JP6432082B2 - Method for producing polyolefins with excellent functions - Google Patents

Description

  Polyolefin is a very good general-purpose plastic material that combines low cost, light weight, high melting point, easy moldability, wide mechanical properties, and good recyclability. Polyolefins also have an environmental protection advantage because they do not generate harmful gases during combustion. Among them, polypropylene has a high melting point and high strength, and its performance is further improved by various methods. For this reason, in recent years, there has been a strong movement to replace inorganic materials and engineer plastics with polyolefins such as polypropylene. Among these alternative methods, composites of inorganic materials (so-called fillers) and polyolefins are commonly used means for mechanical reinforcement and functionalization of polyolefins.

  The composite of filler and polyolefin is usually performed by a composite manufacturer by melt-kneading polyolefin pellets and filler supplied from a resin manufacturer. However, it is not easy to disperse the filler in polyolefin with poor polarity. Until now, various devices such as addition of a compatibilizing agent and chemical modification of the filler surface have been devised to improve dispersibility.

  In particular, magnesium hydroxide as a flame retardant achieves a flame resistance that can withstand practical use by blending with a relatively large amount of polyolefin, usually about 60% by weight of the polyolefin. In this case, the problem that magnesium hydroxide does not disperse well in the polyolefin is serious. For this reason, various things are proposed as a dispersibility improvement method with respect to polyolefin of magnesium hydroxide particles.

JP 2008-75052 A JP 2010-174120 A JP 2009-522205 A Patent Document 1 describes that magnesium hydroxide previously surface-treated with pentaerythritol and zinc stearate is blended with polyolefin. Patent Document 2 describes that a porous body obtained from particles containing alkoxysilane and magnesium hydroxide is used as a flame retardant. Patent Document 3 describes that the surface of magnesium hydroxide nanoparticles that has been surface-treated with an organic dispersant is dispersed in a polymer.

  However, the conventional methods as described in Patent Documents 1, 2, and 3 require a surface treatment agent, an alkoxysilane, and an organic dispersant that function as a dispersibility improver for magnesium hydroxide. The influence which a property improvement agent has on the polypropylene composition finally obtained is unavoidable. Usually, in polypropylene for industrial products, in addition to flame retardants, other additives such as deterioration inhibitors and colorants are added at the same time, so by the interaction between these dispersibility improvers and other additives, There exists a possibility that the modification effect by other additives may be impaired. In addition, there is a concern about a phenomenon in which these dispersibility improvers are precipitated on the surface of the molded body after molding the material, so-called bleeding phenomenon.

  The above-described problems relating to flame retardancy of polypropylene are the same in flame retardancy of other polyolefins such as polyethylene. The technique of uniformly dispersing a metal hydroxide such as magnesium hydroxide in a polyolefin without the intervention of a dispersibility improver, which is an extra component, to obtain a polyolefin composition having sufficient flame retardancy for industrial product use is as follows. It has not been proposed yet.

  Therefore, current methods for dispersing inorganic fillers in polyolefin often result in disadvantageous side effects such as increased cost, accelerated degradation, and bleed out. The problem in such dispersion is caused by “trying to mix two bulk bodies, polyolefin and inorganic filler, which are difficult to mix thermodynamically, against high viscosity” and cannot be avoided technically. Has been considered.

  However, it is essential to add an inorganic filler in order to increase the added value of the polyolefin. Solving the above problems when dispersing inorganic fillers has been considered difficult in the past, but is a goal that one skilled in the art cannot give up in improving polyolefin materials. Improving the dispersibility of inorganic fillers in polyolefins while avoiding the disadvantageous side effects associated with the prior art is awaited as an innovative improvement technique in polyolefin materials and their application fields.

  Accordingly, the inventor has sought a completely new approach that is not confined to the conventional methods in order to achieve good dispersion of the inorganic filler in the polyolefin, and has attempted to solve the above problems.

  As a result, the inventors have found that a method using a sol-gel reaction is effective. The inventor first discovered an epoch-making method of converting a metal alkoxide into an inorganic filler such as a metal oxide or metal hydroxide after impregnating a polyolefin with a solution of a metal alkoxide as a precursor of an inorganic filler. It was. By this method, a nanocomposite in which nanosized inorganic fillers are highly dispersed in a polyolefin matrix can be produced without using a compatibilizing agent or surface chemical modification.

