a polyurethane foam raw material in an Example, agitation property, thermal conductivity and the like. It is a table which shows the result of the compounding of a polyurethane foam raw material in a comparative example, agitation property, thermal conductivity and the like. It is a table which shows the viscosity measurement result with respect to some Example and comparative example. It is a graph which shows the result of FIG.

Hereinafter, embodiments of the polyurethane foam of the present invention will be described. The polyurethane foam of the present invention is obtained from a polyurethane foam raw material containing a polyol, an isocyanate, a catalyst, a thermally conductive filler, and a diluent.

As the polyol, a polyol for polyurethane foam can be used, and for example, any of a polyether polyol, a polyester polyol, a polyether ester polyol, and the like may be used, and one or more of them may be used.

Examples of the polyether polyol include polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, neopentyl glycol, glycerin, pentaerythritol, trimethylolpropane, sorbitol, and shoe cloth, and ethylene oxide (EO). ), Polyether polyols to which alkylene oxides such as propylene oxide (PO) are added.

The polyester polyol is, for example, polycondensed from an aliphatic carboxylic acid such as malonic acid, succinic acid or adipic acid, an aromatic carboxylic acid such as phthalic acid, and an aliphatic glycol such as ethylene glycol, diethylene glycol or propylene glycol. The polyester polyol obtained in the above can be mentioned.
Further, examples of the polyether ester polyol include those obtained by reacting the polyether polyol with a polybasic acid to form a polyester, or those having both segments of polyether and polyester in one molecule.

As for the polyol, it is preferable to use one or more polyols having a hydroxyl value (OHV) of 10 to 280 mgKOH / g, a number of functional groups of 2 to 4, and a number average molecular weight of 800 to 10000 (more preferably 2000 to 7000). ..

As the isocyanate, an aliphatic or aromatic polyisocyanate having two or more isocyanate groups, a mixture thereof, and a modified polyisocyanate obtained by modifying them can be used. Examples of the aliphatic polyisocyanate include hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexamethane diisocyanate and the like, and examples of the aromatic polyisocyanate include toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), naphthalenediisocyanate and xiri Examples thereof include range isocyanate and polypeptide MDI (crude MDI). In addition, other prepolymers can also be used.

The isocyanate index (INDEX) is preferably 75 to 120. The isocyanate index is calculated by [(isocyanate equivalent in polyurethane foam raw material / equivalent of active hydrogen in polyurethane foam raw material) × 100].

As the catalyst, a catalyst known for polyurethane foam can be used. For example, amine catalysts such as triethylamine, triethylenediamine, diethanolamine, dimethylaminomorpholine, N-ethylmorpholine, tetramethylguanidine, tin catalysts such as stanus octate and dibutyltin dilaurate, phenylmercuric propionate or lead octenoate. And other metal catalysts (also referred to as organic metal catalysts). The amount of the catalyst is preferably about 0.5 to 3 parts by weight with respect to 100 parts by weight of the polyol.

The foaming agent is selected from the group consisting of chemical foaming agents and physical foaming agents. The chemical foaming agent is a substance that generates a gas for forming bubbles based on a chemical reaction in foam molding, and the physical foaming agent forms bubbles in foam molding due to a change in the state of the substance. A liquid (liquid) chemical foaming agent or physical foaming agent is preferable from the viewpoint of raw material mixing and foamability, and a liquid (liquid) chemical foaming agent or physical foaming agent at 10 ° C. is particularly preferable. The chemical foaming agent preferably contains water from the viewpoint of mixing raw materials. The amount of the foaming agent (water) is preferably 0.5 to 1.5 parts by weight with respect to 100 parts by weight of the polyol. When the amount of the foaming agent (water) is less than 0.5 parts by weight, the mixing and reactivity of the raw materials are deteriorated, and molding defects are likely to occur. On the other hand, if it exceeds 1.5 parts by weight, the foaming gas increases and cracks are likely to occur inside the molded product, resulting in a decrease in thermal conductivity.

