JP2000239535A - Resin blend solution and light dispersing film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a resin blend solution where an island ingredient having a uniform size of the order of the magnitude of μm and stability to external stress is dispersed by phase separation. SOLUTION: This resin blend solution contains a matrix polymer (cellulose acetate or the like), an insular polymer (cellulose ethers or the like) and a solvent enabling these polymer to be dissolved and forms a sea-island structure due to phase separation. The ratio (ηI/ηS) of viscosity measured at 10 wt.% polymer concentration between an insular polymer solution and a matrix polymer one according to the falling ball method is 3-50 and the average diameter of the insular polymer is 1-50 μm (preferably 3-30 μm). The content of the insular polymer is about 1-20 wt.% in terms of solid content based on the total weight of the polymers. The blend solution can be prepared by blending an insular polymer solution having the polymer concentration CI wt.% with a matrix polymer solution having the polymer concentration CS wt.% in a content ratio (CI/CS) of 0.2-1.5. The resin blend solution is useful for producing light dispersing film or sheet by casting itself.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an incompatible resin blend solution suitable for the production of beads, scattering sheets, composite fibers and the like, a method for producing the same, a light diffusion film or sheet using the blend solution, and a method for producing the same. It relates to a manufacturing method.

[0002]

2. Description of the Related Art A polymer phase separation solution having an island structure having a uniform size on the order of microns is effective for various uses such as production of fine particles having a uniform particle size, light diffusion films, and blended fibers. Very likely as a body. However, without directly adding polymer fine particles,
A method for easily producing such a phase separation solution has not been found yet.

As one method of producing a polymer phase separation solution having a spherical island structure, a sea polymer and an island polymer which are incompatible with each other are mixed with a common solvent of both polymers (each polymer is dissolved). However, there has been proposed a method of forming a liquid-liquid phase separation structure by dissolving and mixing each polymer in a solvent which does not make the polymers compatible with each other. However, in general, the size of the island components is not uniform in such a solution, and the size of the island components is unstable with time because the island components fuse with each other with time. In particular, in a mixed liquid having a liquid-liquid phase separation structure, it is difficult to maintain the shape of the island component particles due to the surface tension due to a slight shear stress acting on the solution, and the island component particles (in particular, having an average diameter of 5 μm)
m or more of the island component particles) are easily split or miniaturized. On the other hand, when industrially treating a polymer blend solution,
Stress acts locally on the blend solution in steps such as liquid feeding and solution casting. Therefore, it is substantially impossible to control the size of the island component particles on the order of several μm to several tens μm.

Further, even when a light diffusion film or sheet is manufactured by casting or the like, the particle size of the island component cannot be controlled due to the action of stress, and the light scattering property fluctuates, and a highly reliable light diffusion film is manufactured. Is difficult to do.

[0005] In order to stabilize the size of the island component with time, it is conceivable to add a compatibilizing agent. However, in this case, the size of the island component is reduced to submicron or less, so that the micrometer (μm ) Not suitable for stabilization above.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to achieve a uniform size in the order of microns,
Another object of the present invention is to provide a phase separation solution having an island structure (particularly, a spherical island structure or the like) whose size is stable even against external stress such as shear stress, and a method for producing the same.

It is another object of the present invention to provide a light diffusion film or sheet in which island component polymers are uniformly dispersed on the order of micrometers. Still another object of the present invention is to provide a method for stably and reliably producing a light diffusion film or sheet in which island component polymers are uniformly dispersed on the order of a micrometer even when external stress acts. It is in.

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has determined that a sea polymer and an island polymer having a specific solution viscosity ratio are soluble in each polymer, and When dissolved in a predetermined concentration using a solvent (sometimes called a common solvent) that is not compatible with each other, and the respective polymer solutions are mixed, the polymer solution as an island component is separated from the polymer solution as a sea component by a micrometer due to phase separation. (Μ
m) A resin blend solution that is dispersed in a uniform size and has a stable island component particle size even when a shear force is applied is obtained. By casting and drying this resin blend solution, good optical properties are obtained. The present inventors have found that an excellent light diffusion film can be obtained, and have completed the present invention.

