JP5446772B2 - Mg-Al composite oxide particle powder and resin composition containing the Mg-Al composite oxide particle powder - Google Patents

Description

  The present invention is a hydrotalcite-type particle powder excellent in hygroscopicity and humidity control, and excellent in acid acceptability for trapping an acid generated by hydrolysis and degradation of a resin containing an acidic component anion such as acetic acid, and An Mg—Al-based composite oxide particle powder for heat-treating the hydrotalcite type particle powder and a resin composition containing the hydrotalcite type particle powder are provided.

  In recent years, solar cells that convert sunlight into electric energy have been actively developed from the viewpoint of ecology such as effective use of resources and prevention of environmental pollution.

  In general, a solar cell has a structure in which a silicon cell module sealed with a polymer is sandwiched between a glass substrate of a light receiving surface side protective layer and a protective member (back sheet) mainly composed of PET of a back surface side protective layer. Furthermore, it has a structure sealed by an aluminum frame. The glass substrate for the light-receiving surface protection layer, the back sheet for the back surface protection layer, and the aluminum frame used for the sealing material are used to protect solar cells installed outdoors from harsh natural environments (such as wind and rain). Yes.

  However, since solar cells are used outdoors for a long time exposed to high temperatures and high humidity and wind and rain, moisture passes through the protective layer (glass substrate, back sheet, aluminum frame) described above, and moisture becomes a sealing material. It may penetrate. Moisture that has penetrated to the inside of the solar cell (sealing material) corrodes the cell module inside the solar cell and significantly reduces the power generation efficiency and durability of the solar cell.

  In addition, as the sealing material for the cell module used inside the solar battery, it is preferable to use a material that has excellent water resistance and allows sunlight to pass through. Has been.

  However, although ethylene vinyl acetate copolymer is excellent in water resistance, hydrolysis gradually proceeds due to moisture permeated through the protective layer, and acetic acid is generated. The generated acetic acid corrodes the cell module inside the solar cell, and significantly reduces the durability of the solar cell.

  Conventionally, as a technique for preventing corrosion of electronic components due to moisture, a technique in which a polyethylene resin composition contains a water-absorbing filler such as molecular sieve or magnesium sulfate is known (Patent Document 1). By this method, the water that has penetrated into the resin composition is absorbed by the water-absorbing filler.

  In addition, as a technique for preventing erosion and corrosion of the cell module by acid, an acid acceptor for neutralizing acid such as magnesium hydroxide is included in the ethylene vinyl acetate copolymer used for the sealing material. Methods are known (Patent Document 2 and Patent Document 3). Acetic acid generated by this method can be neutralized, and corrosion of the cell module by acetic acid can be prevented.

  In addition, as a Mg-Al hydrotalcite particle powder for resin kneading, a particle powder having a large plate surface diameter and an appropriate thickness is known in consideration of dispersibility during resin kneading (Patent Literature). 4).

JP 2009-29964 A JP 2009-179810 A JP 2008-52277 A JP 2001-164042 A

  In the prior art, in Patent Document 1, although corrosion of the cell module due to moisture penetrating the sealing material can be prevented, acetic acid generated by hydrolysis of the ethylene-vinyl acetate copolymer caused by moisture penetration. It was difficult to say that the cell module could be sufficiently prevented from being corroded by acetic acid.

  Moreover, in patent document 2 and patent document 3, since it contains acid acceptors, such as magnesium hydroxide, it is possible to neutralize the acetic acid generated from the ethylene vinyl acetate copolymer. However, it is difficult to prevent hydrolysis of ethylene vinyl acetate copolymer due to moisture, so it is difficult to prevent moisture from penetrating into the sealing material. It was difficult to say that corrosion due to corrosion could be sufficiently prevented.

  Furthermore, in the prior art, it is difficult to arbitrarily change the refractive index, and when mixed with a resin having a large refractive index, the light transmittance decreases, and the power generation efficiency of the solar cell is remarkably high. It is thought that it will fall.

  In addition, the hydrotalcite-type particle powder described in Patent Document 4 is excellent in the ability to trap acid components such as acetic acid generated by hydrolysis of the resin due to the acid-accepting ability of the hydrotalcite-type particle powder. It is considered that it is difficult to prevent hydrolysis of the resin because it has a poor ability to absorb moisture that has penetrated into the resin.

  Accordingly, an object of the present invention is a hydrotalcite type that is excellent in hygroscopicity and humidity control, and has excellent acid acceptability for trapping acids generated by hydrolysis and degradation of resins containing acidic anions such as acetic acid. It is to provide a particle composition and a resin composition containing the hydrotalcite type particle powder.

