阅读说明：本技术 一种丁基橡胶/聚乳酸接枝聚合物的制备方法 (Preparation method of butyl rubber/polylactic acid graft polymer ) 是由 贾翔宇 任纪文 张学琪 翟路路 付翁 孙清 李付姣 文川 叶媛园 张阳 于 2020-11-25 设计创作，主要内容包括：本发明涉及一种丁基橡胶/聚乳酸接枝聚合物的制备方法,属于改性聚乳酸技术领域。包括以下步骤：a、配制丁基橡胶溶液；b、将环氧化试剂加入到丁基橡胶溶液中,生成环氧化丁基橡胶；c、将环氧化丁基橡胶配制成环氧化丁基橡胶溶液,加入酸性开环试剂,生成羟基化丁基橡胶；d、将羟基化丁基橡胶配制成羟基化丁基橡胶溶液,在惰性气氛保护下,加入丙交酯和聚合催化剂,生成丁基橡胶和聚乳酸的接枝共聚物。本发明制得的丁基橡胶接枝聚乳酸的大分子接枝聚合物,丁基橡胶主链具有良好的热稳定性和链柔顺性,改善了聚乳酸的韧性和加工性能,这种具有热塑性的接枝聚合物有望在食品保鲜膜、3D打印材料等领域有广泛应用。(The invention relates to a preparation method of a butyl rubber/polylactic acid graft polymer, belonging to the technical field of modified polylactic acid. The method comprises the following steps: a. preparing a butyl rubber solution; b. adding an epoxidizing agent into the butyl rubber solution to generate epoxidized butyl rubber; c. preparing epoxidized butyl rubber into an epoxidized butyl rubber solution, and adding an acidic ring-opening reagent to generate hydroxylated butyl rubber; d. preparing hydroxylated butyl rubber into a hydroxylated butyl rubber solution, and adding lactide and a polymerization catalyst under the protection of inert atmosphere to generate a graft copolymer of butyl rubber and polylactic acid. The macromolecular graft polymer of the butyl rubber grafted polylactic acid prepared by the invention has good thermal stability and chain flexibility of a butyl rubber main chain, improves the toughness and the processing performance of the polylactic acid, and is expected to be widely applied in the fields of food preservative films, 3D printing materials and the like.)

1. A preparation method of a butyl rubber/polylactic acid graft copolymer comprises the following steps:

a. preparing butyl rubber solution with the unsaturation degree of 0.5-3% and the number average molecular weight of 500-1000000, wherein the concentration is 10-100 g/L;

b. adding an epoxidizing agent into the butyl rubber solution, and controlling reaction conditions to generate epoxidizing butyl rubber; in the step, the molar ratio of the peroxide unit of the epoxidation reagent to the isoprene unit in the butyl rubber is (1-10): 1; the reaction temperature is controlled to be 0-80 ℃, the reaction time is controlled to be 0.5-12 h, and the epoxy group content of the obtained epoxidized butyl rubber is 0.5-3%;

c. preparing the epoxidized butyl rubber into an epoxidized butyl rubber solution, adding an acidic ring-opening reagent, and controlling reaction conditions to generate hydroxylated butyl rubber; in the step, the molar ratio of hydrogen ions of the acidic ring-opening reagent to epoxy groups in the epoxidized butyl rubber is (1-100): 1; the reaction temperature is controlled to be 0-80 ℃, and the reaction time is controlled to be 0.5-12 h;

d. preparing the hydroxylated butyl rubber into a hydroxylated butyl rubber solution, adding lactide and a polymerization catalyst under the protection of inert atmosphere, and controlling reaction conditions to generate a graft copolymer of the butyl rubber and polylactic acid; in the step, the molar ratio of the lactide to the hydroxyl groups of the hydroxylated butyl rubber is (1-100): 1; the molar ratio of the polymerization catalyst to the hydroxyl groups of the hydroxylated butyl rubber is (1-10): 1; the polymerization temperature is controlled to be 50-120 ℃, and the polymerization time is controlled to be 1-12 h.

