CN103030895A - High-gas-barrier-property thermoplastic vulcanized rubber and preparation method thereof - Google Patents

Abstract

A high gas barrier thermoplastic vulcanizate and a preparation method thereof belong to the technical field of vulcanizates. Raw material composition: Chlorobutyl rubber 100, nylon 25-66.7, vulcanization aid 0-5, zinc oxide 5, stearic acid 2, plasticizer 0-30, maleic anhydride 10-20, polyisobutylene 5-10 , Antioxidant 1. Put chlorinated butyl rubber, polyisobutylene and maleic anhydride into twin-screw extruder and granulate to prepare "self-made premix"; nylon, antioxidant, zinc oxide, stearic acid, vulcanization aid , plasticizer and "self-made premix" are dynamically cross-linked in a twin-screw extruder; the material is discharged. The vulcanized rubber prepared by the method of the invention has low hardness, high air tightness and excellent physical and mechanical properties.

Description

A kind of high gas barrier thermoplastic vulcanizate and preparation method thereof

technical field

The invention relates to a high gas barrier thermoplastic vulcanizate and a preparation method thereof, in particular to a butyl rubber/nylon thermoplastic vulcanizate and a preparation method thereof, belonging to the technical field of vulcanizate.

Background technique

Dynamic cross-linking technology: Rubber and thermoplastics are mixed under high temperature (slightly greater than the melting point of the plastic phase) and high shear conditions. Due to the presence of vulcanizing agents, the rubber phase will undergo chemical cross-linking, and the cross-linked rubber is mixed at high speed. Under the action of shearing, it is crushed into a large number of micron-sized rubber particles, and finally dispersed in the continuous thermoplastic to form a highly dispersed "sea-island structure" thermoplastic vulcanizate, then the technology for forming this thermoplastic vulcanizate That is the dynamic cross-linking technology. Thermoplastic vulcanizates not only have the excellent properties of traditional cross-linked rubbers, but also have the processing characteristics of thermoplastics. In many fields, thermoplastic vulcanizates are gradually replacing traditional thermosetting rubbers.

The thermoplastic vulcanizate prepared by mixing butyl rubber and nylon and undergoing dynamic cross-linking has good physical and mechanical properties and excellent air tightness, and also has the characteristics of easy processability and repeatability. It is mainly used in tires airtight layer. Compared with the traditional tire inner liner, the tire inner liner prepared by using butyl rubber/nylon dynamic cross-linked thermoplastic vulcanizate has the advantages of light weight and good air tightness. However, for the butyl rubber/nylon system, the two-phase compatibility of rubber and plastic is a key research issue. If the two-phase compatibility of rubber and plastic is poor, it will make it difficult for the crosslinked rubber to be sheared into a uniform and fine dispersed phase. Particles, which ultimately affect the microphase structure of the thermoplastic vulcanizate. Patent US005574105A is a solution to the problem that "poor compatibility of rubber and plastic will be unfavorable to the microscopic phase state and related properties of thermoplastic vulcanizate after dynamic crosslinking". As we all know, nylon 12 is a polar thermoplastic vulcanizate. Plastics, chlorinated butyl rubber is a non-polar saturated rubber, and polypropylene is also non-polar, and the solubility parameters of chlorinated butyl rubber and polypropylene are very close, so chlorinated butyl rubber and polypropylene The thermoplastic elastomer obtained after dynamic cross-linking as the main raw material will not have problems caused by poor compatibility. The final thermoplastic vulcanizate is a kind of polypropylene as the continuous phase and the rubber phase as the dispersed phase. The "sea-island structure", finally in order to solve the problem of poor heat resistance and air tightness of this kind of thermoplastic vulcanizate, it is blended with a certain amount of nylon and maleic anhydride grafted polypropylene to finally obtain a thermoplastic vulcanizate. And good air tightness thermoplastic vulcanizate. Although this preparation method chooses to avoid the problems caused by dynamic vulcanization due to poor compatibility of rubber and plastic, due to the addition of more plastic phases (the ratio of rubber to plastic is close to 1:1), the thermoplastic vulcanizate produced Higher hardness (greater than 40 Shore D).

Then, for a thermoplastic vulcanizate that can be applied to the tire inner liner, it should have the basic characteristics of low hardness, high air tightness, and excellent physical and mechanical properties. As for the chlorinated butyl rubber/nylon 12 system, how to improve the compatibility of the rubber and plastic phases and reduce the hardness of the thermoplastic vulcanizate while maintaining the original physical and mechanical properties and air tightness is the difficulty of research.

