JPH01204947A - Thermoplastic resin composition for exterior automotive trim - Google Patents

Abstract

PURPOSE:To improve flow characteristics, bending elastic modulus and low-temp. impact strength and to decrease mold shrinkage factor, by compounding a specified propylene-ethylene block copolymer, an ethylene-propylene copolymer rubber and talc. CONSTITUTION:70-90% (wt.%, the same applies hereinbelow), propylene- ethylene block copolymer (A) contg. 5-15% boiling xylene-soluble component, wherein the ethylene content is 20-60% and having an ethylene content of 1-10% in the whole polymer and a melt flow rate of 15-80g/10min, 5-15% ethylene-propylene copolymer rubber (B) having a propylene content of 20-60% and a Mooney viscosity ML1+4 (10 deg.C) of 100-150 and 5-15% talc (D) having a specific surface area of 30,000cm<2>/g or larger, a mean particle diameter of 0.5-2.5mu, an aspect ratio of 3 or larger and a particle size distribution wherein 95% or more of the particle diameter are 5mum or larger and 10-98% thereof are 1mum or smaller are kneaded to obtain a thermoplastic resin compsn. for exterior automotive trim having a melt flow rate of 8g/10min or larger, a bending elastic modulus of 10,000-13,000kg/cm<2>, a high-speed face impact value at -30 deg.C of 8J or higher and a mold shrinkage factor of 9X10<-3> or less.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a filler-reinforced resin composition that has sufficient tensile rigidity and sufficient impact strength at low temperatures as an automotive exterior part, and is inexpensive.

(Prior Art) In recent years, propylene-based resin materials have been increasingly used as conventional automobile exterior parts such as bumpers, fascias, and front fenders. For example, propylene-based resins with improved coating performance, appearance, low-temperature impact strength, etc. have been used for bumpers. Many proposals have been made regarding these improvement methods. That is,
Mainly, attempts have been made to blend ethylene-propylene copolymer rubber to improve coating performance, etc., and to add inorganic fillers such as talc to improve rigidity (JP-A-57-55942, JP-A-57-57). -159841, same 57-
159842, 58-111846, 58-16
8648, 58-213043, 60-1884
Publication No. 53).

(Problems to be Solved by the Invention) However, in such conventional materials, low molecular weight propylene/ethylene block copolymers and
Because ethylene/propylene copolymer rubber was used, the amount of ethylene/propylene copolymer rubber needed to be added was 18% by weight or more, and even though propylene resin was used, it was relatively expensive. There was a problem.

(Means for Solving the Problems) This invention has been made by focusing on such conventional problems, and uses a specific crystalline propylene-ethylene block copolymer as the A component and a specific crystalline propylene-ethylene block copolymer as the B component. The above problems are solved by using ethylene-propylene copolymer rubber and specific talc in specific proportions.

The composition of the present invention has a melt flow rate (MFR) of 8 g/10 minutes or more and a flexural modulus of 10,000 to 13.
,000kg/cm", high-speed surface impact value at -3Q℃ of 8μ or more, molding shrinkage rate of 9X10-3 or less, and high quality for automotive parts, especially automotive exterior parts such as bumpers, fascias, and front fenders. The propylene/ethylene block copolymer (EPP) used as component A in this invention has an ethylene content of 20 to 60% by weight, or 30 to 50% by weight.
5 to 15% by weight, preferably 5 to 10% by weight of boiling xylene solubles, the ethylene content of the entire polymer is 1 to 9% by weight, preferably 5 to 10% by weight, and M
FR is 15-80g/10min, preferably 20-30g
/10 minutes. Here, the ethylene content is a value measured by a conventional method such as infrared spectroscopy or NMR method, and the boiling xylene soluble content is dissolved by immersing 2 g of sample in 600 g of boiling xylene for 20 minutes. This value is calculated back from the solid phase weight determined by cooling to room temperature, filtering with a G4 type glass filter, and drying. If the ethylene content and boiling xylene soluble content of this copolymer are outside the above ranges, the composition will have poor flexural modulus and impact strength at low temperatures and is therefore unsuitable.

Here, if this copolymer is within the above property range, 2
There is no problem even if it is a combination mixture of more than one type of resin, and in that case, the propylene resin outside the above property range is mixed with the above propylene-ethylene block copolymer in the amount (polymer ii)
It can also be used within a range not exceeding.

In addition, this propylene/ethylene block copolymer is
Other unsaturated monomers (for example, butene-1, hexene-1, octene-1) may be added to the extent that the effects of this invention are not significantly impaired.
α-olefins such as 1,4-methylpentene-1; vinyl esters such as vinyl acetate; (meth)acrylic acid (
It may be a ternary or more copolymer (which may be a graft type, random type, or block type) containing a ester), an unsaturated organic acid such as maleic anhydride, or a derivative thereof, etc.). Furthermore, a mixture of these may be used.

