JPS59179605A - Production of modified polyvinyl alcohol having silyl group bonded to alkoxyl group - Google Patents

Abstract

PURPOSE:To obtain a modified PVA which forms a difficultly thickening aqueous solution and forms a water-resistant film, by saponifying a copolymer of a vinyl ester with an olefinically unsaturated monomer having a silyl group bonded to a secondary alkoxyl group. CONSTITUTION:The titled modified PVA is obtained by copolymerizing a vinyl ester (e.g., vinyl acetate) with an olefinically unsaturated monomer having a silyl group bonded to a secondary alkoxyl group, of formula I or II (wherein R<1> and R<5> are each H or CH3, R<3>, R<3>, and R<4> are each a lower alkyl, allyl, or an allyl- containing lower alkyl, A is a bivalent organic residue which may contain an O- or N-containing group, and n is 0-2), e.g., vinyltriisopropoxysilane or 3-(meth) acrylamido-propyltriisopropoxysilane, in the presence of a radical polymerization initiator, and saponifying the produced copolymer. This modified PVA can form a stable aqueous solution difficult to thicken and can form a water-resistant film.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing modified polyvinyl alcohol (hereinafter polyvinyl alcohol will be abbreviated as PVA) having a silyl group bonded to an alkoxyl group. More specifically, vinyl ester and the general formula R' R2n kl, , 3 Cf (2 = 8-4i-(0 and H-R') 3-n (1) or (where R1 and 15 are hydrogen atoms or methyl groups) , R2
゜H3, H4 are the same or different lower alkylyl groups, lower alkyl having an allyl group, divalent organic residues which may have oxygen or nitrogen-containing groups, n represents O~2, respectively) An alkoxyl polymerization method characterized by copolymerizing a secondary alkoxyl group and an olefinically unsaturated monomer having a bonded silyl group using a radical polymerization initiator, and saponifying the obtained copolymer. Modified Polyvinyl Alcohol Containing Silyl Groups Conventionally, the method for producing modified PVA containing silyl groups is to react powdered PVA with a silylating agent such as methyl trichloro 7ran in an organic bath medium, and remove hydrogen from some of the hydroxyl groups of PVA. Method of substituting atoms with substituted silicon atoms (Japanese Patent Application Laid-Open No. 55-164, 61
4) t' or (2) A method of saponifying a copolymer of vinyl alkoxy 7-ranes such as vinyltriethoxysilane and vinyl acetate with a sonic alkali (Japanese Patent Application Laid-Open No. 50-123, 1
89) is known. However, method (1) has drawbacks such as: (1) it is difficult to obtain a modified product with a uniform composition; and (2) the reaction must be carried out again in addition to the production of PVA, which is extremely disadvantageous in terms of process. In addition, in the method (2), specifically, it is known that vinyltriethoxysilane and vinyl acetate are copolymerized, and the ethoxyl group bonded to the silyl group is completely hydrolyzed by saponification with an alkali. Only.

According to detailed experiments conducted by the present inventors, modified PVA obtained by saponifying a copolymer of vinyl silane having some alkoxyl groups such as vinyltriethoxysilane and vinyl acetate with an alkali is In fact, the alkoxyl group bonded to the 7lyl group is easily hydrolyzed, and the silyl group is converted into a silyl group without an alkoxyl group, which tends to form a crosslinked structure, making it essentially difficult to dissolve in water.
To understand this, it is necessary to add nitrate to the glutinous alkali, and this aqueous solution has a tendency to thicken and has poor stability. There are various drawbacks such as insufficient.

As a result of intensive studies aimed at overcoming the above-mentioned drawbacks, the present inventors found that vinyl ester and the general formula (I) or (■) -R') Oh.
(1) (here R1, B:2, R3, R', R"
, A, n are the same as above) and an olefinically unsaturated olefinically unsaturated silyl bonded to a secondary alkoxyl group represented by 1.
Surprisingly, the secondary alkoxyl group bonded to the silyl group remains bonded to the silyl group without being completely hydrolyzed during saponification. In other words, the hydrolytic freshness of the secondary alkoxyl group can be made to be 95 mol or less, preferably 85 mol or less, and the resulting modified PVA in which the silyl group bonded to the alkoxyl group is In addition, it was discovered that it is water bathable, has good viscosity stability in aqueous solutions, and has excellent reactivity and adhesion to inorganic substances, leading to the completion of the present invention.

