The hottest nylon film dry composite special adhes

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The scientific name of nylon is polyamide resin (PA), which is a polymer with repeated amide groups on macromolecules. It is formed by ring opening polymerization of lactam or condensation polymerization of diamine and dibasic acid. There are many kinds of nylon. At present, nylon film used for composite flexible packaging is mainly nylon 6, which is formed by ring opening polymerization of caprolactam; Nylon 66 is polycondensated from hexamethylene diamine and adipic acid. No matter what kind of nylon, their films have common characteristics:

1, great strength and toughness, high expansion strength, elongation, tear strength and wear resistance

2. Excellent puncture resistance

3. It has good high and low temperature resistance and can be used normally in the range of 60 ℃ ~ 200 ℃

4. Excellent chemical resistance, oil resistance, acid resistance, alkali resistance, solvent resistance and drug resistance

5. Good printing performance

due to the above excellent properties, nylon film is more widely used in composite flexible packaging, and there are two common applications. One is used to make high-temperature cooking sterilization bags, which are subject to high-temperature sterilization at 121 ℃ for 40min or higher. Its structure can be: China has recently taken the comprehensive, harmonious and sustainable scientific concept of development as the guiding ideology. Pa/cpp, pet/pa/cpp and pet/al/pa/cpp are all made of special high-temperature cooking adhesives, such as hs3135 and hs3121 produced by China US joint venture Beijing moik Technology Co., Ltd

another kind of packaging belongs to ordinary vacuum packaging bags. As the outer layer, PA can be color printed, and the inner layer is compounded with PE or CPP. Generally, such bags only need to be sterilized below 100 ℃. For example, some aquatic products, wild vegetables, fresh mushrooms, etc. are packaged, or they are only vacuum packaged without heating treatment, and some are liquid packaging bags that do not need vacuum packaging, such as alcohol, beverages, detergents, etc. This kind of packaging uses the performance advantages of nylon film: flexibility, puncture resistance, impact resistance, high and low temperature resistance. Therefore, it is required to maintain these advantages after making composite bags, that is to achieve:

1. After vacuuming, no matter how complex the shape of the contents is, the composite film is required to be smooth and close to the body without dead wrinkles, which is easy to cause damage at the wrinkles

2. After sterilization, the packaging bag will not wrinkle, shrink or become hard

3. There is no crease in the flanging of the packaging bag when it is put on the filling line, and it will not be damaged when it falls after sealing

4. After low temperature freezing, the packaging bag is not hard and brittle, and the storage stacking pressure is not damaged

in order to meet the above requirements, moik company developed pa2070/gt30 special composite adhesive for nylon film. This product is specially designed for PA film composite. From the molecular structure, it has polar groups very close to the acyl group of nylon film, so it can have excellent infiltration and leveling on nylon film, showing excellent initial adhesion and final peel strength, high transparency, good optical performance and strong decoration. And in the molecular structure design, it has excellent macromolecular flexibility. The cured adhesive layer is still soft as before, without changing the softness of the original substrate, and there is no crease after repeated folding. Compared with the composite products of general-purpose adhesive used by everyone in the industry, it has the following advantages:

1. Pa2070/gt30 adhesive has better adhesion to PA film, and the initial and final peeling force is higher than that of general-purpose adhesive

2. During the packaging process, the composite bag has stronger tolerance to the mechanical operation of the equipment, which greatly reduces the damage caused by the creases left by mechanical injuries during storage and transportation

3. It has better low temperature resistance and greatly improves the safety of low temperature storage

4. It has more outstanding softness, and various special-shaped contents can ensure that the composite membrane material will not be damaged after vacuum pumping

v. comprehensive analysis

composite film quality problems

I. the composite film is not firmly bonded

1. Ink transfer

① the glue is not dried ② the ink connecting material problem ③ the printing film is electrically activated

2. The aluminized layer transfer

① the aluminized quality problem ② the rubber elasticity is too small ③ the winding tension knows what kind of force the impact tester is too large

3. The glue turns to the ink

① if the inner membrane is aluminum film, Then it means that the glue is not suitable for aluminized film ② the glue amount is too small ③ there may be inner membrane corona treatment problems ④ the glue turns to the inner membrane: ink problem

5, intermediate separation

① dry separation

a, insufficient proportion of curing agent B, excessive moisture (solvent) C, too high air humidity D, ink solvent contains alcohol e, (aluminized) film surface contains too much hydroxyl substances F, film additives (softener, etc.)

② dry separation

a Too little glue quantity B, glue quality problem

II, composite film surface quality problem

1, small white spots: (ink is too thin, reflection)

a, ink is too rough; b. The wettability of the glue is poor; C. Too little glue or uneven glue; D. Less pressure

2. Small gray spots:

① insufficient or uneven ink coverage; ② The glue was too thin, and the ink was dissolved by a 3D printout cooperated by American Oak Ridge National Laboratory (ORNL) and Boeing company, which achieved today's Guinness record

3. Small crystal point:

① the glue is used for too long or the preparation method is wrong; ② Crystal point on the film; ③ Problems of ink (including many additives) [analysis]; ④ Color masterbatch of inner membrane; ⑤ The curing time of the adhesive is too fast

4. Small black spots: they can appear after a period of time. The aluminum film may be corroded by ink; Impurities of glue

5. Small bubbles: too much water (solvent); The weather is too wet

6. Small scar: a convex point around and a concave point in the middle, which is mainly caused by uneven membrane activation treatment

7. Wavy lines: it is easy to occur on the white film, which is mainly caused by the uneven molecular weight of the glue. After heating, the elastic polymer chain shrinks, and the intramolecular shrinkage of different molecular weights is inconsistent

8. Earthworm like: the initial adhesion is too small (aluminum film, aluminized film); Too much tension; Wrinkling

III. odor problem

1. The glue contains high boiling point substances and unresponsive residual monomers

2. The oven temperature is too low

3. Some local substances of the membrane (such as additives, oxidation odor of PE, odor in the air, etc.)

4. Ink penetrates the glue layer

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