JP5080718B2 - Polyamide resin composition - Google Patents

Description

  The present invention relates to a polyamide resin composition. More specifically, the present invention relates to a polyamide resin composition suitable for producing a molded article having a binding band or a hinge structure.

  Polyamide resins are used in various applications including parts for automobiles and electrical / electronic fields. The main application of the unreinforced polyamide resin composition in which no filler, glass fiber, or the like is blended is a molded product having a binding band (see FIG. 1 and FIG. 2) and a hinge structure (see FIG. 3, FIG. 3 and FIG. 3). 4), and particularly connectors used in the automobile and electrical / electronic fields.

  If the raw material resin is a polyamide resin with high rigidity and the molded product has a thin binding band part or hinge structure part, it is easy to bend when the thin part is bent and deformed. It has been devised to make it flexible. However, even when the water absorption treatment is performed, when used in a low temperature environment, the flexibility is insufficient, and there has been a problem that the thin portion such as the hinge structure breaks.

  In order to prevent breakage of a thin portion such as a hinge structure portion, improvement studies have been made on polyamides 6 and 6 having high rigidity or a flame retardant grade. In order to impart flexibility to the raw material resin, a method of copolymerizing a component imparting flexibility with a highly rigid polyamide resin, a method of blending a polyolefin-based resin or a flexible polyamide resin, and the like have been proposed.

  In addition, for the purpose of improving the low-temperature breakability of the binding band, a resin composition to which modified polyolefin is added (see Patent Document 1), a resin composition to which potassium iodide is added (see Patent Document 2), preferably polyamide 6 · A polyamide resin composition in which a lubricant and a crystal nucleating agent are blended in a mixture of 6 and polyamide 6 (see Patent Document 3) has been proposed.

In addition, the molded product having the binding band part and the hinge structure part has a thickness difference between the hinge structure part and the other part of the molded product, so that the molded product is released from the mold when the molded product is manufactured. Trouble (deformation failure) may occur. Many attempts have been made to improve such releasability. For example, a method of preparing a resin composition containing one or more compounds selected from the group consisting of barium stearate, barium laurate, and aluminum stearate, a salt of an aliphatic carboxylic acid having 10 to 20 carbon cords, and carbon In addition to a method of preparing a resin composition containing an aliphatic carboxylic acid having a number of 22 or more, or a derivative thereof, a powder of boron nitride having a particle size of 10 μm or less and a derivative of an aliphatic carboxylic acid having a carbon number of 15 or more Polyamide resin composition (see Patent Document 4). Furthermore, a polyamide resin having a hydrocarbon group having 6 to 22 carbon atoms at the molecular end (see Patent Document 5) has been proposed.
JP-A-7-62233 JP-A-8-73736 JP-A-10-204290 JP 7-82474 A JP 61-163935 A

  The present invention has been completed as a result of intensive studies in order to solve the above-described conventional drawbacks. That is, an object of the present invention is to provide a polyamide resin composition suitable for the production of a bundling band that is excellent in releasability during production and hardly breaks or a molded product having a hinge structure.

  In order to solve the above problems, in the present invention, in a polyamide resin composition in which an aluminum salt of an aliphatic carboxylic acid having 12 to 22 carbon atoms is blended with a polyamide resin, the polyamide resin has 6 to 6 carbon atoms at the terminal. There is provided a polyamide resin composition having 22 hydrocarbon groups, wherein the number of hydrocarbon groups is 40 to 100% of the total terminal groups of the polyamide resin.

The present invention is as described in detail below, and has the following particularly advantageous effects, and its industrial utility value is extremely large.
1. The polyamide resin composition according to the present invention is excellent in releasability during production of a binding band having a thin portion, a molded product having a hinge structure portion, and the like, and hardly breaks.
2. A molded product having a binding band and a hinge structure part obtained from the polyamide resin composition according to the present invention exhibits a low-temperature breakage preventing effect with an excellent thin part.
3. The molded product having a binding band and a hinge structure obtained from the polyamide resin composition according to the present invention stabilizes the quality of products used in the automobile and electrical / electronic fields, and contributes to higher functionality of parts. To do.

