KR100371232B1 - Polypropylene polymer composite comprising an organic layered clay which has excellent fire resistance and production process therefor - Google Patents

Abstract

The present invention relates to a polypropylene-organic clay composite, and more particularly to 1 to 30% by weight of a modified polypropylene containing a functional group (component A) and an amine-based non-halogen flame retardant chemically bonded to the functional group of the component A or amines. Flame retardance of 1 to 20% by weight of the layered clay mineral (organic component B) organically composed of the non-halogen flame retardant and the alkylammonium compound and 50 to 98% by weight of the polyolefin resin matrix (component C) in which the A and B components are dispersed. A good polypropylene-organic clay composite. The composite of the present invention is excellent in the dispersibility of nanometer-sized organic clay minerals, excellent mechanical properties such as stiffness, heat resistance, impact resistance, other flame retardancy, transparency, gas and liquid permeation inhibition ability, and accordingly thinning And light weight is possible.

Description

Polypropylene polymer composite comprising an organic layered clay which has excellent fire resistance and production process therefor}

The present invention relates to a polypropylene-organic clay composite having excellent flame retardancy and a method for preparing the same, and more particularly, by dispersing a clay mineral of a layered structure organicized with an amine-based non-halogen flame retardant in a polymer resin, The present invention relates to a polypropylene-organic clay composite and a method for producing the same, which further supplement the disadvantages of the conventional inorganic filler / reinforcement filler composite having a particle size of 1 micrometer or more.

In the past, many studies have been conducted through the addition of a flame retardant for the purpose of improving the flame retardancy of polyolefin resin. However, in the case of this prior art, most flame retardants are very expensive compared to the resin, and in some cases difficult to process with the resin. In addition, it greatly reduces other mechanical properties or heat resistance of the resin, and had a problem that can cause environmental problems in terms of recycling the finished product.

On the other hand, recently, a number of techniques for dispersing an organic inorganic layer compound in a polymer matrix by dispersing individual unit layers to a nanometer size, thereby increasing mechanical properties and heat resistance as well as flame resistance. These techniques were initially derived from the development of nylon 6-layered clay mineral composites at Toyota Research in Japan. This technique was used to prepare nylon6-layered clay mineral composites with exfoliated or intercalated structures. As a result, it was found that the nylon 6-layered clay mineral composite including 5% layered clay mineral was significantly improved in thermal and mechanical properties compared to pure nylon 6. That is, according to Sample Journal, Vol. 33, pp. 40-46 (1997), nylon 6-layered clay mineral composites containing 5% inorganic silicate clay minerals have a pure peak heat release rate. It has the same amount of heat of combustion, while being 63% lower than that of the resin. Therefore, not only the flame retardancy is improved, but also the mechanical properties or heat resistance, which have been reduced by the conventional flame retardant addition, have been greatly improved.

In addition, the development of layered clay mineral composites with the polymer resins such as polystyrene, epoxy, polyester, and polyolefin has been actively progressed.

BACKGROUND OF THE INVENTION In the polyolefin, there has been a technique of incorporating inorganic materials such as talc and mica into the inorganic filler by mechanical means in order to improve the mechanical properties of the polyolefin resin. However, in such a prior art, the dispersion of the inorganic substance was insufficient because the particles of the inorganic substance themselves were multi-layer aggregates, and also the compatibility with the polyolefin matrix was poor.

To improve the dispersibility of inorganic materials in resins, many techniques have been published so far to disperse individual unit layers of layered inorganic compounds in a nanometer size in a polymer matrix. According to these techniques, organic materials such as monomers or polymers do not sufficiently penetrate into the interlayer spaces of the layered inorganic material without surface-treating the layered inorganic material with the lipophilic material, and the unit layers of the layered inorganic material are sufficiently uniform in the polymer matrix. It is known that it can not be distributed.

