Durable powder composition

Abstract

The present invention relates to a detoxified powder composition comprising a zinc-bearing compound selected from the group consisting of zinc carbonate, zinc hydroxide, zinc oxide, zinc sulphate and mixtures thereof, and at least one detoxification agent containing at least one oxide based on a cation, selected from the group consisting of calcium, barium, magnesium, strontium and beryllium.

Claims

1. A detoxified powder composition suitable for use as a vulcanization agent for rubber, comprising a zinc-bearing compound selected from the group consisting of zinc carbonate, zinc hydroxide, zinc oxide, zinc sulphate and mixtures thereof, and at least one detoxification agent being magnesium oxide, wherein the composition comprises between 92.5 and 99.5% by weight of said zinc-bearing compound and between 0.5 and 7.5% by weight of magnesium oxide with respect to the total weight of the composition, wherein the composition has a specific surface area less than 80 m.sup.2/g, and wherein the zinc-bearing compound has a specific surface area greater than 30 m.sup.2/g, as measured by physical adsorption according to the B.E.T method (Brunauer-Emmett-Taylor).

2. The composition according to claim 1, wherein the composition has a particle size d50 comprised within a range from 0.5 to 20 μm, as measured by laser granulometry with ultrasounds, where the dispersant is water.

3. A vulcanizing agent comprising the composition according to claim 1.

4. A method for producing a detoxified powder composition, the method comprising: mixing between 92.5% and 99.5% by weight of a zinc-bearing compound selected from the group consisting of zinc carbonate, zinc hydroxide, zinc oxide, zinc sulphate and mixtures thereof, with between 0.5% and 7.5% by weight of magnesium oxide with respect to the total weight of the composition to provide the detoxified powder composition, wherein the composition has a specific surface area less than 80 m.sup.2/g and wherein the zinc-bearing compound has a specific surface area greater than 30 m2/g, as measured by physical adsorption according to the B.E.T method (Brunauer-Emmett-Taylor).

5. The method according to claim 4, wherein said zinc-bearing compound is zinc oxide obtained by wet processes which has a nodular morphology.

6. The method according to claim 4, wherein said composition has a particle size d50 comprised within a range from 0.5 to 20 μm measured by laser granulometry.

7. The method according to claim 4, wherein said zinc-bearing compound is zinc oxide and wherein the detoxification agent is magnesium oxide.

8. The method according to claim 4, wherein the composition is micronized.

Description

EXAMPLE 1

(1) A composition according to a first production method is obtained by mixing 99% by weight of zinc oxide with 1% by weight of magnesium oxide.

(2) The acute ecotoxicity results on Oncorhynchus mykiss fish are illustrated in table 2, which illustrates that no trout had died. The preparation has no toxicity for fish, due to an acute ecotoxicity CE50>100 mg/L, according to the OECD 203 protocol, dated 17 Jul. 1992.

(3) TABLE-US-00002 TABLE 2 NUMBER GLP/NON- OF TROUT CE50 PREPARATION GPL TEST TROUT MORTALITY (MG/L) ZA 99 NON-GLP 10 0 >100

(4) The acute ecotoxicity results on Daphnia magna crustaceans are illustrated in table 3 below, which illustrates that no Daphnia has been immobilised. The preparation therefore has no toxicity for crustaceans due to an acute ecotoxicity CE50>100 mg/L, according to the OECD 202 protocol, dated 13 Apr. 2004.

(5) TABLE-US-00003 TABLE 3 GLP/NON- DAPHNIA PREPARATION GLP TEST IMMOBILISATION CE50 (MG/L) ZA 99 NON-GLP 0 >100

(6) The acute ecotoxicity results on Pseudokirchneriella subcapitata algae are illustrated in table 4 below, which illustrates that the inhibition of algae is between 10 and 100 mg/l, according to the OECD 201 protocol, dated 23 Mar. 2006. Using this preparation does not therefore require any labelling on the packaging.

(7) TABLE-US-00004 TABLE 4 GLP/NON- PREPARATION GLP TEST CI50 (MG/L) ZA 99 NON-GLP COMPRISED BETWEEN 10 AND 100

EXAMPLE 2

(8) A composition according to a second embodiment has been obtained by mixing 99% by weight of zinc oxide with 1% by weight of magnesium oxide.

(9) Table 5 illustrates the ecotoxicity results on fish, Daphnia and algae, respectively based on the OECD 203, OECD 202 and OECD 201 protocols.

(10) In the three cases, the composition has no toxicity due to an acute ecotoxicity CE50 or CL50 or ErC50>100 mg/L.

(11) TABLE-US-00005 TABLE 5 Tests Results CL50 fish >100 mg/l (96 hours) CE50 daphnia >100 mg/l (48 hours) ErC50 (algae) >100 mg/l (72 hours) NOEC (chronic)  >1 mg/l (21 days)

EXAMPLE 3

(12) Example 3 relates to the formation of a rubber vulcanising agent by means of the composition according to the invention.

(13) According to table 6, the following compounds are mixed: 75 phr of ethylene-propylene-diene monomer rubber (EPDM 9500), 25 phr ethylene-propylene-diene monomer (EPDM 2504), 2 phr stearic acid, 5 phr of the composition according to the invention, 0.5 phr of 2,2,4-Trimethyl-1,2-Dihydroquinoline (TMQ, antioxidant), 140 phr of a charge containing black carbon, 85 phr of paraffinic oil, 0.8 phr of 2-Mercaptobenzothiazole (MBT), 0.6 phr of zinc ethylene-bis-dithiocarbamate (ZEDC), 0.6 phr of zinc dibutyl-dithiocarbamate (ZBDC), 0.6 phr of dithiodimorpholine (DTDM) and 0.6 phr of sulphur. The 5 phrs of the composition according to the invention comprise around 99% by weight of ZnO and around 1% by weight of MgO (the remainder being formed by impurities or inactive elements in the composition). In other words, 4.95 phr of ZnO and 0.05 phr of MgO form the composition according to the invention.

(14) TABLE-US-00006 TABLE 6 Formulation phr EPDM 9500 75 EPDM 2504 25 Stearic acid 2 Composition 5 according to the invention TMQ 0.5 Black FEF 550 140 Paraffinic Oil 85 MBT 0.8 ZEDC 0.6 ZBDC 0.6 DTDM 0.6 Sulphur 0.6

(15) It is understood that the present invention is, in no manner, limited to the embodiments described above and that modifications can be applied to them, without moving away from the scope of the appended claims.