Hereinafter, the present invention will be described in detail.
The polyamide resin constituting the resin composition according to the present invention refers to polyamides obtained by polycondensation of a lactam having three or more members, a polymerizable ω-amino acid, a dibasic acid and a diamine. Specifically, polymers such as ε-caprolactam, aminocaproic acid, enanthractam, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone, α-piberidone, hexamethylenediamine, nonamethylene Obtained by polycondensation of diamines such as diamine, undecamethylenediamine, dodecamethylenediamine, and metaxylylenediamine with dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid, sebacic acid, dodecane dibasic acid, and glutaric acid. Polymers, or copolymers thereof, such as polyamides 4, 6, 7, 8, 11, 12, 6 · 6, 6 · 9, 6 · 10, 6 · 11, 6 · 12, 6T, 6 / 6 · 6, 6/12, 6 / 6T and the like. Here, “•” means a combination of monomers, and “/” means a copolymer. Among these, polyamide 6, polyamide 6, 6 or a copolymer thereof is particularly preferable, and polyamide 6 is particularly preferable. A preferred viscosity number of the polyamide resin is a value measured in accordance with ISO 307 in the range of 90 to 190 ml / g, particularly preferably in the range of 99 to 138 ml / g.

  The raw material polyamide resin is a polyamide resin having a hydrocarbon group having 6 to 22 carbon atoms at the terminal, and the number of hydrocarbon groups is 40 to 100% of the total terminal groups of the polyamide resin. Such polyamide resins include monocarboxylic acids having 7 to 23 carbon atoms, monoamines having 6 to 22 carbon atoms, and / or diamines having 2 to 22 carbon atoms, or monoamines having 6 to 22 carbon atoms. It is a polyamide resin having a terminal end sealed obtained by polymerizing it and a dicarboxylic acid having 3 to 24 carbon atoms in combination. As a combination of these end group blocking agents, a combination of stearic acid and octadecylamine, stearic acid and hexamethylenediamine, stearic acid, adipic acid and stearylamine is preferable. The ratio of the hydrocarbon group having 6 to 22 carbon atoms in all terminal groups is preferably 50% or more, more preferably 70% or more.

  The polyamide resin is blended with an aluminum salt of an aliphatic carboxylic acid having 12 to 22 carbon atoms. Among the aluminum salts of aliphatic carboxylic acids, aluminum stearate and aluminum laurate are preferred. The amount of the aliphatic carboxylic acid aluminum salt is in the range of 0.01 to 1% by weight of the polyamide resin composition. If the blending amount is less than 0.01% by weight, the effect of improving the low-temperature breakability of the thin part of the molded product will not be exhibited. descend. In the above range, 0.03 to 0.7% by weight is preferable, and 0.05 to 0.5% by weight is particularly preferable.

  In order to supplement the effect of improving the release property of the aliphatic carboxylic acid aluminum salt, another release agent is added to the polyamide resin in an amount of 0.005 to 0.5% by weight, more preferably 0.01 to 0.2%. It can mix | blend in the range of weight%. Other mold release agents include paraffin wax, polyethylene wax, fatty acids, fatty acid esters, bisfatty acid amides, and the like, and fatty acid amides are particularly preferred from the viewpoint of compatibility with polyamide. Specific examples of the bis fatty acid amides include ethylene bis stearic acid amide and methylene bis stearic acid amide.

  In addition, other types of resins and various resin additives can be blended with the polyamide resin composition as long as the object of the present invention is not impaired. Examples of other resins include polyolefin resins, modified polyolefin resins, polyester resins, polyester elastomers, polyamide elastomers, and polystyrene resins. Examples of the resin additive include stabilizers such as hindered phenols, heat resistance improvers such as copper halide compounds, flame retardants such as melamine cyanurate, pigments, dyes, and antistatic agents. However, nucleating agents and inorganic fillers that promote crystallization are not blended unless there is a special purpose. Examples of such nucleating agents and inorganic fillers that have a remarkable crystallization promoting effect and are not preferable for blending include talc, wollastonite, kaolin, calcined kaolin, mica, zeolite, and boron nitride.

