Accelerated weathering performance of Scots pine preimpregnated with copper‐based chemicals before varnish coating Part:1 coated with cellulosic and polyurethane varnishes

This study aimed to determine the effect of accelerated weathering on gloss, surface hardness and colour changes of Scots pine (Pinus sylvestris L.). Test samples were impregnated with Adolit KD‐5, Wolmanit CX‐8 and Celcure AC‐500 covered with cellulosic and polyurethane varnishes. The results showed that the values of surface hardness and gloss increased after accelerated weathering. While the surface hardness of Scots pine was increased for impregnated and polyurethane‐coated varnish, it decreased for impregnated and cellulosic varnish‐coated Scots pine after 1000 hours of accelerated weathering exposure. Copper‐based chemical impregnation and varnish coating developed the gloss of Scots pine specimens relative to the surface characteristics observed in single‐coated Scots pine specimens. While the most appropriate chemical was Celcure AC‐500 for surface hardness, it was Adolit KD‐5 for the gloss of Scots pine after 1000 hours of accelerated weathering exposure. Wood specimens impregnated prior to the application of varnish were more effective in stabilising the colour of Scots pine than Scots pine only coated with varnish. Polyurethane varnish‐treated Scots pine showed better colour stability for each partial and total accelerated weathering exposure period. The total colour changes were lowest for polyurethane varnish‐coated Scots pine impregnated with Celcure AC‐500 after 1000 hours of accelerated weathering exposure.     

Effects of adding TiO<Subscript>2</Subscript> nanoparticles to a water-based varnish for wood applied to nine tropical woods of Costa Rica exposed to natural and accelerated weathering

The addition of titanium dioxide nanoparticles (TiO₂ nanoparticles) to a water-based varnish used for finishing tropical woods was studied. Three different concentrations of TiO₂ nanoparticles (0%, 1.0%, and 1.5%) were evaluated. The nanoparticles were characterized by means of the transmission electron microscopy and an X-ray diffractometer. The varnish prepared was evaluated for its viscosity, adhesion of the film to the wood, water absorption, and the effects of natural weathering on the color and quality of the varnish. It was found that viscosity decreases as the concentration of TiO₂ nanoparticles increases, while no variation was found in the thickness of the film. Except for Gmelina arborea and Tectona grandis, the adhesion was not statistically affected. It was found that, in the 9 species tested, incorporation of TiO₂ nanoparticles decreased the values of water absorption. The evaluation of natural weathering showed that the varnish with no added TiO₂ nanoparticles degraded completely after 1 year of weathering exposure, while the modified varnish film endured. Less color change was observed in lumber treated with the varnish containing TiO₂ nanoparticles. The best performance of the varnish in the nine tropical woods used was observed when TiO₂ nanoparticles were added at 1.5% concentration.     

Correlation and modeling between color variation and quality of the surface between accelerated and natural tropical weathering in Acacia mangium,Cedrela odorata and Tectona grandis wood with two coating

To prevent the photodegradation process, a wide range of coatings have been developed. This study evaluated wood color change (ΔE*) and the surface quality index (SQI) generated by ASTM D‐660 standards in wood protected with polyurethane and varnish finishes of three tropical species (Acacia mangium, Cedrela odorata and Tectona grandis) in two weathering conditions (natural and accelerated condition). In addition, a model was developed to predict ΔE* and SQI in natural weathering based on ΔE* and SQI from accelerated weathering. The results showed that the application of these finishes generated variations in the color parameters of wood before being exposed to the elements. Additionally, it was found that finishes generated increases in ΔE*, especially the varnish type finish, and decreasing of SQI. Finally, models were found to predict color changes or surface quality in natural weathering based on color changes or surface quality in accelerated weathering. The model algorithm was expressed by ΔE* or SQI measured (X) and time exposure (t) in accelerated weathering by equation . With these models, it is possible to predict the equivalence of exposure times in natural weathering in tropical conditions for different kinds of finishes in three tropical species. © 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 519–529, 2014     

Surface properties of tannin-impregnated and varnished beech wood after exposure to accelerated weathering

The aim of this study was to determine selected surface properties of varnished beech wood impregnated with natural extracts after exposure to accelerated weathering. Beech wood samples were impregnated with aqueous solutions of 5 and 10% mimosa (Acacia mollissima) and quebracho (Shinopsis lorentzii) tannins. After weathering, colour changes (ΔL*, Δa*, Δb*, and ΔE*) in addition to scratch resistance and surface hardness values were calculated and evaluated. As a result of the weathering process, greater colour changes (ΔE*) were detected in the beech wood samples impregnated with tannins compared with the unimpregnated control samples. The least colour change occurred in the Tanalith-E-impregnated samples. Total colour change was adversely affected with tannin impregnation after the weathering processes. In terms of surface hardness and scratch resistance, the highest values were observed in the mimosa-solution-impregnated and control samples. Furthermore, it was found that scratch resistance and hardness values tended to increase during the first period of weathering and decreased thereafter. Regarding surface properties, the best results were obtained when polyurethane varnish was employed compared with the other varnish types.     

