Fine particle hydrotalcite, process for producing the same, resin composition thereof and suspension thereof

文档序号：1651891 发布日期：2019-12-24 浏览：44次中文

阅读说明：本技术 微粒水滑石、其制备方法、其树脂组合物及其悬浮液 (Fine particle hydrotalcite, process for producing the same, resin composition thereof and suspension thereof ) 是由森耕太郎宫田茂男于 2018-03-15 设计创作，主要内容包括：为了解决一次颗粒微细的水滑石(1)作为悬浮液长期贮存时一次颗粒发生集聚,(2)将悬浮液进行脱水、干燥而形成粉体时一次颗粒发生集聚的问题,本发明提供满足以下(A)～(C)的下述式(1)表示的水滑石。(M2+)1-X(M3+)X(OH)2(An-)X/n·mH2O(1)(式中M2+为2价金属,M3+为3价金属,An-为n价阴离子,n为1～6的整数,0.17≤x≤0.36,0≤m≤10。)(A)X射线衍射法测定的＜003＞方向的晶格畸变为3×10-3以下；(B)SEM法测定的一次颗粒的平均宽度为5nm以上200nm以下；(C)用下述式表示的单分散度为50％以上。单分散度(％)＝(SEM法测定的一次颗粒的平均宽度/动态光散射法测定的二次颗粒的平均宽度)×100。(In order to solve the problems that (1) primary particles are aggregated when the hydrotalcite having fine primary particles is stored as a suspension for a long period of time and (2) the primary particles are aggregated when the suspension is dehydrated and dried to form a powder, the present invention provides hydrotalcite having fine primary particles satisfying the following requirements(A) Hydrotalcite represented by the following formula (1) to (C). (M) 2+ ) 1‑X (M 3+ ) X (OH) 2 (A n‑ ) X/n ·mH 2 O (1) (in the formula, M 2+ Is a 2-valent metal, M 3+ Is a 3-valent metal, A n‑ Is n-valent anion, n is an integer of 1-6, x is more than or equal to 0.17 and less than or equal to 0.36, and m is more than or equal to 0 and less than or equal to 10. ) (A) lattice distortion in <003> direction measured by X-ray diffractometry is 3X 10 ‑3 The following; (B) the average width of the primary particles measured by SEM method is 5nm to 200 nm; (C) the monodispersity represented by the following formula is 50% or more. Monodispersity (%) × 100 (average width of primary particles measured by SEM method/average width of secondary particles measured by dynamic light scattering method).)

1. A hydrotalcite satisfying the following (A) to (C) and represented by the following formula (1),

(M²⁺)_1-X(M³⁺)_X(OH)₂(A^n-)_X/n·mH₂O (1)

wherein M is²⁺At least 1 or more kinds of 2-valent metals, M³⁺Is at least 1 or more of 3-valent metals, A^n-Is n-valent anion, n represents an integer of 1-6, x and m are respectively in the range of 0.17-0.36 and 0-10,

(A) lattice distortion in <003> direction of 3X 10 measured by X-ray diffraction method^-3The following;

(B) the average width of the primary particles measured by SEM method is 5nm to 200 nm;

monodispersity (%) × 100 (average width of primary particles measured by SEM method/average width of secondary particles measured by dynamic light scattering method).

2. The hydrotalcite according to claim 1, wherein (A) the lattice distortion in the <003> direction as determined by X-ray diffraction method is 2.5X 10^-3The following.

3. The hydrotalcite according to claim 1, wherein (B) the primary particles have an average width of 5nm to 150nm as measured by an SEM method.

4. The hydrotalcite according to claim 1, wherein (C) has a monodispersity of 80% or more.

5. Hydrotalcite according to claim 1, wherein M²⁺Is selected from more than 1 of Mg and Zn, M³⁺Is Al.

6. The hydrotalcite according to claim 1, wherein m is in the range of 0. ltoreq. m.ltoreq.0.05.

7. The hydrotalcite according to claim 1, having a BET specific surface area of 20 to 600m²/g。

8. The hydrotalcite according to claim 1, wherein the surface of the hydrotalcite is surface-treated with at least one member selected from the group consisting of anionic surfactants, cationic surfactants, phosphate ester-based treating agents, silane coupling agents, titanate coupling agents, aluminum coupling agents, silicone-based treating agents, silicic acid and sodium silicate.

9. A method for producing hydrotalcite, comprising the following 4 steps:

(1) a raw material preparation step of preparing a water-soluble complex metal salt aqueous solution and an alkali metal hydroxide aqueous solution, wherein the water-soluble complex metal salt aqueous solution contains a 2-valent metal salt, a 3-valent metal salt, and a 1-membered organic acid and/or organic acid salt that forms a complex with the 3-valent metal;

(2) a reaction step in which the aqueous solution of the water-soluble complex metal salt prepared in step (1) and an aqueous solution of an alkali metal hydroxide are continuously reacted at a reaction temperature of 0 to 60 ℃ and a reaction pH of 8.5 to 11.5 to obtain a suspension containing hydrotalcite;

(3) a washing step of dehydrating the hydrous talc-containing suspension obtained in the step (2), washing with water, and suspending the hydrous talc-containing suspension in water and/or an organic solvent;

(4) and (3) an aging step in which the suspension containing the washed hydrotalcite obtained in step (3) is continuously stirred at 0 to 100 ℃ for 1 to 60 hours.

10. The method for producing hydrotalcite according to claim 9, wherein in the raw material preparation step, the 1-membered organic acid and/or organic acid salt that forms a complex with the 3-valent metal is one or more selected from the group consisting of lactic acid, sodium lactate, acetic acid and sodium acetate.

11. The method for producing hydrotalcite according to claim 6, wherein the hydrotalcite according to claim 1 is dried at 100 to 350 ℃ for 1 to 24 hours.

