JP6301208B2 - Highly active magnesium oxide additive and its use - Google Patents

Description

  The present invention relates to a highly active magnesium oxide-based additive, a rubber composition containing the magnesium oxide-based additive, a resin composition, an adhesive composition (hereinafter also referred to as “rubber composition etc.”) and the rubber composition It is useful as a technique for improving acid acceptability, scorch resistance, tensile strength, viscosity, dispersibility, etc. of a rubber composition, etc., regarding a molded article using a material.

  Conventionally, magnesium oxide is inexpensive, chemically stable, has basic properties and has non-toxic properties, so chlorine generated during processing of acid acceptors such as resins and chloroprene rubber Has been used as an anti-scorch agent that adsorbs and prevents premature crosslinking of rubber (for example, Non-Patent Document 1). However, conventional magnesium oxide does not have good dispersibility in resins and rubbers, and functions as acid acceptors and scorch inhibitors are not sufficient. Material physical properties were reduced.

In response to the above problem, magnesium oxide particles having high dispersibility in rubber or the like have been proposed (see, for example, Patent Document 1). In Patent Document 1, the scorch resistance and tensile strength are improved by using highly dispersible magnesium oxide having a BET specific surface area of 10 to 200 m ² / g and an average particle diameter of 0.1 to 1.5 μm. It has been described that it has the effect of making it. However, according to the study by the present inventors, the magnesium oxide described in Patent Document 1 has insufficient activity, and there is room for further improvement in the function as an acid acceptor and a scorch inhibitor.

JP-A-2-141418

Gosei Kanari et al., “Relationship between characteristic values of domestic magnesium oxide and physical properties of sulfur-modified CR”, Journal of Japan Rubber Association, Vol. 37, No. 7 (1964), p. 42-48

  Therefore, an object of the present invention is a highly active magnesium oxide system that is highly active, can sufficiently function as an acid acceptor and a scorch preventive agent, and does not cause deterioration in physical properties of the material even when combined with rubber or the like. An object is to provide an additive, a rubber composition containing the magnesium oxide-based additive, and a molded body using the rubber composition.

  As a result of intensive studies, the present inventor can solve the above-mentioned problems by using highly active magnesium oxide particles prepared through a step of wet-grinding magnesium hydroxide slurry as a raw material before firing. As a result, the present invention has been completed.

That is, the magnesium oxide-based additive of the present invention includes magnesium oxide particles having a BET specific surface area of 80 m ² / g or more and 300 m ² / g or less and CAA 40% of 30 seconds or less or a surface treatment product thereof. Features. Various physical property values in the present invention are values measured by the methods employed in the examples.

  According to the magnesium oxide-based additive of the present invention, the BET specific surface area and CAA 40% of the magnesium oxide particles are within the above ranges and are highly active. Can also exert a sufficient function. Thereby, mechanical properties such as scorch resistance and tensile strength can be improved even when blended with rubber or the like.

  In the above, the average particle size of the dry particle size distribution of the magnesium oxide particles is preferably 5 μm or more and 10 μm or less. With such an average particle size, dispersibility in resin and rubber and chlorine adsorption are improved, and an appropriate BET specific surface area and CAA of 40% are easily obtained, and the effects of the present invention can be obtained more reliably. It becomes easy.

Moreover, it is preferable that the peak of log differential pore volume when the pore radius of the magnesium oxide particles is 3 nm or more and 4 nm or less is 300 mm ³ / g or more and 500 mm ³ / g or less. With such a log differential pore volume, dispersibility in resin and rubber and chlorine adsorption are improved, and an appropriate BET specific surface area and CAA of 40% are easily obtained, and the effects of the present invention can be obtained more reliably. It becomes easy to be done.

On the other hand, magnesium hydroxide as a raw material for magnesium oxide particles undergoes a step of firing magnesium hydroxide having a BET specific surface area of 30 m ² / g to 70 m ² / g and a sedimentation volume of 35 mL to 95 mL. It is preferable to be obtained. Thereby, the magnesium oxide particle or magnesium oxide type additive which satisfy | fills the characteristic of a desired level can be obtained efficiently.

  The magnesium oxide based additive of the present invention includes higher fatty acids, higher fatty acid alkaline earth metal salts, coupling agents, esters composed of fatty acids and polyhydric alcohols, and phosphate esters composed of phosphoric acid and higher alcohols. It is preferable that the surface treatment is performed with at least one surface treatment agent selected from the group consisting of: By using such a surface-treated product, dispersibility in rubber or the like or a molded product can be further improved.

  The composition of the present invention preferably contains a magnesium oxide-based additive and rubber, resin, or adhesive. Thereby, since the magnesium oxide type additive of the present invention functions as an acid acceptor and a scorch inhibitor, mechanical properties such as scorch resistance and tensile strength can be improved.

