JP5642489B2 - Heat resistant low thermal conductive foam - Google Patents

Description

  The present invention relates to a heat resistant low thermal conductive foam. More specifically, the present invention relates to a heat-resistant and low thermal conductive foam excellent in heat resistance and excellent in low thermal conductivity.

  Foam is composed of water absorbing material, water retaining material, cushioning material, heat insulating material, sound absorbing material, separation film, reflecting material, various substrates such as circuit board, holding member such as printing plate, support member, polishing pad for polishing process and the like It is widely used in various applications such as a surface plate for supporting the substrate, a support table used for holding or transporting a semiconductor or various substrates from the back surface by vacuuming or the like.

  In recent years, among the above applications, there is a demand for low thermal conductivity (high thermal insulation). Examples of such applications include internal constituent materials for batteries, thermal diffusion sheets for electronic materials, and electromagnetic wave shields used in devices that generate a large amount of heat.

  As a foam having low thermal conductivity, a foam made of a resin composition containing a fluororesin has been reported (Patent Document 1).

  However, the foam reported in Patent Document 1 has a problem that low thermal conductivity is not yet sufficient, and a problem that it is difficult to use with a heat-generating member because of insufficient heat resistance.

JP 2008-239765 A

  The subject of this invention is providing the heat resistant low heat conductive foam excellent in heat resistance and excellent in low heat conductivity.

The heat-resistant low thermal conductive foam of the present invention is
Including a foam having spherical cells;
The thermal conductivity measured according to ASTM-D5470 is 0.1 W / m · K or less at a compression rate of 20%.

In a preferred embodiment, the heat resistant low thermal conductive foam of the present invention has a 50% compression load of 50 N / cm ² or less.

  In a preferred embodiment, the heat resistant low thermal conductive foam of the present invention has a dimensional change rate of less than ± 5% when stored at 125 ° C. for 22 hours.

  In a preferred embodiment, the heat resistant low thermal conductive foam of the present invention has a 50% compression load change rate of ± 10% or less when stored at 125 ° C. for 22 hours.

  In a preferred embodiment, the foam contains a hydrophilic polyurethane polymer.

  In a preferred embodiment, the average pore diameter of the spherical bubbles is less than 20 μm.

  In a preferred embodiment, the foam has an open cell structure having a through hole between adjacent spherical cells.

  In preferable embodiment, the average hole diameter of the said through-hole is 5 micrometers or less.

In a preferred embodiment, the density of the foam is 0.5 g / cm ³ or less.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in heat resistance and can provide the heat resistant low heat conductive foam excellent in low heat conductivity.

It is a schematic sectional drawing which shows preferable embodiment of the heat resistant low heat conductive foam of this invention. It is a schematic sectional drawing which shows another preferable embodiment of the heat resistant low heat conductive foam of this invention. It is a photograph figure of the surface / cross-section SEM photograph which image | photographed the heat-resistant low heat conductive foam produced in Example 1 from the diagonal. It is a photograph figure of the cross-sectional SEM photograph of the heat resistant low heat conductive foam of this invention, Comprising: It is a photograph figure showing clearly the open cell structure which has a through-hole between adjacent spherical bubbles. It is explanatory drawing explaining the measuring method of thermal conductivity. It is explanatory drawing explaining the cross section of the test piece in the measuring method of thermal conductivity.

≪ << A. Heat resistant low thermal conductive foam >>>>
The heat resistant low thermal conductive foam of the present invention includes a foam having spherical cells. The foam contained in the heat resistant low thermal conductive foam of the present invention preferably has an open cell structure having through holes between adjacent spherical cells. Typical structures include a heat resistant low thermal conductive foam 100 (FIG. 1) made of the foam 10 and a heat resistant low thermal conductive foam including a substrate 20 (described later) between the foam 10a and the foam 10b. 100 (FIG. 2). In FIGS. 1 and 2, the release film 30 is provided for protecting the surface of the heat-resistant low thermal conductive foam, but the release film may not be provided.

  In the present specification, the “spherical bubble” does not have to be a strict true spherical bubble, and may be, for example, a substantially spherical bubble having a partial strain or a bubble composed of a space having a large strain. .

  The average pore diameter of the spherical bubbles that the foam contained in the heat resistant low thermal conductive foam of the present invention may have is less than 20 μm, preferably 15 μm or less, more preferably 10 μm or less. The lower limit value of the average pore diameter of the spherical bubbles contained in the foam contained in the heat resistant low thermal conductive foam of the present invention is not particularly limited, and is preferably 0.01 μm, more preferably 0.1 μm, and further, Preferably it is 1 micrometer.

  When the average pore diameter of the spherical bubbles contained in the foam contained in the heat-resistant low thermal conductive foam of the present invention falls within the above range, the average pore diameter of spherical foam of the foam contained in the heat-resistant low thermal conductive foam of the present invention. It is possible to provide a heat-resistant, low thermal conductive foam that can be precisely controlled to be small, excellent in heat resistance and excellent in low thermal conductivity.

The density of heat-resistant foam in the low thermal conductive foams of the present invention is preferably not 0.5 g / cm ³ or less, more preferably from ^{0.1g / cm 3 ~0.5g / cm 3} , further preferably from ^{0.15g / cm 3 ~0.45g / cm 3} . After the density of the foam contained in the heat-resistant low thermal conductive foam of the present invention falls within the above range, the range of the density of the foam contained in the heat-resistant low thermal conductive foam of the present invention is widely controlled, It is possible to provide a heat-resistant, low thermal conductive foam excellent in heat resistance and excellent in low thermal conductivity.

  The foam contained in the heat resistant low thermal conductive foam of the present invention preferably has an open cell structure having through holes between adjacent spherical bubbles. This open cell structure may be an open cell structure having through holes between most or all adjacent spherical cells, or may be a semi-independent semi-open cell structure having a relatively small number of through holes. .

  The through-hole which has between adjacent spherical bubbles influences the physical property of a heat resistant low heat conductive foam. For example, the smaller the average pore diameter of the through holes, the higher the strength of the heat resistant low thermal conductive foam. FIG. 4 is a photograph of a cross-sectional SEM photograph of the heat-resistant low thermal conductive foam of the present invention, showing a photograph clearly representing an open cell structure having through holes between adjacent spherical bubbles.

  The average pore diameter of the through holes between adjacent spherical bubbles is preferably 5 μm or less, more preferably 4 μm or less, and even more preferably 3 μm or less. The lower limit value of the average pore diameter of the through holes between adjacent spherical bubbles is not particularly limited, and is preferably 0.001 μm, and more preferably 0.01 μm, for example. When the average pore diameter of the through holes between adjacent spherical bubbles is within the above range, it is possible to provide a heat resistant low thermal conductive foam excellent in heat resistance and excellent in low thermal conductivity.

  The heat resistant low thermal conductive foam of the present invention preferably has a surface opening on the surface. The average pore diameter of the surface opening is preferably 20 μm or less, more preferably less than 20 μm, further preferably 15 μm or less, further preferably 10 μm or less, further preferably 5 μm or less, and particularly preferably. Is 4 μm or less, and most preferably 3 μm or less. The lower limit of the average pore diameter of the surface opening is not particularly limited, and is preferably 0.001 μm, and more preferably 0.01 μm, for example. The heat-resistant low thermal conductive foam of the present invention has a surface opening, and the average pore diameter of the surface opening is within the above range, so that it has excellent heat resistance and low heat conductivity. A conductive foam can be provided.

