PL221850B1 - Method for producing elastomer composite with flame retardant - Google Patents

Description

The subject of the invention is a method of producing a flame retardant elastomer composite from synthetic or natural rubber or a mixture thereof.

Elastomers, due to their unique properties, which include, first of all, the ability to significant reversible deformations and to damp vibrations, accompanied by low specific weight, moderate cost and ease of processing, are widely used for the production of seals, flexible covers and damping elements. vibrations, in transport and automotive, machinery and mining industries, including mining. Numerous applications, also in fire hazard conditions, for example in mines, are the reason for the search for methods of flame retardant elastomeric materials. Only a few elastomers, such as plasticized polyvinyl chloride, chlorosulfonated polyethylene or fluorine rubber, are non-flammable due to their chemical structure.

In order to obtain non-flammable or flame-retardant elastomeric materials, flame retardants are introduced into rubber mixtures, the action of which consists in interrupting or limiting the access of oxygen to the fire zone, absorption of heat generated during combustion or the production of non-flammable gases, e.g. water vapor, which additionally reduces temperature of the tested system. Antipyires can act physically (by cooling, creating a protective layer on the surface of the combusted material, diluting flammable gases) or chemically (through reactions accompanying solid or gas combustion). Some of these effects can add up, which is known as a synergistic effect.

There is a well-known method of reducing the flammability of polymeric materials based on epoxy resins, unsaturated polyesters, polyethylene or polyvinyl chloride by introducing aluminum hydroxide into them. However, a significant reduction in flammability is achieved only after the introduction of large amounts of it, which in turn negatively affects the mechanical properties of the materials. The flame-retardant effect of aluminum hydroxide is described, among others, by in the journal Plastics Additives & Compounding 2003, 5, 18.

There is also a known method of reducing the flammability of polymeric materials by introducing into them compounds of fluorine, boron or chlorine, for example cheap and easy to process chloroparaffin with a degree of chlorination of 40-70%. The products of the thermal decomposition of chloroparaffin are more volatile and therefore the effectiveness of its flame retardant action is lower than that of fluoro or organo boron compounds. However, the general disadvantage of organohalogen compounds is the toxicity of the released products of their thermal decomposition and the dripping when burning, which facilitates the spread of the flame.

The synergistic effect of chloroparaffin and antimony trioxide is also well known. Antimony trioxide itself can be introduced into polyvinyl chloride, where it reacts with chlorine present in the polymer to form stable antimony halides.

There is also a known method of improving the thermal stability of high-density polyethylene (PE-HD) by incorporating paraffin, chloroparaffin, antimony trioxide, and expanded graphite into the polymer, as described in the Energy Conversion and Mangement 2010, 51, 2733 journal.

It is known to use expandable graphite, also known as expanding, as a component of non-flammable fire-resistant plastics. Expandable graphite is a new barrier flame retardant, in which graphite layers, most often intercalated with sulfuric (VI) acid, nitric (V) or acetic acid, are pulled apart, resulting in an increase in the volume of the material, which can reach up to 250 times the initial value. The type of acid used determines the starting temperature of the expansion process. The expandable graphite can be used alone or simultaneously with another flame retardant, most often zinc borate or poly (ammonium phosphate).

Thus, in the patent application US 8178449 the use of expandable graphite in the production of non-flammable roofing coatings is described.

From the journal Polymer Degradation and Stability 2005, 89, 70 there is known a method of improving the thermal properties of polyamide 6-based nanocomposites by incorporating therein in an amount of 1-5% by weight of expandable graphite.

In turn, Polymer Degradation and Stability 2002, 77, 195 shows the use of expandable graphite alone or in combination with ammonium triethylphosphate in order to improve thermal stability and reduce the flammability of poly (isocyanine-polyurethane) foams.

PL 221 850 B1

The journal Polymer Degradation and Stability 2011, 96, 183 describes the synergistic effect of expandable graphite and poly (ammonium phosphate as a flame retardant in polylactide composites).

