Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1996-10-03
1997-12-16
Cain, Edward J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C08L 6700
Patent
active
056986254
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a process for the preparation of water-dilutable air-drying coating binders based on acrylic-modified and vinyl-modified alkyd resin emulsions and to their use in the formulation of oxidatively drying coating materials.
2. Description of Related Art
In EP 0267562 A2 (meth)acrylic and/or vinyl monomers containing no reactive groups other than the C--C double bond are polymerized in the presence of an aqueous solution of specific emulsifier resins, which may be alkyd resins, urethane-alkyd resins or epoxy resin esters.
Modified alkyd resins of similar composition are described in EP 0295403 A2, for the preparation of which, in addition to the conventional raw materials, specific fatty acid copolymers are used.
With the products obtained in accordance with EP 0267562 A2 and EP 0295403 A2 it is possible to a large extent to meet the technical coatings requirements of water-dilutable air-drying coating binders with respect to processability and film properties, but to formulate glossy top coats it is still necessary, albeit in small proportions, to use organic solvents, for example glycol ethers.
It has now been found that the alkyd resin emulsions prepared in accordance with EP 0295403 A2, if they additionally contain polyoxyalkylene groups introduced by way of specific (meth) acrylate monomers, are highly suitable, even without the use of "cosolvents", as binders for high-gloss top coats.
SUMMARY OF THE INVENTION
The invention relates accordingly to a process for the preparation of water-dilutable air-drying coating binders based on acrylic-modified and vinyl-modified alkyd resin emulsions, which process is characterized in that polyoxyalkylene groups, and containing no functional groups other than the C--C double bond of at least 95% by weight, and acids, for components a1) to a4) and, respectively, b1) to b5) necessarily being 100 in each case, with the proviso that in stage (B) components b2) to b5) are pre-esterified until a clear melt and an acid number of from 3 to 30 mg of KOH/g are reached, said alkyd resin (B), based on the solids content, having a content of from 30 to 70% by weight, preferably from 40 to 60% by weight, of unsaturated fatty acids, an intrinsic viscosity of from 8 to 15 ml/g (chloroform, 20.degree. C.) and an acid number of from 25 to 70 mg of KOH/g, and at least 80% of the corresponding carboxyl groups deriving from methacrylic acid units of the copolymer (A), and the modified alkyd resin (B) thus obtained is emulsified in water without the use of organic solvents.
The invention additionally relates to the use of the coating binders prepared according to this process in the formulation of water-dilutable coating materials which dry oxidatively at temperatures of up to 100.degree. C. and which, even without the addition of organic solvents, give coating films of very good gloss.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
For the preparation of the copolymer (A), the monomers are employed in the proportions indicated in the main claim.
The unsaturated fatty acids (component a1) used are fatty acids having an iodine number of greater than 135 preferably from 160 to 200) and having a predominantly insulated position of the double bonds. Suitable examples are linseed oil fatty acid and safflower fatty acid, if desired as a blend with up to 25% by weight of dehydrated castor oil fatty acid or of a comparable conjuene fatty acid prepared by isomerization.
As (meth) acrylate monomers containing polyoxyalkylene groups (component a3) it is possible to employ (meth)acrylate compounds containing at least three oxyalkylene groups and corresponding to the general structural formula to 45.
Typical examples of such compounds are esters of (meth)acrylic acid with ethylene glycol oligomers and/or propylene glycol oligomers, it being possible for the ethylene glycol and propylene glycol units to be arranged either randomly or in blocks.
The other (meth)acrylate monomers and/or vinyl monomers (component a4), which
Billiani Johann
Gobec Michael
Cain Edward J.
Vianova Resins Aktiengesellschaft
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