JPH0242385B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a resin composition suitable for use in acoustic equipment. [Prior art and its problems] In recent years, audio equipment such as speaker boxes,
Player housings, boom box housings, etc. are made of plastic. This kind of audio equipment is
In order to have good acoustic properties, it is required that the internal loss (tan δ), elastic modulus, and specific gravity be large. However, when a filler such as a metal is added to a thermoplastic resin in a large amount, particularly in excess of 50% by weight, in order to increase the specific gravity as part of improving acoustic properties, the following drawbacks occur. That is, during molding, the kneading machine, molding machine, etc. using metal powder are significantly worn and damaged. Metal powder aggregates and adheres inside the kneading machine and molding machine, and is sintered and solidified, resulting in extremely poor productivity of pellets and molded products. The mechanical strength of the molded product is insufficient. During continuous production of molded products, weight differences between molded products,
The density difference is large, causing variations in dimensional stability. Moreover, especially when the amount of metal powder blended exceeds 70% by weight, the drawbacks mentioned above become noticeable and the moldability deteriorates, making it necessary to increase the gate diameter and use a direct gate during injection molding. Since it is difficult to mold, it is limited to molded products such as small parts, although it is insufficient, and it is unsuitable for molding into large molded products such as large speaker boxes. In order to avoid such drawbacks, the amount of metal powder blended may be lower than 50% by weight.
It is true that it has good moldability and can be molded into both small and large molded products, but the high specific gravity required for audio equipment,
Large mechanical strength, large internal loss, etc. cannot be obtained. This invention has been made based on the above circumstances. That is, the purpose of the present invention is to solve the above-mentioned problems, and to provide pellets with excellent moldability and mechanical strength even though they contain 50% by weight or more of metal powder, etc., as well as high pellet moldability and productivity. Another object of the present invention is to provide a resin composition that does not cause damage or wear to kneading machines, molding machines, etc. during molding, and can be suitably molded into acoustic equipment with good acoustic properties. [Means for Solving the Problems] This invention for solving the problems described above uses 50 to 5 parts by weight of polyamide resin and 50 to 5 parts by weight of zinc powder and/or metal powder or metal oxide powder whose surface is coated with zinc. ~95 parts by weight for a total of 100 parts by weight,
A resin composition for audio equipment, comprising 1 to 10 parts by weight of potassium titanate fiber, 1 to 10 parts by weight of modified polyolefin, and 0.1 to 1.0 parts by weight of a lubricant, and having a density of 2.27 to 4.75 g/ml. Yes, this resin composition for audio equipment has internal loss, elastic modulus,
Since it can be processed into molded products with high specific gravity, it is suitable for audio equipment with excellent acoustic properties.In addition, it has excellent properties such as not causing significant damage and wear to kneading machines, molding machines, etc. during kneading and molding. have a property. The polyamide resin is not particularly limited, and various resins can be used. Broadly divided, (1) those obtained by ring-opening polymerization of aliphatic lactams, (2) those obtained by polycondensation of aliphatic diamines and aliphatic dicarboxylic acids or aromatic dicarboxylic acids, and (3) condensation polymerization of amino acids. and copolymers obtained by polymerizing various nylon monomers. By such a synthesis method, - is added to the polymer chain.
