JPH0565377A - Reinforced thermoplastic resin composition for meter case - Google Patents

Abstract

PURPOSE:To provide the subject composition which is excellent in light screening ability and heat distortion temperature and also in the rigidity both at high temperature and when it contains absorbed water, and therefore has most suitable performance as the material of a meter case for an automobile. CONSTITUTION:The objective composition comprises 85-50wt.% resin component consisting of 95-60wt.% modified polypropylene containing a polypropylene grafted with an unsaturated acid or its derivative and 5-40wt.% polyamide, the total of the modified polypropylene and the polyamide being 100wt.%, 10-40wt.% glass fibers, and 5-20wt.% titanium oxide.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermoplastic reinforced resin composition. More specifically, it has a particularly excellent light-shielding property,
The present invention relates to a thermoplastic reinforced resin composition for a meter case, which has excellent heat distortion resistance and rigidity retention characteristics at high temperature and when absorbing water.

[0002]

2. Description of the Related Art Thermoplastic resins are used as materials for automobile meter cases because of their good workability and reasonable cost. It is important that the meter case of an automobile does not obscure the display because light from the light source leaks, and it is necessary that the meter case be displayed brighter with the same light source. Therefore, the material for the meter case is required to have a light shielding property and a high light reflectance.

From this point of view, a thermoplastic resin mixed with a white pigment is used to obtain a light-shielding property. Among these, a polypropylene-based composite material in which talc and titanium oxide as a white pigment are mixed has been mainly used from the viewpoint of cost. However, these composite materials have a problem that a large amount of titanium oxide is added in order to impart a light-shielding property. In order to solve this problem, JP-A-56-10
No. 9235 proposes to use talc containing a specific amount of iron or more. However, this method can reduce the compounding amount of titanium oxide, but does not improve the heat distortion resistance and rigidity. For this reason, there have been significant restrictions in practical use such as the thickness and shape of the molded product of the meter case.

Particularly, in recent years, the brightness of the meter case has become more and more required for the purpose of eliminating the difficulty of seeing due to the increase in the number of meters mounted on automobiles and improving the drivability for comfort. Is coming. For this reason,
Since many lamps are attached to the display meter,
There is a problem that the ambient temperature rises to 150 ° C. or more when the lamp is turned on, the partition partitioned by each lamp is deformed, and light leaks to an adjacent section to make the display unclear. In order to solve this problem, the light-shielding limit thickness (minimum thickness that blocks light) is excellent in heat-deformation temperature of 150 ° C or higher and rigidity at high temperature, and also aims to improve fuel efficiency by weight reduction. There has been a long-awaited demand for a thermoplastic resin having a performance of 1 mm or less.

As a method for solving such a problem, Japanese Patent Publication No. 2-40689 proposes a composition obtained by mixing titanium oxide and glass fiber in a thermoplastic resin.
Although this composition has some improvement in heat distortion resistance and rigidity at room temperature as compared with the method disclosed in JP-A-56-109235, it does not reach the performance level required for the recent meter case materials. The reality is that they are far from each other.

[0006]

SUMMARY OF THE INVENTION In view of the above situation, an object of the present invention is to provide a thermoplastic reinforced resin composition for an automobile meter case, which has excellent light-shielding properties, heat distortion resistance and high temperature rigidity. It is to provide things.

[0007]

Means for Solving the Problems The inventors of the present invention have made earnest studies from this viewpoint, and as a result, filled a glass fiber and titanium oxide in a resin part component using a modified polypropylene and a polyamide in a specific composition ratio. It was found that the resin composition described above has excellent light-shielding property, heat-deformation resistance, and high rigidity when formed into a molded product, and performance that does not substantially reduce the rigidity when absorbing water, and has reached the present invention. That is,

The thermoplastic reinforced resin composition for a meter case according to the present invention comprises 95 to 60% by weight of a modified polypropylene having a graft polypropylene grafted with an unsaturated acid or a derivative thereof as a part or the whole.
The resin part component consisting of polyamide in an amount of 5 to 40% by weight, totaling 100% by weight, is 85 to 50% by weight based on the composition, glass fiber is 10 to 40% by weight based on the composition, and titanium oxide is based on the composition. 5 to 20% by weight.