That is, the present invention is as follows.
(Invention 1) A method for producing a highly functional nanocomposite in which an inorganic filler is dispersed in a polyolefin, comprising the following steps.
(Step 1) A step of polymerizing olefins in a polymerization vessel.
(Step 2) A step of mixing the polyolefin reactor powder obtained in Step 1 with a solution of a metal alkoxide, which is a precursor of an inorganic filler, and impregnating the polyolefin powder with a metal alkoxide.
(Step 3) A step of drying the polyolefin powder obtained in Step 2 to remove the solvent.
(Step 4) A step of transferring the polyolefin powder obtained in Step 3 to a humid atmosphere.
(Step 5) A step of completing a sol-gel reaction by melting and kneading polyolefin powder simultaneously with step 4 or subsequent to step 4 to obtain a highly functional nanocomposite.
(Invention 2) The method for producing a highly functional nanocomposite according to Invention 1, wherein the inorganic filler is a metal oxide or a metal hydroxide.
(Invention 3) The highly functional nano of Invention 1 or 2, wherein the inorganic filler is at least one selected from TiO ₂ , SiO ₂ , ZnO, MgO, Mg (OH) ₂ , Al ₂ O ₃ , Al (OH) ₃ Composite manufacturing method.
(Invention 4) The method for producing a highly functional nanocomposite of Inventions 1 to 3, wherein the highly functional nanocomposite is for a masterbatch.
(Invention 5) A highly functional masterbatch comprising a highly functional nanocomposite obtained by the production method of Invention 4.

Each step of the present invention will be described in detail below. FIG. 1 schematically shows an example of the production method of the present invention.
(Process 1)
This is a process for producing a polyolefin by polymerizing olefins in a polymerization vessel. There is no restriction | limiting in an olefin polymerization method. Typical olefins are ethylene and α-olefins having 3 to 10 carbon atoms. As selection of the monomer, ethylene alone, ethylene and propylene, propylene alone, propylene and α-olefin having 4 to 10 carbon atoms are generally used. Small amounts of branched olefins, aromatic olefins and dienes can be used. A step of producing polyethylene using ethylene as a main monomer and a step of producing polypropylene using propylene as a main monomer are preferred. As a method for producing polyethylene, a high pressure polymerization method, a Ziegler-Natta method, a Phillips method, and a Metallocene method are generally used. As a method for producing polypropylene, the Ziegler-Natta method and the Metallocene method are generally used. The radical initiator, Ziegler-Natta catalyst, Phillips catalyst, and Metallocene catalyst used in these polymerization methods are not limited. The polyolefin powder produced in step 1 is taken out from the polymerization reactor (reactor) and then directly conveyed to step 2.

(Process 2)
In this step, the polyolefin reactor powder obtained in step 1 is mixed with a solution of a metal alkoxide, which is a precursor of an inorganic filler, to impregnate the reactor powder with the metal alkoxide. The inorganic filler used in this step is not limited as long as it is a metal oxide or metal hydroxide having a modifying effect on polyolefin. TiO ₂ , SiO ₂ , ZnO, MgO, Mg (OH) ₂ , Al ₂ O ₃ , Al (OH) ₃ can be used as the metal oxide or metal hydroxide. Ti, Si, Zn, Mg, Al alkoxides are used as precursors. Among such metal alkoxides, the formula M (OR) _n (M is a metal atom. R is an alkyl group having 2 to 6 carbon atoms. N is an integer corresponding to the valence of the metal atom) is preferable.

When the metal alkoxide is solid at room temperature, a solution obtained by dissolving the metal alkoxide in a solvent having high affinity for polyolefin is used as the metal alkoxide solution. Examples of such a solvent include at least one selected from alcohols such as methanol and ethanol, aromatics such as toluene, xylene and benzene, ketones such as acetone and diethyl ketone, and chlorinated solvents such as dichloromethane. Can be used. When the metal alkoxide is liquid at room temperature, the metal alkoxide solution or a solution composed of the metal alkoxide and the above solvent can be used as the metal alkoxide solution. For example, titanium alkoxides such as Ti (OEt) ₄ , Ti (OnPr) ₄ , Ti (OiPr) ₄ , Ti (OnBu) ₄ , and Ti (OiBu) ₄ that are precursors of TiO ₂ are used as they are, or Dilute to an appropriate concentration with the above solvent.

  The concentration of the metal alkoxide contained in the metal alkoxide solution can be appropriately set according to the saturation concentration of the metal alkoxide in the solvent. The amount of the metal alkoxide with respect to the reactor powder can be appropriately set according to the concentration of the inorganic filler finally dispersed in the polyolefin. When the resulting high-performance nanocomposite is used as a masterbatch, a relatively high concentration metal alkoxide solution is mixed with the reactor powder in order to impregnate a relatively high concentration metal alkoxide.

  The method for mixing the reactor powder and the metal alkoxide solution is not limited as long as the reactor powder and the metal alkoxide solution are uniformly mixed. Various mixers can be used as a mixing device. Mixing is performed at a temperature below the softening point of the polyolefin.

  In step 2, it is preferable to add an antioxidant to prevent thermal degradation of the polyolefin in step 5. As the antioxidant, those known as antioxidants for polyolefins can be used. For example, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -1,3,5-triazine-2,4,6 (1H, 3H, 5H) -trione, 4 , 4 ', 4' '-(1-Methylpropanyl-3-ylidene) tris (6-t-butyl-m-cresol), 6,6'-di-t-butyl-4,4'-butylidene- m-cresol, octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 3,9-bis {2- [3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy] -1,1-dimethylethyl} -2,4,8,10-tetraoxaspiro [5.5] Use phenolic antioxidants such as undecane, 1,3,5-t tris (3,5-di-t-butyl-4-hydroxyphenylmethyl) -2,4,6-trimethylbenzene Can do.

