JPH04288353A - Amorphous silica filler - Google Patents

Abstract

PURPOSE:To provide an amorphous silica filler, especially an antiblocking agent excellent in handleability, process-ability, dispersibility and abrasion resistance and, when used in a resin, excellent in mar resistance between films. CONSTITUTION:An amorphous silica having a substantially spherical apperance and a mean primary particle size of 100-270nm when determined with a scanning electron microscope, an apparent specific gravity of 0.24-0.55g/cm<3>, a BET specific surface area of 200-500m<2>/g, an oil absorption of 50-120ml/g and a degree of agglomeration (DA) defined as a radio of a mean primary particle diameter (D1) to a coarse particle diameter (D0) of 10-50 is used as a filler. This filler comprises substantially spherical particles which are dense and have a low oil absorption though they have a large specific surface area and therefore it excels in handleability, processability, transparency and antiblocking properties and can give a film excellent in mar resistance when used in a resin.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention relates to an amorphous silica filler, and more specifically, it has excellent handling and processability, and when added to a resin film. This invention relates to an amorphous silica filler that enables resin films with excellent dispersibility, transparency, and anti-blocking properties, and with excellent scratch resistance that does not cause scratches on the film surface even when the films are rubbed together. . [0002] As amorphous silica fillers, so-called dry process silica and wet process silica are known, and their respective properties are utilized to fill paints, information recording paper, etc. Used for rubber, resin molded products, etc. The former silica is obtained by decomposing SiCl4 in an oxygen-hydrogen flame, has a fine particle size and a spherical shape, and has a relatively low surface activity based on specific surface area, pore volume, pore distribution, etc. On the other hand, the latter silica is obtained by neutralizing an alkali silicate with an acid, and is generally large in particle size and has a wide particle size distribution, but its interior is porous and has a relatively high surface activity. As described above, the physical properties of amorphous silica vary greatly depending on the manufacturing method. In particular, the latter wet method requires concentration, temperature, pressure, time, reaction method, etc. as reaction conditions for neutralizing alkali silicate with acid. Since the conditions can be changed in various ways, it is possible to obtain amorphous silica with widely different properties. [0003] For example, silica hydrogel (Japanese Patent Publication Publication No. 48 Sho.
-13834, Japanese Patent Application Laid-Open No. 63-16049)
In addition, acid-cured silica hydrogel was acid-washed to pH
Water-containing silica gel having a water content of 20 to 50% by weight (Japanese Patent Publication No. 2-1764) is known, which is obtained by forming a silica hydrogel of 2.5 to 5%, followed by drying and pulverizing. In addition to the above-mentioned amorphous silica, inorganic fine powder particles have also been widely used as anti-blocking agents for resin films. For example, a method of adding fine powder silica whose surface silanol groups are substituted with lipophilic groups to improve transparency and anti-blocking properties (Japanese Patent Publication No. 49-41099), biaxial unoriented polypropylene A method of improving anti-blocking properties by adding zeolite particles to a film (Japanese Patent Publication No. 16134/1983), and a method of improving anti-blocking properties by adding zeolite particles to a film, and a method with an apparent specific gravity of 0.1 to 0.2 g/cm^3
A polypropylene stretched film with improved transparency, slipperiness, and anti-blocking properties by adding finely powdered silica with a specific surface area of 150 m^2/g or less (Japanese Patent Publication No. 63-58)
No. 170), etc. have been proposed. Problems to be Solved by the Invention Conventionally, amorphous silica has been widely used as an anti-blocking agent for resin films because resin films containing amorphous silica have anti-blocking properties. However, dispersibility may not be sufficient or film defects such as fish eyes and voids may occur. Further improvement is desired. The reason why the anti-blocking properties of the film are improved by adding amorphous silica is that the amorphous silica particles are distributed on or near the film surface and form gaps between the film surfaces. However, when the films are rubbed together, the abrasive action of amorphous silica causes scratches on the film surface, which is a major problem. In particular, it has been observed that amorphous silica with higher anti-blocking performance tends to cause scratches on the film surface more easily. According to research conducted by the present inventors, there is a relationship between the specific surface area and surface hardness of amorphous silica: the smaller the specific surface area, the smaller the Mohs hardness, and the larger the specific surface area, the smaller the Mohs hardness. There is a rule of thumb that particles with a large specific surface area have a glass shard-like appearance and sharp edges. This is because in amorphous silica, which has a large specific surface area, the soluble silicic acid component has an extremely fine particle size (herein, this particle size is referred to as the elementary particle size) when liberated in the form of silicic acid. This seems to be due to the fact that these elementary particles solidly coagulate to form gel-like particles. However, depending on the resin film, A
Due to the balance between B properties and film transparency, amorphous silica with a relatively high specific surface area must be used, which may cause problems such as abrasion and damage to equipment when manufacturing resin films. This method involves many problems such as scratches on the film surface when the obtained product films are rubbed together, which impairs the commercial value of the product.
