JPH02162008A - Manufacture of air-permeable composite sheet - Google Patents

Abstract

PURPOSE:To simultaneously perform both the production of porous thermoplastic resin film and its bonding to porous base material such as non-woven fabric or the like by a method wherein composition consisting of the thermoplastic resin, inorganic filler and liquid component, which stands against the heat having the specified temperature, is extrusion-laminated to the porous base material. CONSTITUTION:Both the bonding of composition consisting of thermoplastic resin, inorganic filler and liquid component, which stands against the heat having a temperature of 250 deg.C or higher, to porous base material and the production of porous thermoplastic resin film are simultaneously performed by extrusion-laminating the composition to the porous base material. As the thermoplastic resin, low density polyethylene, high density polyethylene or the like, the melt index of which is preferably 2 - 15 and which is preferably in the form of powder of 20- 200 mesh, is exampled. As the inorganic filler, calcium carbonate, barium sulface or the like, the mean particle diameter of which is preferably 1 - 10mum, is exemplified. As the liquid component, plasticizer or liquid hydrocarbon polymer, which stands against the heat having a temperature of 250 deg.C or higher, is used. As the porous base material, non-woven fabric, woven fabric or the like made of polyester or high density polyethylene, the void of which is preferably 95% or less, is cited. The preferable blending ratio is 20 - 300pts.wt. of the inorganic filler to 100pts.wt. of the thermoplastic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing an air-permeable blended sheet comprising a porous base material and a thermoplastic resin film.

In recent years, porous substrates such as non-woven fabrics and water permeability and moisture permeability.

Breathable composite sheets made of perforated films that have the function of adjusting breathability are becoming widely used. Typical examples include disposable diapers, sanitary products,
Examples include disposable warmers and filters. Methods for producing these breathable composite sheets are broadly classified into two PJ methods.

(1) A method of bonding a porous base material to a thermoplastic resin film that has been made porous in advance by stretching a film blended with inorganic and organic fillers or removing the filler. (2) Heat This is a method in which a plastic resin film and a porous base material are joined together, and then the thermoplastic resin film is made porous by a method such as needle punching or the like.

Both manufacturing methods are divided into two steps: a step of forming pores in the thermoplastic resin film and a bonding step of bonding it to a porous base material. For that reason, quality control.

Not only is it disadvantageous in terms of process control, but also the perforation equipment.

Since two types of bonding devices are required, there is a drawback that the equipment investment is large and it is difficult to reduce the cost of the product.

[Problems to be Solved by the Invention] An object of the present invention is to provide a method for simultaneously making a thermoplastic resin film porous and bonding it to a porous substrate such as a nonwoven fabric, which has not been achieved by conventional methods. It is.

[Means for Solving the Problems] In view of the above-mentioned current situation, the present inventors have made extensive studies and have developed a composition consisting of a thermoplastic resin, an inorganic filler, and a liquid component having heat resistance of 250°C or higher. It was discovered that by extrusion laminating a thermoplastic resin film onto a porous substrate, the thermoplastic resin film becomes porous at the same time as bonding, and the present invention was completed.

The present invention will be explained in detail below.

Examples of the thermoplastic resin include polyolefin resins such as low density polyethylene, high density polyethylene, polypropylene, ethylene-vinyl acetate copolymer, and/or blends thereof. Melt index (Ml
) 2 to 15 are suitable, and the shape is 20 to 20
A powder form with 0 mesh is preferred.

Inorganic fillers include calcium carbonate, barium sulfate,
Talc, clay, magnesium carbonate, barium carbonate, kaolin, silica, diatomaceous earth, magnesium sulfate, calcium sulfate, zinc oxide, magnesium hydroxide, aluminum hydroxide, mica, asbestos powder, glass powder, shirasu balloon, zeolite, silicate clay, etc. can be mentioned.

These can be used alone or in combination.

