JPS62260811A - Production of aqueous polyurethane dispersion - Google Patents

Abstract

PURPOSE:To obtain an aqueous polyurethane dispersion excellent in storage stability and mechanical stability and also excellent in the water resistance and chemical resistance of a film obtained therefrom, by reacting a specified monohydroxy compound in forming a polyurethane substance by reacting an active hydrogen-containing compound with an organic polyisocyanate. CONSTITUTION:An aqueous polyurethane dispersion is obtained by producing a polyurethane substance by reacting an active hydrogen-containing compound with an organic polyisocyanate compound and adding water to the produced polyurethane substance. In the production of said polyurethane substance, the following compound is reacted in an amount of 1-30pts.wt. per 100pts.wt. (in terms of solids) obtained polyurethane substance. Said compound is a monohydroxy compound having an oxyethylene unit and at least either of an oxypropylene unit and an oxybutylene unit as structural units, terminated with -OH or -R (wherein R is a 1-20C alkyl group) and having a total oxyethylene unit content >=60wt% based on the total oxyalkylenes.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for producing an aqueous dispersion of a high molecular weight polyurethane resin that does not contain an emulsifier and is useful for paints, fibers, adhesives, etc. It has excellent storage stability, mechanical stability, and compatibility with other resins, inorganic and organic pigments, fillers, etc., and the resulting coating has excellent chemical resistance, especially acid resistance, alkali resistance, and water resistance. The present invention relates to a method for producing an aqueous polyurethane dispersion having the following properties.

[Prior Art] Various methods for producing aqueous dispersions of high molecular weight polyurethane that do not contain emulsifiers have already been proposed6. A compound having a basic tertiary amine group that can be neutralized or quaternized with alcohol, a carboxylic acid group capable of forming a salt, or a compound having high sulfone resistance is contained therein. A known method is to form a salt before or during the addition of water to a polyurethane material to make the polyurethane material water-soluble or water-dispersible. In this method, depending on the degree of hydrophilicity of the salt-formed polyurethane, a molecularly dispersed distribution or a colloidally dispersed distribution is obtained, respectively, intermediate states between a slightly opaque solution and a milky emulsion being created. .

[Problems to be Solved by the Invention] However, polyurethane resins that are water-dispersed by the action of the salt type J& group do not contain emulsifiers and the film shows good water resistance. has anionic or cationic properties, and as a result has the disadvantage that the chemical resistance of the film, particularly acid resistance and alkali resistance, are significantly deteriorated or both or either one thereof.

In addition, it is easily affected by various salts such as polyvalent metal salts, and as a result, its compatibility with other resins, organic and inorganic pigments, fillers, etc. is extremely poor, and its fruiting applications are severely limited, which is a major drawback. have. For this reason, there has been a long-awaited demand for a high molecular weight aqueous polyurethane dispersion that is nonionic and does not contain an emulsifier, without the above-mentioned drawbacks.

Under such circumstances, the inventors of the present invention have found that the resulting film has excellent storage stability, mechanical stability, and compatibility with other resins, inorganic and organic pigments, fillers, etc., and also has excellent water resistance and chemical resistance. The present invention was achieved through intensive research into the synthesis of a high molecular weight polyurethane aqueous dispersion that is nonionic and does not contain an emulsifier.

[Means for solving problems] The present invention is.

(A) has at least two active hydrogen atoms capable of reacting with isocyanate groups in the molecule and has a molecular weight of 300 to 20
000 active hydrogen-containing compound and (E) an organic polyisocyanate compound to produce a polyurethane material, and then adding water, when producing the polyurethane material, (C ) The constituent units are oxyethylene units and at least one of oxypropylene units and oxybutylene units, and the terminals are -OH and -R (R represents an alkyl group having 1 to 20 carbon atoms). A monohydroxy compound having a total unit molecular weight of oxyethylene units of 2,500 to 15,000, and a total content of oxyethylene units of 60% of all oxyalkylenes.
This is a method for producing an aqueous polyurethane dispersion, characterized by reacting the compound in an amount of 1 to 30 parts by weight with respect to 100 parts by weight of solid content of the resulting polyurethane material.

