CN116426045A - Rubber micro-nano crystal composite material with excellent gas barrier property and preparation method thereof - Google Patents

Abstract

The invention relates to a rubber micro-nano crystal composite material with excellent gas barrier property and a preparation method thereof. The composite material consists of the following components in parts by weight: 5-50 parts of crystalline rubber, 50-95 parts of amorphous rubber, 0-5 parts of anti-aging agent, 0-75 parts of filler and 0-20 parts of other auxiliary agents. Crystalline rubber is uniformly dispersed in the composite material in the form of lamellar, fibrous and dendritic micro-nanocrystals, so that the path of gas passing through the composite material is hindered or prolonged, the gas barrier property is improved, and the thermo-oxidative aging resistance is improved.

Description

A rubber micro-nanocrystalline composite material with excellent gas barrier properties and its preparation preparation method

technical field

The invention relates to the technical field of rubber, in particular to a uniformly dispersed rubber composition containing crystalline rubber micro-nano crystals and a preparation method thereof. The composition can be used in the preparation of gas barrier rubber products.

Background technique

Rubber, as an important polymer material, is more and more widely used in various fields such as daily life, modern industry, agriculture, medicine, national defense and military. Medical, rubber shoes and many other rubber products.

Whether it is NR, or SBR, BR and IR, the rubber macromolecular chain structure contains unsaturated bonds and active allyl hydrogen or tertiary hydrogen atoms, which are extremely vulnerable to heat, light, pressure, and even natural environments. The attack of oxygen atoms reduces its service life, and in severe cases, it will affect economic benefits and even life and property safety.

The most commonly used and most effective way to improve the heat and oxygen aging resistance of rubber products is to add antioxidants. However, antioxidants are generally small molecular compounds, which are volatile and have blooming problems, which will lead to a decline in the antioxidant performance of rubber products. In addition, the precipitation of antioxidants can also cause environmental pollution, especially for some rubber products that are in contact with food and medicines. The precipitation of antioxidants will cause adverse reactions such as food deterioration, drug failure or poisoning. In addition, the gas barrier properties of rubber products can be improved by adding fillers, and the thermal and oxygen aging resistance of rubber products can also be improved to a certain extent. However, it is well known that fillers are very easy to agglomerate in the rubber matrix and cause stress concentration, reducing the performance of rubber products. Therefore, it is of great significance to develop new, effective and environmentally friendly methods to improve the thermal and oxidative aging resistance of rubber substrates for improving the service life, safety and economy of rubber products and even all polymer materials.

Contents of the invention

In view of the defects of the prior art mentioned above, one of the purposes of the present invention is to provide a rubber micro-nanocrystalline composite material with excellent gas barrier properties, and to control the crystal morphology of crystalline rubber in the rubber composite material to achieve gas barrier And delay gas permeation, improve the thermo-oxidative aging performance of rubber composite materials and products.

The second object of the present invention is to provide a preparation method of the rubber micro-nano crystal composite material, which realizes the formation of crystalline rubber micro-nano crystals through treatment.

The rubber micro-nano crystal composite material of the present invention is composed of the following formulations in parts by weight: 5-50 parts of crystalline rubber, 50-95 parts of non-crystalline rubber, 0-5 parts of anti-aging agent, 0-75 parts of filler, and other additives 0 to 20 parts of the agent; wherein the crystalline rubber exists in the composite material in the form of micro-nano crystals that hinder gas permeation.

As preferably, the crystalline rubber of the present invention is one or both of trans polydiene rubber, high ethylene content ethylene propylene rubber, and chloroprene rubber; the non-crystalline rubber is natural rubber, butadiene rubber , styrene-butadiene rubber, butyl rubber, nitrile rubber and its derivatives, or two or more.

The trans polydiene rubber of the present invention is trans-1,4-butadiene-isoprene copolymer rubber, trans-1,4-polyisoprene, trans-1,4-polybutylene Diene, trans-1,4-structure molar content is greater than 50 mol%.

Preferably, the weight average molecular weight of the trans-1,4-butadiene-isoprene copolymer rubber of the present invention is 100,000 to 1,200,000, the molecular weight distribution is 3 to 20, and the trans-1,4-structure content is greater than 50 mol %, the content of butadiene units in the copolymerized rubber is 5-95%, and the melting enthalpy of crystallization is 5-60 J/g.

Other additives of the present invention are one or two or more of zinc oxide, stearic acid, magnesium oxide, softener, coupling agent, activator, accelerator and sulfur.

In the present invention, the softening agent that can adopt is aromatic hydrocarbon oil, cycloalkane oil, modified soybean oil, phenolic resin, resorcinol formaldehyde resin, rosin, terpene resin, coumarone resin, carbon five resin, dicyclopentadiene One or two or more of diene resin DCPD, AMS resin, low molecular weight polybutadiene, low molecular weight polyisoprene, low molecular weight butadiene-isoprene copolymer.

