JP3032252B2 - Polyamide resin composition - Google Patents

Description

[Detailed Description of the Invention] [Industrial application field] The present invention relates to a polyamide resin composition having remarkably improved resistance to heat deterioration and little decrease in physical properties due to moisture absorption. The molded article comprising the polyamide resin composition of the present invention is used particularly for parts in an engine room of an automobile exposed to a high-temperature atmosphere, for example, a connector, a relay block, a binding band, an industrial fastener, a canister, a coil bobbin, and the like.

[Prior art] Polyamide resins represented by nylon 6 and nylon 66 are generally used as molding materials for parts used in high-temperature atmospheres in the field of automobiles and the fields of electric and electronics. It has been used frequently because of its well-balanced physical properties, especially toughness and high heat resistance. However, nylon 66 has a large moisture absorption,
Under high humidity conditions, dimensional changes due to moisture absorption are large,
Further, there is a practical problem that the rigidity is reduced. To solve this problem, the present inventors have disclosed in JP-A-2-28253 a polyamide resin molding material having good moldability comprising a specific crystalline aromatic ring-containing polyamide and a small amount of an aliphatic polyester, and having a small decrease in physical properties due to moisture absorption. Suggested. However, in a use environment in which the composition is exposed to a high temperature atmosphere for a long time, such as an engine room of an automobile, heat resistance is required to be deteriorated, whereas the composition obtained by the above invention is not necessarily satisfied. It was not something.

[Problems to be Solved by the Invention] An object of the present invention is to provide a polyamide resin composition which is excellent in moisture resistance and improved in heat deterioration resistance in view of the above situation.

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the polyamide resin molding material proposed above in order to further improve the heat deterioration resistance. As a result, a specific amount of a copper compound and a specific amount of an alkali halide The present inventors have found that by adding a metal salt, it is possible to obtain a polyamide resin composition having excellent heat deterioration resistance and little decrease in physical properties due to moisture absorption, and have led to the present invention.

That is, the present invention provides a crystalline aromatic ring-containing polyamide 70
-100% by weight of a polyamide resin consisting of -98% by weight and 2-30% by weight of an aliphatic polyamide, 0-10% of an aliphatic polyester
Parts by weight, 0.001 to 0.3 parts by weight of a copper compound and a polyamide resin composition comprising 0.005 to 2.0 parts by weight of an alkali metal halide, wherein the copper compound and the alkali metal halide are previously blended with the aliphatic polyamide, The present invention relates to a polyamide resin composition which is melt-mixed with a crystalline aromatic ring-containing polyamide thereafter.

 Hereinafter, the present invention will be described in detail.

In the present invention, whether or not the aromatic ring-containing polyamide is crystalline is determined based on the heat of fusion calculated from the area of the melting peak measured using a differential thermal analyzer.
That is, the case where the heat of fusion is 2.0 cal / g or more is called crystalline. If the heat of fusion is less than 2 cal / g, it becomes a so-called amorphous polymer, the degree of mold adhesion during molding becomes strong, and not only is moldability extremely poor, but also problems arise in terms of chemical resistance.

The crystalline aromatic ring-containing polyamide of the present invention is obtained from a polyamide-forming monomer in which a diamine and / or dicarboxylic acid and / or aminoarbonic acid containing an aromatic ring is present in an amount of 0.1 to 0.6 mol based on 1 mol of all polyamide molding monomers. Obtained by polymerization. When the amount of the monomer containing an aromatic ring is less than 0.1 mol, the resulting polyamide has little effect of reducing the decrease in physical properties during moisture absorption. On the other hand, if it is more than 0.6 mol, the viscosity at the time of melting becomes extremely high, and good moldability cannot be obtained. Further, the polyamide has a melting point of 250 to 300 ° C. measured using a differential thermal analyzer. If the melting point is lower than 250 ° C., the heat resistance is not sufficient, and if the melting point is higher than 300 ° C., a mold deposit or the like occurs at the time of molding, and molding workability is impaired.
A particularly preferred melting point range is 260-290 ° C.

