KR100379098B1 - Polypropylene-coated magnesium hydroxide, method for preparing thereof and flame retardant composite polypropylene comprising the same - Google Patents

Abstract

The present invention relates to magnesium hydroxide coated with polypropylene, a method for preparing the same, and a flame-retardant composite polypropylene including the same, and more specifically, (i) drying magnesium hydroxide under a nitrogen atmosphere; (ii) stirring the dried magnesium hydroxide with a solvent in a reactor at room temperature substituted with a nitrogen atmosphere; (iii) raising the temperature of the reactor to 80 to 100 ° C., and then adding titanium halide and reacting; (iv) cooling the reaction mixture to room temperature, followed by washing and drying to obtain titanium hydroxide loaded with titanium; (v) adding titanium hydroxide-supported magnesium hydroxide, alkyl aluminum and hexane to the reactor, and then continuously adding propylene while stirring to perform hexane slurry propylene polymerization; And (vi) filtering the hexane slurry on which the polymerization reaction is completed to remove hexane and drying to obtain magnesium hydroxide powder coated with polypropylene. Magnesium hydroxide coated with polypropylene and a flame retardant composite polypropylene comprising the same, the polypropylene coated magnesium hydroxide prepared according to the method of the present invention is uniformly dispersed when mixed with a polypropylene resin, flame retardant, bending It provides a flame retardant composite polypropylene having excellent strength and Izod impact strength.

Description

Polypropylene-coated magnesium hydroxide, method for preparing coconut and flame retardant composite polypropylene comprising the same}

The present invention relates to magnesium hydroxide coated with polypropylene, a method for preparing the same, and a flame-retardant composite polypropylene including the same, and more specifically, (i) drying magnesium hydroxide under a nitrogen atmosphere; (ii) stirring the dried magnesium hydroxide with a solvent in a reactor at room temperature substituted with a nitrogen atmosphere; (iii) raising the temperature of the reactor to 80 to 100 ° C., and then adding titanium halide and reacting; (iv) cooling the reaction mixture to room temperature, followed by washing and drying to obtain titanium hydroxide loaded with titanium; (v) adding titanium hydroxide-supported magnesium hydroxide, alkyl aluminum and hexane to the reactor, and then continuously adding propylene while stirring to perform hexane slurry propylene polymerization; And (vi) filtering the hexane slurry on which the polymerization reaction is completed to remove hexane and drying to obtain magnesium hydroxide powder coated with polypropylene. Magnesium hydroxide coated with polypropylene and a flame retardant composite polypropylene comprising the same.

In general, flame-retardant composite polypropylene is prepared by compounding a polypropylene resin and a flame retardant such as an organic halogen compound or antimony oxide (Sb ₂ O ₃ ) together. However, the flame-retardant composite polypropylene thus prepared has a serious problem of generating corrosive and toxic gases during molding and generating toxic gases in fire.

Therefore, in recent years, efforts have been actively made to manufacture flame retardant composite polypropylene using aluminum hydroxide (Al ₂ (OH) ₃ ) and magnesium hydroxide (Mg (OH) ₂ ) as flame retardants. When aluminum hydroxide or magnesium hydroxide is used as the flame retardant, not only the generation of toxic gas by the flame retardant during molding but also the advantage of reducing the amount of combustion gas upon combustion of the flame retardant.

However, aluminum hydroxide has a disadvantage in that dehydration reaction starts at 180 ° C., so that it is unstable at 200 ° C., which is a processing temperature range of a general polypropylene, and thus cannot perform its function properly.

On the other hand, magnesium hydroxide is stable at a processing temperature range of polypropylene because the start temperature of the dehydration reaction is 340 ° C, and is known as a flame retardant most suitable for producing a flame retardant composite polypropylene. However, magnesium hydroxide has a disadvantage in that it is difficult to evenly disperse the polypropylene resin because small crystals are easily entangled with each other and incompatible with polypropylene. Therefore, it should be added in a large amount of about 60% by weight relative to the total composition, as a result of the problem that the degradation of the tensile strength and impact properties of the product is severe.

