JPH06157860A - Water-resistant composition - Google Patents

Abstract

PURPOSE:To obtain a compsn. which is excellent in water resistance even when dried or heat-treated at a relatively low temp. and is colored little even when kept long at high temp. and humidity by compounding a PVA resin with chitosan having a low degree of polymn., an aldehyde compd., a reducing agent, and a free-radical scavenger. CONSTITUTION:This water-resistant compsn. is obtd. by compounding 100 pts.wt. PVA resin with 1-90 pts.wt. chitosan having a viscosity (a 1-wt.% aq. soln. at 20 deg.C of 70cP or lower, 1-20 pts.wt. aldehyde compd., 0.0001-10 pts.wt. reducing agent, and 0.0001-10 pts.wt. free-radical scavenger. The compsn. is very excellent in resistance not only to cold water but also to hot water even when dried or heat-treated at a relatively low temp., colored little even when kept long at high temp. and humidity, and thus excellent in stability of qualities.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water resistant composition having excellent stability.

[0002]

2. Description of the Related Art Conventionally, polyvinyl alcohol (hereinafter,
Polyvinyl alcohol is abbreviated as “PVA”), which is widely used as various binders, adhesives or surface-treating glues, and has excellent performance in film-forming property and strength that other glues cannot follow. Are known. However, since PVA is water-soluble, it has the drawback of being poor in water resistance, especially when dried at low temperatures.
Conventionally, various methods have been studied for the purpose of improving this. For example, a method of cross-linking PVA with glyoxal, glutaraldehyde, dialdehyde starch or the like and a method of cross-linking with alkali metal tetraborate salt or the like are known. However, in order to make PVA sufficiently water resistant by the former method, generally 100 ° C. or higher, especially 120 ° C.
It is necessary to heat-treat at a high temperature of ℃ or more for a long time, and it has been proposed to use strong acidic conditions such as pH 2 or less to make it water resistant by low temperature drying.
In this case, there is a problem that the viscosity stability of the PVA aqueous solution is poor and gelation occurs during use. In addition, in the latter method, the water resistance obtained is insufficient and PVA
It has a drawback that the viscosity stability of the aqueous solution is poor.

Further, as a method for making a dialysis membrane in a laboratory, a film is made from an acidic aqueous solution of acetic acid in which chitosan having a high degree of polymerization and PVA are dissolved or an acidic aqueous solution of acetic acid in which chitosan, PVA and glutaraldehyde are dissolved. , And then dipping in a strong alkaline aqueous solution to convert the amino group in the chitosan that has been ammoniumated by acetic acid into an amine to make the chitosan itself insoluble in water and highly saponify PVA to make it insoluble in cold water. A method for obtaining a film has also been proposed. However, conventionally used chitosan, that is, chitosan produced by an ordinary method has a molecular weight of several hundred thousand [1% by weight aqueous solution measured by a Brookfield viscometer (hereinafter abbreviated as “B type viscometer”). The viscosity at 20 ° C. is 500 centipoise (hereinafter, centipoise is abbreviated as cp) or higher], and therefore has a significantly high viscosity when dissolved in water together with PVA, and cannot be handled unless it is a dilute solution.
Further, since it has insufficient compatibility with PVA, it has a drawback that it becomes water-insoluble unless treated with an alkali as described above.

Further, Japanese Patent Application Laid-Open No. 60-52822 discloses a composition having excellent water resistance, which comprises a polyvinyl alcohol resin, chitosan and an aldehyde compound, but this composition has a problem in stability. That is, the aqueous solution of this composition and the paper coated with it have the drawback of being colored during storage. In addition, JP-A-1-167302
Even when chitosan subjected to the reduction treatment disclosed in US Pat.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to show extremely excellent water resistance not only to cold water but also to hot water even when the composition is dried or heat treated at a relatively low temperature, An object of the present invention is to provide a composition excellent in quality stability with little coloring even when kept under high temperature and high humidity for a long period of time.

[0006]

The above-mentioned problems are solved by the composition of the present invention, that is, (A) PVA resin, (B) chitosan having a viscosity of 70 wt. It is solved by a water resistant composition comprising an aldehyde compound, (D) a reducing agent and (E) a radical scavenger.

