CN110760082A - Preparation method of Vitrimer containing dynamic ester bond based on cellulose derivative - Google Patents

Abstract

The invention belongs to the technical field of Vitrimer preparation, and relates to a preparation method of Vitrimer containing dynamic ester bonds based on cellulose derivatives. The method specifically comprises the steps of taking a cellulose derivative containing carboxyl, various acid anhydrides and/or polycarboxylic acid as raw materials, taking glycidyl ether as a cross-linking agent, and carrying out esterification reaction on the carboxyl and epoxypropyl to obtain the Vitrimer film containing dynamic ester bonds. The Virimers prepared by the invention is a sustainable and environment-friendly Virimers.

Description

Preparation of a Vitrimer with Dynamic Ester Bonds Based on Cellulose Derivatives method

technical field

The invention belongs to the technical field of Vitrimer preparation, and relates to a preparation method of Vitrimer containing dynamic ester bonds based on cellulose derivatives.

Background technique

Plastics can be divided into thermoplastics and thermosets according to whether they are chemically cross-linked. Thermoplastics are generally linear polymers, which can soften and flow when heated, and can be plasticized repeatedly, but generally have low mechanical strength. Thermosetting plastics are polymers with a covalently cross-linked network structure. They have high mechanical strength and excellent solvent resistance, but they cannot be softened by heating, so they cannot be processed repeatedly. As plastics are more and more widely used in various fields, the problems caused to the environment also follow. According to some data, my country is a big emitter of plastic waste, and the annual waste discharge in coastal areas alone reaches 1.32-3.53 million Tons, ranking first in the world, waste plastics take a long time to degrade under natural conditions, and some even take hundreds of years. During the degradation process, harmful substances will also be produced, polluting soil and groundwater, and causing damage to the ecosystem. Serious destruction. In 2011, Leibler proposed a new concept of "Vitrimer" based on dynamic covalent bonds. Vitrimers contain a covalent network and have rheological properties similar to glass under external conditions, so they can be repeatedly processed [Montarnal D, CapelotM. , Tournilhac F, et al.Silica-like malleable materials from permanent organic networks[J].Science,2011,334(6058):965-8], Vitrimers have the characteristics of both thermosetting plastics and thermoplastics. Vitrimers involved include transesterification, reversible imine exchange, transalkylation based on polyionic liquid, disulfide exchange, and diketoamine bond exchange [Christensen P R, Scheuermann A M, Loeffler K E, et al. al.Closed-loop recycling of plastics enabled by dynamiccovalent diketoenamine bonds[J].Nature chemistry,2019,11(5):442.] et al.

The raw materials used in the current preparation of Vitrimers are mostly petroleum-based chemicals, and then a small amount of cellulose nanocrystals are added to enhance the mechanical properties. The preparation of nanocomposite materials in a heterogeneous system has the problems of non-renewable raw materials and unfriendly products for the environment, and, Traditional plastics, especially thermosetting plastics, are difficult to recycle. The extensive use of traditional plastics has caused harm to water resources, land resources, and the ecological environment. Therefore, the introduction of cellulose derivatives into the system is expected to solve the above shortcomings and deficiencies.

SUMMARY OF THE INVENTION

In order to solve the problems of the prior art, the present invention proposes a preparation method of Vitrimer containing dynamic ester bonds based on cellulose derivatives. Cellulose derivatives solve the above-mentioned problems brought by the preparation of Vitrimers from petroleum-based chemicals.

Technical scheme of the present invention:

A kind of preparation method of the Vitrimer containing dynamic ester bond based on cellulose derivatives, the steps are as follows:

Step 1: Mix the carboxyl-containing cellulose derivative with acid anhydride and/or polycarboxylic acid, add an organic solvent, and stir to fully dissolve the reactant to form a reaction solution.

Step 2: Pour the catalyst into the reaction solution obtained in Step 1, and stir to fully dissolve the catalyst.

Step 3: adding a glycidyl ether crosslinking agent to the reaction solution obtained in step 2, and reacting at 30-200° C. under the protection of N ₂ for 1-24 h to obtain a casting solution.

Step 4: Spread the casting solution obtained in Step 3 on the mold evenly, dry the solvent at 30-200°C, and then cure at 60-180°C for 1h-24h to obtain a Vitrimer film containing dynamic ester bonds.

