JP2002265948A - Magnesium hydroxide flame retardant coated with silane coupling agent, its production method, and flame- retardant resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnesium hydroxide flame retardant which has been coated with a relatively cheap silane coupling agent, is excellent in compoundability and dispersibility into a polyolefin resin, and gives a resin composition excellent in mechanical properties and flame retardance. SOLUTION: In the method for preparing this magnesium hydroxide flame retardant, magnesium hydroxide is treated with a silane coupling agent by a wet process, then filtered with e.g. a filter press, and dried. More specifically, a specific silane coupling agent in a specified amount is added to magnesium hydroxide having a BET specific surface area of 10 m<2> /g or lower and stirred for at least a predetermined time; then, at least one compound selected from among unsaturated fatty acids and their metal salts and ammonium salts is added; and the resultant product is filtered to decrease the water content and is dried.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnesium hydroxide flame retardant used as a halogen-free flame retardant material,
The present invention relates to a method for producing the composition and a flame-retardant resin composition. More specifically, when blended with a polyolefin resin, it has excellent dispersibility in the resin and mechanical properties of the resin composition, and is relatively inexpensive. Is provided.

[0002]

2. Description of the Related Art Magnesium hydroxide is disclosed in, for example,
As disclosed in Japanese Patent Application Laid-Open No. 141929, for the purpose of preventing secondary disasters such as smoke, toxicity, and corrosion when the resin composition and the like are burned, it is used as a so-called non-halogen flame retardant in an olefin-based resin composition. ing. This non-halogen flame retardant is an alternative to halogen-based resin compositions that are conventionally used in large quantities as an environmentally friendly material that does not use halogens or heavy metals in the context of the social needs of preserving the global environment and ecology. It is suitable for materials and is being widely applied mainly to building materials such as wire coating and wallpaper.

However, the flame-retarding effect of magnesium hydroxide-based flame retardants is lower than that of halogen-based flame retardants, and when blended in polyolefin resins, etc., sufficient flame retardancy can be obtained unless incorporated in large amounts in the resins. I can't. In general, the greater the amount incorporated in the resin, the higher the flame retardancy, but the worse the dispersibility,
Mechanical properties such as tensile strength and elongation of the resin composition decrease.

For example, insulated wires used for internal wiring of electronic devices and wire harnesses of automobiles are required to pass a vertical combustion test, for example, in the United States UL standard from the viewpoint of safety against fire accidents of the devices. . In addition, electric wires for automobile wire harnesses are required to have flame retardancy that passes a combustion test at a 45 ° tilt in accordance with the ISO standard. However, when a magnesium hydroxide-based flame retardant is blended in a large amount in a polyolefin resin so as to pass these combustion tests, mechanical properties such as tensile strength and elongation are reduced. For example, in the UL standard and electrical appliance control standard, the tensile strength is 10MP.
a and elongation of 100% or more are required, and the CSA standard requires a tensile strength of 10 MPa or more and an elongation of 150% or more. However, these could not be achieved if a large amount of magnesium hydroxide was added to pass the combustion test.

As a method for solving such a problem, for example, Japanese Patent No. 2525968 discloses a method of blending a large amount of magnesium hydroxide without deteriorating mechanical properties, in which a crosslinking agent such as a silane coupling agent is blended. Thus, a method of performing chemical crosslinking or electron beam crosslinking during melt kneading or extrusion molding is disclosed. Also, for example, see JP-A-2000-23945.
According to No. 3, a composition with low melting torque and excellent moldability can be obtained by blending magnesium hydroxide that has been partially surface-treated with a cross-linking agent such as a silane coupling agent in advance rather than by a blending method. Is disclosed.
Further, JP-A-2000-294036 discloses that when a predetermined amount of magnesium hydroxide surface-treated with a crosslinkable silane coupling agent is blended, high flame retardancy and mechanical properties required for insulated wires for electronic devices are satisfied. It shows that you can do it.

