PA6 聚酰胺6或尼龙6
典型应用范围:
由于有很好的机械强度和刚度被广泛用于结构部件。由于有很好的耐磨损特性，还用于制造轴承。
注塑模工艺条件:
干燥处理：由于PA6很容易吸收水分，因此加工前的干燥特别要注意。如果材料是用防水材料包装
供应的，则容器应保持密闭。如果湿度大于0.2%，建议在80C以上的热空气中干燥16小时。如果
材料已经在空气中暴露超过8小时，建议进行105C，8小时以上的真空烘干。
熔化温度：230~280C，对于增强品种为250~280C。
模具温度：80~90C。模具温度很显著地影响结晶度，而结晶度又影响着塑件的机械特性。
对于结构部件来说结晶度很重要，因此建议模具温度为80~90C。对于薄壁的，流程较长的塑件
也建议施用较高的模具温度。增大模具温度可以提高塑件的强度和刚度，但却降低了韧性。
如果壁厚大于3mm，建议使用20~40C的低温模具。对于玻璃增强材料模具温度应大于80C。
注射压力：一般在750~1250bar之间（取决于材料和产品设计）。
注射速度：高速（对增强型材料要稍微降低）。
流道和浇口:
由于PA6的凝固时间很短，因此浇口的位置非常重要。浇口孔径不要小于0.5*t
（这里t为塑件厚度）。如果使用热流道，浇口尺寸应比使用常规流道小一些，
因为热流道能够帮助阻止材料过早凝固。如果用潜入式浇口，浇口的最小直径应当是0.75mm。
化学和物理特性:
PA6的化学物理特性和PA66很相似，然而，它的熔点较低，而且工艺温度范围很宽。
它的抗冲击性和抗溶解性比PA66要好,但吸湿性也更强。因为塑件的许多品质特性
都要受到吸湿性的影响，因此使用PA6设计产品时要充分考虑到这一点。为了提高
PA6的机械特性，经常加入各种各样的改性剂。玻璃就是最常见的添加剂，有时为了
提高抗冲击性还加入合成橡胶，如EPDM和SBR等。
对于没有添加剂的产品，PA6的收缩率在1%到1.5%之间。加入玻璃纤维添加剂可以使
收缩率降低到0.3%（但和流程相垂直的方向还要稍高一些）。成型组装的收缩率主要
受材料结晶度和吸湿性影响。实际的收缩率还和塑件设计、壁厚及其它工艺参数成函数关系。
PA 6
Generic Class
PA 6 (Polyamide 6, or Nylon 6, or Polycaprolactam)
Applications
Used in many structural applications because of its good mechanical strength and rigidity. It is used in bearings because of its good wear resistance.
Injection Molding processing conditions
Drying Since PA 6 absorbs moisture readily, care should be taken to ensure its dryness prior to molding. If the material is supplied in watertight packaging, the containers should be kept closed. If the moisture content is >0.2%, drying in a hot air oven at 80 C (176 F) for 16 hours is recommended. If the material has been exposed to air for more than 8 hours, vacuum drying at 105 C (221 F) for more than 8 hours is recommended.
Melt Temperature 230 - 280 C (446 - 536 F); 250 - 300 C (482 - 572 F) for reinforced grades
Mold Temperature 80 - 90 C (176 - 194 F). Mold temperature significantly influences the crystallinity level which in turn affects the mechanical properties. For structural parts, a high degree of crystallization is required and mold temperatures of 80 - 90 C (176 - 194 F) are recommended. High mold temperatures are also recommended for thin-wall parts with long flow lengths. Increasing the mold temperature increases the strength and hardness, but the toughness is decreased. When the wall thickness is greater than 3 mm, a cold mold is recommended (20 - 40 C / 68 - 104 F), which leads to a higher and more uniform degree of crystallinity. Glass reinforced resins are always processed at mold temperatures greater than 80 C (176 F).
Resin Injection Pressure Generally between 750 - 1,250 bar (~11,000 - 18,000 psi) (depends on material and product design)
Injection Speed High (slightly lower for reinforced grades)
Runners and Gates
The gate location is important because of very fast freeze-off times. Any type of gate may be used; the aperture should not be less than half the thickness of the part. When hot runners are used, the size of the gates can be smaller than when cold runners are used, because premature freeze-off is prevented. When using submarine gates, the minimum diameter of the gate should be 0.75 mm.
