JP6277575B1 - Nylon production method and molded nylon by alkali polymerization method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing nylon by an alkali polymerization method, and a molded nylon having excellent mechanical strength inherent in nylon by an alkali polymerization method, improved brittleness, and easy to machine. SOLUTION: The nylon production method of the present invention comprises at least an ω-lactam, an alkaline lactam polymerization catalyst and an isocyanate having three isocyanate groups in the molecule, mixed and stirred, then poured into a heated mold and polymerized in the mold. This is a method for producing nylon by solidifying. The molded nylon of the present invention is a molded nylon in which at least ω-lactam is polymerized and solidified with an alkaline lactam polymerization catalyst and an isocyanate initiator having three isocyanate groups in the molecule. [Selection figure] None

Description

  The present invention relates to a method for producing nylon by alkaline polymerization of ω-lactam, and a molded nylon having improved machinability and acid resistance.

A method for producing nylon by polymerizing ω-lactam by the action of an alkaline lactam polymerization catalyst and an initiator is known as an alkali polymerization method for ω-lactam. Nylon obtained by this polymerization method is superior in mechanical strength such as tensile strength and bending strength, sliding properties, thermal properties, etc., compared to nylon for injection molding, which has a different manufacturing method. In particular, it is widely used as an industrial material such as automobile parts and machine parts.

Nylon obtained by the alkali polymerization method of ω-lactam (hereinafter referred to as “alkaline polymerization nylon”) is generally made by injecting a raw material mixture into a metal mold to produce a material such as a round bar, a plate material or a pipe. It is manufactured in the shape of For this reason, many of the various automotive parts and machine parts made of alkali polymerization nylon that are currently used are machined from materials (nylon materials) such as round bars, plates, and pipes manufactured by the alkali polymerization method. Is built.
Alkaline polymerized nylon is excellent in mechanical strength, but it is hard and brittle, and impact strength is not high, so when machining with a lathe or other processing equipment, the product may be chipped or the surface of the product may be damaged. It is known as a material difficult to machine. Therefore, advanced technology is required for machining the nylon material.

  Conventionally, there is no proposal regarding improvement of machinability of alkali polymerization nylon. Many proposals have been made regarding methods for improving the brittleness and impact properties of alkali-polymerized nylon. For example, Japanese Patent Laid-Open No. 58-152015 proposes an alkali polymerization nylon in which a flexible component such as polyoxyalkyleneamine is incorporated in the molecule. This nylon has improved impact characteristics and brittleness, and it is easy to produce a good machined product free from chipping even without a high level of processing technology. However, since this method has a flexible component in the molecule, there is a problem in that the mechanical strength of the alkali polymerization nylon is lowered and the original characteristics of the alkali polymerization nylon are lost.

JP 58-152015 A

  The present invention solves the above-mentioned problems, that is, the production of nylon by the alkali polymerization method, which retains the original excellent mechanical strength of the alkali-polymerized nylon, improves brittleness, impact strength, etc., and is easy to machine. It is an object to provide a method and molded nylon.

As a result of intensive studies on the alkali polymerization method of ω-lactam, the present inventors have used an isocyanate having three or more isocyanate groups in the molecule (hereinafter referred to as “triisocyanate”) as an initiator . The obtained alkali-polymerized nylon is improved in brittleness and impact properties without using a soft component as in Patent Document 1, and has no advanced technology without substantially reducing the original mechanical strength. However, the present inventors have found that a machined part free from defects such as chipping and roughening can be manufactured by a general-purpose lathe and other processing equipment, and reached the present invention.

(Nylon production method by alkali polymerization method)
The method for producing nylon by the alkali polymerization method of the present invention (hereinafter sometimes simply referred to as “the method for producing nylon of the present invention”) comprises at least ω-lactam, an alkaline lactam polymerization catalyst and hexamethylene diisocyanate trimer isocyanurate. , A mixture in which 0.1 to 1 mole of hexamethylene diisocyanate trimer isocyanurate is blended with respect to 1 mole of an alkaline lactam polymerization catalyst (excluding polyoxyalkylene polyamine) and then heated . injected within a method for obtaining a nylon is polymerized and solidified in the mold.

