KR20110033334A - Transparent member based on fluororesin composite - Google Patents

Abstract

PURPOSE: A transparent member based on a fluororesin composite is provided to improve gas/drug permeability resistance, dynamic property, and dimensional stability while maintaining light transmissivity. CONSTITUTION: A transparent member based on a fluororesin composite is obtained by separating and drying an aggregate obtained by aggregating an aqueous dispersion. The aggregate is obtained by: freezing the aqueous dispersion at a temperature of 0 °C or less; or changing ionic strength or pH of a mixed solution by adding electrolytic materials; or applying shear force.

Description

Transparent member consisting of composite of fluororesin {TRANSPARENT MEMBER BASED ON FLUORORESIN COMPOSITE}

The present invention provides a fluororesin composite having improved gas permeability, chemical properties, dimensional stability, etc. while maintaining light transmittance by melt molding of a fluorine resin composite composition in which inorganic particles are uniformly dispersed in a fluorine resin at a nano level. It relates to a transparent member made.

Tetrafluoroethylene / perfluoro (alkylvinyl ether) copolymers (PFA), tetrafluoroethylene / hexafluoropropylene copolymers (FEP), and tetrafluoroethylene-ethylene copolymer copolymers (ETFE), which are generally melt-molding fluororesins Etc. are processed by melt extrusion such as tube extrusion or blow molding, and the products such as tubes, hoses, and containers obtained thereby have excellent characteristics such as heat resistance, chemical resistance, and non-adhesiveness, so transfer of chemicals such as acids, alkalis, solvents, paints, etc. It is widely used for pipes, joints, chemical storage containers, or linings such as pipes and tanks. However, these fluororesins, in particular perfluorofluorofluoropolymers, have little intermolecular interactions and thus have problems in mechanical properties, dimensional stability, compression crimp resistance, and the like. For this reason, materials with superior mechanical properties are required. In addition, piping / drug permeability is required for conveying pipes and linings such as chemicals, solvents, and paints.

In many fields, improvements in mechanical strength, dimensional stability, conductivity, thermal conductivity, gas and chemical liquid permeability, and extrusion crimp characteristics have been made by dispersing fillers in resins by requiring resin compositions having better performance. However, when a conventional filler having a particle size larger than the wavelength of visible light, such as carbon black, clay, or graphite, is placed in the resin, the resin composite material becomes opaque, and thus cannot be used as a transparent member. Therefore, it is not suitable for the use of the transparent member such as a reservoir window or a liquid level meter which requires heat resistance or chemical resistance, and a pipe for directly visually confirming the flow of the chemical liquid.

For example, WO2004 / 074371 A1 discloses a fluororesin composite composition in which a layered compound such as clay or graphite is added to a meltable fluororesin and melt mixed to improve mechanical properties such as gas and chemical permeability and elasticity of the meltable fluororesin. It was Japanese Laid-Open Patent Publication No. 2000-190431 also discloses a multilayer laminate in which gas or chemical liquid permeability is reduced by laminating a layer of a meltable fluororesin containing a flaky filler and a layer composed of only a meltable fluorinated resin. It is. However, since the filler particle size used is at least 2 μm or more, the molded article becomes opaque.

In addition, Japanese Patent No. 2002-167488 discloses a composition in which polytetrafluoroethylene having a degree of crystallization is mixed with a meltable fluorine resin to improve resistance to gas resistance. However, since polytetrafluoroethylene particles having high crystallinity are opaque, increasing the polytetrafluoroethylene content lowers the gas permeability, and the permeability of the molded article made of the composition is lowered.

Recently, many methods have been performed to directly melt-mix nanoparticles such as inorganic particles into a polymer material to improve mechanical properties, thermal strain, dimensional stability, and the like. However, when the inorganic fine particles or inorganic nanoparticles are melt-mixed into the resin, the smaller the particle size, the greater the cohesive force of the fine particles, and reaggregation occurs between the particles. It is extremely difficult. (Materials of Materials Research Association, Vol.47, p150, 2003)

To the fluororesin emulsion, silicon carbide particles having an average particle size of 4 μm surface-treated with an amino silane-based surface treatment agent were added, and then nitric acid was added to break the fluororesin emulsion, and trichlorotrifluoroethane was further added. A method for obtaining agglomerated powders having an average particle size of 3 mm by addition, agglomeration and granulation was disclosed in the Examples. (Japanese Patent Laid-Open No. 7-64926). However, in this specification, the molten molded article becomes opaque because silicon carbide powder having a particle size of 4 µm is added to the fluororesin emulsion in order to agglomerate instead of the inorganic fine particle colloidal solution.

