JPH05125647A - Flexible laminated nonwoven fabric - Google Patents

Abstract

PURPOSE:To obtain the subject product comprising a sheet substrate composed of a specific fiber assembly and a film having sufficient bonding strength and suitable as flexible sanitary articles good in touch by laminating a thermoplastic resin film layer to the sheet substrate. CONSTITUTION:The objective product is obtained by laminating a film layer, composed of a polyolefinic thermoplastic resin having 5-25g/10min melt flow rate (MFR at 190 + or - 1 deg.C under 2160 + or - 10g load) and having 10-50mum thickness to a sheet substrate, composed of a fiber assembly containing 25-70wt.% meltable fiber component melting in laminating and having 70-250mum average distance (X) between fibers based on the formula [L is the thickness (cm) of the sheet substrate; W is the basis weight (g/mm<2>) of the sheet substrate; Di is the size denier of the sheet substrate fiber (i); alphai is the weight ratio (%) of the sheet substrate fiber (i)]. Core-sheath conjugate fiber composed of polyethylene as a sheath and polypropylene or a polyester as a core is preferred as the meltable fiber component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible laminated non-woven fabric in which a non-woven fabric and a film (resin layer) are integrally integrated, and is particularly suitable for sanitary products such as sanitary napkins and disposable diapers. The present invention relates to a laminated non-woven fabric having excellent adhesive strength.

[0002]

2. Description of the Related Art Laminating technology for adhering a polyolefin resin represented by polyethylene to a sheet base material such as paper or non-woven fabric is used for the purpose of protecting the contents from the outside world. It has been applied to various fields as food and industrial packaging materials. On the other hand, in sanitary napkins, disposable diapers and other sanitary products, due to the required characteristics of liquid-permeable surface materials (sometimes referred to as top sheet cover stock, outer packaging materials, etc.), they quickly absorb the liquid to be absorbed. A perforated hydrophobic film has been proposed as a material that gives a dry feeling to the user by transferring it to the body and not returning the liquid transferred to the absorbent body (Japanese Utility Model Publication No. 54-124398). 57-1340, Japanese Patent Publication 57-17081, etc.).

However, the flexibility and texture peculiar to the hydrophobic film are not always preferable for the user.
As a material that has a soft texture by controlling absorbency and reversion, and does not cause problems such as tearing during use, it is possible to apply laminated nonwoven fabric, but adhesive strength and flexibility are contradictory, that is, adhesion When the strength is increased, the laminated non-woven fabric becomes hard, and when it is made flexible, the sheet base material and the resin layer are easily separated, and there is a limit.

In order to satisfy both of these functions, Japanese Unexamined Patent Publication No. 63-28963 discloses partial pressure bonding.
Further, techniques such as multi-layering of resin layers have been proposed, but they have not been sufficiently satisfactory. Further, although the production conditions, the temperature, the amount of resin, and the like have been devised, their productivity is limited, and it is not always efficient to produce a product of constant quality.

Accordingly, an object of the present invention is to provide a sanitary article in which a sheet base material and a film have a sufficient adhesive strength and are soft and comfortable to touch in a composite sheet in which a thermoplastic resin is laminated on a sheet base material such as paper or nonwoven fabric. The purpose of the present invention is to provide a flexible laminated non-woven fabric suitable for.

[0006]

Means for Solving the Problems As a result of intensive studies for achieving the above object, the present inventors have found that the above object can be achieved by appropriately adjusting the number of adhesion points between a sheet base material and a thermoplastic resin. Knowing, the invention has been reached. That is, the present invention is
The molten fiber component that melts during lamination is 25 to 70
A sheet base material (hereinafter, referred to as a sheet base material) such as a paper or a non-woven fabric, which is a fiber aggregate including in the range of wt% and has an average interfiber distance (X) based on the following formula of 70 μm or more and 250 μm or less, Melt flow rate (MFR 190 ±
The thickness of the polyolefin resin is 5 to 25 g / 10 minutes at 1 ° C. and a load of 2160 ± 10 g) of 1
The object is achieved by providing a flexible laminated nonwoven fabric in which a thermoplastic resin film layer having a thickness of 0 to 50 μm is laminated.