  The technical problem can be achieved by the present invention as follows.

That is, the present invention provides Mg-M-Al having a core-shell structure in which Mg-Al hydrotalcite is used as a core particle and a hydrotalcite layer composed of aluminum and a divalent metal M is formed on the particle surface. It is a system hydrotalcite type particle powder, and the Mg-M-Al system hydrotalcite type particle powder is heat treated at 150 ° C. to 350 ° C. to dehydrate interlayer water, and is represented by the following composition formula (I). is a Mg-Al-based composite oxide particles obtained by heat treatment at 400 ° C. or more Ruha hydrotalcite-type particles (invention 1).
(Mg _1-y M _y ) _1-x · Al _x · (OH) ₂ · An ^n- _p · mH ₂ O (I)
(However, in the formula, x, y, and m are in the range of 0.2 ≦ x ≦ 0.5, 0.003 ≦ y ≦ 0.6, and 0 ≦ m <1, respectively)

Further, according to the present invention, the dehydration rate of the hydrotalcite-type particle powder described above is split into two on the [003] plane in the thickness direction of hydrotalcite where 2θ appears in the vicinity of 8 to 18 ° by powder X-ray diffraction. In the peak, the relative intensity ratio of the diffraction intensity of the peak appearing on the low angle side and the peak appearing on the high angle side is represented by the following formula (II).
Relative intensity ratio = low angle side [003] plane diffraction intensity / high angle side [003] plane diffraction intensity (II)
It is Mg-Al type complex oxide particle powder obtained using the hydrotalcite type particle powder represented by these, and the relative intensity ratio is 0.1-1000 (invention 2).

In the present invention, the divalent metal M in the formula (I) described above is one or more elements selected from Mg, Ca, Fe, Ni, Co, and Mn, and at least one or more elements are selected. It is Mg-Al type complex oxide particle powder in which a bivalent metal is contained in the shell layer (Invention 3).

In the present invention, the content of the divalent metal M present in the shell layer of the hydrotalcite-type particle powder described above is the molar equivalent of magnesium contained in the core particle and the divalent metal M in the shell layer. It is Mg-Al type complex oxide particle powder whose ratio M / Mg is 0.05 to 0.6, and whose refractive index is 1.48 to 1.70 (Invention 4).

The present invention also includes the Mg-Al composite oxide particle powder and the ethylene vinyl acetate copolymer described above , and the Mg-Al composite oxide particle powder is an ethylene vinyl acetate copolymer. This is a resin composition containing 0.1 to 80 parts by mass with respect to 100 parts by mass (Invention 5).

The hydrotalcite-type particle powder according to the present invention has excellent hygroscopicity and humidity control properties, and excellent acid-accepting ability to trap acids generated by hydrolysis and degradation of resins containing acidic anions such as acetic acid. Therefore, it is suitable as a filler for the resin composition.
Moreover, the resin composition using the hydrotalcite-type particle powder according to the present invention has both a high level of moldability and hygroscopicity to the resin during film formation.

  The configuration of the present invention will be described in more detail as follows.

  First, the hydrotalcite-type particle powder according to the present invention will be described.

  The structure of the hydrotalcite-type particle powder according to the present invention has Mg-Al hydrotalcite as a core particle, and a hydrotalcite layer composed of aluminum and a divalent metal M is formed on the particle surface of the particle. This is a hydrotalcite-type particle powder obtained by heat-treating Mg-M-Al-based hydrotalcite-type particle powder having a core-shell structure to dehydrate interlayer water.

The composition formula of the hydrotalcite-type particle powder according to the present invention is a compound represented by the following formula (I).
(Mg _1-y M _y ) _1-x · Al _x · (OH) ₂ · An ^n- _p · mH ₂ O (I)
0.2 ≦ x ≦ 0.5,
0.003 ≦ y ≦ 0.6,
0 ≦ m <1,
p = x / n,
An: n-valent anion

  Examples of the divalent metal represented by M include at least one selected from Mg, Ca, Fe, Ni, Cu, Co, and Mn, and it is sufficient that at least one divalent metal is contained. If necessary, two or more kinds of divalent metals can be contained.

The hydrotalcite type particle powder according to the present invention preferably has a BET specific surface area of 5 to 150 m ² / g. More preferably, it is 7-125 m < ² > / g, More preferably, it is 8-100 m < ² > / g. In hydrotalcite particles having a BET specific surface area of less than 5 m ² / g, since the specific surface area is too small, it is difficult to obtain sufficient acid-accepting ability and hygroscopic capacity, and when the BET specific surface area exceeds 150 m ² / g, Aggregation of particles becomes intense, and uniform dispersion in the resin becomes difficult.

