阅读说明：本技术 一种环保塑料玩具制品制备方法 (Preparation method of environment-friendly plastic toy product ) 是由 钟锦祥 张泳高 叶长亮 钟继曦 邱锡珉 于 2021-08-18 设计创作，主要内容包括：本发明公开了一种环保塑料玩具制品制备方法,包括以下步骤：步骤1,制备聚氨酯预聚体：按量称取聚酯多元醇与异氰酸酯混合预聚反应,制备得到聚氨酯预聚体；步骤2,制备聚氨酯弹性体：按量称取扩链剂与聚氨酯预聚体混合均匀后,再加入催化剂进行聚合反应,制备得到聚氨酯弹性体；步骤3,制备聚氨酯母粒；步骤4,注塑成型：将聚氨酯母粒投入注塑机的料筒中,使用注塑模具硫化成型,得到环保塑料玩具制品。本发明中采用的聚氨酯类环保材料作为主基料,以传统的合成方法制备了一种环保塑料玩具材料。最终制备得到的聚氨酯除了保持较好的耐磨性和硬度外,在耐水性、耐酸碱性和耐老化性方面也得到了很大的改善。(The invention discloses a preparation method of an environment-friendly plastic toy product, which comprises the following steps: step 1, preparing a polyurethane prepolymer: weighing polyester polyol according to the amount, mixing the polyester polyol with isocyanate, and carrying out prepolymerization reaction to prepare a polyurethane prepolymer; step 2, preparing a polyurethane elastomer: weighing chain extender according to the amount, uniformly mixing the chain extender with the polyurethane prepolymer, and then adding a catalyst for polymerization reaction to prepare a polyurethane elastomer; step 3, preparing polyurethane master batches; step 4, injection molding: and (3) putting the polyurethane master batch into a charging barrel of an injection molding machine, and vulcanizing and molding by using an injection mold to obtain the environment-friendly plastic toy product. The environment-friendly plastic toy material is prepared by taking the polyurethane environment-friendly material as a main base material and adopting a traditional synthetic method. The finally prepared polyurethane not only maintains better wear resistance and hardness, but also is greatly improved in water resistance, acid and alkali resistance and aging resistance.)

1. A preparation method of an environment-friendly plastic toy product is characterized by comprising the following steps:

step 1, preparing a polyurethane prepolymer:

weighing polyester polyol according to the amount, mixing the polyester polyol with diisocyanate, carrying out prepolymerization reaction, and preparing a polyurethane prepolymer;

step 2, preparing a polyurethane elastomer:

weighing chain extender according to the amount, uniformly mixing the chain extender with the polyurethane prepolymer, and then adding a catalyst for polymerization reaction to prepare a polyurethane elastomer;

step 3, preparing polyurethane master batches;

placing the polyurethane elastomer in an open mill, heating to a molten state, adding a modifier, uniformly mixing, sequentially adding a plasticizer, an antioxidant, a light stabilizer and a flame retardant, uniformly mixing again, and performing extrusion granulation by an extruder to obtain polyurethane master batch;

step 4, injection molding:

putting the polyurethane master batch into a charging barrel of an injection molding machine, and vulcanizing and molding by using an injection mold to obtain an environment-friendly plastic toy product;

the polyurethane elastomer comprises the following raw material components in parts by weight:

55-75 parts of polyester polyol, 20-30 parts of diisocyanate, 1-3 parts of chain extender and 0.05-0.25 part of catalyst;

the polyurethane master batch comprises the following raw materials in parts by weight:

100 parts of polyurethane elastomer, 10-16 parts of modifier, 7-15 parts of plasticizer, 0.5-2 parts of antioxidant, 0.3-0.6 part of light stabilizer and 10-18 parts of flame retardant.

2. The method for preparing an environment-friendly plastic toy product according to claim 1, wherein in the step 1, the reaction temperature of the prepolymerization reaction is 45-60 ℃ and the reaction time is 1-3 h.

3. The method for preparing an environment-friendly plastic toy product according to claim 1, wherein in the step 1, the polyester polyol is polycarbonate diol having a number average molecular weight of 1000 to 4000.

4. The method for preparing an environment-friendly plastic toy product according to claim 1, wherein in the step 1, the diisocyanate is diphenylmethane diisocyanate or isophorone diisocyanate.

