CN109608568B - Chloroprene rubber latex chain breaking process - Google Patents
Chloroprene rubber latex chain breaking process Download PDFInfo
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- CN109608568B CN109608568B CN201811459928.0A CN201811459928A CN109608568B CN 109608568 B CN109608568 B CN 109608568B CN 201811459928 A CN201811459928 A CN 201811459928A CN 109608568 B CN109608568 B CN 109608568B
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F136/00—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
- C08F136/02—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
- C08F136/04—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
- C08F136/14—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated containing elements other than carbon and hydrogen
- C08F136/16—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated containing elements other than carbon and hydrogen containing halogen
- C08F136/18—Homopolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated containing elements other than carbon and hydrogen containing halogen containing chlorine
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Abstract
The invention relates to the technical field of chloroprene rubber preparation, and particularly discloses a chloroprene rubber latex chain breaking process. The Mooney viscosity stability of the sulfur-regulated neoprene latex is good after chain breakage is qualified by adopting the technical scheme in the patent, and the produced sulfur-regulated neoprene rubber product has good quality and good storage stability.
Description
Technical Field
The invention relates to the technical field of chloroprene rubber preparation, in particular to a chloroprene rubber latex chain breaking process.
Background
Chloroprene rubber is divided into a sulfur regulation type and a non-sulfur regulation type according to different regulation modes, and the prior sulfur regulation type chloroprene rubber has two processes for meeting the Mooney viscosity required by a product in the production process: a method for preparing qualified neoprene latex is disclosed in both Chinese patent publication No. CN107674138A and Chinese patent publication No. CN102040677B, which features that no independent chain-breaking process is used, and the regulator or chain-breaking agent is added to oil phase and water phase for reaction during polymerization to obtain qualified neoprene latex. The chloroprene rubber produced by the process has the problems of good Mooney viscosity stability, insufficient product strength and poor processability. Another process is a conventional process, in which a compound such as dithiotetraethylthiuram (TETD) is added under an alkaline condition to cleave S-S bonds, thereby obtaining a polymer having a Mooney viscosity industrially required. Although the traditional process has good product quality, the speed is low in the early stage of chain breakage, the Mooney viscosity is reduced quickly in the later stage, the production control is difficult, and the Mooney viscosity stability of the product is poor.
Disclosure of Invention
The invention provides a chloroprene rubber latex chain scission process, which aims to solve the problems that finished products produced by two conventional chain scission processes have good Mooney viscosity stability but insufficient strength; or the product has enough strength, but the speed in the early stage of chain breakage is slow, the Mooney viscosity in the later stage is reduced quickly, the production control is difficult, and the Mooney viscosity stability of the product is poor.
In order to achieve the purpose, the basic scheme of the invention is as follows:
a process for breaking the chain of chloroprene rubber latex includes such steps as adding chain-breaking agent, which is the combination of carbamate compound and thiuram compound, and alkali solution to the latex when the polymerization reaction of sulfur-regulating chloroprene rubber is finished.
The technical principle and the effect of the basic scheme are as follows:
1. the basic scheme has the effects that the chain breaking agent is added when the polymerization reaction of the sulfur-regulating chloroprene rubber is terminated: because the polymerization reaction of the chloroprene rubber is terminated, the latex is basically macromolecular polymers, the macromolecular polymers are subjected to chain scission under the promotion of a chain scission agent to form polysulfide bonds, and the polysulfide bonds and the chloroprene form relatively complete and uniform polymer molecules, so that the product produced by the basic scheme has high strength and good processing performance. Compared with the prior art, the chain scission agent is added into the water phase, the chain scission agent is added at the moment, the macromolecular polymer is promoted to be subjected to chain scission to generate polysulfide bonds once being formed, the chain scission speed of the process is high, but the process is not clear and controllable, and the finally formed polymer usually contains a large amount of low molecules, so that the product produced by the process has insufficient strength and poor processability.
2. In the basic scheme, a chain breaking agent and an alkaline solution are simultaneously added into latex when the polymerization reaction of the sulfur-regulated chloroprene rubber is terminated, thiuram in the chain breaking agent reacts with the alkaline solution, and because the reaction speed of the thiuram and the alkaline solution is low, a carbamate compound is added in the early stage, so that the chain breaking can be rapidly carried out, and when the carbamate compound is reacted, the thiuram and the alkaline solution can continuously react to generate carbamate in the chain breaking process, so that the chain breaking reaction can be continuously carried out, no back molding is generated, the Mooney viscosity of the sulfur-regulated chloroprene latex can be kept stable after the chain breaking is qualified, and the product quality and the product storage stability are simultaneously ensured.
Further, the alkaline solution is NaOH aqueous solution, the mass concentration of the NaOH aqueous solution is 3% -6%, and the adding amount of the NaOH aqueous solution is controlled to keep the pH value of the latex within the range of 8-12.
