JPH0131764B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a novel vinyl alcohol copolymer having a crosslinkable group. Polyvinyl alcohol (hereinafter abbreviated as PVA) has long been known as a typical water-soluble polymer, and is used as a raw material for synthetic fibers such as vinylon or film, and for a wide range of industrial applications such as adhesives, binders, coatings, and emulsifiers. has been used.
In these applications, it is often necessary to improve water resistance, and many methods for improving water resistance have been proposed. Regarding the technology related to water resistance and insolubilization, see "Povaal" by Nagano, Yamane, and Toyoshima (revised new edition), Kobunshi Publishing Association (1981)
Reviewed on pages 256-261. formalin,
Acetaldehyde and the like are used to make vinylon waterproof, but they have not been put to practical use in other glue or emulsifier applications due to problems such as odor. Dialdehyde compounds such as glyoxal and glutaraldehyde, or polyvalent aldehyde compounds such as dialdehyde starch are known as water-resistant agents for PVA, but the amount used must be limited in order to create a film that can withstand boiling water. It has the disadvantage that it needs to be made high and is easily colored during heat treatment. N-methylol urea and N-methylol melamine also have water resistance, but have the disadvantage of emitting formalin. Also,
Compounds containing inorganic elements such as boron, titanium, zircon, chromium, and silicon also have crosslinking properties and are used for water resistance, but in many cases these compounds are
When added to a PVA aqueous solution, thickening or gelation occurs, or the viscosity of the liquid becomes unstable, so sufficient care must be taken in practical use, and there are few examples of industrial use. In contrast to water resistance using the above additives,
There are also a few proposals known to modify PVA itself to make it water resistant. The saponified copolymer of arylidene diacetate and vinyl acetate is a modified PVA with aldehyde in the side chain, and is easily crosslinked by acid treatment. However, if the amount of modification is increased in order to provide sufficient water resistance, cross-linked insoluble matter tends to occur during the production of PVA, and it tends to be easily colored, so it has not yet been put to practical use. Thus, it has been more difficult than expected to industrially and effectively impart water resistance or crosslinking properties to PVA, and a sufficiently effective method has not yet been known. Based on this situation, the inventors of the present invention
As a result of our research, we aimed to establish a method to industrially produce PVA at low cost by introducing a crosslinkable group that gives PVA itself water resistance, and which has excellent solubility in solvents such as water before crosslinking. The present invention has been completed, and the vinyl alcohol copolymer shown in the present invention is a novel compound previously unknown. That is, an object of the present invention is to clarify a method for producing a useful modified PVA copolymer containing a vinyl alcohol unit and a crosslinkable group. The copolymer of the present invention has the formula CH ₂ =CH-OCOR ³
(R ³ means a hydrogen atom or a lower alkyl group), particularly preferably vinyl acetate and the formula CH ₂ =CR ¹ —CONHCH ₂ O—
An alkoxymethyl group-containing polymerizable monomer represented by R ² (R ¹ is a hydrogen atom or a lower alkyl group, R ² is an alkyl group), especially N-alkoxymethyl in which R ² is an alkyl group having 1 to 4 carbon atoms. (Meth)acrylamide, particularly preferably N-methoxymethylacrylamide or N-n-butoxymethylacrylamide, is copolymerized using a radical polymerization initiator, and then an alkaline catalyst is applied to an alcoholic solution of this copolymer. It is produced by converting the vinyl ester units in the copolymer into vinyl alcohol units that are partially or highly saponified. The vinyl ester that can be used in producing the copolymer of the present invention is any vinyl ester that becomes vinyl alcohol when saponified after copolymerization, and has essentially the same effect, but usually vinyl acetate, Examples include vinyl formate and vinyl propionate, with vinyl acetate being more preferred from an economic standpoint. Furthermore, as the polymerizable monomer having a crosslinkable group used in the present invention, CH ₂ =CR ¹ -CONHCH ₂ O-
It is a compound represented by R ² (R ¹ is a hydrogen atom or a lower alkyl group, and R ² is an alkyl group). R ¹ is usually preferably a hydrogen atom or a methyl group. As the alkyl group R ² , an alkyl group having any chain length may be used in terms of imparting crosslinking properties, but an alkyl group having 1 to 4 carbon atoms is usually preferred. Specific examples include N-methoxymethylacrylamide, N-methoxymethylmethacrylamide, N-
Ethoxymethylacrylamide, N-ethoxymethylmethacrylamide, Nn-propoxymethylacrylamide, Nn-propoxymethylmethacrylamide, N-isopropoxymethylacrylamide, N-isopropoxymethylmethacrylamide, Nn-butoxymethylacrylamide , N-n-butoxymethylmethacrylamide,
N-isobutoxymethylacrylamide, N-isobutoxymethylmethacrylamide, N-tert-
butoxymethylacrylamide, N-tert-butoxymethylmethacrylamide, among which N-methoxymethylacrylamide or N-tert-butoxymethylmethacrylamide.