As an example of a monomer forming the crystalline aromatic ring-containing polyamide used in the present invention, a diamine containing an aromatic ring,
Dicarboxylic acids and aminocarboxylic acid compounds include metaxylylenediamine, paraxylylenediamine, terephthalic acid, isophthalic acid, 2-methylterephthalic acid, 2,5
-Dimethyl terephthalic acid, paraaminobenzoic acid, paraaminomethylbenzoic acid, paraaminoethylbenzoic acid and the like. Examples of the polyamide-forming monomer not containing an aromatic ring include diamines such as diaminobutane, hexamethylenediamine, 2-methyldiaminobutane, 2-methylpentamethylenediamine, 2,5-dimethylhexamethylenediamine, succinic acid, and adipine. Acid, sebacic acid,
Dicarboxylic acids such as dotecanedioic acid, ε-caprolactam, lactams such as ω-laurolactam, and aminocarboxylic acids such as 11-aminoundecanoic acid, and the like. These polyamide-forming monomers are mixed and used so as to satisfy the conditions. The polymerization method of the polyamide is melt polymerization, interfacial polymerization,
Melt polymerization, bulk polymerization, solid state polymerization and a combination thereof are used, and generally, melt polymerization is most suitable.
The polyamide used herein may have a molecular weight in a range that can be molded.
Dissolved in 0 ml and measured at 25 ° C) If ηr is 1.6 or more, preferable physical properties are shown.

Specific examples of the polyamide containing a crystalline aromatic ring used in the present invention include nylon 66 / 6T (6T: hexamethylene terephthalamide) copolymer, nylon 6 / 6T copolymer, nylon 6T / 6I (6I: hexamethylene isophthalamide) Copolymer, nylon 610 / 6T copolymer, nylon
612 / 6T copolymer, nylon 66 / 6T / 610 terpolymer,
Nylon 66 / 6T / 612 terpolymer, nylon 66 / 6T / 6 terpolymer and the like.

As the aliphatic polyamide used in the present invention, nylon 66, nylon 6, nylon 69, nylon 610, nylon 612, nylon 46, nylon 11, nylon 12, and the like can be used. There is no particular limitation on the molecular weight of the aliphatic polyamide, but in order to exhibit the compounding effect with a small amount,
It is preferable that the relative viscosity ηr (95% H ₂ SO ₄ ) is 2.3 or more.

The aliphatic polyamide is blended so that the polyamide resin composition of the present invention maintains good physical properties. The addition amount of this aliphatic polyamide is 2 to 30% by weight. If the amount is less than 2% by weight, the effect of improving the tensile elongation is not sufficient, and if the amount is more than 30% by weight, the decrease in physical properties due to moisture absorption is unfavorable.

Although the aliphatic polyester used in the present invention is not necessarily an essential component, it can be molded in a small amount (0.05 to 10 parts by weight based on 100 parts by weight of a polyamide resin comprising a crystalline aromatic ring-containing polyamide and an aliphatic polyamide). In particular, the releasability of the molded product from the mold can be remarkably improved. However, if the amount exceeds 10 parts by weight with respect to 100 parts by weight of the polyamide resin, not only is there no quantitative mixing effect, but also the rigidity of the obtained molded article is lowered, which is not preferable.
The preferred amount is 0.5 to 10 parts by weight, and more preferably the amount is 0.5 to 3 parts by weight.

Aliphatic polyester used in the present invention, succinic acid, phthalic acid, adipic acid, pimelic acid, suberic acid, azelaic acid, aliphatic dibasic acids such as dodecane diacid, ethylene glycol, 1,2-propylene glycol, 1 Condensates with aliphatic diols such as 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, or β-propio It is a ring-opening polymer of a lactone such as lactone, γ-butyrolactone, γ-valerolactone, ε-caprolactone, γ-caprolactone and the like. Preferred examples of the aliphatic polyester include polybutylene adipate, polypropylene sebacate, polybutylene sebacate, and polycaprolactone.
These aliphatic polyesters may be used alone or in combination of two or more. The molecular weight of these polyesters is required to be at least 2,000 or more, preferably 4,000 or more, due to gas generation during molding and volatility from molded products.

