JP5820576B2 - Manufacturing method of composite material - Google Patents

Description

  The present invention relates to a method for manufacturing a composite material.

  A composite material of a polymer and an inorganic compound is attracting attention as a material having both properties such as processability and toughness of the polymer and heat resistance and hardness of the inorganic compound. Among inorganic compounds, layered clay minerals have been studied in various ways to be combined with polymers because of their unique properties (dispersibility in water, ion exchange capacity, etc.). For example, an intercalation method (for example, see Patent Document 1) in which an organic ammonium salt is inserted between layers of a layered clay mineral to improve the affinity with a polymer to form a composite, and a polymerizable monomer is interposed between layers of a layered clay mineral. An in-situ method (for example, refer to Patent Document 2) in which a monomer is polymerized after insertion is used.

  However, the above-mentioned intercalation method has a problem in terms of cost because treatment with an organic ammonium salt (ion exchange, filtration, washing, etc.) requires time and the organic ammonium salt is expensive. Moreover, since a low molecular weight compound exists in the obtained composite material, it is difficult to obtain a desired composition, and characteristics such as heat resistance and mechanical performance may be deteriorated. On the other hand, in the in-situ method, depending on the monomer used, there is a problem that the layered clay mineral requires a pretreatment such as acid treatment or an expensive catalyst. Therefore, it is desired to produce a composite material by a simple operation.

JP 2000-336241 A Japanese Patent Laid-Open No. 11-236501

  This invention is made | formed in view of this situation, The main objective is to provide the method which can manufacture a composite material by simple operation.

The method for producing a composite material of the present invention comprises a step of preparing a mixed solution by mixing a polymer solution and a dispersion in which a layered clay mineral is dispersed, and a step of reducing the solubility of the polymer in the mixed solution. In order.
In preferable embodiment, the solubility of a polymer is reduced by cooling the said liquid mixture.
In a preferred embodiment, the solubility of the polymer is lowered by adding a poor solvent for the polymer to the mixed solution.
In preferable embodiment, the mixture ratio of the said layered clay mineral is 0.5 weight part-150 weight part with respect to 100 weight part of polymers.
According to another aspect of the invention, a composite material is provided. This composite material is obtained by the above manufacturing method.
In a preferred embodiment, the layered clay mineral, which has been exfoliated by laminating layered molecules, has a configuration in which it is coated with a polymer.

  According to the present invention, a composite material can be produced by a simple operation without requiring a treatment agent such as an organic ammonium salt. Moreover, according to the present invention, a composite material can be produced satisfactorily even when the blending ratio of the layered clay mineral is increased.

It is a XRD measurement result of the composite material obtained in the Example of this invention. It is a XRD measurement result of the composite material obtained in the Example of this invention.

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.

A. Manufacturing Method The manufacturing method of the composite material of the present invention includes a step of preparing a mixed solution by mixing a polymer solution and a dispersion in which a layered clay mineral is dispersed (step 1), and reducing the solubility of the polymer in the mixed solution. Step (step 2) to be performed in this order.

A-1. Process 1
The polymer solution is typically prepared by dissolving the polymer in a solvent. Any appropriate polymer can be selected as the polymer depending on the desired composite material. For example, polycarbonate polymer; polyester polymer such as polylactic acid and polyethylene terephthalate; polysulfone polymer such as polyethersulfone; olefin polymer such as polyethylene and polypropylene; cycloolefin polymer; polyvinyl alcohol polymer; polyimide polymer; Aromatic polyether ketone polymers such as ether ether ketone; and copolymers thereof (for example, ethylene-vinyl alcohol copolymer). These can be used alone or in combination of two or more.

  As a solvent for the polymer solution, any appropriate solvent can be selected depending on the polymer to be used. For example, amides such as formamide, N-methylformamide, N, N-dimethylformamide, N, N-dimethylacetamide, alcohols such as methanol, ethanol and 2-propanol, glycols such as ethylene glycol, N-methylpyrrolidone , Sulfolane, dimethyl sulfoxide, tetrahydrofuran, dioxane, water and the like. These can be used alone or in combination of two or more. Preferably, a solvent capable of dispersing a layered clay mineral described later is used. By using such a solvent, the polymer can be satisfactorily adsorbed on the surface of the layered clay mineral and deposited in the step 2 described later. Examples of such a solvent include N-methylformamide, formamide, and a mixed solvent of formamide and N-methylpyrrolidone, ethanol, methanol, N, N-dimethylformamide, N, N-dimethylacetamide, ethylene glycol, and the like. It is done.

