KR102180931B1 - Graphene oxide filler with aminated flame retardant, and polypropylene nanocomposite using the same - Google Patents

Abstract

The present invention relates to a graphene oxide filler, and to a graphene oxide including a compatibilizer and a flame retardant and a method for preparing the same. In particular, the flame retardant is bonded to a functional group present on the surface or edge of the graphene oxide, and the compatibilizer is a filler, characterized in that it is bonded to the graphene oxide or the flame retardant, excellent compatibility with the base polymer And due to the dispersibility, it is possible to reduce the amount of filler added to improve the physical properties of the base polymer.
In addition, the present invention relates to a flame-retardant polypropylene composition comprising the graphene oxide filler and a method for manufacturing the same, and provides a flame-retardant polypropylene composition having excellent flame retardancy and mechanical properties compared to conventional polypropylene through the graphene oxide filler. Can be obtained.

Description

Graphene oxide filler modified with aminated flame retardant and polypropylene nanocomposite composition using the same {GRAPHENE OXIDE FILLER WITH AMINATED FLAME RETARDANT, AND POLYPROPYLENE NANOCOMPOSITE USING THE SAME}

The present invention relates to a graphene oxide filler, and in particular, to a graphene oxide modified with a compatibilizer and a flame retardant, and a method for preparing the same.

In addition, the present invention relates to a flame-retardant polypropylene composition comprising a graphene oxide filler and a method for producing the same, and through the filler, a polypropylene composite material having excellent flame retardancy and mechanical properties compared to conventional polypropylene can be obtained.

The flame retardant polypropylene composition of the present invention can be used in the final finished product industries such as construction, automobile, electronics, furniture, packaging, and the like.

Polypropylene, which is widely used as a general-purpose resin, is used in various fields such as everyday home appliances, building materials, and automotive materials. However, as polypropylene is a combustible material, a plan is needed to prevent the risk of fire.

Commonly used flame retardants include halogen-based flame retardants, inorganic flame retardants, and phosphorus-based flame retardants. Halogen-based flame retardants are the most widely used flame retardants because of their excellent flame retardancy. However, since toxic gas is generated during combustion, which causes fatal problems to the environment and human body, its use is prohibited. On the other hand, inorganic flame retardants do not contain halogen and are non-toxic, but inorganic flame retardants require the addition of 30% by weight or more, and the addition of such a high content flame retardant increases the viscosity of the base polymer, lowering processability, and adversely affecting mechanical properties. There is a problem. Phosphorus-based flame retardants are also flame retardants that can solve environmental and human hazard problems, but there is a problem that mechanical properties are deteriorated when added to the base polymer, so a plan to compensate for this is required.

On the other hand, graphene is one of carbon allotropes such as graphite, fullerene, and carbon nanotubes composed of only carbon atoms. Graphene is characterized by the fact that one carbon atom has a sp ² covalent bond with three carbon atoms and has a two-dimensional plate-like structure. Graphene has excellent electrical, thermal, and mechanical properties due to a two-dimensional plate structure, but pure graphene has a problem of low compatibility when mixed with a polymer resin. Meanwhile, as graphene that has undergone an oxidation process, graphene oxide is a material that can be easily modified through a secondary chemical reaction because various functional groups exist on the surface.

Research has been actively conducted to improve the physical properties of polymer composite materials using such graphene and graphene oxide, and there are attempts to introduce flame retardants into graphene. Korean Patent No. 1665680 relates to a flame retardant containing graphene oxide doped with a phosphorus component, and the surface of graphene oxide is modified through phosphoric acid or polyphosphoric acid. In addition, Chinese Laid-Open Patent No. 107325324 relates to a flame-retardant antistatic polypropylene foam bead, in which phosphine oxide and graphene carbon nanofibers are added to a thermoplastic resin to impart flame retardancy.

However, when graphene oxide modified only with a flame retardant as described above is added to a polymer resin, its compatibility is low, dispersibility is poor, and a high content of graphene is required, which may adversely affect the physical properties of the polymer composite material. Therefore, it is required to develop a filler capable of imparting excellent flame retardancy to the matrix material even with a small amount of addition and improving mechanical properties.

Korean Patent No. 1665680 (registered on Oct. 6, 2016) Chinese Patent Publication No. 107325324 (published on November 7, 2017)

The graphene oxide filler of the present invention was devised to solve the above problems, and an object thereof is to provide a graphene oxide filler including a flame retardant and a compatibilizer, and a method of manufacturing the same.

In addition, another object of the present invention is to provide a flame-retardant polypropylene composition comprising polypropylene and the graphene oxide filler, and a method of manufacturing the same.

The present invention can also aim to achieve these objects and other objects that can be easily derived by a person skilled in the art from the general description of the present specification, in addition to the above-described clear objects.

Graphene oxide filler of the present invention in order to achieve the object as described above,

100 parts by weight of graphene oxide modified with a flame retardant, and

20 to 1000 parts by weight of a compatibilizer, preferably 80 to 800 parts by weight, more preferably 100 to 500 parts by weight,

The flame retardant is bonded to a functional group present on the surface or edge of the graphene oxide,

The compatibilizer is characterized in that it is bound to the graphene oxide or the flame retardant.

In addition, the compatibilizer may be characterized in that it is a reactive compatibilizer.

