JP3910172B2 - Composite sheet and manufacturing method thereof - Google Patents

Description

  The present invention relates to a composite sheet useful as a back material of an absorbent article such as a disposable diaper, and more particularly relates to a composite sheet that is excellent in texture and adhesive force and hardly causes blocking.

  A composite sheet obtained by bonding a liquid-impermeable sheet and a nonwoven fabric with an adhesive is widely used as a back material of absorbent articles such as disposable diapers. And when such a composite sheet is used for, for example, a disposable diaper, it is required that the texture such as softness is good, so that the nonwoven fabric and the liquid-impermeable sheet are thin. Is used. In the composite sheet, since it is required that the non-woven fabric and the liquid-impermeable sheet have high adhesive strength, it is usually necessary to use a large amount of adhesive or increase the wire diameter of the adhesive. Has been done.

  However, when such thin nonwoven fabric and liquid-impermeable sheet are used, if the amount of adhesive used is large or the coated adhesive has a large wire diameter, a thin material will be used. Even if it is used, the texture becomes worse due to the hardness of the adhesive, or the adhesive oozes on the surface of the nonwoven fabric and adheres to the adjacent composite sheet when the composite sheet is rolled up. (Blocking) has occurred.

  In short, the conventional composite sheet does not satisfy all of adhesive strength, texture and anti-blocking properties, and development of a composite sheet satisfying all of these has been demanded.

  An object of the present invention is to provide a composite sheet having excellent adhesive force, good texture, and no blocking, and a method for producing the composite sheet.

  As a result of intensive studies to solve the above problems, the present inventors have obtained a non-woven fabric having a specific basis weight composed of a liquid-impermeable sheet having a specific thickness and a constituent fiber having a specific fiber diameter. It has been found that a composite sheet obtained by applying a specific amount of a specific adhesive in a specific shape can achieve the above object.

The present invention has been made based on the above findings, and in a composite sheet obtained by bonding a liquid-impermeable sheet and a nonwoven fabric via an adhesive, the liquid-impermeable sheet has a thickness of 15 to 40 μm. The non-woven fabric is composed of constituent fibers having a fiber diameter of 1.5 to 3.5 denier, and has a basis weight of 15 to 35 g / m ^2. The adhesive is made of styrene elastomer, ethylene It is a hot-melt adhesive based on vinyl acetate copolymer or amorphous polyalphaolefin, and its melt viscosity is 10000 cps or less at 180 ° C. The fiber diameter of the adhesive is 15 to 210 μm, the coating amount of the adhesive is 0.5 to 7 g / m ² , and the length is 1 cm in a direction orthogonal to any one of the fibrous adhesives. line The number of adhesive intersects with 該線 when drawn is between 10 and 40 present, it is intended to provide a composite sheet according to claim.

The present invention also provides a composite sheet in which the liquid-impermeable sheet is a moisture-permeable sheet, and the moisture-permeable amount of the moisture-permeable sheet is 0.5 to 4 g / (100 cm ² · hr). is there.
The present invention also provides a composite sheet in which the composite sheet is heat embossed and the embossed area ratio is 40% or less with respect to the entire composite sheet.

  Furthermore, the present invention provides an adhesive coating process in which an adhesive is sprayed in a fiber form on the liquid-impermeable sheet or non-woven fabric as a preferable production method of the composite sheet, and this coating is performed. The manufacturing method of a composite sheet which comprises the bonding process which bonds a nonwoven fabric or a liquid-impermeable sheet | seat on the surface is provided.

The composite sheet of the present invention is excellent in adhesive strength, has a good texture, and does not cause blocking.
Moreover, according to the manufacturing method of the composite sheet of this invention, the composite sheet of this invention can be manufactured easily.

Hereinafter, the composite sheet of the present invention will be described in detail.
The composite sheet of the present invention specifies a liquid-impermeable sheet having a specific thickness and a non-woven fabric having a specific basis weight composed of constituent fibers having a specific fiber diameter, and an adhesive having a specific melt viscosity. It is characterized in that a specific amount is applied in the shape of

Said specific thickness which the said liquid-impermeable sheet used in this invention has is 15-40 micrometers, and it is still more preferable that it is 20-35 micrometers.
When the thickness is less than 15 μm, it becomes difficult to control the thickness at the time of manufacture, and it is easily broken when bonded to the nonwoven fabric and at the time of manufacturing the disposable diaper. On the other hand, when the thickness exceeds 40 μm, the texture such as softness and the touch in the composite sheet are lowered.

The liquid impervious sheet used in the present invention is not particularly limited as long as it has the above-mentioned thickness and liquid impermeability, and is a moisture permeable sheet such as a non-moisture permeable sheet and a porous sheet. Any of these can be used.
As the non-moisture permeable sheet, a general non-moisture permeable and liquid impervious film mainly composed of a polyolefin resin, mixed with a pigment and a filler, and formed into a film by a T-die molding machine or an inflation molding machine. Sex sheet. The moisture-impermeable sheet is preferably based on a polyethylene resin, and the basis weight is preferably 10 to 50 g / m ² .

