Foaming brominated butyl rubber composite material with low density and high mechanical property and preparation method thereof

Abstract

The invention belongs to the technical field of polymer-based composite foam materials, and particularly relates to a low-density and high-mechanical-property brominated butyl rubber composite foam material and a preparation method thereof.The preparation method comprises the following steps that raw brominated butyl rubber, reinforcing filler, a foaming agent and the like are mixed through an internal mixer; performing secondary banburying to obtain a uniformly mixed brominated butyl rubber compound; step 3, discharging bubbles in the rubber compound by using an open mill; and 3, carrying out high-temperature curing foaming on the rolled rubber compound by using a plate vulcanizer to obtain the low-density and high-performance brominated butyl rubber foaming composite material. The obtained brominated butyl rubber composite material with low density and high mechanical property has the characteristics of simple preparation process, light weight, uniform cells, high cell density and high tensile strength; the density of the prepared foamed rubber is 0.35 g / cm < 3 >, and is lighter than that of natural rubber by more than 60%; the invention is suitable for the fields of building materials, automobile industry, medical equipment and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer-based composite foaming materials, and particularly relates to a foamed bromobutyl rubber composite material for low density and high mechanical properties and a preparation method thereof. Background Art

[0002] Bromobutyl rubber is modified by bromination of butyl rubber. While possessing the excellent airtightness and chemical resistance of butyl rubber, the presence of bromine atoms accelerates the vulcanization rate of the material. Therefore, it is widely used in tire linings, medical bottle stoppers, etc. In the chemical foaming process of rubber, vulcanization and foaming occur simultaneously. Therefore, the matching problem between the expansion of bubble nuclei and the curing and shaping of rubber is an inevitable problem for rubber foaming materials. Therefore, it is particularly important to control the matching of the foaming rate and the crosslinking rate of the material on the density, cell size, and mechanical properties of the material.

[0003] Publication number "CN 116554533 B" discloses "A Bromobutyl Rubber / Polyethylene Thermal Insulation and Buffer Material and Its Preparation Process". This process prepares a bromobutyl rubber / polyethylene composite foaming material with small average cell size and small shrinkage rate through a physical foaming method. However, during the preparation process, supercritical nitrogen foaming technology needs to be used to obtain the foaming sample, and high temperature and high pressure are required during the preparation process. Therefore, there are problems such as high equipment requirements, harsh preparation conditions, complex process, high manufacturing cost, and it is not suitable for large-scale industrial production.

[0004] Polymer-based composite foaming materials have the characteristics of light weight, heat insulation, sound insulation, and high energy absorption and buffering performance, and are widely used in materials such as shoe materials, automotive interior parts, and sound insulation boards. They are one of the best choices for polymers to reduce costs. However, most polymer-based composite materials have low mechanical strength, poor stability, and decreased durability, resulting in low usage rate of the prepared products. In order to solve the problems of the prior art, publication number "CN 117384444 A" discloses "A Lightweight and Ultra-Wear-Resistant Foamed Injection Rubber Material", which uses ethylene-vinyl acetate copolymer, ethylene propylene diene monomer rubber and bromobutyl rubber in compounding. However, it still has the following problems: the proportion of bromobutyl rubber in it is extremely small. To ensure the compatibility of multiple materials, compatibilizers and other components need to be added, which increases the raw material cost. At the same time, the process becomes complex, and subsequent treatment is required after the open mill, increasing the preparation cost. The foaming and crosslinking rates cannot be controlled, and the product quality is unstable. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method of a foamed bromobutyl rubber composite material for low density and high mechanical properties, so as to overcome the problems of complex process, high preparation cost, inability to control the foaming and crosslinking rates, and unstable product quality existing in the prior art.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a preparation method of a foamed bromobutyl rubber composite material for low density and high mechanical properties, comprising the following steps:

[0007] Step 1: Mix 70 parts by weight of bromobutyl rubber with 30 parts by weight of styrene-butadiene-styrene block copolymer, 5-15 parts by weight of silica, 20-40 parts by weight of carbon black, 3-8 parts by weight of zinc oxide, 1-3 parts by weight of stearic acid, and 3-5 parts by weight of antioxidant in a mixer for sufficient mixing;

