JP4480984B2 - Chair parts made of metallic polyamide resin - Google Patents

Description

  The present invention relates to a metallic polyamide resin composition for chair parts. Specifically, the present invention relates to a metallic polyamide resin composition suitable for a chair leg excellent in gloss and mechanical strength.

Polyamide resins are used in the form of injection molded articles, particularly for structural parts, electrical parts, automobile parts, etc., because of their moldability and excellent mechanical properties. In particular, polyamide 66/6 and polyamide 6/66 copolymers and polymer blends reinforced by adding glass fibers are widely used in fields where the appearance of molded products is required. For example, in the field of office furniture, as a resin material for a chair, particularly as a resin material for a chair leg, a reinforced polyamide resin to which an inorganic reinforcing material such as glass fiber is added is suitably used from the viewpoint of mechanical strength. .
In recent years, especially in the field of chairs for office furniture, the design of the legs has been regarded as important. From the complicated resin legs with the conventional rib structure, the thick and simple shape without the rib structure, and There is a tendency to desire a slim and beautiful resin leg. In addition, there is a high market need for a metallic feel (metallic tone) on the resin legs in order to give a high-class feel. However, there is no known polyamide resin composition having sufficient mechanical strength required for chair parts, having a smooth surface even with a thick wall, and having a good metallic appearance.

In the following Patent Document 1, a granule obtained by granulating a composition of polyamide resin and glass fiber is mixed with a granule obtained by granulating a composition of polyamide resin and aluminum powder. A molding material for a molded article having a mellic appearance is disclosed. The resin material is described as being capable of producing a polyamide resin molded article having a metallic appearance with excellent strength, rigidity and heat resistance.
However, with the resin composition, a good metallic tone could not be obtained in a chair component having a thick resin.

Patent Document 2 listed below discloses a resin composition comprising a polyamide resin, glass fiber, metal powder, and a pearl pigment, and containing a pearl pigment at least 1.5 times the metal powder. The resin composition has a bright metallic color tone, excellent color retention during heat aging, and is described as being useful in various applications. However, the resin composition has poor mechanical strength as a molding material for chairs. It was enough.
In any of the patent documents, there is no description that a chair component having a large resin thickness can be used and a good metallic tone can be obtained.
In general, when the resin thickness of the molded product exceeds 5 mm, it becomes difficult to obtain a molded product with a smooth surface and a good metallic appearance, and it still has a metallic appearance with a good thickness and surface appearance. However, the present situation is that no reinforced polyamide resin composition suitable for a chair part satisfying mechanical strength has been proposed.
Japanese Patent No. 2718083 JP-A-11-293106

The present invention comprises a metallic polyamide resin composition suitably used as a molding material for chair parts having a good surface gloss and excellent mechanical strength, and a thick part of 5 mm or more comprising the resin composition. The object is to provide chair parts, in particular chair legs.

As a result of intensive investigations to obtain a polyamide resin composition that exhibits a metallic appearance with a smooth surface and excellent mechanical strength in a thick-walled molded article, the inventor crystallizes from a molten state. The present inventors have found that a resin composition in which a polyamide resin having a specific temperature (Tc) within a specific range, an inorganic reinforcing material, and a metal powder are combined is effective, and based on this finding, the present invention has been made.
That is, the present invention
[ 1 ] (a) One or more polyamide resins 32 selected from polyamide 6, polyamide 66 and polyamide 6 / polyamide 66 copolymer having a temperature (Tc) of crystallization from a molten state of 180 to 210 ° C. ～84.8 wt%, consisting of (b) an inorganic reinforcing material 15 to 65% by weight, (c) contains a metal powder 0.2-3% by weight of the average particle diameter 10~90μm cuttlefish Tarik tone polyamide resin composition A chair part having a thick part of 5 mm or more .

[2] (c) an average particle metal powder diameter 10~90μm is flaky, characterized in that an aluminum powder [1] the chair article according to,

[3] (a) the temperature at the time of crystallization from the molten state of the polyamide resin (Tc), characterized in that a 180-195 ° C. [1] or [2] the chair article according to,
[ 4 ] The chair part according to any one of [1] to [3 ], wherein the chair part is a chair leg,
It is.

