Composition for latex pad, producing method thereof, and the latex pads made therefrom

Abstract

The present invention relates to a composition for preparation of latex pads, comprising natural latex, artificial latex, sliver nanoparticles, zinc oxide nanoparticles, and active carbon mixed in a specified proportion. The present invention also provides a method for manufacturing latex pads from the composition.

Claims

1. A latex pad produced by a method comprising the steps of: step 1: mixing 20 parts by weight of a natural latex with about 50% moisture content and 80 parts by weight of an artificial latex with about 40% moisture content in an agitating machine at a stirring speed of 1200 rpm for 20 minutes to obtain a mixture of latexes; step 2: adding silver nanoparticles to the mixture of latexes obtained in step 1 at a proportion of about 3% by weight based on 100% by weight of the mixture of latexes, and stirring continuously at a speed of 1200 rpm for 30 minutes until the silver nanoparticles are evenly dispersed in the latexes to form a nano silver-latex mixture; step 3: adding zinc oxide nanoparticles to the nano silver-latex mixture obtained in step 2 at a proportion of about 5.15% by weight based on 100% by weight of the mixture of latexes, and stirring continuously at a speed of 1200 rpm for 15 minutes until the zinc oxide nanoparticles are evenly dispersed in the latexes to form a nano zinc oxide-nano silver-latex mixture; step 4: adding active carbon to the nano zinc oxide-nano silver-latex mixture obtained in step 3 at a proportion of about 5.41% by weight based on 100% by weight of the mixture of latexes, and stirring at a speed of 1200-1600 rpm for 6 minutes to form an active carbon-nano zinc oxide-nano silver-latex mixture; step 5: adding a vulcanizing promoter to the active carbon-nano zinc oxide-nano silver-latex mixture obtained in step 4 at a proportion of about 5.68% by weight based on 100% by weight of the mixture of latexes, and stirring at a speed of 1200-1600 rpm for 5 minutes to form a composition for producing a latex pad; step 6: pouring the composition prepared in step 5 into a storage tank, and subjecting it to a foaming process to form a foamed material; step 7: pouring the foamed material obtained in step 6 into a coating machine, then plating the foamed material onto a conveying platform via the coating machine, and leveling down the plated foamed material by scraping; step 8: transferring the scraped foamed material obtained in step 7 into a high temperature oven by the conveying platform at a speed of 3 m/min, and solidifying the surface of the foamed material at 265° C. to form a surface fixed material; step 9: transferring the surface fixed material obtained in step 8 into an oven by the conveying platform at a speed of 3 m/min, and bake ripening the material at 165° C. to form a ripened material; step 10: transferring the ripened material obtained in step 9 into a cold roller by the conveying platform at a speed of 3 m/min, and carrying out pressure roll cooling process at 20° C. to form a latex pad; step 11: covering the latex pad obtained in step 10 with an isolation membrane made of polyethylene, and winding the latex pad together with the isolation membrane into a coil of latex pad, wherein the latex pad comprises 20 parts by weight of natural latex and 80 parts by weight of artificial latex; said latex pad further including 3.00% by weight of silver nanoparticles, 5.15% by weight of zinc oxide nanoparticles, 5.41% by weight of active carbon, and 5.68% by weight of the vulcanizing promoter, based on 100% by weight of the natural and artificial latexes.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The other characteristics and advantages of the present invention will be further illustrated and described in the following examples. The examples described herein are using for illustrations, not to limit the scope of the invention.

(2) In the present disclosure, the composition for latex pad comprises natural latex, artificial latex, sliver nanoparticles, zinc oxide nanoparticles, and active carbon, wherein the moisture content of water contained in the natural latex and the artificial latex is 50% and 40%, respectively.

(3) The composition for latex pad of this invention is prepared by a method comprising: step 1, mixing the natural latex and the artificial latex at a proportion of 20% to 80% (by weight) in an agitating machine at a stirring speed of 1200 rpm for 20 minutes; step 2, adding sliver nanoparticles to the mixture of latex materials obtained in step 1 at a proportion of 3% (by weight) to the total weight of the latex material mixture, and stirring continuously at a speed of 1200 rpm for 30 minutes until the sliver nanoparticles are evenly dispersed in the latex materials to form a nano silver-latex mixed material; step 3, adding zinc oxide nanoparticles to the nano silver-latex mixed material obtained in step 2 at a proportion of 5% (by weight) to the total weight of the nano silver-latex material mixture, and stirring continuously at a speed of 1200 rpm for 15 minutes until the zinc oxide nanoparticles are evenly dispersed in the latex materials to form a nano zinc oxide-nano silver-latex mixed material; step 4, adding active carbon to the nano zinc oxide-nano silver-latex mixed material obtained in step 3 at a proportion of 5% (by weight) to the total weight of the nano zinc oxide-nano silver-latex material mixture, and stirring at a speed of 1200-1600 rpm for 6 minutes to form an active carbon-nano zinc oxide-nano silver-latex mixed material; and step 5, adding a vulcanizing promoter to the active carbon-nano zinc oxide-nano silver-latex mixed material at a proportion of 5% (by weight) to the total weight of the active carbon-nano zinc oxide-nano silver-latex material mixture, and stirring at a speed of 1200-1600 rpm for 5 minutes to form the composition for producing latex pads. The vulcanizing promoter added in the composition may be a nitrogen- and/or sulfur-containing organic compound, such as aldehyde amines, guanidines, tetraethylthiuram disulfides, thiazoles, disulfo-carbamates, xanthates, thioureas and sulfonamides, used alone or in combination.