-n-butoxymethylacrylamide is particularly preferred in terms of effectiveness and economy. These monomers have been well known for a long time, for example as described in British patent 955420.
In this issue, a copolymer with vinyl acetate and acrylic acid ester is shown. However, saponified copolymers produced by saponifying copolymers of N-alkoxymethyl (meth)acrylamide and vinyl ester are not known, and industrially It is completely unknown that copolymers with significant superior performance can be obtained. Copolymerization of the above-mentioned N-alkoxymethyl (meth)acrylamide monomer and vinyl ester can be carried out using any polymerization method such as bulk polymerization, solution polymerization, suspension polymerization, or emulsion polymerization, but the present invention Solution polymerization is usually preferred for many purposes. As the solvent used in solution polymerization, lower alcohols, particularly methanol, are industrially suitable. Bulk polymerization and solution polymerization can be carried out either batchwise or continuously, while suspension polymerization and emulsion polymerization are usually carried out batchwise. In the case of a batch method, it is well known that the monomer composition changes with the polymerization rate according to the comonomer reactivity ratio (r ₁ , r ₂ ), but when the monomer composition is constant, In order to obtain a copolymer having a uniform copolymer composition, it is desirable to adopt a so-called semi-batch method in which one or both monomers are added so that the following is achieved. One way to calculate the amount added in this case is to use RJHanna
and Engineering Chemistry, Vol.49, No.2208―
209 (1957). In the case of continuous multi-column copolymerization, for the same reason, it is desirable to add monomers to the second and subsequent columns so that the monomer composition in each column is constant. As a polymerization initiator, 2,2'-azobisisobutyronitrile,
1,1'-azobis-(cyclohexane-1-carbonitrile), 2,2'-azobis-isobutyronitrile, 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'- Azobis-(4-methoxy-2,4-dimethylvaleronitrile), 2,
Known radical polymerization initiators such as 2'-azobis-(2-amidinopropane) dihydrochloride, benzoyl peroxide, potassium persulfate, ammonium persulfate, t-butyl hydroperoxide, di-t-butylcumene hydroperoxide peroxide, etc. may be used.
Further, a degree of polymerization regulator such as acetaldehyde or alkyl mercaptan can also be added to the polymerization system. The polymerization reaction temperature is usually selected from the range of 50°C to the boiling point. The reaction rate of the monomers is appropriately determined depending on the purpose, such as economical efficiency and adjustment of the degree of polymerization. The amount of N-alkoxymethyl group-containing monomer units in the copolymer is appropriately selected depending on the application and is not particularly limited, and a copolymer with any composition can be synthesized.
