JPS5936145A - Cured chloroprene rubber composition - Google Patents

Abstract

PURPOSE:To obtain titled composition of high stability to scorching in the curing process even without any scorch retarder, by first incorporating a 2-iminocycloalkyl dithiocarboxylic acid derivative in a chloroprene rubber followed by rapid curing at low temperature for a short time. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100pts.wt. of a chloroprene rubber with (B) 0.1-3pts.wt. of a 2-iminocycloalkyl dithiocarboxylic acid derivative of formula I (R<1> is H, 1-3C alkyl, or cyclopentyl; R<2> is H, 1-6C alkyl, cyclopentyl, or cyclohexyl; R<3> is H, methyl, or ammonia; n is 2 or 3) or II (R<4> is H, 1-6C alkyl, cyclopentyl, or cyclohexyl) (pref. of low molecular weight, because small incorporation will be enough, therefore economical), followed by carrying out a curing in a conventional manner. Incorporation of a second curing accelerator along with optimum temperature will result in the improvement in the stability to scorching by 50-150% and reduction in the curing time by 10-50%, compared with the case where diethyl thiourea capable of super curing acceleration is applied.

Description

[Detailed description of the invention] This invention relates to chloroprene rubber (hereinafter abbreviated as laJ).

) as a vulcanization accelerator! -This invention relates to a chloroprene rubber vulcanized composition containing an iminocycloargyldithiocarboxylic acid derivative.

In general, OR has excellent ozone resistance, heat resistance, weather resistance, and oil resistance when compared to other diene rubbers, and for this reason, it is used in large quantities in industrial parts as a so-called durable rubber. is where everyone agrees.

However, in order to make the most of such OR characteristics, various additives play a large role, and in particular, the method of using the vulcanization accelerator plays a large role. This effect is also due to the fact that OR has fewer types of vulcanization accelerators than other diene thread rubbers. For example, in diene thread rubber, the vulcanization accelerators include thiazole compounds (such as 2-mercaptobenzothiazole and dibenzothiazolyl disulfide) and sulfenamide compounds (N-cyclohexyl-cobenzothiazolyl sulfenamide, etc.). , N-
oxydiethylene-2-benzothiazolylsulfenamide, etc.), guanidine compounds (/, 3-diphenylguanidine, /, 3-diO=tolylguanidine, etc.)
, thiuram compounds (tetramethylthiuram disulfide, tetramethylthiuram monosulfide, etc.), dithioate salt compounds (zinc dimethyldithiocarbamate, sodium diethyldithiocarbamate, etc.) Vulcanization accelerators that have been most effectively used so far are thiourea compounds (such as ethylenethiourea and diethylthiourea).

However, since the oil shocks of 1999 and 1999, energy and resource conservation movements have gained momentum around the world, and as a result, measures have become urgently needed in the rubber industry as well.

Among these measures, as an energy-saving measure, there is a demand for high-speed vulcanization that shortens the vulcanization time in order to shorten the process time, and in particular to save energy during the vulcanization process.

Generally, high-speed vulcanization increases the vulcanization temperature. ■It is carried out using two methods: using a vulcanization accelerator that has an ultra-fast vulcanization accelerating ability, but for the reason of energy saving mentioned above, the vulcanization time can be shortened without raising the vulcanization temperature. ■Method is desired.

Further, as a resource saving measure, especially with the development of the automobile industry, there is a demand for higher durability of rubber parts. For this reason, rubber parts require more advanced processing, and as the B+I process inevitably becomes more complex, it is necessary to heat the unvulcanized rubber before applying it to a calendar or extruder, or to use an extruder. There is a strong desire for scorch stability of unvulcanized rubber against heat generation in the unvulcanized rubber.

For these purposes, diethylthiourea (hereinafter referred to as [gup
It is abbreviated as J. ) is used. When using EUR,
Although the curing time is considerably shortened, the unvulcanized rubber may undergo IV burn (scorch, SL!orching) during the processing process.
)' It leads to the destruction of the processing machine and forces the interruption of the vulcanization process.

For this purpose, dibenzodeazolyl disulfide and tetramethylthiuram disulfide are generally used as scorch inhibitors, but they lower the crosslink density and lower the tensile stress (Kennari Goda, Synthetic Rubber Processing Technology Complete Book■ Chloroprene Rubber Stock Company Taiseisha Showa Gua Published on 70/20/2020, 2nd QN2r page). In addition, the conventional Tokkai Akira,! ;! ;-/3. Although scorch inhibitors have been proposed in Publication tl'A7, they are not satisfactory. Furthermore, the use of such scorch inhibitors is uneconomical. Therefore, there is a need for a vulcanization accelerator that essentially stabilizes scorch during processing and has ultra-fast vulcanization accelerating properties during vulcanization.