In the present invention, the accelerator that can be used is one or two or more of the accelerators M, DM, ZDT, TMTD, CZ, DZ, ZDC, NS, MDB, DETU, AC, DPG, DOTG. In addition, the sulfur in the present invention may be soluble sulfur or insoluble sulfur.

In the present invention, the crystalline rubber exists in the form of crystals or partial crystals in the composite material, and the morphology of the micro-nano crystals is sheet, layered, fibrous, and dendritic, and the smallest dimension of the crystals is 5nm-100μm. The thickness of the flaky and layered crystal morphology is 5-100nm, and the aspect ratio is 20-1000:1; the diameter of the fibrous and dendritic crystal morphology is 5-100nm, and the aspect ratio is 20-1000:1.

Another object of the present invention is to provide a kind of preparation method of rubber micro-nano crystal composite material, it is characterized in that comprising the following steps:

1) Add non-crystalline rubber and at least half of the anti-aging agent, filler and other additives except sulfur and accelerator to the rubber mixing equipment. The mixing temperature is 10 ° C ~ 180 ° C. After fully mixing, the mixing Glue, next piece;

2) Add the crystalline rubber and the remaining anti-aging agent, filler and other additives except sulfur and accelerator to the rubber mixing equipment. The mixing temperature is from the melting point of the crystalline rubber to 180°C. After fully mixing, the obtained Mixed rubber, lower piece;

3) annealing the mixed rubber obtained in step 2) at a temperature of 10° C. to 200° C. for 0.1 to 10 hours;

4) Add the compounded rubber in steps 1) and 3) to the rubber mixing equipment, add sulfur and accelerator, and mix at a mixing temperature of 20°C to 75°C.

5) vulcanizing the film obtained in step 4) to obtain a rubber micro-nano crystal composite material;

Wherein, the rubber mixing equipment is one of an open rubber mixing machine, a closed rubber mixing machine, a screw extruder, and a kneader.

The advantage of the invention is that the crystalline rubber is uniformly dispersed in the rubber micro-nano crystal composite material, which hinders or prolongs the path of gas passing through the composite material, improves the gas barrier property, and improves the heat-oxidative aging resistance. The gas therein can be one or a mixture of two or more of air, oxygen, ozone, and organic solvent vapor.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with specific embodiments, which will help the understanding of the present invention. However, the present invention is not limited to the following embodiments, and the scope of rights of the present invention should be defined by the claims.

Example 1

The following formula is used: 50 parts of NR, 50 parts of TBIR, 2 parts of stearic acid, 3 parts of zinc oxide, 2 parts of antioxidant RD, 2.4 parts of accelerator CZ, and 1.5 parts of sulfur.

Add NR, stearic acid, zinc oxide, and half of the anti-aging agent into the internal mixer, control the temperature of the internal mixer to not exceed 140°C, and mix for 2 minutes to obtain NR compound rubber, which is ready for use; TBIR and the other half Add the anti-aging agent into the internal mixer, control the temperature of the internal mixer to not exceed 130°C, and banbury for 2 minutes to obtain the TBIR compound rubber. After standing for 8 hours, the compound compound is treated at 170°C for 2 minutes. Then lower it to 85°C for 2 hours, then lower it to room temperature, and set aside; put the NR rubber and TBIR rubber in the internal mixer, add sulfur and accelerator, control the temperature of the internal mixer to 60°C, and mix for 1 minute. The lower sheet: vulcanize the mixed rubber composition at 135° C. under the normal vulcanization time of the process to obtain a rubber micro-nano crystal composite material.

After testing, the TBIR crystallization in the TBIR compound produces layered crystals with a thickness of 15-30nm, a maximum extension size of the crystals of 1500nm, and an oxygen permeability coefficient of 5.12*10 ^-15 cm ³ ·cm/cm ² ·s·Pa . After testing the vulcanizate, the layered crystal thickness of TBIR increases to about 35-100nm, and the maximum extension size of the crystal decreases to about 600-1200nm. After the vulcanizate is aged in hot air at 100°C for 72 hours, the tensile strength retention rate is 92.4 %, the retention rate of elongation at break was 92%.

Comparative example 1

The following formula is used: 100 parts of NR, 2 parts of stearic acid, 3 parts of zinc oxide, 2 parts of antioxidant RD, 2.4 parts of accelerator CZ, and 1.5 parts of sulfur.

Add NR, stearic acid, zinc oxide, and anti-aging agent into the internal mixer, control the temperature of the internal mixer to not exceed 140°C, and banbury for 2 minutes to obtain NR compound rubber, which is ready for use; add NR compound rubber to In the internal mixer, add sulfur and accelerator, control the temperature of the internal mixer to 60°C, mix for 1min, and then release the tablet; vulcanize the mixed rubber composition at 135°C and the normal vulcanization time of the process to obtain a natural rubber composite material.