  The concentration of the polymer solution is preferably 1% by weight to 30% by weight, and more preferably 5% by weight to 15% by weight.

  The temperature of the polymer solution (at the time of preparing the mixed solution) is set according to, for example, the polymer to be used and the solvent of the polymer solution. Typically, it is 50 ° C to 150 ° C, preferably 90 ° C to 120 ° C. By setting to such temperature, it can prevent that a polymer precipitates at the time of liquid mixture preparation.

  Any appropriate layered clay mineral can be adopted as the layered clay mineral. For example, mica, vermiculite, montmorillonite, beidellite, saponite, hectorite, stevensite, magadayite, isralite, kanemite, illite, sericite and the like can be mentioned. These can be used alone or in combination of two or more. Preferably, mica, montmorillonite, saponite or the like is used.

  The shape of the layered clay mineral is not particularly limited, but preferably the average length is 10 nm to 50 μm, the thickness is 1 nm to 100 nm, and the aspect ratio is 10 to 50000.

  Examples of the dispersion medium for the layered clay mineral include, for example, formamide, N-methylformamide, N, N-dimethylformamide, amides such as N, N-dimethylacetamide, glycols such as ethylene glycol, water, sulfolane, dimethyl sulfoxide, Tetrahydrofuran etc. are mentioned. These can be used alone or in combination of two or more. Preferably, the layered clay mineral dispersion medium is selected in consideration of the solubility of the polymer used. This is to prevent the polymer from precipitating during the preparation of the mixed solution.

  In general, the layered clay mineral can be sufficiently dispersed by stirring, but if necessary, mechanical shearing force may be applied by a homogenizer or the like.

  The amount of the layered clay mineral is preferably 0.1 to 25 parts by weight, more preferably 1 to 10 parts by weight with respect to 100 parts by weight of the dispersion medium.

  The temperature of the layered clay mineral dispersion (at the time of preparing the mixture) is set, for example, according to the polymer to be used and the solvent of the polymer solution. Typically, it is room temperature to 150 ° C. By setting to such temperature, it can prevent that a polymer precipitates at the time of liquid mixture preparation.

  The mixed solution is prepared by mixing a polymer solution and a dispersion of a layered clay mineral. Here, it is preferable to mix while heating. The heating temperature is typically 50 ° C to 150 ° C, preferably 90 ° C to 120 ° C. The blend of the polymer solution and the dispersion of the layered clay mineral can be set to any appropriate ratio depending on the desired composite material. The blending ratio of the layered clay mineral (solid content) is preferably 0.5 to 150 parts by weight, more preferably 25 to 100 parts by weight with respect to 100 parts by weight of the polymer (solid content). According to the production method of the present invention, a composite material can be produced satisfactorily even when the blending ratio of the layered clay mineral is increased.

A-2. Process 2
Next, the solubility of the polymer in the mixed solution prepared in step 1 is lowered. By reducing the solubility of the polymer in the mixed liquid in which the layered clay mineral is dispersed, the polymer can be adsorbed and deposited on the surface of the layered clay mineral in order to stabilize thermodynamically, thereby producing a composite material. . Thus, the composite material can be manufactured by a simple operation.

  In one embodiment, the solubility of the polymer is reduced by cooling the mixture. The cooling temperature is set according to, for example, the polymer and the solvent of the polymer solution. The cooling temperature is preferably −10 ° C. to 50 ° C., more preferably 10 ° C. to 30 ° C.

  In another embodiment, the solubility of the polymer is reduced by adding a polymer poor solvent to the mixture. Preferably, the poor solvent has an absolute value of 10 or more of a difference between the relative dielectric constant of the poor solvent and the relative dielectric constant of the solvent of the polymer solution. By using a poor solvent satisfying such a relationship, a composite material can be manufactured satisfactorily. For example, when ethylene-vinyl alcohol copolymer is used as the polymer and N, N-dimethylacetamide is used as the solvent of the polymer solution, acetone, water, ethanol, isopropanol, etc. are preferably used as the poor solvent.

