KR20190069118A - Method for manufacturing magnesium hydroxide for high strength non-toxic flame-retardant crosslinking compound - Google Patents

Abstract

Provided is a manufacturing method of magnesium hydroxides for a high strength, non-toxic and flame-retardant cross-linking compound. The manufacturing method of the present invention comprises the steps of: mixing high purity magnesium hydroxide powder having 1.0-2.0 μm of average particle size with natural magnesium hydroxide powder having 2.5-3.5 μm of average particle size at a predetermined ratio to prepare a magnesium hydroxide powder mixture, and injecting water to the same to manufacture slurry; after raising the temperature to 80°C or higher, injecting 1.5-2.5 parts by weight of acrylic silane based on 100 parts by weight of the magnesium hydroxide powder mixture to the slurry, and coating magnesium hydroxide powder; and filtering the magnesium hydroxide powder having the acrylic silane coated thereon, and drying the same to manufacture flame-retardant magnesium hydroxides.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a process for preparing magnesium hydroxide for high-strength non-toxic flame retardant crosslinking compounds,

The present invention relates to a process for producing magnesium hydroxide for a high-strength, non-toxic, flame retardant crosslinking compound, and more particularly, to a process for preparing magnesium hydroxide for a crosslinking reaction by using silane as a magnesium hydroxide surface treating agent and controlling the particle characteristics of magnesium hydroxide To a method for producing magnesium hydroxide for a flame retardant compound used in the manufacture of automobiles, power cables and the like.

Generally, the magnesium hydroxide used in the flame retardant compound has different particle characteristics and different kinds of surface treatment agent depending on the required properties. In terms of demand characteristics, compound products in Germany, France and Europe tend to emphasize tensile strength and elongation rate in Asia such as Japan and Korea.

The characteristics of magnesium hydroxide can be defined as follows on the basis of a conventionally known technique. Magnesium hydroxide is used for imparting flame retardancy, and flame resistance evaluation method is vertical flame test and oxygen index measurement.

In order to improve the flame retardancy, the amount of the flame retardant is increased, or bromine or the like is mixed with magnesium hydroxide as an auxiliary flame retardant. However, when the amount of flame retardant is increased, it is difficult to uniformly disperse the resin due to the load increase during the mixing process with the resin. Therefore, it is general to control the flame retardancy by particle size control among the particle characteristics of magnesium hydroxide. In this case, the control of the particle size of magnesium hydroxide is controlled by the use of additives, stirring speed, reaction temperature, reaction time and concentration in salt-alkali reaction.

On the other hand, in the crosslinking compound, the mechanical properties such as tensile strength and elongation are primarily controlled by the particle size, shape or specific surface area, and secondly, the type of silane as the surface treatment agent and the amount of the silane are adjusted. When the magnesium hydroxide particle size is small or the specific surface area is high, the tensile strength tends to increase and the elongation percentage tends to fall, but this also assumes that the resin and dispersibility are uniform. The silane coating agent is mainly composed of vinyl, amino, epoxy, and acrylic, and commonly known vinyl silanes are used in advanced resins.

In addition, the silane-coated magnesium hydroxide-prescribed crosslinked compound can be divided into water-bridge, irradiation-crosslinking and chemical-crosslinking depending on the manufacturing method. It takes the least amount of manufacturing cost, but the quality is 50%. Surveying bridge requires a large-scale surveying equipment at all shipping companies, and it has a disadvantage that it requires a large initial investment, and the degree of bridging is about 70%. Chemical crosslinking is a method of cross-linking at a high temperature of 150 ° C or higher by injecting a chemical crosslinking agent (Dicumyl Peroxide, etc.), which is the most expensive in terms of manufacturing cost, and is not economical.