5. The method for preparing an environment-friendly plastic toy product according to claim 1, wherein in the step 2, the chain extender comprises a small-molecule diamine chain extender and a small-molecule diol chain extender, and the mass ratio of the small-molecule diamine chain extender to the small-molecule diol chain extender is 1: 0.2-0.5.

6. The method for preparing an environment-friendly plastic toy product according to claim 1, wherein in the step 3, the plasticizer is tributyl citrate or epoxidized soybean oil.

7. The method for preparing an environment-friendly plastic toy product according to claim 1, wherein in the step 3, the antioxidant is one of antioxidant 1135, antioxidant 3114 and antioxidant 1024.

8. The method for preparing an environment-friendly plastic toy product as claimed in claim 1, wherein in step 3, the light stabilizer is one of UV-328, UV-329 and UV-571.

9. The method for preparing an environment-friendly plastic toy product according to claim 1, wherein in the step 3, the flame retardant is obtained by mixing dimethyl methylphosphonate and ammonium polyphosphate according to a mass ratio of 1: 1.5-2.

10. The method for preparing an environment-friendly plastic toy product according to claim 1, wherein in the step 3, the modifying agent is modified bagasse pith, and the method for preparing the modified bagasse pith comprises the following steps:

s1, drying sugarcane pith, adding the dried sugarcane pith into a sodium hydroxide solution with the concentration of 0.1-0.5 mol/L, uniformly mixing, adding a silane coupling agent KH560, stirring at room temperature for 5-8 hours, filtering, washing a collected solid product to be neutral by using pure water, and drying to obtain epoxidized sugarcane pith; wherein the mass ratio of the bagasse pith to the silane coupling agent KH560 to the sodium hydroxide solution is 1: 1-1.5: 6-10;

s2, weighing polyacrylamide and deionized water, mixing the polyacrylamide and the deionized water into a reaction container, adding gamma-aminobutyric acid while stirring at room temperature, uniformly mixing, adjusting the pH value of a reaction solution to be 3.0-4.0, and continuously stirring for 3-5 hours to obtain a gamma-aminobutyrylated polyacrylamide mixed solution; wherein the mass ratio of the polyacrylamide to the deionized water is 1-5: 100, and the mass ratio of the gamma-aminobutyric acid to the polyacrylamide is 4.1-4.6: 1;

s3, adjusting the pH value of the gamma-aminobutyrylated polyacrylamide mixed solution to 8.0-9.0, adding epoxidized bagasse pith, uniformly mixing, heating to 45-55 ℃, stirring for reaction for 2-5 hours, filtering, washing the collected solid product to be neutral by using pure water, and drying to obtain modified bagasse pith; wherein the mass ratio of the epoxidized bagasse pith to the gamma-aminobutyrylated polyacrylamide mixed solution is 1: 16-24.

Technical Field

The invention relates to the field of environment-friendly materials, in particular to a preparation method of an environment-friendly plastic toy product.

Background

Along with the improvement of the living standard year by year, the environmental protection requirement on plastic products is gradually improved, the environment protection and low carbon become industry consensus, export manufacturers need to move ahead actively, toy enterprises owned by China are reduced from more than 8 thousand to more than 6 thousand in recent years, and plastic products which do not meet the requirement are subject to great export restriction.

The plastic toy not only needs to meet the requirement of unique shape, but also needs to be able to withstand the environment. The plastic toys made of traditional materials are not the main requirements of the current market, and the development and application of novel environment-friendly materials can improve the added value and the competitiveness of the plastic toys. The polyurethane material is an environment-friendly material with low flame heat, has better mechanical strength and wear resistance, but has defects in aging resistance, so that a polyurethane plastic toy with environment-friendly property and aging resistance needs to be developed.

Disclosure of Invention

Aiming at the problems that the plastic toy made of traditional materials in the prior art is not environment-friendly and is not aging-resistant, the invention aims to provide a preparation method of an environment-friendly plastic toy product.

