CA2349030C - Improved processibility and lacing resistance when silanized pigments are incorporated in polymers - Google Patents

Abstract

White-pigmented polymers (particularly, polyolefins such as polyethylene) containing white pigments treated with at least one silane or a mixture of at least one silane and at least one polysiloxane are disclosed to improve processibility in compounding and improve performance properties such as lacing resistance in a polymeric matrix.

Description

V1'O y5123192 PCT/US95102811 . TITLE
IMPROVED PROCESSIBILITY AND LACING RESISTANCE WHEN
SILA1~'1ZED PIGMENTS ARE INCORPORATED 1N POLYMERS
BACKGROL>Nn nF THE 1 NTinl~
The present invention relates to white-pigmented polymers (particularly, polyolefins such as polyethylene) containing white pigments treated with an organosilicon compound to improve processibility in compounding and improve performance properties such as lacing resistance in a polyolefin matrix. ' Treatment of Ti02 pigment with organosilicon compounds to improvt dispersibility in a polymer matrix is well known in the ari. For example, U.S.
Patents 4,061,503 and 4,151,154 disclose enhanced dispersibility of Ti02 in paints and plastic. Therein, the Ti02 is surface treated with a silane possessing at least two hydrolyzable groups bonded to silicon and an organic group containing a polyalkylene oxide group.
In addition, U.S. Patent 4,810,305 discloses.a modified hydrophobic pigment or filler containing 0.05 to 10 weight % of an organopolysiloxane, with improved dispers'bility in synthetic resins.
However, deficiencies in the prior ari include, but are not limited to, (1) unacceptable processibility, i.e., dispcrsibility of Ti02, pigment in a polymeric matrix at slow rates; and (2) lacing , i.e., development of imperfections in a polyolefin matrix. lacing occurs as a result of volatiles released from the pigment during high temperature polyolefin fabrication processes. Lacing may also be attributable to Ti02 concentrates picking up moisture. A further disadvantage is that higher loadings of Ti02 pigment in a polymer concentrate result in slower processing rates.
It has been found that the above combined disadvantages of the prior an can be overcome by the present invention.
In accordance with one aspect of the present invention, there is provided a highly loaded polymer matrix comprising polymer resin and 50 to 87 % by weight silanized TiOz pigment, based on the weight of the polymer matrix, exhibiting enhanced processibility, wherein the Ti02 pigment has a coating of 0.1 to 5% by weight, based silanized Ti02 pigment, of an organosilicon compound selected from at least one silane, or a mixture of at least one silane and at least one polysiloxane. It has been found that the silanized pigmentary Ti02 provides a unique combination of enhanced processibility in a polymeric matrix having higher Ti02 loadings, and improved end use performance properties such as lacing resistance in a polyolefin matrix at Ti02 concentrations ranging from about 0.2 to about 20 % by.weight, based on the weight of the polyolefin matrix.
The Ti02 pigments useful in the present im~ention generally are in the rutile or anatase crystalline form. It is commonly made by either a chloride process or a sulfate process. TiCl4 is oxidized to Ti02 particles in the chloride process. Sulfuric acid and ore containing titanium are dissolved, and the resulting solution goes through a series of steps to yield Ti02, in the sulfate process.
Both the sulfate and chloride processes are described in greater detail in "Ihe Pigment Handbook", Vol. 1, 2nd Ed., John Wiley & Sons, NY (1988), the teachings of which may be referred to herein. The optimum average particle size can range' from about 0.005 to about 1 micron. The Ti02 pigments may also contain ingredients added thereto to further improve dispersibilily characteristics or other properties such as durability. Thus, by way of example, but not limited thereto, the pigment may contain additives and/or inorganic oxides, such as aluminum, silicon or tin as well as triethanolamine, trimethylolpropane, phosphates, etc.
"Silanized" Ti02 is defined herein to refer to Ti02 treated with either at least one silane, or a mixture of at least one silane and at least one polysiloxane (collectively referred to herein as organosilioon compounds).
Suitable silanes have the formula:
RxSi(R')4-x wherein R is a nonhydrolyzable aliphatic, cycloaliphatic or aromatic group having at least 1 to about 20 carbon atoms;
R' is a hydrolyzable group such as an alkoxy, halogen, acetoxy or hydroxy or mixtures thereof; and x=ito3.
For example, silanes useful in carrying out the invention include 3 S octyltriethoxysilane, no~ltriethoxysilane, decyltriethoxysilane, dodecyltriethoxysilane, tridccyltriethoxysilane, tetradecyltriethoxysilane, pentadecyltriethoxysilane, hexaderyltriethoxysilane, heptadecyltriethoxysilane and octadecyltriethoxysilane. .Additional examples of silanes include, R=8-18 carbon atoms; R' = chloro; mcthoxy, hydroxy or mixtures thereof; and x=1 to 3.
