JP2014201676A - Method for producing resin composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a resin composite material capable of uniformly dispersing flaked graphite in a resin.SOLUTION: There is provided a method for producing a resin composite material in which a filler is dispersed in a resin, wherein when flaked graphite having an aspect ratio in the range of 80 to 1,500 is dispersed by kneading in a resin as a first filler, a second filler having an aspect ratio 6 or less, which is a filler other than flaked graphite, is simultaneously kneaded.

Description

  The present invention relates to a method for producing a resin composite material in which a filler is dispersed in a resin, and particularly to a method for producing a resin composite material in which exfoliated graphite is used as a filler.

  In order to improve the physical properties of the resin, various resin composite materials in which a filler is dispersed in the resin have been proposed. For example, Patent Document 1 below discloses a resin composite material obtained by adding a carbon material such as exfoliated graphite to a thermoplastic resin such as polyolefin. Exfoliated graphite is attracting attention as a flat nanofiller with a large aspect ratio.

JP 2010-254822 A

  Because exfoliated graphite is flat and has a large aspect ratio, it tends to agglomerate. Exfoliated graphite is a graphene laminate. Therefore, since π-π stacking occurs, exfoliated graphite is very likely to aggregate compared to other flat nano fillers. Therefore, even if exfoliated graphite is kneaded with resin, it has been difficult to uniformly disperse exfoliated graphite. For this reason, it has been difficult to obtain the effect of improving physical properties by adding exfoliated graphite.

  The objective of this invention is providing the manufacturing method of the resin composite material which makes it possible to disperse exfoliated graphite uniformly in resin.

  The method for producing a resin composite material according to the present invention is a method for producing a resin composite material in which a filler is dispersed in a resin. In the present invention, when exfoliated graphite having an aspect ratio in the range of 80 to 1500 as the first filler is dispersed in the resin by kneading, the second aspect ratio is 6 or less, and the second filler is made of a filler other than exfoliated graphite. The filler is kneaded simultaneously.

  In the method for producing a resin composite material according to the present invention, an inorganic filler is preferably used as the second filler. More preferably, the second filler is at least one selected from the group consisting of mica, talc, silica, zirconia, and alumina.

  In the present invention, the weight ratio of the second filler to the first filler is preferably in the range of 0.2 to 10.

  In the present invention, the resin is not particularly limited, but a thermoplastic resin can be suitably used.

  According to the method for producing a resin composite material according to the present invention, since the second filler having a small aspect ratio is kneaded at the same time, re-aggregation of exfoliated graphite released by kneading can be effectively suppressed. . Therefore, it is possible to provide a resin composite material in which exfoliated graphite is uniformly dispersed.

  Details of the present invention will be described below.

(resin)
The resin used in the method for producing a resin composite material according to the present invention is not particularly limited. That is, as the resin, a synthetic resin, a natural resin, a semi-synthetic resin, or the like can be used as appropriate. As the synthetic resin, a thermoplastic resin or a thermosetting resin may be used. Preferably, a thermoplastic resin is desirable because it is easy to disperse exfoliated graphite by melt kneading.

  It does not specifically limit as a thermoplastic resin, A well-known various thermoplastic resin can be used. Specific examples of the thermoplastic resin include polyolefin, polystyrene, polyacrylate, polymethacrylate, polyacrylonitrile, polyester, polyamide, polyurethane, polyethersulfone, polyetherketone, polyimide, polydimethylsiloxane, and polycarbonate. Examples include a copolymer of at least two monomer components among the monomer components. The thermoplastic resin contained in the resin composite material may be one type or two or more types.

  Polyolefin is preferable as the thermoplastic resin. Polyolefin is inexpensive and easy to mold under heating.

  Examples of the polyolefin include polyethylene, polypropylene, ethylene homopolymer, ethylene-α-olefin copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester copolymer, ethylene-acetic acid. Polyethylene resins such as vinyl copolymers, polypropylene resins such as propylene homopolymers, propylene-α-olefin copolymers, butene homopolymers, homopolymers or copolymers of conjugated dienes such as butadiene and isoprene, etc. Is mentioned. As the thermoplastic resin, a polypropylene resin is particularly preferable.

  More preferably, as the polyolefin, polypropylene having an MFR (measured in accordance with JIS K7210 at a temperature of 190 ° C. and a load of 2.16 kgf) of 0.1 to 20 g / 10 min, A polyethylene or a mixture thereof having a measurement of 0.1 to 20 g / 10 min at a temperature of 2 ° C. and a load of 2.16 kgf is used. In that case, impact resistance can be effectively improved.

