SK279619B6 - Method of copolymer styrene-butylacrylate dispersion production - Google Patents

Abstract

An emulsive method of a copolymer dispersion production at low temperatures in an activator-comprising system, consisting of 0.06 - 0.2 weight parts of vitriol of iron heptahydrate and 0.12 - 0.25 weight parts of the disodium salt of ethylenediamine- -tetra acetic acid, 3.6 - 4.4 weight parts of ionic emulsifier, 4.3 - 6.6 weight parts non-ionic emulsifier and in the presence of a heterogeneous initiator. From 39.5 to 50 weight parts of styrene copolymerizes with 50 - 60.5 weight parts of butylacrylate simultaneously with 0.5 - 1.5 weight parts of acrylamide at a temperature of 30 - 50 degrees Celsius in the presence of water and monomers of the insoluble heterogeneous initiator represented by 5.1 to 23.5 weight parts of oxidated powdered isotactic polypropylene containing 0.14 - 0.19 weight parts of hydroperoxidic oxygen. The heterogeneous initiator is separated from the copolymer dispersion by means of a filtration after the polymerisation.

Description

Technical field

The invention relates to a process for the production of a copolymer of styrene-butyl acrylate dispersion having a low surface tension value, the films formed therefrom having a low water-absorption capacity and are resistant to solvents.

BACKGROUND OF THE INVENTION

In the prior art processes for the preparation of dispersions containing a copolymer of styrene with butyl acrylate, most often copolymerization was carried out in emulsion in the presence of ionic and nonionic emulsifiers. Most commonly used initiators were redox systems comprising an initiator predominantly potassium persulfate or ammonium persulfate and an activator predominantly sodium dithionite or sodium dithionate, which are dissolved in the aqueous phase of the polymerization system. In some cases, azoinitiators have been used. The polymerization temperature ranged from 30 ° C to 70 ° C. The emulsion copolymerization was carried out mostly in a batch or continuous manner.

Such a process for preparing styrene-butyl acrylate-containing dispersions has the disadvantage, inter alia, that the residues of the initiator system become part of the dispersion upon completion of the copolymerization. Their presence adversely affects the thermal and light stability of the dispersions, especially when using dispersions as a binder for water-borne anticorrosive paints. The use of a water-soluble initiator system can lead to the formation of coagulates, particularly in the case of batch emulsion copolymerization, which negatively affects the performance and application properties of the dispersion.

SUMMARY OF THE INVENTION

These disadvantages can be overcome according to the invention by a process for preparing a dispersion by copolymerization of styrene with butyl acrylate, which does not contain residues of the initiation system and coagulate, utilizing heterogeneously initiated emulsion copolymerization in a system comprising an activator of 0.12 to 0.25 parts by weight of disodium ethylenediamine tetraacetic acid disodium salt. up to 0.2 parts by weight of ferrous sulphate heptahydrate; and 4.3 to 6.6 parts by weight of a non-ionic and 3.6 to 4.4 ionic emulsifier, which consists in copolymerizing 39.5 to 50 parts by weight of styrene with 50 to 50 parts by weight. 60.5 parts by weight of butyl acrylate and 0.5 to 1.5 parts by weight of acrylamide at a temperature of 30 ° C to 50 ° C in the presence of a heterogeneous, water-insoluble and monomer-insoluble initiator which is an oxidized isotactic powdered polypropylene in an amount of 5.1 to 23 5 parts by weight per weight of monomers containing hydro peroxide oxygen of 0.14 to 0.19 weight percent, wherein the heterogeneous initiator is separated from the dispersion by filtration after copolymerization.

In the emulsion copolymerization of styrene with butyl acrylate, carried out in the presence of a heterogeneous initiator, this separate phase forms in the system in the form of a fine powder, which improves the mixing of the batch and prevents the formation of coagulates. This gives a homogeneous dispersion suitable as a binder for water-borne anticorrosive paints. The dispersion is characterized by a low surface tension in the range of 38.6 to 52.8 mN.m ^-1 . The films made therefrom are homogeneous with a low water absorption in the range from

12.5% to 17.0% in 24 hours and from 19.8% to 28.1% in ten days. In addition, the films are characterized by good resistance to organic solvents. The absence of initiator residues has a positive effect on improving the thermal and light stability of the dispersion itself, as well as the films formed therefrom.

The process for the preparation of water-dilutable dispersions of a styrene-butyl acrylate copolymer according to the invention is described in more detail in the following examples.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Into an inert atmosphere, 5.1 wt. 0.06 wt.% of oxidized powdered polypropylene (with an active oxygen content of 0.14%); 0.12 parts by weight of ferrous sulfate heptahydrate; parts by weight of the disodium salt of ethylenediaminetetraacetic acid (Chelaton III), 4.3 wt. parts by weight of the non-ionic emulsifier Slovasol 2430, which is essentially CH ₃ (C ₂ H ₄ O) ₂₉ C ₂ H ₄ OH, 3.6 wt. parts by weight of the ionic emulsifier Mersol 50 of the composition CH ₃ (CH ₂ ) ₁₄ SO ₃ Na, 50 wt. parts of purified butyl acrylate, 50 wt. parts of purified styrene and 111 wt. parts of water.