  The heat resistant low thermal conductive foam of the present invention has very low thermal conductivity.

  The heat-resistant low thermal conductive foam of the present invention has a thermal conductivity measured in accordance with ASTM-D5470 of 0.1 W / m · K or less, preferably 0.09 W / m · K at a compression rate of 20%. Or less, more preferably 0.08 W / m · K or less. The lower limit of the thermal conductivity is preferably 0.024 W / m · K at a compression rate of 20%. The fact that the heat conductivity of the heat resistant low thermal conductive foam of the present invention falls within the above range at a compression rate of 20% means that the heat resistant low thermal conductive foam of the present invention has very low thermal conductivity. means.

  The heat-resistant low thermal conductive foam of the present invention has a thermal conductivity measured in accordance with ASTM-D5470 of 0.1 W / m · K or less at a compression rate of 5%, preferably 0.09 W / m · K. Or less, more preferably 0.08 W / m · K or less. The lower limit of the thermal conductivity is preferably 0.024 W / m · K at a compression rate of 5%. The fact that the thermal conductivity of the heat-resistant low thermal conductive foam of the present invention falls within the above range at a compression rate of 5% means that the heat-resistant low thermal conductive foam of the present invention has very low thermal conductivity. means.

  The heat resistant low thermal conductive foam of the present invention has a thermal conductivity measured in accordance with ASTM-D5470 of 0.1 W / m · K or less, preferably 0.095 W / m · K at a compression rate of 40%. Or less, more preferably 0.09 W / m · K or less. The lower limit of the thermal conductivity is preferably 0.024 W / m · K at a compression rate of 40%. The heat conductivity of the heat resistant low thermal conductive foam of the present invention falls within the above range at a compression rate of 40%. This means that the heat resistant low thermal conductive foam of the present invention has a very excellent low thermal conductivity. means.

  A specific method for measuring the thermal conductivity will be described later.

The heat resistant low thermal conductive foam of the present invention has a 50% compressive load of preferably 50 N / cm ² or less, more preferably 45 N / cm ² or less, still more preferably 40 N / cm ² or less, particularly Preferably it is 35 N / cm ² or less. The lower limit of the 50% compressive load is preferably 10 N / cm ² . When the 50% compressive load of the heat resistant low thermal conductive foam of the present invention falls within the above range, the heat resistant low thermal conductive foam of the present invention can exhibit excellent flexibility and cushioning properties.

  The heat resistant low thermal conductive foam of the present invention has a 50% compression load change rate when stored at 125 ° C. for 22 hours, preferably ± 10% or less, more preferably ± 9% or less, and still more preferably ± 8% or less. In the heat resistant low thermal conductive foam of the present invention, when the 50% compression load change rate when stored at 125 ° C. for 22 hours is within the above range, the heat resistant low thermal conductive foam of the present invention has excellent heat resistance. Can do.

  The heat resistant low thermal conductive foam of the present invention has a dimensional change rate of preferably less than ± 5%, more preferably ± 3% or less, even more preferably ± 1% when stored at 125 ° C. for 22 hours. It is as follows. When the dimensional change rate when stored at 125 ° C. for 22 hours in the heat-resistant low thermal conductive foam of the present invention falls within the above range, the heat-resistant low thermal conductive foam of the present invention can have excellent heat resistance.

  The foam contained in the heat resistant low thermal conductive foam of the present invention has a cell ratio of preferably 30% or more, more preferably 40% or more, and further preferably 50% or more. When the cell ratio falls within the above range in the heat-resistant low thermal conductive foam of the present invention, it is possible to provide a heat-resistant low thermal conductive foam excellent in heat resistance and excellent in low thermal conductivity.

  The foam contained in the heat resistant low thermal conductive foam of the present invention preferably contains a hydrophilic polyurethane polymer. Since the foam contained in the heat-resistant low thermal conductive foam of the present invention contains a hydrophilic polyurethane polymer, the cell structure is precisely controlled, the cell rate is high, and a large number of finely controlled fine cells. A heat-resistant low thermal conductive foam having a surface opening, excellent in heat resistance, and excellent in low thermal conductivity can be provided.

  The details of the foam contained in the heat resistant low thermal conductive foam of the present invention and the details of the hydrophilic polyurethane polymer contained therein will be mentioned in the description of the production method described later.

  The heat resistant low thermal conductive foam of the present invention can take any suitable shape. In the heat-resistant low thermal conductive foam of the present invention, the thickness, the long side, the short side, and the like can take any appropriate value.

  The heat resistant low thermal conductive foam of the present invention may contain any appropriate base material as long as the effects of the present invention are not impaired. Examples of the form in which the base material is contained in the heat-resistant low thermal conductive foam of the present invention include a form in which a layer of the base material is provided inside the heat-resistant low thermal conductive foam. Examples of such a substrate include fiber woven fabric, fiber nonwoven fabric, fiber laminated fabric, fiber knitted fabric, resin sheet, metal foil film sheet, and inorganic fiber.

  As the fiber woven fabric, a woven fabric formed of any appropriate fiber can be adopted. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. Further, the fiber woven fabric may be metallic processed by plating or sputtering.

  As a fiber nonwoven fabric, the nonwoven fabric formed from arbitrary appropriate fibers can be employ | adopted. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. Moreover, the fiber nonwoven fabric may be metallic-processed by plating, sputtering, etc. More specifically, for example, a spunbond nonwoven fabric can be mentioned.

  As the fiber laminated fabric, a laminated fabric formed of any appropriate fiber can be adopted. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. In addition, the fiber laminated fabric may be metallic processed by plating, sputtering, or the like. More specifically, for example, a polyester fiber laminated fabric can be mentioned.

  As a fiber knitted fabric, the knitted fabric formed from arbitrary appropriate fibers can be employ | adopted, for example. Examples of such fibers include natural fibers such as plant fibers, animal fibers, and mineral fibers; artificial fibers such as regenerated fibers, synthetic fibers, semi-synthetic fibers, and artificial inorganic fibers. Examples of synthetic fibers include fibers obtained by melt spinning thermoplastic fibers. Further, the fiber knitted fabric may be metallically processed by plating or sputtering.

  As the resin sheet, a sheet formed of any appropriate resin can be adopted. An example of such a resin is a thermoplastic resin. The resin sheet may be metallic processed by plating or sputtering.

  As the metal foil film sheet, a sheet formed from any appropriate metal foil film can be adopted.

  Any appropriate inorganic fiber can be adopted as the inorganic fiber. Specific examples of such inorganic fibers include glass fibers, metal fibers, and carbon fibers.

  In the heat-resistant low thermal conductive foam of the present invention, when voids are present in the substrate, the same material as the heat-resistant low thermal conductive foam may be present in part or all of the voids.

  Only 1 type may be used for a base material and it may use 2 or more types together.

≪≪B. Manufacturing method of heat resistant low thermal conductive foam >>>>
The heat resistant low thermal conductive foam of the present invention can be produced by any suitable method. The heat resistant low thermal conductive foam of the present invention can be preferably produced by shaping and polymerizing a W / O emulsion.