The effects of tannins on adhesion strength and surface roughness of varnished wood after accelerated weathering

This study evaluated the effect of accelerated weathering on the adhesion strength and surface roughness of beech wood (Fagus orientalis) treated with mimosa and quebracho extracts and coated with polyurethane, water-based, and cellulosic varnishes. Untreated beech wood blocks and beech wood blocks treated with Tanalith-E were used as control samples. Test samples were exposed to accelerated weathering processes of 100 and 300 h. According to the test results, the mean adhesion strength of the wood samples impregnated with mimosa and quebracho tannins decreased by a maximum of 20%, while increases in the mean surface roughness (R _a) were detected. The highest adhesion strength and lowest mean surface roughness were obtained with polyurethane varnish. Moreover, the mean adhesion strength increased with the accelerated weathering up to 100 h and then decreased thereafter. As a result of the weathering process, the mean surface roughness increased and was thus negatively affected.     

Effect of grey component replacement processing and varnishing on the light fastness of colours on cardboard prints

The visual appearance of packaging is one of its most important features. Electromagnetic irradiation causes a change in colour and often leads to colour fading (ie, to diminished visual appearance of a printed product). This research study aimed to determine the combined effect of grey component replacement image processing and varnishing on the protection of prints' appearance when exposed to accelerated ageing. For that purpose, two test charts were printed in a lithographic press and coated with water-based and ultraviolet-curable varnish before exposing them to xenon light. The prepared prints were evaluated by determining the tone values and colour difference, as well as the rub and abrasion resistance. In addition, Fourier Transform–infrared-attenuated total reflectance spectra were recorded to detect possible chemical changes caused by the (AcA). The results showed that the investigated period of (AcA) caused significant differences in the tone values of yellow, while the other primary colours proved to be more resistant. The water-based varnish provided better protection than the ultraviolet-curable varnish. The grey component replacement image processing diminished the colour difference caused by (AcA) on all the prepared print samples, and was particularly detected in tertiary colours containing the mid-range tone values of yellow (34%-68%). Both varnishes improved the rub resistance of aged prints, but only ultraviolet-curable varnish improved the abrasion resistance of both the unaged and the aged prints. In conclusion, applying varnish to prints ensured enhanced rub and abrasion resistance and diminished the colour change caused by (AcA). Finally, improved resistance to colour change was achieved by processing images with the grey component replacement method.     

Surface properties of impregnated and varnished Scots pine wood after accelerated weathering

In this study, the effect of accelerated weathering on the surface properties of Scots pine specimens impregnated with wolmanit‐CB, tanalith‐E, and adolit‐KD5 and coated with synthetic and polyurethane varnishes was investigated by measuring surface hardness, glossiness, and colour. Results showed that weathering caused an increase in the hardness of impregnated and varnished specimens, while it caused a decrease in the glossiness of specimens. Surfaces became rougher and darker after weathering in comparison with the initial surfaces of wood specimens. Positive values of the chromatic coordinates indicated that the wood surfaces changed from their original colour to a reddish and yellowish colour. The highest colour change was detected in the specimens coated with polyurethane varnish alone. Both copper‐based wood preservative treatment and varnish coating improved the surface properties of specimens in comparison with the surface properties observed on specimens coated with varnish alone.     

Influence of weathering on adhesion strength of chemically treated and coated Scotch pine

The objective of this study was to evaluate the effect of weathering on adhesion strength of Scotch pine (Pinus sylvestris L.) samples treated with three concentrations of Tanalith-E. Treated samples were also coated with polyurethane, synthetic and water based varnishes prior to 500 h accelerated weathering test. Adhesion strength between varnishing materials and substrate samples was determined employing pull-off type equipment. Based on the findings in this work adhesion strength values of samples decreased with increasing concentration of treatment chemical. The highest average strength value was found as 3.48 MPa for untreated control samples while 2.88 MPa was the lowest average value for the samples treated with Tanalith-E having 9% concentration and coated with water based varnish. Majority of the failures took place within the adhesion line between coating and the substrate with a very limited torn fibers. Results of statistical analysis revealed that samples coated with three different types of varnishes did not show any significant difference from each other at 95% confidence level. It was also found that chemical treatment of the samples adversely influenced their overall adhesion strength characteristics.     

