JP3395439B2 - Resin molding - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin molded product used for exterior parts of automobiles and the like. 2. Description of the Related Art For exterior parts such as bumpers and bumper corners used for automobiles, resin moldings are used because of their light weight, low cost, and ease of molding. As the resin molded body, for example, a resin composition composed of polypropylene and rubber, or rubber-modified polypropylene in which polypropylene, rubber and filler are mixed is used. Among them, rubber-modified polypropylene is particularly excellent in impact resistance and is generally used. [0003] However, the above-mentioned conventional rubber-modified polypropylene has the above-mentioned features, but has insufficient weather resistance. Therefore, it is conceivable to add a weather-resistant stabilizer such as an ultraviolet absorber and a light stabilizer. However, in this case, it can be applied to a color having a high light-blocking property such as black or dark gray. After 5 years, there has been a problem that the gloss of the resin molded product is reduced and the color is changed. The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a resin molded article having high weather resistance, high gloss, and excellent discoloration resistance. [0005] The present invention provides a skin layer and a skin layer.
A resin molded body comprising a core layer covered with
The skin layer has a xylene-soluble content of 0 to 20% by weight.
Polypropylene resin, molecular weight less than 1500 and melting point 1
A first hindered amine light stabilizer having a temperature of at least 00 ° C.
Light stabilizer and hindered amine light having a molecular weight of 1500 or more
Contains both a second light stabilizer consisting of a stabilizer and a colorant
The core layer is made of polypropylene resin with rubber.
And / or inorganic fillers
And Izod impact strength (with notch) is 40J / m
(−30 ° C.) or more and a flexural modulus of 300 to 250
Be composed of polypropylene-based composite material of 0 MPa
A resin molded article characterized by the following. The most notable aspect of the present invention is that
The above composition and physical properties with excellent weather resistance, high gloss and discoloration resistance
Skin layer and the above composition and physical properties with excellent impact resistance
Molding with sandwich structure consisting of core layer having
It was in the body. The skin layer is made of the resin composition
The composition and physical properties of the skin layer
Is the same as the above resin composition. In the present invention, the polypropylene resin has a xylene-soluble content of 0 to 20% by weight. Here, the xylene-soluble content indicates the content of a rubber component such as an ethylene / propylene random copolymer contained in the polypropylene resin. If the xylene-soluble content exceeds 20% by weight, the diffusion and volatilization of the weather-resistant stabilizer due to the molecular motion of the rubber component is promoted, and cracks are liable to be generated in long-term outdoor exposure. As the light stabilizer, a hindered amine light stabilizer is used. The hindered amine light stabilizer is a light stabilizer having a hindered piperidine skeleton in the molecule. In the present invention, the following two types are used as a first light stabilizer and a second light stabilizer, and both of them are combined. It used Te. The first light stabilizer is a hindered amine light stabilizer having a molecular weight of less than 1500 and a melting point of 100 ° C. or higher. If the melting point is less than 100 ° C., the stabilizer tends to bleed in the weather resistance deterioration in a high-temperature atmosphere, so that cloudiness occurs on the surface in the initial weather resistance deterioration and the gloss decreases, which is not preferable. On the other hand, the second light stabilizer has a molecular weight of 1
It is a hindered amine light stabilizer of 500 or more. The above molecular weight is less than 1500 and the melting point is 1
As a hindered amine light stabilizer (first light stabilizer) at a temperature of 00 ° C. or higher, for example, as shown in FIG. 1, 1- [2-
[3- (3,5-Di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionyloxy] -2,2,6,6-tetramethylpiperidine, 2-methyl-2- (2,2,6,6-tetramethyl-4-piperidyl) amino-N- (2,2
6,6-tetramethyl-4-piperidyl) propionamide. As the hindered amine light stabilizer having a molecular weight of 1500 or more (second light stabilizer), for example, as shown in FIG. 2, dimethyl-1- (2- (2-dimethyl) succinate) is used.
