JPH0237921B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for emulsion polymerization of olefinically unsaturated compounds, and more specifically, when emulsion polymerizing olefinically unsaturated compounds in an aqueous medium, modified polyvinyl alcohol containing silicon in the molecule is used as an emulsion stabilizer. This invention relates to a method for emulsion polymerization of olefinically unsaturated compounds. In emulsion polymerization of olefinic unsaturated compounds, especially vinyl acetate, it has been known to use polyvinyl alcohol (hereinafter abbreviated as PVA) as an emulsion stabilizer. However, the emulsion obtained using conventional PVA is
For example, when partially saponified PVA is used, the water resistance of the emulsion is low, and when completely saponified PVA is used, the emulsion has poor stability. Furthermore, it has the disadvantage of poor adhesion to inorganic materials such as concrete, glass, and clay minerals. Because of its low viscosity, it has the disadvantage that it cannot fully satisfy the required performance in fields that require water resistance or in fields where inorganic materials are often used. As a result of intensive research aimed at overcoming the above-mentioned drawbacks, the present inventors have found that when emulsion polymerizing an olefinically unsaturated compound, particularly vinyl acetate, or a mixture of olefinically unsaturated compounds mainly consisting of vinyl acetate, in an aqueous medium, the molecular Modification containing silicon within
When using PVA as a dispersion stabilizer, the usual
We have discovered that it is possible to produce emulsions with high stability, good water resistance, and excellent adhesion to organic and inorganic adherends by using a formulation similar to that used when PVA is used as an emulsion stabilizer, and have developed the present invention. It was completed. The modified PVA containing silicon in the molecule used in the present invention can be produced, for example, by the following method. A method of introducing silicon into PVA or modified polyvinyl acetate containing a carboxyl group or a hydroxyl group by post-modification using a silylating agent, and saponification of a copolymer of a vinyl ester and a silicon-containing olefinic unsaturated monomer. Examples include methods to do so. In the method of post-modifying PVA or modified polyvinyl acetate using a silylating agent, for example,
The silylating agent is dissolved in an organic solvent that does not react with the silylating agent, such as benzene, toluene, xylene, hexane, heptane, ether, or acetone, and powdered PVA or the modified polyvinyl acetate is suspended in the solution with stirring. The vinyl acetate unit is saponified by making the silylating agent cloudy and reacting the silylating agent with PVA or the above-mentioned modified polyvinyl acetate at a temperature ranging from room temperature to the boiling point of the silylating agent, or further using an alkali catalyst etc. Thus, silicon-containing modified PVA can be obtained. Examples of silylating agents used in such post-modification include organohalogensilanes such as trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, vinyltrichlorosilane, diphenyldichlorosilane, and triethylfluorosilane, and trimethylacetoxysilane. , organosilicon esters such as dimethyldiacetoxysilane, organoalkoxysilanes such as trimethylmethoxysilane and dimethyldimethoxysilane, organosilanols such as trimethylsilanol and diethylsilanediol, aminoalkylsilanes such as N-aminoethylaminopropyltrimethoxysilane, Organosilicon isocyanates such as trimethyl silicon isocyanate and the like can be mentioned. The rate of introduction of the silylating agent, that is, the rate of modification, can be arbitrarily adjusted by adjusting the amount of the silylating agent used and the reaction time. Further, the degree of polymerization and saponification