JPH0432737B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sheet-like waterproof material having air permeability and moisture permeability. Conventionally, methods for imparting air permeability and/or moisture permeability to sheet-like waterproof materials include a method of coating or laminating a continuous microporous membrane on a base fabric, and a method of using water-absorbing and swelling fibers in the threads constituting the base fabric. is known. In the former method, by forming pores that are larger than gaseous water molecules and smaller than liquid water (aggregation of water molecules), waterproofness (water pressure resistance of 600 mm H ₂ O or more) and moisture permeability (moisture permeability) are achieved.
5000g/ ^m2・1 day or more), but sufficient ventilation (airflow rate 0.1cc/ ^cm2・1 day or more) can be satisfied at the same time.
seconds) cannot be granted. In general, air permeability and moisture permeability are often confused as the same property, but the required levels for both properties are vastly different and must be clearly distinguished. Converting the amount of moisture permeation into the unit of molecular flow rate, 5000g/ ^m2・1 day is 3.215×
10 ^-7 mol/cm ²・sec. On the other hand, when converting the amount of ventilation into the unit of molecular flow rate, 0.1 cc/cm ² ·sec becomes 4.160×10 ^-6 mol/cm ² ·sec. By substituting these values and the measurement conditions for moisture permeation and air permeability into the formula for calculating the permeability coefficient, the moisture permeability
The permeability coefficient to achieve 5000g/ ^cm2・1 day is
In order to achieve 1.313×10 ^-9 cm and an air flow rate of 0.1 cc/cm ² ·sec, the permeability coefficient is required to be 5.766×10 ^-8 cm (a calculation example will be described later). This shows that the required level of breathability is 43.9 times higher than the required level of moisture permeability. Also, water pressure resistant
Since the wet air permeability coefficient of 600mmH ₂ O cotton canvas No. 9 is 3.460 x 10 ^-9 cm, it has a water pressure resistance of 600mm.
The permeability coefficient corresponding to H ₂ O or more must be less than or equal to 3.460×10 ^-9 cm. The formula representing the transmission coefficient is:
Equation of Poiseuille flow of gas molecules q=r ⁴ ε(p ² / ₁ − ^{p 2} / ₂ )/8ηlRT r: pore diameter (cm) ε: porosity (pieces/cm ² ) l: film thickness (cm) Therefore, the transmission coefficient p can also be expressed as p=εr ⁴ /l, and since this is expressed as a variable only for the structure of the sheet material, it has a value specific to the structure. Therefore, if the structure remains unchanged, there is no range of permeability coefficients that can simultaneously satisfy the three required levels of air permeability, moisture permeability, and waterproofness. Therefore, the latter method is promising, in which the structure (particularly the pore size) can be changed by water absorption and swelling of the fiber threads. However, in the latter method, the main emphasis is placed on increasing the water absorption and swelling properties of the fibers, so that too many hydrophilic groups are introduced into the fiber yarns, and in some cases, the hydrophilic groups become extremely localized on the filament surface. As a result, when water absorbs and swells, the penetrating action of water molecules increases, and in order to provide sufficient waterproofness, the pore size (in the case of woven/knitted materials, hereinafter referred to as fiber space and
The thread space is called a "hole", and "pore diameter" means the average pore diameter when the "hole" is considered as a circle)
needs to be made smaller. However, with conventional fabrics using water-absorbing and swelling fiber threads, even if they have a structure that provides sufficient air permeability and can reduce the pore size through water absorption and swelling to provide sufficient waterproof properties, the penetration by hydrophilic groups is limited. Due to this effect, sufficient waterproofing is not achieved in practice. In addition, due to moisture absorption, the pore size becomes smaller and the interaction between water molecules and fibers becomes even stronger, so most water molecules cannot pass through in the gaseous state, but pass through the process of adsorption, penetration, and dissipation in the liquid state. . Therefore, the amount of moisture permeable is considerably smaller than that of a hydrophobic sheet material having the same pore size. Furthermore, since the water retention rate becomes very high, the weight increase when wet becomes too large, resulting in poor workability. Furthermore, in order to increase the durability of the sheet-like material as a whole, the base fabric is generally coated with a resin, but in this case, if the coating resin film does not have sufficient air permeability, the sheet-like material as a whole will deteriorate. Naturally, the breathability will be insufficient, making it impossible to obtain a sheet-like breathable, moisture-permeable, and waterproof material. However, even if the material has sufficient breathability, the water absorption and swelling ability of the base fabric will be significantly inhibited, making it impossible to obtain waterproofing. Sexuality becomes insufficient. Therefore, currently, this type of sheet-like material has waterproof properties due to the impermeable (but still moisture permeable) resin membrane, and anti-condensation properties due to the base fabric that has moisture absorption properties (water absorption and swelling ability is inhibited). It can be called a