JPH0718176A - Polyamide resin composition - Google Patents

Abstract

PURPOSE:To obtain a resin composition, capable of remarkably improving the heat aging resistance for a long period and further reducing deposition of metallic copper in a molding machine and providing moldings with hardly any change in the appearance and color by absorbing water. CONSTITUTION:This polyamide resin composition is composed of a polyamide resin, a copper compound, an iodine compound and a compound of a carboxylic acid and capable of satisfying the following: (1 1<= copper concentration <=200ppm; (2) 12<=g atomic ratio (I/Cu) of iodine to copper <=40; (3) the carboxylic acid is an aliphatic carboxylic acid or its derivative in an amount of >=0.01 t <=0.5 pt.wt. based on 100 pts.wt. polyamide resin and (4) >=50% carboxyl group concentration ratio of the carboxyl group concentration to the total amount of the carboxyl group and amino group concentrations in the polyamide resin composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide resin composition, and more specifically, it does not impair the excellent mechanical properties, heat resistance, and chemical resistance of conventional polyamide resins, and further provides long-term heat resistance. The present invention relates to a polyamide resin composition that simultaneously provides three effects, namely, improvement of aging property, suppression of metallic copper deposition in a molding machine during molding, and suppression of temporal change of resin color tone due to water absorption.

[0002]

2. Description of the Related Art Polyamide resins are widely used in the fields of automobiles and electric / electronic fields by taking advantage of their excellent mechanical properties, heat resistance, chemical resistance and flame retardancy. Among them, the polyamide resin is excellent in long-term heat aging resistance that is not found in other resins, and is therefore used in parts of parts such as an automobile engine room to which heat of extremely high temperature is applied. In recent years, in particular, with the increasing density of automobile engine room parts and the increase in engine output, the environmental temperature inside the engine room has become higher and higher, and polyamide resins are required to have higher long-term heat aging resistance than ever before. Came.

In response to this, various technical improvements have been tried so far, for example, a polyamide resin composition containing a copper compound and a halogen compound (Japanese Patent Publication No. 53-38297).
JP, JP-B-59-52669), a polyamide resin composition containing a triazole compound or an imidazole compound (JP-A-3-76752, JP-A-3-76753), an aromatic amine, a hindered phenol. Polyamide resin compositions and the like containing a system oxidative deterioration inhibitor are known. Among these, the heat aging resistance improving technique using a mixture of a copper compound and a halogen compound is the most excellent in terms of cost performance, and is still widely used today.

However, even in the polyamide resin composition containing the mixture of the copper compound and the halogen compound, if the content of the copper compound and the halogen compound is increased, the heat aging resistance is improved accordingly. Will tend to deposit in the molding machine and will be mixed into the molded product as metallic copper, that is, the insulating property of the molded product will be impaired. Further, there has been a problem that the molded product changes its color from white to green in the process of gradually absorbing water, and the degree of discoloration increases as the copper concentration increases. Therefore, even though there was an excellent additive for improving the high heat resistance aging property, which was a mixture of a copper compound and a halogen compound, there were two problems of copper precipitation in the molding machine and discoloration of the molded product. The amount of the halogen compound compounded in the polyamide is limited, and a polyamide resin composition having a sufficiently satisfactory heat aging resistance cannot be obtained.

[0005]

In view of such circumstances, an object of the present invention is to significantly improve the long-term heat aging resistance of a polyamide resin, and further significantly reduce the deposition of metallic copper in a molding machine. An object of the present invention is to provide a polyamide resin composition in which the appearance color change of a molded article due to water absorption is extremely small.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a mixture of a copper compound and an iodine compound having a specific mixing ratio, and an aliphatic carboxylic acid or a derivative thereof. By blending, by specifying the carboxyl group concentration ratio to the total amount of the carboxyl group concentration and amino group concentration in the polyamide composition,
We found that we could specifically solve all of the above issues,
The present invention has been completed. In particular, by optimizing the compounding ratio of the copper compound and the iodine compound, adding an aliphatic carboxylic acid or a derivative thereof, and controlling the carboxyl group concentration ratio in the polyamide resin composition, it is possible to solve all of these problems at once. It ’s amazing,
This is the finding first clarified by the present invention.

