CN1058024C - Nylon 6 resin with excellent tension property and shock resistance and its preparation - Google Patents

Abstract

The invention discloses a nylon 6 resin with good stretchability and impact resistance and a preparation method thereof, which uses fine silicon dioxide particles and a general formula of NH ₂ Rm(ORn) ₃ Si aminosilane compound as a coupling compound. The coupling agent and the caprolactam monomer are firstly prepared as a mother liquor, and then mixed according to the weight ratio of the mother liquor and the caprolactam raw material as 1:20-30, and then polymerized, discharged, pelletized, extracted and dried to obtain a modified nylon 6 resin. The problem of low stretchability and impact resistance of nylon 6 resin is solved, and it has the advantages of simple manufacturing process, low cost, and ^high resin strength. The product is especially suitable for making biaxially stretched films and high toughness engineering plastics.

Description

Nylon 6 resin with good stretchability and impact resistance and preparation method thereof

The invention relates to a nylon 6 resin with good stretchability and impact resistance and a preparation method thereof.

In the prior art, nylon 6 is a polymer material with a wide range of uses, but the elongation at break of general nylon 6 resin is about 30%, and the notched impact strength is about 6KJ/m ² (see domestic PA6 product standard HG -868-76, the test method adopts GB-1040-79), for films with higher stretching ratios (such as biaxially oriented films) and engineering plastics with high toughness requirements, the tensile properties and impact resistance properties cannot be fulfil requirements. In order to improve the stretchability and impact resistance of nylon 6, it is necessary to physically or chemically modify nylon 6. The commonly used physical modification method is to add a certain amount of modifier and melt blend in a twin-screw extruder. . In "Engineering Plastics Application" (edited by Liu Chunxiao, 1996, Vol.24(1), P34), it is reported that maleic anhydride grafted polypropylene is used as a compatibilizer, and more than 10% polypropylene is added to melt and mix in a twin-screw , the elongation at break of the prepared nylon 6 alloy is 250%, and the notched impact strength is 28KJ/m ² . However, this method requires secondary granulation and the preparation of a special compatibilizer, the process is complex, the cost is high, and the product can only be used as engineering plastics, not as a film. In "Engineering Plastics Application" (Fang Hailin, 1996, Vol.24 (2), P15), it is reported that rare earth minerals are used as PA6 modifiers, and 15% rare earths are added to melt and knead in twin-screws. The notched impact strength of permanent PA6 is increased from 5.5KJ/m ² to 8.5KJ/m ² . This method also requires secondary granulation, and the notched impact strength of the product is slightly improved. The commonly used chemical modification method is to introduce a second nylon monomer (such as nylon 66 salt) for co-condensation during the polymerization process. The elongation at break and notched impact strength of the prepared copolymerized nylon resin can be greatly improved compared with pure PA6. The elongation at break of the copolymerized nylon CM6041 (Nylon 6/66 copolymer of Toray Corporation) reported in the "Polyamide Resin Handbook" (P385, edited by (Japan) Fukuda, translated by Shi Zupei, etc., China Petrochemical Press) It is greater than 200%, and the notched impact strength is greater than 30KJ/m ² , but this method has higher requirements on the polymerization process, and the general nylon 6 polymerization device cannot meet the requirements.

The purpose of the present invention is to provide a nylon 6 resin with good stretchability and impact resistance and a preparation method thereof prepared in the polymerization process by adding a small amount of additives on the existing nylon 6 polymerization device, without adding The auxiliary agent is granulated twice in the screw. The preparation process is simple, the cost is low, and the product has good stretchability and impact resistance. It is especially suitable for the preparation of nylon 6 biaxially stretched film and high-toughness engineering plastics.