Vinyl acetate used in the present invention includes vinyl acetate, vinyl propionate, vinyl acetate, etc., but vinyl acetate is preferred from an economic standpoint. In addition, examples of the olefinic unsaturated olomonomer having a /lyl group bonded to a secondary alkoxyl group represented by the general formula (1) that are used in the present invention include vinyl triisoproboxyl 7-lane, vinyl tri-2- Methylpropoxysilane, isoprobenylisochloroboxy/lane, vinylmethyldiisopropoxysilane, vinylmethyldiisopropoxysilane,
Vinyltri-1-phenylethoxysilane, vinyltri-2-phenylpropoxysilane and the like are preferred, but vinyltriisopropoxysilane is preferred from an economic standpoint.

In addition, the olefinically unsaturated monomer having a silyl group bonded to a secondary alkogyl group represented by the general formula (If) used in the present invention is 3-(meth)acrylamidopropyltri. Noproboxy7silane, 3-(meth)
Acrylamide-propyltri2-methylpropoxysilane, 2-(meth)acrylamide-2-methylpropyltriisoproboxysilane, 2-(meth)acrylamide-2-methylethyltri2-methylpropoxysilane, N-(2 -(meth)acrylamido-ethyl)-aminopropyltriisopropoxysiphne, 3-(meth)
Acrylamide dopropyl methane silane, a-(N-methyl-(ivy)acrylamide゛)-
Probiltos inoprofokifusilane, 3-(meth)acrylamide-methoxy-3-hy]roxyprovir) l) Inoprofokifusilane, 3((meth)acrylamide-methoxy)-probyltriisogloboxycidine, dimethyl -3-(meth)acrylamide-propyl-3-(triisopropoxyzolyl)propylammonium chloride, dimethyl-2-(meth)acrylamide-2-methylpropyl-3-(triinepropoxysilyl)propylammonium chloride, etc. can be mentioned.

In the present invention, the copolymerization of these monomers can be carried out in either a batch system or a continuous system. In the case of a 60-batch system, the copolymerization rate and the copolymerization rate vary according to the copolymerization reactivity ratio (rl, r2). It is well known that the composition fluctuates, but it is best to adopt the so-called half-batch method in which 10,000 or both of the monomers are subjected to total resistance so that the monomer composition remains constant. In order to obtain a copolymer having a copolymerization composition, nitrates are used. An example of how to calculate the amount added in this case is that g J, , tanna is Industrial
and Engineer Chemxtry
, Vol, 49.16.2.208-209 (19
57) can be cited. In the case of continuous multi-column copolymerization, for the same reason, it is desirable to cool the monomers in the second and subsequent columns so that the monomer composition in each column is constant. As the polymerization initiator, known radical polymerization initiators such as 2°2'-azobisisobutyronitrile, benozoyl peroxide, lafuroyl peroxide, and acetyl peroxide can be used. The polymerization reaction temperature is within the normal range of 50°C to polymerization thread temperature.The copolymerization of the above-mentioned silyl group-containing olefinic unsaturated monomer and vinyl ester, especially vinyl acetate, is a polymerization reaction temperature of 50°C for polymerization. It is preferable to carry out the polymerization by solution polymerization under direct supervision. Generally speaking, lower alcohols such as methanol and ethanol are preferred industrially.Also, when carrying out such polymerization, there are other disadvantages such as copolymerization with monomers other than the two components. olefins such as styrene, alkyl vinyl ether, vinyl versatate, (meth)acrylamide, ethylene, propylene, α-hexene, α-octene, (
meth]acrylic acid, phosphoric acid, (m-water) unsaturated acids such as maleic acid, fumaric acid, and itaconic acid, and their alkyl esters, alkali salts, and sulfones such as 2-acrylamido-2-methylpropanesulfonic acid. Acid-containing monomers and their alkali salts, trimethyl-2-(1-acrylic, ethylamide-1,1-dimethyl-i) ammonium chloride, trimethyl-3-(1-acrylamidopropyl) ammonium chloride, 1- It is also possible to contain -81:δ in small proportions of cationic monomers such as vinyl-2-methylimidazole and its derivatives.

The amount of the silyl group-containing olefinically unsaturated monomer unit in the copolymer is appropriately selected depending on the application, and is not particularly limited, but is preferably 0.01 to 10 mol, most preferably 0.1. ~
It is 2.5 moles. If vinyl ester remains in the reaction solution after copolymer composition, it is necessary to remove it by distillation or the like. If the silyl group-containing olefinically unsaturated monomer remains, it may be removed separately from the vinyl ester, and a small amount of mefL may be allowed to remain for general purposes.

