JP5100972B2 - Light reflecting porous film filler and light reflecting porous film containing the filler - Google Patents

Description

The present invention includes a filler for a light-reflecting porous film composed of surface-treated inorganic particles that are easy to mix with a resin, have good dispersibility in the resin, and have few impurities and coarse particles, and the filler. It relates to the porous film which becomes.
More specifically, for example, the workability at the time of premixing with a resin and other additives is good, the molecular chain of the resin at the time of melt-kneading is hardly broken (molecular deterioration), and has good dischargeability. In addition, re-aggregation between particles, other additives, and resin is unlikely to occur, and since there are almost no impurities or coarse particles, for example, a porous film that does not easily deteriorate in strength can be obtained, and the particle size can be manipulated. And it is possible to disperse the film in the film very uniformly, so that a porous film in which the pore size distribution width is uniformly controlled can be obtained. The present invention relates to a filler and a light reflecting porous film formed by blending the filler.

Porous films made of synthetic resins are used in a wide variety of applications such as synthetic paper, sanitary materials, medical materials, building materials, agricultural air permeable sheets, separators for various batteries, and light reflectors for liquid crystal displays. Therefore, further improvements and developments are required for any application.
For example, a transmissive liquid crystal display is used as a monitor for a personal computer or a display device for a thin TV, and such a liquid crystal display is usually provided with a planar illumination device called a backlight on the back of the liquid crystal element. Has been.

The backlight has a function of converting a linear light source such as a cold cathode discharge tube into a planar light source. As a typical structure, the backlight has a light source installed just under the back of the liquid crystal element, and a line from the side. There is a method (side light type) in which a planar light source is passed through a translucent light guide such as an acrylic plate to convert light into a planar shape and obtain a planar light source.
In response to consumer demands for lighter and thinner displays in recent years, a sidelight type that can structurally make the backlight unit thinner is preferred as a display device, and is used as a liquid crystal display device such as a portable personal computer. Is heavily used.

The typical structure of a sidelight type backlight unit is a light guide plate made of an acrylic plate, a light reflector made of foamed polyester or polyolefin film, a metal vapor-deposited film, etc., or a light diffusion installed on the opposite surface of the light reflector. It consists of a cold cathode discharge tube installed on the side of the plate and the light guide plate.
Reflective paint is halftone printed on the surface of the light guide plate facing the light reflector side, and the linear light introduced from the side surface of the light guide plate emits light at the dot print portion and is reflected by the light reflector. A uniform surface is formed by a diffusion plate together with light.

The function required of the light reflector in the backlight unit is to efficiently use light from the built-in light source and display that meets the needs of consumers.
In other words, it is required to reflect light that passes through the light guide plate from the light guide plate to the reflection plate side without any waste and with uniform brightness, and liquid crystal color display has become commonplace. A color liquid crystal cell which is a main device is required to have a sufficient luminance for a light source because of its low light transmittance.
In addition, since the specular reflection that is generally glaring is disliked by consumers, it is necessary to realize a relatively uniform luminance in the direction of the exit surface by scattering reflection and to let the light from the display feel naturally.

For the physical properties required for the above light reflecting plate, for example, a white polyester film described in Patent Document 1 has been used conventionally (see, for example, Patent Document 1), and the change in color tone of the white polyester film is also known. For the purpose of improvement, porous polyolefin films have been proposed (see, for example, Patent Documents 2 and 3).
Japanese Patent Laid-Open No. 04-239540 JP 2002-31704 A JP 2004-157409 A

  However, due to the significant progress of IT technology in recent years, not only the display device itself is becoming larger and lighter in the surface direction, but also thinner in the thickness direction, as well as the precision of the display pixels is required. The luminance of light emitted from a light source is required to be higher and stable over time.

  However, the white polyester film of Patent Document 1 causes a change in color tone from a liquid crystal display or a decrease over time due to deterioration of the resin near the light source due to heat emitted from the light source or light having a wavelength near ultraviolet light. There was a thing. In particular, due to the demand for higher brightness, the light source itself is powerful and the distance from the light source is shortened, so that the deterioration of the resin becomes remarkable and the stability over time is required.

In Patent Documents 2 and 3, a polyolefin resin, which is said to be less deteriorated with time than a polyester resin, is used, and particles such as heavy calcium carbonate and barium sulfate are used as particles that generate fine pores in the resin. By using the inorganic particles, it is possible to obtain a film in which the luminance is less decreased and is more stable over time, the resin itself is flexible, and the light guide plate is not easily damaged.
However, the demand for higher luminance for the current liquid crystal display device is not satisfied by the above-described method, and further improvement has been desired.

  The present invention has been made in view of the above circumstances, and is a surface-treated inorganic material that can be easily mixed with a resin to be a light-reflecting porous film substrate, has good dispersibility in the resin, and has few impurities and coarse particles. A light-reflecting porous film comprising a filler for light-reflecting porous film composed of particles and the filler is provided, and, for example, workability at the time of premixing with a resin or other additive is good, There is almost no molecular chain breakage (molecular degradation) during melt-kneading, and it has good ejection properties, is less likely to cause re-aggregation between particles and other additives, and can be manipulated in particle size. And it is possible to disperse the film in the film very uniformly, so that a porous film in which the distribution width of the void diameter is uniformly controlled can be obtained. Light-reflecting porous material comprising a filler and the filler An object of the present invention is to provide a film.

As a result of intensive studies for solving the above problems, the present inventors have used, as a surface treatment agent, a surfactant (A) and a compound (B) having a chelating ability with respect to an alkaline earth metal as inorganic particles. In combination with satisfying specific particle size characteristics, it is possible to obtain surface-treated inorganic particles having extremely excellent dispersibility with respect to the resin, and easy blending of the obtained surface-treated inorganic particles into the resin, In addition, it can be dispersed well without causing re-aggregation and the like. Furthermore, when the resin composition for a porous film containing the surface-treated inorganic particles is used for a film stretched uniaxially or biaxially, for example, a good void is generated. However, the present invention has been completed by finding that the above problems are solved, such as being useful as a film for a light reflector of a backlight device such as a liquid crystal display.

