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Common Defects in UV Wood Coatings (Part 8)

Release time:

2026-03-16 17:14

Common Defects in UV Wood Coatings (Part 8)

In today’s wood coatings industry, UV wood coatings have secured a prominent market position thanks to their outstanding advantages—rapid curing, environmental friendliness, and energy efficiency—and are widely used for surface finishing of various types of furniture and wood products. However, in actual production and application, UV wood coatings do not always deliver flawless coating results; defects frequently occur, with poor curing leading to stickiness being particularly prevalent. Sticky film not only compromises the aesthetic appeal and tactile quality of the product, depriving it of the expected smoothness and neatness, but also severely undermines the protective performance of the coating, thereby reducing the product’s service life and market value. A thorough analysis of the phenomenon of stickiness caused by inadequate curing in UV wood coatings, along with its underlying causes, is of critical practical significance for addressing this challenge and enhancing coating quality.

I. Description of the Phenomenon

Even after thorough exposure to ultraviolet light, the paint film still exhibits a persistent tacky feel on its surface. A light touch with a finger reveals obvious stickiness, and fingerprints are readily left behind. A gentle scratch with a fingernail leaves a visible mark that does not spontaneously heal. When workpieces are stacked or packaged, the painted surface can adhere to contacting materials, and separation may result in damage to the paint film. Wiping with a cotton cloth can leave lint that adheres firmly to the surface and is difficult to remove. The tackiness may manifest as uniform adhesion across the entire paint film surface, or as localized areas of stickiness while other regions remain normal. In severe cases, the paint film surface resembles uncured adhesive; pressing with a finger can pull up fine filaments. Such tacky paint films exhibit significantly lower hardness than expected and lack the requisite protective performance.

II. In-depth Analysis of the Root Causes

1. Energy deficiency

(1) Light source degradation: As the UV lamp operates over time, the intensity of its emission spectrum gradually declines, particularly in the primary wavelength band. When the light intensity falls below the activation threshold required by the coating’s photoinitiators, the polymerization reaction remains incomplete.

(2) Insufficient light exposure: The conveyor belt speed is too high, resulting in an insufficient dwell time of the paint film under the UV lamps and inadequate total energy absorption. Alternatively, the lamps are mounted at an excessively high elevation, leading to a substantial reduction in the energy reaching the paint film surface.

2. Coating Barrier

(1) Excessive coating thickness: For pigment-based UV coatings or high-fill primers, excessive coating thickness limits the penetration depth of ultraviolet light. The top layer absorbs most of the UV radiation, preventing the photoinitiators in the underlying layers from receiving sufficient energy and resulting in incomplete curing of the substrate.

(2) Pigment absorption: Pigments such as carbon black and titanium dioxide strongly absorb or scatter ultraviolet radiation, creating a shielding effect that severely impedes UV penetration and results in insufficient deep-layer curing.

3. Chemical Inhibition of Polymerization

Oxygen influence: Oxygen in the air rapidly reacts with the free radicals generated by the photoinitiator, consuming these active radicals and preventing them from initiating monomer polymerization. As a result, the polymerization degree remains extremely low within an ultra-thin surface layer, leaving the material persistently tacky.

III. Conclusion

The issue of poor curing and stickiness in UV wood coatings arises from the complex interplay of multiple factors, including energy input, coating formulation, and chemical interactions. From the proper maintenance and timely replacement of UV lamps to the precise adjustment of conveyor belt speed and lamp mounting height; from strict control of film thickness to careful selection of pigments; and from effective oxygen exclusion in the production environment—every step is critical to achieving complete curing of the coating film. Only by comprehensively and thoroughly understanding these factors and implementing targeted, practical measures can the problem of inadequate curing and stickiness in UV wood coatings be effectively addressed, ensuring the production of high-quality, high-performance coatings that provide reliable protection and aesthetic appeal for wood products, thereby securing a competitive edge in the fiercely contested market.