Next, the ethylene-propylene copolymer rubber (EPR) used as component B used in this invention has a Mooney viscosity of ML and 4.
(100℃) is 100-150 (preferably 100-1
30) with a propylene content of 20 to 60% by weight. When used individually with component A, component B with a Mooney viscosity of less than 100 has poor coating properties and is likely to cause mold delamination. On the other hand, 150
Larger sizes do not have sufficient flowability, resulting in flow marks and the like, which impairs the appearance quality and deteriorates the processability of bumper molding.

If the viscosity range is 100-150, its EPR
may be a combination of two or more components.

If a propylene content of less than 20% by weight is used,
The resulting composition may lack flexibility, and
When a propylene content of more than 60% by weight is used, the mechanical strength of the composition decreases.

In addition, the talc, which is the component C used in this invention, has a specific surface area of 30.000 cm"/g or more, an average particle size of 0.5 to 2.5 μ, and a particle size distribution of 5 μ or less. It is preferable that the ratio is 95% or more and 1μ or less is 10 to 98%.

If the composition does not fall within the above range, the composition will have poor dimensional stability, poor stiffness-low temperature impact balance, poor paintability, and poor appearance, which is undesirable.

Here, the specific surface area is measured using a constant pressure aeration type specific surface area measuring device, such as powder specific surface area measuring device 5S-100 manufactured by Konsei Seisakusho, based on the so-called air permeation method, which is a conventional method.

Further, the particle size distribution is measured by an integrated distribution value by a light transmission method using a liquid phase sedimentation method. An example of a measuring device is 5A-CP type (for example, 5A-CF2-20) manufactured by Konsei Seisakusho.
Or the SKN type manufactured by Seishin Enterprises (for example, 5KN-1
000 type).

On the other hand, the average particle size is the particle size value at the 50% point in the particle size cumulative distribution curve measured with the same device as the particle size distribution measuring device.

The above-mentioned characteristics of talc dispersed in a resin can be obtained by boiling point extraction of this composition with an organic solvent (for example, immersing and dissolving it in xylene at 130 to 140°C for about 10 hours, and then passing it through a thimble filter paper to extract the talc. The talc extracted by a method such as a method of separating a resin or a method of firing this composition can be determined by the above method.

In addition, the average value of the aspect ratio, which indicates the ratio of either the vertical or horizontal length and thickness of this talc, is preferably 3 or more,
Especially 4 or more is good.

Such talc is produced, for example, by the following classification method. In other words, talc raw stone is crushed using equipment such as a tube mill type crusher, impact type crusher, micron mill type crusher, centrifugal roller type Imond mill, etc., and if fine grinding is required, a micron mill or jet type crusher is used. Dry or wet pulverization is performed using a jet-o-mizer, micronizer, jet bulpelizer, stirring mill (tower mill), vibration mill, colloid mill, etc.

Next, these crushed talcs are processed using equipment such as a cyclone, multilon, micron separator, microplex, cyclone air separator, ultra separator, jetclone, tarasiflon, rake classifier, hydrocyclone, hydraulic classifier, centrifugal classifier, etc. - Dry or wet classification is repeated one or more times to adjust its physical properties.

Next, the blending amounts of the components A to C will be described.

The amount of the propylene/ethylene block copolymer resin as component A blended into the composition of this invention is 70 to 90% by weight. If the blending amount is less than 70% by weight, the resulting composition will have insufficient flexural modulus and will not have the tensile rigidity to be used as an exterior component.
Definitely lacking in confusion. Moreover, if it exceeds 90% by weight, sufficient impact strength at low temperatures cannot be obtained and the function as an exterior component cannot be fulfilled.

Further, the blending amount of the ethylene-propylene copolymer rubber, which is component B, is 5 to 15% by weight. If the amount is less than 5% by weight, the resulting composition will not have sufficient impact strength at low temperatures, and if it exceeds 15% by weight, the flowability of the composition will be insufficient, resulting in poor moldability of the exterior parts, and The appearance quality is also impaired due to the occurrence of flow marks and the like.

The blending amount of talc, which is component C, is 5 to 15% by weight.

If the blending amount is less than 5% by weight, the resulting composition will have insufficient flexural modulus, lack tensile rigidity as an exterior part, lack a solid feel, and be unable to keep the coefficient of linear expansion small.
If it exceeds 5% by weight, sufficient impact strength at low temperatures cannot be obtained, and the function as an exterior component cannot be satisfied.

In addition to the above-mentioned components, the composition of the present invention may contain other additional components as long as the effects of the present invention are not significantly impaired.

