Packaging Container Structural Design and Manufacturing - Plastic Containers (6)

Chapter 5 Surface Finishing and Coloring of Plastic Packaging Containers

Section 1 Plastic Surface Finishing

I. Overview

1. The definition of surface finishing refers to the fact that the original shape of the plastic container is not damaged, and the surface of the plastic container is obtained through a special process to obtain a smooth surface or to add a coating layer, a plating layer, a color pattern or a typeface, etc. Such special processing methods are collectively referred to as surface finishing.

2. The purpose of surface finishing is to mask molding defects, increase aesthetics, increase product value, and meet certain special performance requirements.

3, the role of surface decoration Decorative: improve the decorative effect, make up for manufacturing defects Functionality: to improve the surface properties

4. Surface Finishing Methods Mechanical Finishing Surface Finishing Metallized Surface Printing Technology

Second, mechanical finishing

Boring, grinding, polishing, rolling, sandblasting

Third, the surface finish on the surface of the plastic container coated with a flowing state of the paint, make it dry and hardened, the formation of a thin film to protect and beautify the product technology.
Common methods are spraying, roller coating and powder coating.

Fourth, the surface of the metallization in the plastic surface plating a solid layer of metal, so that the nature of the plastic to give metal technology.

Fifth, surface printing
1, surface hot stamping (hot stamping)
With the help of heat and pressure, the hot melt adhesive on the hot stamping foil is melted, and the decorative layer and the product are bonded together, so that the surface of the product presents various colors of patterns, patterns, characters, and markings.

2, screen printing (seal printing)
The decorative pattern consists of holes of different sizes, and the printing ink is passed through these holes and printed on the surface of the article to achieve the purpose of decoration.

3. Other printing technologies 1 Offset printing (flat printing): The graphic and non-graphic parts are in the same plane, and the ink and ink are repulsed by 2 gravure printing: graphic concave, non-graphic convex 3 convex: graphic convex, non-graphic concave 4 In-mold decoration: The printed transparent film is placed in the mold, and 5 electrostatic printing is applied during molding. Supplement: Surface treatment before surface printing Purpose: To introduce polar genes, covalent bonding force is large, hydroxyl is introduced, Removal of weak interfacial layer by carbonyl to increase surface roughness, increase micro contact area method: chemical solvent treatment, remove surface contaminants (with ethanol)
The flame treatment uses a certain mixture of gases and burns on a special burner. A surface treatment method in which the plastic is directly contacted with the oxidation flame of the flame and the plastic surface is modified.

Principle: Under the action of the oxidizing flame of flame, the plastic surface molecules are oxidized or decomposed to generate oxygen-containing genes such as hydroxyl groups, carbonyl groups, and unsaturated double bonds. The breakage and decomposition of the molecular chain change the microscopic geometry of the plastic surface and increase the surface roughness. At the same time, the high-temperature flame can also burn off grease, dirt, etc. on the plastic surface, thereby eliminating the weak interface layer on the surface.

Corona treatment, high frequency, high voltage, electric field, carbonyl,

Section 2 plastic coloring

First, coloring agent
1. Kinds of colorants Colorants are substances that change the color of an object or color an object that is otherwise colorless. 1 Pigment 2 dye

2, the requirements of the colorant 1 better dispersion 2 heat resistance is better 3 have a certain weather resistance and light resistance;
4 compatibility is better

Second, the method of plastic coloring

1, powder coloring (dry powder coloring)
Mix the colorant in the powder state directly with the resin
PE, PP, PVC, ABS

2. Paste Coloring Add colorants, dispersants, surfactants, and the like to a non-volatile liquid dispersion medium, mix and grind them into a color paste, and then use the color paste to mix with a resin to perform molding processing or granulation.

3, color masterbatch color masterbatch: containing a large number of color concentrates of colored plastic particles to be colored plastic particles and a small amount (1 ~ 10%) masterbatch, fully mixed, can be used for molding.

4, the coloring of the granular material The powdery coloring agent and the dispersant are uniformly mixed to form a certain granular material, and the granular material is used to color the plastic.