Introduction of commonly used adhesive resins

Adhesive resins are often used in multi-layer coextrusion compounding technology and coating compounding technologies, such as TIE by DuPont, Mitsubishi Corporation of Japan, ADMER by Mitsui Corporation of Japan, SK Corporation of Japan, SK Corporation of Korea, and Atofina Corporation of Japan. The products, as well as related products of Nanjing Aoguang and Nanjing Liuhe Company.

Binder resins are generally a class of graft modified polymers. The functional branch is formed by grafting the comonomer on the main chain of the polymer, so that the functional branch exposed outside the main chain reacts rapidly and efficiently with the material to be adhered. The wetting, diffusion, chemical bonding, and physical entanglement of adhesive materials are the main factors that determine the bond strength.

Commonly used adhesive polymers are anhydride modified ethylene-vinyl acetate, polyethylene, polypropylene polymers and some acid copolymers. According to the type of polymer carrier used for bonding PE, PP, Sarin, EVA, PA, and EVOH, PVC, paper, etc., these adhesive resins can be used for ordinary extrusion and co-extrusion equipment for processing.

The function of the binding resin is to bind together resins or substrates that are generally not bondable to one another. The effect of its adhesion is usually characterized by its peel strength.

1. Anhydride modified ethylene-vinyl acetate copolymer (abbreviated as EVA modified adhesive resin)

Like EVA, its modified adhesive resin has a density and melting finger similar to that of EVA resin, which can bond a variety of materials. For example: PE, EVA, PA6, Sarin.

The EVA modified binder resin must ensure sufficient time for the anhydride to activate during co-extrusion to ensure sufficient adhesion. Therefore, the temperature setting is very important. In order to ensure adhesive strength, the adhesive resin melt should be maintained at a melt temperature of 210 degrees Celsius or more for several minutes before the adhesive resin contacts other adhered materials, thereby ensuring its adhesion during co-extrusion processing. performance.

In order to prevent degradation of EVA due to high processing temperatures, the processing temperature should be limited to 238 degrees.

If the bonding performance is good, the processing temperature can be reduced to about 230 degrees. The longer the binder resin is above 210 degrees, the more fully the anhydride is activated. However, an excessively long temperature or dead angle in the extruder may cause the resin to age due to excessive residence time.

Specific temperature settings must also be adjusted based on factors such as the design of the screw, back pressure limitations of the extruder, pressure limitations, co-extrusion and rheological properties of other materials, and thermal stability effects of other materials. In addition, the residence time of the binder resin in the extruder also affects the quality of the film, and it should be made as smooth as possible in the extruder.

Since the acid anhydride-modified EVA binder resin has a low softening point, the temperature of the feed section of the extruder should be kept as low as possible during processing, and then the temperature is rapidly raised to the melting point in the compression section.

Resin bridging problems can often be avoided by cooling the barrel throat and the screw feed section with water. To select a suitable screw according to the need for the amount of extrusion, a standard polyolefin screw can be used but deep grooves are to be avoided influencing the shear melting of the binder resin. At the same time, it should avoid using an excessively large screw to extrude adhesive resin at low speed.

2. Anhydride-modified linear low-density polyethylene polymer (referred to as LLDPE adhesive resin)

Has similar and linear low density polyethylene LLDPE density and melt index. Can be bonded to a variety of materials, such as: ethylene vinyl alcohol copolymer (EVOH), PA6, PE, ionomers (salin) and ethylene copolymers. Has similar physical properties as LLDPE resin. Can be used for blown film, cast film / sheet co-extrusion process. Coextruded films produced with LLDPE binder resin to produce polyethylene barrier structures have better heat resistance than those produced with EVA binder resins.

It can also be used in co-extrusion coating processes where the rheology of each grade of resin is different, and therefore has its own specific application.

LLDPE adhesive resin has good adhesion to EVOH and excellent adhesion to PA.

As with the EVA above, the setting of the processing temperature is critical.

It is maintained at a melting temperature above 200 degrees for a few minutes to activate the anhydride groups.

When coextruding a resin-based heat-sensitive resin material such as EVA or EVOH, the processing temperature of the acid anhydride-modified LLDPE-bonded resin must not exceed 235 degrees in order to prevent excessive temperatures of EVA and EVOH.

If the adhesion is good enough, the bonding resin processing temperature can be reduced to 210-220 degrees.

When co-extruded with nylon PA and other thermally stable resins, the processing temperature can be higher, up to a maximum of 250 degrees. And can be reduced appropriately. Above 260 degrees, there will be crystal problems.

When the co-extrusion process is used: controlling the material and process parameters and matching the melt viscosities of different materials is the most critical process technology.

3, acid anhydride modified polypropylene polymer (referred to as PP adhesive resin)

Has a similar density and melt index to polypropylene PP. Can bind a variety of materials, such as: PP, ethylene-vinyl alcohol copolymer (EVOH), PA6.

Has similar physical properties as PP resin. Can be used for blown film, cast film / sheet co-extrusion process.

The temperature setting is very important. In order to ensure adhesive strength, the adhesive resin melt should be maintained at a melt temperature of 210 degrees Celsius or more for several minutes before the adhesive resin contacts other adhered materials, thereby ensuring its adhesion during co-extrusion processing. performance.

When coextruding a resin-based heat-sensitive resin material such as EVA or EVOH, in order to prevent the temperature of EVA and EVOH from being too high, the processing temperature of the acid anhydride-modified PP adhesive resin must not exceed 235 degrees.

If the adhesion is good enough, the bonding resin processing temperature can be reduced to 210-220 degrees.

When co-extruded with nylon PA and other thermally stable resins, the processing temperature can be higher, up to a maximum of 250 degrees.

4, anhydride modified high-density polyethylene polymer (HDPE adhesive resin for short)

With strong toughness and high temperature resistance, it is widely used in coextrusion casting, blown film, sheet boiling resistance structure, PE and PA, EVOH adhesion, aluminum-plastic bonding structure and so on.

Temperature setting: The processing temperature of anhydride modified HDEP adhesive resin must not exceed 235 degrees.

If the adhesion is good enough, the bonding resin processing temperature can be reduced to 210-220 degrees.

When co-extruded with nylon PA and other thermally stable resins, the processing temperature can be higher, up to a maximum of 250 degrees.

5, ethylene and methacrylate copolymer (mainly for coating)