Laminated nonwoven fabric and method for manufacturing the same

Abstract

To provide a laminated nonwoven fabric which easily adjusts air permeability and moisture permeability.SOLUTION: A laminated nonwoven fabric is obtained by laminating a first nonwoven fabric, synthetic paper and a second nonwoven fabric in this order, heating the laminated material and then cooling the laminated material. The first nonwoven fabric and the second nonwoven fabric contain core-sheath type composite long fibers having a sheath component composed of high density polyethylene and a core component composed of polyester having a melting point higher than the melting point of the high density polyethylene as constitutional fibers. The synthetic paper is obtained by uniformly mixing core-sheath type composite short fibers having a sheath component composed of high density polyethylene and a core component composed of polyester having a melting point higher than the melting point of the high density polyethylene, and a polyolefin-based synthetic pulp having a multiple branch structure. The core-sheath type composite short fibers have a fiber diameter of 3 to 30 μm and a fiber length of 2 to 30 mm. The polyolefin-based synthetic pulp has a fiber length of 0.1 to 5 mm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminated nonwoven fabric having desired breathability and moisture permeability, and a method for producing the same, and more particularly to a laminated nonwoven fabric and a method for producing the same that are suitable for storing powders such as deodorizers and desiccants to obtain bag-like objects. [Background technology]

[0002] Laminated nonwoven fabrics with predetermined breathability and moisture permeability have been used for various purposes. For example, they are used as materials for protective clothing, reinforcing materials for microporous membrane filters, or as materials for bags used to store powders such as deodorizers and desiccants. The applicant has proposed a nonwoven fabric with the following three-layer structure as such a laminated nonwoven fabric (Patent Document 1). Specifically, the surface layer consists of an aggregate of core-sheath type composite long fibers in which the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than the melting point of the high-density polyethylene; the intermediate layer consists of an aggregate of core-sheath type composite short fibers in which the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than the melting point of the high-density polyethylene, and single-phase short fibers made of polyester having a melting point higher than the melting point of the high-density polyethylene; and the back layer consists of a sheath component made of high-density polyethylene or linear low-density polyethylene and a core component made of the high This proposal proposes a laminated nonwoven fabric consisting of an aggregate of core-sheath type composite long fibers made of polyester having a melting point higher than that of high-density polyethylene or linear low-density polyethylene. The core-sheath type composite short fibers and single-phase short fibers constituting the intermediate layer have a fiber length of 2 to 30 mm, and the fiber diameter of the single-phase short fibers is smaller than that of the core-sheath type composite short fibers, with the single-phase short fibers having a fiber diameter of 3 to 10 μm. The surface layer, intermediate layer, and back layer are bonded together by at least a portion of the sheath component of the core-sheath type composite long fibers and core-sheath type composite short fibers constituting each layer, which is in a molten and solidified state.

[0003] [Patent Document 1] Patent No. 6560095 [Overview of the project] [Problems that the invention aims to solve]

[0004] This invention is an improvement on the invention described in Patent Document 1, and aims to make it easier to adjust breathability and moisture permeability. [Means for solving the problem]

[0005] The present invention solves the above problems by uniformly mixing polyolefin-based synthetic pulp having a multi-branched structure in the intermediate layer. That is, the present invention is a laminated nonwoven fabric comprising three layers: a surface layer, an intermediate layer, and a back layer. The surface layer consists of an aggregate of first-core-sheath type composite long fibers, the sheath component of which is high-density polyethylene and the core component of which is polyester having a melting point higher than the melting point of the high-density polyethylene. The intermediate layer consists of an aggregate of core-sheath type composite short fibers, the sheath component of which is high-density polyethylene and the core component of which is polyester having a melting point higher than the melting point of the high-density polyethylene, and polyolefin-based synthetic pulp having a multi-branched structure, all uniformly mixed together. The back layer consists of a sheath component of which is polyethylene and the core component of which is polyester... The present invention relates to a laminated nonwoven fabric and a method for manufacturing the same, characterized in that it is made up of an aggregate of second core-sheath type composite long fibers made of polyester having a melting point higher than that of Len, the core-sheath type composite short fibers constituting the intermediate layer have a fiber diameter of 3 to 30 μm and a fiber length of 2 to 30 mm, the polyolefin pulp has a fiber length of 0.1 to 5 mm, and the three layers are fixed and integrated by the softening, melting and solidification of the sheath component of the first core-sheath type composite long fibers, the sheath component of the core-sheath type composite short fibers, the sheath component of the second core-sheath type composite long fibers, and the polyolefin synthetic pulp constituting each layer. Here, multi-branching means that further branching is formed from the branch portions that branch off from the main portion, and therefore, the multi-branching structure is a fine fibrillated structure.

