KR100330366B1 - Rubber curing bladder and air bag composition having improved thermal conduction property and limited life cycle - Google Patents

Abstract

The present invention is to provide a rubber composition for a vulcanizing bladder and airbag.

The present invention relates to a vulcanizing tire of a pneumatic tire in which a rubber compound for a vulcanizing bladder and an air bag of a pneumatic tire is added, in which 1 to 6 parts by weight of zincated and 0.1 to 2 parts by weight of stearic acid are added. It is to provide a rubber composition for ladders and airbags.

The rubber composition for vulcanizing bladder and airbag of the present invention improves scorch stability during processing, and is used as a vulcanization accelerator, activator and processing aid during vulcanization to improve the vulcanization rate, thereby shortening the vulcanization time of the rubber composition and improving the dispersibility of zinc. It is possible to improve the productivity of the vulcanizate through the improvement of the limit life of the vulcanization brader and the airbag of the pneumatic tire and the thermal conductivity by suppressing the occurrence of the breakdown start point due to deterioration and growth of the stress transmission path.

Description

Rubber curing bladder and air bag composition having improved thermal conduction property and limited life cycle

The present invention relates to rubber compositions for vulcanizing bladders and airbags with improved thermal conductivity and limit lifetime. More specifically, the present invention relates to a rubber composition for a vulcanizing bladder and an air bag in which galvanization prepared by a wet chemical reaction as a accelerator and stearic acid as an activator and a processing aid are used as accelerators.

Until now, a vulcanizing brader has been used as a method of vulcanizing pneumatic tires, and in the case of other vulcanizates, vulcanizing airbags have been used.

The conventional problem is that the processability of the rubber composition for the vulcanizing bladder and air bag of the pneumatic tire is poor, and in particular, the poor mixing processability of chloroprene (hereinafter referred to as CR) used as the vulcanizing agent and the vulcanization accelerator (hereinafter referred to as the Soviet Union for improving the dispersion property Dispersion is poor, and it acts as a major cause of deterioration of the physical properties of the finished rubber, life of the vulcanizing bladder and airbag.

In the case of vulcanizing bladders and airbags, due to the harsh conditions of use (for example, high temperature, high pressure, high elongation, dissolved solid oxygen in steam, etc.), they generally have a compounded rubber composition as shown in Table 1 below.

(General Rubber Composition for Vulcanizing Braders and Air Bags) Item Usage (part by weight) Usage Polymer (IIR) 100 Basic Polymer Chloroprene, CR 0-10 Improved vulcanization Carbon black 40 to 60 Improved vulcanization Processing aid 1 to 15 Reinforcement effect Active agent 1 to 5 Improved mixing, extrusion and rolling capacity accelerant 1 to 8 Improved vulcanization Vulcanizing agent 3 to 12

However, the rubber compositions shown in Table 1 have poor processability in the Bambury mixer and extruder in the field, resulting in reduced productivity and increased defects during processing, and significantly lower physical properties due to the low mixing properties of isobutylene isoprene rubber used. Indicates.

The fundamental reason for the occurrence of the above phenomenon is the lack of shear stress during processing of isobutylene isoprene rubber used as the base polymer, poor mixing properties compared to other polymers, poor dispersion of other accelerators and activators, chloroprene rubber used as accelerators This is because wetting is inferior.

The main performances of the vulcanizing bladder and airbag of the conventional pneumatic tire

Performance is characterized by (1) heat transfer capacity, (2) limit life, and much effort has been made to improve them. However, the recent development direction of the technology is changing to the development of technology to reduce the manufacturing defects, such as vulcanization bladder and airbag.

Recently, the use of a high thermal conductivity reinforcing agent and other special compounding agent is increasing to improve the heat transfer capacity, and the thinning of the vulcanization bladder and air bag of the heat transfer medium has been studied and put into practical use at the same time.

In addition, we are trying to solve the stress concentration phenomenon by changing the base polymer to minimize the stress concentration phenomenon that occurs during the use and use of other types of polymers, and by reducing the manufacturing defects by improving the dispersibility of the accelerator. .

However, in order to solve the conflicting factors of improving the thermal conductivity properties and the compounded rubber properties to improve the limit life, various reinforcing agents which are difficult to process are used. Therefore, when considering harsh operating conditions such as a vulcanizing bladder and an airbag, Very limited processing aids have to be used.

Given that base polymers such as vulcanizing bladder and airbags are isobutylene-isoprene inferior to polymers with mixed processability, the use of processing aids is essential, and the use of hydrocarbon oils and oils containing heat resistant materials as processing aids is essential. Doing.

However, zincation (French: indirect KS # 2, US: indirect (AP # 1)) used as an accelerator in the formulation is poor in dispersion during the mixing process. ), Defects in manufacturing are acting as an initial point of failure due to deterioration (e.g. thermal aging, ozone aging, mechanical aging, etc.) under high temperature, high humidity, high elongation conditions, and stress transfer paths ( The weak point is that it can act as a stress propagation path.

