JP2002173507A - Method for modifying chloroprene copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing and modifying a new modified chloroprene copolymer for producing carboxy group in a copolymer by hydrolyzing carboxylic anhydride unit in the copolymer consisting mainly of chloroprene monomer unit and an unsaturated carboxylic anhydride monomer unit. SOLUTION: This method for producing the modified chloroprene copolymer containing carboxy group is provided by hydrolyzing carboxylic anhydride unit in the copolymer consisting mainly of 2-chloro-1,3-butadiene monomer unit and the unsaturated carboxylic anhydride monomer unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to 2-chloro-1,2-chloro-1,
The present invention relates to a method for modifying a copolymer containing 3-butadiene monomer (hereinafter often abbreviated as chloroprene monomer) unit and unsaturated carboxylic anhydride monomer unit as main components. The present invention relates to a method for producing a modified chloroprene copolymer in which a carboxylic anhydride unit in a coalesced is modified into a carboxyl group by a hydrolysis reaction, and a modification method thereof.

[0002]

2. Description of the Related Art Chloroprene polymers have good characteristics such as mechanical strength, weather resistance, heat resistance and chemical resistance.
It is used in a wide range of fields such as general industrial rubber products, automobile parts, adhesives, and various industrial parts. In particular, adhesives, which utilize the high crystallinity of the chloroprene polymer, are widely used as contact glues or graft glues. However, in recent years, the performance of adhesives has been improved, and the required characteristics relating to adhesive performance have become higher. Accordingly, further improvement of the chloroprene polymer is desired.

[0003] Means for improving the properties of chloroprene polymers have conventionally been achieved by changing the composition ratio of the microstructure of the polymer by changing the polymerization temperature, by changing the polymer structure using a comonomer, or by changing the chain transfer agent. Changes in polymer terminal structures are known, and there are many cases (Rubber Chemistry and Te
chemistry, 49 , 670 (1976)). Examples of the comonomer include sulfur, 2,3-dichloro-
1,3-Butadiene, 1-chloro-1,3-butadiene, styrene, acrylonitrile, isoprene, butadiene, acrylic acid or methacrylic acid, and esters thereof are known. Above all, copolymerization of a chloroprene monomer with a methacrylic acid monomer or an acrylic acid monomer results in a copolymer having a carboxyl group in the molecule, which is useful as an adhesive. However, methacrylic acid monomers and acrylic acid monomers are less reactive than chloroprene monomers and thus are less likely to be incorporated into the molecule, making it difficult to obtain a copolymer having a high carboxyl group content. Naturally, there were limits to improving the properties.

On the other hand, it has recently been found that a chloroprene monomer and a maleic anhydride monomer, which is a kind of unsaturated carboxylic anhydride, are significantly copolymerized (J. Polym. Sci. , Polym.
m. , 32 , 2301 (1994);
No. 839). However, the acid anhydride group is inferior in reactivity to the carboxyl group and is unsuitable for use in which the reaction is completed in a short time or cannot be performed at a high temperature. It preferably contains a carboxyl group rather than an anhydride group.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a method for hydrolyzing carboxylic anhydride units in a copolymer containing chloroprene monomer units and unsaturated carboxylic anhydride monomer units as main components. The present invention provides a method for producing a novel modified chloroprene copolymer, which produces a carboxyl group in the copolymer, and a modification method.

[0006]

Means for Solving the Problems The present inventors have proposed that a carboxylic anhydride unit in a copolymer containing a chloroprene monomer unit and an unsaturated carboxylic anhydride monomer unit as main components is converted to a carboxylic acid group. As a result of studying the method of denaturation,
The present inventors have found that a carboxyl group can be efficiently generated in a copolymer by mixing or dispersing water in the copolymer solution, and arrived at the present invention. That is, in the present invention, a carboxylic anhydride unit in a copolymer containing 2-chloro-1,3-butadiene monomer units and unsaturated carboxylic anhydride monomer units as main components is subjected to a hydrolysis reaction. A method for producing a modified chloroprene copolymer containing a carboxyl group, characterized by comprising: Further, the present invention
Dissolving a copolymer mainly comprising -chloro-1,3-butadiene monomer unit and unsaturated carboxylic anhydride monomer unit in an organic solvent capable of dissolving the copolymer; A method for modifying a chloroprene copolymer characterized by mixing or dispersing water in a solution to cause a carboxylic anhydride unit in the copolymer to undergo a hydrolysis reaction to generate a carboxyl group in the copolymer. .