Accordingly, the technical problem of the present invention is to provide a transparent member made of a fluorine resin composite composition excellent in gas, chemical liquid permeability, and mechanical properties made of a fluorine resin composite composition in which inorganic fine particles are dispersed in a fluorine resin at a nano level.

In addition, unlike conventional fluorine resin composite compositions containing micro-level fillers, transparent members made of fluororesin composites having improved mechanical properties such as elastic modulus while maintaining MFR or elongation even when inorganic particulate content such as silica is increased to 15 to 20% by weight To provide.

The transparent member made of the fluororesin composite composition of the present invention is a fluororesin emulsion and an aqueous acidic solution obtained by stirring / mixing an inorganic fine particle colloidal solution having an average particle size of 400 nm or less and 0.5 to 40% by weight relative to the fluororesin emulsion. Agglomerates obtained by freezing at the following temperature, adding an electrolytic material to change the ionic strength or Ph of the mixed solution, or applying a shearing force, are separated and dried from an aqueous solution.

Preferably, the fluororesin emulsion is tetrafluoro-ethylene, hexafluoro-propylene, chlorotrifluoro ethylene, perfluoro (alkyl vinyl ether), Characterized in that it is a polymer or copolymer of monomers (monomers) selected from vinylidene fluoro (vinylidene fluoro) and vinyl fluoride (vinylidene fluoride).

Preferably, the inorganic fine particle colloidal solution is at least one inorganic fine particle colloidal solution selected from silicon oxide, coral titanium, aluminum oxide, a double oxide combined with zinc oxide and antimony pentoxide.

Preferably, the nitrogen gas permeability of the fluororesin emulsion is characterized in that less than 75% of the fluororesin.

According to the present invention It is possible to provide a transparent member excellent in gas, chemical permeability, and mechanical properties, which is composed of a fluorine resin composite composition in which inorganic fine particles are uniformly dispersed at a nano level in a fluorine resin.

In addition, unlike the fluorine resin composite composition containing the conventional micro-level filler, the inorganic particles such as silica can improve the mechanical properties such as elastic modulus while maintaining the MFR or elongation even if the inorganic particulate content such as silica is increased to 15 to 20% by weight. .

In addition, the transparent member of the present invention can be molded into various molded articles such as containers, tubes, sheets, films, rods, fibers, wire coating, and electronic materials.

The transparent member of the present invention is useful for applications such as windows such as reservoirs requiring heat resistance and chemical resistance, transparent members such as liquid level gauges, and piping for directly visually confirming the flow of chemical liquids. In addition, in the fluorine resin composite composition in which metal oxides such as silica are dispersed in the fluorine resin at a nano level, gas and chemical liquid permeability decrease with increasing silica content. It is also useful as a molding material or as a pipe or lining material. It can also be used in various applications such as scratch resistant films, transparent films, transparent tubes, and electronic materials.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

As a fluororesin emulsion used for this invention, it can select suitably from a known fluororesin emulsion. Examples of such fluororesin emulsions include tetrafluoro ethylene (TFE), chlorotrifluoro ethylene (CTFE), trifluoro ethylene, hexafluoro propylene (HFP), perfluoro alkyl vinyl ether (PAVE), and vinylidene fluorine (VdF). And polymers or copolymers of monomers selected from vinyl fluorine (VF), or monomers having a double bond such as ethylene, propylene, butylene, pentene, hexene, triplets such as acetylene and propene. The copolymer emulsion with the monomer which has a bond, etc. are mentioned.

Specific examples of the fluororesin include polytetrafluoroethylene (hereinafter referred to as PTFE), TFE / PAVE copolymer (hereinafter referred to as PFA), TFE / HFP copolymer (hereinafter referred to as FEP), TFE / HFP / PAVE copolymer (EPE), Tetrafluoro ethylene / ethylene copolymer (ETFE), polyvinylidene fluoride (PVdF), polychlorotrifluoro ethylene (PCTFE), chlorotrifluoro ethylene / ethylene copolymer (ECTFE), TFE / VdF copolymer, TFE / VF Copolymers, TFE / HFP / VF copolymers, HFP / VdF, VdF / CTFE co-polymers, TFE / VdF / CTFE copolymers, TFE / HFP / VdF copolymers, and the like. Among these, as for the copolymer of tetrafluoro ethylene and perfluoro (alkyl vinyl ether), the alkyl group of perfluoro ethylene and perfluoro (alkyl vinyl ether) has C1-C5, especially 1-3 are preferable. Particle dispersions of these polymers are usually prepared by emulsion polymerization.

