JPH0757798B2 - Polyamide resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a polyamide resin, and more specifically to a polyamide resin having reduced water absorption.

(Prior Art) Polyamide resins are widely used as engineering plastics because of their excellent mechanical properties. These polyamide resins further have a hydrocarbon group at the terminal in order to improve the bending resistance (JP-A-61-
No. 163935), and in order to improve resistance to moist heat, a copolyamide having a hydrocarbon group at the terminal is used (JP-A-62-148527), and various improvements have been added.

(Problems to be Solved by the Invention) However, since the polyamide resin has an amide group in its structure, it generally has good affinity with water and easily absorbs water. That is, since the amide group can incorporate a water molecule by hydrogen bond, the polyamide resin exhibits water absorption.

Such a water-absorbing polyamide resin has problems that it absorbs water during its manufacturing and processing steps, resulting in a dimensional change in the product and a decrease in mechanical strength.

[Structure of the Invention] (Means for Solving the Problems) The inventors of the present invention have conducted extensive studies to reduce the water absorption of a polyamide resin, and as a result, have found that a hydrocarbon group having a hydroxyphenyl group at the end of the polyamide is It has been found that the water absorption can be greatly reduced by disposing it, and the present invention has been completed.

That is, the polyamide resin of the present invention has the following formula at the terminal: (In the formula, m and n represent integers satisfying 2 ≦ m + n ≦ 22; ^one of R ¹ and R ² is And the other represents a hydrogen atom), and has a hydrocarbon group having a hydroxyphenyl group.

In the present invention, the polyamide is not particularly limited, and examples thereof include polyamides obtained from amino acids, lactams or diamines, and dicarboxylic acids.

Among the monomers that are raw materials for the polyamide used in the present invention, examples of amino acids include 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, p-aminomethylbenzoic acid, and the like. , As lactam, for example, ε-caprolactam, ε
-Laurolactam and the like can be mentioned. As the diamine, tetramethylenediamine, hexamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, m-xylylenediamine , P-xylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1-amino-3-aminomethyl-
3,5,5-Trimethylcyclohexane, bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, 2,2-bis ( 4-aminocyclohexyl) propane, bis (aminopropyl) piperazine, aminoethylpiperazine and the like can be mentioned. Examples of the dicarboxylic acid include adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5- Examples thereof include sodium sulfoisophthalic acid and diglycolic acid.

In addition, a copolyamide obtained by combining the above-mentioned amino acid, lactam, diamine, dicarboxylic acid and the like, which is a monomer component as a raw material for polyamide, can be mentioned.

The present invention is characterized in that a hydrocarbon group having a hydroxyphenyl group represented by the above formula is arranged at the terminal of the above-mentioned polyamide, and as the hydrocarbon group having such a hydroxyphenyl group, for example, , An alkyl group in which any hydrogen atom is substituted with a hydroxyphenyl group,
For example, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group,
Examples thereof include dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group (stearyl group), and these groups are bonded to the terminal amino group of polyamide by an amide bond.

The hydroxyphenyl group may be at any position of the above hydrocarbon group, and the hydroxy group may be at any position of the phenyl group.

The hydrocarbon group having a hydroxyphenyl group is preferably a p-hydroxyphenylstearyl group.

In the polyamide resin of the present invention, two or more kinds of the above-mentioned hydrocarbon groups having a hydroxyphenyl group may be mixed and bonded to the terminal.

In the polyamide resin of the present invention, the ratio of the hydrocarbon group having an amide-bonded hydroxyphenyl group at the terminal is preferably 20 to 95 mol% of all the terminal groups, and more preferably 25 to 90 mol%. If this ratio is less than 20 mol%, the effect of lowering the water absorption of the polyamide resin is not recognized, and if it exceeds 95 mol%, it is highly effective in reducing the water absorption of the polyamide resin, but the production is Have difficulty.

The term "all terminal groups" as used herein means the sum of the hydrocarbon group having the hydroxyphenyl group, the unreacted amino group and the unreacted carboxyl group. That is, in the polyamide resin of the present invention, a hydrocarbon group having a hydroxyphenyl group as an end group, an amino group and a carboxyl group are mixed.

The polyamide resin of the present invention has a relative viscosity of 1.8 to 5,
It is preferably 2-5. If the relative viscosity deviates from the above range, handling in manufacturing becomes difficult in any case.

The relative viscosity is measured according to JIS K6810.

The polyamide resin of the present invention is produced, for example, as follows, but the production method is not particularly limited to this method.

As a production method, a method of binding a hydrocarbon monocarboxylic acid having a hydroxyphenyl group to a terminal amino group of a polyamide (production method) and a hydrocarbon monocarboxylic acid having a hydroxyphenyl group and a diamine compound are used in combination, A method (manufacturing method) of bonding a hydrocarbon group having a hydroxyphenyl group to both the terminal carboxyl group and the amino group of the polyamide can be mentioned.

In both the production method and the case, a raw material monomer of polyamide is charged into a polymerization tank, and a monocarboxylic acid of a hydrocarbon having a hydroxyphenyl group or a monocarboxylic acid of a hydrocarbon having a hydroxyphenyl group and a diamine compound are added thereto. Then, polymerization is carried out under normal pressure or reduced pressure, or by this combined method.

The hydrocarbon monocarboxylic acid having a hydroxyphenyl group used in the production method is a monocarboxylic acid in which a carboxyl group is bonded to the above-mentioned hydrocarbon group having a hydroxyphenyl group, and is represented by p-hydroxyphenylstearic acid. As an example,
Other examples include p-hydroxypalmitic acid and the like, and the invention is not particularly limited thereto.

Such monocarboxylic acids are, for example, oleic acid, tal
Of monounsaturated fatty acids such as mitooleic acid and phenol
It can be produced by addition reaction (JAOCS,61
(6), 1048-1051, 1984).