That is, claim 1 of the present invention is that inorganic particles containing an alkaline earth metal are saturated fatty acid, alicyclic carboxylic acid, aromatic sulfonic acid, salt thereof, ester thereof, alcohol surfactant, sorbitan Fatty acid esters, amide surfactants, amine surfactants, polyoxyalkylene alkyl ethers, polyoxyethylene nonyl phenyl ether, alpha olefin sodium sulfonate, long chain alkyl amino acids, amine oxides, alkyl amines, quaternary Surface treatment with at least one surfactant (A) selected from ammonium salts and at least one compound selected from condensed phosphoric acid and salts thereof (B) having a chelating ability for alkaline earth metals In the slurry of the inorganic particles , the surface treatment of the compound (B) A filler for light-reflecting porous films, which is formed by mixing the surfactant (A) in the presence and satisfies the following particle size characteristics (1) to (4).
(1) 0.3 ≦ D ₅₀ ≦ 1.5 [μm]
(2) 0.02 ≦ Dx ≦ 0.6 [μm]
(3) Da ≦ 20 [μm]
(4) 3 ≦ Sw ≦ 20 [m ² / g]
However, D ₅₀ : Cumulative average particle diameter on a sieve [μm] measured with Leeds & Northrup Microtrac FRA (Microtrac)
Dx: Observation with a scanning electron microscope at a magnification of 20,000 times, arbitrarily select 100 particles, and remove the average particle size from the maximum and minimum 20 particles each [μm]
Da: Maximum particle size [μm] measured by Microtrac FRA (Microtrac) manufactured by Leeds & Northrup
Sw: BET specific surface area by nitrogen adsorption method [m ² / g]

  A second aspect of the present invention is the light reflecting porous film filler according to the first aspect, wherein the inorganic particles are calcium carbonate or barium sulfate.

  A third aspect of the present invention is the light reflecting porous film filler according to the first or second aspect, wherein the surfactant (A) is a fatty acid salt.

  According to a fourth aspect of the present invention, the surfactant (A) contains 50 to 98% by weight of a straight chain fatty acid salt having 16 or more carbon atoms and 2 to 50% by weight of a straight chain fatty acid salt having 10 to 14 carbon atoms. The filler for light-reflecting porous films according to any one of claims 1 to 3, wherein:

  According to a fifth aspect of the present invention, the condensed phosphoric acid of the compound (B) having a chelating ability with respect to an alkaline earth metal is a cyclic condensed phosphoric acid or a metaphosphoric acid. The filler for light reflecting porous films according to claim 1.

  Claim 6 of the present invention is that the surfactant (A) is 0.1 to 15% by weight and the compound (B) having chelating ability to the alkaline earth metal is 0.05 to 5% by weight with respect to the inorganic particles. It is a filler for light reflection porous films of any one of Claims 1-5 characterized by these.

A seventh aspect of the present invention is a light reflecting porous film comprising a resin and the filler for a light reflecting porous film according to any one of the first to sixth aspects.

Claim 8 of the present invention, the amount of light reflecting filler for porous films is a light reflective porous film according to claim 7, wherein 60 to 150 parts by weight per 100 parts by weight of the resin.

The ninth aspect of the present invention is the light reflecting porous film according to the seventh or eighth aspect, wherein the resin is an olefin resin.

A tenth aspect of the present invention is the light reflecting porous film according to any one of the seventh to ninth aspects, wherein the light reflecting porous film is used for a light reflector of a liquid crystal display device or a lighting device.

The eleventh aspect of the present invention is the light reflecting porous film according to the tenth aspect, which is used for the light reflecting layer of the light reflector.

The filler for light-reflecting porous film comprising the surface-treated inorganic particles of the present invention can be easily mixed with a resin and has good dispersibility in the resin. For example, a light reflector for a backlight device of a liquid crystal display A porous film useful as a light reflection layer can be provided.
Further, the filler for light reflecting porous film of the present invention can be mixed with the resin quickly, and, for example, has little adhesion to the inner wall surface of the mixer or the blade for stirring / mixing, so that the fluctuation of the blending is small. Stabilize. In addition, it is characterized in that the generation of denatured resin and agglomerates that induce adhesion inside the mixer is reduced, and the workability of mixing and the occurrence of clogging of the strainer in the kneading extruder in the subsequent process are reduced.

As the surfactant (A) used in the present invention, saturated fatty acids, alicyclic carboxylic acids, aromatic sulfonic acids, their these salts, or their esters, alcohol surfactant, sorbitan fatty acid esters, Amide surfactants, amine surfactants, polyoxyalkylene alkyl ethers, polyoxyethylene nonyl phenyl ether, alpha olefin sodium sulfonate, long chain alkyl amino acids, amine oxides, alkyl amines, quaternary ammonium salts, etc. These are exemplified, and these may be used alone or in combination of two or more as necessary.

Examples of saturated fatty acids include capric acid, lauric acid, myristic acid, palmitic acid, and stearic acid, and examples of alicyclic carboxylic acids include cyclopentane ring and naphthenic acid having a carboxyl group at the end of the cyclohexane ring. Examples of the aromatic sulfonic acid include linear alkylbenzene sulfonic acid, branched alkylbenzene sulfonic acid, dodecylbenzene sulfonic acid, and the like, and examples of the resin acid include abietic acid, pimaric acid, neoabietic acid, and the like.

