CN113736156A

CN113736156A - Epoxidized natural latex sponge and preparation method and application thereof

Info

Publication number: CN113736156A
Application number: CN202111221996.5A
Authority: CN
Inventors: 罗梓蓉; 陶金龙; 孔娜; 张吉振; 李志锋; 赵鹏飞; 丁宏达
Original assignee: Agricultural Products Processing Research Institute of CATAS
Current assignee: Agricultural Products Processing Research Institute of CATAS
Priority date: 2021-10-20
Filing date: 2021-10-20
Publication date: 2021-12-03
Anticipated expiration: 2041-10-20
Also published as: CN113736156B

Abstract

The invention discloses an epoxidized natural latex sponge and a preparation method and application thereof, and belongs to the technical field of sponge preparation. The epoxidized natural latex sponge comprises the following raw materials in parts by weight: the epoxidized natural latex sponge is prepared by a mechanical foaming method, has excellent porous structure and mechanical property, has slow rebound resilience (relatively slow rebound speed), can memorize the shape of an object and effectively disperse pressure, and is expected to be applied to the fields of household goods, medical rehabilitation and cushioning packaging.

Description

Epoxidized natural latex sponge and preparation method and application thereof

Technical Field

The invention relates to an epoxidized natural latex sponge and a preparation method and application thereof, belonging to the technical field of sponge preparation.

Background

The sponge is a porous open type material with low density, and is widely applied to the aspects of industrial production and life and the like due to the advantages of good air permeability, heat preservation, sound insulation, heat insulation, shock absorption, flame retardance, compression fatigue resistance and the like. At present, the sponge is mostly prepared by using natural latex which is an important engineering material with excellent comprehensive performance, but the sponge prepared by using the natural rubber has certain defects in mechanical property because the sponge is a nonpolar natural polymer material and has poor special properties such as heat resistance, oil resistance, air tightness, adhesiveness and the like.

In order to obtain more excellent properties such as heat resistance, oil resistance, air impermeability and adhesiveness, epoxidized natural rubber is generally produced by a chemical modification method, but the epoxidized natural rubber after modification has a polarity problem and it is difficult to obtain concentrated latex with a high concentration, so that it is rare to directly produce a sponge using epoxidized natural latex. In the prior art, epoxidized natural latex sponge is prepared by a chemical foaming method, but gas generated by foaming can cause the structural permeability coefficient of rubber to be large, closed-cell foamed rubber is difficult to prepare, the prepared foamed rubber has low quality, low strength and large shrinkage rate and is easy to deform, and in addition, residual foaming agent after foaming can generate certain influence on the performance of the sponge, which seriously hinders the development of the epoxidized natural latex sponge.

Therefore, if a method for preparing high-performance sponge by using epoxidized natural latex can be provided, it is of great significance to widen the application of the epoxidized natural latex.

Disclosure of Invention

In order to solve the technical problems, the invention provides an epoxidized natural latex sponge and a preparation method and application thereof, and the sponge with excellent structure and mechanical properties is prepared while the application field of epoxidized natural latex is widened.

In order to achieve the purpose, the invention provides the following scheme:

the invention provides an epoxidized natural latex sponge which comprises the following raw materials in parts by weight: 100 parts of epoxidized natural latex, 2-3 parts of vulcanizing agent, 1-3 parts of accelerator, 0.75 part of anti-aging agent, 1-2 parts of foaming agent, 1.5-3 parts of vulcanizing activator, 1 part of stabilizer and 0.5-1 part of gelling agent.

Further, the epoxidized natural latex is concentrated emulsion, the total solid content of the latex is more than 60%, and the epoxidation degree is 50 mol%.

Further, the vulcanizing agent is sulfur, the accelerators are zinc diethyldithiocarbamate (accelerator ZDC) and 2-mercaptobenzothiazole (accelerator M), the anti-aging agent is 2-mercaptobenzimidazole (anti-aging agent MB), the vulcanization activator is zinc oxide, the foaming agent is potassium oleate, the stabilizer is potassium hydroxide, and the gelling agent is sodium fluosilicate.

