JPH03223355A - Resin composition - Google Patents

Abstract

PURPOSE:To prepare a resin compsn. which gives a molded article having a high elastic modulus, high internal loss, and excellent appearance with little sink mark by compounding a crystalline aliph. polyolefin resin, a specific aliph. polyolefin resin, and a specific inorg. filler. CONSTITUTION:A resin compsn. is prepd. by compounding a crystalline aliph. polyolefin resin (e.g. a polypropylene), an aliph. polyolefin resin having a glass transition point of -50 deg.C to +25 deg.C and obtd. by the copolymn. with an alkyl (meth)acrylate, and an inorg. filler selected from the group consisting of wollastonite and hollow spherical inorg. materials (e.g. a silica-alumina ceramic or a glass balloon) in an amt. of 30-80wt.% based on the compsn. The compsn. gives a molded article having a high elastic modulus, high internal loss, and excellent appearance with little sink mark, and is suitably used for applications such as a base plate of a driving part or an acoustic vibrating plate in a speaker box, record player, cabinet, and motor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin composition that can be particularly suitably used as a substitute for wood, pulp paper, etc. in applications where they are used to take advantage of their functional characteristics. .

[Conventional technology] In applications where wood, pulp paper, etc. have traditionally been used, problems include, for example, low degree of freedom in design, long time required for molding and assembly, and large changes in physical properties in dry and wet conditions. In order to improve the problems of wood, pulp paper, etc., which have A crystalline polyolefin resin composition has been reported as a material with both
(See Publication No. 945).

[Problems to be Solved by the Invention] However, since the resin of the crystalline polyolefin resin composition is crystalline, the volume shrinkage of the molded product is large when the molded product is molded. There are drawbacks that impair the

Therefore, an object of the present invention is to provide a resin composition that has a high modulus of elasticity and a high internal loss, has excellent processability, and is capable of producing a molded product with small whiskers and a beautiful appearance.

[Means for Solving the Problems] According to the present invention, the above object is achieved by using (A) a crystalline aliphatic polyolefin resin and (B) a glass transition temperature (hereinafter abbreviated as Tg) of -50. An aliphatic polyolefin resin copolymerized with an acrylic acid alkyl ester or a methacrylic acid alkyl ester within the range of ~+25°C, and (C) at least one inorganic filler selected from wollastonite and hollow spherical inorganic substances. Become,
This is achieved by providing a resin composition characterized by having an inorganic filler content of 30 to 80% by weight.

Further, a resin composition comprising the above-mentioned components (A), (B), and (C) and (D) mica, and the content of the inorganic filler including mica is 30 to 80% by weight. This is achieved by providing

As the crystalline aliphatic polyolefin resin in the present invention, polyethylene, polypropylene, polybutene, poly3
-Methyl-pentene-1, poly4methyl-pentene-1
Among them, polypropylene, polyethylene, and ethylene copolymer polypropylene are preferable because they have good moldability and are inexpensive. Further, as the crystalline aliphatic polyolefin resin, a resin copolymerized with a compound having a polar group, such as maleic anhydride, acrylic acid, glinnor methacrylate, or a silane compound having an ethylenically unsaturated bond, can also be used. These crystalline aliphatic polyolefin resins provided with polar groups are extremely effective in improving the mechanical performance of the resulting molded articles. The amount of the compound imparting a polar group is used within a range that does not inhibit the crystallinity of the aliphatic polyolefin resin. Moreover, these copolymers may be not only random copolymers but also block or graft copolymers.

The blending ratio of the crystalline aliphatic polyolefin resin is preferably 50 to 95% by weight, more preferably 55 to 95% by weight of the total resin amount. If the blending ratio is less than 50% by weight, the elastic modulus and heat resistance of the molded product obtained from the composition will decrease, and if it exceeds 95% by weight, the internal loss of the molded product obtained from the composition will be insufficient. I don't like either of them because of that.

