JP3222054B2 - Rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a rubber composition, and more particularly, to a rubber composition having excellent kneading workability.
The present invention relates to a rubber composition having good mold release properties during molding and low surface tack of a molded article.

[0002]

2. Description of the Related Art It is common to incorporate several types of additives not directly involved in crosslinking into rubber compositions. This is a powder additive such as carbon black to adjust rubber properties such as hardness and strength, an additive to improve stability such as anti-aging, chemical resistance, ozone resistance, oxidation resistance, flexibility and hardness Plasticizers used for adjustment, further tackifiers, antiblocking agents, antistatic agents, mastication accelerators, coloring agents,
Generally, several types are selected from internal release agents and lubricants according to the purpose and added. Among these, a lubricant for improving the flowability at the time of kneading and molding and an internally added mold release agent for improving the mold release property at the time of molding are:
In recent years, it has attracted attention because of its great effect of improving work efficiency.

In particular, fluororubber, acrylic rubber, ethylene propylene rubber, etc., which have intense roll adhesion and are inferior in kneading workability, have a certain degree of compatibility with a rubber polymer to increase the fluidity and improve the kneading workability in order to improve the kneading workability. It is important to select a lubricant that reduces frictional resistance to the metal surface of the machine to prevent sticking and facilitate processing, and to study the amount of the lubricant. Generally, the chemical structure of a lubricant consists of a non-polar group and a small number of polar groups, but the polar group provides limited compatibility with the rubber polymer and it is believed that the non-polar group acts as a lubricant. Therefore, it is necessary to balance the contradictory properties of compatibility and lubricity. If the lubricity is too strong, the compatibility will be poor and bleed out to the surface, adversely affecting secondary processing such as adhesion and lamination of molded products. give. In addition, when performing mold molding, since there is no satisfactory internal release agent, in order to facilitate removal of a molded product, it is generally necessary to use a mold in advance rather than using the internal release agent. Application of a release agent (external release agent) has been performed.

Conventionally used lubricants include paraffin wax, liquid paraffin, paraffin and hydrocarbon resins such as polyethylene wax, fatty acids such as stearic acid, stearamide, oxystearamide, oleylamide and the like. Fatty acid esters such as fatty acid amides, butyl stearate, methylhydroxystearate, and ester-based waxes, fatty acid ketones such as ketone wax, higher alcohols, higher fatty alcohols such as higher alcohol esters, and esters represented by dimethylpolysiloxane A basic resin is exemplified. These are liquids or solids having a low melting point, and are usually added in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the rubber composition.

[0005] Although these lubricants improve kneading workability, they often cause inconvenience with regard to moldability. For example, the wettability to the metal is improved and the mold releasability is deteriorated, so that the product is stretched in order to forcibly remove it from the mold and deviates from the dimensional tolerance, and furthermore, the product is cut off. It may cause defective mold release. Furthermore, if the compatibility of the lubricant with the rubber polymer is small, the lubricant adheres to the mold during molding,
As the number of moldings increases, there is a disadvantage that the mold is contaminated and the surface condition of the product is deteriorated. In addition, since these lubricants have relatively poor heat resistance, they are used after molding to stabilize their physical properties, such as fluororubber and silicone rubber.
When post-curing must be performed at ~ 250 ° C, and the application of the molded product requires heat resistance, the thermally degraded lubricant reduces the physical properties or changes the surface state, and the coefficient of friction and adhesiveness There is a problem that it adversely affects the performance.

As the external release agent, organic surfactants, silicone-based polymers, fluorine-based polymers, and the like are generally used. However, it is difficult to apply these external release agents uniformly, and the dispersion by workers is difficult. There is a disadvantage that it is difficult to form a film having a stable thickness because of its large size. In addition, if the external release agent is used for a long period of time, the external release agent adheres to the mold and burns, which adversely affects the appearance and dimensional accuracy of the molded product. There is a problem.