[0006] [About the surface layer] The surface layer consists of an aggregate of first-core-sheath type composite long fibers, where the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than that of high-density polyethylene. The first-core-sheath type composite long fibers are bonded together by the softening, melting, and solidification of the high-density polyethylene sheath component. The melting point of the high-density polyethylene is preferably 120 to 140°C, and the melting point of the polyester core component is preferably 250 to 260°C. By setting the melting points of both materials within this range, the difference in melting points between the high-density polyethylene and polyester is large, and when the high-density polyethylene softens or melts, the polyester does not soften or melt or deteriorate, maintaining its original fiber form. As a result, a large number of micropores are maintained in the surface layer.

[0007] The mass ratio of the core component to the sheath component in the first core-sheath type composite long fiber is arbitrary, but it is preferably core component:sheath component = 0.25 to 4:1, more preferably core component:sheath component = 0.4 to 2.5:1, and most preferably core component:sheath component = 1:1. If the mass ratio of the sheath component falls below this range, the bonding between the first core-sheath type composite long fibers tends to become insufficient, or the fixation and integration of the surface layer and the intermediate layer tends to become insufficient. Also, if the weight ratio of the sheath component falls above this range, the surface layer tends to become film-like, and it becomes difficult for micropores to remain.

[0008] The single fiber fineness of the first core-sheath type composite long fiber is arbitrary, but from the perspective of physical properties such as tensile strength, it is preferably 1 to 7 dtex. If the single fiber fineness is less than 1 dtex, the tensile strength of the surface layer tends to decrease. Also, if the fineness exceeds 7 dtex, the gaps between the first core-sheath type composite long fibers become larger, making it difficult to adjust the moisture permeability.

[0009] The mass of the surface layer is arbitrary, but generally it is 10-50 g / m². 2 Preferably, the mass of the surface layer is 10 g / m². 2 When the mass falls below 50 g / m², the intermediate layer tends to become exposed, making it difficult to protect. Also, the surface layer mass is 50 g / m². 2 Beyond that point, there is a tendency towards over-engineering, which is not rational.

[0010] [About the middle class] The intermediate layer is composed of an aggregate of core-sheath type composite short fibers, in which the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than that of the high-density polyethylene, and polyolefin-based synthetic pulp having a multi-branched structure, which are uniformly mixed together. The high-density polyethylene and polyester used are the same as those used in the first core-sheath type composite long fibers. The mass ratio of the core component to the sheath component of the core-sheath type composite short fibers is also about the same as that of the first core-sheath type composite long fibers used in the surface layer. The fiber diameter of the core-sheath type composite short fibers is 3 to 30 μm and the fiber length is 2 to 30 mm. Core-sheath type composite short fibers with a fiber diameter of less than 3 μm or a fiber length of less than 2 mm are difficult to manufacture and are not practical. If the fiber diameter exceeds 30 μm or the fiber length exceeds 30 mm, it becomes difficult to uniformly mix with the polyolefin-based synthetic pulp, which is undesirable.

[0011] The fiber length of the polyolefin-based synthetic pulp having a multi-branched structure is 0.1 to 5 mm, preferably 0.5 to 3 mm. If the fiber length of the synthetic pulp is less than 0.1 mm, it becomes difficult to intertwine with the core-sheath type composite short fibers, making uniform mixing difficult, which is undesirable. If the fiber length of the synthetic pulp exceeds 5 mm, the entanglement between the synthetic pulp fibers becomes strong, making uniform mixing with the core-sheath type composite short fibers difficult, which is also undesirable.