In addition, the compatibilizer is preferably polypropylene grafted with maleic anhydride or polyethylene grafted with maleic anhydride.

In addition, the flame retardant may be characterized in that it is a phosphorus-based flame retardant having an amine group.

In addition, the flame retardant is a phosphate-based flame retardant, a phosphonate-based flame retardant, a phosphinate-based flame retardant, a phosphazene-based flame retardant, a melamine phosphate-based flame retardant, an ammonium polyphosphate-based flame retardant, an ammonium phosphinate-based flame retardant, a phosphophenanthrene-based flame retardant. , It may be selected from the group consisting of a phosphine oxide-based flame retardant and a mixture thereof.

Further, the flame retardant may be an aminated triphenylene phosphine oxide.

In addition, the graphene oxide modified with the flame retardant,

Graphene oxide 35 to 65% by weight, preferably 40 to 60% by weight, more preferably 45 to 55% by weight, and

It is characterized in that it contains 35 to 65% by weight of the flame retardant, preferably 40 to 60% by weight, more preferably 45 to 55% by weight.

On the other hand, the manufacturing method of the graphene oxide filler of the present invention,

(A) forming an amine group (-NH ₂ ) in the aromatic phosphorus-based flame retardant;

(B) dispersing graphene oxide in a solvent and performing ultrasonic treatment;

(C) modifying graphene oxide with a flame retardant by adding a flame retardant in which the amine group is formed to the graphene oxide solution; And

(D) mixing the graphene oxide modified with the flame retardant with a compatibilizer to introduce the compatibilizer to the graphene oxide; characterized by comprising a.

In addition, the aromatic flame retardant may be an aromatic phosphorus-based flame retardant.

In addition, the aromatic flame retardant is preferably triphenylene phosphine oxide (triphenylene phosphine oxide).

And, it is preferable that the compatibilizer is polypropylene grafted with maleic anhydride.

In addition, the solvent may be tetrahydrofuran.

In addition, the step A,

(a) forming a nitro group (-NO ₂ ) in the aromatic flame retardant; And

(b) reducing the aromatic flame retardant in which the nitro group is formed; may be characterized by including.

And, the step a,

100 parts by weight of an aromatic flame retardant, and

Nitric acid 200 to 800 parts by weight, preferably 250 to 600 parts by weight, more preferably 300 to 500 parts by weight may be characterized by mixing.

In addition, step a may be characterized in that the reaction temperature is maintained at 18 to 40°C, preferably at 20 to 35°C, and more preferably at 22 to 30°C.

In addition, the step a may be characterized in that the reaction time is 2 to 7 hours, preferably 3 to 6 hours, more preferably 4 to 5 hours.

In addition, after step a and before step b, the product of step a is added to ice water for extraction, and filtering may be further included.

In addition, the step b,

100 parts by weight of the flame retardant formed with the nitro group, and

SnCl ₂ (Tin(II)chloride) 200 to 1000 parts by weight, preferably 300 to 900 parts by weight, more preferably 400 to 800 parts by weight, may be characterized by mixing.

In addition, the step b,

100 parts by weight of hydrochloric acid, and

100 to 400 parts by weight of ethanol, preferably 150 to 300 parts by weight, more preferably 180 to 250 parts by weight, may be further added.

In addition, the step b,

It may be characterized by maintaining the reaction temperature at 18 to 40°C, preferably at 20 to 35°C, and more preferably at 22 to 30°C.

In addition, step b may be characterized in that the reaction time is 2 to 8 hours, preferably 3 to 7 hours, and more preferably 4 to 6 hours.

And, it may be characterized in that it further comprises the step of extracting and filtering the product of step B through sodium hydroxide after step A and before step B.

In addition, the step C may be characterized in that the reaction temperature is maintained at 40 to 100 ℃, preferably 50 to 90 ℃, more preferably 60 to 80 ℃.

In addition, the step C may be characterized in that the reaction time is 3 to 10 hours, preferably 4 to 9 hours, more preferably 5 to 8 hours.

In addition, after step C and before step D, filtering the product of step C through filtering and washing with a solvent may be further included.

In addition, the step D may be characterized in that the reaction temperature is maintained at 100 to 300 °C, preferably 150 to 250 °C, more preferably 170 to 220 °C.

In addition, the step D may be characterized in that the reaction time is 2 to 16 minutes, preferably 4 to 12 minutes, more preferably 6 to 10 minutes.

In addition, the step D may be characterized in that a mixer is used, and a rotational speed of the mixer is 30 to 120 rpm, preferably 40 to 100 rpm, more preferably 50 to 80 rpm.

On the other hand, the flame retardant polypropylene composition of the present invention,

76 to 98% by weight of polypropylene, preferably 79 to 95% by weight, more preferably 82 to 94% by weight, and

The graphene oxide filler is characterized in that it comprises 2 to 24% by weight, preferably 5 to 21% by weight, more preferably 6 to 18% by weight.

In addition, the flame-retardant polypropylene composition is preferably prepared by melt-mixing the graphene oxide filler and polypropylene.

And, the melt mixing is mixed using an extruder, and the rotation speed of the extruder may be characterized in that 50 to 500 rpm, preferably 100 to 400 rpm, more preferably 150 to 300 rpm.