  The composition of the present invention comprises at least one resin selected from the group consisting of ABS resin, polypropylene resin, polystyrene resin, polycarbonate resin, polyphenylene resin, polyester resin and polyamide resin as the resin. It is preferable to contain.

  In the above, since the magnesium oxide-based additive of the present invention is blended as an acid acceptor, the strength of the molded product obtained from the composition can be made to a sufficient level, and the acid present at the time of resin preparation Discoloration due to components or the like can be efficiently prevented.

  The composition of the present invention includes rubber, chloroprene rubber, acrylic rubber, nitrile rubber, isoprene rubber, urethane rubber, ethylene propylene rubber, chlorosulfonated polyethylene, epichlorohydrin rubber, silicone rubber, styrene-butadiene rubber, butadiene rubber, fluorine rubber. And at least one rubber selected from the group consisting of polyisobutylene rubber.

  In the above, since the magnesium oxide-based additive of the present invention is blended as an anti-scorch agent, it is possible to prevent early crosslinking progress in storage of the composition or the molded product thereof, and the magnesium oxide-based additive Due to the good dispersibility, it is possible to prevent deterioration in appearance such as so-called lumps in which particles are agglomerated.

  Moreover, it is preferable that the molded object of this invention is obtained from the composition containing the said magnesium oxide type additive. As a result, the magnesium oxide-based additive of the present invention is blended as an acid acceptor and an anti-scorch agent, so that the strength of the molded product can be improved and discoloration can be prevented. Can do.

[Magnesium oxide additive]
The magnesium oxide-based additive of the present invention contains magnesium oxide particles or a surface treatment product thereof. The magnesium oxide particles in the present invention are composed of powder containing magnesium oxide as a main component, and the proportion of magnesium oxide as a main component is preferably 95% or more, more preferably 98% or more, and even more preferably 99% or more. . In addition, the impurity component derived from a raw material can be included. Moreover, the component which can be mix | blended with resin, rubber | gum, etc. can also be contained in the range which does not impair the effect of this invention. In general, magnesium oxide can be produced by firing a magnesium raw material such as magnesium hydroxide or magnesium carbonate as a raw material. In this invention, it is preferable to contain the magnesium oxide powder obtained through the process of wet-grinding the magnesium hydroxide slurry used as a raw material before baking. In general, magnesium oxide is inexpensive, chemically stable, has basic properties and has non-toxic properties, so it prevents early crosslinking of acid acceptors such as resins and rubbers such as chloroprene rubber. It functions as a scorch inhibitor.

The magnesium oxide-based additive of the present invention has high activity because the BET specific surface area of the magnesium oxide particles is 80 m ² / g or more and 300 m ² / g or less, and CAA 40% is 30 seconds or less. It is useful as a functional additive for rubber or the like such as anti-scorch agent.

BET specific surface area of the magnesium oxide particles contained in the magnesium oxide-based additive, ^{80 m} 2 / g or more 300m and ² / g or less, ^90m 2 / g or more 280m is preferably from ² / g, 100 m ² / g or more 260 meters ² / G or less is more preferable. When the BET specific surface area is within the above range, the dispersibility of the magnesium oxide-based additive is improved and the activity is increased, so that the acid accepting action and the rubber composition when the resin composition is obtained. Scorch-preventing properties are also fully exhibited. When the BET specific surface area is less than 80 m ² / g, the acid accepting action when the resin composition is used decreases, causing discoloration of the molded article, or the scorch prevention property when the rubber composition is used is reduced and stored. Stability is reduced. Moreover, when a BET specific surface area exceeds 300 m < ² > / g, there exists a possibility that the dispersibility to resin etc. may fall.

  The upper limit of CAA 40% of magnesium oxide particles contained in the magnesium oxide-based additive may be 30 seconds or less, but is preferably 28 seconds or less, and more preferably 26 seconds or less. When it is within the above range, the strength of the obtained rubber composition or the molded product is ensured, and mechanical properties such as scorch resistance can be achieved. When the CAA of 40% exceeds 30 seconds, the activity decreases and the scorch resistance and the tensile strength in the case of a rubber composition or the like are lowered. On the other hand, the lower limit of CAA 40% is preferably 10 seconds or more, and more preferably 15 seconds or more from the viewpoint of ease of production.

When the BET specific surface area was 80 m ² / g or more and 300 m ² / g or less, it was difficult to obtain magnesium oxide particles having a CAA of 40% within the above range by the conventional production method. However, it has become possible to make CAA 40% within the above range by passing through a process of wet-grinding magnesium hydroxide as a raw material before firing as in the present invention. That is, the magnesium oxide-based additive of the present invention is preferably obtained through a step of wet-grinding magnesium hydroxide before firing.

