JPS58113235A - Anti-blooming agent and rubber composition - Google Patents

Abstract

PURPOSE:To obtain a rubber composition with sulfur blooming being effectively suppressed without impairing the properties of cured products and curing reaction, by using an alkylolamide as an antiblooming agent. CONSTITUTION:The objective composition can be obtained by incorporating (A) a composition comprising (i) 100pts.wt. of a rubber selected from natural rubber, synthetic rubbers or blends derived from those and (ii) 2-10pts.wt. of sulfur as a curing agent with (B) 0.05-3(pref. 0.2-1)pts.wt. of an alkylolamide of formula[R is 5-24C acyl; A is 2-4C alkylene; R' is (AO)nH (n is 0 or an integer >=1) or 1-24C-hydrocarbon group; m is an integer >=1; m+n : 1-40]with a weight ratio (ii)/(B) being pref. 100/2-100/5. In preparing said alkylolamide, a molar ratio of fatty acid to alkanolamine would preferably be 1/0.7-2.5, especially 1/1-2.

Description

[Detailed Description of the Invention] Related. For more details, see Vulcanized Oj with improved sulfur bloom.
The present invention relates to a rubber composition capable of

In the coloring process of rubber products such as tires and conveyor belts, dissimilar materials such as rubber and rubber or rubber and gold paste or synthetic fibers often have to be bonded together, and the adhesiveness of unvulcanized rubber, so-called tackiness, is often required. It is well known that ensuring the same has a big impact on work efficiency and productivity.

Normally, non-III bonded with such similar or dissimilar materials
In IJ sulfur rubber members, there is a phenomenon in which the adhesive strength changes over time and decreases, especially in the bonded parts.

One of the causes of L is that when left unvulcanized for a long time, a part or all of the bonded area of unvulcanized rubber parts develops a foreign part that is extremely inferior to the original adhesive strength of unvulcanized rubber. There is a so-called bloom phenomenon that reduces wet interviews.
In particular, the phenomenon of plume plume on the vulcanized side strongly requires improvement of sulfur bloom as an indispensable condition for rubber compositions in order to significantly reduce the adhesion and adhesive strength of unvulcanized rubber. has been done.

Particularly in recent years, steel radial front tires have become popular due to their excellent fuel efficiency and maneuverability, but the steel cord electrified rubber of such tires gains adhesive strength by increasing the adhesive reaction between the steel cord and the rubber. Therefore, there is a tendency to use compounds for polysulfur equipment, and it is increasingly desired to suppress sulfur bloom in order to ensure workability and productivity.

Conventional technology for suppressing sulfur bloom involves heating the rubber compound in a roll, calendering process in a mixer, etc., and melting ordinary sulfur containing 114 cyclic teeth.
Focusing on the fact that s8) precipitates as self-saturated sulfur and crystallizes when cooled, it is common to use sulfur in the form of sulfur that cannot be dissolved in rubber, or sulfur with tIA that can be dissolved in rubber. It was a target. An example of the former is the use of insoluble sulfur (molecular sulfur) as described in Japanese Patent Publication No. 3, 4-13075. However, insoluble sulfur has a transition temperature to S8 of about tOS
~/10°C, so it is necessary to control the calender speed and extrusion speed in the calendering and extrusion processes so that the processing temperature does not exceed the transition temperature, especially for high elastic modulus rubbers and high heat generation rubbers. As a result, not only does this result in a decrease in productivity, but also the fractional nature of insoluble sulfur itself is steep, and there is a problem in that it is difficult to produce products with uniform physical properties due to the physical properties of the sulfur.

In addition, in order to suppress the temperature rise in the processing process, an attempt was made to improve the sulfur plume by using polyisoprene rubber with good fluidity and suppressing the transition of insoluble sulfur to 88. Although this method is described in Sho Sr-/J7,2Q, it is not always a satisfactory method because it requires impregnated rubber and is subject to various formulation restrictions.

For example, green modulus and green fineness decrease due to converting natural rubber into polyisobrene rubber;
There are also disadvantages in that the vulcanization does not give the same physical properties as natural rubber, and the method cannot be applied to compositions that do not contain polyisoprene or natural rubber.