In contrast, the journal Polymer Degradation and Stability 2001, 71, 375 describes the interaction of expandable graphite with poly (ammonium phosphate), zinc borate, NP28 phosphorous compound or microencapsulated red phosphorus as a flame retardant in low density polyethylene (PE-LD) or ethylene copolymer with vinyl acetate (EVA).

Expandable graphite also works synergistically with magnesium hydroxide as a flame retardant for poly (propylene composites, as reported in Polymer Engineering and Science 2007, 47, 1756, or ethylene vinyl acetate) to reduce its flammability, as reported in Polymer Degradation and Stability 2003, 81, 401.

There are also known methods of improving the dispersion of expandable graphite in polyurethane foams by encapsulation and simultaneous modification of graphite particles with poly (methyl methacrylate), which prevents the release of gases expanding graphite and at the same time contributes to the improvement of its miscibility with the polymer matrix. Such modification leads to a reduction in the flammability of polyurethane foams, and also composites containing unmodified expandable graphite exhibit flame retardancy, as described in the journal Polymer Degradation and Stability 2009, 94, 971.

A method of producing a flame-retardant elastomer composite from synthetic natural rubber or a mixture thereof, which consists in preparing an elastomeric blend containing rubber or a mixture of rubbers, sulfur or dicumyl peroxide, antioxidant, sulfur vulcanization accelerators, preferably in the form of tetramethylthiuram disulfide, N-cyclohexyl-2-cyclohexyl benzothiazolylsulfenamide and N-isopropyl-N-phenyl-p-phenylenediamine or zinc ethylphenyldithiocarbamate, silica, stearin, zinc oxide and antipyrins, including expandable graphite intercalated with an inorganic acid, preferably sulfuric acid (VI), and then heating the elastomeric mixture temperature and time determined on the basis of volkametric measurements, according to the invention, it is characterized in that the antipyrins used are, in addition to expandable graphite, with an expansion degree of 150-350 ml / g, preferably 250 ml / g, and an expansion start temperature of 150-250 ° C, preferably e 200 ° C, acid intercalated, used in an amount of 10-60, preferably 30, parts by weight / 100 parts by weight of rubber, also aluminum hydroxide in an amount of 15-90, preferably 30, parts by weight / 100 parts by weight of rubber and chloroparaffin with a chlorine content 40 or 70%, in an amount of 5-30, preferably 15, parts by weight / 100 parts by weight of rubber.

The process of the invention is illustrated by the following examples.

P r z k ł a d 1

A rubber blend was prepared containing in parts by weight: styrene-butadiene rubber (SBR) by Ker 1500 (Syntos, Poland), silicas (Arsil, Degussa, Germany), stearin of zinc oxide technical (ZnO), triethanolamine, antioxidant Polnox R N-isopropyl-N-phenyl- p-phenylenediamine tetramethylthiuram disulfide N-cyclohexyl-2-benzothiazolylsulfenamide sulfur aluminum hydroxide (Martinal OL-107, Martinswerk GmbH, Germany) chloroparaffin with a content of Cl 70% by weight (Chlorez 700, ICC Industrie-Dover, UK) expandable graphite expansion of 250 ml / g and an expansion start temperature of 200 ° C, intercalated with acid (Nord-Min 251, Nordmann Rassmann, Germany)

A mix was also prepared in which natural rubber (NR, RSSII) was used instead of SBR, and a mix in which, instead of SBR, a mixture of SBR and NR with a weight ratio of 40/60 components was used.

- 100 parts,

- 40 parts,

- 1 part,

- 3.5 parts,

- 4 parts,

- 2 parts,

- 2 parts,

- 0.2 parts,

- 1.4 parts,

- 1.2 parts,

- 30 parts,

- 15 parts,

- 30 parts.

PL 221 850 B1

- 100 parts,

- 40 parts,

- 1 part,

- 5 parts,

- 4 parts,

- 1 part,

- 0.5 parts,

- 1.5 parts,

- 1.5 parts,

- 0.5 parts,

- 30 parts,

- 15 parts,

The prepared mixtures were pressed under pressure in a steel mold, heated to the temperature of 433K, for 20 min (SBR), 30 min (SBR / NR) and 5 min (NR).