of the obtained silicon-containing modified PVA can be arbitrarily adjusted by adjusting the degree of polymerization and saponification of the PVA used or the degree of polymerization and saponification of the modified polyvinyl acetate. In addition, in a method of saponifying a copolymer of a vinyl ester and a silicon-containing olefinic unsaturated monomer, for example, the vinyl ester and the silicon-containing olefinic unsaturated monomer are mixed in alcohol using a radical initiator. Silicon-containing modified PVA can be obtained by copolymerizing the copolymer and then saponifying the copolymer by adding an alkali or acid catalyst to an alcohol solution of the copolymer. Vinyl esters used in such a method include vinyl acetate, vinyl propionate, vinyl formate, etc., but vinyl acetate is preferred from an economic standpoint. On the other hand, examples of the silicon-containing olefinic unsaturated monomer used in such a method include vinylsilane represented by the following formula () or (meth)acrylamido-alkylsilane represented by (). (Here, n is 0 to 4, m is 0 to 2, R ¹ is hydrogen,
Halogen, lower alkyl group, allyl group, or lower alkyl group having an allyl group, R ² is an alkoxyl group, an acyloxyl group (here, the alkoxyl group or acyloxyl group may have a substituent containing oxygen or nitrogen) or a hydroxyl group, R ³ is hydrogen or a methyl group, R ⁴ is a lower alkyl group, R ⁵ is an alkylene group, or a divalent organic residue in which chain carbon atoms are bonded to each other via oxygen or nitrogen). Specific examples of the vinylsilane represented by the formula () include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris-(β-methoxyethoxy)silane, vinyltriacetoxysilane, allyltrimethoxysilane, allyltriacetoxysilane, vinyl Examples include methyldimethoxysilane, vinyldimethylmethoxysilane, vinylmethyldiethoxysilane, vinyldimethylethoxysilane, vinylmethyldiacetoxysilane, vinyldimethylacetoxysilane, vinyldimethylsilanol, vinylisobutyldimethoxysilane, and vinylmonochlorodimethoxysilane. Specific examples of the (meth)acrylamide-alkylsilane represented by the formula () include 3-(meth)acrylamide-propyltrimethoxysilane. 3-(meth)acrylamide-propyltriethoxysilane 3-(meth)acrylamide-propyltri(β-methoxyethoxy)silane 3-(meth)acrylamido-propyltri(N-methylaminoethoxy)silane 2-(meth)acrylamide-ethyltrimethoxysilane 1-(meth)acrylamide-methyltrimethoxysilane 2-(meth)acrylamido-2-methylpropyltrimethoxysilane 2-(meth)acrylamide-isopropyltrimethoxysilane (Meta) such as (R represents hydrogen or methyl group)
Acrylamide-linear or branched alkyltrialkoxysilane, N-(2-(meth)acrylamide-ethyl)-
Aminopropyltrimethoxysilane CH ₂ = CR・CONH−CH ₂ CH ₂ NH(CH ₂ ) ₃ Si
(OCH ₃ ) ₃ (3-(meth)acrylamidopropyl)-oxypropyltrimethoxysilane CH ₂ =CR・CONH−(CH ₂ ) ₃ −O−(CH ₂ ) ₃ Si
(Meta) such as (OCH ₃ ) ₃ (R represents hydrogen or methyl group)
Acrylamide-nitrogen-containing or oxygen-containing alkyltrialkoxysilane, 3-(meth)acrylamide-propyltriacetoxysilane _CH2 =CR・CONH( _CH2 ) ₃ -Si( _OCOCH3 ) _32- (meth)acrylamide-ethyltri Acetoxysilane CH ₂ = CR・CONH (CH ₂ ) ₂ Si (OCOCH ₃ ) ₃ 4-(meth)acrylamide-butyltriacetoxysilane CH ₂ = CR・CONH (CH ₂ ) ₄ Si (OCOCH ₃ ) ₃ 3-( meth)acrylamido-propyltripropionyloxysilane CH ₂ = CR・CONH(CH ₂ ) ₃ Si(OCOCH ₂ CH ₃ ) ₃ 2-(meth)acrylamido-2-methylpropyltriacetoxysilane N-(2-(meth)acrylamido-ethyl)-
Aminopropyltriacetoxysilane CH ₂ = CR・CONH−CH ₂ CH ₂ NH(CH ₂ ) ₃ Si
(OCOCH ₃ ) ₃ (R represents hydrogen or methyl group), acrylamide-alkyltriacyloxysilane, 3-(meth)acrylamido-propylisobutyldimethoxysilane 2-(meth)acrylamide-ethyldimethylmethoxysilane 3-(meth)acrylamide-propyloctyldiacetoxysilane 1-(meth)acrylamide-methylphenyldiacetoxysilane 3-(meth)acrylamide-propylbenzyldiethoxysilane 2-(meth)acrylamido-2-methylpropyl monochlorodimethoxysilane 2-(meth)acrylamido-2-methylpropylhydrodiene dimethoxysilane (Meta) such as (R represents hydrogen or methyl group)
