JP2017095832A - Humidity conditioning material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a humidity conditioning material having excellent water absorption properties.SOLUTION: A composite fiber is employed that has an ethylene-vinyl ester copolymer saponified product (A) and a water-soluble resin (B), wherein, the fiber surface forms a sea-island structure in which the ethylene-vinyl ester copolymer saponified product (A) is a sea component and the water-soluble resin (B) is an island component.SELECTED DRAWING: None

Description

  The present invention relates to a humidity control material using a composite fiber, and in particular, to a humidity control material using a composite fiber in which a poorly water-soluble resin and a water-soluble resin have a sea-island structure on the fiber surface of the composite fiber. Is.

  The saponified ethylene-vinyl ester copolymer system (hereinafter referred to as “EVOH”) is hydrophilic and has moisture absorption and desorption properties. Therefore, fibers made of EVOH and fibers having EVOH on the surface are used as cooling sensation fibers. It is used.

  For example, in Patent Document 1, EVOH is used as a sea component, and a specific water-soluble thermoplastic polyvinyl alcohol (hereinafter, polyvinyl alcohol is referred to as “PVA”) copolymer is used as an island component. A composite fiber having a mold structure is disclosed. Furthermore, it is disclosed that by dissolving and removing island components with water, forming fine voids and increasing the surface area, a composite fiber having a high moisture absorption amount and excellent cooling feeling can be obtained.

JP 2010-189829 A

However, the composite fiber described in Patent Document 1 has a sea-island structure in the fiber cross section, and the island component exists as a streak on the fiber surface, and the island component of the composite fiber is dissolved and removed with water. Even when the fine voids are formed to increase the surface area, it has been found that there is room for further improvement in terms of water absorption characteristics when used as a humidity control material.
Then, this invention is providing the humidity control material excellent in the water absorption characteristic in such a background.

  However, as a result of intensive studies to solve the above-mentioned problems, the present inventor gave a sea-island structure in which EVOH is a sea component and PVA is an island component on the fiber surface during melt spinning, and water absorption characteristics are good. As a result, the present invention has been completed.

  That is, the present invention comprises a composite fiber containing EVOH (A) and a water-soluble resin (B), and the EVOH (A) is a sea component and the water-soluble resin (B) is an island component on the fiber surface. A humidity control material comprising a composite fiber having a sea-island structure is defined as a first gist.

Further, in the present invention, the logarithmic ratio (B / A) of the melt viscosity at a shear rate of 912 sec ⁻¹ and 210 ° C. of the EVOH (A) and the water-soluble resin (B) is 1.10 to 1.50. The humidity control material is the second gist.

  Furthermore, the present invention provides a humidity control material in which the water-soluble resin (B) is a PVA resin having a 1,2-diol structural unit represented by the following general formula (1). In particular, a humidity control material in which the average degree of polymerization of the PVA-based resin is 600 to 1500 is a fourth summary.

〔式中、Ｒ¹、Ｒ²およびＲ³はそれぞれ独立して水素原子または有機基を示し、Ｘは単結合または結合鎖を示し、Ｒ⁴、Ｒ⁵およびＲ⁶はそれぞれ独立して水素原子または有機基を示す。〕

[Wherein R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic group, X represents a single bond or a bond chain, and R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom. Or an organic group is shown. ]

  Furthermore, the present invention is a humidity control material in which the content ratio (weight ratio, A / B) of EVOH (A) and water-soluble resin (B) is 95/5 to 65/35, among them. This is the fifth gist.

  In addition, in the composite fiber having a fine sea-island structure described in Patent Document 1, since the viscosity of EVOH and a specific PVA resin is substantially equal, the surface of the fiber obtained by melt spinning is the same as that at the time of spinning. The island component (PVA-based resin) is stretched in a streak shape along the spinning direction by the shearing force, and the sea-island structure on the fiber surface as in the present invention cannot be obtained. Is different.

The humidity control material of the present invention is a combination of EVOH (A) and water-soluble resin (B), and by controlling the melt viscosity of both, EVOH (A) is a sea component on the fiber surface during melt spinning. By forming a sea-island structure in which the water-soluble resin (B) is an island component, high water absorption characteristics are exhibited.

  This is presumed that the island component having a high moisture absorption property is not a streak but a point dispersed on the fiber surface, thereby increasing the surface area of the island component and exhibiting a high water absorption property.

  Furthermore, in the present invention, in particular, the water-soluble resin (B) is composed of a composite fiber that is a specific PVA resin having a 1,2-diol structural unit represented by the general formula (1). The wet material has a sea-island structure in which EVOH (A) is a sea component and water-soluble resin (B) is an island component, particularly on the fiber surface. Therefore, it is preferable because it exhibits high water absorption characteristics in an environment having a certain humidity or higher.

