JPS5859203A - Production of novel silicon-containing modified polyvinyl alcohol - Google Patents

Abstract

PURPOSE:To obtain a silicon-containing, modified polyvinyl alcohol suitable for use in paper coating agents, paints, etc., by copolymerizing a vinyl ester with a specified silicon-containing polymerizable monomer and saponifying the produced copolymer. CONSTITUTION:A vinyl ester (e.g., vinyl acetate) is copolymerized with a silicon-containing polymerizable monomer of formulaI, wherein R<1> is H or methyl, R<2> is H or a lower alkyl, R<3> is an alkylene or bivalent organic residue, R<4> is H, a halogen, lower alkyl, allyl or a like group, R<5> is an alkoxyl or acryloxyl and n is 0-2, in the presence of an alcohol by use of a radical polymerization initiator (e.g., benzoyl peroxide). The purpose modified polyvinyl alcohol having copolymer units of formula II, wherein R<6> is hydroxyl or acyloxyl, an alkoxyl, is prepared by saponifying the produced copolymer.

Description

[Detailed description of the invention]

The present invention is a novel silicon-containing modified polyvinyl alcohol (
The present invention relates to a method for producing polyvinyl alcohol (hereinafter abbreviated as PVA). Specifically, vinyl ester and a silicon-containing polymerizable monomer represented by the general formula % (1) are polymerized using a radial summerization initiator in the presence of alcohol. The present invention relates to a method for producing modified PVA containing a copolymerized unit represented by the general formula, which is characterized by saponifying a comonomer. (However, in formulas (■) and (It), R
1 is hydrogen or a methyl group, R2 is hydrogen or a lower alkyl group, R3 is an alkylene group or a divalent organic residue interconnected by a chain carbon-atomic pentate chain or nitrogen, R4
is hydrogen, hydrogen, a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group. ), R6 is a hydroxyl group, a salt of a hydroxyl group represented by the general formula OM (M represents an alkali metal or NH4), an alkoxyl group or an acyloxyl group (here, the alkoxyl group or the

[7 has a nitrogen-containing substituent and may be 10], n represents O~2) PVA is used as a raw material or as a sizing agent in a wide range of industrial applications.In the paper manufacturing industry, it is used as a coating agent for paper, such as a glue coating for surface sizing or as a binder in criminal coating. It is widely known that it has excellent performance that is unrivaled by other adhesives in terms of strength and film forming properties. However, in recent years, the concentration of sulfur in pulp raw materials has increased. As the surface strength tends to decrease as the ratio of blade materials increases, and as printing speeds tend to increase, there is a need for PVA that further improves the surface properties of paper, such as surface strength. There is a demand for PVA that can provide even higher barrier properties for barrier paper used in conventional PVA.
However, there was a drawback that these requirements could not be fully satisfied. The present inventors have sincerely researched a highly standard polymeric material that does not have such drawbacks, and have developed a polymerizable monomer containing viscous rice, vinyl ester, and a polymerizable monomer formed by the general formula. is polymerized using a radical polymerization initiator in the presence of alcohol F, and the copolymer is saponified to obtain a general formula (where R1, R2, K", R', R6, R
For example, when a modified PVA containing a copolymerized unit represented by 6, n is the same as Mli is used as a ruttle coating agent, special improvements such as paper strength on six sides and barrier properties can be made. It has the same performance as above average.
