JPH10330112A - Bellows-like inorganic particle and synthetic resin composition containing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain inorganic particles capable of imparting a good light-diffusing effect without lowering total light transmittance, when a synthetic resin is compounded with the particles and subsequently processed into a sheet, and capable of imparting good blocking resistance and abrasion resistance, when added to films or fibers, by selecting the inorganic particles whose cross sections vertical to the laminated direction are substantially quadrilateral and which have physical properties such as a specific particle diameter. SOLUTION: This bellows-like inorganic particle whose cross section vertical to the laminated direction is substantially quadrilateral and which has the following requirements: 0.6<=(b)/(a)<=1.5, 0.8<=(c)/(a)<=5.0, (n)>=3, (S)<=1 and 0>=(DP1-DP3)/DP2<=1. Therein, (a) is the average length (μm) of an arbitrary one side of the quadrilateral cross section vertical to the laminated direction; (b) is an average particle length (μm) vertical to the side of (a) in the same cross section; (c) is an average particle length (μm) in the laminated direction; (n) is the average number of laminated layers; DP1-DP3 are particle diameters at total weights of 25%, 50% and 75%, respectively, started from the side of a large particle diameter in a particle size distribution; S is a relative standard deviation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to bellows-like inorganic particles having a specific shape and particle size, and a synthetic resin composition containing the particles. More specifically, polyolefins, synthetic resin films of polyester and the like, have excellent antiblocking ability in synthetic fibers and the like, and are excellent in that, for example, a light diffusion sheet using an acrylic resin exhibits characteristic diffused light. The present invention relates to bellows-like inorganic particles imparting physical properties and a synthetic resin composition containing the same.

[0002]

2. Description of the Related Art Synthetic resins are widely used for various industrial purposes. Above all, acrylic resins such as methyl methacrylate, or polyesters, especially polyethylene terephthalate (hereinafter referred to as PET) have excellent physical and chemical properties, such as molded sheets, fibers, films, and other molded products. Widely used as. For example, in the case of acrylic resin, a lighting cover as a light diffusion sheet,
Used as a member for light diffusion plates for transmissive displays, lighting signs, etc. In the case of polyester, for example, in the field of polyester films, magnetic tapes such as audio tapes and video tapes, condensers, photographs, packaging, OHPs Used for etc.

[0003] The light diffusing sheet is required to have a performance in which an image of a light source is difficult to see (hiding property) and a property of scattering light at a wide angle (light diffusing property) despite high light transmissivity. In order to satisfy these performances, as a conventional production method, a light diffusing agent such as titanium oxide or silica is mixed with a binder, and this liquid material is applied to the surface of a light-transmitting synthetic resin plate such as an acrylic resin plate. , Drying, solidifying, forming a light diffusion layer on one side, manufacturing using a polymer having a different refractive index, and applying fine irregularities to the surface of the sheet-like material. As a method of providing a diffusion layer, or a production method in which a light diffusion layer is not exposed on the surface, a method of mixing and dispersing inorganic light diffusing agent particles such as titanium oxide, barium sulfate, talc, silica, and calcium carbonate in an acrylic resin, or the like is available. (JP-A-53-9835).
4, JP-A-57-155245, JP-A-59-1665
51, JP-A-9-31288, etc.).

However, in the former method, since the light diffusion layer is exposed on the surface of the manufactured sheet-like material, there is a concern that the light diffusion layer is stained or peeled off.
In addition, there is a disadvantage that light diffusion spots are easily generated and high technology is required to prevent light diffusion spots from occurring, and that productivity is lowered. Also in the latter method, for example, the inorganic light diffusing particles have a disadvantage that the cutting process is not easy in a sheet-like material containing a light diffusing agent having high hardness such as silica and glass beads. Even if a relatively low-hardness light diffusing agent is used, the naturally occurring raw ore is mechanically pulverized and classified to adjust the average particle size to a desired range, for example, in the case of heavy calcium carbonate, for example. Since the particle size distribution is wide, coarse particles are included, and the shape of each particle is non-uniform, a sufficient light diffusion effect cannot be expected by adding a small amount. Also, JP-A-9-3
Even in the case of the precipitated calcium carbonate having the shape specified in 1288, the balance between the concealing property and the light diffusing property is poor unless the calcium carbonate has a particle diameter of 1 μm or more, and 1 μm is used in order to enhance the smoothness of the surface of the sheet. Even if an attempt is made to use particles having a particle size smaller than the above, the total light transmittance is reduced, and on the other hand, the light diffusivity is poor. Therefore, when the light diffusing sheet is heat-formed and partially stretched when used for a lighting device, a signboard, or the like, the above-described inconvenience may occur. In addition, even if these particles are treated with any organic substance on the surface of the particles, only similar results can be obtained because there is no change in basic dispersibility and shape.

On the other hand, in a polyester film,
The slipperiness and abrasion resistance are major factors that affect the workability of the film manufacturing process and the working process in each application, and the quality of the product. When these slipperiness and abrasion resistance are insufficient, for example, when a magnetic layer is applied to the surface of a polyester film and used as a magnetic tape, friction between the coating roll and the film surface during application of the magnetic layer is intense. The surface of the film is also severely abraded by wrinkles, and in extreme cases, wrinkles, abrasions and the like are generated on the film surface. Also, even after slitting the film after applying the magnetic layer and processing it into audio, video, computer tape, etc., when pulling out from reels or cassettes, winding up and other operations, many guide parts, playback heads etc. Abrasion occurs significantly between
Distortion is generated, and white powder-like substances are precipitated due to scraping of the polyester film surface, etc., and often cause a large loss of a magnetic recording signal, that is, a dropout.

