JPH1018154A - Laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laminate useful for a house wrapping material, excellent in mechanical strength and water resistance without causing delamination by laminating a specific sheath-core type filament nonwoven fabric to a synthetic paper of wet papermaking containing a polyolefin-based synthetic pulp. SOLUTION: This laminate is obtained by laminating (A) a sheath-core type filament nonwoven fabric comprising an aromatic polyester as a polyethylene terephthalate as a core component and a polyethylene as a sheath component to (B) a synthetic paper of wet papermaking containing a polyolefin-based synthetic pulp. Preferably, the laminate has >=800mmH2 O water resistance, <=120 seconds air permeability and 60-90 opacity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a laminate comprising a composite long-fiber nonwoven fabric and a wet papermaking synthetic paper. More specifically, the present invention relates to a laminate having excellent water resistance, appropriate translucency, and air permeability.

[0002]

2. Description of the Related Art Conventionally, polyethylene, polypropylene,
Nonwoven fabrics made of long fibers from synthetic resins such as polyester and polyamide are used in various fields as spunbonded nonwoven fabrics. These spunbonded nonwoven fabrics have high strength and air permeability even if they are thin compared to other nonwoven fabrics, so they can be used for agricultural materials, civil engineering materials, various sanitary materials, construction materials, daily necessities, medical supplies, etc. Widely used for materials for use. Nonwoven fabrics formed from these synthetic resin long fibers are generally hydrophobic and are not suitable for fields where water absorption and moisture absorption are required.

[0003] On the other hand, wet papermaking and nonwoven fabrics obtained from natural or synthetic pulp or short fibers are dense and uniform and have excellent concealing properties. In particular, papermaking and nonwoven fabrics containing natural pulp and rayon staple fibers are hydrophilic,
Excellent hygroscopicity. However, such papermaking cannot be said to have sufficient strength, and particularly, the strength when wet is low. Various composite papers have been proposed in which a long-fiber nonwoven fabric made of the above-mentioned synthetic resin and papermaking are laminated to combine these advantages. For example, JP-A-5-279
No. 997 discloses a spunbonded nonwoven fabric having a core-sheath structure and a sheath portion containing a heat-fusible resin fiber having a lower contact point than the core portion, and a continuous or discontinuous wet-papermaking method on the nonwoven fabric surface. A composite paper comprising a papermaking layer laminated and formed on the nonwoven fabric and the papermaking layer, wherein the nonwoven fabric and the papermaking layer are joined via a low-melting-point heat-meltable resin in a sheath portion of the spunbonded nonwoven fabric. Composite paper. And JP-A-8-52843 discloses that "a nonwoven fabric made of continuous synthetic continuous fiber formed by a spunbond method and a paper sheet made of wood pulp are laminated, and the synthetic fiber and the pulp fiber are A packaging material in which any one surface of a first sheet layer made of an entangled and integrated composite nonwoven fabric is joined to a second sheet layer made of a polyolefin-based synthetic resin film. 』
Is described.

[0004] In any of the laminated materials proposed above, papermaking in which one layer uses natural pulp is used. These laminated materials are superior in strength as compared with papermaking and long-fiber nonwoven fabric, and also have improved concealing properties, hydrophilicity and hygroscopicity. However, since the papermaking layer of natural pulp is used as it is, delamination is likely to occur, and the natural pulp may be generated as a powder during use. Such generation of paper dust is not desirable for use in a medical field such as surgical gowns or in a clean room.

[0005] On the other hand, a non-woven sheet composed of composite filaments comprising a low melting point thermoplastic resin A such as polyethylene and a high melting point thermoplastic resin B such as polyethylene terephthalate, wherein the B component is in the form of a filament in the entire surface of the sheet. The composite non-woven sheet in which the component A is in an irregular shape and is distributed over the entire surface of the sheet is disclosed in
No. 33644, which is a non-woven sheet formed of a composite long fiber having polyethylene as a sheath component and polyethylene terephthalate as a core component, which is partially thermally pressed at a temperature equal to or lower than the melting point of polyethylene. Adhesive non-woven sheet keeping the typical shape
No. 069 has been proposed. The non-woven sheets described in the above two publications are non-woven sheets made of a composite long fiber having polyethylene as a sheath component and polyethylene terephthalate as a core component. Is a sheet that has been partially hot pressed,
Each of them lacks dense uniformity. In addition, both are made of a thermoplastic synthetic resin and do not have hydrophilicity or hygroscopicity.

