Rapidly crystallized high-temperature nylon material

Abstract

The invention provides a rapidly crystallized high-temperature nylon material, a resin polymeric monomer comprises binary acid and diamine, the binary acid comprises terephthalic acid, the diamine comprises pentamethylene diamine and methyl pentamethylene diamine, the molar ratio of the pentamethylene diamine to the methyl pentamethylene diamine is 1: 4-2: 1, and the molar ratio of the pentamethylene diamine to the methyl pentamethylene diamine is 1: 1-2: 1. The resin is subjected to melt processing to prepare fibers with monofilament diameters of less than 200 microns. The heat aging property is excellent, the crystallization rate is higher, and the processing efficiency is high.

Description

Technical Field

[0001] The invention relates to the technical field of engineering plastics, and in particular to a fast-crystallizing high-temperature nylon material. Background Art

[0002] Nylon is the most widely used engineering plastic, widely used in electronics, electrical, machinery and other fields. The most commonly used nylons are aliphatic PA6 and PA66, with melting points of about 220℃ and 265℃ respectively. With the increasing requirements for high temperature resistance, aliphatic nylon can no longer fully meet the requirements, and semi-aromatic high-temperature nylon has become a material of concern. Usually, aromatic dibasic acids such as terephthalic acid are introduced to increase the rigidity of the molecule, thereby improving the performance of the material. However, the most commonly used diamine monomer hexamethylenediamine is directly copolymerized with terephthalic acid, and the product PA6T has a melting point of up to 370℃, which is close to the decomposition temperature of the material and cannot be melt processed.

[0003] In order to lower the melting point of pure PA6T, other monomers are usually introduced for copolymerization. For example, adipic acid is used to obtain PA6T / 66, and the melting point can be reduced to a suitable range for melt processing, but the glass transition temperature of the material is reduced and the crystallization becomes slower, which affects the stability of the spinning process. During spinning, the stability of homopolymer PA66 with good crystallization performance is also much better than that of copolymer PA66 containing a third monomer with worse crystallization performance. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a fast-crystallizing high-temperature nylon material, which can be melt-processed, has excellent heat aging performance, faster crystallization rate and high processing efficiency.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is:

[0006] A fast-crystallizing high-temperature nylon material, wherein the resin polymerization monomers include a dibasic acid and a diamine, wherein the dibasic acid includes terephthalic acid, and the diamines include pentamethylenediamine and methylpentamethylenediamine, wherein the molar ratio of pentamethylenediamine to methylpentamethylenediamine is 1:4 to 2:1, and the resin is melt-processed to produce fibers with a single-filament diameter of less than 200 microns.

[0007] Terephthalic acid has good symmetry, stable source and low cost, and is a common raw material for synthesizing semi-aromatic nylon. Pentamethylenediamine is a bio-based diamine with a wide source and low cost. Methylpentamethylenediamine is the main byproduct of the synthesis of hexamethylenediamine by the butadiene method, and its source is also stable. In addition, the main chains of the two diamines are both 5 carbon atoms. After copolymerization with terephthalic acid, the position of the hydrogen bonds will not be staggered, so the obtained polymer has a very fast crystallization rate, which is very suitable for high-efficiency injection molding, spinning and other processing. At the same time, since the main chains of the two amines of the present invention are only 5 carbon atoms, the glass transition temperature is higher and the long-term heat resistance is good.

[0008] When pentamethylenediamine is copolymerized with terephthalic acid alone, the melting point of the product PA5T is as high as over 350°C, which is also not suitable for melt processing. The presence of methyl side chain of methylpentamethylenediamine will affect the regularity of the product molecular chain, thereby affecting crystallization. Therefore, it is necessary to control the molar ratio of pentamethylenediamine and methylpentamethylenediamine in the diamine monomer to be 1:4 to 2:1.

[0009] The molar ratio of pentamethylenediamine to methylpentamethylenediamine of the present invention is 1:2.5 to 1.5:1, and the melt processing performance is better.

