KR101248070B1 - Method of preparing rubber composition for curing bladder - Google Patents

Abstract

PURPOSE: A manufacturing method for a rubber composition for vulcanizing a bladder is provided to reduce the vulcanizing process time, to have excellent processability and workability, and to provide a rubber composition for vulcanizing a bladder with an improved lifetime. CONSTITUTION: A manufacturing method for a rubber composition for vulcanizing a bladder using a 3-batch type mixing method comprises: a step of masticating a rubber polymer, processing aid, general filler, and oil in order; a step of cleaning the finely dispersed filler and adding a thermal conductive additive; a step of mixing 1/2 of a first master batch, neoprene, and a residual first master batch in order; and a step of mixing 1/2 of a second master batch, resin, ZnO, and 1/2 of a second master batch in order.

Description

Manufacturing method of rubber composition for vulcanizing bladder {METHOD OF PREPARING RUBBER COMPOSITION FOR CURING BLADDER}

The present invention relates to a process for the preparation of a rubber composition for a curing bladder that significantly improves the thermal conductivity by mixing high crystalline micrographite as a reinforcing filler with a general filler.

Vortex bladder is commonly used in vulcanization processes for heat transfer and determination of tire internal morphology. Such vulcanization bladder is used as a medium for supplying a heat source, where excellent thermal conductivity is required to improve productivity through shortening of vulcanization time.

Conventional vulcanization bladder compositions are prepared by adding fillers to the raw rubber to withstand steam or hot water, and recently, various additives have been used to improve the thermal conductivity of vulcanization bladder, thereby increasing productivity. This is improving. However, rubber itself has a very low thermal conductivity, there is a problem that the compounding processability with the filler having a high thermal conductivity is lowered, causing the physical properties of the final product.

In order to improve the thermal conductivity, as disclosed in Korean Patent Application No. 1999-20743 (June 4, 1999), Ketjen Black may be mixed with a general filler, but the hardness and tensile strength of rubber The strength is too high and the elongation is too low to perform the role of bladder as well as the fatigue, the price increase, and the difficulty of dispersion. In addition, if the hardness of the rubber composition is too high, it is difficult to attach to a cure press, which has the disadvantage of lowering workability.

In addition, as disclosed in Korean Patent Application No. 1997-40146 (August 22, 1997), when graphite having excellent thermal conductivity is used in combination with a general filler, for example, when 5 to 10 parts by weight is used, substantially thermal conductivity In addition, the effect of improving the degree is not so great, and when exceeding the amount in the above range, when mixed with a general filler, it may cause a decrease in the fairness and a decrease in the physical / chemical properties due to non-dispersion. .

In addition, the raw material rubber of the rubber compound for bladder is mainly used butyl rubber excellent in heat resistance, aging resistance and air permeability, and in order to improve the thermal conductivity characteristics during vulcanization of the tire, it has excellent thermal conductivity characteristics and molecular surface area as a filler. Large and well-developed furnace carbon black N220 (C / B grade) or N330 (C / B grade) is used. In order to improve the tire productivity, many measures have been taken to reduce the cure time of the tire, and the method of maintaining the vulcanization temperature of the tire at a high temperature of 180 ° C. or higher, or carbon black having excellent thermal conductivity as a filler The method to use is used. However, increasing the amount of N330 or N220 furnace carbon black may increase the thermal conductivity, but there is a limit to increasing the amount of carbon black used due to dispersion and excessive heat generation. In addition, acetylene black, which has better thermal conductivity than N330 or N220, is used in combination with carbon black, but there are some problems. The main problem is that in order to maintain good thermal conductivity properties, acetylene black should be used at least 25 parts by weight per 100 parts by weight of raw rubber. However, in this case, since the cure rate is lowered and the degree of rubber binding is lower than that of carbon black, the molecular chain is subjected to deformation under high temperature conditions of 185 ° C or higher. The relaxation phenomenon of) increases significantly, and butyl rubber, which is a raw rubber, also causes a decrease in physical properties due to a decrease in heat resistance and aging resistance under high temperature and high pressure steam.

Adding a thermally conductive additive to a rubber composition including a general filler improves the thermal conductivity of the vulcanizing bladder to facilitate heat transfer with the tire, but it is difficult to mix due to the poor bonding strength of the rubber with the thermally conductive additive. In particular, highly crystalline micrographite can inhibit its unique lubricity and binding to other additives because it lacks molecular chains that can bind rubber.

Republic of Korea Patent Application No. 1999-20743 (June 4, 1999) Republic of Korea Patent Application No. 1997-40146 (August 22, 1997) Republic of Korea Patent No. 10-0837081

Accordingly, the present invention is to solve the above problems, an object of the present invention is to provide a method for producing a vulcanization bladder applied to the general filler and high crystalline micrographite used in the rubber composition, using a thermally conductive filler Even if it is to provide a rubber composition for vulcanizing bladder with improved thermal conductivity while maintaining the physical / chemical properties level of the rubber composition.

