CN115403834A

CN115403834A - Epoxidized natural rubber-based water-swellable rubber material and preparation method thereof

Info

Publication number: CN115403834A
Application number: CN202210832343.9A
Authority: CN
Inventors: 张武安
Original assignee: WUXI KUNCHENG NEW MATERIAL TECHNOLOGY CO LTD
Current assignee: WUXI KUNCHENG NEW MATERIAL TECHNOLOGY CO LTD
Priority date: 2022-07-15
Filing date: 2022-07-15
Publication date: 2022-11-29
Anticipated expiration: 2042-07-15
Also published as: CN115403834B

Abstract

The invention relates to an epoxidized natural rubber-based water-swellable rubber material and a preparation method thereof. The invention also provides a preparation method of the epoxidized natural rubber-based water-absorbent expanded rubber, which is characterized in that ENR-50 is added into an open mill for mixing, then cellulose-based water-absorbent resin, cellulose nanocrystal and an alkaline compound serving as a catalyst are added, and zinc oxide, an accelerator, stearic acid, an anti-vulcanization reversion agent and sulfur are sequentially added. Standing for 2-24h after the rubber material is mixed uniformly. Vulcanizing by a flat vulcanizing machine under the conditions of 150 ℃ of temperature, 20MPa of pressure and 45min of time. The multi-component system in the water-swelling rubber prepared by the invention has good compatibility and excellent service performance. And the phenomenon that hydrophilic components are easy to separate out after water absorption is improved through a simple process.

Description

Epoxidized natural rubber-based water-swellable rubber material and preparation method thereof

Technical Field

The invention relates to the technical field of rubber materials, in particular to an epoxidized natural rubber-based water-swellable rubber material and a preparation method thereof.

Background

Since the development of the water-swelling rubber in Japan in the 20 th century and the 70 th century, the unique structure of the water-swelling rubber integrates the characteristics of high water absorption rate, large deformation under low stress, high elasticity, proper strength and the like, and the water-stopping sealing property of the material is endowed. With the continuous emergence of new water-swelling rubber varieties, the application fields of the water-swelling rubber varieties are also continuously widened.

The existing preparation methods of water-swellable rubber are mainly divided into two methods, one is to introduce hydrophilic groups or chain segments into rubber molecular chains by a chemical method; the other is that the rubber-like substance and the hydrophilic substance are combined into a multi-component system by a physical method, and the commercial water-swelling rubber in the market is mainly prepared by the physical method in consideration of the preparation cost, the feasibility of the process and other factors.

From the actual use condition of the commercialized water swellable rubber and the reports and published patents of related documents, the current water swellable rubber has the key problems that (1) in the process of preparing the hydrophilic swellable rubber by a physical method, due to the compatibility problem of a hydrophilic substance and a hydrophobic high polymer material, the hydrophilic substance is difficult to disperse uniformly in a multi-component system, and the mechanical property and the water absorption property of the material are affected, except the problems that the cost is high, and the proper water swelling multiplying power and speed are required to be selected according to the use environment; (2) The precipitation of hydrophilic substances in the use process generates quality loss, and the service performance stability and the reusability of the water-absorbing expansion rubber are seriously influenced. In order to solve the problems, people adopt various methods, for example, chinese patent CN201310320046.7 discloses a compatibilizer of water-swelling nitrile rubber and a preparation method thereof; in Chinese patent CN201711005367.2, a hydrophilized styrene-butadiene rubber is adopted; chinese patent CN201610473187.6 discloses a modified hydrophilic nitrile rubber; chinese patent CN201010520278.3 adopts a modified high water-absorbing resin. In summary, a compatibilizer, modified hydrophilic resin and rubber are mainly introduced to improve the compatibility of a system, increase the interface adhesive force, improve the mechanical property of the material and reduce the mass loss caused by the migration of hydrophilic substances; although the methods obtain better effects, the methods cannot well solve a contradiction existing in the process of preparing the water-swelling rubber by adopting a physical method, namely, the dosage of the super absorbent resin needs to be increased for improving the water absorption rate and the water-swelling multiplying power; the increase of the dosage of the super absorbent resin can cause the reduction of the mechanical property of the material, and particularly, the leaching phenomenon which appears when the super absorbent resin meets water becomes obvious, so that the performance of the water-absorbent expanded rubber is unstable and the repeated use performance is reduced.

