JP2001139612A - Dispersant for emulsion polymerization and its use - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dispersant for emulsion polymerization which dispersant enables one to obtain a vinyl resin emulsion which is excellent in properties such as flowability and the like, low-temperature stability, stock stability, waterproof adhesiveness and the like. SOLUTION: This dispersant for emulsion polymerization contains a polyvinyl alcohol resin containing an acetoacetic ester group and a polyvinyl alcohol having a degree of iodine color identification of not less than 0.05.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an acetoacetic ester group-containing polyvinyl alcohol-based resin (hereinafter referred to as AA
VA) and a vinyl resin emulsion using the same as a dispersant for emulsion polymerization comprising
More specifically, the present invention relates to a dispersant for emulsion polymerization useful for obtaining a vinyl resin emulsion excellent in flow stability, low temperature stability, storage stability, water resistance and the like, and a vinyl resin emulsion using the same.

[0002]

2. Description of the Related Art As a dispersant for emulsion polymerization of a vinyl resin emulsion such as a polyvinyl acetate emulsion,
Conventionally, polyvinyl alcohol-based resins (hereinafter abbreviated as PVA) have been known, and in recent years, AA-PVA modified with acetoacetate has been used for the purpose of improving the water-resistant adhesive strength of a polyvinyl acetate emulsion. Have been. The present applicant also used such AA-PVA to coexist with a polyvalent metal salt of an organic acid having a pka ≧ 4,
H2.5-6.5 emulsion polymerization (JP-A-1-20
No. 4901) and a method of emulsion polymerization in the presence of an acid sulfite (JP-A-7-138305). Further, an emulsion dispersion stabilizer for AA-PVA containing a specific amount of acetate and acetic acid ( JP-A-9-31112) and an emulsion dispersion stabilizer of AA-PVA containing a specific amount of iron (JP-A-9-77948).

[0003]

However, in any of the above-mentioned methods, although the water-resistant adhesive strength of the obtained emulsion is improved, the heat-resistant water adhesive strength is not always sufficient. There is a need for a dispersant for emulsion polymerization which is useful for obtaining a vinyl resin emulsion having further improved flow stability, low temperature stability, storage stability and the like.

[0004]

The present inventor has conducted intensive studies in view of the present situation, and has found that AA-PVA (A)
The present inventors have found that a dispersant for emulsion polymerization containing PVA (B) having an iodine coloration of 0.05 or more meets the above-mentioned object, thereby completing the present invention. In the present invention, when the degree of saponification (SV mol%) and the degree of iodine coloration (I) of the PVA (B) satisfy the condition of the following formula (1), the effect of the present invention is more remarkable. It was also found that it can be obtained. 4.26 ≦ I + 0.047 × SV ≦ 4.73 (1) The iodine color degree refers to 10 ml of a sample (PVA) aqueous solution adjusted to 0.1% by weight, 6 ml of pure water, 1 / 10
4 ml of a 00 [N] iodine solution was mixed, adjusted to 25 ° C., allowed to stand for 20 minutes, and then measured for absorbance at a wavelength of 490 nm and a slit width of 1 mm.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The AA-PVA (A) used in the present invention is obtained by reacting PVA with diketene or reacting PVA with acetoacetate and transesterifying to introduce an acetoacetate group into PVA, as described later. As such PVA, generally, a saponified product or a derivative thereof obtained by saponifying a lower alcohol solution of polyvinyl acetate with a saponification catalyst such as an alkali or an acid is used. It is also possible to use a saponified copolymer of a monomer having a vinyl acetate and the like,
Examples of the monomer include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, and α-octadecene; acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, and itaconic acid. Unsaturated acids or their salts or mono- or dialkyl esters, etc., acrylonitrile, nitriles such as methacrylonitrile, amides such as acrylamide and methacrylamide, ethylene sulfonic acid, allyl sulfonic acid, olefin sulfonic acid such as methallyl sulfonic acid and the like salt.