Another nylon production method of the present invention was heated after mixing and stirring an alkaline lactam polymerization catalyst, hexamethylene diisocyanate trimer isocyanurate, and an isocyanate having two isocyanate groups in the molecule. It is a method in which nylon is obtained by pouring into a mold and polymerizing and solidifying within the mold.

(Molded nylon)
In the molded nylon of the present invention, at least ω-lactam consists of an alkaline lactam polymerization catalyst and hexamethylene diisocyanate trimer isocyanurate, and hexamethylene diisocyanate trimer isocyanurate 0.1 mol per 1 mol of the alkaline lactam polymerization catalyst. Molded nylon formed by polymerizing and solidifying a mixture (but not including polyoxyalkylene polyamine) in which ˜1 mol is blended .

Another molded nylon of the present invention is the above-mentioned molded nylon , wherein an alkaline lactam polymerization catalyst, hexamethylene diisocyanate trimer isocyanurate and an isocyanate having two isocyanate groups in the molecule are mixed and stirred, and then heated in a mold. It is a molded nylon molded by polymerization.

  Nylon is known to have poor acid resistance, including conventional alkali polymerization nylon. For example, when nylon is immersed in high-concentration hydrochloric acid, sulfuric acid, formic acid or other acids, it dissolves in a short time. Molded nylon obtained by the nylon manufacturing method of the present invention has a longer shape than conventional alkali polymerization nylon when immersed in acids such as hydrochloric acid, sulfuric acid and formic acid, and has improved acid resistance. It became nylon. This suggests that the molecular weight of the molded nylon obtained by the nylon production method of the present invention is very large or has a crosslinked structure. This is considered that the molded nylon of the present invention has not only acid resistance but also improved brittleness and impact resistance, and is related to elimination of defects such as chipping and roughening during machining. The improved acid resistance of the molded nylon of the present invention is another effect of the present invention. Since the molded nylon of the present invention has a clear melting point, it is a thermoplastic polymer, and in the case of a crosslinked structure, it is considered to be a partial one that contributes to a certain degree of acid resistance.

The method for producing nylon by the alkali polymerization method of the present invention has the following effects.
(1) Since hexamethylene diisocyanate trimer isocyanurate is used as an initiator , brittleness and impact are improved without using a soft component, and the original mechanical strength is hardly reduced. Even without advanced technology, there is an effect that a machined part free from defects such as chipping and roughening can be produced by a general-purpose lathe and other machining equipment.
(2) Since hexamethylene diisocyanate trimer isocyanurate and an isocyanate having two isocyanate groups in the molecule are used as the initiator, the same effect as that of the nylon molding method can be obtained.

The molded nylon of the present invention has the following effects.
(1) Since no flexible components are used, the original mechanical strength is not reduced, brittleness and impact properties are improved, and it is possible to obtain a good machined product without advanced technology. It is.
(2) When immersed in acids such as hydrochloric acid, sulfuric acid and formic acid, the shape is maintained for a long time compared to conventional nylon, and the acid resistance is improved. Conventionally, it can be expected to be used in applications and fields where its use has been limited due to the difficulty in acid resistance.
(3) It is milky white, and when it is colored, the original color of the colorant can be colored.

[Nylon production method of the present invention]
The nylon production method of the present invention comprises at least ω-lactam, an alkaline lactam polymerization catalyst and an initiator hexamethylene diisocyanate trimer isocyanurate , mixed and stirred, then poured into a mold heated to a predetermined temperature, and polymerized in the mold. It is a method for producing molded nylon by solidifying.

[Ω-lactam]
Specific examples of ω-lactam used in the present invention include γ-butyrolactam, δ-valerolactam, ε-caprolactam, ω-capryllactam, ω-undecanolactam, ω-laurolactam and the like. These ω-lactams may be used alone or in combination of two or more. A preferred ω-lactam is ε-caprolactam alone or a mixture of ε-caprolactam and ω-laurolactam. The ω-lactam is used in advance with a water content of 0.2% by weight or less, preferably 0.1% by weight or less, by a dehydration treatment such as decompression. In the alkaline polymerization method of ω-lactam, since water adversely affects the polymerization reaction, it is preferable to manage not only the moisture in the raw material such as ω-lactam but also the humidity of the polymerization work environment below a predetermined value.