Conventionally, as a method for lowering the friction coefficient of polyester, there have been proposed a number of methods for improving the surface lubricity of a molded article by adding inorganic fine particles to the polyester to give fine and appropriate irregularities on the surface of the molded article. And inorganic particles such as titanium oxide, silica, kaolin clay, and calcium carbonate are used. Particles that form irregularities on the surface of these polyester films generally have a greater effect of improving slipperiness as their size increases,
For precision applications such as magnetic tape, especially video tape,
Since the large particles themselves can cause defects such as dropouts, the unevenness of the film surface needs to be as fine as possible, and the appearance of particles having the function of simultaneously satisfying these contradictory characteristics is strong. Is desired.

However, conventionally used inorganic particles are insufficient in particle size control and particle dispersibility of titanium oxide, and insufficient in slipperiness due to fineness of silica. The abrasion of kaolin clay is large, and kaolin clay has a plate-like structure with a large aspect ratio (long diameter / thickness of the surface). The calcium carbonate used is also inherently strong in cohesion and tends to form secondary coarse particles in which a large number of primary particles are aggregated. Therefore, there is a problem to be improved as an antiblocking agent having both good blocking resistance and abrasion resistance. Contains.

[0008] Calcium carbonate has been described as well known,
Natural calcium limestone is mechanically pulverized and classified into various grades by mechanically pulverizing and classifying the natural limestone, and the so-called carbon dioxide gas method, which is once calcined to obtain quicklime, which is obtained by the reaction between the quicklime and water. It is roughly classified into precipitated calcium carbonate typified by a method obtained by passing carbon dioxide gas generated during firing to the obtained lime milk.

[0009] Among the calcium carbonates, the former heavy calcium carbonate has a feature that it can be produced relatively inexpensively, but it is impossible to completely classify coarse particles and fine particles by the current classification technology. In addition, heavy calcium carbonate having a certain degree of fineness cannot be produced by the current pulverizing and classifying technique, and is therefore unsuitable as an anti-blocking agent for a polyester film like the light diffusion sheet described above.

[0010] On the other hand, in the case of precipitated calcium carbonate, as described above, primary particles are produced as fine particles having a particle size of several μm.
Although it can be easily controlled up to a large particle diameter of m, it forms a coarse secondary aggregate with a large number of primary particles, and a great amount of energy is required to disperse it to the desired particle size distribution, In a method of pulverization and destruction, such as a sand grinder mill, which is employed as a method, the agglomerates are dispersed and the primary particles are destroyed at the same time, and the shape of the particles is impaired. Particles that are stable and smaller than the desired primary particle diameter and secondary agglomerated particles that are incompletely dispersed may coexist, resulting in a broad particle size distribution, which may be unsuitable as an antiblocking agent.

In order to improve these situations, reports have recently been made in JP-A-5-117443 and JP-A-7-266398. In the former, calcium carbonate having a specific particle size and a specific particle size is used. It is configured as an anti-blocking agent and does not mention the particle shape related to having better performance, and in the latter, the particle shape is close to regular hexahedron and the particle size distribution was specified in a narrow range Although it is composed of hexahedral calcium carbonate having a calcite structure, it is not clear why it must be hexahedral, and it does not come out of speculation. However, as shown in FIG. ) Is film 7
Only when it is located near the surface of the film, fine projections are only possible, and since most of the particles are buried in the film, an increase in the amount of addition cannot be avoided, and as shown in FIG. When the hexahedral particles 6 are located near the surface of the film 7 as a surface, the frictional resistance is expected to increase as compared with the case of dots and lines, and it is also expected that the particles will fall off during the running of the film. Therefore, it is difficult to say that the anti-blocking agent has a sufficient function.

[0012]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention relates to a synthetic resin such as an acrylic resin or a polyester, which has a characteristic particle shape when formed into a sheet. When a product is stretched, it imparts a good light diffusion effect without lowering the total light transmittance, and when it is made into a film or fiber, it has a good slip-preventing function while having a good fall-off prevention function. It is intended to provide bellows-like inorganic particles having good blocking resistance and abrasion resistance, such as retaining the properties, and a synthetic resin composition containing the particles.

[0013]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, the inorganic particles having a specific shape and a specific particle size have solved the above-mentioned problems, and have an anti-blocking property. It has been found that a synthetic resin composition having excellent properties and abrasion resistance can be provided, and the present invention has been completed. That is, a first aspect of the present invention is that the section perpendicular to the laminating direction is substantially a quadrilateral and the following requirement (1):
To (5). (1) 0.6 ≦ b1 / a ≦ 1.5 (2) 0.8 ≦ c / a ≦ 5.0 (3) n ≧ 3 (4) S ≦ 1 (5) 0 ≦ (DP1-DP3) / DP2 ≦ 1 where, a: average (μm) of arbitrarily determined length of one side of a quadrilateral of a cross section perpendicular to the laminating direction b: X of the same cross section with the side direction of a as the X axis Average length of particles in the Y-axis direction perpendicular to the axis (μm) c: Average of particle length in the Z-axis direction in the lamination direction perpendicular to the X-axis as the Z-axis (μm) n: Stack of layers Average number of layers DP1: Light transmission type particle size distribution analyzer (SA- manufactured by Shimadzu Corporation)
In the particle size distribution using CP3), the particle size (μm) at 25% of the cumulative weight calculated from the larger particle size side DP2: Light transmission type particle size distribution analyzer (Shimadzu SA-
In the particle size distribution using CP3), the particle size (μm) at 50% of the cumulative weight calculated from the larger particle size side DP3: Light transmission type particle size distribution analyzer (Shimadzu SA-
In the particle size distribution using CP3), the particle size (μm) at a cumulative weight of 75% calculated from the larger particle size side S: relative standard deviation ai: The average of the lengths (μ) of arbitrarily determined sides of a quadrilateral having a cross section perpendicular to the laminating direction of the individual bellows-like particles.
m) bi: average length (μm) of particles in the Y-axis direction perpendicular to the X-axis of the same cross-section, with the ai side direction of each bellow-like particle as the X-axis; ci: X-axis of each bellow-like particle The stacking direction perpendicular to
Average length of particles in the Z-axis direction as an axis (μm) DC1: Length of one side length of a cube (μm) showing the same value as the average value of the volume of individual bellows-like particles as a square prism