  The hydrotalcite-type particle powder according to the present invention has an average plate surface diameter of 0.01 to 1.0 μm. Preferably it is 0.02-0.8 micrometer, More preferably, it is 0.02-0.7 micrometer. When the average plate surface diameter is less than 0.01 μm, the dispersibility in the resin is insufficient. If it exceeds 1.0 μm, it is difficult to produce industrially.

  The hydrotalcite-type particle powder according to the present invention preferably has a thickness of 0.005 to 0.1 μm.

In addition, the dehydration rate of the hydrotalcite-type particle powder according to the present invention is a peak split into two in the thickness direction [003] plane of hydrotalcite that appears in the vicinity of 8-18 ° by 2X by powder X-ray diffraction. It can be represented by the relative intensity ratio of the diffraction intensity of the peak appearing on the low angle side (hydrotalcite containing interlayer water) and the peak appearing on the high angle side (brucite oxide with dehydrated interlayer water). The dehydration rate is represented by the relative intensity ratio of the following formula (II).
Relative intensity ratio = low angle side [003] plane diffraction intensity / high angle side [003] plane diffraction intensity (II)

  In that case, the relative strength ratio of the hydrotalcite-type particle powder according to the present invention is preferably 0.1 to 1000. More preferably, it is 0.2-800, More preferably, it is 0.25-500. If it is less than 0.1, the interlayer water has been dehydrated more than necessary, and the acetic acid generated in the resin has been lost to the moisture that leads it into the interlayer, and sufficient acid acceptability is exhibited. Can not. On the other hand, when it exceeds 1000, the content of interlayer water is large, and the function of absorbing and conditioning moisture in the resin is lowered.

  The content of the divalent metal M present in the shell layer of the hydrotalcite-type particle powder according to the present invention is the molar equivalent ratio M / Mg of magnesium contained in the core particle and the divalent metal M in the shell layer. The refractive index of the particles is adjusted in the range of 1.48 to 1.70.

  In the hydrotalcite-type particle powder according to the present invention, the residual acetic acid concentration in the solution according to the evaluation method described later is preferably less than 150 ppm, more preferably less than 100 ppm. In the case of 150 ppm or more, the acid acceptability is insufficient.

  The kind of anion contained in the hydrotalcite-type particle powder according to the present invention is not particularly limited. For example, hydroxide ion, carbonate ion, sulfate ion, phosphate ion, silicate ion, organic carboxylate ion , Organic sulfonate ions, and organic phosphate ions.

  The hydrotalcite-type particle powder according to the present invention has at least one surface selected from a higher fatty acid, an anionic surfactant, a higher fatty acid phosphate ester, a coupling agent, and a polyhydric alcohol ester, if necessary. You may coat | cover with a processing agent. By coating with a surface coating, the dispersibility of the hydrotalcite-type particle powder in the resin is improved, and further enhancement of the function and stabilization of the resin is possible.

  Examples of the higher fatty acid include lauric acid, stearic acid, palmitic acid, oleic acid, and linoleic acid. Examples of the higher fatty acid phosphoric acid ester include stearyl ether phosphoric acid, oleyl ether phosphoric acid, and lauryl ether phosphoric acid. Examples of the polyhydric alcohol ester include sorbitan monooleate, sorbitan monolaurate, and stearic acid monoglyceride.

Examples of the anionic surfactant include salts such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium stearate, potassium oleate, and castor oil potassium.

  As the coupling agent, silane-based, aluminum-based, titanium-based, zirconium-based coupling agents and the like can be used.

  The amount when the surface treatment agent is coated on the hydrotalcite-type particle powder according to the present invention is preferably 0.2 to 20.0% by weight in terms of C with respect to the hydrotalcite particles, more preferably 0.5. ˜18.0% by weight. When the coating amount is less than 0.2% by weight, no improvement in function or dispersibility due to coating is observed. If it exceeds 20.0% by weight, the coating effect is saturated, so it is meaningless to coat more than necessary.

  Next, a method for producing the hydrotalcite type particle powder according to the present invention will be described.

  An alkaline aqueous solution containing an anion, a magnesium salt aqueous solution and an aluminum salt aqueous solution are mixed to obtain a mixed solution having a pH value in the range of 10 to 14, and then the mixed solution is aged in a temperature range of 40 to 105 ° C. -The core particles of Al-based hydrotalcite-type particles are formed (primary reaction), and then the total moles of the magnesium and the aluminum added to the aqueous suspension containing the core particles when the core particles are formed After the addition of the aqueous solution containing the divalent metal M and aluminum at a ratio such that the total number of moles is 0.50 or less, the pH value is in the range of 8-11 and the temperature is in the range of 60-200 ° C. It can be obtained by aging (secondary reaction).