The copper compound used in the present invention is an organic / inorganic copper salt or a copper chelate compound which can be uniformly blended with polyamide, such as cuprous chloride, cupric chloride, cuprous iodide, and sulfuric acid. Cupric, cupric nitrate, salicylic acid second
Copper, cupric stearate, cupric acetate, benzoic acid second
Copper and copper sebacate are exemplified. Of these, cuprous iodide and cupric acetate are preferred.

Examples of the alkali metal halide used in the present invention include potassium iodide, potassium bromide, potassium chloride, sodium iodide, sodium bromide, and sodium chloride.

Of these, potassium iodide is preferred. The amount of these heat stabilizers is 0.001 to 0.3 parts by weight, preferably 0.01 to 0.0 parts by weight, based on 100 parts by weight of a polyamide resin comprising a crystalline aromatic ring-containing polyamide and an aliphatic polyamide.
08 parts by weight, and the alkali metal halide salt is 0.005 to 2.0 parts by weight, preferably 0.05 to 0.8 parts by weight.

The effect of improving the heat deterioration resistance by these heat stabilizers can be improved by the copper compound alone, but can be further improved by the combination of the copper compound and the alkali metal halide compound. Any heat stabilizer has an insufficient effect at an amount below the lower limit of the amount used, and the polyamide resin composition is significantly discolored at an amount exceeding the upper limit, or the mechanical properties are significantly reduced, depending on the case. Degrades polyamide. In the combination of a copper compound and an alkali metal halide compound, it is preferable to use the latter in an amount of 5 to 15 times (weight ratio) the former, since the effect becomes remarkable.

Examples of the heat stabilizer used for the polyamide include a copper-based heat stabilizer and a hindered phenol-based and phosphorus-based heat stabilizer as an organic heat stabilizer. However, even if a hindered phenol-based or phosphorus-based heat stabilizer is added to the polyamide resin of the present application, the effect of improving heat deterioration resistance in a high temperature range required for a material used in an engine room of an automobile is not obtained. Not enough. Furthermore, when it is attempted to enhance the effect of improving heat resistance deterioration in a high temperature range by adding a large amount of these heat stabilizers,
There is a large practical problem as a resin molding material that the mold deposit during molding increases.

By compounding a specific amount of a copper compound and a specific amount of an alkali metal halide, a polyamide resin composition having less mold deposit, having excellent heat deterioration resistance under a high temperature atmosphere, and having less deterioration in physical properties due to moisture absorption. Obtainable.

The method for producing the polyamide resin composition of the method of the present invention is described below, but it can be carried out by the usual method for producing a polyamide resin composition. For example, a method of pre-mixing a crystalline aromatic ring-containing polyamide, an aliphatic polyamide, an aliphatic polyester, a copper compound and an alkali metal halide, supplying the mixture to an extruder, melt-kneading the mixture, and then cooling and pelletizing the mixture.
A method in which a copper compound and / or an alkali metal halide is added and compounded at the time of polymerization of a crystalline aromatic ring-containing polyamide and / or an aliphatic polyamide, and the remaining components are melt-kneaded using an extruder or the like. . However,
(1) When a copper compound is added and compounded during the polymerization of the crystalline aromatic-containing polyamide, the foaming of the polymer when the polymer is discharged from the polymerization vessel becomes severe, and it becomes difficult to discharge the polymer from the polymerization vessel. Melting and kneading the aromatic aromatic ring-containing polyamide, aliphatic polyamide, aliphatic polyester, copper compound and alkali metal salt all at once with an extruder reduces the tensile elongation of the finally obtained molded product. In view of this, a method is preferred in which a copper compound and a halogenated alkali metal salt are mixed in advance with an aliphatic polyamide, and then melt-mixed with a crystalline aromatic polyamide. The specific method will be described below. As a method of preliminarily blending the copper compound and the alkali metal halide with the aliphatic polyamide, a method of adding and blending at the time of polymerization of the aliphatic polyamide, that is, the method of adding the copper compound and the alkali metal halide to the aliphatic polyamide forming monomer A method of adding a salt to initiate polymerization in the presence of water, or a method of adding and compounding the copper compound and the alkali metal halide salt during polymerization, or a method of adding and compounding after polymerization of the aliphatic polyamide, And a method in which the copper compound and the alkali metal halide are blended with the aliphatic polyamide by melt mixing using an extruder. As a method of melt-mixing the aliphatic polyamide containing the thus obtained copper compound and the alkali metal halide and the crystalline aromatic ring-containing polyamide,
A method in which an aliphatic polyamide containing a copper compound and an alkali metal halide is melt-mixed using an extruder, or an aliphatic polyamide containing a pre-mixed copper compound and an alkali metal halide is used. A method in which a polyamide pellet and a crystalline aromatic ring-containing polyamide pellet are melt-mixed with an injection molding machine to obtain a desired molded product, and the like.