  Although it does not specifically limit as said thermosetting resin, An epoxy resin, a phenol resin, unsaturated polyester resin, a thermosetting polyimide etc. can be mentioned.

(Flaky graphite)
In the present invention, exfoliated graphite is a laminate of graphene sheets. Exfoliated graphite can be obtained by exfoliating graphite. That is, exfoliated graphite is a laminate of graphene sheets that is thinner than the original graphite.

  The exfoliated graphite used in the present invention is required to have an aspect ratio in the range of 80 to 1500, and more preferably in the range of 100 to 1000. In the present invention, the aspect ratio of exfoliated graphite refers to the ratio of the maximum dimension in the laminate surface direction of exfoliated graphite to the thickness of exfoliated graphite.

  When the aspect ratio is 80 or more, exfoliated graphite is likely to aggregate. However, according to the present invention, exfoliated graphite having an aspect ratio of 80 or more can be reliably and uniformly dispersed by the addition effect of the second filler. Further, since the aspect ratio is 1500 or less, it is difficult to break during kneading.

  As described above, exfoliated graphite used in the present invention has a large aspect ratio. Therefore, when uniformly dispersed in the resin, it is possible to sufficiently enhance the reinforcing effect against the external force applied in the direction intersecting the graphene sheet lamination surface in the exfoliated graphite.

  The number of graphene sheets laminated in exfoliated graphite is 2 or more. From the viewpoint of effectively increasing mechanical strength such as tensile elastic modulus of the resin composite material, the number of laminated layers is preferably 1000 or less, and more preferably 150 or less.

  The average particle size of exfoliated graphite is preferably about 0.1 to 50 μm. The average particle size of exfoliated graphite is a value measured by a particle size distribution measuring device.

  The exfoliated graphite is commercially available and can be produced by a conventionally known method. For example, exfoliated graphite is a chemical treatment method in which ions such as nitrate ions are inserted between the graphite layers, a heat treatment method, a physical treatment method such as applying ultrasonic waves to graphite, and electrolysis using graphite as a working electrode. It can be obtained by a method such as an electrochemical method.

  The exfoliated graphite may be surface-modified. Examples of the surface modification treatment include a treatment of grafting a resin on the surface of exfoliated graphite, or introducing a hydrophilic functional group or a hydrophobic functional group into the surface of exfoliated graphite. By subjecting exfoliated graphite to a surface modification treatment, the affinity between exfoliated graphite and the thermoplastic resin can be increased. If the affinity between exfoliated graphite and the thermoplastic resin is increased, the mechanical strength such as the elastic modulus of the resin composite material is increased.

  Preferably, a resin such as the thermoplastic resin used as a matrix resin of the resin composite material in the present invention is grafted on the surface of exfoliated graphite. Thereby, dispersibility and affinity of the exfoliated graphite for the matrix resin can be enhanced. Therefore, the mechanical strength can be further increased.

  The method of grafting the thermoplastic resin on exfoliated graphite is not particularly limited, and a method of melt-kneading a thermoplastic resin, exfoliated graphite, and a radical initiator can be used. Examples of the radical initiator include peroxides such as benzoyl peroxide and dicumyl peroxide, peroxide compounds, azo compounds, and dihalogen compounds. In this case, it is desirable to graft the above-described thermoplastic resin as a matrix resin onto exfoliated graphite. In that case, the thermoplastic resin, exfoliated graphite, and a radical initiator are melt-kneaded, and the thermoplastic resin is grafted onto the exfoliated graphite, and the thermoplastic resin, exfoliated graphite, and a second filler described later are included. May be kneaded to obtain a resin composite material.

  However, exfoliated graphite in which the same or different thermoplastic resin as that of the thermoplastic resin is previously grafted to the thermoplastic resin as the matrix resin and the second filler may be mixed to obtain a resin composite material. .

  The exfoliated graphite is contained in the range of 0.1 to 40 parts by mass with respect to 100 parts by mass of the resin. By including 0.1 mass part or more, mechanical strength and impact resistance can be improved. More preferably, it is desirable to contain 10 parts by mass or more. Thereby, the mechanical strength and impact resistance can be further increased.

  Moreover, since the blending ratio of the exfoliated graphite is 40 parts by mass or less, cracking of the resin composite material can be suppressed, and impact resistance can be improved. More preferably, exfoliated graphite is contained at a ratio of 20 parts by mass or less.