Examples of the thermally conductive filler include expanded graphite, expanded graphite, scaly graphite, alumina, magnesium oxide, silicon (metal silicon), boron nitride and the like. Here, the expanded graphite can be obtained, for example, by chemically treating graphite such as scaly graphite with sulfuric acid or the like, heat-treating it to expand it, and then refining it. The heat conductive filler is not limited to one type, and a plurality of types may be used in combination.

The blending amount of the thermally conductive filler is preferably 50 to 400 parts by weight, more preferably 100 to 350 parts by weight, and more preferably 200 to 300 parts by weight with respect to 100 parts by weight of the polyol. If the amount of the heat conductive filler is too small, the heat conductivity of the polyurethane foam will be low, and if it is too large, the foaming of the polyurethane foam will be poor.

The diluent consists of a physical foaming agent. The physical foaming agent preferably has a boiling point of 10 to 80 ° C, preferably 15 to 60 ° C. Since the diluent has a boiling point of 10 to 80 ° C., it is liquid during mixing and stirring of the polyurethane foam raw material, and even if the blending amount of the heat conductive filler is increased, the increase in viscosity of the polyurethane foam raw material during mixing and stirring is suppressed. It is possible to prevent poor stirring and long stirring time. As a result, a polyurethane foam having good foaming and high thermal conductivity can be obtained with good workability.

Further, as the diluent, the diluent is volatilized by the heat generated during the foaming of the polyurethane foam, and the adverse effect of the residual diluent on the polyurethane foam can be prevented.

Examples of the diluent composed of a physical foaming agent having a boiling point of 10 to 80 ° C. include hydrocarbon compounds such as pentane, chlorofluorocarbon compounds such as hydrofluoroolefin (HFO) and perfluorocarbon (PFC), and the like. The diluent is not limited to one type, and two or more types may be used.
The amount of the diluent is preferably 10 to 30 parts by weight with respect to 100 parts by weight of the polyol.

The polyurethane foam raw material preferably contains a defoaming agent. The defoaming agent has an action of destroying foam when the polyurethane foam is foamed. By blending the defoaming agent with the polyurethane foam raw material, cracks in the polyurethane foam and cracks in the polyurethane foam can be caused, especially in the region where the density of the polyurethane foam molded body is high (density is 1.1 g / cm ³ or more to 1.6 g / cm ³ ). It is possible to suppress the generation of burrs during molding, and it becomes possible to satisfactorily produce a polyurethane foam having excellent thermal conductivity.

Examples of the type of defoaming agent include hydrocarbon-based, ester-based, and silicone-based, and two or more of them may be used.
Examples of the hydrocarbon-based defoaming agent include oils such as polybutene. Examples of the ester-based defoaming agent include dimer acid diester and the like. Examples of the silicone-based defoaming agent include cyclopentasiloxane.

When the defoaming agent is blended, the blending amount is preferably 1 to 15 parts by weight with respect to 100 parts by weight of the polyol. If the amount of the defoaming agent is too large, it becomes difficult to foam the polyurethane foam well.

Other auxiliaries may be added to the polyurethane foam raw material. As an auxiliary agent, for example, a foam stabilizer, a colorant, a flame retardant and the like can be mentioned.
As the foam stabilizer, those known for polyurethane foam can be used. For example, a silicone-based defoaming agent, a fluorine-based defoaming agent, and a known surfactant can be mentioned. It is preferable to add the foam stabilizer in terms of uniformly mixing the polyurethane foam raw materials.
As the colorant, a carbon pigment or the like can be used depending on the intended use of the polyurethane foam.
Examples of the flame retardant include powder flame retardants such as phosphorus and ammonium polyphosphate, and liquid flame retardants such as phosphoric acid ester flame retardants, and either one or both may be used in combination.

The polyurethane foam of the present invention preferably has a density (JIS K 7222) of about 0.70 to 1.65 g / cm ³ .
Further, the polyurethane foam of the present invention preferably has a thermal conductivity (measured using a measuring instrument QTM500 manufactured by Kyoto Denshi Kogyo Co., Ltd., which measures the thermal conductivity using the hot wire method) of 0.5 W / m · K or more.