Power cables, and automobile engine heat-resistant wires, and recently, high strength is required. Silane-coated magnesium hydroxide, widely used in the market today, is a product made by a salt-alkali hydrothermal reaction and has an average particle size of 1.0 to 1.5 μm, a specific surface area of 5.0 to 6.0 m 2 / g, a hexagonal plate structure, a purity of 99.5% And the Fe + Mn content is limited to 100 pmm considering the heat resistance characteristics.

However, when the silane-coated magnesium hydroxide used in the market is used up to now, the tensile strength of the crosslinking compound is limited to 1.5 kgf / cm 2 (100 parts of resin, based on 100 parts of Mg (OH) ₂ ).

Accordingly, it is an object of the present invention to provide magnesium hydroxide capable of obtaining a tensile strength of 1.5 kgf / cm < 2 > or more while maintaining the elongation of the crosslinked compound product.

Further, the technical problems to be solved by the present invention are not limited to the technical problems mentioned above, and other technical problems which are not mentioned can be understood from the following description in order to clearly understand those skilled in the art to which the present invention belongs .

Accordingly, in one aspect of the present invention,

Mixing a high purity magnesium hydroxide powder having an average particle diameter of 1.0 to 2.0 탆 and a natural magnesium hydroxide powder having an average particle diameter of 2.5 to 3.5 탆 at a predetermined ratio to prepare a magnesium hydroxide powder mixture and then adding water thereto to prepare a slurry;

Coating the magnesium hydroxide powder by adding 1.5 to 2.5 parts by weight of acrylic silane based on 100 parts by weight of the magnesium hydroxide powder mixture after raising the slurry to 80 DEG C or higher; And

The present invention also relates to a process for preparing magnesium hydroxide for a high strength non-toxic flame retardant crosslinking compound, which comprises filtering and drying the acrylic silane coated magnesium hydroxide powder to prepare flame-retardant magnesium hydroxide.

The high-purity magnesium hydroxide powder is preferably a powder produced by a hydration reaction.

The mixing ratio of the natural magnesium hydroxide powder to the high purity magnesium hydroxide powder is preferably 10 to 50 wt%.

The drying is preferably performed at 100 to 120 ° C.

The crosslinked compound having the silane-coated magnesium hydroxide prepared by the above-described production process can effectively secure a tensile strength of 1.5 kgf / cm 2 or more.

Hereinafter, the present invention will be described.

Generally, in order to increase the tensile strength of the crosslinked compound product made of magnesium hydroxide, a method of adjusting the type of the silane coating agent, the amount of the particles, the particle size of the magnesium hydroxide, and the specific surface area are adopted.

On the other hand, in the present invention, in order to secure a tensile strength of 1.5 kgf / cm 2 or more of the crosslinked contour foam, a high purity magnesium hydroxide powder having a different particle size and a natural acid magnesium hydroxide powder are mixed and used. In addition, by using hydrophobic acrylic silane as the silane coating agent described above, the problem that magnesium hydroxide coated with vinyl silane in the prior art is vulnerable to moisture and is hardened during long-term storage can be effectively solved.

The method for producing a flame-retardant magnesium hydroxide for a crosslinked contour foam of the present invention comprises mixing a high-purity magnesium hydroxide powder having an average particle size of 1.0 to 2.0 탆 and a natural magnesium hydroxide powder having an average particle size of 2.5 to 3.5 탆 at a predetermined ratio to prepare a magnesium hydroxide powder mixture Preparing a slurry by adding water thereto; Coating the magnesium hydroxide powder by adding 1.5 to 2.5 parts by weight of acrylic silane based on 100 parts by weight of the magnesium hydroxide powder mixture after raising the slurry to 80 DEG C or higher; And filtering the acrylic magnesium silicate-coated magnesium hydroxide powder and drying the acrylic magnesium silicate powder to produce flame-retardant magnesium hydroxide.

First, in the present invention, a high purity magnesium hydroxide powder having an average particle diameter of 1.0 to 2.0 탆 and a natural magnesium hydroxide powder having an average particle diameter of 2.5 to 3.5 탆 are mixed at a predetermined ratio to prepare a magnesium hydroxide powder mixture, .

