JPH0121161B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a novel hot-melt and reactive copolymer, and more specifically to a method for producing a new hot-melt and reactive copolymer, and more specifically, a low molecular weight copolymer that can form a rubber-like elastic body by vulcanization into which chemically active groups have been introduced. 2,3-dichlorobutadiene-
The present invention relates to a method for producing a copolymer of 1,3 and chloroprene. Conventionally, 2,3-dichlorobutadiene-1,3
Although the homopolymers and copolymers of chloroprene and their production methods are widely known, 2,3-dichlorobutadiene-1,3
A low molecular weight copolymer with chloroprene having a functional group as a main component was not known at all. As a result of repeated detailed studies on the copolymerization reaction of 2,3-dichlorobutadiene-1,3 and chloroprene in a solution polymerization system and the resulting copolymer, the present inventor has developed a new hot-melt and vulcanizable copolymer. The inventors discovered that a polymer can be produced, leading to the present invention. The purpose of the present invention is to produce a new polymer, which is a so-called hot-melt type polymer that is solid at room temperature due to its crystallinity, but melts by heating and has sufficient fluidity, and is curable by a functional group introduced into the molecule. It is to provide law. According to the present invention, the weight composition ratio of the monomer units constituting the polymer is 2,3-
Dichlorobutadiene-1,3/chloroprene=
Provided is a low molecular weight copolymer having a number average molecular weight of 65/33 to 90/10, a number average molecular weight of 1000 to 10000, and having at least one bromine atom in the molecule. Ru. It has become clear that this copolymer can be produced by producing it in a solution polymerization system under specific conditions as shown below. That is, the weight ratio of the monomer mixture is 2,3-dichlorobutadiene-1,3/chloroprene = 55/45 ~
A monomer mixture in the range of 90/10 in the presence of 1 to 20 parts by weight of a specific chain transfer agent per 100 parts by weight and in an organic solvent of 20 to 400 parts by weight per 100 parts by weight of total monomers. This is a manufacturing method characterized by copolymerizing with The specific chain transfer agent is a halogenated hydrocarbon having at least one bromine atom in the molecule, and is used not only to lower the molecular weight of the copolymer but also to transfer the copolymer using the bromine atom as a functional group. It is an essential component to be introduced into the polymer. Representative examples of halogenated hydrocarbons as chain transfer agents include, but are not limited to, monobromotrichloromethane, dibromodichloromethane, tribromochloromethane, carbon tetrabromide, and dibromodichloroethane. The amount of chain transfer agent used in the present invention is 100% of the total monomer.
It is limited to a range of 1 to 20 parts by weight, and if it deviates from this range, the molecular weight of the resulting copolymer tends to fall outside the limited range of the present invention, which is not preferred. The ratio of the monomers, which are the main components used in the present invention, is limited to a range of 2,3-dichlorobutadiene-1,3/chloroprene=55/45 to 90/10 in weight percent. When this ratio is smaller than 55/45, that is, when the number of chloroprene monomer units in the copolymer increases, the room temperature crystallinity of the copolymer decreases significantly and the copolymer becomes a room temperature liquid. On the other hand, if this ratio is greater than 90/10, 2,3-dichlorobutadiene-
Since it approaches a homopolymer of 1 and 3, it is crystalline at room temperature, but its melting point is high, which not only reduces workability but also makes it extremely difficult to dissolve in organic solvents at room temperature, making it difficult to achieve homogeneous polymerization. production becomes difficult. In the present invention, the usage ratio of each monomer is 2,3
The reason for limiting the weight ratio of -dichlorobutadiene-1,3/chloroprene to the range of 55/45 to 90/10 is that the following cannot be achieved simultaneously with each homopolymer of 2,3-dichlorobutadiene-1,3 or chloroprene This is to satisfy all the merits of That is, (1) the thermal melting temperature is significantly lower than that of a homopolymer of 2,3-dichlorobutadiene-1,3, and workability during hot melting is practically improved. (2) Crystallinity at room temperature is substantially maintained. (3) Unlike the homopolymer of 2,3-dichlorobutadiene-1,3, it has excellent solubility in organic solvents. (4) Vulcanization reactivity based on the chloroprene monomer unit is maintained. In the present invention, the monomers to be copolymerized include 2,3-dichlorobutadiene-1,3 and chloroprene, as well as one or two other monomers that can be copolymerized with these monomers. Although more than one species may be contained, it is preferable that the amount of these monomers is 10% by weight or less based on the monomer mixture of 2,3-dichlorobutadiene-1,3 and chloroprene. The monomers that can be used are those having at least one H ₂ C=C group, and preferred examples include styrene, acrylonitrile, methacrylic acid, vinyl compounds such as methacrylic esters, isoprene, 1,3 - Conjugated dienes such as butadiene. When the amount of these monomers used exceeds the above 10% by weight, 2,3-dichlorobutadiene-1,3/