[0012] Examples of materials used for polyolefin-based synthetic pulp having a multi-branched structure include high-density polyethylene, linear low-density polyethylene, low-density polyethylene, polypropylene (propylene homopolymer), ethylene-propylene copolymer mainly composed of propylene, ethylene-propylene-butene-1 copolymer mainly composed of propylene, polybutene-1, polyhexene-1, polyoctene-1, poly-4-methylpentene-1, polymethylpentene, 1,2-polybutadiene, and 1,4-polybutadiene. Among these, high-density polyethylene is particularly preferred. This is because it is made of the same material as the sheath component of core-sheath type composite short fibers, resulting in stronger bonding due to the softening, melting, and solidification of the sheath component of the core-sheath type composite short fibers.

[0013] In the intermediate layer, the mixing ratio of core-sheath type composite short fibers and polyolefin-based synthetic pulp is preferably 10 to 150 parts by mass of polyolefin-based synthetic pulp per 100 parts by mass of core-sheath type composite short fibers, and more preferably 25 to 60 parts by mass. If the amount of polyolefin-based synthetic pulp is less than 10 parts by mass, it tends not to form a dense intermediate layer. On the other hand, if the amount of polyolefin-based synthetic pulp exceeds 150 parts by mass, it tends to drastically reduce the air permeability or moisture permeability. By appropriately changing this mixing ratio within the above range, the air permeability and moisture permeability can be adjusted, and a laminated nonwoven fabric with the desired degree of air permeability or air permeability and moisture permeability can be obtained.

[0014] The mass of the intermediate layer is 10-70 g / m³ 2 Preferably, it is 15-50 g / m². 2 It is preferable that the mass of the intermediate layer be 10 g / m³. 2 If the mass is less than 70g / m³, it tends to be too thin and does not easily form a dense intermediate layer. 2 Beyond that point, it becomes over-engineered and expensive, which is not rational.

[0015] [About the back layer] The back layer consists of an aggregate of second-core-sheath type composite long fibers, where the sheath component is polyethylene and the core component is polyester having a melting point higher than that of polyethylene. The second-core-sheath type composite long fibers are bonded together by the softening, melting, and solidification of the polyethylene sheath component. The melting point of polyethylene is preferably 75 to 140°C, and the melting point of polyester, the core component, is preferably 250 to 260°C. By setting the melting points of both materials within this range, the difference in melting points between polyethylene and polyester is large, and when the polyethylene softens or melts, the polyester does not soften or melt or deteriorate, maintaining its original fiber form. As a result, a large number of micropores are maintained in the back layer as well. The mass ratio of the core component to the sheath component and the single fiber fineness of the second-core-sheath type composite long fibers are the same as in the case of the first-core-sheath type composite long fibers. The mass of the back layer is also the same as that of the surface layer.

[0016] As the polyethylene which is the sheath component of the second core-sheath type composite long fiber, low density polyethylene, linear low density polyethylene or high density polyethylene is used. When high density polyethylene is used, the second core-sheath type composite long fiber and the first core-sheath type composite long fiber become the same kind, and the back layer becomes the same as the front layer. Therefore, a laminated nonwoven fabric without front-back difference is obtained.

[0017] On the other hand, when low density polyethylene or linear low density polyethylene is used as the polyethylene which is the sheath component of the second core-sheath type composite long fiber, a laminated nonwoven fabric with front-back difference can be obtained. Since linear low density polyethylene etc. has a lower melting point than high density polyethylene, the back layer can be used as a heat seal layer. For example, if the laminated nonwoven fabric is folded in two so that the back layers of the laminated nonwoven fabric overlap, and the three peripheral edges are heat sealed with a heat sealer, a bag-like object can be obtained. Also, if the back layers of two laminated nonwoven fabrics overlap and the four peripheral edges are heat sealed with a heat sealer, a bag-like object can be obtained. The heat seal temperature may be set at a temperature at which the high density polyethylene of the front layer does not soften or melt, but the linear polyethylene etc. of the back layer softens or melts. Therefore, even when passed through a heat sealer, damage or deterioration of the front layer can be prevented. And at this time, if powders such as a deodorant or a desiccant are stored in the bag-like object, a deodorant or a desiccant etc. of the bag can be manufactured.

[0018] [Regarding the relationship of each layer] The front layer and the intermediate layer are integrated with each other by softening or melting and solidifying the sheath component of the first core-sheath type composite long fiber in the front layer, the sheath component of the core-sheath type composite short fiber in the intermediate layer, and the polyolefin synthetic pulp. The intermediate layer and the back layer are integrated with each other by softening or melting and solidifying the sheath component of the core-sheath type composite short fiber in the intermediate layer, the polyolefin synthetic pulp, and the sheath component of the second core-sheath type composite long fiber in the back layer. Therefore, between each layer of the front layer, the intermediate layer, and the back layer, they are fixedly integrated and difficult to peel off.

