JPH0410888B2 - - Google Patents

Description

[Detailed description of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to chloroprene polymers. More specifically, the present invention relates to chloroprene copolymers with significantly improved oil resistance, weather resistance, heat resistance, and cold resistance. Chloroprene, i.e. 2-chloro-1,3-
Chloroprene rubber, which is made of a homopolymer or copolymer of butadiene, has been used in a variety of fields as an elastomer with the most balanced physical properties. However, having well-balanced physical properties means that chloroprene rubber has average characteristics in each physical property, and does not mean that each physical property is particularly excellent. Therefore, chloroprene rubber is inferior to butadiene-acrylonitrile copolymer rubber in oil resistance, inferior to ethylene-propylene copolymer rubber in weather resistance, inferior to chlorosulfonated polyethylene in heat resistance, and inferior to natural rubber and polybutadiene rubber in cold resistance. is inferior to For this reason, in certain fields, chloroprene rubber cannot be used or is being replaced by other rubbers. SUMMARY OF THE INVENTION The present invention aims to provide a solution to the above-mentioned problems, and attempts to achieve this object by means of a chloroprene polymer containing a specific comonomer component. Therefore, the chloroprene polymer according to the invention is
The following monomer units A, B and/or C, and D are randomly arranged in the following ratio, and the number average degree of polymerization of the main chain portion is 20 to 1.2 × 10 ⁴
It is something that is.

[Table] However, when both monomer units B and C are included in the chloroprene copolymer, the sum of both does not exceed 1/10 of the monomer unit A1 unit. Here, the symbols have the following meanings. R ¹ and R ⁴ : Each independently, a hydrogen atom or a methyl group, R ² : A straight chain or branched alkylene group having an average carbon number of 2.5 to 6 (the plurality of R ² may not be the same), n: a number from 4 to 20, R ³ : hydrogen atom, alkyl group having 1 to 3 carbon atoms, or X: 1,2- of 2-chloro-1,3-butadiene
Monomer unit by addition, 2-chloro-1,3-
Monomer unit by 3,4-addition of butadiene,
Monomer units from 2,3-dichloro-1,3-butadiene, monomer units from 1-chloro-1,3-butadiene, monomer units from styrene, monomer units from acrylonitrile, Monomer units from methacrylic acid, monomer units from acrylic acid, monomer units from methacrylic acid alkyl ester and -(S _n )- (where m
is an integer of at least 1). Effects As described above, the present invention has succeeded in solving the above-mentioned problems observed in conventional chloroprene rubber by bonding a polyether chain to a chloroprene polymer chain. Polyether chains are molecular chains with excellent oil resistance, cold resistance, weather resistance, etc., but they have poor compatibility with chloroprene rubber, so for example, chloroprene rubber and polypropylene glycol are mixed in a rubber kneading machine. Even if the mixture is kneaded and vulcanized, not only is no improvement in physical properties observed, but the strength of the vulcanized product is extremely reduced, and furthermore, the blended polypropylene glycol oozes out onto the surface of the vulcanized product. It will be done. The present invention is based on the fact that even if polyether molecular chains have poor compatibility with chloroprene rubber, those having an acryloyl or methacryloyl group at one or both ends can be copolymerized with chloroprene, and that the produced chloroprene copolymer is This was achieved by unexpectedly discovering that the oil resistance, weather resistance, heat resistance, and cold resistance are significantly improved compared to chloroprene rubber. Detailed Description of the Invention Chloroprene Copolymer Definition The chloroprene copolymer according to the present invention is as defined above. The copolymer of the present invention has monomer units A to D (details will be described later).
These units are randomly arranged in a predetermined amount to form a molecular chain. This copolymer has a number average degree of polymerization of the main chain portion of 20.
~1.2× ¹⁰⁴ . This number average degree of polymerization is 20
If the number average degree of polymerization is less than 1.2 × 10 ⁴ , the copolymer cannot be vulcanized using the vulcanization conditions and formulations commonly used for chloroprene rubber. On the other hand, copolymers with a number average degree of polymerization of more than 1.2 difficult to do. In the present invention, the "number average degree of polymerization of the main chain portion" means the number average molecular weight of the copolymer of the present invention when all the ester groups of monomer units B and C in the copolymer are hydrolyzed. do. Therefore, "main chain" means a polymer chain that does not include polyether chains. In the present invention, the number average degree of polymerization is measured by the following method. In other words, the end groups and main chain monomer units are quantified by nuclear magnetic resonance absorption of hydrogen atoms using a nuclear magnetic resonance absorption device "FX-90Q" manufactured by JEOL Ltd., and the ratio is calculated by number average. Let it be the degree of polymerization. Incidentally, the terminal groups and the main chain monomer units can also be quantified using a Fourier transform infrared spectrophotometer or the like. Monomer units B to C are units that impart polyether chains to the copolymer of the present invention. The content of monomer unit B is 1 unit per 10 to 700 units of monomer unit A (that is, units resulting from 1,4-addition of 2-chloro-1,3-butadiene). If the number of this unit is more than 1 per 10 units A, the strength of the vulcanizate of the copolymer will be extremely low;
If there is less than one unit per unit, the copolymer will not be able to enjoy the properties derived from unit B. The content of monomer unit C is 1 unit per 10 to 2000 units of monomer A, and the reason for this limitation is the same as in the case of monomer B described above. The reason why the lower limit of the content of unit C may be lower than that of monomer unit B is due to the difference in the bonding mode between the two with the main chain. That is, in unit B, the polyether chain is bonded to the chloroprene main chain as a side chain, while in unit C, it is bonded as a "bridge" between the main chains and exists as a component of the polymer chain, so it is not a polyether chain. This is because the effect of introducing the chain is easily expressed. When the copolymer of the present invention contains monomers B and C at the same time, it is necessary that the content phase of both of them does not exceed 1 for every 10 units A. This is because if this condition is not met, the strength of the vulcanizate of the copolymer will be significantly reduced. Furthermore, when the copolymer of the present invention contains monomer unit C, the copolymer may contain substantially toluene-insoluble components since unit C can serve as a crosslinking unit between main chains. Since the content of monomer unit C is limited as described above, the toluene-insoluble content in the copolymer is 95% or less, and the degree of swelling of the toluene-insoluble content is 50 or less. Here, the toluene insoluble content and its degree of swelling were determined by the method shown below. That is, copolymer ag was immersed in 100 x ag of toluene, left at room temperature for 2 days, passed through 200 mesh of gold wire, and the weight (bg) of the copolymer swollen with toluene on the gold wire was measured. and then run it for 2 days at 15 Torr
Dry it in a vacuum and measure the weight (cg).
From these, the following calculations are performed. Toluene insoluble content (%) = c/a x 100 Swelling degree of toluene insoluble content = (a/b-1) (ρ ₁ /ρ ₂ ) Here, ρ ₁ is the density of the chloroprene copolymer (g/cc ), ρ ₂ indicates the density of toluene (g/cc). Monomer unit D corresponds to a third comonomer that may be included in the copolymer of the present invention as required.
The amount of monomer unit D is 0 to 1/ of monomer unit A.
It is 10 units. If the amount of monomer unit D exceeds this value, the copolymer will have problems such as poor cold resistance and reduced strength of the vulcanizate. Monomer unit A Monomer unit A is produced by 1,4-addition of 2-chloro-1,3-butadiene, and is a main component of the copolymer of the present invention. . These monomer units include trans-type and cis-type, and the copolymer of the present invention may be either of these types. By the way, conventional polychloroprene has a trans-1,4 structure with 71 to 94
%, and the cis-1,4 structure accounts for 13-5% (revised new edition "Synthetic Rubber Handbook").
Page 270 (Published by Asakura Shoten on August 10, 1964) (For monomer units formed by 1,2-addition and 3,4-addition of chloroprene, please refer to the section on monomer unit D) . Monomer units B and C These monomer units are:

