JPS6259132B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a self-curing liquid chloroprene polymer having carboxyl groups and epoxy groups in the molecule. Chloroprene-based polymers having carboxyl groups have been known for a long time, but
There was no known method for producing a chloroprene polymer having two types of functional groups, a carboxyl group and an epoxy group. Carboxyl groups and epoxy groups easily react in the presence of a basic catalyst such as a tertiary amine to form a hydroxy ester, and the epoxide itself is easily ring-opened by both electrophiles and nucleophiles. It is well known that these two types of functional groups are present in the same molecule, and it has been considered difficult to stably produce a polymer having these two types of functional groups in the same molecule and to produce a product with excellent storage stability. However, since it is assumed that polymers having these two types of functional groups exhibit self-curing properties due to their mutual reactions, it has been desired to establish a method for producing them. In view of these points, the inventor has made extensive studies, and
The present invention was achieved by discovering a method for producing a novel liquid chloroprene polymer having a carboxyl group and an epoxy group in the same molecule. The object of the present invention is to have excellent storage stability, and the carboxyl group and epoxy group introduced into the same molecule easily react with each other in the presence of a basic catalyst such as a tertiary amine or an alkali metal hydroxide. An object of the present invention is to provide a method for producing a curable liquid chloroprene polymer. The present invention uses chloroprene monomer alone or together with a monomer copolymerizable therewith. (In the formula, R is hydrogen or an alkyl group having 1 to 2 carbon atoms). Aromatic hydrocarbons and aliphatic halogenated compounds having a boiling point of 150°C or less at normal pressure in the presence of mercaptocarboxylic acid in an amount equivalent to that of 20 to 200 parts by weight per 100 parts by weight of total monomers. This is a method for producing a self-curing liquid chloroprene polymer, which is characterized by copolymerizing in an organic solvent selected from hydrocarbons and cyclic ethers. That is, the present invention has a main chain consisting of repeating units of chloroprene, at least 1 to 2.5 epoxy groups derived from unsaturated glycidyl ester monomers in the molecule, and at least one mercaptocarboxylic acid group at the end of the molecule. It has a carboxyl group derived from
Provided is a method for producing a self-curing liquid chloroprene polymer having a number average molecular weight of 3,000 to 20,000. That is, the present invention has a main chain consisting of a repeating unit of chloroprene, at least 1 to 2.5 epoxy groups derived from an unsaturated glycidyl ester monomer in the molecule, and at least one mercaptocarboxylic acid group at the end of the molecule. It has a carboxyl group derived from
A self-curing liquid chloroprene polymer having a molecular weight of 3,000 to 20,000 is provided. In addition to chloroprene and unsaturated glycidyl ester, the monomers used in the present invention may contain one or more other monomers that can be copolymerized with chloroprene. However, the amount of these monomers is preferably 50% by weight or less based on chloroprene. Monomers that can be used are those having at least one H ₂ C=C group, and preferred examples include styrene,
Examples include vinyl compounds such as acrylonitrile, acrylic acid and its esters, methacrylic acid and its esters, and conjugated dienes such as 1,3-butadiene, isoprene, and 2,3-dichlorobutadiene-1,3. The use of 2,3-dichlorobutadiene-1,3 or isoprene as these comonomers is particularly effective in keeping the polymer sufficiently fluid during storage; When an unsaturated carboxylic acid monomer such as an acid is copolymerized, the carboxyl content in the resulting liquid polymer can be increased. The unsaturated glycidyl ester used in the present invention has the formula (In the formula, R is hydrogen or an alkyl group having 1 to 2 carbon atoms.) A typical example thereof is glycidyl methacrylate. The amount of unsaturated glycidyl ester to be used varies depending on the molecular weight of the desired polymer or the number of bonded epoxy groups, and therefore is influenced by the type and amount of mercaptocarboxylic acid as a chain transfer agent. It ranges from 0.5 to 15% of the parts by weight.
For example, the number average molecular weight of the liquid polymer is 3000 or
10,000, the amount of glycidyl ester used is about 4 to 15% or 1 to 4% of the total monomer weight, and the higher the molecular weight of the polymer, the smaller the amount used. good. Any mercaptocarboxylic acid used in the present invention can be used as long as it has at least one mercapto group and at least one carboxyl group in its molecule and is soluble in the solution polymerization system used. Examples include thioglycolic acid, 2-
Examples include mercaptopropionic acid, thiolactic acid, and thiomalic acid. Among these, thioglycolic acid is particularly preferred in terms of its solubility and economical efficiency.
