Flame retardant polymer composition

 

(57) Abstract:

The invention relates to compositions based on macromolecular compounds, in particular polyamide composition used for obtaining a flame-retardant polymeric materials, and can be used in electrical engineering, transport engineering. Describes a new flame retardant polymer composition comprising a polyamide and a filler, based on the silicate material. The composition contains as filler carbon-aluminosilicate material, which is a mixture of natural carbon and silicate, taken in the ratio of from 10:90 to 20:80, respectively, and further comprises an additive sodium salt of stearic acid or aminosilane in the following ratio, wt.%: carbon-aluminosilicate material 10-50, the additive is 0.1 to 5.0, polyamide - rest. The technical result improved quality polymer products. The polymer products obtained on the basis of the proposed compositions are flame retardant (V = 0 for VL-94; Kg= 0,03-0,1), have high impact strength values (U = 1,57 is 1.70 kJ/m) and the deformation resistance (D > 100°C) and characterized by the absence dropping. table 2.

From the way, used to obtain a flame-retardant polymeric materials, and can be used in electrical engineering, transport engineering, etc.

One of the main problems of polymeric materials is the problem of production of plastic products, which, as the fire was kept sufficiently high physical-mechanical properties under extreme thermal loads [Fillers for polymer composites. Ed. by G. S. Katz and D. C. Malevsky, M., Chemistry, 1981, S. 76] [1].

Known polyamide composition with improved mechanical and dielectric properties for the manufacture of casings of appliances [Japan, the application 1-213356, C 08 L 77/00, C 08 K 3/22, publ. 28.08.89] [2].

The composition comprises 5-40 (10-20)% of polyamide (PA) and 60-95 (80-90)% of the flame retardant powder of magnesium oxide (MgO), in which the fraction of particles with an average diameter of 0.5-70 (2-25 microns) is > 90 (> 95)%. The composition is prepared by thorough mixing of the melt of the polyamide in a twin-screw extruder at 280oC flame retardant powder of magnesium oxide. From the resulting mass by injection molding to form patterns. The resulting polymer material is fire resistant: fire on VL-94. The speed and spread of the l based on the composition [2] is characterized by the following indicators: impact strength Izod (U) is equal to U = 1,41 kJ/m, deformation resistance under load 1,82 MPa (D) D = 64oC. Start dropping material is observed at T = 280oC, i.e., when the melting point of the polyamide.

Known composition with reduced Flammability [Czechoslovakia, A. S. N 266515, class C 08 L 77/00, publ. 13.07.90] [3] consists of a polyamide filler-flame retardant and additives. As filler composition comprises 30-70% of a half-baked hydrated dolomite with a particle size of < 30 μm, and as an additive to 5% of fatty acids (C12- C22and/or their esters with polyhydric alcohols.

The composition is obtained by introducing into the melt of the polyamide flame retardant and additives. From the mixture obtained form the samples. The polymeric material obtained from the composition [3], refers to fire-rate: Flammability Kg= 0.25, the resistance according to VL-94 V = 0 c.

As shown by our studies, physico-mechanical characteristics and start dropping polymeric material have the following parameters: U = 1.35 kJ/m; D = 62oC; T = 280oC, respectively.

Also known polyamide composition containing 60 to 80% polyamide and as a filler - flame retardant - 20 - 40% of finely ground calcined aluminium silicate with razmara the receiving composition pre-silicate of aluminum appreciat aminosilanes, and then injected into the melt of the polyamide. From the resulting mass by injection molding to obtain samples.

As with the previous polymer products [2] and [3], this polymeric material [4] is characterized by high resistance: V = 0 for VL-94 and Kg= 0,15.

The values of impact strength Izod, deformation resistance and the temperature started dropping, according to our data, reach values U = 1,37 kJ/m; D = 66oC; T = 280oC, respectively.

From the analysis of the characteristics of a polymeric material on the basis of known compositions [2, 3, and 4] it follows that these polyamide compositions provide a sufficiently high resistance products.

However, the resulting a (fairly) low values of impact strength Izod (U), the deformation resistance under load 1,82 MPa (D) and the temperature started dropping (T) indicate the loss of a polymeric material physical and mechanical properties under extreme thermal loads, for example the fire: the polymer begins to melt, which is accompanied by change in the shape of a product and a sharp decrease in strength.