When the purpose is crosslinking, it is preferable to select from the range of 0.05 to 10 mol%. Further, in the case of solution polymerization, the degree of polymerization of the copolymer can be adjusted by adjusting the amount of the solvent, especially methanol, and the amount of the degree of polymerization regulator such as aldehydes. There is no restriction on the degree of polymerization, and copolymers with a wide range of degrees of polymerization can be synthesized, but the degree of polymerization of the saponified product described later is usually selected from the range of 200 to 3,600. After the copolymerization is completed, if vinyl ester remains in the reaction solution, it is necessary to separate and remove it by distillation or the like. When the N-alkoxymethyl group-containing monomer remains, it may be removed, or it may often be allowed to remain without any problem. In addition to vinyl ester and N-alkoxymethylacrylamide, other unsaturated monomers copolymerizable with these monomers such as ethylene, propylene,
-α-olefins such as hexene and 2-octene;
Unsaturated acids such as (meth)acrylic acid, crotonic acid, (anhydrous) maleic acid, fumaric acid, and itaconic acid, or their alkyl esters or alkali salts thereof; Unsaturated amides such as (meth)acrylamide and N-methylolacrylamide; 2 -Acrylamide-Sulfonic group-containing monomer such as 2-methylpropanesulfonic acid or its salt; N-(2-dimethylaminoethyl)acrylamide, N-(3
-dimethylaminopropyl) methacrylamide,
Cationic group-containing monomers such as N-(1,1-dimethyl-3-dimethylaminopropylacrylamide) or quaternary compounds thereof; alkyl vinyl ethers; styrene; N-vinylimidazole, N-vinyl-2-methylimidazole or Unsaturated imidazole compounds such as quaternary compounds; N-vinylacetamide, N-vinyl-N-
Methyl-acetamide, N-vinyl-N-methylformamide, methyl-N-vinyl carbamate, ethyl-N-vinyl carbamate, tert-butyl-N-vinyl carbamate, methyl-N-isopropyl carbamate, ethyl-N-isopropenyl carbamate, Polymerization is performed in the coexistence of N-vinyl or N-isopropenyl compounds such as tert-butyl-N-isopropenyl carbamate, and these monomer units are present at 10 mol% in the copolymer.
It can also be manufactured so that it is present at a level below. The vinyl ester portion of the copolymer thus obtained is then saponified. It is usually advantageous to carry out the saponification reaction as a solution of the copolymer in alcohol, especially methanol. Not only anhydrous alcohols but also those containing a small amount of water can be used depending on the purpose, and organic solvents such as methyl acetate and ethyl acetate may be optionally contained. As the saponification catalyst, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alcoholates such as sodium methylate and potassium methylate, alkaline catalysts such as ammonia, or acidic catalysts such as hydrochloric acid and sulfuric acid can be used. . In the process of studying the present invention, it became clear that when acidic catalysts are used, they tend to be cross-linked and become unnecessary when drying the saponification reaction product.For this reason, industrially, alkaline catalysts, especially from the economic point of view, are Sodium oxide is most suitable for the purposes of this invention. The saponification temperature is usually selected from the range of 10 to 50°C. It is undesirable to leave the product under strong alkaline or acidic conditions at a high temperature of 100°C or higher for a long time, as the bond between the amide group or alkoxymethyl group will gradually decompose, but it is usually not necessary to leave it under such conditions. During saponification, the amide bond or alkoxymethyl group remains stable without being substantially decomposed. Through the saponification reaction, vinyl ester units are partially or highly saponified and converted into vinyl alcohol units, but this conversion rate can be set to any value depending on the intended use of the vinyl alcohol copolymer of the present invention. However, for general purposes, it is preferable that the copolymer contains 99.95 to 70 mol% of vinyl alcohol units and 0 to 29 mol% of vinyl ester units. Further, the content of the N-alkoxymethyl group monomer unit is usually preferably in the range of 0.05 to 10 mol%, as described above. As the chain length of the alkyl group of the N-alkoxymethyl group-containing monomer used increases, the water solubility of the copolymer formed increases when the content of this monomer unit increases and/or when the content of vinyl ester units increases. If modified PVA is intended as a water-soluble copolymer, it is necessary to adjust the type and content of the N-alkoxymethyl group-containing monomer and the content of vinyl ester units. It is industrially preferable to use a method in which a white gel or precipitate is produced by the progress of the saponification reaction in the same way as in the case of ordinary PVA, and by crushing, washing, and drying this as necessary, vinyl alcohol can be produced. system copolymer powder can be obtained. Drying at 100℃ does not affect the solubility of the PVA as long as it is carried out for the purpose of evaporating the solvent.