The copolymer thus obtained is then saponified. The saponification reaction is usually carried out in a copolymer all-alcohol bath solution.
It is advantageous to carry out the entire reaction with alcohol. Not only anhydrous alcohols but also alcohols containing a small amount of water can be used depending on the purpose. Further, the alcohol may optionally contain an organic solvent such as methyl acetate or ethyl acetate. As saponification catalysts, alkali metal hydroxides such as hydroxide, potassium hydroxide, alcolades such as sodium methylate and potassium methylate, or alkali catalysts such as Vammonium hydroxide, etc. are used. ,
Acid catalysts such as hydrochloric acid and sulfuric acid can also be used. Among these catalysts, alkaline catalysts are advantageous in that they have a fast saponification reaction rate, and sulfur and lithium hydroxides are economically advantageous from an industrial standpoint. The saponification temperature is usually selected from the range of 10 to 50°C.

Through the saponification reaction, the vinyl ester units are partially or severely saponified and converted into vinyl alcohol units, and this conversion rate, that is, the degree of saponification is preferably 60.
˜100 mol, optimally between 70 and 100 mol. In addition, the hydrolytic freshness of the secondary alkoxyl group bonded to the silyl group is 95 molar or less, preferably 85 molar or less, but if too much catalyst is used during the saponification reaction, general formula (1) Since the secondary alkoxyl group bonded to the silyl group represented by (If) also tends to be easily hydrolyzed, the amount of saponification catalyst used is 0 as a molar ratio to the total monomer units in the copolymer. ,05~0.0
01, more preferably 0.03 to 0.005. The degree of polymerization of the resulting modified PVA can be arbitrarily adjusted depending on the type and amount of alcohol used during the polymerization reaction, but it is usually 300 to 3000 (3 to 100 centiboise as Brookfield viscosity of a 4% aqueous solution at 20°C). is.

The modified PVA having a silyl group bonded to an alkoxyl group of the present invention can be stored and transported in powder form, and when used, it can be used in powder form or dispersed in a liquid, but when used as a homogeneous aqueous solution. When used, a uniform paste solution can be obtained by dispersing it in water and heating it while stirring.

As mentioned above, the modified PVA having a silyl group bonded to an alkoxyl group obtained by the method of the present invention is water bathable, has excellent viscosity stability in an aqueous solution, and has excellent water resistance, reactivity to inorganic substances, and adhesion. It exhibits unambiguous performance in a variety of applications that take advantage of this performance and the performance of the vinyl ester group. For example, internal sizing agents for paper, coating agents for paper, sizing agents for textile products, warp sizing agents, fiber processing agents, paints, coating agents for glass fibers, surface coating agents for metals, coating agents such as antifogging agents, etc. Adhesives such as Mokugan, Nagi, aluminum foil, plastic, etc.
Non-woven fabric binders, fibrous binders, binders for building materials such as gypsum board and fiberboard, thickeners for emulsion yarn adhesives for various poles, elephant additives for urea-based adhesives, hemp agents for cement and hemp, Various adhesives such as hot-melt adhesives and pressure-sensitive adhesives, ethylenically unsaturated monomers such as ethylene, styrene, vinyl acetate, (meth)acrylate, vinyl chloride, vinylidene chloride, acrylonitrile, and butadiene. Dispersant for emulsion polymerization of thread monomers,
Pigment dispersion stabilizer for paints, adhesives, etc., dispersion stabilizer for suspension polymerization of various ethylenically unsaturated monomers such as vinyl chloride, vinylidene chloride, styrene, (meth)acrylate, vinyl acetate, fibers, and films. , molded products such as sheets, pipes, tubes, water-soluble fibers, temporary coatings, hydrophilicity imparting agents for hydrophobic resins, blending agents for synthetic resins such as composite fibers, films, and additives for molded products, soil improvement. It is used as a 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. In the examples, unless otherwise specified, parts or parts indicate parts by weight or % by weight.

Example 1 Vinyl acetate 2800T was placed in a reaction vessel equipped with a stirrer, thermometer, dropping funnel, nitrogen gas introduction tube and reflux condenser.
f15, 300 parts of methanol, and 43 parts of vinyltriisopropoxysilane were charged and the inside of the system was purged with nitrogen while stirring, and then the internal temperature was raised to 60°C.