According to the present invention, a colloidal resin in which a resin primary particle is surrounded by a surfactant and stably dispersed in a solvent, and an electric double layer is formed on the surface of the inorganic fine particles, and the inorganic fine particles are stably dispersed by the repulsive force between the inorganic fine particles. The solution is stirred to obtain an aqueous dispersion in which resin primary particles and inorganic fine particles are uniformly mixed. Thereafter, by agglomeration, the homogeneous mixed state of the resin primary particles and the inorganic fine particles is fixed, and the obtained aggregate is separated and dried from an aqueous solution to obtain a fluororesin composite composition in which the inorganic fine particles are uniformly dispersed at a nano level in the resin. Therefore, the present invention provides a dry powder of aggregates in which resin primary particles and inorganic fine particles are uniformly dispersed by agglomeration and drying of a mixed solution. Thus, it is possible to obtain emulsion powders regardless of melting point and melt mixing characteristics of the fluorine resin used. Any fluororesin emulsion can be used.

The particle size of the resin primary particles in the fluororesin emulsion also depends on the particle size of the inorganic fine particles in the colloidal solution used, for example, 50 to 500 nm, preferably 70 to 300 nm.

The fluorine resin composite composition in which inorganic fine particles are uniformly dispersed at a nano level in the meltable fluorine resin of the present invention can maintain the elongation rate or meltability of the meltable fluorine resin even when 15 wt% of the inorganic fine particle aggregates are added. have. Therefore, there is no particular limitation on the melt viscosity or molecular weight of these fluororesins, and an appropriate range can be selected according to the intended use. For example, for injection molding purposes, 7-40 g / 10 min is preferable in terms of melt flow rate (MFR melt flow rate).

In the present invention, a sol in which inorganic fine particles are stably dispersed is used. Examples of the inorganic fine particles of the sol include silicon oxide (SiO ₂ ), titanium oxide (TiO ₂ ), zeolite, zirconium oxide (ZrO ₂ ), and alumina (AL _2). O ₃ ), zinc oxide (ZnO) and antimony pentoxide are preferred. Moreover, according to the objective, you may use individually or in combination, and may select and use the said or another microparticle. The other fine particles include silicon oxide (SiC), aluminum nitride (AIN), silicon nitride (Si ₃ N ₄ ), barium titanate (BaTiO ₃ ), boron nitride, lead oxide (lead oxide), tin oxide, Examples of the metal particles include chromium oxide, chromium hydroxide, cobalt titanate, cerium oxide, magnesium oxide, selium zirconate, calcium silicate, zirconium silicate, gold, silver, copper, transition metals, and the like.

The inorganic fine particle sol of the present invention is preferably stabilized in a solution state by various electrolytes, organic additives and the like. For example, as a colloidal silica sol, a colloidal solution in which negatively charged silicon oxide nanoparticles are dispersed in water, and a silanol group and a hydroxyl group are present on the surface of the particle, The middle layer is formed and stable due to interparticle repulsion. Generally, when the particle size of the filler dispersed in the resin is larger than the visible light wavelength, the resin composite tends to be opaque. Therefore, the average particle size of the inorganic fine particles of the sol is usually 10 nm to 400 nm, preferably 15 nm to 350 nm, 20 nm-300 nm are more preferable. In general, when the particle size of the inorganic fine particles is 500nm or more, the inorganic fine particles may settle and the storage stability of the colloidal sol may be reduced.

If inorganic sol is used as a sol having high purity and a fluorine resin emulsion with few impurities, a high purity can be obtained as the resulting fluororesin composite composition. For example, when a fluororesin emulsion containing few impurities such as ultra high purity colloidal silica and metal ions is used as a silica sol, a highly pure fluororesin composite composition can be obtained. The molded article made of the extremely high fluorine resin composite composition thus obtained is also very suitable as a component to be used in a semiconductor manufacturing apparatus or the like requiring purity. As ultra-high purity colloidal silica, PL series of FUSO Chemical Industries, Ltd. is marketed.

In the present invention, a colloidal solution in which a resin primary particle is surrounded by a surfactant and stably dispersed in a solvent, and an electric double layer is formed on the surface of the inorganic fine particles so that the inorganic fine particles are stably dispersed by the repulsive force between the inorganic fine particles. The mixture is stirred to obtain an aqueous dispersion in which the resin primary particles and the inorganic fine particles are uniformly mixed. Thereafter, by agglomeration, the homogeneous mixed state of the resin primary particles and the inorganic fine particles is fixed, and the aggregates are separated and dried from the aqueous solution to obtain a fluororesin composite composition in which the inorganic fine particles are uniformly dispersed at a nano level in the resin. As a coagulation method of the aqueous acid solution in which the resin primary particles and the inorganic fine particles are uniformly mixed, the resin emulsion and the inorganic fine particle sol mixed solution are stirred with a strong shearing force by a stirring device to destroy and aggregate the micelle structure, which is a surfactant in the fluororesin emulsion. Method (Physical Agglomeration), Method of adding the electrolytic material to the resin emulsion and the inorganic fine particle sol mixture to change the ionic strength or PH, thereby rapidly decreasing the stability of the resin emulsion or the inorganic fine particle colloid (chemical aggregation), the resin emulsion and the inorganic fine particles. And a method (freezing agglomeration) of the latex particles or the colloidal particles by compression between the ice crystals by ice crystal growth generated by freezing the sol mixture solution.