2. The method for preparing a butyl rubber/polylactic acid graft copolymer as claimed in claim 1, wherein: the epoxidizing agent is a water-soluble organic acid system of peroxide or a water-insoluble system of organic acid.

3. The method for preparing a butyl rubber/polylactic acid graft copolymer as claimed in claim 2, wherein: when the epoxidation reagent is a water-soluble organic acid system of peroxide, the peroxide is selected from one of peroxycarboxylic acid, tert-butyl peroxide and hydrogen peroxide, and the water-soluble organic acid is selected from carboxylic acid of C1-C5.

4. The method for preparing a butyl rubber/polylactic acid graft copolymer as claimed in claim 2, wherein: when the epoxidation reagent is a water-insoluble system of an organic acid, the organic acid is selected from one of m-chloroperoxybenzoic acid, monoperoxyphthalic acid, peroxyformic acid, peroxyacetic acid, and trifluoroperoxyacetic acid.

5. The method for preparing a butyl rubber/polylactic acid graft copolymer as claimed in claim 1, wherein: in the step a, a solvent for preparing the butyl rubber solution is selected from one or a mixture of C5-C8 alkane, raffinate oil, cyclohexane, benzene, toluene, xylene, dichloromethane, chloroform, chlorobenzene, dichlorobenzene and tetrahydrofuran.

6. The method for preparing a butyl rubber/polylactic acid graft copolymer as claimed in claim 1, wherein: in the step C, a solvent for preparing the epoxidized butyl rubber solution is selected from one or a mixture of C5-C8 alkane, raffinate oil, cyclohexane, benzene, toluene, xylene, dichloromethane, chloroform, chlorobenzene, dichlorobenzene and tetrahydrofuran.

7. The method for preparing a butyl rubber/polylactic acid graft copolymer as claimed in claim 1, wherein: in the step d, a solvent for preparing the hydroxylated butyl rubber solution is selected from one or a mixture of C5-C8 alkane, raffinate oil, cyclohexane, benzene, toluene, xylene, dichloromethane, chloroform, chlorobenzene, dichlorobenzene and tetrahydrofuran.

8. The method for preparing a butyl rubber/polylactic acid graft copolymer as claimed in claim 1, wherein: the polymerization catalyst is selected from stannous octoate, stannic chloride, tetraphenyltin, boron trichloride, 4-dimethylaminopyridine and 4-pyrrolidinylpyridine.

9. The method for preparing a butyl rubber/polylactic acid graft copolymer as claimed in claim 1, wherein: the lactide is selected from D-lactide, L-lactide or their combination.

10. The method for preparing a butyl rubber/polylactic acid graft copolymer as claimed in claim 1, wherein: in the step c, the conversion rate of converting epoxy groups into hydroxyl groups is 50-100%.

Technical Field

The invention relates to a preparation method of modified polylactic acid, in particular to a preparation method of a butyl rubber/polylactic acid graft polymer, belonging to the technical field of modified polylactic acid.

Background

The polylactic acid is a novel degradable biological material, has higher strength and good biocompatibility, can be processed and formed by methods such as blow molding, injection molding and the like, and is simple and convenient to process. However, the disadvantages of brittle polylactic acid, poor toughness and low heat distortion temperature limit the application of polylactic acid in many fields.

The Chinese patent application with the application number of CN 201910831884.8 discloses a preparation method of linear-like comb-shaped fluorescent polylactic acid, which comprises the steps of firstly preparing linear liquid polybutadiene by utilizing active anion reaction, then synthesizing linear comb-shaped polylactic acid by ring-opening polymerization reaction, and then grafting the linear comb-shaped polylactic acid and fluorescent micromolecules by adopting esterification dehydration condensation reaction; in this application, linear liquid polybutadiene is used as an initiator for synthesizing linear comb-shaped polylactic acid by ring-opening polymerization. Also, the graft polymer has poor thermal stability.

