1. A method for preparing natural low-protein concentrated latex is characterized in that: the method comprises the following steps:

s1, preparing a creaming agent: the creaming agent comprises the following raw materials in parts by weight: 2-9 parts of potassium alginate, 1-5 parts of sodium metasilicate, 3-8 parts of sodium oleate and 0.2-0.9 part of potassium hydroxide;

s2, primary separation: preparing the dry content of fresh latex to be 26-27%, adding a creaming agent and TT/ZnO into the fresh latex, adjusting the ammonia content to be 0.3-0.5%, stirring, standing for 18-27 h, gathering and floating latex particles, separating whey from whey, and removing whey to obtain creamed fresh latex I;

s3, secondary separation: supplementing water and a creaming agent into the creamed fresh latex I obtained in the step S2, standing for 18-27 h, separating the latex particles from whey by aggregation and floating, and removing the whey to obtain creamed fresh latex II;

s4, three times of separation: and adding water into the creamed fresh latex II obtained in the step S3, and centrifuging to obtain the low-protein concentrated milk.

2. The method of claim 1, wherein the natural low protein concentrated latex is prepared by: the creaming agent comprises the following raw materials in parts by weight: 5 parts of potassium alginate, 3 parts of sodium metasilicate, 5 parts of sodium oleate and 0.6 part of potassium hydroxide.

3. The method of claim 1, wherein the natural low protein concentrated latex is prepared by: the addition amount of the creaming agent in the S2 is 0.15-0.20% of the volume of the fresh latex.

4. The method of claim 1, wherein the natural low protein concentrated latex is prepared by: the addition amount of TT/ZnO in the S2 is 0.12-0.18% of the volume of the fresh latex.

5. The method of claim 1, wherein the natural low protein concentrated latex is prepared by: the amount of water added in S3 was the same as the volume of the virgin latex I.

6. The method of claim 1, wherein the natural low protein concentrated latex is prepared by: the supplementary amount of the creaming agent in the S3 is 0.12-0.18% of the volume of the fresh latex I.

7. The method of claim 1, wherein the natural low protein concentrated latex is prepared by: the amount of water added to the S4 was the same as the volume of the fresh latex II.

Background

The natural latex is a biosynthetic high polymer water-based colloid system, which mainly comprises rubber hydrocarbon, water and non-colloid substances, wherein the non-colloid substances mainly comprise protein (most), lipoid, acetone soluble substances, water soluble substances, inorganic salt and the like. Nowadays, the demand of natural latex products, particularly natural latex gloves and condoms, is rapidly rising due to the increased consciousness of people for preventing viral infections, but people soon find that the use of natural latex products causes anaphylaxis, the first symptom is urticaria, then skin itch, pimple and other symptoms are generated, and anaphylactic shock and even death are caused in severe cases. The main reason for this is allergy caused by proteins contained in natural latex itself. Further research shows that the total residual amount of soluble protein in natural latex is in positive correlation with the frequency and severity of anaphylaxis. Therefore, the development of low-protein natural latex which is stable and non-allergic to human body is a popular research in the latex industry today.

The patent "a low protein content medical natural rubber material and its preparation method", patent no: CN102329442B, it is an indiscriminate deproteinization technique to use protease to remove protein in latex, and the protein in the protective layer of latex particles can also be removed, causing the destruction of latex particles and resulting in the decrease of latex stability. Most of latex is deproteinized by protease, and when the protease is used for deproteinizing, in order to prevent the latex particle protective layer from being damaged after the protein in the latex particle protective layer is removed, so that the stability of the latex is reduced, a large amount of surface stabilizer needs to be added to protect the latex particles from the condition of latex solidification. However, the large amount of the stabilizer has the adverse effect of difficult forming of downstream products, and is not beneficial to the production of the downstream products.

Disclosure of Invention

Accordingly, the present invention is directed to a method for preparing a natural low protein latex concentrate to solve the above problems.