  The alkaline aqueous solution containing anions in the present invention is preferably a mixed alkaline aqueous solution of an aqueous solution containing anions and an aqueous alkali hydroxide solution.

  As the aqueous solution containing anions, aqueous solutions such as sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, sodium sulfate, organic carboxylate, organic sulfonate, and organic phosphate are preferable.

  As the alkali hydroxide aqueous solution, sodium hydroxide, potassium hydroxide, ammonia, urea aqueous solution and the like are preferable.

  As the magnesium salt aqueous solution in the present invention, a magnesium sulfate aqueous solution, a magnesium chloride aqueous solution, a magnesium nitrate aqueous solution and the like can be used, and a magnesium sulfate aqueous solution and a magnesium chloride aqueous solution are preferable. A slurry of magnesium oxide powder or magnesium hydroxide powder may be substituted.

  As the aluminum salt aqueous solution in the present invention, an aluminum sulfate aqueous solution, an aluminum chloride aqueous solution, an aluminum nitrate aqueous solution and the like can be used, and an aluminum sulfate aqueous solution and an aluminum chloride aqueous solution are preferable. A slurry of aluminum oxide powder or aluminum hydroxide powder may be substituted.

  In the primary reaction, the mixing order of the alkaline aqueous solution containing anions, magnesium and aluminum is not particularly limited, and each aqueous solution or slurry may be mixed simultaneously. Preferably, an aqueous solution or slurry in which magnesium and aluminum are mixed in advance is added to an aqueous alkali solution containing anions.

  Moreover, when adding each aqueous solution, you may carry out either when adding this aqueous solution at once, or when dripping continuously.

  As for the density | concentration in the reaction solution which mixed the alkali aqueous solution containing the anion in a primary reaction, magnesium, and aluminum, 0.1-1.5 mol / l of magnesium is preferable, More preferably, it is 0.1-1.2 mol / l. , Aluminum is preferably 0.03 to 1.0 mol / l, more preferably 0.04 to 0.8 mol / l, and an anion is preferably 0.05 to 1.4 mol / l, more preferably 0.06. -1.2 mol / l, alkali is preferably 0.5-8 mol / l, more preferably 0.8-6 mol / l. The ratio of magnesium to aluminum to be added (Mg / Al) is preferably 0.8 to 5.0, more preferably 0.9 to 4.5.

  The temperature during the ripening reaction in the primary reaction is 40 to 105 ° C, preferably 45 to 105 ° C. Hydrotalcite-type particle powder is produced even at a temperature lower than 40 ° C., but core particles of hydrotalcite-type particles having a large plate surface diameter cannot be obtained.

  The pH value during the ripening reaction in the primary reaction is 10 to 14, preferably 11 to 14. When the pH value is less than 10, the core particle of hydrotalcite type particles having a large plate surface diameter and an appropriate thickness cannot be obtained.

  The reaction time of the ripening reaction in the primary reaction is preferably 2 to 24 hours. When the aging time is less than 2 hours, it is difficult to obtain hydrotalcite-type core particles having a large plate surface diameter and an appropriate thickness. Aging over 24 hours is not economical.

  At the end of the primary reaction, magnesium and aluminum do not remain in the reaction suspension, and all contribute to the formation of hydrotalcite-type core particles. Therefore, the composition of the core particles is estimated to be the same as the charged composition.

The hydrotalcite-type core particles obtained by the primary reaction preferably have an average plate surface diameter of 0.008 to 0.9 μm, a thickness of 0.004 to 0.07 μm, and a BET specific surface area value of 5 to 150 m. ² / g is preferred.

  In the secondary reaction, the total number of moles of the divalent metal M and aluminum is 0.50 or less with respect to the total number of moles of magnesium and aluminum added in the primary reaction. Preferably it is 0.45 or less. When added in excess of 0.50 with respect to the total number of moles of the primary reaction, in addition to forming a shell layer, a large number of out-of-form particles are generated alone, resulting in a hydrous having a uniform core-shell structure. No talcite particles can be obtained.

  In the secondary reaction, the order of adding the divalent metal M and aluminum is not particularly limited, and each aqueous solution or slurry may be added simultaneously. Preferably, an aqueous solution or slurry in which the divalent metal M and aluminum are mixed in advance is added.

  Moreover, when adding each aqueous solution, you may carry out either when adding this aqueous solution at once, or when dripping continuously.

  The total metal concentration in the mixed solution of the divalent metal M and aluminum in the secondary reaction is preferably 0.1 to 1.5 mol / l, more preferably 0.1 to 1.2 mol / l.

