JP2006102227A - Biodegradable sanitary article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable sanitary article having high safety, produced at a low cost, having a favorable external appearance and having a same or superior performance to that of a conventional non-biodegradable sanitary article. <P>SOLUTION: This biodegradable sanitary article is characterized in that the sanitary article is mainly composed of a film, a nonwoven fabric and a water absorbent material; the film, the nonwoven fabric and the water absorbent material are formed of materials with biodegrability; the water absorbent material is a radiation crosslinked substance of a carboxyalkyl cellulose derivative with a yellow index value of 40% or less; and the absorbent material used is the radiation crosslinked substance of the carboxyalkyl cellulose derivative capable of absorbing 0.9 mass% aqueous sodium chloride solution of 30 times or more of its dead weight within one hour, retaining 80% or more of the amount of the absorbed water, and having the gel strength after the water absorption of 2×10<SP>-5</SP>N/mm<SP>2</SP>or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention, for example, absorbs and holds urine or blood composed of a water-absorbing material and a film, nonwoven fabric suitably used for disposable sanitary materials such as disposable diapers, urine-absorbing pads, sanitary napkins, and incontinence pads, and has biodegradability. It relates to sanitary goods that you have.

  Disposable sanitary products using water-absorbing materials are still being used by many manufacturers to improve their structure and configuration, water-absorbing material performance, etc. with the aim of preventing leakage, deodorizing, breathability and improving texture. An application has been filed. Paper diapers and sanitary products basically have an absorbent core made of a water-absorbing material and cellulose fluff between a water-permeable sheet (top sheet) and a water-impermeable sheet (back sheet layer). Alternatively, an end trap part where no absorber is interposed is formed at the thigh root part, and an elastic elastic member is interposed in the end trap part to form a gather, and the paper diaper fits around the waist and the thigh of the wearer To prevent leakage and misalignment. In addition, the urine is unevenly distributed locally and the rapid absorption into the water-absorbing material is impaired, preventing the urine and loose stool from leaking to the outside, and the acquisition layer intended to spread the urine and loose stool uniformly throughout the absorbent core And a multi-layered nonwoven fabric called a transport layer between the top sheet and the absorbent core, or a non-woven fabric called a surge management layer to prevent leakage from the absorbent core to the backsheet layer Has increased. Further, for example, for the purpose of preventing stuffiness during wearing of a paper diaper, the backsheet has been improved such as using a film that is water-impermeable but breathable.

  In recent years, the water-absorbing material in the absorbent core used in such a paper diaper includes a crosslinked polyacrylic acid partial neutralized product (for example, Patent Documents 1 and 2), a starch-acrylonitrile copolymer partial hydrolyzate ( For example, Patent Document 3), starch-acrylic acid graft copolymer (for example, Patent Document 4), hydrolyzate of vinyl acetate-acrylic acid ester copolymer (for example, Patent Document 5), crosslinked isobutylene-maleic anhydride Synthetic polymer water-absorbing materials such as copolymers (for example, Patent Document 6) are known.

  In addition to their substantial capabilities (water absorption and water retention capabilities), these sanitary products are required to have an “appearance” in addition to safety and cleanliness, and are composed of materials that are close to white. Things are sought.

  On the other hand, since synthetic polymer water-absorbing materials are not biodegradable, disposal after use is a problem. Currently, sanitary products containing these synthetic polymer water-absorbing materials are incinerated at the time of disposal and landfilled. However, in the method of incinerator treatment, global warming and acid rain It has been pointed out that it is a source of gas that causes it. In the landfilling method, there are problems that the volume is bulky, the ground does not become stable because it does not rot, and the synthetic polymer remains in the soil forever. In other words, since these resins are derived from fossil fuels, they are poorly decomposable, and if incinerated, they become a source of global warming gas, and exist semipermanently in water and soil, so consider environmental conservation in waste treatment. And it is a very serious problem.

