JP2010031094A - Foam and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicone-based flexible resin foam having low toxicity and excellent physical properties such as moisture permeability, skin compatibility and low irritation, as well as a high water-absorption rate. <P>SOLUTION: The flexible silicone-based resin foam which has low toxicity and excellent physical properties such as moisture permeability, skin compatibility and low irritation can be obtained by using a resin which has a siloxane unit and an oxyalkylene unit in its molecular structure and does not contain a unit derived from an isocyanate group. Further, the flexible silicone-based resin foam having a high water-absorption rate can be obtained by allowing it to contain an oxyethylene unit as at least one oxyalkylene unit and a polyoxyalkylene-polydimethylsiloxane block copolymer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a foam and a method for producing the same.

  Foam containing air bubbles in the resin is excellent in cushioning, heat insulation, shock absorption, light weight, water absorption, moisture permeability, etc., such as automotive parts such as bumpers and seat cushions, insulation materials, panels, etc. It is used in various fields such as building materials, food applications such as fish boxes and food packaging materials. Also used in medical applications, such as nursing pads, foot care pads, catheter fixing sheets, hemostatic dressings, wound dressings, etc. The resin foam materials used in these medical applications include polyurethane and silicone. Resin, polyolefin, polystyrene and the like are used.

  For example, it is known that a wound dressing material particularly effective for healing deep wounds can be obtained using a hydrophilic polyurethane resin foam (for example, Patent Document 1). However, in polyurethane, there are concerns about the odor of the remaining reaction catalyst and the toxicity of the unreacted isocyanate, and there may be uncomfortable feelings during use due to swelling during water absorption. For this reason, attempts have been made to suppress swelling of the water-absorbent foam (Patent Document 2). However, urethane is preferably used, and the above-mentioned problem of toxicity is not solved.

  On the other hand, what uses the silicone resin foam as a wound dressing is also known (for example, patent document 3). By using a silicone resin that is excellent in moisture permeability, flexibility, etc., a wound dressing material that has no stuffiness, is gentle on the wound surface, and has little worry about toxicity such as isocyanate has been obtained. There is a problem that the affinity with the skin is low, the water absorption, especially the water absorption rate tends to be low, and the wound part with a large amount of exudate has continued discomfort and is difficult to use.

  Conventionally, silicone foam has many excellent physical properties such as heat resistance, hydrophobicity, cold resistance, weather resistance, electrical insulation, flexibility, etc., compared to foams made of other types of polymers such as urethane foam. It is known that it has (for example, patent document 4). However, silicone foam is generally difficult to impart water absorption due to the low surface tension of silicone, and other than medical applications, cosmetic puffs, toiletries, agriculture, horticultural flooring, and cleaning It was difficult to use in fields that require water absorption, such as materials.

On the other hand, as means for improving the paintability and adhesiveness of the silicone foam, it has a carbon-carbon double bond and the molecular skeleton is a polyether-based organic polymer skeleton, a phenol-formaldehyde-based organic polymer skeleton, and An organic compound that is one or more selected from the group consisting of monomeric skeletons of bisphenol A and does not contain a siloxane unit in the molecular skeleton, and a silicone-based resin composition composed of a chain-like polyorganohydrogensiloxane were used. A foam is known (for example, Patent Document 5). However, there is no knowledge regarding the improvement of water absorption and consequently water absorption speed.
Japanese Patent No. 3541948 Special table 2005-516735 7-51139 JP-A-9-124816 Japanese Patent No. 35699919

  Under such circumstances, the problem to be solved by the present invention is a silicone having a high water absorption rate while having excellent physical properties such as low toxicity, moisture permeability, familiarity with skin, and low irritation. System soft resin foam.

  As a result of diligent research for solving the above problems, the present inventors have used a resin having a siloxane unit and an oxyalkylene unit in the molecular skeleton and not containing a unit derived from an isocyanate group. Low toxicity and excellent physical properties such as moisture permeability, familiarity to skin, low irritation, etc., and at least one oxyalkylene unit contains an oxyethylene unit, and polyoxyalkylene-poly It has been found that a silicone-based soft resin foam having a high water absorption rate can be obtained by containing a dimethylsiloxane block copolymer, leading to the present invention.

  That is, the present invention is a foam characterized by using a resin having a siloxane unit and an oxyalkylene unit in the molecular skeleton and not containing a unit derived from an isocyanate group, The present invention relates to a resin foam having an absorption rate of 1 minute or less when 0.1 ml of saline is dropped.

  The present invention also relates to a resin foam, wherein the resin contains an oxyethylene unit as at least one oxyalkylene unit and a polyoxyalkylene-polydimethylsiloxane block copolymer. .

  The present invention also relates to a resin foam characterized in that the resin contains 5 wt% or more and less than 80 wt% of oxyethylene units.

Moreover, this invention relates to the resin foam whose water absorption rate represented by following formula (1) when immersed in physiological saline at 37 degreeC for 24 hours is 200 wt% or more and less than 2000 wt%.
Water absorption = 100 × (foam weight after immersion−foam weight before immersion) ÷ (foam weight before immersion) (1)
In the present invention, the resin may be
(A) a compound having an alkenyl group,
(B) a compound having a hydrosilyl group,
The present invention relates to a resin foam obtained by curing a mixture containing (C) a hydrosilylation catalyst and (D) a polyoxyalkylene-polydimethylsiloxane block copolymer.

  The present invention also relates to (A) a resin foam characterized in that the compound having an alkenyl group is an organic compound containing no siloxane unit in the molecular skeleton.

  The present invention also relates to (A) a resin foam characterized in that the compound having an alkenyl group contains 50 wt% or more of a polyoxyalkylene polymer having at least one alkenyl group at the terminal.

  The present invention also relates to a resin foam characterized in that the resin further contains (E) a foaming agent, and the mixture is foamed simultaneously with curing.

  The present invention also relates to a resin foam characterized in that at least one of the foaming agents (E) is an active hydrogen group-containing compound.

  The present invention also relates to a resin foam, wherein the active hydrogen group-containing compound is a compound having an OH group.

  The present invention also relates to a resin foam, wherein the compound having an OH group is at least one selected from the group consisting of water, alcohol and polyether polyol.

  The present invention also relates to a resin foam, wherein at least one of the compounds having an OH group is polyethylene glycol.

  The present invention also relates to a resin foam, wherein the hydrosilyl group in the compound (B) is present in an amount of 2 molar equivalents or more with respect to the alkenyl group in the compound (A).