Active hydrogen-containing compounds having at least two active hydrogen atoms capable of reacting with isocyanate in the molecules of suitable component (A) used in the method of the present invention and having molecules B3oo to 20,000 are generally directly used. Chain-like, molecular weight 300
-20,000, preferably 500-4,000.

Such compounds include polyhydroxy compounds containing terminal hydroxyl, carboxyl, amino or mercapto groups, such as polyesters, polyacetals, polyethers, polythioethers, polyamides and polyesteramides.

Examples of polyethers include ethylene oxide, propylene oxide, and tetrahydrofuran.

Polymerization products and copolymerization or graft polymerization products of butylene oxide, and polyethers obtained by polymerization of polyhydric alcohols or mixtures thereof with polyhydric alcohols, amines, polyamines, and amino alcohols are mentioned. I can do it.

Examples of polyacetals include compounds that can be produced from hexanediol and formaldehyde.

As polythioethers, mention may be made in particular of polymerization products of thiodiglycol and of mixtures of thiodiglycol with other glycols or polyhydroxy compounds.

Polyesters, polyesteramides and polyamides include polyvalent saturated and unsaturated carboxylic acids, polyvalent saturated and unsaturated alcohols, amino alcohols,
Mention may be made of those obtained from diamines, polyamines and mixtures thereof, in which linear condensates predominate, as well as, for example, polyterephthalates or polycarbonates.

Alternatively, polyhydroxy compounds containing urethane or urea groups as well as natural polyols, including optionally modified ones such as castor oil and carbohydrates, can also be used.

Mixtures of different polyhydroxy compounds can be added to modify the hydrophilic and hydrophobic properties and physical properties of the products according to the process of the invention.

Examples of the organic polyisocyanate compound as component (B) used in the present invention include 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, dialkyldiphenylmethane diisocyanate, Isomers of tetraalkyldiphenylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, toluylene diisocyanate,
optionally mixtures thereof, all aromatic compounds such as chlorinated and brominated diisocyanates, phosphorous-containing diisocyanates, butane-1,4-diisocyanate, hexane-IJ-diisocyanate, dicyclohexylmethane diisocyanate, cyclohexane-1,4-diisocyanate. and aliphatic diisocyanates are suitable.

Particularly preferably dimers of, for example, toluylene diisocyanate or, for example, phenol, tertiary butanol,
It is possible to use partially capped polyisocyanates which themselves are capable of forming crosslinked polyurethanes, such as polyisocyanates partially reacted with phthalimide or caprolactam.

Typical monohydroxy compounds as component (C) used in the present invention include a monoalcohol having 1 to 20 carbon atoms, preferably 1 to 4 carbon atoms, ethylene oxide alone,
Alternatively, it is a compound obtained by adding ethylene oxide and propylene oxide and/or butylene oxide. At that time, the total molecular weight of the polyoxyethylene part, that is, the oxyethylene unit, is 2500 to 150.
00, preferably 3,000 to 10,000, more preferably 3,000 to 8,000, and the polyoxyethylene portion, that is, the proportion of the total oxyethylene units to the total oxyalkylene units, is 60% by weight or more,
Preferably 70% by weight or more, more preferably 75% by weight
As described above, one end group is an alkyl group having 1 to 20 carbon atoms, created by block polymerization or random polymerization of ethylene oxide alone, or ethylene oxide and propylene oxide and/or butylene oxide. It is a polyoxyalkylene compound in which the other end is a hydroxyl group.

Furthermore, in the present invention, when producing the polyurethane material,
In addition to the above-mentioned components, a chain extender having an active hydrogen atom capable of reacting with the isocyanate group (D) component may be added as appropriate. As such component (D).