Alkyl vinyl ethers, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethyldiallylammonium chloride, dimethylallylvinylketone, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, polyoxyethylene (meth) allyl ether, Polyoxyalkylene (meth) allyl ether such as polyoxypropylene (meth) allyl ether, polyoxyethylene (meth) acrylate, polyoxyalkylene (meth) acrylate such as polyoxypropylene (meth) acrylate, polyoxyethylene (meth) Acrylamide, polyoxyalkylene (meth) acrylamide such as polyoxypropylene (meth) acrylamide,
Polyoxyethylene (1- (meth) acrylamide-
1,1-dimethylpropyl) ester, polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene vinylamine and the like.

[0007] P as a raw material of such AA-PVA (A)
Although the degree of saponification of VA is not particularly limited, it is 85 mol% or more (further 88 to 99.9 mol%, particularly 89 to 99. mol%).
9 mol%), and the degree of saponification is 8
If the amount is less than 5 mol%, a cloud point appears during emulsion polymerization, which is not preferable. The average degree of polymerization of the PVA is not particularly limited, but is preferably 100 to 3000 (more preferably 300 to 2400, particularly 500 to 1800). If the average degree of polymerization is less than 100, the protective colloid becomes insufficient and emulsion polymerization is carried out. Occasionally, emulsion particles will aggregate, and conversely, 30
If it exceeds 00, the viscosity of the emulsion becomes too high, which is not preferable.

To obtain AA-PVA (A), a method of reacting PVA with diketene as described above, a method of transesterifying PVA with acetoacetate, a method of copolymerizing vinyl acetate and vinyl acetoacetate, etc. However, it is preferable to produce PVA (powder) with diketene from the viewpoint that the production process is simple and a high-quality AA-PVA can be obtained. As a method of reacting PVA with diketene, PVA may be directly reacted with gaseous or liquid diketene, or the organic acid may be reacted with diketene.
A method of spraying and reacting liquid or gaseous diketene in an inert gas atmosphere after adsorbing and absorbing in advance in VA, or spraying and reacting a mixture of an organic acid and liquid diketene on PVA is used. As a reaction device for performing the above reaction, a device capable of heating and having a stirrer is sufficient. For example, a kneader, a Henschel mixer, a ribbon blender, various other blenders, and a stirring and drying device can be used.

The AA-PVA (A) thus obtained preferably has an acetoacetate group content of 0.5 to 5 mol% (more preferably 1 to 5 mol%, especially 2 to 4 mol%). If the content is less than 0.5 mol%, the resulting emulsion will have insufficient hot water adhesion, and conversely 5 mol%
Exceeding the viscosity is not preferred because the viscosity stability of the emulsion decreases.

For the PVA (B) having iodine coloration of 0.05 or more used together with the AA-PVA (A), the same PVA as described above before the introduction of the acetoacetate group is used. However, in the present invention, the iodine coloration degree of the PVA (B) needs to be 0.05 or more (furthermore, 0.10 or more, particularly 0.15 or more). In obtaining PVA of chromaticity, there is no particular limitation. Usually, during the production of PVA, the iodine coloration decreases with the saponification treatment time, so by controlling such saponification time,
What is necessary is just to adjust the iodine coloration degree, and furthermore, 32c.gse
By performing saponification using a solvent of su or less, it is possible to increase iodine coloration.

The degree of saponification of PVA (B) is not particularly limited, but is preferably 78 mol% or more (more preferably 80 to 98 mol%, particularly 85 to 95 mol%), and the saponification degree is 78 mol%. If it is less than 1, the cloud point appears during emulsion polymerization, and the polymerization stability is undesirably reduced. Further, the average degree of polymerization of PVA is 100 to 3000 (further, 300 to 240
0, particularly preferably 500 to 2000). When the average degree of polymerization is less than 100, the protective colloid power of the emulsion during emulsion polymerization is insufficient and the polymerization stability is lowered.
If it exceeds 000, the viscosity of the obtained emulsion tends to be too high, which is not preferable.

Further, in the present invention, such PVA
(B) Saponification degree (SV mol%) and iodine coloration degree (I)
Is the following formula (1) (furthermore, formula (1 ′), particularly (1 ″))
When the condition of the formula) is satisfied, the effect of the present invention is particularly remarkably obtained. 4.26 ≦ I + 0.047 × SV ≦ 4.73 (1) 4.28 ≦ I + 0.047 × SV ≦ 4.73 (1 ′) 4.30 ≦ I + 0.047 × SV ≦ 4 .73 (1 ″) In the expression (1), when the value of I + 0.0047 × SV is less than 4.26, the effect of the present invention cannot be sufficiently satisfied. If it exceeds 73, industrial production becomes difficult, which is not preferable.