Preferred silanes arc R = 8-18 carbon atoms; R' = ethoxy; and x =1 to 3. The R = 8-18 carbon atoms is preferred for enhanced processibility. R' = ethoxy is preferred for ease of handling. Surprisingly, lower chain alkyl silanes resulted in longer processing times.
Mixtures of silanes are contemplated equivalents. Weight content of the silage, based on total silanized pigmentary T i02 is typically about 0.1 to about S
weight %, preferably about 05 to about 1S weight %. In excess of 5 weight % may be used but no particular advantage is observed In an alternative embodiment, a mixture of at least one s0ane with at least one pulysiloxane is useful in carrying out the im~ention. Suitable polysiloxanes have the formula:
(RnSiO~m wherein r R is organic or inorganic groups;
n = 0-3; and m>2.
For example, polydimethylsiloxane (PDMS), vinyl phe~lmethyl terminated dimethyl siloxanes, divinylmethyl terminated polydimethyl siloxane and the like arc suitable polys~7oxanes. PDMS is a preferred polysiloxane. The silane useful in the mixture may be the silane described above with R =1-8 carbon atoms, R' =
aikaacy and x=1 preferred. Weight content of the silent and polysiloxane, based on total silanized pigmentary Ti02, is about 0.1 to about 5.0 weight %, preferably from about 1 to 3 weight %. Especially preferred is about OS to 1 weight % silane with R=4 or 8 carbon atoms, R' =alkoxy, and x =1; and 1 weight % PDMS. The ratio of silent to polysiloxane can be 1 silane:2 polysiloxane up to 2 silane:l polys0oxane.
An especially preferred ratio is 1 silane: 1 polysiloxsne. .
The silane and polysiloxane are commercially ava0able or can be prepared by processes known in the art such as those described in "Organos0icon Compounds", S. Pawlenko, et al., New York (1980), the teachings of which may be referred to herein. Tie method of addition is not especially critical and the Ti02 pigment may be treated with the s0ane in a number of ways. For example, the silane addition can be made neat or prehydrolyzed to a dry pigmentary base, from a slurry, a filtration step, during drying or at a size operation such as a fluid ener~r mill, e.g., micronizer, or media mill as descn'bed in greater detail in copending application entitled "IMPROVED SLURRY PROCESS FOR
PREFAR>IVG SIILAI~IZ.ED Ti02 PIGMENTS, USING A NIF.DIA M1LL", the teachings of which may be referred to herein, or post blending after micronizing. For example, U.S. 3,834,924 descn'bes organosilane and pigment dispersion mixed or blended directly in a suitable solids mixing apparatus. An example of post blending is described in greater detail in U.S. Patents 3,915,735 and 4,141,751. The polysiloxane addition can be made in conjunction with the silane or post addition to the silanized pigment. The sflane addition and polysflaxane addition is descn'bed in greater detsfl below. If water, either a liquid or vapor (steam), is present as a component of the process stream, hydrolysis of the hydrolyzable groups of the silane will occur aad the silane coating wfll bond to the Ti02 base. Prehydrolyzing the silane is a preferred step in treating the Ti02 pigment with the silane. If the silane is added neat to the TiO2 base, then moisture adsorbed on the Ti02 will effect the hydrolysis, but at a lower rate than if excess moisture i's present. Hydrolysis of silanes is descn'bed in greater detail in "Organofunctional Silanes" by Union Carbide (1991), the teachings of which may be referred to herein.
Polymers which are suutable for use in the present im~ention include, by way of example but not limited thereto, polymers of ethylenically unsaturated monomers including olefins such as polyethylene, polypropylene, polybutylene, and copolymers of ethylene with higher olefins such as alpha olefins containing 4 to 10 carbon atoms or vinyl acetate, etc,; vials such as polyvinyl chloride, polyvinyl esters .. such as polyvinyl acetate, polystyrene, acrylic homopolymers and copolymers;
phenolia; alkyds; amino resins; epoxy resins, polyamides, polyurethanes;
phenoxy resins, polysulfones; polycarbonates; polyether and chlorinated polyesters;
polyethers; acetal resins; polyimides; and polyoxyethylenes. The polymers according to the present imrention also include various rubbers and/or elastomers either natural or synthetic polymers based on copolymerization; grafting, or physical blending of various diene monomers with the above-mentioned polymers, all as generally known in the art. Thus generally, the present im~ention is useful for a~