  The temperature during the ripening reaction in the secondary reaction is 45 ° C to 105 ° C, preferably 60 to 105 ° C. Even when the temperature is lower than 45 ° C., it is possible to promote particle growth, but stable synthesis is difficult, and a large number of fine particles having a fine particle diameter are generated. Thereafter, in order to obtain desired particles, it is effective to perform the aging by extending the reaction time or raising the temperature to 105 ° C. or higher, and the temperature range is 105 ° C. to 200 ° C.

  The pH value during the ripening reaction in the secondary reaction is 8 to 11, preferably 8 to 10. When the pH value is less than 8, hydrotalcite particles having a large plate surface diameter and an appropriate thickness cannot be obtained. If the pH exceeds 11, a part of the added divalent metal may remain in the aqueous solution without precipitating, so it is neither economical nor industrial.

  The reaction time of the ripening reaction in the secondary reaction is preferably 2 to 24 hours. When the aging time is less than 2 hours, it is difficult to obtain hydrotalcite particles having a large plate surface diameter and an appropriate thickness. Aging over 24 hours is not economical.

  At the end of the secondary reaction, the divalent metal and aluminum do not remain in the reaction suspension, and all contribute to the formation of hydrotalcite particles. Therefore, the composition of the hydrotalcite layer coated on the surface of the core particle is estimated to be the same as the charged composition in the growth reaction.

  After completion of the reaction, if filtered, washed with water and dried by a conventional method, Mg-Al hydrotalcite is used as core particles, and Mg-Al hydrotalcite is formed on the particle surface (outer shell) of the core particles. -M-Al hydrotalcite type particle powder is obtained.

  In the hydrotalcite type particle powder according to the present invention, the Mg-M-Al hydrotalcite type particle powder is heat-treated in a temperature range of 150 to 350 ° C, preferably 180 to 320 ° C. The heat treatment time may be adjusted depending on the heat treatment temperature. The atmosphere during the heat treatment may be either an oxidizing atmosphere or a non-oxidizing atmosphere, but it is better not to use a gas having a strong reducing action such as hydrogen.

  The coating with the surface treatment agent can be performed by either a dry surface treatment or a wet surface treatment. When performing dry surface treatment, put Mg-M-Al hydrotalcite-type particle powder into a Henschel mixer, sand mill, edge runner, Taninaka grinder, rakai machine, etc., add the surface treatment agent and dry mix And grind.

  When wet surface treatment is performed, an aqueous suspension such as a higher fatty acid salt is added to an aqueous suspension obtained by dispersing Mg-M-Al hydrotalcite-type particle powder, and the temperature is adjusted to 20 to 95 ° C. Then, by mixing and stirring, or if necessary, by adjusting the pH value after mixing and stirring, the particle surface of the Mg-M-Al-based hydrotalcite-type particles is coated, and then filtered, washed with water, Dry and grind. In the case of further heat treatment, an arbitrary surface treatment agent that does not decompose at the heat treatment temperature is selected.

  When the surface treatment agent is decomposed at a desired heat treatment temperature, a dry surface treatment using a Henschel mixer or the like may be performed after the heat treatment. When performing the dry surface treatment, the Mg-M-Al hydrotalcite-type particle powder and the surface treatment agent may be heated from the outside if necessary while being pulverized and mixed.

  As the surface treatment agent, higher fatty acids, higher fatty acid phosphate esters, polyhydric alcohol esters, anionic surfactants, coupling agents and the like as described above can be used.

  The coating amount on the particle surface is 0.2 to 20.0% by weight in terms of C with respect to the Mg-M-Al hydrotalcite particle powder. When it is less than 0.2% by weight, it is difficult to coat a sufficient amount of higher fatty acid on the particle surface. If it exceeds 20.0% by weight, the coating effect is saturated, so there is no point in adding more than necessary.

  Next, the Mg—Al based composite oxide particle powder according to the present invention will be described.

The Mg—Al composite oxide particle powder according to the present invention preferably has an average plate surface diameter of 0.05 to 1.0 μm, a thickness of 0.005 to 0.1 μm, and a BET of 5 to 150 m ² / g. The residual concentration in the solution is less than 150 ppm, and the refractive index is preferably 1.48 to 1.70.

  The Mg—Al composite oxide particle powder according to the present invention can be obtained by heat-treating the hydrotalcite particle powder at 400 ° C. or higher. The atmosphere during the heat treatment may be either an oxidizing atmosphere or a non-oxidizing atmosphere, but it is better not to use a gas having a strong reducing action such as hydrogen.

  Next, a method for producing the Mg—Al composite oxide particle powder according to the present invention will be described.