If left at higher temperatures for a long time, care must be taken as partial crosslinking and insolubilization will occur, but normally there is no need to leave it under such conditions. In many cases, the vinyl alcohol copolymer of the present invention can be stored and transported in powder form like general PVA, and many copolymers whose composition has been adjusted to be water-soluble are After dispersing in water, a uniform paste solution can be obtained by heating while stirring. When the content of N-alkoxymethyl group-containing monomer units is high and/or when the content of vinyl ester units is high and water solubility is low, mixing alcohols such as methanol, ethanol, propanol, butanol, etc. with water. A solvent or dimethyl sulfoxide can also be used as a solvent. In many cases, the vinyl alcohol copolymer produced by the present invention looks similar to ordinary unmodified PVA, but by curing it under appropriate conditions, it can be formed into a film that can withstand boiling water. It can be easily distinguished from other PVA by its distinctive properties of imparting strength. Curing conditions include denatured PVA solution, especially sulfuric acid in an aqueous solution.
Using catalytic amounts of mineral acids such as hydrochloric acid, nitric acid, and phosphoric acid, organic acids such as acetic acid, oxalic acid, citric acid, and tartaric acid, and acid salts such as aluminum sulfate, ammonium nitrate, ammonium sulfate, and ammonium chloride,
Also, a method of heating and drying is mentioned. The degree of crosslinking and water resistance may vary depending on the purpose, and can be adjusted by selecting the amount of catalyst, heating temperature, and heating time. In this way, the novel vinyl alcohol copolymer obtained in the present invention can be used in various ways, taking advantage of its crosslinked water resistance function in addition to the performance of PVA. For example, sizing agents for textiles, textile processing agents, surface sizing agents for paper, binders for pigment coating, internal additives for papermaking, improvers for amino resin adhesives, emulsion stabilizers for emulsion polymerization, wall materials for microcapsules. , gypsum board, glass fiber, rock wool, ceramic binder, photosensitive resin, stabilizer for suspension polymerization, film,
Molded products such as sheets, pipes, tubes, fibers, etc.
Adhesives for wood, paper, aluminum foil, plastic, etc.
The present invention has a wide range of applications, including binders for nonwoven fabrics, additives for cement and mortar, and selective separation membranes, and the present invention has great industrial significance. Hereinafter, the present invention will be specifically explained with reference to Examples. In the following, parts or % mean parts by weight or % by weight unless otherwise specified. Example 1 5000 ml of vinyl acetate was placed in a heated reaction tank equipped with a stirrer, a thermometer, a chemical feed pump, and a reflux condenser.
1,260 parts of methanol, 60 parts of N-methoxymethylacrylamide, and 2 parts of 2,2'-azobisisobutyronitrile were charged, and the internal temperature was raised to 62°C to start polymerization. During a polymerization time of 90 minutes, 150 parts of N-methoxymethylacrylamide was dropped into the polymerization system from a chemical feed pump depending on the solid content concentration of the polymerization system. The solid content concentration in the system at the time of termination of polymerization was 21.0%. This polymerization liquid was charged into a distillation column, and methanol vapor was introduced from the bottom of the column to distill off unreacted vinyl acetate monomer, yielding a 33% methanol solution of the copolymer. It was confirmed by nuclear magnetic resonance analysis that this copolymer contained 8.8 mol% of N-methoxymethylacrylamide units and 91.2 mol% of vinyl acetate units. 2970 parts of a methanol solution of this copolymer was heated at 40°C.
While stirring, 115 parts of 1N caustic soda methanol solution was added thereto, and after thorough mixing, the mixture was allowed to stand.
