CN101503490B - A kind of synthetic method of low molecular weight styrene/maleic anhydride alternating copolymer - Google Patents

Abstract

The invention discloses a method for synthesizing low-molecular-weight styrene/maleic anhydride alternating copolymers, belonging to the field of polymer precipitation polymerization. Both the medium and the chain transfer agent used in the existing method for preparing styrene/maleic anhydride copolymer by precipitation polymerization have disadvantages. In the present invention, the mixed solvent of organic acid alkyl ester and alkane is used as the precipitation polymerization reaction medium, α-methylstyrene or vinyl acetate is used as the molecular weight regulator, and organic peroxide or azo compound is used as the initiator to initiate the single polymerization reaction. Bulk styrene and styrene are copolymerized to produce low molecular weight styrene/maleic anhydride alternating copolymers. The invention has the advantages of simple process, good performance of the synthesized copolymer, economy and environmental protection.

Description

A kind of synthetic method of low molecular weight styrene/maleic anhydride alternating copolymer

technical field

The invention belongs to the field of polymer precipitation polymerization, in particular to a method for preparing low molecular weight styrene/maleic anhydride alternating copolymers by precipitation polymerization.

Background technique

Low-molecular-weight styrene/maleic anhydride alternating copolymer is a polymer with a wide range of uses. It can be used as paper surface sizing agent, organic pigment dispersant, and emulsion polymerization in papermaking, textile, printing and dyeing, coating, chemical and other industries. protective colloid etc.

At present, the preparation methods of styrene/maleic anhydride copolymer mainly include solution polymerization, a small amount of bulk polymerization, bulk-suspension polymerization, and precipitation polymerization. Among them, compared with other polymerization methods, precipitation polymerization has the advantages of simple post-treatment process and low cost.

For example, Zhang Guoyun used benzoyl peroxide (BPO) as the trigger in the article "Preparation and Application of SMA Surface Sizing Agent" ("Paper Chemicals", 2005, 17(3), pp.30-32). agent, toluene as solvent, synthesized styrene/maleic anhydride random copolymer by precipitation polymerization. Wang Rongwei, Yu Jianyi, etc. chose the precipitation polymerization method in the article "Synthesis of Low Molecular Weight SMA Alternating Copolymer" ("Petrochemical Industry", 1994, 23, pp.706-410), using dodecyl mercaptan as the chain transfer agent, A low molecular weight styrene/maleic anhydride alternating copolymer was prepared with toluene as solvent.

However, the currently reported precipitation polymerization generally uses the toxic solvent toluene as the reaction medium, which is not conducive to environmental protection. In addition, the use of mercaptan chain transfer agents causes the prepared copolymer to have a pungent odor, which affects the performance of the copolymer.

Contents of the invention

The purpose of the present invention is to solve the problems of the prior art, and provide a kind of environmental protection, the precipitation polymerization method of the low molecular weight styrene/maleic anhydride alternating copolymer without irritating odor.

The synthetic method of low molecular weight styrene/maleic anhydride alternating copolymer provided by the present invention may further comprise the steps:

Under the condition of nitrogen protection and stirring, monomer maleic anhydride (MAH) and initiator are added to the medium to dissolve, and when heated to 60-80 °C, monomer styrene (St) and molecular weight regulator are added dropwise, After the dropwise addition, continue to stir and react for 1 to 8 hours to obtain a dispersion system of low molecular weight styrene/maleic anhydride polymer particles, centrifuge and dry the dispersion system to obtain a low molecular weight styrene/maleic anhydride alternating copolymer;

Wherein, the initiator is an organic peroxide or an azo compound; the medium is a mixed solution of an organic acid alkyl ester and alkane or cyclohexane; the molecular weight regulator is α-methylstyrene (AMS) or vinyl acetate (VAC);

The consumption relationship of maleic anhydride and styrene is 1: 0.90～0.96 by molar ratio; Two kinds of monomer styrene and horse The sum of the mass concentration of toic anhydride is 2.0～7.5%; the mass concentration of initiator in the reaction system is 0.05～0.35%; the mass concentration of molecular weight regulator in the reaction system is 0.10～0.45%; the organic acid alkyl ester and alkane The volume fraction of organic acid alkyl ester in the mixed solution is 20-80%.

Wherein, described initiator is conventional pyrolysis type initiator, has benzoyl peroxide (BPO), dicumyl peroxide, dicumyl peroxide for the well-known organic peroxide of those skilled in the art. tert-butyl, lauryl peroxide, tert-butyl peroxybenzoate, diisopropyl peroxydicarbonate or dicyclohexyl peroxydicarbonate, etc. Azo compounds include azobisisobutyronitrile (AIBN) or azobisisoheptanonitrile.