The average particle size of the inorganic filler is preferably 1 μ to 10 μ, more preferably 1 μ to 5 μ. Particle size is 1
When the particle size exceeds 0μ, the density of pores and extrusion lamination processability deteriorate, and when the particle size is less than 1 part, it may be difficult to form pores. Further, it is preferable that the inorganic filler is treated with a fatty acid or a metal salt thereof from the viewpoint of laminating processability and dispersibility.

As the liquid component to be mixed with the thermoplastic resin and inorganic filler, one or more plasticizers or liquid hydrocarbon polymers having heat resistance of 250° C. or higher may be used. During extrusion lamination, if the heat resistance of the liquid component is poor, it will foam and become impossible to form a film.

Therefore, it is important that the liquid component has good heat resistance, that is, the loss on heating is small. Measured with a thermobalance (temperature increase: 5℃)
/min, in air) heating loss is 5% at 250° C., more preferably 326 or less. As such components, epoxidized soybean powder and liquid polybutene are most suitable.

Porous substrates include nonwoven fabrics, woven fabrics, and mixed nonwoven fabrics made of synthetic fibers and natural fibers such as polyester, high-density polyethylene, propylene-ethylene copolymers, rayon, and nylon, and papers with rough surfaces such as thin paper. Further examples include inorganic nonwoven fabric base materials such as glass fiber and rock wool. These porous substrates preferably have a porosity of 95% or less, more preferably 90% or less. This is because, in extrusion lamination, the porosity of the porous base material temporarily decreases due to pressure bonding, but after the pressure bonding, the porosity returns to close to that of the porosity of the porous base material. At that time, the porosity is 95%
This is because the bonding point between the thermoplastic resin film and the porous base material is likely to peel off and tear if it exceeds this range.

The blending ratio of thermoplastic resin, inorganic filler, and liquid component is 20 parts by weight of inorganic filler per 100 parts by weight of thermoplastic resin.
-300 parts are preferable, and 100-200 parts are more preferable. If the amount of inorganic filler is less than 20 parts, the perforation point will be extremely small, and if it exceeds 300 parts, crosstalk dispersion and drawdown properties of extrusion laminate will be poor, making it impossible to obtain a satisfactory breathable composite sheet. There is. The blending ratio of the liquid component is 2 to 5 parts by weight per 100 parts by weight of the thermoplastic resin.
It is 0 copies. If the amount is less than 2 parts, it becomes difficult to form pores, and if it exceeds 50 parts, the moldability of the extrusion laminate will deteriorate, and in extreme cases, problems such as surging may occur.

For mixing, a mixer such as a Henschel mixer or a dumbler type mixer is appropriately selected. As for the mixing order, for example, a liquid component is added to a thermoplastic resin powder and thoroughly mixed, and depending on the type, an inorganic filler that has been predried and water removed is then added and mixed again to obtain a blend. These blends are mixed and granulated using a conventional single-screw extruder, twin-screw extruder, mixing roll, Banbury mixer, or other equipment.

Extrusion lamination may be carried out using a conventional extrusion and lamination device. That is, the porous base material is used as a raw material, and if necessary, it is pretreated such as corona discharge treatment and ozone treatment, and then mixed.
The kneaded and granulated mixture is extruded and laminated. The resin temperature is set to an appropriate temperature depending on the thermoplastic resin used. For example, in the case of polyolefin resin, the temperature is 250 to
350°C is common. However, it is preferable to keep the temperature as low as possible without impairing the adhesive properties with the porous base material, since this increases the number of pore-forming points. Laminate thickness is 1
0μ to 50μ is preferable, more preferably 15 to 30μ
μ. If it is less than 10μ, the processability is poor, such as breakage of the melted thermoplastic resin film, and if it exceeds 50μ, the number of perforation points may be extremely reduced.

In extrusion lamination, pressing and cooling are performed almost simultaneously. During the cooling process, shrinkage force is generated in the thermoplastic resin film, creating voids at the interface between the inorganic filler and the thermoplastic resin, and the thermoplastic film becomes porous. However, porosity does not occur in a single film formed as a cast film.

