WO2012023471A1 - Pressure dispersion material and process for producing same - Google Patents

Abstract

Provided is a pressure dispersion material that comprises a composite polymeric hydrogel to which suitable load dispersion properties, moisture permeability, and water-absorbing properties have been imparted. The pressure dispersion material comprises a porous gel which comprises: a three-dimensional network formed from (A) a polymer of a water-soluble organic monomer and (B) a clay mineral; and (C) a lowly volatile medium incorporated into the network. The lowly volatile medium (C) is a lowly volatile medium which has a volatility of 0.1 g/cm²·hr·60ºC·atm or less or a lowly volatile medium which has a vapor pressure measured at 20ºC of 1,000 Pa or lower and a boiling point measured at 1 atm of 130ºC or higher.

Description

Pressure dispersion material and manufacturing method thereof

The present invention relates to a pressure dispersion material and a manufacturing method thereof. More specifically, the present invention relates to a pressure dispersion material used for pressure-absorbing pads and the like for pressure ulcer prevention tools and various appliances in medical and daily life fields such as orthopedics, surgery, rehabilitation, nursing, nursing care, and sports.

Conventionally, pressure bedding has been used in bedding, chairs (including wheelchairs), vehicle seats, cushions, etc., to disperse body pressure, enhance comfort and prevent pressure ulcers. In addition, pressure dispersion materials are used for muscle and joint supporters, lower wrapping materials for prosthetic limbs and external fixation materials (coil bandages, under sleeves, etc.), insoles for shoes and footwear, and for patients with foot disease such as diabetes. As a pressure-removing pad, it is also applied to buffer friction, impact, pressure and the like.

These pressure dispersion materials have been tried to improve and improve body pressure dispersibility and comfort because they are used for a long time. For example, Patent Document 1 states that “a body pressure dispersion material characterized in that a substance having a small pressure deformation is mixed in a gel substance, and the substance is dissolved or contracted later to form a cavity therein. Is disclosed (see claim 1 of the document). This body pressure dispersion material has good body pressure dispersibility, and is lightweight and easy to handle.

Further, Patent Document 2 discloses a cushion material comprising active hydrogen component polyether polyol, organic polyisocyanate, and foaming agent as essential components, and having a predetermined density and displacement force (the document). (See claim 2). This cushion material is excellent in body pressure dispersibility and has good characteristics against shearing force.

In relation to the present invention, in recent years, organic / inorganic composite polymer hydrogels (hereinafter simply referred to as “poly (N-isopropylacrylamide)” and “poly (N, N-dimethylacrylamide)”), which are composed of an organic polymer and an inorganic swellable clay. "Organic / inorganic composite polymer gel" has been developed (see Patent Document 3).

Organic / inorganic composite polymer gels are attracting attention as hydrogel materials having unprecedented high mechanical properties. Patent Document 4 discloses a foam of an organic / inorganic composite polymer gel that has both light weight and high stretchability and flexibility. Patent Document 5 describes a gel containing a low-volatile medium as an organic / inorganic composite polymer gel capable of maintaining stable performance even in an open air system.

JP 2002-60533 A JP 2006-051067 A JP 2002-53629 A Japanese Patent No. 4245406 JP 2006-28446 A

Patent Documents 4 and 5 describe that organic / inorganic composite polymer gels or foams thereof can be used in fields such as medical and hygiene products and household products. However, there is no disclosure about using these organic / inorganic composite polymer gels as the pressure dispersion material. In particular, there is no disclosure about a technique in which a human body such as a pressure dispersion material is brought into contact with the human body for a long time and used for a long time.

Accordingly, the main object of the present invention is to provide a pressure dispersion material comprising an organic / inorganic composite polymer gel imparted with suitable load dispersibility.
Another object of the present invention is to provide a pressure dispersion material comprising an organic / inorganic composite polymer gel with little discomfort even when it is in contact with a human body for a long time and used for a long time.

In order to solve the above-mentioned problems, the present inventors have intensively studied paying attention to the situation in which the material and the living body are in contact with each other for a long time, and as a result, the organic / inorganic composite polymer gel having new characteristics has It came to complete the porous gel used for a dispersing material.

That is, the present invention includes a porous gel containing a low-volatile medium (C) in a three-dimensional network formed from a polymer (A) of a water-soluble organic monomer and a clay mineral (B). A pressure dispersion material is provided. The low volatile medium (C) is a low volatile medium of 0.1 g / cm ² · hr · 60 ° C · 1 atm or less, or a low volatility of which vapor pressure at 20 ° C is 1000 Pa or less and boiling point at 1 atm is 130 ° C or more. It is a sex medium.
In this pressure dispersion material, it is preferable that the porous gel has an expansion ratio of 1.2 to 20 and a bulk density of less than 1 g / cm ³ .
Moreover, in this pressure dispersion material, each component in the porous gel with respect to the total mass (A + B + C) of the polymer (A) of the water-soluble organic monomer, the clay mineral (B), and the low-volatile medium (C). Of the water-soluble organic monomer polymer (A) is 0.003 to 0.35, the clay mineral (B) is 0.002 to 0.15, and the low-volatile medium (C) is 0. It is preferable to be set to 0.5 to 0.995.
By setting the expansion ratio and bulk density of the porous gel and the blending ratio of each component within the above numerical ranges, the porous gel exhibits the following suitable moisture permeability / water absorption characteristics and mechanical characteristics.
That is, the moisture permeability of the porous gel is higher in the environment of 40 ° C. than the environment of 26 ° C. in the same relative humidity environment, and the relative humidity is 80% in the same temperature environment. The value is higher in an environment with a relative humidity of 30% than in the above environment.
The compressive stress at 30% displacement of the porous gel is 15 kPa or less, and the stress when the porous gel is compressed to 70% displacement or more and then returned to 50% displacement is 10 kPa or less.
In this pressure dispersion material, a polymer or copolymer of (meth) acrylamide and / or (meth) acrylamide derivatives is preferably used for the polymer (A) of the water-soluble organic monomer.
The low volatile medium (C) includes at least one selected from the group consisting of polyhydric alcohols, specifically glycerin, polyglycerin, polyethylene glycol, ethylene glycol and propylene glycol, and derivatives thereof. A monohydric alcohol is preferably used.

The present invention polymerizes and foams a water-soluble organic monomer dispersed in a dispersion together with a clay mineral (B) and a low-volatile medium (C) of 0.1 g / cm ² · hr · 60 ° C. · 1 atm or less. A method for producing a pressure dispersion material comprising a porous gel comprising a step, and polymerizing a water-soluble organic monomer dispersed in a dispersion containing water together with a clay mineral (B) to form a gel, A method for producing a pressure dispersion material comprising a porous gel comprising a step of substituting at least a part with a low-volatile medium (C) of 0.1 g / cm ² · hr · 60 ° C. · 1 atm or less and then foaming. Also provide.