In addition, the melt mixing may be characterized in that the reaction temperature is maintained at 80 to 300 °C, preferably 100 to 250 °C, more preferably 160 to 220 °C.

And, the flame retardant index may be 7 to 25, preferably 10 to 20, more preferably 12 to 17.

The graphene oxide filler according to the present invention is graphene oxide whose surface is modified with a flame retardant and has flame retardancy, and has excellent dispersibility due to excellent compatibility with the base polymer because the surface is modified with a compatibilizer.

In addition, the graphene oxide filler of the present invention is prepared by introducing a modified flame retardant formed with an amine group, and a large amount of the flame retardant can be attached to the surface of the graphene oxide.

On the other hand, the flame retardant polypropylene composition according to the present invention is a polypropylene containing the graphene oxide filler, has flame retardancy due to the flame retardant of the filler, and in particular, when using a phosphorus-based flame retardant, also solves the toxicity problem to the human body and the environment due to the flame retardant I can.

In addition, since the flame-retardant polypropylene composition of the present invention includes a filler having excellent compatibility and dispersibility, mechanical properties can be improved only by adding a small amount of the filler, and has particularly excellent tensile modulus and tensile strength. Through this, it is possible to improve the problem of reducing processability and mechanical properties of the composite material due to the addition of a high content filler, which has been a problem in the prior art.

On the other hand, the graphene oxide filler of the present invention, which has an excellent effect on improving the performance of composite materials, is not limited to a filler for polypropylene, and is expected to be applied in various fields such as automobile materials and construction materials.

1 shows a method of preparing graphene oxide modified with a flame retardant as an embodiment according to the present invention.
2 is an infrared spectral spectrum of graphene oxide modified with aminated TPPO prepared according to the present invention.
3 is an X-ray photoelectron spectral spectrum of graphene oxide modified with aminated TPPO prepared according to the present invention.
4 is a graph showing the limiting oxygen index of the polypropylene composition prepared according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail.

However, the following is only for describing in detail by exemplifying specific embodiments, and since the present invention may be variously changed and may have various forms, the present invention is not limited to the illustrated specific embodiments. It is to be understood that the present invention includes all changes, equivalents, and substitutes included in the spirit and scope of the present invention.

In addition, in the following description, there are many specific matters such as specific elements, etc., which are provided only to help a more general understanding of the present invention, and the present invention can be practiced without these specific matters. It is self-evident to those who have the knowledge of Further, in describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In addition, terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Unless otherwise defined, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms as defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in this application. Does not.

In this application, expressions in the singular include plural expressions unless the context clearly indicates otherwise.

In the present application, terms such as'include','include', or'have' are intended to refer to the presence of features, elements (or constituents), etc. described in the specification, but one or more other features or It does not mean that the component or the like does not exist or cannot be added.

In this application, the'flame retardant index' is defined by the following formula:

Flame retardant index = (flame retardant reaction time / compatibilizer reaction time)

× (compatibilizer mixing rpm / resin mixing rpm).

The present invention relates to a graphene oxide filler, including graphene oxide and a compatibilizer modified with a flame retardant, the flame retardant is bonded to a functional group present on the surface or edge of the graphene oxide, and the compatibilizer is the It is characterized in that it is bonded to graphene oxide or the flame retardant.

The graphene oxide filler refers to that the surface of the graphene oxide is modified by combining graphene oxide with a flame retardant and a compatibilizer. Graphene oxide has a plate-like structure and has various functional groups on its surface, and the functional groups refer to various oxygen functional groups such as a carboxyl group, a carbonyl group, a hydroxy group, and an epoxy group. Such a functional group may react with a functional group of a flame retardant and a compatibilizer or a non-shared electron pair to form a covalent bond, and as a result, a graphene oxide filler in which a flame retardant and a compatibilizer are present in a large amount on the graphene oxide surface may be formed.

The graphene oxide filler may include 20 to 1000 parts by weight of a compatibilizer, preferably 80 to 800 parts by weight, more preferably 100 to 500 parts by weight, based on 100 parts by weight of graphene oxide modified with a flame retardant. When the content of the compatibilizer is less than the above range, the dispersibility of the filler is deteriorated because the role of the compatibilizer does not sufficiently function, and when it exceeds the above range, the physical properties of the composite material may be adversely affected by the compatibilizer.

A compatibilizer is a compound that serves to impart compatibility between different raw materials, and the compatibilizer of the present invention may be a reactive compatibilizer, and a person skilled in the art may adopt an appropriate compatibilizer. In particular, when using maleic anhydride grafted polypropylene (MAPP) or maleic anhydride grafted polyethylene (MAPE) as a compatibilizer, graphene oxide fillers having excellent dispersibility are used. Can be obtained.

Further, the flame retardant may be a halogen-based flame retardant or a non-halogen-based flame retardant, but it is preferable to use a phosphorus-based flame retardant capable of preventing the generation of gases harmful to the human body and the environment. In this aspect, the flame retardant is a phosphate-based flame retardant, a phosphonate-based flame retardant, a phosphinate-based flame retardant, a phosphazene-based flame retardant, a melamine phosphate-based flame retardant, an ammonium polyphosphate-based flame retardant, an ammonium phosphinate-based flame retardant, a phosphophenanthrene-based It may be selected from the group consisting of a flame retardant, a phosphine oxide-based flame retardant, and a mixture thereof, but is not limited thereto.