In this system, 2,2'-an:bisisobutyronitrile 39
Add all 4.00 parts of methanol containing 1 part to start N-combination. , M! The match was stopped at the first stop, three hours after the start of the interval. The solid content in the system at the time of termination of polymerization was 42.
I got 1-. After all unreacted vinyl acetate monomer was expelled by introducing methanol vapor, a 50% methanol solution of the copolymer was obtained. This copolymer was confirmed by nuclear magnetic resonance analysis to contain 0.40 molar units of vinyl triimproboxylene units and 99.6 molar units of vinyl acetate units. 100 parts of a methanol solution of this copolymer was stirred at 40°C, and 1 part of sodium hydroxide was added to it.
0% methanol 3.2 parts (alkali molar ratio 0.01
4) Saponification reaction was carried out by gradual addition. The obtained white gel was crushed, thoroughly washed with methanol, and mixed with wood ash for 5 minutes.
The vinyltriisopropoxysilane was removed and dried to obtain modified PVA.

The obtained modified PVA contained 0.38 mol% (hydrolysis degree of isopropoxyl group is 5 mol) of silyl groups as vinylsilane units, which were bonded to isopropoxyl groups by skeleton magnetic resonance fractionation. Also, chemical analysis showed that the degree of saponification of vinyl acetate units was 92. '''44 molty. This modified PVA can be dissolved in water, and the modified PVA
The viscosity at 20°C of a 4% aqueous solution of was 20 centipoise (hereinafter abbreviated as centipoise Cp) (as measured by a Brookfield viscometer). This modified PVA
There was no change in the viscosity of the 10% aqueous solution when it was left at 30°C for one week. An aqueous solution of octopus was cast onto a polyethylene film, dried at room temperature for 3 days to form a film, and then the film was immersed in a 1/2 normal acid bath and immersed in comb water. When this film was dissolved in water, it was found that the water resistance was surprisingly high. Comparative Example 1 In a reaction vessel similar to Example 1, 2800% vinyl acetate was added.
After charging 300 parts of methanol and 35 parts of vinyltriethoxysilane and substituting crab element into the thread I'9' while stirring,
The internal sound rose to 60 degrees Celsius. A methanol solution containing 3.9met of 2,2'-azobisisobutyronitrile was added to this system.
0 parts was added to completely start the polymerization, and the polymerization was continued for 3 hours. The solid content concentration was 36.9%. A 50% methanol solution of the copolymer was obtained in the same manner as in Example 1 by introducing methanol vapor. It was confirmed by nuclear magnetic resonance analysis that this copolymer contained an average of 0.40 mol of vinyltriethoxysilane units and 99.6 mol of vinyl acetate units. Modified PVA was obtained by saponification, washing and drying in the same manner as in Example 1. The resulting modified PVA was determined to contain 0.40 molar units of silyl groups as total vinyl 7 run units by atomic absorption analysis, and the degree of saponification of vinyl acetate units was determined to be 92.0 molar by chemical analysis. This modified PVA
It does not dissolve in water without alkali, and is made into an aqueous solution.There was a heart wall to which IJium was added (more than 1% hydroxide to this modified PVA). This degeneration 1”V
20% of a 4% water bath solution of this modified PVA obtained by dissolving 2.5% of sodium hydroxide in aqueous solution of A
The viscosity at °C was 20 (!p), and nuclear magnetic resonance analysis of this aqueous solution confirmed that there was no ethoxyl group bonded to the silyl group. A 10% aqueous solution of
When left alone, the viscosity increased over time. Furthermore, a film was prepared from this aqueous solution in the same manner as in Example 1, and when placed in boiling water in the same manner as in Example 1, it dissolved in a short time.

Example 2 In a reaction vessel similar to Example 1, 2800 parts of vinyl acetate,
After charging 400 parts of methanol and 53 parts of vinyltriisopropoxysilane and purging the system with gold nitrogen while stirring, the internal temperature was raised to 60°C. A methanol solution containing 1.96 parts of 2,2'-azobisisobutyronitrile was added to this system.
00 parts were added to start polymerization. While measuring the polymerization rate and measuring the concentration ratio of the remaining monomers by gas chromatography from the start of polymerization, vinyltriisopropoxysilane 6 was added so that the concentration ratio of the remaining monomers was always constant.
．． The weight loading was continued for 4 hours while continuously adding 46 parts of methanol solution containing 0 parts to the system. The solid content concentration in the system at the time of termination of polymerization was 40%. After expelling unreacted vinyl acetate monomer by introducing methanol vapor, a 35% methanol solution of the copolymer was obtained. Nuclear magnetic resonance analysis revealed that this copolymer had vinyltriynepropoxysilane units.
It was confirmed that 99.5 moles of vinyl acetate units were heard at 0.5 moles. While stirring 100 parts of a methanol solution of this copolymer at 40°C, 2.77 parts of a 10-th methanol solution of sodium hydroxide (alkali molar ratio 0.017) was added to carry out a saponification reaction. The resulting white gel was completely ground, washed with methanol, and dried to give modified P.
Got a VA. The obtained modified PVA was soluble in water, and analysis in the same manner as in Example 1 revealed that it was bonded to the impropoxyl group and contained 0.4 moles of silyl group (as a vinylsilane unit).Hydrolysis of the isopropoxyl group Freshness: 20 moles Saponification degree of polyvinyl acetate units: 99.0 moles Viscosity of a 4% aqueous solution at 20°C: 29.5 Cp.