12. A resin composition comprising 0.1 to 250 parts by weight of the hydrotalcite according to claim 1 per 100 parts by weight of the resin.

13. The resin composition according to claim 12, wherein the resin is a halogen-containing resin.

14. A molded article comprising the resin composition according to claim 12.

15. A suspension comprising the hydrotalcite according to claim 1 and a solvent selected from water and organic solvents, wherein the solvent is 0.1 to 300g/L in terms of solid content.

Technical Field

The present invention relates to a hydrotalcite having an X-ray diffraction structure different from that of conventional hydrotalcites, a small average width of primary particles, and few aggregates among the primary particles, a method for producing the same, a resin composition thereof, and a suspension thereof.

Background

Hydrotalcite may be synthesized by a coprecipitation method. Although primary particles of hydrotalcite obtained by the coprecipitation method are fine crystals having an average width of several tens of nm, the primary particles are strongly aggregated, and secondary particles are as large as several μm to several tens of μm.

Therefore, various developments have been made on hydrotalcite having an average width of primary particles as small as 200nm or less and having less aggregation between primary particles. However, in any of the methods, there is a problem that although the primary particles are dispersed immediately after the reaction, the primary particles gradually aggregate and settle when stored as a suspension for a long time. Further, there is a problem that primary particles are aggregated when the suspension is dehydrated and dried to form a powder.

In patent document 1, hydrotalcite having an average secondary particle size of 5nm to 100nm is obtained by wet pulverization after a coprecipitation reaction. In example 2, the just-in-advance is describedThe average secondary particle size of the suspension after wet grinding was 62nm, and the average secondary particle size of the suspension after standing for one day was 68 nm. However, the present inventors measured the average secondary particle size of the suspension after the reaction after leaving it for 10 days by an additional test, and the average secondary particle size was 600nm, and the primary particles were aggregated. There is also a problem that secondary particles are settled as the primary particles are aggregated. The suspension of example 2 immediately after the reaction was dehydrated, vacuum-dried and powdered to have an average secondary particle size of 4.5 μm and a BET specific surface area of 3.5m or less²The aggregation of primary particles was confirmed by SEM observation.

In patent document 2, it is said that hydrotalcite having an average secondary particle diameter of 1 to 100nm is obtained by using a microreactor as a reaction apparatus. However, when the inventors performed additional tests on example 1, the average secondary particle size in the suspension immediately after the reaction was about 30nm, but the average secondary particle size after standing for 10 days was 800 nm. In addition, agglomeration of primary particles also occurs. The problem of hydrotalcite settling accompanying such agglomeration of primary particles also arises. Further, when the suspension immediately after the reaction of example 1 was dehydrated and vacuum-dried, the obtained powder had an average secondary particle size of 3.8 μm and a BET specific surface area as low as 4.2m²(ii) in terms of/g. The agglomeration of primary particles was confirmed by SEM observation.

Patent document 3 describes that hydrotalcite having lactic acid inserted between layers is synthesized, and a colloidal hydrotalcite dispersion is formed by washing the hydrotalcite with water, suspending the hydrotalcite in water, aging the hydrotalcite, and removing the layers. In example 1, it is said that a translucent colloidal solution having hydrotalcite nanosheets as the dispersoid was obtained by using magnesium lactate, aluminum lactate, lactic acid and sodium hydroxide as the raw materials, washing the obtained reaction product with water, suspending the washed reaction product in water, and allowing the reaction product to stand for several days. However, in patent document 3, the reason why lactic acid is used as a raw material is to perform interlayer peeling of hydrotalcite, which is different from the improvement of primary particle dispersibility and the micronization which are the objects of the present application. An additional test was conducted on example 1, and the obtained colloidal solution was analyzed for dehydration and drying to obtain a powder, and the aggregation of primary particles was confirmed by SEM observation. Further, patent document 3 does not mention the particle diameter, lattice distortion, dispersibility, and suspension stability of hydrotalcite, and cannot be presumed to satisfy the conditions of hydrotalcite to be protected in the present application.

When hydrotalcite is used as a suspension, it is required that primary particles are not aggregated and precipitated even when they are stored for a long period of time, and that the hydrotalcite has suspension stability. Further, when hydrotalcite is used as a powder, it is also required to be nearly monodisperse without aggregation between primary particles. However, hydrotalcite satisfying these requirements has not been obtained by the existing methods.

Disclosure of Invention

Problems to be solved by the invention

The technical problem of the present invention is a problem of the prior art that occurs when the primary particle size of hydrotalcite is made small: (1) primary particles aggregate when the suspension is stored for a long period of time, and (2) primary particles aggregate when the suspension is dehydrated and dried to form a powder.

The present inventors have conducted earnest studies and, as a result, have found that the cause of these two problems is due to the lattice distortion of hydrotalcite crystallites. Hydrotalcite having a small primary particle diameter prepared by the conventional method has a large lattice distortion, and is used in an X-ray diffraction method<003>Lattice distortion in direction of at least 4 x 10^-3. If the lattice distortion is large, primary particles tend to aggregate when stored as a suspension for a long period of time or when formed into a powder. Accordingly, the present inventors have found that hydrotalcite having a small primary particle size and a small lattice distortion can be produced by carrying out a reaction under specific conditions and then aging, and have arrived at the present invention.

Means for solving the problems

The present invention provides hydrotalcite represented by the following formula (1) which satisfies the following (a) to (C) and can solve the above problems.

(M²⁺)_1-X(M³⁺)_X(OH)₂(A^n-)_X/n·mH₂O (1)

(wherein, M²⁺At least 1 or more kinds of 2-valent metals, M³⁺Is at least 1 or more of 3-valent metals, A^n-Is n-valent anion, n represents an integer of 1-6, x and m are respectively in the range of 0.17-0.36 and 0-10. )

(A) Lattice distortion in <003> direction of 3X 10 measured by X-ray diffraction method^-3The following;

(B) the average width of the primary particles measured by SEM method is 5nm to 200 nm;

Monodispersity (%) × 100 (average width of primary particles measured by SEM method/average width of secondary particles measured by dynamic light scattering method) ×

The method for producing hydrotalcite of the present invention comprises the following 4 steps.