The whole gelatinized after 10 minutes and 10 seconds. After a further 20 minutes, the gel was ground using a grinder, washed with methanol, and dried to obtain a white polymer powder. This copolymer had excellent solubility in water. This copolymer was sufficiently washed with methanol, and the aqueous solution was purified by reprecipitation in acetone, and the proton nuclear magnetic resonance spectrum of the heavy aqueous solution is shown in FIG. 3.34ppm,
The absorption at 4.63ppm and 2.5-2.8ppm is attributed to the methoxy group of the N-methoxymethylacrylamide unit in the copolymer, the methylene group sandwiched between N and O, and the methine group proton, and from the absorption intensity, N- It was analyzed to contain 8.8 mol% of methoxymethylacrylamide units. In addition, the absorption at 2.1ppm is attributed to the methyl group proton of the vinyl acetate unit that remains unsaponified, the absorption at 4ppm is attributed to the methine group proton in the main chain of the vinyl alcohol unit, and the absorption at 1.7ppm is attributed to the methylene group proton in the main chain. From the absorption intensity, it was confirmed that vinyl acetate units and vinyl alcohol units contained 2.8 mol% and 88.4 mol%, respectively. That is, the obtained copolymer is a copolymer of N-methoxymethylacrylamide, vinyl alcohol, and vinyl acetate, and the composition ratios thereof are 8.8 mol%, 88.4 mol%, and 2.8 mol%, respectively. Further, the degree of polymerization determined by gel vermulation gas chromatography was 2200. Example 2 In the same manner as in Example 1, 10,000 parts of vinyl acetate, 2,508 parts of methanol, 32 parts of N-methoxymethylacrylamide and 14 parts of 2,2'-azobisisobutyronitrile were charged to start polymerization. 236 parts of N-methoxymethylacrylamide was added and 110 minutes later, a polymerization solution with a solid content of 50.6% was obtained. After distilling off the vinyl acetate monomer, 440 parts of a 0.15N caustic soda methanol solution was added to 1180 parts of a 41.2% copolymer methanol solution to carry out a saponification reaction. The obtained copolymer had excellent water solubility, consisted of 2.9 mol% of N-methoxymethylacrylamide units, 95.7 mol% of vinyl alcohol units, and 1.4 mol% of vinyl acetate units, and had a degree of polymerization of 1950. Example 3 To 728 parts of a methanol solution of the N-n-methoxymethylacrylamide-vinyl acetate copolymer obtained by copolymerization in Example 2, 150 parts of methyl acetate and
Saponification was carried out by adding 122 parts of 0.1N caustic soda methanol solution. The obtained copolymer has excellent water solubility and contains 2.9 N-methoxymethylacrylamide units.
mol%, vinyl alcohol units 83.7 mol% and vinyl acetate units 13.4 mol%, degree of polymerization 1950
It was a copolymer of Example 4 In the same manner as in Example 1, 11,040 parts of vinyl acetate, 960 parts of methanol, 11 parts of N-methoxymethylacrylamide and 3.2 parts of 2,2'-azobisisobutyronitrile were charged and polymerization was started. N-
27 parts of methoxymethylacrylamide was added and 75 minutes later, a polymerization solution with a solid content of 18.4% was obtained. After distilling off the vinyl acetate monomer, add 12 parts of 1N caustic soda methanol solution to 297 parts of 33% copolymer methanol solution.
A saponification reaction was carried out. The obtained copolymer has excellent water solubility and contains 0.9 mol% of N-methoxymethylacrylamide units and vinyl alcohol units.
Consisting of 98.5 mol% and 0.6 mol% of vinyl acetate units,
It was a copolymer with a degree of polymerization of 3540. Example 5 Vinyl acetate was added to the same reaction vessel used in Example 1.
5,000 parts of methanol, 1,270 parts of methanol, 80 parts of N-n-butoxymethylacrylamide, and 3.5 parts of 2,2'-azobisisobutyronitrile were charged, and the internal temperature was set at 61°C, and polymerization was started. During the polymerization time of 60 minutes, N-n
-190 parts of butoxymethylacrylamide was dropped into the polymerization system from a chemical feed pump depending on the solid content concentration of the polymerization system. The solid content concentration in the system when polymerization is stopped is
It was 20.0%. In the same manner as in Example 1, unreacted vinyl acetate monomer was distilled off to obtain a 33% methanol solution of the copolymer. It was confirmed by nuclear magnetic resonance analysis that this copolymer contained 8.4 mol% of Nn-butoxymethylacrylamide units and 91.6 mol% of vinyl acetate units.
