FI63247B - FOERFARANDE FOER FRAMSTAELLNING AV DISPERSIONER GENOM EMULSIONSPOLYMERISATION AV VINYLESTRAR - Google Patents

Description

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Italia-Italien (lT) 29601 A / 76 (71) Anic SpA, Via M. Stabile 2l6, Palermo, Italia-Italien (lT) (72) Adolfo Caporossi, Ravenna, Claudio Foschi, Forli ', Italia-Italien (lT) (lk) Antti Impola (5 ^) Method for preparing dispersions by emulsion polymerization of vinyl esters - Förfarande för framställning av dispersioner genom emulsionspolymerisation av vinylestrar

The invention relates to a process for the preparation of dispersions by emulsion polymerization of vinyl esters optionally with butyl maleate or alkyl acrylates having less than 12 carbon atoms in an aqueous medium in the presence of a water-soluble redox catalyst and a buffer system, and optionally also plasticizers and the like.

In particular, the invention relates to the dispersion polymerization of vinyl acetate as a monomer, either alone or in combination with other monomers, which is a vinyl monomer and / or an alkyl, aryl or cycloalkyl ester of an unsaturated mono- or bicarboxylic acid having 3 to 15 carbon atoms.

According to the prior art, the polymerization of vinyl acetate alone or with the above-mentioned monomers takes place at a temperature of generally 65 ° to 70 ° C, which temperature corresponds to the boiling point of the monomers.

Such a temperature is initially achieved by heating the jacket of the reaction vessel with steam. Higher reaction temperatures can be achieved by performing the polymerization under reduced overpressure.

Thus, short reaction periods are achieved, but the products are of poor quality 2 63247, especially those intended for use in the adhesive industry.

It has now surprisingly been found possible to overcome the disadvantages of the prior art and to obtain high-quality products by polymerizing at lower temperatures and using considerably shorter reaction times, in addition to which it is possible without initial heating of the reaction components.

The invention is characterized in that the polymerization is carried out in two steps, the first step comprising preparing a mixture at a temperature of 25-65 ° C of the following components: a) 10-70% by weight of said monomers, b) a large excess of stoichiometric reduction system with sodium formaldehyde sulfoxylate and water , acetate and / or sulphate of the eighth group of the Periodic Table, c) an ordinary protective colloid, d) an ordinary capillary active medium, e) an ordinary aldehyde chain transfer agent with an aqueous oxidizing mixture of thallium peroxides and bicarbonate and bicarbonate acetate, all the latter substances being added together, the second step being a continuous addition of an oxidizing mixture and the remaining part of the monomer at a constant temperature of not less than 60 ° C.

The object of the invention is to prepare adhesives in the form of aqueous dispersions with a high viscosity and very small polymer particles, using small amounts of protective colloids and, in fact, no capillary active substances.

According to DE 25 03 453, the reduction mixture of the redox system is gradually added at a temperature of 20 to 30 ° C as a constant, while according to the invention, a monorner is gradually added as the German patent applies to the copolymer. According to the invention, two temperature ranges are used and this technique produces two particle sizes, which is very useful when using an adhesive, as some of the particles travel to the pores of the bodies to be glued and the other particles anchor to form a bridge between the two bodies to be glued.

According to DE-25 03 M53, again one heat range is used so that the particle size distribution takes place in a narrower range than in the present invention. The dispersion according to the invention is very viscous 3 63247 and does not decrease even if the dispersion is diluted relatively much with water. According to the invention, this property makes the dispersions very suitable for water-based paints.

The process according to the invention comprises the following treatment steps: a) feeding the filler into the polymerization vessel, and first the whole reduction system, the total amount of acetate and / or sulphate, the total amount of chain transfer agent and the total amount of protective colloid, and the monomer / vinyl acetate or other monomer as defined above) only a portion corresponding to 10 to 70% by weight of the total weight of the monomer, suitably 25 to 45% by weight, b) fed to a reaction vessel to which the components listed in a) have been added in a continuous stream, and gradually a mixture of ../ with an oxidation system and / or an alkali metal or alkaline earth metal bicarbonate and / or acetate and maintaining the temperature of the reaction vessel at 25 to 65 ° C, c) being fed slightly before the reaction of the one or more monomers fed is complete, the remaining monomer or monomers are gradually and continuously, and at the same time the process described in (b) is continued; ) gradually and at the same rate as the mixture of the oxidation system and the alkali metal or alkaline earth metal bicarbonate or acetate, keeping the temperature at least 60 ° C;

This series of treatments results in the formation of two groups of particles, the first of which is formed at a lower temperature of 25 · ..65 ° C and is rich in protective colloid, and the particle diameter distribution is considerably wider, while the second group is formed at a higher temperature, which is kept constant. , and the particle diameter distribution is within narrow limits.