That is, the resin blend solution of the present invention (tree
Fat mixture) is composed of sea polymer, island polymer,
Sea-island structure due to phase separation, including polymer-soluble solvent
A polymer solution having a polymer concentration of 10
Of falling island polymer solution_I(10) and the polymer
-Falling ball viscosity η of 10% by weight sea polymer solution_s(1
0) and the ratio η_I(10) / η_s(10) is 3 to 50,
The average diameter of the island components is 1 to 50 μm. This resin blur
Solution, the total amount of sea polymer and island polymer
The ratio of the island polymer to the solid content is 0.5 to 2 in terms of solid content.
It may be about 5% by weight. Also, sea polymers are examples
For example, cellulose esters (eg, cellulose tris)
Cellulose acetate, such as acetate)
The solvent is usually a sea polymer or an island polymer.
Are soluble and the sea polymer and the island polymer are
Solvents that are not compatible with water can be used. Such resin blur
For example, seawater solutions, island polymers, and
These polymers contain a solvent that is soluble and
A method for producing a blend solution for forming an island structure, comprising:
The sea polymer and the island polymer have the following formula η_I(10) / η_s(10) = 3-50 (where η_I(10) is a 10% by weight island polymer solution
Shows the falling ball viscosity of η_s(10) is a sea port with a concentration of 10% by weight.
Satisfies the falling ball viscosity of the limmer solution) and polymer
Concentration C_I(Wt%) island polymer solution and polymer concentration C
_s(% By weight) of the sea polymer solution_I/ C_s= 0.
It can be prepared by mixing at 2 to 1.5.

In the method of the present invention, a light diffusing film or sheet can be produced by casting the resin blend solution. The light diffusing film or sheet of the present invention is a film or sheet in which an incompatible island polymer is dispersed in a sea polymer, and the polymer concentration relative to the falling ball viscosity η _s (10) of a sea polymer solution having a polymer concentration of 10% by weight. 10
Η _I ratio of falling ball viscosity η _I (10) of wt% island polymer solution
(10) / η _s (10) is 3 to 50, and the average diameter of the island polymer is 1 to 50 μm.

In the present specification, a sea polymer or a solution thereof is dispersed in a “sea component”, the sea polymer or a solution thereof, and is composed of an island polymer or a solution thereof regardless of whether a solvent is contained or not. The dispersed component obtained may be referred to as an “island component”.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION [Resin Blend Solution] The resin blend solution of the present invention contains a sea polymer (sea component) and an island polymer (island component) incompatible with each other, and a common solvent for these polymers. And form a sea-island structure (dispersed structure) by phase separation. The type of the sea polymer and the island polymer is determined by the relational expression η _I (1
0) / η _s (10) = 3 to 50, not particularly limited, and can be selected from thermoplastic resins and thermosetting resins.
As the sea polymer and the island polymer, a thermoplastic resin soluble in a solvent, particularly an organic solvent can be used.

Among the polymers forming the sea polymer and / or the island polymer, examples of the thermoplastic resin include 1,4-glucan derivative resins having a glucose skeleton (eg, cellulose derivatives such as cellulose esters and cellulose ethers); Olefin-containing resins (ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylate copolymer, etc.), vinyl acetate resin ( Polyvinyl acetate, vinyl acetate-vinyl chloride copolymer, vinyl acetate- (meth) acrylate copolymer, etc.), polyvinyl acetal resin, halogen-containing resin (polyvinyl chloride, vinyl chloride- (meth) acrylate copolymer) Polymerization, vinylidene chloride- (meth) acrylate Etc.), (meth) acrylic resin [(meth) acrylic acid or homo- or copolymer of the ester (polymethyl methacrylate, methyl methacrylate -
(Meth) acrylic acid ester copolymer), (meth)
Copolymer of acrylic monomer and other monomer (methyl methacrylate-styrene copolymer, methyl methacrylate-
(Meth) acrylic acid ester-styrene copolymer, methyl methacrylate- (meth) acrylic acid-styrene copolymer)], styrene-based resin [only or copolymer of styrene-based monomer (such as polystyrene), Copolymers of styrene monomers and other monomers (styrene- (meth) acrylate copolymer, styrene- (meth) acrylic acid copolymer, styrene-maleic anhydride copolymer, styrene -Acrylonitrile copolymer)], polyester resins (aromatic polyesters using aromatic dicarboxylic acids such as terephthalic acid, aliphatic polyesters using aliphatic dicarboxylic acids such as adipic acid), polyamide resins (polyamide 6) , Polyamide 6/10, polyamide 6
/ 11, polyamide 6/12), polycarbonate resins (such as aromatic polycarbonate resins using bisphenols such as bisphenol A, aliphatic polycarbonate resins such as ethylene glycol bisallyl carbonate), thermoplastic polyurethane resins, polyphenylene ether, Examples thereof include thermoplastic elastomers (polyester elastomer, acrylic elastomer, polyurethane elastomer, olefin elastomer, etc.). Sea and island polymers can be used in any suitable combination.

Preferred sea polymers are film-forming resins,
In particular, the polymer can be made of a highly transparent resin. For example, the sea polymer and the island polymer can be made of the glucan derivative resin (particularly, a cellulose derivative).

