阅读说明：本技术 一种纳米硒导热绝缘橡胶材料及其制备方法和应用 (Nano-selenium heat-conducting and insulating rubber material and preparation method and application thereof ) 是由 朱立新 余翀 吴良辉 侯玙杰 石川 于 2019-10-30 设计创作，主要内容包括：本发明属于天然橡胶材料技术领域,特别涉及一种纳米硒导热绝缘橡胶材料及其制备方法和应用。所述纳米硒导热绝缘橡胶材料由包含由包括以下质量份的组分制成：天然橡胶100份,主促进剂0.5～3份,副促进剂0.5～3份,纳米硒0.5～5份,硫磺0.5～3份,其他助剂1～5份。本发明通过在使用硒代替含锌化合物活化天然橡胶硫化体系并参与天然橡胶交联,形成硒、硫复合交联网络。避免天然橡胶通用活化体系中锌逸散造成的环境污染,同时提升了天然橡胶的导热、绝缘以及物理机械性能。本发明利用点状、线状纳米硒不同的微观结构分别形成了点状和线网状交联结构,其中点状交联结构大幅度提升了天然橡胶的导热、绝缘性能。(The invention belongs to the technical field of natural rubber materials, and particularly relates to a nano-selenium heat-conducting and insulating rubber material as well as a preparation method and application thereof. The nano-selenium heat-conducting insulating rubber material is prepared from the following components in parts by mass: 100 parts of natural rubber, 0.5-3 parts of a main accelerant, 0.5-3 parts of an auxiliary accelerant, 0.5-5 parts of nano selenium, 0.5-3 parts of sulfur and 1-5 parts of other auxiliary agents. The selenium is used for replacing a zinc-containing compound to activate a natural rubber vulcanization system and participate in the crosslinking of natural rubber, so that a selenium-sulfur composite crosslinking network is formed. The environmental pollution caused by zinc dissipation in a general activation system of the natural rubber is avoided, and the heat conduction, the insulation and the physical and mechanical properties of the natural rubber are improved. The invention utilizes different microstructures of the dotted nano selenium and the linear nano selenium to respectively form a dotted cross-linking structure and a wire-mesh cross-linking structure, wherein the dotted cross-linking structure greatly improves the heat conduction and insulation performance of the natural rubber.)

1. The nano-selenium heat-conducting insulating rubber material is characterized by being prepared from the following components in parts by mass: 100 parts of natural rubber, 0.5-3 parts of a main accelerant, 0.5-3 parts of an auxiliary accelerant, 0.5-5 parts of nano selenium, 0.5-3 parts of sulfur and 1-5 parts of other auxiliary agents.

2. The nano-selenium heat-conducting and insulating rubber material as claimed in claim 1, wherein the nano-selenium heat-conducting and insulating rubber material is prepared from the following components in parts by mass: 100 parts of natural rubber, 2 parts of a main accelerant, 2 parts of an auxiliary accelerant, 1 part of other auxiliary agents, 1-2 parts of nano selenium and 1 part of sulfur.

3. The nano-selenium heat-conducting and insulating rubber material as claimed in claim 1 or 2, wherein the nano-selenium is one or both of point-like nano-selenium and linear nano-selenium; the particle size of the sulfur is 100-400 meshes.

4. The nano-selenium heat-conducting and insulating rubber material as claimed in claim 3, wherein the average particle size of the dotted nano-selenium is 50 ± 10 nm; the average diameter of the linear nano selenium is 70 +/-30 nm, and the average length of the linear nano selenium is 5 +/-2 mu m.

5. The nano-selenium heat-conducting and insulating rubber material as claimed in claim 1 or 2, wherein the main accelerator is one or more of zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc ethylphenyldithiocarbamate and tellurium diethyldithiocarbamate.

6. The nano-selenium heat-conducting and insulating rubber material as claimed in claim 5, wherein the secondary accelerator is one or more of 2-mercaptobenzothiazole, dibenzothiazyl disulfide and 2- (2, 4-dinitrophenylthio) benzothiazole; the other auxiliary agents are one or more than two of an anti-aging agent, an anti-scorching agent, a flame retardant and an anti-reversion agent.