[0007]

[Equation 2] Such a flexible laminated non-woven fabric has a porosity that specifically disperses regions (points) capable of adhering at a suitable density on the surface to be adhered to the thermoplastic resin film and allows the melted resin film to appropriately penetrate. And a thermoplastic resin film having a viscosity capable of appropriately penetrating into the sheet base material.

Hereinafter, the flexible laminated nonwoven fabric according to the present invention will be described in detail. The sheet base material in which the bondable regions of the present invention are dispersed can be used as long as it satisfies the following requirements (1) and (2) at the same time. (1) The sheet base material is a fiber assembly containing 25 to 70% by weight of a molten fiber component that melts during lamination.

The sheet base material is a fiber aggregate which can be fused by heat, and as the fibers constituting the sheet base material, the ratio of the molten fiber component which melts at the melting temperature of the thermoplastic resin film is important, 70% by weight, preferably 40-60
The one containing the weight% is good. When the ratio of the molten fiber component is less than 25% by weight, the flexibility is improved when laminated, but the adhesion between the sheet base material and the resin layer is deteriorated.

On the other hand, when the ratio of the molten fiber component is more than 70% by weight, the adhesion between the sheet base material and the resin layer is improved, but the bonding area is increased and therefore the flexibility is deteriorated, which is intended by the present invention. There is no. The molten fiber component here is a thermoplastic resin fiber component that can be heat-sealed at the time of laminating with a thermoplastic resin film, and is any thermoplastic resin fiber component having a melting point lower than the film resin temperature. good. As such a thermoplastic resin, ethylene, propylene, a polyolefin fiber mainly containing a monoolefin polymer and copolymer such as butene, a polyester fiber such as polyethylene terephthalate and polybutylene terephthalate, nylon 6, nylon 6,
Polyamide fiber such as nylon 66, polyvinyl chloride,
Polyvinyl fibers such as vinylidene, acrylic fibers, or composite fibers such as polyethylene / polypropylene, polyethylene or polypropylene, or low melting point polyester / polyester.

Wood pulp as a non-thermoplastic resin,
Natural fibers such as cotton, recycled fibers such as cupra and rayon, and semi-synthetic fibers such as acetate can be used. Furthermore,
A core-sheath type composite fiber (also referred to as Bicomponent) can also be preferably used. The core-sheath composite fiber here is composed of a resin that can be heat-sealed to the sheath (outer layer). In order to impart flexibility, it is preferable that the heat-sealed portion with the resin be as small as possible and that it have a strong adhesive force. In this respect, the composite fiber having a core-sheath structure can be preferably used, and particularly the sheath portion. Is polyethylene and the core is polypropylene or polyester, and the weight ratio of the core and the sheath is 30/70 to 70/3.
0 is the best. (2) The sheet base material has an average interfiber distance (X) based on the following formula of 70 μm or more and 250 μm or less.

[0012]

[Equation 3] The average inter-fiber distance X is for allowing the molten resin to penetrate to an appropriate depth and for dispersing the region (point) to be bonded to the thermoplastic resin, and an appropriate range is necessary for realizing the effect of the present invention. Is. That is, the average inter-fiber distance X is 70 to 250 μm, preferably 80 to 150 μm.
Is a non-woven sheet substrate.

The average inter-fiber distance X referred to here is defined by the following equation in consideration of a model in which all the fibers in the nonwoven fabric sheet base material are arranged in parallel at the inter-fiber distance X.

[0014]

[Equation 4] as well as

[0015]

[Equation 5] Then, from Equation 4 and Equation 5,

[0016]

[Equation 6] If the fineness of the fiber i is D _i denier and the basis weight of the nonwoven fabric is wg / m ² , then D _i = 900,000 a _i d
Equation 6 with _i and w = W / S / 10,000 (g / m ² ).
By substituting into, the following formula 7 can be derived.