Glucan derivative resins include various resins derived from polysaccharides composed of glucose (eg, cellulose, starch, glycogen, laminaran, lichenin, dextran, nigeran, etc.). The cellulose derivatives are generally classified into cellulose esters, cellulose carbamates, and cellulose ethers.

Examples of the cellulose esters include organic acid esters such as aliphatic organic acid esters (C _1-6 such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate). Organic acid esters, dichloromethylcellulose esters, trichloromethylcellulose esters, haloalkylcellulose esters such as trifluoromethylcellulose esters), aromatic organic acid esters (cellulose phthalate,
Cellulose benzoate, C _{7- 12} aromatic carboxylic acid esters such as cellulose 4-methylbenzoate), inorganic acid esters, such as cellulose phosphate, can be exemplified such as cellulose sulfate, organic acids such as acetic cellulose nitrate ester It may be a mixed acid ester of and an inorganic acid. Preferred cellulose esters include cellulose _C2-4 aliphatic carboxylic acid esters (especially cellulose acetate and the like).

The average degree of substitution of cellulose esters is 1
It can be selected from a range of about 3 to 3, for example, cellulose monoacetate, cellulose diacetate, cellulose triacetate and the like. The average degree of substitution of the cellulose ester (particularly cellulose acetate) is from 2 to 3 (for example, from 2.2 to 3), preferably from 2.4 to 2 from the viewpoints of solubility in a solvent and physical properties of a molded product. 95 (for example, 2.5 to 2.95), more preferably 2.7 to
It is about 2.95. Cellulose esters having an average degree of substitution of 2.7 or more (particularly cellulose triacetate) are particularly preferred because of their excellent transparency, sheet strength, and water resistance. When the average degree of substitution exceeds 2.95, the solubility in a solvent tends to be remarkably reduced.

The average degree of polymerization (number average degree of polymerization) of cellulose esters (particularly cellulose acetate) is not particularly limited, and is, for example, 100 to 400, preferably 150 to 400.
It is about 350 (for example, 200 to 350).

Examples of the cellulose carbamates include, for example, cellulose aryl carbamates (eg, cellulose phenyl carbamate), cellulose-halogen substituted aryl carbamates (cellulose-4-chlorophenyl carbamate), and cellulose-alkyl substituted aryl carbamates (cellulose-4-methylphenyl carbamate). , Cellulose-3,5-dimethylphenyl carbamate, amylose-3,5-dimethylphenyl carbamate), cellulose aryl carbamates such as amylose methylbenzylphenyl carbamate, cellulose ester carbamates (such as acetyl cellulose phenyl carbamate), and cellulose ether carbamates (Ethyl cellulose phenyl carbamate and the like).

As the cellulose ethers, for example,
Cyanoalkyl cellulose (cyanoethyl cellulose), hydroxyalkyl -C _1-4 alkyl celluloses (hydroxyethyl cellulose, hydroxy -C _2-4 alkyl celluloses such as hydroxypropyl cellulose), C
_1-10 alkylcellulose (methyl cellulose, C _1-6 alkyl celluloses such as ethyl cellulose), (such as carboxymethyl cellulose or a salt thereof) carboxyalkyl cellulose, C _6-12 aryl -C _1-4 such aralkyl cellulose (base down Jill cellulose And cellulose ethers such as alkyl cellulose) and alkyl cellulose esters (such as acetyl alkyl cellulose).

The average degree of substitution of cellulose carbamates and cellulose ethers is 0.1 to 3, preferably 0.5.
It can be appropriately selected from a wide range of about 2.5. The degree of polymerization (number average degree of polymerization) of the cellulose carbamates and cellulose ethers is not particularly limited.
400, preferably 50 to 350 (for example, 50 to 30
0).

When the sea polymer and the island polymer are composed of a glucan derivative resin (particularly a cellulose derivative), the sea polymer is composed of cellulose esters, and the island polymer is at least one kind of cellulose selected from cellulose carbamates and cellulose ethers. It may be composed of a derivative. When the sea polymer is composed of cellulose acetate, the island polymer may be formed of at least one cellulose derivative selected from cellulose esters other than cellulose acetate, cellulose carbamates and cellulose ethers. Sea polymers (for example, cellulose esters such as cellulose acetate) and island polymers (for example, cellulose ethers) can be used alone or in combination of two or more.

In the present invention, the solution viscosity ratio between the sea polymer and the island polymer has a great influence on the stability of the size of the island polymer. That is, the falling ball viscosity of an island polymer solution having a polymer concentration of 10% by weight is η _I (10), and the falling ball viscosity of a sea polymer solution having a polymer concentration of 10% by weight is η _s (10)
, The solution viscosity ratio η _I (10) / η _s (10) is 3
~ 50, preferably 5 ~ 45, more preferably 10 ~
It is about 40. When the solution viscosity ratio η _I (10) / η _s (10) is less than 3, islands are easily split and miniaturized even when a slight external stress is applied to the solution. It is difficult to disperse uniformly in the polymer solution, and the average diameter of islands of the phase separation solution tends to be large.
In addition, the falling ball viscosity is a value measured at a temperature of 25 ° C., as described in Examples described later.