That is, the present invention has a copper concentration of 1 p with respect to (A) polyamide resin and (B) polyamide resin.
a copper compound satisfying pm or more and 200 ppm or less, and
(C) The ratio of gram atom of iodine to copper (I / Cu) is 1
An iodine compound satisfying 2 or more and 40 or less, and (D)
A polyamide resin composition comprising 0.01 part by weight or more and 0.5 part by weight or less of an aliphatic carboxylic acid or a derivative thereof with respect to 100 parts by weight of a polyamide resin, wherein (E) the carboxyl group concentration in the polyamide resin composition. A polyamide resin composition having a carboxyl group concentration ratio of 50% or more with respect to the total amount of amino acid and amino groups. Is the gist.

The contents of the present invention will be described in detail below.
The polyamide used in the present invention is not particularly limited as long as it is a known polyamide, and may be any of homopolyamide, copolymerized polyamide and blended polyamide. As a typical example, ε-caprolactam, enanthlactam,
Lactams such as ω-laurolactam, ε-aminocaproic acid, 11-aminoundecanoic acid, aminocarboxylic acids such as 12-aminododecanoic acid, tetramethylenediamine,
Hexamethylenediamine, undecamethylenediamine,
Dodecamethylenediamine, 2,2,4- / 2,4,4-
Trimethylhexamethylenediamine, 5-methylnonamethylenediamine, m-xylylenediamine, p-xylylenediamine, 1,3-bisaminomethylcyclohexane, 1,4-bisaminomethylcyclohexane, bis-
Diamines such as p-aminocyclohexylmethane, bis-p-aminocyclohexylpropane and isophoronediamine, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid Acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid,
There are polyamides obtained from dicarboxylic acids such as dimer acid.

As a specific example, Ny6, Ny11, Ny1
2, Ny66, Ny46, Ny610, Ny612, N
Homopolymers such as y6I, Ny66 / 6 (/ indicates a copolymer), Ny66 / 610, Ny66 /
612, Ny66 / 6I, Ny66 / 6T, Ny66 /
6T / 6I, Ny66 / 6T / 612, Ny6T / 6
I, Ny6T / 6I / 612, Ny6T / 6 and other copolymers, Ny66 / | Ny6 (‖ indicates a blend), Ny66 / 6I / Ny6, Ny66 / 6T / Ny6
66, Ny66 / 6T | Ny6, Ny66 / 6 | Ny6
There are blend polymers such as.

The polyamide used in the present invention is obtained by a known polymerization technique, and may be any of melt polymerization, solid phase polymerization, solution polymerization, interfacial polymerization and the like, and the molecular weight of the polymer is not limited and the known molecular weight is known. Ranges can be used. Examples of the copper compound used in the present invention include copper iodide, copper acetate, copper propionate, copper benzoate, copper adipate, copper terephthalate, and copper isophthalate.
A copper complex salt coordinated with a chelating agent may be used. These copper compounds may be used alone or in combination of two or more. The amount of copper compound added is 1 to 200 ppm in terms of copper concentration,
It is preferably 15 to 150 ppm. Copper concentration is 1pp
If it is less than m, the heat resistance effect becomes insufficient, which is not preferable, and even if the copper concentration exceeds 200 ppm, not only the heat aging resistance is not significantly improved, but also copper precipitation and discoloration of the molded product can be suppressed. It will be difficult.

Examples of the iodine compound used in the present invention include sodium iodide, potassium iodide, iodine and the like. The addition amount of the iodine compound is 12 to 40, preferably 20 to 30 in terms of gram atom ratio (I / Cu) of copper and iodine in the resin composition. When the gram atomic ratio of copper and iodine is less than 12, it is difficult to suppress the precipitation of copper and the discoloration of the molded product, which is not preferable, and when the gram atomic ratio of copper and iodine is more than 40, further Not only the improvement effect is not obtained, but also a new problem of corroding the screw of the molding machine is caused, which is not preferable. The copper compound and iodine compound may be added at the time of polymerizing the polymer, or may be blended with the polyamide in the extruder, and there is no particular limitation on the blending method, and the compound can be blended with the polyamide by a known method.

