JP2002035037A - Biodegradable hygienic article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a biodegradable hygienic article, the all component of which consist of biodegradable materials. SOLUTION: The biodegradable hygienic article is mainly composed of biodegradable films, nonwoven fabrics, tacky adhesive tapes and water absorptive materials. The water absorptive materials consist of galactomannan, boron ions and tervalent or higher polyvalent metal ions exclusive of the boron ions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a water-absorbing polymer, a water-impermeable film, a non-woven fabric, and an adhesive tape which are suitably used for sanitary materials such as disposable diapers (disposable diapers), sanitary napkins and incontinence pads. The present invention relates to a sanitary article that absorbs and retains urine or blood and has biodegradability.

[0002]

2. Description of the Related Art Disposable hygiene products (paper diapers and sanitary products) using polyacrylic acid-based or polyacrylonitrile-based water-absorbing materials have already been developed since the 1980's, and many manufacturers still prevent leakage, deodorization and breathability. For the purpose of improving the texture, the structure and structure of the structure, the performance of the water absorbing material, and the like have been improved, and a number of patents have been filed. A disposable diaper or sanitary product basically includes an absorbent core 3 made of a water-absorbing material and cellulose fluff between a water-permeable sheet (top sheet 1) and a water-impermeable sheet (backsheet layer 5). At the waist portion or at the base of the thigh, an end trap portion without an absorber is formed, and at the end trap portion, gathers are formed with elastic elastic members interposed, and the disposable diaper is placed around the waist of the wearer or the thigh. It fits around and prevents leakage and displacement. In addition, the acquisition layer aims to prevent urine and loose stool from leaking out due to uneven distribution of urine in the local area and rapid absorption into the water-absorbing material, and to spread urine and loose stool uniformly throughout the absorbent core. And a non-woven fabric having a multi-layer structure called a transport layer 2 between the top sheet 1 and the absorbent core portion 3 or a surge management layer 4 for preventing leakage from the absorbent core portion 3 to the back sheet layer 5. Many are equipped with non-woven fabrics (see FIG. 1). For example, in a disposable diaper for the purpose of preventing leakage of urine and loose stool, JP-A-63-21901,
JP-A-64-30304, JP-A-5-184622, JP-A
62-250201, JP-A-7-308341, JP-A-11-34
JP-A-7063, JP-A-8-73507, JP-A-7-184946 and the like. Also, for the purpose of preventing stuffiness during disposable diapers, for example, the backsheet has been improved such that a film having air permeability while being impermeable has been used, and the purpose of preventing such stuffiness has been made. JP-A-49-144601, JP-A-60-17101, JP-A-7-149937 and the like are disclosed therein.

[0003] In recent years, such disposable diapers and sanitary products have been developed not only for infants but also for adults and indoor pets due to their convenience, and the demand for them has been rapidly increasing. Examples of the water-absorbing material in the absorbent core used for such applications include, for example, a partially neutralized cross-linked polyacrylic acid (JP-A-55-84304, US Pat. No. 462500).
No. 1), a partially hydrolyzed starch-acrylonitrile copolymer (JP-A-46-43995), a starch-acrylic acid graft copolymer (JP-A-51-125468), a vinyl acetate-acrylate ester copolymer. Hydrolyzate of polymer (JP-A-52-14689), 2-acrylamide-
Copolymerized crosslinked product of 2-methylpropanesulfonic acid and acrylic acid (European Patent 0068189), crosslinked product of a cationic monomer (US Pat. No. 4,906,717), crosslinked isobutylene-maleic anhydride copolymer (US Pat. No. 43895)
No. 13) is known.

However, since these synthetic polymer water-absorbing materials do not have biodegradability, disposal after use is a problem. At present, sanitary goods containing these synthetic polymer-based water-absorbing materials are incinerated at the time of disposal and buried in landfills. It has been pointed out that it is a source of gas that causes global warming and acid rain as well as damage to the earth. Furthermore, when incinerating used paper diapers with a high water content, when placed in an incinerator, the combustion temperature inside the furnace will drop sharply, not only to accelerate the deterioration of furnace materials, but also to burn dioxins easily generated Due to the atmosphere, the burden on the exhaust gas treatment equipment at the subsequent stage is increased, and an exhaust gas treatment equipment with higher performance is required. In the landfill method, the plastic has a problem that the volume is bulky, the ground does not stabilize because it does not rot, and a major problem is that there is no longer a place suitable for landfill. That is, these resins are poorly decomposable and exist semipermanently in water and soil, which is a very serious problem in view of environmental conservation in waste treatment.

On the other hand, as a material constituting a back sheet of a disposable diaper or a sanitary article, a film made of polyethylene, polypropylene or polyester has been used because of its excellent water impermeability. As a material constituting a water-permeable layer such as a water-permeable top sheet, an acquisition layer, and a transport layer, a nonwoven fabric made of cellulose, rayon, polyethylene, or the like has been used because of its excellent feel. However, since these components other than cellulose and rayon do not have biodegradability, they will remain in the soil when the waste is landfilled after use. The problem has been raised.

[0006] Under such circumstances, all components (top sheet, back sheet, acquisition layer, transport layer, surge management layer, adhesive sheet, absorbent core) are made of a biodegradable material. The development of disposable diapers and sanitary products was expected.

[Technical background of biodegradable water-absorbing materials, films and nonwoven fabrics] In recent years, biodegradable polymers have attracted attention as "earth-friendly materials".
It has been proposed to use it as a film or nonwoven. Examples of the biodegradable water-absorbing material include polyethylene oxide cross-linked products (JP-A-6-157795, etc.),
Crosslinked polyvinyl alcohol, crosslinked carboxymethylcellulose (US Pat. No. 4,650,716), crosslinked alginic acid, crosslinked starch (JP-A-55-15634), crosslinked polyamino acid (JP-A-7-224163, JP-A-7-309943) JP-A-8-59820, JP-A-8-504219, JP-A-9-169840, etc .;
-59891, JP-B-3-66321, JP-A-56-56
No. -97450).