  In recent years, biodegradable polymers have attracted attention as “earth-friendly materials”, and it has been proposed to use them as water-absorbing materials, films, and nonwoven fabrics. Examples of the water-absorbing material having biodegradability include a crosslinked carboxymethyl cellulose (for example, Patent Documents 7 and 8), a crosslinked starch (for example, Patent Documents 9 and 10), and a crosslinked polyamino acid (for example, Patent Documents 11 to 15). ), A galactomannan-polyvalent metal ion crosslinked product (for example, Patent Document 16) and the like are known.

  Films made of polyethylene, polypropylene, and polyester have been used as materials for composing back sheets of disposable diapers and sanitary goods because of their excellent water impermeability. Nonwoven fabric made of cellulose, rayon, polyethylene or the like has been used as a material constituting the water permeable layer such as a water permeable top sheet, an acquisition layer, and a transport layer because of its excellent touch feeling. However, since these components other than cellulose and rayon are not biodegradable, they remain in the soil when landfilling waste after use, so that it is the same as the non-biodegradable water-absorbing material described above. Issues have been raised. Under such circumstances, the development of sanitary products made of materials in which all components are biodegradable has been expected.

  As the water-impermeable film having biodegradability, there are so-called biodegradable plastics, and the main ones are polylactic acid polymer, starch-polycaprolactone copolymer, succinate polymer, poly-3-hydroxy. A butyrate-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 nonwoven fabrics having biodegradability, nonwoven fabrics composed of cellulose and rayon are known.

  By the way, when compared with a non-biodegradable synthetic polymer water-absorbing material, the above-mentioned water-absorbing material with biodegradability is rarely used because of its low water absorption performance and high cost, and is colored yellow. As a result, it has a poor appearance as a sanitary product and has not been used in disposable diapers or sanitary products. For this reason, although a part of biodegradable sanitary goods can be manufactured using a biodegradable film and a nonwoven fabric, it was not put into practical use.

The present inventors have also reported biodegradable water-absorbing materials obtained by crosslinking galactomannan and other polysaccharides with boron ions and trivalent or higher polyvalent metal ions, for example, in Patent Documents 17 and 18, and A biodegradable sanitary product using such a water-absorbing material is reported in Patent Document 19, but the water-absorbing material is colored pale yellow, which is further improved in appearance compared to conventional non-biodegradable sanitary products. Was demanded.
JP 55-84304 A US Patent No. 462501 JP 46-43995 JP-A-51-125468 JP-A-52-14689 US Pat. No. 4,389,513 US Pat. No. 4,650,716 JP 2001-2703 A JP 55-15634 Japanese Patent No. 2744926 JP-A-7-224163 JP 7-309943 A JP-A-8-59820 JP-A-8-504219 JP-A-9-169840 JP-A-8-59891 JP 2002-265672 A JP 2003-17390 A JP 2002-35037 A

  The object of the present invention is to provide a biodegradable sanitary product that solves the above-mentioned problems, has high safety, is inexpensive, has a good appearance, and has the same or better performance than conventional non-biodegradable sanitary products. There is to do.

  As a result of diligent research, the present inventors have found that all the constituent materials have biodegradability, and hygiene products using biodegradable water-absorbing materials manufactured under specific conditions are conventional non-biodegradable hygiene. It has been found that it has a water absorption ability and appearance equal to or better than those of articles, and that the sanitary articles have excellent biodegradability in soil and compost, and the present invention has been completed.

That is, the present invention is a sanitary article mainly composed of a film, a nonwoven fabric, and a water absorbing material, wherein the film, the nonwoven fabric, and the water absorbing material are made of a biodegradable material, and the water absorbing material has a yellow index value of 40% or less. A biodegradable sanitary product characterized by being a radiation cross-linked product of a carboxyalkyl cellulose derivative, preferably having an average degree of ether substitution of the carboxyalkyl cellulose derivative of 0.5 or more. Moreover, in this biodegradable sanitary ware, the water-absorbing material absorbs 0.9 mass% sodium chloride aqueous solution of 30 times or more of its own weight per hour, and 80% or more of the absorbed amount. It can be water retention, and radiation crosslinking of the carboxyalkyl cellulose derivative gel strength after water absorption has more than 2 × 10 ^-5 N / mm2 It is a biodegradable hygiene products, characterized in that it is.