[0010] The polymerizable monomers of the present invention contain other diamines or dibasic acids in a molar ratio not exceeding 5%. The properties of the final product can be adjusted by introducing other monomer diamines and dibasic acids, but in order to avoid destroying the regularity of the molecular chain, the molar ratio of other monomers is not higher than 5%.

[0011] The high-temperature nylon material of the present invention has a melting point higher than 290°C and a glass transition temperature higher than 130°C.

[0012] Preferably, the melting point of the high temperature nylon material is lower than 350°C.

[0013] This temperature range ensures the high temperature resistance of nylon materials while meeting the requirements of melt processing. At the same time, the glass transition temperature is higher than 130°C, with excellent thermal aging performance, faster crystallization rate and high processing efficiency.

[0014] The beneficial effects of the present invention are:

[0015] 1. Since the number of carbon atoms in the main chains of pentamethylenediamine and methylpentamethylenediamine is the same, the polymer molecules have high regularity and the crystallization rate of nylon materials is fast, close to PA9T and PA10T.

[0016] 2. Since the molecular chains of pentamethylenediamine and methylpentamethylenediamine are shorter than those of long-chain diamines such as nonanediamine and decanediamine, the glass transition temperature of nylon materials is higher than that of PA9T and PA10T, and the temperature resistance is better.

[0017] 3. Since the molecular weight of pentamethylenediamine and methylpentamethylenediamine is smaller than that of long-chain diamines such as nonanediamine and decanediamine, when small molecular diamines are copolymerized with terephthalic acid, the amount of low-cost terephthalic acid is larger, making the cost of nylon materials lower. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the DSC chart of the nylon fiber product of Example 10. DETAILED DESCRIPTION

[0019] In order to more clearly and in detail illustrate the technical solution of the present invention, the present invention is further described below through relevant embodiments. The following embodiments are only for specific explanation of the implementation method of the present invention, and do not limit the protection scope of the present invention.

[0020] The melting point of the existing product PA6T is as high as 370°C, which is close to the material decomposition temperature and cannot be melt processed. In order to lower the melting point of pure PA6T, other monomers need to be introduced for copolymerization, such as adipic acid, isophthalic acid, pentamethylenediamine, etc., to destroy the molecular regularity and lower the melting point to below 330°C to meet the needs of melt processing. However, the introduction of these monomers will cause the position of molecular hydrogen bonds to be staggered, thereby reducing the crystallization rate and affecting the processing efficiency.

[0021] Example

[0022] A fast-crystallizing high-temperature nylon material, wherein the resin polymerization monomers include a dibasic acid and a diamine, wherein the dibasic acid includes terephthalic acid, and the diamines include pentamethylenediamine and methylpentamethylenediamine, wherein the molar ratio of pentamethylenediamine to methylpentamethylenediamine is 1:4 to 2:1, and the resin is melt-processed to produce fibers with a single-filament diameter of less than 200 microns.

[0023] Terephthalic acid and diamine are prepared into a nylon salt solution in an aqueous solution at a molar ratio of 1:1, and the nylon salt solution is added into a nitrogen-filled high-pressure prepolymerization kettle, and the temperature is raised to 230°C for prepolymerization for three hours, and then the pressure is slowly released, and polymerized for thirty minutes at 280-330°C and -0.06Mpa, and polymerized by extrusion granulation through a melt pump to obtain polymer particles. The polymer particles are obtained by solid phase polymerization to obtain nylon resin.

[0024] After the nylon resin is melted by a twin-screw extruder, it is extruded by a melt pump, spun by a spinneret, drawn and wound to prepare nylon fiber products with a single filament diameter of less than 200 microns.

