JPS62144931A - Preparation of composite sheet - Google Patents

Abstract

PURPOSE:To obtain a composite sheet exhibiting good adhesiveness without spoiling air permeability and flexibility of a porous sheet and a reinforcing material by heat-pressing a porous sheet and a reinforcing material through a powder adhesive. CONSTITUTION:This invention gives a method for preparing a composite sheet by heat-pressing a porous sheet and a reinforcing material through a powder adhesive. For the porous sheet of this invention, a porous sheet prepared by drawing a sheet composed of 100pts.wt. of a polyolefin resin, 50-400pts.wt. of a filler and, if necessary, a softener, etc., having a thickness of 10-50mu, a max. pore diameter of smaller than 2mu, air permeability of 50-2,000sec/100cc and moisture permeability of 2,500-5,000g/m<2>.24hr and having excellent flexibility, moisture permeability and strength, is preferably used. For the reinforcing material, it is preferable that its pore size is larger than that of the porous sheet. In general, such sheet-like reinforcing materials as film-like sheets having flat-shaped pores, non woven fabrics of woven fabrics are used. For the quantity of the powder adhesive scattered, 3-30g/m<2> based on the porous sheet or the reinforcing material are preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for manufacturing a composite sheet, and more particularly to a porous sheet and a reinforcing material, in which a reinforcing material is thermocompression bonded to a porous sheet via a powder adhesive. To provide a simple method for manufacturing a composite sheet with improved adhesiveness and air permeability and moisture permeability without impairing physical properties such as air permeability and flexibility.

(Prior art and its problems) Generally, polyolefin resin is filled with an inorganic filler of 40% or more, and after being formed into a sheet, this is
A porous sheet can be obtained by axial or biaxial stretching. The polyolefin porous sheet prepared in this way has a unique texture and has a feel similar to paper or leather without the sticky feeling characteristic of synthetic resins. Furthermore, such porous sheets have excellent air permeability and moisture permeability, do not cause dew condensation, and are water-wettable, so they are suitably used for wallpaper, breathable and water-wettable packaging sheets, and the like. Recently, porous sheets have been improved by adding flexibility to their excellent properties, and adding reinforcing materials to give them mechanical strength and functionality.
For example, diaper covers, back sheets for disposable diapers,
It is expected to be used in fields such as base materials for adhesive patches, medical hygiene materials such as rain gutters and hospital sheets, and simple clothing.

As a method of laminating a reinforcing material on a porous sheet as described above, for example, a method of thermo-compression bonding the porous sheet and the reinforcing material or a method of pasting the reinforcing material using a solvent type adhesive has been proposed. However, in the method of thermocompression bonding a porous polyolefin sheet and a reinforcing material, it is difficult to adjust air permeability (porosity) due to the 7M degree of the thermocompression machine and minute fluctuations in pressure, and the resulting composite sheet has poor mechanical strength. has been improved and 'C
However, flexibility and breathability may be impaired or have widely variable drawbacks. In addition, when pasting with adhesive, the adhesive (solvent) bleeds through the holes in the reinforcing material, resulting in the adhesive roll becoming dirty, and the adhesive film reducing air permeability and moisture permeability. It has the disadvantage of being industrially complicated, as it tends to cause extensive deterioration and also requires equipment for removing harmful substances from the solvent.

(Means for solving the problem) In order to solve the above problem, the present inventors have developed a composite sheet that can easily exhibit adhesive properties without impairing the air permeability and flexibility of the porous sheet and reinforcing material. As a result of various studies aimed at achieving this goal, we have achieved the desired goal by using a method of thermocompression bonding using a powdered adhesive, and have come to propose the present invention. That is, the present invention is a method for manufacturing a composite sheet, which is characterized by thermocompression bonding a porous sheet and a reinforcing material via a powdered adhesive.

The porous sheet of the present invention is, for example, a stretched sheet made from an M1 composition of synthetic resin containing a filler, a sheet in which holes are mechanically formed in the stretched sheet, or the stretched sheet. A porous sheet produced by a known manufacturing method, such as a sheet obtained by extracting a filler from a porous sheet, can be used without particular limitation. Among these, polyolefin resin 1°0 weight 1! ! : parts by weight of filler, 50 to 400 parts by weight of filler, and if necessary, a softener, etc. The sheet-like material is stretched to have a 1:I thickness of 10 to 50,011 parts.
% maximum pore diameter 211 or less, air permeability 50-20oo seconds/1
00 (2C (by Gurley method), moisture permeability 2F500~5
000 g/m' ・24Hr (4,0℃X90%R
A porous sheet with excellent flexibility, moisture permeability, and strength (based on the H moisture permeable cup method) is preferably used in the present invention.