An example of the latter is the use of a sulfur donor described in Japanese Patent Publication No. 7-6μ9l. However, since the molecule of a sulfur donor is not composed only of sulfur, not only is the efficiency of sulfur donation lower and the cost is too long, but usually only a monosulfide bond is provided as the bond at the crosslinking point. This method has the following drawbacks, and has not been applied to fields where economic efficiency is important.

Therefore, it has been desired to develop a method that can be applied to conventional ordinary sulfur (S8) and has the effect of suppressing optical sulfur bloom.

From this point of view, the present applicant has published Japanese Patent Application Laid-Open No. 102119-102119.
No. and Tokukaisho! No. 41-/10210 proposed a rubber composition using 11 flJ, an effective sulfur bloom suppressing additive when used in combination with ordinary 88 or insoluble sulfur. Although these supplements 11 [1 cut] are superior to the conventional method in terms of the fact that there are enough young fruits for S8 produced by the transfer of insoluble sulfur and the economical quotient, there are still some drawbacks. Was. That is, sorbitan esters, diethylene glycol esters, polyoxyethylene nonylphenol, etc. used as sulfur plume suppressing agents still have insufficient plume suppressing effects, and alkyl xanthate gold maple salts such as potassium ethyl xanthate are DOk. Since fl acts as a super vulcanization accelerator in
The t+wax reaction is severely accelerated (burning of the rubber occurs during the extrusion process and rolling process, resulting in a severe deterioration of the workability), and has a large impact on the addition and physical properties (the modulus of the rubber increases, elongation at break increases). As a result, only slight wrinkles could be added, and since the odor was strong, it was a problem in terms of factory hygiene.

Therefore, it has been desired to develop an additive for suppressing sulfur plumes that has a sufficient ability to suppress sulfur plumes with noit that does not significantly affect the vulcanization properties or the 1110 sulfur reaction.

In view of this current situation, the present inventors fraudulently studied the mechanism of the generation of sulfur plume, and by treating sulfur in rubber with an amide compound having a specific chemical substance different from that of the additive, DO sulfur reaction! without significantly affecting the physical properties of lO sulfur or its contact with steel cord.
Furthermore, it was confirmed that sulfur plumes could be suppressed extremely effectively without confining the work environment, and the present invention was achieved.

(In the formula, R is the number of carbon atoms!-JII acyl 4i residue M, A is an alkylene group having 2 to μ carbon atoms, R1 is 100 μm) nH& or a hydrocarbon group having carbon number/−2 h, m is an integer greater than or equal to 1, n is O or an integer greater than or equal to 1, m+n=/-IO
Sulfur plume prevention cutting of rubber consisting of an alkylolamide compound shown in As kt&
A rubber composition containing 2 to 10 @ lid part is mixed with the following general formula (R is an acyl group having a carbon number of s to 2μ, M is an alkylene group having a carbon number of λ to tei, R/ represents a hydrocarbon group of nH & or return lk/~koda, m is Minetoshi of 1 or more, n is O or an integer of 1 or more, m0n=/-40
This is a III sulfurable rubber composition (IJ invention) which has improved sulfur plume and is characterized by containing an alkylolamide compound.

In the general formula (I), R is an acyl group having a carbon number of r-J&, preferably 9%-20 (from an acyl group to -CO-
) and includes aliphatic, alicyclic and aromatic hydrocarbon groups. Alicyclic hydrocarbon groups include saturated or unsaturated hydrocarbon groups, such as alkyl groups having a carbon number of j to 2μ (pentyl group, 2-ethylhexyl group, octyl group, nonyl group, undecyl group, tridecyl group, pentadecyl group, hexadecyl group). , heptadecyl group, eicosyl group, etc.), alkenyl groups (oleyl group, etc.), lylyl group, and lylyl group. The alicyclic hydrocarbon group is cyclohexyl, and the aromatic hydrocarbon group is aryl (phenyl, naphthyl, etc.), aryl substituent [arylalkyl group (Hensyl group, 7-enethyl group, etc.)], and arylalkenyl group. (cinnamyl group, etc.)), fit-converted aryl paper [alkylaryl &
(Aryl substituted with an alkyl group having 1 to 11 carbon atoms (gotryl and nonylphenyl &)] is opened.

The acyl group residue may have a substitution (such as at OH1), such as OHJili [substituted aliphatic hydrocarbon group (OH1 substituted alkenyl group, e.g. lysyllenyl group) and aromatic hydrocarbon group substituted at OH1 (OH1 substituted aryl group). The basic analogy is Saliciro Iru Sakazan I!i).