Particle size of magnesium hydroxide influences flame retardancy and mechanical properties. The smaller the particle size, the better the flame retardancy. The mechanical properties of the non - crosslinked compound increase the tensile strength and decrease the elongation at the non - crosslinked compound, but tend to be opposite in the crosslinked compound.

The present invention corresponds to a crosslinking compound. In order to achieve the object of the present invention, magnesium hydroxide having a larger particle size than that of a product commonly used in the market is required.

Therefore, in the present invention, the magnesium hydroxide powder for a flame retardant is characterized by comprising a high purity magnesium hydroxide powder and a mixed powder of a natural acid magnesium hydroxide powder having an average particle diameter relatively large.

The high purity magnesium hydroxide powder is prepared by the following two methods.

First, the high purity magnesium hydroxide produced by the salt-alkaline hydrothermal reaction is the most excellent in terms of quality, but it is disadvantageous from the viewpoint of productivity because it requires an additional process such as washing for high purity. Since the reaction is high temperature and high pressure, It is uneconomical because it requires additional cost. In order to increase the particle size in the salt-alkali hydrothermal reaction, it is necessary to raise the reaction temperature or to prolong the reaction time. When the reaction temperature is raised, the energy cost of steam is further increased. As the high temperature and high pressure condition becomes severe, the reactor specification becomes higher. In addition, if the reaction time is long, steam or the like is added to the energy to maintain the high temperature condition, and the productivity is decreased. Therefore, although it is possible to manufacture a small amount, it is not applicable in the industrial field.

Second, the magnesium hydroxide produced by the high purity magnesium oxide hydration requires less cost than the salt-alkaline hydrothermal reaction product, but has a disadvantage in that the particles are small in size from the viewpoint of quality, the particles agglomerate strongly, and the specific surface area is large. Because of this, it is not easily applicable to non-crosslinked compound products, but some of them are applied to crosslinking compounds of less flowability. In the above production method, the reaction time may be prolonged such as the use of an additive or a hydrothermal synthesis method in order to increase the particle size. Magnesium salt, acetic acid and the like are used as additives, and the dosage is about 1%. When the reaction time is long, the hydration reaction is carried out at 80 ° C or more. Therefore, the energy cost such as steam and electricity is further added to maintain the temperature, resulting in poor productivity. The hydration reaction has a lower reaction temperature than the salt-alkaline hydrothermal reaction and has a self-exothermic reaction. Therefore, the time required to reach the target temperature is short and the reaction time is less, and the energy cost of steam and the like is low and productivity is good.

As described above, although it is possible to produce a high purity magnesium hydroxide powder having a large particle size, it is disadvantageous from the viewpoints of cost and productivity, and thus, natural magnesium hydroxide hydroxide wool is utilized in the present invention. Natural magnesium hydroxide is a random magnesium oxide powder whose particle shape is not a plate shape by pulverizing water talc to a desired particle size by using a fine grinder such as a jet mill, and the specific surface area is larger than that of the hydrothermal composite. In addition, the purity of the hydrothermal synthesis product or the hydration reaction product is generally 99.5% or more, but the content of the metal component is very high and the whiteness is low. However, there is an advantage in that the particle size can be made larger by adjusting the pulverization method and intensity than the hydrothermal synthesis method or hydration reaction method.

At this time, in the present invention, it is preferable to mix high-purity magnesium hydroxide powder having an average particle diameter of 1.0 to 2.0 m and natural magnesium hydroxide powder having an average particle diameter of 2.5 to 3.5 m.

The mixing ratio of the natural magnesium hydroxide powder to the high purity magnesium hydroxide powder is preferably in the range of 10 to 50% by weight.

