JPS632965B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a liquid chloroprene polymer having a carboxyl group and an epoxy group in the molecule, and more specifically to a novel liquid chloroprene polymer that has excellent fluidity and reactivity and has good compatibility with various resins. Concerning the manufacturing method. Various liquid chloroprene-based polymers have been known, but their compatibility with general-purpose epoxy resins, urethane prepolymers, and their raw materials such as polyether-type glycols and polyester resins is generally not good, and they are not suitable for adhesives. This problem has often caused problems in the development of adhesives, paints, sealants, etc. In view of these points, the inventor has made extensive studies, and
The present inventors discovered a method for producing a type of liquid chloroprene polymer that greatly improves the compatibility of conventional liquid chloroprene polymers with various resins and has excellent fluidity and reactivity, leading to the completion of the present invention. . One object of the present invention is to develop a resin modification material that has excellent compatibility with various resins, can improve the flexibility, tackiness, adhesion, flame retardance, etc. of resins, and has excellent processability and reactivity. An object of the present invention is to provide a method for producing a specific liquid chloroprene polymer. Another object of the present invention is that it can be mixed with general-purpose epoxy resins, especially bisphenol-epichlorohydrin condensates, in arbitrary proportions, impart flexibility to the cured product of the epoxy resin, and greatly improve impact resistance and peel adhesion. An object of the present invention is to provide a method for producing a novel liquid chloroprene-based polymer which can be improved in the following manner and is particularly excellent as a modifier for a room-temperature curing epoxy resin composition. That is, the present invention uses a chloroprene monomer alone or together with a monomer copolymerizable therewith with the formula (However, in the formula, R is hydrogen or an alkyl group having 1 to 2 carbon atoms.) Aromatic carbonization with a boiling point of 150°C or less under normal pressure in the presence of mercaptocarboxylic acid in an amount substantially equivalent to the amount of thioglycolic acid, and in an amount of 20 to 200 parts by weight per 100 parts by weight of total monomers. The present invention provides a method for producing a liquid chloroprene polymer, which comprises copolymerizing in an organic solvent selected from hydrogen, aliphatic halogenated hydrocarbons, and cyclic ethers. According to the production method of the present invention, the main chain consists of repeating units of chloroprene, and the molecule contains at least
0.5 to 2.5 epoxy groups derived from unsaturated glycidyl ester monomers and at least one epoxy group at the end of the molecule.
A liquid chloroprene polymer having carboxyl groups derived from mercaptocarboxylic acids and a number average molecular weight of 500 or more and less than 3000 is obtained. 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. The monomers used are those having at least one H ₂ C=C group, and preferred examples include styrene, acrylonitrile, acrylic acid and its esters,
Vinyl compounds such as methacrylic acid and its esters, 1,3-butadiene, isoprene, 2,3-
Examples include conjugated dienes such as dichlorobutadiene-1.3. As these copolymerized monomers, 2,3-
The use of dichlorobutadiene-1,3 or isoprene is particularly effective in keeping the polymer well-flowed during storage, and it is also effective in keeping unsaturated carboxylic acid monomers such as acrylic acid and methacrylic acid together. When polymerized, the carboxyl content in the desired 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 target polymer or the number of bonded epoxy groups, and is influenced by the type and amount of mercaptocarboxylic acid as a chain transfer agent. It is in the range of 2 to 50% of the monomer weight.
For example, in a polymerization recipe in which the number average molecular weight of the polymer is 1000, the amount of the glycidyl ester used is about 6 to 30% of the total monomer weight; The ester is approx.
The amount is 2.4 to 12%, and the higher the molecular weight of the polymer, the smaller the amount needed to be used. The mercaptocarboxylic acid used in the present invention has at least one mercapto group and at least one carboxyl group in its molecule, and any mercaptocarboxylic acid can be used as long as it is soluble in the solution polymerization system used. Suitable examples include thioglycolic acid,
Examples include 2-mercaptopropionic acid, thiolactic acid, and thiomalic acid. Among these, thioglycolic acid is particularly preferred in terms of its solubility and economical efficiency. Since these mercapto 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 to be produced by the method of the present invention is in the range of 500 or more and less than 3000 in view of the requirements for its fluidity and compatibility and co-reactivity with various resins. In other words, liquid polymers below this range have good fluidity and compatibility with resins, but not only do they tend to be less effective in imparting elasticity and improving toughness to resins, but they are also disadvantageous in terms of manufacturing costs. Become. Moreover, if the molecular weight exceeds the above range, the viscosity of the liquid polymer increases, resulting in a disadvantage that the processability during resin blending and the workability of the blended product are reduced. 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 should exceed 3.5 parts by weight of thioglycolic acid per 100 parts by weight of the monomer25. The amount is limited to a range substantially equivalent to parts by weight or less. If it deviates from this range, the obtained polymer will be difficult to achieve the object of the present invention in terms of its fluidity or the modifying effect on the resin. 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 the molecular weight of the polymer or the 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 0.5 to 2.5 per average molecular chain. Below this range, the compatibility and curing reactivity of the polymer with various resins tends to decrease rapidly, and when it exceeds this range, it is not only economically disadvantageous but also significantly improved in compatibility and curability. No effect was 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 include benzene, toluene, xylene, carbon tetrachloride, chloroform, tetrahydrofuran, dioxane, and the like. The amount of solvent is 20-200 parts per 100 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 drop significantly, 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 regarding 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 also 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 500 or more and less than 3000, and the polymer contains at least one carboxyl group and 0.5 to 2.5 epoxy groups in each molecule.