Among R, the preferred ones are alkyl groups of carbon numbers 9 to 20, alkenyl groups, and 0H1l! , [substituted alkenyl groups, particularly preferred groups are pentadecyl group, heptadecyl group and oleyl group.

is an alkylene group with 11 carbon atoms, ethylene pig,
Examples include propylene and butylene groups. Preferred among these groups are ethylene groups and propylene groups.

R' is +AO)nH or carbon number/-2μ hydrocarbon 3I
This hydrocarbon group includes a lower alkyl group and R
Of the OF2 which can be used as a hydrocarbon group such as methyl, ethyl, cyclohexyl, etc., the preferred one is 0)nH.

man is /-4t01 preferably /-20, particularly preferably 1 to J.

Regarding m and n, since the improvement effect on sulfur bloom is excellent when m+H is in the range of / -440 (F), it is necessary that man be in the above range.

Specific examples of the alkylolamide compound represented by the general formula (I) include reaction products of fatty acids having usually t to 2s carbon atoms and alkanols, and alkylene oxide C02-04) adducts thereof. There is. The fatty acids used include saturated fatty acids (lauric acid, valmitic acid, stearic acid, etc.), unsaturated fatty acids (oleic acid, linoleic acid, linuric acid, etc.), mixed fatty acids (coconut oil fatty acids, etc.), and hydroxyl fats1! ! ! (ricinol N), their methyl esters and glycerin esters (oils and fats), among which palmitic acid, stearic acid and oleic acid are preferred. When oils and fats are used, glycerin produced by the amidation reaction can be used without any particular purification or removal. Examples of alkanolamines that can be used include mono- and jetanolamines, propatoolamines, and cyclohexylethanolamines, among which ethanolamine (particularly jetanolamine) is preferred. These alkanolamines are usually produced by adding alkylene oxide to ammonia or primary amines and purifying them by steaming or the like. In the present invention, there is no particular need for purification, and a mixture of mono- and dialkanolamines can be used, and trialkanolamine, which is a by-product, can also be used as long as its content is 50% or less. Normal molar ratio of these fatty acids and alkanolamines/! 0. ! r~3, preferably /:
It can be produced by using a ratio of 0.7 to 2.51, particularly preferably /j/-2.

In this reaction, in addition to the amide represented by the general formula, by-products of various esters and unreacted alkanolamines are contained due to the esterification reaction, but they can be used without any problems as long as they are within the above molar ratio range.

Specific compounds include valmitine and sea ethanolamide, stearin and sea ethanolamide, oleic acid mono- and di-ethanolamide and its 161+ coconut oil fatty acid cyclohexylethanolamide, lylunic acid jetanolamide, Examples include ricinoleic acid jetanolamide and alkylene oxide+02-04) adducts of the above compounds.

The rubber composition of the present invention is obtained by blending the above-mentioned alkylolamides with 2 to 10 parts of sulfur as a 10 molar agent to 700 parts by weight of a rubber made from natural rubber, synthetic rubber, or a blend thereof. Sulfur bloom is suppressed by adding it to the rubber composition. Synthetic rubbers in the rubber composition to which alkylolamides are added include synthetic isoprene rubber, styrene-butadiene copolymer rubber, and polybutadiene/ethylene rubber. - Any rubber such as propylene ternary copolymer rubber, polyisobutylene rubber, or a blend thereof, polybutadiene rubber, acrylonitrile rubber, ethylene/propylene copolymer rubber, and butyl rubber can be used. The amount of sulfur blended into the rubber is less than 2 parts by weight per 100 parts by weight of the rubber, and the amount of sulfur blended is 2 to io'H parts by weight. The alkylolamides added to such rubber compositions have appropriate interactions with both minerals, polar substances, and organic materials, and have a suitable interaction with sulfur or moisture in the rubber in the rubber matrix. It is presumed that it has a secret interaction with rubber molecules and causes a kind of solubilization phenomenon for sulfur, but the details of this solubilization phenomenon are not clear, and 170 sulfur reaction, It has almost no effect on the physical properties of the vulcanizate or its contact with the steel cord.