(Hydroxyethyl) -4-hydroxy-2,2,6,6
-Tetramethylpiperidine polycondensate, poly [｛6-
(1,1,3,3-tetramethylbutyl) amino-1,
3,5-triazine-2,4-diyl {(2,2,
6,6-tetramethyl-4-piperidyl) imino {hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}], N, N'-bis (3-aminopropyl) ethylenediamine- There is a 2,4-bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4piperidyl) amino] -6-chloro-1,3,5-triazine condensate. The first light stabilizer and the second light stabilizer are combined.
In the case of 0.1 part by weight with respect to 100 parts by weight of the polypropylene resin.
It is preferably contained in an amount of 0.5 to 2.0 parts by weight.
If the amount is less than 0.05 parts by weight, the light stability of the resin molded product may be reduced and the resin may be discolored. On the other hand, if it exceeds 2.0 parts by weight, there is a possibility that the mechanical properties are reduced and the formability is reduced. Particularly, in the present invention, since the first light stabilizer and the second light stabilizer are used in combination, a synergistic effect can be obtained with respect to the occurrence of cracks and the change in color difference during outdoor exposure. In addition to the above light stabilizers, hindered phenol stabilizers, phosphorus heat stabilizers, and ultraviolet absorbers are added.
Mixing is preferred. This makes it possible to balance weather resistance, processing heat stability, heat resistance, and the like in a high-temperature atmosphere. Examples of the colorant include inorganic pigments such as titanium white, zinc oxide, zinc sulfide, red iron, chrome yellow, barium yellow, ultramarine, cobalt blue, cobalt green, and carbon black; watching red, permanent red, and para red. , Or toluidine maroon, benzidine yellow, phthalocyanine blue, phthalocyanine green, fast sky blue, or brilliant carmine 6B; it can. In addition, glittering materials such as aluminum powder, aluminum flake, aluminum foil, pearl mica, zinc powder, bronze powder, and glass flake can also be used in combination. Next, as the resin molded body , for example,
A resin molded article comprising a skin layer and a core layer covered by the skin layer, wherein the skin layer comprises a polypropylene resin having a xylene-soluble content of 0 to 20% by weight, and a molecular weight of 1
A first light stabilizer comprising a hindered amine light stabilizer having a melting point of less than 500 and a melting point of 100 ° C. or more, or a molecular weight of 1500
The core layer contains one or both of the above-mentioned hindered amine-based light stabilizer and / or a colorant, and the core layer comprises a polypropylene resin and one or both of a rubber component and an inorganic filler. There is a resin molded body characterized by being comprised of a polypropylene-based composite material having an Izod impact strength (notched) of not less than 40 J / m (−30 ° C.) and a flexural modulus of 300 to 2500 MPa. . In this case, the skin layer has the above-mentioned composition and physical properties excellent in high weather resistance, high glossiness and discoloration resistance, and the core layer has the above-mentioned composition and physical properties excellent in impact resistance. the resin molding of the sandwich structure. The above-mentioned skin layer uses the above-mentioned resin composition, and the composition and physical properties of the above-mentioned skin layer are the same as those of the above-mentioned resin composition. Next, in the present invention, the polypropylene-based composite material in the core layer contains a rubber component and / or an inorganic filler in a polypropylene resin and has an Izod impact strength (notched) of 40.
J / m (−30 ° C.) or more and flexural modulus of 300 to
2500 MPa. Thereby, a core layer exhibiting excellent impact resistance as a bumper can be obtained. Examples of the polypropylene resin for the core layer include homopolypropylene, block polypropylene, random polypropylene, and mixtures thereof. The rubber component is made of amorphous ethylene-
Preferably, it is at least one of an α-olefin copolymer and a styrene-based thermoplastic elastomer. Thereby, appropriate flexibility can be obtained, and strength characteristics such as low-temperature impact resistance can be further improved. The amorphous ethylene-α-olefin copolymer includes propylene as an α-olefin component,
Butene-1, pentene-1, hexene-1, octene
There are 1,4-methylpentene-1, heptene-1 and the like,
One or more of these are used. In addition, SEBS, SEPS, SE
P, SEEPS, SBS, SIS, etc.