The purpose of the present invention is achieved through the following technical solutions: first prepare the caprolactam mother liquor containing amorphous silicon dioxide and coupling agent, then add the mother liquor to the caprolactam monomer for polymerization, and the specific process mainly includes: (1) preparation Mother liquor, using fine silica particles, and using aminosilane compounds with general formula NH ₂ Rm(ORn) ₃ Si (in the formula, R is CH ₂ , n is a positive integer of 1 to 3, m is 2 to 3 One or more of another arbitrary positive integer of 18) is used as the coupling agent, and the coupling agent and Add amorphous silica to caprolactam molten monomer at 80-100°C, heat and stir for half an hour to obtain mother liquor; (2) polymerize, mix according to the weight ratio of mother liquor and caprolactam monomer raw materials in a ratio of 1:20-30 , react for 1 to 2 hours at a temperature of 250 to 270°C and a pressure of 0.1 to 0.5MPa, and react for 2 to 4 hours at 250 to 270°C under normal pressure or negative pressure after depressurization; Raw material, pelletized, the slices were extracted with hot water at 90-100°C for 6-12 hours, and then dried at a temperature of 100-120°C under vacuum conditions for 12 hours to prepare nylon 6 resin containing fine silica additives .

The preferred technical scheme of the present invention can be: the coupling agent of preparation mother liquor adopts silane compound, preferably uses general formula to be the aminosilane compound of NH ₂ Rm(ORn) ₃ Si, such as aminopropyl tri(ethyl) Oxy)silane, Aminooctyltri(methoxy)silane, Aminocapryltri(propoxy)silane, Aminopropyltri(propoxy)silane, Aminooctadecyltri(ethoxy)silane, etc. . In the process of preparing nylon 6, the coupling agent can be one, two or more of the aforementioned compounds used in combination, all of which can achieve the same effect. The silica used is preferably amorphous fine particles such as silica with a particle size ranging from 10 to 100mm. Silica is an additive that mainly plays a role in toughening, and the coupling agent can improve the performance of silica and silica. The role of compatibility between nylon, is a surface modifier of silica particles. In the process of preparing the mother liquor, the silica: coupling agent: caprolactam (weight ratio) is generally 1:0.05～0.3:10～50. If the amount of silica is too much, it will be difficult to disperse in the system. The coupling agent The dosage should be appropriate. Excessive dosage will not only increase the cost, but also reduce the physical and mechanical properties of nylon 6 products such as hardness and tensile strength.

The preferred technical scheme of the present invention can also be: in the process of preparing nylon 6 resin, the addition of fine silicon dioxide granules is 0.1%～0.3% (weight) of total amount (or resin amount) of system, can be like this The best toughening effect is achieved, and the dispersion of silicon dioxide is good, and the production cost is low. Obviously, if the amount of silicon dioxide is too low, the expected toughening effect will not be achieved on the product, which will affect the tensile properties and impact resistance of the product; there is no need to add too much silicon dioxide. It is difficult to disperse in the system, and the product performance is unstable.

The preferred technical scheme of the present invention can also be: in the process of preparing nylon 6 resin, the addition of coupling agent is 10%～20% (weight) of amorphous silicon dioxide amount, can compare within this dosage range Improve the compatibility between nylon 6 and silica, which is beneficial to improve the toughening effect of silica and improve the physical and mechanical properties of the resin.

Compared with the prior art, the present invention has the following obvious advantages:

1. Using the method of preparing mother liquor first, adding silica and coupling agent to the system for polymerization, the coupling agent can be concentrated on the surface of silica first, which can save the surface treatment process of silica and prevent The coagulation of silicon dioxide directly prepares the modified resin during the polymerization process, which saves the secondary granulation process of the screw commonly used in resin modification, so the manufacturing process is simple and the cost is low.

2. Amino silane compounds are used as coupling agents. There is a good affinity between amine and nylon, and silane and silicon dioxide have good affinity, so it can better improve the performance of nylon and silicon dioxide. Compatibility between them, fine silica particles can significantly improve the tensile properties and impact resistance of nylon 6, the elongation at break of nylon 6 resin can reach more than 250%, and the notched impact strength can reach more than 25KJ/ ^m2 , The two indicators are respectively 8 times and 4 times higher than the general nylon 6 resin, so the product quality is good, and the product is suitable for the preparation of biaxially stretched films and high-toughness engineering plastics, which broadens the application field of nylon 6 resin.

