JPH11323001A - Modified porous material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a modified porous material having a polymerized layer of monomers even at the inside of a porous material and a method for producing the modified porous material. SOLUTION: This modified porous material has a polymerized layer of monomers at the outside of the surface and the inside of the porous material. A polymerized amount of the monomers per a unit volume in the vicinity of the outside of the surface of the modified porous material is the same as or less than that of monomers at the inside of the modified porous material per a unit volume. The method for producing the modified material is performed by treating the electrodes carrying dielectric materials by generating discharge in an inside gap of the porous materials by applying an alternative voltage between electrodes carrying dielectric materials 2a and 2b in a state of nipping the porous material by the dielectric materials 2a and 2b in a discharge treatment device arranged so that the dielectric materials are opposed to each other, then bringing the treated porous material 5 into contact with the radical- polymerizable monomers to form a polymerized layer of the monomers at the outside and inside of the surface of the porous material 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a modified porous body and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, as a method of modifying a porous body,
For example, a method in which a porous body is treated by a reduced pressure glow discharge and then brought into contact with a radically polymerizable monomer (for example, JP-A-52-98063, JP-A-52-98)
064), a method in which a porous body is treated with low-temperature plasma by radio waves and then contacted with a vinyl monomer (for example, Japanese Patent Application Laid-Open No. 8-7870, etc.) A method of contacting with a polymerizable monomer (for example,
No. 9-152913) is known. However, in any of these methods, a monomer was polymerized mainly on the outer surface of the porous body, and the monomer was hardly polymerized inside the porous body, and only a modified porous body could be obtained.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a modified porous body having a polymerized layer of a monomer even inside the porous body. An object of the present invention is to provide a method for producing a porous body.

[0004]

The modified porous material according to the present invention is a modified porous material having a polymerized layer of a monomer on the outer surface and inside of the porous material. Amount of polymerization of monomer near surface (per unit volume)
Is equal to or less than the polymerization amount (per unit volume) of the monomer inside the modified porous body. in this way,
It has a polymerized layer of monomer on the outer surface and inside of the porous body, and unlike the conventional modified porous body, the monomer is polymerized uniformly throughout the porous body, or more monomer inside the porous body It is a polymerized modified porous body.

[0005] The method for producing a porous body according to the present invention is a method for manufacturing a porous body, in which the electrode supporting the dielectric body is sandwiched between the dielectric bodies of a discharge treatment apparatus in which the dielectric bodies are opposed to each other. An AC voltage is applied between the electrodes supporting the body, a discharge is generated in the internal voids of the porous body, and the porous body is treated with a radical polymerizable monomer. This is a method in which a polymerized layer of a monomer is formed on the outer surface and inside of the body, and the modified porous body as described above can be easily produced.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The porous body which is the basis of the modified porous body of the present invention, that is, the porous body before reforming has voids in which discharge can be generated as described later. Any material may be used, for example, a fiber sheet (for example, a woven fabric, a knitted fabric, a nonwoven fabric, a composite thereof), a porous film (for example, a perforated film, a film having an uneven structure, etc.), or a foam. it can. The porous body may be made of an inorganic material or an organic material.

[0007] As the porous body, the porosity is higher than 0%,
Less than 99% can be used, and especially less than 95% can be used. Further, the porous body having an average pore diameter of 1 mm or less can be used, and even if it has a mean pore diameter of 0.1 mm or less, particularly 30 μm or less.
On the other hand, the lower limit of the average pore size is a size capable of generating a discharge inside. The average pore diameter can be measured by, for example, a Coulter porometer II (manufactured by Coulter Inc.). In addition, even if it is a porous body which becomes the said average pore diameter by compressing, it can be used.
The thickness of the porous body is not particularly limited.
mm or more and 10 mm or less, preferably 0.1 m
More preferably, it is not less than m and not more than 1 mm. The porous body can be used as long as it becomes within the above-mentioned thickness range by compression. Furthermore, air permeability is 0.5-20
A porous body of 0 ml / cm ² · second, especially 1-150 ml / cm ² · second can be used.

