JP2016013687A - Stretchable composite material that feels good - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stretchable composite member which realizes thinness and lightness reducing effects on the outer wear in wearing, together with good fitness to the human body, slip-down preventive performance, soft and good skin touch and reduced irritation and is suitable paper diapers.SOLUTION: A stretchable composite material is formed by arranging a plurality of polyurethane elastic fibers between a pair of nonwoven fabrics and joining together with a hot melt adhesive, has a gather-like irregular structure formed perpendicularly to the extention direction and is stretchable in at least one direction. The stretchable composite material has a basis weight of 50-200 g/m, a thickness of 0.5-5 mm and a full elongation rate of 50-300%.

Description

  The present invention relates to a stretchable composite material that is thin, soft, and soft to the touch. More specifically, the present invention relates to a stretchable composite material suitable for an abdomen gathered portion of a paper diaper, which is excellent in appearance aesthetics, soft and soft to the touch, and excellent in fit.

  In sanitary material applications such as disposable diapers, gather-like stretchable materials are used for the abdomen, waist, legs, and the like. The performance required for the stretchable material is required to have a stretchable property that fits well to the body and maintains an appropriate range of pressure without slipping or excessive tightening when worn. In addition, since the skin is directly touched with an appropriate range of pressure, the stretchable material is required to have a thin and soft performance with good touch and low irritation to the skin. Further, in recent years, in so-called light incontinence adult paper diapers, in many cases, activities are carried out by wearing outerwear such as trousers and skirts while wearing diapers as underwear, and it is difficult to slip off during activities, and It is required that the worn diaper is not conspicuous over the outerwear, and the stretchable material used for these diapers is required to have both unprecedented thinness and anti-slip performance and aesthetic appearance. It is like that.

Various studies have been conducted so far to obtain a stretchable material.
The following Patent Document 1 discloses a composite having a fine folded structure obtained by stretching a composite made of a composite spunbond nonwoven fabric and a stretchable layer.
Patent Document 2 below discloses a method for producing a stretchable sheet by subjecting a nonwoven fabric composed of stretchable fibers and stretchable fibers to gear stretching.
Furthermore, Patent Document 3 below discloses a stretchable nonwoven fabric in which elastic fibers are bonded to one surface of a layer containing elastic fibers.
However, in these stretchable materials, the stretchable fiber component is stretched mainly by stretching the nonwoven fabric, and the stretchability is manifested by the kickback of the stretchable fiber component. There was a limit to the elongation rate, and sufficient fitting performance and slip-off prevention performance could not be satisfied.

  On the other hand, in Patent Document 4 below, the production of a stretchable nonwoven fabric for paper diapers characterized in that a large number of elastic yarns are inserted and fixed between nonwoven fabrics from an elastic yarn beam winding body in which a large number of elastic yarns are arranged in parallel. A method is disclosed. The method of inserting and fixing a large number of elastic yarns between the nonwoven fabrics is preferable from the viewpoint of satisfying sufficient fitting performance and slip-off prevention performance. However, an excessive tightening force is expressed by inserting and fixing a large number of elastic yarns, and in addition, unevenness in the gathered portion may become excessive, which may increase the irritation to the skin and may be soft. From the viewpoint of good touch and low irritation to the skin, it was not always satisfactory.

  Furthermore, Patent Document 5 below discloses an elastic body in which a large number of elastic yarns are arranged in parallel and bonded to a polypropylene spunbonded nonwoven fabric by thermal bonding. However, in the present invention, since it is combined and integrated with the elastic yarn by thermocompression bonding, in order to obtain a sufficient bonding force, it is necessary to increase the melted part, so that it becomes a hard texture, the gather part The undulations were large and the touch was bad. Furthermore, if the thermocompression bonding portion is reduced in order to obtain a soft texture, the adhesion with the elastic yarn is not sufficient, and the elastic yarn and the nonwoven fabric are peeled off, so that a sufficient elastic material cannot be obtained.

JP 2011-231444 A Japanese Patent No. 5238158 JP2012-132115A Japanese Patent Laying-Open No. 2005-320636 Japanese Patent No. 2892106 Japanese Patent Laid-Open No. 5-155842

  The problems to be solved by the present invention include a good fit performance to the body and an anti-slip performance, a soft and soft touch and low irritation to the skin, as well as a thinness and lightness that does not resonate with the outer when worn. It is providing the expansion-contraction member which can be used conveniently for the paper diaper implement | achieved.

  Furthermore, the present invention provides a stretchable member that has good creep performance and prevents the elastic yarn and the nonwoven fabric from peeling off during use of the paper diaper or during storage.

  As a result of intensive studies and repeated experiments to solve the above problems, the present inventors have identified the rigidity of the nonwoven fabric, the polyurethane elastic yarn insertion method, and the joining method in the stretchable member joined with the nonwoven fabric and the polyurethane elastic fiber. In addition to a good fit performance to the body and anti-slip performance, soft and soft touch and low irritation to the skin, it should be thin and light so that it does not resonate with the outer when worn. As a result, the present invention has been completed. That is, the present invention is as follows.

[1] A plurality of polyurethane elastic fibers are arranged between a pair of non-woven fabrics and stretched in at least one direction having a gather-like concavo-convex structure formed perpendicularly to the extension direction obtained by bonding with a hot melt adhesive. A stretchable composite material, wherein the basis weight is 50 g / m ² or more and 200 g / m ² or less, the thickness is 0.5 mm or more and 5 mm or less, and the stretch elongation is 50% or more and 300% or less. Elastic composite material.
[2] The stretchable composite material according to [1], wherein the gather-like uneven structure has a pitch of 0.5 mm to 10 mm.
[3] The expansion and contraction according to [1] or [2], wherein the compression work in the thickness direction is 0.20 gf · cm / cm or more and the thickness change under a compression load is 0.5 mm or more. Composite material.
[4] The stretchable composite material according to any one of [1] to [3], wherein a friction coefficient when rubbing in the extension direction is 0.1 or more and 0.8 or less.

