JPH0572937B2 - - Google Patents

Description

[Detailed description of the invention]

A. Industrial Application Field The present invention relates to a composition comprising a polyvinyl alcohol resin and having excellent water resistance. B. Conventional technology Polyvinyl alcohol (hereinafter abbreviated as PVA) has been widely used as various binders, adhesives, and surface treatment glues, and is superior to other glues in terms of film-forming properties and strength. It is known to have excellent performance. However, since PVA is water-soluble, it has the disadvantage of low water resistance, particularly when drying at low temperatures, and various methods have been studied to improve this problem. For example, a method of crosslinking PVA with glyoxal, glutaraldehyde, dialdehyde starch, etc., or a method of crosslinking with an alkali metal tetraborate salt, etc. is known. However, in order to make PVA sufficiently water resistant using the former method, it is necessary to heat treat it at a high temperature of 100℃ or higher, particularly 120℃ or higher, for a long period of time, and in order to make it water resistant by drying at a low temperature, for example, a strong acid with a pH of 2 or less is required. It is also known to use aqueous conditions, but in this case there are problems such as poor viscosity stability of the PVA aqueous solution and gelation during use. Furthermore, the latter method has the disadvantage that not only the water resistance obtained is insufficient, but also the viscosity stability of the PVA aqueous solution is poor. In addition, as a method for creating dialysis membranes in a laboratory,
A chitosan-based compound with a high degree of polymerization dissolved in an acetic acid aqueous solution and PVA or the chitosan-based compound
A film is made from a dilute solution using a combination of PVA and glutaraldehyde, and then immersed in a strong alkaline aqueous solution to convert the amino groups in the ammonium-formed chitosan compound into amines with acetic acid. A method has also been proposed in which a cold water-insoluble film is obtained by making PVA itself water-insoluble and highly saponifying PVA.
However, the chitosan-based compounds that have been used in the past, that is, the chitosan-based compounds produced by normal methods, have a molecular weight of several hundred thousand [1% measured with a Bruckfield viscometer (hereinafter abbreviated as B-type viscometer)].
The viscosity of the aqueous solution at 20°C is 500 centipoise or more (hereinafter centipoise is abbreviated as cp)], which is a high degree of polymerization. When used in combination with a PVA aqueous solution, the viscosity becomes extremely high and it cannot be handled unless it is a dilute solution. Currently, it has the disadvantage that it does not become water-insoluble unless it is treated with an alkali because of its insufficient compatibility with water, and it cannot currently be used for industrial purposes. C Problems to be Solved by the Invention The purpose of the present invention is to provide a composition made of a PVA resin that has excellent water resistance not only to cold water but also to hot water, even when dried or heat treated at a relatively low temperature. Our goal is to provide the following. D. Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors found that (A) polyvinyl having a content of copolymer components of 1 mol% or less and a degree of saponification of 70 mol% or more; Alcohol-based resins (excluding polyvinyl alcohol-based resins containing silicon in the molecule), (B) viscosity of 1% by weight aqueous solution at 20°C of 70 centipoise or less, and amino groups per glucose unit (ammonium The component (A) consists of a mixed aqueous solution of a chitosan-based compound with a content of 40 mol% or more (including those converted into groups) and (C) a polyvalent aldehyde containing two or more aldehyde groups in one molecule. and (B) component weight ratio [(A)/(B)] is 99/1~
10 to 90, the polymerization blending ratio of component (C) {[(A)+(B)]/
(C)} of 100/1 to 100/20, a composition with excellent water resistance was discovered, and the present invention was completed. The PVA resin (excluding PVA resins containing silicon in the molecule) used in the present invention refers to ordinary unmodified PVA or modified PVA containing 1 mol % or less of a copolymer component. These modified PVA include anion-modified PVA such as carboxyl group-modified PVA, sulfonic acid group-modified PVA, and phosphate group-modified PVA.
PVA, cation-modified PVA, or modified PVA obtained by copolymerizing ethylene, vinyl ether having a long-chain alkyl group, vinyl ester, (meth)acrylamide, alpha olefin, etc. can also be used. The degree of polymerization of these PVA resins is not particularly limited, but is usually selected from the range of 100 to 3000, and the degree of saponification is selected from the range of 70 to 100 mol%. The chitosan-based compounds used in the present invention refer to chitosan containing 40 mol% or more of amino groups per glucose unit, or derivatives of chitosan in which some or all of these amino groups have been converted to ammonium groups with an acid. say. The degree of polymerization of the chitosan-based compound is such that the viscosity of a 1% aqueous solution at 20°C (hereinafter, the viscosity of an aqueous solution of a chitosan-based compound means the viscosity of an aqueous solution or an acidic aqueous solution measured by a B-type viscometer) is 70 cp or less. As such, it is necessary to use a polymer having a low degree of polymerization which has been subjected to a special depolymerization treatment, and a polymer having a polymerization degree of 1 to 30 cp is more preferable, and a polymer having a polymerization degree of 1 to 10 cp is most preferably used. The above-mentioned chitosan-based compounds used in the present invention are made from, for example, chitin, which is deacetylated to chitosan by the usual method of heterogeneous alkali treatment, and then further subjected to alkali treatment, acid treatment, or peroxide treatment. Therefore, it can be produced by depolymerizing to a high degree, or by deacetylating and depolymerizing chitin in a homogeneous system in a solvent with alkali treatment, etc., and optionally further performing acid treatment or peroxide treatment. . Among the above-mentioned chitosan-based compounds, if the amino groups have not been converted to ammonium salts, they are generally insoluble in water. It is necessary to dissolve the amino group, but if the amino group is converted to an ammonium salt, or if it is produced in the homogeneous system described above and the amino group content is 40 to 60%.