The solution viscosity ratio can be determined by various methods, for example,
It can be controlled by adjusting the molecular weight of the island polymer and the sea polymer, the type of substituent, the degree of substitution, and the like, and selecting an appropriate solvent.

The proportion of the island polymer is in a range in which the island component can be formed stably according to the type of the sea polymer (for example, 0.5 in terms of solid content relative to the total amount of the sea polymer and the island polymer).
To 30% by weight), for example, 0.5% in terms of solid content based on the total amount of the sea polymer and the island polymer.
About 25% by weight (for example, 1 to 20% by weight), preferably about 1 to 15% by weight (for example, 1 to 13% by weight). If the ratio of the island polymer is too large, the fusion of the island components with time progresses rapidly, and it becomes difficult to control the size of the island component.If the ratio of the island polymer is too small, the dispersed island component of the particle form is reduced. The production efficiency tends to decrease.

As the solvent, any solvent can be used as long as it is a solvent that can dissolve both the island polymer and the sea polymer and does not make these polymers mutually compatible. As the solvent, water or an aqueous solvent can be used, but usually, a volatile solvent (organic solvent) is preferable for producing a film or a sheet by casting. Examples of such a solvent include halogenated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride, ethylene chloride, etc.), esters (methyl formate, methyl acetate, ethyl acetate, butyl acetate, etc.), ketones (acetone, Methyl ethyl ketone, methyl isobutyl ketone, etc.), ethers (ethyl ether, dioxane, tetrahydrofuran, etc.), aromatic hydrocarbons (toluene, cyclohexane, etc.), alcohols (methanol, ethanol, isopropanol, butanol, etc.), cellosolves (methyl cellosolve) , Ethyl cellosolve, butyl cellosolve, etc.), cellosolve acetates (ethyl cellosolve acetate, etc.), carbitols (methyl carbitol, ethyl carbitol, etc.), and the like. These solvents may be used alone. It can be used as a mixed solvent (such as halogenated hydrocarbons / alcohols). As the solvent, a solvent having a common or the same solvent component (common solvent) can be used for each of the sea polymer and the island polymer.

The resin blend solution of the present invention is probably because the sea polymer solution and the island polymer solution are incompatible with each other,
It has a structure (sea-island structure by liquid-liquid phase separation) in which the island polymer solution (island component) is phase-separated and dispersed in the sea polymer solution, and the diameter size (average diameter) of the island component by the phase separation is It is characterized in that it is dispersed almost uniformly and stably in the order of micrometers (μm). The average diameter of the island component is, for example, about 1 to 50 μm, usually 1 to 40 μm (for example, 2 to 35 μm), preferably 2 to 30 μm (for example, 3 to 30 μm), and more preferably 2 to 25 μm (for example, , 3 to 25 μm).

The total polymer concentration in the resin blend solution of the present invention is not particularly limited as long as the stability of the island component is not impaired, and is, for example, 2 to 30% by weight (for example, 3 to 25% by weight), preferably 5 to 25% by weight. About 25% by weight, usually
It is about 5 to 20% by weight. Total polymer concentration is 2% by weight
If it is less than 30% by weight or more than 30% by weight, the size of the island component tends to be unstable with time.

The shape of the island component dispersed in the resin blend solution is not particularly limited, and may be, for example, polyhedral or fibrous. The island component is usually in the form of a sphere or an ellipse. Are often dispersed.

[Method of Preparing Phase Separation Solution] The resin blend solution of the present invention has the above solution viscosity ratio η _I (10) / η _s (10)
Can be prepared by a method of mixing and stirring (or kneading) the sea polymer and the island polymer with the solvent in various modes. For example, (1) a method of mixing the above sea polymer and the island polymer with the solvent, (2) A method of mixing one polymer solution of the sea polymer and the island polymer with the other polymer (for example, a method of adding and mixing an island polymer to a mixed solution of a sea polymer and a solvent), (3) a sea polymer solution And an island polymer solution, respectively, and a method of mixing the obtained polymer solutions can be used. In order to easily and efficiently prepare a resin blend solution, the above method (3) is particularly useful.

