Development and Application Disussion of Odorless & Low VOC Environment Friendly Colorant for POS Tinting System

Huang Jun (Nippon Paint Investment Co.Ltd.Shanghai,201204,China) Tian Hong (Nippon PaintChinaCo.Ltd.Shanghai,201201,China

Abstract :The development history and future trends of colorant for POS t inting system were introduced. Based on analysis about POS colorant odor and resource of VOC,the soluti ons of odorless and low VOC were given,and actual application requirements of odorless & low VOC environment friendly colorant for POS tinting system were discussed.

retail store tinting system as a A new marketing model of water-based architectural coatings in China began in 2000. Its appearance not only meets and drives consumer demand and pursuit for decorativeness and color personalization of coatings, but also increases the market share of paint makers for color systems in retail stores. In the following years, large domestic and foreign paint manufacturers have launched their own retail store color matching systems, and established color matching centers in large and medium-sized cities across the country. Retail store color matching systems have become a weapon for coating manufacturers to promote and occupy the market.
The composition of retail store coloring system includes base paint, color paste, color mixing machine, shaking equipment, color formula, color management software and sales tools. The color paste for the color system of retail stores is also called POS (Point of Sales) machine color paste. It is one of the most important cores of the color system. The color paint that consumers buy in retail stores is used in latex paint. It is made by adding color paste to POS machine. In recent years, with the government ’s emphasis on environmental protection and increasing consumer environmental protection requirements, China ’s requirements for the limit of harmful substances such as VOCs (volatile organic compounds), free formaldehyde, and benzene in water-based architectural coatings have continued to increase (see table). 1) Green environmental protection coatings with functions such as “formaldehyde resistance”, “net taste”, “low VOC”, “ultra low VOC”, “environmental protection” have gradually become mainstream products. Now the coating market has appeared to be more environmentally friendly “No Additive” Latex Paint Products. “Non-additive” latex paint can only be used in conjunction with the corresponding functional colorant to call up the true “additive-free” colorant. In this case, there are higher requirements for the environmental performance of colorant for POS machines. Green environmental protection has become the research and development direction of color paste for POS machines.

Limitation of harmful substances in water-based architectural coatings in different periods in China
Limitation of harmful substances in water-based architectural coatings in different periods in China

1 Development history of machine color paste
The traditional paint coloring is to add pigment powder directly to the paint, or simply make the pigment into a slurry, and then add it to the paint to color the paint. There are many disadvantages to this, such as the need to correct the color multiple times; the same color Poor reproducibility; high production costs for small batches, high waste, and serious environmental pollution; lack of professional processes and technologies, coarse pigment particles in colored paints, and poor tinting power, resulting in rising coloring costs. With the refinement of the market division of labor, companies specialized in the production of pigment pastes have emerged. In 1949, the California ink company (formerly known as Hess) introduced the concept of pigment pastes into the coatings industry. Paint manufacturers can simply make pigment pastes to produce various pastes. This kind of colored paint brings great convenience to customers. However, the colorant at this time does not have universality, and it is selective to the film-forming materials of the coating, which limits its scope of use. At the same time, ordinary colorants do not strictly control the color and intensity of the pigments, causing batches between colorants. The quality is not stable enough, and multiple corrections are still required during the toning process.
After the end of the Second World War, the paint industry that was waiting to be developed rapidly developed, and new synthetic emulsion products continued to emerge, laying the foundation for the development of modern architectural coatings, the diversification of paint varieties, and people’s personalized needs for colors. This makes it difficult to achieve a win-win situation in terms of cost and customer service. The production of colored paint requires a more economical and convenient production process. In 1952, the American Hess company developed the world’s first set of Colortrenda general-purpose mechanical coloring pastes, which opened the history of mechanical coloring pastes, and introduced the system to Europe in the 1960s. European countries applied the mechanical coloring process In the practice and application of coating production, the mechanical tinting system has been greatly developed.
The production and development of machine color pastes originate from people’s diverse color needs and the diversification of coating systems; dry powder pigments for machine color pastes need to undergo strict screening, and their color, color intensity and rheology have all passed Strict control, stable batch-to-batch quality, can be miscible with different coating systems; the use of mechanical color matching technology, to achieve direct color matching and color matching at long-distance retail stores, to maximize consumer satisfaction with color personalization, The pursuit of diversification, as well as the requirement of timely and unlimited order quantity.
Since the 1990s, China’s architectural coatings industry has developed rapidly. Facing such opportunities, large foreign coatings companies have sought opportunities to enter the Chinese market, and with them the world’s major pigments, colorants, and coating additives. Suppliers of raw materials and other materials have created conditions for promoting the new color system. In 1994, the German Degussa company began to promote the modern color system in China. In 1997, CPSColor entered the Chinese market and launched its water-based universal color paste “Monicolor”. In 1998, Degussa established an office in Shanghai. , Ai Shi Shi, Jia Bao Li and other companies began to evaluate the color system, since then modern color technology has developed rapidly in China. The application of color paste spreads all walks of life in coatings, plastics, printing, papermaking, textiles, etc., and brings colorful colors to our lives.

