JPH0250121B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a polymer latex capable of forming a film with excellent water resistance and adhesion.

[Conventional technology and its problems]

Polymer latexes are widely used industrially in the fields of paints, adhesives, pressure-sensitive adhesives, paper processing agents, fiber processing agents, etc., either as they are or with the addition of various additives.

Polymer latex is generally produced by the well-known emulsion polymerization method in which monomers are emulsified and dispersed in an aqueous medium containing a surfactant and polymerized using a polymerization catalyst that generates radicals. The polymer inside has a concentration of 40-65% by weight and a particle size of 0.01.
~1 micron and exists in a stable dispersion.

Surfactants play the important role of providing a polymerization site for monomers in an aqueous medium and keeping the emulsion-dispersed state stable for a long period of time.
Because it is water-soluble and inherently lacks compatibility with polymers,
Its presence greatly impairs the water resistance and adhesion of the polymer film formed by drying the latex.

Because of these drawbacks, latexes, which are advantageous in terms of ease of handling and safety and hygiene, cannot be used in applications where high water resistance is required for coatings, and organic solvent solutions of polymers, which are inferior in these aspects, cannot be used. In some cases, it is necessary to use latex, and the essential drawbacks of latex, such as improving water resistance and adhesion, have been the most important problems to be solved.

Techniques for improving the water resistance and adhesion of coatings formed from polymer latex include incorporating crosslinking agents such as melamine resins, urea resins, epoxy resins, isocyanate compounds, and aziridine compounds, and incorporating various types of compounds into the polymer. There are methods to introduce functional groups and perform high heat treatment to cause a crosslinking reaction, but these methods require high heat treatment at 150°C or higher, and are two-component, which limits the usable time. Therefore, it was difficult to use it for general purpose.

Therefore, many efforts have been made to eliminate the adverse effects of surfactants in polymer latexes. An example of this is the Tokuko Sho 46-12472
Special Publication No. 46-34894, Special Publication No. 49-46291, Special Publication No. 51-44157, Special Publication No. 56-29657, Special Publication No. 1977.
-29658, JP-A-51-30284, JP-A-51-
No. 30285, JP-A-54-144317, JP-A-55-11525
No., JP-A-55-38821, JP-A-55-115418,
JP-A-55-115419, JP-A-58-7468, JP-A-Sho
There are publications such as No. 58-203960. These examples relate to ethylenically unsaturated monomers having sulfonic acid groups or polyoxyethylene groups, so-called reactive emulsifiers, or emulsion polymerization methods using them, which can be used in place of ordinary surfactants. It is something.

However, serious problems arise when these methods are simply applied industrially. First of all, due to the problem of polymerization stability, if we try to use the reactive emulsifier shown in the above-mentioned publication at a polymer concentration of 40% or more, which is usually practiced industrially, the polymerization stability will be unacceptably high. Agglomerates can form and significantly impede the filtration process, or the presence of fine agglomerates in the polymer latex can impair the uniformity of the coating formed. A second problem is that the water resistance and adhesion of coatings formed from latexes polymerized using such reactive emulsifiers cannot reach the expected level.

[Means for solving problems]

The present inventors have made extensive studies to solve the above-mentioned problems and have completed the present invention.

That is, the present invention provides the method of preparing (a) 0.5 to 50 ethylenically unsaturated monomers having a carboxyl group in an aqueous medium.
(b) Ethylenically unsaturated monomer 45-99.45% by weight, (c) Allyl sulfosuccinate represented by any of the following formulas (), (), (), () 0.05-5
(d) acrylic ester or methacrylic ester 15.05 to 99.5% by weight in the presence of the seed latex prepared in the first step; Weight%, (e) ethylenically unsaturated monomer with carboxyl group 0 to 10% by weight, (f) ethylenically unsaturated monomer [excluding acrylic esters and methacrylic esters] 0 to 69.95
% by weight, (g) a second stage in which a monomer mixture consisting of 0.05 to 5% by weight of styrene sulfonate represented by the following formula () is introduced and polymerized, and the polymer formed in the first stage is The combined weight ratio is
The present invention relates to a method for producing a polymer latex characterized in that the ratio is 5/95 to 80/20.

(In the above formula, R ₁ is hydrogen or a methyl group, R ₂ is a hydrocarbon group or an organic group containing a hydrocarbon group having a substituent or an oxyalkylene group, and A has 2 to 2 carbon atoms.
4 alkylene groups or substituted alkylene groups, n means 0 or a positive number. M means an alkali metal, ammonium, an organic amine group or an organic quaternary ammonium base. ) (In the above formula, M represents an alkali metal, ammonium, organic amine base, or organic quaternary ammonium base.) If the above requirements of the present invention are not met, a large amount of fine aggregates will be generated during emulsion polymerization. In addition, defects appear in the water resistance and adhesion of the coating, and the dispersion stability of the polymer latex deteriorates.