[Alkaline lactam polymerization catalyst]
As the alkaline lactam polymerization catalyst used in the present invention, a known catalyst compound used in the alkaline polymerization method of ω-lactam can be used. Specific examples include alkali metals, alkaline earth metals and their hydrides, oxides, alkylates, alkoxides, Grignard reagents, and reaction products of the above catalyst compounds with ω-lactams, such as ω-lactams. Sodium salt, and potassium salt of ω-lactam. Preferred alkaline lactam polymerization catalysts are ε-caprolactam sodium salt and ε-caprolactam potassium salt. The usage-amount of an alkaline lactam polymerization catalyst is 0.2-5 mol% with respect to 1 mol of omega-lactam, Preferably it is 0.4-2.5 mol%. Alkaline lactam polymerization catalyst is small, the polymerization reaction rate than the lower limit 0.2 mol% is slow, and if more than the upper limit 5 mol%, the low molecular weight in a mixture of ω- lactam and the alkaline lactam polymerization catalyst In some cases, the product may be formed, and the generated low molecular weight product may cause the polymerization reaction to become unstable and adversely affect the polymerized product.

[Initiator Example 1]
The initiator triisocyanate used in the present invention is an isocyanate having three isocyanate groups in the molecule. As the triisocyanate, there is a trimer of diisocyanates. Specific examples include hexamethylene diisocyanate trimer biuret, for example, duranate biuret represented by Chemical Formula 1 (trade name, Asahi Kasei Corporation), hexamethylene diisocyanate trimer isocyanurate, for example, duranate isocyanurate represented by Chemical Formula 2. (Asahi Kasei Co., Ltd. trade name), hexamethylene diisocyanate trimer adduct, for example, Duranate adduct represented by Chemical Formula 3 (Asahi Kasei Co., Ltd. trade name). Moreover, the reaction product of the said triisocyanate and (epsilon) -caprolactam can also be used. These triisocyanates may be used alone or in combination of two or more. Among these, hexamethylene diisocyanate trimer isocyanurate and a reaction product of ε-caprolactam and hexamethylene diisocyanate trimer isocyanurate are preferably used.

The amount of triisocyanate used is 0.1 to 1 mol, preferably 0.2 to 0.75 mol, with respect to 1 mol of the alkaline lactam polymerization catalyst. When the amount of triisocyanate used is more than the above upper limit of 1 mol, there is no change in the state during acid immersion, and the polymerization rate does not increase, so there is no point in increasing the amount. On the other hand, when the amount of triisocyanate used is less than the above lower limit of 0.1 mol, it may dissolve in a relatively short time by acid immersion, and the polymerization rate becomes slow.

[Initiator Example 2]
In the present invention, triisocyanate and a known diisocyanate having two isocyanate groups in the molecule can be mixed and used as an initiator. Specific examples of the diisocyanate that can be preferably used include hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, and a reaction product of the diisocyanate and ε-caprolactam, such as hexamethylene-1,6-biscarbamide caprolactam. When using a mixture of triisocyanate and diisocyanate, the triisocyanate is 30% by weight or more, preferably 50% by weight or more of the whole isocyanate. When the amount of triisocyanate is less than 30% by weight, when the obtained nylon is immersed in acids, it may dissolve in a relatively short time, which is not preferable.

[Alkali polymerization of ω-lactam]
The alkaline polymerization of ω-lactam in the present invention can be carried out by a known method. Hereinafter, an example using ε-caprolactam as ω-lactam will be described.
Prior to polymerization, ε-caprolactam is dehydrated and preferably has a water content of 0.1% by weight or less. As long as dehydration of ε-caprolactam can be dehydrated, there is no restriction on the dehydration method. Usually, after melt | dissolving (epsilon) -caprolactam, it depressurizes for a predetermined time. The water content in ε-caprolactam is measured by a Karl Fischer moisture meter or the like.

