PA6 聚酰胺6或尼龍6

典型應用范圍:
由于有很好的機械強度和剛度被廣泛用于結構部件。由于有很好的耐磨損特性，還用于制造軸承。

注塑模工藝條件:
干燥處理：由于PA6很容易吸收水分，因此加工前的干燥特別要注意。如果材料是用防水材料包裝
供應的，則容器應保持密閉。如果濕度大于0.2%，建議在80C以上的熱空氣中干燥16小時。如果
材料已經在空氣中暴露超過8小時，建議進行105C，8小時以上的真空烘干。
熔化溫度：230~280C，對于增強品種為250~280C。
模具溫度：80~90C。模具溫度很顯著地影響結晶度，而結晶度又影響著塑件的機械特性。
對于結構部件來說結晶度很重要，因此建議模具溫度為80~90C。對于薄壁的，流程較長的塑件
也建議施用較高的模具溫度。增大模具溫度可以提高塑件的強度和剛度，但卻降低了韌性。
如果壁厚大于3mm，建議使用20~40C的低溫模具。對于玻璃增強材料模具溫度應大于80C。
注射壓力：一般在750~1250bar之間（取決于材料和產品設計）。
注射速度：高速（對增強型材料要稍微降低）。
流道和澆口:
由于PA6的凝固時間很短，因此澆口的位置非常重要。澆口孔徑不要小于0.5*t
（這里t為塑件厚度）。如果使用熱流道，澆口尺寸應比使用常規流道小一些，
因為熱流道能夠幫助阻止材料過早凝固。如果用潛入式澆口，澆口的最小直徑應當是0.75mm。

化學和物理特性:
PA6的化學物理特性和PA66很相似，然而，它的熔點較低，而且工藝溫度范圍很寬。
它的抗沖擊性和抗溶解性比PA66要好,但吸濕性也更強。因為塑件的許多品質特性
都要受到吸濕性的影響，因此使用PA6設計產品時要充分考慮到這一點。為了提高
PA6的機械特性，經常加入各種各樣的改性劑。玻璃就是最常見的添加劑，有時為了
提高抗沖擊性還加入合成橡膠，如EPDM和SBR等。
對于沒有添加劑的產品，PA6的收縮率在1%到1.5%之間。加入玻璃纖維添加劑可以使
收縮率降低到0.3%（但和流程相垂直的方向還要稍高一些）。成型組裝的收縮率主要
受材料結晶度和吸濕性影響。實際的收縮率還和塑件設計、壁厚及其它工藝參數成函數關系。

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 B), DuPont (Zytel), DSM (Akulon)