The present invention provides a pressure dispersion material comprising an organic / inorganic composite polymer gel imparted with suitable load dispersibility.
The present invention also provides a pressure dispersion material comprising an organic / inorganic composite polymer gel imparted with characteristics suitable for skin physiological functions such as perspiration.

It is a schematic diagram explaining the shape of the dumbbell-type test piece evaluated in the Example.

Hereinafter, preferred embodiments for carrying out the present invention will be described. In addition, embodiment described below shows an example of typical embodiment of this invention, and, thereby, the range of this invention is not interpreted narrowly.

1. Pressure dispersion material (1) Water-soluble organic monomer polymer (A)
The pressure dispersion material according to the present invention is a porous gel containing a low-volatile medium (C) in a three-dimensional network formed from a polymer (A) of a water-soluble organic monomer and a clay mineral (B). Comprising.

The water-soluble organic monomer polymer (A) is preferably a polymer or copolymer of (meth) acrylamide and / or (meth) acrylamide derivatives. The polymer or copolymer of (meth) acrylamide and / or (meth) acrylamide derivatives is bonded to the clay mineral (B) dispersed in water by non-covalent bonds such as hydrogen bonds or ionic bonds, and a three-dimensional network is formed. Form.
Examples of (meth) acrylamide or derivatives thereof include N-substituted acrylamide derivatives, N, N-disubstituted acrylamide derivatives, N-substituted methacrylamide derivatives, and N, N-disubstituted methacrylamide derivatives. Specifically, acrylamide, N-methylacrylamide, N-ethylacrylamide, N-cyclopropylacrylamide, N-isopropylacrylamide, methacrylamide, N-methylmethacrylamide, N-cyclopropylmethacrylamide, N-isopropylmethacrylamide, N, N-dimethylacrylamide, N-methyl-N-ethylacrylamide, N-methyl-N-isopropylacrylamide, N-methyl-Nn-propylacrylamide, N, N-diethylacrylamide, N-acryloylpyrrolidine, N-acryloyl Examples include piperidin, N-acryloylmethyl homopiperazine, N-acryloylmethylpiperazine and the like. These monomers may be copolymers with other organic monomers.

Of these monomers, N-isopropylacrylamide, N, N-diethylacrylamide, etc., having polymer properties (hydrophilicity and hydrophobicity) in an aqueous solution having LCST (lower critical solution temperature) are preferable from the viewpoint of functionality.

In the pressure dispersion material according to the present invention, the pores formed in the porous gel are crushed during pressurization to change the shape, and when the pressurization is released, the pores are re-expanded to restore the voids. . In order to prevent the re-expansion of the pores from being inhibited by the close contact between the crushed pore surfaces, the monomer polymer may form a network having an appropriate interaction with the clay mineral. For this purpose, a copolymer obtained by combining a plurality of the above monomers is preferable.

(2) Clay mineral (B)
The clay mineral (B) is preferably one that swells in water or an aqueous solution, and more preferably one that can be exfoliated and dispersed finely and uniformly in a solution containing a water-soluble organic monomer. The clay mineral (B) is preferably dispersed at a nanometer level (thickness) of preferably 10 layers or less, more preferably 3 layers or less, and particularly preferably 1 layer or 2 layers.

The dispersion of the clay mineral (B) is confirmed by observing an ultrathin section of the dried porous gel with a transmission electron microscope. The diffraction angle (2θ) is preferably 3 ° to 8 °, more preferably 2 ° to 8 °, and particularly preferably 1 ° to 8 °. This is confirmed by the fact that no clear diffraction peak based on clay mineral stacking is observed.

Further, it is preferable that the clay mineral (B) is bonded to the water-soluble organic monomer polymer (A) by a non-covalent bond such as a hydrogen bond or an ionic bond to form a three-dimensional network. That is, the clay mineral (B) can form a three-dimensional network with the water-soluble organic monomer polymer (A) without using an organic crosslinking agent such as methylenebisacrylamide.

As the clay mineral (B), for example, a swellable inorganic clay mineral that swells in water such as water-swellable smectite or water-swellable mica and can be finely dispersed in a layered state is used. Specific examples include water-swellable hectorite containing sodium as an interlayer ion, water-swellable montmorillonite, water-swellable saponite, and water-swellable synthetic mica. In addition, if the layer can be peeled in a solvent together with the water-soluble organic monomer, a clay mineral partially organicized with a surfactant or the like can be used.

(3) Low volatile medium (C)
The low-volatile medium (C) is uniformly contained in the three-dimensional network composed of the water-soluble organic monomer polymer (A) and the clay mineral (B), and has a lower volatility than water. It is done.

The low volatile medium (C) is 0.1 g or less, preferably 0.05 g or less, more preferably 0.01 g or less, even more preferably 0.1 g or less per 1 cm ² / hour in an open system having a volatility of 60 ° C. and 1 atm. 0.001 g or less is used. Particularly preferred is one that hardly volatilizes at room temperature (10-30 ° C.).
Further, the low volatile medium (C) has a vapor pressure at 20 ° C. lower than that of water, and preferably has a vapor pressure at 20 ° C. of 1000 Pa or less, more preferably 100 Pa or less, more preferably 50 Pa or less. Things are used.
Further, the low volatile medium (C) has a boiling point higher than that of water at 1 atm, preferably has a boiling point at 1 atm of 130 ° C. or higher, more preferably 150 ° C. or higher, more preferably 170 ° C. or higher. Is used.
The low volatile medium (C) has a volatility of 0.1 g / cm ² · hr · 60 ° C. · 1 atm or less, a vapor pressure at 20 ° C. of 1000 Pa or less, and a boiling point at 1 atm of 130 ° C. or more. Is the best.

Examples of the low volatile medium (C) include polyhydric alcohols, polyhydric alcohol derivatives, ionic liquids, oils, and the like. Of these, hydrophilic and / or hygroscopic materials are suitable for exhibiting the moisture permeability described later, polyhydric alcohols and polyhydric alcohol derivatives are preferred, and polyhydric alcohols are particularly preferred. These substances can be used alone or in combination of two or more.

(3-1) Polyhydric alcohol Examples of the polyhydric alcohol include glycerin, polyglycerin (diglycerin, triglycerin, tetraglycerin, etc.), ethylene glycol, propylene glycol, polyethylene glycol (PEG 600, etc.), diethylene glycol, triethylene glycol. , Tetraethylene glycol, dipropylene glycol, 1,5-pentanediol (pentamethylene glycol), 1,2,6-hexanetriol, octylene glycol (ethohexadiol), butylene glycol (1,3-butylene glycol, 1,4-butylene glycol, 2,3-butanediol, etc.), hexylene glycol, 1,3-propanediol (trimethylene glycol), 1,6-hexanediol (hexamethylene glycol) Example). The volatility, vapor pressure, and boiling point of these polyhydric alcohols are shown in “Table 1”.

