阅读说明：本技术 一种绿色环保的聚酰胺树脂的制备方法 (Preparation method of environment-friendly polyamide resin ) 是由 李洋 于 2020-05-18 设计创作，主要内容包括：一种绿色环保的聚酰胺树脂的制备方法,按重量计,原料包括聚合单体二元酸5-60份、二元胺3-50份,以及反应性分散体系聚酰胺10-90份；将聚合单体反应分散到熔融状态的聚酰胺分散体系之中,发生聚合反应得到聚合物产物。整个工艺路线中不经历水或者乙醇中的成盐过程,并且产品不受成盐过程中温度、pH值等影响,质量非常稳定,解决了传统尼龙盐生产中耗水、耗能、耗时、质量不稳定的问题。(A preparation method of green and environment-friendly polyamide resin comprises the following steps of raw materials, by weight, 5-60 parts of polymerized monomer diacid, 3-50 parts of diamine and 10-90 parts of reactive dispersion system polyamide; and (3) dispersing the polymerization monomer into a molten polyamide dispersion system for polymerization reaction to obtain a polymer product. The whole process route does not undergo the salifying process in water or ethanol, the product is not influenced by the temperature, the pH value and the like in the salifying process, the quality is very stable, and the problems of water consumption, energy consumption, time consumption and unstable quality in the traditional nylon salt production are solved.)

1. The preparation method of the green and environment-friendly polyamide resin is characterized in that raw materials comprise, by weight, 5-60 parts of polymerized monomer diacid, 3-50 parts of diamine and 10-90 parts of reactive dispersion system polyamide, and polymerized monomers are reacted and dispersed into a molten polyamide dispersion system to be polymerized to obtain a polymer product.

2. The method for preparing environment-friendly polyamide resin as claimed in claim 1, wherein the reaction of acid and amine in the monomer to form salt, and the dehydration polymerization are carried out in the polyamide dispersion system in a molten state.

3. The method for preparing green and environment-friendly polyamide resin according to claim 2, wherein when the melting point of the monomer raw material is lower than that of the polyamide raw material, the dibasic acid, the diamine and the polyamide cannot be simultaneously fed into the reaction system.

4. The method for preparing green and environmentally friendly polyamide resin as claimed in claim 1, wherein the maximum temperature reached by the material in the step of dispersing the polymerized monomer is higher than the melting point of the crystalline polyamide or the glass transition temperature of the amorphous polyamide so that the polyamide can be melted.

5. The method for preparing green and environmentally friendly polyamide resin according to claim 1, wherein the maximum temperature reached by the material is 20 ℃ or more higher than the melting point of the crystalline polyamide.

6. The method for preparing environment-friendly polyamide resin as claimed in claim 5, wherein the polyamide product has a melting point higher than 230 ℃.

7. The method for preparing environment-friendly polyamide resin as claimed in claim 1, wherein the molar ratio of aromatic dibasic acid contained in the dibasic acid monomer is not less than 20%.

8. The method of claim 1, wherein the reactive dispersion polyamide is at least one selected from the group consisting of aliphatic polyamide, aromatic monomer-containing polyamide, ether bond-containing polyamide, and ester bond-containing polyamide.

9. The method for preparing environment-friendly polyamide resin according to claim 1, wherein the molar ratio of the monomer diacid to the diamine is 0.4-2: 1.

10. the method for preparing environment-friendly polyamide resin as claimed in claim 1, wherein the monomer diacid is added in a time not prior to the monomer diamine in the step of dispersing the polymerized monomers.

11. The method for preparing environment-friendly polyamide resin as claimed in claim 1, wherein the proportion of the dispersion polyamide in the raw material is not less than 10%.

Technical Field

The invention relates to the technical field of engineering plastics, in particular to a preparation method of environment-friendly polyamide resin.

Background

The most commonly used nylon polymerization processes today include both the nylon salt process and the melt polymerization process. In the process of preparing the nylon salt, water or ethanol and other strong polar organic solvents are consumed, and the stability of quality is ensured by controlling temperature, pH value and other key parameters. The added water is vaporized in the polycondensation process and then is volatilized, and the process consumes a large amount of energy.