  In step 2, a sol-gel reaction accelerator can be used in combination with the metal alkoxide solution as necessary. Such accelerators include bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) butane-1,2 , 3,4-tetracarboxylate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) butane-1,2,3,4-tetracarboxylate, bis (2,2,6,6- Tetramethyl-4-piperidyl) sebacate, bis (1-undecanoxy-2,2,6,6-tetramethylpiperidin-4-yl) carboxylate, 1,2,2,6,6-pentamethyl-4-piperidyl Basic compounds such as methacrylate and 2,2,6,6-tetramethyl-4-piperidyl methacrylate, and acidic compounds such as citric acid and maleic acid-modified polyolefin can be used. Of these, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and tetrakis (2,2,6,6-tetramethyl-4-piperidyl) butane-1 which are highly compatible with polyolefin 1,2,3,4-tetracarboxylate, citric acid and maleic acid are preferred.

(Process 3)
In this step, the polyolefin powder obtained in step 2 is dried to remove the solvent. There is no restriction on the drying method. For example, vacuum drying, freeze drying, and airflow drying can be used. As a result of the removal of the solvent, a powder in which the polyolefin is impregnated with metal alkoxide molecules is obtained.

(Process 4)
In this step, the polyolefin powder obtained in step 3 is transferred to a humid atmosphere. Process 4 and process 5 described later are performed simultaneously, or process 4 described below is performed subsequent to process 4. When the metal alkoxide impregnated in the polyolefin is converted into a metal hydroxide under the conditions of melt kneading in Step 5 described later to complete the sol-gel reaction, for example, the magnesium alkoxide is converted into magnesium hydroxide and the sol-gel reaction Is completed, sufficient water is supplied to the metal alkoxide in step 4. In such a case, in step 4, it is necessary to hydrate the metal alkoxide molecule by atmospheric exposure with sufficient time, water vapor spraying, or the like. As such a hydration treatment method, steam spray with a short treatment time is preferable. When the metal alkoxide impregnated in the polyolefin is converted into a metal oxide under the conditions of melt kneading in Step 5 described later, the sol-gel reaction is completed. For example, the aluminum alkoxide is converted into aluminum oxide and the sol-gel reaction is completed. When the sol-gel reaction is completed by converting titanium alkoxide into titanium oxide, the transition to a wet atmosphere is carried after the step 3 by transporting the polyolefin powder to the facility for performing step 5 in the air atmosphere. The operation to do is enough.

(Process 5)
In this step, the polyolefin powder obtained in Step 4 is melt-kneaded. The sol-gel reaction proceeds under the melt-kneading conditions in Step 5, and the metal alkoxide impregnated in the polyolefin matrix is converted into nano-sized metal hydroxide or metal oxide. As a result of the completion of the sol-gel reaction, a highly functional nanocomposite in which nanosized inorganic fillers are dispersed in polyolefin is obtained. The melt kneading temperature is not less than the melting temperature of the polyolefin and not more than the temperature at which the thermal degradation of the polyolefin is minimized. When polyethylene is used, the temperature is generally 120 to 150 ° C. When polypropylene is used, the temperature is generally 160 to 200 ° C. There is no restriction | limiting in the apparatus used for melt-kneading. Various mixers and extruders can be used. Thus, from the polymerization of olefins to the production of high-functional composites containing polyolefin and inorganic filler can be performed in an integrated process.

  The complete conversion of the metal alkoxide into the metal oxide or metal hydroxide can be confirmed by measuring the infrared (IR) absorption spectrum of the high-performance nanocomposite. In the IR absorption spectrum of the highly functional nanocomposite produced by the integrated process including Step 1 to Step 5 described above, no absorption peak derived from M—O—C (M: metal atom) of the metal alkoxide is detected. Absorption peaks derived from oxides or metal hydroxides are detected.

  It can be confirmed with a transmission electron microscope (TEM) image of the highly functional nanocomposite that the nano-sized inorganic filler is uniformly dispersed in the polyolefin. In the highly functional nanocomposite obtained by the production method of the present invention, it is observed that the inorganic fillers are not aggregated and are uniformly dispersed in the polyolefin as nano-sized primary particles.

  In step 5, additives such as a highly functional nanocomposite containing different inorganic fillers, inorganic fillers, colorants, antioxidants, processability improvers, and the like can also be mixed. The added inorganic filler may be another metal oxide or metal hydroxide that does not correspond to the metal alkoxide used so far. As a result, a wide variety of highly functional nanocomposites can be produced. In step 5, the high-performance nanocomposite can be pelletized following the melt-kneading. The obtained pellets can be stored and transported as a molding material or as a master batch. Further, following the step 5, the high-functional nanocomposite can be extruded and injection molded.

