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1. (WO2019066732) A METHOD FOR MOLD-FREE MANUFACTURING OF NATURAL RUBBER ARTICLES
Nota: Texto obtenido mediante procedimiento automático de reconocimiento óptico de caracteres.
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Claims:

1. A method of forming a three-dimensional object, comprising;

(a) preparing prevulcanized natural rubber latex.

(b) adding processing aid into the prevulcanized natural rubber latex for obtaining the mixture of prevulcanized natural rubber latex and processing aid.

(c) fabricating the mixture of prevulcanized natural rubber latex and processing aid to three-dimensional rubber articles by stereolithography (SLA) process.

2. The method of claim 1, wherein a composition for preparing prevulcanized natural rubber latex comprising natural rubber latex which has dry rubber content in the range of 30-60 wt%.

3. The method of claim 1 or 2, wherein said preparing prevulcanized natural rubber latex is selected from sulfur prevulcanization system, peroxide prevulcanization system, and irradiation prevulcanization system.

4. The method of claim 3, wherein said irradiation prevulcanization system is selected from electron beam, gamma ray, ultraviolet wave, infrared wave, microwave, radio wave, and combination thereof.

5. The method of claim 3, wherein a composition for preparing prevulcanized natural rubber latex in sulfur prevulcanization system comprising natural rubber latex, sulfur, zinc oxide, accelerators, and antidegradants.

6. The method of claim 5, wherein a suitable composition for preparing prevulcanized natural rubber latex in sulfur prevulcanization system, comprising;

a. natural rubber latex,

b. sulfur is in the range of 0.1 - 5.0 parts per 100 parts by weight of dry rubber content (phr),

c. zinc oxide is in the range of 0.1 - 5.0 phr,

d. accelerators) is in the range of 0.1 - 3.0 phr, and

e. antidegradant(s) is in the range of 0.1 - 5.0 phr.

7. The method of claim 6, wherein said accelerator(s) is selected from the group consisting of dithiocarbamates, thiurams, guanidines, and combination thereof.

8. The method of claim 7, wherein said dithiocarbamate(s) is selected from the group consisting of zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibenzyldithiocarbamate, and combination thereof.

9. The method of claim 7, wherein said thiuram(s) is selected from the group consisting of tetramethyl thiuram monosulphide, tetramethyl thiuram disulphide, tetraethyl thiuram disulphide, and combination thereof.

10. The method of claim 7, wherein said guanidine(s) is selected from the group consisting of diphenyl guanidine, di-o-tolyl guanidine, and combination thereof.

11. The method of any one of claim 3 to 10, wherein said sulfur prevulcanization system carries out at temperature of 50 - 70 °C for 1 - 5 hours.

12. The method of claim 4, wherein a composition for preparing the prevulcanized natural rubber latex in the irradiation prevulcanization system via ultraviolet wave, comprising; a. natural rubber latex,

b. initiator(s) is in the range of 0.1 - 5.0 parts per 100 parts by weight of dry rubber content (phr),

c. coagent(s) is in the range of 0.1 - 5.0 phr, and

d. antidegradant(s) is in the range of 0.1 - 5.0 phr.

13. The method of claim 12, wherein said initiator(s) is selected from the group consisting of a-hydroxyketone, phenylglyoxylate, a-aminoketone, phosphine oxide, metallocene, benzophenone, and combination thereof.

14. The method of claim 13, wherein said a-hydroxyketone is selected from the group consisting of 2-hydroxy-2-methyl-l -phenyl- 1-propanone, 1-hydroxycyclohexyl phenyl ketone, and combination thereof.

15. The method of claim 13, wherein said phenylglyoxylate is selected from the group consisting of methyl benzoylformate, oxy-phenyl-acetic 2 - [2-hydroxy-ethoxy]-ethyl ester, and combination thereof.

16. The method of claim 13, wherein said a-aminoketone is selected from the group consisting of 2-benzyl-2-(dimethylamino)- 1 -[4-(4-morpholinyl)phenyl]- 1 -butanone, 2-methyl- 1 -[4- (methylthio)phenyl] -2-(4-morpholinyl)- 1-propanone, and combination thereof.

17. The method of claim 13, wherein said phosphine oxide(s) is selected from the group consisting of diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide, dimethyl (phenyl)- phosphine oxide, butyl(diphenyl)-phosphine oxide, and combination thereof.

18. The method of claim 13, wherein said metallocene(s) is selected from the group consisting of titanocenes, ferrocenes, zirconocenes, and combination thereof.

19. The method of claim 12, wherein said coagent(s) is selected from the group consisting of mono-functional groups, di-functional groups, tri-functional groups, multi-functional groups, and combination thereof.

