Research and development of new fireproof steel-plastic composite panel and its halogen-free flame retardant core layer material

Research and development of new fireproof steel-plastic composite panel and its halogen-free flame retardant core layer material

Abstract: This paper mainly studies the preparation technology and technical performance test of new fire-resistant steel-plastic composite board materials, and evaluates and analyzes its combustion performance and physical and mechanical properties from the test results. Therefore, it has certain guiding significance for the selection of fire-resistant steel-plastic composite board materials in building decoration.

Key words: steel-plastic composite board; Aluminum-plastic composite board; Fire safety; Performance evaluation; SBI test; GB 8624, GB/T17748,

1、 Preface

With the continuous improvement of the national economic level and people's awareness of fire safety, especially the occurrence of major fire incidents caused by external insulation and decoration materials for building exterior walls in recent years, steel plastic composite decorative panel materials have received increasing attention from the building decoration industry and various sectors of society. Therefore, the research and development of steel plastic composite decorative materials and the evaluation and analysis of fire safety performance are becoming more and more in-depth. The successful development of a new type of fire-resistant steel plastic composite board and its high flame retardant core material has greatly improved the fire resistance of buildings, making it a new type of fire-resistant and environmentally friendly decorative material.

Fireproof steel plastic composite board (hereinafter referred to as steel plastic composite board) is a new type of building material decoration product that uses high-quality stainless steel or galvanized alloy steel coated board as the upper and lower panels, and halogen-free flame-retardant plastic as the core material. Fireproof steel plastic composite board not only maintains the good physical and mechanical properties of ordinary steel plastic board, but also has excellent fire resistance performance, meeting the relevant international classification standards for fire resistance building materials. It emits little smoke and is an environmentally friendly green building material. Currently, it has been promoted and used in the field of building interior and exterior wall decoration and other application areas.

2、 Technical principles for the development of fire-resistant steel plastic composite panels

Fireproof steel plastic board is an environmentally friendly (non-toxic and pollution-free) and resource-saving (can save more than 60% of basic resin) flame-retardant and safe material. This technology project uses non-toxic and pollution-free environmentally friendly flame retardants (filled with more than 70%) to flame retardant modified polyethylene base resins. It is developed through core technologies such as flame retardant polymerization coating activation technology, halogen-free flame retardant compounding efficiency enhancement technology, and graft copolymerization modified compatibilizers.

1. Technical key and difficult points
The technical purpose of developing fire-resistant steel plastic composite panels is to maintain other properties of the steel plastic composite panels and have good physical and mechanical properties while achieving the fire rating; The technical key is the formulation development of low smoke halogen-free high flame retardant core materials and the adjustment and coordination of extrusion composite production process technical parameters; The technical difficulty is to meet the process requirements of the steel plastic plate continuous hot pressing composite production line, with good processing and forming performance and drum peeling strength.

We attach great importance to achieving breakthroughs in the following aspects in the research of high flame retardant steel plastic composite board core material technology:

1.1. Optimize the cost of high flame retardant core materials

At present, the price of high flame retardant steel plastic sheet is about 25-35 yuan/M2 higher than that of ordinary steel plastic sheet, with an increase of about 15% -25%, mainly due to the cost of the core material of high flame retardant steel plastic sheet. In our research, optimizing the cost of core materials has become a major goal of our research and development.

1.2. Optimize the production ingredients and processes of core materials

Optimizing the ingredient process involves issues such as product quality and production efficiency. We have developed a relatively optimized production ingredient and process through repeated experiments, which is easy to master, stable, and consistent.

1.3. Inherit the original production process of metal composite panels

According to research, there are currently nearly 200 domestic metal composite panel production enterprises and over 600 continuous thermal composite production lines. The high flame retardant steel plastic composite board we have researched and implemented basically inherits the requirements of the original production process, and only requires moderate adjustments to the extrusion process equipment, thermal composite process, tension and other parameters.

1.4. The product meets the requirements of low-carbon environmental protection
The developed high flame retardant core material samples are halogen-free, low smoke, extremely difficult to burn or non combustible, and can withstand combustion or high-temperature carbonization

There are basically no harmful gases or black smoke produced, which meets the environmental protection requirements of building materials.

2. Selection of technical principles and process routes

Steel plastic composite board is a three-layer composite board with plastic as the core layer and pre rolled galvanized steel plate/or stainless steel plate attached externally. The production process generally adopts hot stamping technology. The bonding between the metal panel and the core layer is achieved through multi-layer co extruded polymer hot melt adhesive polymer film, which softens and is compatible with the plastic core layer under certain temperature, pressure, and time conditions. The polymer hot melt adhesive has polarity and is bonded to the steel plastic plate, and then cooled and shaped to obtain a steel plastic composite plate. This process can maintain continuous production, high degree of automation, good product quality stability, simple process operation, and stable product quality.

