EP2411420A1

EP2411420A1 - Use of nonionic surfactants as emulators for the emulsion polymerization (iii)

Info

Publication number: EP2411420A1
Application number: EP10709968A
Authority: EP
Inventors: Markus Scherer; Thomas Schliwka; Katharina Hömberg; Uwe Held; Thomas Mausberg; Ronald Klagge
Original assignee: Cognis IP Management GmbH
Current assignee: Cognis IP Management GmbH
Priority date: 2009-03-24
Filing date: 2010-03-13
Publication date: 2012-02-01
Also published as: EP2239276A1; JP5722303B2; US20120029131A1; WO2010108613A1; US8779075B2; JP2012521444A

Abstract

The invention relates to the use of aqueous solutions of nonionic surfactants as gel phase free emulator systems for the emulsion polymerization, wherein said nonionic surfactants are chosen from the group (a) of the addition products from 1 to 40 mol ethylene and/or propylene oxide per mol of allyl alcohol, and (b) of the addition products from 1 to 40 mol ethylene and/or propylene oxide per mol of allyl alcohol, wherein the OH-group of said addition products is end-capped in the sense that it is substituted by a group OR, wherein R is an alkyl group with 1 to 20 C-atoms, which can be saturated or unsaturated, straight chained or branched.

Description

5> Use of Nonionic Surfactants as Emulsifiers for Emulsion Polymerization (III) "

Field of the invention

The invention relates to the use of special surfactants as emulsifiers for emulsion polymerization, furthermore to the polymer dispersions preparable using these surfactants and to a process for preparing these polymer dispersions.

State of the art

Emulsion polymerization is a special process of polymerization in which low-water-soluble monomers are emulsified in water with the aid of emulsifiers and polymerized using water-soluble initiators such as potassium peroxodisulfate or redox initiators. Anionic and / or nonionic surfactants are the essential ingredients here. By means of the micellar structure in the aqueous solution, they ensure the process of emulsion polymerization.

In the course of emulsion polymerization processes, surfactants are often diluted with water or incorporated into an aqueous reaction solution; the surfactants are then present in the concentration required for the emulsion polymerization process. The surfactants generally undergo a wide concentration range, especially if they are previously present as 100% systems, ie anhydrous. Frequently, this works in the temperature range around 25 ° C. Many surfactants show a miscibility gap with water, depending on the temperature and the concentration. This means that they are not soluble in water there, as evidenced by the formation of an insoluble gel block that prevents immediate further processing of the reaction mixture. This is an extremely undesirable process. Description of the invention

It is an object of the present invention to provide aqueous surfactant solutions which are suitable as gel phase-free emulsifier systems for emulsion polymerization. In other words, the central task to be solved by the emulsifier systems to be developed has been to effectively prevent the appearance of gel phases caused by the addition of surfactants or aqueous surfactant solutions in the course of emulsion polymerization processes.

The use of such emulsifier systems in the emulsion polymerization should, moreover, be associated with only little coagulum formation.

The present invention is first the use of aqueous solutions of nonionic surfactants as gel phase emulsifier systems for emulsion polymerization, wherein the nonionic surfactants selected from the group (a) the addition products of 1 to 40 moles of ethylene and / or propylene oxide per mole of allyl alcohol, and

(B) the addition products of 1 to 40 moles of ethylene and / or propylene oxide per mole of allyl alcohol, wherein the OH group of these addition products is end-capped in the sense that it is replaced by a group OR, wherein R is a Alkyl radical having 1 to 20 carbon atoms, which may be saturated or unsaturated, straight-chain or branched.

Surprisingly, it has been found that the nonionic surfactants selected from the group (a) of the adducts of 1 to 40 moles of ethylene and / or propylene oxide per mole of allyl alcohol, and

(B) the addition products of 1 to 40 moles of ethylene and / or propylene oxide per mole of allyl alcohol, wherein the OH group of these addition products is end-capped in the sense that it is replaced by a group OR, wherein R is a Alkyl radical having 1 to 20 C atoms, which may be saturated or unsaturated, straight-chain or branched, characterized in that their aqueous solutions are gel phase-free. Therefore, these nonionic surfactants or their aqueous surfactant concentrates can be diluted with water as desired without gel phases and thus water-insoluble gel blocks occurring in certain concentration ranges.