In addition, the flame retardant may be a phosphorus-based flame retardant having an amine group, and if it has an amine group, it is easy to react with a functional group present on the surface or edge of the graphene oxide, and in particular, it may react with an epoxy group and a carboxyl group to form a bond. Therefore, it is possible to attach as many flame retardants as possible to the surface or edge of the graphene oxide, and when added to the polymer, the flame retardancy of the polymer as a matrix material can be maximized even with a small amount of graphene oxide filler. Accordingly, it is possible to prevent the problem of deterioration in processability and mechanical properties of the matrix material due to the addition of a large amount of graphene oxide filler.

The phosphorus-based flame retardant having an amine group may be graphene oxide modified with aminated triphenylene phosphine oxide (ATPPO), and when the material is introduced, excellent flame retardancy may be exhibited.

In addition, the graphene oxide modified with the flame retardant of the present invention, graphene oxide 35 to 65 wt%, preferably 40 to 60 wt%, more preferably 45 to 55 wt%, and a flame retardant 35 to 65 wt%, It may include preferably 40 to 60% by weight, more preferably 45 to 55% by weight, and may exhibit sufficient flame retardancy within the above weight% range.

As a method of evaluating flame retardancy, the Limiting Oxygen Index (LOI) can be measured. The limiting oxygen index is the minimum oxygen concentration required to sustain the combustion of a sample, and the larger the limiting oxygen index, the better the flame retardancy. Since the oxygen concentration in the mixed air containing nitrogen is about 20%, a material having an oxygen index of 20 or less can be regarded as a material that is easily combusted.

On the other hand, the manufacturing method of the graphene oxide filler of the present invention,

(A) forming an amine group (-NH ₂ ) in the aromatic flame retardant;

(B) dispersing graphene oxide in a solvent and performing ultrasonic treatment;

(C) modifying graphene oxide with a flame retardant by adding a flame retardant in which the amine group is formed to the graphene oxide solution; And

(D) mixing the graphene oxide modified with the flame retardant with a compatibilizer to introduce the compatibilizer to the graphene oxide; characterized by comprising a.

The aromatic flame retardant is preferably a phosphorus flame retardant that is a non-halogen flame retardant, and may be triphenylene phosphine oxide (TPPO). This is because when an amine group is formed in the triphenylene phosphine oxide, the amine group of the triphenylene phosphine oxide can react well with a functional group present on the surface or edge of the graphene oxide. In particular, the amine group can be reacted with both the epoxy group and the carboxy group of the graphene oxide, so that a large amount can be attached to the graphene oxide, and the reaction can easily occur even with a compatibilizer, making it easy to manufacture.

In addition, the compatibilizer is preferably a reactive compatibilizer, and in particular, when using maleic anhydride grafted polypropylene (MAPP) or maleic anhydride grafted polyethylene (MAPE), polypropylene It can exhibit excellent compatibility with.

In the step of forming an amine group in the aromatic flame retardant, various amination reactions for forming an amine group in the aromatic compound may be used, and in particular, the nitration reaction and the reduction reaction may be sequentially performed to form an amine group. Accordingly, the step A,

(a) forming a nitro group (-NO ₂ ) in the aromatic flame retardant; And

(b) reducing the aromatic flame retardant in which the nitro group is formed; may be characterized by including.

In the step of forming a nitro group in the aromatic flame retardant, 100 parts by weight of the aromatic flame retardant, and 200 to 800 parts by weight of nitric acid, preferably 250 to 600 parts by weight, and more preferably 300 to 500 parts by weight may be mixed. This is because when nitric acid is less than the above range for the flame retardant, the nitro group may not be sufficiently formed in the flame retardant, whereas when the nitric acid exceeds the above range, excessive strong acid conditions may be formed and the flame retardant may be damaged.

In addition, the reaction temperature of the nitration reaction may be maintained at 18 to 40°C, preferably 20 to 35°C, and more preferably 22 to 30°C. When the reaction temperature is less than the above range, the reaction is difficult to proceed, whereas when the reaction temperature exceeds the above range, the flame retardant may be damaged by excessive heat.

In addition, the reaction time of the nitration reaction may be 2 to 7 hours, preferably 3 to 6 hours, more preferably 4 to 5 hours. When the reaction time is less than the above range, the nitro group may not be sufficiently formed. On the other hand, when the reaction time exceeds the above range, the reaction is all completed within the reaction time and no further reaction occurs, which may waste time and energy.

In addition, after the nitro group of the aromatic flame retardant is reduced, it is preferable to extract the product by putting it in ice water and then filtering it.

On the other hand, in the reduction step of the nitro group, the reducing agent may use a metal and an acid, a metal and an alkali, or a sulfide, or other reduction methods may be used. In particular, the reduction may easily proceed in the presence of HCl/SnCl ₂ .