The invention takes the commercialized epoxidized natural rubber as a substrate, takes the cellulose-based material as a water absorbing and filling material, and improves the phenomenon that hydrophilic components are easy to separate out after water absorption through a simple process.

Disclosure of Invention

In order to solve the technical problems, the epoxidized natural rubber-based water-swellable rubber material is characterized by comprising the following components in parts by dry weight: epoxidized natural rubber: 100 parts of (A); cellulose-based water-absorbent resin: 15-25 parts; cellulose nanocrystals: 3-10 parts; vulcanizing agent: 0.3-1.5 parts; znO:3-6 parts; vulcanization accelerator (b): 1-2 parts; stearic acid: 0.5-3 parts; catalyst: 0.5-2 parts; anti-reversion agent: 1-2 parts; in which the individual components are compounded and vulcanized to give an epoxidized rubber material, said epoxidized natural rubber being commercially available as ENR-50% by mol, wherein the degree of epoxidation is 50%.

In one embodiment of the present invention, the cellulose-based water absorbent resin is one or more of a cellulose-based grafted acrylic water absorbent, a cellulose-based grafted acrylamide water absorbent, a cellulose-based grafted acrylonitrile water absorbent, a cellulose-based co-grafted acrylamide, and an acrylic water absorbent.

In one embodiment of the present invention, the cellulose nanocrystals have a diameter of 5 to 100nm, a length of 50 to 500nm, and a crystallinity of 60 to 95%.

In one embodiment of the invention, the vulcanizing agent is sulfur.

In one embodiment of the invention, the promoter is one or more of promoter DM and promoter CZ.

In one embodiment of the present invention, the catalyst is one or more of basic compounds KOH, naOH, and sodium phthalate, which catalyze the reaction of hydroxyl, amine, and carboxyl and epoxy groups.

In one embodiment of the invention, the anti-reversion agent is one of Si-69 or PK 900.

The invention also provides a preparation method of the epoxidized natural rubber-based water-swellable rubber material, which is characterized by comprising the following steps of: the method comprises the following steps:

step S1: adding ENR-50 into an open mill, mixing, then adding cellulose-based water-absorbing resin, cellulose nanocrystal and an alkaline compound serving as a catalyst, and then sequentially adding zinc oxide, an accelerator, stearic acid, an anti-vulcanization reversion agent and sulfur;

step S2: standing for 2-24h after the rubber material is mixed uniformly;

and step S3: vulcanizing by a flat vulcanizing machine at 150 ℃,20 MPa and 45min, opening the die, taking out, cooling to room temperature, and cutting to obtain the water-absorbing expansion rubber.

Compared with the prior art, the technical scheme of the invention has the following advantages: the epoxy group in the epoxidized natural rubber, the cellulose-based water-absorbing resin and the hydroxyl group in the cellulose nanocrystal can form a hydrogen bond effect, so that the enhancement of interaction of all phases in a multi-component system and the improvement of system compatibility are facilitated; the sources of the used rubber matrix, the water-absorbent resin and the hydrophilic filler are green and environment-friendly, the precipitation of hydrophilic components after water absorption is inhibited, and the performance stability and the reusability of the water-absorbent expanded rubber are improved.

Detailed Description

Example 1

Adding 100g of ENR-50 into an open mill, and then adding 20g of hydroxyethyl cellulose grafted acrylamide water-absorbing resin and 4g of cellulose nanocrystal; sodium phthalate, 1g; znO,5g; 1.5 parts of accelerator DM; 0.5 part of accelerator CZ; stearic acid. 2g of the total weight of the mixture; 1.5g of anti-reversion agent Si-69; 1.2g of sulfur. The rubber material is placed for 12 hours after being mixed evenly. Vulcanizing by a flat vulcanizing machine at 150 ℃,20 MPa and 45min, opening the die, taking out, cooling to room temperature, and cutting to obtain the water-absorbing expansion rubber.

