GB1599540A - Curable chlorinated elastomer composition - Google Patents

Description

(54) CURABLE CHLORINATED ELASTOMER COMPOSITION (71) We, DAINICHI-NIPPON CABLES, LTD., a corporation organized under the laws of Japan, of No. 8, Nishino-cho, Higashimukaijima, Amagasaki-shi, Hyogo-ken, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to an improvement of curable chlorinated elastomer compositions.

In the United States Patent No. 4,051,078, there is proposed a compound having the general formula: RSxR' wherein R and R' are respectively polyhydroxyaryl group having 6 to 18 carbon atoms and x is zero or an integer of 1 to 4, as an accelerating agent for chlorinated elastomers. However, a chlorinated elastomer composition containing this compound as an accelerating agent has a tendency to scorch somewhat with increasing amount of the compound, and the vulcanisate of the composition does not necessarily have a sufficient resistance to aging.

In Japanese Patent Publication No. 14175/1973 corresponding to the United States Patent Application Serial No. 739,210, there is proposed a curable polychloroprene composition which contains sulphur as a curing agent and a compound such as bis-(1,3-dihydroxyphenyl) sulphide which is included in the above-mentioned compound or tetramethyl thiuram sulphide as an accelerating agent. However, the vulcanisate of the composition has a fairly poor resistance to aging. This is attributable to sulphur employed as a curing agent as seen in Comparative Examples described later.

The present inventors have now found out that, when a chlorinated elastomer is cured by employing not sulphur but a metal oxide as a curing agent and the combination of the above-mentioned specific compound and other compounds such as thiuram sulfides, as an accelerating agent, the above-mentioned problems of the prior art are completely settled and the obtained vulcanisate has a superior resistance to aging as well as well-balanced mechanical properties.

The present invention provides a curable chlorinated elastomer composition comprising a chlorinated elastomer, at least one metal oxide as a curing agent and an accelerating agent comprising (A) at least one compound having the general formula: (HO)mR'SxR2{OH)m, (I) wherein R' and R2 each represent an aromatic ring, x is zero or an integer of 1 to 4, m and m' are each an integer of 2 to 4 and the OH groups may be attached at any position on each aromatic ring, and (B) at least one member selected from the group consisting of: (a) a compound having the general formula:

wherein R3, R4 R5 and R6 are each alkyl, aryl or aralkyl, and R3 and R4 or R5 and R6 may be linked to each other to form an alkylene group, and y is an integer of 1 to 4 (b) a compound having the general formula::

wherein R7 and R8 are each an aryl group or a guanidino moiety -C(=NH)- NHR9 (R9 is hydrogen atom or aryl group) or a salt thereof, (c) a compound having the general formula:

wherein R'O, R", R12 and R'3 are each a hydrogen atom, alkyl, aryl or thiazolyl group, (d) a compound having the general formula:

wherein R'4 is a bivalent organic group and M1 is hydrogen atom, metal,

(z is an integer of 1 to 4 and R'4 is the same as defined above), or a monovalent organic group other than an amino group; or the corresponding amine salts.

(e) a compound having either of the general formulae:

wherein R15, R16, R17 and R'8 are each an alkyl, aralkyl, aryl or cycloalkyl group and R'5 and R16 or R17 and R18 may be linked to each other to form an alkylene group, M2 is metal, and n is an integer of 1 to 5 corresponding to the valency of the metal, (f) a compound having the general formula:

wherein R'9 and R20 are each a hydrogen atom, alkyl or cycloalkyl group and the group

may be unsubstituted or substituted morpholino group, (g) a compound having either of the general formulae:

wherein R2' is alkyl group, M3 is sodium or zinc and p is an integer of 1 or 2, (h) an aldehyde-amine condensation product, and (i) a compound having the general formula:: R22S-S-R23 (XI) wherein R22 and R23 are each an alkyl, aryl, aralkyl, acyl or morpholino group, the amount of the ingredient (B) being 0.05 to 50 parts by weight per 1 part by weight of the ingredient (A).

Examples of the chlorinated elastomer employed in the present invention include polychloroprene, epichlorohydrin rubber, chlorinated polyethylene and chlorosulphonated polyethylene. Polychloroprene is particularly preferred.

Suitable examples of the polychloroprene are polychloroprenes unmodified with sulphur in which sulphur is not employed in the course of preparing polychloroprene per se or is not added to polychloroprene obtained in a raw rubber state. Typical examples of such polychloroprenes are W- and T-type polychloroprenes such as "Neoprene W", "Neoprene WRT" and "Neoprene TW", etc.

The curing agent employed in the present invention is a metal oxide. Examples of the metal oxide are oxides of metals of Group II of the Periodic Table such as beryllium, magnesium, zinc and calcium, metals of Group IV of the Periodic Table such as titanium, tin, zirconium and lead, metals of Group V of the Periodic Table such an antimony and vanadium, metals of Group VI of the Periodic Table chromium, molybdenum and tungsten, and metals of Group VIII of the Periodic Table such as iron, nickel and cobalt. Oxides of zinc, magnesium, calcium, titanium, antimony and lead are particularly preferred. Those metal oxides may be employed alone or in combination. The amount of the metal oxide employed is generally 2 to 40 parts by weight, particularly 5 to 25 parts by weight per 100 parts by weight of the chlorinated elastomer.Even though the curing agent employed in the present composition is the metal oxide, sulphur which is present in an amount of not more than 1 part by weight per 100 parts by weight of the chlorinated elastomer does not give any undesirable result.