* Volatilization volume per 1cm ² · 1 hour in an open system at 60 ° C and 1atm. The unit is g / cm ² · hr · 60 ° C · 1 atm.

Of these polyhydric alcohols, glycerin, diglycerin, ethylene glycol, propylene glycol and polyethylene glycol are preferred, glycerin and diglycerin are more preferred, and glycerin is particularly preferred.

(3-2) Polyhydric alcohol derivatives Examples of the polyhydric alcohol derivatives include ester compounds and ether compounds of the polyhydric alcohols. For example, ethylene glycol monobutyl ether, ethylene glycol dibutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, ethylene glycol benzyl ether, ethylene glycol monoacetate, ethylene glycol diacetate, ethylene glycol monobutyl ether acetate, ethylene glycol monophenyl ether Acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol monoacetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomer Butyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monoacetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, triglycol dichloride, Examples thereof include 1-butoxyethoxypropanol, glyceryl monoacetate, glyceryl diacetate, glyceryl triacetate, glyceryl monobutyrate, glycerin ether, and poly (oxyethylene-oxypropylene) derivatives. The vapor pressure and boiling point of these polyhydric alcohol derivatives are shown in “Table 2”.

(3-3) Ionic liquid The ionic liquid is called an ionic liquid, a room temperature molten salt, or simply a molten salt, and is in a temperature range of 150 ° C. or lower, more preferably 100 ° C. or lower, particularly preferably 60 ° C. or lower. It is a salt that exhibits a liquid molten state.

In the present invention, the ionic liquid is roughly classified into a hydrophilic ionic liquid and a hydrophobic ionic liquid. In the present invention, water and an ionic liquid are mixed at a mass ratio of 1: 1, sufficiently stirred, allowed to stand, and separated into an aqueous phase and an ionic liquid phase within 10 minutes is defined as a hydrophobic ionic liquid. A substance having no phase separation observed after 10 minutes is defined as a hydrophilic ionic liquid. Whether the ionic liquid is hydrophilic or hydrophobic depends on the combination of cations and anions, slight differences in the structure of various cations, and the like.

Examples of the hydrophilic ionic liquid include the following.
As a cation, it has an ethyl methyl imidazole ion structure, and as an anion, chlorine ion, brom ion, thiocyanic acid, tetrafluoroboric acid, hexafluorophosphoric acid, trifluoromethanesulfonic acid, nitric acid, methylsulfonic acid ion structure, etc. An ionic liquid having
An ionic liquid having a butylmethylimidazole ion structure as a cation and a chloride ion, a bromide ion, a thiocyanic acid, tetrafluoroboric acid, trifluoromethanesulfonic acid, nitric acid, a methylsulfonic acid ion structure or the like as an anion.
An ionic liquid having a hexylmethylimidazolium or butyldimethylimidazolium ion structure as a cation and a chloride ion, a bromide ion, a thiocyanic acid, nitric acid, or a methylsulfonate ion structure as an anion.
As a cation, it has an ethyldimethylimidazole ion structure, and as an anion, a chloride ion, a bromide ion, a thiocyanic acid, a tetrafluoroboric acid, a hexafluorophosphoric acid, a trifluoromethanesulfonic acid, a nitric acid, a methylsulfonic acid ion structure, etc. An ionic liquid having
An ionic liquid having an ethylpyridinium ion structure as a cation and a chloride ion, a bromide ion, a thiocyanic acid, trifluoromethanesulfonic acid, nitric acid, or a methylsulfonic acid ion structure as an anion.

Examples of the hydrophobic ionic liquid include the following.
An ionic liquid having an ethylmethylimidazolium ion structure as a cation and a bis (trifluoromethylsulfonyl) imido ion structure as an anion.
An ionic liquid having a butyl methyl imidazole ion structure as a cation and a hexafluorophosphoric acid, bis (trifluoromethylsulfonyl) imido acid ion structure or the like as an anion.
The cation has a hexylmethylimidazole, hexylpyridinium ion structure, etc., and the anion has a tetrafluoroboric acid, hexafluorophosphoric acid, trifluoromethanesulfonic acid, bis (trifluoromethylsulfonyl) imido ion structure, etc. Ionic liquid.

More specifically, as the hydrophilic ionic liquid, 1-butyl-3-methylimidazolium methyl sulfate, 1-butyl-3-methylimidazolium thiocyanate, 1-ethyl-3-methylimidazolium ethyl sulfate, tetrabutylammonium Hydroxide 30-hydrate or the like is preferably used. Further, 1-butyl-3-methylimidazolium hexafluorophosphate is preferably used as the hydrophobic ionic liquid.

(3-4) Oil As the oil, known low volatility oils such as mineral oil, vegetable oil, animal oil and synthetic oil can be used singly or in combination of two or more.

Examples of mineral oil include liquid paraffin, liquid isoparaffin, naphthene oil, petroleum jelly, polydecene, hydrogenated polyisobutene, and the like.

Examples of vegetable oils include olive oil, olive squalane, macadamia nut oil, jojoba oil, castor oil, palm oil, palm oil, safflower oil, sunflower oil, hardened palm oil, hardened palm oil, almond oil, peanut oil, cottonseed oil, Avocado oil, apricot oil, grape seed oil, corn oil, soybean oil, rapeseed oil, sesame oil, apricot oil, shea butter oil, wheat germ oil, apricot oil, hazel oil, alfalfa oil, poppy oil, pumpkin oil, kidney bean oil, Examples include blackcurrant oil, evening primrose oil, millet oil, barley oil, quinoa oil, rye oil, kukui oil, passiflora oil and muskrose oil.

Examples of animal oils include lanolin, turtle oil, beeswax, squalene, pristane, perhydrosqualane and the like.

Synthetic oils include, for example, fatty acid triglycerides such as glycerin tri-2-ethylhexanoate; silicone oils such as polymethylphenylsiloxane, polydimethylsiloxane, phenylsilicone, aminosilicone; isopropyl myristate, octyldodecyl myristate, isononane Fatty acid esters such as isononyl acid, isopropyl palmitate, ethylhexyl palmitate, prusserine oil, isopropyl myristate, 2-ethylhexyl palmitate, 2-octyldodecyl stearate, 2-octyldodecyl erucate, isostearyl isostearate; Isostearyl lactate, octyl hydroxy stearate, octyl dodecyl hydroxy stearate, diisostearyl malate, triisocitrate Hydroxyl esters such as chill, heptanoic acid ester of fatty alcohol, octanoic acid ester, decanoic acid ester; polyol ester such as propylene glycol dioctanoate, neopentyl glycol diheptanoate, diethylene glycol diisononanoate; octyldeca For example, aliphatic alcohols such as diol, 2-butyloctanol, 2-hexyldecanol, 2-undecylpentadecanol and oleyl alcohol; higher fatty acids such as oleic acid, linoleic acid and linolenic acid; and the like.

