阅读说明：本技术 一种热塑性聚氨酯弹性体材料及其制备方法和应用 (Thermoplastic polyurethane elastomer material and preparation method and application thereof ) 是由 刘洋子健 王建辉 黄岐善 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种热塑性聚氨酯弹性体材料及其制备方法,其由包含以下质量百分比的原料制备得到：(1)线性含硫二元醇20-60％、优选40-50％；(2)二异氰酸酯25-70％、优选30-45％；(3)小分子二元醇2-10％、优选2-5％；(4)含溴扩链剂5-40％、优选10-20％；以上百分数以原料的总质量为基准计。本发明所制备的热塑性聚氨酯材料透光率大于90％,折射指数大于1.6。本发明所制备的热塑性聚氨酯弹性体材料可应用于制备汽车、医疗、服饰、电子、光学领域的薄膜或片材。(The invention discloses a thermoplastic polyurethane elastomer material and a preparation method thereof, wherein the thermoplastic polyurethane elastomer material is prepared from the following raw materials in percentage by mass: (1) linear sulfur-containing diols 20 to 60%, preferably 40 to 50%; (2) 25-70%, preferably 30-45% of diisocyanate; (3) 2-10% of small molecular dihydric alcohol, preferably 2-5%; (4) bromine-containing chain extenders in the range of 5 to 40%, preferably 10 to 20%; the percentages are based on the total mass of the raw materials. The light transmittance of the thermoplastic polyurethane material prepared by the invention is more than 90%, and the refractive index is more than 1.6. The thermoplastic polyurethane elastomer material prepared by the invention can be applied to preparing films or sheets in the fields of automobiles, medical treatment, clothes, electronics and optics.)

1. A thermoplastic polyurethane elastomer material is prepared from the following raw materials in percentage by mass:

(1) linear sulfur-containing diols 20 to 60%, preferably 40 to 50%;

(2) 25-70%, preferably 30-45% of diisocyanate;

(3) 2-10%, preferably 2-5% of small molecule dihydric alcohol with number average molecular weight of 50-800;

(4) bromine-containing chain extenders in the range of 5 to 40%, preferably 10 to 20%;

the percentages are based on the total mass of the raw materials.

2. The thermoplastic polyurethane elastomer material according to claim 1, wherein the diisocyanate is one or more of toluene diisocyanate, diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, 3 ' -dimethyl-4, 4 ' -biphenyl diisocyanate, cyclohexanedimethylene diisocyanate, 4 ' -dicyclohexylmethane diisocyanate, 3 ' -dimethyl-4, 4 ' -diphenylmethane diisocyanate;

preferably one or more of toluene diisocyanate, diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, 3 '-dimethyl-4, 4' -biphenyl diisocyanate, and 3,3 '-dimethyl-4, 4' -diphenylmethane diisocyanate.

3. The thermoplastic polyurethane elastomer material as claimed in claim 1, wherein the linear sulfur-containing diol has a number average molecular weight of 500-4000g/mol, preferably 800-2000 g/mol.

4. The thermoplastic polyurethane elastomer material according to any one of claims 1 to 3, wherein the linear sulfur-containing diol has the general structural formula:

wherein a and b are 0, 1 or 2, and both can not be 0 at the same time, preferably 1 or 2, and more preferably 2;

wherein n is a natural number from 2 to 20, preferably n is 2,4,6, 8;

wherein A1 represents a para-phenyl group, a meta-phenyl group or a straight or branched alkyl group having a backbone of 1 to 5 carbon atoms; a2 represents a para-phenyl group, a meta-phenyl group or a straight or branched alkyl group having a backbone of 1 to 5 carbon atoms.

