JPH10265630A - Reinforced polypropylene composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition excellent in workability, processability, physical properties and appearance by forming a granulated composite filler from a fibrous filler and a flaky filler each having a specified length and diameter and then melting and kneading the composite filler with a polypropylene. SOLUTION: A polypropylene in an amount of 100 pts.wt. is melted and kneaded with 3-50 pts.wt. granulated composite filler which consists of 20-80 wt.% fibrous filler having a mean fiber length of at most 50 μm and an aspect ratio of 5 to 45 and 80-20 wt.% flaky filler having a mean diameter of at most 10 μm and which has a mean diameter of 0.5-5 mm and an apparent specific gravity of 0.20-0.80. It is desirable to use fibrous magnesium oxysulfate as the fibrous filler. The flaky filler used comprises, e.g. talc or mica. In the production, a granulated composite filler is used which is formed by putting a flaky filler comprising a talc or mica powder into a fibrous magnesium oxysulfate slurry obtained by hydrothermal synthesis, wet mixing them to give a homogeneous slurry, filtering the slurry, and then extruding it for granulation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reinforced polypropylene composition capable of providing a molded article having an excellent balance between mechanical strength and impact resistance.

[0002]

2. Description of the Related Art For resin materials for molding such as polypropylene, tensile strength, impact strength,
In order to improve mechanical properties such as rigidity, a method of adding a proper amount of various fillers such as fibrous, plate-like, granular, etc. and kneading them to form a composite material of a resin and an inorganic filler is required. General. In particular, in applications as structural materials such as instrument panels for automobiles, it is necessary to adjust the overall balance of physical properties such as mechanical properties and volume stability under environmental changes.

[0003] In the adjustment of mechanical properties, the addition of fillers such as glass fibers is almost the purpose of imparting rigidity, improving static strength, improving impact strength, and improving volume stability. Although it can be achieved, the surface properties of molded products, especially smoothness, are a problem in applications such as instrument panels, and a filler made of finer fibers with a diameter of 1 μm or less than conventional glass fibers is used to secure such properties. Needed. However, fine fiber fillers having a diameter of 1 μm or less tend to agglomerate, making it difficult to uniformly disperse and orient the fibers in the composite resin. There were problems such as a decrease in strength or a failure to obtain stable strength characteristics.

Also, at present, 10 μm is used as a resin filling material.
Although a plate-like filler having a diameter of m or less is also used at the same time, mechanical properties cannot be imparted as much as a fibrous filler alone, and the overall resin physical property balance cannot be satisfied.

[0005] It is not easy to mix a base resin such as polypropylene in a pellet form or a granular form generally used in ordinary resin processing with a powdery filler due to a difference in shape and density between the two. Therefore, when the inorganic substance and the thermoplastic resin are usually mixed, a method in which both are mixed in advance by a dry mixer such as a V-type blender or a ribbon mixer and then supplied to a melt kneader for a compound is adopted. Blockage due to a bridge at the material supply port and separation of the powder material from the base material and other additives are likely to occur. For this reason, the processability at the time of producing a reinforced composite material is poor, and it is difficult to obtain a uniform composite product. As a result, the physical properties and appearance of the molded product may be poor.

[0006] Further, a base resin such as a pellet or granular polypropylene and a granulated product of a fine fiber filler are mixed in advance with a dry blender such as a V-type blender or a ribbon mixer, and a powdery one. A method of separately supplying a fine filler to a material supply port of a melt kneader has also been practiced. However, even in this method, since the bulk specific gravity of the powdery fine filler is extremely small, it is difficult to uniformly inject the mixture into the kneading machine, and as a result, there is a variation in quality, and a resin composition having good physical properties and good appearance is obtained. In order to leave a problem.

Further, in many cases, pulverized powders of natural minerals are used as the plate-like filler, so that dust is easily generated during kneading, which has a problem of adverse effects on the environment, and furthermore, handling is poor due to poor fluidity.

