JP2000143739A - Moisture-absorbing and heat-generating sheet like material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject sheet like material equipped with a touch such as resilience, firmness, etc., and having a function of absorbing moisture in a high moisture-absorbing rate and instantly generating heat by loading specific polymer particles on the surface of a specific fibrous material. SOLUTION: This moisture-absorbing and heat-generating sheet like material is obtained by loading polymer particles of an acrylate-modified (meth)acrylic polymer having <=5 μm, preferably <=1 μm mean particle diameter, a cross- linking structure, 5-12 eq/g salt type carboxyl group on the surface of a fibrous material constituting a sheet like material. As the sheet like material, it means the material having a two dimensional planar state material having a thin thickness, and e.g. a cloth, paper, knitted/woven fabrics, non-woven cloth, sheet, etc., are cited. As the fibrous material as the constituting component of the sheet like material, the fibrous material consisting of an organic/inorganic polymer, glass, metal, etc., are cited. As the cross-linking structure of the (meth) acrylic polymer, those obtained by introducing with copolymerizing divinylbenzene, etc., are cited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet-like material having a function of absorbing moisture and generating heat with it, and releasing the moisture again to repeat the function. More specifically, the present invention relates to a sheet-like material capable of repeating moisture absorption and heat generation, in which constituent fibers of the sheet-like material such as a nonwoven fabric carry a moisture-absorbing and heat-generating material.

[0002]

2. Description of the Related Art Recently, there has been an increasing demand for comfortable living environment for people, and development of materials having high antistatic function, antibacterial function and moisture absorbing function has been promoted. Regarding the moisture absorption function, for example, Japanese Patent Application Laid-Open No. 5-132858 discloses a technique of a fiber having both moisture absorption and moisture release properties. In addition, Japanese Unexamined Patent Publication No.
Japanese Patent Application Laid-Open No. 294006 discloses an invention relating to a moisture-absorbing / desorbing, water-absorbing, heat-generating heat insulation product in which the above-mentioned fiber is used for a middle ground and a surface material and a lining are attached thereto.

[0003] The heat insulation product disclosed in the latter publication generates heat,
In terms of the provision of warm clothing, it contributes to the comfort of human life, but it has three layers: front, middle and lining, and is difficult to handle and can only be applied to specific applications. There is. Further, in the case of the cloth made of only the middle ground of the heat-retaining product, that is, only the fiber of the above-mentioned publication, the waist and the tension of the cloth are poor, or the speed of absorbing moisture is low, and the human body may have a feeling of warmth due to sufficient heat generation. There are drawbacks such as not being removed.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and has a function of absorbing moisture at a high moisture absorption rate with a feeling such as waist and tension and immediately generating heat. It is intended to provide a sheet-like material.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet material having a crosslinked structure and a salt type carboxyl group of 5 to 12 meq / g on the surface thereof. It is preferably achieved by a heat-absorbing and heat-generating sheet-like material having a (meth) acrylic polymer carrying acrylate-modified polymer particles having a particle diameter of 5 μm or less. In addition, the notation of (meth) acrylic type means both or one of acrylic type and methacrylic type. Hereinafter, the present invention will be described in detail.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the present inventor examined the fact that a fabric or the like made of moisture-absorbing and heat-generating fibers was poor in stiffness and tension and the rate of moisture absorption was slow. In the case of the loss of elastic modulus and in the case of fiber, the moisture is expressed by the diffusion movement of moisture in the radial direction of the fiber, so the diffusion rate inside the fiber is high even if the saturated moisture absorption capacity is high. It has been found that the rate is limited and the overall moisture absorption rate is slow. However, since there is a limit to the diameter of the fiber, the idea of making the fiber into fine particles was obtained.

Further, the present invention has led to the problem of handling of the particles and the support of the particles on a material having a sufficient waist / tension feeling as a solution to the problem of the waist / tension feeling of the fabric or the like. Things. First, the sheet-like material in the present invention means a material in a thin two-dimensional planar form, such as cloth, paper, knitted fabric, nonwoven fabric, and sheet.