[0007]

SUMMARY OF THE INVENTION Under the circumstances described above, the present invention solves the above-mentioned problems by using an improved lubricant and an internal release agent, particularly an additive having both performances. The present invention has been made to provide a rubber composition having improved processability, that is, excellent kneading workability and excellent mold releasability, as compared with the related art.

[0008]

[Means for Solving the Problems] 100 parts by weight of a fluororubber polymer, B. B. 0.01 to 10 parts by weight of a wax containing a fluorine-containing organic group and having a melting point of 30 to 200 ° C. Crosslinking agent selected from amines, polyols, and peroxides Amount sufficient to cure the component A.

Hereinafter, the present invention will be described in detail. In the present invention, the melting point of the component B containing a fluorine-containing organic group is 30.
Although the problem was successfully solved by using a wax at a temperature of up to 200 ° C., the component B was obtained by an esterification reaction of a higher alcohol and a carboxylic acid having a fluorine-containing organic group, and a higher fatty acid. Obtained by subjecting an alcohol having a fluorine-containing organic group to an esterification reaction, or obtained by subjecting an α-olefin to a hydrosilylation reaction with an organic silicon compound having a fluorine-containing organic group and a Si-H group. Any of them is suitable for the rubber composition of the present invention. Higher alcohols, higher fatty acids, and α-olefins, which are raw materials for the wax, have been conventionally used as lubricants to be added to rubber, but have been inferior in mold release properties and mold contamination. The reason is considered to be that polar molecules -OH, -COOH and double bonds are contained in the molecule.However, kneading workability and metallurgy can be achieved by using a compound in which a fluorine-containing organic group is bonded to the polar group. It has been clarified that the problem is solved, for example, the mold releasability is improved.

[0010] The fluorine content of the fluorine-containing organic group-containing wax used in the present invention is preferably 5 to 70% by weight. If the amount is less than 5% by weight, the molding workability may not be improved so much, and if it exceeds 70% by weight, the dispersibility in the rubber polymer and the kneading workability may decrease. Examples of the fluorine-containing organic group in the wax include the following. As a polyfluoroalkyl group, linear CF
_{3 (CF 2) 2 -,} CF 3 (CF 2) 3 -, CF 3 (CF 2) 5 -, CF 3 (CF 2) 7 -, CF
_{3 (CF 2) 9 -,} CF 3 (CF 2) 11 -, CF 3 (CF 2) 7 CH 2 CH 2 -, branched

Embedded image Divalent _{- (CF 2 CF 2) 2} -, - (CF 2 CF 2) 4 -, as polyfluoro ether group,

Embedded image As a polyfluoroalkenyl group,

Embedded image

The above-mentioned fluorine-containing organic group is added to a wax-like hydrocarbon compound by, for example, an ester bond, an ether bond,
The bond is formed via an amide bond, a siloxane bond, a silyl ester bond, or the like. Here, the wax-like hydrocarbon compound has a reactive group such as a hydroxyl group, a carboxyl group, an amino group, an unsaturated group, etc., and has a melting point of 30 to 200 ° C.
Is a hydrocarbon compound. The melting point of the resulting wax containing fluorine-containing organic groups is also important. If the melting point is lower than 30 ° C, the material is in a liquid state and slips during kneading work, which takes a long time to knead and significantly lowers work efficiency. Is the same as the effect of adding, and the releasing effect is reduced. Therefore, the melting point is 30 to 200 ° C, but preferably 50 to 180 ° C.

The amount of the wax containing a fluorine-containing organic group is 0.01 to 10 parts by weight based on 100 parts by weight of the fluororubber polymer. When the amount is less than 0.01 part by weight, kneading workability is not so improved, and when it is more than 10 parts by weight, rubber physical properties, particularly physical properties at the time of heating, are inferior. This is considered to be because the wax which has become liquid at the melting point or higher lowers the hardness and physical strength. In addition, since the wax containing a fluorine-containing organic group is relatively expensive, it is advantageous to add the necessary minimum amount in terms of cost, preferably 0.1 to 5 parts by weight.