  Since the moisture permeable sheet easily emits water vapor, it is particularly preferable when the composite sheet of the present invention is used for an absorbent article, a clothing material, or the like that easily feels stuffiness.

  As the moisture permeable sheet, for example, a porous sheet obtained by kneading a filler in a polyolefin resin and stretching or uniaxially or biaxially stretching a film or sheet obtained by melt molding is preferable. .

  As said polyolefin resin, what has a monoolefin polymer, such as ethylene, propylene, butene, etc., and the copolymer of these olefins as a main component is used, for example. Specific examples of the polyolefin resin include high density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, crystalline ethylene-propylene block copolymer, polybutene, ethylene-vinyl acetate copolymer, and mixtures thereof. Among these, linear low density polyethylene is desirable because it is flexible and tough.

As the filler, an inorganic filler and an organic filler are used.
Inorganic fillers include calcium carbonate, gypsum, talc, carbon black, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, calcium phosphate, aluminum hydroxide, zinc oxide, hydroxide Examples include magnesium, calcium oxide, magnesium oxide, titanium oxide, alumina, mica, asbestos powder, shirasu balloon, zeolite, silicate clay, cement, silica fume, and mica powder.
On the other hand, examples of the organic filler include wood powder, coal powder, and pulp powder. These fillers may be used alone or as a mixture.

The average particle size of the filler is preferably 30 μm or less, more preferably 10 μm or less, and most preferably 0.5 μm to 5 μm.
Moreover, it is preferable that the said filler is surface-treated from the point of the uniform dispersibility to the said polyolefin resin. For the surface treatment, those capable of hydrophobizing the filler surface, such as fatty acids or metal salts thereof, are preferably used.
The blending ratio of the filler is preferably 50 to 250 parts by weight with respect to 100 parts by weight of the polyolefin resin.

  The above-mentioned filler is kneaded with the polyolefin resin and melt-molded, and it can be carried out in the same manner as kneading or melt-molding in a generally known film or sheet production method. The uniaxial or biaxial stretching can be carried out in the same manner as in the usual method. In this case, in the case of uniaxial stretching, the stretching ratio is preferably 1.2 to 4.0 times. In the case of stretching, the area magnification is preferably 1.5 to 8 times.

Moreover, various 3rd components can be mix | blended with the said polyolefin resin in order to improve the various performances of the said porous sheet.
Examples of the third component include olefinic low-melting polymers, liquid or waxy hydrocarbon polymers, rubber-like materials (eg, natural rubber, isoprene rubber, butadiene rubber, etc.), olefinic thermoplastic elastomers, and styrenic thermoplastics. Additives such as elastomers or plasticizers; triglycerides; chlorinated paraffins; monoesters composed of monobasic acids and monohydric alcohols, and mixtures of polyesters composed of polybasic acids and polyhydric alcohols; polybasic acids and monohydric alcohols A mixture of polyester A comprising polybasic acid and polyhydric alcohol; a monoester having a total carbon number of 38 or more, and at least one of the acid and alcohol constituting the monoester is branched. Monoesters; hydrocarbon polymers and polyesters with side chains Mixtures thereof, and the like.

  The additive is added for the purpose of improving the tear strength in the stretching direction and the tensile stress in the transverse direction of the porous sheet. The addition amount of these additives is preferably 1 to 100 parts by weight with respect to 100 parts by weight of the polyolefin resin.

The triglyceride is a mono added to improve the sheet strength of the porous sheet and to form continuous pores in the porous sheet even at a low draw ratio, and the blending ratio of the triglyceride is 100% of the polyolefin resin 100. Preferably it is 1-100 weight part with respect to a weight part.
In addition, it is preferable that the fatty acid which comprises the said triglyceride is a C2-C30 saturated or unsaturated fatty acid.

The chlorinated paraffin is used for the same purpose as the triglyceride.
The chlorine content in the chlorinated paraffin is preferably 1 to 65% by weight, more preferably 35 to 55%. Such a chlorinated paraffin is produced by a known method, for example, by passing chlorine gas through a carbon tetrachloride solution of molten solid paraffin, n paraffin or solid paraffin.
The blending ratio of the chlorinated paraffin is preferably 1 to 100 parts by weight with respect to 100 parts by weight of the polyolefin resin.

Moreover, the monoester which consists of said monobasic acid and monohydric alcohol, and the mixture of polyester which consists of polybasic acid and a polyhydric alcohol are used for the same purpose as the said triglyceride.
Examples of the monoester include esters obtained by dehydration condensation of a monobasic acid such as a monocarboxylic acid having 10 or more carbon atoms and a monohydric alcohol such as a monoalcohol having 10 or more carbon atoms. Is a monoester having a molecular weight of 240 or more, more preferably a monoester having 20 or more carbon atoms containing a branched hydrocarbon chain.
On the other hand, examples of the polyester include polybasic acids such as dicarboxylic acids, tricarboxylic acids, and tetracarboxylic acids, and polyhydric alcohols such as diols, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, and sucrose. , A polyester obtained by dehydration condensation and having a total carbon number of 50 or more.
The blending ratio of the mixture is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the polyolefin resin.
In addition, it is thought that the said monoester contributes to the improvement of the moisture permeability of an obtained porous sheet and a vertical tear strength, and the said polyester contributes to the improvement of moisture permeability and an external appearance.

