Study on the Selection of Additives in Low-odor Interior Wall Latex Paint

XU Jin-zhi1 , ZHANG Jin-lian2 (1.Shanghai Zhongnan Building Materials Co., Ltd., Shanghai 200030, China; 2. Shanghai Haochang Fine Chemical Co., Ltd., Shanghai 201100, China)

Abstract: The odor sources of interior wall latex paint are studied. A formula of interior wall latex paint with low odor is designed by selecting main additives like pH regulators, film forming additives, freeze-thaw stabilization agents, defoamers and preservatives etc.

0 Preface

Interior wall latex paint is generally welcomed because of its beautiful and practical, simple decoration effect , and is the mainstream of interior wall decoration. Despite 2537- HJ 2014, GB 18582-2008 standards for volatile organic compound content (VOC) and hazardous substances has been restricted, but low VOC does not entirely mean low odor, odor substances often means harmful substance , and subtle changes in smell may also happen to make our emotions become of even change our behavior in the case that we are unaware of.
The scent of fragrance is refreshing, while the stench is just the opposite. With the improvement of people’s consumption level and health awareness, higher requirements are placed on the decoration process and indoor odor. In recent years, low odor milk supply liquid has been relatively full, and therefore intensive, select the appropriate aids to design a lower odor interior latex paint formulations it has important practical significance.This article focuses on the pH adjusters, film-forming aids, freeze-thaw resistance stabilizers, defoamers, and preservatives in tanks that can significantly affect odor in interior wall emulsion paints. The taste is lower.

 1 Experimental part

1.1 Main raw materials and preparation

The raw materials and formulations used in this study for low-odor interior wall emulsion paints are shown in Table 1.

Low-odor interior wall latex paint formula (PVC = 80%)

1.2 Odor comparison

Odor on the coating material and the current is no corresponding technical specifications and standards, the present study international practice selection 5 gas odor panelists were independently scored according to Table 2. This five odor panelists were 45 years of age, there is no smell of disease, and do not smoke in the office working smoke personnel control point table for training and later the smell test, it will have to be the arithmetic mean of the values to arrive at the smell of points value.

Scoring score

1.3 Coating performance testing

According to GB / T 9756-2009 “synthetic resin latex interior wall paint” and HJ 2537-2014 “Environmental Labeling Products aqueous coating” in the interior wall paint and topcoat standard method for detecting properties of interior latex paint can and hazardous substances Limited.

 2 Results and discussion

The formulation design of low-odor interior wall latex paint should start from the selection of emulsions, additives and control of microbial contamination. Table 3 shows the interior coating characteristic data and common odor substances harmful compound, wherein the olfactory threshold is a person’s olfactory organ of a certain minimum amount of odorous substances detectable or most low concentration, the lower the value actuator odor The greater the effect.

2.1 Lotion and Odor

The odor of the emulsion mainly comes from its residual monomers and neutralizers. A general, styrene-acrylic emulsion because of the smell of residual styrene monomer larger much more. After the monomer removing process or other techniques to reduce residual monomers milk liquid to a lower odor; with ammonia as a pH adjusting agent is an emulsion will have a pungent smell of ammonia. In this study, a low- odor styrene-acrylic emulsion, which has been approved by the market , has a mass solid content of about 48% and a minimum film formation temperature (MFFT) of about 29 ° C to facilitate the screening of additives.

Odor substances common in interior coatings

2.2 pH regulator

Emulsions and additives in latex paints may contain ester functional groups, so controlling the pH value has a significant impact on the product’s storage stability, wetting, defoaming and antibacterial properties. Generally, latex paint should be controlled to be weakly alkaline. Strong alkalinity will accelerate the hydrolysis reaction, and when the pH value is greater than 9, it will make some sterilization and preservatives in the tank unstable. pH adjusting agents should be when volatilize rapidly after paint coating, or film coating will remain in the water resistance, and scrub resistance of the coating ring.Common pH regulators are sodium hydroxide, ammonia, and 2-amino -2-methyl-1-propanol. Because sodium hydroxide is not volatile, remain in the coating film so that the water is deteriorated, and the ammonia and 2-methyl-1-propanol because the excreta foul taste and criticized by others. AN130 is a low odor pH adjuster, which also has the function of helping wetting and dispersing, and the performance comparison with other pH adjusters is shown in Table 4.

Common pH regulators and their advantages and disadvantages

According to the formulation shown in Table 1 were added 1 part by mass AN130 and 2 -methyl-1-propanol, to adjust the viscosity at 100 KU (25 ℃), phase off viscosity and pH comparative data in Table 5.