We discovered the fact that rfjAl is a polymeric material and arrived at the present invention. Conventional Kei Hongu Modified PVA
As a method, a method of saponifying a co-monomer of vinylalcoquine 7rane such as vinyltriethquine 7rane and vinyl acetate (Japanese Unexamined Patent Application Publication No. 1989-123,189) or a method of saponifying a comonomer of vinylalcoquine 7rane such as vinyltriethquine 7rane and vinyl acetate or in an organic medium such as triethylchloryl 7rane etc. Powdered PV by silylation of
A method in which hydrogen atoms in a package of hydroxyl groups of PVA are replaced by substituted silicon atoms (Japanese Unexamined Patent Publication No. 55-164)
, 614) etc. are known. [However, in the former method, the copolymerization resistance of vinyl alkoxy 7 run to vinyl acetate used is extremely poor, so the efficiency of introducing vinyl alkoxy/run units into the copolymer is low, and residual - The resulting denatured PvA tends to remain as
However, the latter method has disadvantages such as a tendency to reduce the degree of compatibility and difficulty in obtaining a high polymer. Q The inventor had various disadvantages such as being extremely disadvantageous in terms of writing and had great difficulties in industrial implementation. completed the rice milling invention, which was pursued with the aim of confirming the usefulness of silicon-containing modified PVA as described above, and also establishing a unique method for producing such modified PVA stably and effectively. Therefore, the modified PVA shown in the present invention is a novel compound previously unknown.That is, the object of the present invention is to produce modified P'V- A. The vinyl ester to be used in the present invention includes vinyl, vinyl propionate, vinyl formate, etc., but vinyl acetate is preferable from an economic point of view. As a specific example of the silicon-containing polymerizable monomer coated in the general formula, 3-(meth)acrylamidoprobyltrimethoxy7silane CMz=C-R-CNkl-(CH2)3.Si
(OCRs)8Δ 3-(meth)acrylamide-probyltrietoquinosilane C)I 2 亘■・CNH-(CH2)3.5i(O
CH+CHa) 3 fortune telling, Nio. 3-(meth)acrylamide-propyltri(β-methoxyeth υ) 3-(meth)acrylamide-propyltri(N-methylaminotri(N-methylamino)silane CH2=:CRoCNH(CH2)3.8i(OCHz)
C) lzNHcHa). 2-(meth)acrylamide-ethyltrimethoxy7rane l-(meth)acrylamide-methyltrimethoxysilane CH2=C1 CNHCHz-8i, (OCHa
)3CHa -CH2S s (OCHa )s SaH3 2-(meth)acrylamide-inproviltrimethquine 7 run i (OCRs )3 ♂H3 (R represents hydrogen or methyl group) (meth)acrylamide-linear chain or branched alkyltrialkoxysilane, N-(2-(meth)acrylamido-ethyl)-aminopropyltrimethoxysilanoCHz-CR-CONH-CHz CH2NH(CH;
), S i (OCH3)3(3-(meth)acrylamidoglobil)-oxypropyltrimethquine silane CH2=CR=CONH-(CH2)3=,0-(CH
(meth)acrylamido-nitrogen-containing or oxygen-containing alkyltrialkoxysilane such as 481 (OCRs) 3 (R represents hydrogen or methyl group), 3-(meth)acrylamidopropyltriacetoxysilane CHz-CR -CONH(CHz)3-8i
(OCOCHs)3CH2=CR-CONH(CH2
)281(OCOCHs)34-(meth)acrylamide-butyltriacetoxysilane CH2-CR-CON
H(Ckh)4Si(OCOCHa)33-(meth)acrylamidoprobyltripropionyloxonoCHz
-CR o NH (CH2), Si (OCOCH
2CH3)3Hs N-(2-(meth)acrylamido-ethyl)-aminopropylamido-alkyltriacyloxysilane, 3-(
meth)acrylamidoglobilisobuterdimethoxysilanoCH2=CR-CONH(CH2) 3Si(OCf(
a) 2CHa-CHCH2CHs 2-(meth)acrylamide-ethyldimethylmethoxysilane Ha CI+ =! ;R-CONH, (CH2) 2-8i
-0CHaCHa 3-(meth)acrylamidoglobiloctyldiacetoxycin Ct(2=CR-CONH(CH2)3Si(OC
OCHa ) 2(CH2') 7CHs 1-(meth)acrylamide-methylphenyldiacetoxysilane (l(2=CR-CONf(-CH2-8i(OCOC
Hs )2aha 3-(meth)acrylamido-propylbenzyljethoxysilane CH2=CR-CONH-(CHa)3-8i-(OC
HaCHs)2CH2-CrHg 2-(meth)acrylamido-2-methylpropylmonochlorodimethoxysilane CH2=CH-C0NH-C(CHs) 2-CHz
Si (OCHs) (-meth)acrylamidoprokyl di- or monoalkoxy numbers such as 2-(meth)acrylamido-2-methylpropylhydrodiene dimethoxysilane (R represents hydrogen or methyl group) or Mono, acetic disilane, 3-(N-methyl-(meth)acrylamide)-propyltrimethoxysilane. CH2=CR-CON-(CH2)3-8L(OCHs
)aCHs Below margin 2-(N
-ethyl-(meth)acrylamide)-ethyltriacetoxysilane. C) 12 = Cft-C0N-CHzCHz 5t(O
eOC)Is)3HzCHs (R represents a water column or a methyl group)