The purpose of the invention is realized by adopting the following technical scheme:

a preparation method of an environment-friendly plastic toy product comprises the following steps:

step 1, preparing a polyurethane prepolymer:

weighing polyester polyol according to the amount, mixing the polyester polyol with diisocyanate, carrying out prepolymerization reaction, and preparing a polyurethane prepolymer;

step 2, preparing a polyurethane elastomer:

weighing chain extender according to the amount, uniformly mixing the chain extender with the polyurethane prepolymer, and then adding a catalyst for polymerization reaction to prepare a polyurethane elastomer;

step 3, preparing polyurethane master batches;

placing the polyurethane elastomer in an open mill, heating to a molten state, adding a modifier, uniformly mixing, sequentially adding a plasticizer, an antioxidant, a light stabilizer and a flame retardant, uniformly mixing again, and performing extrusion granulation by an extruder to obtain polyurethane master batch;

step 4, injection molding:

putting the polyurethane master batch into a charging barrel of an injection molding machine, and vulcanizing and molding by using an injection mold to obtain an environment-friendly plastic toy product;

the polyurethane elastomer comprises the following raw material components in parts by weight:

55-75 parts of polyester polyol, 20-30 parts of diisocyanate, 1-3 parts of chain extender and 0.05-0.25 part of catalyst;

the polyurethane master batch comprises the following raw materials in parts by weight:

100 parts of polyurethane elastomer, 10-16 parts of modifier, 7-15 parts of plasticizer, 0.5-2 parts of antioxidant, 0.3-0.6 part of light stabilizer and 10-18 parts of flame retardant.

Preferably, in the step 1, the reaction temperature of the prepolymerization reaction is 45-60 ℃, and the reaction time is 1-3 h.

Preferably, in the step 1, the polyester polyol is polycarbonate diol with the number average molecular weight of 1000-4000.

Preferably, in step 1, the diisocyanate is diphenylmethane diisocyanate or isophorone diisocyanate.

Preferably, in the step 2, the reaction temperature of the polymerization reaction is 70-85 ℃, and the reaction time is 3-5 h.

Preferably, in the step 2, the chain extender comprises a small molecular diamine chain extender and a small molecular diol chain extender, and the mass ratio of the small molecular diamine chain extender to the small molecular diol chain extender is 1: 0.2-0.5.

Preferably, the addition sequence of the chain extender is: mixing a micromolecular diamine chain extender with the polyurethane prepolymer, stirring and reacting for 0.5-1 h at the temperature of 70-85 ℃, and then adding a micromolecular diol chain extender to continue reacting.

Preferably, the small molecule diamine chain extender is one of 3, 3-dichloro-4, 4-diphenylmethane diamine, 4-diphenylmethane diamine and 3, 5-dimethylthio toluene diamine; the micromolecular dihydric alcohol chain extender is one of ethylene glycol, 1, 4-butanediol and 1, 2-propylene glycol.

Preferably, in the step 3, the mixing temperature is 180-190 ℃.

Preferably, in step 3, the plasticizer is tributyl citrate or epoxidized soybean oil.

Preferably, in step 3, the antioxidant is one of antioxidant 1135, antioxidant 3114 and antioxidant 1024.

Preferably, in step 3, the light stabilizer is one of UV-328, UV-329 and UV-571.

Preferably, in the step 3, the flame retardant is obtained by mixing dimethyl methylphosphonate and ammonium polyphosphate according to a mass ratio of 1: 1.5-2.

Preferably, in step 3, the modifying agent is modified pith, and the preparation method of the modified pith comprises the following steps:

s1, drying sugarcane pith, adding the dried sugarcane pith into a sodium hydroxide solution with the concentration of 0.1-0.5 mol/L, uniformly mixing, adding a silane coupling agent KH560, stirring at room temperature for 5-8 hours, filtering, washing a collected solid product to be neutral by using pure water, and drying to obtain epoxidized sugarcane pith; wherein the mass ratio of the bagasse pith to the silane coupling agent KH560 to the sodium hydroxide solution is 1: 1-1.5: 6-10;

s2, weighing polyacrylamide and deionized water, mixing the polyacrylamide and the deionized water into a reaction container, adding gamma-aminobutyric acid while stirring at room temperature, uniformly mixing, adjusting the pH value of a reaction solution to be 3.0-4.0, and continuously stirring for 3-5 hours to obtain a gamma-aminobutyrylated polyacrylamide mixed solution; wherein the mass ratio of the polyacrylamide to the deionized water is 1-5: 100, and the mass ratio of the gamma-aminobutyric acid to the polyacrylamide is 4.1-4.6: 1;

s3, adjusting the pH value of the gamma-aminobutyrylated polyacrylamide mixed solution to 8.0-9.0, adding epoxidized bagasse pith, uniformly mixing, heating to 45-55 ℃, stirring for reaction for 2-5 hours, filtering, washing the collected solid product to be neutral by using pure water, and drying to obtain modified bagasse pith; wherein the mass ratio of the epoxidized bagasse pith to the gamma-aminobutyrylated polyacrylamide mixed solution is 1: 16-24.