1. Particularly advantageous for the process of the invention, such as ethylene glycol or condensates of ethylene glycol, butanediol, propanediol-1,2, propanediol-1,
3. Glycols such as neopentyl glycol, hexanediol, bis-hydroxymethyl-cyclohexane, dioxyethyldian, such as N-methylgetanolamine, N-butylgetanolamine, N,N-
Bis-γ-7minoprobyl-N-methylamine, N-oleylgetanolamine, N-cyclohexyldiisopropanolamine, N,N-dioxyethyl-P-)
Luidine, N,N-dioxypropylnaphthyramine, polyethoxylated N-butylgetanolamine, polypropylated N-methyl-getanolamine (molecular weight 300-4000), polyester with tertiary amino group, dimethyl - hepano- or bis-alkoxylated aliphatic, such as bis-oxyethyl-hydrazine;
Mention may be made of cycloaliphatic, aromatic and heterocyclic primary amines, and also unsaturated glycols such as butanediol, or glycerin heptanoalkyl ether, and 2, such as ethylenediamine, hexamethylenediamine. , 1,4-cyclohexylene diamine, pentidine, diaminodiphenylmethane, aliphatic, cycloaliphatic and aromatic diamines such as isomers of phenylene diamine, and also hydrazine.

Mention may be made of ammonia and carbohydrazides and 3, amino alcohols such as ethanolamine, propatoolamine, butanolamine, and 4, water.

In addition, it is of course possible to use various salt-forming monomers that have been conventionally used to create aqueous polyurethane dispersions that do not contain emulsifiers.A typical example is N-methyljetanolaminodimethylol. Examples include propionic acid, hydroquineethanolsulfonic acid, 1,3-propanesultone, and the like.

The polyurethane material is produced in a manner known per se in the presence or absence of a solvent, with the monohydroxy compound (C) being added at any point during the reaction. The ratio between the total number of isocyanate groups and the total number of reactive hydrogen atoms is dictated by the requirement that a polyurethane material that is soluble in organic solvents be produced. According to this, the molar ratio of isocyanate groups to groups containing active hydrogen atoms is generally 0.4:1-1,5:1. 0.9:1~
A ratio of between 1.2:1 is preferred, generally first adding (B Component (C) is added to produce a preadduct, and then this preadduct is optionally reacted with the chain extender of component (D) in a solvent. In the present invention, component (C) is Because of their monofunctionality, it is generally preferred to use tri- or polyfunctional components such as glycerin or trimethylolpropane, water, diamines or polyisocyanates in the reaction system.

The total molecular weight of the oxyethylene units in component (C) used here is within the range of 2,500 to 15,000, and the total content of the oxyethylene units must be 60 weight or more of the total oxyalkylene. If the sum of the molecular weights is less than 2,500, water dispersion of the resulting polyurethane material is insufficient, and conversely, if it exceeds 15,000, the number of hydroxyl groups per unit molecular weight in the wood-philic monohydroxy compound is extremely low. In this case as well, the water dispersion effect of the polyurethane substance is significantly reduced due to the small size, which is not preferable.

Furthermore, the proportion of polyoxyethylene moieties (ogishethylene units) in the polyoxyalkylene moieties (out of all oxyalkylene units) in the monohydroxy compound is 60
If it is less than % by weight, the degree of lignophilization of the monohydroxy compound decreases, and in this case also, the water dispersibility of the resulting polyurethane material decreases, which is not preferable.

In addition, in the present invention, the amount of the monohydroxy compound (C) added is 10% of the solid content of the polyurethane material obtained.
The reaction is carried out at a ratio of 1 to 30 parts to 0 parts. On this occasion(
C) If the amount of the component is less than 1 part based on the solid content of the polyurethane material, the resulting polyurethane material will have poor water dispersibility and may not be able to be water-dispersed, or even if it can be water-dispersed, it will be extremely unstable, which is not preferred. Furthermore, if the amount of component (C) is more than 30 parts per 100 parts of the polyurethane material, even if the amount is increased beyond this level, the effect of improving water dispersibility will not be noticeable and it will not only be uneconomical, but also The amount of component (C) used in the present invention is preferably 2 to 20 parts per 200 parts of solid content of the polyurethane material. is within the range of

In addition, in the present invention, it is also possible to add an organic solvent for the purpose of controlling the reaction system for obtaining the polyurethane material or reducing the viscosity. When using organic solvents, cost and ease of reaction control are important.

From the viewpoint of solubility of the polyurethane substance, aromatic hydrocarbons such as toluene and xylene, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, and acetic esters such as ethyl acetate and butyl acetate are preferably used. The monohydroxy compound-added polyurethane material thus obtained is then water-dispersed by adding water.