Examples include (meth)acrylamide) trialkoxy or triacetoxysilane. Among these, 3-(meth)acrylamidoglopyrutrimethoxy 72/& and 3-(meth)acrylamidoglopyrutriacetoxysilane are relatively easy to manufacture and inexpensive, and 2- (Meth)acrylamido-2-methylglobiltrimethoxysilane and 2-(meth)acrylamido-2-methylglobiltriacetoxysilane are preferably used because their amide bonds are extremely stable against acids or alkalis. - The copolymerization of the silicon-containing polymerizable monomer, vinyl ester, and sieved vinyl acetate described above is preferably carried out by solution polymerization in the presence of alcohol. The alcohol is usually lower alcohol such as methanol or ethanol, which is industrially preferable. It is also possible to carry out the process using either a batch polymerization method or a continuous method. In the case of a batch system, it is well known that the copolymer composition fluctuates with the polymerization rate according to the copolymerization reactivity ratio (11% rr). In order to obtain a copolymer having a uniform copolymerization composition, it is desirable to adopt the so-called semi-batch p method in which both monomers are added. An example of how to calculate the amount added in this case is that R, J, Hanna is Industrial, an
dEngineer, ringChemistry. Vol, 49', A2, 208-! 09 (1957)K
For the same reason, monomers are added to the second and subsequent columns so that the monomer composition in each column is constant. It is desirable to add As a polymerization initiator, 2,2'-azobisisobutyronitrile, benzoyl peroxide, superfused lauroyl,
Known radical polymerization initiators such as acetyl peroxide can be used. The temperature for the polymerization reaction is usually within the range of 50°C to the boiling point of the polymerization system. In addition, in addition to the above two components, the vCh used for such polymerization may also contain other unsaturated substances copolymerizable with such monomers, such as styrene, alkyl vinyl ether, ethylene, propylene, 6α-↑xeno, and α-octene. olefins, unsaturated acids such as (meth)acrylic acid, crotonic acid, (anhydrous) maleic acid, fumaric acid, itaconic acid, and their alkyl esters, alkyl salts, 2-acrylamido-2-methyl Sulfonic acid-containing monomers such as propanesulfonic acid and their alkali salts, trimethyl-3-(1-acrylamido-1,1-dimethylglobyl) ammonium chloride, trimethyl-3-(1-acrylamidopropyl) ammonium chloride, 1 -Vinyl-2-methylimidazole and its quaternary compound, cationic monomer, etc., can also be present in small proportions. The amount of silicon-containing polymerizable monomer units in the copolymer is appropriately selected depending on the application and is not particularly limited, and a copolymer having an arbitrary composition can be synthesized. Further, the degree of consideration of the copolymer can be arbitrarily adjusted by detecting the alcohol in the solvent and checking the violet. After the copolymerization is completed, if vinyl ester remains in the reaction solution, it must be removed by distillation or the like. If the silicon-containing polymerizable monomer remains, it may be removed separately from the vinyl ester, or if it is a small amount, it may remain, and even if it remains, it will not be useful for general purposes. The comonomer thus obtained is then saponified. The saponification reaction is usually carried out in the form of an alcohol solution, and it is advantageous to carry out the reaction by alcoholysis. Not only anhydrous alcohols but also hydrous alcohols such as Yuha can be used depending on the purpose. Further, the alcohol may optionally contain a suitable solvent such as methyl acetate or ethyl acetate. As the curing catalyst, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alcoholades such as sodium methylate and potassium methylate, or alkaline catalysts such as ammonia are used, and plate catalysts such as hydrochloric acid and sulfuric acid are used. can also be used. Among these, alkali catalysts are advantageous in terms of fast saponification and rapid expansion, and among these, sodium hydroxide is advantageous from an industrial standpoint because it is economical. The saponification temperature is usually selected