It should be noted that in the present invention, as shown in FIG. 1, the inorganic particles of the present invention are bellows-like particles having a layered shape and a substantially quadrangular cross section in the laminating direction. It is to be. Thereby, for example, even if the light diffusion sheet is heat-formed like a lighting fixture and partially stretched, the light diffusion effect does not decrease due to its unique shape, and blocking of a film typified by polyester. As for the prevention effect, as shown in FIG. 6, since the laminating surface of the bellows-like particles 8 is located near the surface of the film 7, many sides exhibit good blocking properties without increasing the friction coefficient, and A remarkable effect is exhibited, such as having a fall prevention function.

The requirements that the bellows-like particles must simultaneously satisfy are (1) the average a (μm) of an arbitrary length of one side of a quadrilateral having a cross section perpendicular to the laminating direction; Is the average length b (μm) of particles in the Y-axis direction perpendicular to the X-axis of the same cross section, ie, the ratio of the height of the base to the height of the quadrilateral having the side in the a-direction as the base. a (see FIG. 1) is 0.6 ≦ b / a ≦ 1.5, (2) the average c of the particle lengths in the Z-axis direction, where the Z-axis is the length of the base and the lamination direction perpendicular to the X-axis (Μm) (see FIG. 1) is 0.8 ≦ c /
a ≦ 5.0, (3) the number n of stacked layers in the stack (FIG. 3
N) = 3 and (4) S≤1, that is, the particle size of the bellows-like particles is uniform so as to satisfy the above expression.

When b / a is smaller than 0.6 or larger than 1.5, the particles approach the plate-like shape, which is not preferable, and must be in the above-mentioned range. is there. If c / a is out of the above range, it is not preferable for the same reason. If the thickness in the layer direction with respect to the side in the a direction, that is, c / a is smaller than 0.8, the bellows-like surface is perpendicular to the film stretching direction. However, if the value exceeds 5.0, particles may be damaged during heat molding of the sheet-like material.
It is preferably between 1 and 3, more preferably between 1 and 2.

When the number n of the layers is less than 3, the bellows-like effect is poor, and is preferably 5 or more. Similarly, the S value is obtained by calculating the average value of one side a of the quadrilateral having a cross section perpendicular to the laminating direction, the height b of the quadrilateral having the base as the base, the length c in the laminating direction, and the individual bellows-like particles. Represents the relative standard deviation of the length of one side of the cube showing the same value as the average value of the volume assumed as a quadratic prism and the DC1. The closer this value is to 0, the sharper the grain content is. But this S
If the value exceeds 1, the protrusions on the film surface become non-uniform, and in some cases, coarse particles are included, which is a problem. Therefore, this S value is preferably 0.6 or less, more preferably 0.4 or less. Furthermore, from the particle size distribution of such inorganic particles, 0 ≦ (DP1-DP3) /
It is necessary to satisfy the relationship of DP2 ≦ 1. (DP
If 1-DP3) / DP2 exceeds 1.0, it indicates that the content of the particle size is wide, and the smoothness of the surface of the sheet is impaired, and uniform projections cannot be formed on the film surface. This is a problem because of inconvenience, and is preferably 0.7 or less, more preferably 0.5 or less.

The cross section perpendicular to the laminating direction of the bellows-like particles is not particularly limited as long as it is substantially a quadrilateral, and the desired effect of the present invention is exhibited.
The ratio of the length b1 (μm) of the side in contact with one vertex of the side in the direction and the length b2 (μm) of the side in contact with another vertex of the side in the a direction of the quadrilateral with the length of the side in the a direction Are respectively 0.6 ≦ b1 / a and b2 / a ≦ 1.5, and more preferably, the respective ratios are 0.8 ≦ b1 / a and b2.
/A≦1.2, that is, a shape whose cross section perpendicular to the lamination direction is closer to a square is preferable (see FIG. 2). If the respective ratios are smaller than 0.6 or larger than 1.5, the shape becomes distant from the square, and the effect of the antiblocking agent as the expected side of the layer is reduced. Further, the average particle diameter DP2 of the bellows-like particles is not particularly limited and does not impair the effects of the present invention as long as the particle diameter is usually added to the synthetic resin, but is preferably 0.01 to 15 μm. It is more preferably between 0.05 and 3 μm, most preferably between 0.05 and 0.5 μm, which is fine and can maintain a good dispersion state. According to the fine particle side, the dispersibility of the particles may be hindered, and it is expected that the smoothness of the surface is impaired as the particles become larger.