(Second filler)
In the method for producing a resin composite material of the present invention, a second filler having an aspect ratio of 6 or less and different from exfoliated graphite is used.

  It does not specifically limit as a 2nd filler different from exfoliated graphite, A well-known inorganic filler can be used. Specific examples of the inorganic filler include calcium carbonate, silica, zinc oxide, aluminum oxide, titanium oxide, magnesium oxide, aluminum hydroxide, magnesium hydroxide, aluminum nitride, barium sulfate, mica, talc, clay, bentonite, montmorillonite, and kaori. Examples thereof include knight, wollastonite, potassium titanate, and glass fiber. The second filler contained in the resin composite material may be one type or two or more types.

  Preferably, since it is inexpensive and easily available, and the second filler itself has a reinforcing effect, the second filler is at least selected from the group consisting of mica, talc, silica, zirconia and alumina. One type is used.

  The aspect ratio of the second filler is 6 or less. Here, the aspect ratio refers to the ratio of the long side to the short side when the second filler has a shape having a long side and a short side. In addition, when the second filler has a shape having a major axis and a minor axis, the ratio of the major axis to the minor axis is used. In other words, when the inorganic filler has a length direction, the maximum dimension in the length direction, and when there is a minimum external dimension other than the length direction and the smallest distance, the maximum dimension in the length direction, The ratio with the above-mentioned minimum external dimension shall be said.

  In the present invention, the aspect ratio of the second filler is as small as 6 or less. By simultaneously kneading the second filler having such a small aspect ratio, it is possible to suppress the re-aggregation of the graphene sheet or the graphene sheet laminated body caused by the release of the exfoliated graphite. This is presumably because the second filler having a small aspect ratio enters between the graphene sheets dispersed by kneading or between the graphene sheets of the graphene sheet laminate, thereby suppressing reaggregation. Therefore, the aspect ratio of the second filler needs to be 6 or less.

  Although not particularly limited, the average particle size of the second filler is preferably in the range of 0.2 to 20 μm. By using the second filler having an average particle diameter within this range, both mechanical strength and impact resistance can be enhanced. More preferably, the average particle size of the second filler is 5 μm or less. In that case, physical properties such as impact resistance can be effectively enhanced.

  The weight ratio of the second filler to the first filler is preferably in the range of 0.2-10. By using the second filler and the first filler at such a ratio, the aggregation of graphene sheets in exfoliated graphite as the first filler can be more effectively suppressed. Therefore, the mechanical strength can be further increased. Preferably, this weight ratio is in the range of 0.2-8.

(Additive)
In the method for producing a resin composite material according to the present invention, various additives may be used as optional components in addition to the above essential components.

  Additives include, for example, antioxidants such as phenols, phosphoruss, amines, and sulfurs; ultraviolet absorbers such as benzotriazoles and hydroxyphenyltriazines; metal hazard inhibitors; hexabromobiphenyl ether, decabromo Halogenated flame retardants such as diphenyl ether; flame retardants such as ammonium polyphosphate and trimethyl phosphate; various fillers; antistatic agents; stabilizers;

(Production method)
In the method for producing a resin composite material according to the present invention, when the resin as an essential component and exfoliated graphite are kneaded, the second filler is kneaded simultaneously. As long as the resin and exfoliated graphite are kneaded in the presence of the second filler, the specific steps of the production method are not particularly limited. For example, the following 1st-4th methods are mentioned.

  First method: First, a resin, exfoliated graphite, and a second filler are prepared. Next, the resin, exfoliated graphite and the second filler are kneaded. In this case, the resin, exfoliated graphite and the second filler are kneaded simultaneously.

  Second method: Kneading resin and second filler, adding exfoliated graphite, and kneading.

  Third method: After the exfoliated graphite and the second filler are kneaded, the resin is added and kneaded.

  Fourth method: After kneading exfoliated graphite and resin, a second filler is further added and kneaded. In this case, re-agglomeration may occur in the exfoliated graphite before the addition of the second filler. However, when the second filler is added and further kneaded, the exfoliated graphite is again unframed, and the second Reaggregation is suppressed by the effect of the filler. However, it is desirable that the exfoliated graphite is kneaded with the resin for the first time in the presence of the second filler as in the first to third methods. Thereby, reaggregation can be more reliably suppressed.