  As a manufacturing method of the heat resistant low thermal conductive foam of the present invention, for example, it can be used to continuously supply a continuous oil phase component and an aqueous phase component to an emulsifier to obtain the heat resistant low thermal conductive foam of the present invention. A “continuous method” is mentioned in which a W / O type emulsion is prepared, and then the obtained W / O type emulsion is polymerized to produce a water-containing polymer, followed by dehydration of the obtained water-containing polymer. It is done. As a method for producing the heat-resistant low thermal conductive foam of the present invention, for example, an appropriate amount of an aqueous phase component with respect to a continuous oil phase component is charged into an emulsifier, and the aqueous phase component is continuously supplied while stirring. Thus, a W / O emulsion that can be used to obtain the heat-resistant low thermal conductive foam of the present invention is prepared, and the resulting W / O emulsion is polymerized to produce a water-containing polymer. There is a “batch method” in which the obtained hydropolymer is dehydrated.

  The continuous polymerization method in which the W / O emulsion is continuously polymerized is a preferable method because the production efficiency is high and the effect of shortening the polymerization time and the shortening of the polymerization apparatus can be most effectively utilized.

More specifically, the heat-resistant low thermal conductive foam of the present invention is preferably
Step (I) of preparing a W / O emulsion that can be used to obtain the heat-resistant low thermal conductive foam of the present invention;
Step (II) of shaping the obtained W / O emulsion,
Polymerizing the shaped W / O emulsion (III);
Step (IV) of dehydrating the obtained hydrous polymer;
It can manufacture with the manufacturing method containing. Here, at least a part of the step (II) for shaping the obtained W / O emulsion and the step (III) for polymerizing the shaped W / O emulsion may be performed simultaneously.

<< B-1. Step for preparing W / O type emulsion (I) >>
The W / O type emulsion that can be used to obtain the heat resistant low thermal conductive foam of the present invention is a W / O type emulsion comprising a continuous oil phase component and an aqueous phase component that is immiscible with the continuous oil phase component. More specifically, the W / O type emulsion is obtained by dispersing an aqueous phase component in a continuous oil phase component.

  The ratio of the water phase component to the continuous oil phase component in the W / O type emulsion that can be used to obtain the heat-resistant low thermal conductive foam of the present invention is arbitrarily appropriate as long as the W / O type emulsion can be formed. A ratio can be taken. The ratio of the water phase component to the continuous oil phase component in the W / O type emulsion that can be used to obtain the heat resistant low thermal conductive foam of the present invention is the structure of the foam obtained by polymerization of the W / O type emulsion. Can be an important factor in determining mechanical, mechanical, and performance characteristics. Specifically, the ratio of the water phase component to the continuous oil phase component in the W / O type emulsion that can be used to obtain the heat resistant low thermal conductive foam of the present invention is obtained by polymerization of the W / O type emulsion. It can be an important factor in determining the density of the foam to be formed, the bubble size, the bubble structure, the dimensions of the wall forming the porous structure, and the like.

  The ratio of the aqueous phase component in the W / O emulsion that can be used to obtain the heat-resistant low thermal conductive foam of the present invention is preferably 30% by weight, more preferably 40% by weight, as the lower limit value. More preferably, it is 50% by weight, particularly preferably 55% by weight, and the upper limit is preferably 95% by weight, more preferably 90% by weight, still more preferably 85% by weight, particularly preferably. Is 80% by weight. If the ratio of the aqueous phase component in the W / O emulsion that can be used to obtain the heat-resistant low thermal conductive foam of the present invention is within the above range, the effects of the present invention can be sufficiently exhibited.

  The W / O emulsion that can be used to obtain the heat-resistant low thermal conductive foam of the present invention may contain any appropriate additive as long as the effects of the present invention are not impaired. Examples of such additives include tackifying resins; talc; calcium carbonate, magnesium carbonate, silicic acid and salts thereof, clay, mica powder, aluminum hydroxide, magnesium hydroxide, zinc white, bentonine, carbon black, Examples thereof include fillers such as silica, alumina, aluminum silicate, acetylene black, and aluminum powder; pigments; dyes; Only one kind of such an additive may be contained, or two or more kinds thereof may be contained.

  Any appropriate method can be adopted as a method for producing a W / O emulsion that can be used to obtain the heat-resistant low thermal conductive foam of the present invention. As a method for producing a W / O type emulsion that can be used for obtaining the heat resistant low thermal conductive foam of the present invention, for example, a continuous oil phase component and an aqueous phase component are continuously supplied to an emulsifier. "Continuous method" for forming O-type emulsions, or W / O type by supplying an appropriate amount of water phase components to the emulsifier and continuously supplying the water phase components with stirring to the continuous oil phase components Examples include “batch method” for forming an emulsion.

  When producing a W / O type emulsion that can be used to obtain the heat resistant low thermal conductive foam of the present invention, as a shearing means for obtaining an emulsion state, for example, a rotor stator mixer, a homogenizer, a microfluidizer, etc. Application of the high shear conditions used can be mentioned. In addition, as another shearing means for obtaining an emulsion state, for example, gentle mixing of continuous and dispersed phases by application of low shear conditions using a moving blade mixer or a pin mixer, low stirring conditions using a magnetic stir bar, etc. Can be mentioned.

  Examples of the apparatus for preparing the W / O emulsion by the “continuous method” include a static mixer, a rotor stator mixer, and a pin mixer. More intense agitation may be achieved by increasing the agitation speed or by using an apparatus designed to finely disperse the aqueous phase component in the W / O emulsion by a mixing method.

  Examples of the apparatus for preparing the W / O type emulsion by the “batch method” include manual mixing and shaking, a driven blade mixer, and three propeller mixing blades.

  Arbitrary appropriate methods can be employ | adopted as a method of preparing a continuous oil phase component. As a method for preparing the continuous oil phase component, typically, for example, a mixed syrup containing a hydrophilic polyurethane-based polymer and an ethylenically unsaturated monomer is prepared, and subsequently, a polymerization initiator, It is preferable to prepare a continuous oil phase component by blending a crosslinking agent and any other appropriate components.

  Any appropriate method can be adopted as a method of preparing the hydrophilic polyurethane-based polymer. A typical method for preparing a hydrophilic polyurethane-based polymer is, for example, by reacting polyoxyethylene polyoxypropylene glycol and a diisocyanate compound in the presence of a urethane reaction catalyst.

<B-1-1. Water phase component>
The aqueous phase component can be any aqueous fluid that is substantially immiscible with the continuous oil phase component. From the viewpoint of ease of handling and low cost, water such as ion-exchanged water is preferable.

  Any appropriate additive may be contained in the aqueous phase component as long as the effects of the present invention are not impaired. Examples of such additives include polymerization initiators and water-soluble salts. The water-soluble salt can be an effective additive for further stabilizing the W / O emulsion. Examples of such water-soluble salts include sodium carbonate, calcium carbonate, potassium carbonate, sodium phosphate, calcium phosphate, potassium phosphate, sodium chloride, potassium chloride and the like. Only one kind of such an additive may be contained, or two or more kinds thereof may be contained. The additive that can be contained in the aqueous phase component may be only one kind or two or more kinds.

<B-1-2. Continuous oil phase component>
The continuous oil phase component preferably contains a hydrophilic polyurethane polymer and an ethylenically unsaturated monomer. The content ratio of the hydrophilic polyurethane polymer and the ethylenically unsaturated monomer in the continuous oil phase component can take any appropriate content ratio as long as the effects of the present invention are not impaired.