The crystallinity of the chloroprene copolymer tends to decrease, and the copolymer tends to lose its hot melt properties. The reason why the copolymer obtained by the method of the present invention exhibits hot melt properties, that is, relatively sharp thermal melting behavior, is because 2,
Since it is believed to be based on a chain block of 3-dichlorobutadiene-1,3, the chain block tends to be disturbed by copolymerization of multicomponent monomers. Therefore, 2,3-dichlorobutadiene-1,3/
Even in the two-component copolymerization of chloroprene, the method of adding monomers to the polymerization system influences the formation of the chain block. Generally, it is desirable for the present invention to maintain the polymerization system so that the 2,3-dichlorobutadiene-1,3/chloroprene monomer composition is within a certain range. The present invention follows a method in which monomers are solution-polymerized in an organic solvent, but the organic solvent used is inert to both the starting materials and the reaction products, and in order to carry out the reaction in a homogeneous system, these organic solvents are used. It is desirable that the organic solvent be a good solvent for aromatic hydrocarbons, aliphatic halogenated carbonates, etc. It is limited to any organic solvent selected from hydrogen and cyclic ethers with a boiling point of 150°C or less under normal pressure, or a mixture thereof. In the present invention, the resulting polymer solution is very viscous, so in order to substantially completely remove the solvent from the polymer solution, the solvent must have a boiling point not exceeding approximately 150° C. under normal pressure. Examples of typical solvents used in the present invention include benzene, toluene, xylene, carbon tetrachloride, chloroform, trichloroethylene, tetrahydrofuran, dioxane, and the like. The amount of solvent is the total monomer
It is in the range of 20 to 400 parts by weight per 100 parts by weight, and if it is less than this range, it is difficult to control the heat generated during the polymerization reaction. In the case of a copolymer having a high percentage by weight, if the polymerization reaction is carried out at 80° C. or lower, there is a tendency for a part of the copolymer to precipitate in the system. Moreover, when the above range is exceeded, the reaction rate decreases 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 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, and in particular polymerization initiators having terminal functional groups, such as 4 ,4'-azobis-(4-cyanovaleric acid)
Alternatively, when an initiator having a functional group such as 4,4'-azobis-(4-cyano-n-bentanol) is used, a terminal functional group such as a carboxyl group or a hydroxyl group can be introduced. Polymerization reaction is 0~
Preference is given to carrying out between 100°C, especially between 40 and 80°C. At temperatures lower than 0°C, the polymerization reaction tends to be generally too slow even if a polymerization initiator active at low temperatures 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 60-90%. To stop the polymerization reaction, P-
The polymerization can be stopped at a desired point by adding a polymerization terminator such as tert-butylcatechol or by cooling the polymerization solution. The number average molecular weight of the copolymer obtained by the method of the present invention is preferably in the range of 1,000 to 10,000. If it is less than this range, the copolymer will have excellent hot-melt properties, but the vulcanization reactivity will be markedly reduced, and if it exceeds this range, the vulcanization reactivity will be high, but the hot-melt properties will be poor, making it impractical for practical use. It tends to be difficult. The copolymer obtained by the method of the present invention has at least one bromine atom in the molecule, which has chemical reactivity. It also has reactivity. Therefore, by utilizing these chemical reactivities, reactions such as chain extension or crosslinking can be easily promoted. In order to have sufficient chemical reactivity such as chain extension or crosslinking, the copolymer needs at least one bromine atom, and preferably has 1 to 4 bromine atoms. When promotion of chain extension or crosslinking reaction in the copolymer is required, it is preferable to use a polyfunctional amine compound as a reaction accelerator. Suitable reaction promoters include polyfunctional primary, secondary and tertiary amines and their alkylated derivatives. Examples include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine and hexamethylenediamine and their partially or fully alkylated derivatives such as methyl or ethylated derivatives. Examples of such derivatives are N,N,N',N'-tetramethylhexamethylenediamine and N,N,N',N'-tetramethylethylenediamine. The amount of the reaction accelerator is preferably 3 to 20 parts by weight per 100 parts by weight of the copolymer, and the best results are particularly obtained when 5 to 10 parts are used. The thermal melting temperature of the copolymer obtained by the method of the present invention is influenced by the composition, molecular weight, type of functional group, etc. of the monomer units that are the constituent components.
