JP5642456B2 - Foam with excellent toughness and heat resistance - Google Patents

Description

  The present invention relates to a foam excellent in toughness and heat resistance.

  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.

  Foams are conventionally wet coagulation method, dry transfer method, chemical foaming method using chemical foaming agent, thermally expandable plastic microballoon, physical foaming method using water dispersion of thermoplastic resin, thermoplasticity It is obtained by molding a foamed layer by a mechanical foaming method in which air is mixed with an aqueous resin dispersion (see, for example, Patent Documents 1 to 3).

  However, although the foam obtained by the wet coagulation method is a porous body, the pore size is not uniform in the thickness direction, and there is a problem that sufficient mechanical strength cannot be expressed. Further, there is a problem that a long time is required for wet solidification.

  In the composite sheet obtained by the dry transfer method and the composite sheet obtained by the mechanical foaming method in which air is mixed with an aqueous dispersion of a thermoplastic resin, the pore size is almost uniformly distributed in the thickness direction. However, since the holes are formed by the gas, it is difficult to control the hole diameter size, so that a hole having a large diameter may be generated, and there is a problem that sufficient mechanical strength cannot be expressed. Also, in the dry transfer method, it is necessary to use environmentally hazardous substances such as organic solvents in the manufacturing process. For environmental consideration, environmentally hazardous substances contained in the resin must be finally removed by heating and drying. There was a problem of not becoming.

  A foam obtained by a chemical foaming method using a chemical foaming agent and a foam obtained by a heat-expandable plastic microballoon are inevitably expensive because high temperature controllability is required in the production process. There is a problem that a large dedicated facility is required. Moreover, the foam obtained by the chemical foaming method using a chemical foaming agent, and the foam obtained by a thermally expansible plastic microballoon are 3-5 times the magnitude | size of the foam layer contained in it before a foaming process. There is a problem that sufficient mechanical strength cannot be achieved because the size and the diameter of the hole become large.

  When a foam is obtained by extrusion molding of a thermoplastic resin, there is a problem that the dimensional change is significant during heat storage, the cell structure is crushed by melting of the thermoplastic resin, etc., and sufficient heat resistance cannot be expressed (for example, patents) Reference 1).

Although the foam obtained by a physical foaming method using an aqueous dispersion of a thermoplastic resin is a microporous material, the density control range of the porous layer is 0.5 g / cm ^{3 to} 0.9 g / cm ^3. It is limited to a narrow range. Moreover, as a clearance at the time of application | coating of a water dispersion liquid, about 50 micrometers-600 micrometers are suitable, and since the thickness of a porous layer falls rather than before a process by volatilizing a water | moisture content, the control range of the thickness of a porous layer Is narrow (see, for example, Patent Document 3).

  On the other hand, the W / O type emulsion is particularly known as a W / O type HIPE (highly discontinuous phase emulsion) (see, for example, Patent Document 4), and a W / O type HIPE containing a polymerizable monomer in an external oil phase. It has been carried out to study the geometrical arrangement of the oil phase and the aqueous phase of the emulsion by forming a polymer. For example, by polymerizing after preparing a W / O type HIPE containing 90% aqueous phase component and using styrene monomer in the oil phase component, the geometry of the oil phase and aqueous phase of the emulsion can be reduced. It is reported to consider (for example, refer nonpatent literature 1). In Non-Patent Document 1, a W / O type HIPE is prepared by stirring an oil phase and an aqueous phase using a lipophilic emulsifier, and then the polymerization is performed, and the phase relationship of the precursor of the W / O type HIPE is determined. It has been reported that a rigid porous body having a determined bubble shape is formed.

  The physical properties of the porous body formed by polymerizing the W / O type emulsion depend on the type of components constituting the W / O type emulsion and the emulsification conditions when preparing the W / O type emulsion. .

  For example, a method for preparing an absorbent porous polymer from W / O type HIPE comprising at least 90 parts by weight of water and an oil phase comprising a polymerizable monomer, a surfactant and a polymerization catalyst has been reported. (For example, see Patent Document 5).

  By repeating washing and dehydration after polymerization for W / O type HIPE comprising at least an aqueous phase component and an oil phase component containing a polymerizable monomer, a surfactant and a polymerization catalyst, A method for preparing a hydrophobic porous body having a dry density of less than 100 mg / cc has been reported (for example, see Patent Document 6).

