EP0000590A1 - Aqueous dispersions of vinyl chloride copolymers, process for producing them and their use - Google Patents

Abstract

Knowledgeable vinyl chloride copolymer dispersions; the comonomers are vinyl acetate and ethylene, and optionally olefinically unsaturated methylolamides, which are prepared by polymerization in an aqueous medium using a redox catalyst system in the presence of 2 to 15 percent by weight. One or more polyvinyl alcohols with saponification numbers between 20 and 240 and degrees of polymerization between 300 and 2000. The dispersions produced in this way are used as binders in hydraulically setting building materials and, in combination with hardener additives, in adhesives and paints.

Description

The invention relates to aqueous copolymer dispersions with high proportions of vinyl chloride units, ir. Polymers containing only polyvinyl alcohol as protective colloid, their production and their use.

Aqueous copolymer dispersions containing vinyl chloride, vinyl acetate and ethylene units are known from laid-open publications 21 19 549 and 22 52 285. In order to achieve stable dispersions, it has always been necessary to take special measures with regard to the protective colloid / emulsifier system.

Furthermore, it was often essential to maintain critical amounts of ionic or non-ionic emulsifiers. These special colloid stabilization systems consisting of emulsifiers, protective colloids and auxiliary monomers can not only be reproducibly observed under relatively complicated technical conditions, but sometimes also have an effect on various uses of the dispersions, for example in adhesives or concrete admixtures. Adhesives containing auxiliary monomers or emulsifiers generally have lower water resistance: Older applications, such as F 15 300 IV b / 39c, describe the production of thermostable polymers or copolymers of vinyl chloride. However, it is emphasized as specific to the invention that the polymerization or copolymerization must under no circumstances be carried out until the monomers, vinyl chloride or vinyl acetate have been largely consumed.

The object of the invention was to find copolymer dispersions which without auxiliary monomers, i.e. without monomers with strongly polar groups, e.g. of carboxyl, sulfonic acid, carbonamide groups or emulsifiers are to be polymerized economically to stable dispersions.

• 50 - 85 Gewichtsprozent Vinylchlorideinheiten
• 5 - 35 Gewichtsprozent Vinylacetateinheiten und
• 5 - 30 Gewichtsprozent Äthyleneinheiten besteht und als Schutzkolloid
• 2 - 15 Gewichtsprozent eines oder mehrerer Polyvinylalkohole, bezogen auf die Dispersion, mit Verseifungszahlen zwischen 20 und 240 und Polymerisationsgraden zwischen 300 und 2000 enthält.

The invention relates to aqueous vinyl chloride copolymer dispersions with solids contents of between 30 and 70 percent by weight, which are characterized in that the dispersion consists of copolymers

• 50-85 weight percent vinyl chloride units
• 5 - 35 weight percent vinyl acetate units and
• 5 - 30 weight percent ethylene units and as a protective colloid
• Contains 2-15 percent by weight of one or more polyvinyl alcohols, based on the dispersion, with saponification numbers between 20 and 240 and degrees of polymerization between 300 and 2000.

For certain uses of the dispersions, it is advantageous to additionally polymerize in 0.5 to 5 percent by weight of units of olefinically unsaturated N-methylolamides.

The stated resin compositions represent limit ranges. In some cases it may be advantageous to use copolymer dispersions with compositions of 60 to 80 percent by weight vinyl chloride units, 8 to 20 percent by weight vinyl acetate units and 10 to 25 percent by weight ethylene units and 0.5 to 5 To strive for weight percent of units of olefinically unsaturated N-methylolamides.

Examples of olefinically unsaturated N-methylolamides are N-methylolacrylamide; N-methylol methacrylamide; N-methylolallyl carbamate; N-methylolallyl ether, Mannich bases, N-methyl ester of N-methylolacrylamide; N-methylol methacrylamide or N-methyl olallyl carbamate.

