Preliminary formula design of 1. 1
(1) According to the overall design requirements of plastic products, a sample similar to the standard color sample was found as a reference. Whether the reference object is selected properly is directly related to the coloring effect. In order to find a better coloring reference, we should accumulate and prepare more colored plastic swatches or plastic pigments for reference, and at the same time organize our own experience and lessons in color selection into corresponding coloring formulas for reference.
(2) In the absence of reference, carefully observe and analyze the color, light, hue and brightness of plastic products (samples), determine the color attributes, and determine whether the color used is transparent or opaque, and whether it contains other special pigments (such as fluorescent pigments and metal pigments). ), and then color according to the Munsell color system.
(3) Repeatedly compare the differences with standard color samples and reference objects in hue, brightness, shade, etc. On this basis, the formula of reference colorant was modified and the preliminary formula was drawn up.
Or design the required color according to Munsell color system calibration principle, and draw up the preliminary formula.
1.2 Adjust the formula according to the preliminary formula, carry out the physical color test, and compare the prepared color sample with the standard color sample and reference substance to further adjust the color formula. Then real samples are prepared according to the adjusted formula for comparison,
Then adjust the formula and repeat it for many times until the color tone of the real sample is the same as that of the standard color sample or reaches the satisfaction level closest to the standard color sample. Finally, determine the coloring formula for production. However, in actual production, the selected color is usually different from the color of plastic products, and the reason for these differences is largely the color weighing error. So how to make the color matching accurate? How to keep the color matching consistent in continuous production?
The accuracy of color matching is based on the selection of accurate pigments (dyes). The selection of pigment (dye) is based on the understanding of product effect and the observation of samples. The understanding and observation of samples depends on the experience and skills of color matching personnel. At present, many units use instruments to match colors, but some units still use manual visual inspection to match colors. Although the manual visual color matching method is simple, it requires rich experience of visual personnel. When two objects are viewed under the same light source (such as sunlight), their colors may be different. Similarly, for an observer, the colors of two objects may be exactly the same; For another observer, it may be different. We call these two objects allotropes or allotropes, and some of them are allotropes or allotropes. If two objects are required to look the same under any light source, it means that the spectral reflection curves of these two objects must be the same. This color matching is called unconditional color matching or unchangeable color matching. Constant color matching requires the use of the same colorant in the color matching sample. It is impossible to adjust the color of plastic to the same degree of color matching. There are many reasons for this, for example, the dispersion degree of the same pigment in different plastics is different; In a kind of plastic, sometimes it is necessary to decolor or color-adjust to remove other colors in the original plastic; In another plastic, this adjustment may not be necessary. Knowing these situations, we know fairly well in the actual color matching process and don't pursue unchangeable color matching. Since all the colors we match are variable, which condition should be taken as the standard? This requires specific analysis of specific issues. The principle is to observe the color matching by simulating the final use environment of the product as much as possible. If the product is finally used outdoors, you should also choose the color under natural light when matching colors. 2. 1 visual color matching
An experienced colorist must know the colorant he needs before mixing colors. To master the general rules of mixed coloring of colorants, we should also have a clear understanding of the properties of colorants used, such as hue, shade, fluidity, heat resistance, weather resistance and chemical stability. , accumulate representative plastic coloring samples and color matching. Before finding a suitable colorant formula, a lot of experiments must be carried out, and the same color must be blended repeatedly until the desired color is obtained. Obviously, visual color matching is a trial and error method, which is not very scientific. Because this method is simple and practical, it is still widely used. But this method is time-consuming and requires the operator to have rich experience, otherwise it is difficult to operate.
2.2 Instrument color matching
Instrument color matching is based on visual color matching. This method uses measuring instruments such as spectrophotometer to replace the functions of human eyes and brain. The trial and error process of color ratio is carried out by computer simulation, and there is no actual mixing of plastics. The operator only needs to measure the reflectivity, that is, its standard value, and choose pigments for color matching. By adjusting the concentration of color pigment, the measuring system is consistent with the standard conversion value. If the pigment selected by the operator is reasonable, the system will output a formula in the form of mass fraction, and then convert the percentage formula into mass ratio.
If we know (qualitatively) which formula of colorant is used in the sample, the computer can easily calculate the actual dosage of various pigments (dyes) in the formula. However, the formula of the colorant used in the sample is usually unknown. In this case, the chromaticity coordinates of the sample can be used to match the colors. There are many analytical and empirical relationships for selecting suitable colorant formulas and determining the concentration to be applied to each formula. The establishment of these relationships requires a lot of calculation. Using a computer can shorten the whole color matching process to ten minutes.
A color can be made from several formulas containing different pigments. The performance characteristics and components of these formulas are different from each other. Using color matching instruments and computers, we can get a variety of formulas of a color for color matching operators to choose, and see whether it is more economical to use a small amount of expensive organic pigments or a large amount of cheap inorganic pigments, so that people have a wider choice.