  The hydrophilic polyurethane-based polymer depends on the polyoxyethylene ratio in the polyoxyethylene polyoxypropylene glycol unit constituting the hydrophilic polyurethane-based polymer or the amount of the aqueous phase component to be blended. The hydrophilic polyurethane polymer is in the range of 10 to 30 parts by weight with respect to 70 to 90 parts by weight of the ethylenically unsaturated monomer, and more preferably hydrophilic to 75 to 90 parts by weight of the ethylenically unsaturated monomer. The polyurethane polymer is in the range of 10 to 25 parts by weight. Further, for example, the hydrophilic polyurethane polymer is preferably in the range of 1 to 30 parts by weight, more preferably 1 to 25 parts by weight of the hydrophilic polyurethane polymer with respect to 100 parts by weight of the aqueous phase component. It is a range. If the content ratio of the hydrophilic polyurethane polymer is within the above range, the effects of the present invention can be sufficiently exhibited.

(B-1-2-1. Hydrophilic polyurethane polymer)
The hydrophilic polyurethane-based polymer preferably contains a polyoxyethylene polyoxypropylene unit derived from polyoxyethylene polyoxypropylene glycol, and 5 wt% to 25 wt% in the polyoxyethylene polyoxypropylene unit is polyoxyethylene. Ethylene.

  The content ratio of polyoxyethylene in the polyoxyethylene polyoxypropylene unit is preferably 5% by weight to 25% by weight as described above, and is more preferably 10% by weight as the lower limit, and the upper limit. More preferably, it is 25% by weight, and more preferably 20% by weight. The polyoxyethylene in the polyoxyethylene polyoxypropylene unit exhibits an effect of stably dispersing the aqueous phase component in the continuous oil phase component. When the content of polyoxyethylene in the polyoxyethylene polyoxypropylene unit is less than 5% by weight, it may be difficult to stably disperse the water phase component in the continuous oil phase component. If the polyoxyethylene content in the polyoxyethylene polyoxypropylene unit exceeds 25% by weight, there is a risk of phase inversion from a W / O type emulsion to an O / W type (oil-in-water type) emulsion as it approaches the HIPE condition. There is.

  A conventional hydrophilic polyurethane polymer can be obtained by reacting a diisocyanate compound with a hydrophobic long-chain diol, polyoxyethylene glycol and derivatives thereof, and a low molecular active hydrogen compound (chain extender). Since the number of polyoxyethylene groups contained in the hydrophilic polyurethane polymer obtained in 1) is uneven, the emulsion stability of such a W / O emulsion containing such a hydrophilic polyurethane polymer may be reduced. There is. On the other hand, the hydrophilic polyurethane-based polymer contained in the continuous oil phase component of the W / O emulsion that can be used to obtain the heat-resistant low thermal conductive foam of the present invention has the above-described characteristic structure. When included in the continuous oil phase component of the W / O type emulsion, excellent emulsifying properties and excellent stationary storage stability can be expressed without positively adding an emulsifier or the like.

  The hydrophilic polyurethane-based polymer is preferably obtained by reacting polyoxyethylene polyoxypropylene glycol and a diisocyanate compound. In this case, the ratio between the polyoxyethylene polyoxypropylene glycol and the diisocyanate compound is NCO / OH (equivalent ratio), and the lower limit is preferably 1, more preferably 1.2, and still more preferably 1. .4, particularly preferably 1.6, and the upper limit is preferably 3, more preferably 2.5, and even more preferably 2. When NCO / OH (equivalent ratio) is less than 1, a gelled product may be easily formed when a hydrophilic polyurethane polymer is produced. When NCO / OH (equivalent ratio) exceeds 3, the residual diisocyanate compound increases, and the W / O emulsion that can be used to obtain the heat-resistant low thermal conductive foam of the present invention may become unstable. is there.

  As polyoxyethylene polyoxypropylene glycol, for example, polyether polyol (ADEKA (registered trademark) Pluronic L-31, L-61, L-71, L-101, L-121, L-42 manufactured by ADEKA Corporation) , L-62, L-72, L-122, 25R-1, 25R-2, 17R-2) and polyoxyethylene polyoxypropylene glycol (Pronon (registered trademark) 052, 102, manufactured by NOF Corporation. 202). As for polyoxyethylene polyoxypropylene glycol, only 1 type may be used and 2 or more types may be used together.

  Examples of the diisocyanate compound include aromatic, aliphatic, and alicyclic diisocyanates, dimers and trimers of these diisocyanates, polyphenylmethane polyisocyanate, and the like. Aromatic, aliphatic, and alicyclic diisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate. 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, butane-1,4-diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4 -Diisocyanate, dicyclohexylmethane-4,4-diisocyanate, 1,3-bis (isocyanatemethyl) cyclohexane, methyl Cyclohexane diisocyanate, m- tetramethylxylylene diisocyanate. Examples of the diisocyanate trimer include isocyanurate type, burette type, and allophanate type. Only 1 type may be used for a diisocyanate compound and it may use 2 or more types together.

  The diisocyanate compound may be selected as appropriate from the viewpoint of urethane reactivity with the polyol and the like, as well as the type and combination thereof. From the viewpoint of rapid urethane reactivity with polyol and suppression of reaction with water, it is preferable to use alicyclic diisocyanate.

  The weight average molecular weight of the hydrophilic polyurethane polymer is preferably 5000 as a lower limit, more preferably 7000, still more preferably 8000, particularly preferably 10,000, and preferably 50,000 as an upper limit. More preferably, it is 40000, more preferably 30000, and particularly preferably 20000.

  The hydrophilic polyurethane polymer may have an unsaturated double bond capable of radical polymerization at the terminal. By having an unsaturated double bond capable of radical polymerization at the terminal of the hydrophilic polyurethane-based polymer, the effects of the present invention can be further exhibited.

(B-1-2-2. Ethylenically unsaturated monomer)
As the ethylenically unsaturated monomer, any appropriate monomer can be adopted as long as it is a monomer having an ethylenically unsaturated double bond. Only one type of ethylenically unsaturated monomer may be used, or two or more types may be used.

  The ethylenically unsaturated monomer preferably comprises a (meth) acrylic ester. The content ratio of the (meth) acrylic acid ester in the ethylenically unsaturated monomer is preferably 80% by weight, more preferably 85% by weight as the lower limit, and preferably 100% by weight as the upper limit. More preferably, it is 98% by weight. Only one (meth) acrylic acid ester may be used, or two or more may be used.

  The (meth) acrylic acid ester is preferably an alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms (a concept including a cycloalkyl group, an alkyl (cycloalkyl) group, and a (cycloalkyl) alkyl group). It is. Preferably the carbon number of the said alkyl group is 4-18. In addition, (meth) acryl means acryl and / or methacryl, and (meth) acrylate means acrylate and / or methacrylate.

  Examples of the alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, and s-butyl. (Meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, isoamyl (meth) Acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isode Ru (meth) acrylate, n-dodecyl (meth) acrylate, isomyristyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, pentadecyl (Meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, isostearyl (meth) acrylate, isobornyl (meth) acrylate, etc. It is done. Among these, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isobornyl (meth) acrylate are preferable. Only 1 type may be sufficient as the alkyl (meth) acrylate which has a C1-C20 alkyl group, and 2 or more types may be sufficient as it.

  The ethylenically unsaturated monomer preferably further comprises a polar monomer copolymerizable with the (meth) acrylic acid ester. The content of the polar monomer in the ethylenically unsaturated monomer is preferably 0% by weight, more preferably 2% by weight as the lower limit, and preferably 20% by weight, more preferably as the upper limit. 15% by weight. Only one type of polar monomer may be used, or two or more types may be used.