Hereinafter, the present invention will be described in detail. The copolymer having a chloroprene monomer unit and an unsaturated carboxylic anhydride monomer unit as main components used in the present invention comprises a chloroprene monomer and an unsaturated carboxylic acid represented by the following general formula (1). At least one of the anhydrides can be produced by a known chloroprene polymerization method in which monomers are polymerized in the form of an emulsion, a solution, a suspension, or a bulk using a radical initiator.

[0008]

Embedded image

Here, R ¹ and R ² are hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different. Specific examples of the compound include maleic anhydride and citraconic anhydride. The content ratio of the unsaturated carboxylic acid anhydride monomer unit contained in the copolymer is practically selected in the range of 0.1 to 50 mol%.

[0010] Further, the copolymer containing chloroprene monomer units and unsaturated carboxylic anhydride monomer units as main components used in the present invention may contain, if necessary, a monomer copolymerizable therewith. Is used. One example is 1
-Chloro-1,3-butadiene, 2,3-dichloro-
Conjugated diene monomers such as 1,3-butadiene, butadiene, isoprene, 2-fluoro-1,3-butadiene, 2-bromo-1,3-butadiene, 2-cyano-1,3-butadiene, acrylonitrile, styrene And styrene derivatives, acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, aminomethyl acrylate, aminoethyl acrylate, aminopropyl acrylate, dimethylaminomethyl acrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminomethyl acrylate,
Acrylic esters such as diethylaminoethyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, propyl methacrylate, aminomethyl methacrylate, aminoethyl methacrylate, aminopropyl methacrylate, dimethylaminomethyl methacrylate, dimethylaminoethyl methacrylate, dimethylaminopropyl methacrylate, diethylaminomethyl Methacrylates such as methacrylate and diethylaminoethyl methacrylate; furthermore, maleimide, N-phenylmaleimide, N- (2-chlorophenyl) maleimide, N-cyclohexylmaleimide, N-
Examples include vinyl monomers such as lauryl maleimide and sulfur.

As a solvent when the copolymer is produced by a solution polymerization method, any solvent can be used without limitation as long as it can dissolve the unsaturated carboxylic acid anhydride monomer. For example, methyl ethyl ketone, Methyl isobutyl ketone, acetone, tetrahydrofuran, dimethyl sulfoxide,
And dimethylformamide. The amount of the organic solvent charged is 80% by mass or less, preferably 50% by mass or less, and more preferably 40% by mass or less, from the viewpoint of productivity, as mass% of the organic solvent with respect to the sum of all monomers and the organic solvent used. It is as follows. In particular, when a high molecular weight is desired, the content is preferably set to 50% by mass or less.

The charge ratio of the chloroprene monomer and the unsaturated carboxylic anhydride monomer can be freely selected depending on the desired copolymer composition. From the viewpoint of improving the characteristics of the chloroprene-based polymer, the molar ratio of the chloroprene monomer to the unsaturated carboxylic anhydride monomer is 1: 3 to 100000:
1, preferably in the range of 1: 1 to 1000: 1 is practically selected.

[0013] The polymerization temperature is in the range of -20 to 100 ° C, preferably 10 to 55 ° C, more preferably 30 to 5 ° C.
It is in the range of 0 ° C. If the temperature is lower than −20 ° C., the reaction rate becomes extremely slow, which is industrially disadvantageous.

The polymerization initiator is not particularly limited as long as it generates free radicals at the polymerization temperature. For example, 2,2'-azobis (4-methoxy-2,4
-Dimethylvaleronitrile), azo compounds such as 2,2'-azobisisobutyronitrile, and organic peroxides such as di-n-propylperoxydicarbonate and lauroyl peroxide.

The conversion of the monomer can be selected under any conditions except for the very early stage after the start of the reaction. In consideration of productivity, 50% by mass or more is recommended. When a predetermined conversion is reached, the reaction solution is cooled and the reaction is stopped by adding an appropriate amount of a polymerization inhibitor. As the polymerization inhibitor, well-known radical polymerization inhibitors such as thiodiphenylamine and 4-tert-butylcatechol are used.

The molecular weight of the copolymer is selected according to the application, but in order to exhibit the characteristics of the chloroprene polymer,
It is practically preferable that the number average molecular weight Mn is 100,000 or more. The molecular weight of the copolymer can be adjusted by adding a chain transfer agent. The type of the chain transfer agent is not particularly limited. For example, n-dodecyl mercaptan, t
Alkyl mercaptans such as tert-dodecyl mercaptan and octyl mercaptan, xanthogen disulfides such as diethyl xanthogen disulfide and diisopropyl xanthogen disulfide, and halogen compounds such as iodoform are used.

