JPH0582424B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a granular or pellet composition containing mica as a main component, which is suitably used in the field of composite materials, particularly as a reinforcing filler for resins, and has good handling properties and performance. [Prior Art] Mica powder has already been widely used as a filler for resins due to its excellent mechanical properties, electrical properties, heat resistance, and other features. [Problems to be solved by the invention] However, mica powder has a lower bulk specific gravity than general-purpose resin fillers such as talc, calcium carbon, barium sulfate, and wollastonite, so it is susceptible to scattering during handling. It has been pointed out that there is a problem of environmental pollution associated with this, and a problem of segregation of resin pellets/mica powder in the hopper of the extruder when kneading with resin using an extruder or the like. Mica can be made into mica powder with a high bulk specific gravity by selecting the grinding method, but when such mica powder is kneaded with resin, it has a poor effect on improving the mechanical properties of the resin, and it is difficult to use for resin. It cannot be said that it is suitable as a filler. Also, as with general-purpose fillers such as talc, calcium carbonate, barium sulfate, and wollastonite, mica powder has the problem of accelerating resin deterioration when filled into resin, especially when heated. It had Although it is possible to improve the deterioration of resin in the presence of mica to a level where there is no practical problem by using a stabilizer for the resin, it is necessary to use a large amount of stabilizer, which reduces the cost. Increase and stabilizer bleed were pointed out as problems. The present invention was carried out with the aim of improving the handling properties of mica powder while retaining its original characteristics as a filler for reinforcing resins, and at the same time reducing the deterioration effect of resins. [Means for Solving the Problems] The present inventors have conducted intensive studies on the development of mica that is easy to handle and has little deterioration effect on resin. The present inventors have discovered that a mica composition having a specific shape obtained by treatment with a binder can simultaneously improve the above-mentioned problems, and have completed the present invention. That is, in the present invention, the weight average flake diameter is 10 to
300 μm and a weight average aspect ratio of 10
or more mica powder and 0.5% by weight of the total composition weight
Above, the bulk specific gravity is 0.6g/cc or more, and the particle size is 0.3~
It is a 10 mm granular or pelleted mica composition. The physical property values shown in this specification are values determined by the measurement method defined below. (a) Weight average flake diameter of mica powder (l) Mica powder was wet classified using standard sieves with various openings, and the results were classified using Rosin−
The mesh size of the sieve is plotted on the Rammlar diagram and allows 50% by weight of the mica powder used for measurement to pass through.
This is the _value calculated from this value using equation (1). l=√2l ₅₀ (1) (b) Weight average aspect ratio of mica powder (a) From equation (2) using weight average flake thickness d and weight average flake diameter l obtained from equation (1). This is the required value. a=l/d (2) In addition, the weight average flake thickness d in equation (2)
is a water surface single particle film method [CECapes and RC
Coleman, Ind.Eng.Chem.Foundam, 12 ,
124, (1973)], it is calculated from equation (3) using the occupied area S of the flakes on the water surface. d=W/ρ(1-ε)S (3) Here, W is the weight of mica used for measurement, S is the area occupied by the mica single particle film on the water surface, ρ is the specific gravity of mica, (1-ε ) is the occupancy rate when mica is in a close-packed state on the water surface, and ρ
2.86 g/cc is used as the value of and 0.9 is used as the value of (1-ε) in the calculation. (c) Bulk specific gravity of mica powder According to JIS K 5101, mica powder falling from a funnel was placed in a receiver with a diameter of 50 mm and a capacity of 100 c.c. using a powder tester PT-D manufactured by Hosokawa Micron Co., Ltd. This is the value calculated from the weight of the container. (d) Bulk specific gravity of mica composition This value is calculated from the volume and weight of a pellet or granular mica composition placed in a 100 c.c. measuring cylinder. The mica used in the present invention can be widely selected from muscovite, phlogopite, biotite, synthetic fluorophlogopite, etc., and is not particularly limited, but muscovite (white mica) ), phlogopite (gold mica) are most preferably used. The mica powder needs to have a specific weight-average flake diameter and weight-average aspect ratio, and it is preferable that the weight-average flake diameter, weight-average aspect ratio, and bulk specific gravity each have values in specific ranges. That is, the weight average flake diameter of the mica powder needs to be 10 to 300 μm, preferably 10 to 200 μm, and more preferably 10 to 100 μm. Flake diameter is 10μm
As mentioned above, granular or pelleted mica compositions (hereinafter simply referred to as granulated compositions) using mica powder of 300 μm or less have a particularly good effect on improving mechanical properties when kneaded with resin. Further, a granulated composition using mica powder having a flake diameter of 10 μm or more has particularly good dispersion when the composition is kneaded with a resin. On the other hand, mica powder having a flake diameter of more than 300 μm is undesirable because it requires an extremely large amount of binder during granulation. In addition, the weight average aspect ratio of mica powder is
It is necessary that it is 10 or more, and more preferably 20 or more. Granulation or pelletization (hereinafter simply referred to as granulation) is easier when the aspect ratio of the mica powder used is lower, but granulation obtained using mica powder with an aspect ratio of 10 or more is easier. When the composition is filled into a resin, the effect of improving the mechanical properties of the resin is particularly good. The bulk specific gravity of mica powder having the above weight average flake diameter and weight average aspect ratio is usually 0.4.
