當前位置:網站首頁 > 新聞資訊 > 行業資訊
行業資訊 | ALL PRODUCTS
  • 热熔胶和熱熔壓敏膠的定义与应用市场
  • 本站編輯:杭州大偉膠粘劑有限公司发布日期:2019-08-10 14:36 浏覽次數:
热熔胶和熱熔壓敏膠已廣泛應用于各種制造業40多年。幾乎所有行業,包括包裝、書籍裝訂、木工、DIY、衛生、建築、汽車、電子、制鞋、多層織物複合材料、産品組合、膠帶和標簽,使用大量的熱熔粘合劑和熱熔壓敏粘合劑。這些是什麽材料?
熱熔膠是一種固體含量100%的膠粘劑。它可以在熔融狀態下進行塗層以獲得適當的流動和濕潤(圖1-2)。熱熔膠需要冷卻到室溫才能獲得實際的粘合強度。熱熔膠在使用前後始終保持熱塑性。
压敏粘合剂是指在室温下具有表面粘合性并能无限长时间开放的粘合剂。因此,他们可以随时粘贴到另一个标签上。熱熔壓敏膠是一种在室温下只需施加少量压力就能形成有效粘合能力的热熔胶。它们通常用来制作标签和磁带。
熱熔膠可分爲兩類:非配方熱熔膠和配方熱熔膠。非配方熱熔膠是合成後的一種特殊膠粘劑,不需要用增粘劑或其它材料進行改性。典型的非處方熱熔膠是聚酯(PET)、聚酰胺(PA)、聚氨酯(PU)和聚烯烴(PO)。非配方熱熔膠在高溫下具有一定的粘結強度。粘合劑的“熱粘度”將暫時粘合在一起,冷卻和固化後將獲得適當的粘合強度。
配制的熱熔膠是由熱塑性彈性體、增粘劑等組分組成的固溶體。與非配方熱熔膠不同,這些熱塑性彈性體或單個組分在室溫或高溫下不能提供中等粘度。三種常用的熱塑性彈性體是苯乙烯嵌段共聚物(SBC)、乙烯-醋酸乙烯共聚物(EVA)和無定形聚烯烴(APO)。根據各應用市場的具體物理性能,可選擇各種類型的增粘劑(天然和合成材料)對這些熱塑性彈性體進行改性,以産生各種特殊的粘合性能。
市场上常用的热熔胶大多是基于EVA的配方。这些产品通常具有较短的开启时间(通常少于10秒)和较快的固化速度。它在室温下表现出很低的表面粘度。大多数熱熔壓敏膠是在SBC的基础上配制的。它们在室温下具有永久的表面附着性,在轻微的手指按压下能提供良好的附着性。许多APO基热熔胶从熔化状态冷却后具有很长的开孔时间。但是,这种热熔胶没有永久的开放时间,完全固化后,表面粘度会逐渐降低。这种独特的性能对粘合过程非常有用,因为粘合过程需要较长的涂层后打开时间和较低的粘合后表面粘度。当残余表面粘度较低时,可以避免在今后的储存或使用中对结合区边缘的污染。
完美的热熔粘合剂或热熔压敏粘合剂有什么特点?在实际的应用市场中没有完美的产品。所有胶粘剂必须根据实际需要设计或配制。那么,用户如何根据实际需要选择合适的热熔胶或熱熔壓敏膠呢?在为特定应用选择最理想的产品之前,必须清楚地了解和确定涂胶工艺和所需的胶水性能。
Hot-melt adhesive and hot-melt pressure-sensitive adhesive have been widely used in various manufacturing industries for more than 40 years. In almost all industries, including packaging, book binding, carpentry, DIY, sanitation, construction, automotive, electronics, footwear, multilayer fabric composites, product combinations, tapes and labels, a large number of hot-melt adhesives and hot-melt pressure-sensitive adhesives are used. What materials are these?
Hot melt adhesive is an adhesive with 100% solid content. It can be coated in a molten state for proper flow and wetting (figure 1-2). Hot melt adhesive needs to be cooled to room temperature to obtain the actual bonding strength. Hot melt adhesive before and after use always maintain thermoplastic.
 
Pressure-sensitive adhesive refers to the adhesive that has surface adhesion at room temperature and can open indefinitely for a long time. Therefore, they can be pasted to another label at any time. Hot-melt pressure-sensitive adhesive is a kind of hot-melt adhesive that can form effective bonding ability with only a small amount of pressure at room temperature. They are often used to make labels and tapes.
 
Hot melt adhesive can be divided into two categories: non - formula hot melt adhesive and formula hot melt adhesive. Non - formula hot melt adhesive is a special adhesive after synthesis. Typical over-the-counter hot melt adhesives are polyester (PET), polyamide (PA), polyurethane (PU), and polyolefin (PO). Non - formula hot melt adhesive at high temperature has a certain bond strength. The "thermal viscosity" of the adhesive will temporarily bond together, after cooling and curing will get the appropriate bonding strength.
 
The hot melt adhesive is a solid solution composed of thermoplastic elastomer and viscosifier. Unlike non-formulated hot melts, these thermoplastic elastomers or individual components do not provide moderate viscosity at room temperature or high temperature. The three commonly used thermoplastic elastomers are styrene block copolymer (SBC), ethylene - vinyl acetate copolymer (EVA) and amorphous polyolefin (APO). Depending on the specific physical properties of each application market, various types of viscosifiers (natural and synthetic materials) can be selected to modify these thermoplastic elastomers to produce a variety of special adhesive properties.
 
Hot melt adhesive commonly used in the market is mostly based on EVA formula. These products usually have a short opening time (usually less than 10 seconds) and a faster curing speed. It exhibits very low surface viscosity at room temperature. Most hot-melt pressure-sensitive adhesives are prepared on the basis of SBC. They have permanent surface adhesion at room temperature and provide good adhesion when pressed with a light finger. Many APO - based hot melt adhesives have long opening time after cooling from melting state. However, this hot melt adhesive does not have a permanent opening time, after completely curing, the surface viscosity will gradually reduce. This unique property is very useful for the adhesion process, which requires a longer time for the coating to open and a lower surface viscosity after adhesion. When the residual surface viscosity is low, it can avoid the contamination of the binding zone edge in future storage or use.
 
What are the characteristics of perfect hot melt adhesive or hot melt pressure sensitive adhesive? There is no perfect product in the real market. All adhesives must be designed or formulated according to actual needs. Then, how to choose the appropriate hot melt adhesive or hot melt pressure sensitive adhesive according to the actual needs? Before selecting the ideal product for a particular application, it is necessary to clearly understand and determine the gluing process and required glue properties.