式中，R₁为H、C原子数为1～8的烷基，R₂为C原子数为1～5的烷基，具体可包括甲酸乙酯、甲酸丙酯、甲酸异丁酯、甲酸戊酯、乙酸乙酯、乙酸丁酯、乙酸异丁酯、乙酸仲丁酯、乙酸戊酯、乙酸异戊酯、乙酸苄酯、丙酸甲酯、丙酸乙酯、丙酸丁酯、丁酸甲酯、丁酸乙酯、丁酸丁酯、丁酸异戊酯、异戊酸乙酯、异戊酸异戊酯、苯甲酸甲酯、苯甲酸乙酯、苯甲酸丙酯、苯甲酸丁酯、苯甲酸异戊酯、苯乙酸甲酯或苯乙酸乙酯等。而考虑到介质应具有适度的极性、溶解度参数和粘度，有机酸烷基酯结构通式中，R₁优选C原子数为1～8的烷基。The structural general formula of described organic acid alkyl ester is:

In the formula, _R1 is H, an alkyl group with 1 to 8 C atoms, and _R2 is an alkyl group with 1 to 5 C atoms, which may specifically include ethyl formate, propyl formate, isobutyl formate, formic acid Amyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, amyl acetate, isoamyl acetate, benzyl acetate, methyl propionate, ethyl propionate, butyl propionate, butyl Methyl Butyrate, Ethyl Butyrate, Butyl Butyrate, Isoamyl Butyrate, Ethyl Isovalerate, Isoamyl Isovalerate, Methyl Benzoate, Ethyl Benzoate, Propyl Benzoate, Benzoic Acid Butyl, isopentyl benzoate, methyl phenylacetate or ethyl phenylacetate, etc. And considering that the medium should have moderate polarity, solubility parameter and viscosity, in the general formula of organic acid alkyl ester, R ₁ is preferably an alkyl group with 1 to 8 C atoms.

The alkane is n-hexane, n-heptane, n-pentane, n-octane or isooctane.

The number average molecular weight range of the low molecular weight styrene/maleic anhydride alternating copolymer is 3000-12000 g/mol, and the molecular weight distribution range is 1.36-2.0.

Can adopt water bath or oil bath heating reaction system among the present invention, according to known technology, polymerization reaction temperature is determined by the decomposition temperature of initiator, in order to reduce the molecular weight of copolymer, adopt as far as possible greater than the decomposition temperature of initiator, but lower than The reaction system is heated at the temperature of the boiling point of the solvent.

Key of the present invention is the selection of reaction medium, and selection principle is as follows: 1) medium has certain dissolving effect to two kinds of monomers MAH and St and initiator, is homogeneous system before guaranteeing reaction; 2) medium can not dissolve all The resulting low molecular weight styrene/maleic anhydride copolymer can be precipitated from the medium when the molecular chain of the copolymer reaches a certain critical length.

The present invention has the following beneficial effects:

1) The present invention uses a low-toxic solvent as the reaction medium. After the reaction is completed, the copolymer is precipitated from the medium in the form of particles without adding a precipitant. The post-treatment process is simple, and the solvent can be recycled.

2) The molecular weight regulator used in the present invention can effectively regulate the molecular weight of the copolymer while avoiding the influence of the mercaptan chain transfer agent on the properties of the copolymer.

Description of drawings

The gel permeation chromatography (GPC) spectrogram of the copolymer prepared in Fig. 1, embodiment 1.

The gel permeation chromatography (GPC) spectrogram of the copolymer prepared in Fig. 2, embodiment 3.

The gel permeation chromatography (GPC) spectrogram of the copolymer prepared in Fig. 3, embodiment 4.

The gel permeation chromatography (GPC) spectrogram of the copolymer prepared in Fig. 4, embodiment 7.

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Detailed ways

In the following examples, the number-average molecular weight and distribution of the prepared copolymers were measured by a liquid chromatograph with a model of waters 1515 and a specification of 300PSI/0.001-10ML/min/1-1.75RIV/1.

Example 1

Material preparation: monomer MAH 1.7658g, St 1.6892g, the molar ratio of the two is 1:0.90; initiator AIBN 0.1831g; solvent mixture of isoamyl acetate 9mL and cyclohexane 36mL; molecular weight regulator AMS 0.2132g .

Synthesis of copolymer: put MAH, AIBN and solvent in a four-neck flask equipped with a stirring device and nitrogen gas, stir at room temperature for 15 minutes, heat for 15 minutes in a constant temperature water bath at 80°C, and then drop them at a constant speed within 1 hour The mixture of St and AMS, after the dropwise addition, continue to stir and react for 1h to obtain a dispersion system of styrene/maleic anhydride alternating copolymer, centrifuge the dispersion and dry to obtain a white powder of styrene/maleic anhydride alternating copolymer .