This heterogeneous nature of the particles is particularly well suited to the production of adhesives, where when assembling the joints together, a portion of the polymer particles must migrate towards the interior of the porous support element, while other particles must adhere to the outer surfaces and thus emphasize the polymer.

4 63247

Another advantageous feature of the process according to the invention is that the dispersions obtained, which have a high viscosity, and remain exceptionally constant despite dilution.

This latter property is one of the most interesting in the field of dispersions used in the manufacture of adhesives and in the formation of water-based adhesive products, in addition to which rheological properties And shear strength, which are also at a high level.

It is also interesting to note that by appropriately varying the amount of monomer in the charge And in the feed stream, emulsions can be obtained, which have varying degrees of polydispersity, and thus different viscosity levels, but which still retain their best technological properties and high performance.

It has also surprisingly been found that by applying the process according to the invention, the fouling of the reactor is considerably reduced at the same time. Removal of any residues from the karst can only be done by washing with water at low temperature. Other advantageous properties that can be achieved are an achievable increase in the efficiency of the polymerization process, which can be in the range of 40 ... 50%.

As already mentioned above, the process according to the invention can be applied to the preparation of dispersions of vinyl ester and / or carboxylic acid esters. Vinyl acetate should be mentioned as a typical vinyl ester, as this compound is currently used to the greatest extent.

Other vinyl esters include vinyl propionate, vinyl laurate, esters of unsaturated carboxylic acids,

Of which particularly preferred results include butyl maleate, ethyl hexyl maleate, alkyl acrylate, wherein the number of carbon atoms of the alkyl radicals is less than 12.

The following are a few examples to illustrate the invention.

EXAMPLE 1 - REFERENCE PRODUCTS

The following components, charged to 100 parts of monomer, are charged to a 16 liter steel polymerization reactor with a stirrer and a reflux condenser: 63247 vinyl acetate 100 parts water 95 "partially saponified polyvinyl alcohol (alkaline alcoholysis)" (35%) 0.35 "

All components are added, as well as 20 parts of vinyl acetate, followed by heating to 68 ° C, and the polymerization is carried out by feeding the remaining vinyl acetate over 4 hours and at a reaction temperature of 68 to 70 ° C.

Analysis results: solids 50.5% viscosity 22,500 cps (centipoise) pH 4.4 sediment 180 ppm (parts per million) mechanical stability sufficient removed scum 520 g viscosity after dilution with water (25 parts water) 500 cps resistance to freezing poor resistance to melting cycles poor mechanical stress shelf life sufficient particle size 7% about 5 nm 75% "3000 nm 18%" 1000 "a few lumps EXAMPLE 2 vinyl acetate 100 parts water 95" partially saponified polyvinyl alcohol (basic alcoholation) aldehyde formate 7 * 5 "sodium .35 "propionaldehyde 0.14 N cobalt acetate 0.003"

hydrogen peroxide (35%) 0.3 M

sodium carbonate 0.14 n

Water, polyvinyl alcohol pre-dissolved in water, sodium formaldehyde sulfoxylate, propionaldehyde, cobalt acetate and 4 parts of vinyl acetate are initially charged.

6 63247 The addition of hydrogen peroxide and bicarbonate is then started in small portions.

The remaining vinyl acetate is fed at 55 ° C over 2 hours and the reaction temperature is kept below 80 ° C. Analysis results: solids 50.7% viscosity 37,000 cps pH 4.5 sediment 110 ppm mechanical stability very good removed scale 20 g viscosity after dilution (25 parts water) 6,500 cps resistance to freeze-thaw cycles very good resistance to mechanical stress very good viscosity unchanged shelf life very good particle size 40% about 500 nm 60% less than 500 nm no lumps EXAMPLE 5 vinyl acetate 100 parts water 95 "polyvinylpyrrolidone (K90) 7" sodium dodecylbenzenesulfonate 0.4 "sodium formaldehyde sulfobolate 0.4" sodium formaldehyde sulfobilate "hydrogen peroxide (35%) 0.3" sodium carbonate 0.16 "

The reaction is carried out as in Example 2, and the reaction temperature does not exceed 80 ° C.

