JPH0248019B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing polyamide molded articles with good mold releasability and high impact strength by alkaline polymerization of ω-lactam. Methods for polymerizing ω-lactams under the action of alkaline catalysts and cocatalysts, so-called alkaline polymerization methods, are known. The polyamide obtained by this method is
It has excellent mechanical strength such as tensile strength, bending strength, and initial elastic modulus, and is used as machine parts and industrial materials. However, when producing molded products directly using this method, conventionally, a mold release agent is applied to the surface of the mold or used as an internal mold release agent to facilitate the release of the molded product from the mold. Methods such as incorporating low molecular weight compounds have been used. In the method of applying a mold release agent to a mold, it is necessary to apply it each time the mold is molded, and it is difficult to apply the agent uniformly, making it difficult to obtain a molded product with a uniform surface. Particularly for molded products with complex shapes, coating itself is impossible. Furthermore, when a low molecular weight compound is used as an internal mold release agent, there are problems such as bleeding of the internal mold release agent from the molded article and a decrease in polymerization rate and physical properties. An object of the present invention is to obtain a polyamide molded product which is free from the above-mentioned drawbacks, that is, has good mold releasability and good physical properties, and particularly has high impact strength, by an alkaline polymerization method of lactams. . The object of the present invention is to synthesize ω-lactams into (1) alkaline catalysts, (2) polyfunctional cocatalysts and (3) repeating units. (Here, R ¹ represents a hydrogen atom or a methyl group,
R ² represents a hydrogen atom or an alkyl group. l, m
are each an integer greater than or equal to 1. ) and a polyoxyalkylene diamine,
Groups in copolymer (A)

This is achieved by polymerizing the formula and polyoxyalkylene diamine in the presence of the reacted reaction mixture (B) at a molar ratio of 1:20 to 5:1. According to the present invention, a polyamide with good mold releasability and high impact strength can be obtained without reducing the polymerization rate and polymerization rate. The copolymer (A) used in the present invention is generally ω-
Since it is not soluble in lactam, it is difficult to carry out uniform alkaline polymerization in the presence of this copolymer. However, the reaction mixture (B) of the copolymer (A) and polyoxyalkylene diamine surprisingly dissolves very well in the ω-lactam, so that the polymerization reaction can be carried out without any problem. The copolymer (A) is obtained by copolymerizing ethylene with a vinyl monomer having a carboxyl group or an ester group in its side chain. Specific examples of vinyl monomers having carboxyl or ester groups in their side chains include acrylic acid, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, Examples include isopropyl methacrylate and n-butyl methacrylate.
As the copolymerization method, a known radical polymerization method may be used. An ethylene group in the copolymer (A),
The molar ratio with the vinyl monomer having a polar group in the side chain is preferably 6<l/m<25. l/m
When is smaller than the lower limit, the polymerization rate and polymerization rate are significantly reduced during alkaline polymerization of ω-lactam. When l/m is larger than the upper limit, the reaction with polyoxyalkylene diamine becomes difficult and the solubility of the ω-lactam deteriorates. Further, the molecular weight of the copolymer (A) is preferably 500 to 50,000, particularly preferably 1,000 to 20,000. The polyoxyalkylene diamine has the formula H ₂ NR ³ CH ₂ (−OCH ₂ R ⁴ )− _o OCH ₂ R ⁵ NH ₂ (wherein R ³ , R ⁴ , and R ⁵ have the same or different carbon number 1)
to 3 alkylene groups, and n is an integer of 2 or more) is used. Specific examples include polyoxyethylenediamine,
Examples include polyoxypropylene diamine and polyoxytetramethylene diamine. The molecular weight of these compounds is not particularly limited, but is preferably 200 to 60,000. The reaction mixture (B) used in the present invention comprises the above copolymer (A) and polyoxyalkylene diamine,
It is obtained by reacting at a temperature of 180 to 270°C in the presence of an inert gas or under reduced pressure. In this case, the amount of polyoxyalkylene diamine used is preferably 0.2 to 20 mol per mol of carboxyl group or ester group of copolymer (A). If the amount of polyoxyalkylene diamine used exceeds the upper limit, the mold release effect will be reduced, and if it is less than the lower limit, the solubility of the reaction mixture (B) in ω-lactam will deteriorate. Further, the reaction time varies depending on the reaction temperature, but is usually 1 hour to 24 hours. This reaction is characterized by an amide group-forming reaction between the carboxyl group or ester group of the copolymer (A) and the amino group of the polyoxyalkylene diamine. The formation of this amide group is confirmed by infrared spectroscopy. That is, it is considered that polyoxyalkylene diamine was partially grafted onto the copolymer (A). Specific examples of the ω-lactam used in the present invention include γ-butyrolactam, δ-valerolactam, ε-caprolactam, ω-enantholactam, ω-capryllactam, ω-undecanolactam, and ω-laurinlactam. It will be done. These ω-lactams may be used alone or in combination of two or more. As the alkali catalyst, all compounds used in known alkaline polymerization methods of ω-lactams can be used. Specific examples include alkali metals, alkaline earth metals, their hydrides, oxides, hydroxides, carbonates, alkylated products,
Examples include alkoxides, Grignard compounds, sodium naphthalene, and reaction products of the above metals or metal compounds with ω-lactams, such as sodium salts and potassium salts of ω-lactams. The amount of the alkali catalyst used is preferably 0.05 to 10 mol%, particularly 0.2 to 5 mol%, based on the ω-lactam. As for the polyfunctional cocatalyst, all known polyfunctional compounds for alkaline polymerization can be used.