3、 Trial production, development, and performance evaluation of fire-resistant steel plastic composite panels

Selecting halogen-free high flame retardant special materials developed and industrialized by Hunan KEOCT Materials Co., Ltd. as the core material for fireproof steel plastic composite panels, following the same process as ordinary steel plastic composite panels: extruding flame-retardant special materials into flame-retardant panels; Loading and unloading of steel coils, tension control, preheating; Polymer film feeding, preheating → hot bonding → hot pressing rolling → cold pressing shaping → cooling → protective film pasting → driving → cutting → finished product and other continuous hot pressing composite production processes can produce fireproof steel plastic composite panels of different colors, varieties and thickness specifications.

1.1 Main raw materials
Halogen free flame retardant special material: KT-A1621/2621, developed and produced by Hunan KEOCT Materials Co., Ltd;
Fluorocarbon roller coated patterned steel plate: galvanized alloy steel plate/stainless steel plate with a thickness of 0.30-0.40 mm, industrial product;
Fluorocarbon roller coated aluminum plate: thickness 0.50mm, industrial product;

Polymer adhesive film: thickness 0.05~0.10 mm, industrial product.

1.2 Main production equipment

Online extrusion continuous hot press composite production line: 180/280KW single screw extruder;Or 75/3600 twin-screw extruder, 132-160 kW variable frequency main motor

1.3 Process Flow

Flame retardant material → Extruded sheet → hot pressing and bonding → cold pressing and forming → cooling → protective film → driving → cutting → finished product → performance testing

Upper and lower steel coil → feeding, preheating → hot pressing and bonding → cold pressing and forming → cooling → protective film → driving → cutting → finished product → performance testing

Polymer film → Feed, preheat → hot pressing and bonding → cold pressing and forming → cooling → protective film → driving → cutting → finished product → performance testing

1.4 Selection of test application sample parameters

We screened three kinds of metal composite plate materials for experimental research, and the specific specifications are shown in Table 1.

1.5 Test results and evaluation analysis

1.5.1 Comparison of technical performance index requirements and test results of different flame retardant and fire retardant types of core materials
The environment-friendly halogen-free flame retardant functional materials developed and produced by our company have been jointly tested by Hunan Plastic Product Quality Supervision and authorized Station and China aluminum-plastic composite building Materials Industry flame retardant Technology R&D Center, and their physical and mechanical properties are tested in Table 2.

On the composite plate production line, the fire-resistant aluminum-plastic composite plate and fire-resistant steel-plastic composite plate for building curtain wall are continuously produced by hot-pressing.

Composite board, by the national fire protection building materials supervision and inspection Center for products in accordance with GB 8624-2012 "Building materials and
Product combustion performance classification standard for testing, in line with B-s1,d0,t0 levels. The combustion test results are shown in Table 3.

As can be seen from Table 3, under the condition that the total thickness is 4 mm, the thickness of alloy steel plate is 0.30/0.30mm, and the thickness of aluminum alloy plate is 0.50/0.50mm, the fireproof steel plastic board made of halogen-free flame retardant core material, whether it is aluminum plastic composite board or steel plastic composite board, has good combustion performance indicators. According to GB8624-2012< Combustion Performance Classification of Building Materials and Products > standard, its combustion performance grades have reached the higher fire rating requirements of B1 (B-s1,d0, t0). National Fire Prevention Building Materials Quality Inspection Center report number: 201412058,201410696.

Model/variety	Test item	Unit	Test method	Index requirement	Detection result	evaluate
KT-A1621	Melt index	g/10min	KT-A 2621	Melt index	g/10min	GB/T3682	0.8～1.5	1.20	Up to standard

Test parameter	Technical indicators	Fireproof steel plastic panel (flame retardant core material)	Fireproof aluminum-plastic panel (flame retardant core material)
Combustion Growth Rate Index (FIGRA) /W·s-1	≤120	≤0	≤0
Total heat release in 600 s （THR 600 s）/MJ	≤7.5	≤1.2	≤0.5
Lateral flame spread length（LFS）/m	＜sample edge	＜sample edge	＞sample edge
Flue Gas Production Rate Index（SMOGRA）/m²·s-²（4）	≤30	0	0
Total smoke production in 600 s （TSP 600 s）/m²	≤50	≤18	≤22
Burning droplets/particles	no	no	no
Smoke toxicity	ZA1	ZA1	ZA1
Combustion performance class	B1（B-s1,d0，t0）	B1（B-s1,d0，t0）	B1（B-s1,d0，t0）