In the case of , it can be dissolved in water as is. The acid used in the above-mentioned dissolution is not particularly limited, but acetic acid, formic acid, citric acid, fumaric acid, maleic acid, sulfamic acid, hydrochloric acid, phosphoric acid, sulfuric acid, etc. are usually used. Specific examples of the polyvalent aldehyde containing two or more aldehyde groups in one molecule used in the present invention include polyvalent aldehydes such as glyoxal, glutaraldehyde, and dialdehyde starch. Among the above-mentioned polyaldehydes, glyoxal is preferred in terms of ease of use (odorless, viscosity stability, etc.) and water-resistant effect of the coating solution made of PVA resin, chitosan compound, and polyaldehyde used in the present invention. Preferably used. In the composition of the present invention having excellent water resistance, it is also effective to use a water-soluble metal salt in addition to the above-mentioned polyhydric aldehyde. Water-soluble metal salts used in this case include aluminum, iron,
Examples include chlorides or sulfates of copper, zinc, tin, titanium, nickel, magnesium, vanadium, chromium, zircon, and the like. Among the metal salts mentioned above, aluminum chloride, aluminum sulfate, potassium alum, ammonium alum and the like are preferably used from the viewpoint of water resistance. In the composition of the present invention with excellent water resistance (A)
The weight blending ratio [(A)/(B)] of PVA resin and (B) chitosan compound is 99/1 to 10/99, preferably 95/
The ratio is 5 to 50/50, more preferably 90/10 to 60/40. Also, the weight blending ratio of (C) polyhydric aldehyde {[(A)
+(B)]/(C)} is 100/1 to 100/20. (A)／(B)
If it exceeds 99/1, there is no water resistance effect and the rating is 10/1.
If it is less than 90, the strength of the resulting film decreases, which is not preferable. Also, [(A)+(B)]/(C) is 100/
If it exceeds 1, the water resistance effect is low, 100/20
If it is less than 20%, the viscosity stability will be poor when the composition of the present invention is used as an aqueous solution. The composition of the present invention having excellent water resistance is as described above (A).
The essential conditions are that it contains a PVA resin, (B) a chitosan compound whose viscosity at 20°C in a 1% aqueous solution is 70 cp or less, and (C) a polyvalent aldehyde, but other than that, depending on the application. A solvent, various additives, other water-soluble resins, polymer aqueous dispersions, etc. can be contained. Water is used as a solvent, but it can also be used in combination with various solvents such as alcohols, ketones, dimethylformamide, dimethyl sulfoxide, etc.Additives include various antifoaming agents, various dispersants, nonionic Alternatively, anionic surfactants, silane coupling agents, PH regulators, etc. may be used. Examples of water-soluble resins include cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, poly(meth)acrylic acid, polyhydroxy(meth)acrylate, and the like. Examples include copolymers, (meth)acrylic polymers such as polyacrylamide, polyvinylpyrrolidone or copolymers thereof, and the like. Furthermore, examples of aqueous polymer dispersions include aqueous dispersions of acrylic polymers and copolymers, ethylene-vinyl acetate copolymers, vinyl ester polymers and copolymers, styrene-butadiene copolymers, and the like. The composition with excellent water resistance of the present invention is used by dissolving or dispersing it in water or water containing the above-mentioned organic solvent, but after forming a film consisting of (A) and (B), (C)
It can also be used by applying. The composition with excellent water resistance of the present invention can be used as an adhesive or binder for inorganic or organic materials, a vehicle for paint, a treatment agent for inorganic or organic materials, by taking advantage of its film-forming properties, film strength, or water resistance.
For example, it is effectively used as a surface coating agent, and is also used in applications where water-soluble resins have conventionally been used, such as films and sheets. E. Effects and Effects of the Invention Although the reason why the water-resistant composition of the present invention has excellent film-forming properties, film strength, and water resistance is not fully elucidated, the water-resistant composition of the present invention has Chitosan-based compounds that can be used in compositions with excellent strength, especially low-viscosity chitosan-based compounds, are PVA.
It is presumed that the chitosan-based compound or the chitosan-based compound and the PVA-based resin are easily crosslinked by the polyvalent aldehyde, resulting in high film strength and water resistance. The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto. In the examples, "%" and "part" are based on weight unless otherwise specified. Example 1 100 parts of PVA (Kuraray Poval PVA105) with a degree of polymerization of 550 and a degree of saponification of 98.5 mol% and 20 parts of a 1% aqueous solution
Viscosity at °C (viscosity measured by BL type viscometer) is 5 cp
After preparing a 15% aqueous solution by dissolving 10 parts of chitosan with an amino group content of 80 mol% per glycol unit in an acetic acid aqueous solution, 5 parts of glyoxal was added as a solid content to prepare an aqueous solution of a water-resistant composition. Created {(A)/(B)=91/9, [(A)+(B)]/(C)=100/
4.5}. This solution was cast and dried at 50°C to produce a sheet-like product. The obtained sheet-like material was immersed in 40°C warm water for 24 hours, and the state of the sheet-like material was observed.
The results are shown in Table 1. Examples 2 to 6 The same procedure as in Example 1 was carried out except that the weight mixing ratio of PVA and chitosan compound used in Example 1 was changed as shown in Table 1. The results are shown in Table 1. Comparative Example 1 The same procedure as in Example 1 was carried out except that the chitosan-based compound used in Example 1 was not used. The results are shown in Table 1. Comparative Example 2 The same procedure as in Example 1 was carried out except that glyoxal was not used in the example. The results are shown in Table 1. Comparative Examples 3 to 4 Same as Example 1 except that instead of the blending ratio of PVA resin and chitosan compound used in Example 1, the blending ratio (A)/(B) was changed as shown in Table 1. I did the same. The results are shown in Table 1. Comparative Example 5 The same procedure as in Example 1 was carried out, except that instead of the chitosan-based compound used in Example 1, a chitosan-based compound having a 1% aqueous solution having a viscosity of 700 cp at 20°C was used. In this case, the solution had a very high viscosity and a gel-like appearance. The results are shown in Table 1. As shown in Table 1, the water-resistant composition of the present invention
It can be seen that the water resistance is extremely excellent even when drying at a relatively low temperature of °C.