Examples of alcohol-based surfactants include sodium alkyl sulfates and sodium alkyl ether sulfates. Examples of sorbitan fatty acid esters include sorbitan monolaurate and polyoxyethylene sorbitan monostearate. Examples of amine surfactants include fatty acid alkanolamides and alkylamine oxides. Examples of polyoxyalkylene alkyl ethers include polyoxyethylene alkyl ethers and polyoxyethylene lauryl ethers. Include lauryl betaine, stearyl betaine, and the like .

  Examples of amine oxides include polyoxyethylene fatty acid amides and alkylamine oxides. Examples of alkylamines include stearylamine acetate. Examples of quaternary ammonium salts include stearyltrimethylammonium chloride and quaternary ammonium sulfate. Etc.

Examples of the salts of the various acids include alkali metal salts such as potassium and sodium. Specifically, potassium laurate, potassium myristate, potassium palmitate, sodium palmitate, potassium stearate, sodium stearate. saturated fatty acid salts and the like, Na Putian lead, alicyclic carboxylates and cyclohexyl butyrate lead, sodium linear alkyl benzene sulfonate, and aromatic sulfonic acid salts such as sodium dodecylbenzenesulfonate.
Examples of the esters of the various acids include ethyl caproate, vinyl caproate, diisopropyl adipate, ethyl caprylate, allyl caprate, ethyl caprate, vinyl caprate, diethyl sebacate, diisopropyl sebacate, isooctanoic acid Cetyl, octyldodecyl dimethyloctanoate, methyl laurate, butyl laurate, lauryl laurate, methyl myristate, isopropyl myristate, cetyl myristate, myristyl myristate, isocetyl myristate, octyldodecyl myristate, isotridecyl myristate, palmitic Methyl acetate, isopropyl palmitate, octyl palmitate, cetyl palmitate, isostearyl palmitate, methyl stearate, butyl stearate, Stearate octyl, stearyl stearate, cholesteryl stearate, isocetyl isostearate, methyl behenate, saturated fatty acid ester such as behenyl behenate, other its long chain fatty acid higher alcohol esters, neopentyl polyol (long chain, medium-chain Fatty acid ester and partial ester compound, dipentaerythritol long chain fatty acid ester, complex medium chain fatty acid ester, 12-stearoyl stearate isocetyl, 12-stearoyl stearate isostearyl, 12-stearoyl stearate stearate, tallow fatty acid octyl ester Heat-resistant special fatty acid esters such as polyhydric alcohol fatty acid esters and fatty acid esters of alkyl glyceryl ethers, and aromatic esters represented by benzoic acid esters
The above surfactants may be used alone or in combination of two or more as required.

Among the surfactants described above, inorganic particles surface-treated with saturated fatty acid , alicyclic carboxylic acid, and aromatic sulfonic acid salts inhibit the insulation and heat resistance of the resin when blended in the resin. In particular, the dispersibility is good and preferable, and a salt of a fatty acid, particularly a mixture of an alkali metal salt is more preferable.

About the alkali metal salt of saturated fatty acid, the composition is 50 to 98% by weight of alkali metal salt of linear fatty acid having 16 or more carbon atoms such as palmitic acid, stearic acid, arachidic acid, behenic acid, capric acid, lauric acid, It is preferable that an alkali metal salt of a linear fatty acid having 10 to 14 carbon atoms such as myristic acid is present in a proportion of 2 to 50% by weight.
As for the alkali metal salt of a linear fatty acid having 16 or more carbon atoms, an alkali metal salt of a linear fatty acid having 18 or more carbon atoms such as stearic acid , particularly a potassium salt is preferable.
As for the alkali metal salt of a linear fatty acid having 10 to 14 carbon atoms, lauric acid having 12 carbon atoms is preferable from the viewpoint of dispersibility.

If the content of linear fatty acid having 16 or more carbon atoms in the composition of the alkali metal salt of linear fatty acid is less than 50% by weight, the reason is not clear compared with that of 50% by weight or more. The dispersibility of the resin slightly deteriorates, and if it exceeds 98% by weight, voids generated between the resin and the particles tend to be too small compared to 98% by weight or less.
In addition, if the content of C10-14 linear fatty acid in the fatty acid composition is less than 2% by weight, the effect of addition is not sufficient as compared with those having 2% by weight or more, and on the contrary, it exceeds 50% by weight. And less than 50% by weight or less, the affinity with the resin is impaired, and problems such as whitening and bleeding to the resin surface after molding tend to occur.

  When the above-mentioned alkali metal salt of a linear fatty acid is used as the surfactant (A), it is preferable to select and mix the fatty acids of the respective compositions, but the equivalent is within the range not impairing the efficacy of the present invention. You may use the commercially available soap etc. of a composition.

The amount of the surfactant (A) used varies depending on the specific surface area of the inorganic particles. In general, the larger the specific surface area, the larger the amount used.
However, although it is difficult to specify in general by various physical properties such as MI value of the resin used as the base material of the porous film and the active agent added at the time of compounding, it is usually 0.1% by weight with respect to the inorganic particles. More than 15% by weight.
If the amount used is less than 0.1% by weight, the surface of the inorganic particles cannot be sufficiently coated. As a result, a sufficient dispersion effect may not be obtained. On the other hand, if the amount used exceeds 15% by weight, bleeding to the porous film surface may occur. In some cases, a decrease in the strength of the porous film may be a problem.
The amount of the surfactant (A) used in the present invention is proportional to the specific surface area Swx of the inorganic particles to be surface-treated and is within a range of ± 20% centering on the amount represented by the following formula (1). If used, it has been found that the effect of the present invention is better.
[Use amount of surfactant (A) to inorganic particles (%)]
= 1/3 x [BET specific surface area Swx of inorganic particles before surface treatment] (1)