from the range of 1O to 50"C. In the copolymer of the present invention, the ad-do bond of the silicon-containing polymerizable monocapsular unit decomposes in the saponification reaction using an acid catalyst or an alkali catalyst. In the saponification reaction, vinyl ester units are partially or highly saponified and converted into vinyl alcohol units, but this conversion rate, that is, the degree of saponification, It can be set to any value depending on the purpose of use of PVA. In addition, during the saponification reaction, the silicon-bonded alkoxyl groups, carboxyl groups, hydrogen, and halogens of the silicon-containing polymerizable monomer unit represented by general formula (1) are simultaneously partially or highly saponified, and the hydroxyl groups or It is converted to an alkali salt of hydroxyl group. Furthermore, some of these hydroxyl groups or alkali salts of hydroxyl groups may be bonded to each other to form siloxane bonds depending on the drying conditions when the modified PVA obtained after the saponification reaction is dried. Modified PVA in which many siloxane bonds are formed is insoluble in water, but can be made water-soluble by using a small amount of alkali. In such cases, silicon-containing polymeric compounds*1 have a surprisingly high redundancy with respect to alkalis (meta).
Preference is given to modified PVA with acryloid-branched alkylsila 7 positions. The silicon-containing modified PVAFi powder of the present invention can be stored and transported, and when used, it can be used in powder form or in a dispersed state in a compact, but it can be used as a homogeneous water bath solution. During this dispersion, if necessary, a small amount of an alkali such as sodium hydroxide or ammonium hydroxide is added as described above, and by heating while stirring, a uniform -at- can be obtained. Furthermore, it is also possible to add an alkaline earth metal to the above aqueous solution and use a part of the hydroxyl groups bonded to the silane as an alkaline earth metal salt. As mentioned above, the new copolymer obtained by the present invention has excellent performance as a coating agent for paper, but in addition to this, it is possible to utilize the properties of the hydroxyl group and vinyl ester group and the function of the silane-based reactive group. It can demonstrate excellent performance in a variety of applications. Please use the paper's internal poise agent 1HILLllI! Sizing agents for products, warp glue, fiber strength 1 agent, paint, glass fiber coating agent, gold 1F4 (D surface coating agent, anti-fog agent) coating agent, wood, paper, aluminum foil, small plastic adhesives, non-woven fabric binders, fibrous binders, binders for building materials such as gypsum board and fiberboard, thickeners for various emulsion adhesives, machining for urea, pyrolyte adhesives, cement, etc. Additives for mortar, hot melt type adhesive cutting), various adhesives such as pressure sensitive adhesives, ethylene-based non-containers such as ethylene, styrene, vinyl acetate, (meth)acrylate, vinyl chloride, vinylidene chloride, acrylonitrile, etc. Dispersants for emulsion polymerization of saturated monomers and PTADIER/1 unit, pigment dispersion stabilizers for obstetrics, adhesives, etc., vinyl chloride, vinyl chloride/, styrene/, (meth)acrylic fine ester, vinyl acetate, etc. Dispersion stabilizer for suspension polymerization of each hinoki ethylenic fushowadandensen, fibers, films, sheets, pipes,
Materials related to tubes, water-soluble fibers, temporary coatings, etc., hydrophilicity imparting agents for hydrophobic resins, blending agents for synthetic resins such as additives for composite fibers, films, and other molded products, soil quality. It can be used as an improvement agent, soil stabilizer, etc. Next, the present invention will be explained in more detail with reference to examples, but these examples are not intended to limit the present invention in any way. Examples A, Part or H refer to 9 parts by weight or weight, unless otherwise specified. Example 1 2700 fm of vinyl acetate, 6 ml of methanol were placed in 9 reaction vessels equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser.