In the present invention, it is essential to employ the combination of the ingredient (A) and the ingredient (B) selected from the compounds (a) to (i) as an accelerating agent employed with a metal oxide as a curing agent in curing the above-mentioned chlorinated elastomers.

Suitable examples of the compound of the general formula (I) employed as the ingredient (A) are those in which the polyhydroxyaryl groups represented by R1(OH)rn or R2--(OH),. are groups derived from polyhydroxybenzenes such as resorcinol, catechol, pyrogallol, phloroglucinol and hydroquinone, polyhydroxynaphthalenes having hydroxyl groups at 1,3-, 1,5-, 1,6-, 2,3-, 2,6- or 2,7positions, or polyhydroxyanthracenes having hydroxyl groups at 1,2-, 1,4, 1,4,5,8positions, and x is zero or an integer of 1 to 4, that is, bi(polyhydroxyaryl) or di(polyhydroxyaryl) mono-, di-, tri- or tetra-sulphide. Those compounds may be employed alone or as mixtures thereof.More suitable examples of the compound of the general formula (I) are those in which one or both of the polyhydroxyaryl groups represented by R1(OH)rn or R2OH)rn are groups derived from dihydroxybenzenes such as catechol, hydroquinone and resorcinol, and the derivatives of foregoing dihydroxybenzenes in which I to 3 hydrogen atoms on the benzene ring are substituted by other organic group having 1 to 8 carbon atoms such as carboxyl, alkyl, alkenyl, alkoxy, carboalkoxy or carboxylic amide group, or amine group or halogen atom, and x is 1 to 2.

Some examples of the compound of the general formula (I) and the process for preparing them are described in the United States Patent No. 4,051,078 mentioned previously.

The compound of the general formula (I) can be prepared by various kinds of processes but preferably prepared by (1) a process in which 1.8 to 2.2 moles of a corresponding polyhydroxy aromatic compound is allowed to react with I mole of sulphur dichloride in an organic solvent or (2) a process in which 1.8 to 3 moles of a corresponding polyhydroxy aromatic compound is allowed to react with 1 mole of sulphur monochloride in an organic solvent. Each reaction of the processes ( I ) and (2) is effected by agitating the reactants in an organic solvent for I to 12 hours. The end point of the reaction can be determined by monitoring the progress of the reaction by thin-layer chromatography. In case of need, the reaction mixture may be cooled for reducing the reaction rate or heated for accelerating the reaction rate.

The reaction product of polyhydroxy aromatic compounds and sulphur monoor di-chloride which is prepared by the above-mentioned process may also be employed in the present invention as the ingredient (A) in purified or crude state.

Preferred reaction products are those which are obtained by reacting the reactants at a temperature of -10" to 800C. in an organic solvent such as methanol, ethanol, diethyl ether, acetone or tetrahydrofuran.

The ingredient (B) employed in the present invention consists of one or more compounds selected from the compounds (a) to (i).

The compound (a) is thiuram sulfides represented by the general formula (II).

Suitable examples of the compound (a) are those in which R3, R4, R5 and R6 are alkyl group having not more than 5 carbon atoms, aralkyl group having not more than 8 carbon atoms or aryl group having not more than 8 carbon atoms.

respectively, or R3 and R4 or R5 and R6 are linked each other to form alkylene group having not more than 10 carbon atoms, and y is an integer of 1 to 4. Typical examples of the compound (a) are tetramethylthiuram disulphide (TMTD).

tetraethylthiuram disulphide (TETD), tetramethylthiuram monosulphide (TMTM ) tetrabutylthiuram disulphide (TBTD), dipentamethylenethiuram tetrasulphide (DPMTT), N,N'-dimethyl-N,N'-diphenylthiuram disulphide (DMDPTD), tetrabutylthiuram monosulphide (TBTM), N,N'-diethyl-N,N'-diphenylthiuram disulphide (DEDPTD), dipentamethylenethiuram disulphide (DPMTM), tetraethylthiuram monosulphide (TETM) and dipentamethylenethiuram monosulphide (DPMTM). TMTD, TMTM, TETD and TBTD are particularly preferred. Those compounds may be employed alone or in combination.

The compound (b) is guanidines represented by the general formula (III) and their salts. Suitable examples of the compound (b) are those in which R7 and R6 are phenyl, tolyl, xylyl or guanidino moiety, respectively, and their salts such as acetates, phthalates and dicatechol borates. Typical examples of the compound (b) are N,N'-diphenylguanidine (DPG), N,N'-di-o-tolylguanidine (DTG), otolylbiguanide (BG), di-o-tolylguanidine salt of dicatechol borate (PR), diphenylguanidine phthalate (DPGP), triphenylguanidine (TPG), phenyl tolyl xylyl guanidine (PTXG) and diphenylguanidine acetate (DPGA). DPG, DTG, BG and PR are particularly preferred. Those compounds may be employed alone or in combination.

The compound (c) is noncyclic thioureas represented by the general formula (IV). Suitable examples of the compound (c) are those in which R10, R1', R12 and R13 are hydrogen atom, alkyl group having not more than 12 carbon atoms, aryl group having not more than 10 carbon atoms or thiazolyl group, respectively.

Typical examples of the compound (c) are thiocarbanilide, 1 ,3-bis(2- benzothiazolylmercapto)urea, 1, 3-diethylthiourea (EUR), 1,3-dibutylthiourea, dimethylethylthiourea, trimethylthiourea (TMU), di(o-tolyl)thiourea, tetramethylthiourea and dilaurylthiourea. EUR and TMU are particularly preferred. Those compounds may be employed alone or in combination.

