JP3399475B2 - Polyamide resin composition - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyamide resin composition, and more particularly, to the excellent mechanical properties, heat resistance and chemical resistance of a conventional polyamide resin. Polyamide resin composition that simultaneously imparts three effects, that is, improvement of long-term heat aging resistance, suppression of metal copper precipitation in a molding machine at the time of molding, and suppression of color change of resin due to water absorption with time, without impairing the properties. It is about. [0002] Polyamide resins are widely used in the fields of automobiles and electric and electronic fields, taking advantage of their excellent mechanical properties, heat resistance, chemical resistance and flame retardancy. Above all, polyamide resins have excellent long-term heat aging properties that are not seen in other resins, and are therefore used for parts to which extremely high-temperature heat is applied, such as in an engine room of an automobile. In particular, in recent years, with the increase in the density of parts in the engine room of automobiles and the increase in engine output, the environmental temperature in the engine room has been increasing, and polyamide resins have been required to have higher long-term heat aging resistance than ever before. Have been. In response to this, various technical improvements have been attempted so far, for example, a polyamide resin composition containing a copper compound and a halogen compound (JP-B-53-382297).
JP, JP-B-59-52669), polyamide resin compositions containing a triazole compound or an imidazole compound (JP-A-3-76752, JP-A-3-76753), aromatic amines, hindered phenols There are known polyamide resin compositions and the like in which a systemic oxidation deterioration inhibitor is blended. Among them, a technique for improving heat aging resistance by a mixture of a copper compound and a halogen compound is most excellent in cost performance, and is still widely used at present. However, in the polyamide resin composition containing the mixture of the copper compound and the halogen compound, the heat aging resistance is improved by increasing the content of the copper compound and the halogen compound. Is easily precipitated in the molding machine, and is mixed into the molded product as metallic copper, that is, the problem that the insulation of the molded product is impaired occurs. Further, there was a problem that the color of the molded article gradually changed from white to green in the course of gradually absorbing water, and the degree of the color change increased as the copper concentration was increased. Therefore, despite the fact that there is an excellent additive for improving high heat aging resistance, which is a mixture of a copper compound and a halogen compound, there are two problems of copper precipitation in a molding machine and discoloration of a molded product. The amount of the halogen compound in the polyamide was limited, and a polyamide resin composition having sufficiently satisfactory heat aging resistance could not be obtained. [0005] In view of such circumstances, an object of the present invention is to greatly improve the long-term heat aging resistance of a polyamide resin, and further significantly reduce the precipitation of metallic copper in a molding machine. Another object of the present invention is to provide a polyamide resin composition in which a change in appearance color due to water absorption of the obtained molded article is extremely small. The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that a mixture of a copper compound and an iodine compound having a specific blending ratio, and an aliphatic carboxylic acid Or by blending a derivative thereof, and specifying the carboxyl group concentration ratio to the total amount of the carboxyl group concentration and the amino group concentration in the polyamide composition,
We found that we could solve all of the above issues specifically,
The present invention has been completed. In particular, by simply 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, such a problem can be solved at once. Surprisingly,
This is the finding first clarified by the present invention. That is, the present invention relates to (A) a polyamide resin and (B) a polyamide resin having a copper concentration of 1 p.
a copper compound that satisfies not less than pm and not more than 200 ppm;
(C) The ratio of gram atoms of iodine to copper (I / Cu) is 1
An iodine compound satisfying 2 to 40, and (D)
A polyamide resin composition comprising an aliphatic carboxylic acid or a derivative thereof in an amount of 0.01 part by weight or more and 0.5 part by weight or less based on 100 parts by weight of a polyamide resin, and (E) a carboxyl group concentration in the polyamide resin composition. And a polyamide resin composition having a carboxyl group concentration ratio of 50% or more to the total amount of the amino group concentrations. It is the gist. Hereinafter, the contents of the present invention will be described in detail.
The polyamide used in the present invention is not particularly limited as long as it is a known polyamide, and may be any of a homopolyamide, a copolymerized polyamide, and a blended polyamide. Representative examples include ε-caprolactam, enantholactam,
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, isophoronediamine, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and 1,3-cyclohexanedicarboxylic acid Acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid,
There are polyamides obtained from dicarboxylic acids such as dimer acids. As specific examples, 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 @ Ny
66, Ny66 / 6T‖Ny6, Ny66 / 6‖Ny6
And the like. 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. A range of 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, copper isophthalate, and the like.
