Document jgGYVD0aRnXGoE655gLv21ZvQ

BROOKES & RT1N CHARTERED PATENT AGENTS TRADE MARK AGENTS EUROPEAN PATENT ATTORNEYS RICHARD C. MARTIN, M.A,C*NTA. DAVID C- WOODCRAFT, ERIC E. BARNARD. C.CMO-,*O.E.E.1C.Oi. A.r. GRAHAM F. MATTHEWS, B.A., C.En o , F.I.E.C. JOHN F. SYMONDS, LL.S.Lo mo ., SOLICITOR JOHN H. BLAKE. HUGH R. WRIGHT, M.A.CXO*. PETER C. SANDERS. S.Se. H. NICHOLAS MATTHEWS. M.lNST. T.M.A. DONALD J. ATTFJELD. a.Sc. C.Ch c m. M.R.S.C. Of f ic e Ma n a o c R - A. J. JELLY Ac c o u n t s -Mns C.OLSINIA The European Patent Office Erhardstrasse 27 D-8000 Munchen 2 Federal Republic of Germany TEIXX 267541 TELEPHONES (Ol) 242 @631 FACSIMILE {Oil 631 0586 LDX 318 HIGH HOLBORN HOUSE 52/54,HIGH HOLBORN LONDON, WC1V 6SE OUR REF DCW/VSW/ CH1370 5 January 1990 Dear Sirs, European Patent Application No. 87 303 682.6 E. I. DU PONT DE NEMOURS AND COMPANY I refer to the official letter dated 12 October 1989 and file herewith amended copies of the claims in triplicate. It is noted that the Examiner has reviewed the prior art and agrees that the various prior art has already been acknowledged in the application. It is also noted that the Examiner shares the applicants' view that the present claims define a pigment and a method for its production which meets the requirements of Articles 54 and 56 EPC. With regard to paragraph 2 of the official action, the claims are intended to include materials in the coatings such as alumina, which is conventionally added in order to improve processing properties. In this connection, the Examiner's attention is directed to page 5, line 29, to page 6, line 7, and to page 6, lines 31 to 36. In order to make it clear that the coatings may contain other components, the term "comprising" has been substituted for the term "consisting essentially of", for example, in line 2 of claim 2. Yours faithfully. DAVID C. WOODCRAFT BROOKES MARTIN TUMBRIOGE WELLS: I BOYNE PARK. TUNBRIDGE WELLS. KENT. TN4 BEL. TEL. IOS92) 510600 TELEX 957078 FACSIMILE (06921 510666 BIRMINGHAM' PRUDENTIAL BUILDINGS. 6 ST. PHILIPS PLACE. BIRMINGHAM. B3 2AF. TEL. (021} 238 6262 TEuEX 336361 FACSIMILE (021) 2001473 MUNICH* 15 ZWEIBRUCKCNSTRASSC, 6000 MUNICH 22. TEL. (06 9) 22 20 IQ N 30927 1 CLAIMS 1. A pigment comprising rutile Ti02 bearing coatings comprising Si02 and B2O3. particles 2. A pigment according to claim 1, wherein the Ti02 particles have coatings comprising from 60-98 percent by weight Si02 and 0.5-30 percent by weight B2O3 based on coating weight. 3. A pigment according to claim 2, wherein the Ti02 particles have coatings comprising from 80-90 percent by weight Si02 and 2-20 percent by weight B203, based on coating weight. 4. A pigment according to claim 3, wherein the Ti02 particles have Si02/B203 coatings constituting 2-10% of the total pigment weight. 5. A pigment according to claim 4. wherein the T'i02 particles have Si02/B203 coatings constituting 4-8% of the total pigment weight. 6. A pigment according to any one of the preceding claims, wherein the Ti02 particles have outer coatings of alumina constituting 0.5-5% of the total weight of the particles. 7. A pigment according to claim 6, wherein the Ti02 particles have outer coatings of alumina constituting 1-4% of the total weight of the particles. 8. A process for preparing Ti02 particles coatings of boria-modified silica, comprising: bearing (a) forming an aqueous slurry of rutile Ti02 at a temperature from about 65 to about 90C; N 30927.01 DUP050449404 2 (b) adjusting pH of the slurry to the range 7-10.5; (c) adding a predetermined quantity of a solution comprising Na2Si03 and B203, under conditions which maintain silicate and boria ions in solution; (d) gradually lowering pH of the slurry to abut 7.5-8.5 by addition of acid, thereby depositing a coating of silica and boria; and (e) curing the resulting coated pigment temperature of from about 65C to abut 90C period of at least 15 minutes. at for a a 9. A process according to claim 8, wherein sufficient Na2Si03 and B203 are added in step (c) to provide a coating comprising from 60-98 percent by weight Si02 and 0.5-30 percent by weight B203 based on coating weight. 10. A process according to claim 9, wherein sufficient Na2Si03 ant3 B23 are a(3ded in step (c) to provide a coating comprising from 80-90 percent by weight Si02 and 2-20 percent by weight B203, based on coating weight. 11. A process according to claim 10, sufficient Na2Si03 and B203 are added in step provide a Si02/B2C>3 coating constituting 0.5-10% total pigment weight. wherein (c) to of the 12. A process according to claim 11, wherein sufficient Na2SiC>3 and B203 are added in step (c) to provide a Si02/B2C>3 coating constituting 4-8% of the total pigment weight. DUP050449405