The compound (d) is thiazoles represented by the general formula (V) and their salts. Suitable examples of the compound (d) are those in which R'4 is ophenylene and their amine salts. Typical examples of the compound (d) are morpholinodithio)benzothiazole (MDB), 2-mercaptobenzothiazole (MB), dibenzothiazyl disulphide (DM), 2-(2',4'-dinitrophenylthio)benzothiazole, 2mercaptobenzothiazole cyclohexylamine salt, zinc salt of 2-mercaptobenzothiazole (MZ), copper salt of 2-mercaptobenzothiazole (MCu), N,N-diethylthiocarbamoyl 2-benzothiazyl sulphide, 2-benzothiazylthiobenzoate, 2-(2,6-dimethyl-4morpholinothio)benzothiazole and 1,3-bis(2-benzothiazylmercaptomethyl)urea.

MDB, MB, DM and MZ are particularly preferred. Those compounds may be employed alone or in combination.

The compound (e) is dithiocarbamates represented by the general formula (VI) or (VII). Suitable examples of the compound (e) are those in which each of the organic groups represented by R'5, R16, R17 and R18 has not more than 10 carbon atoms and M2 is Na, K, Zn, Pb, Bi, Cd, Te, Se, Fe or Cu.Typical examples of the compound (e) are copper dimethyldithiocarbamate (TTCu), ferric dimethyldithiocarbamate (TTFe), bismuth dimethyldithiocarbamate, zinc dimethyldithiocarbamate (PZ), selenium dimethyldithiocarbamate, potassium dimethyldithiocarbamate, sodium dimethyldithiocarbamate, nickel diethyldithiocarbamate (NEC), tellurium diethyldithiocarbamate (TEG), cadmium diethyldithiocarbamate, zinc diethyldithiocarbamate (EZ), sodium diethyldithiocarbamate, sodium di-n-butyldithiocarbamate, potassium di-nbutyldithiocarbamate, zinc di-n-butyldithiocarbamate (BZ), nickel di-nbutyldithiocarbamate (NBC), lead ethylphenyldithiocarbamate (PE), zinc ethylphenyldithiocarbamate (PX), piperidine pentamethylenedithiocarbamate, sodium pentamethylenedithiocarbamate, lead pentamethylenedithiocarbamate, pipecolin pipecolyl dithiocarbamate, zinc dibenzyldithiocarbamate, Ncyclohexylethylammonium cyclohexylethyldithiocarbamate and Npentamethyleneammonium pentamethylenedithiocarbamate (PPD). PZ, TTCu, TEG and NBC are particularly preferred. Those compounds may be employed along or in combination.

The compound (f) is 2-benzothiazyl sulphenamides represented by the general formula (VIII). Suitable examples of the compound (f) are those in which R'9 and R20 are hydrogen atom, alkyl group having not not more than 10 carbon atoms, cycloalkyl group having not more than 10 carbon atoms or the group

is unsubstituted or substituted morpholino group. Typical examples of the compound (f) are N - cyclohexyl - 2- benzothiazylsulphenamide (CZ), N oxydiethylene - 2- benzothiazylsulphenamide, N,N - dicyclohexyl - 2benzothiazylsulphenamide, N - t - butyl -2 - benzothiazylsulphenamide (NS), N t - octyl - 2 - benzothiazylsulphenamide, N,N - diisopropyl - 2 benzothiazylsulphenamide (PSA) and 2 - (2,6 - dimethyl - 4 morpholinothio)benzothiazole. CZ, NS and PSA are particularly preferred. Those compounds may be employed alone or in combination.

The compound (g) is xanthates and their salts represented by the general formula (IX) or (X). Suitable examples of the compound (g) are those in which R2' is alkyl group having not more than 10 carbon atom and p is an integer of 1 to 2.

Typical examples of the compound (g) are zinc dibutylxanthate (ZBX), zinc isopropylxanthate, sodium isopropylxanthate, dibutylxanthogen disulphide (CPB) and zinc diethylxanthate. ZBX and CPB are particularly preferred.

The compound (H) is aldehyde-amine condensation products. Suitable examples of the compound (h) are condensation products of one or more aldehydes having not more than 10 carbon atoms such as aliphatic aldehydes, and ammonia, or one or more amines having not more than 10 carbon atoms such as primary aliphatic amines and anilines. Typical examples of the compound (h) are condensation products of butyraldehyde and aniline, butyraldehyde and butylamine, butyraldehyde and butylideneaniline, formaldehyde and p-toluidine (FP), heptaldehyde and aniline, acetaldehyde and ammonia (AC), butyraldehyde and formaldehyde and ammonia, butyraldehyde and acetaldehyde and aniline, and formaldehyde and ammonia (hexamethylenetetramine). FP and AC are particularly preferred.

The compound (i) is disulphides represented by the general formula (XI).

Suitable examples of the compound (i) are those in which each of the organic groups represented by R22 or R23 has not more than 15 carbon atoms. Typical examples of the compound (i) are dimorpholino disulphide, alkyl phenyl disulphides such as n-butyl phenyl disulphide, dialkyl disulphides such as di-n-amyl disulphide, bis(y-hydroxypropyl) disulphide, ethyl t-butyl disulphide, ,a- dithiodipropionate and P,P-dithiodipropionate, diaryl disulphides such as diphenyl disulphide, ditolyl disulphide, dixylyl disulphide, bis(4-aminophenyl) disulphide, bis(2-aminophenyl) disulphide and bis(o-benzamidophenyl) disulphide, bis(o-, mand p-nitrophenyl) disulphide, and dibenzoyl disulphide. Dimorpholino disulphide and the diaryl disulphides are particularly preferred. Those compounds may be employed alone or in combination.