[0017]

[Equation 7] Therefore, the average inter-fiber distance X is a function of the denier of the fiber, the basis weight of the sheet base material, the thickness of the sheet base material, and the weight percentage% of the fiber i of the sheet base material. When the fiber density is high and the average inter-fiber distance X is less than 70 μm, the resin melted in the film does not enter the fiber assembly, so that the adhesive strength is low and the resin layer is easily peeled off. Also, if it is forced in, it will go deep and will have a high adhesive force, but at the same time, its flexibility will be impaired. Even when the fiber density is low and the average inter-fiber distance X is larger than 250 μm, the melted resin deeply enters and impairs flexibility.

Fibers satisfying the scope of the present invention include 1
-6 denier, more preferably 1.5-4 denier in consideration of productivity and the like. A known technique can be used as a method for producing the sheet base material,
In order to obtain a softer laminated nonwoven fabric as described above, an air-through method in which fibers are uniformly dispersed and bonded with hot air can be preferably used in the present invention.
For example, as shown in FIG. 1, in the sheet base material, the above fiber components are sent out from between the winder 5 and the sheet roll 6 through the cotton blending machine 1, the card machine 2, the heat treatment device 3 and the embossing device 4 in this order. Created.

When used as a surface material for sanitary goods, a hydrophilic surfactant, which is a known technique for absorbing liquid, can be attached to the fibers. Further, known processing such as crimping or crimping of the fiber can be preferably used in the present invention. Next, the thermoplastic resin film has the characteristics (3) and (4).

(3) The thermoplastic resin film to be laminated is a polyolefin-based thermoplastic resin, which is JIS K-
6760 melt flow rate (MFR 190 ±
1 ° C., 2160 ± 10 g load) is 5 to 25 g / 10 minutes. The thermoplastic resin of the present invention has a melt flow rate of 5 to 25 g / 10 minutes, preferably 8 to 15 g / 10, so as to appropriately penetrate into a sheet base material satisfying the requirements of the present invention.
Minutes are good.

The resin to be laminated is ethylene,
Polyolefin resin mainly composed of propylene and monoolefin polymers and copolymers such as butene has flexibility,
It is preferable for stability of productivity, cost, and quality at the time of manufacturing, and more preferably has a density of 0.900 to 0.940.
Ethylene, propylene, butene-1, pentene-
Polymers and copolymer resins containing α-olefin as the main component such as 1 are preferable.

Inorganic and organic fillers may be added to these thermoplastic resins. As the inorganic filler, calcium carbonate, gypsum, talc, clay, kaolin, silica, diatomaceous earth, magnesium carbonate, barium sulfate, calcium phosphate, aluminum hydroxide, zinc oxide, titanium oxide, alumina, mica, zeolite, carbon black and the like. Used as the organic filler are pulp powder, starch and the like. These may be used alone or in combination.

(4) The thickness of the thermoplastic resin film layer to be laminated is 10 to 50 μm. The thickness of the thermoplastic resin film layer of the present invention is 10 to 5 so as to have a heat capacity necessary for melting an appropriate amount of the molten fiber component of the sheet base material.
A thickness of 0 μm is good. More preferably, it is 15 to 40 μm.

In the laminating process, as shown in FIG. 2, the molten resin film layer 11 and the sheet base material 12 from the melt extruder 10 provided on the upper portion are combined with the pressure roll 1.
It is possible to use a general laminating machine such as one that feeds between 3 and the chill roll 14. As shown above, the flexible laminated nonwoven fabric of the present invention can be suitably used for hygiene products if the above requirements (1) to (4) are satisfied. Adhesive strength of 70 g / 25 mm width or more in the MD direction and a soft texture can be obtained by the method described in Examples below.

