Ningbo Zhihua Chemical Co., Ltd. Zhizhong Xia, Leiguang Chen, Cainv Shen

 

Abstract: This paper gives a description to the status of leveling agents and the theory of R&D, focus on how Zhihua Chemical successfully develop the property and the application scope of active liquid leveling agent with its excellent performance under the guidance of R&D.

 

 It has no need to emphasis the importance of leveling agent, it play the role of salt in dishes as in powder coating industry fields. In recent years, powder coating has a rapid development of domestic market, the competition is quite fierce, which require the enterprises a better quality with lower cost price. This requires new functional agents to achieve this mission. The development of leveling agent has always catch the attention, in latest years, despite the development of leveling agent, just as cold dish refried, there is no much improvement, so a deep research to functional leveling agent is to be imperative

 

The liquid leveling agent supplied in current market is pure butyl acrylate copolymer.

The solid leveling agent market is uneven; there are three categories in total: (1) with epoxy as carrier (2) with polyester as carrier (3) fumed silica as the carrier. The dosage of leveling agent is upon the content of butyl acrylate in leveling agent. With the active content 15% wt in the formed two leveling agent, the dosage is 5%wt of total powder coating. The third kind has 60%-65%wt of active agent, and its dosage is about 1% wt of total powder coating. But in pursuit of higher profit, some manufactures and traders use cheaper fillers, i.e.: barium sulfate, cadmium carbonate as the carrier with some lubricating materials, which roused the power coating’s instability, caused a lot trouble to technicians, and it also lose the effect of the additives-- the minimum amount with the maximum effect.

These inferior leveling agent lead the false glory of powder coating market in a certain extend, but it damages the interests of powder coating manufactures in final, while some famous enterprises have use liquid leveling agents instead of solid leveling agent in Guangdong, and Fujian.

 

Powder additives manufacturers need to research and develop a leveling agent with high performance to regulate the market.

 

 

1. Taking the advantage of propenyl double bond polymerization, to graft some functional group on molecular bond of leveling agent butyl acrylate copolymer, some Common groups are hydroxyl, carboxyl, amine, etc., they can combine with epoxy groups as followed:

 

1. Leveling agent containing carboxyl combine with epoxy group:

2、Leveling agent containing hydroxyl combine with epoxy group:

3、Leveling agent containing amine combine with epoxy group:

Remark: R- PBA Poly (butyl acrylate) compounds

 

Epoxy group includes epoxy resin and TGIC in pure polyester

 

 The process of combination, enhancing the combination of leveling agent with resins, it can improve the leveling of resin, arise the adhesion, which is good for the integrity of coating surface.

 

Common monomers

 

 

The glass transition temperature of these functional monomers is higher than butyl acrylate, and the dosage should be below 5% wt of total, otherwise it can caused higher viscosity or higher formula ratio.

We can find the better functional monomer through research.

 

2. It can reduce the leveling agent’s viscosity through compound by an advanced surface active agent and n-butyl acrylate copolymer, it can also promote folwing, wetting and dispersion, improve adhesion and other deep functions, play a good role as synergism.

In domestic market today we are exploring this kind of functional leveling agent, such as hydrogenation of castor oil, polyethylene wax, EBS, etc. but it just stay the solid leveling agent, with weak influence, and overdose may cause a side effect.

 

In abroad market there is LA leveling agent, a fatty acid wax organic polymer. It has excellent performance used together with butyl acrylate copolymer, improving the wetting properties of coating base, promoting integration of resin and the fillers, enhancing the spreadability of powder coating and base. It is said that it can receive a smooth effect of coating surface as solvent powder coating.

 

Through hundreds of tests, and in accord with the above theory 1, we have successfully research and develop out PV99 high effective leveling agent. In accord with theory 2, we successfully research out high quanlity & reasonable price active liquid leveling agent.

 

 

Immediately active liquid agent enters the market, it received a high degree of recognition by famous powder coating manufactures in domestic market. It is a compound by advanced surface active agent K-300 and modified PHA.

 

Advanced surface active agent K-300, has followed properties suit for powder coating:

1. high temperature resistance, above 300℃, it can not evaporate, or decompose

2. Good stability, no chemical reaction with other additives or resins

 

As a functional leveling agent, this surface active agent has below properties:

 

1. Good compatibility, e.g. high organic fat-based has a certain compatibility with resin, pigments and polypropylene, and it’s the other polar group has a heavy affinity to the fillers.

2. A high degree of lubrication factor. In process of the powder coating to form the coating surface, it move to surface that forms a single-molecule layer to reduce surface tension and surface coating friction coefficient and to improve its anti-scratch performance.

3. Antistatic property. Surface active agent absorb water in air by hydrophilic group can produce polarization, which forms a thin pro-layer, producing a static leakage channel

4. Noninterference property. Leveling agents from different brands may cause interference, through test, this product has good noninterference property.

5. Enhancing flowing property. It can reduce the system’s viscosity, improve the powder coating system’s tension, giving a uniform and constant surface.

 

Modified PHA has a even uniform molecular weight, the lower volatile matter.

 

Technical specification for active liquid leveling agent

 

Appearance: Transparent liquid (atmospheric temperature)

Viscosity: 50℃/mPa·s        2500~4000

Active ingredient:  ≥98%

Volatile: ≤0.10%

 

Comparison between active liquid leveling agent and common-type solid leveling agent: (table 1)

 

Material Name	Mixed type（Flat Lighting）
	Formula 1	Formula 2	Formula 3	Formula 4	Formula 5	Formula 6	Formula 7	Formula8	Formula 9	Formula 10
	1	2	3	4	5	6	7	8	9	10
Polyester resin	270	270	570	570	525	525	470	470	5	5
Epoxy resin	270	270	/	/	/	/	/	/	550	550
TGIC	/	/	/	/	/	/	5	5	/	/
hydroxyalkyl amide	/	/	30	30	20	20	/	/	/	/
Active liquid leveling agent	/	6.5	/	6.5	/	6.5	/	6.5	/	6.5
Common-type liquid leveling agent	6.5	/	6.5	/	6.5	/	6.5	/	6.5	/
Gloss enhancing agent	10	10	10	10	10	10	10	10	10	10
D68 matting agent	/	/	/	/	/	/	/	/	50	50
extinction acrylic matting-resin	/	/	/	/	85	85	110	110	/	/
benzoin	3	3	3	3	3	3	3	3	3	3
BaSO 4	360	360	200	200	190	190	380	380	350	350
Rutile Titanium Dioxide	50	50	150	150	150	150	/	/	/	/
pigment	15	15	15	15	15	15	10	10	10	10
Tension of impact （kg*cm）	50	50	50	50	40	50	50	50	40	50
gloss（60°）	89	92	87	90	18	18	5	5	5	5
Flowing	Common	fine	common	fine	Common	fine	common	fine	common	fine
Clarity of coating surface	common	clear	pinhole	Clear no pinhole	Rough surface	Smooth surface and clear	Rough surface	Smooth surface clear	Rough surface	Clear smooth surface

 

Through large quantity of tests, we can get the conclusion that active liquid leveling agent has wonderful performance than common liquid leveling under some condition, especially in hydroxyalkyl and extinction system, it play excellent to the coating surface. It has a better cost-effective by the two ingredient’s synergistic effect.

Use active liquid leveling agent in plain flour, can arise the gloss; while in matting agent it help a lot to coating surface’s property, without enhancing gloss.