The polyurethane foam of the present invention is suitable for applications such as motors for electric vehicles and hybrid vehicles, inverters, DC converters, heat dissipation members for batteries, and vibration damping members.

Polyurethane foam is manufactured by a mold foam molding method in which a polyurethane foam raw material is stirred and mixed, charged (injected) into a mold, foamed in the mold, the mold is opened, and a molded product is taken out. The cavity of the mold has a product shape according to the application of polyurethane foam. Further, the mold is provided with a slit for venting gas on the contact surface between the upper mold and the lower mold so that the gas generated at the time of foaming the polyurethane foam can be discharged.

Using the following raw materials, polyurethane foams of each example and each comparative example were produced by a mold foam molding method. Specifically, the polyurethane foam raw material is prepared by the formulation shown in FIG. 1 or 2, and the polyurethane foam raw material after stirring and mixing is charged into the cavity of the lower mold with the amount of the mold charged as shown in FIG. 1 or FIG. The mold was covered and closed, and after 8 minutes, the mold was opened to obtain polyurethane foam. The cavity of the mold is 100 × 150 × t10 mm, and a slit for venting gas is provided on the contact surface between the upper mold and the lower mold.

The raw material temperature during mixing and stirring of the polyurethane foam raw material was 23 ° C. Similarly, the temperature was set to 23 ° C. for the comparative example in which the diluent was not added.
The mold temperature was set to 64 ° C. or higher, which was equal to or higher than the boiling point of the diluent.

・ Polyester polyol, Mw5000, hydroxyl value 34 mgKOH / g, number of functional groups 3, product number; Sanniks FA-703, Sanyo Kasei Kogyo Co., Ltd. ・ Catalyst: product number; DABCO 33LSI, EVONIK ・ Thermal conductive filler A: expansion Graphite, average particle diameter 300 μm, product number; SYZR502FP, Sanyo Trading Co., Ltd. ・ Thermal conductive filler B: metallic silicon, average particle diameter 20 μm, product number; # 200, Kinsei Matek Co., Ltd.

・ Foam regulator: Silicone foam stabilizer, product number: B8738LF2, EVONIK ・ Foam breaker: Dimer acid diester, product number; ADDITIVE T, Hitachi Kasei Co., Ltd. ・ Foaming agent: water ・ Diluent A: Hydrofluoroolefin (HFO) , Boiling; 19 ° C., Part No .; Solstice® 1233zd (E), Honeywell Co., Ltd.-Diluent B: Hydrofluoroolefin (HFO), Boiling point: 39 ° C., Part No .; CELEFIN 1233Z, Central Glass Co., Ltd.-Diluent C: Par Fluorocarbon (PFC), boiling point; 56 ° C., product number; PF-5060, 3M company-Plastic agent: alkyl sulphonic acid ester, boiling point; 300 ° C., product number; Memozar, Rankses company-Isocyanate: prepolymer MDI, NCO% = 27 %, Product number; M249, Sumika Cobestrourethane Co., Ltd. The weight solid content ratio in FIGS. 1 and 2 is the ratio of the heat conductive filler in the polyurethane foam raw material.

The viscosity of the polyurethane foam raw material at 20 ° C. and 30 ° C. is compared with Examples 1 to 5 and Example 7 in which the blending amount and type of the diluent are different, and Comparative Example 1 in which neither the diluent nor the plasticizer is blended. Example 9 was performed for Comparative Examples 3 to 5 in which a plasticizer was blended instead of the diluent. The viscosity was measured using a B-type viscometer (TVB-15, manufactured by Toki Sangyo Co., Ltd.). The viscosity measurement results are shown in the table of FIG. 3 and the graph of FIG.

For each of the Examples and Comparative Examples shown in FIGS. 1 and 2, the stirring time of the polyurethane foam raw material was measured, the presence or absence of poor stirring was determined, and the stirring property was evaluated. The stirring time was set in advance. For stirring, four blades having a diameter of 80 mm are used, and the rotation speed is 2000 rpm. The presence or absence of agitation failure is determined by visually observing the appearance of the molded body, and if unreacted raw material remains in the molded body, agitation failure is "Yes", and if there is no unreacted raw material, agitation failure is "No". And said. The evaluation of agitation was "○" when the agitation time was 13 seconds or less and the agitation was "absent", and "x" when the agitation time was longer than 13 seconds or the agitation was "yes". ..

