JP6751284B2 - Stretchable composite material with good feel - Google Patents

Description

TECHNICAL FIELD The present invention relates to a stretchable composite material that is thin, soft, and has a good texture. More specifically, the present invention relates to a stretchable composite material which is excellent in aesthetic appearance, is soft and has a good feel to the touch, and is excellent in fit, and is suitable for the abdomen gather portion of a disposable diaper.

In sanitary materials such as disposable diapers, gather-like stretchable materials are used for the abdomen, waist, legs and the like. As the performance required for this elastic material, it is necessary to have an elastic property that fits well to the body when worn and maintains a proper range of pressure without displacement or excessive tightening. In addition, since it comes into direct contact with the skin at an appropriate range of pressure, the elastic material is required to be thin and soft, have good texture, and have low irritation to the skin. Furthermore, in recent years, in so-called adult paper diapers for light incontinence, it is often the case that the wearer wears outerwear such as trousers and skirts while wearing the diaper as underwear, and it does not slip easily during activity, and It is required that the worn diaper is not conspicuous over the outerwear, and the elastic material used for these diapers is required to have both unprecedented thinness and slip-prevention prevention performance as well as aesthetic appearance. It is like this.

Various studies have been conducted so far as a method for obtaining a stretchable material.
Patent Document 1 below discloses a composite having a fine folding structure, which is obtained by stretching a composite composed of a composite spunbonded nonwoven fabric and a stretchable layer.
Further, Patent Document 2 below discloses a method for manufacturing a stretchable sheet by gear-drawing a nonwoven fabric composed of stretchable fibers and stretchable fibers.
Further, Patent Document 3 below discloses a stretchable nonwoven fabric in which elastic fibers are attached to one surface of a layer containing elastic fibers.
However, in these stretchable materials, a fiber component that does not stretch is stretched mainly by stretching the nonwoven fabric, and since it is a technology that expresses stretchability by kickback of the stretchable fiber component, naturally stretchable material There was a limit to the elongation rate, and it was not possible to satisfy the sufficient fitting performance and slip-off prevention performance.

On the other hand, in Patent Document 4 below, manufacturing 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 threads between the nonwoven fabrics is preferable from the viewpoint of satisfying sufficient fitting performance and slip-off prevention performance. However, by inserting and fixing a large number of elastic threads, an excessive tightening force is expressed, and in addition, the uneven undulations of the gathered part may become excessive and the irritation to the skin may be strengthened. It was not always satisfactory from the viewpoints of good touch and low irritation to the skin.

Further, 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 the elastic yarn is compositely integrated with the elastic yarn, the melted portion needs to be increased in order to obtain a sufficient joining force, resulting in a hard texture and a gathered portion. The uneven ridges on the surface were large and the texture was bad. Furthermore, if the number of thermocompression-bonded portions is reduced to give a soft texture, the elastic yarn is not sufficiently adhered and the elastic yarn and the non-woven fabric are peeled off, and a sufficient elastic material cannot be obtained.

JP, 2011-231444, A Patent No. 5238158 JP 2012-132115 A JP, 2005-320636, A Japanese Patent No. 2892106 JP-A-5-155841

The problems to be solved by the present invention include a good fit performance to the body and a slip-prevention performance, a soft and comfortable touch and a low irritation to the skin, and a thinness and a lightness that does not easily resonate to the outerwear when worn. It is an object of the present invention to provide an elastic member that can be suitably used in a paper diaper to be realized.

Furthermore, in addition to solving the above problems, there is provided a stretchable member that does not separate the elastic yarn from the nonwoven fabric during use or storage of a diaper.

As a result of intensive studies and experiments to solve the above problems, the present inventors have specified the rigidity of the nonwoven fabric, the method for inserting the polyurethane elastic yarn, and the joining method in the elastic member in which the nonwoven fabric and the polyurethane elastic fiber are joined. In addition to a good fit performance to the body and slip-prevention performance, soft and comfortable touch and low irritation to the skin, thinness and lightness that does not resonate with the outerwear when worn are realized. The present invention has been completed and 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 perpendicular to the stretching direction, obtained by joining with a hot melt adhesive. A stretchable composite material, having 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 a stretch-cut elongation ratio of 50% or more and 300% or less. Stretchable composite material.
[2] The stretchable composite material according to [1], wherein the gather-like concavo-convex structure has a pitch of 0.5 mm or more and 10 mm or less.
[3] Expansion and contraction according to the above [1] or [2], wherein the work of compression in the thickness direction is 0.20 gf·cm/cm or more, and the change in thickness under a compressive load is 0.5 mm or more. Composite material.
[4] The stretchable composite material according to any one of the above [1] to [3], which has a friction coefficient of 0.1 or more and 0.8 or less when rubbed in the stretching direction.