The Chinese patent application with the application number of CN201910351882.9 discloses a preparation method of 1, 2-polybutadiene rubber toughening modified polylactic acid. Dissolving 1, 2-polybutadiene with different epoxy degrees into a lactide polymerization system, and controlling copolymerization reaction conditions to generate 1, 2-polybutadiene graft-modified polylactic acid; then the polylactic acid grafted and modified by the 1, 2-polybutadiene, the conventional 1, 2-polybutadiene and the polylactic acid are banburied to prepare the polylactic acid toughened and modified by the 1, 2-polybutadiene. Also, the polylactic acid toughened and modified by 1, 2-polybutadiene has the defect of poor thermal stability.

Disclosure of Invention

The present invention is to solve the above problems, and therefore provides a method for preparing a butyl rubber/polylactic acid graft polymer. According to the method, rubber molecules and lactide are subjected to graft copolymerization to generate the butyl rubber/polylactic acid graft polymer, so that the technical defects that the conventional polylactic acid is easy to brittle fracture during stretching and is difficult to form a polylactic acid film are effectively overcome; the butyl rubber/polylactic acid graft polymer prepared by the method also has good thermal stability.

The technical scheme for solving the problems is as follows:

a preparation method of a butyl rubber/polylactic acid graft copolymer comprises the following steps:

a. preparing butyl rubber solution with the unsaturation degree of 0.5-3% and the number average molecular weight of 500-1000000, wherein the concentration is 10-100 g/L;

b. adding an epoxidizing agent into the butyl rubber solution, and controlling reaction conditions to generate epoxidizing butyl rubber; in the step, the molar ratio of the peroxide unit of the epoxidation reagent to the isoprene unit in the butyl rubber is (1-10): 1; the reaction temperature is controlled to be 0-80 ℃, the reaction time is controlled to be 0.5-12 h, and the epoxy group content of the obtained epoxidized butyl rubber is 0.5-3%;

c. preparing the epoxidized butyl rubber into an epoxidized butyl rubber solution, adding an acidic ring-opening reagent, and controlling reaction conditions to generate hydroxylated butyl rubber; in the step, the molar ratio of hydrogen ions of the acidic ring-opening reagent to epoxy groups in the epoxidized butyl rubber is (1-100): 1; the reaction temperature is controlled to be 0-80 ℃, and the reaction time is controlled to be 0.5-12 h;

d. preparing the hydroxylated butyl rubber into a hydroxylated butyl rubber solution, adding lactide and a polymerization catalyst under the protection of inert atmosphere, and controlling reaction conditions to generate a graft copolymer of the butyl rubber and polylactic acid; in the step, the molar ratio of the lactide to the hydroxyl groups of the hydroxylated butyl rubber is (1-100): 1; the molar ratio of the polymerization catalyst to the hydroxyl groups of the hydroxylated butyl rubber is (1-10): 1; the polymerization temperature is controlled to be 50-120 ℃, and the polymerization time is controlled to be 1-12 h.

In the technical scheme of the invention, aiming at unsaturated double bonds on a butyl rubber molecular chain, firstly, the unsaturated double bonds are epoxidized by an epoxidation reagent to obtain epoxidized butyl rubber; then, hydroxylating an epoxy group by an acidic ring-opening reagent, and introducing hydroxyl into a side chain of the butyl rubber to obtain hydroxylated butyl rubber; and finally, mixing the hydroxylated butyl rubber with a lactide polymerization system, and carrying out copolymerization reaction to obtain the graft copolymer of the butyl rubber and the polylactic acid. The graft copolymer obtained by the method effectively solves the technical defects that the existing polylactic acid is easy to generate brittle fracture during stretching and is difficult to form a polylactic acid film; also has good thermal stability.

Preferably, the epoxidizing agent is a water-soluble organic acid system of a peroxide or a water-insoluble system of an organic acid.

In the above aspect, when the epoxidizing agent is a water-soluble organic acid system of peroxide, the peroxide is selected from one of peroxycarboxylic acid, tert-butyl peroxide and hydrogen peroxide, and the water-soluble organic acid is selected from carboxylic acids of C1 to C5.