Above all, electrolytic materials such as inorganic salts are added to the fluororesin emulsion and the inorganic fine particle sol mixture to drastically reduce the stability of the resin emulsion or the inorganic fine particle colloidal solution, and to uniformly fix the homogeneous mixed state of the resin primary particles and the inorganic fine particles at the same time. Chemical agglomeration method is preferred in which the aggregates are uniformly dispersed. Depending on the type and proportion of the resin primary particles or inorganic fine particles in the mixed solution before chemical flocculation, for example, as an electrolytic substance used for the purpose of chemical flocculation of the fluororesin primary particles of the fluororesin emulsion, melting _{HCI, H 2 SO 4, H} 3 PO 4, Na 2 SO, MgCI 2, CaCl 2, formic acid can be exemplified inorganic or organic compounds such as sodium, potassium jaksan, ammonium carbonate. Of these, compounds that can be volatilized later in the aggregate drying step, such as HCI, HNO ₃ , ammonium carbonate, or the like, are preferably used. In addition to the above electrolytic materials, hydrochloric acid, phosphoric acid, lactic acid, molybdate, alkali metal nitrate salts, alkaline earth metal salts, ammonium salts and the like, and more preferably potassium embrittlement, potassium nitrate, potassium iodide (KI), ammonium molybdate and dihydrogen phosphate. Inorganic salts such as sodium, ammonium embrittlement (NH ₄ Br), potassium chloride, calcium chloride, copper chloride and calcium nitrate may be used alone or in combination. These electrolytes are also based on the type of electrolyte, the solid concentration of the hydrophobic emulsion and the inorganic particulate sol, and the ratio of 0.001 to 15% by weight, especially 0.05 to 10% by weight, relative to the weight of the mixture of the fluororesin emulsion and the inorganic fine particle sol. It is preferable to use as. It is also preferable to add the fluororesin emulsion and the inorganic fine particle sol mixture liquid in the form of an aqueous solution. If the amount of the electrolytic material used is too small, there may be a partial coagulation, so the resin composite composition in which the uniform mixing state of the resin primary particles and the inorganic fine particles cannot be fixed at once and the inorganic fine particles are uniformly dispersed in the resin. There is a case where you do not get.

The concentration of the fluororesin emulsion and the inorganic fine particle sol is based on the solid concentration of the fluororesin emulsion and the inorganic fine particle sol. It is also possible to stir and mix after adjusting solid content concentration by this.

The apparatus for agitating the fluororesin emulsion and the inorganic fine particle sol to uniformly mix the resin primary particles and the inorganic fine particle and then to agitate the mixed solution physically or chemically is not particularly limited, but a stirring means capable of controlling the stirring speed, for example, , Propeller blades, turbine blades, paddle blades, furnace blades, horseshoe wings, spiral blades and the like are preferably provided with drainage means. By adding and stirring a fluororesin emulsion, an inorganic fine particle sol, and an electrolytic substance in such an apparatus, colloidal particles and / or inorganic fine particles of the resin aggregate to form an aggregate and are separated from an aqueous medium. The stirring speed of the step of separating the aqueous medium from the aggregate is preferably 1.5 times faster than the stirring speed of the fluororesin emulsion and the inorganic fine particle sol mixing step. The aggregate is washed with water if necessary after discharge of the aqueous medium, and dried at a temperature not higher than the melting point of the resin or the thermal decomposition start temperature to obtain a fluororesin composite powder. The drying temperature is preferably a temperature at which the electrolytic material, surfactant, or the like is volatilized below a temperature at which fluorine resin thermal degradation or decomposition does not occur.

