Polymeric materials and their use

Details Polymeric materials and their use Polymeric materials and their use

2000-08-09

2001-11-06

Yoon, Tae H. (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C523S200000, C523S206000, C524S504000, C525S064000, C526S271000

Reexamination Certificate

active

06313197

ABSTRACT:

This invention relates to polymeric stabilisers and to the formation of polymeric particles, i.e. particles having an external surface of organic polymer, which give improved stability when dispersed in a liquid, and to dispersions containing them.
WO97/24179 and WO97/24177 (PCT/GB96/03233 and PCT/GB96/03231) were not published at the first priority date of this application but describe various processes and products wherein a dispersion of polymer particles is formed in the presence of an amphipathic polymeric stabiliser in a non-aqueous medium, and then the particles are dispersed in an electrolyte, namely a detergent concentrate. The entire disclosure of those two publications and applications is herein incorporated by reference.
Those polymeric stabilisers are materials which are known for use in, for instance, reverse phase polymerisation processes, either reverse phase emulsion polymerisation or reverse phase bead polymerisation processes.
The requirement for effective stabilising properties in these very different media necessitates the provision of improved stabilisers suitable for such conditions of media.
Different types of dispersions are known from, for instance, GB-A-1,198,052, GB-A-1,231,614, GB-A-1,268,692, GB-A-2,207,681, AU-A-455,165, U.S. Pat. Nos. 3,580,880, 3,875,262, EP-A-707,018 and EP-A-719,085.
According to the invention, we provide novel polymeric amphipathic stabilisers. Amphipathic stabilisers are stabilisers which contain both hydrophobic groups and hydrophilic groups, both groups being present in amounts sufficient to allow the stabiliser to partition at the interface between aqueous and non-aqueous phases.
The novel stabilisers of the invention are addition polymers of hydrophobic monomer units and hydrophilic monomer units wherein the hydrophilic monomer units comprise carboxylic free acids or acid salt units and reactive monomer units selected from (a) glycidyl monomer units and (b) anhydride monomer units wherein the amount of anhydride monomer units is either below 10% by weight of total monomer units or is less than 19% by weight of total carboxylic acid monomer units.
Because the polymers are addition polymers of glycidyl or anhydride monomer units, the polymers have a polymeric backbone carrying the glycidyl or anhydride units as groups which are pendant to the backbone hydrocarbon chain and which are thus available for covalent reaction with other reactive groups. The monomers are all ethylenically unsaturated monomers.
The amount of the reactive monomer units is usually at least 0.5% and preferably at least 1% (by weight of total monomers). It may be at least 5%, for instance at least 10%. Usually it is not above 50% and most usually it is not above 30% by weight of total monomers. However best results are usually obtained with quite low amounts of the glycidyl or anhydride monomer, e.g, down to 0.5 or 1% and preferably not more than 5% or 10%. Amounts of 0.5 to 5%, often around 1 to 3%, are often preferred.
In use, the amphipathic polymer is reacted onto the polymeric particles in a dispersion, so as to stabilise the dispersion. We believe that the use of the preferred low amounts of reactive groups is desirable because it allows the stabilisers to be permanently attached to the particles at points which are, on a molecular scale, spaced far apart. This results in the other units of the polymeric stabiliser being able to adopt their normal configuration with respect to the particles and, in particular, it allows for appropriate spacing of the hydrophobic units and the hydrophilic units, and it allows for appropriate steric displacement of the units relative to one another and from particles. If the amount of reactive units in the stabiliser is too high then there is a tendency for the stabiliser to be bonded, on a molecular scale, at such closely spaced points around the particles that the effectiveness of the stabiliser is inhibited.
The glycidyl monomer can be any ethylenically unsaturated glycidyl derivative, whereby the ethylenically unsaturated moiety polymerises into the backbone of the polymer and the glycidyl group is pendant.
The glycidyl derivative can be glycidyl acrylate but is preferably glycidyl methacrylate.
When the reactive groups are anhydride monomer units, they are anhydride groups of dicarboxylic acid monomers, for example maleic acid. They can be introduced by copolymerisation of maleic anhydride with other monomers such as maleic acid or other carboxylic acid, or they can be introduced by polymerisation of maleic anhydride or other anhydride monomer followed by hydrolysis of some of the groups. The extent of hydrolysis is preferably high, so that the amount of maleic anhydride or other anhydride groups is less than 19% and preferably less than 15 or 17%, of the total carboxylic acid monomer units.
We have described in, for example, British applications GB 9713812.7 and 9713310.1 on Jun. 30th 1997 and in PCT applications filed even date herewith claiming priority from those and carrying references PRL03819WO and PRL03821WO certain processes utilising stabilisers containing anhydride groups, and it is mentioned therein that the stabiliser may be derived by hydrolysis of 20 to 80% of the carboxylic acid monomer units.
The other monomers in the stabiliser are preferably one or more hydrophobic monomers such as C
1-4
or other lower alkyl acrylate or methacrylate (preferably methyl methacrylate) and, especially, fatty alkyl acrylate or methacrylate, or styrene or an alkyl styrene. The fatty alkyl group can be C
8-32
, often C
10-24
and preferably C
12-18
. Any of the hydrophobic monomers conventionally used in amphipathic stabilisers for reverse phase polymerisation may be used in the invention.
The total amount of hydrophobic monomer is usually 30 or 40% up to 70 or 80%, often 40-60%. by weight of monomers. The amount of fatty alkyl methacrylate is often 20-50% by weight of total monomers, the remaining hydrophobic monomer preferably being 0-50%, often 10-40%, methyl methacrylate.
The hydrophilic monomers which may be used may be ionisable monomers such as ethylenically unsaturated carboxylic acids, such as acrylic acid or, especially, methacrylic acid. Instead of or in addition to using acrylic or methacrylic acid as hydrophilic monomer, a carboxylic acid such as maleic acid (either as the free acid or as the anhydride) may be used. Some or all of the hydrophilic monomer may be a non-ionisable hydrophilic monomer. Preferably the non-ionisable monomer is an ethylenically unsaturated hydroxyalkyl monomer, e.g., a hydroxyalkyl ester of an ethylenically unsaturated acid such as acrylic or methacrylic acid. The hydroxyalkyl group is preferably a C
1-8
(usually C
2-4
) hydroxyalkyl group such as hydroxyethyl or, preferably, hydroxypropyl. Preferably it is present as the methacrylate ester.
The total amount of hydrophilic monomer may be within the ranges typically used in amphipathic polymeric stabilisers for reverse phase polymerisation processes, and may be as described in the aforementioned PCT publications. For instance the total amount of ethylenically unsaturated carboxylic acid monomer is generally at least 5% by weight but usually not above 30% or 40% by weight. The total amount of ethylenically unsaturated carboxylic acid monomer and glycidyl monomer is generally in the range 5 to 70%, preferably 10 or 20% up to 40 or 50% by weight of monomers.
When hydroxyalkyl monomer is used, the total amount of hydrophilic monomer may be in the ranges given above for carboxylic acid plus glycidyl monomers. Preferably the amount of hydroxyalkyl monomer is 1 to 40%, often 3-20%, by weight of the monomers. If it is used in conjunction with little or no carboxylic monomer (e.g., below 10%), the amount of hydroxyalkyl monomer may be 10 or 15% up to 40%. The hydrophilic monomer component may be a mixture of methacrylic acid and hydroxypropyl (meth) acrylate in a weight ratio of 15:1 to 1:5, often 8:1 to 1:1. For instance there may be 15-30% methacrylic acid and 2-10% hydroxypropyl methacrylate.
Reference should be made to WO97/2417

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