[0008] Biodegradable water-impermeable films include so-called biodegradable plastics, the main ones of which are polylactic acid-based polymers, starch-polycaprolactone copolymers, succinic ester-based polymers, and poly-degradable plastics. 3-hydroxybutyrate-3-hydroxyvalerate copolymer,
A poly-β-hydroxybutyric acid polymer, a poly-ε-caprolactone polymer, a polybutylene succinate polymer, a polyesteramide polymer and the like are known. As a non-woven fabric having biodegradability, a non-woven fabric made of cellulose and rayon is known. In addition, as a pressure-sensitive adhesive sheet having biodegradability, in addition to the above-mentioned biodegradable plastic as a base material, a film composed of polybutyric acid, a polymer alloy of starch and polyvinyl alcohol, and the like are known. As a pressure-sensitive adhesive, natural rubber is used as a rubber component. As a tackifier, rosin, terpene and derivatives thereof are known.

By the way, when compared with a non-biodegradable synthetic polymer-based water-absorbing material, the above-mentioned biodegradable water-absorbing material is hardly used at present because of low water absorption performance and high cost. And was not used in sanitary products at all. For this reason, despite the fact that a part of a biodegradable sanitary article can be manufactured using a biodegradable plastic or cellulose from a water-impermeable sheet or a nonwoven fabric, the water-absorbing material is non-biodegradable, Sanitary goods had not been put to practical use. JP-A-7-8520 and JP-A-7-132127 use a non-biodegradable starch-acrylic acid graft polymer as a water-absorbing material, and a polylactic acid-based polymer as a water-impermeable film or a water-permeable nonwoven fabric. Patents have been published for the biodegradable disposable diapers and sanitary products used. However, a sanitary product consisting of a biodegradable material other than the water-absorbing material cannot be said to be a `` complete biodegradable sanitary product ''. It is necessary to remove only the absorbent core and separately incinerate. Such time-consuming "partially biodegradable hygiene products" have not been put to practical use because they have no merit for consumers. However, outside of some countries, the absorbent core part of the aforementioned "partially biodegradable sanitary products" was composted without being removed after use, and compost containing polyacrylic acid and polyacrylamide was produced. . However, the safety of these polyacrylamides and polyacrylic acids has not been completely proven, and it has been pointed out that these monomers (acrylic acid and acrylamide) have neurotoxicity, carcinogenicity, and mutagenicity. ing. In other words, there is no guarantee that no unreacted monomer remains in these polymers, and what kind of compounds are converted to what compounds are discarded by ultraviolet rays or microorganisms in the environment. However, it has not been confirmed that compost containing polyacrylic acid or polyacrylamide is safe for plants and animals [Kurane Ryuichiro et al., Functional Materials, 19
Vol., October, 1999, pp. 24-34].

In recent years, components of a disposable sanitary article (such as a sanitary napkin) which has conventionally been composed of a synthetic polymer film or a nonwoven fabric of natural fibers, etc. (a water-permeable sheet layer,
Biodegradable, such as acquisition layer and backsheet layer)
Water-disintegrating or water-disintegrating paper, which is sandwiched with a polyvinyl alcohol film or sheet as an impermeable layer to prevent leakage of urine or blood, is commercially available as a so-called "toilet" sanitary article. However, the water-absorbing polymer used in these water-absorbing portions is a synthetic polymer-based water-absorbing material having no biodegradability, and these must be removed as a precipitate in a sewage treatment plant. When a product composed of such a biodegradable portion (portion composed of cellulose) and a non-biodegradable portion (water-absorbing polymer) is flushed into a toilet, it can be reduced as household waste, but is disposed of at a disposal site. Then, the non-biodegradable water-absorbing polymer deposited as a precipitate must be removed and finally incinerated. As a result, the burden on the facilities of the sewage treatment plant increases, and the problem of generation of DXNs due to incineration and the problem of deterioration of the facilities due to an increase in the load on the incinerator cannot be solved at all, and composting cannot be performed. Furthermore, the water content of the water-absorbing polymer increases when collected as sludge (due to the free swelling of the water-absorbing polymer in the sludge) compared to when collected as sludge. It is considered that the load is several times to several hundred times that of the case of refuse, and as a result, the load on the incinerator is significantly increased.

On the other hand, a biodegradable water-absorbing material obtained by drying a gel obtained by crosslinking galactomannan with a polyvalent metal ion such as a boron ion, a titanium ion, an aluminum ion, or a zirconium ion as described above is already known. U.S. Pat.No. 5,532,350 discloses that, as an example, it has the ability to absorb about 30 to 50 times its own weight of physiological saline by crosslinking with carboxymethylated galactomannan and titanium ions or zirconium ions or both ions, No water-absorbing effect of a water-absorbing material comprising unmodified galactomannan and titanium ions and boron ions is shown. According to this patent, a water-absorbing material composed of carboxymethylated galactomannan and titanium ions has excellent water-absorbing ability for physiological saline but low gel strength. on the other hand,
It is described that a water-absorbing material composed of carboxymethylated galactomannan and zirconium ions has high gel strength but low water-absorbing ability. Therefore, a water-absorbing material having excellent gel strength and water-absorbing ability by cross-linking titanium ions and zirconium ions with carboxylmethylhydroxypropylated galactomannan is disclosed, but the water-absorbing ability is as high as 38 g / g in physiological saline. However, carboxylmethylhydroxypropylated galactomannan is very expensive, and there have been many problems in putting it into practical use as a water-absorbing material for disposable hygiene articles. In U.S. Pat.No. 4,334,461, a water-absorbing material composed of galactomannan and sodium borate is prepared and the physiological saline water-absorbing ability is measured.However, no effect on the water-absorbing material obtained by further crosslinking titanium ions is disclosed. . The inventors also prepared a water-absorbing material composed of galactomannan and boron ions based on the examples and measured the water-absorbing ability.
Although it has 0-70 times, the gel strength is very weak,
Gel leakage occurred from a nonwoven fabric or nylon bag, and was not practical for use as a water-absorbing material for sanitary goods.