Acrylamide-alkyl di- or monoalkoxy or di- or monoacyloxysilane, 3-(N-methyl-(meth)acrylamide)-
Propyltrimethoxysilane 2-(N-ethyl-(meth)acrylamide)-
Ethyltriacetoxysilane Examples include (N-alkyl-(meth)acrylamido-alkyltrialkoxy or triacyloxysilane such as (R represents hydrogen or a methyl group). In the above-mentioned method, vinyl ester and silicon-containing olefinic unsaturated monomer In addition to the above two components, other unsaturated monomers that can be copolymerized with these monomers, such as styrene, alkyl vinyl ether, vinyl versatate, (meth)acrylamide, etc. ethylene,
Olefins such as propylene, α-hexene, α-octene, unsaturated acids such as (meth)acrylic acid, crotonic acid, (anhydrous) maleic acid, fumaric acid, itaconic acid, and their alkyl esters and alkali salts,
Sulfonic acid-containing monomers such as 2-acrylamide-2-methylpropanesulfonic acid and their alkali salts, trimethyl-3-(1-acrylamide-1,
1-dimethylpropyl) ammonium chloride,
Trimethyl-3-(1-acrylamidopropyl)
It is also possible to include cationic monomers such as ammonium chloride, 1-vinyl-2-methylimidazole, and quaternized products thereof. The silicon content in the modified PVA containing silicon in the molecule used in the present invention, the degree of saponification or degree of polymerization of the vinyl ester unit are appropriately selected depending on the purpose, and are not particularly limited. Proper combinations of these three elements are important in producing emulsions. For many purposes, the amount of silicon-containing groups (as copolymerized units or monomeric units post-modified by silylating agents) is between 0.01 and 5 mol%, and the degree of saponification between 60 and 100 mol%. ,
The degree of polymerization is selected from the range of 100 to 3000. degeneration
The amount of PVA to be used is appropriately selected from the range of 0.1 to 20 parts by weight based on 100 parts by weight of the olefinic unsaturated compound. The olefinic unsaturated compounds used in the present invention include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl versatate which is a higher fatty acid vinyl ester, ethyl (meth)acrylate, ethyl (meth)acrylate, ( (Meth)acrylic acid esters such as butyl meth)acrylate and octyl (meth)acrylate, or vinyl chloride, vinylidene chloride, (meth)acrylonitrile, styrene, ethylene, propylene, (meth)acrylamide, N-methylol-
(meth)acrylamide, maleic acid diester,
Examples include fumaric acid diester, itaconic acid diester, butadiene, and isoprene, and any of them may be used alone or as a mixture thereof. Among the methods described above, the method of the present invention includes homopolymerization of vinyl acetate or copolymerization with monomers containing vinyl acetate, such as vinyl acetate-ethylene copolymerization, vinyl acetate-(meth)acrylate copolymerization,
It exhibits particularly excellent emulsion stability for polymerization systems such as vinyl acetate-diester maleate copolymerization, vinyl acetate-higher fatty acid vinyl ester copolymerization, and vinyl acetate-vinyl chloride copolymerization, and it also shows excellent emulsion stability for vinyl chloride homopolymerization and vinyl chloride homopolymerization. It can be preferably applied to polymerization systems such as single or mutual copolymerization of (meth)acrylic acid esters since it exhibits excellent emulsion stability. When carrying out emulsion polymerization of olefinic unsaturated compounds, the above-mentioned olefinic unsaturated compounds are added temporarily or continuously in the presence of water, a polymerization initiator, and modified PVA containing silicon in the molecule. Any conventional emulsion polymerization method such as heating and stirring can be carried out. At this time, other known emulsion stabilizers such as ordinary unmodified PVA, nonionic surfactants, etc. are added to the modified PVA containing silicon in the molecule.