Then, the flammability of SBR vulcanizates was determined in 3 independent laboratories (Institute of Polymers and Dyes Technology of the Lodz University of Technology, Central Mining Institute in Katowice and the Institute of Polymer Materials and Dyes Engineering in Poznań). It was found that the obtained vulcanizate is characterized by the oxygen index Ol = 35.2-35.8%, which proves its non-flammability.

In the case of the SBR / NR vulcanizate, the value of the oxygen index was equal to 30.1%, which also proved its non-flammability, while for the NR vulcanizate, the oxygen index was 27.8%, which is on the borderline between non-flammable and slow-burning material.

P r z o f e 2

A mixture was prepared with the following composition in parts by weight:

acrylonitrile-butadiene rubber (NBR) by Nipol N41 (ZEON Corp. Japan) silica (Arsil, Degussa, Germany) technical stearin

ZnO ethylene glycol antioxidant Polnox R ethylphenyldithiocarbamate zinc disulfide tetramethylthiuram N-cyclohexyl-2-benzothiazolylsulfenamide sulfur aluminum hydroxide (Martina OL-107, Martinswerk GMbH Germany) chloroparaffins with a content of Clustrorez-700% by weight (ChoverClCl. expanded graphite with an expansion rate of 250 ml / g and an expansion temperature of 200 ° C, intercalated with acid (Nord-Min 251, Nordmann Rassmann, Germany)

The prepared mix was pressed under pressure in a steel press heated to the temperature of 433K, for 15 minutes.

Then, the flammability determinations were made, which showed that the tested material was non-flammable (Ol = 32.7%).

P r z o f e 3

A mixture was prepared containing in parts by weight:

Keltan 2340 ethylene propylene diene rubber (EPDM) (Brenntag Grouo, UK) silica (Arsil, Degussa, Germany) technical stearin

ZnO, triethanolamine, dicumyl peroxide, aluminum hydroxide (Martina OL-107, Martinswerk GmbH, Germany), chloroparaffins with a Cl content of 70% by weight (Chlorez 700, ICC Industrie-Dover, UK), expandable graphite with an expansion degree of 250 ml / g and an expansion temperature of 200 ° C, acid intercalated (Nord_min 251, Nordmann Rassmann, Germany)

The prepared mixture was pressed under pressure in a steel press heated to the temperature of 433K, for 30 minutes.

The oxygen index of the vulcanizate was 31.6%, which proved that the EPDM vulcanizate is non-flammable.

- 30 parts.

- 100 parts,

- 40 parts,

- 1 part,

- 5 parts,

- 4 parts,

- 0.6 parts,

- 30 parts,

- 15 parts,

- 30 parts.

PL 221 850 B1

Example 4

For comparative purposes, mixtures with the following compositions were prepared in parts by weight:

Ker 1500 SBR (Syntos, Poland) - 100 parts, silica (Arsil, Degussa, Germany) - 40 parts, technical stearin - 1 part,

ZnO - 3.5 parts, triethanolamine - 4 parts, antioxidant Polnox R - 2 parts,

N-isopropyl-N-phenyl-p-phenylenediamine - 2 parts, tetramethylthiuram disulfide - 0.2 parts,

N-cyclohexyl-2-benzothiazolylsulfenamide - 1.4 parts, sulfur - 1.2 parts.

A mix was also prepared in which natural rubber (NR, RSSII) was used instead of SBR, and a mix in which, instead of SBR, a mixture of SBR and NR with a weight ratio of 40/60 components was used.