To further facilitate uniform dispersion of the layered inorganic material to the polymer resin, U.S. Pat. No. 4,889,885 discloses sodium or potassium ions which exist in a natural state between unit layers of multilayered particulate layered materials such as inorganic silicates. : Alkylammonium ions or functionalized organosilanes), followed by mixing of these layered materials with monomers or oligomers of the polymer. This cation exchange action makes the existing hydrophilic silicates lipophilic and can extend the interlayer distance of the layered material, thereby improving dispersibility to the resin.

See also Journal of Appl. Polym. Scien., Vol. 55, pp. 119 to 123 (1995) reported a technique for producing polyamide peelable composites using inorganic silicates treated with 12-aminolauric acid.

In Japanese Patent Laid-Open No. 10-182892, an intercalation of a polyolefin oligomer containing a functional group in an organic layered clay mineral is performed to extend the interlaminar distance of the clay mineral to some extent, and then the composite material is mixed with an olefin resin to form a layer. A method is described in which clay minerals are dispersed in a matrix of olefinic resins.

However, the prior art as described above is mainly intended to improve the dispersibility only by the organicization of the layered inorganic material, there was a limit in improving the dispersibility.

An object of the present invention is to use a modified flame retardant to inorganic materials such as layered clay minerals and to modify the polymer resin with a specific material so that the chemical bond between the layered inorganic material and the polymer resin matrix substituted with the flame retardant is substituted Accordingly, to maximize the compatibility and dispersibility of the layered inorganic material and the polymer matrix, to provide a polypropylene-organic clay composite and a method for producing the composite having improved mechanical properties, heat resistance and flame retardancy significantly.

The polypropylene-organic clay composite according to the present invention comprises 1.0 to 30% by weight of a modified polypropylene (component A) containing a functional group and an amine nonhalogen flame retardant chemically bonded to a functional group of the component A or an amine nonhalogen flame retardant and alkyl A polypropylene-organic clay composite composed of 1.0 to 20% by weight of a layered clay mineral (component B) organicated with an ammonium compound and 50 to 98% by weight of a polyolefin resin matrix (component C) in which the A and B components are dispersed.

The modified polypropylene (component A) used in the present invention is obtained by modifying polypropylene with a functional monomer having a high polar chemical structure. Polypropylene used in the production of modified polypropylene in the present invention is an isotactic polypropylene homopolymer, ethylene / propylene copolymer having a melt index (MI) of 1.0 to 100 g / 10 minutes (ASTM D1238, 230 ℃) and crystallinity , Propylene / α-olefin nonconjugated diene compound copolymer (e.g. EPDM), and the like, and the α-olefin includes ethylene, butene-1, heptene-1, hexene-1,4-methylpentene, These may be used alone or in combination of two or more thereof. If the melt index of the polypropylene is less than 1.0 g / 10 minutes, the moldability of the parts is not good, the productivity is lowered, while if the melt index exceeds 100 g / 10 minutes, the impact strength is sharply lowered. Examples of the highly polar functional monomer for modifying the polypropylene include unsaturated carboxylic acids or derivatives thereof maleic anhydride, itaconic anhydride, ditraconic anhydride, hydroxyl, glycidyl methacrylate, carboxylic acid ester, and carboxyl. Acid ethers, thiocarboxylic acids, alkoxycarboxylic acids such as methoxycarboxylic acid, ethoxycarboxylic acid and the like can be exemplified. The site where the functional group is covalently bonded to the polypropylene may be the end group of the molecule, or may be bonded in the middle of the molecular chain. Of the various functional group monomers described above, maleic anhydride which is capable of causing a chemical reaction with a functional group such as an amine group of a non-halogen flame retardant bonded to a layered clay mineral and giving high intercalation ability is particularly preferable.

When modifying a polypropylene with the said functional monomer, the said substance can be used individually or in mixture of 2 or more types. As a method of modifying polypropylene, polypropylene may be dissolved in a suitable organic solvent and kneaded by adding a functional monomer and a radical generator, or graft copolymerization may be performed for each of the above components using an extruder. have.