[0006] Magnesium hydroxide flame retardants coated with a silane coupling agent for non-halogen flame retardant resin compositions have not yet obtained sufficient performance. That is, there is no known silane coupling agent-coated magnesium hydroxide-based flame retardant that satisfies all of the dispersibility when mixed with a resin, the mechanical properties of a resin composition, and the production cost.

There are roughly two methods for producing magnesium hydroxide coated with a silane coupling agent, a dry treatment method and a wet treatment method. In the dry treatment method, for example, while stirring the magnesium hydroxide powder with a Henschel mixer, spray-add the silane coupling agent solution using a spray or the like, sufficiently stir and mix the mixture, and then heat, dry, and pulverize to form a hydroxide. A magnesium-treated powder is obtained. In the wet treatment method, for example, a silane coupling agent solution is added to a suspension of magnesium hydroxide with stirring and mixed with stirring, followed by filtration with a filter press or the like, and heating, drying, and pulverizing the dehydrated cake, and adding water to the suspension. A magnesium oxide treated powder is obtained.

Further, Japanese Patent Application Laid-Open No. H11-349851 discloses that a suspension of magnesium hydroxide treated with a silane coupling agent is directly dried by heating with a spray drier or the like without being filtered and dehydrated and concentrated, and is subjected to silane coupling. It discloses obtaining an agent-coated magnesium hydroxide.

[0009]

SUMMARY OF THE INVENTION Magnesium hydroxide coated with a silane coupling agent obtained by a dry treatment method is not uniform when coated on a surface of the magnesium hydroxide particles with the silane coupling agent. The resin composition was poor in dispersibility, and the mechanical properties and flame retardancy of the resin composition were not sufficient. On the other hand, in the wet processing method, since it can be relatively uniformly coated with the silane coupling agent,
It has good dispersibility in resin, and provides sufficient mechanical properties and flame retardancy.

However, if magnesium hydroxide is treated with a silane coupling agent in a wet manner and then filtered with a filter press or the like, the silane coupling agent flows out together with the filtrate during filtration, resulting in a low yield and a sufficient amount of the treating agent. I can't. As a result, the dispersibility in the resin and the mechanical properties of the resin composition become insufficient.

In the above method, the BET specific surface area is 10 m
^{When a} silane coupling agent treatment is applied to ² / g or less of magnesium hydroxide, the dewatered cake has a very high tackiness and the dewatered cake is hard to peel off from the filter cloth. Due to such poor handling properties, line troubles are likely to occur and the production capacity is greatly reduced.

Further, as disclosed in JP-A-11-349851, a suspension of magnesium hydroxide treated with a silane coupling agent was directly heated and dried with a spray drier or the like, so that the suspension was treated with the silane coupling agent. The water content of the magnesium hydroxide suspension is 300 to 10
Since it is as high as 00%, the drying energy cost is high and its use is limited.

An object of the present invention is to provide a resin having good dispersibility,
An object of the present invention is to provide a magnesium hydroxide-based flame retardant coated with a silane coupling agent which is excellent in mechanical properties and is relatively inexpensive, a method for producing the same, and a flame-retardant resin composition. In particular, in the invention of the method for producing a magnesium hydroxide-based flame retardant, in addition to the above, the yield of the silane coupling agent is high,
An object of the present invention is to provide a method for producing a magnesium hydroxide-based flame retardant coated with a silane coupling agent, which has good handleability of a dehydrated cake and is easy to dry.

[0014]

[Means to solve the problem]

According to the present invention, the BET specific surface area is 10 m ² / g.
In the following, the methacryloxy-based silane coupling agent is used in an amount of 0.0
A silane coupling agent coating made of magnesium hydroxide containing 0.1 to 0.5 wt% of an unsaturated fatty acid having 2 to 2.0 wt% and having 12 or more carbon atoms and at least one of an alkali metal salt and an ammonium salt thereof; A magnesium hydroxide flame retardant (claim 1). Preferably, the magnesium hydroxide has an average particle size of 0.8 to 2.0 μm,
The ratio of magnesium hydroxide particles of 0.5 μm or less is 10 v
ol% or less (claim 2).