In the present invention, an aliphatic polyolefin (hereinafter referred to as
Polyolefin copolymers (sometimes abbreviated as polyolefin copolymers) include ethylene-methyl acrylate, ethylene-ethyl acrylate, ethylene-isopropyl acrylate, ethylene-n-propyl acrylate, ethylene-n-butyl acrylate, and ethylene-methyl acrylate. - n-hexyl methacrylate,
Examples include ethylene-n-octyne methacrylate. Preferably used is an ethylene-ethyl acrylate copolymer, which has a remarkable effect of improving internal loss in the room temperature region when combined with a crystalline aliphatic polyolefin resin. Here, Tg refers to a dynamic viscoelasticity measuring device (Pybron DDV-I [IEA).

(manufactured by Toyo Holdwin) to measure the temperature dependence of internal loss at a frequency of 110H2, and refers to the temperature at which the internal loss becomes maximum.

The copolymerization rate of acrylic acid alkyl ester or methacrylic acid alkyl ester (hereinafter simply referred to as acrylic acid copolymerization rate) is preferably in the range of 15 to 50% by weight. When a copolymer with an acrylic acid copolymerization rate of less than 15% by weight is used, the internal loss improvement effect of the molded article obtained from the composition is unsatisfactory; If a copolymer exceeding the above amount is used, the miscibility of other components with the aliphatic polyolefin resin will be poor, and the heat resistance of the molded article obtained from the composition will be deteriorated, which is not preferable. The blending ratio of the polyolefin copolymer is preferably 5 to 50% by weight based on the total resin amount, and 1
More preferably, it is 0 to 45% by weight. If the copolymer content is less than 5% by weight, the internal loss improvement effect of the molded product obtained from the composition will be unsatisfactory, while if it exceeds 50% by weight, the molded product obtained from the composition will be unsatisfactory. Both are unfavorable because the elastic modulus and heat resistance are unsatisfactory.

The wollastonite in the present invention has an average diameter of 1 to 5
The average length is preferably in the range of 2 to 500 μ, the average diameter is in the range of 2 to 30 μ, and the average length is more preferably in the range of 3 to 400 μ. The diameter and length of wollastonite are determined by using an electron microscope or an optical microscope, taking a photograph of wollastonite at a magnification that makes the diameter 1 mm or more, and measuring the diameter and length of 200 or more wollastonites. This is the average value.

The hollow spherical inorganic substance in the present invention has a density of 0.5 to 2.
．． 4g/am3 range, average particle size 2-100μ
It is preferable that it is in the range of . The average particle diameter of the hollow spherical inorganic material was determined by the same method as the method for determining the average particle diameter of mica, which will be described below. Examples of such hollow spherical inorganic materials include silica-alumina ceramics, glass balloons, and Noras balloons.

In the present invention, the blending ratio of the inorganic filler is 30 to 80% by weight, preferably in the range of 40 to 80% by weight, based on the total composition amount. If the blending ratio is less than 30% by weight, the sink mark effect of the molded article obtained from the composition will not be improved, and if the blending ratio exceeds 80% by weight, it will be difficult to knead the composition. In the present invention, in order to further increase the elastic modulus and internal loss of the molded article obtained from the composition, mica can be blended into the resin composition consisting of the above-mentioned components. In this case, the blending ratio of the inorganic filler containing mica is 30 to 80% by weight, preferably 40 to 80% by weight, based on the total amount of the composition.

Examples of mica in the present invention include white mica, gold mica,
Examples include synthetic mica, with a weight average aspect ratio of 1.
Mica of 0 or more is preferred. If the weight average aspect ratio of mica is less than 10, the elastic modulus and internal loss of the molded article obtained from the composition will be low, which is not preferable. The weight average flake diameter of mica is not particularly limited, but is preferably 10 μm or more.

The weight average aspect ratio of mica is a value determined using equation (1) from the weight average flake diameter a and the weight average flake thickness d measured by the following method.

Weighted average aspect ratio = f! /d (1)
Here, the weight average flake diameter σ of mica is 50% by weight of the mica subjected to wet classification using standard sieves with various openings and plotting the results on a Rosin-Ra+nm1ar diagram. This is the value calculated from the opening C3° of the sieve through which the sieve passes, and from that value using equation (2).

ρ-7・1]5o(2) In addition, the weight average flake diameter Q of the above hollow spherical inorganic substance
is the value calculated using equation (3).

C-J. (3) Also, the weight average flake thickness d of mica is C,
E, single-particle membrane properties on the water surface as reported by Capes et al. (C.