(1) A raw material preparation step for preparing a water-soluble complex metal salt aqueous solution and an alkali metal hydroxide aqueous solution. Wherein the aqueous solution of the water-soluble complex metal salt contains a 2-valent metal salt, a 3-valent metal salt, and a 1-membered organic acid and/or organic acid salt that forms a complex with the 3-valent metal.

(2) And (2) a reaction step of continuously reacting the aqueous solution of the water-soluble complex metal salt prepared in the step (1) with an aqueous solution of an alkali metal hydroxide at a reaction temperature of 0 to 60 ℃ and a reaction pH of 8.5 to 11.5 to obtain a suspension containing hydrotalcite.

(3) And (3) a washing step of dehydrating the hydrous talc suspension obtained in the step (2), washing with water, and suspending the hydrous talc suspension in water and/or an organic solvent.

(4) And (3) an aging step of continuously stirring the cleaned hydrotalcite-containing suspension obtained in step (3) at 0 to 100 ℃ for 1 to 60 hours.

A1-membered organic acid and/or organic acid salt which forms a complex with a 3-valent metal is added as a complexing agent during the reaction to raise the precipitation pH of the hydroxide which is a 3-valent metal to approach the precipitation pH of a 2-valent metal, thereby enabling to reduce lattice distortion of hydrotalcite and prevent aggregation of primary particles. In addition, the complexing agent also has an effect of inhibiting crystal growth of primary particles of the hydrotalcite during the reaction due to steric effects of molecules of the complexing agent. In the aging step, the hydrotalcite-containing suspension after the reaction and water washing is continuously stirred at 0-100 ℃ for 1-60 hours, so that the dispersibility of the primary particles can be further improved.

ADVANTAGEOUS EFFECTS OF INVENTION

The hydrotalcite of the present invention can be used for various applications such as a heat stabilizer for vinyl chloride resins, a neutralizer for polyolefin polymerization catalyst residues, an acid acceptor for halogen-containing rubbers, and a heat insulating agent for agricultural films. In particular, the hydrotalcite-containing suspension may be suitably used as a liquid antacid or a heat stabilizer. The hydrotalcite of the present invention has a significantly improved anion exchange capacity as compared with conventional hydrotalcite products, and therefore, it can be used as a stabilizer, a neutralizer and an acid acceptor which are superior to conventional hydrotalcite products in the same amount of incorporation, and can exhibit the same performance as conventional hydrotalcite products in a smaller amount of incorporation. In addition, when compounded into a resin, the resin has higher transparency than the conventional hydrotalcite of the same amount.

Drawings

Fig. 1 is a schematic diagram illustrating the width of primary particles of hydrotalcite of the present invention.

Fig. 2 is a schematic diagram illustrating the width of the secondary particles of the hydrotalcite of the present invention.

Fig. 3 is an SEM photograph of 10,000 times of hydrotalcite of sample 4 of example 4.

Fig. 4 is an SEM photograph of 100,000 times of hydrotalcite of sample 4 of example 4.

Fig. 5 is an SEM photograph of 10,000 times of hydrotalcite of sample 15 of comparative example 2.

Fig. 6 is an SEM photograph of 100,000 times of hydrotalcite of sample 15 of comparative example 2.

Fig. 7 is an SEM photograph of 10,000 times of hydrotalcite of sample 19 of comparative example 6.

Fig. 8 is an SEM photograph of 100,000 times of hydrotalcite of sample 19 of comparative example 6.

Detailed description of the invention

The present invention will be specifically described below.

< hydrotalcite >

The chemical formula, the metal type, the range of x (the presence ratio of a 2-valent metal to a 3-valent metal), the range of m, the type of interlayer anion, the lattice distortion in the <003> direction, the average width of primary particles, the monodispersity, the BET specific surface area, and the surface treatment of the hydrotalcite of the present invention are as follows.

(chemical formula)

The hydrotalcite of the present invention is represented by the following formula (1).

(M²⁺)_1-X(M³⁺)_X(OH)₂(A^n-)_X/n·mH₂O(1)

(kind of Metal)

In the hydrotalcite represented by the formula (1), M²⁺At least 1 or more kinds of 2-valent metals, M³⁺Is at least 1 or more of 3-valent metals. The preferred 2-valent metal is one or more of Mg and Zn, and the preferred 3-valent metal is Al. This is because it is highly safe to living bodies, and the particles are white and have a wide range of applications.

(range of x)

In the hydrotalcite represented by the formula (1), x is in the range of 0.17. ltoreq. x.ltoreq.0.36, preferably 0.19. ltoreq. x.ltoreq.0.34. If x exceeds 0.36, boehmite is by-produced, whereas if x is less than 0.17, magnesium hydroxide is by-produced, both of which cause a decrease in transparency when incorporated into a resin.

(range of m)

In the hydrotalcite represented by the formula (1), m is in the range of 0. ltoreq. m.ltoreq.10, preferably 0. ltoreq. m.ltoreq.6.

As the temperature of the hydrotalcite increases, crystal water removal occurs around about 180 ℃ and 230 ℃. Therefore, when the hydrotalcite is blended with a synthetic resin and used, when the temperature of the treatment such as kneading or crosslinking is 200 ℃ or higher, m is preferably 0. ltoreq. m.ltoreq.0.05. This is because if m is within this range, problems such as foaming of the resin and crazing due to crystal water removal can be prevented.

(kind of interlayer anion)

In the hydrotalcite represented by the formula (1), A^n-Is an anion of n valence, n represents an integer of 1 to 6, preferably A^n-Is selected from CO₃ ^2-And ClO₄ ^-More than one of them.