5. The thermoplastic polyurethane elastomer material according to claim 4, wherein the linear sulfur-containing diol is obtained by reacting a diol with a dibasic acid, wherein the diol is selected from bis (2-hydroxyethyl) disulfide, 4 '-dihydroxydiphenyl disulfide, 3' -dihydroxydiphenyl disulfide, butanediol, propylene glycol or ethylene glycol;

the dibasic acid is selected from 3,3 '-thiodipropionic acid, 4' -dithiodibutanoic acid, 3 '-dithiodipropionic acid, 4' -dithiodibenzoic acid, 3 '-dicarboxydiphenyl disulfide, 2' -dithiodipropionic acid, succinic acid, adipic acid and azelaic acid.

6. The thermoplastic polyurethane elastomer material according to any one of claims 1 to 5, wherein the small molecule diol is selected from one or more of ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, diethylene glycol, 1, 2-propanediol, methyl pentanediol, 1, 4-cyclohexanediol, neopentyl glycol, and terephthalyl alcohol;

preferably one or more of 1, 3-propanediol, 1, 4-butanediol and 1, 6-hexanediol.

7. The thermoplastic polyurethane elastomer material as described in any one of claims 1 to 6, wherein the chain extender containing bromine is one or more of a diol containing bromine, having a number average molecular weight of 100-500, preferably 150-400, more preferably 2-bromo-1, 3-propanediol, 3-bromo-1, 2-propanediol, 4-bromo-1, 2-butanediol, 4-bromo-1, 3-butanediol, dibromobutenediol, 1, 4-dibromo-2, 3-butanediol, 2, 3-dibromo-1, 4-butanediol, dibromoneopentyl glycol;

further preferred is one or more of 4-bromo-1, 3-butanediol, dibromobutenediol, dibromoneopentyl glycol, and 2, 3-dibromo-1, 4-butanediol.

8. Thermoplastic polyurethane elastomer material according to any one of claims 1 to 7, characterised in that the molar ratio of-NCO functional groups to-OH functional groups in the raw materials used is between 0.80 and 1.20, preferably between 0.98 and 1.02.

9. The thermoplastic polyurethane elastomer material according to claims 1 to 8, wherein the thermoplastic polyurethane has a light transmittance of more than 88%, a refractive index of more than 1.58, preferably a light transmittance of more than 90%, and a refractive index of more than 1.60, according to the test standards ASTM D1003 and ASTM D542.

10. The method for preparing the thermoplastic polyurethane elastomer according to any one of claims 1 to 9, wherein the continuous production is carried out by adopting a one-step method, and comprises the steps of storing the raw materials and the catalyst in a raw material storage tank at a fixed temperature, wherein the temperature of the storage tank is 80-120 ℃, metering and mixing the raw materials and the catalyst by a casting machine, feeding the raw materials and the catalyst into a double-screw extruder for reaction, setting the temperature of the extruder between 140 ℃ and 230 ℃, drying the raw materials after extrusion and granulation, and processing the dried thermoplastic polyurethane particles into a film or a sheet by a casting machine or a calendar; the catalyst is preferably selected from one or more of organic tin, organic bismuth, organic lead, organic zinc and organic amine; the addition amount of the catalyst is 0.05-0.1% of the total mass of the raw materials.

11. The thermoplastic polyurethane elastomer material according to any one of claims 1 to 10 or the thermoplastic polyurethane elastomer material produced by the production method according to claim 10 is used for producing films or sheets for automotive, medical, apparel, electronics, and optical fields.

Technical Field

The invention relates to the field of thermoplastic polyurethane elastomers, in particular to a thermoplastic polyurethane elastomer material, a preparation method and application thereof, which have the characteristics of high refraction and high transparency and are particularly suitable for preparing optical sheets and films.

Background

Polyurethane materials are widely used in the automobile industry, the mechanical industry, the medical health, the transportation industry and other industries because of their excellent mechanical properties, wear resistance, oil resistance, insulating properties and the like. The application field of the thermoplastic polyurethane material is enlarged year by year and the dosage is rapidly increased due to the excellent processing performance and rich processing modes. Although the common thermoplastic polyurethane material has the advantages, the optical refractive index of the common thermoplastic polyurethane material is lower, and is usually 1.44-1.53. When the material is applied to the optical field, the thickness of sheets, films and the like is obviously increased compared with that of high-refractive-index materials, which is obviously undesirable, and thus the application prospect in the field is severely limited.

