Method for concentrating rubber emulsion and product thereof

Abstract

A method for concentrating rubber emulsion and a product prepared by the method are provided, the method includes: a concentrated latex is obtained by separating a superabsorbent resin added in advance into a rubber emulsion with a solid content of 0.01-70% after stirring and concentrating the resin-added rubber emulsion. The method requires simple equipment and consumes less energy, and the prepared polymer emulsion has a solid content up to 76%; the superabsorbent resin adopted herein is reusable after drying, which therefore effectively reduces the production cost; natural latex concentrated by the method has rather high yields of dry rubber and little wastewater production; products prepared from the concentrated natural latex have excellent mechanical property, aging resistance and adhesive property; and concentrating natural latex according to this method does not require advance agglomeration, which reduces the production procedures and improves the production efficiency significantly.

Claims

1. A method for concentrating rubber emulsion, comprising: adding a superabsorbent resin into a rubber emulsion with a solid content of 0.01-70% to obtain a resin-added rubber emulsion, and stirring the resin-added rubber emulsion for concentrating; and obtaining a concentrated latex by separating the superabsorbent resin from the resin-added rubber emulsion after the concentrating; wherein the superabsorbent resin comprises a sodium polyacrylate superabsorbent resin.

2. The method for concentrating rubber emulsion according to claim 1, wherein the rubber emulsion comprises one selected from the group consisting of a natural latex, a concentrated natural latex, a pre-vulcanized natural latex, an epoxidized natural latex, a deproteinized natural latex, a skim latex, a styrene-butadiene latex, a carboxylated styrene-butadiene latex, an acrylonitrile-butadiene latex, a neoprene latex, a butyl emulsion, a polyisoprene latex, and mixtures thereof; or the rubber emulsion comprises a waste latex produced by an acid, one of an inorganic salt and a polymer flocculant, and a bio-coagulated emulsion.

3. The method for concentrating rubber emulsion according to claim 1, wherein a mass fraction of the superabsorbent resin in the resin-added rubber emulsion is in a range from 0.1% to 10%.

4. The method for concentrating rubber emulsion according to claim 1, wherein the superabsorbent resin is a granular resin with a diameter in a range from 50 micrometers (μm) to 0.5 centimeters (cm).

5. The method for concentrating rubber emulsion according to claim 1, wherein a stirring speed of the stirring is in a range from 200 radians per minute (r/min) to 500 r/min.

6. The method for concentrating rubber emulsion according to claim 1, wherein the concentrating is a concentrating in a step-by-step manner or a concentrating in a one-step manner, and a duration for each step of concentrating is in a range from 4 hours (h) to 8 h.

7. The method for concentrating rubber emulsion according to claim 1, wherein the separating is carried out by filtration or centrifugation.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

(1) Various exemplary embodiments of the disclosure are now described in detail, which should not be considered a limitation of the disclosure, but rather as a more detailed description of certain aspects, features and embodiments of the disclosure.

(2) It should be understood that the terms used in this disclosure are only for describing specific embodiments, and are not used to limit the disclosure. In addition, for the numerical range in the disclosure, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Any stated value or intermediate value within the stated range and any other stated value or every smaller range between intermediate values within the stated range are also included in the disclosure. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

(3) Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by the ordinary technicians in the field of this disclosure. Although the disclosure only describes the preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the disclosure. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and/or materials related to the documents. In case of conflict with any incorporated documents, the contents of this specification shall prevail.

(4) Without departing from the scope or spirit of the disclosure, it is obvious to those skilled in the art that many modifications and changes can be made to the specific embodiments of the disclosure. Other embodiments obtained from the description of the disclosure will be obvious to those skilled in the art. The specification and embodiments of this application are exemplary only.

(5) The words “including”, “comprising”, “having” and “containing” used in this application are all open terms, that is, they mean including but not limited to.

First Embodiment

(6) A method for concentrating rubber emulsion includes the following specific steps:

(7) adding superabsorbent resin (for example, sodium polyacrylate) into fresh natural latex with a solid content of 31% at a stirring speed of 250 r/min, the mass fraction of sodium polyacrylate in rubber emulsion is 3%; performing stirring for 8 hours, then filtering to remove the superabsorbent resin to prepare concentrated natural latex with a solid content of 63% (dry rubber content of 60.1%).