  When the resin is a thermoplastic resin, the kneading is preferably performed at a temperature at which the thermoplastic resin melts. The kneading method is not particularly limited. Examples thereof include a method of kneading under heating using a kneading apparatus such as a twin screw kneader such as a plast mill, a single screw extruder, a twin screw extruder, a Banbury mixer, and a roll. Among these, a method of melt kneading using a plast mill is preferable.

  Furthermore, the resin composite material obtained by the present invention can be formed into various shapes using an appropriate shaping method. As such a shaping method, a molding method such as press working, injection molding or extrusion molding can be suitably used. Furthermore, you may shape by a melt-coating method. Using the shaping method as described above, a desired shape such as a sheet shape can be obtained. In particular, in the molded article of the resin composite material according to the present invention obtained by various molding methods, mechanical strength and impact resistance can be effectively increased.

(Examples and Comparative Examples)
Hereinafter, the present invention will be further described based on specific examples. In addition, this invention is not limited to a following example.

(Exfoliated graphite used)
Graphite or exfoliated graphite as the first filler: graphite or exfoliated graphite having aspect ratios of 10, 100, 180, 1000 and 2000 were prepared. More specifically, the following commercially available exfoliated graphite was used.

Graphite 1: manufactured by SEC Carbon Co., product number: SNO5, aspect ratio = 10
Exfoliated graphite 2: manufactured by XGScience, product number: xGnP-H5, aspect ratio = 100
Exfoliated graphite 3: manufactured by XGScience, product number: xGnP-M5, aspect ratio = 180
Exfoliated graphite 4: manufactured by XGScience, product number: xGnP-C750, aspect ratio = 1000
Exfoliated graphite 5: manufactured by Angstrom, product number: N002, aspect ratio = 2000

(Second filler)
As the second filler, talc, mica, silica, zirconia, and alumina were prepared.

Talc: manufactured by Nippon Talc Co., Ltd., product number: L-1, aspect ratio = 4
Mica: manufactured by Shiroishi Calcium Co., Ltd., trade name: Takara Mica M-101, aspect ratio = 5
Silica: manufactured by Kinsei Matec Co., Ltd., crystalline silica, aspect ratio = 1
Zirconia: manufactured by IMEX, product number: YTZ, aspect ratio = 1
Alumina: manufactured by Sumitomo Chemical Co., Ltd., product number: A-21, aspect ratio = 1

  As for mica, in Comparative Examples 3 and 4, mica manufactured by Shiroishi Calcium Co., product number: ST-501, aspect ratio = 10, mica manufactured by Shiraishi Calcium Co., product number: ST-509, aspect ratio = 110, respectively. Was used.

(resin)
A mixture of two types of polypropylene produced by Nippon Polypro Co., Ltd. was used by 50% by weight. That is, made by Nippon Polypro Co., Ltd., polypropylene, product number: MA3H (MFR = 10 g / 10 minutes, weight average molecular weight of about 250,000) and product number: EA9 (MFR = 0.5 g / 10 minutes, weight average molecular weight of about 550,000) A resin containing 50% by weight was used.

Example 1
10 parts by weight of exfoliated graphite 3 (aspect ratio = 180) and talc (aspect ratio = 4) are blended with 100 parts by weight of the resin, respectively, and a lab plast mill R-100 manufactured by Toyo Seiki Seisakusho is used. The resin composition was obtained by melt-kneading at a temperature of 180 ° C. This resin composition was molded by a press device manufactured by Shinko Seiki Co., Ltd. to obtain a sheet-like molded body.

(Examples 2 to 15 and Comparative Examples 1 to 4)
A resin composition was obtained by melt-kneading in the same manner as in Example 1 except that exfoliated graphite and the second filler used were changed as shown in Table 1 below. Moreover, it carried out similarly to Example 1, and shape | molded the obtained resin composition, and obtained the molded object.

(Comparative Example 5)
A resin composition was obtained in the same manner as in Example 1 except that the second filler was not added, and was molded in the same manner to obtain a molded body.

(Comparative Example 6)
A resin composition was obtained in the same manner as in Example 1 except that exfoliated graphite was not added, and molded in the same manner as in Example 1 to obtain a molded body.

(Comparative Example 7)
Without using exfoliated graphite and the second filler, only the resin used in Example 1 was molded in the same manner as in Example 1 to obtain a molded body.

(Evaluation method)
(1) Aspect ratio of exfoliated graphite and second filler: The aspect ratio of exfoliated graphite and second filler was observed with an electron microscope, and the length and thickness were measured. That is, the length and thickness of a large number of exfoliated graphite or second filler obtained by observing with an electron microscope were measured, and an average value thereof was obtained. And the aspect-ratio was calculated | required by the average value of length, and the average value of thickness.