  For example, a method for producing a porous cross-linked polymer in which the process from the preparation of W / O type HIPE to the polymerization thereof is continuously reported (for example, see Patent Document 7).

  For example, a method for producing a foam by photopolymerizing W / O type HIPE has been reported (for example, see Patent Document 8).

  As described above, there are some known methods for producing a porous body from a W / O emulsion. However, there are several problems with such a porous body.

  For example, W / O type HIPE comprising a (meth) acrylic monomer, a polyfunctional (meth) acrylic monomer, and a lipophilic emulsifier such as sorbitan monooleic acid as a continuous oil phase component, or (meth) as a continuous oil phase component A method for producing a foam by photopolymerization using a W / O type HIPE comprising a lipophilic emulsifier such as an acrylic monomer, an aromatic urethane acrylate and sorbitan monooleic acid has been reported. However, a foam made of a crosslinked (meth) acrylic polymer is excellent in that it can be provided as a foam having a high cell ratio, but there is a problem that the uniformity of the cell structure is not sufficient, There is a problem that the toughness is inferior, for example, cracks are generated in the foam by a 180 ° bending test and a high compression test of 80% or more (see, for example, Patent Document 8).

  Even if the composition of the continuous oil phase of the W / O emulsion (for example, the monomer / crosslinking agent content, the amount of emulsifier and the type of emulsifier), the temperature during emulsification, the stirring conditions, etc. are changed only slightly, The emulsion state of the O-type emulsion is broken, and at least a part of them is clearly separated into an aqueous phase or an oil phase. For this reason, it is not easy to prepare a W / O emulsion suitable for obtaining the desired foam.

  That is, it has been extremely difficult to provide a foam having a uniform fine cell structure and excellent toughness and heat resistance.

JP 2001-9952 A JP 2001-38837 A International Publication Pamphlet 2002/101141 Specification US Pat. No. 3,565,817 Japanese Examined Patent Publication No. 3-66323 Special table 2003-514052 gazette Special table 2001-163904 gazette Japanese translation of PCT publication No. 2003-510390 "Medium and high discontinuous phase ratio water / polymer emulsion" (Lissant and Mahan, Journal of Colloid and Interfacescience, Vol. 42, No. 1, January 1973, pages 201-208)

  An object of the present invention is to provide a novel foam having a uniform fine cell structure and excellent in toughness and heat resistance.

The foam of the present invention is
A foam having spherical cells,
The average pore size of the spherical bubbles is less than 20 μm,
Density of foam is ^{0.15g / cm 3 ~0.9g / cm 3} ,
Cracks do not occur in the 180 ° bending test.

  In a preferred embodiment, the 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 foam of the present invention has a tensile strength change rate of less than ± 20% when stored at 125 ° C. for 14 days.

  In a preferred embodiment, the foam of the present invention has an open cell structure with through holes 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 foam of the present invention is a sheet-like foam sheet.

  According to the present invention, it is possible to provide a novel foam having a uniform fine cell structure and excellent in toughness and heat resistance.

  Since the foam of the present invention has a precisely controlled three-dimensional network structure, it can exhibit excellent heat resistance and excellent mechanical properties.

2 is a photograph of a cross-sectional SEM photograph of the foam obtained in Example 1. FIG. 6 is a photograph of a cross-sectional SEM photograph of the foam obtained in Example 2. FIG. 6 is a photograph of a cross-sectional SEM photograph of the foam obtained in Example 3. FIG. It is a photograph figure of the surface / cross-section SEM photograph which image | photographed the foam obtained in Example 4 from diagonally. It is a photograph figure of the surface / cross-section SEM photograph which image | photographed the foam obtained in Example 5 from diagonally. 4 is a photograph of a cross-sectional SEM photograph of a foam obtained in Comparative Example 1. FIG. 6 is a photograph of a cross-sectional SEM photograph of a foam obtained in Comparative Example 2. FIG. 6 is a photograph of a cross-sectional SEM photograph of a foam obtained in Comparative Example 3. FIG. It is a photograph figure of the section SEM photograph of the foam obtained in comparative example 4. It is a photograph figure of the section SEM photograph of the foam of the present invention, and is a photograph figure clearly showing the open-cell structure which has a penetration hole between adjacent spherical bubbles.