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Boxing Recommended Products – UV Wood Coatings
Putty primer
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
Sanding primer
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-163	Modified epoxy acrylate	Good flexibility, excellent pigment wetting, and strong adhesion.
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
Apply primer
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-02	Phosphate ester acrylate	Enhances adhesion to substrates such as metal, glass, and plastic.
B-05	Phosphate ester acrylate	Enhances adhesion to substrates such as metal, glass, and plastic.
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-165	Modified epoxy acrylate	Good flexibility and strong adhesion
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
B-535	Polyester acrylate	Excellent adhesion, rapid curing, good flexibility, and yellowing resistance.
B-546	Polyester acrylate	Good adhesion, fast curing, and excellent flexibility.
White primer
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
B-529	Polyester acrylate	Good adhesion, low shrinkage, and excellent resin compatibility.
B-560	Polyester acrylate	Fast curing and excellent pigment wetting
Gloss topcoat
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-163	Modified epoxy acrylate	Good flexibility, excellent pigment wetting, and strong adhesion.
B-165	Modified epoxy acrylate	Good flexibility and strong adhesion
B-21C	Active amine photosensitizing promoter	Low color number, antioxidant and polymerization inhibitor, and enhanced curing rate
B-301	Aromatic Polyurethane Acrylate	Fast curing, good toughness, and excellent grindability.
B-302	Aromatic Polyurethane Acrylate	Fast curing, high strength, good toughness, and excellent grindability.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
B-601	Aromatic Polyurethane Acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost performance.
B-609	Aliphatic polyurethane acrylate	Fast curing, high hardness, scratch resistance, and chemical resistance.
B-868	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-868H	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-910A2	Aliphatic polyurethane acrylate	Low viscosity, yellowing resistance, chemical resistance, and steel-wool resistance.
B-912	Aliphatic polyurethane acrylate	Fast curing, high hardness, good toughness, and excellent chemical and wear resistance.
Matte topcoat
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-163	Modified epoxy acrylate	Good flexibility, excellent pigment wetting, and strong adhesion.
B-21C	Active amine photosensitizing promoter	Low color number, antioxidant and polymerization inhibitor, and enhanced curing rate
B-328M	Aliphatic polyurethane acrylate	Low gloss, low viscosity, excellent wettability, and a pleasant hand feel.
B-328R	Aliphatic polyurethane acrylate	Low gloss, excellent matting, good wetting, and a fine, smooth, and silky hand feel.
B-333	Aliphatic polyurethane acrylate	Low viscosity, excellent matting effect, good wettability, and good flexibility.
B-572	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
B-650A	Aliphatic polyurethane acrylate	Low viscosity, excellent matting effect, fast curing, and good wettability.
B-868	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-868H	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-910A2	Aliphatic polyurethane acrylate	Low viscosity, yellowing resistance, chemical resistance, and steel-wool resistance.
B-912	Aliphatic polyurethane acrylate	Fast curing, high hardness, good toughness, and excellent chemical and wear resistance.
Bright White Finish
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-301	Aromatic Polyurethane Acrylate	Fast curing, good toughness, and excellent grindability.
B-302	Aromatic Polyurethane Acrylate	Fast curing, high strength, good toughness, and excellent grindability.
B-560	Polyester acrylate	Fast curing and excellent pigment wetting
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
B-601	Aromatic Polyurethane Acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost performance.
B-868	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-868H	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-912	Aliphatic polyurethane acrylate	Fast curing, high hardness, good toughness, and excellent chemical and wear resistance.
Adherent
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-05	Phosphate ester acrylate	Enhances adhesion to substrates such as metal, glass, and plastic.
B-509B	Polyester acrylate	Good adhesion, good flexibility, and excellent pigment wetting.
B-531	Polyester acrylate	Good adhesion, impact resistance, excellent flexibility, and yellowing resistance.
B-535	Polyester acrylate	Excellent adhesion, rapid curing, good flexibility, and yellowing resistance.
B-546	Polyester acrylate	Good adhesion, fast curing, and excellent flexibility.
B-590	Polyester acrylate	Excellent adhesion, rapid curing, and good pigment wetting.
Filler type
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
B-529	Polyester acrylate	Good adhesion, low shrinkage, and excellent resin compatibility.
Color correction
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-560	Polyester acrylate	Fast curing and excellent pigment wetting
Harden
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-301	Aromatic Polyurethane Acrylate	Fast curing, good toughness, and excellent grindability.
