JPH0848872A - Polyamide resin composition and molding - Google Patents

Abstract

PURPOSE:To obtain the subject composition, excellent in plasticizing stability in injection molding, good in fluidity and mold releasability and capable of shortening the molding cycle, remarkably improving the productivity and providing a molding, good in appearance and excellent in toughness by blending a specific ester with a polyamide resin. CONSTITUTION:This composition is obtained by blending (A) 100 pts.wt. polyamide resin with (B) 0.01-10 pts.wt. ester comprising (i) a triol and/or a tetrol and (ii) a >=11C fatty acid. Furthermore, the composition is prepared by blending 100 pts. wt. resultant polyamide composition with 0.005-5 pts.wt. of (C) an inorganic nucleating agent, especially aluminum silicate, magnesium silicate or sodium phosphate having <=5mum weight-average particle diameter and/or (D) a metallic salt of a fatty acid obtained from especially a 10-25C fatty acid and a group I to III metal of the periodic table. The component (B) has preferably a <10C skeleton and the skeletal structure is preferably glycerol, mesoerythritol or pentaerythritol.

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 mainly used for injection molding, and in particular, it has a low gas generation during molding, does not impair the toughness of the material, and has a high cycle property of injection molding. Specifically, a polyamide resin composition excellent in melt fluidity during injection molding, mold releasability of a molded product after completion of injection molding, and plasticization stability of injection molding, and a polyamide resin molded product obtained by injection molding It is about.

[0002]

2. Description of the Related Art Polyamide resins are widely used as engineering plastics because they have excellent mechanical properties as well as abrasion resistance, electrical properties, chemical resistance and workability. However, with the advancement of industry, the physical properties required for polyamide resins have also improved,
And diversified.

In recent years, representative of the advanced and diversified required properties is the improvement of injection moldability in high cycle property and the improvement of mechanical properties. If the high cycle property is improved, the molding cycle can be shortened and the productivity can be improved.

The means for improving the high cycle property is to improve the crystallization rate of the polyamide resin to increase the solidification rate, to improve the mold releasability from the mold, and to improve the fluidity of the resin. Can be achieved by.

In order to improve the crystallinity of polyamide resin,
A method of adding an inorganic crystal nucleating agent represented by talc is effective. Further, for the purpose of improving releasability and plasticizing property, polyamide is added with ethylenebisamide (JP-B-44-9825) and bisureide (JP-B-48-6).
177, JP-A-53-126056), stearic acid ester (JP-A-55-31803), and aliphatic carboxylic acid substance (JP-A-54-1034).
No. 60) and the like, and a method of adding an amide compound (JP-B-49-9618) for the purpose of improving fluidity.

Further, with the diversification of application and development of polyamide resins, there is a demand for improvement in toughness. As a method of improving this, the end of polyamide is blocked by 40% or more (Japanese Patent Publication No. 3-2.
No. 3093), 55% or more blockade (Japanese Patent Publication No. 3-230)
No. 94) is proposed.

[0007]

However, the above-mentioned method aimed at improving the mold releasability and plasticizing property is not yet satisfactory in shortening the molding cycle and improving the mold releasability. Further, there is a problem that the toughness represented by the elongation is significantly reduced.

For example, when an inorganic crystal nucleating agent such as talc is added, the crystallization rate is certainly improved, but the toughness is also lowered, and after injection molding, a molded product from a mold is ejected by an ejector pin. Deforms when protruding and taking out,
There is a problem that deformation due to so-called ejection pins (protrusion deformation) is likely to occur. This problem was not necessarily ameliorated by the simultaneous addition of the inorganic crystal nucleating agent and the releasing agent.

Although the method of blocking the ends of the polyamide certainly improves the releasability, it has a problem that the toughness is low and the polymerization degree is difficult to increase so that the productivity is not good.

Therefore, the object of the present invention is to obtain a polyamide resin composition which produces less gas during molding, does not impair the toughness of the material, and has improved fluidity, mold releasability and plasticization stability during injection molding. .