Examples of the aliphatic carboxylic acid or its derivative used in the present invention include capric acid, lauric acid, palmitic acid, stearic acid, myristic acid, pehenic acid,
Examples thereof include cerotic acid, montanic acid, melissic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, erucic acid, and / or metal salts and esterified products of these aliphatic carboxylic acids. The aliphatic carboxylic acid or its derivative of the present invention can be added to the polyamide resin by a known method such as melt-kneading using an extruder or adding a blend to the pellet surface. The addition amount of these aliphatic carboxylic acid compounds is 0.01 parts by weight or more and 0.5 parts by weight or less with respect to 100 parts by weight of the polyamide resin, and if less than 0.01 parts by weight, it is effective in preventing the precipitation of copper. When the amount is less than 0.5 parts by weight, no further effect can be expected in preventing the precipitation of copper.

The polyamide resin composition of the present invention has a carboxyl group concentration ratio of 50% or more, preferably 63%.
It is a resin composition having the above carboxyl groups. The term “carboxyl group concentration ratio” as used in the present invention means the carboxyl group concentration and the amino group concentration in the polyamide resin product, respectively [C
OOH], [NH ₂ ] as {[COOH] / ([CO
OH] + [NH ₂ ])} × 100. If the carboxyl group concentration ratio is less than 50%, a large amount of metallic copper is deposited in the molding machine, continuous molding cannot be performed for a long period of time, and discoloration of the molded product due to water absorption becomes remarkable and the commercial value is lowered. Carboxyl group concentration ratio is 50%
Although the above polyamide resin composition may be obtained by adding the above-mentioned aliphatic carboxylic acid compound, it can be easily obtained by adding another carboxylic acid during polymer polymerization.

Examples of other carboxylic acids are acetic acid, caproic acid, undecanoic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, terephthalic acid and isophthalic acid. The amount of these carboxylic acid compounds added is such that the carboxyl group concentration ratio of the polyamide polymer composition is 50% or more. In the polyamide resin composition of the present invention, other additives such as antistatic agents, colorants, crystal nucleating agents, lubricants, fillers, reinforcing agents, light stabilizers, etc. are added to the extent that the effects of the present invention are not significantly impaired. Can be added in an appropriate amount at any stage.

[0015]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. In Examples and Comparative Examples, long-term heat aging resistance, copper deposition rate, color tone change, carboxyl group concentration, and amino group concentration of molded products were measured by the following methods. (1) Long-term heat aging resistance A test piece obtained under the following molding conditions was treated in a hot air oven at 180 ° C. for a predetermined time, and then ASTM-
The tensile strength was measured according to D638. Then, the tensile strength after heat treatment with respect to the tensile strength measured before heat treatment was calculated as the tensile strength retention rate. The half-life was defined as the heat treatment time at which the tensile strength retention rate was 50%. (2) Copper Deposition Rate The polyamide resin composition was retained in a molding machine set at a cylinder temperature of 280 ° C. for 60 minutes, molded after the retention under the following molding conditions, and the copper concentration of the second molded article after retention was measured. . The measuring method of the copper concentration is as follows.

(Measuring Method of Copper Concentration in Molded Article) Zinc Carbamate Colorimetric Method 1. A 0.5 g sample is precisely weighed. 2. Add 10 ml of 7N hydrochloric acid to dissolve the sample. 3. 20 ml of a 0.02% solution of zinc N-ethyl-N-phenyldithiocarbamate in xylene is added. 4. Shake for 10 minutes to allow the solution to separate. 5. Only the xylene solution layer was taken out and 460 μm by a colorimeter (UVIDEC610-C manufactured by JASCO Corporation).
Measure the absorbance at. (ABS _S ) 6. Measure the absorbance of the blank with no sample added. (ABS _B ) 7. Calculation: Copper concentration = 104.2 × (ABS _S −ABS
_B ) / Sample weight The difference between the copper concentration of the molded product obtained without retention and the copper deposition amount was defined as the copper deposition amount, and the value represented by the ratio (%) to the amount of copper at the time of addition was defined as the copper deposition rate. (3) Change in color tone The test piece obtained under the following molding conditions is at 23 ° C.
Was immersed in water for 240 hours, and the color tone of the test piece after immersion was measured with a color difference meter (ND-K6B type manufactured by Nippon Denshoku Co., Ltd.). The measurement conditions are as follows.