Thermal conductivity of oriental beech impregnated with fire retardant

This study aims to describe the effects of wood material (oriental beech) impregnated with ammonium sulfate, borax, boric acid, and zinc chloride by using two different methods (pressure and dipping) and finishes with the effects of different varnishes (polyurethane, cellulosic, synthetic) and paints (cellulosic, synthetic, industrial) on thermal conductivity. These materials were used as fire retardants. The lowest thermal conductivity of 0.143 kcal/m h°C was obtained in oriental beech control samples. The highest thermal conductivity of 0.172 kcal/m h°C was obtained in oriental beech impregnated with ammonium sulfate by using pressure and varnished with synthetic varnish. Consequently, wood impregnated with ammonium sulfate by using pressure and finished with synthetic varnish can be used as a construction material where thermal conductivity is required. Wood impregnated with borax by dipping and finished with cellulosic varnish can be used as a construction material where the insulation is required.     

紫外可见光谱法在材料耐老化性能检测中的应用

考察了树脂清漆的紫外吸收及加速老化情况,发现两种测试方法之间有很好的相关性,把紫外光谱法用于涂料产品配方的优选可以缩短试验周期,加快产品的开发速度。     

FTIR studies of the effects of outdoor exposure on varnish-coated wood pretreated with CCB or water repellents

Scots pine (Pinus sylvestris L.)and chestnut (Castanea sativa Mill.) panels were coated with a polyurethane or an alkyd-based synthetic varnish. Some of the panels were impregnated with chromium-copper-boron (CCB) or the varnishes themselves before coating, as preservative-coating or water repellent (WR)-coating combination treatments, respectively. Earlier drastic changes in the intensity of the bands assigned to lignin and their shifts to some other stretching points were mostly attributed to chemical modification of lignin with the chromium in CCB, as well as the previously reported high color stability of CCB-impregnated wood. IR spectra of the nine months of weathering indicated that the synthetic varnish coating of non-impregnated or CCB-impregnated wood limited the reactions in lignin compared with polyurethane coating. Wood density and structural difference also seemed to play an important role since changes in lignin were mostly observed after six months of exposure for chestnut wood. Therefore, chemical reactions of CCB-wood cell wall components on the surface appeared likely to be affected from varnish type (their relative absorbency and distribution of sunlight), wood species (density and extractive substances), and exposure time and conditions. Technical Education Faculty, Mugla, 48000 Turkey. Faculty of Forestry, Trabzon, 61080 Turkey.     

Effect of grafted UV stabilizers on wood surface erosion and clear coating performance

The critical element for a durable exterior clear coating on wood is photochemical stability of the wood surface beneath the coating. If this interface is not stabilized, even a durable coating will delaminate due to photoinduced wood degradation. A new method for stabilizing the wood surface was developed and evaluated. HEBP [2-hydroxy-4-(2,3-epoxypropoxy)benzophenone] was grafted to western redcedar (Thuja plicata). HEBP contains an ultraviolet (UV) stabilizer moiety that improved the xenon are accelerated weathering performance of western redcedar (WRC). The weathering performance of the HEBP-modified WRC was compared with WRC treated with an unbound UV stabilizer of similar type and with untreated controls. The grafted stabilizer reduced the erosion rate (weathering) of unfinished WRC, and, as a pretreatment under clear finishes (spar varnish and exterior grade polyurethane), the stabilized surfaces improved coating performance and color retention.     