Examples of the compound (B) having a chelating ability for alkaline earth metals used in the present invention include ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, and the like. aminocarboxylic acid chelating agent typified by, hydroxyethylidene-diphosphite, phosphonic acid chelating agent or the like nitrilotris methylene phosphonic acid, Po Yi Lin acid, phosphoric acids and their salts exemplified typified by condensed phosphate Is done.
Examples of polyvalent carboxylic acid salts include sodium polyacrylate and ammonium polyacrylate, and examples of copolymer salts include ammonium salts of acrylic acid / maleic acid copolymers (polymerization ratio 100: 80, etc.), acrylic acid -Examples of phosphoric acid salts such as ammonium salts of methacrylic acid copolymers (polymerization ratio 100: 80, etc.) include sodium hexametaphosphate, sodium polyphosphate, sodium pyrophosphate, etc., either alone or as required Two or more types are used in combination.
In the present invention, in the compound (B) having a chelating ability with respect to these alkaline earth metals, polyphosphoric acid, condensed phosphoric acid, and polyphosphoric acid are used when uniform and uniform pores such as a light reflecting layer are required. A polyvalent carboxylic acid or a salt thereof is preferred, and among them, condensed condensed phosphoric acid is preferably cyclic condensed phosphoric acid or metaphosphoric acid.

The amount of the compound (B) having a chelating ability with respect to the alkaline earth metal varies depending on the specific surface area of the inorganic particles, the resin used, the compound conditions, etc. as described in the surfactant (A). Usually, it is preferably 0.05% by weight to 5% by weight with respect to the inorganic particles.
If the amount used is less than 0.05% by weight, the surface of the inorganic particles cannot be sufficiently coated, and as a result, a sufficient dispersion effect may not be obtained. Since improvement may not be recognized, it is not preferable.
Although there is no particular problem, the amount of the compound (B) having chelating ability with respect to the alkaline earth metal is proportional to the specific surface area Swx of the inorganic particles to be surface-treated and is represented by the following formula (2). It has been proved that it is better in achieving the effect of the present invention if it is used within a range of ± 20% centering on the amount of the above.
[Amount of compound (B) used for inorganic particles (%)]
= 1/9 x [BET specific surface area Swx of inorganic particles before surface treatment] (2)

Inorganic particles used in the present invention generally those water-insoluble, barium sulfate, calcium carbonate, basic magnesium carbonate, magnesium hydroxide, hydroxy hydrotalcite, hydroxyapatite, talc, main component as clay, subcomponent Alternatively, those containing an alkaline earth metal as an impurity are preferable, and calcium carbonate, basic magnesium carbonate, magnesium hydroxide, hydroxytalcite, and hydroxyapatite are particularly preferable.
Of these, barium sulfate and calcium carbonate are preferred because they are safe and inexpensive to obtain, and the particle size operation is relatively easy, and the impurities contained in the particles are small and easy to remove. However, the entire process is safe and the raw material itself is more preferable because it produces abundant high-quality limestone in Japan.

Calcium carbonate is generally obtained by reacting heavy calcium carbonate, which is obtained by mechanically grinding limestone, classifying the pulverized material and adjusting it to various grades, and quick lime obtained by baking limestone at a high temperature and water. The carbon dioxide compound method that synthesizes calcium carbonate by conducting carbon dioxide generated during limestone firing to the lime milk, the lime-sodium carbonate method that reacts sodium carbonate with lime milk, and the sodium carbonate reacts with calcium chloride It is roughly classified into two types of precipitated calcium carbonate (synthetic calcium carbonate) prepared by a chemical method such as calcium chloride-sodium carbonate method.
If the surface-treated calcium carbonate satisfying the conditions of the present invention, there is no difference in physical properties depending on the production method, but heavy calcium carbonate has various elements other than calcium carbonate as the raw material limestone because of its production method. For example, it is not preferable for a light reflector application requiring high-purity calcium carbonate that dislikes such impurities.
Further, calcium carbonate having a broad particle size distribution and having a fineness of a certain level or more is not preferable because it cannot be produced by the current pulverization / classification technology.

The lime-sodium carbonate method in which sodium carbonate is reacted with lime milk, the soda method in which sodium carbonate is reacted with calcium chloride, the resulting precipitated calcium carbonate has a sharp particle size and is easy to manipulate, and contains impurities Is extremely advantageous for use in the light reflecting layer of the present invention.
However, while the raw materials for precipitated calcium carbonate prepared by heavy calcium carbonate or carbon dioxide gas compound method are only limestone and coke / light oil used for firing, the method using sodium carbonate is usually the raw material In order to obtain sodium carbonate and calcium chloride, limestone and salt are industrially produced as starting material raw materials, and returning them to calcium carbonate is a cost-effective condition for obtaining raw materials However, it is not preferable in view of the load on the environment that has been attracting attention recently.
Further, since it is necessary to remove the counter ions, the point that a large amount of water is required for washing the particles after the reaction is not preferable in terms of cost and environmental load.

  Precipitated calcium carbonate obtained by reacting lime milk obtained by calcining limestone and dissolving the obtained quick lime in water and carbon dioxide gas obtained at the time of firing is fine and the particle size of the primary particles・ The shape is uniform and contains less impurities, and the particle size can be adjusted according to the reaction conditions and post-reaction processes, and is excellent in terms of economics and physical load on the physical properties of the resulting particles. It is suitable when used for a porous film for a light reflecting layer.

  In addition, it is preferable to perform a classification operation such as air classification on the calcium carbonate or surface-treated calcium carbonate powder obtained after drying and pulverization to remove aggregates generated by drying.

The resulting surface treatment method using a compound having a chelating ability (B) with respect to the above-described surfactant for calcium carbonate particles (A) and alkaline earth metals, interfacial active agents (A) and alkaline earth In the presence of the compound (B), the surfactant (A) is dissolved in a water slurry of calcium carbonate in which the compound (B) having a chelating ability for a metal is dissolved in water or hot water. after mixing to surface treatment, dehydration, a method generally called a wet process of drying, the degree and economic aspects of the process of the calcium carbonate particle surfaces, used good Mashiku.