such white-pigmented plastic or elastomeric compositions (collectively referred to herein as a white pigmented polymers) . For example, but not by way of limitation, WO 95123192 ~ PCT/US95I02811 the invention is felt to be particularly useful for polyolefins such as polyethylene, polypropylene, polyvinyl chloride, polyamides and polyesters.
As used herein, '~ligh loaded" Ti02 may vary widely for each polymeric matrix but will be in a well known range for those skilled in the art. For example, in a polyolefin matrix, a high loaded Ti02 would be 50 or above % by weight Ti02 pigment, based on the weight of the polyolefin matrix.
A wide variety of conventional additives may be included in the polymers as is necessary, desirable or conventional for the intended end use.
Such additives include, but are not limited to, antioxidants, light stabilizers, lubricants, thermal processing additives and the like.
Ti02 coated with organosilicon compounds can be incorporated into a melt-fabricable polymer to form the polymer composition of this invention by any melt compounding technique known in the art. Generally, Ti02 and polymer resin are brought together and then mixed in a blending operation that applies shear to the polymer melt. The polymer resin is usually available in the form of powder, granules, pellets, or cubes. Commonly, Ti02 and resin are first combined while the resin is in the solid state (not melted) and dry-blended in some way. This can be done in simple ways, such as by shaking in a bag or tumbling in a closed container, or in more sophisticated ways such as by using blenders having agitators or paddles.
Ti02 and polymer resin can be brought together by co-feeding the materials to internal mixers and allowing a screw to mix them together before the resin reaches the molten state. The melt blending of Ti02 and polymer resin can be done using known equipment, such as single-screw extruders, twin-screw extruders, internal mixers, and the like. Internal mixers are commonly used. The melt blending can be done as part of the process of forming a finished article of the composition, as by melt extrusion. Alternatively, the melt blending can be done in a preliminary step, optionally isolating the polymer composition, e.g., as cubes, followed by forming a finished article in a subsequent process. As one sidlled in the art will recognize, there are many possible variations of the technique for preparing polymer compositions of the invention. One may, for example, first prepare a concentrate having high Ti02 concentration, i.e., one composition of the invention, and then combine the concentrate with polymer resin containing no Ti02 to obtain another composition of the invention.
The highly loaded polymer concentrates are made as described above with the desirable weight % for the intended end use. For example, in polyolefin coneenuates, about 50-87% by weight concentrate may be used to opacity. T'he concentrate is "let down" into the polyolefin. Used herein, "let doom" refers to a ratio or percent of resin mixed with concentrate. Let down may be accomplished in a number of ways and is descn"bed iri great detail in'~ilm F.xtrusipn "
(1992), the teachings of which tray be referred to herein. For exarrxple, in lacing evaluation, a ~~ wt.% to 87 wt.% concentrate msy be let down to about 0.2 to about 20 weight %n by dry mixing polyolefin and extruding at a speafic processing temperature and casting it into a film. Pigment performance is rhea ewatuated in an end use application.
Whe highly loaded silanized pigmentary T~OZ exhibits outstanding processibility in a polymeric matrix and lacing resistance when incorporated into a .
polyolefin matrix. Additional advantages observed are increased bulk density, lower viscosity, excellent dispersi'bility, moisture resistance, and excellent optical properties such as high tint strength.
, The following examples are construed as illustrative and not limitative of the remainder of the disclosure in arty way whatsoever. Farrel BIt >ganbury-type mixers (available from Farrel Corp., Aasonia, CT, USA) have been used in the Examples. Broad range internal mixers as known in the art arc contemplated equivalents. For exaatple, barrel Continuous Mixers (FCM) (available from )"noel Carp., Ansonia, Cl', USA) and twin screw extruders are equally applicable.
Bulk density is given as grams per cubic centimeter of uncompaeted pigment. A pigment bulk density below about 0.b will result in difCcult solids handling in polymer compounding. For rapid compounding of Ti02 and a polymer in a Banbury-type mixer, a bulk density above about~U.6 is desirable.
Total flux time is a measure of processing time, or time to disperse, in a Hanbury~-type mixer.
Viscosity, at 180 degrees Celsius, of product from the Banbury-type mixer, was measured at a shear rate of S501/sec. Viscosity was measured with a Kayeness capillary rheometer (available from Kayeness Corp., Honey Brook, PA, USA).