At present, there are two main methods for improving the refractive index of the material: the first method adds a high refractive index blending aid to the material to increase the optical refractive index of the material, such as: chinese patent CN02139164.5 improves the refractive index of the material by adding nano metal oxide or sulfide to the polyurethane material. However, the auxiliary agent can improve the refractive index of the material, and simultaneously, the light transmittance and the like of the material are remarkably reduced, so that the comprehensive performance of the resin is poor and the like.

The second method is to introduce sulfur atoms into the resin to improve the refractive property of the material, and there are many related patents, such as: chinese patent CN201610270321 improves the refractive index of the material by using 2, 3-dimercaptoethylthiopropanethiol. However, the general functionality of the mercaptan used in the above patent is not less than 3, so that a large amount of chemical crosslinking is formed in the material, and the obtained polyurethane material is not a thermoplastic polyurethane elastomer, so that the material cannot be subjected to secondary processing molding and the like.

Therefore, the preparation of thermoplastic polyurethane elastomer materials with high refraction and high transparency becomes a problem to be solved urgently in the industry.

Disclosure of Invention

The invention aims to provide a thermoplastic polyurethane elastomer material and application thereof, wherein the thermoplastic polyurethane elastomer material has high refractive index and high transparency, has good processing performance and comprehensive performance, and can be used for preparing films or sheets in the fields of automobiles, medical treatment, clothes and electronics, in particular to materials such as films, test pieces and the like which can meet the performance requirements in the optical field.

The invention also aims to provide the preparation method of the thermoplastic polyurethane elastomer material, which adopts a one-step method for continuous production and has simple and easy process.

In order to achieve the purpose, the invention provides the following technical scheme:

in the experimental process, we surprisingly found that the refractive index of the thermoplastic polyurethane elastomer material can be well improved by adding a certain amount of bromine-containing chain extender while using sulfur-containing diol, and meanwhile, the prepared thermoplastic polyurethane material also has higher transparency due to the existence of branched chain structures in the sulfur-containing diol and the bromine-containing chain extender.

A thermoplastic polyurethane elastomer material is prepared from the following raw materials in percentage by mass:

(1) linear sulfur-containing diols 20 to 60%, preferably 40 to 50%;

(2) 25-70%, preferably 30-45% of diisocyanate;

(3) 2-10%, preferably 2-5% of small molecule dihydric alcohol with number average molecular weight of 50-800;

(4) bromine-containing chain extenders in the range of 5 to 40%, preferably 10 to 20%;

the percentages are based on the total mass of the raw materials.

The diisocyanate is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, 3 ' -dimethyl-4, 4 ' -biphenyl diisocyanate, cyclohexane dimethylene diisocyanate, 4 ' -dicyclohexylmethane diisocyanate and 3,3 ' -dimethyl-4, 4 ' -diphenylmethane diisocyanate; preferably one or more of toluene diisocyanate, diphenylmethane diisocyanate, 1, 5-naphthalene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, 3 '-dimethyl-4, 4' -biphenyl diisocyanate, and 3,3 '-dimethyl-4, 4' -diphenylmethane diisocyanate.

The linear sulfur-containing diol of the invention has the number average molecular weight of 500-4000g/mol, preferably 800-2000 g/mol.

The linear sulfur-containing diol is formed by reacting diol with dibasic acid. The general structural formula is as follows:

wherein, a and b take the values of 0, 1 or 2, and both cannot be 0 at the same time, preferably 1 or 2, and more preferably 2.

Wherein n is a natural number of 2 to 20, and n is 2,4,6, 8.

Wherein A1 represents a para-phenyl group, a meta-phenyl group or a straight or branched alkyl group having a backbone of 1 to 5 carbon atoms; a2 represents a para-phenyl group, a meta-phenyl group or a straight or branched alkyl group having a backbone of 1 to 5 carbon atoms.