In the present invention, the amount of alkylolamide is 100%
If it is less than 00 parts per part, it will not have the suppressing ability, and if it exceeds 3 parts, it may cause blooming of the alkylolamide itself and affect the vulcanized physical properties. OS~3 parts by weight, more preferably 0.2 to 1 part by weight. Furthermore, when the amount of sulfur blended exceeds 3 parts by weight, it is preferable to add 0.3 parts by weight or more.

Further, for rubbers where adhesiveness is important such as steel cord temporary rubber, it is particularly preferable that the amount added be 0 or less. Sulfur and the alkylolamide compound can be added directly to the rubber, but good results can also be obtained by premixing them with a compounded chemical such as sulfur and then mixing them into the rubber. The mixing method, mixing device, mixing conditions, etc. of the alkylolamide may be the same as those for ordinary compounding agents.The rubber composition of the present invention contains sulfur, which is usually used in the rubber industry, as a compounding agent other than sulfur. Other compounding agents such as vulcanizing agents, vulcanization accelerators, beating aids, anti-aging agents, and reinforcing fillers may be appropriately selected and blended. Examples of these compounding agents include those described in "Synthetic Rubber Handbook" (Tokuniri jO~'17/page), published by Asakura Shoten, July 10, 1960.

The rubber composition of the present invention having the above structure can be widely used as various industrial rubber products such as tires and belts for various vehicles.

The present invention will be explained in more detail using the following examples and comparative examples.

Example 1 A rubber composition shown in Table 2 to which the proboscis shown in Table I1 was added was kneaded and then temporarily placed on a steel cord in a three-roll calender. The three-roll calender was operated at a roll temperature of 20'C and a calender latitude of jOm/min to form a rubber-covered cord layer. The rubber temporary cord layer was rolled up with 8 large mechanical stimulations per cut, left to warp for 2 days, and then photographed after being left for 2 days.
Image analyzer (khtsu - Seisakusho Omnicon)
Sandalwood in which sulfur bloom occurred was measured and the bloom rate relative to the rubber surface was determined. The results obtained are shown in Table 2.

Example 2 The bloom rate of the rubber compositions shown in Table 3 was measured in the same manner as in Example 1. The obtained results are also listed in Table 3.

As shown in Table 2 and Table iJ3, alkylolamides exhibit a strong bloom suppression effect compared to conventional plume prevention agents such as sorbitane in Sitacom compositions containing either ordinary sulfur or insoluble sulfur, especially in the j-day period. It is surprising that the effect lasts even after being left alone.

Example 3 The bloom rate of the rubber compositions shown in Table 4 was measured using the same machine as in Example 1. The obtained results are also listed in Table 4.

From Table 4, it is understood that the rubber composition of the present invention exhibits an excellent plume suppressing effect not only in natural rubber compositions but also in various synthetic rubber compositions.

Claims (1)

[Claims] l, General formula (in the formula, R is an acyl group residue having j to 2 carbon atoms, M is an alkylene group having 2 to 2 carbon atoms, R/ is 10 m 0) nH & or carbon number l - indicates a hydrocarbon group, m is an integer of 1 or more,
A sulfur bloom inhibitor for rubber comprising an alkylolamide compound represented by (n is O or an integer of 1 or more, m+n1111-40). 2. A rubber composition prepared by adding 2 to 10 parts by weight of sulfur as a vulcanization agent to 100 parts by weight of rubber selected from natural rubber, synthetic rubber, or a blend thereof.
The following general formula (in the formula, R is an acyl capture group having 5-J carbon atoms, M is alkylene 4 having 2 to μ carbon atoms, R/ is +M0) n
Indicates a H group or an ashing water curtain with a carbon number of 1 to 2μ, m is 1
or more, n is O or an integer of 1 or more, m+n=/~
A vulcanizable rubber composition with improved sulfur bloom, characterized in that it contains an alkylolamide compound represented by ≠O. 3. The range # of special snoring tuna that is 00OS to 3 parts by weight per 100 parts by weight of violet or rubber of the compound represented by formula 1 above! A vulcanizable rubber composition with improved sulfur bloom according to item 2. Synthetic rubber is synthetic isoprene rubber, styrene-butadiene rubber, and polybutadiene rubber. A DIJ sulfurable rubber with improved sulfur bloom as described in item 2 or 3, which is either ethylene/propylene Sangoyanji rubber or hapolyisobutylene rubber, or a blend rubber thereof. Rubber composition.