JPH06145345A - Production of polyamide resin - Google Patents

Abstract

PURPOSE:To obtain a polyamide resin excellent in mechanical properties, esp. low-temp. bending resistance, and in moldability. CONSTITUTION:Raw materials for a polyamide resin are reacted in the presence of a 7-23C monocarboxylic acid and a 6-22C monoamine and/or a 2-22C diamine or in the presence of a 6-22C monoamine and a 3-24C dicarboxylic acid in an amt. of the sum of the carboxyl and amino groups of these compds. (based on 1mol of repeating structural units of the resulting resin) of 3-20 milliequivalents under such a condition that the pressure at the end of the reaction is 400Torr or lower. Thus, a polyamide resin for injection molding is produced of which 55-100% of the molecular ends are 6-22C hydrocarbon groups and which has a relative viscosity (in 98% sulfuric acid in a concn. of 1% at 25 deg.C according to JIS K 6810) of 2.0-2.5.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a polyamide resin. Specifically, it relates to a method for producing a polyamide resin having excellent mechanical properties and moldability.

[0002]

BACKGROUND OF THE INVENTION Polyamide resins are widely used as engineering plastics because of their excellent mechanical properties, but their bending resistance, especially at low temperatures, is still desired to be improved. ing.

[0003]

Means for Solving the Problems As a result of intensive studies on the improvement of mechanical properties of a polyamide resin, the present inventors have found that a polyamide resin having a specific relative viscosity having a specific hydrocarbon group as an end group is It has been found that mechanical properties, especially at low temperatures, have excellent bending and tensile strength, as well as excellent melt flowability and releasability, and that this polyamide resin is blended with a polyamide resin whose terminal groups have not been modified. In the case of the present invention, it is possible to obtain a resin composition having excellent properties described above, and it is known that the resin composition has good compatibility with polyolefin resins such as polyethylene, polypropylene, polybutadiene, polyisobutylene and polystyrene. Was completed.

That is, the object of the present invention is to provide a polyamide resin of great industrial value,
The gist of the invention is to use a polyamide raw material as a total amount of milliequivalents of a carboxyl group and an amino group with respect to 1 mol of a raw material monomer constituting a repeating unit or 1 mol of the raw material monomer unit, and a monocarboxylic acid having 7 to 23 carbon atoms and 3 to 20 meq / mol. And carbon number 6 to 2
In the presence of a monoamine having 2 carbon atoms and / or a diamine having 2 to 22 carbon atoms, or a monoamine having 6 to 22 carbon atoms and a dicarboxylic acid having 3 to 24 carbon atoms, the pressure at the end of the reaction is polymerized at 400 Torr or less. A polyamide having a hydrocarbon group having 6 to 22 carbon atoms at the end, (a) the number of the hydrocarbon groups is 55 to 100% of the number of all the terminal groups of the polyamide, and (b) according to JIS K6810. It exists in a method for producing a polyamide resin for injection molding, which has a relative viscosity of 2 or more and less than 2.5 measured at a temperature of 25 ° C. in a 98% sulfuric acid concentration of 1%.

The polyamide referred to in the present invention is a polyamide obtained by polycondensation of a lactam having three or more membered rings, a polymerizable ω-amino acid, or a dibasic acid and a diamine. As a raw material of these polyamides, specifically, ε
Lactams such as caprolactam, enanthlactam, capryllactam, lauryllactam, α-pyrrolidone, α-piperidone, 6-aminocaproic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, ω such as 11-aminoundecanoic acid -Amino acids, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecadioic acid, hexadecadioic acid, hexadecenedioic acid, eicosandioic acid, eicosadiendioic acid, di Glycolic acid, 2,
Dibasic acids such as 2,4-trimethyladipic acid, xylylenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid and isophthalic acid, hexamethylenediamine, tetramethylenediamine, nonamethylenediamine, undecamethylenediamine, Examples include didecamethylenediamine, 2,2,4 (or 2,4,4) -trimethylhexamethylenediamine, bis- (4,4′-aminocyclohexyl) methane, and diamines such as metaxylylenediamine.