7. The preparation method of the nano-selenium heat-conducting and insulating rubber material as claimed in any one of claims 1 to 6, characterized by comprising the following steps:

(1) weighing 100 parts of natural rubber, 0.5-3 parts of a main accelerant, 0.5-3 parts of an auxiliary accelerant, 1-5 parts of other auxiliary agents, 0.5-5 parts of nano selenium and 0.5-3 parts of sulfur in parts by mass;

(2) mixing the nano-selenium and natural rubber in the step (1) to obtain selenium-containing natural rubber, adding the raw materials weighed in the step (1) and the selenium-containing natural rubber into an internal mixer for mixing, after the materials are added, thinly passing through sheets, packaging in a triangular bag, and discharging the sheets to obtain the nano-selenium heat-conducting insulating rubber material.

8. The method for preparing nano-selenium heat-conducting insulating rubber material as claimed in claim 7, wherein the nano-selenium and natural rubber in the step (2) are mixed in a manner that nano-selenium dispersion liquid and natural rubber latex are fully stirred and mixed, and then co-coagulation and precipitation are carried out to obtain solid selenium-containing natural rubber, or solid nano-selenium powder and solid natural rubber are mechanically mixed by an internal mixer and an open mill; and (3) the roll temperature of the mixing in the step (2) is 50 ℃, and the mixing time is 2-5 min.

9. The preparation method of the nano-selenium heat-conducting and insulating rubber material as claimed in claim 8, wherein the concentration of the nano-selenium dispersion liquid is 1-3 mg/mL.

10. The use of the nano-selenium heat-conducting insulating rubber material as claimed in any one of claims 1 to 6 in the field of insulating rubber products.

Technical Field

The invention belongs to the technical field of natural rubber materials, and particularly relates to a nano-selenium heat-conducting and insulating rubber material as well as a preparation method and application thereof.

Background

Natural rubber (natural rubber) is a natural polymer compound containing cis-1, 4-polyisoprene as a main component, and 91-94% of the natural rubber compound is rubber hydrocarbon (cis-1, 4-polyisoprene). The natural rubber mainly contains rubber hydrocarbon, also contains a small amount of protein, moisture, resin acid, saccharides, inorganic salt and the like, has high elasticity, high tensile strength, excellent tear resistance and electrical insulation, good wear resistance and drought resistance and good processability, and is often used as an electrical insulator for insulating gloves, insulating carpets, insulating sheets of touch switches of electric appliances, high-voltage line insulators, damping insulating pads on automobiles, insulating sheaths of wires and cables, various insulating rubber fittings used in national defense and military industry and the like for labor protection. In addition, natural rubber is easy to adhere to other materials and is superior to most synthetic rubbers in comprehensive performance.

The vulcanized natural rubber is in a cross-linked network structure, free electrons of the vulcanized natural rubber are difficult to overflow, the vulcanized natural rubber has good insulating property, but the lack of the free electrons also causes poor heat conduction property of the vulcanized natural rubber, and the heat loss and the heat aging of the natural rubber are often caused by the heat accumulation in the actual use process, so that the physical and mechanical properties and the service life of the natural rubber are influenced. At present, the method for improving the thermal conductivity of natural rubber is to mix thermal conductive fillers such as alumina and boron nitride to form a thermal conductive network in a natural rubber cross-linked network, but the formation of the thermal conductive network is beneficial to the dissipation of free electrons, which often results in the deterioration of the insulation performance and the mechanical performance of the natural rubber. The existing natural rubber materials are generally difficult to simultaneously maintain the heat-conducting property, the insulating property and the mechanical property.

In a natural rubber vulcanization system, zinc oxide is an important vulcanization activator, and the zinc oxide mainly has the effects of activating the vulcanization system, improving the crosslinking density of rubber materials and improving the aging resistance of vulcanized rubber. However, the utilization rate of zinc oxide in a natural rubber vulcanization system is low, the addition amount of zinc oxide in the existing natural rubber formula is generally 5% of the total amount of rubber materials, and the addition of high-dosage zinc oxide causes that a large amount of zinc can be scattered into the environment through abrasion in the use process of a natural rubber product, so that the natural rubber product causes harm to microorganisms and aquatic organisms. The existing improved methods are to manufacture nano zinc oxide, replace zinc oxide with other metal oxides and use functional zinc salt to reduce zinc content, but the existing methods have higher cost and do not completely solve the problem of zinc pollution.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention mainly aims to provide a nano-selenium heat-conducting insulating rubber material.

The invention also aims to provide a preparation method of the nano-selenium heat-conducting and insulating rubber material.

The invention further aims to provide application of the nano-selenium heat-conducting insulating rubber material in the field of preparation of insulating rubber fittings.