Analysis results: solids 50.6% viscosity 17,000 cps pH 4.45 ___ sediment 40 ppm 7 63247 mechanical stability very good removed scum 25 g resistance to freeze-thaw cycles very good shelf life very good particle size 60% about 1000 nm 40% " 500 nm no lumps EXAMPLE 4 vinyl acetate 100 parts water 90 "methylcellulose (400 cps) 3" sodium dodecylbenzenesulfonate 0.25 "

nonylphenyl polyglycol ether 0.5 M

propionaldehyde 0.2 ”cobalt acetate 0.0025” sodium formaldehyde sulfoxylate 0.18 "dibutyl phthalate 25 parts hydrogen peroxide (35 0.35" sodium bicarbonate 0.15 "

Water, methylcellulose, sodium dodecylbenzenesulfonate and nonylphenol polyglycol ether, all pre-dissolved in water, propionaldehyde, sodium formaldehyde sulfoxilate and 30% vinyl acetate and dibutyl phthalate are charged.

After the reaction is started, hydrogen peroxide and sodium bicarbonate are added in small portions, and the remaining vinyl acetate and dibutyl phthalate are maintained, maintaining the reaction temperature at about 60 ° C. Analysis results ϊ solids 55 »5% viscosity 13,500 cps pH 4.4 sediment 42 ppm mechanical stability very good removed scale 37 6 resistance to freeze-thaw cycles very good wear resistance in humid environment very good resistance to soaping agents good 8 63247 shelf life very good particle size 60% about 500 nm 40% less than 500 nm no lumps EXAMPLE 5 vinyl acetate 100 parts dibutyl maleate 25 "water 80" hydroxyethylcellulose 3 "nonylphenol polyglycol ether 2" sodium dodecylbenzenesulfonate 0.3 "sulfaldehyde 0.3" vinyl .07 "acetaldehyde 0.10" hydrogen peroxide (35%) 0.55 "methanol 10 parts

sodium bicarbonate 0.25 M

All of the above components are added, with the exception of hydrogen peroxide and sodium bicarbonate, which are added in small portions based on the reaction temperature. The polymerization is carried out at a maximum of 70 ° C.

Analysis results: solids 56.3% viscosity 12,500 cps pH 4.2 sediment 110 ppm mechanical stability very good removed scum 42 g resistance to freeze-thaw cycles very good abrasion resistance in humid environments good resistance to soaping agents good shelf life very good particle size 70 % about 500 nm 30% less than "" no lumps 63247 EXAMPLE 6 vinyl acetate 100 parts water 87 "partially saponified polyvinyl alcohol (acidic alcoholysis) 715" sodium formaldehyde sulfoxylate 0.35 "propionaldehyde 0.14" cobalt acetate 0.003 " .3 "sodium bicarbonate 0.12"

The reaction is carried out in the same manner as in Example 2, and the reaction temperature does not exceed 75 ° C.

Analysis results: solids 53 »5% viscosity 27,000 cps pH 4.7 mechanical stability very good removed scum 18 g viscosity after dilution (25 parts water) 4,400 cps resistance to mechanical stress very good resistance to freeze-thaw cycles very good shelf life very good particle size 70% about 500 nm 30% less than "" no lumps EXAMPLE 7 vinyl acetate 100 parts water 95 "partially saponified polyvinyl alcohol (basic alcoholysis) 7" 5 "sodium formaldehyde sulfoxylate 0.32" propionaldehyde 0.12 "cobalt acetate hydrogen peroxide (35%) 0.28 "10 63247 sodium bicarbonate 0.17"

The reaction is carried out in the same manner as in Example 2. The reaction temperature is maintained at about 70 ° C.