The alkaline lactam polymerization catalyst is prepared by adding and mixing a predetermined amount of the above-mentioned alkaline lactam polymerization catalyst into molten ε-caprolactam. When an alkaline lactam polymerization catalyst is mixed with ε-caprolactam, a by-product may be generated. In that case, the by-product is appropriately removed. For example, when an alkali metal is used as the alkaline lactam polymerization catalyst, generated hydrogen is removed. When an alkali metal alcoholate is used, the generated alcohol is removed. The ε-caprolactam mixed with the alkaline lactam polymerization catalyst is maintained at a temperature of 80 to 140 ° C., preferably 85 to 125 ° C. When the holding temperature is lower than the lower limit of 80 ° C., the polymerization reaction rate is slow, which is not preferable. When the upper limit is higher than 140 ° C., a low molecular weight product may be formed, which is not preferable because the low molecular weight product adversely affects the polymerization reaction.

The initiator triisocyanate may be directly added to and mixed in the ε-caprolactam melt mixed with the above-mentioned alkaline lactam polymerization catalyst, or a mixture of triisocyanate and ε-caprolactam You may mix with the epsilon caprolactam melt with which the alkaline lactam polymerization catalyst was mixed. In this case, the usage amounts of the alkaline lactam polymerization catalyst and triisocyanate are appropriately adjusted according to the amount of ε-caprolactam used. The initiator may be used by mixing triisocyanate and diisocyanate.

[Injection into mold]
A mixture comprising ε-caprolactam, an alkaline lactam polymerization catalyst and triisocyanate is immediately poured into a mold heated to a predetermined temperature after mixing and stirring, and a polymerization reaction proceeds in the mold to obtain molded nylon. Thus, the method of directly injecting a mixture of raw material ε-caprolactam, alkaline lactam polymerization catalyst, and triisocyanate into a mold to obtain a nylon molded product in the mold is a feature of the alkali polymerization method of ε-caprolactam. One. In the alkaline polymerization method of ε-caprolactam, the presence of moisture adversely affects the polymerization reaction, so all operations such as raw material adjustment, mixing, and injection into the mold are performed under an atmosphere of nitrogen gas or the like that reduces the influence of moisture. Is preferably carried out.

[Type]
As the mold used in the nylon production method of the present invention, a metal mold such as iron or stainless steel, or a resin mold such as silicone resin or epoxy resin can be used. Resin molds are unsuitable for mass production, but the mold production days are short, quick delivery and suitable for high-mix low-volume production. In the nylon production method of the present invention, a silicone resin mold is preferably used.

  As the silicone resin mold, for example, a silicone resin mold (Japanese Patent No. 5747138) previously developed by the present applicant can be used. Specifically, a kneaded resin molding die in which potassium octatitanate fiber or potassium hexatitanate fiber is kneaded in the silicone resin by about 15 to 45% by weight with respect to the silicone resin can be used. As the potassium titanate fiber, for example, Tismo of Otsuka Chemical Co., Ltd. can be used.

When injecting a mixture of ε-caprolactam, alkaline lactam polymerization catalyst and triisocyanate into the mold, the mold is heated to a temperature of 120 to 200 ° C, preferably 130 to 180 ° C. When the mold temperature is lower than the lower limit of 120 ° C., the polymerization reaction does not proceed sufficiently, which is not preferable. Further, when the mold temperature is higher than the upper limit of 200 ° C., a part of the nylon being polymerized may be melted during the polymerization reaction of the nylon obtained, which may lead to deterioration of the characteristics of the alkali polymerization nylon. Depending on the use amount and mold temperature of the alkaline lactam polymerization catalyst and triisocyanate, the alkali polymerization nylon of the present invention is 5 to 60 minutes after injecting a mixture of ε-caprolactam, alkaline lactam polymerization catalyst and triisocyanate into the mold. Later, the nylon molded product can be removed from the mold.