(4) In certain embodiments of the disclosure, the composition comprises following components in proportion of: 20% by weight of natural latex containing 50% moisture content; 80% by weight of artificial latex containing 40% moisture content; 3% by weight of sliver nanoparticles, based on the total weight of the mixture of the latex materials; 5% by weight of zinc oxide nanoparticles, based on the total weight of the mixture of the latex materials and the sliver nanoparticles; 5% by weight of active carbon, based on the total weight of the mixture of the latex materials, the sliver nanoparticles and the zinc oxide nanoparticles; and 5% by weight of a vulcanizing promoter, based on the total weight of the mixture of the latex materials, the sliver nanoparticles, the zinc oxide nanoparticles and active carbon.

(5) In the composition of the present invention, the moisture content in the natural latex and the artificial latex is set to be 50% and 40%, respectively. These settings for the moisture content in latex materials are beneficial to the incorporation of active carbon, which will largely reduce the moisture content in such latex materials because of the moisture absorption property of active carbon. Consequently, the decrease in the moisture content of latex materials will cause difficulty in stirring, and even an aggregate of the latex materials. To avoid the problem of adding active carbon described above and ensure sufficient dispersion of active carbon in latex materials, the moisture content in individual latex material is specified for maintaining proper water content in the final composition after the incorporation of active carbon. Moreover, the high moisture content in latex materials is also facilitates easier stirring and mixing for the addition of sliver and zinc oxide nanoparticles, which can prevent agglomeration of such nanoparticles while causing them to be homogeneously dispersed in the present composition.

(6) The incorporation of sliver nanoparticles in the present composition is aimed to confer an anti-bacterial (or microbial inhibiting) efficacy to the latex pad product.

(7) The presence of zinc oxide nanoparticles in the present composition exhibits enhancing effects in sulfurization activity to increase crosslink densities of the latex materials, and improve mechanical properties of the present composition, such as extensibility, ductility resistance and tear resistance. Meanwhile, latex pad products made from present composition will possess properties of high cleanliness, temperature resistance, aging resistance, wear resistance, functions of bacterial killing, temperature lowering, warming, and producing capacity of far-infrared ray and negative ions.

(8) The purpose of incorporating active carbon is to confer improved properties of moisture absorption, deodorization, mildew proofing, microbial inhibiting and ventilating upon the latex pad products made from present composition. It is noticeable that the proportion of added active carbon in the present composition is increased to 5% by weight, as compared to the active carbon content of 2% by weight in previous products.

(9) An exemplary producing method of latex pads using the present composition comprises the following steps.

(10) (1) Foaming step, the composition prepared as described above in the disclosure is poured into a storage tank, and subjected to a foaming process to form a foamed material.

(11) (2) Plating step, the foamed material is poured into a coating machine, and then plated onto a conveying platform by the coating machine and leveled down by scraping, and the coating thickness is adjusted as needed.

(12) (3) First rapid-shaping step at high temperature, the scraped foamed material is transferred into a high temperature oven by the conveying platform at a speed of 3 m/min, and the surface of the foamed material is solidified to form a surface fixed material at 265° C. In this step, the speed of ripening latex materials induced by the vulcanizing promoter is reduced by the incorporated active carbon. Thus, the foamed material is transferred at a relatively lower speed (as compared to a traditional transferring speed of 5 m/min) into a relatively higher temperature oven (as compared to a traditional working temperature of 250° C.).

(13) (4) Second ripening step, the surface fixed material is transferred into an oven by the conveying platform at a speed of 3 m/min, and baked at a ripening temperature of 165° C. to form a ripened material with stable performance. In this step, the ripening temperature in the oven is higher than the traditional working temperature of 150° C.

(14) (5) Cooling step, the ripened material is transferred into a cold roller by the conveying platform at a speed of 3 m/min, and subjected to a pressure roll cooling process at 20° C. to form a latex pad.

(15) (6) Winding step, the surface of formed latex pad is covered with an isolation paper, and the latex pad is wound together with the isolation paper into a coil of latex pad. The isolation paper may be a membrane made of polyethylene (PE).

(16) The coil of latex pad produced by the composition and method according to the present invention may be processed into various kinds of pad body products, such as shoe pads, chest pads, and the like. Because the latex pad is made from the present composition, the pad body products will contain functional additives including nano sliver, nano zinc oxide and active carbon, in addition to the latex materials of natural latex and artificial latex. Therefore, the pad body products will exhibit good mechanical properties of soft resilience, extensibility, ductility resistance and tear resistance, and also possess characterized properties of high cleanliness, temperature resistance, aging resistance, wear resistance, and functional efficacy of bacterial killing, temperature lowering, warming, improved moisture absorption, deodorization, mildew proofing, microbial inhibiting and ventilating. It is noticed that the moisture absorption, deodorization, mildew proofing, microbial inhibiting and ventilating efficacies of the latex pad products will be relatively improved because the proportion of active carbon added in the latex pad is increased from 2% to 5% by weight.