  The upper limit of the average particle size in the dry particle size distribution of the magnesium oxide particles contained in the magnesium oxide-based additive is preferably 10 μm or less, more preferably 9.5 μm or less, and even more preferably 9 μm or less. On the other hand, the lower limit of the average particle diameter is preferably 5 μm or more, more preferably 5.3 μm or more, and even more preferably 5.5 μm or more. Within the above range, mechanical properties such as scorch prevention can be achieved while securing the strength of the resulting rubber composition or the molded product. In the wet particle size distribution which is a conventional measurement method, there is no difference in the measurement result of the average particle diameter even with particles having good rubber properties or bad particles, but there is a clear difference in the measurement result with the dry particle size distribution. This is probably because the wet particle size distribution failed to reflect the characteristics of the microparticles due to the decrease in van der Waals force between the particles and the electrostatic energy barrier generated between the particles. One of the causes is thought to be easily affected by the solvent. On the other hand, in the dry particle size distribution, it is possible to measure the average particle size without being affected by the above problem. The present inventor believes that fine particles have better physical properties of rubber and resin, and it is presumed that the average particle size is large due to the strong aggregation of fine particles in the dry particle size distribution.

The upper limit of the peak (maximum value) of the log differential pore volume when the pore radius of the magnesium oxide particles contained in the magnesium oxide-based additive is 3 nm or more and 4 nm or less is preferably 500 mm ³ / g or less, and is 490 mm ³ / g or less. More preferred is 480 mm ³ / g or less. The lower limit of the peak (maximum value) of the log differential pore volume is preferably 300 mm ³ / g or more, more preferably 305 mm ³ / g or more, and still more preferably 310 mm ³ / g or more. When the log differential pore volume is within the above range, the chlorine adsorption performance of the magnesium oxide-based additive becomes good, the strength of the resulting rubber composition or molded product is improved, and mechanical properties such as scorch prevention Will be fully demonstrated.

The BET specific surface area of magnesium hydroxide, which is a raw material of the magnesium oxide particles contained in the magnesium oxide-based additive, is preferably 30 m ² / g or more and 70 m ² / g or less, and 33 m ² / g or more and 67 m ² / g or less. Is more preferably 35 m ² / g or more and 65 m ² / g or less. When the BET specific surface area is within the above range, mechanical properties such as scorch prevention properties are sufficiently exhibited while ensuring the strength of the rubber composition or the like obtained in the magnesium oxide-based additive after firing. become.

  The sedimentation volume of magnesium hydroxide, which is a raw material for the magnesium oxide particles contained in the magnesium oxide-based additive, is preferably 35 mL to 95 mL, more preferably 37 mL to 90 mL, and even more preferably 40 mL to 85 mL. When the sedimentation volume is within the above range, the dispersibility of the magnesium oxide-based additive becomes good, and mechanical properties such as scorch prevention are sufficiently exhibited while ensuring the strength of the rubber composition or the molded product. become.

  The magnesium oxide based additive of the present invention may be a surface treated product obtained by surface treating magnesium oxide particles with a surface treating agent. As the surface treatment agent, a known compound used for the application can be used. The surface treatment is selected from the group consisting of higher fatty acids, higher fatty acid alkaline earth metal salts, coupling agents, esters composed of fatty acids and polyhydric alcohols, and phosphate esters composed of phosphoric acid and higher alcohols. It is preferable to carry out using at least one kind. According to this configuration, since the magnesium oxide-based additive is treated with the predetermined surface treatment agent, the dispersibility of the magnesium oxide-based additive in the resin, etc. is improved, and the resin composition, rubber composition, and adhesion thereby The physical properties of the agent composition and the molded product can be maintained or improved. In addition, a surfactant can also be used as the surface treatment agent.

  Examples of the higher fatty acid include higher fatty acids having 10 or more carbon atoms such as stearic acid, erucic acid, palmitic acid, lauric acid, and behenic acid, and stearic acid is preferable in terms of dispersibility and handling properties. Examples of the higher fatty acid alkaline earth metal salt include the alkaline earth metal salts of the higher fatty acids described above. As the alkaline earth metal, beryllium, magnesium, calcium, strontium, barium, radium, or the like can be preferably used. . From the viewpoint of dispersibility, higher fatty acid alkaline earth metal salts are preferable, and among these, magnesium stearate is more preferable. These may be used alone or in combination of two or more.

  Examples of the coupling agent include γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and γ-methacryloxypropyltriethoxysilane. Γ-acryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, p-trimethoxysilylstyrene, p-triethoxysilylstyrene, p-trimethoxysilyl-α-methylstyrene, p-triethoxysilyl -Α-methylstyrene 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2 (aminoethyl) 3-aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltri Toxisilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-propyl-3-aminopropyltri Silane coupling agents such as methoxysilane, 4-aminobutyltrimethoxysilane, decyltrimethoxysilane, isopropyltriisostearoyl titanate, isopropyltris (dioctylpyrophosphate) titanate, isopropyltri (N-aminoethyl-aminoethyl) Examples include titanate coupling agents such as titanate and isopropyltridecylbenzenesulfonyl titanate, and aluminum coupling agents such as acetoalkoxyaluminum diisopropylate. It is. Such coupling agents may be used alone or in combination of two or more.