  According to the present invention, all materials are made of biodegradable materials, and hygiene products having excellent absorbability for body fluids such as blood and urine, high safety, and good appearance are produced. it can. In addition, when biodegradable materials derived from plant materials are used as raw materials, the carbon dioxide generated by combustion and landfill is virtually zero (carbon neutral concept), thus preventing global warming and reducing environmental impact. Can also contribute greatly.

  The biodegradable sanitary article of the present invention is mainly composed of (a) an impermeable film portion, (b) a nonwoven fabric portion, and (c) an absorbent core portion.

  The water-impermeable film of the component (a) is mainly used for a back sheet layer of sanitary goods, and has appropriate flexibility, strength, thermal dimensional stability, transparency, hydrophobicity, breathability, A biodegradable plastic film having heat resistance is used. Specific examples of the biodegradable plastic used in this film include, for example, a biodegradable aliphatic polyester-based polymer that can be produced by combining an aliphatic hydroxycarboxylic acid, an aliphatic dihydric alcohol, and an aliphatic dibasic acid. Coalesce 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, and 6-hydroxy. Examples include caproic acid. Furthermore, cyclic esters of aliphatic hydroxycarboxylic acids, such as 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 may 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, and 3-methyl. Examples include -1,5-pentanediol, 1,6-hexanediol, 1,9-nonanediol, neopentyl glycol, polytetramethylene glycol, and 1,4-cyclohexanediol. These may 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, undecanedioic acid, dodecanedioic acid and the like. These aliphatic dibasic acids can be used alone or in combination of two or more.

  Examples of other biodegradable plastics include semi-aliphatic polyester polymers in which terephthalic acid and / or isophthalic acid are partially copolymerized with the above aliphatic polyester polymers, and aliphatic diamines and fatty acids with the above aliphatic polyesters. And polyester amide polymers, starch polymers, polyvinyl alcohol polymers, and cellulose acetate polymers obtained by copolymerization of aromatic aminocarboxylic acids and lactams.

  These polymers include various additives depending on the purpose, such as antioxidants, ultraviolet absorbers, plasticizers, heat stabilizers, flame retardants, mold release agents, inorganic additives, crystal nucleating agents, antistatic agents, Pigments and antiblocking agents can be added.

  Among these biodegradable plastics, a polylactic acid polymer is preferably used from the viewpoint of safety and cost. The polylactic acid-based polymer includes polylactic acid (homopolymer), as well as copolymers and mixtures 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 mixtures thereof. Polylactic acids obtained from these lactic acids may be mixed with each other. Furthermore, 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 having biodegradability and excellent compatibility with polylactic acid are preferably used. Examples include monovalent or polyvalent fatty acid ester plasticizers, monovalent or polyvalent aliphatic alcohol ester plasticizers, polyalkylene glycol plasticizers, aliphatic polyester plasticizers, and the like.

  A known method may be used as a method for obtaining the polylactic acid polymer. For example, dehydration condensation of lactic acid or ring-opening polymerization of a cyclic ester of lactic acid is used. For the purpose of increasing the molecular weight, a small amount of chain extender such as a diisocyanate compound, diepoxy compound, or acid anhydride may be used. The polylactic acid 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 practically used cannot be obtained. If the molecular weight is larger than this, the melt viscosity Becomes high and film formation becomes difficult.

  There is no restriction | limiting in particular as a method of obtaining a biodegradable plastic film, It shape | molds in a film form with a well-known shaping | molding method. Examples of the method include forming into a film by a T-die molding method, an inflation molding method, a calendar molding method, a hot press molding method, and the like. 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.

  Although it will not specifically limit if the thickness of a film is a range which has moderate intensity | strength and flexibility, 5-300 micrometers is preferable and 10-100 micrometers is still more preferable. It is desirable that the film made of these biodegradable plastics has 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.

  Furthermore, inorganic and organic fillers can be added to the polylactic acid polymer in order to improve the breathability of the biodegradable plastic film. 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, silk, diatomaceous earth, titanium and zeolite are preferable. 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, more preferably 10 μm or less, and particularly preferably 0.7 to 5 μm. If the particle size is too large, the fineness of the pores of the film will deteriorate, and if it is too small, the dispersibility in the resin will deteriorate. After forming a planar unstretched sheet, the film becomes porous and becomes air permeable by uniaxially stretching in the longitudinal direction or biaxially stretching in the longitudinal and lateral directions.