These additional components include treated or untreated inorganic or organic fillers other than talc used in this invention; rubber or latex components other than EPR used in this invention;
Thermoplastic resins or thermosetting resins other than PPP used in this invention; In addition, various stabilizers, pigments, dispersants, crosslinking agents, foaming agents, flame retardants, nucleating agents, antistatic agents, paintability improvers, etc. However, the addition of filler as an additional component improves plating properties, paintability, adhesion, gloss, moldability, tapping properties, kneading properties, weld strength, creep resistance, dimensional stability,
Effective for improving heat resistance, etc. In addition, calcium carbonate,
The addition of barium sulfate, titanium oxide, and zinc oxide significantly improves these effects.

The composition of this invention can be used in -screw extruders, twin-screw extruders, Banbury mixers, rolls, belavender plastographs,
It can be manufactured using a common mixer such as a kneader. Usually, it is kneaded in an extruder or the like to form a pellet-like compound and then subjected to processing, but in special cases, the three components can be directly supplied to various molding machines and molded while being kneaded in the molding machine. Alternatively, talc or BPR may be kneaded in advance at a high concentration (with various additives as necessary) to form a masterbatch, which is then diluted separately with peropylene polymer, etc., blended, compounded, and molded. can.

The method of molding the composition of this invention is not particularly limited, and regardless of the molding method such as extrusion molding, blow molding, injection molding, sheet molding, thermoforming, rotary molding, lamination molding, etc., molded products can be processed. Among the invention's effects, injection molding is the most suitable.

The composition of the present invention thus obtained has a melt flow rate of 8 g/10 minutes or more and a flexural modulus of 10,000.
~13,000 kg/cm'', a high-speed impact value at -30°C of 8 J or more, and a mold shrinkage rate of 9 x 10-' or less, and excellent dimensional stability not found in conventional filler-reinforced resin compositions. In addition to being paintable, it has a high balance of physical properties (openability - low-temperature impact), good appearance, and moldability.In addition, it has no noticeable sink marks or warping, and has good printability, adhesion, and scratch resistance. The lines are hardly noticeable and the weld strength and tensile elongation are good.

(Example) The present invention will be specifically described below with reference to Examples. The various measurement methods used here are as follows.

(1) Molding shrinkage rate: Immediately after molding, measure the dimension between two points of the molded product, then leave it at room temperature for a certain period of time, then measure the dimension between the same two points, and calculate the shrinkage rate.

(2) MFR: Based on JIS-7210 (23
0°C, 2,16 kg). However, PE is (190℃, 2.1
6kg) (3) Flexural modulus: JIS-7203
Compliant (23℃).

(4) High-speed surface impact test: Support (hole diameter 50++ua)
Test piece placed on top (100 x 100 x 3 mm)
A dart (tip diameter: 578 inches (approximately 16+r++n)), which is a load sensor, is collided with the specimen at a speed of 11 m/sec, and the impact load on the specimen is measured. The strain energy was calculated and used as the material strength. The measurement temperature is =30°C.

Backyard ±1 Components A to C shown in Tables 1 to 3 are blended as shown in Table 4, and to 100 parts by weight of the blend, 0.08 part by weight of 2.6-t-butyl-p-phenol and tetrakis are added. [After blending 0.1 part of methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate cometaf, it was mixed for 5 minutes with a Henschel mixer, and then mixed with an FCM twin-screw kneader. A test piece was prepared at 210°C and subjected to evaluation.

As a result, as shown in Table 4, the compositions with Nα1 to Nα4 showed a good quality balance, but as a comparative example, the composition with Nα
The composition of α5-8 does not have a sufficient balance of physical properties.

(Effects of the Invention) As explained above, the composition of the present invention has A-C
As is clear from the comparison between Examples and Comparative Examples, by including these ingredients as essential components, they have good fluidity, high bending elastic modulus, no need for partial reinforcing materials, high impact strength at low temperatures, and moldability. It has a low shrinkage rate and is extremely effective for manufacturing automobile exterior parts such as bumpers, fascias, and front fenders.

Patent applicant: Nissan Motor Co., Ltd.

Claims (1)

[Claims] 1.A. A propylene/ethylene block copolymer resin containing 5 to 15% by weight of boiling xylene solubles with an ethylene content of 20 to 60% by weight, and an ethylene content of the entire polymer of 1 to 9% by weight, and Melt flow rate is 1
Propylene-ethylene block copolymer 70-90 wt% B.I. 5-80 g/10 min. Propylene content is 2
0 to 60% by weight, and Mooney viscosity ML_1_+_4
(100°C) 5-15% by weight of ethylene-propylene copolymer rubber of 100-150 C. The essential component is 5 to 15% by weight of talc with a specific surface area of 30,000 cm^2/g or more and an average particle size of 0.5 to 2.5μ, a melt flow rate of 8 g/10 minutes or more, and a flexural modulus of 10,000 to 10,000. 13000kg/cm^2, -
A thermoplastic resin composition for automobile exterior parts, characterized in that it has a high-speed surface impact value of 8 J or more at 30°C and a molding shrinkage rate of 9 x 10^-^3 or less.