It has [Formula] and is used as a reaction accelerator between a carboxyl group and an epoxy group, a ring-opening polymerization accelerator for an epoxy group, a coupling agent between carboxyl groups, etc., such as caustic soda,
Hydroxides of alkali metals such as caustic potash and pyridine, quinoline, isoquinoline, N.N-dimethylcyclohexylamine, N-ethyl-3.5
- tertiary esters such as dimethylmorpholine, N-(β-hydroxyethyl)amine, α-picoline, triethylamine, N-ethylphorphorine, tri-n-butylamine, 2,4,6-tri-(dimethylaminomethyl)phenol; Not only can it be easily compatible with and co-cure with various resins having carboxyl groups and epoxy groups in the presence of a basic substance such as a basic amine, but also self-curing can occur between the polymers. Furthermore, because of the terminal carboxyl group, the polymer produced by the present invention can easily form chelates with common polyvalent metal oxides such as zinc and magnesia, and can also react with isocyanates to form amide bonds. It is also possible to form It is also possible to form an oxazolidone ring by reacting the polymer with an epoxide in the presence of a catalyst such as a tertiary amine or quaternary ammonium, and to cure the polymer. Resins that can be modified by the polymer produced according to the present invention include the following preferred groups based on their compatibility or co-reactivity. Namely, liquid or solid epoxy resins, phenolic resins, polyterpene resins, coumaron/intene resins, xylene resins, aromatic petroleum resins, urethane resins, rosin resins, vinyl chloride pastes, chlorinated rubber, chlorinated polyethylene, polyester resins, and asphalt. etc., but are not limited to these. The modification effect of the polymer according to the present invention on these resins can be broadly divided into improvements in processability and resin performance, and the latter is particularly important for improving impact resistance by imparting flexibility, improving peel adhesion strength, and smoothing metal, glass, etc. A major feature is that it brings about multiple improvement effects such as improved adhesion to surface materials, and improved adhesion to oily and wet surfaces. Also, by utilizing the reactivity and adhesive properties of this polymer, it can be suitably used as one-component or two-component compositions for elastic sealants, adhesives, lining materials, coating materials, paints, adhesives, sponge materials, etc. Not only can it be used, but it can also be effectively used as a reactive softener for solid rubber, particularly chloroprene rubber, chlorosulfonated polyethylene, and the like. Furthermore, the polymer can be used not only as a binder in the form of fine powder, but also as a variety of flame-retardant compositions by taking advantage of its flame-retardant properties. Of course, if necessary for practical purposes, ordinary compound ingredients such as titanium dioxide, calcium carbonate, clay, fillers such as carbon black, petroleum oils, softeners such as phthalate esters and tar,
Antioxidants such as hindered fluorescein, chloroprene rubber vulcanization accelerators such as ethylene thiourea,
It is possible to incorporate solvents as viscosity modifiers for the compound. 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, a homogeneous solution consisting of 94 parts of chloroprene, 6 parts of glycidyl methacrylate (trade name of NOF Corporation "Blemmer G", hereinafter abbreviated as GMA), 50 parts of toluene, and 5 parts of thioglycolic acid was added. After charging the transparent liquid and raising the temperature to 55℃, α・α′-azobis-2・4 was added as a polymerization initiator.
-1.5 parts of a toluene solution containing 0.5 parts of dimethylvaleronitrile was added to initiate polymerization. After 20 hours, 1 part of a toluene solution containing 0.02 part of P-tert-butylcatechol was added to stop the polymerization. The conversion rates of chloroprene and GMA to polymer are respectively
The percentages were 78.9% and 81.0%. Next, a large excess of methanol was added, the polymer was isolated, and the purification process of dissolving it in benzene and coagulating it with methanol was repeated three times.
The residual solvent was evaporated under Hg abs conditions and the polymer was isolated. This polymer was pale yellow, transparent, and had a Bruckfield viscosity of 41,500 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 results of infrared absorption spectrum analysis of this polymer
1720cm ^-1 (