A copper complex salt or the like coordinated to a chelating agent may be used. These copper compounds may be used alone or in combination of two or more. The addition amount of the copper compound is 1 to 200 ppm in copper concentration,
Preferably it is 15 to 150 ppm. Copper concentration is 1pp
When the value is less than m, the heat-resistant effect becomes insufficient, which is not preferable. Even when the copper concentration is more than 200 ppm, not only the heat-resistant aging property is not significantly improved, but also it is possible to suppress the precipitation of copper and the discoloration of the molded product. It will be difficult. The iodine compound used in the present invention includes sodium iodide, potassium iodide, iodine and the like. The amount of the iodine compound to be added is 12 to 40, preferably 20 to 30, in terms of the gram atomic 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. When the gram atomic ratio of copper and iodine is more than 40, further increase is caused. This is not preferable because not only the improvement effect is not obtained but also a new problem such as corrosion of the screw of the molding machine is caused. The copper compound and the iodine compound may be added at the time of polymerizing the polymer, or may be blended with the polyamide in an extruder. There is no particular limitation on the blending method, and the compound can be blended with the polyamide by a known method. The aliphatic carboxylic acids or derivatives thereof used in the present invention include capric acid, lauric acid, palmitic acid, stearic acid, myristic acid, pehenic acid,
Cerotic acid, montanic acid, melicic acid, oleic acid, elaidic acid, linoleic acid, linolenic acid, erucic acid, and / or the sodium salt of these aliphatic carboxylic acids ;
Calcium salts, aluminum salts, esterified compounds and the like can be mentioned. The aliphatic carboxylic acid or derivative thereof 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 based on 100 parts by weight of the polyamide resin.
Not less than 0.01 part by weight and not more than 0.5 part by weight,
If less than parts by weight, the effect of preventing copper precipitation is small,
If the amount is more than 0.5 part 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%.
A resin composition having the above carboxyl group. The carboxyl group concentration ratio in the present invention refers to the carboxyl group concentration and the amino group concentration in the polyamide resin product, respectively [C
OOH] and [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 precipitated in the molding machine, making it impossible to perform long-term continuous molding, and the discoloration of the molded product due to water absorption becomes remarkable, lowering the commercial value. Carboxyl group concentration ratio is 50%
The above polyamide resin composition may be obtained by adding the above-mentioned aliphatic carboxylic acid compound, but is easily obtained by adding another carboxylic acid at the time of polymer polymerization. Examples of other carboxylic acids include acetic acid, caproic acid, undecanoic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid and the like. These carboxylic acid compounds are added such that the carboxyl group concentration ratio of the polyamide polymer composition becomes 50% or more. The polyamide resin composition of the present invention may contain other additives such as an antistatic agent, a coloring agent, a crystal nucleating agent, a lubricant, a filler, a reinforcing agent, a light-fast agent and the like to such an extent that the effects of the present invention are not significantly impaired. Can be added in an appropriate amount at any stage. Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. In Examples and Comparative Examples, the long-term heat aging resistance, the copper deposition rate, the change in color tone, the carboxyl group concentration, and the amino group concentration of the molded articles were measured by the following methods. (1) Long-term heat aging resistance After the test piece obtained under the following molding conditions was treated in a hot air oven at 180 ° C. for a predetermined time, ASTM-
The tensile strength was measured according to D638. Then, the tensile strength after the heat treatment with respect to the tensile strength measured before the heat treatment was calculated as a tensile strength retention. The heat treatment time at which the tensile strength retention was 50% was defined as the half life. (2) Deposition rate of copper The polyamide resin composition was retained in a molding machine set at a cylinder temperature of 280 ° C. for 60 minutes. After the retention, the polyamide resin composition was molded under the following molding conditions. After the retention, the copper concentration of the second shot was measured. . The method for measuring the copper concentration is as follows. (Method of Measuring Copper Concentration in Molded Article) Zinc Carbamate Colorimetric Method 0.5 g of sample is precisely weighed. 2. 10 ml of 7N hydrochloric acid is added to dissolve the sample. 3. 20 ml of a 0.02% xylene solution of zinc N-ethyl-N-phenyldithiocarbamate are added. 4. Shake for 10 minutes to separate the solution. 5. Only the xylene solution layer was taken out, and measured with a colorimeter (UVIDEC610-C manufactured by JASCO Corporation) at 460 μm.