Various polyamides are produced by generating CONH- groups. As belonging to (1) above, Nylon 6 (from ε-caprolactam), Nylon 12 (from lauryllactam) Items belonging to (2) above include nylon 66 [hexamethylene diamine (HMD)]
and adipic acid] Nylon 610 (HMD and sebacic acid) Nylon 612 (HMD and dodecadionic acid) MXD, Nylon 6 [meta-xylene diamine (MXD) and adipic acid] H ₂ N (CH ₂ ) _o NH ₂ +HOOC (CH ₂ ) _n-2 COOH→ −NH(CH ₂ ) _o NHCO(CH ₂ ) _n-2 CO−+H ₂ O Among those belonging to (3) above, nylon 11 H ₂ N−(CH ₂ ) ₁₀ −COOH→NH( CH ₂ ) ₁₀ CO−+
There are H ₂ O, etc. Among these, especially nylon 6,
Preferably, nylon 66 is used. Next, in this invention, the second component is the subsalt powder and/or the metal powder or metal oxide powder whose surface is coated with zinc. Here, examples of the metal powder or metal compound powder whose surface is coated with zinc include powders of iron, iron oxide, copper, lead oxide, and the like. There are no particular restrictions on the method of coating the surface of such metal powder or metal compound powder with zinc; for example, (1)
Examples include a method in which molten zinc is sprayed onto metal powder or metal compound powder, and (2) a method in which metal powder or metal compound powder is poured into molten zinc and stirred. The thickness of the zinc coating the surface is 0.5
A range of ~3μ is preferred. Further, the particle size of the powder is usually 1 to 15μ, preferably 4 to 6μ. The blending ratio of the polyamide resin (first component) and zinc powder and/or metal powder or metal oxide powder whose surface is coated with zinc (second component) is such that the first component is 50 to 5 parts by weight, preferably is 40
~10 parts by weight, and the second component is 50 to 95 parts by weight, preferably 60 to 90 parts by weight. If the blending ratio of the first component exceeds 50 parts by weight, the molded product will have poor mechanical strength and will also have a low specific gravity, which is not preferred. On the other hand, if the blending ratio of the first component is less than 5 parts by weight, the kneading machine, molding machine, etc. may suffer wear damage, adhesion, sintering, and solidification may easily occur inside the machine, and the appearance of the molded product may increase. This is not desirable because it causes roughness. Furthermore, in this invention, potassium titanate fibers are used as the third component. Here, the potassium titanate fiber has the general formula K ₂ O・n (TiO ₂ ) or K ₂ O・n (TiO ₂ )・1/2H ₂ O (in the formula, n is an integer from 2 to 8). ) Single crystal fibers of potassium titanate are mentioned. Specifically, for example, potassium titanate fiber (trade name: TISMO, average fiber diameter 0.2 to 0.5 μm, average fiber length 10 to 20 μm, aspect ratio 20 to 100) manufactured by Otsuka Chemical Co., Ltd. is preferable, and this can be used as is. can be used. Further, as the potassium titanate fiber, one which has been surface-treated with a silane coupling agent such as aminosilane or a titanate coupling agent such as isopropyl tristearoyl titanate can also be used. By using such surface-treated potassium titanate fibers, the abrasion resistance of the resin composition can be improved compared to a resin composition using untreated potassium titanate fibers, and it is also possible to improve mechanical resistance. The strength of the target can also be improved. Here, the abrasion resistance of the resin composition refers to the property that the kneading machine, etc. and the molded product are less likely to be worn out or damaged. Here, the third component is 1 to 10 parts by weight based on a total of 100 parts by weight of the first component and the second component,
It is preferably blended in an amount of 2 to 8 parts by weight. If the blending ratio of the third component is less than the lower limit of the blending ratio, the coefficient of friction will increase, the kneading machine etc. will be likely to be worn and damaged during molding, and the mechanical strength of the molded product may not be sufficient. On the other hand, if the blending ratio of the third component exceeds the range of the above-mentioned blending ratio, the kneading function is likely to be worn and damaged during molding, and the appearance of the molded product will be rough, which is not preferable. Next, in this invention, a modified polyolefin is used as the fourth component. The modified polyolefin may be a polyolefin modified with an unsaturated carboxylic acid (including its anhydride) or a derivative thereof, or a polyolefin modified with a liquid rubber and an unsaturated carboxylic acid (including its anhydride) or a derivative thereof. It is possible to suitably use those that have been modified. Here, terminal hydroxylated polybutadiene is suitable as the liquid rubber. In producing this modified polyolefin, a polyolefin such as polypropylene, a liquid rubber, and an unsaturated carboxylic acid or its derivative are mixed in a solvent such as xylene, toluene, heptane, or monochlorobenzene using a radical generator such as benzoyl peroxide. All you have to do is react. For details on the manufacturing method of this modified polyolefin, please refer to JP-A-54-
Since it is disclosed in Publication No. 124049, detailed explanation thereof will be omitted. In this invention, when the modified polyolefin is used, it is possible to improve the miscibility between the polyamide resin and zinc powder, and further,
It is possible to increase the impact strength of the molded product obtained. Here, the fourth component, that is, the modified polyolefin is the sum of the first component and the second component.