[0019] [Physical Properties of the Laminated Nonwoven Fabric] Since the laminated nonwoven fabric according to the present invention has a polyolefin-based synthetic pulp having a multi-branched structure in the intermediate layer, a large number of finer voids are formed, and it has desired air permeability and moisture permeability. The fine voids formed in the laminated nonwoven fabric according to the present invention preferably have an average pore diameter of 1 to 9 μm. When the average pore diameter is less than 1 μm, the air permeability and moisture permeability tend to decrease too much. Also, when the average pore diameter exceeds 9 μm, it tends to be difficult to adjust the moisture permeability. Here, the average pore diameter refers to the mean flow pore size (MFP) measured based on ASTM F-361-86. Specifically, it was measured using a palm porometer (manufactured by POROUS MATERIALS, INC).

[0020] Regarding the air permeability of the laminated nonwoven fabric according to the present invention, the upper limit of the air permeability is preferably an air permeability of 3.0 cc / cm 2 / sec, and the lower limit of the air permeability is preferably an air permeability of 200 seconds / 100 cc. The air permeability is measured by the air permeability A method (Frazer type method) described in JIS L 1096. In the case of this measurement method, when the air permeability is less than 0.3 cc / cm 2 / sec, since it exceeds the lower limit of the measurement device of the Frazer type method, the air permeability cannot be measured. Therefore, the range where the air permeability is less than 0.3 cc / cm 2 / sec is indicated by the air permeability according to the Gurley tester method described in JIS P 8117. When the air permeability exceeds 3.0 cc / cm 2 / sec, there is a risk that it becomes difficult to adjust the moisture permeability. Also, when the air permeability exceeds 200 seconds / 100 cc, the air permeability tends to decrease too much.

[0021] Regarding the moisture permeability of the laminated nonwoven fabric according to the present invention, the moisture permeability is preferably 4800 to 12000 g / m 2 / 24 hr. When the moisture permeability is less than 4800 g / m 2 / 24 hr, the moisture permeability tends to decrease too much. Also, when the moisture permeability is more than 12000 g / m 2If the humidity exceeds 24 hours, there is a risk of minute water droplets permeating through. Note that the moisture permeability is measured using the A-1 method (calcium chloride method) described in JIS L 1099, under environmental conditions of 40°C × 90% RH.

[0022] [Regarding the manufacturing method of laminated nonwoven fabrics] The laminated nonwoven fabric according to the present invention is manufactured by laminating a first nonwoven fabric which forms the surface layer, a synthetic paper which forms the intermediate layer, and a second nonwoven fabric which forms the back layer in that order, heating and then cooling, thereby fixing and integrating the first nonwoven fabric, the synthetic paper, and the second nonwoven fabric.

[0023] The first nonwoven fabric is composed of first-core-sheath type composite long fibers, in which the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than that of high-density polyethylene. The first nonwoven fabric can be obtained by conventionally known methods such as the spunbond method. The constituent fibers may be simply entangled with each other, or they may be partially or completely fused by the sheath component. Fusion by the sheath component is preferable because it is easier to handle. The core-sheath component ratio and single fiber fineness of the first-core-sheath type composite long fibers are as described in the section on the surface layer above. The basis weight of the first nonwoven fabric may be about the same as the mass of the surface layer, 10 to 50 g / m². 2 It is to that extent.

[0024] Synthetic paper is made by uniformly mixing core-sheath type composite short fibers, in which the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than that of high-density polyethylene, with polyolefin-based synthetic pulp having a multi-branched structure. Such synthetic paper can be obtained by making paper from a slurry in which the core-sheath type composite short fibers and polyolefin-based synthetic pulp are uniformly dispersed using a paper machine. In order to uniformly disperse the core-sheath type composite short fibers and polyolefin-based synthetic pulp in water, the fiber length of the core-sheath type composite short fibers should not be too long or the fiber diameter too large compared to the polyolefin-based synthetic pulp. Since the fiber length of polyolefin-based synthetic pulp is generally 0.1 to 5 mm, the fiber length of the core-sheath type composite short fibers should be 2 to 30 mm. Also, since the fiber diameter of the trunk and branched parts of polyolefin-based synthetic pulp is generally about 2 to 30 μm, the fiber diameter of the core-sheath type composite short fibers should be 3 to 30 μm.