The absorbance at is measured. (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 article obtained without stagnation and the copper concentration was defined as the amount of copper deposition, and the value expressed as a ratio (%) to the amount of copper at the time of addition was defined as the copper deposition rate. (3) Color tone change The test piece obtained under the following molding conditions was 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, 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 after water absorption process L, a, b values a _B, b _B, L _B water pretreatment L, a, b values 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 The test piece obtained under the following molding conditions was pulverized, dissolved in benzyl alcohol, and the carboxyl group concentration was measured. 1. Add 50 ml of benzyl alcohol. 2. Heat to 170 ° C. with mantle heater. 3. Add phenolphthalein. 4. 4.0 g of sample is precisely weighed and added. 5. After dissolving, titrate with 0.1N NaOH aqueous solution. 6. Carboxyl group concentration = (f × 0.1 × A / S) ×
100 f: Factor of 0.1 N NaOH aqueous solution A: Consumption of 0.1 N NaOH aqueous solution [ml] S: Sample weight [g] (5) Amino group Test piece obtained under the following molding conditions Was crushed and dissolved in an aqueous phenol solution, and the amino group concentration was measured. 1. 3 g of a sample is dissolved in 100 ml of a 90% aqueous phenol solution. 2. 1 / 40N hydrochloric acid is added dropwise to neutralize. 3. Determine the amount of hydrochloric acid required up to the neutralization point. 4. Perform the same measurement without adding a sample, and use it as a blank. 5. Amino group concentration = ΔF × (1/40) × (AB)
/ S｝ × 1000 F: Factor of 1 / 40N hydrochloric acid A: Consumption of 1 / 40N hydrochloric acid [ml] B: Consumption of 1 / 40N hydrochloric acid (blank) [ml] S: Sample weight [g] (Molding conditions) Injection molding machine: Nissei Resin PS-40E Mold: ASTM-D638 Test piece cylinder temperature: 280 ° C Flat mold temperature: 80 ° C Plasticization stroke: 63 mm Screw rotation speed: 200 rpm Injection time: 10 Cooling time per second: 15 seconds Polyamide resin compositions of Examples and Comparative Examples were obtained as follows. An equimolar salt solution of hexamethylenediamine and adipic acid ( 100 wt%)
0.0174 parts by weight of copper iodide,
0.2893 parts by weight of lithium and 0.38 layers of adipic acid
The polymer shown in Table 1 was obtained by a known melt polymerization method . The obtained polymer has a Cu (copper) concentration of 6
7ppm, I (iodine) concentration 2680ppm (all
Analytical value / by ICP emission method) and I / C
When expressed in u-gram atomic ratio, (2680 / 126.90) /
(67 / 63.55) = 20. The amount of the aliphatic carboxylic acid compound shown in Table 2 was blended with 100 parts by weight of the obtained polymer using a Henschel mixer. The long-term heat aging resistance, copper deposition rate, and change in color tone of each polymer were measured, and the physical properties shown in Table 2 were obtained. [Table 1] [Table 2] According to the present invention, the precipitation of metallic copper in a molding machine, which has a well-known conventional technique of improving the heat aging resistance by blending a copper compound and an iodine compound with a polyamide resin, With respect to the change over time of the color tone of the molded article due to water absorption, the amount of the known copper compound and iodine compound is optimized, an aliphatic carboxylic acid compound is added, and the carboxyl group concentration ratio of the polyamide resin composition is 50% or more. By doing so, without impairing the excellent mechanical properties, heat resistance, and chemical resistance of the polyamide resin composition obtained by blending the copper compound and the iodine compound, further, improvement of long-term heat aging resistance, molding A polyamide resin capable of simultaneously satisfying the three effects of suppressing the precipitation of metallic copper in the machine and suppressing the change in color tone of the molded article with time due to water absorption. The composition could be provided.

Continuation of the front page (56) References JP-A-62-263319 (JP, A) JP-A-3-76755 (JP, A) JP-B 38-1128 (JP, B1) JP-B 36-4009 (JP) , B1) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 77/00 C08K 3/16 C08K 5/09

Claims (1)

(57) [Claims 1] The copper concentration is 1 ppm or more to (A) polyamide resin and (B) polyamide resin.
Copper iodide, copper acetate, propylene
Copper onate, copper benzoate, copper adipate, terephthalic acid
From copper, copper isophthalate, copper complex salt coordinated to chelating agent
At least one copper compound selected and, relative to (C) Iodine compound ratio of gram atoms of iodine and copper (I / Cu) satisfies 12 to 40. and, (D) a polyamide resin 100 parts by weight , 0.01
Not less than 0.5 part by weight of an aliphatic carboxylic acid ,
Thorium salt, calcium salt, aluminum salt, ester
And (E) a polyamide resin composition having a carboxyl group concentration ratio of 50% or more to the total amount of the carboxyl group concentration and the amino group concentration in the polyamide resin composition. object.