Further, according to the present invention, the BET specific surface area is 10 m ^2.
/ G of aqueous magnesium hydroxide solution: 1) 0.5-2.5 parts by weight of magnesium hydroxide
% Of a methacryloxy-based silane coupling agent and treated for 10 hours or more. 2) At least one of an unsaturated fatty acid having 12 or more carbon atoms and an alkali metal salt and an ammonium salt thereof is added to the weight of magnesium hydroxide. 3) Then, filtration is carried out so that the water content becomes 50% or less, and 4) drying, wherein the silane coupling agent-coated magnesium hydroxide is added. A method for producing a flame retardant (claim 3). The treatment with the silane coupling agent is performed under weak stirring or standing, and vigorous stirring such as crushing of magnesium hydroxide particles is not preferable. The magnesium oxide and the silane coupling agent are sufficiently reacted. Preferably, the magnesium hydroxide has an average particle size of 0.8 to 2.0 μm.
In this case, the ratio of particles having a size of 0.5 μm or less is 10 vol% or less (claim 4). It should be noted that the particle size of the magnesium hydroxide and the BET specific surface area hardly change under weak stirring or standing.

Further, according to the present invention, a magnesium hydroxide-based flame retardant coated with a silane coupling agent according to claim 1 or 2 is used in an amount of 50 to 3 based on 100% by weight of polyolefin resin.
It is a flame-retardant resin composition blended with 00 wt% (claim 5).

[0018]

The silane coupling agent used in the present invention is of a methacryloxy type, for example, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, Methacryloxypropyltriethoxysilane and the like can be mentioned. Vinyl-based, epoxy-based, amino-based silane coupling agents other than methacryloxy-based silane coupling agents have low surface treatment efficiency (yield), which is disadvantageous in terms of cost, dispersibility in resin and mechanical properties of resin composition. Physical properties are insufficient.

The silane coupling agent is treated for at least 10 hours after the addition, and if the treatment time is less than 10 hours, the surface treatment efficiency is not sufficient. The medium in which magnesium hydroxide is suspended is aqueous. The BET specific surface area of the magnesium hydroxide is less 10 m ² / g, BET specific surface area of 10 m ²
If it is larger than / g, secondary agglomeration is likely to occur, and the dispersibility in the resin and the mechanical properties of the resin composition decrease.

The amount of the silane coupling agent added is 0.5 to 2.5% based on the weight of magnesium hydroxide. If the addition amount is less than 0.5%, the content of the silane coupling agent in the flame retardant is insufficient, and the dispersibility in the resin and the mechanical properties of the resin composition decrease. If it is more than 2.5%, the elongation of the resin composition tends to decrease. Under the production conditions of the present invention, the addition amount of the silane coupling agent of 0.5 to 2.5% is 0.2 to 2.0% of magnesium hydroxide in the flame retardant.

In order to improve the handleability of the dehydrated cake, it is necessary to use an unsaturated fatty acid having 12 or more carbon atoms and at least one of alkali metal salts and ammonium salts thereof. Unsaturated fatty acids having 12 or more carbon atoms include, for example, lindelic acid (cis-4-dodecenoic acid),
4-tetradecenoic acid), fiseteric acid (cis-5-tetradecenoic acid), myristolic acid (cis-9-tetradecenoic acid), palmitoleic acid (cis-9-hexadecenoic acid),
Petroseric acid (cis-6-octadecenoic acid), oleic acid (cis-9-octadecenoic acid), elaidic acid (trans-
9-octadecenoic acid), ascrepic acid (cis-11-octadecenoic acid), vaccenic acid (trans-11-octadecenoic acid), gadoleic acid (cis-9-eicosenoic acid), gondoyic acid (cis-11-eicosenoic acid), Cetreic acid (cis
-11-docosenoic acid), erucic acid (cis-13-docosenoic acid), brassic acid (trans-13-docosenoic acid), secoleic acid (cis-15-tetracosenoic acid), xymenic acid (cis
-17-hexacosenic acid), lumecitric acid (cis-21-
Triacontenic acid) and the like. Examples of these alkali metal salts include Li, Na, and K salts.