[0008] These sheet-like materials are formed into a two-dimensional form by combining fibrous materials as constituents by various methods, but the fibrous materials used in the present invention are not limited at all. Any shape is acceptable. Therefore, examples of the fibrous material in the present invention include fibrous materials made of organic-inorganic polymers and glass metals, and include, for example, general-purpose nylon, ester, polyvinyl alcohol, acrylic, polyethylene, polypropylene, and natural and regenerated / semi-synthetic materials. Cellulose type, rayon, pulp, kenaf, carbon fiber, glass fiber, steel fiber and the like. Among them, fibrous materials having an ionic group exhibiting hydrophilicity are preferred because they can easily carry polymer particles described below. Such examples include cellulosic rayon, pulp, acrylic and nylon.

Next, the polymer particles will be described. The polymer particles must first have a crosslinked structure.
The polymer itself is acrylic and / or methacrylic (hereinafter referred to as (meth) acrylic), and the cross-linking structure of the polymer is, for example, a difunctional or higher cross-linkable monomer such as divinylbenzene or methylenebisacrylamide. It may be introduced by copolymerization or by introducing a (meth) acrylic polymer by post-treatment with a chemical such as a diamine compound such as hydrazine or an aldehyde such as formalin.

The amount of the crosslinked structure in the polymer varies depending on the type of crosslink and is difficult to be uniquely defined. As a result, the acrylate-modified polymer particles having a salt type carboxyl group have a water absorption of 0%. It is preferably in the order of 0.5 to 5 g-water / g-particles. The water absorption is 1 g of absolutely dry particles at 25 ° C.
Needless to say, it is the amount (g) of water absorbed to equilibrium. If the water absorption is less than 0.5, it is difficult to secure a sufficient amount of the salt-type carboxyl groups described below in the polymer particles, and if it exceeds 5, the contact feeling when absorbing moisture of the sheet material of the present invention becomes unpleasant. And the durability of the particles tends to be poor.

Next, the polymer particles used in the present invention are:
It must have a salt-type carboxyl group of １２12 meq / g, preferably 6-10 meq / g. The amount of the group is one of the factors that strongly influences the heat generation and moisture absorption of the sheet material of the present invention. When the amount is less than 5 meq / g, sufficient heat absorption and heat generation cannot be obtained. However, in order to design such a polymer, the degree of cross-linking is inevitably low, resulting in stickiness of the particles due to moisture absorption or swelling, and migration of water molecules due to swelling. It is not practical because it is suppressed, the moisture absorption performance is reduced, and the particle form cannot be maintained. The term "moisture absorption and heat generation" as used herein refers to the rate of moisture absorption and the amount of saturation, and the rate and total amount of heat generation.

Although the carboxyl group must be in the form of a salt, the “salt” form is an expression corresponding to the H (carboxylic acid) form, and examples of the salt form include Na, K, Li, etc. A class of metal salts may optionally be employed. Further, these metal species are not limited to one kind, and a plurality of kinds may be used in combination. Of course, the fact that all of the carboxyl groups present are salt forms is rare in terms of pH or practical safety. If the amount of the salt carboxyl groups described above is satisfied, the remaining carboxyl groups take H form. Needless to say.

[0013] The polymer particles must have an average particle size of 5 µm or less, more preferably 1 µm or less. It is difficult to limit the lower limit of the average particle size. The reason is that the object of the invention can be achieved no matter how small the particles are, and the actual particle size is determined by the method for producing the acrylate-modified polymer particles used in the practice of the present invention and the method for producing the same. This is because the method depends on the method of supporting the polymer particles on the sheet material.

That is, when polymer particles are produced by polymerization of a (meth) acrylic monomer, extremely fine particles having a diameter of, for example, 0.01 μm may be dispersed in a dispersion medium depending on the polymerization method. Can be obtained in a state,
In the case where this is once dried as a particle powder and then carried on a sheet-like material, a particle having a diameter of 0.01 μm cannot be obtained, and a large particle in which primary particles are agglomerated secondary and tertiary. Will be. On the other hand, in the case of carrying the particles in the dispersed state, the particle diameter in the dispersion medium is maintained as it is. For these reasons, if the lower limit of the average particle diameter is to be determined with a strong force, the minimum value obtained by polymerization is about 0.01 μm.

The upper limit of the particle size is 5 μm as described above,
More preferably, it is 1 μm or less. When the average particle diameter exceeds the upper limit, the distance between the surface of the particles and the core increases, and the inhibition on the rate of moisture absorption and heat generation is the same as in the moisture-absorbing heat-generating fiber described at the beginning of the embodiment of the invention. It becomes so strong that the object of the invention is not achieved.