[0025]

[Effect] The laminated non-woven fabric of the present invention has a structure in which the fibers themselves of the sheet base material are freely entangled or bonded at the entanglement point by heat, and thus have a relatively large degree of freedom, so that the non-woven fabric is soft and has a good texture. Becomes Further, in the adhesion between the sheet base material and the thermoplastic resin for the film, since the viscosity and the fluidity of the thermoplastic resin for the film when melted are constant, and the average inter-fiber distance of the fibers of the sheet base material is constant. Therefore, the depth of impregnation into the sheet base material of the thermoplastic resin for film is set appropriately, and since the molten fiber component of the sheet base material is contained in a certain amount, the area (volume) that can be bonded to the film resin is set appropriately. Therefore, the regions (points) where the sheet base material and the film can be adhered can be appropriately scattered. That is, since the number of point bonds with the thermoplastic resin for film is appropriately formed at the time of laminating, it is possible to obtain a laminated non-woven fabric which is flexible and has a sufficient adhesive force and which is suitable for sanitary goods. ..

[0026]

EXAMPLES The present invention will be specifically described below with reference to examples. The present invention is not limited to these examples. A. Preparation of Laminated Nonwoven Fabric Various kinds of laminated nonwoven fabrics relating to the present invention or comparative laminated nonwoven fabrics having the constitutions shown in Tables 1 and 2 were prepared by the following known methods, and their performances were evaluated by the following methods. Each physical property value is an average value of 10 measured values.

The non-woven fabrics of Examples 1 to 7 and Comparative Examples 4, 5 and 8 were produced by the air-through method as shown in FIG.
It was prepared by heat treatment at 10 ° C. for 10 seconds. Comparative Examples 1 to 3 were prepared by thermocompression bonding with a hot embossing roll. Comparative Examples 6 and 7 used spunbond nonwoven fabrics. These sheet base materials are melt-extruded and laminated as shown in FIG. 2 and the extruded resin temperature is 300 ° C. and the sheet base material speed is 80 m /
Laminated in minutes.

B. Constituent Materials (1) Sheet Base Material (Nonwoven Fabric) Basis Weight (wg / m ² ) The weight of a fiber layer having a size of 200 mm × 250 mm was measured to calculate the basis weight. Thickness (Lcm) A set of 10 test pieces cut into 100 mm × 100 mm squares was used. The measurement was performed using Tensilon RTM-25 type (manufactured by Orientec Co., Ltd.). First, as shown in FIG. 3A, the pressure receiving plate 20 of the compression 5 kg load cell is gently brought into parallel contact with the sample table 22 and a load of 1 g is applied. The distance between the pressure receiving plate 20 and the sample table 22 at this time is 0 cm.
Then, the pressure receiving plate 20 is raised by 5 cm. Next, 10 stacked test pieces are placed on the sample table 22 (shown in FIG. 3B), the pressure receiving plate 20 is lowered and the load applied to the test piece is recorded on a recording paper, and 1 g is applied to the test piece. The displacement d (cm) of the pressure receiving plate 20 until the load is applied is read (shown in FIG. 3C). Therefore, the thickness L (cm) is calculated by the following formula.

L = (5-d) / 10 The measurement conditions are as follows. Pressure receiving plate descending speed: 3 mm / min Recording paper full-thurs: 50 g Recording paper scanning speed: 30 mm / min (2) Film thickness (Tμm) The cross section of the laminated non-woven fabric was photographed as shown in the photograph imitation drawing of Fig. 4, and on the photograph Was measured using a ruler, and the actual thickness T (μm) was calculated by the following equation.
T = 1000 × t / k (k is magnification of photograph) Physical properties of laminated nonwoven fabric Melt flow rate (MF) described in JIS K-6760
R 190 ± 1 ℃, 2160 ± 10g load)
Measure FR.

