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...
Reexamination Certificate
2001-06-13
2003-07-08
Niland, Patrick D. (Department: 1714)
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...
C524S591000, C524S839000, C524S840000, C524S507000, C525S123000, C525S127000, C525S128000, C525S455000
Reexamination Certificate
active
06590028
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to aqueous two-component polyurethane systems, a process for their production, and their use for the production of coatings having increased impact strength, high stability properties and outstanding optical properties.
Ecological issues play a significant role in surface technology. One particularly urgent problem is the reduction of the amounts of organic solvents used for lacquers and coating materials.
From EP-A 358 979 it is known that where use is made of selected polyhydroxyl compounds based on vinyl polymer by way of reaction partners for organic polyisocyanates with free isocyanate groups aqueous two-component polyurethane systems can be produced by the polyisocyanates with free isocyanurate groups being emulsified in the aqueous polymer solution or dispersion. The polyhydroxyl compounds described in EP-A 0 358 979 are preferably radically polymerised in organic solution and then transferred immediately into the aqueous solution of a neutralising agent—usually ammonia or tertiary amines—and dissolved in water. In this case the organic solvent may remain in the aqueous medium or be removed by distillation, as required.
The polymer polyols produced in this manner normally have monophase morphology—that is to say, they exhibit either thermoplastic or elastomeric properties also after crosslinking and formation of films with suitable hydrophobic and/or hydrophilised polyisocyanates. With a view to the production of polyurethane films having the properties of a thermoplastic elastomer that possesses both excellent toughness properties and a high level of strength, a monophase structure of such a polymer polyol is generally insufficient.
It has been shown that only polymer-polyol systems of biphase or multiphase structure in combination with suitable polyisocyanates result in polyurethane coatings with a high level of toughness, particularly at low temperatures.
SUMMARY OF THE INVENTION
The invention therefore provides two-component polyurethane coating agents that contain by way of binding-agent component a) a graft polymer consisting of at least two polyol components, the first being linked covalently or adsorptively as an elastic component a1) with a second thermoplastic component a2), and a polyisocyanate component b) with a viscosity of at the most 10,000 mPa·s, consisting of at least one organic polyisocyanate in quantities corresponding to an NCO/OH equivalent ratio from 0.2:1 to 5:1, characterised in that component a) is represented by an aqueous solution and/or dispersion of the aforementioned graft polymer, in which the polyisocyanate component b) is present in emulsified or solubilised form.
DETAILED DESCRIPTION OF THE INVENTION
Component a) comprises a polyol component that consists of at least two covalently or adsorptively linked polyol phases a1) as elastomer constituent and a2) as thermoplastic constituent based on vinyl polymer.
In this connection the elastomer constituent a1) may serve as graft base, onto which the thermoplastic constituent a2) has been radically grafted, and the thermoplastic constituent a2) may equally serve as graft base, onto which the elastomer constituent a1) has been grafted.
Polyol constituent a1) comprises an elastomer component that contains hydroxyl groups, sulfonate and/or carboxylate groups, preferably carboxylate groups, and optionally sulfonic-acid and/or carboxyl groups, preferably carboxyl groups. Component a1) comprises polymers of olefinically unsaturated monomers which preferably have a hydroxyl-number from 8 to 264, preferably 16 to 198 mg KOH/g solid resin, an acid-number (relative to the sum of the non-neutralised and neutralised acid groups) from 0 to 100, preferably 3 to 50 mg KOH/g solid resin. The elastomer component a1) has a glass temperature (measured by the DSC or DMA method) of at most 0° C., preferably at most −10° C.
The thermoplastic constituent a2) is likewise a polyol component that contains hydroxyl groups, sulfonate and/or carboxylate groups, preferably carboxylate groups, and optionally sulfonic-acid and/or carboxyl groups, preferably carboxyl groups. Component a2) is likewise a polymer of olefinically unsaturated monomers that have a hydroxyl-number from 16 to 264, preferably 33 to 198 mg KOH/g solid resin, an acid-number (relative to the sum of the non-neutralised and neutralised acid groups) from 3 to 100, preferably 5 to 50 mg KOH/g solid resin. The thermoplastic component a2) has a glass temperature of at least 0° C., preferably at least +10° C.
Quite particularly preferred are elastomer components a1) that are constructed from the following comonomer components:
a1 a) 0.4-7.7 wt.-% acrylic acid and/or methacrylic acid;
a1 b) 3.4-50.8 wt.-% acrylic 2-hydroxyethylester and/or acrylic hydroxy-propyl-ester and/or methacrylic 2-hydroxyethylester and/or methacrylic hydroxypropylester;
a1 c) 0-20 wt.-% methacrylic methylester and/or acrylonitrile and/or methacrylonitrile and/or styrene or substituted styrenes as comonomers with a character imparting strength and hardness;
a1 d) 70-96 wt.-% methacrylic alkylester with 2 to 12 C atoms in the alkyl residue and/or acrylic alkylester with 1 to 12 C atoms in the alkyl residue as elasticising components;
a1 e) 0-5 wt.-% crosslinking comonomers such as, for example, divinyl-benzene, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, allyl(meth)acrylate,
where the wt.-% of a1 a) to a1 e) sum to 100 and where the glass temperature lies below −10° C.
Quite particularly preferred are thermoplastic components a) that are constructed from the following comonomer components:
a2 a) 0.6-7.7 wt.-% acrylic acid and/or methacrylic acid;
a2 b) 6.8-50.8 wt.-% acrylic 2-hydroxyethylester and/or acrylic hydroxypropyl-ester and/or methacrylic 2-hydroxyethylester and/or methacrylic hydroxypropylester;
a2 c) 30-80 wt.-% methacrylic methylester and/or acrylonitrile and/or methacrylonitrile and/or styrene or substituted styrenes as comonomers with a character imparting strength and hardness;
a2 d) 5-40 wt.-% methacrylic alkylester with 2 to 12 C atoms in the alkyl residue and/or acrylic alkylester with 1 to 12 C atoms in the alkyl residue as elasticising components;
a2 e) 0-5 wt.-% crosslinking comonomers such as, for example, divinyl-benzene, ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, allyl(meth)acrylate,
where the wt.-% of a2 a) to a2 e) sum to 100 and where the glass temperature lies above +10° C.
Elastomer component a1) and thermoplastic component a2) are preferably grafted in weight ratios from 10:90 to 60:40 (with respect to solid resin).
The invention also provides a process for the production of a two-component polyurethane coating agent that contains by way of binding-agent component a) a graft polymer consisting of at least two polyol components, the first being linked covalently or adsorptively as an elastic component a1) with a second thermoplastic component a2), and a polyisocyanate component b) with a viscosity of at the most 10,000 mPa·s, consisting of at least one organic polyisocyanate in quantities corresponding to an NCO/OH equivalent ratio from 0.2:1 to 5:1, characterised in that component a) is represented by an aqueous solution and/or dispersion of the aforementioned graft polymer, in which the polyisocyanate component b) is present in emulsified or solubilised form.
Production of the polymer component a) comprising hydroxyl groups is effected by processes, known as such, of radical polymerisation in organic phase or in aqueous phase. Production of the polymers is preferably effected in the one-pot process by the method of radical emulsion polymerisation in the aqueous medium.
Firstly, either the elastomer component a1) or the thermoplastic component a2) is produced by way of graft base, and subsequently the thermoplastic component a2) or the elastomer component a1), respectively, is grafted on radically.
Possible are continuous or discontinuous polymerisation processes. Of th
Biskup Ulrich
Irle Christoph
Kobusch Claus
Probst Joachim
Niland Patrick D.
Roy Thomas W.
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