The fluororubber polymer of the component A is a rubber having little effect with a conventional lubricant, having heat resistance, strong roll adhesiveness, and inferior mold release properties. It has been pointed out that fluororubber has been poor in roll kneading workability and mold forming workability, and no effective workability improvement means has been established at present. The present invention is most effective for this fluororubber.

The above fluororubber is a highly fluorinated elastic copolymer comprising vinylidene fluoride and hexafluoropropene, pentafluoropropene, trifluoroethylene, vinyl fluoride, perfluoro (methyl vinyl ether) , Perfluoro (propyl vinyl ether) and the like, and elastic copolymers with one or more kinds thereof. Among them, vinylidene fluoride-hexafluoropropene binary elastic copolymer, vinylidene fluoride- It is particularly effective for terpolymers of tetrafluoroethylene-hexafluoropropene. Further, two or more rubber polymers having different molecular weights or different molecular structures (copolymerization ratios) may be used in combination in order to lower the hardness of the fluororubber and to improve heat resistance and chemical resistance.

The crosslinking form of the fluororubber polymer is not particularly limited, and may be any of amine, polyol and peroxide crosslinking. Therefore, as the crosslinking agent for the component C, amine crosslinking agents such as hexamethylenediamine, polyol crosslinking agents such as bisphenol A and bisphenol AF, and peroxide crosslinking agents such as benzoyl peroxide and dimethyl ditertiary butyl peroxyhexane. Is exemplified. The rubber composition of the present invention may contain known triallyl isocyanurate, ammonium salts, phosphonium salts, magnesium oxide, calcium hydroxide, or other crosslinking aids, catalysts, acid acceptors, etc., in accordance with the crosslinking system. Is preferred.

It is optional to add a known filler or coloring agent in addition to the above-described components. Examples of the filler include carbon black, silica, alumina, red iron oxide,
Examples thereof include clay, calcium carbonate, titanium oxide, polytetrafluoroethylene powder, various conductive and heat-radiating fillers, and carbon black and silica are preferred from the viewpoint of reinforcement. These fillers may be treated with a silane-based or titanate-based surface treatment agent for the purpose of improving the dispersibility in the rubber polymer and the reinforcing property of the rubber polymer.

At the time of kneading the components, a rubber rubber 2 which has been conventionally used is used in order to completely disperse them.
The work corresponding to each composition may be performed by a roll, a kneader, a pressure kneader, a Banbury mixer, or the like. As a compounding order, if a wax containing a fluorine-containing organic group is added to the rubber polymer before adding other components, the compounding operation becomes easier, and the workability is improved as compared with the conventional one, so that a special device is not used. It is possible to knead easily.

As a molding apparatus for molding the rubber composition of the present invention, a conventionally used rubber processing machine can be used. For example, die molding by a rubber press machine, hot air vulcanization (HAV) by an extruder, etc. can be performed, and all have good workability as in kneading work, so any special equipment is used. It can be easily formed without any processing. Particularly with regard to mold molding, the releasability is good and the amount of the external release agent used is extremely small or no need to be used, so that the problem of mold contamination caused by the external release agent is reduced. The effect is extremely large.

The use of the rubber composition of the present invention facilitates handling of molded articles. In other words, rubber molded products are generally strong but have adhesiveness on the surface. Due to this adhesiveness, if the molded product is brought into contact for a long time in the presence of a certain amount of pressure or heat, the rubber will fuse together. Although the blocking phenomenon occurs, when the rubber composition of the present invention is used, the blocking phenomenon is suppressed, so that the handling of the molded article becomes easy.
Particularly, fluororubber needs to be subjected to high-temperature and long-time heat treatment in order to stabilize its physical properties. Therefore, the use of the rubber composition of the present invention makes it easier to handle molded articles.