In the case of reduction using SnCl ₂ , the step b includes 100 parts by weight of the flame retardant formed with the nitro group formed according to the step a, and 200 to 1000 parts by weight of SnCl ₂ (Tin(II)chloride), preferably 300 to 900 parts by weight. Parts, more preferably 400 to 800 parts by weight may be characterized by mixing. When the content of SnCl ₂ is less than the above range, the reaction time may be too long, whereas when the content of SnCl ₂ exceeds the above range, it is difficult to remove a large amount of SnCl ₂ in the process of purifying the product after completion of the reaction. In addition, there may be a concern that the yield may decrease.

In this case, with respect to the hydrochloric acid and ethanol to be added, 100 to 400 parts by weight of ethanol, preferably 150 to 300 parts by weight, more preferably 180 to 250 parts by weight of ethanol may be added based on 100 parts by weight of hydrochloric acid. If the weight part of ethanol is less than the above range, all SnCl ₂ may not be dissolved. On the other hand, if the weight part of ethanol exceeds the above range, the concentration of the reactant decreases due to excessive amounts of the solvent, and the reaction may not be carried out effectively. have.

In addition, the reaction for reducing the nitro group may be to maintain the reaction temperature at 18 to 40°C, preferably at 20 to 35°C, and more preferably at 22 to 30°C. When the reaction temperature is less than the above range, the reaction is difficult to occur, whereas when the reaction temperature exceeds the above range, the flame retardant may be damaged by heat.

In addition, the reaction for reducing the nitro group may have a reaction time of 2 to 8 hours, preferably 3 to 7 hours, and more preferably 4 to 6 hours. When the reaction time is less than the above range, the nitro group may not be sufficiently reduced. On the other hand, when the reaction time exceeds the above range, the reduction is already completed and time and energy are wasted.

In addition, when a flame retardant having an amine group is generated, it is preferable to extract and filter the product through sodium hydroxide.

As an example of introducing an amine group into the flame retardant of the present invention, the reaction of the two steps of introducing an amine group into triphenylene phosphine oxide may be represented as in Scheme 1.

[Scheme 1]

On the other hand, the graphene oxide in a dry powder state is a form in which a plate-like structure is overlapped, and the graphene oxide is dispersed in a solvent, and then the graphene oxide can be separated into a single sheet through ultrasonication. As the solvent, a suitable solvent may be used by a person skilled in the art, but it is preferable to use tetrahydrofuran.

After sonicating the graphene oxide, a flame retardant is added to the graphene oxide solution to induce a reaction between the graphene oxide and the flame retardant, and to form a bond. At this time, the reaction temperature may be maintained at 40 to 100 °C, preferably 50 to 90 °C, more preferably 60 to 80 °C. When the reaction temperature is less than the above range, the reaction is difficult to occur. On the other hand, when the reaction temperature exceeds the above range, the functional groups on the surface of the graphene oxide may be damaged by heat.

In addition, in the step of modifying the graphene oxide with a flame retardant, the reaction time may be 3 to 10 hours, preferably 4 to 9 hours, more preferably 5 to 8 hours. If the reaction time is less than the above range, the graphene oxide is not sufficiently modified with a flame retardant, whereas if the reaction time exceeds the above range, the reaction may have already been completed.

As an example of the step of modifying graphene oxide as a flame retardant, when aminated TPPO is used as a flame retardant, the reaction may be expressed as in Scheme 2 below.

[Scheme 2]

When the step of reforming the graphene oxide is completed, the product is filtered through filtering and washed three or more times using a solvent, and the solvent may be tetrahydrofuran.

The graphene oxide modified with a flame retardant is mixed with a compatibilizer, and at this time, the compatibilizing agent may be introduced into the graphene oxide by reacting with the amine group of the flame retardant or by reacting with the functional group on the surface of the graphene oxide. have. As an example of such a reaction, the reaction between polypropylene (MAPP) grafted with maleic anhydride as a compatibilizer and graphene oxide modified with a flame retardant (aminated TPPO) may be expressed as shown in Scheme 3 below. The maleic anhydride of MAPP and the amine group of the flame retardant can form an amide bond (-CONH-) through reaction, so that a large amount of compatibilizer can be easily attached.

[Scheme 3]

The reaction of introducing the compatibilizer may be to maintain the reaction temperature at 100 to 300°C, preferably 150 to 250°C, more preferably 170 to 220°C. When the reaction temperature is less than the above range, the reaction is difficult to occur, whereas when the reaction temperature exceeds the above range, the reaction product may be damaged by heat.

In addition, the reaction time may be 2 to 16 minutes, preferably 4 to 12 minutes, more preferably 6 to 10 minutes. When the reaction time is less than the above range, it is difficult to sufficiently proceed the reaction, whereas when the reaction time exceeds the above range, thermal degradation of the compatibilizer may occur.

In addition, a mixer is used to mix the compatibilizer and graphene oxide, and the mixer may be an internal mixer. The rotational speed of the mixer may be 30 to 120 rpm, preferably 40 to 100 rpm, more preferably 50 to 80 rpm. If the rotation speed is less than the above range, the shear stress applied to the aggregated graphene oxide may be weak, so that the peeling of the graphene oxide may not be effective. On the other hand, if the rotation speed exceeds the above range, the uniformity of the mixture Apart from this, the reaction between the graphene oxide and the compatibilizer may not occur sufficiently.