EXAMPLES
PREPARATION OF A CONCENTRA ~ P MA~TFu~te~rCu In the following examples, a 70 wt.% compound of a dry mix Ti02 balance polyethylene was prepared in the following manner. First, a dry mix of Ti02/balance polyethylene was prepared via blending of 1562 grams of the Ti02 with 670 grams of polyethylene. The polyethylene used for the experiments was a low density polyethylene supplied by Quantum U.S.I. Chemicals--Code = NA212 (Cincinnati, OH, USA).
The dry mix of Ti02/polyethylene was added to the feed hopper of a laboratory Farrel BR Banbury-type Mixer (chamber capacity = about 1100-about 1200 cc). The dry mix was then discharged into the Mixer. Stock pressure equaled 56 psi, driven rotor speed = 230 rpm, cooling water = 85°F. The Mixer was equipped with recording equipment for batch temperature, power consumption, ram pressure, and heat loss.
The mixture of Ti02/polyethylene was subsequently processed until the Ti02 dispersed into the melted resin (temperature=for example 220°F) defined above as total flux time. The compound was then discharged from the mixer.
3000 grams of neutralized pigmentary ruble Ti02 were weighed into a pan and sprayed with 30 grams of butyl trimethoxy silane, as supplied by Union Carbide now Osi Specialty, Inc. (Tarrytown, NY, USA).
The treated pigment was ground in a fluid energy mill, e.g., micronizer with superheated steam.
The micronized pigment was mixed in a Patterson-Kelley V-Blender with 30 grams of polydimethylsiloxane, as supplied by Petrach now Huls Corp.
(Piscataway, NJ, USA).
The treated Ti02 polyethylene concentrate was prepared as described above.
Same as Example 1 except that octyl triethoxy silane was used in place of butyl trimethoxy silane.