[0006]

Therefore, the first aspect of the present invention
The purpose of the present invention is to keep the advantages of a laminate of a long-fiber nonwoven fabric made of synthetic fibers and a wet-laid synthetic paper containing pulp while preventing peeling, and having an appropriate opacity and an appropriate air permeability. It is another object of the present invention to provide a laminated body which has strength against water. Further, the second aspect of the present invention
An object of the present invention is to provide various types of nonwoven fabric laminates that can be used in a wide range of fields.

[0007]

According to the study of the present inventors, the object of the present invention is to provide (A) a core-sheath type long-fiber nonwoven fabric comprising an aromatic polyester as a core component and polyethylene as a sheath component; (B) It is achieved by a laminate obtained by laminating a wet papermaking synthetic paper containing a polyolefin synthetic pulp and substantially not causing delamination at the interface between them.
The laminate of the present invention has an A-layer in which a long-fiber nonwoven fabric made of a conjugate fiber in which a core component is an aromatic polyester and a sheath component is polyethylene is an A layer, and a wet synthetic paper containing a polyolefin-based synthetic pulp is a B layer. It is a B-type laminate, and the polyethylene component of the A layer and the polyolefin component of the B layer are bonded together by heat at the interface between the two layers to be integrated. In this lamination, the A layer and the B layer may be any of AB type, ABA type, or BAB type.

[0008] The long-fiber nonwoven fabric constituting the laminate of the present invention is formed of a core-sheath type conjugate fiber, and the core component is an aromatic polyester. As the aromatic polyester, those having a fiber-forming ability, particularly those used as fibers, are preferable. Specifically, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate or a copolymer having these as a basic skeleton is preferred. Polymerized polyesters are exemplified. Particularly preferred are polyesters in which ethylene terephthalate units or butylene terephthalate units account for at least 80 mol%, preferably at least 85 mol%, of all repeating units. Examples of the acid component that can be copolymerized include isophthalic acid, adipic acid, and sebacic acid, and examples of the glycol component include hexamethylene glycol, diethylene glycol, and triethylene glycol.

[0009] The polyethylene forming the sheath component of the conjugate fiber may be any one usually used as a material of a fiber or a film, and has a density of 0.910 to 0.925.
Low density polyethylene; density between 0.926 and 0.940 medium density polyethylene; and density between 0.941 and 0.96
5 high density polyethylene. Among them, those which are commercially available as linear low-density polyethylene obtained by copolymerizing ethylene with an α-olefin having 4 to 8 carbon atoms have a spinnability and a texture when formed into a nonwoven fabric. This is particularly preferred from the viewpoint of:

The ratio of the core component to the sheath component in the composite fiber is 80:20 to 20:80 by weight, preferably 75:20.
It is in the range of 25 to 25:75, the shape of the core may be substantially circular or slightly modified, and the core may or may not be eccentric in the cross section of the fiber.

The fineness of the conjugate fiber is usually in the range of 1 to 5 de, preferably 1.5 to 4.5 de, and a nonwoven fabric is formed from the core-sheath type conjugate fiber by a spunbonding method known per se. The nonwoven fabric is formed by crimping so that the sheath components are bonded to each other. The basis weight of the long-fiber nonwoven fabric (layer A) is 10 to 70 g / m ² , preferably 20 to 60 g.
/ M ² is appropriate. If the basis weight is smaller than this range, the strength of the laminate will be insufficient, while if the basis weight exceeds this range, the whole will be hard, the air permeability will be low and the texture will be impaired.

The long-fiber nonwoven fabric (Layer A) is laminated with a synthetic paper (Layer B), which will be described later, and when thermocompression-bonded, it shrinks due to the temperature during the operation and loses the smoothness of the laminate. May be asked. Therefore, it is preferable to shrink in advance according to the following method, and use it as a low-shrinkable long-fiber nonwoven fabric. That is, (i) a core-sheath type long fiber having an aromatic polyester as a core component and polyethylene as a sheath component is spun to produce a composite long fiber, and (ii) the obtained long fiber is collected on a moving net. To form a web, (ii
i) Temporarily fixing the web with a heating roller at 80 to 100 ° C,
(Iv) Then, it is passed through a hot atmosphere at 150 to 180 ° C. to shrink it, and (v) further thermocompression-bonded with a heating roller at 130 to 140 ° C. to obtain a low-shrink composite long-fiber nonwoven fabric. Thus, the obtained nonwoven fabric is
Heat shrinkage (area shrinkage) at 130 ° C. is 2% or less,
It is preferably 1% or less, and is suitable for laminating with synthetic paper (layer B).