[0017] Measurement items: L (lightness), a (redness), b (yellowness) Delta] E (color difference) _{calculations: ΔE = √ {(L S} -L B) 2 + (a s -
a _B ) ² + (b _S −b _B ) ² } a _S , b _S , L _S L, a, b values after water absorption treatment a _B , b _B , L _B L, a, b values before water absorption treatment The color difference (ΔE) from the color tone of the molded product before water absorption was defined as the color tone change. (4) Carboxyl group A test piece obtained under the following molding conditions was crushed and dissolved in benzyl alcohol to measure the carboxyl group concentration. 1. Add 50 ml of benzyl alcohol. 2. Heat to 170 ° C with a mantle heater. 3. Add phenolphthalein. 4. A sample of 4.0 g is precisely weighed and added. 5. After dissolution, titration is performed with 0.1N NaOH aqueous solution. 6. Carboxyl group concentration = (f × 0.1 × A / S) ×
100 f: Factor of 0.1N NaOH aqueous solution A: Consumption of 0.1N NaOH aqueous solution [ml] S: Sample weight [g]

(5) Amino group A test piece obtained under the following molding conditions was crushed and dissolved in an aqueous phenol solution to measure the amino group concentration. 1. 3 g of a sample is dissolved in 100 ml of 90% phenol aqueous solution. 2. 1/40 N hydrochloric acid is added dropwise to neutralize. 3. Calculate the amount of hydrochloric acid required up to the neutralization point. 4. Perform the same measurement without adding the sample and use it as a blank. 5. Amino group concentration = {F × (1/40) × (AB)
/ S} × 1000 F: 1 / 40N hydrochloric acid factor A: 1 / 40N hydrochloric acid consumption [ml] B: 1 / 40N hydrochloric acid consumption (blank) [ml] S: sample weight [g]

(Molding conditions) Injection molding machine: PS-40E mold made by NISSEI RESIN: ASTM-D638 test piece mold Cylinder temperature: 280 ° C. Flat mold temperature: 80 ° C. Plasticizing stroke: 63 mm Screw rotation speed: 200 rpm Injection time : 10 seconds Cooling time: 15 seconds The polyamide resin compositions of Examples and Comparative Examples were obtained as follows.

A known melt polymerization method in an autoclave using an aqueous solution of an equimolar salt of hexamethylenediamine and adipic acid (50 wt% concentration), a copper compound, an iodine compound, and an aqueous solution of adipic acid or hexamethylenediamine as a starting material. Thus, the polymers shown in Table 1 were obtained. The amount of the aliphatic carboxylic acid compound shown in Table 2 added to 100 parts by weight of the obtained polymer was blended with a Henschel mixer. The long-term heat aging resistance, copper deposition rate, and color change of each polymer were measured to obtain the physical properties shown in Table 2.

[0021]

[Table 1]

[0022]

[Table 2]

[0023]

EFFECTS OF THE INVENTION According to the present invention, a polyamide resin is blended with a copper compound and an iodine compound to improve the heat-resistant aging resistance. Regarding the change with time of the color tone of the product, the compounding amounts of the known copper compound and iodine compound are optimized, the aliphatic carboxylic acid compound is added, and the carboxyl group concentration ratio of the polyamide resin composition is 50% or more. By doing so, excellent mechanical properties of the polyamide resin composition containing a copper compound and an iodine compound, heat resistance, without impairing the chemical resistance, further improvement in long-term heat aging resistance, metal in the molding machine Provided is a polyamide resin composition capable of simultaneously satisfying the three effects of suppressing the precipitation of copper and suppressing the time-dependent change in the color tone of a molded product due to water absorption. Rukoto was able.

Claims (1)

[Claims] 1. A copper concentration of 1 ppm or more and 200 pp relative to (A) polyamide resin and (B) polyamide resin.
a copper compound satisfying m or less, (C) an iodine compound satisfying a ratio (I / Cu) of gram atoms of iodine and copper of 12 or more and 40 or less, and (D) polyamide resin 1
A polyamide resin composition comprising 0.01 parts by weight or more and 0.5 parts by weight or less of an aliphatic carboxylic acid or a derivative thereof with respect to 00 parts by weight, and (E) a carboxyl group concentration in the polyamide resin composition. A polyamide resin composition having a carboxyl group concentration ratio of 50% or more with respect to the total amount of amino groups.