The present invention is described in further detail below by specific embodiment:

Example 1: Weigh 100 grams of caprolactam, heat it to 80-100° C. in a beaker, add 0.8 grams of aminopropyl tri(ethoxy)silane and 4 grams of fine amorphous silicon dioxide after melting, and keep stirring for 30 minutes Afterwards, the mother liquor is obtained, and this mother liquor and 1900 grams of caprolactam are added to a reaction kettle with a volume of 5 L, and the reaction is carried out at a temperature of 250 to 270 ° C and a pressure of 0.1 to 0.5 MPa for 1.5 hours. React at ~270°C and normal pressure for 3 hours, discharge, pelletize, extract the slices with hot water at 90-100°C for 6 hours, and then dry at 120°C under vacuum for 12 hours to obtain modified nylon 6 resin . The elongation at break and the notched impact strength of this nylon 6 resin were measured by the national standard method (GB-1040-79 and GB-1043-79), and the values were 268% and 30.2KJ/m ² respectively.

In this embodiment, the weight of _SiO2 is 0.2% of the weight of the resin, the weight of the coupling agent is 0.04% of the weight of the resin, and the amount of the coupling agent added is 20% of the weight of silicon dioxide.

Embodiments 2 to 6: The steps and methods are the same as in Example 1, and the process control is the same as in Example 1. The amount of silicon dioxide and coupling agent added, and the corresponding physical and mechanical properties (test standards are the same as before) are shown in Table 1.

Table 1 Raw material composition and physical and mechanical properties of nylon 6 resin Example Mother liquor composition Amount of monomer for polymerization (g) content in the system physical and mechanical properties _Amount of SiO2 (g) coupling agent Coupled dose (grams) Monomer weight (g) SiO ₂ (%) Coupling agent (%) Elongation at break (%) Notched impact strength (KJ/m ² ) 1 4.0 ① 0.8 100 1900 0.2 0.04 268 30.2 2 6.0 ② 0.3 100 1900 0.3 0.015 256 28.0 3 10.0 ④ 0.92 100 1900 0.5 0.05 252 26.0 4 1.0 ①, ③ 0.2, 0.1 100 1900 0.05 0.015 302 29.8 5 2.0 ②, ④ 0.1, 0.3 100 1900 0.1 0.02 282 28.6 6 4.0 ①, ③, ⑤ 0.3, 0.2, 0.3 100 1900 0.2 0.04 296 32.3 Note: In the table ① is aminopropyl tri(ethoxy) silane, ② is amino octyl tri(methoxy) silane, ③ is amino octyl tri(propoxy) silane,

④ is aminopropyl tri(propoxy) silane, and ⑤ is amine octadecyl tri(ethoxy) silane.

Claims (3)

1. A preparation method of nylon 6 resin with good stretchability and impact resistance, comprising monomer preparation, polymerization, granulation, extraction and drying process, characterized in that: first prepare a The caprolactam mother liquor of the joint agent, and then add the mother liquor to the caprolactam monomer for polymerization. The specific process mainly includes: (1) Prepare the mother liquor, use fine silica granules, and use aminosilane compounds with the general formula NH ₂ Rm(ORn) ₃ Si (in the formula, R is CH ₂ , n is a positive integer of 1 to 3, m is another arbitrary positive integer of 2 to 18) as coupling agent, according to the weight ratio of silicon dioxide: coupling agent: caprolactam = 1: 0.05 ~ 0.3: 10 ~ 50, the coupling Add the agent and amorphous silicon dioxide to the caprolactam molten monomer at 80-100°C, heat and stir for half an hour to obtain the mother liquor, and then (2) Polymerization, the weight ratio of the mother liquor and the caprolactam monomer raw material is mixed in a ratio of 1:20 to 30, and reacted at a temperature of 250 to 270°C and a pressure of 0.1 to 0.5MPa for 1 to 2 hours, and after decompression, the React at 250-270°C for 2-4 hours under normal pressure or negative pressure, then (3) Discharging, pelletizing, extracting and drying. 2. The preparation method of nylon 6 resin according to claim 1, characterized in that the amount of fine silica particles added is 0.1% to 0.3% of the total weight of the system or the weight of the resin. 3. The preparation method of nylon 6 resin according to claim 1, characterized in that the amount of coupling agent added is 10% to 20% of the weight of silica.