The content of the inorganic fine particles in the fluororesin composite composition is based on the use of the resin composite composition, but is 0.1 to 80% by weight, preferably 0.3 to 50% by weight, and most preferably 0.5 to 40% by weight based on the fluororesin composite. In the nano resin mixture or the so-called polymer nanocomposite in which the inorganic fine particles are dispersed at the nano level in the resin, the inorganic fine particles are significantly increased since the interface area between the nano particles and the resin matrix is significantly increased compared to the conventional resin composite mixture in which the filler is dispersed at the micron level. It can be expected to improve the physical properties even if put a small amount than the conventional resin composite mixture. In addition, the resin nanocomposites may become transparent when inorganic particles having a smaller particle size than the visible light wavelength are uniformly dispersed at the nano level. Furthermore, in the fluorine resin composite composition in which metal oxides such as silica are dispersed in the fluorine resin at a nano level, the gas and chemical permeation rate decreases with increasing silica content.

In the present invention, the aggregated dry powder in which the fluororesin primary particles and the inorganic particles are uniformly dispersed in the frying drying process is usually pelletized through a melt extruder and then melt molded, such as extrusion, injection molding, transfer molding, blow molding, or the like. Can be. Of course, the pelletized agglomerate powder may be directly formed as a raw material, or the agglomerated powder may be hardened by a compactor so that the agglomerated powder penetrates into a molding machine hopper. In the aggregate dry powder sample and the sample pelletized by the melt extruder, the inorganic fine particle dispersion state in the fluororesin was almost the same (see FIGS. 1 and 2). In addition, the aggregated powder of different particles in which the fluororesin primary particles and the inorganic fine particles uniformly dispersed in the present invention can be granulated to be used as a material for powder molding, powder coating or rotational molding.

When pelletizing through a melt extruder, it is preferable to use the twin screw extruder with a big shear stress.

Agglomerates of fluororesin primary particles and heteroparticles in which inorganic particles are uniformly dispersed in the drying process can be uniformly dispersed even by melt mixing using a twin screw extruder, and can be more uniformly dispersed by melt mixing. .

In addition, additives may be blended or mixed with other resins within a range where transparency is not impaired in the process of pelletizing through a melt extruder. Additive compounding can be performed not only in a melt extrusion process but also in the mixing process of the said resin emulsion and an inorganic fine particle sol. Such additives may include nanoparticles of layered silicon compounds such as mica and clay.

There is no particular limitation regarding the molding method and conditions for obtaining the molded article of the present invention. Molding methods and conditions that have been applied to meltable fluorine resins, that is, extrusion conditions for tubes, sheets, films, rods, fibers, wire coatings, blow molding conditions for containers, etc., injection molding for trays The conditions can be used as they are. Powder molded articles, powder coated molded articles, and rotomolded articles can also be obtained.

In particular, molded articles obtained by molding a fluororesin composite composition in which inorganic particles having a particle size of 400 nm or less, more preferably 350 nm or less, are uniformly dispersed in the fluorine resin matrix to the nano level become transparent because the particle size of the non-particulate particles is smaller than the visible light wavelength. Therefore, it is useful for applications such as windows of reservoirs, liquid level gauges and the like where heat resistance and chemical resistance are required, and piping where the liquid flow can be seen directly. Furthermore, in the fluorine resin composite composition in which silicon oxides such as silica are dispersed in the fluorine resin, the gas and chemical liquid permeability decreases with the increase of the silica content. It is also useful as a material or as a piping or lining material. It can also be used for various applications such as scratch resistant films, transparent films, transparent tubes, and electronic materials.

Although an Example and a comparative example are given to this invention further below, this description does not limit this invention.

In this invention, the measurement of each physical property with respect to PFE was performed by the following security.

(A. Measurement of Physical Properties)

(1) melting point (melting peak temperature)

A differential irradiation calorimeter (Pyris type DSC, manufactured by perkinelmer) was used. About 10 mg of a sample is weighed and put into a dedicated aluminum pan, and it crimps with a dedicated crimper, it is stored in a DSC main body, and the temperature is raised to 10 degree-C / min to 150 degreeC-360 degreeC. The melting peak temperature (Tm) was obtained from the melting curve obtained at this time.

(2) Melt Flate (MFR)

5 kg of sample powder is filled in a cylinder maintained at 372 ± 1 ° C for 5 minutes using a melt indexer (product of TOYO SEIKI) equipped with a corrosion resistant cylinder, die, and piston according to ASTM D 1238 95. Extrusion was carried out through the die orifice under (piston and weight), at which time the extrusion rate (g / 10min) was determined by MFR.

(3) silica dispersion state

The fluororesin composite composition was melt-compressed at 350 ° C, and three 10 mmX10 mm specimens were cut from three samples of about 0.2 mm in thickness, and aggregated with silica nanoparticles of 10 μm or more using an optical microscope (NIKON, OPTIPHOT2 POL). The dispersion state was evaluated for the presence or absence. Only samples with no aggregates composed of silica particles of 10 μm or more were observed. The fracture surfaces prepared in liquid nitrogen were observed in three places for each sample by scanning electron microscope, and the dispersion state of silica was evaluated according to the following criteria.