As described above, the polymer particles used in the present invention are (meth) acrylic polymers obtained by modifying acrylate. First, the (meth) acrylic polymer means an acrylic or methacrylic monomer alone or a copolymer with another copolymerizable monomer.
Examples of (meth) acrylic monomers include methyl,
Ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, hexadecyl, stearyl, 2-ethylhexyl,
Alkyl (meth) acrylates such as cyclohexyl; 2
-Hydroxyethyl, 2-hydroxypropyl, 4-hydroxybutyl, dimethylaminoethyl, 2-methoxyethyl, 3-methoxybutyl, 2-butoxyethyl, ethoxydiethylene glycol, methoxytriethylene glycol, methoxydipropylene glycol, phenoxyethyl, phenoxy Monofunctional (meth) acrylic acid such as diethylene glycol, nonylferoxyethyl, 2-hydroxy-3-phenoxypropyl, monohydroxyethyl succinate, monohydroxyethyl phthalate, tetrahydrofurfuryl, isobornyl, dicyclopentenyloxyethyl, and glycidyl Ester; 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) a Relate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth)
Polyfunctional (meth) acrylic acid such as acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tridipropylene glycol di (meth) acrylate, polydipropylene glycol di (meth) acrylate, and hydroxypivalonic acid Esters: unsaturated nitriles such as acrylonitrile, methacrylonitrile and vinylidene cyanide are exemplified.

Other copolymerizable monomers copolymerizable with these (meth) acrylic monomers include, for example, vinyl halides such as vinyl chloride, vinyl bromide, vinyl fluoride, and vinylidene chloride; and vinylidene halides; Unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid and salts thereof; unsaturated ketones such as methyl vinyl ketone, phenyl vinyl ketone, methyl isobutenyl ketone and methyl isopropenyl ketone;
Vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate and vinyl benzoate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; acrylamide and its alkyl-substituted products; vinyl sulfonic acid, allyl sulfonic acid, and methallyl sulfone Acid, unsaturated sulfonic acid such as styrene sulfonic acid and salts thereof; styrene such as styrene, methyl styrene and chlorostyrene and alkyl or halogen substituted products thereof; allyl alcohol and esters or ethers thereof; vinyl pyridine, vinyl imidazole, dimethyl Basic vinyl compounds such as aminoethyl methacrylate;
Unsaturated aldehydes such as acrolein and methacrylolein; glycidyl methacrylate, N-methylol acrylamide, hydroxyethyl methacrylate, triallyl isocyanurate, divinylbenzene, ethylene glycol di (meth) acrylate, and methylene bisacrylamide. As described above, the crosslinkable monomer used when introducing a crosslinked structure by copolymerization falls within the category of this copolymerizable monomer.

The homopolymerization of these (meth) acrylic monomers or the copolymerization with other copolymerizable monomers is not particularly limited, and suspension polymerization, emulsion polymerization, precipitation polymerization, dispersion polymerization, bulk polymerization which are usually employed are not particularly limited. And the like. A polymerization initiator or a chain transfer agent may be appropriately employed. still,
The point to be noted is the blending ratio of the monomers when the polymer particles of the present invention are produced by copolymerization, and the copolymer from the (meth) acrylic monomer and the other copolymerizable monomer is an acrylate described below. Modification is to have enough acrylate-modified groups to provide the required amount of salt-type carboxyl groups described above.

In the present invention, the (meth) acrylic polymer is acrylate-modified. Here, it is acrylate-modified, but literally in the form of acrylate, as described and understood so far. That is, in the case of an acrylic polymer, for example, the nitrile group of the acrylonitrile-based (co) polymer becomes a salt-type carboxyl group by some treatment, and the acrylonitrile portion, which was a unit monomer of the polymer, becomes an acrylate. Is a methacrylic polymer, for example, a methyl methacrylate (co) polymer of -C
This means that the OOCH3 group becomes a salt-type carboxyl group by some treatment, and the methyl methacrylate portion, which was a unit monomer of the polymer, is still a methacrylate.

In other words, in preparing the polymer particles used in the present invention, it is necessary to introduce a necessary amount of salt-type carboxyl group by a treatment such as hydrolysis of the raw material (meth) acrylic polymer. Speaking of coalescence, it means to be acrylated, that is, to be acrylate-modified. Thus, the sheet-like material of the present invention supports polymer particles having specific conditions.