While stirring 2790 parts of this copolymer solution at 40°C, 109 parts of 1N caustic soda methanol solution was added thereto, and after thorough mixing, the mixture was allowed to stand. After 10 minutes and 20 seconds, the entire system turned into a gel. After a further 20 minutes, the gel was ground using a grinder, washed with methanol, and dried to obtain a white polymer powder. This copolymer did not dissolve in water but completely dissolved in dimethyl sulfoxide. After purifying this copolymer, its dimethyl sulfoxide- _d6
Proton nuclear magnetic resonance spectra were measured in solution. The results are shown in Figure 2. 0.85ppm and
The absorption at 3.2 ppm is assigned to the protons of the methyl group in the n-butoxy group in the N-n-butoxymethylacrylamide unit and the methylene group adjacent to the O atom, respectively, and the absorption at 1.4 ppm, 3.8 ppm and
The absorption at 4.1-4.7 ppm is attributed to the methylene group in the main chain, the methylene group in the butoxy group (excluding the methylene group adjacent to the O atom), the methine group in the vinyl alcohol unit, and the hydroxyl group in the vinyl alcohol unit. The vinyl acetate units are substantially mostly saponified. In other words, the obtained copolymer is substantially a copolymer of N-n-butoxymethylacrylamide and vinyl alcohol, and its composition ratio is 8.4 mol% and 91.6 mol% from the absorption intensity ratio of the nuclear magnetic resonance spectrum. . Furthermore, the degree of polymerization determined by gel permeation gas chromatography is 2250. Example 6 Vinyl acetate was added to the same reaction vessel used in Example 1.
5,000 parts of methanol, 1,255 parts of methanol, 20 parts of N-n-butoxymethylacrylamide, and 7 parts of azobisisobutyronitrile were charged, and the internal temperature was set at 60° C. to initiate polymerization. During the polymerization time of 120 minutes, 160 parts of N-n-butoxymethylacrylamide was dropped into the polymerization system from a chemical feed pump according to the solid content concentration of the polymerization system. When the polymerization was stopped, the solid content concentration in the system was 51.4%. It was hot. In the same manner as in Example 1, unreacted vinyl acetate monomer was distilled off to obtain a 38% methanol solution of the copolymer. It was confirmed by nuclear magnetic resonance analysis that this copolymer contained 2.7 mol% of Nn-butoxymethylacrylamide units and 97.3 mol% of vinyl acetate units. While stirring 3,080 parts of this copolymer solution at 40° C., 1,262 parts of a 0.1N caustic soda methanol solution was added thereto, mixed well, and then allowed to stand. The entire system gelled after 7 minutes and 15 seconds. 20 more
After a few minutes, the gel was pulverized using a pulverizer, washed with methanol, and dried to obtain a white polymer powder. The obtained copolymer had excellent solubility in water. After purifying this copolymer, the proton nuclear magnetic resonance spectrum of its heavy aqueous solution was measured. The spectrum is shown in Figure 3. The absorption consisting of three lines at 0.85-1.0ppm is due to the methyl group proton in the N-n-butoxymethylacrylamide unit, and the absorption at 3.6ppm is due to N.
-n in n-butoxymethylacrylamide unit
- Attributed to the methylene group proton adjacent to the O atom in the butoxy group, and also 1.7ppm, 2.15ppm
The absorptions of 4.1 ppm and 4.1 ppm were assigned to methylene groups (other than the methylene groups in the main chain and butoxy groups), methyl groups in vinyl acetate units, and methine group protons in vinyl alcohol units, respectively. In other words, the obtained copolymer is a copolymer of N-n-butoxymethylacrylamide, vinyl alcohol, and vinyl acetate, and its composition ratio is 2.7 mol% based on the absorption intensity ratio of the nuclear magnetic resonance spectrum.
95.2 mol% and 2.1 mol%. The degree of polymerization determined by gel permeation gas chromatography is 1880. Example 7 In the same manner as in Example 6, 14,000 parts of vinyl acetate, 3,505 parts of methanol, 20 parts of N-n-butoxymethylacrylamide and 20 parts of 2,2'-azobisisobutyronitrile were charged to start polymerization. Inside N
150 parts of -n-butoxymethylacrylamide was added, and 110 minutes later a polymerization solution with a solid content of 54.2% was obtained.