[0008] In particular, the porosity is 95% or less, the average pore size is 0.1
mm or less, thickness 0.1 to 10 mm, air permeability 0.5 to
A porous body that satisfies at least one of 200 ml / cm ² · seconds has been difficult to reform into its interior by conventional discharge treatment (especially when all are satisfied).
In the present invention, even such a porous body can be suitably used.

[0009] The modified porous body of the present invention has a polymerized layer of a monomer on the outer surface and inside of the above-described porous body. The “outer surface” refers to the surface of the porous body that can be in contact with a plane, and the “inside” refers to a portion other than the outer surface. , Fibers) are present. Therefore, the polymerized layer of the monomer is formed on the surface of the porous body constituting the outer surface of the porous body and on the surface of the porous body constituting the inside.

[0010] The monomers constituting the polymerized layer of this monomer are those suitable for the purpose, and moreover, are monomers capable of radical polymerization. For example, styrene compounds (eg, styrene, sodium parastyrene sulfonate), maleic acid compounds (eg, maleic anhydride, dimethyl maleate, etc.), itaconic acid compounds (eg, itaconic acid,
Dimethyl itaconate, acrylamide compounds (eg, acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, etc.), acrylic acid compounds (eg, acrylic acid, methyl acrylate, etc.), methacrylic acid compounds (eg, methacrylic acid, methacrylic acid) Acid, methyl 2-hydroxyethyl methacrylate), allyl compound (eg, diallylamine, allyl alcohol, etc.), vinyl compound (eg, 2-vinylpyridine,
(N-vinyl-2-pyrrolidone, vinyl acetate, etc.) alone or in combination.

[0011] In the modified porous body of the present invention, the polymerization amount of the monomer in the vicinity of the outer surface (per unit volume) is equal to or less than the polymerization amount of the monomer in the inside (per unit volume). The term "near the outer surface" refers to the outer surface and a part of the inner part continuous with the outer surface.

Next, a method for producing the modified porous body of the present invention will be described.

[0013] First, a porous body is sandwiched between electrodes of a discharge processing apparatus in which electrodes carrying a dielectric are arranged so that the dielectrics face each other. By sandwiching the porous body with the dielectric in this way, it is possible to generate a discharge inside the porous body. In addition, since the discharge processing device in which the electrodes carrying the dielectric are arranged so that the dielectrics face each other is used, the discharge can be stably performed without generating spark discharge or the like.

FIG. 1 to FIG. 6 are schematic cross-sectional views of a discharge processing apparatus that can be used in the present invention.

[0015] The discharge processing apparatus shown in FIG. 1 includes a flat electrode 1a carrying a dielectric 2a and a flat electrode 1b carrying a dielectric 2b.
Are disposed so as to face each other.
The porous body 5 is sandwiched between a and b. Since the dielectrics 2a and 2b carried on the flat electrodes 1a and 1b are larger than the surfaces on the opposite sides of the flat electrodes 1a and 1b, it is possible to prevent spark discharge easily occurring between the flat electrodes 1a and 1b. it can. In addition, these flat electrodes 1a, 1b
One flat electrode 1 so that an AC voltage can be applied between them.
a is connected to the AC power supply 4, and the other flat electrode 1b is grounded. Note that, contrary to FIG. 1, one flat electrode 1a may be grounded, and the other flat electrode 1b may be connected to an AC power supply.

The material constituting the flat electrodes 1a and 1b is not particularly limited, but has a specific resistance of 10 ³
Omega · cm or less (preferably less 10 ⁰ Ω · cm) can be used a conductor of, for example, a metal (e.g., stainless steel, aluminum, tungsten, etc.), conductive metal oxides, carbon, or metal powder Ya Conductive rubber obtained by combining a conductor such as carbon powder with rubber can be used.