waterproof sheet-like material that prevents condensation. Because the base fabric is hygroscopic, it shows high values when measured in accordance with JIS-Z-0208 "Moisture permeability test method for moisture-proof packaging materials," and for this reason it is called a "moisture-permeable waterproof membrane material." This is due to inappropriate selection of the measurement method. On the other hand, cotton canvas has breathability and moisture permeability depending on the product number, but its strength and water pressure resistance are inferior to synthetic fiber canvas, and it also has drawbacks such as being too heavy and sagging when wet. It also has poor durability. The inventors of the present invention have conducted intensive studies on a sheet-like waterproof material that does not have the above-mentioned drawbacks and has excellent air permeability and moisture permeability, and have discovered the present invention. That is, the sheet-like breathable and moisture-permeable waterproof material of the present invention is a composite sheet-like material of a sheet-like base material having water-absorbing and swelling properties and a resin membrane or film made of a polymer containing a polyamino acid. P is a measure of the ease with which molecules permeate through a material (hereinafter referred to as permeability coefficient) using the following formula: P=8qηRT/P ₁ ² −P ₂ ² P: Permeability coefficient (cm) q: Molecular flow rate (mol/cm ²・sec) η: Molecular viscosity (poise) R: Gas constant (cm ³ dyne/cm ²・K mol) T: Temperature (K) P ₁ : Partial pressure of molecules on the high pressure side (dyne/cm ² ) P ₂ : Partial pressure of molecules on the low pressure side (dyne/cm ² )", the air permeability coefficient P _D when the sheet-like material is dry, the air permeability coefficient P _W when the sheet-like material is wet, and The ratio (hereinafter referred to as bubble capacity) V satisfies the following formula: V=P _D /P _W ≧30, and the ratio _H between P _D and the permeability coefficient of water molecules (hereinafter referred to as hydrophilicity) H satisfies the following formula: H= It is characterized by satisfying P _D /P _H ≦V. The sheet-like material according to the present invention is a composite sheet composed of a water-absorbing and swelling sheet-like base material and a resin membrane or film made of a polymer containing polyamino acids, as described below. It is necessary that the valve capacity V is 30 or more, more preferably 100 or more. Valve capacity V
is less than 30, if the structure has a ventilation rate of 0.1cc/cm ² · seconds or more, the water pressure resistance will be 600mmH ₂ O or less, and conversely, if the structure has a water pressure resistance of 600mmH ₂ O or more, the ventilation The amount is less than 0.1cc/cm ² ·sec, making it impossible to satisfy both breathability and waterproof properties at the same time. If the valve capacity V is 30 or more, if the structure of the sheet material is designed to provide sufficient air permeability when it dries, the pore size will satisfy the waterproof property when wet due to rain etc. due to water absorption and swelling. Therefore, as long as the hydrophilic capacity H is equal to or less than the valve capacity V, both breathability and waterproof properties can be satisfied at the same time. The hydrophilic capacity H of the sheet material according to the present invention needs to be the bulb capacity V. When the hydrophilic capacity H is larger than the valve capacity V, the degree of decrease in waterproofness due to the water penetration effect of the hydrophilic group is large;
Even if the pore diameter is reduced by the valve action to improve waterproofness, sufficient waterproofness cannot be maintained. In addition, as the pore size decreases due to moisture absorption, the interaction between water molecules and the sheet-like constituent material (fabric or base film) increases, and most water molecules cannot pass through in the gaseous state, but in the liquid state. In this case, the rate of adsorption is fast, but the rate of permeation and dissipation is extremely slow compared to the rate of permeation of gaseous water molecules, and the process of permeation and dissipation is repeated. Moisture permeability cannot be achieved. Furthermore, since the weight increases significantly due to water absorption, there are problems in terms of workability when used in sheet-like waterproof materials, etc., and when used in waterproof clothing, etc., the disadvantage is that it feels heavy to wear. It also becomes. When the hydrophilic capacity H is less than or equal to the valve capacity V, there is some increase in water permeability due to the hydrophilic group, but the decrease in waterproofness due to this is compensated for by the improvement in waterproofness due to the reduction of the pore diameter. can,
It can maintain the waterproofness required as a sheet-like waterproof material. In addition, as the pore size decreases due to moisture absorption, most of the water molecules pass through the pores in a liquid state by repeating the process of adsorption, permeation, and dissipation, but some water molecules still pass through in the gaseous state. Since the interaction between water molecules and the base material is not so large, the permeation rate of water molecules through the sheet-like material as a whole is high enough to maintain sufficient moisture permeability. The fabric or base film used as the base material used in the present invention may be any material as long as it has the ability to swell by water absorption and/or moisture absorption.