[0008] Step 2: Add the mixed rubber in Step 1, 3-5 parts by weight of chemical blowing agent, 0.1-1 part by weight of sulfur, 0.1-0.5 part by weight of dicumyl peroxide, and 3-5 parts by weight of accelerator into the mixer, and mix to obtain a mixed rubber;

[0009] Step 3: Roll the mixed rubber obtained in Step 2 on an open mill for 10-20 min, and cut it into sheets;

[0010] Step 4: Preheat the temperature of the inner mold of the vulcanizer to 160-180 °C, then spray a release agent, and place the sheet in Step 3 into the vulcanizer for high-temperature curing and foaming to obtain a foamed bromobutyl rubber composite material for low density and high performance.

[0011] Further, in the above Step 1, the bromobutyl rubber has the brand of ExxonMobil 2255, its molecular weight is 300,000-450,000, the bromine atom content is 1.8-2.2%, the Mooney viscosity ML1+8@125 °C is 32-35, and the carbon black is conductive carbon black or acetylene black.

[0012] Further, in the above Step 1, the antioxidant is N-isopropyl-N-phenyl-p-phenylenediamine, styrenated phenol or N,N-diphenyl-p-phenylenediamine.

[0013] Further, in the above Step 2, the chemical blowing agent is AC or OBSH, and the accelerator is N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylene benzothiazole-2-sulfenamide or 2-mercaptobenzothiazole.

[0014] Further, in the above Step 4, the vulcanization pressure maintaining time is 450-600 s, and the vulcanization pressure is maintained at 10 MPa.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. By introducing styrene-butadiene-styrene block copolymer into bromobutyl rubber, the density of the foamed rubber prepared by the present invention is 0.35 g / cm 3, which is more than 60% lighter than natural rubber. In addition, styrene-butadiene-styrene block copolymer is a thermoplastic elastomer. Compared with polyethylene, styrene-butadiene-styrene block copolymer has better compatibility with rubber and is not easily phase-separated after blending; SBS can be processed at 100 °C, reducing the risk of thermal aging of rubber when blended with rubber; after blending with SBS, the fatigue resistance and wear resistance of BIIR can be enhanced. While reducing the foaming density of bromobutyl rubber, it endows it with resilience, wear resistance and improves mechanical properties. By introducing silica to reinforce bromobutyl rubber, silica can also act as a heterogeneous nucleating agent to promote the formation of its pores, further reducing the density of bromobutyl rubber materials.

[0017] 2. The chemical foaming technology adopted in this technology foams the composite material at high temperature by directly adding a chemical foaming agent. The foaming agent directly releases gas at high temperature to turn the composite material into a foamed material. The preparation process is simple, the steps are simple, and the energy consumption is lower. The prepared foamed bromobutyl rubber composite material has the characteristics of light weight (0.35 g / cm 3 ), small average pore size (72.6 μm), high tensile strength (4.76 MPa) and high elongation at break (1267%).

[0018] 3. The preparation method adopted in the present invention is simple and effective, with low cost and simple process. It can effectively control the foaming and crosslinking rates, the product quality is stable, it is suitable for large-scale industrial production, and is applicable to fields such as building materials, automotive industry, and medical equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is an electron scanning electron microscope (SEM) image of the cross-section of the low-density and high-mechanical-property foamed bromobutyl rubber composite foaming material in Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0021] A preparation method of a low-density and high-mechanical-property foamed bromobutyl rubber composite foaming material of the present invention specifically includes the following steps:

[0022] Step 1: Mix 70 parts by weight of bromobutyl rubber with 30 parts by weight of styrene-butadiene-styrene block copolymer, 5-15 parts by weight of silica, 20-40 parts by weight of carbon black, 3-8 parts by weight of zinc oxide, 1-3 parts by weight of stearic acid, and 3-5 parts by weight of antioxidant in a mixer; the bromobutyl rubber has the brand name ExxonMobil 2255, its molecular weight is 300,000-450,000, the bromine atom content is 1.8-2.2%, and the Mooney viscosity (ML1+8@125 °C) is 32-35; the carbon black is conductive carbon black or acetylene black.