Use more than species. The above-mentioned inorganic filler is made of glass fiber,
It is preferably at least one selected from the group consisting of talc, mica, calcium carbonate, wollastonite, clay, barium sulfate, potassium titanate whisker, magnesium sulfate whisker, calcium carbonate whisker, and silica. This can also improve strength characteristics such as low-temperature impact resistance. Further, in the resin molded article of the present invention, since the skin layer is configured as described above, the skin layer is relatively hard. Therefore, it is necessary to configure the core layer to absorb impact energy. However, if the core layer is made flexible to absorb impact energy, the maximum deformation at the time of impact increases, so that only the skin layer breaks and the core layer also breaks due to the notch effect. Conversely, if the rigidity of the core layer is too high, the effect of absorbing impact energy is reduced, and cracks occur in the skin layer. Therefore, in order to satisfy both of the above characteristics, the Izod impact strength (with notch) in the core layer is 40 J / m or more and the flexural modulus is 3
It is necessary to be 00 to 2500 MPa. In the present invention, the xylene-soluble content of the polypropylene resin is 20% by weight or less. This polypropylene resin has a small amount of a rubber component, which is an inhibitor of weather resistance. Therefore, the resin molded article molded from the above resin composition can prevent the occurrence of cracks and exhibit excellent weather resistance. Further, since the occurrence of cracks can be prevented, high gloss can be continuously exhibited for a long period of time. In the present invention, as the hindered amine light stabilizer, a combination of a high molecular weight stabilizer and a low molecular weight stabilizer is used. For this reason, the onset
Light resin moldings are less likely to discolor. Therefore, not only black and dark gray but also coloring agents exhibiting various colors can be used. Therefore, a wide range of colors can be selected , and resin molded bodies of various colors can be formed. Next, the resin molded article of the present invention comprises a skin layer and a core layer provided therein. The skin layer
It is formed using the above specific resin composition.
Therefore, it has excellent weather resistance and discoloration resistance, and can exhibit high gloss. The core layer is made of a polypropylene-based composite material having the specific composition, the specific Izod impact strength (notched), and the physical properties of flexural modulus. Therefore, high impact resistance is exhibited by the core layer.
Therefore, according to the resin molded article of the present invention, in addition to the effect of the skin layer, more excellent impact resistance can be exhibited. According to the present invention, there is provided a resin molded product having high weather resistance, maintaining high gloss, and having excellent discoloration resistance.
It can be. Examples 1 to 5 Examples of the present invention will be described together with comparative examples. In this example, weather resistance and discoloration resistance of a resin molded article molded from the following resin composition were measured. In the measurement, the resin compositions shown in Table 3 were used. In the same table, polypropylene resin is PP
-1 to 4, and five types of rubber-modified PP were used. As shown in Table 1, PP-1 to PP-4 are various polypropylene resins having different xylene-soluble components. As shown in the table, the rubber-modified PP was composed of the composition 6 of PP-3.
0% by weight of ethylene propylene rubber (EPR) 3
0% by weight and 10% by weight of talc were added and mixed. The table also shows the melt flow rate (MFR) of these resins. MFR is JIS 6758
The measurement was carried out under the conditions of 230 ° C. and a load of 2160 g according to As light stabilizers, three types of HALS (hindered amine light stabilizers) 1 to 3 were used. H
ALS1 is 2-methyl-2- (2,2,2) shown in FIG.
6,6-tetramethyl-4-piperidyl) amino-N-
(2,2,6,6-tetramethyl-4-piperidyl) propionamide. HALS2 is bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate shown in FIG. HALS3 is a poly [[6] shown in FIG.
-(1,1,3,3-tetramethylbutyl) amino-
1,3,5-triazine-2,4-diyl] [(2,
2,6,6-tetramethyl-4-piperidyl) imino]
Hexamethylene [(2,2,6,6-tetramethyl-4
-Piperidyl) imino]]. Their molecular weights and melting points are shown in Table 2. In the table, HALS-3 has a softening point of about 120 ° C. and has no particular melting point. The coloring agents shown in Table 4 were used. In addition to the above components shown in Table 3, 0.2 parts by weight of a hindered phenol-based antioxidant and 0.2 parts by weight of a phosphorus-based heat stabilizer were added to 100 parts by weight of the resin composition. 0.1 part by weight of the agent was added and mixed. The chemical structural formulas of the hindered phenol antioxidant and the phosphorus heat stabilizer are shown in FIGS. 4 and 5, respectively. The resin composition is
After kneading using a twin-screw extruder and producing pellets, the mixture was molded into a test piece having a size of 40 mm × 100 mm and a thickness of 2 mm by an injection molding machine. The test pieces were measured for weather resistance and discoloration resistance (especially, cloudiness of the sample surface at the initial stage of deterioration) by the following method. (Weather resistance) The test piece was exposed to an environment of 83 ° C. using SWOM (Sunshine Weather O Meter).