The dispersions are produced in heated and coolable stirred autoclaves. For this purpose, the required amount of polyvinyl alcohol, generally 2 to 15 percent by weight, preferably 4.5 to 12 percent by weight, based on the dispersion, with saponification numbers between 20 and 240 and 300 to 2000 monomer units in the polymer molecule, dissolved in water, is initially introduced. One type of polyvinyl alcohol can be used alone, but also mixtures of different polyvinyl alcohols. The polymerization is generally carried out using redox catalyst amounts between 0.01 and 3 percent by weight. In general, the entire required amount of the oxidizing catalyst portion, or its main amount, is presented and the polymerization is controlled by metering in the reducing agent. However, the reducing agent can also be introduced in a known manner and the reaction with the oxidizing agent can be controlled. Finally, it is also possible to control the polymerization by metering in both components at the same time. 0.01-0.5 percent by weight, preferably 0.03-0.3 percent by weight, of reducing agent and 0.01-2 percent by weight, preferably 0.03-0.8 percent by weight of oxidizing agent are required, the ratio of oxidizing agent depending on the process to reducing agent is 0.15 to 6. Examples of the oxidizing component of the catalyst are ammonium or potassium persulfate, hydrogen peroxide and t-eutylhyfroperoxide. Examples of the reducing agent component are sodium sulfite, sodium metabisulfite, zinc or sodium formaldehyde sulfoxylate. H ₂ / noble metal sol catalysts are equally suitable under _ early use of small amounts of heavy metal salts as activators. Suitable redox catalyst systems are described, inter alia, in "Fundamental Principles of Polymerization", GF D'Alelio, John Wiley & Sons Inc., New York 1952 on pages 333.ff.

Before the start of polymerization, 10 to 20 percent by weight of the total amount of vinyl chloride and vinyl acetate are usually metered into the polyvinyl alcohol solution and the polymerization batch is saturated with ethylene. The polymerization batch is stirred. The polyvinyl alcohol can be wholly or only partially, i.e. for example, half. The monomer concentration of the liquid monomers should not fall below 5 percent by weight and not exceed 20 percent by weight during the monomer metering.

The ethylene pressure used varies between 20 and 150 bar, depending on the amount of ethylene to be installed. The preferred pressure range is 35 to 100 bar. The pressure required is highly dependent on the viscosity and the stirring effect in the polymerization batch. The lower the viscosity and the better the material circulation in the autoclave, the less ethylene pressure is required to incorporate the desired amount. Ethylene in the resin, of course, taking into account the copolymerization and solubility parameters.

The polymerization temperature is 10 to 85 ° C, preferably 20 to 50 ° C. In the course of the reaction, the remaining vinyl chloride and vinyl acetate and the 0.5 to 5 percent by weight of the olefinic unsaturated N-methylolamides, the methylol group of which may also be etherified, are fed to the reaction vessel, the ethylene pressure being kept constant.

The reaction time depends, for example, on the heat dissipation, ie the stirring and cooling system, and the desired monomer concentration during the polymerization and the catalyst system down. In general, the polymerization is complete when there is no longer any noticeable heat development and the vinyl acetate monomer concentration has preferably dropped below 1.5 percent by weight.

The polymerization is generally complete after 10 to 20 hours. The reaction mixture is then polymerized by adding additional catalyst and by heating until the vinyl acetate content is below 0.5 percent by weight. For this purpose, catalyst amounts of 0.005-0.1 percent by weight, preferably 0.01-0.04 percent by weight, based on the dispersion of the oxidizing agent and the reducing agent, are generally necessary.

The dispersions of the invention can be used in a variety of ways. They show pigment stability and are ideal as binders in emulsion paints. The relatively good flame resistance, the high binding capacity and the high saponification resistance enable the dispersions to be used as binders in hydraulically setting building materials, and they also show high adhesive strength and water resistance when used in adhesives. In combination with trivalent acid hydrolyzing metal salts, there are favorable pot lives and water resistance. The same applies in connection with strong protonic acids, e.g. Phosphoric acid, sulfuric acid and sulfonic acids, hydrochloric acid. In the case of salts, the hardener additives are added to the dispersion in the form of their concentrated aqueous solution, in the case of salts (20 to 70% by weight), in the case of protonic acids (10 to 50% by weight) in amounts of 2 to 10% by volume.

The properties of the dispersions when used in wood bonds with the addition of trivalent inorganic salts, such as chromium nitrate or aluminum nitrate, were tested in accordance with DIN 68603. Fine is assessed according to the highest stress classes of this standard after a longer cold water storage or a longer boiling water storage (storage sequence No. 9 of the standard = B4 / 9). Other important sizes that determine the use properties of dispersion adhesive describes substances in combination with inorganic salts is the pot life. This should be longer than a week for use in certain adhesive application units. These conditions are sometimes exceeded considerably by the adhesives used in combination with hardener additives.

