Process for producing aqueou dispersions

• US 20060052515A1
• Filed: 10/18/2003
• Published: 03/09/2006
• Est. Priority Date: 12/19/2002
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: Roehm GmbH & Co. KG
• Inventors: Schultes, Klaus, Schikowsky, Hartmut, Mueller, Reiner, Hoess, Werner, Suefke, Thomas
• Granted Patent: US 8,119,734 B2
• Time in Patent Office: Days
• US Class Current: 524/556
• CPC Class Codes: C08F 220/12 of monohydric alcohols or phenols
• CPC Class Codes: C08F 285/00 Macromolecular compounds obtained by polymerising monomers on to preformed graft polymers
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 2666/24 Graft or block copolymers according to groups C08L51/00, C08L53/00 or C08L55/02; Derivatives thereof
• CPC Class Codes: C08L 33/10 Homopolymers or copolymers of methacrylic acid esters
• CPC Class Codes: C08L 33/12 Homopolymers or copolymers of methyl methacrylate
• CPC Class Codes: C08L 33/20 Homopolymers or copolymers of acrylonitrile C08L55/02 takes precedence
• CPC Class Codes: C08L 35/06 Copolymers with vinyl aromatic monomers
• CPC Class Codes: C08L 51/003 grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds C08L51/04, C08L51/06 take precedence
• CPC Class Codes: C08L 55/005 Homopolymers or copolymers obtained by polymerisation of macromolecular compounds terminated by a carbon-to-carbon double bond
• CPC Class Codes: C09D 133/10 Homopolymers or copolymers of methacrylic acid esters
• CPC Class Codes: Y10T 428/2998 including synthetic resin or polymer

Abstract

The present invention relates to a process for preparing an aqueous dispersion, by a) forming an initial charge from water and emulsifier, b) adding from 25.0 to 45.0 parts by weight of a first composition comprising A) from 50.0 to 99.9 parts by weight of alkyl methacrylates, B) from 0.0 to 40.0 parts by weight of alkyl acrylates, C) from 0.1 to 10.0 parts by weight of crosslinking monomers and D) from 0.0 to 8.0 parts by weight of styrenic monomers and polymerizing, c) adding from 35.0 to 55.0 parts by weight of a second composition comprising E) from 80.0 to 100.0 parts by weight of (meth) acrylates F) from 0.05 to 10.0 parts by weight of crosslinking monomers and G) from 0.0 to 20.0 parts by weight of styrenic monomers, and polymerizing, d) adding from 10.0 to 30.0 parts by weight of a third composition comprising H) from 50.0 to 100.0 parts by weight of alkyl methacrylates, I) from 0.0 to 40.0 parts by weight of alkyl acrylates and J) from 0.0 to 10.0 parts by weight of styrenic monomers and polymerizing. Features of the process are that e) each polymerization is carried out at a temperature in the range from >60 to <90° C. and f) the relative proportions of all of the substances are selected in such a way that the total weight of components A) to J), based on the total weight of the aqueous dispersion, is greater than 50.0% by weight.

Claims

1. A process for preparing an aqueous dispersion, comprising

a) forming an initial charge with water and an emulsifier,

b) adding from 25.0 to 45.0 parts by weight of a first composition comprising

A) from 50.0 to 99.9 parts by weight of alkyl methacrylates having from 1 to 20 carbon atoms in the alkyl radical,

B) from 0.0 to 40.0 parts by weight of alkyl acrylates having from 1 to 20 carbon atoms in the alkyl radical,

C) from 0.1 to 10.0 parts by weight of crosslinking monomers and

D) from 0.0 to 8.0 parts by weight of styrenic monomers of the general formula (I)

 

where each of the radicals R¹ to R⁵, independently of the others, is hydrogen, a halogen, a C_1-6-alkyl group or a C_2-6-alkenyl group, and the radical R⁶ is hydrogen or an alkyl group having from 1 to 6 carbon atoms,

and polymerizing to a conversion of at least 85.0% by weight, based on the total weight of components A), B), C) and D),

c) adding from 35.0 to 55.0 parts by weight of a second composition comprising

E) from 80.0 to 100.0 parts by weight of (meth)acrylates

F) from 0.05 to 10.0 parts by weight of cross-linking monomers and

G) from 0.0 to 20.0 parts by weight of styrenic monomers of the general formula (I),

and polymerizing to a conversion of at least 85.0% by weight, based on the total weight of components E), F) and G),

d) adding from 10.0 to 30.0 parts by weight of a third composition comprising

H) from 50.0 to 100.0 parts by weight of alkyl methacrylates having from 1 to 20 carbon atoms in the alkyl radical,

