JPH09123329A - Manufacture of porous superposed sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make adhesion between porous base materials excellent, make them hardly peel, and reduce irregularity in breathability by adhesively superposing the porous base materials through powdered hot melt resin layer. SOLUTION: A porous superposed sheet is formed of an adhesive layer which contains porous base materials 1, 3 and a powdered hot melt resin layer 2. For the porous base material 1, a porous film of polyolefin or fluororesin is used. The porous base material 1 is adhesively superposed on the porous base material 3 of reinforcing cloth or nonwoven fabric consisting, for example, of organic or inorganic fibers. For superposing adhesion of the porous base materials 1 and 3, one or more kinds of hot melt resin of powdered polyolefin, polyester, acrylic, styrene or polyamide resin are used. For the superposing adhesion of the porous base material, for example, a continuous method wherein a layer of powdered hot melt resin is provided on a continuous porous base material and other continuous porous base material is arranged thereon in sequence so as to attach with heat and pressure is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a porous superposed sheet which is capable of superposing and adhering a porous base material with good maintainability of its porosity and excellent in controllability of porous characteristics.

[0002]

BACKGROUND OF THE INVENTION Breathable materials made of a superposed body of porous substrates are used in various fields, for example, as a bag for storing a disposable body warmer or a waterproof breathable sheet on a wall surface. Such a breathable material is adjusted to a sheet having various properties such as a breathable waterproof type, a breathable water type, or a reinforced type by changing the combination of the porous base materials to be superimposed depending on the use.

Regarding the above-mentioned superimposing type breathable material, the group to which the present inventor belongs has previously proposed a method of superposing and adhering a porous substrate and a polyolefin-based porous film via a hot-melt type porous adhesive film. (Japanese Patent Laid-Open No. 63-
No. 60744). This porous superposed sheet is a ventilating and water permeable type that allows gas and liquid to pass therethrough, and is a reinforced type that uses a reinforcing porous base material. Therefore, it is possible to obtain the porous superposed sheet having the desired performance even if the porous adhesive film is used for adhesion.

However, in the above method, the porous adhesive film is melted when the porous base material is thermocompression-bonded and superposed and adhered, and the porous adhesive film is formed of a stretched film. The shape of the porous base material tends to change and the pores tend to be blocked. Therefore, it is difficult to control the air permeability or prevent the variation of the air permeability, and it is difficult to control the porous characteristics.

[0005]

DISCLOSURE OF THE INVENTION The present invention has excellent adhesiveness between porous base materials and is difficult to peel off, and is capable of superposing and adhering a porous base material with good maintainability of its porosity and excellent controllability of porous properties,
An object of the present invention is to develop a manufacturing method capable of obtaining a porous superposed sheet having little variation in air permeability.

[0006]

The present invention provides a method for producing a porous superposed sheet, which comprises thermocompression-bonding a porous base material through a powdery hot-melt resin layer to superpose and adhere it. .

[0007]

EFFECTS OF THE INVENTION According to the present invention, the fineness and even distribution are excellent through the powdery hot-melt resin layer, the air permeability and the adhesive strength are small, and the averageness thereof is excellent, and the porosity is high. Adhesive layer according to the porous characteristics of the base material can be easily formed with good controllability, and the porous base material performance such as air permeability of the porous base material is enhanced by thermocompression bonding through the adhesive layer. To obtain a porous superposed sheet that can be superposed and adhered while maintaining it, has excellent adhesive strength and is hard to peel off, has little variation in breathability, and has excellent adhesiveness and evenness of breathability, and excellent balance between breathability and adhesiveness. You can

In the above, a spraying method by spraying an adhesive solution instead of powder may be considered. In that case, the adhesive solution permeates into the pores of the porous substrate due to the bleeding or flow of the solution at the time of spraying. Adhesive strength is difficult to develop, and pores are blocked to cause variations in breathability. Further, a drying step of the adhesive is also required, which lowers the production efficiency.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The production method of the present invention is to obtain a porous superposed sheet by thermocompression-bonding a porous base material through a powdery hot-melt resin layer to superpose and adhere.
Examples of porous superposed sheets according to the present invention are shown in FIGS. 1, 2 and 4.
It was shown to. Reference numerals 1 and 3 are porous substrates, and 2 is an adhesive layer composed of a powdery hot-melt resin layer. In the illustrated example, 1 of the porous base material is a porous film, and 3 is a porous base material for reinforcement.

As the porous base material, an appropriate material is used depending on the type of porous and waterproof sheet such as a breathable waterproof type, a breathable water type, a reinforced type and the like, and a porous superimposing sheet for forming porous properties such as breathability. It is possible to use any porous substrate according to the conventional porous superposed sheet. Therefore, the porous substrate is
Depending on the porous superimposed sheet for forming purpose, for example, a combination of porous films, a combination of a porous film and a porous substrate for reinforcement, and the like can be used in an appropriate combination of the same kind or different kinds, As illustrated in FIG. 1 and FIG. 2, an arbitrary number of porous base materials of two layers or three layers or more can be superposed and adhered to form the porous superposed sheet of the present invention.