When using the dispersion according to the invention as a binder in hydraulically setting building materials and in paints, it is customary to add emulsifiers to the dispersions in amounts of 0.05 to 1.5 percent by weight. Suitable non-ionic emulsifiers include aliphatic ethers of polyoxyethylene, e.g. Polyoxyethylene lauryl ether, oleyl ether and alkylaryl ether, polyoxyethylene octylphenyl ether, nonylphenyl ether, esters and amides, such as polyoxyethylene laurate, oleate, isonate, N-polyoxyethylene lauramide, are also suitable. Block polymers of ethylene and propylene oxide can also be used. It is also often advantageous to use defoamers in amounts of 0.05 to 0.3 percent by weight of the active substance.

When using the dispersions as paints, acidic salts or strong protonic acids are added as with the adhesives. This results in a waterproof coating. Such acidic salts are, for example, trivalent metal salts of the main and subgroup of the periodic system of the elements with strong protonic acids. Preferred hardeners in this connection are acidic phosphates, phosphoric acid, aluminum nitrate and chromium (III) nitrate. These paints made from dispersion and hardener have favorable pot lives and work e.g. corrosion-resistant on iron with excellent adhesion. Here too, the hardeners for salts are added to the dispersion in the form of their concentrated aqueous solution or the pro- tonic acids in semi-concentrated form in amounts of 2 to 8 percent by weight.

An inorganic, setting material such as hydraulic cement, Portland cement, natural cement (Roman cement) or alumina cement is used as the mortar binder. Common cement additives such as Gypsum, gypsum mortar, calcium phosphate, lime or other such calcium-containing binders, magnesium oxychloride, magnesite or other magnesium-containing or oxysalt compositions or other similar setting inorganic substances, such as are used as binders for unmodified concrete and mortar compositions, can optionally be added. Sand, stones, concrete, crushed stone, gravel, granite, carborundum, aluminum oxide, emery, marble quarry, sawdust, slag, asbestos, mica, talc, flint stones or art products such as powdered ceramic materials are used as usual aggregate materials.

When using the dispersions in paints, the latex coating compositions can e.g. (Capped) polyisocyanates, water-condensable urea formaldehyde or thermosetting melamine formaldehyde resins are added. Pigments such as clays, aluminum silicates, calcium carbonate, magnesium carbonate, mica, talc, diatomaceous earth or titanium oxide, zinc phosphates, zinc chromates, iron oxide, chromium oxide can also be added. Of course, alkaline-reacting and carbonate-containing products can only be added if no acidic hardeners are added. Many other processing aids known to those skilled in the art, such as thickeners, coalescing aids, fillers and reinforcing agents, plasticizers, leveling agents and bulking agents, antioxidants and stabilizers, and fungicides can also be used. The paints are suitable as protective or decorative coatings for metal, wood or mineral surfaces, for example.

Fillers are also occasionally added when the dispersions are used in waterproof adhesives. Light spar, heavy spar and other mineral substances are mentioned which do not react alkaline and do not contain a carbonate group. In certain cases, protective colloids, in particular polyvinyl alcohol, are added subsequently. Preservatives, dyes, plasticizers, film-forming aids and thickeners may be mentioned as further possible additives. Examples of plasticizers are butyl diglycol acetate, butyl acetylrizinol and diesters oxalic acid, succinic acid, adipic acid, phthalic acid with aliphatic, branched or unbranched alcohols with 2-16 carbon atoms, such as, for example, dibutyl oxalate, dibutyl succinate, diiosbutyl phthalate, dioctyl phthalate, diisotridecyl phthalate and glycols, such as hexamethylene glycol, such as ethyleneglycol, such as ethyleneglycol Diphenoxyphenyl formal. Organic solvents in the form of aromatic hydrocarbons or aliphatic hydrocarbons can also be added.

example 1

400 g of polyvinyl alcohol with a saponification number of 60 and a Höppler viscosity of 13 m Pa.s (a 4% by weight aqueous solution at 20 ° C.) are dissolved in 2.4 l of water together with 40 g of potassium persulfate. A mixture of 4.2 kg of vinyl chloride and 0.8 kg of vinyl acetate is metered in continuously with stirring and at a polymerization temperature of 30 ° C. The ethylene pressure is kept constant at 50 bar during the entire polymerization time. The polymerization was started by adding a 1% sodium formaldehyde sulfoxylate solution and controlled by further addition of reducing agent. In total, the consumption of reducing agent of the concentration mentioned was 770 g (7.7 g of reducing agent 100%). The polymerization was complete after 15 hours. In the post-polymerization phase were again

2.67 g of Rongalit C, dissolved in 15 ml of water (= 0.02% by weight on dispersion) 2.67 g of t-butyl hydroperoxide added (= 0.02% by weight on dispersion)