  The non-woven fabric of the component (b) is mainly used for top sheets, acquisition layers, transport layers, surge management layers, etc., which are excellent in liquid permeability of sanitary products, and have appropriate flexibility, strength, water permeability. If it is a nonwoven fabric which consists of a biodegradable fiber which has property, heat resistance, and touch, it will not specifically limit. For example, in addition to cellulose fiber, rayon, polylactic acid polymer, starch-polycaprolactone copolymer, succinic acid ester polymer, poly-3-hydroxybutyrate-3-hydroxyvalerate copolymer, poly-β- Non-woven fabrics composed of fibers obtained by single or composite spinning of one or more resin components selected from hydroxybutyric acid polymers, poly-ε-caprolactone polymers, polybutylene succinate polymers, polyesteramide polymers, and the like. It is done.

  The nonwoven fabric used for the top sheet, acquisition layer and transport layer is preferably excellent in liquid permeability and less bulky, and its density is preferably 0.01-1 g / cm @ 3, more preferably 0.05-0.2 g. / cm3. The basis weight is preferably 1 to 50 g / m <2>, more preferably 5 to 20 g / m <2>. When the basis weight is 50 g / m 2 or more, the liquid permeability is poor. On the other hand, in the surge management layer sandwiched between the absorbent core and the back sheet, in order to prevent urine and soft stool from leaking into the back sheet, it is preferable that the liquid permeability is not so excellent, and the basis weight of the nonwoven fabric used varies depending on the fineness. 20 to 200 g / m @ 2 is preferred.

  The absorption core part of the component (c) is composed of a water absorbing material and a cellulose fluff, etc., and quickly absorbs and gels the target liquid in sanitary goods and retains moisture in the gel even when pressurized. It needs to be a thing. Conventionally, non-biodegradable synthetic polymers such as powdered and fibrous polyacrylic acid-based resins have been used as the water-absorbing material, but since these have no biodegradability, in the present invention as a water-absorbing material Cannot be used.

  In the present invention, the water absorbing material is a radiation cross-linked product of a carboxyalkyl cellulose derivative having a yellow index value of 40% or less.

  As the carboxyalkyl cellulose derivative used in the present invention, hydrogen of the hydroxyl group of cellulose is substituted by carboxymethyl group, carboxyethyl group, carboxypropyl group, and preferable carboxyalkyl cellulose is carboxymethyl cellulose, carboxyethyl cellulose. It is. In the carboxyalkyl cellulose, 20% or more, preferably 40% or more of the carboxyl groups are alkali metal salt, ammonium salt or amine salt. Examples of the alkali metal salt include sodium salt, potassium salt, lithium salt and the like, preferably sodium salt. When the ratio of forming the salt is less than the above range, it becomes difficult to form a uniform mixture or aqueous solution with water. There is no particular upper limit on the ratio of salt formation, and 100% salt may be formed.

  The average degree of polymerization of the carboxyalkyl cellulose derivative is not particularly limited, but is practically, for example, 10 to 2,000, preferably 50 to 1,000, and more preferably about 200 to 800.

  The average degree of etherification of the carboxyalkyl cellulose derivative (referred to as the degree of substitution for substituting hydrogen of the hydroxyl group of cellulose with the carboxyalkyl group) is 0.5 or more, preferably 0.8 or more, More preferably, it is 1.1 or more, and the maximum is 3. When the average degree of etherification is less than 0.5, sufficient crosslinking does not occur.

  As the carboxyalkyl cellulose derivative used as a raw material in the present invention, those produced by a known method can be used. For example, the carboxyalkyl cellulose is produced by various methods such as a slurry method (high liquid magnification method) and a kneader method (low liquid magnification method), for example, a step of reacting cellulose and alkali to produce alkali cellulose (mercelization step). Or an arseration step) and a step of reacting with alkali cellulose and monochloroacetic acid to produce carboxyethyl cellulose by reaction of carboxymethyl cellulose or acrylate ester (carboxyalkylation step). Can be manufactured.