Amorphous silica is still not satisfactory as an anti-blocking agent for resin films. [0009] Furthermore, since the amorphous silica used for the above purpose is a bulky fine powder particle with a small apparent specific gravity, it is difficult to handle due to its dustiness and is bulky, so it cannot be incorporated into resins. However, processability and dispersibility are also unsatisfactory. [0010] Therefore, the object of the present invention is to improve handling properties,
This product provides an amorphous silica filler that has excellent processability and dispersibility, and reduces wear and tear on equipment, etc., and also improves anti-blocking properties (AB properties) of resin films.
An amorphous silica-based anti-blocking agent for resin films that has excellent dispersibility, transparency, and scratch resistance that does not cause scratches on the product film surface when the films are rubbed together, and the same. The present invention provides a thermoplastic resin film using. [Means for Solving the Problems] According to the present invention, the average primary particle diameter (D1) measured by scanning electron microscopy is 100 to 270 nm, and the apparent specific gravity (JIS K6220.6
．． 8 method) is 0.24 to 0.55 g/cm^3, B
ET method specific surface area is 200 to 500 m^2/g,
Silica elementary particle diameter (D0
) is 5 to 15 nm, and [average primary particle diameter (D1)
The present invention provides an amorphous silica filler characterized in that the degree of agglomeration (DA) defined as the ratio: ]÷[silica elementary particle diameter (D0)] is in the range of 10 to 50. According to the present invention, there is also provided a thermoplastic resin film containing the above amorphous silica as an anti-blocking agent in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the thermoplastic resin. [Operation] In this specification, various particle sizes of amorphous silica are mentioned, and their measurement methods and significance are as follows. BET method specific surface area (m^2/g) is SA
, where the elementary particle diameter (nm) is D, the silica elementary particle diameter (D
0) is calculated from the formula SA=2727÷D. The specific surface area of the amorphous silica particles depends on the minimum basic particle size, ie, the elementary particle size, when the amorphous silica particles are precipitated as free silicic acid. These amorphous silica elementary particles are essentially spherical, and do not exist alone and cannot be confirmed with a normal electron microscope. Average primary particle diameter (D1
): Obtain the actual particle size from a scanning electron micrograph of amorphous silica and calculate its number average value. This is the minimum particle size of amorphous silica, which is composed of agglomerates or aggregates of elementary particles and can be detected using an electron microscope. Secondary particle diameter (D2): This is the volume-based median diameter of amorphous silica measured by the Coulter counter method. This is the particle size when amorphous silica, which is made up of aggregates of primary particles, actually behaves as powder particles. The amorphous silica of the present invention has a BET specific surface area in the range of 200 to 500 m^2/g, an average primary particle diameter (D1) in the range of 100 to 270 nm, and has the formula D1/ Agglomeration defined by D0
A distinctive feature is that the degree of oxidation (DA) is in the range of 10 to 50. [0015] In the present invention, the BET method specific surface area is 200
The specific surface area is specified to be from 500 m^2/g to 500 m^2/g because if the specific surface area is less than 200 m^2/g, anti-blocking properties will be poor and film forming defects such as fish eyes and voids will occur. On the other hand, if the specific surface area exceeds 500 m^2/g, the haze of the film will increase, the gloss will decrease, and transparency will be easily impaired, the scratch resistance of the film will increase, and it will be difficult to perform post-processing of powder, etc. However, it is difficult to define the average primary particle diameter within the scope of the present invention. Of course, the BET method specific surface area is 200 to 5.
Amorphous silica in the range of 00m^2/g is known, but in the present invention, the degree of agglomeration (D
A) is in the range of 10 to 50 and the average primary particle diameter (D1
) is in the range of 100 to 270 nm. FIG. 1 is a scanning electron micrograph showing the particle structure of the amorphous silica used in the present invention. From this photograph, it can be seen that the amorphous silica used in the present invention has an average primary particle diameter of 10
It can be seen that the particle size is 0 to 270 nm, the appearance of the particle shape is clear and the particle structure is constant, and the particle size distribution of the primary particles is also uniform. In addition, the silica elementary particles may be particularly finer than those of the present invention, or due to differences in the manufacturing method, they cannot be observed as so-called single particles under an ordinary electron microscope, and are instead a continuous, uniform gel body (
(see Figure 2), or discontinuities with unclear cohesion (see Figure 3).