≪ << A. Foam >>>>
The foam of the present invention is a foam having spherical cells.

  In the present specification, the “spherical bubble” does not have to be a strict true spherical bubble, for example, a substantially spherical bubble having a partial strain or a bubble having a large strain. Also good.

  The average pore diameter of the spherical bubbles of the foam of the present invention is less than 20 μm, preferably 15 μm or less, and more preferably 10 μm or less. The lower limit value of the average pore diameter of the spherical bubbles of the foam of the present invention is not particularly limited. For example, it is preferably 0.01 μm, more preferably 0.1 μm, and further preferably 1 μm. When the average pore diameter of the spherical bubbles of the foam of the present invention falls within the above range, the average pore diameter of the spherical bubbles of the foam of the present invention can be precisely controlled to be small, and the novel has excellent toughness and heat resistance. A foam can be provided.

The density of the foam of the present invention ^{is 0.15g / cm 3 ~0.9g / cm 3} , preferably ^{0.15g / cm 3 ~0.7g / cm 3} , more preferably 0.15 g / cm ^{3 to} 0.5 g / cm ³ . By providing the density of the foam of the present invention within the above range, it is possible to provide a novel foam excellent in toughness and heat resistance while widely controlling the density range of the foam of the present invention. it can.

  The foam of the present invention may have an open cell structure having through holes between adjacent spherical cells. 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 foam. For example, the strength of the foam tends to increase as the average pore diameter of the through holes decreases. FIG. 10 is a photographic view of a cross-sectional SEM photograph of the foamed layer of the composite sheet of the present invention, and a photographic view clearly showing 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, a novel foam having excellent toughness and heat resistance can be provided.

  The foam of the present invention preferably has a surface opening.

  When the foam of the present invention has a surface opening, the average pore diameter of the surface opening is preferably 5 μm, more preferably 4 μm, and even more preferably 3 μm as an upper limit. 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. When the average pore diameter of the surface opening is within the above range, a novel foam having excellent toughness and heat resistance can be provided.

  The foam of the present invention does not generate cracks in a 180 ° bending test. This indicates that the foam of the present invention has very good toughness.

  The foam of the present invention has a dimensional change rate of preferably less than ± 5%, more preferably ± 3% or less, and even more preferably ± 1% or less when stored at 125 ° C. for 22 hours. In the foam of the present invention, the dimensional change rate when stored at 125 ° C. for 22 hours is within the above range, so that the foam of the present invention can have extremely excellent heat resistance.

  The foam of the present invention has a tensile strength change rate of preferably less than ± 20%, more preferably ± 18% or less when stored at 125 ° C. for 14 days. In the foam of the present invention, when the tensile strength change rate when stored at 125 ° C. for 14 days is within the above range, the foam of the present invention can have very excellent heat resistance.

  The foam of the present invention has a tensile strength of preferably 0.1 MPa or more, more preferably 0.15 MPa or more, and further preferably 0.2 MPa or more. When the tensile strength of the foam of the present invention falls within the above range, the foam of the present invention can have very excellent mechanical properties.

  The foam of the present invention has a 50% compression load of preferably 3000 kPa or less, more preferably 1000 kPa or less, and still more preferably 200 kPa or less. When the 50% compression load falls within the above range in the foam of the present invention, the foam of the present invention can have very excellent flexibility.

The material of the foam of the present invention is a foam having spherical bubbles, the average pore diameter of the spherical bubbles is less than 20 μm, and the density of the foam is 0.15 g / cm ^{3 to} 0.9 g / cm ^3. As long as no crack is generated in the 180 ° bending test, a foam of any appropriate material can be adopted.

  The foam of the present invention can take any suitable shape. Practically, preferably, the foam of the present invention is a sheet-like foam sheet. When the foam of the present invention is a foam sheet, the thickness, the length of the long side, and the length of the short side can take any appropriate value.

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

  As a method for producing the foam of the present invention, for example, a W / O emulsion that can be used to obtain a foam of the present invention by continuously supplying a continuous oil phase component and an aqueous phase component to an emulsifier is prepared. Subsequently, there is a “continuous method” in which the obtained W / O emulsion is polymerized to produce a water-containing polymer, and then the obtained water-containing polymer is dehydrated. As a method for producing the 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. A W / O emulsion that can be used to obtain the foam of the invention is prepared, and the resulting W / O emulsion is polymerized to produce a hydrous polymer, followed by dehydration of the hydrous polymer obtained. And “batch method”.