  In the present invention, the mixing ratio of the carboxyalkyl cellulose derivative and water when irradiating with radiation is preferably 100 to 1,500 parts by mass, more preferably 500 to 900 parts by mass with respect to 100 parts by mass of the carboxyalkyl cellulose derivative. Part. In general, when a dilute carboxyalkyl cellulose derivative aqueous solution is irradiated with radiation, decomposition takes precedence over crosslinking. However, it is considered that a hydroxyl radical generated from water is generated in a carboxyalkyl cellulose aqueous solution (paste) having a high solid content concentration, and crosslinking proceeds via this radical. The mixed state of the carboxyalkyl cellulose derivative and water is preferably a uniform state. When the mixing ratio of the water exceeds the above range, it is not economical because crosslinking is insufficient or a large amount of energy is required to dry the crosslinked product (gel). On the other hand, when the amount is less than the above range, the generation of hydroxy radicals is small and crosslinking does not proceed, or a water absorbing material having a target performance cannot be obtained.

  Examples of water used in the present invention include city water, industrial water, deaerated water, deionized water, gel filtered water, distilled water, and the like, which inhibits cross-linking by radiation or improves the appearance and safety of the water-absorbing material. It is preferred not to contain any compounds or ions that can be damaged.

  As a radiation source used for the radiation irradiation treatment according to the present invention, α rays, β rays, γ rays, X rays, electron beams, ultraviolet rays, and the like can be used. X-rays are more preferable, and electron beam irradiation treatment using the γ-rays or electron accelerators is particularly convenient for introducing a crosslinked structure.

In the present invention, the amount of radiation to be irradiated cannot be defined unconditionally because it depends on the degree of etherification of the carboxyalkyl cellulose derivative, the molecular weight, the mixing ratio with water and the oxygen atmosphere. It absorbs 0.9% by weight sodium chloride aqueous solution of 30 times or more of its own weight, can retain 80% or more of the absorbed amount, and has a gel strength of 2 × 10 ⁻⁵ N / mm 2 or more after water absorption. It doesn't matter if it does not impair performance.

  The dose of radiation that satisfies such conditions is approximately 1 to 50 kGy, preferably 5 to 20 kGy, more preferably 8 to 15 kGy in terms of γ-ray. If the radiation dose is less than the above range, the gel after water absorption cannot obtain the target gel strength even if cross-linking is performed.For example, the gel after water absorption adheres to the skin when wearing hygienic products containing them. It can not be put to practical use because it feels or the gel leaks from the hygiene product. When the above range is exceeded, the crosslinking proceeds too much, the water absorption capacity and water retention capacity are remarkably lowered, and it cannot be used as a water absorbent material for sanitary goods.

  The drying method of the crosslinked carboxyalkyl cellulose derivative (gel) in the present invention is not particularly limited as long as the water absorption performance is not impaired and the yellow index value is 40% or less. For example, in addition to freeze-drying, drying under reduced pressure, drying with hot air, etc., solvent replacement methods (contacting a hydrophilic volatile organic solvent, dehydrating part or all of the moisture in the gel into the solvent, There is a method of drying after replacing with a solvent. The hydrophilic volatile organic solvent used here is not particularly limited, but may be a lower level such as methyl alcohol, ethyl alcohol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, t-butyl alcohol and the like. Examples include alcohols, ketones such as acetone and methyl ethyl ketone, ethers such as dioxane and tetrahydrofuran, amides such as N, N-dimethylformamide, and sulfoxides such as dimethyl sulfoxide. To lower alcohols such as methanol, ethanol and iso-propyl alcohol.

  A preferred drying method is hot air drying at a low cost, but when dried at 80 ° C. or higher, it is often colored brown, preferably hot air drying at less than 80 ° C., more preferably hot air at less than 70 ° C. It is dry. When the brown coloring is remarkable, even if the basic water absorption performance is not impaired at all, it is unsuitable for use as a sanitary product and is difficult to put into practical use. The yellow and brown color of the water-absorbing material particles are quantified by the yellow index value. Many of the polyacrylates currently on the market have a yellow index of 15% or less, and white is particularly preferred for hygiene products because it gives the user a clean feeling. The yellow index value for preventing the user from feeling unpleasant at least visually is 40% or less, preferably 30%, more preferably 20% or less.

