阅读说明：本技术 一种利用化学法循环再生纤维生产后的副产品制造改性工程聚酯的方法 (Method for preparing modified engineering polyester by using byproducts generated after chemical method cyclic regeneration of fiber vitamins ) 是由 尹乐家 舒宏大 张炜良 官军 于 2021-09-08 设计创作，主要内容包括：本发明公开了一种利用化学法循环再生纤维生产后的副产品制造改性工程聚酯的方法,包括以下步骤：以化学法循环再生纤维生产后的乙二醇副产品、催化剂、金属螯合剂为原料,加入或不加入交联剂和/或苯甲酸副产物,进行酯化反应,并在反应过程中馏出水和乙二醇；酯化结束后升温并在真空条件下进行聚合反应,同时馏出乙二醇,待反应一段时间后破真空并停止加热,加入或不加入改性剂,保温至聚合反应结束,经出料、冷却、结晶,得到聚酯产品。本发明成功将原本废弃的乙二醇副产品转化成各种聚酯产品,实现了废弃物的100％再利用,避免了环境污染,而且能够为化学法循环再生纤维的生产提供原料,降低生产成本。(The invention discloses a method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fibers, which comprises the following steps: ethylene glycol by-products after the chemical method recycling of the regenerated cellulose, catalysts and metal chelating agents are used as raw materials, a cross-linking agent and/or benzoic acid by-products are added or not added, esterification reaction is carried out, and water and ethylene glycol are distilled off in the reaction process; after the esterification is finished, heating and carrying out polymerization reaction under a vacuum condition, distilling off ethylene glycol, breaking vacuum and stopping heating after the reaction is carried out for a period of time, adding or not adding a modifier, keeping the temperature until the polymerization reaction is finished, discharging, cooling and crystallizing to obtain the polyester product. The method successfully converts the originally waste ethylene glycol byproduct into various polyester products, realizes 100 percent reutilization of waste, avoids environmental pollution, can provide raw materials for the production of the chemical method recycled fiber, and reduces the production cost.)

1. A method for preparing modified engineering polyester by using byproducts generated after chemical method cyclic regeneration of fiber vitamins is characterized in that: ethylene glycol by-products after the chemical method recycling of the regenerated cellulose, catalysts and metal chelating agents are used as raw materials, a cross-linking agent and/or benzoic acid by-products are added or not added, esterification reaction is carried out, and water and ethylene glycol are distilled off in the reaction process; after the esterification is finished, heating and carrying out polymerization reaction under a vacuum condition, distilling off ethylene glycol, breaking vacuum and stopping heating after the reaction is carried out for a period of time, adding or not adding a modifier, keeping the temperature until the polymerization reaction is finished, discharging, cooling and crystallizing to obtain the polyester product.

2. The method of claim 1, wherein the modified engineering polyester is prepared by recycling byproducts from regenerated fiber production by chemical methods, and the method comprises the following steps: the method specifically comprises the following steps:

(a) adding ethylene glycol byproduct, catalyst and metal chelating agent into a polymerization reaction kettle, adding or not adding cross-linking agent and/or benzoic acid byproduct, stirring and heating to 160-165 ℃ for esterification reaction, and successively cutting 120 ℃ front fraction and 120 ℃ above fraction;

(b) continuously stirring and heating to 230 ℃ and 245 ℃, vacuumizing, carrying out polymerization reaction, and cutting ethylene glycol fraction through a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, adding or not adding a modifier, keeping the temperature at 190 ℃ at 180 ℃ until the polymerization reaction is finished, and obtaining the polyester product through discharging, cooling and crystallizing treatment.

3. The method for producing modified engineering polyester according to claim 1 or 2, wherein the by-product of the chemical recycling of regenerated fiber is produced by the method comprising: the mass ratio of the ethylene glycol byproduct to the catalyst to the metal chelating agent is 700: (10-35): (42-49); when only the cross-linking agent is added, the mass ratio of the ethylene glycol byproduct to the cross-linking agent is 70: (7-10), when only the benzoic acid by-product is added, the mass ratio of the ethylene glycol by-product to the benzoic acid by-product is 1: (3-3.5), when the cross-linking agent and the benzoic acid byproduct are added simultaneously, the mass ratio of the ethylene glycol byproduct to the cross-linking agent to the benzoic acid byproduct is 700: (70-100): (210-245).

4. The method for producing modified engineering polyester according to claim 1 or 2, wherein the by-product of the chemical recycling of regenerated fiber is produced by the method comprising: the ethylene glycol byproduct comprises, by mass, 29.1-30.2% of EG, 8.6-9.3% of DEG, 16.3-17.5% of BHET monomer, 41.5-43.4% of BHET with the polymerization degree of 2-6, 2.2-3% of potassium carbonate and the balance of water.