An object of the present invention is to develop and provide a vulcanization accelerator for chloroprene that should meet such demands.

In order to achieve the above object, the inventors conducted intensive research and found that 2-iminocycloalkyldithiocarboxylic acid derivatives have F;
It has been found that it exhibits excellent effects in that it is significantly faster than EUR and its scorch stability during processing is significantly more stable than that of EUR, and based on this knowledge, the present invention has been completed.

The gist of this invention is to provide a chlorobrene compound containing seven or more 2-iminocycloalkyldithiocarboxylic acid derivatives represented by the following general formula [■] or [I[] as a vulcanization accelerator. Rubber vulcanized UiG product.

General Formula [1] General Formula [■] A detailed and specific explanation of the constituent elements of this invention will be described below.

The 2-iminocycloalkyldithiocarboxylic acid derivative used as the vulcanization accelerator for chlorobrene according to the present invention can be produced by a known synthesis method described below. The following are representative examples. That is, those belonging to the general formula [I] include -imy/cyclopentanedithiocarboxylic acid, -methyliminocyclopenkunediocarboxylic acid, 2-ethyliminocyclopenkune dithiocarboxylic acid, and 2-εgc- Butyliminocyclopenkune dithiocarboxylic acid, comethyliminocyclopenkune dithiocarboxylic acid methyl ester.

3-Methyl-2-iminocyclopentanedithiocarboxylic acid.

3-Methyl-2-cyclohexaniminodithiocarboxylic acid.

2-Methyliminocyclohexane dithiocarboxylic acid, 2
-ethyliminocyclohexane dithiocarboxylic acid, 2-
Examples include n-propyliminocyclohexane dithiocarboxylic acid, but are not limited to these compounds.

In addition, as for those belonging to the general formula (1), bis(
, 2-iminocyclopentylthiocarbonyl) disulfide, bis(,2-methyliminocyclopentylthiocarbonyl) disulfide, bis(2-ethyliminocyclopentylthiocarbonyl) disulfide, bis(j
-n-propyliminocyclobentylthiocarbonyl)
Disulfide, bis(+2-5ec-butyliminocyclopentylthiocarbonyl) disulfide, bis(,2
-cyclopentyliminocyclopentylthiocarbonyl) disulfide, bis(λ-cyclohexyliminocyclopentylthiocarbonyl) disulfide, etc., but are not limited to these compounds. Furthermore, it is preferable that a compound having a small molecular weight is economical because it requires a small amount to be added.

The compound belonging to the general formula [I] is Naoaki Fukada.

Kenichi Arai, Tatsuo Takeshima: Synthesis Volume 7 No. 56 Page Otsu 19go (Naoaki Fu
kada, Ken-1chi Arai, Ta
Tsuo Takeshima: 5ynthes
is.

Vol, 7,! ; It can be easily manufactured according to the method of 6 Otsu (/g (11)) and according to the anti-single-core method described in 1.

(An example of the production of comethyliminocyclopentanedithiocarboxylic acid (A), ie, comethyliminocyclopentanedithiocarboxylic acid, is shown below.)

Under ice-cooling, add 1 g (O, 1 mol) of cyclopentanone and carbon disulfide/t to a fourth flask of 0 ml.
, r g (o, /x i, s mol) and further 4
10% monomethylamine aqueous solution is, sg.

(,O,/'; 1.2.0 mol) and water Omt were added, and after reacting for 2 hours at less than /0'O, 2N hydrochloric acid!;
7ml was added. The resulting powder was filtered, washed with water, and then recrystallized from acetone to obtain a yellow-red powder with the desired physical strength. Yield 6g%, melting point /, 24'~/2s'a (literature value: /, 2
Furthermore, the ester chemistry of the target compound (A) in the above reaction formula (1) can be easily produced according to the general esterification reaction described below.

(Object (A)) (Dialkyl object CB) That is, an example of the production of 2-methyliminocyclobenkune dithiocarboxylic acid methyl ester will be shown.

, 200 ml. Water in the fourth flask / O O
ml and arsenium hydroxide λ. g g( o.o.
g mol] and 2-methyliminocyclopentanedithiocarl] was added thereto and dissolved, then cooled with water (10 to 20°C).
and dimethyl sulfate 7.6 gco. 0 mole] was added dropwise to
r + shi 1711 power・<4 Tet.

The formed precipitate was filtered, washed with water, and then recrystallized from isobrohydral alcohol to obtain 6 tons of the desired product as a yellow-red powder. 11 paternity rate 7I 1.9%.

Melting point/lt2~111<z℃ (literature value: lg3~7tl
<z°C) On the other hand, the compound belonging to the general formula []I) is
Naoaki Fukada, Kenichi Arai, Tatsuo Takeshima: Synthesis Volume 7, Page 566, 1910 (
Naoaki Fukada.