Although water is not required to be added as a solvent in the melt polymerization process, diamine needs to be added in the melt state of the diacid in the melt polymerization process, the diacid is melted firstly in the process of the process and then the polymerization reaction is carried out, in order to avoid a large amount of concentrated heat release when the diacid and the diamine are combined in the feeding process and cause decomposition due to overhigh temperature, the diamine needs to be slowly added, the adding process can be as long as several hours, so the production efficiency of nylon production by the melt polymerization process is greatly limited, and the reaction efficiency is low. On the other hand, since the severe exotherm during the combination of diamine and diacid results in a substantial loss of the lower boiling diamine, it is generally true for the higher boiling monomer, which is usually a longer carbon chain and therefore the polyamide product, to avoid volatile loss of the monomer. For the monomer with smaller molecular weight, the traditional melt polymerization process is not suitable for the melt polymerization of the small molecular weight monomer amine because the volatility is strong, the density of amino or carboxyl is high, the monomer per unit mass is more exothermic in the mixing process, and the heat release in the mixing process of the amino and the carboxyl is difficult to control.

Disclosure of Invention

Aiming at the problems of the traditional nylon salt and melt polymerization process, the invention provides the preparation method of the environment-friendly polyamide resin, the whole process route does not undergo the salt formation process in water or ethanol, the product is not influenced by the temperature, the pH value and the like in the salt formation process, the quality is very stable, and the problems of water consumption, energy consumption, time consumption and unstable quality in the traditional nylon salt production are solved.

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

the preparation method of polyamide resin comprises the following steps of (by weight), preparing raw materials of 5-60 parts of polymerized monomer diacid, 3-50 parts of diamine and 10-90 parts of reactive dispersion system polyamide; and (3) dispersing the polymerization monomer into a molten polyamide dispersion system for polymerization reaction to obtain a polymer product.

The monomer diacid and the diamine are dispersed by using the polyamide as a medium, the diacid and the diamine meet in a polyamide dispersion system to generate a salt to generate a polymerization reaction, and the monomer diacid and the diamine can also react with the polyamide dispersion system and can also react with a low-molecular-weight condensation polymer generated in the polymerization process, so that the whole system is very uniform, and the condition that a certain component is incompatible cannot occur.

The processes of salt formation by reaction of acid and amine in the monomer and dehydration polymerization are carried out in a polyamide dispersion system in a molten state.

In general, the melting point of the aliphatic monomer is lower than that of the raw material of the polymer, and if all the materials are put into one step and then melted by heating, the acid and the amine are melted and mixed before the polyamide is melted, so that the heat release is not favorable for control. Therefore, it is preferable that the dibasic acid, the diamine and the polyamide are not simultaneously fed into the reaction system when the melting point of the monomer raw material is lower than that of the polyamide raw material.

When an aromatic acid is used as the monomer, since the melting point of the aromatic acid is higher than that of the polymer raw material, all the materials can be charged by using a strong shearing apparatus such as an internal mixer. This type of dispersing device, besides heating, also allows a rapid temperature rise of the system by strong shearing, so that the polyamide can be melted before a violent exotherm of acid and amine occurs. With the presence of the molten polymeric polyamide as the dispersing system, the exothermic heat of reaction of the aromatic acid and amine dissolved therein is more easily controlled. Therefore, the reasonable material adding sequence can be designed according to the characteristics of materials, equipment and the like.

In the dispersing step of the polymerized monomers, the maximum temperature reached by the material in the invention is higher than the melting point of the crystalline polyamide or the glass transition temperature of the amorphous polyamide, so that the polyamide can be melted. Because the polyamide has high polarity, the polar monomer of the dibasic acid and the diamine is very favorably dispersed after being melted, so that the preparation of the nylon salt by using water as a solvent is avoided. Although the polyamide has high viscosity, the monomer amine and the acid can react with the polyamide, so that the molecular weight of the polymer is reduced, the melting temperature of the whole system is reduced, the viscosity is also reduced, and the uniform mixing of the monomers is facilitated.

Conventional melt polymerization processes are generally applicable to higher boiling monomers, which are generally longer in carbon chain and therefore generally lower in melting point of the polyamide product, in order to avoid volatile loss of the monomer. For the monomer with smaller molecular weight, the volatility is strong, the density of the amino or carboxyl is high, the monomer per unit mass has more heat release, and the heat release in the mixing process of the amino and carboxyl is difficult to control, so the method is not suitable for the traditional melt polymerization. In the invention, because the melt dispersion system of polyamide is added, the proportion of amino and carboxyl in the system is diluted, the heat release is reduced, and the control is easy, so that the polyamide resin composition has advantages in melt polymerization of monomers with smaller molecular weight.