In addition, in the present invention, the second stage can be divided into two or more stages and implemented within a range that satisfies the above requirements.

Examples of the ethylenically unsaturated monomer having a carboxyl group in the present invention include acrylic acid,
Examples include methacrylic acid, itaconic acid, fumaric acid, maleic acid, and maleic anhydride.

In the present invention, the ethylenically unsaturated monomer refers to an ethylenically unsaturated monomer that does not have a carboxyl group, and includes aromatic monomers such as acrylic esters, methacrylic esters, styrene, and vinyltoluene, and vinyl acetate. , vinyl esters such as vinyl propionate and vinyl versatate, vinyl cyanides such as (meth)acrylonitrile, vinyl halides such as vinyl chloride and vinylidene chloride, and various functional monomers such as ( meth)acrylamide, diacetone acrylamide,
(meth)glycidyl acrylate, 2-hydroxyethyl (meth)acrylate, N-ethylolacrylamide, N-butoxymethylacrylamide,
Phosphooxyethyl methacrylate, 3-chloro-2-phosphooxypropyl acrylate, methylpropanesulfonic acid acrylamide, divinylbenzene, allyl (meth)acrylate, (poly)oxyethylene di(meth)acrylate, Includes methylolpropane triacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, and the like.

Acrylic ester or methacrylic ester (hereinafter simply referred to as (meth)acrylic ester). ] Examples include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, dodecyl (meth)acrylate, and 2-ethylhexyl acrylate.

Conventional emulsion polymerization methods can be employed to carry out the present invention. The polymerization catalyst is one that causes addition polymerization of monomers through radical decomposition using heat or reducing substances, and includes water-soluble or oil-soluble persulfates,
Peroxides, azobis compounds, etc. can be used. Examples include potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, 2,2-azobisisobutyronitrile, 2,2-azobis (2-amidinopropane) hydrochloride, 2,2-azobis(2,4-dimethylvaleronitrile), etc.
In particular, water-soluble ones are preferably used, and the amount thereof is usually 0.1 to 1% by weight based on the monomer. In addition, when acceleration of the polymerization rate or polymerization at a lower temperature is desired, a reducing agent such as sodium bisulfite, ferrous chloride, ascorbate, Rongarit, etc. is used in combination with the polymerization catalyst.

It is also possible to add various polymerization regulators as desired, such as PH such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, sodium hydrogen phosphate, and sodium dihydrogen phosphate. These include regulators, chelating agents such as ethylenediaminetetraacetic acid and its salts, and chain transfer agents for adjusting the molecular weight of polymers.

In the present invention, conventional surfactants such as anionic surfactants such as fatty acid soaps, alkyl sulfonates, alkyl sulfosuccinates, polyoxyethylene alkyl sulfates, polyoxyethylene alkylaryl sulfates, and polyoxyethylene Although the use of nonionic surfactants such as alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene sorbitan fatty acid esters, and oxyethylene oxypropylene block copolymers is not excluded, the amount used is 100% by weight of the total monomer. The amount should be kept at 1 part by weight or less; use of more than that will impair the water resistance and adhesion of the coating.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a polymer latex that forms a coating having a high degree of water resistance and adhesion that could not be achieved using conventional manufacturing techniques.

〔Example〕

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples, but it goes without saying that the scope of the present invention is not limited only to these Examples. Note that parts and percentages in the examples are by weight.

Example 1 15 parts of methacrylic acid, 30 parts of methyl methacrylate, 15 parts of styrene, and 2-acrylic acid were placed in a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank, and a thermometer.
Add 40 parts of ethylhexyl, 300 parts of water, and 4 parts of a 39% aqueous solution of sodium allylalkylsulfosuccinate (Eleminol JS-2, manufactured by Sanyo Chemical Industries, Ltd.).
After raising the internal temperature to 78°C, add 15 parts of a 2% aqueous solution of ammonium persulfate and maintain for 1 hour. This prepares the first stage seed latex.

Next, 90 parts of styrene, 117 parts of methyl methacrylate
190 parts of 2-ethylhexyl acrylate, 3 parts of methacrylic acid, 3 parts of sodium p-styrenesulfonate (Spinomer NaSS, manufactured by Toyo Soda Kogyo Co., Ltd.), 1.2 parts of ammonium persulfate,
An aqueous solution consisting of 184 parts of water was flowed into the reaction vessel from a separate dropping tank over a period of 3 hours. After the inflow is finished, the temperature is brought to 83°C and maintained for 2 hours. 25 after cooling
% ammonia aqueous solution was added to adjust the pH to 8, and the mixture was filtered through a 200 mesh filter cloth. The dry weight of the filtered aggregate was very small at 0.03% based on the total monomers.