  The Mg—Al composite oxide particle powder of the present invention can be obtained by subjecting the hydrotalcite type particle powder to a heat treatment at 400 ° C. or higher. The heat treatment is preferably performed in a temperature range of 400 to 900 ° C.

  Next, the resin composition according to the present invention will be described.

  It is a resin composition having acid acceptability and humidity control ability, containing the hydrotalcite-type particle powder according to the present invention. Examples of the resin include ethylene vinyl acetate, polyvinyl formal, polyvinyl butyral, polyvinyl acetal, vinyl chloride resin, and epoxy resin. An ethylene vinyl acetate copolymer is preferable, and the resin can be mixed as necessary.

  The resin composition according to the present invention preferably contains 0.1 to 80 parts by mass of the hydrotalcite-type particle powder with respect to 100 parts by mass of the resin. When content of the said hydrotalcite particle is less than 0.1, the effect as an acid acceptor and a humidity control agent is low. When the amount exceeds 80 parts by mass, the transparency of the resin is deteriorated, which adversely affects the power generation efficiency of the solar cell.

  Various additives can be blended in the resin composition of the present invention as necessary. Examples of such additives include known crosslinking agents, adhesion improvers, ultraviolet absorbers, light stabilizers, antioxidants, and the like.

  As a crosslinking agent, an organic peroxide or a photopolymerization initiator can be added. Examples of the organic peroxide include tertiary butyl peroxyisopropyl carbonate, tertiary butyl peroxyacetate, tertiary butyl peroxybenzoate, dicumyl peroxide, 2,5-dimethyl-2,5-bis (tertiary butyl Peroxy) hexane and the like.

  A silane coupling agent can be added as an adhesion improver. For example, a silane coupling agent having a group having an unsaturated group such as a vinyl group or an acryloxy group, an amino group, an epoxy group, or an alkoxy group can be used. Specifically, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, γ-glycine. Sidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and the like.

  Antioxidants include hindered phenols and phosphorus, light stabilizers include hindered amines and benzoates, and ultraviolet absorbers include benzotriazoles, triazines, and benzophenones.

  Next, a method for producing the resin composition according to the present invention will be described.

  The resin composition of the present invention is obtained by kneading by a known method using an additive such as a resin such as an ethylene vinyl acetate copolymer, hydrotalcite-type particle powder, and, if necessary, a crosslinking agent. I can do it. For example, when a film-like molded product is obtained, the film may be molded after kneading using an ordinary extruder or hot roll. A conventional inflation method, a T-die method, or the like can be used for forming the film.

  Next, examples and comparative examples are given.

  Various characteristics of the hydrotalcite type particle powder and the resin composition according to the present invention were evaluated by the following methods.

  The constituent phase of the Mg-M-Al hydrotalcite-type particle powder having a core-shell structure was identified with an X-ray diffractometer (RINT-2500, manufactured by Rigaku Corporation). Measurement was performed under the conditions of a diffraction angle 2θ of 3 to 80 °, a step angle of 0.03 °, and an FT of 0.3 sec. Cu was used as the radiation source type.

  The plate surface diameter of the Mg-M-Al-based hydrotalcite-type particle powder having a core-shell structure is the average value of the values measured using a transmission electron microscope (manufactured by JEOL Ltd., JEM-1200EXII). It is.

  The thickness of the Mg-M-Al-based hydrotalcite-type particle powder having a core-shell structure was measured by an X-ray diffractometer as in the constituent phase identification. From the diffraction peak curve of the [006] crystal plane of the hydrotalcite-type particle powder, using Cu as the radiation source type, tube voltage 40 kV, tube current: 300 mA, step angle 0.01 °, FT 0.1 sec. The values are calculated using Scherrer's formula.

  The composition of the Mg-M-Al hydrotalcite-type particle powder having a core-shell structure is obtained by dissolving the hydrotalcite-type particle powder with an acid and using a plasma emission spectrometer (iCAP6500, manufactured by Thermo Electron Co., Ltd.) with yttrium. Was used as an internal standard.

  The specific surface area value was measured by the BET method using nitrogen. As a measuring apparatus, “Monosorb MS-21 (manufactured by QUANTA CHROME) was used.

In addition, carbonate ion content when carbonate ion (CO ₃ ²⁻ ) is used as an anion (An ⁿ⁻ ), and higher fatty acid, higher fatty acid phosphate ester, polyhydric alcohol ester, anionic surfactant on the particle surface, The coating amount with a coupling agent or the like was evaluated by measuring the carbon content (% by weight) with “Carbon Sulfur Analyzer: EMIA-2200 (manufactured by HORIBA)”. The coating amount of the particle surface with higher fatty acid, higher fatty acid phosphate ester, polyhydric alcohol ester, anionic surfactant, coupling agent and the like was evaluated from the increase in carbon content before and after the surface treatment.