The PVA resin used in the present invention may be any water-soluble PVA resin.
In addition to A, carboxyl group-modified PVA, sulfonic acid group-modified PVA, phosphoric acid group-modified PVA, anion-modified PVA or cation-modified PVA or ethylene, vinyl ether having a long-chain alkyl group, vinyl ester, (meth) acrylamide, alpha olefin Modified PVA or the like obtained by copolymerizing the above can also be used. The degree of polymerization of these PVA-based resins is not particularly limited, but is usually 100 to 3,000.
It is selected from the range of 0, and the saponification degree is not particularly limited as long as it is in the water-soluble range, but is usually 70 to 100 mol%.
Selected from the range.

As the chitosan used in the present invention, those containing 40% or more of amino groups per glucose unit, or those in which some or all of these amino groups are converted to ammonium groups by an acid are used. The chitosan has a viscosity (B
It is necessary to have a low degree of polymerization of 70 cp or less (viscosity by a viscometer), more preferably 1 to 30 cp, most preferably 1 to 10 cp.

The above-mentioned low degree of polymerization chitosan used in the present invention is obtained by subjecting chitosan to a special depolymerization treatment. That is, for example, chitin is used as a raw material, and after deacetylation to chitosan by a usual method of alkali treatment in a heterogeneous system, chitosan is further highly depolymerized by alkali treatment, acid treatment or peroxide treatment, or chitin. It can be produced by carrying out deacetylation and depolymerization by alkali treatment or the like in a homogeneous system in the solvent, and optionally further acid treatment or peroxide treatment.

Among the above-mentioned chitosans, those whose amino groups have not been converted to ammonium salts are generally insoluble in water, and therefore, in the presence of an acid to the extent that some or all of these amino groups are converted to ammonium salts. However, in the case where the amino group is converted to an ammonium salt or when the amino group content is 40 to 60% produced by the above-mentioned homogeneous system, it may be dissolved in water as it is. it can. As the acid used when dissolving in water,
There is no particular limitation, but usually lactic acid, acetic acid, formic acid, citric acid,
Fumaric acid, maleic acid, sulfamic acid, hydrochloric acid, phosphoric acid, sulfuric acid, etc. are used.

As the aldehyde compound used in the present invention, any compound which is water-soluble and produces an aldehyde in an aqueous solution can be used. Specific examples thereof include monoforms such as formalin, acetaldehyde, propionaldehyde and butyraldehyde. Aldehydes, glyoxal, glutaraldehyde, polyhydric aldehydes such as dialdehyde starch, condensation products of formalin and ammonia such as hexamethylenetetramine, dimethylol urea, methylol amides such as N-methylol acrylamide, urea formalin resin, melamine formalin resin, etc. Can be mentioned. Of the above-mentioned aldehyde compounds, the ease of use of a coating liquid comprising the PVA resin used in the present invention, chitosan and an aldehyde compound (odorless, viscosity stability, etc.)
And glyoxal or hexamethylenetetramine is preferably used from the viewpoint of water resistance.

In the composition having excellent water resistance of the present invention, it is also effective to use a water-soluble metal salt in combination with the above-mentioned aldehyde compound in order to further improve the water resistance. The water-soluble metal salt used in that case is aluminum, iron, copper, zinc, tin, titanium, nickel,
Examples include chlorides or sulfates of magnesium, vanadium, chromium, zircon and the like. Among the above-mentioned metal salts, aluminum chloride, aluminum sulfate, potassium alum, ammonium alum and the like are preferably used in terms of the water resistance effect.

The reducing agent used in the present invention may be any one if it is water-soluble or water-dispersible, and specific examples thereof include sulfurous acid, sodium hydrogen sulfite, sodium metabisulfite, sodium hydrogen sulfide, cysteine and N-. Acetyl cysteine, thioglycolic acid, thiosalicylic acid,
Examples include hydrazine, semicarbazide, hydroxylamine hydrochloride, and the like.