As a compounding method when compounding the aliphatic polyester, when the copper compound and the alkali metal halide are melted and mixed in advance with the aliphatic polyamide, or when the aliphatic polyamide mixed with the copper compound and the alkali metal halide is crystallized, A method of melt-mixing the aromatic ring-containing polyamide simultaneously with the melt-mixing may be used.

In the polyamide resin composition of the present invention and the method for producing the same, as long as the object of the present invention is not impaired, a heat stabilizer, an antioxidant, a lubricant, a plasticizer commonly used for polyamides,
Flame retardants, antistatic agents, colorants, other resin polymers, and the like can be added at the appropriate manufacturing stage of the present invention.

[Examples] Hereinafter, the present invention will be described in more detail with reference to Examples. In addition, the measurement of each item in each Example and Comparative Example was performed under the following method and conditions.

Melting point and heat of fusion Using a differential scanning calorimeter (DSC-1B, Perkin Elmer), the sound was silenced at a rate of 16 ° C./min in a nitrogen atmosphere, and the peak of the endothermic peak was taken as the melting point. The heat of fusion was determined from the area of the endothermic peak.

ηr (relative viscosity of sulfuric acid) 1 g of polymer was dissolved in 100 ml of 95% sulfuric acid, and the relative viscosity was determined at a constant temperature of 25 ° C.

Humidity control of test piece The test piece immediately after molding was stored in a desiccator at 23 ° C. for 24 hours, and was designated as [DRY].

In contrast, the DRY test piece was placed in hot water at 80 ° C for 8 hours.
After that, immersed in water at 23 ° C for 16 hours, taken out, 23
After leaving for 48 hours in a constant temperature room at 50 ° C and 50% relative humidity, [WE
T].

 Tensile elongation and tensile strength Measured according to ASTM-D638.

 Flexural modulus Measured according to ASTM-D790.

Continuous connector moldability The connector molded product shown in the schematic diagram in Fig. 1 is continuous 100
The continuous formability was evaluated by finding the minimum cooling time for forming a shot stably. The shorter the cooling time, the better the moldability. FIG. 1A is a side view, and FIG. 1B is a plan view seen from the right side of FIG.

Heat Deterioration Resistance According to the method specified in ASTM-D638, a tensile test was performed on a test piece left in a hot-air oven at 150 ° C., and the relationship between the storage time and the tensile strength retention was evaluated.

[Preparation of Crystalline Aromatic Ring-Containing Polyamide] Reference Example 1 Terephthalic acid 17.04 kg, hexamethylene diamine 11.91
kg and 40.32 kg of polyamide 66 salt (AH salt) were supplied to a preheated reaction vessel, and salt formation and concentration were performed at 120 ° C. for 5 hours. The obtained concentrate was kept at 200 ° C. 400
It was supplied to an autoclave and heated to 310 ° C. under pressure. After reacting at 310 ° C. and 18 kg / cm ² for 2 hours, the pressure was lowered, discharged from the autoclave, solidified by cooling, and pelletized. The obtained copolyamide of hexamethylene terephthalamide (nylon 6T) and nylon 66 is a 6T / 66 (40/60 [molar ratio]) copolyamide, having an ηr2.5, a melting point of 285 ° C, and a heat of fusion of 13 cal / g. there were. The discharge state was good.

Reference Example 2 Polymerization was carried out in the same manner as in Reference Example 1, except that 16.7 kg of terephthalic acid, 2.90 kg of dodecanedioic acid, 13.16 kg of hexamethylenediamine, and 36.3 kg of AH salt were used. The obtained nylon 6T, nylon 66 and hexamethylene dodecamide (nylon 61
The terpolyamide of 2) is a 6T / 66/612 (40/55/5) terpolyamide, having an ηr of 2.4, a melting point of 293 ° C., and a heat of fusion of 7 cal / g. The discharge state was good.