The present invention also relates to a resin foam having a density of 10 kg / m ³ or more and less than 500 kg / m ³ , a thickness of 1 mm or more and less than 100 mm, and an open cell ratio of 80% or more.

  The present invention also relates to a resin foam comprising a superabsorbent resin and at least one selected from the group consisting of particles and fibers using the same.

Moreover, this invention relates to the resin foam characterized by the water absorption expansion coefficient represented by following formula (2) at the time of being immersed in physiological saline at 37 degreeC for 24 hours.
Water absorption expansion coefficient = 100 × (foam volume after immersion−foam volume before immersion) ÷ (foam volume before immersion) (2)
Moreover, this invention relates to the wound dressing characterized by using the said resin foam for at least one part.

  Moreover, this invention relates to the adhesive bandage characterized by using the said resin foam for at least one part.

  In addition, the present invention mixes (A) a compound having an alkenyl group, (C) a hydrosilylation catalyst, (E) a foaming agent, and, in some cases, other additives, after mixing the resin composition (B The present invention relates to a method for producing a resin foam, wherein a compound having a hydrosilyl group is added and mixed, followed by injection foaming or spray foaming.

  According to the present invention, a silicone-based soft resin foam having a high water absorption rate is provided. Specifically, water absorption such as wound dressing materials, foot care pads, catheter fixation sheets, hemostatic dressing, nursing pads, and cosmetic puffs, toiletry materials, agricultural, horticultural flooring materials, cleaning materials, etc. It is useful for applications that require high performance.

The resin used for the resin foam of the present invention is characterized by having a siloxane unit and an oxyalkylene unit in the molecular skeleton and containing no unit derived from an isocyanate group. By having a siloxane unit and an oxyalkylene unit in the molecular skeleton, it has excellent balance of moisture permeability and flexibility, affinity with the skin, etc., and does not contain a unit derived from an isocyanate group. In particular, it is possible to obtain a foam that can be suitably used for medical applications. Although it does not specifically limit as an oxyalkylene unit, For example, the compound which has C1-C20 alkylene groups, such as oxymethylene, oxyethylene, oxypropylene, oxyisopropylene, oxybutylene, oxyisobutylene, is mentioned. However, it is preferable that at least one contains an oxyethylene unit from the viewpoint of water absorption, particularly high water absorption rate, and as a medical foam, since it can provide absorbability of body fluids and sweat. More preferably, it consists of oxyethylene units.
The resin foam of the present invention is characterized in that the absorption rate when 0.1 ml of physiological saline is dropped on the surface of the foam is within 1 minute. The water absorption speed is preferably within 30 seconds, and more preferably within 20 seconds.

  In order to express the water absorption rate, it is preferable that the foam resin contains an oxyethylene unit as at least one oxyalkylene unit and a polyoxyalkylene-polydimethylsiloxane block copolymer. In particular, the addition of a polyoxyalkylene-polydimethylsiloxane block copolymer is effective for improving the water absorption rate. The addition amount of the polyoxyalkylene-polydimethylsiloxane block copolymer is not particularly limited, but is preferably 0.01 wt% or more and less than 5 wt%, and preferably 0.02 wt% or more and less than 4 wt%. More preferably, it is 0.03 wt% or more and less than 3 wt%.

  When the water absorption speed of the foam is 1 minute or more, there is a tendency that sufficient water absorption effect cannot be obtained.

Further, the water absorbent resin foam of the present invention has a water absorption rate represented by the following formula (1) when immersed in physiological saline at 37 ° C. for 24 hours: 200 wt% or more and less than 2000 wt%. Preferably, it is more preferably 250 wt% or more and less than 1700 wt%, and further preferably 300 wt% or more and less than 1500 wt%.
Water absorption rate = 100 × (foam weight after immersion−foam weight before immersion) ÷ (foam weight before immersion) (1).

  If the water absorption rate of the foam is less than 200 wt%, there is a tendency that a sufficient water absorption effect cannot be obtained, and if it is 2000 wt% or more, the mechanical properties of the foam tend to be lowered during water absorption, making it difficult to handle.

  In order to express the water absorption rate, the foam resin preferably contains 5 wt% or more and less than 80 wt% of oxyethylene units, more preferably contains 7 wt% or more and less than 70 wt%, more preferably 10 wt% or more and less than 60 wt%. It is more preferable to contain.

The content of oxyethylene units in the foam resin can be calculated from the amount of oxyethylene units in the raw material added at the time of making the resin, but the surfactant analysis method is new (Shoshobo, edited by Surfactant Analysis Study Group, 1987, page 282), and can be measured by a method using the peak intensity derived from the CH ₂ O group in the IR spectrum.

  The resin composition of the present invention is not particularly limited as long as it has the above molecular skeleton. For example, (A) a compound having an alkenyl group, (B) a compound having a hydrosilyl group, (C) A resin obtained by curing a mixture containing a hydrosilylation catalyst and (D) polyoxyalkylene-polydimethylsiloxane block copolymer is preferred because of excellent balance of foam moldability, mechanical properties, water absorption speed, and various physical properties. .

  The compound (A) having an alkenyl group is not particularly limited as long as it is a compound having an alkenyl group. However, an organic compound that does not contain a siloxane unit in the molecular skeleton can be used as an affinity for skin. It is preferable because it is excellent and various properties such as water absorption can be added.

  In the compound (A) having an alkenyl group, when the molecular structure is divided into a skeleton portion and an alkenyl group bonded to the skeleton by a covalent bond, the alkenyl group is present anywhere in the molecule. However, it is preferably present at the side chain or at the end in terms of reactivity.

  The skeleton of the compound (A) having an alkenyl group does not contain silicon as a constituent element for the above reasons, and is at least one selected from the group consisting of only carbon or carbon and oxygen, hydrogen, nitrogen, sulfur, and halogen. It is preferably a normal organic polymer skeleton or organic monomer skeleton containing only Examples of the organic polymer skeleton include polyoxyalkylene-based, polyester-based, polycarbonate-based, saturated hydrocarbon-based, polyacrylate-based, polyamide-based, and phenol-formaldehyde-based (phenol resin-based) skeletons. Examples of the monomer skeleton include phenolic, bisphenolic, and mixtures thereof.

Among these, a soft foam in which a polyoxyalkylene polymer skeleton composed of a repeating unit represented by the general formula (—R ¹ —O—) is useful as a medical foam and has water absorbency. It is preferable to obtain Here, -R < ¹ >-is a divalent alkylene group. The polyoxyalkylene polymer may be composed of one type of repeating unit or may be composed of a plurality of repeating units. The polyoxyalkylene polymer may be a linear polymer or a branched polymer.