  The present invention provides a polyamide resin composition having an excellent metallic tone even if it is a polyamide resin containing an inorganic reinforcing material. Even if it is a thick molded product such as a chair part, particularly a chair leg, the surface property is provided. It has excellent metallic tone. In addition, since the chair component using the polyamide resin composition does not require a painting process, it has an effect of being economical and having a low environmental load that can be recycled.

Hereinafter, the present invention will be described in detail.
The (a) polyamide resin used in the present invention is a crystalline aliphatic polyamide or aromatic polyamide, preferably polyamide 6, polyamide 66, polyamide 6T, polyamide 6I, or at least selected from them. Two or more kinds of copolymers or polymer blends can be mentioned. Among these polyamide resins, a polyamide resin having a Tc of 180 to 210 ° C, more preferably 180 to 195 ° C.
Tc as referred to in the present invention is measured with a differential scanning calorimeter (DSC), is heated to 300 ° C. at 20 ° C./min, held for 3 minutes, and then the peak temperature of crystallization when the temperature is lowered to 100 ° C. Defined by

When the Tc exceeds 210 ° C., the inorganic reinforcing material tends to appear on the surface of the molded product, and it becomes difficult to obtain a smooth surface. This phenomenon becomes prominent when a thick molded product (thickness of 5 mm or more) is molded, and the value of Tc is very important.
When the thickness of the molded product is small, the flow rate when the molten resin flows through the mold is high, and the molten resin is molded while being sufficiently pressed against the mold surface, so the inorganic reinforcing material tends to appear on the surface of the molded product. Therefore, it is easy to obtain a molded product having a relatively smooth surface regardless of Tc, and when the thickness of the molded product is thick, the flow rate of the molten resin becomes slow, so that the molten resin is solidified before being sufficiently pressed against the mold surface. It is estimated that the inorganic reinforcing material is likely to appear on the surface of the molded product.

Further, if the Tc is lower than 180 ° C., the solidification speed of the molded product surface becomes too slow, and the molded product is likely to be deformed when the molded product is ejected. Time is unpreferable.
The molecular weight of the polyamide resin used in the present invention is not particularly specified, but is preferably formic acid solution viscosity (JIS K 6933) 15 to 65, more preferably 20 to 60. When this formic acid solution viscosity is too higher than this region, the fluidity is deteriorated and the surface glossiness of the molded product is lowered. If it is too low, the molded product becomes brittle, and sufficient strength cannot be maintained.
The amount of polyamide resin contained in the polyamide resin composition of the present invention is required to be 32 to 84.8% by weight, and preferably 43 to 79.8% by weight. When the amount of the polyamide resin is in the range of 32 to 84.8% by weight, a molded product having good surface gloss and sufficient mechanical strength can be obtained.

The inorganic reinforcing material (b) used in the present invention includes generally used glass fiber, glass flake, carbon fiber, metal fiber, talc, mica, unfired clay, acicular wollastonite, zinc oxide whisker, and irregular shape. Although carbon cal-silica, apatite, etc. are used and are not subject to any limitation, glass fiber is preferable from the viewpoint of mechanical strength, and glass fiber having an average diameter of 9 to 14 μm and an aspect ratio of 21 to 56 is more preferable. .
(B) The compounding quantity of an inorganic reinforcement material is 15 to 65 weight%, Preferably it is 20 to 55 weight%. From the viewpoint of the strength, rigidity and impact of the molded product, the blending amount of (b) inorganic reinforcing material needs to be 15% by weight or more, while (b) the blending amount of inorganic reinforcing material is 65% by weight. If it exceeds the upper limit, the fluidity at the time of molding deteriorates, and the inorganic reinforcing material tends to appear on the surface of the molded product, so that the glossiness is lowered and a good metallic tone cannot be obtained.