Furthermore, the inventors of the present invention apply a hot melt adhesive in a fibrous form when joining a plurality of polyurethane elastic fibers between nonwoven fabrics, so that good fit performance to the body and anti-slipping performance, softness and softness are achieved. It has been found that in addition to the performance that is good to the touch and has low irritation to the skin, it is possible to realize not only the thinness and lightness that does not easily resonate to the outerwear when worn, but also the creep performance of an elastic member suitable for use in a disposable diaper.

According to the present invention, in addition to a good fit performance to the body and a slip-prevention performance, a soft and comfortable touch and a low irritation to the skin, it is suitable for a paper diaper that has a thinness and lightness that does not easily resonate with the outerwear when worn. It is possible to provide an elastic member that can be used for.

(Method of combining non-woven fabric and polyurethane elastic fiber)
The stretchable composite material of the present embodiment is a stretchable material in which a nonwoven fabric and polyurethane elastic fibers are joined and which stretches in one direction. As the form of joining the nonwoven fabric and the polyurethane elastic fiber, for example, one side of one nonwoven fabric may be joined with the polyurethane elastic fiber, and then may be joined with the nonwoven fabric, after the polyurethane elastic fiber is joined to both sides of one nonwoven fabric, It may be one in which another non-woven fabric is joined to the surface facing each non-woven fabric, or one in which polyurethane elastic fibers are inserted between two non-woven fabrics and joined. 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 by using a hot melt adhesive, or a method of melting a part or all of the nonwoven fabric and/or the polyurethane elastic fiber by heat and joining The nonwoven fabric and the polyurethane elastic fiber can be bonded by the method. Of these, joining using a hot melt adhesive is preferable from the viewpoint of the softness of the stretchable composite material.
The non-woven fabric and the polyurethane elastic fiber may be continuously joined in the longitudinal direction of the polyurethane elastic fiber, or may be partially joined intermittently in the longitudinal direction of the polyurethane elastic fiber. Materials other than the non-woven fabric and the polyurethane elastic fiber may be inserted, attached, or coated as long as the object of the present invention is not impaired.

(Method of developing stretchable structure)
There is no particular limitation on the method of joining the nonwoven fabric and the polyurethane elastic fiber to form the stretchable composite material, and a conventionally known method can be applied. For example, a method may be used in which a stretchable composite material is obtained by expressing a gather-like structure by loosening the stretch of the polyurethane elastic fiber after joining the stretched polyurethane elastic fiber with the nonwoven fabric, or joining the nonwoven fabric and the polyurethane elastic fiber. After that, a method may be used in which the gather-like structure is developed by stretching the non-woven fabric after stretching at a meshing portion between two rolls having different speeds or between rolls on a gear having irregularities.

(Physical properties of stretchable composite material)
The stretchable composite material needs to have a basis weight of 50 g/m ² or more and 200 g/m ² or less. When the basis weight is 50 g/m ² or more, it has sufficient strength as a stretchable material used for sanitary materials, and when the basis weight is 200 g/m ² or less, it satisfies the lightness when used as sanitary materials. can do. From the viewpoint of a sufficient balance between strength and lightness when used as a sanitary material or the like, the basis weight is preferably 80 g/m ² or more and 150 g/m ² or less.
Further, the elastic 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.
Further, the stretchable composite material needs to have a "extended extension ratio" of 50% or more and 300% or less when stretched from a non-tensed state (relaxed state) until the nonwoven fabric breaks. If the extension cut extension rate is 50% or more, good fit performance to the body can be satisfied, and if the extension cut extension rate is 300% or less, the slip-off prevention performance is satisfied when used for sanitary materials. be able to.

(How to arrange polyurethane elastic fibers)
For a stretchable composite material in which polyurethane elastic fibers are joined to a nonwoven fabric, it is preferable to simultaneously bond two or more polyurethane elastic fibers to the nonwoven fabric. At this time, the polyurethane elastic fibers may be bonded to the nonwoven fabric in a state of being arranged in parallel, may be arranged in an arc shape, a parabolic shape, a zigzag shape, a sine wave shape, or the like, or may be arranged in combination. May be. In order to reduce the pitch of the gather-like structure of the stretchable composite material so that the stretchable material has a good feel and a low skin irritation, it is preferable to bond the polyurethane elastic fibers to the nonwoven fabric in a state of being arranged in parallel. ..
When two or more polyurethane elastic fibers are arranged and joined to the nonwoven fabric, the polyurethane elastic fibers can be arranged at arbitrary intervals. From the viewpoint 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 5 mm or less, and further preferably 2 mm or less. preferable. The polyurethane elastic fiber can be bonded to the non-woven fabric in a state where it is stretched at an arbitrary stretching rate as required.