00 parts of 3-acrylamide-propyltrimethoxine and 2.7 parts of 3-acrylamide-propyltrimethoxine were added, and the system was purged with nitrogen while stirring, and then the internal temperature was raised to 60°C. To this system, 200 seconds of a methanol solution containing 1.89 parts of 2,2'-azobisinobutyronitrile was added to initiate polymerization. From the start of the polymerization, 74.6 parts of a methanol solution containing 3-acrylamide 1'-globylmerimethoxyl was poured into the system, and the polymerization was continued for 3 hours. The solid content in the system a1 degree at the time of termination of polymerization was 35 degrees. By introducing methanol vapor, unreacted vinyl acetate polymer was expelled, and a 35-methanol solution of the copolymer was obtained. , this copolymerization “body is 3
-Acrylamidoglopyrtrimer? Nuclear magnetic resonance analysis revealed that the fermented product contained 0.5 mole of silane units and 99.5 mole of vinyl acetate units. While stirring 1σO part of a methanol solution of this copolymer at 40°C, a methanol solution containing 4 mol of sodium hydroxide per vinyl acetate unit was added to carry out a conversion reaction to obtain kO. The white gel was crushed, thoroughly washed with methanol to remove unreacted 3-acrylamide globiltrimethoxysilane, and dried to remove the modified P.
Got a VA. The obtained modified PvAFi was determined by infrared spectroscopy.
The presence of an amide bond was determined from the absorption at 1N91 cm'' and 1540 cm' (K2 amide group), and the presence of silica atoms was confirmed by atomic absorption analysis. Also, by nuclear magnetic resonance analysis, δ = 3.4. The presence of a methoxy group bonded to a silicon atom was confirmed from the rlflD peak. From these methods, it was confirmed that the modified pvAo characteristic values were as follows: 3-acrylamidonipropylsilane position; 0.5 mole - methoxy group and hydroxyl group bonded to silicon atom are respectively 10 mole - 190 mole%/(3-acrylamide-
Propylsilane group x 3) Vinyl alcohol unit: 99.
0 moles of vinyl acetate units; 0.5 moles of 4Is aqueous solution viscosity at 20°C; It can be seen that this is a coelectrolyte having a structure in which 90 moles of the methoxy group of the noramidopropyltrimethoxysilane unit and 99.5 moles of the vinyl acetate unit are saponified. Example 2 Reactor similar to Example 1 1,050 parts of vinyl acetate, 2,000 parts of methanol, and 70.63 parts of 3-acrylamide-propyltriethoxysilane were charged into the system, and while stirring, the inside of the system was flushed with nitrogen, and the internal temperature was raised to 60°C. 450 parts of a methanol solution containing 21 parts of 2,2'-azobisisobutyronitrile was added to this system to initiate polymerization. From the time of coagulation and condensation, 3-acrylic acid was added to the methanol bath containing 6.7 parts of doglobil triethoxy 7 run and 27 parts of 2 yarns, and the polymerization was continued for 3 hours. The solid content concentration in the system at the time of termination of polymerization was 21%. After expelling the unreacted vinyl acetate violet by introducing methanol vapor,
A copolymer of 35% methanol camellia solution was obtained. This copolymer contained 0.3 mol 3-acrylamidoglobil triethoxysilane units and 997 mol ts vinyl acetate units.