Closest to the invention to the technical essence and the achieved result is (nonflammable) ogna composition contains a 70-30 g thermoplastic with IR 0.2 to 10 g/min (polyethylene (PE), polypropylene (PP), polyamide (PA-6) and others); and the filler is a flame retardant composition contains 30 to 70 g of magnesium hydroxide with an average particle size of 0.6 - 0,008 μm and 0.5 to 15 g of synthetic silicate containing 40 to 70% SiO2, 10-45% of a mixture of MgO and CaO.

The composition is prepared as follows. Pre-receive silicate by heat treatment under pressure (autoclave) of a mixture of silicates, silicon, magnesium and calcium. The resulting product, after cooling, crushed and milled to obtain a particle size of no more than 20 microns, and then mixed with a powder of magnesium hydroxide. The mixture of the flame retardant is introduced into the molten thermoplastic. From the resulting composition by the method of injection molding is prepared polymer products. The polymeric material obtained by us-based thermoplastic is a polyamide PA-6, is characterized by high resistance: V = 0 c VL-94 and Kg= 0,15, as confirmed by the data presented in [5]. There were also defines the fundamental characteristics of the material, as impact strength Izod, deformation resistance and the temperature started dropping, the values of which are: U = 154 kJ/m; D = 78oC; T = 280oC, respectively.

The main drawback of fire and physico-mechanical characteristics. The polymer product can not withstand the extreme thermal loads: at temperatures above 280oC melt, lose their shape, strength.

The basis of the invention is tasked to improve the flame-retardant polyamide composition through the use of filler - flame retardant rational composition with regard to thermo-physical characteristics of the components of the filler, thereby improving the quality of the material on the basis of the offered polyamide composition by eliminating dropping, increase toughness and deformation resistance in conditions of long-term thermal loads while achieving consistently high fire resistance.

To achieve the objectives of the proposed polymer composition based on polyamide, including the filler, which according to the invention additionally contains an additive, and as a filler - carbon-aluminosilicate material, and the components are taken in the following ratio (wt.%):

Carbon-aluminosilicate material - 10 - 50

The additive is 0.1 to 5.0

Polyamide - Rest

Moreover, the carbon-aluminosilicate material contains natural carbon and silicate in the following ratio of Komponente in flame retardant polymer compositions fillers-retardants are materials, which have a high percentage of weight loss within the temperature degradation of the polymer matrix. This does not affect thermal and thermal properties of the polymer, i.e. the properties of the polymer composition determined by the above-mentioned properties of the polymer.

The presence in the inventive polymer compositions of filler-flame retardant in the form of carbon-aluminosilicate material provides, we believe, the elimination of recovety of heat transfer by weight of the composition, thereby improving the effect of carbonization of the organic part of the composition and linking the main part of the polymer matrix on the surface of the inventive filler. And, therefore, the obtained polymer composition takes on the properties of thermal stability of the filler. The identified effect is a new, non-traditional, which effectively solves the problem of improving the quality of products based flame retardant polymeric compositions: fire-resistant polymer material (V = 0 c VL-94; Kg= 0,03 - 0,1); has high physical and mechanical properties (impact strength Izod equal to U = 1,57 is 1.70 kJ/m; deformation resistance under load 1,82 MPa D more than 100oC) and is characterized by the absence of tablepad otomat filler - carbon-aluminosilicate material. In a mixer put the silicate with a particle size of not more than 40 μm and natural carbon with a particle size of not more than 5 μm. As aluminosilicate take kaolin [GOST 19609.0-89] or glauconite [THE-21-25-194-86] , or halloysite [THE-21-25-194-86], and as a natural carbon - colloidal graphite [OST 6-08-431-75] or shungite [OST 6-08-431-75]. The mixing of these components should be performed within 10 - 20 minutes

The aluminosilicate and natural graphite taken in amounts that provide the claimed ratio of components in the filler (wt.%):

Natural carbon - 10 - 20

The aluminosilicate - 80 - 90

In the thus prepared filler injected additive, which is used as the sodium salt of stearic acid (GOST 5821-89] or aminosilane [TU-38-103211 - 89], stirred over time, providing a homogeneous powder; then in a twin-screw extruder carefully mix the resulting powder filler and additives with the molten polyamide is PA-6 [THE-6-05-964-89]; PA-6/12 [THE-6-05-1011-89]; PA 66/6 [THE-6-05-408-89]. The additive can be injected directly into the extruder at the feed to the melt of the polyamide powder filler. The estimated number of components ensures that the claimed composition (wt.%):

The main indicators of quality polymer material:

- physico-chemical characteristics:

- fire; this property is characterized by two indicators:

- coefficient Flammability, Kg[GOST 12.1.044-84]

- the speed of flame propagation V c VL-94 [ASTM D2115]

the temperature started dropping ToC [GOST 12.1.044-89]

- physico-mechanical characteristics:

- impact strength Izod [U], kJ/m [GOST 11529-86]

deformation resistance [D]oC [ASTM D 256; ASTM D 2115].