In addition, the present invention facilitates the construction of a conducting pathway using a high crystallinity micrographite specially selected to have a high crystallinity and a plate-like structure, unlike the general filler, the vulcanization process through rapid heat transfer of the rubber composition for vulcanizing bladder You can expect a reduction in time.

Therefore, in order to realize the above object, the rubber composition for vulcanizing bladder for improving the thermal conductivity according to the present invention, the fossil containing graphite is collected, separated and purified, or calcined at 2000 ℃ or more In this case, the crystallinity (Lc) is 30 nm to 300 nm or more, the purity is 80% to 99%, and the thermal conductivity of the additive (high-crystalline micrographite) itself is 100W / mK to 200W / mK (meter-Kelvin). High crystalline micrographite is used as filler; 10 to 60 parts by weight of general filler, based on 65 to 100 parts by weight of butyl rubber and 100 parts by weight of the raw material rubber mixed with 0 to 35 parts by weight of a resinous vulcanization additive such as neoprene; 20 to 60 parts by weight of the high crystalline micrographite; 3 to 15 parts by weight of an alkyl phenol vulcanization resin; 0-20 parts by weight of castor oil; And 3 to 10 parts by weight of zinc oxide for resin crosslinking.

In addition, the manufacturing method of the rubber composition for vulcanizing bladder for improving the life, the rubber polymer is used in the order of mastication, processing aids, general fillers and oils, while cleaning the undispersed fillers, A first step of adding a thermally conductive additive (highly crystalline micrographite, an acetylene block) between them ; A second process of mixing in order of first master batch 1/2, neoprene and first master batch 1/2; And a third process of mixing in order of the second master batch 1/2, the resin, ZnO and the second master batch 1/2 from the second process. Here, the master batch means a compound rubber formed by dispersing the raw material rubber and additives.

Fillers used to improve the thermal conductivity of the present invention, when the fossil containing graphite is collected, separated and purified, or calcined at 2000 ℃ or more, the crystallinity (Lc) of the filler is 30nm to 300nm or its High crystalline micrographite having a purity of 80% to 99% and the thermal conductivity of the additive itself is 100W / mK to 200W / mK.

According to the present invention for achieving the above object, the processability of the compounding is improved, the thermal conductivity characteristics are improved, and the specific effects such as shortening of the vulcanization time can be exhibited.

The rubber composition for vulcanizing bladder may include 10 to 60 parts by weight of a general filler based on 65 to 100 parts by weight of butyl rubber and 100 parts by weight of raw rubber mixed with 0 to 35 parts by weight of neoprene as a resin vulcanization additive; 20 to 60 parts by weight of high crystalline micrographite; 3 to 15 parts by weight of an alkylphenol vulcanized resin; 0 to 20 parts by weight of castor oil; And 3 to 10 parts by weight of zinc oxide for resin crosslinking.

Herein, the term "general filler" refers to a filler used for raw rubber such as general-purpose carbon black and silica, and in general, it is preferable to use a furnace black (Furnace Black) as the rubber composition for vulcanizing bladder.

According to the present invention, when compared with the prior art using ordinary fillers and thermally conductive fillers, it is possible to smoothly blend the process without lowering the physical properties of the rubber composition, thereby increasing the work processability and significantly improving the thermal conductivity to vulcanize. Rubber compositions have been obtained that can shorten process time and extend life.

Hereinafter, the present invention will be described in more detail through the following Preparation Examples, Comparative Examples, Examples and Test Examples. However, these do not limit the technical scope of the present invention.

<Production Example> Mixing method of thermally conductive filler

In general, when preparing a rubber composition, using the prior art mixing method, the bonding strength between the thermally conductive filler and the rubber is reduced, which leads to difficulty in dispersion.

There is no problem of mixing even if the 3-batch mixing method described in Korean Patent No. 10-0837081 is used, but if the product is manufactured and then used in practice, it is bladder due to bubbles generated in the product. There is a problem that the life of the shortening.

Therefore, the mixing method of the three-batch mixing method was applied by further changing and applying the mixing method of the prior art mixing method of the order of general master batch and final batch.

In the first process, after the rubber polymer is soaked for 30 to 50 seconds or more, the processing aid, the general filler of the furnace black system and the oil are sequentially added, and then blended to prevent agglomeration of the rubber inside the blender. to raising the ram (ram) of the blender in the step for cleaning to be adjusted so that the rubber compound which stick together inside the mixer may be well blended for about 8 seconds to about 20 seconds, at this time if the cleaning time exceeds 20 seconds, The scattering of fillers can lead to different physical properties. At the time of cleaning, the thermally conductive additive is added and mixed under conditions of 40 to 60 rpm and 40 to 60 ° C. temperature control unit (TCU) temperature.

In basic formulations, it is common to add materials that are difficult to disperse, but thermally conductive additives, especially high crystalline micrographite, have little molecular chains that can chemically bond with the compounding rubber and due to their inherent lubricity, May inhibit the binding force of the. As the bladder is used under high temperature and high pressure conditions, there is a fear that the bonding force may decrease during use, and thus the life may be shortened depending on the compounding method. On the other hand, first, a general filler, which constrains product life and physical properties, is added to disperse well with the rubber compound, and then, the relatively low-bonding high-crystalline micrographite is added and mixed only to a level capable of physically bonding to the desired thermal conductivity. To achieve the degree.