Next, 10 parts of a 50% aqueous solution of butyl cellosolve and 5 parts of 2-ethylhexyl cellosolve were added to 100 parts of the obtained latex as film-forming aids, and the mixture was cast onto a glass plate to a thickness of 100 microns at 20°C. at 24
Dry for an hour. After immersing it in water at 20°C for 24 hours, its light transmittance was measured to be 98%.
Almost no whitening of the film was observed with the naked eye.

Next, a paint having the following formulation was prepared from the obtained polymer latex.

Prescription Pigment Diversion Water for Coating 52.1 Diethylaminoethanolaut 0.3 Demol EP (1) 7.3 Surfinol SE (2) 4.6 Ethylene Glycol 8.4 Typeke R930 (3) 204.6 Nopco 1497VD (4) 0.6 Letdown Polymer Latex 1000.0 Butyl Cellosolve 55.0 2 -ethylhexyl Cellosolve 14.0 Water 27.5 Nopco 1497VD 1.0 (Note) (1) Dispersant: Kao Soap Co., Ltd. (2) Wetting agent: Air Products Co., Ltd. (3) Rutile titanium oxide: Ishihara Sangyo Co., Ltd. (4) ) Antifoaming agent: Manufactured by San Nopco Co., Ltd. This paint was applied uniformly to a 5 mm thick asbestos slate board to a dry film thickness of 80 microns, and heated at 70°C.
Dry in the dryer for 15 minutes. When this coated plate was immersed in boiling water for 2 hours and then taken out and its condition was observed, no defects such as swelling, blistering, or peeling of the coating film were observed.

Example 2 14 parts of acrylic acid, 1 part of acrylamide, 45 parts of methyl methacrylate, 40 parts of n-butyl acrylate, 300 parts of water, and 300 parts of water were added to a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank, and a thermometer. 0.8 parts of oxyethylene nonyl phenyl ether (Emulgen 920, manufactured by Kao Soap Co., Ltd.), 39% aqueous solution of sodium allylalkylsulfosuccinate (Eleminol JS-2,
(manufactured by Sanyo Chemical Industries, Ltd.), and after raising the internal temperature to 78℃, add 15% of a 2% aqueous solution of ammonium persulfate.
of water and keep for 1 hour. This prepares the first stage seed latex.

Next, 90 parts of styrene, 117 parts of methyl methacrylate
190 parts of n-butyl acrylate, 3 parts of methacrylic acid, and sodium p-styrenesulfonate (Spinomer NaSS, Toyo Soda Kogyo Co., Ltd.)
An aqueous solution consisting of 1.2 parts of ammonium persulfate and 184 parts of water was poured into the reaction vessel from a separate dropping tank over a period of 3 hours. After the inflow is finished, the temperature is brought to 83°C and maintained for 2 hours. After cooling, add 25% ammonia aqueous solution to adjust the pH to 8, then 200.
It was filtered through mesh filter cloth. The dry weight of the filtered aggregate was very small at 0.04% based on the total monomers.

Next, 10 parts of a 50% aqueous solution of butyl cellosolve and 5 parts of 2-ethylhexyl cellosolve were added to 100 parts of the obtained latex as film-forming aids, and the mixture was cast onto a glass plate to a thickness of 100 microns at 20°C. at 24
Dry for an hour. After immersing this in water at 20°C for 24 hours, its light transmittance was measured to be 96%, and almost no whitening of the film was observed with the naked eye. or,
As in Example 1, the polymer latex obtained here was made into a paint and the boiling water resistance of the paint film was tested, and no swelling, blistering, or peeling phenomena were observed in the paint film.

Comparative Examples 1 and 2 When polymerization was carried out in the same manner as in Example 1 except that sodium p-styrene sulfonate was removed from the polymerization recipe of Example 1, aggregates were generated to the extent that filtration was difficult. The amount of aggregates retained on the 200 mesh filter cloth is
It was 0.5% based on the total monomers.

When polymerization was carried out in the same manner as in Example 2 except that sodium p-styrene sulfonate was removed from the polymerization recipe in Example 2, a large amount of aggregates were still generated.
The amount was 0.3% based on the total monomers.

When the water resistance of these polymer latex coatings was tested in the same manner as in Example 1, the light transmittance was 65% and 45%, respectively, and whitening and swelling phenomena were significant.