The surface-treated inorganic particles in the present invention preferably have the following particle size characteristics (1) to (4).
(1) 0.3 ≦ D ₅₀ ≦ 1.5 [μm]
(2) 0.02 ≦ Dx ≦ 0.6 [μm]
(3) Da ≦ 20 [μm]
(4) 3 ≦ Sw ≦ 20 [m ² / g]
However, D ₅₀ : Cumulative average particle diameter on the sieve [μm] measured with Microtrac FRA manufactured by Leeds & Northrup
Dx: Observe at a magnification of 20,000 using a scanning electron microscope, select 100 particles arbitrarily, and remove the 20 particles from the largest and smallest particles, the remaining average particle size [μm]
Da: Maximum particle size [μm] measured by Microtrac FRA manufactured by Leeds & Northrup
Sw: BET specific surface area by nitrogen adsorption method [m ² / g]

The surface-treated inorganic particles in the present invention preferably have an average particle diameter D50 measured by Microtrac FRA manufactured by Leeds & Northrup in the range of 0.3 ≦ D ₅₀ ≦ 1.5 [μm], and 0.3 ≦ D ₅₀ ≦ More preferably, it is 1.0 [μm].
Although it is technically possible to make the average particle diameter D ₅₀ less than 0.3 μm, it is not preferable in terms of cost, and when D ₅₀ exceeds 1.5 μm, the agglomeration force of secondary particles composed of aggregates of primary particles However, it is not preferable because it is not suitable for a porous film for a light reflecting layer, for example, because it is present as a secondary particle even in a resin.

The particle diameter Dx measured from the electron microscope field of the surface-treated inorganic particles in the present invention is preferably 0.02 ≦ Dx ≦ 0.6 [μm], and more preferably 0.02 ≦ Dx ≦ 0.4 [μm].
When the particle diameter Dx exceeds 0.6 μm, it is not preferable because it creates large pores more than intended when blended into the light reflecting layer porous film. When the particle diameter is less than 0.02 μm, the cohesion between particles is strong, Since it does not disperse when blended with a resin, it exhibits the same behavior as coarse particles, and when blended in a porous film for a light reflecting layer, it creates a larger pore than intended, which is not preferable.

The surface-treated inorganic particles in the present invention preferably have a maximum particle size Da in the range of Da ≦ 20 [μm] as measured by the above Microtrack FRA, and Da ≦ 5 [μm]. More preferred.
When the maximum particle size Da exceeds 20 μm, for example, when blended in a porous film for a light reflecting layer, large pores more than intended are created, which is not preferable.

The medium used for the measurement with Microtrac FRA is appropriately selected depending on the surface treatment agent used for the surface treatment of the particles. Usually, water treated with a surface treatment agent exhibiting hydrophilicity is hydrophobic, Methanol or ethanol is preferably used for those surface-treated with a surface treatment agent exhibiting properties.
In the measurement of the present invention, an ultrasonic dispersion machine Ultra Sonic Generator US-300T manufactured by Nippon Seiki Seisakusho was used as a pre-dispersion in water or methanol / ethanol slurry used for the measurement, and irradiated at 300 μA for 60 seconds. It was measured later.

The surface-treated inorganic particles in the present invention preferably have a BET specific surface area Sw of 3 ≦ Sw ≦ 20 [m ² / g], and more preferably 5 ≦ Sw ≦ 20 [m ² / g ] .
If the BET specific surface area Sw exceeds 40 m ² / g, it is not preferable from the viewpoint of dispersibility. If the BET specific surface area Sw is less than 3 m ² / g, the primary particles are too large and larger than intended when incorporated in the porous film for a light reflecting layer. It is not suitable as the particles used in the backlight device, which is a use of the present invention, because it creates voids.

  The filler for a porous film comprising the surface-treated inorganic particles obtained as described above is blended with various resins, particularly olefin-based resins, for porous films for various uses, particularly porous films such as light reflecting layers. Used for manufacturing.

Although it does not restrict | limit especially as resin used for this invention, For example, polyester, a polycarbonate, polyethylene, a polypropylene, an ethylene propylene copolymer, a copolymer of ethylene or a propylene, and another monomer etc. are mentioned.
In particular, when used as a porous film for a light reflecting layer, the above-described decrease in luminance is small and more stable over time, the resin itself is flexible, and the light guide plate is not easily damaged. In view of this, polyolefin resins such as polyethylene and polypropylene are preferable, and polypropylene is more preferable.
The blending ratio of the filler for the light reflecting porous film and these resins is not particularly limited, and varies greatly depending on the type and use of the resin, desired physical properties and cost, and may be appropriately determined depending on them. It is 60-150 weight part with respect to a weight part, Preferably it is about 80-120 weight part.

  In addition, lubricants such as fatty acids, fatty acid amides, ethylene bis-stearic acid amides, sorbitan fatty acid esters, plasticizers and stabilizers, antioxidants are used for the purpose of improving film properties within the range that does not inhibit the efficacy of the surface-treated inorganic particles of the present invention. Additives etc. may be added, and additives generally used in resin compositions for films, such as lubricants, antioxidants, heat stabilizers, light stabilizers, UV absorbers, neutralizers, antifogging agents, anti-foaming agents, etc. You may mix | blend a blocking agent, an antistatic agent, a slip agent, a coloring agent, etc.

When the light-reflective porous film filler of the present invention and the above-mentioned various additives are blended into a resin, it is usually heated and kneaded with a single or twin screw extruder, a kneader, a Banbury mixer, etc., and a sheet is produced with a T die or the like. Later, the film is stretched uniaxially or biaxially to obtain a porous film product having fine pores.
Further, after kneading, a film is formed using a known molding machine such as T-die extrusion or inflation molding, and these are acid-treated to dissolve the filler for light-reflecting porous film of the present invention to have fine pores. It is good also as a light reflection porous film product.