Specific examples thereof include polyisocyanates such as toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, hexathimelene diisocyanate, polymethylene polyphenyl polyisocyanate, diisocyanate modified with carbodiimide, hexamethylene-1,6-bis Carbamide lactams such as carbamide caprolactam, N,N'-diphenyl-P-phenylenebiscarbamide lactam, acid chlorides such as terephthaloyl chloride, adipic acid chloride, sebacic acid chloride, adipoyl biscaprolactam, terephthaloyl biscaprolactam, etc. Examples include polyacyllactams. Among these, diisocyanates and carbamide lactams are preferably used. The amount of reaction mixture (B) used is preferably 1 to 40% by weight based on the ω-lactam. If the amount used is less than the lower limit, it will not be possible to impart good mold release properties and impact strength to the resulting polyamide,
Even if the amount used is larger than the upper limit, no difference is observed in the effect, and the inherent physical properties of the polyamide are significantly deteriorated, which is not practical. The reaction mixture (B) can be added directly during the alkaline polymerization of the ω-lactam, but it is preferable to add it after reacting with a polyfunctional cocatalyst prior to the alkaline polymerization of the ω-lactam. When reacting prior to alkaline polymerization of ω-lactam,
The reaction mixture in the presence or absence of a reaction solvent
By bringing (B) into contact with a polyfunctional promoter,
Proceeds easily. As the reaction solvent, for example,
Examples include benzene, toluene, xylene, and molten ω-lactam. Industrially, it is preferable to use a molten ω-lactam as the reaction solvent, which does not need to be particularly separated from the reaction product. The reaction temperature is
The temperature is usually 10 to 200°C, preferably 80 to 150°C. Moreover, the reaction temperature in the case of using a molten ω-lactam as a reaction solvent is a temperature equal to or higher than its melting point. The amount of polyfunctional cocatalyst used is determined by the number of functional groups (a):
In particular, at a ratio greater than the number of amino groups in the reaction mixture (B) (including the number of carboxyl groups when using a copolymer (A) containing a vinyl monomer having a carboxyl group in the side chain as a copolymerization component). 1<a/
It is preferable to use it in a ratio such that b≦2. If the amount of the polyfunctional promoter used is less than this lower limit, the rate will be slow and the polymerization rate of the resulting polyamide will be low. Furthermore, even if the amount is greater than this upper limit, the effect remains the same. The alkaline polymerization of ω-lactam in the present invention can be carried out according to known methods. The polymerization temperature is higher than the melting point of the ω-lactam to be polymerized and lower than the melting point of the resulting polyamide. Polymerization time is usually 2 hours or less. In the present invention, the ω-lactam can also be polymerized in the presence of stabilizers such as plasticizers, fillers, fibers, blowing agents, dyes and pigments, and even antioxidants, which do not substantially inhibit the polymerization reaction. Preferred plasticizers include N-alkylpyrrolidone and dialkylimidazolidinone, and the amount used is ω-
Usually from 2 to 25% by weight, based on the lactam. Specific examples of fillers include calcium carbonate, wollastonite, kaolin, graphite, gypsum, feldspar, mica,
Examples include asbestos, carbon black, and molybdenum disulfide. Specific examples of fibers include milled glass, fibrous magnesium compounds, potassium titanate fibers, mineral fibers, graphite fibers, boron fibers, and steel fibers. The amount of fillers and/or fibers used is usually from 2 to 50% by weight, based on the omega-lactam. Specific examples of blowing agents include benzene, toluene, and xylene, and the amount used is usually 1 to 1% per ω-lactam.
It is 15% by weight. The present invention provides a method for producing round rods directly from ω-lactam by casting method or reaction injection molding method.
It is useful as a method for manufacturing molded products such as plates, pipes, and automobile parts. Furthermore, the polyamide obtained according to the present invention can be made into chips and used to form various molded products, sheets, fibers, etc. by injection molding, extrusion molding, etc. Next, examples will be shown. In the following, the polymerization rate is expressed as the time from the start of mixing of the monomer liquid until the monomer liquid becomes non-fluid. Furthermore, the mold release property was evaluated by performing polymerization in a test tube and measuring the time from the start of mixing of the monomer liquid until the polymerized product was peeled off from the glass wall. The monomer content in the molded product was measured according to JIS K6810. Izotsu impact strength (with notch) is ASTM D256-56
The measurement was carried out in an absolutely dry state according to the following. The infrared absorption spectrum was measured using an infrared spectrophotometer (manufactured by Shimadzu Corporation, IR-
430). Example 1 50 g of ethylene-ethyl acrylate copolymer (NUC6070, manufactured by Nippon Unicar, ethyl acrylate content: 8.5 mol%, MI250), polyoxypropylene diamine (Difurmine D-2000, manufactured by DiFerson Chemical, molecular weight approx. 2000)
Introduce 522.5g into the three-necked flask No. 1, and
The reaction was carried out at 240° C. for 13 hours while stirring under reduced pressure of Hg. In the infrared absorption spectrum of the resulting pale yellow reaction mixture, absorption due to the amide group at 1660 cm ^-1 was observed. 3g of reaction mixture to 26g of ε-caprolactam
The mixture was dissolved at 110° C., 0.83 g of hexamethylene diisocyanate was added, and the mixture was reacted for about 30 minutes. On the other hand, 0.27 g of sodium methylate was added to 30 g of dissolved ε-caprolactam and reacted at about 110°C.