In particular, sea and island polymers
Dissolve in each solvent, sea polymer solution and island polymer solution
And polymer concentration C_I(Wt%) island polymer
Solution and polymer concentration C_s(Wt%) sea polymer solution
And C_I/ C_s= 0.2-1.5, preferably 0.2-
1.4 (for example, 0.3 to 1.4), more preferably
Mixing (or kneading) at a concentration ratio of about 0.3 to 1.3
Is preferred. Concentration ratio C ₁/ C_sIs less than 0.2,
Inevitably a large amount of solvent is required to prepare the limmer solution,
The polymer concentration of the resin blend solution decreases and exceeds 1.5
In addition, mixing of island polymer solution and sea polymer solution (or
In the kneading process, the island component (or island po
Dispersion efficiency of the Limmer solution) decreases and the average diameter of the
It is easy to grow, and the average size of the island component is accurately determined
You lose control.

The mixing (kneading) of the island polymer solution and the sea polymer solution can be performed using a conventional mixing or dispersing machine, for example, a screw mixer such as a homogenizer or a mixer, an ultrasonic dispersing machine, or the like. Preferred mixing (kneading) can be performed using a method capable of applying a relatively strong stress (shearing force) to the mixed solution, for example, using a homogenizer (such as a strong homogenizer or a homomixer), screw stirring, or double screw stirring. . The rotation speed of the screw is, for example, 50 to 10000 rpm.
Degree.

The average diameter of the island components in the phase-separated solution thus prepared varies depending on the shearing force, but seems to have, for example, about 1 to 10 μm immediately after mixing or kneading. As a method of controlling the size of the island component, it is possible to control the mixing or kneading strength, but if the mixed liquid is gently stirred (for example, at about 0.1 to 50 rpm) after the mixing or kneading, the stirring time is reduced. Accordingly, the size of the island component gradually increases. Therefore, the size of the island component can be easily controlled by gentle stirring. Further, when the stirring is stopped, the size of the island component stops increasing, and the size of the island component can be stably maintained. Therefore, the phase separation solution having the predetermined island size manufactured by the method of the present invention is stored. Is also easy.

The mixing or kneading time is not particularly limited, but usually, the stability of the island component against external stress can be achieved in about one hour from the start of mixing or kneading. Further, even if a strong shearing force (strong kneading) is applied thereafter, it seems that the island component hardly splits or miniaturizes. for that reason,
From the viewpoint of economy and productivity, the mixing or kneading time is usually sufficient within one hour.

[Light Diffusion Film or Sheet and Method for Producing the Same] In the resin blend solution of the present invention, the size of the island component is stable against external stress, and the dispersion form of the island component in the sea component even when the solvent is removed. (Morphology) seems to be maintained almost as it is. Therefore, the resin blend solution of the present invention is suitable for, for example, producing polymer fine particles of an arbitrary particle size (particularly uniform particle size) by elution of a sea polymer and the like, and as a precursor of a composite fiber or a light diffusion film. Is also useful. Further, in the resin blend solution of the present invention, since the size of the island component is controllable and the island component is stably dispersed, the resin blend solution has a sea-island structure by casting. In addition, a film or sheet capable of controlling light scattering characteristics can be easily manufactured. In particular, when the sea component having the phase separation structure is a resin solution of a cellulose derivative (particularly, a cellulose ester such as cellulose acetate), a film having high visible light transmittance can be easily obtained.

Furthermore, since the island component of the phase separation structure in the resin blend solution of the present invention has an appropriate size as a light scatterer and the size of the island component can be controlled, the sea polymer (for example, cellulose) The refractive index is 0.00 for cellulose esters such as acetate.
1 or more (preferably 0.02 or more, for example, 0.02 to
When about 0.5) different island polymers (for example, cellulose ethers) are used, in particular, a light diffusion (or light scattering) film or sheet which is required to have high transmittance performance, for example, a light of a reflection type liquid crystal display device. Diffusion film (for example,
(For example, a forward scattering sheet disposed on the front side of a reflection type liquid crystal provided with a polarizing plate).

The light-diffusing film or sheet of the present invention has a solid content composition corresponding to the resin friend solution, and contains a sea component polymer having the solution viscosity ratio η _I (10) / η _s (10). It is composed of an island component polymer, and has a form in which an insoluble island polymer is dispersed in the sea polymer. The average diameter (average particle diameter) of the island polymer (island component) can be selected from a range of about 1 to 50 μm, usually 1 to 40 μm, corresponding to the island polymer solution (island component) of the resin blend solution. , Preferably 2-3
0 μm (for example, 3 to 30 μm), more preferably 2 μm
About 25 μm. The shape of the island polymer dispersed in the sea polymer is not particularly limited, and may be, for example, a sphere, an ellipsoid, a polyhedron, a fiber, or the like. Island polymers are often dispersed in forms such as spheres or ellipses.

In the production method of the present invention, a light diffusing film or sheet can be produced by casting the resin blend solution. The casting method is a conventional method, for example, applying the resin blend solution to a support such as a metal (which may be a sheet or a drum), removing at least a part of the solvent, and removing the solvent from the support. It can be performed by peeling the coating film and drying. Further, a thin film may be obtained by applying using a spin coating method in the same manner as described above.