In the above aspect, when the epoxidation reagent is a water-insoluble system of an organic acid, the organic acid is preferably one selected from m-chloroperoxybenzoic acid, monoperoxyphthalic acid, peroxyformic acid, peroxyacetic acid, and trifluoroperoxyacetic acid.

Preferably, in the step a, the solvent for preparing the butyl rubber solution is one or a mixture of C5-C8 alkane, raffinate oil, cyclohexane, benzene, toluene, xylene, dichloromethane, chloroform, chlorobenzene, dichlorobenzene and tetrahydrofuran.

Preferably, in the step C, the solvent for preparing the epoxidized butyl rubber solution is one or a mixture of C5-C8 alkane, raffinate oil, cyclohexane, benzene, toluene, xylene, dichloromethane, chloroform, chlorobenzene, dichlorobenzene and tetrahydrofuran.

Preferably, in the step d, the solvent for preparing the hydroxylated butyl rubber solution is one or a mixture of C5-C8 alkane, raffinate oil, cyclohexane, benzene, toluene, xylene, dichloromethane, chloroform, chlorobenzene, dichlorobenzene and tetrahydrofuran.

Preferably, the polymerization catalyst is selected from stannous octoate, stannic chloride, tetraphenylstannum, boron trichloride, 4-dimethylaminopyridine and 4-pyrrolidinylpyridine.

Preferably, the lactide is one or two selected from D-lactide and L-lactide.

Preferably, in the step c, the conversion rate of converting epoxy groups into hydroxyl groups is 50-100%.

In conclusion, the invention has the following beneficial effects:

according to the invention, hydroxyl is introduced into a butyl rubber side chain and then mixed with a lactide polymerization system, and lactide ring-opening polymerization or L (D) lactic acid polymerization is carried out on hydroxyl to obtain the macromolecular graft polymer of the butyl rubber grafted polylactic acid, wherein the butyl rubber main chain has good thermal stability and chain flexibility, so that the toughness and the processing performance of the polylactic acid are improved, and the graft polymer with thermoplasticity is expected to be widely applied in the fields of food preservative films, 3D printing materials and the like.

Drawings

FIG. 1 is a synthetic route diagram of the present invention;

FIG. 2 is the nuclear magnetic hydrogen spectrum of butyl rubber/polylactic acid graft polymer in the first embodiment of the present invention;

FIG. 3 is a butyl rubber, butyl rubber/polylactic acid polymer GPC curve according to example one of the present invention;

FIG. 4 is a DSC curve of butyl rubber/polylactic acid polymer in accordance with the first embodiment of the present invention.

Detailed Description

The invention is further explained below with reference to the drawings.

This detailed description is to be construed as illustrative only and is not limiting, since modifications will occur to those skilled in the art upon reading the preceding specification, and it is intended to be protected by the following claims.

Example one

As shown in fig. 1, a preparation method of a butyl rubber/polylactic acid graft polymer comprises the following steps:

a. 10 g of butyl rubber (0.89 mmol of isoprene unit, 23.9 ten thousand of number average molecular weight and 2.02 of molecular weight distribution) with an unsaturation degree of 0.5 percent are completely dissolved in 800ml of toluene and the temperature is kept to 30 percent^oC, adding a m-chloroperoxybenzoic acid toluene solution (8.9 mmol, 100 ml) under stirring, reacting for 6 hours, precipitating a product by using a large amount of ethanol, drying in vacuum, and drying to obtain epoxidized butyl rubber; rate of epoxidation>99 percent. The yield of the epoxybutyl rubber was 95%.

b. Completely dissolving 5g of epoxy butyl rubber (0.4 mmol of epoxy group) in 150ml of toluene, adding 0.2ml of 37% concentrated hydrochloric acid, reacting at room temperature for 6 hours, adding a large amount of deionized water, washing, and drying in vacuum to obtain hydroxylated butyl rubber; the conversion of the epoxy groups to hydroxyl groups was 97%.

c. 3g of hydroxybutyl rubber (0.24 mmol of hydroxyl) were completely dissolved in 200ml of toluene, L-lactide (3 g) and the catalyst Sn (oct)₂(stannous octoate, 0.24 mmol) was added, 95%^oAnd C, reacting for 6 hours, precipitating with a large amount of ethanol, and drying in vacuum to obtain the butyl rubber grafted polylactic acid copolymer. The polymer yield was 82%, the polymer fraction average molecular weight was 33.4 ten thousand, and the molecular weight distribution was 1.86.