Anionic surfactants, cationic surfactants, cellulose derivatives (carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, etc.), etc. can also be used in combination as appropriate.
In addition, various other additives, regulators, etc. used in ordinary emulsion polymerization can also be used as appropriate. Examples of emulsion polymerization initiators include initiators commonly used in emulsion polymerization, such as hydrogen peroxide, ammonium persulfate, tertiary hydroperoxide, and other known peroxides, or these together with sodium bisulfite, sodium pyrosulfite, and formaldehyde. Known redox systems in combination with reducing agents such as sodium sulfoxylate are employed. These polymerization initiators are used in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the olefinically unsaturated compound. The temperature when carrying out emulsion polymerization is 30 to 100
C., preferably 40 to 90.degree. C. may be employed. The emulsion obtained in the present invention is characterized by high adhesive strength and excellent water resistance. The reason for this performance is the modified emulsion stabilizer that contains silicon in the molecule.
This is thought to be based on the use of PVA.
In other words, the silicon atoms or silanol groups in modified PVA are highly reactive, and when applied to an adherend to form a film, they react with the adherend to form chemical bonds, and the silanol groups in modified PVA also react with each other to form a chemical bond. This is thought to be due to the reaction and formation of a crosslinked product. As mentioned above, the emulsion obtained in the present invention has high adhesive strength and excellent water resistance.
Its range of applications is wide: paper, wood, plastic,
organic and inorganic fibers, metals, glasses, clay minerals,
Adhesives, binders, additives for concrete, etc.
Used as a coating agent and paint. EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but these Examples are not intended to limit the present invention in any way. All parts and percentages are by weight unless otherwise specified. Example 1 A copolymer of vinyltrimethoxysilane and vinyl acetate was obtained by saponifying the copolymer, containing 0.25 mol% silicon as vinyl silane units, and having a saponification degree of vinyl acetate units of 87.5 mol%, a 4% aqueous solution. Silicon-containing modified material whose viscosity at 20°C (as measured by a Burckfield viscometer; the same applies hereinafter) is 30 centipoise (hereinafter centipoise is referred to as cp).
Emulsion polymerization of vinyl acetate was carried out as follows using PVA as an emulsion stabilizer. That is, the above modified PVA8 was placed in a separable flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer.
and 85 parts of water were added, stirred and heated to dissolve the modified PVA, and then cooled. 10 parts of vinyl acetate was added, and the internal temperature of the flask was raised to 60°C while stirring. While nitrogen gas was introduced into the flask to replace the inside of the system with nitrogen, an aqueous hydrogen peroxide solution and an aqueous sodium pyrosulfite solution were added as polymerization initiators to initiate polymerization. Initial polymerization was carried out for 30 minutes, and the remaining 90 parts of vinyl acetate was added dropwise over 3 hours, followed by aging at 70° C. for 1 hour and cooling. The resulting emulsion had a resin content of 50% and a viscosity of 54,000 cp at 30°C. Emulsion stability and water resistance are the first priority.
Shown in the table. Comparative Example 1 In place of the modified PVA of Example 1, a 4% aqueous solution with a degree of saponification of 88.0 mol% and a viscosity of 22.5 cp at 20°C was used.
An emulsion with a resin content of 49.0% and a viscosity of 20,000 cp at 30°C was obtained in the same manner as in Example 1 except that PVA was used. The stability and water resistance of the emulsion are also shown in Table 1. Comparative Example 2 In place of the modified PVA of Example 1, a 4% aqueous solution with a degree of saponification of 98.5 mol% and a viscosity of 29 cp at 20°C was used.