The bellows-like inorganic particles having the above-mentioned shape and particle size can be produced by the following method, for example, in the case of precipitated calcium carbonate. As a production method generally called a solution method, a carbonate solution, for example, 0.1 to 3.0 mol of sodium carbonate, ammonium carbonate or the like is used.
l-l aqueous solution and a calcium salt solution, for example, 0.1-3.0 mol / l aqueous solution of calcium chloride, calcium nitrate or the like, or 0.001-2.0 mol / l of sodium hydroxide, for example, A buffer such as ammonia water is added, and the two are mixed under stirring to form bellows-like calcium carbonate particles. The reaction-terminated liquid is dehydrated and washed with water to give a bellows-like carbonate containing no impurities other than calcium carbonate. Calcium particles are obtained.

The amount of the bellows-like inorganic particles of the present invention contained in the synthetic resin varies depending on the type and use of the synthetic resin and cannot be specified unconditionally. For example, in the case of an acrylic resin sheet, the resin 100 0.0 parts by weight
The amount is suitably 5 to 15 parts by weight, preferably 0.5 to 6 parts by weight. In the case of a synthetic resin film, 0.005 to 3 parts by weight per 100 parts by weight of the resin is appropriate, and 0.01 to 1 part by weight. Parts by weight are preferred. The reason is that below the lower limit,
This is because the desired effect is insufficient due to the small content, and the accuracy of adding the compound to the synthetic resin to uniformly disperse is reduced. On the other hand, when the content exceeds the upper limit, the concealing property is increased and the light transmittance is increased. , The physical properties are not improved for the content, and the stretchability of a film or the like is also reduced.

The surface treatment of the bellows-like particles is not particularly limited, but is appropriately selected according to the usual use. Examples of the surface treating agent include saturated and unsaturated fatty acids such as lauric acid, palmitic acid, oleic acid, linoleic acid, stearic acid, and behenic acid; abietic acid, neoabietic acid, benzoic acid, cinnamic acid, and the like. Alicyclic, aromatic resin acids, alkyl sulfonic acids,
Sulfonic acid compounds exemplified by alkylbenzene sulfonic acid, etc .; sulfuric acid compounds exemplified by alkyl sulfuric acid, alkyl ether sulfuric acid, etc .; phosphoric acid compounds exemplified by alkyl phosphoric acid, alkyl ether phosphoric acid, etc .; methyl ester, ethyl ester, hexyl of these acids Esters such as esters, salts of alkali metals, ammonium, amines and the like; cellulose compounds exemplified by hydroxyethyl cellulose, carboxymethyl cellulose, etc .; coupling agents exemplified by titanate coupling agents, silane coupling agents, etc .; acrylic acid , Methacrylic acid, unsaturated carboxylic acids such as maleic acid and polymers thereof; further, alkyl acrylate, alkyl methacrylate, acrylate and methacrylate having an alkoxy group,
Copolymers of the above unsaturated carboxylic acids and polymerizable monomers such as polyalkylene glycol monoacrylates and methacrylate vinyl esters, alkali metals thereof, ammonium, partially or completely neutralized products with amines, and the like. They are used alone or in combination of two or more. The amount of the surface treatment agent is not particularly limited, but is usually 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight, per 100 parts by weight of the inorganic particles.
Parts by weight.

The bellows-like particles may be used alone,
It is also possible to use together with other inorganic particles for the same purpose.
At that time, the content of the bellows-shaped particles with respect to the whole particles is preferably 2% by weight or more, more preferably 10% by weight or more, and further preferably 30% by weight or more. If the addition ratio of the bellows-like particles is small, the effect intended by the present invention may be impaired by other particles. Particularly, as the inorganic particles when used in combination, precipitated calcium carbonate is preferred, and among them, hexahedral particles are easily used together. This is because the calcium carbonate produced by sedimentation is easy to control the particle size of the inorganic particles, and the content of the particle size is also easy to adjust, so that the characteristics of the bellows-like particles are not easily damaged. In this case, the precipitated calcium carbonate particles are more preferably hexahedral from the viewpoint of the shape effect.
Therefore, it is preferable to prepare the bellows-like particles using precipitated calcium carbonate in view of the hardness, the ease of adjusting the particle size, and the ease of operation of the particle diameter.

The method for preparing the bellows-like particles in the present invention is not particularly limited. For example, in the case of precipitated calcium carbonate, the above-mentioned carbon dioxide method may be used, or a method called solution method, which will be described below. But no problem. As a method for preparing calcium carbonate prepared by a solution method precipitation method, a carbonate solution (eg, sodium carbonate) and a calcium salt solution (eg, calcium chloride) are used as a reaction buffer, for example, in the presence of a sodium hydroxide solution in the presence of temperature, concentration and other reaction conditions. It is easily prepared by mixing under controlled conditions.

The synthetic resin in the present invention is not particularly limited. For example, the acrylic resin is a polymer containing methyl methacrylate as a main component, and may be a homopolymer of methyl methacrylate or copolymerizable with methyl methacrylate. Copolymers with other unsaturated monomers may be used. Examples of other copolymerizable unsaturated monomers include acrylates, methacrylates, and styrene. Further, a polyfunctional compound such as glycol dimethacrylate can be copolymerized. The degree of polymerization of these acrylic resins is from 500 to 30,000, preferably from 2,000 to 20,000 in terms of viscosity average degree of polymerization.