  Among the specific PVA resins, in particular, a humidity control material composed of a composite fiber having an average polymerization degree of 600 to 1500 has a relatively high viscosity of the PVA resin, and on the fiber surface, Since the island component composed of PVA resin, which is the water-soluble resin (B), is dispersed in a granular form with respect to the sea component composed of EVOH (A), the surface area of the water-soluble resin (B) is greatly increased. It is preferable because it can increase and exhibit even higher water absorption characteristics.

  Furthermore, in the present invention, in particular, a humidity control material comprising a composite fiber having a content ratio (weight ratio) A / B of EVOH (A) and water-soluble resin (B) of 95/5 to 65/35 is as follows. Both of the required dispersibility and water absorption properties exhibit particularly excellent performance, which is preferable.

It is an enlarged photograph by the scanning electron microscope (SEM) after the melt | dissolution process of Example 1 goods.

The humidity control material using the conjugate fiber of the present invention contains EVOH (A) and a water-soluble resin (B).
In the present invention, the logarithmic ratio (B / A) of the melt viscosity at 210 ° C. at a shear rate of 912 sec ⁻¹ between the EVOH (A) and the water-soluble resin (B) is 1.10 to 1.50. Yes, the EVOH (A) and the water-soluble resin (B) have a sea-island structure in which the EVOH (A) is a sea component and the water-soluble resin (B) is an island component at least on the fiber surface. This is the biggest feature. The preferable range of the logarithmic ratio (B / A) of the melt viscosity is 1.15 to 1.40, particularly 1.15 to 1.30. If the logarithmic ratio (B / A) of the melt viscosity is too large, melt spinning tends to be difficult, whereas if it is too small, a sea-island structure tends to be hardly formed on the fiber surface.

The melt viscosity in the present invention is obtained by measuring the melt viscosity of EVOH (A) and the melt viscosity of the water-soluble resin (B) at 210 ° C. using a capillograph at a shear rate of 912 sec ⁻¹ . Then, the logarithmic ratio (B / A) of the melt viscosity is obtained by dividing the logarithm of the viscosity of the water-soluble resin (B) by the logarithm of the viscosity of EVOH (A).

Hereinafter, the humidity control material using the conjugate fiber of the present invention will be described in order.
First, EVOH (A) will be described.

EVOH (A) is usually a resin obtained by copolymerization of ethylene and a vinyl ester monomer and then saponification, and is a water-insoluble thermoplastic resin. As the polymerization method, any known polymerization method such as solution polymerization, suspension polymerization, and emulsion polymerization can be used. In general, solution polymerization using methanol as a solvent is used. Saponification of the obtained ethylene-vinyl ester copolymer can also be performed by a known method.
That is, EVOH (A) mainly contains an ethylene structural unit and a vinyl alcohol structural unit, and includes a slight amount of vinyl ester structural unit remaining without being saponified.

  As the vinyl ester monomer, vinyl acetate is typically used from the viewpoint of market availability and good impurity treatment efficiency during production. In addition, aliphatic vinyl esters such as vinyl formate, vinyl propionate, vinyl valerate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate, benzoic acid, etc. Examples thereof include aromatic vinyl esters such as vinyl, and are usually aliphatic vinyl esters having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and particularly preferably 4 to 7 carbon atoms. These are usually used alone, but a plurality of them may be used simultaneously as necessary.

  EVOH (A) used in the present invention is an ethylene content measured based on ISO14663 and is usually 20 to 60 mol%, particularly preferably 25 to 50 mol%, more preferably 28 to 45 mol%. preferable. When there is too much ethylene content, compatibility with water-soluble resin (B) mentioned later falls, and there exists a tendency for thread breakage to occur frequently at the time of composite spinning. On the other hand, if the ethylene content is too low, the melting point becomes high, so that it tends to be thermally deteriorated during melt spinning.

  EVOH (A) has an MFR (melt flow rate) of usually 3 to 50 g / 10 minutes (210 ° C., 2160 g), particularly preferably 5 to 40 g / 10 minutes (210 ° C., 2160 g), and more preferably 8 to 20 g / 10 minutes (210 ° C., 2160 g) is preferred. If the MFR is too large, the tension during melt spinning is weak and stable melt spinning tends to be difficult. If it is too small, the melt viscosity is too high and fibers having a small fiber diameter tend to be unable to be spun.