The polyester A which consists of said polybasic acid and monohydric alcohol, and the mixture of polyester B which consists of polybasic acid and polyhydric alcohol are used for the same purpose as the said triglyceride.
The polyester A is, for example, a diester, triester or tetraester obtained by dehydration condensation of a polybasic acid such as dicarboxylic acid, tricarboxylic acid or tetracarboxylic acid and a monohydric alcohol, and has a total carbon number. The thing of 30 or more is mentioned. Among these, a diester having a saponification value of 230 or less is preferable, and a diester containing a branched monohydric alcohol having 16 or more carbon atoms is more preferable.
On the other hand, examples of the polyester B include polybasic acids such as dicarboxylic acid, tricarboxylic acid, and tetracarboxylic acid, and polyhydric alcohols such as diols, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol, and sucrose. Is a polyester obtained by dehydrating and condensing a polyester having a total carbon number of 50 or more.
The blending ratio of the polyester lute A and the polyester B is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the polyolefin resin.

The monoester having a total carbon number of 38 or more, wherein at least one of the acid and alcohol constituting the monoester is branched, has a supple texture and good moisture permeability in the porous sheet. It is used for the purpose of improving the vertical tear strength while maintaining the leak-proof property.
Specifically, 2-decyltetradecyl stearate, 2-octadecyl behenate, esters of α-branched fatty acids (C18-40) and monoalcohols (C6-36) (total carbon number of 38 or more), and the like. Can be mentioned.
The blending ratio of the monoester is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the polyolefin resin.

In addition, the mixture of the hydrocarbon polymer having the above side chain and the polyester has the purpose and sheet for improving the vertical tear strength while maintaining the supple texture and good moisture-proof leakage in the porous sheet. It is used for the purpose of improving the appearance.
As the hydrocarbon polymer, poly α-olefins and those having an oligomer region having a side chain of 4 or more carbon atoms are preferably used. In addition, ethylene-propylene copolymers such as Mitsui Oil Trade name “Lucanto” manufactured by Chemical Industry Co., Ltd. and maleic acid derivatives thereof; polymers of isobutylene, for example, trade name “Polybutene HV-100” manufactured by Idemitsu Petrochemical Co., Ltd .; or oligomers of butadiene and isoprene and the like Hydrogenated products and derivatives derived from these can also be used.
On the other hand, as the polyester, for example, a polyester having a polybasic acid or a polyhydric alcohol as a constituent component is used. Specifically, castor oil, hydrogenated castor oil, ethylene oxide adduct of hydrogenated castor oil, glycols and dimer are used. Examples include polyesters with acids, hexaesters obtained from trimethylolpropane, dimer acid, and stearic acid, and hexaesters obtained from trimethylolpropane, adipic acid, and stearic acid.
The blending weight ratio of the hydrocarbon polymer to the polyester is preferably 3/7 to 7/3, but is in the range of 1/9 to 9/1 according to the desired level of moisture permeability, vertical tear strength, and appearance according to the application. You can choose freely. The blending ratio of the hydrocarbon polymer having a side chain and the mixture of the polyester is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the polyolefin resin.

In addition, the moisture permeable sheet includes (a) a crystalline polyolefin resin, and (b) being miscible with the crystalline polyolefin resin under melting of the crystalline polyolefin resin and at a temperature lower than the crystallization temperature of the crystalline polyolefin resin. A porous sheet obtained by forming a sheet from a mixture containing an organic compound to be phase-separated and stretching the sheet at least in a uniaxial direction can also be preferably used.
As a method for forming the sheet from the mixture, a normal method can be used without any particular limitation.

As the crystalline polyolefin resin, polypropylene, a blend of polypropylene and propylene-ethylene copolymer, a blend of polypropylene and polyethylene, or the like can be preferably used.
Further, as the organic compound, mineral oil, synthetic lubricating oil, paraffin wax, aliphatic carboxylic acid and polyhydric alcohol ester, or the like can be preferably used.
The compounding amounts of the crystalline polyolefin resin and the organic compound are preferably 50 to 90 parts by weight of the crystalline polyolefin resin and 50 to 10 parts by weight of the organic compound, respectively.

  Moreover, various additives, such as a crystal nucleus forming agent, can also be mix | blended with the porous sheet containing the said crystalline polyolefin resin and the said organic compound. The additive is preferably blended in an amount of 0.01 to 3 parts by weight, more preferably 0.05 to 1 part by weight, based on 100 parts by weight of the mixture of the crystalline polyolefin resin and the organic compound. .

  The draw ratio at the time of drawing the sheet formed from the mixture containing the crystalline polyolefin resin and the organic compound is preferably at least 1.2 to 5 times (area ratio) in the uniaxial direction, more preferably 1 .2 to 3 times.

