NO772297L - WATER CATALYST MATERIALS FOR POLYMERIZATION - Google Patents

Description

Aqueous catalyst materials for polymerization

In the case of polymerization in an aqueous dispersion, the catalysts, which are usually present as solid materials, are added in the form of solutions in organic solvents to the polymerization charge. Thereby, solvents are introduced into the polymerization charge, and these solvents are also found in the final product and have a disruptive effect in several ways.

Thus, e.g. food hygiene concerns by using polymers containing such solvents in packaging materials. In addition, company safety problems can arise when handling organic solvents both during polymerization and during the further processing of solvent-containing polymers.

Moreover, the use of dissolved solid catalyst materials in organic solvents is unfortunate because the catalyst activity decreases when the solution is stored and the catalyst solution must therefore preferably be refreshed each time before it is used.

A number of catalysts are also sold in a phlegmatized state with water, whereby the water content can be up to 30% by weight. When these catalysts are dissolved in organic solvents, heterogeneous phases often occur which make accurate dosing of the catalyst difficult.

The invention therefore aims to transfer polymerisation ion catalysts to a storage-stable pumpable or doseable form, whereby at the same time a finely distributed application form of the catalyst is obtained which enables accurate dosing while avoiding the disadvantages caused by the use of catalysts dissolved in organic solvents.

The invention thus relates to catalyst materials. which are distinctive in that they consist of an aqueous dispersion with 1-40% by weight of oil-soluble catalysts which are storage-stable at a temperature above -5°C, from the group dialkyl-, diacyl- or diaryl peroxides and/or peroxydicarbonates and/or organic azo compounds and/or mixed anhydrides of organic sulfoperic acids and organic acids and/or organic peresters, 0.01-5% by weight natural or synthetic protective colloids and/or. 0.5-20% by weight anionic, cationic and/or non-ionic emulsifiers with a dispersion particle size. of less than 300 µm, preferably 1-100 µm.

The invention also relates to a method for the production of catalyst dispersions which are finely divided in water and which are not prone to sedimentation and which contain oil-soluble radical initiators, and the method is characterized by the fact that 1-40% by weight of oil-soluble radical initiators are transferred to stable, pumpable dispersions under the influence of strong shear forces and in the presence of 0.01-5% by weight of protective colloids and/or 0.5-20% by weight of emulsifiers.

The dispersions of solid, oil-soluble radical initiators in water are used for polymerization in aqueous dispersion, preferably for the suspension polymerization, and especially for the microbead polymerization.

With this catalyst preparation, it has been successful to transfer oil-soluble radical initiators to a storage-stable pumpable or doseable form, where the catalyst is present in a finely divided state, and at the same time to overcome the disadvantages that oil-soluble radical initiators that are dissolved in an organic solvent are subject to.

The use of water as a continuous phase in which protective colloids and/or emulsifiers are dissolved limits the catalyst types to those which are storage-stable above the solids point,

•for the continuous phase. As the.lowest solids point can

usually a temperature of -5°C is considered, but by adding melting point lowering materials the range can be extended to lower temperatures. Up is the temperature range, limited only by the catalyst's decomposition temperature.