The technical scheme of the invention is realized as follows: a method for preparing natural low-protein concentrated latex comprises the following steps:

s1, preparing a creaming agent: the creaming agent comprises the following raw materials in parts by weight: 2-9 parts of potassium alginate, 1-5 parts of sodium metasilicate, 3-8 parts of sodium oleate, 0.2-0.9 part of potassium hydroxide,

S2, primary separation: preparing the dry content of fresh latex to be 26-27%, adding a creaming agent and TT/ZnO into the fresh latex, adjusting the ammonia content to be 0.3-0.5%, stirring, standing for 18-27 h, gathering and floating latex particles, separating whey from whey, and removing whey to obtain creamed fresh latex I;

s3, secondary separation: supplementing water and a creaming agent into the creamed fresh latex I obtained in the step S2, standing for 18-27 h, separating the latex particles from whey by aggregation and floating, and removing the whey to obtain creamed fresh latex II;

s4, three times of separation: and adding water into the creamed fresh latex II obtained in the step S3, and centrifuging to obtain the low-protein concentrated milk.

Further, the creaming agent comprises the following raw materials in parts by weight: 5 parts of potassium alginate, 3 parts of sodium metasilicate, 5 parts of sodium oleate and 0.6 part of potassium hydroxide.

Furthermore, the addition amount of the creaming agent in the S2 is 0.15-0.20% of the volume of the fresh latex.

Furthermore, the addition amount of TT/ZnO in the S2 is 0.12-0.18% of the volume of the fresh latex.

Further, the amount of water added in S3 is equal to the volume of the field latex I.

Furthermore, the addition amount of the creaming agent in the S3 is 0.12-0.18% of the volume of the fresh latex I.

Further, the amount of water added in S4 is equal to the volume of the field latex ii.

Compared with the prior art, the invention has the beneficial effects that:

the invention abandons the traditional protease deproteinization technology and adopts a method of creaming and aggregating latex particles and separating whey protein;

(2) simple process operation and can realize industrialized production

The invention only needs to add the raw materials of the creaming agent, the ammonia water and the like into the fresh latex, scientifically match, stir and stand;

(3) selective protein removal

When the protein in the latex is removed, only the protein dissolved in the whey is removed, but the protein in the protective layer of the latex particles is not removed, so that the latex particles are not damaged;

(4) without the need to add large amounts of stabilizers

The low-protein concentrated latex does not contain a large amount of stabilizer so as to ensure the production of downstream latex products.

Drawings

FIG. 1 is a technical route of natural low protein concentrated latex

Detailed Description

In order to better understand the technical content of the invention, specific examples are provided below to further illustrate the invention.

The experimental methods used in the examples of the present invention are all conventional methods unless otherwise specified.

The materials, reagents and the like used in the examples of the present invention can be obtained commercially without specific description.

Example 1

A method for preparing natural low-protein concentrated latex comprises the following steps:

s1, preparing a creaming agent: the creaming agent comprises the following raw materials in parts by weight: 2 parts of potassium alginate, 1 part of sodium metasilicate, 3 parts of sodium oleate, 0.2 part of potassium hydroxide,

S2, primary separation: preparing the dry content of fresh latex to be 26%, adding a creaming agent accounting for 0.15% of the volume of the fresh latex, adding TT/ZnO accounting for 0.12% of the volume of the fresh latex into the fresh latex, adjusting the ammonia content to be 0.3%, stirring, standing for 18h, aggregating and floating latex particles, separating whey, and removing whey to obtain creamed fresh latex I;

s3, secondary separation: supplementing the creamed fresh latex I obtained in the step S2 with water with the same volume as that of the creaming agent with the volume of 0.12% of that of the fresh latex I, standing for 18 hours, collecting and floating latex particles, separating whey, and removing whey to obtain creamed fresh latex II;

s4, three times of separation: and adding equal volume of water into the creamed fresh latex II obtained in the step S3, and centrifuging to obtain the low-protein concentrated milk.

Example 2

S1, preparing a creaming agent: the creaming agent comprises the following raw materials in parts by weight: 9 portions of potassium alginate, 5 portions of sodium metasilicate, 8 portions of sodium oleate, 0.9 portion of potassium hydroxide,

S2, primary separation: preparing 27% of dry content of fresh latex, adding a creaming agent accounting for 0.20% of the volume of the fresh latex, adding TT/ZnO accounting for 0.18% of the volume of the fresh latex into the fresh latex, adjusting the ammonia content to be 0.5%, stirring, standing for 27h, aggregating and floating latex particles, separating whey, and removing whey to obtain creamed fresh latex I;

s3, secondary separation: supplementing the creamed fresh latex I obtained in the step S2 with water with the same volume as that of the creaming agent with the volume of 0.18% of that of the fresh latex I, standing for 27 hours, separating the latex particles from whey by aggregation and floating, and removing the whey to obtain creamed fresh latex II;

s4, three times of separation: and adding equal volume of water into the creamed fresh latex II obtained in the step S3, and centrifuging to obtain the low-protein concentrated milk.