Further, the mass ratio of zinc diethyldithiocarbamate (accelerator ZDC) to 2-mercaptobenzothiazole (accelerator M) in the accelerator is 5: 3.

The invention also provides a preparation method of the epoxidized natural latex sponge, which comprises the following steps:

weighing the raw materials in parts by weight, dispersing the vulcanizing agent, the accelerator, the anti-aging agent and the stabilizer in water to obtain a dispersion, adding the dispersion into epoxidized natural latex, uniformly stirring, curing, adding a foaming agent, stirring and foaming, adding a vulcanization activator after uniform foaming, adding a gelling agent after stirring for gelling, shaping and vulcanizing, and dehydrating, washing and drying to obtain the epoxidized natural latex sponge.

Further, the total solid content of the dispersion was 50%, the mass concentration of the foaming agent was 20%, and the mass concentration of the vulcanization activator and the gelling agent was 50%.

Further, the stirring temperature of the dispersion added into the epoxidized natural latex is 25-35 ℃, the stirring time is 1 hour, the curing time is 24-48 hours, the stirring speed of the added foaming agent is 600-1200 rpm, and the uniform foaming is carried out at 200-400 rpm.

Further, the setting temperature is 90-100 ℃, the setting time is 10-15 min, the vulcanization temperature is 90-110 ℃, and the vulcanization time is 30-45 min.

Further, the drying is hot air drying, the temperature is 60-70 ℃, and the time is 3-5 hours.

The invention also provides application of the epoxidized natural latex sponge in household articles, medical rehabilitation and cushioning packaging.

The invention discloses the following technical effects:

(1) the latex sponge is prepared by using epoxidized natural latex as a main raw material, partial carbon-carbon double bonds of natural rubber are converted into epoxy bonds through epoxidation reaction to obtain chemically modified natural latex, so that the epoxidized natural latex still keeps the original molecular configuration of the natural latex and has some basic properties of the natural rubber, meanwhile, a part of nonpolar carbon-carbon double bonds are converted into polar epoxy bonds, and concentrated latex with high concentration and high solid content is formed by a method that a high water absorption resin and water molecules in rubber emulsion are hydrated to absorb a large amount of water, so that the epoxidized natural latex becomes polar rubber and shows excellent oil resistance, gas barrier property, adhesion property and the like.

(2) The sponge prepared by the high-concentration epoxidized latex through the mechanical foaming method overcomes the defects that the closed-cell foamed latex is difficult to prepare by the chemical foaming method, and the prepared foamed latex has low quality, low strength, easy deformation and the like. The epoxidized natural latex sponge prepared by the method has excellent porous structure and mechanical property, has slow rebound resilience, namely relatively slow rebound speed, can remember the shape of an object, effectively disperse pressure, and is expected to be applied to the fields of household articles, medical rehabilitation and buffer packaging.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 is an SEM image of an epoxidized natural latex sponge prepared in example 1;

FIG. 2 is an SEM image of an epoxidized natural latex sponge prepared in example 2;

FIG. 3 is an SEM image of an epoxidized natural latex sponge prepared in example 3;

FIG. 4 is an SEM image of an epoxidized natural latex sponge prepared in example 4;

FIG. 5 is an SEM image of an epoxidized natural latex sponge prepared in example 5;

FIG. 6 is an SEM image of an epoxidized natural latex sponge prepared in comparative example 1;

FIG. 7 is an SEM image of an epoxidized natural latex sponge prepared in comparative example 2;

FIG. 8 is an SEM image of an epoxidized natural latex sponge prepared in comparative example 3.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.

The technical solution of the present invention is further illustrated by the following examples.

The epoxidized natural latex concentrated emulsion is prepared according to the method in Chinese patent CN 202110577238: a concentrated latex with a solid content of 60% is obtained by adding a super absorbent resin to an epoxidized natural rubber emulsion with a solid content of 30%, stirring and concentrating, and then separating the super absorbent resin.