Since these mercaptocarboxylic acids are strong chain transfer agents, they play a dominant role in the molecular weight of the liquid polymer. The number average molecular weight of the liquid polymer produced by the method of the present invention is in the range of 3,000 to 20,000 due to the requirements for processability and self-curing properties. That is, liquid polymers below this range have very good fluidity, but the lower the molecular weight, the slower the apparent curing reaction even in the presence of an appropriate curing agent, and the self-curing property decreases. Further, liquid polymers exceeding this range have excellent self-curing properties, but have drawbacks such as a marked decrease in fluidity. Therefore, the amount of these mercaptocarboxylic acids used must be such that the molecular weight of the polymer falls within the above-mentioned appropriate range, and the amount is 0.3 to 3.5 parts by weight of thioglycolic acid per 100 parts by weight of the monomer. limited to substantially equivalent ranges of amounts. If it deviates from this range, the obtained polymer will be difficult to achieve the object of the present invention in terms of either its fluidity or self-curing properties. In the present invention, the method of adding the mercaptocarboxylic acid into the polymerization system may be either a method of adding it all at once at the beginning of the polymerization or a method of adding it in portions at favorable times during the polymerization time, but in particular, the method of adding the mercaptocarboxylic acid into the polymerization system may be The polymerization rate can be easily controlled by adding mercaptocarboxylic acid and the monomer into the polymerization system so that the weight ratio of mercaptocarboxylic acid and the monomer is constant. This is preferable from the viewpoints of improving acid chain transfer efficiency and polymer yield, and uniformity of molecular weight of the polymer and distribution of terminal carboxyl groups. The number of epoxy groups in the liquid chloroprene polymer obtained by the present invention is in the range of 1 to 2.5 per average molecular chain. Below this range, the self-curing properties of the polymer tend to decrease rapidly;
Moreover, if it exceeds this range, not only is it economically disadvantageous, but also no significant effect of improving curability is observed. In the present invention, the monomer is solution-polymerized in an organic solvent. and must be miscible with the mercaptocarboxylic acid. Further, it is necessary that the organic solvent can be recovered by a conventional method in the separation process of the produced liquid polymer, and the organic solvent is selected from aromatic hydrocarbons, aliphatic halogenated hydrocarbons, and cyclic ethers. It is limited to organic solvents or mixtures thereof with a boiling point of 150°C or less under normal pressure. Since the liquid polymer according to the present invention is a viscous liquid, it is quite difficult to substantially completely remove the solvent from the polymer solution. The solvent must not exceed Examples of typical solvents used in the present invention are benzene,
These include toluene, xylene, carbon tetrachloride, chloroform, tetrahydrofuran, and dioxane. The amount of solvent is 20 to 200 parts by weight of total monomers.
If the amount is less than 20 parts by weight, it will be difficult to control the heat generated during the polymerization reaction, and if it is more than 200 parts by weight, the reaction rate will be greatly reduced, making it difficult to put it into practical use. Since the polymerization reaction according to the present invention is promoted by a conventional free radical mechanism, common techniques for radical polymerization systems with regard to time, temperature, concentration and other reaction conditions, selection of polymerization initiator, etc. can be utilized. Typical examples of polymerization initiators used include azo compounds such as azobisisobutyronitrile and organic peroxides such as benzoyl peroxide. The polymerization reaction takes place between 0 and 100°C, especially between 40°C and 100°C.
Preferably it is carried out at a temperature of between 60°C. At temperatures lower than 0°C, the polymerization reaction tends to be generally too slow even if a particularly low-temperature active polymerization initiator is used, and at temperatures higher than 100°C, it is difficult to control the reaction.
The conversion rate of monomer to polymer is usually preferably 60 to 80%, but it can be increased to 90% or more. The polymerization reaction can be stopped at a desired point by adding a polymerization terminator such as p-tert-butylcatechol. The number average molecular weight of the liquid chloroprene polymer produced by the method of the present invention is 3,000 to 20,000, and the polymer contains at least one carboxyl group and 1 to 2.5 epoxy groups in one molecule.