In order to obtain PVA (B) satisfying such conditions, there is no particular limitation.
In the saponification step in the production of A (B), the dielectric constant is 32
This can be achieved by performing alkali saponification in the presence of a solvent of cgsesu or less. The dielectric constant is 32c.gsesu
The following solvents include methanol (31.2 c.gse
su), methyl acetate / methanol = 1/3 (27.1 c.
gsesu), methyl acetate / methanol = 1/1 (2
1.0 c.gsesu), methyl acetate / methanol = 3 /
1 (13.9 c. Gsesu), methyl acetate (7.03 c.
gsesu), isopropyl acetate (6.3 c.gs)
esu), trichlorethylene (3.42c.gses)
u.), xylene (2.37 c.gsesu), toluene (2.38 c.gsesu), benzene (2.28 c.gs)
esu), acetone (21.4 c. gsesu) and the like, and a mixed solvent of methyl acetate / methanol is preferably used. The temperature and resin content during saponification are
Although not particularly limited, the temperature is preferably slightly lower than the boiling point of the saponification solvent.
It is preferably set to 65 to 65% by weight (more preferably 40 to 50% by weight).

The dispersant for emulsion polymerization of the present invention contains (A) and (B) as described above. The content ratio is not particularly limited, but A / B (weight ratio) = 99. 9 /
0.01 to 50/50 (further 99/1 to 60/40,
In particular, the ratio is preferably 95/5 to 70/30). In such a weight ratio, when the content of (A) is excessive, the stability of the emulsion is reduced. The adhesive strength is undesirably reduced.

The thus-obtained dispersant for emulsion polymerization of the present invention is useful for obtaining a vinyl resin emulsion having excellent properties such as fluidity, and low temperature stability, shelf stability, water resistance and the like. The method of emulsion polymerization of unsaturated monomers which is useful and uses such a dispersant for emulsion polymerization will be specifically described. When performing the emulsion polymerization, an unsaturated monomer is added temporarily or continuously in the presence of the dispersant for emulsion polymerization of the present invention, water and a polymerization catalyst, and the emulsion is subjected to a usual emulsification polymerization such as heating and stirring. Legitimacy can be implemented. Such a dispersant for emulsion polymerization is added to an aqueous medium as a powder or as an aqueous solution. The amount used varies slightly depending on the required emulsion viscosity and the required resin content of the emulsion, but usually ranges from about 1 to 50% by weight, preferably about 2 to 20% by weight, based on the unsaturated monomer. It is preferably selected.

As the catalyst to be used, a water-soluble catalyst, particularly a radical generator, is preferably used. For example, potassium persulfate, ammonium persulfate and the like are used alone or in combination with sodium acid sulfite. Further, redox catalysts such as hydrogen peroxide-tartaric acid, hydrogen peroxide-iron salt, hydrogen peroxide-ascorbic acid-iron salt, hydrogen peroxide-Rongalit, and hydrogen peroxide-Rongalit-iron salt are used. A catalyst consisting of an organic peroxide and a redox-based catalyst such as Kayabutyl B manufactured by Kayaku Akzo Co., Ltd. and Kayabutyl A-50C manufactured by Kayaku Co., Ltd. is used. It is preferably used. If necessary, various surfactants (eg, anionic surfactants such as dodecylbenzenesulfonic acid and fatty acid salts, nonionic surfactants, etc.) or emulsifiers (eg, cellulose derivatives such as carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, etc.) Acrylic acid derivative, (anhydride) maleic acid-vinyl ether copolymer, (anhydride) maleic acid-vinyl acetate copolymer, vinyl acetate- (meth) allylsulfonic acid (salt) copolymer saponified product, etc.), as protective colloid Various known PVAs and PVA derivatives other than (A) and (B) can be used in combination as appropriate. Further, a plasticizer such as a phthalic acid ester and a phosphoric acid ester, and a pH adjuster such as sodium carbonate, sodium acetate and sodium phosphate may be used in combination.