Although the polyamino acid-based water-absorbing material has an excellent water-absorbing capacity of 1000 times or more its own weight, it absorbs 40 to 70 times the urine or blood containing electrolytes such as sodium chloride. There is no significant difference from the acrylic acid-based water-absorbing material in terms of performance, but it has not been put to practical use due to the expensive raw materials and processes.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to make all the constituent materials biodegradable, high in safety, and prevent the user from feeling uncomfortable. An object of the present invention is to provide inexpensive sanitary articles (e.g., disposable diapers and sanitary articles) having a natural texture.

[0014]

Means for Solving the Problems As a result of intensive studies, the present inventors have determined that all constituent materials have biodegradability,
Sanitary goods using a specific water-absorbing material have the same or better texture and water absorption performance than sanitary goods composed of conventional non-biodegradable materials. It has been found that the present invention has excellent complete biodegradability, and the present invention has been completed. That is, the present invention is a sanitary article mainly composed of a film, a nonwoven fabric, an adhesive tape, and a water-absorbing material, wherein the film, the nonwoven fabric, the adhesive tape, and the water-absorbing material have biodegradability, and the water-absorbing material is A biodegradable sanitary article characterized by comprising galactomannan, boron ions, and trivalent or higher polyvalent metal ions other than boron ions.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The biodegradable sanitary article of the present invention mainly comprises (a) a water-impermeable film portion, (b) a nonwoven fabric portion,
(C) Absorbing core portion and (d) adhesive sheet portion.

The water-impermeable film of the component (a) is mainly used for the backsheet layer 5 of a sanitary article, and has appropriate flexibility, strength, thermal dimensional stability, transparency, water repellency, A biodegradable plastic film having air permeability and heat resistance is used. Specific examples of the biodegradable plastic used for the film include, for example, aliphatic hydroxycarboxylic acids, aliphatic polyester polymers having a biodegradable property that can be produced by combining an aliphatic dihydric alcohol and an aliphatic dibasic acid Is mentioned.

Specific examples of the aliphatic hydroxycarboxylic acid used in the aliphatic polyester polymer include glycolic acid, lactic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, 6
-Hydroxycaproic acid and the like. Further examples include cyclic esters of aliphatic hydroxycarboxylic acids, for example, lactide which is a dimer of lactic acid, glycolide which is a dimer of glycolic acid, and ε-caprolactone which is a cyclic ester of 6-hydroxycaproic acid. These can be used alone or in combination of two or more.

Specific examples of the aliphatic dihydric alcohol include:
Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,3-butanediol, 1,4-butanediol, 3-methyl-1,5 pentanediol, 1,
6-hexanediol, 1,9-nonanediol, neopentyl glycol, polytetramethylene glycol,
1,4-cyclohexanediol and the like can be mentioned. These can be used alone or in combination of two or more.

Specific examples of the aliphatic dibasic acid include succinic acid, oxalic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid and dodecanedioic acid. No. These aliphatic dibasic acids can be used alone or in combination of two or more.

Examples of other biodegradable plastics include a semi-aliphatic polyester polymer in which terephthalic acid and / or isophthalic acid are partially copolymerized with the aliphatic polyester polymer, and an aliphatic polyester is used as the aliphatic polyester. Examples thereof include a polyesteramide-based polymer, a starch-based polymer, a polyvinyl alcohol-based polymer, and a cellulose acetate-based polymer in which a diamine, an aliphatic aminocarboxylic acid, and a lactam are copolymerized.

Depending on the purpose, these polymers may contain various additives such as an antioxidant, an ultraviolet absorber, a plasticizer, a heat stabilizer, a flame retardant, a release agent, an inorganic additive, a crystal nucleating agent, and an antistatic agent. Inhibitors, pigments and anti-blocking agents can be added.

Among these biodegradable plastics,
From the viewpoint of safety and cost, a polylactic acid-based polymer is preferably used. The polylactic acid-based polymer includes not only polylactic acid (homopolymer) but also a copolymer and a mixture mainly composed of biodegradable polylactic acid. The lactic acid forming the polylactic acid may be any of L-lactic acid, D-lactic acid, DL-lactic acid and a mixture thereof. Further, polylactic acids obtained from these lactic acids may be mixed and used. Further, elongation and elasticity can be adjusted as necessary by copolymerization, mixing of other flexible biodegradable polymers, or mixing of biodegradable plasticizers. As these plasticizers, those which are biodegradable and have excellent compatibility with polylactic acid are suitably used. Examples thereof include a monovalent or polyvalent fatty acid ester-based plasticizer, a monovalent or polyvalent aliphatic alcohol ester-based plasticizer, a polyalkylene glycol-based plasticizer, and an aliphatic polyester-based plasticizer.

A known method may be used to obtain the polylactic acid-based polymer. For example, a method of subjecting lactic acid to dehydration condensation or ring-opening polymerization of a cyclic ester of lactic acid is used. In order to increase the molecular weight, a small amount of a chain extender, for example, a diisocyanate compound, a diepoxy compound or an acid anhydride may be used. The polylactic acid-based polymer preferably has a mass average molecular weight in the range of 10,000 to 1,000,000. If the molecular weight is smaller than this, a film having a tensile strength that can be used practically cannot be obtained. And it becomes difficult to form a film.