An unsaturated fatty acid having 12 or more carbon atoms or an alkali metal salt or ammonium salt thereof is added in an amount of 0.1 to 0.5% by weight based on 100% by weight of magnesium hydroxide. The added unsaturated fatty acid having 12 or more carbon atoms or an alkali metal salt or ammonium salt thereof,
Almost 100% is adsorbed on magnesium hydroxide, and if the addition amount is less than 0.1%, the handleability of the dehydrated cake is low, and if the addition amount is more than 0.5%, the dispersibility in the resin and the resin composition Mechanical properties decrease.

The water content of the dewatered cake is set to 50% or less, and when the water content exceeds 50%, the handleability of the dewatered cake is reduced and the drying cost is increased.

The average particle size of the magnesium hydroxide is 0.8 to 2.0 μm, and the ratio of particles having a particle size of 0.5 μm or less is preferably 10 vol% or less. The ratio of particles whose average particle diameter is smaller than 0.8 μm or smaller than 0.5 μm is 10 vol.
%, The resin tends to re-agglomerate when blended with the resin, and the dispersibility in the resin and the mechanical properties of the resin composition are likely to decrease. When the average particle size is larger than 2.0 μm, the mechanical properties of the resin composition tend to decrease. Before and after the coupling agent treatment, the BET specific surface area and the average particle size of magnesium hydroxide, and the ratio of particles having a particle size of 0.5 μm or less hardly change.

The BET specific surface area is measured by the N ₂ adsorption method. The particle size distribution is measured by a laser diffraction method after suspending a sample in ethanol and performing a dispersion treatment with ultrasonic waves for 3 minutes.

[0026]

Example 1 The BET specific surface area was 6.0 m ² / g, the average particle size was 1.1 μm, and the ratio of particles having a particle size of 0.5 μm or less was 5.3 v.
ol% of magnesium hydroxide in water at a concentration of 200 g / liter, and 0.5 wt% of γ-methacryloxypropyltrimethoxysilane adjusted to pH 3.0 to 4.1 with acetic acid was added to magnesium hydroxide. 0.7% by weight of γ-methacryloxypropyltrimethoxysilane to 100% by weight
Was added so that

After the suspension was slightly stirred at room temperature for 20 hours,
5.0 wt% aqueous solution of sodium oleate (80 ° C)
Was added so that sodium oleate was 0.2% by weight based on the weight of magnesium hydroxide, and the mixture was stirred for 30 minutes. Next, the surface-treated slurry was filtered under reduced pressure, and then the dehydrated cake was put in a mold sandwiched between filter cloths and pressed under pressure to adjust the water content to 50% or less. The cake obtained by pressing under pressure was dried and pulverized to obtain a surface-treated magnesium hydroxide powder having a water content of about 0.2%.

[0028]

Example 2 The same operation as in Example 1 was carried out except that the stirring time after the addition of the silane coupling agent was changed to 10 hours.
A surface-treated magnesium hydroxide powder was obtained.

[0029]

Comparative Examples 1 to 4 Comparative Examples 1 to 4 were the same as in Example 1 except that the stirring time after the addition of the silane coupling agent was 5 hours.
A surface-treated magnesium hydroxide powder was obtained in the same manner as in Example 1, except for the following changes.