During the test period, the presence or absence of cracks in the test piece was checked as appropriate using a 30-fold magnifying glass. (Discoloration Resistance) The test piece was exposed to an environment of 83 ° C. for 250 hours using SWOM. Then J
The color difference change ΔE ^* was measured according to ISZ8730. Table 3 shows the measurement results. In the same table, “E” in the uppermost column indicates an example, and “C” indicates a comparative example. Next, the measurement results of Table 3 will be described. As can be seen from the table, Examples E1 to E5 according to the present invention are shown.
In each case, the crack generation time was 3200 hours or more, and the color difference change ΔE ^* was as low as 1.0 or less. On the other hand, Comparative Example C
The color difference change ΔE ^* of 1 to C3 was as high as 1.2 or more. This indicates that the resin compositions according to Examples E1 to E5 can provide high weather resistance and discoloration resistance. Next, consideration will be given focusing on the components of the resin composition. First, when the xylene solubles in the polypropylene resin were changed (Examples E1 to E3 and Comparative Example C1),
As the xylene solubles increase, the crack generation time tends to be shorter, and the color difference change ΔE ^* tends to be higher.
In the case of using rubber-modified PP having a xylene-soluble content of 41% by weight (Comparative Example C2), the crack generation time was 1500 hours and the color difference change ΔE ^* was 1.6, which was even worse.
> From this, it can be seen that when the xylene-soluble content is as small as 0 to 20% by weight, the polypropylene resin can prevent the occurrence of cracks, increase the weather resistance, and can maintain beautiful gloss for a long time. Next, the molecular weight and melting point of the hindered amine light stabilizer were changed (Examples E4, E5, Comparative Example C).
3) When a hindered amine-based light stabilizer (HALS-2) having a molecular weight of 480 and a melting point of 83 ° C. was added, clouding occurred in the initial weathering deterioration, and the color difference change ΔE ^* was significantly increased. From this, when one or both of a hindered amine light stabilizer having a molecular weight of less than 1500 and a melting point of 100 ° C. or more, or a hindered amine light stabilizer having a molecular weight of 1500 or more are used as the light stabilizer,
It can be seen that the discoloration resistance is high. [Table 1] [Table 2] [Table 3] [Table 4] Example 6 A resin molded product according to an example of the present invention will be described with reference to FIGS. In this example, an automobile bumper was manufactured as a resin molded product, and its weather resistance, discoloration resistance,
And low-temperature impact resistance. The bumper was manufactured using a sandwich type injection molding machine. The above bumper is shown in FIGS.
It is provided at the front and rear of the car 99. The bumper 9 includes a substantially straight body bumper 90 and left and right corner bumpers 91 and 92. These three members are integrally formed by an adhesive and attached to an automobile. The test bumper in this example is the corner bumper 91 described above. Further, the corner bumper 91 is provided as shown in FIG.
As shown in the figure, the skin layer 915 and the core layer 910 covered by the skin layer 915 are formed by a sandwich injection molding method. In FIG. 8, reference numeral 911 denotes a clip for attaching the bumper to an automobile. In the present embodiment, the characteristic evaluation of the corner bumper is carried out in the corner bumper 91 (9
2 is the same). The corner bumper is a part where high glossiness and scratch resistance are required similarly to the side of an automobile, and the impact resistance as a bumper is also strongly required. In this example, various materials for the skin layer and the core layer were prepared, and the above evaluation was performed. That is, in this example, the material for the skin layer is the resin composition according to Example 1 (see Table 3). A polypropylene resin (hereinafter, referred to as PP) composite material for the core layer is made of PP4.