The method for obtaining the biodegradable plastic film is not particularly limited, and the film is formed into a film by a known forming method. Examples thereof include a method of forming a film by a T-die molding method, an inflation molding method, a calendar molding method, a hot press molding method, and the like. Further, these films may be stretched in at least one direction. The stretching method is not particularly limited, and examples thereof include a roll stretching method, a tenter method, and an inflation method.

The thickness of the film is not particularly limited as long as it has a suitable strength and flexibility.
Is preferably, and more preferably 10 to 100 μm. It is desirable that films made of these biodegradable plastics have appropriate flexibility and softness from the viewpoint of texture. Such a film preferably has a tensile elongation at break of 100% or more and a tensile modulus of 1000 MPa or less, more preferably 200% or more and 600 MPa or less.

In order to further improve the gas permeability of the biodegradable plastic film, it is possible to add inorganic and organic fillers to the polylactic acid polymer. Inorganic fillers include calcium carbonate, talc, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, aluminum hydroxide, zinc oxide, magnesium hydroxide, calcium oxide, magnesium oxide , Titanium oxide, alumina, mica, zeolite, silicate clay, and the like, and calcium carbonate, talc, clay, silica, diatomaceous earth, titanium, and zeolite are preferable. In addition, examples of the organic filler include cellulose powder such as wood powder and pulp powder. The average particle size of the filler is preferably 30 μm or less, and 10 μm
The following are more preferable, and those having 0.7 to 5 μm are particularly preferable. If the particle size is too large, the denseness of the pores of the film will be poor, and if it is too small, the dispersibility in the resin will be poor. After forming a flat unstretched sheet, the film is made porous by being uniaxially stretched in the longitudinal direction or biaxially stretched in the longitudinal and transverse directions to become a film having air permeability.

The non-woven fabric of the component (b) is mainly used for the top sheet 1, the acquisition layer, the transport layer 2, the surge management layer 4 and the like, which are excellent in liquid permeability of sanitary goods, and has a melt spinnability. It is not particularly limited as long as it is a nonwoven fabric made of biodegradable fibers having good, appropriate flexibility, strength, water permeability, heat resistance, and feel. For example, cellulose, rayon, and the like, polylactic acid-based polymer, starch-polycaprolactone copolymer,
Succinic ester-based polymer, poly 3-hydroxybutyrate-3-hydroxyvalerate copolymer, poly-β-
Non-woven fabrics composed of fibers spun alone or in combination of one or more resin components selected from hydroxybutyric acid-based polymers, poly-ε-caprolactone-based polymers, polybutylene succinate-based polymers, polyesteramide-based polymers, etc. Can be

From the viewpoints of melt spinnability, skin safety, processability, strength, cost and the like, the melting point of the polylactic acid-based polymer is lower than that of the polylactic acid-based polymer by 30 ° C. or more and the melting point is 9%.
A nonwoven fabric made of a fiber obtained by compound-spinning a biodegradable resin having a temperature of 0 ° C. or higher is preferable. Above all, a nonwoven fabric made of a fiber obtained by compound-spinning a polylactic acid-based polymer and a polybutylene succinate-based polymer is more preferable because of its excellent feel upon use (feel) when attached.

For single spinning or composite spinning, spinning may be performed by a known melt spinning method and apparatus, and then stretched by 100% or more, preferably 200% or more, in order to obtain strength. Particularly, examples of the form of the composite spinning include a core-sheath type or a parallel type composite spinning, and a core-sheath type composite spinning is preferable. A core-sheath type composite spun fiber having the unified core component is more preferable. When using a composite spun fiber as the nonwoven fiber, the melting point of the polylactic acid-based polymer component must be at least 30 ° C. higher than the melting point of the biodegradable resin component to be composite spun in order to form a nonwoven fabric and maintain the strength by heat bonding. is necessary. Further, when processing nonwoven fabric, a certain degree of heat resistance is required. Usually, a drying step is required after hydroentanglement. In this case, if the drying temperature is not about 100 ° C., the drying efficiency becomes poor.
0 ° C. or higher is preferred. When the core-sheath composite fiber is used in the present invention, the core-sheath composite ratio of the polylactic acid polymer component and the biodegradable resin component to be composite-spun is 10/90 to 90/1.
0, preferably 30/70 to 70/30.

In the present invention, the monofilament or the core-sheath composite fiber constituting the nonwoven fabric may be either a long fiber or a short fiber, and can be appropriately selected depending on the purpose of use. The fineness, density and basis weight of the non-woven fabric used for the top sheet, acquisition layer, transport layer, surge management layer, etc.
There is no particular limitation as it is appropriately selected depending on the desired liquid permeability, flexibility, and texture such as touch, but the composite staple fiber used when making a nonwoven fabric by a papermaking method has a fineness of 0.5.
-5 dtex is preferable, and 1-3 dt is more preferable.
ex, and the cut length is preferably 1 to 25 mm, more preferably 3 to 15 mm. Fineness is 0.5 dte
When it is smaller than x and the cut length is smaller than 1 mm, papermaking is difficult. When the fineness is larger than 5 dtex and the cut length is longer than 25 mm, it is difficult to obtain a uniform nonwoven fabric by papermaking.

The non-woven fabric used for the top sheet, the acquisition layer and the transport layer preferably has excellent liquid permeability and is not very bulky, and has a density of 0.01 to 1 g / cm.
³ , more preferably 0.05 to 0.2 g / cm ³
It is. The basis weight is preferably from 1 to 50 g / m ^2, more preferably from 5 to 20 g / m ^2. If the basis weight is 50 g / m ² or more, the liquid permeability will be poor. On the other hand, in the surge management layer sandwiched between the absorbent core and the back sheet, it is preferable that the liquid permeability is not so excellent in order to prevent urine and loose stool from leaking to the back sheet, and the basis weight of the nonwoven fabric used varies depending on the fineness, but generally. 20 to 200 g / m ² is preferred.