  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 foam of the present invention is preferably
Step (I) of preparing a W / O emulsion that can be used to obtain the 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 foam of the present invention is a W / O type emulsion containing a continuous oil phase component and an aqueous phase component 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 and the continuous oil phase component in the W / O type emulsion that can be used to obtain the foam of the present invention can be any suitable ratio within a range that can form a W / O type emulsion. . The ratio of the water phase component and the continuous oil phase component in the W / O emulsion that can be used to obtain the foam of the present invention is the structural ratio of the porous polymer material obtained by polymerization of the W / O emulsion. It can be an important factor in determining 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 foam of the present invention is a porous polymer obtained by polymerization of the W / O type emulsion. It can be an important factor in determining the material density, cell size, cell structure, and dimensions of the wall forming the porous structure.

  The ratio of the aqueous phase component in the W / O emulsion that can be used to obtain the foam of the present invention is preferably 30% by weight, more preferably 40% by weight, and even more preferably 50% as a lower limit. % 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 80% by weight. It is. If the ratio of the aqueous phase component in the W / O type emulsion that can be used to obtain the 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 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 foam of the present invention. As a method for producing a W / O type emulsion that can be used to obtain the foam of the present invention, for example, a continuous oil phase component and an aqueous phase component are continuously supplied to an emulsifier to produce a W / O type emulsion. A W / O type emulsion is formed by supplying an appropriate amount of water phase component to the “continuous process” or continuous oil phase component into an emulsifier and continuously supplying the water phase component while stirring. Examples include “batch method”.

  When producing a W / O emulsion that can be used to obtain the foam of the present invention, as a shearing means for obtaining an emulsion state, for example, a high shear using a rotor-stator mixer, a homogenizer, a microfluidizer, etc. Application of conditions is 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 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 contains polyoxyethylene polyoxypropylene units derived from polyoxyethylene polyoxypropylene glycol, and 5 wt% to 25 wt% in the polyoxyethylene polyoxypropylene units is polyoxyethylene. .

  The content ratio of the polyoxyethylene in the polyoxyethylene polyoxypropylene unit is 5 to 25% by weight as described above, and the lower limit is preferably 10% by weight, more preferably 15% by weight. The upper limit is preferably 25% by weight, 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 type emulsion that can be used to obtain the foam of the present invention has a characteristic structure as described above. When it is included in the continuous oil phase component of the type emulsion, excellent emulsifiability 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 amount of residual diisocyanate compound increases, and the W / O emulsion that can be used to obtain the foam of the present invention may be unstable.

  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 Examples include (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and isostearyl (meth) acrylate. Among these, n-butyl (meth) acrylate and 2-ethylhexyl (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. If 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 porous material may increase. is there. 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 porous material may be reduced.

  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, before the light irradiation, it is preferable that an inert gas such as nitrogen is blown into the reaction system and oxygen is replaced with an inert gas or deaerated by a reduced pressure treatment.

(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 choice of the type and content of the cross-linking agent depends on the structural properties, mechanical properties, and fluid treatment properties desired for the resulting porous material. The selection of the specific type and content of the cross-linking agent is important in achieving the desired combination of structural properties, mechanical properties, and fluid treatment properties of the porous material.

  In producing the 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 foam of the present invention, more preferably, the crosslinking agent is 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”. “One or more” and “one or more selected from polyfunctional (meth) acrylate and polyfunctional (meth) acrylamide 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 hexane-diol, 1,4-butanediol, 1,3-butanediol, 1,4 butane-2-enedi It can be derived from all, ethylene glycol, diethylene glycol, trimethylolpropane, pentaerythritol, hydroquinone, catechol, resorcinol, triethylene glycol, polyethylene glycol, sorbitol, polypropylene glycol, polytetramethylene glycol, bisphenol A propylene oxide modified product, 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 30% 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 30% by weight based on the total amount of coalesced and ethylenically unsaturated monomer, the cohesive strength of the resulting foam may be reduced, and it may be difficult to achieve both toughness and flexibility. . 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 weight% with respect to the total amount of a coalescence and an ethylenically unsaturated monomer, the emulsion stability of a W / O type emulsion will fall, and there exists a possibility that a desired 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 foam obtained may fall and there exists a possibility of showing 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 size of the obtained foam may be non-uniform or the strength of the 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, ultraviolet irradiation in each step is performed in a plurality of stages, and thereby the efficiency of the polymerization reaction can be precisely adjusted.