With regard to the use of aqueous solutions of nonionic surfactants as gel phase emulsifier systems for emulsion polymerization, wherein the nonionic surfactants are selected from groups (a) and (b) as defined above:

In a preferred embodiment, the surfactants are selected exclusively from the compounds of class (a).

In a further preferred embodiment, the surfactants are selected exclusively from the compounds of class (b).

In a further preferred embodiment, the surfactants are selected exclusively from both the compounds of class (a) and the compounds of class (b), that is to say, the emulsifiers used are exclusively mixtures of compounds (a) and (b).

A further subject of the present invention is a process for the preparation of aqueous latices by emulsion polymerization, aqueous solutions of nonionic surfactants being used as gel-phase-free emulsifier systems in the course of emulsion polymerization, the nonionic surfactants being selected from group (a) of the adducts of 1 to 40 moles of ethylene oxide and / or propylene oxide per mole of allyl alcohol, and (b) the adducts of 1 to 40 moles of ethylene oxide and / or propylene oxide per mole of allyl alcohol, the OH group of these addition products being end group-capped in the sense that that it is replaced by a group OR, where R is an alkyl radical having 1 to 20 C atoms, which may be saturated or unsaturated, straight-chain or branched. In one embodiment of the inventive method as emulsifiers in addition to one or more surfactants from the group of compounds (a) and (b) as further emulsifiers additionally one or more surfactants, which are selected from the group

(c) the compounds of the formula R'-OXR ² , where X is a segment which is composed of 1 to 40 mutually linked ethylene and / or propylene oxide units and in which the radicals R 1 and R 2 independently of one another are alkyl radicals having 1 to 20 C Represent atoms which may each be saturated or unsaturated, straight-chain or branched, with the proviso that the radicals R ¹ and R ^{2 are} not allyl radicals,

(d) the compounds of the formula R ³ -OXH, where X is a segment which is composed of 1 to 40 ethylene and / or propylene oxide units linked together and in which R ³ is an alkyl radical having 1 to 20 C atoms, the seeded may be unsaturated or unsaturated, straight or branched, with the proviso that

R ^{3 is} not an allyl radical, and

(E) the compounds of formula H-O-X-H, wherein X is a segment that is composed of 1 to 40 linked together ethylene and / or propylene oxide units.

The compounds (a) to (e) each contain a segment which is composed of 1 to 40 linked ethylene oxide units (EO) and / or propylene oxide units (PO). This segment can be constructed either exclusively EO or exclusively from PO units. But it is also possible that it consists of both EO and PO units; in this case, the EO or PO units may be statically distributed or block by block. The synthesis of the compounds (a) to (e) can be carried out by methods known to those skilled in the art. In particular, the usual techniques of ethoxylation or propoxylation apply to the introduction of the EO / PO segments: these are generally carried out at elevated temperatures. and elevated pressure in the presence of suitable alkoxylation catalysts. The choice of the alkoxylation catalyst influences the so-called homolog distribution. Thus, a broad homolog distribution is achieved in the presence of the catalytically active alkali metal alcoholates, such as sodium ethylate, while, for example, in the presence of hydrotalcite as the catalyst, a strongly narrowed homolog distribution (so-called "narrow range" products) is achieved.

To the compounds (a)

The compounds (a) are adducts of 1 to 40 moles of ethylene and / or propylene oxide per mole of allyl alcohol.

To the compounds (b)

The compounds (b) are adducts of 1 to 40 moles of ethylene and / or propylene oxide per mole of allyl alcohol, wherein the OH group of these addition products is end-capped in the sense that it is replaced by a group OR, wherein R is an alkyl radical having 1 to 20 C atoms, which may be saturated or unsaturated, straight-chain or branched.

To the compounds (c)

The compounds (c) are compounds of the formula R'-OXR ² , wherein X is a segment which is composed of 1 to 40 ethylene oxide and / or propylene oxide units linked together and in which the radicals R ¹ and R ² independently - gig each other alkyl radicals having 1 to 20 carbon atoms, each of which may be saturated or unsaturated, straight-chain or branched, with the proviso that the radicals R ¹ and R ^{2 are} not allyl radicals. To the compounds (d)

The compounds (d) are compounds of the formula R ³ -OXH, where X is a segment which is made up of 1 to 40 mutually linked ethylene and / or propylene oxide units and wherein R ^{3 is} an alkyl radical having 1 to 20 C Atom, which may be saturated or unsaturated, straight-chain or branched, with the proviso that R ^{3 is} not an allyl radical.