  Examples of polar monomers include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, ω-carboxy-polycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, itaconic acid, maleic acid, fumaric acid Carboxyl group-containing monomers such as acid and crotonic acid; acid anhydride monomers such as maleic anhydride and itaconic anhydride; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and (meth) acrylic acid 4-hydroxybutyl, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethyl Shi And hydroxyl group-containing monomers such as chlorohexyl) methyl (meth) acrylate; amide group-containing monomers such as N, N-dimethyl (meth) acrylamide and N, N-diethyl (meth) acrylamide;

(B-1-2-3. Polymerization initiator)
The continuous oil phase component preferably contains a polymerization initiator.

  Examples of the polymerization initiator include radical polymerization initiators and redox polymerization initiators. Examples of the radical polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator.

  Examples of the thermal polymerization initiator include azo compounds, peroxides, peroxycarbonic acid, peroxycarboxylic acid, potassium persulfate, t-butylperoxyisobutyrate, and 2,2′-azobisisobutyronitrile. .

  Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone (for example, Ciba Japan, trade name: Darocur-2959), α-hydroxy- α, α'-dimethylacetophenone (for example, Ciba Japan, trade name: Darocur-1173), methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone (for example, Ciba Japan, trade name) Acetophenone photopolymerization initiators such as Irgacure-651) and 2-hydroxy-2-cyclohexylacetophenone (for example, Ciba Japan, trade name; Irgacure-184); Ketal photopolymerization initiator such as benzyldimethyl ketal Agents; Other halogenated ketones; Acylphosphine oxides (As an example, Ciba Japan Co., Ltd., trade name: Irgacure -819); and the like.

  The polymerization initiator may contain only 1 type and may contain 2 or more types.

  The content of the polymerization initiator is preferably 0.05% by weight, more preferably 0.1% by weight, more preferably 0.1%, and preferably 5.0% as a lower limit with respect to the entire continuous oil phase component. % By weight, more preferably 1.0% by weight. When the content of the polymerization initiator is less than 0.05% by weight based on the entire continuous oil phase component, the amount of unreacted monomer components increases, and the amount of residual monomers in the resulting heat resistant low thermal conductive foam increases. There is a risk. When the content of the polymerization initiator exceeds 5.0% by weight with respect to the entire continuous oil phase component, the mechanical properties of the resulting heat resistant low thermal conductive foam may be lowered.

  Note that the amount of radicals generated by the photopolymerization initiator varies depending on the type and intensity of light to be irradiated, the irradiation time, the amount of dissolved oxygen in the monomer and solvent mixture, and the like. And when there is much dissolved oxygen, the radical generation amount by a photoinitiator is suppressed, superposition | polymerization does not fully advance and an unreacted substance may increase. Therefore, it is preferable to blow an inert gas such as nitrogen into the reaction system and replace oxygen with the inert gas before the light irradiation.

(B-1-2-4. Crosslinking agent)
The continuous oil phase component preferably includes a cross-linking agent.

  Crosslinking agents are typically used to link polymer chains together to build a more three-dimensional molecular structure. The selection of the type and content of the cross-linking agent depends on the structural, mechanical and fluid treatment properties desired for the resulting heat resistant low thermal conductive foam. The selection of the specific type and content of the cross-linking agent is important in achieving a desirable combination of structural properties, mechanical properties, and fluid treatment properties of the heat resistant low thermal conductive foam.

  In producing the heat-resistant low thermal conductive foam of the present invention, preferably, at least two kinds of crosslinking agents having different weight average molecular weights are used as the crosslinking agent.

  In producing the heat-resistant low thermal conductive foam of the present invention, more preferably, as the crosslinking agent, “polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamide, and polymerization reactivity”. “One or more selected from oligomers” and “one or more selected from polyfunctional (meth) acrylates and polyfunctional (meth) acrylamides having a weight average molecular weight of 500 or less” are used in combination. Here, the polyfunctional (meth) acrylate is specifically a polyfunctional (meth) acrylate having at least two ethylenically unsaturated groups in one molecule, and the polyfunctional (meth) acrylamide is Specifically, it is polyfunctional (meth) acrylamide having at least two ethylenically unsaturated groups in one molecule.

  Examples of the polyfunctional (meth) acrylate include diacrylates, triacrylates, tetraacrylates, dimethacrylates, trimethacrylates, and tetramethacrylates.

  Examples of the polyfunctional (meth) acrylamide include diacrylamides, triacrylamides, tetraacrylamides, dimethacrylamides, trimethacrylamides, tetramethacrylamides and the like.

  The polyfunctional (meth) acrylate can be derived from, for example, diols, triols, tetraols, bisphenol A and the like. Specifically, for example, 1,10-decanediol, 1,8-octanediol, 1,6 hexanediol, 1,4-butanediol, 1,3-butanediol, 1,4 butane-2-enediol , Ethylene glycol, diethylene glycol, trimethylolpropane, pentaerythritol, hydroquinone, catechol, resorcinol, triethylene glycol, polyethylene glycol, sorbitol, polypropylene glycol, polytetramethylene glycol, modified bisphenol A propylene oxide, and the like.

  The polyfunctional (meth) acrylamide can be derived from, for example, corresponding diamines, triamines, tetraamines and the like.

  Examples of the polymerization reactive oligomer include urethane (meth) acrylate, epoxy (meth) acrylate, copolyester (meth) acrylate, oligomer di (meth) acrylate and the like. Preferably, it is hydrophobic urethane (meth) acrylate.

  The weight average molecular weight of the polymerization reactive oligomer is preferably 1500 or more, more preferably 2000 or more. Although the upper limit of the weight average molecular weight of a polymerization reactive oligomer is not specifically limited, For example, Preferably it is 10,000 or less.

  As the cross-linking agent, “one or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamides, and polymerization reactive oligomers” and “a weight average molecular weight of 500 or less. When using together with “one or more selected from functional (meth) acrylate and polyfunctional (meth) acrylamide” ”,“ polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamide, and polymerization ” The amount of “one or more selected from reactive oligomers” is preferably 40% by weight as a lower limit with respect to the total amount of the hydrophilic polyurethane polymer and the ethylenically unsaturated monomer in the continuous oil phase component. The upper limit is preferably 100% by weight, and more preferably 80% by weight. The amount of use of “one or more selected from a polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, a polyfunctional (meth) acrylamide, and a polymerization reactive oligomer” is a hydrophilic polyurethane-based heavy in the continuous oil phase component If it is less than 40% by weight based on the total amount of the coalesced and ethylenically unsaturated monomer, the cohesive strength of the resulting heat-resistant low thermal conductive foam may be reduced, making it difficult to achieve both toughness and flexibility. There is a risk. The amount of use of “one or more selected from a polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, a polyfunctional (meth) acrylamide, and a polymerization reactive oligomer” is a hydrophilic polyurethane-based heavy in the continuous oil phase component When it exceeds 100% by weight with respect to the total amount of the coalesced monomer and the ethylenically unsaturated monomer, the emulsion stability of the W / O type emulsion is lowered, and the desired heat resistant low thermal conductive foam may not be obtained. .