[Table] Examples 7 to 8 (A) 100 parts of modified PVA containing 0.5 mol% of cationic group units, a degree of polymerization of 1750, and a degree of saponification of 98.5 mol%.
(B) 15 parts of a chitosan-based compound converted into an ammonium salt by glycolic acid and having an amino group content of 90% and a viscosity of a 1% aqueous solution at 20°C as shown in Table 2 are dissolved in water. A 15% aqueous solution was prepared. After adding polyhydric aldehyde (C) as shown in Table 2 to this solution, it was cast and dried at 50°C to produce a sheet-like product. This sheet-like material was immersed in water at 40°C for 24 hours, and the state of the sheet-like material was observed.
The results are shown in Table 2. Comparative Example 6 The same procedure as in Example 7 was conducted except that the amount of glyoxal used in Example 7 was replaced by the amount shown in Table 2. The results are shown in Table 2. Comparative Example 7 The same procedure as in Example 7 was conducted except that the amount of glyoxal used in Example 7 was replaced by the amount shown in Table 2. In this case, the addition of glyoxal resulted in gelation within a short period of time, and a sheet-like material could not be obtained.

【table】

[Table] Example 9 10 parts of the chitosan-based compound used in Example 7 and 90 parts of PVA with a degree of polymerization of 550 and a degree of saponification of 88 mol% were dissolved in water to prepare 1000 parts of a 10% aqueous solution. To this aqueous solution were added 200 parts of clay and 5% glyoxal based on the total amount of PVA and chitosan compounds, followed by casting and drying at 100° C. for 1 hour to obtain a sheet-like product.
This sheet-like material was insoluble in hot water at 95°C and maintained a firm film shape. Comparative Example 8 The same procedure as in Example 9 was carried out except that the chitosan-based compound used in Example 9 was not used. This sheet-like material was redissolved within a short time in hot water at 40°C and hot water at 95°C.

Claims (1)

[Claims] 1 (A) Polyvinyl alcohol resin with copolymerization component content of 1 mol% or less and saponification degree of 70 mol% or more (excluding polyvinyl alcohol resins containing silicon in the molecule), (B) 1% by weight aqueous solution Viscosity at 20°C of 70 centipoise or less and amino group (including amino groups converted to ammonium groups by acid) content per glucose unit.
It consists of a mixed aqueous solution of 40 mol% or more of a chitosan-based compound and (C) a polyhydric aldehyde containing two or more aldehyde groups in one molecule, and the weight blending ratio of components (A) and (B) [(A )/(B)] is 99/1~10~90,
The polymerization blending ratio of component (C) {[(A)+(B)]/(C)} is 100/
A composition with excellent water resistance of 1 to 100/20.