In the following, when the cake is pressed and squeezed, it is difficult to peel it off from the filter cloth, or when the squeezed cake is gently shaken by hand, water comes out of the cake (thixotropic property). In the case, it was evaluated as "x" which was poor in handling properties. Conversely, when the peeling from the filter cloth was good and there was no thixotropy, "O" indicating good handling was given.
The water content of the pressed cake was determined from the following equation. Cake moisture content (%) = (weight of cake−weight after drying) ÷ weight after drying × 100

The Si content of the obtained surface-treated magnesium hydroxide powder was measured by the ICP method, and the content of the silane coupling agent was determined by the following equation. The unit of the content is the content (wt%) of the coupling agent per 100 wt% of magnesium hydroxide. Silane coupling agent content = Si measured by ICP method
Value × molecular weight of silane coupling agent ÷ atomic weight of Si The silane coupling agent content when the amount added at the time of surface treatment is 100% is defined as the yield.

The surface-treated magnesium hydroxide powders obtained in Examples 1 and 2 and Comparative Examples 1 to 4 were mixed with a polyolefin resin, here a terpolymer of ethylene / ethyl acrylate / maleic anhydride (trade name, manufactured by Sumitomo Chemical Co., Ltd.) : Bondine TX-80
30, MFR: 3) 100 w% for each 100 wt%
t% was blended. Then, using a Toyo Seiki Labo Plastomill, the mixture was kneaded at 150 ° C. for 5 minutes at a rotation speed of 50 rpm, and the kneaded material was press-formed at 150 ° C. to form a sheet having a thickness of 2 mm. The formed 2 mm sheet was punched out into a dumbbell shape, and a tensile test (based on JIS K 7113) was performed using this. Table 1 shows the results. The content is the content of the silane coupling agent, the addition amount is 0.7 wt%, the moisture content and the handling property are the moisture content and the handling property of the dehydrated cake, and the tensile strength and the elongation are the tensile strength and the elongation of the resin composition. . The results are shown below.

[0033]

Table 1 Example 1 Example 2 Comparative Example 1 Silane cup γ-methacryloxy γ-methacryloxy γ-methacryloxylating agent cypropyltrimesipropyltrimesipropyltrimethoxysilane toxicsilane toxicsilane Stirring time (h) 20 10 5 content (%) 0.50 0.46 0.21 Yield (%) 70 70 30 Moisture content of cake (%) 43 45 42 Handleability ○ ○ ○ Tensile strength (MPa) 12 12 10 Elongation (%) 230 230 180 180 Comparative Example 2 Comparison Example 3 Comparative Example 4 Silane cup vinyltrimethy γ-glycidoxy N-β (aminoethyl) ring agent Xysilane propyltrimethy γ-aminopropylxysilane methyldimethoxysilane Stirring time (h) 20 20 20 Content (%) 0.16 0.16 12 0.09 Yield (%) 20 20 10 Moisture content (%) 41 44 42 Ndoringu resistant ○ ○ ○ Tensile strength (MPa) 10 9 9 elongation (%) 170 160 150

The mechanical properties required of the halogen-free flame-retardant resin composition are, for example, those having a tensile strength of 1 according to the CSA standard.
0 MPa or more and elongation is 150% or more. Insulated wires used for internal wiring of electronic devices and wire harnesses of automobiles include wires of various thicknesses, and thinner wires are more easily burned. In the case of a thin electric wire, the flame retardancy is maintained by increasing the filling amount of the magnesium hydroxide-based flame retardant, but the elongation decreases when the filling amount of the magnesium hydroxide-based flame retardant is increased. The mechanical properties were evaluated by blending 100% by weight of each of the magnesium hydroxide-based flame retardants of Examples and Comparative Examples with 100% by weight of a terpolymer of ethylene / ethyl acrylate / maleic anhydride. Then, assuming a case where the number of blended parts was increased to more than 100 wt%, the evaluation line for mechanical properties was set to a tensile strength of 10 MPa or more and an elongation of 200% or more.

