Black-spot-free polyamide composition and polymerization process thereof

文档序号：1841431 发布日期：2021-11-16 浏览：24次中文

阅读说明：本技术 一种无黑点聚酰胺组合物及其聚合工艺 (Black-spot-free polyamide composition and polymerization process thereof ) 是由陈�胜崔权于 2020-09-17 设计创作，主要内容包括：一种无黑点聚酰胺组合物及其聚合工艺,本发明从原料、聚合工艺、条件控制多角度下手解决了该聚酰胺及其组合物的黑点技术难题。所述组合物其组分包括：二元酸和二元胺单体,总重占原料总重的90％以上；添加剂,总重占原料总重的10％以下。以上述配方准备原料,继续实施如下步骤：(1)成盐：反应釜在氮气保护下将原料溶入水中,配制成尼龙盐水溶液,控制尼龙盐浓度为40～90％；(2)升压预聚：逐步聚合,保压压力控制在0.2～2MPa(表压)；(3)负压终聚：待体系温度升至240～275℃时,抽真空使反应体系内压力降至-0.01～-0.1MPa(表压),并维持1～60min；(4)在惰性气体保护下进行加压造粒：体系加压至0.3-0.5Mpa,出料造粒,待出料结束后,在惰性气体保护下通道内无氧气接触。(The invention relates to a polyamide composition without black spots and a polymerization process thereof, which solves the technical problem of black spots of the polyamide and the polyamide composition from the aspects of raw materials, polymerization process and condition control. The composition comprises the following components: the total weight of the dibasic acid and the diamine monomer accounts for more than 90 percent of the total weight of the raw materials; the total weight of the additive accounts for less than 10 percent of the total weight of the raw materials. Preparing raw materials according to the formula, and continuously performing the following steps: (1) salifying: dissolving raw materials into water in a reaction kettle under the protection of nitrogen to prepare a nylon salt water solution, and controlling the concentration of nylon salt to be 40-90%; (2) pressure boosting and prepolymerization: gradually polymerizing, and controlling the pressure maintaining pressure to be 0.2-2 MPa (gauge pressure); (3) negative pressure final polymerization: when the temperature of the system rises to 240-275 ℃, vacuumizing to reduce the pressure in the reaction system to-0.01-0.1 MPa (gauge pressure), and maintaining for 1-60 min; (4) carrying out pressure granulation under the protection of inert gas: pressurizing the system to 0.3-0.5Mpa, discharging and granulating, and after the discharge is finished, making the channel be in contact with oxygen-free atmosphere under the protection of inert gas.)

1. A black spot-free polyamide composition, characterized in that the composition comprises the following components:

dibasic acid and diamine monomer as main components, the total weight of which accounts for more than 90 percent of the total weight of the raw materials;

the additive is a modified component, and the total weight of the additive accounts for less than 10% of the total weight of the raw materials.

2. The composition of claim 1, wherein the polyamide is obtained by polycondensation of two or more monomers selected from the group consisting of a dicarboxylic acid having five to eighteen carbon atoms and a diamine having five to eighteen carbon atoms.

3. The composition of claim 1, wherein the diacid and diamine monomers: comprises one or more of glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid and octadecanedioic acid, and;

the diamine monomer comprises one or more of pentanediamine, hexanediamine, heptanediamine, octanediamine, nonanediamine, decanediamine, undecamethylene diamine, dodecadiamine, tridecanediamine, tetradecanediamine, pentadecadiamine, hexadecanediamine, heptadecanediamine and octadecanediamine.

4. Process for the preparation of a polyamide composition according to any one of claims 1 to 3, characterized in that the starting materials are prepared according to the above formulation and the following steps are carried out:

(1) salifying: the reaction kettle carries out the reaction on the raw materials under the protection of nitrogenDissolve inPreparing a nylon salt aqueous solution in pure water, and controlling the concentration of nylon salt to be 40-90%;

(2) pressure boosting and prepolymerization: gradually polymerizing, and controlling the pressure maintaining pressure to be 0.2-2 MPa (gauge pressure);

(3) negative pressure final polymerization: when the temperature of the system rises to 240-275 ℃, vacuumizing to reduce the pressure in the reaction system to-0.01-0.1 MPa (gauge pressure), and maintaining for 1-60 min;

(4) carrying out pressure granulation under the protection of inert gas: pressurizing the system to 0.3-0.5Mpa, discharging and granulating, and after the discharge is finished, making the channel be in contact with oxygen-free atmosphere under the protection of inert gas.