WO 95123192 PC'T/US95102811 ~ ' .

EXAMP1.F ~ ' Neutralized pigmentary ruble Ti02 was treated with about 1 wt% of each of octyl triethoxy silane and polydimethylsiloxane as for Example 1, except that these compounds were added at the micronizer, through existing nozzles in a grinding chamber. The treated pigment and low density polyethylene were then mixed and processed in a Banbury-type mixer to form a 70 wt% masterbatch, as described above.
,4 Neutralized pigmentary ruble Ti02 was treated with about 1 wt% of octyl triethoxy silane, by spraying, as for Example 1. There was no treatment with polydimethylsiloxane. The treated pigment was micronized, and used for processing in a Banbury-type mixer to a 70 wt% polyethylene masterbatch, as described above.
~OMP~R_A~ EXAMPLE 51~5~
Pigmentary ruble Ti02 and low density polyethylene were mixed and processed in a Banbury-type mixer to form a 70 wt% polyethylene masterbatch, as described above.
The results of the tests on the masterbatches from Examples 1-5 are summarized in the table below.
Bulk Total Density Flux Viscosity Example ~ ~ccl 1 0.96 26 3675 2 1.01 26.2 3681 3 0.78 24.5 3479 4 0.97 28.2 3927 C-5 0.54 37.6 4459 2' This data demonstrated the processing advantages of organosilicon compound treated pigments (Examples 1-4) versus a non-treated pigment (Example C-S) in a 70 wt.% Ti02/polyethylene masterbatch. Shown in the table are bulk density improvements realized by the organosilicon compound treatments, total flux time improvement, and viscosity improvements for these materials over non-treated.
Dried, crushed, meshed pigmentary ruble Ti02 filter cake was sprayed with about 1 wt. % of neat octyl triethoxy silane, as supplied by Osi.
The treated pigment was micronized and used for processing in a Banbury-type mixer to a 70 wt. % polyethylene masterbatch, as described above.
COMPA-R_ATIVE EKAMP .F ~A
Same as Example 6 except butyl trimethoxy silane was used in place of octyltriethoxysilane. The results of the tests on the masterbatches from Examples 6-6A are summarized in the table below.
Bulk Total Density Flux Viscosity Ea-amble ~/~ cc1 6 0.97 28 3927 6A 0.77 48 3921 This data demonstrated the differences for a higher chain alkyl silane (Example 6) versus a lower chain alkyl silane. Surprisingly, the lower chain alkyl silanes resulted in longer processing times. The lower chain alkyl silane realized a 70% increase in processing time over the higher chain alkyl silane.
nn~~tmr~ i 3000 grams of pigmentary rutile Ti02 was treated with 1 weight %
(30 grams) octyltriethoxysilane via spraying. Material was processed in a Banbury-type mixer at 70 weight % in a polyethylene masterbatch as described above.

3000 grams of pigmentary rutile Ti02 was treated with 1 weight %
(30 grams) polydimethylsiloxane (PDMS) via spraying. Material was processed in a WO 95123192 ~ ~ PCT/US95/02811 Banbury-type mixer at 70 weight % in a polyethylene masterbatch as described above.

Pigmentary rutile Ti02 was treated with 1 weight %
octadecyltriethoxy silane (available from Hull) via spraying: Material was processed in a Banbury-type mixer at 70 weight % in a polyethylene masterbatch as described above.
The results of tests on the masterbatches from Examples 7, 7A and 8 are summarized in the table below.
Bulk Total Density Flux Viscosity Example ..>~1 -l~ ~,pl 7 0.63 30.2 2968 7A 0.59 353 3491 8 0.58 33 2746 This data demonstrated a series of post-blended higher chain alkyl silane (Examples 7 and 8) and siloxane (Comparative Example 7A) treated materials. For the two silane treated materials (Examples 7 and 8) treated with a higher chain alkyl silane, final product viscosities were nearly identical.
For the siloxane only (Comparative Example 7A) treated material viscosity and processing time were higher.