The mass ratio of the carboxyl-containing cellulose derivative to acid anhydride and/or polycarboxylic acid is 1:9-9:1, preferably 3:7-7:3, more preferably 4:6-6:4.

The molar ratio of the sum of moles of carboxyl groups and acid anhydrides and/or polycarboxylic acids in the cellulose derivatives containing carboxyl groups to the epoxy functional groups in the glycidyl ether crosslinking agent is 1:3-10:1.

The molar ratio of the epoxy functional group to the catalyst in the glycidyl ether-based crosslinking agent is 0.01-30%, preferably 1-10%, more preferably 1-5%.

The organic solvent is N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, methyl ethyl ketone, acetone, pyridine, dioxane, ethyl acetate, chloroform, tetrahydrofuran or organic alcohols. solvent.

The glycidyl ether crosslinking agents are ethylene glycol diglycidyl ether (EDGE), poly(ethylene glycol) diglycidyl ether (PEGDE), poly(propylene glycol) diglycidyl ether (PPGDGE), epoxy Soybean oil (ESO), triglycidyl isocyanurate (TI), bisphenol F diglycidyl ether (BPF) or bisphenol A diglycidyl ether (DGEBA).

The catalyst is triazabicyclodecene (TBD), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 4-dimethylaminopyridine (DMAP) or zinc acetate (Zn(ac) ₂ ), preferably zinc acetate (Zn(ac) ₂ ).

The acid anhydride and/or polycarboxylic acid are maleic anhydride (MAH), 2-methylmaleic anhydride (MMA), 2,3-dimethylmaleic anhydride (DMMA), succinic anhydride (SA), 2-Dodecen-1-ylsuccinic anhydride (DSA), phthalic anhydride (PA) or sebacic acid (DA) or citric acid (CA).

The carboxyl-containing cellulose derivatives are cellulose acetate phthalate (CAP), cellulose succinate (CESA), carboxymethyl cellulose (CC) or carboxymethyl cellulose acetate butyrate (CMCAB). ).

Beneficial effects of the present invention:

The Vitrimer preparation method of the present invention alleviates the disadvantages of petroleum-based Vitrimers containing dynamic ester bonds, such as non-renewable raw materials and unfriendly environment, by introducing cellulose derivatives. Specifically, the Vitrimer film is obtained by the esterification reaction of carboxyl group and glycidyl group with cellulose, acid anhydride and polycarboxylic acid containing carboxyl group as raw materials and glycidyl ether as crosslinking agent.

Compared with the prior art, the present invention has the following beneficial effects:

1. The raw material used in the present invention, the cellulose derivative, has the characteristics of good biocompatibility, renewable raw material, low price and non-toxicity, so it is a kind of Vitrimers that conform to sustainable development and are environmentally friendly.

2. Due to the use of renewable biomass resources - cellulose, the dependence on petroleum resources can be reduced.

Description of drawings

Fig. 1 is the infrared spectrum comparison diagram of Vitrimer film (CAP-SA-DGEBA) prepared in Example 5 and bisphenol A diglycidyl ether (DGEBA);

Fig. 2 is the Vitrimer film TG contrast figure prepared in the film of cellulose acetate phthalate and Example 5;

Fig. 3 is the DSC diagram of the Vitrimer film prepared in Example 5;

Fig. 4 is the stress-strain curve diagram of the Vitrimer film prepared in Example 5;

Fig. 5 is a graph of the swelling of the Vitrimer film prepared in Example 5 with time in DMSO;

FIG. 6 is a stress relaxation curve diagram of the Vitrimer film prepared in Example 5 at 170°C.

Detailed ways

The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

Example 1:

Pour 0.60 g of cellulose acetate phthalate (CAP), 0.40 g of succinic anhydride (SA) and 5 ml of N,N-dimethylformamide (DMF) into a three-necked flask, and stir for about one hour to make the reactants fully Dissolve, add 0.01 g of zinc acetate (Zn(ac) ₂ ) catalyst, stir to fully dissolve the catalyst, then add 1.04 g of bisphenol A diglycidyl ether (DGEBA), react at 30°C under the protection of N ₂ for 24 h, stop the reaction, Obtain the casting liquid. The obtained casting liquid was poured into a polytetrafluoroethylene mold, so that the casting liquid was spread evenly on the mold, placed on a heating plate at 60 °C for 12 hours, and heated at 70 °C to cure for 3 hours to obtain a yellow-brown film.