5. The method for producing modified engineering polyester according to claim 1 or 2, wherein the by-product of the chemical recycling of regenerated fiber is produced by the method comprising: the catalyst is sulfuric acid.

6. The method for producing modified engineering polyester according to claim 1 or 2, wherein the by-product of the chemical recycling of regenerated fiber is produced by the method comprising: the metal chelating agent is one or more of potassium salt chelating agents.

7. The method for producing modified engineering polyester according to claim 1 or 2, wherein the by-product of the chemical recycling of regenerated fiber is produced by the method comprising: the benzoic acid by-product comprises 15-23% of phthalic acid, 75-82% of methyl benzoic acid and 1-3% of benzoic acid in percentage by mass.

8. The method for producing modified engineering polyester according to claim 1 or 2, wherein the by-product of the chemical recycling of regenerated fiber is produced by the method comprising: the esterification reaction time is 3.5-4 h; the polymerization reaction time is 4.5-5 h.

9. The method for producing modified engineering polyester according to claim 1 or 2, wherein the by-product of the chemical recycling of regenerated fiber is produced by the method comprising: when the modifier is added, the mass ratio of the ethylene glycol byproduct to the modifier is 70 (15-18).

10. The method for producing modified engineering polyester according to claim 1 or 2, wherein the by-product of the chemical recycling of regenerated fiber is produced by the method comprising: the modifier is selected from at least one of polybasic acid, polyalcohol and phenolic resin.

Technical Field

The invention relates to the technical field of high polymer materials, in particular to a method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fibers.

Background

The polyester recycling method comprises a physical regeneration method and a chemical regeneration method, wherein the chemical regeneration method comprises the steps of separating and crushing waste polyester materials, depolymerizing the waste polyester materials under certain chemical conditions to generate low-molecular-weight compounds or ester monomers, refining the low-molecular-weight compounds or ester monomers, and repolymerizing the low-molecular-weight compounds or ester monomers to produce polyester fibers. The currently commonly used depolymerization methods of waste polyester materials include a hydrolysis method, a methanol depolymerization method, an ethylene glycol depolymerization method and an alcohol-base combined depolymerization method, wherein the ethylene glycol depolymerization method has the advantages of milder degradation conditions and higher recovery rate compared with the hydrolysis method and the methanol alcoholysis method, and becomes the mainstream chemical recovery method at present. After the ethylene glycol depolymerization process is used to produce recycled polyester fibers, a large amount of ethylene glycol by-products remain, and the ethylene glycol by-products have complex components and high viscosity, especially the residual potassium carbonate substances have an end-capping effect on the polymerization reaction, so that the ethylene glycol by-products are difficult to recycle.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fibers, which successfully converts the originally waste ethylene glycol byproducts into various polyester products, realizes 100% recycling of wastes, avoids environmental pollution, can provide raw materials for production of chemical recycling of regenerated fibers and reduces production cost.

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

a method for preparing modified engineering polyester by using byproducts generated after chemical method recycling of regenerated fiber vitamins comprises the steps of taking ethylene glycol byproducts, catalysts and metal chelating agents generated after chemical method recycling of regenerated fiber vitamins as raw materials, adding or not adding a cross-linking agent and/or benzoic acid byproducts, carrying out esterification reaction, and distilling off water and ethylene glycol in the reaction process; after the esterification is finished, heating and carrying out polymerization reaction under a vacuum condition, distilling off ethylene glycol, breaking vacuum and stopping heating after the reaction is carried out for a period of time, adding or not adding a modifier, keeping the temperature until the polymerization reaction is finished, discharging, cooling and crystallizing to obtain the polyester product.

The method specifically comprises the following steps:

(a) adding ethylene glycol byproduct, catalyst and metal chelating agent into a polymerization reaction kettle, adding or not adding cross-linking agent and/or benzoic acid byproduct, stirring and heating to 160-165 ℃ for esterification reaction, and successively cutting 120 ℃ front fraction and 120 ℃ above fraction;

(b) continuously stirring and heating to 230 ℃ and 245 ℃, vacuumizing, carrying out polymerization reaction, and cutting ethylene glycol fraction through a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, adding or not adding a modifier, keeping the temperature at 190 ℃ at 180 ℃ until the polymerization reaction is finished, and obtaining the polyester product through discharging, cooling and crystallizing treatment.

The mass ratio of the ethylene glycol byproduct to the catalyst to the metal chelating agent is 700: (10-35): (42-49); when only the cross-linking agent is added, the mass ratio of the ethylene glycol byproduct to the cross-linking agent is 70: (7-10), when only the benzoic acid by-product is added, the mass ratio of the ethylene glycol by-product to the benzoic acid by-product is 1: (3-3.5), when the cross-linking agent and the benzoic acid byproduct are added simultaneously, the mass ratio of the ethylene glycol byproduct to the cross-linking agent to the benzoic acid byproduct is 700: (70-100): (210-245).