Silanized pigment, octyltriethoxysilane, and polyester were dry blended in a double cone blender for 5 minutes to yield a 50/50 mixture. This mixture was added to a feed hopper of a Farrel Continuous Mixer (FCM). The mixture of treated Ti02/polyester was subsequently processed until the treated Ti02 dispersed into the melted resin (temperature=S50°F). Observable flow of the concentrate was smooth and continuous.

An untreated anatase pigment, I~ronos'~ 1072 (available from Kronas, L,everkuesen, f'xermany), was dry blended, fed and processed in the FCM as in Fatample 9. Observable flow of the concentrate was not smooth. Continnaus flow was not attained.
Lacing occurs as a function of pigarent volatility at specific wt 96 pigment loadings and provessing temperature. For polyethylene blurs pigmented v~nth tita~um dioaade, 20'wt ~b ~'i~ in the film processed at temperatures of 620'°'F
a~r greater will discern readily lacibdity of the film. ~pically, materials are rated 10 ii' they do not Iacx, and below 10 if they begin to lace.
'Iwo materials are compared in the following for lacing.
By weight, 209''0 of an octyltriethaxy silane treated TfOZ was etimpouaded into balance palyethylene. Material was extruded on a ICillion single screw extr~ider through a film die at 620°F. Evaluation of the filal on a light boy revealed superior integrity with no thin spots ox pin-holes. Rating of material equaled 10. Ladag resistance was comparable to the industry atandard,'I'i-Purem xt-101, available from E. I. du Pont de Nemours and Company, Wilm~.ngton, DE, ><JSA.
2S By weight, 20% of a sdoxane treated pigment RCLr69, (available from f~CM, Baltimore, MD, USA) wax compounded i~o balance polyethyleac. Material vvas extruded an s Kiliion single screw extruder through a film die at 620°F.
Material exh~ited thin spots under a tight box. Material was rated as a 7. ' Having thus described and exemplified the imrendon with a certain degree of particularity, it should be appreciated that the following claims'are not to tie so limited but are to be afforded a scope commensurate with the wording of each Element of the claim and equivalents thereof.

Claims (36)

CLAIMS:

1. A polymer matrix comprising polymer and about 50 to about 87% by weight silanized TiO2 pigment, based on the weight of the polymer matrix, exhibiting enhanced processibility, wherein the TiO2 pigment has a coating of about 0.1 to about 5% by weight, based on the weight of the silanized TiO2, of at least one organosilicon compound having the formula:

R x Si(R')4-x wherein R is a nonhydrolyzable aliphatic, cycloaliphatic or aromatic group having 8-20 carbon atoms;
R' is a hydrolyzable group selected from alkoxy, halogen, acetoxy or hydroxy or mixtures thereof; and;
x = 1 to 3.

2. A polymer matrix comprising polymer and about 50 to about 87% by weight silanized TiO2 pigment, based on the weight of the polymer matrix, wherein the silanized TiO2 pigment has a coating of about 0.1 to about 5% by weight, based on the weight of the silanized TiO2, of an organosilicon compound comprising a mixture of (a) and (b) wherein (a) is at least one silane having the formula:

R x Si(R')4-x wherein R is a nonhydrolyzable aliphatic, cycloaliphatic or aromatic group having 1-20 carbon atoms;
R' is a hydrolyzable group selected from alkoxy, halogen, acetoxy or hydroxy or mixtures thereof, and x = 1 to 3; and (b) is at least one polysiloxane having the formula:

wherein R is an organic or inorganic group;
n = 0-3; and m >= 2.

3. The composition of Claim 1 or Claim 2 wherein the polymer is polyolefin.

4. The composition of Claim 3 wherein the polyolefin is polyethylene.

5. The composition of Claim 1 or Claim 2 wherein the polymer is polyvinyl chloride.

6. The composition of Claim 1 wherein R is aliphatic having 8-18 carbons, R' is alkoxy and x =1 to 3.

7. The composition of Claim 2 wherein the mixture comprises the silane selected from the group consisting of butyltrimethoxysilane and octyltriethoxysilane and the siloxane is polydimethylsiloxane.