20. The method of claim 19, wherein said mono-functional groups are selected from the group consisting of normal-butyl acrylate, methyl methacrylate, pheonoxy ethyl acrylate, hydroxyethyl methacrylate, pheonoxy polyethylene glycol acrylate, and combination thereof.

21. The method of claim 19, wherein said di-functional groups are selected from the group consisting of 1,9-nonanediol diacrylate, dimethylamino ethyl methacrylate, trimethylene glycol dimethacrylate, and combination thereof.

22. The method of claim 19, wherein said tri-functional groups are selected from the group consisting of trimethylol propane triacrylate, trimethylol propane trimethacrylate, triallyl cyanurate, and combination thereof.

23. The method of claim 19, wherein said multi-functional groups are selected from the group consisting of tetramethylol methane tetraacrylate, pentaerythritol teraacrylate, and combination thereof.

24. The method of claim 12, wherein said antidegradant(s) is selected from the group

consisting of amine derivatives, phenol derivatives, and combination thereof.

25. The method of claim 24, wherein said amine derivative(s) is selected from the group consisting of N-isopropyl-N'-phenyl-p-phenylenediamine, N-(l,3-dimethylbutyl)-N'- phenyl-p-phenylenediamine, 2,2,4-trimethyl-l,2-dihydroquinoline, and combination thereof.

26. The method of claim 24, wherein said phenol derivative(s) is selected from the group consisting of 2,6-di-tert-butyl-p-cresol, poly(dicyclopentadiene-co-p-cresol), 4,4'- butylidene-bis-(2-tert-arylbutyl-5-methylphenol) , and combination thereof.

27. The method of claim 1, wherein said processing aid is selected from the group consisting of heat sensitive polymers, carbon materials, and combination thereof.

28. The method of claim 27, wherein said heat sensitive polymer(s) is selected from the group consisting of a poly(N-isopropylacrylamide), poly(N-acryloyl glycinamide), poly[2- (dimethylamind)ethyl methacrylate], polyhydroxyethylmethacrylate, polyethylene oxide, hydroxypropylcellulose, poly(vinylcaprolactam), polyvinyl methyl ether, poly(N- vinylimidazole-co- 1 -vinyl-2-(hydroxymethyl)imidazole), poly (acrylonitrile-co- acrylamide), and combination thereof.

29. The method of claim 27 or 28, wherein an amount of said heat sensitive polymer(s) is in the range of 0.1 - 5.0 parts per 100 parts by weight of dry rubber content.

30. The method of any one of claim 27 to 29, wherein said heat sensitive polymer(s) is mixed into the prevulcanized natural rubber latex at the temperature of 10 - 25 °C for 15 - 60 minutes.

31. The method of claim 27, wherein said carbon material(s) is selected from the group consisting of graphite, graphene, carbon black, carbon nanotube, and combination thereof.

32. The method of claim 27 or 31, wherein an amount of said carbon material(s) is in the range of 0.5 - 20.0 parts per 100 parts by weight of dry rubber content.

33. The method of any one of claim 27 to 32, wherein said carbon material(s) is in the form of powder or colloidal solution.

34. The method of claim 1, wherein said prevulcanized natural rubber latex having a chloroform number in the range of 3 - 4 and/or a swelling index of more than 85%.

35. The method of claim 1, wherein said fabricating of three-dimensional rubber articles of stereolithography (SLA) process comprising the steps of;

(i) creating a 50 - 500 μηι thick layer of the mixture of prevulcanized natural rubber latex and processing aid on a substrate or a previous layer,

(ii) irradiating the layer of the mixture of prevulcanized natural rubber latex and processing aid with laser beam, and

(iii) repeating the i) - ii) steps until the three-dimensional article is completed.

36. The method of claim 35, wherein a laser wavelength is in the ranges of 200 - 450 nm (ultraviolet range) or 700 nm - 1 mm (infrared range).

37. The method of claim 35 or 36, wherein said irradiating has suitable parameters;

(i) pulse frequency of the laser is in the range of 20 - 100 kHz.

(ii) scan speed of the laser is in the range of 50 - 200 mm/s.

(iii) hatch space of the laser is in the range of 100 - 300 μηι.

(iv) power density of the laser in the range of 70 - 250 W7cm2.

38. The method of any one of claim 1 to 37, further comprising the step of cleaning and removing the excess liquid prevulcanized natural rubber latex in three-dimensional rubber articles by spraying or soaking the article with solvents or surfactant solutions.

39. The method of any one of claim 1 to 38, further comprising the step of drying the three- dimensional article at a temperature of 70 - 120 °C for 1 - 4 hours.