Polymer concentrates with improved processability

Abstract

New polymer concentrates on the basis of polymer additives, like e.g. fillers and flame-retardants, are provided which have in particular an increased bulk density compared to the polymer additives as such. This increased bulk density leads to a substantial improvement in the processability of such concentrates, their dispersibility during compounding and the properties of the resulting polymer compound. Processing improvements include less dust, faster processing and more homogeneous additive dispersion. The invention also provides a process for preparing such new polymer concentrates, a process for preparing polymer compounds containing the new polymer concentrates, the respective polymer compounds and a process for preparing formed parts thereof. Such formed parts have more uniform properties such as density, wall thickness, and in case of the flame-retardants more homogeneous and consistent flame retardancy.

1 . A concentrate containing
 (1) one or more polymer additives and   (2) one or more polymers which comprise repeating units of ethylene, vinyl acetate and optionally one or more other monomers,   wherein
 (a) the concentrate contains less than 10% by weight of one or more polymers (2), based on the total weight of the polymer additive(s) (1) and the polymer(s) (2), 
 (b) the concentrate is obtainable by mixing the polymer additive(s) (1) with a solution of the polymer(s) (2) in a solvent and removing the solvent, 
 (c) the mean primary particle size (“d 50 ”) of the polymer additive(s) (1) prior to the mixing with the solution of the polymer(s) (2) is less than 10 μm, and 
 (d) the concentrate has a bulk density which is at least 50% greater than that of the polymer additive(s) (1) prior to the mixing with the solution of the polymer(s) (2), wherein such bulk density is measured in accordance with DIN ISO 697 from January 1984. 
   
     
     
         2 . The concentrate according to  claim 1 , wherein the mean primary particle size (“d 50 ”) of the polymer additive(s) (1) prior to the mixing with the solution of the polymer(s) (2) is less than 5 μm. 
     
     
         3 . The concentrate according to  claim 1 , wherein the mean primary particle size (“d 50 ”) of the polymer additive(s) (1) prior to the mixing with the solution of the polymer(s) (2) is less than 2 μm. 
     
     
         4 . The concentrate according to  claim 1 , wherein the mean primary particle size (“d 50 ”) of the polymer additive(s) (1) prior to the mixing with the solution of the polymer(s) (2) is in the range of from 0.5-1.5 μm. 
     
     
         5 . The concentrate according to  claim 1 , wherein the polymer additives (1) are fillers, flame-retardants, flame-retardant synergists, pigments, other finely powdered polymer additives or any mixtures thereof. 
     
     
         6 . The concentrate according to  claim 5 , wherein a mixture of a filler and a flame-retardant or a mixture of a filler, a flame-retardant, and a flame-retardant synergist is used. 
     
     
         7 . The concentrate according to  claim 5  or  6 , wherein as flame-retardants aluminium trihydroxide (ATH), magnesium hydroxide, antimony trioxide, or mixtures thereof are used. 
     
     
         8 . The concentrate according to  claim 5  or  6 , wherein as flame-retardant synergists zinc borate, antimony trioxide, sodium antimonate, or mixtures thereof are used. 
     
     
         9 . The concentrate according to  claim 5  or  6 , wherein as fillers carbon black, graphite, metal powders, talc, clays, mica, wollastonite, silica, calcium carbonate, hydrated minerals, boron-containing compounds, zinc-containing compounds, antimony-containing compounds, or mixtures thereof are used. 
     
     
         10 . The concentrate according to  claim 5 , wherein as pigments iron oxides or titanium dioxide are used. 
     
     
         11 . The concentrate according to  claim 1 , wherein the polymer(s) (2) contain 40 to 90% by weight vinyl acetate and 10 to 60% by weight ethylene and optionally 10 to 50% by weight of one or more further monomers, wherein the sum of all monomers in the polymer(s) (2) still has to give 100% by weight. 
     
     
         12 . The concentrate according to  claim 1 , wherein the polymer(s) (2) contain 60 to 80% by weight vinyl acetate and 20 to 40% by weight ethylene and optionally 10 to 50% by weight of one or more further monomers, wherein the sum of all monomers in the polymer(s) (2) still has to give 100% by weight. 
     
     
         13 . The concentrate according to  claim 1 , wherein the concentrate contains 2 to 10% by weight of one or more polymers (2), based on the total weight of the polymer additive(s) (1) and the polymer(s) (2). 
     
     
         14 . The concentrate according to  claim 1 , wherein the concentrate contains 3 to 8% by weight of one or more polymers (2), based on the total weight of the polymer additive(s) (1) and the polymer(s) (2). 
     
     
         15 . The concentrate according to  claim 1 , wherein the concentrate contains 3 to 6% by weight of one or more polymers (2), based on the total weight of the polymer additive(s) (1) and the polymer(s) (2). 
     
     
         16 . A method for preparing polymer compounds comprising mixing a concentrate according to  claim 1  with one or more polymers (3). 
     
     
         17 . The method according to  claim 16 , wherein as polymers (3) nitrile rubber (“NBR”), hydrogenated nitrile rubber (“HNBR”), polyamides, polycarbonate, polyvinylchloride (“PVC”), AEM or EVM are used. 
     
     
         18 . A polymer compound comprising the concentrate according to  claim 1  and one or more polymer(s) (3). 
     
     
         19 . The polymer compound according to  claim 18  comprising as polymers (3) nitrile rubber (“NBR”), hydrogenated nitrile rubber (“HNBR”), polyamides, polycarbonate, polyvinylchloride (“PVC”), AEM or EVM. 
     
     
         20 . A process for preparing formed parts containing a polymer compound comprising processing the concentrate according to  claim 1  with one or more polymer(s) (3). 
     
     
         21 . Formed parts of the polymer compounds according to  claim 19 . 
     
     
         22 . Formed parts according to  claim 21  which are profiles, equipment housings, or functional articles. 
     
     
         23 . Formed parts according to  claim 22  which are sealing profiles or window profiles, equipment housings for computers, household or industrial electrical equipment, hoses or belts.