The purpose of the invention is realized by the following scheme:

a nano-selenium heat-conducting insulating rubber material is prepared from the following components in parts by mass: 100 parts of natural rubber, 0.5-3 parts of main accelerant, 0.5-3 parts of auxiliary accelerant, 0.5-5 parts of nano selenium, 0.5-3 parts of sulfur and 1-5 parts of other auxiliary agents.

Preferably, the nano-selenium heat-conducting and insulating rubber material is prepared from the following components in parts by mass: 100 parts of natural rubber, 2 parts of a main accelerant, 2 parts of an auxiliary accelerant, 1 part of other auxiliary agents, 1-2 parts of nano selenium and 1 part of sulfur.

Preferably, the natural rubber is Thailand TVR LATEX natural LATEX with a solid content of 30%.

Preferably, the primary accelerator is one or more of zinc diethyldithiocarbamate (EZ), zinc dibutyldithiocarbamate (BZ), zinc ethylphenyldithiocarbamate (PX), and Tellurium Diethyldithiocarbamate (TDEC), and more preferably tellurium diethyldithiocarbamate.

Preferably, the secondary accelerator is one or more of 2-mercaptobenzothiazole (M), dibenzothiazyl Disulfide (DM) and 2- (2, 4-Dinitrophenylthio) Benzothiazole (DBM), and more preferably dibenzothiazyl disulfide.

Preferably, the other auxiliary agents are one or more than two of an anti-aging agent, an anti-scorching agent, a flame retardant and an anti-reversion agent.

Preferably, the nano selenium is one or two of point nano selenium and linear nano selenium.

Preferably, the purity of the sulfur is not lower than 95%, and the particle size of the sulfur is 100-400 meshes.

Preferably, the average particle size of the dotted nano selenium is (50 +/-10) nm, the average diameter of the linear nano selenium is (70 +/-30) nm, and the average length of the linear nano selenium is (5 +/-2) mu m.

The preparation method of the nano-selenium heat-conducting insulating rubber material comprises the following steps:

(1) weighing 100 parts of natural rubber, 0.5-3 parts of a main accelerant, 0.5-3 parts of an auxiliary accelerant, 1-5 parts of other auxiliary agents, 0.5-5 parts of nano selenium and 0.5-3 parts of sulfur in parts by mass;

(2) mixing the nano-selenium and natural rubber in the step (1) to obtain selenium-containing natural rubber, adding the raw materials weighed in the step (1) and the selenium-containing natural rubber into an internal mixer for mixing, after the materials are added, thinly discharging sheets, packaging in a triangular bag, and discharging the sheets to obtain the nano-selenium heat-conducting insulating rubber material.

Preferably, the nano-selenium and natural rubber in the step (2) are mixed in a manner that the nano-selenium dispersion liquid and natural rubber latex are fully stirred and mixed, and then a selenium-containing natural rubber solid is obtained through co-coagulation and precipitation, or solid nano-selenium powder and solid natural rubber are mechanically mixed through an internal mixer and an open mill.

Preferably, the concentration of the nano selenium dispersion liquid is 1-3 mg/mL.

Preferably, the roll temperature of the mixing is 50 ℃, and the mixing time is 2-5 min.

The nano-selenium heat-conducting insulating rubber material is applied to the field of insulating rubber products.

The basic principle of the invention is as follows:

the necklace-shaped soft substance cluster structure formed by sodium dodecyl sulfate-polyethylene glycol (SDS-PEG) can be used as a binary soft template for reducing the nano-element selenium by ascorbic acid, and the water-soluble point-shaped nano-element selenium and the linear nano-element selenium are prepared by changing reaction conditions and a nano-structure growth environment and through the solid-liquid-solid phase transfer characteristic of selenium. The dotted nano selenium is dispersed in the natural rubber matrix more uniformly and has smaller size, and a more compact cross-linked structure and a heat-conducting network can be formed to improve the insulating property and the heat-conducting property of the natural rubber matrix. The linear nano selenium forms a wire-shaped cross-linked structure in the natural rubber matrix, the nano wires and the natural rubber chain segments are mutually entangled to form a cross-linked network in a covalent bond mode, and the cross-linked network improves the insulating property and the heat conducting property of the rubber matrix and enables the vulcanized rubber to generate a stress orientation effect to a certain degree in an external force process, thereby endowing the natural rubber material with excellent physical and mechanical properties.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the selenium is used for replacing an activation system of zinc oxide and stearic acid, so that the effect of a vulcanizing activator is achieved, the activation effect is good, and the pollution to the environment after the zinc escapes can be avoided.