In the electron microscope observation, almost the silica was dispersed to the primary particles.

Very little aggregates of silica nanoparticles remain.

Many aggregates of silica nanoparticles of 10 m or more remain in the X optical microscope.

(4) Tensile Properties (Tensile Strength, Elongation, Tensile Elasticity)

A sample of about 1 mm in thickness produced by melt compression molding the fluororesin composite composition at 350 ° C. was measured at a tensile rate of 50 mm / min in accordance with JIS K 7127.

(5) light transmittance

A 50mmX50mm specimen was prepared from a sample of about 1 mm thick prepared by melt compression molding the fluororesin composite composition at 350 ° C, and measured using a Haze-Meta NDH2000 (light source is halogen lamp D65) manufactured by NIPPON DENSYOKU INDUSTRIAL CO., LTD. And measured according to JIS K7136. The light transmittance was calculated from five sample average values.

(6) Nitrogen Gas Permeability

The fluororesin composite composition was melt-compression-molded at 350 ° C., and the sheet having a thickness of about 0.3 mm and a diameter of 130 mm was measured at a temperature of 23 ° C. using a gas permeation measuring device (160 ml of S 69 type) manufactured by SIBATA SCI. Measurements are expressed in 10 ¹¹ cm ³ (STP) sm / cm ² .sec.cmHg.

(B. raw materials)

Raw materials used in Examples and Comparative Examples of the present invention are as follows.

(1) PFA emulsion

PFA aqueous acid solution obtained by emulsion polymerization (PFA solid content: 29 wt%, PFA primary particle average particle size: 200 nm, Ph: 9, melting point: 309 DEG C, melt florate: 2 g / 10 min).

(2) Silica Sol (FUSO Chemical Industries, Ultra High Purity Colloidal Silica)

(a) PL 3 (silica: 19.5% by weight, silica primary particle size: 35mn, ph: 7.2)

(b) PL 7 (silica: 22.7 wt%, silica primary particle size: 70mn, ph: 7.2)

(c) PL 13 (silica: 24 wt%, silica primary particle size: 130mn, ph: 7.2)

(d) PL 20 (silica: 24 wt%, silica primary particle size: 220mn, ph: 7.2)

(3) fused silica

DENKI CHEMICAL PRODUCT FB 74 (Average Silica Particle Size: 32000nm)

(Example 1)

Put 269.9G of silica sol (PL 3) and 270g of water (pure water) into a beaker (8L) and stir at 140rpm for 15 minutes using a downflow type propeller-type agitator.Then, the silica content was added to the PFA resin composite. 3380 g of the PFA aqueous acid solution obtained in the emulsion polymerization was added to 5% by weight, followed by stirring at 300 rpm for 30 minutes to obtain a uniform dispersion. 13 g of 60% nitric acid was added to the mixture to stir until fluidity disappeared. The resin primary particles and the silica nanoparticles were aggregated at once. The gel aggregate thus obtained was stirred at 450 rpm again for 10 minutes to separate the aggregate from the aqueous medium to remove excess water. The remaining aggregate was dried at 170 ° C. for 10 hours to obtain aggregate dry powder. The aggregate dry powder was melt mixed at 340 ° C. and 240 rpm for 1 minute and 40 seconds using a melt mixer (TOYO SEIKI KF 70V small segment mixer) to obtain a fluororesin composite composition. The fluororesin composite composition was compression molded at 350 ° C. in small pieces of 3 mm in size, and tensile property, MFR measurement, optical and electron microscope observation, and light transmittance measurement were performed using a sample having a thickness of about 1.0 mm. Are shown in Table 1 and Table 2. As a sample for nitrogen gas permeability measurement, a compression molding sheet having a thickness of about 0.3 mm was used.

(Example 2)

231.9 g of silica sol (PL 7) and 270 g of water (pure water) were placed in a beaker (8L), and stirred at 140 rpm for 15 minutes using a downflow propeller type four-winged stirrer, and the silica content was added to the PFA resin composite. 3380 g of the PFA aqueous acid solution obtained in the emulsion polymerization was added to 5% by weight, and the dry powder of the aggregate and the melt-mixed fluororesin composite composition were obtained in the same manner as in Example 1. Electron microscopy observations of samples of 1 mm thickness obtained by compression molding the fluororesin composite composition obtained by melt mixing at 350 ° C are shown in Fig. 1 and Fig. 2. Tensile properties, MFR measurement, optical and electron microscope observation, light transmittance measurement, and nitrogen gas permeability measurement of the melt-mixed fluororesin composite composition were carried out. The results are shown in Tables 1 and 2.

