JP5877656B2 - Foam sheet - Google Patents

Description

  The present invention relates to a foam sheet. In detail, it is related with the novel foam sheet which can express the outstanding softness | flexibility and the outstanding water repellency.

  The foam sheet is composed of a water absorbing material, a water retaining material, a cushion material, a heat insulating material, a sound absorbing material, a separation film, a reflective material, various substrates such as a circuit board, a holding member such as a printing plate, a supporting member, a polishing pad for a polishing process It is widely used in various applications such as a surface plate for supporting it, a support base used for holding or transporting a semiconductor, various substrates, etc. from the back surface by vacuuming or the like.

  In recent years, some of the applications described above are often required to have excellent water repellency.

  As a foam sheet excellent in water repellency, a water-repellent polyurethane foam obtained by molding a polyurethane raw material containing a specific polyol component, polyisocyanate component, foaming agent and catalyst has been reported (see Patent Documents 1 and 2). ).

  However, the foam sheets reported in Patent Documents 1 and 2 do not have sufficient flexibility and do not have a sufficient level of water repellency.

JP 2007-314672 A JP 2007-314666 A

  The subject of this invention is providing the novel foam sheet which can express the outstanding softness | flexibility and the outstanding water repellency.

The foam sheet of the present invention is
A foam sheet comprising a foam having an open cell structure having a through-hole between adjacent spherical cells,
The foam includes a hydrophilic polyurethane-based polymer,
The water absorption is 1.0 times or less,
The shear adhesive strength is 1 N / cm ² or more.

  In a preferred embodiment, the foam sheet of the present invention is provided with a water repellent layer on at least one surface side.

  In a preferred embodiment, the surface of the foam has a surface opening having an average pore diameter of 20 μm or less.

  In a preferred embodiment, a water repellent layer is provided on at least a part of the hole inner wall of the surface opening.

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

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

In a preferred embodiment, the foam has a density in the ^{0.15g / cm 3 ~0.6g / cm 3} .

  In a preferred embodiment, the foam ratio of the foam is 30% or more.

In a preferred embodiment, the foam sheet of the present invention has a 50% compression load of 300 N / cm ² or less.

In a preferred embodiment, the foam sheet of the present invention comprises
It is obtained by polymerizing and dehydrating a W / O emulsion containing a continuous oil phase component and an aqueous phase component immiscible with the continuous oil phase component,
The continuous oil phase component includes a hydrophilic polyurethane polymer and an ethylenically unsaturated monomer,
The hydrophilic polyurethane-based polymer includes a polyoxyethylene polyoxypropylene unit derived from polyoxyethylene polyoxypropylene glycol,
5 to 25% by weight of the polyoxyethylene polyoxypropylene unit is polyoxyethylene.

  ADVANTAGE OF THE INVENTION According to this invention, the novel foam sheet which can express the outstanding softness | flexibility and the outstanding water repellency can be provided.

It is a schematic sectional drawing which shows preferable embodiment of the foam sheet of this invention. It is a schematic sectional drawing which shows another preferable embodiment of the foam sheet of this invention. It is a photograph figure of the surface / cross-section SEM photograph which image | photographed the foam sheet before performing the water-repellent process in Example 1 from diagonally. It is a photograph of the cross-sectional SEM photograph of the foam sheet of this invention before performing a water repellent process, Comprising: It is a photograph figure showing clearly the open-cell structure which has a through-hole between adjacent spherical bubbles.

≪ << A. Foam sheet >>>>
The foam sheet of the present invention is a foam sheet including a foam having an open cell structure having through holes between adjacent spherical cells. Typical structures include a foam sheet 100 (FIG. 1) made of the foam 10 and a foam sheet 100 (FIG. 2) including a base material 20 (described later) between the foam 10a and the foam 10b. Can be mentioned. In FIG. 1 and FIG. 2, the release film 30 is provided for protecting the adhesive surface of the foam sheet, but the release film may not be provided. The foam sheet of the present invention is preferably provided with a water repellent layer on at least one surface side.

  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 contained in the foam contained in the foam sheet of the present invention is preferably less than 20 μm, more preferably 15 μm or less, and even 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 foam sheet 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. It is. When the average pore diameter of the spherical bubbles contained in the foam contained in the foam sheet of the present invention falls within the above range, the average pore diameter of the spherical bubbles in the foam contained in the foam sheet of the present invention can be precisely controlled to be small. A novel foam sheet excellent in flexibility and water repellency can be provided.