If the opposing surfaces of the flat electrodes 1a and 1b are curved from the periphery to the side walls, discharge occurs between the side walls of the flat electrodes 1a and 1b and the dielectrics 2a and 2b. Is less likely to occur, and damage to the dielectric can be suppressed, which is preferable.

[0018] Further, in such a discharge treatment apparatus, since the discharge treatment is performed only on the portion sandwiched between the electrodes, the discharge treatment can be performed only on a desired portion. For example, if a grid-like electrode is used as one of the electrodes, the discharge treatment can be performed in a grid corresponding to the shape of the electrode.

The dielectrics 2a and 2b in FIG. 1 cover the entire opposing surfaces of the respective plate-like electrodes 1a and 1b so that a discharge process can be stably performed without generating a spark discharge or the like. In addition, each of the flat electrodes 1a, 1b is set so that no spark discharge occurs between the two flat electrodes 1a, 1b.
1b, the plate-like electrodes 1a, 1b
Protrudes from the surface on the opposite side.

The dielectrics 2a and 2b are preferably non-porous as a whole, but may partially include a porous portion. In particular, when a dielectric including a porous portion is used on the surface on the opposite side, a discharge is generated also in the porous portion of the dielectric, so that the outer surface of the porous body 5 can be subjected to the discharge treatment. If the porous portion is continuous in the thickness direction of the dielectric, spark discharge may occur in the porous portion. Therefore, it is preferable that the porous portion is not continuous in the thickness direction.

As a material constituting the dielectrics 2a and 2b,
For example, glass, ceramic (for example, alumina), rubber (for example, synthetic rubber such as silicone rubber, chloroprene rubber, butadiene rubber, natural rubber, etc.),
Alternatively, a thermoplastic resin (for example, polytetrafluoroethylene, polyester, or the like) can be used. Among these, it is preferable to use a rubber or a thermoplastic resin having excellent elasticity and excellent adhesion to the porous body 5. The thickness of the dielectric is not particularly limited,
It is preferably about 0.05 mm to 5 mm. If the thickness of the dielectric is less than 0.05 mm, the mechanical strength is reduced, and dielectric breakdown is likely to occur. If the thickness exceeds 5 mm, a high voltage is required for discharging.

The discharge processing apparatus shown in FIG. 2 has five small cylindrical electrodes 1a and 1 as electrodes carrying dielectrics 2a and 2b.
This is exactly the same as FIG. 1 except that two large cylindrical electrodes 1b are used. When the columnar electrode is used as described above, the discharge treatment can be continuously performed without damaging the porous body.

The discharge processing apparatus of FIG. 3 is exactly the same as that of FIG. 1 except that a belt-shaped electrode 1a and one columnar electrode 1b are used as electrodes carrying dielectrics 2a and 2b. This discharge treatment device can also perform discharge treatment continuously without damaging the porous body.

The discharge processing apparatus of FIG. 4 is exactly the same as that of FIG. 1 except that five cylindrical electrodes 2a and a belt-like electrode 2b are used as electrodes for supporting the dielectrics 1a and 1b. This discharge treatment device can also perform discharge treatment continuously without damaging the porous body.

In the discharge treatment apparatus shown in FIG. 5, not only a dielectric (hereinafter, referred to as an "opposite dielectric") is carried on the opposing surface of each flat electrode, but also a dielectric is provided on the side wall of each flat electrode. Except that a body (hereinafter, referred to as a “sidewall dielectric”) is supported, it is exactly the same as FIG. Since this discharge processing device carries the side wall dielectrics 3a and 3b, it is possible to prevent discharge between the side walls of the plate electrodes 1a and 1b and the opposing dielectrics 2a and 2b. The material forming the side wall dielectrics 3a and 3b is the opposite dielectric 2a,
It can be made of the same material as 2b. Further, the opposing dielectrics 2a, 2b and the sidewall dielectrics 3a, 3b need not be made of the same material, but may be made of different types of materials. Further, the opposing dielectrics 2a, 2b
And the side wall dielectrics 3a and 3b are separated from each other,
It may be in an integrated state.