[0008]

Means for Solving the Problems As a result of diligent studies, the present inventors have found that the inorganic filler has a fibrous shape and a plate shape.
It has been found that the above problems can be improved by mixing the types to obtain a composite filler granulated product. The method of homogeneously mixing the fibrous filler and the plate-like filler can be a slurry state in a wet state, a cake state, or a powder state in a dry state.However, in order to suppress fiber breakage and obtain a stable homogeneous mixed state. For this purpose, mixing with a wet slurry is desirable. That is, in a slurry containing a fine fibrous filler, a powdery plate-like fine filler is charged and wet-mixed, then filtered, granulated, and dried to be easily dispersed at the time of kneading with a thermoplastic resin. It was possible to obtain a granulated product of the composite filler. The following characteristics can be provided in the production of a thermoplastic resin composition using the composite filler granulated product as a filler and in various physical properties of the resin itself. Of course, it is possible to prevent dusting during the production of the composition, but it is possible to promote homogeneous mixing of the resin and the filler, and to provide a resin composition with less variation in quality. In particular, the resin composition using the composite filler granule can characteristically improve the impact resistance characteristics, which is a drawback at the time of filler addition, while maintaining the mechanical properties of tensile strength and bending strength. Quality balance can be improved.

Hereinafter, the present invention will be described in detail. The composite filler according to the present invention has an average fiber length of 50 μm or less, a fibrous filler having an aspect ratio of 5 to 45 20 to 80% by weight, and a plate-like filler 80 to 2 having an average diameter of 10 μm or less.
0% by weight, with an average diameter of 0.5 to 5 mm and an apparent specific gravity of 0.20 to 0.80. Examples of the fibrous filler include fibrous magnesium oxysulfate, potassium titanate, aluminum borate whisker, wollastonite, zonotolite, glass fiber, carbon fiber, metal fiber, and organic polymer fiber. The average fiber length of the fibrous filler is 50 μm or less, preferably 10 to
30 μm. If the average fiber length is longer than 50 μm, it becomes difficult to melt-knead the fibrous filler with a thermoplastic resin such as polypropylene. The aspect ratio is 5-4.
5, preferably 10 to 30. Aspect ratio is 5
If it is smaller than this, the composition does not provide a sufficient reinforcing effect in the physical properties of the composition. On the other hand, if it is larger than 45, it becomes difficult to melt-knead the fibrous filler with a thermoplastic resin such as polypropylene. In the present invention, as the fibrous filler, the average fiber diameter is 0.1 to 2 μm and the average fiber length is 20 μm.
It is preferred to use the following fibrous magnesium oxysulfates.

Although the fibrous filler can be kneaded with the resin as it is, various surface treatments can be applied to improve the dispersibility and the familiarity with the resin base material. A silane coupling agent, stearic acid and its metallic soap are used. When polypropylene is used as a base material, it is particularly desirable to perform a surface treatment with sodium stearate or magnesium stearate in warm water.

The platy filler in the present invention includes talc, mica, clay, glass flake, graphite, alumina flake and the like. The average particle size of the plate-like filler is 10 μm or less, preferably 0.5 to 5 μm.
m. If the average particle size is larger than 10 μm, the physical properties of the composition, particularly the impact resistance, deteriorate. In the present invention,
Pulverized and classified as plate-like filler, average particle size 10μm
It is preferable to use the following talc powder or mica powder.

The proportion of the fibrous filler and the plate-like filler is
20 to 80% by weight of fibrous filler, preferably 25%
75 to 25% by weight, and the content of the platy filler is 80 to 20% by weight, preferably 75 to 25% by weight. 2 fibrous fillers
0% by weight or when the amount of plate-like filler is 2
If less than 0% by weight, the effect of the filler composite,
In particular, the effect of improving the falling impact on the impact resistance of the resin composition is not recognized.

The composite filler of the present invention has an average diameter of 0.5
~ 5mm, preferably 1-3mm, apparent specific gravity 0.20
0.80, preferably 0.20 to 0.60.
If the average diameter is smaller than 0.5 mm, handling becomes poor. On the other hand, if it is larger than 5 mm, the effect of preliminary mixing is reduced due to the difference in particle size from the thermoplastic resin to be dry-mixed. In addition, the apparent specific gravity is 0.20-0.
80, preferably in the range of 0.20 to 0.60, dispersibility during kneading is improved. Apparent specific gravity is 0.2
If it is less than 0, powdering occurs before kneading with the resin, and problems such as prevention of dust generation and blockage of the nozzle cannot be solved. 0.8
If it is larger than 0, the fiber is exposed to high shear during molding, so that the fiber is significantly damaged, and it becomes extremely difficult to defibrate and disperse the resin during kneading.