B. According to the production method of the present invention, even when the blending ratio of the layered clay mineral is increased, the polymer and the layered clay mineral can be favorably combined (for example, down to the nano level). As a result, the resulting composite material can have excellent properties. Specifically, characteristics such as heat resistance and gas barrier properties of the molded product can be greatly improved. In addition, the composite material obtained is excellent in molding processability even when the blending ratio of the layered clay mineral is high, so that it can be adjusted to a desired concentration by melt mixing with the polymer constituting the composite material. In addition, it can be melt-mixed with other polymers for the purpose of obtaining the desired performance. Thus, it can be used as a master batch.

  In a preferred embodiment, the composite material obtained according to the present invention has a structure in which the above lamellar clay mineral that has been separated into lamellar layers (single layer) is coated with a polymer. Such a composite material can be diluted and dispersed in a poor solvent for a polymer such as ethanol, methanol, and acetone. For example, after the dispersion is cast, it can be observed with a scanning electron microscope (SEM) that the layered clay mineral covered with the polymer is in a peeled state (in the form of flakes). Further, by conducting elemental analysis by energy dispersive X-ray spectroscopy (EDS), the presence of polymer-derived elements such as carbon and nitrogen can be confirmed on the flakes (single layer) of the exfoliated layered clay mineral.

  For example, it becomes possible to form a composite material layer in which layered clay minerals coated are cast by casting a dispersion liquid in which the composite material is dispersed, and a dense composite material by applying a post-treatment such as heat press. Layer formation is also possible. In addition, even when such a composite material is melt-molded, the layered clay mineral can exist in a state where a single layer is peeled off, and a nano-level composite material can be easily produced.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. The details of the measurement method are as follows.

[Example 1]
(Process A)
As the polymer, an ethylene-vinyl alcohol copolymer (EVOH) (trade name: EVAL L171A, manufactured by Kuraray Co., Ltd.) having an ethylene copolymerization ratio of 27 mol% was used. While heating dimethylacetamide (relative dielectric constant: 37.8) to 160 ° C., EVOH was dissolved to prepare a 10 wt% polymer solution.
Further, Kunipia F (Kunimine Kogyo Co., Ltd.) was added as a layered clay mineral to formamide (relative dielectric constant: 109) and subjected to a dispersion treatment with a homogenizer to prepare a 5% by weight layered clay mineral dispersion.
Thereafter, 34.2 g of the layered clay mineral dispersion kept at room temperature was slowly dropped into 40 g of the polymer solution kept at 120 ° C., and the mixture was stirred while heating to 120 ° C. to prepare a mixed solution.

(Process B)
The resulting mixture was allowed to cool at room temperature. The precipitate produced by cooling was filtered, washed with methanol, and then dried to obtain a composite material.

[Example 2]
(Process A)
A mixed solution was prepared in the same manner as in Example 1.

(Process B)
72.2 g of the obtained mixed liquid was heated to 80 ° C. and 100 g of isopropanol (relative dielectric constant: 19.9) was slowly added dropwise with stirring to produce a white precipitate. The resulting precipitate was collected in the same manner as in Example 1 to obtain a composite material.

[Example 3]
(Process A)
Polyethersulfone (manufactured by Sumitomo Chemical Co., Ltd., trade name: PES5003P) was used as the polymer. While heating dimethylformamide to 160 ° C., PES5003P was dissolved to prepare a 10 wt% polymer solution.
Further, Kunipia F (Kunimine Kogyo Co., Ltd.) was added as a layered clay mineral to N-methylformamide and dispersed with a homogenizer to prepare a layered clay mineral dispersion having a weight of 6%.
Thereafter, 16.7 g of a dispersion of a layered clay mineral kept at room temperature was slowly dropped into 20.0 g of the polymer solution kept at 120 ° C., and stirred while heating to 120 ° C. to prepare a mixed solution.

(Process B)
The resulting mixture was allowed to cool at room temperature. Methanol was added to the white turbid dispersion by cooling to precipitate the precipitate, which was filtered, washed with methanol, and dried to obtain a composite material.