The accelerating agent employed in the present invention is composed of 1 part by weight of the ingredient (A) and 0.05 to 50 parts by weight, particularly 0.2 to 20 parts by weight of the ingredient (B) consisting of at least one compound selected from the compounds (a) to (i). When the amount of the ingredient (b) is not less than 0.5 part by weight, particularly not less than I part by weight per 1 part by weight of the ingredient (A), the obtained mixture facilitates handling because the mixture is not so viscous or tacky in contrast to the-accelerating agents described in the United States Patent No. 4,051,078 mentioned previously which are almost resinous. In some cases, the accelerating agent in the present invention is obtained as a powder.Preferably the accelerating agent is composed of 1 part by weight of the ingredient (A), 0.03 to 25 parts by weight, particularly 0.1 to 10 parts by weight of the compound (a) and 0.02 to 25 parts by weight, particularly 0.1 to 10 parts by weight of at least one compound selected from the compounds (b) to (i).

In preparing the chlorinated elastomer composition of the present invention the individual ingredients for the accelerating agent may be incorporated separately or at the same time in desired amounts to a chlorinated elastomer by means of mixing apparatus such as roll mill or Banbury mixer. Alternatively, the individual ingredients may be premixed each other before incorporation to a chlorinated elastomer. The method for preparing such a premixture is not limited.

For instance, the premixture may be prepared in a dry state or a wet state by dissolving the ingredients in an appropriate solvent.

The premixture mentioned above is preferably prepared by the following methods: (1) To a reaction mixture obtained by reacting the polyhydroxy aromatic compound with sulphur mono- or di-chloride in an organic solvent, desired amounts of the compound (a) and/or at least one compound selected from the compounds (b) to (i) are added and mixed. The solvent is then evaporated under an atmospheric or reduced pressure to give a premixture as the accelerating agent. (2) The premixture obtained in (1) is further washed with water several times, filtered and dried. (3) The reaction mixture mentioned in (1) is once poured into water and allowed to stand.After removing the supernatant water layer, desired amounts of the compound (a) and/or at least one compound selected from the compounds (b) to (i) are added to the remaining organic layer, thoroughly mixed and dried under an atmospheric or reduced pressure. (4) If necessary, methanol is added to the organic layer obtained in (3) in order to make it into a solution. Into the solution are added desired amounts of the compound (a) and/or at least one compound selected from the compounds (b) to (i). The resultant is agitated and then mixed with a large amount of water to give a precipitate. The precipitate is filtered and dried.

The accelerating agent prepared according to the above-mentioned processes ( I ) to (4) has the following advantages: The individual ingredients of the accelerating agent act in a close cooperation with one another in a chlorinated elastomer. As a result, the synergism of the ingredients is markedly exhibited. The dispersing properties of the individual ingredients and markedly improved and the ingredients are homogeneously dispersed into a chlorinated elastomer.

In the curable chlorinated elastomer composition of the present invention, the accelerating agent is employed in an amount of 0.1 to 30 parts by weight, particularly 0.5 to 10 parts by weight per 100 parts by weight of the chlorinated elastomer mentioned previously.

The composition of the present invention characterized by employing the combination of the metal oxide and the above-mentioned accelerating agent as a curing system shows improvements in scorching behavior, curing rate and resistance to aging.

In the composition of the present invention, any other additives usually employed for rubbers may be incorporated, including antioxidants, scorch inhibitors, reinforcing agents such as carbon black, processing aids, mineral fillers, processing oils, waxes, lublicants and pigments. The additives also may be preliminarily mixed with the accelerating agent.

As mentioned previously, the present invention has overcome some disadvantage of the sulphur cured polychloropropene vulcanisates of the prior art owing to the presence of sulphur. However, there is allowed the presence of a small amount of sulphur, for instance, less than 1 part by weight, preferably less than 0.5 part by weight per 100 parts by weight of the chlorinated elastomer without decreasing the usefulness of the present invention.

The composition of the present invention is prepared by adding the desired amounts of the metal oxide, the acceterating agent and, if necessary, other additives, separately or at the same time, or a mixture obtained by preliminarily mixing the desired amounts of foregoing materials, to the chlorinated elastomer, and uniformly blending the resultant by means of a conventional rubber mixing apparatus such as a roll mill or Banbury mixer.

The obtained composition is preferably cured at 100 to 220"C for 5 to 120 minutes. The curing may be carried out under an atmospheric pressure or at a pressure of 3 to 150 kg/.cm2.

The curable chlorinated elastomer composition of the present invention is suitable for producing a variety of products including electric cables.

The present invention is more specifically described and explained by means of the following Examples, in which "parts" indicates parts by weight.

Reference Example I. Preparation of compounds as the ingredient (A) Preparation-l Into a solution of 270 g. of resorcinol in 3 liters of anhydrous diethyl ether was added 165 g. of sulphur dichloride. The mixture was agitated at 0 to 50C. for 3 hours. After the completion of the reaction, diethyl ether was evaporated and the residue was poured into an ice-cold water with agitating to give a white precipitate.

