Seven System Types of Hot Melt Adhesive

System Type 1: Ethylene and its copolymers

1. EVA (ethylene-vinyl acetate copolymer)

EVA resin is an odorless, non-toxic, white or light yellow powdery or granular low melting point polymer. When the MI is large, the molecular weight is small, the synthesized hot melt adhesive has low viscosity, and the fluidity is good.

Advantages: good adhesion, softness and heating fluidity.

Disadvantages: low strength, not heat resistant, not resistant to fatty oil, can not be used as structural adhesive.

2. EEA (ethylene-ethyl acrylate copolymer)

The EEA resin which is a hot melt adhesive base has an ethyl acrylate content of about 23%. Its structure is similar to that of EVA, but its use temperature is wide, thermal stability is good, and polarity is low. It is often used in high temperature coating, where viscosity and strength are required, and it has good adhesion to both polar and non-polar substrates.

3. EAA (ethylene-acrylic acid copolymer)

EAA contains a highly polar carboxyl group which gives it good adhesion to both metals and non-metals. The properties of the EAA resin are also related to the monomer content of the acrylic acid. When the acrylic acid content is increased, the transparency of the film, the low-temperature heat-sealing property, and the low-temperature heat-adhesive property are improved, and the adhesion to the metal and the tensile strength of the hot-melt adhesive are improved.

4, EVAL (ethylene-vinyl acetate-vinyl alcohol terpolymer)

EVAL makes the saponified product of EVA a white or light yellow powder or granule. The EVAL molecule contains a hydroxyl group, which improves the adhesion to the polar substrate and improves the rigidity, processability and colorability of the resin.

System Type 2: Polyolefin (PO)

1, PE (polyethylene)

PE is a non-toxic, low-temperature resistant, highly crystalline, chemically resistant, non-stick material. Low MI, high molecular weight, high heat-resistant seal strength, good flexibility and good thermal adhesion. The MI used for hot melt adhesives is 2-20 g/10 min. Since polyethylene is a non-polar material, a low polarity compounding agent is required.

2, PP (polypropylene)

Depending on the position of the methyl space, there may be isotactic, syndiotactic and random polypropylene. The production of hot melt adhesives usually uses atactic polypropylene (APP) as a matrix. Such hot melt adhesives have a slow curing speed and a low heat resistance, so low molecular weight polyethylene or crystalline polypropylene is often added.

System Type 3: APAO

APAO (ethylene-propylene-1-butene polymer) is an amorphous polyalphaolefin. Compared with EVA, it has a wider temperate zone, excellent substrate adhesion, firm adhesion, and can be used for structural adhesives with high strength requirements. Due to the copolymer, the properties cover a wide range (eg viscosity, softening point and hardness). And it is compatible with many raw materials.

System Type 4: Polyester (PES)

Polyester is divided into two types: unsaturated polyester and thermoplastic polyester. As a hot melt adhesive, a thermoplastic polyester, that is, a linear saturated polyester is used as a base material, which is obtained by polycondensation of a dibasic acid and a glycol or an alkyd. The thermoplastic polyester has a higher melting point and glass transition temperature, and the obtained hot melt adhesive has good heat resistance. Polyester hot melt adhesives are used alone as copolymers and generally do not require the addition of other ingredients.

System Type 5: Polyurethane (PU)

Polyurethane is white irregular spherical or columnar particles, which are classified into two types: polyester type and polyether type. Commonly used polyester polyols are polymerized with diisocyanates. The most outstanding characteristics of polyurethane are excellent wear resistance, high hardness, high strength, good elasticity and low temperature resistance. Polyurethane reactive hot melt adhesives can be classified into hot melt curing type and hot melt heating reaction type.

System Type 6: Polyamide (PA)

Polyamide hot melt adhesive has strong bond strength, and the higher the molecular weight, the higher the strength and viscosity, but the melting point does not change much. Polyamide can be divided into two categories: one is Dimer acid based (high molecular weight, high melt viscosity, high softening point, high strength, but the processability of hot melt adhesive is reduced); first, nylon type (for the convenience of use, common formaldehyde treatment) Made of methylolated nylon).

Spiderbond polyamide hot melt adhesive is dimer acid based hot melt adhesive, the raw material is plant oleic acid, not only high performance, also environmentally friendly and no harm to the human body.

System Type 7: Styrene and its block copolymers

The characteristics of this type of copolymer are: vulcanized but vulcanized rubber, good creep, compatible with various blending materials, but its temperature resistance, UV light resistance and hydrocarbon-resistant solvent properties. Poor.

More Hot melt PA adhesives Choices

It includes: SBS (styrene-butadiene-styrene block copolymer), SIS (styrene-isoprene-styrene block copolymer)