Example 2:

Except 0.80g of cellulose acetate phthalate (CAP), 0.20g of citric acid (CA), 0.83g of bisphenol A diglycidyl ether (DGEBA), and 0.05g of (Zn(ac) ₂ ) catalyst, other preparation conditions Consistent with Example 1.

Example 3:

The preparation conditions were the same as those in Example 1, except that 0.90 g of cellulose acetate phthalate (CAP), 0.10 g of citric acid (CA), and 0.62 g of bisphenol A diglycidyl ether (DGEBA) were used.

Example 4:

Pour 0.60 g of cellulose acetate phthalate (CAP), 0.40 g of succinic anhydride (SA) and 5 ml of N,N-dimethylformamide (DMF) into a three-necked flask, and stir for about one hour to make the reactants fully Dissolve, add 0.02g of zinc acetate (Zn(ac) ₂ ) catalyst, magnetic stirring to make the catalyst fully dissolved, then add 1.09g of bisphenol A diglycidyl ether (DGEBA), react for 1h at 70°C and under the protection of N ₂ to stop the reaction , to obtain the casting liquid. Pour the obtained casting liquid into a polytetrafluoroethylene mold, spread the casting liquid evenly on the mold, put it at 60 °C to bake for 12 hours, gradually increase the temperature to 70 °C, 90 °C, and 110 °C and keep it at each temperature. After 2h, a yellow-brown film was obtained.

Example 5:

Except for 0.60 g of cellulose acetate phthalate (CAP), 0.40 g of succinic anhydride (SA) and 0.96 g of bisphenol A diglycidyl ether (DGEBA), other preparation conditions were the same as those in Example 4.

Illustrated in conjunction with the accompanying drawings, Fig. 1 is a comparison diagram of the infrared spectra of the Vitrimer film (CAP-SA-DGEBA) prepared in Example 5 and bisphenol A diglycidyl ether (DGEBA), and the peak position of the epoxy group is at ^{916cm- 1} , it can be seen from the infrared spectrum that CAP-SA-DGEBA has no peak at 916cm ^-1 , and at the same time, in the infrared spectrum of CAP-SA-DGEBA, it can be seen that there is an obvious peak at 1726cm ^-1 , is classified as the out-peak of ester carbonyl, and the infrared spectrum results show that epoxy group has reacted with carboxyl group and acid anhydride to generate ester bond; Fig. 2 is the film of cellulose acetate phthalate and the Vitrimer film TG prepared in Example 5 From the comparison diagram, it can be seen that the thermal stability of the Vitrimer film after cross-linking is greatly improved compared with that of cellulose acetate phthalate; Figure 3 is the DSC diagram of the Vitrimer film prepared in Example 5, and it can be seen that The glass transition temperature of the film is 31°C; Figure 4 is the stress-strain curve diagram of the Vitrimer film prepared in Example 5. The film thickness is 0.5mm and the width is about 10mm. It can be seen that the breaking strength of the film can reach more than 14MPa, and the fracture The elongation rate is more than 15%; Figure 5 is a graph of the swelling of the Vitrimer film prepared in Example 5 in DMSO at room temperature with time, and it can be seen that the swelling rate basically does not change after 6h; Figure 6 is prepared in Example 5 The stress relaxation curve of the Vitrimer film at 170 °C shows that the film has stress relaxation.

Example 6:

Except for 0.70 g of cellulose acetate phthalate (CAP), 0.30 g of succinic anhydride (SA), and 0.81 g of bisphenol A diglycidyl ether (DGEBA), other conditions were the same as those in Example 4.

Example 7:

0.80 g of cellulose acetate phthalate (CAP), 0.20 g of succinic anhydride (SA), and 0.68 g of bisphenol A diglycidyl ether (DGEBA) were added to the feed, and other conditions were the same as those in Example 4.

Example 8:

0.9 g of cellulose acetate phthalate (CAP), 0.10 g of succinic anhydride (SA), and 0.54 g of bisphenol A diglycidyl ether (DGEBA) were added to the feed, and other conditions were the same as those in Example 4.