It has the following formula and can easily self-cure into an elastomer with the following curing agent. As the curing agent, any of reaction accelerators between carboxyl groups and epoxy groups, ring-opening polymerization accelerators for epoxy groups, coupling agents between carboxyl groups, etc. can be used, but the following basic substances are particularly suitable. Namely, hydroxides of alkali metals such as caustic soda and caustic potash, and pyridine, quinoline, isoquinoline, N,N-dimethylcyclohexylamine, N-ethyl-3,5-dimethylmonophorine,
Tertiary amines such as N-(β-hydroxyethyl)amine, α-picoline, triethylamine, N-ethylphorphorine, tri-n-butylamine, 2,4,6-tri-(dimethylaminomethyl)phenol, etc. be. The amount of these curing agents used is usually about 0.002 to 5 parts by weight, preferably about 0.05 to 2 parts by weight, per 100 parts by weight of the polymer. In addition to the above curing agents, conventional vulcanization accelerators for chloroprene polymers, such as ethylene thiourea,
It is also possible to use N,N'-diethylthiourea, N,N'-diphenylthiourea, di-o-tolylguanidine, dicatecholborate di-O-tolylguanidine, etc. in combination. The self-curing polymer is usually cured at a temperature range of -10 to 200°C, and the desired curing temperature and speed can be achieved by selecting the type and amount of the curing agent and curing accelerator. Curable. Hardener systems that harden easily, especially at room temperature, such as 3 above.
When a class amine type is used, it can be used for a wide range of purposes. Furthermore, because of its unterminated carboxyl group, the polymer of the present invention can easily form chelates with common polyvalent metal oxides such as zinc white and magnesia, and can also react with isocyanates to form amide bonds. It is also possible to do so. It is also possible to form an oxazolindone ring by reacting a polyfunctional isocyanate with the epoxide of the polymer. Of course, if necessary for practical purposes, fillers such as titanium dioxide, calcium carbonate, clay, and carbon black, which are ordinary compound ingredients, may be added.
Petroleum based oils, softeners such as phthalate esters and tars, resins such as phenol resins, coumaron indene resins, epoxy resins, aromatic petroleum resins, bituminous materials such as straight asphalt and blown asphalt, and oxidation inhibitors such as hindered phenols. It is possible to incorporate solvents as agents and viscosity modifiers for the compound. The polymer obtained by the present invention has excellent compatibility and reactivity with various polymeric materials due to its carboxyl group and epoxide, so it can be used with thermosetting resins such as epoxy resins, phenolic resins, coumaron resins, and petroleum-based resins. It is also useful as a flexibility imparting agent for plastic or thermoplastic resins. It is particularly effective in improving the impact resistance and peel adhesion of epoxy resins. In addition, by utilizing the self-curing property and/or chelate-forming ability of this polymer with metal oxides, it can be used as one-component or two-component compositions for elastic sealants, adhesives, lining materials, coating materials, paints, and adhesives. Not only can it be suitably used for agents, sponge materials, and other industrial materials, but it can also be effectively used as a reactive softener for solid rubbers, particularly chloroprene rubber, chlorosulfonated polyethylene, and the like. Furthermore, the polymer can be used not only as a binder for fine powder, but also as a variety of flame-retardant compositions by taking advantage of its flame-retardant properties. EXAMPLES Examples, reference examples, and comparative examples are shown below to explain the present invention in more detail. Parts and percentages herein are based on weight unless otherwise specified. Example 1 In a reaction vessel equipped with a stirrer, 96 parts of chloroprene, 4 parts of glycidyl methacrylate (trade name of NOF Corporation "Blemmer G", hereinafter abbreviated as GMA),
After charging a homogeneous transparent liquid consisting of 50 parts of toluene and 1.5 parts of thioglycolic acid and raising the temperature to 55°C, 1.5 parts of a toluene solution containing 0.5 parts of α, α′-azobis-2,4-dimethylvaleronitrile as a polymerization initiator was added.
part was added to initiate polymerization. 20 hours later p-
Polymerization was stopped by adding 1 part of a toluene solution containing 0.02 part of tert-butylcatechol. The conversion rate of chloroprene and GMA to polymer was 77.2%, respectively.
It was 81.5%. Next, a large excess of methanol was added, the polymer was isolated, and the purification procedure of dissolving it in benzene and coagulating it with methanol was repeated three times.
The residual solvent was evaporated and the polymer was isolated under the following conditions. This polymer was pale yellow, transparent, and had a Bruckfield viscosity of 337,000 cps when measured at 25°C.