(< 003> directional lattice distortion)

In the hydrotalcite of the present invention, the lattice distortion in the <003> direction as measured by X-ray diffraction method is 3X 10^-3Hereinafter, it is preferably 2.5X 10^-3Hereinafter, more preferably 2 × 10^-3The following. If the <003> direction lattice distortion is larger than 3X 10^-3When the particles are formed into a powder, and when the particles are stored as a suspension for a long period of time, the primary particles tend to aggregate.

(definition of Primary particle)

Primary particles are particles with sharp boundaries that cannot be further geometrically segmented. FIG. 1 is a view for explaining the width (W) of primary particles used in the present invention₁) Schematic representation of (a). As shown in FIG. 1, the width W of the primary particle is defined₁. That is, the major axis of the particle when the primary particle is regarded as a hexagonal plate is "the width W of the primary particle₁”。

(definition of Secondary particle)

The secondary particles are aggregated particles formed by aggregating a plurality of primary particles. FIG. 2 is a view for explaining secondary particles used in the present invention and a secondary particle width (W)₂) Schematic representation of (a). As shown in fig. 2, a width W of the secondary particle is defined₂. That is, the diameter of the sphere when considering that the secondary particles are enclosed into a sphere is "the width W of the secondary particles₂”。

(average Width of Primary particle)

In the hydrotalcite of the present invention, the average width of the primary particles measured by SEM is 5nm to 200nm, preferably 5nm to 150nm, more preferably 5nm to 100nm, even more preferably 5nm to 80nm, even more preferably 5nm to 60nm, and most preferably 5nm to 50 nm. The average width of the primary particles is determined by the arithmetic mean of the measured widths of any 100 crystals on the SEM photograph in the SEM method. In principle, the width of the primary particles cannot be determined by laser diffraction. Therefore, visual confirmation was performed by SEM.

(Monodispersity)

The hydrotalcite of the present invention has a monodispersity represented by the following formula of 50% or more, preferably 80% or more. The width of the secondary particles was measured by dynamic light scattering. Since it is difficult to accurately determine the width of the secondary particles for the SEM method.

Monodispersity (%) × 100 (average width of primary particles measured by SEM method/average width of secondary particles measured by dynamic light scattering method) ×

(BET method specific surface area)

The hydrotalcite of the invention has a BET specific surface area of 20 to 600m²Preferably 30 to 500 m/g²A concentration of 40 to 400 m/g is more preferable²(ii) in terms of/g. If the BET specific surface area is less than 20m²In terms of/g, the primary particles in the form of powder are not sufficiently dispersed. If it exceeds 600m²In terms of the ratio of the amount of the polymer to the amount of the polymer, the volume of the powder is large, and the workability in kneading the powder with a synthetic resin is deteriorated.

(surface treatment)

The hydrotalcite of the present invention is preferably surface-treated for improving dispersibility in a resin. Examples of the surface treatment agent include, but are not limited to, anionic surfactants, cationic surfactants, phosphate ester treatment agents, silane coupling agents, titanate coupling agents, aluminum coupling agents, silicone treatment agents, silicic acid, and sodium silicate. Particularly preferred surface treating agents are one or more selected from oleic acid, stearic acid, caprylic acid and caprylic acid. The amount of the surface treatment agent is 0.01 to 20% by weight, preferably 0.1 to 15% by weight, based on the weight of the hydrotalcite.

< resin composition >

The resin composition of the present invention contains the hydrotalcite of the present invention in an amount of 0.1 to 250 parts by weight based on 100 parts by weight of the resin. The amount of hydrotalcite is more preferably 1 to 200 parts by weight per 100 parts by weight of the resin.

The method for mixing and kneading the resin and the hydrotalcite of the present invention is not particularly limited, but a method capable of uniformly mixing both is preferable. For example, the mixing and kneading may be carried out by a single-screw or twin-screw extruder, a roll, a Banbury mixer, or the like. The molding method is not particularly limited, and any known molding method can be used depending on the types of the resin and the rubber, the type of the desired molded article, and the like. For example, injection molding, extrusion molding, blow molding, press molding, rotational molding, calender molding, sheet molding, transfer molding, lamination molding, vacuum molding, and the like.

The resin used in the present invention is a resin and/or a rubber, and examples thereof include polyvinyl chloride, polyvinyl bromide, polyvinyl fluoride, polyvinylidene chloride, chlorinated polyethylene, chlorinated polypropylene, brominated polyethylene, chlorinated rubber, vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-isobutylene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-styrene-acrylonitrile copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-chlorinated propylene copolymer, vinyl chloride-vinylidene chloride-vinyl acetate terpolymer, vinyl chloride-maleate copolymer, vinyl chloride-methacrylic acid copolymer, vinyl chloride-methacrylate copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-methacrylic acid copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl, Vinyl chloride-acrylonitrile copolymers, and internally plasticized polyvinyl chloride. Further, thermoplastic resins such as polyethylene, copolymers of ethylene and other α -olefins, copolymers of ethylene and vinyl acetate, copolymers of ethylene and acrylic acid ether, copolymers of ethylene and methyl acrylate, polypropylene, copolymers of propylene and other α -olefins, polybutene-1, poly-4-methylpentene-1, polystyrene, copolymers of styrene and acrylonitrile, copolymers of ethylene and propylene diene rubbers, copolymers of ethylene and butadiene, polyvinyl acetate, polylactic acid, polyvinyl alcohol, polyacrylates, polymethacrylates, polyurethane, polyester, polyether, polyamide, ABS, polycarbonate, and polyphenylene sulfide can be cited. Further, thermosetting resins such as phenol resins, melamine resins, epoxy resins, unsaturated polyester resins, and alkyd resins are also included. Further, EPDM, SBR, NBR, butyl rubber, chloroprene rubber, isoprene rubber, chlorosulfonated polyethylene rubber, silicone rubber, fluororubber, chlorobutyl rubber, bromobutyl rubber, epichlorohydrin rubber and the like are also included

