JPS5823409B2 - Rubber anti-aging agent - Google Patents

Description

[Detailed description of the invention] The present invention relates to anti-aging agents for rubber.

Generally, amine and phenol compounds are known as anti-aging agents for rubber.

In particular, phenyl-beta-naphthylamine is a typical compound, but its use has recently stopped due to the carcinogenic properties of its raw material, beta-naphthylamine.

Therefore, there is a strong desire to develop a safe anti-aging agent to replace it.

As such compounds, adducts obtained by the Ziels-Alder reaction between a quinone compound and a diene compound, and enol compounds obtained by isomerizing the adducts have been conventionally known.

That is, US Pat. No. 2,379,460 (1945) describes the compound 4a.5.8.8a-tetrahydronaphthoquinone (hereinafter abbreviated as T for tetra, H for hydro, and NQ for naphthoquinone), 1.4.4a.5・8・8a・9
a.10a-octa-hydroanthraquinone (hereinafter, anthraquinone is abbreviated as AQ).

) compound or ZIELS-ALDER (hereinafter abbreviated as DA) of NQ and dienes.

) reaction adducts such as 1,4,4a,9a-THAQ have been proposed as anti-aging agents for rubber, and US Pat. No. 2,456,154 (1948) and US Pat.
No. 87 (1944) specifies a 1,4-dihydronaphthohydroquinone compound or 1,4-dihydroanthrahydroquinone (hereinafter, di is abbreviated as D and anthrahydroquinone is abbreviated as AHQ).

) compounds are also listed as anti-aging agents.

The present inventors conducted a rubber vulcanization test using 1,4,4a,9a-THAQ, which is relatively inexpensive among the above compounds, and 1,4-DHAHQ, which is its isomer (enolized product). I did it.

However, white powder was observed to come out on the surface of the obtained rubber.

This is a so-called blooming phenomenon.

When this blooming occurs, the commercial value of the rubber product is almost completely lost.

The anti-aging effect is also significantly reduced.

Therefore, the present inventors conducted further research in order to eliminate the drawbacks when using these AQ compounds as anti-aging agents.

As a result, these AQ compounds were partially hydrogenated, and at least the double bonds at the 2 and 3 positions were saturated and 1, 2, 3, 4-T
By forming an H ring, blooming is prevented,
Furthermore, they discovered scales with improved anti-aging effects and completed the present invention.

(However, in the above reaction formula, X and n represent the same meanings as the symbols in the general formula above.

) The 1.4-4a.9a-THAQ represents a starting aromatic group, X and n represent an alkyl group and the number of substitutions of the alkyl group, respectively, and n is an integer of O to 4.

] It consists of a rubber anti-aging agent selected from the group of compounds shown below.

That is, the compound of the present invention has at least 1, 2, 3, 4
-TH ring must be formed.

Compounds of the general formula (I> or X) used in the present invention are:
Usually, the D of NQ and butadiene as shown in the following formula
l・4・4a・9a-THAQ obtained by reaction A
The starting material is

As a starting material, a schematic route for synthesizing the compounds of general formulas (1) to 5) is shown below.

As the compound of general formula (I), 1,2,3,4-TH
AHQ or its alkyl substituents such as methyl, ethyl, propyl or butyl, e.g. 2-methyl, 2.3
-dimethyl-1-methyl- or 2-ethyl-substituted 1,2,3,4-THAHQ; general formula (as a river compound, 1,2,3,4-THAQ or an alkyl substituent as above) Compounds having the general formula 1-2, 3-4-.4a and 9a-hexaHAQ or compounds having the general formula 1, 2, 3 and 9a-hexaHAQ, or compounds having the general formula 1, 2, and 3 having the above-mentioned alkyl substituents.・4.4a.9a-hexahydro-10-hydroxyandrone (HEHA)
It is abbreviated as TR.

) or a substituent having an alkyl substituent as described above.

However, the compound of general formula W is considered to be an AHQ compound with the following structural formula, but according to infrared spectral analysis etc., it is considered to be the former structural formula 1 in the solid state.

The compounds of the invention may also be mixtures of compounds kl) to W.

Examples will be described in detail below.

Example 12 (1) ■ 10.0 parts of 4-NQ and 6 to 84 parts of 1,3-butadiene were mixed in ortho-xylene at 120°C under pressure for 4 hours.
After the reaction, the ortho-xylene was concentrated under reduced pressure, cooled, and the crystallized product was filtered.
2.7 parts of HAQ1 (purity 99.8%) 2 was obtained.

(2) l −4・4a −9a −T obtained in (1)
2.12 parts of HAQ in ethanol using palladium-carbon particles as a catalyst at room temperature under pressure (5 kg/cAG)
, 2 moles of hydrogen was absorbed relative to the raw material THAQ.

The catalyst was filtered once and the solvent was distilled off to obtain 2.12 parts of HEHATR.

When this is recrystallized from n-hexane-ethanol solvent, the melting point is 106-107°C, and the characteristic infrared absorption is OH structure 3400bond, c=o structure 31685
cIrL-1, CH2 structure 2950 (lF77L', 2
It was 850CIfL'.

(3) 1-4-4a/9a- obtained in Example (1)
2.12 parts of THAQ was dissolved in palladium-
4 (5 kg/c) at room temperature and under pressure using carbon particles as a catalyst.
fLG) Hydrogen was absorbed in an equal molar amount to the raw material THAQ.