Specific examples include polyoxyethylene, polyoxypropylene, polyoxytetramethylene, polyoxyethylene-polyoxypropylene copolymer and the like, and the medical foam has low skin irritation and wets the skin. Particularly preferred skeleton is polyoxypropylene, that is, the above -R ¹ -is -CH ₂ CH (CH ₃ )-. Moreover, it is preferable also from the point of workability | operativity on acquisition. However, if the polyoxyethylene skeleton is not contained in the skeleton of the compound (A) having an alkenyl group in the water-absorbent soft resin foam, it may be possible to separately introduce polyethylene glycol and its derivatives described later. From the viewpoint of

  In particular, the compound (A) having an alkenyl group of the present invention preferably contains 50 wt% or more, more preferably 70 wt% or more of a polyoxyalkylene polymer having at least one alkenyl group at the terminal. And more preferably 80 wt% or more.

  The number average molecular weight of the polyoxyalkylene polymer is preferably 3000 to 50000, more preferably 4000 to 40000, and even more preferably 5000 to 30000 from the viewpoint of good workability at room temperature and good skin affinity. . If the number average molecular weight is less than 3,000, the resulting foam tends to be brittle and difficult to produce. Conversely, if the number average molecular weight exceeds 50,000, the viscosity tends to be high and workability tends to decrease. The number average molecular weight of the polyoxyalkylene polymer is a polystyrene equivalent number average molecular weight measured by GPC.

  The alkenyl group in the compound (A) having an alkenyl group of the present invention is not particularly limited as long as it is a group containing a carbon-carbon double bond that is active for hydrosilylation reaction. The alkenyl group is preferably an aliphatic unsaturated hydrocarbon group having 2 to 20 carbon atoms, more preferably 2 to 6 carbon atoms (eg, vinyl group, allyl group, methylvinyl group, propenyl group, butenyl group, pentenyl group). Group, hexenyl group, etc.), preferably a cyclic unsaturated hydrocarbon group having 3 to 20 carbon atoms, more preferably 3 to 6 carbon atoms (eg, cyclopropenyl group, cyclobutenyl group, cyclopentenyl group, cyclohexenyl group, etc.) ), A methacryl group and the like.

From the viewpoint of easy introduction of the alkenyl group into the skeleton, preferred alkenyl groups include the following (1) and (2). In the following formula, R ² is a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, preferably a hydrogen atom or a methyl group.
(1) H ₂ C═C (R ² ) −
^{(2) HC (R 2)} = CH-.

  The number of average alkenyl groups per molecule in the compound (A) having an alkenyl group of the present invention is preferably at least one, more preferably 1 to 5, more preferably 1 to 3 More preferably, it is particularly preferred to contain 1-2. If the number of average alkenyl groups per molecule in the compound (A) having an alkenyl group is less than 1, the curability tends to be insufficient, and depending on the molecular weight of the skeleton part, When the number of alkenyl groups contained is too large, the network structure becomes dense and the foam becomes hard and brittle, and the flexibility and mechanical strength, as well as the followability to the skin and the tactile sensation tend to be reduced.

The number of average alkenyl groups per molecule is a value measured by iodine value.
The bonding mode of the alkenyl group to the skeleton is not particularly limited, and examples thereof include a direct bond of an alkenyl group, an ether bond, an ester bond, a carbonate bond, and a urea bond.

  The production method of the compound (A) having an alkenyl group of the present invention is not particularly limited. For example, when a polyoxyalkylene polymer is used as a skeleton, a method of introducing an alkenyl group after obtaining a polyoxyalkylene polymer is available. Illustrated. In this case, various known production methods can be applied to the polyoxyalkylene polymer, and a commercially available polyoxyalkylene polymer may be used. A method for introducing an alkenyl group into a polyoxyalkylene polymer is also known. For example, a monomer having an alkenyl group (eg, allyl glycidyl ether) and a monomer for synthesizing a polyoxyalkylene polymer are used. Copolymerization and reactivity with functional groups in polyoxyalkylene polymers in which a functional group (eg, hydroxyl group, alkoxide group) is previously introduced into a desired portion (end of main chain, etc.) And a method of reacting a compound having both a functional group having an alkenyl group and an alkenyl group (eg, acrylic acid, methacrylic acid, vinyl acetate, acrylic acid chloride, etc.).

  The compound (B) having a hydrosilyl group of the present invention is not particularly limited as long as it is a compound having a hydrosilyl group, but has 1 to 100 hydrosilyl groups in one molecule for obtaining a foam. Compounds are preferred. Here, the hydrosilyl group means a group having a Si—H bond.

  In the present invention, when two hydrogen atoms (H) are bonded to the same silicon atom (Si), it is calculated as two hydrosilyl groups.

  In the compound (B) having a hydrosilyl group of the present invention, there is no particular limitation on the chemical structure other than the hydrosilyl group.

  The number average molecular weight of the compound (B) having a hydrosilyl group of the present invention is preferably 400 to 30,000, and more preferably 500 to 10,000. When the number average molecular weight of the compound (B) having a hydrosilyl group is less than 400, foaming during foam molding tends to be severe and foam tends to be difficult to obtain. When the number average molecular weight exceeds 30000, the curing rate is slow, Manufacturing efficiency tends to be low.

  The number of hydrosilyl groups contained in one molecule of the compound (B) having a hydrosilyl group is preferably 1 to 100, and is preferably as long as compatibility with other components is not impaired. If two or more hydrosilyl groups are contained in one molecule of the compound (B), a plurality of compound (A) molecules can be cross-linked during curing, and the number of hydrosilyl groups is less than two. If so, curing is slow and often causes poor curing. As will be described later, when an active hydrogen-containing compound is used as the foaming agent (E), since the compound (B) and the active hydrogen compound undergo dehydrogenative condensation and participate in foaming, the hydrosilyl group In general, the number of is preferably more than 2 although it depends on the target expansion ratio.

  For the same reason, the compound (B) having a hydrosilyl group in the present invention preferably has a hydrosilyl group of 2 molar equivalents or more with respect to the alkenyl group in the compound (A) having an alkenyl group.

  However, when the number of hydrosilyl groups in the compound (B) having a hydrosilyl group is too large, the crosslinking becomes too dense, and the flexibility and skin followability of the obtained foam are liable to decrease. When the stability of B) is deteriorated and a very large amount of hydrosilyl groups remain in the obtained foam, it may cause skin irritation and voids. In addition, the density of the cross-linking affects moisture permeability and water absorption.