It is further preferred that the maximum temperature reached by the mass is above 20 ℃ above the melting point of the crystalline polyamide. The polyamide as the dispersion system needs to be sufficiently melted, and in order to improve the efficiency and solubility of the reaction, it is preferable that the maximum temperature of the material during the dispersion process be 20 ℃ or higher than the melting point of the polyamide. Otherwise longer dispersion times and stronger shear are required to complete the dispersion, affecting efficiency.

The method does not need to specially prepare the nylon salt in advance, so that the copolymerized nylon can be conveniently prepared by mixing and feeding a plurality of dibasic acids or diamine, and the performance of the product can be adjusted in a larger range. Even partial polybasic acid or polyamine can be added into the monomer, so that the product has a certain degree of crosslinking, and the temperature resistance of the product is improved.

The method is a universal method for preparing polyamide, and the used dibasic acid, diamine and polyamide raw materials can be selected at will according to performance requirements and cost factors.

The diamine is selected from: at least one of aliphatic diamine and aromatic diamine containing 2-20 carbon atoms.

Further preferably, the polyamide product has a melting point above 230 ℃. In the invention, because the polyamide melt dispersion system is added, the proportion of amino and carboxyl in the system is diluted, the heat release is reduced, and the control is easy, so that the polyamide melt dispersion system has more advantages in the melt polymerization of monomers with smaller molecular weight. The products of PA56, PA66 and PA46 prepared by diamine with no more than 6 carbons as monomer amine can effectively utilize the polymerization method of the invention, and the melting points of the polyamide products exceed 230 ℃.

The dibasic acid is selected from: at least one of aliphatic dibasic acid and aromatic dibasic acid containing 2-20 carbon atoms.

Preferably, the molar ratio of the aromatic dibasic acid contained in the dibasic acid monomer is not less than 20%.

The introduction of the aromatic monomer can greatly improve the temperature resistance of the polyamide. The aromatic dibasic acid has obvious cost advantage and wider application. However, the melting point of the aromatic dibasic acid is close to or exceeds the decomposition temperature, and the solubility in water and organic solvent is poorer than that of the aliphatic dibasic acid, so that the aromatic dibasic acid cannot be used in the traditional melting polymerization process of melting acid, and the control of preparing the nylon salt is more difficult than that of the aliphatic dibasic acid. The method of the invention has particular advantages in the polymerization of monomers containing aromatic dibasic acids to produce semi-aromatic nylon. Because the polyamide melt has strong polarity and the dispersion is carried out at high temperature, the aromatic dibasic acid can be sufficiently dissolved in the system after reacting with the polyamide, and even if part of the aromatic dibasic acid which can not be completely dissolved exists, the aromatic dibasic acid can be uniformly distributed in the system in a very fine particle mode. After the polymerization reaction occurs, all the aromatic dibasic acid will eventually be incorporated into the system as homogeneous phase as the proportion of polyamide in the system increases. Small amounts of aromatic dibasic acid are also soluble in the molten aliphatic dibasic acid, but when the aromatic dibasic proportion exceeds 20%, the dissolution of the conventional nylon salt method is very difficult, and compared with the method, the advantages of the invention can be more prominent.

The reactive dispersion polyamide of the present invention is at least one selected from the group consisting of aliphatic polyamide, aromatic monomer-containing polyamide, ether bond-containing polyamide and ester bond-containing polyamide.

The polyamide dispersion system of the present invention is very widely available, and besides conventional aliphatic polyamides and polyamides containing aromatic monomers, polyamides containing ether bonds and ester bonds can be used as a dispersion medium in the method of the present invention.