(Type 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 constituent unit (hereinafter referred to as a polyurethane-based polymer).
The polyurethane-based polymer is, for example, a chain extension having a polyfunctional active hydrogen atom after synthesizing a urethane intermediate polymer which becomes a soft segment by reacting a polymer glycol having a number average molecular weight of 600 to 5,000 with an organic diisocyanate. It can be produced by using a known technique in which a hard segment is polymerized with an agent and the end is blocked with an end terminating agent having a monofunctional active hydrogen atom. When a low molecular weight diol is used as the chain extender, a polyurethane polymer in which the hard segment has a urethane bond is obtained, and when a bifunctional amine is used, a polyurethane urea polymer in which the hard segment has 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 kinds of oxyalkylene having 2 to 6 carbon atoms. One or more dibasic acids such as copolymerized polyether diol, adipic acid, sebacic acid, maleic acid, itaconic acid, azelaic acid and malonic acid, 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 Polylactone diol such as polyester diol, polyester amide diol, polyester ether diol, poly-ε-caprolactone diol and polyvalerolactone diol obtained from one or more glycols such as cyclohexane and 1,4-dimethylol cyclohexane , Polycarbonate diol, polyacryl diol, polythioether diol, polythioester diol, or copolymers and mixtures of these diols. In order for the stretchable composite material to have sufficient fit performance and slip-off prevention performance, the polymer glycol may be polyoxytetramethylene glycol or polyoxytetramethylene glycol having a different number of carbon atoms, preferably a branched alkylene group. Copolymerized polyether diols in which glycols with are copolymerized are 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, [isopropylidene bis(p-phenylene)] Diisocyanate, diphenyl ether-4,4'-diisocyanate, 1,5-naphthalene diisocyanate, 1,6-hexamethylene diisocyanate, methylenebis(4-cyclohexyl-4,1-phenylene) diisocyanate, 1,3- and 1,4-cyclohexene Examples include cilendiisocyanate, propylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and mixtures thereof.

Examples of the chain extender having a polyfunctional active hydrogen atom include hydrazine, polyhydrazine, and 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, for example, 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 cyclohexane, 1,4-dimethylol cyclohexane, etc. can be used. Preferred are ethylenediamine and 1,2-propylenediamine.

As the terminal terminator having a monofunctional active hydrogen atom, for example, a dialkylamine such as diethylamine, or an alkyl alcohol such as ethanol is used. These chain extenders or terminal terminators may be used alone or in admixture of two or more.
This polyurethane-based polymer includes other compounds usually used for polyurethane elastic fibers, for example, ultraviolet absorbers, antioxidants, light stabilizers, chlorine embrittlement resistance agents, gas resistance stabilizers, colorants, matting agents. A filler and the like may be added.

The polyurethane polymer thus obtained can be molded into a fibrous shape by known dry spinning, wet spinning, melt spinning or the like to produce a polyurethane elastic fiber. The polyurethane elastic fiber may be a monofilament or a multifilament, and one filament constituting the multifilament may be composed of a single polyurethane-based polymer or may be composed of two or more kinds of polyurethane-based polymers. May be. At this time, two or more kinds of polyurethane polymers may be completely mixed and spun into polyurethane elastic yarns, or one filament composed of one polyurethane polymer may be coated with another polyurethane polymer. It may be 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.

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 satisfy both the performance of fitting to the body and preventing slipping and softness.
The obtained polyurethane elastic fiber, polydimethylsiloxane, polyester-modified silicone, polyether-modified silicone, amino-modified silicone, mineral oil, mineral fine particles, for example, silica, colloidal alumina, talc, higher fatty acid metal salt powder, for example, Oil agents such as solid waxes at room temperature such as magnesium stearate, calcium stearate and the like, higher aliphatic carboxylic acids, higher aliphatic alcohols, paraffin, polyethylene and the like may be applied alone or in any combination as required.

(Nonwoven fabric)
The type of nonwoven fabric used for the stretchable composite material of the present embodiment is not particularly limited, and long-fiber nonwoven fabric such as spunbonded nonwoven fabric, meltblown nonwoven fabric, flash spinning nonwoven fabric, electrostatic spinning nonwoven fabric, wet spinning nonwoven fabric, etc. Or a short fiber nonwoven fabric obtained by a wet papermaking method.
Although there is no limitation on the basis weight of the nonwoven fabric, in order to obtain a stretchable nonwoven fabric member having a basis weight of 50 g/m ² or more and 200 g/m ² or less, for example, when polyurethane elastic fibers are bonded to both surfaces of one nonwoven fabric, When the polyurethane elastic fiber is bonded to one surface of one nonwoven fabric, the weight of the nonwoven fabric is preferably 20 g/m ² or more and 100 g/m ² or less, and the polyurethane elastic fiber is bonded between the two nonwoven fabrics. In this case, the weight of one nonwoven fabric is preferably 10 to 50 g/m ² or less.