Any of natural polymers, modified products thereof, and synthetic polymers may be used. The fabric constituting the base material used in the present invention may be a woven or knitted fabric, and the constituting yarn may be a filament yarn or a spun yarn, either alone, or a mixed or blended yarn. Further, the base film used in the present invention may be a single film or a composite film. Furthermore, the base material may be modified by graft polymerization or the like. Particularly preferably, the base material has a valve capacity V of 30 or more and a hydrophilic capacity H of the valve capacity V
It is preferable that the material has a water absorption and swelling ability of 0.1 cc/cm ² ·sec or more as a base material. This is because the valve capacity V and hydrophilic capacity H, which are the properties of the sheet material of the present invention, are mainly determined by the valve capacity V and hydrophilic capacity H of the base material. In addition, the air permeability of the sheet material is less than the air permeability of the smaller of the air permeability of the base material and the resin membrane (or film), so the air permeability of the base material must be adjusted to ensure sufficient air permeability. Value that can be maintained (0.1cc/
^cm2・sec) or higher is the minimum requirement. The substrate-coating resin membrane or film-constituting resin used in the present invention is not particularly limited to its type, as long as it can form continuous micropores during membrane or film molding. The minimum air permeability of the base coating resin membrane or film used in the present invention is required to be at least a value (0.1 cc/cm ² ·sec) that can maintain sufficient air permeability. One of the major drawbacks of conventional sheet-like waterproof materials using water-absorbing and swelling fabrics is that the fabric is coated with a thick resin film in order to improve the durability of the sheet-like material. Due to this resin film, air permeability was lost, and the water absorbing and swelling properties of the fabric were greatly impaired, leaving only water absorbing and water retaining properties. Therefore, the substrate-coating resin membrane or film used in the present invention has a continuous fine pore size that does not inhibit the water absorption swelling property of the substrate and can change the pore size in accordance with the water absorption swelling and drying shrinkage behavior of the substrate. It is important to have porosity. In the present invention, a polymer containing a polyamino acid is used as a resin capable of forming a resin membrane or film having such performance. In terms of the ability to form continuous micropores whose pore diameter can change according to the water absorption swelling and drying shrinkage behavior of the base material without inhibiting the water absorption swelling properties of the base material, a resin containing polyamino acid alone is most preferable. In order to improve the adhesion to the base material and the texture, it may be blended with a resin such as polyurethane, or may be a copolymer with polyurethane or the like. In the present invention, the polyamino acid is a general term for polymers composed of monomers each having one or more amino groups and one or more carboxyl groups, and may be a homopolymer of a single monomer composition or a random or block copolymer of various monomers. In particular, polyamino acids consisting of acidic amino acids or ω-alkyl esters of acidic amino acids are preferred. Examples of acidic amino acids include aminomalonic acid, aspartic acid, glutamic acid, 2-amino-adipic acid, α-amino-pimelic acid, β-methyl-aspartic acid, β-methylene-aspartic acid,
β, β-dimethyl-aspartic acid, β-phenyl-glutamic acid, γ-methyl-glutamic acid,
α-amino- such as γ-methylene-glutamic acid
digalboxic acid, and β-amino-glutamic acid, β-amino-adipic acid, etc.