[0020]

Next, embodiments of the present invention will be described with reference to examples. The components used in the following examples are as follows. A component: ・ Polyol cross-linked fluororubber (manufactured by Sumitomo 3M Limited,
・ FC3009 (trade name) ・ Peroxide crosslinked fluororubber (G8, manufactured by Daikin)
01) ・ Amine crosslinked fluororubber (B-50, manufactured by Showa Denko Dupont) ・ Polyol crosslinked fluorocarbon rubber (manufactured by Sumitomo 3M, FC2145) ・ Liquid fluororubber (manufactured by Daikin, product) Name G101)

Component C or related compounding agents: polyol-based crosslinking agent (bisphenol AF, Riedeld
ehaen) ・ Polyol crosslinking type low hardness compounding crosslinking agent (Shin-Etsu Chemical Co., Ltd., product name X-65-497) ・ Polyol crosslinking type low hardness compounding catalyst (Sumitomo 3M, product name FC2172) ・ Amine crosslinking agent (Manufactured by Daikin, trade name V-3)-Magnesium oxide (manufactured by Kyowa Chemical Co., Ltd., trade name Kyowa Mag # 30, # 150)-Calcium hydroxide (manufactured by Omi Chemical Industry Co., trade name: Caldic # 2000)-Peroxide Crosslinking agent (Shin-Etsu Chemical Co., Ltd., trade name C8-A) ・ Peroxide cross-linking aid (Nippon Kasei Co., Ltd., trade name, Tyck)

Wax not containing component B or fluorine: Wax 1 (trade name: X-70-108P, manufactured by Shin-Etsu Chemical Co., Ltd.)
... Esterification reaction product of higher alcohol and carboxylic acid having fluorine-containing organic group, melting point 91 ° C, fluorine content 26% by weight Wax 2 (Shin-Etsu Chemical Co., Ltd., trade name X-70-130W)
... Esterification reaction product of higher fatty acid and alcohol having fluorine-containing organic group, melting point 78 ° C, fluorine content 10
Weight% Wax 3 (Shin-Etsu Chemical Co., Ltd., trade name X-70-108D)
... hydrosilylation reaction product of an α-olefin and an organic silicon compound having a fluorine-containing organic group and a Si-H group,
Melting point 85 ° C, fluorine content 15% by weight ・ Polyethylene wax (manufactured by Allied Chemical Co., trade name: AC Polyethylene) Melting point 98 ° C ・ Paraffin wax (manufactured by Astor Petrochem, trade name)
Okerin333) Melting point 82 ° C Others: ・ MT carbon black (Harbour)

The evaluation of the rubber composition and its molded product was performed as follows. Kneading property: The kneading operation was performed on a rubber polymer 2 kg scale using two 8-inch rubber rolls, and the time (minutes) required for the kneading operation was shown. -Releasability: Use a chrome-plated mold for JIS P0024 size 6-piece O-rings, and first add 10% by weight to this mold.
Release agent diluted in water (Sumitomo 3M, trade name F
C5158) was applied, and thereafter, molding was repeated without application. -Physical properties of molded article: Measured according to JIS K6301.

[0024]

【Example】

Examples 1 to 3 and Comparative Examples 1 to 3 Using the components described above, rubber compositions were prepared according to the following formulation. In addition, the case where the wax 1 corresponding to each of Examples 1-3 was not mix | blended was set as Comparative Examples 1-3. Table 1 shows the evaluation results.
Shown in With the addition of wax, the kneading workability and mold release properties are extremely good, and the physical properties of the molded product are hardly changed (that is, the addition of wax has no adverse effect) and the surface tackiness is lower than when no wax is added. Less.

Example 1 Polyol crosslinked fluororubber 100 parts by weight MT carbon black 3 parts by weight Calcium hydroxide 3 parts by weight Magnesium oxide # 150 3 parts by weight Polyol crosslinker 4 parts by weight Wax 11 parts by weight Example 2 Amine crosslinking 100 parts by weight of fluorinated rubber MT carbon black 10 parts by weight Magnesium oxide # 30 15 parts by weight Amine crosslinking agent 3 parts by weight Wax 1 1 part by weight Example 3 100 parts by weight of peroxide crosslinked fluorinated rubber 10 parts by weight MT carbon black Water Calcium oxide 3 parts by weight Peroxide crosslinker 3 parts by weight Peroxide crosslinker 3 parts by weight Wax 1 1 part by weight