The shape of the resin includes pellets and powders (granulated) adjusted to an arbitrary particle size. For dispersion of the particles, a powdery resin is used, and a known Henschel mixer, tumbler mixer, ribbon blender, etc. It is preferable to mix using a mixer called a mixer.
The filler for a light-reflecting porous film of the present invention shows good physical properties such as dispersibility in the resin compared to particles other than the present invention, even when used as a pellet-shaped resin. It is particularly good when mixed with resin. In addition, when mixed with a Henschel mixer, for example, in addition to the merit that mixing can be performed quickly, there is little adhesion to the inner wall of the mixer and the blades for mixing and mixing. It is characterized in that the generation of denatured resin and agglomerates that induce internal adhesion is reduced, the workability of mixing and the occurrence of clogging of the strainer in the kneading extruder in the subsequent process are reduced.

There are various models and setting conditions for the above-mentioned heating kneader, and the raw material charging method is appropriately determined in consideration of the influence on the MI value of the resin itself and the cost in addition to the dispersion of the particles in the resin. .
When the filler for light-reflecting porous film of the present invention is blended into a resin, it is selected in consideration of them, but a mixture mixed with resin powder having an appropriate particle size range by a Henschel mixer or the like is mixed with a biaxial kneader. A method of quantitatively charging the hopper of a kneader such as the above is preferable.

Between the mixer and film formation, once the pellets containing various additives including the resin for the light reflecting porous film of the present invention, which is called a master batch, are prepared, and then combined with the additive-free resin. To melt and form a film.
Furthermore, if necessary, a plurality of T-die extruders in the above process may be stacked or a process of bonding at the time of stretching may be introduced to form a light reflecting multilayer film.

Hereinafter, the present invention will be described in more detail based on examples, but the scope of the present invention is not limited by these examples.
In the following description, “%” means “% by weight” and “parts” means “parts by weight” unless otherwise specified.

Example 1
Quick lime obtained by baking gray dense limestone with kerosene as a heat source in a fluidized tank kiln is dissolved in water after removing foreign matter with a sieve to form slaked lime slurry, and after removing foreign matter and coarse particles with a cyclone etc. After the reaction, the elution and adsorption of calcium carbonate particles called Ostwald ripening into the water were repeated to perform particle growth, and 10% of precipitated calcium carbonate having a BET specific surface area Swx of 10 m ² / g was obtained. A water slurry was obtained.
Next, as the surfactant (A), an aqueous solution of the surfactant (A) is prepared by dissolving 3.3% of the mixed treatment agent A1 separately prepared with the composition shown below in calcium carbonate solids in 80 ° C. hot water. In addition, sodium hexametaphosphate (reagent grade 1) as a compound having chelating ability with respect to alkaline earth metal (hereinafter referred to as chelating agent ) (B) is 0.9% with respect to calcium carbonate solids as water at 40 ° C. To obtain an aqueous solution of the chelate compound (B).
The precipitating calcium carbonate slurry obtained above was adjusted to 60 ° C. while stirring, and the above-mentioned surfactant (A) and chelate compound (B) were added thereto, and stirred for 4 hours to obtain a surface-treated calcium carbonate slurry. Got.
The surface-treated calcium carbonate slurry was removed with a high-speed decanter manufactured by Tanabe Wiltech Co., Ltd. and a 350 mesh sieve to remove foreign substances and coarse particles, dehydrated, dried and crushed, and the resulting dry powder was air-classified. Classification was performed with a machine to obtain a surface-treated calcium carbonate powder.
The obtained surface-treated calcium carbonate powder had D ₅₀ of 0.476 μm, Dx of 0.15 μm, Da of 1.635 μm, and Sw of 9.3 m ² / g.

Mixed treatment agent A1
Potassium stearate 65%
Sodium palmitate 20%
Sodium laurate 15%

Example 2-5
A water slurry containing 10% of precipitated calcium carbonate having a BET specific surface area of Swxm ² / g was obtained in the same manner as in Example 1, and the same operation as in Example 1 was performed to obtain a surface-treated calcium carbonate powder. .
Various physical properties of the obtained surface-treated calcium carbonate powder are shown in Table 1.

Example 6
A surface-treated calcium carbonate powder was obtained in the same manner as in Example 1 except that the surfactant (A) was changed to a commercially available soap (Non-Sal SK-1 manufactured by Nippon Oil & Fats Co., Ltd.).
Various physical properties of the obtained surface-treated calcium carbonate powder are shown in Table 1. In addition, the typical composition of the used soap is shown below.
Non-Sal SK-1
Potassium palmitate 27.4%
Potassium stearate 65.6%
Potassium alkydate 1.4%
Potassium behenate 1.0%
Potassium myristate 2.0%
Other 2.6%

Example 7
A surface-treated calcium carbonate powder was obtained in the same manner as in Example 1 except that the surfactant (A) was changed to potassium stearate.
Various physical properties of the obtained surface-treated calcium carbonate powder are shown in Table 1.

Example 8
A surface-treated calcium carbonate powder was obtained in the same manner as in Example 1 except that the surfactant (A) was changed to sodium laurate.
Table 2 shows various physical properties of the obtained surface-treated calcium carbonate powder .