The contents of the vessel were heated to 30 ° C in an aqueous thermostate and simultaneously stirred at constant speed with an agitator under an inert atmosphere for four hours. After the polymerization is complete, the dispersion is separated from the heterogeneous initiator by filtration through a glass filter. The dispersion contains a 95% content of the PS / PBuAc copolymer after four hours of polymerization.

The surface tension of the dispersion is 40.2 mN.m ^-1 . The film formed from the dispersion is homogeneous. The water-absorption rate in 24 hours is 17.0% and in 10 days 28.1%.

Example 2

Into the polymerization vessel 20.5 wt. 0.1 parts by weight of oxidized powdered polypropylene (having an active oxygen content of 0.19%); % FeSO ₄ .7H ₂ O, 0.18 wt. parts of Chelaton III, 3.2 wt. parts of the ionic emulsifier Mersol 50, 5.6 non-ionic emulsifier Slovasol 2430,

39.5 wt. parts of purified styrene, 60.0 wt. 0.5 parts by weight of purified butyl acrylate; parts of purified acrylamide and 191.0 wt. parts of water.

The polymerization was carried out in the same manner as in Example 1. After four hours of polymerization at 50 ° C, the initiator was separated from the dispersion by filtration. The dispersion contained 98.5% of the copolymer component. Dispersion surface tension γ - 52.8 mN.m ^-1 . The film formed from a 200 µm dispersion has a water absorption of 12.5% in 24 hours and 20.1% in 10 days. The film was resistant to solvents: toluene, dioxane, MEK, dimethylsulfoxide and

N, N'-dimethylfluoramide.

Example 3

In an inert atmosphere 23.5 wt. parts of isotactic polypropylene powder (with a hydroperoxide oxygen content of 0,19%),

0.10 wt. % FeSO ₄ .7H ₂ O, 0.15 wt. parts by weight of Chelaton III, 2.2 wt. parts by weight of an ionic emulsifier of Mersol 50 and 3.6 of a nonionic emulsifier of Slovasol 2430, 25 wt. parts of purified styrene, 30 wt. parts of purified butyl acrylate and 170 wt. parts of water. After polymerization at 40 ° C for half an hour, a mixture of 0.10 wt.% Was added dropwise over three hours with constant stirring. % FeSO ₄ .7H ₂ O, 0.10 wt. parts of Che2 laton III, 2.2 wt. parts of the ionic emulsifier Mersol 50, 2.0 wt. parts of non-ionic emulsifier Slovasol 2430, 16 wt. parts of purified styrene, 22.5 wt. parts by weight of purified butyl acrylate, 1.5 wt. parts of acrylamide and 50 wt. parts of water. After the polymerization is complete, the initiator is filtered from the dispersion.

The content of the copolymer formed in the dispersion is 98.9%. Dispersion surface tension γ = 38.6 mN.m -1. A 200 µm film has a water absorption of 14.5% in 24 hours and 19.8% in 10 days. The films formed do not dissolve in the solvents mentioned in Example 2.

Industrial usability

The possibility of a technically undemanding separation of the initiator carrier with residual undigested peroxides from the dispersion makes it possible to obtain dispersions more resistant to the effects of heat and subsequent oxidation reactions. The dispersions obtained can be used as binders for water-borne anticorrosive paints. After formulation, the colors are characterized by good utility properties. Ingredients of paint do not settle, the paint is well-miscible. If the dispersion is thickened, it can be used as a sealant or as part of a dispersion adhesive.

From a technical point of view, the application of the invention does not require more economical modifications of the technological equipment.

Claims (1)

PATENT CLAIMS A process for the production of a styrene-butyl acrylate copolymer dispersion, characterized in that 39.5 to 50 parts by weight of styrene polymerizes and 50 to 50 parts by weight of styrene. 60.5 parts by weight of butyl acrylate at the same time as 0.5 to 0.5 1.5 parts by weight of acrylamide at a temperature of from 30 ° C to 50 ° C in an activator-containing system comprising 0.06 to 0.2 parts by weight of ferrous sulphate heptahydrate and 0.12 to 0.25 parts by weight of ethylenediaminetetraacetic acid disodium salt, 3.6 up to 4.4 parts by weight of an ionic emulsifier, 4.3 to 6.6 parts by weight of a non-ionic emulsifier in the presence of water and monomers of an insoluble heterogeneous initiator, which is an oxidized isotactic polypropylene in an amount of 5.1 to 23.5 parts by weight containing hydroperoxide oxygen 0 14 to 0.19% by weight, wherein the heterogeneous initiator is separated from the copolymer dispersion by filtration after polymerization.