As a method for dispersing in water, water may be gradually added dropwise while stirring the polyurethane material to which a monohydroxy compound has been added, resulting in phase inversion emulsification, or polyurethane material to which a hydrophilic monohydroxy compound has been added to well-stirred water. The substance may be added gradually.

Usually, phase inversion emulsification is preferably used, in which water is gradually added dropwise to a polyurethane material to which a wood-philic monohydroxy compound has been added while stirring at high speed at a temperature of 60° C. or lower.

The aqueous polyurethane dispersion thus water-dispersed is preferably subjected to mechanical treatment to further atomize the polyurethane material. Examples of mechanical processing methods include methods using various homomixers such as a colloid mill, methods using a homogenizer, and methods using ultrasonic waves.

Furthermore, in the present invention, when dispersing a polyurethane material to which a monohydroxy compound has been added in water, it is recommended to use an organic solvent that is easily miscible with water in combination with the polyurethane material to which a monohydroxy compound has been added in advance to form a stable aqueous polyurethane material. This is a more preferred method for obtaining a dispersion. Such solvents include lower alcohols having 1 to 4 carbon atoms and various ethers such as hyethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, and propylene glycol monobutyl ether. and ketones such as acetone and methyl ethyl ketone.

The resulting aqueous polyurethane dispersion can be used as it is, but it is common to undergo an azeotropic removal process with water by heating and reducing pressure in order to remove the various organic solvents used together. .

EXAMPLES Next, Examples will be given to explain the present invention in more detail, but the present invention is not limited to these Examples. In the examples, all parts represent parts by weight.

Example 1 First, adipic acid-1,6 hexanediol-neopentyl glycol-polyester (01 value 58, molecular weight 1
935) to 9670 and polyoxyethylene monomethyl ether glycol (molecular formula CHI
(OCH3CH2). -OH) was added under reduced pressure to 1
After dehydration is carried out at 20-130°C, 183 parts of S-hexamethylene diisocyanate is added and reaction is carried out at 120°C for 2 hours while stirring the melt.

Next, the mixture was cooled to 60°C, 807 parts of methyl ethyl ketone was added, 45 parts of 1.4-butanediol and 0.4 parts of trimethylolpropane were added, and the mixture was stirred at 80°C for 3 hours to obtain a viscous transparent solution. . After diluting the resulting solution by adding 403 parts of isopropyl alcohol, 1,613 parts of water was added dropwise over 2 hours while keeping the temperature at 50°C.Methyl ethyl ketone and isopropyl alcohol were then distilled off under reduced pressure at 50°C, resulting in non-volatile properties. A milky white aqueous polyurethane dispersion with a content of 45.2% was obtained. This product formed a transparent, glossy, tough, elastic coating on a glass plate, and the coating had excellent water resistance, acid resistance, and alkali resistance. Furthermore, 20 parts of aluminum hydroxide powder was added as a filler to 100 parts of the obtained aqueous polyurethane dispersion and mixed and stirred using a homomixer, but the mixture was extremely stable.

For comparison, when aluminum hydroxide powder was added to a commercially available 7-ion polyurethane aqueous dispersion, lumpy aggregates were immediately formed.

Example 2 2150 parts of polyoxypropylene glycol with a molecular weight of 430 was added to the same apparatus as in Example 1, and the mixture was heated to 120 to 13 parts under reduced pressure.
Dehydration is carried out at 0°C, the mixture is cooled to 60°C, and 2240 parts of methyl ethyl ketone are added thereto, followed by 1210 parts of 4,4'-diphenylmethane diisocyanate. Hold at 80° C. for 2 hours, then give the general formula HO-(X)alY). -Ca
Add 235 parts of ethylene oxide-propylene oxide random polymer represented by H9 (molecular weight of polyoxyethylene moiety: 8000, polyoxyethylene/polyoxyalkylene = 80 (%)) and 10 parts of 4.4'-diphenylmethane diisocyanate at 80°C. After stirring for 3 hours, a viscous clear solution was obtained.