When the inorganic filler is TiO ₂ , the highly functional nanocomposite in which nano-sized TiO ₂ is uniformly dispersed has both a high ultraviolet shielding function and a high visible light transmittance. Such highly functional nanocomposites are effective as UV-cut film materials for building materials and electrical equipment.

  When the inorganic filler is ZnO, the high-performance nanocomposite in which nano-sized ZnO is uniformly dispersed suppresses the decrease in mechanical strength as seen in conventional inorganic filler-containing polyolefins, and is excellent in conductivity. Such a high-performance nanocomposite is expected as an inexpensive material that replaces the current material for parts that require electrical conductivity.

When the inorganic filler is Mg (OH) ₂ , nano-sized Mg (OH) ₂ is uniformly dispersed, so that a higher flame retardancy improvement effect can be obtained with a smaller amount of Mg (OH) ₂ than conventional. . In the resulting high-performance nanocomposite, the reduction in mechanical strength, which has been a problem in the past, is suppressed. Such highly functional nanocomposites are highly valuable as improved products of conventional flame retardant polyolefins. The same applies when the inorganic filler is Al (OH) ₃ .

When the inorganic filler is Al ₂ O ₃ , a highly functional nanocomposite in which nano-sized Al ₂ O ₃ is uniformly dispersed exhibits significantly high thermal conductivity. Such highly functional nanocomposites can be expected as an alternative to conventional heat conductive resin materials.

  The highly functional nanocomposite obtained in the present invention can also be used as a masterbatch containing a high concentration of inorganic filler. By diluting the highly functional nanocomposite for the masterbatch with other resin materials singly or in combination, various new materials in which the functions of the masterbatch are combined can be obtained. Such a masterbatch is expected to contribute to the expansion of applications of the current inorganic filler-containing polyolefin.

  In the present invention, dispersion of nano-sized inorganic fillers is achieved by preventing the aggregation growth of precursor (metal alkoxide) molecules once uniformly impregnated in polyolefin by the high viscosity of the polyolefin. Surprisingly, the present invention advantageously utilizes high viscosity mixing, which has been an inevitable problem with conventional direct melt mixing of inorganic fillers. The present invention is an epoch-making technology born from the idea of reversing the conventional technology.

  The present invention makes it possible to produce a polyolefin material in a series of processes that were conventionally performed separately in a polymerization plant and a resin compound production plant. As a result, it is possible to manufacture a variety of high-performance polyolefin composites at an appropriate scale and at a low cost. Further, if a high-performance polyolefin composite is used as a master batch, a variety of high-performance polyolefin materials can be produced.

The figure which represented typically the manufacturing process of the highly functional nanocomposite of this invention. IR absorption spectrum of the nanocomposite of Example 5 (Mg (OH) ₂ content: 20% by weight) and Comparative Example 5 (Mg (OH) ₂ content: 20% by weight). TEM photograph of the high-performance nanocomposite obtained in Example 5 (Mg (OH) ₂ content: 20% by weight). The TEM photograph of the comparative nanocomposite obtained in Comparative Example 5 (Mg (OH) ₂ content: 20% by weight). IR absorption spectrum of the nanocomposite obtained in Example 8 (Al ₂ O ₃ content: 2.7% by weight) and Comparative Example 8 (Al ₂ O ₃ content: 3.0% by weight). Example 8: TEM photograph of highly functional nanocomposite obtained in (Al ₂ O ₃ content of 2.7 wt%). Comparative Example 8: TEM photograph of the comparative nanocomposite obtained in (Al ₂ O ₃ content of 3.0 wt%). The graph which shows the heat conductivity of Examples 7-14 and Comparative Examples 7-11. Example 12: TEM photograph of highly functional nanocomposite (Al ₂ O ₃ content of 5 wt%). Comparative Example 9: TEM photograph of the comparative nanocomposite obtained in (Al ₂ O ₃ content of 5 wt%). The ultraviolet visible light absorption spectrum of the film of Example 15, Reference Example 2, and Comparative Example 12. The TEM photograph of the highly functional nanocomposite obtained in Example 15 (TiO ₂ content: 3% by weight). The TEM photograph of the comparative nanocomposite obtained in Comparative Example 12 (TiO ₂ content: 3% by weight). The graph which shows LOI of the composite obtained in Examples 1-6, Reference Example 1, and Comparative Examples 1-6.