  Furthermore, the present inventors, when joining a plurality of polyurethane elastic fibers between non-woven fabrics, by applying a hot melt adhesive in a fibrous form, good fit performance to the body and slip-off prevention performance, soft and It has been found that, in addition to the performance that is soft to the skin and low in irritation to the skin, it achieves the thinness and lightness that do not resonate with the outer when worn, and the creep performance of an elastic member suitable for use in disposable diapers.

  In accordance with the present invention, it is suitable for paper diapers that combine thinness and lightness that do not resonate with the outer when worn, in addition to good fit performance to the body and anti-slip performance, soft touch and low skin irritation It is possible to provide a stretchable member that can be used for the above.

(Combination method of nonwoven fabric and polyurethane elastic fiber)
The elastic composite material of this embodiment is an elastic material that expands and contracts in one direction, in which a nonwoven fabric and polyurethane elastic fiber are joined. As a form of joining of the nonwoven fabric and the polyurethane elastic fiber, for example, the polyurethane elastic fiber may be joined to one side of one nonwoven fabric, and then joined to the nonwoven fabric. After the polyurethane elastic fiber is joined to both sides of one nonwoven fabric, Other nonwoven fabrics may be joined to the surface facing each nonwoven fabric, or polyurethane elastic fibers may be inserted and joined between the two nonwoven fabrics. However, it is preferable to insert a plurality of polyurethane elastic fibers between a pair of nonwoven fabrics.

As a method of joining the nonwoven fabric and the polyurethane elastic fiber, a method of joining the nonwoven fabric and the polyurethane elastic fiber using a hot melt adhesive, or a method in which a part or all of the nonwoven fabric and / or the polyurethane elastic fiber is melted by heat and joined. By this method, the nonwoven fabric and the polyurethane elastic fiber can be joined. Among these, bonding using a hot melt adhesive is preferable from the viewpoint of the softness of the stretchable composite material.
The whole surface of the nonwoven fabric and the polyurethane elastic fiber may be continuously joined in the longitudinal direction of the polyurethane elastic fiber, or may be intermittently partially joined in the longitudinal direction of the polyurethane elastic fiber. In addition, a material other than the nonwoven fabric and the polyurethane elastic fiber may be inserted, affixed, and coated as long as the object of the present invention is not impaired.

(Expression method of stretchable structure)
There is no particular limitation on the method of joining the nonwoven fabric and the polyurethane elastic fiber to obtain a stretchable composite material, and conventionally known methods can be applied. For example, a method of obtaining a stretchable composite material by expressing a gather-like structure by loosening the elongation of the polyurethane elastic fiber after bonding the polyurethane elastic fiber previously stretched with the nonwoven fabric, or joining the nonwoven fabric and the polyurethane elastic fiber. Then, after stretching at the meshing portion between two rolls with a difference in speed or between the rolls on the uneven gear, a gather-like structure may be expressed by loosening the stretch of the nonwoven fabric.

(Physical properties of stretchable composite materials)
The elastic composite material needs to have a basis weight of 50 g / m ² or more and 200 g / m ² or less. If the basis weight is 50 g / m ² or more, it has sufficient strength as a stretchable material used for sanitary materials, and if the basis weight is 200 g / m ² or less, it satisfies the lightness when used for sanitary materials. can do. From the viewpoint of a balance between sufficient strength and lightness when used as a sanitary material, the basis weight is preferably 80 g / m ² or more and 150 g / m ² or less.
The stretchable composite material needs to have a thickness of 0.5 mm or more and 5 mm or less. If the thickness is 0.5 mm or more, it has sufficient strength as a stretchable material used for sanitary materials and the like, and if the thickness is 5 mm or less, it can satisfy the thinness when used for sanitary materials and the like.
Furthermore, the stretchable composite material needs to have an “extension / extension ratio” of 50% or more and 300% or less when stretched from an unstrained state (relaxed state) until the nonwoven fabric breaks. If the elongation / extension rate is 50% or more, a good fit performance to the body can be satisfied, and if the elongation / extension rate is 300% or less, the slip prevention performance is satisfied when used for sanitary materials. be able to.

(How to arrange polyurethane elastic fibers)
It is preferable that two or more polyurethane elastic fibers are simultaneously bonded to the nonwoven fabric in the stretchable composite material in which the polyurethane elastic fibers are bonded to the nonwoven fabric. At this time, the polyurethane elastic fibers may be joined to the nonwoven fabric in a state of being arranged in parallel, may be arranged in an arc shape, a parabola shape, a zigzag shape, a sinusoidal shape, or the like, or a combination thereof. May be. In order to reduce the pitch of the gather-like structure of the stretchable composite material, and to provide a stretchable material that has good touch and low irritation to the skin, it is preferable that the polyurethane elastic fibers are joined to the nonwoven fabric in a state of being arranged in parallel. .
When joining with a nonwoven fabric in a state where two or more polyurethane elastic fibers are arranged, the polyurethane elastic fibers can be arranged at an arbitrary interval. In view of the uniformity of the gather-like structure of the stretchable composite material, the polyurethane elastic fibers are preferably arranged at intervals of 10 mm or less, more preferably at intervals of 5 mm or less, and further at intervals of 2 mm or less. preferable. The polyurethane elastic fiber can be bonded to the non-woven fabric in a stretched state at an arbitrary stretch rate as required.