Example 1

Weighing 100 parts by mass of epoxidized natural latex concentrated emulsion with the total solid content of 60% and the epoxidation degree of 50 mol%, adding a dispersion with the total solid content of 50% prepared from 2 parts of sulfur, 1 part of accelerator ZDC, 0.6 part of accelerator M, 0.75 part of antioxidant MB and 1 part of potassium hydroxide, mixing and stirring for 1 hour at 30 ℃, standing and curing for 24 hours after uniformly stirring. After completion of the aging, 1.5 parts by mass of a 20% potassium oleate solution was added, and the mixture was stirred and foamed at 1000rpm for 15 minutes. And then homogenizing at the stirring speed of 300rpm, adding 2 parts of zinc oxide with the mass concentration of 50%, continuing to stir after 2min, adding 0.9 part of sodium fluosilicate with the mass concentration of 50%, and injecting a film after 30s reaches a gel point. Hot air setting at 90 deg.c for 10min, sulfurizing at 100 deg.c for 45min, demolding, washing three times and hot air drying at 60 deg.c for 3 hr to obtain epoxidized natural latex sponge. The SEM image of the epoxidized natural latex sponge prepared in this example is shown in FIG. 1.

Example 2

Weighing 100 parts by mass of epoxidized natural latex concentrated emulsion with total solid mass of 60% and epoxidation degree of 50 mol%, adding a dispersion with total solid content of 50% prepared by 2 parts of sulfur, 1 part of accelerator ZDC, 0.6 part of accelerator M, 0.75 part of antioxidant MB and 1 part of potassium hydroxide, mixing and stirring for 1 hour at 30 ℃, standing and curing for 24 hours after uniform stirring. After the aging is completed, 2 parts of 20% by mass potassium oleate solution is added, and the mixture is stirred and foamed at a speed of 1200 for 15 min. And then homogenizing at the stirring speed of 200rpm, adding 2 parts of zinc oxide with the mass concentration of 50%, continuing to stir after 2min, adding 0.5 part of sodium fluosilicate with the mass concentration of 50%, and injecting a film after 30s reaches a gel point. Hot air setting at 90 deg.c for 15min, sulfurizing at 100 deg.c for 30min, demolding, washing three times and hot air drying at 60 deg.c for 3 hr to obtain epoxidized natural latex sponge. The SEM image of the epoxidized natural latex sponge prepared in this example is shown in FIG. 2.

Example 3

Weighing 100 parts by mass of epoxidized natural latex concentrated emulsion with total solid mass of 60% and epoxidation degree of 50 mol%, adding a dispersion with total solid content of 50% prepared by 2 parts of sulfur, 1 part of accelerator ZDC, 0.6 part of accelerator M, 0.75 part of antioxidant MB and 1 part of potassium hydroxide, mixing and stirring for 1 hour, standing and curing for 36 hours after uniform stirring. After completion of the aging, 1.5 parts by mass of a 20% potassium oleate solution was added, and the mixture was stirred and foamed at 600rpm for 15 minutes. And then homogenizing at the stirring speed of 200rpm, adding 1.5 parts of zinc oxide with the mass concentration of 50%, continuing stirring after 2min, adding 0.5 part of sodium fluosilicate with the mass concentration of 50%, and injecting a film after 30s reaches a gel point. Hot air setting at 100 deg.c for 15min, sulfurizing at 110 deg.c for 30min, demolding, washing three times and hot air drying at 60 deg.c for 3 hr to obtain epoxidized natural latex sponge. The SEM image of the epoxidized natural latex sponge prepared in this example is shown in FIG. 3.