Density of the foam contained in the foam sheet of the present invention is preferably ^{0.15g / cm 3 ~0.6g / cm 3} , more preferably 0.15g ^/ cm ³ ~0.5g ^/ cm 3 There, more preferably ^{0.15g / cm 3 ~0.45g / cm 3} , particularly preferably from ^{0.15g / cm 3 ~0.4g / cm 3} . When the density of the foam contained in the foam sheet of the present invention falls within the above range, the range of the density of the foam contained in the foam sheet of the present invention is widely controlled, and the flexibility and water repellency are improved. An excellent and novel foam sheet can be provided.

  The foam contained in the foam sheet of the present invention has 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 sheet. For example, the strength of the foam sheet tends to increase as the average hole diameter of the through holes decreases. FIG. 4 is a photograph of a cross-sectional SEM photograph of the foam sheet of the present invention before performing the water repellent treatment, and shows a photograph 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 sheet excellent in flexibility and water repellency can be provided.

  The foam sheet of the present invention 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. To provide a novel foam sheet excellent in flexibility and water repellency by having the foam sheet of the present invention has a surface opening and the average pore diameter of the surface opening is within the above range. Can do. In a preferred embodiment, a water repellent layer is provided on at least a part of the hole inner wall of such a surface opening.

The foam sheet of the present invention has a shear adhesive strength of 1 N / cm ² or more, preferably 3 N / cm ² or more, more preferably 5 N / cm ² or more, and further preferably 7 N / cm ² or more. It is particularly preferably 9 N / cm ² or more, and most preferably 10 N / cm ² or more. When the shear adhesive force of the foam sheet of the present invention falls within the above range, the foam sheet of the present invention can exhibit a sufficient adhesive force.

The foam sheet of the present invention has a 50% compression load of preferably 300 N / cm ² or less, more preferably 150 N / cm ² or less, still more preferably 100 N / cm ² or less, and particularly preferably 70 N. / Cm ² or less, and most preferably 50 N / cm ² or less. When the 50% compressive load of the foam sheet of the present invention falls within the above range, the foam sheet of the present invention can exhibit excellent flexibility.

The foam sheet of the present invention has a water absorption defined by the following formula of 1.0 times or less, preferably 0.5 times or less, more preferably 0.3 times or less, and still more preferably It is 0.2 times or less, and particularly preferably 0.1 times or less. When the water absorption rate falls within the above range in the foam sheet of the present invention, the foam sheet of the present invention can have excellent water repellency.
Water absorption rate (times) = (W1-W0) / W0
W0: Initial weight of sample punched to 25 mm × 25 mm.
W1: The weight measured after 10 minutes after the sample in which W0 was measured was left for 24 hours in a state of being completely immersed in ion-exchanged water and then taken out.

  The foam contained in the foam sheet of the present invention has a cell ratio of preferably 30% or more, more preferably 40% or more, and further preferably 50% or more. In the foam sheet of the present invention, by providing the foam ratio of the foam contained in the foam sheet of the present invention within the above range, a novel foam sheet excellent in flexibility and water repellency can be provided. it can.

The foam material contained in the foam sheet of the present invention is a foam sheet including a foam having an open cell structure having through-holes between adjacent spherical cells, wherein the foam is a hydrophilic polyurethane-based polymer. Any suitable material can be adopted as long as it includes coalescence, has a water absorption rate of 1.0 times or less, and has a shear adhesive strength of 1 N / cm ² or more.

  Any appropriate layer can be adopted as the water-repellent layer that can be included in the foam sheet of the present invention as long as the layer can exhibit water repellency.

  The water repellent layer preferably contains a water repellent compound. The content ratio of the water repellent compound in the water repellent layer is preferably 0.01 to 100% by weight, more preferably 0.01 to 90% by weight, and still more preferably 0.01 to 80% by weight. .

  Any appropriate water-repellent compound can be adopted as the water-repellent compound. Examples of such a water repellent compound include at least one selected from a silicone compound and a fluorine compound.

  Examples of the silicone compound include silicone compounds that can be used as a water repellent. Examples of such silicon compounds include resins having a main skeleton having a siloxane bond. Specific examples of the silicone compound include dimethylpolysiloxane, methylhydropolysiloxane, silicone oil, silicone varnish, and a silicone-modified acrylic copolymer disclosed in JP-A-9-111185.