Second Embodiment

(8) A method for concentrating rubber emulsion includes the following specific steps:

(9) adding superabsorbent resin (for example, sodium polyacrylate) into fresh natural latex with a solid content of 31% at a stirring speed of 250 r/min, the mass fraction of sodium polyacrylate in rubber emulsion is 3%; performing stirring for 8 hours, and then filtering to remove the superabsorbent resin to prepare concentrated natural latex with a solid content of 63%; at the stirring speed of 250 r/min, again adding superabsorbent resin (sodium polyacrylate) into that prepared concentrated natural latex until the mass fraction in the rubber emulsion is 2.4%, performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare concentrated natural latex with a solid content of 69%; again under same stirring speed of 250 r/min, adding superabsorbent resin (sodium polyacrylate) for the third time into the concentrated natural latex prepared after the second filtration until the mass fraction in the rubber emulsion is 1.9%, performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare concentrated natural latex with a solid content of 75%; finally a concentrated natural latex with high solid content of 75% is obtained after three times of step-by-step concentration.

Third Embodiment

(10) A new method for concentrating rubber emulsion includes the following specific steps:

(11) adding superabsorbent resin (for example, sodium polyacrylate) into skim latex with a solid content of 8.85% (dry rubber content of 4.89%) at a stirring speed of 300 r/min, the mass fraction of sodium polyacrylate is 3%, performing stirring for 6 hours, then filtering to remove the superabsorbent resin to prepare concentrated skim latex with a solid content of 24.8% (dry rubber content of 21.75%).

Fourth Embodiment

(12) A method for concentrating rubber emulsion includes the following specific steps:

(13) adding superabsorbent resin (for example, sodium polyacrylate) into epoxidized natural latex with a solid content of 32% at a stirring speed of 300 r/min, the mass fraction of sodium polyacrylate in rubber emulsion is 3%; performing stirring for 8 hours, then filtering to remove the superabsorbent resin to prepare concentrated natural latex with a solid content of 37%; again adding superabsorbent resin (sodium polyacrylate) with mass fraction of 2.4% into that concentrated natural latex prepared after that previous filtering at a stirring speed of 250 r/min, performing stirring for 8 hours, then filtering to remove the superabsorbent resin to prepare concentrated epoxidized natural latex with a solid content of 42%; since a large number of surfactants affecting the concentration effect are introduced during the preparation of epoxidized natural latex, the solid content of the resulting concentrated epoxidized natural latex is rather low under the same experimental conditions.

Fifth Embodiment

(14) A method for concentrating rubber emulsion includes the following specific steps:

(15) adding superabsorbent resin (for example, sodium polyacrylate) into deproteinized natural latex with a solid content of 40% at a stirring speed of 300 r/min, the mass fraction of sodium polyacrylate in rubber emulsion is 3%, performing stirring for 8 hours, and then filtering to remove the superabsorbent resin to prepare concentrated deproteinized natural latex with a solid content of 46%; again adding superabsorbent resin (sodium polyacrylate) with mass fraction of 2.4% into that concentrated deproteinized natural latex prepared after that previous filtering at a stirring speed of 250 r/min, and performing stirring for 8 hours, then filtering to remove the superabsorbent resin to prepare concentrated deproteinized natural latex with a solid content of 52%; since a large number of surfactants affecting the concentration effect are introduced during the preparation of deproteinized natural latex, the solid content of the resulting concentrated deproteinized natural latex is rather low under the same experimental conditions.

Sixth Embodiment

(16) A method for concentrating rubber emulsion includes the following specific steps:

(17) adding superabsorbent resin (for example, sodium polyacrylate) into styrene-butadiene latex with a solid content of 28% at a stirring speed of 300 r/min, the mass fraction of sodium polyacrylate in rubber emulsion is 3.5%, performing stirring for 8 hours, and then filtering to remove the superabsorbent resin to prepare styrene-butadiene latex with a solid content of 50%; again adding superabsorbent resin (sodium polyacrylate) with mass fraction of 2.4% into that styrene-butadiene latex prepared after that previous filtering, performing stirring for 7 hours, and then filtering to remove the superabsorbent resin to prepare concentrated styrene-butadiene latex with a solid content of 63%.