  The shape of the water-absorbing material after drying is not particularly limited, but can be various shapes according to the purpose of use. For example, it is in the form of granules, sheets, powders, fragments, flakes, rods, lines, and the like. These shapes may be crosslinked and dried after the carboxyalkyl cellulose aqueous solution (sol) is molded into the desired shape, or may be dried after the crosslinked gel is molded, and further molded after drying. May be. The shape of the water-absorbing material used for the absorbent core may be any of powder, fiber, film, sheet and the like as long as the target water-absorbing performance is not impaired.

  In addition to the water-absorbing material thus obtained, if necessary, deodorants, fragrances, various inorganic powders, foaming agents, pigments, dyes, antibacterial agents, hydrophilic short fibers, plasticizers, adhesives, surfactants, fertilizers In addition, an oxidizing agent, a reducing agent, water, salts, and the like may be added, thereby imparting various functions to the water absorbing material. Examples of the inorganic powder include substances inert to aqueous liquids, such as fine particles of various inorganic compounds, fine particles of clay minerals, and the like.

  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 depending on the case. When mixing cellulose fluff, the mixing ratio is preferably 5/95 to 95/5, and more preferably 30/70 to 70/30.

  The amount of the water-absorbing material contained in the absorbent core of one sanitary product varies depending on the type of sanitary product. For example, in the case of a paper diaper, 1 to 20 g is preferable, and 5 to 12 g is more preferable. For example, in the case of feminine sanitary products, 0.1 to 5 g is preferable, and 0.5 to 1.5 g is more preferable.

  The pressure-sensitive adhesive sheet is used for adhering to an undergarment for wearing a sanitary product, or for adhering the front and back of a back sheet at a waist portion so that a paper diaper is not removed. An adhesive sheet is comprised from the biodegradable plastic film part as a base material, and an adhesive part. The biodegradable film as the substrate is the biodegradable plastic film used in the above (a), and a polylactic acid polymer stretched film is preferable from the viewpoint of excellent strength. The pressure-sensitive adhesive is not particularly limited as long as it has biodegradability. For example, a pressure-sensitive adhesive composition using a rubber component such as natural rubber or isoprene rubber as a base material and a natural rosin tackifier added thereto is used. Can do. Examples of the method for applying the pressure-sensitive adhesive composition on the substrate include known coating methods such as a roll coater method, a dipping method, a brush coating method, and a spray method. The thickness of the adhesive is preferably 2 to 200 μm.

  In the case of disposable diapers and urine pads, in order to prevent leakage of urine and loose stool from the crotch and waist, the backsheet and top sheet of the disposable diaper corresponding to the crotch and waist are made of raw rubber. It is also possible to equip a gather using a degradable elastic material.

  The components (a) to (c) described above can be bonded and fixed to each other by a known method such as hot melt bonding or thermal bonding to produce a sanitary article. In some cases, for the purpose of preventing leakage and improving the mobility of the wearer, a gather (elastic portion) or the like may be provided around the limbs of the disposable diaper or the urine collecting pad using a biodegradable material. The paper diaper described in the present specification also includes a pants-type paper diaper that is used when urinating or defecation is performed on an infant.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to a present Example. In addition, the characteristic of the water absorbing material was measured by the following method.
[Measurement of water absorption]
The water absorption was measured by a tea bag method using a 0.9% by mass aqueous sodium chloride solution. That is, 1 g of a water-absorbing material is put into a 250 mesh nylon tea bag, the tea bag is immersed in 1 L of 0.9 mass% sodium chloride aqueous solution for 1 hour, the tea bag is pulled up, drained for 10 minutes, It was measured. The water absorption amount of the water absorbing material is the mass of the tea bag without water absorbing material soaked in water for 1 hour, and the mass of the water absorbing material before swelling from the mass of the tea bag containing the water absorbing material swollen after absorbing water And the value obtained by dividing the mass of the blank by the mass of the water-absorbing material before swelling was defined as the water absorption (g / g resin).