[Manufacturing of high-performance nanocomposites containing magnesium hydroxide (Mg (OH) ₂ ), and reference and comparative examples]
Example 1
The highly functional nanocomposite of the present invention was manufactured by the process shown in FIG.
(Step 1) In the polymerization vessel 6, propylene was polymerized using a Ziegler-Natta catalyst (TiCl ₄ / MgCl ₂ / dibutyl phthalate type). The resulting propylene homopolymer 7 had a density of 0.9 g / cm ³ and a melt flow rate (MFR) of 5.0 g / 10 min (JIS K 7210, 1999).
(Step 2) From the line for discharging the polypropylene reactor powder from the polymerizer 6, an anti-aging agent (ADEKA STAB AO-50 manufactured by ADEKA) corresponding to 1.0 wt% concentration was mixed into 4 kg of the reactor powder (not shown). The mixture was introduced into the mixer 8. Separately, in a mixing tank 9, magnesium ethoxide (Mg (OEt) ₂ ) corresponding to 1% by weight in terms of magnesium hydroxide (Mg (OH) ₂ ) was mixed with a mixed solution of methanol and toluene (methanol: toluene = 5: 1 (volume ratio)) at 50 ° C. to prepare 6 L of Mg (OEt) ₂ solution. Next, the Mg (OEt) ₂ solution in the mixing tank 9 was introduced into the mixer 8, and the reactor powder mixture was stirred at 50 ° C. for 12 hours in a nitrogen atmosphere.
(Process 3) The polypropylene powder which completed the process 2 was vacuum-dried in the drying area 10, and the solvent was removed.
(Step 4) The dried propylene powder was exposed to the atmosphere in the humid atmosphere section 13 at room temperature for 75 hours.
(Step 5) The polypropylene powder having finished Step 4 was melt-kneaded with a mixer 14 at 180 ° C. and 100 rpm for 20 minutes. Thus, a highly functional nanocomposite was obtained. The obtained highly functional nanocomposite was pelletized with a granulator 15.

(Example 2)
In step 2, a highly functional nanocomposite was prepared under the same conditions as in Example 1 except that Mg (OEt) ₂ corresponding to 3% by weight in terms of Mg (OH) ₂ was used to prepare 6L of Mg (OEt) ₂ solution. Manufactured, pelletized and stored.
Example 3
In step 2, a highly functional nanocomposite was prepared under the same conditions as in Example 2, except that 8 mg of Mg (OEt) ₂ solution was prepared using Mg (OEt) ₂ corresponding to 5% by weight in terms of Mg (OH) _2. Manufactured, pelletized and stored.
(Example 4)
In step 2, a highly functional nanocomposite was prepared under the same conditions as in Example 2 except that Mg (OEt) ₂ corresponding to 10% by weight in terms of Mg (OH) ₂ was used to prepare 10 L of Mg (OEt) ₂ solution. Manufactured, pelletized and stored.
(Example 5)
In step 2, a highly functional nanocomposite was prepared under the same conditions as in Example 3, except that 12 mg of Mg (OEt) ₂ solution was prepared using Mg (OEt) ₂ corresponding to 20% by weight in terms of Mg (OH) _2. Manufactured, pelletized and stored.
(Example 6)
In step 2, a highly functional nanocomposite was prepared under the same conditions as in Example 4 except that Mg (OEt) ₂ corresponding to 30% by weight in terms of Mg (OH) ₂ was used to prepare 15 L of Mg (OEt) ₂ solution. Manufactured, pelletized and stored.

(IR absorption spectrum)
The high-functional nanocomposite pellets obtained in Examples 1 to 6 were hot-pressed to form a film having a thickness of 100 μm. The IR spectrum of the film was obtained with a Fourier transform infrared spectrophotometer FT / IR-6100 manufactured by JASCO Corporation. In any case, peaks of 450 to 550 and 3690 cm ⁻¹ due to Mg (OH) ₂ were detected. (See FIG. 2) No peaks at 727 and 1080 cm ⁻¹ due to Mg—OC binding were detected. From this, it was confirmed that the conversion from the precursor Mg (OEt) ₂ to Mg (OH) ₂ was completed in the production steps of Examples 1 to 6.

(Reference Example 1)
A product of “ADEKA STAB AO-50” manufactured by ADEKA corresponding to 1.0% by weight was kneaded with the polypropylene reactor powder obtained in Step 1 of Example 1, and a comparative film having a thickness of 100 μm was obtained by hot pressing.

(Comparative Example 1)
4 kg of the polypropylene reactor powder obtained in Step 1 of Example 1 was mixed with ADEKA product “ADK STAB AO-50” corresponding to 1.0% by weight. This polypropylene powder and Mg (OH) ₂ nanoparticle powder (average particle diameter of 100 nm) manufactured by Sigma Aldrich equivalent to 1% by weight were melt-kneaded for 20 minutes at 180 ° C. and 100 rpm using a mixer. Subsequently, the molten polypropylene was formed into a film having a thickness of 100 μm by hot pressing. Thus, a comparative film was obtained.