As is clear from Table 1, when the stirring time after the addition of the surface treatment agent is as short as 5 hours or when a silane coupling agent other than methacryloxy is used, both the tensile strength and the elongation are mechanical. Did not reach the evaluation line for physical properties. In each of these comparative examples, the content of the silane coupling agent was smaller than that of the examples, and the yield was low. Although it is possible to increase the content of the silane coupling agent by increasing the amount of addition, the waste is large because the yield is low, and it is difficult to obtain the desired amount of the treatment agent. Therefore, the mechanical properties of the resin composition vary greatly.

[0036]

Examples 3-5 and Comparative Examples 5-6 Magnesium hydroxide having a BET specific surface area of 6.0 m ² / g, an average particle diameter of 1.1 μm, and a proportion of particles having a particle size of 0.5 μm or less of 5.3 vol% was used. 20
To a 0 g / L aqueous suspension, adjust the pH to 3.0 to 4.0 with acetic acid.
A 0.5 wt% aqueous solution of γ-methacryloxypropyltrimethoxysilane adjusted to 1 was added in the amount shown in Table 2. Then, the mixture was weakly stirred for 10 hours, and a 5.0 wt% aqueous solution of sodium oleate adjusted to 80 ° C. was added.
It was added to 2 wt% and stirred for 30 minutes. The obtained slurry was subjected to filtration, pressure pressing, drying, and pulverization in the same manner as in Example 1 to obtain a surface-treated magnesium hydroxide powder.

In the same manner as in Example 1, the content of the silane coupling agent, the water content of the cake, and the handleability of the cake were determined, and the mixture was further kneaded with an ethylene / ethyl acrylate / maleic anhydride terpolymer. To prepare a sheet, and a tensile test was performed. Table 2 shows the results.

[0038]

[Table 2] Example 3 Example 4 Example 5 Comparative Example 5 Comparative Example 6 Addition% 0.5 1.5 2.5 0.3 3.0 Content% 0.2 1.2 2.0 0 .1 2.4 Moisture content% 44 42 41 43 41 Handleability ○ ○ ○ ○ 引 張 Tensile strength MPa 12 13 14 915 Elongation% 230 220 210 180 180 160 * The amount of addition is in wt% unit with respect to 100 wt% of magnesium hydroxide. The amount of the silane coupling agent added; the content is the content of the silane coupling agent; the water content and the handling property are the water content and the handling property of the cake.

As is clear from Table 2, when the amount of the silane coupling agent is less than 0.5%, the content of the silane coupling agent is less than 0.2%, and the tensile strength and elongation are evaluated for mechanical properties. Did not reach the line. When the addition amount of the silane coupling agent is more than 2.5% and the content of the silane coupling agent is more than 2.0%, the resin composition becomes hard and the elongation becomes lower than the evaluation line of mechanical properties. .

[0040]

Examples 6-7 and Comparative Examples 7-12 In Examples 6-7 and Comparative Examples 7-11, the BET specific surface area shown in Table 3 was obtained.
The same operation as in Example 2 was performed using magnesium hydroxide having an average particle diameter and a ratio of particles of 0.5 μm or less to obtain a surface-treated magnesium hydroxide powder. In Comparative Example 12, a surface-treated magnesium hydroxide powder was obtained in the same manner as in Example 2, except that the dewatered cake was not pressed and pressed.

In the same manner as in Example 1, the water content of the cake and the cake handling properties were determined, and a sheet was prepared by kneading with a terpolymer of ethylene, ethyl acrylate and maleic anhydride, and a tensile test was conducted. . Table 3 shows the results.