In an effort to solve this problem, Japan's flame retardant manufacturer Kyowa Chemical compounded magnesium hydroxide coated with sodium stearate with polypropylene to produce a flame retardant composite polypropylene, and the flame retardant composite polypropylene is coated Almost the only example reported is excellent flexural strength and Izod impact strength, while maintaining comparable flame retardancy compared to the use of non-magnesium hydroxide (see J. Appl. Poly. Sci ., 25 (1980). 415).

Therefore, there is an urgent need to develop a flame retardant having improved compatibility with polypropylene.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art as described above. After supporting titanium as a propylene polymerization catalyst component on magnesium hydroxide, it is polymerized with propylene in the presence of magnesium hydroxide on which titanium is supported and coated with polypropylene. It is to provide a method for producing magnesium hydroxide.

Another object of the present invention is to provide magnesium hydroxide coated with polypropylene produced by the above method.

Still another object of the present invention is to provide a flame retardant composite polypropylene comprising magnesium hydroxide coated with the polypropylene as a flame retardant.

That is, one aspect of the present invention

(i) drying magnesium hydroxide under a nitrogen atmosphere;

(ii) stirring the dried magnesium hydroxide with a solvent in a reactor at room temperature substituted with a nitrogen atmosphere;

(iii) raising the temperature of the reactor to 80 to 100 ° C., and then adding titanium halide and reacting;

(iv) cooling the reaction mixture to room temperature, followed by washing and drying to obtain titanium hydroxide loaded with titanium;

(v) adding titanium hydroxide-supported magnesium hydroxide, alkyl aluminum and hexane to the reactor, and then continuously adding propylene while stirring to perform hexane slurry propylene polymerization; And

(vi) filtering the hexane slurry of the completion of the polymerization reaction to remove hexane and drying to obtain a magnesium hydroxide powder coated with polypropylene to provide a method for producing polypropylene coated magnesium hydroxide.

Another aspect of the present invention provides magnesium hydroxide coated with polypropylene produced by the above method.

Another aspect of the present invention provides a flame retardant composite polypropylene comprising 5 to 80% by weight of magnesium hydroxide and 20 to 95% by weight of polypropylene resin coated with the polypropylene.

Hereinafter, the present invention will be described in more detail.

In the method for producing polypropylene coated magnesium hydroxide of the present invention, after supporting titanium which can act as a catalyst during propylene polymerization on magnesium hydroxide, the titanium hydroxide obtained therefrom (hereinafter referred to as "titanium-supported magnesium hydroxide") And a step of coating the titanium-supported magnesium hydroxide with polypropylene by carrying out a hexane slurry propylene polymerization in the presence of an alkyl aluminum promoter, and a method of preparing magnesium hydroxide coated with polypropylene of the present invention. It will be described in detail as follows.

First, the magnesium hydroxide is dried at a high temperature in a nitrogen atmosphere to remove moisture and oxygen contained in the magnesium hydroxide, and then stirred together with a solvent such as toluene in a reactor at room temperature substituted with a nitrogen atmosphere. Subsequently, after raising the temperature of the reactor to 80 to 100 ° C, titanium halide is added and reacted. The reaction time is suitably 1 hour to 2 hours. It is preferable to use TiCl ₄ as the titanium halide. In this case, titanium-supported magnesium hydroxide is produced by the following reaction formula (1).

Mg-OH + TiCl ₄ → Mg-O-TiCl ₃ + HCl

After the reaction is completed, the reaction mixture is cooled to room temperature, washed and dried to obtain titanium-supported magnesium hydroxide. In the washing process, it is preferable to first wash with toluene, and then again with hexane.

Subsequently, hexane was added to a high pressure polymerization reactor substituted with a nitrogen atmosphere, and alkyl aluminum, preferably triethyl aluminum, which could serve as a co-catalyst in the polymerization of titanium-supported magnesium hydroxide and propylene obtained above was added, and then After raising the temperature to 60 to 80 ° C, the polymerization reaction is continued while propylene is added so that the stirring is started and the pressure in the reactor is maintained at 2 to 7 atm. After the polymerization reaction is complete, the hexane slurry is cooled and then filtered to remove hexane and dried to obtain magnesium hydroxide coated with polypropylene in powder form.