The method of supporting the polymer particles on the surface of the fibrous material depends on the state of the polymer particles subjected to the supporting step,
For example, whether it is in the form of a dry powder, whether it is an aqueous or organic solvent-based dispersion liquid, or the state of a fibrous material, such as the degree of intimacy with water or the physical roughness of the surface of the material, and There are various combinations of secondary transition points, softening temperatures, etc. Broadly speaking, bonding using other binders, chemical bonding between the functional groups of the particles and the functional groups of the fibrous material, or chemical bonding using a crosslinkable compound,
Utilizing the self-adhesive force of the particles themselves without using a binder,
Some use the interaction between the particles and the fibrous material side, and others use the thermal (softening) property of the fibrous material side.

Accordingly, as a form of carrying, there are adhesion, electrostatic adhesion, chemical affinity, physical mechanical adhesion, and the like. In general, adhesion through a binder has excellent resistance to falling off of particles, but tends to hinder some of the heat generation by moisture absorption, and vice versa when no binder is used. Utilizing the thermal properties of fibrous materials, that is, the method that can be used when polyethylene or the like that softens at a relatively low temperature is adopted, the versatility is poor, but polyethylene is highly hydrophobic and it is difficult to support particles. It is a useful method. On the other hand, if the fibrous material has high hydrophilicity, for example, paper or rayon whose main component is pulp, which is a typical example, has a high affinity for polymer particles having a large amount of carboxyl groups. A large amount can be supported without the need for a binder.

The amount of the specific polymer particles to be supported
No limitation is allowed. The sheet material of the invention is used
Required in certain fields, especially hygroscopic and exothermic
Can be selected as appropriate according to the level of
As the number of binders increases, the more
The tactile sensation, texture, or texture of the material changes significantly.
You. In consideration of this, the amount to be supported is determined.
g / m²~ 500g / m ²Where the neighborhood is commonly used
is there.

Thus, the sheet-like material in which the specific polymer particles are carried on the surface of the fibrous material has a heat-absorbing and heat-generating property. This heat-absorbing heat generation property largely depends on the specific polymer particles absorbing moisture and the heat of condensation of the phase change in which the moisture is condensed. , And the rate and total amount of heat generation are all large. More specifically, in terms of the specific polymer particles employed in the present invention (as described above, the amount supported as a sheet-like material may vary over a wide range, and the amount per sheet-like material may vary slightly. 30-20 wt% at 20 ° C. and 65% RH, and 200
It is about 1000 cal / g. Approximate values of heat absorption and heat generation of the sheet material can be calculated from these values and the amount carried by the sheet material. However, if the binder is used to support the polymer particles as described above, the value tends to decrease. It is.

The speed is 10.5 cm in length supporting 20 g / m ^{2 of} the specific polymer particles used in the present invention,
When a sheet of 15 cm in width is folded in two and dried in an absolutely dry state, the sheet is transferred to a 9.5 liter closed container of 92% RH at 25 ° C. in which a saturated aqueous solution of ammonium dihydrogen phosphate is placed. The decrease in the atmospheric humidity inside the sheet is 50% RH within 5 minutes, and the heat generation is about 6 ° C. to 10 ° C. Hygroscopicity and heat generation as an accurate sheet material
Since it is necessary to consider that it depends on the combination of the polymer particles and the fibrous material, it is better to actually measure with a moisture sensor or a heat sensor.

Having described the sheet-like material of the present invention, a method for producing such a material will be described briefly. First, a (meth) acrylic polymer as a raw material of acrylate-modified polymer particles is prepared. For this, a monomer or a monomer mixture necessary to give a (meth) acrylic polymer is prepared, and a polymerization operation is performed using an appropriate polymerization initiator. A means of suspension polymerization or emulsion polymerization, which is usually aqueous and uses an inorganic initiator or an inorganic redox initiator, is preferable from the viewpoint of environment and cost. The particle size of the produced polymer can be obtained within a desired range by stirring the polymerization system and controlling the concentration of the initiator, the concentration of the emulsifier, the dispersant, and the concentration of the inorganic salt.