[0011]

The inventors of the present invention added various compounds to a polyamide resin and examined the effects on the high cycle characteristics and the like, and then compounded an ester compound having a specific structure. Thus, the inventors have found a means for solving the above problems and arrived at the present invention.

That is, the present invention is based on polyamide resin 100.
0.01 parts by weight of an ester composed of triol and / or tetraol and a fatty acid having 11 or more carbon atoms is used per part by weight.
A polyamide resin composition containing 10 to 10 parts by weight is provided.

The present invention will be described in detail below.

Examples of polyamides used in the present invention include ring-opening polymerization products of cyclic lactams, polycondensation products of aminocarboxylic acids, and polycondensation products of dibasic acids and diamines. Specifically, nylon 6, Nylon 46, Nylon 6
6, nylon 610, nylon 612, nylon 11,
Aliphatic polyamides such as nylon 12, poly (meta-xylene adipamide), poly (hexamethylene terephthalamide), poly (hexamethylene isophthalamide), poly (tetramethylene isophthalamide)
Aromatic polyamides, and copolymers and mixtures thereof can be mentioned. Polyamides particularly suitable for the present invention include nylon 6, nylon 66, nylon 6/66,
Nylon 66 / 6T, Nylon 6 / 6T, Nylon 66
/ 6T / 6I (where T is terephthalic acid, I is isophthalic acid, and / is copolymerization).

The degree of polymerization of the polyamide is not particularly limited, but the relative viscosity (ηr) measured at 25 ° C. in 98% sulfuric acid concentration of 1% according to JIS K6810 indicates the stability of mechanical properties such as fluidity, toughness and rigidity. 1.7 or more from the point of view, 4.5 or less from the point of workability, particularly 1.8 or more and 4.0
Hereafter, it is preferably 1.8 or more and 3.5 or less. The method for polymerizing the polyamide used in the present invention is not particularly limited, and melt polymerization, interfacial polymerization, solution polymerization, bulk polymerization, solid phase polymerization, and a combination of these methods can be used. Usually, melt polymerization is preferably used.

In the ester of triol and / or tetraol used in the present invention and a fatty acid having 11 or more carbon atoms, the carbon number of the triol and / or tetraol skeleton is preferably less than 10, more preferably less than 7. is there. The carbon number of the skeleton portion here means the carbon number of the skeleton forming triol or tetraol, and a substituent that does not form the skeleton, for example, a monovalent hydrocarbon group is not included. When the carbon number is 10 or more,
The compatibility with polyamide is reduced and the dispersibility is reduced. Specific examples of the skeletal structure of triol and / or tetraol include glycerol, butanetriol, mesoerythritol, pentaerythritol, hexanetriol,
Cyclohexanetriol, phlorogricinol and the like can be mentioned, and among them, glycerol, mesoerythritol, pentaerythritol and the like can be mentioned as preferable examples.

The fatty acid forming an ester with triol and / or tetraol used in the present invention has 11 or more carbon atoms, preferably 14 or more carbon atoms. When the fatty acid used for the ester has 10 or less carbon atoms, the effect of improving the releasability and fluidity is small, which is not preferable. Specific examples of the fatty acid having 11 or more carbon atoms used in the ester include undecyl acid, lauric acid, tridecyl acid, myristic acid, pentadecylic acid, palmitic acid, heptadecyl acid, stearic acid, isostearic acid, nonadecanoic acid, oleic acid, linoleic acid, Examples include arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melissic acid, and the like, with lauric acid, stearic acid, oleic acid, arachidic acid, behenic acid, and montanic acid being particularly preferable.

In the present invention, the compounding ratio of the triol and / or tetraol consisting of fatty acid having 11 or more carbon atoms is 0.01 to 10 parts by weight, preferably 0.05 to 100 parts by weight with respect to 100 parts by weight of the polyamide resin. It is used in an amount of 5 parts by weight, more preferably 0.05 to 2 parts by weight. If the amount is less than 0.01 parts by weight, no improvement effect such as releasability is observed, and if the amount exceeds 10 parts by weight, fluidity,
Although the releasability is improved, it is not preferable because it adversely affects the plasticization stability and the surface appearance.