(4) Blending ratio The polymer (A) of the water-soluble organic monomer is a total mass (hereinafter referred to as “total mass”) of the polymer (A) of the water-soluble organic monomer, the clay mineral (B), and the low-volatile medium (C). (A + B + C) ”) is preferably blended so that the mass ratio is 0.003 to 0.35, and is preferably blended so as to be 0.05 to 0.30. Further preferred. The clay mineral (B) is preferably blended so that the mass ratio with respect to the total mass (A + B + C) is 0.002 to 0.15, and is preferably blended so as to be 0.005 to 0.10. Is more preferable. The low volatility medium (C) is preferably blended so that the mass ratio with respect to the total mass (A + B + C) is 0.5 to 0.995, and is preferably 0.7 to 0.95. More preferably.

By setting the blending ratio of each composition within the above numerical range, the porous gel can be provided with suitable mechanical properties such as moisture permeability / water absorption characteristics and load dispersibility described below.

(5) Additives The porous gel used in the pressure dispersion material according to the present invention may contain the following substances. These additives are preferably preliminarily mixed with the water-soluble organic monomer at the time of production of the gel foam, and in some cases can be injected into the foam after foaming.

(5-1) Hydrophilic polymer compound As the hydrophilic polymer compound, a natural, semi-synthetic or synthetic hydrophilic polymer compound may be contained alone or in combination of two or more. By blending the hydrophilic polymer compound, volatilization of water can be suppressed when water is included in the gel. From the viewpoint of long-term use as a pressure dispersion material and durability, the hydrophilic polymer compound is preferably one that is difficult to disintegrate or dissolve even when contacted with water by controlling the number of crosslinks or hydrophilic functional groups. The thing of nature is further preferable. The hydrophilic polymer compound is preferably added in an amount of 0.1 to 50% by mass, more preferably 1 to 20% by mass, in the gel foam.

Specific examples of natural hydrophilic polymer compounds include plant systems such as gum arabic, gum tragacanth, galactan, guar gum, carob gum, caraya gum, carrageenan, pectin, agar, starch (eg, rice, corn, potato and wheat starch). Polymers: Microbial polymers such as xanthan gum, dextrin, dextran, succinoglucan and pullulan; animal polymers such as casein, albumin and gelatin.

Specific examples of the semi-synthetic hydrophilic polymer compound include, for example, starch-based polymers such as carboxymethyl starch and methylhydroxypropyl starch; methylcellulose, ethylcellulose, methylhydroxypropylcellulose, hydroxyethylcellulose, sodium cellulose sulfate, hydroxypropylcellulose, carboxy Cellulose polymers such as methylcellulose and carboxymethylcellulose / sodium; and alginic acid polymers such as sodium alginate and propylene glycol alginate.

Specific examples of the synthetic hydrophilic polymer compound include, for example, vinyl polymers such as polyvinyl alcohol, polyvinyl methyl ether, polyvinyl pyrrolidone and carboxyvinyl polymer; acrylic polymers such as sodium polyacrylate and polyacrylamide; polyethyleneimine and the like Is mentioned.

(5-2) Filler, etc. Conventionally known inorganic fillers, liquid fillers, flame retardants, fibrous reinforcing materials, colorants and the like can be contained. Further, a volatile medium such as water used in the process of producing the gel foam of the present invention may be contained. When water is contained, the gel foam contains 0.1 to 60% by mass. It is preferable to add 1 to 40% by mass.

(6) Foaming ratio / pore diameter The pressure dispersion material according to the present invention contains pores in the gel, thereby reducing the density while maintaining the stretchability and exhibiting high flexibility. The size of the pores formed in the gel, the type and shape of the independent pores / continuous pores, etc. are not particularly limited.

The foaming ratio of the porous gel used in the pressure dispersion material according to the present invention is the foaming of the dispersion containing the water-soluble organic monomer polymer (A), the clay mineral (B), and the low-volatile medium (C). It is 1.2 to 20, preferably 1.5 to 10 with respect to the previous volume. If the expansion ratio was above range, the bulk density of the porous gel is less than 1 g / cm ^3, preferably ^{0.05g / cm 3 ~ 0.9g / cm} 3, more preferably 0.1 g / ^cm 3 ~ 0.7 g / cm ³ , particularly preferably 0.15 to 0.5 g / cm ³ .
The average pore diameter of the pores formed by foaming is preferably 1 to 1000 μm, more preferably 5 to 500 μm, still more preferably 10 to 300 μm, and particularly preferably 20 to 200 μm.

By setting the expansion ratio, the bulk density, and the average pore diameter of the pores within the above numerical ranges, the porous gel has the following suitable moisture permeability / moisture absorption characteristics and dynamics such as load dispersibility, compressive stress, and elongation under load. Characteristics can be imparted. Specifically, when the expansion ratio of the porous gel or the average pore diameter of the pores is smaller than the lower limit value of the numerical range (when the bulk density is larger than the upper limit value of the numerical range), it is difficult to provide sufficient moisture permeability. If the expansion ratio or the average pore diameter of the pores is larger than the upper limit value of the above numerical range (if the bulk density is smaller than the lower limit value of the numerical range), sufficient load dispersibility and durability are difficult to be imparted.

(7) Moisture permeability / moisture absorption characteristics The porous gel used in the pressure dispersion material according to the present invention has a blending ratio of each composition, an expansion ratio (bulk density), and an average pore diameter within a predetermined range. Exhibits suitable moisture permeability and moisture absorption characteristics.
The moisture permeability of the porous gel is the same in the relative humidity environment (for example, 30RH%, 50RH%, or 80RH%) in the environment where the temperature is 40 ° C rather than the environment where the temperature is 26 ° C. Is preferably high. In this case, the moisture permeability of the porous gel in an environment at a temperature of 26 ° C. is preferably 100 to 2500 g / m ² · day, and the moisture permeability of the porous gel in an environment at a temperature of 40 ° C. is 1000 to 5000 g / day. m ² · day is preferable.
In addition, the moisture permeability of the porous gel is 30% relative humidity than 80% relative humidity in the same temperature environment (for example, any environment of 26 ° C., 32 ° C., or 40 ° C.). It is preferable that the lower one has a higher value. In this case, the moisture permeability of the porous gel in an environment with a relative humidity of 80% is preferably 100 to 2500 g / m ² · day, and the moisture permeability of the porous gel in an environment with a relative humidity of 30% is 1000 to It is preferably 5000 g / m ² · day.
As described above, the porous gel of the present invention changes in moisture permeability characteristics depending on the temperature and humidity environment. For example, in an environment where the relative humidity is 30% and the temperature is 40 ° C., the moisture permeability is 3000 to 5000 g / hr. m ² · day is preferable, and in an environment where the relative humidity is 50% and the temperature is 32 ° C, the moisture permeability is preferably 1000 to 3000 g / m ² · day, and the relative humidity is 80% and the temperature is 26 ° C. Then, the moisture permeability is preferably 100 to 1000 g / m ² · day.
Furthermore, after the porous gel of the present invention is left for 24 hours in an environment with a relative humidity of 30%, the water retained in the gel is released and the gel mass decreases, and the porous gel is left for 24 hours in an environment with a relative humidity of 80%. It is preferable to increase the gel mass by absorbing ambient moisture later.
Specifically, the porous gel of the present invention is allowed to stand for 24 hours in an environment with a relative humidity of 30% under the same temperature environment (for example, any environment of 26 ° C., 32 ° C., or 40 ° C.). The gel mass is preferably reduced by 1 to 30%, more preferably 2 to 25%. In addition, the porous gel of the present invention has a gel mass after being left for 24 hours in an environment with a relative humidity of 80% under the same temperature environment (for example, any environment of 26 ° C., 32 ° C., or 40 ° C.). It is preferably increased by 5 to 50%, more preferably increased by 10 to 40%.