In addition to the hydrotalcite, other additives such as a reinforcing agent such as an antioxidant and talc, a delustering agent such as an ultraviolet absorber, a lubricant and microsilica, a pigment such as carbon black, a flame retardant such as a bromine-based flame retardant and a phosphate-based flame retardant may be appropriately selected and blended in the resin composition of the present invention. Further, a flame retardant auxiliary such as zinc stannate, alkali metal stannate, or carbon powder, or a filler such as calcium carbonate can be appropriately selected and blended. The preferred compounding amounts of these additives are, relative to 100 parts by weight of the resin: 0.01-5 parts by weight of antioxidant, 0.1-50 parts by weight of reinforcing agent, 0.01-5 parts by weight of ultraviolet absorbent, 0.1-5 parts by weight of lubricant, 0.01-5 parts by weight of flatting agent, 0.01-5 parts by weight of pigment, 0.1-50 parts by weight of flame retardant, 0.01-10 parts by weight of flame retardant auxiliary agent and 1-50 parts by weight of filler.

< shaped body >

The present invention includes a molded article formed of the resin composition.

< suspension >

The solvent of the suspension is water and/or an organic solvent, and the concentration of the hydrotalcite is 0.1-300 g/L. The concentration of the hydrotalcite is preferably 0.5 to 250g/L, and more preferably 1 to 200 g/L.

Examples of the organic solvent used in the present invention include benzene, toluene, xylene, n-hexane, isohexane, n-heptane, cyclohexane, methylcyclohexane, ethylcyclohexane, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, octanol, monoethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, ethyl acetate, butyl acetoacetate, amyl acetate, methyl acetate, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, isophorone, diacetone alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, isopropyl ether, methylene chloride, trichloroethylene, tetrachloroethylene, tetrahydrofuran, N, N-dimethylformamide, ethyl acetate, butyl acetate, amyl acetate, methyl acetate, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, isophorone, dimethyl sulfoxide, N-methyl-2-pyrrolidone, γ -butyrolactone, dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, dibutyl phthalate, dioctyl adipate, diisononyl adipate, trioctyl trimellitate, tricresyl phosphate, tributyl acetyl citrate, epoxidized soybean oil, epoxidized linseed oil, sebacate, azelate, maleate, benzoate, and the like, but is not limited thereto.

< method for producing hydrotalcite >

The method for producing hydrotalcite of the present invention comprises the following 4 steps.

(1) A raw material preparation step for preparing a water-soluble complex metal salt aqueous solution and an alkali metal hydroxide aqueous solution. Wherein the aqueous solution of the water-soluble complex metal salt comprises a 2-valent metal salt, a 3-valent metal salt, and a 1-membered organic acid and/or organic acid salt that forms a complex with the 3-valent metal.

(3) And (3) a washing step of dehydrating the hydrous talc suspension obtained in the step (2), washing with water, and suspending the hydrous talc suspension in water and/or an organic solvent.

(4) And (3) an aging step of continuously stirring the cleaned hydrotalcite-containing suspension obtained in step (3) at 0 to 100 ℃ for 1 to 60 hours.

(raw Material preparation Process)

The hydrotalcite of the present invention is prepared from a 2-valent metal salt, a 3-valent metal salt, a 1-membered organic acid and/or organic acid salt that forms a complex with the 3-valent metal, and an alkali metal hydroxide salt. Examples of the 2-valent metal salt include water-soluble 2-valent metal salts such as magnesium chloride, magnesium bromide, magnesium nitrate, magnesium acetate, zinc chloride, zinc bromide, zinc nitrate, and zinc acetate, but are not limited thereto. To prevent agglomeration of the primary particles, it is preferable to use a 2-valent metal salt containing a 1-valent anion. It is also possible to use 2 or more kinds of the 2-valent metal salts in combination. Preferably, magnesium chloride and/or zinc chloride are used. As the 3-valent metal salt, water-soluble 3-valent metal salts such as aluminum chloride, aluminum bromide, aluminum nitrate, and aluminum acetate can be cited, but not limited thereto. To prevent agglomeration of the primary particles, it is preferable to use a 3-valent metal salt containing a 1-valent anion. Combinations of 2 or more of the 3-valent metal salts may also be used. Aluminum chloride is preferably used.

Generally, the precipitation pH of the 3-valent metal ion as a hydroxide is lower than the precipitation pH of the 2-valent metal. Therefore, even if the pH value during the reaction is kept constant by the pH adjuster, the 3-valent ions first form hydroxides and precipitate. Due to the difference in the precipitation pH values of the 2-valent metal and the 3-valent metal, lattice distortion occurs, and primary particles of hydrotalcite agglomerate.

Therefore, by using a 1-membered organic acid and/or organic acid salt as a complexing agent to form a complex with a metal having a valence of 3, the precipitation pH of the hydroxide of the metal ion having a valence of 3 is increased to be close to the precipitation pH of the metal ion having a valence of 2, and thus hydrotalcite having less lattice distortion can be obtained. The complexing agent also has the effect of inhibiting the primary particle crystal growth of the hydrotalcite due to the steric effect of the molecules of the complexing agent. Examples of the 1-membered organic acid and/or organic acid salt that forms a complex with the 3-valent metal include, but are not limited to, lactic acid, sodium lactate, formic acid, sodium formate, acetic acid, sodium acetate, propionic acid, and sodium propionate. It is also possible to combine 2 or more organic acids and organic acid salts. Preferably, lactic acid, sodium lactate, acetic acid and sodium acetate are used. Examples of the alkali metal hydroxide salt include, but are not limited to, sodium hydroxide and potassium hydroxide.