After distilling off the vinyl acetate monomer, saponification was carried out by adding 440 parts of a 0.09N caustic soda methanol solution to 900 parts of a 40.3% methanol solution of the copolymer.
The obtained copolymer had excellent water solubility, consisted of 0.95 mol% of Nn-butoxyacrylamide units, 98.2 mol% of vinyl alcohol units, and 0.85 mol% of vinyl acetate units, and had a degree of polymerization of 1850. Example 8 To 496 parts of a methanol solution of the N-n-butoxymethylacrylamide-vinyl acetate copolymer obtained by copolymerization in Example 7, 111 parts of methyl acetate and
Saponification was carried out by adding 133 parts of 0.07N caustic soda methanol solution. The obtained copolymer has excellent water solubility and contains N-n-butoxyacrylamide units.
0.95 mol%, vinyl alcohol unit 83.40 mol%,
Consists of 15.65 mol% of vinyl acetate units, degree of polymerization
It was a copolymer of 1850. Example 9 In the same manner as in Example 6, 7500 parts of vinyl acetate, 11250 parts of methanol, 20 parts of N-n-butoxymethylacrylamide and 68 parts of 2,2'-azobisisobutyronitrile were charged to start polymerization. Inside N
210 parts of -n-butoxymethylacrylamide was added, and after 180 minutes, a polymerization solution with a solid content of 30.2% was obtained.
After distilling off the vinyl acetate monomer, saponification was carried out by adding 252 parts of a 0.26N caustic soda methanol solution to 642 parts of a 69.6% copolymer methanol solution. The obtained copolymer has excellent water solubility and N-n-
butoxymethylacrylamide units 2.0 mol%,
It was a copolymer containing 96.0 mol% of vinyl alcohol units and 2.0 mol% of vinyl acetate units, and had a degree of polymerization of 480. Example 10 To 287 parts of a methanol solution of the N-n-butoxymethylacrylamide-vinyl acetate copolymer obtained by copolymerization in Example 9, 53 parts of methyl acetate and
Saponification was carried out by adding 53 parts of 0.4N caustic soda methanol solution. The obtained copolymer has excellent solubility, although the aqueous solution is slightly cloudy, and is composed of 2.0 mol% of N-n-butoxyacrylamide units, 88.1 mol% of vinyl alcohol units, and 9.9 mol% of vinyl acetate units, and has a degree of polymerization of 480. It was a combination. Example 11 In the same manner as in Example 6, 7500 parts of vinyl acetate, 11250 parts of methanol, 750 parts of acetaldehyde, N-n
- 26 parts of propoxymethyl methacrylamide and 68 parts of 2,2'-azobisisobutyronitrile were charged to start polymerization, and during polymerization, 231 parts of N-n-propoxymethyl methacrylamide was added, and after 220 minutes.
A polymerization liquid with a solid content of 28.3% was obtained. After distilling off the vinyl acetate monomer and acetaldehyde, saponification was carried out by adding 111 parts of a 0.58N caustic soda methanol solution to 653 parts of a 75.9% copolymer methanol solution. The obtained copolymer has excellent water solubility and N-n
- It was a copolymer with a degree of polymerization of 220, consisting of 2.2 mol% of propoxymethylmethacrylamide units, 93.3 mol% of vinyl alcohol units, and 4.5 mol% of vinyl acetate units. Example 12 In the same manner as in Example 6, 1000 parts of vinyl acetate, 250 parts of methanol, 2 parts of N-n-hexoxymethylmethacrylamide and 0.5 part of 2,2'-azobisisobutyronitrile were charged and polymerization was started. , of N-n-hexoxymethyl methacrylamide during polymerization.