In the present invention, the moisture permeable sheet used as the liquid impermeable sheet preferably has a moisture permeability of 0.5 to 4 g / (100 cm ² · hr), more preferably 0.5 to 2.5 g / hr. (100 cm ² · hr). When the above-mentioned moisture permeability is less than 0.5 g / (100 cm ² · hr), when the composite sheet of the present invention is used for the back sheet of the absorbent article, moisture permeability is insufficient and stuffiness and skin irritation are sufficient. If it exceeds 4.0 g / (100 cm ² · hr), there is a concern about leakage of liquid such as urine when the composite sheet is used as a back sheet of an absorbent article. It is not preferable. The moisture permeability is a value measured according to JIS Z-0208.
Further, the moisture permeable sheet, preferably has a basis weight of 15 to 50 g / m ^2, more preferably 15 to 35 g / m ^2.

Therefore, the liquid-impermeable sheet is a moisture-permeable sheet, and the moisture-permeable amount of the moisture-permeable sheet is particularly preferably 0.5 to 4 g / (100 cm ² · hr).

Further, the particular basis weight having a non-woven fabric used in the present invention is 15 to 35 g / m ^2, preferably 18~30g / m ^2.
When the basis weight is less than 15 g / m ² , the strength is lowered, the formation is deteriorated, and the degree of occurrence of blocking is increased. On the other hand, when it exceeds 35 g / m ² , the texture such as softness and the touch are deteriorated.

Moreover, said specific fiber diameter which the constituent fiber which comprises the said nonwoven fabric has is 1.5-3.5 denier, Preferably it is 1.5-3.0 denier.
When the fiber diameter is less than 1.5 denier, the production becomes difficult and the cost becomes high. When the fiber diameter exceeds 3.5 denier, the texture such as softness and the touch are deteriorated.

Specific examples of the constituent fibers include the following fibers.
Polyolefin fibers such as polyethylene (PE) fibers and polypropylene (PP) fibers; fibers using a thermoplastic resin such as polyethylene terephthalate (PET) and polyamide alone; composite fibers having a structure such as a core-sheath type and a side-by-side type, such as A core-sheath structure fiber in which the sheath component is polyethylene or low-melting-point polypropylene is preferable, and typical examples of the core / sheath structure fiber include PET (core) / PE (sheath), PP (core) / PE ( Sheath), fibers having a core-sheath structure such as PP (core) / low melting point PP (sheath).
More specifically, the constituent fibers preferably include polyolefin fibers such as polyethylene fibers and polypropylene fibers, polyethylene composite fibers, and polypropylene composite fibers. Here, the composite composition of the polyethylene composite fiber is polyethylene terephthalate / polyethylene, and the composite composition of the polypropylene composite fiber is preferably polyethylene terephthalate / low melting point polypropylene, more specifically, PET (core). / PE (sheath), PET (core) / low melting point PP (sheath).
These fibers may be used alone to form a nonwoven fabric, but may be used in combination of two or more.

  Moreover, it is preferable that the fiber length of the said constituent fiber is 20-80 mm, and it is still more preferable that it is 30-60 mm. If the fiber length is less than 20 mm, it is difficult to apply to a card machine, and if it exceeds 80 mm, a fiber lump (nep) is likely to occur.

And the said nonwoven fabric used in this invention will not be restrict | limited especially if it consists of the said structural fiber and has said specific basic weight, Preferably, it manufactures with the following manufacturing method using the said structural fiber. Things.
Known production methods such as a heat roll method, a suction heat bond method, a spun lace method, a spun bond method, and a melt blown method.
Accordingly, examples of the nonwoven fabric used in the present invention include a heat roll nonwoven fabric, a suction heat bond nonwoven fabric, a spunlace nonwoven fabric, and a spunbond nonwoven fabric.

The specific melt viscosity of the adhesive used in the present invention is 10,000 cps or less at 180 ° C., preferably 1000 to 8000 cps, more preferably 1000 to 6000 cps.
If the melt viscosity exceeds 10,000 cps, the coatability may be reduced, and the coated surface may become uneven or the adhesive may fall off.

The base polymer (styrene elastomer) used as a component of the hot melt adhesive is styrene butadiene rubber (SBR), styrene / butadiene / styrene block copolymer (SBS), styrene / isoprene / styrene block copolymer Examples thereof include merging (SIS), styrene / ethylene / butylene / styrene block copolymer (SEBS), and styrene / ethylene / propylene / styrene block copolymer (SEPS).
Moreover, as said APAO, a conventionally well-known thing can be especially used without a restriction | limiting, For example, a propylene / ethylene copolymer, a propylene / butene-1 copolymer, a propylene / hexene copolymer, etc. can be used. . Further, these APAOs are commercially available under trade names such as “Ubetak” (“UT2175”, etc.) manufactured by Ube Lexen, and “East Flex”, manufactured by Eastman Kodak Company.
Moreover, as said APAO, a propylene-ethylene-butene-1 terpolymer can also be used. The ternary copolymer is commercially available from Hürz under the trade name “Best Plast”.