[0042]

Table 6 Example 6 Example 7 Comparative Example 7 Comparative Example 8 BET specific surface area m ² / g 8.2 4.5 3.4 8.6 Average particle size μm 0.8 1.8 2.2 1.0 0.5 μm or less vol% 7.5 2.4 1.2 11.0 Water content % 45 43 40 45 Handleability ○ ○ ○ × Tensile strength MPa 14 12 10 9 Elongation% 210 230 180 150 150 Comparative example 9 Comparative example 10 Comparative example 11 Comparative example 12 BET specific surface area m ² / g 9.5 12.20 0.3 6.0 Average particle size μm 0.6 1.8 2.5 1.1 0.5 μm or less vol% 8.5 6.7 1.0 5.3 Moisture content% 47 43 45 60 Handleability × × ○ × Tensile strength MPa 10 9 8 13 Elongation% 170 160 130 230

As is apparent from Table 3, the BET specific surface area is larger than 10 m ² / g, and the average particle diameter is 0.8 μm or more.
The proportion of particles not in the range of 2.0 μm, 0.5 μm or less is more than 10 vol%, or the water content of the cake is 50%
When it exceeded, both cake handling properties and mechanical properties of the resin composition could not be satisfied.

[0044]

Examples 8 to 12 and Comparative Examples 13 to 17: BET specific surface area: 6.0 m ² / g, average particle diameter: 1.1 μm, 0.5 μm
A concentration of 200 g /
To a liter of magnesium hydroxide aqueous suspension, add acetic acid
A 0.5 wt% aqueous solution of γ-methacryloxypropyltrimethoxysilane in which H was adjusted to 3.0 to 4.1 was used, and a silane coupling agent was added in an amount of 0.5 to the weight of magnesium hydroxide.
7 wt% was added. Thereafter, the mixture was stirred for 10 hours. In Examples 8 to 11 and Comparative Examples 13 to 16, each additive in Table 4 was added as a 5.0 wt% aqueous solution (80 ° C). In Example 12 and Comparative Example 17, each additive in Table 4 was added as a 5.0 wt% ethanol solution. These samples were stirred for 30 minutes after each addition. Next, filtration, pressing, drying, and pulverization were performed in the same manner as in Example 1 to obtain a surface-treated magnesium hydroxide powder.

In the same manner as in Example 1, the water content of the cake and the cake handling property were determined, and the mixture was further kneaded with an ethylene / ethyl acrylate / maleic anhydride terpolymer to prepare a sheet, which was subjected to a tensile test. . Table 4 shows the results.

[0046]

Table 4 Example 8 Example 9 Example 10 Example 11 Example 12 Addition% of sodium oleate 0.1 0.5---Addition amount of sodium vacenoate%--0.3--Ammonium oleate Addition%---0.5-Oleic Acid Addition%----0.5 Sodium Stearate Addition%-----Sodium Obtusylate Addition%-----Oleic Amide Addition% − − − − − Moisture content% 43 43 43 43 43 43 Handleability ○ ○ ○ ○ ○ Tensile strength MPa 14 12 13 12 12 Elongation% 220 240 230 230 240 240 Comparison Comparison Comparison Comparison Comparison Example 13 Example 14 Example 15 Example 16 Example 17 Sodium oleate addition% 0.05 0.6---Sodium vacenoate addition%-----Ammonium oleate addition%----- Addition amount of oleic acid%-----Addition amount of sodium stearate--0.5--Addition amount of sodium ovtulate---0.5-Addition amount of oleic amide----0.5 water content %% 43 41 45 44 46 Handleability × ○ × × × Tensile strength MPa 129 91 119 Elongation% 200 180 50 210 210 160

As is clear from Table 4, under the conditions other than the examples, it was not possible to simultaneously satisfy both the cake handling properties and the mechanical properties of the resin composition.

The surface-treated magnesium hydroxide powder of Example 1 was mixed with 50 wt%, 100 wt%, and 100 wt% of ethylene / ethyl acrylate / maleic anhydride terpolymer.
A sheet was prepared in the same manner as described above by blending 200 wt%. These sheets were measured for oxygen index and subjected to a tensile test. Oxygen index of sheets 50 wt% blended surface treatment of magnesium hydroxide powder in 25vol% O _2, 36.5vol at 30.5vol% O _2, 200wt% compounded in 100 wt% blend
% Was O _2. Therefore, it can be seen that high flame retardancy can be obtained with 50 to 300 wt%. Also, when the content is 50 to 300 wt%, the tensile strength and elongation required for the halogen-free flame-retardant resin composition can be obtained.