In the polymer thus obtained, a cross-linking structure is introduced when the cross-linking monomer is not copolymerized, or a polymer having a cross-linking structure already copolymerized with the cross-linking monomer is used. A process for applying acrylate modification is performed. At that time, there are cases where the polymer dispersion liquid is used as it is or the polymer once separated from the dispersion medium is used for the processing, but it is generally noted that the latter means tends to be accompanied by an increase in the polymer particle diameter due to aggregation. Cost.

The introduction of the crosslinked structure can be carried out by reacting a raw material (meth) acrylic polymer with, for example, a hydrazine compound or an aldehyde. The degree of cross-linking can be controlled by evaluating the degree of action of the cross-linking treatment and the degree of water absorption of the acrylate-modified polymer, in accordance with the degree of acrylate modification. This acrylate modification treatment can be generally performed by a hydrolysis treatment using a mineral acid or an alkali substance, though it depends on the constituent monomers of the (meth) acrylic polymer.

In this case, in the present invention, it is necessary to control the amount of the generated carboxyl group. However, it is necessary to select an appropriate processing condition from the relationship between the processing condition and the measured value of the carboxyl group of the obtained polymer to be processed. Is easy. In the case of hydrolysis treatment, the concentration of acid or alkali at the time of treatment and the temperature and time of the system to be treated are control factors. In the present invention, since a predetermined amount of a “salt type” carboxyl group is required, in the case of a hydrolysis treatment using an acid, it is needless to say that the pH is adjusted with an alkali. Thus, polymer particles satisfying specific conditions can be obtained.

Next, the above-mentioned polymer particles are supported on a sheet material. As described above, the sheet material to be supported may be a two-dimensional planar material made of a fibrous material,
The sheet-like material itself can be subjected to a supporting treatment regardless of various methods for producing the sheet-like material. The simplest support treatment is, for example, immersing the nonwoven fabric, which is the treated sheet material, in an aqueous dispersion or emulsion of the polymer particles or spraying or impregnating the nonwoven fabric with the liquid, and loading the desired amount of polymer particles. In such a case, the pressure may be appropriately adjusted by pressing, centrifugal dehydration, or the like. Of course, a binder may be used in combination for the purpose of promoting the loading or strengthening the binding.

In the case where a binder is used in combination, the chemical affinity between the polymer particles and the sheet-like material to be treated is poor, especially the separation between water and the affinity is large, and the durability of the support is often insufficient. In such a case, the selection of the binder is to mediate one of the highly hydrophilic polymer particles and the other of the fibrous materials constituting the hydrophobic sheet-like material, so that the hydrophilic or hydrophobic properties can be reduced. For example, thermosetting resin such as urea resin, melamine resin, phenol resin, epoxy resin, etc., thermoplastic resin such as polyvinyl acetate, polyvinyl chloride, polystyrene, nylon, acrylic polymer, natural rubber, chloroprene rubber, nitrile rubber, S
BR, rubber-based resins such as urethane rubber, starch, dextrin, glue, soybean glue, arabic gum, natural polymer-based resins such as lacquer can be used. Or solvent dispersion type such as water dispersion type; one-part thermosetting type, moisture-curing type, anaerobic curing type, air-curing type, microcapsule type, etc., and two-part catalyst type, addition reaction type, crosslinking reaction type And the like, and a chemical reaction type such as, for example, and a hot-melt type.

The sheet-like material provided with the required amount of polymer particles as described above is subjected to drying or heat treatment, if necessary, to ensure the loading of the particles. In the above example, the treatment of the polymer particles in an aqueous system has been described. However, in some cases, an organic solvent system can be employed, and in a special case, the polymer particles can be applied as a dry powder. However, in the case of an organic solvent system or a dry powder, it is generally necessary to pay attention to the fact that the polymer particles are likely to aggregate.

In the above, an example of supporting polymer particles on a material already formed on a sheet material has been described. However, it is of course possible to employ a means in which the polymer material is carried on the fibrous material itself, and then the sheet material is formed.
This method is particularly advantageous when the fibrous material is a highly hydrophilic material such as pulp or rayon.
In such a case, for example, in a wet papermaking method using pulp as a main component, a means for papermaking in which a water emulsion or an aqueous dispersion of polymer particles coexists in the system is recommended.