The absorbent core portion 3 of the component (c) is composed of a water-absorbing material and cellulose fluff, etc., and quickly absorbs and gelates a target liquid in sanitary goods, so that even if pressure is applied, moisture is contained in the gel. Must be held by the Conventionally, non-biodegradable synthetic polymers such as powdered or fibrous polyacrylic acid-based resins have been used as water-absorbing materials, but since they have no biodegradability, they are used as water-absorbing materials in the present invention. Cannot be used.

In the present invention, the water-absorbing material has biodegradability and is composed of galactomannan, boron ions, and trivalent or higher polyvalent metal ions other than boron ions. Examples of trivalent or higher polyvalent metal ions other than boron ions include titanium ions, aluminum ions, niobium ions, antimony ions, zirconium ions, cerium ions, lanthanum ions, yttrium ions, iron ions, and the like. Since there is almost no effect of the above, titanium ions, zirconium ions and cerium ions are preferred. The molecular weight of galactomannan is preferably 10,000 or more, more preferably 50,000 or more. If the molecular weight is 10,000 or less, it is not suitable because no gel is formed even when crosslinked with metal ions.

In the present invention, the water-absorbing material absorbs an aqueous solution of a cation having a valency of at least 40 times its own weight and having a valency of 2 × 10 ^−5.
It is preferable to have a gel strength of N / mm ² or more in order to provide a texture that does not cause the user to feel discomfort such as stickiness or sliminess. In the present invention, the divalent or lower cation aqueous solution is not only an aqueous solution in which only sodium, potassium, calcium, and magnesium are dissolved,
An aqueous solution (including urine, sweat, blood, etc.) in which other organic substances (organic acids, amine substances, proteins, amino acids, fatty acids, alcohols, etc.) are dissolved together with cations having a valency of 2 or less is also included.

In the present invention, the concentration of swelling (solation) of galactomannan in water when a water-absorbing material is prepared is such that galactomannan can uniformly swell in water and the gel is formed when cross-linked with boron ions or titanium ions. The concentration is not particularly limited as long as it can be easily prepared, but is preferably 0.1% by mass to 10% by mass, more preferably 0.5% by mass to 3% by mass.

In the present invention, the cross-linking agent for cross-linking galactomannan is a boron ion or a trivalent or higher polyvalent metal ion other than the boron ion, but does not cause a decrease in biodegradability, water absorption ability and gel strength. Within this range, other crosslinking agents such as aldehyde compounds such as glutaraldehyde and glyoxal, amine compounds such as ethylenediamine and polyamide resin, and 2,2-bishydroxymethylbutanol tri [3- (1-aziridine)] propionic acid Aziridine compounds, isocyanate compounds such as tolylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, polyhydric alcohols such as glycerol, propylene glycol and ethylene glycol, epichlorohydrin, ethylene glycol diglycidyl ether, diethyl It is also possible to use in admixture with an epoxy compound such as glycol diglycidyl ether.

When galactomannan is cross-linked with boron ions or trivalent or higher polyvalent metal ions other than boron ions, if each is used alone, the water absorption is low or the gel strength after water absorption is low. Therefore, it is necessary to share boron ions and trivalent or higher polyvalent metal ions other than boron ions. In this case, the galactomannan sol may be cross-linked using a mixed cross-linking agent solution containing a trivalent or higher polyvalent metal ion other than boron ions and boron ions, or after the galactomannan sol is cross-linked with boron ions,
Subsequently, it may be crosslinked with a trivalent or higher polyvalent metal ion other than boron ion, or after cross-linking the galactomannan sol with a trivalent or higher polyvalent metal ion other than boron ion, and then may be crosslinked with boron ion. , Galactomannan-
Boron ion-trivalent or higher polyvalent metal ion crosslinked gel other than boron ion may be recrosslinked with a trivalent or higher polyvalent metal ion other than boron ion, and further galactomannan-trivalent or higher other than boron ion May be re-crosslinked with a mixed crosslinking agent of boron ions and trivalent or higher polyvalent metal ions other than boron ions.
The method of crosslinking is not particularly limited because it differs depending on the form of the water-absorbing material used, but is preferably a powdery water-absorbing material, and more preferably a fibrous water-absorbing material, a film-like water-absorbing material and a sheet-like water-absorbing body.

The forms of boron ions and trivalent or higher polyvalent metal ions other than boron ions contained in the crosslinking agent include chlorides, sulfates, carbonates, acetates, formates, milk oxides, alkoxide derivatives and the like. However, since the preferred form differs depending on the metal used,
It is necessary to select it appropriately. For example, for titanium,
Chloride or alkoxide is preferred, and for boron, hydrate of alkali metal borate is preferred. Preferred alkali metal borates are sodium borate and potassium borate. Preferred titanium chloride is titanium tetrachloride, and preferred titanium alkoxide derivatives are titanium (IV) diisopropoxide bisacetylacetonate, titanium (IV) triethanolaminate isopropoxide, titanium (IV) tetraisopropoxy , Titanium (IV) di-n-butoxybistriethanolamine, titanium (IV) isopropoxyoctylene glycolate, Tyzor1
31 (Du pont), TyzorGBA (Du pont) and the like.

It has been reported that boron inhibits the activity of urease, an enzyme that decomposes urea, which is a cause of ammonia generated from disposable diapers, especially after use. Therefore, the composition of the water-absorbing material used for disposable diapers has been reported. (US Pat. No. 4,949,672, US Pat. No. 5,176,108).

The concentration of metal ions used for cross-linking galactomannan sol is such that the water absorption is at least 40 times its own weight and the gel strength after water absorption is higher due to the cross-linking of boron ions and trivalent or higher polyvalent metal ions other than boron ions. 2 × 10 ^-5 N / mm
^A range in which a dried product having ^two or more can be prepared is preferable. With respect to boron ions, the amount is preferably 10 to 2,000 mmol / kg of galactomannan, and 50 to 1,000
0 mmol is particularly preferred. The trivalent or higher polyvalent metal ion other than boron ion varies depending on the type and form, but is preferably about 1 to 120 mmol, more preferably 10 to 60 mmol, per kg of galactomannan.

