JPS641501B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for crosslinking polychloroprene. Conventionally known methods for crosslinking polychloroprene include metal oxide vulcanization, sulfur vulcanization, and amine vulcanization. However, all of these conventional and widely practiced methods require a high temperature of 100° C. or higher for crosslinking, and the required crosslinked product cannot be obtained at room temperature and pressure. For example, in the metal oxide vulcanization method using magnesium oxide and zinc oxide, even if a generally known excellent vulcanization accelerator is used in combination, press vulcanization requires heating at 150℃ for 5 to 10 minutes. be. In the case of steam vulcanization, a continuous vulcanizer is used, and the extruded product is introduced into a vulcanization tube and heated with high-temperature, high-pressure steam to perform vulcanization. Alternatively, the material is extruded, covered with tape or lead, placed in a vulcanization pot, and vulcanized by directly introducing high-temperature, high-pressure steam. In any case, these conventional vulcanization methods require heating, which has the drawback of consuming a large amount of thermal energy such as electric heating, high temperature, and high pressure steam. Furthermore, for these conventional vulcanizations, heating press,
This method has the drawback of requiring special manufacturing equipment such as a continuous vulcanizer and a vulcanizing pot, which increases equipment costs. The present invention has been made to overcome these conventional drawbacks, and its particular purpose is to provide a method that can crosslink polychloroprene at room temperature and under normal pressure. A feature of the present invention that achieves this object is to react an aminoorganosilane compound or a mercaptoorganosilane compound with polychloroprene to produce a crosslinkable polychloroprene silane graftomer, so-called polychloroprene silane graftomer, and convert this silane graftomer into silanol. A method for crosslinking polychloroprene by contacting it with moisture in the presence of a condensation catalyst. The aminoorganosilane compound has the general formula RR′ _o SiX _3-o (wherein R is an organic group bonded to silicon via a silicon-to-carbon bond and has 20 or less carbon atoms; The group is composed of carbon, hydrogen, nitrogen and optionally oxygen and contains at least one amino group, R' is a monovalent hydrocarbon group having 1 to 9 carbon atoms, and X is 1 to 6 or an alkoxyalkoxy group having 14 carbon atoms or less, or an oxime group having 14 carbon atoms or less, and n is 0 or 1), and more specifically, as mentioned above, R is an organic group. and contains at least one amino group. The amino group includes primary, secondary and tertiary amino, and also includes amino. Therefore, examples of R groups are -(CH ₂ ) ₃ NHCH ₂ CH ₂ NH ₂ , -
(CH ₂ ) ₄ NHCH ₂ CH ₂ NH ₂ , -
(CH ₂ ) ₃ NHCH ₂ CH ₂ NHCH ₂ CH ₂ NH ₂ , -
CH ₂ CHCH ₃ CH ₂ NH (CH ₂ ) ₆ NH ₂ , -
(CH ₂ ) ₃ NH ₂ , - (CH ₂ ) ₄ NHCCH ₃ , -
(CH ₂ ) ₁₁ NH ₂ , ―NHSi(CH ₃ ) ₃ , ―
(CH ₂ ) ₃ NHCH ₂ CH ₂ NHCO・NH ₂ , and

Examples include [Formula]. Among these, R is of the formula -QNH ₂ or -
QNHCH ₂ CH ₂ NH ₂ (wherein, Q is -(CH ₂ ) ₃ -, -
(CH ₂ ) ₄ -- or --CH ₂ CHCH ₃ -- is preferred. R' is a monovalent hydrocarbon radical having 1 to 9 carbon atoms. Each X substituent may also be an alkoxy or alkoxyalkoxy group having 1 to 6 carbon atoms, such as methoxy, ethoxy, propoxy or methoxyethoxy, or an oxime group having up to 14 carbon atoms, such as -ON=C(CH ₃ )
(C ₂ H ₅ ), or -ON=C(CH ₃ )(C ₆ H ₅ ). Preferred aminoorganosilane compounds for use in the present invention are those in which X is an alkoxy group having 1 to 4 carbon atoms, e.g.