(Example 3)

489.5 g of silica sol (PL 7) and 270 g of water (pure water) were placed in a beaker (8 L) and stirred at 140 rpm for 15 minutes using a stirring apparatus with four downflow propeller-type blades. 3380 g of the PFA aqueous acid solution obtained in the emulsion polymerization was added so as to be 10% by weight, and the dry powder of the aggregate and the melt-blended fluororesin composite composition were obtained in the same manner as in Example 1. The fluororesin composite composition obtained by melt mixing was compression molded at 350 ° C. to measure tensile properties, MFR, nitrogen gas permeability, optical and electron microscope, and light transmittance. The results are shown in Tables 1 and 2.

(Example 4)

777.4 g of silica sol (PL 7) and 770 g of water (pure water) were placed in a beaker (8L), and stirred at 140 rpm for 15 minutes using a stirring apparatus with four downflow propeller-type blades. 3380 g of the PFA aqueous acid solution obtained in the emulsion polymerization was added to 15% by weight, and the dry powder of the aggregate and the melt-mixed fluororesin composite composition were obtained in the same manner as in Example 1. The fluororesin composite composition obtained by melt mixing was compression molded at 350 ° C. to measure tensile properties, MFR, nitrogen gas permeability, optical and electron microscope, and light transmittance. The results are shown in Tables 1 and 2.

(Example 5)

1107.3 g of silica sol (PL 7) and 1100 g of water (pure water) were placed in a beaker (8 L) and stirred for 15 minutes at 140 rpm using a stirring device with four downflow propeller-type blades. 3380 g of the PFA aqueous acid solution obtained in the emulsion polymerization was added to 20% by weight, and the dry powder of the aggregate and the melt-mixed fluororesin composite composition were obtained in the same manner as in Example 1. The fluororesin composite composition obtained by melt mixing was compression molded at 350 ° C. to measure tensile properties, MFR, nitrogen gas permeability, optical and electron microscope, and light transmittance. The results are shown in Tables 1 and 2.

(Example 6)

219.3 g of silica sol (PL 13) and 220 g of water (pure water) were placed in a beaker (8 L) and stirred at 140 rpm for 15 minutes using a stirring device with four downflow propeller blades. 3380 g of the PFA aqueous acid solution obtained in the emulsion polymerization was added to 5% by weight, and the dry powder of the aggregate and the melt-mixed fluororesin composite composition were obtained in the same manner as in Example 1. The fluororesin composite composition obtained by melt mixing was compression molded at 350 ° C. to measure tensile properties, MFR, nitrogen gas permeability, optical and electron microscope, and light transmittance. The results are shown in Tables 1 and 2.

(Example 7)

219.3 g of silica sol (PL 20) and 220 g of water (pure water) were placed in a beaker (8L) and stirred for 15 minutes at 140 rpm using a stirring device with four downflow propeller type blades, and then the silica content was added to the PFA resin composite. 3380 g of the PFA aqueous acid solution obtained in the emulsion polymerization was added to 5% by weight, and the dry powder of the aggregate and the melt-mixed fluororesin composite composition were obtained in the same manner as in Example 1. The fluororesin composite composition obtained by melt mixing was compression molded at 350 ° C. to measure tensile properties, MFR, nitrogen gas permeability, optical and electron microscope, and light transmittance. The results are shown in Tables 1 and 2.

(Comparative Example 1)

Solution silica with an average particle size of 32000 nm and PFA pellets, which are heat-melt resins, were melt-blended at a temperature of 340 ° C and 240 rpm for 1 minute and 40 seconds using a melt mixing apparatus (KF 70V small-segment mixer manufactured by TOYO SEIKI Co., Ltd.). A composite composition was obtained in which 32000 nm of microscale silica was dispersed in a fluororesin. The obtained sample was compression molded at 350 ° C., and tensile property, MFR measurement, optical and electron microscope observation, and light transmittance measurement were performed using a sample having a thickness of about 1.0 mm. The results are shown in Tables 1, 2, and 3.

(Reference Example 1)

The physical properties of only the fluorine resin containing no silica are shown in Tables 1 and 2.