Reference Example 3 Polymerization was carried out in the same manner as in Reference Example 1, except that 18 g of copper acetate (0.03 part by weight based on 100 parts by weight of the produced polymer) and 180 g of potassium iodide (0.3 part by weight based on 100 parts by weight of the produced polymer) were added. However, when the polymer was discharged, foaming of the polymer was severe, and it was very difficult to pelletize the polymer.

Reference Example 4 Polymerization was carried out in the same manner as in Reference Example 2, except that 18 g of copper acetate (0.03 part by weight based on 100 parts by weight of the produced polymer) and 180 g of potassium iodide (0.3 part by weight based on 100 parts by weight of the produced polymer) were added. However, when the polymer was discharged, foaming of the polymer was severe, and pelletization was extremely difficult.

Example 1 100 parts by weight of nylon 66 (ηr2.9), 0.15 parts by weight of copper iodide and 1.5 parts by weight of potassium iodide were used in a twin-screw extruder.
Extrusion was performed at an extrusion temperature of 280 ° C. to produce nylon 66 pellets containing a heat stabilizer. 20.3 parts by weight of the pellets, 80 parts by weight of the crystalline aromatic ring-containing polyamide produced in Reference Example 1 and 5 parts by weight of polybutylene adipate (manufactured by Sanken Kako Co., Ltd., molecular weight: about 4000) were melted at 290 ° C. by a twin screw extruder. After kneading, injection molding was performed and various properties were measured. The results are shown in Table 1.

Example 2 In the same manner as in Example 1, a nylon 66 pellet containing a heat stabilizer was produced. The pellets (20.3 parts by weight) and the crystalline aromatic ring-containing polyamide (80 parts by weight) produced in Reference Example 2 were melt-kneaded at 290 ° C. by a twin-screw extruder and injection-molded to measure various properties. The results are shown in Table 1.

Example 3 Polycaprolactone (Placcel H manufactured by Daicel Chemical Co., Ltd.)
-4) Various properties were measured in the same manner as in Example 2 except that 1.5 parts by weight was added at the time of melt-kneading at 290 ° C. using a twin-screw extruder. The results are shown in Table 1.

Example 4 Nylon 66 pellets containing a heat stabilizer were produced in the same manner as in Example 1, except that 0.5 parts by weight of copper acetate and 5 parts by weight of potassium iodide were used. Except that 21.1 parts by weight of the pellets, 80 parts by weight of the crystalline aromatic ring-containing polyamide produced in Reference Example 2, and 1.5 parts by weight of polycaprolactone,
Various properties were measured. The results are shown in Table 1.

Example 5 Nylon 66 pellets containing a heat stabilizer were produced in the same manner as in Example 1, except that 0.05 parts by weight of copper iodide and 0.5 parts by weight of potassium iodide were used. Various characteristics were measured in the same manner as in Example 3 except that the pellets were used in an amount of 20.1 parts by weight. The results are shown in Table 1.

Example 6 139.1 kg of 50% AH salt aqueous solution and 18 g of copper acetate (produced polymer 10
0.03 parts by weight with respect to 0 parts by weight and 180 g of potassium iodide (0.3 parts by weight with respect to 100 parts by weight of the produced polymer were supplied to a preheated reaction vessel, and concentrated at 120 ° C. for 5 hours. The obtained concentration was obtained. The liquid was supplied to a 400 autoclave maintained at 200 ° C., and heated to 280 ° C. under pressure.
After reacting at kg / cm ² for 2 hours, the pressure was lowered, discharged from the autoclave, cooled and solidified to form pellets. The discharge condition was good. Various characteristics were measured in the same manner as in Example 3 except that 20.3 parts by weight of the obtained nylon 66 pellet containing a heat stabilizer was used. The results are shown in Table 1.