[0049]

According to the present invention, a magnesium hydroxide flame retardant coated with a silane coupling agent, which is excellent in dispersibility in a resin, mechanical properties and flame retardancy of a resin composition, and is relatively inexpensive, can be obtained. When this flame retardant is mixed with the polyolefin resin, it becomes an environmentally friendly non-halogen flame retardant material.

In the method for producing a magnesium hydroxide-based flame retardant coated with a silane coupling agent according to the present invention, 0.5 to 2.5 wt% of a methacryloxy-based silane coupling agent is added to magnesium hydroxide. Since the stirring is performed for more than an hour, the yield of the silane coupling agent is improved.
Further, using a magnesium hydroxide having a BET specific surface area of 10 m ² / g or less, an unsaturated fatty acid having 12 or more carbon atoms and at least one of an alkali metal salt and an ammonium salt thereof are used in an amount of 0.1 to 0.1 with respect to magnesium hydroxide. Since 0.5 wt% is added, the water content of the cake is reduced to 50 by filtration and pressing.
% Or less, the handleability can be improved, and the drying cost can be reduced.

Further, the average particle size of magnesium hydroxide is 0.8 to 2.0 μm, and the ratio of particles having a particle size of 0.5 μm or less is 10 v
When the content is ol% or less, it becomes easier to improve the handling properties and mechanical properties.

The magnesium hydroxide-based flame retardant and the flame-retardant resin composition coated with the silane coupling agent of the present invention are easy to produce the flame retardant and have excellent mechanical properties of the resin composition.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuhiro Matsumoto 4-2-7 Koraibashi, Chuo-ku, Osaka-shi F-term in Kamishima Chemical Industry Co., Ltd. (reference) 4H028 AA10 AB02 AB04 BA06 4J002 BB001 BB021 DE076 FB086 FB096 FD136 GT00

Claims (5)

[Claims] (1) a BET specific surface area of 10 m ² / g or less;
The methacryloxy silane coupling agent is used in an amount of 0.2 to 2.0.
wt%, at least one of an unsaturated fatty acid having 12 or more carbon atoms and an alkali metal salt and an ammonium salt thereof is 0.1%.
A magnesium hydroxide-based flame retardant coated with a silane coupling agent comprising magnesium hydroxide, containing 0.5 wt%. 2. The magnesium hydroxide has an average particle size of 0.8 to 2.0 μm and a ratio of magnesium hydroxide particles having a particle size of 0.5 μm or less is 10 vol% or less. A magnesium hydroxide-based flame retardant coated with the silane coupling agent according to the above. 3. An aqueous suspension of magnesium hydroxide having a BET specific surface area of 10 m ² / g or less: 1) 0.5 to 2.5 parts by weight of magnesium hydroxide
% Of a methacryloxy-based silane coupling agent and treated for 10 hours or more. 2) At least one of an unsaturated fatty acid having 12 or more carbon atoms and an alkali metal salt and an ammonium salt thereof is added to the weight of magnesium hydroxide. 3) Then, filtration is carried out so that the water content becomes 50% or less, and 4) drying, wherein the silane coupling agent-coated magnesium hydroxide is added. A method for producing a flame retardant. 4. The silane according to claim 3, wherein the magnesium hydroxide has an average particle size of 0.8 to 2.0 μm and a ratio of particles having a size of 0.5 μm or less is 10 vol% or less. A method for producing a magnesium hydroxide flame retardant coated with a coupling agent. 5. A flame-retardant resin composition comprising the silane coupling agent-coated magnesium hydroxide-based flame retardant according to claim 1 or 2 in an amount of 50 to 300% by weight based on 100% by weight of the polyolefin resin.