Seventh Embodiment

(18) A method for concentrating rubber emulsion includes the following specific steps:

(19) adding superabsorbent resin (for example, sodium polyacrylate) into carboxylated styrene-butadiene latex with a solid content of 50% at a stirring speed of 300 r/min, the mass fraction of sodium polyacrylate in rubber emulsion is 3%, performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare carboxylated styrene-butadiene latex with a solid content of 58%; again adding superabsorbent resin (sodium polyacrylate) into that carboxylated styrene-butadiene latex prepared after that previous filtering, the mass fraction of sodium polyacrylate in carboxylated styrene-butadiene latex is 2.4%, performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare concentrated carboxylated styrene-butadiene latex with a solid content of 63%; adding superabsorbent resin (sodium polyacrylate) for the third time into that concentrated carboxylated styrene-butadiene latex prepared after second filtering, the mass fraction of sodium polyacrylate in rubber emulsion is 1.9%; performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare concentrated carboxylated styrene-butadiene latex; finally a concentrated carboxylated styrene-butadiene latex with high solid content of 67% is obtained after three times of step-by-step concentration.

Eighth Embodiment

(20) A method for concentrating rubber emulsion includes that following specific steps:

(21) adding superabsorbent resin (for example, sodium polyacrylate) into neoprene latex with a solid content of 50% at a stirring speed of 300 r/min, the mass fraction of sodium polyacrylate in rubber emulsion is 3%, performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare neoprene latex with a solid content of 57%; again adding superabsorbent resin (sodium polyacrylate) into that neoprene latex prepared after that previous filtering, the mass fraction of sodium polyacrylate in neoprene latex is 2.4%, performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare concentrated neoprene latex with a solid content of 62%; adding superabsorbent resin (sodium polyacrylate) for the third time into that concentrated neoprene latex prepared after second filtering, the mass fraction of sodium polyacrylate in rubber emulsion is 1.9%, performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare concentrated neoprene latex; finally a concentrated neoprene latex with high solid content of 66% is obtained after three times of step-by-step concentration.

Ninth Embodiment

(22) A method for concentrating rubber emulsion includes the following specific steps:

(23) adding superabsorbent resin (for example, sodium polyacrylate) into acrylonitrile-butadiene latex with a solid content of 44% at a stirring speed of 300 r/min, the mass fraction of sodium polyacrylate in rubber emulsion is 3%, performing stirring for 6 hours, then filtering to remove the superabsorbent resin to prepare acrylonitrile-butadiene latex with a solid content of 54%; again adding superabsorbent resin (sodium polyacrylate) into that acrylonitrile-butadiene latex prepared after that previous filtering, the mass fraction of sodium polyacrylate in acrylonitrile-butadiene latex is 2.4%, performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare concentrated acrylonitrile-butadiene latex with a solid content of 61%; adding superabsorbent resin (sodium polyacrylate) for the third time into that concentrated acrylonitrile-butadiene latex prepared after second filtering, the mass fraction of sodium polyacrylate in rubber emulsion is 1.9%, performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare concentrated acrylonitrile-butadiene latex; finally a concentrated acrylonitrile-butadiene latex with high solid content of 67% is obtained after three times of step-by-step concentration.

Tenth Embodiment

(24) A method for concentrating rubber emulsion includes the following specific steps:

(25) adding superabsorbent resin (for example, sodium polyacrylate) into polyisoprene latex with a solid content of 50% at a stirring speed of 300 r/min, the mass fraction of sodium polyacrylate in rubber emulsion is 3%, performing stirring for 6 hours, then filtering to remove the superabsorbent resin to prepare polyisoprene latex with a solid content of 60%; again adding superabsorbent resin (sodium polyacrylate) into that polyisoprene latex prepared after that previous filtering, the mass fraction of sodium polyacrylate in polyisoprene latex is 2.4%, performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare concentrated polyisoprene latex with a solid content of 68%; adding superabsorbent resin (sodium polyacrylate) for the third time into that concentrated polyisoprene latex prepared after second filtering, the mass fraction of sodium polyacrylate in rubber emulsion is 1.9%, performing stirring for 6 hours, and then filtering to remove the superabsorbent resin to prepare concentrated polyisoprene latex; finally a concentrated polyisoprene latex with high solid content of 76% is obtained after three times of step-by-step concentration.

