JPS5948002B2 - Method for producing aqueous polymer dispersion containing special dispersant - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polymer dispersion by using a special polymer as a dispersant during the polymerization of an olefinic unsaturated monomer in an aqueous emulsion.

When industrially producing aqueous dispersions of polymers such as styrene and/or acrylonitrile and butadiene, acrylic ester and/or vinyl ester polymers, and vinyl halides or vinylidene halides, The monomers are emulsified in water with so-called emulsifiers, also called soaps, and in the emulsified state they are polymerized under the action of radical-forming catalysts, in particular water-soluble peroxides such as hydrogen peroxide or alkali persulfates.

In many cases, polymer dispersions are obtained which exhibit good shear resistance and freezing resistance. Their pigment compatibility is still unsatisfactory in many cases, and their strong foaming properties pose great difficulties in many application processes, such as processing with high-speed coating machines. This is also a disadvantage when common protective glues such as polyvinyl alcohol, hydroxyethyl cellulose or vinylpyrrolidone copolymers are used in conjunction with the emulsion polymerization of olefinically unsaturated monomers. Therefore, during processing, antifoam agents such as special oxyalkylation products and (
or) silicone oil is added.

As a result, the surface tension of the emulsifier-containing dispersion produced by the conventional method, which is usually about 30 to 40 turns/cm,
This can be increased to 40 to 50 turns/me, but even with this method it has not been possible to completely avoid foaming. In addition, when a large amount of antifoaming agent is added, so-called eyeballs in paper making, a decrease in the adhesion of the thin polymer film on the substrate, and separation of the antifoaming agent forming two layers occur. In order to suppress the foaming tendency, (a) alkali salts and/or ammonium salts of monoalkyl sulfates and/or monoalkenyl sulfates and (b) esters with at least one hydroxyl group from fatty acids and polyhydric alcohols are used. An aqueous dispersion of the polymer was prepared by polymerizing an olefinically unsaturated monomer in an aqueous emulsion containing.

In this case, we were successful in reducing the bubbles to the point where they attracted attention, but
The foam formation of the dispersion is still unsatisfactory and the dispersions produced by this method have a surface tension of less than 45 dynes/CWL. The present inventors discovered that the aqueous medium used as a dispersant was a repeating unit of the following formula (wherein X represents -0- or -NH-, Y represents H or a cation, and n represents an integer from 1 to 8). When containing a water-soluble polymer having We have discovered that it is possible to produce a liquid.

This dispersant can be charged in combination with conventional emulsifiers and can be added at the beginning and/or during or at the end of the polymerization.

Aqueous dispersions prepared by the new polymerization process generally exhibit surface tensions of 55 dynes/CIIL or higher and are virtually non-foaming. In addition, this dispersion has remarkable resistance to shear forces, freezing and electrolytes, excellent pigment affinity, and very little wetting of many substrates, so that in many applications it is often used with surfactants (i.e. wetting). It is advantageous to add agents). Water-soluble polymers containing repeating units of general formula (1) are known.

Examples are the homopolymers of 2-acrylamido-2-methyl-propanesulfonic acid, 2-sulfoethyl acrylate and -methacrylate, 3-sulfopropylacrylate and -methacrylate and their salts, especially their sodium, potassium and ammonium salts. be. Also known are water-soluble copolymers of acrylic compounds having sulfonic groups of the above-mentioned type, which can be prepared using free radical-forming water-soluble catalysts such as hydrogen peroxide, alkali or ammonium persulfates, and redox catalysts. It can be produced in an aqueous medium by conventional methods of polymerization.
Comonomers which can be present in the water-soluble copolymer used for the process, generally in an amount of up to 50% by weight, based on the water-soluble polymer, include α, β, especially those having 3 to 5 carbon atoms. - Monoolefinically unsaturated mono- and dicarboxylic acids, such as in particular acrylic acid and methacrylic acid and their amides, as well as vinyl acetate, methyl acrylate, vinyl sulfonate and acrylonitrile.

The K value of homopolymers and copolymers having the repeating unit of general formula (1) and suitable for the polymerization method of the present invention is 1 at 20°C.
Generally 20 to 120, especially 40% when measured on aqueous solutions
~70, and homopolymers of said type are often preferred.

Of particular interest are the homopolymers of 2-acrylamido-2-methylpropanesulfonic acid and its water-soluble salts, especially its sodium salts having a K value of 20 to 120.