The molded article (film or sheet) thus obtained seems to have a morphology in which the island polymer is dispersed in the sea polymer, and the thickness of the film or sheet depends on the application. For example, 0.1-100
0 μm, preferably in the range of about 1 to 500 μm, usually 5 to 500 μm (particularly 10 to 500 μm)
It is about.

The resin blend solution and the molded product may contain various additives such as stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, etc.), plasticizers, colorants (dye and pigment),
It may contain a flame retardant, an antistatic agent, a surfactant and the like.

[0041]

According to the present invention, since the sea polymer and the island polymer are combined at a specific solution viscosity ratio, the island structure is dispersed in the order of microns and has a stable size with respect to external stress. Phase-separated solution having a spherical island structure). It is also easy to control the average size of the island components. Therefore, this phase separation solution is useful for obtaining a highly reliable light diffusion film or sheet in which island components are uniformly dispersed in the order of micrometers.

[0042]

EXAMPLES The present invention will be described below in more detail with reference to Examples, but the present invention is not limited to these Examples.

The falling ball viscosity η (10) of a polymer solution having a polymer concentration of 10% by weight was measured as follows.
30 parts by weight of the polymer were placed in a container containing 270 parts by weight of the solvent, and the container was rotated overnight (2 rpm) to dissolve the polymer. The obtained polymer solution is poured into a viscosity tube, and 2
An iron hard sphere is dropped at 5 ° C., and the steady speed at which the hard sphere is dropped is measured. The internal diameter of the viscosity tube is D, the density of the hard sphere is d, the density of the hard sphere is ρ, the density of the solution is ρ ′, the steady speed of the drop is r,
Assuming that the weight acceleration is g, the viscosity can be obtained from the following equation.

Η = [gd ² (ρ-ρ ') r / 18] x
[1-2.104 (d / D) +2.09 (d / D) ³ -0.95 (d
/ D) ⁵ ] Example 1 Cellulose triacetate (average degree of substitution 2.86)
It was dissolved in methylene chloride / methanol (9/1, weight ratio) to prepare 653 parts by weight of a cellulose triacetate solution (sea polymer solution) having a polymer concentration of C _s = 15% by weight. On the other hand, hydroxypropyl cellulose (manufactured by Nippon Soda Co., Ltd., trade name M) was dissolved in methylene chloride / methanol (9/1, weight ratio), and the polymer concentration C _I = 10.
20 parts by weight of a hydroxypropylcellulose solution of 20% by weight (island polymer solution) was prepared. The concentration ratio of the solution C
_I / C _s = 0.67.

The falling ball viscosity η _s (10) of the 10 wt% cellulose triacetate solution is 3 Pa · s, and the falling ball viscosity η _{I of the} 10 wt% hydroxypropyl cellulose solution is
(10) is 120 Pa · s, and η _I (10) / η _s (1
0) = 40.

The sea polymer solution and the island polymer solution were mixed and kneaded with a screw at 1,000 rpm for 5 minutes. After kneading, the mixed solution was rotated 1.5 times.
The mixture was stirred at rpm for 5 hours, and the average diameter of the island component of the polymer mixture was observed with an optical microscope. The results shown in Table 1 were obtained.

Further, in order to evaluate the stability of the island component against the shearing force, a polymer mixture is dropped on a glass plate, cast at a speed of 5 cm / sec using a bar coater with a clearance of 1 mm, and dried. To prepare a sheet.
Observing the cross section of this sheet with an optical microscope, and measuring the average diameter of the island component between the sheet surface where a strong shearing force acts during film formation by casting and the inside of the sheet where a large shearing force does not act during casting, The results shown in Table 1 were obtained.

As is apparent from Table 1, since the average diameter of the island component hardly changes between the surface and the inside of the sheet prepared by casting the polymer mixture, the size of the island component in the polymer mixture is small. Stable against external stress.

COMPARATIVE EXAMPLE 1 The polymer concentration C _{s of the} cellulose triacetate solution (sea polymer solution) was set to 7.5% by weight, and the polymer concentration C of the hydroxypropyl cellulose solution (island polymer solution) was determined.
_A polymer mixture and a sheet were prepared in the same manner as in Example 1 except that _I = 12.5% by weight (concentration ratio C _I / C _s = 1.67), and the size of the island component of the sheet was measured.
As is clear from Table 1, the island polymer solution could not be uniformly dispersed in the sea polymer solution, and an island component having a uniform size on the order of micrometers could not be formed.

