JPS6099104A - Crosslinkable group-containing modified polyvinyl alcohol and its preparation - Google Patents

Abstract

PURPOSE:To obtain the titled modified PVA providing a molded article having extremely improved water resistance only by heating the molded article, by reacting a vinyl alcohol polymer with a specific compound in the presence of a basic catalyst so that the polymer is modified. CONSTITUTION:In the presence of a basic catalyst, hydroxyl group of a vinyl alcohol polymer having preferably 200-3,500 polymerization degreen and 70- 100mol% sapanification degree is reacted with a compound (e.g., N-methylolmethacrylamide, etc.) shown by the formula I (R<1> is H, or CH3; R<2> is H, or 1-4C alkyl) so that Michael addition is carried out, to give the desired modified PVA having 0.1-30mol% unit shown by the formula II, 99.7-70mol% unit shown by the formula III, and 50-10,000 polymerization degree. USE:A food packaging film, membrane having no permeability to gas, adhesive of crosslinking type, etc.

Description

[Detailed description of the invention] The present invention relates to modified polyvinyl alcohol.

More specifically, the present invention relates to a method for producing a self-crosslinking modified polyvinyl alcohol containing copolymerized units of the following formulas (1) and (n) as essential components and having a degree of polymerization of 50 to too much.

Conventionally, vinyl alcohol-based polymers have high tear strength, toughness,
Because of its excellent transparency, gas barrier properties, oil resistance, and adhesive properties, it can be used for molded products such as films and sheets.
- Widely used as adhesives, etc. However, vinyl alcohol-based polymers inherently have the disadvantage of poor water resistance, so they have traditionally been used in fields where water resistance is required.
Formalization, benzalization, cyinone anate crosslinking,
Water resistance is imparted through post-treatments such as dialdehyde cross-linking, but these often involve chemical treatment after molding, which causes problems in recovery of treatment agents, disposal of waste liquids, and other handling issues. There are many things.

The present inventors have been conducting various studies on making vinyl alcohol polymers water resistant, and as disclosed in JP-A-51-102091, self-crosslinking properties in which acrylic acid esters are reacted with vinyl alcohol polymers have been proposed. We are getting resin. However, this reaction has the drawbacks of low yield and easy side reactions. Therefore, after further investigation, we found that instead of acrylic esters, we used the general formula CH2=CR1C.
0NHCH20R2 (however, R1 is hydrogen or methyl group,
A resin modified by Michael addition of a compound (R2 is hydrogen or an alkyl group having 1 to 4 carbon atoms) to a vinyl alcohol polymer in the presence of a base catalyst can be produced by a simple addition during or after molding. It was discovered that heat treatment significantly improves water resistance, leading to the completion of the present invention.

Conventionally, hydroxy group-containing polymer, CCHz: 2C1fCON
Regarding the reaction of l-ICH20H, see ■ Koka 68.1762 (1965), ■ L6F;, 176
6 (1965), ■Tokuko Showa 49-5923, ■Tokuko Showa 5
7-48007 and the like are known, but these all involve dehydration between the aqueous group of the hydroxyl group-containing polymer and the methylol group of N-methylolacrylamide using an acid medium. A reaction is performed to obtain the desired product.

However, the following formula (1) is still available in Japanese Patent Application Laid-open No. 58-76403.
C0NHZOR2 containing the copolymerization component of
fcki2- CH-)-OH modified polyvinyl alcohol is disclosed. This modified polyvinyl alcohol is composed of vinyl acetate and CH2=CRIC.
ONHCH20R2 (However, R1 and R2 are the same as above)
The desired product is obtained by copolymerizing monomers containing the above and saponifying the copolymer. Although the above-mentioned modified polyvinyl alcohol has a crosslinking group in its molecule, an acid catalyst is essential when carrying out the crosslinking reaction. , (1) to 0.1
~30 molar ratio, (It) f.

Contains 99.9 to 70 mol, and the degree of polymerization is 50 to 1 ooo.

It is a self-crosslinking modified polyvinyl alcohol.

(() (-CR2-CH+ Hair α: H2CHR"C0NHC1-bOR2 (However, R1
, R2 are the same as above) (II') (-CH2-CH2-)-OH In addition to containing the above-mentioned copolymerized units (1) and (n) as essential components, a small amount of other copolymerized units (e.g. , a vinyl ester unit represented by vinyl acetate, an olefin unit represented by ethylene, an alkyl vinyl unit represented by methyl vinyl ether, etc.).

Modified polyvinyl alcohol containing such a structure is
When carrying out the crosslinking reaction, no particular acid catalyst is required, and a simple heat treatment can be sufficient.

Furthermore, the modified polyvinyl alcohol of the present invention can be obtained by treating a vinyl alcohol polymer with the general formula C using a base catalyst.
H2=CH”C0N1(CHzOR2(However, ■71.
R2 is the same as above) can be obtained by Michael addition. The reaction format is ~eH2- as shown in the following formula.
0H-CH2-OH-+ CH22CRICONJ'(
CH20R20HOH (However, R1 and R2 are the same as above) Catalyst =CH2-CH-CH2-C1f -OH0CH
2C) IR”C0NHCH20 also 2(Idanshi, R1,
R2 is the same as above) Proceed. Since the modified polyvinyl alcohol of the present invention is soluble in polyvinyl alcohol solvents such as water, dimethylformamide (DMF), and dimethyl sulfoxide (L)MSO), it can be formed into a solution, formed into a film, or formed into other shapes by appropriate means. After coating or coating on a substrate, these molded products can be simply heat-treated.
The crosslinking reaction progresses and water resistance is significantly improved.