All radical initiators which are suitable for suspension polymerization can be used for this purpose, as the suspension polymerization, or the microbead polymerization is carried out in the presence of one or more of the following monomers: doubly ethylenically unsaturated monomers, such as e.g. butadiene, isoprene, 1,4-pentadiene, 1,6-hexadiene,, and 1,7-octadiene, single ethylenically unsaturated monomers, such as e.g. styrene or substituted styrenes such as e.g. methylstyrene, 2,4-dimethylstyrene, ethylenestyrene, isopropylstyrene, butylstyrene, phenylstyrene, cyclohexylstyrene and benzylstyrene, halogen-substituted styrenes such as e.g. chlorostyrene, 2,5-dichlorostyrene, bromostyrene, fluorostyrene, trifluoromethylstyrene and iodostyrene, styrenes which are substituted with functional groups, such as e.g. cyanostyrene, nitrostyrene, acetostyrene and phenoxystyrene, acrylic monomers and substituted acrylic monomers such as e.g. acrylic acid and methacrylic acid and their esters with 1-18 carbon atoms, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, isopropyl (meth) acrylate, butyl acrylate, 2-ethylhexyl acrylate, phenyl (meth) acrylate, acrylonitrile and methacrylonitrile, vinyl esters and substituted vinyl esters with carboxylic acids with 1-18 carbon atoms, such as e.g. vinyl formate, vinyl acetate, chlorovinyl acetate, vinyl butyrate, vinyl methoxy acetate and vinyl benzoate, methyl-4-vinyl benzoate and isopropenyl acetate, vinyl esters with unsaturated carboxylic acids with 1-8 carbon atoms, such as e.g. vinyl acrylate and vinyl methacrylate, vinyl halides such as vinyl fluoride, vinylidene chloride, vinyl bromide, vinylidene bromide and vinyl iodide, vinyl compounds with functional groups, such as p-vinylidene sulphide, p-vinylphenylphenyloxide and vinylpyridine, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether, vinyl butyl ether and vinyl-2-ethylhexyl ether, vinyl phenyl ether, vinyl ketones such as e.g. vinyl ethyl ketone and vinyl phenyl ketone, and allyl esters with carboxylic acids with 1-18 carbon atoms, but especially vinyl chloride.

As sparingly soluble radical initiators for suspension polymerization, resp. microbead polymerization, dialkyl-, diaryl- or diacyperoxides such as ditert.buty1-, dilauryl-, dimyristyl-, dicetyl-, distearyl-, bi.s-2 , 4-dichlorobenzoyl-, diacetyl-bg acetylbenzoyl peroxide, peresters such as tert. propyl per-acetate, tert-butyl peracetate, tert-butyl peroctoate and tert-butyl perpivalate, dialkyl peroxydicarbonates such as diisopropyl-, diethyl-, dihexyl-, dicyclohexyl-, dialkylcyclohexylperoxydicarbonate. and bis-(4-tert. butylcyclohexyl)-peroxydicarbonate, and also the dialkylperoxydicarbonates with alkyl chain lengths of 8-18 carbon atoms, and the mixed anhydrides of organic sulfoperic acids and organic acids, such as acetylcyclohexylsulfbnylperoxyd, and also azo compounds which are known as polymerization initiators, which azoisobutyric nitrile and azovaleronitrile.

The radical initiators can be used in the dispersion in an amount of 1-4 0<y>ect% depending on whether the total amount of emulsifier solution used for the polymerization is used for dispersing the catalyst or the catalyst is used separately in the form of a concentrated dispersion .

Suitable emulsifiers are anion-active, cation-active and non-ionic emulsifiers with an HLB value (hydrophilic-lyophilic balance) between 5 and 18 and mixtures thereof, such as e.g. fatty soaps, alkyl sulfates and alkyl sulfonates with 8-18 carbon atoms in the alkyl chain, alkanesulfonates, alkylbenzene sulfonates, alkyl-naphthalene sulfonates, sulforaic acid esters, partially esterified phosphoric acid, cationically active alkyl ammonium salts, and alkylphenols with 6-22 carbon atoms in the alkyl chain and with 5-30 molecular units of condensed ethylene oxides . Further usable emulsifiers are the ammonium salt of dlhydroxystearic acid (DHW 80) or "Texapon K 12" (=sodium lauryl sulfate).

The emulsifiers can be used in an amount of 0.5-20% by weight.

The emulsifier concentration is i.a. depending on whether the amount of emulsifier required for the polymerization is added together with the catalyst for the polymerization or whether the emulsifier solution is added separately from the catalyst dispersion.

The emulsifiers used for the catalyst dispersion can e.g. be the same as those used for the polymerization.