Example 9
A surface-treated calcium carbonate powder was obtained in the same manner as in Example 1 except that the amount of surfactant (A) added to calcium carbonate was changed to 10%.
Table 2 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Example 10
A surface-treated calcium carbonate powder was obtained in the same manner as in Example 1 except that the addition amounts of the surfactant A1 and the chelating agent (B) to calcium carbonate were changed to 3.6% and 2.5%, respectively.
Table 2 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Comparative Example 1
A surface-treated calcium carbonate powder was obtained in the same manner as in Example 1 except that the chelating agent (B) was not added as a treating agent.
Table 3 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Comparative Example 2
A surface-treated calcium carbonate powder was obtained in the same manner as in Example 1 except that the surfactant (A) was not added as a treating agent.
Table 3 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Comparative Example 3
Example 1 except that the BET specific surface area of the precipitated calcium carbonate slurry was changed to 38 m ² / g and the addition amounts of the surfactant (A) and the chelating agent (B) were changed to 12.5% and 3.7%, respectively. The same operation was performed to obtain a surface-treated calcium carbonate powder.
Table 3 shows various physical properties of the obtained surface-treated calcium carbonate powder .

Comparative Example 4
A surface-treated calcium carbonate powder was obtained in the same manner as in Example 1 except that the surfactant (A) was changed to sodium oleate.
Table 3 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Comparative Example 5
A surface-treated calcium carbonate powder was obtained in the same manner as in Example 1 except that the surfactant (A) was changed to sodium abietic acid.
Table 3 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Comparative Example 6
A surface-treated calcium carbonate powder was obtained in the same manner as in Example 1 except that the chelating agent (B) was changed to sodium polyacrylate.
Table 3 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Comparative Example 7
Except changing the chelating agent (B) to polyaluminum chloride, the same operation as in Example 1 was performed to obtain a surface-treated calcium carbonate powder.
Table 3 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Comparative Example 8
Surface treatment calcium carbonate was carried out in the same manner as in Example 1 except that the aging after the reaction was not performed and the addition amounts of the surfactant (A) and the chelating agent (B) were changed to 5% and 1.8%, respectively. A powder was obtained.
Table 3 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Comparative Example 9
In accordance with the method described in JP-A-7-196316, 100 L of a 1.5 mol / L sodium carbonate solution, 100 L of a 1.35 mol / L calcium chloride solution, and a 0.04 mol / L sodium hydroxide solution were prepared. The solution and sodium hydroxide solution were mixed, and the mixed solution and calcium chloride solution were adjusted to 16.0 ° C., respectively.
To 200 L of a mixed solution of sodium carbonate solution and sodium hydroxide solution under stirring, 100 L of calcium chloride solution is dropped over 200 seconds, and after 180 seconds from completion of dropping, it is equivalent to 0.36% of calcium carbonate theoretically generated by the reaction. An amount of sodium hexametaphosphate was added and stirred for an additional 5 minutes.
The obtained calcium carbonate slurry was dehydrated and diluted with a high-speed decanter, etc. to remove counter ions and foreign matter, and adjusted to 60 ° C. At the same time, the mixed treatment agent A1 was 1.11% of the calcium carbonate solid content at 80 ° C. An aqueous solution of surfactant (A) was prepared by dissolving in hot water and added to the calcium carbonate slurry, and stirred for 4 hours to obtain a surface-treated calcium carbonate slurry.
The obtained surface-treated calcium carbonate slurry was dried and crushed, and the obtained dry powder was classified with an air classifier to obtain a surface-treated calcium carbonate powder.
Table 3 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Comparative Example 10
A surface-treated calcium carbonate powder was obtained by performing the same operation as in Example 1 except that coke was used as a heat source and gray dense limestone was fired in a shaft kiln and the foreign matter removal step was not performed.
Table 3 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Comparative Example 11
A white sugar crystalline limestone is mixed with water to prepare a 10% slurry, and the slurry is wet pulverized with a wet pulverizer Dynomill KB-20B to obtain a BET specific surface area of 1.2 m. ² / G calcium carbonate water slurry was obtained.
Next, 0.8% of the calcium carbonate solid content is dissolved in 80 ° C. hot water in the calcium carbonate aqueous slurry, with the mixed treatment agent A1 separately prepared with the composition shown below as the surfactant (A). Then, an aqueous solution of the surfactant (A) is obtained. Further, as a chelating agent (B), sodium hexametaphosphate (reagent grade 1) is dissolved in 0.3% of calcium carbonate solids in 40 ° C. water to form a chelate compound (B ) Was obtained.
The precipitating calcium carbonate slurry obtained above is adjusted to 60 ° C. while stirring, and the above-mentioned surfactant (A) and chelating agent (B) are added to this, and the surface-treated calcium carbonate slurry is stirred for 4 hours. Got.
The surface-treated calcium carbonate slurry was removed with a high-speed decanter manufactured by Tanabe Wiltech Co., Ltd. and a 350 mesh sieve to remove foreign substances and coarse particles, dehydrated, dried and crushed, and the resulting dry powder was air-classified. Classifying with a machine to obtain surface-treated calcium carbonate powder
  Table 3 shows various physical properties of the obtained surface-treated calcium carbonate powder.

Examples 11-20, Comparative Examples 12 to 22
Light-reflecting porous material comprising 100 parts of polypropylene resin (FS2011DG2, manufactured by Sumitomo Chemical Co., Ltd., MI = 2.0 g / 10 min), Examples 1 to 10 and Comparative Examples 1 to 11 and surface-treated calcium carbonate powder. 110 parts of filler for quality film and 1 part of calcium stearate were charged into a Henschel mixer and mixed for 5 minutes to obtain a filler-resin mixture.
The obtained mixture was processed into a pellet form by a vent type twin screw extruder. The pellets were used to obtain an unstretched sheet using an extruder equipped with a T die. The obtained unstretched sheet was stretched about 7 times in a tenter oven at a temperature of 140 ° C. to obtain a 180 μm porous stretched film.

A polyester hot melt adhesive was applied to the obtained porous stretched sheet with a thickness of 7 μm with a gravure coater. A 200 μm thick aluminum sheet, which is a plate-like support, was laminated at a temperature of 75 ° C. to the porous stretched sheet coated with this adhesive to obtain a light reflector. At this time, the adhesive strength was 100 g / cm ² .