The modified polypropylene used in the present invention is preferably 0.10 to 10% by weight, based on the weight of the modified polypropylene, in the amount of the unsaturated carboxylic acid or derivative thereof that is a modifier. If it is less than 0.1% by weight, it is difficult to express the intercalation effect. If it exceeds 10% by weight, a large amount of unreacted denaturant remains in the polypropylene, thereby causing a problem of deterioration in compatibility with the actual polypropylene. have.

The preferable molecular weight of modified polypropylene is about 1,000-500,000. It is difficult to penetrate between the layered clay mineral layers due to the low molecular weight of the molecular weight range of the above, lowering the physical properties of the clay composite material, insufficient expansion between layers of layered clay minerals, and very high melt viscosity on the high molecular weight side. There is a number.

The content of the modified polypropylene is preferably 1.0 to 30% by weight based on the weight of the entire polypropylene-organic clay composite. If the content of the modified polypropylene is less than 1.0% by weight, the interfacial adhesion between the organic layered clay mineral and the polypropylene resin cannot be sufficiently maintained, so there is no contribution to the intercalation effect and the improvement of physical properties. Physical property improvement effect is not expressed.

The organic layered clay mineral (component B) used in the present invention means a non-halogen flame retardant alone or a layered clay mineral organicated by a non-halogen flame retardant and an alkylammonium compound. Representative examples of the layered clay minerals used in the present invention include smectite-based layered clay minerals such as montmorillonite, hectorite, saponite, nontronite, and baydelite, vermiculite and heroisite. Preferred layered clay minerals have a modified polypropylene having functionalities on the layer which have ions (e.g. sodium, calcium ions) which can be exchanged by charge and ions, preferably onium ions (e.g. ammonium cations). The use of a large contact area of is preferable because it is easy to greatly expand the interlayers of layered clay minerals. Typically the negatively charged cation exchange capacity on the surface of the layered clay mineral is at least 20 milliequivalents, preferably 50 to 200 milliequivalents per 100 grams of clay mineral.

In the case of less than 20 milliequivalents / 100g, since the organicization by the exchange of organic onium ions is insufficient, it may become difficult to expand the layered clay mineral as a result. If the cation exchange capacity exceeds 200 milliequivalents / 100 g, since the bonding force between the unit particle layers of the layered clay mineral is strong, it is difficult to penetrate into the interlayer by ion exchange of organic onium ions and consequently the expansion of the layered clay mineral. It may be insufficient.

Organic onium ions are mainly composed of cationic groups and lipophilic groups, where cationic groups serve to exchange ions on the clay mineral surface, and lipophilic groups interact with organic materials such as monomers or polymers to form interlayer distances. Increase to facilitate interlayer penetration of organics. Typically, functional groups reactive with organic substances such as monomers or polymers include nucleophilic or electrophilic functional groups capable of electrophilic or nucleophilic substitution reactions, coupling reactions and ring-opening reactions. Examples of such reactors include epoxy, amino, carboxy, hydroxy, isocyanate, halogen and epichlorohydrin.

Representative examples of organic onium ion compounds that can be used as organic intercalating agents in the present invention include octadecyl, hexadecyl, tetradecyl, quaternary ammonium salts such as octadecyl trimethylammonium salts with dodecyl residues, ditetradecyl dimethyl ammonium salts, Preferred ammonium salts include bis (2-hydroxyethyl) methyl octadecyl ammonium salts, dihydroxyethyl methylhydrogen ammonium salts.

As the organic intercalant, an amine non-halogen flame retardant alone or an amine non-halogen flame retardant and an alkylammonium salt may be used together. In addition, the amine-based non-halogen flame retardant used in the present invention includes melamine, melamine cyanurate, melamine phosphate and the like.

The content of the organic layered clay mineral (component B) is preferably 1.0 to 20% by weight based on the weight of the entire polypropylene-organic clay composite. If the content of the organic layered clay mineral is less than 1.0% by weight, there is no contribution to the improvement of physical properties. When the content of the organic layered clay mineral is less than 20% by weight, the aggregation of unit particles increases greatly, making it difficult to disperse nanometer-sized particles. not.