The modified polypropylene using the composition of the present invention is a graft polypropylene grafted with an unsaturated acid or a derivative thereof, or a mixture of the graft polypropylene and an unmodified polypropylene.

The unmodified polypropylene may be a homopolymer of propylene or an α such as propylene and 20% or less by mole of ethylene, 1-butene, 4-methyl-1 pentene or the like.
-A block or random copolymer with olefins.

The graft polypropylene is obtained by reacting an unmodified polypropylene with an unsaturated acid or its derivative in the presence of a radical generator under a heated condition.
As the unsaturated acid, an unsaturated carboxylic acid or an anhydride thereof, such as acrylic acid, methacrylic acid, maleic acid,
Examples thereof include phthalic acid, citraconic acid, maleic anhydride, and itaconic anhydride. Of these, maleic anhydride is particularly preferable. The graft ratio of the graft polypropylene is not particularly limited, but when it is used for the composition of the present invention, the graft polypropylene and the graft polypropylene should not be mixed so that the unsaturated acid or its derivative component is 0.2% by weight or less in the modified polypropylene. It is preferable to adjust the mixing ratio with the modified propylene. Therefore, in the case of a graft polypropylene having a graft ratio of 0.2% by weight or less, it can be used as it is as a modified polypropylene in the composition of the present invention.

The polyamide used in the composition of the present invention is hexamethylenediamine, decamethylenediamine, dodecamethylenediamine 2,2,4- or 2,4,4-trimethylhexamethylenediamine, 1,3- or 1,4.
An aliphatic, alicyclic or aromatic diamine such as -bis (p-aminocyclohexylmethane), m- or -p-xylenediamine and adipic acid, suberic acid, sevalic acid, sebacic acid, cyclohexanedicarboxylic acid,
Consists of polyamides made from aliphatic, cycloaliphatic or aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, polyamides made from lactams such as ε-caprolactam and ω-dodecaractam and their components Copolymerized polyamides, or mixtures of these polyamides are mentioned. Specifically, nylon 6, nylon 66, nylon 610, nylon 9, nylon 6/6
6, nylon 66/610, nylon 6/11 and the like. Among these, nylon 6 and nylon 66
Is preferred.

In the composition of the present invention, the modified polypropylene and the polyamide constitute a resin part component, and the proportion of the resin component in the modified polypropylene is 95 to 60% by weight, preferably 90 to 70% by weight. 95% by weight
If it exceeds, the effect of improving the heat distortion temperature, the rigidity at high temperature, and the light shielding property is small. If the amount is 60% by weight or less, the decrease in rigidity due to water absorption, which is a drawback of polyamide, becomes large.

The polyamide is 5-40% by weight, preferably 10-30% by weight. If it is 5% by weight or less, the effect of improving the heat distortion temperature, the rigidity at high temperature and the light shielding property is small. 40
When the content exceeds 10% by weight, not only the decrease in rigidity due to water absorption, which is a defect of polyamide, becomes large, but also the effect of improving the light shielding property becomes the upper limit.

The glass fiber used in the present invention is a glass chopped strand which is usually produced for resin reinforcement, and it is desirable that the average fiber diameter is 5 to 20 μm and the average fiber length is 0.5 mm or more and 10 mm or less. The glass fiber content is 10 to 40% by weight in the total composition.
If it is 10% by weight or less, the heat distortion temperature and rigidity are insufficient, and if it exceeds 40% by weight, the moldability of the molded product is deteriorated and the commercial value is deteriorated, which is not desirable.