The temperature for forming a crosslinked gel of galactomannan with boron ions and trivalent or higher polyvalent metal ions other than boron ions is not particularly limited, but is preferably 5 to 90 ° C. in order to promote the reaction. 20-50
C is more preferred. At 90 ° C. or higher, the molecular weight is reduced by thermal decomposition of galactomannan, and at 5 ° C. or lower, it does not swell.

The pH of the gel is changed by adding a crosslinking agent. The final pH of the gel is preferably from 5 to 10, more preferably from 6 to 9. Therefore, when the pH is out of this range, the pH of the gel may be adjusted by appropriately adding sodium hydroxide or hydrochloric acid. Particularly, galactomannan is hydrolyzed in the presence of a strong acid to reduce the molecular weight. Therefore, when an acidic crosslinking agent solution is used, it is necessary to adjust the pH simultaneously with or immediately after the addition of the crosslinking agent. When such a cross-linking agent is used, it is preferable to add the galactomannan sol after cooling as much as possible in order to reduce the rate of the hydrolysis reaction. Cooling temperatures range from 1 to 10C. If the molecular weight of galactomannan is reduced, the texture of the gel after water absorption is likely to deteriorate (slip occurs). Therefore, it is desirable to avoid this as much as possible.

In some cases, the gel after crosslinking may be crushed by a blender with a rotary blade or the like, and the surface of the gel particles may be again crosslinked with a crosslinking agent. The crosslinking agent used in this case is preferably the above-mentioned trivalent or higher polyvalent metal ion.

The method for drying the crosslinked gel is not limited to any drying method, as long as the method does not reduce the water absorption capacity after drying and the gel strength after water absorption. For example, room temperature drying, heating drying, freeze drying, drying under reduced pressure,
In addition to methods such as vacuum drying, the water in the gel
Hygroscopic, volatile anhydrous hydrophilic organic solvent such as ~ 5 monohydric alcohols (e.g., methanol, ethanol, isopropanol), ketones having 3-6 carbon atoms (e.g., acetone) or mixtures thereof. After drying, there is a method of drying, but heat drying at 30 to 50 ° C. or freeze drying is preferable.

The shape of the water-absorbing material after drying is not particularly limited, but may be various shapes according to the purpose of use. For example, granules, sheets, powders,
Fragments, flakes, rods, lines, etc. These shapes may be formed after drying, or at the time of drying, the gel may be placed in a forming device having such a shape and dried. The form of the water-absorbing material used for the absorbent core is not particularly limited to powder, fiber, film, and sheet.

The thus obtained water-absorbing material may further contain, if necessary, a deodorant, a fragrance, various inorganic powders, a foaming agent, a pigment, a dye, an antibacterial agent, a hydrophilic short fiber, a plasticizer, an adhesive, and a surfactant. An agent, a fertilizer, an oxidizing agent, a reducing agent, water, salts and the like may be added to impart various functions to the water-absorbing material.
As an inorganic powder, a substance inert to an aqueous liquid or the like,
For example, fine particles of various inorganic compounds, fine particles of clay minerals, and the like can be given.

The mixing ratio of the water-absorbing material constituting the absorbent core and the cellulose fluff is not particularly limited, and may not include the cellulose fluff in some cases. When mixing the cellulose fluff, the mixing ratio is preferably from 5/95 to 95/5, and more preferably from 30/70 to 70/30.

The amount of the water-absorbing material contained in the absorbent core of one sanitary article differs depending on the type of the sanitary article. For example, in the case of a disposable diaper, the amount is preferably 5 to 15 g, more preferably 10 to 12 g. Also, for example, in the case of feminine hygiene products, it is 0.
The amount is preferably 1 to 5 g, more preferably 0.5 to 1.5 g.

The pressure-sensitive adhesive sheet 7 of the component (d) is used to adhere to underwear for attaching sanitary products, or to adhere back and forth of a back sheet at a waist portion so that a disposable diaper is not detached. The pressure-sensitive adhesive sheet is composed of a biodegradable plastic film portion as a substrate and a pressure-sensitive adhesive portion. As the biodegradable film as the substrate, the biodegradable plastic film used in the above (a) is used, and a stretched film of a polylactic acid polymer is preferable in terms of excellent strength. The pressure-sensitive adhesive is not particularly limited as long as it has biodegradability.For example, a rubber component such as natural rubber or isoprene rubber is used as a base material, and a pressure-sensitive adhesive composition to which a natural rosin tackifier is added is used. Can be.
As a method of applying the pressure-sensitive adhesive composition on the substrate, a known coating method, for example, a roll coater method, an immersion method, a brush application method, a spray method and the like can be mentioned. The thickness of the adhesive is preferably from 2 to 200 μm.

In the case of disposable diapers, in order to prevent leakage of urine and loose stool from the crotch and waist, the biodegradation mainly composed of natural rubber is applied to the backsheet and top sheet corresponding to the crotch and waist. It is also possible to equip gathers using elastic stretch materials.

The above components (a) to (d) are bonded and fixed to each other by a known method such as hot melt bonding or heat bonding to manufacture a sanitary article. In some cases, a gather (elastic portion) or the like may be provided around the limb of the disposable diaper with a biodegradable material for the purpose of preventing leakage and improving the mobility of the wearer. The disposable diapers described in this specification include pants-type disposable diapers that are used when disciplining infants for urination and defecation.

[0052]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The properties of the water absorbing material were measured by the following method.