  Therefore, the number of hydrosilyl groups in the compound (B) having a hydrosilyl group is the number of alkenyl groups in the compound (A) and the number of functional groups in other additives that react with the hydrosilyl group, including active hydrogen compounds. Select with consideration for balance. Therefore, the compound (B) having a hydrosilyl group in the present invention is 0.1 mol relative to the total of functional groups capable of reacting with the alkenyl group of the compound (A) and the hydrosilyl group present in other additives. It is preferable to have a hydrosilyl group of not less than 50 mole equivalents, more preferably not less than 0.2 mole equivalents and not more than 30 mole equivalents, particularly preferably not less than 0.5 mole equivalents and not more than 20 mole equivalents.

  The compound (B) having a hydrosilyl group in the present invention may be used alone or in combination of two or more.

  The compound (B) having a hydrosilyl group of the present invention preferably has good compatibility with the compound (A) having an alkenyl group. From the viewpoint of easy availability of raw materials and compatibility with the compound (A) having an alkenyl group, organohydrogensiloxane is exemplified as the preferred compound (B) having a hydrosilyl group.

  A typical example of the organohydrogensiloxane is a compound represented by the following general formula (3) or (4).

The value of a in the general formula (3) or (4) corresponds to the number of hydrosilyl groups in the molecule. a is 1 or more, b is 0 or more, and the value of a + b is not particularly limited, but is preferably 1 to 100. R ³ is not particularly limited, but is preferably at least one selected from a hydrocarbon group having 2 to 20 carbon atoms in the main chain and a polyoxyalkylene group.

The compound of the above general formula (3) or (4) can be obtained by introducing unmodified methyl hydrogen silicone itself or R ³ after modifying it. Here, the unmodified methylhydrogen silicone, corresponds to the compound R ³ are all H in the formula (3), "Silicone market outlook published by CMC Co., Ltd. (1990.1.31) - As described in "Manufacturer strategy and application development-", it is used as a raw material for various modified silicones. Examples of the organic compound for introducing R ³ include α-olefin, styrene, α-methylstyrene, allyl alkyl ether, allyl alkyl ester, allyl phenyl ether, allyl phenyl ester, polyoxyalkylene allyl ether, and the like. The number of hydrosilyl groups in the molecule after modification can be adjusted by the amount of the organic compound added for modification.

  The amount ratio of the compound (A) and the compound (B) for forming the foam of the present invention is not particularly limited, but as described above, with respect to the total amount of alkenyl groups derived from the compound (A), Expressed by the total amount of hydrosilyl groups derived from compound (B). As described above, the compound (B) in the present invention preferably has a hydrosilyl group of 2 molar equivalents or more with respect to the alkenyl group of the compound (A). More specifically, the type of foaming agent used, Determined according to foaming method. Further, the amount ratio of the compound (A) to the compound (B) is determined according to the amount of the functional group described above, but considering the foam moldability, the weight of the compound (A) and the compound (B). The ratio (A) / (B) is preferably 0.05 or more and 20 or less, and more preferably 0.1 or more and 10 or less.

The hydrosilylation catalyst (C) in the present invention is not particularly limited, and any catalyst can be used as long as it promotes the hydrosilylation reaction. Specific examples of the hydrosilylation catalyst (C) include chloroplatinic acid, platinum-vinylsiloxane complexes (for example, platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex, platinum-1 , 3,5,7-tetravinyl-1,3,5,7-tetramethyl cyclotetrasiloxane complex), platinum - olefin complexes _{(e.g., Pt p (ViMe 2 SiOSiMe 2} Vi) q Pt [(MeViSiO) 4] _r (wherein, p, q and r are positive integers and Vi is a vinyl group)). Among these, from the viewpoint of catalytic activity, a platinum complex catalyst not containing a conjugate base of a strong acid as a ligand is preferable, a platinum-vinylsiloxane complex is more preferable, and platinum-1,3-divinyl-1,1,1 is preferable. A 3,3, -tetramethyldisiloxane complex or a platinum-1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane complex is particularly preferred.

Although the usage-amount of the hydrosilylation catalyst (C) in this invention does not have a restriction | limiting in particular, Preferably it is 10 ^<-8 > ^-10 < ^-1 > mol with respect to ¹ mol of total amounts of the alkenyl group by a compound (A), More preferably, 10 ^-6 to 10 ^-3 mol. If the usage-amount of a hydrosilylation catalyst (C) is in the said range, it will become easy to achieve appropriate hardening rate, stable sclerosis | hardenability, ensuring of a required pot life, etc.

  The polyoxyalkylene-polydimethylsiloxane block copolymer (D) in the present invention is not particularly limited, and any can be used as long as the water absorption rate can be improved. For example, the specific structure of the polyoxyalkylene-polydimethylsiloxane block copolymer (D) includes an AB type diblock body, an ABA type triblock body, an (AB) n type multiblock body, Examples include a branched type, a pendant type, and a star type. In addition, specific structures of polyoxyalkylene include polyoxyethylene, polyoxypropylene, polyoxytetramethylene, polyoxyethylene-polyoxypropylene copolymer, and the terminal structure is also OH. Examples thereof include a base end, an ether end such as methoxy and t-butoxy, and a reactive allyl end. Among these, from the viewpoint of improving the water absorption rate, suppressing a decrease in water absorption rate over time due to elution, and balancing the foam regulating effect during foam formation and the bubble breaking effect for improving the open cell ratio The terminal methoxy ether type of polyoxyethylene-polyoxypropylene copolymer is preferably used as the polyoxyalkylene skeleton in the ABA type triblock body.

  The method for producing the water-absorbent soft resin foam in the present invention is not particularly limited, and a resin having a siloxane unit and an oxyalkylene unit in the molecular skeleton and containing no unit derived from an isocyanate group is obtained. After that, a foaming agent (E) is added thereto and heated for foaming, or a method of impregnating the foaming agent (E) under pressure and then releasing the pressure for foaming is possible. A method comprising adding a foaming agent (E) to a mixture comprising the compound (A), the compound (B) having a hydrosilyl group and the hydrosilylation catalyst (C), and foaming the mixture simultaneously with curing is a foam molding property or It is preferable from the viewpoint of production efficiency.

  The foaming agent (E) in the present invention is not particularly limited. For example, it is usually used for organic foams such as polyurethane, phenol, polystyrene, polyolefin, etc. Examples thereof include chemical foaming agents that generate gas by reaction, active hydrogen group-containing compounds that react with hydroxyl groups to generate hydrogen, and the like. Among these, the active hydrogen group-containing compound is preferably used because it contributes to the development of characteristics as a medical foam such as improvement in open cell ratio and flexibility.