It is formed from mono- or bis(meth)acrylates of the formula (R ¹ to R ³ and n are defined as above). (The term "meth)acrylate" refers to both acrylates and methacrylates. ). ^R2 in the polyether chain of this (meth)acrylate is a straight or branched alkylene group having 2.5 to 6 carbon atoms. If R ² is less than 2.5 on average, the copolymer will not have sufficient cold resistance;
If R ² has more than 6 carbon atoms, the copolymer will not have sufficient oil resistance and cold resistance. The repeating number n of polyether units is 4-20. If it is less than 4, the modification effect of the present invention is insufficient, while if it exceeds 20, the strength of the vulcanizate is too low. Note that n is originally an integer, but since this (meth)acrylate is usually produced by a method that involves the addition of alkylene oxide, and the number of alkylene oxides added is expressed as an average value, ( In standard meth)acrylates, n will often be expressed as a decimal number or as a number with a certain range. The monomer unit C of this (meth)acrylate is
Needless to say, it can exist only when R ³ is a (meth)acryloyl group, but even when R ³ is a (meth)acryloyl group, the (meth)acryloyl group is It can exist as monomer unit B while retaining the saturated bond (for example, when the copolymer of the present invention is produced by emulsion polymerization of related monomers and the polymerization rate is kept low). Some specific examples of such (meth)acrylates include polypropylene glycol dimethacrylate (n=9. Trade name: NK Ester).
9PG” (manufactured by Shin Nakamura Chemical Industry Co., Ltd.), polypropylene glycol monomethacrylate (n = 5 to 6,
^R3 =H. Product name "Blemmer PP-1000" (manufactured by NOF Corporation), polytetramethylene glycol diacrylate (n = 15 to 16), poly(ethylene) (tetramethylene) glycol monomethacrylate (n = 5 to 7. R ₃ = H. The average number of carbon atoms in the alkylene group is approximately 3. Product name: “Blemmer-55PET-800”
(manufactured by Nippon Oil & Fats Co., Ltd.), etc. Monomer Unit D Monomer unit D can be broadly classified into three groups. The first group is units formed by 1,2-addition and 3,4-addition of 2-chloro-1,3-butadiene, which should constitute the monomer unit A. In conventional polychloroprene, the endowment of units from 1,2-addition and 3,4-addition is 0.9 each.
~2.4% and 0.3~2.4% (ibid., p. 270). In the copolymer of the present invention, 1,2- and 3,
It is possible that 4-addition polymerization will inevitably occur and these monomer units will be included. The second group of monomer units D, optionally and purposefully introduced, are from specific ethylenically unsaturated monomers. wherein the monomer is selected from the group consisting of 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, acrylonitrile, methacrylic acid, acrylic acid and methacrylic acid alkyl ester. It is something that was given. 2,3-dichloro-
1,3-butadiene and 1-chloro-1,3-
Butadiene is 1,4-, 1,2- and 3,4
- May be of any additional structure. The alkyl group of the methacrylic acid alkyl ester preferably has about 1 to 8 carbon atoms. A plurality of types of these monomer units may be included. The third group of monomer units D are thio or polythio groups of the formula -(S _n )-, where m is an integer of at least 1. The upper limit of m is about 8. Thio or polythio groups do not fall into the category of monomer units when they are to be understood as ethylenically unsaturated monomers, but sulfur is added during the polymerization of chloroprene. In defining the chloroprene copolymer of the present invention, sulfur is incorporated into the polymer chain of polychloroprene to form a thio or polythio group and exhibit the same behavior as a copolymer. -S _n -) group shall be treated as a monomeric unit. Polychloroprene having (-S _n -) groups is commercially available. Production of Copolymer The copolymer of the present invention can be produced by any suitable method. One preferred method of preparation consists of polymerizing the relevant monomers all at once or in stages. Typical of such methods are the methods customary for the polymerization of chloroprene, in particular the atmospheric emulsion polymerization method. Chloroprene is added to the emulsion polymerization system all at once or in stages, and related monomers are added all at once or in stages, and the mixture is heated at 5 to 60°C.
The polymerization may be carried out at a certain level. The polymerization rate or conversion rate of chloroprene is preferably 60% or more. When chloroprene is added in portions, a copolymer that provides a vulcanizate with high strength is easily obtained. For details of polymerization methods including methods other than emulsion polymerization, please refer to pages 266 to 269 of the above-mentioned book. Another specific example of the method for producing the copolymer of the present invention is a chloroprene polymer consisting of monomer units A and optionally D (or further containing some monomer units B to C as required). thing)
and (meth)acrylate giving monomer units B to C are kneaded. During kneading, the chloroprene polymer chain is cut to generate radicals, which are copolymerized with (meth)acrylate to form the copolymer of the present invention. Therefore, it is also possible to add a peptizer (eg, tetramethylthiuram disulfide, etc.) to promote the scission of polymer chains during kneading. The kneading can be carried out using a kneader, a roll, or other equipment commonly used for melting rubber. Applications The chloroprene copolymer of the present invention can be compounded, vulcanized, molded, and otherwise processed according to methods commonly used for processing chloroprene rubber, and by taking advantage of its improved physical properties, these It can be used in fields where conventional chloroprene rubber could not be used due to insufficient physical properties. Experimental Examples "Parts" and "%" in the following illustrative examples of the present invention and comparative examples are based on weight unless otherwise specified. Moreover, the polyether (meth)acrylate used in each example is shown by a symbol, and the contents are as follows. a: Polypropylene glycol monomethacrylate