By employing the above-described operations and conditions, a copolymer containing chloroprene monomer units and unsaturated carboxylic anhydride monomer units as main components can be obtained.

The most important point of the present invention is a method for modifying the above chloroprene copolymer into a carboxyl group-containing copolymer. Hereinafter, the modification method will be described in detail.

A solution prepared by dissolving the copolymer in an organic solvent is prepared. Examples of the organic solvent used include toluene, benzene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dimethyl sulfoxide, and dimethylformamide. This solution may be prepared by dissolving the copolymer in an organic solvent, or may be used as it is as a polymerization reaction end solution. A predetermined amount of water is added to this solution and mixed or dispersed. The amount of water to be added varies depending on the desired amount of modification with a carboxyl group. However, when all of the carboxylic anhydride units in the copolymer are modified into carboxyl groups, a substantial amount of carboxylic anhydride units or more is required. Becomes Practically, the molar amount is preferably 1.5 times or more. The content of carboxylic anhydride monomer units in the copolymer containing chloroprene monomer units and unsaturated carboxylic anhydride monomer units as main components is preferably 0.1 mol% or more. It is preferable in terms of improving the characteristics of the coalescence, and more preferably 0.5 mol% or more and 50 mol% or less.

As a method for bringing the carboxylic acid anhydride unit in the copolymer dissolved in the organic solvent into contact with water, generally known unit operations relating to mixing and stirring of chemical engineering can be employed. For example, a method of mixing and dispersing water by placing the solution and water in a closed container and shaking or shaking operation, a method of mixing the solution by dropping water while stirring and putting the solution in a closed mixer, For example, there is a method in which water is injected together with an inert gas from a nozzle tip in a state of being immersed in a solution, which is placed in a closed reaction vessel and placed in advance in a solution.

The temperature at which the carboxylic anhydride units in the copolymer are hydrolyzed by mixing or dispersing water in the copolymer solution is 20 ° C. or higher, preferably 40 ° C. or higher, more preferably 50 ° C. That is all. The reaction time may be set so that the above-mentioned denaturation reaction is sufficiently achieved. For example, the reaction time is 10 minutes to 24 hours at 40 ° C. and 2 hours at 50 ° C.
Minutes to 4 hours.

The chloroprene copolymer modified by the method of the present invention contains a large amount of carboxyl groups which could not be achieved conventionally, and is suitable for applications utilizing the properties and reactivity of carboxyl groups. In addition, as long as the properties of the chloroprene copolymer obtained by the present invention are not impaired, commonly used additives and auxiliaries can be appropriately added. Suitable additives and auxiliaries include antioxidants, lubricants, plasticizers, resins, UV absorbers, stabilizers, pigments, colorants, fillers and the like. In addition, the concentration can be appropriately adjusted by removing the solvent or adding the solvent later.

[0023]

EXAMPLES The present invention will be described in detail with reference to the following examples, but the present invention is not limited to the following examples. In the following description, parts and% unless otherwise specified
Indicates on a mass basis.

The average molecular weight was measured by GPC (gel permeation chromatography, standard polystyrene conversion). The column used for the measurement is PLgel 10 μm MIXED-B (Poly (styrene / divinylbenzene) having a particle size of 8 to 10 μm) manufactured by Polymer Laboratory Co., Ltd., and the column oven is Shi, manufactured by Shimadzu Corporation.
Madzu CTO-6A, detector is RID-6A. The solvent used was tetrahydrofuran, and the column temperature was 35
The measurement was performed under the conditions of ° C and a flow rate of 1 ml / min. The measurement of the total chlorine amount was performed according to JIS K7229. Fourier transform infrared absorption spectrum is obtained by applying a methyl ethyl ketone solution of a copolymer to a KRS plate, drying the solution,
N ELMER FT-IR SPECTRUM200
It measured using 0.

Example 1 1) Production of chloroprene monomer-maleic anhydride copolymer Using a 1-liter pressure-resistant glass reactor equipped with a SUS pipe and a valve, the following conditions were applied while dry nitrogen gas was passed. Was performed. In a reactor adjusted to an internal temperature of 15 ° C., 166 g of maleic anhydride was added while stirring 130 g of methyl ethyl ketone (MEK) dehydrated to a water content of 20 ppm. After the maleic anhydride monomer was completely dissolved, 149 g of chloroprene monomer and 1-chloro-
1 g of 1,3-butadiene monomer was added. When the internal temperature was raised to 40 ° C., a solution in which 0.2 g of an initiator (2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile)) was dissolved in 6 g of MEK in advance was added. did. After a lapse of 24 hours, the reaction solution was cooled, thiodiphenylamine was added, and 30 ppm was added to the total amount of the monomers to stop the reaction, thereby obtaining a copolymer.