Moreover, the said adhesive agent may contain a tackifier, a softener, and antioxidant other than the said base polymer as the structural component.
As the tackifier, those that are solid at room temperature can be preferably used. For example, C5 petroleum resin, C9 petroleum resin, dicyclopentadiene petroleum resin, rosin petroleum resin, polyterpene resin, terpene phenol resin, etc. Is mentioned. Specific examples include hydrogenated terpene resins such as “Clearon” (trade name, manufactured by Yasuhara Chemical), and hydrogenated aromatic petroleum resins such as “Arcon” (trade name, manufactured by Arakawa Chemical). Although the compounding quantity of the said tackifier can be suitably selected according to the compounding quantity etc. of the said softener to be used, it is preferable to set it as 30 to 70 weight% normally with respect to the said adhesive agent whole quantity.

Examples of the softener include process oil, mineral oil, various plasticizers, polybutene, and liquid tackifier resin having a softening point of 10 ° C. or lower and an average molecular weight of 200 to 700. Specifically, paraffinic oils such as “shelf rex” (trade name, manufactured by Shell Chemical Co., Ltd.), “PW-90” (trade name, manufactured by Idemitsu Kosan Co., Ltd.), tetraoctyl pyromellitate, jededecyl phthalate and trioctyl trimell Examples include ester oils such as tate. The blending amount of the softener is preferably 20% by weight or less based on the total amount of the adhesive. When the blending amount exceeds 20% by weight, the tackiness (sticky feeling) of the adhesive is increased, which may cause blocking between the composite sheets.
Examples of the antioxidant include “Irganox 1010” [trade name, manufactured by Ciba Geigy Co., Ltd.], “Irganox 1076” [trade name, manufactured by Ciba Geigy Co., Ltd.], or “Smilizer GM” [commercial product]. Name, manufactured by Sumitomo Chemical Co., Ltd.] and the like are preferable. The amount of the antioxidant is preferably 1 to 3 parts by weight with respect to 100 parts by weight of APAO.
In addition to the above-described components, the adhesive may further contain other components as necessary.

Moreover, the specific shape of the said adhesive agent is random fibrous form, and the fiber diameter of a fibrous adhesive agent is 15-210 micrometers, Preferably it is 20-150 micrometers.
By making the coating shape into a fiber having a random fiber diameter, it is possible to improve the adhesion without impairing the texture.
Further, if the fiber diameter is less than 15 μm, the fibers are too thin to exhibit sufficient adhesive force, and if it exceeds 210 μm, the bonded portion becomes hard and the texture of the composite sheet is lowered.

The coating amount of the adhesive is 0.5 to 7 g / m ² and preferably 0.5 to 5 g / m ² .
When the coating amount is less than 0.5 g / m ² , the adhesive strength is added, and when it exceeds 7 g / m ² , the texture is lowered.
Moreover, the number of the adhesive which cross | intersects this line when drawing a 1-cm-long line orthogonal to arbitrary one of the said fibrous adhesives is 10-40, Preferably it is 10-30 is there. That is, as shown in FIG. 1 to be described later, when a straight line 11 having a length of 1 cm is drawn in a direction orthogonal to an arbitrary piece of adhesive 10 a, the number of adhesives 10 other than 10 a intersecting the straight line 11 is The number in the above range.
If the number of adhesives is less than 10, the adhesive strength is reduced, and if it exceeds 40, the texture of the composite sheet is lowered, and when the moisture-permeable sheet is used as the liquid-impermeable sheet, the entire composite sheet The moisture permeability is reduced.

With reference to FIG. 1 and 2, the coating form of the said adhesive agent is explained in full detail.
Here, FIG. 1 is an enlarged plan view showing one form of an adhesive coating form in the composite sheet of the present invention, and FIG. 2 is an enlarged view of a portion II in FIG. 1 and 2, only the adhesive is shown and shown for convenience of explanation.
As shown in FIGS. 1 and 2, the adhesive 10 is in a fibrous form, and is applied randomly, that is, without the fibrous adhesive 10 being oriented in one direction. Here, the adhesive may be applied to either the nonwoven fabric or the liquid-impermeable sheet.
However, when it is manufactured by a manufacturing method as described later, it may be applied with a certain degree of orientation as shown in FIGS.