The ethylene glycol byproduct comprises, by mass, 29.1-30.2% of EG, 8.6-9.3% of DEG, 16.3-17.5% of BHET monomer, 41.5-43.4% of BHET with the polymerization degree of 2-6, 2.2-3% of potassium carbonate and the balance of water.

The catalyst is sulfuric acid, preferably concentrated sulfuric acid with the concentration of 70-98.3 wt%.

The metal chelating agent is one or more of potassium salt chelating agents.

The benzoic acid by-product comprises 15-23% of phthalic acid, 75-82% of methyl benzoic acid and 1-3% of benzoic acid in percentage by mass.

The esterification reaction time is 3.5-4 h; the polymerization reaction time is 4.5-5 h.

When the modifier is added, the mass ratio of the ethylene glycol byproduct to the modifier is 70: (15-18).

The modifier is selected from at least one of polybasic acid, polyalcohol and phenolic resin. The polybasic acids include fumaric acid, 1, 4-cyclohexanedicarboxylic acid, hexahydrophthalic acid, adipic acid, etc.; the polyhydric alcohol includes polyethylene glycol, polypropylene glycol, pentaerythritol, 1, 6-hexanediol, glycerol, neopentyl glycol, trimethylolethane, 3-methyl-1, 5-pentanediol, 1, 4-butanediol, etc.; the phenolic resin includes phenolic resin 2123 and the like.

The invention has the beneficial effects that: the potassium carbonate substance in the ethylene glycol byproduct plays a role in end capping in the production process of the recycled fiber by a chemical method, and the generated ethylene glycol byproduct cannot be recycled at present due to the existence of the potassium carbonate and the high viscosity of the ethylene glycol byproduct; the invention removes the end capping effect of potassium carbonate through the innovative design of the process, particularly the introduction of a catalyst and a chelating agent, so that the esterification reaction is smoothly carried out, and can also prepare a polyester resin product which has the performance meeting the standard and is suitable for the fields of waterproofing agents, coatings, paints, adhesives and engineering resins through the introduction of a cross-linking agent and/or a benzoic acid byproduct and/or a modifying agent, thereby overcoming the technical difficulty that ethylene glycol byproducts are difficult to recycle, realizing 100 percent recycle of wastes (ethylene glycol byproducts), and avoiding environmental pollution; and in the preparation process, redundant ethylene glycol and water are rectified and recovered, so that the esterification and polymerization reactions are efficiently carried out, raw materials can be provided for the production of the chemical method recycled fiber, and the production cost is effectively reduced.

Drawings

FIG. 1 is a first perspective view structural view of a polymerization reactor of the present invention;

FIG. 2 is an enlarged view taken at A in FIG. 1;

FIG. 3 is a cross-sectional view taken along line B-B of FIG. 1;

FIG. 4 is a view showing a second perspective of a polymerization reactor of the present invention;

fig. 5 is an enlarged view at C in fig. 4.

In the figure: the device comprises a kettle body 1, a partition plate 11, a slide rail 111, a rotary disc 12, a slide groove 121, a motor 13, a first support 14, a second support 15, a guide shaft 2, a first stirring paddle 3, a driving cam 4, a ring sleeve part 41, a ring part 42, a semi-elliptic arc ring 421, a connecting part 43, a scraping part 5, a connecting shaft 51, a scraping plate 52, a push rod 6, a groove part 61, a rod part 62, a guide pillar 63, a connecting rod 7, a second stirring paddle 8, a rack-and-pinion structure 9, a rack 91 and a gear 92.

Detailed Description

The invention is further described with reference to the accompanying drawings and the detailed description below:

example 1

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol byproduct, catalyst and metal chelating agent according to the mass ratio of 700: 10: 44, adding the mixture into a polymerization reaction kettle, stirring and heating the mixture to 160 ℃ to perform esterification reaction for 3.5 hours, and successively cutting a front fraction at 120 ℃ and a fraction above 120 ℃;

the ethylene glycol byproduct comprises, by mass percent, 29.6% of EG, 9% of DEG, 17.3% of BHET monomer, 41.7% of BHET with the polymerization degree of 2-6, 2.2% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents;

(b) continuously stirring and heating to 230 ℃, vacuumizing, carrying out polymerization reaction, and cutting ethylene glycol fraction by a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, keeping the temperature at 180 ℃ until the polymerization reaction is finished, wherein the polymerization reaction time is 4.5h, and obtaining the polyester product through discharging, cooling and crystallizing treatment. The softening point of the polyester product was determined to be 110 ℃.