The fibers constituting the non-woven fabric are not particularly limited, and may be polyolefin fibers such as polyethylene and polypropylene, polyester fibers, polyamide fibers, cellulose fibers, polyurethane fibers, or a mixture thereof. You may use the nonwoven fabric which consists of a different fiber in combination of 2 or more types. As the non-woven fabric used for the stretchable material that is preferably used as the sanitary material, a polyolefin long-fiber non-woven fabric is preferable. As the polyolefin fibers constituting the polyolefin long-fiber non-woven fabric, for example, fibers made of resin such as polyethylene, polypropylene, copolymers of those monomers and other α-olefins, and the like can be used. Of these, polypropylene-based fibers made of polypropylene or a polypropylene copolymer are preferably used because they have high strength, are not easily broken, and have excellent dimensional stability when producing a stretchable material.

In order for the stretchable composite material to have good flexibility, it is preferable that the nonwoven fabric used 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 the joining means when joining the long fibers into a nonwoven fabric, and the partial thermocompression bonding area ratio is preferably small. Further, the smaller the average single-filament fineness of the polyolefin filaments constituting the non-woven fabric, the higher the flexibility, but at the same time, it causes the deterioration of the spinning stability. Therefore, the average single-filament fineness is 0.5 dtex or more and 3.0 dtex or less. It is preferably 0.7 dtex or more and 2.0 dtex or less, more preferably 0.7 dtex or more and 1.4 dtex or less. In order to obtain good flexibility, the polyolefin long-fiber nonwoven fabric may be processed to have irregularities. As the shape of the shaping process, a straight line, a curved line, a corner, a circle, a satin-like shape, or other continuous or discontinuous shape can be applied, but from the viewpoint of the flexibility effect, the hexagonal pattern is preferable. Furthermore, in order to obtain good flexibility, an ester compound of a trivalent to hexavalent polyol and a monocarboxylic acid may be added to the polyolefin long-fiber nonwoven fabric. The ester compound may be mixed with a polyolefin resin and then spun to obtain a polyolefin long fiber nonwoven fabric, or the ester compound may be applied after obtaining a polyolefin long fiber nonwoven fabric.

The non-woven fabric used for the stretchable composite material may be provided with a hydrophilizing agent. Further, the fibers constituting the non-woven fabric used for the stretchable composite material include a nucleating agent, a flame retardant, an inorganic filler, a pigment, a colorant, a heat stabilizer, an antistatic agent, etc. within a range not impairing the object of the present invention. It may be blended.
In the present invention, in order to achieve a stretchable material which is excellent in aesthetic appearance, soft and soft to the touch, and excellent in fit, the nonwoven fabric used is formed to follow the expansion and contraction of elastic fibers, gathered The shape of the uneven structure is important. Nonwoven fabric forms a gather-like concavo-convex structure due to the expansion and contraction of elastic fibers, but if the bending rigidity of the non-woven fabric is too great, the pitch of gathers becomes too large to follow the expansion and contraction of elastic fibers, and the thickness of the elastic material is thick, resulting in an uneven structure. Has a non-uniform shape and is inferior in aesthetic appearance. Furthermore, when it rubs, it has a rough texture, has a high coefficient of friction, and has a poor texture. In order to obtain the stretchable composite material of the present embodiment, the bending rigidity of the nonwoven fabric is 80 mm or less, preferably 70 mm or less, more preferably 60 mm or less. When the bending rigidity of the non-woven fabric is within the above range, the gather-like uneven structure follows the expansion and contraction of the elastic fiber to form a fine and uniform structure of 0.5 mm or more and 10 mm or less, and the touch is good and the appearance is aesthetic. Will be excellent.