Contents of the invention

The main purpose of the present invention is to provide a thermoplastic vulcanizate with high gas barrier performance and a preparation method thereof.

In order to achieve the above object, the technical solution of the present invention is to provide a thermoplastic vulcanizate with high gas barrier performance, which is characterized in that it is made of the following raw materials in parts by mass (phr):

Described nylon is nylon 12; Described vulcanization aid is 1,3-bis citroimide methylbenzene (PK900); Described plasticizer is liquid polyisobutylene (PIB) and N-butyl Benzenesulfonamide (N-BBSA), and the mass ratio of liquid PIB to N-BBSA is between 1.0-4.0, and the antioxidant is hindered phenolic antioxidant, which is antioxidant 1010.

The mass fraction of the above-mentioned plasticizer is preferably greater than zero.

A method for preparing a high gas barrier thermoplastic vulcanizate, characterized in that the preparation steps are as follows:

The first step. Take raw materials by mass parts;

Step 2. Put chlorinated butyl rubber, polyisobutylene and maleic anhydride into twin-screw extruder and granulate to prepare "self-made premix". ℃, the twin-screw speed is 300 rpm;

Step 3. Put nylon, antioxidant, zinc oxide, stearic acid, vulcanization aid, plasticizer and "self-made premix" into the twin-screw extruder for dynamic cross-linking, and the screw temperature is 190-220 ℃, the head temperature is 190 ℃, and the twin-screw speed is 500 rpm;

The fourth step. Discharge.

The above-mentioned "self-made premix" is polyisobutylene and maleic anhydride reacted at high temperature (160-180 ° C), and at the same time through the strong shear of the twin-screw and mixed with chlorinated butyl rubber uniformly to obtain a terminal band Anhydride-reactive mixture.

The present invention proposes three technologies: the one is that N-butylbenzenesulfonamide and liquid polyisobutylene are combined with plasticizing technology. N-butylbenzenesulfonamide is a small molecular liquid with good fluidity. Under high temperature conditions (about 190°C), the amide bond on N-butylbenzenesulfonamide can interact with the amide bond on nylon. The chemical action forms hydrogen bonds, which can destroy the regular structure of nylon itself, reduce the crystallinity of nylon, and finally reduce the hardness of nylon, and because the matrix of the thermoplastic vulcanizate obtained after dynamic crosslinking is nylon, that is, the hardness of the nylon matrix itself is reduced. Very effective on the hardness of thermoplastic vulcanizates. However, N-butylbenzenesulfonamide is a liquid small molecule. If the amount of N-butylbenzenesulfonamide added is too large, the air tightness and physical and mechanical properties of thermoplastic vulcanizates will decline rapidly. Therefore, N-butylbenzenesulfonamide The amount of amide should not be too large. In order to reduce the hardness of thermoplastic vulcanizate, in addition to reducing the hardness of the base nylon, it is also possible to reduce the hardness of the vulcanized rubber. Liquid polyisobutylene is selected to plasticize butyl rubber. Due to the similar structure of liquid polyisobutylene and butyl rubber, liquid Polyisobutylene contains a large number of side methyl groups, therefore, while using liquid polyisobutylene to plasticize vulcanizate, it can also maintain good airtightness to a certain extent. In order to obtain a thermoplastic vulcanizate with low hardness and excellent comprehensive properties, the combination of N-butylbenzenesulfonamide and liquid polyisobutylene is selected. According to the test data, the mass ratio of liquid polyisobutylene to N-butylbenzenesulfonamide is The thermoplastic vulcanizate obtained between 1.0-4.0 has the best overall performance. If the mass ratio of liquid polyisobutylene to N-butylbenzenesulfonamide is greater than 4.0, the amount of liquid polyisobutylene added is too large, and the thermoplastic vulcanizate The physical and mechanical properties are severely reduced; if the mass ratio of liquid polyisobutylene to N-butylbenzenesulfonamide is less than 1.0, the amount of N-butylbenzenesulfonamide added is too large, and the airtightness of thermoplastic vulcanizates will be seriously affected. Influence. The second is the "in-situ volume expansion technology" of "self-made premix". Highly active polyisobutylene reacts with maleic anhydride at high temperature (160-180°C) (it can be used as a solubilizer polyisobutylene succinic anhydride (PIBSA)), and at the same time undergoes strong shearing action of the twin-screw and simultaneously reacts with butyl chloride The base rubber is evenly mixed, and finally a "self-made premix" with anhydride activity in the end group is prepared. The anhydride bond on the premix is very easy to react with the hydrogen bond on the nylon under high temperature conditions, so a "self-made premix" is achieved. In-situ compatibilization” effect, and because polyisobutylene contains more side methyl groups, the “self-made premix” can also maintain the airtightness of the thermoplastic vulcanizate itself while achieving rubber-plastic two-phase compatibilization. , so it is an ideal compatibilizer for this system. The third is dynamic cross-linking technology. Dynamic cross-linking technology is a relatively new technical means. It refers to mixing rubber with thermoplastics under high temperature and high-speed shear conditions, and adding a certain amount of vulcanizing agent to chemically cross-link the rubber phase. Cross-linked rubber Under the action of high-speed mixing and shearing, it is crushed into a large number of micron-sized rubber particles, and finally dispersed in the continuous thermoplastic to form a highly dispersed thermoplastic vulcanizate. Then this technology for preparing thermoplastic vulcanizates is dynamic. Cross-linking technology. Thermoplastic vulcanizates prepared by dynamic cross-linking technology not only have the excellent properties of traditional vulcanized rubber, but also have the processing characteristics of thermoplastics. In many fields, thermoplastic vulcanizates are gradually replacing traditional thermosetting rubber. However, as we all know, dynamic cross-linking technology It is not very suitable for the preparation of low hardness materials. The present invention adopts N-butylbenzenesulfonamide/liquid polyisobutylene plasticization technology, "in-situ compatibilization technology" of "self-made premix" and dynamic crosslinking technology (three technologies are indispensable), and finally prepares A high gas barrier thermoplastic vulcanizate with low hardness, high air tightness and excellent physical and mechanical properties has been produced.