Since the pressure dispersion material of the present invention has the moisture permeability / moisture absorption characteristics as described above, when sweating or insensitive steaming increases at high temperatures and high humidity, it absorbs and emits excess moisture. In addition, it eliminates discomfort and skin damage due to stuffiness, and emits moisture to dry skin when dried, etc., so that skin improvement by moisturizing action can be expected. As described above, the pressure dispersion material of the present invention can maintain homeostasis and comfort of skin physiological functions even when used for a long time. In addition, when the moisture permeability of a pressure dispersion material is too high, load dispersibility may become inadequate or durability of a porous gel may fall. On the other hand, if the moisture permeability is too low, discomfort due to stuffiness or the like tends to occur.

It is considered that the porous gel retains moisture in the voids of the formed pores and the low-volatile medium, and releases moisture through the voids of the pores due to environmental changes such as temperature and humidity. In the porous gel used for the pressure dispersion material according to the present invention, the expansion ratio is 1.2 to 20 (bulk density is less than 1 g / cm ³ ), and the average pore diameter is 1 to 1000 μm, more preferably 5 to By adjusting to 500 μm, it is considered that such moisture absorption and sustained release properties are adjusted so that the above-described suitable moisture permeability and moisture absorption characteristics can be exhibited.

In addition, when the low volatile medium (C) included in the composition is a polyhydric alcohol or a derivative thereof, the porous gel retains moisture due to its affinity with water such as polyhydric alcohol, and absorbs moisture gradually. It is thought that it shows. In the porous gel used for the pressure dispersion material according to the present invention, the mass ratio (C) / {(A) + (B) + (C)} of the low volatile medium (C) is 0.5 to 0.995. And more preferably 0.7 to 0.95, and by adjusting the hygroscopic sustained release property due to hydrophilicity, the above-mentioned preferable moisture permeability is exhibited.

(8) Load dispersibility The porous gel used for the pressure dispersion material according to the present invention exhibits suitable load dispersibility by setting the expansion ratio and the like within a predetermined range. The pressure dispersion material according to the present invention has a maximum pressure of preferably 160 mmHg or less, more preferably 130 mmHg or less when used as a cushion material for a mattress for bedding, a chair or a wheelchair as a sheet having a thickness of 50 mm. Note that the maximum pressure when the pressure dispersion material is not used is usually 200 mmHg or more. The pressure dispersion material according to the present invention exhibits a good load dispersibility of about 110 mmHg.

Since the pressure dispersion material of the present invention has such suitable load dispersibility, pressure absorption of pressure ulcer prevention tools and various appliances in medical and daily life fields such as orthopedics, surgery, rehabilitation, nursing, nursing care, sports, etc. It is suitable as a pressure dispersion material used for a pad or the like. If the load dispersibility of the pressure dispersion material is insufficient, it may cause skin damage (in some cases pressure sores) due to local stress concentration, or damage to bones, joints, and the like.

The porous gel exhibits load dispersibility by changing the shape by crushing the pores during pressurization. In the porous gel used for the pressure dispersion material according to the present invention, it is preferable that the expansion ratio is 1.2 to 20 (bulk density is less than 1 g / cm ³ ) and the load dispersibility is adjusted to the above numerical range. Body pressure dispersion performance is demonstrated.

In the porous gel used for the pressure dispersion material according to the present invention, the polymer (A) of the water-soluble organic monomer, the clay mineral (B), and the low-volatile medium (C) are blended at a predetermined ratio, and the porous gel is used. By adjusting the elasticity and recoverability of the gel, suitable body pressure dispersion performance is exhibited.

(9) Other properties (9-1) Compressive stress The pressure dispersion material of the present invention is a pressure absorbing material for pressure ulcer prevention devices and various appliances in the fields of medical and daily life such as orthopedics, surgery, rehabilitation, nursing, nursing care and sports. In addition to load dispersibility suitable as a pressure dispersion material used for a pad or the like, it exhibits good shock absorption and load support. Specifically, the compressive stress at 30% displacement of the pressure dispersion material is preferably 15 kPa or less, and more preferably 0.5 to 10 kPa. The stress when the pressure dispersion material is compressed by 70% displacement or more and then returned to 50% displacement is preferably 10 kPa or less, more preferably 0.1 to 8 kPa.
The pressure dispersion material of the present invention can relieve stress in the compression direction by exhibiting the above-mentioned predetermined characteristics, and can also have load supportability.

(9-2) Viscoelastic properties The pressure dispersion material of the present invention desirably has shear stress dispersibility peculiar to gel materials, more specifically, shear stress dispersibility expressed by the softness and viscoelastic properties of the gel itself. . Specifically, the porous gel used in the pressure dispersion material of the present invention has a complex elastic modulus | G * | of 1.0 to 10.0 kPa at 37 ° C. and a strain rate of 1.0 Hz, and a loss tangent tan δ of 0.1. It is preferably 01 to 1.00, the complex elastic modulus | G * | is preferably 0.8 to 8.0 kPa, and the loss tangent tan δ is more preferably 0.05 to 0.50. Further, the pressure dispersion material of the present invention has a complex elastic modulus | G * | of 1.0 to 10.0 kPa at 37 ° C. and a strain rate of 0.1 to 10.0 Hz, and a loss tangent tan δ of 0.01 to 1. 00 is preferable.
The pressure dispersion material of the present invention can relieve the stress in the shearing direction applied to the skin surface and the inside by exhibiting the above-mentioned predetermined viscoelastic characteristics, and can also have load supportability.

(9-3) Elongation force / Elongation rate The porous gel used in the pressure dispersion material of the present invention applies stress to the skin when a deformation force is applied when the pressure dispersion material is attached or when a body load is applied. It is preferable that the extension force at 100% extension is 50 kPa or less.
The porous gel used in the pressure dispersion material of the present invention preferably has an elongation rate of 100% or more at a load of 30 kPa in order to enhance adhesion to the body surface.