It has a particle structure that is significantly different from conventional amorphous silica, such as those observed as silica. According to the present invention, the degree of agglomeration (DA
) and the average primary particle diameter (D1) within the above ranges, it is possible to significantly improve the scratch resistance when the film is rubbed together while maintaining the anti-blocking properties of the film at an excellent level. This fact will become immediately clear by referring to Examples and Comparative Examples described later. An important feature of the amorphous silica used in the present invention is that the apparent specific gravity (JIS K6220.6.8 method) is in the range of 0.24 to 0.55 g/cm^3. Amorphous silica with a large apparent specific gravity is known to have a coarse primary particle size (precipitated amorphous silica), while amorphous silica with a fine primary particle size has a structure of 0.2
Although the amorphous silica of the present invention has an apparent specific gravity smaller than g/cm^3, it is denser than the conventional precipitated amorphous silica and has an apparent specific gravity almost comparable to the gel-method amorphous silica. It's something you have. Since the amorphous silica used in the present invention is dense, it prevents dusting and has excellent handling properties.It is easy to blend into resin, knead, etc., and has excellent processability. This has the great advantage that it does not easily fly up into the atmosphere, so there is no possibility of dust scattering and deteriorating the working environment. [0021] The amorphous silica of the present invention has a small degree of agglomeration of primary particles, has a secondary particle diameter in the range of 1 to 5 μm by Coulter-Counter method, and has excellent dispersibility in resin. There is. In addition, it produces fewer fish eyes and voids during film formation, and has particularly excellent appearance characteristics when made into a film. Furthermore, in connection with the above-mentioned primary particle structure, it has a relatively large BET method specific surface area.
An additional feature is that it has a low oil absorption of between 120 ml/100 g. Generally speaking, it is easier to blend fillers and pigments into resins because the smaller the specific surface area, the better the surface wettability, and the larger the apparent specific gravity, the smaller the volume of the material to be filled. is known to improve. Since the amorphous silica filler of the present invention has a large apparent specific gravity and a low oil absorption, it can be blended into a resin and homogeneously dispersed therein. Preferred embodiments of the invention (Amorphous silica filler) The amorphous silica according to the present invention has an average primary particle diameter (scanning electron microscopy) of 100 to 270 nm, The average secondary particle diameter by method is 1 to 5 μm, preferably 1.5 to 4.5 μm, particularly preferably 1.8 μm.
The apparent specific gravity (JIS K6220
．． 6.8 method) is 0.24 to 0.55 g/cm^3,
Preferably it is 0.27 to 0.5 g/cm^3, particularly preferably 0.3 to 0.45 g/cm^3, and the oil absorption amount (JISK5105 method) is 50 to 120 ml/10
in the range of 0g, preferably 100ml/100
g or less, particularly preferably 80 ml/100 g or less, and has a BET method specific surface area (SA) of 200 to 500
m^2/g, and [average primary particle diameter (D1)] ÷ [
The degree of agglomeration (DA) defined as the ratio of the silica elementary particle diameter (D0) is 10 to 50, preferably 15
The range is from 20 to 45, particularly preferably from 20 to 40. When using the amorphous silica of the present invention as an anti-blocking agent for resins, other compounding agents such as lubricants, antistatic agents, plasticizers, nucleating agents, antifogging agents,
Organic components such as ultraviolet absorbers, antioxidants, insect repellents, antibacterial agents, fragrances, colorants, and medicinal ingredients may be supported or incorporated during resin molding. Furthermore, this amorphous silica can also be used in combination with other inorganic fillers. Also,
This filler may be surface-treated in advance with various metal soaps, waxes, resins, surfactants, lubricants, various coupling agents, inorganic oxides, etc., including the above-mentioned organic components. [0025] The organic and inorganic components used for such supporting or compounding and surface treatment are 0.00% per amorphous silica.
It is preferably in the range of 1 to 30% by weight, particularly 1 to 10% by weight. (Manufacturing method) The amorphous silica used in the present invention is produced by a method that is not limited to the following, but is positioned between the conventional gel method and precipitation method, and more specifically, acid silicate sol. It is produced by reacting sodium silicate with an aqueous salt solution under specific conditions. First, in producing the amorphous silica of the present invention, a considerable amount of the silica component to be subjected to the reaction is prepared in advance at a pH of 0.2 to 2.5, and the Si
It is preferable to prepare an acidic silica sol with a silica concentration of 3 to 20% by weight as O2. This acidic silica sol is prepared by adding 10% of the sodium silicate aqueous solution equivalent to 20 to 70% of the total weight of the sodium silicate.