Containment was confirmed by nuclear magnetic resonance analysis. A methanol solution containing 0.8 mol of sodium hydroxide per vinyl acetate unit was added to 100 parts of a methanol solution of this monomer while stirring at 40° C. to carry out a saponification reaction. The obtained white gel was crushed, thoroughly washed with methanol to remove unreacted 3-acrylamide globil triethoxysilane, and then dried to obtain modified PVA. This modified PVA was analyzed in the same manner as in Example 1, and it was confirmed that it was a copolymer having the following characteristic values. 3-acrylamide globil 7 run position 0.
3 mole vinyl alcohol unit 8
7.7 mole dominant vinyl acetate units
12. Viscosity of 4-ti aqueous solution at 20℃
Example 3 In a reactor similar to Example 1, 28θθ parts of vinyl acetate,
500 g of methanol and 5.6 g of 2-acrylamido-2-methylglobyltrimethoxysilane were charged, and after the t-chain was replaced in the system with stirring, the internal temperature was raised to 60°C. In this system, 2,2'-azobisisobutyronitrile 1
．． 200 parts of a methanol bath solution containing 96m was added to initiate polymerization. 2-acrylamide-2- from the start of polymerization
The reaction was continued for 3 hours while adding 150 parts of a methanol solution containing 37.4 parts of methyl A 7'robiltrimethoxysilane to the system. Solid content in the system S degrees t when polymerization is stopped
The i was 35%. After expelling unreacted vinyl acetate monomer by introducing methanol vapor, the 3゛5
Chi'i1. It was confirmed by nuclear magnetic resonance analysis that it had 0 mole φ and 99 mole φ of vinyl acetate units. While stirring 100 parts of a methanol solution of this copolymer at 40°C, a methanol bath solution containing 5.0 mol φ of sodium hydroxide per vinyl acetate unit was added to perform curing reaction expansion. Ta. The resulting white gel was crushed, thoroughly washed with methanol, and unreacted 2-acrylamide was removed.
After removing the 3-methylglobil trimethoxysilane monomer, it was dried to obtain modified PVA. This modified PVA is prepared by dispersing sodium hydroxide in water and adding 0.5% sodium hydroxide to the modified PVA.
% and heating, it was possible to easily form a homogeneous aqueous solution. This modified PVA was analyzed in the same manner as in Example 1 and was confirmed to be a copolymer having the following characteristic values. In this case, viscosity measurement or nuclear magnetic resonance analysis was performed using water or a heavy aqueous solution containing 0.5% sodium hydroxide for modified PVA, and infrared absorption analysis was performed using a film made from this aqueous solution, and vinyl acetate units is vinyl alcohol unit in chemical analysis 9
8.9 moles - vinyl acetate units
0.1 mol - Viscosity of 4-ti aqueous solution at 20℃
29.7 centivoids Example 4 - In a reactor similar to Example 1, 1400 parts of vinyl acetate,
Polymerization was started by adding 600 parts of a methanol solution containing 1500 parts of methanol, 8.4 parts of 2-acrylamide-27methylpropyltrimethoxysilane, and 28 parts of tributyronitrile. 2-acrylamide-2- from the start of polymerization
Polymerization was continued for 3 hours while adding 357 parts of a methanol solution containing 89.3 parts of methylglobiltrimethoxysilane to the system. When the polymerization was stopped, the solid content in the system was tFi 28 . After expelling unreacted vinyl acetate monomer by introducing methanol vapor, a methanol solution of copolymer 351 was obtained. This copolymer is 2-acrylamide-2
It was confirmed by +A magnetic resonance analysis that the metherglopyltrimethoxy/silane had an independent life of 3.0 mol φ and an acetic acid-vinyl 4-position concentration of 97 mol. A saponification reaction was carried out by adding a methanol solution containing 8.0 mol of sodium hydroxide to the vinyl acetate unit in the V-vinyl acetate unit at ℃ while stirring. After thoroughly washing with methanol to remove unreacted 2-acrylamide-2-meterpyltrimethothodisilane, it was dried to obtain modified PVA. Add 1 inch to PvA and heat it.