  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, the foam of the present invention is 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.

  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

(Standing storage stability of emulsion)
About 30 g of the prepared W / O type emulsion was weighed into a container with a capacity of 50 ml, and the generation of free water immediately after the preparation was observed to evaluate the storage stability at room temperature.
○: No free water after 24 hours Δ: Slightly free water generated by 1 hour ×: Free water generated by 1 hour

(Measurement of average pore diameter)
A sample for measurement was prepared by cutting the produced foam sheet in the thickness direction with a microtome cutter. The cut surface of the sample for measurement was photographed with a low vacuum scanning electron microscope (Hitachi, S-3400N) at a magnification of 800 to 5000 times. Using the obtained image, the major axis lengths of up to about 30 large-sized spherical bubbles, through-holes and surface openings were measured, and the average value of the measured values was taken as the average pore diameter.

(Porosity dispersion)
A sample for measurement was prepared by cutting the produced foam sheet in the thickness direction with a microtome cutter. The cut surface of the sample for measurement was photographed with a low vacuum scanning electron microscope (Hitachi, S-3400N) at a magnification of 800 to 5000 times. Using the obtained image, the major axis lengths of up to about 30 large-sized spherical bubbles, through holes and surface openings were measured, and the average value of the measured values was taken as the average pore diameter. The degree of dispersion of the pore diameters of the spherical bubbles, the through holes, and the surface openings was calculated by Equation 1 using the obtained average pore diameter values.
Dispersity = total of ((data−average value) squared) ÷ number of units ··· Equation 1

(Standard deviation of pore diameter)
A sample for measurement was prepared by cutting the produced foam sheet in the thickness direction with a microtome cutter. The cut surface of the sample for measurement was photographed with a low vacuum scanning electron microscope (Hitachi, S-3400N) at a magnification of 800 to 5000 times. Using the obtained image, the major axis lengths of up to about 30 large-sized spherical bubbles, through holes and surface openings were measured, and the average value of the measured values was taken as the average pore diameter. The standard deviation of the respective pore diameters of the spherical bubbles, the through holes, and the surface openings was calculated by Formula 2 using the degree of dispersion calculated from the average pore diameter value.
Standard deviation = square root of (dispersion) ··· Equation 2

(Measurement of density of foam)
Five pieces of the produced 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 50% compression load)
The 50% compression load of the produced foam was measured based on the compression load test of JIS-K-6767. The value obtained when the test piece was compressed to 50% under the condition of a compression speed of 10 mm / min was taken as the value of 50% compression load.

(Measurement of tensile strength)
The tensile strength of the produced foam was measured at a tensile speed of 50 mm / min according to JIS-K-7113.

(Measurement of rate of change in tensile strength)
After the produced foam was stored in an oven at 125 ° C. for 14 days, the tensile strength was measured at a tensile rate of 50 mm / min according to JIS-K-7113, and the tensile strength before and after the heat storage treatment was measured. The rate of change was determined.

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

(180 ° bending test)
The produced foam was cut into 100 mm × 100 mm in the longitudinal direction (MD: Machine Direction) or transverse direction (TD: Transverse Direction) to obtain a measurement sample. After the end of the measurement sample was bent at about 50 mm and bent by 180 ° in the longitudinal direction, the ends were overlapped, and then moved back and forth from the overlapped end to the bending point with a 1 kg roller. The occurrence of cracks at the bending point was visually confirmed. Samples were measured at n = 3.

[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, 1.5 parts by weight of methanol (manufactured by Kishida Chemical Co., Ltd., special grade) was added dropwise and reacted at 65 ° C. for 2 hours to obtain a hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup. The weight average molecular weight of the obtained hydrophilic polyurethane polymer was 15,000. 48 parts by weight of 2EHA with respect to 100 parts by weight of the obtained hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup, acrylic acid (manufactured by Toa Gosei Co., Ltd., hereinafter abbreviated as “AA”) 12 parts by weight A hydrophilic polyurethane-based polymer / ethylenically unsaturated monomer mixed syrup 1 was added.