Comparative Example 3 15 parts of methacrylic acid, 30 parts of methyl methacrylate, 15 parts of styrene, and 2-acrylic acid were placed in a reaction vessel equipped with a stirrer, a reflux condenser, a dropping tank, and a thermometer.
40 parts of ethylhexyl, 300 parts of water, polyoxyethylene nonyl phenyl ether (Emulgen 920,
Add 5 parts of a 25% aqueous solution of Kao Soap Co., Ltd.) and 5 parts of a 25% aqueous solution of polyoxyethylene nonyl phenyl ether sodium sulfate (Levenol WZ, Kao Soap Co., Ltd.), and bring the internal temperature to 78°C. After raising the temperature, add 15 parts of a 2% aqueous solution of ammonium persulfate and hold for 1 hour.
This prepares the first stage seed latex.

Next, 90 parts of styrene, 117 parts of methyl methacrylate
190 parts of 2-ethylhexyl acrylate, 3 parts of methacrylic acid, polyoxyethylene nonyl phenyl ether (Emulgen 920, manufactured by Kao Soap Co., Ltd.)
A mixture consisting of 32 parts of a 25% aqueous solution, 16 parts of a 25% aqueous solution of polyoxyethylene nonyl phenyl ether sodium sulfate (Levenol WZ, manufactured by Kao Soap Co., Ltd.), 1.2 parts of ammonium persulfate, and 184 parts of water was poured into a reaction vessel. Let it flow over time. After the inflow is finished, the temperature is brought to 83°C and maintained for 2 hours. After cooling, add 25% ammonia aqueous solution to adjust the pH to 8, then 200.
It was filtered through mesh filter cloth. The dry weight of the filtered aggregate was very small at 0.03% based on the total monomers.

Next, 10 parts of a 50% aqueous solution of butyl cellosolve and 5 parts of 2-ethylhexyl cellosolve were added to 100 parts of the obtained latex as film-forming aids, and the mixture was cast onto a glass plate to a thickness of 100 microns at 20°C. at 24
Dry for an hour. After immersing it in water at 20℃ for 24 hours, its light transmittance was measured to be 68%.
The whitening phenomenon and swelling of the film were large. Furthermore, when a paint was prepared from this polymer latex according to the coating formulation described in Example 1 and similarly subjected to a boiling water resistance test, the coating film showed a significant blistering phenomenon.

Example 3 Into a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer, 97 parts of water and 5 parts of potassium persulfate were added.
% aqueous solution and raise the internal temperature to 80°C, add 4.5 parts of a 5% aqueous solution of potassium persulfate, 4.9 parts of a 5% aqueous solution of disodium hydrogen phosphate, and ammonium allylalkylsulfosuccinate (Latemul S-
180A, 2.5 parts of a 50% aqueous solution of Kao Soap Co., Ltd.), 69 parts of n-butyl acrylate, 4.5 parts of methyl methacrylate.
part, 1.5 parts of methacrylic acid, lauryl mercaptan
A mixture consisting of 0.1 part was run in over a period of 1 hour. This prepares the first stage seed latex.

Next, mixed monomers consisting of 216 parts of n-butyl acrylate, 12 parts of methyl methacrylate, 5 parts of methacrylic acid, and 0.23 parts of lauryl mercaptan, and sodium p-styrenesulfonate (Spinomer NaSS, Toyo Soda Kogyo Co., Ltd.) were added. ), 1 part of a 5% aqueous solution of potassium persulfate, 11 parts of a 5% aqueous solution of disodium phosphate hydroxide
and an aqueous solution consisting of 15 parts of water and 30 parts of water were respectively flowed into the reaction vessel from separate dropping tanks over a period of 3 hours.
After the inflow is finished, the temperature is brought to 83°C and maintained for 2 hours. After cooling, add 25% ammonia aqueous solution to adjust the pH.
7 and then filtered through a 200 mesh filter cloth. The dry weight of the filtered aggregate was very small, 0.03% based on the total monomers.

Next, the obtained polymer latex was uniformly coated onto a polyethylene terephthalate film having a thickness of 25 microns so that the dry coating had a thickness of 50 microns, and was dried at 105 DEG C. for 5 minutes. This coated film was pressed onto a plywood board using a 2 kg rubber roll and left for 24 hours. Next, put this in water at 20℃ for 24 hours.
The 180° peel adhesion strength between the film and the plywood was measured at 1200 g/25 mm after immersion for an hour. The peel adhesion strength before immersion in water is 1350g/
25 mm, and this polymer latex has excellent water-resistant adhesion for adhesives.