[0023] Step 2: Then, add the kneaded rubber compound obtained in Step 1, 3 - 5 parts by weight of a chemical blowing agent, 0.1 - 1 part by weight of sulfur, 0.1 - 0.5 part by weight of dicumyl peroxide into a mixer, and knead with 3 - 5 parts by weight of an accelerator to obtain a kneaded rubber compound; the chemical blowing agent is AC or OBSH, and the accelerator is N - cyclohexyl - 2 - benzothiazolesulfenamide, N - oxydiethylene benzothiazole - 2 - sulfenamide or 2 - mercaptobenzothiazole.

[0024] Step 3: Roll the kneaded rubber compound obtained in Step 2 on an open mill for 10 - 20 min, and cut it into sheets.

[0025] Step 4: Pre - heat the temperature of the inner - embedded mold of the vulcanizer to 160 - 180 °C, then spray a mold release agent, put the sheet obtained in Step 3 into the vulcanizer for high - temperature curing and foaming, with a vulcanization pressure - holding time of 450 - 600 s and a vulcanization pressure maintained at 10 MPa, to obtain a low - density and high - performance foamed bromobutyl rubber composite material.

[0026] Example 1, a preparation method of a low - density and high - mechanical - property foamed bromobutyl rubber composite foaming material, specifically includes the following steps:

[0027] Step 1: Thoroughly knead 70 parts by weight of bromobutyl rubber (BIIR), 30 parts by weight of styrene - butadiene - styrene block copolymer (SBS), 5 parts by weight of white carbon black, 20 parts by weight of conductive carbon black, 3 parts by weight of zinc oxide, 1 part by weight of stearic acid, and 3 parts by weight of N - isopropyl - N - phenyl - p - phenylenediamine in a mixer.

[0028] Step 2: Then, add 0.1 part by weight of dicumyl peroxide, 1 part by weight of sulfur, 3 parts by weight of N - cyclohexyl - 2 - benzothiazolesulfenamide, and 3 parts by weight of AC into the mixer, and knead to obtain a kneaded rubber compound.

[0029] Step 3: Roll the obtained kneaded rubber compound on an open mill for 15 min, discharge the air bubbles in the kneaded rubber compound, and cut it into sheets with a size of 10 cm × 8 cm.

[0030] Step 4: Pre - heat the temperature of the inner - embedded mold of the vulcanizer to 160 °C, set the pressure to 10 MPa, put it into the vulcanizer for 450 s of high - temperature curing and foaming, to obtain a low - density and high - mechanical - property foamed bromobutyl rubber composite foaming material.

[0031] Example 2, a preparation method of a low - density and high - mechanical - property foamed bromobutyl rubber composite foaming material, specifically includes the following steps:

[0032] Step 1: Thoroughly mix 70 parts by weight of bromobutyl rubber (BIIR), 30 parts by weight of styrene-butadiene-styrene block copolymer (SBS), 8 parts by weight of silica, 40 parts by weight of conductive carbon black, 5 parts by weight of zinc oxide, 2 parts by weight of stearic acid, and 3 parts by weight of N-isopropyl-N-phenyl-p-phenylenediamine in a Banbury mixer;

[0033] Step 2: Then add 0.4 parts by weight of dicumyl peroxide, 0.7 parts by weight of sulfur, 3 parts by weight of N-cyclohexyl-2-benzothiazole sulfenamide, and 4 parts by weight of OBSH to the Banbury mixer and mix to obtain a mixed rubber;

[0034] Step 3: Roll the obtained mixed rubber on a two-roll mill for 15 min to discharge the air bubbles in the mixed rubber, and cut it into sheets with a specification of 10 cm × 8 cm;

[0035] Step 4: Preheat the temperature of the inner mold of the vulcanizer to 160 °C, set the pressure to 10 MPa, put it into the vulcanizer for high-temperature curing and foaming for 480 s to obtain a low-density and high-mechanical-property foamed bromobutyl rubber composite foaming material.

