WO2020142029A1

WO2020142029A1 - Polyamide-based halogen free composite material

Info

Publication number: WO2020142029A1
Application number: PCT/TR2019/050879
Authority: WO
Inventors: Akin Isbilir; Lutfiye ALTAY; Yoldas SEKI; Mehmet SARIKANAT
Original assignee: Izmir Egitim Saglik Sanayi Yatirim A.S.
Priority date: 2018-12-31
Filing date: 2019-10-18
Publication date: 2020-07-09
Also published as: TR201821369A2

Abstract

The present invention is a polyamide-based composite material not including halogen and having flame retardant characteristic, wherein besides comprising organic phosphinate having specific proportion of phosphor, the subject matter composite material comprises one or more boron derivative material selected from colemanite, zinc borate, borax decahydrate and ulexite and having proportion between 1-15% by weight.

Description

POLYAMIDE-BASED HALOGEN FREE COMPOSITE MATERIAL

TECHNICAL FIELD

The present invention relates to a polyamide-based composite material not including halogen.

The present invention particularly relates to a polyamide-based composite material not including halogen and having flame retardant characteristic for usage in railways for the inner and outer parts of vehicles.

KNOWN STATE OF THE ART

Today, the usage proportion of thermoplastics among the synthetic polymers has reached to 65%. Polymers are mostly used in building and construction, transportation, electrical and electonic sectors and furniture and house goods and packaging sectors. Particularly polyamide (PA) based materials are increasingly used in transportation sector in the recent years in parts like brake hoses, socket boxes, battery boxes, oil cartels, buttons and handles.

However, polyamide is an easily flammable material. Polyamide is pyrollized at high temperatures and polyamide pyrollizing temperature critically depends on oxygen concentration. It is important that the products made of polyamide material have flame retardant characteristic. Therefore, in order to prevent easily burning of polyamide materials, flame retardant additives shall be added.

Aluminum hydroxide, magnesium hydroxide, bromides, organo-phosphors, antinomy- oxide chlorides are flame retardant materials. While mostly bromides are used in Asia, additives not including halogen are used in Europe and America. The compounds including halogen are very dangerous for humans, animals and environment. When flame redardant compounds including halogen is used, dangerous products like dioxine gas occurs in case of fire, and dioxine gas is a toxic gas. Legal regulations have been made in various countries, and the usage of these products has been delimited. Therefore, the request for flame retardants without halogen increases every passing day.

Polyamide 6 (PA6) is one of the thermoplastics which has application area in various fields like automotive, railway, textile, construction and electric-electronic sectors. PA6 has characteristics like relatively higher mechanical resistance and easily processability and high thermal resistance and good chemical resistance and good abrasion resistance and low friction coefficient. However, PA6s have some disadvantages like high humidity absorbance, low dimensional stability, low temperature impact resistance and easy flammability. Thus, by using some additives which improve the characteristics of pure PA6, these disadvantages can be eliminated. Particularly, PA6 is one of the thermoplastic materials which is easily flammable and which has low limiting oxygen index (LOI).

There are various standards for protection of railway vehicles from fire. For instance, according to standard EN 45545-2, the standards of the materials, having flame retardant characteristic and not including halogen and which can be used in the inner/outer applications of railway vehicles, have been defined at different HL1 , HL2 and HL3 danger levels. The material, which can be used at HL3 danger level, shall be V-0 according to UL94 burning standard, the limiting oxygen index (LOI) shall be greater than 32% according to EN ISO 4589-2: LOI standard, the fume density shall be smaller than 150 according to EN ISO 5659-3 standard and the fume toxicity shall be smaller than 0.75 according to NF X70-100-1 standard.

In the known state of the art, phosphor-based materials used as flame-retardant are disclosed.

In the patent application with number US2009030124, a polyamide-based composite material having flame retardant characteristic is disclosed. In said document, one or more phophinate and polymer structure combinations are disclosed as flame retardant. In the patent application with number CN106675007, a composition is disclosed comprising a phosphor-based flame retardant additive at a specific proportion together with polyamide 6.

Said composite materials are insufficient in providing high standards which are required particularly for use in railway vehicles.

