阻止或延缓塑料燃烧的物质叫阻燃剂。从燃烧的3个要素和塑料的燃烧机理考虑,要使塑料阻然,必须从其燃烧产生的气相、固相和热量3个方面着手。塑料阻燃的主要途径列于表1中。
表1
阻燃途径 |
采取的具体措施 |
提高塑料的热稳定性 |
交联、工具与高分解温度塑料共混 |
提高塑料的导热性 |
添加无机填料或与导热性高的塑料共混 |
稀释可燃物和氧气 |
添加无机填料或能分解难燃气体的阻燃剂 |
添加自由基抑制剂 |
添加卤素或磷类阻燃剂 |
稀释或吸收燃烧过程中产生的热量 |
添加含结晶水的无机填料、低分子液体能分解吸收大量热量的物质 |
隔绝氧或炭化塑料保护 |
加入炭化剂 |
Physical Properties | Metric | English | Comments |
---|---|---|---|
Specific Gravity | 1.27 g/cc | 1.27 g/cc | ASTM D792 |
Maximum Moisture Content | 0.020 | 0.020 | Injection Molding |
Linear Mold Shrinkage, Flow | 0.0020 - 0.0040 cm/cm @Thickness 3.20 mm |
0.0020 - 0.0040 in/in @Thickness 0.126 in |
ASTM D955 |
Melt Flow | 12 g/10 min @Load 2.16 kg, Temperature 260 °C |
12 g/10 min @Load 4.76 lb, Temperature 500 °F |
ASTM D1238 |
Mechanical Properties | Metric | English | Comments |
Tensile Strength, Yield | 62.8 MPa @Thickness 3.20 mm |
9100 psi @Thickness 0.126 in |
50mm/min; ASTM D638 |
Flexural Yield Strength | 108 MPa @Thickness 3.20 mm |
15600 psi @Thickness 0.126 in |
10mm/min; ASTM D790 |
Flexural Modulus | 4.22 GPa @Thickness 3.20 mm |
612 ksi @Thickness 0.126 in |
10mm/min; ASTM D790 |
Izod Impact, Notched | >= 0.588 J/cm @Thickness 3.20 mm, Temperature 23.0 °C |
>= 1.10 ft-lb/in @Thickness 0.126 in, Temperature 73.4 °F |
ASTM D256 |
Thermal Properties | Metric | English | Comments |
Deflection Temperature at 1.8 MPa (264 psi) | 92.0 °C @Thickness 6.40 mm |
198 °F @Thickness 0.252 in |
Unannealed; ASTM D648 |
UL RTI, Electrical | 60.0 °C | 140 °F | |
UL RTI, Mechanical with Impact | 60.0 °C | 140 °F | |
UL RTI, Mechanical without Impact | 60.0 °C | 140 °F | |
Flammability, UL94 | V-0 @Thickness >=1.00 mm |
V-0 @Thickness >=0.0394 in |
|
V-0 @Thickness >=3.00 mm |
V-0 @Thickness >=0.118 in |
||
Processing Properties | Metric | English | Comments |
Rear Barrel Temperature | 230 - 250 °C | 446 - 482 °F | Injection Molding |
Middle Barrel Temperature | 245 - 265 °C | 473 - 509 °F | Injection Molding |
Front Barrel Temperature | 260 - 275 °C | 500 - 527 °F | Injection Molding |
Nozzle Temperature | 260 - 275 °C | 500 - 527 °F | Injection Molding |
Melt Temperature | 245 - 275 °C | 473 - 527 °F | Injection Molding |
Mold Temperature | 60.0 - 80.0 °C | 140 - 176 °F | Injection Molding |
Drying Temperature | 75.0 - 85.0 °C | 167 - 185 °F | Injection Molding |
Dry Time | 3.00 - 4.00 hour | 3.00 - 4.00 hour | Injection Molding |
Back Pressure | 0.0200 - 0.0600 MPa | 2.90 - 8.70 psi | Injection Molding |
Screw Speed | 40 - 70 rpm | 40 - 70 rpm | Injection Molding |
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通常阻燃剂可分为添加型和反应型两类。添加型阻燃剂能分散在塑料母体中,但与聚合物不发生键合反应;反应型阻燃剂则与塑料母体发生聚合反应,成为主体树脂的一种组分。塑料阻燃采用的具体方法概括起来主要有添加卤素类阻燃剂、磷类阻燃剂或无机阻燃剂等。塑料阻燃可单独使用上面任一类阻燃剂,也可复合使用两种或多种阻燃剂。事实上,一般都使用复合阻燃剂。无机阻燃剂价廉,燃烧时消烟,无滴落,无污染,毒性小,但添加量大,有的甚至要加到60% ~ 70%才有阻燃效果,从面对塑料性能影响较大,目前较少单独使用。卤素类、磷类阻燃剂,添加量少,阻燃性好,对塑料性能影响小,故多采用,且多与无机阻燃剂结合使用。