Examples include dicarboxylic acids. The alkyl group of the ω-alkyl ester includes methyl, ethyl, 2-
Examples include aminoethyl, 2-hydroxyethyl, 2-chloroethyl, 2-bromoethyl and the like. In addition, the present invention improves air permeability when drying the sheet material.
Since the structure achieves waterproofness when the pore diameter is reduced by water absorption or swelling, initial waterproofness cannot be achieved if a base material or resin film with a slow response speed to water absorption or swelling is used. In this case, by applying a regular water repellent such as fluorine-based or silicone-based to one or both sides of the base material, the water permeation rate can be slowed down and time for water absorption and swelling can be increased, so that the initial waterproofness can be improved. realizable. Next, Examples and Comparative Examples according to the present invention will be shown, but these are not intended to limit the scope of the claims in any way. Example 1 80℃ with 5.0g/aqueous sodium carbonate solution, 1
Acrylic acid 8 treated with water, washed with water, and air-dried
Fabric with a weave density of 54 x 42 threads/inch using yarn (No. 20 Sanko) that is a blend of mol% copolymerized polyacrylonitrile fiber (fineness 1.5d) and 70% by weight polyethylene terephthalate fiber (fineness 2.5d). was woven. The air permeability of this fabric was 0.850 cc/cm ² ·sec. This fabric was coated with a dimethylformamide solution containing 20% by weight of the mole block copolymer of γ-methyl-L-glutamate-N carboxylic anhydride and urethane prepolymer.
After air-drying for 10 minutes, it was immersed in water for a day and night, then washed with water and air-dried to form micropores with continuous pores. The amount of resin deposited was 20% by weight based on the base material. The performance of this sheet-like waterproof material is shown in Table 1, and it was possible to obtain a sheet that satisfies air permeability, moisture permeability, and waterproof properties at the same time. Example 2 Room-temperature curing silicone water repellent (Torre Silicone SD-8000) was applied to one side of the same fabric as in Example 1.
After coating 0.5% by weight, resin coating and continuous pore formation treatment were performed under the same conditions as in Example 1. The performance of this sheet-like waterproof material was as shown in Table 1. Example 3 Saponified polyvinyl alcohol fiber (fineness 1.5d) modified with 35 mol% α-hexadecene was mixed with 70% by weight polyethylene terephthalate fiber (fineness
A fabric with a weave density of 54 x 42 threads/inch was woven using yarn (No. 20 Sanko) blended with 2.5d). The amount of ventilation is
It was 0.575cc/ ^cm2・sec. This fabric was subjected to the same water repellent treatment as in Example 2, and then subjected to the same resin coating and continuous pore forming treatments as in Example 1. The performance of this sheet-like waterproof material was as shown in Table 1. Example 4 Poly-γ-methyl-L was added to the same fabric as in Example 1.
- coated with an ethylene dichloride solution containing 10% by weight of glutamate. After air drying for 5 minutes,
After soaking in methanol for a day and night, it was washed with water and air-dried to form micropores having continuous pores. The amount of resin deposited was 15% by weight based on the base material. The performance of this sheet-like waterproof material was as shown in Table 1. Comparative Example 1 A fabric similar to that of Example 3 was made and subjected to the same treatment, except that no water repellent treatment was performed. The performance of this sheet material was as shown in Table 1. Comparative Example 2 Using a cotton canvas No. 9 greige machine, the same resin coating and continuous pore formation treatments as in Example 1 were performed.