By the way, in the above, in order to form a breathable and waterproof type, that is, a type of a porous superposed sheet of a type that allows gas to permeate but does not allow liquid to permeate, for example, a porous substrate made of a porous film having fine pores of micron order or less Materials can be preferably used. Such a porous film is, for example, a method in which a polyolefin-based or fluororesin-based film such as polyethylene or polypropylene is stretched, or a film in which an elution component is dispersedly contained is stretched if necessary, and then the elution component is contained in the film. It can be obtained by an appropriate method such as a method of further removing.

The porous film that can be preferably used when forming the breathable waterproof type porous superposed sheet is 1
cc / cm ² / sec or more, especially 5cc / cm ² / sec or more, especially 10cc
It shows an air permeability of / cm ² / sec or more, and does not cause water leakage at a water pressure of 100 mm for 30 minutes or more, especially for 45 minutes or more, especially for 60 minutes or more. Is especially preferred.

In the above, since the thickness of the porous film is usually as thin as 300 μm or less, especially 10 to 200 μm and its strength is poor, it is often superposed and adhered to the reinforcing porous substrate. By the way, examples of the reinforcing porous base material include paper, cloth or nonwoven fabric made of organic or / and inorganic fibers such as polyamide fiber, polyester fiber, glass fiber and metal fiber, and porous plastic such as punching film wallif. Examples include sheets, foam sheets and perforated sheets.

The perforated sheet can be obtained by an appropriate method such as a method in which a plastic sheet having a necessary reinforcing effect is perforated through needles, heat or the like, and allows liquid to pass therethrough. You may Therefore, a ventilation-permeable porous superposed sheet can be obtained by using an appropriate combination of reinforcing porous base materials that also permeate liquid. A liquid-permeable porous film can be obtained by stretching the film mixed with a filler such as calcium carbonate.

If necessary, agents such as fungicides, antibacterial agents, deodorants, insect repellents and pesticides may be added to the porous base material to impart the required functions. The thickness of the porous substrate can be appropriately determined according to the intended porous superposed sheet and the like, but is generally 10 mm or less, preferably 5 mm or less, and particularly 1 μm to 1 mm.

In the present invention, a powdery hot-melt resin is used for superposing and adhering the porous substrate. The hot melt resin is not particularly limited, and an appropriate one may be used depending on the type of the porous base material to be adhered, the porous superimposed sheet for the purpose of formation, and the like. Hot-melt resin that can be preferably used from the viewpoint of maintaining the pore structure of the porous substrate is melted at a lower temperature than the porous substrate to be bonded,
In particular, it melts at a temperature of 3 ° C. or higher, particularly 5 ° C. or higher.

By the way, as a general hot-melt resin, for example, polyethylene, particularly ultra-low-density polyethylene, polypropylene, polyolefin resin such as ethylene / vinyl acetate copolymer, ethylene / acrylic ester copolymer, acrylic resin, etc. Acrylic resins, SIS and S containing alkyl ester such as acid and methacrylic acid
Examples thereof include styrene resins such as BS, SEBS and SIPS, polyester resins, polyamide resins, urethane resins and hot melt silicone resins. The hot melt resins can be used alone or in a blend of two or more.

The superposed adhesion of the porous base material can be carried out by thermocompression bonding through a powdery hot melt resin layer. Appropriate methods such as a hot roll method and a hot press method can be applied to the thermocompression bonding.

The formation of the powdery hot melt resin layer is
It can be performed by an appropriate method. Examples thereof include a method in which an appropriate amount of powdered hot-melt resin is sprayed on a porous substrate through a perforated material such as a sieve or a mesh, a method in which it is sprayed by air transportation, or a material such as a nonwoven fabric in advance. It may be prepared by a kneading method, a spraying method, or the like, or a method in which a solution is mixed, coated and dried.

Therefore, in the present invention, a layer of powdered hot-melt resin is provided on a long porous substrate, and another long porous substrate is sequentially arranged on the layer to heat the layer. A continuous method of pressure bonding, a single-piece method in which such layers are attached and thermocompression-bonded for each short sheet, or, as illustrated in FIG. 3, a porous material in which a powdery hot-melt resin layer 2 is held on one side or both sides. The substrate 1 can be formed in advance, and the porous substrate can be formed by superposing and adhering the porous substrate on another porous substrate by an appropriate method such as thermocompression bonding. The holding treatment of the hot-melt resin layer on the porous substrate can be carried out by an appropriate method such as fusion treatment by heating,
The holding of the layer on both sides of the porous substrate can be performed by holding treatment on each side. As illustrated in FIG. 4, the holding layer of the layer may be provided on one side or both sides of the porous superposed sheet.