Comparative example

A polyester product was prepared according to the method of example 1, except that: hydrochloric acid, sulfuric acid, etc. are used as catalysts, respectively. As shown in Table 1, it can be understood from Table 1 that the activity of hydrochloric acid, nitric acid, oxalic acid, glutaric acid, etc., which are catalysts, is deactivated over several minutes, and sulfuric acid, which is a catalyst, shows uniqueness in the preparation of polyester products according to the present invention.

TABLE 1

	Catalyst type	Rate of deactivation	Yield of
				Example 1	98.3% concentrated sulfuric acid	Without deactivation	97.5
Comparative example 1	85.7% concentrated sulfuric acid	Without deactivation	96.1
				Comparative example 2	70% concentrated sulfuric acid	Without deactivation	90.2
Comparative example 3	40% sulfuric acid	Without deactivation	83.4
				Comparative example 4	10% sulfuric acid	Without deactivation	78.7
Comparative example 5	Hydrochloric acid	Deactivation of the enzyme	-
				Comparative example 6	Nitric acid	Deactivation of the enzyme	-
Comparative example 7	Oxalic acid	Deactivation of the enzyme	-
				Comparative example 8	Glutaric acid	Deactivation of the enzyme	-

Example 2

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol byproduct, catalyst and metal chelating agent according to the mass ratio of 700: 10: 47 is added into a polymerization reaction kettle, stirred and heated to 165 ℃ for esterification reaction for 4 hours, and the front fraction at 120 ℃ and the fractions above 120 ℃ are cut in sequence;

the ethylene glycol byproduct comprises, by mass, 29.1% of EG, 9% of DEG, 16.5% of BHET monomer, 42.1% of BHET with the polymerization degree of 2-6, 3% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents;

(b) continuously stirring and heating to 245 ℃, vacuumizing, carrying out polymerization reaction, and cutting ethylene glycol fraction by a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, keeping the temperature at 190 ℃ until the polymerization reaction is finished, wherein the polymerization reaction time is 4.5h, and discharging, cooling and crystallizing to obtain the polyester product. The softening point of the polyester product was determined to be 112 ℃.

Example 3

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol byproduct, catalyst and metal chelating agent according to the mass ratio of 700: 15: 42, adding the mixture into a polymerization reaction kettle, stirring and heating the mixture to 165 ℃ for esterification reaction for 3.5 hours, and successively cutting a front fraction at 120 ℃ and a fraction above 120 ℃;

the ethylene glycol byproduct comprises, by mass percent, 29.7% of EG, 8.8% of DEG, 17.1% of BHET monomer, 41.8% of BHET with the polymerization degree of 2-6, 2.3% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents;

(b) continuously stirring and heating to 235 ℃, vacuumizing, carrying out polymerization reaction for 4.5h, and cutting ethylene glycol fraction through a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, keeping the temperature at 190 ℃ until the polymerization reaction is finished, wherein the polymerization reaction time is 5h, and discharging, cooling and crystallizing to obtain the polyester product. The softening point of the polyester product was determined to be 113 ℃.

Example 4

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol byproduct, catalyst and metal chelating agent according to the mass ratio of 700: 18: 49: 85: adding into a polymerization reaction kettle, stirring, heating to 160 deg.C, performing esterification reaction for 3.5h, and sequentially cutting 120 deg.C front fraction and above 120 deg.C fraction;

the ethylene glycol byproduct comprises, by mass percent, 29.5% of EG, 8.9% of DEG, 17.5% of BHET monomer, 41.6% of BHET with the polymerization degree of 2-6, 2.3% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents;

(b) continuously stirring and heating to 240 ℃, vacuumizing, carrying out polymerization reaction, and cutting ethylene glycol fraction through a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, keeping the temperature at 185 ℃ until the polymerization reaction is finished, wherein the polymerization reaction time is 5h, and discharging, cooling and crystallizing to obtain the polyester product. The softening point of the polyester product was determined to be 112.5 ℃.

Example 5

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol by-product, catalyst, metal chelating agent and cross-linking agent according to the mass ratio of 700: 10: 44: 70 adding into a polymerization reaction kettle, stirring and heating to 160 ℃ for esterification reaction for 3.5h, and successively cutting 120 ℃ front fraction and 120 ℃ above fraction;

the ethylene glycol byproduct comprises, by mass percent, 29.6% of EG, 9% of DEG, 17.3% of BHET monomer, 41.7% of BHET with the polymerization degree of 2-6, 2.2% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents;

(b) continuously stirring and heating to 230 ℃, vacuumizing, carrying out polymerization reaction, and cutting ethylene glycol fraction by a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, keeping the temperature at 180 ℃ until the polymerization reaction is finished, wherein the polymerization reaction time is 5h, discharging, cooling and crystallizing to obtain the polyester product. The softening point of the polyester product is 110.8 ℃, the breaking strength is 95MPa, and the notch impact strength reaches 7.2MPa, so that the polyester product can be used as engineering resin.