The mixture is poured into a 60% by weight aqueous solution of hydrochloric acid or sulfuric acid while stirring, and the pH at the end of the reaction is adjusted to be within the above-mentioned range. Next, the remaining sodium silicate aqueous solution is added to an aqueous sodium silicate solution in which salt has been dissolved so that the amount becomes 10 to 300% by weight of the SiO2 equivalent amount under stirring at a temperature of 5 to 90°C. By adding this acidic silica sol to the solution, the silica hydrogel of the present invention can be obtained. Note that the pH at the end of the above reaction is
It is important to stir sufficiently so that the ratio is 5 to 8, preferably 6 to 7. [0028] The reaction method for preparing the silica hydrogel of the present invention is not necessarily limited to the above method; the above acidic silica sol is prepared, and 10 to 300% by weight of common salt equivalent to SiO2 is co-existed therein. While I was letting
The remaining sodium silicate aqueous solution may be added to maintain the pH within the range of 5 to 8 at the end of the reaction. The product is then filtered and washed with water using a conventional method, dried at a temperature of 120 to 400°C, and classified as necessary to obtain the product of the present invention. Note that the amorphous silica obtained by the present invention is amorphous silica whose content as SiO2 is in the range of 90 to 96% by weight, preferably 91 to 95% by weight on a dry basis at 150°C. [0029] The amorphous silica filler used in the present invention is produced by the above method, but the amorphous silica of the present invention is obtained by neutralizing acidic silica sol or by salting out the amorphous silica. If precipitated silica and amorphous silica derived from neutralization of sodium silicate are distinguished from gel silica, it can be said that precipitated silica and gel silica coexist. Of course, precipitated silica and gel silica are generally mixed in elementary particle size, but one or both silicas are used as core particles, and the surface of the core particle is coated with the other silica component, such as precipitated silica or gel silica. It will be clear to those skilled in the art that the gel-processed silica can have a composite particle structure in which it is present as a shell. (Applications) The amorphous silica of the present invention utilizes the above-mentioned properties to be used in various thermoplastic resins, such as propylene homopolymers as crystalline propylene copolymers, ethylene-propylene copolymers, low Olefin resins such as -, medium-, high-density or linear low-density polyethylene, ionically crosslinked olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-acrylic acid ester copolymers, polyethylene terephthalate thermoplastic polyester such as polybutylene terephthalate, 6-nylon, 6
, 6-nylon, 6,8-nylon, and other polyamide resins, vinyl chloride, vinylidene chloride, and other chlorine-containing resins, polycarbonates, polysulfones, and other resin molding materials such as various stretched films. It can be used to impart transparency, slip properties, and anti-blocking properties to products. For this purpose, the amorphous silica of the present invention is 0.01 to 1 part by weight per 100 parts by weight of thermoplastic resin.
It can be blended in an amount of 0 parts by weight, especially 1 to 5 parts by weight. Furthermore, the amorphous silica of the present invention can be used for various purposes by being blended with various paints, adhesives, and coating resin compositions, and can also be used in pharmaceuticals, foods, agricultural chemicals,
It can be added as a filler to insecticides and the like. EXAMPLES The present invention will be specifically explained with the following examples. In addition, in the present invention, the physical property test of amorphous silica and the evaluation test of the film were carried out by the following methods. BET method specific surface area Automatic BET specific surface area measuring device (manufactured by CARLO-ERBA, Sorptomatic Series 1800
) to determine the amount of nitrogen gas adsorbed in a monomolecular layer on the sample surface Vm [cc/g], and specific surface area (SA) = 4.
The BET specific surface area is calculated from 35×Vm [m^2/g]. Average secondary particle size (median diameter) The particle size determined from the 50% point of the volume distribution of the cumulative particle size curve obtained by the Coulter Counter method (TA-type, manufactured by Coaltar Electronics, USA). say. Primary particle size Scanning electron microscope WET manufactured by Akashi Beam Technology
- Using a SEM (WS-250), the average primary particle diameter was determined by arithmetic averaging of each particle diameter (nm) in the selected area image. Elementary particle diameter BET specific surface area SA (m^2/g) and elementary particle diameter D (nm
) is between R. K. It is known that the following relationship exists according to Iler*, and D (nm) is calculated from the relational expression SA=2727/D. *Ralp K. Iler, THe Colloid
Chemistry of Silica and
Silicates, Corne-ll Univ.
The oil absorption was determined based on the JIS K 5101-19 method of oil absorption pigment test method published by ersity Press (1955). pH value The pH value was determined based on the JIS K 5101-24A method for testing pigments. JIS K 6220.6. Test method for compounding agents for apparent specific gravity rubber.
8, the apparent specific gravity [g/cm^3] was determined. [0034] Unstretched polypropylene film (C-PP
Film) Creation Crystalline propylene polymers were propylene homopolymer (melt fluororate MFR = 1.8 g/10 minutes, isotactic index I.I. = 96.0) and ethylene-propylene random copolymer ( Melt fluorate MFR = 6.5 g/10 min, Isotactic index I.I. = 97.0, Ethylene content = 4.0 mol%, DSC melting point according to ASTM D-3417 = 14
C-PP films were obtained using two types of C-PP films (0°C) under the following conditions. Propylene polymer 100
Anti-blocking agent (hereinafter referred to as AB agent)
As a result, 0.15 parts of amorphous silica powder was added. At the same time, 0.15 part of 2.6 di-tert-butyl p-cresol and 0.1 part of calcium stearate were added as antioxidants, and mixed for minutes at 1000 rpm using a Henshil mixer. Next, the mixture was melt-mixed at 230° C. using a 65 mmφ single-screw extruder to form pellets. Using this pellet, T
An unstretched film (film sample F-1) with a thickness of 25μ was produced at 230°C using a 35mmφ extruder with a die.