The radical scavenger used in the present invention may be any water-soluble or water-dispersible agent, and specific examples thereof include hydroquinone, hydroquinone monomethyl ether, hydroquinone dimethyl ether, and pentaerythrityl-tetrakis [3- (3. , 5-di-t-butyl-
4-Hydroxyphenyl) propionate], N, N '
-Hexamethylenebis (3,5-di-t-butyl-4-
(Hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, n-propyl gallate, butylhydroxyanisole , Butylhydroxytoluene, nordihydroguaiaretic acid and the like.

In the water resistant composition having excellent stability of the present invention, PVA resin, chitosan, aldehyde compound,
The compounding ratio of the reducing agent and the radical scavenger is 1 to 90 parts by weight, preferably 1 to 50 parts by weight, and more preferably 1 to 40 parts by weight of chitosan with respect to 100 parts by weight of the PVA-based resin. 1-20 polymer parts, reducing agent 0.0001-10 parts by weight, preferably 0.001-
1 part by weight, and the radical scavenger is 0.0001
10 to 10 parts by weight, preferably 0.001 to 1 part by weight.

If the amount of chitosan is less than 1 part by weight, there is no water resistance effect, and if it exceeds 90 parts by weight, the strength of the film obtained is unfavorable. If the amount of the aldehyde compound is less than 1 part by weight, the water resistance effect is low, and
If it exceeds 20 parts by weight, the viscosity stability will deteriorate when the composition is used as an aqueous solution. When the amount of the reducing agent is less than 0.0001 parts by weight, the effect of preventing coloration is low, and when it exceeds 10 parts by weight, the water resistance effect is deteriorated. If the amount of the radical scavenger is less than 0.0001 parts by weight, the coloring prevention effect is low, and if it exceeds 10 parts by weight, the water resistance effect is deteriorated.

In the composition of the present invention, it is important to use the reducing agent (D) and the radical scavenger (E) together in order to exert an excellent anti-coloring effect. If neither the (D) reducing agent nor the (E) radical scavenger is contained, the yellowing of the aqueous solution and its coated paper with time is remarkable. The same applies when (D) does not contain a reducing agent and only (E) a radical scavenger is contained. (E)
When the radical scavenger is not contained and only the reducing agent (D) is contained, the yellowing of the aqueous solution with time is slightly improved, but the yellowing of the coated paper with time is remarkable.

The water-resistant composition of the present invention has the above-mentioned (A).
In addition to the PVA-based resin, (B) low-polymerization chitosan, (C) aldehyde-based compound, (D) reducing agent, (E) radical scavenger, the water resistance and stability intended by the present invention are not impaired. As long as it is suitable, a solvent, various additives, other water-soluble resins, polymer aqueous dispersions, etc. can be contained. Water is preferably used as the solvent, but a solvent such as various alcohols, ketones, dimethylformamide, dimethylsulfoxide and the like can be used together therewith. Examples of the additives include various defoaming agents, various dispersants, nonionic or anionic surfactants, silane coupling agents, pH adjusting agents and the like. Examples of the water-soluble resin include cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, poly (meth) acrylic acid, polyhydroxy (meth) acrylate or copolymers thereof, (meth) acrylic polymers such as polyacrylamide, polyvinylpyrrolidone or the like. Examples thereof include copolymers. Furthermore, as the polymer aqueous dispersion, acrylic polymers and copolymers, ethylene-vinyl acetate copolymers,
Examples thereof include aqueous dispersions of vinyl ester polymers and copolymers, styrene-butadiene copolymers and the like.

The water resistant composition of the present invention is usually used in a form in which all the components (A) to (E) are dissolved or dispersed in water or water containing the above-mentioned organic solvent. However,
It is also possible to apply the aldehyde compound (C) after forming a film or other molded article from an aqueous liquid of a composition containing the four components (A), (B), (D), and (E). The water resistant composition of the present invention has excellent water resistance and good film-forming property,
Taking advantage of the film strength, it is effectively used as an adhesive or binder for inorganic or organic substances, a vehicle for paints, a treatment agent for inorganic or organic materials, for example, a surface coating agent. It is also used for the applications that have been used.