  As a method for preparing the polyamide resin composition according to the present invention, (1) a predetermined amount of a raw material polyamide resin and an aliphatic carboxylic acid aluminum salt having 12 to 22 carbon atoms are weighed and, if necessary, other resins and resins. A method of adding additional additives, etc., and mixing with a blender to make a dry blend, (2) preparing a masterbatch containing a large number of aliphatic carboxylic acid aluminum salts having 12 to 22 carbon atoms, this masterbatch Or a method of dry blending the raw material polyamide resin into a raw material polyamide resin, or (3) a method of melting and pelletizing the dry blend of (1) or (2) with a melt kneader such as an extruder. The dry blended product or pellet is produced by producing an intended binding band (see below, FIG. 1 and FIG. 2), a molded product having a hinge structure (see below, FIG. 3 and FIG. 4), etc. by an injection molding method. It can be used as a raw material resin material.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited to the following description examples, unless the summary is exceeded.

The types and characteristics of the components used in the examples and comparative examples are as follows.
1. Polyamide resin:
(1) PA-1: Polyamide 6 wherein 85% of all end groups are sealed by introducing stearic acid and octadecylamine, and have a viscosity number of 118 ml / g.
(2) PA-2: Polyamide 6, in which 40% of all end groups are sealed by introducing acetic acid and have a viscosity number of 118 ml / g.

2. Fatty acid metal salt or lubricant (3) Al: Aluminum stearate (manufactured by NOF Corporation).
(4) Ca: calcium stearate (manufactured by NOF Corporation).
(5) Ba: Barium stearate (manufactured by NOF Corporation).
(6) Mg: Magnesium stearate (manufactured by NOF Corporation).
(7) EBS: Tylene bis stearamide (manufactured by Kao Corporation).

Evaluation tests of resin compositions and molded products in Examples and Comparative Examples are as described below.
(A) Mold release test: Using an injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd., model: PS40), a binding band having the structure shown in FIGS. 1 and 2 and the structure shown in FIGS. 3 and 4 A molded product having a shape was obtained by continuously molding 120 shots by the method described below. The obtained molded product is evaluated by visually observing the occurrence of mold release troubles such as breakage and cracking of the thin portion (see FIG. 1) or the hinge structure portion (see FIG. 3) of the binding band. The case where the occurrence of the release trouble was not recognized was judged as ◯, the case where the trouble was found was judged as ×, and the evaluation results are shown in Table 2.

  1 is a schematic side view of a binding band manufactured in Examples and Comparative Examples, and FIG. 2 is a schematic plan view. FIG. 3 is a schematic side view for explaining an implementation state of a low-temperature breakability test for a binding band, FIG. 4 is a schematic diagram of a molded product having a hinge structure manufactured in Examples and Comparative Examples, and FIG. FIG. 6 is an enlarged schematic view of the hinge structure portion of the molded product shown in FIG. 4, and FIG. 1 to 3, 1 is a binding band, 2 is a band part, 3 is a band part insertion hole, 4 is a protrusion, 5 is a binding part, in FIGS. 4 to 5, 6 is a molded product, and 7 is a thickness. It is a hinge structure part comprised with a 0.4 mm film.

(B) Low temperature breakability (band): After the binding band shown in FIG. 1 and FIG. 2 manufactured by the method described in (a) above is left in a thermostatic bath at −25 ° C. for 8 hours or more, 3, the band portion 2 is passed through the band insertion hole 3 and the band insertion hole 3 is held with one hand, while the band portion 2 is strongly pulled in the direction of the arrow in FIG. This is a method of visually observing whether or not cracks have occurred. The test was conducted on 20 binding bands, and the number of cracks observed is shown in Table-2. The binding band 1 is almost always cracked in the binding part 5.

(C) Low temperature breakage (hinge): After 20 pieces of molded products (absolutely dried products) having the hinge structure shown in FIGS. 3 and 4 were left in an atmosphere of −35 ° C. for 8 hours or longer, FIG. As indicated by the dotted line, this is a method of visually observing whether the hinge structure part is bent once or bent at an angle of 90 degrees. Table 20 shows the number of cracks observed in the hinge structure portion among the 20 molded products.