Preferably, the molecular weight of the polyacrylamide is 25-30 ten thousand.

The invention has the beneficial effects that:

1. the environment-friendly plastic toy material is prepared by taking the polyurethane environment-friendly material as a main base material and adopting a traditional synthetic method. Among them, polyurethane is obtained by polymerizing polyester polyol and diisocyanate, and has good wear resistance, high hardness, and good oil resistance and cold resistance, but has the disadvantages of poor water resistance, poor acid and alkali resistance, and poor aging resistance, and is easily hydrolyzed to cause strength reduction when used in a humid environment. Therefore, the invention uses the modifier to modify the polyurethane elastomer, the modifier uses the modified bagasse pith, and the modification process is to mix the modifier and the prepared polyurethane elastomer in a molten state and then add other auxiliary agents. The finally prepared polyurethane has better mechanical strength, and is also greatly improved in the aspects of water resistance, high temperature resistance and aging resistance.

2. The modifier of the invention uses self-made modified bagasse pith, which is the part removed in the utilization of bagasse waste and is difficult to reuse at present because of no interweaving force. According to the invention, researches show that although the sugarcane pith has no interweaving force, the sugarcane pith has rich branched chain structures, and if a certain group is grafted on the surface of the sugarcane pith, more utilization modes can be realized. However, the bagasse-based pith is soft and short, unlike conventional cellulose, and it is difficult to form grafts or polymers on the surface thereof.

Firstly, epoxidizing the surface of the bagasse pith by using epoxy silane under an alkaline condition, and activating the surface of the bagasse pith after treatment and grafting a large amount of epoxy groups; then, polyacrylamide is used for reacting with gamma-aminobutyric acid to generate gamma-aminobutyrylated polyacrylamide with terminal amino groups, and preparation is made for grafting on the surface of the sugarcane pith; then, gamma-aminobutyrylated polyacrylamide with terminal amino groups is used for carrying out mixed crosslinking reaction with the epoxidized bagasse pith, and the terminal amino groups on the gamma-aminobutyrylated polyacrylamide and epoxy groups of the epoxidized bagasse pith react due to better binding property, so that the surface of the bagasse pith is coated with the generated polymer. The polymer-coated sugarcane pith has more active groups and abundant branched structures, so that the crosslinking property is more excellent compared with other celluloses.

Detailed Description

For the purpose of more clearly illustrating the present invention and more clearly understanding the technical features, objects and advantages of the present invention, the technical solutions of the present invention will now be described in detail below, but are not to be construed as limiting the implementable scope of the present invention.

Bagasse is the main waste (24-27%) of sugar industry. The total yield of sugarcane in the southern sugarcane area is 7000 million tons, and the yield of sugarcane bagasse produced every year is about 2000 million tons. In terms of comprehensive utilization of bagasse, a long bagasse fraction (mainly, the cortex fraction of sugarcane) is commonly used for papermaking, while a short fiber and fines fraction (mainly, the core fraction of sugarcane, called sugarcane pith) cannot be used as a papermaking raw material. At present, the utilization rate of the sugarcane pith is very low, and the sugarcane pith is mainly used as auxiliary boiler fuel to burn and recover heat energy. However, the heat value of the sugarcane pith is low, great waste is easily caused, and certain pollution is caused to the environment by combusting the sugarcane pith. Therefore, how to effectively utilize the sugarcane pith and improve the added value of the sugarcane pith is a hot problem which needs to be solved urgently.

The invention is further described below with reference to the following examples.