Examples of the unsaturated monomers to be subjected to emulsion polymerization include ethylenically unsaturated monomers and butadiene monomers. Examples of the ethylenically unsaturated monomers include vinyl acetate and acrylic acid. Ester, methacrylic acid ester, vinyl chloride, vinylidene chloride, acrylonitrile, styrene and the like can be mentioned, and homopolymerization or copolymerization thereof is carried out, and a vinyl acetate monomer is preferably used. Further, when an acrylic monomer such as an acrylate or a methacrylate is homopolymerized or copolymerized, a remarkable effect that an emulsion having particularly good mechanical stability, storage stability, pigment miscibility and the like can be obtained. Therefore, it is suitably used for emulsion polymerization of an acrylic monomer.

As the butadiene monomer, butadiene-1,3,2-methylbutadiene, 1,3 or 2,
There are 3-dimethylbutadiene-1,3, 2-chlorobutadiene-1,3 and the like, which are used alone or as a mixture with an ethylenically unsaturated monomer. Among them, butadiene-
1,3 and styrene, butadiene-1,3 and styrene and (meth) acrylic acid, butadiene-1,3 and acrylonitrile, butadiene-1,3 and acrylonitrile and styrene, butadiene-1,3 and acrylonitrile and (meth) acryl It is also possible to carry out the polymerization using a combination of an acid, butadiene-1,3 and methyl methacrylate, or butadiene-1,3, methyl methacrylate and (meth) acrylic acid.

Although the emulsion using the dispersant for emulsion polymerization of the present invention has been described above, the vinyl resin emulsion using the dispersant for emulsion polymerization of the present invention has a characteristic property that the film formed has characteristic properties. Things. That is, when the storage elastic modulus of the film obtained from such a vinyl resin emulsion is in the range of 60 to 120 ° C., the following formula (2) is always satisfied, and when the value on the left side of the formula is 0.25 or less, However, the adhesive strength of hot water is insufficient and good physical properties as an adhesive cannot be obtained. E′2 / E′1> 0.25 (2) Here, E′1 is a film obtained from the above emulsion (after casting the emulsion on a PET film using an applicator, Storage elastic modulus (Pa) of a 10 μm thick film obtained by drying at a temperature 20 ° C. higher than the minimum film forming temperature of 4 hours for 4 hours.
And E′2 represents the storage elastic modulus (Pa) after the obtained film was immersed in boiling water for 4 hours and left at 23 ° C. for 24 hours. The storage elastic modulus referred to here is 110
Hz, which can be measured by a dynamic viscoelasticity measuring device.
Up to 120 ° C at a rate of 2 ° C / min,
E′1 and E ′ are the values obtained by continuously measuring with the measuring device.
The value of 2 is a value at the same temperature.

The vinyl resin emulsion of the present invention as described above can be used as an adhesive, a binder, a coating agent, etc., and is particularly useful as an adhesive. It is used at about 30 to 60%, the amount of additives in the solid content is about 1 to 30% by weight, and fillers, defoamers (or foaming agents), coloring agents, film-forming aids, antiseptic / insect repellents And additives such as a rust preventive are compounded and used for adhesives. Examples of the target adhesive (adherend) include wood, paper, plastics, and fibers. Particularly in adhesive applications, the emulsifying dispersant of the present invention can be used as it is as a one-part adhesive, and two-part types such as conventional aqueous polymer-isocyanate-based adhesives and melamine-formaldehyde-based adhesives can be used. It has a hot water adhesive strength equal to or higher than that of the adhesive, and can greatly improve workability and the like.

[0021]

The present invention will be described below in more detail with reference to examples. Unless otherwise noted, "%",
“Parts” indicate weight standards. Example 1 [Production of AA-PVA (A)] 0.3% sodium acetate
% PVA powder (degree of saponification: 99.6 mol%, average degree of polymerization: 1100; completely saponified to JIS K 6726)
200 parts were charged into a kneader, and 60 parts of acetic acid was added to the kneader to cause swelling.
After the temperature was raised to 65 ° C. while stirring at pm, 29 parts of diketene was added dropwise over 4 hours, and the mixture was further reacted for 30 minutes to give an AA-PVA containing 5.3 mol% of acetoacetate ester groups.
(A) was obtained.