[0025] The second nonwoven fabric is composed of second-core-sheath type composite long fibers, in which the sheath component is made of polyethylene and the core component is made of polyester having a melting point higher than that of polyethylene. The polyethylene that forms the sheath component may be high-density polyethylene, as with the first-core-sheath type composite long fibers, or it may be low-density polyethylene with a lower melting point than high-density polyethylene, especially linear low-density polyethylene. The second nonwoven fabric can also be obtained by conventionally known methods such as the spunbond method, and the constituent fibers may simply be entangled with each other, or they may be partially or completely fused by the sheath component. The core-sheath component ratio and single fiber fineness of the second-core-sheath type composite long fibers may be similar to those of the first-core-sheath type composite long fibers, and the basis weight of the second nonwoven fabric may be similar to that of the backing layer, 10-50 g / m². 2 It is to that extent.

[0026] The first nonwoven fabric, synthetic paper, and second nonwoven fabric are laminated in that order, heated, and optionally pressurized, and then cooled to obtain a laminated nonwoven fabric. The heating temperature, heating method, linear pressure of pressurization, and pressurization method are arbitrary, but only the sheath component in the first core-sheath type composite long fibers, the sheath component in the core-sheath type composite short fibers, the polyolefin-based synthetic pulp, and the sheath component in the second core-sheath type composite long fibers are softened or melted to that extent. As a result, the first core-sheath type composite long fibers in the first nonwoven fabric fuse with each other, with the first core-sheath type composite long fibers, with the core-sheath type composite short fibers and synthetic pulp, with the core-sheath type composite short fibers and synthetic pulp, with the second core-sheath type composite long fibers in the second nonwoven fabric, with the second core-sheath type composite long fibers, with the core-sheath type composite short fibers and synthetic pulp, and the first nonwoven fabric, synthetic paper, and second nonwoven fabric are fused together and solidified into a single unit. Furthermore, since the core components in the first core-sheath type composite long fibers, the core components in the core-sheath type composite short fibers, and the core components in the second core-sheath type composite long fibers maintain their original fiber morphology, numerous fine voids are formed in the laminated nonwoven fabric.

[0027] As described above, a laminated nonwoven fabric is obtained having a surface layer derived from the first nonwoven fabric, an intermediate layer derived from synthetic paper, and a back layer derived from the second nonwoven fabric. The laminated nonwoven fabric according to the present invention has numerous fine voids formed within it, and possesses the desired breathability and moisture permeability. Therefore, the laminated nonwoven fabric according to the present invention can be used in a variety of applications, such as a material for protective clothing, a leak-proof material for disposable diapers and sanitary napkins, a reinforcing material for microporous membrane filters, or a material for bag-like containers for storing powders such as deodorizers and desiccants. [Effects of the Invention]

[0028] The laminated nonwoven fabric according to the present invention comprises a surface layer, an intermediate layer, and a back layer that are fixed and integrated together. The intermediate layer is made of a uniform mixture of polyolefin-based synthetic pulp and core-sheath type composite short fibers. Since the polyolefin-based synthetic pulp has a multi-branched structure, the size and number of fine voids can be adjusted by changing the mixing ratio with the core-sheath type composite short fibers. Therefore, it is possible to obtain a laminated nonwoven fabric with desired breathability and moisture permeability. [Examples]

[0029] Example 1 [Preparation of the first and second nonwoven fabrics] Polyester with a melting point of 256°C and high-density polyethylene with a melting point of 134°C were introduced into a composite melt spinning apparatus. Core-sheath type composite long fibers, with polyester as the core component and high-density polyethylene as the sheath component, were melt-spun and accumulated on a conveyor to obtain a long fiber web. This long fiber web was introduced into an embossing apparatus consisting of a heated embossing roll and a smoothing roll, where only the high-density polyethylene, which is the sheath component, was melted and solidified to obtain a nonwoven fabric in which the core-sheath type composite long fibers were bonded together. The fiber diameter of the core-sheath type composite long fibers was 3.3 dtex (fiber diameter 20 μm), and the weight ratio of the core component to the sheath component was 1:1. The basis weight of the nonwoven fabric was 15 g / m². 2 This nonwoven fabric was prepared as the first nonwoven fabric and the second nonwoven fabric.