) was obtained. [0035] Biaxially oriented polypropylene film (O-P
P film) Creation Propylene homopolymer (melt fluororate MFR = 1.8 g/10 minutes, isotactic index I.I. = 96.0) 100 as the crystalline propylene polymer
0.15 parts of amorphous silica powder was added as an AB agent. At the same time, 0.15 part of 2.6 di-tert-butyl para-cresol and 0.1 part of calcium stearate were added as antioxidants, and
Mixed for minutes at rpm. Next, the mixture was melt-mixed at 230° C. using a 65 mmφ single-screw extruder to form pellets. Using this pellet, a sheet-like film having a thickness of 1250 .mu.m was obtained at 230 DEG C. using a 35 mm.phi. extruder equipped with a T-shaped die. Using a 115mmφ biaxial stretch molding machine,
The film was stretched 5 times in the machine direction at 5 DEG C. and then 10 times in the transverse direction at 170 DEG C. in a tenter oven to obtain a biaxially stretched film (film sample F-2) having a thickness of 25 .mu.m. Preparation of nylon film (O-NY film) 6 - 94 parts of nylon powder (particle size 300 mesh or less, specific gravity = 1.14, melting point = 220°C), 5 parts of amorphous silica powder as an AB agent. Part was added. At the same time, 1 part of ethylene bisstearamide was added as a dispersant, and mixed for 3 minutes at 1000 rpm using a Henshil mixer. The resulting mixture was then melt-mixed at 260° C. using a 65 mmφ single screw extruder to obtain master pellets containing 5 parts of AB agent. Two parts of this master pellet and 98 parts of 6-nylon pellets to which no AB agent was added were mixed to form pellets with an added amount of AB agent of 0.1 part. Next, this mixed pellet was melt-extruded using a 35 mmφ extruder equipped with a T-shaped die, and solidified on a cooling roll at 40° C. to obtain an unstretched film with a thickness of 140 μm. This film is 11
Using a 5 mmφ biaxial stretching molding machine, the film was simultaneously biaxially stretched 3 times in length and width at a stretching temperature of 120°C, and then heat set at 190°C to produce a biaxially stretched film with a thickness of 15 μm (film sample F-3). I got it. (11) Appearance of the film Fish eyes or voids observed on the surface of the film having a size of 20 cm x 20 cm were observed with the naked eye and evaluated according to the following criteria. ◎: No fish eyes or voids are observed. ○: About 10 fish eyes or voids in the entire film
% or less. △: Approximately 50 fish eyes or voids in the entire film
%. x: Fish eyes or voids are very numerous and cover approximately 50% or more of the entire film. (12) Scratch resistance on the film surface The rolled film (200 m/roll) after film formation was rewound three times at a speed of about 20 m/min and evaluated according to the following criteria. ◯: The degree of scratches is very slight or does not occur at all. △: Occurrence of scratches is clearly observed, but it does not extend to the whole area. ×: There are so many scratches that it is practically unusable. (13) Haze (%) of film The degree of haze was measured according to the method of ASTM-D 1003-61 using a direct-reading haze meter manufactured by Suga Test Instruments. (13) Static friction coefficient The static friction coefficient (μs) and the dynamic friction coefficient (μd) were measured according to the method of ASTM-D 1894 using a slip tester manufactured by Nippon Rigaku Kogyo. The measurement conditions were as follows. Film sample F-1: 23°C, 40°C x 3 days film sample F-2: 40°C x 1 day film sample F-
3: RH (relative humidity) 65%, RH 85% (14) Blocking resistance (AB property: g/cm) Layer two films so that the contact area is 10cm^2 and place them between two glass plates. Sandwich and place an overweight of 50 g/cm^2 at 40°C for 24 hours. After being left standing, the maximum load at which the upper layer film and lower layer film peel off is measured using a friction coefficient measuring device manufactured by Toyo Seiki. Film sample F-1: 50°C x 7 days film sample
F-2: 50°C x 30 days Example 1 Commercially available sodium silicate solution (specific gravity 1.29, composition 3.3S
When preparing amorphous silica using a 13% concentration sulfuric acid solution (iO2.Na2O.nH2O), an acidic silica sol was prepared in advance using half of the sodium silicate solution in the following manner. A sodium silicate solution containing 50% of the total reaction amount in a sulfuric acid solution was heated to a temperature below 20°C while stirring.
The acidic silica sol with a pH of 0.7 was obtained by pouring the mixture over a period of time. Next, SiO2:N was added to the remaining 50% sodium silicate solution.
Add NaCl so that the weight ratio of aCl is 1:1,
The acidic silica sol solution was added thereto over 5 hours while stirring. The obtained silica slurry has a pH of 6.5, and after filtering and washing, the silica cake has a pH of 110 to 3.
Dry at 50℃, crush and classify to obtain an average secondary particle size of 1.8.
obtain amorphous silica of μm, 2.7 μm and 3.5 μm,
Samples 1, 2, and 3 were used, respectively. The physical properties of the obtained amorphous silica are shown in Table 1, the evaluation of sample F-1 of the resin film using it as an AB agent is shown in Tables 2 and 3, and the evaluation of sample F-2 is shown in Table 4. Sample F
The evaluations for -3 are shown in Table 5. The obtained amorphous silica was 93.5% by weight as SiO2 on a dry basis at 150°C. Example 2 An acidic silica sol was prepared in the same manner as in Example 1 using hydrochloric acid as the mineral acid, and amorphous silica was obtained using this sol in the following manner. In hydrochloric acid solution (concentration 14%, specific gravity 1.
