JPS62252426A - Production of nylon 6 - Google Patents

Abstract

PURPOSE:To facilitate the production of nylon 6 of a desired crystalline structure (alpha or gamma-form), by polymerizing a monomer for nylon 6 in the presence of a silicate at a temperature higher than the melting point of the monomer and cooling the product at a specified cooling rate. CONSTITUTION:100pts.wt. monomer (A) for nylon 6 (e.g., caprolactam) is polymerized in the presence of 0.001-100pts.wt. silicate (B) (e.g., montmorillonite), desirably, swollen with an organic substance (e.g., 12-aminododecanoic acid hydrochloride) at a temperature higher than the melting point of component A (about 220 deg.C), and the product is cooled at a cooling rate <=4 deg.C/min from the melting point or above to 160 deg.C or below to obtain a composite of nylon 6 of an alpha crystalline structure with the silicate or cooled at a cooling rate >=10 deg.C/min to obtain a composite of nylon of a gamma crystalline structure. This composite is dissolved in a solvent (e.g., m-cresol), and the silicate is removed to obtain nylon of an alpha or gamma crystalline structure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing nylon 6 having a desired a-type or r-type crystal structure.

[Conventional technology]

Nylon 6 has a position as a representative engineering glass due to its well-balanced properties, and demand is expected to continue to grow, especially in the automobile industry.

Nylon 6 is a crystalline polymer and therefore exhibits excellent properties in terms of tensile strength and rigidity, but on the other hand, it does not have a sufficient impact strength for use in automobile exterior panels and the like. Nylon 6, which is produced using a rapid alkali-catalyzed polymerization method that is especially suitable for large parts, is said to have a lower impact strength than nylon 6 produced using other hydrolytic polymerization methods.
“Nylon Plastics,” edited by M. I. Cohan (ed.
NyIon Plastics), P 457
,in! -Interscience
, 1973).

Improving the brush strength of nylon 6 is one of the central issues in the nylon industry, and attempts have been made to improve it by blending it with elastomers or collaborating with it (for example,
-5809, Special Publication No. 54-40120). However, these methods inevitably result in amorphous or low crystallization of nylon 6.

The crystal structures of nylon 6 are known as the a-type with a planar zigzag structure and the γ-type with a spiral structure.A-type nylon 6 has a high melting point and high density, and R-type nylon 6 has a low melting point and It has a density that is intermediate between a-type crystal and amorphous.

Therefore, the usefulness of nylon 6 is further increased by using the a-type nylon 6 for members that require more uniformity and the γ crystal for members requiring more impact strength. For this reason, it is desired to manufacture nylon 6 separately into a-type or γ-type.

However, nylon 6 obtained by conventional methods is only the α type, which is considered to be the most stable type, and the γ type is made from the a type by special treatments such as iodine treatment (I,
, E. Alexander, “X-ray diffraction of polymers”, Kagaku Dojin, 1973).

In order to solve the above problems, the inventors of the present invention have conducted intensive studies and have completed the present invention.

[Purpose of the invention]

The present invention aims to provide a method for easily producing nylon 6 having a desired crystal structure of either mam or gamma type.

[Structure of the invention]

The present invention involves a polymerization process in which a polymer of nylon 6 is placed on a table at a temperature below its melting temperature in the presence of a silica salt, and a cooling rate is controlled to convert the nylon 6 from above its melting temperature to 160%.
This is a method for producing nylon 6 characterized by comprising a cooling step of cooling to below .degree.

Hereinafter, the configuration of the present invention will be explained in more detail.

In the present invention, it is believed that by controlling the presence of silicate in the polymerization step and the cooling rate in the cooling step, it is possible to produce nylon 6 having a desired crystal structure of either the a-type or the γ-type.

Examples of the silicate include montmorillonite, vermiculite, heloysite, etc., and one or more of these may be used.

In addition, in order to uniformly disperse the silicate in the nylon 6 monomer, it is preferable to swell it with an organic substance in advance. The organic matter may contain hydrocarbons, amines,
Carboxylic acid, alcohol.