Compounds (e) Compounds (e) are compounds of the formula H-O-X-H, wherein X is a segment made up of 1 to 40 ethylene and / or propylene oxide units linked together.

The compounds from group (a) and (b) to be used according to the invention, if desired in combination with compounds from group (c), (d) and (e), can be used as sole emulsifiers (primary emulsifiers) in emulsion polymerization. However, it is also possible to use them together with one or more anionic, cationic or (other, different from the compounds (a) to (e)) nonionic emulsifiers.

In a preferred embodiment, the nonionic emulsifiers according to the invention are used in combination with anionic emulsifiers, in particular those selected from the group of known fatty alcohol sulfates, fatty alcohol ether sulfates, sulfosuccinates, alkylaryl sulfonates, alkylaryl ether sulfates, alkyl sulfates, fatty acid sulfonates, phosphate esters, olefin sulfates, Alkanesulfonates, α-sulfomonocarboxylic acid esters.

The emulsifiers to be used in the course of the process according to the invention

Group (a) and (b) - if desired in combination with compounds from the group (c), (d) and (e) - are - if they are during the emulsion polymerization be added - in an amount of 0.5 to 10 wt .-%, preferably from 1 to 5 wt .-% and in particular from 1 to 3 wt .-% - the wt .-% - are in each case based on the total amount the monomers used in the emulsion polymerization - used.

However, it may also be desired to carry out the emulsion polymerization in the presence of other emulsifiers, which are selected in particular from the group of nonionic and / or anionic surfactants, and one or more emulsifiers of group (a) and (b) - if desired in combination with compounds of the group (c), (d) and (e) - to meter only after completion of the polymerization of the finished latices, where they then act in the sense of a Nachstabilisierung the aqueous latices.

In a further embodiment, the compounds of group (a) and (b) - if desired in combination with compounds from group (c), (d) and (e) - both during the emulsion and after the emulsion polymerization. It may be desirable to use the compounds of group (a) and (b) - if desired in combination with compounds from group (c), (d) and (e) - in mixture with other surfactants or as sole surfactants. In a variant, the emulsion polymerization is started in the presence of classical anionic surfactants or mixtures of classical anionic and nonionic surfactants and then one or more emulsifiers of group (a) and (b) - if desired in combination with compounds from group (c), (i ) and (e) - toward the end of the emulsion polymerization and additionally after completion of the polymerization; in this variant, the emulsifiers of group (a) and (b) - if desired in combination with compounds from group (c), (d) and (e) - on the one hand as emulsifiers during the emulsion and on the other in the sense of a post-stabilization the aqueous latices.

For the purpose of subsequent stabilization, the compounds of group (a) and (b) are used, if desired, in combination with compounds from group (c), (d) and (e), irrespective of whether they are already used during the emulsion polymerization in an amount of 0.1 to 10 wt .-%, preferably from 0.1 to 5 wt .-% and in particular from 0.1 to 3 wt .-% - the wt .-% - information is in each case to the total amount of monomers used in the emulsion polymerization - a.

The nature of the polymers and copolymers in the aqueous latices is not particularly limited per se. However, polymers or copolymers based on the following monomer units are particularly preferred: acrylic acid, acrylic acid esters, butadiene, methacrylic acid, methacrylic acid esters, styrene, vinyl acetate and vinyl versatate.

A further subject of the invention are aqueous polymer dispersions obtainable by the process according to the invention described above.

B e i s p e e l e

Substances used:

FA-30EO: addition product of 30 mol of ethylene oxide onto a fatty alcohol (Disponil LS 30, Cognis)

Breox I: ethylene oxide adduct of allyl alcohol (Breox AA E 450 H, Fa.