[Measurement of water retention amount]
The tea bag (with water-absorbing gel) after measuring the mass in the 1 hour water absorption measurement test of (1) above is centrifuged at 1500 rpm for 5 minutes, and the tea bag after centrifugation (with water-absorbing gel) Measure the mass of The mass after centrifugation of the tea bag without water-absorbing material soaked in water for 1 hour is blank, and from the mass after centrifugation of the tea bag with water-absorbing material swollen after absorbing water, the mass of the water-absorbing material before swelling and The value obtained by dividing the value obtained by reducing the mass of the blank by the mass of the water-absorbing material before swelling was defined as the water retention amount (g / g resin).

[Measurement of gel strength]
The gel strength is measured by immersing the water-absorbing material particles sieved to 200 to 1,000 μm in accordance with the water-absorbing magnification obtained in advance in a 0.9% by mass sodium chloride aqueous solution while stirring, and absorbing water for 1 hour. Viscoelasticity G * was measured at 1 Hz and room temperature using a Rheometric SR-5000 manufactured by the company, and the value was taken as the gel strength.

[Measurement of Yellow Index]
The yellow index value of the 200-1000 μm particles obtained by drying was measured using a color difference meter (Nippon Denshoku Industries Co., Ltd .: Z-Σ90 color measuring system).

Example 1
A polymer obtained by polymerizing a polybutylene succinate polymer synthesized from 1,4-butanediol having a melting point of 118 ° C. and succinic acid by a urethane bond (Bionore, Showa Kogyo Co., Ltd.) with a sheath component and a melting point of 165 The resin component was heated and dissolved at 210 ° C. using a core-sheath compound spinning mold in a melt extruder, using polylactic acid polymer at 0 ° C. as a core component, extruded from a large number of fine holes, 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 opened while being drawn with a high-speed air by an ejector, and collected and deposited on a moving wire collecting support to form a web. The obtained long fiber filaments had an average fineness of 1.5 dtex, a basis weight of 15 g / m @ 2, and a density of 0.1 g / cm @ 3. The web is introduced between a concavo-convex roll heated to 110 ° C. and a smooth roll, and a portion corresponding to the convex portion of the concavo-convex roll is fused at a linear pressure of 30 kg / cm, thereby producing a biodegradable water permeable span. A bond nonwoven fabric was obtained. Using the same method as described above, a biodegradable spunbonded nonwoven fabric having an average fineness of 1.5 dtex and a basis weight of 60 g / m 2 was obtained.

  (A) 74 parts by mass of polylactic acid polymer having a mass average molecular weight of 200,000 (manufactured by Cargill Dow Polymers, EcoPLA4030D) as a polylactic acid raw material from a hopper port of a twin-screw kneader having a diameter of 45 mm, and (B) ) 10 parts by mass of silica having an average particle diameter of 3 μm (manufactured by Fuji Silysia Co., Silicia) and 1 part by mass of (C) erucic acid amide (manufactured by Nippon Oil & Fats Co., Ltd., Alfro P10) were charged while being measured by a mass type feeder. Further, 15 parts by mass of (D) polyethylene glycol having an average molecular weight of 400 (manufactured by Sanyo Chemical Co., Ltd., Sunfine DM400) having both ends blocked with methoxy as a plasticizer was quantitatively injected from the middle of the cylinder with a liquid metering pump. After melt-kneading (A) to (D) at a temperature of 180 ° C. to 190 ° C., the composition extruded in a strand shape was cooled in a water bath and cut into a pellet shape. The pellets of the polylactic acid composition thus obtained were dried at 40 ° C. under reduced pressure for 8 hours. The dried pellets were melted at a temperature of 180 ° C. using a single screw extruder having a diameter of φ50 mm, extruded from a T-die into a sheet shape, and rapidly cooled with a casting roll to obtain an unstretched sheet having a thickness of 25 μm. The tensile modulus of the film obtained by stretching the film thus obtained by 220% was measured according to JIS K6732, and was 550 Mpa.