In addition, the instrument color matching and visual color matching of fluorescent substances are very difficult, because fluorescence is a new variable, and different results may appear when comparing two samples under different light sources. Not only the light source will affect the observation of the sample, but also the angle between the incident light and the observation position will affect the observation of the sample. According to thermal properties and processability
Thermoplastic: It softens when heated and can be molded by repeated heating.
Such as polyvinyl chloride plastic, polypropylene plastic
Thermosetting plastics: After being cured by heating, they cannot be melted by heating.
Such as phenolic plastics, urea-formaldehyde plastics
Divide by purpose
General purpose plastics: large output
Such as polyethylene, polypropylene, polyvinyl chloride
engineering plastics
Such as polycarbonate, polysulfone, polyphenylene ether, polyamide and polyoxymethylene.
special plastics
For example, medical plastics, conductive plastics and high-temperature resistant plastics. In order to facilitate the recycling of plastics, the Society of the Plastics Industry, Inc. (USA) put forward a label system that classifies plastics by types: "synthetic resin identification code" (usually translated as "plastic material code" or "plastic code"). The recyclable plastic container will be labeled with a triangle surrounded by three arrows, and the label will indicate the type of plastic.
China's national standard (GB 18455-200 1) stipulates that plastic packaging products or plastic containers with volume/volume exceeding 100 ml must be visually labeled with plastic recycling labels:
Logo abbreviation name purpose
PET polyethylene terephthalate, also known as polyester, is usually in Bote bottles.
HDPE high-density polyethylene is commonly found in cosmetic water containers, bottles and plastic bags in supermarkets.
PVC and PVC are common in pipes, outdoor furniture and raincoats.
LDPE low density polyethylene is often used for hose packaging of toothpaste or facial cleanser.
PP Polypropylene is commonly found in bottle caps, straws and food boxes of microwave ovens.
PS polystyrene is divided into unfoamed and foamed. Unfoamed styrofoam is common in some beverage containers (such as Yakult); Foamed foam rubber, commonly known as foam rubber, is often used to package rubber particles, disposable insulating plastic cups, frozen meat containers, lunch boxes and so on.
Other recyclable plastic products include polymethyl methacrylate (PMMA), polycarbonate (PC), polylactic acid (PLA), nylon, glass fiber reinforced plastic (FRP), biaxially stretched polylactic acid film (BOPLA) and so on.
Unfortunately, the recycling of plastics is not easy, and the implementation effect is not satisfactory. Compared with metal recycling, the biggest problem of plastic recycling is that it is difficult to sort automatically by machine, and the process involves a lot of manpower. In addition to containers usually made of a single plastic, many plastic products are assembled from a variety of different materials, and the cost of disassembling them may be higher than that of recycling plastic. In addition, some plastics recycling has no economic value, such as expanded polystyrene. This kind of plastic waste is usually buried or burned.
At present, the proportion of recycled plastics in the United States is very low, only 5%. Knife, fork and spoon made of degradable starch plastic. Main products: biodegradable plastics
Decomposable plastics will decompose in the sun. Starch has also been added to plastics to make it more biodegradable, but the decomposition is still incomplete. Some people use transgenic bacteria to produce completely biodegradable plastics, but the cost is still high. BASF has developed a biodegradable plastic called Ecoflex, which is used in food packaging. Due to the cost problem, the above degradable plastics are rarely used. However, this kind of plastic must be exposed to the air to decompose, so if it is buried, it will still lead to the problem of solid waste.
Plastic manufacturers often vaguely refer to the product as resin on the packaging, even though it is obviously sperm/artificial resin/synthetic resin. Ordinary people are easily misled into thinking that it is natural resin, so they can buy and use it with confidence. Many manufacturers do not clearly list all kinds of harmful chemicals added when manufacturing products.
Due to the mass production of plastics, low price and many color choices, everyone also uses plastic products in large quantities, so that it is often inappropriate to use plastics without knowing the actual characteristics of some plastics. For example, some plastics can't be heated or used to store acidic drinks and food, and some plastics can't be exposed to the sun, otherwise the ingredients will be released unsteadily. Because there is no immediate danger, various harmful substances in plastic products have entered and polluted the human body from different ways, that is, diet.
Plastic polyethylene, polyvinyl chloride, polystyrene, polyvinyl alcohol, polypropylene, polyacrylic acid, polybutene, polyisobutylene, polysulfone, polyoxymethylene, polyamide, polycarbonate, polylactic acid, polytetrafluoroethylene, polyethylene terephthalate, epoxy resin, phenolic resin and polyurethane.
Synthetic rubber, cis-butadiene rubber, styrene-butadiene rubber, nitrile rubber, chloroprene rubber.
Synthetic fibers include polypropylene, polyester, nylon, acrylic, spandex, vinylon, nylon, polyester and kevlar.