Has the advantages that: by adding NaOH aqueous solution when chloroprene rubber polymerization reaction is terminated and adjusting the pH value in chain breaking within the range of 8-12, the chain breaking reaction can be normally carried out at the required speed, the Mooney viscosity of latex is kept relatively stable after chain breaking is qualified, and the Mooney viscosity difference of the product is within the required range.
Further, the latex accounts for 100 parts by weight, the carbamate compound accounts for X parts by weight, and the value of X is greater than 0 and less than or equal to 1.
Has the advantages that: the addition of the carbamate ensures that the chain breaking speed can be higher in the early stage, the chain breaking period is shortened, and in addition, in order to avoid the influence of excessive use amount of the carbamate on the rubber quality, through a plurality of experiments and production verification, the added weight part of the carbamate in 100 parts by weight of the latex is not more than 1.
Furthermore, the weight part of the thiuram compound is more than 0 and less than or equal to 2.
Has the advantages that: the autumn orchid chain scission agent can react with alkali to generate carbamate, so that the chain scission reaction can be continuously carried out without generating the phenomenon of plastic recovery. Meanwhile, a proper amount of thiuram guarantees the quality and the storage stability of the chloroprene rubber product, and the inventor verifies through experiments that the weight part of thiuram compounds is more than 0 and less than or equal to 2, and the product obtained by chain scission has good quality.
Further, the temperature of the latex is maintained in the range of 10 ℃ to 60 ℃ during the chain scission reaction.
Has the advantages that: the temperature is adjusted to ensure that the latex after the chloroprene rubber polymerization reaction is terminated normally carries out chain scission reaction, and the phenomenon of plastic recovery or too low later Mooney viscosity caused by too high reaction speed is avoided.
Detailed Description
The following is further detailed by way of specific embodiments:
a chloroprene rubber latex chain breaking process, adding chain breaking agent and alkaline solution into latex when the polymerization reaction of sulfur-regulating chloroprene rubber is terminated, wherein the chain breaking agent is the combination of carbamate compound and thiuram compound; wherein the chain scission agent may be formulated in the terminating agent or otherwise formulated separately and added at the termination of the polymerization reaction, in this example a separate formulation is employed and added at the termination of the polymerization reaction.
The alkaline solution is NaOH aqueous solution, NaOH aqueous solution with the mass concentration of 3-6% is added into 100g of latex to ensure that the pH value of the latex is in the range of 8-12, in addition, the mass of carbamate added into the latex is more than 0 and less than or equal to 1g, the mass of added thiuram is more than 0 and less than or equal to 2g, the temperature of the latex can fluctuate within a specific value during chain scission, and the value is kept within the temperature range of 10-60 ℃.
The carbamate compound can be one of dithiodimethyl sodium carbamate, dithiodiethyl sodium carbamate or dithiodibutyl sodium carbamate, and the thiuram compound can be one of dithiotetramethyl thiuram, dithio tetraethyl thiuram, dithio tetrabutyl thiuram or dithio tetrapentyl thiuram.
Table 1 below shows the mass of carbamate and thiuram added, and the pH range for examples 1-6:
TABLE 1
Comparative example 1: chinese patent publication No. CN107674138A discloses a method for preparing sulfur-modified chloroprene rubber without chain scission at the later stage, that is, after the polymerization of chloroprene rubber latex, there is no chain scission process, but a regulator is added into the aqueous phase, wherein the regulator is sodium dithiodibutylaminoate, the embodiment disclosed in paragraph [ 0029 ] of the specification is selected as the present comparative example 1:
12.5g of sodium dithiodibutylaminoate was added to the aqueous phase to prepare a sulfur-modified chloroprene rubber. The emulsifier added into the water phase is rosin. Through detection, the initial Mooney viscosity average value of the sulfur-modified chloroprene rubber is 47, and the tensile strength is 26.0; wherein the Mooney viscosity is 43 and 41 respectively after standing for 24h and 36 h.
Comparative example 2: the conventional process is to add a compound such as dithiotetraethylthiuram (TETD) under an alkaline condition to break S-S bonds, thereby obtaining a polymer with a Mooney viscosity required in industry. After chain scission is qualified, the Mooney viscosity is 52, and the strength is 29.3; the Mooney viscosity after 24h of standing was 20.
The results obtained from the experiments of the above examples 1-6 are:
wherein, the Mooney viscosity is tested by sampling every 0.5-2 hours until the chain breaking is qualified (the Mooney viscosity is less than or equal to 65 is qualified). And standing the qualified broken-chain latex for 24 hours, and then testing the Mooney viscosity to obtain the stability of the Mooney viscosity of the sulfur-regulated chloroprene latex after qualified broken chain.
In addition, the quality of the dry rubber product is examined by detecting the dry rubber product according to the sulfur-modified chloroprene rubber detection standard and method, and the storage stability of the rubber is examined by aging the dry rubber product in a hot air aging box at 70 ℃ for three days through a hot air aging experiment.