In the laminate of the present invention, the papermaking synthetic paper (layer B) laminated with the long-fiber nonwoven fabric (layer A) is a wet papermaking containing a polyolefin-based synthetic pulp. That is, the layer B is papermaking using a polyolefin-based synthetic pulp. This pulp is obtained, for example, by flash spinning of a polyolefin solution or emulsion. There is also a method in which a polyolefin and a water-soluble polymer are mixed and spun to obtain short fibers, and then beating treatment is performed. Examples of the polyolefin include ethylene and α-olefins such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-1-butene copolymer, and ethylene-4-methyl-1-pentene copolymer.
Polyolefins, such as copolymers of two or more species, are preferred. Above all, crystalline polyolefins
It is desirable for producing a pulp-like material and for mechanical properties of the obtained pulp-like material.

This synthetic pulp is a long-fiber nonwoven fabric (layer A)
Is thermally fused to the sheath component, whereby the laminate of the present invention is extremely excellent in strength. Also, papermaking
Synthetic pulp can be formed alone, but it is also possible to make paper in combination with synthetic fibers and / or natural pulp, as long as the strength-improving action by heat fusion is not impaired. Generally, synthetic pulp exhibits sufficient strength when used in a proportion of at least 5% by weight, preferably 10% by weight or more, and the amount of synthetic fibers and natural pulp used is 95% by weight or less, preferably 70% by weight. % Is desirable. When the synthetic paper (layer B) is formed of 100% synthetic pulp, the surface becomes extremely smooth. When natural pulp is used together with synthetic pulp, the surface of the synthetic paper has a paper texture. Further, when synthetic fibers or natural pulp are used in combination, the synthetic paper has excellent air permeability.

The synthetic fiber is preferably made of a polymer having a melting point higher than that of the synthetic pulp, and usually has a fiber length of 1 to 50 mm, particularly 2 to 20 mm, and a fineness of 1 to 1.
Those having 5 de, especially 1.5 to 4.5 de are preferably used. Further, a sheath-core type composite fiber having a core portion having a high melting point and a sheath portion having a low melting point can also be used. In this case, the lower melting point is lower than the melting point of the synthetic pulp, and the higher melting point is higher than the melting point of the synthetic pulp. The natural pulp is a pulp made from a material containing natural cellulose, and is typically a wood pulp. The basis weight of the wet papermaking synthetic paper (layer B) is usually ^{2 to} 100 g / m ² , preferably 3 to 70 g / m ² .

The lamination ratio of the A layer and the B layer can be changed depending on the purpose and application, but is generally 70:
30-30: 70, preferably 65: 35-35: 65
Is desirable.

The layers A and B are integrated by fusing the sheath component of the conjugate fiber and the polyolefin in the papermaking layer, respectively. Therefore, the laminate is composed of a papermaking layer (layer B) and a nonwoven fabric layer (layer A). ) Are firmly adhered through the interface and are not easily separated. Also, the laminate may get wet with water,
Even when wet, the strength does not drop significantly.
The lamination and integration of the layer A and the layer B are usually performed by thermocompression bonding, but may be performed by either full pressure bonding or partial pressure bonding. The temperature is 30 ° C. or more lower than the melting point of the polyester forming the core component in the conjugate fiber, and is preferably 150 ° C.
Temperatures below ℃ are suitable. Generally, 100 to 135
C. is preferred.

The temperature, pressure and time in the thermocompression bonding are correlated with each other, and preferable conditions and means are selected depending on the type and combination of the papermaking layer and the nonwoven fabric layer to be used, the intended use of the laminate, and the like. The laminate according to the present invention,
Does not transmit water, and has a water resistance of 800 measured by the method described below.
mmH2O or more, preferably 1100 to 1400 mmH2
Since it has a range of O, even if it comes into contact with water or rain, it does not easily penetrate, and the strength does not decrease.

Furthermore, the laminate of the present invention has an appropriate air permeability and can be used for wrapping, agricultural sheets, food packaging and the like in fields where ventilation is desired. The air permeability is
An appropriate time is 120 seconds or less, preferably 20 to 100 seconds. Also, preferably, the laminate of the present invention can be easily provided with transparency that is maintained to some extent and that is not completely opaque. This opacity can be in the range of 60 to 90, preferably 70 to 85, as measured by the measurement method described below. This opacity or translucency means that, for example, when the laminate is used as a wrapping material for a building or a house (house wrapping material), columns, pillars,
It is the range where the position and existence of the frame and the steel frame can be visually checked.