  The residual concentration of the hydrotalcite-type particle powder in the solution was prepared by preparing an aqueous solution with an acetic acid concentration of 1000 ppm, and adding 1 g of hydrotalcite particles to 100 ml of the aqueous solution and allowing to stand for 48 hours, and filtering the solution. The content of acetic acid contained in the filtrate was measured using an ion chromatograph.

  The refractive index of the hydrotalcite-type particle powder was measured based on JIS K0062. That is, measurement was performed by the Becke method using “Abbe refractometer: 3T (manufactured by Atago)” at 23 ° C. using α-bromonaphthalene and DMF as solvents.

The weight reduction rate of the hydrotalcite type particle powder was calculated by the following calculation formula.
Weight reduction rate (wt%) = ({weight before heat treatment−weight after heat treatment} / weight before heat treatment) × 100

The moldability of the resin composition containing hydrotalcite-type particle powder was evaluated by measuring the total light transmittance (transparency) of the film. When the dispersion of the hydrotalcite-type particle powder in the resin is insufficient, the total light transmittance (transparency) is lowered due to the aggregated particles, and thus the above evaluation was used as a judgment criterion for moldability. Judgment criteria for formability by total light transmittance evaluation were set as follows. In addition, the following total light transmittance is a relative total light transmittance when the total light transmittance of only the ethylene vinyl acetate copolymer is 100%.
○: Total light transmittance is 90% or more Δ: Total light transmittance is 85% or more and less than 90% ×: Total light transmittance is less than 85%

  The hygroscopicity of the resin composition containing the hydrotalcite-type particle powder is the mass before and after moisture absorption after 48 hours at 25 ° C. and 80% RH using the above-mentioned film cut into 5 cm × 5 cm as a sample. Obtained by change.

  Next, a method for producing a resin composition will be described.

  A predetermined amount of hydrotalcite-type particle powder was mixed with 100 parts by weight of ethylene vinyl acetate, supplied to a normal hot roll, kneaded and then molded to prepare a film-like resin composition having a thickness of 1 mm.

Example 1
A mixture of 500 ml of an aqueous solution of sodium carbonate having a CO ₃ ^2- ion concentration of 0.84 mol / l, 341 ml of an aqueous solution of sodium hydroxide of 18.4 mol / l (pH value = 14.2) and 500 ml of water was maintained at 60 ° C. Stir in the reaction vessel. A mixed solution of 750 ml of a 1.92 mol / l magnesium sulfate aqueous solution and 250 ml of a 0.96 mol / l aluminum sulfate aqueous solution was added thereto to make a total amount of 1.5 l. While stirring the reaction vessel, the mixture was aged for 2 hours at 60 ° C. with a pH value of 12.8 to produce a white precipitate (core particle 1). The obtained hydrotalcite particles had a plate surface diameter of 0.15 μm, a thickness of 0.030 μm, and a specific surface area of 18.6 m ² / g.

Subsequently, a mixed solution of 250 ml of a 1.35 mol / l magnesium sulfate solution and 250 ml of a 0.47 mol / l aluminum sulfate aqueous solution was added over 30 minutes to make the total volume 2 l, and the pH value was 9. 7. Aged at 60 ° C. for 1 hour to form a white precipitate. The ratio of the total number of moles of magnesium and aluminum added by the shell reaction to the total number of moles of magnesium and aluminum added by the above reaction is 0.15. The suspension was transferred to an autoclave and aged with stirring at 160 ° C. for 6 hours to promote particle growth of the Mg—M—Al hydrotalcite having a core-shell structure. The obtained hydrotalcite-type particle powder had a plate surface diameter of 0.14 μm, a thickness of 0.040 μm, and a specific surface area of 19.2 m ² / g.
The slurry containing the white precipitate was filtered, washed with water, and dried at 120 ° C. to obtain white particle powder. As a result of identifying the crystal phase of this white particle powder by X-ray diffraction, it was confirmed to be a hydrotalcite type particle powder.

Next, the obtained hydrotalcite-type particle powder was heat-treated at 260 ° C. for 1 hour to dehydrate the interlayer water. The obtained hydrotalcite-type particle powder had a plate surface diameter of 0.14 μm, a thickness of 0.033 μm, and a specific surface area of 45.3 m ² / g. Further, analysis by powder X-ray diffraction revealed that the relative intensity ratio of the split [003] plane was 1.2. It was confirmed that non-dehydrated hydrotalcite and dehydrated hydrotalcite were present at approximately 1: 1. The weight reduction rate after the heat treatment was 12.1 wt%.

