JP2602541B2 - Cold-resistant plasticized rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a cold-resistant plasticized rubber composition,
The present invention relates to a plasticized rubber composition that not only improves non-extractability and cold resistance to oily substances, but also improves heat resistance, physical and chemical properties.

[Problems to be solved by conventional technology and invention]

In general, a softener or a plasticizer is used to lower the hardness of various rubbers and synthetic resins to impart flexibility, increase elasticity, and improve workability.

For these purposes, various fats and oils, paraffins, aromatic oils, phthalates, dibasic fatty acid esters, phosphates, epoxy compounds, chlorine plasticizers and the like have been used. . Originally, the plasticizer should have many properties such as compatibility with rubber and resin, plasticization efficiency, cold resistance, migration resistance, extraction resistance, volatility resistance, weather resistance, heat aging resistance, transparency, etc. Although it is required to have excellent properties, the use of plasticizers has hitherto been practiced by appropriately combining the above-mentioned plasticizers according to each application. However, as the use of rubbers and synthetic resins containing these plasticizers for outdoor use in cold regions is expanding, it is no longer possible to sufficiently satisfy all the required properties only with the combination of conventional plasticizers. Was.

For example, nitrile rubber has excellent oil resistance and adhesiveness because it is extremely polar among synthetic rubbers, and also has a good balance of physical properties and workability, so it can be used for sealing materials, packing materials, hoses, boots, etc. Widely used in the fields of industrial supplies, rolls, footwear, adhesives and the like. Since the purpose and mechanism of action of the plasticizer for the nitrile rubber are similar to those of the plasticizer for the polyvinyl chloride resin, most of the plasticizers for the polyvinyl chloride resin are used as they are for the nitrile rubber.

However, nitrile rubber is used for oil,
It is often used in contact with a solvent, and is often used at a high temperature. Oil resistance parts for aviation and other fields also require cold resistance. Therefore, a plasticizer for nitrile rubber that has not only a plasticizing effect but also properties such as oil resistance, cold resistance and heat aging resistance has been desired. However, plasticizers having excellent cold resistance generally tend to cause bleeding, are easily extracted into petroleum-based oils, and have a large amount of volatilization loss upon heating.

That is, conventionally, as a plasticizer for nitrile rubber, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, and the like, which have relatively balanced properties, have been used. However, these plasticizers are inferior in cold resistance, and thus do not have sufficient performance in fields requiring cold resistance.

On the other hand, as a cold-resistant plasticizer, dioctyl adipate,
Aliphatic diesters such as dibutyl sebacate, dioctyl sebacate, dioctyl azelate, methyl acetyl silinolate, dibutoxyethyl sebacate, di (butoxyethoxyethyl) adipate, triethylene glycol diethylhexylate, tributoxyethyl phosphate, butyl Carbitol formal, ether alcohol derivatives such as high molecular weight aliphatic polyethers have been used, but these plasticizers are not sufficiently compatible with nitrile rubber and cause bleeding when the added amount exceeds 30 parts. There were drawbacks.

In addition, since these cold-resistant plasticizers are commonly easily extracted into an oily substance, they have a serious disadvantage that the cold resistance is greatly impaired after the immersion test. For example, when used in applications such as fuel hoses, the plasticizer in the hose is easily extracted into the fuel oil, and when the hose dries, the initial cold resistance is lost, so the hose cracks at low temperatures In some cases, it was broken, which was a major problem.

In addition, in a sealing member such as a gasket, a 0-ring, various packing materials, a plasticizer is extracted into a contacting oil,
Not only causes meat thinning, causing oil leakage,
In some cases, flexibility at low temperatures is lost and the original operation becomes impossible.

Therefore, for example, fatty acid diesters of alkylene glycol or polyoxyalkylene glycol (JP-A-62-253643), dibasic acid esters of alkoxypolyglycol (JP-B-54-44695), and derivatives derived from butoxytriglycol and thioglycol. Polyether plasticizers (US Pat. No. 3,163,620) have been proposed, and the cold resistance and extraction resistance have been improved to some extent. There has been a demand for a cold-resistant plasticizer that has excellent compatibility with rubber and also has excellent properties inherent in rubber, physical and chemical properties.

[Means for solving the problem]

In view of the above situation, the present inventors have conducted intensive studies to develop a cold-resistant plasticizer that improves not only the cold resistance of rubber but also the extraction resistance and other properties, and as a result, known additives and By adding a specific ester compound that is structurally very close to the rubber, excellent performance-cold resistance, extraction resistance, other physical and chemical properties-that could not be obtained with known plasticizers- It has been found that a rubber having satisfactory performance and economical inexpensiveness can be obtained.

The present invention has been made based on the above findings, and provides a cold-resistant plasticized rubber composition containing an ester compound represented by the following general formula (I).

(Wherein, A represents an alkylene group having 2 to 4 carbon atoms,
_L and m each independently represent a number of 1 to 10, and R represents an alkylene group having 1 to 12 carbon atoms).

In the above general formula, examples of the alkylene group having 2 to 4 carbon atoms represented by A include ethylene, 1,2-propylene, 1,3-propylene, 1,2-butylene, 1,3-butylene, Examples thereof include groups such as 3-butylene and 1,4-butylene, and ethylene and 1,4-butylene groups are particularly preferable in terms of cold resistance.

_L and m are not particularly limited as long as they are 1 or more. However, if _L and m are too large, the cold resistance tends to decrease.