[Example 1 to Example 2, Comparative Example 1 to Comparative Example 7]
Polyamide resin, fatty acid metal salt and other additives were weighed in the proportions listed in Table 1 and mixed with a blender. Using the obtained dry blend as a raw material, a molded product 6 having a binding band 1 shown in FIGS. 1 and 2 and a hinge structure shown in FIGS. , Model: PS40), the resin temperature was 250 ° C., the injection time was 3 seconds, the cooling time was 7 seconds, and the total cycle was 10 seconds. With respect to the molded product 6 having the binding band 1 and the hinge structure portion obtained, the releasability during the production of the molded product and the low-temperature breakability of the molded product were evaluated according to the above evaluation method. The evaluation results are shown in Table-2.

The following becomes clear from Table-1 and Table-2.
1. The polyamide resin composition according to the present invention is excellent in releasability at the time of producing a molded product having a binding band and a hinge structure, and hardly breaks (see Examples 1 to 2).
2. The thin-walled part of the molded article having a binding band and a hinge structure part obtained from the polyamide resin composition according to the present invention exhibits an excellent low-temperature breakage preventing effect (see Examples 1 to 2).
3. On the other hand, even if the polyamide resin satisfies the requirements of claim 1, those that do not contain an aluminum salt of an aliphatic carboxylic acid having 6 to 22 carbon atoms have both mold release properties and low temperature breakage prevention properties. Inferior (see Comparative Example 1).
4). Even if the polyamide resin satisfies the requirement of claim 1 and does not satisfy the requirement, it does not contain an aluminum salt of an aliphatic carboxylic acid having 6 to 22 carbon atoms. Comparative Examples 2 and 3)
5. On the other hand, even if the polyamide resin satisfies the requirements of claim 1, a compound containing a fatty acid metal salt other than an aluminum salt of an aliphatic carboxylic acid having 6 to 22 carbon atoms or a lubricant is releasable. Is improved, but the resistance to breakage at low temperatures is poor (see Comparative Examples 4 to 7).

  Since the molded product according to the present invention has an excellent effect of preventing the low temperature breakage of the thin-walled portion, it is used as a molded product having a binding band and a hinge structure portion used in the automobile and electric / electronic fields, and its quality. The reliability is improved.

It is the plane schematic diagram of the binding band which performed the evaluation test of low temperature breakability (band). It is a side view of the binding band shown in FIG. It is a schematic side view when explaining the implementation state of the low-temperature breakability test of the binding band. It is the plane schematic diagram of the molded article which has the hinge structure part which performed the evaluation test of the low temperature breakability (hinge). It is an enlarged view of the hinge structure part of the molded article shown in FIG. It is a side schematic diagram at the time of explaining the implementation state of the cold breakability of a hinge structure part.

Explanation of symbols

1: Bundling band 2: Band part 3: Band part insertion hole 4: Projection 5: Bundling part 6: Molded product 7: Hinge structure part

Claims (5)

  In a polyamide resin composition in which an aluminum salt of an aliphatic carboxylic acid having 12 to 22 carbon atoms is blended with a polyamide resin, the polyamide resin has a hydrocarbon group having 6 to 22 carbon atoms at its end, and this hydrocarbon A polyamide resin composition characterized in that the number of groups is 40 to 100% of all terminal groups of the polyamide resin.   The polyamide resin composition of Claim 1 whose compounding quantity of the aluminum salt of aliphatic carboxylic acid is 0.01 to 1 weight% of a polyamide resin composition.   The polyamide resin composition according to claim 1 or 2, further comprising a bis-fatty acid amide compound in the polyamide resin.   The polyamide resin composition of Claim 3 whose compounding quantity of a bis-fatty acid amide compound is 0.005-0.5 weight% of a polyamide resin composition.   The polyamide resin composition according to any one of claims 1 to 4, wherein the polyamide resin is polyamide 6.

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