The obtained solution was mixed with 3167 parts of water for about 10 minutes while being maintained at 50°C, and then passed through a colloid mill for water dispersion.Methyl ethyl ketone was then distilled off under reduced pressure while being maintained at the same temperature, resulting in a non-volatile content of 55. A 4% milky aqueous dispersion was obtained. This product forms a transparent, glossy, and extremely tough film on the glass plate, and the film's water resistance and
Both acid resistance and alkali resistance were extremely excellent. or,
20 parts of aluminum hydroxide powder was added as a filler to 100 parts of the obtained aqueous polyurethane dispersion and mixed and stirred using a homomixer, but the mixture was extremely stable. For comparison, when aluminum hydroxide powder was added to a cationic polyurethane aqueous dispersion using commercially available N-methyl-ethanolamine as a chain extender, lump-like aggregates were immediately formed.

Example 3 Into the same apparatus as in Example 1, 500 parts of polyoxytetramethylene glycol with a molecular weight of 1000 and a lock polymer (polyoxyethylene portion molecules l 8
500, polyoxyethylene/polyoxyalkylene=
Add 100 parts of 75%) and 1.0 part of 1,1.1-) Liftirol Pro 2F, dehydrate at 120°C under reduced pressure, then add 111 parts of inphorone diisocyanate and react for 4 hours to form a viscous melt. is obtained. After adding 474 parts of isopropyl alcohol to the obtained melt, 593 parts of water were added dropwise at 50° C. over a period of 2 hours, and then the isopropyl alcohol was distilled off under reduced pressure at the same temperature. A milky white aqueous polyurethane dispersion with a non-volatile content of 42.4% was obtained. This product formed a transparent, glossy, elastic coating on a glass plate, and the coating had excellent water resistance, acid resistance, and alkali resistance. Furthermore, the obtained aqueous polyurethane dispersion had excellent compatibility with both anionic acrylic emulsions and cationic acrylic emulsions. For comparison, a commercially available aqueous anionic polyurethane dispersion was investigated and found to have good compatibility with anionic acrylic emulsion, but lumps were generated immediately when cationic acrylic emulsion was added.

Example 4 Adipic acid-isophthalic acid-1 was added to the same apparatus as in Example 1.
, 8 hexanediol polyester (08 value 58, molecular weight 1935) 98? part, 8O-(X)s-(Y). −
Ethylene oxide-butylene oxide random polymer (polyoxyethylene moiety) molecule H represented by CH3
Tolylene diisocyanate (2,4/2
．． 8 isomer ratio = 80/20) Add 171.5 parts and 80
The reaction was carried out at 0°C for 2 hours, then cooled to 40°C, 814 parts of acetone was added, 45.5 parts of N-methyljetanolamine was added, and 1,2-propylenediamine was gradually added dropwise. A thick clear solution was obtained. Add 60% ethylene glycol monobutyl ether to the resulting solution.
After diluting the mixture, add 1,970 ml of water to 1,970 ml of
The mixture was added dropwise over a period of 2 hours, and then the acetone was distilled off under reduced pressure at the same temperature to obtain a milky white aqueous polyurethane dispersion with a non-volatile content of 41.3%. This product formed a transparent, glossy, elastic coating on a glass plate, and the coating had excellent water resistance, acid resistance, and alkali resistance. Furthermore, the obtained aqueous polyurethane dispersion had extremely excellent stability when used in combination with various synthetic rubber latexes having ionic properties.

Comparative Example 1 In Example 1, polyoxyethylene monomethyl ether glycol (molecular formula HO-(CH2CH20).-C
H3) has a molecular weight of 20 instead of 4080.
A viscous transparent solution was synthesized in exactly the same manner except that No. 30 was used. After diluting the resulting solution by adding 403 parts of inpropyl alcohol, 13 parts of 1B water was added dropwise while keeping the solution at 50'C, but a white lump formed and it was not possible to disperse it in water.

Comparative Example 2 Ho-(x)s-(y)n~C instead of polyoxyethylene monomethyl ether glycol in Example 1
A viscous transparent solution was synthesized in exactly the same manner except that an ethylene oxide-propylene oxide block copolymer (polyoxyethylene moiety molecule fi 3100, polyoxyethylene/polyoxypropylene = 50%) that was aerated with H3 was used. . After diluting the resulting solution by adding 403 parts of isopropyl alcohol, water 16131 was added dropwise while keeping the solution at 50° C., but a white cake-like substance formed and water dispersion was not possible.

