JP2004244490A - Carbon nanotube-containing resin composite and method for producing the same, and high-modulus film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbon nanotube-containing resin composite which is imparted with excellent mechanical properties inherent in a carbon nanotube. <P>SOLUTION: The carbon nanotube-containing resin composite is a resin composite in which a monolayer and/or a multilayer carbon nanotube coated with a conjugated polymer is dispersed in a resin with a side chain structure, wherein a percentage composition of a carbon nanotube to the resin is from 0.01 wt% to 1 wt%. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a carbon nanotube-containing resin composite having a high elastic modulus, a method for producing the same, and a high elastic film comprising the resin composite.
[0002]
[Prior art]
Addition of fillers to resins has been widely used as a technique for improving mechanical properties, for example, tensile strength and elastic modulus, and for obtaining resin composites having desired properties. As such a reinforcing filler, a fibrous or needle-like filler is used as a reinforcing filler.For example, as a fibrous filler, glass fiber, carbon fiber, aramid fiber, etc. , Zonotrites and the like are known.
[0003]
Properties required as a filler for resin reinforcement include: 1. High strength and elastic modulus; 2. low density; 3. small variation in size; Good adhesiveness with a resin is mentioned.
[0004]
In recent years, nanotubes have been attracting attention as a promising fibrous filler for the above 1 to 3 above. A nanotube is a tubular molecule formed by a network of chemical bonds. A typical example is a carbon nanotube (hereinafter, referred to as CNT) in which a graphite-type carbon forms a tubular network. Discovery has also been reported for BCN nanotubes and BN nanotubes that are partially or entirely replaced by boron (B) or nitrogen (N). In addition, it has been reported that CNT can be chemically modified relatively easily, such as by introducing a carboxyl group into a defect portion of a graphite structure or a terminal portion of a nanotube by performing an acid treatment. I have. For example, chemically modified CNT in which various functional groups are introduced by esterification or amidation using the carboxyl group as an anchor, fluorinated CNT in which graphite structure is fluorinated, and the like are known.
[0005]
Each nanotube has a length of about several tens nm to several tens μm, while the diameter is about 1 to 50 nm, which is very fine and elongated, and has a large aspect ratio. Further, the density is small because of the tube shape. In particular, CNTs have high elasticity and high strength compared to any existing materials, and have useful properties such as the structure does not change even at high temperatures. Therefore, CNTs are structural materials and resin composites with excellent mechanical properties. Application development is under way.
[0006]
Some examples of a resin composite using CNT as a filler for reinforcing a resin have been reported so far. For example, Non-Patent Document 1 discloses a method of dispersing CNTs using polymethyl methacrylate (PMMA) as a matrix resin. In this method, uniform dispersion of CNTs is required unless repeated steps are performed several hundred times or more. Is very complicated and inefficient. Further, this document describes that the elastic modulus increases in the fiber drawn after dispersing the CNT, but it is considered that only the effect of dispersing the CNT can be evaluated. Extrapolation of the elastic modulus value from the data of the same document shows little improvement.
[0007]
[Non-patent document 1]
"Chemical Physics Letters", Vol. 330, 2000, p. 219
[Problems to be solved by the invention]
As described above, in the conventional method, the interaction between the matrix resin and the CNT in the CNT-containing resin composite is generally small. Therefore, it is difficult to sufficiently reflect the excellent mechanical properties inherent to the CNT in the resin composite. There was a problem.
[0009]
Therefore, an object of the present invention is to provide a CNT-containing resin composite having an improved elastic modulus as compared with a matrix resin alone in order to solve the above problems.
[0010]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to produce a CNT-containing high-elastic resin composite, and as a result, selected a conjugated polymer having a strong interaction with a matrix resin having a specific chemical structure. By producing a CNT-containing resin composite by uniformly dispersing it in the matrix resin while covering the surface, it has been found that the excellent mechanical properties of CNT can be reflected in the resin composite and the elastic modulus can be improved, The present invention has been reached.