  The active hydrogen group-containing compound is not particularly limited as long as it is a compound containing an active hydrogen group that reacts with a hydroxyl group to generate hydrogen. From the viewpoint of flexibility and water absorption, silicone foam A compound in which oxygen is directly bonded to carbon or water is preferable instead of the OH group-containing polysiloxane used in the above.

  As the active hydrogen-containing compound in which oxygen is directly bonded to carbon, a saturated hydrocarbon alcohol, carboxylic acid or water is preferably used. Specific examples thereof include water; methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, tert-butanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene Monohydric alcohols such as glycol monobutyl ether, diethylene glycol monomethyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, glyceryl diallyl ether; ethylene glycol, propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, diethylene glycol, triethylene glycol, neopentyl glycol, 1 Polyhydric alcohols such as 6-hexamethylene glycol, 1,9-nonamethylene glycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose, glyceryl monoallyl ether; polypropylene glycol, polyethylene glycol, copolymers thereof, poly Polyether polyols such as tetramethylene glycol (including those containing 3 or more OH groups in one molecule starting from sorbitol, sucrose, tetraethylenediamine, ethylenediamine, etc.); adipate polyol, polycaprolactone polyol, polycarbonate Polyester polyols such as polyols; epoxy-modified polyols; polyether ester polyols; benzylic ether type phenol polyols, etc. Phenolic polyols; Fluoropolyols such as Lumiflon (Asahi Glass Co., Ltd.); Polybutadiene polyols; Hydrogenated polybutadiene polyols; Castor oil-based polyols; Halogen-containing flame-retardant polyols; Phosphorus-containing flame-retardant polyols; Monovalent such as acetic acid and propionic acid Carboxylic acids such as saturated carboxylic acids; compounds having phenolic OH groups such as phenol, cresol, xylenol, resorcin, catechol, pyrogallol, bisphenol A, bisphenol B, bisphenol S, phenol resin; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl vinyl ether, N-methylol (meth) acrylamide, Aronics 5700 manufactured by Toa Synthetic Chemical Industry Co., Ltd., 4-hydro Xylstyrene, HE-10, HE-20, HP-10 and HP-20 [all acrylate ester oligomers having an OH group at the terminal] manufactured by Nippon Shokubai Chemical Industry Co., Ltd., Bremer PP manufactured by Nippon Oil & Fats Co., Ltd. Series [polypropylene glycol methacrylate], Blemmer PE series [polyethylene glycol monomethacrylate], Blemmer PEP series [polyethylene glycol polypropylene glycol methacrylate], Blemmer AP-400 [polypropylene glycol monoacrylate], Blemmer AE-350 [polyethylene glycol monoacrylate], BLEMMER NKH-5050 [polypropylene glycol polytrimethylene monoacrylate] and BLEMMER GLM [glycerol monomethacrylate OH group-containing vinyl monomers such as ε-caprolactone-modified hydroxyalkyl vinyl monomers obtained by reaction of OH group-containing vinyl compounds with ε-caprolactone [wherein OH group-containing vinyl monomers are compound (A) And an acrylic resin having an OH group that can be obtained by copolymerization of the OH group-containing vinyl monomer with acrylic acid, methacrylic acid, or a derivative thereof; Other examples include resins having an OH group, such as alkyd resins and epoxy resins.

  Among these active hydrogen group-containing compounds, at least one selected from the group consisting of water, primary alcohols, and polyether polyols is preferable from the viewpoints of reactivity and handleability. Water, ethanol, and polyethylene glycol are more preferable from the viewpoint that there is little influence on the human body when used as a use. When polyethylene glycol is used, it is particularly preferably used because water absorption can be imparted to the foam.

  The hydroxyl group equivalent in the active hydrogen group-containing compound in the present invention is preferably 0.1 mmol / g or more because the volume of the active hydrogen group-containing compound to be added increases and the expansion ratio does not increase when the hydroxyl group equivalent decreases. Furthermore, 0.5 mmol / g or more is more preferable from the point of reactivity.

  In the present invention, carboxylic acids such as acetic acid and propionic acid can also be used in order to easily perform a dehydrogenation reaction with the hydrosilyl group in the compound (B) having a hydrosilyl group. Also, two or more kinds of active hydrogen group-containing compounds can be used in combination for adjusting the foaming rate.

  In addition, ethylene glycol monoallyl ether, polyethylene glycol monoallyl ether, polypropylene glycol monoallyl ether, monoallyl ether of ethylene glycol propylene glycol copolymer is used to adjust the physical properties such as crosslinking degree, foam moldability, and water absorption. , Glycerin monoallyl ether, glyceryl diallyl ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, and other compounds that have both a hydrosilylatable carbon-carbon double bond and an OH group in the molecule You can also

  In addition, when an active hydrogen compound having two or more OH groups in one molecule, or an active hydrogen compound having both OH groups and alkenyl groups in one molecule, (B) in the compound having a hydrosilyl group A large amount of the active hydrogen compound is used to generate hydrogen gas by the reaction of the hydrosilyl group and the OH group in the active hydrogen compound and to form a reaction cross-linking structure of the hydrosilyl group, OH group and alkenyl group. Is undesirable because it may cure before sufficient foaming.

  In the present invention, when an active hydrogen compound is used as the foaming agent (E), the compounding ratio of the compound (A), the compound (B) and the foaming agent (E) is the structure of each compound, the target expansion ratio, and the target. Although it is appropriately selected depending on the physical properties and is not particularly limited, the number of moles x of the hydrosilyl group in the compound (B), the number of moles y of the alkenyl group in the compound (A), and the foaming agent (E) The ratio of the OH group to the sum of the number of moles z is preferably x: y + z = 50: 1 to 1:10, more preferably x: y + z = 30: 1 to 1: 5, and x: It is more preferable that y + z = 20: 1 to 1: 2. When the molar ratio of hydroxyl groups exceeds x: y + z = 50: 1, the crosslinking density tends to be low and sufficient mechanical strength tends not to be obtained, and the molar ratio is less than x: y + z = 1: 10. Sufficient foaming and curing may not occur.

  The ratio of the number of moles y of the alkenyl group of the compound (A) to the number of moles z of the OH group of the foaming agent (E) is not particularly limited, and the desired foaming magnification, the desired physical properties, the compound (A ) And the type of foaming agent (E) can be selected as appropriate. In general, y: z = 100: 1 to 1: 100 is preferable, and y: z = 10: 1 to 1: 1. 20 is more preferable.