Dissolving 2-valent metal salt, 3-valent metal salt and 1-membered organic acid and/or organic acid salt forming complex with 3-valent metalDissolving in water solvent to obtain water-soluble composite metal salt aqueous solution. The concentration of the 2-valent metal in the water-soluble composite metal salt aqueous solution is 0.01 to 2mol/L, preferably 0.1 to 1.5 mol/L. The concentration of the 3-valent metal is 0.01 to 2mol/L, preferably 0.1 to 1.5 mol/L. The concentration of the alkali metal hydroxide is 0.01 to 4mol/L, preferably 0.1 to 2 mol/L. The ratio of the 2-valent metal to the 3-valent metal is 1.78-M²⁺/M³⁺4.88, preferably 1.94M²⁺/M³⁺Less than or equal to 4.26. The amount of the 1-membered organic acid and/or organic acid salt to be added to form a complex with the 3-valent metal is 0.1 to 2.2 equivalents, preferably 0.3 to 2 equivalents, relative to the 3-valent metal. If the amount is less than 0.1 equivalent, the primary particles of hydrotalcite may be 200nm or more, which is not preferable. If it is more than 2.2 equivalents, anions derived from the complexing agent may enter between the layers of the hydrotalcite, leading to gelation of the suspension by swelling, and therefore, it is not preferable.

(reaction procedure)

The hydrotalcite of the present invention may be prepared by a continuous reaction. The ion concentration and pH value in the solution can be kept uniform as compared with the batch reaction, and hence hydrotalcite having less lattice distortion can be produced, and the production efficiency is high as compared with the batch reaction.

The concentration during the reaction is 0.1 to 300g/L, preferably 0.5 to 250g/L, and more preferably 1 to 200g/L in terms of hydrotalcite. When the concentration is less than 0.1g/L in the reaction, the productivity is low, and when it is more than 300g/L, primary particles are aggregated, which is not preferable. The reaction temperature is 0 to 60 ℃, preferably 10 to 50 ℃, and more preferably 20 to 40 ℃. The temperature at the time of the reaction is not preferably lower than 0 ℃ because the suspension is frozen, and not preferably higher than 60 ℃ because the primary particle size is not less than 200 nm. The pH value during the reaction is 8.5 to 11.5, preferably 8.8 to 11.0, and more preferably 9.1 to 10.5. When the pH value during the reaction is less than 8.5, the crystal lattice distortion of hydrotalcite becomes large and the monodispersity decreases, which is not preferable, and when the pH value is more than 11.5, the primary particle size of aged hydrotalcite becomes 200nm or more, which is not preferable.

(cleaning Process)

The suspension containing hydrotalcite prepared in the reaction step is dehydrated, washed with deionized water in an amount of 20 to 30 times the weight of hydrotalcite, and resuspended in water and/or an organic solvent. After this step, salts such as sodium are removed, and primary particles can be prevented from being aggregated in the aging step.

In the washing process, after dehydration and before water washing, ion exchange may be performed with any anion. There are two ion exchange methods. The first is a method in which a suspension containing hydrotalcite is dehydrated after the reaction to form a cake, dispersed in water and/or alcohol, and an anion-containing aqueous solution is added with continuous stirring. In this case, the anion equivalent is 1 to 5 equivalents, more preferably 1.5 to 3 equivalents, relative to the hydrotalcite. The temperature for continuous stirring is preferably 30 to 90 ℃, and more preferably 50 to 80 ℃. The concentration of hydrotalcite is preferably 0.1 to 300g/L, more preferably 0.5 to 250g/L, and further preferably 1 to 200g/L in terms of hydrotalcite.

The second ion exchange method is a method in which a hydrotalcite-containing suspension after reaction is dehydrated to form a cake, and then an aqueous solution containing anions is directly added thereto. In this case, the amount of the anion added is 1 to 5 equivalents, preferably 1.5 to 3 equivalents, relative to the hydrotalcite.

(aging Process)

The suspension of hydrotalcite prepared by the washing step is continuously stirred at 0 to 100 ℃ for 1 to 60 hours. This step reduces the aggregation of the primary particles, and a suspension having the primary particles dispersed sufficiently can be obtained. If the aging time is less than 1 hour, the time for alleviating the aggregation of primary particles is insufficient. The aggregation state did not change even if the aging time exceeded 60 hours, and thus it was not meaningful. The preferred aging time is 2 to 30 hours, more preferably 4 to 24 hours. If the aging temperature is higher than 100 ℃, the primary particles may exceed 200nm, and thus it is not preferable. If the aging temperature is less than 0 ℃, the suspension freezes, and therefore, this is not preferable. The preferred aging temperature is 20-90 deg.C, more preferably 40-80 deg.C. The concentration during aging is 0.1 to 300g/L, preferably 0.5 to 250g/L, and more preferably 1 to 200g/L in terms of hydrotalcite. A concentration lower than 0.1g/L at the time of aging is not preferable because productivity is low and primary particles are aggregated at a concentration higher than 300 g/L.

(surface treatment Process)

After the aging step, the hydrotalcite particles are surface-treated to prevent the primary particles from aggregating in the resin during kneading and dispersing in the suspension or when added to the resin. The surface treatment may be performed by a wet method or a dry method. From the viewpoint of uniformity of treatment, a wet method is suitably employed. The temperature of the suspension after the aging step is adjusted, and a surface treatment agent dissolved with stirring is added. The temperature at the time of surface treatment is suitably adjusted to a temperature at which the surface treatment agent dissolves.

The surface treatment agent may be selected from at least one of an anionic surfactant, a cationic surfactant, a phosphate ester treatment agent, a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, a silicone treatment agent, and sodium silicate. Particularly preferred surface treating agents are one or more selected from oleic acid, stearic acid, caprylic acid and caprylic acid. The amount of the surface treatment agent is 0.01 to 20% by weight, preferably 0.1 to 15% by weight, based on the weight of the hydrotalcite.

(suspension/drying step)

And (3) dehydrating the suspension subjected to surface treatment, and washing with deionized water which is 20-30 times the weight of the solid.