  As the cross-linking agent, “one or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamides, and polymerization reactive oligomers” and “a weight average molecular weight of 500 or less. When using together with “one or more selected from functional (meth) acrylate and polyfunctional (meth) acrylamide” ”,“ selected from polyfunctional (meth) acrylate and polyfunctional (meth) acrylamide having a weight average molecular weight of 500 or less ” The amount of “one or more” used is preferably 1% by weight, more preferably 5% as a lower limit with respect to the total amount of the hydrophilic polyurethane polymer and the ethylenically unsaturated monomer in the continuous oil phase component. The upper limit is preferably 30% by weight, and more preferably 20% by weight. Use amount of “one or more selected from polyfunctional (meth) acrylate having a weight average molecular weight of 500 or less and polyfunctional (meth) acrylamide” is a hydrophilic polyurethane polymer and ethylenic unsaturated in a continuous oil phase component When the amount is less than 1% by weight based on the total amount of monomers, the heat resistance is lowered, and the cell structure may be crushed by contraction in the step (IV) of dehydrating the water-containing polymer. Use amount of “one or more selected from polyfunctional (meth) acrylate having a weight average molecular weight of 500 or less and polyfunctional (meth) acrylamide” is a hydrophilic polyurethane polymer and ethylenic unsaturated in a continuous oil phase component When it exceeds 30 weight% with respect to the total amount of a monomer, the toughness of the heat-resistant low-heat-conductive foam obtained may fall, and there exists a possibility that it may show brittleness.

  The crosslinking agent may contain only 1 type and may contain 2 or more types.

(B-1-2-5. Other components in the continuous oil phase component)
The continuous oil phase component may contain any appropriate other component as long as the effects of the present invention are not impaired. Typically, such other components preferably include a catalyst, an antioxidant, an organic solvent, and the like. Such other components may be only one type or two or more types.

  Examples of the catalyst include a urethane reaction catalyst. Any appropriate catalyst can be adopted as the urethane reaction catalyst. Specific examples include dibutyltin dilaurate.

  Arbitrary appropriate content rates can be employ | adopted for the content rate of a catalyst according to the target catalytic reaction.

  The catalyst may contain only 1 type and may contain 2 or more types.

  Examples of the antioxidant include a phenol-based antioxidant, a thioether-based antioxidant, and a phosphorus-based antioxidant.

  Arbitrary appropriate content rates can be employ | adopted for the content rate of antioxidant in the range which does not impair the effect of this invention.

  Antioxidant may contain only 1 type and may contain 2 or more types.

  Any appropriate organic solvent can be adopted as the organic solvent as long as the effects of the present invention are not impaired.

  Arbitrary appropriate content rates can be employ | adopted for the content rate of an organic solvent in the range which does not impair the effect of this invention.

  The organic solvent may contain only 1 type and may contain 2 or more types.

<< B-2. Step of shaping W / O type emulsion (II) >>
In the step (II), any appropriate shaping method can be adopted as a method for shaping the W / O type emulsion. For example, there is a method in which a W / O emulsion is continuously supplied onto a traveling belt and shaped into a smooth sheet on the belt. Moreover, the method of apply | coating to one surface of a thermoplastic resin film, and shaping is mentioned.

  In the step (II), as a method of shaping the W / O type emulsion, when adopting a method of coating and shaping on one surface of a thermoplastic resin film, as a method of coating, for example, a roll coater, Examples include a method using a die coater, a knife coater, or the like.

<< B-3. Step of polymerizing shaped W / O emulsion (III) >>
In the step (III), any appropriate polymerization method can be adopted as a method for polymerizing the shaped W / O emulsion. For example, the belt surface of a belt conveyor is heated by a heating device, and a W / O type emulsion is continuously supplied onto a traveling belt and shaped into a smooth sheet on the belt by heating. A W / O emulsion is continuously supplied onto the running belt, with a method of polymerization and a structure in which the belt surface of the belt conveyor is heated by irradiation of active energy rays, and a smooth sheet is formed on the belt. The method of superposing | polymerizing by irradiation of an active energy ray is mentioned, shaping.

  In the case of polymerization by heating, the polymerization temperature (heating temperature) is preferably 23 ° C., more preferably 50 ° C., still more preferably 70 ° C., particularly preferably 80 ° C. as the lower limit. The upper limit is preferably 90 ° C, and is preferably 150 ° C, more preferably 130 ° C, and even more preferably 110 ° C. When the polymerization temperature is less than 23 ° C., the polymerization takes a long time, and industrial productivity may be reduced. When the polymerization temperature exceeds 150 ° C., the pore diameter of the resulting heat-resistant low thermal conductive foam may be non-uniform, and the strength of the heat-resistant low thermal conductive foam may be reduced. The polymerization temperature need not be constant. For example, the polymerization temperature may be varied in two stages or multiple stages during the polymerization.

  In the case of polymerization by irradiation with active energy rays, examples of the active energy rays include ultraviolet rays, visible rays, and electron beams. The active energy ray is preferably ultraviolet light or visible light, and more preferably visible to ultraviolet light having a wavelength of 200 nm to 800 nm. Since the W / O type emulsion has a strong tendency to scatter light, it is possible to penetrate the W / O type emulsion by using visible to ultraviolet light having a wavelength of 200 nm to 800 nm. Moreover, the photoinitiator which can be activated with a wavelength of 200 nm-800 nm is easy to obtain, and a light source is easy to obtain.

  The wavelength of the active energy ray is preferably 200 nm, more preferably 300 nm as the lower limit value, and preferably 800 nm, more preferably 450 nm as the upper limit value.

  As a typical apparatus used for irradiation of active energy rays, for example, an ultraviolet lamp capable of performing ultraviolet irradiation includes an apparatus having a spectral distribution in a wavelength region of 300 to 400 nm. , Black light (trade name manufactured by Toshiba Lighting & Technology Co., Ltd.), metal halide lamp and the like.

  The illuminance at the time of irradiation with active energy rays can be set to any appropriate illuminance by adjusting the distance from the irradiation device to the irradiation object and the voltage. For example, by the method disclosed in Japanese Patent Application Laid-Open No. 2003-13015, the ultraviolet irradiation in each step is performed in a plurality of stages, thereby making it possible to precisely adjust the adhesive performance.

  In order to prevent the adverse effect of oxygen having an inhibitory action on the ultraviolet rays, for example, a W / O emulsion is applied to one surface of a substrate such as a thermoplastic resin film and then shaped under an inert gas atmosphere. UV rays such as polyethylene terephthalate coated with a release agent such as silicone after passing through a W / O emulsion on one surface of a substrate such as a thermoplastic resin film and shaping, but blocking oxygen It is preferable to carry out by covering the film.

  As the thermoplastic resin film, any appropriate thermoplastic resin film can be adopted as long as it can be formed by coating a W / O emulsion on one surface. Examples of the thermoplastic resin film include plastic films and sheets such as polyester, olefin resin, and polyvinyl chloride.

  The inert gas atmosphere refers to an atmosphere in which oxygen in the light irradiation zone is replaced with an inert gas. Therefore, in the inert gas atmosphere, it is necessary that oxygen is not present as much as possible, and the oxygen concentration is preferably 5000 ppm or less.

<< B-4. Step of dehydrating the obtained water-containing polymer (IV) >>
In step (IV), the obtained water-containing polymer is dehydrated. In the water-containing polymer obtained in step (III), the aqueous phase component is present in a dispersed state. By removing the aqueous phase component by dehydration and drying, a foam contained in the heat-resistant low thermal conductive foam of the present invention is obtained. The obtained foam can be used as it is as the heat-resistant low thermal conductive foam of the present invention. Further, as described later, by combining with a base material, the heat resistant low thermal conductive foam of the present invention can be obtained.