[0026]

[Table 1]

Example 4 and Comparative Example 4 Using the above components, a rubber composition was prepared according to the following formulation. In addition, the case where the wax 2 was not blended was set as Comparative Example 4. Table 2 shows the evaluation results. This compound is a large amount of liquid fluoro rubber added to reduce the hardness of the fluoro rubber, but by adding wax, kneading workability,
The mold releasability was improved, and the physical properties of the molded product were hardly changed. Example 4 Polyol-crosslinked low-hardness compounding fluororubber 100 parts by weight Liquid fluororubber 40 parts by weight MT carbon black 1 part by weight Calcium hydroxide 3 parts by weight Magnesium oxide # 150 3 parts by weight Polyol-crosslinking low-hardness compounding crosslinker 10 parts by weight Polyol cross-linking low hardness blending catalyst 6 parts by weight Wax 2 1 part by weight

Example 5 With the same composition as in Example 4, the amount of wax 2 added was increased from 1 part by weight to 3 parts by weight. Table 2 shows the evaluation results. By increasing the amount of wax, mold releasability is further improved,
The molded product was easily taken out of the mold not only when an external release agent was used but also when it was not used, and the molding workability was extremely excellent. Moreover, there was almost no change in the physical properties of the molded product due to the increase in the amount of wax.

Example 6 A rubber composition was prepared in the same manner as in Example 4 except that wax 3 was used instead of wax 2. Table 2 shows the evaluation results. Also in this example, the kneading workability and the mold release property were improved by adding the wax, and the physical properties of the molded product were hardly changed.

Comparative Example 5 In the formulation of Example 4, instead of the wax 2, polyethylene wax, which is a lubricant often used in molding of a fluororubber, was blended. Table 2 shows the evaluation results. Although the change in physical properties of the molded product due to the blending of polyethylene wax is small, the workability of kneading is inferior. In addition, it is impossible to take out from the mold immediately with repeated molding of the O-ring to evaluate the releasability. Therefore, the rubber composition was clearly inferior in workability as compared with Example 4.

Comparative Example 6 In the composition of Example 4, instead of the wax 2, a paraffin wax, which is a lubricant often used in molding a fluororubber, was blended. Table 2 shows the evaluation results. Although there was little change in the physical properties of the molded product due to the incorporation of paraffin wax, the processability was exactly the same as that of Comparative Example 5, and the rubber composition was clearly inferior in processability to Example 4.

[0032]

[Table 2]

[0033]

According to the present invention, a rubber composition having excellent processability is provided. The rubber composition of the present invention has better kneading workability and better mold release properties than conventional rubber compositions, and the physical properties of a molded product obtained from this rubber composition are not different from those of the conventional rubber composition.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI C08L 91:00) C08L 91:00) (58) Investigated field (Int.Cl. ⁷ , DB name) C08L 27/12 C08K 5 / 05 C08K 5/14 C08K 5/17 C08L 91/00

Claims (5)

(57) [Claims] 1. A. First Embodiment 100 parts by weight of a fluororubber polymer, B. B. 0.01 to 10 parts by weight of a wax containing a fluorine-containing organic group and having a melting point of 30 to 200 ° C. A rubber composition comprising a crosslinking agent selected from an amine, a polyol, and a peroxide in an amount sufficient to cure the component A. 2. The fluorine content of the wax of component B is 5 to 70.
The rubber composition according to claim 1, which is in terms of% by weight. 3. The rubber composition according to claim 1, wherein the wax as the component B is obtained by subjecting a higher alcohol and a carboxylic acid having a fluorine-containing organic group to an esterification reaction. 4. The rubber composition according to claim 1, wherein the wax as the component B is obtained by subjecting a higher fatty acid and an alcohol having a fluorine-containing organic group to an esterification reaction. 5. The component B wax obtained by subjecting an α-olefin and an organosilicon compound having a fluorine-containing organic group and an Si—H group to a hydrosilylation reaction.
Or the rubber composition according to 2.