I) from 0.0 to 40.0 parts by weight of alkyl acrylates having from 1 to 20 carbon atoms in the alkyl radical and

J) from 0.0 to 10.0 parts by weight of styrenic monomers of the general formula (I)

and polymerizing to a conversion of at least 85.0% by weight, based on the total weight of components H), I) and J),

where the parts by weight given for the compositions b), c) and d) give a total of 100.0 parts by weight,

wherein

e) each polymerization is carried out at a temperature in the range from above 60 to below 90°

C. and

f) the relative proportions of all of the substances are selected in such a way that the total weight of components A) to J), based on the total weight of the aqueous dispersion, is greater than 50.0% by weight.

2. The process according to claim 1, wherein an aqueous dispersion is prepared which comprises less than 5.0% by weight of coagulate, based on its total weight.

3. The process according to claim 1, wherein 90.00 to 99.99 parts by weight of water and from 0.01 to 10.00 parts by weight of emulsifier are used to form an initial charge, where the parts by weight given give a total of 100.00 parts by weight.

4. The process according to claim 1, wherein an anionic or non-ionic emulsifier is utilized.

5. The process according to claim 1, wherein an aqueous emulsion which comprises a seed latex is used to form an initial charge.

6. The process according to claim 5, wherein a seed latex whose particle radius, measured by the Coulter method, is in the range from 5.0 to 20.0 nm is used to form an initial charge.

7. The process according to claim 1, wherein an aqueous emulsion which comprises an alkyl alcohol having from 12 to 20 carbon atoms in the alkyl radical is used to form an initial charge.

8. The process according to claim 1, wherein the polymerization in steps b) to d) is initiated with a peroxodisulphate.

9. The process according to claim 1, wherein the relative proportions of all of the substances are selected in such a way that core-shell particles are obtained with an overall radius, measured by the Coulter method, in the range from 150.0 to less than 250.0 nm.

10. The process according to claim 1, wherein the second and the third monomer mixture are metered in as required by consumption.

11. A core-shell particle obtained by a process according to claim 1.

12. A moulding composition comprising, based in each case on its total weight:

A) from 1.0 to 50.0% by weight of at least one core-shell particle according to claim 11;

B) from 1.0 to 99.0% by weight of at least one (meth)acrylic polymer,

C) from 0.0 to 45% by weight of styrene-acrylonitrile polymers, and

D) from 0.0 to 10.0% by weight of other additives

where the percentages by weight give 100.0% by weight in total.

13. The moulding composition according to claim 12, wherein the (meth)acrylic polymer encompasses, based in each case on its total weight,

a) from 50.0 to 100.0% by weight of alkyl methacrylate repeat units having from 1 to 20 carbon atoms in the alkyl radical,

b) from 0.0 to 40.0% by weight of alkyl acrylate repeat units having from 1 to 20 carbon atoms in the alkyl radical and

c) from 0.0 to 8.0% by weight of styrenic repeat units of the general formula (I),

where the percentages by weight give 100.0% by weight in total.

14. The moulding composition according to claim 12, wherein the moulding composition comprises styrene-acrylonitrile copolymers, where the styrene-acrylonitrile copolymers were obtained by polymerizing any mixture which is composed of

from 70 to 92% by weight of styrene

from 8 to 30% by weight of acrylonitrile and

from 0 to 22% by weight of other comonomers, based in each case on the total weight of the monomers to be polymerized.

15. The moulding composition according to claim 12, wherein the moulding composition it comprises, based on its total weight, from 0.1 to 10.0% by weight of another polymer whose weight-average molecular weight is higher by at least 10% than that of the (meth)acrylic polymer.

16. A moulding obtained from a moulding composition according to claim 12.

17. The moulding according to claim 16, wherein the moulding has a Vicat softening point ISO 306 (B50) of at least 85, preferably at least 90 and particular preferably at least 93°

C., a notched impact strength NIS (Charpy 179/1eA) to ISO 179 of at least 6.0 kJ/m² at 23°

C. and of at least 2.5 kJ/m² at −

10°

C., a modulus of elasticity to ISO 527-2 of at least 1500 Pa s, a haze to ASTM D 1003 (1997) of at most 2.5%, a transmittance (D 65/10°

) to DIN 5033/5036 of at least 88.5%.

18. The process according to claim 8 wherein the peroxidisulphate is ammonium and/or alkali metal peroxodisulphate.

19. A core-shell particle obtained by a process according to claim 6.