Wherein, the dihydric alcohol commonly used for synthesizing the linear sulfur-containing dihydric alcohol is selected from bis (2-hydroxyethyl) disulfide, 4 '-dihydroxydiphenyl disulfide, 3' -dihydroxydiphenyl disulfide, butanediol, propylene glycol and ethylene glycol.

Wherein, the dibasic acid commonly used for synthesizing the linear sulfur-containing diol is selected from 3,3 '-thiodipropionic acid, 4' -dithiodibutanoic acid, 3 '-dithiodipropionic acid, 4' -dithiodibenzoic acid, 3 '-dicarboxydiphenyl disulfide, 2' -dithiodipropionic acid, succinic acid, adipic acid and azelaic acid.

Among these, the linear sulfur-containing diols can be prepared by methods well known in the art, and can be, for example:

adding the dihydric alcohol and the dibasic acid into a reaction kettle with the capacity of 20L at room temperature according to the molar ratio of 1.2-1.8, adding a titanate catalyst with the total mass fraction of 0.5-1% of the raw materials, introducing nitrogen atmosphere for protection, gradually heating the mixture to 220-240 ℃ under stirring, stirring and reacting for 10-14h at the temperature, removing excessive unreacted dihydric alcohol and generated moisture from the mixture under the vacuum of 300-400 millipascals until the acid value of the mixture is tested to be less than 1mgKOH/g, and collecting the linear sulfur-containing dihydric alcohol with sulfur in the molecular structure for later use.

The number average molecular weight of the micromolecular dihydric alcohol is 50-800, and preferably 50-300.

The small molecular diol is selected from one or more of ethylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, diethylene glycol, 1, 2-propanediol, methyl pentanediol, 1, 4-cyclohexanediol, neopentyl glycol and terephthalyl alcohol; preferably one or more of 1, 3-propanediol, 1, 4-butanediol, 1, 6-hexanediol and neopentyl glycol.

The bromine-containing chain extender is bromine-containing dihydric alcohol, and the number average molecular weight is 100-500, preferably 150-400.

The bromine-containing chain extender is selected from one or more of 2-bromine-1, 3-propylene glycol, 3-bromine-1, 2-propylene glycol, 4-bromine-1, 2-butanediol, 4-bromine-1, 3-butanediol, dibromobutenediol, 1, 4-dibromo-2, 3-butanediol, 2, 3-dibromo-1, 4-butanediol and dibromoneopentyl glycol. Preferably one or more of 4-bromo-1, 3-butanediol, dibromobutenediol, dibromoneopentyl glycol, and 2, 3-dibromo-1, 4-butanediol.

The thermoplastic polyurethane elastomer material has a molar ratio of-NCO functional groups to-OH functional groups in the raw materials of 0.80 to 1.20, preferably 0.98 to 1.02.

The thermoplastic polyurethane elastomer material is prepared by adding a catalyst, wherein the catalyst is selected from one or more of organic tin, organic bismuth, organic lead, organic zinc and organic amine. The addition amount of the catalyst is 0.05-0.1% of the total mass of the raw materials.

According to the test standards of ASTM D1003 and ASTM D542, the thermoplastic polyurethane elastomer material has the light transmittance of more than 88 percent, the refractive index of more than 1.58, preferably the light transmittance of more than 90 percent and the refractive index of more than 1.60.

The preparation method of the thermoplastic polyurethane elastomer adopts a one-step method for continuous production, and comprises the steps of storing the raw materials and the catalyst in a raw material storage tank, controlling the temperature of the storage tank to be 80-120 ℃, metering and mixing the raw materials and the catalyst by a casting machine, feeding the mixture into a double-screw extruder for reaction, controlling the temperature of the extruder to be 140-230 ℃, drying the mixture after extrusion and granulation, and processing the dried thermoplastic polyurethane particles into films or sheets by a casting machine or a calendar.

The thermoplastic polyurethane elastomer material disclosed by the invention is applied to preparing films or sheets, and is particularly used for preparing films or sheets in the fields of automobiles, medical treatment, clothes, electronics and optics.