Furthermore, by adding these inorganic nucleating agents and fatty acid metal salts together to the polyamide resin composition of the present invention, the high cycle property is synergistically improved,
The toughness of the molded product, which is a drawback of the inorganic crystal nucleating agent and the fatty acid metal salt, is also greatly improved.

As the inorganic crystal nucleating agent used in the present invention, known ones can be used, such as barium sulfate, tricalcium phosphate, calcium carbonate, sodium phosphate, calcium fluoride (eg, fluorite), aluminum silicate or magnesium silicate. Acid salts are preferably used. Kaolin is exemplified as the aluminum silicate, and talc is exemplified as the magnesium silicate. Mica is exemplified as the aluminum-magnesium silicate. In particular, aluminum silicate, magnesium phosphoric acid, aluminum-magnesium silicate and sodium silicate are preferably used in the present invention. The addition of the nucleating agent increases the crystallization rate, which is observed. Although not particularly limited, the weight average particle diameter of the nucleating agent is 5 μm or less, preferably 3 μm or less, more preferably 2 μm or less, and most preferably 1 μm or less. If the particle size is large, the toughness is reduced, which is not preferable.

As the fatty acid metal salt to be preferably blended, a fatty acid metal salt obtained from a fatty acid having 10 to 25 carbon atoms, particularly 12 to 22 carbon atoms and a metal of Group I to III of the Periodic Table is preferably used. To be

Examples of fatty acids include stearic acid, balmitic acid, oleic acid, aragic acid and behenic acid, and examples of metals include zinc, calcium, lithium, aluminum, barium and sodium.
Mention may be made of magnesium and the like.

Preferred examples of the fatty acid metal salt include zinc stearate, calcium stearate, lithium stearate, aluminum stearate, barium stearate, sodium stearate, magnesium stearate, and the like.

In the present invention, when the inorganic crystal nucleating agent and the fatty acid metal salt are used, the compounding amount thereof is 0.001 to 5 parts by weight in total with respect to 100 parts by weight of the polyamide resin composition comprising the polyamide resin and the ester. , Preferably 0.
It is used in the range of 005 to 3 parts by weight, more preferably 0.01 to 2 parts by weight. By using these, good crystallinity is obtained, solidification is accelerated, and the molding cycle can be shortened. If the amount exceeds 5 parts by weight, the obtained material becomes brittle, which is not preferable.

Similarly, blending of a bisamide typified by ethylenebisstearylamide (EBS) is also effective for high cycle production. Examples of such amide compounds include N, N'-stearyl stearic acid amide, N, N
Examples thereof include N'-oleyl oleic acid amide, stearic acid blocked nylon 2.10 oligomer and EBS.

The method for producing the polyamide resin composition of the present invention is not particularly limited, and it is a method of adding polyamide during the production by polymerization, a method of adhering to the dry blend and pellet surface after the polymerization, an inorganic crystal nucleating agent and a fatty acid. A method of adding a metal salt at the time of polymerization of polyamide and adding it after ester polymerization, which is a feature of the present invention, a method of melt-kneading each material with a polyamide resin, an ester and an inorganic crystal nucleating agent, which are features of the present invention, and It may be produced by any method such as a method in which concentrate pellets of a fatty acid metal salt are prepared by melt-kneading, and the concentrate pellets are dry-blended. The melt kneading may be carried out by a known method, for example, using a Banbury mixer, a mixing roll, a single-screw or twin-screw extruder, and the like, to obtain pellets of the mixture.

The polyamide resin composition of the present invention contains other components such as other polyamide components, copper compounds, heat stabilizers, weathering agents, inorganic fillers, reinforcing agents, and antioxidants to the extent that the moldability and physical properties are not impaired. Agents, impact modifiers, pigments, lubricants, flame retardants, etc. can be added and introduced.