In the second process, the first master batch 1/2, the neoprene and the first master batch 1/2 corresponding to half (1/2) of the first master batch for the dispersibility of the neoprene are added in order to 40 to 60 rpm And under conditions of 40 to 60 ° C. TCU temperature.

In a third process, the second master batch 1/2, the resin, ZnO and the second master batch 1/2 from the second process are subjected to 40-50 rpm and 40-60 ° C. TCU temperatures to aid in dispersion of the resin. Mix.

In addition, a thermally conductive additive can be added in a 1st process and a 2nd process as needed.

<Comparative Examples 1 and 2>

As illustrated in Table 1 below, Comparative Example 1 is a prior art compounding method consisting only of a master batch and a final batch, and Comparative Example 2 is a first process of sequentially adding a rubber polymer, a processing aid, a thermal conductive additive and an oil , A second step of mixing the first master batch and neoprene, and then adding the second filler in the order of the general filler, and a third step of mixing the second master batch 1/2 from the second step, resin and ZnO in this order. It was prepared in a three-batch mixing mode.

&Lt; Example 1 >

Example 1 is a method of solubilizing a rubber polymer, adding processing aids, general fillers and oils in order, cleaning undispersed fillers, and adding a thermally conductive additive therebetween. First process; A second process of mixing the first master batch 1/2, the neoprene and the first master batch 1/2 in order; And a third process of sequentially mixing the second master batch 1/2, the resin, ZnO and the second master batch 1/2 from the second process.

Amount of ingredient in weight parts ingredient Comparative Example 1 Comparative Example 2 Example 1 Butyl rubber 95 95 95 Neoprene 5 5 5 Furnace black (n220) 60 30 40 High Crystalline Fine Graphite 30 30 30 Resin 8 8 8 Zinc oxide 5 5 5 Caster oil 6 6 6

&Lt; Test Example 1 >

Each rubber composition of Table 1 was pressed for 60 minutes by a hot press to produce a plate having a thickness of 3 mm, and then hardness, 300% modulus, tensile strength, and elongation according to ASTM-related regulations. The thermal conductivity and fatigue test were measured before and after aging (100 ° C. × 24 hours), and the results are shown in Table 2 below.

division Comparative Example 1 Comparative Example 2 Example 1 Hardness (Shore A) 66 66 66 300% modulus 54 55 56 Tensile Strength (kg _f / cm ² ) 130 141 140 Elongation (%) 650 700 700 Thermal conductivity 0.360 ± 0.03 0.365 ± 0.03 0.365 ± 0.03 Fatigue test
(Demattia) Before aging 75,000 100,000 100,000 After aging
100 ℃ × 24 hours 25,000 80,000 100,000 Finished product evaluation phenomenon

Usage count Less than 200 Episode 215 320 times

* Hardness means higher hardness.

* Tensile properties (300% modulus, tensile strength, elongation) means that the higher the value, the better each characteristic.

* Fatigue test means that the higher the number of times, the higher the durability, for example, fatigue resistance.

* The higher the value, the better the heat transfer.

* Finished product evaluation shows the phenomenon (form change) that occurs internally after the actual vulcanization bladder is used. The number of times of use is the actual life, and the higher the value, the longer the life.

As shown in Table 2, the physical properties and fatigue properties were shown to be poor in the conventional manner, and in Comparative Example 2, the physical and fatigue properties were superior to those in the conventional manner. In Example 1, physical properties and thermal conductivity are shown to be on the same level as Comparative Example 2, and fatigue characteristics after aging have better results. In Comparative Examples 1 and 2, when the finished product is actually used due to the interference with the general filler due to the high crystalline micrographite, it causes defects such as bubbles, and the phenomenon is as shown in the above table. Has a lifespan of at least 100 times than in Comparative Examples 1 and 2.

Claims (6)

A first process in which a rubber polymer is used, a processing aid, a general filler and an oil are added in order, the undispersed filler is cleaned, and a thermally conductive additive is added therebetween;
A second process of mixing the first master batch 1/2, the neoprene and the first master batch 1/2 in order; And
And a third step of mixing the second master batch 1/2, the resin, ZnO and the second master batch 1/2 from the second process in order.
Process for producing a rubber composition using a three-batch mixing method. The method according to claim 1,
The Soviet Union time of the rubber polymer of the first step is 30 to 50 seconds, characterized in that the manufacturing method. The method according to claim 1,
The cleaning time of the said 1st process is a manufacturing method characterized by the above-mentioned. The method according to claim 1,
The thermally conductive additive of the first process is characterized in that the addition of 40 to 60rpm and 40 to 60 ℃ temperature control unit (TCU) temperature conditions. The method according to claim 1,
Mixing of the third process is carried out under the conditions of 40 to 60rpm and 40 to 60 ℃ TCU temperature. The method according to claim 1,
And further adding a thermally conductive additive between the first step and the second step.