As the polyolefin resin used in the above-mentioned porous sheet, homopolymers or copolymers of olefins such as ethylene and propylene can be used without particular limitation, and among them, high-density polyethylene is used.

Medium and low-j polyethylene, called medium-density polyethylene and linear low-density polyethylene, are preferred, especially those with a density of 0.
．． Melt flow index at 910-0.514.0g/mark 3, 7. Linear low-density polyethylene having a (MFR) of 0.1 to 10 g/10 min, preferably 0.1 to 5 g/10 min, is preferably used to obtain a porous sheet having flexibility and good air permeability. It is also preferable to mix two or more of the above polymers or copolymers;
In particular, copolymers of ethylene and other α-olefins having a crystalline polyolefin resin with a degree of oxidation of 5 to 25% and a density of 0.86 to 0.90 g/mark 3 by X-rays,
When using a mixed resin consisting of a blend of 1 (also referred to as a soft resin), the resulting porous sheet has even more flexibility without impairing its moisture permeability, so it has particularly high tensile strength and tear strength. Excellent in Therefore, in order to obtain a more flexible composite sheet, it is preferable to use a porous sheet in which the above-mentioned soft resin is generally blended at a ratio of 20 to 100 parts by weight per 100 parts by weight of the crystalline polyolefin resin.

In addition, the filler used for the above-mentioned porous sheet is not particularly limited, but inorganic fillers that are usually mixed into rubber or plastics, such as lucium carbonate, stone cubes, calcium finger sulfate, calcium phosphate, and magnesium carbonate, may also be used. , basic magnesium carbonate, magnesium sulfate, hydrated silicic acid, silicic anhydride.

Soda ash, sodium chloride, barium sulfate, clay, various cements, fire 111 ash, whitebait, titanium oxide.

Iron oxide, carbon black, various metal powders, and other inorganic substances or S! It is generally used as a powder having an average particle diameter of 50μ or less, preferably 0.05 to 0.05μ, particularly about 0.1 to 5μ.The average particle size of such a filler is If the diameter is too large, the density of the pores in the resulting porous sheet will be reduced, and if the average particle diameter is too small, the stretched sheet will generally be uneven, making it difficult to obtain a good porous sheet.

The blending ratio of the filler is generally 50 to 114)00 parts by weight, particularly 60 to 300 parts by weight, based on 00 parts of polyolefin resin.
00 weight paper part is preferable; on the other hand, if it is less than 50 weight part, the resulting porous sheet will have fewer communicating pores, resulting in low moisture permeability, and on the other hand, 400 weight part.

If the amount is too large, it becomes difficult to form and stretch a sheet-like product.

Furthermore, in the production of the porous sheet, a conventional mixing method is used to mix the filler with the polyolefin resin. In mixing such a polyolefin resin composition, small amounts of stabilizers, pigments, stearic acid and metal salts thereof, and silicone oil for imparting fluidity and water resistance may be mixed simultaneously or separately.

Next, a porous sheet can be obtained by obtaining a sheet-like product from the polyolefin resin composition, generally by extrusion molding, and then stretching it by a conventional method. Note that the thickness of the porous sheet in the present invention does not have a strict meaning, and is generally lθ to 500 ml.

The reinforcing material used in the present invention preferably has a pore diameter larger than that of the porous sheet, and is generally a flat perforated film sheet or nonwoven fabric.

Alternatively, a sheet-like reinforcing material such as woven fabric is used.

For example, fine cloth made from split yarns or flat yarns drawn from resin Filno, nonwoven fabrics made by dry, wet, or spunbond methods, or flat perforated film-like sheets such as woven fabrics and perforated plastics. And in this, flexibility.

In order to produce a good composite sheet of the present invention that balances air permeability, moisture permeability and strength, non-woven fabrics and woven fabrics are preferred.