On the other hand, the flame-retardant polypropylene composition of the present invention, polypropylene 76 to 98% by weight, preferably 79 to 95% by weight, more preferably 82 to 94% by weight, and the graphene oxide filler 2 to 24% by weight, Preferably it may include 5 to 21% by weight, more preferably 6 to 18% by weight. When the content of the graphene oxide filler for polypropylene is less than the above range, it may not be able to sufficiently play the role of the filler. On the other hand, when it exceeds the above range, the processability of the polypropylene may be deteriorated. It can exhibit appropriate flame retardancy in a commercial aspect.

Such a flame retardant polypropylene composition has excellent flame retardancy due to the flame retardant included in the graphene oxide filler, and particularly, when a phosphorus flame retardant is used, toxicity to the human body and the environment can be prevented. In addition, due to the compatibilizing agent included in the graphene oxide filler, the compatibility of the filler and the base polymer, polypropylene, is increased, thereby improving the dispersibility of the filler. In general, as the content of the filler increases, the viscosity of the polymer increases, which adversely affects the molding of the polymer and the dispersion of the filler.The filler of the present invention can exhibit a sufficient effect with only a small amount of addition due to its excellent dispersibility in the base polymer. And, it is possible to prevent a problem due to the addition of a high content filler.

On the other hand, due to the excellent mechanical properties of graphene itself, the flame-retardant polypropylene composition including the graphene oxide filler of the present invention has excellent mechanical properties, and in particular, it has excellent tensile modulus (Young's modulus) and tensile strength ( Tensile strength). The tensile modulus is a value representing the stiffness of a material, and is defined as a ratio of stress and strain. In addition, the tensile strength is a value obtained by dividing the maximum load until fracture occurs by the cross-sectional area of the material.

In addition, the flame-retardant polypropylene composition may be prepared by melt blending the graphene oxide filler and polypropylene, but is not limited thereto, and a known method for combining the filler and the polymer may be used. However, the melt mixing method does not require a solvent and is an advantageous method for mass production, and is a preferred method for producing the flame-retardant polypropylene of the present invention.

The melt mixing may be mixed using an extruder, the extruder is preferably a twin screw extruder, and the rotational speed of the extruder is 50 to 500 rpm, preferably 100 to 400 rpm, more preferably It can be 150 to 300 rpm. When the rotational speed is less than the above range, the shear stress applied to the mixture is weak, making it difficult to effectively disperse the filler in the matrix. On the other hand, when the rotational speed exceeds the above range, the viscosity of the mixture may be low, making extrusion difficult.

In addition, the melt mixing may maintain the reaction temperature at 140 to 350 °C, preferably 150 to 300 °C, more preferably 160 to 240 °C. When the reaction temperature is less than the above range, polypropylene may not be melted, whereas when the reaction temperature exceeds the above range, deterioration may occur.

As an embodiment of the flame-retardant polypropylene composition according to the present invention, when the aminated TPPO and graphene oxide into which a compatibilizer is introduced are added to polypropylene, the reaction can be expressed as shown in Scheme 4 below.

[Scheme 4]

In the present invention, in order to ensure the flame retardancy of the resin in the manufacturing process, a new operating variable called'flame retardant index' was introduced. The'flame retardant index' is defined by the following formula:

Flame retardant index = (flame retardant reaction time / compatibilizer reaction time)

× (compatibilizer mixing rpm / resin mixing rpm).

In the formula, the flame retardant reaction time refers to the reaction time of the graphene oxide and the flame retardant, and the compatibilizer reaction time refers to the reaction time of the graphene oxide modified with the flame retardant with the compatibilizer. In addition, the compatibilizer mixing rpm refers to the mixing rpm when the graphene oxide modified with the flame retardant reacts with the compatibilizer, and the resin mixing rpm refers to the graphene oxide filler reacted with the compatibilizer to be mixed with a resin such as polypropylene. It indicates the rpm of the time.

In the present invention, the flame retardant index may be 7 to 25, preferably 10 to 20, more preferably 12 to 17. If the flame retardancy index is less than the above range, sufficient flame retardancy cannot be ensured. Conversely, if the flame retardant index exceeds the above range, compatibility is poor and operation costs are excessive.

Hereinafter, an embodiment of the present invention will be described.

Example

Produce Yes 1: Amination of triphenylene phosphine oxide

In order to generate nitro group (-NO ₂ ) in triphenylene phosphine oxide (TPPO), TPPO and nitric acid were performed at room temperature in a molar ratio of 1:4 for 4 hours, and a yield of about 84% was shown. . After the reaction was completed, the mixture was put in ice water to extract the product, and then filtered using a filtering method.

Then, in order to reduce the nitro group to the amine group through a reduction reaction, SnCl ₂ (Tin(II)chloride) was mixed with TPPO where the nitro group was generated, and the weight ratio of TPPO and SnCl ₂ was 1:6. In addition, hydrochloric acid and ethanol were mixed in a volume ratio of 1: 2 and proceeded at room temperature for 5 hours, and a yield of about 65% was shown. The mixed solution after the reaction was completed was poured into sodium hydroxide (NaOH) to extract the product, and filtered through filtering to obtain aminated TPPO (aTPPO).