These hydrocarbon monocarboxylic acids having a hydroxyphenyl group are used per 1 mol of the polyamide raw material monomer.
It is used in 1/120 to 1/500 mol, preferably 1/150 to 1/400 mol.

As the monocarboxylic acid of the hydrocarbon having a hydroxyphenyl group used in the production method, the monocarboxylic acid used in the above production method can be used, and as the diamine compound, ethylenediamine, tetramethylenediamine, hexamethylene are used. Diamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4- / 2,4,
4-trimethylhexamethylenediamine, 5-methylnonamethylenediamine, m-xylylenediamine, p-xylylenediamine, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1- Amino-3-aminomethyl-3,5,5-trimethylcyclohexane, bis (4-aminocyclohexyl)
Methane, bis (3-methyl-4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl)
Examples thereof include propane, bis (aminopropyl) piperazine, aminoethylpiperazine, polyethylene glycol amine and polypropylene glycol amine.

The above-mentioned hydrocarbon monocarboxylic acid having a hydroxyphenyl group is 1/60 based on 1 mol of the polyamide raw material monomer.
~ 1/300 mol, preferably 1/75 to 1/250 mol, and the diamine compound is 1/120 to 1/500 mol, preferably 1/150 to 1/400 mol, relative to 1 mol of the polyamide raw material monomer. used.

If the blending amount of the monocarboxylic acid or diamine compound of the hydrocarbon having a hydroxyphenyl group used in the production method and / or is too small, the water absorption of the polyamide resin cannot be lowered sufficiently, and conversely if it is too large. The polyamide resin has a low viscosity and is difficult to handle.

Since the polyamide resin of the present invention has a hydrocarbon group having a hydroxyphenyl group at the terminal of the polyamide, the hydroxy group having a strong acidity of the hydroxyphenyl group forms a hydrogen bond with the amide group inside the polyamide, It is considered that the formation of a hydrogen bond between an amide group and a water molecule is hindered, and therefore the water absorption of the polyamide resin can be greatly reduced.

(Examples) Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

In the examples, the quantification of the hydrocarbon group having a hydroxyphenyl group was carried out by hydrolyzing the polyamide with hydrochloric acid, esterifying the hydrolyzate, and then quantifying it by gas chromatography. This can be confirmed by measuring the concentration of the amide group and / or carboxyl group of the polyamide as an index of the amide bond of the hydrocarbon group having a hydroxyphenyl group at the terminal of the polyamide. The amino group concentration was determined by dissolving polyamide in phenol and titrating with 0.05N hydrochloric acid, and the carboxyl group concentration was determined by dissolving the polyamide in benzyl alcohol and titrating with 0.05N caustic soda.

The relative viscosity is measured according to JIS K6810, the melting point,
The freezing point was measured by the DSC method.

Example 1 In a 100 ml autoclave, ε-caprolactam 40 g and water
2 g and p-hydroxystearic acid (Nova Acid P, manufactured by NOF CORPORATION) were charged in an amount shown in Table 1, the system was replaced with nitrogen, and the system was sealed. This was heated to 260 ° C., reacted under pressure with stirring for 3 hours, then released, and further reacted at 260 ° C. for 6 hours in a nitrogen stream. After the obtained polymer was cut, unreacted monomers were extracted and removed using boiling water and dried. The relative viscosity of the obtained polymer is JI
It was measured according to S K6810. 260 ° C of the obtained polymer
A 15 mm × 30 mm × 3 mm plate was prepared by hot pressing at elevated temperature and left at 40 ° C in an atmosphere of 90% RH for 20 days, and the saturated water absorption was calculated from the weight change.

The results are shown in Table 2 together with the physical properties of the polymer.

Examples 2-6 40 g of ε-caprolactam and water 2 in a 100 ml autoclave
g, p-hydroxystearic acid in the amount shown in Table 1 and diamine having the content shown in Table 1 were charged in respective amounts and polymerized under the same conditions as in Example 1, and the produced polymer was the same as in Example 1. It evaluated by the method.

The results are shown in Table 2.

Example 7 30 autoclave with ε-caprolactam 10 kg, water 2 k
g, p-hydroxystearic acid and hexamethylenediamine in the amounts shown in Table 1 were charged, and the system was replaced with nitrogen and then sealed. This was heated to 260 ° C., reacted under pressure for 2 hours with stirring, then released, and further under a nitrogen atmosphere.
The reaction was carried out at 0 ° C. under a reduced pressure of 460 Torr for 6 hours. The obtained polymer was extracted and removed, and then dried. A tensile test piece was molded from the obtained polymer using a 1 ounce injection molding machine at a resin temperature of 250 ° C., a mold temperature of 80 ° C., an injection time of 3 seconds, and a cooling time of 10 seconds. The saturated water absorption was measured under the same conditions as in 1.

Comparative Example 1 Example 1 was repeated except that the amount of acetic acid shown in Table 1 was used instead of -hydroxystearic acid in Example 1.
A polyamide resin was produced in the same manner as in, and the obtained polymer was evaluated in the same manner as in Example 1. The results are also shown in Table 2.

[Effects of the Invention] The polyamide resin of the present invention has a significantly lower water absorption than conventional polyamide resins, so that it is possible to perform well-known molding methods such as injection molding, extrusion molding and compression molding. In addition, it is possible to obtain an industrially extremely useful molded product that has a small dimensional change due to water absorption and has little deterioration in physical properties.

Claims (1)

[Claims] 1. At the end, the following formula: (In the formula, m and n represent integers satisfying 2 ≦ m + n ≦ 22; ^one of R ¹ and R ² is And the other represents a hydrogen atom), a polyamide resin having a hydrocarbon group having a hydroxyphenyl group.