Example 1

A preparation method of an environment-friendly plastic toy product comprises the following steps:

step 1, preparing a polyurethane prepolymer:

weighing polycarbonate diol and diphenylmethane diisocyanate according to the amount, mixing, and carrying out a pre-polymerization reaction to prepare a polyurethane prepolymer; wherein the number average molecular weight of the polycarbonate diol is 1000-4000; the reaction temperature of the prepolymerization reaction is 50 ℃, and the reaction time is 2 hours;

step 2, preparing a polyurethane elastomer:

weighing 3, 3-dichloro-4, 4-diphenylmethanediamine and ethylene glycol according to the weight, mixing the 3, 3-dichloro-4, 4-diphenylmethanediamine and the polyurethane prepolymer, stirring and reacting for 0.5-1 h at 78 ℃, then adding ethylene glycol, and then adding a catalyst for polymerization reaction to prepare a polyurethane elastomer; wherein the reaction temperature of the polymerization reaction is 78 ℃, and the reaction time is 4 hours; the mass ratio of 3, 3-dichloro-4, 4-diphenylmethane diamine to ethylene glycol is 1: 0.3;

step 3, preparing polyurethane master batches;

heating the polyurethane elastomer in an open mill to a molten state, adding the modified bagasse pith, uniformly mixing, sequentially adding tributyl citrate, an antioxidant 1135, UV-328 and a flame retardant, uniformly mixing again, and performing extrusion granulation by an extruder to obtain polyurethane master batches; wherein the mixing temperature is 185 ℃, and the flame retardant is obtained by mixing dimethyl methylphosphonate and ammonium polyphosphate according to the mass ratio of 1: 1.7;

step 4, injection molding:

putting the polyurethane master batch into a charging barrel of an injection molding machine, and vulcanizing and molding by using an injection mold to obtain an environment-friendly plastic toy product;

the polyurethane elastomer comprises the following raw material components in parts by weight:

65 parts of polycarbonate diol, 25 parts of diphenylmethane diisocyanate, 1.54 parts of 3, 3-dichloro-4, 4-diphenylmethane diamine, 0.46 part of ethylene glycol and 0.15 part of catalyst;

the polyurethane master batch comprises the following raw materials in parts by weight:

100 parts of polyurethane elastomer, 12 parts of modified bagasse pith, 10 parts of tributyl citrate, 11351.2 parts of antioxidant, UV-3280.5 parts and 14 parts of flame retardant.

The preparation method of the modified sugarcane pith comprises the following steps:

s1, drying sugarcane pith, adding the dried sugarcane pith into a sodium hydroxide solution with the concentration of 0.1-0.5 mol/L, uniformly mixing, adding a silane coupling agent KH560, stirring at room temperature for 5-8 hours, filtering, washing a collected solid product to be neutral by using pure water, and drying to obtain epoxidized sugarcane pith; wherein the mass ratio of the bagasse pith to the silane coupling agent KH560 to the sodium hydroxide solution is 1:1.2: 8;

s2, weighing polyacrylamide with the molecular weight of 25-30 ten thousand, mixing the polyacrylamide with deionized water in a reaction container, adding gamma-aminobutyric acid while stirring at room temperature, uniformly mixing, adjusting the pH value of a reaction solution to be 3.0-4.0, and continuously stirring for 3-5 hours to obtain a gamma-aminobutyrylated polyacrylamide mixed solution; wherein the mass ratio of the polyacrylamide to the deionized water is 3:100, and the mass ratio of the gamma-aminobutyric acid to the polyacrylamide is 4.3: 1;

s3, adjusting the pH value of the gamma-aminobutyrylated polyacrylamide mixed solution to 8.0-9.0, adding epoxidized bagasse pith, uniformly mixing, heating to 45-55 ℃, stirring for reaction for 2-5 hours, filtering, washing the collected solid product to be neutral by using pure water, and drying to obtain modified bagasse pith; wherein the mass ratio of the epoxidized bagasse pith to the gamma-aminobutyrylated polyacrylamide mixed solution is 1: 20.

Example 2

A preparation method of an environment-friendly plastic toy product comprises the following steps:

step 1, preparing a polyurethane prepolymer:

weighing polycarbonate diol and diphenylmethane diisocyanate according to the amount, mixing, and carrying out a pre-polymerization reaction to prepare a polyurethane prepolymer; wherein the number average molecular weight of the polycarbonate diol is 1000-4000; the reaction temperature of the prepolymerization reaction is 45 ℃, and the reaction time is 1 h;

step 2, preparing a polyurethane elastomer:

weighing 4, 4-diphenylmethane diamine and 1, 4-butanediol according to the weight, mixing the 4, 4-diphenylmethane diamine and the polyurethane prepolymer, stirring and reacting for 0.5-1 h at the temperature of 70-85 ℃, then adding the 1, 4-butanediol, and then adding a catalyst for polymerization reaction to prepare the polyurethane elastomer; wherein the reaction temperature of the polymerization reaction is 70-85 ℃, and the reaction time is 3-5 h; the mass ratio of the 4, 4-diphenylmethane diamine to the 1, 4-butanediol is 1: 0.2;

step 3, preparing polyurethane master batches;

heating the polyurethane elastomer in an open mill to a molten state, adding the modified bagasse pith, uniformly mixing, sequentially adding the epoxidized soybean oil, the antioxidant 3114, the UV-329 and the flame retardant, uniformly mixing again, and performing extrusion granulation by an extruder to obtain polyurethane master batches; wherein the mixing temperature is 180-190 ℃, and the flame retardant is obtained by mixing dimethyl methylphosphonate and ammonium polyphosphate according to the mass ratio of 1: 1.5;

step 4, injection molding:

putting the polyurethane master batch into a charging barrel of an injection molding machine, and vulcanizing and molding by using an injection mold to obtain an environment-friendly plastic toy product;

the polyurethane elastomer comprises the following raw material components in parts by weight:

55 parts of polycarbonate diol, 20 parts of diisocyanate, 0.83 part of 4, 4-diphenylmethane diamine, 0.17 part of 1, 4-butanediol and 0.05 part of catalyst;

the polyurethane master batch comprises the following raw materials in parts by weight:

100 parts of polyurethane elastomer, 10 parts of modified bagasse pith, 7 parts of epoxidized soybean oil, 31140.5 parts of antioxidant, UV-3290.3 parts and 10 parts of flame retardant.

In the step 3, the preparation method of the modified sugarcane pith comprises the following steps:

s1, drying sugarcane pith, adding the dried sugarcane pith into a sodium hydroxide solution with the concentration of 0.1-0.5 mol/L, uniformly mixing, adding a silane coupling agent KH560, stirring at room temperature for 5-8 hours, filtering, washing a collected solid product to be neutral by using pure water, and drying to obtain epoxidized sugarcane pith; wherein the mass ratio of the bagasse pith to the silane coupling agent KH560 to the sodium hydroxide solution is 1:1: 6;

s2, weighing polyacrylamide with the molecular weight of 25-30 ten thousand, mixing the polyacrylamide with deionized water in a reaction container, adding gamma-aminobutyric acid while stirring at room temperature, uniformly mixing, adjusting the pH value of a reaction solution to be 3.0-4.0, and continuously stirring for 3-5 hours to obtain a gamma-aminobutyrylated polyacrylamide mixed solution; wherein the mass ratio of polyacrylamide to deionized water is 1:100, and the mass ratio of gamma-aminobutyric acid to polyacrylamide is 4.1: 1;

s3, adjusting the pH value of the gamma-aminobutyrylated polyacrylamide mixed solution to 8.0-9.0, adding epoxidized bagasse pith, uniformly mixing, heating to 45-55 ℃, stirring for reaction for 2-5 hours, filtering, washing the collected solid product to be neutral by using pure water, and drying to obtain modified bagasse pith; wherein the mass ratio of the epoxidized bagasse pith to the gamma-aminobutyrylated polyacrylamide mixed solution is 1: 16.

Example 3

A preparation method of an environment-friendly plastic toy product comprises the following steps:

step 1, preparing a polyurethane prepolymer:

weighing polycarbonate diol and isophorone diisocyanate according to the amount, mixing, and carrying out a pre-polymerization reaction to prepare a polyurethane prepolymer; wherein the number average molecular weight of the polycarbonate diol is 1000-4000; the reaction temperature of the prepolymerization reaction is 60 ℃, and the reaction time is 3 hours;

step 2, preparing a polyurethane elastomer:

weighing 3, 5-dimethylthio toluenediamine and 1, 2-propylene glycol according to the weight, mixing the 3, 5-dimethylthio toluenediamine with a polyurethane prepolymer, stirring and reacting for 0.5-1 h at 70-85 ℃, then adding the 1, 2-propylene glycol, and then adding a catalyst for polymerization reaction to prepare a polyurethane elastomer; wherein the reaction temperature of the polymerization reaction is 70 ℃, and the reaction time is 3 hours; the mass ratio of the 3, 5-dimethylthiotoluenediamine to the 1, 2-propylene glycol is 1: 0.5;

step 3, preparing polyurethane master batches;