(1) Free water absorption The free water absorption was measured using a 0.9% by mass aqueous sodium chloride solution by the tea bag method. That is, 2
1 g of the water-absorbing material is placed in a 50-mesh nylon tea bag, and the tea bag is immersed in 1 L of a 0.9% by mass aqueous sodium chloride solution for 3 hours.
After draining for a minute, the mass was measured. The amount of water absorbed by the water-absorbing material is defined as the weight of the water-absorbing material before swelling, based on the mass of the tea bag containing the water-absorbing material swollen by absorbing water as a blank, with the mass of the tea bag containing no water-absorbing material soaked in water for 3 hours as a blank. The value obtained by dividing the value obtained by subtracting the mass of the blank and the blank by the mass of the water-absorbing material before swelling was defined as the water absorption (g / g resin). The water absorption rate was determined by dividing the water absorption amount (g / g resin) after 5 minutes by the water absorption amount (g / g resin) after 3 hours by 100 and defining the value as the water absorption rate (%). ,evaluated.

(2) Water Absorption Under Pressure The water absorption under pressure was measured by placing a stainless steel screen on a funnel having a diameter of 80 mm and a 400 mesh nylon screen thereon. 1 g of the water-absorbing material powder was spread evenly on a nylon screen, and further sandwiched between the same nylon screens. 0.7 psi on it
The piston and the weight were placed on the tank, and the saline in the tank was gradually immersed from the lower part of the funnel, and the water level was adjusted until the lower part of the piston was slightly immersed. At this time, the measurement was started, and the amount of physiological saline absorbed 30 minutes after the start of the measurement was measured.
After 30 minutes, the saline in the funnel was removed, and after draining for 10 minutes, the mass of all saline in the tank, tube, and funnel was reduced from the mass of saline before the start of measurement, and water absorption per water-absorbing material was performed. Amount.

(3) Gel strength in free-absorbing state Gel strength in free-absorbing state was measured by stirring the water-absorbing material particles sieved to 500 to 1,000 μm according to the water absorption ratio obtained in advance and stirring. 3% by immersion in
The sample was allowed to freely absorb water for a time, and the viscoelasticity G * was measured at 1 Hz and room temperature using Rheometric SR-5000 manufactured by Scientific Inc., and the value was used as the gel strength.

Example 1 A polymer obtained by increasing the molecular weight of a polybutylene succinate polymer synthesized from 1,4-butanediol having a melting point of 118 ° C. and succinic acid through a urethane bond (Bionole, manufactured by Showa Polymer Co., Ltd.) was used. A sheath component, a polylactic acid polymer having a melting point of 165 ° C. as a core component, using a core-sheath type composite spinning mold in a melt extruder, heating and dissolving the resin component at 210 ° C.
It was extruded from many micropores and spun. The mixing ratio of the core / sheath component was 40/60 for the core component / axial component. The spun filament group was stretched and drawn while being taken up by an ejector with high-speed air, and collected and deposited on a moving wire-made collecting support to form a web. The average fineness of the obtained long fiber filament is 1.5 dtex,
The basis weight was 15 g / m ² and the density was 0.1 g / cm ³ . The biodegradable water-permeable span is introduced by introducing the top of this web between the uneven roll heated to 110 ° C and the smooth roll, and fusing the portion corresponding to the convex part of the uneven roll at a linear pressure of 30 kg / cm. A bonded nonwoven was obtained. Also, using the same method as described above, the average fineness is 1.5 dtex and the basis weight is 60 g / m ^2.
Was obtained.

As a raw material of polylactic acid, (A) a mass average molecular weight of 2 was obtained from the hopper port of a twin-screw kneader having a diameter of φ45 mm.
10,000 polylactic acid polymer (Cargill Dow Polymers,
EcoPLA4030D), 74 parts by mass, and (B) 10 parts by mass of silica (manufactured by Fuji Silysia Ltd., Sylysia) having an average particle diameter of 3 μm as an antiblocking agent, and (c) erucamide (manufactured by NOF CORPORATION, Alflow P1)
0) 1 part by mass was charged while being measured by a mass feeder. As a plasticizer, 15 parts by mass of polyethylene glycol having an average molecular weight of 400 (manufactured by Sanyo Chemical Co., Ltd., Sunfine DM400), both ends of which were methoxy-blocked, were quantitatively injected from the middle of the cylinder by a liquid metering pump. After melt-kneading (A) to (D) under the condition of a temperature of 180 ° C. to 190 ° C., the composition extruded into strands was cooled in a water bath and cut into pellets. The polylactic acid composition pellets thus obtained were dried at 40 ° C. under reduced pressure for 8 hours. The dried pellets were collected at a temperature of 1 using a single screw extruder having a diameter of 50 mm.
It was melted at 80 ° C., extruded from a T-die into a sheet, and quenched with a casting roll to obtain an unstretched sheet having a thickness of 25 m. 220% of the film thus obtained
The tensile modulus of the stretched film was determined according to JIS K6732.
It was 550 Mpa when measured according to.

A biodegradable film having a thickness of 200 μm was obtained by the same method as described above, and a pressure-sensitive adhesive composition containing a natural rubber as a base material and a natural rosin tackifier was added to one surface of the film. To give a biodegradable pressure-sensitive adhesive sheet.