The size of the powdery hot-melt resin provided on the porous substrate is appropriately determined by the pore size of the porous substrate. From the point of preventing the powdery hot-melt resin from being buried in the pores of the porous base material and blocking the pores, a particle diameter larger than the pore diameter, especially 1.1 times or more,
In particular, it is preferable to use a hot-melt resin powder having a particle diameter of 2 times or more. The typical particle size of the hot melt resin used is 5 mm or less, especially 0.1 to 1000 μm,
Particularly, it is 1 to 500 μm.

The area where the powdery hot-melt resin layer is provided, that is, the overlapping adhesion area of the porous substrate through the powdery hot-melt resin layer, is assumed to be a flat surface in terms of adhesive strength and air permeability. 90% or less based on the area, preferably 1 to 80%, particularly 5 to 60%.

The porous superposed sheet according to the present invention may be provided with one or both of the pressure-sensitive adhesive layer 4 and the breathable coat 5 of the release agent on one side or both sides thereof, as illustrated in FIGS. When a coat of a release agent is provided, the porous superposed sheet can be used as a wound body which is adhered to its own back surface via the adhesive layer, and a separate separator for protecting the adhesive layer until it is put into practical use. Has the advantage that it can be omitted.

The coating of the release agent can be formed by providing a coating film of the release agent on the surface of the porous base material or the porous overlay sheet before the overlay adhesion. As the release agent, for example, a silicone-based agent, a long-chain alkyl-based agent, a fluorine-based agent, or the like can be used. Above all, silicone-based ones that can be cured by radiation such as electron beams and ultraviolet rays are preferable. The formation of the breathable coat of the release agent is generally performed by a coating method.For example, after applying the release agent to a predetermined surface of the porous substrate, the release agent that has penetrated into the holes is blown off by blowing air and then heat treated. It is possible to employ a method of forming a coating film by coating, a method of spraying a release agent, and the like, and an appropriate method may be used.

The pressure-sensitive adhesive layer is provided on the entire surface or a part of the porous superimposing sheet so that the porous superimposing sheet can be easily adhered and fixed to an adherend and the like so that ventilation can be performed through the porous superimposing sheet. . Therefore, the pressure-sensitive adhesive layer is formed by partially coating a proper shape such as stripes or dots as shown in FIG. 5 or by depositing a fibrous pressure-sensitive adhesive substance as shown in FIG. 6 on a non-woven fabric. It is formed in a porous state. The adhesive layer in a porous state can be applied to both partial coating and entire surface coating. The adhesive layer in a porous state which is preferable from the viewpoint of the balance between adhesive strength and air permeability, has an average fiber diameter of the fibers forming the adhesive layer of 0.5 to 100 μm, especially 1 to 50 μm, and a fiber having such an average fiber diameter. Is 1 to 50 g / m ² , especially 1 to 30
g / m ^2, in particular those deposited in a nonwoven fabric or tangled fibrous at a rate of 2 to 20 g / m ^2.

To attach the adhesive layer in a porous state to the porous superposed sheet, for example, the adhesive substance is applied by an appropriate method such as a melt blow method or a curtain spray method in which the adhesive material is spread while being heated and melted by hot air. A method of forming a porous adhesive layer by fibrating it, expanding and depositing it on a separator, and transferring it to a predetermined location of the porous superposition sheet, or a fibrous adhesive property at a predetermined location of the porous superposition sheet. It can be performed by an appropriate method such as a method of directly developing and depositing the substance. The fiber-deposited pressure-sensitive adhesive layer has advantages such as excellent fineness and even distribution of pores and little deviation in air permeability and adhesive force.

To form the adhesive layer, for example, butyl type or SB type is used.
Appropriate adhesive substances such as rubber-based adhesives such as R-based, NR-based, NBR-based, and their blend-based adhesives, acrylic adhesives, silicone-based adhesives, and the like can be used. For forming the adhesive layer in a porous state, for example, an adhesive substance which exhibits adhesiveness at room temperature and can be heated and melted, such as a hot-melt adhesive, is preferably used. Examples thereof include the polyolefin-based resins, styrene-based resins, acrylic resins, urethane-based resins, and other elastomer-type resins, and silicone-based hot-melt-type pressure-sensitive adhesives, which are exemplified above as the hot-melt-type resin.

The adhesive substance may be used alone or in combination of two or more. By the way, tack and strength can be adjusted by adding olefin resin to styrene resin. When preparing the adhesive substance, an appropriate additive such as a tackifier, a softening agent, or an anti-aging agent may be added, if necessary, as in the case of the hot melt resin.