E. Capes and R.C. Coleman.
Ind, Eng, ChemFundam, 1
This is a value calculated from equation (4) using the occupied area S of the flakes on the water surface measured by 2.124 (1973)).

d = (4)ρ(
1-ε)S Here, W is the weight of the flakes used for measurement, S is the area occupied by the flakes on the water surface, ρ is the specific gravity of the flakes, (1-ε
) is the occupancy rate when the flakes are in a close-packed state on the water surface, and when the flakes are mica, the value of ρ is 2.86 g/ca + 3, and the value of (1-ε) is 0.9 or used in calculations.

The blending ratio of mica is 50% by weight or less of the total composition, preferably in the range of 3 to 40% by weight. When the blending ratio exceeds 50% by weight, the mica used in the present invention is preferably surface-treated with a Nolan coupling agent or the like so that it has good affinity for the matrix resin. . Examples of the N-ran coupling agent include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethquinsilane, N(
Examples include .beta.-aminoethyl)-.gamma.-aminopropyltrintoquinone, and the like. There is no particular restriction on the blending ratio of these 7-run coupling agents, but - for boat fishing, it is preferably 0.05 to 3% by weight based on the weight of mica. Note that a surface treatment agent such as a run coupling agent may be used in advance by surface treatment of mica, but
It is also effective when directly added when melting and kneading resin and mica.

In the present invention, a blowing agent can be added to the composition. There are no particular restrictions on the type of blowing agent, but examples include azonocarbonamide, dinitrosopentamethylenetetramine, p,ρ'-oquinbishenzenesulfonylhydranod), and the like. There is no problem in using these blowing agents in combination, and in combination with blowing aids such as aliphatic metal salts such as carnoum stearate and zinc laurate, and metal acid compounds such as zinc oxide.

A composition using a foaming agent can be foamed during injection molding or extrusion molding, and a molded product with a specific gravity of 0.9 to 1.5 by foaming exhibits excellent performance in specific modulus.

When it comes to materials for acoustic components, the speed of sound is often considered important, and since the speed of sound has a correlation with the specific modulus of elasticity, a molded article made from a resin composition containing a foaming agent is more preferable.

In the present invention, fillers other than those mentioned above, such as glass fiber, talc, carnoum carbonate, barium sulfate, graphite, glass flakes, glass peas, and carbon fiber, can be used in combination with the composition in the present invention, if necessary. Other known additives such as colorants, plasticizers, lubricants, antioxidants, and copper damage inhibitors may be added as necessary.

Normally, in order to knead a resin composition with a high blending ratio of inorganic fillers and organic fillers, uniform kneading cannot be achieved unless a twin-screw extruder with strong kneading power is used. In the present invention, the resin composition is uniformly kneaded using a single-screw extruder with weak kneading power, despite the high blending ratio of the inorganic filler or the inorganic filler containing mica in the resin composition. I can do it. In the present invention, the resin composition is kneaded with each component using a single-screw extruder, twin-screw extruder, roll kneader, etc., and then supplied to an injection molding machine, extrusion molding machine, compression molding machine, etc., and is used to produce acoustic parts, etc. It is molded into various shapes of molded products used in electrical and mechanical applications.

The molded articles of various shapes thus obtained have high elastic modulus, high internal loss, and have a flawless appearance.

[Function] According to the present invention, by adding a specific inorganic filler to a composition consisting of a crystalline aliphatic polyolefin resin and a modified aliphatic polyolefin resin having a certain glass transition temperature, or by further adding mica to the composition, By adding
Despite the large amount of inorganic filler or mica-containing inorganic filler, it can be uniformly kneaded even using a single-screw extruder with weak kneading power, and the inorganic filler is contained in the molded product obtained from the composition. The filler or inorganic filler including mica is uniformly dispersed. Therefore, a molded product with a high elastic modulus and high internal loss and a beautiful appearance can be obtained.

[Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples in any way. In addition, the elastic modulus in the examples was evaluated by dynamic elastic modulus, and each physical property was measured by the following method.

Dynamic modulus of elasticity and internal loss: The dynamic modulus of elasticity E' and internal loss tanδ were measured at a frequency of 110 Hz and at 23° C. using Pyblon DDV-2 manufactured by Toyo Baldwin.