Comparison of AN130 and 2-amino-2-methyl-1-propanol

From the data in Tables 4 and 5, it can be seen that the pH and viscosity of the paint adjusted using the low-odor AN130 are basically stable.

2.3 Film-forming aids

After GB 18582—2008 “ Limits of Hazardous Substances in Interior Decoration Materials and Interior Wall Coatings ” and HJ 2537—2014 “Environmental Labeling Product Technical Requirements for Waterborne Coatings” and other standards have been promulgated and implemented, film-forming aids are developing towards higher boiling points. But high boiling products do not mean low odor. The boiling point of the alcohol esters -12 deg.] C is more than 250, but the odor of its own and is not pleasant, odor after construction and long duration. This research study this selection CL3101 colorless, odorless and biodegradable co-deposition agent, as a reference to the object -12 alcohol esters, where the smell are shown in Table 6.

Comparison of film forming additives performance and odor

In the minimum film formation temperature (MFFT) of 29 deg.] C low odor phenylpropyl milk added different amounts of liquid alcohol esters 12 and CL3101, MFFT is measured for reduction data shown in Figure 1. Using CL3101 to add 4% by mass of the emulsion can reduce its MFFT to 5 ℃. Considering the film forming properties of the powder affect this study was selected using CL3101 coalescent added in an amount of 4.5% emulsion of an amount (mass fraction).

Adding amount of film-forming aid and minimum film-forming temperature

2.4 Defoamer

From the economic point of view, the current consumption interior latex paint used in the foaming agent or in a mineral oil-based, and a commercially available mineral oil defoamers such as if a selection of petrochemicals base crude oil, hydrogenation and deodorization without workers Arts and treatment, there will be a pungent odor. Herein, and additional selection DF681F two commercially available mineral oil defoamers to compare its appearance and odor case conditions shown in Table 7. Wherein DF681F relatively very low odor, are selected from the selection in the present formulation.

Defoamer screening

2.5 Freeze-thaw resistance stabilizers

Traditional latex ethylene glycol, propylene glycol as a freeze-thaw stabilizing agent, but because of its low boiling point, is counted and may be VOC content by gradually eliminated and replaced by a polyethylene glycol, FT10Xtrim like can provide a high freezing Non-VOC additive with melting stability. Table 8 gives these products relevant comparative data, it can be seen polyethylene glycol, FT10Xtrim gas odor is very low. Add 1% by mass of polyethylene glycol, FT100 Xtrim, and blank samples to perform the freeze-thaw test in accordance with the mixing ratio in Table 1. If the coating is normal , test its viscosity. The results are listed in Table 9. It can be seen that adding 1% of FT100 Xtrim can go through 5 cycles.

Comparison of common freeze-thaw resistance stabilizers

2.6 Preservatives in tanks

Interior Latex is rich in moisture and nutrients, microbial matter in which it is easy to grow and multiply, causing paint delamination, smelly; in hot, humid areas and / or seasons, such microbial contamination of The higher the probability of occurrence, the higher the requirements for preservatives in the tank. Low gas odor interior latex paint should be free of formaldehyde and formaldehyde releasing selected body preservative agent, the immediate and long-term preservation efficiency considerations, the choice of RS 0.1% and 0.1% MBS complex.

2.7 Full performance test

Based on the selection of 2.2 ~ 2.6, in Formula Table 1, 1 part of AN130 for pH adjuster, 5 parts of CL310 for film-forming aid, 2 parts of DF681F for defoamer , 5 parts of FT100 Xtrim for freeze-thaw stabilizer, can preservation agent and 1 part by RS MBS, low odor interior latex paint formulation, its full term performance test results are shown in Table 10.

Low odor interior wall coating test results

As can be seen from the test data, the choice of these additives and low odor addition amount, design of products to GB / T 9756-2009 inner wall paint First grade requirements, but also fully meet the requirements of the HJ 2537-2014, especially Its VOC content is very low and it is formaldehyde-free.Use the low-odor product and two well-known low-odor interior wall paint rollers to apply two coats to the interior wall of a room with a building area of ​​about 30 m2, and score the odor 2 hours after coating and 2 days after coating. The odor comparison data after the coating is opened is shown in Figure 2.As it is seen from comparison of FIG. 2, whether the rear interior paint cans, applying the work H 2, D 2 after the odor were significantly lower than comparison samples.

Odor test and comparison

3 Conclusion

Latex is related auxiliaries sieve odor five inspectors selected to prepare low odor interior paint, the performance reached GB T-2009 / Requirements “synthetic resin latex interior wall paint” in which the VOC and harmful substances It is far lower than HJ 2537-2014 “Technical Requirements for Environmental Labeling Products for Water-based Coatings”, and the odor is significantly lower than the commercially available samples.

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