The thickness of the adhesive layer can be appropriately determined depending on the purpose of use of the porous superposed sheet and the like. By the way, when the surface roughness of the adherend such as wall surface is large, it may be 10 mm or more, but generally 7 mm or less, especially 5 μm to 5 m.
The thickness is m, especially 0.1 to 3 mm. The adhesive layer is
It may be formed as a superposition of different kinds of adhesive substances.

The porous superposed sheet of the present invention can be used for various purposes such as forming a bag for containing a heat-generating composition in a disposable body warmer, forming a wall sheet for preventing dew condensation, etc., depending on the purpose of use. For example, it can be obtained with various properties such as a ventilation waterproof type, a ventilation water passing type, or a reinforcing type.

[0031]

【Example】

Example 1 A film made of 100 parts of linear low-density polyethylene (parts by weight, the same applies hereinafter) blended with 120 parts of calcium carbonate was uniaxially stretched 4 times to obtain an average pore diameter of 0.5 μm and a transparency. Humidity 600 g / m ² · day, R (range of variation; maximum value-minimum value): 50 (575 to 625), ethylene having a particle size of 0.5 to 20 μm on a polyethylene porous film having a thickness of 60 μm -Vinyl acetate copolymer powder is sprinkled through a sieve, and the basis weight is 50 g on the scatter layer.
A porous non-woven fabric sheet was obtained by arranging a polyamide-based non-woven fabric of / m < ² > and thermocompressing it at 80 to 90 [deg.] C. through a heat roll to perform superposition adhesion.

Example 2 Instead of the ethylene / vinyl acetate copolymer, a particle size of 100-
A porous superposed sheet was obtained in the same manner as in Example 1 except that a polyamide hot melt resin powder of 500 μm was used and a polypropylene nonwoven fabric having a basis weight of 20 g / m ² was used instead of the polyamide nonwoven fabric.

Comparative Example 1 100 parts of linear low-density polyethylene and 1 part of calcium carbonate
A laminate film obtained by co-extruding 20 parts of the mixture and 100 parts of ethylene / vinyl acetate copolymer of 120 parts of calcium carbonate was uniaxially stretched 4 times, and the average pore diameter was 0.5 μm. , Moisture permeability 560g / m ² · d
ay, R: 50, 60 μm thick laminated porous film (polyethylene layer thickness 40 μm) is formed, and a polyamide having a basis weight of 50 g / m ² is formed on the ethylene / vinyl acetate copolymer layer having a thickness of 20 μm. The porous non-woven fabric was obtained by arranging the non-woven fabric and thermocompressing the non-woven fabric at 80 to 90 [deg.] C. through a hot roll to perform superposition adhesion.

Comparative Example 2 A porous superposed sheet was obtained in the same manner as in Comparative Example 1 except that a polypropylene-based nonwoven fabric having a basis weight of 20 g / m ² was used instead of the polyamide-based nonwoven fabric.

Evaluation Tests Regarding the porous superposed sheets obtained in Examples and Comparative Examples, the water vapor transmission rate and its change rate (water vapor transmission after superposition adhesion / water vapor transmission before superposition adhesion × 100), and R (variation in air permeability). Range),
Also, R / water vapor permeability was examined. The results are shown in the following table.

[0036]

From the table, it can be seen from the table that the rate of change in moisture permeability is small and the performance of the porous material in the porous substrate is excellent, and there is little variation in breathability, and the breathability is uniform over the entire superposed sheet. It can be seen that it has excellent properties.

[Brief description of the drawings]

FIG. 1 is a sectional view of an example of a porous superposed sheet.

FIG. 2 is a sectional view of another example of a porous superposed sheet.

FIG. 3 is a sectional view of an example of a porous substrate.

FIG. 4 is a cross-sectional view of still another example of a porous superposed sheet.

FIG. 5 is a cross-sectional view of still another example of a porous superposed sheet.

FIG. 6 is a cross-sectional view of still another example of a porous superposed sheet.

[Explanation of symbols]

 1, 3: Porous substrate 2: Powdery hot-melt resin layer or its adhesive layer 4: Adhesive layer 5: Breathable coat of release agent

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B32B 27/32 B32B 27/32 Z

Claims (4)

[Claims] 1. A method for producing a porous superposed sheet, which comprises thermocompression-bonding a porous base material via a powdery hot-melt resin layer to superpose and adhere it. 2. The porous substrate according to claim 1, wherein a polyolefin-based or fluororesin-based porous film and a reinforcing porous substrate are used, and the hot-melt resin is polyolefin-based, polyester-based, acrylic-based, A method using one or more styrene-based or polyamide-based resins. 3. A powdery hot-melt resin layer is held on one side or both sides of the porous superposed sheet produced by the method according to claim 1 or 2, or a breathable coat of an adhesive layer and a release agent. A porous overlapping sheet having one or both of the above. 4. A porous substrate having a powdery hot melt resin layer held on one side or both sides.