The composition obtained according to the present invention is a resin composition having new characteristics lacking in the polyamide resin without impairing the excellent characteristics originally possessed by the polyamide resin. It is most suitable for injection molding applications due to its good resistance to protrusion deformation. Products obtained by such injection molding include switches, ultra-small slide switches, DIP switches, switch housings, lamp sockets, binding bands, connectors, connector housings, connector shells, IC sockets, coil bobbins, bobbins. Covers, relays, relay boxes, condenser cases, motor internal parts, small motor cases, gear cams, dancing pulleys, spacers, insulators, fasteners, buckles, wire clips, bicycle wheels, casters, terminal blocks, power tool housings , Insulation part of starter, canister, fuse box, air cleaner case, air conditioner fan, terminal housing, wheel cover, bearing retainer, cylinder head cover Intake manifolds, water pipe impellers, clutch release bearing hubs, speaker diaphragms, heat-resistant containers, microwave oven parts, rice cooker parts, printer / ribbon guides, etc. Examples include electrical product parts, computer-related parts, facsimile / copier-related parts, and other machine-related parts, which are useful for various other purposes.

[0029]

The present invention will be described in more detail with reference to the following examples. In addition, about each evaluation, it measured according to the method described below.

(1) Toughness test Rod-shaped molded product (width 10 mm, length 150 mm, thickness 1.5)
(mm) was bent at −10 ° C. at an angle of 180 °, and 100 pieces were bent, and the number of breakages was obtained. (2) Flowability Injection molding machine (cylinder temperature: 245 for nylon 6
℃, Nylon 66 280 ℃, mold temperature: 80 ℃), using a 1mm thick flow length test piece resin pressure 1000kg / cm2
And the spiral flow length of the test piece was measured. (3) Releasability Injection molding machine (cylinder temperature: 245 for nylon 6
℃, nylon 66 280 ℃, mold temperature: 80 ℃), using a pressure sensor box molded product (length 100 mm, width 60 mm, height 25 mm, wall thickness 2 mm) is molded, The force at that time was measured by a pressure sensor, and the average of 10 shots was shown as the releasing force. (4) Protrusion deformation resistance Injection molding machine (cylinder temperature: 240 for nylon 6)
℃, nylon 66 280 ℃, mold temperature: 80 ℃), using hat-molded products (upper 2mmφ, lower 3mmφ, 16 pieces placed in the mold), average deformation at the time of protrusion by the ejector pin The injection time at which the number became 0.5 / 16 was measured. (5) Plasticization stability Injection molding machine (cylinder temperature: 240 for nylon 6)
C., 280.degree. C. for nylon 66) was used, and the time until the pellet was bitten into the 60 mm cylinder was measured at a screw rotation speed of 130 rpm, and the variation was expressed as a standard deviation. The smaller this value, the better the plasticization stability. (6) Presence or absence of gas generation When a polyamide resin composition was injection-molded, the presence or absence of silver streak caused by the gas generated from the composition was visually judged.

Examples 1 to 8 Nylon 6 which is a polyamide resin (indicated as N6 in the table)
(Η r = 2.45) and nylon 66 (indicated as N66 in the table) (η r = 2.55), the following branched polyester oligomers (A and B), an inorganic crystal nucleating agent having a weight average particle diameter of 1.2 μm, and a fatty acid metal After dry-blending the salt in the amounts shown in Table 1, kneading with a 30 mmφ twin-screw extruder, drying and molding,
A test piece was obtained. Table 1 shows the evaluation results.

[Ester Compound] A: Tristearin B: Pentaerythritol tetrastearyl ester These materials have a good surface appearance, and as is clear from Table 1, they have good fluidity and releasability, and have a plasticizing time. Variation is small. Also in terms of mechanical properties, the bending resistance (toughness) was good.

Further, those to which the inorganic crystal nucleating agent and the fatty acid metal salt were added were further excellent in releasability and ejection deformability.