An emulsion with a resin content of 48.5% and a viscosity of 6500 cp at 30°C was obtained in the same manner as in Example 1 except that PVA was used. The stability and water resistance of the emulsion are also shown in Table 1.

[Table] Example 2 A copolymer of vinyltriacetoxysilane and vinyl acetate was saponified, containing 0.3 mol% silicon as vinyl silane units, and having a degree of saponification of vinyl acetate units of 91 mol%, 4 Emulsion polymerization of vinyl acetate was carried out as follows using silicon-containing modified PVA having a viscosity of 27 cp at 20°C in an aqueous solution as an emulsion stabilizer. That is, the above modification was carried out in a separable flask equipped with a stirrer, a reflux condenser, a dropping funnel, and a thermometer.
Add 8 parts of PVA and 92 parts of water, stir, heat up and denature.
The PVA was dissolved and then cooled. After adding and dissolving 0.185 parts of potassium persulfate, 18.5 parts of vinyl acetate
Nitrogen gas was introduced into the flask while stirring, and the internal temperature was brought to 64~64°C while replacing the system with nitrogen.
Polymerization was started by raising the temperature to 65°C. After initial polymerization for 20 minutes, 74 parts of vinyl acetate was added dropwise over 2.5 hours, and then aged at 70°C for 1 hour,
Cooled. The resulting emulsion has a resin content of 45%.
The viscosity at 30°C was 35,000 cp. After adding 10 parts of dibutyl phthalate as a plasticizer to 100 parts of this emulsion, apply it on each of the glass plate, mortar, or plywood so that the film after drying becomes 200μ (micrometer).
A cotton cloth was placed as a reinforcing agent and air-dried for 3 days to form a film. Cut this film into a width of 1 with a cutter knife.
Make a cut in cm, temperature 20℃, relative humidity 65%RH
After controlling the humidity in a constant temperature room for 3 days, and then further heating at 20℃
After immersed in water for 3 days, autograph
Peel strength was measured at a 90° angle. The results are shown in Table 2. Example 3 A copolymer of 3-acrylamide-propyltriethoxysilane and vinyl acetate was obtained by saponifying the copolymer, containing 0.2 mol% silicon as acrylamide-silane units, and having a degree of saponification of vinyl acetate units of 99 mol. %, the viscosity of a 4% aqueous solution at 20℃ is
The procedure was the same as in Example 2, except that a silicon-containing modified PVA having a 27 cp was used in place of the modified PVA of Example 2, with a resin content of 43.7% and a viscosity of 25,000 cp at 30°C.
An emulsion was obtained. Using this emulsion, the adhesive strength and water-resistant adhesive strength to glass, mortar, and plywood were measured in the same manner as in Example 2. The results are also shown in Table 2. Example 4 A copolymer of 2-acrylamide-2-methylpropyltriethoxysilane and vinyl acetate was obtained by saponifying the copolymer, containing 0.4 mol% of silicon as an acrylamide-silane unit, and having a saponification degree of vinyl acetate units. The procedure was repeated in the same manner as in Example 2, except that silicon-containing modified PVA having a viscosity of 25 cp at 20°C in an 89 mol%, 4% aqueous solution was used in place of the modified PVA in Example 2. An emulsion with a viscosity of 36000 cp was obtained. Glass was prepared using this emulsion in the same manner as in Example 2.
Adhesion to mortar and plywood was measured.
The results are also shown in Table 2. Comparative Example 2 In place of the modified PVA of Example 2, a 4% aqueous solution with a degree of saponification of 88 mol% and a viscosity of 22.5 cp at 20°C was used.
An emulsion with a resin content of 45.5% and a viscosity of 15,000 cp at 30° C. was obtained in the same manner as in Example 2 except that PVA was used. Example 2 using this emulsion
Adhesion strength to glass, mortar, and plywood was measured in the same manner as above. The results are also shown in Table 2.