  EVOH (A) has a saponification degree (measured according to JIS K6726. However, EVOH resin is a solution uniformly dissolved in a water / methanol solution), usually 90 mol% or more, preferably 95 mol% or more. Especially preferably, it is 99 mol% or more. When the degree of saponification is too low, there is a tendency that a strange odor is generated due to thermal deterioration during melt spinning, or the fibers are easily colored.

Further, EVOH (A) in the present invention may further contain structural units derived from the comonomer shown below within a range not inhibiting the effects of the present invention (for example, 10 mol% or less).
The comonomer includes olefins such as propylene, 1-butene and isobutene, 3-buten-1-ol, 3-butene-1,2-diol, 4-penten-1-ol, 5-hexene-1,2- Hydroxyl group-containing α-olefins such as diols, derivatives such as esterified products, acylated products, acrylic acid, methacrylic acid, crotonic acid, (anhydrous) phthalic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, etc. Saturated acids or salts thereof, mono- or dialkyl esters having 1 to 18 carbon atoms, acrylamide, N-alkyl acrylamides having 1 to 18 carbon atoms, N, N-dimethylacrylamide, 2-acrylamidopropanesulfonic acid or salts thereof, acrylamidopropyl Acrylamides such as dimethylamine or its acid salts or quaternary salts , Methacrylamide, N-alkylmethacrylamide having 1 to 18 carbon atoms, N, N-dimethylmethacrylamide, 2-methacrylamideamidopropanesulfonic acid or its salt, methacrylamideamidopropylamine or its acid salt or its quaternary salt, etc. Methacrylamides, N-vinylpyrrolidone, N-vinylformamide, N-vinylamides such as N-vinylacetamide, vinyl cyanides such as acrylonitrile and methacrylonitrile, alkyl vinyl ethers having 1 to 18 carbon atoms, hydroxyalkyl vinyl ethers Vinyl ethers such as alkoxyalkyl vinyl ethers, vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, vinyl bromide, vinyl sila such as trimethoxyvinyl silane Allyl halides such as allyl acetate, allyl chloride, allyl alcohol such as allyl alcohol, dimethoxyallyl alcohol, trimethyl- (3-acrylamido-3-dimethylpropyl) -ammonium chloride, acrylamido-2-methylpropane And comonomers such as sulfonic acid.

Furthermore, “post-modified” EVOH such as urethanization, acetalization, cyanoethylation, oxyalkylenation and the like can also be used.
In particular, EVOH obtained by copolymerizing a hydroxy group-containing α-olefin is preferable from the viewpoint of good secondary moldability, and EVOH having a 1,2-diol structure in the side chain is particularly preferable.

  In the EVOH (A) used in the present invention, a compounding agent generally blended with EVOH, for example, a heat stabilizer, an antioxidant, an antistatic agent, a colorant, an ultraviolet ray absorbing agent, as long as the effects of the present invention are not impaired. Agent, lubricant, plasticizer, light stabilizer, surfactant, antibacterial agent, drying agent, antiblocking agent, flame retardant, crosslinking agent, curing agent, foaming agent, crystal nucleating agent, antifogging agent, biodegradation additive , A silane coupling agent, an oxygen absorbent and the like may be contained.

  Examples of the water-soluble resin (B) used in the present invention include starch, cellulose, polyvinyl pyrrolidone, polyethylene glycol, PVA resin, water-soluble nylon, and polyacrylamide. Among these, a PVA resin is preferable because of its excellent compatibility with EVOH. Furthermore, a PVA resin having a 1,2-diol structural unit in the side chain, particularly 1 represented by the following general formula (1): A PVA resin having a 2-diol structural unit is preferable because of its excellent hot melt moldability.

〔式中、Ｒ¹、Ｒ²およびＲ³はそれぞれ独立して水素原子または有機基を示し、Ｘは単結合または結合鎖を示し、Ｒ⁴、Ｒ⁵およびＲ⁶はそれぞれ独立して水素原子または有機基を示す。〕

[Wherein R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic group, X represents a single bond or a bond chain, and R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom. Or an organic group is shown. ]

In addition, it is desirable that R ^{1 to} R ³ and R ^{4 to} R ⁶ in the 1,2-diol structural unit represented by the general formula (1) are all hydrogen atoms, and the following general formula (1 ′) A PVA-based resin having the structural unit represented is preferably used.

In addition, R ^{1 to} R ³ and R ^{4 to} R ⁶ in the 1,2-diol structural unit represented by the general formula (1) are organic groups as long as they do not significantly impair the resin characteristics. The organic group is not particularly limited. For example, the organic group has 1 to 4 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, and tert-butyl group. Alkyl groups are preferred, and these alkyl groups may have a substituent such as a halogen group, a hydroxyl group, an ester group, a carboxylic acid group, or a sulfonic acid group, if necessary.