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

1. the TPU (thermoplastic polyurethane) elastomer material has simple preparation process and easy operation;

2. the TPU material prepared by using the sulfur-containing polyol and simultaneously introducing the bromine-containing chain extender has higher refractive index and transparency, can meet the requirements of the optical field on the material performance, has the refractive index of more than 1.6 and the transparency of more than 90 percent, and has higher commercial application value;

3. the prepared TPU material has excellent processing performance and flame retardant performance to a certain degree.

Detailed Description

The technical solutions of the present invention are further described below by way of specific embodiments, and the present invention is further described in detail by way of specific embodiments, but it should not be construed that the scope of the present invention is limited to the following examples. Various substitutions and alterations can be made by those skilled in the art and by conventional means without departing from the spirit of the above-described method of the invention, and are intended to be included within the scope of the invention:

example 1

A high-refraction high-transparency thermoplastic polyurethane elastomer material is mainly prepared from the following raw materials in parts by weight:

112 parts of diphenylmethane diisocyanate, 80 parts of linear sulfur-containing dihydric alcohol, 8 parts of 1, 4-butanediol, 50 parts of 4-bromo-1, 2-butanediol and 0.25 part of dibutyltin dilaurate.

The linear sulfur-containing diol has the structure:

wherein a is 0, b is 1, and n is 2;

wherein, A1 and A2 have the same structure, and are both

The linear sulfur-containing diol had a number average molecular weight of 554 g/mol.

The above formulation produced a thermoplastic polyurethane R ═ 0.84.

The preparation method of the linear sulfur-containing dihydric alcohol comprises the following steps:

adding butanediol and 3, 3' -thiodipropionic acid into a reaction kettle with the capacity of 20L according to the molar ratio of 1.6 at room temperature, adding tetrabutyl titanate with the total mass fraction of 0.5 percent of the raw materials, introducing nitrogen atmosphere for protection, gradually heating the mixture to 220 ℃ under stirring, stirring and reacting for 11 hours at the temperature, removing excessive unreacted dihydric alcohol and generated moisture from the mixture under the vacuum of 400 millipascals until the acid value of the mixture is tested to be less than 1mgKOH/g, and collecting the prepared linear sulfur-containing dihydric alcohol for later use.

And (2) adopting a one-step method to carry out continuous production, wherein the raw materials and the catalyst are stored in a raw material storage tank at a constant temperature, the temperature of the storage tank is 80 ℃, the raw materials and the catalyst are metered and mixed by a casting machine and are sent into a double-screw extruder to react, the temperature of the extruder is set to be 220 ℃, extruded sample strips are granulated under water and then dried for 16 hours at 80 ℃, and the dried thermoplastic polyurethane particles are processed into films or sheets by a casting machine or a calendar.

The above preparation method is applied to examples 2 to 8 and comparative examples 1 to 2.

Example 2

A high-refraction high-transparency thermoplastic polyurethane elastomer material is mainly prepared from the following raw materials in parts by weight:

95 parts of diphenylmethane diisocyanate, 75 parts of linear sulfur-containing diol, 10 parts of 1, 4-butanediol, 50 parts of dibromoneopentyl glycol and 0.23 part of dibutyltin dilaurate.

The linear sulfur-containing diol has the structure:

wherein, a is 2, n is 3;

wherein, the structures A1 are all

Wherein, A2 has the structure of

The linear sulfur-containing diol had a number average molecular weight of 1222 g/mol.

The above formulation produced a thermoplastic polyurethane theoretical R of 1.05.

The preparation method of the linear sulfur-containing dihydric alcohol comprises the following steps:

adding bis (2-hydroxyethyl) disulfide and 4, 4' -dithiodibutanoic acid into a reaction kettle with the volume of 20L according to the molar ratio of 1.4 at room temperature, adding tetrabutyl titanate with the total mass fraction of 0.5 percent of raw materials, introducing nitrogen atmosphere for protection, gradually heating the mixture to 230 ℃ under stirring, stirring and reacting for 11h at the temperature, removing excessive unreacted dihydric alcohol and generated moisture from the mixture under the vacuum of 400 millipascal until the acid value of the mixture is tested to be less than 1mgKOH/g, and collecting the prepared linear sulfur-containing dihydric alcohol for later use.