Example 6

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol by-product, catalyst, metal chelating agent and cross-linking agent according to the mass ratio of 700: 35: 45: 100, adding the mixture into a polymerization reaction kettle, stirring and heating to 165 ℃ for esterification reaction for 4 hours, and successively cutting a front fraction at 120 ℃ and a fraction above 120 ℃;

the ethylene glycol byproduct comprises, by mass, 29.1% of EG, 9% of DEG, 16.5% of BHET monomer, 42.1% of BHET with the polymerization degree of 2-6, 3% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents;

(b) continuously stirring and heating to 245 ℃, vacuumizing, carrying out polymerization reaction, and cutting ethylene glycol fraction by a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, keeping the temperature at 190 ℃ until the polymerization reaction is finished, wherein the polymerization reaction time is 5h, discharging, cooling and crystallizing to obtain the polyester product. The polyester product has a softening point of 112 ℃, a breaking strength of 116MPa and a notch impact strength of 8.4MPa, and can be used as engineering resin.

Example 7

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol byproduct, catalyst, metal chelating agent and benzoic acid byproduct according to the mass ratio of 700: 13: 42: 2100 is added into a polymerization reaction kettle, stirred and heated to 165 ℃ for esterification reaction for 3.5h, and pre-fraction of 120 ℃ and fraction above 120 ℃ are cut in sequence;

the ethylene glycol byproduct comprises, by mass percent, 29.7% of EG, 8.8% of DEG, 17.1% of BHET monomer, 41.8% of BHET with the polymerization degree of 2-6, 2.3% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents; the benzoic acid by-product comprises 15% of phthalic acid, 82% of methyl benzoic acid and 3% of benzoic acid in percentage by mass;

(b) continuously stirring and heating to 235 ℃, vacuumizing, carrying out polymerization reaction, and cutting ethylene glycol fraction by a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, keeping the temperature at 190 ℃ until the polymerization reaction is finished, wherein the polymerization reaction time is 5h, discharging, cooling and crystallizing to obtain the polyester product. The softening point of the polyester product is 111.3 ℃, the breaking strength is 110MPa, and the notch impact strength reaches 8.1 MPa.

Example 8

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol byproduct, catalyst, metal chelating agent and benzoic acid byproduct according to the mass ratio of 700: 28: 49: 245 into a polymerization reaction kettle, stirring and heating to 160 ℃ for esterification reaction for 4 hours, and successively cutting a front fraction at 120 ℃ and a fraction above 120 ℃;

the ethylene glycol byproduct comprises, by mass percent, 29.7% of EG, 8.8% of DEG, 17.1% of BHET monomer, 41.8% of BHET with the polymerization degree of 2-6, 2.3% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents; the benzoic acid by-product comprises 23% of phthalic acid, 75% of methyl benzoic acid and 2% of benzoic acid in percentage by mass;

(b) continuously stirring and heating to 235 ℃, vacuumizing, carrying out polymerization reaction, and cutting ethylene glycol fraction by a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, keeping the temperature at 190 ℃ until the polymerization reaction is finished, wherein the polymerization reaction time is 5h, discharging, cooling and crystallizing to obtain the polyester product. The polyester product has a softening point of 115 ℃, a breaking strength of 117MPa and a notch impact strength of 8.5 MPa.

Example 9

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol byproduct, catalyst and metal chelating agent according to the mass ratio of 700: 18: 44, adding the mixture into a polymerization reaction kettle, stirring and heating the mixture to 160 ℃ to perform esterification reaction for 4 hours, and successively cutting 120 ℃ front fraction and 120 ℃ above fraction;

the ethylene glycol byproduct comprises, by mass percent, 29.5% of EG, 8.9% of DEG, 17.5% of BHET monomer, 41.6% of BHET with the polymerization degree of 2-6, 2.3% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents;

(b) continuously stirring and heating to 245 ℃, vacuumizing, carrying out polymerization reaction for 5 hours at 245 ℃, and cutting ethylene glycol fraction through a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, adding a phenolic resin 2123 modifier (the mass ratio of the ethylene glycol byproduct to the phenolic resin 2123 is 700: 150), keeping the temperature at 180 ℃ until the polymerization reaction is finished, keeping the polymerization reaction time for 5h, discharging, cooling and crystallizing to obtain a phenolic resin modified polyester product. The softening point of the polyester product is 118 ℃, the breaking strength is 119MPa, and the notch impact strength reaches 8.7 MPa.