Chemical and Physical Properties
The molecular structure of polyamides consist of amide (CONH) groups joined by linear aliphatic sections (based on methylene groups). The toughness, rigidity, crystallinity, and thermal resistance of polyamide resins are due to the strong interchain attraction caused by the polarity of the amide groups. The CONH groups also cause a lot of moisture absorption.
Nylon 6 is produced by polymerization of caprolactam. The chemical and physical properties are similar to that of PA 66. However, its melting point is lower than PA 66 and it has a wider processing temperature range. Its impact strength and solvent resistance are better than PA 66, but its moisture absorption is higher. Many properties are affected by moisture absorption, which must be taken into account when designing with this resin. Various modifiers are added to improve mechanical properties; glass is one of the most commonly used fillers. Addition of elastomers such as EPDM or SBR improves impact resistance.
For unfilled grades, shrinkage is of the order of .01 - .015 mm/mm (1 - 1.5%). Addition of glass fibers reduce the shrinkage to as low as 0.3% in the flow direction (but could be as high as 1% in the cross-flow direction). The post-molding shrinkage is affected mainly by the crystallinity level and moisture absorption. The actual shrinkage is a function of part design, wall thickness, and processing conditions.
Major Manufacturers
BASF (Ultramid  , DuPont (Zytel), DSM (Akulon)
PA66 聚酰胺66或尼龙66
典型应用范围:
同PA6相比，PA66更广泛应用于汽车工业、仪器壳体以及其它需要有抗冲击性和高强度要求的产品。
注塑模工艺条件:
干燥处理：如果加工前材料是密封的，那么就没有必要干燥。然而，如果储存容器被打开，那么建议在85C的热空气中干燥处理。如果湿度大于0.2%，还需要进行105C，12小时的真空干燥。
熔化温度：260~290C。对玻璃添加剂的产品为275~280C。熔化温度应避免高于300C。
模具温度：建议80C。模具温度将影响结晶度，而结晶度将影响产品的物理特性。对于
薄壁塑件，如果使用低于40C的模具温度，则塑件的结晶度将随着时间而变化，为了保持
塑件的几何稳定性，需要进行退火处理。
注射压力：通常在750~1250bar，取决于材料和产品设计。
注射速度：高速（对于增强型材料应稍低一些）。
流道和浇口:
由于PA66的凝固时间很短，因此浇口的位置非常重要。浇口孔径不要小于0.5*t
（这里t为塑件厚度）。如果使用热流道，浇口尺寸应比使用常规流道小一些，
因为热流道能够帮助阻止材料过早凝固。如果用潜入式浇口，浇口的最小直径
应当是0.75mm。
化学和物理特性:
PA66在聚酰胺材料中有较高的熔点。它是一种半晶体-晶体材料。PA66在较高温度也能保持较强的强度和刚度。PA66在成型后仍然具有吸湿性，其程度主要取决于材料的组成、壁厚以及环境条件。在产品设计时，一定要考虑吸湿性对几何稳定性的影响。
为了提高PA66的机械特性，经常加入各种各样的改性剂。玻璃就是最常见的添加剂，有时为了提高抗冲击性还加入合成橡胶，如EPDM和SBR等。
PA66的粘性较低，因此流动性很好（但不如PA6）。这个性质可以用来加工很薄的元件。
它的粘度对温度变化很敏感。PA66的收缩率在1%~2%之间，加入玻璃纤维添加剂可以将
收缩率降低到0.2%~1% 。收缩率在流程方向和与流程方向相垂直方向上的相异是较大的。
PA66对许多溶剂具有抗溶性，但对酸和其它一些氯化剂的抵抗力较弱。
PA 66
Generic Class
PA 66 (Polyamide 66, or Nylon 66, or poly (hexamethylene adipamide))
Applications
Competes with PA 6 for most applications. PA 66 is heavily used in the automotive industry, appliance housings, and generally where impact resistance and strength are required.