  As the foaming agent (E), in addition to the active hydrogen compound, the above-mentioned physical foaming agent and other chemical foaming agents may be used alone or in combination with the active hydrogen compound.

  The physical foaming agent is not particularly limited as long as it does not inhibit the hydrosilylation reaction, but is preferably a compound having a boiling point of 100 ° C. or less, from the viewpoint of foamability, workability and safety, and 50 ° C. or less. Is more preferable. Specific examples include organic compounds such as hydrocarbons, chlorofluorocarbons, alkyl chlorides and ethers, and inorganic compounds such as carbon dioxide, nitrogen and air. From the viewpoint of environmental compatibility, hydrocarbons, ethers, carbon dioxide and nitrogen. It is preferable to use a compound selected from air. Of these, hydrocarbons include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2 , 3-dimethylbutanecrobutane, cyclopentane, cyclohexane and the like. Examples of ethers include dimethyl ether, diethyl ether, ethyl methyl ether, dipropyl ether, diisopropyl ether, butyl methyl ether, butyl ethyl ether, tert-butyl methyl ether, tert-butyl ethyl ether, 1,1-dimethylpropyl methyl. Examples include ether. In addition, when performing mechanical stirring in the air at the time of foam manufacture, air bubbles may be formed by the air entrained with the stirring, which is also considered to be one of physical foaming agents. However, when these physical foaming agents are used, it may be necessary to consider the effect of the residue on the human body when used as a medical application. It is preferable to remove by heating and curing at a temperature.

The chemical foaming agent other than the active hydrogen compound is not particularly limited as long as it does not inhibit the hydrosilylation reaction. For example, NaHCO ₃ , (NH ₄ ) ₂ CO ₃ , NH ₄ HCO ₃ , NH ₂ NO ₂ , Organic chemical foaming agents such as inorganic chemical foaming agents such as Ca (N ₃ ) ₂ and NaBH ₄ , azodicarbonamide, azobisisobutyronitrile, barium azodicarboxylate, dinitrosopentamethylenetetramine, paratoluenesulfonyl hydrazide Agents and the like. However, when these chemical foaming agents are used, the use of the chemical foaming agent is limited because it may be necessary to consider the influence of the residue on the human body when used as a medical application.

  If necessary, the foam of the present invention may further include a filler, an antioxidant, a radical inhibitor, an ultraviolet absorber, an adhesion improver, a flame retardant, a polydimethylsiloxane-polyalkylene oxide surfactant, or Foam stabilizers such as organic surfactants (polyethylene glycol alkylphenyl ether, etc.), acids or basic compounds (additives for adjusting the reaction between hydrosilyl groups and OH groups, which suppress the condensation reaction with acids, ), Storage stability improver, ozone degradation inhibitor, light stabilizer, thickener, plasticizer, coupling agent, antioxidant, thermal stabilizer, conductivity enhancer, antistatic agent, radiation shielding An agent, a nucleating agent, a phosphorus peroxide decomposing agent, a lubricant, a pigment, a metal deactivator, a physical property adjusting agent, and the like can be added as long as the object and effect of the present invention are not impaired. However, since it is used for medical purposes, its use may be limited.

  In the present invention, among these, for the purpose of improving the water absorption and water absorption rate described later, it is possible to add at least one selected from the group consisting of a superabsorbent resin, particles using the same, and fibers. it can.

  Specific examples of the superabsorbent resin include natural polysaccharides, carboxymethyl cellulose (CMC), alginic acid, alginate, polyacrylic acid, polyacrylamide, polyacrylate, polymethacrylate, polyacrylonitrile, polovinylpyrrolidone, polyvinyllactam, polyvinylpyrimidine. Zin, polyvinyl alcohol, polyvinyl acetate, polyethylene oxide, gelatin or other hydrophilic polypeptide, carrageenan, pectin, xanthan, chitin, chitosan, starch and salts thereof, derivatives, starch-acrylic acid graft copolymer, vinyl alcohol- Examples include acrylate copolymers, ethylene-vinyl alcohol copolymers, polyacrylonitrile-methyl methacrylate-butadiene copolymers, and mixtures thereof.

  The method of integrating the superabsorbent resin and the particles, fibers and foam using the superabsorbent resin is not particularly limited, but the superabsorbent resin and the foam using the superabsorbent resin and the particles and fibers using the superabsorbent resin are not particularly limited. And a method of obtaining a foam after mixing a superabsorbent resin and particles and fibers using the same into a foamable resin composition.

  Further, as an additive that contributes to the improvement of water absorption, water absorption such as fine powder with a particle size of 1000 nm or less having a hydroxyl group on the surface, such as anhydrous silica having a silanol group on the surface (silicon oxide), smectite, swellable fluoromica, etc. Layered silicates or organically treated products thereof, zeolites, activated carbon, alumina, silica gel, porous glass, porous materials such as activated clay and diatomaceous earth may be added.

  In addition, a surfactant can be added for the purpose of improving foam stability and compatibility of the compounds (A) to (E). The type of surfactant is not particularly limited, but specific examples include alkyl sulfates such as sodium lauryl sulfate, polyoxyethylene alkyl ether sulfates such as polyoxyethylene lauryl sodium sulfate, poly Oxyethylene alkyl ether acetate, lauryltrimethylammonium chloride, alkoxypropyltrimethylammonium chloride, dialkyldimethylammonium chloride, benzalkonium chloride solution, alkyldimethylaminoacetic acid betaine, alkyldimethylamine oxide, alkylcarboxymethylhydroxyethylimidazolinium betaine, Nonionic biosurfactant such as alkylamidopropyl betaine, glycerin fatty acid ester, propylene glycol fatty acid ester, sorbitan fatty acid ester And the like.

The density of the foam of the present invention is not particularly limited, is preferably less than 10 kg / m ³ or more 500 kg / m ^3, more preferably less than 20 kg / m ³ or more 400 kg / m ^3. When the density is less than 10 kg / m ³ , the mechanical properties are deteriorated and the handleability is poor, and when the density is 500 kg / m ³ or more, the foam properties such as flexibility tend not to be obtained.

  The open cell ratio of the foam of the present invention is not particularly limited, but is preferably 80% or more, and more preferably 90% or more. When the open cell ratio is less than 80%, there is a tendency that it is difficult to obtain suitable characteristics as a medical foam, such as flexibility and touch, and it is also difficult to obtain water absorption described later. Note that the open cell ratio is measured according to ASTM D2856 (1998).