[0030] [Preparing the synthetic paper] Core-sheath type composite short fibers (fiber diameter 13 μm × fiber length 5 mm), consisting of polyester with a melting point of 256°C as the core component and high-density polyethylene with a melting point of 134°C as the sheath component, were mixed with polyethylene-based synthetic pulp with a multi-branched structure (Mitsui Chemicals, Inc., "SWP" grade E-620) in a mass ratio of core-sheath type composite short fibers:synthetic pulp = 80:20. The mixture was dispersed in water to obtain a slurry. After forming paper from this slurry using a paper machine, it was dried by passing it through a Yankee dryer, resulting in a basis weight of 30 g / m². 2 We obtained synthetic paper.

[0031] [Manufacturing of laminated nonwoven fabrics] The first nonwoven fabric, synthetic paper, and second nonwoven fabric were laminated in that order, preheated to 135°C without pressure, and then passed between a smooth resin roll and a smooth steel roll with its surface heated to 120°C, applying a linear pressure of 200 kgf / cm to obtain a laminated nonwoven fabric. The resulting laminated nonwoven fabric had a basis weight of 60 g / m². 2 , average pore size 6μm, air permeability 1.6cc / cm 2 / sec, moisture permeability 9000g / m 2 The result was / 24hr. Furthermore, even when the laminated nonwoven fabric was folded and bent, the layers remained firmly bonded.

[0032] Example 2 A laminated nonwoven fabric was obtained using the same method as in Example 1, except that the mass ratio of core-sheath type composite short fibers to synthetic pulp was changed to core-sheath type composite short fibers:synthetic pulp = 60:40 to prepare the synthetic paper. The obtained laminated nonwoven fabric had a basis weight of 60 g / m². 2 Average pore size 4 μm, air permeability 55 seconds / 100 cc (air permeability is 0.3 cc / cm²). 2 It is less than / sec.), moisture permeability 7200g / m 2 The result was / 24hr. Furthermore, even when the laminated nonwoven fabric was folded and bent, the layers remained firmly bonded.

[0033] Example 3 The same materials used in Example 1 were prepared as the first nonwoven fabric and synthetic paper. For the second nonwoven fabric, the high-density polyethylene used in Example 1 was replaced with linear low-density polyethylene with a melting point of 102°C, except that the second nonwoven fabric was prepared in the same manner as in Example 1. [Manufacturing of laminated nonwoven fabrics] The first nonwoven fabric, synthetic paper, and second nonwoven fabric were laminated in that order. Under no pressure, the first nonwoven fabric side was preheated to 135°C and the second nonwoven fabric side to 130°C. Then, the laminated nonwoven fabric was passed between a smooth resin roll and a smooth steel roll whose surface was heated to 120°C, with a linear pressure of 200 kgf / cm applied, to obtain a laminated nonwoven fabric. The obtained laminated nonwoven fabric had a basis weight of 60 g / m². 2 , average pore size 6μm, air permeability 1.4cc / cm 2 / sec, moisture permeability 8800g / m 2 The result was / 24hr. Furthermore, even when the laminated nonwoven fabric was folded and bent, the layers remained firmly bonded. This laminated nonwoven fabric could be used with a heat-sealed back layer derived from the second nonwoven fabric. Specifically, by folding the laminated nonwoven fabric in half so that the back layers touch each other, and then passing it through a heat-sealing machine, the three-sided edges could be welded together without damaging or degrading the surface layer derived from the first nonwoven fabric.

[0034] Comparative Example A laminated nonwoven fabric was obtained using the same method as in Example 1, except that the mass ratio of core-sheath type composite short fibers to synthetic pulp was changed to core-sheath type composite short fibers:synthetic pulp = 100:0 to prepare the synthetic paper. The obtained laminated nonwoven fabric had a basis weight of 60 g / m². 2 , average pore diameter 12μm, air permeability 5cc / cm 2 / sec, moisture permeability 9000g / m 2 It was / 24hr.