  Examples of esters composed of a fatty acid and a polyhydric alcohol include esters of a polyhydric alcohol such as glycerin monostearate and glycerin monooleate with a fatty acid.

  Examples of phosphoric acid esters composed of phosphoric acid and higher alcohol include mono- or diesters such as orthophosphoric acid and oleyl alcohol, stearyl alcohol, or a mixture of both, such as acid forms or alkaline earth metal salts thereof. Phosphate ester etc. are mentioned.

  As the surfactant, a nonionic surfactant can be suitably used. Nonionic surfactants include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene alkyl ether such as polyoxyethylene higher alcohol ether, polyoxyethylene Polyoxyethylene alkyl aryl ethers such as nonylphenyl ether; polyoxyethylene derivatives; sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan sesquioleate Sorbitan fatty acid esters such as sorbitan distearate; polyoxyethylene sorbitan monolaurate, polyoxy Polyoxyethylene sorbitan such as Tylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate Fatty acid esters; Polyoxyethylene sorbitol fatty acid esters such as polyoxyethylene sorbitol tetraoleate; Glycerin fatty acid esters such as glycerol monostearate, glycerol monooleate, and self-emulsifying glycerol monostearate; Polyethylene glycol monolaurate, polyethylene glycol Monostearate, polyethylene glycol distearate, polyethylene glycol Polyoxyethylene fatty acid esters, such as oleate polyoxyethylene alkylamine, polyoxyethylene hardened castor oil, alkyl alkanol amide.

  In order to perform surface treatment of the magnesium oxide particles using such a surface treatment agent, a known dry method or wet method can be applied. As a dry method, the surface treatment agent may be added in a liquid, emulsion, or solid state with stirring using a mixer such as a Henschel mixer, and mixed sufficiently under heating or non-heating. As a wet method, magnesium oxide powder is added to a non-aqueous solvent slurry in a solution state or an emulsion state, and mechanically mixed at a temperature of, for example, about 1 to 100 ° C., and then dried to a non-aqueous solvent. Can be removed. Examples of the non-aqueous solvent include isopropyl alcohol and methyl ethyl ketone. The addition amount of the surface treatment agent can be selected as appropriate. However, when the dry method is adopted, the surface treatment level is likely to be non-uniform compared to the wet method. Therefore, the addition amount is slightly larger than the wet method. good. Specifically, the range of 0.5-10 mass% is preferable with respect to 100 mass% of magnesium oxide particles, and the range of 1-5 mass% is more preferable. When the wet method is adopted, the range of 0.1 to 5% by mass with respect to 100% by mass of the magnesium oxide particles is preferable from the viewpoint of sufficient surface treatment and prevention of aggregation of the surface treatment agent, and 0.3 to 3% by mass. The range of is more preferable.

  The surface-treated magnesium oxide-based additive is selected as appropriate by means such as granulation, drying, pulverization, and classification as required, and the final product (acid acceptor, scorch inhibitor) It can be.

[Method for producing magnesium oxide-based additive]
Magnesium oxide particles contained in magnesium oxide-based additives are prepared by reacting water-soluble magnesium salt, seawater or irrigation with an aqueous alkali metal hydroxide, alkaline earth metal hydroxide or aqueous ammonia solution. A step of performing a seed crystal reaction at 1 ° C. or higher and 100 ° C. or lower once on the dispersion to obtain a raw material for baking, and a step of baking the raw material for baking at 350 ° C. or higher and 900 ° C. or lower. Can be obtained. In the present invention, it is particularly preferable to produce a magnesium oxide-based additive through a step of further wet-grinding a magnesium hydroxide slurry obtained as a raw material for firing.

  Preferable examples of the water-soluble magnesium salt that can be used in this step include magnesium chloride hexahydrate, magnesium chloride dihydrate, and anhydrous magnesium chloride. Usually, the water-soluble magnesium salt is used as an aqueous solution. In addition, seawater and irrigation may be used as the magnesium raw material. The magnesium ion concentration in each aqueous solution is preferably 0.01 to 5 mol / L, more preferably 0.05 to 4 mol / L, from the viewpoint of sufficiently proceeding the reaction.

  As the alkali metal hydroxide that is an alkali raw material, sodium hydroxide, potassium hydroxide, or the like can be used. Further, as the alkaline earth metal hydroxide, magnesium hydroxide, calcium hydroxide, or the like can be used. The alkali concentration of the aqueous alkali solution may be about 0.1 to 18N, and preferably 0.5 to 15N.

  A dispersion containing magnesium hydroxide can be prepared by reacting the water-soluble magnesium salt prepared in the above procedure with an aqueous alkali solution at about 1 to 100 ° C. for 0.01 to 10 hours.