The moldability was evaluated for each Example and each Comparative Example. In the evaluation of moldability, the presence or absence of molding abnormalities in the molded product was visually confirmed, and "○" was given when there were no cracks or missing meat, and "x" was given when there were cracks or missing meat.

In addition, the density (g / cm ³ ) and thermal conductivity (W / m · K) of the polyurethane foam were measured.
The density (g / cm ³ ) was measured based on JIS K 7222.
The thermal conductivity (W / m · K) was measured using a measuring instrument (QTM500, manufactured by Kyoto Denshi Kogyo Co., Ltd.) that measures the thermal conductivity using the hot wire method.
The evaluation of thermal conductivity is a value obtained by dividing the thermal conductivity by the density in consideration of the variation in the density of the molded body. Thermal conductivity / density [(W / m · K) / (g / cm ³ )] However, when it is equal to or higher than the value of the comparative example to be compared, it is evaluated as "○", and when it is lower than the value, it is evaluated as "x". The comparison targets were compared under the same conditions to be examined.
In the comprehensive evaluation, when the stirring property evaluation is "○", the moldability evaluation is "○", and the thermal conductivity evaluation is "○", the comprehensive evaluation is "○", and the stirring property evaluation, the moldability evaluation, and the heat conduction are evaluated. If any one of the sex evaluations was "x", the overall evaluation was "x".

The viscosity measurement results of FIGS. 3 and 4 will be described.
Examples 1 to 5 and 7 containing the diluents A to C have a viscosity of 29,000 to 200,000 mPa · s at 20 ° C. and a viscosity of 24,000 to 110,000 at 30 ° C., both of which have a viscosity of 29,000 to 200,000 mPa · s. Although the values were low, Comparative Examples 1 and 9 in which neither a diluent nor a plasticizer was blended and Comparative Examples 3 to 5 in which a plasticizer was blended in place of the diluent had a viscosity of 210 ° C. at 20 ° C. The viscosity at 000 to 1,400,000 mPa · s and 30 ° C. was 130,000 to 1,800,000, which was higher than that of the examples. By blending the diluents A to C in this way, the viscosities at 20 ° C. and 30 ° C. can be lowered.

Stirring property, moldability, thermal conductivity and comprehensive evaluation will be described for each Example and each Comparative Example shown in FIGS. 1 and 2.
Examples 1, 2 and 3 are examples in which the blending amount of the diluent A is changed in the range of 10 to 30 parts by weight. Further, Example 2'is an example in which the blending amount of the defoaming agent in Example 2 is 10 parts by weight to 0 parts by weight, and the others are the same as in Example 2. The comparison target of Examples 1, 2, 3 and Example 2'is Comparative Example 1 in which none of the diluents A to C and the plasticizer is blended.
In Examples 1, 2 and 3 and Example 2', the stirring time was 8 to 13 seconds, the stirring failure was "none", the stirring property evaluation was "○", the formability evaluation was "○", and the density was 1.00 to 1. 08 g / cm ³ , thermal conductivity / density value was 0.97 to 1.00, thermal conductivity evaluation was "○", and overall evaluation was "○".
In Comparative Example 1 to be compared, the stirring time was 20 seconds, the stirring property evaluation was “×”, the formability evaluation was “〇”, the density was 1.06 g / cm ³ , and the thermal conductivity / density value was 0.97. , The overall evaluation was "x".

Example 4 is an example in which 20 parts by weight of the diluent B is blended, and Example 5 is an example in which 20 parts by weight of the diluent C is blended. In Examples 4 and 5, the stirring time was 10 seconds, the stirring failure was "none", the stirring property evaluation was "○", the formability evaluation was "○", the density was 0.94 to 0.96 g / cm ³ , and the heat conduction. The rate / density values were 0.98 and 0.97, the thermal conductivity evaluation was "○", and the overall evaluation was "○".
In Comparative Example 1 to be compared, the stirring time was 20 seconds, the stirring property evaluation was “×”, the formability evaluation was “〇”, the density was 1.06 g / cm ³ , and the thermal conductivity / density value was 0.97. , The overall evaluation was "x".