The precipitate was filtered and dried to give a white powdery product having a melting point of 161" to 1630C. in 40% yield. The product was identified as 2,2',4',4'-tetrahydroxydiphenyl sulphide.

Preparation-2 The same procedures as in Preparation-l except that 135 g. of catechol and 135 g. of hydroquinone were employed instead of resorcinol were repeated to give a pale yellow sirupy product in 84% yield.

Preparation-3 Into a solution of 50 g. of catechol in 100 ml. of methanol was added 24.5 g. of sulphur monochloride. The mixture was agitated below 45"C. for 3 hours. After the completion of the reaction, the reaction mixture was allowed to stand at a room temperature for 12 hours and then methanol was evaporated under a reduced pressure. The obtained sirupy residue was washed with 100 ml. of water and dried under a reduced pressure below 50"C. to give ayellow caramel-like product in 85% yield.

Preparation-4 The same procedures as in Preparation-3 except that 50 g. of resorcinol was employed instead of catechol were repeated to give a yellow caramel-like product in 90% yield.

Preparation-5 The same procedures as in Preparation-3 except that 50 g. of hydroquinone was employed instead of catechol were repeated to give a yellow caramel-like product in 81% yield.

Preparation-6 The same procedures as in Preparation-3 except that 56 g. of pyrogallol was employed instead of catechol were repeated to give a light brown viscous liquid in 73% yield.

Preparation-7 The same procedures as in Preparation-3 except that 72 g. of 2,3dihydroxynaphthalene was employed instead of catechol were repeated to give a brown sirupy product in 69% yield.

Preparation-8 Into a solution of 25 g. of hydroquinone in 50 ml. of methanol was added 12.2 g. of sulphur monochloride. The mixture was agitated below 45"C. for 2 hours. Into the resulting reaction mixture were added a solution of 25 g. of catechol in 50 ml. of methanol and 12.2 g. of sulphur monochloride. The mixture was also agitated below 45"C. for 2 hours. After the completion of the reaction, the reaction mixture was allowed to stand at a room temperature for 12 hours and then methanol was evaporated. The residue was washed with water and dried to give a pale yellow, finely divided product in 87% yield.

II. Preparation of premixed accelerating agents Preparation-9 30 g. of the reaction product obtained in Preparation-3 was dissolved into 300 ml. of methanol. To the solution were added 15 g. of diphenylguanidine and 168 g.

of tetramethylthiuram sulphide. The mixture was then vigorously agitated to give a slurry. Methanol was evaporated under a reduced pressure to give a pale yellowish white powder as the premixed accelerating agent in theoretical yield.

r reparation- 10 Into the slurry obtained in Preparation-9 was added 2 liters of water to give a precipitate. The precipitate was filtered and air-dried to give a pale yellowish white powder as the premixed accelerating agent in nearly theoretical yield.

Preparation-ll to 24 The same procedures as in Preparation-9 or Preparation-lO were repeated to give the premixed accelerating agents composed of the ingredients as shown in Table 1.

TABLE I Ingredient (A) Compound (a) Compounds (b) to (i) Preparation No. Mixing method Kind Parts Kind Parts Kind Parts 11 Preparation-9 Preparation-1 30 - DM 70 12 " " 30 TMTD 70 13 " Preparation-3 30 - CZ 70 14 Preparation-10 " 30 DPMTT 70 TEG 5 15 " " 30 TBTD 100 PZ 5 16 " " 30 TMTD 70 TTCu 10 17 Preparation-9 " 30 TETD 50 CPB 3 18 " Preparation-8 30 - Morpholino 30 disulphide 19 " " 30 TMTD 60 BG 10 20 " " 30 TMTD 100 TMU 10 21 Preparation-10 Preparation-2 30 DPMTT 50 FP 5 22 " Preparation-4 30 TBTD 50 NBC 5 23 " Preparation-5 30 DMDPTD 50 PPD 5 24 " Preparation-6 30 TMTD 100 PZ 5 Examples 1 to 38 and Comparative Examples 1 to 6 Individual rubber compositions were prepared by blending a composition having the following base formulation with the metal oxides as the curing agent and the ingredients (A) and the compounds (a) to (i) as the ingredients of the accelerating agent or the premixed accelerating agents as shown in Tables 2 to 3 by means of a roll mill at a room temperature for 10 minutes. In Tables 2 to 3. "parts indicates parts per 100 parts of polychloroprene.

Base Formulation Ingredient Parts Neoprene W (E. I. Du Pont de Nemours & Co.) 100 Dixie clay (R. T. Vanderbilt Co., Inc.) 60 HAF carbon black 25 Processing oil (SONIC R-1000; sp. gr. 0.93; viscosity 20 cSt; Nippon Kogyo Ltd.) 10 Stearic acid Microcrystalline wax 1 Antioxidant DDA (Bayer AG.) To estimate the curing behavior of the obtained rubber compositions.

rheometer torque values after 5 and 20 minutes and maximum torque of each composition were measured by using an Oscillating Disk Rheometer (ODR manufactured by Toyoseiki Seisakusho, Ltd.) with a disk sample of 30 mm. in diameter at a temperature of 1500C.

Each composition was press-cured under a pressure of 100 kg./cm.2 at 1500C.

for 30 minutes to give a cured rubber sheet having a thickness of about 2 mm.

Modulus at 200% elongation, tensile strength and elongation were measured with Japanese Industrial Standard No. 3 dumbbell test pieces prepared from the cured sheet according to the provision of Japanese Industrial Standard K 6301.