When fibrous magnesium oxysulfate is employed as the fibrous filler, this material is usually produced in a slurry state by hydrothermal synthesis, so that a wet mixing method can be easily applied. Fibrous magnesium oxysulfate is produced in a slurry state by hydrothermal synthesis, and aggregates of 250 μm or more are removed by sieving or the like.
At this time, the slurry concentration of the fibrous magnesium oxysulfate is desirably 5% or less. Into this, a powdery plate-like fine filler is charged and stirred and mixed by a usual slurry stirrer such as a rotary blade. More desirably, surface treatment is carried out by a conventional method using sodium stearate and magnesium stearate, and after addition, the treated slurry is cooled to room temperature or washed with warm water or the like, and then a powdery plate-like fine filler is charged. Stir and mix.

The mixed slurry is subjected to a water content of 50 to 7 by an ordinary method.
Dehydrate to 0%, preferably 57-62%. Water content 50
%, The strength of the granulated product is weak and adverse effects associated with powder generation occur in the steps after drying. 70% moisture content
In the case described above, the fluidity remains, and it is difficult to maintain the granulated shape, and it is not easy to dry. As the dehydrating device, a normal filtering device can be used, but a vacuum filtering device is preferable.

Next, the dewatered cake is granulated. It is necessary that the fine fibers contained in the cake are not broken during processing, that the formed granules are not powdered in the subsequent drying, storage and supply steps, and that kneading is further performed. It is necessary that the particles are easily dispersed and uniformly oriented. In order to satisfy all of the above conditions,
A granulation method in which the pressing force is small and the shearing of the object to be processed is weak is desired. Rolling granulation, extrusion granulation, compression granulation, etc. are available as granulation methods, but in the present case where the addition of a binder is not allowed, the rolling granulation has low strength of the formed granules and powdering occurs in the post-process Resulting in. In compression granulation, the pressure at the time of molding is high and the shearing of the object to be treated becomes extremely intense. Therefore, fiber damage is also severe, and aggregates remain during kneading with the resin, making dispersion difficult. By applying extrusion granulation, the apparent specific gravity of the obtained granules is 0.20 to 0.8 on a dry basis.
By selecting 0, the granules can be subsequently dried, stored,
It was found that the powder was not powdered in the supply step, and was easily dispersed and uniformly oriented when kneaded.

As the granulator, various extrusion granulators can be used, but a lateral extrusion granulator such as a basket ruler is preferable. Extruded die diameter is 1
５5 mm (φ), preferably 2-3 mm (φ).
After the granulation molding, the moisture is dried to 1% or less by a usual dryer. As a device, a normal dryer can be applied except for a disk dryer or the like which causes a large shear to the object to be processed. An apparatus capable of processing in a stationary state such as a band dryer is more desirable.

It was found that the thus obtained granulated composite filler for adding a resin can be easily fed and kneaded at the time of compounding. The polypropylene composition to which the composite filler has been added has an improved melt flow index (MFI) as compared with a conventional case where each filler is separately fed.
It was expected that a molded product could be obtained easily and in a short cycle in the molding process. Further, the molded product of the polypropylene composition to which the composite filler was added exhibited stable mechanical properties as a whole and some excellent mechanical properties. That is, the measured value of the falling weight impact strength was greatly improved as compared with the conventional dry blend method, and the coefficient of variation of the Izod measured value was reduced, and a stable measured value was obtained. Especially when producing a composite filler by surface treatment only fibrous magnesium oxysulfate,
The effect of improving the falling weight impact strength was significant. Although the cause of the improvement in physical properties is not clear, it is presumed that the filler was easily dispersed at the time of kneading and occupied an excellent orientation in the molded product, and was considered to be due to the combined effect of the dispersed plate-like filler and fibrous filler. Can be

Specific examples of the polypropylene used in the present invention include a homopolymer of propylene and a copolymer of propylene and an α-olefin other than propylene, for example, ethylene, butene-1, hexene-1, and octene-1. Coalescing,
These mixtures are mentioned. Among these, a block polymer of propylene and ethylene can be suitably used. This block polymer can be produced, for example, by copolymerizing propylene and ethylene in the presence of a propylene homopolymer. The content ratio of ethylene in the block copolymer of propylene and ethylene is generally 1 to 20% by weight, preferably 1 to 10% by weight.