The generated methanol was removed under reduced pressure to prepare an alkaline catalyst solution. Next, the two are mixed and stirred, and the mixture is immediately put into a test tube with an inner diameter of 30 mm immersed in an oil bath at 160°C, and while dry nitrogen is passed through it, the time for the mixture to become non-fluid and the time for it to be released from the glass wall. was measured. In this polymerization reaction, the concentration of hexamethylene diisocyanate relative to the total ε-caprolactam is 1/100 mol%, and the concentration of sodium caprolactam, which is an alkali catalyst, relative to the total ε-caprolactam is 1/100 mol%. Example 2 A polymerization test similar to Example 2 was conducted except that the concentration of sodium caprolactam relative to the total ε-caprolactam was 1/200 mol %. Comparative Example 1 0.87 g of hexamethylene diisocyanate was added with 29 g of substantially anhydrous ε-caprolactam, and 110
Keep at ℃ for 30 min. On the other hand, 0.28 g of sodium methylate was added to 30 g of molten ε-caprolactam, and the mixture was reacted at about 110° C., and the generated methanol was removed under reduced pressure to prepare an alkaline catalyst solution. below,
A polymerization test was conducted in the same manner as in Example 1. In this case, the concentration of hexathimelene diisocyanate relative to the total ε-caprolactam is 1/100 mol%,
The concentration of sodium caprolactam, which is an alkali catalyst, relative to the total ε-caprolactam was 1/100 mol%. Comparative Example 2 A polymerization test similar to Comparative Example 1 was conducted except that the concentration of sodium caprolactam based on the total ε-caprolactam was 1/200 mol %. Table 1 shows the results of each of the above examples and comparative examples.

[Table] Example 3 16.6 g of ethylene-ethyl acrylate copolymer (NUC6070, manufactured by Nippon Unicar, containing 8.5 mol% ethyl acrylate, MI250), polyoxypropylene diamine (Difurmine D-2000,
Manufactured by GFerson Chemical Co., molecular weight approx. 2000)
Introduce 522.5g into the three-necked flask No. 1, and
The reaction was carried out at 240° C. for 14 hours while stirring under reduced pressure of Hg. 12g of reaction mixture to 17g of ε-caprolactam
The mixture was dissolved at 110° C., 0.70 g of hexamethylene diisocyanate was added, and the mixture was reacted for about 30 minutes. On the other hand, 0.22 g of sodium methylate was added to 30 g of molten ε-caprolactam, and the mixture was reacted at about 110° C., and the generated methanol was removed under reduced pressure to prepare an alkaline catalyst solution. Thereafter, a polymerization test was conducted in the same manner as in Example 1. Note that the concentrations of the alkali catalyst and cocatalyst were both 1/100 mol % based on the total ε-caprolactam. The polymerization rate was 1 minute 10 seconds, the mold release time was 2 minutes 30 seconds, and the monomer content was 1.52 wt%. Example 4 500 g of substantially anhydrous ε-caprolactam was placed in a flask and dissolved at 110°C. 2.07 g of sodium methylate powder was added to this flask, and by-product methyl alcohol was removed under reduced pressure to prepare an alkaline catalyst solution. On the other hand, 200 g of the reaction mixture synthesized in Example 3 and 13.2 g of hexamethylene diisocyanate were added to 290 g of anhydrous ε-caprolactam kept at 110°C, and mixed uniformly.
The reaction was carried out at 110°C for 30 minutes. Next, the two were mixed and stirred, and the mixture was immediately poured into a bowl heated to 160°C.
It was placed in a mold with a size of 300 mm, width 300 mm, and thickness 20 mm, and then the mold was held in an oil bath at 160° C. for 15 minutes. It was very easy to take out the molded product from the mold. The impact strength (with notches) of the resulting molded product was 11.0 Kgcm/cm.

Claims (1)

[Claims] 1 ω-lactam is combined with (1) an alkali catalyst, (2) a polyfunctional cocatalyst, and (3) a repeating unit. (Here, R ¹ represents a hydrogen atom or a methyl group,
R ² represents a hydrogen atom or an alkyl group. l, m
are each an integer greater than or equal to 1. ) and a polyoxyalkylene diamine,
The copolymer (A) is polymerized in the presence of the reaction mixture (B) at a molar ratio of the group [formula] to the polyoxyalkylene diamine in a ratio of 1:20 to 5:1. A method for producing polyamide.