  Examples of the fluorine-based compound include fluorine-based compounds that can be used as a water repellent. Examples of such a fluorine-based compound include a compound having a fluorine-containing chain and a resin obtained by polymerizing a fluorine-containing olefin. Specific examples of the fluorine compound include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene / hexafluoropropylene copolymer, chlorofluoroethylene / vinylidene fluoride, and the like. A copolymer etc. are mentioned.

  The water repellent compound in the water repellent layer may be only one type or two or more types.

  The water repellent layer may further contain any appropriate additive depending on the purpose.

  Examples of the additive include a photopolymerization initiator, a silane coupling agent, a release agent, a curing agent, a curing accelerator, a diluent, an anti-aging agent, a denaturing agent, a surfactant, a dye, a pigment, and a discoloration preventing agent. UV absorbers, softeners, stabilizers, plasticizers, antifoaming agents and the like. The type, number, and amount of additives that can be contained in the water repellent layer can be appropriately set according to the purpose.

  The water repellent layer may be provided on at least one surface side of the foam sheet of the present invention. Preferably, the water repellent layer may be provided on at least a part of the hole inner wall of the surface opening. The water repellent layer may consist of only one layer or may consist of two or more layers.

  The thickness of the water repellent layer is preferably 1 to 500 nm, more preferably 1 to 100 nm. If the thickness of the water repellent layer is within the above range, excellent water repellency can be expressed without impairing the flexibility of the foam sheet of the present invention.

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

  The foam sheet 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 foam sheet of the present invention include a form in which a base material layer is provided inside the foam sheet. 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. Arbitrary appropriate thickness can be employ | adopted for the thickness of a base material according to material and the objective.

  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 foam sheet of the present invention, when voids are present in the substrate, the same material as the foam sheet may be present in a 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 foam sheet >>>>
The foam sheet of the present invention can be produced by any suitable method. The foam sheet of the present invention can be preferably produced by shaping and polymerizing a W / O emulsion.

  As a method for producing the foam sheet of the present invention, for example, a W / O type emulsion that can be used to obtain a foam sheet of the present invention by continuously supplying a continuous oil phase component and an aqueous phase component to an emulsifier. There is a “continuous method” in which the prepared 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 sheet of the present invention, for example, an appropriate amount of an aqueous phase component is charged into an emulsifier with respect to the continuous oil phase component, and the aqueous phase component is continuously supplied while stirring. A W / O type emulsion that can be used for obtaining the foam sheet of the present invention is prepared, and the obtained W / O type emulsion is polymerized to produce a hydrous polymer. The “batch method” is used for dehydration.

  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 sheet of the present invention is preferably,
A step (I) of preparing a W / O emulsion that can be used to obtain the foam sheet 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 sheet 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.

  In the W / O type emulsion that can be used to obtain the foam sheet of the present invention, the ratio of the water phase component and the continuous oil phase component is any suitable ratio within a range that can form the W / O type emulsion. obtain. In the W / O type emulsion that can be used to obtain the foam sheet of the present invention, the ratio of the water phase component to the continuous oil phase component is the structural and mechanical properties of the foam obtained by polymerization of the W / O type emulsion. Can be an important factor in determining performance 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 sheet of the present invention is the foam obtained by polymerization of the W / O type emulsion. Can be an important factor in determining the density, bubble size, bubble 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 sheet of the present invention is preferably 30% by weight, more preferably 40% by weight, and still more preferably as the lower limit. It is 50% by weight, particularly preferably 55% by weight, and the upper limit is preferably 98% by weight, more preferably 95% by weight, and still more preferably 90% by weight. If the ratio of the aqueous phase component in the W / O emulsion that can be used to obtain the foam sheet 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 sheet of the present invention can 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 type emulsion that can be used to obtain the foam sheet of the present invention. As a method for producing a W / O type emulsion that can be used for obtaining the foam sheet 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 aqueous phase component to the continuous oil phase component in an emulsifier and continuously supplying the aqueous phase component while stirring. The “batch method” is used.