g/cc or less, preferably 0.15 to 0.35 g/cc
cc, more preferably 0.15 to 0.30. When mica powder having a bulk specific gravity exceeding 0.4 g/cc is used, the granulation operation is easy, but the resulting composition tends to be insufficient in improving the mechanical properties of the resin. There is no particular restriction on the lower limit of the bulk specific gravity, but the bulk specific gravity is 0.15g/
It is extremely difficult to produce mica powder of less than cc. In the composition of the present invention, there are no restrictions on the use of mica powder that has been previously treated with a surface treatment agent such as a silane coupling agent or a titanate coupling agent. The epoxy resin, which is the organic binder component used in the present invention, is
Desirably, it is necessary to have fluidity at room temperature, and the viscosity at that time is preferably 1 poise or less. That is, epoxy resins that are liquid at room temperature can be used as they are as the binder component of the present invention, but epoxy resins that are solid can be used after being heated to an appropriate temperature, or used as a solution using an appropriate solvent. or use as an emulsion. Furthermore, for a binder to be used as a solution or emulsion, it is necessary that the epoxy resin as a binder component has substantial fluidity at the temperature at which the granulated composition and resin are kneaded with the solvent or medium removed. It is. The epoxy resin as an organic binder component is not particularly limited as long as it satisfies the above requirements, and epoxy resins, modified products thereof, or blends thereof are used. When the epoxy resin is filled with a granulated composition, it extremely effectively contributes to preventing thermal deterioration of the resin. The content of the epoxy resin as a binder component in the granulated composition is 0.5 to 10% by weight, preferably 0.5 to 5% by weight, and more preferably 0.5 to 3% by weight. Although it is desirable for the binder component to be large in terms of ease of granulation operation and compressive strength of the granulated composition, the mechanical properties of the resin blended with the granulated composition Since it decreases as the binder component increases, the upper limit of the content of the epoxy resin as a binder component in the granulated composition is 10% by weight or less, preferably 5% by weight or less, and more preferably 3% by weight or less. In order to obtain a granulated composition using such a small amount of binder, it is necessary to use mica powder having a specific shape as described above. On the other hand, the lower limit of the content of the binder component is determined as the lowest content at which the mica powder can be substantially granulated and the granulated composition maintains an appropriate compressive strength. When considering heat deterioration resistance when using an epoxy resin as a binder component, it is preferably used in an amount of 0.5% by weight or more, particularly 1% by weight or more. There are no particular restrictions on the method for producing the granulated composition of the present invention, but in general, mica powder and a binder component are sufficiently mixed in a temperature range where the binder component has fluidity, and then mixed under appropriate pressure. Manufactured by agglomerating mica powder in
So-called tumbling flow method, extrusion granulation method, compression granulation method,
A fluidized bed granulation method, a mixed granulation method, etc. can be used. Of these granulation methods, the internal extrusion granulation method or the compression granulation method is a particularly preferred process in that a granulated composition with a high bulk specific gravity can be easily obtained by adding a small amount of a binder component. The bulk specific gravity of the granulated composition in the present invention is
It is necessary that it is 0.6 g/cc or more. A granulated composition with a bulk specific gravity of less than 0.6 g/cc can reduce scattering during handling, but cannot solve the problem of resin pellet/mica segregation in the extruder hopper. The particle size of the granulated composition in the present invention is 0.3 to 10
mm, preferably 0.5 to 5 mm. A granulated composition with a particle size of less than 0.3 mm has a problem with dispersion during handling, while a granulated composition with a particle size of more than 10 mm has a problem with handling when kneaded with a resin. The granulated composition of the present invention has mica powder and an epoxy resin as a binder component as essential components, but there is no problem in containing other components. In other words, other fillers such as talc, calcium carbonate, wollastonite, barium sulfate, clay, silica, etc. can be used together within the range that does not impair the performance of mica, and deterioration inhibitors, stabilizers, lubricants, electrostatic agents, etc. Inhibitors, flame retardants, blowing agents, crosslinking agents, pigments, etc. can also be added. The granulated composition of the present invention is used by being filled into thermoplastic resins and thermosetting resins due to its excellent handling properties and the property that it does not have an adverse effect on thermal deterioration of the resin. There are no particular restrictions on the method of filling the resin with the granulated composition, and methods using a single-screw or twin-screw extruder, kneader, calender roll, etc. can provide good handling of the granulated composition. , easily filled. In particular, conventionally, when kneading mica powder and resin using an extruder, segregation of mica powder/resin pellets in the hopper, fluctuations in the mica content of the manufactured compound based on this, and low There have been problems such as poor feeding from the hopper to the extruder due to bulk specific gravity, but all of these problems can be solved by using the granulated composition of the present invention. [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but these Examples are not intended to limit the present invention in any way. In addition, the flake diameter and aspect ratio of mica powder in Examples indicate the weight average flake diameter and weight average aspect ratio, respectively. Examples 1 to 9 Gold mica A (flake diameter 40 μm, eye aspect ratio 30, bulk specific gravity 0.25 g/cc), gold mica B (flake diameter 280 μm, aspect ratio 70, bulk specific gravity 0.35
g/cc), gold mica C (flake diameter 15μm, aspect ratio 20, bulk specific gravity 0.21g/cc) and epoxy resin emulsion (solids concentration 20wt%, epoxy resin is bisphenol A type, epoxy equivalent 190, viscosity 120poise) ) was used to conduct experiments.