Then, water is added to the mixed magnesium hydroxide powder mixture to prepare a slurry. At this time, the concentration of the solid content in the slurry may be about 10%

In the present invention, after the temperature of the slurry is elevated to 80 ° C or higher, 1.5 to 2.5 parts by weight of acrylic silane based on 100 parts by weight of the magnesium hydroxide powder mixture is added to coat the magnesium hydroxide powder.

As the silane coating agent used in the present invention, acrylic system was selected as silane system having only a small number of properties. Although hydrophilic vinyl and amino silanes were studied, the efficiency of filtration by filter press after coating did not come out and troubles occurred in post-process such as drying.

In the present invention, 100 parts by weight of the magnesium hydroxide powder mixture is added to the acrylic silane in the range of 1.5 to 2.5 parts by weight. When the amount of silane added is less than 1.5 parts by weight, the crosslinking property is not exhibited. When the amount of the silane is more than 2.5 parts by weight, the crosslinking property is not increased and the composition is not economical.

On the other hand, the most common use of crosslinked compound products, in which silane-coated magnesium hydroxide is prescribed, is a wire for an automobile engine that generates a lot of heat. Heat resistance is the most important characteristic of flame retardants used in wires without thermal deformation. The amount of the metal component that is commonly known is limited to satisfy the magnesium hydroxide heat resistance. It is known that the metal components such as iron, manganese, nickel, and copper contained in the magnesium hydroxide in the wire are eluted under heat-receiving conditions and cause thermal deformation of the wire. However, according to the results of the present inventors, it has been found that the uniformity of the silane coating is more important than the above-mentioned metal components as the main factors affecting the heat resistance. Therefore, in the present invention, although the amount of the metal component is not limited, only the whiteness of the compound product is minimized.

Subsequently, in the present invention, the magnesium silicate-coated magnesium hydroxide powder is filtered and dried to prepare a flame-retardant magnesium hydroxide. That is, after the coating is completed, it is filtered and dried to obtain a final silane-coated magnesium hydroxide powder.

At this time, in the present invention, the drying temperature is preferably controlled in the range of 100 to 120 ° C. If the temperature is less than 100 ° C, the drying time is long, which is disadvantageous in productivity. If the temperature exceeds 120 ° C, there is a problem that the coated silane on the surface of the magnesium hydroxide particles deforms to damage the coating film.

Hereinafter, the present invention will be described in detail by way of examples.

(Example 1)

 As shown in Table 1 below, magnesium hydroxide having a mean particle diameter of 3.0 占 퐉 obtained by pulverizing magnesium hydroxide having a mean particle size of 1.5 占 퐉 with high purity magnesium hydroxide and a water talc jet mill at a certain ratio [10% (Inventive Example 1), 30 % (Inventive Example 2), 50% (Inventive Example 3)), and water was added thereto to prepare a slurry having a solid content concentration of 10%. At this time, for comparison, powder (Conventional Example 1) made of high purity magnesium hydroxide alone prepared by magnesium oxide hydration reaction and powder made of natural magnesium hydroxide alone (Conventional Example 2) were separately provided, To prepare a slurry having a solid concentration of 10%.

After the 10% magnesium hydroxide slurry was prepared, the acrylic silane was added to 2 parts by weight of magnesium hydroxide (100 parts by weight) after the temperature was raised to 80 ° C or higher, and the coating was carried out for 1 hour. After completion of the coating, the resultant was filtered and dried at 100 to 120 ° C for 24 hours.