A sodium silicate solution containing 33% of the total reaction amount as a phase was added to 07) at a temperature of 20° C. or lower for 1.5 hours while stirring to obtain an acidic silica sol having a pH of 0.3. Next, NaCl was added to the remaining 67% sodium silicate solution so that the weight ratio of SiO2:NaCl was 1:0.15.
heated to ℃. The acidic silica sol solution was added thereto over 4 hours while stirring. The obtained silica slurry is
Amorphous silica having a pH of 7.2 and an average secondary particle diameter of 2.18 μm was then obtained in the same manner as in Example 1, which was designated as Sample 4. The physical properties of the obtained amorphous silica are shown in Table 1.
The evaluation of resin film sample F-1 using this as an AB agent is shown in Tables 2 and 3, the evaluation of sample F-2 is shown in Table 4, and the evaluation of sample F-3 is shown in Table 5. . The obtained amorphous silica was 91.4% by weight as SiO2 on a dry basis at 150°C. Example 3 In the same manner as in Example 1, an acidic silica sol was prepared using hydrochloric acid as the mineral acid, and amorphous silica was obtained using this sol in the following manner. In hydrochloric acid solution (concentration 14%, specific gravity 1.07)
Add 20% sodium silicate solution as a phase to 67% of the total reaction amount.
℃ or less for 2.5 hours while stirring, and
An acidic silica sol of H1.4 was obtained. Then the remaining 33
% sodium silicate solution so that the weight ratio of SiO2:NaCl was 1:2.5. The acidic silica sol solution was added thereto over 5 hours while stirring. The obtained silica slurry had a pH of 7.1, and was then treated in the same manner as in Example 1 to obtain amorphous silica having an average secondary particle diameter of 2.8 μm, which was designated as Sample 5. The physical properties of the obtained amorphous silica are shown in Table 1, the evaluation of sample F-1 of the resin film using it as an AB agent is shown in Tables 2 and 3, and the evaluation of sample F-2 is shown in Table 4. Sample F
The evaluations for -3 are shown in Table 5. The obtained amorphous silica was 94.6% by weight as SiO2 on a dry basis at 150°C. Example 4 In preparing amorphous silica, a concentrated acidic silica sol solution was continuously obtained by the following method, and then a sodium silicate solution containing NaCl and an acidic silica sol solution were heated. Amorphous silica was obtained by continuous contact reaction. Sodium silicate solution and sulfuric acid solution (concentration 40%,
An acidic silica sol is prepared by the following method using a specific gravity of 1.25). Using a device that can continuously supply a sodium silicate solution and a sulfuric acid solution corresponding to 50% of the total reaction amount at a temperature of 25°C or lower at a volume ratio of 4:1, the mixture is rapidly sheared and stirred. Continuously acidic silica sol (pH 2
．． 1) is obtained. On the other hand, add Na to the remaining 50% sodium silicate solution so that the weight ratio of SiO2:NaCl is 1:2.
Amorphous silica was obtained by reacting at 60 DEG C. under rapid shear stirring while continuously feeding the sodium silicate solution to which Cl was added and the acidic silica sol solution prepared by the above method. Next, in the same manner as in Example 1, amorphous silica (sample 6) with an average secondary particle size of 2.2 μm and amorphous silica (sample 6) with an average secondary particle size of 4.1 μm were prepared.
Sample 7) was obtained. The physical properties of the amorphous silica obtained in the same manner are shown in Table 1, and the evaluation of the resin film sample F-1 using it as the AB agent is shown in Tables 2 and 3.
The evaluation for sample F-2 is shown in Table 4, and the evaluation for sample F-3 is shown in Table 5. The obtained amorphous silica had a SiO2 content of 92.8% by weight on a dry basis at 150°C. Comparative Example 1 A film test and evaluation was carried out in the same manner as in the example using sample H1 of commercially available product A (manufactured by Mizusawa Chemical Industry Co., Ltd.) having an average secondary particle diameter of 1.7 μm as amorphous silica. Comparative Example 2 A film test evaluation was conducted in the same manner as in the example using sample H2 of commercially available product B (manufactured by Fuji Davison) having an average secondary particle diameter of 2.1 μm as amorphous silica. Comparative Example 3 A film test evaluation was conducted in the same manner as in the example using sample H3 of commercial product B (manufactured by Fuji Davison) having an average secondary particle diameter of 3.1 μm as amorphous silica. For Comparative Examples 1, 2, and 3, the physical properties of the obtained amorphous silica are shown in Table 1 in the same manner as in the Examples, and the evaluation of the resin film sample F-1 using the same as the AB agent is shown in Table 2. , Table 3
Table 4 shows the evaluation of sample F-2.
The evaluations for F-3 are shown in Table 5. [Table 1] Physical properties of various amorphous silicas Example 1 1
1 2 3 4
4 Sample
1 2 3 4
5 6 7 pH
7.14 7.15 7.