As a result, because of all of the abovementioned problems and because of the insufficiency of the present solutions about the subject, an improvement is required in the related technical field.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a polyamide-based composite material with flame retardant characteristic and not including halogen, for meeting the above mentioned requirements and for eliminating the above mentioned disadvantages and for bringing new advantages to the related technical field.

The main object of the present invention is to provide a polyamide-based composite material which can be used in inner part/outer part of railway vehicles and not including halogen and having flame retardant characteristic.

An object of the present invention is to provide a polyamide-based composite material not including halogen and having flame retardant characteristic and which has high mechanical resistance and which can be easily processed and which has high thermal resistance and which has good chemical resistance and which has good abrasion resistance and low friction coefficient.

An object of the present invention is to provide a polyamide-based composite material which can be used at HL3 danger level according to EN 45545-2 standard in applications in inner part/outer part of railway vehicles.

Another object of the present invention is to provide a polyamide-based composite material which is within V-0 class according to UL94 burning standard. Another object of the present invention is to provide a polyamide-based composite material with limiting oxyen index greater than 32% according to EN ISO 4589-2 standard.

Another object of the present invention is to provide a polyamide-based composite material with fume density lower than 150 according to EN ISO 5659-3 standard.

Another object of the present invention is to provide a polyamide-based composite material with fume toxicity lower than 0.75 according to NF X70-100-1 standard.

The present invention moreover aims to provide a method for preparing a polyamide- based composite material which can be used in inner part/outer part of railway vehicles and not including halogen and having flame retardant characteristic.

In order to realize all of the abovementioned objects, polyamide-based composite material, not including halogen and having flame retardant characteristic, comprises one or more boron derivative material selected from colemanite, zinc borate, borax decahydrate and ulexite and having proportion between 1 -15% by weight, besides comprising organic phosphinate having specific proportion of phosphor.

The present invention moreover relates to a part with flame retardant characteristic and not including halogen in the inner part or outer part of the railway vehicle, for meeting the above mentioned requirements and for eliminating the above mentioned disadvantages and for bringing new advantages to the related technical field.

In order to realize all of the abovementioned objects, a polyamide-based composite material not including halogen and having flame retardant characteristic is provided. Said composite material comprises one or more boron derivative material selected from colemanite, zinc borate, borax decahydrate and ulexite and having proportion between 1 -15% by weight, besides comprising organic phosphinate having specific proportion of phosphor.

The present invention moreover relates to a method for preparing a polyamide-based composite material not including halogen and having flame retardant characteristic, for meeting the above mentioned requirements and for eliminating the above mentioned disadvantages and for bringing new advantages to the related technical field.

In order to realize all of the abovementioned objects, said method comprises the steps of mixing the other components to the molten polyamide and extruding the composite material at a specific temperature and turning said composite material into granule form.

The structural and characteristic properties and all advantages of the present invention will be understood in a more clear manner by means of the below mentioned detailed description and evaluation shall be made by taking into consideration the below mentioned detailed description.

DETAILED DESCRIPTION OF THE INVENTION

In this detailed description, the subject matter composite material is explained with references to examples without forming any restrictive effect only in order to make the subject more understandable.

The present invention describes a polyamide-based composite material not including halogen and having flame retardant characteristic.

The fire protection requirements in railway vehicles bring limitation to the characteristics of materials used in the inner and outer parts of the railway vehicles like inner surfaces, window frames, passenger seat coatings, inner and outer cable carriage channels and inner and outer coatings. The present invention discloses a polyamide-based composite material which provides the characteristics which are needed for usage in said railway vehicles.

The subject matter composite material comprises polyamide as the main component. Polyamide is a thermoplastic material. Since the limiting oxygen index (LOI) of polyamide is low, it is an easily flammable material. Said composite material preferably comprises polyamide 6 and/or polyamide 6.6. The reason of preferring polyamide 6 and/or polyamide 6.6 is that polyamide 6 and polyamide 6.6 have characteristics like relatively higher mechanical resistance and easily processability and high thermal resistance and good chemical resistance and good abrasion resistance and low friction coefficient.