The light reflector thus obtained was measured and evaluated for density, porosity, total light reflectance, luminance unevenness, and discoloration (yellowing) during continuous lighting. The porosity was determined by the following formula.
Porosity (%) = [(ρ ₀ −ρ) / ρ ₀ ] × 100
However, ρ ₀ represents the true density of the support, and ρ represents the density of the support (JIS-SP-8118). Unless the material before stretching contains a large amount of air, the true density is approximately equal to the density before stretching.
The total light reflectance was obtained by calculating the average value of the reflectance of each wavelength measured in the wavelength range of 40 nm to 700 nm according to JIS-Z-8701. Furthermore, a high temperature environment test (endurance test) was performed using this light reflector, and the change in total light reflectance was measured.

For the evaluation of the luminance unevenness, a 24-inch type surface light source display device of a direct type as shown in FIG. 1 was used. In this apparatus, the light reflector 1 obtained in Examples 11 to 20 and Comparative Examples 12 to 22 was molded as a reflector of a surface light source display device, and a cold cathode lamp 2 was provided inside, and an LCD cell 3 on the front. Is installed. This was turned on and irradiated to visually evaluate whether or not luminance unevenness in the front direction was generated, and evaluated according to the following criteria.
○ Uniform brightness and no unevenness.
× There is unevenness.

Discoloration (yellowing) evaluation during continuous lighting was performed using an eye super UV tester SUV-W13 (Iwasaki Electric Co., Ltd.) and irradiated with a metal halide lamp installed at a position 10 cm away from the film surface of the light reflector. Color change ΔEH from each index value measured before and after the test using a colorimeter (S & M color computer, manufactured by Suga Test Instruments Co., Ltd.) after changing the color tone after irradiation for 24 hours at an intensity of 90 mW / cm ² The value was read (JIS-Z-8730) and evaluated according to the following criteria.
◎ Very good with no change in color tone (ΔEH <0.3).
Good color tone with no change (0.3 ≦ ΔEH <1).
X Color tone changes and is poor (ΔEH ≧ 1).
Overall rating 5 Very good.
4 Good.
3 No problem in use.
2 There are some problems in use.
1 There is a problem in use.

  As described above, the filler for a light-reflecting porous film of the present invention is easily mixed with a resin and has good dispersibility in the resin. For example, a light reflector for a liquid crystal display device or a lighting device. A light-reflecting porous film useful as the above can be provided.

It is the schematic of the direct type backlight unit used for evaluation of brightness nonuniformity.

1 Light Reflector 2 Cold Cathode Lamp 3 LCD Cell 4 Housing (Light Reflector)

Claims (11)

Inorganic particles containing alkaline earth metals are saturated fatty acids, alicyclic carboxylic acids, aromatic sulfonic acids, salts thereof, esters thereof, alcohol surfactants, sorbitan fatty acid esters, amide surfactants, At least one interface selected from amine surfactants, polyoxyalkylene alkyl ethers, polyoxyethylene nonylphenyl ether, alpha-olefin sodium sulfonate, long-chain alkyl amino acids, amine oxides, alkylamines, and quaternary ammonium salts active agent (a), condensed phosphoric acid, at least one selected from a salt thereof, will be surface treated out with a compound having a chelating ability against an alkaline earth metal (B), the surface treatment is the inorganic In a slurry of particles, in the presence of the compound (B), the surfactant (A ), And satisfying the following particle size characteristics (1) to (4):
(1) 0.3 ≦ D ₅₀ ≦ 1.5 [μm]
(2) 0.02 ≦ Dx ≦ 0.6 [μm]
(3) Da ≦ 20 [μm]
(4) 3 ≦ Sw ≦ 20 [m ² / g]
However, D ₅₀ : Cumulative average particle diameter on a sieve [μm] measured with Leeds & Northrup Microtrac FRA (Microtrac)
Dx: Observation with a scanning electron microscope at a magnification of 20,000 times, arbitrarily select 100 particles, and remove the average particle size from the maximum and minimum 20 particles each [μm]
Da: Maximum particle size [μm] measured by Microtrac FRA (Microtrac) manufactured by Leeds & Northrup
Sw: BET specific surface area by nitrogen adsorption method [m ² / g]   The filler for a light reflecting porous film according to claim 1, wherein the inorganic particles are calcium carbonate or barium sulfate.   The filler for a light reflecting porous film according to claim 1 or 2, wherein the surfactant (A) is a fatty acid salt.   The surfactant (A) has a composition containing 50 to 98% by weight of a linear fatty acid salt having 16 or more carbon atoms and 2 to 50% by weight of a linear fatty acid salt having 10 to 14 carbon atoms. Item 4. The filler for a light reflecting porous film according to any one of Items 1 to 3.   The light reflection according to any one of claims 1 to 4, wherein the condensed phosphoric acid of the compound (B) having a chelating ability with respect to an alkaline earth metal is a cyclic condensed phosphoric acid or a metaphosphoric acid. Filler for porous film.   The surfactant (A) is 0.1 to 15% by weight with respect to the inorganic particles, and the compound (B) having chelating ability with respect to the alkaline earth metal is 0.05 to 5% by weight. The filler for light reflecting porous films according to any one of 5. A light-reflecting porous film comprising the resin-filled filler for light-reflecting porous film according to any one of claims 1 to 6 . The light-reflecting porous film according to claim 7 , wherein the blending amount of the filler for light-reflecting porous film is 60 to 150 parts by weight with respect to 100 parts by weight of the resin. Light reflective porous film according to claim 7 or 8, wherein the resin is characterized in that an olefin-based resin. The light reflecting porous film according to any one of claims 7 to 9 , wherein the light reflecting porous film is used for a light reflector of a liquid crystal display device or a lighting device. The light reflecting porous film according to claim 10 , wherein the light reflecting porous film is used for a light reflecting layer of a light reflector.

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