[0011]
That is, the present invention provides a resin composite in which a single-layer and / or multilayer CNT coated with a conjugated polymer is dispersed in a resin having a side chain structure, wherein the CNT has a composition fraction of 0.01% by weight with respect to the resin. A CNT-containing resin composite of not less than 1% by weight, a step of coating the CNT with a conjugated polymer, and a step of coating the CNT coated with the conjugated polymer obtained in the step with a resin having a side chain structure or the resin solution. A method for producing a CNT-containing resin composite including a step of mixing and dispersing, and a highly elastic film comprising the CNT-containing resin composite.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
The CNT-containing resin composite of the present invention and a method for producing the same will be specifically described below.
[0013]
The CNT constituting the CNT-containing resin composite of the present invention is a single-layer and / or multilayer CNT, and the CNT needs to be coated with a conjugated polymer. The conjugated polymer covering the CNT is preferably a conjugated polymer having a strong interaction with the CNT and having a strong interaction with a matrix resin having a side chain structure. Specifically, a linear conjugated polymer is preferably used as one having a strong interaction with CNT. Examples of the linear conjugated polymer include a polythiophene polymer, a polypyrrole polymer, a polyaniline polymer, a polyacetylene polymer, a polyphenylene polymer, and a polyphenylenevinylene polymer. Polythiophene-based polymers and polypyrrole-based polymers are those in which monomer units are connected at positions 2 and 5 of the thiophene ring and pyrrole ring, respectively. In polyphenylene-based polymers, poly-p-phenylene in which phenylene groups are connected in para-position The poly- or polyphenylene-vinylene-based polymer is preferably a poly-p-phenylene-vinylene-based polymer in which a phenylene group and a vinylene group are connected in the para position.
[0014]
Among the linear conjugated polymers, a polythiophene polymer is particularly preferable. Here, the polythiophene-based polymer is a polymer having a polythiophene skeleton with a side chain attached to the polymer, and is soluble in a solvent due to the effect of the side chain. Excellent workability and workability. Specific examples include poly-3-alkylthiophene (alkyl group) such as poly-3-methylthiophene, poly-3-butylthiophene, poly-3-hexylthiophene, poly-3-octylthiophene, and poly-3-dodecylthiophene. Is not particularly limited, but is preferably 1 to 12), and poly-3-alkoxythiophenes such as poly-3-methoxythiophene, poly-3-ethoxythiophene, poly-3-dodecyloxythiophene (carbon of alkoxy group) Although the number is not particularly limited, preferably 1 to 12), poly-3-alkoxy-4-alkylthiophene (alkoxy) such as poly-3-methoxy-4-methylthiophene and poly-3-dodecyloxy-4-methylthiophene The carbon number of the group and the alkyl group is not particularly limited, but is preferably 1 to 12), and poly-3 Poly-3-thioalkylthiophenes (the number of carbon atoms of the alkyl group is not particularly limited, but preferably 1 to 12) such as thiohexylthiophene and poly-3-thiododecylthiophene are preferably mentioned, and one or more kinds may be used. Can be used. Among them, poly-3-alkylthiophene and poly-3-alkoxythiophene are preferable, and as the former, poly-3-hexylthiophene is particularly preferable. The preferred molecular weight is 800 to 100,000 in terms of weight average molecular weight. The polymer does not necessarily have to have a high molecular weight, and may be an oligomer composed of a linear conjugated system.
[0015]
In the present invention, in addition to CNTs most commonly used at the present time, CNTs to which various chemical modifications are added, and CNTs in which some or all of the carbon atoms are boron (B) or nitrogen (N ) May be replaced with a BCN nanotube or a BN nanotube.
[0016]
Specific examples of the functional group introduced into the chemically modified CNT include at least one of a carboxyl group, a hydroxyl group, an amide group, an ester group, a thioester group, and a halogen group, but are not limited thereto. Absent.