The performance of this sheet material was as shown in Table 1. Comparative Example 3 The same fabric as in Example 1 was coated with polyurethane alone and subjected to the same continuous pore forming treatment as in Example 1. The performance of this sheet material was as shown in Table 1. In the above description, the permeability coefficient, air permeability, moisture permeability, water pressure resistance, tensile strength, and tear strength were calculated or measured using the following methods. Calculation of permeability coefficient Calculation of P _D and P _W : Consider the case of calculating the permeability coefficient of a sheet-like material with an air flow rate of 0.1 cc/cm ²・sec. Each value under the measurement conditions is the viscosity of the molecule η=1800×10 ^-4
Poise, temperature T = 293k, high pressure side molecular partial pressure p ₁ =
1.0133×10 ⁶ dyne/cm ² , low pressure side molecular partial pressure p ₂ =
It is 1.0121×10 ⁶ dyne. Airflow unit cc/
Converting cm ²・sec to molecular flow rate mol/cm ²・sec, 0.1 cc/cm ²・sec is 0.1×273/22.4×10 ³ ×293=4.160×10 ^-6 , so q=4.160×10 ^-6 mol/ ^cm2・sec. If this is substituted into the equation p=8qηRT/(P ² ₁ −P ² ₂ ), p=5.766×10 ⁻⁸ (cm). Here, the gas constant R is 8.314×10 ^-7 cm ³・dyne/
cm ² ·k·mol was used. Calculation of P _H : Consider the case of calculating the permeability coefficient of a sheet-like material with a moisture permeability of 5000 g/m ² per day. Each value under the measurement conditions is the viscosity of the molecule η=1.068×
10 ^-4 poise, temperature T = 313k, high pressure side molecular partial pressure p ₁
=7.377×10 ⁴ dyne/cm ² , low pressure side molecular partial pressure p ₂ =
0dyne/ ^cm2 . The unit of moisture permeability, g/m ²・1 day, is converted to the molecular flow rate mol/cm ²・second, which is 5000.
g/m ² ·1 day is 5000/18×10 ⁴ ×24×60 ₂ =3.215×10 ^-7 , so q=3.215×10 ^-7 mol/cm ² ·sec.
If these values are substituted into the formula for calculating the transmission coefficient P, then p=1.313×10 ⁻⁹ (cm). <Measurement of air permeability> Measurement was performed using a Frazier type tester according to JIS L 1096-1979 A method. <Measurement of moisture permeability> Measured by ASTM E96-66BW method. <Measurement of water pressure resistance> Measured according to JIS L 1092-1972 A method. <Measurement of tensile strength/tear strength> JIS L 1096-1979 A method (strip method)
and A-1 method (single tongue method). 【table】

Claims (1)

[Scope of Claims] 1. A composite sheet-like material of a sheet-like base material having water-absorbing and swelling properties and a resin membrane or film made of a polymer containing polyamino acids, the sheet-like material having easy permeability of molecules. _The scale (hereinafter referred to as permeability ^{coefficient )} P that ^indicates _the (poise) R: Gas constant ( ^cm3・dyne/ ^cm2・K・mol) T: Temperature (K) _P1 : Partial pressure of molecules on the high pressure side (dyne/ ^cm2 ) _P2 : Partial pressure of molecules on the low pressure side The ratio of the air permeability coefficient P _D when the sheet material is dry to the air permeability coefficient P _W when the sheet material is wet (hereinafter referred to as bubble capacity), expressed as partial pressure (dyne/cm ² ). V satisfies the following formula V=P _D /P _W ≧30, and the ratio H between P _D and the permeability coefficient P _H of water molecules (hereinafter referred to as hydrophilicity) satisfies the following formula H=P _D /P _H ≦V A sheet-like breathable, moisture-permeable waterproof material that satisfies the following requirements. 2. Claims in which the composite sheet-like material is a resin film-coated fabric or a composite film obtained by coating or laminating a resin film or film made of a polyamino acid-containing polymer on at least one side of a sheet-like base material having water-absorbing and swelling properties. 1st
The sheet-like breathable, moisture-permeable, waterproof material described in Section 1. 3 The fabric or base film serving as the base material of the composite sheet material has a bubble capacity V of 30 or more and a hydrophilic capacity H
2. The sheet-like breathable and moisture permeable waterproof material according to claim 1, which has a water absorption swelling property of V or less, and has an air permeability as a base material of 0.1 cc/cm ² ·sec or more. 4. The resin membrane or film made of a polymer containing polyamino acids that covers the base material of the composite sheet-like material has continuous micropores with an air permeability of 1 c.c./cm ² · seconds or more, and The sheet-like breathable and moisture-permeable waterproof material according to claim 1, wherein the pore diameter can be changed in accordance with the swelling and shrinking behavior of the base material. 5. The sheet-like breathable and moisture permeable waterproof material according to claim 1, wherein one or both sides of the base material are subjected to water repellent treatment.