Example 4

Weighing 100 parts by mass of epoxidized natural latex concentrated emulsion with total solid mass of 60% and epoxidation degree of 50 mol%, adding dispersion with total solid content of 50% prepared by 3 parts of sulfur, 1.875 parts of accelerator ZDC, 1.125 parts of accelerator M, 0.75 part of antioxidant MB and 1 part of potassium hydroxide, mixing and stirring for 1 hour at 35 ℃, standing and curing for 48 hours after uniform stirring. After the completion of the aging, 1 part of a 20% by mass potassium oleate solution was added, and the mixture was stirred and foamed at 1000rpm for 15 minutes. Then, foam homogenizing is carried out at the stirring speed of 300rpm, 3 parts of zinc oxide with the mass concentration of 50% are added, 2min later, 1 part of sodium fluosilicate with the mass concentration of 50% is continuously added, and the film is injected after the gelation point is reached within 30 s. Hot air setting at 100 deg.c for 10min, sulfurizing at 110 deg.c for 45min, demolding, washing three times and hot air drying at 70 deg.c for 5 hr to obtain epoxidized natural latex sponge. The SEM image of the epoxidized natural latex sponge prepared in this example is shown in FIG. 4.

Example 5

Weighing 100 parts by mass of epoxidized natural latex concentrated emulsion with total solid mass of 60% and epoxidation degree of 50 mol%, adding dispersion with total solid content of 50% prepared by 3 parts of sulfur, 0.625 parts of accelerator ZDC, 0.375 parts of accelerator M, 0.75 parts of antioxidant MB and 1 part of potassium hydroxide, mixing and stirring for 1 hour at 35 ℃, standing and curing for 48 hours after uniform stirring. After the completion of the aging, 1 part of a 20% by mass potassium oleate solution was added, and the mixture was stirred and foamed at 1000rpm for 15 minutes. Then, foam homogenizing is carried out at the stirring speed of 300rpm, 3 parts of zinc oxide with the mass concentration of 50% are added, 2min later, 1 part of sodium fluosilicate with the mass concentration of 50% is continuously added, and the film is injected after the gelation point is reached within 30 s. Hot air setting at 100 deg.c for 10min, sulfurizing at 110 deg.c for 45min, demolding, washing three times and hot air drying at 70 deg.c for 3 hr to obtain epoxidized natural latex sponge. The SEM image of the epoxidized natural latex sponge prepared in this example is shown in FIG. 5.

Comparative example 1

The only difference from example 1 is that no accelerator M is added. An SEM image of the epoxidized natural latex sponge prepared in this comparative example is shown in FIG. 6.

Comparative example 2

The only difference from example 1 is that 1.5 parts of a 50% strength by mass potassium oleate solution are added. The SEM image of the epoxidized natural latex sponge prepared in this comparative example is shown in FIG. 7.

Comparative example 3

The only difference from example 1 is that 1.5 parts of antioxidant MB was added. The SEM image of the epoxidized natural latex sponge prepared in this comparative example is shown in FIG. 8.

Comparative example 4

The only difference from example 1 is that after 2 parts of 50% by mass zinc oxide dispersion were added for 15 minutes, 0.9 part of 50% by mass sodium fluorosilicate was added and stirred.

Comparative example 5

The only difference from example 1 is that 2 parts by mass of 50% sodium fluorosilicate were added.

Comparative example 6

The only difference from example 1 is that the aging was carried out for 12 hours.

Comparative example 7

The only difference from example 1 is that the hot air setting was carried out at 110 ℃ for 10min and the vulcanization was carried out at 80 ℃ for 45 min.

Comparative example 8

Weighing 100 parts by mass of epoxidized natural latex concentrated emulsion with the total solid content of 60% and the epoxidation degree of 50 mol%, adding a dispersion with the total solid content of 50% prepared from 2 parts of sulfur, 1 part of accelerator ZDC, 0.6 part of accelerator M, 0.75 part of antioxidant MB, 0.9 part of sodium fluosilicate, 2 parts of zinc oxide and 1 part of potassium hydroxide, mixing and stirring for 1 hour at 30 ℃, standing and curing for 24 hours after uniformly stirring. After the completion of aging, 1.5 parts by mass of a 20% potassium oleate solution was added, and the mixture was stirred and foamed at 1000rpm for 15 minutes. Then, the mixture was homogenized at a stirring speed of 300rpm and film-cast. Hot air setting at 90 deg.c for 10min, vulcanizing at 100 deg.c for 45min, demolding, washing three times and hot air drying at 60 deg.c for 3 hr.