1.5.2.2 Analysis and comparison of physical and mechanical properties of steel-plastic composite panels of different core material types

The developed 0.30*0.30*4.0 fireproof steel-plastic composite board was produced by the National Building Materials Quality Supervision and Inspection Center
Products in accordance with GB 17748 "building curtain wall aluminum-plastic composite panel" standard test, the physical and mechanical properties of the index, symbol
Meets GB/T17748 standard requirements. National Building Materials Quality Supervision Center test report, No. : WT2014B02N01229, 20131I02689

Serial number	Inspection item	Standard index	Fireproof steel plastic board test value	Test value of ordinary steel-plastic plate
1	Bending strength	≥100MPa	175 MPa	≥197 MPa
2	Flexural elastic modulus	≥2.0×104MPa	5.7×104MPa	6.8×104MPa
3	Penetration resistance	≥7.0kN	14.8 kN	16.1KN
4	Shear strength	≥22.0MPa	46.7 MPa	60.6 MPa
5	Drum stripping strength	Average value:130N.mm/mm Minimum value:120N.mm/mm	Average value:221N.mm/mm Minimum value:198N.mm/mm	Average value:≥287N.mm/mm Minimum value:≥262N.mm/mm
6	Heat resistance water	No abnormalities	No abnormalities	No abnormalities
7	Thermal deformation temperature	≥95℃	112℃	97℃
Conclusion	The test results of the items inspected by the sample meet the technical requirements of GB/T17748.

It can be seen from Table 4 that according to GB/T 17748 standard, the total thickness is 4 mm and the thickness of the steel plate is 0.30/0.30mm
The physical and mechanical properties of the fire-resistant steel-plastic composite board made of halogen-free flame retardant core material are all the same under the conditions
Better than ordinary steel-plastic composite board. In particular, the thermal deformation temperature of 112 ° C is higher than the latest standard for submission and approval. roller
The measured data of peel strength were all exceeded, with the average value ≥221N.mm/mm and the minimum value ≥198N.mm/mm

Standard technical requirements.

2, the impact of manufacturing process and extrusion composite production process parameters on performance
Having halogen-free flame retardant material technology does not mean that you can produce qualified B-s1,d0, t0 grade fire retardant steel composite board. According to the requirements of the formula characteristics, due to the large amount of halogen-free flame retardants in the core material, up to more than 70%, if used improperly, it will reduce the physical and chemical properties of the plate, especially the drum peel strength and thermal deformation temperature, and affect the processing flow, so that the composite effect will be affected in the continuous hot pressing composite production, the scrap rate will increase, and the continuous production cannot be achieved. This is one of the reasons why many companies also have halogen-free flame retardant technology but cannot form large-scale production.

Extrusion production of steel-plastic composite sheet, in addition to strict control of raw materials of low molecular matter such as water content <0.3%, should also control the extrusion process temperature, extrusion speed and feeding speed matching, melt pressure, vacuum degree and other parameters, to ensure that the surface of the extruded sheet flat without depression, dense no porosity, uniform plasticization. When composite, the composite process parameters such as: discharge tension, hot press roller temperature, drive line speed, roller gap, etc., should be properly adjusted to ensure that the physical and mechanical properties of the continuous hot press composite production of fireproof steel plate, especially the drum peel strength and thermal deformation temperature, is not lower than the GB/T17748-2015 latest approval draft standard requirements.

4. Conclusion

(1) The new fire-resistant steel-plastic composite board developed by this project is made of halogen-free high-flame retardant core layer material. The fire-resistant steel-plastic composite board prepared by this project has been tested by authorities, and the combustion performance and physical and mechanical properties meet or exceed the index requirements of GB8624-2012 and GB/T17748-2015 "Aluminum-plastic Composite Board for Building Curtain Wall" standard revision (draft for approval). The performance has reached the advanced level of the latest similar foreign products;

(2) The developed new halogen-free high flame retardant core layer material for fire-resistant steel-plastic composite panels has been built into an industrial production line and put into mass production, breaking the pattern that only a few brand companies such as Germany and Japan can produce this material, and the performance has reached the advanced level of similar foreign products;

(3) After the application and promotion of the product of this project, it can meet people's requirements for fire safety and low-carbon environmental protection, no harmful smoke and toxic release in case of fire, conducive to personnel evacuation and fire prevention work, improve public safety, reduce carbon dioxide emissions, and save a lot of non-ferrous metal materials, petroleum resources and other plastic resin materials.