Claims

1. It is a laminated nonwoven fabric consisting of three layers: a surface layer, an intermediate layer, and a back layer. The surface layer is made up of an aggregate of first-core-sheath type composite long fibers, the sheath component of which is made of high-density polyethylene and the core component of which is made of polyester having a melting point higher than that of the high-density polyethylene. The aforementioned intermediate layer is made of an aggregate formed by uniformly mixing core-sheath type composite short fibers, in which the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than that of the high-density polyethylene, with polyolefin-based synthetic pulp having a highly branched structure. The aforementioned back layer is made of an aggregate of second-core-sheath type composite long fibers, in which the sheath component is made of polyethylene and the core component is made of polyester having a melting point higher than that of polyethylene. The core-sheath type composite short fibers constituting the intermediate layer have a fiber diameter of 3 to 30 μm and a fiber length of 2 to 30 mm, and the polyolefin-based synthetic pulp has a fiber length of 0.1 to 5 mm. The three layers are characterized in that each layer is fixed and integrated by the softening, melting, and solidification of the sheath component of the first core-sheath type composite long fiber, the sheath component of the core-sheath type composite short fiber, the sheath component of the second core-sheath type composite long fiber, and the polyolefin-based synthetic pulp that constitute each layer.

2. The laminated nonwoven fabric according to claim 1, wherein the sheath component of the second core-sheath type composite long fiber is high-density polyethylene.

3. The laminated nonwoven fabric according to claim 1, wherein the sheath component of the second core-sheath type composite long fiber is linear low-density polyethylene.

4. A laminated nonwoven fabric according to any one of claims 1 to 3, wherein the average pore size is 1 to 9 μm.

5. The upper limit for breathability is an air permeability of 3.0 cc / cm². 2 The laminated nonwoven fabric according to any one of claims 1 to 3, wherein the air permeability is / sec and the lower limit of air permeability is an air permeability of 200 seconds / 100cc.

6. Moisture permeability of 4800-10000 g / m 2 A laminated nonwoven fabric according to any one of claims 1 to 3, wherein the hardness is 24hr.

7. A bag-like object formed by overlapping the back layers of the laminated nonwoven fabric described in claim 3 and welding the edges together.

8. A first nonwoven fabric comprising a first core-sheath type composite long fiber, in which the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than that of the high-density polyethylene, A synthetic paper comprising a core-sheath type composite short fiber in which the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than the melting point of the high-density polyethylene, and a polyolefin-based synthetic pulp having a multi-branched structure, wherein the fiber diameter of the core-sheath type composite short fiber is 3 to 30 μm and the fiber length is 2 to 30 mm, and the fiber length of the polyolefin-based synthetic pulp is 0.1 to 5 mm. A second nonwoven fabric comprising a second core-sheath type composite long fiber, in which the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than that of the high-density polyethylene. A method for manufacturing a laminated nonwoven fabric, comprising heating a laminate in the order of the first core-sheath type composite long fiber, the sheath component of the first core-sheath type composite short fiber, the sheath component of the second core-sheath type composite long fiber, and the polyolefin-based synthetic pulp, and then cooling to fix and integrate the first nonwoven fabric, the synthetic paper, and the second nonwoven fabric.

9. A first nonwoven fabric comprising a first core-sheath type composite long fiber, in which the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than that of the high-density polyethylene, A synthetic paper comprising a core-sheath type composite short fiber in which the sheath component is made of high-density polyethylene and the core component is made of polyester having a melting point higher than the melting point of the high-density polyethylene, and a polyolefin-based synthetic pulp having a multi-branched structure, wherein the fiber diameter of the core-sheath type composite short fiber is 3 to 30 μm and the fiber length is 2 to 30 mm, and the fiber length of the polyolefin-based synthetic pulp is 0.1 to 5 mm. A second nonwoven fabric comprising a second core-sheath type composite long fiber, in which the sheath component is made of linear low-density polyethylene and the core component is made of polyester having a melting point higher than that of the linear low-density polyethylene. A method for manufacturing a laminated nonwoven fabric, characterized by heating a laminate in the order of the first core-sheath type composite long fiber, the sheath component of the first core-sheath type composite short fiber, the sheath component of the second core-sheath type composite long fiber, and the polyolefin-based synthetic pulp to soften or melt them, and then cooling to fix and integrate the first nonwoven fabric, the synthetic paper, and the second nonwoven fabric.