4 g of guar gum (PF-20, manufactured by Dainippon Pharmaceutical Co., Ltd.)
Was added to 200 ml of pure water (solid content concentration: 2% by mass) heated to 50 ° C. with stirring to dissolve and swell to prepare a sol solution. After swelling for 1 hour, Tyz was added to 200 ml of the sol.
or131 solution with a final titanium content of 60 mmol / kg guar gum mass and 0.5 M aqueous sodium tetraborate decahydrate with a final boron ion content of 5
The mixture was added so as to be 00 mmol each, and sufficiently crosslinked while being crushed and mixed by a blender. The pH of these gels was adjusted to 9.0 ± 0.1. This gel is freeze-dried, and the obtained dried product is crushed to 1 mm or less with a file under a stream of nitrogen, and the obtained fragments are subjected to water absorption under free pressure, water absorption under pressure, water absorption rate, and gel strength (gel viscoelasticity).
G *) was measured. As a result, the water-absorbing material of this embodiment is:
The free water absorption of physiological saline was 51 g / g, and the gel strength was 3.87 × 10 ⁻⁴ N / mm ² . Further, no gel leakage from the nylon bag was observed at all, and the gel after water absorption was all present in the form of particles, and no adhesiveness was observed between the particles. The water absorption rate was 64%. The water absorption under pressure of 0.7 psi was 25 g / g.

A mixing ratio of the water-absorbing material and the cellulose fluff was set to 20/80 to prepare a biodegradable absorbent core.

The above water-impermeable film is used as a back sheet,
Equipped with basis weight 15 g / m ² nonwoven topsheet and transport layer, powdery water absorbent 10g and absorbent core made of cellulose fluff, a basis weight of 60 g / m ² nonwoven surge management layer, on one side at both ends of the adhesive sheet backsheet The diaper was made to adhere to each other by a fusion method so that it could be formed, and gathers were attached to the crotch and the waist with fibrous natural rubber.

When the paper diaper was worn on 20 infants and the feel and texture of the paper diaper were subjected to a sensory test, the feel and texture were superior to those of conventional non-biodegradable paper diapers on the market, and urine and loose stool leaked. No, it was confirmed that it was not inferior to conventional non-biodegradable paper diapers.
This paper diaper was buried in soil at 25 ° C and a water content of 30%, and after 3 months, 6 months and 1 year, the degradation status was monitored, and the following results were obtained. Three months later: The shape of the disposable diaper remained, but only the absorbent core was completely disassembled. Six months later: The shape of the disposable diaper had collapsed, but fragments of the film and nonwoven were found in the soil. One year later: No pieces of disposable diapers were visible in the soil. Also, at 60 ° C, the paper diaper was put into compost with a water content of 60% consisting of garbage, fish residues, vegetable waste, etc., and a compost test was performed.One week after the start, the shape of the paper diaper collapsed. After three weeks, no fragments were visible during composting.

Example 2 A water-impermeable film as a back sheet, a nonwoven fabric with a basis weight of 15 g / m ² as a top sheet, an absorbent core containing 1 g of a powdery water-absorbing material and cellulose fluff, a basis weight of 60 g / m, as in Example 1 above. ^{The two} nonwoven fabrics were adhered to each other by a fusion method so that a surge management layer could be provided, thereby preparing a sanitary product composed entirely of biodegradable materials. When this sanitary product was applied to 20 adult women and subjected to a sensory test on the feel and texture, it was confirmed that the feel and texture were better than conventional non-biodegradable sanitary products on the market and were not inferior at all. Was done. This sanitary product was buried in soil at 25 ° C. and a water content of 30%, and the degradation status after 3 months, 6 months and 1 year was monitored. The results were as follows. Three months later: The shape of the sanitary product had collapsed by more than half, and the absorbent core had been completely decomposed. Six months later: The shape of the sanitary product had completely collapsed, but small pieces of film or nonwoven were found in the soil. One year later: No pieces of sanitary products could be visually identified in the soil. Also, the sanitary product was put into compost with a water content of 60% consisting of garbage, fish residues, vegetable waste, etc. at 60 ° C, and a compost test was performed. One week after the start, the shape of the sanitary product collapsed. After 2 weeks, no fragments could be confirmed during composting.

[0064]

Industrial Applicability The biodegradable sanitary article of the present invention has excellent water absorption performance and texture, and has excellent biodegradability in soil and compost.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a conventional disposable diaper.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Top sheet 2 Acquisition layer or transport layer 3 Absorption core part 4 Large management layer 5 Back sheet layer 6 Fibrous natural rubber 7 Adhesive sheet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) A61F 13/472 F-term (Reference) 3B029 BA14 BA17 BB07 BC06 BC07 BD21 4C003 AA23 BA06 DA01 FA01 HA04 4C098 AA09 CC02 CC11 CE02 CE08 CE09 DD10 DD20 DD23

Claims (7)

[Claims] 1. A sanitary article mainly composed of a film, a nonwoven fabric, an adhesive tape, and a water-absorbing material, wherein the film, nonwoven fabric, adhesive tape, and the water-absorbing material have biodegradability, and the water-absorbing material is galactolytic. A biodegradable sanitary article comprising mannan, boron ions, and a trivalent or higher polyvalent metal ion other than boron ions. 2. The biodegradable sanitary article according to claim 1, wherein the film is an impermeable film made of a polylactic acid polymer. 3. The biodegradation according to claim 1, wherein the nonwoven fabric is a nonwoven fabric comprising a polylactic acid polymer fiber or a composite spun fiber of a polylactic acid polymer and a polybutylene succinate polymer. Hygiene products. 4. The water-absorbing material absorbs an aqueous solution of a cation having a valence of not more than 40 times its own weight and having a gel strength of 2 after absorption.
Biodegradable sanitary article according to any one of claims 1 to 3, characterized in that × 10 ^-5 N / mm ² or more. 5. The multivalent metal ion having three or more valences other than boron ion is one or more ions selected from the group consisting of titanium ion, zirconium ion and cerium ion. The biodegradable sanitary article according to any one of the above. 6. The pressure-sensitive adhesive tape according to claim 1, comprising a polylactic acid polymer and a natural rubber-based pressure-sensitive adhesive composition.
5. The biodegradable sanitary article according to any one of 5. 7. The biodegradable sanitary article according to claim 1, wherein the film has a tensile elongation at break of 100% or more and a tensile modulus of elasticity of 1000 MPa or less.