Example 7 Nylon 66 pellets containing a heat stabilizer were produced in the same manner as in Example 1, except that 0.6 parts by weight of copper iodide and 6 parts by weight of potassium iodide were used. Various characteristics were measured in the same manner as in Example 3 except that this pellet was used in an amount of 5.3 parts by weight. The results are shown in Table 1.

Example 8 In the same manner as in Example 1, a nylon 66 pellet containing a heat stabilizer was produced. After preliminarily mixing 20.3 parts by weight of the pellet, 80 parts by weight of the crystalline aromatic ring-containing polyamide prepared in Reference Example 2, and 1.5 parts by weight of polycaprolactone, injection molding was performed and various properties were measured. The results are shown in Table 1.

Comparative Example 1 20 parts by weight of nylon 66, 80 parts by weight of the crystalline aromatic ring-containing polyamide polymerized in Reference Example 1 and 5 parts by weight of polybutylene adipate were melt-mixed at a temperature of 290 ° C. by a twin-screw extruder, followed by injection molding. Various properties were measured. The results are shown in Table 1.

Comparative Example 2 20 parts by weight of nylon 66 and 80 parts by weight of the polyamide containing a crystalline aromatic ring polymerized in Reference Example 2 were melt-mixed at a temperature of 290 ° C. by a twin-screw extruder, and injection-molded to measure various properties.
The results are shown in Table 1.

Comparative Example 3 Various properties were measured in the same manner as in Comparative Example 2, except that 1.5 parts by weight of polycaprolactone was added during melt mixing with a twin-screw extruder. The results are shown in Table 1.

Comparative Example 4 0.03 parts by weight of copper iodide and 0.3 parts by weight of potassium iodide
Various characteristics were measured in the same manner as in Comparative Example 3 except that the components were added during melt mixing by a screw extruder. The results are shown in Table 1.

Comparative Example 5 Nylon 66 pellets containing a heat stabilizer were produced in the same manner as in Example 1, except that 2.5 parts by weight of copper iodide and 25 parts by weight of potassium iodide were used. Various characteristics were measured in the same manner as in Example 3 except that this pellet was used in an amount of 25.5 parts by weight. The results are shown in Table 1.

Comparative Example 6 Nylon 66 pellets containing a heat stabilizer were produced in the same manner as in Example 1, except that 0.06 parts by weight of copper iodide and 0.6 parts by weight of potassium iodide were used. Various characteristics were measured in the same manner as in Example 3 except that this pellet was used in an amount of 50.3 parts by weight. The results are shown in Table 1.

Comparative Example 7 Various characteristics were measured in the same manner as in Comparative Example 3 except that 0.3 part by weight of IRGANOX1076 (manufactured by Ciba Geigy) was added during melt mixing with a twin-screw extruder. The results are shown in Table 1.

Comparative Example 8 0.3 parts by weight of IRGAFOSP-EPQFE (manufactured by Ciba Geigy)
Various characteristics were measured in the same manner as in Comparative Example 3 except that the components were added during melt mixing by a screw extruder. The results are shown in Table 1.

[Effects of the Invention] As described above, the polyamide resin composition of the present invention has a characteristic that the rigidity is less reduced upon absorption of water and is excellent in heat deterioration resistance, as well as mechanical strength, impact resistance and heat resistance. Therefore, it is useful as a part used in a high-temperature atmosphere for a long period of time in the automotive field and the electric field, in particular. Particularly, it is useful as a connector for an automobile.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a connector molded product used in evaluation of connector moldability in Examples and Comparative Examples. (A)
Is a side view, and (B) is a plan view seen from the right side of (A).

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 77/00-77/12 C08K 3/00-3/40

Claims (1)

(57) [Claims] 1. 70 to 98% by weight of a polyamide containing a crystalline aromatic ring
100 parts by weight of a polyamide resin comprising 2 to 30% by weight of an aliphatic polyamide, 0 to 10 parts by weight of an aliphatic polyester, 0.001 to 0.3 parts by weight of a copper compound, and an alkali metal halide
A polyamide resin composition comprising 0.005 to 2.0 parts by weight, wherein a copper compound and an alkali metal halide are previously blended with an aliphatic polyamide, and then melt-mixed with a crystalline aromatic ring-containing polyamide. Characteristic polyamide resin composition.