Comparative Example 2 A polymethyl methacrylate (PMMA) solution (a sea polymer solution having a polymer concentration of C _s = 17.5% by weight) and a cyanoethyl cellulose (CEC) (trade name M, manufactured by Nippon Soda Co., Ltd.) A solution (island polymer solution having a polymer concentration C _I = 12.5% by weight) was prepared (concentration ratio C _I / C _s = 0.6).
Except for 7), a polymer mixture and a sheet were prepared in the same manner as in Example 1. The falling ball viscosity η _s (10) of a 10% by weight PMMA solution is 0.2 Pa · s, 10% by weight.
The falling ball viscosity η _I (10) of the CEC solution is 15 Pa · s, and η _I (10) / η _s (10) = 75.

As apparent from Table 1, the island polymer solution could not be uniformly dispersed in the sea polymer solution, and an island component having a uniform size on the order of micrometers could not be formed. Comparative Example 3 A polymethyl methacrylate (PMMA) solution (a sea polymer solution having a polymer concentration of C _s = 20% by weight) and a methyl methacrylate-styrene copolymer (Daicel Chemical Industries, Ltd.)
(Mass methacrylate (60) -styrene (40) copolymer, trade name MAS10) (polymer concentration C _I = 2)
0% by weight of an island polymer solution) (concentration ratio C _I /
C _s = 1), except that the proportion of the island polymer 5% by weight of the total polymer and (in terms of solid content), to prepare a polymer mixture and sheets in the same manner as in Example 1. The falling ball viscosity η _s (10) of a 10% by weight PMMA solution is 0.2 Pa ·
s, falling ball viscosity η _{I of} 10% by weight MS-40 solution (10)
Is 0.2 Pa · s, and η _I (10) / η _s (10) = 1
It is.

As is clear from Table 1, the average diameter of the island component in the solution is 6 μm, the average diameter of the island component on the sheet surface obtained by casting the solution is 2 μm, and the The size of the island component is unstable.

[0053]

[Table 1]

Examples 2 to 5 As a sea polymer solution, cellulose triacetate (C
TA) (LT-55, manufactured by Daicel Chemical Industries, Ltd.)
Dissolved in methylene chloride / methanol = 9/1 (weight ratio)
135 parts by weight of a 7.5% by weight CTA solution were prepared. one
On the other hand, as an island polymer solution, cyanoethyl cellulose
(CEC) (Tokyo Kasei Co., Ltd., cyanoethylation degree 47)
%) With the same mixed solvent as above (methylene chloride / methanol
= 9/1) and a 7.5% by weight CEC solution 15
Parts by weight (concentration ratio C_I/ C _s= 1). In addition, 1
Falling ball viscosity ratio η of 0 wt% CTA solution_s(10) is 3P
a · s, falling ball viscosity η of a 10% by weight CEC solution₁(1
0) is 15 Pa · s, and the viscosity ratio η₁(10) / η
_s(10) = 5.

After the CTA solution and the CEC solution were mixed and kneaded with a screw at 1,000 rpm for 5 minutes, the polymer mixed solution was rotated at 1.5 rpm for a predetermined time (0 hour, 1 hour, 5 hours, 72 hours). Time)
The average diameter of the island component of each polymer mixed solution was observed with an optical microscope.

Further, in order to evaluate the stability of the size of the island component against the shearing force, a polymer mixed solution was dropped on a glass plate, and a bar coater having a clearance of 1 mm was used.
A sheet was prepared by casting at a speed of m / sec and drying. Observing the cross section of this sheet with an optical microscope, and measuring the average diameter of the island component between the sheet surface where a strong shearing force acts during film formation by casting and the inside of the sheet where a large shearing force does not act during casting, The results shown in Table 2 were obtained.

As is clear from Table 2, the size of the island component increases with the elapse of the stirring time, and it can be seen that the size can be controlled by the stirring time. Table 2
In the sheet prepared by casting the mixed solution, the size of the island component does not change at all between the inside and the surface, indicating that the size of the island component is stable against external stress.

[0058]

[Table 2]

Comparative Example 4 and Examples 6-9 Except for changing the polymer concentration ratio C _I / C _S by changing the polymer concentration Cs of the CTA solution as the sea polymer,
A polymer solution and a sheet were prepared in the same manner as in Example 5, and the island component was evaluated. Table 3 shows the results.

As shown in Table 3, as the value of the concentration ratio C _I / C _S decreases, the average diameter of the island component decreases. This is because the polymer concentration of the phase separation solution and the average diameter of the island component have a negative relationship. Further, from Comparative Example 4, when the value of the concentration ratio C _I / C _S exceeds 1.5, the dispersibility decreases, and it is difficult to form an island component having an average diameter of the order of several μm to several tens μm. is there. In the examples, since the size of the island component did not change at all between the inside and the surface of the sheet produced by casting the solution, it can be seen that the size of the island component is stable against external stress.