The amount of residual solvent in the produced polymer was determined by gas chromatography to be 0.1% or less. The result of infrared absorption spectrum analysis of this polymer was 1720 cm ^-1
(

[Formula] based on the group) and 910cm ^-1 (

Characteristic absorption based on the glycidyl ester structure of [Formula] group) was confirmed. Furthermore, a calibration curve was created using an infrared absorption spectrum from a homopolymer of GMA and a chloroprene homopolymer obtained by modification with thioglycolic acid, and the amount of GMA in the polymer was determined to be 4.20%. Next, a benzene solution of the polymer was subjected to neutralization titration with a caustic methanol solution to measure the carboxyl content, which was found to be 1.19%. On the other hand, the number average molecular weight of the polymer determined using an everiometer was 3820. According to the above analysis results, the average number of carboxyl groups per molecule of this polymer is 1.01, and the average number of epoxy groups is
1.13 pieces were requested. The polymer obtained here will be referred to as Polymer A. Example 2 84 parts of chloroprene, 2,3-dichlorobutadiene-1, instead of 96 parts of chloroprene and 4 parts of GMA
Polymerization and purification were performed using the same recipe as in Example 1 except that 8 parts of GMA and 8 parts of GMA were used to obtain a polymer.
Chloroprene, 2,3-dichlorobutadiene
The polymer conversion rates of 1, 3 and GMA were 78.0%, respectively.
They were 98.2% and 80.6%. This polymer was measured in the same manner as in Example 1, and the number average molecular weight was 4160, and the carboxyl group and GMA contents were 1.09% and 7.87%, respectively. From the above analysis results, the average number of carboxyl groups per molecule of this polymer is 1.01, and the average number of epoxy groups is
2.31 pieces were required. The polymer thus obtained is referred to as Polymer B. Example 3 A polymer was obtained in the same manner as in Example except that 0.75 parts of thioglycolic acid was used instead of 1.5 parts, and 98 parts of chloroprene and 2 parts of GAM were used instead of 96 parts of chloroprene and 4 parts of GMA. Next, the same analysis as in Example 1 was performed, and the number average molecular weight was
6250, Bruckfield viscosity at 25℃
1420000 cps, the average number of carboxyl groups and epoxy groups per polymer molecule is 1.00 and 1.02, respectively.
It was individual. The polymer obtained here is referred to as Polymer C. Comparative Examples 1 to 3 Polymers D, E, and F were obtained in the same manner as in Example 1, except that the monomer composition and the type and amount of the chain transfer agent were changed as shown in Table 1. These polymers were also subjected to various analyzes according to the measuring method described in Example 1, and the results are summarized in Table 1.

[Table] Polymers D, E, and F are polymers containing only carboxyl groups in the molecule, polymers containing only epoxy groups, and polymers containing both carboxyl groups and epoxy groups, but the content is Less polymer. Reference example 1 10 parts of zinc white, 30 parts of SRF carbon black, and 2 parts of 2,4,6-tris(dimethylaminomethyl)phenol were added to 100 parts each of polymers A, B, D, E, and F using a paint mill. This mixture was degassed by pressing at room temperature using a mold with a thickness of 2 mm, and the curing state after standing at 50° C. for 48 hours was compared. As a result, polymers A and B formed a rubber-like cured sheet, whereas polymers D, E, and F showed increased viscosity but did not form a cured product. Reference example 2 100 parts of polymer c, 8 parts of Epicote 828 (Ciel Chemical Co., Ltd. epoxy resin trade name), 10 parts of zinc white,
30 parts of SRF carbon black and 1.5 parts of 2,4,6-tris(dimethylaminomethyl)phenol were kneaded using a paint mill, and a press sheet obtained in the same manner as in Reference Example 1 was left standing at room temperature for 7 days. A cured product was produced. The tensile strength of this product was 88 Kg/cm ² and the elongation at break was 320%. Reference Example 3 A press sheet was obtained in the same manner as in Reference Example 1 from a compound obtained by blending 100 parts of Polymer B with 10 parts of zinc white using a paint mill. This product formed a rubber-like cured sheet by standing at room temperature for 2 days, but it had a weak tensile strength of 4 kg/cm ² . When this sheet was further heat treated at 150°C for 30 minutes, the tensile strength was improved to 35Kg/cm ² .

Claims (1)

[Scope of Claims] 1 Chloroprene monomer alone or together with a monomer copolymerizable therewith with the formula (In the formula, R is hydrogen or an alkyl group having 1 to 2 carbon atoms). Aromatic hydrocarbons, aliphatic halogenated, having a boiling point of 20 to 200 parts by weight at normal pressure of 150°C or less per 100 parts by weight of total monomers, in the presence of a mercaptocarboxylic acid in an equivalent amount A method for producing a self-curing liquid chloroprene-based heavy material, which comprises copolymerizing in an organic solvent selected from hydrocarbons and cyclic ethers. 2 The monomer that can be copolymerized with chloroprene is 2,3
-dichlorobutadiene-1,3 A method for producing the polymer according to claim 1, which is -dichlorobutadiene-1,3. 3. The method for producing a polymer according to claim 1, using thioglycolic acid as the mercaptocarboxylic acid.