The cured rubber sheet was aged at 1200C. for 98 hours in an oven. Elongation after aging was measured in the same manner as described above. Retention of elongation was calculated according to the following equation: Elongation after aging Retention of elongation (%)= x100 Elongation at initial The results are shown in Table 4.

TABLE 2 Compounds (a) to (i) Metal oxide Ingredient (A) or sulphur Kind Parts Kihd Parts Kind Parts Com. ZnO 5 Ex. I MgO 4 Com. ZnO 5 Preparation-3 1.0 Ex.2 MgO 4 Com. ZnO 5 Preparation-7 1.0 Ex. 3 MgO 4 Com. ZnO 5 Preparation-4 1.0 Sulphur 3 Ex. 4 MgO 4 Com. ZnO 5 Preparation-3 1.0 Sulphur 3 Ex. 5 MgO 4 Com. ZnO 5 Preparation-3 0.3 Sulphur 3 Ex.6 MgO 4 TMTD 0.7 Ex.I ZnO 5 Preparation-l 0.5 TMTD 1.5 MgO 4 Ex. 2 ZnO 5 Preparation-l 0.5 TMTM 1.5 TiO2 Ex. 3 ZnO 5 Preparation-l 0.4 TMTD 1.2 Fe2O3 3 DTG 0.1 Ex. 4 ZnO 5 Preparation-2 0.4 TMTD 1.2 Pb2O3 5 BG 0.1 Ex. 5 ZnO 5 Preparation-3 0.5 DM 1.5 Sb2O3 6 EUR 0.1 Ex. 6 ZnO 5 Preparation-4 0.3 TMTD 1.0 MgO 4 TMU 0.3 Ex. 7 ZnO 5 Preparation-5 1.0 MDB 0.5 MgO 4 Ex. 8 ZnO 5 Preparation-6 0.3 PZ 0.2 MgO 4 TMTD 1.0 Ex. 9 ZnO 5 Preparation-7 0.5 NBC 0.2 MgO 4 TBTD 1.5 Ex. 10 ZnO 5 Preparation-8 1.0 CZ 1.0 MgO 4 NS 0.2 Ex. 11 TiO2 5 Preparation-3 0.5 CPB 0.1 ZnO 5 TMTD 1.2 Ex. 12 ZnO 5 Preparation-3 0.5 ZBX 0.1 MgO 4 TMTD 1.2 Ex. 13 CaO 2 Preparation-3 0.5 DPMTT 1.0 ZnO 5 AC 0.5 Ex. 14 ZnO 5 Preparation-4 0.5 Morpholino 1.5 MgO 4 disulphide Ex. 15 ZnO 5 Preparation-3 0.5 TTFe 0.1 Sb2O3 6 TMTD 1.0 Ex. 16 ZnO 5 Preparation-l 0.5 TMTD 1.5 CaO 2 Ex. 17 ZnO 5 Preparation-2 0.5 TMTD 1.0 TiO2 5 Ex. 18 ZnO 5 Preparation-2 0.5 TETD 1.0 TiO2 5 Ex. 19 ZnO 5 Preparation-3 0.25 TMTM 1.4 MgO 5 Ex.20 ZnO 5 Preparation-3 0.25 TBTD 1.4 MgO 5 Ex.21 ZnO 5 Preparation-4 0.25 DPMTT 1.4 Fe3O3 6 Ex. 22 ZnO 5 Preparation-5 1.0 DMDPTD 1.2 Pb2O3 3 TABLE 3 Metal oxide Premixed accelerating agent Kind Parts Kind Parts Kind Parts Ex. 23 ZnO 5 MgO 4 Preparation-9 1.5 Ex. 24 ZnO 5 MgO 4 Preparation-lO 1.5 Ex. 25 ZnO 5 MgO 4 Preparation-ll 2.0 Ex. 26 ZnO 5 MgO 4 Preparation-12 2.0 Ex. 27 ZnO 5 MgO 4 Preparation-13 2.0 Ex. 28 ZnO 5 MgO 4 Preparation-14 1.5 Ex.29 ZnO 5 MgO 4 Preparation-15 1.5 Ex. 30 ZnO 5 MgO 4 Preparation-16 1.5 Ex. 31 ZnO 5 MgO 4 Preparation-17 2.0 Ex. 32 ZnO 5 MgO 4 Preparation-18 2.0 Ex. 33 ZnO 5 MgO 4 Preparation-19 1.5 Ex. 34 ZnO 5 MgO 4 Preparation-20 1.5 Ex. 35 ZnO 5 CaO 2 Preparation-21 1.5 Ex. 36 ZnO 5 MgO 4 Preparation-22 1.5 Ex. 37 ZnO 5 MgO 4 Preparation-23 2.0 Ex. 38 ZnO 5 MgO 4 Preparation-24 2.0 TABLE 4 ODR Torque (Kg.-cm.) Modulus at Tensile Retention of 200 elongation strength Elongation elongation T5 T20 Tmax (kg./mm.2) kg./mm.2) (O/o) (O) Com. Ex. l 4 11 17 0.22 0.70 760 14 Com.Ex.2 15 32 38 0.78 1.39 550 45 Com. Ex. 3 11 36 39 0.79 1.20 580 40 Com.Ex. 4 11 32 36 0.56 1.31 620 23 Com.Ex.5 15 38 42 0.78 1.40 500 28 Com.Ex.6 11 50 62 0.79 1.46 550 22 Ex. 1 10 44 58 0.87 1.64 520 69 Ex. 2 14 50 60 0.72 1.55 490 70 Ex.3 10 48 52 0.69 1.50 540 62 Ex.4 10 44 55 0.78 1.50 510 65 Ex.5 10 45 57 0.68 1.51 550 62 Ex.6 16 49 60 0.70 1.55 530 60 Ex. 7 15 50 54 0.80 1.52 485 62 Ex.8 15 58 64 0.88 1.60 490 68 Ex.9 14 58 62 0.81 1.62 455 69 Ex. 10 16 44 49 0.62 1.50 525 61 Ex.ll 12 57 60 0.72 1.59 500 69 Ex. 12 14 52 58 0.73 1.55 520 70 Ex. 13 16 56 61 0.80 1.59 495 69 Ex. 14 14 52 56 0.71 1.53 520 64 Ex. 15 15 53 58 0.75 1.55 520 60 Ex.16 15 49 60 0.80 1.60 530 64 Ex. 17 12 40 55 0.70 1.50 535 62 Ex.18 10 37 53 0.69 1.52 520 65 Ex.19 17 47 55 0.71 1.57 520 68 Ex. 20 18 45 54 0.72 1.55 540 67 Ex.21 11 40 52 0.71 1.51 535 61 Ex. 22 13 44 52 0.82 1.54 490 64 Ex.23 14 59 62 0.77 1.64 500 70 Fx. 24 13 56 60 0.71 1.60 525 69 Ex.25 16 45 60 0.87 1.61 470 63 Ex. 26 15 56 63 0.80 1.69 490 71 Ex.27 16 47 58 0.88 1.50 505 62 Ex.28 14 53 60 0.76 1.51 520 65 Ex. 29 12 48 59 0.71 1.53 525 66 Ex.30 12 49 59 0.73 1.50 510 64 TABLE 4 (cont.) ODR Torque (Kg.-cm.) Modulus at Tensile Retention of 200 200 elongation strength Elongation elongation T5 T20 Tmax (kg./mm.2) kg./mm.2) (%) (%) Ex.31 16 48 55 0.76 1.55 505 65 Ex.32 14 55 61 0.82 1.61 470 70 Ex.33 16 50 55 0.78 1.54 500 63 Ex.34 13 49 56 0.71 1.52 520 62 Ex.35 12 44 51 0.76 1.56 560 61 Ex.36 14 49 56 0.69 1.50 555 64 Ex.37 16 58 62 0.80 1.61 490 68 Ex.38 15 59 61 0.82 1.63 515 62 Examples 39 to 43 and Comparative Examples 7 to 8 Individual rubber compositions were prepared by blending a composition having the following base formulation with the ingredient (A) and the ingredient (B) selected from the compounds (a) to (i) as the ingredients of the accelerating agent or the premixed accelerating agent as shown in Table 5 by means of a roll mill at a room temperature for 20 minutes. In Table 5, "parts" indicates parts per 100 parts of polychloroprene.