[Production of PVA (B)] Methyl acetate was added to a methanol solution of polyvinyl acetate (average degree of polymerization: 1100) obtained by a conventional method, and polyvinyl acetate / methanol / methyl acetate = 34/59 / 7 (weight ratio) to obtain a polyvinyl acetate solution.
0 parts were charged into a kneader, and the liquid temperature was adjusted to 40 ° C.
When the liquid temperature reached 40 ° C., 3.2 ml of a methanol solution of sodium hydroxide (containing 2% as Na) was used as a catalyst.
The saponification was carried out for 2 hours. Then, after neutralizing with acetic acid to stop the saponification reaction, washing is repeated with methanol, and then drying is performed to obtain PVA having a saponification degree of 88.3 mol% (residual acetic acid groups of 11.7 mol%). Obtained. Note that P
The iodine coloration degree (I) of VA (B) was 0.158 as measured by the method described in the text, and the degree of saponification (S)
V mol%) is 88.3 mol%, and I + 0.0047 × S
V = 0.158 + 0.047 × 88.3 = 4.31 was achieved, thereby satisfying the expression (1) in the text.

The dispersant for emulsion polymerization of the present invention was obtained by mixing 80 parts of the AA-modified PVA (A) obtained above and 20 parts of PVA (B). Using the obtained dispersant for emulsion polymerization,
A vinyl acetate resin emulsion was prepared as described below, and the properties of the emulsion, low-temperature stability, storage stability, and water resistance were evaluated as described below.

(Production of vinyl acetate resin emulsion) In a separable flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, 60 parts of water, 4 parts of the dispersant for emulsion polymerization obtained above and a pH adjuster As sodium acetate 0.02
And 3.6 parts of a vinyl acetate monomer, and the temperature in the flask was raised to 60 ° C. while stirring. Meanwhile, while replacing the inside of the flask with nitrogen gas, 5 ml of a 1% aqueous solution of ammonium persulfate was added to initiate polymerization. Initial polymerization was carried out for 30 minutes, 32.4 parts of the remaining vinyl acetate monomer was added dropwise over 3 hours, and 5 ml of a 1% aqueous solution of ammonium persulfate was further divided into 4 portions every hour to carry out polymerization.

Thereafter, the mixture was aged at 75 ° C. for 1 hour and cooled, and the solid content was 39.6% and the viscosity was 38 Pa · sec (25
C)) to give an emulsion of vinyl acetate. When a film was prepared from the obtained emulsion and the storage elastic modulus was measured, the storage elastic modulus E′1 at each temperature was 7.2 × 10 ⁸ P
a (60 ° C.), 7.9 × 10 ⁷ Pa (80 ° C.), 1.2
× 10 ⁷ Pa (100 ° C.), 4.9 × 10 ⁶ Pa (120
° C) and soak the coating in boiling water for 4 hours to
Storage elastic modulus E′2 at each temperature after standing at 24 ° C. for 24 hours is:
5.2 × 10 ⁸ Pa (60 ° C.), 3.2 × 10 ⁷ Pa (8
0 ° C.), 8.4 × 10 ⁶ Pa (100 ° C.), 3.9 × 1
Was 0 ⁶ Pa (120 ℃). From these measurements,
When the value of E'2 / E'1 at each temperature was calculated, 0.72 (60 ° C), 0.40 (80 ° C), 0.7
0 (100 ° C.) and 0.79 (120 ° C.).

Incidentally, the storage elastic modulus was determined by "D
The measurement was performed under the following conditions using "VE RHEOSPECTORDVE-V4". Jig: tensile load: automatic static load Frequency: 110 Hz Heating rate: 2 ° C./min (room temperature to 120 ° C.) Displacement amplitude: 15 μm The obtained vinyl acetate emulsion was evaluated in the following manner.

(Properties of Emulsion) The state of the emulsion after production was visually observed and evaluated as follows. ○ --- Good fluidity, no coarse particles are observed. △ --- Good fluidity, but some coarse particles are observed. × --- Many coarse particles are observed, and aggregation of emulsion is observed. (Low-temperature stability) The emulsion after the production was allowed to stand at 0 ° C. for 5 days, returned to room temperature (25 ° C.), and examined for a change in viscosity, and evaluated as follows. ○---No increase in viscosity is observed at all----The increase in viscosity is within 1.8 times x---The increase in viscosity exceeds 1.8 times (standing stability)
C) and the number of days until the viscosity doubled was determined. (Heat-resistant water adhesion) After preparing a test piece in accordance with JIS K 6804, the adhesive strength (kg / cm ² ) was measured in accordance with the repeated boiling test in JIS K 6852.