[0061]

[Table 3]

Examples 10 to 13 Polymer concentration C _S of CTA solution as sea polymer solution
10 wt%, except the polymer concentration C ₁ of the CEC solution as the island polymer solution and 12.5 wt% (i.e., the concentration ratio _{C 1 / C S = 1.25)} , in the same manner as in Example 2 kneading After a predetermined time (0 hour, 0.7 hour, 1.4
(Time, 4 hours) to produce a mixed solution and a sheet, and the island component of the obtained sheet was evaluated. Table 4 shows the results.

As is evident from Table 4, the size of the island component increases with the stirring time, and the size can be controlled by the stirring time, as in the tendency shown in Table 2. In addition, in the sheet prepared by casting the mixed solution, the size of the island component on the inside and the surface did not change at all, indicating that the size of the island component was stable against external stress.

[0064]

[Table 4]

Example 14 After the mixed solution obtained in Example 11 was allowed to stand for 72 hours,
When the average diameter of the island component of the mixed solution was measured, 12 μm was obtained.
m. This indicates that the island component size of the resin blend solution of the present invention hardly changes as long as it is allowed to stand. Therefore, the resin blend solution of the present invention can be stored while maintaining the island component at a specific average diameter.

Example 15 The mixed solution obtained in Example 4 was cast and dried to a thickness of 1
A sheet of 00 μm was produced. The total light transmittance and haze of this sheet were measured using a haze meter (NDH-300A, manufactured by Nippon Denshoku Industries Co., Ltd.), and were found to be 91.2% and 51.3%, respectively. In addition, light scattering was measured by NIHON KAGAKU ENG. The monochromatic laser beam emitted from NEO-20MS manufactured by Nissan Co., Ltd. was applied to the front of the sheet, and the scattering spectrum was measured for angles up to a scattering angle of 50 °. FIG. 1 shows the obtained light scattering spectrum. From these results, it can be seen that by casting the phase separation solution of the present invention, it is possible to produce a transmission-type scattering sheet that is comparable to or better than the conventional product.

[Brief description of the drawings]

FIG. 1 is a graph showing a light scattering spectrum of a sheet obtained in Example 15.

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Claims (7)

[Claims] 1. A blend solution containing a sea polymer, an island polymer, and a solvent in which these polymers are soluble, and forming a sea-island structure by phase separation, wherein the falling ball of an island polymer solution having a polymer concentration of 10% by weight is dropped. The viscosity η _I (10) and the falling ball viscosity η _s (1
0) and the ratio η _I (10) / η _s (10) is 3 to 50,
A resin blend solution in which the average diameter of the island components is 1 to 50 μm. 2. The resin blend solution according to claim 1, wherein the ratio of the island polymer to the total amount of the sea polymer and the island polymer is 0.5 to 25% by weight in terms of solid content. 3. The resin blend solution according to claim 1, wherein the sea polymer is cellulose triacetate. 4. A blended liquid containing a cellulose ester as a sea polymer, an island polymer, and a solvent in which these polymers are soluble, and a falling ball viscosity η _s (10) of a cellulose ester solution having a polymer concentration of 10% by weight. And the falling ball viscosity η ₁ (10) of the island polymer solution having a polymer concentration of 10% by weight
Η _I (10) / η _s (10) is 3 to 50, the ratio of the island polymer to the total amount of the sea polymer and the island polymer is 1 to 20% by weight in terms of solid content, and the island component A resin blend solution having an average diameter of 3 to 30 μm. 5. A sea polymer, an island polymer, and a polymer thereof.
Sea-island structure due to phase separation, including polymer-soluble solvent
A method for producing a blend solution that forms
Rimmer and island polymer are represented by the following formula η_I(10) / η_s(10) = 3-50 (where η_I(10) is a 10% by weight island polymer solution
Shows the falling ball viscosity of η_s(10) is a sea port with a concentration of 10% by weight.
Satisfies the falling ball viscosity of the limmer solution) and polymer
Concentration C_I(Wt%) island polymer solution and polymer concentration C
_s(% By weight) of the sea polymer solution_I/ C_s= 0.
A method for producing a resin blend solution mixed in 2 to 1.5. 6. A method for producing a light-diffusing film or sheet by casting the resin blend solution according to claim 1. 7. A film or sheet in which an incompatible island polymer is dispersed in a sea polymer, and has a polymer concentration of 10
The falling ball viscosity η of the 10% by weight polymer solution relative to the falling ball viscosity η _s (10) of the sea polymer solution of 10% by weight
_A light-diffusing film or sheet wherein the ratio η _I (10) / η _s (10) of I (10) is 3 to 50 and the average diameter of the island polymer is 1 to 50 μm.