  In the case of adopting a seed crystal reaction (a method of obtaining particles by crystal growth from a seed crystal) in this step, the dispersion obtained above is used as a seed, and the same magnesium chloride aqueous solution as the magnesium raw material is added thereto, Furthermore, the procedure of adding and stirring an aqueous alkali solution such as sodium hydroxide is a one-cycle seed crystal reaction, and a magnesium hydroxide slurry can be prepared by repeating this procedure for 1 to 50 cycles. The magnesium ion concentration during the seed crystal reaction is preferably 0.05 to 4 mol / L from the viewpoint of sufficiently allowing the reaction to proceed. Moreover, as an alkali concentration of aqueous alkali solution, about 0.5-15N is preferable. As stirring temperature after mixing magnesium chloride aqueous solution and alkaline aqueous solution, 1-100 degreeC is preferable, 5-95 degreeC is more preferable, and 10-90 degreeC is further more preferable. Moreover, as stirring time, 0.01 to 10 hours are preferable and 0.1 to 8 hours are more preferable. The obtained seed crystal slurry is vacuum-filtered and then sufficiently washed with water and emulsified by adding water to prepare a magnesium hydroxide slurry.

  In order to obtain a highly active magnesium oxide-based additive having a desired level of CAA of 40%, the magnesium hydroxide slurry prepared in the above process is preferably subjected to a wet grinding process before firing. The wet pulverization is not particularly limited as long as it can be used in a wet manner such as a ball mill, a tower mill, a circular vibration mill, a spiral driven vibration mill, a planetary pulverizer, a sand grinder, an atomizer, a pulperizer, a supermicron mill, and a colloid mill. Among these, a ball mill is used from the viewpoint of making the magnesium hydroxide slurry fine.

  Although the material is not particularly limited, it is preferable to use a ball-shaped medium such as alumina or zirconia in a ball mill lined with silica, alumina, rubber or the like. The concentration of the magnesium hydroxide slurry is generally preferably 5% by mass or more and 20% by mass or less, and more preferably 7% by mass or more and 18% by mass or less. By subjecting this magnesium hydroxide slurry to wet pulverization for about 0.1 to 10 hours at a rotational speed of 50 to 200 rpm in an alumina pot mill, magnesium hydroxide as a firing raw material can be obtained.

  Magnesium oxide particles in the present invention can be obtained by firing magnesium hydroxide for firing in a heating furnace at 350 to 900 ° C. for 0.1 to 8 hours and then pulverizing as necessary.

  The obtained magnesium oxide particles may be subjected to a surface treatment according to the surface treatment procedure as necessary.

[Resin composition]
The resin agent composition in the present invention is a resin composition in which a magnesium oxide-based additive is blended with a predetermined resin. The magnesium oxide-based additive can suitably function as an acid acceptor for neutralizing the catalyst component and acid component present in the system during the preparation of the resin.

  The resin contained in the resin composition is preferably at least one selected from the group consisting of ABS resins, polypropylene resins, polystyrene resins, polycarbonate resins, polyphenylene resins, polyester resins, and polyamide resins. These may be selected according to the application.

  In the resin composition, the magnesium oxide-based additive is blended in an amount of 0.01 to 5 parts by weight, preferably 0.05 to 3 parts by weight, more preferably 0.1 to 100 parts by weight of the resin. 1 part by mass is blended. By making the blending amount of the magnesium oxide-based additive within the above range, the function as an acid acceptor can be sufficiently exhibited, and the desired physical properties and appearance of the resin composition or molded body can be prevented by preventing aggregation. Can be demonstrated.

  You may mix | blend another additive other than the said component with the said resin composition in the range which does not impair the effect of this invention. Examples of such additives include antioxidants, antistatic agents, pigments, foaming agents, plasticizers, fillers, reinforcing agents, flame retardants, crosslinking agents, light stabilizers, UV absorbers, and lubricants. It is done.

  Although the compounding quantity of said other additive is not specifically limited from a viewpoint that the effect of this invention should not be impaired, It is preferable to mix | blend 0.1-10 mass parts with respect to 100 mass parts of said resins.

[Rubber composition]
The rubber composition in the present invention is a rubber composition in which a magnesium oxide-based additive is blended with a predetermined rubber. The magnesium oxide-based additive can suitably function as a scorch prevention agent for preventing the progress of crosslinking during storage of the rubber composition and facilitating molding and vulcanization in the next step.

  The rubber contained in the resin composition includes chloroprene rubber, acrylic rubber, nitrile rubber, isoprene rubber, urethane rubber, ethylene propylene rubber, chlorosulfonated polyethylene, epichlorohydrin rubber, silicone rubber, styrene-butadiene rubber, butadiene rubber, and fluorine rubber. And at least one selected from the group consisting of polyisobutylene rubber. These may be selected according to the application.

  In the rubber composition, 0.01 to 10 parts by mass, preferably 0.1 to 8 parts by mass, more preferably 1 to 6 parts by mass of the magnesium oxide-based additive is blended with respect to 100 parts by mass of the rubber. By making the blending amount of the magnesium oxide-based additive within the above range, the function as a scorch inhibitor can be sufficiently exerted, and the desired physical properties and appearance of the rubber composition or molded body can be prevented by preventing aggregation. Can be demonstrated.