Comparative Examples 1 and 2 (Use of Ester Compound which is Characteristic of the Present Invention) The same ester compound (C,
D), the inorganic crystal nucleating agent, and the fatty acid metal salt in the amounts shown in Table 1,
Test pieces were obtained by the same method as in the example, and the same evaluation was performed.

[Ester Compound] C: Pentaerythritol Tetracapryl Ester D: Ditridecyl Phthalate Ester In both Comparative Examples 1 and 2, silver streaks were generated on the surface of the molded product, and bending bending resistance (toughness) was compared to Example 2. ), Releasability and protrusion deformability were not sufficient.

Comparative Examples 3 to 10 Evaluations were carried out in the same manner as in the Examples, but those with a large amount of the ester compound (Comparative Example 3) exhibited fluidity, releasability, and
Although the extrusion resistance was good, the plasticization time varied widely, silver streaks were slightly generated on the surface of the molded product, and the surface appearance was not sufficient. In the case where the ester compound was not added (Comparative Example 4), the appearance of the molded product was good, but the bending resistance (toughness) was not sufficient as compared with the composition of the present invention, and the flowability and the releasability were good. However, the extrusion deformation resistance was not good. The one containing a large amount of the inorganic crystal nucleating agent and the fatty acid metal salt (Comparative Example 5) had good fluidity, mold releasability, extrusion deformability, and surface appearance, but the bending resistance (toughness) was not sufficient. The one containing only the inorganic crystal nucleating agent (Comparative Example 6) had a good surface appearance,
No improvement in bending bending resistance (toughness) was observed, and neither mold releasability nor extrusion deformation resistance was satisfactory. The one containing EBS instead of the ester compound (Comparative Example 7) is
It cannot be said that the surface of the molded product is good, and the bending resistance (toughness),
It cannot be said that the mold releasability and the protruding deformability are good.
Also, the plasticization stability was not sufficient. The compound containing EBS and an inorganic crystal nucleating agent instead of the ester compound (Comparative Example 8) was not sufficient in bending bending resistance (toughness), releasability, resistance to protrusion deformation, and surface appearance. The composition containing only the fatty acid metal salt (Comparative Example 9) had a good surface appearance, but was not good in bending bending resistance (toughness), fluidity, mold release property, and extrusion deformation resistance. The composition containing EBS and a fatty acid metal salt instead of the ester compound (Comparative Example 10) had a good surface appearance, but was not sufficient in bending bending resistance (toughness), releasability and extrusion deformation resistance. It was

[0037]

[Table 1]

[0038]

INDUSTRIAL APPLICABILITY The polyamide composition of the present invention has excellent plasticization stability during injection molding, good flowability and mold releasability, can shorten the molding cycle, and can remarkably improve the productivity. it can. In addition, the obtained molded product can have good appearance and excellent toughness.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area // B29K 77:00

Claims (8)

[Claims] 1. A polyamide resin composition comprising 100 parts by weight of a polyamide resin and 0.01 to 10 parts by weight of an ester composed of triol and / or tetraol and a fatty acid having 11 or more carbon atoms. 2. A polyamide resin composition comprising 100 parts by weight of the polyamide resin composition of claim 1 and 0.005 to 5 parts by weight of an inorganic crystal nucleating agent and / or a fatty acid metal salt. 3. A polyamide resin composition, wherein the inorganic crystal nucleating agent according to claim 2 is aluminum silicate, magnesium silicate or sodium phosphate. 4. A polyamide resin composition, wherein the skeleton carbon number of the triol and / or tetraol of claim 1 is less than 10. 5. A polyamide resin composition, wherein the skeleton structure of the triol and / or tetraol of claim 1 is glycerol, mesoerythritol or pentaerythritol. 6. A polyamide resin composition, wherein the weight average particle diameter of the inorganic crystal nucleating agent according to claim 2 is 5 μm or less. 7. A polyamide resin composition, which is a fatty acid metal salt obtained from a fatty acid metal salt of claim 2 having a carbon number of 10 or more and less than 25 and a metal of Group I to III of the periodic table. Stuff. 8. A molded article obtained by injection molding the polyamide resin composition according to claim 1.