In Example 6, the amount of the polyurethane foam raw material charged into the mold was increased from 164 g of Example 1 to 200 g, and the density was increased from 1.02 g / cm ³ of Example 1 to 1.20 g / cm ³ . This is an example. The comparison target is Comparative Example 6 having a density of 1.23 g / cm ³ having almost the same value.
In Example 6, the stirring time was 13 seconds, the stirring failure was “none”, the stirring property evaluation was “〇”, the formability evaluation was “〇”, the thermal conductivity / density value was 1.28, and the thermal conductivity evaluation was “〇”. , The overall evaluation was "○".
In Comparative Example 6 to be compared, the stirring time was 20 seconds, the stirring property evaluation was “×”, the formability evaluation was “〇”, the thermal conductivity / density value was 1.24, and the comprehensive evaluation was “×”.

Example 7 is an example in which the blending amounts of the thermally conductive fillers A and B are increased as compared with other examples. The comparison target is Comparative Example 9 in which the amounts of the thermally conductive fillers A and B were large and the molded product was obtained.
In Example 7, the stirring time was 12 seconds, the stirring failure was “none”, the density was 0.98 g / cm ³ , the thermal conductivity / density value was 1.07, the stirring property evaluation was “〇”, and the formability evaluation was “〇”. , The value of thermal conductivity / density was 1.07, the evaluation of thermal conductivity was "○", and the overall evaluation was "○".
In Comparative Example 9 to be compared, the stirring time was 25 seconds, the stirring property evaluation was “×”, the formability evaluation was “〇”, the density was 1.03 g / cm ³ , and the thermal conductivity / density value was 1.07. The overall rating was "x".

Comparative Example 1 is an example in which the blending amount of the diluent A in the blending of Example 1 is set to 0 parts by weight.
In Comparative Example 1, the stirring time was 20 seconds, which was longer than 13 seconds in Example 1, and the stirring property evaluation was “×”, the formability evaluation was “◯”, and the overall evaluation was “×”.
Comparative Example 2 is an example in which only the stirring time is different from that of Comparative Example 1. The comparison target is Comparative Example 1.
In Comparative Example 2, the stirring time was 13 seconds, the stirring property evaluation was “×”, and the formability evaluation was “〇”. The density and thermal conductivity could not be measured due to poor stirring property, and the overall evaluation was “×”. ..
When the blending amount of the diluent A was set to 0 parts by weight as in Comparative Example 1 and Comparative Example 2, a longer stirring time than in Example 1 was required.

Comparative Examples 3 to 5 are examples in which the same amount of plasticizer as the diluent is blended in place of the diluent A of Examples 1, 2 and 3. The comparison target is Comparative Example 1 in which neither a diluent nor a plasticizer is blended.
In Comparative Example 3, the amount of the plasticizer compounded was 10.0 parts by weight, the stirring time was 15 seconds, the stirring property evaluation was “×”, the formability evaluation was “〇”, the thermal conductivity / density value was 0.91, and the thermal conductivity. The sex evaluation was "x" and the overall evaluation was "x".
In Comparative Example 4, the amount of the plasticizer compounded was 20.0 parts by weight, the stirring time was 13 seconds, the stirring property was evaluated as “〇”, the formability was evaluated as “〇”, the thermal conductivity / density value was 0.87, and the thermal conductivity was obtained. The sex evaluation was "x" and the overall evaluation was "x".
In Comparative Example 5, the amount of the plasticizer compounded was 30.0 parts by weight, the stirring time was 10 seconds, the stirring property was evaluated as “〇”, the formability was evaluated as “〇”, the thermal conductivity / density value was 0.75, and the thermal conductivity. The sex evaluation was "x" and the overall evaluation was "x".
In Comparative Examples 3 to 5, the stirring time could be shortened by increasing the blending amount of the plasticizer, but the value of thermal conductivity / density became low (bad).