When the hydrotalcite is suspended, the hydrotalcite after washing with water is suspended in water and/or an organic solvent. The concentration of the hydrotalcite is 0.1-300 g/L, preferably 0.5-250 g/L, and more preferably 1-200 g/L. The suspension method is not particularly limited as long as the particles can be uniformly suspended in the solvent. Examples of the organic solvent include benzene, toluene, xylene, n-hexane, isohexane, n-heptane, cyclohexane, methylcyclohexane, ethylcyclohexane, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, octanol, monoethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, ethyl acetate, butyl acetoacetate, amyl acetate, methyl acetate, propylene glycol monomethyl ether acetate, methyl ethyl ketone, acetone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, isophorone, diacetone alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, isopropyl ether, methylene chloride, trichloroethylene, tetrachloroethylene, tetrahydrofuran, N, N-dimethylformamide, and mixtures thereof, Dimethyl sulfoxide, N-methyl-2-pyrrolidone, γ -butyrolactone, dioctyl phthalate, diisononyl phthalate, diisodecyl phthalate, dibutyl phthalate, dioctyl adipate, diisononyl adipate, trioctyl trimellitate, tricresyl phosphate, tributyl acetyl citrate, epoxidized soybean oil, epoxidized linseed oil, sebacate, azelate, maleate, benzoate, and the like, but is not limited thereto.

The hydrotalcite of the present invention is obtained by washing hydrotalcite powder with water and then drying the washed hydrotalcite powder. The drying method may be hot air drying, vacuum drying, or the like, and is not particularly limited. In order to prevent agglomeration between primary particles when water is used as a medium, vacuum drying is preferably used.

In the hydrotalcite of the present invention, when m is in the range of 0. ltoreq. m.ltoreq.0.05, the drying temperature is preferably 120 to 350 ℃ and the holding time is preferably 1 to 24 hours. By this treatment, the crystal water of the hydrotalcite can be removed so that m is in the range of 0. ltoreq. m.ltoreq.0.05. The preferable drying temperature is 130 to 340 ℃, and more preferably 140 to 330 ℃. The preferable drying time is 1.5 to 22 hours, and more preferably 2 to 20 hours.

The present invention will be described in detail with reference to the following examples, but the present invention is not limited to these examples. In the examples, various physical properties were measured by the following methods.

(a) <003> directional lattice distortion

The crystal grain size (g) is obtained from the reciprocal of the intercept by plotting (sin θ/λ) on the horizontal axis and (β cos θ/λ) on the vertical axis according to the following relational expressions, and the lattice distortion (η) is obtained by multiplying the slope by (1/2).

(βcosθ/λ)＝(1/g)+2η×(sinθ/λ)

(wherein. lambda. denotes the wavelength of the X-ray used, and for Cu-Ka lineTheta denotes the bragg angle and beta denotes the true half-value width (unit: radian). )

The β is determined by the following method.

Diffraction curves of the (003) plane and the (006) plane were measured using an X-ray diffractometer (Empyrean, manufactured by Panalytical) using Cu — K α rays generated under conditions of 45KV and 40mA as an X-ray source. The measurement conditions were: the goniometer speed was 10 °/min, and the slit width was measured for the (003) plane under the conditions of 1 ° -0.3mm-1 ° in order for the entrance slit, the receiving slit, and the scattering slit, and the slit width was measured for the (006) plane under the conditions of 2 ° -0.3mm-2 ° in order for the entrance slit, the receiving slit, and the scattering slit. For the obtained curve, the width (B) from the background to the height (1/2) of the diffraction peak was measured₀). From K_α1、K_α2The relative relationship between the slit width (δ) and 2 θ of (c) is read, and the δ values of 2 θ corresponding to the (003) plane and the (006) plane are read. Then, based on the above B₀And the value of δ, from (δ/B)₀) And (B/B)₀) The relationship between them is determined as B. Subsequently, for high purity silicon (purity: 99.999%), each diffraction curve was measured at a slit width (1/2) ° -0.3mm- (1/2) ° to find a half-value width (b). This is plotted against 2 θ, and a graph showing the relationship between b and 2 θ is created. (b/β) is obtained from b corresponding to 2 θ of (003) plane and (006) plane. β is obtained from the relationship between (B/B) and (β/B).

(b) Average width of primary particles

After the sample was added to ethanol and subjected to ultrasonic treatment for 5 minutes, the width of primary particles of any 100 crystals was measured using a Scanning Electron Microscope (SEM) (JSM-7600F, manufactured by japan electronics), and the arithmetic average thereof was taken as the average width of the primary particles.

After the sample was added to ethanol and subjected to ultrasonic treatment for 5 minutes, the particle size distribution was measured using a dynamic scatterometry particle sizer (ELSZ-2, available as Otsuka Denshi), and the number average diameter thereof was taken as the average width of the secondary particles.

(d) Degree of monodispersity

Calculated from the values of (b) and (c) based on the following formula.

Monodispersity (%) × 100 (average width of primary particles measured by SEM method/average width of secondary particles measured by dynamic light scattering method) ×

(e) BET specific surface area

The specific surface area of the dried sample was measured by a gas adsorption method using a specific surface area measuring apparatus (NOVA2000, manufactured by Yuasa Ionics).

(f) Quantification of chemical composition

After heating and dissolving the sample in nitric acid, Mg, Zn, and Al were quantified by chelate titration, and Cl was quantified by Volhard titration. AGK formula CO was used in accordance with JIS.R.9101₂Simple precise quantitative device for CO₃Quantification was performed. Interlaminar water was calculated by weight loss using TG-DTA.

(g) Quantification of surface treatment amount

The oleic and stearic acid treatment of the samples was quantified by ether extraction.

(h) Thermal stability test of vinyl chloride resin

The samples were compounded into polyvinyl chloride resin in the following proportions to evaluate thermal stability.