Furthermore, X in the 1,2-diol structural unit represented by the general formula (1) is most preferably a single bond because it easily forms a sea-island structure with the aforementioned EVOH (A). A binding chain may be used as long as the effect of the present invention is not impaired. Examples of the bonding chain include hydrocarbon groups such as alkylene, alkenylene, alkynylene, phenylene, and naphthylene (these hydrocarbon groups may have halogen such as fluorine, chlorine, and bromine), and the like. _{O -, - (CH 2 O} ) m -, - (OCH 2) -, - (CH 2 O) mCH 2 -, - CO -, - COCO -, - CO (CH 2) mCO -, - CO (C ₆ H ₄ ) CO—, —S—, —CS—, —SO—, —SO ₂ —, —NR—, —CONR—, —NRCO—, —CSNR—, —NRCS—, —NRNR—, —HPO _{4 -, - Si (OR)} 2 -, - OSi (OR) 2 -, - OSi (OR) 2 O -, - Ti (OR) 2 -, - OTi (OR) 2 -, - OTi (OR) 2 O-, -Al (OR)-, -OAl (OR)-, -OAl (OR) O-, etc. (R represents each Any substituents and standing, a hydrogen atom, an alkyl group is preferred, m is a natural number) and the like. Of these, an alkylene group having 6 or less carbon atoms, particularly a methylene group, or —CH ₂ OCH ₂ — is preferable from the viewpoint of stability during production or use.

  Examples of the method for producing the PVA resin include (i) a method of saponifying a copolymer of a vinyl ester monomer and a compound represented by the following general formula (2), and (ii) a vinyl ester monomer and A method of saponifying and decarboxylating a copolymer with a compound represented by the following general formula (3), or (iii) a copolymer of a vinyl ester monomer and a compound represented by the following general formula (4) The method of forming and deketalizing is preferably used. Of these, the method (i) is particularly preferable. In addition, about the method of (i), (ii), and (iii), the method demonstrated by Unexamined-Japanese-Patent No. 2006-95825 is employable, for example.

In the general formulas (2), (3) and (4), R ¹ , R ² , R ³ , X, R ⁴ , R ⁵ and R ⁶ are all the same as in the general formula (1). It is. R ₇ and R ₈ are each independently a hydrogen atom or R ⁹ —CO— (wherein R ⁹ is an alkyl group). R ¹⁰ and R ¹¹ are each independently a hydrogen atom or an organic group similar to R ^{1 to} R ⁶ .

Among these, in the general formula (2), R ^{1 to} R ⁶ are hydrogen, X is a single bond, and R ^{7 to} R ⁸ are R ^{9 in} terms of excellent copolymerization reactivity and industrial handleability. 3,4-diasiloxy-1-butene in which —CO— and R ⁹ is an alkyl group is preferable, and in particular, 3,4-diacetoxy-1-butene in which R ⁹ is a methyl group is preferable. Used.

Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, versatic. Examples of vinyl acetate include vinyl acetate and vinyl trifluoroacetate. Among these, vinyl acetate is preferably used from an economical viewpoint.

  In addition to the above-mentioned monomers [vinyl ester monomers, compounds represented by the general formulas (2), (3), (4)], as long as the physical properties of the resin are not significantly affected, the copolymerization component Α-olefins such as ethylene and propylene; hydroxy group-containing α-olefins such as 3-buten-1-ol, 4-penten-1-ol, 5-hexene-1,2-diol, and acylated products thereof Derivatives such as: Itaconic acid, maleic acid, acrylic acid and other unsaturated acids or their salts or mono- or dialkyl esters; Acrylonitrile and other nitriles; Methacrylamide, diacetone acrylamide and other amides; Ethylene sulfonic acid, allyl sulfonic acid , Methallylsulfonic acid, AMPS (2-acrylamido-2-methylpropanesulfonic acid), etc. A compound such as olefin sulfonic acid or a salt thereof may be copolymerized.

  The PVA resin suitably used in the present invention is usually 0.1 to 20 mol%, preferably 1 to 15 mol%, more preferably 1,2-diol structural unit represented by the general formula (1). Contains 3 to 10 mol%. Even if the molar fraction of the 1,2-diol structural unit represented by the general formula (1) is excessively increased, improvement in melt spinnability and hygroscopicity has reached its peak, and a PVA resin having a predetermined polymerization degree is obtained. There is a tendency to become difficult to be. On the other hand, if the molar fraction is too low, the melting point becomes high, so the molding temperature must be increased, and melt spinnability tends to decrease, or insoluble matter tends to be generated due to thermal degradation. Moreover, there exists a tendency for the hygroscopic property of PVA-type resin to fall.