This 10% aqueous solution of modified PVA showed no change in viscosity even after being left at 30° C. for one week. This aqueous solution was cast onto a polyethylene film and dried at room temperature for 3 days to form a film.The film was then immersed in a 2N sulfuric acid bath and immersed in boiling water. It was found that it does not dissolve in water and has extremely high water resistance.

Example 3 2700 parts of vinyl acetate and 600 parts of methanol were placed in a reaction vessel equipped with a stirrer, thermometer, dropping funnel and reflux condenser.
After charging 3.7 parts of 3-acrylamide-propyltriisopropoxysilane and purging the system with gold nitrogen while stirring, the internal temperature was raised to 60'C''.
200 parts of a methanol solution containing 1.89 parts of '-azobisisobutyronitrile was added to initiate polymerization. At the start of polymerization, a methanol solution containing 25.4 parts of 3-acrylamidopropyltriisopropoxysilane was prepared at 74.
Polymerization was continued for 3 hours while dropping 6 parts into the system. The solid content concentration in the system at the time of termination of polymerization was 35%. After expelling unreacted vinyl acetate monomer by introducing methanol vapor, a 35% metall solution of the copolymer was obtained. This copolymer contains 0.5 mole of 3-acrylamitopropyltriisopropoxysilane units and 9 vinyl acetate units.
It was confirmed by nuclear magnetic resonance analysis that it contained 95 moles. 100 parts of a methanol solution of this copolymer was heated at 40°C.
While stirring, the entire methanol solution containing 1 mol of sodium hydroxide per vinyl acetate unit was added to carry out a saponification reaction. The obtained white gel was crushed,
After thorough washing with methanol to remove the unresolved 3-acrylamidoprobyltrimethoxysilane, the modified PVA was obtained by drying. Resonance analysis revealed that the silyl group unit bonded to the isopropoxyl group was 0.
4 mole split, hydrolyzed layer of isopropoxyl group 20 mole%
It was confirmed that the degree of saponification of vinyl acetate units was 88 moles. 1: The viscosity of a 4% aqueous solution of octopus at 20°C was 26 cp.

This 10% aqueous solution of modified PVA showed no change in viscosity even after being left at 30° C. for one week. This aqueous solution was cast onto a polyethylene film, dried at room temperature for 3 days to form a film, and after fC, the film was immersed in a 1/2 quart sulfuric acid bath and then immersed in boiling water. Does not dissolve in boiling water,
It was found that the water resistance was extremely high.

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

Claims (1)

[Claims] (1) Vinyl ester and the general formula (where Hl, R5 is a hydrogen atom or a methyl group,
R2, R3, R4 are the same or different lower alkyl groups, allyl groups, lower alkyl groups linked to allyl groups, A
is an olefinic compound having a silyl group bonded to a secondary alkoxyl group coated with a divalent organic residue which may be attached to a group containing oxygen or hydrogen, and n representing 0 to 2, respectively. A modified polyvinyl alcohol having a silyl group bonded to an alkoxyl group, which is characterized by copolymerizing an unsaturated monomer with a radical polymerization initiator and saponifying the resulting copolymer. Manufacturing method. (2) The method for producing modified polyvinyl alcohol according to claim 1, wherein the olefinically unsaturated monomer having a silyl group represented by general formula (1) is vinyltriisoproboxysilane. (8) A method for producing modified polyvinyl alcohol according to claim 1, wherein the polyvinyl alcohol is saponified in the presence of an alkali. (4) The method for producing modified polyvinyl alcohol according to claim 3, wherein the copolymer is saponified by the presence of an alkali of 0.03 to 0.001 (molar ratio) to all monomer units in the copolymer. .