CS227842B1 - Isolation of grafted copolimers of abs resin type from latex - Google Patents

Description

The invention relates to the isolation of graft copolymers of the ABS type resins of their latexes prepared by emulsion polymerization.

Graft copolymers of ABS resin type are prepared by grafting a polymer which is at normal temperature in the glassy state and typically has a glass transition temperature T ≥ 90 to 120 ° C, to a polymer which is at the normal temperature in the rubbery state and usually T & Mp 100 - 0 ° C. The grafting is most often carried out by emulsion, suspension or block polymerization, and the obtained polymer is then isolated, dried and, if necessary, treated by the addition of suitable additives, dispatched.

When using emulsion polymerization techniques, the presence of alkylarylsulfonates-type emulsifiers is desirable in the polymerization system, in particular because of their ability to maintain cloid-etabilizing effects over a wide pH range, hydrolysis resistance, and relatively little effect on the heat resistance of the product. The isolation of polymers is carried out on a technical scale, usually by the addition of suitable electrolytes which cause destabilization of the latex particles, most often water-soluble calcium, magnesium or aluminum salts.

The form of the resulting coagulate is one of the factors that determines the amount of non-polymeric impurities and water retained in the polymer, respectively affecting the subsequent drying process and the quality of the isolated polymer. In order to obtain a coagulate suitable for further technological processing, according to MS. AO 173 244, coagulation should be performed at a temperature higher than the so-called thermal coagulation threshold characteristic of the polymer. The meaning of the term coagulation temperature threshold (tpk) is explained in more detail in the cited article. Ao 173 244. In practice, this temperature tpk is often near the boiling point of water. If the tpk is higher than 100 ° C it is necessary to work in pressure reactors, which has particularly adverse operational, technical, safety and economic consequences.

A disadvantage of latexes containing alkylarylsulfonates as emulsifier is the high temperature of the coagulation thermal threshold. In addition to the operational, technical, safety and economic consequences, high tpk also causes increased polymer aging rate during the process.

According to AO No. 209 716, it is known that the tpk value can be reduced by the addition of plasticizers in an amount of 0.5 to 10% by weight. parts per 100 wt. parts of the polymer. This method is particularly advantageous in cases where the plasticizer would otherwise be dosed at a later stage in the manufacture of the product, which is associated with a decrease in the heat resistance of the resulting polymer in cases where the plasticizer is dosed only to facilitate coagulation and with regard to heat resistance).

These drawbacks are greatly reduced or eliminated by the process of the invention.

According to the invention, the graft copolymers of the ABS resin recovered from a latex containing alkylarylsulfonate emulsifiers coagulating action of electrolytes, so that before coagulation of the latex was added the compound of formula RYx or R 0C0CH (S0 ^ X) CH ₂ C00R ₂ wherein R is an aliphatic alkyl or alkenyl and 8 to 20 C atoms, R 1 and R 2 are aliphatic alkyls having 4 to 12 C atoms, the total number of C atoms in the R 1 and R 1 alkyl being 8 to 24, X being Li, Na, K, NH 4; and Y is a sulfonate, sulfate or carboxyl group, in an amount of 20 to 300 wt. parts per 100 wt. parts of the alkylarylsulfonate emulsifiers present.

Graft copolymers of the ABS resin as used in this invention means a copolymer prepared by emulsion polymerizing one or more monomers, the polymer having a higher glass transition temperature T _{g of} 80 ° S) in the presence of the latex of elastomers with temperature T _g below 25 ° C . The most common cases of these polymers are the actual ABS polymers prepared by polymerizing a styrene-acrylonitrile mixture in the presence of an elastomeric latex based on butadiene homo- or copolymers. Further, they are similar copolymers based on styrene-acrylonitrile copolymer and elastomeric acrylates and similar polymers in which acrylonitrile is partially or completely replaced by methyl methacrylate.

Alkylarylsulfonate for the purposes of this invention means an alkali metal surface-active salt or an ammonium salt of alkylbenzenesulfonic acid, alkylnaphthalenesulfonic acid, polyalkylbenzeasulfonic acid or polyalkylnaphthalenesulfonic acid; the most common representatives of these are sodium dodecylbenzenesulfonate or sodium dibutylnaphthaleasulfonate, wherein the alkyls attached to the aromatic nucleus can be linear or branched. As a result of the production technology, these products are usually available in the form of mixtures whose components differ in the degree of alkylation and sulfonation. In a broader sense, the term also includes dispersants of the dinaphthyl methanesulfonic acid salt type.

The compounds of formula RYX are emulsifiers of the alkylsulfate, alkylsulfonate and aliphatic carboxylic acid salts, e.g. sodium dodecylsulfate, sodium dodecylsulfonate, potassium stearate, ammonium oleate. Usually, the conventional technical purity of commercial emulsifiers may be sufficient to achieve the desired effect, which may contain, in addition to the claimed ingredients, a number of impurities resulting from the use of imperfectly pure starting materials and side reactions in their synthesis.