And the composite sheet of this invention adhere | attaches the said liquid-impermeable sheet and the said nonwoven fabric with the said adhesive agent.
As the structure of the composite sheet of the present invention, a liquid-impermeable sheet / non-woven fabric two-layer structure, a liquid-impermeable sheet / non-woven fabric / liquid-impermeable sheet and a non-woven fabric / liquid-impermeable sheet / non-woven fabric three-layer structure, etc. Various structures can be adopted.
In any structure, an adhesive is interposed between the liquid-impermeable sheet and the nonwoven fabric, and the liquid-impermeable sheet and the nonwoven fabric are bonded by this adhesive.
A composite sheet having a two-layer structure as one form of the composite sheet of the present invention will be specifically described with reference to FIG. 3. The composite sheet 1 of the present embodiment is composed of a liquid-impermeable sheet 3 and a nonwoven fabric 2 as an adhesive. 10 is bonded. Here, the liquid-impermeable sheet 3 is a liquid-impermeable sheet having the above-mentioned specific thickness, and the nonwoven fabric 2 has a specific basis weight composed of structural fibers having the above-mentioned specific fiber diameter. It is a nonwoven fabric. The adhesive 10 is an adhesive having the above-described specific melt viscosity, and is applied to the specific shape, that is, a random fiber shape, with the specific amount described above.

The composite sheet is heat embossed, and the embossed area ratio is preferably 40% or less, more preferably 5 to 40%, based on the entire composite sheet. Here, the “embossed area ratio” is a ratio of the area of the portion (fused portion) where the liquid-impermeable sheet and the nonwoven fabric are fused by heat embossing to the area of the entire composite sheet.
If the embossed area ratio exceeds 40%, the composite sheet becomes hard and the texture is lowered.
Therefore, in the composite sheet of the present invention, which is heat embossed, a large number of fused portions in the shape of pins, dot dots, turtle shells, lattices, vertical stripes, horizontal stripes, stitches, patterns, etc. are formed in a predetermined pattern It will be. The predetermined pattern is not particularly limited.
Note that the size and interval of the convex portions are arbitrary as long as the embossed area ratio is satisfied. Therefore, the interval between the fused portions formed on the composite sheet is also arbitrary depending on the desired shape of the fused portion. However, as shown in FIG. 3, the fused portion 1 a extends over the entire surface of the composite sheet 1. It is preferable to be formed.

The composite sheet preferably has moisture permeability, specifically 0.5 g / (100 cm ² · hr) or more.

The composite sheet of the present invention has a sufficient adhesive force, no blocking, and a good texture because the liquid-impermeable sheet and the nonwoven fabric are bonded together under the adhesive coating conditions described above. .
Accordingly, in the absorbent article such as a disposable diaper having a top sheet, a back sheet, and an absorber interposed between both sheets, the back sheet, sanitary materials such as nursing disposable sheets, clothing materials, rain gears and simple jumpers Useful as such.

Next, the preferable manufacturing method of the composite sheet of this invention is demonstrated.
The composite sheet of the present invention has an adhesive coating step in which the adhesive is sprayed in a fiber form on the liquid-impermeable sheet or the nonwoven fabric, and the nonwoven fabric or the above-mentioned surface on the coated surface. It can manufacture by performing the bonding process which bonds a liquid-impermeable sheet.
In addition, processes other than the said adhesive agent coating process and the said bonding process, for example, the formation process of the said liquid-impermeable sheet, etc. are the same as that of a well-known manufacturing method.

The adhesive coating process will be described.
In order to spray the adhesive into a fiber shape, a known curtain spray method, slot spray method, and the like using a hot melt adhesive application device described in JP-A-5-309310 and JP-A-6-210228, It can be carried out by performing a melt blown method or the like.

The main part of the hot melt adhesive coating apparatus preferably used in the adhesive coating process will be described with reference to FIG.
Here, FIG. 4 is a partially broken perspective view showing a main part (nozzle unit) of a hot melt adhesive application apparatus preferably used in the present invention.
The nozzle unit 21 of the hot melt adhesive applicator shown in FIG. 4 has a rectangular shape as a whole, and has a plate-like shim 22 fitted substantially at the center in the width direction of the nozzle unit 21, and a lower side from both sides of the nozzle unit 21. The air injection path 23 is formed over the opposite end surface, and the adhesive injection path 24 is formed from the upper end of the nozzle unit 21 to the middle in the width direction of the shim 22. One side edge of the shim 22 is located on the lower end surface of the nozzle unit 21, and an adhesive discharge port 25 is formed by a portion located on the lower end surface. The air injection path 23 forms an air outlet 26 on the lower end surface of the nozzle unit. The air jets 26 are provided on both the left and right sides of the adhesive discharge port 25.

The shim 22 includes a strip-shaped plate portion 22a formed on the upper side and a comb-shaped portion 22b having a large number of slits 22c formed on the lower side. The lower end portion of the comb-shaped portion 22b An adhesive discharge port 25 is formed. Here, each said slit 22c is formed over the width direction whole region of this comb-shaped part 22b, respectively.
The width of the slit 22c is preferably 0.3 to 0.8 mm, the pitch is preferably 1.0 to 2.0 mm, the length is preferably 5 to 15 mm, and the thickness is It is preferably 0.1 to 0.4 mm.