Examples of the (c) metal powder used in the present invention include copper powder, stainless steel powder, molybdenum powder, aluminum powder, and the like, and powder obtained by surface-treating metal with plating or the like can also be used. Of these, flaky aluminum powder is preferred from the viewpoint of facilitating metallic tone. The metallic tone greatly depends on the particle size of the metal powder, and it is necessary that the metal particle has an average particle size of 10 to 90 μm, and the average particle size is preferably 40 to 90 μm, from the viewpoint of easy metallic tone. When the average particle size is less than 10 μm, the glittering feeling in metallic tone is impaired, and when it exceeds 90 μm, the feeling of glare is too strong, which is not preferable.
The compounding amount of the metal powder is 0.2 to 3% by weight, preferably 0.2 to 2% by weight, and more preferably 0.2 to 0.8% by weight. Below this range, good metallic tone cannot be obtained, while above this range, the strength, impact properties, etc. of the molded product are impaired.

Moreover, the glossiness of the surface of the molded article obtained by using the metallic polyamide resin composition of the present invention, that is, the value of 60 degree gloss (glossiness) is preferably 60 or more, more preferably 70 or more. In the present invention, 60 degree gloss is measured using an FE-120 injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd.), a mold surface temperature of 80 ° C., a resin temperature of 280 ° C., a holding pressure of 400 kgf / cm ² , and a screw. Using a flat plate 120mm long x 80mm wide x 10mm thick formed by a side gate with a forward speed of 100mm / second, gate size height 3mm x width 6mm, the surface area φ45mm of the flat plate is 60 ° mirror surface as defined in JIS Z8741 It was measured by a glossiness measurement method.
In the polyamide resin composition of the present invention, a heat stabilizer, a weathering agent, an antioxidant, a flame retardant, a lubricant, a release agent, a nucleating agent, an inorganic pigment, a dye, an elastomer, and the like are added to the extent that the purpose is not impaired. Things are also possible.

The metallic polyamide resin composition of the present invention is obtained by melt-kneading the constituent components (a) polyamide resin and (b) inorganic reinforcing material using an ordinary twin screw extruder, and adding the inorganic reinforcing material (A) reinforcement It is possible to obtain a polyamide resin composition, and then mix a predetermined amount of (c) metal powder and melt and knead it with an extruder. ) Metal powder is mixed and melt kneaded in an extruder (B) to obtain a master batch, and the remaining polyamide resin and (b) inorganic reinforcing material are melt kneaded using a normal twin screw extruder. Then, after obtaining the (A) reinforced polyamide resin composition to which the inorganic reinforcing material is added, the (B) master batch is added to the (A) reinforced polyamide resin composition and blended with a drum blender. Metal powder with inorganic reinforcement This is preferable because it can suppress damage and can obtain a good metallic tone. When a polyamide resin mixture is used as a raw material polyamide resin, it is blended in advance using a drum blender, and the polyamide resin mixture is used. The cylinder set temperature of the twin screw extruder was 290 ° C., and the polymer was charged from the hopper. (B) The inorganic reinforcing material is preferably added by side feed. It is preferable that the polymer charging portion and the inorganic reinforcing material charging portion are sufficiently purged with N ₂ .

The chair parts and chair legs of the present invention are hollow injection molding methods, two-color molding methods, sandwich molding methods, injection compression molding methods, as well as normal chair parts, injection molding methods used for molding chair legs, Further, a molding method or the like provided with a discarded cavity can be applied, and is not limited at all.
The molded article molded with the polyamide resin composition of the present invention is excellent in metallic appearance, gloss, and mechanical properties, and is suitable for thick-walled chair parts. Among these parts, office chairs Particularly suitable for legs.

Hereinafter, the present invention will be described in more detail with reference to examples.
(A) Polyamide resin (a1) Polyamide 6 / Polyamide 66 = 9/1 (weight ratio) copolymer: Formic acid solution viscosity 35. 90 wt% of equimolar salt of adipic acid and hexamethylenediamine and 10 wt% of ε-caprolactam were obtained by ordinary melt polymerization.
(A2) Polyamide 6: Injection molding grade Ube Industries, Ltd. (a3) Polyamide 66: Trade name Leona 1300, Asahi Kasei Corporation (b) Glass fiber, Asahi Fiber Glass Co., Ltd. Trade name CS0 3JA416
(C) Metal powder manufactured by Toyo Aluminum Co., Ltd.