Comparative Example 3 Example 1. ! l-In a similar apparatus, 1001 parts of adipic acid-L, S hexanediol-polyester (08-valent 5B) was dehydrated at 120-130°C under reduced pressure, and then tolylene diisocyanate (2,4/2.8 isomer ratio) was dehydrated. = 80
/20) and reacted at 80°C for 2 hours. After diluting with 842 parts of acetone, 91 parts of N-methyljetanolamine was added and the reaction continued at 50°C for 3 hours. A thick clear solution was obtained. The obtained solution was gradually added to an aqueous solution prepared by dissolving 30 parts of vinegar in 2075 parts of water while stirring, to obtain an aqueous cationic polyurethane resin dispersion. This product forms a glossy transparent film on the glass plate, but the acid resistance of the film is extremely poor (3%11!). When immersed in acid, the film swelled significantly in a short period of time. Further, when 20 P) FR of aluminum hydroxide powder was added to the polyurethane aqueous dispersion, lump-like aggregates were formed.

[Effects of the Invention] As explained above, the aqueous polyurethane dispersion obtained by the method of the present invention is an aqueous dispersion of a high molecular weight polyurethane resin that does not substantially contain a nonionic emulsifier, and has good storage stability and It has excellent mechanical stability and compatibility with other resins, inorganic and organic pigments, fillers, etc., and the resulting film has excellent properties such as 1. water resistance and 1. chemical resistance, especially acid resistance and alkali resistance. Therefore, it can be applied to many applications for which conventional salt-type aqueous polyurethane dispersions are not suitable. i.e. coating of textiles, paper, leather, wood, metals, impregnation of fibers and textiles (e.g. texturing, anti-static, anti-wrinkle finishing, etc.), binders for fur,
Adhesives, adhesives, backing agents, hydrophobizing agents, elasticity in the construction industry, and prevention of crushing during transportation.
As a component for F (e.g. addition to concrete mixtures and asphalt mixtures), various paint vehicles,
It can be used for external paints and household aerosol paints. Furthermore, it can be used as a binder for coal powder, wood powder, glass fibers, asbestos, paper-like substances, plastic or rubber layers, ceramic materials, etc. Y! The product of the wood invention method is used as a softening agent in the production of elastic films, foils, and yarns.
It is also suitable as an auxiliary agent in textile printing and yarn industries, as an additive for synthetic resin dispersions, as a sizing agent, and as a leather finishing agent.

Claims (5)

[Claims] (1) (A) has at least two active hydrogen atoms capable of reacting with isocyanate groups in the molecule and has a molecular weight of 300
In a method for producing an aqueous polyurethane dispersion, which comprises reacting an active hydrogen-containing compound of ~20,000 with (B) an organic polyisocyanate compound to produce a polyurethane material, and then adding water, when producing the polyurethane material, ( C) The constituent units are oxyethylene units and at least one of oxypropylene units and oxybutylene units, and the terminals are -OH and -R (R represents an alkyl group having 1 to 20 carbon atoms). The monohydroxy compound represented by the formula has a total unit molecular weight of oxyethylene units of 2,500 to 15,000, and a total content of oxyethylene units of 60% of all oxyalkylenes.
1. A method for producing an aqueous polyurethane dispersion, which comprises reacting a compound in an amount of 1 to 30 parts by weight with respect to 100 parts by weight of solid content of the polyurethane material to be obtained. (2) A method for producing an aqueous polyurethane dispersion according to claim 1, which further comprises reacting (D) a chain extender having an active hydrogen atom capable of reacting with an isocyanate group during production of a polyurethane substance. . (3) A method for producing an aqueous polyurethane dispersion according to claim 1 or 2, in which an organic solvent that is easily miscible with water is coexisted when water is added to the polyurethane material to make it water-dispersed. (4) Claim 1, which includes a step of removing solvent and/or dehydration after adding water to the polyurethane material and making it water-dispersed.
A method for producing an aqueous polyurethane dispersion according to any one of items 1 to 3. (5) Claim 1, which includes a step of adding water to the polyurethane material to make it water-dispersed, or after performing a solvent removal and/or dehydration step, and then atomizing it by mechanical treatment.
5. A method for producing an aqueous polyurethane dispersion according to any one of Items 1 to 4.