The dispersion obtained has a solids content of 51.8 percent by weight, a viscosity, measured in the Epprecht rheometer stage C III of 5900 m Pa.s and a minimum film formation temperature of 20 ° C. The dispersion is frost, pigment and shear

• Lgf. (Lgf = Lagerungsfolge der DIN 68603) Nr. 5 2,7 N/mm² Lgf. Nr. 9 4,0 _N/mm²

stable and has good strength values. After adding 2 percent by weight of butyl diglycol acetate to the dispersion, the tear strength of the film was approximately 12.5 N / mm ² with an elongation at break of approximately 350%. The examination of wood bonds with a mixture of the dispersion with 5% by weight of a 40% by weight, prepared from 70 parts by weight of the water containing (9 H ₂ O) salt in 30 parts by weight of water, gave an aqueous solution of chromium (III) nitrate DIN 68603 the following adhesive strengths:

• Lgf. (Lgf = positioning sequence of DIN 68603) No. 5 2.7 N / mm ² Lgf. No. 9 4.0 _{N /} mm ²

When the dispersion is used as a concrete additive using a conventional defoamer in an amount of 0.1 percent by weight, based on the dispersion, the values listed in the table are obtained. The defoamer consists of 94 percent by weight dimethylpolysiloxane with a viscosity above 20 centistokes at 25 ° C, 6 percent by weight silicon dioxide in finely divided form. With a plastic / cement factor of 0.05 and a water / cement factor of 0.48, the following values are determined:

Example 2

_J e 275 g of a polyvinyl alcohol having a saponification number of 70 and viscosities of 13 and 6 m Pa.s are dissolved together with the catalyst as in Example 1 in water. With the same process conditions as in Example 1, only with the difference that a solution of 50 g of N-biethylolaczylamide in 100 cc of water / methanol (1: 1) is metered in simultaneously with the vinyl chloride-vinyl acetate metering.

A dispersion is obtained with a solids content of 51.7 percent by weight, a viscosity (rheometer stage C III) of 4930 m Pa.s and a minimum film-forming temperature of 15 ° C. It is frost, pigment and shear stable and has good strength values. The test according to DIN 68603 as an adhesive with the addition of chromium (III) nitrate (the amount mentioned in Example 1) gave Lgf. No. 9 4.1 N / mm ²

Example 3

Under process conditions as in Example 2, but using twice the amount of N-methylolacrylamide and 440 g of a mixture of polyvinyl alcohol with a saponification number of 140. 140 g of which have a Höppler viscosity of 13 and 300 g of 5 m Pa.s.

The dispersion produced in this way is frost, pigment and shear stable, has a solids content of 53.2 percent by weight and a viscosity measured in the Epprecht rheometer (stage C III) of 11,700 m Pa.s.

The following values were obtained when testing the adhesive strength according to DIN 68603. With the addition of chromium nitrate (5% by weight of the dispersion of a 70% aqueous solution)

Aluminum nitrate (5% by weight of a 70% aqueous solution. The concentration given says: 70% based on the brine containing 9 water of crystallization).

Example 4

If the procedure is otherwise the same as in Example 3, polyvinyl alcohol with a saponification number of 20 is used. The Höppler viscosity of the polyvinyl alcohols used is 13 or 5 m pa.s.

The test of the adhesive strength according to DIN 68603 showed using chromium (III) nitrate (in the amount mentioned in Example 1)

Example 5

440 g of a polyvinyl alcohol with a saponification number of 140 and a Höppler viscosity of 5 m Pa.s are dissolved together with 40 g of potassium persulfate in water and heated to approx. 37 ° C. A mixture of 4.2 kg of vinyl chloride and 0.8 kg of vinyl acetate is then metered in continuously over the course of 5 hours. During this time, the ethylene pressure is kept at 50 bar and 175 g of N-methylolacrylamide are metered into an aqueous / methanolic solution.

The reaction is controlled by adding formaldehyde sodium sulfoxylate. The polymerization is complete after 14 hours, the product is adjusted to pH 7 with ammonia, let down, post-polymerized and degassed.

Aluminiumnitrat: Lgf. Nr. 9 4,8 N/mm² The dispersion obtained has a solids content of 52.5, a viscosity (rheometer C III) of 2500 m Pa.s and a minimum film-forming temperature of 20 ° C. It is resistant to shear pigment and frost and, when uncrosslinked, has a tensile strength of 18 N / mm ² with an elongation at break of approx. 290%. The test according to DIN 68603 shows when using chromium nitrate

Aluminum nitrate: Lgf. No. 9 4.8 N / mm ²

Subsequent addition of 1 percent by weight polyvinyl alcohol on dispersion changes these values insignificantly.

