What you need to know about spray-free materials and processes.

The following is an introduction to the characteristics of spray-free materials, technical difficulties, and how to use them in design.

Strictly speaking, paint-free materials should be defined as surface-treatment-free aesthetic materials. With the tightening of environmental protection policies, the environmental awareness of product development and manufacturing enterprises has increased, as well as the unremitting efforts of industry practitioners. In view of the fact that it does not need to be sprayed, it can effectively reduce the cost of products, and it also has a variety of color matching effects without spraying. In recent years, spray-free materials have gradually become the preferred solution for product design, ID, etc. in the fields of home appliances, automobiles, 3C, and 5G.

1. Definition of spray-free materials

Without spraying, the "beautiful" appearance effect required for painting can be achieved directly by one-time injection molding. It is an environmentally friendly and low-VOC product; appearance effects include: high-gloss and brilliant spray-free effect (high-gloss material, piano black material, ceramic white), Pearlescent effect, marble effect, metal texture effect, etc.

Second, the technical difficulties of spray-free materials:

Difficulty 1: Surface defects of products (generation of weld lines)

The buildup of aluminum pigment at the intersection of the melts (resulting in visual differences in the product due to different densities in different parts of the sample) produces weld lines.

Generation of flow marks

The directional shear of the injection screw causes the aluminum pigment to orient on the surface of the material, resulting in flow marks; the existence of weld lines and flow marks is the "biggest obstacle" restricting the application of spray-free materials.

Metal texture series of spray-free materials can be applied to PP, ABS, PC, PMMA/ABS, PC/ABS and other substrate products. Because of its excellent appearance, excellent cost advantages and environmental protection performance, it has gradually replaced spray materials.

Difficulty 2: High requirements for mold design and molding process

The forming molds and processes of ordinary materials cannot meet the normal forming requirements of spray-free materials

Difficulty 3: Strict formulation design and raw material selection

The main difficulties of the problem are:

1. Selection of aluminum pigments;

2. Selection of metal aluminum powder (particle size and division) and surface treatment;

3. Raw material selection (material fluidity/material gloss/material transparency);

4. Formula design (material compatibility/material properties/material stability/material scratch resistance).

3. Solutions

Faced with the industry problems of flow marks and weld lines in spray-free products, the Sunflower R&D team proposed 2 solutions:

1) Launched a series of metal texture-free spraying materials to meet the complex structure requirements of customers, without the need for customers to re-open or change the mold; achieve brilliant colors, rich high-gloss effect, high oiliness, high gloss and other advantages, can be used in various fields.

2) Provide customers with suggestions for process adjustment and improvement of mold structure, such as using new processes such as "quick cooling and rapid heating", "in-die cutting" and "vibration feeding" to improve flow marks and weld lines.

4. Recommendations

Before the spray-free product is carried out, it is generally necessary to understand whether the characteristics of the material can be matched with the product. For the presentation of the final effect of the key mold, it is necessary to learn to judge whether the structural part is suitable for this spray-free material effect.