Cognis)

Disponil AFX 3070: modified ethoxylated fatty alcohol (Cognis)

Example 1 (according to the invention)

A surfactant mixture was prepared by mixing the following components: 455 g FA-30EO and 195 g Breox I. The active substance content of the mixture was 100%. To test the gel behavior, the surfactant mixture according to the invention was continuously diluted with demineralized water at 25.degree. C. until its concentration was 30%. During the entire dilution process, no gel phases occurred, i. the surfactant mixture remained completely dissolved in water; the aqueous solution showed no inhomogeneities. At the concentrations given in Table 1, one sample each was taken and slowly cooled in a temperature bath until its pour point was reached. Table 1 shows the relationship between concentration K and pour point S.

Table 1

Example 2 (for comparison)

300 g of Disponil AFX 3070 were diluted according to the procedure in Example 1 in the concentration range of 65% to 35% with demineralized water. In the At the concentrations indicated in Table 2, a sample was taken and analyzed for pour point as described in Example 1. Table indicates the corresponding pour points. In the concentration range of about 60% to about 40%, the solution shows a miscibility gap, which was evident by the appearance of a gel block.

Table 2

Properties of the latices

The use of the emulsifiers according to Example 1 had no negative effects on the properties of the latexes produced in their use in the emulsion polymerization. This was independent of the nature of the monomers used for the polymerization - in particular acrylate, styrene / acrylate and VeoVa monomer systems were tested.

Furthermore, it has been observed that the polymer dispersions prepared using the surfactant mixtures according to the invention have an increased shear stability.

Claims

claims

1. Use of aqueous solutions of nonionic surfactants as gel-free emulsifier systems for the emulsion polymerization, the nonionic surfactants being selected from the group

(A) the addition products of 1 to 40 moles of ethylene and / or propylene oxide per mole of allyl alcohol, and

(B) the addition products of 1 to 40 moles of ethylene and / or propylene oxide per mole of allyl alcohol, wherein the OH group of these addition products is end-capped in the sense that it is replaced by a group OR, wherein R is an alkyl radical having 1 to 20 C atoms, which may be saturated or unsaturated, straight-chain or branched.

2. A process for the preparation of aqueous latices by emulsion polymerization, being used in the course of emulsion polymerization aqueous solutions of nonionic surfactants as gel phase emulsifier systems, wherein the nonionic surfactants selected from the group (a) of the adducts of 1 to 40 moles of ethylene and / or propylene oxide per mole of allyl alcohol, and (b) the adducts of from 1 to 40 moles of ethylene and / or propylene oxide per mole of allyl alcohol, wherein the OH group of these adducts is end-capped in the sense that it is replaced by a group OR, wherein R is an alkyl radical having 1 to 20 C atoms, which may be saturated or unsaturated, straight-chain or branched.

3. The method of claim 2, wherein additionally used as emulsifiers one or more surfactants which are selected from the group

(c) the compounds of the formula R'-OXR ² , where X is a segment which is composed of 1 to 40 mutually linked ethylene and / or propylene oxide units and in which the radicals R ¹ and R ^{2 are} independently of one another kylreste with 1 to 20 carbon atoms, which may be in each case saturated or unsaturated, straight-chain or branched, with the proviso that the radicals R ¹ and R ^{2 are} not allyl radicals,

(d) the compounds of the formula R ³ -OXH. where X is a segment which is composed of 1 to 40 linked ethylene and / or propylene oxide units and wherein R3 is an alkyl radical having 1 to 20 C atoms, which may be saturated or unsaturated, straight-chain or branched, with the proviso in that R3 is not an allyl radical, and

(e) the compounds of the formula H-O-X-H, where X is a segment which is made up of 1 to 40 mutually linked ethylene and / or propylene oxide units.

4. The method of claim 2 or 3, wherein as emulsifiers additionally one or more surfactants used, which are selected from the group of anionic, cationic and nonionic surfactants, wherein the non-ionic surfactants of the compounds (a) to (e) are different ,

5. The method according to any one of claims 2 to 4, wherein the surfactants from the groups (a) and (b) used during the emulsion polymerization and / or added to the latexes for subsequent stabilization after the emulsion polymerization.

6. The method according to any one of claims 2 to 5, wherein the monomers used in the emulsion polymerization selected from the group consisting of acrylic acid, acrylic acid esters, butadiene, methacrylic acid, methacrylic acid esters, styrene, vinyl acetate and vinyl versatate.

7. Polymer dispersions obtainable by the process according to one of claims 2 to 6.