Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-05-06
2001-12-11
Woodward, Ana (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C525S131000
Reexamination Certificate
active
06329440
ABSTRACT:
The present invention relates to a process for preparing polyisocyanate polyaddition products by reacting isocyanates with compounds which are reactive toward isocyanates, in the presence or absence of blowing agents, catalysts, auxiliaries and/or additives, and also to polyisocyanate polyaddition products which can be prepared by this process. The invention further relates to the use of thermoplastic particles which have a size of <200 &mgr;m and a melting point in the range from 50 to 300° C. for producing usually foamed polyisocyanate polyaddition products which have greatly reduced the dust formation during sawing.
Furthermore, the invention relates to a process for preparing a low-wear polyisocyanate polyaddition product, in particular a foamed or compact elastomer of this type, by reacting isocyanate components with components comprising compounds which are reactive toward isocyanates in the presence or absence of blowing agents, catalysts, auxiliaries and/or additives and to polyisocyanate polyaddition products which can be prepared by this process. The invention also relates to low-wear compositions, storage-stable components, a process for setting particular properties in polyisocyanate polyaddition products or compositions and to the use of polyisocyanate polyaddition products or compositions for improving the wear behavior and to articles which comprise at least one of the abovementioned materials.
The preparation of polyisocyanate polyaddition products, usually polyurethane and possibly polyisocyanurate products, for example polyurethane foams and compact or foamed elastomers, by reacting an isocyanate component B with a component A comprising compounds which are reactive toward isocyanates, in the presence or absence of blowing agents, catalysts, auxiliaries and/or additives, has been described many times.
In further processing of, for example, polyurethane foams, in particular rigid polyurethane foams which may contain polyisocyanurate structures, sawing the moldings or cutting them by means of a hot wire results in undesirable dust formation and a rough surface.
It is an object of the present invention to develop a process for preparing polyisocyanate polyaddition products by reacting isocyanates with compounds which are reactive toward isocyanates, in the presence or absence of blowing agents, catalysts, auxiliaries and/or additives, which makes it possible to obtain polyisocyanate polyaddition products which have greatly reduced dust formation during further processing involving local action of heat, for example sawing with generation of frictional heat or, in particular, cutting by means of a hot wire, and subsequently have a pleasantly smooth surface.
We have found that this object is achieved by carrying out the reaction of isocyanates with isocyanate-reactive compounds, in the presence or absence of blowing agents, catalysts, auxiliaries and/or additives, in the presence of particles (i) which have a size of <200 &mgr;m preferably <100 &mgr;m, particularly preferably from 2 to 100 &mgr;m, in particular from 10 to 100 &mgr;m, and have a melting point in a range from 50 to 300° C., preferably from 70 to 200° C., or in the presence of particles (ii), which are thermoset, or in the presence of particles (i) and (ii). The particle size of particles (ii) is in the same range as the particle size of particles (i). As particles (i), use is made of generally known compounds or mixtures which have the melting point specified according to the invention and can be brought to the size specified according to the present invention by customary methods, for example by known milling methods or spray drying, or are commercially available in this size. Examples of particles (i) which can be used are polyolefins, polyolefin copolymers and/or waxes, for example polyethylene, polypropylene, polyolefins comprising polyethylene and polypropylene units, which have been copolymerized with maleic acid and/or vinyl acetate, for example EVA, polystyrenes, modified polystyrenes and/or modified polyolefins, Fischer-Tropsch waxes (synthetic paraffin), montan waxes, carnauba wax, candilla wax, vegetable and/or animal waxes, e.g. esters of fatty acids having from 20 to 53 carbon atoms which are esterified with organic alcohols having from 1 to 5 hydroxyl groups, for example glycerol.
Preference is given to using polyolefins which may be modified or unmodified and/or waxes.
Appropriate waxes are commercially available, for example micronized polyethylene wax (AF-31 wax) from BASF Aktiengesellschaft.
For the purposes of the present invention, the size of the particles (i) is the diameter which the particles (i) would have if they were present as spheres having the corresponding volume.
A further problem which frequently gives rise to complaints in the case of articles, particularly foams, films, fibers, moldings and coatings, in particular shoe soles, which comprise at least some polyisocyanate polyaddition products, in particular polyurethanes, is excessively high wear.
This wear has previously been reduced in the case of shoe soles by adding silicone rubber to the polyisocyanate polyaddition products or polyurethanes.
However, the use of silicone rubber has drawbacks, since it can be mixed only in very small amounts and with great technical difficulty with compounds (component A) which are reactive toward isocyanates. This poor miscibility leads, for example, to the silicone rubber and the component A very quickly undergoing phase separation. This leads, for example, to the problem that the mixture of component A and silicone rubber cannot be stored for a prolonged period or cannot be transported over long distances. In general, the occurrence of phase separation makes it necessary for the component A comprising silicone rubber to be stirred again immediately before preparation of the polyisocyanate polyaddition adduct to achieve sufficient mixing of the silicone rubber with the component A.
Furthermore, the addition of silicone rubbers leads only to an apparent improvement in the wear behavior. The materials modified with a silicone rubber produce a wax-like layer on the surface of the article rubbing along the surface of the silicone-modified material. This layer allows better sliding. Thus, for example, the surface of emery paper becomes covered with wax when the material modified with a silicone rubber is rubbed across the emery paper. The wax-layer formed on the emery paper robs the surface of the emery paper of its roughness and thus allows the surface of the emery paper and the surface of the material modified with silicone rubber to slide over one another more readily. In addition, the silicone rubbers are comparatively expensive materials.
A further object of the present invention is to overcome the abovementioned disadvantages associated with the silicone rubber and, in particular, to provide a low-wear polyisocyanate polyaddition product or a low-wear composition and a storage-stable component, particularly one which has less tendency toward phase separation.
Furthermore, it is preferred according to the present invention for the polyaddition product to have a wear of less than 250 mg in accordance with DIN 53516. For this purpose, the polyaddition product preferably contains thermoset particles (ii), either alone or in combination with particles (i). These polyaddition products will hereinafter be referred to as “low-wear” polyisocyanate polyaddition products.
For the purposes of the present invention, thermoset means that materials having these properties are not fusible. Thermoset particles can, according to the present invention, be either polymers or inorganic materials. In the case of polymers, it is preferred that they be crosslinked. Particularly preferred polymers are polycondensates, for example bakelites, polyamides, polyimides and the like. Inorganic thermosets are preferably mineral materials. Among these, particular preference is given to the fillers described further below in the present application.
The thermoset particles (ii) preferably have the same
Kappes Anton
Kreyenschmidt Martin
Pittrich Klaus
Scherzer Dietrich
Treuling Ulrich
BASF - Aktiengesellschaft
Borrego Fernando A.
Cameron Mary K.
Woodward Ana
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