The results of polymerization yield (C _p ), number average molecular weight (Mn) and distribution (PDI) of the copolymer are shown in Table 1, and the GPC spectrum of the copolymer is shown in Fig. 1 .

Example 2

Preparation: monomer MAH 0.4420g, St 0.557g, the molar ratio of the two is 1:0.90; initiator AIBN 0.0459g; solvent is a mixture of 9mL butyl acetate and 36mL cyclohexane; molecular weight regulator AMS 0.0542g .

Synthesis of copolymers: put MAH, AIBN and solvent in a four-neck flask with a stirring device and nitrogen gas, stir at room temperature for 15 minutes, heat for 15 minutes in a constant temperature water bath at 80°C, and then drop them at a constant speed within 0.5 hours Complete the mixture of St and AMS, continue to stir and react for 8 hours after the dropwise addition, and obtain the dispersion system of styrene/maleic anhydride alternating copolymer, centrifuge and dry the dispersion system to obtain the white color of styrene/maleic anhydride alternating copolymer powder.

The results of polymerization yield (C _p ), number average molecular weight (Mn) and distribution (PDI) of the copolymer are shown in Table 1.

Example 3

Material preparation: monomer MAH 1.3245g, St 1.2685g, the molar ratio of the two is 1:0.96; initiator AIBN 0.1360g; solvent mixture of isoamyl acetate 36mL and n-hexane 9mL; molecular weight regulator VAC 0.1175g.

Synthesis of copolymer: put MAH, AIBN and solvent in a four-neck flask with a stirring device and nitrogen gas, stir at room temperature for 15 minutes, heat in a constant temperature water bath at 60°C for 15 minutes, and then drop them at a constant speed within 1 hour The mixture of St and VAC, after the dropwise addition, continue to stir and react for 6 hours to obtain a dispersion system of styrene/maleic anhydride alternating copolymer, centrifuge the dispersion system and dry to obtain a white powder of styrene/maleic anhydride alternating copolymer .

The results of polymerization yield (C _p ), number average molecular weight (Mn) and distribution (PDI) of the copolymer are shown in Table 1, and the GPC spectrum of the copolymer is shown in Figure 2.

Example 4

Material preparation: monomer MAH 1.3240g, St 1.2664g, the molar ratio of the two is 1:0.9; initiator AIBN 0.1354g; solvent butyl acetate 9mL and n-hexane 36mL mixed solution; molecular weight regulator VAC 0.1168g.

Synthesis of copolymer: put MAH, AIBN and solvent in a four-neck flask with a stirring device and nitrogen gas, stir at room temperature for 15 minutes, heat for 15 minutes in a constant temperature water bath at 70°C, and then drop them at a constant speed within 1 hour The mixture of St and VAC, after the dropwise addition, continue to stir and react for 5 hours to obtain a dispersion system of styrene/maleic anhydride alternating copolymer, centrifuge the dispersion system and dry to obtain a white powder of styrene/maleic anhydride alternating copolymer .

The results of polymerization yield (C _p ), number average molecular weight (Mn) and distribution (PDI) of the copolymer are shown in Table 1, and the GPC spectrum of the copolymer is shown in Fig. 3 .

Example 5

Material preparation: monomer MAH 1.3239g, St 1.3501g, the molar ratio of the two is 1:0.96; initiator AIBN 0.0272g; solvent butyl acetate 9mL and cyclohexane 36mL mixed solution; molecular weight regulator AMS 0.0643g.

Synthesis of copolymer: put MAH, AIBN and solvent in a four-neck flask equipped with a stirring device and nitrogen gas, stir at room temperature for 15 minutes, heat for 15 minutes in a constant temperature water bath at 80°C, and then drop them at a constant speed within 1 hour The mixture of St and AMS, after the dropwise addition, continue to stir and react for 5 hours to obtain a dispersion system of styrene/maleic anhydride alternating copolymer, centrifuge the dispersion system and dry to obtain a white powder of styrene/maleic anhydride alternating copolymer .

The results of polymerization yield (C _p ), number average molecular weight (Mn) and distribution (PDI) of the copolymer are shown in Table 1, and the GPC spectrum of the copolymer is shown in Fig. 3 .

Example 6

Material preparation: monomer MAH 1.3244g, St 1.2673g, the molar ratio of the two is 1:0.9; initiator AIBN 0.1372g; solvent mixture of isoamyl acetate 22.5mL and cyclohexane 22.5mL; molecular weight regulator AMS 0.1603g.