(Types of polyurethane elastic fiber)
The polyurethane elastic fiber used for the stretchable composite material is a stretchable fiber made of a polymer having polyurethane or polyurethaneurea as a main structural unit (hereinafter referred to as a polyurethane polymer).
For example, a polyurethane-based polymer can be synthesized by reacting a polymer glycol having a number average molecular weight of 600 to 5,000 with an organic diisocyanate to synthesize a urethane intermediate polymer that becomes a soft segment, and then a chain extension having a polyfunctional active hydrogen atom. It can be produced by using a known technique in which a hard segment is polymerized with an agent and endcapped with a terminal terminator having a monofunctional active hydrogen atom. When a low molecular weight diol is used as the chain extender, a polyurethane polymer whose hard segment is a urethane bond can be obtained, and when a bifunctional amine is used, a polyurethane urea polymer whose hard segment is a urea bond can be obtained.

  Examples of the polymer glycol include homopolyether diols such as polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol and polyoxypentamethylene glycol, and two or more oxyalkylenes having 2 to 6 carbon atoms. Copolymerized polyether diol, adipic acid, sebacic acid, maleic acid, itaconic acid, azelaic acid and malonic acid and one or more dibasic acids and ethylene glycol, 1,2-propylene glycol, 1,3 -Propylene glycol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, hexamethylene glycol, diethylene glycol, 1,10-decanediol, 1,3-dimethylol Siku Polylactone diols such as polyester diol, polyester amide diol, polyester ether diol, poly-ε-caprolactone diol, and polyvalerolactone diol obtained from one or more of glycols such as hexane and 1,4-dimethylolcyclohexane Polycarbonate diol, polyacryl diol, polythioether diol, polythioester diol, or a copolymer or mixture of these diols. In order for the stretchable composite material to have sufficient fitting performance and slip-off prevention performance, the polymer glycol may be polyoxytetramethylene glycol or a polyoxytetramethylene glycol having a different number of carbon atoms, preferably a branched alkylene group. A copolymerized polyether diol obtained by copolymerizing a glycol having the following formula is preferred.

  Examples of the organic diisocyanate include 4,4′-methylenebis (phenylisocyanate), methylenebis (3-methyl-4,1-phenylene) diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, m- And p-xylylene diisocyanate, α, α, α ′, α′-tetramethyl-xylylene diisocyanate, m- and p-phenylene diisocyanate, 2,4-dimethyl-1,3-bis (isocyanatomethyl) benzene, 1-alkyl-2,4 and 2,6-phenylene diisocyanate, 3- (2-isocyanatoethyl) phenyl isocyanate, 2,6-diethyl-1,4-phenylene diisocyanate, [isopropylidenebis (p-phenylene)] Diisocyanate, diphenyl ether -4,4'-diisocyanate, 1,5-naphthalene diisocyanate, 1,6-hexamethylene diisocyanate, methylene bis (4-cyclohexyl-4,1-phenylene) diisocyanate, 1,3- and 1,4-cyclohexylene diisocyanate, Examples include propylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, or a mixture thereof.

  Examples of the chain extender having a polyfunctional active hydrogen atom include, for example, hydrazine, polyhydrazine, an amino group having a linear or branched aliphatic, alicyclic or aromatic active hydrogen having 2 to 10 carbon atoms. Compounds having, for example, ethylenediamine, 1,2 propylenediamine, diamines such as diamines having a urea group described in Patent Document 6, hydroxylamine, water, low molecular weight glycols such as ethylene glycol, 1,2- Propylene glycol, 1,3-propylene glycol, 2,2-dimethyl-1,3-propanediol, 1,4-butanediol, 1,3-butanediol, hexamethylene glycol, diethylene glycol, 1,10-decanediol, 1,3-dimethylolcyclohexane, 1,4-dimethylolcyclohex It can be used down the like. Preferred are ethylenediamine and 1,2-propylenediamine.

Examples of the terminal terminator having a monofunctional active hydrogen atom include dialkylamines such as diethylamine and alkyl alcohols such as ethanol. These chain extenders or end terminators may be used alone or in combination of two or more.
This polyurethane polymer includes other compounds usually used for polyurethane elastic fibers, such as UV absorbers, antioxidants, light stabilizers, chlorine embrittlement resistance, gas resistance stabilizers, colorants, matting agents. Further, a filler or the like may be added.

  The polyurethane polymer thus obtained can be formed into a fiber shape by known dry spinning, wet spinning, melt spinning, etc. to produce polyurethane elastic fibers. The polyurethane elastic fiber may be a monofilament or a multifilament, and one filament constituting the multifilament may be composed of a single polyurethane polymer or two or more types of polyurethane polymers. May be. At this time, two or more types of polyurethane polymers may be completely mixed and spun to form a polyurethane elastic yarn, or one filament made of one polyurethane polymer is coated with another polyurethane polymer. A sheath-core structure polyurethane elastic fiber or a sea-island structure polyurethane elastic fiber in which a plurality of filaments made of one polyurethane polymer are coated with another polyurethane polymer may be used.

The fineness of the polyurethane elastic fiber is not limited, but 10 dtex to 300 dtex is preferable, 20 dtex to 200 dtex is more preferable, and 40 dtex to 100 dtex is particularly preferable in order to achieve both softness and softness that fits the body.
Polyurethane elastic fiber obtained, polydimethylsiloxane, polyester-modified silicone, polyether-modified silicone, amino-modified silicone, mineral oil, mineral fine particles such as silica, colloidal alumina, talc, etc., higher fatty acid metal salt powder, such as Oils such as solid waxes at room temperature such as magnesium stearate and calcium stearate, higher aliphatic carboxylic acids, higher aliphatic alcohols, paraffin, polyethylene, etc. may be applied alone or in any combination as required.