specific implementation plan

Below in conjunction with embodiment, the present invention is described in further detail:

The tensile strength, tear strength and Shore A-type hardness in the examples are measured according to GB/T528-1998, GB/T529-1999 and GB/T6031-1998 respectively; the test conditions for compression set: 100°C×24h, The pre-compression rate is 25%, and the cylindrical shape of φ25mm×12.5mm is measured according to GB/T7759-1996; the air permeability is tested according to the ISO2782 standard with a self-made automatic air tightness tester for gas barrier performance.

comparative example

The preparation method is as follows:

The first step. Weigh 1000 grams of chlorobutyl rubber, 50 grams of high-activity polyisobutylene, and 100 grams of maleic anhydride, put them into twin-screw extruders and granulate, and prepare a "self-made premixed compound" with anhydride activity in the terminal group. Object", screw temperature/°C: 160/170/170/170/180/180/180/180/180/180/180/170, head temperature 160°C, twin-screw speed 300 rpm;

The second step. Weigh 250 grams of nylon, 50 grams of zinc oxide, 20 grams of stearic acid, 10 grams of antioxidant and the "self-made premix" prepared in the first step, and put it into a twin-screw extruder for dynamic crosslinking , Screw temperature/°C: 190/220/220/220/220/220/220/220/220/220/220/220, head temperature is 190°C, twin-screw speed is 500 rpm;

The third step. Discharge. The material properties are shown in Table 1.

Example 1

The preparation method is as follows:

The first step. Weigh 1000 grams of chlorinated butyl rubber, 75 grams of high-activity polyisobutylene, and 150 grams of maleic anhydride, put them into twin-screws, extrude and granulate, and prepare a "self-made premix" with anhydride activity in the terminal group Object", screw temperature/°C: 160/170/170/170/180/180/180/180/180/180/180/170, head temperature 160°C, twin-screw speed 300 rpm;

The second step. Weigh 500 grams of nylon, 50 grams of zinc oxide, 20 grams of stearic acid, 25 grams of vulcanization aids, plasticizers (polyisobutylene 75 grams; N-butylbenzenesulfonamide 75 grams), antioxidants 10 grams and the "self-made premix" prepared in the first step, put into a twin-screw extruder for dynamic crosslinking, screw temperature/°C: 190/220/220/220/220/220/220/220/220/ 220/220/220, head temperature is 190°C, twin-screw speed is 500 rpm;

The third step. Discharge. The material properties are shown in Table 1.

Example 2

The preparation method is as follows:

The first step. Weigh 1000 grams of chlorobutyl rubber, 100 grams of high-activity polyisobutylene, and 200 grams of maleic anhydride, put them into twin-screws, extrude and pelletize, and prepare a "self-made premixed compound" with anhydride activity in the terminal group. Object", screw temperature/°C: 160/170/170/170/180/180/180/180/180/180/180/170, head temperature 160°C, twin-screw speed 300 rpm;

The second step. Weigh 667 grams of nylon, 50 grams of zinc oxide, 20 grams of stearic acid, 50 grams of vulcanization aids, plasticizers (150 grams of polyisobutylene; 150 grams of N-butylbenzenesulfonamide), antioxidant 10 grams and the "self-made premix" prepared in the first step, put into a twin-screw extruder for dynamic crosslinking, screw temperature/°C: 190/220/220/220/220/220/220/220/220/ 220/220/220, head temperature is 190°C, twin-screw speed is 500 rpm;

The third step. Discharge. The material properties are shown in Table 1.