2 Classification and characteristics of machine color paste
Color paste is a colorant formed by pigments or pigments and fillers dispersed in different media, also known as pigment preparations and pigment concentrates. According to different media, color pastes are divided into water-based color pastes, oily color pastes, water-oil color pastes, etc .; according to different addition methods, they can be divided into machine color pastes and factory color pastes. Machine color pastes are divided into retail store color pastes and machine factory color pastes according to the place where they are used, and usually include 10 to 16 color pastes. Retail store colorants are mainly used for small batch coloring in retail stores. Compared with factory colorants, they have the following characteristics: First, they are specially designed for mechanical coloring and are injected in a volumetric manner. The stability needs to be optimally optimized to meet the requirements of the color paste drop accuracy, and the minimum injection accuracy can be achieved to 0.08 mL; Second, the color difference and color intensity are strictly controlled. Generally, the color difference is controlled within 0.5, and the color intensity is controlled within ± 2%, which guarantees the batch stability of color paste, and can achieve the accuracy and reproducibility of color mixing. Third, it has versatility and has good compatibility with water-based coatings of various systems. Fourth, Appropriate color density. If the color density is too high, it is easy to reduce the color accuracy; if the color density is too low, it is difficult to adjust the dark color, and the cost is increased; fifth, the selection of pigments is high. It is required that the light resistance, weather resistance, heat resistance, solvent resistance, acid and alkali resistance, and migration resistance of the pigments all reach a certain level.
The machine factory color paste is suitable for the large batch coloring of the factory / warehouse production coloring system. It has a high color density, strong tinting strength, and low coloring cost. The injection method can be either volume or weight, and it also has The characteristics of machine color pastes are higher than that of factory color pastes in terms of batch stability, storage stability, and rheology of color pastes.
At present, the major manufacturers of machine color pastes in the domestic market are CPS Color, Degussa, Clariant, AkzoNobel, and CCA abroad. Among them, CPS and Degussa are now affiliated with Chromflo; domestic ones include Suzhou Shiming, Guangzhou Cody, etc .; color The brands of the pulp include “ColortrendaPlus” by Degussa, “Dramatone” by AkzoNobel, “Hostatint TS 600” by Clariant, “NovoColor” by CCA, and “NV” by the world name.

3 Environmental requirements for color paste with low VOC and environmental protection for POS machines
3.1 Free of APEO
APEO (alkylphenol polyoxyethylene ether compounds) is widely used on the surface due to its good wetting, dispersing, emulsifying, and compatibilizing properties. Active agent. Studies have shown that APEO is slow in biodegradation, and the biodegradable metabolites NP (nonylphenol), OP (octylphenol) and NPEO (nonylphenol polyoxyethylene ether) and OPEO (octylphenol polyoxyethylene ether) belong to Environmental hormone chemicals can interfere with the normal secretion of human hormones, leading to a decrease in male sperm counts and abnormal reproductive organs. China ’s HJ 2537-2014 “Environmental Labeling Product Technical Requirements for Waterborne Coatings” implemented on July 1, 2014 clearly stipulates that APEO cannot be artificially added to products.

3.2 VOC content
Tested in accordance with the method of Appendix A of GB 18582—2008 “Limits of Hazardous Substances in Interior Decoration Materials and Interior Wall Coatings”, VOC (volatile organic compound) content <2 g / L (minimum detection line).