As shown in fig. 2, the butyl rubber/polylactic acid graft polymer nuclear magnetic hydrogen spectrum of the present example; from this figure, it can be seen that Ha is hydrogen on the methyl group of the polylactic acid graft chain and Hb is hydrogen on the tertiary carbon of the polylactic acid graft chain, indicating that the synthesized polymer comprises a long polylactic acid chain.

As shown in fig. 3, the butyl rubber, butyl rubber/polylactic acid polymer GPC curves of the present example; from this figure, it can be seen that the butyl rubber/polylactic acid polymer curve is shifted to the right compared to butyl rubber, the number average molecular weight increases from 23.9 to 33.4 ten thousand, and the polymer GPC curve shows a monomodal distribution, indicating that the synthesis results in a graft block polymer, rather than a mixture of butyl rubber and polylactic acid.

As shown in fig. 4, DSC curve of butyl rubber/polylactic acid polymer of this example; from this figure, it can be seen that-65^oC is the glass transition temperature (Tg) of the butyl rubber backbone, 53^oC is polylactic acid graft segment Tg of 152^oC is the melting point (Tm) of the polylactic acid graft segment, which indicates that the butyl rubber/polylactic acid graft block polymer is successfully obtained.

Example two

As shown in fig. 1, a preparation method of a butyl rubber/polylactic acid graft polymer comprises the following steps:

a. 10 g of butyl rubber (1.78 mmol of isoprene unit, 25.2 ten thousand of number average molecular weight and 2.12 of molecular weight distribution) with an unsaturation degree of 1% was completely dissolved in 600ml of toluene, and the temperature was maintained at 30 DEG^oC, adding a m-chloroperoxybenzoic acid toluene solution (17.8 mmol, 200 ml) under stirring, reacting for 3 hours, precipitating a product by using a large amount of ethanol, drying in vacuum, and drying to obtain epoxidized butyl rubber; rate of epoxidation>99%。

b. Completely dissolving 5g of epoxy butyl rubber (0.85 mmol of epoxy group) in 150ml of toluene, adding 0.4ml of 37% concentrated hydrochloric acid, reacting at room temperature for 6 hours, adding a large amount of deionized water, washing, and drying in vacuum to obtain hydroxylated butyl rubber; the conversion of epoxy groups to hydroxyl groups was 80%.

c. 3g of hydroxybutyl rubber (0.5 mmol of hydroxyl) were completely dissolved in 200ml of toluene, L-lactide (1 g) and the catalyst Sn (oct)₂(stannous octoate, 0.51 mmol) was added, 95%^oAnd C, reacting for 6 hours, precipitating with a large amount of ethanol, and drying in vacuum to obtain the butyl rubber grafted polylactic acid copolymer. The yield of the polymer was 92%, the number average molecular weight was 31.4 ten thousand,molecular weight distribution 1.92.

EXAMPLE III

As shown in fig. 1, a preparation method of a butyl rubber/polylactic acid graft polymer comprises the following steps:

a. 10 g of butyl rubber (2.7 mmol of isoprene unit, number average molecular weight 23.9 ten thousand, molecular weight distribution 2.21) having an unsaturation degree of 1.5% was completely dissolved in 1000ml of toluene, and the temperature was maintained at 30 degrees^oC, adding a m-chloroperoxybenzoic acid toluene solution (27 mmol, 200 ml) under stirring, reacting for 2 hours, precipitating a product by using a large amount of ethanol, drying in vacuum, and drying to obtain epoxidized butyl rubber; rate of epoxidation>99%。

b. Completely dissolving 5g of epoxy butyl rubber (1.3 mmol of epoxy group) in 600ml of toluene, adding 0.6ml of 37% concentrated hydrochloric acid, reacting for 1 hour at room temperature, adding a large amount of deionized water, washing, and drying in vacuum to obtain hydroxylated butyl rubber; the conversion of epoxy groups to hydroxyl groups was 99%.