Any compound such as a halide may be used, but a compound having an onium ion in its molecule that forms a strong chemical bond with a silicate through a cation exchange reaction is desirable. Specific examples of the organic substances include trimethylamine, triethylamine, hexylamine, cyclohexylamine, dodecylamine, ethylenediamine, hexamethylenediamine, hexamethylenetetramine, polyallylamine, and pyridine.

Aniline, benzylamine, bis(aminomethylv)benzene, aminophenol, alanine, 4-aminobutyric acid, 6-aminocaproic acid, 12-aminododecanoic acid, 1
Examples include strong acid salts such as 6-amitsuhexadecanoic acid,
It is not limited to these. The strong acid used here is hydrochloric acid.

Examples include hydrobromic acid, sulfuric acid, phosphoric acid, and the like. However,
The above organic substances may be used alone or in combination of two or more.

The amount of the silicate added (the amount present in the polymerization process) is
1001 to 100 parts by weight of nylon 6
It is preferably within the range of 100 parts by weight.

If the amount added is less than 1001 parts by weight, a mixture of a-type and γ-type is likely to be produced. If the amount exceeds 100 parts by weight, the viscosity of the reaction mixture may become high and the reaction rate may decrease. More preferably, it is within the range of 1 lL01 to 50 parts by weight.

The nylon 60 polymerization method is an existing method.

For example, any method such as hydrolysis polymerization of cabrolactam, alkali-catalyzed polymerization of caprolactam, dehydration polymerization of 6-aminocaproic acid, etc. may be used.

Further, the polymerization temperature is set to be higher than the melting temperature of nylon 6. Generally, its melting temperature is about 220°C. This is because if the temperature is lower than the melting temperature of nylon 6, crystal precipitation occurs during the polymerization reaction, and crystal precipitation cannot be achieved by controlling the cooling rate in the present invention.

In addition, as monomers for nylon 6, cabroladum,
6-Aminocaproic acid, etc. are used in one of these or 2a1 or more.

In addition, in one polymerization step, additives 1 that do not substantially inhibit the polymerization reaction, such as glass fibers, IIi additives, antioxidants, etc., may be present.

In the cooling step, the polymerized nylon 6 is cooled from above its melting temperature to below 160°C.

At this time, by controlling the cooling rate, nylon 6 having either an α-type or a γ-type crystal structure is produced. Note that if the control of the cooling rate is stopped before the temperature reaches 160°C, nylon 6 with the desired crystal structure cannot be obtained.

The cooling rate is controlled at a cooling rate of 4°C/min or less when producing α-type nylon 6, and at a cooling rate of 10°C/min or more when producing r-type nylon 6. Do by doing.

In other words, in the case of slow cooling of 4°C/min or less, 90
% or more of α-type nylon 6 is formed.

In this case, it is desirable that the lower limit of the cooling rate be α1°C/min; if it is slower than 1L1°C/min, cooling will take more than 24 hours and there will be little economic benefit. In this cooling method, the reactor in which nylon 6 was polymerized was immersed in an oil bath after polymerization.

There are methods such as leaving it to the natural heat dissipation of the oil. Mayu.

The cooling process may be precisely programmed for slow cooling.

Further, in the case of rapid cooling at 10° C./min or more, 90% or more of γ-type nylon 6 is formed. Note that it is practical and desirable that the upper limit of the cooling rate in this case is 900° C./min. As for this cooling method, after piling up the reactor molded with nylon 6, it is taken out from a heating device such as an oil path and air cooled at room temperature. (B) Cooling with ice water from the outside of the reactor (q Cooling with liquid nitrogen from the outside of the reactor. Alternatively, there are methods such as injecting nylon 6 in a zero molten state into water. You can program it to cool down quickly.

Nylon 6 obtained by the present invention may be obtained as a composite of nylon 6 and silicate depending on the amount of silicate added. As previously proposed by the present inventors (Japanese Patent Application No. 60-217396), this composite is a composite of nylon 6 and silicate at the molecular level and has excellent mechanical strength and heat resistance. Yes, it can be used effectively. Further, only silicate can be easily removed from the composite by dissolving nylon 6 with a solvent such as 9m-cresol or 1m-cresol formic acid/chloroform.