The discharge processing apparatus shown in FIG.
It is exactly the same as FIG. 5 except that a belt-shaped thing is used as b. This discharge processing device can prevent discharge between the side walls of each of the flat electrodes 1a and 1b and each of the opposed dielectrics 2a and 2b, and can continuously perform discharge processing without damaging the porous body. Can be implemented.

In a state where the porous body is sandwiched between the opposed dielectrics of such a discharge treatment apparatus, an AC voltage is applied between the electrodes carrying the dielectric to generate a discharge in the internal gap of the porous body. To process.

[0028] The state in which the porous body is sandwiched between the opposing dielectrics in this discharge treatment apparatus means that the opposing dielectric is brought into close contact with the porous body, and substantially between the opposing dielectric and the outer surface of the porous body. In which no space is formed. With such a state, the discharge can be efficiently generated inside the porous body, and the porous body can be processed.

[0029] The AC voltage applied between the electrodes of such a discharge processing apparatus cannot be limited because it depends on the distance between the electrodes (including the opposing dielectric) and the type of gas, but discharge is likely to occur. as such, preferably at 0.25 kV _P or more, and more preferably 0.5 KV _P or more. The unit “KV _P ” indicates a voltage difference from the maximum value peak of the AC voltage to 0. On the other hand, the upper limit of the AC voltage is not limited as long as the voltage does not cause damage to the porous body.

The frequency of the AC voltage 0.1KH _Z ~100
KH _Z is preferred. When the frequency is less than 0.1KH _Z, tend to discharge treatment efficiency is lowered, 100K
Exceeding the H _Z, because there is a fear that the porous body is destroyed by a heated state by dielectric heating, preferably 0.5
KH _{Z ~50KH Z,} more preferably 1KH _Z ~50KH _Z
It is.

The waveform of the applied voltage may be, for example, a sine wave, a triangular wave, a rectangular wave, or a pulse wave. Among them, the pulse wave is preferable because it suppresses heat generation and spark discharge and hardly damages the porous body. In particular, when the discharge treatment is performed while moving the porous body using the discharge treatment apparatus as shown in FIG. 5, the rise is fast (1 microsecond or less) so that damage to the porous body can be suppressed. Pulse waves are preferred. Therefore, it is preferable to use an impulse power supply or a pulse power supply.

The application of such an AC voltage can be performed under atmospheric pressure in the presence of oxygen (for example, in the presence of air), or under atmospheric pressure and in the absence of oxygen (for example, helium). , In the presence of an inert gas such as argon), but from the viewpoint of workability, the former is preferably carried out under the atmospheric pressure and in the presence of oxygen. In the case where the process is performed in the absence of oxygen, for example, a unit capable of supplying an inert gas (eg, a pipe) or a unit capable of retaining the inert gas (eg, a chamber) is provided. Is preferred.

[0033] The application time of the AC voltage in the present invention is not particularly limited, but when it is carried out under the atmospheric pressure and in the presence of oxygen, the amount of peroxide is large and within 60 seconds so that the reactivity is high. Preferably, it is within 30 seconds, more preferably within 20 seconds, and most preferably within 15 seconds. Conversely, the time is preferably 0.1 second or more so that peroxide can be generated.

[0034] As described above, the AC voltage is applied between the electrodes to generate a discharge in the internal space of the porous body to process the porous body. Since this discharge occurs in the internal voids of the porous body, the outer surface of the porous body that is in contact with the opposing dielectric tends to be difficult to be treated. However, since the area of the outer surface of the porous body is very small in view of the total surface area of the material constituting the inside of the porous body, it is considered that the outer surface and the inside of the porous body are substantially treated. Can be.