3.3 Free formaldehyde content
According to the method of Appendix C of GB 18582—2008 “Limits of Hazardous Substances in Interior Decoration Materials and Interior Wall Coatings”, the free formaldehyde content is <5 mg / kg (minimum detection line).

3.4 The total amount of benzenes is
tested in accordance with the method in Appendix A of GB 18582—2008 “Limits of Hazardous Substances in Interior Decoration Materials and Interior Wall Coatings”. The total amount of benzene, toluene, xylene, and ethylbenzene is <50 mg / kg (minimum detection line).

3.5 The content of heavy metals was
measured according to the method of Appendix E of GB 18582—2008 “Limits of Hazardous Substances in Interior Decoration Materials and Interior Wall Coatings”. The soluble lead content was <0.1 mg / kg, the soluble cadmium content was <0.8 mg / kg, and the soluble chromium content was <2 mg. / kg, soluble mercury content <2 mg / kg, are the lowest detection lines.

4 R & D of low-VOC environmentally friendly POS machine color paste
4.1 Realization of net taste
POS machine color paste is generally composed of water, surfactants, humectants, rheology modifiers, anti-fungal fungicides, defoamers, pH adjusters, pigments and fillers. Among them, there may be surfactants that may contain VOC components. , Humectants, rheology modifiers, pH adjusters, etc., the use of VOC-free or low-VOC additives can effectively reduce the smell of color paste. However, the size of the odor is not completely proportional to the level of VOC. Some ingredients are used in a small amount in the formula and do not contain VOC, but they have an unpleasant odor. For example, since the production, storage, application, antiseptic and other processes of color paste require a weakly alkaline environment, a pH adjuster needs to be added to the formula to adjust the pH. Commonly used pH regulators are alkanolamines and ammonia. Ammonia is not an organic solvent and is not a VOC, but it has a strong irritating ammonia odor that makes people feel uncomfortable. Therefore, in order to achieve the net taste effect, in the selection of raw materials, we should not only consider using VOC-free and low-VOC products, but also avoid using some raw materials that have odors or unpleasant odors, and control the smell of color paste from the source.

4.2 VOC control
GB 18582—2008 “Limits of Hazardous Substances in Interior Decoration Materials and Interior Wall Coatings” defines volatile organic compounds (VOC) as: at the standard pressure of 101.3 kPa, any organic with an initial boiling point lower than or equal to 250 ° C Compounds. The VOC of POS machine colorant is mainly derived from the moisturizer and functional additives in the formula. Due to the particularity of its use, it is necessary to add about 10% to 20% of a humectant in the formula to prevent the color paste from drying up and blocking the nozzle. Most of the early color pastes for POS machines used ethylene glycol as a humectant. The boiling point of ethylene glycol is 197.3 ° C, which is a VOC. It is a low-toxic substance, but it is harmful to the body after inhalation, ingestion, or absorption through the skin, which can cause bronchial inflammation. , Cramps, renal failure, etc.
In the late 1980s, due to environmental considerations abroad, ethylene glycol was gradually replaced by propylene glycol, which is less toxic. Propylene glycol is slightly toxic and non-irritating to the human body, but its boiling point is only 187 ° C, which is still a VOC. With the application of low relative molecular weight polyethylene glycol as a humectant in POS machine color pastes, it is possible to develop low VOC POS machine color pastes. The hydroxyl group in polyethylene glycol can be well combined with water molecules, has good moisture retention, and polyethylene glycol is non-toxic and non-irritating. The most important thing is that its boiling point is greater than 250 ° C, which is not counted as VOC .
Functional auxiliaries include surfactants, rheology modifiers, anti-mildew fungicides, defoamers, pH adjusters, etc. in the formulation. The role of surfactants in colorants is to provide wetting, dispersing, stabilizing, and improving color development. Due to its versatility, POS machine color pastes contain more surfactants. The VOC content of surfactants has a greater effect on the VOC content of color pastes. Rheology modifiers, antifungal fungicides, Foaming agent, pH adjuster and other functional additives are not used in the formulation in a large amount, and have a small effect on VOC. Many additives companies have launched low VOC additives for water-based systems, and it is easy to choose the right product.