Also, Examples of the dicarboxylic acid residue represented by, for example, malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid,
Carboxylic acid residues such as suberic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, methylsuccinic acid and α-methyladipic acid are exemplified.

The ester compound represented by the general formula (I) is synthesized by a commonly known esterification reaction. For example, an aliphatic dibasic acid and methyl polyglycol can be synthesized by a heat dehydration reaction in the presence of a usual esterification catalyst.

The amount of the ester compound represented by the general formula (I) used as the cold-resistant plasticizer for rubber in the present invention varies depending on the type and use of the rubber used, but usually ranges from 2 to 50 parts per 100 parts by weight of rubber. Parts by weight, preferably 5 to 30 parts by weight, below which the effect on cold resistance is insufficient, and when used more than this, not only is the extraction resistance inferior, but also the rubber becomes too soft and the physical properties of the rubber Not preferred in terms of surface.

Rubbers using the cold-resistant plasticizer of the present invention include natural rubber (NR), polybutadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), and polyisoprene. It can be applied to all rubbers such as rubber and synthetic rubber such as ethylene-propylene rubber, and can be applied to both sulfur vulcanization and peroxide crosslinking, and can be used in combination with these rubbers and ordinary synthetic resins. It can also be applied to polymers or blends.

In order to obtain the rubber composition of the present invention by blending the cold-resistant plasticizer represented by the above general formula (I), a usual rubber kneading method can be applied. For example, an open roll, a Banbury mixer, a kneader A blender or the like is used depending on the purpose.

With respect to other compounds added when producing the rubber composition of the present invention, those usually added to rubber, for example,
Vulcanizing agents, vulcanization accelerators, antioxidants, fillers, softeners, processing aids, etc. can be added as required.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Synthesis Examples of the cold-resistant plasticizer according to the present invention and Examples of the present invention. However, the present invention is not limited by the following Examples.

Synthesis Example Synthesis of di (methyltriglycol) adipate Take 262.8 g (1.8 mol) of adipic acid, 708.5 g (4.32 gmol) of methyltriglycol, 4.9 g of activated carbon and 0.19 g of dibutyltin oxide, and place them at 220 ° C. under a nitrogen stream. The mixture was stirred for 8 hours while removing generated water. Thereafter, the pressure of the reaction system was reduced, and stirring was continued for another 2 hours until the acid value became 1 or less.
Excess alcohol was removed under reduced pressure of 15 mmHg in 1.5 hours. The product was filtered through celite to give 772 g of the desired plasticizer as a pale yellow liquid.

Acid value: 0.09, hydroxyl value: 1.5 Viscosity: 30 cp (25 ° C.), color tone: 70 (APHA), Example 1 In order to see the excellent properties of the cold-resistant plasticized rubber composition according to the present invention, nitrile rubber was used. Based on the following formulas used, open roll kneading and blending were performed, and then vulcanization at 150 ° C. for 20 minutes was performed to test compatibility, tensile strength, elongation, cold resistance and heat resistance. An immersion test (oil resistance test) using JIS No. 1 oil was also performed.

 The results are shown in Table 1.

Combination Nipol 1041 ^{* 1} 100 parts by weight Zinc oxide 5 Sulfur Yellow 0.3 Stearic acid 1 Carbon black 50 Tetramethylthiuram disulfide 2.0 N-Cyclohexyl-2-benzothiazylsulfolamide 1.5 Plasticizer (Table-1) 20 Note) * 1: Low temperature polymerization high nitrile NBR manufactured by Zeon Corporation Example 2 Using the vulcanized sheet obtained with the same composition as in Example 1,
Cold resistance after immersion in S-1 oil at 100 ° C. for 70 hours was measured. Fuel oil (Fuel C: isooctane / toluene = 50 /
(50 volume ratio) at 40 ° C. for 70 hours, and subjected to a drying treatment at 100 ° C. for 2 hours to measure cold resistance.

 The results are shown in Table 2 below.

Example 3 Pressing with the following composition using epichlorohydrin rubber
The physical properties and oil resistance of the sulfuric acid sheet were measured at 170 ° C. for 15 minutes and post-cure at 150 ° C. for 4 hours.
3 is shown.

Combination Zeklon 3102 ^{* 2} 100 parts by weight Sorbitan monostearate 3 Magnesium oxide 3 Calcium carbonate 5 Carbon black 60 2,4,6-trimercapto-s-triazine 0.9 Santogard PVI ^{* 3} 1.0 Ni dibutyl dithiocarbamate 1.5 Plasticizer (Table-3) 20 Note) * 2: Epichlorohydrin rubber manufactured by Zeon Corporation * 3: Vulcanization retarder manufactured by Mitsubishi Monsanto Kasei [Effect of the Invention] The plasticizer according to the present invention not only significantly improves the cold resistance of rubber, but also has excellent extraction resistance, so that it can be used even in an environment where it comes into contact with oil or fuel oil. , Because it retains excellent initial cold resistance and also has excellent heat resistance,
In addition to NBR or hydrin rubber, it can be applied to rubber requiring high heat resistance such as acrylic rubber or hydrogenated NBR.

Claims (1)

(57) [Claims] 1. A cold-resistant plasticized rubber composition comprising an ester compound represented by the following general formula (I). (Wherein, A represents an alkylene group having 2 to 4 carbon atoms,
_L and m each independently represent a number of 1 to 10, and R represents an alkylene group having 1 to 12 carbon atoms).