(Nonwoven fabric)
There is no restriction | limiting in particular in the kind of nonwoven fabric used for the elastic composite material of this embodiment, Long fiber nonwoven fabrics, such as a spun bond type nonwoven fabric, a melt blown type nonwoven fabric, a flash spinning type nonwoven fabric, an electrostatic spinning type nonwoven fabric, and a wet spinning type nonwoven fabric It may be a short fiber nonwoven fabric obtained by a wet papermaking method.
Although there is no limit to the basis weight of the nonwoven fabric, or if the basis weight is in order to obtain 50 g / m ² or more 200 g / m ² or less of the stretchable nonwoven member, for example, the polyurethane elastic fibers are bonded to both sides of one of the nonwoven fabric, When polyurethane elastic fibers are bonded to one side of one nonwoven fabric, the basis weight of the nonwoven fabric is preferably 20 g / m ² or more and 100 g / m ² or less, and the polyurethane elastic fibers are bonded between the two nonwoven fabrics. In that case, the basis weight of one nonwoven fabric is preferably 10 to 50 g / m ² or less.

  There is no restriction | limiting in particular in the fiber which comprises a nonwoven fabric, Polyolefin fibers, such as polyethylene and a polypropylene, A polyester fiber, a polyamide fiber, a cellulose fiber, a polyurethane fiber, etc. may be sufficient, and what mixed these may be sufficient. You may use the nonwoven fabric which consists of a different fiber in combination of 2 or more types. As the nonwoven fabric used for the stretchable material suitably used for the sanitary material, a polyolefin-based long fiber nonwoven fabric is preferable. As the polyolefin fibers constituting the polyolefin long fiber nonwoven fabric, for example, fibers made of resins such as polyethylene, polypropylene, copolymers of those monomers and other α-olefins, and the like can be used. Among these, it is preferable to use a polypropylene fiber made of polypropylene or a polypropylene copolymer because it is strong and hardly broken and has excellent dimensional stability when producing an elastic material.

  In order for the stretchable composite material to have good flexibility, the nonwoven fabric used preferably has high flexibility. In order to impart high flexibility to the polyolefin-based long-fiber nonwoven fabric, a partial thermocompression bonding method is preferable as a joining means when long fibers are joined to form a nonwoven fabric, and the partial thermocompression-bonding area ratio is preferably small. Further, the smaller the average single yarn fineness of the polyolefin long fibers constituting the nonwoven fabric, the higher the flexibility. At the same time, however, the spinning stability deteriorates, so the average single yarn fineness is 0.5 dtex or more and 3.0 dtex or less. Preferably, it is 0.7 dtex or more and 2.0 dtex or less, and more preferably 0.7 dtex or more and 1.4 dtex or less. In order to obtain good flexibility, the polyolefin-based long fiber nonwoven fabric may be subjected to uneven forming. As the shape of the forming process, a straight line, a curved line, a corner, a circle, a satin-like shape, and other continuous and non-continuous shapes can be applied. Furthermore, in order to obtain good flexibility, an ester compound of a tri- to hexavalent polyol and a monocarboxylic acid may be imparted to the polyolefin-based long fiber nonwoven fabric. The ester compound may be mixed with a polyolefin-based resin and then spun to obtain a polyolefin-based long fiber nonwoven fabric, or the ester compound may be applied after obtaining a polyolefin-based long fiber nonwoven fabric.

The nonwoven fabric used for the elastic composite material may be provided with a hydrophilizing agent. In addition, the fibers constituting the nonwoven fabric used for the stretchable composite material may contain a nucleating agent, a flame retardant, an inorganic filler, a pigment, a colorant, a heat stabilizer, an antistatic agent, etc., as long as the object of the present invention is not impaired. You may mix | blend.
In the present invention, in order to achieve a stretchable material that is excellent in appearance aesthetics, soft and soft, and has good fit, the nonwoven fabric used is formed following the expansion and contraction of elastic fibers. The shape of the concavo-convex structure is important. The nonwoven fabric forms a gathered concavo-convex structure by elastic fiber expansion / contraction, but if the bending stiffness of the nonwoven fabric is excessive, the elastic pitch does not follow the elastic fiber expansion / contraction, the elastic material is thick, and the concavo-convex structure The shape is uneven and the appearance is inferior in aesthetics. Furthermore, when it rubs, it will become a rough feel, a friction coefficient is high, and it will become a bad touch. In order to obtain the stretchable composite material of the present embodiment, the flexural rigidity of the nonwoven fabric is 80 mm or less, preferably 70 mm or less, more preferably 60 mm or less. When the bending stiffness of the nonwoven fabric is within the above range, the gather-like uneven structure has a fine uniform structure of 0.5 mm to 10 mm following the expansion and contraction of the elastic fiber, has a good touch, and is uniform and aesthetic in appearance. It will be excellent.

The soft stretchable composite material according to the present embodiment is important for its softness when compressed by contact pressure. The softness when compressed is indicated by the amount of compression work in the thickness direction and the thickness change under a compression load. The compression work is preferably 0.2 gf · cm / cm or more, and the thickness change under a compression load is preferably 0.5 mm or more. The elastic composite material that is soft during compression fits to the body structure due to collapse of the concavo-convex structure due to contact pressure. As a result, the contact area between the skin and the stretchable material is increased, and even if the applied pressure is not increased, it is difficult to slip off during activity, and the skin is smooth and soft to the touch. Furthermore, it is thin and does not stand out when worn, and the aesthetics of the appearance are excellent.
When the compression work is less than 0.2 gf · cm / cm and the thickness change under a compression load is less than 0.5 mm, the uneven structure due to contact pressure is difficult to be deformed, and the touch becomes poor. Moreover, it becomes inadequate in the softness at the time of wear. On the other hand, the compression work is 3.0 gf · cm / cm or less from the viewpoint of the fit of the gathered concavo-convex structure, and the thickness change under the compressive load is maintained even when the gathered concavo-convex structure is applied. From the viewpoint, it is 5.0 mm or less. When the compression work exceeds 3.0 gf · cm / cm, the gather-like uneven structure becomes excessively bulky, and the fitting property is deteriorated when worn. Moreover, if the thickness change under a compressive load exceeds 5.0 mm, a gather shape will be easily crushed with the pressure at the time of wear, and the softness which is plump will be impaired. Moreover, the uneven structure in which the thickness change exceeds 5.0 mm has an excessive thickness when it becomes a gathered shape, has poor fit when worn, and is inferior in appearance aesthetics.