[0034]

The present invention will be further described with reference to the following examples. Parts and percentages in the examples are on a weight basis unless otherwise noted. First, the amount of salt-type carboxyl groups (meq / g) of the moisture-absorbing heat-generating fiber or polymer particles was determined by the following method. 1 g of a sufficiently dried test sample is precisely weighed (X
g), 200 ml of water was added thereto, and while heating to 50 ° C., a 1N aqueous hydrochloric acid solution was added to adjust the pH to 2, and then a titration curve was obtained with a 0.1N aqueous sodium hydroxide solution according to a conventional method. From the titration curve, the consumption amount (Yml) of the aqueous solution of caustic soda consumed by the carboxyl group was determined, and the amount of the carboxyl group was calculated by the following equation. (Amount of carboxyl group meq / g) = 0.1Y / X

Separately, a titration curve was similarly obtained without adjusting the pH to 2 by adding a 1N aqueous hydrochloric acid solution during the above-mentioned operation of measuring the amount of carboxyl groups, and the amount of carboxylic acid was obtained. From these results, the amount of salt-type carboxyl groups was calculated by the following equation. (Salt type carboxyl group amount meq / g) = (carboxyl group amount) − (carboxylic acid amount)

The moisture absorption rate, saturated moisture absorption, heat generation rate, and total heat generation employed in the evaluation of the sheet material of the present invention are based on the following methods. Regarding the waist / tension feeling of the sheet-like material, the results of sensory evaluation by five panelists were as follows: 〇: waist / tension feeling, 張 り: waist / tension feeling,
X: Each mark means no waist / tension.

The heat generation rate and the moisture absorption rate are 10.5 c
A sheet material supporting polymer particles having a width of 15 cm and having a width of 15 cm is folded in two, and dried in an absolutely dry state. A sealed 9.5 liter solution of 92% RH at 25 ° C. in an aqueous solution of saturated ammonium dihydrogen phosphate is placed. Transfer into containers. At this time, a temperature / humidity sensor is inserted between the two-fold sheet samples, and changes with time in temperature and humidity are measured. A curve of the measurement result is drawn, and a slope of a tangent line at 30 seconds after the start of the measurement is obtained on the curve, and a heat generation rate is calculated and displayed in ° C / min. The moisture absorption rate was represented by the degree of decrease in relative humidity at 30 seconds after the start of the measurement, that is, the difference from the original atmospheric humidity of 92% RH (△% RH). Therefore, the larger these values, the higher the heat generation rate and the moisture absorption rate.

The saturated moisture absorption is obtained by leaving a sample of the sheet material at 20 ° C. and 65% RH for 16 hours or more, and precisely weighing (I). Next, the sample is dried at 105 ° C. for 1 hour, and precisely weighed (II) when absolutely dried. Using the obtained value, the saturated moisture absorption is determined from the following equation. (Saturated moisture absorption g / m ² ) = (I−II) / measurement sheet area The saturated moisture absorption corresponding to the saturated moisture absorption of the moisture-absorbing and desorbing fiber raw cotton and polymer particles is the measurement sample of raw cotton and particles. Is determined under the same conditions as above, and I and II are determined by the following equation. (Saturated moisture absorption% by weight) = (I−II) / II × 100

The total calorific value was measured using a twin conduction calorimeter (SET, France).
The measurement was performed using a C-80 calorimeter (manufactured by ARAM). A sample vessel, such as a sheet material, polymer particles, or fibers, which is precisely weighed, is filled into a sample vessel, and the relative humidity is set at 8%.
Nitrogen gas at 0.5% RH was flowed at a flow rate of about 100 ml / min, and the calorific value per sample weight (cal / g) was calculated from the integrated value of the temperature difference-time curve of the conduction calorimeter.

A. Manufacture of moisture-absorbing and exothermic fibers 90% acrylonitrile and methyl acrylate
Acrylic polymer (30 ° C.) consisting of 10%
Intrinsic viscosity in dimethylformamide ([η]: 1.
2) A spinning stock solution obtained by dissolving 10 parts in 90 parts of a 48% rodin soda aqueous solution was spun and stretched (total draw ratio: 10 times) according to a conventional method, and then dried and wet under an atmosphere of 120 ° C / 60 ° C. (Process shrinkage 14%) to obtain a raw material fiber having a single fiber fineness of 2.22 dtex.