  Arbitrary appropriate drying methods can be employ | adopted as a dehydration method in process (IV). Examples of such a drying method include vacuum drying, freeze drying, press drying, microwave drying, drying in a heat oven, drying with infrared rays, or a combination of these techniques.

<< B-5. When the heat-resistant low thermal conductive foam of the present invention contains a base material >>
When the heat-resistant low thermal conductive foam of the present invention contains a substrate, as one preferred embodiment of the method for producing the heat-resistant low thermal conductive foam of the present invention, a W / O emulsion is applied to one surface of the substrate. W / O type emulsion by heating or irradiation with active energy rays in an inert gas atmosphere or in a state where oxygen is blocked by coating with a UV transparent film coated with a release agent such as silicone Is obtained as a water-containing polymer, and the resulting water-containing polymer is dehydrated to form a heat-resistant low thermal conductive foam having a substrate / foamed layer laminated structure.

  As another preferred embodiment of the method for producing the heat-resistant low thermal conductive foam of the present invention, a W / O emulsion is applied to one surface of an ultraviolet transmissive film coated with a release agent such as silicone. A sheet is prepared, a substrate is laminated on the coated surface of one of the two W / O emulsion coated sheets, and another W / O emulsion is formed on the other surface of the laminated substrate. In a state where the coated surfaces of the coated sheets are laminated so as to match with each other, by heating or irradiating active energy rays, the W / O emulsion is polymerized to form a hydrous polymer, and the obtained hydrous polymer is dehydrated. And a heat-resistant low thermal conductive foam having a laminated structure of foam layer / base material / foam layer.

  Examples of the method of coating the W / O type emulsion on one side of the base material or one surface of the ultraviolet ray transmissive film coated with a release agent such as silicone include a roll coater, a die coater, and a knife coater.

  Hereinafter, although the present invention is explained based on an example, the present invention is not limited to these. The normal temperature means 23 ° C.

(Molecular weight measurement)
The weight average molecular weight was determined by GPC (gel permeation chromatography).
Equipment: “HLC-8020” manufactured by Tosoh Corporation
Column: “TSKgel GMH _HR- H (20)” manufactured by Tosoh Corporation
Solvent: Tetrahydrofuran Standard: Polystyrene

(Measurement of average pore diameter)
The obtained foam was cut in the thickness direction with a microtome cutter as a measurement sample. The cut surface of the sample for measurement was photographed with a scanning electron microscope (Hitachi, S-3400N) at 800 to 5000 times. Using the photographed image, measure the pore diameter of an arbitrary range of spherical bubbles, the diameter of a through-hole penetrating between the spherical bubbles of an arbitrary range, and the pore diameter of the surface opening of an arbitrary range. The average hole diameter, the average hole diameter of the through holes, and the average hole diameter of the surface openings were calculated.

(Measurement of 50% compression load)
The obtained foam was punched out to 25 mm × 25 mm, and then 5 sheets were laminated to obtain a measurement sample. Tensilon was used for measurement, and at room temperature, the sample for measurement was compressed in the thickness direction to 50% of the initial thickness at a speed of 10 mm / min, and the maximum value when the thickness was compressed by 50% was measured. . Samples were measured at n = 2, and the average value was 50% compression load.

(Measurement of 50% compression load change rate)
A sample for measurement of 50% compressive load was stored in an oven at 100 ° C. for 22 hours, or in an oven at 125 ° C. for 22 hours, or in an oven at 150 ° C. for 22 hours. The rate of change in 50% compression load before and after the heat storage treatment was determined.

(Measurement of thermal conductivity)
In accordance with ASTM-D5470 (American Society for Testing and Materials Standards), thermal conductivity was measured using a thermal property evaluation apparatus shown in FIGS.
Specifically, a test piece (20 mm × 20 mm) is sandwiched between a pair of rods L made of aluminum (A5052, thermal conductivity: 140 W / m · K) formed so as to be a cube having a side of 20 mm. It is.
And it arrange | positioned between the heat generating body (heater block) H and the heat radiating body (cooling base board comprised so that a cooling water may circulate through the inside) C so that a pair of rod may become up and down. Specifically, the heating element H is disposed on the upper rod L, and the radiator C is disposed below the rod L on the lower side.
At this time, the pair of rods L are positioned between a pair of pressure adjusting screws T penetrating the heating element and the heat radiating body. A load cell R is disposed between the pressure adjusting screw T and the heating element H, and is configured to measure the pressure when the pressure adjusting screw T is tightened. Was the pressure applied to the specimen.
Further, three probes P (diameter 1 mm) of a contact-type displacement meter were installed so as to penetrate the lower rod L and the test piece from the radiator C side. At this time, the upper end portion of the probe P is in contact with the surface of the upper rod L, and the distance between the upper and lower rods L (the thickness of the test piece) can be measured.
A temperature sensor D was attached to the heating element H and the upper and lower rods L. Specifically, the temperature sensor D was attached at one place on the heating element H and five places at intervals of 5 mm in the vertical direction of each rod L.
In the measurement, first, the pressure adjusting screw T was tightened, pressure was applied to the test piece, the temperature of the heating element H was set to 80 ° C., and cooling water of 20 ° C. was circulated through the radiator C.
Then, after the temperature of the heating element H and the upper and lower rods L is stabilized, the temperature of the upper and lower rods L is measured by each temperature sensor D, and the heat flow passing through the test piece from the thermal conductivity and temperature gradient of the upper and lower rods L While calculating a bundle | flux, the temperature of the interface with the test piece of the upper and lower rod L was calculated. And the heat conductivity (W / m * K) in the said compressibility was computed using these.

(Measurement of heating dimensional change rate)
The dimensional change in heating of the foam was measured in accordance with the dimensional stability evaluation at high temperature of JIS-K-6767. That is, the obtained foam was cut into a size of 100 mm × 100 mm to obtain a test piece, which was stored in an oven at 125 ° C. for 22 hours, and then conformed to the dimensional stability evaluation at high temperature of JIS-K-6767. The dimensional change rate before and after the heat storage treatment was determined.

(Density measurement)
Five pieces of the obtained foam were cut into a size of 100 mm × 100 mm to obtain test pieces, and the apparent density was determined by dividing the weight by the volume. The average value of the apparent density obtained was taken as the density of the foam.