An example of a method for producing an organic layered clay mineral substituted with an amine non-halogen flame retardant of the present invention includes hydrochloric acid in which a flame retardant alone or a flame retardant and an alkylammonium salt are dissolved together in an aqueous layered clay mineral solution completely dispersed in hot water at 80 ° C. And a method of producing the mixture by stirring a hot aqueous solution containing 80 ° C. and stirring the mixture.

The polyolefin resin matrix (component C) used in the present invention has a melt index of 1.0 to 100 g / 10 minutes and is preferably an isotactic polypropylene homopolymer or an ethylene-propylene copolymer having crystallinity. If the melt index is less than 1.0g / 10 minutes, the moldability is not good, the productivity is lowered, while if the melt index exceeds 100g / 10 minutes, the impact strength is sharply lowered.

The polypropylene-organoclay composites of the present invention may contain various other additives such as antioxidants, nucleating agents, lubricants, colorants, release agents, antistatic agents, pigments. Any additives and their amounts can be adapted and adjusted according to various factors including the desired end use, characteristics.

In the method for producing the polypropylene-organic clay composite of the present invention, the reaction of the modified polypropylene containing a functional group such as a layered clay mineral functionalized with an amine group of an amine-based non-halogen flame retardant and a maleic anhydride group is preferably used. It can be prepared by manipulating the solution reaction using a harmful solvent and melt kneading using an appropriate mixer (eg extruder, Banbury mixer) in any order. Suitable inert solvents may be hydrocarbons (e.g., benzene, toluene, xylene) to dissolve modified polyolefins with functional groups, and at temperatures ranging from about 100 to 120 ° C. which are sufficient to dissolve organic layered clay minerals and modified polypropylenes. The higher the temperature, the faster the reaction. The reaction time may vary depending on the reactivity between the two materials.

The organic layered clay mineral and the modified polypropylene as described above are subjected to solution mixing or melt mixing, followed by melt kneading by adding a polyolefin resin matrix component.

In the melt kneading process of the present invention, a mechanical shearing method using an extruder, a Benbury mixer or a brabender mixer is used at a temperature that is higher than the melting point of the polymer. The melt of the composite and the organic ionic material such as the inserted flame retardant is shear mixed until peeled to the desired degree.

The above manufacturing method is advantageous in that more tie chains can be produced between the crystals of polypropylene in the composite of the present invention. These linking chains increase the interfacial adhesion by connecting the crystals of the polypropylene crystal regions together, thereby increasing modulus and tensile strength when stress or strain is applied to the polymer. In addition, since the crack growth requires the cutting of the connection chains between the crystal planes on both sides of the rupture portion, an increase in the relative amount of the connection chains may slow the crack growth by that much.

Hereinafter, the present invention will be described in detail through Examples and Comparative Examples. However, these Examples and Comparative Examples are for illustrative purposes only and the present invention is not limited thereto.

Example

Examples 1 to 4 below are examples according to the present invention, and Comparative Examples 1 to 4 are examples for comparison with the present invention. Table 1 shows the contents of the components and the physical properties of the prepared composites for Examples and Comparative Examples.

Description of each component used in Examples 1-4 and Comparative Examples 1-4 of Table 1 is as follows.

1) Polypropylene: Ethylene-propylene block copolymer having a melt index (MI) of 5 g / 10 min (230 ° C.).

2) Montmorillonite (1): Montmorillonite substituted with octadecyl ammonium cation and melamine phosphate as flame retardant. The clay has an interlayer distance of 18 km2 and is made from Southern Clay Products, Inc., sodium montmorillonite from Texas.

3) Montmorillonite (2): Montmorillonite substituted with melamine phosphate, a flame retardant, having an interlaminar distance of 15 kPa and sodium montmorillonite of Southern Clay Products, Inc. (Texas). It is a product manufactured using.

4) Montmorillonite (3): Sodium montmorillonite with an interlayer distance of 11 Å and a product of Southern Clay Products, Inc., Texas.