Injection Molding Processing conditions
Drying Drying is not required if the material is sealed prior to molding; however, if the containers are left open, drying in a hot air oven at 85 C (185 F) is recommended. If the moisture content is > 0.2%, vacuum drying at 105 C (220 F) for 12 hours is recommended.
Melt Temperature 260 - 290 C (500 - 554 F); 275 - 280 C (527 - 536 F) for glass filled grades; melt temperatures above 300 C (572 F) should be avoided
Mold Temperature 80 C (176 F) suggested. Mold temperature affects crystallinity level which in turn affects physical properties. In the case of thin walled parts, crystallinity changes with time if mold temperatures of less than 40 C (104 F) are used. In such cases, annealing may be needed to retain dimensional stability.
Resin Injection Pressure Generally between 750 - 1,250 bar (~11,000 - 18,000 psi), depends on material and product design
Injection Speed High (slightly lower for reinforced grades)
Runners and Gates
The gate location is important because of very fast freeze-off times. Any type of gate may be used; the aperture should not be less than half the thickness of the part. When hot runners are used, the size of the gates can be smaller than when cold runners are used, because premature freeze-off is prevented. When using submarine gates, the minimum diameter of the gate should be 0.75 mm.
Chemical and physical properties
PA 66 homopolymer is produced by the polymerization of hexamethylene diamine and adipic acid (a dibasic acid). Among commercially available polyamides, PA 66 has one of the highest melting points. It is a semicrystalline-crystalline material. The resins have strength and stiffness which is retained at elevated temperatures. It does absorb moisture after molding, but the retention is not as much as in the case of PA 6. Moisture absorption depends on the composition of the material, wall thickness, and environmental conditions. Dimensional stability and properties are all affected by the amount of moisture absorption which must be taken into account for product design.
Various modifiers are added to improve mechanical properties; glass is one of the most commonly used filler. Addition of elastomers such as EPDM or SBR improves impact resistance.
The viscosity is low and therefore, it flows easily (but not as easily as PA 6). This allows molding of thin components. The viscosity is very sensitive to temperature. Shrinkage is of the order of 0.01 - 0.02 mm/mm (1 - 2%). Addition of reinforcing glass fibers reduces the shrinkage to 0.2 - 1%. Differential shrinkage in the flow and cross-flow directions is quite high. Mineral fillers yield more isotropic moldings. PA 66 is resistant to most solvents but not to strong acids or oxidizing agents.
Major Manufacturers
BASF (Ultramid A), DuPont (Minlon - mineral reinforced grades; Zytel), Monsanto (Vydyne), DSM (Akulon).
PBT 聚对苯二甲酸丁二醇酯
典型应用范围:
家用器具（食品加工刀片、真空吸尘器元件、电风扇、头发干燥机壳体、咖啡器皿等），电器元件（开关、电机壳、保险丝盒、计算机键盘按键等），汽车工业（散热器格窗、车身嵌板、车轮盖、门窗部件等）。
注塑模工艺条件:
干燥处理：这种材料在高温下很容易水解，因此加工前的干燥处理是很重要的。建议在空气中的干燥条件为120C,6~8小时，或者150C，2~4小时。湿度必须小于0.03%。如果用吸湿干燥器干燥，建议条件为150C，2.5小时?