Preparation Example 2: Preparation of modified graphene oxide with aminated triphenylene phosphine oxide

After the dried powdered graphene oxide was dispersed in a tetrahydrofuran solvent, it was peeled off into sheets through ultrasonication. Here, the aminated TPPO prepared according to Preparation Example 1 was dissolved and reacted for 6 hours at 60° C. to induce a covalent bond between the graphene oxide and the aminated TPPO. After 6 hours, the modified graphene oxide was filtered through filtering, and the unreacted material was removed through three or more washing processes using tetrahydrofuran to obtain a modified graphene oxide with aminated TPPO.

Test Example 1: Analysis of graphene oxide modified with aminated TPPO

The graphene oxide (aTPPO-GO) modified with aminated TPPO prepared according to Preparation Example 2 was analyzed through an infrared spectral spectrum (FIG. 2). As the reaction time passed, the epoxy group peak (920 to 1010 cm ^-1 ) and the carboxylic acid group peak (1690 to 1780 cm ^-1 ) disappeared, and the amine group peak (680 to 720 cm ^-1 ) and the amide group disappeared. It was confirmed that a peak corresponding to (1570 to 1610 cm ^-1 ) was generated. This is a result of the reaction of the aminated TPPO with the carboxylic acid group and the epoxy group on the surface of the graphene oxide.

Meanwhile, aTPPO-GO prepared according to Preparation Example 1 was analyzed by X-ray photoelectron spectroscopy (FIG. 3). Through this, the amount of phosphorus atoms of the modified graphene oxide increased as the reaction time passed, and it can be seen that the graphene oxide was well modified with aTPPO.

Preparation Example 3: Preparation of graphene oxide filler incorporating polypropylene grafted with maleic anhydride

The graphene oxide modified with the aminated TPPO prepared according to Preparation Example 2 was finally modified with polypropylene grafted with maleic anhydride through reactive compatibilization to prepare a graphene oxide filler. This reaction was carried out for 8 minutes at 190° C. and 60 rpm using an internal mixer.

Example 1: Preparation of flame retardant polypropylene composition

The graphene oxide filler prepared according to Preparation Example 3 was melt blended with polypropylene to prepare a composite material. This method was fabricated at 200 rpm at 190°C using a twin-screw extruder. The composition ratio of the finally produced composite material is shown in Table 1.

Comparative Examples 1 to 4: Polypropylene composition comprising graphene oxide into which polypropylene and aminated TPPO are introduced

Comparative Example 1 is pure polypropylene, and Comparative Examples 2 to 4 were prepared in the same manner as in Example 1 as shown in the composition ratio of Table 1 below.

PP(wt%) aTPPO-GO (wt%) MAPP(phr) Comparative Example 1 100.0 0 0 Comparative Example 2 99.5 0.5 0 Comparative Example 3 99.0 1.0 0 Comparative Example 4 98.0 2.0 0 Example 1 98.0 2.0 5.0

Test Example 2: Measurement of tensile modulus and tensile strength of polypropylene composition

The tensile modulus (Young's modulus) and tensile strength (tensile strength) were measured for Example 1 and Comparative Examples 1 to 4 (Table 2).

Young's modulus(GPa) Rate of increase
(%) Tensile strength(MPa) Rate of increase
(%) Comparative Example 1 1.26 - 28.7 - Comparative Example 2 1.31 4 29.3 2 Comparative Example 3 1.38 8 30.7 6 Comparative Example 4 1.40 12 31.3 9 Example 1 1.52 28 34.5 20

It was confirmed that both the tensile modulus and tensile strength increased as the content of the aminated TPPO-modified graphene oxide increased. In addition, when using the compatibilizer MAPP together with the graphene oxide modified with the flame retardant as in Example 1, it was found that the increase rate of the tensile modulus and tensile strength was the highest, which increases the compatibility between the polypropylene and the filler. This is a result that appears as the dispersibility increases.

Test Example 3: Comparison of the limiting oxygen index of Example 1 and Comparative Examples 1 to 4

Limiting Oxygen Index (LOI) was measured for Example 1 and Comparative Examples 1 to 4 (Table 3).

Marginal Oxygen Index (%) Increase rate (%) Comparative Example 1 18.0 - Comparative Example 2 20.1 2.1 Comparative Example 3 20.6 2.6 Comparative Example 4 21.1 3.1 Example 1 22.1 4.1

Comparative Examples 5 to 8: Polypropylene composition containing pure graphene oxide

Comparative Examples 5 to 8 were prepared through the same method as in Example 1, and each composition ratio is shown in Table 4 below. Comparative Examples 5 to 7 are compositions comprising polypropylene (PP) and pure graphene oxide (GO), and Comparative Example 8 is a composition comprising polypropylene, pure graphene oxide, and MAPP.

PP(wt%) GO(wt%) MAPP(phr) Comparative Example 5 99.5 0.5 0 Comparative Example 6 99.0 1.0 0 Comparative Example 7 98.0 2.0 0 Comparative Example 8 98.0 2.0 5.0

Test Example 4: Comparison of the limiting oxygen index of Example 1, Comparative Examples 1, and 5 to 8

The limiting oxygen index (LOI) was measured for Example 1, Comparative Examples 1, and 5 to 8 (Table 5).