The titanium oxide used in the present invention is not particularly limited, and any commercially available product may be used. The compounding amount of titanium oxide is 5 to 20% by weight in the whole composition. If it is 5% by weight or less, the light-shielding property of the molded product cannot be sufficiently obtained, and if it exceeds 20% by weight, the glass fiber is damaged or the coupling is hindered, so that the heat distortion temperature is lowered, which is not desirable. If the total content of the glass fiber and titanium oxide exceeds 60% by weight in the resin composition, not only will industrial production be difficult, but the molded product will be extremely deteriorated and the commercial value will be impaired.
The blending amount of these inorganic fillers is preferably 60% by weight or less.

The method for producing the composition of the present invention includes, for example, the following methods. (1) A predetermined amount of each of modified propylene, polyamide, glass fiber and titanium oxide is put in a high-speed stirrer, stirred and mixed, and then the resin temperature is adjusted to 2 using a uniaxial or biaxial extruder.
A method of melt-kneading and extruding at 30 to 300 ° C, preferably 230 to 280 ° C. (2) Using an extruder equipped with an intermediate addition port in addition to the normal raw material supply port, a mixture obtained by stirring and mixing a predetermined amount of each of modified polypropylene, polyamide, and titanium oxide is supplied from the normal raw material supply port, A method in which after a sufficient amount of this mixture is melt-kneaded, glass fibers are supplied in a predetermined amount from the midway addition port, melt-kneaded at the above resin temperature, and extruded. Various additives such as an antioxidant, a copper damage inhibitor, a crystal nucleating agent, and a release agent can be used in combination in the composition of the present invention.

[0018]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The physical properties of the composition of the present invention were evaluated by the following methods. 1. Heat distortion temperature: Tested according to JIS K7207 with a load of 18/6 kg / cm ² . 2. Rigidity: (1) 23 ° C according to JIS K7203 when absolutely dry
And the bending elastic modulus measured in an atmosphere of 120 ° C. (2) At the time of equilibrium water absorption, the same test piece as above was exposed in the atmosphere of 23 ° C and RH 50%, and after reaching the equilibrium water absorption rate, 2
The bending elastic modulus was measured in a 3 ° C. atmosphere.

3. Measurement of the limit thickness of light-shielding property: (1) Preparation of a test piece for evaluation Using an injection molding machine at a resin temperature of 250 ° C., a mold having a variable wall thickness of 25 mm width, 25 mm length, and arbitrary wall thickness A test piece was molded. (2) Light-shielding test device The light-emitting device shown in FIG. 1 was used. The apparatus comprises a 12V, 3.4W light bulb 2, a removable black-painted cylinder 3, and an evaluation test piece between the cylinder 1 and the cylinder 3 at the bottom of the white-painted cylinder 1. A diaphragm part 4 for placing is provided, and the light bulb 2 emits light by turning on a switch 6 connected via a power source 5, and light is emitted to a peep part 7 of the cylinder 3. (3) Light-shielding test method The cylinder 3 is removed, and the test piece 8 for measurement is placed on the narrowed portion 4 and attached to the cylinder 3. The power source 5 was turned on, the light bulb 2 was made to emit light, and it was judged whether or not the peep light could be sensed so that the ambient light did not enter the peep part 7. The test pieces having different wall thicknesses were observed, and the minimum wall thickness at which light did not leak was measured with a micrometer.

Example 1 Melt flow containing graft polypropylene (abbreviated as graft PP) having a maleic anhydride graft ratio of 4.1% by weight and 0.2% by weight of Irganox 1010 (manufactured by Ciba-Geigy) as an antioxidant. Late (Temperature 230
Unmodified polypropylene (abbreviated as unmodified PP), polyamide resin (C manufactured by Toray Industries, Inc.) at 25 g / 10 min.
M1017), glass fiber (E made by Nippon Electric Glass Co., Ltd.)
CS03T-461) and titanium oxide (Sakai Chemical Co., Ltd.)
Each of SR-1) manufactured by the present invention was compounded as shown in Table 1 and mixed for 1 minute with a high speed stirrer. This mixture has a caliber of 45 m
m, L / D30 twin screw extruder, melt kneading temperature 25
Extrusion pelletization was performed at 0 ° C. and a screw rotation speed of 200 rpm. The pellets obtained here were dried in a hot air dryer at 100 ° C. for 2 hours, and a predetermined test piece was molded by an injection molding machine at a cylinder temperature of 250 ° C. and a mold temperature of 50 ° C., and subjected to various evaluation tests. The results are shown in Table 1.