The subject matter composite material comprises flame retardant additive. In the invention, organic phosphinate is used as flame retardant. Among the preferred organic phosphinates, diethyl phosphinic acid, aluminum diethyl-phosphinate and zinc phosphinate are provided. Together with organic phosphinates, melaine poly phosphate and its derivatives can be used together. Thus, protection is provided by forming a temperature-resistant layer. The used organic phosphinate can comprise phosphor with changing proportions. Thus, a suitable organic phosphinate is selected according to the amount of the needed active phosphor additive. For instance, the composite material can comprise organic phosphinate comprising phosphor at proportion of 15-25% by weight. The composite material preferably comprises one or more organic phosphinate selected from phosphor with proportion of 19-20% by weight, organic phosphinate comprising phosphor with proportion of 21 -22% by weight and organic phosphinate comprising phosphor with proportion of 23-24%. Since the phosphor proportion affects performance, the mixture shall be determined by taking into consideration the whole ingredient.

Said composite material comprises the minimum possible proportion of organic phosphinate since it is expensive and since it may deteriorate some characteristics like mechanical and physical characteristics. Moreover, processing difficulties like extrusion and injection may occur. In other words, when higher phosphor proportions are used for obtaining high LOI values, a product is formed with deteriorated mechanical characteristics and which is difficult to process, and as a result of this, the applicability decreases. For these reasons, the used organic phosphinate amount will show the desired performance and the phosphor proportion is determined according to the most suitable organic phosphinate.

The composite material preferably comprises one or more organic phosphinate selected from organic phosphinate comprising phosphor with proportion of 19-20% by weight, organic phosphinate comprising phosphor with proportion of 21 -22% by weight and organic phosphinate comprising phosphor with proportion of 23-24%, the total weight proportion of the used organic phosphinate is preferably 10-20%.

Boron products, which are mostly used in production of textile, glass fiber, agriculture and detergent, are also used as additive substance for roof coating materials, cellulosic isolation materials and cement. The subject matter composite material comprises boron-derivative materials as flame retardant additive. The boron derivative material preferably comprises zinc borate (2Zh0.3B2q3.3.5H2q) and/or coleminate (Ca2B60n.5H20). The boron-derivative material can also comprise one or more boron derivative material like borax decahydrate, ulexite together with coleminate and/or zinc borate and/or instead of coleminate and/or zinc borate. It has been found that, by means of the present invention, the flame retardancy characteristics and the limiting oxygen index of the subject matter composite material increase in a synergistic manner by means of combined usage of organic phosphinate with coleminate or zinc borate or borax decahydrate or ulexite, which are substantially rich in terms of mineral, or another boron derivative material. Said composite material preferably comprises colemanite between 0.1 % and 15% by total weight and one or more of zinc borate, ulexite, borax decahydrate between 0.1 % and 15% by weight.

The subject matter composite material moreover can comprise one or more of the fume suppressor fillings. The preferred fume suppressors are siloxane-based fume suppressors. Among the preferred siloxane-based fume suppressors, there is high molecular weighted siloxane with polypropylene (PP) carrier in terms of the enclosure of fume and performance of decreasing release of fume to the outer medium. Said composite material comprises siloxane-based fume suppressor at proportion between 1 -5% by total weight. Preferably the proportion of siloxane-based fume suppressor is between 1 -3% by total weight and more preferably, it is 1 , 3 or 5% by total weight. When the proportion of the siloxane-based fume suppressor is greater than the mentioned proportions, the burning and other characteristics of the composite material can deteriorate.

The subject matter composite material can comprise other flame retardant additives and fume suppressing additives. Said composite material preferably comprises magnesium hydroxide and/or boehmite. Magnesium hydroxide used at low proportion is functioning as a fume suppressor. In the subject matter composite material, magnesium hydroxide is preferably used as fume suppressor.

It has been found that the components used in the subject matter composite material create synergistic effect and increase the flame retardancy value of the polyamid material and increase the limiting oxygen index (LOI) and decrease fume density and fume toxicity. Since one or more of boron derivative materials like colemanite, zinc borate, ulexite, borax decahydrate, and fume suppressor is used together with organic phosphinate; a polyamide-based composite material is obtained which can be used at HL3 danger level and in other words, which is V-0 according to UL94 burning standard and where the limiting oxygen index is greater than 32% according to EN ISO 4589-2: LOI and where fume density is smaller than 150 according to standard EN ISO 5659-3 and where the fume toxicity is smaller than 0.75 according to standard NF X70-100-1. Moreover, it has been found that the mechanical characteristics of the obtained composite material do not worsen when compared with the mechanical characteristics of raw polymer.