Example 2 In [Production of PVA (B)] of Example 1, methyl acetate was added to a methanol solution of polyvinyl acetate (average degree of polymerization: 1100) obtained by a conventional method, and polyvinyl acetate / polyvinyl acetate was added. Methanol / methyl acetate = 34/63/3 (weight ratio)
And a saponification degree of 87.2 mol% (residual acetic acid group 1).
(2.8 mol%) of PVA (B). In addition, such PV
The iodine coloration degree (I) of A (B) was 0.184 as measured by the method described in the text, and the degree of saponification (SV
Mol%) is 87.2 mol%, and I + 0.0047 × SV
= 0.184 + 0.047 × 87.2 = 4.28, thereby satisfying the expression (1) in the text.

AA-PVA (A) 8 obtained in Example 1
0 parts and 20 parts of the above PVA (B) were blended to obtain a dispersant for emulsion polymerization of the present invention. Using the obtained dispersion for emulsion polymerization, in the same manner as in Example 1, a vinyl acetate resin emulsion (solid content: 39.9%, viscosity: 31 Pa · sec (2
5 ° C.) and evaluated similarly. Further, a film was prepared from the obtained emulsion, and the storage modulus was measured in the same manner as in Example 1. The storage modulus E′1 at each temperature was 7.2 × 10 ⁸ Pa (60 ° C.). , 7.9 × 10
⁷ Pa (80 ° C.), 1.3 × 10 ⁷ Pa (100 ° C.)
A ^{5.0 × 10 6 Pa (120 ℃} ), storage modulus E'2 at each temperature for 24 hours after leaving such film 4 hours with boiling water immersion to 23 ° C. is, 5.0 × 10 ⁸ Pa (60
° C), 3.1 × 10 ⁷ Pa (80 ° C.), 8.5 × 10 ⁶ P
a (100 ° C.) and 3.6 × 10 ⁶ Pa (120 ° C.). From these measured values, the value of E′2 / E′1 at each temperature was calculated to be 0.70 (60 ° C.),
0.39 (80 ° C), 0.65 (100 ° C), 0.72
(120 ° C.).

Example 3 In [Production of PVA (B)] in Example 1, a methanol solution of polyvinyl acetate (average degree of polymerization: 1100) obtained by a conventional method (vinyl acetate / methanol = 40/60).
(Weight ratio)) except that saponification degree 8
7.2 mol% (residual acetic acid group: 12.8 mol%) of PVA
(B) was obtained. Incidentally, the iodine coloration (I) of PVA (B) was measured by the method described in the text to find that it was 0.1.
110, the degree of saponification (SV mol%) was 88.3 mol%, and I + 0.0047 × SV = 0.110 + 0.04
7 × 88.3 = 4.26 was achieved, thereby satisfying the expression (1) in the text.

AA-PVA (A) 8 obtained in Example 1
0 parts and 20 parts of the above PVA (B) were blended to obtain a dispersant for emulsion polymerization of the present invention. Using the obtained dispersion for emulsion polymerization, in the same manner as in Example 1, a vinyl acetate resin emulsion (solid content: 39.8%, viscosity: 22 Pa · sec (2
5 ° C.) and evaluated similarly. Further, a film was prepared from the obtained emulsion, and the storage modulus was measured in the same manner as in Example 1. The storage modulus E′1 at each temperature was 7.1 × 10 ⁸ Pa (60 ° C.). , 7.6 × 10
⁷ Pa (80 ° C), 1.0 × 10 ⁷ Pa (100 ° C),
4.6 × a 10 ⁶ Pa (120 ℃), storage modulus E'2 at each temperature for 24 hours after being left at such film 4 hours immersion in boiling water to 23 ° C. is, 4.8 × 10 ⁸ Pa (60
℃), 2.8 × 10 ⁷ Pa (80 ° C.), 6.3 × 10 ⁶ P
a (100 ° C.) and 3.3 × 10 ⁶ Pa (120 ° C.). When the value of E′2 / E′1 at each temperature was calculated from these measured values, 0.68 (60 ° C.)
0.37 (80 ° C), 0.63 (100 ° C), 0.71
(120 ° C.).