In the stretchable composite material according to the present embodiment, which is soft and has a good feel to the touch, the softness when compressed by pressure is important. The softness when compressed is indicated by the amount of compression work in the thickness direction and the change in thickness under a compressive load. The work of compression is preferably 0.2 gf·cm/cm or more, and the change in thickness under a compression load is preferably 0.5 mm or more. The elastic composite material that is soft when compressed compresses the concavo-convex structure due to pressure and fits the body structure. As a result, the contact area between the skin and the stretchable material becomes large, which makes it difficult for the skin to slip off during activity without increasing the contact pressure, and it is smooth and has a good feel to the skin. Furthermore, it is thin and inconspicuous when worn, and has an excellent aesthetic appearance.
If the work of compression is less than 0.2 gf·cm/cm and the change in thickness under a compressive load is less than 0.5 mm, the uneven structure is less likely to be deformed by the applied pressure, and the touch becomes poor. In addition, the softness when worn is insufficient. On the other hand, the compression work is 3.0 gf·cm/cm or less from the viewpoint of the fitting property of the gather-shaped uneven structure, and the thickness change under a compressive load is said to be maintained even when the gather-shaped uneven structure is pressed. From the viewpoint, it is 5.0 mm or less. When the work of compression exceeds 3.0 gf·cm/cm, the gather-like concavo-convex structure becomes excessively bulky, and the fit property when worn becomes poor. Further, if the change in thickness under a compressive load exceeds 5.0 mm, the gathered shape is easily crushed by the pressure applied during wearing, and the softness that is plump is impaired. In addition, the uneven structure having a thickness change of more than 5.0 mm has an excessively large thickness when it is gathered, resulting in poor fit when worn and inferior aesthetic appearance.

In the stretchable composite material according to the present embodiment, in order to achieve a stretchable material having a good feel to the touch, it is preferable that the friction coefficient when being rubbed in the stretching direction is 0.1 or more and 0.8 or less. When the coefficient of friction is less than 0.1, slippage easily occurs during operation during wearing. Further, if the friction coefficient exceeds 0.8, the material has a rough texture.
Furthermore, in order to achieve a fit property as a stretchable composite material and a pressure in an appropriate range, the stress at 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, when it is joined as a stretchable material, the dimension is likely to change due to tension, which is not preferable. In addition, the gather-like concavo-convex structure causes the elastic composite material to become thin because the nonwoven fabric is too soft, and becomes hard during compression.

(Joining method)
From the viewpoint of softness, the stretchable composite material according to the present embodiment preferably joins the non-woven fabric and the polyurethane elastic fiber with a thermoplastic material, and more preferably with a hot melt adhesive. As a bonded state, the nonwoven fabric and the polyurethane elastic fiber may be bonded all over the surface 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. Materials other than the non-woven fabric and the polyurethane elastic fiber may be inserted, attached, or coated as long as the object of the present invention is not impaired.
In the hot-melt joining of the nonwoven fabric and the elastic fiber, if the joining is weak, the gather-like concavo-convex structure becomes non-uniform and the touch becomes poor.
Further, if the amount of the hot melt adhesive is too large, the hot melt adhesive becomes stiff at the time of compression and the softness at the time of wearing becomes insufficient. Further, the adhesive penetrates into the non-woven fabric, and the non-woven fabric becomes flexurally stiff, and the pitch of the gather-like concavo-convex structure is large, resulting in poor texture. In addition, along with this, the fit to the skin is also hindered.

(Hot melt adhesive)
In this embodiment, it is preferable to use a hot melt adhesive containing a thermoplastic elastomer as a main component. As a hot melt adhesive containing a thermoplastic elastomer as a main component, a rubber-based hot copolymer obtained by using a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound and a styrene block copolymer composed of a hydrogenated product thereof. Melt adhesives, olefin hot melt adhesives using polyolefin copolymers, ethylene main chain copolymers (ethylene-vinyl acetate copolymer (EVA), ethylene-methyl acrylate copolymer (EMA), ethylene- Examples of the hot melt adhesive include a methyl methacrylate copolymer (EMMA), an ethylene-ethyl acrylate copolymer (EEA), and an ethylene-n-butyl copolymer (EnBA). Of these, since the stretch composite material in which the nonwoven fabric and the polyurethane elastic fiber are laminated has excellent touch, a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound and a styrene block copolymer comprising the hydrogenated product thereof. It is preferable to use a rubber-based hot melt adhesive obtained by using.

As a styrene block copolymer composed of a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene compound and a hydrogenated product thereof, specifically, styrene-isoprene-styrene block copolymer (SIS), and styrene -Unhydrogenated block copolymers such as butadiene-styrene block copolymer (SBS); styrene-butadiene/butylene-styrene block copolymer (SBBS), styrene-ethylene/butylene-styrene block copolymer ( SEBS), styrene-ethylene/propylene-styrene block copolymer (SEPS), styrene-ethylene-ethylene/propylene-styrene block copolymer (SEEPS), and other hydrogenated products. These styrene 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 coating method of the hot melt adhesive which is heated and melted, 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 jetting machine is installed at a position away from the base material, and the hot melt adhesive discharged from the jetting machine is heated. A method of applying the hot melt adhesive while blowing the air at a predetermined pressure can be mentioned. Among them, it is preferable to use the non-contact coating method because the amount of the hot melt adhesive required for exhibiting appropriate adhesiveness is relatively small and the stretchable composite material is excellent in touch. When the non-contact coating method is used, since the hot melt adhesive is applied to the substrate in a fibrous form, the stretch composite material joined by the hot melt adhesive also has a good texture.