The subject matter composite material can moreover comprise glass fiber as reinforcement. The usage of glass fiber as reinforcement provides improvement of the mechanical characteristics of the subject matter composite material like drawing and bending resistance and the increase of the softening temperature of the material. Addition of glass fiber as reinforcement to said composite material affects the non flammability characteristics of the composite material. Therefore, the amount of added glass fiber shall be optimized according to the proportions of the other components. The composite material comprises glass fiber at proportion between 10- 40% by total weight.

While the subject matter composite material is being produced, double-screw extruder is used. In said extruder, there are four gravimetric feeders. During production step, polyamide is given from the feeder with number one. When required, process adjuvants are given, for instance the inner and outer lubricants are given from the feeder with number two. Boron derivative materials like organic phosphinate, colemanite, zinc borate, ulexite, borax decahydrate, and magnesium hydroxide and siloxane-based fume suppressor are added from the feeder with number three. In order to distribute said additives into the polymer in a homogeneous manner, feeding points can be changed. For instance, said additives can be also given from the feeders with numbers two and/or four.

Glass fiber is fed from the feeder with number four during production of reinforced composite. The additive and reinforcements may not mix homogeneously in the extruder process. Accordingly, this problem can be solved by making improvement in the screw design of the extruder. Moreover, in order to provide homogeneous distribution, the wax amount for polyamide can be raised to proportion of for instance 1 %. Moreover, in case the obtained composite material is not suitable for injection molding method, chain breakers can be added to the medium for reducing polyamide viscosity. The pasta, exiting the extruder and having diameter of for instance 3 mm, is cut in the strand type pellet machine and is turned into granule form.

Claims

1. A polyamide-based composite material not including halogen and having flame retardant characteristic, wherein besides comprising organic phosphinate having specific proportion of phosphor, the subject matter composite material comprises one or more boron derivative material selected from colemanite, zinc borate, borax decahydrate and ulexite and having proportion between 1 -15% by weight.

2. The composite material according to claim 1 , wherein said boron-derivative material is coleminate or zinc borate.

3. The composite material according to claim 1 , wherein spesific proportion of magnesium hydroxide is provided as fume suppressor.

4. The composite material according to claim 1 , wherein siloxan-based fume suppressor is provided with proportion between 1 -5% by weight.

5. The composite material according to claim 4, wherein the proportion of said siloxan-based fume suppressor is 1 %, 3% or 5% by weight.

6. The composite material according to any one of the preceding claims, wherein said polyamide is polyamide 6 and/or polyamide 6.6.

7. The composite material according to any one of the preceding claims, wherein the subject matter composite material comprises one or more organic phosphinate selected from phosphor with proportion of 15-25% by weight, organic phosphinate selected from phosphor with proportion of 19-20% by weight, organic phosphinate comprising phosphor with proportion of 21 -22% by weight and organic phosphinate comprising phosphor with proportion of 23- 24%.

8. The composite material according to claim 7, wherein the total organic phosphinate proportion is between 10-20% by weight.

9. The composite material according to any one of the preceding claims, wherein glass fiber is provided.

10.The composite material according to claim 9, wherein said glass fiber proportion is between 10-40% by weight.

11. The composite material according to any one of the preceding claims, wherein inner and/or outer lubricant is/are moreover provided.

12.The composite material according to any one of the preceding claims, wherein said composite material is suitable for being shaped by means of injection and extrusion method.

13. A part not including halogen and having flame retardant characteristic, at the inner section or the outer section of the railway vehicle, wherein a composite material is provided which is suitable to claims between 1 and 12.

14. A method for preparing composite material according to any one of the claims between 1 and 12, wherein the following steps are provided:

- mixing the other components to the molten polyamide and

- extruding the composite material at a specific temperature and turning said composite material into granule form.