Performance testing

Performance tests were performed on the epoxidized natural latex sponges prepared in examples 1-5 and comparative examples 1-8, and the results of the performance tests are shown in Table 1.

Table 1 results of performance testing

As can be seen from Table 1, the epoxidized natural latex sponges prepared in examples 1 to 5 of the present invention all had a foaming ratio of 5 and an apparent density of 45.72 to 51.43g/cm³The compression set rate is 3.42-5.16%, the tensile strength is 0.28-0.33 MPa, and the elongation at break is 387.55-405.12%, which shows that the material has excellent mechanical properties; the epoxidized natural latex sponges prepared in the embodiments 1 to 5 of the invention have the advantages that the indentation recovery time is 8 to 11 seconds, and the slow rebound effect is good. In the comparative examples 1 to 8, the epoxidized natural latex sponges prepared by changing different conditions in the preparation process have performance degradation in different aspects; in comparative examples 1 to 3, no accelerator M was added to reduce the plasticity and increase the viscosity of the foamed latex, too much potassium oleate, which is a blowing agent, generated a large amount of bubbles in a short time, causing uneven foam coarsening, and when the amount of the antioxidant MB was greater than 1 part, the prepared foamed sponge appeared frosting and turned yellow upon exposure to light; the foamed latex sponges prepared in comparative examples 4-8 all have foam collapse, the compression set is increased by 2.5-4.5 times, the tensile strength is reduced by 51.5-66.7%, the elongation at break is reduced by 39.1-54.4%, and the foamed latex sponges do not have slow rebound characteristics any more.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.

Claims

1. The epoxidized natural latex sponge is characterized by comprising the following raw materials in parts by weight: 100 parts of epoxidized natural latex, 2-3 parts of vulcanizing agent, 1-3 parts of accelerator, 0.75 part of anti-aging agent, 1-2 parts of foaming agent, 1.5-3 parts of vulcanizing activator, 1 part of stabilizer and 0.5-1 part of gelling agent.

2. The epoxidized natural latex sponge according to claim 1, wherein the epoxidized natural latex is a concentrated emulsion having a total latex solids content of greater than 60 percent and an epoxidation level of 50 mole percent.

3. The epoxidized natural latex sponge according to claim 1, wherein the vulcanizing agent is sulfur, the accelerators are zinc diethyldithiocarbamate and 2-mercaptobenzothiazole, the anti-aging agent is 2-mercaptobenzimidazole, the vulcanization activator is zinc oxide, the foaming agent is potassium oleate, the stabilizer is potassium hydroxide, and the gelling agent is sodium fluorosilicate.

4. The epoxidized natural latex sponge according to claim 3, wherein the mass ratio of zinc diethyldithiocarbamate to 2-mercaptobenzothiazole in the accelerator is 5: 3.

5. A method of making an epoxidized natural latex sponge according to any one of claims 1 to 4, comprising the steps of:

6. The method according to claim 5, wherein the dispersion has a total solid content of 50%, the blowing agent has a mass concentration of 20%, and the vulcanization activator and the gelling agent have a mass concentration of 50%.

7. The method according to claim 5, wherein the dispersion is added to the epoxidized natural latex at a stirring temperature of 25 to 35 ℃, for 1 hour, for 24 to 48 hours, and the foaming agent is added at a stirring speed of 600 to 1200rpm and at 200 to 400rpm for homogenization.

8. The preparation method according to claim 5, wherein the setting temperature is 90-100 ℃, the setting time is 10-15 min, the vulcanization temperature is 90-110 ℃, and the vulcanization time is 30-45 min.

9. The preparation method according to claim 5, wherein the drying is hot air drying at 60-70 ℃ for 3-5 h.

10. Use of the epoxidized natural latex sponge of any one of claims 1 to 4 in household goods, medical rehabilitation and cushioning packaging.