The influence of high wear-resistant UV matte coating matting powder!

Foreword: The mechanism of curing liquid coating materials using UV or EB energy radiation is now well known

Surface and mechanical properties of the resin, initiator careful selection and combination of control agents, fillers and additives, and viscosity must also be considered substrate adhesion and uv curable formulations, depending on the end use, industrial coatings may need to improve the performance characteristics of a plurality of coating Online coatingol.

However, the formulation of industrial coatings requires trade-offs, and the wear resistance of the formulation can be controlled by adding some fillers, which usually increases the viscosity of the formulation

Abrasion resistance and scratch resistance are key to many coating applications, but improving one of the parameters may reduce the other

Adding ultra-fine polyamide powder seems to be a simple method to achieve a balance of properties, obtain some or all of the mechanical properties and surface properties, while maintaining good substrate adhesion and low viscosity formulations

This article describes the behavior of ultrafine polyamide powder, ultrafine copolyamide powder and silica additives in the preparation of UV curing systems

The viscosity, light curing modification, gloss control, friction properties of the coating, dispersion of additives in the coating, and abrasion resistance of the UV curing formula were studied

1.

The basic polyurethane acrylate formulation (Table 1) consists of a mixture of acrylic monomers, such as isobornyl acrylate, 1,6 hexanediol diacrylate, dipentaerythritol pentaacrylate, and ethoxylated trimethylolpropane triacrylate.
Acrylate and urethane acrylic oligomer
.

This formulation is recommended for topcoats on rigid and flexible plastic substrates
.
Before adding ultra-fine polyamide powder, the key characteristics of the system are good adhesion to the plastic substrate and a good combination of hardness and flexibility
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Ultrafine polyamide powder is a polymer and copolymer formed by direct polymerization of laurolactam and/or caprolactam
.
This unique process produces microporous spherical beads with a specific size, specific surface area and melting point
.

The average particle size (APS) is 5 to 60 microns
.
The structure, shape, narrow particle size distribution and performance of these ultrafine polyamide powders make them significantly different from other powders or additives used in the coating industry
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The particle size distribution for each grade used in this study is very narrow, with an average particle size of 10 microns (Table 2 provides the typical physical properties of these polyamide grades and silica A)
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In this study, the concentration gradient of ultrafine polyamide powder and silica was used, from 1 part to 10 parts by weight of the total formula
.

2.
Application/curing

Apply the UV-curable formula to glass plates, flexible plastic substrates or BaF2 crystals with calibrated coating rods to obtain coatings with a thickness of 12, 24 or 35 μm
.

By operating the ultraviolet light at a speed of 5 m/min and exposing it to the radiation of a medium-pressure mercury lamp (IST-80 W/cm) for a short time (3 times), the maximum light intensity at the sample position is measured by the radiometric method (International Light IL390) measurement
.
All experiments were performed at room temperature
.

2.
1 The influence of polyamide powder during photopolymerization

By plotting 1-(A1/A0) as a function of exposure time (Figure 1), the conversion-time curve can be obtained from the initial (A0) and after the given exposure time (A1) the value of the infrared spectral absorbance
.

The real-time FTIR spectrometer (Bruker Optics IFS 66) was used to directly record the time-conversion curve of the ultra-fast reaction in the film.
This technology is very suitable for the kinetic analysis of the ultra-fast reaction in the film
.
In these experiments, the light intensity at the sample location was measured at 340mw/cm2
.

2.
2 Photopolymerization kinetics study on the influence of ultrafine polyamide powder

FT (RTIR) spectroscopy was used to study the effect of ultra-fine polyamide powder on UV curing formulations
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As shown in Figure 1, the conversion curve with time, the ultrafine polyamide powder (10% of the weight of the ultrafine polyamide 12 powder) has no effect on the photopolymerization kinetics
.

The same results were obtained for the ultrafine copolyamide powder 3501 EXD (10% by weight)
.

At 30 m/min (equivalent to 100 mJ/cm~2), it is proved that more than 75% of the acrylate double bonds in formula F0 can be polymerized under a UV lamp at a speed of 30 m/min (equivalent to 2 J).
/cm~2) The polymerization rate exceeds 98% after three passes (Figure 2)
.

3.
The influence of polyamide powder on the slip resistance of the coating

A very simple device shown in Figure 3 is used to evaluate the sliding properties of the coating surface
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Put 300g rubber sole (6x6 cm) on the UV curing film
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Then gradually tilt the sample until it starts to move downwards and measure the angle θ
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The greater the angle, the less smooth the surface
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The angle of formula F0 is about 30°
.
The addition of ultrafine polyamide 12 or copolyamide 6/12 powder reduces the angle to 25°
.
When the silica concentration is 10%, the angle drops to 18°
.
The performance of silica material is different from that of ultrafine polyamide powder
.

3.
Conclusion 

Ultrafine polyamide powder can be used to improve the performance of certain industrial coatings without affecting other properties or reducing the photopolymerization process
.

We found that with a lower addition amount, ultra-fine polyamide powder can improve the abrasion resistance of UV-curable industrial coatings, reduce gloss, and have the least impact on formulation viscosity and coating friction, while other additives have Layer friction has a negative effect
.

In the tested formulations, the abrasion resistance was increased by about 20%, and in some non-UV-curing systems, the abrasion resistance was even more improved
.

The formula composition, curing conditions or the density of the polyamide particles on the surface can explain this result
.
In the research of UV curing system, the introduction of ultrafine thermoplastic powder is the main reason to improve the wear resistance of the coating
.
All in all, ultrafine polyamide powder can improve the wear resistance and scratch resistance of these coatings while matting
.