Many times, however, different emulsifiers can also be used for the catalyst dispersion and polymerization, but it must then be ensured that the effects of the emulsifiers do not mutually cancel each other out. This must be ensured, e.g. when different HLB values are required for the emulsification of the catalyst and the monomer. Anionic emulsifiers are frequently avoided in suspension polymerization.

Suitable protective colloids are synthetic and natural polymeric materials with possibly water-soluble properties, such as polyvinyl alcohols, partially acetylated polyvinyl alcohols, water-soluble cellulose derivatives, hydroxyethyl-, propyl-, methyl- and carboxymethylcellulose, water-soluble starch ethers, polyacrylic acid, water-soluble polyacrylic acid copolymers with acrylamide and/or alkyl esters, poly-N-vinyl compounds of open-chain or cyclic carboxylic acid amides, and polyvinylpyrrolidone. In addition, e.g. copolymers of styrene and maleic anhydride ("Lytron 820") are suitable. The protective colloids are usually used in an amount of 0.01-5% by weight.

The catalyst dispersion is prepared by spreading it in water containing 0.01-5% by weight of protective colloids and/or 0.5-20% by weight of emulsifiers, under the influence of strong shear forces on the mixture. Devices which in this context can be used for obtaining such shear forces are, for example, emulsifying devices of the "Ultra-Turrax" type, "In-line" mixing devices, colloid mixing devices or also colloid stick mills, whereby the mixture when it passes through the mixing device or by repumping, is transferred to a dispersion with the required particle size. The mill has a rotor-stator combination with toothed surfaces as a grinding element. The grinding material has a reduced particle size and is dispersed when it passes through the mill under the influence of strong shear and frictional forces. As the catalysts are usually temperature sensitive, it is advantageous that the temperature does not usually exceed 20°C during the paint-down process, but the temperature can also be easily regulated by adjusting the supply of water to or by water cooling the machine.

The particle size of the catalyst in the dispersion is usually below .300 µm, and a particle size for the catalyst in the dispersion of 100 µm-1 µm has been shown to be favorable for the polymerization. A small particle size for the catalyst in the dispersion is favorable for absorption of the catalyst in monomers. This is particularly advantageous when the catalyst already before the actual reaction room, e.g. already along a section for preliminary mixing, must be mixed homogeneously with a monomer dispersion.

The production of polymer latexes from monomers using the catalyst system according to the invention, water, protective colloids and/or emulsifiers is carried out by adding the catalyst dispersed in the protective colloid and/or in the solution containing the emulsifier, or by the concentrated catalyst dispersion containing only such an amount of protective colloids and/or emulsifiers which are necessary for dispersing and stabilizing the catalyst against sedimentation are used. The individual components, such as protective colloid solutions, emulsifiers, monomer and catalyst dispersion/can be added directly to the polymerization charge or along a so-called premixing section. So-called mixing pipes with flow-disturbing devices for direct supply to the reactor can be mentioned as pre-expanding sections,

•or a ring line as a storage and mixing line. After

that the autoclave has been heated to the reaction temperature, the polymerization takes place, and it is usually necessary to cool down during the polymerization. After the polymerization has ended, the polymer latex formed is worked up.

It is particularly advantageous to use the catalyst in the form of

an aqueous dispersion by suspension or microperl.epolymerization. The handling of larger amounts of solvent which was previously common during the polymerization is avoided by the use of the catalyst material according to the invention. The product quality of the polymers is improved by the fact that solvents from the traditional catalyst solution no longer have to be taken into account.

It has also succeeded in further reducing the residual volatility of the polymerization products when using the present catalyst material.