[Production Example 2]: Preparation of mixed syrup 2 In the preparation of syrup 1 in Production Example 1, polyoxyethylene polyoxypropylene glycol and DBTL were charged into 2EHA, and HXDI was added dropwise with stirring to 4 ° C at 4 ° C. After reacting for 2 hours, 5.6 parts by weight of 2-hydroxyethyl acrylate (manufactured by Kishida Chemical Co., Ltd., hereinafter abbreviated as “HEA”) was added dropwise instead of methanol, and reacted at 65 ° C. for 2 hours. A hydrophilic polyurethane-based polymer / ethylenically unsaturated monomer mixed syrup having an acryloyl group was obtained. The weight average molecular weight of the obtained hydrophilic polyurethane polymer having acryloyl groups at both ends was 15,000. 48 parts by weight of 2EHA and 12 parts by weight of AA as a polar monomer are added to 100 parts by weight of a hydrophilic polyurethane-based polymer / ethylenically unsaturated monomer mixed syrup having acryloyl groups at both ends to obtain a hydrophilic polyurethane system. A polymer / ethylenically unsaturated monomer mixed syrup 2 was obtained.

[Production Example 3]: Preparation of mixed monomer 1 20 parts by weight of sorbitan monooleate (trade name “Leodol SP-O10V” manufactured by Kao Corporation), 72 parts by weight of 2EHA, and 8 parts by weight of AA until uniform The mixture was sufficiently mixed and stirred to obtain mixed monomer 1.

[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) 10 parts by weight, a reactive oligomer of polyurethane synthesized from polytetramethylene glycol (hereinafter abbreviated as" PTMG ") and isophorone diisocyanate (hereinafter abbreviated as" IPDI ") Both ends treated with HEA, urethane acrylate having ethylenically unsaturated groups at both ends (hereinafter abbreviated as “UA”) (molecular weight 3720), 56 parts by weight, diphenyl (2,4,6-trimethylbenzoyl) phos Fin oxide (BASF, trade name "Lucirin TPO") 0.5 parts by weight, hindered pheno Le-based antioxidant (manufactured by Ciba Japan, trade name "Irganox 1010") 1.0 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 foam (1) having a thickness of about 1 mm.
The results are shown in Table 1.
Moreover, the photograph figure of the cross-sectional SEM photograph of the obtained foam was shown in FIG.

[Example 2]
In Example 1, instead of the hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup 1 obtained in Production Example 1, the hydrophilic polyurethane polymer / ethylenically unsaturated monomer obtained in Production Example 2 was used. A stable W / O emulsion was prepared in the same manner as in Example 1 except that the mixed syrup 2 was used. The weight ratio of the water phase to the oil phase was 75/25.
Next, as in Example 1, a foam (2) having a thickness of about 1 mm was obtained.
The results are shown in Table 1.
Moreover, the photograph figure of the cross-sectional SEM photograph of the obtained foam was shown in FIG.

Example 3
In Example 2, a stable W / O emulsion was prepared in the same manner as in Example 2 except that 122 parts by weight of ion-exchanged water was continuously added dropwise at room temperature as an aqueous phase. The weight ratio of water phase to oil phase was 55/45.
Next, as in Example 1, a foam (3) having a thickness of about 1 mm was obtained.
The results are shown in Table 1.
Moreover, the photograph figure of the cross-sectional SEM photograph of the obtained foam was shown in FIG.

Example 4
In Example 2, a stable W / O emulsion was prepared in the same manner as in Example 2 except that 567 parts by weight of ion-exchanged water was continuously added dropwise at room temperature as an aqueous phase. The weight ratio of the water phase to the oil phase was 85/15.
Next, as in Example 1, a foam (4) having a thickness of about 1 mm was obtained.
The results are shown in Table 1.
Moreover, the photograph figure of the surface / cross-section SEM photograph which image | photographed the obtained foam from the diagonal was shown in FIG.