Epoxy resin emulsion was added to gold mica A, B, and C so that the blending ratio of epoxy resin solid content to mica was as shown in Table 1, and the mixture was thoroughly mixed using a double-arm kneader. The mixture is fed to a roll extrusion granulator (disk pelleter),
By extruding and cutting the mixture through a disk die under pressure with a roll, the mixture was cut into pieces with a diameter of about 3 mm.
After shaping into a cylinder with a length of about 5 mm, the pelletized mica composition was mixed by drying at 100° C. for 3 hours. In all cases, granulation properties were good. The pellet-like mica compositions obtained all had a bulk specific gravity of 0.6 g/cc or more, and no dust was observed to be generated during handling. The mica pellets, polypropylene (melt index: 5 g/10 min), and γ-aminopropyltriethoxysilane were mixed in such a manner that the weight fraction of mica in the mixture was 40% by weight, and the weight fraction of γ-aminopropyltriethoxysilane was 40% by weight of the mica. Mix to give a concentration of 0.5% by weight, and transfer the mixture to a single screw extruder (40mm
φ, L/D=28) and cylinder temperature 230
C. and a screw rotation speed of 40 RPM to obtain mica-filled polypropylene. The mica pellets were well absorbed into the hopper of the extruder, and no segregation was observed. Pelleted mica/
When kneading 20 kg of polypropylene, the variation in mica content in the resulting pellets is 40 ± 1% by weight.
It is extremely stable within the range of , and the discharge amount is approximately 11
It was expensive at Kg/hr. The obtained mica/polypropylene pellets were press-molded at 230° C. to form a 0.2 mm thick sheet, and as visually judged, the dispersion of mica into polypropylene was good in all cases. The mica-filled polypropylene was supplied to a screw-in-line injection molding machine with a capacity of 4 ounces, and injection molding was performed at 230°C to obtain a dumbbell-shaped test piece specified in JIS D-638. The tensile strength of the test piece was good as shown in Table 1. In addition, when the test pieces were thermally degraded in a gear oven kept at 140°C and the time required for the tensile strength to decrease to 50% was measured, as shown in Table 1, all compositions showed good values. Indicated. Comparative Example 1 Using gold mica A that is not subjected to granulation treatment,
It was kneaded with polypropylene in the same manner and under the same conditions as in Examples 1 to 9. When gold mica and polypropylene pellets were mixed, significant scattering of mica was observed. Also, significant segregation of the mixture was observed in the extruder hopper, and when 20 kg of mica/polypropylene was kneaded, the mica content in the resulting pellets varied by 39±7% by weight, which was an extremely significant variation. The discharge amount was also 8.5 Kg/hr, which was an extremely low value compared to Examples 1 to 9. The specific tensile strength of the test pieces obtained by injection molding the pellets was almost the same as that of Examples 1 to 9, but the heat deterioration resistance was extremely poor. Details of the results are shown in Table 1. Comparative Example 2 The epoxy resin emulsion used in Examples 1 to 9 was heated to evaporate water to obtain a solid epoxy resin. Using the epoxy resin, a mixture of polypropylene (57 parts)/gold mica A (40 parts)/epoxy resin (3 parts)/γ-aminopropyltriethoxysilane (0.2 parts) was obtained. The mixture was kneaded using an extruder in the same manner and under the same conditions as in Examples 1 to 9, but the behavior at that time was the same as in Comparative Example 1. Problems such as segregation of mica, fluctuation of mica content in pellets, and insufficient discharge amount were observed. As shown in Table 1, the performance of the test piece injection molded from the kneaded product was almost satisfactory in tensile strength, but poor in heat deterioration resistance. Comparative Examples 3 and 4 Experiments were conducted using Gold Mica D (flake diameter 440 μm, aspect ratio 70, bulk specific gravity 0.35 g/cc) and the same epoxy resin emulsion as in Examples 1 to 9. The gold mica D/epoxy resin emulsion mixture could not be granulated using the granulator used in Examples 1 to 9 even when 10% by weight of the epoxy resin component was blended (Comparative Example 3). Although granulation became possible by setting the epoxy resin component to 15% by weight, the composition consisting of the granules and polypropylene had extremely low tensile strength as shown in Table 1. Comparative examples 5 and 6 Gold mica E (flake diameter 5μm, aspect ratio