[Plasticizers, fillers, dyes, colorants, antioxidants, sheet materials]
In the nylon production method of the present invention, ε-caprolactam can be subjected to alkaline polymerization using a plasticizer, a filler, a dye, a colorant, an antioxidant, a sheet material, or the like that does not inhibit the polymerization reaction. Preferable plasticizers include N-alkylpyrrolidone and dialkylimidazolidinone. The amount used is 2 to 30% by weight with respect to ε-caprolactam.

[Filler, sheet material]
Specific examples of the filler include calcium carbonate, wollastonite, kaolin, graphite, gypsum, feldspar, mica, carbon black, molybdenum disulfide, and glass powder. Specific examples of the fiber include milled glass, glass fiber, fibrous magnesium compound, potassium titanate fiber, graphite fiber, boron fiber, carbon fiber, and steel fiber. The amount of these fillers and fibers used is 2 to 40% by weight with respect to ε-caprolactam. Examples of the sheet material include glass fiber cloth and carbon fiber cloth.

Hereinafter, the nylon manufacturing method of the present invention will be described using examples and comparative examples.
The bending strength and bending elastic modulus described in Examples and Comparative Examples are measured according to ASTM D-790, and the notched Izod impact value is measured according to ASTM D-256. Machinability was evaluated by changing the number of lathe rotation, bite shape, bite angle, and the like. In addition, the acid resistance was obtained by cutting the obtained nylon into a ribbon shape with a lathe or a milling machine, immersing 0.2 g of it in 20 cc of formic acid (concentration: about 90%) and allowing it to stand for visual observation.

[Example 1]
500 g of molten ε-caprolactam having a water content of 0.1% by weight or less was dehydrated and placed in a four-necked flask, and the temperature was adjusted to 110 ° C. After 5.0 g of sodium methylate powder was added to this flask, the methanol was reduced under reduced pressure until ε-caprolactam was refluxed, and a mixed solution of ε-caprolactam and an alkaline lactam polymerization catalyst (hereinafter referred to as “component A”). "). In another flask, 500 g of molten ε-caprolactam having a water content of 0.1% by weight or less was placed and adjusted to a temperature of 110 ° C. To this flask, 20.0 g of hexamethylene diisocyanate trimer isocyanurate was added and mixed by stirring to prepare a mixture of ε-caprolactam and hexamethylene diisocyanate trimer isocyanurate (hereinafter referred to as “component B”). . 100 g of A component and 100 g of B component are put in about 500cc container heated to about 100 ° C, and quickly stirred and mixed in a nitrogen gas atmosphere. It was poured into a mold and polymerized and solidified. After 10 minutes, the mold was opened, and a milky white ASTM test piece (molded nylon) was taken out. Bending strength of the resulting nylon 124M P a, a flexural modulus of 3300 m P a. The notched Izod impact value was 50 J / m. In addition, the sample immersed in formic acid was observed to swell even after one day, but retained its shape.

[Example 2]
A component and B component were adjusted in the same manner as in Example 1. In a container of about 1000 cc heated to about 100 ° C., 300 g of component A and 300 g of component B are placed in a nitrogen gas atmosphere. After stirring and mixing quickly, the mixture is immediately heated to 150 ° C. and made of silicone resin having a diameter of 100 mm The mixture was poured into a cylindrical mold having a height of about 70 mm and solidified by polymerization. After 15 minutes, a milky white cylindrical nylon molded product (molded nylon) was taken out of the mold. Using a lathe, the processability of this nylon molded product was evaluated. Chips were not found in the cut product, and the cut surface was good. In addition, the sample immersed in formic acid was observed to swell even after one day, but retained its shape.

[Comparative Example 1]
An ASTM test piece was obtained in the same manner as in Example 1 except that 10.0 g of hexamethylene diisocyanate was used instead of 20.0 g of hexamethylene diisocyanate trimer isocyanurate as the B component in Example 1. Bending strength of the obtained nylon 120M P a, a flexural modulus of 3260M P a. The notched Izod impact value was 45 J / m. Further, the sample immersed in formic acid was deformed after 1 hour and dissolved after 1 hour 30 minutes.