[Formula] (n=5-6) "Blenmar PP-1000" manufactured by NOF b: Polypropylene glycol dimethacrylate "NK Ester 9PG" manufactured by Shin Nakamura Chemical Co., Ltd. c: Polytetramethylene glycol diacrylate CH ₂ = CH-COO (-C ₄ H ₈ -O) - _o OC-CH =
CH ₂ (n=15-16) Kyoeisha Yushi Kagaku Kogyo Co., Ltd. Prototype d: Polyethylene glycol diacrylate CH ₂ =CH−COO(−C ₂ H ₄ −O)− ₁₄ OC−CH=
CH ₂ "NK Ester A-600" manufactured by Shin-Nakamura Chemical Co., Ltd. e: Tripropylene glycol diacrylate CH ₂ = CH-COO (-C ₃ H ₆ -O)- ₃ OC-CH =
CH ₂ "NK Ester APG-200" manufactured by Shin Nakamura Kagaku Co., Ltd. Examples 1 to 5 Polymerization was carried out in a stainless steel polymerization can with an internal volume of 30 liters. In other words, in a nitrogen stream, water
200 parts of rosin acid, 5 parts of disproportionated rosin acid as an emulsifier, 2 parts of a formaldehyde-sodium naphthalene sulfonate condensate as a dispersant, and 0.8 parts of caustic soda as a polymerization aid, and while stirring, the mixture shown in Table 1 was added. The monomer mixture described was added together with n-dodecyl mercaptan. Polymerization was carried out using formamidine sulfinic acid as a radical polymerization initiator under the conditions listed in Table 1, and after the conversion of chloroprene monomer reached 70%, para-tertiary butylcatechol and thiodiphenylamine were added to carry out the polymerization. It stopped. Unreacted chloroprene monomer was removed by steam stripping, and dry polymer was isolated from the resulting latex by a conventional freeze-coagulation method. The structure of the produced polymer is shown in Table 3, and the properties are shown in Table 4. Comparative Examples 1-4 Dry polymers were isolated using the same formulations as shown in Examples 1-5 using the monomer compositions and polymerization conditions listed in Table 1. The structure of the polymer is listed in Table 3, and the properties are listed in Table 4. Examples 6 to 7 100 parts of commercially available polychloroprene (“PM-40” manufactured by Denki Kagaku Kogyo Co., Ltd.) and polyether (meth)acrylate with the composition shown in Table 2 were mixed into an 8-inch rubber kneading tube. Roll for 60 minutes (roll spacing 1mm,
The mixture was kneaded (roll temperature: 60°C) to obtain a pale yellow polymer. The structure of the polymer is listed in Table 2, and the properties are listed in Table 4. Comparative Example 5 A light yellow polymer was obtained by kneading the composition shown in Table 2 under the same conditions as those shown in Examples 6 and 7. The structure of the polymer is listed in Table 2, and the properties are listed in Table 4. In addition, in Examples 1 to 5 and Comparative Examples 1 to 4,
Vulcanization was performed using the following formulation and physical properties were measured. (a) Blended polymer 100 parts Phenyl α-naphthylamino 1 Magnesia 4 Zinc white 5 2-mercaptoimidazoline 0.35 (b) Vulcanization Press vulcanization at 141°C for 25 minutes In Examples 6 to 7 and Comparative Example 5, the following formulation was used. Vulcanization was performed and physical properties were measured. (a) Blended polymer 100 parts Stearic acid 0.5 Magnesia 4 Zinc white 5 (B) Vulcanization Press vulcanization at 150°C for 15 minutes In addition, the polymer structures shown in Tables 2 and 3 are manufactured by JEOL Co., Ltd. Nuclear Magnetic Using the resonance device “FX-90Q”,
Quantification of terminal groups of polychloroprene main chain, quantification of reacted (cleaved) (meth)acryloyl groups and unreacted (meth)acryloyl groups, and 2,3-dichloro-butadiene units by nuclear magnetic resonance spectroscopy of hydrogen atoms. It was determined by quantitative determination of