Marginal Oxygen Index (%) Increase rate (%) Comparative Example 1 18.0 - Comparative Example 5 18.8 0.8 Comparative Example 6 19.5 1.5 Comparative Example 7 20.5 2.5 Comparative Example 8 20.4 2.4 Example 1 22.1 4.1

From Comparative Examples 5 to 7, the limiting oxygen index (LOI) of the polypropylene nanocomposite material increased as the content of pure graphene oxide increased. This is because the plate-shaped graphene oxide can form a heat barrier film during combustion, and thus has its own flame retardancy.

In addition, Comparative Examples 7 and 8 containing polypropylene and pure graphene oxide, which differ only in the presence or absence of MAPP, did not have a significant difference in the limiting oxygen index, but graphene oxide modified with MAPP as a flame retardant as in Example 1. When used together, the limiting oxygen index increased. 4 is a graph comparing the limiting oxygen index of Comparative Examples 1 to 8 and Example 1.

In the above, preferred embodiments of the present invention have been described, but the present invention is not limited to the specific embodiments described above, and those of ordinary skill in the art can implement various modifications without departing from the gist of the present invention. Of course it is possible. Therefore, the scope of the present invention should not be construed as limited to the above embodiments, and should be defined by the claims and equivalents to the claims described later.

GO: graphene oxide
PP: polypropylene
MAPP: Maleic anhydride grafted polypropylene (MAPP)
TPPO: triphenylene phosphine oxide
aTPPO: aminated triphenylene phosphine oxide
aTPPO-GO: graphene oxide modified with aminated triphenylene phosphine oxide

Claims (20)

100 parts by weight of graphene oxide modified with a flame retardant, and
Including 20 to 1000 parts by weight of a compatibilizer,
The flame retardant is bonded to a functional group present on the surface or edge of the graphene oxide,
The compatibilizer is bound to the graphene oxide or the flame retardant,
The flame retardant is a phosphorus-based flame retardant having an amine group, characterized in that, graphene oxide filler. The method according to claim 1,
The compatibilizer is a reactive compatibilizer, characterized in that, graphene oxide filler. delete The method according to claim 1,
The flame retardant is a phosphate-based flame retardant, phosphonate-based flame retardant, phosphinate-based flame retardant, phosphazene-based flame retardant, melamine phosphate-based flame retardant, ammonium polyphosphate-based flame retardant, ammonium phosphinate-based flame retardant, phosphophenanthrene-based flame retardant, phos Pin oxide-based flame retardant and characterized in that selected from the group consisting of a mixture thereof, graphene oxide filler. The method according to claim 1,
Graphene oxide modified with the flame retardant,
35 to 65% by weight of graphene oxide, and
It characterized in that it comprises 35 to 65% by weight of a flame retardant, graphene oxide filler. (A) forming an amine group (-NH ₂ ) in the aromatic flame retardant;
(B) dispersing graphene oxide in a solvent and performing ultrasonic treatment;
(C) modifying graphene oxide with a flame retardant by adding a flame retardant in which the amine group is formed to the graphene oxide solution; And
(D) mixing the graphene oxide modified with the flame retardant with a compatibilizer to introduce the compatibilizer to the graphene oxide; including, a method for producing a graphene oxide filler. The method of claim 6,
Step A,
(a) forming a nitro group (-NO ₂ ) in the aromatic flame retardant; And
(b) reducing the aromatic flame retardant in which the nitro group is formed; characterized in that it comprises, a method for producing a graphene oxide filler. The method of claim 7,
The step a is characterized in that maintaining the reaction temperature at 18 to 40 ℃, the method of producing a graphene oxide filler. The method of claim 7,
The step a is characterized in that the reaction time is 2 to 7 hours, the method of producing a graphene oxide filler. The method of claim 7,
Step b,
100 parts by weight of the flame retardant formed with the nitro group, and
SnCl ₂ (Tin(II)chloride), characterized in that mixing 200 to 1000 parts by weight, a method for producing a graphene oxide filler. The method of claim 10,
Step b,
100 parts by weight of hydrochloric acid, and
A method for producing a graphene oxide filler, characterized in that 100 to 400 parts by weight of ethanol are additionally added. The method of claim 7,
Step b,
The method for producing a graphene oxide filler, characterized in that maintaining the reaction temperature at 18 to 40 ℃. The method of claim 7,
The step b, characterized in that the reaction time is 2 to 8 hours, a method of producing a graphene oxide filler. The method of claim 6,
The step C is characterized in that maintaining the reaction temperature at 40 to 100 ℃, the method of producing a graphene oxide filler. The method of claim 6,
The step C is characterized in that the reaction time is 3 to 10 hours, the method of producing a graphene oxide filler. The method of claim 6,
The step D, characterized in that maintaining the reaction temperature at 100 to 300 ℃, the method for producing a graphene oxide filler. The method of claim 6,
The step D, characterized in that the reaction time is 2 to 16 minutes, the method of producing a graphene oxide filler. The method of claim 6,
The step D is a mixer, characterized in that the rotation speed of the mixer is 30 to 120 rpm, the method for producing a graphene oxide filler. 76 to 98% by weight of polypropylene, and
A flame-retardant polypropylene composition comprising 2 to 24% by weight of the graphene oxide filler of any one of claims 1, 2, 4, or 5. The method of claim 19,
The flame-retardant polypropylene composition is characterized in that it is prepared by melt-mixing the graphene oxide filler and polypropylene of any one of claims 1, 2, 4, or 5.

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