It consists of 0% by weight, EPR 50% by weight, and talc 10% by weight, and its Izod impact strength (-30 °) is 19%.
It is 0 J / m and the flexural modulus is 450 MPa. E
PR has a Mooney viscosity ML _{1 + 4} (100 ° C.) of 15 and contains 24% by weight of propylene. The average particle size of talc is 2 μm. Next, a test bumper having the corner bumper structure shown in FIGS. 6 to 9 is manufactured by a sandwich molding method using the skin layer material and the core layer PP-based composite material. did. For comparison, a similar test pan bar was prepared using only the skin layer material of Example 1 described above. The above evaluations were performed on these. Weather resistance and discoloration resistance were measured in the same manner as described above. In the low-temperature impact test, the corner bumper (FIGS. 6 and 9) serving as the above-described test bumper was tested at -30 ° C.
After leaving for 3 hours in the atmosphere of
A steel ball having a weight of 1 kg was dropped, and the drop height at which the bumper was broken (cracks and cracks entered) was measured and evaluated as "low temperature impact strength" (Nm). As a result of the above evaluation, it was found that the bumper composed of the skin layer material and the core layer PP-based composite material had a long crack generation time of 4300 hours and a low color difference change ΔE ^* of 0.8. Was. The low-temperature impact strength was higher than 9.8 N · m. On the other hand, the bumper made of only the material for the skin layer of Example 1 showed the same results as those described above in the crack generation time and the color difference change ΔE ^* , but the low-temperature impact strength was as low as 2.0 N · m. Thus, the skin layer made of the above-mentioned specific material exhibits high weather resistance, high glossiness, and discoloration resistance, and the core layer made of the above-mentioned specific PP-based composite material has high impact resistance. It can be seen that the property is exhibited.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a chemical structural formula of a first light stabilizer in the present invention. FIG. 2 is an explanatory diagram of a chemical structural formula of a second light stabilizer in the present invention. FIG. 3 is an explanatory diagram of a chemical structural formula of HALS-2 in Examples. FIG. 4 is an explanatory view of a chemical structural formula of a hindered amine light stabilizer in Examples. FIG. 5 is an explanatory diagram of a chemical structural formula of a phosphorus-based heat stabilizer in Examples. FIG. 6 is a front view of an automobile showing a mounting state of a bumper in a sixth embodiment. FIG. 7 is a perspective view of a corner bumper according to a sixth embodiment. FIG. 8 is a perspective view of a back surface side of a corner bumper according to a sixth embodiment. FIG. 9 is a sectional view taken along line EE of FIG. 7;

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-184365 (JP, A) JP-A-4-7342 (JP, A) JP-A-6-212033 (JP, A) JP-A-7-204 278373 (JP, A) JP-A-4-246534 (JP, A) JP-A-56-98214 (JP, A) JP-A-64-49493 (JP, U) JP-A-59-16257 (JP, U) Japanese Patent Publication No. 4-25975 (JP, B2) Japanese Utility Model Publication No. 64-6566 (JP, Y1) Overleaf: Data bank for CIBA-GEIGY Light Stabilization of Polyolefins, Ciba-Geigy, January 1, 199 58) Field surveyed (Int.Cl. ⁷ , DB name) C08L 23/00-23/36 C08K 3/00-13/08 B60R 19/03

Claims (1)

(57) [Claim 1] A resin molded article comprising a skin layer and a core layer covered by the skin layer, wherein the skin layer has a xylene-soluble content of 0 to 20% by weight. % Polypropylene resin and a molecular weight of less than 1500 and a melting point of 1.
A first hindered amine light stabilizer having a temperature of at least 00 ° C.
The core layer contains both a light stabilizer and a second light stabilizer comprising a hindered amine light stabilizer having a molecular weight of 1500 or more, and a coloring agent. The core layer is made of a polypropylene resin, a rubber component, or an inorganic filler. Contains one or both and has an Izod impact strength (notched) of 40 J / m (-30
℃) or more, and the flexural modulus is 300 to 2500 MPa
A resin molded product comprising a polypropylene-based composite material.