  The thickness of the foam of the present invention is preferably 1 mm or more and less than 100 mm. When the thickness is less than 1 mm, a sufficient function as a foam cannot be exhibited, and when the thickness is 100 mm or more, handling when used in medical applications becomes difficult.

Also in the medical foam of the present invention, the water absorption represented by the following formula (1) when immersed in physiological saline at 37 ° C. for 24 hours may be 200 wt% or more and less than 2000 wt%. Preferably, it is more preferably 250 wt% or more and less than 1700 wt%, and further preferably 300 wt% or more and less than 1500 wt%.
Water absorption rate = 100 × (foam weight after immersion−foam weight before immersion) ÷ (foam weight before immersion) (1).

Furthermore, when the foam of the present invention has a water absorption expansion coefficient represented by the following formula (2) of less than 50 vol% when immersed in physiological saline at 37 ° C. for 24 hours, The body fluid absorbability is good, and it is particularly preferable because it can be suitably used for a wound dressing or the like.
Water absorption expansion coefficient = 100 × (foam volume after immersion−foam volume before immersion) ÷ (foam volume before immersion) (2).

  If the water absorption is less than 200 wt%, sufficient sweat absorption / absorbing liquid effect cannot be obtained, and if it is 2000 wt% or more, the mechanical properties of the foam deteriorate during water absorption and are difficult to handle. The water absorption is more preferably 250 wt% or more and less than 1700 wt%, and particularly preferably 300 wt% or more and less than 1500 wt%.

  With respect to the water absorption expansion coefficient, 50 vol% or more is not preferable because a feeling of pressure or discomfort due to expansion occurs. The water absorption swelling rate is more preferably less than 40 vol%, and particularly preferably less than 30 vol%.

  Moreover, in order to express the water absorption characteristics, the foam resin preferably contains 5 wt% or more and less than 80 wt% of oxyethylene units, more preferably contains 7 wt% or more and less than 70 wt%, more preferably 10 wt% or more and less than 60 wt%. It is more preferable to contain.

  The form of the foam of the present invention is not particularly limited, and examples thereof include a plate shape, a sheet shape, an indeterminate lump shape, a bead shape, or a bag shape or a shape formed in clothes. The shape is used for general purposes. In addition, the foam may be used alone, or may be integrally formed with a material such as a film, cloth, nonwoven fabric, or paper. Further, as in the case of the above-mentioned wound dressing, it can be used by being integrated with an adhesive, an adhesive film, a bandage or the like when directly attached to the skin.

  Further, the foam of the present invention may be used while leaving the skin layer formed at the time of foam molding, or may be cut out or cut into a desired form. However, for applications that require the above-mentioned water absorption properties to be effectively expressed, such as wound dressings, it is necessary to excise the epidermis layer or to provide an opening in the epidermis layer.

  The method for producing the foam of the present invention is not particularly limited. As described above, the compound (A) having an alkenyl group, the hydrosilylation catalyst (C), the foaming agent (E), and optionally other additions. After mixing the resin composition to which the product is added, the method of adding the compound (B) having a hydrosilyl group, mixing, injection foaming or spray foaming, and molding into a desired form is preferably used.

Next, although the foam of this invention is demonstrated still in detail based on an Example, this invention is not restrict | limited only to this Example. Unless otherwise specified, the parts in Examples and Comparative Examples represent parts by weight, and% represents% by weight. In the examples, the following compounds were used.
A: Compound having an alkenyl group A-1: Allyl group-terminated polyoxyalkylene (see synthesis example below, containing alkenyl group 0.219 mmol / g)
B: Compound having hydrosilyl group B-1: KF-99 (Methyl hydrogen silicone oil manufactured by Shin-Etsu Chemical Co., Ltd., containing 16.6 mmol / g of hydrosilyl group)
C: Hydrosilylation catalyst C-1: Platinum-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex (3 wt% platinum isopropanol solution)
D: Polyoxyalkylene-polydimethylsiloxane block copolymer D-1: Methoxy-terminated polyoxyethylenepropylene copolymer-polydimethylsiloxane block copolymer (manufactured by Dow Corning Toray, SF2904)
E: Foaming agent E-1: Ethanol (containing 21.7 mmol / g of OH groups)
E-2: Polyethylene glycol (manufactured by Sanyo Chemical Industries, Ltd., Macrogol 400, molecular weight 400, containing 5.00 mmol / g OH group)
E-3: A synthesis example of isopentane compound A-1 is shown below.

(Synthesis of Compound A-1)
An oxypropylene polymer glycol having a number average molecular weight of 3000 was obtained by a polymerization method using caustic alkali. According to the method of Synthesis Example 1 of JP-A-5-117521, propylene oxide is polymerized using a double metal cyanide complex catalyst (zinc hexacyanocobaltate) using the oxypropylene polymer glycol as an initiator, and the number average molecular weight 13800 polymers were obtained. The polymer is converted to an allyl group using a 28% methanol solution of sodium methylate and allyl chloride, and then desalted and purified to have approximately two allyl group ends in one molecule. A polyoxyalkylene compound (Compound A-1) was obtained. The amount of allyl terminal groups of the obtained polymer was 0.219 mmol / g.

Example 1
0.9 part by weight of polyoxyalkylene-polydimethylsiloxane block copolymer (D-1), 7 parts by weight of ethanol (E-1) as a blowing agent and polyethylene glycol with respect to 100 parts by weight of compound (A-1) (E-2) 22 parts by weight and hydrosilylation catalyst (C-1) 0.3 part by weight were added and mixed well, and further 13 parts by weight of compound (B-1) was added and mixed rapidly. It was allowed to stand overnight at room temperature to obtain a foam. The density of the obtained foam was 130 kg / m ³ , and the open cell ratio was 100%. The measurement results for the obtained foam are shown in Table 1.

(Example 2)
0.9 part by weight of polyoxyalkylene-polydimethylsiloxane block copolymer (D-1), 7 parts by weight of ethanol (E-1) as a blowing agent and polyethylene glycol with respect to 100 parts by weight of compound (A-1) (E-2) 22 parts by weight, isopentane (E-3) 5 parts by weight, hydrosilylation catalyst (C-1) 0.3 part by weight were added and mixed well, and further compound (B-1) 13 Part by weight was added and mixed quickly. It was allowed to stand overnight at room temperature to obtain a foam. The density of the obtained foam was 110 kg / m ³ and the open cell ratio was 100%. The measurement results for the obtained foam are shown in Table 1.