It is usually between 80 and 130℃, and is 30 to
The temperature will drop by about 80℃. Therefore, the copolymer easily melts when heated, but quickly solidifies when cooled to room temperature, and in the presence of a suitable crosslinking agent, chain extension or crosslinking reaction is promoted during hot melting. Due to the above characteristics, the copolymer obtained by the method of the present invention can be effectively used in a wide range of applications. For example, by utilizing its hot-melt properties and reactivity, it is used in fields such as solvent-free hot-melt adhesives, lining materials, and coating materials, and by utilizing its reactivity and room-temperature crystallinity, it is used in the fields of solvent-based adhesives, It can be effectively used in primers, paints, etc., and can also be used as an intermediate raw material for brominated adhesive compositions. In addition, the copolymer obtained by the present invention is easily soluble in toluene even at room temperature, and can be formed into a rubber-like elastic body by vulcanization, so it can be used in solvent-based adhesives, primers, and hot melts that are endowed with rubber elasticity. It can be particularly suitably used for adhesives and the like. In addition, if necessary for practical use in these applications, fillers such as titanium white, calcium carbonate, clay, and carbon black, which are common compound ingredients, may be added.
Petroleum-based oils, phthalate esters, softening agents such as tar, resins such as phenol resin, coumaron indene resin, petroleum-based aromatic resins, bituminous substances such as straight asphalt, blown asphalt, antioxidants such as hindered phenol. It is also possible to add coloring additives and the like. Examples and reference examples are shown below. where part and %
Based on weight unless otherwise specified. Example 1 A homogeneous mixed solution consisting of 60 parts of 2,3-dichlorobutadiene-1,3, 40 parts of chloroprene, 50 parts of toluene, and 2 parts of carbon tetrabromide was placed in a reaction vessel equipped with a stirrer and heated to 55°C. After warming, 1.5 parts of a toluene solution containing 0.5 parts of α,α'-azobis-2,4-dimethylvaleronitrile as a polymerization initiator was added to initiate polymerization. After the viscosity of the reaction solution increased during the polymerization time of 7 hours, P-tert-butylcatechol
1 part of toluene solution containing 0.02 part was added, and the mixture was cooled to room temperature to stop the polymerization. The conversion rates of 2,3-dichlorobutadiene-1,3 and chloroprene into polymers were 87.0% and 63.1%, respectively. Next, a large excess of methanol was added to isolate the polymer, and the purification operation of dissolving in benzene and coagulating with methanol was repeated three times.The resulting pale yellow polymer was again made into a 50% benzene solution, and this was °C, 1-2
The residual solvent was removed using a thin film evaporator under conditions of mmHgabs. The resulting polymer changed from liquid to solid while being cooled to room temperature. The polymer obtained here is referred to as Polymer A. Example 2 A copolymer of 2,3-dichlorobutadiene-1,3 and chloroprene was produced in the same manner as in Example 1, except that 1.8 parts of monobromotrichloromethane was used instead of 2 parts of carbon tetrabromide. . The polymer obtained here is referred to as Polymer B. Reference Example In order to evaluate the hot melt properties and reactivity of the polymers obtained in Examples 1 and 2, the following formulation was used.
The formulations were made using a paint mill at 90°C. The solid mixture obtained by cooling at room temperature was heated to 120℃.
The mixture was heated to melt once, immediately cast into a 2 mm thick sheet, maintained at 120°C for 15 minutes, and then cooled to room temperature to obtain a rubber-like elastic sheet. When these sheets were immersed in toluene, they all formed a gel, and even when heated again to 130°C, they did not melt at all. That is, the above-mentioned polymer has both hot-melt properties and vulcanization reactivity. 【table】

Claims (1)

[Claims] 1 2,3-dichlorobutadiene-1,3 is 55~
100 parts by weight of a monomer mixture consisting of 90% by weight and 45 to 10% by weight of chloroprene under normal pressure in the presence of 1 to 20 parts by weight of a halogenated hydrocarbon having at least one bromine atom in the molecule. 20 organic solvents selected from aromatic hydrocarbons, aliphatic halogenated hydrocarbons, and cyclic ethers with a boiling point of 150°C or less
A method for producing a low molecular weight copolymer of 2,3-dichlorobutadiene-1,3 and chloroprene, which comprises copolymerizing in ~400 parts by weight.