<Manufacturing method of polyamide resin composition>
(A1), (a2), and (a3) were blended at a composition ratio in the table using a drum blender to obtain a polyamide resin composition. Next, these resins and (b) glass fibers were melt-kneaded under the following conditions using a twin-screw extruder (PCM45 manufactured by Ikekai Tekko Co., Ltd.).
The cylinder set temperature of the twin screw extruder was 290 ° C., the screw rotation speed was 150 rpm, and the polymer was charged from the hopper. (B) The glass fiber was added by side feed so that the glass fiber content of the resin composition was 15 to 65 wt% from C5 (Zone 5). The polymer charging part and the glass fiber charging part were sufficiently purged with N ₂ . A vent vacuum was performed from C7 (Zone 7) (300 mmHg). In this way, (A) reinforced polyamide resin composition to which an inorganic reinforcing material was added was obtained.
Further, 20% by weight of (c) metal powder was blended with the polyamide resin and melt-kneaded with an extruder to obtain (B) a master batch.
The molding material was obtained by blending the (A) reinforced polyamide resin composition and the (B) masterbatch using a drum blender so that the metal powder had the composition shown in the table.

Moreover, Tc measurement and evaluation in Examples and Comparative Examples were performed by the following methods.
(1) Measurement of crystallization temperature (Tc) The temperature (Tc) at the time of crystallization from a molten state was obtained by adding a reinforcing polyamide resin composition obtained by adding an inorganic reinforcing material from an extruder to a differential scanning calorimeter. Using (DSC) (manufactured by Pyris 1 PERKIN ELMER), the temperature was raised to 300 ° C. at 20 ° C./min, held for 3 minutes, and then the peak temperature when the temperature was lowered to 100 ° C. was crystallized temperature (Tc) It was.

(2) Molded product surface appearance Using an FE-120 injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd.), the mold surface temperature is 80 ° C., the resin temperature is 280 ° C., the holding pressure is 400 kgf / cm ² , and the screw advance speed is 100 mm / Second, using a flat plate 120 mm long x 80 mm wide x 10 mm thick formed by a side gate with a gate size of height 3 x width 6 mm, the surface area φ45 mm of the flat plate is a 60 ° specular gloss measurement method specified in JIS K8741 It was measured with a digital variable gloss meter: manufactured by Suga Test Instruments Co., Ltd.
Judgment of the metallic tone was performed visually, and evaluation was performed in two stages: ◯: good metallic tone, ×: low surface gloss or metallic tone but not good (insufficient glare feeling, excessive glare feeling).

(3) Tensile strength Using a PS-40E5A injection molding machine (manufactured by Nissei Plastic Industry Co., Ltd.), mold surface temperature 80 ° C., resin temperature 280 ° C., holding pressure 400 gf / cm ² , screw advance speed 100 mm / sec. After forming the test piece 1A type defined in ISO-527, immediately after molding, the dumbbell piece was put in an aluminum bag and sealed by heat sealing. Evaluation was carried out at a pulling speed of 5 mm / min. Moreover, the glossiness and the tensile strength showed the average value measured 5 times each.

(4) Cooling time (1) Molding was performed with the same molding machine, mold, and molding conditions as the molded product surface appearance. The injection time during the molding cycle was 20 seconds, and the cooling time was changed to obtain the shortest cooling time for obtaining a normal molded product. A normal molded product refers to a molded product in which the protruding pin bites into the molded product at the time of mold release and does not break through.

[Examples 1-4, Comparative Examples 1-2]
Table 1 shows the influence of the composition constituting the polyamide matrix. Table 1 shows the results of evaluation using molded products obtained with the composition ratios shown in Table 1.
In order to compare the appearance and cooling time, the blending amount and shape of (b) glass fiber, (c) aluminum flakes are constant, (a1) copolymer, (a2) polyamide 6, (a3) composition ratio of polyamide 66 Changed. In addition to the good appearance of Examples 1 to 4, the cooling time was 30 seconds or longer in Comparative Example 1, although the appearance was good in Comparative Example 1 compared to the cooling time of less than 30 seconds. In Comparative Example 2, the gloss was low.

