JPH02158639A - Cold-resistant plasticized rubber composition - Google Patents

Abstract

PURPOSE:To obtain a cold-resistant plasticized rubber composition improved in cold, extraction, heat resistance, etc., by blending rubber with a specific ester compound. CONSTITUTION:A composition obtained by blending 100 pts.wt. rubber with 2-50 pts.wt., preferably 5-30 pts.wt. ester compound expressed by the formula (A is 2-4C alkylene; l and m are >=1; R is 1-12C alkylene).

Description

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

[Problems to be solved by the prior art and the invention] -i. Softeners or plasticizers are used to reduce the hardness of various rubbers and synthetic resins, give them flexibility, increase their elasticity, and improve processability. is used.

For these purposes, various oils and fats, paraffins, aromatic oils, phthalates, dibasic fatty acid esters, phosphoric esters, epoxy compounds, and chlorine plasticizers have been used. . Originally, plasticizers 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, and transparency. Although plasticizers are required to have excellent properties, the use of plasticizers has so far been carried out by appropriately combining the above-mentioned plasticizers according to each application.

However, as the use of rubber and synthetic resins containing these plasticizers expands, such as outdoor use in cold regions, conventional combinations of plasticizers alone cannot sufficiently satisfy all required properties ( It has become.

For example, nitrile rubber has extremely strong stickiness among synthetic rubbers, so it has excellent oil resistance and adhesive properties, and also has a good balance of physical properties and processability, so it is used in industrial applications such as sealing materials, backing materials, and hoses. Widely used in the fields of supplies, rolls, footwear, adhesives, etc. The purpose and mechanism of action of the plasticizer for nitrile rubber are similar to the purpose and mechanism of action of the plasticizer for polyvinyl chloride resin, so many plasticizers for polyvinyl chloride resin are used as they are for nitrile rubber.

However, depending on its use, nitrile rubber is often used in contact with oil or solvent, and is often used at high temperatures. Cold resistance is also required for oil-resistant parts for aviation and other fields. Therefore, it has been desired that a plasticizer for nitrile rubber has not only a plasticizing effect but also properties such as oil resistance, cold resistance, and heat aging resistance. However, in general, plasticizers with excellent cold resistance tend to bleed, are easily extracted by petroleum oils, and have a large volatilization loss when heated, so it has been difficult to achieve both of these properties.

That is, conventionally, dibutyl phthalate, dioctyl phthalate, tricresyl phosphate, etc., which have relatively well-balanced properties, have been used as plasticizers for nitrile rubber. However, these plasticizers have poor cold resistance and do not have sufficient performance in fields where cold resistance is required.

On the other hand, cold-resistant plasticizers include aliphatic diesters such as dioctyl adipate, dibutyl sebacate, dioctyl sebacate, dioctyl azelade, and methyl acetyl lysyllate, dibutoxyethyl sebacate, di(butoxyethoxyethyl) adipate, and triethylene glycol. Ether alcohol derivatives such as diethylhexylate, tributoxyethyl phosphate, butylcarpitol formal, and high molecular weight aliphatic polyethers have been used, but these plasticizers are not sufficiently compatible with nitrile rubber, and the amount added is limited. There was a drawback that if the amount exceeded 30 copies, bleeding would occur.

Moreover, since these cold-resistant plasticizers are commonly easily extracted by oily substances, they have the serious drawback of significantly impairing their cold resistance 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 out, it loses its initial cold resistance, causing the hose to crack at low temperatures. This was a big problem as there were cases where it could break or even break.

In addition, in sealing parts such as gaskets, O-rings, and various backing materials, plasticizers are extracted from the oil that comes in contact with them, causing thinning of the flesh and oil leakage, as well as loss of flexibility at low temperatures. Normal operation may become impossible.

Therefore, for example, fatty acid diesters of alkylene glycol or polyoxyalkylene glycol (JP-A No. 62-25643), dibasic acid esters of alkoxypolyglycol (JP-B No. 54-44695), butoxytriglycol and thioglycol derived from Polyether plasticizers (U.S. Pat. No. 3,163,620) have been proposed, and cold resistance and extraction resistance have been improved to some extent, but they are still insufficient. There has been a desire for a cold-resistant plasticizer that has excellent compatibility with rubber and also has excellent properties inherent in rubber, as well as physical and chemical properties.

[Means for Solving the Problems] In view of the above-mentioned current 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. As a result, by adding to the rubber a specific ester compound that is structurally very similar to known additives, superior performance that could not be obtained with known plasticizers - cold resistance, extraction resistance, and other physical properties. It has been found that a rubber can be obtained which has satisfactory performance in all of the chemical properties, and is economically inexpensive.

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

(In the formula, A represents an alkylene group having 2 to 4 carbon atoms and 1
．． (and `` and `` each independently represent a number of 1 or more, and `` `` represents an alkylene group having 1 to 12 carbon atoms.)