  In the PVA resin, the content (molar fraction) of the 1,2-diol structural unit represented by the general formula (1) is the 1H-NMR spectrum (solvent) of the completely saponified PVA resin. : DMSO-d6, internal standard: tetramethylsilane), specifically, hydroxyl proton, methine proton, and methylene proton in 1,2-diol unit, methylene proton in main chain, linked to main chain It can be calculated from the peak area derived from protons and the like of the hydroxyl group.

  Furthermore, the saponification degree (measured in accordance with JIS K6726) of the PVA resin is usually 70 to 100 mol%, particularly 75 to 99.9 mol%, and more preferably 80 to 99.5 mol%. In particular, the PVA resin used in the present invention is controlled in crystal size by the 1,2-diol structure of the side chain even if the degree of saponification is high, and the rise in melting point is suppressed, and good melt moldability is obtained. There are few problems of thermal degradation. If the degree of saponification is too low, the thermal stability during melt spinning tends to be reduced, or an acetic acid odor tends to occur.

  The average degree of polymerization (measured in accordance with JIS K6726) of the PVA-based resin is usually 600 to 1500, particularly 800 to 1400, and more preferably 1000 to 1300. If the average degree of polymerization is too high, the melt viscosity becomes high and spinning tends to be difficult. On the other hand, if the average degree of polymerization is too low, the PVA resin easily flows along the spinning direction without resistance during kneading with EVOH (A) and during melt spinning, and EVOH (A) is a sea component, water-soluble component on the fiber surface. There is a tendency that a sea-island structure in which the PVA-based resin that is the conductive resin (B) is an island component is difficult to be formed.

  The MFR (melt flow rate) of the PVA resin is usually 0.05 to 6 g / 10 minutes (230 ° C., 2160 g), and particularly preferably 0.05 to 4 g / 10 minutes (230 ° C., 2160 g). Furthermore, 0.08 to 2 g / 10 min (230 ° C., 2160 g) is preferable. If the MFR is too large, the tension during melt spinning is weak and stable melt spinning tends to be difficult. If it is too small, the melt viscosity is too high and spinning tends to be difficult.

  You may mix | blend an additive with the water-soluble resin (B) used by this invention as needed. For example, polyhydric alcohols such as glycerin, sorbitol, and polyethylene glycol, or alkylenes thereof as plasticizers for improving melt fluidity, suppressing thermal decomposition in the fiberizing process, and obtaining good plasticity and spinnability An oxide adduct can be blended. Furthermore, you may mix | blend lubricants and antioxidants, such as ethylene bisstearyl amide.

  In the present invention, a composite fiber can be produced by mixing and spinning the EVOH (A) and the water-soluble resin (B). In the mixed spinning, for example, EVOH (A) and water-soluble resin (B) can be melt-kneaded with one extruder, and subsequently discharged from the same spinning nozzle to be wound up and fiberized. Alternatively, EVOH (A) and water-soluble resin (B) and melt-kneaded with one extruder, pelletized, charged into a spinning machine, discharged from the nozzle of the spinning machine, wound up, and fiberized May be. The production conditions such as the temperature of the spinneret during spinning and the shear rate when passing through the nozzles depend on the EVOH (A) and water-soluble resin (B) content ratio of the composite fiber to be produced, the cross-sectional shape of the composite fiber, etc. Set as appropriate.

In the present invention, the greatest feature is that the EVOH (A) is a composite fiber having a sea-island structure where the EVOH (A) is a sea component and the water-soluble resin (B) is an island component on the fiber surface. In order to achieve such a sea-island structure, the logarithmic ratio (B / A) of the melt viscosity at 210 ° C. at a shear rate of 912 sec ⁻¹ between the EVOH (A) and the water-soluble resin (B) is 1.10-1. 50 is preferable.

In order to satisfy the logarithmic ratio (B / A) of the melt viscosity at 210 ° C. at a shear rate of 912 sec ⁻¹ between the EVOH (A) and the water-soluble resin (B), for example, the following method is appropriately used. It becomes possible by combining.

<Method of adjusting the melt viscosity of EVOH (A)>
(1) The polymerization degree, ethylene composition, and saponification degree are adjusted in the reaction step.
(2) Two or more types of EVOH having different degrees of polymerization, ethylene composition and saponification are melt blended to adjust the apparent melt viscosity.
(3) Adjust using a small amount of an additive that has a large effect on the melt viscosity. Examples of such additives include (1) polyamide resins that are reactive resins with respect to EVOH resins, and (2) polyolefins, polyesters, polystyrenes, and polycarbonates that are non-reactive resins with respect to EVOH resins. Examples thereof include polymers, (3) inorganic substances such as fillers and glass fibers, and (4) higher fatty acid metal salts such as higher fatty acid zinc salts. The higher fatty acid salt used in the higher fatty acid zinc salt refers to a fatty acid having 8 or more carbon atoms (preferably 12 to 30 carbon atoms, more preferably 12 to 20 carbon atoms). Specifically, lauric acid, tridecylic acid, Examples include myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, oleic acid, capric acid, behenic acid, linoleic acid, and the like. Among these, stearic acid, oleic acid, and lauric acid are preferably used.