[0017]
The CNT is produced by an arc discharge method, a chemical vapor deposition method (CVD method), a laser ablation method, or the like. The CNT used in the present invention may be obtained by any method. The CNT includes a single-layer CNT in which one carbon film (graphene sheet) is wound in a cylindrical shape, a two-layer CNT in which two graphene sheets are concentrically wound, and a plurality of graphene sheets. Is a multilayer CNT wound concentrically, and in the present invention, a single CNT or a plurality of CNTs can be used simultaneously.
[0018]
In the CNT-containing resin composite of the present invention, the matrix resin for dispersing the CNT needs to be a resin having a side chain structure. As the resin having a side chain structure, specifically, polystyrene, polyacrylonitrile, vinyl resins such as polyvinyl acetate and acrylic resins such as polymethyl methacrylate are preferably exemplified, and particularly polystyrene and polymethyl methacrylate are preferable. It is not limited to these, and resins other than those mentioned above, for example, a thermoplastic resin such as a nylon-based or polyester-based main chain structure, or an epoxy-based, melamine-based, or polyimide-based thermosetting resin or the like Even if a copolymer resin or the like composed of a vinyl monomer and an acrylic monomer has a side chain structure, its elastic modulus is 15% as compared with the matrix resin alone. The improved CNT-containing resin composite of the present invention can be obtained.
[0019]
Generally, when the amount of filler contained in the resin composite is increased, the elastic modulus of the resin composite increases, and the resin composite is usually used at a filler concentration of several% or more. However, in the present invention, the amount of CNT as a filler is 0.01 to 1% by weight based on the resin having a side chain structure, and the elastic modulus of the resin can be increased with a small addition amount of 1% by weight or less. Is also a feature of the present invention. By being in this range, the characteristics of the matrix resin can be utilized while the characteristics of the CNTs can be improved. When the amount of CNT is less than 0.01% by weight, the elastic modulus is not sufficiently improved, and when it exceeds 1% by weight, uniform dispersion of CNT tends to be difficult.
[0020]
When it is necessary to consider coloring properties in consideration of optical characteristics, the content is preferably 0.01 to 0.5% by weight. When it is within this range, it is difficult to visually confirm the CNT, and the transmittance of the film / film is not significantly reduced.
[0021]
Next, an example of the method for producing the CNT-containing resin composite of the present invention will be described. The CNT-containing resin composite of the present invention includes, for example, a step of coating a conjugated polymer on a CNT, and a step of coating the CNT coated with the conjugated polymer obtained in the step with a resin having a side chain structure or the resin solution. It can be manufactured through a process of mixing and dispersing.
[0022]
In the step of coating the CNT with the conjugated polymer, for example, the following method can be used. That is, (A) a method of adding and mixing CNT into a molten conjugated polymer, (B) a method of dissolving a conjugated polymer in a solvent and adding and mixing CNT therein, (C) ) A method of adding and mixing a conjugated polymer in a place where CNTs are preliminarily dispersed in a solvent by ultrasonic waves or the like; (D) putting a conjugated polymer and CNTs in a solvent, For example, a method of irradiating a sound wave and mixing. In the present invention, any of the methods may be used alone, or any of the methods may be combined. Among them, a method in which the conjugated polymer and CNT are put into the solvent (D), and the mixed system is irradiated with ultrasonic waves to be mixed.
[0023]
When the CNTs are covered with the conjugated polymer, van der Waals interactions acting between the CNTs are alleviated and the CNTs are highly dispersed in the solvent.
[0024]
Next, the step of mixing and dispersing the CNT coated with the conjugated polymer in a resin having a side chain structure or the resin solution will be described. In mixing and dispersing the CNTs coated with the conjugated polymer, (1) a method in which CNT is added to the conjugated polymer and the mixture of the conjugated polymer and CNT is used as it is; There is a method in which a mixture of the polymer and CNT is used after removing an excess conjugated polymer by filtering the CNT through a filter having a pore diameter of about 0.1 μm. Even when the latter method (2) is used for filtering, the conjugated polymer has a strong interaction with the CNT and thus covers the surface of the CNT. The fact that the conjugated polymer is coated on the surface of the CNT can be confirmed by various elemental analysis and surface analyzers.