  A biodegradable film having a thickness of 200 μm was obtained using the same method as described above, and a pressure-sensitive adhesive composition having a natural rubber base material on one surface and a natural rosin tackifier added thereto was 20 μm thick by a roll coater method. A biodegradable pressure-sensitive adhesive sheet was obtained by applying to the surface.

20 g of sodium carboxymethyl cellulose (manufactured by Daicel Corporation, average degree of etherification 1.3) was sufficiently kneaded using 80 g of water and a hybrid mixer (manufactured by Keyence Corporation) to obtain a uniform sol having a solid content concentration of 20% by mass. This sol was put into a nylon bag so as to have a thickness of 2 cm, and was irradiated with gamma rays so as to have an irradiation amount of 8 kGy to be crosslinked and gelled. The obtained gel was cut and dried with hot air at 70 ° C., and the obtained dried product was crushed to 1 mm or less with a Wonder Crush Mill (manufactured by Osaka Chemical Co., Ltd.) to obtain a water absorbing material. This was classified and the water absorption amount, water retention amount, gel strength (gel viscoelasticity G *), and yellow index value were measured for the water absorbing material in the range of 200 to 1000 μm. As a result, the water absorbing material of this example had a water absorption amount of 42 g / g, a water retention amount of 37 g / g, a gel strength of 5.2 × 10 ⁻⁴ N / mm 2, and a yellow index value of 35%. Further, no gel leakage from the nylon bag was observed, and all the gel after water absorption was present in the form of particles, and no tackiness was observed between the particles. The mixing ratio of this water absorbing material and cellulose fluff was 20/80, and a biodegradable absorbent core was prepared.

  The above-mentioned water-impermeable film is a back sheet, a nonwoven fabric with a basis weight of 15 g / m 2 is a top sheet and a transport layer, an absorbent core made of 10 g of powdered water absorbent and cellulose fluff, a nonwoven fabric with a basis weight of 60 g / m 2 is a surge management layer, and an adhesive sheet Were attached to each other by fusing so that they could be installed on both ends of the backsheet, and gathered on the crotch and waist with fibrous natural rubber to create a disposable diaper consisting entirely of biodegradable materials.

  When this paper diaper was worn on 20 adults and the appearance, feel, and texture were subjected to a sensory test, the appearance, feel, and texture were equivalent to or better than conventional non-biodegradable paper diapers, and urine and loose stools It was confirmed that there was no leakage and that it was not inferior to conventional non-biodegradable paper diapers.

  The paper diaper was embedded in soil with a water content of 30% at 28 ° C., and the degradation status was monitored after 3 months, 6 months and 1 year, and the following results were obtained.

  Three months later: The shape of the disposable diaper remained, but only the absorbent core portion was completely disassembled. After 6 months: The shape of the disposable diaper had collapsed, but fragments of the film and nonwoven fabric were confirmed in the soil. One year later: All pieces of disposable diapers could not be visually confirmed in the soil.

In addition, when the paper diaper was put into a compost having a moisture content of 60% composed of leftover rice, fish residue, vegetable scraps, etc. at 60 ° C. and a compost test was conducted, the shape of the paper diaper collapsed after 2 weeks from the start, After 4 weeks, no fragments could be confirmed during composting.

Claims (3)

Radiation of a carboxyalkyl cellulose derivative that is a sanitary product mainly composed of a film, a nonwoven fabric, and a water-absorbing material, wherein the film, the nonwoven fabric, and the water-absorbing material are composed of biodegradable materials, and the water-absorbing material has a yellow index value of 40% or less. A biodegradable sanitary article characterized by being a crosslinked product. The water-absorbing material can absorb 0.9 mass% sodium chloride aqueous solution of 30 times or more of its own weight per hour and can retain 80% or more of the absorbed amount, and the gel strength after water absorption is 2 × 10. ^The biodegradable sanitary article according to claim 1, which is a radiation cross-linked product of a carboxyalkyl cellulose derivative having ^-5 N / mm 2 or more. The biodegradable sanitary article according to claim 1 or 2, wherein the carboxyalkyl cellulose derivative has an average degree of ether substitution of 0.5 or more.