Example 2

Adding 100g of ENR-50 into an open mill, and then adding 20g of HEC-g- (AM-AA) water-absorbent resin and 5g of cellulose nanocrystal; sodium phthalate, 1.5g; znO,5g; 1.5 parts of accelerator DM; 0.5 part of accelerator CZ; stearic acid. 2g of the total weight of the mixture; 1.5g of anti-reversion agent Si-69; 1.5g of sulfur. Standing for 12h after the rubber material is mixed uniformly. Vulcanizing at 150 deg.C under 20MPa for 45min by a flat vulcanizing machine, opening the mold, cooling to room temperature, and cutting to obtain the final product.

Example 3

Adding 100g of ENR-50 into an open mill, and then adding 20g of carboxymethyl cellulose grafted sodium acrylate water-absorbent resin and 5g of cellulose nanocrystal; sodium phthalate, 1.5g; znO,5g; 1.5 parts of accelerator DM; 0.5 part of promoter CZ; stearic acid. 2g of the total weight of the mixture; anti-reversion agent PK900,1g; sulfur, 1.5g. Standing for 12h after the rubber material is mixed uniformly. Vulcanizing by a flat vulcanizing machine at 150 ℃,20 MPa and 45min, opening the die, taking out, cooling to room temperature, and cutting to obtain the water-absorbing expansion rubber.

The epoxidized natural rubber-based water swellable rubbers obtained in examples 1, 2 and 3 and the comparative sample were subjected to the test, and the test results were as follows:

water absorption and mechanical property table of epoxidized natural rubber-based water-swellable rubber

All tested in three ways:

water absorption:

approximately 500mg samples of dried flakes were cut, accurately weighed, and soaked in distilled water at ambient temperature (approximately 28-30 ℃). After equilibration, the swollen sample was removed from the distilled water, carefully removed of surface moisture with blotter paper and the weight of the sample was measured immediately. The water absorption was calculated by the following formula.

Water absorption = (mass before water absorption-mass after water absorption)/mass before water absorption

The above experiment was repeated three times and the average was taken.

Secondary water absorption:

the water-swellable rubber saturated with water was weighed and dried in a forced air oven at 70 ℃ until the water was completely lost, and the water absorption test was conducted again. The same experiment was repeated three times and the average was taken.

Determination of tensile strength and elongation at break:

refer to GB/T528-2009 determination of tensile stress strain performance of vulcanized rubber or thermoplastic rubber.

The comparative samples were carried out as follows:

adding 100g of ENR-50 into an open mill, and then adding 20g of HEC-g- (AM-AA) water-absorbent resin and 4g of cellulose nanocrystal; znO,6g; 1 part of an accelerator TBBS; stearic acid. 2g of the total weight of the mixture; sulfur, 2g. Standing for 12h after the rubber material is mixed uniformly. Vulcanizing at 150 deg.C under 20MPa for 15min by a flat vulcanizing machine, opening the mold, cooling to room temperature, and cutting to obtain the water-absorbing expansion rubber.

As can be seen by comparison with example 1, the comparative sample has no basic compound added as a catalyst, no anti-reversion agent added, and no reduction in sulfur usage. The vulcanization time is not prolonged.

From the comparison of performances, the primary water absorption rate and the mechanical property of the sample 1 are similar to those of the comparative sample, the sulfur dosage in the sample 1 is less, but an alkaline compound for catalyzing the reaction of hydroxyl, amine, carboxyl and epoxy groups is introduced, and the vulcanization time is increased. So that functional groups such as hydroxyl groups on the cellulose-based water-absorbing resin and the cellulose nanocrystals can react with epoxy groups, and the system can possibly form another cross-linked network, so that under the condition that the varieties and the dosages of the cellulose-based water-absorbing resin and the cellulose nanocrystals are not changed, the primary water absorption rate and the mechanical property of the two samples are similar. However, in example 1, the secondary water absorption rate remained at a high level because precipitation of the hydrophilic component after water absorption was suppressed.