(9-4) Seating Temperature and Humidity The pressure dispersion material of the present invention can adjust the body surface environment to a comfortable environment. The temperature / humidity range considered to be comfortable in a general clothing environment is an environment having a humidity of less than 65 RH% at a temperature of 30.5 to 33.5 ° C., more preferably 40 to 60 RH% at 31 to 33 ° C. The condition is considered to be the same between the human body surface and the wearing object. The porous gel used in the present invention can keep the environment between the human body surface and the porous gel in this comfortable environment by having the moisture absorption and sustained release property described above. When the pressure dispersion material of the present invention is used as a wheelchair cushion, the temperature / humidity around the rupture of the seating part is maintained at a temperature of 31-32 ° C. and a humidity of 50-55% RH, and a comfortable temperature / humidity state can be maintained. It is.

2. Manufacturing method of pressure dispersion material The manufacturing method of the pressure dispersion material according to the present invention is a water-soluble material dispersed in a dispersion together with a clay mineral and a low-volatile medium of 0.1 g / cm ² · hr · 60 ° C · 1 atm or less. It comprises a porous gel comprising steps of polymerizing and foaming organic monomers.

Specifically, in the process of polymerizing a water-soluble organic monomer in the presence of a clay mineral that has been exfoliated and uniformly dispersed in a solvent (water and a low-volatile medium), the water-soluble organic monomer and the clay mineral A foaming agent or a gas is introduced into a mixture of the solvent and the solvent, polymerized and foamed. Alternatively, the water-soluble organic monomer may be foamed by introducing a foaming agent or a gas into the solvent after polymerization. In the solvent, a polymerization initiator, a catalyst, and other water-soluble compounds (additives) may be mixed and dissolved in advance.
Further, the method for producing a pressure dispersion material according to the present invention introduces a water-soluble organic monomer and a foaming agent into a dispersion containing water together with a clay mineral, polymerizes the water-soluble organic monomer, forms a gel, It comprises a porous gel including a step of foaming after substituting at least a part of it with a low-volatile medium of 0.1 g / cm ² · hr · 60 ° C. · 1 atm or less.
Specifically, in the process of polymerizing a water-soluble organic monomer in the presence of a clay mineral that has been exfoliated and uniformly dispersed in a solvent (water), foaming occurs in a mixture of the water-soluble organic monomer, the clay mineral, and water. After introducing the agent and polymerizing the water-soluble organic monomer, at least a part of the water is replaced with a low-volatile medium, and then foamed by heating or the like. In the solvent, a polymerization initiator, a catalyst, and other water-soluble compounds (additives) may be mixed and dissolved in advance.

As the foaming agent, low boiling point hydrocarbon compounds such as heptane, pentane, cyclopentane and hexane, chlorinated hydrocarbon compounds, chlorofluorocarbons, carbonates such as NaHCO ₃ , Na ₂ CO ₃ and CaCO ₃ are preferable. In particular, hydrocarbon compounds and carbonates are particularly preferably used because they are easy to operate and have little influence on the environment. The addition amount of the foaming agent varies depending on the foaming ratio of the desired foam, the type of foaming agent used, and the foaming conditions (eg, temperature and pressure), and is appropriately selected. For example, in the case of pentane, 50 to 1000% by mass is preferably used with respect to the water-soluble organic monomer and clay mineral. For example, when pentane is used as the foaming agent, pentane is added with stirring during the polymerization process to prepare a gel. When the obtained gel is held in the air at room temperature or as needed, foaming occurs and a uniform gel foam can be obtained.

The gas is preferably an inert gas, and examples thereof include nitrogen gas and carbon dioxide gas. The amount of gas introduced is also appropriately selected depending on the desired foaming ratio of the foam. In the case of using a gas, for example, nitrogen gas is introduced in the polymerization process, preferably so as to form fine bubbles when the viscosity rises to 30 mPa · s or more, and polymerized to obtain a gel foam.
As the foaming agent, a microcapsule having a property of expanding by heat is effectively used. Specific examples of thermally expandable microcapsules include thermoplastic polymers (eg, polymethyl methacrylate, polyglycolic acid, etc.) and their crosslinked polymers as shells, and low-boiling hydrocarbons inside them. A microcapsule wrapped around Such thermally expandable microcapsules are introduced into a reaction solution for gel preparation, and then, after the polymerization process and / or polymerization, are preferably thermally expanded and expanded in an organic-inorganic composite gel containing a low-volatile medium. It becomes a capsule and has the function of making the gel into a foamed state. The size of the thermally expandable microcapsule to be used is not necessarily limited, but in order to be finely dispersed and contained in the three-dimensional network in the gel, it is 1 to 500 μm, more preferably 3 to 100 μm, and particularly preferably 5 to 50 μm. The size of the range is used. The amount of thermally expandable microcapsules used varies depending on the desired expansion ratio, the type of thermally expandable microcapsules used, and the conditions during expansion (foaming) (eg, temperature and pressure). The mass ratio with respect to the organic monomer is preferably in the range of 0.01 to 10. On the other hand, as the temperature causing the expansion, a range that does not inhibit the synthesis of the organic-inorganic composite gel is used. For example, the expansion temperature is preferably equal to or higher than the polymerization temperature of the gel, specifically, a range of 20 ° C. to 250 ° C. is used, more preferably 30 ° C. to 200 ° C., still more preferably 50 ° C. to 150 ° C. Particularly preferably, a range of 60 ° C. to 120 ° C. is used. Specific examples of thermally expandable microcapsules that can be used in the present invention include Matsumoto Microsphere F series (Matsumoto Pharmaceutical Co., Ltd .: F-20, F-30, F-36LV, F-36, F-48). , F-50, F-78K, F-79, F-80S, F-82, F-100, F-102, F-105, F-170, F-190D, F-230D, F-260D, etc. FN-series (Matsumoto Pharmaceutical Co., Ltd .: FN-100, FN-105, FN-180S, FN-180, etc.).

