Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
1998-03-06
2002-08-13
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S074500
Reexamination Certificate
active
06433125
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the use of oleochemical polyols as reactive diluents in coating compositions. The use of such dilution systems results in a saving of up to 60% of solvent in high-solids polyurethane systems.
BACKGROUND OF THE INVENTION
Polyurethanes may be used in various forms including, for example, elastomers, foams, casting resins, composite materials, paints and other coatings. Polyurethane-based products such as these are normally produced by reacting aliphatic, aromatic and even heterocyclic isocyanates with high molecular weight polymers containing hydroxy groups. The properties of the resulting polyurethanes are largely determined by the nature and mixing ratio of the basic monomers and by any additives present. One of the most important applications of polyurethanes is in the field of coating compositions. Polyurethane films exhibit, for example, good substrate adhesion, gloss, electrically insulating properties, low gas permeability, resistance to water and solvents and high resistance to weathering. In addition, they can be produced with different degrees of flexibility and under various temperature conditions.
In general, any polyhydroxy compound may be used together with a component containing at least two isocyanate groups for the production of polyurethanes. Hydroxyl-terminated polyesters with or without additional hydroxy groups on the polymer chain, hydroxyl-terminated polyethers, copolymers of hydroxyl-functionalized acrylates and/or methacrylates with acrylate and/or methacrylate esters, styrene, copolymers of allyl alcohol and other unsaturated monomers and also alkyd resins are preferably used as the polymeric polyols. Unfortunately, hydroxy-functional polymers such as these are highly viscous resins and require solvents, in some cases considerable quantities of solvents, to obtain a viscosity suitable for application through spray nozzles.
One way of reducing the viscosity of coating compositions containing high molecular weight resins is to mix the polymeric polyols with low molecular weight, hydroxyl-terminated low-viscosity polyethers. However, the disadvantage of this is that the polyurethanes formed exhibit low hydrolysis stability, high sensitivity to solvents and poor weathering behavior. Another way of reducing the viscosity of a coating composition is to use low molecular weight isocyanates as reactants for the polymeric polyols. Unfortunately, the volatility and toxicity of these compounds can lead to serious environmental problems and to health problems for people involved in their processing. The stringent safety precautions involved make this method of reducing viscosity uneconomical.
Accordingly, most commercially obtainable isocyanates are reaction products of low molecular weight polyols with polyisocyanate compounds in which the volatility of the isocyanate component is reduced by the high molecular weight of the reaction products with the polyols. A disadvantage of the relatively high molecular weight isocyanates described herein is that, in admixture with the polymeric polyols, their viscosity is only slightly reduced so that they are not easy to apply, for example through spray nozzles. As a result, solvent again has to be added in a considerable quantity to reduce the viscosity of the coating composition to a level suitable for application.
One method of using reactive solvents is to mix low molecular weight diols, for example ethylene glycol, propylene glycol, glycerol and trimethylol propane (TMP) or liquid oligomers thereof, with the coating composition. Unfortunately, the use of low molecular weight reactive solvents as chain extenders for the isocyanate component often leads to fragile, hydrolysis-sensitive polyurethane films which are generally unable to satisfy the performance requirements for modern materials. Problems can also be caused by the incompatibility of most polyisocyanate components with the low molecular weight polyols which often leads to phase separation and hence to inadequacies in the material produced.
To reduce the amount of solvent in polyurethane-based coating compositions, it is possible for example to use low-viscosity hydrophobic polyols which, on curing of the coating composition, become part of the coating and thus reduce solvent emission.
CA 850,672 describes the use of oleochemical polyols for reducing viscosity in polyurethane-based coating compositions. In this case, the partial incompatibility of the oleochemical polyols with the OH-functionalized polymers is overcome by heating the components at 250° C. The possibility of mixing the coating composition with inert solvents to reduce solvent consumption and to improve the compatibility of the reactants is not mentioned.
U.S. Pat. No. 4,535,142 describes the use of ester-linked diricinoleate derivatives as reactive diluents in high-solids coatings. One of the disadvantages involved in such an application is, for example, the dependence on a single raw material. Another disadvantage is that, because ricinoleic acid is used, the number of OH groups can only be varied at considerable cost, if at all.
The problem addressed by the present invention was to provide a reactive diluent which would enable the consumption of conventional solvents inert to isocyanate groups to be reduced, in general distinctly reduced. Another problem addressed by the invention was to enable the reactive diluent to be used together with other solvents in such a way that the components would be compatible with no need for an additional thermal homogenization step and all the required components would be homogeneously miscible. Another problem addressed by the invention was to provide a polyurethane-based coating composition and a process for its production.
It has now surprisingly been found that up to 60% by weight of solvent can be saved by using ring opening products of carboxylic acid ester epoxides with dihydric or higher alcohols as reactive diluents in such coating compositions.
DESCRIPTION OF THE INVENTION
The present invention relates to the use of ring opening products of carboxylic acid ester epoxides with dihydric or higher alcohols in admixture with polymeric polyols, isocyanates, inert solvents and, optionally, typical additives as reactive diluents for the production of coating compositions.
Starting materials for the reactive diluents according to the invention are carboxylic acid esters, carboxylic acid esters of aliphatic or cycloaliphatic carboxylic acids containing 6 to 44 carbon atoms being preferred. Since the carboxylic acid esters are intended to be subjected to epoxidation in a following step, one or more C—C double bonds are advantageously already present in the carboxylic acid. However, it is also possible in accordance with the invention to use carboxylic acids of which the C—C double bond first has to be produced synthetically by a chemical transformation such as, for example, elimination or synthesis of a C—C double bond.
Preferred carboxylic acid ester epoxides are those which can be produced from fatty acids and/or fatty acid esters, more particularly from fatty acids and/or fatty acid esters or derivatives of fatty acids and/or fatty acid esters of natural origin.
These include, for example, the triglycerides beef tallow, palm oil, peanut oil, castor oil, rapeseed oil, cottonseed oil, soybean oil, train oil, sesame oil, sunflower oil, corn oil, poppyseed oil, perilla oil, cereal seed oil and linseed oil and also tall oil fatty acids and esters thereof.
The fatty acid esters may be obtained both by direct esterification of the fatty acid with the desired alcohol and by transesterification of fatty acid esters of monohydric or polyhydric alcohols.
Aliphatic alcohols are generally used for the transesterification, the alcohols normally having a functionality of 1 to 10. Alcohols with a functionality of 1 to 5 are preferably used, alcohols with a functionality of 1 to 2 being particularly preferred for the purposes of the invention. It does not matter whether the alcohol used for the transesterification is linear, b
Gress Wolfgang
Gruetzmacher Roland
Heidbreder Andreas
Hirschberger Birgit
Hoefer Rainer
Drach John E.
Gorr Rachel
Henkel Kommanditgesellschaft auf Aktien
Trzaska Steven J.
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