When the hot melt adhesive is applied to the base material in a fibrous form, the hot melt adhesive is applied in a dispersed state within a certain area on the base material, and thus the stretchable composite material has a good feel to the touch. The degree of dispersion of the applied hot melt adhesive can be represented by the variation in the amount of the hot melt adhesive applied per unit area. The variation in the amount of hot melt adhesive applied per unit area is determined by cutting out several 1 cm x 1 cm test pieces from the stretchable composite material bonded with the hot melt adhesive, and applying the amount of hot melt adhesive applied to each test piece. Can be evaluated by calculating the standard deviation of the coating amount of the number of cut out test pieces. From the viewpoint of achieving good touch while maintaining the creep performance, the degree of dispersion 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 preferable.

In the stretchable composite material according to the present embodiment, the coating amount of the hot melt adhesive is preferably 3 g/m ² or more and 10 g/m ² or less, and more preferably 4 g/m ² or more and 8 g/m ² or less. When the coating 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 fibers arranged between the nonwoven fabrics are preferably bonded to the nonwoven fabric, so that the stretchable composite of the present invention can be obtained. The polyurethane elastic fiber does not come off from the nonwoven fabric when the material is used or stored. When the coating amount of the hot melt adhesive is 10 g/m ² or less, suitable creep performance can be realized without impairing the feel of the stretchable composite material.

The melt viscosity of the hot melt adhesive used for producing the stretchable composite material according to the present embodiment is preferably 1,000 mPa·s or more and 30,000 mPa·s or less at 160° C., and 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 prevented from peeling 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 feel 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, 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.

The present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The measured values in Examples and the like are obtained by the following measuring methods.

(1) Basis weight 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 sampled and the mass is measured, and the average value per unit area is measured. It was calculated in terms of weight.

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

(3) Stretching/extending rate Ten rectangular test pieces having a length of 10 cm along the stretching direction of the stretchable composite material and 2.5 cm along the direction orthogonal to the stretched composite material were sampled, and both ends in the stretching direction in the natural state. A mark was made at a position 2.5 cm from the portion with a marker pen so that the mark interval was 5 cm. Next, this test piece was mounted on an RTG-type Tensilon universal material testing machine manufactured by Orientec Co., Ltd. in which the distance between chucks was set to 5 cm so that the marked portion of the test piece would match the distance between chucks, and the test was conducted. The stretchable composite material nonwoven fabric was stretched at a speed of 50 mm/min until it broke, at which time the chuck distance L (mm) was measured. The elongation percentage was calculated according to the following formula (1), and the average value of 10 test pieces was calculated.
Full stretch elongation 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 cut on the cut surface along the extension direction. The number C (pieces) of observable wavy structure protrusions 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) Change in compression work and thickness under compression load Ten rectangular test pieces having a length of 10 cm along the extension direction and 2.5 cm along the direction orthogonal to the extension direction were sampled and compressed by Kato Tech. A compression test was performed under the following conditions using a test apparatus (KES-G5), the work of compression and the change in thickness under compression load were measured, and the average value of 10 test pieces was obtained.
-Measurement condition A test piece was placed on an elastic member having a hardness of 50, and a compression test was performed at a compression rate 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 calculated by the following formula.
Thickness change under compressive load=T ₀ −T _{m in the} formula, T ₀ : compressive load=10 gf/cm ² thickness, T _m : compressive load=0.5 gf/cm ² thickness

(6) Friction coefficient Ten rectangular test pieces having a length of 10 cm along the extending direction and a length of 2.5 cm along the direction orthogonal to the extending direction were sampled, and a friction test device (KES-SE) manufactured by Kato Tech Co. was used. A friction test in the stretching direction was carried out using the test pieces, and the average value of 10 test pieces was obtained.

(7) Bending rigidity of non-woven fabric From a non-woven fabric sample, 10 pieces of 10 cm wide and 30 cm long test pieces were arbitrarily sampled, placed on a flat table, and made of stainless steel so as to go straight to the center of the test piece in the longitudinal direction. Put a ruler made of it. 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 the test piece on the opposite side with the ruler made of stainless steel as a boundary is slowly overlapped with a loop formed without a texture. Next, slowly slide the stainless steel ruler in the direction of the loop formed by folding it in a state orthogonal to the longitudinal direction, and make the end point the state when the loop stretches due to the repulsive force of the sample and the folding is lost. , Read the distance (L) between the edge of the test piece and the ruler on a scale. It is expressed by an average value of n=10 in the front and back vertical directions and the horizontal direction. Shorter ones are more flexible.