In addition, the zincation (French: indirect KS # 2, US: indirect (AP # 1)) is used because of the excessive use due to the low activity, it also acts as another cause of the deterioration of physical properties.

Therefore, the present invention solves the problems of the vulcanizing bladder and the air bag to improve the vulcanization properties (for example, tensile properties and fatigue resistance), vulcanization degree, vulcanizing agent dispersibility, reducing manufacturing defects in terms of compounding rubber composition In terms of the finished product of the vulcanizing bladder and the air bag, it is to provide a new formulation composition that can act as an improvement in productivity through improved thermal conductivity, an initial occurrence point of deterioration through improved degradation of the formulation composition, and a method of inhibiting growth.

Accordingly, an object of the present invention is to provide a rubber composition for vulcanizing braders and airbags, which has improved thermal conductivity and a limited lifetime using stearic acid as an activator and stearic acid as an activator and processing aid.

The present invention for achieving the above object, in the rubber composition for the vulcanizing bladder and air bag of the pneumatic tire, when the rubber compounding is prepared by wet chemical reaction with respect to 100 parts by weight of isobutylene-isoprene rubber 1 To 6 parts by weight and 0.1 to 2 parts by weight of stearic acid, and a rubber composition for a vulcanizing bladder of a pneumatic tire and an air bag. According to the present invention, the galvanizing furnace has a particle surface area measured using a nitrogen gas adsorption method. It is preferable to use galvanization which is at least 6 m 2 / g and produced by a wet chemical reaction in which ZnCO ₃ is made up to 10% or less.

Hereinafter, the present invention will be described in detail.

In the present invention, the zincation is prepared by the following method. That is, in the production of active ZnO, zinc (Zn) is treated with a strong acid such as H ₂ SO ₄ to form a solution, and then Fe is removed by KMnO ₄ , Zinc dust, Na ₂ CO _3, etc. The addition of a basic solution of ZnCO ₃ gives rise to a large surface area as CO ₂ is removed during drying, which is represented by the formula: H ₂ SO ₄ + Zn ⇒ ZnSO ₄ + H ₂ ↑ ZnSO ₄ + Na ₂ CO ₃ ⇒ ZnCO ₃ + Na ₂ SO ₄ ZnCO ₃ ⇒ ZnO + CO _{2 The} surface area is increased during the drying process in which the last step of CO ₂ is removed. On the other hand, since the removal of CO ₂ is difficult, a small amount of ZnCO ₃ remains, and ZnCO ₃ is known to play the same role as ZnO. The present invention is prepared by wet chemical reaction when formulated into a rubber composition for a vulcanizing bladder and an airbag. Zincated and stearic acid were added to give the following effects.

When the rubber for vulcanizing bradder and air bag is mixed, the zincation produced by the wet chemical reaction is used as a vulcanizing agent, and thus the activation is very high, and it is combined with the chloro group of the chloroprene rubber to form a ZnCl group to improve the vulcanizability. In addition, since the zincation produced by the wet chemical reaction used as a vulcanizing agent exhibits excellent dispersibility, the ZnCl group formed with high activity also exhibits excellent dispersibility, thereby improving scorch stability and improving processability.

It also improves vulcanization properties (e.g., tensile properties, fatigue resistance, etc.), improves vulcanization, improves dispersibility of vulcanizing agents, and improves lifespan. Improved productivity through improved thermal conductivity, suppressed the initial occurrence and growth of degradation of the vulcanizing bladder and airbag through improved degradation of the formulation composition to improve the life of the limit.

Examples 1 to 10

The rubber compounding composition was prepared according to the composition and composition ratio as shown in Table 2 below, and the physical properties of these compounding compositions are shown in Table 3 below.

(Rubber compounding composition) Example One 2 3 4 5 6 7 8 9 10 Isobutylene-Isoprene Rubber 100 100 100 100 100 100 100 100 100 100 Chlorprene 6 6 6 6 6 6 6 6 6 6 Carbon black 60 60 60 60 60 60 60 60 60 60 oil 6 6 6 6 6 6 6 6 6 6 ZnO-I 4 3 ZnO-II One 4 6 8 4 4 4 ZnO-III 4 ZnO-IV 4 Stearic acid 0.2 0.2 0.3 0.1 0.2 0.3 0.3 0.8 2.0 3.0 Vulcanizing agent 12 12 12 12 12 12 12 12 12 12

(1) ZnO-I: ZnO manufactured by dry method [direct method (American), indirect method (French)]

(2) ZnO-II: ZnO prepared by a wet method (surface area of 6 m 2 / g or more, ZnCO ₃ : 10% or less)

(3) ZnO-III: ZnO prepared by a wet method (surface area of 5 m 2 / g or less, ZnCO ₃ : 10% or less)

(4) ZnO-IV: ZnO prepared by a wet method (surface area of 5 m 2 / g or less, ZnCO ₃ : 11% or less)