8. The composition of Claim 3 or Claim 4 wherein the silanized pigment is present in the amount of about 70 to about 82% by weight and the organosilicon compound is selected from the group consisting of octyltriethoxysilane, nonyltriethoxysilane, decyltriethoxysilane, dodecyltriethoxysilane, tridecyltriethoxysilane, tetradecyltriethoxysilane, pentadecyltriethoxysilane, hexadecyltriethoxysilane, heptadecyltriethoxysilane, octadecyltriethoxysilane, mixtures thereof and mixtures of butyltrimethoxysilane and polydimethylsiloxane and mixtures of octyltriethoxysilane and polydimethylsiloxane.

9. The polyolefin matrix of Claim 8 wherein the polymer is a polyolefin and (a) the polyolefin is polyethylene;
{b) the silanized TiO2 is TiO2 coated with about 0.5 to 1.5% by weight of an octyltriethoxysilane; and (c) the silanized TiO2 pigment is present in the amount of about 70% by weight.

10. The polethylene matrix of Claim 9 wherein the coating comprises about 1%
by weight of butyltrimethoxysilane and 1% by weight polydimethylsiloxane.

11. The polyethylene matrix of Claim 9 wherein the coating further comprises 1% by weight of polydimethylsiloxane.

12. A process for enhancing processability in compounding highly loaded TiO2 in a polymer matrix comprising the steps of:

(a) coating TiO2 with an organosilicon compound so that a chemical bond is formed; and (b) rapidly processing a high concentration of organosilicon coated TiO2 with a polymer in an internal mixer at increased flux time, wherein the organosilicon compound has the formula, R x Si(R')4-x whezein R is a nonhydrolyxable aliphatic, cycloaliphatic or aromatic group having 8-20 carbon atoms;
R' is a hydrolyzable group selected from alkoxy, halogen, acetoxy or hydroxy or mixtures thereof; and x = 1 to 3;

13. A process for enhancing processability in compounding highly loaded TiO2 in a polymer matrix comprising the steps of:
(a) coating TiO2 with an organosilicon compound so that a chemical bond is formed; and (b) rapidly processing a high concentration of organosilicon coated TiO2 with a polymer in an internal mixer at increased flux time, wherein the organosilicon compound comprises a mixture of (a) and (b) wherein, (a) is at least one silane having the formula:
R x Si(R')4-x wherein R is a nonhydrolyzable aliphatic, cycloaliphatic or aromatic group having 1-20 carbon atoms;
R' is a hydrolyzable group selected from alkoxy, halogen, acetoxy or hydroxy or mixtures thereof, and x = 1 to 3; and (b) is at least one polysiloxane having the formula:
wherein R is an organic or inorganic group;
n = 0-3; and m >= 2.

14. The process of Claim 12 or Claim 13 wherein (a) the polymer is polyolefin;
(b) the organosilicon compound is present in the amount of about 0.5 to about 5%
by weight; and (c) the high concentration of the TiO2 ranges from about 50 to about 82%.

15. A process for preparing a polyethylene composition comprising polyethylene and coated TiO2 pigment, comprising the steps of:
(a) coating TiO2 pigment with at least one organosilicon compound having the formula:
R x Si(R')4-x wherein R is a nonhydrolyzable aliphatic, cycloaliphatic or aromatic group having 8-20 carbon atoms;
R' is a hydrolyzable group selected from alkoxy, halogen, acetoxy or hydroxy or mixtures thereof; and x = 1 to 3 to form coated TiO2 pigment; and (b) mixing the coated TiO2 pigment with a polyethylene matrix at a concentration of about 50 to about 87% by weight of coated TiO2 pigment based on the weight of the polyethylene matrix to form a polyethylene composition consisting essentially of polyethylene and coated TiO2 pigment.