TABLE 1

PFA
weight(%) Silica
weight(%) Physical properties of the composition Primary particle
(nm) MFR
(g / 10 min) The tensile strength
(MPa) Elongation
(%) Tensile Modulus
(MPa) Silica
Dispersion Example 1 95 5 35 2.1 31.5 350 560 ○ Example 2 93 5 70 2.1 32.9 356 540 ◎ Example 3 90 10 70 1.8 28.7 341 703 ◎ Example 4 85 15 70 1.5 24.8 302 750 ◎ Example 5 80 20 70 1.1 18.3 192 884 ◎ Example 6 95 5 130 2.2 32.2 341 540 ◎ Example 7 95 5 220 2.1 34.1 355 520 ◎ Comparative Example 1 95 5 32000 1.7 22.5 252 452 X Reference Example 1 100 0 - 2.0 32.1 353 420 -

TABLE 2

PFA
weight(%) Silica Composition Properties weight
(%) Primary particle
(nm) Light transmittance
(%) Nitric Acid Permeability
(*) Silica
Dispersion Example 1 95 5 35 75 0.83 ○ Example 2 95 5 70 71 0.86 ◎ Example 3 90 10 70 72 0.79 ◎ Example 4 85 15 70 70 0.75 ◎ Example 5 80 20 70 71 0.68 ◎ Example 6 95 5 130 71 0.82 ◎ Example 7 95 5 220 70 0.84 ◎ Comparative Example 1 95 5 32000 35 0.98 X Reference Example 1 100 0 - 86 1.12 -

In the results shown in Table 1, the fluororesin composite composition (Examples 1 to 7) according to the present invention was nano-dispersed silica. In addition, when the silica content is 5%, when the silica is nano-dispersed, the MFR is slightly higher than the fluorine resin alone (Reference Example 1). However, when silica was not nano-dispersed (Comparative Example 1), MFR was lower than that of the fluorine resin group at 5% as in the conventional micro composite.

When the silica primary particle size was constant, when the silica content increased to 5%, 10% and 15%, the modulus of elasticity was increased while maintaining the MFR and elongation to some extent. In the conventional microcomposites, the MFR and elongation rate are significantly decreased as the filler content increases. Therefore, it is possible to maintain the MFR and elongation rate to some extent even if the silica content is increased. It is thought to be the result.

In addition, from the electron microscope observation results of the fluorine resin composite composition (FIG. 1) and the fluorine resin composite composition (FIG. 2) in which the dry powder was melt-mixed again in the aggregate dry powder state, there was no difference in the nano dispersion state of silica. . Therefore, it is thought that the silica is dispersed in the fluorine resin even in the aggregate powder state.

In the results shown in Table 2, silica was nano-dispersed so that the light transmittance of the sample became 70% or more and became transparent. Particularly, when the silica particle size was 70 nm, the light transmittance was maintained at about 70% even when the silica content was increased from 5% to 20% (Examples 2 to 5). Moreover, even if the silica primary particle size became 220 nm (Example 7), the light transmittance was about 70% and the transmittance | permeability was maintained. This may be because silica having a particle size smaller than the wavelength of visible light (400 nm to 700 nm) is uniformly dispersed in the fluororesin. However, when the silica particle size was 32000 nm (Comparative Example 1), the light transmittance became 35% and became opaque. In addition, the permeability of nitrate was decreased with increasing silica content (Examples 2 to 5).

1 is an electron micrograph showing the silica dispersion of the aggregate dry powder sample obtained in Example 2.

Figure 2 is an electron micrograph showing the silica dispersion of the fluororesin composite composition after melt mixing used in Example 2.

Figure 3 is an electron micrograph showing the silica dispersion of the fluororesin composite composition used in Comparative Example 1.

Claims (4)

The aqueous component obtained by stirring / mixing the fluororesin emulsion and the inorganic particulate colloidal solution having an average particle size of 400 nm or less and 0.5 to 40% by weight of the fluororesin emulsion was frozen at a temperature of 0 ° C. or below, or by adding an electrolytic material. A transparent member made of a fluororesin composite composition obtained by separating / drying an aggregate obtained by changing an ionic strength or Ph or applying a shear force from an aqueous solution. The method of claim 1, wherein the fluororesin emulsion is tetrafluoro-ethylene, hexafluoro-propylene, chlorotrifluoro ethylene, perfluoro (alkyl vinyl ether) (perfluoro; alkyl vinyl A transparent member comprising a fluororesin composite, characterized in that the polymer (polymer) or copolymer of a monomer (monomer) selected from ether, vinylidene fluorine and vinyl fluoride (vinylidene fluoride). The fluororesin composite according to claim 1, wherein the inorganic fine particle colloidal solution is at least one inorganic fine particle colloidal solution selected from a complex oxide in which silicon oxide, coral titanium, aluminum oxide, zinc oxide and antimony pentoxide are combined. Transparent member made of composite material. The transparent member of claim 1, wherein the nitrogen gas permeability of the fluororesin emulsion is 75% or less of the fluororesin.

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