Example 1
19.8 g of N, N-dimethylacrylamide (manufactured by Kojin Co., Ltd.) as the water-soluble organic monomer, 4.58 g of water-swellable hectorite (trademark Laponite XLG, manufactured by Rockwood Co., Ltd.) as the swellable clay mineral, A uniformly transparent solution containing 14.85 g (dry weight) of a heat-expandable microcapsule (F20: Matsumoto Yushi Seiyaku Co., Ltd., average particle size: 10 to 20 μm) and 190 g of pure water was prepared in a 500 ml glass container with stirring. . The solution was placed in an ice bath, and then 10 g of an aqueous initiator solution containing 0.2 g of potassium peroxodisulfate was added with stirring to obtain a homogeneous reaction solution. Next, the reaction solution is poured into a glass container for film production (internal volume 60 cm ³ : length 10 cm, width 10 cm, thickness 6 mm), and the glass container is placed in a constant temperature water bath at 50 ° C. and held for 5 hours to remove the water-soluble organic monomer. Polymerization was performed to prepare an organic-inorganic composite gel. The mass ratio of thermally expandable microcapsule / water-soluble organic monomer polymer is 0.75. The above steps were all performed in a state where oxygen was removed. After the polymerization, the organic-inorganic composite gel taken out from the container was placed in a large excess (about 5 times the amount of the gel) of a mixed solution of glycerin and water (glycerin: water = 71: 29 (mass ratio)). Held for hours. Meanwhile, the fresh mixed solution was exchanged every 12 hours. A part of the obtained organic-inorganic composite gel was cut out and the amount of glycerin contained was measured by dry weight and thermogravimetric analysis. The mass ratio of glycerin to (polymer + clay (hectorite) + glycerin) was 0. The mass ratio of polymer and clay to (polymer + clay (hectorite) + glycerin) was 0.088 and 0.02, respectively. This organic-inorganic composite gel was treated in an autoclave at a temperature of 105 ° C. for 20 minutes to expand the thermally expandable microcapsules and obtain a foamed gel. Furthermore, the organic-inorganic composite porous gel was obtained by performing humidity control by holding for 1 day in an atmosphere of 60% humidity and 25 ° C. temperature. The mass ratio of water / glycerin in the medium of the obtained organic-inorganic composite porous gel was 0.2. Moreover, the volume ratio (foaming ratio) of the organic-inorganic composite porous gel to the organic-inorganic composite gel before foaming (expansion) is 3.6, and the density of the organic-inorganic composite porous gel is 0.30 g / cm ³ , average The pore diameter was 51 μm. The obtained organic-inorganic porous gel was a lightweight gel porous body that was flexible, had surface tackiness, and was excellent in handleability. The organic / inorganic porous gel was cut into a rectangular parallelepiped having a length of 2 cm and a thickness of 1 cm, and a stretching test was performed by cutting into a rectangular parallelepiped having a cross section of 1 cm × 1 cm and a length of 7 cm. The compression and stretching tests were performed using a desktop universal testing machine AGS-H manufactured by Shimadzu Corporation at deformation speeds of 30 mm / min and 50 mm / min. As a result, 90% compression (compression up to 10% of the original length) in the compression test does not break, and even in the stretching test, it does not break even if stretched to 200%. Was possible. The stress at 60% compression was 21 kPa for the first time and 18 kPa for the second time and thereafter. On the other hand, the obtained organic-inorganic porous gel showed a stable shape and physical properties in the air for a long period (one year or more).

(Example 2)
An organic-inorganic composite gel was prepared in the same manner as in Example 1 except that 130 g of pure water and 60 g of glycerin were used instead of 190 g of water. The glycerin content in the medium in the obtained gel was 30%. This organic-inorganic composite gel was treated in a thermostat at a temperature of 80 ° C. and a humidity of 95% for 120 minutes to expand the thermally expandable microcapsules, thereby obtaining an organic-inorganic composite porous gel. The mass ratios of glycerin, polymer and clay mineral to (glycerin + polymer + clay mineral) in the obtained organic-inorganic composite porous gel were 0.711, 0.235 and 0.05, respectively. The foaming ratio of the organic-inorganic composite porous gel was 4.0 times, and the density was 0.27 g / cm ³ . Reversible repetitive deformation was possible in each of the compression tests without breaking even when compressed by 90% or even when stretched to 200% in the stretching test. The stress at 60% compression was 29 kPa.

(Example 3-5)
An organic-inorganic composite porous gel shown in “Table 3” was prepared in the same manner as in Example 1 except that the mass ratio of each component and the mass ratio of the thermally expandable microcapsule to the monomer were changed.

Each characteristic of the organic-inorganic composite porous gel according to the above example was evaluated by the following method.

(Moisture permeability)
(1) Sample adjustment The porous gel was cut into a sheet having a thickness of 5 mm and adjusted for 24 hours or more in an environment of a temperature of 23 ± 2 ° C. and a relative humidity of 65 ± 5%.
(2) Test method Measured according to JIS K6404 and JIS L1099 A-2 “Water Method”.
About 42 ml of water at the measurement environment temperature is put in a moisture permeable cup that has been adjusted to the measurement environment temperature in advance, and a sheet-like porous gel test piece, packing, and ring are placed on the moisture permeable cup in order, and fixed with a butterfly nut. Is sealed with vinyl adhesive tape.
Specimens total mass including the moisture-permeable cup (moisture-permeable cup, porous gel specimen, packing, rings, and the total mass of the wing nut) was measured, and the initial specimen total mass C _0.
Temperature 26 ° C., 32 ° C., respectively 30% relative humidity at 40 ° C., 50%, the specimen total mass _{C 2} after exposure to moisture permeation cup 2 hours under 80% of the test environment was measured, starting further tested After 24 hours, the total mass C ₂₄ of the test specimen was measured, and the moisture permeability was calculated according to the following formula.
T = ((C ₂ -C ₂₄ ) / S) × 24/22
T: Moisture permeability [g / m ² · day]
C ₂ : Mass of test specimen 2 hours after start of measurement [g]
C ₂₄ : Mass of test specimen 24 hours after start of measurement [g]
S: Moisture permeable area of cup [m ² ]

(Mass change rate of porous gel)
(1) Sample adjustment Measurement is performed using a sheet-like porous gel test piece used in the above-mentioned "moisture permeability" test.
(2) Test method As in the above test of “moisture permeability”, a porous gel sample adjusted for 24 hours or more in an environment of a temperature of 23 ± 2 ° C. and a relative humidity of 65 ± 5% is set in a moisture permeable cup. The total mass of the test specimen including the wet cup (the total mass of the moisture permeable cup, the porous gel test piece, the packing, the ring, and the wing nut) is measured to determine the total mass C ₀ of the initial specimen.
Thereafter, at a temperature of 26 ° C., 32 ° C., and 40 ° C., the total mass C ₂₄ of the test body after the moisture permeable cup was exposed for 24 hours in each test environment of 30%, 50%, and 80% relative humidity, The mass change rate of the porous gel was calculated according to the following formula.
R = ((C ₂₄ -C ₀ ) / C ₀ )
R: Mass change rate of porous gel (%)
C ₀ : initial test specimen total mass before starting measurement [g]
C ₂₄ : Mass of test specimen 24 hours after start of measurement [g]

(Compressive stress)
(1) Sample adjustment It adjusted for 24 hours or more in the environment of temperature 23 +/- 2 degreeC and relative humidity 65 +/- 5%.
(2) Test method Based on JISK6400-2, a test piece having a thickness of 50 mm or more was carried out at a test speed of 10 mm per minute. Using a tensile tester (trade name “Autograph AG-I”, manufactured by Shimadzu Corporation), the test piece is compressed to a displacement equivalent to 70% or more in terms of the percentage starting from the thickness of the original test piece. Then, the test force at each displacement of the operation of returning to the original thickness was measured.
(A) Compressive stress at 30% displacement Value obtained by dividing the test force when the test piece is compressed to a displacement equivalent to 30% by the percentage starting from the thickness of the original test piece, by the area of the test piece before starting the test. Was calculated as “30% compressive stress”.
(B) Stress when compressed to 70% displacement or more and then returned to 50% displacement. After applying compression more than 70% displacement at a percentage starting from the thickness of the original test piece, The test force when returning to 50% displacement was measured, and the value divided by the test piece area before the start of the test was calculated as “return 50% compressive stress”.