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

Characteristic absorption based on the glycidyl ester structure of [formula] (base) 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 4.70%. Next, a benzene solution of the polymer was subjected to neutralization titration with a caustic potash-methanol solution to measure the carboxyl content, which was found to be 2.90%. On the other hand, the number average molecular weight of the polymer determined using an everiometer was 1570. From the above analysis results, it was determined that the average number of carboxyl groups per molecule of this polymer was 1.01, and the average number of epoxy groups was 0.52. The polymer obtained here will be referred to as Polymer A. Example 2 80 parts of chloroprene and 2,3-dichlorobutadiene instead of 94 parts of chloroprene and 6 parts of GMA
Polymerization and purification were performed using the same recipe as in Example 1 except that 8 parts of 1.3 and 12 parts of GMA were used to obtain a polymer. The polymer conversion rates of chloroprene, 2,3-dichlorobutadiene-1,3 and GMA were each 78.0.
%, 99.0% and 79.5%. As a result of measuring this polymer in the same manner as in Example 1, the contents of carboxyl groups with a number average molecular weight of 2050 and GMA were 2.25% and 10.9%, respectively. From the above analysis results, the average number of carboxyl groups per molecule of this polymer is 1.03, and the average number of epoxy groups is
It was asked for 1.57 pieces. The polymer thus obtained is referred to as Polymer B. Example 3 Using 10 parts instead of 5 parts of thioglycolic acid,
A polymer was also obtained in the same manner as in Example 1, except that 80 parts of chloroprene and 20 parts of GMA were used instead of 94 parts of chloroprene and 6 parts of GMA. Next, Example 1
When a similar analysis was performed, the number average molecular weight was
1060, Burtskfield viscosity 15100cps at 25℃,
The average numbers of carboxyl groups and epoxy groups per polymer molecule were 1.03 and 1.40, respectively. 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 composition of the monomers 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】

[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 and epoxy groups, but whose molecular weight is This is a polymer that goes beyond the scope of the invention. Reference example: Polymers A, B, E, and F are each blended with an equal amount of a general-purpose epoxy resin or a polyether type diol that is a raw material for polyurethane, and the thoroughly mixed solution is placed in a glass test tube and placed in a constant temperature bath at 50°C. The compatibility was evaluated by observing the mixed state after standing for 7 days. The results are summarized in Table 1.

[Table] Reference Example 2 Table 2 summarizes the results of comparing the cured products of Polymers C and D as epoxy resin modifiers according to the following formulations. From these results, it is clear that when the polymer according to the present invention is used, not only the effect of imparting flexibility to the epoxy resin is excellent, but also the toughness is improved. Here, Test No. 1 and No. 3 are comparative examples, respectively.

【table】

【table】

Claims (1)

[Claims] 1 A chloroprene monomer, alone or together with a monomer that can be copolymerized therewith, has the formula (However, in the formula, R is hydrogen or an alkyl group having 1 to 2 carbon atoms.) Aromatic carbonization with a boiling point of 150°C or less under normal pressure in the presence of mercaptocarboxylic acid in an amount substantially equivalent to the amount of thioglycolic acid, and in an amount of 20 to 200 parts by weight per 100 parts by weight of total monomers. A method for producing a liquid chloroprene polymer, which comprises copolymerizing in an organic solvent selected from hydrogen, aliphatic halogenated hydrocarbons, and cyclic ethers. 2 Monomers that can be copolymerized with chloroprene are 2.3
-dichlorobutadiene-1.3. 3. The manufacturing method according to claim 1 or 2, in which thioglycolic acid is used as the mercaptocarboxylic acid.