[0036] Example 3, a preparation method of a low-density and high-mechanical-property foamed bromobutyl rubber composite foaming material, specifically includes the following steps:

[0037] Step 1: Thoroughly mix 70 parts by weight of bromobutyl rubber (BIIR), 30 parts by weight of styrene-butadiene-styrene block copolymer (SBS), 8 parts by weight of silica, 40 parts by weight of acetylene carbon black, 5 parts by weight of zinc oxide, 1 part by weight of stearic acid, and 5 parts by weight of N,N-diphenyl-p-phenylenediamine in a Banbury mixer;

[0038] Step 2: Then add 0.4 parts by weight of dicumyl peroxide, 0.7 parts by weight of sulfur, 5 parts by weight of 2-mercaptobenzothiazole, and 5 parts by weight of AC to the Banbury mixer and mix to obtain a mixed rubber;

[0039] Step 3: Roll the obtained mixed rubber on a two-roll mill for 15 min to discharge the air bubbles in the mixed rubber, and cut it into sheets with a specification of 10 cm × 8 cm;

[0040] Step 4: Preheat the temperature of the inner mold of the vulcanizer to 160 °C, set the pressure to 10 MPa, put it into the vulcanizer for high-temperature curing and foaming for 600 s to obtain a low-density and high-mechanical-property foamed bromobutyl rubber composite foaming material.

[0041] The low-density and high-mechanical-property foamed bromobutyl rubber composite foaming material prepared by the mechanical blending method of the present invention, wherein the electron scanning electron microscope (SEM) of the cross-section of Example 2 is as Figure 1As shown, it can be seen that its average pore size is small (72.6 μm), and at the same time it has the characteristics of being lightweight (0.35 g / cm 3 ), high tensile strength (4.76 MPa) and high elongation at break (1267%). Therefore, Example 2 is the best example.

[0042] The above description is an illustration of the specific implementation of the present invention, rather than a limitation thereof. Those skilled in the relevant technical field can also make various equivalent technical solutions without departing from the scope of the present invention. Therefore, all equivalent technical solutions should be included in the scope of patent protection of the present invention.

Claims

1. A method for preparing a low-density, high-mechanical-performance foamed bromobutyl rubber composite material, characterized in that: The following steps are involved: Step 1, 70 parts by weight of brominated butyl rubber, 30 parts by weight of styrene-butadiene-styrene block copolymer, 5-15 parts by weight of white carbon black, 20-40 parts by weight of carbon black, 3-8 parts by weight of zinc oxide, 1-3 parts by weight of stearic acid, and 3-5 parts by weight of antioxidant are fully mixed in an internal mixer; Step 2: adding the rubber mix prepared in step 1, 3-5 parts by weight of a chemical foaming agent, 0.1-1 parts by weight of sulfur, 0.1-0.5 parts by weight of dicumyl peroxide and 3-5 parts by weight of an accelerator into an internal mixer, and mixing to obtain a rubber mix; Step 3, rolling the rubber mixture obtained in step 2 on a mixing mill for 10-20 minutes to cut it into sheets; Step 4: preheat the temperature of the embedded mold in the vulcanizer to 160-180° C., then spray the release agent, put the sheet layer in the vulcanizer for high-temperature curing and foaming, and obtain a low-density, high-performance foamed bromobutyl rubber composite material.

2. The method for preparing a low-density, high-performance foamed bromobutyl rubber composite material according to claim 1, characterized in that: In the step 1, the brand of the brominated butyl rubber is ExxonMobil 2255, the molecular weight of which is 300,000-450,000, the bromine atom content of which is 1.8-2.2%, the Mooney viscosity ML1+8@125°C is 32-35, and the carbon black is conductive carbon black or acetylene carbon black.

3. The method for preparing a low-density, high-performance foamed bromobutyl rubber composite material according to claim 2, characterized in that: In the step 1, the antioxidant is N-isopropyl-N-phenyl-p-phenylenediamine, styrenated phenol or N,N-diphenyl-p-phenylenediamine.

4. The method for preparing a low-density and high-mechanical-performance foamed bromobutyl rubber composite material according to claim 3, characterized in that: In the step 2, the chemical foaming agent is AC or OBSH, and the accelerator is N-cyclohexyl-2-benzothiazole sulfenamide, N-oxydiethylenebenzothiazole-2-sulfenamide or 2-mercaptobenzothiazole.

5. The method for preparing a low-density and high-mechanical-performance foamed bromobutyl rubber composite material according to claim 4, characterized in that: In the step 4, the vulcanization holding time is 450-600s, and the vulcanization pressure is maintained at 10MPa.

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