The sulfoesters used to prepare homopolymers and copolymers suitable as dispersants in the present process further include 1-sulfo-2-propyl acrylate, 2-sulfo-1-propyl acrylate, 2-sulfo-1-propyl acrylate, -propyl methacrylate, 2-sulfo-1-butyl acrylate and -methacrylate, 1-sulfo-2-butyl acrylate and -methacrylate, 3-sulfo-2-butyl acrylate and -methacrylate, 2-methyl-
2-Sulfo-1-propyl acrylate, 2-methyl-
1-sulfo-2-propyl acrylate, 3-sulfo-
They are 1-propyl acrylate, 3-sulfo-1-butyl acrylate, 4-sulfo-1-butyl acrylate and -methacrylate. Further examples of suitable sulfoalkyl amides of acrylic acid and methacrylic acid include 2
-acrylamidopropanesulfonic acid, 2-acrylamidoethanesulfonic acid, 2-methacrylamidoethanesulfonic acid, 4-acrylamidobutanesulfonic acid-1,
Examples include 3-acrylamidopropanesulfonic acid, 3-methacrylamidopropanesulfonic acid and acrylamide neopentylsulfonic acid. In the new emulsion polymerization process, common ethylenically unsaturated monomers can be used for the preparation of aqueous polymer dispersions.

For example, styrene and/or acrylonitrile in an amount of 30 to 70% by weight, in particular 40 to 60% by weight, based on the butadiene with the polymer, and optionally additionally 1 to 5% by weight, based on the total monomers. In quantity, α,
Preparation of a butadiene copolymer dispersion containing β-monoolefinically unsaturated monocarboxylic and/or dicarboxylic acids having 3 to 5 carbon atoms, such as in particular acrylic acid, methacrylic acid and fumaric acid. be able to. For example, monoolefinically unsaturated carboxylic acid esters often containing 3 to 20 carbon atoms, such as acrylic and methacrylic esters of methanol, ethanol, propanol, n-butanol, isobutanol or 2-ethylhexanol, acetic acid, Homo- and copolymer dispersions of vinyl esters of propionic acid, butyric acid or lauric acid, as well as acrylic- or methacrylic esters of the aforementioned type, with styrene and/or acrylonitrile and/or often monomers. Small amounts of α,β-olefinically unsaturated, often containing 3 to 5 carbon atoms, mono- and/or dicarboxylic acids or salts thereof, amides,
N-alkylamides or N-methylolamides (for example, in particular acrylic acid, methacrylic acid, crotonic acid, fumaric acid, acrylamide, methacrylamide, N-methylacrylamide, N-methylolacrylamide, N-
Methylolmethacrylamide, N-methoxymethylacrylamide, N-n-butoxymethylacrylamide,
Homo- and copolymer dispersions can be prepared from copolymers with N-methoxymethyl methacrylamide and N-butoxymethyl methacrylamide). Similarly, aqueous dispersions of polystyrene and polymers of vinyl halides, in particular vinyl chloride and vinylidene chloride, and ethylene, such as 70-90% by weight of vinylidene chloride and acrylonitrile and/or 1 10-30% by weight of acrylic esters of alkanols containing ~4 carbon atoms
or from 10 to 40% by weight, especially from 15 to 35% by weight, of vinyl acetate and/or vinyl chloride and ethylene. The amount of monomers of the above type to be polymerized in the aqueous emulsion according to the process of the invention is generally within the usual range, i.e.
It ranges from 0 to 70% by weight, especially from 40 to 60% by weight.

The polymerization temperature is also within the normal range, i.e. 0 to 150°C, especially 20°C.
~90°C, often 60-130°C (at standard conditions), and unless gaseous monomers are being polymerized or operating at temperatures above 100°C, polymerizations are often carried out under normal pressure. It will be done. In the process of the invention, the polymerization catalysts used are the generally water-soluble peroxide catalysts customary for the emulsion polymerization of olefinically unsaturated monomers, such as in particular hydrogen peroxide, sodium and potassium salts of persulfates and Mixtures of ammonium salts, perborates and redox catalysts such as hydrogen peroxide and ascorbic acid are used, optionally with addition of iron salts.