The nozzle unit 21 operates as follows.
That is, the adhesive supplied from the adhesive supply section (not shown) through the adhesive injection path 24 is injected into the shim 22 and the air supplied from the air supply section (not shown) through the air injection path 23. And air is injected from the air outlet 26. The supplied adhesive is made into a linear shape substantially equal to the shape of the slit 22c by the shim 22, and this linear adhesive is supplied to the adhesive discharge port 25 and discharged. Then, the adhesive discharged from the adhesive discharge port 25 is made into a fiber by the air jetted from the air outlet 26 and is applied to the coating surface.
The air is preferably heated air. The temperature of the air is preferably the same as or higher than the melting point of the adhesive by 50 ° C. or more, more preferably 50 to 120 ° C. higher than the melting point. The air injection pressure is preferably 1.0 to 3.0 kg / cm @ 3.

  The said bonding process can be performed by pressing and applying a pressure after bonding a liquid-impermeable sheet and a nonwoven fabric similarly to the manufacturing method of a well-known composite sheet.

Moreover, in this invention, it is preferable to give a heat embossing in this bonding process.
The hot embossing may be performed in-line simultaneously with the adhesive coating step, or may be post-processed and performed in outline.
The hot embossing can be performed using an embossing roll. As the embossing roll, a pair of rolls generally composed of an engraving roll and a smooth roll can be used. At this time, the surface pressed by the engraving roll may be any of the surface of the heat roll nonwoven fabric and the surface of the liquid impermeable sheet.
As the engraving roll, for example, an iron roll having various patterns engraved on its surface can be used. On the other hand, as the smooth roll, a paper roll, a rubber roll, a silicon rubber roll, a urethane rubber roll, a metal roll, or the like is used. Can do.

In the hot embossing, the laminated sheet before hot embossing may be preheated with a heating roll. Moreover, you may give a heat embossing as a heating roll which can heat the said embossing roll itself.
The temperature of the heat embossing is preferably set to a temperature of 10 ° C. or lower than the melting point of the constituent fibers of the heat roll nonwoven fabric or the liquid impervious sheet that are in direct contact with the heating roll. Heating at a temperature exceeding 10 ° C. lower than the melting point is not preferable because the composite sheet is fused to the roll or shrinkage or wrinkles due to heat occurs.

Moreover, it can also heat-emboss by making a temperature difference between a sculpture roll and a smooth roll, and in this case, a soft texture is obtained in the resulting composite sheet, which is preferable.
Examples of the engraving roll pattern include pins, dot dots, turtle shells, lattices, vertical stripes, horizontal stripes, stitches, patterns, and the like, and the patterns are not particularly limited.
Moreover, it is preferable that the linear pressure at the time of hot embossing is 20-120 kg / cm. If the linear pressure is 20 kg / cm or less, the effect of hot embossing may be reduced, and if it exceeds 120 kg / cm, the composite sheet is likely to be perforated, which is not preferable.
The conditions for the hot embossing are not limited to these ranges because the influence of the processing speed is large.

Next, a method for producing the composite sheet of the present invention will be described with reference to FIG.
Here, FIG. 5 is a schematic view showing the main part of the method for producing the composite sheet shown in FIG.

The composite sheet 1 having the form shown in FIG. 3 is manufactured as shown in FIG.
That is, as shown in FIG. 5, the nonwoven fabric 2 is unwound from the unwinding roll 2 ′. Further, the liquid-impermeable sheet 3 is unwound from the unwinding roll 3 ′. And the adhesive agent 10 is apply | coated to random fiber form on this liquid-impermeable sheet | seat 3 using adhesive agent application apparatus 10 'which has a nozzle unit as shown in FIG. 4, and an adhesive agent coating process is performed.
Next, the liquid-impermeable sheet 3 coated with the adhesive 10 and the nonwoven fabric 2 are passed through the nip rolls 30 and 30 to obtain a laminated sheet 1 ′. The composite sheet 1 is obtained by passing through an embossing roll composed of 31 and a smooth roll 32 and performing hot embossing to perform a bonding step.
The composite sheet 1 manufactured through the embossing process is guided to the take-up roll 34 by the guide rolls 33 and 33 and taken up.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

〔Example〕
An adhesive (melt viscosity: 180 ° C./2000 cps) having the composition shown in [Table 1] on a moisture-permeable sheet having a thickness of 20 μm was used by a melt blown method (an apparatus having a nozzle unit shown in FIG. 4). In addition, air was applied at a temperature of 190 ° C., and hot air having a pressure of 2.0 kg / cm ² was used to form a random fiber (coating amount 1.0 g / m ² , coating temperature 170). ° C, coating speed 200 m / min).
A suction heat bond nonwoven fabric having a fiber diameter of 1.5 denier, a basis weight of 22 g / m ² , and a thickness of 0.5 mm under a load of 0.5 g / cm ² is pasted on the coated surface. Combined, it became a composite sheet.