H ₂ NC ₃ H ₆ Si (OC ₂ H ₅ ) ₃ , CH ₃・NH・C ₃ H ₆ Si
(OC ₂ H ₅ ) ₃ , H ₂ NC ₂ H ₄ NHC ₃ H ₆ Si(OCH ₃ ) ₃ and the like are preferred. The mercaptoorganosilane compound then has the general formula R″R _o SiX _3-o (where R″ is an organic group bonded to silicon via a silicon-to-carbon bond and contains up to 20 carbon atoms; The R″ group consists of carbon, hydrogen, sulfur and optionally nitrogen, oxygen, and at least one
mercapto groups, R is a monovalent hydrocarbon group having 1 to 9 carbon atoms, and X is an alkoxy group having 1 to 6 carbon atoms, or an alkoxyalkoxy group having up to 14 carbon atoms. and n is 0 or 1). Next, a method for crosslinking polychloroprene using aminoorganosilane will be described in detail. First, polychloroprene and an aminoorganosilane compound are reacted to produce a crosslinkable polychloroprene silane graftomer. This reaction is thought to be based on the following reaction formula. However, the aminoorganosilane compound is represented by H ₂ NRR′ _o Si(OR″) _3-o . However, if this reaction is carried out above a certain temperature, crosslinking of polychloroprene will occur due to the amino groups. Although this temperature varies depending on the type of aminoorganosilane compound, the reaction occurs at a higher temperature than the reaction of formula (1) above. The crosslinking of polychloroprene in this case is thought to be based on the following reaction formula. When the reaction of formula (2) above occurs, so-called scorch (initial vulcanization) occurs during the molding process of polychloroprene, making it impossible to process it. That is, in order to obtain a polychloroprene silane graftomer according to formula (1), it is necessary to carry out the reaction at a temperature sufficiently lower than that at which formula (2) occurs. For example, when H ₂ NC ₃ H ₆ Si(OC ₂ H ₅ ) ₃ is used as the aminoorganosilane compound, it is necessary to carry out the heating at about 60°C to 80°C. A specific method for obtaining a silane graftomer of polychloroprene is to heat polychloroprene and an aminoorganosilane compound at 100°C or less, preferably from 40°C to 80°C.
The mixture may be sufficiently mixed at a temperature of 0.degree. C., and such mixing can be carried out using, for example, a two-roll kneader, a Banbury mixer, a kneader, an extruder, or the like. The amount of the aminoorganosilane compound used at this time is 0.1 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of polychloroprene. The silane-grafted polychloroprene thus obtained can be shaped by conventional extrusion or other methods and then crosslinked by contacting with water in the presence of a silanol condensation catalyst. In this case, crosslinking can occur even with moisture present in the atmosphere. Alternatively, moisture or a compound that releases moisture may be directly mixed with the polychloroprene silane graftomer and molded. Examples of compounds that release water include anhydrous inorganic salts that have a high water absorption rate and amount at room temperature, contain water in the polymer as water of crystallization, and release water of crystallization that is decomposed by heat during extrusion processing. Examples include sodium sulfate, sodium sulfite, magnesium sulfate, thallium sulfate, and strontium chloride. As the silanol condensation catalyst, a substance that promotes the formation of siloxane bonds in the presence of moisture can be used. The crosslinking of the polychloroprene graftomer with water in the presence of this silanol condensation catalyst is considered to be according to the following reaction formula. Various substances are already known that are effective as silanol condensation catalysts, including metal salts of carboxylic acids, titanium chelates, alkyl titanate esters, and organic acids. Examples include dibutyltin dilaurate, dibutyltin dioctoate, lead octoate, cobalt octoate, tetrabutyl titanate, P-toluenesulfonic acid, acetic acid, and the like.
Among these, preferred catalysts are organometallic compounds, and more specifically tin carboxylates, such as the above-mentioned dibutyltin dilaurate and dibutyltin diacetate. The blending of the silanol condensation catalyst may vary from 0.01 to 10 parts by weight based on 100 parts by weight of the polychloroprene graftomer. However, preferably
It is preferably 0.01 to 1 part by weight. This silanol condensation catalyst is preferably blended into the polychloroprene graftomer immediately before processing and molding. For example, a catalyst master patch containing a silanol condensation catalyst blended with untreated polychloroprene may be prepared in advance and mixed with the polychloroprene graftomer during processing and molding.