[0020]

The reason why the composition of the present invention is excellent in water resistance, quality stability, film-forming property, and film strength is not fully understood, but the low viscosity of the composition of the present invention Chitosan is compatible with PVA-based resin at the molecular level, and depending on the aldehyde compound, chitosan or chitosan and P
It is designated as exhibiting high film strength and water resistance because it easily cross-links with VA resin. Further, since the composition contains a reducing agent and a radical scavenger, it reduces the aldehyde group generated during the decomposition of chitosan, and further suppresses the radical reaction that causes coloration over time. It is considered that the aqueous liquid or the paper on which it is coated is prevented from being colored and the stability of quality is improved.

[0021]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In the examples, "%" and "parts" are based on weight unless otherwise specified.

Example 1 100 parts of PVA (Kuraray Poval "PVA105") having a polymerization degree of 550 and a saponification degree of 98.5 mol% and the viscosity of a 1% aqueous solution at 20 ° C. (viscosity measured by a BL type viscometer) are 5c.
10 parts of chitosan having an amino group content of 80% at p was dissolved in an acidic aqueous solution of acetic acid to prepare an aqueous solution having a solid content concentration of 15%, and then 0.5 parts of sodium hydrogen sulfite (reducing agent),
0.5 parts of hydroquinone monomethyl ether and 5 parts of glyoxal were added to prepare an aqueous solution of the water resistant composition. This solution was cast and dried at 50 ° C. to prepare a sheet. The obtained sheet material was immersed in warm water at 40 ° C. for 24 hours, and the state of the sheet material was observed. The results are shown in Table 1.

Examples 2 to 6 An aqueous solution of a water resistant composition was prepared in the same manner as in Example 1 except that the types of PVA resin, reducing agent, radical scavenger and the compounding ratio with chitosan were changed as shown in Table 1. Further, a sheet-like material was prepared and its water resistance was evaluated. The results are shown in Table 1.

Comparative Example 1 Preparation of an aqueous solution of the composition, preparation of a sheet and evaluation of water resistance were carried out in the same manner as in Example 1 except that chitosan was not used. The results are shown in Table 1.

Comparative Example 2 An aqueous composition solution was prepared, a sheet-like product was prepared and water resistance was evaluated in the same manner as in Example 1 except that glyoxal was not used. The results are shown in Table 1.

Comparative Examples 3 to 6 A composition aqueous solution was prepared in the same manner as in Example 1 except that the compounding ratio of the PVA resin, reducing agent, radical scavenger and chitosan used in Example 1 was changed as shown in Table 1. Was prepared, a sheet-like material was prepared, and water resistance was evaluated. The results are shown in Table 1.

Comparative Example 7 Instead of the chitosan used in Example 1, 20% of a 1% aqueous solution was used.
Preparation of an aqueous solution of the water resistant composition, preparation of a sheet-like product and evaluation were carried out in the same manner as in Example 1 except that chitosan having a viscosity at 700 ° C. of 700 cp was used. In this case, the aqueous solution of the composition had a very high viscosity and a gel form. The results are shown in Table 1.

[0028]

[Table 1]

* 1 The PVA resin in Table 1 is as follows. PVA-105: degree of polymerization 550, saponification degree 98.5 mol% PVA-117: degree of polymerization 1750, saponification degree 98.5 mol% PVA-217: degree of polymerization 1750, saponification degree 88 mol% Carboxyl group-modified PVA : Carboxyl group content 1 mol%, degree of polymerization 1750, saponification degree 88 mol% Sulfonic acid group modified PVA: Sulfonic acid group content 1 mol%, degree of polymerization 500, saponification degree 98.5 mol% Cation modified PVA: Cationic group content 0.5 mol%,
Polymerization degree 1750, saponification degree 98.5 mol% As shown in Table 1, the water-resistant composition of the present invention produces a film excellent in water resistance even when dried at a relatively low temperature of 50 ° C. I understand that

Examples 7 to 14 (A) Modified PVA100 containing 0.5 mol% of a cationic group unit and having a polymerization degree of 1750 and a saponification degree of 98.5 mol%.
Part and (B) chitosan 15 having a content of amino groups converted to ammonium salt by glycolic acid of 90% and a viscosity of a 1% aqueous solution at 20 ° C. as shown in Table 2
Parts were dissolved in water to prepare a 15% aqueous solution. A (D) reducing agent, (E) radical scavenger and (C) aldehyde compound as shown in Table 2 were added to this solution, followed by casting and drying at 50 ° C. to prepare a sheet-like material. 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 8 The addition amount of glyoxal used in Example 7 is shown in Table 2.
A composition aqueous solution was prepared, and a sheet-shaped product was prepared and evaluated in the same manner as in Example 7, except that the composition was changed as shown in FIG. The results are shown in Table 2.