5. The method according to claim 4, wherein the concentration of the nylon salt in the step (1) is 50 to 85%.

6. The method according to claim 5, wherein the concentration of the nylon salt in the step (1) is 60 to 80%.

7. The process according to claim 4, wherein the holding pressure in the step (2) is controlled to 0.4 to 1.8MPa (gauge pressure).

8. The production process according to claim 7, wherein the holding pressure in the step (2) is controlled to 0.5 to 1MPa (gauge pressure).

Technical Field

The invention belongs to the technical field of high polymer materials, and particularly relates to a black-spot-free polyamide composition and a polymerization process thereof.

Background

Polyamide, commonly known as nylon, refers to a linear thermoplastic polymer having repeat structural units of amide groups (-CONH-) in the main chain. The amide group in the polyamide has polarity to form intermolecular hydrogen bond, so the polyamide has the excellent characteristics of toughness, wear resistance, impact resistance, fatigue resistance, corrosion resistance, no toxicity, good spinnability, high fiber strength and the like, and is mainly used for the aspects of automobiles, electronics, spinning and the like. However, nitrogen atoms (amide groups and terminal amino groups) are introduced into polyamide, so that the thermal oxygen stability of the polyamide is poor, side reactions such as gel and carbonization are easily generated in the polymerization process to generate black spots, particularly, the phenomenon is more serious after multiple times of polymerization, the black spots in particles or melt on one hand cause defects on the appearance of products and also become weak links on injection molding parts to cause product quality reduction, more importantly, the black spots are easy to cause fiber breakage in the spinning process, the pressure of broken filaments or components is increased to influence the yield, the cost is greatly increased, the black spot problem is always a difficult problem which is difficult to solve in the polyamide industry, some manufacturers use black spot screeners to screen out particles with large black spots, but the black spot screeners cannot have small black spots, the capacity of the black spot screeners is generally low, and the production process and the cost are increased.

At present, the technical scheme of how to deal with the black spots is not disclosed in the field.

Disclosure of Invention

In order to solve the problem of black spots of polyamide and the composition thereof, the inventors of the present application provide a black spot-free polyamide and the composition thereof, and a polymerization process thereof.

The inventor finally finds the reason for the black spot according to a large number of experiments, and the reason is as follows:

the control factor (1) is that the salt concentration of polyamide and the raw materials thereof in the salt forming process is an important factor for controlling black spots, wherein the salt solution has too low concentration and the dissolved oxygen content in the solution is too high, so that the oxidation probability is increased at high temperature in the later period, and the black spots are increased; the salt solution has too high concentration and poor stability, and is easy to generate gel, thereby causing black spots;

controlling the factor (2) polyamide and the composition thereof, wherein the pressure maintaining pressure in the process can influence the fluidity of the solution, the poor fluidity of the solution is caused by too low pressure maintaining pressure, and black spots are generated by too high local heating; the pressure maintaining pressure is too high, the moisture content is slow, and the heating time of the system is too long, so that black spots are caused;

the system temperature of the control factor (3) is also an important factor for causing black spots, and when the system temperature is too high, the probability of generating the black spots is greatly increased due to easy gelation or carbonization of the polyamide composition at high temperature;

the discharging and granulating process of the control factor (4) is also a key factor causing the generation of black spots, and the air in the lower channel is easy to oxidize the polyamide composition at high temperature, so that the black spots are caused;

therefore, the invention solves the technical problem of black spots of the polyamide and the composition thereof from the aspects of raw materials, polymerization process and condition control.

The invention aims to provide a formula of a polyamide composition without black spots, and then discloses a polymerization process for preparing the polyamide composition without black spots.

The definition of the black-dot-free polyamide composition is that the component is polyamide, the polyamide is distributed in the polyamide composition at 0-10 grains/kg, and the diameter of the black-dot-free polyamide composition is more than 0.1 mm.

Technical scheme one

A polyamide composition, characterized in that the composition comprises the following components:

dibasic acid and diamine monomer as main components, the total weight of which accounts for more than 90 percent of the total weight of the raw materials;

the additive is a modified component, and the total weight of the additive accounts for less than 10% of the total weight of the raw materials.

Further defined, the polyamide is obtained by polycondensation of two or more monomers of dibasic acid containing five to eighteen carbon atoms and diamine containing five to eighteen carbon atoms.