14 7.50 7.8 6.7 6
．． 72 Oil absorption amount (ml/100g) 86
83 76 92
98 70 63 Specific surface area (m^2
/g) 370 376 386
315 280 465 46
5 Apparent specific gravity (g/cm3) 0.321
0.342 0.376 0.286 0.2
72 0.43 0.523 Average secondary particle diameter (
μm) 1.8 2.7 3.5 2
．． 1 2.8 2.2 4.1
Average primary particle size: 180 18
0 180 150 200
250 250 D1 (nm) Elementary particle diameter: D0 (nm) 7.4 7.
3 7.1 8.7 9.7
5.9 5.9 Degree of agglomeration: 24.4 24.8 25.5 1
7.3 20.5 42.7 42.7
(D1/D0=DA) Comparative example 1
2 3 Sample
H1 H2
H3 pH
6.98 7.96 3.90
Oil absorption amount (ml/100g) 16
2 263 106 Specific surface area (m^2/g) 55 288
704 Apparent specific gravity (g/cm^3
) 0.188 0.138 0.506
Average secondary particle diameter (μm) 1.7 2
．． 1 3.1 Average primary particle size:
80 9.8* ∞
D1 (nm) Elementary particle diameter: D0 (nm) 49.6 9
．． 4 3.8 Degree of agglomeration: 1.61 1.04 ∞
(D1/D0=DA) *Average value of remaining particles excluding coarse particles seen in Figure 2 [Table 2] Evaluation test of film sample F-1 Example 1
1 1 2 3
4 4 Sample
1 2 3 4
5 6 7 Haze (%)
2.5 2.6 2.
8 2.5 2.7 2.5 3
．． 2 Gross (%) 97
95 95 96 9
5 96 93 Slip property* Static/
0.65 0.68 0.70
0.65 0.70 0.63 0.72
dynamic /0.5
1 /0.53 /0.55 /0.50 /
0.56 /0.50 /0.58 Slip property *2 static / 0.31 0.33
0.34 0.29 0.34 0.28
0.36 motion
/0.27 /0.29 /0.30 /0.
26 /0.30 /0.25 /0.32 Blocking resistance Good Good
Good Good Good Good Good
Gender (g/cm) *3

Scratch resistance
○ ○ △
○ ○ ○ ○ Film appearance ◎ ◎ ○
◎ ◎ ◎ ○
Comparative example 1 2
3 Sample
H1 H2 H3 Haze (
%) 2.5 2.7
2.9 Gross (%) 9
7 95 93 Slip property *1 Static / 0.60 0.65 0.6
8 motion /
0.50 /0.50 /0.55 Slip property *2 Static / 0.27 0.30 0.
33 motion
/0.24 /0.26 /0.29 Blocking resistance 0.25 Good Good
Gender (g/cm) *3
Scratch resistance
○ △ ×
Film appearance ×
× ◎ *1: 23℃ x 1 day, *2
: 40°C x 3 days, *3: 50°C x 7 days [Table 3] Evaluation test of film sample F-1 Example 1
1 1 2 3
4 4 Sample
1 2 3 4
5 6 7 Haze (%)
2.0 2.6 3.2
2.0 2.8 2.0 3.6
Gross (%) 11
0 100 96 110
100 110 97 Slip property *1 Static / 0.30 0.35
0.45 0.32 0.39 0.32
0.48
Dynamic /0.26 /0.32 /0.37
/0.27 /0.31 /0.27 /0.3
7 Slip property *2 Static / 0.13 0.
20 0.27 0.12 0.22
0.15 0.27
Dynamic /0.12 /0.18 /0.2
5 /0.11 /0.20 /0.14 /0.
25 Blocking resistance 1.25
1.00 0.36 1.26 0.95
1.15 0.32 Gender (g/cm) *3


Scratch resistance ○
○ △ ○ ○
○ △ Film appearance
◎ ◎ ○ ◎ ○
◎ ○ Comparative example
1 2 3
Sample H
1 H2 H3 Haze (%)
2.1 2.9 2.6
Gross (%) 1
20 100 96
Slip property *1 Static / 0.27 0.41
0.37
Dynamic /0.24 /0.32 /0.
