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1. (WO2019002162) BRIN DE RENFORT POUR RENFORCER UN ARTICLE POLYMÈRE
Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

Claims

1 . A reinforcement strand for reinforcing a polymer article, said reinforcement strand comprising a core having a core diameter and steel filaments, said steel filaments being organised in

- an intermediate layer comprising N first steel filaments circumferentially arranged around said core, said first steel filaments having a first diameter, said core diameter and said first diameter being such that a gap forms between said first steel filaments and

- an outer layer comprising 2N steel filaments circumferentially arranged around said intermediate layer,

said steel filaments of said intermediate layer and said outer layer being twisted around said core with the same final lay length and direction

characterised in that

said final lay length is larger than two times and smaller than six times the closing lay length, said closing lay length being that lay length at which the gap between said first filaments of the intermediate layer is closed.

2. The reinforcement strand according to claim 1 wherein there is no gap between the filaments of the outer layer at final lay length.

3. The reinforcement strand according to any one of claims 1 or 2 wherein said outer layer comprises

- N second steel filaments of a second diameter, said N second steel filaments being tangent to a second circumscribing circle having a second radius and

- N third steel filaments of a third diameter, said N third steel filaments being tangent to a third circumscribing circle having a third radius said second diameter being larger than said third diameter, said second steel filaments and said third steel filaments occupy alternating positions in said outer layer, and wherein the second radius is different from the third radius.

4. The reinforcement strand according to claim 3 wherein the second radius is larger than the third radius.

5. The reinforcement strand according to any one of claims 1 to 4 wherein N is equal to 5, 6, 7, 8 or 9.

6. The reinforcement strand according to any one of claims 1 to 5 wherein said core is a single steel filament comprising bends with straight segments in between.

7. The reinforcement strand according to any one of claims 1 to 5 wherein said core is an equal lay strand wherein all core steel filaments are free from zero order helical deformations and are twisted together with a core lay length different from the final lay length of said reinforcement strand.

8. The reinforcement strand according to claim 7 wherein the number of core steel filaments is two or three or four and said core steel filaments have an equal diameter.

9. The reinforcement strand according to claim 7 wherein the number of core steel filaments is nine or twelve and wherein the core steel filaments are arranged in a semi-Warrington construction.

10. The reinforcement strand according to any one of claims 1 to 5 wherein said core is a strand comprising a core-core and 5, 6 or 7 core outer steel filaments twisted around said core-core with a core lay length different from the final lay length of said reinforcement strand.

1 1 .The reinforcement strand according to any one of claims 1 to 10 wherein said steel filaments of said reinforcement strand are provided with a metallic coating or metallic coating alloy.

12. The reinforcement strand according to any one of claims 1 to 1 1 wherein said reinforcement strand is provided with an organic primer that promotes adhesion to a polymer.

13. The reinforcement strand according to claim 12 wherein said organic primer is one out of the group comprising organo functional silanes, organo functional zirconates or organo functional titanates.

14. A method of manufacturing a reinforcement strand comprising the steps of:

- Providing a core having a core diameter;

- Providing N first steel filaments having a first diameter;

- Providing N second steel filaments having a second diameter, larger than said first diameter;

- Providing N third steel filaments having a third diameter

- Twisting said core, said N first steel filaments, said N second steel

filaments and said N third steel filaments together in one lay direction to final lay length, wherein said N first steel filaments form an intermediate layer, said N second and N third steel filaments form an outer layer, said N second and N third layer steel filaments occupying alternating positions in said outer layer;

characterised in that

during said twisting, the intermediate lay length of first, second and third steel filaments is shortened to between the closing lay length and 83% of the final lay length and thereafter the first, second and third steel filaments are untwisted to said final lay length, whereby said intermediate lay length remains larger than or equal to the closing lay length, said closing lay length being that lay length at which the first steel filaments in said intermediate layer touch one another.

15. The method of claim 14 wherein at the intermediate lay length the second and third steel filaments of the outer layer are radially compressed towards said intermediate layer.

16. The reinforcement strand produced according the method of claim 14 or 15 characterised in that, upon cutting the reinforcement strand thereby forming a reinforcement strand end, at least said first steel filaments of said intermediate layer retract into reinforcement strand end.