Example 3

S1, preparing a creaming agent: the creaming agent comprises the following raw materials in parts by weight: 5 parts of potassium alginate, 3 parts of sodium metasilicate, 5 parts of sodium oleate and 0.6 part of potassium hydroxide;

s2, primary separation: preparing the dried content of fresh latex to be 26.5%, adding a creaming agent accounting for 0.17% of the volume of the fresh latex, adding TT/ZnO accounting for 0.15% of the volume of the fresh latex into the fresh latex, adjusting the ammonia content to be 0.4%, stirring, standing for 24 hours, aggregating and floating latex particles, separating whey, and removing whey to obtain creamed fresh latex I;

s3, secondary separation: supplementing the creamed fresh latex I obtained in the step S2 with water with the same volume as that of the creaming agent with the volume of 0.15% of that of the fresh latex I, standing for 24 hours, separating the latex particles from whey by aggregation and floating, and removing the whey to obtain creamed fresh latex II;

s4, three times of separation: and adding equal volume of water into the creamed fresh latex II obtained in the step S3, and centrifuging to obtain the low-protein concentrated milk.

Comparative example 1

The difference between the comparative example and the example 3 is that the creaming agent comprises the following raw materials in parts by weight: 1 part of potassium alginate, 6 parts of sodium metasilicate, 2 parts of sodium oleate and 0.1 part of potassium hydroxide.

Comparative example 2

The difference between the comparative example and the example 3 is that the creaming agent comprises the following raw materials in parts by weight: 10 parts of potassium alginate, 6 parts of sodium metasilicate, 9 parts of sodium oleate and 0.1 part of potassium hydroxide.

Detecting data

Data statistics of nitrogen content detection were performed by processing the fresh latex according to the methods of examples 1 to 3 and comparative examples 1 to 2. Also, the data for the partial detection of the treated low protein latex concentrate of the invention was compared to the data for the partial detection of the high ammonia latex concentrate. The goal is to better understand the properties of the low protein concentrated latex.

Table 1 shows the data of the nitrogen content of the processed fresh latex

The invention adopts a specific method, the latex particles are creamed and aggregated, whey protein is separated, protein in fresh latex is effectively removed, the formula of the creaming agent is mainly adopted for stirring and standing, the creaming agent raw materials are reasonably selected, the proportioning is scientific, the synergy is realized, and a better denitrification effect is achieved.

Total solid, dry content, dry difference, ammonia content, volatile acid, organic stability and nitrogen content were measured for the low protein concentrated latexes of examples 1 to 3 and comparative examples 1 to 2, and Table 2 shows the data of the low protein concentrated latex:

table 2:

as can be seen from the above table, the concentrated milk prepared by the invention has low protein content, selectively removes protein, and achieves better low-protein concentrated latex, compared with the conventional high-ammonia concentrated milk, the total solid content and the dry content of the concentrated milk prepared by the invention reach the standard, and the dry difference value is 7-8 times lower than that of the conventional high-ammonia concentrated milk, because most non-glue substances are removed while the whey protein is removed, and the low dry difference value can reduce the hygroscopicity and the conductivity of a latex product, is beneficial to manufacturing an insulating product, is beneficial to producing a transparent latex product, and can also eliminate the odor; the volatile acid value is 4-5 times lower than that of the conventional high-ammonia concentrated milk, and the low volatile value is beneficial to better storage of the low-protein concentrated milk and the stability of the subsequent product production; the nitrogen content of the invention is lower than 0.15%, the low nitrogen content can reduce the water absorption, the moisture absorption, the conductivity and the heat generation of the latex product, the latex product is not easy to mildew, and the invention is beneficial to producing the anti-protein allergy latex product and producing the insulating latex product.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.