Pass the catalyst once and distill off the solvent to obtain 1, 2, 3, 4, 4a,
9a-hexaHAQ2. I got the IO part.

When this was recrystallized with ortho-xylene, the melting point was 89~
91℃, and the characteristic infrared absorption is c=o structure 1685
cIft', CH2 structure 2940CIIL-1,28
There was 5oCIIL-1.

(4) 1, 4, 4a, 9a- obtained in Example (1)
2.12 parts of THAQ was dissolved in 7 parts of ortho-xylene, and 0.3 parts of para-toluenesulfonic acid was added to enolize it at 100°C for 1 hour, followed by filtration, washing, and drying to obtain 1.4-D.
2.10 parts of HAHQ were obtained.

This 1,4-DHAHQ was mixed with palladium in ethanol.
Using carbon particles as a catalyst, under room temperature and pressure (5 kg/crt
fG ), 1 mole of hydrogen was absorbed by this DHAHQ.

Pass the catalyst once and distill off the solvent to obtain 1,2,3,4-THA.
2.08 parts of HQ was obtained.

The melting point of this product recrystallized with an ortho-xylene-ethanol mixed solvent is 215-216°C (literature value 208-2
16℃), and the characteristic infrared absorption is OH structure 3350
cIrL', CH2 structure 2930C111', 285
It was 0CIIl'.

(5) 1, 2, 3, 4-TH obtained in Example (4)
After oxidizing 2.14 parts of AHQ in ethanol at 80°C for 1 hour while passing air through it, the solvent was distilled off to obtain 1, 2, and 3.
- 2.10 parts of 4-THAQ was obtained.

The melting point of the recrystallized product is 156-157°C (literature value 156-1
58℃), and the characteristic infrared absorption is the C=O structure 165
0CIrL-1, CH2 structure 2950 (m', 2880
cm'.

(6) Some 2-methyl of the compounds synthesized in (Mal) to (5) above (hereinafter, methyl is abbreviated as Me).

) Substituents were synthesized in the same manner as in Examples (1) to 5) using isoprene in place of butadiene.

The structural formula and physical properties of the compound are shown in Table 1. Example 2 The compound of the present invention and a comparative anti-aging agent were each added to synthetic rubber and subjected to a vulcanization test, a stress relaxation test and an ozone deterioration test, and the degree of blooming and performance as an anti-aging agent were compared.

First, the following compounds (indicated by symbols below):

) A... No additives (comparison), B... Zenylubetanaphthylamine (comparative anti-aging agent), C...
・・・・・・1・2・3・4-THAHQ,D・・・・
・1・2・3・4-THAQ, E・・1-2-3・4
-4a -9a-HexaHAQSF・・・・・・HEH
ATR, G...2-Me -1・2 ・3 ・
4-THAHQlH・-・2-Me-1・2・3・4
~THAQ1J...2-Me-HEHATR,
to---1・4・4a・9a-THAQ (comparison),
L...1. - Using 4-DHAHQ (comparison) as an anti-aging agent sample, cross-mixing (according to ASTM D-15) at the following compounding ratios (however, the roll used was 8 x 18 inches in size, rotation ratio 1.18, and rotation speed) i8r, p, m(f), surface temperature 50±5°C), and then vulcanized at 150°C to form a rubber plate and use it as a test piece.

This test piece was tested using a relaxometer in accordance with JISK-6301, at a test temperature of 100°C and an elongation rate of 5.
A stress relaxation test was conducted under the conditions of 0% and preheating time of 30 minutes.

The test results are shown in Table 2.

In addition, although an ozone deterioration test was conducted, no difference was observed between each sample.

As can be seen from Table 2, the compounds of the present invention having a saturated ring at the 2.3-position of the AQ nucleus, C to J, are
Compound K having an unsaturated ring at position 3 (1.44a.9a
-THAQ) and L (1,4-DHAHQ'), whereas K and L caused noticeable blooming, no blooming occurred and rather good results were obtained in the stress relaxation test. .

Furthermore, it was significantly superior to the case of additive-free A, and comparable to conventional anti-aging agents.

Example 3 Natural rubber was subjected to a vulcanization test, a stress relaxation test, and an ozone deterioration test in the same manner as in Example 2, and the degree of blooming and performance as an anti-aging agent were compared.

The same anti-aging agent samples A to Example 2 were kneaded and blended at the following blending ratios (according to ASTM D-15) (however, the rolls used had dimensions of 8 x 18 inches and rotational speeds of 18 r, p, m (
f), the surface temperature is 70°C±5), and then vulcanized at 140°C to form a rubber plate and use it as a test piece.

This test piece was tested using a relaxometer in accordance with JISK-6301, at a test temperature of 100°C and an elongation rate of 5.
A stress relaxation test was conducted under the conditions of 0% and preheating time of 30 minutes.

The test results are shown in Table 3.

In addition, although an ozone deterioration test was conducted, no difference was observed between each sample.

As can be seen from Table 3, as in Example 2, Compounds C to J of the present invention are similar to Comparative Compound K (1.44 a.9
Compared to a-THAQ) and L (1,4-DHAHQ), blooming occurred in K and L, but no blooming occurred, and the results of the stress relaxation test were also rather good.

Furthermore, it was significantly superior to the case of additive-free A, and comparable to conventional anti-aging agents.

Claims (1)

[Claims] 1 In the general formula, X and n represent alkyl and the number of substitutions of the alkyl group, respectively, and n is an integer of 0 to 4. A rubber anti-aging agent selected from the group of compounds represented by ].