Sink mark: An injection molded product of 130 x 13 x 6 mm was manufactured, and the thickness at the end and center in the cross section in the short side direction was defined as ρ and Q, respectively, and was determined by the following formula.

Sink (%) = X 100 Weight average flake diameter of mica in molded product: After the molded product was treated with waste acid and the resin was burned, the weight average flake diameter of the remaining mica was measured.

Examples 1 to 10 and Comparative Examples 1 to 8 Melt fluorate 15 g/10 min isotactic structure homopolypropylene (J-115G, manufactured by Union Polymer Co., Ltd.), ethyl acrylate copolymerization rate was 40% by weight, Tg Ethylene-dityl acrylate copolymer (EEA copolyethylene, manufactured by Nippon Unicar Co., Ltd.), wollastonite (FPW-400, manufactured by Yosei Kogyo Co., Ltd. or Chemolit S-3, Marujirushi Biochemical Co., Ltd.) with a temperature of -30°C ), a hollow spherical inorganic substance (Zeosphere, manufactured by Maruji Biochemical Co., Ltd.), and mica (Sujirite Mica or Clarite Mica, manufactured by Kuraray Co., Ltd.) in Table 1.
The mixture was kneaded and pelletized using a 40)φ single-screw or twin-screw extruder (Norinder temperature, 230° C.) at the ratio shown in . Next, a box-shaped molded product measuring 130 x 13 x 6 mm was obtained using an injection molding machine with the cylinder temperature set at 230°C. The physical properties of these molded products were measured and the results are shown in Table 1.

Example 11 In Example 1, low-temperature impact-resistant grade polypropylene (J-8158, manufactured by Union Polymer Co., Ltd.) was used instead of the isotactic structure homopolypropylene,
Molded articles were obtained in the same manner except that the proportions of each component were changed to the proportions shown in Table 1. The physical properties of this molded product were measured and the results are shown in Table 1.
Shown below.

Examples 12 and 13 In Example 1, ethylene-isobutyl acrylate copolymer (Tg -28°C) was used instead of ethylene-ethyl acrylate copolymer (Example 12), and ethylene-acrylic acid n- Octyl copolymer (Tg knee 32℃
) (Example I3), a molded product was obtained in the same manner except that the proportions of each component were changed to the proportions shown in Table 1. The physical properties of this molded article were measured and the results are shown in Table 1.

Example I4 In Example 1, high-density polyethylene ()-Izex 5 was used instead of isotactic polypropylene.
Molded articles were obtained in the same manner except that the proportions of each component were as shown in Table 1 using 000S (manufactured by Mikata Petrochemical Co., Ltd.). The physical properties of this molded article were measured and the results are shown in Table 1.

Example 15 A molded article was obtained in the same manner as in Example 1, except that wollastonite and talc were used instead of wollastonite as the inorganic filler, and the proportions of each component were adjusted to the proportions shown in Table 1. The physical properties of this molded article were measured and the results are shown in Table 1.

Margin U Effects of the Invention The present invention provides a resin composition that has a high modulus of elasticity and a high internal loss, and is capable of producing a molded article with a beautiful appearance and few whiskers. This resin composition is suitably used in applications such as speaker boxes, record player cabinets, substrates for driving parts such as motors, and acoustic diaphragms.

Claims (1)

[Claims] 1. (A) crystalline aliphatic polyolefin resin; (B)
an aliphatic polyolefin resin copolymerized with an acrylic acid alkyl ester or a methacrylic acid alkyl ester having a glass transition temperature within the range of -50 to +25°C, and (C)
1. A resin composition comprising at least one inorganic filler selected from wollastonite and hollow spherical inorganic substances, the content of the inorganic filler being 30 to 80% by weight. 2. (A) crystalline aliphatic polyolefin resin and (B)
an aliphatic polyolefin resin copolymerized with an acrylic acid alkyl ester or a methacrylic acid alkyl ester having a glass transition temperature within the range of -50 to +25°C, and (C)
At least one inorganic filler selected from wollastonite and hollow spherical inorganic substances, and (D) mica, and the content of the inorganic filler including mica is 30
80% by weight of a resin composition.