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

[Example 1]
(1) Nonwoven fabric A 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) is spun-bonded to have a nozzle diameter of 0.4 mm and a single hole. At a discharge rate of 0.56 g/min·Hole and a spinning temperature of 255° C., the filament group was extruded toward the moving collection surface to obtain a long fiber web (spinning speed 5000 m/min, average single yarn fineness 1.1 dtex).
Next, the obtained web is subjected to a flat roll and an embossing roll at a temperature of 138° C. and a linear pressure of 35 kgf/cm (pattern specifications: diameter 0.425 mm circle, zigzag arrangement, lateral pitch 2.1 mm, longitudinal pitch 1.1 mm, crimping rate). The fibers were heat-bonded to each other at 6.3%) to obtain a long-fiber nonwoven fabric having a basis weight of 17 g/m ² .
The obtained long-fiber non-woven fabric was once wound around a paper tube, and then slitted to have a width of 300 mm to produce two non-woven fabric rolls.

(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 under a dry nitrogen atmosphere at 60° C. for 3 hours. The reaction was performed to obtain a urethane prepolymer having an isocyanate terminal. 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 was added to the above prepolymer solution under high speed stirring. It was added all at once and further reacted at room temperature for 1 hour to obtain a polyurethane solution of 3,500 poise at 30°C.
To this polyurethane solution, a condensate of p-cresol, dicyclopentadiene and isobutylene was added as an additive in an amount of 1% by weight based on the solid content of the polyurethane polymer, 2-[2-hydroxy-3,5-bis(α,α-dimethyl). Benzyl)phenyl]-2H-benzotriazole was added to the polyurethane polymer solids in an amount of 0.2% by weight, and hydrotalcite was added to the polyurethane polymer in an amount of 0.3% by weight to form a uniform solution. The polyurethane solution containing the additives was degassed under reduced pressure at room temperature to obtain a spinning dope having a poise of 3,000 poise.

This spinning dope was discharged into an atmosphere of a heated nitrogen gas temperature of 270° C. immediately below the spinneret using an 8-hole spinneret and wound under the condition of a draft of 1.15 between the goded roller and the winding bobbin. An oil agent containing dimethylsilicon as a main component was applied at a take-up speed of 680 m/min, and then wound on a bobbin to obtain a polyurethane elastic fiber of 80 dtex.
A polyurethane elastic yarn beam winding body in which 150 bobbins of the polyurethane elastic fiber thus obtained are fed out, arranged in a roller shape and unwound at the same speed, and 150 polyurethane elastic yarns are evenly arranged in a width of 175 mm in parallel. Was produced. At this time, the unwinding speed of the polyurethane elastic yarn is set to 100 m/min, and the winding speed of the polyurethane elastic yarn beam winding body is set to 200 m/min. I took it.

(3) Stretchable composite material From the polyurethane elastic fiber beam winding body, 150 polyurethane elastic fibers were unwound and supplied so that the yarn speed was 66.7 m/min. The two non-woven fabric rolls were unwound and fed so that the non-woven fabric had a linear velocity of 100 m/min. Before the two elastic nonwoven fabrics are placed between the two nonwoven fabrics, the elastic polyurethane fibers divided by the thread dividing guide are arranged so as to be arranged in parallel with each other between the two supplied nonwoven fabrics, and the polyurethane elastic fibers are sandwiched between the two nonwoven fabrics. Then, after applying a rubber hot melt adhesive to the polyurethane elastic fiber and one of the nonwoven fabrics by a curtain spray method at a coating amount of 5 g/m ² , 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 between nip rolls having a linear pressure of 5 kgf/cm and a peripheral speed of 100 m/min. The nonwoven fabric to which the polyurethane elastic fiber was joined was wound around a paper tube at 100 m/min. The nonwoven fabric to which the polyurethane elastic fiber was joined was wound around a paper tube at 100 m/min.

When the non-woven fabric and the polyurethane elastic fiber were joined, the polyurethane elastic fiber was supplied at 66.7 m/min and was wound up by the intermediate roller and the nip roll at 100 m/min. .. As a result, the polyurethane elastic fiber is stretched at a stretch rate of 2.0 times when manufacturing the beam winding body and at a stretch 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, it means that the two nonwoven fabrics were joined in the state of being stretched 3.0 times.
When a nonwoven fabric with polyurethane elastic fibers joined is unwound from a paper tube, the shrinkage stress of the polyurethane elastic fibers stretched 3.0 times causes a minute gather-like structure to appear in the nonwoven fabric, and expands and contracts in one direction. The material was obtained. The stretchable material is allowed to stand in a room at a temperature of 20° C. and a humidity of 65% RH for 48 hours, and the weight per unit area, thickness, extension/extension ratio, compression work amount, thickness change under compression load, bending rigidity of the nonwoven fabric, and friction coefficient are measured. The results shown in Table 1 below were obtained. Table 1 also shows the creep performance evaluation results.