(Comparative Example 2)
A comparative film was obtained under the same conditions as in Comparative Example 2 except that Mg (OH) ₂ nanoparticles made of Sigma Aldrich equivalent to 3% by weight and polypropylene powder were melt-kneaded.
(Comparative Example 3)
A comparative film was obtained under the same conditions as in Comparative Example 2, except that Mg (OH) ₂ nanoparticles made of Sigma Aldrich equivalent to 5% by weight and polypropylene powder were melt-kneaded.
(Comparative Example 4)
A comparative film was obtained under the same conditions as in Comparative Example 2, except that Mg (OH) ₂ nanoparticles made of Sigma Aldrich equivalent to 10% by weight and polypropylene powder were melt-kneaded.
(Comparative Example 5)
A comparative film was obtained under the same conditions as in Comparative Example 2, except that Mg (OH) ₂ nanoparticles made of Sigma Aldrich equivalent to 20% by weight and polypropylene powder were melt-kneaded.
(Comparative Example 6)
A comparative film was obtained under the same conditions as in Comparative Example 2, except that Mg (OH) ₂ nanoparticles produced by Sigma Aldrich equivalent to 30% by weight and polypropylene powder were melt-kneaded.

The following evaluation was performed about Examples 1-6, Reference Example 1, and Comparative Examples 1-6. Tables 1 and 2 show the results.
(Flame retardance)
The oxygen index (Limited Oxygen Index: LOI) was measured according to ISO 4589-2. Suga Test Instruments Co., Ltd. combustion tester ON2M was used for the actual measuring device. The measurement results are shown in Tables 1 and 2. A graph of the measurement results is shown in FIG. In Comparative Examples 1-6, the flame retardance improvement of polypropylene is hardly recognized. On the other hand, in Examples 1-6, the flame retardance is improved, and in Examples 3-6, the flame retardance is particularly improved. In Example 6, the value of LOI has reached 26.5, and flame retardancy suitable for industrial products that require flame retardancy is achieved. From this result, it can be seen that the production method of the present invention provides a highly functional nanocomposite exhibiting sufficient flame retardancy when the content of magnesium hydroxide as a flame retardant is less than half of the conventional amount.

(Young's modulus)
Dumbbell-shaped test pieces having a thickness of 100 μm were prepared from the films of Examples and Comparative Examples, and a tensile test (Abe Dat-100) was performed at room temperature and a crosshead speed of 1 mm / min. The measurement results are shown in Tables 1 and 2. The examples always show a higher Young's modulus than the comparative examples. From this result, it can be seen that the production method of the present invention provides a highly functional nanocomposite in which the decrease in rigidity due to magnesium hydroxide as a flame retardant is suppressed.

(Tensile strength)
Dumbbell-shaped test pieces having a thickness of 100 μm were prepared from the films of Examples and Comparative Examples, and a tensile test (Abe Dat-100) was performed at room temperature and a crosshead speed of 1 mm / min. The measurement results are shown in Tables 1 and 2. In the examples, the degree of decrease in tensile strength with increasing magnesium hydroxide content is smaller than in the comparative example. From this result, it can be seen that the production method of the present invention provides a highly functional nanocomposite in which the strength reduction due to magnesium hydroxide as a flame retardant is suppressed.

(Form observation of magnesium hydroxide particles)
Example 5 containing 20 wt% magnesium hydroxide was observed by TEM (Figure 3). The film of Comparative Example 5 containing 20% by weight of magnesium hydroxide was observed by TEM (FIG. 4). Ultra-thin sections with a thickness of 100 nm were prepared with an ultramicrotome (Leica ULTRACUTS FCS). Unlike Comparative Example 5, Example 5 shows that magnesium hydroxide is well dispersed as nano-sized particles in polypropylene.

[Production and comparative example of high-performance nanocomposites containing aluminum oxide (Al ₂ O ₃ )]
(Example 7)
(Step 1) Propylene was polymerized in the same manner as in Example 1.
(Step 2) in a mixing vessel 9, and aluminum oxide (Al ₂ O ₃₎ of aluminum isopropoxide, which corresponds to 1% by weight in terms of (Al (OiPr) _3), a catalytic amount of bis (1,2,2,6 , 6-pentamethyl-4-piperidyl) sebacate (hindered amine light stabilizer “ADEKA STAB LA-77” manufactured by ADEKA) was dissolved in heptane at 50 ° C. to prepare 4 L of an Al (OiPr) ₃ solution. Was carried out in the same manner as in Example 1.
(Step 3) Performed in the same manner as in Example 1.
(Step 4) The dried polypropylene powder was transported to the mixer in Step 5 in an air atmosphere.
(Step 5) Performed in the same manner as in Example 1.

(Example 8)
In step 2, a highly functional nanocomposite was produced under the same conditions as in Example 7 except that Al (OiPr) ₃ corresponding to 2.7% by weight in terms of Al ₂ O ₃ was used. “
Example 9
In step 2, a highly functional nanocomposite was produced under the same conditions as in Example 7 except that Al (OiPr) ₃ corresponding to 4.8% by weight in terms of Al ₂ O ₃ was used.
(Example 10)
In step 2, a highly functional nanocomposite was produced under the same conditions as in Example 7 except that Al (OiPr) ₃ corresponding to 9.8% by weight in terms of Al ₂ O ₃ was used.
(Example 11)
In step 2, a highly functional nanocomposite was produced under the same conditions as in Example 7 except that Al (OiPr) ₃ corresponding to 15% by weight in terms of Al ₂ O ₃ was used.