Example 9:

Pour 0.10 g of cellulose acetate phthalate (CAP), 0.90 g of citric acid (CA) and 200 ml of N,N-dimethylformamide (DMF) into a three-necked flask, and stir for about an hour to fully dissolve the reactants , 0.32 g of zinc acetate (Zn(ac) ₂ ) catalyst was added, the catalyst was fully dissolved by magnetic stirring, then 0.51 g of ethylene glycol diglycidyl ether (EGDE) was added, and the reaction was carried out under the protection of N ₂ at 80 °C for 1 h, and the reaction was stopped to obtain casting fluid. Pour the obtained casting liquid into a polytetrafluoroethylene mold, spread the casting liquid evenly on the mold, put it at 30 °C to bake for 12 hours, gradually increase the temperature to 60 °C, 180 °C and keep it at each temperature for 3 hours, to obtain Dark tan film.

Example 10:

0.80 g of cellulose acetate phthalate (CAP), 0.20 g of citric acid (CA), and 0.41 g of ethylene glycol diglycidyl ether (EGDE) were added to the feed, and other conditions were the same as those in Example 9.

Example 11:

0.90 g of cellulose acetate phthalate (CAP), 0.10 g of citric acid (CA), and 0.30 g of ethylene glycol diglycidyl ether (EGDE) were added to the feed, and other conditions were the same as those in Example 9.

Example 12:

Pour 0.70 g of cellulose acetate phthalate (CAP), 0.30 g of citric acid (CA) and 10 ml of N,N-dimethylformamide (DMF) into a three-necked flask, stir for about an hour to fully dissolve the reactants , 0.01 g of zinc acetate (Zn(ac) ₂ ) catalyst was added, the catalyst was fully dissolved by magnetic stirring, then 1.47 g of polyethylene glycol diglycidyl ether (PEGDE) was added, and the reaction was carried out under the protection of N ₂ at 200 ° C for 2 h to stop the reaction. , to obtain the casting liquid. The obtained casting liquid was poured into a polytetrafluoroethylene mold, and the casting liquid was spread evenly on the mold, dried at 80° C. for 2 hours, and heated at 200° C. for 3 hours to obtain a dark yellow-brown film.

Example 13:

0.80 g of cellulose acetate phthalate (CAP), 0.20 g of citric acid (CA), and 1.17 g of polyethylene glycol diglycidyl ether (PEGDE) were added to the feed, and other conditions were the same as those in Example 12.

Example 14:

0.90 g of cellulose acetate phthalate (CAP), 0.10 g of citric acid (CA), and 0.87 g of polyethylene glycol diglycidyl ether (PEGDE) were added to the feed, and other conditions were the same as those in Example 12.

Example 15:

Pour 0.70 g of cellulose acetate phthalate (CAP), 0.30 g of succinic anhydride (SA) and 15 ml of N,N-dimethylformamide (DMF) into a three-necked flask, and stir for about one hour to make the reactants fully Dissolve, add 0.02 g of zinc acetate (Zn(ac) ₂ ) catalyst, magnetic stirring to make the catalyst fully dissolved, then add 0.40 g of ethylene glycol diglycidyl ether (EGDE), react for 1 h under the protection of N ₂ at 200 ° C, and stop the reaction , to obtain the casting liquid. The obtained casting liquid was poured into a polytetrafluoroethylene mold to spread the casting liquid evenly on the mold, dried at 200 °C for 1 h, and heated to 180 °C for 2 h to solidify to obtain a dark yellow-brown film.

Example 16:

0.80 g of cellulose acetate phthalate (CAP), 0.20 g of succinic anhydride (SA), and 0.33 g of ethylene glycol diglycidyl ether (EGDE) were added to the feed, and other conditions were the same as those in Example 15.

Example 17:

0.90 g of cellulose acetate phthalate (CAP), 0.10 g of succinic anhydride (SA), and 0.27 g of ethylene glycol diglycidyl ether (EGDE) were added to the feed, and other conditions were the same as those in Example 15.

Example 18:

Pour 0.50 g of cellulose acetate phthalate (CAP), 0.50 g of succinic anhydride (SA) and 5 ml of N,N-dimethylformamide (DMF) into a three-necked flask, and stir for about one hour to make the reactants fully Dissolve, add 0.10g of zinc acetate (Zn(ac) ₂ ) catalyst, magnetic stirring to fully dissolve the catalyst, then add 1.54g of polyethylene glycol diglycidyl ether (PEGDE), react for 3h under the protection of N ₂ at 80°C, stop the reaction , to obtain the casting liquid. The obtained casting liquid was poured into a polytetrafluoroethylene mold to spread the casting liquid evenly on the mold, dried at 70° C. for 12 hours, and heated to 100° C. to cure for 1 h to obtain a dark yellow-brown film.