Synthesis of copolymer: put MAH, AIBN and solvent in a four-neck flask equipped with a stirring device and nitrogen gas, stir at room temperature for 15 minutes, heat for 15 minutes in a constant temperature water bath at 80°C, and then drop them at a constant speed within 1 hour The mixture of St and AMS, after the dropwise addition, continue to stir and react for 5 hours to obtain a dispersion system of styrene/maleic anhydride alternating copolymer, centrifuge the dispersion system and dry to obtain a white powder of styrene/maleic anhydride alternating copolymer .

The results of polymerization yield (C _p ), number average molecular weight (Mn) and distribution (PDI) of the copolymer are shown in Table 1.

Example 7

Material preparation: monomer MAH 1.3246g, St 1.2668g, the molar ratio of the two is 1:0.9; initiator BPO 0.0826g; solvent mixture of ethyl butyrate 9mL and cyclohexane 36mL; molecular weight regulator AMS 0.1615g .

Synthesis of copolymer: put MAH, AIBN and solvent in a four-neck flask equipped with a stirring device and nitrogen gas, stir at room temperature for 15 minutes, heat for 15 minutes in a constant temperature water bath at 80°C, and then drop them at a constant speed within 1 hour The mixture of St and AMS, after the dropwise addition, continue to stir and react for 5 hours to obtain a dispersion system of styrene/maleic anhydride alternating copolymer, centrifuge the dispersion system and dry to obtain a white powder of styrene/maleic anhydride alternating copolymer .

The results of polymerization yield (C _p ), number average molecular weight (Mn) and distribution (PDI) of the copolymer are shown in Table 1, and the GPC spectrum of the copolymer is shown in Figure 4.

Example Number average molecular weight Mn/(g/mol) Molecular weight distribution PDI Polymerization yield C_p 1 4503 1.46 90.1% 2 3016 1.36 96.6% 3 7156 1.62 49.7% 4 6531 1.53 96.4% 5 11762 1.75 94.8% 6 4258 1.43 92.4% 7 7470 1.96 89.2%

The molecular weight, molecular weight distribution and polymerization yield of the low molecular weight styrene/maleic anhydride alternating copolymer prepared in the embodiment 1-7 of table 1

Claims (5)

1. the synthetic method of a low molecular weight phenylethylene/maleic anhydride alternate copolymer is characterized in that, may further comprise the steps:

Under nitrogen protection and stirring condition, monomer maleic anhydride MAH and initiator joined in the medium dissolve, and when being heated to 60～80 ℃, drip monomer styrene St and molecular weight regulator, dropwise the back and continue stirring reaction 1～8h, obtain the dispersion system of low molecular weight phenylethylene/maleic anhydride polymer particle,, obtain low molecular weight phenylethylene/maleic anhydride alternate copolymer dispersion system centrifugation, drying;

Wherein, described initiator is organo-peroxide or azo-compound; Described medium is the mixing solutions of organic acid alkyl ester and alkane or hexanaphthene; Described molecular weight regulator is alpha-methyl styrene AMS or vinyl-acetic ester VAC; The general structure of described organic acid alkyl ester is: In the formula, R ₁For H, C atomicity are 1～8 alkyl, R ₂It for the C atomicity 1～5 alkyl; Described alkane is normal hexane, normal heptane, Skellysolve A, octane or octane-iso;

Maleic anhydride and the cinnamic magnitude relation of using are 1: 0.90～0.96 in molar ratio; Two kinds of monomer maleic anhydrides and cinnamic mass concentration sum are 2.0～7.5% in the reaction system; The mass concentration of initiator is 0.05～0.35% in the reaction system; The mass concentration of molecular weight regulator is 0.10～0.45% in the reaction system; The volume fraction of organic acid alkyl ester is 20～80% in the mixing solutions of organic acid alkyl ester and alkane.

2. method according to claim 1, it is characterized in that described organo-peroxide is benzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, dilauroyl peroxide, the special butyl ester of peroxidation phenylformic acid, peroxy dicarbonate diisopropyl ester or di-cyclohexylperoxy dicarbonate.

3. method according to claim 1 is characterized in that, described azo-compound is Diisopropyl azodicarboxylate or 2,2'-Azobis(2,4-dimethylvaleronitrile).

4. method according to claim 1 is characterized in that, R in the general structure of described organic acid alkyl ester ₁Be selected from the C atomicity and be 1～8 alkyl.

5. method according to claim 1 is characterized in that, the number-average molecular weight scope of described low molecular weight phenylethylene/maleic anhydride alternate copolymer is 3000～12000g/mol, and range of molecular weight distributions is 1.36～2.0.

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