Examples 2 to 3 The same procedure as in Example 1 was carried out except that the addition amount of polyamide in the resin component was changed as shown in Table 1.

Examples 4 to 5 The same composition as in Example 2 was used, except that the glass fiber and titanium oxide were changed as shown in Table 1, and the same procedure as in Example 1 was carried out.

Comparative Example 1 The procedure of Example 1 was repeated except that the resin component was 100% by weight of unmodified PP. The results are shown in Table 2.

Comparative Example 2 The procedure of Example 1 was repeated, except that the resin component was 98% by weight of unmodified PP and 2% by weight of grafted PP. The results are shown in Table 2.

Comparative Example 3 Except that the amount of polyamide in the resin component was increased,
The same procedure as in Example 1 was performed. The results are shown in Table 2.

Comparative Examples 4 to 6 The same procedure as in Example 2 was carried out except that the glass fiber and titanium oxide of all the compositions were changed as shown in the table. The results are shown in Table 2.

[0027]

[Table 1]

[Table 2]

As is clear from Tables 1 and 2, Example 1 using the composition of the present invention has a heat distortion temperature and room temperature as compared with Comparative Examples 1 and 2 in which polyamide is not used as a resin component. The flexural modulus and the light shielding property at high temperature were significantly improved.

Examples 2 to 3 and Comparative Example 3 are examples in which the amount of polyamide in the resin component was increased from that of Example 1, but compared to Example 1 at heat distortion temperature, room temperature and high temperature. Although the flexural modulus and the light-shielding property are further improved, in Comparative Example 3 in which the polyamide upper limit of the resin portion is exceeded, not only the decrease in rigidity due to water absorption, which is a drawback of the polyamide, but also the effect of improving the light-shielding property becomes the upper limit. Become.

In Examples 4 to 5 and Comparative Examples 4 to 6, the composition of the resin portion was the same and the compounding amounts of the glass fiber and titanium oxide were changed. However, heat was applied only when these compounding amounts were within the range of the present invention. Performances having both deformation temperature, bending elastic modulus at room temperature and high temperature, and light shielding property are obtained. Outside the scope of the present invention, a composition having a performance that combines these performances has not been obtained.

[0031]

EFFECT OF THE INVENTION The composition of the present invention has excellent light-shielding property and heat distortion temperature, and also has excellent rigidity at high temperature and at the time of absorbing water, and also has the optimum characteristics as a material for a meter case for automobiles. It was found to have performance, and the remarkable effect of the present invention was confirmed.

[Brief description of drawings]

FIG. 1A is a vertical cross-sectional view of a light-shielding test device,
(B) is a plan view of the AA 'portion of (a).

[Explanation of symbols]

 1 cylinder 2 light bulb 3 cylinder 4 diaphragm part 5 power supply 6 switch 7 peep part 8 test piece for measurement

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Claims (2)

[Claims] 1. A modified polypropylene having a graft polypropylene grafted with an unsaturated acid or a derivative thereof as a part or the whole thereof is 95 to 60% by weight, and a polyamide is 5 to 40% by weight, which is a total of 100% by weight. 85 to 50% by weight of the resin part component relative to the composition,
A thermoplastic reinforced resin composition for a meter case, containing 10 to 40% by weight of glass fiber and 5 to 20% by weight of titanium oxide with respect to the composition. 2. The thermoplastic reinforced resin composition for a meter case according to claim 1, wherein the modified propylene is a graft polypropylene grafted with an unsaturated acid or a derivative thereof or a mixture of the graft polypropylene and an unmodified polypropylene.