Comparative Example 9 The addition amount of glyoxal used in Example 7 is shown in Table 2.
A composition aqueous solution was prepared, and a sheet-shaped product was prepared and evaluated in the same manner as in Example 7, except that the composition was changed as shown in FIG. In this case, addition of glyoxal caused gelation within a short time, and a sheet-like product was not obtained.

[0033]

[Table 2]

Example 15 10 parts of the same chitosan as used in Example 7 and a degree of polymerization of 5
90 parts of PVA having a saponification degree of 88 mol%, 50 parts of sodium bisulfite and 0.1 parts of hydroquinone monomethyl ether were dissolved in water to prepare 1,000 parts of a 10% aqueous solution. After adding 200 parts of clay and 5 parts of glyoxal to this aqueous solution, it was cast and dried at 100 ° C. for 1 hour to obtain a sheet-like material. This sheet-like material was insoluble in hot water at 95 ° C. and maintained a firm film shape.

Comparative Example 10 An aqueous composition solution was prepared, a sheet-like product was prepared and evaluated in the same manner as in Example 15 except that chitosan was not used.
This sheet material was redissolved in 40 ° C. hot water and 95 ° C. hot water in a short time.

Example 16 A sheet-like substance was prepared in the same manner as in Example 1, and the sheet-like substance was stored at 40 ° C. and 90% humidity, and the degree of coloration was initially set after 1 week and after 2 weeks. 3 weeks later, 4 weeks later,
Each measurement was made after 6 weeks. The results are shown in Table 3. In addition, a color difference meter (Z-1001DP, manufactured by JEOL Ltd.) was used for the measurement of coloration, and the value b was evaluated.

Examples 17 to 20 Sheet-like substances were prepared in the same manner as in Examples 2, 3, 9 and 10, and coloration with time was evaluated in the same manner as in Example 16. The results are shown in Table 3.

Comparative Example 11 Example 16 except that the reducing agent and the radical scavenger were not used.
A sheet-like substance was prepared in the same manner as in Example 1 and evaluated for coloring with time in the same manner as in Example 16. The results are shown in Table 3.

Comparative Examples 12 and 13 Example 1 except that the reducing agent and the radical scavenger were not used.
Sheet-like substances were prepared in the same manner as in Nos. 7 and 18, and the coloration with time was evaluated. The results are shown in Table 4.

Comparative Example 14 A sheet-like substance was prepared in the same manner as in Example 19 except that the reducing agent was not used, and the coloring with time was evaluated. The results are shown in Table 3.

Comparative Example 15 A sheet-like substance was prepared in the same manner as in Example 20 except that the radical scavenger was not used, and the coloring with time was evaluated. The results are shown in Table 3.

[0042]

[Table 3]

[0043]

As is apparent from the above examples, the composition of the present invention has good water resistance even when dried or heat-treated at a relatively low temperature and left for a long time under high temperature and high humidity. When it is done, the coloring stability is very excellent.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C08L 5/08 LAX 7415-4J C09D 129/04 PFM 6904-4J PFN 6904-4J C09J 129/04 JCT 6904-4J JCU 6904-4J // (C08L 29/04 5:08) (72) Inventor Hitoshi Maruyama 1621 Sakata, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd.

Claims (1)

[Claims] 1. (A) Polyvinyl alcohol-based resin 10
0 parts by weight, 1 to 90 parts by weight of (B) 1% by weight aqueous solution having a viscosity of 70 centipoise or less at 20 ° C., 1 to 20 parts by weight of (C) aldehyde compound, and (D)
A water resistant composition comprising 0.0001 to 10 parts by weight of a reducing agent and 0.0001 to 10 parts by weight of a radical scavenger (E).