<Method for adjusting melt viscosity of water-soluble resin (B)>
(1) In the production process, the degree of polymerization (or molecular weight) is adjusted.
In particular, in the case of a PVA resin, there is a method of adjusting not only the degree of polymerization but also the degree of saponification and the degree of modification.
(2) Two or more types of water-soluble resins having different degrees of polymerization are melt blended to adjust the apparent degree of polymerization.
(3) Adjust using a small amount of an additive that has a large effect on the melt viscosity. Examples of such additives include (1) inorganic substances such as fillers and glass fibers, (2) acid anhydrides, isocyanate-based crosslinking agents, amine-based crosslinking agents, aldehyde-based crosslinking agents, epoxy-based crosslinking agents, and melamine-based crosslinking agents. And crosslinking agents such as metal chelate crosslinking agents. Among them, boric acid, methylol melamine, ferric chloride, titanium lactate, titanium diisopropoxybis (triethanolaminate), zirconium carbonate ammonium salt, zirconium oxychloride, etc. can be used as a crosslinking agent for PVA resin. . (3) Plasticizers such as polyhydric alcohols such as glycerin, sorbitol and polyethylene glycol, or alkylene oxide adducts thereof can also be used.

  In particular, among these, by using the water-soluble resin (B) whose degree of polymerization is adjusted by melt blending in the reaction step or the subsequent step, the log ratio (B / A) of the target melt viscosity is within a predetermined range. It is preferable to do.

  The content ratio (A / B) of the EVOH (A) and the water-soluble resin (B) is preferably 95/5 to 65/35 by weight, and preferably 90/10 to 75. / 25. If the EVOH (A) is too much relative to the water-soluble resin (B), a sea-island structure in which the EVOH (A) is a sea component and the water-soluble resin (B) is an island component cannot be sufficiently obtained on the fiber surface, and moisture absorption There is a risk that the characteristics will deteriorate. Conversely, if EVOH (A) is too small relative to the water-soluble resin (B), the water-soluble resin swells or dissolves when it absorbs moisture, and the fiber shape tends not to be maintained.

  In addition, the cross-sectional shape of the composite fiber of the present invention may be any shape such as a perfect circle shape, a hollow shape, and a modified cross-sectional shape, but when using this composite fiber as a humidity control material, The larger the contact area, the higher the hygroscopic capacity on the surface, so that the atypical cross-sectional shape is preferable. However, if the efficiency of the manufacturing process is considered, it may be a perfect circle.

  In addition, the composite fiber in the present invention may contain other thermoplastic resins together with the essential components EVOH (A) and the water-soluble resin (B). Other thermoplastic resins include, for example, polypropylene resins, polyethylene resins (LLDPE, LDPE, VLDPE, etc.), polyester resins (PET, PBT, etc.), polyamide resins (nylon 6, nylon 6/66, nylon 12). In particular, polyester resins are preferable in terms of improving fiber properties such as strength.

  When such other thermoplastic resins are included, it is necessary that the portion made of the composite resin containing EVOH (A) and the water-soluble resin (B) is exposed to the fiber surface. . For example, in a side-by-side type or core-sheath type composite fiber, another thermoplastic resin is arranged inside the fiber, and a composite resin containing EVOH (A) and a water-soluble resin (B) is arranged outside the fiber. It is important to make it.

  In the present invention, the spun yarn spun using the above-described composite fiber is also conceptually included in the composite fiber of the present invention. As such spun yarn, spun yarn using a short fiber composed of a composite fiber having a sea-island structure in which EVOH (A) is a sea component and water-soluble resin (B) is an island component, or the short fiber and other short fibers are used. Examples include spun yarn made of fibers. Examples of the other short fibers include the above-described other thermoplastic resins (polyester resins, polyamide resins, etc.) and short fibers made of natural fibers (cotton, hemp, silk, etc.).

  The spun or spun composite fiber may be stretched or heat-treated as necessary. The heat treatment can be performed simultaneously with stretching or in a separate process from stretching. In addition, when using this composite fiber as a humidity control material, in order to suppress shrinkage that occurs when the composite fiber absorbs or releases moisture, the composite fiber itself may be preliminarily heat-treated to the extent that thermal contraction is involved.