Example 10

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol byproduct, catalyst and metal chelating agent according to the mass ratio of 700: 20: 42, adding the mixture into a polymerization reaction kettle, stirring and heating the mixture to 160 ℃ to perform esterification reaction for 4 hours, and successively cutting 120 ℃ front fraction and 120 ℃ above fraction;

the ethylene glycol byproduct comprises, by mass percent, 29.5% of EG, 8.9% of DEG, 17.5% of BHET monomer, 41.6% of BHET with the polymerization degree of 2-6, 2.3% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents;

(b) continuously stirring and heating to 245 ℃, vacuumizing, carrying out polymerization reaction for 5 hours at 245 ℃, and cutting ethylene glycol fraction through a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, adding a phenolic resin 2123 modifier (the mass ratio of the ethylene glycol byproduct to the phenolic resin 2123 is 700:180), keeping the temperature at 190 ℃ until the polymerization reaction is finished, keeping the polymerization reaction time at 5h, discharging, cooling and crystallizing to obtain a phenolic resin modified polyester product. The softening point of the polyester product is 120 ℃, the breaking strength is 120MPa, and the notch impact strength reaches 8.7 MPa.

Example 11

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol by-product, catalyst, metal chelating agent and cross-linking agent according to the mass ratio of 700: 12: 45: 90, adding the mixture into a polymerization reaction kettle, stirring and heating the mixture to 160 ℃ to perform esterification reaction for 4 hours, and successively cutting a front fraction at 120 ℃ and a fraction above 120 ℃;

the ethylene glycol byproduct comprises, by mass percent, 30.2% of EG, 8.7% of DEG, 17% of BHET monomer, 41.5% of BHET with the polymerization degree of 2-6, 2.4% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents;

(b) continuously stirring and heating to 230 ℃, vacuumizing, carrying out polymerization reaction, and cutting ethylene glycol fraction by a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, adding a polyethylene glycol modifier (the mass ratio of the ethylene glycol byproduct to the mixed modifier is 700: 160, and the mass ratio of adipic acid to trimethylolethane is 1:1.5), keeping the temperature at 190 ℃ until the polymerization reaction is finished, wherein the polymerization reaction time is 5 hours, and discharging, cooling and crystallizing to obtain the polyester product for the coating.

Example 12

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol by-product, catalyst, metal chelating agent and cross-linking agent according to the mass ratio of 700: 12: 45: 90, adding the mixture into a polymerization reaction kettle, stirring and heating the mixture to 160 ℃ to perform esterification reaction for 4 hours, and successively cutting a front fraction at 120 ℃ and a fraction above 120 ℃;

the ethylene glycol byproduct comprises, by mass percent, 30.2% of EG, 8.7% of DEG, 17% of BHET monomer, 41.5% of BHET with the polymerization degree of 2-6, 2.4% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents;

(b) continuously stirring and heating to 230 ℃, vacuumizing, carrying out polymerization reaction, and cutting ethylene glycol fraction by a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, adding a mixed modifier of adipic acid and trimethylolethane (the mass ratio of the ethylene glycol byproduct to the mixed modifier is 700: 160, and the mass ratio of the adipic acid to the trimethylolethane is 1:1.5), keeping the temperature at 190 ℃ until the polymerization reaction is finished, wherein the polymerization reaction time is 5 hours, and discharging, cooling and crystallizing to obtain the polyester product for the coating.

Example 13

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol byproduct, catalyst, metal chelating agent and benzoic acid byproduct according to the mass ratio of 700: 13: 43: 2150 adding into polymerization reactor, stirring, heating to 160 deg.C, esterifying for 3.5h, and sequentially cutting 120 deg.C front fraction and 120 deg.C above fraction;

the ethylene glycol byproduct comprises, by mass percent, 29.1% of EG, 8.6% of DEG, 16.4% of BHET monomer, 43.4% of BHET with the polymerization degree of 2-6, 2.2% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents; the benzoic acid by-product comprises 16 percent of phthalic acid, 82 percent of methyl benzoic acid and 2 percent of benzoic acid by mass percentage;

(b) continuously stirring and heating to 230 ℃, vacuumizing, carrying out polymerization reaction at 245 ℃, and cutting ethylene glycol fraction by a rectifying tower; when the temperature of the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, adding a mixed modifier of trimethylolethane and 1, 4-cyclohexanedicarboxylic acid (the mass ratio of the ethylene glycol byproduct to the mixed modifier is 700: 167, and the mass ratio of the mixture of trimethylolethane and 1, 4-cyclohexanedicarboxylic acid is 1:1.2), preserving the temperature at 180 ℃ until the polymerization reaction is finished, discharging, cooling and crystallizing to obtain the polyester product for the adhesive. The intrinsic viscosity i.v. of the polyester product for adhesives was determined to be 0.32.