Examples of the hydrocarbon group having 6 to 22 carbon atoms at the end of the polyamide of the present invention include hexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, undecyl group, dodecyl group and tridecyl group. Group, tetradecyl group, tetradecylene group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, octadecylene group, eicosyl group, aliphatic hydrocarbon group such as docosyl group, cyclohexyl group, methylcyclohexyl group, cyclohexylmethyl group Examples thereof include alicyclic hydrocarbon groups, phenyl groups, toluyl groups, benzyl groups, aromatic hydrocarbon groups such as β-phenylethyl groups, and the like.

These hydrocarbon groups are introduced during the production of the polyamide by using the carboxylic acids and amines mentioned below. As the terminal group of the polyamide, in addition to the above hydrocarbon group, there are an amino group and a carboxyl group derived from the above-mentioned polyamide raw material. The hydrocarbon group is measured by gas chromatography after hydrolyzing the polyamide with hydrochloric acid. The amino group is measured by dissolving polyamide in phenol and titrating with 0.05N hydrochloric acid. The carboxyl group is measured by dissolving polyamide in benzyl alcohol and titrating with 0.1N caustic soda.

The number of all terminal groups is the sum of the numbers of the above hydrocarbon groups, amino groups and carboxyl groups. In the present invention, the number of hydrocarbon groups is 55 to 10 of the total number of terminal groups.
It is 0%. If the number is too small, the melt fluidity is lowered and the bending resistance and the tensile strength are also lowered, which is not preferable. Further, it is preferable from the viewpoint of the physical properties of the polyamide resin to make the hydrocarbon group close to 100% of the number of all terminal groups, but since it becomes difficult to manufacture it, industrially, it is 55 to 95%. It is good to set the range.

The relative viscosity of the polyamide resin of the present invention is J
According to IS K6810, the concentration measured in 98% sulfuric acid at 1% and a temperature of 25 ° C. is 2 or more and less than 2.5, preferably 2.2 or more and less than 2.5. If the relative viscosity is low, improvement in fatigue resistance cannot be expected. On the contrary, if it is too high, the melt fluidity is impaired, which is not preferable. In order to produce the polyamide resin of the present invention, the above-mentioned polyamide raw material is used in an amount of 3 to 20 meq / mol as a total amount of milliequivalents of a carboxyl group and an amino group with respect to 1 mole of a raw material monomer constituting a repeating unit or a raw material monomer unit.
C7-23 monocarboxylic acid and C6-2
Polycondensation is carried out in the presence of a monoamine having 2 carbon atoms and / or a diamine having 2 to 22 carbon atoms, or a monoamine having 6 to 22 carbon atoms and a dicarboxylic acid having 3 to 24 carbon atoms.

Examples of the monocarboxylic acid having 7 to 23 carbon atoms include enanthic acid, caprylic acid, capric acid, pelargonic acid, undecanoic acid, lauric acid, tridecanoic acid,
Aliphatic monocarboxylic acids such as myristic acid, myristoleic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, arachidic acid, behenic acid, alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid, methylcyclohexanecarboxylic acid , Benzoic acid, toluic acid, ethylbenzoic acid, aromatic monocarboxylic acids such as phenylacetic acid, and the like. Corresponding derivatives, such as acid anhydrides, esters, amides, etc., which can play the same role as the above-mentioned acids in the reaction for producing polyamide can also be used.

As the monoamine having 6 to 22 carbon atoms, hexylamine, heptylamine, octylamine, 2-
Ethylhexylamine, nonylamine, decylamine,
Of undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecylamine, octadecylamine, octadecyleneamine, eicosylamine, aliphatic monoamines such as docosylamine, cyclohexylamine, methylcyclohexylamine Examples thereof include alicyclic monoamines, benzylamine, aromatic monoamines such as β-phenylethylamine, and the like.