In the stretchable composite material according to this embodiment, in order to achieve a stretchable material having a good touch, it is preferable that the friction coefficient when rubbing in the extending direction is 0.1 or more and 0.8 or less. If the coefficient of friction is less than 0.1, it will easily slip off during operation when worn. Moreover, when a friction coefficient exceeds 0.8, it will become rough.
Further, in order to achieve fit as an elastic composite material and an appropriate range of pressure, the stress at the time of 3% elongation of the nonwoven fabric is preferably 2 N / 5 cm or more and 10 N / 5 cm or less, more preferably It is 2.5 N / cm or more and 7.5 N / 5 cm or less. When it is 2 N / 5 cm or less, it is not preferable because it tends to change in size due to tension when bonded as an elastic material. In addition, since the nonwoven fabric is excessively soft in the gathered concavo-convex structure, the stretchable composite material becomes thin and hard at the time of compression.

(Joining method)
In the stretchable composite material according to this embodiment, from the viewpoint of softness, it is preferable to join the nonwoven fabric and the polyurethane elastic fiber with a thermoplastic material, and preferably using a hot melt adhesive. As the bonded state, the entire surface of the nonwoven fabric and polyurethane elastic fiber may be bonded continuously in the longitudinal direction of the polyurethane elastic fiber, or may be intermittently partially bonded in the longitudinal direction of the polyurethane elastic fiber. Good. In addition, a material other than the nonwoven fabric and the polyurethane elastic fiber may be inserted, affixed, and coated as long as the object of the present invention is not impaired.
In hot melt bonding of non-woven fabric and elastic fiber, if the bonding is weak, the gathered uneven structure becomes non-uniform and the touch becomes poor.
On the other hand, if the amount of hot melt adhesive is excessive, it becomes stiff during compression and the softness during wearing becomes insufficient. Furthermore, the adhesive penetrates into the nonwoven fabric, the nonwoven fabric is bent and rigid, the pitch of the gathered uneven structure is large, and the touch is poor. Along with this, the fit to the skin is also inhibited.

(Hot melt adhesive)
In the present embodiment, it is preferable to use a hot melt adhesive mainly composed of a thermoplastic elastomer. Hot-melt adhesives mainly composed of thermoplastic elastomers include rubber hots that use block copolymers of vinyl aromatic hydrocarbons and conjugated diene compounds, and styrene block copolymers made of hydrogenated products thereof. Melt adhesive, olefinic hot melt adhesive using polyolefin copolymer, ethylene main chain copolymer (ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene- Examples thereof include hot-melt adhesives using methyl methacrylate copolymer (EMMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-n-butyl copolymer (EnBA), and the like. Of these, a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound and a styrenic block copolymer comprising a hydrogenated product thereof, because the stretchable composite material in which the nonwoven fabric and the polyurethane elastic fiber are bonded together is excellent in touch. It is preferable to use a rubber-based hot-melt adhesive made of

  Specific examples of a styrene block copolymer comprising a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound and a hydrogenated product thereof include styrene-isoprene-styrene block copolymer (SIS), and styrene. -Unhydrogenated block copolymer such as butadiene-styrene block copolymer (SBS); styrene-butadiene / butylene-styrene block copolymer (SBBS), styrene-ethylene / butylene-styrene block copolymer ( SEBS), hydrogenated products such as styrene-ethylene / propylene-styrene block copolymer (SEPS), and styrene-ethylene-ethylene / propylene-styrene block copolymer (SEEPS). These styrenic block copolymers may be used alone or in combination of two or more.

(Coating method of hot melt adhesive)
The hot melt adhesive is heated and melted in a heating and melting tank before being applied to various adherends. As a method for applying the hot melt adhesive melted by heating, there are a contact coating method and a non-contact coating method. Examples of the contact coating method include a method of directly applying a hot melt adhesive melted by heating to a substrate, such as slot coater coating, roll coater coating, and control seam coating. Non-contact coating methods include spiral coating, omega coating, curtain spray coating, etc., where the sprayer is installed at a position away from the substrate and heated to the hot melt adhesive discharged from the sprayer. A method of applying a hot melt adhesive while spraying the air with a predetermined pressure. Especially, since the application quantity of a hot-melt-adhesive agent required in order to express moderate adhesiveness becomes comparatively small, and the touch of an expansion-contraction composite material is excellent, it is preferable to use a non-contact coating method. When the non-contact coating method is used, since the hot melt adhesive is applied to the substrate in a fibrous form, the touch of the stretchable composite material joined by the hot melt adhesive is also improved.

  When the hot melt adhesive is applied to the substrate in a fibrous form, the hot melt adhesive is applied in a dispersed state within a certain area on the substrate, so that the stretchable composite material feels good. The degree of dispersion of the applied hot melt adhesive can be represented by variation in the amount of hot melt adhesive applied per unit area. The variation in the amount of hot melt adhesive applied per unit area is determined by cutting several 1 cm × 1 cm test pieces from the stretchable composite material joined by the hot melt adhesive and applying the hot melt adhesive amount to each test piece. Can be evaluated by calculating the standard deviation of the coating amount in the number of cut out test pieces. From the viewpoint of realizing a good touch while maintaining the creep performance, the dispersion degree of the hot melt adhesive is preferably 0.01 or more and 50 or less, more preferably 0.05 or more and 40 or less, and 0.1 or more and 30 or less. Is particularly preferred.