heating the polyurethane elastomer in an open mill to a molten state, adding the modified bagasse pith, uniformly mixing, sequentially adding tributyl citrate, an antioxidant 1024, UV-571 and a flame retardant, uniformly mixing again, and performing extrusion granulation by an extruder to obtain polyurethane master batches; wherein the mixing temperature is 180 ℃, and the flame retardant is obtained by mixing dimethyl methylphosphonate and ammonium polyphosphate according to the mass ratio of 1: 2;

step 4, injection molding:

putting the polyurethane master batch into a charging barrel of an injection molding machine, and vulcanizing and molding by using an injection mold to obtain an environment-friendly plastic toy product;

the polyurethane elastomer comprises the following raw material components in parts by weight:

75 parts of polyester polyol, 30 parts of diisocyanate, 2 parts of 3, 5-dimethylthiotoluenediamine, 1 part of 1, 2-propylene glycol and 0.25 part of catalyst;

the polyurethane master batch comprises the following raw materials in parts by weight:

100 parts of polyurethane elastomer, 16 parts of modified bagasse pith, 15 parts of plasticizer, 10242 parts of antioxidant, UV-5710.6 parts and 18 parts of flame retardant.

In the step 3, the preparation method of the modified sugarcane pith comprises the following steps:

s1, drying sugarcane pith, adding the dried sugarcane pith into a sodium hydroxide solution with the concentration of 0.1-0.5 mol/L, uniformly mixing, adding a silane coupling agent KH560, stirring at room temperature for 5-8 hours, filtering, washing a collected solid product to be neutral by using pure water, and drying to obtain epoxidized sugarcane pith; wherein the mass ratio of the bagasse pith to the silane coupling agent KH560 to the sodium hydroxide solution is 1:1.5: 10;

s2, weighing polyacrylamide with the molecular weight of 25-30 ten thousand, mixing the polyacrylamide with deionized water in a reaction container, adding gamma-aminobutyric acid while stirring at room temperature, uniformly mixing, adjusting the pH value of a reaction solution to be 3.0-4.0, and continuously stirring for 3-5 hours to obtain a gamma-aminobutyrylated polyacrylamide mixed solution; wherein the mass ratio of polyacrylamide to deionized water is 5:100, and the mass ratio of gamma-aminobutyric acid to polyacrylamide is 4.6: 1;

s3, adjusting the pH value of the gamma-aminobutyrylated polyacrylamide mixed solution to 8.0-9.0, adding epoxidized bagasse pith, uniformly mixing, heating to 45-55 ℃, stirring for reaction for 2-5 hours, filtering, washing the collected solid product to be neutral by using pure water, and drying to obtain modified bagasse pith; wherein the mass ratio of the epoxidized bagasse pith to the gamma-aminobutyrylated polyacrylamide mixed solution is 1: 24.

Comparative example 1

A preparation method of an environment-friendly plastic toy product comprises the following steps:

step 1, preparing a polyurethane prepolymer:

weighing polycarbonate diol and diphenylmethane diisocyanate according to the amount, mixing, and carrying out a pre-polymerization reaction to prepare a polyurethane prepolymer; wherein the number average molecular weight of the polycarbonate diol is 1000-4000; the reaction temperature of the prepolymerization reaction is 50 ℃, and the reaction time is 2 hours;

step 2, preparing a polyurethane elastomer:

weighing 3, 3-dichloro-4, 4-diphenylmethanediamine and ethylene glycol according to the weight, mixing the 3, 3-dichloro-4, 4-diphenylmethanediamine and the polyurethane prepolymer, stirring and reacting for 0.5-1 h at 78 ℃, then adding ethylene glycol, and then adding a catalyst for polymerization reaction to prepare a polyurethane elastomer; wherein the reaction temperature of the polymerization reaction is 78 ℃, and the reaction time is 4 hours; the mass ratio of 3, 3-dichloro-4, 4-diphenylmethane diamine to ethylene glycol is 1: 0.3;

step 3, preparing polyurethane master batches;

heating the polyurethane elastomer in an open mill to a molten state, adding bagasse pith, uniformly mixing, sequentially adding tributyl citrate, an antioxidant 1135, UV-328 and a flame retardant, uniformly mixing again, and performing extrusion granulation by an extruder to obtain polyurethane master batches; wherein the mixing temperature is 185 ℃, and the flame retardant is obtained by mixing dimethyl methylphosphonate and ammonium polyphosphate according to the mass ratio of 1: 1.7;

step 4, injection molding:

putting the polyurethane master batch into a charging barrel of an injection molding machine, and vulcanizing and molding by using an injection mold to obtain an environment-friendly plastic toy product;

the polyurethane elastomer comprises the following raw material components in parts by weight:

65 parts of polycarbonate diol, 25 parts of diphenylmethane diisocyanate, 1.54 parts of 3, 3-dichloro-4, 4-diphenylmethane diamine, 0.46 part of ethylene glycol and 0.15 part of catalyst;

the polyurethane master batch comprises the following raw materials in parts by weight:

100 parts of polyurethane elastomer, 12 parts of bagasse pith, 10 parts of tributyl citrate, 11351.2 parts of antioxidant, UV-3280.5 parts and 14 parts of flame retardant.

Comparative example 2

A preparation method of an environment-friendly plastic toy product comprises the following steps:

step 1, preparing a polyurethane prepolymer:

weighing polycarbonate diol and diphenylmethane diisocyanate according to the amount, mixing, and carrying out a pre-polymerization reaction to prepare a polyurethane prepolymer; wherein the number average molecular weight of the polycarbonate diol is 1000-4000; the reaction temperature of the prepolymerization reaction is 50 ℃, and the reaction time is 2 hours;

step 2, preparing a polyurethane elastomer:

weighing 3, 3-dichloro-4, 4-diphenylmethanediamine and ethylene glycol according to the weight, mixing the 3, 3-dichloro-4, 4-diphenylmethanediamine and the polyurethane prepolymer, stirring and reacting for 0.5-1 h at 78 ℃, then adding ethylene glycol, and then adding a catalyst for polymerization reaction to prepare a polyurethane elastomer; wherein the reaction temperature of the polymerization reaction is 78 ℃, and the reaction time is 4 hours; the mass ratio of 3, 3-dichloro-4, 4-diphenylmethane diamine to ethylene glycol is 1: 0.3;

step 3, preparing polyurethane master batches;

heating the polyurethane elastomer in an open mill to a molten state, sequentially adding tributyl citrate, an antioxidant 1135, UV-328 and a flame retardant, mixing uniformly again, and performing extrusion granulation by an extruder to obtain polyurethane master batches; wherein the mixing temperature is 185 ℃, and the flame retardant is obtained by mixing dimethyl methylphosphonate and ammonium polyphosphate according to the mass ratio of 1: 1.7;

step 4, injection molding:

putting the polyurethane master batch into a charging barrel of an injection molding machine, and vulcanizing and molding by using an injection mold to obtain an environment-friendly plastic toy product;

the polyurethane elastomer comprises the following raw material components in parts by weight:

65 parts of polycarbonate diol, 25 parts of diphenylmethane diisocyanate, 1.54 parts of 3, 3-dichloro-4, 4-diphenylmethane diamine, 0.46 part of ethylene glycol and 0.15 part of catalyst;

the polyurethane master batch comprises the following raw materials in parts by weight:

100 parts of polyurethane elastomer, 10 parts of tributyl citrate, 11351.2 parts of antioxidant, UV-3280.5 parts and 14 parts of flame retardant.

In order to more clearly illustrate the invention, the environment-friendly plastic toy products prepared in the embodiments 1 to 3 and the comparative examples 1 to 2 of the invention are tested in performance, wherein the tensile strength and the elongation at break are tested according to the standard GB/T528-; the heat aging treatment is carried out for 168 hours in an environment at 136 ℃; the high-temperature high-humidity treatment is carried out for 168 hours in an environment with the temperature of 85 ℃ and the humidity of 95 percent; the high temperature water treatment was carried out in water at 70 ℃ for 168h and the results of the test were recorded in table 1 as follows:

TABLE 1 aging resistance of different environment-friendly plastic toys

As can be seen from table 1, the environment-friendly plastic toy products prepared in embodiments 1 to 3 of the present invention have higher tensile strength and elongation at break, and can still maintain better tensile strength and elongation at break after thermal aging treatment, high-temperature high-humidity treatment, and high-temperature water treatment, which indicates that the environment-friendly plastic toy products prepared in embodiments 1 to 3 of the present invention have better mechanical strength and aging resistance.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.