It is blended in an amount of 1 to 10 parts by weight, preferably 2 to 8 parts by weight, per 100 parts by weight. If the blending ratio of this modified polyolefin is less than the above range, the mechanical strength of the molded article will decrease. Furthermore, if the blending ratio of the fourth component exceeds the above range, the difference in weight and density of the molded product will increase, and the appearance of the molded product will become rough, which is not preferable. In this invention, a lubricant is used as the fifth component. Examples of lubricants include hydrocarbon lubricants such as liquid paraffin, natural paraffin, and wax; fatty acid lubricants such as higher fatty acids and oxyfatty acids; alcohol lubricants such as lower alcohols of fatty acids and polyglycols; calcium stearate,
Examples include metal soaps such as barium stearate; silicones such as silicone oil and modified silicone; and the like. Among these, aliphatic lubricants, alcohol lubricants, silicones, etc. are particularly suitable. Here, the fifth component is 0.1 to 10 parts by weight, preferably 0.3 to 8 parts by weight, based on the total amount of the first component and the second component.
Blend in parts by weight. If the blending ratio of this fifth component is below the above range, the coefficient of friction will increase, making molding difficult, and moreover, it will easily adhere to the inside of a kneader, sinter, and solidify, and the weight difference of molded products will increase. This is not preferable because the density difference becomes large. On the other hand, if the blending ratio of the fifth component exceeds the above range, slips are likely to occur during molding, and the lubricant will separate the first component and the second component, resulting in the inside of the kneading machine etc. This is not preferable because it tends to adhere, sinter, and solidify, and it bleeds out onto the surface of the molded product. Further, in the present invention, carbon black may be blended as the sixth component. As this carbon black, carbon blacks of various grades manufactured by various methods can be used, for example, those manufactured by a furnace method, a channel method, a thermal method, etc. can be used. Further, furnaces for rubber, pyrolytic carbon, carbon for batteries, carbon for black colors, etc. can be used, and there is no particular restriction on the particle shape of carbon black, and carbon fiber can also be used. Examples of this carbon fiber include pan-based carbon fiber,
Examples include pitch carbon fiber. In order to reduce the surface resistivity and/or volume resistivity of molded acoustic equipment, it is preferable to use conductive carbon black as the carbon black. This type of carbon black is Ketsuen Black manufactured by Lion Akzo [EC DJ-600, specific surface area 1300 m ² /g, BET method]
can be easily obtained commercially. The blending amount of this black carbon is the same as that of the first component and the second component.
1 to 20 parts by weight per 100 parts by weight of the ingredients,
Preferably it is 1 to 10 parts by weight. If the blending amount of carbon black is less than the above range, not only will the blending effect be lost, but the friction coefficient of the resin composition will increase, making it difficult to mold, and may cause adhesion, sintering, solidification, etc. inside the kneading machine, etc. This is undesirable because it increases the difference in weight and density of the molded product, which is an audio equipment.If it exceeds the above range, the dispersibility of carbon black becomes poor and the appearance of the molded product may be poor. The resin composition for audio equipment according to the present invention can be obtained by blending the first to fifth components, and if necessary, the sixth component as raw materials. Antistatic agents, colorants,
Various additives such as flame retardants, antioxidants, ultraviolet absorbers, plasticizers, inorganic fillers, and heat stabilizers can be added and blended. Various surfactants can be used as the antistatic agent. Further, examples of the coloring agent include poorly soluble azo dyes, red coloring agents, cadmium yellow, cream yellow, titanium white, and the like. Examples of the flame retardant include inorganic antimony oxide, zirconium oxide, etc., and organic phosphoric acid ester, tricresyl phosphate, etc. As the antioxidant, triazole-based, salicylic acid-based, and acrylonitrile-based antioxidants are used. Further, examples of the plasticizer include phthalic acid diester, butanol diester, phosphoric acid diester, and the like. Examples of the inorganic filler include calcium carbonate, gypsum, talc, mica, barium sulfate, glass fiber, wollastonite, magnesium hydroxide, aluminum hydroxide, and the like. The resin composition for audio equipment according to the present invention includes the polyamide resin, zinc powder and/or metal powder or metal oxide powder whose surface is coated with zinc, potassium titanate fiber, modified polyolefin, lubricant, and carbon black. Then, it can be manufactured by blending the various additives mentioned above. The blending method is not particularly limited, and examples include a method of premixing all the components and kneading the obtained premix, a method of mixing and kneading all the components at once, and the like. The mixing or kneading may be carried out using, for example, a ribbon blender, tumble mixer, Henschel mixer,
This can be carried out using an open roll, a Banbury mixer, a single-screw extruder, a twin-screw extruder, a single-screw reciprocating screw kneader, or the like. More specifically, preferred mixing and kneading procedures are as follows. That is, a mixture obtained by blending the raw material components of the present invention using, for example, a Henschel mixer is first kneaded for 5 to 20 minutes with a high-speed mixer at a temperature of 100 to 250°C. The rotation speed of the high-speed mixer at this time is 400 to 1000 r.pm, preferably 400 r.pm.