  (2) Tensile elastic modulus: About the obtained sheet having a thickness of 0.5 mm, a test piece having a plane shape of 75 mm in length and 6 mm in width was cut out. About this test piece, the tensile elasticity modulus in 23 degreeC was measured based on JISK7161. The results are shown in Table 1 below.

  (3) Dispersibility evaluation: The obtained composite material sheet was sliced, the cross section was observed with an electron microscope, and the ratio of exfoliated graphite exceeding a predetermined area was measured. That is, the dispersibility was evaluated by determining the ratio of graphene to the total exfoliated graphite appearing in the field of exfoliated graphite that re-agglomerates and exceeds a predetermined area.

More specifically, the cross section of the composite material sheet was observed at a magnification of 1000 times using a scanning electron microscope. Within this field of view, the ratio (%) of the exfoliated graphite having a cross-sectional area of 10 μm ² or more to the total exfoliated graphite was determined. And it evaluated according to the following evaluation symbol. The results are shown in Table 1 below.

○: 16% or less △: Over 16%, 20% or less ×: Over 20%

  As apparent from Table 1, in each of Examples 1 to 3, exfoliated graphite was uniformly dispersed and the tensile modulus was sufficiently large. In addition, since the aspect ratio of exfoliated graphite increases in the order of Example 2, Example 1, and Example 3, the tensile modulus increases as Example 2, Example 1 to Example 3 increase. I understand that.

  In Examples 4 to 6, the amount of talc as the second filler is changed as compared with Example 1, but in any case, the dispersibility of exfoliated graphite is relatively good and the tensile modulus is also high. it was high.

  In Example 7, re-aggregation of graphene in exfoliated graphite was partially recognized. This is probably because the blending ratio of the second filler is high and the absolute amount of the second filler is large. However, also in Example 7, compared with Comparative Examples 1-5, the dispersibility of exfoliated graphite is fully improved.

  In Examples 8 to 11, the type of the second filler is different from that in Example 1. In any case, exfoliated graphite was uniformly dispersed and the tensile modulus was sufficiently large. In Examples 12 and 13, the addition amount of exfoliated graphite and the second filler is varied in a state where the types and weight ratios of exfoliated graphite and the second filler are fixed. In Example 12, the exfoliated graphite and the second filler are both as small as 1.5 parts by weight. In Example 12, the tensile modulus was slightly low, but the dispersibility of exfoliated graphite was good.

  On the other hand, in Example 13, 90 parts by weight of exfoliated graphite and the second filler were blended. In this case, since the blended amounts of exfoliated graphite and the second filler are large, the tensile elastic modulus is dramatically increased.

  In Examples 14 and 15, the blending ratio of exfoliated graphite was 10 parts by weight, and the blending ratio of talc as the second filler was changed. Also in this case, it can be seen that the tensile elastic modulus slightly changes according to the blending ratio of talc.

  In Comparative Example 1, since the aspect ratio of graphite 1 was as low as 10, the dispersibility of graphite was insufficient and the tensile modulus was low.

  In Comparative Example 2, the dispersibility of exfoliated graphite was also low because the aspect ratio of exfoliated graphite was too large as 2000. This is presumably because exfoliated graphite 5 having an excessively high aspect ratio is deformed or broken during kneading.

  In Comparative Examples 3 and 4, since the aspect ratio of the second filler was too large, the tensile elastic modulus was low and the dispersibility of exfoliated graphite was also low.

  This is presumably because the effect of suppressing re-aggregation in exfoliated graphite is reduced because the aspect ratio of the second filler is too large.

Claims (5)

A method for producing a resin composite material in which a filler is dispersed in a resin,
When the exfoliated graphite having an aspect ratio in the range of 80 to 1500 as a first filler is dispersed in the resin by kneading, a second filler that is a filler other than exfoliated graphite and has an aspect ratio of 6 or less is used. A method for producing a resin composite material, which is kneaded simultaneously.   The method for producing a resin composite material according to claim 1, wherein the second filler is an inorganic filler.   The method for producing a resin composite material according to claim 2, wherein the second filler is at least one selected from the group consisting of mica, talc, silica, zirconia, and alumina.   The manufacturing method of the resin composite material of any one of Claims 1-3 whose weight ratio of a said 2nd filler and a said 1st filler is the range of 0.2-10. The method for producing a resin composite material according to claim 1, wherein a thermoplastic resin is used as the resin.