In particular, the reinforcing material in the present invention is made of polypropylene, nylon, Tetron, rayon, etc. with a pore diameter of 10 to 50.
(,) It, Flexibility 50mm or less, Tsubo*] 0~10
0 g/yri' non-woven fabric or woven fabric, maximum pore diameter 2μ or less, flexibility 30mm or less, thickness 20-6011
, moisture permeability 2500~F5000 g/m'・24
Ht”.

By laminating it with a porous sheet of linear low-density polyethylene having an air permeability of 1511'50 to 7100 cc for 2000 seconds, a composite sheet suitable for the aforementioned medical sanitary materials 1; 1, simple clothing, etc. can be obtained. In addition, the reinforcing film resin generally includes polyolefins such as polyethylene and polypropylene, polyvinyl alcohol,
Polyethylene terephthalate, polyamide, polyvinyl chloride, or copolymers and mixtures thereof are used.

In the present invention, the flexibility is such that the effect is exhibited every day.

In the production of breathable and strong composite sheets, the flexibility of the porous sheet used (a 50 mm wide sheet is taken out from the edge of a horizontal table, and the vertical sagging distance is 2 (
The length of the sheet protruding from the edge of the stand when it becomes 1 mm (expressed in mm): Use a porous sheet with a maximum pore size of 30 or less and a maximum pore diameter of 2), and a reinforcing material with a flexibility of 60 or less, preferably 50 or less. It is desirable to carry out thermocompression bonding using a powdered adhesive, which will be described later. The flexibility, breathability, and strength of such composite sheets are particularly important for applications that come into contact with or are used along the human body, such as diaper covers, back sheets for disposable diapers, base sheets for medical patches, and hospitals. This property is particularly important for medical and sanitary materials such as bed sheets, rain jackets, and hats, as well as for simple clothing. This is because the composite sheet used in these applications has an East Softness of 60 or less, particularly 50 or less, since it does not produce any feel or sound. On the other hand, as long as the maximum pore diameter of the porous sheet is 2 μ or less, even if the pore diameter around the fiber crimping part of the nonwoven or woven fabric becomes slightly elongated and larger during lamination, it will not exceed 8000 mm・r (high water resistance of 20 or more). In this case, the composite sheet maintains its ability to withstand water pressure, which is a suitable property for the above-mentioned applications.

A key feature of the present invention is that the above-described porous sheet and reinforcing material are bonded by thermocompression using a powdered adhesive, and the air permeability and transparency of the porous sheet and reinforcing material are improved. A composite sheet with good adhesion and high strength can be produced without impairing physical properties such as moisture and flexibility.

The adhesive used in the present invention has a melting point lower than the melting point of the porous sheet or reinforcing material, and a particle size larger than the pores of the porous sheet and large enough to not leak through the pores of the reinforcing material. Any known adhesive may be used without any particular restriction depending on the type of porous sheet or reinforcing material, as long as it is a powdered adhesive that can be bonded to the porous sheet or reinforcing material by thermocompression bonding. Examples include ethylene adhesive, vinyl acetate adhesive, ethylene-vinyl acetate adhesive, acrylic adhesive, urethane adhesive, ethylene-acrylic adhesive, vinyl-urethane adhesive, and the like. If the melting point of these adhesives is higher than the melting point of the porous sheet or reinforcing material, the porous sheet or reinforcing material will melt and close the pores before the adhesive melts during pressure bonding, so that the desired porosity can be achieved. Composite sheet cannot be obtained. On the other hand, if an adhesive whose particle size is larger than the pore size of the porous sheet or small enough to leak through the pores of the reinforcing material is used, the adhesive will clog the porous sheet or the reinforcing material. No porous composite sheet is obtained. In addition, the particle size of the adhesive is lO ~
A device of about 100 B is easy to use and can be easily used. The upper limit of particle size varies slightly depending on the type of porous sheet or reinforcing material and the intended use of the resulting composite sheet, but if the particles are too large or the particles are bonded together, the porosity of the resulting composite sheet will decrease. This is undesirable because it causes a decrease in flexibility and variations in strength due to assimilation of the adhesive. I) η
When laminating the low-density polyethylene porous sheet described above with non-woven fabrics or woven fabrics such as nylon or polypropylene,
A vinyl acetate modified polyethylene adhesive powder having a low melting point can be suitably used.