32 Slip property *2 static / 0.12
0.12 0.24
Dynamic /0.11 /0.1
1 /0.23 Blocking resistance
2.95 1.26 1.29
Gender (g/cm) *3
Scratch resistance
○ △ ×
Film appearance ×
× ◎ *1: 23℃ x 1 day, *2
: 40°C x 3 days, *3: 50°C x 7 days [Table 4] Evaluation test of film sample F-2 Example 1
1 1 2 3
4 4 Sample
1 2 3 4
5 6 7 Haze (%)
1.0 1.1 1.3
1.0 1.3 1.0 1.4
Gross (%) 143
139 135 140 139
140 133 Slip property *1 Static/
0.52 0.51 0.48
0.52 0.51 0.52 0.45
dynamic /0.5
2 /0.50 /0.47 /0.52 /
0.50 /0.51 /0.43 Blocking resistance Good Good Good
Good Good Good (g/
cm) *2

Scratch resistance
○ ○ △ ○
○ ○ △ Film appearance
◎ ◎ ○ ◎
○ ◎ ○ Comparative example
1 2
3 Sample
H1 H2 H3 Haze (%) 1.1 1.3
1.4 Gross (%)
143 135 133
Slip property *1 Static / 0.58
0.51 0.51
dynamic /0.55 /0.5
0 /0.49 Blocking resistance
0.13 0.05 Good
Gender (g/cm) *2
Scratch resistance
○ △ ×
Film appearance ◎
× × *1: 40℃ x 1 day, *
2: 50℃ x 30 days
0053
[Table 5] Evaluation test of film sample F-3 Example 1
1 1 2 3
4 4 Sample
1 2 3 4
5 6 7 Haze (%)
1.6 2.1 2.
8 1.7 2.2 1.7 2
．． 8 Gross (%) 143
139 135 140 13
9 145 135 Slip property *1 Static/
0.36 0.42 0.50
0.35 0.51 0.36 0.53
dynamic /0.35
/0.40 /0.45 /0.35 /0
．． 47 /0.35 /0.44 Slip property *2
Still / 0.46 0.51 0.57
0.45 0.58 0.50 0.55
Dynamic /0.
43 /0.47 /0.47 /0.42
/0.50 0.48 /0.47 Scratch resistance
○ ○ △
○ ○ ○ △
Film appearance ◎ ◎
○ ◎ ○ ◎
○ Comparative example 1
2 3 Sample
H1 H2 H3
Haze (%) 5.0
2.4 2.2 Gross (%) 152 140
135 Slip property *1 Static/
0.51 0.39 0.43
Dynamic /0
．． 40 /0.37 /0.40 Slip property *2 0.57 0.60 0.
68
/0.47 /0.55 /0.62
Scratch resistance ○
△ × Film appearance
○ × ×
*1: 24℃×R. H. 65%, *2: 25℃×R
．． H. [Effect of the invention] The amorphous silica according to the present invention has a BET
It is a dense silica with a specific surface area of 200 to 500 m2/g and an apparent specific gravity of 0.24 to 0.55 g/cm^3, and an oil absorption of 50 to 120 m2.
1/100g, and the degree of agglomeration (D1) defined by the ratio of the silica elementary particle diameter D0 calculated from the BET method specific surface area and the primary particle diameter D1 obtained from a scanning electron micrograph. /D0=DA) is in the range of 10 to 50, and conventional gel method silica (DA=∞)
It is amorphous silica with an approximately spherical external appearance and a particle structure that is significantly different from that of silica. For this reason, it is a filler with particularly excellent handling properties, processability, dispersibility, and abrasion resistance. [0055] When this filler is added to a resin as an anti-blocking agent, various drawbacks of conventional amorphous silica-based anti-blocking agents are eliminated, fish eyes and voids are not generated, and transparency and anti-blocking agents are improved. Blocking properties can be significantly improved. In particular, it is possible to obtain a resin film that is dense and has good handling and processability due to its particle shape, and has scratch resistance that does not cause any scratches on the film surface when the films are rubbed together. Furthermore, a thermoplastic resin film using this filler can be provided.

[Brief explanation of the drawing]

FIG. 1 is a scanning electron micrograph (magnification: 20,000 times) showing the particle structure of the amorphous silica filler of the present invention.

FIG. 2 is a scanning electron micrograph (magnification: 20,000 times) showing the particle structure of commercially available amorphous silica (Comparative Example 2).

FIG. 3 is a scanning electron micrograph (magnification: 20,000 times) showing the particle structure of commercially available amorphous silica (Comparative Example 3).

Claims (5)

[Claims] Claim 1: An average primary particle diameter (D1) measured by scanning electron microscopy of 100 to 270 nm, and an apparent specific gravity (J
ISK6220 method) is 0.24 to 0.55 g/cm^
3, the BET method specific surface area is 200 to 500 m^2/g
, and the silica elementary particle diameter (D0) calculated from the BET method specific surface area is 5 to 15 nm, and is defined as the ratio of [average primary particle diameter (D1)] ÷ [silica elementary particle diameter (D0)] An amorphous silica filler characterized by having a degree of agglomeration (DA) in the range of 10 to 50. 2. The amorphous silica filler according to claim 1, which has an average secondary particle diameter of 1 to 5 μm as determined by the Coulter-Counter method. [Claim 3] Oil absorption (JISK5101 method) is 50
2. The amorphous silica filler according to claim 1, wherein the amount is 120 ml/100 g. 4. An anti-blocking agent for resin films, comprising the amorphous silica according to claim 1. 5. A thermoplastic resin film, characterized in that the anti-blocking agent according to claim 4 is added in an amount of 0.01 to 5 parts by weight per 100 parts by weight of the thermoplastic resin.