In the above-mentioned maximum, the alkylene group having 2 to 4 carbon atoms represented by A is, for example, ethylene, 1,2-propylene, 1,3-propylene, 1,2-butylene, 1
．． Examples include groups such as 3-butylene, 2,3-butylene, and 1,4-butylene, with ethylene and 1,4-butylene groups being particularly preferred in terms of cold resistance.

1 and m are not particularly limited as long as they are 1 or more, but if they are too large, cold resistance tends to decrease, so it is generally preferable that they are 1O or less.

Examples of the residue include malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, superric acid, decanedicarboxylic acid, dodecanedicarboxylic acid, methylsuccinic acid, α
-Carboxylic acid residues such as methyladipic acid.

The ester compound represented by maximum (1) above is synthesized by a commonly known esterification reaction.

For example, an aliphatic dibasic acid and methylpolyglycol can be synthesized by a heated dehydration reaction in the presence of a conventional esterification catalyst.

The general formula (
The amount of the ester compound represented by 1) varies depending on the type of rubber used and its purpose, but is usually 2 to 50 parts by weight, preferably 5 to 30 parts by weight, and less than 100 parts by weight of rubber. However, the effect on cold resistance is insufficient,
In addition, if you use more than this, not only will the extraction resistance be inferior,
The rubber becomes too soft, which is unfavorable in terms of the physical properties of the rubber.

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

In order to obtain the rubber composition of the present invention by blending the cold-resistant plasticizer represented by maximum (1) above, ordinary rubber kneading methods can be applied, such as open roll, Banbury mixer, Niderprender etc. are used depending on the purpose.

Regarding other compounding agents added when manufacturing the rubber composition of the present invention, those usually added to rubber, such as vulcanizing agents, vulcanization accelerators, anti-aging agents, fillers, softeners, Processing aids and the like can be added as necessary.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to synthesis examples of cold-resistant plasticizers according to the present invention and examples of the present invention, but the present invention is not limited in any way by the following examples.

Synthesis example dimethycitrig 1col adipate 262.8g (1°8 mol) of adipic acid, 7 methyltriglycol
08.5 g (4.32 g mol), 4.9 g of activated carbon, and 0.19 g of dibutyltin oxide were taken, and 2
The mixture was stirred at 20° C. for 8 hours while removing produced water. After that, reduce the pressure of the reaction system and add 2 more times until the acid value becomes 1 or less.
Stirring was continued for an hour. 15++ml of excess alcohol
It took 1.5 hours to remove under a vacuum of 1.5 g. The product was filtered through Celite to obtain 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 511; TO
(AP)IA), Example 1 In order to examine the excellent properties of the cold-resistant plasticized rubber composition of the present invention, based on the following formulation using nitrile rubber,
After open roll kneading and compounding, vulcanization was performed at 150°C for 20 minutes, and tests were conducted for compatibility, tensile strength, elongation, cold resistance, and heat resistance. Further, an immersion test (oil resistance test) using JIS-1 oil was conducted.

Display those results. combination N1pol 1041” zinc oxide sulfur yellow stearic acid Carbon black 100 parts by weight 0.3 Shown in 1.

Plasticizer (Table-1) 20 Note) *l: Low-temperature polymerization high nitrile NBI made by Nippon Zeon? Example 2 Using a vulcanized sheet obtained with the same formulation as Example 1, JI
The cold resistance was measured after being immersed in No. S-1 oil at 100°C for 70 hours. In addition, cold resistance was measured after immersing in fuel oil (Fuel C: isooctane/toluene-50150 volume ratio) at 40'C for 70 hours and drying at 100°C for 2 hours.

The results are shown in Table 2 below.

Example 3 Produced L/L with the following formulation using epichlorohydrin rubber.
The physical properties and oil resistance of the sheet after vulcanization were measured at 170°C for 15 minutes and at 150°C for 4 hours, and the results are shown in Table 3 below.

Blended Zeclon 3102" 100 parts by weight Sorbitan monostearate 3 Magnesium oxide 3 Calcium carbonate 5 Carbon black 60 Santoguard PVI m"1. O Ni dibutyl dithiocarbamate 1.5 Plasticizer (Table 3) 20 Note) *2: Epichlorohydrin rubber manufactured by Nippon Zeon Book 3: Vulcanization retarder manufactured by Mitsubishi Monsanto Chemical [Effects of the invention] The plasticizer according to the present invention is Not only does it significantly improve the cold resistance of rubber, but it also has excellent extraction resistance, so even when used in environments where it comes into contact with oil or fuel oil, it retains its initial excellent cold resistance, while also maintaining its heat resistance. N
In addition to BR or hydrin rubber, it can also be applied to rubbers that require a high degree of heat resistance, such as acrylic rubber or hydrogenated NBR.

Applicant's agent Kaoru Furutani

Claims (1)

[Scope of Claims] A cold-resistant plasticized rubber composition characterized by containing an ester compound represented by the following general formula (1). ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, A represents an alkylene group having 2 to 4 carbon atoms,
and m each independently represent a number of 1 or more, and R represents an alkylene group having 1 to 12 carbon atoms).