The diamines having 2 to 22 carbon atoms include ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, and unamine. Decamethylenediamine, dodecamethylenediamine, tridecamethylenediamine, hexadecamethylenediamine, octadecamethylenediamine, 2,2,4
Aliphatic diamines such as (or 2,4,4) -trimethylhexamethylenediamine, cyclohexanediamine, methylcyclohexanediamine, bis- (4,4 '
Examples thereof include alicyclic diamines such as -aminocyclohexyl) methane and aromatic diamines such as xylylenediamine.

Examples of the dicarboxylic acid having 3 to 24 carbon atoms include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, tridecadioic acid. , Tetradecadioic acid, hexadecadioic acid,
Hexadecenedionic acid, octadecadionic acid, octadecenedionic acid, eicosandioic acid, eicosendioic acid, docosandionic acid, aliphatic dicarboxylic acids such as 2,2,4-trimethyladipic acid, 1,4-cyclohexanedicarboxylic acid Examples thereof include alicyclic dicarboxylic acids such as acids, terephthalic acid, isophthalic acid, phthalic acid, and aromatic dicarboxylic acids such as xylylenedicarboxylic acid.

The reaction for producing the polyamide resin of the present invention may be carried out by using the above-mentioned polyamide raw material and initiating the reaction according to a conventional method. The above-mentioned carboxylic acid and amine are optional from the start of the reaction to the start of the reaction under reduced pressure. Can be added at the stage of. The carboxylic acid and amine may be added simultaneously or separately. The amount of carboxylic acid and amine used is, as the amount of the carboxyl group and amino group thereof, 3 to 20 per 1 mol of the raw material monomer constituting the repeating unit or the raw material monomer unit, respectively.
It is meq / mol, preferably 4 to 19 meq / mol. Here, the equivalent of the amino group is one equivalent to the amount when 1 mol of the amide group is produced by reacting with 1 equivalent of the carboxyl group in a ratio of 1: 1.

If this amount is too small, it becomes impossible to produce a polyamide resin having the effects of the present invention. On the other hand, if the amount is too large, it becomes difficult to produce a polyamide having a high viscosity, and the physical properties of the polyamide resin are adversely affected. The polyamide resin of the present invention has a hydrocarbon group as a terminal group, and has a relative viscosity of 2 or more. In order to produce such a polyamide resin, it is necessary to carry out the reaction at 400 Torr or less at the end of the reaction, and in this case as well, the relationship between the amount of the terminal terminator and the degree of reduced pressure is set so that ηrel falls within the range of 2 to 2.5. Must be considered. If the pressure at the end of the reaction is high, the desired relative viscosity and end termination rate cannot be obtained. Low pressure is not a disadvantage.

The reduced pressure reaction time is 0.5 hours or more, usually 1.
~ 2 hours is recommended. Further, when the polyamide resin of the present invention is blended with, for example, an unmodified polyamide resin, a more excellent resin composition can be obtained, and the blend ratio (weight ratio) at that time is that the polyamide / blend of the present invention = 10/90 to 95/5, preferably 20/80
~ 80/20.

[0017]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Example 1 and Comparative Examples 1-2 In a 200 liter autoclave, 60 kg of ε-caprolactam, 1.2 kg of water, 672 g of stearic acid.
(4.40 meq / mol) and 639 g (4.40 meq / mol) of octadecylamine were charged, sealed in a nitrogen atmosphere, heated to 250 ° C., reacted under pressure for 2 hours with stirring, and then gradually released. Press to 200 Torr
Then, the pressure was reduced to 2, and the reaction was performed under reduced pressure for 2 hours.

After introducing nitrogen and returning the pressure to normal pressure, stirring was stopped and the strands were extracted to form chips, and unreacted monomers were extracted and removed using boiling water and dried. The obtained chips were put into a 3.6 ounce injection molding machine (manufactured by Toshiba Machine Co., Ltd.,
IS-75S type), width 10 mm, thickness 2 mm, length 1
Using a mold for molding test pieces of 00 mm, resin temperature 250
℃, mold temperature 80 ℃, injection time 5 seconds, cooling time 10 seconds,
Specimens for tensile and bending tests were molded with a total cycle of 18 seconds.