Kenichi Arai, Tatsuo Tak
eshima: Synthes-ls y v
ol. 7,'. 4 AA ( / 9 Il'
O): It can be easily produced according to the following reaction formula according to the method of II.

An example of the production of bis(2-methylimie/cyclopentyldiocarbonyl) disulfide is shown below.

Under water cooling, cyclopentanone g, g [α1 mol], carbon disulfide/1. p g
(o, i x /, s mol] and sulfur o, s g (0,
/XO, /zamol] and then add tt.

% monomethylamine/2.1 g (0,/X/
, 7 mol] and water/32. ml of 2N hydrochloric acid was added, stirred at 70°C or less for g hours to react, and then left to stand day and night. ml was added. The resulting powder was filtered, washed with water, and then recrystallized from an aniline/ethanol mixed solvent to obtain the desired product as a yellow powder. Yield j 7.0%, melting point / 7
7.3~lzaO,S℃ (Literature value: 17W~/10℃) Table of the characteristic values of the 2-iminocycloalkyldithiocarboxylic acid derivative according to the present invention -/-/Table 1-/- Shown in 2.

Next, a mode of implementing this invention 6 will be described.

The chloroprene rubber vulcanized compositions of this invention are manufactured according to conventional rubber processing methods. When the 2-iminocycloalkyldithiocarboxylic acid derivative according to the present invention is added to OR as a vulcanization accelerator, the amount added is 0.
O, 1 to 3 parts by weight per 700 parts by weight of R, preferably 0.
It is 3 to 7.3 parts by weight.

In this case, if the amount is less than 0.1 parts by weight, the vulcanization rate decreases significantly and is not practical. On the other hand, if 3 parts by weight or more is added, the scorch speed increases, but the vulcanization rate does not increase, which is uneconomical.

In addition to metal oxides such as zinc oxide, magnesium oxide, and lead oxide, the chloroprene rubber vulcanization composition of the present invention also contains a commonly used vulcanization accelerator for diene rubber,
Antiaging agents, fillers, pigments, plasticizers, and other compounding agents can be added, and sulfur can also be used.

Furthermore, the method of using the 2-iminocycloalkyldithiocarboxylic acid derivative according to the present invention as a vulcanization accelerator is no different from that of conventional vulcanization accelerators for chloroprene. Therefore, vulcanization can be carried out using a method commonly used in conventional OR vulcanization processes, such as press vulcanization, injection vulcanization, etc., and a vulcanization machine.

Next, the effects of this invention will be described.

The 2-iminocycloargyldithiocarboxylic acid derivative according to the present invention has a vulcanization temperature of 1.5% of that of conventional thiourea compound vulcanization accelerators for IJP with other vulcanization accelerators for OR. Compared to FUR, which has ultra-fast vulcanization accelerating properties, the scorch stability (scorch time) determined by the Mooney scorch test is improved by 50 to 750%, and the vulcanization time (t'c (90)
), a remarkable lees characteristic indicating an effect of 10 to 10% reduction in SO was observed.

Hereinafter, the effects of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

Example / Measurement of scorch time and vulcanization time of unvulcanized composition Based on the formulation table in Table 2 below, the compound according to the present invention or a comparative compound was used as a test vulcanization accelerator according to a conventional rubber processing method. ' Knead the specified amount using a kneading roll machine, and use the rotor L according to JISK 6300.
Shape, test temperature/Scorch time was measured at 23°C.

Furthermore, the Japan Rubber Association standard 5RIS 3to2-
/977 (vulcanization test method using IJI + sulfur tester), rheometer vulcanization test (Test made by Toyo Seiki) The results are shown in Table 3.

Table 2 As can be seen from the above examples, when the coiminocycloalkyldithiocarboxylic acid derivative according to the present invention is used as a vulcanization accelerator for CAH, the It is clear that it is a vulcanization accelerator that has no scorch stability and has ultra-fast vulcanization accelerating properties.

Patent Applicant Procedures Amendment 1982/, February 16th, 1981 Commissioner of the Patent Office Kazuo Wakasugi Tonohachi Indication of the case 1981 Patent Application No. 1I/, 4/&7 2, Title of the Invention 3, Make amendments Relationship with patent case Patent applicant! , the number of inventions will increase due to amendment None・−−
'°°-1 7. Contents of amendment (1) Table on page 72 of the specification -/-/, I(r, /3
Correct "isopropyl" in the R' column to "isopropyl".

(2) Set "Loop Prople" in column I of A2/ of the same table to [1'
--Corrected to "Propyl".

that's all 31

Claims (1)

[Scope of Claims] A chloroprene rubber compound comprising seven or more 2-iminocycloalkyldithiocarboxylic acid derivatives represented by the following general formula [I] or (II) as a vulcanization accelerator. Sulfur composition. General formula [1] General formula [11]