The results of the experiment are shown in table 2 below:
TABLE 2
And (4) conclusion: by combining the experimental data of the examples 1-6 and the experimental data of the comparative examples 1-2, the Mooney viscosity stability of the sulfur-adjusted chloroprene rubber latex is good after chain scission is qualified by adopting the technical scheme in the patent, and the produced sulfur-adjusted chloroprene rubber product has good quality and good storage stability. In summary, according to the present invention, a chain scission agent and an alkaline solution, which is a combination of carbamate and thiuram, are added to the latex at the end of the sulfur-regulated neoprene polymerization reaction. Within the chain breaking temperature range, the chain breaking of the chloroprene rubber latex is adjusted by adjusting the using amounts of the chain breaking agent and the alkali solution, so that the problems of high stability of Mooney viscosity, insufficient quality or high quality of products in the prior two processes, but low speed in the early stage of chain breaking, high reduction of later Mooney viscosity, difficulty in production control and low stability of Mooney viscosity of products are solved. After chain scission is qualified, the Mooney viscosity of the neoprene latex can be stably adjusted by sulfur. The sulfur-regulated chloroprene rubber product has good quality and good storage stability.
The foregoing is merely an example of the present invention and common general knowledge of known specific structures and features of the embodiments is not described herein in any greater detail. It should be noted that, for those skilled in the art, without departing from the structure of the present invention, several changes and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.
Claims (5)
1. A chloroprene rubber latex chain breaking process is characterized in that: and adding a chain breaking agent and an alkali solution into the latex when the polymerization reaction of the sulfur-regulated chloroprene rubber is terminated to perform a chain breaking reaction, wherein the chain breaking agent is a combination of a carbamate compound and a thiuram compound.
2. The neoprene latex delinking process of claim 1, wherein: the alkali solution is NaOH aqueous solution, the mass concentration of the NaOH aqueous solution is 3-6%, and the adding amount of the NaOH aqueous solution is controlled to keep the pH value of the latex within the range of 8-12.
3. The neoprene latex delinking process of claim 1, wherein: the latex is 100 parts by weight, the carbamate compound is X parts by weight, and the value of X is more than 0 and less than or equal to 1.
4. The neoprene latex delinking process of claim 3, wherein: the weight part of the thiuram compound is more than 0 and less than or equal to 2.
5. The process of claim 1-4, wherein the neoprene latex is subjected to chain scission: the temperature of the latex is kept in the range of 10 ℃ to 60 ℃ during the chain scission reaction.
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Citations (6)
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|---|---|---|---|---|
| JP2001131234A (en) * | 1999-11-01 | 2001-05-15 | Tosoh Corp | High-elasticity sulfur-modified chloroprene rubber |
| CN1389473A (en) * | 2002-07-16 | 2003-01-08 | 华南理工大学 | Prepn. of powdered neoprene and granulated neoprene |
| CN101284894A (en) * | 2008-06-03 | 2008-10-15 | 重庆长寿化工有限责任公司 | Sulfur-modified neoprene, method for preparing same and applications |
| CN102516618A (en) * | 2011-11-24 | 2012-06-27 | 山西合成橡胶集团有限责任公司 | Compounded emulsion stabilizer in sulfur-modified neoprene rubber |
| CN103554321A (en) * | 2013-09-29 | 2014-02-05 | 安徽同丰橡塑工业有限公司 | Production technology for chloroprene rubber |
| CN104403039A (en) * | 2014-11-07 | 2015-03-11 | 山纳合成橡胶有限责任公司 | Preparation method of sulfur-modified chloroprene rubber with high latex Mooney viscosity stability |
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- 2018-11-30 CN CN201811459928.0A patent/CN109608568B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001131234A (en) * | 1999-11-01 | 2001-05-15 | Tosoh Corp | High-elasticity sulfur-modified chloroprene rubber |
| CN1389473A (en) * | 2002-07-16 | 2003-01-08 | 华南理工大学 | Prepn. of powdered neoprene and granulated neoprene |
| CN101284894A (en) * | 2008-06-03 | 2008-10-15 | 重庆长寿化工有限责任公司 | Sulfur-modified neoprene, method for preparing same and applications |
| CN102516618A (en) * | 2011-11-24 | 2012-06-27 | 山西合成橡胶集团有限责任公司 | Compounded emulsion stabilizer in sulfur-modified neoprene rubber |
| CN103554321A (en) * | 2013-09-29 | 2014-02-05 | 安徽同丰橡塑工业有限公司 | Production technology for chloroprene rubber |
| CN104403039A (en) * | 2014-11-07 | 2015-03-11 | 山纳合成橡胶有限责任公司 | Preparation method of sulfur-modified chloroprene rubber with high latex Mooney viscosity stability |
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