The self-crosslinking resin according to the present invention has a high resistance to (
It not only significantly improves water properties (heat), but also improves overall moldability, making it suitable for food packaging films, gas-impermeable membranes, cross-linked adhesives, fiber processing agents, paper processing agents, tank linings, hoses, It can be used in a wide range of applications, including protective films for beverage containers, molded products, binders for glass fibers, ceramics, and gypsum boards, binders for nonwoven fabrics, and glass interlayer films.

Vinyl alcohol polymers used in the present invention include polyvinyl alcohols having various degrees of polymerization and saponification, vinyl esters such as vinyl acetate, and small amounts of other polymerizable monomers (e.g. , α-olefins such as ethylene, propylene, and imbutylene, alkyl vinyl ethers such as methyl vinyl ether,
It includes not only saponified copolymers with one or more types of vinyl chloride, but also modified polyvinyl alcohols such as cyanethylated polyvinyl alcohol.

Regarding the degree of polymerization of vinyl alcohol polymer: 1d50~
10000 can be used, but preferably 100~
5000, preferably 2000 to 3500.

There are no particular restrictions on the degree of saponification, but in order to maintain the properties of polyvinyl alcohol, the degree of saponification is between 70 mol% and 1% by mole.
00 mole fission is better.

On the other hand, as a modifier for the above-mentioned vinyl alcohol polymer, the general formula CH22CR''C0NHCH20R
If the number of alkyl carbon atoms in R2 of the compound represented by 2 (wherein R1 and 12 are the same as above) exceeds 5, the crosslinkability by heat treatment will decrease, so the number of alkyl carbon atoms is preferably 4 or less. As such, for example, N-methylol acrylamide, N-methylol methacrylamide,
N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-ethoxymethyl(meth)acrylamide, N-n-propoxymethylacrylamide 1N-isopropoquinemethylacrylamide, N-n
-butoxymethylacrylamide, N-butoxymethylacrylamide, and the like. Of these,
In terms of reactivity and the like, N-methylol(meth)acrylamide and N-methoxymenal(meth)acrylamide are particularly preferred.

The above-mentioned reaction between the vinyl alcohol polymer and N-methylol or N-alkoxy(meth)acrylamide is carried out in the presence of a base catalyst, and the base catalysts used at this time include sodium hydroxide, potassium hydroxide, Alkali metal hydroxides such as lithium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, barium hydroxide, alkali metal alkoxides such as sodium methoxide, potassium methoxide, sodium butoxide, potassium butoxide, etc. preferable.

In addition, tertiary amines such as triethylamine, basic salts such as sodium acetate, etc. can also be used.
A 1 to 35 K (fit% 9 solution is prepared in a solvent such as N-methyl-2-pyrrolidone or DMF (a mixed solvent may also be used), and the amount is usually 0.5 to 15 molar relative to the hydroxyl group of the vinyl alcohol polymer. base, 5 to 300 mol -〇〇)1
2=cR"cONHcH20R"(R'.

R2 is the same as above), and a small amount of a polymerization inhibitor such as hydroquinone or hydroquino/monomethyl ether is added, and the reaction is carried out at a temperature of 15°C to 75'C for 5 minutes to 10 hours, and excess methanol, ethanol, n- Add the reaction VD to a solvent such as propatool, inglobanol, or acetone (mixed solvents are also acceptable), or add phosphoric acid (including various types), acetic acid, hydrochloric acid, sulfuric acid, nitric acid, etc. to the reaction mixture. It is also possible to neutralize by adding an acid (aqueous solutions of various concentrations may be used) and take out the reactant. In addition, in the above-mentioned Michael type addition reaction, depending on the combination of reaction mixtures, polymer concentrations, catalyst concentrations, reactant charging ratios, reaction temperatures, and reaction times other than those listed above may be selected. , or a vinyl alcohol polymer is swollen with a solvent and a catalyst as described above, for example, in an inert solvent such as benzene, toluene, hexane, or cyclobexane.
There is no problem in reacting with CH20R2 (R1 and R2 are the same as above) in a heterogeneous system.

CH2= in the production of modified vinyl alcohol of the present invention
CH"C0NHCH20R2(R", "2ha above":
The amount of reaction L) can be increased or decreased as desired by appropriate selection of reaction conditions, but is preferably 1 to 30 mol per mol, preferably 0 to 30 mol per hydroxyl group of the vinyl alcohol-based pure polymer. .5 to 15 mol, particularly preferably 1 to 12 mol.

If the amount deviates from these ranges, for example, if the amount is less than 0.1 mol%, the water resistance may be insufficient even if it is a heat-treated molded product, and if it exceeds 30 mol%, the water resistance may deteriorate during reaction or molding. In some cases, gelation may occur, which may cause problems in reaction handling or molding operations.