The moisture-permeable sheet is as described below.
100 parts by weight of linear low density polyethylene [Ultzex 2520F, manufactured by Mitsui Petrochemical Co., Ltd.] and 150 parts by weight of surface-treated calcium carbonate (average particle size: 1 μm), composition and physical property values shown in [Table 3] An ester composition having 10 parts by weight was added and kneaded with a twin screw kneader to produce pellets. The obtained pellets were supplied to an inflation molding machine to mold an inflation sheet having a thickness of 40 μm. The obtained sheet was stretched to a stretching ratio of 2.3 times at a stretching temperature of 50 ° C. using a roll stretching machine to obtain a porous moisture-permeable sheet. This moisture-permeable sheet was used as the moisture-permeable sheet. The thickness of this sheet was 20 μm, the moisture permeability was 1.8 g / (100 cm ² · h), and the basis weight was 20 g / m ² .

About the obtained composite sheet, the adhesive strength in 25 mm width and the blocking strength in 50 mm width were measured by the following method. The results are shown in [Table 3].
Moreover, the disposable diaper was produced using the obtained composite sheet. The obtained disposable diaper was prevented from being stuffed and improved in texture and feel such as softness.

<Measurement method of adhesive strength>
A test piece having a width of 25 mm along the MD direction of the composite sheet and a length of 100 mm along the CD direction of the composite sheet was cut out from the composite sheet. The test piece was subjected to a 180 ° peel test (tensile speed 300 mm / min, measurement temperature 20 ° C.) in the CD direction using a Tensilon tensile tester to measure the adhesive strength between the liquid-impermeable sheet and the nonwoven fabric.
<Measurement method of blocking strength>
The composite sheet was rolled around a paper tube about 1000 m and stored in an atmosphere at 50 ° C. for 1 week. After storage, allow sufficient cooling time, and with the composite sheet overlapping two 30 mm portions radially outward from the paper tube, the width of 50 mm along the CD direction of the composite sheet × the composite sheet A sample having a length of 100 mm was cut out along the MD direction and used as a test piece. The test piece was subjected to a 180 ° peel test (peel test between two composite sheets, tensile speed 500 m / min, measurement temperature 20 ° C.) in the MD direction using a Tensilon tensile tester to measure the blocking strength.

[Examples 2 to 4 and Comparative Examples 1 to 4]
A composite sheet was obtained in the same manner as in Example 1 except that the fiber diameter and the number of the adhesive were as shown in [Table 3], and the obtained composite sheet was evaluated in the same manner as in Example 1. The results are shown in [Table 3].

As is clear from the results shown in [Table 1], the composite sheet of the present invention has high adhesive strength, does not cause blocking, and has excellent texture. On the other hand, when the fiber diameter of the adhesive is 8 μ as in Comparative Example 1, sufficient adhesive strength is not obtained. When the fiber diameter of the adhesive is 240 μ as in Comparative Example 2, the blocking strength is too high to cause material destruction, and the texture is reduced. As in Comparative Example 3, the coating amount is 1.0 g / m ² as in Example 3, but the same phenomenon as in Comparative Example 2 is observed when the fiber diameter is 240 μm. Moreover, in the case of the comparative example 4, although the adhesive force is acquired, a texture will fall and moisture permeability will fall.

FIG. 1 is an enlarged plan view showing one form of an adhesive coating form in the composite sheet of the present invention. FIG. 2 is an enlarged view of part II in FIG. FIG. 3 is a partially broken perspective view showing one embodiment of the composite sheet of the present invention. FIG. 4 is a partially broken perspective view showing a main part (nozzle unit) of a hot melt adhesive application apparatus preferably used in the present invention. FIG. 5 is a schematic view showing the main part of the method for producing the composite sheet shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Composite sheet 2 Liquid impervious sheet 3 Nonwoven fabric 10 Adhesive

Claims (4)

In a composite sheet formed by adhering a liquid-impermeable sheet and a nonwoven fabric via an adhesive,
The liquid-impermeable sheet has a thickness of 15 to 40 μm,
The nonwoven fabric is composed of constituent fibers having a fiber diameter of 1.5 to 3.5 denier, and has a basis weight of 15 to 35 g / m ² .
The adhesive is a hot melt adhesive based on a styrene elastomer, ethylene vinyl acetate copolymer or amorphous polyalphaolefin, and has a melt viscosity of 10000 cps or less at 180 ° C. The fiber diameter of the fibrous adhesive is 15 to 210 μm, the coating amount of the adhesive is 0.5 to 7 g / m ² , and any one of the fibrous adhesives is applied. The number of adhesives crossing the line when a 1 cm long line is drawn in a direction perpendicular to the book is 10 to 40,
A composite sheet characterized by that. The composite sheet according to claim 1, wherein the liquid-impermeable sheet is a moisture-permeable sheet, and the moisture-permeable amount of the moisture-permeable sheet is 0.5 to 4 g / (100 cm ² · hr).   The composite sheet according to claim 1, wherein the composite sheet is heat embossed and has an embossed area ratio of 40% or less with respect to the entire composite sheet. A method for producing a composite sheet according to claim 1,
On the liquid-impermeable sheet or non-woven fabric, an adhesive coating process in which an adhesive is sprayed and applied in a fiber shape; and
The manufacturing method of the composite sheet | seat characterized by including the bonding process which bonds a nonwoven fabric or a liquid-impermeable sheet | seat on this coated surface.

Images