C. Evaluation of laminated non-woven fabric Adhesive strength Laminated non-woven fabric (sheet base material 30 and film 32)
On both sides of the cloth tape 34, 35 (Sekisui Chemical Co., Ltd. N
o. 600) is attached and the width is 25 mm as shown in Fig. 5 (a),
A test piece having a length of 175 mm in the MD direction (machine flow direction) is prepared. The cloth tape 34 on the film layer side has an adherable portion of 150 mm, and a slit 36 is lightly formed in the film.

The measurement was carried out using a Tensilon RTM-25 type (manufactured by Orientec Co., Ltd.) as shown in FIG. 5 (b).
A peel test was performed. The measurement conditions are as follows. Load cell used: 5kg Distance between chucks: 5mm Peeling speed: 300mm / min Recording paper scanning speed: 100mm / min Recording paper full scale: 500g Peel strength is the peeling end of the tensile load recorded on the recording paper as shown in Fig. 6. Calculated from the tensile load between 60 mm and 20 mm from the point. As the calculation method, 5 points were extracted from the one having a large tensile load and 5 points were extracted from the one having a small tensile load, and the average value was taken as the peel strength. Texture The laminate composition was evaluated by the feel of 5 panelists when the surface was lightly stroked or lightly gripped.

◯: All were judged to be good Δ: 3 to 4 were judged to be good ×: 3 or more were judged to be bad

[0033]

[Table 1]

[0034]

[Table 2] L-LDPE: Linear low density polyethylene LDPE: Low density polyethylene Ionomer: High Milan (Mitsui Polychemical Co., Ltd.)
Made by: PP: polyethylene PET: polyethylene terephthalate PE: polyethylene D.I. Evaluation results As shown in Examples 1 to 7, the laminated nonwoven fabric of the present invention has a soft texture that can be suitably used for hygiene products, and has a sufficient adhesive force of 70 g / 25 mm width or more in the MD direction. Obtainable.

On the other hand, in Comparative Examples 1 to 3, 7 and 8, the proportion of the molten fiber component is 25% by weight or less, and when laminated, the flexibility is improved, but the adhesion between the sheet base material and the resin layer is deteriorated. .. In addition, since the distance between the fibers is smaller than 70 μm, the molten resin does not enter the fiber assembly, so that the adhesive strength is low and the resin layer is easily peeled off.
Further, as in Comparative Examples 2 and 7, when the resin is attempted to enter into the fiber assembly, it deeply enters and has a high adhesive force, but the flexibility is impaired.

Therefore, it was considered that all of the examples shown as comparative examples were extremely insufficient for use in hygiene products.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an apparatus for manufacturing a sheet base material.

FIG. 2 is an explanatory diagram of a laminating process.

3 (a) and 3 (b) are explanatory views of an apparatus for measuring the displacement of the thickness of the sample piece with respect to a constant load, and FIG. 3 (c) is a graph showing the relationship between the displacement and the load by the apparatus.

FIG. 4 is a photographic imitation of a cross-sectional photograph of a flexible laminate according to the present invention.

5A and 5B are a perspective view and a cross-sectional view of a sample piece used for measuring an adhesive force.

FIG. 6 is a graph showing a relationship between a peeling length and a load in measuring an adhesive force.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cotton mixing machine 2 Card machine 3 Heat treatment apparatus 4 Embossing apparatus 5 Winder 6 Sheet roll 10 Melt extruder 11 Molten resin film layer 12 Sheet base material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location B32B 5/08 7016-4F 27/12 7258-4F D06M 15/00 D06M 15/00

Claims (1)

[Claims] 1. A fiber assembly containing a molten fiber component that melts during lamination in the range of 25 to 70% by weight,
In addition, a sheet base material having an average inter-fiber distance (X) based on the following formula of 70 μm or more and 250 μm or less, and a polyolefin resin having a melt flow rate (MFR 190 ± 1 ° C., 2160 ± 10 g load) of 5 to 25 g / 10 min. A flexible laminated non-woven fabric comprising a thermoplastic resin film layer made of a thermoplastic resin and having a thickness of 10 to 50 μm. [Equation 1]