In the stretchable composite material according to the present embodiment, the application amount of the hot melt adhesive is preferably 3 g / m ² or more and 10 g / m ² or less, more preferably 4 g / m ² or more and 8 g / m ² or less. When the application amount of the hot melt adhesive is 3 g / m ² or more, the creep performance of the hot melt adhesive is improved, and the polyurethane elastic fiber disposed between the nonwoven fabrics is preferably joined to the nonwoven fabric. The polyurethane elastic fiber is not peeled off from the nonwoven fabric when the material is used or stored. When the application amount of the hot melt adhesive is 10 g / m ² or less, suitable creep performance can be realized without impairing the touch of the stretchable composite material.

  The melt viscosity of the hot melt adhesive used for producing the stretchable composite material according to this embodiment is preferably 1,000 mPa · s or more and 30,000 mPa · s or less at 160 ° C., and is preferably 3,000 mPa · s or more and 15,000 mPa · s. S or less is more preferable. When the melt viscosity of the hot melt adhesive at 160 ° C. is 1,000 mPa · s or more, the creep performance of the hot melt adhesive is improved, and the polyurethane elastic fiber is not peeled off from the nonwoven fabric. When the melt viscosity of the hot melt adhesive at 160 ° C. is 30,000 mPa · s or less, suitable creep performance can be realized without impairing the touch of the stretchable composite material.

  The melt viscosity at 160 ° C. of the hot melt adhesive in the present invention can be measured using various viscometers, for example, it can be measured using a Brookfield RVT viscometer. The spindle used at the time of measurement may be appropriately selected and used according to the melt viscosity of the hot melt adhesive. 4-27 can be used.

  EXAMPLES The present invention will be specifically described with reference to examples, but the present invention is not limited to only these examples. The measured values in Examples and the like are determined by the following measurement methods.

(1) Weight per unit area 10 square samples having a size of 10 cm along the direction of expansion and contraction of the stretchable composite material and 10 cm along the direction perpendicular thereto are measured and the mass is measured. It was calculated in terms of weight.

(2) Thickness Ten square test pieces having a size of 10 cm along the direction of expansion and contraction of the stretchable composite material and 10 cm along the direction orthogonal thereto are collected, and DG-257 type digital manufactured by Ozaki Mfg. Co., Ltd. Using a gauge and a SIS-7 type dial gauge stand, the thickness was measured with a 30 mmφ presser foot at a measurement pressure of 0.5 kPa, and the average value of 10 test pieces was obtained.

(3) Elongation elongation rate Ten rectangular test pieces having a length of 10 cm along the direction of expansion and contraction of the elastic composite material and 2.5 cm along the direction orthogonal thereto are sampled, and both ends in the direction of expansion and contraction in the natural state. Marking was performed with a marker pen at a position 2.5 cm from the part so that the distance between the marks was 5 cm. Next, this test piece was mounted on an RTG-type Tensilon universal material testing machine manufactured by Orientec Co., Ltd. with a distance between chucks of 5 cm so that the marked part of the test piece coincided with the distance between chucks. The stretchable composite material was stretched at a speed of 50 mm / min until the nonwoven fabric broke, and the distance L (mm) between chucks was measured. The stretch elongation rate was calculated according to the following formula (1), and the average value of 10 test pieces was obtained.
Stretch rate (%) = (L-50) / 50 × 100 (1)

(4) Gather pitch Ten rectangular test pieces having a length of 10 cm along the extension direction of the stretchable composite material and a length of 2.5 cm along the direction orthogonal thereto are sampled and formed on a cut surface along the extension direction. The number C (pieces) of convex portions having a wavy structure that can be observed was measured. The gather pitch was calculated according to the following formula (2), and the average value of 10 test pieces was obtained.
Gather pitch (mm) = 100 / C (2)

(5) Compression work, thickness change under compressive load Ten rectangular test pieces having a length of 10 cm along the extension direction and 2.5 cm along the direction orthogonal thereto are collected and compressed by Kato Tech. Using a test apparatus (KES-G5), a compression test was carried out under the following conditions, a compression work amount and a thickness change under a compression load were measured, and an average value of 10 test pieces was obtained.
Measurement conditions A test piece was placed on an elastic member having a hardness of 50, and a compression test was performed at a compression speed of 0.067 mm / sec using a metal plate having a pressure area of 2 cm ² . The change in thickness under compressive load was determined by the following formula.
Change in thickness under compressive load = T ₀ -T _{m In} formula, T ₀ : thickness of compressive load = 10 gf / cm ² , T _m : thickness of compressive load = 0.5 gf / cm ²

(6) Friction coefficient Ten rectangular test pieces having a length of 10 cm along the extension direction and a length of 2.5 cm along the direction perpendicular thereto are collected, and a friction test apparatus (KES-SE) manufactured by Kato Tech Co., Ltd. is used. The friction test in the extension direction was carried out, and the average value of 10 test pieces was obtained.

(7) Flexural rigidity of nonwoven fabric Ten specimens 10 cm wide and 30 cm long are arbitrarily sampled from a nonwoven fabric sample, placed on a flat table, and stainless steel so that it goes straight in the longitudinal direction at the center of the specimen. Place a ruler made of metal. The ruler preferably has a width of 2.5 cm and a measurement scale of 30 cm. Then, one end of the test piece is lifted up and slowly piled up in a state where a loop is formed without making a texture on the opposite test piece with a stainless ruler as a boundary. Next, slide the stainless steel ruler slowly in the direction perpendicular to the longitudinal direction in the direction of the loop generated by folding, and the end point is the state when the loop is extended by the repulsive force of the sample and there is no folding. Read the distance (L) between the edge of the specimen and the ruler on a scale. It represents with the average value of n = 10 of the front and back vertical direction and the horizontal direction. A shorter one indicates more flexibility.