On the other hand, the properties of the comparative example 1-2 for the silane-coated high purity magnesium without using the natural magnesium hydroxide powder commercially available in the market were evaluated and also shown in Table 1 below.

division High purity Mg (OH) 2
(Conventional Example 1) Natural acid Mg (OH) 2
(Conventional Example 2) Inventory 1 Inventory 2 Honor Honor 3 Comparative Example 1 Comparative Example 2 Particle size
㎛ 0.6 1.8 0.7 1.0 1.3 0.4 0.5 Average particle diameter
㎛ 1.5 3.0 1.9 2.2 2.4 1.1 1.4 Specific surface value
M 2 / g 5.2 10.8 5.8 6.6 8.1 5.8 5.6 Metal content
ppm Fe 113 1,501 253 520 807 30 24 Mn 10 179 23 65 94 6 One Fe + Mn
+ Cu + Ni 153 1,686 307 632 921 64 77

As shown in Table 1, the natural magnesium hydroxide (Conventional Example 2) has a low manufacturing cost, but the amount of the metal component is about 1500 ppm or more, and when it is prescribed in the crosslinking compound alone, the strength can be increased. However, Can not be used alone because the Fe content is very high. On the other hand, Comparative Example 1-2 using the high purity magnesium hydroxide powder alone has a metal component of 100 ppm or less, which is superior to the conventional Example 2, but has a disadvantage in that it requires a large production cost.

On the contrary, Inventive Example (1-3) of the present invention is a case of mixing a high-purity magnesium hydroxide powder with a high-purity magnesium hydroxide powder, and its properties are somewhat lower than those of Comparative Example 1-2 in terms of metal components, It can be seen that flame-retardant magnesium hydroxide for crosslinked constituent foam can be produced by an economical method because the cost is low.

(Example 2)

A crosslinked compound test article was prepared using the silane-coated Mg (OH) 2 prepared in Example 1-3 of Example 1, and then physical properties were confirmed at room temperature and after aging. The crosslinked compound test articles were prepared in the following order, and the results of the physical property measurement are shown in Table 2 below.

division One 2 3 4 5 6 7 8 9 10 11 12 13 14 combination
Part









Suzy
EVA 100 100 100 100 100 100 100 70 70 70 70 70 70 70 PE 30 30 30 30 30 30 30
Mg (OH) 2



Conventional Example 1 100 100 Conventional Example 2 100 100 Inventory 1 100 100 Inventory 2 100 100 Inventory 3 100 100 Comparative Example 1 100 100 Comparative Example 2 100 100 Antioxidant Irganox 1010 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Cross-linking agent Dicumyl Peroxide 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Properties




Room temperature
The tensile strength 1.38 1.73 1.55 1.64 1.47 1.31 1.26 1.29 1.59 1.47 1.48 1.50 1.23 1.21 Elongation rate 220 160 230 233 247 513 247 190 140 230 200 180 463 177 After Aging
The tensile strength 1.43 1.56 1.60 1.74 1.56 1.18 1.36 1.38 1.33 1.55 1.76 1.72 1.26 1.39 Elongation rate 218 128 220 248 217 474 245 186 120 215 174 179 430 189 Heat resistance
Tensile Residue 104 90 103 106 106 90 108 107 84 105 119 115 102 115 Renal survival rate 99 80 96 106 88 92 99 98 86 93 87 99 93 107 end
correctional Hot / Set 90 /
10 65 /
30 90 /
10 90 /
10 85 /
10 90 /
10 90 /
10 85 /
15 65 /
30 90 /
10 85 /
10 70 /
20 75 /
15 90 /
8

 Crosslinking compound

The resin was mixed with EVA (Ethyl Vinyl Acetate) alone or PE (Poly ethylene). Irganox 1010 as an antioxidant and Dicumyl Peroxide as a crosslinking agent were used. The resin was put into a preheated Keader to dissolve while dispersing. The temperature of Keander was adjusted to 90 ~ 100 ℃ when using EVA alone and 130 ~ 140 ℃ when EVA + PE was mixed.

After dissolving the resin, the silane-coated Mg (OH) 2 sample prepared in Preparation Example 1-2, the antioxidant and the crosslinking agent were added and dispersed for 10 minutes. After completion of the dispersion, the kneaded product was removed from the Keander, and then crosslinked at 180 to 190 ° C for 10 minutes in a heating press.

