Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
1999-06-17
2002-02-26
Thibodeau, Paul (Department: 1773)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C428S457000, C428S461000, C428S522000, C522S182000, C427S496000, C427S508000
Reexamination Certificate
active
06350523
ABSTRACT:
The invention relates to the use of radiation-curable compositions comprising from 5 to 100% by weight, based on the overall amount of radiation-curable compounds, of carbonate (meth)acrylates as coating compositions for exterior applications.
Radiation-curable compositions have to date been used predominantly for the coating of wood, paper and plastics in the interior sector. Exterior applications require resistance to the effects of weathering, which for example means low yellowing tendency, stability to hydrolysis, mechanical stability under weathering conditions, especially stability to cracking, and also acid and other chemical resistance.
In addition to the required weathering stability there is a desire for good processing properties, such as minimal odor nuisance and high reactivity, and also good mechanical properties in the resultant coatings, such as high flexibility and hardness.
Radiation-curable compositions known to date, as disclosed for example by JP 62-132570 and WO 92/17337, do not go far enough toward meeting the above requirements.
EP-A-92 269 and DE-A-27 57 086 disclose carbonate (meth)acrylates. Exterior applications are not described.
It is an object of the present invention to provide weathering-resistant, radiation-curable compositions for exterior applications, having high weathering stability, good processing properties and, at the same time, good mechanical properties.
We have found that this object is achieved by the use of the above compositions.
The radiation-curable compositions contain from 0.5 to 100% by weight, preferably from 5 to 80% by weight and, with particular preference, from 10 to 50% by weight of carbonate (meth)acrylates. These percentages by weight are based on the sum of radiation-curable compounds.
The carbonate (meth)acrylates contain on average preferably from 1 to 5, in particular from 1 to 3, and, with particular preference, 2 or 3 carbonate groups.
The carbonate (meth)acrylates contain on average preferably from 1 to 5, in particular from 2 to 4 and, with particular preference, 2 or 3 (meth)acrylic groups, and with very particular preference 2 (meth)acrylic groups.
The number-average molecular weight M
n
of the carbonate (meth)acrylates is preferably less than 3000 g/mol, with particular preference less than 1500 g/mol and, with very particular preference, less than 800 g/mol (as determined by gel permeation chromatography using polystyrene as standard and tetrahydrofuran as solvent).
The carbonate (meth)acrylates are readily obtainable by transesterifying carbonic esters with polyhydric, preferably dihydric, alcohols (diols, such as hexanediol) and subsequently esterifying the free OH groups with (meth)acrylic acid or else by a transesterification with (meth)acrylic esters, as is described, for example, in EP 92 269. They can also be obtained by reacting phosgene, urea derivatives with polyhydric alcohols, such as dihydric alcohols, for example.
Particularly preferred carbonate (meth)acrylates are those of the formula:
where R
1
is H or CH
3
, X is a C
2
-C
18
alkylene group and n is an integer from 1 to 5, preferably from 1 to 3.
R
1
is preferably H, and X is preferably C
2
-C
10
alkylene, with particular preference C
4
-C
8
alkylene. With very particular preference, X is C
6
alkylene.
These compounds are preferably aliphatic carbonate (meth)acrylates.
In addition to the carbonate (meth)acrylates the radiation-curable composition may include further radiation-curable compounds.
Particularly suitable are urethane (meth)acrylates, epoxy (meth)acrylates and melamine (meth)acrylates.
Urethane (meth)acrylates, for example, are obtainable by reacting polyisocyanates with hydroxyalkyl (meth)acrylates with or without chain extenders such as diols, polyols, diamines, polyamines or dithiols or polythiols. Urethane acrylates which can be dispersed in water without the addition of emulsifiers additionally comprise ionic and/or nonionic hydrophilic groups, which are introduced into the urethane acrylate by means, for example, of structural components such as hydroxycarboxylic acids.
The urethane (meth)acrylates preferably have a number-average molecular weight M
n
of from 500 to 20,000, in particular from 750 to 10,000 and, with particular preference, from 750 to 3000 g/mol (as determined by gel permeation chromatography using polystyrene as standard).
The urethane (meth)acrylates preferably have a content of from 1 to 5, with particular preference from 2 to 4, mols of (meth)acrylic groups per 1000 g of urethane (meth)acrylate.
Preferred structural components of the urethane (meth)acrylates are
C
1
-C
8
-hydroxyalkyl (meth)acrylates,
C
2
-C
8
-alkanediols or -polyols or C
2
-C
8
-alkylamines as chain extenders; the urethane acrylates can also include polyesterols or polyetherols as structural components; preferred polyisocyanates are
dicyclohexylmethane 4,4′-diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate, trimethylhexamethylene diisocyanate, adducts of such isocyanates with polyhydric alcohols such as trimethylolpropane, dimers or trimers of the isocyanates, such as biurets or isocyanurates.
Preference is given to aliphatic polyisocyanates, the term aliphatic being intended to include nonaromatic alicyclic compounds as well.
Preferred urethane (meth)acrylates are aliphatic urethane acrylates, which contain aromatic ring systems if at all, in minor amounts of, for example, less than % by weight, based on the urethane acrylates, and which with particular preference contain no aromatic ring systems.
Epoxide (meth)acrylates are obtainable by reacting epoxides with (meth)acrylic acid. Examples of suitable epoxides are epoxidized olefins or glycidyl ethers, examples being bisphenol A diglycidyl ether, or aliphatic glycidyl ethers, such as butanediol diglycidyl ether.
Melamine (meth)acrylates are obtainable by reacting melamine with (meth)acrylic acid.
The epoxy (meth)acrylates and melamine (meth)acrylates preferably have a number-average molecular weight M
n
of from 500 to 20,000, with particular preference from 750 to 10,000, and, with very particular preference, from 750 to 3000 g/mol; the content of meth(acrylic) groups is preferably from 1 to 5, with particular preference from 2 to 4, mol per 1000 g of epoxy (meth)acrylate or melamine (meth)acrylate (gel permeation chromatography, PS standard, THF solvent).
Preferred radiation-curable compositions comprise from to 80% by weight, with particular preference from to 50% by weight, of carbonate (meth)acrylates a) and from 20 to 95% by weight, with particular preference from 50 to 90% by weight, of urethane (meth)acrylates, epoxy (meth)acrylates or melamine (meth)acrylates b).
In addition to the above (meth)acrylic compounds the radiation-curable composition may include other ethylenically unsaturated, free-radically polymerizable compounds.
Mention may be made in particular of compounds c), which have at least one (meth)acrylic group but are different from the above (meth)acrylic compounds a) and b).
Suitable compounds c) are poly(meth)acrylates of aliphatic polyols, especially di- to pentahydric alcohols, which other than the hydroxyl groups contain no further functional groups or, at best, ether groups.
Examples of such alcohols are bifunctional alcohols, such as ethylene glycol, and propylene glycol, and the representatives with higher degrees of condensation, such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, etc., butanediol, pentanediol, hexanediol, neopentyl glycol, cyclohexanedimethanol, trifunctional alcohols and alcohols of higher functionality, such as glycerol, trimethylolpropane, butanetriol, trimethylolethane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, sorbitol, mannitol and the corresponding alkoxylated alcohols, especially ethoxylated and propoxylated alcohols.
Suitable poly(meth)acrylates in particular have a molecular weight of less than 1000 g/mol, with particular preference of less than 600 g/mol, and have from 2 to 4 (meth)acrylic groups in the molecule;
BASF - Aktiengesellschaft
Tarazano D. Lawrence
Thibodeau Paul
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