5 Performance requirements for color paste with low VOC environmental protection POS machine color paste
5.1 Ideal color acceptance
Ideal color acceptance is the key to the successful use of machine color paste in POS color mixing system, which determines the quality and construction performance of colored paint . The color acceptability of POS machine color paste is judged by testing its compatibility with commonly used emulsion type base paints and color development. At present, the commonly used emulsion types of commercially available latex paints are: pure acrylic, styrene acrylic, vinegar acrylic, VAE (vinyl acetate-ethylene copolymer), silicon acrylic, tertiary vinegar and polyurethane acrylic emulsions. The test method is as follows: Add the color paste to the base paint at 2% ~ 5% (V / V), mix with a full-automatic mixer for 3 min and 9 min, respectively, compare the color difference and tinting strength of the card and conduct finger research. Test, after room temperature self-drying, visually observe the color difference of 3 minutes and 9 minutes, and the color difference of the reference and non-reference points. If there is no obvious visible color difference, the color acceptability of the color paste for this machine is considered good. .

5.2 Excellent stability
5.2.1 Color paste storage at normal temperature, heat storage stability and freeze-thaw stability
Compared with ordinary water-based color paste, POS machine color paste has higher storage stability requirements, heat storage and freeze-thaw The post-color paste viscosity change, the presence or absence of precipitation and agglomeration, fluidity, and hue change directly affect the accuracy and reproducibility of color mixing. The color paste with excellent storage stability has no obvious change in viscosity after storage. The color difference before and after storage is ≤ 0.5, and the coloring power is 100 ± 2.

5.2.2 Stability of color paste in the tinting tank
The stability of the colorant in the toner tank is critical to the correct operation of the toner and color reproducibility. The color paste tank is usually equipped with stirring equipment. When the power is on, the stirring will automatically run at a certain time. If the color paste has poor defoaming properties or is easy to delaminate, agglomerate and settle, it will also cause deviations in the color accuracy. The change of the amount of colorant drop can effectively judge whether the colorant is stable in the tank of the color mixer. The volume drop of the colorant drop should be kept within ± 5%.

5.2.3 Batch stability of color paste

The batch stability of color paste is also one of the important factors affecting the accuracy and reproducibility of color mixing. When the color difference between color paste batches is controlled below 0.5, and the tinting power is in the range of 100 ± 2, the impact on color accuracy and reproducibility is small.

5.3 The addition of color paste will not have a negative impact
on the performance of latex paint. The effects of color paste on the performance of latex paint include dryness, viscosity change, water resistance, scrub resistance, acid and alkali resistance, and workability. Dark paint has a large amount of color paste added, which also has the greatest impact. The effect of color paste on the performance of latex paint can be judged by testing the dryness, viscosity, and resistance of dark paint.

5.4 Net taste effect
The odor of color paste includes the odor in the tank and the color after construction. At present, China’s coatings industry has not established relevant standards for color paste odor evaluation. The evaluation method is generally a non-quantitative olfactory method. The subjective impact is relatively large. At present, Nippon Paint has taken the lead in formulating the enterprise standard Q / OAEY 287-2009 “Net Emulsion Latex Paint (Low-odor Latex Paint)”. The color paste will eventually be added to the base paint, so this enterprise standard is also applicable. For odour evaluation of net color paste.

5.5 The green environmental protection
colorant is added to the base paint and becomes a part of the base paint. Its environmental performance will directly affect the environmental performance of the color paint. The country’s mandatory standard for interior decoration materials, interior wall coatings GB 18582—2008 “Interior Decoration Materials The Limit of Hazardous Substances in Interior Wall Coatings clearly specifies the limits and testing methods of hazardous substances. According to the GB 18582-2008 test method, it has been tested by a nationally recognized third-party testing agency. The test results of environmentally friendly colorants are shown in Table 2 and can be used as latex paint. Matching color paste for “No Additive” products.

Test results of color paste with low VOC environmental protection POS machine

6 Conclusion
With the continuous introduction of various environmentally friendly latex paints, as an important part of the coloring system of retail stores, colorants also need to keep pace with the times, and develop environmentally friendly colorants that can be used with environmentally friendly latex paints, so that consumers can consume them. Buy real environmentally friendly coatings.

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