The pot life is over 20 days. 5% 25% by weight phosphoric acid: Lgf. No. 9 4.5 N / mm ² pot life: over 14 days 5% 25% by weight sulfuric acid: Lgf. No. 9 4, ON / mm ² pot life: over 14 days

Example. 6

The polymerization is carried out very analogously to Example 3, but a polyvinyl alcohol with a saponification number of 200 was used.

The solids content of the dispersion is 52.9 percent by weight, the viscosity (rheometer C III) 7300 m Pa.s and the minimum film forming temperature 25 ° C. The pigment- and poorly stable dispersion has a K value of 63.

Example 7

• 1) Reaktionstemperatur: 30°C
• 2) N-Methylolacrylamid: 210 g

The following changes are made compared to experiment 5:

• 1) Reaction temperature: 30 ° C
• 2) N-Methylolacrylamide: 210 g

The solids content of the dispersion is 54.1 percent by weight, the viscosity (rheometer C III) is 4750 m Pa.s and the minimum film formation temperature is 1.8 ° C. It is frost, pigment and shear stable.

Example 8

• 1) Reaktionstemperatur: 40 - 45°C
• 2) N-Methylolacrylamid: 230 g (4 Gewichtsprozent)

Compared to example 5, the following changes are made:

• 1) Reaction temperature: 40 - 45 ° C
• 2) N-methylolacrylamide: 230 g (4 percent by weight)

The pest content of the dispersion is 53.1 percent by weight, the viscosity (rheometer C III) is 2800 m Pa.s and the minimum film formation temperature is 14 ° C. It is frost, pigment and shear stable.

The test according to DIN 68603 showed with chromium nitrate:

Example 9/10

Replacing N-methylolcarylamide in Example 8 with the corresponding methoxy or isobutoxy ether did not result in a significant change in the dispersion properties.

Example 11

Compared to example 5, the following change was made:

The solids content of the dispersion is 53.9 percent by weight, the viscosity (rheometer C III) is 3400 m Pa.s and the minimum film-forming temperature is 16 ° C.

The test according to DIN. 68603 with aluminum nitrate added:

Example 12

The polymerization is carried out analogously to Example 5, but instead of 175 g of N-methylolacrylamide, 175 g of N-methylolallylcarbanate are polymerized in.

The product has a solids content of 51.4 percent by weight, a viscosity (rheometer C III) of 2100 m Pa.s and a minimum film formation temperature of 19 ° C. It is frost, pigment and shear stable.

The test according to DIN 68603 shows when chromium nitrate is added:

Aluminum nitrate:

Claims (6)

1. Aqueous vinyl chloride copolymer dispersions with solids contents between 30 and 70 percent by weight, characterized in that the dispersion of copolymers 5 ₀ - 85 weight percent vinyl chloride units 5 - 35 weight percent vinyl acetate units and Contains 5 to 30 percent by weight of ethylene units and 2 to 15 percent by weight of one or more polyvinyl alcohols, based on the dispersion, with saponification numbers between 20 and 240 and degrees of polymerization between 300 and 2000. 2. Aqueous vinyl chloride copolymer dispersion according to claim 1. characterized in that an additional 0.5 to 5 percent by weight of units of olefinically unsaturated N-methylolamides are copolymerized. 3. Process for the preparation of vinyl chloride copolymer dispersions having a content between 30 and 70 percent by weight by polymerization in an aqueous medium at temperatures between +10 and + 85 ° C. using 0.01 to 3 percent by weight redox catalyst systems with stirring and post-polymerization with the addition of a further 0.005 to 0.1 percent by weight of the respective components of the redox catalyst system, characterized in that based on the total solids content of the dispersion 50-85 weight percent vinyl chloride 5 - 35 percent by weight vinyl acetate and optionally 0.5 to 5 percent by weight of an olefinically unsaturated N-methylolamide at constant ethylene pressures between 20 and 150 bar in the presence of 2 to 15 percent by weight of one or more polyvinyl alcohols with saponification numbers between 20 and 240 and degrees of polymerization between 300 and 2000 is polymerized at monomer concentrations of the liquid monomers during the monomer metering between 5 and 20 percent by weight. 4. Use of the dispersions according to claim 3 as binders in hydraulically setting building materials. 5. Use of the dispersions according to claims 1 to 3 in combination with acidic hardener additives in adhesives. 6. Use of the dispersions according to claims 1 to 3 in combination with aluminum nitrate, chromium nitrate, acid phosphates or phosphoric acid as hardener additives in paints.