Example 4 In Example 1, 70 parts of AA-PVA (A) and PVA
A (B) 30 parts is blended, the dispersant for emulsion polymerization of the present invention
Example 1 was obtained using the obtained dispersant for emulsion polymerization.
In the same manner as described above, vinyl acetate resin emulsion (solid content 3
9.8%, viscosity 29 Pa · sec (25 ° C)
And evaluated similarly. Also, the obtained emulsion
And a storage modulus was measured in the same manner as in Example 1.
As a result, the storage elastic modulus E′1 at each temperature was 7.0.
× 10⁸Pa (60 ° C.), 7.4 × 10⁷Pa (80
° C), 1.0 × 10⁷Pa (100 ° C.), 4.5 × 10⁶
Pa (120 ° C), and immerse the coating in boiling water for 4 hours
Storage elasticity at each temperature after storage at 23 ° C for 24 hours
The rate E′2 is 4.6 × 10⁸Pa (60 ° C), 2.5 x 1
0 ⁷Pa (80 ° C), 5.8 × 10⁶Pa (100 ° C),
3.0 × 10⁶Pa (120 ° C.). These measurements
From the constant value, the value of E'2 / E'1 at each temperature
When calculated, 0.66 (60 ° C.), 0.34 (80
° C), 0.58 (100 ° C), 0.66 (120 ° C)
there were.

Example 5 In Example 1, 90 parts of AA-PVA (A) and PVA
A (B) 10 parts is blended, the dispersant for emulsion polymerization of the present invention
Example 1 was obtained using the obtained dispersant for emulsion polymerization.
In the same manner as described above, vinyl acetate resin emulsion (solid content 4
0.0%, viscosity 18 Pa · sec (25 ° C)
And evaluated similarly. Also, the obtained emulsion
And a storage modulus was measured in the same manner as in Example 1.
As a result, the storage elastic modulus E′1 at each temperature was 7.3.
× 10⁸Pa (60 ° C.), 8.0 × 10⁷Pa (80
1.3 ° C)⁷Pa (100 ° C.), 4.9 × 10⁶
Pa (120 ° C), and immerse the coating in boiling water for 4 hours
Storage elasticity at each temperature after storage at 23 ° C for 24 hours
The rate E′2 is 5.0 × 10⁸Pa (60 ° C.), 3.0 × 1
0 ⁷Pa (80 ° C), 7.7 × 10⁶Pa (100 ° C),
3.3 × 10⁶Pa (120 ° C.). These measurements
From the constant value, the value of E'2 / E'1 at each temperature
When calculated, 0.68 (60 ° C.), 0.37 (80
° C), 0.59 (100 ° C), 0.68 (120 ° C)
there were.

Example 6 In Example 1 [Production of AA-PVA (A)], 200 parts of PVA powder containing 0.5% of sodium acetate (saponification degree 98.5 mol%, average polymerization degree 1200) Was charged in a kneader, swelled with 60 parts of acetic acid, heated to 60 ° C. while stirring at a rotation speed of 20 rpm, and 24 parts of diketene was added dropwise over 4 hours, and further reacted for 30 minutes. AA containing 4.5 mol% of acetate groups
A vinyl acetate resin was obtained in the same manner as in Example 1 by using the same procedure as in Example 1, except that the modified PVA (A) was obtained. Emulsion (solid content 39.5%, viscosity 37 Pa · sec (25
° C) and evaluated similarly. Further, a film was prepared from the obtained emulsion, and the storage modulus was measured in the same manner as in Example 1. As a result, the storage modulus E ′ at each temperature was measured.
1 is 7.3 × 10 ⁸ Pa (60 ° C.), 7.9 × 10 ⁷ P
a (80 ° C.), 1.3 × 10 ⁷ Pa (100 ° C.),
9 × a 10 ⁶ Pa (120 ℃), storage modulus E'2 at each temperature after standing 24 hours at such a film 4 hours immersion in boiling water to 23 ° C. is, 5.2 × 10 ⁸ Pa ( 60 ° C),
3.2 × 10 ⁷ Pa (80 ° C.), 9.0 × 10 ⁶ Pa (1
(00 ° C.) and 3.8 × 10 ⁶ Pa (120 ° C.).
From these measurements, E'2 /
When the value of E′1 was calculated, 0.71 (60 ° C.), 0.4
0 (80 ° C), 0.69 (100 ° C), 0.78 (12
0 ° C).