Further, even when a mixture of only a thermoplastic resin and an inorganic filler is extruded and laminated onto a porous substrate such as a nonwoven fabric, no porosity occurs.

[Example] Example 1 Melt index (Ml)8. Density is 0.917 g
41 kg of epoxidized soybean oil (trade name: rD-130P, manufactured by Adeka Argus Chemical Co., Ltd.) was added to 4 kg of powder of low-density polyethylene resin (manufactured by Tosoh Corporation [Petrosen 4203]) with a particle size of 1.5 cm, mixed with a Henschel mixer, and then averaged. Calcium carbonate with a particle size of 2.2μ (“Snowlight 5SJ” manufactured by Maruo Calcium Co., Ltd.) was added to the
g and thoroughly mixed the composition using a 50 mmφ vented screw extruder (Tanabe Plastic Machinery Co., Ltd.).

The mixture was kneaded and granulated using a model US50. Next, a laminator (Model TP-3 manufactured by Braco Co., Ltd.) with a 25 mm diameter extruder was used.
50), the material is polyester, and the weight is 40 g.
/rd, a nonwoven fabric with a porosity of 75% (manufactured by Unitika Co., Ltd., TO403WDO) was used as the raw fabric and extrusion laminated.

The main processing conditions are resin temperature 300℃, take-up temperature 60m
/ r n i n , and the laminate thickness is 20 μm.

The moisture permeability (JIs,
20208. temperature 40℃, humidity 90%), water resistance (
Table 1 shows the results of the measurements (J15L-1069A method).

Example 2 The third component was liquid polybutene (Japan Petrochemical Co., Ltd., H
A sheet was obtained in the same manner as in Example 1 except for using V300). Table 1 shows the results of measuring the moisture permeability and water resistance of this sheet.

Comparative Example 1 A composition obtained under the same conditions as Example 1 was mixed and granulated using a 50 wφ vented screw extruder (Tanabe Plastics Co., Ltd., model VS50), and then granulated at 25 o+m
Using a laminator (manufactured by Plako Co., Ltd., model TP-350) equipped with a φ extruder, it was molded as a KIST film without being composited with a porous substrate.

The main conditions are resin temperature 300℃, take-up speed 60m/
min, laminate thickness is 20μ. Table 1 shows the results of moisture permeability and water resistance measured for this film.

Comparative Example 2 Using a laminator (manufactured by Placo Co., Ltd., model TP-350) with a 25 mmφ extruder, a nonwoven fabric (manufactured by Unitika Co., Ltd., TO403DO) made of polyester, having a tsubo Q of 40 g/d, and a porosity of 75% was used as a raw material. To 4 kg of powder of low-density polyethylene resin (trade name "Betrocene" -03 manufactured by Tosoh Corporation) having a melt index (Ml) of 8 and a density of 0.917 g/m'', an average particle size of 2.2 was added.
6 kg of μ calcium carbonate (“Snowlight 5SJ” manufactured by Maruo Calcium Co., Ltd.) was added and thoroughly mixed.
The mixture was kneaded, granulated, and extrusion laminated using Ichibe Plastic Co., Ltd. (model VS50). The main processing conditions are resin temperature 30
0°C, take-up speed 60 m/min.

Laminate thickness: 20μ The results of moisture permeability and water resistance measured for this film are shown in Table 1.

[Effects of the Invention] According to the present invention, it has become possible to bond a porous base material and a thermoplastic resin film and to form pores at the same time. As a result, it has become possible to increase the production speed of breathable composite sheets with excellent moisture permeability and water resistance, and quality control and process control have become easier.

Furthermore, it has superior heat resistance and solvent resistance compared to conventional methods of applying eyebrows using solvent-based adhesives or hot-melt eyelids, and its industrial value is high.

Claims (1)

[Claims] (1) A method for producing a breathable composite sheet, which comprises extrusion laminating a composition comprising a thermoplastic resin, an inorganic filler, and a liquid component having heat resistance of 250° C. or higher onto a porous base material.