Base Formulation Ingredient Parts Neoprene TW (E. I. Du Pont de Nemours & Co.) 100 Dixie clay (R. T. Vanderbilt Co., Inc.) 50 SRF carbon black 40 Processing oil (SONIC R-1000; sp.gr. 0.93; Viscosity 20 cSt; Nippon Kogyo Ltd.) 15 Zinc oxide 5 Magnesium oxide 2 Stearic acid 1 Microcrystalline wax 1 Antioxidant DDA (Bayer AG.) 1 Each composition was press-cured under a pressure of 100 kg./cm.2 at 1500C.

for 30 minutes to give a cured rubber sheet having a thickness of about 2 mm.

Modulus at 200% elongation, tensile strength and elongation were measured with the cured rubber sheet in the same manner as in Examples 1 to 38.

The cured rubber sheet was aged at 1000C. for 70 hours. Retention of elongation was determined in the same manner as in Examples 1 to 38. Retention of tensile strength was also determined according to the following equation: Tensile strength after aging Retention of tensile strength (%)= x 100 Tensile strength at initial The results are shown in Table 5.

TABLE 5 Retention Accelerating agent Modulus at Tensile of tensile Retention of 200% elongation strength Elongation strength elongation Kind Parts (kg./cm.2) (kg.cm.2) (%) (%) (%) Com. Preparation-3 1.5 0.63 1.49 450 112 60 Ex.7 Com. Preparation-7 1.5 0.64 1.40 440 119 59 Ex.8 Ex.39 Preparation-11 1.5 0.89 1.60 390 95 86 Ex.40 Preparation-12 1.5 0.72 1.62 420 98 82 Ex.41 Preparation-13 1.5 0.79 1.60 410 99 84 Ex.42 Preparation-3 1.5 0.83 1.64 380 101 80 TMTD Ex.43 Preparation-3 2.0 0.86 1.69 320 100 89 TMTD 1.5 The present invention is concerned only with the treatment of chlorinated elastomers and is not concerned with fluoro-elastomers nor with highly fluorinated copolymers with chlorine compounds, since the curing mechanism of such elastomers and copolymers is quite different from that of chlorinated elastomers.