The polypropylene composition of the present invention is produced by melt-kneading and compounding 100 parts by weight of polypropylene and 3 to 50 parts by weight, preferably 3 to 30 parts by weight of a composite filler. If the added amount of the composite filler is less than 3 parts by weight, sufficient mechanical strength cannot be imparted to the composition, and if the used amount is more than the upper limit, the appearance of the composition deteriorates.

There is no particular limitation on the method of melt-kneading the polypropylene and the composite filler, and the two can be melt-kneaded using a known extruder. It is preferable to use a machine. The temperature at which the polypropylene and the composite filler are melted and kneaded is not particularly limited as long as it is equal to or higher than the melting point of the polypropylene. However, if the temperature is excessively high, magnesium oxysulfate and the like will be decomposed.

For the purpose of further improving the impact resistance of the composition, an elastomer known per se can be contained. Specific examples of the elastomer include olefin elastomers such as ethylene-propylene rubber and ethylene-propylene-diene rubber, styrene-butadiene rubber, styrene-butadiene-styrene rubber, and styrene-
Styrene-based elastomers such as ethylene-butadiene-styrene rubber and styrene-isoprene-styrene rubber are exemplified. The use ratio of these elastomers is generally 2 to 20 parts by weight per 100 parts by weight of polypropylene.
% By weight.

The composition of the present invention may further contain additives known per se, for example, antioxidants, flame retardants, ultraviolet absorbers, antistatic agents, lubricants, release agents, and colorants. The composition of the present invention can be formed into various molded products by, for example, injection molding, extrusion molding, or compression molding.

Hereinafter, the present invention will be described in more detail with reference to Examples. [Material used] (Magnesium oxysulfate fiber) As the magnesium oxysulfate fiber, a slurry (2% by weight) immediately after synthesis produced in a production process of Ube Chemical Industry Co., Ltd. was used. The fiber length of the magnesium oxysulfate fiber was 15 μm and the aspect ratio was 30. (Talc) Talc used was Fukuoka Talc Co., Ltd. 5000S. It is a pulverized powder having an average particle diameter of 4 μm. (Mica) M-XF manufactured by Kameda Mica Co., Ltd. was used. It is a pulverized powder having an average particle diameter of 6 μm. [Evaluation method] (Apparent specific gravity) Measurement of the apparent specific gravity of the composite filler is based on JIS-
According to K5101. (Powder characteristics) Calculate the fluidity index and jetness index based on Carr's table, which comprehensively evaluates the individual physical properties of the powder, from the powder tester measured by Seishin Co., Ltd. did. -Fluidity index 70-79 Fluidity fairly good 60-69 Fluidity normal 20-39 Fluidity poor-Spoutability index 60-79 Spoutability quite strong 0-24 Spoutability none (Dust generation) According to the Occupational Safety and Health Act (work environment measurement).
Specifically, the working environment was measured when the polypropylene resin and the composite filler were melt-kneaded with a twin-screw extruder. Specifically, air at a position of 0.5 m directly above the machine (1.7 m above the working floor) was sampled, and dust particles of 0.07 μm or more were measured. (Physical Properties of Resin Composite Material) The physical properties of the resin composite material were based on the following measurement methods. -Bending test According to ASTM D-638. -Tensile test According to ASTM D-790. -Dropping impact test It was measured using an instrumented impact tester UTM-5 manufactured by Orientec Co., Ltd. under the conditions of a speed of 4.5 m / sec, a temperature of 23 ° C, and a humidity of 50%. -Izod impact test According to JIS K7110.・ HDT (Deflection temperature under load) ASTM D-64
According to 8.・ MFI (Melt Flow Index) ASTM D
It measured at 230 degreeC according to -1238.