(IR absorption spectrum)
The high-functional nanocomposite pellets obtained in Examples 7 to 11 were melt-extruded and formed into a film having a thickness of 100 μm and used for IR measurement. The IR spectrum of the film was obtained using a Fourier transform infrared spectrophotometer FT / IR-6100 manufactured by JASCO Corporation. In any case, a broad peak in the vicinity of 600 cm ⁻¹ due to Al ₂ O ₃ was detected. A peak at 1040 cm ⁻¹ due to Al—OC bonding was not detected. From this, it was confirmed that the conversion from Al (OiPr) _{3 as} a precursor to aluminum oxide was completed in the production steps of Examples 7 to 11. IR spectra of Example 8 and Comparative Example 8 described later are shown in FIG.

  About the highly functional nanocomposite obtained in Examples 7-11, thermal conductivity was measured by the hot disk method (TPS2500S, 3W, 10s). The results are shown in Table 3.

(Comparative Example 7)
An antioxidant (ADEKA product “ADK STAB AO-50”) was mixed with 4 kg of the polypropylene reactor powder obtained in Step 1 of Example 1 at a concentration corresponding to 1.0% by weight to prepare a polypropylene powder. This polypropylene powder and 1% by weight of Al ₂ O ₃ nanoparticles (AEROSIL product “AEROXIDE Alu C” average particle size 15 nm) were melt-kneaded for 20 minutes at 180 ° C. and 100 rpm using a mixer. . Subsequently, the molten polypropylene was formed into a film having a thickness of 100 μm by hot pressing. Thus, a comparative film was obtained.

(Comparative Example 8)
A comparative film was obtained under the same conditions as in Comparative Example 7 except that ₃ % by weight of Al ₂ O ₃ nanoparticle powder was used.
(Comparative Example 9)
A comparative film was obtained under the same conditions as in Comparative Example 7 except that 5 wt% Al ₂ O ₃ nanoparticle powder was used.
(Comparative Example 10)
A comparative film was obtained under the same conditions as in Comparative Example 7 except that 10% by weight of Al ₂ O ₃ nanoparticle powder was used.
(Comparative Example 11)
A comparative film was obtained under the same conditions as in Comparative Example 7 except that 20% by weight of Al ₂ O ₃ nanoparticle powder was used.

  Table 4 shows the results of measuring the thermal conductivity of the comparative films obtained in Comparative Examples 7 to 11 by the hot disk method (TPS2500S, 3W, 10s).

(Form observation of Al ₂ O ₃ particles)
The film of Example 8 containing 2.7 wt% Al ₂ O ₃ was observed by TEM (FIG. 6). The film of Comparative Example 8 containing 3.0 wt% Al ₂ O ₃ was observed by TEM (FIG. 7). Ultra-thin sections with a thickness of 100 nm were prepared with an ultramicrotome (Leica ULTRACUTS FCS). Unlike Comparative Example 8, in Example 8, it can be seen that Al ₂ O ₃ is well dispersed in the polypropylene as nano-sized particles.

(Example 12)
In Step 5, the same operation as in Example 1 was performed, except that the Al ₂ O ₃ nanoparticle powder used in Comparative Example 7 was added to the polypropylene powder at a concentration of 2.7% by weight, and melted and kneaded with a mixer.
(Example 13)
A test film was prepared under the same conditions as in Example 12 except that Al ₂ O ₃ nanoparticle powder was added at a concentration of 7.3 wt% in Step 5.
(Example 14)
A test film was prepared under the same conditions as in Example 12 except that Al ₂ O ₃ nanoparticle powder was added at a concentration of 17.3% by weight in Step 5.

  About the highly functional nanocomposite obtained in Examples 12-14, thermal conductivity was measured by the hot disk method (TPS2500S, 3W, 10s). The results are shown in Table 5.

FIG. 8 shows a graph of the thermal conductivity values measured in Examples 7-14 and Comparative Examples 7-11. Surprisingly, the high performance nanocomposites produced in Examples 12, 13, and 14 have further improved thermal conductivity than the high performance nanocomposites produced in Examples 7-11. From this, the conventional Al ₂ O ₃ -containing polyolefin composite is mixed with the Al ₂ O ₃ -containing highly functional nanocomposite obtained by the production method of the present invention, thereby significantly increasing the thermal conductivity of the conventional product. I can guess that I can. This indicates that the highly functional nanocomposite of the present invention functions as if it were a masterbatch. The reason why such a masterbatch effect is obtained is not clear, but the high-functional nanocomposite obtained by the production method of the present invention has an effect of enhancing the dispersibility of a normal inorganic filler by some action during melt kneading. I guess that.

(Form observation of Al ₂ O ₃ particles)
The film of Example 12 containing 5 wt% Al ₂ O ₃ was observed by TEM (FIG. 9). The film of Comparative Example 9 containing 5 wt% Al ₂ O ₃ was observed by TEM (FIG. 10). Ultra-thin sections with a thickness of 100 nm were prepared with an ultramicrotome (Leica ULTRACUTS FCS). Compared with Comparative Example 9, it can be seen that in Example 12, the dispersion of Al ₂ O ₃ nanoparticles in polypropylene was greatly improved.