The magnesium hydroxide coated with the polypropylene of the present invention prepared as described above contains 1 to 20% by weight of polypropylene.

The flame-retardant composite polypropylene of the present invention is prepared by compounding 5 to 80% by weight of magnesium hydroxide and 20 to 95% by weight of pellet-type polypropylene coated with polypropylene obtained above with a blender. If the content of magnesium hydroxide coated with polypropylene is less than 5% by weight or more than 80% by weight, the object of the present invention cannot be achieved.

Hereinafter, the present invention will be described in more detail with reference to examples, but these examples are for illustrative purposes only and should not be construed as limiting the present invention.

Preparation Example 1

Magnesium hydroxide was dried at 120 ° C. while purging nitrogen to remove moisture and oxygen. 5L of toluene was added to a 10L reactor replaced with a nitrogen atmosphere, and 800 g (13.6 mol) of the dried magnesium hydroxide was added thereto, followed by stirring at 300 rpm at room temperature. After sufficient stirring, the temperature of the reactor was raised to 88 ° C. over 1 hour, and then 38.4 ml (0.32 mol) of TiCl ₄ was added and reacted for 1 hour so that titanium was supported on magnesium hydroxide. After cooling the temperature of the reaction mixture to room temperature, the mixture was washed sequentially with toluene and hexane and dried to obtain titanium-supported magnesium hydroxide.

Subsequently, 1 L of hexane was added to a 2 L high pressure polymerization reactor (Parr, Model # 5422) substituted with a nitrogen atmosphere, and 200 g of titanium-supported magnesium hydroxide obtained above and 80 mmol of triethyl aluminum as a promoter were added thereto. After the temperature of the polymerization reactor was raised to 70 ° C., the polymerization reaction was performed for 1 hour while continuously adding propylene so as to start stirring and maintain the pressure in the reactor at 7 atm. After the reaction was completed, stirring was stopped, the temperature was lowered, and then the hexane slurry was filtered to remove hexane and dried to obtain magnesium hydroxide coated with polypropylene on powder.

TGA analysis confirmed that the polypropylene content of the magnesium hydroxide coated with the polypropylene thus prepared was 13% by weight.

Preparation Example 2

Magnesium hydroxide coated with polypropylene was prepared in the same manner as in Preparation Example 1, except that the polymerization reaction was performed for 40 minutes. TGA analysis confirmed that the polypropylene content of the magnesium hydroxide coated with the polypropylene thus prepared was 7% by weight.

Preparation Example 3

Magnesium hydroxide coated with polypropylene was prepared in the same manner as in Preparation Example 1, except that the pressure in the polymerization reactor was maintained at 2 atmospheres. TGA analysis confirmed that the polypropylene content of the magnesium hydroxide coated with the polypropylene thus prepared was 3% by weight.

Example 1

Compounding 69 g of magnesium hydroxide coated with polypropylene obtained from Preparation Example 1 and 31 g of polypropylene pellet (Samsung General Chemical, HI700) in a small mixer so that the magnesium hydroxide content in the final flame retardant composite polypropylene was about 60% by weight. To prepare a flame retardant composite polypropylene.

After compression molding the flame-retardant composite polypropylene thus prepared to produce a sheet of 2mm thickness, the physical properties were evaluated and the results are shown in Table 1 below.

Example 2

64.5 g of polypropylene coated with polypropylene obtained from Preparation Example 2 and 35.5 g of polypropylene pellets (Samsung General Chemical, HI700) were obtained in a small mixer so that the magnesium hydroxide content in the final flame retardant composite polypropylene was about 60% by weight. Compounding to prepare a flame retardant composite polypropylene.

After compression molding the flame-retardant composite polypropylene thus prepared to produce a sheet of 2mm thickness, the physical properties were evaluated and the results are shown in Table 1 below.