(Comparative Example 1)
To 100 parts by weight of the compound (A-1), 12 parts by weight of ethanol (E-1) and 0.3 part by weight of the hydrosilylation catalyst (C-1) are added and mixed well as a foaming agent. 13 parts by weight of (B-1) was added and quickly mixed. It was allowed to stand overnight at room temperature to obtain a foam. The density was 100 kg / m ³ and the open cell rate was 96%. The measurement results for the obtained foam are shown in Table 1.

(Comparative Example 2)
7 parts by weight of ethanol (E-1) and 22 parts by weight of polyethylene glycol (E-2) and 0.3 parts by weight of hydrosilylation catalyst (C-1) as a blowing agent with respect to 100 parts by weight of compound (A-1) Was added and mixed well. Furthermore, 13 parts by weight of the compound (B-1) was added and quickly mixed. It was allowed to stand overnight at room temperature to obtain a foam. The density of the obtained foam was 120 kg / m ³ and the open cell ratio was 100%. The measurement results for the obtained foam are shown in Table 1.

From the above results, it is clear that the present invention provides a soft resin foam having a high water absorption rate, which has a siloxane unit and an oxyalkylene unit in the molecular skeleton and does not contain a unit derived from an isocyanate group. is there.
In addition, the measurement and evaluation in an Example and a comparative example were performed by the following conditions and methods.

(1) Oxyethylene unit content in foam resin The weight ratio of polyethylene glycol added to the weight of the foam or the weight ratio excluding the allyl group in polyethylene glycol monoallyl ether was calculated and used as the content.

(2) Density The density of the obtained foam was measured according to JISK6400. However, the sample was cut out in a cubic size with a side of about 20 mm, and the skin portion was removed before use.

(3) Open cell ratio The open cell ratio of the obtained foam was measured according to ASTM D2856 (1998). However, the sample was cut out in a cubic size with a side of about 20 mm, and the skin portion was removed before use.

(4) Water absorption characteristics When 0.1 ml of physiological saline is dropped on the foam from which the skin portion has been removed, the time until it is visually recognized that the droplet has been completely absorbed by the foam is measured, and the absorption rate It was.

Moreover, the water absorption rate represented by following formula (1) was calculated | required by immersing the obtained foam in physiological saline at 37 degreeC for 24 hours, and measuring the weight before and behind immersion.
Water absorption = 100 × (foam weight after immersion−foam weight before immersion) ÷ (foam weight before immersion) Formula (1)
However, the sample was cut out in a cubic size with a side of about 20 mm, and the skin portion was removed before use.

Similarly, the volume before and after immersion for 24 hours was calculated from the outer shape using a caliper or a thickness gauge, and the water absorption expansion coefficient represented by the following formula (2) was obtained.
Water absorption expansion coefficient = 100 × (foam volume after immersion−foam volume before immersion) ÷ (foam volume before immersion) (2).

(5) Hardness A rheometer (RT-200J-CW, manufactured by FUDOH) is used for the obtained foam, and a cylinder with a diameter of 15 mm is pushed to 25% of the sample thickness at a speed of 50 mm / min. The test piece was stopped in a state where the compression stress was measured after holding for 30 seconds. However, the sample was cut out in a cubic size with a side of about 25 mm, and the skin portion was removed for use.

Claims (19)

  A foam characterized by using a resin having a siloxane unit and an oxyalkylene unit in the molecular skeleton, and containing no unit derived from an isocyanate group, wherein physiological saline is added to the surface of the foam. A resin foam having an absorption rate of 1 minute or less when 1 ml is dropped.   2. The resin foam according to claim 1, wherein the resin contains an oxyethylene unit as at least one oxyalkylene unit and a polyoxyalkylene-polydimethylsiloxane block copolymer. body.   The resin foam according to claim 1 or 2, wherein the resin contains 5 wt% or more and less than 80 wt% of oxyethylene units. The resin foam according to any one of claims 1 to 3, wherein the water absorption represented by the following formula (1) when immersed in physiological saline at 37 ° C for 24 hours is 200 wt% or more and less than 2000 wt%.
Water absorption = 100 × (foam weight after immersion−foam weight before immersion) ÷ (foam weight before immersion) (1) The resin is
(A) a compound having an alkenyl group,
(B) a compound having a hydrosilyl group,
The resin foam according to claim 1, which is obtained by curing a mixture containing (C) a hydrosilylation catalyst and (D) a polyoxyalkylene-polydimethylsiloxane block copolymer.   (A) The resin foam according to claim 5, wherein the compound having an alkenyl group is an organic compound containing no siloxane unit in the molecular skeleton.   The resin foam according to claim 5 or 6, wherein the compound (A) having an alkenyl group contains 50 wt% or more of a polyoxyalkylene polymer having at least one alkenyl group at the terminal.   The resin foam according to any one of claims 5 to 7, wherein (E) a foaming agent is further contained in the resin, and the mixture is foamed simultaneously with curing.   The resin foam according to claim 8, wherein at least one of the foaming agents (E) is an active hydrogen group-containing compound.   The resin foam according to claim 9, wherein the active hydrogen group-containing compound is a compound having an OH group.   The resin foam according to claim 10, wherein the compound having an OH group is at least one selected from the group consisting of water, alcohol, and polyether polyol.   The resin foam according to claim 10, wherein at least one of the OH group-containing compounds is polyethylene glycol.   The resin foam according to claim 5, wherein the hydrosilyl group in the compound (B) is present in an amount of 2 molar equivalents or more based on the alkenyl group in the compound (A). The resin according to any one of claims 1 to 13, wherein the density is 10 kg / m ³ or more and less than 500 kg / m ³ , the thickness is 1 mm or more and less than 100 mm, and the open cell ratio is 80% or more. Foam.   The resin foam according to any one of claims 1 to 14, wherein at least one selected from the group consisting of a superabsorbent resin, particles using the same, and fibers is integrated. The water absorption expansion coefficient represented by the following formula (2) when immersed in physiological saline at 37 ° C for 24 hours is less than 50 vol%, according to any one of claims 1 to 15, Resin foam.
Water absorption expansion coefficient = 100 × (foam volume after immersion−foam volume before immersion) ÷ (foam volume before immersion) (2)   A wound dressing characterized in that the resin foam according to any one of claims 1 to 16 is used at least in part.     An adhesive bandage characterized in that the resin foam according to any one of claims 1 to 16 is used at least in part.   After mixing (A) a compound having an alkenyl group, (C) a hydrosilylation catalyst, (E) a blowing agent, and optionally other additives, (B) having a hydrosilyl group The method for producing a resin foam according to any one of claims 1 to 18, wherein the compound is added and mixed, and injection foaming or spray foaming is performed.