Example 14

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) ethylene glycol byproduct, catalyst, metal chelating agent, cross-linking agent and benzoic acid byproduct are mixed according to the mass ratio of 700: 10.5: 46: 80: 2100 is added into a polymerization reaction kettle, stirred and heated to 160 ℃ for esterification reaction for 3.5h, and the front fraction at 120 ℃ and the fractions above 120 ℃ are cut in sequence;

the ethylene glycol byproduct comprises, by mass, 30% of EG, 8.6% of DEG, 16.3% of BHET monomer, 42% of BHET with the polymerization degree of 2-6, 2.8% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents; the benzoic acid by-product comprises 17% of phthalic acid, 81% of methyl benzoic acid and 2% of benzoic acid in percentage by mass;

(b) continuously stirring and heating to 230 ℃, vacuumizing, carrying out polymerization reaction for 4.5h at 230 ℃, and cutting ethylene glycol fraction through a rectifying tower; when the temperature at the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, adding a mixed modifier of hexahydrophthalic acid, neopentyl glycol and 3-methyl-1, 5-pentanediol (the mass ratio of an ethylene glycol byproduct to the mixed modifier is 700: 175, and the mol ratio of the hexahydrophthalic acid, the neopentyl glycol and the 3-methyl-1, 5-pentanediol is 1: 1: 0.5), preserving the temperature at 180 ℃ until the polymerization reaction is finished, discharging, cooling and crystallizing to obtain the polyester product for the paint. The viscosity of the modified polyester for paint was determined to be 930 mPas.

Example 15

A method for preparing modified engineering polyester by using byproducts generated after chemical recycling of regenerated fiber vitamins comprises the following steps:

(a) mixing ethylene glycol byproduct, catalyst, metal chelating agent, cross-linking agent and benzoic acid byproduct according to the mass ratio of 700: 11.1: 48: 73: 2100, stirring and heating to 160 ℃ for esterification reaction for 4 hours, and successively cutting 120 ℃ front fraction and 120 ℃ above fraction;

the ethylene glycol byproduct comprises, by mass, 29.3% of EG, 9.3% of DEG, 16.5% of BHET monomer, 41.6% of BHET with the polymerization degree of 2-6, 3% of potassium carbonate and the balance of water; the catalyst is 98.3 wt% concentrated sulfuric acid; the metal chelating agent is one or more of potassium salt chelating agents; the benzoic acid by-product comprises 22% of phthalic acid, 77% of methyl benzoic acid and 1% of benzoic acid in percentage by mass;

(b) continuously stirring and heating to 230 ℃, vacuumizing, carrying out polymerization reaction for 5 hours at 245 ℃, and cutting ethylene glycol fraction through a rectifying tower; when the temperature of the top of the rectifying tower is reduced to 120 ℃, breaking vacuum and stopping heating, adding a mixed modifier of 1, 4-butanediol, trimethylolpropane and polyethylene glycol (the mass ratio of the ethylene glycol byproduct to the mixed modifier is 700: 170, and the molar ratio of the 1, 4-butanediol, trimethylolpropane and polyethylene glycol is 0.5: 1:1.2), preserving the temperature at 190 ℃ until the polymerization reaction is finished, discharging, cooling and crystallizing to obtain the polyester product for the waterproof agent. The waterproof performance of the waterproof agent prepared by the polyester product reaches 4 grades.

The stirring of the existing polyester reaction kettle is not uniform enough, the polymerization efficiency of polyester materials is reduced, the reaction effect is promoted to be limited, and in addition, due to the fact that the generated polyester materials are viscous, viscous products are adhered to the inner wall of the reaction kettle in the discharging process, discharging is difficult, and therefore improvement is needed.

As shown in fig. 1 to 5, the polyester reaction kettle used in each embodiment of the present invention comprises a kettle body 1 and a stirring device arranged in the kettle body 1, the stirring device comprises a guide shaft 2, a first stirring paddle 3 which passes through the guide shaft 2 in a rotating way, a driving cam 4 fixed on the guide shaft 2, a plurality of scraping pieces 5 which are circumferentially distributed on the outer ring of the first stirring paddle 3, a push rod 6 which is vertically and slidably connected with the guide shaft 2, and second stirring paddles 8 distributed on two sides of the first stirring paddle 3, the push rod 6 and the driving cam 4 are arranged from top to bottom, the scraping piece 5 is fixed on the driving cam 4, the side wall of the outer end of the scraping piece 5 is rotationally attached to the kettle body 1, the push rod 6 is driven by the driving cam 4 to move back and forth, the push rod 6 is vertically connected with a connecting rod 7, and two ends of the connecting rod 7 correspondingly drive the second stirring paddles 8 to move forward and backward through a rack-and-pinion structure 9. The guide shaft 2 is fixed at the top of the kettle body 1, the guide shaft 2 and the kettle body 1 are sealed through a sealing ring, and the first stirring paddle 3 is driven to rotate through the motor 13.