  In the rubber composition, various additives can be blended as in the case of the resin composition as long as the effects of the present invention are not impaired.

[Adhesive composition]
The adhesive composition in the present invention is an adhesive composition in which a magnesium oxide-based additive is blended with a predetermined adhesive. When the magnesium oxide-based additive of the present invention is blended with an adhesive, the adhesive strength of the adhesive composition can be improved in the same manner as when blended with a resin.

  As an adhesive contained in the adhesive composition, in addition to an adhesive containing a resin blended in the above resin composition, a rubber adhesive, an epoxy adhesive, a cyanoacrylic adhesive, a vinyl adhesive , Silicone rubber adhesive, vinyl acetate adhesive and the like.

  In the said adhesive composition, it is preferable to mix | blend 4-10 mass parts magnesium oxide type additive with respect to 100 mass parts of said adhesive agents. By setting the blending amount of the magnesium oxide-based additive within the above range, the adhesive strength of the adhesive composition can be improved as in the case of blending with the resin.

[Molded body]
The molded body can be obtained using the rubber composition, resin composition, or adhesive composition. Such a molded body can be obtained by a known molding method after blending a predetermined amount of a magnesium oxide-based additive into a resin or the like. Examples of such a molding method include extrusion molding, injection molding, and calendar molding.

  Since the predetermined magnesium oxide-based additive described above is blended in the molded body, it has excellent impact strength and excellent appearance of the molded product. Such a molded body can be used for various applications that require impact resistance and the like. For example, OA equipment, automobile parts (interior / exterior parts), game machines, building members (indoor use), electrical products (air conditioners, refrigerators) Outside, so-called housing applications for electronic and electrical equipment in general), miscellaneous goods, stationery, furniture, musical instruments (recorders), machine parts, and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to a following example, unless the summary is exceeded.

[Example 1]
16.7 L of seawater prepared to a pH = 3 with sulfuric acid as a magnesium raw material was weighed in a 200 L polyethylene container. This aqueous NaOH 180mL of 8.3N was added slowly with stirring as an alkali material ^{(Mg 2+} moles: OH ^- is the number of moles was 1: 1.8) to prepare a Mg _{(OH) 2} suspension . Using this Mg (OH) ₂ suspension as a seed, 16.7 L of seawater was added from above, and 180 mL of an 8.3N NaOH aqueous solution was slowly added with stirring, followed by stirring for 5 minutes, and the first seed crystal. Reaction was performed. Such seed crystal reaction was repeated a total of 8 times. The obtained seed crystal slurry is subjected to vacuum filtration, then sufficiently washed with 20 times or more of pure water with respect to Mg (OH) ₂ solid content, emulsified by adding pure water, and 10 g / dL Mg (OH) ₂ concentration A slurry was prepared. 1 L of this slurry was collected and poured into an alumina pot mill having a capacity of 3 L in which 1 kg of an alumina ball having a diameter of 3 mm was charged. This pot mill was rotated at 100 rpm for 30 minutes and wet pulverized. The wet-pulverized slurry was vacuum filtered, dried, and then pulverized with a bantam mill to obtain a raw material a-1 for firing Mg (OH) ₂ powder.

  A 300 mL alumina crucible was charged with 100 g of the raw material a-1, fired at 450 ° C. for 2 hours using an electric furnace, and then pulverized with a bantam mill to obtain a MgO powder sample A-1.

[Example 2]
16.7 L of seawater prepared to pH = 3 with sulfuric acid as a magnesium raw material was weighed into a 100 L polyethylene container. This aqueous NaOH 180mL of 8.3N was added slowly with stirring as an alkali material ^{(Mg 2+} moles: OH ^- is the number of moles was 1: 1.8) to prepare a Mg _{(OH) 2} suspension . Using this Mg (OH) ₂ suspension as a seed, 16.7 L of seawater was added from above, and 180 mL of an 8.3N NaOH aqueous solution was slowly added with stirring, followed by stirring for 5 minutes, and the first seed crystal. Reaction was performed. Such seed crystal reaction was repeated three times in total. Except these series of operations, the same operation as the preparation of the raw material a-1 and the sample A-1 of Example 1 was performed to obtain the raw material a-2 and the sample A-2.

[Example 3]
In Example 1, except that baking of the raw material a-1 was performed at 430 ° C. for 1.5 hours, MgO powder was produced under exactly the same conditions as in Example 1 to obtain Sample A-3.