[Example 2]
(1) Nonwoven fabric A glyceride of octadecanoic acid (hydrogenated animal and vegetable oil) having a melting point of 86 to 90°C (average melting point of 88°C) is mixed with polypropylene resin having an MFR of 33 g/10 min so as to have a pure content of 1.25% by weight. Then, 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, and a spun bond method is used to form a spinneret diameter of 0.35 mm and a single hole discharge amount. The filament group was extruded toward the moving and collecting surface at 0.56 g/min at 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 is subjected to a flat roll and an embossing roll at a temperature of 138° C. and a linear pressure of 35 kgf/cm (pattern specifications: diameter 0.425 mm circle, zigzag arrangement, lateral pitch 2.1 mm, longitudinal pitch 1.1 mm, crimping rate). The fibers were heat-bonded to each other at 6.3%) to obtain a long-fiber nonwoven fabric having a basis weight of 17 g/m ² .
The obtained long-fiber non-woven fabric was once wound around a paper tube, and then slitted to have a width of 300 mm to produce two non-woven fabric rolls.
An elastic composite member was produced in the same manner as in Example 1 except that the non-woven fabric was the non-woven fabric of (1) of Example 2. The measurement results and the creep performance evaluation results are shown in Table 1 below as in Example 1.

[Comparative Example 1]
A stretchable 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 produced in the same manner as in Example 1 except that the coating amount of the rubber hot melt adhesive 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 produced in the same manner as in Example 1 except that the coating amount of the rubber hot melt adhesive was set to 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 (reference example) ]
From the polyurethane elastic fiber beam winding body, 150 polyurethane elastic fibers were unwound and supplied so that the yarn speed was 66.7 m/min. The two non-woven fabric rolls were unwound and fed so that the non-woven fabric had a linear velocity of 100 m/min. Before the two elastic nonwoven fabrics are placed between the two nonwoven fabrics, the elastic polyurethane fibers divided by the thread dividing guide are arranged so as to be arranged in parallel with each other between the two supplied nonwoven fabrics, and the polyurethane elastic fibers are sandwiched between the two nonwoven fabrics. After applying a rubber hot melt adhesive to the nonwoven fabric with 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, and the peripheral speed is 100 m/min. The nonwoven fabric and the polyurethane elastic fiber were bonded by passing through an intermediate roller and then between nip rolls having a linear pressure of 5 kgf/cm and a peripheral speed of 100 m/min. The nonwoven fabric to which the polyurethane elastic fiber was joined was wound around a paper tube at 100 m/min. The nonwoven fabric to which the polyurethane elastic fiber was joined was wound around a paper tube at 100 m/min.
The stretchable composite material thus obtained was subjected to the same measurement and creep performance evaluation as in Example 1. The results are shown in Table 1 below.

The stretchable composite material according to the present invention realizes a good fit performance to a body, a slip-prevention performance, a softness and a good feel to the skin and a low irritation to the skin. Therefore, it can be suitably used for sanitary materials such as disposable diapers.

Claims (2)

A plurality of polyurethane elastic fibers are arranged between a pair of nonwoven fabrics, and the polyurethane elastic fibers are joined to the nonwoven fabric by a hot melt adhesive in a stretched state, and gather-like irregularities formed perpendicular to the stretching direction. A stretchable composite material having a structure that stretches in at least one direction,
The basis weight of the stretchable composite material 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 elongation at elongation is 50% or more and 300% or less,
Using a compression tester, a test piece was placed on an elastic member having a hardness of 50, and a metal plate with a pressing area of 2 cm ² was used to perform a compression test at a compression rate of 0.067 mm/sec in the thickness direction. Compression work is 0.25 gf·cm/cm or more and 0.5 gf·cm/cm or less , and
In the compression test, the following formula:
Thickness change under compressive load = T ₀ -T _m
(In the formula, T ₀ : thickness at a compression load of 10 gf/cm ² , T _m : thickness at a compression load of 0.5 gf/cm ² )
The thickness change under the compressive load calculated by is 0.5 mm or more and 0.7 mm or less ,
The gather-like concavo-convex structure has a pitch of 0.5 mm or more and 5 mm or less,
The coating amount of the hot melt adhesive is 3 g/m ² or more and 10 g/m ² or less,
The stretchable composite material, wherein the nonwoven fabric has a bending rigidity of 80 mm or less and an average single yarn fineness of 2.0 dtex or less. The stretchable composite material according to claim 1, which has a friction coefficient of 0.1 or more and 0.8 or less when rubbed in the stretching direction.