Mixes after pressing in conditions as in the example, which proved their flammability;

NBR brand Nipol N41 (ZEON Corp., Japan) silica (Arsil, Degussa, Germany) technical stearin zinc oxide (ZnO) ethylene glycol antioxidant Polnox R ethyl phenyl dithiocarbamate zinc disulfide tetramethylthiuram

Sulfur N-cyclohexyl-2-benzothiazolylsulfenamide, which after pressing in the conditions as in Example 1, which indicated its flammability;

Ker 1500 SBR (Syntos, Poland) silica (Arsil, Degussa, Germany) technical stearin zinc oxide (ZnO) triethanolamine antioxidant Polnox R

N-isopropyl-N-phenyl-p-phenylenediamine tetramethylthiuram disulfide

N-cyclohexyl-2-benzothiazolylsulfenamide sulfur aluminum hydroxide (Martinal OL-107, Martinswerk GmbH, Germany) chloroparaffins with a Cl content of 70% by weight (Chlorez 700, ICC Industrie-Dover, UK) which after pressing under the conditions of example 1 which testified to its flammability;

Ker 1500 SBR (Syntos, Poland) silica (Arsil, Degussa, Germany) technical stearin zinc oxide (ZnO) triethanolamine antioxidant Polnox R

N-isopropyl-N-phenyl-p-phenylenediamine tetramethylthiuram disulfide

Sulfur N-cyclohexyl-2-benzothiazolylsulfenamide was characterized by O1 = 19.4%,

- 100 parts,

- 40 parts,

- 1 part,

- 5 parts,

- 4 parts,

- 1 part,

- 0.5 parts,

- 1.5 parts,

- 1.5 parts,

- 0.5 parts, it was characterized by Ol = 21.1%,

- 100 parts,

- 40 parts,

- 1 part,

- 3.5 parts,

- 4 parts,

- 2 parts,

- 2 parts,

- 0.2 parts,

- 1.4 parts,

- 1.2 parts,

- 60 parts,

- 15 parts, characterized by Ol = 22.2%,

- 100 parts,

- 40 parts,

- 1 part,

- 3.5 parts,

- 4 parts,

- 2 parts,

- 2 parts,

- 0.2 parts,

- 1.4 parts,

- 1.2 parts,

PL 221 850 B1 of expandable graphite with an expansion rate of 150 ml / g and an expansion temperature of 200 ° C, intercalated with acid (Nord-Min 251, Nordmann Rassmann, Germany) - 30 parts, which after pressing in the conditions as in example 1 was characterized by 01 = 21.9%, which proved that adding only expandable graphite did not cause the composite non-flammability.

Based on a comparative analysis of photos taken with a high-resolution scanning electron microscope (SEM) of a cross-linked styrene-butadiene rubber mixture containing only expandable graphite and a mixture containing aluminum hydroxide, chloroparaffin and expandable graphite, it was found that the simultaneous use of expandable graphite, better aluminum hydroxide and lead to aluminum hydroxide. dispersion of large particles of expandable graphite in an elastomer matrix. This allows the graphite plates of the expandable graphite to exhibit a fully barrier flame retardant mechanism.

Claims (1)

A method of producing a flame-retardant elastomer composite from synthetic natural rubber or a mixture thereof, which consists in preparing an elastomeric blend containing rubber or a mixture of rubbers, sulfur or dicumyl peroxide, antioxidant, sulfur vulcanization accelerators, preferably in the form of tetramethylthiuram disulfide, N-cyclohexyl-2-cyclohexyl benzothiazolylsulfenamide and N-isopropyl-N-phenyl-p-phenylenediamine or zinc ethylphenyldithiocarbamate, silica, stearin, zinc oxide and antipyrines, including expandable graphite intercalated with an inorganic acid, preferably sulfuric acid (VI), and then heating the elastomeric mixture temperature and time determined on the basis of volkametric measurements, characterized in that the antipyrins used are, in addition to expandable graphite, with an expansion degree of 150-350 ml / g, preferably 250 ml / g, and an expansion temperature of 150-250 ° C, preferably 200 ° C, intercalated k wasem, used in an amount of 10-60, preferably 30, parts by weight / 100 parts by weight of rubber, also aluminum hydroxide in an amount of 15-90, preferably 30, parts by weight / 100 parts by weight of rubber and chloroparaffin with a chlorine content of 40 or 70%, in amounts of 5-30, preferably 15, parts by weight / 100 parts by weight of rubber.