  Next, 10 parts by weight of hydrotalcite-type particle powder and 90 parts by weight of ethylene vinyl acetate copolymer (trade name: LV-440) were mixed and kneaded with a normal hot roll at 145 ° C. for 10 minutes, and then the thickness was increased. A 1 mm film-shaped resin composition was obtained. The film-shaped resin composition obtained had good moldability and the moisture absorption rate was 3.4%.

Examples 2-5, Comparative Examples 1-3
Except for various changes in the type and concentration of magnesium compound and divalent metal, the type and concentration of aluminum compound, the concentration of sodium carbonate salt, the concentration of alkaline aqueous solution, the aging temperature and the heat treatment temperature, Similarly, Mg-M-Al hydrotalcite particles were obtained. Moreover, the film-shaped resin composition was obtained using the hydrotalcite particle | grains obtained similarly.

Example 6
The hydrotalcite-type particle powder of Example 1 was heat-treated again at a temperature of 700 ° C. for 1 hour to obtain a Mg—Al-based composite oxide particle powder. The average plate surface diameter of the obtained Mg—Al-based composite oxide particle powder was 0.14 μm, the thickness was 0.033 μm, and the specific surface area was 75.4 m ² / g. Moreover, the weight reduction rate was changed from 12.1 wt% to 40.1 wt% by heat treating Example 1 again.

  Tables 1 and 2 show the synthesis conditions of Examples and Comparative Examples, Table 3 shows the properties of the obtained hydrotalcite particles, Table 4 shows the synthesis method and properties of the Mg-Al-based composite oxide particles, Table 5 shows the properties of the obtained resin composition.

  As shown in Table 5, the resin composition containing the hydrotalcite-type particle powder or Mg-Al-based composite oxide particle powder according to the present invention has a total light transmittance of 90% or more and a moisture absorption rate of 0. Since it is as low as 0.1 to 5%, it was confirmed that it has high transparency and excellent hygroscopicity.

  The hydrotalcite-type particle powder according to the present invention has excellent hygroscopicity and humidity control properties, and excellent acid-accepting ability to trap acids generated by hydrolysis and degradation of resins containing acidic anions such as acetic acid. Therefore, it is suitable as a filler for the resin composition.

Claims (5)

Mg-M-Al hydrotalcite type having a core-shell structure in which Mg-Al hydrotalcite particles are used as core particles and a hydrotalcite layer composed of aluminum and a divalent metal M is formed on the particle surface. The Mg-M-Al-based hydrotalcite-type particle powder is heat treated at 150 ° C. to 350 ° C. to dehydrate the interlayer water, whereby the following formula (I)
(Mg _1-y M _y ) _1-x · Al _x · (OH) ₂ · An ^n- _p · mH ₂ O (I)
(Wherein x, y and m are in the range of 0.2 ≦ x ≦ 0.5, 0.003 ≦ y ≦ 0.6 and 0 ≦ m <1, respectively). Mg-Al composite oxide particle powder obtained by heat-treating mold particle powder at 400 ° C or higher. The dehydration rate of the hydrotalcite-type particle powder according to claim 1 has a low angle at a peak split into two in the thickness direction [003] plane of hydrotalcite where 2θ appears in the vicinity of 8 to 18 ° by powder X-ray diffraction. The relative intensity ratio of the diffraction intensity of the peak appearing on the side and the peak appearing on the high angle side is represented by the following formula (II)
Relative intensity ratio = low angle side [003] plane diffraction intensity / high angle side [003] plane diffraction intensity (II)
Mg-Al-based composite oxide particle powder obtained by using hydrotalcite-type particle powder represented by the following formula and having a relative intensity ratio of 0.1 to 1000. The divalent metal M in the formula (I) according to claim 1 is one or more elements selected from Mg, Ca, Fe, Ni, Co, Mn, and at least one divalent metal is Mg—Al based composite oxide particles contained in the shell layer. The content of the divalent metal M present in the shell layer of the hydrotalcite-type particle powder according to claim 1 is a molar equivalent ratio M / Mg of magnesium contained in the core particle and the divalent metal M of the shell layer. Mg-Al based composite oxide particles having a refractive index of 0.05 to 0.6 and a refractive index of the particles of 1.48 to 1.70. To any one of claims 1 to 4 wherein the Mg-Al-based composite oxide particles and ethylene-vinyl acetate copolymer according, and, the Mg-Al-based composite oxide particles ethylene vinyl acetate copolymer 100 The resin composition which contains 0.1 mass part-80 mass parts with respect to a mass part.