  When producing a W / O type emulsion that can be used to obtain the foam sheet 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 shearing conditions 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 polymer contained in the continuous oil phase component of the W / O type emulsion that can be used to obtain the foam sheet of the present invention has a characteristic structure as described above. When included in the continuous oil phase component of the O-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 residual diisocyanate compound increases, and the W / O emulsion that can be used to obtain the foam sheet of the present invention may become 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-based photopolymerization initiators such as Irgacure-651) and 2-hydroxy-2-cyclohexylacetophenone (for example, Ciba Japan, trade name; Irgacure-184); 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 monomer in the resulting foam sheet may increase. is there. When the content ratio of the polymerization initiator exceeds 5.0% by weight with respect to the entire continuous oil phase component, the mechanical properties of the obtained foam sheet 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, 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 foam sheet. 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 foam sheet.

  In producing the foam sheet 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 sheet of the present invention, more preferably, the cross-linking agent is selected from “polyfunctional (meth) acrylate having a weight average molecular weight of 800 or more, polyfunctional (meth) acrylamide, and polymerization reactive oligomer”. "One or more selected from polyfunctional (meth) acrylates having a weight average molecular weight of 500 or less and polyfunctional (meth) acrylamide" 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 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 When the amount is less than 40% by weight based on the total amount of the coalesced and ethylenically unsaturated monomer, the cohesive force of the resulting foam sheet may be reduced, and it may be difficult to achieve both toughness and flexibility. is there. 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 sheet 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 water repellency is lowered, and the cell structure may be crushed by shrinkage 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 sheet 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 sheet may be nonuniform, and the strength of the foam sheet 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, the foam contained in the foam sheet of the present invention is obtained. The obtained foam can become the foam sheet of the present invention as it is. Moreover, it can become the foam sheet of this invention by combining with a base material so that it may mention later.

  Any appropriate drying method may be employed as the dehydration method in step (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 foam sheet of the present invention contains a base material >>
When the foam sheet of the present invention contains a substrate, as one of the preferred embodiments of the method for producing the foam sheet of the present invention, a W / O emulsion is coated on one surface of the substrate, and an inert gas is used. In the atmosphere or with a UV transparent film coated with a release agent such as silicone, the W / O emulsion is polymerized by heating or irradiating active energy rays in a state where oxygen is blocked. A form of a foam sheet having a base / foamed layer laminated structure is obtained by dehydrating the obtained hydropolymer as a coalescence.

  As another preferred embodiment of the method for producing a foam sheet of the present invention, two sheets of W / O type emulsions coated on one side of a UV transparent film coated with a release agent such as silicone were prepared. A base material is laminated on the application surface of one of the two W / O emulsion coating sheets, and another W / O emulsion coating sheet is formed on the other surface of the laminated base material. In a state in which the coated surfaces are laminated so as to match with each other, heating or irradiation with active energy rays is performed to polymerize the W / O emulsion to form a water-containing polymer, and the resulting water-containing polymer is dehydrated to obtain a foam layer. Examples include a foam sheet having a laminated structure of / substrate / foamed 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.

<< B-6. Water repellent layer >>
When the foam sheet of the present invention has a water repellent layer, the water repellent layer can be formed by any appropriate method. The water repellent layer may be provided on at least one surface side of the foam sheet of the present invention. Preferably, the water repellent layer may be provided on at least a part of the hole inner wall of the surface opening.

  The water repellent layer is preferably <<<< A. It can be formed by applying a water repellent layer forming material containing the water repellent compound described in the section of the foam sheet >>>> to the surface of the foam sheet. Examples of the water repellent layer forming material include commercially available water repellent treatment agents. Examples of the method for applying the water repellent layer forming material include dip, spray gun, spin coating and the like.

  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)
A sample for measurement was prepared by cutting the prepared composite sheet with a microtome cutter in the thickness direction. 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 arbitrary ranges of spherical bubbles, and the diameter of a 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 shear adhesive strength)
The obtained foam sheet was cut into 20 mm × 20 mm, and BA plates (SUS304) were attached to both surfaces of the foam sheet. A 2 kg roller was reciprocated once to press the sample placed horizontally. After crimping, the sample was left at room temperature overnight, fixed to Tensilon so that the sample was vertical at room temperature, pulled at a pulling rate of 50 mm / min, and the shear adhesive force was measured. Samples were measured at n = 2, and the average value was taken as the shear adhesive strength.

(Measurement of 50% compression load)
After laminating 10 sheets of the obtained foam sheet, it was cut into 20 mm × 20 mm to obtain a measurement sample. Tensilon was used for the measurement. 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 density of foam sheet)
Five sheets of the obtained foam sheet were cut into a size of 100 mm × 100 mm to form 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 sheet.