Comparative Example 6 is an example in which the blending amount of the diluent A in Example 6 is 0 parts by weight, and the amount of the mold charged is substantially equal to that of Example 6.
In Comparative Example 6, the stirring time was 20 seconds, the stirring property evaluation was “×”, the formability evaluation was “〇”, and the comprehensive evaluation was “×”.
In Comparative Example 6, neither the diluent A nor the plasticizer was blended, so that it was necessary to lengthen the stirring time.

Comparative Example 7 is an example in which the blending amount of the diluent A in Example 7 is 0 parts by weight.
In Comparative Example 7, the stirring time was 20 seconds, the stirring property evaluation was “×”, the formability evaluation was “×”, and the thermal conductivity was not measurable due to the presence of a deficiency in the molded body, and the overall evaluation was “×”.
In Comparative Example 7, since neither the diluent A nor the plasticizer was blended, the moldability was deteriorated even if the stirring time was lengthened.

Comparative Example 8 is an example in which the blending amounts of the heat conductive filler and the foaming agent (water) in Comparative Example 7 are increased.
In Comparative Example 8, the stirring time was 12 seconds, the stirring was poor, “Yes”, the stirring property was evaluated as “×”, the moldability was evaluated as “〇”, the thermal conductivity was poorly stirred, and the overall evaluation was “×”.
In Comparative Example 8, since neither the diluent A nor the plasticizer was blended, stirring was poor at a stirring time of 12 seconds.

Comparative Example 9 is an example in which the stirring time in Comparative Example 8 is increased to 25 seconds.
In Comparative Example 9, the stirring time was 25 seconds, the stirring failure was “none”, the stirring property evaluation was “×”, the formability evaluation was “〇”, the thermal conductivity / density value was 1.07, and the overall evaluation was “×”. .. In Comparative Example 9, the stirring time was lengthened, so that the stirring failure was “none”, but the stirring time was long, so that the stirring property evaluation was “x” and the overall evaluation was “x”.

Comparative Example 10 is an example in which 10 parts by weight of the diluent A was added to Comparative Example 6, the stirring time was shortened to 12 seconds, and the defoaming agent was removed from the compounding. The comparison target is Comparative Example 6.
In Comparative Example 10, the agitation evaluation “〇”, the moldability evaluation “×”, the thermal conductivity evaluation “×”, and the total The evaluation was "x".

As described above, the present invention is good because it does not require a costly magnetic field generator or the like, and even if the blending amount of the heat conductive filler is increased, poor stirring and long stirring time can be suppressed. It is possible to obtain an inexpensive polyurethane foam having excellent thermal conductivity and good moldability.
The present invention is not limited to the above embodiment, and can be modified without departing from the spirit of the invention.

Claims (6)

A polyurethane foam obtained from a polyurethane foam raw material containing a polyol, an isocyanate, a catalyst, a thermally conductive filler, and a diluent.
The blending amount of the heat conductive filler is 50 to 400 parts by weight with respect to 100 parts by weight of the polyol.
The diluent is a polyurethane foam characterized by being a physical foaming agent. The polyurethane foam according to claim 1, wherein the amount of the diluent is 10 to 30 parts by weight with respect to 100 parts by weight of the polyol. The polyurethane foam according to claim 1 or 2, wherein the polyurethane foam raw material contains a defoaming agent. In a method for producing a polyurethane foam in which a polyurethane foam raw material containing a polyol, an isocyanate, a catalyst, a heat conductive filler, and a diluent is filled in a mold and foamed.
The blending amount of the heat conductive filler is 50 to 400 parts by weight with respect to 100 parts by weight of the polyol.
A method for producing a polyurethane foam, wherein the diluent is a physical foaming agent. The method for producing a polyurethane foam according to claim 4, wherein the amount of the diluent is 10 to 30 parts by weight with respect to 100 parts by weight of the polyol. The method for producing polyurethane foam according to claim 4 or 5, wherein the polyurethane foam raw material contains a defoaming agent.

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