UPVC门窗型材用复合稳定剂的对比研究

选择未增塑聚氯乙烯（UPVC）门窗型材市场上常用的铅盐复合稳定剂、稀土复合稳定剂和新近推出的钙锌复合稳定剂，在配方相同或相近的条件下，采用刚果红试验、吉尔加速热老化试验、转矩流变试验、耐候性试验比较加入不同复合稳定剂的未增塑聚氯乙烯材料的热稳定性、流变性和耐候性，反推其对应复合稳定剂的热稳定剂、内外润滑匹配和光稳定剂的差异。结果显示：传统的铅盐类复合稳定剂在UPVC材料的热稳定性上占优势，新推出的钙锌类复合稳定剂在UPVC材料的耐候性上占优势，而不同复合稳定剂的内外润滑匹配的差异性导致UPVC材料的流变行为不一致。     

水性汽车罩光清漆的制备

研究了汽车通用水性罩光清漆的生产工艺,通过试验确定了最佳工艺条件:润湿剂用量为0.5%;消泡剂用量为0.5%;增稠剂用量为0.4%;水性多功能助剂用量为0.5%。通过对生产工艺条件的研究,使汽车水性罩光清漆的施工适应性大大提高,为水性罩光清漆大面积推广奠定了坚实的基础。     

石油管材用外防腐清漆的研制

以甲基丙烯酸甲酯、甲基丙烯酸为原料与醇酸树脂作用制备石油管材外防腐清漆,讨论了单体共聚的配比,植物油的选择,催干剂的选择,助剂的选择等对防腐清漆性能的影响。制得的清漆综合性能良好,耐冲击,在石油管材下油井之前的运输、贮存过程中起到有效的保护、防腐蚀的作用。     

Synthesis and Characterization of Solventless Polyester Varnish Based on Di Cyclo Penta Diene (DCPD)

Solventless polyester varnish was synthesized by polyesterification reaction of fumaric acid (FA), propylene glycol (PG) and dicyclo penta diene (DCPD) using triphenyl phenol (TPP) as accelerator. The resulting material was characterized by FT-IR and NMR spectroscopy. The electrical properties of varnish were also measured; volume resistivity was found 5.22 × 10¹⁷ Ohm-cm at room temperature, which fulfills main requirement of electrical insulating material. Solventless polyester varnish was crosslinked with styrene, vinyl toluene, and blend of both monomers, respectively in different ratios. Tensile strength of different type of the cured varnish with vinyl monomers was also determined, which was very high for vinyl toluene cured varnish. Thermal stability of the cured samples was determined by Thermogravimetric analyzer (TGA).     

不同条件下尼龙材料光老化行为的研究

目前,氙灯加速老化试验是评估材料耐候效果最常用的一种方法.但是,关于该测试方法是否能客观反应材料实际使用过程中的颜色、力学变化规律的相关数据积累非常少.详细对比了两种测试条件对材料耐候效果的影响,结果表明,在定性评估方面,不同耐候剂组合在两种老化试验中的优劣顺序基本上保持一致,说明氙灯加速老化试验可以比较客观地反映材料...     

ABS材料人工加速老化与户外自然老化的相关性

通过红外光谱、色差和力学性能等研究了丙烯腈–丁二烯–苯乙烯塑料(ABS)在人工加速老化试验(UVA,UVB和氙灯)及户外自然老化试验过程中老化行为的相关性。红外分析结果表明,不同ABS材料在人工加速老化和自然老化过程中遵循相同的光氧老化动力学,但不同光源对ABS材料的加速老化作用有明显差别;色差分析结果表明,人工加速老化试验对色差变化的加速倍率由大到小顺序为:UVBUVA氙灯。通过分析ABS材料的色差及力学性能在人工加速老化与户外自然老化过程中变化的相关性,拟合了人工加速老化与户外自然老化的时间换算方程。     

The effects of surface roughness on varnish adhesion strength of wood materials

In this study, the effects of surface roughness of wood material on the adhesion strength of varnish layers have been tested. For this purpose, test samples of beech (Fagus orientalis L.), Scots pine (Pinus sylvestris L.), and cherry (Prunus cerasus) wood species were prepared and sanded with 80, 120, and 180 grit abrasives. The surface roughness values of specimens were determined using a stylus-type profilometer TIME TR 200 according to the ISO 4287 standards. Then, water-based, polyurethane, and acrylic varnish were applied to the surfaces of the samples in accordance with ASTM-D 3023. Layer adhesion strength was determined to the TS EN ISO 4624 standards. As a result, the highest adhesion strength value (2.52 N/mm²) was found in cherry, while the Scots pine had the lowest value (2.32 N/mm²). For the varnish types, polyurethane varnish types gave the highest value (3.15 N/mm²), while the lowest value was obtained from the water-based varnish. Looking at interactions between adhesion strength and surface roughness, the water-based varnish had the strongest correlation with adhesion strength (69%) and acrylic varnish also had a similar result (67%), while polyurethane varnish had the weakest result (33%) in this interaction.