Examples of the polyolefin include polyethylene, polypropylene, poly-4-methylpentene-1, ethylene-propylene random or block copolymer, ethylene-propylene-butene copolymer, ethylene-propylene-hexene copolymer and the like. Can be mentioned. Among them, polypropylene or a copolymer of propylene with a majority of propylene and another α-olefin is preferable, and a propylene polymer having an ethylene content of 0 to 6% by weight is particularly preferable. Further, these polyolefins are crystalline and have an isotactic index of usually 40 or more, especially 60 or more, particularly 90 or more.
Further, it is used as long as it can be molded, but usually has a melt flow rate of 0.01 to 100 g / 10 min, especially 0.1 to 50 g / 10 min, particularly 0.5 to 10 g / min.
10 minutes is preferred.

The polyester is not particularly limited as long as it is a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. Examples of the aromatic dicarboxylic acid include terephthalic acid, naphthalenedicarboxylic acid, isophthalic acid, diphenylethanedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfondicarboxylic acid, diphenylketonedicarboxylic acid, and anthracenedicarboxylic acid. it can. Examples of the aliphatic glycol include alicyclic groups such as polymethylene glycol having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, and decamethylene glycol, and cyclohexanedimethanol. Diols and the like can be mentioned. As the polyester containing these as main components, for example, those containing alkylene terephthalate and / or alkylene naphthalate as a main component are preferably used.

The accordion-like particles are, as described above, a light diffusing agent,
Since it is particularly effective as an anti-blocking agent for films and the like, it is particularly effective when used as a resin suitable for producing sheets, films or synthetic fibers having a thickness of 5 mm or less. The synthetic resin composition of the present invention may contain other commonly used additives such as pigments, dyes, ultraviolet absorbers, various stabilizers, antioxidants, light-blocking agents (eg, carbon black, titanium oxide, etc.), processing aids, and the like. Needless to say, one or more kinds of agents, antistatic agents and the like can be used according to a standard method as required. Further, after these bellows-like particles are effectively used as an anti-blocking agent for a film or a fiber, it is also possible to dissolve and remove the particles themselves as necessary to form fine holes in the film or the fiber. Also in this case, as a component of the bellows-like particles, calcium carbonate which can be easily dissolved and removed with an acid is advantageous.

[0028]

EXAMPLES The present invention will be described below in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by these. In addition, about the evaluation, it performed by the following operation with two types of compounding.

[Acrylic Resin Sheet] An additive composed of inorganic particles was added to 100 parts by weight of a bead having a molecular weight of 140,000, which is a methyl methacrylate copolymer containing 7.5% by weight of ethyl acrylate. After adding the parts by weight described in Table 4 and mixing with a Henschel mixer, the molten resin was extruded from a T-die at a resin temperature of 265 ° C. using a 40 mm 1 screw extruder, and a 23 cm thick 2 mm sheet was passed through three polishing rolls. Created.

The quality of the sheet thus obtained was evaluated by the following method. Total light transmittance Integrating sphere HT based on ASTM D-1003-61
It was measured with an R meter. Concealment and light diffusivity The transmitted light intensity (I ₀ ) at a transmission angle of 0 ° by normal incident light, the transmitted light intensity (I ₅ ) at a transmission angle of 5 ° by normal incident light, and the normal incident light intensity (I ₇₀ ) Made by Murakami Color Research Laboratory
Measured using an automatic goniophotometer GP-1R, and I ₅ / I ₀
Was defined as concealing property, and I ₇₀ / I ₀ was defined as light diffusing property.

"Polyethylene terephthalate film"
As shown in Table 4, an additive composed of inorganic particles was suspended in ethylene glycol in advance, and each of the ethylene glycol slurries was added prior to the polyesterification reaction to carry out a polyesterification reaction, containing 0.1% by weight of the additive particles. Intrinsic viscosity (orthochlorophenol, 35 ° C) 0.62dl /
g of polyethylene terephthalate was prepared. After drying the polyethylene terephthalate at 160 ° C.,
, And rapidly solidified on a casting drum kept at 40 ° C. to obtain an unstretched film. Subsequently, the unstretched film was preheated to 70 ° C. with a heating roller, and then stretched 3.6 times in the longitudinal direction while heating with an infrared heater. Subsequently, the film was stretched 4.0 times in the transverse direction at a temperature of 90 ° C., and then heat-treated at 200 ° C. to obtain a biaxially oriented film having a thickness of 15 μm. The quality of the film thus obtained was evaluated by the following method.

The film surface roughness (Ra) is a value defined by JIS-B0601 as the center line average roughness (Ra). In the present invention, a stylus type surface roughness meter (SURFCORDER SF- 30C). The measurement conditions and the like are as follows. (A) Probe tip radius: 2 μm (b) Measurement pressure: 30 mg (c) Cut-off: 0.25 mm (d) Measurement length: 0.5 mm (e) Repeat measurement for the same sample 5 times Except for one, it represents the average value of the remaining four data.