[0025]
The procedure of mixing and dispersing includes (i) a method in which CNT covered with a conjugated polymer is redispersed in a solvent and a resin having a side chain structure is dissolved therein, and (ii) a resin solution having a side chain structure And a method in which CNT covered with a conjugated polymer is added and dispersed, and (iii) a method in which CNT is directly added to and dispersed in a resin having a liquid side chain structure. Examples of the mixing and dispersing means include stirring, ultrasonic treatment, vibration dispersion, and kneading, and it is necessary to select a means according to the concentration and viscosity. For example, as a dispersion method by stirring, a device in which a flask or a container with a lid is rotated or a screw-type or brush-type stirring blade rotates at high speed can be used. As a dispersion method by ultrasonic treatment, a container containing CNTs covered with a resin having a side chain structure and a conjugated polymer is installed in a tank of an ultrasonic cleaner, or an ultrasonic vibrator is used. There is a method such as putting it in a container for processing. As a dispersion method by kneading, a bead mill, a ball mill, a three-roller or the like using ceramic fine particles can be used. In the method for producing a CNT-containing resin composite of the present invention, it is preferable to perform ultrasonic treatment after stirring and mixing, but it is not limited thereto. By dispersing the CNT covered with the conjugated polymer in a resin having a side chain structure as a matrix resin, a CNT-containing resin composite having a conjugated polymer layer between the CNT and the matrix resin is obtained. Obtainable.
[0026]
The solvent used in the method for producing a CNT-containing resin composite of the present invention includes methanol, ethanol, butanol, toluene, xylene, o-chlorophenol, acetone, ethyl acetate, ethylene glycol, chloroform, chlorobenzene, dimethylformamide, Dimethyl sulfoxide, N-methylpyrrolidone, γ-butyrolactone, 1,1,1,3,3,3-hexafluoro-2-propanol, and the like, but are not limited thereto, and a solvent is selected as necessary. be able to.
[0027]
By processing the CNT-containing resin composite thus obtained, it can be applied to various structural materials typified by plates, functional materials such as optical resins, and composite materials with other materials such as metal materials. .
[0028]
Since the CNT-containing resin composite of the present invention has a characteristic of having high elasticity, it is possible to produce a high elasticity plastic product such as a high elasticity film and a high elasticity fiber by performing molding suitable for a resin having a side chain structure as a matrix resin. It can be used particularly preferably as a highly elastic film.
[0029]
As a specific method of film forming, for example, a CNT-containing resin composite or a resin composite solution in a fluidized state is poured into a mold or a surface to be solidified, and the CNT-containing resin composite is heated and softened using an extruder. Extrusion molding, inflation molding for extruding a molten resin composite from an annular hole to form a cylindrical film, and calender molding for rolling a CNT-containing resin composite between two heated rolls.
[0030]
Further, as a spinning method for producing fibers, there are melt spinning in which a molten resin composite is spun into a cooling chamber, dry spinning in which a liquid in which a CNT-containing resin composite is dispersed in a volatile solvent is spun into a drying chamber, Examples include wet spinning in which a liquid in which the CNT-containing resin composite is dispersed is spun into a solution containing a non-solvent, but the method of forming the CNT-containing resin composite of the present invention is not limited thereto. Films and fibers can be processed by molding in consideration of the material of the matrix resin to be used, the solubility of the resin composite, the required properties of the product, and the like.
[0031]
【Example】
Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to these examples.
[0032]
Example 1
First, 3 mg of single-walled CNT (hereinafter referred to as SWCNT) (manufactured by CNI, purity: 95%) was added to 30 mL of chloroform, and 3 mg of poly-3-hexylthiophene (manufactured by Aldrich, molecular weight: Mw 20,000) was added as a conjugated polymer. The mixture was subjected to ultrasonic agitation for 30 minutes at an output of 250 W using an ultrasonic homogenizer (VCX-500 manufactured by SONICS) while cooling with ice, to obtain a SWCNT dispersion.