The copolymer was purified using MEK and heptane. The number average molecular weight Mn determined by GPC is 12.5
It was 10,000. The total chlorine content of the copolymer was 25% by mass.

2) Modification of chloroprene monomer-maleic anhydride copolymer 30 g of the above copolymer was dissolved in 30 g of MEK by stirring in a 100 ml glass reactor under a nitrogen atmosphere, and purified water was added. 4.2 g (corresponding to twice the molar amount of maleic anhydride units) were added. After reacting at an internal temperature of 60 ° C. for 30 minutes, it was cooled.

FIG. 1 shows the Fourier transform infrared absorption spectrum of the modified copolymer.

Example 2 In Example 1, the reaction conditions between the copolymer and pure water were changed to 40.
C. for 1 hour. FIG. 2 shows the Fourier transform infrared absorption spectrum of the modified copolymer.

Comparative Example 1 The Fourier transform infrared absorption spectrum of the copolymer before modification described in Examples 1 and 2 is shown in FIG.

In the Fourier transform infrared absorption spectra shown in FIGS. 1 to 3, 1780 cm ^-1 and 18 shown in FIG.
The absorption around 50 cm ^-1 is due to the carbonyl of the carboxylic anhydride unit in the copolymer. 1 and 2
The absorption near 1710 cm ^-1 appearing in the above is due to the carbonyl of the carboxyl group generated by the hydrolysis reaction. Incidentally, the FIG. 1 and FIG. 2, the absorption around 1780 cm ^-1 and 1850 cm ^-1 appearing in FIG. 3 is hardly detected, a carboxylic acid anhydride units in the copolymer are hardly modified Is shown.

From the comparison between the examples and the comparative examples, according to the method of the present invention, the carboxylic anhydride in the copolymer containing chloroprene monomer units and unsaturated carboxylic anhydride monomer units as main components was obtained. It is clear that the units are efficiently modified to carboxyl groups.

[0033]

According to the method of the present invention, carboxylic anhydride units in a copolymer containing chloroprene monomer units and unsaturated carboxylic anhydride monomers as main components can be efficiently converted into carboxyl groups. Can be denatured. The copolymer thus obtained is
Compared to a conventionally known chloroprene copolymer, the copolymer has more carboxyl groups in the molecule and can be expected to have excellent properties derived from the carboxyl group, and can be expected to be put to practical use and industrialized.

[Brief description of the drawings]

FIG. 1 is a Fourier transform infrared absorption spectrum of the modified copolymer obtained in Example 1.

FIG. 2 is a Fourier transform infrared absorption spectrum of the modified copolymer obtained in Example 2.

FIG. 3 is a Fourier transform infrared absorption spectrum of a copolymer before being modified by the method of the present invention described in Comparative Example 1.

Claims (6)

[Claims] 1. A carboxylic anhydride unit in a copolymer containing 2-chloro-1,3-butadiene monomer units and unsaturated carboxylic acid anhydride monomer units as main components, by a hydrolysis reaction. A method for producing a modified chloroprene copolymer containing a carboxyl group. 2. The copolymer having a 2-chloro-1,3-butadiene monomer unit and an unsaturated carboxylic acid anhydride monomer unit as main components has a carboxylic acid anhydride monomer unit content of at least 2%. The method for producing a modified chloroprene copolymer according to claim 1, wherein the amount is 0.1 mol% or more. 3. A copolymer having a 2-chloro-1,3-butadiene monomer unit and an unsaturated carboxylic anhydride monomer unit as main components has a number average molecular weight (Mn) of 100,000 or more. The method for producing a modified chloroprene copolymer according to claim 1, wherein: 4. A copolymer comprising a 2-chloro-1,3-butadiene monomer unit and an unsaturated carboxylic acid anhydride monomer unit as a main component is a 1-chloro-1,3-butadiene monomer. 2. The method for producing a modified chloroprene copolymer according to claim 1, wherein the modified chloroprene copolymer contains units and / or 2,3-dichloro-1,3-butadiene monomer units. 5. A carboxylic acid anhydride unit in a copolymer containing a 2-chloro-1,3-butadiene monomer unit and an unsaturated carboxylic acid anhydride monomer unit as main components in the presence of water. A method for modifying a chloroprene copolymer, comprising producing a carboxyl group in the copolymer by a hydrolysis reaction. 6. The method for modifying a chloroprene copolymer according to claim 5, wherein the reaction temperature is 20 ° C. or higher.