47.0 after 4 hours after adding 23 parts of 50% methanol solution
% solids content was obtained. After distilling off vinyl acetate, 40% copolymer methanol solution 100
saponification was carried out by adding 33 parts of 0.3N caustic soda methanol solution to one part. The obtained copolymer is N-
n-hexoxymethyl methacrylamide unit 0.9
It was a copolymer with a polymerization degree of 1730, consisting of 98.2 mol% vinyl alcohol units and 0.9 mol% vinyl acetate units. Example 13 In the same manner as in Example 6, 1000 parts of vinyl acetate, 667 parts of methanol, 1 part of N-2-ethylhexoxymethylacrylamide and 0.5 part of 2,2'-azobisisobutyronitrile were charged and polymerization was started. .
During the polymerization, 21 parts of a 50% methanol solution of N-2-ethylhexoxymethylacrylamide was added, and after 7 hours, a polymerization reaction solution with a solid content of 44.5% was obtained. After distilling off vinyl acetate, add 0.1N caustic soda methanol solution to 100 parts of 50% copolymer methanol solution.
Saponification was carried out by adding 100 parts. The obtained copolymer contained 0.6 mol% of N-2-ethylhexoxymethylacrylamide units and vinyl alcohol units.
It was a copolymer with a polymerization degree of 1070, consisting of 97.9% and 1.5 mol% of vinyl acetate units. Reference Example 1 A 9% aqueous solution of various modified PVA copolymers synthesized in Examples 1 to 11 (excluding Example 5) with
A predetermined amount of an aqueous sulfuric acid solution was added and mixed, and the pH (hydrogen ion concentration) was measured at 20°C, followed by film formation at 75°C for 1 hour to create a modified PVA film with a thickness of about 50μ. Measure the weight of this film sample (100mm x 100mm) either as it is or after heat-treating it in a hot air dryer for a specified time, and if the film retains its shape after immersing it in boiling water for 10 minutes, take it out and dry it completely. The subsequent weight was measured to determine the weight loss due to elution of the film with boiling water. The results are shown in Table 1. For comparison, the modified compound synthesized in Example 4
When film formation was performed without adding sulfuric acid to the PVA aqueous solution (Comparative Example 1) and unmodified PVA
(Comparative Example 2) was also shown in Table 1 when similar evaluation was carried out using (saponification degree 98.5 mol%, polymerization degree 1780). 【table】

[Brief explanation of drawings]

Figures 1 to 3 are proton nuclear magnetic resonance spectra with main frequency of 90MHz (VARIAN, EM-390)
These are all measurements of the modified polyvinyl alcohol copolymer solution of the present invention. FIG. 1 is a spectrum diagram of a heavy aqueous solution of N-methoxymethylacrylamide-vinyl alcohol-vinyl acetate copolymer, using trimethylsilylpropionic acid-d ₄ -sodium salt as a reference substance. Figure 2 is N
-n-butoxymethylacrylamide-vinyl alcohol copolymer dimethyl sulfoxide-d ₆
In the spectrum diagram of the solution, hexamethyldisiloxane was used as the reference substance. FIG. 3 is a spectrum diagram of Nn-butoxymethylacrylamide-vinyl alcohol-vinyl acetate copolymer, and trimethylsilylpropionic acid-d ₄ -sodium salt was used as the reference substance.

Claims (1)

[Claims] 1 An alkoxymethyl group-containing polymer represented by the formula CH ₂ =CR ¹ —CONHCH ₂ O—R ² (R ¹ means a hydrogen atom or a lower alkyl group, and R ² means an alkyl group). The monomer and the vinyl ester represented by the formula CH ₂ =CHOCOR ³ (R ³ means a hydrogen atom or a lower alkyl group) are copolymerized using a radical polymerization initiator, and then the copolymer is A vinyl alcohol copolymer having a crosslinkable group, which is characterized in that vinyl ester units in the copolymer are partially or highly saponified into vinyl alcohol units by the action of an alkaline catalyst on an alcohol solution. Production method. 2. The manufacturing method according to claim 1, wherein the vinyl ester is vinyl acetate. 3 The alkoxymethyl group-containing polymerizable monomer is N-
The manufacturing method according to claim 2, which is methoxymethylacrylamide. 4 The alkoxymethyl group-containing polymerizable monomer is N-
The manufacturing method according to claim 2, which is n-butoxymethylacrylamide.