The amount of the water-soluble polymer having the repeating unit of general formula (I) can vary within a wide range, but is generally 0.05 to 5% by weight based on the olefinic unsaturated monomer to be polymerized.
In particular, it is 0.1 to 3% by weight, preferably 0.5 to 1.5% by weight. In general, the addition of conventional emulsifiers is not absolutely necessary in the polymerization process of the invention, but they may be added during the polymerization process, and the monomers are added in the aqueous phase when carrying out the so-called emulsion feeding process. In order to emulsify the part, it is often preferred to use small amounts of common emulsifiers. This results in a dispersion that is much less prone to foaming than conventionally produced dispersions containing emulsifiers. In addition, when using a small amount of emulsifier,
The particle size of the polymer dispersion can be controlled. Furthermore, when this method is actually carried out industrially as it is, for example when operating according to the so-called monomer feeding method, the addition of an emulsifier can be omitted. The polymer dispersion produced by the method of the present invention is superior to the dispersion produced by the conventional method, especially in terms of its high surface tension, and its stability is also excellent, and binders for nonwoven fabrics are a problem. In so far as it does not foam, it practically does not foam and can be used, for example, to produce floor coverings of needle sleet.

This floor covering does not produce white spots when rubbed vigorously, and when producing this type of non-woven fabric, losses due to so-called seepage absorption are reduced when drying the non-woven fabric impregnated with the dispersion. be done. Water having a repeating unit of general formula (1). Although soluble copolymers are known, their use as protective glues or dispersing agents is not.

For this reason, it is unexpected that stable polymer dispersions with virtually no tendency to foaming were obtained in the process of the invention. Furthermore, stable dispersions of 1,3-diene copolymers, such as those of butadiene-styrene and/or acrylonitrile copolymers, have hitherto been impossible to produce industrially using only emulsifiers alone. This was possible for the first time by using a protective colloid as a dispersant. Due to the very high surface tension of the aqueous polymer dispersions produced by the process of the invention, when using this new dispersion, common surfactants (or soaps) such as lauryl sulfate or fatty alkyl sulfonic acids are preferred. By adding salts, it is possible to obtain the optimum surface tension of the dispersion for the particular field of use, i.e. the desired wettability in the particular case of the substrate treated with this dispersion. In particularly high stability of 4
Surface tensions of 0 to 68 dynes/CrIL are often possible. The novel dispersions can be used as paints, impregnation agents and adhesives for generally flat substrates, optionally in pigmented form.

Owing to its excellent stability and pigment affinity, the aqueous polymer dispersion produced by the new method is particularly useful as a binder for paper coatings, as well as its high surface tension and no streaking. Especially suitable as a binder for non-woven fabrics. Furthermore, this polymer dispersion can be used as a raw material for adhesives.
As an additive to hydraulic binders, as a binder for pigmented printing pastes, as a coating for woven and non-woven flat structures such as films, paper and paperboard, and for the production of putties and filling materials. It is used as a raw material. The parts and percentages in the following examples are based on weight, and the K values of the dispersants described in the examples are according to the paper by Haichi Huikenchaichi in Tselrose Vol. 1, Vol. 13, p. 58 (1932). Measured at 20°C in the form of a 1% aqueous solution.

Example 1 117 parts of water, 0.2 parts of sodium persulfate in a stirred reactor
7 parts and 2.5 parts of sodium salt of poly-2-acrylamido-2-methylpropanesulfonic acid (K value 60) were charged and heated to 80°C, and the following additives 1 and 80°C were added at the same time. Add while maintaining the temperature in °C.

Finishing polymerization for 1 hour at 80° C. after the addition gives a 55% dispersion suitable as a raw material for adhesive substances.

The surface tension of the dispersion is 60 dynes/CTrL. Example 2 1350 parts of water, 40 parts of potassium persulfate, and 82 parts of sodium salt of poly-2-acrylamide-2-methylpropanesulfonic acid (K value 80) were charged into a pressure-resistant polymerization reactor, and the reactor was turned off. Rinse twice with nitrogen and finally place under 1 atmosphere of nitrogen pressure (preposition).

In a mixing vessel (additive 1), 3460 parts water, 1350 parts 3% aqueous sodium pyrophosphate solution, 20 parts sodium lauryl sulfate salt, 135 parts methacrylic acid amide, 278 parts acrylic acid, and 40 parts diisopropylxanthogen disulfide. 7,830 parts of styrene dissolved therein are thoroughly stirred and mixed.