The thermoplastic polyurethane elastomer material was prepared in the same manner as in example 1, with an extrusion temperature of 220 ℃.

Example 3

A high-refraction high-transparency thermoplastic polyurethane elastomer material is mainly prepared from the following raw materials in parts by weight:

62 parts of hexamethylene diisocyanate, 100 parts of linear sulfur-containing dihydric alcohol, 9 parts of 1, 4-butanediol, 50 parts of dibromo neopentyl glycol and 0.22 part of dibutyltin dilaurate.

The linear sulfur-containing diol has the structure:

wherein a is 2, b is 0, and n is 4;

wherein, A1 has the structure of

Wherein, A2 has the structure of

The linear sulfur-containing diol had a number average molecular weight of 1210 g/mol.

The above formulation yields a thermoplastic polyurethane theoretical R of 0.99.

The preparation method of the linear sulfur-containing dihydric alcohol comprises the following steps:

adding bis (2-hydroxyethyl) disulfide and adipic acid into a reaction kettle with the capacity of 20L according to the molar ratio of 1.2 at room temperature, adding tetrabutyl titanate with the total mass fraction of 0.5 percent of the raw materials, introducing nitrogen atmosphere for protection, gradually heating the mixture to 220 ℃ under stirring, stirring and reacting for 12 hours at the temperature, removing excessive unreacted dihydric alcohol and generated moisture from the mixture under the vacuum of 400 millipascals until the acid value of the mixture is tested to be less than 1mgKOH/g, and collecting the prepared linear sulfur-containing dihydric alcohol for later use.

The thermoplastic polyurethane elastomer material was prepared in the same manner as in example 1, with an extrusion temperature of 210 ℃.

Example 4

A high-refraction high-transparency thermoplastic polyurethane elastomer material is mainly prepared from the following raw materials in parts by weight:

56 parts of hexamethylene diisocyanate, 125 parts of linear sulfur-containing dihydric alcohol, 8 parts of 1, 4-butanediol, 30 parts of 4-bromo-1, 3-butanediol and 0.22 part of dibutyltin dilaurate.

The linear sulfur-containing diol has the structure:

wherein a is 2, n is 6;

wherein, A1 has the structure of

Wherein, A2 has the structure of

The linear sulfur-containing diol had a number average molecular weight of 2122 g/mol.

The above formulation yields a thermoplastic polyurethane theoretical R of 1.02.

The preparation method of the linear sulfur-containing dihydric alcohol comprises the following steps:

adding bis (2-hydroxyethyl) disulfide and 2, 2' -dithiodipropionic acid into a reaction kettle with the volume of 20L according to the molar ratio of 1.2 at room temperature, adding tetrabutyl titanate with the mass fraction of 0.5 percent of the total mass fraction of the raw materials, introducing nitrogen atmosphere for protection, gradually heating the mixture to 230 ℃ under stirring, stirring and reacting for 12 hours at the temperature, removing excessive unreacted dihydric alcohol and generated moisture from the mixture under the vacuum of 400 millipascals until the acid value of the mixture is tested to be less than 1mgKOH/g, and collecting the prepared linear sulfur-containing dihydric alcohol for later use.

The thermoplastic polyurethane elastomer material was prepared in the same manner as in example 1, with an extrusion temperature of 190 ℃.

Example 5

A high-refraction high-transparency thermoplastic polyurethane elastomer material is mainly prepared from the following raw materials in parts by weight:

69 parts of diphenylmethane diisocyanate, 125 parts of linear sulfur-containing diol, 9 parts of 1, 4-butanediol, 36 parts of dibromobutylene glycol and 0.24 part of dibutyltin dilaurate.

The linear sulfur-containing diol has the structure:

wherein a is 2, n is 8

Wherein, A1 has the structure of

Wherein, A2 has the structure of

The linear sulfur-containing diol had a number average molecular weight of 3546 g/mol.