Example 5
In Example 2, instead of urethane acrylate, bisphenol A propylene oxide modified diacrylate (manufactured by Hitachi Chemical Co., Ltd., trade name “Fancryl FA-P321A”) (molecular weight 898) was used, as in Example 2. To prepare a stable W / O emulsion. The weight ratio of the water phase to the oil phase was 75/25.
Next, as in Example 1, a foam (5) having a thickness of about 1 mm was obtained.
The results are shown in Table 1.
Moreover, the photograph figure of the surface / cross-section SEM photograph which image | photographed the obtained foam from the diagonal was shown in FIG.

[Comparative Example 1]
In Example 1, Example 1 was used except that the mixed monomer 1 obtained in Production Example 3 was used in place of the hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup 1 obtained in Production Example 1. In the same manner as described above, a W / O type emulsion was prepared. In addition, generation | occurrence | production of the free water was confirmed during the emulsification process. The weight ratio of the water phase to the oil phase was 75/25.
Next, the obtained W / O emulsion was carried out in the same manner as in Example 1 except that the free water on the emulsion surface that could be visually confirmed was removed immediately before molding, and a foam (C1) having a thickness of about 700 μm. )
The results are shown in Table 2.
Moreover, the photograph figure of the cross-sectional SEM photograph of the obtained foam was shown in FIG.

[Comparative Example 2]
Comparative Example 1 was the same as Comparative Example 1 except that bisphenol A propylene oxide-modified diacrylate (manufactured by Hitachi Chemical Co., Ltd., trade name “Fancryl FA-P321A”) (molecular weight 898) was used instead of urethane acrylate. To prepare a W / O emulsion. The weight ratio of the water phase to the oil phase was 75/25. The generation of free water was confirmed 30 minutes after the emulsion preparation.
Next, the obtained W / O emulsion was carried out in the same manner as in Example 1 except that the free water on the emulsion surface that could be visually confirmed was removed immediately before molding, and a foam (C2) having a thickness of about 1 mm. )
The results are shown in Table 2.
Moreover, the photograph figure of the cross-sectional SEM photograph of the obtained foam was shown in FIG.

[Comparative Example 3]
A W / O emulsion was prepared in the same manner as in Example 2 except that NK ester A-HD-N was not used and 20 parts by weight of UA as a reactive oligomer was used. . The weight ratio of the water phase to the oil phase was 75/25.
Next, in the same manner as in Example 1, after obtaining a highly water-containing crosslinked polymer having a thickness of about 1 mm, the whole foam was contracted by heating at 130 ° C. for 20 minutes, and the cell structure was A partially collapsed foam (C3) having a thickness of about 300 μm was obtained.
The results are shown in Table 2.
Moreover, the photograph figure of the cross-sectional SEM photograph of the obtained foam was shown in FIG.

[Comparative Example 4]
A W / O emulsion was prepared in the same manner as in Example 2 except that 40 parts by weight of NK ester A-HD-N was used and UA as a reactive oligomer was not used. The weight ratio of the water phase to the oil phase was 75/25.
Next, in the same manner as in Example 1, a foam (C4) having a thickness of about 1 mm was obtained.
The results are shown in Table 2.
Moreover, the photograph figure of the cross-sectional SEM photograph of the obtained foam was shown in FIG.

  The foam of the present invention is suitable for countless applications including cushion materials, insulation, heat insulation materials, soundproof materials, dustproof materials, filter materials, reflective materials, and the like.

Claims (6)

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, an ethylenically unsaturated monomer, and a crosslinking agent,
The crosslinking agent is at least two kinds of crosslinking agents having different weight average molecular weights,
The average pore size of the spherical bubbles is less than 20 μm,
Density of foam is ^{0.15g / cm 3 ~0.9g / cm 3} ,
Cracks do not occur in the 180 ° bending test,
Foam.   The foam of Claim 1 whose dimensional change rate when preserve | saved at 125 degreeC for 14 days is less than +/- 5%.   The foam of Claim 1 or 2 whose tensile strength change rate when preserve | saved at 125 degreeC for 14 days is less than +/- 20%.   The foam according to any one of claims 1 to 3, which has an open-cell structure having a through-hole between adjacent spherical bubbles.   The foam of Claim 4 whose average hole diameter of the said through-hole is 5 micrometers or less. The foam according to any one of claims 1 to 5, which is a sheet-like foam sheet.