熔化温度：225~275C，建议温度：250C 。
模具温度：对于未增强型的材料为40~60C。要很好地设计模具的冷却腔道以减小塑件的弯曲。热量的散失一定要快而均匀。建议模具冷却腔道的直径为12mm。
注射压力：中等（最大到1500bar）。
注射速度：应使用尽可能快的注射速度（因为PBT的凝固很快）。
流道和浇口:
建议使用圆形流道以增加压力的传递（经验公式：流道直径=塑件厚度+1.5mm）。可以使用各种型式的浇口。也可以使用热流道，但要注意防止材料的渗漏和降解。浇口直径应该在0.8~1.0*t之间，这里 t是塑件厚度。如果是潜入式浇口，建议最小直径为0.75mm。
化学和物理特性:
PBT是最坚韧的工程热塑材料之一，它是半结晶材料，有非常好的化学稳定性、机械强度、电绝缘特性和热稳定性。这些材料在很广的环境条件下都有很好的稳定性。 PBT吸湿特性很弱。
非增强型PBT的张力强度为50MPa，玻璃添加剂型的PBT张力强度为170MPa。玻璃添加剂过多将导致材料变脆。PBT的；结晶很迅速，这将导致因冷却不均匀而造成弯曲变形。对于有玻璃添加剂类型的材料，流程方向的收缩率可以减小，但与流程垂直方向的收缩率基本上和普通材料没有区别。一般材料收缩率在1.5%~2.8%之间。含30%玻璃添加剂的材料收缩0.3%~1.6%之间。熔点（225%C）和高温变形温度都比PET材料要低。维卡软化温度大约为170C。玻璃化转换温度（glass trasitio temperature）在22C到43C之间。
由于PBT的结晶速度很高，因此它的粘性很低，塑件加工的周期时间一般也较低。
PBT
Generic Class
PBT (Polybutylene Terephthalates)
Typical Applications
Household appliances (food processor blades, vacuum cleaner parts, fans, hair dryer housings, coffee makers, etc.), electronics (switches, motor housings, fuse cases, key caps for computer keyboards, connectors, fiber optic buffer tubing, etc.), automotive (grilles, body panels, wheel covers, and components for doors and windows, etc.)
Injection Molding Processing Conditions
Drying This material is sensitive to hydrolysis at high temperatures. It is therefore important to dry the material prior to molding. Suggested drying conditions (in air) are 120 C (248 F) for 6 - 8 hours (or 150 C (300 F) for 2 - 4 hours). Moisture levels must be below 0.03%. When using a desiccant dryer, drying at 120 C (248 F) for 2.5 hours is recommended.
Melt Temperature 220 - 280 C (428 - 536 F); aim: 250 C (482 F)
Mold Temperature 40 - 60 C (104 - 140 F) for unreinforced grades. For other grades, a wide range of temperatures can be used, depending on the grade (15 - 80 C / 59 - 176 F). Cooling channels should be properly designed to minimize part warpage. The heat removal must be fast and uniform. Cooling channels of 12 mm diameter are recommended.
Resin Injection Pressure Moderate (up to maximum of 1500 bar / 21750 psi).
Injection Speed Fastest possible speeds should be used (due to fast solidification of PBTs)
Runners and Gates
Full round runners are recommended to impart maximum pressure transmission (rule of thumb: runner diameter = part thickness + 1.5 mm). A wide variety of gates may be used. Hot runners may also be used, taking care to avoid drool and material degradation. Gate diameters or depths should preferably be between 0.8 - 1.0 times the part thickness. When using submarine gates, the minimum recommended diameter is 0.75 mm.
Chemical and Physical Properties
PBT is one of the toughest engineering thermoplastics. It is a semicrystalline resin and has excellent chemical resistance, mechanical strength, electrical properties (high dielectric strength and insulation resistance), and heat resistance, all of which are stable over a broad range of environmental conditions. It has very low moisture absorption.
PBT, which is a polyester, is produced by the polycondensation reaction of dimethyl terephthalate an butanediol.
Tensile strength ranges from 50 MPa (7,250 psi) for unfilled grades to 170 MPa (24,650 psi) for glass reinforced grades. High levels of glass fillers make the material more brittle. Crystallization is rapid and this could cause warpage due to non-uniform cooling. In the case of glass filled grades, shrinkage is reduced in the flow direction, but in the cross-flow direction it may be equal to that of the base resin. Shrinkage is of the order of 0.015 - 0.028 mm/mm (1.5 -2.8%). A 30% glass-filled resin has a shrinkage range of 0.3 - 1.6%. The melting point (approximately 225 C / 437 F) and heat distortion temperatures are lower than that of PET. The Vicat softening point is approximately 170 C (338 F). The glass transition temperature ranges from 22 - 43 C (71 - 109 F).
The melt viscosity is fairly low and due to fast crystallization rates, cycle times are typically low.
Major Manufacturers
BASF (Ultradur), Ticona (Celanex), GE Plastics (Lomod, Valox), Bayer (Pocan), Huls (Vestoduv), Mitsubishi Engineering Plastics (Novadur), Teijin Chemicals. |
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发表于 2002-12-8 23:29:17
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