5) Modified polypropylene (1): A polypropylene homopolymer containing 2.0% by weight of polypropylene by weight of reacted maleic anhydride.

6) Modified polypropylene (2): A polypropylene homopolymer containing 0.1% by weight of reacted maleic anhydride based on polypropylene weight.

Examples 1 to 3

In Table 1 below, 150 g of modified polypropylene (1) was completely dissolved in 2,000 ml of xylene at about 100 to 120 ° C., including a predetermined amount of antioxidant, and then 150 g of montmorillonite (1) was added thereto. Stir vigorously for at least 4 hours. Next, precipitated using 3,000 ml of acetone at room temperature. The precipitate thus obtained was dried in a vacuum oven at 100 ° C. for at least 12 hours to obtain a complex in which maleated polypropylene was coupled to the surface of an organic clay mineral and connected to an amide compound. This was confirmed by using infrared spectroscopy and nuclear magnetic resonance spectroscopy (NMR). 266 g of the organic clay compound thus obtained was dry blended with 1734 g of polypropylene, 4 g of antioxidant, and Henschel mixer, and then all were added to the main hopper in a SW TEX44ALPHA biaxial kneading extruder at once and melt kneaded to prepare a composite. The dispersibility of the clay particles was measured by the X-ray diffraction, and the interlaminar distance of the layered clay minerals contained in the test piece was measured. The dispersion state of the layered clay particles in the composite was investigated by transmission electron microscope (TEM) observation. Mechanical properties were injected into Samsung Klockner FCM-110 (110 tons of clamping force) to prepare specimens specified by the American Society for Testing and Materials (ASTM) standards, and the limiting oxygen index was measured for flexural modulus, thermal strain temperature and flame retardancy.

Example 4

First, 1500 g of modified polypropylene (1) and 1500 g of montmorillonite (1) were dry blended using the ingredients and blending ratios of Table 1 below, followed by melt mixing using a kneader blender to obtain an organic clay compound master batch. 266 g of the organic clay compound thus obtained was dry blended again with 1734 g of polypropylene, an additive and a Henschel mixer, and then all were added to the main hopper at once in a SW TEX44ALPHA biaxial kneading extruder and melt kneaded to prepare a composite.

Comparative Examples 1 to 4

After mixing and blending polypropylene and additives at the same time with a Henschel mixer including clay mineral montmorillonite alone or modified polypropylene in the ingredients and blending ratios of Table 1 below, all at once in the main hopper in a SW TEX44ALPHA biaxial kneading extruder. Charged and melt kneaded to prepare a composite.

The interlaminar distance and dispersion condition of each layered clay mineral in each composite specimen were as follows.

1) X-ray diffraction method: RIG-2000, Rigaku Co., Ltd., Japan, was used, and CuKα (α = 0.15 nanometer) light was used for observation.

2) Transmission electron microscopy (TEM): The test piece was cut into microtomes and stained with ruthenium tetraoxide. The device used JEOL 2000EX and the acceleration voltage during observation was 100 kV. Here, the observation results were evaluated by dividing O and X, and O is good in dispersibility, so that the layered clay mineral particles are not visible to the naked eye, and the interlayer distance enlargement of 10 or more is compared with the original interlayer distance of the layered clay mineral. It means that the dispersibility of layered clay minerals is good in electron microscope observation. In addition, X is poor in dispersibility, and the particles of layered clay minerals are visible to the naked eye, and the distance between layers is less than 10 compared to the original layer distance of the layered clay minerals, and the layered clay minerals are aggregated in the transmission electron microscope observation. It means that the dispersibility is poor.

Test conditions for each test property are as follows.

1) Flexural modulus

It was measured at room temperature according to the American Society for Testing and Materials (ASTM) D790.

2) Heat deflection temperature

It was measured under low load (4.6KG) according to the American Society for Testing and Materials (ASTM) D648.

Flame retardancy test conditions are as follows.

1) Limiting oxygen index (LOI)

In accordance with the American Society for Testing and Materials (ASTM) D2863, the minimum oxygen concentration, or oxygen index, required for flame combustion was measured by flowing a mixture of oxygen and nitrogen.