A was analyzed in the same manner as in Example 1, and it was t*WL that it was a copolymer having the following analytical values. At this time, viscosity measurement or nuclear magnetic resonance analysis was performed using a water or heavy aqueous solution containing 1% sodium hydroxide for modified PVA, and infrared absorption analysis was performed using a film made from this aqueous solution, and vinyl acetate units were determined by chemical analysis. Each was measured. 2-acrylamido-2-methylglobylsilane unit
30 mol - Vinyl alcohol J4L position 96.9 mol - Vinyl acetate units 0.1 mol ts Viscosity of 4-tear water solution at 0°C 7.0 sennapoise Example 5 In a reactor similar to Example 1, vinyl acetate 1050 Department,
After charging 2000 parts of methanol and 0.7 s'x of 3-acrylamide-propyltriacetoxysilane and purging the system with nitrogen while stirring, the internal temperature was raised to 60°C. To this system, 450 parts of methanol containing 15 parts of 2,2'-azobisisobutio=)dyl was added to initiate polymerization. From the start of the polymerization, 27 parts of a methanol solution containing 7 parts of 3-acrylamidoglopyrut-acetoquine silane was applied to the system, and the polymerization was continued for 3 hours by Tsujito et al. The degree of separation in the thread at the time of termination of polymerization was 20%. The unreacted vinyl acetate single body was expelled by Hirohito in the heat of methanol, and the π-isomer was removed.
A 35-timethanol solution of the copolymer was obtained. While stirring 100 parts of a methanol solution of this copolymer at 40 DEG C., a methanol bath solution containing 2 mol of sodium hydroxide per vinyl acetate unit was added to carry out a saponification reaction. The obtained white gel was pulverized, thoroughly washed with methanol to remove unreacted 3-acrylamide-propyltriacetoxysif/monomer, and dried after death to obtain modified PVA. This modified PVA was analyzed in the same manner as in Example 1, and it was confirmed that it was a copolymer having the following characteristic values. 3-tecrylamide probyl silane position 0
．． 25 mole vinyl alcohol units
99.7 molar vinyl acetate units
0.05 mol - viscosity of aqueous solution of 4 at 20℃*
6.5 centivoids Examples 6 to 11 Modified PVA was obtained in the same manner as in Example 1, except that the copolymerization reaction was carried out using the conditions shown in Table 1, and the products were confirmed. Show the results in the first layer〇】So [margin

Claims (1)

[Claims] Copolymerizing a vinyl ester and a silicon-containing polymerizable monomer represented by the general formula using a radical polymerization initiator in the presence of alcohol, and saponifying the resulting copolymer. A method for producing modified polyvinyl alcohol containing a copolymerized unit represented by the general formula, characterized by: However, in formulas (I) and (If), R1 is hydrogen or a methyl group, B2 is hydrogen or a lower alkyl group, and Ra is an alkylene group or a divalent organic residue in which chain carbon atoms are bonded to each other by oxygen or nitrogen. is hydrogen, a halogen, a lower alkyl group, an allyl group, or a lower alkyl group having an allyl group; R5 is an alkoxyl group or an acyloxyl group (wherein the alkoxyl group or !siloxyfluor group has a substituent containing oxygen or nitrogen; good)
, R@ is a hydroxyl group, a salt of a hydroxyl group represented by the general formula OM (M
represents an alkali metal or h''H4), an alkoxyl group or an acyloxyl group (wherein the alkoxyl group or the acyloxy group may have a substituent containing oxygen or nitrogen), n is θ~2 are respectively represented.