The above formulation produced a thermoplastic polyurethane theoretical R of 0.98.

The preparation method of the linear sulfur-containing dihydric alcohol comprises the following steps:

adding bis (2-hydroxyethyl) disulfide and 4, 4' -dithiodibenzoic acid into a reaction kettle with the capacity of 20L according to the molar ratio of 1.2 at room temperature, adding tetrabutyl titanate with the mass fraction of 0.5 percent of the total mass fraction of raw materials, introducing nitrogen atmosphere for protection, gradually heating the mixture to 240 ℃ under stirring, stirring and reacting for 13 hours at the temperature, removing excessive unreacted dihydric alcohol and generated moisture from the mixture under the vacuum of 400 millipascals until the acid value of the mixture is tested to be less than 1mgKOH/g, and collecting the prepared linear sulfur-containing dihydric alcohol for later use.

The thermoplastic polyurethane elastomer material was prepared in the same manner as in example 1, with an extrusion temperature of 205 ℃.

Example 6

A high-refraction high-transparency thermoplastic polyurethane elastomer material is mainly prepared from the following raw materials in parts by weight:

78 parts of diphenylmethane diisocyanate, 125 parts of linear sulfur-containing dihydric alcohol, 9 parts of 1, 4-butanediol, 36 parts of 2, 3-dibromo-1, 4-butanediol and 0.25 part of dibutyltin dilaurate.

The linear sulfur-containing diol has the structure:

wherein a is 2, n is 4;

wherein, A1 has the structure of

Wherein, A2 has the structure of

The linear sulfur-containing diol had a number average molecular weight of 2058 g/mol.

The above formulation yields a thermoplastic polyurethane theoretical R of 1.02.

The preparation method of the linear sulfur-containing dihydric alcohol comprises the following steps:

adding 4,4 '-dihydroxydiphenyl disulfide and 4, 4' -dithiodibutanoic acid into a reaction kettle with the volume of 20L according to the molar ratio of 1.3 at room temperature, adding tetrabutyl titanate with the mass fraction of 0.5 percent of the total mass fraction of raw materials, introducing nitrogen atmosphere for protection, gradually heating the mixture to 240 ℃ under stirring, stirring and reacting for 13h at the temperature, removing excessive unreacted dihydric alcohol and generated moisture from the mixture under the vacuum of 400 millipascal until the acid value of the mixture is tested to be less than 1mgKOH/g, and collecting the prepared linear sulfur-containing dihydric alcohol for later use.

The thermoplastic polyurethane elastomer material was prepared in the same manner as in example 1, with an extrusion temperature of 210 ℃.

Example 7

A high-refraction high-transparency thermoplastic polyurethane elastomer material is mainly prepared from the following raw materials in parts by weight:

69 parts of diphenylmethane diisocyanate, 125 parts of linear sulfur-containing diol, 9 parts of 1, 4-butanediol, 37 parts of dibromoneopentyl glycol and 0.24 part of dibutyltin dilaurate.

The linear sulfur-containing diol has the structure:

wherein a is 2, n is 7;

wherein, A1 has the structure of

Wherein, A2 has the structure of

The linear sulfur-containing diol had a number average molecular weight of 3890 g/mol.

The above formulation yields a thermoplastic polyurethane theoretical R of 1.01.

The preparation method of the linear sulfur-containing dihydric alcohol comprises the following steps:

adding 4,4 '-dihydroxydiphenyl disulfide and 4, 4' -dithiodibenzoic acid into a reaction kettle with the capacity of 20L according to the molar ratio of 1.2 at room temperature, adding tetrabutyl titanate with the mass fraction of 0.5 percent of the total mass fraction of raw materials, introducing nitrogen atmosphere for protection, gradually heating the mixture to 240 ℃ under stirring, stirring and reacting for 14h at the temperature, removing excessive unreacted dihydric alcohol and generated moisture from the mixture under the vacuum of 400 millipascals until the acid value of the mixture is tested to be less than 1mgKOH/g, and collecting the prepared linear sulfur-containing dihydric alcohol for later use.