Polyvinyl chloride (polymerization degree 1300): 100 portions of

DOP: 50 portions of

Sample preparation: 1.6 parts of

Zinc stearate: 0.4 portion of

The mixture was kneaded at 170 ℃ for 5 minutes using an 8-inch roll to prepare a test roll sheet having a thickness of 0.7 mm. The obtained rolled sheet was formed into a test piece having a length and a width of 4cm, placed on a stainless steel plate, and subjected to a thermal stability test at 190 ℃ in a Geer furnace at an opening of 60%. The thermal stability was evaluated using the time (minutes) before the occurrence of blackening or black spots. The longer the time before the black spot appears, the better the thermal stability.

(i) Transparency test of vinyl chloride resin

The rolled sheet prepared in (h) was cut into a length and width of 4cm, superimposed in 3 pieces, put into a mold having a thickness of 2mm, sandwiched from above and below with stainless steel plates, and pressed with a press at 200 ℃ and 100MPa for 10 minutes to prepare a test piece. The haze (haze) of the prepared test piece was measured by a haze meter (automatic haze meter TC-H3DP, tokyo electric color) in accordance with jis.k.7136, and the transparency was evaluated. The lower the haze, the better the transparency.

(j) Suspension stability test

10g of the surface-treated and water-washed hydrotalcite as a solid was added to 1L of isopropyl alcohol, and stirred with a homogenizer at 6000rpm for 20 minutes to prepare a suspension. The suspension was transferred to a 1L settling tube and left to stand in this state for 10 days. Samples were taken immediately after suspension, 1 day later, 10 days later, and the average width and sedimentation state of the secondary particles were evaluated in each case. With respect to the average width of the secondary particles, the suspension was subjected to ultrasonic treatment for 5 minutes, and then the particle size distribution was measured using a dynamic light scattering particle size analyzer (ELSZ-2, manufactured by tsukamur electronics). The number average diameter is defined as the average width of the secondary particles. Further, the sedimentation state was visually observed after 1 day and 10 days, and when the water layer and the layer containing particles were completely separated, it was evaluated as "x", and when no layer separation was observed, it was evaluated as "o".

Example 1

(raw Material preparation Process)

Magnesium chloride hexahydrate (and optical pure chemical) and aluminum chloride hexahydrate (and optical pure chemical) are dissolved in deionized water to obtain an aqueous solution with 0.2mol/L magnesium and 0.1mol/L aluminum. To this aqueous solution was added 1.75 equivalents of sodium lactate (kishida chemical) relative to aluminum to form an aqueous water-soluble complex metal salt solution. On the other hand, sodium hydroxide (Wako pure chemical industries, Ltd.) was dissolved in deionized water to a concentration of 0.8mol/L to obtain an aqueous alkali metal hydroxide solution.

(reaction procedure)

The flow rates of the aqueous solution of the water-soluble composite metal salt and the aqueous solution of the alkali metal hydroxide were set to 120mL/min and 95mL/min, respectively, and the aqueous solution were poured into a cylindrical reaction tank having an overflow capacity of 215mL to carry out continuous reaction. Collecting the suspension overflowing from the reaction tank as overflow, and adjusting the flow of the alkali metal hydroxide solution to make the pH value 9.3-9.6. Also, the temperatures of the raw materials and the reaction tank were adjusted so that the reaction temperature was 25 ℃ during the reaction. A propeller having a diameter of 2.5cm was used for the reaction, and the stirring was carried out at 1000 rpm.

(cleaning Process)

The suspension was dewatered by suction filtration using a round Nutsche suction filter and suction flask to form a filter cake. Subsequently, an aqueous solution of sodium carbonate was injected in an amount of 1.5 equivalents to the aluminum of the hydrotalcite contained in the cake, and ion exchange was performed. Next, the ion-exchanged cake was washed with water using deionized water 30 times by mass as much as hydrotalcite in order to remove by-products such as salts and impurities such as sodium carbonate remaining.

(aging Process)

The washed filter cake was resuspended in deionized water. Resuspension was performed using a homogenizer at 4000rpm for 20 minutes. Deionized water was added to the resuspended suspension to adjust the concentration to 50 g/L. The suspension after the concentration adjustment was kept at 60 ℃ in a constant temperature bath and aged for 24 hours.

(surface treatment Process)

To oleic acid (Wako pure chemical industries, Ltd.), 1mol/L of an aqueous solution of sodium hydroxide (Wako pure chemical industries, Ltd.) was added in an amount of 1 equivalent to the oleic acid to obtain an aqueous solution of sodium oleate. The concentration of the aqueous solution of sodium oleate was adjusted with deionized water so that the oleic acid concentration was 5 g/L.

The concentration of the aged suspension was adjusted to 10g/L, and then the temperature was adjusted to 60 ℃ using a thermostatic bath, and an aqueous solution of sodium oleate was injected in an amount of 10 wt%. After the injection of the aqueous sodium oleate solution, stirring was continued at 60 ℃ for 30 minutes.

(drying Process)

After the surface treatment, the suspension cooled to room temperature was dehydrated using a round Nutsche suction filter and a suction flask to obtain a cake. In order to remove impurities such as residual salts contained in the cake after the surface treatment, deionized water was used in an amount 20 times the amount of the solid content of the reaction product to perform water washing.

The filter cake after washing was placed in a stainless steel drum, and the vacuum degree was maintained at 30cmHg by a vacuum pump at 40 ℃ in a vacuum drier, and the filter cake was left for one night to obtain sample 1. The experimental conditions of example 1 are shown in table 1, and the chemical composition, the crystal distortion in the <003> direction, the average width of the primary particles, the average width of the secondary particles, the monodispersity, the BET specific surface area, and the surface treatment amount thereof are shown in table 2.

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Fine particle hydrotalcite, process for producing the same, resin composition thereof and suspension thereof

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