(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 sheet. The cell ratio of the foam sheet was calculated by the following equation using the relative density obtained by dividing the density of the foam sheet by the density of the resin component.
Bubble ratio = (1−relative density) × 100

(Measurement of water absorption)
The obtained foam sheet was punched out to 25 mm × 25 mm to obtain a sample, and the initial sample weight (W0) was measured. The sample in which W0 was measured was left for 24 hours in a state of being completely immersed in ion-exchanged water, and after taking it out, the moisture adhering to the foam sheet surface was wiped off, and the sample weight (W1) after 10 minutes was measured. And the water absorption was calculated according to the following formula.
Water absorption rate (times) = (W1-W0) / W0
W0: Initial weight of sample punched to 25 mm × 25 mm.
W1: The weight measured after 10 minutes after the sample in which W0 was measured was left for 24 hours in a state of being completely immersed in ion-exchanged water and then taken out.

(Underwater shear adhesion test (underwater creep measurement))
The obtained foam sheet was punched out to 25 mm × 50 mm to obtain a sample. After peeling off one separator of the sample and sticking it to the SUS plate, reciprocating the 2 kg roller once and pressing it, and peeling off the other separator and sticking the SUS plate, pressing the two kg roller once and then pressing, A load of 500 g was applied to one SUS plate and immersed in a water bath. The water level in the aquarium was 25 cm high (from the bottom) and the center of the weight was 7 cm high (from the bottom). The peeling time of the SUS plate-foam sheet after the immersion was measured and used as the measured value of underwater creep.

[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 And 100 parts by weight of a monomer solution consisting of Adeka (registered trademark) Pluronic L-62 (molecular weight 2500, manufactured by ADEKA Corporation, polyether polyol) as polyoxyethylene polyoxypropylene glycol, As a urethane reaction catalyst, 0.00832 parts by weight of dibutyltin dilaurate (manufactured by Kishida Chemical Co., Ltd., hereinafter abbreviated as “DBTL”) is added, and hydrogenated xylylene diisocyanate (Takeda Pharmaceutical Co., Ltd., Takenate) while stirring. 600, hereinafter abbreviated as “HXDI”) 7.02 parts by weight was added dropwise and reacted at 65 ° C. for 4 hours. I let you. In addition, the usage-amount of the polyisocyanate component and the polyol component was NCO / OH (equivalent ratio) = 1.6. Thereafter, 3.15 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 1 (solid content: 40% by weight) was obtained. The weight average molecular weight of the obtained hydrophilic polyurethane polymer was 15,000.

[Example 1]
To 67.7 parts by weight (19.1 parts by weight of solid content) of the hydrophilic polyurethane polymer / ethylenically unsaturated monomer mixed syrup 1 obtained in Production Example 1, 1,6-hexanediol diacrylate (new Nakamura Chemical Co., Ltd., trade name “NK Ester A-HD-N”) (molecular weight 226) 11.9 parts by weight, as reactive oligomer, polytetramethylene glycol (hereinafter abbreviated as “PTMG”) and isophorone diisocyanate ( Hereafter, both ends of a polyurethane synthesized from “IPDI”) are treated with HEA, and urethane acrylate having an ethylenically unsaturated group at both ends (hereinafter abbreviated as “UA”) (molecular weight 3720, dilution monomer) 2EHA, solid content 80% by weight) 59.7 parts by weight (solid content 47.7 parts by weight), diphenyl (2,4,6-trimethylben) Il) Phosphine oxide (BASF, trade name “Lucirin TPO”) 0.5 parts by weight, hindered phenolic antioxidant (Ciba Japan, trade name “Irganox 1010”) 1.0 part by weight As an ethylenically unsaturated monomer for adjusting the oil layer amount, 8.5 parts by weight of isobornyl acrylate (hereinafter abbreviated as “IBXA”), 26.7 parts by weight of butyl acrylate (hereinafter abbreviated as “BA”), acrylic acid ( Hereinafter, 5.1 parts by weight of “AA”) was uniformly mixed to obtain a continuous oil phase component (hereinafter referred to as “oil phase”).
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 foamed layer after light irradiation was prepared on a polyethylene terephthalate film (hereinafter referred to as “PET film”) having a thickness of 38 μm, and a W / O emulsion that had been stored at room temperature for 30 minutes by standing. The film was applied so as to have a thickness of 150 μm and continuously formed into a sheet shape. Furthermore, a 70 μm thick polyester fiber laminated fabric (trade name “Milife (registered trademark) TY1010E” manufactured by Nisshi Plast Co., Ltd.) in which stretched polyester long fibers were laminated in a vertical arrangement was laminated. Further, separately from the preparation, the W / O type emulsion, which was stored at room temperature for 30 minutes, was placed on a PET film having a thickness of 38 μm, and the foamed layer after light irradiation had a thickness of 150 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 500 μm. . Next, the top film was peeled off, and the highly hydrous crosslinked polymer was heated at 130 ° C. for 10 minutes to obtain a foam sheet (1A) having a thickness of about 0.5 mm.
With respect to the obtained foam sheet (1A), as a water repellent, Fluorosurf (registered trademark) FS-1040TH (manufactured by Fluoro Technology Co., Ltd., HFE, water / oil repellent for HFC solvent) was used. After performing a dipping process for a minute and draining, a drying process was performed at 130 ° C. for 20 minutes to obtain a foam sheet (1B).
The results are shown in Table 1.
Moreover, the photograph figure of the surface / cross-section SEM photograph which image | photographed the produced foam sheet (1A) from diagonally was shown in FIG.