(Measurement of bubble rate)
Only the oil phase component at the time of producing the emulsion was polymerized, and the obtained polymer sheet was cut into five pieces of 100 mm × 100 mm to obtain test pieces, and the apparent density was obtained by dividing the weight by the volume. The average value of the apparent density obtained was taken as the density of the resin component constituting the foam. The foam ratio of the foam was calculated by the following formula using a relative density obtained by dividing the density of the foam by the density of the resin component.
Bubble ratio = (1−relative density) × 100

[Production Example 1]: Preparation of mixed syrup 1 In a reaction vessel equipped with a condenser, a thermometer, and a stirrer, 2-ethylhexyl acrylate (manufactured by Toagosei Co., Ltd., hereinafter "2EHA") as an ethylenically unsaturated monomer A monomer solution consisting of 173.2 parts by weight, and 100 parts by weight of Adeka (registered trademark) Pluronic L-62 (molecular weight 2500, manufactured by ADEKA Corporation, polyether polyol) as polyoxyethylene polyoxypropylene glycol, Dibutyltin dilaurate (manufactured by Kishida Chemical Co., Ltd., hereinafter abbreviated as “DBTL”) as a urethane reaction catalyst was added in an amount of 0.014 part by weight, and while stirring, hydrogenated xylylene diisocyanate (manufactured by Takeda Pharmaceutical Co., Ltd., Takenate). 600, hereinafter abbreviated as “HXDI”) 12.4 parts by weight were added dropwise and reacted at 65 ° C. for 4 hours. Let In addition, the usage-amount of the polyisocyanate component and the polyol component was NCO / OH (equivalent ratio) = 1.6. Thereafter, 5.6 parts by weight of 2-hydroxyethyl acrylate (manufactured by Kishida Chemical Co., Ltd., hereinafter abbreviated as “HEA”) is dropped and reacted at 65 ° C. for 2 hours, and a hydrophilic polyurethane system having acryloyl groups at both ends. A polymer / ethylenically unsaturated monomer mixed syrup was obtained. The weight average molecular weight of the obtained hydrophilic polyurethane polymer was 15,000. 25 parts by weight of 2EHA, 56 parts by weight of n-butyl acrylate (manufactured by Toa Gosei Co., Ltd., hereinafter abbreviated as “BA”) per 100 parts by weight of the obtained hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup, 17.9 parts by weight of isobornyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., hereinafter referred to as “IBXA”) and 10.7 parts by weight of acrylic acid (manufactured by Toagosei Co., Ltd., hereinafter referred to as “AA”) as a polar monomer In addition, a hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup 1 was obtained.

[Example 1]
To 100 parts by weight of the hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup 1 obtained in Production Example 1, 1,6-hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester A” -HD-N ") (molecular weight 226) 11.9 parts by weight, synthesized as a reactive oligomer from polytetramethylene glycol (hereinafter abbreviated as" PTMG ") and isophorone diisocyanate (hereinafter abbreviated as" IPDI "). A polyurethane acrylate having both ends of polyurethane treated with HEA and having an ethylenically unsaturated group at both ends (hereinafter abbreviated as “UA”) (molecular weight 3720), 47.7 parts by weight, diphenyl (2,4,6- Trimethylbenzoyl) phosphine oxide (BASF, trade name “Lucirin TPO”) 0.41 parts by weight, hinder De phenolic antioxidant (manufactured by Ciba Japan, trade name "Irganox 1010") 0.69 part by weight were uniformly mixed, continuous oil phase component (hereinafter, referred to as "oil phase") was. On the other hand, 300 parts by weight of ion-exchanged water as an aqueous phase component (hereinafter referred to as “aqueous phase”) with respect to 100 parts by weight of the oil phase is continuously introduced into a stirring mixer that is an emulsifier charged with the oil phase at room temperature. Were added dropwise to prepare a stable W / O emulsion. The weight ratio of the water phase to the oil phase was 75/25.
The obtained W / O emulsion was stored at room temperature for 1 hour, and then applied onto a substrate that had been subjected to a release treatment so that the thickness after light irradiation was 1 mm, and was continuously molded. Further, a polyethylene terephthalate film having a thickness of 38 μm and subjected to a release treatment was placed thereon. This sheet was irradiated with ultraviolet light having a light illuminance of 5 mW / cm ² (measured with Topcon UVR-T1 having a peak sensitivity maximum wave of 350 nm) using black light (15 W / cm) to obtain a highly hydrous crosslinked polymer having a thickness of 1 mm. . Next, the top film was peeled off, and the high water content crosslinked polymer was heated at 130 ° C. for 20 minutes to obtain a heat resistant low thermal conductive foam (1) having a thickness of about 1 mm.
The results are shown in Table 1.
Moreover, the photograph figure of the surface / cross-section SEM photograph which image | photographed the heat-resistant low heat conductive foam (1) obtained from the diagonal was shown in FIG.

[Example 2]
A stable W / O emulsion was prepared in the same manner as in Example 1 except that 230 parts by weight of ion-exchanged water was continuously added dropwise at room temperature as the aqueous phase. The weight ratio of the water phase to the oil phase was 60/40.
The foamed layer after light irradiation was applied to a 38 μm-thick polyethylene terephthalate film (hereinafter referred to as “PET film”), which was a W / O emulsion that had been stored at room temperature for 30 minutes. The film was applied to a thickness of 500 μm and continuously formed into a sheet shape. Further, a 70 μm thick polyester fiber laminate fabric (manufactured by JX Nippon Mining & Chemicals, Inc., trade name “MILIFE (registered trademark) TY0505FE”) in which polyester long fibers are vertically aligned and laminated is laminated thereon. Further, separately from the preparation, the W / O-type emulsion that has been stored at room temperature for 30 minutes is placed on a PET film having a thickness of 38 μm that has been subjected to a release treatment so that the thickness of the foamed layer after light irradiation is 500 μm. A coated material was prepared, and the coated surface was covered with the polyester fiber laminated fabric. This sheet was irradiated with ultraviolet light having a light illuminance of 5 mW / cm ² (measured with Topcon UVR-T1 having a peak sensitivity maximum wave of 350 nm) using black light (15 W / cm) to obtain a highly hydrous crosslinked polymer having a thickness of 1 mm. . Next, the top film was peeled off, and the high water content crosslinked polymer was heated at 130 ° C. for 20 minutes to obtain a heat resistant low thermal conductive foam (2) having a thickness of about 1 mm.
The results are shown in Table 1.

  The heat-resistant low thermal conductive foam of the present invention can be preferably used for various members such as internal constituent materials for batteries, heat insulating sheets or heat diffusion sheets for electronic materials, and electromagnetic wave shields used in devices with a large amount of heat generation.

100 heat-resistant low thermal conductive foam 10 foam 10a foam 10b foam 20 base material 30 release film

Claims (9)

Including a foam having spherical cells;
The foam is a foam obtained by polymerizing a W / O emulsion in which a water phase component is dispersed in a continuous oil phase component.
The continuous oil phase component includes a hydrophilic polyurethane polymer and an ethylenically unsaturated monomer,
The thermal conductivity measured according to ASTM-D5470 is 0.1 W / m · K or less at a compression rate of 20%.
Heat resistant low thermal conductive foam. The heat resistant low thermal conductive foam according to claim 1, wherein the 50% compression load is 50 N / cm ² or less.   The heat resistant low thermal conductive foam according to claim 1 or 2, having a dimensional change rate of less than ± 5% when stored at 125 ° C for 22 hours.   The heat resistant low thermal conductive foam according to any one of claims 1 to 3, wherein a 50% compression load change rate when stored at 125 ° C for 22 hours is ± 10% or less.   The heat-resistant low thermal conductive foam according to any one of claims 1 to 4, wherein the foam comprises a hydrophilic polyurethane-based polymer.   The heat resistant low thermal conductive foam according to any one of claims 1 to 5, wherein an average pore diameter of the spherical bubbles is less than 20 µm.   The heat resistant low thermal conductive foam according to any one of claims 1 to 6, wherein the foam has an open cell structure having a through hole between adjacent spherical bubbles.   The heat-resistant low thermal conductive foam according to claim 7, wherein an average pore diameter of the through holes is 5 µm or less. The heat resistant low thermal conductive foam according to any one of claims 1 to 8, wherein the density of the foam is 0.5 g / cm ³ or less.