Alternatively, a processed polychloroprene graftomer may be brought into contact with an aqueous solution in which a silanol condensation catalyst is dispersed. The polychloroprene graftomer produced according to the present invention may optionally contain fillers, pigments,
Antiaging agents, processing aids, etc. can be added before or after making the graftomer. Although the above explanation was about an aminoorganosilane compound, polychloroprene can also be crosslinked by a similar reaction in the case of a mercaptoorganosilane compound. As described above, the crosslinked polychloroprene produced according to the present invention can be used without any problem in areas where conventionally crosslinked polychloroprene is used.
For example, it can be used for covering materials for electric wires and cables, sealing materials, pipes, etc. Examples of the present invention will be described below, but of course the present invention is not limited thereto. <Example> Formulation A (graftomer) Chloroprene 100 parts by weight Silane A1100, H ₂ NC ₃ H ₆ Si (OC ₂ H ₅ ) ₃ (manufactured by Nippon Unicar) 2 SPF carbon 45 Hard clay 60 Stearic acid 1 Process Oil 20 〃 The above formulation was roll kneaded at about 60°C to make a graftomer. Blend B (Catalyst Conc) Chloroprene 100 parts by weight Dibutyltin dilaurate 1 The above formulation was roll kneaded at about 60°C to prepare a catalyst conc. Graftomer of formulation A prepared in this way
A mixture of 100 parts by weight and 5 parts by weight of catalyst concretion of Formulation B was fed into an extruder and coated onto a 5.5 mm ² conductor. The extruded product was immersed in water at room temperature for one day, and the properties of the coating layer were measured, and the following results were obtained. 200% modulus 0.6Kg/mm ² Tensile strength 1.5Kg/mm ² Elongation 400% Heating deformation rate 25% Permanent deformation rate 5% <Comparative example> Formulation C Chloroprene 100 parts by weight Magnesia 5 Zinc white 5 Stearic acid 1 Anti-aging agent 1.5 〃 Vulcanization accelerator 22 1 〃 Vulcanization accelerator DM 0.5 〃 SRF carbon 45 〃 Hard clay 60 〃 Process oil 20 〃 For comparison with the present invention, the above formulation was prepared according to the conventional method. After roll kneading at 60°C, the mixture was fed to an extruder and coated onto a conductor. A cloth tape was wrapped on top of this coating layer, and the mixture was placed in a vulcanization pot at 150°C and heated for about 15 minutes to vulcanize it. When the properties of the coating layer thus vulcanized were measured, the following results were obtained. 200% Modulus 0.6Kg/ ^mm2 Tensile Strength 1.6Kg/ ^mm2 Elongation 403% Heating Deformation Rate 27% Permanent Deformation Rate 6% From the results of the above Examples and Comparative Examples, it is clear that cross-linked polychloroprene due to moisture in the present invention It can be seen that the properties are almost the same as those of the material crosslinked by heating using the conventional method. As described above, according to the present invention, polychloroprene can be crosslinked without heating and pressurizing. Therefore, a large amount of thermal energy such as electric heat, high temperature, and high pressure steam for heating is not required, and manufacturing costs can be reduced. In addition, special manufacturing equipment such as heated presses, continuous vulcanizers, and vulcanizing pots is no longer required, which reduces equipment costs and eliminates the need for heat management, which significantly simplifies equipment maintenance. be.

Claims (1)

[Claims] 1 polychloroprene and the general formula RR′ _o SiX _3-o (wherein R is an organic group bonded to silicon via a silicon-to-carbon bond and having 20 or less carbon atoms,
The R group is composed of carbon, hydrogen, nitrogen and optionally oxygen and contains at least one amino group, R' is a monovalent hydrocarbon group having 1 to 9 carbon atoms, and X is 1 an aminoorganosilane compound represented by an alkoxy group having 6 to 6 carbon atoms, an alkoxyalkoxy group, or an oxime group having up to 14 carbon atoms, where n is 0 or 1, or the general formula R'' _Ro
SiX _3-o (wherein R″ is an organic group bonded to silicon via a silicon-to-carbon bond and contains up to 20 carbon atoms, and the R″ group is a group that contains carbon, hydrogen, sulfur, and optionally consisting of nitrogen, oxygen and containing at least one mercapto group, R being a monovalent hydrocarbon radical having 1 to 9 carbon atoms, and X having 1 to 6 carbon atoms. or an alkoxyalkoxy group or an oxime group having up to 14 carbon atoms, and n is 0 or 1) to form a crosslinkable polychloroprene. A method for crosslinking polychloroprene, which comprises bringing it into contact with moisture in the presence of a silanol condensation catalyst.