(Viscoelastic properties)
(1) Sample adjustment The porous gel was cut into a sheet having a thickness of 5 mm and adjusted for 24 hours or more in an environment of a temperature of 23 ± 2 ° C. and a relative humidity of 65 ± 5%.
(2) Test method Dynamic viscoelasticity was measured using a viscoelasticity measuring device (manufactured by HAAKE, trade name “Rheo Stress RS150”). The complex elastic modulus and loss tangent when the strain rate (frequency) is changed from 0.01 to 100.0 (1 / s) under the conditions where the measurement temperature is 37 ° C. and the stress is 100 (Pa). Measurements were made.

(Elongation rate / Elongation force)
(1) Sample preparation The porous gel was removed from the shape of the dumbbell-shaped test piece shown in FIG. 1 with a thickness of 5 mm, and was adjusted for 24 hours in an environment of a temperature of 32 ° C. and a relative humidity of 50%.
(2) Test method According to JIS K 6251 “Vulcanized rubber and thermoplastic rubber-Determination of tensile properties”, the above-mentioned dumbbell-shaped test piece was stretched at a load of 0.75 N (30 kPa) (%) and 100 The elongation force at% elongation was measured using a tensile tester (Instron, trade name “INSTRON 5564”) under the conditions of a tensile speed of 100 mm / min and a distance between chucks of 20 mm. The cross-sectional area between the gauge points at the time of load or extension is 25 mm ² .

The evaluation results are shown in “Table 4”.

Using the porous gel of Example 1, a practical test as a pressure dispersion material was performed as follows.

(Load dispersibility)
The pressure dispersion material of the present invention having a thickness of 50 mm was used as a cushioning material for a standard wheelchair, and the maximum pressure when a healthy person was seated was measured with a pressure distribution measuring device (VERS (Canada) FSA). Similarly, a 75 mm thick urethane foam wheelchair cushion, a 50 mm thick low-resilience urethane foam cushion, and a 25 mm thick urethane gel pad, which are commercially available highly breathable cushion materials, were similarly tested and compared.

(Sitting temperature and humidity)
The test was carried out in an indoor environment at a temperature of 28 ° C. and a relative humidity of 65%.
Using the pressure dispersion material of the present invention having a thickness of 50 mm as a cushioning material for a standard type wheelchair, the temperature and humidity around the rupture of the seating part when a healthy person continues to sit for 1 hour is a thermohygrometer (manufactured by Sato Keiki Seisakusho) It was measured by “digital thermohygrometer SK-110TRH TYPE4”). Similarly, a 75 mm thick urethane foam wheelchair cushion, a 50 mm thick low-resilience urethane foam cushion, and a 25 mm thick urethane gel pad, which are commercially available highly breathable cushion materials, were similarly tested and compared.

The results are shown in “Table 5”.

From the above results, the pressure dispersion material of the present invention has suitable mechanical properties (load dispersibility, compressive stress, elongation rate, elongation force, etc.) as the pressure dispersion material as described above, and has the physiological function of skin. It also has moisture permeability and moisture absorption characteristics that are considered desirable for homeostasis and comfort, and is useful as a pressure dispersion material for use on the human body.

The pressure dispersion material according to the present invention has suitable load dispersibility and moisture permeability / water absorption characteristics. Therefore, it can be suitably used as a pressure-absorbing pad for pressure ulcer prevention tools and various appliances in medical and daily life fields such as orthopedics, surgery, rehabilitation, nursing, nursing care, and sports.

Claims (14)

1. Low volatile medium (C) of 0.1 g / cm ² · hr · 60 ° C · 1 atm or less in a three-dimensional network formed from a polymer (A) of a water-soluble organic monomer and a clay mineral (B) A pressure dispersion material comprising a porous gel containing
2. A low-volatile medium having a vapor pressure of 1000 Pa or less at 20 ° C. and a boiling point of 130 ° C. or more at 1 atm in a three-dimensional network formed from a polymer (A) of a water-soluble organic monomer and a clay mineral (B) A pressure dispersion material comprising a porous gel containing (C).
3. The pressure dispersion material according to claim 1 or 2, wherein the foaming ratio of the porous gel is 1.2 to 20.
4. The pressure dispersion material according to any one of claims 1 to 3, wherein a bulk density of the porous gel is less than 1 g / cm ³ .
5. The mass ratio of each component in the porous gel to the total mass (A + B + C) of the polymer (A), the clay mineral (B), and the low-volatile medium (C) of the water-soluble organic monomer,
   The water-soluble organic monomer polymer (A) is 0.003 to 0.35,
   The clay mineral (B) is 0.002 to 0.15,
   The pressure dispersion material according to any one of claims 1 to 4, wherein the low volatile medium (C) is 0.5 to 0.995.
6. The moisture permeability of the porous gel is higher in an environment at a temperature of 40 ° C than in an environment at a temperature of 26 ° C under the same relative humidity environment. Pressure dispersion material.
7. The moisture permeability of the porous gel is higher in an environment having a relative humidity of 30% than in an environment having a relative humidity of 80% under the same temperature environment. Pressure dispersion material.
8. The pressure dispersion material according to any one of claims 1 to 7, wherein a compressive stress at 30% displacement of the porous gel is 15 kPa or less.
9. The pressure dispersion material according to any one of claims 1 to 8, wherein a stress when the porous gel is compressed to 70% displacement or more and then returned to 50% displacement is 10 kPa or less.
10. The pressure dispersion material according to any one of claims 1 to 9, wherein the polymer (A) of the water-soluble organic monomer is a polymer or copolymer of (meth) acrylamide and / or (meth) acrylamide derivatives. .
11. The pressure dispersion material according to any one of claims 1 to 10, wherein the low-volatile medium (C) is a polyhydric alcohol.
12. The pressure dispersion material according to claim 11, wherein the polyhydric alcohol is one or more selected from the group consisting of glycerin, polyglycerin, polyethylene glycol, ethylene glycol, propylene glycol, and derivatives thereof.
13. Porous process including polymerizing and foaming a water-soluble organic monomer dispersed in a dispersion together with a clay mineral (B) and a low volatile medium (C) of 0.1 g / cm ² · hr · 60 ° C. · 1 atm or less For producing a pressure dispersion material comprising a gel.
14. After polymerizing a water-soluble organic monomer dispersed in a dispersion containing water together with the clay mineral (B) to form a gel, at least part of the water is 0.1 g / cm ² · hr · 60 ° C · 1 atm or less A method for producing a pressure dispersion material comprising a porous gel comprising a step of substituting with a low-volatile medium (C) and then foaming.

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