[0020]

The laminate of the present invention has high strength, excellent water resistance, does not easily transmit water, and has appropriate air permeability. It is advantageously used as a material. For example, it is suitable for house wrapping, agricultural fields, and the like.

[0021]

The method of the present invention will be described below in detail with reference to examples. In the examples, water resistance, opacity and air permeability are values measured according to the following methods. (I) Water resistance Measured according to JIS 611 6.6. (Ii) Opacity It was measured according to JIS P8138. (Iii) Air permeability 100 cc of gas measured according to JIS P8117
Is the transmission time (seconds). (Iv) Measured according to JIS P8116.

Example 1 (Preparation of Layer A) Polyethylene terephthalate (intrinsic viscosity: 0.6) was used as a core component, melted at 290 ° C., and a linear low density polyethylene (MFR20) was used as a sheath component.
Was melted at 220 ° C. Then, the mixture was discharged at a spinning temperature of 280 ° C. from a spinning head having 10 core-sheath composite spinnerets having 100 holes. After discharging, while cooling by cooling air, 5 ejectors arranged under the base
The fiber was drawn at a speed of 000 m / min and opened. After the opened yarn was collected on a moving conveyor net to form a web, the web was temporarily fixed with a roll heated to 90 ° C. Further, after passing through a hot air atmosphere of 150 ° C.,
The web is thermocompressed with an emboss calendar at 130 ° C.,
A long-fiber nonwoven fabric with a basis weight of 20 g / m ² was obtained. The thickness of the fibers constituting the nonwoven fabric was 1.5 denier, and the core / sheath ratio was 60/40.

(Preparation of Layer B) Polyethylene synthetic pulp 8
0% by weight and 20% by weight of 2 denier short fiber having a core of polyethylene terephthalate and a sheath of acid-modified polyethylene and a fiber length of 5 mm are dispersed in water, and a paper layer is formed by wet papermaking. It was dried with a Yankee dryer to obtain synthetic pulp. The basis weight was 20 g / m ² . (Lamination) The long-fiber nonwoven fabric and the synthetic pulp paper were laminated, and the surface heated to 130 ° C. was thermocompressed with a flat metal roll. Table 1 shows the lamination method and the water resistance, air permeability, tear strength and opacity of the obtained laminate.

Example 2 The ratio of synthetic pulp and short fibers forming the layer B was 60/40.
A long-fiber nonwoven fabric and a synthetic pulp paper were obtained in the same manner as in Example 1 except that these were laminated, and these were laminated and thermocompression-bonded with a flat metal roll heated to 130 ° C. Table 1 also shows the lamination method and the water resistance, air permeability, tear strength and opacity of the obtained laminate.

COMPARATIVE EXAMPLE 1 Three long-fiber nonwoven fabrics of Example 1 were laminated and thermocompression-bonded with a flat metal roll heated to 130 ° C. Table 1 also shows the lamination method and the water resistance, air permeability, tear strength and opacity of the obtained laminate.

Comparative Example 2 A basis weight of 6 was prepared by the same method as that of the synthetic pulp paper of Example 1.
A synthetic pulp paper of 0 g / m ² was obtained, and this was heated to 130 ° C. and hot-pressed with a flat metal roll. Table 1 also shows the water resistance, air permeability, tear strength, and opacity of the obtained pressed body.

[0027]

[Table 1]

Examples 1-2 and 2-2 are particularly excellent in water resistance and are useful for house wrap applications. In addition, Examples 1-1, 2-1 and 2-3 have water resistance and appropriate air permeability, and are useful as fruit packaging materials. Comparative Example 1 is excellent in strength but has difficulty in water resistance. Also,
Comparative Example 2 has sufficient water resistance, but has drawbacks in terms of air permeability and strength.

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Claims (5)

[Claims] 1. A laminate obtained by laminating (A) a core-sheath type long-fiber nonwoven fabric having an aromatic polyester as a core component and polyethylene as a sheath component and (B) a wet papermaking synthetic paper containing a polyolefin-based synthetic pulp. A laminate that does not cause delamination at the interface between the two. 2. The laminate according to claim 1, having a water resistance of 800 mmH ₂ O or more. 3. The laminate according to claim 1, which has an air permeability of 120 seconds or less. 4. An opacity of 60 to 90.
4. The laminate according to any of 3. 5. A house wrapping material using the laminate according to claim 1.