[Examples 5-6, Comparative Examples 3-4]
Table 2 shows the effect of the glass fiber content. Table 2 shows the results of evaluation using molded products obtained at the composition ratios shown in Table 2.
In order to compare the appearance and tensile strength, the composition ratio of (a1) copolymer, (a2) polyamide 6, (a3) polyamide 66, (c) the blending amount and shape of aluminum flakes are constant, and (b) glass The amount of fiber was changed. In addition to the good appearance of Examples 5 to 6, the tensile strength was less than 100 MPa compared to Comparative Example 3, although the appearance of Comparative Example 3 was good because there were few glass fibers. Moreover, since the comparative example 4 had many glass fibers, the gloss was low.

[Examples 7-8, Comparative Examples 5-7]
Table 3 shows the influence of the amount of aluminum flakes. Table 3 shows the results of evaluation using molded products obtained at the composition ratios shown in Table 3.
In order to compare the appearance and the tensile strength, the composition ratio of (a1) copolymer, (a2) polyamide 6, (a3) polyamide 66, (b) compounding amount of glass fiber, (c) particle size of aluminum flakes (C) The amount of aluminum flake blended was changed. Compared with Examples 7 to 8 having a good appearance, Comparative Examples 5 to 6 were not good metallic tones because the amount of aluminum flakes contained was small or large.
Further, when Example 1 in which the blending amount of aluminum flakes was 1% by weight and Comparative Example 7 were compared, even if aluminum flakes were blended in 1% by weight, there was almost no decrease in tensile strength.

[Examples 9 to 10, Comparative Examples 8 to 9]
Table 4 shows the effect of aluminum flake particle size. Table 4 shows the results of evaluation using molded products obtained with the composition ratios shown in Table 4.
In order to compare the appearance, the composition ratio of (a1) copolymer, (a2) polyamide 6, (a3) polyamide 66, (b) glass fiber content, (c) aluminum flake content is constant, c) The particle size of the aluminum flakes was changed. Compared with Examples 9-10 having a good appearance, Comparative Examples 8-9 were not good metallic tones because the particle size of the aluminum flakes was small or large.

[Example 11]
Using a resin composition shown in Table 5, five chair legs (maximum thickness 50 mm, height 120 mm, maximum diameter 650 mm, gate size: disk gate thickness 3 mm) using a 1000 t injection molding machine, mold temperature 80 ° C. setting a resin temperature of 280 ° C., injection pressure 800 kgf / cm ^2, holding pressure 400 kgf / cm ^2, it was molded at a screw forward speed 100 mm / sec.
The molded product obtained here was subjected to a compression test at a compression speed of 5 mm / min using a universal testing machine (manufactured by Instron). The compressive strength at which breakage occurred at this time was 25 kN. The compressive strength showed the average value measured 3 times. The evaluation results are shown in Table 5.
As is clear from this result, it can be seen that the legs of the chair injection-molded with the resin composition of the present invention have a strength that can withstand practical use.

  Chair parts molded with the metallic polyamide resin composition for chair parts of the present invention, among them, particularly thick parts, specifically, office chair legs, have excellent metallic appearance, gloss, and mechanical properties. It is suitable for office and residential parts.

Claims (4)

(A) One or more polyamide resins 32 to 84 selected from polyamide 6, polyamide 66, and polyamide 6 / polyamide 66 copolymer having a temperature (Tc) of crystallization from a molten state of 180 to 210 ° C. 8 wt%, (b) an inorganic reinforcing material 15 to 65 wt%, in that it consists Rume Tarik tone polyamide resin composition to contain metal powder 0.2-3% by weight of the average particle diameter 10~90μm (c) A chair part having a thick part of 5 mm or more, which is characterized . (C) a metal powder having an average particle diameter of 10~90μm is, the chair portion article according to claim 1, characterized in that the flaky aluminum powder. (A) The temperature (Tc) for crystallization from the molten state of the polyamide resin is 180 to 195 ° C.
Seat part article according to claim 1 or 2, characterized in that. The chair part according to any one of claims 1 to 3 , wherein the chair part is a chair leg.