(8) Creep performance The stretchable composite material is stretched to the fully stretched state along the stretch direction and fixed in that state. A cut is made in the polyurethane elastic fiber so as to have a width of 25 cm along the stretch direction of the polyurethane elastic fiber. The stretchable composite material with the cuts is fixed and placed in a constant temperature bath at 40 ° C. and left to stand for 2 hours. After 2 hours, the end of the polyurethane elastic fiber was marked, and the distance from the cut portion to the end of the polyurethane elastic fiber was measured to determine the creep performance. The shorter the distance from the cut portion to the polyurethane elastic fiber end, the better the creep performance.

[Example 1]
(1) Nonwoven fabric Polypropylene resin having a melt flow rate (MFR) of 60 g / 10 min (measured at a temperature of 230 ° C. and a load of 2.16 kg according to JIS-K7210) by a spunbond method, nozzle diameter 0.4 mm, single hole The filament group was extruded toward the moving collection surface at a discharge rate of 0.56 g / min · Hole and a spinning temperature of 255 ° C. to obtain a long fiber web (spinning speed 5000 m / min, average single yarn fineness 1.1 dtex).
Next, the obtained web was flat roll and emboss roll at a temperature of 138 ° C. and a linear pressure of 35 kgf / cm (pattern specifications: diameter 0.425 mm circular, staggered arrangement, horizontal pitch 2.1 mm, vertical pitch 1.1 mm, pressure bonding rate) 6.3%), the fibers were thermally bonded to each other to obtain a long fiber nonwoven fabric having a basis weight of 17 g / m ² .
The obtained long fiber nonwoven fabric was once wound around a paper tube and then slitted to a width of 300 mm to produce two nonwoven fabric wound bodies.

(2) Polyurethane elastic fiber By stirring 2,000 parts by weight of polyoxytetramethylene glycol having a number average molecular weight of 2,000 and 388 parts by weight of 4,4′-diphenylmethane diisocyanate at 60 ° C. for 3 hours under a dry nitrogen atmosphere. By reacting, a urethane prepolymer having a terminal isocyanate was obtained. After cooling this to room temperature, 2919 parts by weight of N, N-dimethylacetamide was added and stirred at room temperature to obtain a uniform prepolymer solution.
A solution prepared by dissolving 30.64 parts by weight of ethylenediamine as a chain extender, 5.87 parts by weight of diethylamine as a terminal terminator, and 2,739 parts by weight of N, N-dimethylacetamide is added to the prepolymer solution under high-speed stirring. In addition, it was further reacted at room temperature for 1 hour to obtain a 3,500 poise polyurethane solution at 30 ° C.
To this polyurethane solution, a condensate of p-cresol, dicyclopentadiene and isobutylene as an additive was added in an amount of 1% by weight based on the polyurethane polymer solid content, and 2- [2-hydroxy-3,5-bis (α, α-dimethyl). Benzyl) phenyl] -2H-benzotriazole was added in an amount of 0.2% by weight based on the polyurethane polymer solid content, and hydrotalcite was added in an amount of 0.3% by weight based on the polyurethane polymer solid content to obtain a uniform solution. The polyurethane solution to which the additive was added was defoamed at room temperature under reduced pressure to obtain a 3,000 poise spinning stock solution.

This spinning dope is discharged into an atmosphere of a heated nitrogen gas temperature of 270 ° C. directly below the spinneret using a spinneret 8 hole, and wound under the condition of a draft 1.15 between the goded roller and the take-up bobbin. An oil agent mainly composed of dimethyl silicon was applied at a take-up speed of 680 m / min, and then wound around a bobbin to obtain an 80 dtex polyurethane elastic fiber.
A polyurethane elastic yarn beam winding body in which 150 bobbins of polyurethane elastic fibers obtained in this way are sent out, arranged in a roller shape and unwound at the same speed, and 150 polyurethane elastic yarns are evenly arranged in parallel at a width of 175 mm. Was made. At this time, the polyurethane elastic yarn is wound at a stretch rate of 2.0 times by setting the unwinding speed of the polyurethane elastic yarn to 100 m / min and the winding speed of the polyurethane elastic yarn beam winding body to 200 m / min. I took it.

(3) Stretchable composite material 150 polyurethane elastic fibers were unwound and supplied from a polyurethane elastic fiber beam winder so that the yarn speed was 66.7 m / min. The two nonwoven fabric wound bodies were unwound and supplied so that the linear velocity of the nonwoven fabric was 100 m / min. Before placing the polyurethane elastic fiber between the two non-woven fabrics, the polyurethane elastic fibers separated by the yarn dividing guide are arranged so as to be arranged in parallel at intervals of 2 mm between the two supplied non-woven fabrics. In addition, after applying the rubber-based hot melt adhesive to the polyurethane elastic fiber and one nonwoven fabric at a coating amount of 5 g / m ² by the curtain spray method, the polyurethane elastic fiber and the nonwoven fabric are sandwiched between the other nonwoven fabric. Then, the nonwoven fabric and the polyurethane elastic fiber were joined by passing through an intermediate roller having a peripheral speed of 100 m / min and then passing between nip rolls having a linear pressure of 5 kgf / cm and a peripheral speed of 100 m / min. The nonwoven fabric bonded with polyurethane elastic fiber was wound around a paper tube at 100 m / min. The nonwoven fabric bonded with polyurethane elastic fiber was wound around a paper tube at 100 m / min.