A 6.4% hydrazine aqueous solution, 1
Introduction of a crosslinked structure by hydrazine treatment at 02 ° C for 5 hours, 10% aqueous NaOH solution, 90 ° C for 2 hours NaOH
Dehydration after acrylate modification by treatment, washing with water
Drying was performed. When this fiber was evaluated, the water absorption was 2 g.
The fibers were crosslinked to the extent that they did not dissolve in dimethylformamide with -water / g-fibers, and the acrylate-modified fibers of a 15 µm fiber diameter acrylic polymer having 6.0 meq / g of salt-type carboxyl groups. The fiber strength is 0.6 cN
/ Dtex is slightly weak. The moisture absorption and heat generation of the fiber alone is
The saturated moisture absorption was 41%, and the calorific value was 345 cal / g.

B. Production of Acrylate-Modified Polymer Particles 450 parts of acrylonitrile, 50 parts of methyl acrylate and 1181 parts of water were charged in a 2-liter autoclave, and di-tert-butyl peroxide was added as a polymerization initiator in an amount of 0. After addition of 5% by weight, the mixture was sealed, and then polymerized at 120 ° C. for 30 minutes under stirring. After completion of the reaction, the mixture was cooled to about 90 ° C. while stirring was continued, so that the average particle size was 1.0%.
A μm acrylic polymer particle dispersion was obtained.

60 parts by weight based on 100 parts of the obtained polymer particles
The hydrazine was mixed with the parts described in Table 1 and 850 parts of water, and hydrazine treatment was performed at 90 ° C. and at the reaction time shown in Table 1 to introduce crosslinks. Was added, and the mixture was reacted at 120 ° C. for 2 hours to hydrolyze the residual nitrile group to introduce a salt-type carboxyl group (a sodium-type at the end of the hydrolysis reaction). The obtained polymer was dispersed in water, washed and, if necessary, crushed with a bead mill having an average diameter of 1 mm to control the particle diameter. 1
To 5 were prepared. Table 1 shows the evaluation results of the polymer particles in the dispersion.

[0044]

[Table 1]

C. Production of Acrylate-Modified Polymer Particles In place of 450 parts of acrylonitrile and 50 parts of methyl acrylate in the above B, 485 parts of acrylonitrile and p
-Except that it is 15 parts of sodium styrenesulfonate,
In the same manner as described above, the polymer particles Nos. 6 and 7 were obtained. The average particle size of the acrylic polymer particles before the crosslinking treatment was 0.1 μm.

Examples 1 to 4 and Comparative Examples 1 to 4 As a sheet material, a basis weight of 100 g / m ² and a thickness of 2.5 m were obtained when the mixing ratio of polyester and rayon was 70/30.
m, a nonwoven fabric a having a weight of 80 g / m ² , and a thickness of 2.
A 0 mm nonwoven fabric b was prepared by a needle punch method according to a conventional method. The nonwoven fabric was cut into 10.5 cm × 15 cm test pieces, each of which was obtained by B and C, and the polymer particles of particles Nos. 1 to 7 were 10% pure, and an acrylic resin emulsion (AR) or urethane was used as a binder. A resin-like sheet carrying polymer particles was immersed in an aqueous dispersion of polymer particles containing 10% of a resin emulsion (UR), squeezed so that the applied amount of polymer particles became 20 g / m ^2, and dried. A non-woven fabric was obtained as a material. Table 2 shows the evaluation results.

[0047]

[Table 2]

In the first embodiment, particles having an average particle diameter of 2.5 μm are used to determine whether or not the particles have fallen off (by bending the sheet and then flipping the sheet with a finger) to visually observe whether the particles have fallen off. ), And it was confirmed that the sheet had excellent moisture absorption rate and heat generation rate. On the other hand, in Comparative Examples 1 and 2, both the moisture absorption rate and the heat generation rate were inferior. As the particle size increases,
As you can see from their reduced properties,
It is considered that such a result was obtained because the time required for diffusion of water into the inside of the particles became longer. In Comparative Examples 1 and 2 having a large particle diameter, particles were also found to fall off the sheet, and particularly in Comparative Example 2, the particles were so violent that they were not at a level sufficient for practical use.