16. The process of claim 15 wherein the organosilicon compound is hydrolyzed and forms a bond with the TiO2 pigment.

17. A process for preparing a concentrate of a silanized TiO2 pigment in a polymer, comprising the steps of:
(a) treating TiO2 pigment with a silane compound having the formula:
R x Si(R')4-x wherein R is a nonhydrolyzabte aliphatic, cycloaliphatic or aromatic group having 8-20 carbon atoms;

R' is a hydrolyzable group selected from alkoxy, halogen, acetoxy or hydroxy or mixtures thereof; and x = 1 to 3 to form silanized TiO2 pigment; and (b) mixing the silanized TiO2 pigment with a polymer resin to form a highly loaded polymer concentrate comprising about 50 to about 87% by weight silanized TiO2 pigment.

18. The process of claim 17 wherein the TiO2 pigment is treated with a mixture of said silane compound and a polysiloxane compound.

19. The process of claim 18 wherein the polysiloxane compound has the formula:

wherein R is an organic or inorganic group;
n = 0-3; and m >= 2.

20. The process of any one of Claims 17 to 19 wherein the concentrate comprises about 70 to 87% by weight silanized TiO2 pigment.

21. The process of any one of Claims 17 to 19 wherein the silane compound is octyltrethoxysilane.

22. The process of any one of Claims 17 to 19, wherein in the general formula of the silane R is an aliphatic having 8-18 carbons, R' is methoxy, ethoxy, chloro, hydroxy, or mixtures thereof and x = 1 to 3.

23. The process of any one of Claims 17 to 19 wherein the polymer is selected from the group consisting of polyolefins, polyesters, polyvinyl chlorides and polystyrene.

24. The process of Claim 20 wherein the polymer resin is polyethylene, polypropylene, or polybutylene.

25. The process of any one of Claims 17 to 24 wherein the silane treatment is made in step (a) to pigment from a slurry.

26. The process of any one of Claims 17 to 24 wherein the silane is added in step (a) to TiO2 pigment during drying.

27. The process of any one of Claims 17 to 24 wherein the silane is prehydrolyzed prior to treating the TiO2 pigment.

28. A polymer concentrate comprising:
(a) a polymer, and (b) about 50 to 87% by weight of silanized TiO2 pigment, based on the weight of polymer concentrate, wherein the silanized TiO2 pigment is obtained by treating the pigment with the reaction products of water ana a silane compound having the formula:

R x Si(R')4-x wherein R is a nonhydrolyzable aliphatic, cycloaliphatic or aromatic group having 8-20 carbon atoms;
R' is a hydrolyzable group selected from alkoxy, halogen, acetoxy or hydroxy or mixtures thereof; and x=1 to3.

29. The polymer concentrate of Claim 28 comprising about 70 to 87% by weight of silanized TiO2 pigment.

30. The polymer concentrate of Claim 28 wherein the silane compound is octyltriethoxysilane.

31. The polymer concentrate of Claim 28 wherein R is an aliphatic group having 8 to 18 carbon atoms and R' is methoxy, ethoxy, chloro, hydroxy or mixtures thereof and x = 1 to 3.

32. The polymer concentrate of Claim 31, wherein R is an aliphatic group of 8 carbon atoms.

33. The polymer concentrate of Claim 28 wherein the polymer is a polyolefin, polyester, polyvinyl chloride or polystyrene.

34. The polymer concentrate of Claim 33 wherein the polyolefin is polethylene, polypropylene or polybutylene.

35. The polymer concentrate of Claim 28 wherein the TiO2 pigment is silanized with about 0.1 to about 5% by weight of the silane compound based on the weight of the TiO2 pigment.

36. A process for preparing a pigmented polymer composition which comprises preparing a polymer concentrate as claimed in any one of Claims 28 to 35, and letting down the concentrate by addition of polymer to form a composition containing about 0.2 to about 20 weight percent of silanized TiO2 pigment.