When the nonwoven fabric and the polyurethane elastic fiber are joined, the polyurethane elastic fiber is supplied at 66.7 m / min, and is wound up by an intermediate roller and a nip roll at 100 m / min. . As a result, the polyurethane elastic fibers are stretched at an elongation rate of 2.0 times when producing the beam winder and at an elongation rate of 1.5 times when bonded to the nonwoven fabric, so that one by one in the spinning process. From the yarn length (initial length) when wound on the bobbin, the yarn is joined between the two nonwoven fabrics while being stretched 3.0 times.
When a nonwoven fabric bonded with polyurethane elastic fiber is unwound from a paper tube, the elastic elastic fiber stretched 3.0 times develops a fine gather-like structure on the nonwoven fabric and expands and contracts in one direction. Material was obtained. The stretchable material is left in a room at a temperature of 20 ° C. and a humidity of 65% RH for 48 hours, and the basis weight, thickness, stretch elongation rate, compression work, thickness change under compression load, bending stiffness of the nonwoven fabric, and coefficient of friction are measured. The results shown in Table 1 below were obtained. The creep performance evaluation results are also shown in Table 1.

[Example 2]
(1) Nonwoven fabric Mixed with polypropylene resin with an MFR of 33 g / 10 min. Octadecanoic acid glycerides (hydrogenated vegetable oils and fats) having a melting point of 86 to 90 ° C. (average melting point of 88 ° C.) to a pure content of 1.25% by weight. Further, a polypropylene elastomer, which is a low melting point polypropylene resin having a melting point of 104 ° C. and an MFR of 18 g / 10 min, is mixed so as to be 20% by weight. The filament group was extruded toward the moving collection surface at a spinning temperature of 0.56 g / min and a spinning temperature of 255 ° C. to obtain a long fiber web (spinning speed of 5,000 m / min, average single yarn fineness of 1.1 dtex).
Next, the obtained web was flat roll and emboss roll at a temperature of 138 ° C. and a linear pressure of 35 kgf / cm (pattern specifications: diameter 0.425 mm circular, staggered arrangement, horizontal pitch 2.1 mm, vertical pitch 1.1 mm, pressure bonding rate) 6.3%), the fibers were thermally bonded to each other to obtain a long fiber nonwoven fabric having a basis weight of 17 g / m ² .
The obtained long fiber nonwoven fabric was once wound around a paper tube and then slitted to a width of 300 mm to produce two nonwoven fabric wound bodies.
A stretchable composite member was produced in the same manner as in Example 1 except that the nonwoven fabric was changed to the nonwoven fabric of (2) in Example 2. The measurement results and creep performance evaluation results are shown in Table 1 below as in Example 1.

[Comparative Example 1]
An elastic composite material was produced in the same manner as in Example 1 except that the average single yarn fineness of the nonwoven fabric of Example 1 was 3.1 dtex, and the same measurement and creep performance evaluation as in Example 1 were performed. The results are shown in Table 1 below.

[Example 3]
A stretchable composite material was prepared in the same manner as in Example 1 except that the amount of the rubber-based hot melt adhesive applied was 3 g / m ^2, and the same measurement and creep performance evaluation as in Example 1 were performed. The results are shown in Table 1 below.

[Example 4]
A stretchable composite material was prepared in the same manner as in Example 1 except that the amount of the rubber-based hot melt adhesive applied was 10 g / m ^2, and the same measurement and creep performance evaluation as in Example 1 were performed. The results are shown in Table 1 below.

[Example 5]
From the polyurethane elastic fiber beam winder, 150 polyurethane elastic fibers were unwound and supplied so that the yarn speed was 66.7 m / min. The two nonwoven fabric wound bodies were unwound and supplied so that the linear velocity of the nonwoven fabric was 100 m / min. Before placing the polyurethane elastic fiber between the two non-woven fabrics, the polyurethane elastic fibers separated by the yarn dividing guide are arranged so as to be arranged in parallel at intervals of 2 mm between the two supplied non-woven fabrics. In addition, after applying the rubber-based hot melt adhesive to the nonwoven fabric at a coating amount of 5 g / m ² by slot coater coating, the nonwoven fabric is sandwiched between the polyurethane elastic fiber and the other nonwoven fabric so that the peripheral speed is 100 m / min. The nonwoven fabric and the polyurethane elastic fiber were joined by passing through an intermediate roller and then passing between nip rolls with a linear pressure of 5 kgf / cm and a peripheral speed of 100 m / min. The nonwoven fabric bonded with polyurethane elastic fiber was wound around a paper tube at 100 m / min. The nonwoven fabric bonded with polyurethane elastic fiber was wound around a paper tube at 100 m / min.
The obtained stretchable composite material was subjected to the same measurement and creep performance evaluation as in Example 1. The results are shown in Table 1 below.

  The stretch composite material according to the present invention realizes thinness and lightness that does not resonate with the outer when worn, in addition to good fit performance to the body and anti-slip performance, soft and soft touch and low skin irritation Therefore, it can be suitably used for sanitary materials such as paper diapers.

Claims (4)

A stretchable composite material that has a gather-like concavo-convex structure formed perpendicular to the extension direction, and is stretched in at least one direction, obtained by arranging a plurality of polyurethane elastic fibers between a pair of nonwoven fabrics and joining them with a hot melt adhesive Wherein the elastic composite material has a basis weight of 50 g / m ² or more and 200 g / m ² or less, a thickness of 0.5 mm or more and 5 mm or less, and an elongation to elongation ratio of 50% or more and 300% or less. .   The stretchable composite material according to claim 1, wherein a pitch of the gather-like uneven structure is 0.5 mm or more and 10 mm or less.   The stretchable composite material according to claim 1 or 2, wherein the compression work in the thickness direction is 0.20 gf · cm / cm or more, and the thickness change under a compression load is 0.5 mm or more.   The stretchable composite material according to any one of claims 1 to 3, wherein a friction coefficient when rubbing in the extending direction is 0.1 or more and 0.8 or less.