The coefficient of friction (μk) of the film is measured as follows using the apparatus shown in FIG.
In the figure, 1 is an unwinding reel, 2 is a tension controller, 3, 5, 6, 8, 9 and 11 are free rollers, 4
Is a tension detector (entrance), 7 is stainless steel SUS
A fixed rod 304 (outer diameter 5 mm), 10 is a tension detector (outlet), 12 is a guide roller, and 13 is a take-up reel. In an environment of temperature 20 ° C and humidity 60%,
A film cut to a width of 1/2 inch is moved at a speed of 200 cm / min by contacting a fixing rod (surface roughness: 0.3 μm) of 7 with an angle θ = (152/180) π radian (152 °). (Friction). The outlet tension (T2: g) when the tension controller is prepared so that the inlet tension T1 becomes 35 g is detected by the outlet tension detector after the film has traveled 90 m, and the running wear coefficient μk is calculated by the following equation. μk = (2.303 / θ) log (T2 / T1) = 0.86 log (T2 / 35)

Abrasion Evaluation—I A half-width film surface was brought into contact with a stainless steel fixing pin (surface roughness 0.58) having a diameter of 5 mm at an angle of 150 °,
Reciprocate and rub about 15 cm at a speed of 2 m / min.
(At this time, the entry side tension T1 is set to 60 g). This operation is repeated, and the degree of scratches generated on the friction surface after the measurement of 40 reciprocations is visually judged in four stages based on the following criteria. ◎: Almost no scratching was observed. : Scratch is slightly observed. Δ: Scratch is considerably observed. ×: Many scratches are observed on the entire surface.

Abrasion Evaluation—II The abrasion of the running surface of the film is evaluated using a five-stage mini super calender. The calender is a five-stage calender of nylon rolls and steel rolls. The processing temperature is 80 ° C, the linear pressure applied to the film is 200 kg / cm, and the film speed is 50 m / min. When the running film has traveled a total length of 4000 m, the sharpness of the film is visually evaluated in four steps according to the following criteria due to dirt adhering to the top roller of the calendar. ◎: There is no dirt on the nylon roll. ○: Almost no dirt on the nylon roll. Δ: The nylon roll is slightly stained. ×: The nylon roll is considerably soiled. XX: The nylon roll is very dirty.

Number of Coarse Protrusions on Film Surface After aluminum was thinly vapor-deposited on the film surface, the number of coarse protrusions (the number per 1 mm ^{2 of the} measurement area) of a quadruple ring or more was counted using a ^two- beam interference microscope. It is represented by the following first to fifth grades depending on the degree of First grade: 16 or more Second grade: 12 to 15 Third grade: 8 to 11 Fourth grade: 4 to 7 Fifth grade: 0 to 3

Example 1 Preparation of Inorganic Particle-A 1.0 mol / liter sodium carbonate solution (X solution), 1.0 mol / liter calcium chloride solution (Y solution), and 0.03 mol / liter concentration Of sodium hydroxide solution (Z solution) was prepared for each 100 liters. The X solution and the Z solution were mixed, the solution temperature was adjusted to 17 ° C., and the Y solution similarly adjusted to 17 ° C. was added dropwise to the mixed solution under stirring conditions. Since this product had a pH of 12, dehydration and washing with tap water were repeated using a centrifugal dehydrator and concentrated when the pH reached 9 to obtain inorganic particles composed of precipitated calcium carbonate. As a result of observing the obtained calcium carbonate with an electron microscope, it was found that the sample contained 50% by weight of bellows-like particles shown in Table 1, and the others were hexahedral particles having a side length of 0.8 μm.

Example 2 Preparation of Inorganic Particle-B The same procedure as in Example 1 was performed except that the X solution concentration and the Y solution concentration were changed to 1.8 mol / liter and the Z solution was changed to 0.06 mol / liter. The method obtained inorganic particles composed of precipitated calcium carbonate. Observation of the obtained calcium carbonate with an electron microscope revealed that the powder contained 70% by weight of bellows-like particles shown in Table 1, and others were hexahedral particles having a side length of 0.2 μm. An electron micrograph (40) showing the shape of the obtained particles
FIG. 8).

Example 3 Preparation of Inorganic Particle-C The same procedure as in Example 1 was carried out except that the X solution concentration and the Y solution concentration were each changed to 1.4 mol / liter and the Z solution was changed to 0.045 mol / liter. The method obtained inorganic particles composed of precipitated calcium carbonate. The obtained calcium carbonate was observed with an electron microscope.
%, And the others were hexahedral particles having a side length of 0.4 μm.

Example 4 Preparation of Inorganic Particle-D The same procedure as in Example 1 was performed except that the X solution concentration and the Y solution concentration were changed to 0.6 mol / liter and the Z solution was changed to 0.025 mol / liter. The method obtained inorganic particles composed of precipitated calcium carbonate. The obtained calcium carbonate was observed with an electron microscope.
% By weight, and others were hexahedral particles having a side length of 2.4 μm.

Example 5 Preparation of Inorganic Particle-E Except that the X solution concentration was changed to 1.0 mol / liter, the Y solution concentration was changed to 0.8 mol / liter, and the Z solution was changed to 0.025 mol / liter. Thus, inorganic particles composed of precipitated calcium carbonate were obtained in the same manner as in Example 1. As a result of observing the obtained calcium carbonate with an electron microscope, it was found that the powder contained 20% by weight of bellows-like particles shown in Table 1, and the others were hexahedral particles having a side length of 1.4 μm.

Example 6 Preparation of Inorganic Particle-F The same as Example 1 except that the X solution concentration and the Y solution concentration were changed to 1.6 mol / liter and the Z solution was changed to 0.055 mol / liter. The method obtained inorganic particles composed of precipitated calcium carbonate. As a result of observing the obtained calcium carbonate with an electron microscope, the bellows-like particles shown in Table 1 were 90
%, And the others were hexahedral particles having a side length of 0.25 μm.