Examples 1 to 4 (Composite filler) A 2% by weight magnesium oxysulfate fiber slurry surface-treated with sodium stearate at 80 ° C. was cooled to room temperature, and then talc powder was blended in each blending ratio. The mixture was mixed in a stirring tank with rotating blades for 30 minutes. The obtained slurry was dehydrated by a vacuum filter to a water content of 57 to 63%. Next, the dehydrated cake was granulated to 2.5 mm (φ) using an extrusion granulator basket looser made by Fuji Paudal, and then dried to a moisture content of 1% or less by a box dryer. Table 1 shows the physical properties of the composite filler of magnesium oxysulfate fiber and talc thus obtained. Liquidity as an item of physical property measurement,
The powder characteristics and apparent specific gravity were measured as indices of handling, and the amount of dust generation was measured as an index of the effect on the working environment. Since this composite filler has an apparent specific gravity higher than that of the raw material magnesium oxysulfate fiber or talc, it has good fluidity and handling. Since the amount of generated dust is smaller than that of the conventional technology, the working environment is improved.

Examples 5 to 6 Talc powder was blended in a magnesium oxysulfate fiber slurry of 2% by weight so as to have each blending ratio, and mixed in a stirring tank equipped with rotating blades for 30 minutes. The obtained slurry was dehydrated by a vacuum filter to a water content of 57 to 63%. Hereinafter, the physical properties of the composite filler of magnesium oxysulfate fiber and talc powder obtained by treating in the same manner as in Examples 1 to 4 are shown in Table 1. Fluidity was measured as an item of physical properties, powder characteristics and apparent specific gravity were measured as indicators of handling, and the amount of dust generated during kneading was measured as an index of influence on the working environment.

Example 7 Mica powder was used in place of talc powder.
Treated as in # 4. Table 1 shows the physical properties of the filler.

[0028]

[Table 1]

(Resin composite material) Ethylene content 3.5%,
100 parts of a crystalline ethylene-propylene block copolymer (EPBC) having a melt flow index (MFI) of 15 g / 10 minutes (230 ° C.), 25 parts of a composite filler shown in Table 1, and Yoshinox BHT as an antioxidant
0.1 part (manufactured by Yoshitomi Pharmaceutical) and Irganox 1010
0.2 part (manufactured by Ciba Geigy) and 0.2 part of magnesium stearate as a dispersant were dry-mixed. Next, the dry mixture was charged from the main feed port of the twin-screw extruder and melt-kneaded at a set temperature of 220 ° C. to obtain a resin composite material. The twin-screw extruder used was PCM30 (double-thread screw, diameter 30 mm, L / D 28.5) manufactured by Ikegai Iron Works. (Production of test piece) The obtained resin composite material was injection-molded with a UBE-MAX D150-10 injection molding machine manufactured by Ube Industries under the conditions of a cylinder set temperature of 220 ° C and a mold temperature of 80 ° C to measure physical properties. Test specimens were manufactured and their physical properties were measured.
Table 2 shows the results. The obtained resin composite material has improved physical properties as compared with the prior art. That is, the surface appearance is excellent,
It can be seen that the MFI is improved, the CV value of the Izod impact value is low, and the drop impact is large and excellent. In particular, when a composite filler is produced by surface-treating only fibrous magnesium oxysulfate, the effect of improving the drop impact is significant.

[0030]

[Table 2]

Comparative Examples 1 to 4 Ethylene content 3.5%, melt flow index 15
A predetermined amount of magnesium oxysulfate fiber shown in Table 9 was added to 100 parts of a crystalline ethylene-propylene block copolymer (EPBC) of g / 10 minutes (230 ° C.) and Yoshinox BHT (manufactured by Yoshitomi Pharmaceutical Co., Ltd.) was used as an antioxidant. .
1 part and Irganox 1010 (made by Ciba Geigy)
0.2 part, and 0.2 part of magnesium stearate as a dispersant were dry-mixed. Next, the dry mixture was charged from the main feed port of the twin-screw extruder, talc powder shown in Table 3 was charged from another feed port, and melt-kneaded at a set temperature of 220 ° C. to obtain a resin composite material. The twin-screw extruder used was PCM30 (double-thread screw, diameter 30 mm, L / D 28.5) manufactured by Ikegai Iron Works. Table 4 shows the measurement results of the physical properties of the composite composition.