Table 1. Examples and Comparative Examples

Example Comparative example Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Composition (% by weight) Polypropylene 86.6 86.6 79.9 86.6 100 93.3 94.6 79.9 Montmorillonite (1) 6.7 6.7 6.7 Montmorillonite (2) 6.7 6.7 6.7 Montmorillonite (3) 5.4 Modified Polypropylene (1) 6.7 6.7 13.4 6.7 Modified Polypropylene (2) 13.4 Dispersibility Interlayer distance 55 48 58 42 15 12 20 Dispersion O O O O - X X X Mechanical property Flexural modulus (MPa) 2,270 2,150 2,440 2,180 1,360 1,760 1.720 1,890 Heat deflection temperature (℃) 120 119 122 119 105 108 107 106 Flame retardant Limit Oxygen Index (LOI) 22.3 23.0 21.9 22.1 17.5 19.9 18.4 19.8

As can be seen in Table 1, Examples 1 to 4 according to the present invention is far more widely dispersed in the organic clay layer in terms of dispersibility compared to Comparative Examples 1 to 4, and the dispersion state was also good. In terms of mechanical properties, the heat deflection temperature was high, the flexural strength was high, and the limit oxygen index, that is, the flame retardancy, was superior to Comparative Examples 1 to 4 in terms of mechanical properties.

As can be seen in the above examples and comparative examples, the polypropylene-organic clay composite prepared according to the present invention is a polymer obtained by peeling a clay mineral having a layered structure in which a flame retardant is substituted with a polypropylene basic unit and dispersing it in a polymer resin. The resin's physical properties and heat resistance as well as its flame retardancy are excellent, and accordingly, it is possible to make thin film, defect, flame retardant of the product and to replace existing materials in automobiles, industrial materials, electrical and electronics.

Claims (8)

1 to 30% by weight of modified polypropylene containing a functional group (component A) and an amine nonhalogen flame retardant chemically bonded to the functional group of the component A alone or an organic layered clay mineral composed of an amine nonhalogen flame retardant and an alkylammonium compound (component B A polypropylene-organic clay composite having excellent flame retardancy of 1 to 20% by weight and 50 to 98% by weight of the polyolefin resin matrix (component C) in which the A and B components are dispersed. According to claim 1, wherein the modified polypropylene of the component A is a polypropylene homopolymer, ethylene / propylene copolymer, or propylene / α-olefin non-conjugated diene compound copolymer modified by an unsaturated carboxylic acid or derivatives thereof Excellent flame retardant polypropylene-organic clay composite. The method of claim 2, wherein the unsaturated carboxylic acid or derivative thereof is maleic anhydride, itaconic anhydride, ditraconic anhydride, hydroxyl, glycidyl methacrylate, carboxylic acid ester, carboxylic acid ether, or thiocar An excellent flame retardant polypropylene-organic clay composite, characterized in that an acid. The polypropylene-organic clay composite having excellent flame retardancy according to claim 2 or 3, wherein the amount of the unsaturated carboxylic acid or its derivative is 0.10 to 10% by weight relative to the polypropylene. The polypropylene-organic clay composite according to claim 1, wherein the layered clay mineral is montmorillonite, hectorite, saponite, nontronite, baydelite, vermiculite, or heroisite. The polypropylene-organic clay composite having excellent flame retardancy according to claim 1, wherein the amine-based nonhalogen flame retardant is melamine, melamine cyanurate, or melamine phosphate. The polypropylene-organic clay composite having excellent flame retardancy according to claim 1, wherein the C component is polypropylene. First, a modified polypropylene containing a functional group (component A) and an amine nonhalogen flame retardant alone or an amine nonhalogen flame retardant and an alkylammonium compound (component B) are melt-mixed with an appropriate inert solvent or with shear force. And melt-mixing a polyolefin resin matrix (component C) with shear force, wherein the polypropylene-organic clay composite having excellent flame retardancy according to claim 1 is used.