Next, the treated porous body is brought into contact with the above-mentioned radically polymerizable monomer to form a polymerized layer of the monomer on the outer surface and inside of the porous body, thereby obtaining a modified porous body. Can be manufactured.

Examples of a method of contacting the treated porous body with a radically polymerizable monomer include a method of applying or spraying a solution containing a radically polymerizable monomer on the treated porous body, and a method of contacting a radically polymerizable monomer. Or a method in which the treated porous body is contacted with a vapor of a radically polymerizable monomer.

When the porous body subjected to the discharge treatment as described above is brought into contact with a radically polymerizable monomer, the radically polymerizable monomer is polymerized to form a polymerized layer of the monomer on the outer surface and inside the porous body. I do. As described above, since the discharge occurs in the internal voids of the porous body, the radically polymerizable monomer is easily polymerized inside the porous body,
In the vicinity of the outer surface of the porous body which is in contact with the opposing dielectric, the radically polymerizable monomer tends to hardly polymerize. Therefore, in the modified porous body produced by such a method, the polymerization amount of the monomer near the outer surface (per unit volume) is equal to or less than the polymerization amount of the monomer inside (per unit volume).

Hereinafter, examples of the modified porous body of the present invention will be described, but the present invention is not limited to the following examples.

[0039]

(Example 1) As a porous body, a dividable fiber composed of polypropylene and polyethylene was wet-processed as a porous body, and then entangled with a water stream. At the same time, the dividable fiber was converted into an ultrafine polypropylene fiber and an ultrafine polyethylene fiber. Three divided nonwoven fabrics (porosity: 70%, average pore diameter: 7 µm, thickness: 200 µm, surface density: 60 g / m ² ) were prepared. The air permeability when three nonwoven fabrics are laminated is 5.
It was 56 ml / cm ² · second.

As a discharge treatment device, as shown in FIG. 1, non-porous polytetrafluoroethylene sheets (size: 180 mm × 350) are used as opposed dielectrics 2a and 2b.
mm, thickness: 0.1 mm), and a plate-like electrode 1a, 1b made of a stainless steel plate (150 mm x 300 mm) was provided so as to face each other. In addition, one flat electrode 1a was connected to the sine wave power supply 4, and the other flat electrode 1b was grounded.

Next, the opposing dielectrics 2a, 2b of this discharge device
Thus, in a state where a laminate in which three nonwoven fabrics are stacked is sandwiched, the plate electrodes 1a, 1a,
sinusoidal alternating voltage between b (AC voltage 10 KV _P, Frequency:
20 kHz _Z, output 800 W) is applied to generate discharge in internal voids of the nonwoven fabric was treated for 10 seconds.

Thereafter, the amount of peroxide in the nonwoven fabric constituting the surface layer of the laminate and the nonwoven fabric constituting the intermediate layer was determined as follows:
Vol. 48, No. 9, pp. 535-539
As measured by DPPH described in (1991), the nonwoven fabric constituting the surface layer and the nonwoven fabric constituting the intermediate layer were 2.68 × 10 ¹³ / m ² .

It is known that the greater the amount of peroxide, the greater the amount of radically polymerizable monomer. Therefore, if the discharge-treated porous body is contacted with a radically polymerizable monomer, It is possible to produce a modified porous body in which the polymerization amount (per unit volume) of the monomer near the outer surface is equal to or less than the polymerization amount (per unit volume) of the monomer inside.

(Examples 2 to 13) The same nonwoven fabric as in Example 1 was subjected to discharge treatment, the output of the sine wave power supply 4 was changed as shown in Table 1, and the discharge treatment time was as shown in Table 1. After the discharge treatment was performed in exactly the same manner as in Example 1 except that the amount was changed to 1, the amount of peroxide was measured in the same manner as in Example 1. The results were as shown in Table 1. From Table 1, it was found that the shorter the discharge treatment time, the larger the peroxide amount, that is, the larger the polymerization amount of the monomer. The output of the discharge device is 300
It was also found that about 700 W was appropriate.