By way of example and not limitation, the diacid and diamine monomers: comprises one or more of glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid, tetradecanedioic acid, pentadecanedioic acid, hexadecanedioic acid, heptadecanedioic acid and octadecanedioic acid, and;

Among them, the pentanediamine, hexanediamine, heptanediamine, nonanediamine, decanediamine, glutaric acid, adipic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, and hexadecanedioic acid can be prepared by a biological method, by way of example and not limitation. The biological method can be a method that the raw material is derived from bio-based substances or the preparation process utilizes biological fermentation.

The additiveThe polyamide is modified according to the application and the corresponding content is selected and designed for the optional components in the formula.The additiveOne or more selected from catalysts, end capping agents, defoaming agents, weather resisting agents, nucleating agents, antistatic agents, flame retardants, anti-ultraviolet agents and delustring agents. Arrangement in the technical solutionAdditive, not the creation of the technical scheme of the invention New, only conventional techniques.

The catalyst comprises one or more of phosphoric acid, phosphorous acid, organic matters or salts of hypophosphorous acid series.

The capping agent comprises a monofunctional amine or a monofunctional acid such as hexylamine, acetic acid, caproic acid, benzoic acid, and the like, and may also be one or more of a diamine or a diacid such as pentamethylenediamine, hexamethylenediamine, adipic acid, terephthalic acid, and the like.

The defoaming agent is polydimethylsiloxane.

The weather resisting agent comprises one or more of resorcinol, salicylate, benzotriazole, benzophenone, hindered amine and the like.

The crystallization nucleating agent comprises one or more of inorganic particles such as talc, silicon dioxide, kaolin, clay, boron nitride and the like, or metal oxides, high-melting point nylon and the like.

The antistatic agent includes one or more of alkyl sulfate type anionic antistatic agents (e.g., sodium alkylsulfonate), quaternary ammonium salt type cationic antistatic agents (e.g., octadecyl dimethyl quaternary ammonium nitrate), nonionic antistatic agents (e.g., polyoxyethylene sorbitan monostearate), betaine type amphoteric antistatic agents, and the like.

The flame retardant includes one or more of melamine cyanurate, hydroxides (e.g., magnesium hydroxide, aluminum hydroxide, etc.), ammonium polyphosphate, brominated polystyrene, brominated polyphenylene ether, brominated polycarbonate, brominated epoxy resin, or a combination of these brominated flame retardants with antimony trioxide, and the like.

The anti-ultraviolet agent comprises one or more of metal oxide (such as zinc oxide), nickel organic complex (such as 2, 2' -thiobis (4-tert-octylphenoloxy) nickel-n-butylamine complex), substituted acrylonitrile (such as 2-chloroacrylonitrile) and triazine compound (such as 2-hydroxyphenyl triazine);

the delustering agent is inorganic substances such as titanium dioxide and the like.

Technical scheme two

The preparation method of the polyamide composition prepares raw materials according to the formula of the composition, and continuously performs the following steps:

(1) salifying: the raw materials (diamine, diacid and/or diacid) are reacted in a reaction kettle under the protection of nitrogenAdditive) dissolved in purePreparing a nylon salt aqueous solution in water, and controlling the concentration of the nylon salt to be 40-90%, preferably 50-85%, more preferably 60-80%; the inventors have surprisingly found that a suitable concentration of nylon salt also contributes to the control of black spots, probably due to a reduced fluctuation of the solution position, reducing the chance of gel formation, but too high a concentration is detrimental to oxygen control and solution stability.

(2) Pressure boosting and prepolymerization: gradually polymerizing, and controlling the pressure maintaining pressure to be 0.2-2 MPa (gauge pressure), preferably 0.4-1.8 MPa, more preferably 0.5-1 MPa, wherein the proper pressure maintaining pressure has influence on melt flow type and moisture volatilization disturbance, and the parameters also have influence on the control of black spots.

(3) Negative pressure final polymerization: when the temperature of the system is increased to 240-275 ℃, the proper temperature of the system is undoubtedly the necessary condition for controlling the side reaction. Vacuumizing to reduce the pressure in the reaction system to-0.01 to-0.1 MPa (gauge pressure) and maintaining for 1-60 min.

(4) Carrying out pressure granulation under the protection of inert gas: pressurizing the system to 0.3-0.5Mpa, discharging and granulating, and after the discharge is finished, making the channel be in contact with oxygen-free atmosphere under the protection of inert gas.

Pure water is used as a reaction solvent in the step (1), and the water is completely evaporated in the subsequent steps (2) and (3), and the actual water is not involved in the final product polyamide composition.