Eleventh Embodiment

(26) A concentration method of rubber emulsion, the specific steps are the same as those in the first embodiment, except for the specific parameters and experimental results in Table 1.

(27) TABLE-US-00001 TABLE 1 Effect of the amount of superabsorbent resin on adsorption effect Latex Solid coated Rubber super- content of with Stirring emulsion/ absorbent concen- super- speed solid resin/mass Stirring trated absorbent S/N (r/min) content fraction duration latex resin 1 250 Natural Sodium 2.5 h 63% Many latex/31% polyacrylate/ 10% 2 250 Natural Sodium   4 h 63% Many latex/31% polyacrylate/ 8% 3 250 Natural Sodium   6 h 63% Not latex/31% polyacrylate/ much 5% 4 250 Natural Sodium   8 h 63% None latex/31% polyacrylate/ 3% 5 250 Natural Sodium  16 h 63% None latex/31% polyacrylate/ 1% 6 250 Natural Sodium  48 h 63% None latex/31% polyacrylate/ 0.1%

(28) As concluded from the data in Table 1, for reaching the same solid content, duration for concentration is decreased progressively as the amount of superabsorbent resin (sodium polyacrylate) is increased; however, as the amount of resin is increased, the situation of superabsorbent resin being coated by latex gradually becomes serious. The wrapping of latex by superabsorbent resin (none, not much, many) is used to exemplify the amount of latex loss, whether it is easy to separate, and whether it is easy to recycle; specifically, the more latex coated with superabsorbent resin, the greater the loss; the larger the amount of wrapping, the difficult to separate the superabsorbent resin and the less conducive to recycling. Considering the time cost, latex loss and recycling situation, it is determined that the dosage of sodium polyacrylate is 3%.

Twelfth Embodiment

(29) A method for concentrating rubber emulsion, which is the same as that in the first embodiment, except for the parameters and the experimental results shown in Table 2.

(30) TABLE-US-00002 TABLE 2 Influence of different kinds of superabsorbent resin on adsorption effect Type/mass Rubber Solid fraction of Stirring emulsion/ content of superabsorbent speed solid Stirring concentrated S/N resin r/min content duration latex 1 Sodium polyacrylate 250 Natural  3 h 63% resin/3% latex/31% 2 Polyvinyl alcohol 250 Natural 10 h 63% resin/3% latex/31% 3 Polyoxyethylene 250 Natural  9 h 63% resin/3% latex/31% 4 Starch resin/3% 250 Natural 12 h 63% latex/31% 5 Acrylonitrile 250 Natural 11 h 63% cellulose resin/3% latex/31%

(31) The data in Table 2 shows that under the same experimental conditions, the duration required to concentrate the latex to the same solid content is the shortest when the superabsorbent resin is sodium polyacrylate.

Thirteenth Embodiment

(32) A method for concentrating rubber emulsion, which is the same as that in the second embodiment, except for the parameters and the experimental results shown in Table 3.

(33) TABLE-US-00003 TABLE 3 Adsorption effect of different amount of superabsorbent resin on step by step concentration super- super- super- Latex absorbent absorbent absorbent Solid coated resin resin resin content with Rubber in 1.sup.st in 2.sup.st in 3.sup.st of super- emulsion/ adsorption/ adsorption/ adsorption/ concen- absorb- solid mass mass mass trated ent S/N content fraction fraction fraction latex resin 1 Natural 3%   3%   3% 75% Not latex/31% much 2 Natural 3%   5%  10% 75% Many latex/31% 3 Natural 3% 2.4% 1.9% 75% None latex/31%

(34) It can be concluded from the data in Table 3 that in the process of step-by-step concentration, it is not easy for the superabsorbent resin to be wrapped by the latex if the amount of superabsorbent resin is gradually reduced, which is not only beneficial to the separation of resin from the latex and reducing the loss of latex, but also ensures the recycling of superabsorbent resin.

(35) What has been described above are only the preferred embodiments of the disclosure, and it is not intended to limit the disclosure. Any modification, equivalent replacement and improvement within the spirit and principle of the disclosure should be included in the scope of protection of the disclosure.