B-302	Aromatic Polyurethane Acrylate	Fast curing, high strength, good toughness, and excellent grindability.
B-560	Polyester acrylate	Fast curing and excellent pigment wetting
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
B-601	Aromatic Polyurethane Acrylate	High hardness, scratch resistance, chemical resistance, and excellent cost performance.
B-912	Aliphatic polyurethane acrylate	Fast curing, high hardness, good toughness, and excellent chemical and wear resistance.
Matte
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-328M	Aliphatic polyurethane acrylate	Low gloss, low viscosity, excellent wettability, and a pleasant hand feel.
B-328R	Aliphatic polyurethane acrylate	Low gloss, excellent matting, good wetting, and a fine, smooth, and silky hand feel.
B-329D	Aliphatic polyurethane acrylate	Low irritation, low viscosity, excellent wettability, and a pleasant feel.
B-333	Aliphatic polyurethane acrylate	Low viscosity, excellent matting effect, good wettability, and good flexibility.
B-650A	Aliphatic polyurethane acrylate	Low viscosity, excellent matting effect, fast curing, and good wettability.
Solid-color paint
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-519	Self-curing polyester acrylate	Self-initiated photopolymerization performance
B-530	Polyester acrylate	Low viscosity, excellent hydrophobicity, thixotropy, and improved ink misting
B-560	Polyester acrylate	Fast curing and excellent pigment wetting
Yellowing resistance
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-431	Cycloaliphatic Specialty Acrylates	Yellowing resistance, excellent wettability, low viscosity, and fast curing
Dip coating
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
Roll coating
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-100	Bisphenol A epoxy acrylate	High hardness, high gloss, excellent chemical resistance, and high fullness.
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-160D	Modified epoxy acrylate	Good flexibility, yellowing resistance, and excellent adhesion.
B-163	Modified epoxy acrylate	Good flexibility, excellent pigment wetting, and strong adhesion.
B-165	Modified epoxy acrylate	Good flexibility and strong adhesion
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-522	Polyester acrylate	Low shrinkage, excellent flexibility, strong adhesion, and high cost-effectiveness.
Solvent-free spraying
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-251	Aromatic Polyurethane Acrylate	Fast curing, excellent flexibility, and good wetting of black ink pigments.
B-520	Polyester acrylate	Low viscosity, high gloss, excellent wettability, and cost-effective
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
LED-UV
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-21C	Active amine photosensitizing promoter	Low color number, antioxidant and polymerization inhibitor, and enhanced curing rate
B-241	Aliphatic polyurethane acrylate	Fast curing, excellent skin feel, and yellowing resistance.
B-27	Active amine photosensitizing promoter	Low color number, benzene-free, low odor, antioxidant and anti-polymerization
B-570	Polyester acrylate	Low viscosity, benzene-free, low odor, suitable for LED UV
B-574	Polyester acrylate	Benzene-free, low odor, and VOC levels meet cigarette pack standards.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
Excimer lamp
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-241	Aliphatic polyurethane acrylate	Fast curing, excellent skin feel, and yellowing resistance.
Skin feel
Product Model/English Abbreviation	Product Name/Product Type	Product Features
B-113	Bisphenol A epoxy acrylate	High hardness, high gloss, high fullness, contains 20% TPGDA
B-165	Modified epoxy acrylate	Good flexibility and strong adhesion
B-241	Aliphatic polyurethane acrylate	Fast curing, excellent skin feel, and yellowing resistance.
B-328M	Aliphatic polyurethane acrylate	Low gloss, low viscosity, excellent wettability, and a pleasant hand feel.
B-328R	Aliphatic polyurethane acrylate	Low gloss, excellent matting, good wetting, and a fine, smooth, and silky hand feel.
B-574C	Polyester acrylate	Low viscosity, low odor, excellent wettability, suitable for LED UV
B-868	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
B-868H	Organosilicon UV-Curable Resin	Excellent leveling, smooth finish, fast curing, and stain resistance.
Single-item recommendation
Product Model/English Abbreviation	Product Name/Product Type	Product Features
BM2223/TPGDA	Di(propylene glycol) diacrylate	Good flexibility and low volatility
BM2224/EO-HDDA	Ethoxylated 1,6-hexanediol diacrylate	Good adhesion to plastics, good dilutability, and low volatility.
BM3231/TMPTA	Trimethylolpropane triacrylate	High crosslink density, high hardness, high gloss, and excellent wear resistance.
BM3235/PET3A	Pentaerythritol triacrylate	Fast curing, high crosslink density, high hardness, and excellent chemical resistance.
BM3380/3EO-TMPTA	Tripropylene Glycol Triacrylate	More flexible and less irritating than TMPTA.
BM6261/DPHA-80	Dipentaerythritol hexaacrylate	High crosslink density, high hardness, chemical and wear resistance, and water resistance.
BM6263/DPHA-90	Dipentaerythritol hexaacrylate	High crosslink density, high hardness, chemical and wear resistance, and water resistance.

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Common Defects in UV Wood Coatings (9)

Common Defects in UV Wood Coatings (Part 7)