The melt fluidity is indicated by the injection pressure at that time. The tensile test was carried out by pulling with a force of 5 kg at an instant at a temperature of −10 ° C. and counting the number of broken pieces out of 20 pieces. The bending test is performed by bending a test piece at a temperature of -10 ° C by 180 ° and
The number of broken pieces was counted. The mold releasability is, apart from the above molding, using a mold capable of forming a lattice in which ribs of 5 mm × 4 mm are arranged at 15 mm intervals in a frame of 80 mm × 80 mm,
Resin temperature 250 ℃, mold temperature 80 ℃, injection time: 5 seconds,
Continuous injection molding was performed with a cooling time of 12 seconds and a total cycle of 20 seconds, and the number of shots until the release defect occurred was counted. ○ indicates that continuous molding was possible for 25 or more shots. × indicates that mold release failure occurred in 10 shots or less. △ indicates that mold release failure occurred between 10 and 25 shots.

The terminator termination rate is the ratio of hydrocarbon groups to the total number of terminal groups of the polyamide, and is measured by gas chromatography after hydrolyzing the polyamide with hydrochloric acid. The results are shown in Table 1 below.

For comparison, acetic acid 1.13 meq was used without using stearic acid and octadecylamine.
/ Mol and the final reaction pressure was set to 500 Torr, the result when the same operation as in Example 1 was carried out (Comparative Example 1), and the relative viscosity was the same as in Example 1 and the terminal termination rate was 52%. The result (Comparative Example 2) of the same polyamide as in Example 1 is also shown.

[0023]

[Table 1]

Examples 2-6 A 200 l autoclave was charged with ε-caprolactam 60.
kg, 1.2 kg of water and carboxylic acid and amine shown in Table 2 below were charged, and a polymerization reaction was carried out in the same manner as in Example 1 to give a polyamide resin described in the column "Polyamide of the present invention" in Table 2. Was manufactured.

This polyamide resin and the polyamide of Comparative Example 1 were mixed at the blending ratio (weight ratio) shown in the "Blend" column of Table 2 below, and injection molding was carried out in the same manner as in Example 1 to conduct a test. It was The results are shown in Table 2 below.

[0026]

[Table 2]

[0027]

The polyamide resin obtained by the method of the present invention is excellent in various properties such as bending resistance, tensile strength, melt flowability and mold release property, and the terminal group is not modified. It has excellent melt fluidity when melt-mixed with, so it can be used for various industries such as injection molding, extrusion molding, compression molding, etc. It can be molded into a container, a film, a sheet, a tube or a filament for a three-dimensional molded article suitable as a member and for packaging foods, pharmaceuticals, industrial chemicals, cosmetics and the like, and is industrially very useful.

Claims (1)

[Claims] 1. A polyamide raw material, as a total amount of milliequivalents of a carboxyl group and an amino group with respect to 1 mol of a raw material monomer constituting a repeating unit or 1 mol of the raw material monomer unit, a monocarboxylic acid having 3 to 20 meq / mol and 7 to 23 carbon atoms. Acid and 6 to 2 carbon atoms
In the presence of a monoamine having 2 carbon atoms and / or a diamine having 2 to 22 carbon atoms, or a monoamine having 6 to 22 carbon atoms and a dicarboxylic acid having 3 to 24 carbon atoms, the pressure at the end of the reaction is polymerized at 400 Torr or less. A polyamide having a hydrocarbon group having 6 to 22 carbon atoms at the end, (a) the number of the hydrocarbon groups is 55 to 100% of the number of all the terminal groups of the polyamide, and (b) according to JIS K6810. A method for producing a polyamide resin for injection molding, having a relative viscosity of 2% or more and less than 2.5, measured at a concentration of 1% in 98% sulfuric acid and a temperature of 25 ° C.