[Comparative Example 2]
In Example 2, the same procedure as in Example 2 was used except that 10.0 g of hexamethylene diisocyanate was used instead of 20.0 g of the hexamethylene diisocyanate trimer isocyanurate of component B, and a cylindrical nylon molded product was obtained. It was.
In the evaluation of workability on a lathe, chipping may occur in a cut product depending on the processing conditions, and smoothness may be deteriorated at a part of the cut surface. Further, the sample immersed in formic acid was deformed after 1 hour and dissolved after 1 hour 30 minutes.

[Example 3]
Example 1 was the same as Example 1 except that 17.0 g of hexamethylene diisocyanate trimer isocyanurate and 5.0 g of hexamethylene diisocyanate were used in place of 20.0 g of hexamethylene diisocyanate trimer isocyanurate as component B. The ASTM test piece was obtained. Flexural strength of nylon 120M P a, the flexural modulus 3340M P a, notched Izod impact value was 47J / m. In addition, the sample immersed in formic acid was observed to swell even after one day, but retained its shape.

[Molded nylon of the present invention]
The molded nylon of the present invention is the nylon produced in any of the above embodiments, and at least ω-lactam is polymerized in the mold by an alkaline lactam polymerization catalyst and an isocyanate initiator having three isocyanate groups in the molecule. Solidified nylon.

  Another nylon of the present invention is a nylon produced in any of the above embodiments, and includes at least ω-lactam, an alkaline lactam polymerization catalyst, an isocyanate having three isocyanate groups in the molecule, and two in the molecule. Nylon polymerized and solidified in a mold containing an isocyanate initiator having an isocyanate group.

  The molded nylon of the present invention is milky white when a coloring agent, a plasticizer, a filler, a dye, a coloring agent, an antioxidant, or a coloring material is not used.

  The molded nylon produced by the nylon production method of the present invention is excellent in mechanical strength and has good machinability, and is therefore used as a machined product in the field of various parts of automobile parts and machine parts. In addition, because of improved acid resistance, product development is expected in fields where conventional nylon cannot be used.

Claims (5)

In the manufacturing method of nylon,
A mixture comprising at least ω-lactam, an alkaline lactam polymerization catalyst and hexamethylene diisocyanate trimer isocyanurate, and 0.1 to 1 mol of hexamethylene diisocyanate trimer isocyanurate per 1 mol of the alkaline lactam polymerization catalyst. (However, no polyoxyalkylene polyamines.) was injected after stirring, the the heated mold, to produce nylon by polymerizing solidify within the mold,
A method for producing nylon by an alkali polymerization method. In the manufacturing method of nylon of Claim 1 ,
After mixing and stirring the isocyanate having two isocyanate groups in the alkaline lactam polymerization catalyst, hexamethylene diisocyanate trimer isocyanurate and the molecule was injected into the heated inside the mold, producing nylon by polymerizing solidify within the mold To
A method for producing nylon by an alkali polymerization method. In the nylon manufacturing method by the alkali polymerization method of Claim 1 or Claim 2,
Hexamethylene diisocyanate trimer isocyanurate is used in an amount of 30% by weight or more of the total isocyanate compound,
A method for producing nylon by an alkali polymerization method. In molded nylon,
A mixture comprising at least ω-lactam , an alkaline lactam polymerization catalyst and hexamethylene diisocyanate trimer isocyanurate, and 0.1 to 1 mol of hexamethylene diisocyanate trimer isocyanurate per 1 mol of the alkaline lactam polymerization catalyst. (However, polyoxyalkylene polyamine is not included.) Was polymerized and solidified in a heated mold .
Molded nylon characterized by that. The molded nylon according to claim 4,
An alkaline lactam polymerization catalyst, hexamethylene diisocyanate trimer isocyanurate and an isocyanate having two isocyanate groups in the molecule were mixed and stirred, and then polymerized and solidified in a heated mold .
Molded nylon characterized by that.