[Manufacture of high-performance nanocomposites containing titanium oxide (TiO ₂ ) and reference / comparative examples]
(Example 15)
(Step 1) Propylene was polymerized in the same manner as in Example 1.
(Step 2) In the mixing tank 9, titanium isopropoxide (Ti (OiPr) ₄ ) corresponding to 3% by weight in terms of titanium oxide (TiO ₂ ) is converted to a catalytic amount of bis (1,2,2,6,6). Example except that 4-pentamethyl-4-piperidyl) sebacate (ADEKA Corporation hindered amine light stabilizer “ADK STAB LA-77”) was dissolved in heptane at 50 ° C. to prepare 4 L of Ti (OiPr) ₄ solution. 1 was performed.
(Step 3) Performed in the same manner as in Example 1.
(Step 4) The dried polypropylene powder was transported to the mixer in Step 5 in an air atmosphere.
(Step 5) Performed in the same manner as in Example 1.

(Comparative Example 12)
To 4 kg of the polypropylene reactor powder obtained in Step 1 of Example 1, an antioxidant (product of “ADEKA STAB AO-50” manufactured by ADEKA) was mixed at a concentration corresponding to 1% by weight to prepare polypropylene powder. This polypropylene powder and 5% by weight of TiO ₂ nanoparticles (Tayka product “NT-500B” average particle size 35 nm) were melt-kneaded for 20 minutes at 180 ° C. and 100 rpm using a mixer. Subsequently, the molten polypropylene was formed into a film having a thickness of 100 μm by hot pressing. Thus, a comparative film was obtained.

(Reference Example 2)
The polypropylene obtained in Step 1 of Example 1 was formed into a film having a thickness of 100 μm by hot pressing. Thus, a comparative film was obtained.

(Ultraviolet ray blocking / visible light transmission)
The ultraviolet-visible light absorption spectra of the films obtained in Example 15, Reference Example 2, and Comparative Example 12 are shown in FIG. From FIG. 11, it can be seen that the film made of the titanium oxide-containing highly functional nanocomposite of the present invention is excellent in ultraviolet cut-off property and high in transparency.

(Observation of TiO ₂ particle morphology)
The film obtained in Example 15 was observed by TEM (FIG. 12). The film obtained in Comparative Example 12 was observed by TEM (FIG. 13). Ultra-thin sections with a thickness of 100 nm were prepared with an ultramicrotome (Leica ULTRACUTS FCS). Unlike Comparative Example 12, it can be seen that in Example 15, TiO ₂ is well dispersed as nano-sized particles in polypropylene.

  According to the present invention, a highly functional nanocomposite in which a metal oxide or metal hydroxide having a low affinity with polyolefin is uniformly dispersed at a nano level without compatibilizer or surface chemical modification is obtained from the polymerization of olefin. It can be manufactured efficiently on a large scale through an integrated process leading to granulation. According to the present invention, it is possible to provide an excellent alternative or improved product of current functional polyolefin materials, masterbatches, inorganic materials, and metal materials used as automobile materials, building materials, electrical and electronic products, and resin modifiers. Be expected.

2: Step 2
3: Process 3
4: Process 4
5: Process 5
6: Polymerizer 7: Polypropylene homopolymer 8: Mixer 9: Mixing tank 10: Drying zone 11: Solvent recovery / separation device 12: Heater 13: Wet atmosphere zone 14: Mixer 15: Granulator

Claims (5)

The manufacturing method of the highly functional nanocomposite which the inorganic filler disperse | distributed to polyolefin which has the following processes.
(Step 1) A step of polymerizing olefins in a polymerization vessel.
(Step 2) A step of mixing the polyolefin reactor powder obtained in Step 1 with a solution of a metal alkoxide, which is a precursor of an inorganic filler, and impregnating the polyolefin powder with a metal alkoxide.
(Step 3) A step of drying the polyolefin powder obtained in Step 2 to remove the solvent.
(Step 4) A step of transferring the polyolefin powder obtained in Step 3 to a humid atmosphere.
(Step 5) A step of completing a sol-gel reaction by melting and kneading polyolefin powder simultaneously with step 4 or subsequent to step 4 to obtain a highly functional nanocomposite. The manufacturing method of the highly functional nanocomposite of Claim 1 whose inorganic filler is a metal oxide or a metal hydroxide. ₂ Inorganic filler _{TiO, SiO 2, ZnO, MgO} , Mg (OH) 2, Al 2 O 3, is Al (OH) ₃ from one or more selected, high-performance nanocomposite of claim 1 or 2 Manufacturing method. The manufacturing method of the highly functional nanocomposite in any one of Claims 1-3 whose highly functional nanocomposite is an object for masterbatches. A highly functional masterbatch comprising a highly functional nanocomposite obtained by the production method according to claim 4.

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