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
2001-06-28
2004-04-27
Cheung, William (Department: 1713)
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...
C524S425000, C524S431000, C524S487000, C524S500000, C524S503000
Reexamination Certificate
active
06727305
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a filler-containing polymer dispersion which contains organic or inorganic filler particles and particles of at least one synthetic organic polymer, the ratio of the particle size of the filler particles to the particle size of the polymer particles being in the range from 1.1:1 to 20:1.
BACKGROUND OF THE INVENTION
Polymer particles with a diameter of about 0.01 to about 30 &mgr;m play an important role in many areas of plastics technology. Adhesives or coating compositions containing polymer particles with diameters in this range are frequently used in particular for bonding articles or for coating surfaces. Examples of the range of applications include decorative surface coating in the form of paint coatings or other coatings and the bonding of two surfaces having identical or different properties with adhesives of the type frequently encountered in the field of bonding.
The polymer particles mentioned are generally produced by polymerization of olefinically unsaturated monomers of which the properties can be modified by the polymerization of mixtures of various monomers, for example by co- or terpolymerization. The modified properties of a single polymer particle are generally transferred as a collective property to a surface coating or bond prepared with the aid of such polymer particles. Collective properties which are often subjected to an application-related modification include, for example, hardness, elasticity and—above all in adhesive applications—bond strength, open time or early adhesion.
Certain properties of the composition used to prepare the coating or the bond, for example the surface coating composition or the adhesive, are just as important. In this connection, viscosity, flow behavior or residual monomer content are often modified in dependence upon the desired application.
Inorganic or organic fillers are often added to a surface coating composition or an adhesive containing polymer particles to modify the above-mentioned properties of a surface coating or a bond. Inorganic fillers reduce the level of organic polymer material in the coating and thus contribute to greater hardness of the coating and to protection of the environment and raw materials through a lower content of organic polymers. Organic fillers are capable of imparting certain combined properties of the filler and polymer particles present therein, for example to a polymer dispersion.
Whereas mixtures of polymer particles and fillers frequently lead to dull, rough surfaces in the field of surface coating, their effect in adhesives is often that the strength and elasticity of adhesive bonds are greatly reduced. In addition, the presence of fillers in polymer dispersions often contributes to a reduction in early adhesive strength.
Such effects are drastically noticeable above all in the field of high-quality applications of surface coatings and bonds, such as high-gloss paints and bonds in the paper or furniture industry. For example, a significant reduction in ultimate adhesive strength on wood is often observed, accompanied by reduced early adhesion.
EP-A 0 392 065 relates to polymer-coated filler particles where a filler core is coated with a membrane of a hydrophobic polymer. To produce these polymer-coated particles, a monomer is polymerized in aqueous dispersion in the presence of filler particles and an amphiphilic polymer. The document in question does not contain any teaching on the production of filler-containing polymer dispersions in which the filler particles and the polymer particles are present substantially alongside one another.
DE-OS 22 43 687 relates to an adhesive, more particularly for the production of corrugated cardboard. Although this document does describe a polymer dispersion in which polymer particles and mineral particles are present together and does indicate size ranges for the particular particles, it does not contain any teaching as to the particle size ratio along the lines of the present specification.
Accordingly, the problem addressed by the present invention was to overcome the above-mentioned disadvantages of the mixtures of polymer particles and fillers known from the prior art. More particularly, the problem addressed by the present invention was to provide a filler-containing polymer dispersion which would have the advantages of the mixtures of polymer particles and fillers known from the prior art without any of their known disadvantages.
Accordingly, a particular problem addressed by the present invention was to provide a filler-containing polymer dispersion which could be used for the production of high-quality surface coatings or bonds.
Another problem addressed by the invention was to provide a filler-containing polymer dispersion which could be used as a high-strength adhesive, particularly on wood.
A further problem addressed by the invention was to provide a filler-containing polymer dispersion with a low residual monomer content.
Yet another problem addressed by the invention was to provide an adhesive which would have an adequate open time, high early adhesion and a low viscosity coupled with excellent flow behavior.
A final problem addressed by the invention was to provide a process for the production of such filler-containing polymer dispersions.
BRIEF DESCRIPTION OF THE INVENTION
The problems stated above are solved by a filler-containing polymer dispersion which contains organic or inorganic filler particles and particles of at least one synthetic organic polymer polymerized in the presence of the filler particles, the ratio of the particle diameter of the filler particles to the particle diameter of the polymer particles being in the range from 1.1:1 to 20:1.
Accordingly, the present invention relates to a filler-containing polymer dispersion which contains water, particles of at least one organic or at least one inorganic filler or a mixture thereof (filler particles) and particles of at least one synthetic organic polymer polymerized in the presence of filler particles of at least one type (polymer particles), characterized in that the ratio of the particle size of the filler particles to the particle size of the polymer particles is in the range from 1.1:1 to 20:1.
It has been found that surface coating compositions and surface coatings, adhesives and adhesive bonds at least comparable with filler-free coatings, but superior to the filler-containing systems known from the prior art in regard to open time, bond strength and early adhesion can be obtained using the polymer dispersions according to the invention. In addition, the filler-containing polymer dispersions according to the invention generally have a lower viscosity and better flow behavior than the system known from the prior art with comparable polymer contents and filler contents.
A process according to the invention for the production of the filler-containing polymer dispersions is also distinguished from the poly-merization processes known from the prior art by the fact that it shortens the polymerization time in relation to comparable systems, provides for easier temperature control and leads to polymer dispersions with a reduced content of residual monomers in relation to polymer dispersions produced by polymerization processes known from the prior art.
Accordingly, the present invention relates to a filler-containing polymer dispersion which contains water, particles of an organic or inorganic filler (filler particles) or of a mixture of two or more organic or inorganic fillers or a mixture of two or more thereof and particles of at least one synthetic organic polymer polymerized in the presence of the filler or the fillers (polymer particles), the ratio of the particle size of the filler particles to the particle size of the polymer particles being in the range from 1.1:1 to 20:1.
Accordingly, the polymer dispersion according to the invention contains either inorganic filler particles of one type or organic filler particles of one type or inorganic filler particles of two or more different types or organic filler partic
Harper Stephen D.
Henkel Kommanditgesellschaft auf Aktien
Murphy Glenn E. J.
Ortiz Daniel S.
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