The above-mentioned powder adhesive is generally applied on one side or on a porous sheet or reinforcing material -L, which has been preheated to a temperature above the melting point of the adhesive, using equipment that has the function of uniformly scattering or applying the powder. After being uniformly sprayed or coated on the art dealer, it is heat-pressed. That is, by scattering or applying the powder onto a preheated adherend, the powder particles adhere to the adherend, albeit weakly, so that the powder can be prevented from falling off. At this time, if there is too little ffi: of the powdered adhesive, it will cause uneven adhesion, and if it is too much, the porosity and flexibility of the resulting composite sheet will not only decrease, but also increase the cost of the adhesive. 3-30g/d for quality sheet or reinforcement material,
Especially LZ is preferably 5 to 10 g/d.

The method of thermocompression bonding in the present invention is not particularly limited as long as it can be carried out by bonding the porous sheet and reinforcing material as described above. Generally, a method is adopted for cresting, in which a porous sheet and a reinforcing material coated with an adhesive on one side (adhesive surface) are pressed at a predetermined temperature between rolls to bond them by thermocompression. The temperature and pressure at this time may be adjusted to obtain a composite sheet with desired physical properties. For example, when pasting a linear low-density polyethylene porous sheet and a nylon nonwoven fabric,
Temperature below ℃, roll pressure 100 kg/L! When the winding speed of the sheet is approximately w2 and the sheet winding speed is 5 to 50 m/min, an air permeable and moisture permeable composite sheet that is flexible and has strong adhesive strength can be obtained. In the above description, a composite sheet having a two-layer structure of a porous sheet and a reinforcing material has been described, but in the present invention, a composite sheet having three or more layers is also applicable in principle.

(Effects) As is clear from the above explanation, according to the present invention, the porosity of the porous sheet and the reinforcing material can be improved by a simple method of thermocompression bonding the porous sheet and the reinforcing material via a powder adhesive. Good adhesion can be imparted without impairing flexibility or flexibility. Therefore, the composite sheet obtained by the present invention can be used, for example, as a diaper cover, a diaper back sheet, a medicinal patch base sheet, a bandage, a rain gear, a hat, a wrapping paper, and a shoe inner sheet.

It is used in a wide range of applications, including medical hygiene materials such as hospital sheets, packaging materials, and filter applications.

(Examples) Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not particularly limited to the following implementation system. Also,
The physical properties were measured by the method shown below.

1) Air permeability: Measured according to JIS-P-8117 (Gurley method).

2) Flexibility: When a sample piece cut to a width of 50 mm with a lid is placed on a table, and one end of the piece is gradually protruded from the table, the height of the tip hanging down is 20 mw + the difference between the table and the sample piece. Measure the distance between the ends (in am).

3) Maximum pore diameter; measured according to ASTM-F31B-70 (11).

4) Tensile strength and elongation; Measured according to JrS-P-811; 1 (kg/25 mm, %).

5) Moisture permeability: JIS-Z-0 at 4θ℃ and 90% relative humidity
Measured according to 208 (g/Iken 24)1 r).

6) Water pressure resistance; measured in accordance with JIS-1-1092 (m
mH20).

7) Lamination strength; J I 5-P-811:'1
Measured according to 01m (gr/25mm).

The data measured in the vertical and horizontal directions is the degree of flexibility.

If the strength and elongation are different between the vertical and horizontal directions, the vertical/horizontal
Displayed horizontally as below.

Table 1 also lists the porous sheets and reinforcing materials used in the examples.

The porous sheet is made of high-density polyethylene, as shown in Table 1.
Calcium carbonate and small amounts of stabilizers and processing aids were added to 100 parts by weight of polypropylene and linear low-density polyethylene and mixed, and the resin temperature was adjusted to 250°C for high-density polyethylene, 230°C for polypropylene, and 220°C for linear low-density polyethylene. It was made into pellets using a twin-screw press ratio machine. Then,
Sheets were produced and stretched using a 501φ extruder at resin temperatures of 250°C, 230°C, and 185°C, respectively. The stretching temperatures were 115°C, 130°C, and 80°C, respectively, at approximately 2.0°C in the longitudinal and transverse directions.
Stretched 2X1.9 times, linear low density polyethylene is 1.7
A film stretched by 1.4 times was used.

Nylon nonwoven fabric, nylon woven fabric, and polypropylene nonwoven fabric were used as the reinforcing material sheet, and a polyethylene split fabric with large openings was used as a comparison material.