WHAT WE CLAIM IS: 1. A curable chlorinated elastomer composition comprising a chlorinated elastomer, at least one metal oxide as a curing agent and an accelerating agent comprising (A) at least one compound having the general formula: (HO)m-R1-Sx-R2-(OH)m (I) wherein R' and RZ each represent an aromatic ring, x is zero or an integer of I to 4, m and m' are each an integer of 2 to 4 and the OH groups may be attached at any position on each aromatic ring, and (B) at least one member selected from the group consisting of: (a) a compound having the general formula:

wherein R3, R4, R5 and R6 are each alkyl, aryl or aralkyl, and R3 and R4 or R5 and R6 may be linked to each other to form an alkylene group, and y is an integer of I to 4, (b) a compound having the general formula: :

wherein R7 and Ra are each an group aryl group or guanidino moiety -C(=NH)- NHR9 (R9 is hydrogen atom or aryl group), or a salt thereof.

(c) a compound having the general formula:

wherein R10, R", R12 and R'3 are each a hydrogen atom, or an alkyl, aryl or thiazolyl group, (d) a compound having the general formula:

wherein R'4 is a bivalent organic group and M' is a hydrogen atom, metal,

(z is an integer of 1 to 4 and R'4 is the same as defined above), or a monovalent organic group other than an amino group; or a salt thereof (e) a compound having either of the general formulae:

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. The present invention is concerned only with the treatment of chlorinated elastomers and is not concerned with fluoro-elastomers nor with highly fluorinated copolymers with chlorine compounds, since the curing mechanism of such elastomers and copolymers is quite different from that of chlorinated elastomers. WHAT WE CLAIM IS:

1. A curable chlorinated elastomer composition comprising a chlorinated elastomer, at least one metal oxide as a curing agent and an accelerating agent comprising (A) at least one compound having the general formula: (HO)m-R1-Sx-R2-(OH)m (I) wherein R' and RZ each represent an aromatic ring, x is zero or an integer of I to 4, m and m' are each an integer of 2 to 4 and the OH groups may be attached at any position on each aromatic ring, and (B) at least one member selected from the group consisting of: (a) a compound having the general formula:

wherein R3, R4, R5 and R6 are each alkyl, aryl or aralkyl, and R3 and R4 or R5 and R6 may be linked to each other to form an alkylene group, and y is an integer of I to 4, (b) a compound having the general formula::

wherein R7 and Ra are each an group aryl group or guanidino moiety -C(=NH)- NHR9 (R9 is hydrogen atom or aryl group), or a salt thereof.

(c) a compound having the general formula:

wherein R10, R", R12 and R'3 are each a hydrogen atom, or an alkyl, aryl or thiazolyl group, (d) a compound having the general formula:

wherein R'4 is a bivalent organic group and M' is a hydrogen atom, metal,

(z is an integer of 1 to 4 and R'4 is the same as defined above), or a monovalent organic group other than an amino group; or a salt thereof (e) a compound having either of the general formulae:

wherein R'5, R16, R17 and R18 are each an alkyl, aralkyl, aryl or cycloalkyl group.

and R'5 and R16 or R17 and R18 may be linked to each other to form an alkylene group, M2 is metal, and n is an integer of I to 5 corresponding to the valency of the metal, (f) a compound having the general formula:

wherein Rl9 and R20 are each an hydrogen atom, or an alkyl or cycloalkyl group, and the group

may be unsubstituted or substituted morpholino group, (g) a compound having either of the general formulae:

wherein R21 is an alkyl group, M3 is sodium or zinc and p is an integer of I to 2, (h) an aldehyde-amine condensation product, and (i) a compound having the general formula:: R22-S-S-R23 (XI) wherein R22 and R23 are each an alkyl, aryl, aralkyl, acyl or morpholino group, the amount of the ingredient (B) being 0.05 to 50 parts by weight per 1 part by weight of the ingredient (A).

2. The composition of Claim 1, wherein the chlorinated elastomer is a polychloroprene.

3. The composition of Claims 1 to 2, wherein the chlorinated elastomer is a polychloroprene unmodified with sulphur.

4. The composition of Claims 1 to 3, wherein the ingredient (A) is employed in a form of a reaction product which is obtained by reacting a polyhydroxy aromatic compound having 2 to 4 hydroxyl groups on its aromatic ring with sulphur monochloride or sulphur dichloride.

5. The composition of Claims 1 to 4, wherein the accelerating agent comprises I part by weight of the ingredient (A), 0.03 to 25 parts by weight of the compound (a) and 0.02 to 25 parts by weight of at least one member selected from the group consisting of the compounds (b) to (i).

6. The composition of Claims 1 to 5, wherein the accelerating agent is a mixture obtained by reacting 1.8 to 2.2 moles of a polyhydroxy aromatic compound having 2 to 4 hydroxyl groups on its aromatic ring with 1 mole of sulphur dichloride in an organic solvent, adding to the resulting reaction product the ingredient (B) in an amount of 0.05 to 50 parts by weight per I part by weight of the reaction product without isolating the reaction product from the reaction mixture, and taking out a mixture of the reaction product and the ingredient (B).

7. The composition of Claims 1 to 5, wherein the accelerating agent is a mixture obtained by reacting 1.8 to 3 moles of a polyhydroxy aromatic compound having 2 to 4 hydroxyl groups on its aromatic ring with 1 mole of sulphur monochloride in an organic solvent, adding to the resulting reaction product the ingredient (B) in an amount of 0.05 to 50 parts by weight per 1 part by weight of the reaction product without isolating the reaction product from the reaction mixture, and taking out a mixture of the reaction product and the ingredient (B).

8. A composition as claimed in any one of Claims 1 to 7, substantially as hereinbefore described.

9. A curable chlorinated elastomer composition, in accordance with claim 1 and substantially as described herein in any one of the examples.