[0025] The present invention uses different diamine monomers and terephthalic acid to polymerize the nylon resin obtained according to the above-mentioned preparation method, and conducts a spinning experiment. The melting point and glass transition temperature are measured by DSC, and the heating and cooling rates are both 20°C / min. The melting point refers to the highest peak temperature of the melting signal at a heating rate of 20°C / min, and the glass transition temperature refers to the midpoint temperature of the glass transition signal. The crystallization half-peak width refers to the time between a horizontal line at half the height of the crystallization peak and the two intersections of the crystallization peak, which is used to evaluate the crystallization rate of the material. The crystallization peak temperature refers to the peak temperature of the DSC cooling curve. The smaller the difference between it and the melting point, the faster the material crystallizes (the crystallization half-peak width is a parameter used to characterize the crystallization rate. The smaller the data, the faster the crystallization). The following table shows the performance of nylon fiber products made from different diamine monomers:

[0026]

[0027] The results show that long-chain diamines such as nonanediamine and decanediamine can be copolymerized with terephthalic acid to obtain nylon with a melting point of less than 320°C, but the glass transition temperature is reduced due to the elongation of the flexible part of the molecule, which affects the long-term thermal aging performance of the material. In addition, since the molecular weight of nonanediamine and decanediamine is larger than that of hexamethylenediamine, the proportion of diamines when copolymerized with terephthalic acid is larger. In fact, the cost of diamines is much higher than that of terephthalic acid, which makes the cost of the final product high and limits its application and promotion.

[0028] Since the main chain lengths of pentamethylenediamine and methylpentamethylenediamine are the same, the molecular chains after copolymerization are the most regular. When the two diamines are copolymerized, at the same copolymerization ratio, the melting point can be controlled below 350°C and above 300°C. It can be used for melt processing and has the fastest crystallization. The half-peak width is basically the same as that of the polymer using only one amine, and is much smaller than other combinations.

[0029] The present invention further adjusts the molar ratio of methylpentamethylenediamine / pentamethylenediamine, and polymerizes the obtained nylon resin with terephthalic acid, and performs spinning experiments in the same manner as above, and then compares the performance data of the commercially available nylon fibers:

[0030]

[0031]

[0032] As can be seen from the table above, when the molar ratio of pentamethylenediamine to methylpentamethylenediamine is 2:1, the melting point has reached 338°C, which makes processing difficult. Further increasing the ratio of pentamethylenediamine will result in a higher melting point and cannot be processed. When the molar ratio is 1:5, the half-peak width of crystallization is close to that of PA6T / 66, and the half-peak width of crystallization exceeds 10°C, indicating that the crystallization rate has been greatly reduced and does not meet the requirements. When the molar ratio of pentamethylenediamine to methylpentamethylenediamine is 1:4 to 2:1, it can meet the requirements of melt processing and rapid crystallization, and the best ratio is 1:2.5 to 1.5:1.

[0033] PA9T and PA10T are high-temperature nylons with very high crystallization rates, and their crystallization rates are much higher than those of the common PA6T / 66 with the largest usage. The crystallization rate described in the present invention has reached a level close to that of PA9T and PA10T. Since the price of terephthalic acid is much lower than that of diamines, and the diamines used in the present invention have a small molecular weight, the usage of terephthalic acid is larger, and the production cost is lower than that of PA9T and PA10T.

[0034] The above-mentioned embodiments only express the specific implementation of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A fast crystallizing high temperature resistant nylon material, characterized in that: The resin polymerization monomers include dibasic acid and diamine, wherein the dibasic acid includes terephthalic acid, and the diamine includes pentamethylenediamine and methylpentamethylenediamine, wherein the molar ratio of pentamethylenediamine to methylpentamethylenediamine is 1:4 to 2:1, and the resin is melt-processed to obtain fibers with a single filament diameter of less than 200 microns.

2. The fast crystallizing high temperature nylon material according to claim 1, characterized in that: The molar ratio of pentamethylenediamine to methylpentamethylenediamine is 1:2.5 to 1.5:

1.

3. The fast crystallizing high temperature nylon material according to claim 1, characterized in that: The polymerizable monomer contains other diamines or dibasic acids in a molar ratio not exceeding 5%.

4. The fast crystallizing high temperature nylon material according to claim 1, characterized in that: The melting point of the nylon material is higher than 290°C, and the glass transition temperature is higher than 130°C.

5. The fast crystallizing high temperature nylon material according to claim 4, characterized in that: The melting point of the nylon material is lower than 350°C.

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