In Comparative Example 3, the particles No. No. 4, the particles have an extremely low degree of crosslinking, as can be seen from the fact that some of the particles had a water absorption of 30 g-water / g-particles. In this case, the amount of the salt type carboxyl group is 13 meq.
/ G, the saturated moisture absorption is low due to swelling and the like. As a result, the values of moisture absorption, heat generation, saturation, and total amount are all low. Also in Comparative Example 3, the particles were remarkably dropped, and were not practically usable. It is considered that the reason for this is that the particles swelled too much when absorbing water, so that the particles shrank too much due to drying after carrying the particles, and cracks were formed and film formation was not successful.

On the other hand, in Comparative Example 4, the particle No. 5 is used. In this case, although there was no problem of the particles falling off, the amount of salt-type carboxyl groups of the particles themselves was excessively small, and as a result, the moisture absorption characteristics and the heat generation characteristics were extremely low and not at a practical level.

In Examples 2 to 4, the polymer particles before and after the acrylate modification were used in an emulsion state without being subjected to bead mill pulverization. In the case of this method, since the particle diameter is submicron which is smaller by one order than that of Example 1, as a result, a good finish (roughness,
Drop off, texture, uniformity of carrying, etc.). Also in the moisture absorption and heat generation characteristics, Example 2 and Example 4 are the most excellent in speed. One of the reasons is that the particle diameter is small.

In the third embodiment, a nonwoven fabric using a polyester / polyolefin having high hydrophobicity as a fibrous material is used as a base fabric. However, the speed, the saturation, and the total amount were good and practical.

In Example 2, in order to evaluate the repetition characteristics, after measuring the moisture absorption and heat generation characteristics,
After absolute drying at 105 ° C. for 30 minutes, the temperature was returned to room temperature in a desiccator, and then the moisture absorption characteristics and the heat generation characteristics were evaluated again by the above methods. Then, this repetition operation was repeated ten times. Even at the tenth time, the moisture absorption rate, the saturated moisture absorption,
In both the heat generation rate and the total heat generation, 95% or more of the performance obtained in the first test was confirmed, and no significant performance deterioration was observed. From this result, it was confirmed that the sheet of the present invention was excellent in the stability of repetition.

Comparative Example 5 A nonwoven fabric having a basis weight of 100 g / m ^{2 was} prepared using 20 parts of the moisture-absorbing heat-generating fiber described in A and 60 parts and 20 parts of polyester and acrylic, respectively (nonwoven fabric c). This is equivalent to supporting the acrylate-modified polymer particles on the nonwoven fabric in an amount of 20 g / m ² in terms of the amount of the heat-absorbing and heat-generating substance. When this nonwoven fabric was evaluated in the same manner as the nonwoven fabric that previously supported the particles, the texture was evaluated as x for all five panelists, and there was a significant difference between the saturated amount and the total amount in both the hygroscopicity and the heat generation. Although not possible, they were significantly inferior in their respective speeds. This reflects the fact that the moisture-absorbing and heat-generating fiber is reduced in terms of the high elongation, and that the fiber has an obstacle to the speed due to its larger diameter than the particle. Table 2 shows the evaluation results.

[0055]

The sheet-like material of the present invention is characterized by its heat-absorbing and heat-generating properties, and in particular, its speed is high. This is because the polymer particles carried by the sheet-like material are fine, and are hardly reachable from fibers that are themselves capable of absorbing and generating heat. Further, since the sheet-like material carries polymer particles capable of absorbing and generating moisture on the surface of the constituent fibrous material, the skeleton itself of the sheet-like material does not significantly affect mechanically. Therefore, for example, even a sheet-like material such as a non-woven fabric can be provided with a material having a strong waist and tension. Waist
This is also a special effect as compared with a nonwoven fabric or the like using a moisture-absorbing heat-generating fiber with poor tension.

The sheet-like material of the present invention having such characteristics is applied to applications requiring high-speed moisture absorption and heat generation, and supports people's comfortable lives. The fields in which the sheet-like material of the present invention is used include clothes such as inner garments and outer garments, bedding, interiors and the like, batting, filling, etc., shoes and tatami insoles and rugs, chair covering cloths and leather. Examples include cloth, paper, wallpaper, and lining of furniture and containers.

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Claims (1)

[Claims] 1. A (meth) acrylic material having a crosslinked structure and a salt-type carboxyl group of 5 to 12 meq / g on the surface of a fibrous material constituting a sheet material, and having an average particle diameter of 5 μm or less. A heat-absorbing and heat-generating sheet material in which a polymer supports acrylate-modified polymer particles.