The thermoplastic polyurethane elastomer material was prepared in the same manner as in example 1, with an extrusion temperature of 205 ℃.

Example 8

A high-refraction high-transparency thermoplastic polyurethane elastomer material is mainly prepared from the following raw materials in parts by weight:

82 parts of diphenylmethane diisocyanate, 150 parts of linear sulfur-containing dihydric alcohol, 7 parts of 1, 4-butanediol, 30 parts of 4-bromo-1, 3-butanediol and 0.27 part of dibutyltin dilaurate.

The linear sulfur-containing diol has the structure:

wherein a is 2, n is 4;

wherein, A1 has the structure of

Wherein, A2 has the structure of

The linear sulfur-containing diol had a number average molecular weight of 2058 g/mol.

The above formulation yields a thermoplastic polyurethane theoretical R of 1.00.

The preparation method of the linear sulfur-containing dihydric alcohol comprises the following steps:

adding 3,3 '-dihydroxydiphenyl disulfide and 4, 4' -dithiodibutanoic acid into a reaction kettle with the volume of 20L according to the molar ratio of 1.3 at room temperature, adding tetrabutyl titanate with the mass fraction of 0.5 percent of the total mass fraction of raw materials, introducing nitrogen atmosphere for protection, gradually heating the mixture to 240 ℃ under stirring, stirring and reacting for 13h at the temperature, removing excessive unreacted dihydric alcohol and generated moisture from the mixture under the vacuum of 400 millipascal until the acid value of the mixture is tested to be less than 1mgKOH/g, and collecting the prepared linear sulfur-containing dihydric alcohol for later use.

The thermoplastic polyurethane elastomer material was prepared in the same manner as in example 1, with an extrusion temperature of 195 ℃.

Comparative example 1

95 parts of diphenylmethane diisocyanate, 75 parts of polybutylene adipate glycol, 10 parts of 1, 4-butanediol, 50 parts of dibromo neopentyl glycol and 0.23 part of dibutyltin dilaurate.

The polybutylene adipate diol has a number average molecular weight of 1222 g/mol.

The above formulation produced a thermoplastic polyurethane theoretical R of 1.05.

The thermoplastic polyurethane elastomer material was prepared in the same manner as in example 1, with an extrusion temperature of 220 ℃.

Comparative example 2

72 parts of diphenylmethane diisocyanate, 125 parts of polybutylene adipate glycol, 20 parts of 1, 4-butanediol and 0.22 part of dibutyltin dilaurate.

The polybutylene adipate glycol number average molecular weight was 2122 g/mol.

The above formulation yields a thermoplastic polyurethane theoretical R of 1.02.

The thermoplastic polyurethane elastomer material was prepared in the same manner as in example 1, with an extrusion temperature of 190 ℃.

TABLE 1 raw material tables for examples and comparative examples

The prepared examples and comparative examples were tested for light transmittance, haze and refractive index according to ASTM D1003 and ASTM D542 test standards.

Transparency and haze: a 2.0mm sample piece prepared by an injection molding process was tested using a TTRAN type haze meter manufactured by HUTER LAB corporation;

refractive index: a2.0 mm sample prepared by injection molding was tested using an Abbe refractometer model DR-M2, manufactured by ATAGO.

The test results for each example and comparative example are shown in the following table:

TABLE 2 table of results of performance test of examples and comparative examples

	Light transmittance	Haze degree	Refractive index
				Example 1	90.2	2.3	1.633
Example 2	90.2	2.4	1.635
				Example 3	91.4	2.2	1.643
Example 4	91.6	2.1	1.651
				Example 5	90.5	2.5	1.646
Example 6	90.1	2.4	1.642
				Example 7	89.8	2.5	1.641
Example 8	90.3	2.2	1.638
				Comparative example 1	89.1	2.6	1.521
Comparative example 2	88.1	2.9	1.495