[Comparative Example 1]
In a 15 L polyethylene container, 480 g of high-purity MgCl ₂ .6H ₂ O as a magnesium raw material was weighed, and 1 L of pure water was added and stirred to prepare an MgCl ₂ aqueous solution. This aqueous NaOH 510mL of 8.3N was added slowly with stirring as an alkali material ^{(Mg 2+} moles: OH ^- is the number of moles was 1: 1.8) to prepare a Mg _{(OH) 2} suspension . Using this Mg (OH) ₂ suspension as a seed, an MgCl ₂ aqueous solution in which 480 g of high-purity MgCl ₂ .6H ₂ O was dissolved in 1 L of pure water was added, and 510 mL of an 8.3N NaOH aqueous solution was slowly added with stirring. After the addition, the mixture was stirred for 5 minutes to carry out the first seed crystal reaction. Such seed crystal reaction was repeated a total of 8 times. The obtained seed crystal slurry is subjected to vacuum filtration, sufficiently washed with 20 times or more of pure water with respect to Mg (OH) ₂ solid content, dried, pulverized with a bantam mill, and raw material for firing Mg (OH) ₂ powder b-1 was obtained. Except for these series of operations, the same operation as the preparation of Sample A-1 of Example 1 was performed to obtain Sample B-1.

[Comparative Example 2]
16.7 L of seawater prepared to a pH = 3 with sulfuric acid as a magnesium raw material was weighed in a 200 L polyethylene container. This aqueous NaOH 180mL of 8.3N was added slowly with stirring as an alkali material ^{(Mg 2+} moles: OH ^- is the number of moles was 1: 1.8) to prepare a Mg _{(OH) 2} suspension . Using this Mg (OH) ₂ suspension as a seed, 16.7 L of seawater was added from above, and 180 mL of an 8.3N NaOH aqueous solution was slowly added with stirring, followed by stirring for 5 minutes, and the first seed crystal. Reaction was performed. Such seed crystal reaction was repeated a total of 8 times. Except for these series of operations, the same operations as the preparation of the raw material b-1 and sample B-1 of Comparative Example 1 were performed to obtain the raw material b-2 and sample B-2.

[Comparative Example 3]
A natural brucite pulverized product having an average particle diameter of 3 μm was used as a raw material b-3. A 300 mL alumina crucible was charged with 100 g of the raw material b-3, baked at 450 ° C. for 2 hours using an electric furnace, and then pulverized with a bantam mill to obtain a MgO powder sample B-3.

[Analysis of raw powder and sample powder]
The raw material powder and the sample powder obtained in the examples and comparative examples were analyzed as follows. Table 1 shows the results of each analysis.

BET specific surface area: A measurement sample (magnesium oxide) pretreated for about 30 minutes at about 130 ° C. in a nitrogen gas atmosphere using an 8-unit preheat unit (manufactured by MOUNTECH) is used as a MacET HM Model as a BET specific surface area measuring device. -1208 (manufactured by MOUNTECH) and the like were measured by a nitrogen gas adsorption method.

  CAA 40%: 100 mL of 0.4N citric acid aqueous solution containing 1 drop of phenolphthalein indicator was placed in a 200 cc beaker and adjusted to 30 ° C. ± 0.5 ° C. After adding 4 g of the magnesium oxide powder weighed to the solution within 1 second, the solution was stirred by rotating a magnetic stirrer at 550 rpm simultaneously with the end of the addition. The time required from the start of stirring until the color of the measurement solution changed from colorless to reddish purple was measured, and this time (seconds) was taken as the value of CAA 40%.

  Average particle size of dry particle size distribution: For the sample powder, the refractive index of magnesium oxide is measured using a laser diffraction scattering type particle size distribution measuring device (LMS-2000e made by Seishin Enterprise) and a dispersion unit (2000D-One-Shot made by Seishin Company). A dry particle size distribution was determined under the conditions of 1.730 and a blowing pressure of 0.4 MPa. The particle diameter of 50% cumulative dry particle size distribution was defined as the average particle diameter.

  Average particle size of wet particle size distribution: As a pretreatment, 2.0 g of sample powder is put in a 100 ml beaker, solmix is added until the total amount becomes 50 ml, and 3 minutes with an ultrasonic homogenizer (UD-201 manufactured by Tommy Seiko Co., Ltd.) Dispersed. Immediately after the dispersion, the entire amount was added to a circulator (Microtrac VSR manufactured by Honeywell), and a wet particle size distribution was determined using a particle size analyzer (Microtrac HRA manufactured by Honeywell). The average particle size was defined as the 50% cumulative particle size of the wet particle size distribution.

  Log differential pore volume: Using a highly accurate fully automatic gas adsorption device (BELSORP 28SA manufactured by Nippon Bell Co., Ltd.), log differential pore volume by nitrogen gas adsorption at a constant bath temperature of 40 ° C. and an adsorption temperature of 77.0K. Asked.

  Sedimentation volume: A 100 mL graduated cylinder with a stopper was prepared by adding 5 g of raw material powder and pure water to a total volume of 100 mL and plugged. The graduated cylinder was shaken until the raw material powder was sufficiently diffused and then allowed to stand, and the value of the interface between the cloudy part and the transparent part after 2 hours was read to determine the sedimentation volume.