The molar ratio of the dibasic acid to the diamine is 0.4-2: 1. in order to obtain a final polymer of sufficiently large molecular weight, it is necessary to ensure a relative balance of the ratio of amino and carboxylic acid functional groups in the final polymerization system. The polyamide raw material can use amide oligomer with lower molecular weight as the polyamide raw material, and the content ratio range of amino and carboxyl in the oligomer raw material can be larger, so that the ratio of acid to amine raw material needs to be adjusted according to the ratio of amino and carboxyl in the oligomer raw material, the ratio of acid to amine in the final whole system is balanced, and a product with high molecular weight is obtained. Thus, in the present invention, the ratio of acid to amine in the three main starting materials can be adjusted between 0.4 and 2:1, thus allowing a wider source of starting materials according to the invention, and very primary amide oligomers, even oligoamides containing only a small number of repeating units, can be used as starting polyamides. The end group of the amide oligomer can be mainly amino, carboxyl or the ratio of amino to carboxyl, and even can be a primary polymer containing carboxylic acid or amine monomers which are not polymerized completely. The source may be an amide salt which has only undergone prepolymerization, or a low molecular weight polyamide which has been subjected to simple ring-opening polymerization, or even a head material in other polymerization processes or a polymerization waste product which has not been completely reacted, and may be used in the production process of the present invention. In this case, the ratio of the amine and the acid to be added to the starting material can be determined by measuring the amine value and the acid value of the oligomer. When the diamine or diacid is in excess in the whole system, amino-or carboxyl-terminated polyamides of various molecular weights can also be prepared using the process of the invention. The low molecular weight polyamide can be used as an important component in polyurethane and epoxy resin formulations.

The raw material dibasic acid and diamine can be the same as the monomer of the raw material polyamide so as to prepare homopolymerized polyamide, and can also be different so as to prepare copolymerized polyamide.

In the method of the invention, the adding sequence of the monomers is relatively flexible, and the monomers can be added at one time or in batches. Preferably, the monomer diacid is added at a time not prior to the monomer diamine in the dispersing step of polymerizing the monomers.

For the metal material of the common preparation reaction device, the corrosivity of acid is far higher than that of amine, so that the monomer acid is not added into the system before the monomer amine, a strong acid system can be avoided, more conventional material preparation equipment can be applied, and the investment in equipment is reduced.

Too small amount of polyamide as the dispersion greatly affects the efficiency of dispersion, and therefore, the proportion of polyamide in the raw material of the dispersion of the present invention is not less than 10%.

The process for the production of amides by the reaction of amines and acids produces water and the equilibrium constant of the reaction can be as high as 400 or more, so that the presence of water in the feed does not render the polymerization impossible, but the evaporation of water consumes a large amount of heat, resulting in an increase in energy consumption, so that the dry feed is more economical, preferably with a water content of not more than 5%.

The invention has the beneficial effects that:

1. the polyamide is used as a medium to disperse monomer dibasic acid and diamine, the dibasic acid and the diamine generate salt in a polyamide dispersion system instead of water, and the polymerization reaction is carried out, so that the whole polymerization reaction is carried out under the condition close to homogeneous phase, the salt forming process in water or ethanol is not carried out, the polymerization process is greatly simplified, and the generation of waste liquid in the preparation process of the nylon salt is avoided. The generated by-product theoretically only contains water generated in the polycondensation process, and the method is a green and environment-friendly high-temperature-resistant polymer synthesis method.

2. The invention adds the melting dispersion system of polyamide, dilutes the proportion of amino and carboxyl in the system, reduces the heat release amount, is easy to control, can better show advantages in the melting polymerization of monomers with smaller molecular weight, is particularly suitable for diamine monomers with small molecular weight, can improve the speed of adding amine into the system, and has high reaction efficiency, high polymer melting point and good temperature resistance.

3. The product produced by the process route of the invention is not influenced by factors such as temperature, pH value and the like in the preparation process of the nylon salt in the aqueous solution, and has good quality stability.

4. The polyamide raw material of the invention has wide sources, can be the finished product polyamide purchased in the market, and also can be the prepolymer oligomer of the polyamide, and comprises defective products generated in the manufacturing process, which can be used as the raw material, so that waste materials are not generated basically.

5. The molar ratio of the aromatic dibasic acid contained in the dibasic acid monomer is not less than 20 percent, and the solubility and the melting performance of the aromatic dibasic acid are far poorer than those of the aliphatic dibasic acid, so that the preparation of the nylon containing the aromatic dibasic acid is more difficult than that of the aliphatic nylon. The method of the invention fully utilizes the dispersion advantage of polyamide as a dispersion system, and is particularly suitable for preparing semi-aromatic high-temperature nylon containing aromatic dibasic acid.

Detailed Description

In order to more clearly and specifically illustrate the technical solution of the present invention, the present invention is further described by the following embodiments. The following examples are intended to illustrate the practice of the present invention and are not intended to limit the scope of the invention.