[0032]

[Table 3]

Comparative Example 5 Processing was performed in the same manner as in Comparative Examples 1 to 4, except that mica powder was used instead of talc powder. Table 4 shows the measurement results of the physical properties of the composite composition.

Comparative Example 6 The same treatment as in Comparative Examples 1 to 4 was carried out except that only magnesium oxysulfate fiber was used as a filler. Table 4 shows the measurement results of the physical properties of the composite composition.

Comparative Example 7 The same treatment as in Comparative Examples 1 to 4 was carried out except that only talc powder was used as the filler. Table 4 shows the measurement results of the physical properties of the composite composition.

Comparative Example 8 Processing was performed in the same manner as in Comparative Examples 1 to 4, except that only mica powder was used as a filler. Table 4 shows the measurement results of the physical properties of the composite composition.

Comparative Example 9 Talc powder was blended into a 2% by weight magnesium oxysulfate fiber slurry so as to have the blending ratio shown in Table 3, and mixed in a stirring tank equipped with rotating blades for 30 minutes. The obtained slurry was filtered and dried to dehydrate to a water content of 10%. Next, this dehydrated product is 500 kg using a compression molding machine.
After granulation to 2.5 mm (φ) at a pressure of f / cm ² , the mixture was dried with a box drier to a water content of 1% or less. Hereinafter, in the same manner as in Examples 1 to 5, a resin composite material and a test piece were prepared and each physical property was measured.
Table 4 shows the results.

[0038]

[Table 4]

[0039]

As described above, according to the present invention, workability, workability, physical properties, and appearance are obtained by forming a composite filler granulated material from polypropylene, a fibrous filler having specific physical properties, and a plate-like filler. Both can provide an excellent composite polypropylene resin composition.

Claims (6)

[Claims] 1. An adhesive composition comprising 100 parts by weight of polypropylene, 20 to 80% by weight of a fibrous filler having an average fiber length of 50 μm or less and an aspect ratio of 5 to 45, and 80 to 20% by weight of a plate-like filler having an average diameter of 10 μm or less. 0.5 diameter
A reinforced polypropylene composition having excellent impact resistance, obtained by melting and kneading 3 to 50 parts by weight of a composite filler granulated to an apparent specific gravity of 0.20 to 0.80 and a specific gravity of 0.20 to 0.80. 2. The reinforced polypropylene composition according to claim 1, wherein the fibrous filler is fibrous magnesium oxysulfate, and the platy filler is talc powder or mica powder. 3. The reinforcement according to claim 1, wherein the fibrous filler is fibrous magnesium oxysulfate surface-treated with a stearic acid-based metal soap, and the platy filler is talc powder or mica powder. Polypropylene composition. 4. A homogenous slurry obtained by wet mixing a fibrous filler and a plate-like filler is filtered, granulated and dried, and 3 to 50 parts by weight of a composite filler and polypropylene 10 are obtained.
The reinforced polypropylene composition according to claim 1, wherein 0 parts by weight are melt-kneaded and compounded. 5. A plate-like filler of talc powder or mica powder is added to a slurry of fibrous magnesium oxysulfate obtained by a hydrothermal synthesis method, and a wet-mixed homogeneous slurry is filtered, and then granulated by an extrusion granulation method. The reinforced polypropylene composition according to claim 2, wherein 3 to 50 parts by weight of the composite filler obtained by drying and 100 parts by weight of polypropylene are melt-kneaded and compounded. 6. A powdery plate-like filler is added to a slurry obtained by subjecting fibrous magnesium oxysulfate obtained by a hydrothermal synthesis method to a surface treatment with a stearic acid-based metal soap and cooling or washing, and a wet-mixed homogeneous slurry is obtained. 4. The method according to claim 3, wherein 3 to 50 parts by weight of a composite filler obtained by drying and 100 parts by weight of polypropylene are melt-kneaded and compounded after granulation by extrusion granulation after filtration. Polypropylene composition.