[0045]

【table 1】

(Example 14) One nonwoven fabric as in Example 1 was subjected to discharge treatment in the same manner as in Example 1, and the treated nonwoven fabric was immersed in a degassed aqueous solution of acrylic acid monomer (concentration: 60%). Then, excess acrylic acid monomer aqueous solution was squeezed out between the rolls. Next, the nonwoven fabric carrying the aqueous acrylic acid monomer solution is polymerized by heat treatment at 60 ° C. for 4 hours, washed with water, and dried to obtain a modified polymer having a polymerized layer of polyacrylic acid near and inside the outer surface of the nonwoven fabric. A non-woven fabric was manufactured. The polymerization amount of this polyacrylic acid was 5% by weight (3 g / m ² ) of the areal density of the nonwoven fabric. Even if this modified nonwoven fabric is boiled in water for 1 hour,
There was no change in weight after boiling for hours. When the modified nonwoven fabric, the modified nonwoven fabric after boiling with water, and the modified nonwoven fabric after boiling with an aqueous potassium hydroxide solution were immersed in water, all of them were instantaneously wetted.

[0047]

The modified porous material of the present invention is a modified porous material having a polymerized layer of a monomer on the outer surface and inside of the porous material. Is less than or equal to the polymerization amount (per unit volume) of the monomer inside the modified porous body. As described above, the polymer has a polymerized layer on the outer surface and inside of the porous body, and unlike the conventional modified porous body, the monomer is polymerized uniformly throughout the porous body, or rather, on the inside. It is a modified porous body in which more monomer is polymerized.

[0048] In the method for producing a porous body according to the present invention, the electrode supporting the dielectric is placed in a state in which the porous body is sandwiched by the dielectric of a discharge treatment apparatus in which the dielectrics are opposed to each other. An AC voltage is applied between the electrodes supporting the body, a discharge is generated in the internal voids of the porous body, and the porous body is treated with a radical polymerizable monomer. This is a method in which a polymerized layer of a monomer is formed on the outer surface and inside of the body, and the modified porous body as described above can be easily produced.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a discharge treatment device that can be used in the present invention.

FIG. 2 is a schematic cross-sectional view of another electric discharge processing apparatus that can be used in the present invention.

FIG. 3 is a schematic cross-sectional view of still another discharge treatment apparatus that can be used in the present invention.

FIG. 4 is a schematic cross-sectional view of still another discharge treatment apparatus that can be used in the present invention.

FIG. 5 is a schematic cross-sectional view of still another electric discharge processing apparatus that can be used in the present invention.

FIG. 6 is a schematic cross-sectional view of still another electric discharge processing apparatus that can be used in the present invention.

[Explanation of symbols]

 1a, 1b Electrodes 2a, 2b Opposing dielectrics 3a, 3b Sidewall dielectrics 4 AC power supply 5 Porous material

Claims (3)

[Claims] 1. A modified porous body having a polymerized layer of a monomer on the outer surface and inside of the porous body, and the polymerization amount (per unit volume) of the monomer near the outer surface of the modified porous body is: A modified porous body, wherein the amount is equal to or less than the polymerization amount (per unit volume) of a monomer inside the modified porous body. 2. An AC voltage is applied between the electrodes carrying the dielectric while the porous body is sandwiched by the dielectric of the discharge treatment device in which the electrodes carrying the dielectric are arranged so that the dielectrics face each other. Is applied to generate a discharge in the internal voids of the porous body, and then the treated porous body is contacted with a radically polymerizable monomer to form a monomer on the outer surface and inside of the porous body. A method for producing a modified porous body, comprising forming a polymer layer. 3. The method according to claim 2, wherein an AC voltage is applied between the electrodes carrying the dielectric to generate a discharge in the internal voids of the porous body and the processing time is within 60 seconds.
A method for producing the modified porous body according to the above.