Example 3

The preparation method is as follows:

The first step. Weigh 1000 grams of chlorinated butyl rubber, 75 grams of high-activity polyisobutylene, and 150 grams of maleic anhydride, put them into twin-screws, extrude and granulate, and prepare a "self-made premix" with anhydride activity in the terminal group Object", screw temperature/°C: 160/170/170/170/180/180/180/180/180/180/180/170, head temperature 160°C, twin-screw speed 300 rpm;

The second step. Weigh 500 grams of nylon, 50 grams of zinc oxide, 20 grams of stearic acid, 25 grams of vulcanization aids, plasticizers (100 grams of polyisobutylene; 50 grams of N-butylbenzenesulfonamide), antioxidant 10 grams and the "self-made premix" prepared in the first step, put into a twin-screw extruder for dynamic crosslinking, screw temperature/°C: 190/220/220/220/220/220/220/220/220/ 220/220/220, head temperature is 190°C, twin-screw speed is 500 rpm;

The third step. Discharge. The material properties are shown in Table 1.

Example 4

The preparation method is as follows:

The first step. Weigh 1000 grams of chlorinated butyl rubber, 75 grams of high-activity polyisobutylene, and 150 grams of maleic anhydride, put them into twin-screws, extrude and granulate, and prepare a "self-made premix" with anhydride activity in the terminal group Object", screw temperature/°C: 160/170/170/170/180/180/180/180/180/180/180/170, head temperature 160°C, twin-screw speed 300 rpm;

Step 2. Weigh 500 grams of nylon, 50 grams of zinc oxide, 20 grams of stearic acid, 25 grams of vulcanization additives, plasticizer (120 grams of polyisobutylene; 30 grams of N-butylbenzenesulfonamide), antioxidant 10 grams and the "self-made premix" prepared in the first step, put into a twin-screw extruder for dynamic crosslinking, screw temperature/°C: 190/220/220/220/220/220/220/220/220/ 220/220/220, head temperature is 190°C, twin-screw speed is 500 rpm;

The third step. Discharge. The material properties are shown in Table 1.

Table 1

Claims (7)

1. a high gas-obstructing character thermoplastic sulfurized rubber is characterized in that, comprises that the raw material of following mass fraction (phr) is made:

2. according to a kind of high gas-obstructing character thermoplastic sulfurized rubber of claim 1, it is characterized in that described nylon is nylon 12.

3. according to a kind of high gas-obstructing character thermoplastic sulfurized rubber of claim 1, it is characterized in that described vulcanization aid is the two lemon imide methylbenzene (PK900) of 1,3-; Described softening agent is liquid polyisobutene (PIB) and N-butylbenzenesulfonamide (N-BBSA), and liquid PIB and N-BBSA mass ratio are between 1.0-4.0.

4. according to a kind of high gas-obstructing character thermoplastic sulfurized rubber of claim 1, it is characterized in that described oxidation inhibitor is Hinered phenols antioxidant.

5. according to a kind of high gas-obstructing character thermoplastic sulfurized rubber of claim 1, it is characterized in that described oxidation inhibitor is antioxidant 1010.

6. according to a kind of high gas-obstructing character thermoplastic sulfurized rubber of claim 1, it is characterized in that the mass fraction of above-mentioned softening agent is preferably greater than 0.

7. the method for a kind of high gas-obstructing character thermoplastic sulfurized rubber of preparation claim 1 is characterized in that, may further comprise the steps:

The first step. take by weighing raw material by mass fraction;

Second step. chlorinated butyl rubber, polyisobutene and maleic anhydride are put into twin screw extrude also granulation, prepare " self-control pre-composition ", extruder temperature is 160-180 ℃, and head temperature is 160 ℃, and the twin screw rotating speed is 300 rev/mins;

The 3rd step. nylon, oxidation inhibitor, zinc oxide, stearic acid, vulcanization aid, softening agent and " self-control pre-composition " are put into the twin screw extruder dynamic crosslinking, and extruder temperature is 190-220 ℃, and head temperature is 190 ℃, and the twin screw rotating speed is 500 rev/mins;

The 4th step. discharging.