c. 3g of hydroxybutyl rubber (0.78 mmol of hydroxyl groups) were completely dissolved in 200ml of toluene, L-lactide (2 g) and the catalyst Sn (oct)₂(stannous octoate, 0.79 mmol) was added, 95%^oAnd C, reacting for 2 hours, precipitating with a large amount of ethanol, and drying in vacuum to obtain the butyl rubber grafted polylactic acid copolymer, wherein the yield of the copolymer is 78%, the number average molecular weight is 35.2 ten thousand, and the molecular weight distribution is 1.75.

Example four

As shown in fig. 1, a preparation method of a butyl rubber/polylactic acid graft polymer comprises the following steps:

a. 10 g of butyl rubber (3.5 mmol of isoprene unit, number average molecular weight 19.6 ten thousand, molecular weight distribution 2.06) with an unsaturation degree of 2% was completely dissolved in 500ml of toluene, and the temperature was maintained at 30%^oC, adding a m-chloroperoxybenzoic acid toluene solution (35 mmol, 300 ml) under stirring, reacting for 3 hours, precipitating a product by using a large amount of ethanol, drying in vacuum, and drying to obtain epoxidized butyl rubber; rate of epoxidation>99% and yield 98%.

b. Completely dissolving 5g of epoxy butyl rubber (1.8 mmol of epoxy group) in 150ml of toluene, adding 0.3 ml of 37% concentrated hydrochloric acid, reacting at room temperature for 3 hours, adding a large amount of deionized water, washing, and drying in vacuum to obtain hydroxylated butyl rubber; the epoxy groups are completely converted to hydroxyl groups.

c. 3g of hydroxybutyl rubber (1.1 mmol of hydroxyl groups) were completely dissolved in 200ml of toluene, L-lactide (4.3 g) and the catalyst Sn (oct)₂(stannous octoate, 1.1 mmol) was added, 95%^oC, reacting for 6 hours, precipitating by using a large amount of ethanol, and drying in vacuum, wherein the yield of the butyl rubber graft polymer is 85%, the number average molecular weight is 28.7 ten thousand, and the molecular weight distribution is 1.88.

EXAMPLE five

As shown in figure 1, a butyl rubber/polylactic acid graft polymer and a preparation method thereof comprise the following steps:

a. 10 g of butyl rubber (5.3 mmol of isoprene unit, 21.0 ten thousand of number average molecular weight and 2.08 of molecular weight distribution) with 3% of unsaturation was completely dissolved in 600ml of toluene and the temperature was kept constant at 30%^oC, adding a m-chloroperoxybenzoic acid toluene solution (53 mmol, 300 ml) under stirring, reacting for 3 hours, precipitating a product by using a large amount of ethanol, drying in vacuum, and drying to obtain epoxidized butyl rubber; rate of epoxidation>99%。

b. Completely dissolving 5g of epoxy butyl rubber (2.6 mmol of epoxy group) in 150ml of toluene, adding 0.4ml of 37% concentrated hydrochloric acid, reacting at room temperature for 6 hours, adding a large amount of deionized water, washing, and drying in vacuum to obtain hydroxylated butyl rubber; the conversion of epoxy groups to hydroxyl groups was 99%.

c. 3g of hydroxybutyl rubber (1.5 mmol of hydroxyl) were completely dissolved in 200ml of toluene, L-lactide (2 g) and the catalyst Sn (oct)₂(stannous octoate, 1.5 mmol) was added, 95%^oAnd C, reacting for 6 hours, precipitating with a large amount of ethanol, and drying in vacuum to obtain the butyl rubber grafted polylactic acid copolymer, wherein the yield of the copolymer is 83.6%, the number average molecular weight is 33.8 ten thousand, and the molecular weight distribution is 1.94.