The inert gas is preferably nitrogen, argon and carbon dioxide.

The application comprises the following steps:

the polyamide composition of the present invention can be molded into a desired shape by a method such as injection molding, film molding, melt spinning, blow molding, or vacuum molding, and can be used for injection molded articles, films, sheets, monofilaments, tapes, fibers, and the like, or can be used for adhesives, coatings, and the like.

The technical scheme of the invention has the following beneficial effects:

the polyamide composition finally obtained by the comprehensive technical schemes of formula design, process, condition control and the like can reach the polyamide composition without black spots, and the polyamide composition without black spots is characterized in that: the content of black spots with a diameter of more than 0.1mm is controlled in the range of 0 to 10 particles per 1000 g of the polyamide composition.

The polyamide composition disclosed by the invention has extremely low content of black spots and even does not contain black spots, so that the quality and the processing cost of downstream engineering plastics, film products and fiber products are greatly improved. The preparation process can effectively inhibit the generation of black spots without adding additional production devices and processes. Solves the problem of black spots in the production of polyamide for a long time, and has very important production and application prospects.

Drawings

FIG. 1 is a summary of all example and comparative example records

Detailed Description

The production equipment related to the invention is the prior art, and the innovation point of the invention is not equipment.

The present invention will be further described with reference to the following specific examples. It should be understood that the following examples are illustrative only and are not intended to limit the scope of the present invention. In various embodiments, the summary enters the table organized in FIG. 1. The details are as follows.

The invention uses the following characterization method for performance characterization:

1. viscosity number

Concentrated sulfuric acid method with Ubbelohde viscometer: accurately weighing 0.25 + -0.0002 g of dried nylon sample, adding 50mL of concentrated sulfuric acid (96%) to dissolve, measuring and recording the flowing time t of the concentrated sulfuric acid in a constant-temperature water bath at 25 DEG C₀And nylon solution flow time t.

Viscosity number calculation formula: viscosity number VN ═ t/t₀-1)/C

t- -time of solution flow

t0- -time of solvent flow through

C- -concentration of Polymer (g/mL)

2. Melting Point Tm

The melting point of the sample was measured using a Perkin Elmer DSC8500 analyzer under nitrogen atmosphere at a flow rate of 40 mL/min. During testing, the temperature is firstly increased to 280 ℃ at the speed of 10 ℃/min, the temperature is kept at 280 ℃ for 1min, then the temperature is cooled to room temperature at the speed of 10 ℃/min, the temperature is increased to 280 ℃ at the speed of 10 ℃/min, and the endothermic peak temperature at the moment is taken as the melting point Tm.

3. Content of black dots

The black spot content is the number of black spots which are visible in every 1000 g of the polyamide composition and are isolated and dispersed on the surface of the polyamide composition, and the size of the black spots is impurities with the diameter of more than 0.1mm, and the size of the black spots does not exceed the particle size of the polyamide composition. The definition in the invention is that the number of the black dot-containing particles in 1000 g of nylon particles exceeds 100, and the nylon particles are unqualified products.

Example 1 preparation of Polyamide 66 (50% strength)

A20-liter polymerization kettle was evacuated and purged with nitrogen three times, protected with nitrogen, 5.8kg of pure water was added thereto, 2.57kg of hexamethylenediamine was added thereto, stirring was started, 3.23kg of adipic acid was added thereto, and 0.58g of antioxidant H10 (Bluegman, Germany) was added to prepare a nylon salt aqueous solution, which was adjusted to pH 7.92 at 10% concentration with a small amount of hexamethylenediamine or adipic acid.

And (3) raising the temperature of the 20L polymerization kettle oil bath to 270 ℃, starting to exhaust when the pressure in the kettle rises to 1Mpa, continuing to heat, vacuumizing to-0.04 Mpa (gauge pressure) when the temperature in the kettle reaches 272 ℃, and keeping the vacuum degree for 25min to obtain the polyamide 56.

And (3) filling nitrogen into the polymerization kettle to a pressure of 0.5Mpa, starting melting and discharging, granulating by using a granulator, feeding nitrogen into a melt flow channel behind a discharging bottom valve after the granulation is finished, cooling under the protection of nitrogen for repeated polymerization, and detecting the oxygen content in the channel to be 120ppm after the cooling. The polyamide particles were dried at 80 ℃ for 8 hours under vacuum, and then the respective properties were measured, and the results are shown in Table 1.