[0033]
A matrix resin solution obtained by dissolving 50 mg of polymethyl methacrylate (hereinafter, referred to as PMMA) (“SUMIPEX” manufactured by Sumitomo Chemical Co., Ltd., molecular weight: Mw 500000) in 0.5 mL of chloroform is added to 0.5 mL of the obtained SWCNT dispersion liquid. Using an ultrasonic cleaner (US-2, produced by Inuchi Seieido Co., Ltd., output: 120 W, 2.6 L), a SWCNT-containing PMMA paste was obtained by ultrasonically stirring for 30 minutes.
[0034]
Next, 1 mL of the obtained paste is dropped on a 50 mm square glass substrate having a 100 μm-thick adhesive tape adhered to the periphery, and a blade coater (manufactured by RK Print-Coat Instruments, UK) is moved at a speed of 30 mm / sec. After forming a more uniform coating surface, the substrate was put into an oven at 50 ° C. for 5 minutes, and finally the solvent was removed with a vacuum dryer for 2 hours to form a 20 μm-thick coating film. A PMMA film containing 0.1% by weight was obtained.
[0035]
Next, the tensile elastic modulus of the PMMA film obtained in the same manner as above except that the PMMA film containing 0.1% by weight of the SWCNT and the SWCNT were not included was used to measure the tensile elasticity of a wide area dynamic viscoelasticity analyzer (DVE- manufactured by Rheology Co., Ltd.). V4 FT Rheospectral) in a temperature range of -20 to 100 ° C (FIG. 1). The former has a tensile modulus at 20 ° C. (E ′) of 4.21 GPa, which is very small compared to 2.25 GPa of the latter, which is a PMMA film which is a matrix resin, despite the very small content of SWCNT. 87%.
[0036]
Example 2
A matrix resin solution in which 50 mg of polystyrene (manufactured by Wako Pure Chemical Industries, Ltd., degree of polymerization: about 3000) was dissolved in 4.5 mL of chloroform was added to 0.5 mL of the same SWCNT dispersion liquid as in Example 1, and the same as in Example 1 was added. Ultrasonic stirring was performed for 30 minutes using an ultrasonic washer to obtain a SWCNT-containing polystyrene paste. Using the paste, a coating film having a thickness of 10 μm was prepared in the same manner as described above.
[0037]
When the tensile elastic modulus at 20 ° C. of the polystyrene film obtained in the same manner as described above except that the polystyrene film containing 0.1% by weight of SWCNT and the SWCNT were not contained was measured in the same manner as in Example 1, the tensile strength of the former was measured. The modulus of elasticity is 3.16 GPa, and despite the fact that the content of SWCNT is extremely low, the tensile modulus (E ') at 20 ° C. of the latter matrix resin, polystyrene film, is 32 compared with 2.39 GPa. % Increased.
[0038]
Example 3
First, 50 mg of SWCNT is put into 200 mL of a mixed acid having a 3: 1 volume ratio of sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd., purity: 95% or more) and nitric acid (manufactured by Wako Pure Chemical Industries, Ltd., density: 1.38). After ultrasonically stirring using an ultrasonic cleaner for 10 hours, the mixture of the mixed acid and SWCNT was filtered through a polytetrafluoroethylene (PTFE) membrane filter (manufactured by Millipore Corporation, filter type: JH) to remove carboxyl groups. The introduced SWCNT (hereinafter referred to as c-SWCNT) was filtered off.
[0039]
Using 3 mg of the obtained c-SWCNT and 3 mg of poly-3-hexylthiophene as a conjugated polymer in the same manner as in Example 1, a dispersion was prepared using 30 mL of chloroform as a solvent. A matrix resin solution obtained by dissolving 50 mg of PMMA in 4.5 mL of chloroform was added to 0.5 mL of the dispersion, and the mixture was ultrasonically stirred for 30 minutes using the same ultrasonic cleaner as in Example 1 to obtain a PMMA paste containing c-SWCNT. Thus, a PMMA film containing 0.1% by weight of c-SWCNT was obtained in the same manner as in Example 1.