[Evaluation of rubber composition]
100 parts by mass of chloroprene rubber (manufactured by Showa Neoprene Co., Ltd., neoprene GNR) as a rubber component, 0.5 parts by mass of stearic acid, 2 parts by mass of phenyl-α-naphthylamine, 5 parts by mass of zinc oxide, 4 parts by mass of MgO sample powder The part was kneaded at room temperature for 5 minutes using a roll to obtain a chloroprene rubber composition.

  In the Mooney scorch test of the chloroprene rubber composition, the scorch time at a test temperature of 150 ° C. was measured using an L-type rotor according to JIS K6300. The target value for the scorch time was 13 minutes or more.

  A sheet obtained by vulcanizing the chloroprene rubber composition at 153 ° C. and 30 MPa for 15 minutes was punched into a No. 2 dumbbell according to JIS K7113, and the tensile strength was measured with a tensile tester (Autograph AG-5000A manufactured by Shimadzu Corporation). .

[Evaluation of resin composition]
100 parts by mass of ABS resin (EX-120 manufactured by UMG ABS Co., Ltd.) and 0.5 parts by mass of MgO sample powder were melt-kneaded at 220 ° C. for 5 minutes using a Laboplast mill (manufactured by Toyo Seiki). The kneaded product was cut into a diameter of 5 mm or less with a shredder to prepare a pellet-shaped resin composition. This resin composition was injection molded at an outlet temperature of 220 ° C. using an injection molding machine (manufactured by Nippon Steel Co., Ltd., J-50E2) to obtain an ABS test piece of width 12 mm × thickness 3 mm × length 65 mm. . The Izod impact strength of each ABS test piece was measured based on JIS K 7110.

  In order to examine the effect as an acid acceptor, each ABS test piece was placed in a gear oven at 100 ° C., and the color after 30 days was visually confirmed. The case where there was no change in the color was evaluated as “◯”, the case where there was almost no change in the color, “Δ”, and the case where the color changed, as “X”.

  The results of the above analysis and evaluation are shown in Table 1.

  As shown in Table 1, in Examples 1 to 3, a sufficient scorch time can be secured as a rubber composition, a sufficient strength can be secured as a tensile strength, and an acid acceptor for a resin composition. The effect of was also good. On the other hand, in Comparative Examples 1 to 3 in which the CAA time of 40% is too long, the scorch time is short, the tensile strength is insufficient, and the effect as an acid acceptor is also insufficient. This is considered to be because the time of CAA 40% became longer and the activity became lower.

Claims (9)

BET specific surface area of not more than ^{80 m} 2 / g or more 300 meters ² / g, and CAA40% is Ri der than 30 seconds,
Magnesium oxide-based additives containing magnesium oxide particles having an average particle size of 5 μm or more and 6.4 μm or less in a dry particle size distribution , or a surface treatment product thereof. 2. The magnesium oxide additive according to claim 1, wherein the magnesium oxide particles have an average particle size of a wet particle size distribution of 3.5 μm or more and 4.3 μm or less. ^{3. The} magnesium oxide-based additive according to claim 1, wherein the magnesium oxide particles have a log differential pore volume peak at a pore radius of 3 nm or more and 4 nm or less of 300 mm ³ / g or more and 500 mm ³ / g or less.   At least one selected from the group consisting of higher fatty acids, higher fatty acid alkaline earth metal salts, coupling agents, esters of fatty acids and polyhydric alcohols, and phosphate esters of phosphoric acid and higher alcohols The magnesium oxide additive according to any one of claims 1 to 3, which is surface-treated with a surface treatment agent.   The composition containing the magnesium oxide type additive of any one of Claims 1-4, and rubber | gum, resin, or an adhesive agent.   6. The resin according to claim 5, comprising at least one resin selected from the group consisting of an ABS resin, a polypropylene resin, a polystyrene resin, a polycarbonate resin, a polyphenylene resin, a polyester resin, and a polyamide resin. Composition.   As rubber, the group consisting of chloroprene rubber, acrylic rubber, nitrile rubber, isoprene rubber, urethane rubber, ethylene propylene rubber, chlorosulfonated polyethylene, epichlorohydrin rubber, silicone rubber, styrene-butadiene rubber, butadiene rubber, fluorine rubber and polyisobutylene rubber The composition according to claim 5, comprising at least one rubber selected from the group consisting of more than one rubber.   The molded object obtained from the composition of any one of Claims 5-7. A step of preparing a magnesium hydroxide slurry as a raw material for firing;
A process for wet pulverizing the magnesium hydroxide slurry, and a process for firing magnesium hydroxide obtained through the wet pulverization at 350 to 900 ° C., comprising :
A method for producing magnesium oxide, wherein the magnesium hydroxide has a BET specific surface area of 30 m ² / g or more and 70 m ² / g or less and a sedimentation volume of 35 mL or more and 95 mL or less .