Example 3

In a small mixer, 61.9 g of magnesium hydroxide coated with polypropylene obtained from Preparation Example 3 and 38.1 g of polypropylene pellet (Samsung General Chemical, HI700) were obtained in a small mixer so that the magnesium hydroxide content in the final flame retardant composite polypropylene was about 60% by weight. Compounding to prepare a flame retardant composite polypropylene.

After compression molding the flame-retardant composite polypropylene thus prepared to produce a sheet of 2mm thickness, the physical properties were evaluated and the results are shown in Table 1 below.

Comparative example

Flame retardant composite polypropylene was prepared by compounding 60 g of pure magnesium hydroxide and 40 g of polypropylene pellet (Samsung General Chemical, HI700) dried at 120 ° C. for 4 hours in a nitrogen atmosphere.

After compression molding the flame-retardant composite polypropylene thus prepared to produce a sheet of 2mm thickness, the physical properties were evaluated and the results are shown in Table 1 below.

Flexural Strength (Kg / ㎠) Impact Strength (Kg / ㎠) Flame Retardant Grade Example 1 26060 9.5 V0 Example 2 24400 8 VO Example 3 23600 7 V0 Comparative example 22750 7 V0

[Property evaluation method]

* Flexural Strength: ASTM D790

* Impact Strength: ASTM D256

* Flame retardant grade: UL 94

As can be seen from Table 1, the flame retardant composite polypropylene prepared using the magnesium hydroxide coated with the polypropylene of the present invention, while maintaining a flame retardant grade equivalent to the conventional flame retardant composite polypropylene including pure magnesium hydroxide, The flexural strength was excellent and the impact strength was also slightly improved.

As described in detail above, magnesium hydroxide coated with polypropylene prepared according to the method of the present invention has high compatibility with polypropylene and is uniformly dispersed when mixed with polypropylene resin, so that flame retardancy, flexural strength and Izod impact strength are increased. Provides excellent flame retardant composite polypropylene.

Claims (9)

(i) drying magnesium hydroxide under a nitrogen atmosphere; (ii) stirring the dried magnesium hydroxide with a solvent in a reactor at room temperature substituted with a nitrogen atmosphere; (iii) raising the temperature of the reactor to 80 to 100 ° C., and then adding titanium halide and reacting; (iv) cooling the reaction mixture to room temperature, followed by washing and drying to obtain titanium hydroxide loaded with titanium; (v) adding titanium hydroxide-supported magnesium hydroxide, alkyl aluminum and hexane to the reactor, and then continuously adding propylene while stirring to perform hexane slurry propylene polymerization; And (vi) a method for producing polypropylene-coated magnesium hydroxide, comprising the step of filtering the completed hexane slurry to remove hexane and drying to obtain magnesium hydroxide powder coated with polypropylene. The method of claim 1, Method of producing magnesium hydroxide coated with polypropylene, characterized in that toluene is used as a solvent in the step (ii). The method of claim 1, Method of producing a polypropylene-coated magnesium hydroxide, characterized in that using TiCl ₄ as titanium halide in the step (iii). The method of claim 1, Process for producing a polypropylene-coated magnesium hydroxide, characterized in that the reaction is carried out for 1 to 2 hours in the step (iii). The method of claim 1, Method of producing a polypropylene-coated magnesium hydroxide, characterized in that the washing with toluene and then again with hexane in the washing step (iv). The method of claim 1, Method for producing a polypropylene-coated magnesium hydroxide, characterized in that the polymerization in the step (v) is carried out under the conditions of 60 to 80 ℃, 2 to 7 atm. Magnesium hydroxide coated with polypropylene prepared by the method of claim 1. The method of claim 7, wherein Magnesium hydroxide coated with polypropylene, characterized in that the polypropylene content is 1 to 20% by weight. Flame-retardant composite polypropylene comprising 5 to 80% by weight of magnesium hydroxide and 20 to 95% by weight of polypropylene resin coated with the polypropylene of claim 7.