Example 19:

0.60 g of cellulose acetate phthalate (CAP), 0.40 g of succinic anhydride (SA), and 1.34 g of polyethylene glycol diglycidyl ether (PEGDE) were added to the feed, and other conditions were the same as those in Example 18.

Example 20:

0.70 g of cellulose acetate phthalate (CAP), 0.30 g of succinic anhydride (SA), and 1.15 g of polyethylene glycol diglycidyl ether (PEGDE) were added to the feed, and other conditions were the same as those in Example 18.

Example 21:

0.80 g of cellulose acetate phthalate (CAP), 0.20 g of succinic anhydride (SA), and 0.96 g of polyethylene glycol diglycidyl ether (PEGDE) were added to the feed, and other conditions were the same as in Example 18.

Example 22:

0.90 g of cellulose acetate phthalate (CAP), 0.10 g of succinic anhydride (SA), and 0.77 g of polyethylene glycol diglycidyl ether (PEGDE) were added to the feed, and other conditions were the same as in Example 18.

Example 23:

Pour 0.70 g of cellulose acetate phthalate (CAP), 0.30 g of sebacic acid (DA) and 5 ml of N,N-dimethylformamide (DMF) into a three-necked flask, and stir for about one hour to make the reactants fully Dissolve, add 0.02 g of zinc acetate (Zn(ac) ₂ ) catalyst, magnetic stirring to make the catalyst fully dissolved, then add 0.81 g of bisphenol A diglycidyl ether (DGEBA), react under the protection of N ₂ at 90 ° C for 3 h, stop the reaction, Obtain the casting liquid. The obtained casting liquid was poured into a polytetrafluoroethylene mold, so that the casting liquid was spread evenly on the mold, dried at 30 °C for 12 h, and gradually heated at 90 °C for 24 h to obtain a yellow-brown film.

Example 24:

0.80 g of cellulose acetate phthalate (CAP), 0.20 g of sebacic acid (DA), and 0.67 g of bisphenol A diglycidyl ether (DGEBA) were added to the feed, and other conditions were the same as those in Example 23.

Example 25:

0.90 g of cellulose acetate phthalate (CAP), 0.10 g of sebacic acid (DA), and 0.54 g of bisphenol A diglycidyl ether (DGEBA) were added to the feed, and other conditions were the same as those in Example 23.

Example 26:

Pour 0.50 g of succinylated cellulose (CESA), 0.50 g of succinic anhydride (SA) and 5 ml of N,N-dimethylformamide (DMF) into a three-necked flask, stir for about one hour to fully dissolve the reactants, Add 0.02 g of zinc acetate (Zn(ac) ₂ ) catalyst, magnetic stirring to fully dissolve the catalyst, then add 1.09 g of bisphenol A diglycidyl ether (DGEBA), react at 70° C. under the protection of N ₂ for 5 h, stop the reaction, and obtain casting fluid. Pour the obtained casting liquid into a polytetrafluoroethylene mold, spread the casting liquid evenly on the mold, put it at 60 °C to bake for 12 hours, gradually increase the temperature to 70 °C, 90 °C, and 110 °C and keep it at each temperature. After 2h, a yellow-brown film was obtained.

Example 27:

Pour 0.50 g of carboxymethyl cellulose (CC), 0.50 g of succinic anhydride (SA) and 5 ml of N,N-dimethylformamide (DMF) into a there-necked flask, stir for about an hour to fully dissolve the reactants, Add 0.02 g of zinc acetate (Zn(ac) ₂ ) catalyst, magnetic stirring to fully dissolve the catalyst, then add 2.18 g of bisphenol A diglycidyl ether (DGEBA), react at 70° C. under the protection of N ₂ for 5 h, stop the reaction, and obtain casting fluid. Pour the obtained casting liquid into a polytetrafluoroethylene mold, spread the casting liquid evenly on the mold, put it at 60 °C to bake for 12 hours, gradually increase the temperature to 70 °C, 90 °C, and 110 °C and keep it at each temperature. After 2h, a yellow-brown film was obtained.