The mixing vessel is flushed with nitrogen and then 5265 parts of butadiene are added. 37 of this monomer emulsion (additive 1)
75 parts are added to the prestock in the reactor. The mixture is heated to 130°C, and when the temperature reaches 75°C, further feeding of the monomer emulsion (Additive 1) is started.

The addition time is 2 to 3 hours, during which time the polymerization temperature is maintained at 130°C. Simultaneously with Additive 1, 5400 parts of a 2% potassium persulfate aqueous solution (additive) is supplied to the polymerization vessel.
After the addition of Additive 1 is completed, 1350 parts of a 2% hydrium persulfate aqueous solution (Additive 1) is further added to the reactor over 30 minutes.

A coagulum-free, 50% low viscosity dispersion is obtained, which forms a transparent film with very good adhesion on glass;
and has a surface tension of 62 dynes/me. Example 3 4,810 parts of water and 4 parts of potassium persulfate were placed in a king-resistant polymerization reactor.
0 parts, 100 parts of sodium salt of poly-2-acrylamido-2-methylpropanesulfonic acid (K value 40),
135 parts of methacrylic acid amide and 1350 parts of 3% aqueous sodium pyrophosphate are charged, washed with nitrogen, and then placed under 1 atm of nitrogen pressure (preposition).

In a mixing vessel (additive 1), 5265 parts of styrene in which 40 parts of diisopropylxanthogen disulfide is dissolved and 278 parts of acrylic acid are mixed with stirring.

The mixing vessel was flushed with nitrogen and then the butadiene 783
Add 0 parts. 700 parts of this monomer mixture are added to the prestock in the reactor and heated to 80°C, and when 50'C is reached the feeding of the remainder of the monomer mixture (Additive 1) is started. The addition time is 7 to 8 hours, during which time the polymerization temperature is maintained at 80 °C. Simultaneously with Additive 1, 5400 parts of a 2% aqueous potassium persulfate solution (Additive 11) is fed into the reactor. After the addition of additives 1 and n was completed, 1350 parts of a 2% potassium persulfate aqueous solution (additive 111) was added to 30 parts.
Add in portions. A 50% coagulum-free dispersion is obtained, which forms a transparent film with good adhesion on glass and has a surface tension of 62 dynes/CTn. Example 4 In a stirred reactor, 1160 parts of water, 20% aqueous solution of sodium salt of poly-r-sulfopropyl methacrylate (K
40), 0.5 parts of sodium lauryl sulfate, 32 parts of methacrylamide and 1.5 parts of potassium persulfate and heated to 90"C.

Additives 1 and n below were then heated at 90″C for 3 hours.
Add under stirring to the pre-preparation mixture kept at a temperature.

Additive 1: Styrol 773 parts Isobutyl acrylate 773 parts Acrylic acid 23 parts Additive 11: An aqueous solution of 8 parts potassium persulfate in 392 parts water followed by another hour of finishing polymerization to give a stable 50% dispersion. .

This liquid forms a transparent thin film and has a 62 dynes/CTI
It has a surface tension of L. Example 5 In a pressure-resistant stirred reactor, 650 parts of water, 1 part of sodium pyrophosphate, 0.5 part of sodium lauryl sulfate, 1 part of sodium persulfate, and a 20% aqueous solution of sodium salt of poly-r-sulfopropyl methacrylate (K Value 90) 50 parts are added under stirring and heated to 60"C.

Add the following additives 1 and... to this prefix for 60" while stirring.
Add at C for 5 hours. Additive 1: 850 parts of vinylidene chloride 100 parts of n-butyl acrylate 45 parts of ethyl acrylate Additive 11: An aqueous solution of 5 parts of sodium persulfate in 200 parts of water and then further polymerization for 1 hour 60' (11. , 50 with a surface tension of 58 dynes/CTIL, free of condensates.
% dispersion is obtained, which produces a tough thin film.

Claims (1)

[Claims] 1 The aqueous medium is a dispersant and the following formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) (In the formula, X represents -O- or -NH-, Y represents H or a cation, n
is an integer from 1 to 8), the olefinically unsaturated monomer is produced in an aqueous medium containing a dispersant using a common polymerization catalyst. A method for producing an aqueous dispersion of a polymer by polymerizing.