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
2001-10-04
2003-12-02
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...
C528S056000, C528S057000, C528S058000, C528S080000, C528S081000, C528S083000, C528S275000, C528S276000, C528S277000, C528S278000, C528S279000, C528S280000, C528S281000, C528S282000, C528S283000, C528S284000, C528S285000, C528S286000, C528S287000, C528S293000, C528S355000, C528S356000, C528S357000, C528S358000, C502S011000, C526S090000, C526S123100
Reexamination Certificate
active
06657036
ABSTRACT:
The present invention relates to the use of heterogeneous catalysts in the preparation of polycondensation resins and polyaddition resins. The present invention further relates to polycondensation resins and polyaddition resins which are preparable by heterogeneous catalysis. The invention further relates to novel processes for preparing polycondensation resins and polyaddition resins. The present invention relates not least to the use of the polycondensation resins to prepare polyaddition resins.
As is known, polycondensation is a step reaction of low molecular mass compounds to give oligomers and/or polymers. The reaction rate of the polycondensation may be increased by raising the reaction temperature. However, there are limits on an arbitrary raising of the reaction temperature within fairly short intervals of time, since fairly large reactors in particular cannot be supplied with sufficient thermal energy in order to melt the reaction mixture more quickly and to condense it. Further limiting parameters are the utilizable thermal energy available, the heat transfer coefficients, the foaming induced by the distillative removal of, for example, water, or the viscosity of the polycondensate, which increases during the step reaction and makes rapid escape of, for example, water more and more difficult. Moreover, high reaction temperatures are often deleterious for the intrinsic color of the polycondensate.
It is known to increase the reaction rate of polycondensation by means of catalysts such as lithium octoate, dibutyltin oxide, dibutyltin dilaurate, stannic acid or para-toluenesulfonic acid and so to shorten the synthesis time. However, these catalysts are often unwanted in the subsequent products of the polycondensation resins. Where, for instance, the polycondensation resins are used for the preparation of polyaddition resins, these catalysts may induce unwanted secondary reactions which detract from the usefulness of the polyaddition resins. A typical example is the preparation of polyurethane prepolymers containing isocyanate groups from polyesters containing terminal hydroxyl groups (polyesterpolyols). The catalysts commonly employed also catalyze reactions of the isocyanate groups, so that numerous byproducts are produced in relatively large amounts, impairing the profile of performance properties of the polyaddition resins. Where the polycondensation resins are used directly to prepare coating materials, the catalysts may accelerate the reaction with the crosslinking agents to such a large extent that prematurely cross-linked products are formed. In the finished coating, such products manifest themselves as specks. It is therefore necessary to remove the aforementioned catalysts from the polycondensation resins, although this is not easy to do.
It is an object of the present invention to provide novel processes for the polycondensation and polyaddition of low molecular mass compounds, said processes no longer having the disadvantages of the prior art but instead permitting the reaction rate to be increased without problems using catalysts without thermal damage to the polyaddition resins or polycondensation resins formed. Moreover, the catalysts employed in the novel processes ought no longer to induce any unwanted secondary reactions in the subsequent products of the polycondensation resins and the polyaddition resins. In addition, the catalysts should be easy to remove, if required, after the step reactions.
The invention accordingly provides the novel process for preparing polycondensation resins by polycondensing low molecular mass compounds with elimination of small molecules in a reactor, characterized in that heterogeneous catalysts are used.
The invention additionally provides the novel process for preparing polyaddition resins by polyaddition in a reactor, which is likewise characterized in that heterogeneous catalysts are used.
In the text below, the novel processes for preparing polycondensation resins and polycondensation resins are referred to comprehensively for the sake of brevity as “processes of the invention”.
The invention additionally provides the novel polycondensation resins and polyaddition resins which are preparable in the presence of heterogeneous catalysts.
The invention further provides novel polyaddition resins which are preparable using the polycondensation resins of the invention.
In the text below, the novel polycondensation resins are referred to as “polycondensation resins of the invention” and the novel polyaddition resins are referred to as “polyaddition resins of the invention”.
In the light of the prior art it was surprising and unforeseeable for the person skilled in the art that the object on which the present invention is based could be achieved by the inventive use of heterogeneous catalysts. Still more surprising in this context was that a large number of organic and inorganic substances may be used as heterogeneous catalysts. The broad diversity of catalysts available in accordance with the invention makes it possible in an extremely advantageous and simple way to select the best catalyst for the polyaddition and polycondensation in hand. Moreover, the extremely broad diversity of forms in which the heterogeneous catalyst may be provided allows it to be adapted advantageously and simply to existing reactor geometries and to be separated simply from the reaction products. Even less foreseeable was that the advantages of the processes of the invention and of the polycondensation resins or polyaddition resins of the invention would extend fully to their subsequent products. For instance, coating materials based on the resins of the invention have a particularly advantageous profile of performance properties. The same applies to the polyaddition resins of the invention prepared using the polycondensation resins of the invention.
The first process of the invention is employed in the preparation of polycondensation resins. This is a step reaction which proceeds with the elimination of small molecules such as water, alcohols, phenols or hydrogen halides.
Examples of polycondensation resins which may be prepared by the process of the invention are polyamides, polyimides, polyesters, polycarbonates, amino resins, phenolic resins, polysulfides or urea resins, especially polyesters.
The second process of the invention is employed in the preparation of polyaddition resins. The polyaddition resins are formed in step reactions via reactive oligomers as discrete intermediates. The addition reactions take place without elimination of small molecules, frequently with displacement of hydrogen atoms. The reactive oligomers are also referred to as prepolymers. They contain functional groups that are still reactive, and in polymer synthesis participate in the final structure of the polymers.
Examples of polyaddition resins of the invention which may be prepared by the process of the invention are polyurethanes or polyureas, especially polyurethanes, such as are used in particular for the preparation of coating materials.
Examples of prepolymers which may be prepared by the process of the invention are the polyurethane prepolymers which still contain free isocyanate groups.
The essential process measure of the processes of the invention is the use of at least one heterogeneous catalyst which is substantially or completely insoluble in the reaction mixture. In the context of the present invention, the term “substantially insoluble” indicates that the reaction mixture contains only a number of dissolved fractions of the heterogeneous catalyst that is such that they do not influence the profile of properties of the polycondensation resin of the invention and of the polyaddition resin of the invention.
Heterogeneous catalysts suitable for use in accordance with the invention include, in particular, coated and uncoated, insoluble or sparingly soluble metal oxides and nonmetal oxides, salts, sulfides, selenides, tellurides, zeolites, phosphates, heteropolyacids and/or acidic or alkaline ion exchange resins.
The heterogeneous catalysts for use in acco
Fuchs Eberhard
Jung Werner-Alfons
Rink Heinz-Peter
Straehle Wolfgang
BASF Coatings AG
Gorr Rachel
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