[0040]
When the tensile modulus at 20 ° C. of the PMMA film containing 0.1% by weight of c-SWCNT was measured in the same manner as in Example 1, it was 3.65 GPa, and the tensile modulus at 20 ° C. of the PMMA film as a matrix resin ( E ') It increased by 62% compared to 2.25 GPa.
[0041]
Comparative Example 1
A PMMA film containing 0.1% by weight of SWCNT was obtained in the same manner as in Example 1 except that the conjugated polymer was not used. The tensile modulus of this film was measured with a wide range dynamic viscoelasticity measuring device in the same manner as in Example 1. The tensile modulus at 20 ° C. was 2.44 GPa, which was almost the same as that of the PMMA film as a matrix resin. Met.
[0042]
Comparative Example 2
A 6-nylon film containing 0.1% by weight of SWCNT was obtained in the same manner as in Example 1 except that 6-nylon, a resin having no side chain structure, was used as the matrix resin. The tensile elastic modulus of this film was measured with a wide-range dynamic viscoelasticity measuring device in the same manner as in Example 1. The tensile elastic modulus at 20 ° C. was 2.40 GPa, and was the same as the above method except that SWCNT was not included. The modulus of elasticity of the obtained 6-nylon film increased only about 5.7% from 2.27 GPa.
[0043]
【The invention's effect】
According to the present invention, by dispersing the CNT coated with the conjugated polymer in a specific matrix resin, both the CNT and the matrix resin are strongly bound via the conjugated polymer without going through complicated steps. Since the CNTs can be uniformly dispersed in the matrix resin, even with a small amount of CNT added, the properties of the CNTs can be effectively exhibited, and the elastic modulus of the resin composite can be dramatically improved. Further, a highly elastic film can be obtained from the resin composite.
[Brief description of the drawings]
FIG. 1 is a graph showing the temperature characteristics of the tensile modulus of each PMMA film obtained in Example 1.

Claims (11)

A resin composite in which single-walled and / or multi-walled carbon nanotubes coated with a conjugated polymer are dispersed in a resin having a side chain structure, wherein a composition ratio of the carbon nanotubes to the resin is 0.01% by weight or more, A carbon nanotube-containing resin composite having a content of 1% by weight or less. 2. The carbon nanotube-containing resin composite according to claim 1, wherein the conjugated polymer is a linear conjugated polymer. The carbon nanotube-containing resin composite according to claim 2, wherein the linear conjugated polymer is a polythiophene polymer. The carbon nanotube-containing resin composite according to claim 3, wherein the polythiophene-based polymer is at least one of poly-3-alkylthiophene, poly-3-alkoxythiophene, and poly-3-thioalkylthiophene. The carbon nanotube-containing resin composite according to claim 1, wherein the resin having a side chain structure is at least one of a vinyl resin and an acrylic resin. The carbon nanotube-containing resin composite according to claim 5, wherein the vinyl resin is polystyrene. The carbon nanotube-containing resin composite according to claim 5, wherein the acrylic resin is polymethyl methacrylate. The carbon nanotube-containing resin composite according to claim 1, wherein a functional group is introduced into the carbon nanotube. The carbon nanotube-containing resin composite according to claim 8, wherein the functional group is at least one of a carboxyl group, a hydroxyl group, an amide group, an ester group, a thioester group, and a halogen group. A step of coating the conjugated polymer on the carbon nanotubes, and a step of mixing and dispersing the carbon nanotubes coated with the conjugated polymer obtained in the step in a resin having a side chain structure or the resin solution. Composite manufacturing method. A highly elastic film comprising the carbon nanotube-containing resin composite according to claim 1.

Images