Example 1

a) A weak ammoniacal solution (pH 9-10) of 3 1 water,

3.5% by weight of ammonium dihydroxystearate and 1% by weight of ammonium styrene maleate are prepared in a container fitted with a stirrer. The container's contents are then pumped in a circuit through a mill of the "Fryma" type while adding a total amount of 25% by weight dilauryl peroxide. The obtained dispersion contains no proportions greater than 300 µm, and 95% by weight of the dispersion particles have a size below 100 µm.

b) The procedure according to example la) was repeated, but using 4% by weight of ammonium dihydroxystearate without ammonium styrene maleate. The obtained dispersion contains no proportions greater than 300 pm, and 95% by weight of the dispersion particles

have a size below 100 µm.

c) (Microbead suspension polymerization). The procedure according to example la) was repeated, but using 1% by weight of et

alkyl sulphonate (C-^)* The properties of the dispersion correspond to the properties stated in la) and lb).

Example 2

Suspension polymerization

■ a) (Comparison test)

2.6 kg of water, 1.4 kg of vinyl chloride, 20 g of dilauryl peroxide dissolved in toluene (20% solution) and 3.1 g of polyvinyl alcohol

(40 mol% acetate content) was in a laboratory autoclave. of V4A stirred with a propeller stirrer at 300 rpm and heated to 52°G.

The pH was adjusted to 5 by adding Nal^PO^. After a reaction time of 8 hours, a conversion of 85% by weight was achieved, and the product had a K value of 70 and an average grain size of 120 pm, and 100% of the particles had a size below 300 pm, while the proportion of volatile materials was 1.5% by weight. 1.2% by weight

was identified as toluene.

b) The procedure according to example 2a) was repeated, but using 100 g of 20% dilauryl peroxide dispersion as used

according to example la). The polymerization proceeded as described in example 2a). The catalyst dispersion is therefore just as suitable for polymerization as a catalyst solution, but the catalyst dispersion leads to the product only having a residual volatility of 0.3% by weight, which essentially consists of water.

Example 3 Microbead suspension polymerization

a) (Comparison test)

After they had been mixed in a ring line and homogenized

(as described in German Patent No. 1069387), 5850 1 of a 1% emulsifier solution (ammonium salt of dihydroxy-γ-stearic acid), 5850 1 vinyl chloride, 40 1 20% dilauroylperoxydicarbonate solution and 0.5 1 ethylhexyl percarbonate solution in toluene filled in a 14 m<3> tower autoclave, heated to 50°C and polymerized for 18 hours. A polymer with a K value of 70 was obtained, which after processing had a. proportion of volatile materials of 0.5% by weight. 0.3% by weight was identified as toluene.

b) The procedure according to example 3a) was repeated, but with the difference that instead of the dissolved catalyst, 36 1

catalyst suspension (20%) according to example la) used. After 18 hours, a vinyl chloride polymer was formed with a K-value of 70 and with a proportion of volatile materials of 0.2% by weight which essentially consisted of water.

Claims (3)

1. Catalyst material, characterized in that it consists of an aqueous dispersion with 1-40% by weight of oil-soluble catalysts which are storage-stable at a temperature above -5°C, from the group of diacetyl or diaryl peroxides and/or peroxydicarbonates and/or organic azo compounds and/or mixed anhydrides of organic sulphonic acids with organic acids, and/or organic <p> esters ,.0 ,0 1 - 5% by weight natural or synthetic protective colloids and/or 0.5 - 20% by weight anionic, cationic or non-ionic emulsifiers and with a particle size in the dispersion of less than 300 pm , preferably 1 - 100 pm. 2. Method for the production of catalyst dispersions which are not prone to sedimentation, characterized in that oil-soluble radical initiators in an amount of 1-40% by weight, based on the overall dispersion, is dispersed under the influence of strong shear forces in the presence of water, 0.01-5% by weight protective colloids and/or 0.5-20% by weight emulsifiers. 3. Use of dispersions of solid, oil-soluble radical initiators in water in the presence of 0.01 - 5% by weight of protective colloids and/or 0.5 - 20% by weight of emulsifiers with a particle size below 300 µm for polymerization in an aqueous dispersion, preferably suspension polymerization, and preferably microbead polymerization.