Heat resistance

The crosslinked compound specimen was naturally cooled in a heating press, and then the specimen was cut into a dumbbell shape with a felt ring. The tensile strength and elongation were measured at room temperature using a universal material testing machine. After aging for 7 days, tensile strength and elongation were measured again at room temperature.

The heat resistance is represented by the tensile residual rate and the elongation percentage, and is determined by the following relational expression 1-2.

[Relation 1]

Tensile residual rate (%) = (tensile strength after Aging / tensile strength before Aging) 占 100

[Relation 2]

Elongation percentage (%) = (elongation after aging / elongation before aging) x 100

Hot-Set Index

The compound crosslinked in the heating press was cut into dumbbell-shaped specimens using a mortar, and then defined as a rate of change in length when the specimen was pulled for 15 minutes under a load of 20 N / cm 2 at a temperature of 200 ° C. After removing the load, The results are shown in Table 2 below, which is defined as a set value of the rate of change in length measured after being left at 200 DEG C and then taken out and cooled at room temperature.

The hot-set value is generally a value indicating the degree of crosslinking. In the present invention, it is normal that the amount of hot-set is about 90% because it is a chemical crosslinking. The hot-set value is obtained by the following Expression 3-4.

[Relation 3]

Hot (%) = 100 - {(length increased / original length) x 100} (200 캜, 20 N / cm 2, 15 min)

[Relation 4]

Set (%) = (length recovered after removal of load / original length) × 100 (200 ° C., 5 minutes)

As shown in Table 2, EVA alone (Examples 1 to 7) was generally used for a power cable. When using natural magnesium hydroxide alone, the tensile strength was very high, but the elongation percentage was the lowest. In addition, when the natural magnesium hydroxide is mixed at 50%, the tensile strength is lowered (Test 5), which appears to be counterproductive even though the particle size is large due to the random shape of the particles.

In EVA + PE formulations (Tests 8 to 14), which are mainly used for automotive wires, magnesium oxide with a large particle size is mixed with H5A silane coating product of Huber Co., Ltd. or KYOWA KISUMA 5P silane coating product, The strength was increased, but the effect was not significant as the mixing amount increased.

On the other hand, as can be seen from the test 1-14 of Table 2, the Hot / Set value decreased as the amount of natural magnesium hydroxide used increased. In case of using only natural magnesium hydroxide with a large particle size, it can not satisfy the general management range of Hot 70% or more and set 10% or less. This seems to be caused by the fact that the metal component contained in the magnesium hydroxide is eluted under the condition of receiving heat and weakening the cross-linking force between the resin and magnesium hydroxide.

While the present invention has been particularly shown and described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of course, this is possible. Therefore, the scope of the present invention should not be limited to the above-described embodiments but should be defined by the following claims as well as equivalents thereof.

Claims (4)

Mixing a high purity magnesium hydroxide powder having an average particle diameter of 1.0 to 2.0 탆 and a natural magnesium hydroxide powder having an average particle diameter of 2.5 to 3.5 탆 at a predetermined ratio to prepare a magnesium hydroxide powder mixture and then adding water thereto to prepare a slurry;
Coating the magnesium hydroxide powder by adding 1.5 to 2.5 parts by weight of acrylic silane based on 100 parts by weight of the magnesium hydroxide powder mixture after raising the slurry to 80 DEG C or higher; And
A method for preparing magnesium hydroxide for a high-strength, non-toxic, flame-retardant crosslinking compound, comprising the steps of: (1) filtering magnesium hydroxide powder coated with acrylic silane and then drying to obtain flame-retardant magnesium hydroxide;
The method of claim 1, wherein the high purity magnesium hydroxide powder is a powder prepared by a magnesium hydration reaction.
The method of claim 1, wherein the mixing ratio of the natural magnesium hydroxide powder to the high purity magnesium hydroxide powder is 10 to 50 wt%.
The method of claim 1, wherein the drying is performed at 100 to 120 ° C.