[0043]

[Table 1]

Comparative Example 1 Inorganic Particle-G Commercially available calcium carbonate produced by hexahedral sedimentation without bellows-like particles, average particle diameter 9 μm. Table 2 shows the characteristic values of the particles when one direction of the hexahedron is regarded as the laminating direction of the bellows-like particles.

Comparative Example 2: Inorganic Particles-H Commercially available hexahedral sedimented calcium carbonate free of bellows-like particles, average particle diameter 1 μm. Table 2 shows the characteristic values of the particles when one direction of the hexahedron is regarded as the laminating direction of the bellows-like particles.

Comparative Example 3: Inorganic Particle-I Commercially available surface treatment (treatment agent: stearic acid) heavy calcium carbonate, average particle diameter 1 μm. Table 2 shows other special values.

Comparative Example 4: Inorganic particles-J Commercially available spherical silica, average particle diameter 0.3 μm. Table 2 shows other special values.

Comparative Example 5 Preparation of Inorganic Particle-K Except that the X solution concentration was changed to 0.4 mol / liter, the Y solution concentration was changed to 1.0 mol / liter, and the Z solution was changed to 0.02 mol / liter. In the same manner as in Example 1, inorganic particles composed of precipitated calcium carbonate were obtained. As a result of observing the obtained calcium carbonate with an electron microscope, a large number of bellows-like particles and hexahedral calcium carbonate having the special values shown in Table 2 are aggregated, and primary particles having various particle sizes are present, The proportion containing the bellows-like particles was 30% by weight.

Comparative Example 6 Preparation of Inorganic Particle-L Milk of lime prepared by adding water to quicklime was prepared to have a specific gravity of 1.07.
0, the temperature was adjusted to 10 ° C, and the concentration of carbon dioxide in the milk of lime was 2
5% by weight of furnace gas is supplied at a conduction speed of 20 m ³ / min,
A carbonation reaction was performed, and the carbonation reaction was terminated at pH 6.5. The temperature of the aqueous calcium carbonate suspension after the completion of the carbonation reaction was adjusted to 70 ° C., and the mixture was stirred for 120 hours. The calcium carbonate prepared in this manner is a calcite-type calcium carbonate, and is obtained by scanning electron micrograph.
The secondary particle size was 0.5 μm. This aqueous suspension of calcium carbonate is dehydrated according to a conventional method, and the obtained dehydrated cake is prepared by adding sodium polyacrylate to the calcium carbonate solid content in an amount of 1.
By adding 5% by weight and stirring vigorously, an aqueous slurry of calcium carbonate having a solid content of 45% by weight was obtained. The water slurry was passed through a wet pulverizer (Dynomill Pilot type, manufactured by WAB, media filling ratio: 80%, media: 0.6 to 0.9 mm, rotation speed: 1500 rpm) repeatedly and six times at a flow rate of 60 cc / min. Pulverization was performed to disperse the aggregate. Table 2 shows the special values of this.

[0050]

[Table 2]

Examples 7 to 9 Each of the above concentrated slurries of the inorganic particles A, D and E was dried,
After being crushed to obtain untreated powder, the untreated powder was subjected to a surface treatment with 1.5 parts by weight of stearic acid using a super mixer to obtain these surface-treated powders. An acrylic resin-based light diffusion sheet was prepared by blending each of the surface-treated powders by the method described above, and the physical properties as a diffusion plate were evaluated. Table 3 shows the compounding amount, the ratio of the bellows-like particles, and the evaluation results.

Examples 10 to 11 Each of the above concentrated slurries of the inorganic particles B and C was dried and crushed to obtain untreated powder, and then 1.5 parts by weight with respect to the untreated powder using a super mixer. These surface-treated powders were obtained by subjecting stearic acid to surface treatment. An acrylic resin-based light diffusion sheet was prepared by using each of the surface-treated powders and commercially available precipitated calcium carbonate-made hexahedral particles (inorganic particles-G) in a ratio of 5: 5, and blending them by the method described above. It was prepared and its physical properties as a diffusion plate were evaluated. Table 3 shows the compounding amount, the ratio of the bellows-like particles, and the evaluation results.

Comparative Examples 7 to 10 Powders obtained by subjecting the inorganic particles G, H, I and inorganic particles K to surface treatment in the same manner as in Example 7 were used and blended in the same manner as in Example 1. An acrylic resin-based light diffusion sheet was prepared and the physical properties as a diffusion plate were evaluated. Table 3 shows the compounding amounts and evaluation results.

As is clear from Table 3, the light diffusing plate made of the synthetic resin composition containing the bellows-like inorganic particles of the present invention was balanced in all aspects of total light transmittance, concealing property and light diffusing property. Has characteristics.

[0055]

[Table 3]

Examples 12 to 16 Using a concentrated slurry of the above-mentioned inorganic particles A, B, C, E and F, a surface treating agent (acrylic acid and butyl methacrylate) equivalent to 1.5% by weight based on the inorganic particles was used. Is a copolymer having a weight ratio of 70:30, in which 20% of the total carboxyl groups of the acrylic acid portion are ammonium salts), and the resulting mixture is subjected to surface treatment under stirring conditions, and then using a spray drier. Spray drying was performed, and a polyester film in which each was blended was prepared by the method described above, and the physical properties were evaluated. Table 4 shows the compounding amount, the ratio of bellows-like particles, and the evaluation results.
It describes in.