Analysis results; solids 49.9% viscosity 79,000 cps pH 4.5 sediment 115 ppm mechanical stability very good removed scale J1 g viscosity after dilution (25 parts water) 8,200 cps resistance to mechanical stress very good "to freeze-thaw cycles very good shelf life very good particle size 30% about 500 nm 70% less than "" no lumps EXAMPLE 8 vinyl acetate 100 o part water 95 "partially saponified polyvinyl alcohol (basic alcoholysis) 7.5" sodium formaldehyde sulfoxylate 0.32 "propionaldehyde 0.12" cobolate 03 "hydrogen peroxide (35%) 0.28" sodium bicarbonate 0.17 "

The reaction is carried out in the same manner as in Example 2, but 50 parts of vinyl acetate are added to the allele, and 50 parts are continuously added thereafter. The reaction temperature is 70 ° C.

Analysis results; solids 50.3% viscosity 50,000 cps pH 4.7 sediment 95 ppm mechanical stability very good removed scaling 27 g 11 63247 viscosity after dilution (25 parts water) 5,800 cps resistance to mechanical stress very good resistance to freezing very good shelf life with respect to melting cycles very good particle size 50% about 500 nm 50% less than "" no lumps EXAMPLE 9 vinyl acetate 100 parts water 270 "partially saponified polyvinyl alcohol (basic alcoholysis) 12" sodium formaldehyde sulfoxylate 0.35 "propionaldehyde 12 ”cobalt acetate 0.03” hydrogen peroxide (35%) 0.30 "sodium bicarbonate 0.19 parts

The reaction is carried out in the same manner as in Example 2 and the reaction temperature is at most 70 ° C.

Analysis results: solids 36.5% viscosity 34,000 cps pH A, 6 sediments 46 ppm mechanical stability very good removed scaling 30 g viscosity after dilution (25 parts water) 5,700 cps resistance to mechanical stresses very good resistance to freeze-thaw cycles very good shelf life very good particle size 50% about 500 nm 50% less than "" no lumps 12 63247 EXAMPLE 10 vinyl acetate 100 parts water 135 "hydroxyethylcellulose 4" polyglycol ether 2.5 "sodium dodecylbenzenesulfonate 0.3" vinyl disulfonate 0.2 "vinyl sulfonate .52 "vinyl versatate 40" propionaldehyde 0.25 "hydrogen peroxide (35%) 0.3" sodium bicarbonate 0.2 "methanol 10"

All components are added together and 1/3 of vinyl acetate, vinyl versatate and propioaldehyde are used. The addition of bicarbonate and hydrogen peroxide is then started. After the temperature has risen to 60 ° C, the remaining vinyl versatate, vinyl acetate and propionaldehyde are initially added, and the reaction temperature is maintained at a maximum of 80 ° C. After completion of the reaction and cooling of the reaction mixture, methanol and water (1: 1) are added. Analysis results: solids 51.2% viscosity 2,800 cps pH 4.4 sediment 8.0 ppm mechanical stability very good resistance to freeze-thaw cycles very good resistance to wear in humid environments very good resistance to soaping agents very good accelerated shelf life very viscosity unchanged

Claims (3)

13 63247 A process for preparing dispersions by emulsion polymerization of vinyl esters optionally supplemented with butyl maleate, ethyl maleate or alkyl acrylates having less than 12 carbon atoms in an aqueous medium in the presence of a water-soluble redox catalyst and a buffer system, and optionally other softeners, and optionally the polymerization is carried out in two stages, the first of which involves the preparation of a mixture at 25 ° C to 65 ° C of the following components: a) 10 to 70% by weight of the monomers in question, b) a large excess of stoichiometric reduction system acetate and / or sulphate of the element of the eighth group, c) an ordinary protective colloid, d) an ordinary capillary active medium, e) an ordinary aldehyde chain transfer agent with the addition of an aqueous oxidant open a mixture of water-soluble peroxides and bicarbonate and / or alkali metal or alkaline earth metal acetate, all the latter substances added together simultaneously, the second step continuously adding an oxidizing mixture and the remaining part of the monomer not exceeding 60 ° C; at a constant temperature. Process according to Claim 1, characterized in that cobalt acetate and / or sulphate are also added. Process according to Claim 1, characterized in that hydrogen peroxide is used as oxidizing agent in the presence of sodium or potassium bicarbonates and / or acetates.