Comparative Example 1 In [Production of PVA (B)] of Example 1, methyl acetate was added to a methanol solution of polyvinyl acetate (average degree of polymerization: 1100) obtained by a conventional method. Methanol / water = 40 / 58.5 / 1.5 (weight ratio)
, And a saponification degree of 90.5 mol% (9.
5 mol%) of PVA (B). In addition, such PVA
The iodine color degree (I) of (B) was 0.03 as measured by the method described in the text. PVA obtained
Using (B), a dispersant for emulsion polymerization was obtained in the same manner as in Example 1, and a vinyl acetate resin emulsion (solid content: 39.6%, viscosity: 2.6 Pa · sec (25 ° C.)) was similarly obtained. It was manufactured and evaluated similarly. Table 1 shows the evaluation results of the examples and the comparative examples.

[0036]

[Table 1] Emulsion properties Low-temperature stability Leaving stability Hot water adhesion Example 1 ○ 50 <76 〃 2 ○ 50 <72 ３ 3 ○ 35 70 ４ 4 ○ 50 <65 ５ 5 ○ 30 70 〃 6 ○ ５０ 50 <75 Comparative Example 1 △ △ 10 20

[0037]

According to the present invention, the dispersant for emulsion polymerization is an AA-P
Since a VA and a PVA having a specific iodine coloration degree are used in combination, it is possible to obtain a vinyl resin emulsion having excellent properties such as fluidity, and excellent in low-temperature stability, storage stability, and water-resistant adhesiveness. When such an emulsion is used for an adhesive, it is very useful because it can obtain a (water-resistant) adhesive strength equal to or higher than that of a one-pack type and a two-pack type (base resin + crosslinking agent).

Continued on the front page F-term (reference) 4J002 BC031 BC051 BD031 BD101 BE022 BF021 BG041 BG051 BG101 BL011 BN151 GJ01 HA07 4J011 KA16 KB29 4J100 AA02Q AA03Q AA06Q AA19Q AA21Q AD02P AJ15QAJ15QAJ15QAJ15A

Claims (6)

[Claims] 1. A dispersant for emulsion polymerization, comprising a polyvinyl alcohol resin containing an acetoacetic ester group (A) and a polyvinyl alcohol resin (B) having an iodine coloration of 0.05 or more. . 2. The polyvinyl alcohol resin (B) having an iodine coloration of 0.05 or more has a saponification degree (SV mol%) and an iodine coloration (I) satisfying the following condition (1). The dispersant for emulsion polymerization according to claim 1, characterized in that: 4.26 ≦ I + 0.047 × SV ≦ 4.73 (1) 3. A polyvinyl alcohol-based resin (B) having an iodine coloration of at least 0.05 obtained by saponifying a polyvinyl acetate-based polymer in the presence of a solvent having a dielectric constant of 32 c.gsesu or less. The dispersant for emulsion polymerization according to claim 1 or 2, wherein 4. The acetoacetate group-containing polyvinyl alcohol-based resin (A) has an acetoacetate group content of 0.5 to 5 mol%.
3. The dispersant for emulsion polymerization according to any one of 3. 5. A vinyl resin emulsion using the dispersant for emulsion polymerization according to claim 1. 6. The obtained film has a storage modulus of 60 to 12
The vinyl resin emulsion according to claim 5, wherein the following formula (2) is satisfied in a range of 0 ° C. E'2 / E'1> 0.25 (2) (where E'1 is the storage elastic modulus (Pa) of the obtained film before immersion in boiling water, and E'2 is 4 Soak in boiling water for 23 hours
Represents the storage elastic modulus (Pa) after standing for 24 hours, and the value of the storage elastic modulus is a value at the same temperature for both E′1 and E′2.)