  The composite fiber according to the present invention has a sea-island structure in which EVOH (A) is a sea component and water-soluble resin (B) is an island component on at least the fiber surface, and the water-soluble resin (B ) Can be obtained in a granular and dispersed state, and this composite fiber is used as a humidity control material.

  Therefore, when this composite fiber is used as a heat insulating material for a building or mixed with a wall covering material or paint for a building, it exhibits a high hygroscopic property due to the characteristics of the water-soluble resin dispersed in the fiber, and has an excellent control. It can be used as a wet material. That is, it is possible to keep the humidity of the surrounding environment within a certain range by absorbing the surrounding moisture well under high humidity and releasing the absorbed moisture when the humidity becomes low.

And when using as a heat-insulating material, a wall covering material, and a humidity control member of a paint as mentioned above, although it is easier to handle as a short fiber, it can also be used as a long fiber.
In the humidity control material comprising the composite fiber of the present invention, the fineness of the composite fiber is 0.01 to 3000 dtex, preferably 0.5 to 300 dtex, from the viewpoint of obtaining a humidity adjustment effect. About the length of a long fiber, length can be freely adjusted according to a use.

  Examples of the present invention will be specifically described below together with comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the following description, “%” and “parts” mean a weight basis.

〔material〕
Details of the materials used in Example 1 and Comparative Examples 1 and 2 are shown below.
EVOH1:
Ethylene content 29 mol%, MFR 8 g / 10 min (2160 g, 210 ° C.), saponification degree 99.7 mol%
Water-soluble resin 1 (modified PVA1 having a 1,2-diol structural unit in the side chain):
Content of 1,2-diol structural unit 6 mol%, polymerization degree 1200, MFR 0.1 g / 10 min (2160 g, 230 ° C.), saponification degree 99 mol%

[Method for producing water-soluble resin 1 (modified PVA1)]
To a reaction vessel equipped with a reflux condenser, a dropping funnel and a stirrer, 1000 parts of vinyl acetate, 120 parts of methanol, 87.6 parts of 3,4-diacetoxy-1-butene (73% of the total charge, 6 mol% Charged vinyl acetate) and 0.07 mol% of azobisisobutyronitrile (vs. charged vinyl acetate) were added, and the temperature was raised under a nitrogen stream while stirring to initiate polymerization. Further, 32.4 parts of 3,4-diacetoxy-1-butene (27% of the total charged amount) was added dropwise at a constant rate over 7 hours. When the polymerization rate of vinyl acetate reached 72%, m-dinitrobenzene was added as a polymerization inhibitor to complete the polymerization. Subsequently, unreacted vinyl acetate monomer was removed from the system by a method of blowing methanol vapor to obtain a methanol solution of PVA resin.

  Next, the solution was diluted with methanol and adjusted to a concentration of 45% and charged into a kneader. While maintaining the solution temperature at 35 ° C., a 2% methanol solution of sodium hydroxide was added to the vinyl acetate structural unit in the PVA resin and Saponification was carried out by adding at a ratio of 12 mmol to 1 mol of the total amount of 3,4-diacetoxy-1-butene structural units. As the saponification proceeds, the saponified product is precipitated and separated into solids and liquids, washed well with methanol, dried in a hot air dryer at 70 ° C. for 12 hours, and modified PVA resin A water-soluble resin 1 was obtained.

  The saponification degree of the obtained water-soluble resin 1 was 99 mol% when analyzed by the alkali consumption required for hydrolysis of residual vinyl acetate and residual 3,4-diacetoxy-1-butene. The degree was 1200 when analyzed according to JIS K6726. The amount of the side chain introduced containing the 1,2-diol structure was 6 mol% when calculated by measurement with a 1H-NMR spectrum (solvent: DMSO-d6, internal standard: tetramethylsilane).

[Example 1]
EVOH1 / water-soluble resin is prepared by charging EVOH1 pellets and water-soluble resin 1 powder at a mass ratio of 80/20 into a twin-screw extruder (TEX30α manufactured by Nippon Steel Works) by separate feed, and melt-kneading with the following temperature pattern. An alloy pellet of Resin 1 was obtained.
<Temperature pattern>
C2: 90 ° C, C3: 180 ° C, C4: 200 ° C
C5 to C16: 230 ° C., D: 230 ° C.

  By subjecting the obtained alloy pellets to melt spinning, a target composite fiber (80 μm) was obtained.

[Comparative Example 1]
EVOH fibers were produced in the same manner as in Example 1 using only EVOH1 pellets.