After testing, no crystalline crystals were found in the NR compound, and the oxygen permeability coefficient was 7.45*10 ^-13 cm ³ ·cm/cm ² ·s·Pa. It can be seen that compared with Example 1, the oxygen permeability coefficient of the pure NR compound after heat treatment without adding TBIR is increased by 2 orders of magnitude, indicating that its barrier property to oxygen is significantly reduced. After NR vulcanizate was aged in hot air at 100°C for 72 hours, the retention rate of tensile strength was 75.2%, and the retention rate of elongation at break was 68%.

Example 2

Except that the TBIR compound was treated at 200°C for 1 min, then lowered to 155°C for 1 hour, and then lowered to 70°C for 1 hour, the rest was the same as in Example 1.

After testing, the TBIR crystallization in the TBIR compound produces dendritic and layered crystals. The overall size of the dendrites is about 100 microns, the diameter of the dendrites is about 20-40nm, and the oxygen permeability coefficient is 6.89*10 after testing. ^-15 cm ³ ·cm/cm ² ·s·Pa. After the vulcanizate was aged in hot air at 100°C for 72 hours, the retention rate of tensile strength was 95.4%, and the retention rate of elongation at break was 98%.

Claims (10)

1. The rubber micro-nano crystal composite material is characterized by comprising the following components in parts by weight: 5-50 parts of crystalline rubber, 50-95 parts of amorphous rubber, 0-5 parts of anti-aging agent, 0-75 parts of filler and 0-20 parts of other auxiliary agents; wherein the crystalline rubber exists in the composite material in a micro-nano crystal morphology which plays a role in blocking gas permeation.

2. The rubber micro-nano crystal composite material according to claim 1, wherein the crystalline rubber is one or two of trans polydiene rubber, ethylene propylene rubber with high ethylene content and chloroprene rubber; the non-crystalline rubber is one or more of natural rubber, butadiene rubber, styrene-butadiene rubber, butyl rubber, nitrile rubber and derivatives thereof.

3. The rubber micro-nano crystal composite material according to claim 2, wherein the trans polydiene rubber is trans-1, 4-butadiene-isoprene copolymer rubber, trans-1, 4-polyisoprene and trans-1, 4-polybutadiene, the molar content of the trans-1, 4-structure is more than 50mol%, and the crystallization melting enthalpy is 5-120J/g.

4. The rubber micro-nano crystal composite material according to claim 3, wherein the trans-1, 4-butadiene-isoprene copolymer rubber has a weight average molecular weight of 10-120 ten thousand, a molecular weight distribution of 3-20, a trans-1, 4-structure content of more than 50mol%, a butadiene unit content in the copolymer rubber of 5-95%, and a crystallization melting enthalpy of 5-60J/g.

5. The rubber micro-nano crystal composite material according to claim 1, wherein the other auxiliary agent is one or two or more of zinc oxide, stearic acid, magnesium oxide, a coupling agent, a softener, an activator, an accelerator and sulfur.

6. The rubber micro-nano crystal composite material according to claim 1, wherein the crystalline rubber exists in a crystal or partial crystal form in the composite material, the micro-nano crystal form is sheet-shaped, lamellar, fibrous and dendritic, and the minimum dimension of the crystal is 5 nm-100 μm.

7. The rubber micro-nano crystal composite material according to claim 6, wherein the thickness of the flaky and lamellar crystal morphology is 5-100 nm, and the ratio of the diameter to the thickness is 20-1000:1; the diameter of the fibrous and dendritic crystal morphology is 5-100 nm, and the length-diameter ratio is 20-1000:1.

8. The rubber micro-nano composite material according to claim 6, wherein the crystalline rubber is uniformly dispersed in the composite material, and the path of gas passing through the composite material is hindered or prolonged, so that the gas barrier property is improved, and the thermo-oxidative aging resistance is improved.

9. The rubber micro-nano composite material according to claim 8, wherein the gas is one or two or more of air, oxygen, ozone and organic solvent vapor.

10. The preparation method of the rubber micro-nano crystal composite material comprises the following steps:

1) Adding amorphous rubber, at least half of an anti-aging agent, a filler and other auxiliary agents except for a sulfur yellow accelerator into rubber mixing equipment, mixing at the temperature of 10-180 ℃, fully mixing to obtain a mixed rubber, and discharging;

2) Adding crystalline rubber, the rest of anti-aging agent, filler and other auxiliary agents except for sulfur yellow and accelerator into rubber mixing equipment, mixing at the temperature of 180 ℃ of the melting point of the crystalline rubber, fully mixing to obtain mixed rubber, and discharging;

3) Annealing the rubber compound obtained in the step 2) for 0.1-10 hours at the temperature of 10-200 ℃;

4) Adding the rubber compound in the steps 1) and 3) into rubber mixing equipment, adding sulfur and an accelerator, mixing at the mixing temperature of 20-75 ℃, fully mixing, and then blanking;

5) Vulcanizing the film obtained in the step 4) to obtain a rubber micro-nano crystal composite material;

wherein, the rubber mixing equipment is one of an open rubber mixing machine, an internal rubber mixing machine, a screw extruder and a kneader.