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  • 热熔胶和热熔压敏胶的定义与应用市场
  • 本站编辑:杭州亚虎官网登录有限公司发布日期:2019-08-10 14:36 浏览次数:
热熔胶和热熔压敏胶已广泛应用于各种制造业40多年。几乎所有行业,包括包装、书籍装订、木工、DIY、卫生、建筑、汽车、电子、制鞋、多层织物复合材料、产品组合、胶带和标签,使用大量的热熔粘合剂和热熔压敏粘合剂。这些是什么材料?
热熔胶是一种固体含量100%的胶粘剂。它可以在熔融状态下进行涂层以获得适当的流动和湿润(图1-2)。热熔胶需要冷却到室温才能获得实际的粘合强度。热熔胶在使用前后始终保持热塑性。
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。热熔压敏胶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。
热熔胶可分为两类:非配方热熔胶和配方热熔胶。非配方热熔胶是合成后的一种特殊胶粘剂,不需要用增粘剂或其它材料进行改性。典型的非处方热熔胶是聚酯(PET)、聚酰胺(PA)、聚氨酯(PU)和聚烯烃(PO)。非配方热熔胶在高温下具有一定的粘结强度。粘合剂的“热粘度”将暂时粘合在一起,冷却和固化后将获得适当的粘合强度。
配制的热熔胶是由热塑性弹性体、增粘剂等组分组成的固溶体。与非配方热熔胶不同,这些热塑性弹性体或单个组分在室温或高温下不能提供中等粘度。三种常用的热塑性弹性体是苯乙烯嵌段共聚物(SBC)、乙烯-醋酸乙烯共聚物(EVA)和无定形聚烯烃(APO)。根据各应用市场的具体物理性能,可选择各种类型的增粘剂(天然和合成材料)对这些热塑性弹性体进行改性,以产生各种特殊的粘合性能。
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。大多数热熔压敏胶是在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热熔压敏胶呢?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.
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