The driving cam 4 comprises a ring sleeve part 41 fixed on the shaft of the first stirring paddle 3 and a ring part 42 arranged on the outer ring of the ring sleeve part 41, the ring part 42 is formed by mutually connecting semi-elliptical arc rings 421 uniformly distributed on a plurality of circumferences, and the ring part 42 is connected with the ring sleeve part 41 through a plurality of connecting parts 43.

The scraping piece 5 comprises a connecting shaft 51 connected to the outer end part of the semi-elliptic arc ring 421 and a scraping plate 52 connected to one side of the connecting shaft 51, and the scraping plate 52 is attached to the inner wall of the kettle body 1. The scrapers 5 rotate along with the rotation of the driving cam 4, and the scrapers 5 form stirring blades taking the first stirring paddle 3 as a shaft, have a stirring effect and can simultaneously scrape off products adhered to the inner wall of the kettle body 1.

The push rod 6 comprises a through groove part 61 and rod parts 62 connected to two ends of the through groove part 61, the guide shaft 2 penetrates through the through groove part 61 and is in sliding connection with the through groove part 61, guide posts 63 are formed on the lower surface of the rod parts 62 in a protruding mode, the two guide posts 63 are horizontally distributed on two sides of the ring part 42, and the guide posts 63 are in butt joint with the outer wall of the ring part 42. In the present invention, the number of the semi-elliptical arc rings 421 is three, the ring portion 42 is three-lobed, and in the initial state, one of the guide posts 63 abuts against the top end of one of the semi-elliptical arc rings 421, and the other guide post 63 abuts against the joint of the other semi-elliptical arc rings 421. Referring to fig. 3, three semi-elliptical arc rings 421 are set to be a semi-elliptical arc ring a 421, a semi-elliptical arc ring B421 and a semi-elliptical arc ring C421 in a counterclockwise direction, the left guide post 63 abuts on the joint of the semi-elliptical arc ring B421 and the semi-elliptical arc ring C421, the right guide post 63 abuts on the top end of the semi-elliptical arc ring a 421, when the driving cam 4 rotates, the ring portion 42 pushes the left guide post 63 to move the push rod 6 to the left, and when the left guide post 63 abuts on the top end of the semi-elliptical arc ring B421, the right guide post 63 abuts on the joint of the semi-elliptical arc ring C421 and the semi-elliptical arc ring a 421.

The rack and pinion structure 9 comprises a rack 91 and a gear 92 engaged with the rack 91, the rack 91 is vertically connected with the connecting rod 7, and the second stirring paddle 8 is fixed on the gear 92.

The cauldron body 1 is including fixing annular baffle 11 in cam 4 below, the epaxial carousel 12 that is fixed with of first stirring rake 3, carousel 12 rotates with baffle 11 to be connected, scraper 5 is fixed to be passed carousel 12, and second stirring rake 8 rotates to pass baffle 11. Specifically, an annular slide rail 111 is arranged on the partition plate 11, and a slide groove 121 matched with the slide rail 111 is formed in a concave manner on the lower surface of the turntable 12. When first stirring rake 3 rotated, drive cam 4 and rotate, drive carousel 12 through first stirring rake 3, scraper 5 and rotate, carousel 12 and baffle 11 formation baffler prevent that the subassembly from receiving product pollution more than the baffle 11. The turntable 12 and the partition 11 may also be sealed by a seal.

The top of the kettle body 1 is respectively fixed with a pair of first supports 14 and two pairs of second supports 15, the push rod 6 is slidably arranged on the pair of first supports 14, and the rack 91 is correspondingly slidably arranged on the pair of second supports 15.

This polyester reation kettle during operation, at first stir through first stirring rake 3, 3 rotatory drive cams 4 of first stirring rake rotate, and then make 5 rotations of scraping, in the time of drive cams 4 pivoted, promote 6 back and forth movements of push rod, and then make second stirring rake 8 stir with positive reverse rotation in turn, setting through the multiple stirring of the aforesaid, the homogeneity and the stirring efficiency of stirring have been improved, the high-efficient mass transfer of reaction has been promoted, heat transfer, be favorable to going on of reaction, and can prevent the adhesion of polyester material in reation kettle, it is smooth and easy to ensure the ejection of compact.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.