〔Effect of the invention〕

According to the present invention, nylon 6 having a desired am or γ crystal structure can be easily produced. Although the mechanism by which this effect of the present invention is obtained is not clear, it is thought to be due to the presence of silicate in the polymerization step of the present invention and the control of the cooling rate in the cooling step.

〔Example〕

The present invention will be explained in detail below.

Example 1 100f of montmorillonite (Kunimine Kogyo - trial production, trade name [Kunibia FJ) was dispersed in 101% of water, and 5% of the water was dispersed.
After adding 1.2'l of 12-aminododecanoic acid and 24ml of concentrated hydrochloric acid and stirring for 5 minutes.

- Past nine. Furthermore, this was thoroughly washed and then vacuum dried. In this way, montmorillonite (abbreviated as 12-M) swollen with 12-aminododecanoic acid hydrochloride was prepared.

Next, put 10of of cabrotam and the above 12-M of α2f into a reactor equipped with a stirrer, and heat the mixture to 100°C in an oil bath.
A highly viscous homogeneous dispersion was obtained. To this was added 2.42 liters of sulfur hydride, and the temperature was then raised to 250° C. in an oil path, then 1.37 F of N-acetyl carbloctam was added, and heating was continued for 30 minutes. Thereafter, one reactor was taken out of the oil path and cooled externally with ice water.

When the interplanar spacing d was measured using X-ray diffraction method, 4.2 peaks were assigned to r-type, but 4 and 4 peaks were assigned to a-type.
A and 58m peaks were not observed at all.

It was essentially r-type.

Example 2 A polymerization step was carried out in the same manner as in Example 1 to polymerize Su5Iron6, and even after the heating was stopped, the reactor was slowly cooled in an oil path. This slow cooling is carried out from 2.8 to [15
The cooling rate was set at °C/min.

When the interplanar spacing d of the obtained nylon 6 was measured in the same manner as in Example 1, peaks of 4.4 mm and 581 were obtained, and 9, but no peak of 42 was observed, and substantially
I failed.

Comparative Example 1° except that the reactor was heated using a mantle heater connected to a program temperature controller.

The polymerization step was carried out in the same manner as in Example 1. Next 5℃/
It was cooled to 100° C. at a cooling rate of 100 min.

The surface spacing dft of the obtained nylon 6 was measured in the same manner as in Example 1, and the results were 4.4 A and 4.2.
The peaks of X and 58λ were observed with equal intensity. Calculation from the ratio of the peak areas of each crystal type revealed that this nylon 6 contained a mixture of α type and r type at a ratio of 60:40.

Comparative Example 2 12-M in Example 1 was not used, and the rest were as in Example 1.
Polymerize nylon 60 in the same manner as above.

A cooling process was performed, and the interplanar spacing d was measured.

As a result, a peak with a difference of 5-8 from 44 was not obtained.

A peak with a difference of 42 was obtained, indicating that the nylon 6 was essentially a-type.

The measurement results of Examples 1 and 2 and Comparative Example 1.2 are shown in the table.

As is clear from the table, α-type or r-type
It is found that nylon 6 can be produced with any desired crystal structure.

table pin applicant Toyota Central Research Institute Co., Ltd.

Claims (3)

[Claims] (1) A polymerization step in which nylon 6 monomer is polymerized at a temperature above its melting temperature in the presence of a silicate, and a cooling step in which the nylon 6 is cooled from above the melting temperature to below 160°C by controlling the cooling rate. A method for producing nylon 6, characterized by comprising: (2) In the cooling step, nylon 6 having an α-type crystal structure is produced by cooling nylon 6 from the melting temperature or higher to 160°C or lower at a cooling rate of 4°C/min or less. 1) The method for producing nylon 6 as described in section 1). (3) In the cooling step, nylon 6 having a γ-type crystal structure is produced by cooling nylon 6 from the melting temperature or higher to 160°C or lower at a cooling rate of 10°C/min or more. 1) The method for producing nylon 6 as described in section 1).