Example 28:

Pour 0.60 g of cellulose acetate phthalate (CAP), 0.40 g of succinic anhydride (SA) and 5 ml of N,N-dimethylformamide (DMF) into a three-necked flask, and stir for about one hour to make the reactants fully Dissolve, add 0.01 g of zinc acetate (Zn(ac) ₂ ) catalyst, stir to fully dissolve the catalyst, then add 0.10 g of bisphenol A diglycidyl ether (DGEBA), react at 30 ° C under the protection of N ₂ for 24 h, stop the reaction, Obtain the casting liquid. The obtained casting liquid was poured into a polytetrafluoroethylene mold, so that the casting liquid was spread evenly on the mold, placed on a heating plate at 60 °C for 12 hours, and heated at 70 °C to cure for 3 hours to obtain a yellow-brown film.

Example 29:

Pour 0.60 g of cellulose acetate phthalate (CAP), 0.40 g of succinic anhydride (SA) and 5 ml of N,N-dimethylformamide (DMF) into a three-necked flask, and stir for about one hour to make the reactants fully Dissolve, add 0.01 g of zinc acetate (Zn(ac) ₂ ) catalyst, stir to fully dissolve the catalyst, then add 2.85 g of bisphenol A diglycidyl ether (DGEBA), react at 30 ° C under the protection of N ₂ for 24 h, stop the reaction, Obtain the casting liquid. The obtained casting liquid was poured into a polytetrafluoroethylene mold, so that the casting liquid was spread evenly on the mold, placed on a heating plate at 60 °C for 12 hours, and heated at 70 °C to cure for 3 hours to obtain a yellow-brown film.

Claims (3)

1. a preparation method of the Vitrimer containing dynamic ester bond based on cellulose derivative, is characterized in that, step is as follows: Step 1: Mix the carboxyl-containing cellulose derivative with acid anhydride and/or polycarboxylic acid, add an organic solvent, and stir to fully dissolve the reactant to form a reaction solution; Step 2: Pour the catalyst into the reaction solution obtained in Step 1, and stir to fully dissolve the catalyst; Step 3: adding a glycidyl ether crosslinking agent to the reaction solution obtained in step 2, and reacting at 30-200° C. under the protection of N ₂ for 1-24 h to obtain a casting solution; Step 4: Spread the casting solution obtained in Step 3 on the mold evenly, dry the solvent at 30-200°C, and then cure at 60-180°C for 1h-24h to obtain a Vitrimer film containing dynamic ester bonds. 2. a kind of preparation method of the Vitrimer containing dynamic ester bond based on cellulose derivatives according to claim 1, is characterized in that, The mass ratio of the carboxyl-containing cellulose derivative to acid anhydride and/or polycarboxylic acid is 1:9-9:1; The molar ratio of the molar sum of the carboxyl group and the acid anhydride and/or polycarboxylic acid in the cellulose derivative containing the carboxyl group to the epoxy functional group in the glycidyl ether crosslinking agent is 1:3-10:1; The molar ratio of the epoxy functional group to the catalyst in the glycidyl ether crosslinking agent is 0.01-30%. 3. a kind of preparation method of the Vitrimer containing dynamic ester bond based on cellulose derivative according to claim 1 and 2, is characterized in that, The organic solvent is N,N-dimethylformamide, dimethyl sulfoxide, acetonitrile, methyl ethyl ketone, acetone, pyridine, dioxane, ethyl acetate, chloroform, tetrahydrofuran or alcohol organic solvent. solvent; The glycidyl ether crosslinking agents are ethylene glycol diglycidyl ether, poly(ethylene glycol) diglycidyl ether, poly(propylene glycol) diglycidyl ether, epoxy soybean oil, and triglycidyl isocyanurate. Esters, bisphenol F diglycidyl ether or bisphenol A diglycidyl ether; The catalyst is triazabicyclodecene, 1,5-diazabicyclo[4.3.0]non-5-ene, 4-dimethylaminopyridine or zinc acetate; Described acid anhydride and/or polybasic carboxylic acid are maleic anhydride, 2-methyl maleic anhydride, 2,3-dimethyl maleic anhydride, succinic anhydride, 2-dodecen-1-yl butanedi anhydride, phthalic anhydride or sebacic acid or citric acid; The carboxyl-containing cellulose derivatives are cellulose acetate phthalate, cellulose succinate, carboxymethyl cellulose or carboxymethyl cellulose acetate butyrate.

Images