The compound R ^OCOCHÍSOjXJCHgCOgRj is a dialkylsulfosuccinic acid salt; both R 1 -R 8 alkyls are typically the same in commercial products and contain 4 to 12 carbon atoms. The dispensing of these emulsifiers into the latex must be performed prior to the addition of the clotting agent (cell immediately or during the previous technological steps). A further reduction in the tpk value can be achieved by the simultaneous application of the procedures of cited AO 209 716.

The advantage of the process according to the invention is the possibility of coagulation at reduced temperature, which brings energy savings, allows for an increase in product quality, and in many cases also extends the range of applicability of the plant in terms of product range.

Example 1

The latex used to isolate the ABS polymer contained 28% dry matter. Its polymer contained 14% polybutadiene and 85% styrene acrylonitrile copolymer in a 75/25 weight ratio. To stabilize the latex particles, 1.5% sodium dodecylbenzenesulfanate, 0.1% sodium dibutylnaphthalenesulfonate, and 0.1% potassium dinaphthylmethane disulfonate were used in its synthesis. Coagulation was performed as described in AO 209 716. Calcium chloride as a 0.5% aqueous solution was used as the coagulating agent. The tpk value was 111 ° C, the coagulation temperature was 1.4 ° C. The resulting polymer was determined according to ČSN 64 0521 thermal resistance Vicat 12 ° C.

Example 2

The same latex was used to isolate the polymer as in Example 1, to which the wt. % of potassium stearate per polymer (i.e. 59% by weight of stearate to alkylarylsulfonate content) ... A coagulation temperature lower by 4 ° C, i.e. 110 ° C, was sufficient in this case to achieve a coagulate of similar properties to Example 1. C (tpk found 107 ° C). The heat resistance of Vicat, determined as in Example 1, was found to be 121 ° C.

Example 1 a d 3

The latex used to insulate the ABS polymer contained 25% dry matter. Its polymer contained 17 wt. polybutadiene and 83% styrene-alpha-methylstyrene-acrylonitrile copolymer in a weight ratio of 60/10/30. 0.5 wt.% Was used to stabilize the latex particles. % sodium dodecylbenzenesulfonate. In order to achieve similar properties of the coagulate as in Example 1, it was necessary to operate at a coagulation temperature of 1.9 ° C (tpk found 116 ° C) under otherwise identical conditions. The product has a heat resistance of Vicat 125 ° C.

Example 4

The same latex as in Example 3 was used to isolate the polymer, to which 1.5 wt. % potassium stearate per polymer (i.e. 300% by weight per dodecylbenzenesulfonate). In this case, a temperature of 05 ° C, i.e. 14 ° C higher (tpk found at 102 ° C) was sufficient to achieve a coagulate of similar quality to Example 3. The heat resistance of Vicat was found to be 124 ° C.

Example 5

A latex having a dry substance content of 30, whose polymer contained 20% by weight, was used to isolate the polymer. styrene-butadiene copolymer in a weight ratio of 10/90 to 80 wt. copolymer of styrene acrylonitrile in a weight ratio of 74/26. Sodium dodecylbenzessulfonate was present as an emulsifier in an amount of 0% by weight per polymer and sodium divaftylmentane disulfonate in an amount of 0.2% by weight. to polymer. A 0.5 ag> MgClg solution was used as a coagulating agent. To obtain a coagulate of similar quality to Example 1, temperatures of 113 ° C (tpk found at 110 ° C) had to be used, and the Vicat heat resistance value was determined to be 110 ° C. After addition of 1.2 wt. For the polymer (i.e., 100% by weight of alkylaryle sulfonate) of the sodium salt of alkylsulfoic acid (a technical mixture of individuals having 12 to 16 carbon atoms in the alkyl), a temperature 5 ° C lower, i.e. 108 ° C, was otherwise sufficient. The coagulation thermal threshold was found to be 05 ° C and the Vicat heat resistance value was 120 ° C.

When using sodium diamylsulfosuccinate and sodium lauryl sulfate in a 1/1 weight ratio instead of sodium alkylsulfonate and aluminum sulfate instead of MgClg, a temperature of 2 ° C lower, ie 106 ° C (tpk found 103 ° C, heat resistance Vicat 1.9 ° C) .

By comparing the tpk values for the procedures with the addition of reagents within the meaning of the invention (examples 2, 4, 5) and similar values without addition (examples 1, 3, 5), the possibility of decreasing the coagulation temperature while maintaining or insignificantly decreasing the heat resistance of the resulting polymer is obvious.

Claims (1)

OBJECT OF THE INVENTION A method for isolating graft copolymers of ABS type resin from latexes containing alkylarylsulfonate emulsifiers by electrolyte coagulation, comprising adding to the latex prior to coagulation a compound of the formula RYX or R ^OCOCHCCSOjXX ^COORg wherein R is an aliphatic alkyl or alkenyl of 8 to 20 ^{The C} atoms, R 1 and R g are aliphatic alkyls having 4 to 12 C atoms, the total number of C atoms in the R 1 and R 8 alkyls being 8 to 24, X is Li, Na, K, NH4 and Y are sulfonate, sulfate or carboxyl groups, in an amount of 20 to 300 parts by weight per 100 parts by weight. parts of the alkylarylsulfonate emulsifiers present.