Example 4 Polymerization was carried out in the same manner as in Example 1 except that 3 parts of methacrylic acid was used in the next step following the preparation of seed latex in the first step. It was filtered through a filter cloth. Dry weight of filtered aggregate is 0.11 for total monomer
%, which was very small.

Comparative Example 4 Into a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer, 97 parts of water and 5 parts of potassium persulfate were added.
% aqueous solution and raise the internal temperature to 80°C, add 4.5 parts of a 5% aqueous solution of potassium persulfate, 4.9 parts of a 5% aqueous solution of disodium hydrogen phosphate, and polyoxyethylene nonyl phenyl ether (Emulgen).
9 parts of a 25% aqueous solution of polyoxyethylene nonyl phenyl ether sodium sulfate (Levenol WZ, manufactured by Kao Soap Co., Ltd.), 3 parts of a 25% aqueous solution of polyoxyethylene nonyl phenyl ether sodium sulfate (Levenol WZ, manufactured by Kao Soap Co., Ltd.), 69 parts of n-butyl acrylate. , 4.5 parts of methyl methacrylate, 1.5 parts of methacrylic acid, and 0.1 part of lauryl mercaptan were introduced over a period of 1 hour. This prepares the first stage seed latex.

Next, a mixed monomer consisting of 216 parts of n-butyl acrylate, 12 parts of methyl methacrylate, 5 parts of methacrylic acid, and 0.23 parts of lauryl mercaptan, and polyoxyethylene nonyl phenyl ether sodium sulfate (Levenol WZ, Kao soap ( Co., Ltd.), 11 parts of a 5% aqueous solution of potassium persulfate, 15 parts of a 5% aqueous solution of disodium phosphate hydroxide, and 30 parts of water were reacted in separate dropping tanks. Allow to flow into the container for 3 hours. After the inflow is finished, the temperature is brought to 83°C and maintained for 2 hours. After cooling, a 25% ammonia aqueous solution was added to adjust the pH to 7, and the mixture was filtered through a 200-mesh filter cloth. Dry weight of filtered aggregate is based on total monomer
It was very small at 0.04%.

Next, the obtained polymer latex was uniformly coated onto a polyethylene terephthalate film having a thickness of 25 microns so that the dried film had a thickness of 50 microns, and was dried at 105 DEG C. for 5 minutes. This coated film was crimped onto plywood using a 2 kg rubber roll.
It was left for 24 hours. Next, this was immersed in water at 20°C for 24 hours, and the 180° peel adhesive strength between the film and the plywood was measured, and it was 200 g/25 mm. The peel strength before immersion in water was 1500 g/25 mm, and this polymer latex had a major defect in water-resistant adhesion when used as an adhesive.

Comparative Example 5 Methacrylic acid 15 used in the preparation of the first stage seed latex from the polymerization recipe of Example 1
Polymerization was carried out in the same manner as in Example 1 except for 3 parts of methacrylic acid and 3 parts of methacrylic acid in the next step.
A large amount of agglomerates were generated that were difficult to filter with a micron filter cloth. This amount is 6.3% of the total monomer
It was hot.

Claims (1)

[Claims] 1 In an aqueous medium, (a) 0.5 to 50% by weight of an ethylenically unsaturated monomer having a carboxyl group, (b) 45 to 99.45% by weight of an ethylenically unsaturated monomer, (c ) The first step of obtaining seed latex by emulsion polymerization of a monomer mixture consisting of 0.05 to 5% by weight of allyl sulfosuccinate represented by any of the following formulas (), (), (), (). , in the presence of the seed latex prepared in the first step, (d) 15.05-99.5% by weight of an acrylic ester or methacrylic ester, (e) 0-10% by weight of an ethylenically unsaturated monomer having carboxyl groups. %, (f) Ethylenically unsaturated monomer [excluding acrylic esters and methacrylic esters] 0 to 69.95
% by weight, (g) a second stage in which a monomer mixture consisting of 0.05 to 5% by weight of styrene sulfonate represented by the following formula () is introduced and polymerized; The weight ratio of the polymer formed in the first step and the polymer formed in the second step is 5/95 to 5/95.
A method for producing a polymer latex characterized by an 80/20 ratio. (In the above formula, R ₁ is hydrogen or a methyl group, R ₂ is a hydrocarbon group or an organic group containing a hydrocarbon group having a substituent or an oxyalkylene group, and A has 2 to 2 carbon atoms.
4 alkylene groups or substituted alkylene groups, n means 0 or a positive number. M means an alkali metal, ammonium, an organic amine group or an organic quaternary ammonium base. ) (In the above formula, M represents an alkali metal, ammonium, an organic amine base, or an organic quaternary ammonium base.)