In addition, as an adhesive, ethylene-vinyl acetate-modified polyethylene powder (manufactured by Asahi Kasei ■, Xante-1, I),
(melting point: approx. 70°C) to confirm that there is adhesion between the porous sheet and the reinforcing material in advance, and to remove fine powder so that it does not leak from the pores of the reinforcing material when sprayed on the reinforcing material. I used the one from

Examples 1-8. And Comparative Examples 1 to 4 As for the bonding method of this example, all pieces of reinforcing material were
Two-layer lamination was performed by spraying powdered adhesive on 01. The reinforcing material was heated in advance using a preheated roll at 80° C., and the powdered adhesive was sprinkled onto it. Next, the reinforcing material sprinkled with this adhesive powder is bonded to a thermocompression roll (the metal roll side is heated. The facing roll is a silicone roll at 70 to 1!0℃).
A porous sheet was placed on the adhesive side, and the reinforcing material side was placed in contact with a metal heating roll for thermocompression bonding. Next, it was passed through a cooling roll and wound up. pressure is 100k
The test was carried out at a speed of 1 g/mark 2 (gauge pressure) and 1 CC11 (1/min).The physical properties T- of the composite sheet thus obtained are summarized in Table 2.

From this example, the air permeability of the porous sheet used.

It has been found that a composite sheet having moisture permeability and flexibility as well as the flexibility and strength of the reinforcing material can be obtained in a container.

In particular, in Examples 3 to 8, when the flexibility of the porous sheet and the reinforcing material was 30 or less and 50 or less, the flexibility of the resulting composite sheet was also [tj7 at 50 or less, and these It can be used as a material for diaper back sheets, patch base sheets, sheets, rain bags, hats, etc. It fits the human body very well, and has excellent strength and moisture permeability.
It turned out to be a luxurious material with high water resistance.

In Comparative Example 1, the size of the holes in the reinforcing material was too large compared to the size of the adhesive particles, so the adhesive leaked from the holes and was attached to the thermocompression roll, making it impossible to bond continuously. Ta.

In addition, in Comparative Example 2, the amount of powder adhesive used was 40 g/I, so the adhesive was crushed during thermocompression bonding, forming a large film in some areas, resulting in a decrease in flexibility, air permeability, and moisture permeability. I didn't like it.

In Comparative Example 3, a porous sheet and a nylon woven fabric were bonded together using a chloroprene latex solvent-based adhesive (GXP-200 manufactured by Konishi ■), but the pores of porous sheet 1 were crushed and the air permeability decreased significantly. However, flexibility also decreased.

In Comparative Example 4, a thermocompression bonded laminate of a linear low-density polyethylene porous sheet and a woven nylon fabric was investigated.
It was found that at 130°C, the porous sheet melted and the pores collapsed, making it impossible to form a composite sheet.

Claims (1)

[Claims] 1) A method for manufacturing a composite sheet, which comprises bonding a porous sheet and a reinforcing material by thermocompression using a powdered adhesive. 2) Porous sheet has a thickness of 10 to 500μ and a maximum pore diameter of 2
Less than μ, moisture permeability 2500-5000g/m^2・24H
r) The method according to claim 1, wherein the air permeability is 50 to 2000 seconds/100cc. 3) The method according to claim 1, wherein the porous sheet is a stretched sheet of a composition comprising 100 parts by weight of a polyolefin resin and 50 to 400 parts by weight of a filler. 4) The method according to claim 3, wherein the polyolefin resin is medium/low pressure polyethylene. 5) The method according to claim 1, in which a reinforcing material having a pore diameter larger than that of the porous sheet is used. 6) The method according to claim 5, wherein the reinforcing material is a nonwoven fabric or a woven fabric. 7) Use of a powdered adhesive having a melting point lower than that of the porous sheet or the reinforcing material, and a particle size larger than the pore diameter of the porous sheet, and having a size that does not leak from the pores of the reinforcing material. The method described in Section 1. 8) Apply powder adhesive to porous sheet or reinforcing material 3 to 3 times.
2. The method according to claim 1, wherein the adhesive is sprayed or applied at a rate of 0 g/m^2 and then thermocompression bonded at a temperature above the melting point of the adhesive and below the melting points of the porous sheet and the reinforcing material.