[Reference Example 1]
The composite fiber of Example 1 was immersed in hot water at 80 ° C. for 3 hours and then vacuum dried at 40 ° C. overnight to obtain a porous fiber from which the water-soluble resin as an island component was eluted and removed. The porosity of the obtained porous fiber was 20 vol%.

  In Example 1 and Reference Example 1, the melt viscosity ratio between the resin materials to be combined before melt spinning the composite fiber was determined according to the following method. Moreover, in order to confirm the state of the sea-island structure on the fiber surface, in Example 1 above, the state of the fiber surface was observed and sensory evaluated according to the following method.

[Melting viscosity ratio]
The melt viscosity of each resin at a shear rate of 912 (sec ⁻¹ ) and 210 ° C. was measured using a capillograph (manufactured by Toyo Seiki Seisakusho, 1B PMD-C). And the value which remove | divided the logarithm of the viscosity of water-soluble resin by the logarithm of the viscosity of EVOH1 was made into melt viscosity ratio. The larger this value, the greater the difference in viscosity between the two.

[Observation of fiber surface]
The fiber (80 μm) of Example 1 was immersed in warm water at 60 ° C., subjected to ultrasonic treatment for 3 hours to dissolve the water-soluble resin on the fiber surface, and then dried. Then, the surface of the treated fiber was observed with SEM (manufactured by JEOL Ltd., JSM-6060LA). FIG. 1 is an enlarged photograph (magnification: 1000 times) of Example 1 by the SEM.

[Measurement of water absorption]
After measuring the weight (W2) after standing for 1 week in an atmosphere of 40 ° C. and 90% RH, the sample was dried at 105 ° C. for 3 hours to obtain the absolute dry weight (W1). And the amount of water absorption (g / cm3) was computed by following Formula.
(Calculation formulas of Example 1 and Comparative Example 1)
Water absorption (g / cm3) = (W2-W1) / (W1 / resin density)
(Calculation formula of Reference Example 1)
Water absorption (g / cm3) = (W2−W1) / (W1 / (resin density × 0.8))
Here, the resin density is 1.21 in Example 1 and Reference Example 1, and 1.20 in Comparative Example 1.

From the above results, in Example 1, the water-soluble resin (B) is granular and finely dispersed on the fiber surface, and when such a composite fiber is used as a humidity control material, excellent moisture absorption performance is obtained. You can see that
On the other hand, since the product of Comparative Example 1 is a fiber of EVOH resin alone, the moisture absorption performance is inferior. The product of Reference Example 1 is EVOH porous fiber, and is not a composite fiber having a sea-island structure in which EVOH (A) is a sea component and the water-soluble resin (B) is an island component on the fiber surface. As shown in Document 1, although the water absorption was improved as compared with Comparative Example 1 by making it porous, the water absorption as in Example 1 was not obtained.
In addition, from FIG. 1, since the water-soluble resin of Example 1 product dissolved fine voids on the fiber surface, the water-soluble resin is on the fiber surface. It can be seen that the particles are finely dispersed. That is, the product of Example 1 is considered to have improved water absorption because the water-soluble resin having excellent water absorption is finely dispersed in the form of particles on the fiber surface, so that it easily absorbs surrounding water.

  The present invention can be widely used as a humidity control material having excellent water absorption characteristics.

Claims (5)

  It consists of a composite fiber comprising an ethylene-vinyl ester copolymer saponified product (A) and a water-soluble resin (B), and the ethylene-vinyl ester copolymer saponified product (A) is a sea component on the fiber surface. A humidity control material, wherein the water-soluble resin (B) comprises a composite fiber having a sea-island structure as an island component. The logarithmic ratio (B / A) of the melt viscosity at a shear rate of 912 sec ⁻¹ and 210 ° C. of the saponified ethylene-vinyl ester copolymer (A) and the water-soluble resin (B) is 1.10 to 1.50. The humidity control material according to claim 1, wherein: The humidity control material according to claim 1 or 2, wherein the water-soluble resin (B) is a polyvinyl alcohol resin having a 1,2-diol structural unit represented by the following general formula (1).

[Wherein R ¹ , R ² and R ³ each independently represent a hydrogen atom or an organic group, X represents a single bond or a bond chain, and R ⁴ , R ⁵ and R ⁶ each independently represent a hydrogen atom. Or an organic group is shown. ]   4. The humidity control material according to claim 3, wherein the polyvinyl alcohol resin has an average degree of polymerization of 600 to 1500.   2. The content ratio (weight ratio, A / B) of the saponified ethylene-vinyl ester copolymer (A) and the water-soluble resin (B) is 95/5 to 65/35. The humidity-control material as described in any one of -4.

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