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Claims (1)

[Claims] 1. The following monomer units A, B and/or
C and D are randomly arranged in the following ratio, and the number average degree of polymerization of the main chain portion is 20 to 20.
1.2×10 ⁴ chloroprene copolymer. [Table] However, when both monomer units B and C are included in the chloroprene copolymer, the sum of both does not exceed 1/10 unit per monomer unit A1 unit. Here, the symbols have the following meanings. R ¹ and R ⁴ : Each independently, a hydrogen atom or a methyl group, R ² : A straight chain or branched alkylene group having an average carbon number of 2.5 to 6 (the plurality of R ² may not be the same), n: a number from 4 to 20, R ³ : hydrogen atom, alkyl group having 1 to 3 carbon atoms, or X: 1,2- of 2-chloro-1,3-butadiene
Monomer unit by addition, 2-chloro-1,3-
Monomer unit by 3,4-addition of butadiene,
Monomer units from 2,3-dichloro-1,3-butadiene, monomer units from 1-chloro-1,3-butadiene, monomer units from styrene, monomer units from acrylonitrile, From the group consisting of monomeric units from methacrylic acid, monomeric units from acrylic acid, monomeric units from methacrylic acid alkyl esters, and -(S _n )- (where m is an integer of at least 1) At least one monomeric unit selected. 2. The chloroprene copolymer according to claim 1, which contains monomer unit C, and has a toluene-insoluble content of 95% or less and a swelling degree of the toluene-insoluble content of 50 or less. .