(Results of physical properties of the compound) Example One 2 3 4 5 6 7 8 9 10 Rheometer + 5 minutes 44 47 50 48 40 46 37 48 47 42 Rheometer + 90 33 32 24 23 19 30 31 28 27 37 The tensile strength Hardness (Shore A) 64 64 64 66 67 62 61 63 63 58 M300 (㎏ / ㎠) 53 55 57 59 60 51 50 56 55 49 Cutting strength (㎏ / ㎠) 120 128 132 140 121 118 117 129 126 115 Cutting strength retention rate (%) 73 79 80 85 68 70 71 73 73 54 Elongation at break (%) 690 710 720 690 640 660 650 710 700 620 Tear strength (㎏ / ㎠) 48 50 53 51 46 46 45 51 50 35 Breaking energy (kgf.㎠) 449 520 525 510 432 440 450 593 510 392 Thermal conductivity 3.51 3.42 3.12 3.19 3.16 5.52 3.54 3.13 3.12 0.31 Vulcanization Brader Limit Life (%) 100 117 160 150 85 98 97 115 104 86 Vulcanizing Agent Dispersibility (%) 100 140 160 150 100 98 96 138 145 128 Permanent deformation (%) 13.7 13.1 12.5 12.3 11.8 14 14.1 13.2 13.6 14.8 Compressive strain (%) 49 41 37 35 41 50 52 42 41 51

(1) Rheometer + 5 minutes measurement temperature: 125 ℃

(2) Rheometer + 90 minutes measuring temperature: 185 ℃

(3) Tensile test condition: Equipment used (Instron), Cross head speed (500 mm / MIN).

Measured by ASTM D3188-91 and D412-92, Curing conditions: 186 × 40 minutes.

(4) Cutting strength retention rate (%): 100 × (cutting strength before aging-cutting strength after aging) / cutting strength before aging,

Aging condition: 100 ℃ × 48 hours

(5) The unit of thermal conductivity measured by the thermal conductivity meter is Kcal / m.hr. ℃ × 10 ^-1

(6) Limit life and vulcanizing agent dispersibility of the vulcanizing bladder are shown as relative values when the comparative example 1 is 100

Comparing Examples 1, 2, 3, and 4, when using zinc oxide prepared by wet chemical reaction from 1 part by weight to 6 parts by weight (PHR), tensile properties (M300, cutting strength, cutting strength retention, cutting elongation) , Breaking energy, tear strength, etc.), thermal conductivity, permanent deformation, and compression deformation performance is improved to improve the life span of the finished product. However, comparing Examples 1 and 5 shows that 8 parts by weight of zinc produced by the wet chemical reaction, rather, the physical properties are lowered, and the limit life is drastically lowered, and the appropriate amount of zincation prepared by the wet chemical reaction is used. It can be seen that 1 to 6 parts by weight.

In addition, the results of testing the physical properties change according to the ZnO-II, ZnO-III, ZnO-IV zincation properties (surface area ZnCO ₃ content measured using nitrogen gas) in the galvanization prepared by wet chemical reaction (Examples 3 and 6) , 7) It can be seen that the physical properties, thermal conductivity, and limit life of the rubber composition are influenced by the surface area and ZnCO ₃ content of zincation prepared by wet chemical reaction.

Comparing Examples 3 and 6, it was found that the tensile properties and the limit lifespan were decreased when the surface area of the zincation prepared by the wet chemical reaction was 6 m 2 / g or less, and when comparing the Examples 3 and 7, the wet chemical reaction When the ZnCO ₃ content contained in the galvanization was 11% or more, the tensile properties and the marginal life were poor.

When 0.1 to 2 parts by weight of stearic acid is used to improve the vulcanizability, the vulcanization properties, and the processability of the rubber composition using galvanization prepared by wet chemical reaction, the galvanization and stearic acid with increased activity are increased. It can be seen that the effect of improving the scorch stability and dispersibility at the time of compounding can greatly reduce manufacturing defects, and improve the limit life.

Comparing Examples 1, 8, and 9, it can be seen that the use of 0.1 parts by weight to 2 parts by weight of stearic acid and 4 parts by weight of galvanized zinc prepared by a wet chemical reaction improves the vulcanizability and the workability. In comparison, when stearic acid is used excessively 3 parts by weight or more, the workability is improved, but the tensile properties and the marginal life is poor.

Claims (2)

In the rubber composition for the vulcanizing bladder and air bag of a pneumatic tire, 1 to 6 parts by weight of zinc prepared by a wet chemical reaction and 0.1 to 2 parts by weight of stearic acid based on 100 parts by weight of isobutylene-isoprene rubber when rubber is mixed. A rubber composition for a vulcanizing bladder and airbag of a pneumatic tire, which is added. The method according to claim 1, wherein the zincation furnace has a particle surface area of 6 m 2 / g or more measured using a nitrogen gas adsorption method, and ZnCO ₃ is prepared using a galvanization prepared by a wet chemical reaction of 10% or less A rubber composition for a vulcanizing bladder and an airbag of a pneumatic tire.