Examples 17-18 Hexahedral particles (inorganic particles-H) composed of powder obtained by subjecting the above inorganic particles B and F to surface treatment in the same manner as in Example 12 and commercially available precipitated calcium carbonate were mixed in a ratio of 3: 7. Polyester films were used in combination at the above ratios and blended with each other by the above-described method, and the physical properties thereof were evaluated. Table 4 shows the compounding amount, the ratio of the bellows-like particles, and the evaluation results.

Comparative Examples 11 to 14 The above-mentioned inorganic particles H and J and inorganic particles K and L were surface-treated in the same manner as in Example 6 and powders were blended in the same manner as in Example 12. A polyester film was prepared and its physical properties were evaluated. Table 4 shows the compounding amount, the ratio of the bellows-like particles, and the evaluation results.

As is clear from Table 4, the film made of the synthetic resin composition containing the bellows-like inorganic particles of the present invention has properties required as a film in all aspects of surface roughness, coefficient of friction and abrasion. And the number of coarse projections is small.

[0060]

[Table 4]

[0061]

EFFECT OF THE INVENTION By using the bellows-like inorganic particles of the present invention, in the case of a synthetic resin such as an acrylic resin or polyester, good light diffusion without lowering the total light transmittance when made into a sheet-like material. Give the effect,
Good blocking resistance and abrasion resistance can be imparted to films and fibers, and their usefulness is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing bellows-like inorganic particles of the present invention.

FIG. 2 is a schematic front view showing the bellows-like inorganic particles of the present invention.

FIG. 3 is a schematic side view showing the bellows-like inorganic particles of the present invention.

FIG. 4 is an explanatory diagram in the case where the tops (corners) of hexahedral particles are located near the film surface.

FIG. 5 is an explanatory diagram in a case where sides of hexahedral particles are located near a film surface.

FIG. 6 is an explanatory diagram in the case where the bellows-like inorganic particles of the present invention are located near the film surface.

FIG. 7 is an electron micrograph (× 40000) showing the shape of the bellows-like inorganic particles (B) obtained in Example 2.

FIG. 8 is a schematic view showing an apparatus for measuring a coefficient of friction of a film.

Claims (9)

[Claims] 1. Bellows-like inorganic particles characterized in that the cross section perpendicular to the laminating direction is substantially a quadrilateral and satisfies all of the following requirements (1) to (5). (1) 0.6 ≦ b / a ≦ 1.5 (2) 0.8 ≦ c / a ≦ 5.0 (3) n ≧ 3 (4) S ≦ 1 (5) 0 ≦ (DP1-DP3) / DP2 ≦ 1 where, a: average (μm) of arbitrarily determined length of one side of a quadrilateral of a cross section perpendicular to the laminating direction b: X of the same cross section with the side direction of a as the X axis Average length of particles in the Y-axis direction perpendicular to the axis (μm) c: Average of particle length in the Z-axis direction in the lamination direction perpendicular to the X-axis as the Z-axis (μm) n: Stack of layers Average number of layers DP1: Light transmission type particle size distribution analyzer (SA- manufactured by Shimadzu Corporation)
In the particle size distribution using CP3), the particle size (μm) at 25% of the cumulative weight calculated from the larger particle size side DP2: Light transmission type particle size distribution analyzer (Shimadzu SA-
In the particle size distribution using CP3), the particle size (μm) at 50% of the cumulative weight calculated from the larger particle size side DP3: Light transmission type particle size distribution analyzer (Shimadzu SA-
In the particle size distribution using CP3), the particle size (μm) at a cumulative weight of 75% calculated from the larger particle size side S: relative standard deviation ai: The average of the lengths (μ) of arbitrarily determined sides of a quadrilateral having a cross section perpendicular to the laminating direction of the individual bellows-like particles.
m) bi: average length (μm) of particles in the Y-axis direction perpendicular to the X-axis of the same cross-section, with the ai side direction of each bellow-like particle as the X-axis; ci: X-axis of each bellow-like particle The stacking direction perpendicular to
Average length of particles in the Z-axis direction as an axis (μm) DC1: Length of one side length of a cube (μm) showing the same value as the average value of the volume of individual bellows-like particles as a square prism 2. The bellows-like inorganic particles according to claim 1, further comprising the following requirements. (6) 0.6 ≦ b1 / a ≦ 1.5 (7) 0.6 ≦ b2 / a ≦ 1.5, where b1 is the length of the side in contact with one vertex of the side in the a direction of the quadrilateral. Average (μm) b2: average length (μm) of the side in contact with another vertex of the side in the a direction of the quadrilateral 3. The bellows-like inorganic particles according to claim 1, further comprising the following requirements. (8) 0.05 μm ≦ DP2 ≦ 0.5 μm 4. The method according to claim 1, comprising calcium carbonate produced by sedimentation.
4. The bellows-like inorganic particles according to any one of items 1 to 3. 5. A synthetic resin composition comprising the bellows-like inorganic particles according to claim 1. Description: 6. The synthetic resin composition according to claim 5, wherein the bellows-like inorganic particles are a mixture containing other inorganic particles. 7. The synthetic resin composition according to claim 6, wherein the content of the bellows-like particles is 2% by weight or more of the whole particles. 8. The synthetic resin composition according to claim 6, wherein the other inorganic particles are hexahedral particles made of precipitated calcium carbonate. 9. The synthetic resin composition according to claim 5, wherein the synthetic resin composition is a sheet, film or synthetic fiber having a thickness of 5 mm or less.