The following measurements were performed on the composite materials obtained in each example.
1. XRD Measurement The obtained composite material was dried at 80 ° C. for 3 hours, and then molded into a sheet (thickness: 500 μm) by a hot press (manufactured by Tester Sangyo Co., Ltd.) to prepare a measurement sample. Here, Example 1 and Example 2 were formed into sheets under molding conditions of 220 ° C. and 0.5 MPa. Example 3 was formed into a sheet under molding conditions of 350 ° C. and 0.5 MPa.
X-ray diffraction measurement of the obtained measurement sample was performed in the range of 2θ = 1 to 12 ° with an X-ray diffractometer (RINT-Utima3, manufactured by Rigaku Corporation).
2. TG-DTA measurement The layered clay mineral content in the obtained composite material was measured with TG-DTA (manufactured by Shimadzu Corporation). The measurement is carried out with air flow (0.5 L / min), and the temperature is increased from 30 ° C. to 1000 ° C. at a rate of 10 ° C./min, and the layered clay mineral present in the composite material from the weight reduction rate at that time The content of was calculated.

  The result of the XRD measurement is shown in FIG. No peak (around 2θ = 8 °) due to the layered clay mineral (Kunipia F) is observed, the polymer is adsorbed on the surface of the layered clay mineral, inserted between the layers, and the layered molecules peel off to form a flake (single layer) Therefore, it is considered that it was compounded. Moreover, when the content of the layered clay mineral in the obtained composite material was confirmed by thermal analysis, it was confirmed that 30% by weight of the layered clay mineral was contained.

[Example 4]
(Use as a master batch)
Laboplast 2.24 g of the composite material obtained in Example 1 and 11.19 g of ethylene-vinyl alcohol copolymer (EVOH) (trade name: EVAL L171A, manufactured by Kuraray Co., Ltd.) having an ethylene copolymerization ratio of 27 mol% The mixture was mixed in a mill (manufactured by Toyo Seiki Co., Ltd.) at 220 ° C. and 90 rpm. The obtained mixture was molded into a 500 μm sheet by hot pressing under conditions of 220 ° C. and 0.5 MPa.

  The obtained sheet was transparent and no aggregate was confirmed. The layered clay mineral content of the obtained sheet was calculated by thermal analysis and found to be 4.8% by weight.

  The results of XRD measurement of Example 1 and Example 4 are shown in FIG. In Example 1, a clear peak was confirmed around 2θ = 7 ° due to the insertion of the polymer between the layers, whereas in Example 4, the peak intensity was greatly reduced, and the peak was at a low angle. It is shifting to the side. This suggests that in Example 4, it is dispersed at the nano level due to further progress of exfoliation of the layered clay mineral. Therefore, it can be said that the layered clay mineral content can be easily adjusted by using the composite material obtained by the present invention as a master batch.

  According to the present invention, a composite material excellent in mechanical strength and gas barrier properties can be easily produced. In addition, in the composite material with super engineering plastic, the surface treatment of the molded product can be omitted, and not only the mechanical properties are improved but also the wear resistance and sliding property are greatly improved compared with the existing composite material process. Improvements are also possible. Therefore, the composite material obtained by the present invention can be used for, for example, food packaging films, packaging packages for electronic materials, fields where gas barrier properties are required such as display members, machines such as copiers, printers, VTRs, cameras, automobiles, etc. It can be suitably used for sliding members such as parts (for example, gears, bearings, etc.).

Claims (4)

N-methylformamide, formamide, or at least one solvent selected from the group consisting of formamide and N-methylpyrrolidone, ethanol, methanol, N, N-dimethylformamide, N, N-dimethylacetamide, and ethylene glycol A step of preparing a mixed solution by mixing a polymer solution containing a mixed solvent and a dispersion in which a layered clay mineral is dispersed;
Reducing the solubility of the polymer in the mixed solution in this order.   The manufacturing method of the composite material of Claim 1 which reduces the solubility of a polymer by cooling the said liquid mixture.   The method for producing a composite material according to claim 1, wherein the solubility of the polymer is reduced by adding a poor solvent for the polymer to the mixed solution. The manufacturing method of the composite material in any one of Claim 1 to 3 whose compounding ratio of the said layered clay mineral is 0.5 weight part-150 weight part with respect to 100 weight part of polymers.