~900r.pm. If the rotation speed is less than 400 r.pm, kneading may be insufficient, and if the rotation speed exceeds 1000 r.pm, the raw material temperature may rise abnormally, causing deterioration of the raw material components. After the kneading, the mixture is further kneaded using a low speed mixer at a temperature of 80 to 110°C. In this kneading process,
Since the kneading proceeds at a relatively low temperature, the kneaded material is gradually cooled and becomes fine lumps. here,
The rotational speed of the low-speed mixer is not particularly limited, but is usually 100 to 200 rpm. The kneaded product obtained through such a two-stage kneading process is kneaded and extruded using a single screw extruder, usually at 190 to 250°C. In this step, it is important not only to perform a simple extrusion operation but also to perform sufficient kneading together with extrusion. In this way, kneading is carried out thoroughly in three stages, but because the proportion of metal components in the compound that can be kneaded is large, the kneading machine or extruder used for kneading is different from that for ordinary resin compositions. Although it may be used for plastics, it is more preferably used in the ceramic industry. The resin composition for audio equipment obtained in this way can be molded into audio equipment such as speaker boxes, player housings, radio cassette housings, microphone housings, and cassette tapes by various molding methods such as injection molding, mold molding, and extrusion molding. It is molded into cases, housings for electronic organs and pianos, hand speakers, etc. [Effects of the Invention] According to the present invention, the following effects can be achieved. (1) This resin composition for audio equipment contains zinc powder and/or metal powder or metal oxide whose surface is coated with zinc at a ratio of 50 to 95 parts by weight based on the total amount of polyamide resin. Therefore, it has a high specific gravity and can be molded into acoustic equipment that does not easily cause vibrations due to sound waves. (2) The molded product of this resin composition, which is made by blending specific amounts of the first to fifth components, has high internal loss and specific gravity, good dimensional stability, high mechanical strength, and is resistant to temperature differences. Therefore, the resin composition can be made into a molded article that does not easily deform, so this resin composition is suitable for use in audio equipment that is strong and durable and has good acoustic properties. (3) A molded article specifically containing conductive carbon black as the sixth component reduces surface resistivity and volume resistivity, and is therefore suitable as a housing surrounding areas where electronic and electrical components are concentrated. (4) Since the above-mentioned first to fifth components are blended, there is less wear and damage to the kneading machine, molding machine, etc. due to metal powder during molding. Powder does not adhere, sinter, or solidify, and pellet formability is improved.
High productivity. Therefore, it can be freely molded into anything from small to large-sized audio equipment. [Example] Next, Examples and Comparative Examples of the present invention will be shown. (Production example of modified polyolefin) Polypropylene [Melt Index (MI)
8g/10 minutes, density 0.91g/ ^cm3 , product name: J700G,
manufactured by Idemitsu Petrochemical Co., Ltd.] and 100 parts by weight of terminally hydroxylated 1,4-polybutadiene (number average molecular weight
3000, Product name: Poly bd R45HT, ARCO
Chem.Div.) 5 parts by weight, 20 parts by weight of maleic anhydride, 1.72 parts by weight of dicumyl peroxide,
Mix with 600 parts by weight of xylene and heat to 120℃ while stirring.
The mixture was heated at 140° C. for 1 hour and then heated at 140° C. for 3 hours to carry out the reaction. After the reaction was completed, unreacted butadiene, maleic anhydride, and the solvent xylene were removed according to a conventional method to obtain modified polybutadiene. Examples 1 to 29, Comparative Examples 1 to 15 The formulations shown in Table 1 were fed into a high-speed mixer heated to 180°C and stirred and mixed at 600 rpm for 15 minutes. The mixture was heated to 200° C. to gel and thoroughly kneaded. After this kneading, mix the mixture in a low speed mixer at 20℃.
Cool to 110℃ and heat at 150r.pm until fine lumps form.
It was stirred with Next, the obtained kneaded product was extruded at a resin temperature of 240°C using a single screw extruder (vented extruder with a diameter of 50 mm, manufactured by Nakatani Kikai, NVC-59).