The main difference between examples 1, 2 and 3 is that the water-absorbing resins used are different in the types of hydroxyethyl cellulose grafted acrylamide, HEC-g- (AM-AA) and sodium carboxymethyl cellulose grafted acrylate, and the saturated distilled water absorption capacities of the hydroxyethyl cellulose grafted acrylamide, the HEC-g- (AM-AA) and the sodium carboxymethyl cellulose grafted acrylate are 518g/g, 832g/g and 995g/g respectively. From the comparison of the performances of the three examples, the kind of the water-absorbent resin has little influence on the mechanical properties, but the larger the water-absorbing capacity of the water-absorbent resin is, the larger the primary water absorption of the water-swellable rubber is, and the larger the decrease in the secondary water absorption is. However, in general, the method provided by the invention can inhibit the precipitation of hydrophilic components after water absorption, and improve the performance stability and the reusability of the water-swellable rubber.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.

Claims

1. An epoxidized natural rubber-based water-swellable rubber material is characterized by comprising the following components in parts by dry weight: epoxidized natural rubber: 100 parts of a binder; cellulose-based water-absorbent resin: 15-25 parts; cellulose nanocrystals: 3-10 parts; vulcanizing agent: 0.3-1.5 parts; znO:3-6 parts; vulcanization accelerator (b): 1-2 parts; stearic acid: 0.5-3 parts; catalyst: 0.5-2 parts; anti-reversion agent: 1-2 parts; in which the individual components are compounded and vulcanized to give an epoxidized rubber material, said epoxidized natural rubber being commercially available as ENR-50% by mol, wherein the degree of epoxidation is 50%.

2. The epoxidized natural rubber-based water-swellable rubber material as claimed in claim 1, wherein: the cellulose-based water-absorbing resin is one or more of cellulose-based grafted acrylic acid water absorbent, cellulose-based grafted acrylamide water absorbent, cellulose-based grafted acrylonitrile water absorbent, cellulose-based co-grafted acrylamide and acrylic acid water absorbent.

3. The epoxidized natural rubber-based water-swellable rubber material as claimed in claim 1, wherein: the diameter of the cellulose nanocrystal is 5-100nm, the length of the cellulose nanocrystal is 50-500nm, and the crystallinity of the cellulose nanocrystal is 60-95%.

4. The epoxidized natural rubber-based water-swellable rubber material according to claim 1, characterized in that: the vulcanizing agent is sulfur.

5. The epoxidized natural rubber-based water-swellable rubber material as claimed in claim 1, wherein: the catalyst is alkaline compounds KOH, naOH and Mg (OH) for catalyzing the reaction of hydroxyl, amino, carboxyl and epoxy groups ₂ And sodium phthalate.

6. The epoxidized natural rubber-based water-swellable rubber material as claimed in claim 1, wherein: the catalyst is one or more of alkaline compounds KOH, naOH and sodium phthalate which catalyze the reaction of hydroxyl, amido, carboxyl and epoxy groups.

7. The epoxidized natural rubber-based water-swellable rubber material as claimed in claim 1, wherein: the anti-reversion agent is one of Si-69 or PK 900.

8. A process for producing the epoxidized natural rubber-based water-swellable rubber material according to any one of claims 1 to 7, characterized by comprising: the method comprises the following steps:

step S1: adding ENR-50 into an open mill, mixing, then adding cellulose-based water-absorbing resin, cellulose nanocrystals and an alkaline compound serving as a catalyst, and then sequentially adding zinc oxide, an accelerator, stearic acid, an anti-reversion agent and sulfur;

step S2: standing for 2-24h after the rubber material is mixed uniformly;