[Example 2]
In Example 1, Fluorosurf (registered trademark) FS-6130 (manufactured by Fluoro Technology Co., Ltd., HFE, aqueous water / oil repellent treatment agent) as a water repellent treatment agent for the obtained foam sheet (1A). Example: Except for performing dipping treatment for 10 minutes with a 5-fold diluted product (using water: ethyl alcohol = 50: 50 solvent), draining, and then drying treatment at 130 ° C. for 20 minutes. 1 was performed to obtain a foam sheet (2B).
The results are shown in Table 1.

[Comparative Example 1]
In Example 1, the foam sheet (C1B) was obtained in the same manner as in Example 1 except that the water-repellent treatment was not performed on the obtained foam sheet (1A).
The results are shown in Table 1.

  The foam sheet of the present invention comprises a water absorbing material, a water retaining material, a cushioning material, a heat insulating material, a sound absorbing material, a separation film, a reflective material, various substrates such as a circuit board, a holding member such as a printing plate, a supporting member, and a polishing process. It is suitable for various uses such as a polishing pad and a surface plate for supporting the polishing pad, a support base used for holding or transporting a semiconductor or various substrates from the back surface by vacuuming or the like.

100 Foam Sheet 10 Foam 10a Foam 10b Foam 20 Base Material 30 Release Film

Claims (8)

A foam sheet comprising a foam having an open cell structure having a through-hole between adjacent spherical cells,
A water repellent layer is provided on at least one surface side,
It is obtained by polymerizing and dehydrating a W / O emulsion containing a continuous oil phase component and an aqueous phase component immiscible with the continuous oil phase component,
The continuous oil phase component includes a hydrophilic polyurethane polymer and an ethylenically unsaturated monomer,
The hydrophilic polyurethane-based polymer includes a polyoxyethylene polyoxypropylene unit derived from polyoxyethylene polyoxypropylene glycol,
5% by weight to 25% by weight in the polyoxyethylene polyoxypropylene unit is polyoxyethylene,
The water absorption is 1.0 times or less,
The shear adhesive strength is 1 N / cm ² or more,
Foam sheet. The foam sheet according to claim 1 , wherein the foam has a surface opening having an average pore diameter of 20 μm or less on the surface of the foam. The foam sheet according to claim 2 , wherein a water repellent layer is provided on at least a part of a hole inner wall of the surface opening. The foam sheet according to any one of claims 1 to 3 , wherein an average pore diameter of the spherical bubbles is less than 20 µm. The foam sheet according to any one of claims 1 to 4 , wherein an average pore diameter of the through-holes is 5 µm or less. Wherein the foam has a density in the ^{0.15g / cm 3 ~0.6g / cm 3} , the foam sheet according to any one of claims 1 to 5. The foam sheet according to any one of claims 1 to 6 , wherein the foam ratio of the foam is 30% or more. The foam sheet according to any one of claims 1 to 7 , wherein a 50% compression load is 300 N / cm ² or less.