20, bulk specific gravity 0.20 g/cc) or gold mica F (flake diameter 20 μm, aspect ratio 7, bulk specific gravity 0.28
The same experiments as in Examples 1 to 9 were conducted using the same epoxy resin emulsions as in Examples 1 to 9. Granulation properties were good in all cases. A kneaded product consisting of the granulated pellets and polypropylene was produced using the same extruder and under the same conditions as in Examples 1 to 9, but in the composition of Comparative Example 5, the mica was slightly dispersed in the polypropylene. Reflecting this, the tensile strength of the test piece obtained by injection molding the composition was also somewhat low.
Further, the composition of Comparative Example 6 had no problem with dispersion of mica into polypropylene, but its tensile strength was somewhat unsatisfactory. Comparative Example 7 The same experiment as in Examples 1 to 9 was conducted except that Gold Mica C was used and the epoxy resin component was mixed at 0.3% by weight, but no granules were obtained. Example 10 The same experiment as in Examples 1 to 9 was conducted except that gold mica C was used and the epoxy resin component was mixed at 1% by weight. Although some difficulty was observed in granulation, granulation was possible, and a pellet-like composition with a rather low bulk specific gravity (0.65 g/cc) was obtained. The pellet composition was kneaded into polypropylene and its performance was evaluated, and as shown in Table 1, the handleability and physical properties were good. Comparative Example 8 The same experiment as in Examples 1 to 9 was conducted except that gold mica B was used and the blending ratio of the epoxy resin component was 1% by weight. Although granulation was possible, the granules were poorly compacted, contained powdered mica, and had a low bulk specific gravity (0.52 g/cc). The pellet composition was kneaded with polypropylene using the same equipment and conditions as in Examples 1 to 9, but segregation was observed in the extruder hopper, and the mica content in the resulting pellets varied by 39±. 5% by weight
It was big. The discharge amount was also low at 9.5Kg/hr. Comparative Examples 9 to 11 Gold Mica A and ethylene-vinyl acetate copolymer emulsion (Comparative Example 9), polyvinyl acetate emulsion (Comparative Example 10), SBR emulsion (Comparative Example
11), exactly the same experiment as in Examples 1 to 9 was conducted. All emulsions have a solids concentration of 20
It was prepared and used so as to be % by weight. In all cases, the granulation properties were good and the granules were easy to handle, but the performance of polypropylene blended with the granules was poor in terms of heat deterioration resistance, as shown in Table 1. It was inferior to the compositions of Examples 1 to 9. Examples 11-13 Experiments were conducted with white mica A (flake diameter 40 μm, aspect ratio 35, bulk specific gravity 0.23 g/cc) and the epoxy resin emulsion used in Examples 1-9. In Example 11, a roll-type extrusion granulator (disc pelletizer) similar to those in Examples 1 to 9 was used, but in Example 12, a high-speed rotation type mixing type granulator (pin granulator) was used. In Example 13, granulation was performed using a nonuniform extrusion granulator. In Example 13, a pellet-like composition having the same shape as in Examples 1 to 9 was obtained, whereas in Example 12, a granular composition with an average particle size of 1.6 mm was obtained.
The handleability and performance of these compositions were both good, as shown in Table 1.

【table】

〔Effect of the invention〕

According to the present invention, a pellet-like or granular mica composition is provided, which retains the original characteristics of mica powder as a resin-reinforcing filler and has significantly improved handling properties. And when the mica composition is blended with a resin, compared to conventional mica powder,
It has the feature that the deterioration effect of the resin is reduced.

Claims (1)

[Claims] 1 The weight average flake diameter is 10 to 300 μm,
and mica powder with a weight average aspect ratio of 10 or more and 0.5% by weight or more of the total composition weight Bulk specific gravity with 10% by weight or less of epoxy resin as an essential component
A granular or pelleted mica composition having a content of 0.6 g/cc or more and a particle size of 0.3 to 10 mm.