[Table] Example 5 A copolymer of vinyldimethylethoxysilane and vinyl acetate was obtained by saponifying the copolymer, containing 1 mol% of silicon as vinyl silane units, and the saponification degree of vinyl acetate units was 87.5 mol% and 4%. An ethylene-vinyl acetate emulsion copolymerization method was carried out as follows using silicon-containing modified PVA whose aqueous solution has a viscosity of 7.5 cp at 20°C as an emulsion stabilizer. That is, 6 parts of the modified PVA and distilled water are placed in a pressure-resistant reaction tank equipped with a stirrer, a temperature detection end, and a liquid charging device.
100 parts of the modified PVA was added and stirred to raise the temperature to dissolve the above modified PVA. After cooling, 120 parts of vinyl acetate was added to the system with stirring, and ethylene gas was further introduced to adjust the system pressure to 45 Kg/cm ² while the temperature inside the system was raised to 60°C. A hydrogen peroxide aqueous solution and a sodium pyrosulfite aqueous solution were added at a temperature of 60°C, and emulsion polymerization was carried out for 3 hours. After the polymerization was completed, the pH was adjusted to 6.0 with an ammonia aqueous solution. The obtained ethylene-vinyl acetate copolymer emulsion contained 45.2 mol% of ethylene units and resin content.
49.5%, and the viscosity at 30°C was 85 cp. The stability of the emulsion and the adhesion to glass and mortar were measured in the same manner as in Example 1 or Example 2. The results are shown in Table 3. Comparative Example 3 In place of the modified PVA of Example 5, a 4% aqueous solution with a degree of saponification of 88 mol% and a viscosity of 8.0 cp at 20°C was used.
An emulsion with a resin content of 50% and a viscosity of 79 cp at 30° C. was obtained in the same manner as in Example 5 except that PVA was used. The stability and adhesive strength of this emulsion were measured in the same manner as in Example 5. The results are also shown in Table 3.

[Table] Example 6 Obtained by saponifying a copolymer of vinyltriethoxysilane and vinyl acetate, containing 0.25 mol% silicon as vinyl silane units, saponification degree of vinyl acetate units 87 mol%, 4% Copolymerization of vinyl acetate-ethyl acrylate system was carried out as follows using silicon-containing modified PVA having a viscosity of 6.5 cp at 20°C as an aqueous solution as an emulsion stabilizer. That is, 10% of the above modified PVA was placed in a reaction vessel equipped with a stirrer, a thermometer, a dropping funnel and a reflux condenser.
After preparing 450 parts of aqueous solution, 10 parts of ethyl acrylate and 50 parts of vinyl acetate and uniformly emulsifying it, 6%
41 parts of ammonium persulfate and 60 parts of 10% sodium bisulfite were added, and the temperature in the system was raised to 60°C to initiate polymerization. While continuing the polymerization at a temperature of 60° C., a mixture of 90 parts of ethyl acrylate and 450 parts of vinyl acetate and 80 parts of a 2% ammonium persulfate aqueous solution were added dropwise to carry out emulsion polymerization for 3 hours. After completion of the dropwise addition, the temperature was raised to 70°C and aged for 30 minutes, then cooled to room temperature and the pH was adjusted to 5.0 with a 10% ammonia aqueous solution. The resulting copolymer emulsion has a resin content of
52%, and the viscosity at 30°C was 130 cp. This emulsion showed no change in system even after being left at 30°C for 3 months and remained stable. In addition, the normal adhesive strength and water resistant adhesive strength to mortar are respectively
They were 5.7Kg/cm and 5.0Kg/cm.

Claims (1)

[Claims] 1. A method for emulsion polymerization of an olefinic unsaturated compound, which comprises using modified polyvinyl alcohol containing silicon in the molecule as an emulsion stabilizer when the olefinic unsaturated compound is emulsion polymerized in an aqueous medium.