(2) The nano-element selenium obtained by the method has smaller size than micro-selenium, can obtain higher activation effect and crosslinking efficiency after being introduced into natural rubber, and keeps excellent heat-conducting property, insulating property and physical and mechanical properties of the natural rubber.

(3) The punctiform nano-element selenium obtained by the method can form a more compact punctiform cross-linked structure and a heat-conducting network in natural rubber, and improves the insulating property and the heat-conducting property while keeping the high physical and mechanical properties.

(4) The linear nano-element selenium obtained by the method can form a wire-mesh cross-linked structure in natural rubber, and generates a certain degree of orientation effect in the stress process, thereby improving the physical and mechanical properties.

Drawings

FIG. 1 shows a reaction formula of a selenium-sulfur composite system participating in activating an accelerator and crosslinking in the selenium heat-conducting insulating natural rubber.

Fig. 2 is a schematic diagram of the cross-linked network structure of the micro selenium-sulfur composite system of comparative example 1.

Fig. 3 is a schematic view of the cross-linked network structure of the dotted nano-element selenium-sulfur composite system of example 3.

Fig. 4 is a schematic view of the cross-linked network structure of the linear nano-element selenium-sulfur composite system of example 6.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.

The reagents used in the following examples are conventionally available from the market unless otherwise specified.

Tensile strength was determined according to GB/T528-1998.

Thermal conductivity was determined according to GB/T11205-2009.

The dielectric constant was measured according to GB/T1693-2007.

Differential scanning calorimetry analysis A DSC tester, model Discovery DSC 25, from TA, USA was used for the test analysis.

The vulcanization activation energy Ea was calculated by the Ozawa method from DSC measurement data.

The preparation method of the punctiform nano-element selenium comprises the following steps:

(1) selenium dioxide is dissolved in water to prepare a solution a with the concentration of 20 mmol/L; dissolving Sodium Dodecyl Sulfate (SDS) in water to prepare a solution b with the concentration of 10 mmol/L; dissolving polyethylene glycol (PEG) in water to prepare a solution c with the concentration of 20 g/L; dissolving ascorbic acid in water to prepare a solution d with the concentration of 100 mmol/L;

(2) at a fixed volume ratio V_a:V_b:V_cTaking the solution a, the solution b and the solution c in a ratio of 1:1:1, and fully stirring and mixing to obtain a solution e. Keeping the temperature of the solution e and the solution d at 70 ℃ for 20 h;

(3) at a fixed solute mass ratio m_{Ascorbic acid}：m_{Selenium dioxide}Mixing the solution d and the solution e under stirring at a ratio of 15:1, and reacting at 70 ℃ for 5h to obtain an aqueous solution f of amorphous nano red selenium;

(4) and (4) centrifuging and washing the solution f for multiple times at 10000r/min, and dissolving the solution f by using ethanol to obtain an ethanol solution g of amorphous nano red selenium, wherein the molar concentration of the selenium is 5 mmol/L.

(5) Carrying out ultrasonic treatment on the solution g at 70 ℃ and 40kHz for 0.5h to obtain a solution h;

(6) and (4) centrifugally washing the solution h to obtain the punctate nano element selenium.

The preparation method of the linear nano-element selenium comprises the following steps:

(1) selenium dioxide is dissolved in ethanol to prepare a solution a with the concentration of 20 mmol/L; dissolving Sodium Dodecyl Sulfate (SDS) in ethanol to prepare a solution b with the concentration of 10 mmol/L; dissolving polyethylene glycol (PEG) in ethanol to prepare a solution c with the concentration of 20 g/L; dissolving ascorbic acid in ethanol to prepare a solution d with the concentration of 100 mmol/L;

(2) at a fixed volume ratio V_a:V_b:V_cTaking the solution a, the solution b and the solution c in a ratio of 1:1:1, and fully stirring and mixing to obtain a solution e. Keeping the temperature of the solution e and the solution d at 70 ℃ for 20 h;

(3) at a fixed solute mass ratio m_{Ascorbic acid}：m_{Selenium dioxide}Mixing the solution d and the solution e under stirring at a ratio of 15:1, and reacting at 70 ℃ for 5 hours to obtain an ethanol solution f of the linear nano-element selenium;

(4) and centrifugally washing for many times at the rotating speed of 8000r/min to obtain the linear nano-element selenium.