An example implementation of the invention

To obtain a filler - carbon-aluminosilicate material in the mixer load of 20 g of kaolin with a particle size of not more than 40 μm and 5 g of colloidal graphite with a particle size of not more than 5 μm, the mixture is stirred for 15 minutes, the Obtained filler of the following composition (wt.%):

Colloidal graphite - 20

Kaolin - 80

In the extruder place of 74 g of the polyamide (PA-6), melted at a temperature of 280oC and injected with 25 g of the obtained filler and 1 g of sodium salt of stearic acid. Components are mixed to obtain a homogeneous mass. The obtained polyamide composition corresponds to the composition (wt.%):

Carbon-alumosilicates plate, the main characteristics of the polymer material are shown in table 1, example 2.

The obtained flame-retardant polymeric material (V = 0 for VL - 94 and Kg= 0,05) with high physical-mechanical properties (U = 1.65 kJ/m; D > 100oC) that does not have calipatria.

Table 1 shows the compositions of the polymer compositions obtained by using the polyamide and additives having different nature, and containing the filler is carbon-aluminosilicate material, the number of which is in the claimed range and beyond.

It is established that the quantitative and qualitative composition of the polymeric composition selected from the conditions providing high quality products: the product has high values ognisanti and physico-mechanical properties, characterized by the absence dropping (table 1, examples 1-13).

With exorbitant decrease in the content of filler and additives, possible with exorbitant increase in the concentration of polyamide in the composition, i.e., when the carbon-aluminosilicate filler is not enough for structuring the entire weight of the polymer, the composition does not ensure high quality of the obtained polymer is (C).

This leads to deformation of the product and the manifestation of the effect of dropping already at the melting temperature of the polyamide (T = 280oC) (table 1, example 14).

When the exorbitant increase in the content of filler and additives, possible with exorbitant decrease in the content of the polyamide in the composition, it is impossible to carry out the homogenization of the powder components with molten polyamide in the extruder, which then causes a decrease in the quality polyamide products on the basis of such composition: all performance worsens and reaches almost the level of the known technical solutions (table 1, example 15).

Use in polyamide compositions as a filler of carbon-aluminosilicate material of the inventive composition, imparts thermophysical properties, providing a flame-retardant polymeric products with high physical-mechanical characteristics and lack dropping (table 2, examples 1-8).

In conditions of high content in the filler of aluminum silicate (kaolin) (table 2, example 9) or natural carbon (colloidal graphite) (table 2, example 10) the use of such compositions in the polymer composition leads to a change of the coefficient of t is una prototype.

The advantages of the proposed flame-retardant polymer composition as compared with the known are the following:

qualitative and quantitative composition the proposed composition, taking into account the proposed composition of the filler provides the flame-retardant polymeric products with high physical-mechanical properties:

- the speed of flame propagation V = 0 for VL-94;

- coefficient Flammability Kg= 0,03 - 0,1;

- impact strength Izod U = 1,57 is 1.70 kJ/m;

deformation resistance under load 1,82 MPa D > 100oC;

- no calipatria until fracture of the specimen.

The obtained values of physico-chemical and physico-mechanical properties of polymer products based on the proposed composition evidence of the preservation of physico-chemical and physico-mechanical properties of the products in extreme conditions, for example in case of fire.

The advantage of the proposed composition is to reduce the cost of the obtained polymer products, energy savings and improvement of the ecological situation in production.

Flame retardant polymer composition comprising a polyamide and a filler on the basis of silicate material, featuring the camping natural carbon and silicate, taken in a ratio of from 10 : 90 to 20 : 80, respectively, and further comprises an additive sodium salt of stearic acid or aminosilane in the following ratio, wt.%:

Carbon-aluminosilicate material - 10 - 50

The additive is 0.1 to 5.0

Polyamide - Rest

 

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