The modified polyvinyl alcohol of the present invention has a reactive hydroxyl group in the molecule.
2 (R”, R2f4 same as above),
It is thought that simply heating after film formation, coating, and molding generates intermolecular crosslinks and significantly improves (hot) water resistance.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited in any way by the following Examples.

Example 1 10f of polyvinyl alcohol (degree of polymerization: 1700, saponification: 99.5 mol%) in a 200 tLl triangular flask
After dissolving 902 ml of deionized water, 8 me of 10 ml of iced sodium hydroxide solution, 15.02 ml of N-methylolacrylamide, and 0.015 F of hydroquinone monomethyl ether were all added and reacted at 65°C for 3 hours.

After the reaction, the reaction mixture is poured into excess methanol, the precipitate is separated, and the precipitate is thoroughly washed with methanol to remove the catalyst.
Unreacted substances were removed and the mixture was dried in a vacuum dryer at 50°C until a constant weight was obtained. The weight of the dry product was 11.6 f. By IR and NMR analysis of this dried product, it was found that N-methylolacrylamide was added to 7.8 moles of polyvinyl alcohol hydroxyl group in a Michael type manner.

Example 2.

10? Polyvinyl alcohol (7R degree 1500, saponification degree 98.5 molar), 25. The reaction was carried out at 60° C. for 6 hours in the same manner as in Example 1 except that 0.05 r of N-methoxymethylacrylamide and 0.05 r of no-hydroquinone monomethyl ether were added, and the reaction product was taken out and dried. The weight of the dry product was 12.37, and IR and NMR analysis revealed that 11.3 mol% of KN-methquine methylacrylamide was added to the hydroxyl groups of polyvinyl alcohol in a Michael type.

Example 3 15? After dissolving t-85'' of polyvinyl alcohol (degree of polymerization 500, degree of saponification 99.5 mol%) in deionized water,
15ml of 10T potassium hydroxide aqueous solution, 8.02N
-Methylolmethacrylamide and 0.02f of 7-hydroquinone 7-methyl ether were added, and after reaction at 70°C for 1 hour, the reaction product was taken out and dried in the same manner as in Example 1. Its weight was 15.3 r, and its IR and NMR analysis revealed that 1 of the hydroxyl groups of polyvinyl alcohol
．． Michael-type addition of N-methylolmethacrylamide was observed at 9 mol.

Example 4 5V of ethylene-vinyl alcohol copolymer (ethylene content: 7.4 moles, saponification: 99.5 moles, degree of polymerization: 1500) was dissolved in 952% water, and 7% of 10% hydroxylated. Add sodium, 0.005 f of hydroquinone monomethyl ether, and 10.62 f of N-n-phytoxymethylacrylamide, and react at 50°C for 4 hours.
After cooling, an equivalent amount of acetic acid was added to neutralize the mixture, and the mixture was poured into excess acetone, followed by the same procedure as in Example 1, and the reaction mixture was taken out and dried. Its weight is 5.2f and its IR and NM
According to R analysis, 1.2 mol % of KN-n-butoxymethylacrylamide was added to the hydroxyl groups of the ethylene vinyl alcohol copolymer in a Michael type manner.

Example 5 The products obtained in Examples 1 to 4 were all soluble in 85°C hot water. Therefore, an aqueous solution of these products was prepared and cast onto a glass plate to form a 10 μm thick film. For comparison, polyvinyl alcohol (
A film with a degree of polymerization of 1700 and saponification [99.5 mol%] was produced. Take some of these films and heat them to 150℃
It was found that the modified vinyl alcohol polymer according to the present invention has self-crosslinking properties in which intermolecular crosslinking occurs simply by heating for 10 minutes or more. The samples (before rA treatment and after heat treatment) were almost insoluble in various organic solvents such as benzene and acetone, and had good solvent resistance.

Patent applicant RiRashi Co., Ltd. Representative Patent Attorney Ken Honda

Claims (3)

[Claims] (1) The copolymerized units of the following formulas (1) and ([I) are essential components, and (1) t-o. 1 to 30 molti, (■) 9
A self-crosslinkable modified polyvinyl alcohol containing 9.9 to 70 mol. (-CH2-CH-) OCR2C) LRICONHCH20R2 (However, R1
is hydrogen or methyl group, R2 [hydrogen or alkyl group having 1 to 4 carbon atoms] (I) +CH2-CH-) OH (n) (2) As a copolymerization unit, (1) is +CH+ -CH-) OCR2CHR"C0NHCHzOH (however, R1 is hydrogen or a methyl group), and (II) is +CH2-CH+, as described in claim 1 Modified polyvinyl alcohol 0 (3) To the hydroxyl group of the vinyl alcohol polymer, in the presence of a base catalyst, the general formula CH2=CR'C0NHCH2
1. A method for producing modified polyvinyl alcohol, which comprises reacting a compound represented by 0R2 (where B2 represents hydrogen or a methyl group and B2 represents hydrogen or an alkyl group having 1 to 4 carbon atoms).