Pellets of 3φ×5mm were produced. The flexural modulus and density of Tesna pieces obtained by molding these pellets were evaluated as follows. The results are shown in Table 1. [Bending elastic modulus (Kg/cm)] Based on ASTM S-638. [Density (g/ml)] Based on the underwater substitution method. In addition, using pellets having the composition shown in Table 1, injection molding machines [manufactured by Sumitomo Heavy Industries, Ltd., Neomat]
N515/150B] at 250 to 280℃ to form a speaker box (90 x 80 x 150 mm, wall thickness 4 mm, gate 1 mm φ, a hole for mounting a 70 mm φ speaker unit in the center of the front of the box). The acoustic characteristics were measured and evaluated. [Acoustic characteristics] The internal loss (tan
δ) value was measured (the larger the tan δ value, the better the acoustic properties.). Also, this
The reciprocal of the tan δ value was taken as the resonance sharpness. The specifications of each raw material used in this example and comparative example are shown below. [Polyamide] For Examples 1 to 14, Examples 16 to 23, Examples 26 to 29, and Comparative Examples 1 to 15, nylon 6 (manufactured by Kanebuchi Kagaku Kogyo, trade name: LM-102) (in Table 1) was used. Nylon 610 (represented by B in Table 1) for Examples 15, 24, and 25. [Metal powder] For Examples 1 to 15, Examples 21 to 24, Comparative Examples 1 to 10, and Comparative Examples 13 to 15, zinc (manufactured by Sakai Chemical Co., Ltd.,
Specific gravity 7.1, particle size 4-5μ) (Hereinafter, all zinc powders are made by Sakai Chemical and have a specific gravity of 7.1.), Example 16 is zinc powder with a particle size of 1-3μ, and Example 17 is a particle size 10-15μ. Zinc powder, Examples 18 and 25 are iron powder whose surface is coated with zinc (manufactured by Dowa Iron Powder, particle size 5-7μ, specific gravity
7.2), Example 19 is an iron oxide powder whose surface is coated with zinc (manufactured by Dowa Iron Powder, particle size 6-10μ, specific gravity 7.1), and Example 20 is a copper powder whose surface is coated with zinc (manufactured by Dowa Iron Powder). , particle size 6-10μ, specific gravity 7.4), Example 26 is iron powder (manufactured by Dowa Iron Powder, particle size 10-15μ, specific gravity 7.8), Example 27
Example 28 is copper powder (manufactured by Dowa Iron Powder, particle size 5 to 7μ, specific gravity 8.9), and Example 28 is lead oxide powder (manufactured by Dowa Iron Powder, particle size 15 to 20μ,
Specific gravity 9.4), Example 29 is zinc powder (manufactured by Sakai Chemical Co., Ltd., particle size
20 to 30μ, specific gravity 7.1) were used, respectively. [Potassium titanate fiber (displayed as potassium titanate in the table for convenience of tabulation)] Manufactured by Otsuka Chemicals, average particle size 0.1-0.5μ, average fiber length 10-2μ, aspect ratio 20-100, Product name:
I used TISMO. [Modified polyolefin] The one obtained in the above production example was used. [Lubricant] Examples 1 to 19, Comparative Examples 1 to 15, and Examples 26 to
For 29, stearic acid, for Example 20, stearyl alcohol, for Example 21, silicone (Shin-Etsu Silicon, KF-96), for Example 22, magnesium stearate, for Examples 23 and 24, benzene sulfon. Butylamide (manufactured by Daihachi Kagaku, BM-4) and Example 25 (magnesium stearate) were used, respectively. As shown in Table 1, the molded product obtained by molding the resin composition according to the present invention has a high specific gravity, a high flexural modulus, and a large internal loss, so it can be used as an acoustic material with good acoustic properties. It is suitable for molding, and will not clog the nozzle with metal powder and make molding impossible, and will not cause lubricant to bleed out on the surface of the molded product and air bubbles will occur inside the molded product. The surface of the molded product was beautiful.

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Claims (1)

[Claims] 1. 1 to 10 parts by weight of potassium titanate fiber per 100 parts by weight of 50 to 5 parts by weight of polyamide resin and 50 to 95 parts by weight of zinc powder and/or 50 to 95 parts by weight of metal powder or metal oxide powder whose surface is coated with zinc. ,
1 to 10 parts by weight of modified polyolefin and 0.1 part of lubricant
Contains ~1.0 part by weight and has a density of 2.27~4.75g/
A resin composition for audio equipment, characterized in that ml.