Influence of VOC and formaldehyde emission from tile adhesives on their indoor concentrations in buildings

Volatile organic compounds (VOC) and formaldehyde emitted from building materials are considered to be one of the main causes of indoor air pollution in buildings. To reduce indoor pollutant concentrations, new installation methods for wall papers and flooring materials have been widely introduced to the construction field, including a nonadhesive floating method. However, adhesives are still widely used to install wall tiles or floor tiles on areas such as kitchens, bathrooms, and showers. The objective of this study was to investigate the influence of tile adhesive emissions on indoor air quality. The VOC and formaldehyde emission rates from two different types of tile adhesives, a conventional adhesive and a low-VOC emission adhesive, were measured using small emission test chambers. Full scale experiments were also carried out in three identical test rooms in a building. One wall of each room was finished with wallpaper in Test Room 1 and with tiles in Test Rooms 2 and 3. The other walls and ceilings were finished with wall papers in all test rooms. Wall tiles of Test Room 2 were installed with the conventional adhesive, while those of Test Room 3 were installed with the low-VOC emission adhesive. The indoor VOC concentrations in Test Room 2 were significantly higher than those in Test Room 3 due to a significantly higher VOC emission from the conventional tile adhesive. Even though the adhesives were applied under the finishing materials, investigation revealed that the adhesives were the most dominant contributor of indoor VOC concentration.     

Evaluation of VOC emission and sorption characteristics of low-VOC adhesive-bonded building materials

To reduce the risk of indoor air pollution caused by synthetic building materials, low-volitile organic compounds (VOC) building materials, including adhesives, are commonly used in building construction. Although adhesives do not directly contact indoor air, they affect VOC mass transfer at the surface of finishing materials by diffusion. This study investigates VOC emission and sorption behaviors of building materials with low-VOC adhesives. Small chamber emission and sorption experiments were designed in parallel to field measurements to examine the onsite VOC emission and sorption rates of adhesive-bonded building materials. It was found that the onsite emission rates from a wallpaper composite (polyvinyl chloride wallpaper?+?paper adhesive?+?gypsum board) were higher than the emission rates detected in the small-scale chamber, which demonstrates the possible sorption effect of the wallpaper composite. The results of the sorption chamber experiment confirm that the wallpaper is a sorptive building material and that the bonding of wallpaper to gypsum board increases the sorption and re-emission rates. These results indicate that even though low-VOC adhesive-bonded materials are used, additional indoor air quality control techniques should be applied to minimize re-emission by sorption processes over long periods of time.     

考虑地面积尘时置换通风的数值模拟

引言 置换通风系统始于北欧,较多应用于工业通风.近几年来,由于其合理的温度分布、较高的通风效率和明显的节能特性,置换通风系统已经越来越多地应用到民用建筑中.在北欧新建的办公建筑中,约有50%～70%的部分采用了置换通风系统[1].     

Using Renewables in Panelboard Resins to Influence Volatile Organic Compound Emissions from Panels

Technical lignin and condensed tannins have been combined with soy flour as model of no-added-formaldehyde adhesive binders for veneer wood products to understand their impacts on volatile organic compounds (VOCs) produced during panel manufacture. VOC emissions captured on manufacturing lauan hardwood plywood at 170?C were dominated by acetaldehyde, hexaldehyde, acetone, and terpenes in both the condensate and gaseous fractions of press emissions. Other aldehydes including formaldehyde, valeraldehyde, and propionaldehyde were produced in relatively lower quantity during panel manufacture. Compared to using soy flour alone, lignin, and tannin reduced the formaldehyde and acetaldehyde contents in press emissions. These reductions in VOCs had a dependency on adhesive resin pH with an alkaline formulation proving to also decrease longer chain aldehydes such as valeraldehyde and hexaldehyde. Chamber testing plywood panels found the composition of VOC emissions initially released from panels to be prominent compounds released in press emissions formed on panel manufacture. Use of soy flour alone as binder produced relatively high acetaldehyde emissions from panels, whereas incorporating lignin and tannin with soy flour as adhesive binders reduced both acetaldehyde and formaldehyde emissions from panelboards post-manufacture.     

NUMERICAL SIMULATION OF VOLATILE ORGANIC COMPOUNDS EVAPORATION IN CLOSED SPACES

This paper deals with the simulation of VOCs concentration dispersion, evaporated from flooring materials, with the purpose of understanding VOCs evaporation and dispersion mechanisms. A test chamber is examined whose flooring material emits a number of VOCs. Given the area specific ventilation rate and considering it as boundary conditions, experimental data for the examined compounds concentration, the dispersion of the VOCs concentrations is examined under steady state and transient conditions. The model developed is used in conjunction with a general - purpose CFD code, PHOENFCS, that can provide detailed information on the flow as well as concentration fields. The results of the above two simulation cases are used as a guide for two other cases, where faster restoration of the air indoor quality was investigated by changing the ventilation rate in the chamber. The simulation results were used as a basis for further analysis for VOC evaporation for other flooring materials; this will allow proper material selection as well as proper ventilation system for a more healthy and comfortable environment in a building.     

木焦油改性生物油-酚醛树脂胶粘剂的工艺条件研究

以木焦油作为BOPF(生物油-酚醛树脂)的改性剂,制备BTPF(木焦油改性生物油-酚醛树脂)胶粘剂,并用于胶合板的制备。以木焦油加入量、催化剂(NaOH)含量和反应时间作为试验因素,以胶接强度、黏度和凝胶时间作为评价指标,采用正交试验法优选出制备BTPF胶粘剂的最佳工艺条件。结果表明:当w(木焦油)=15%、w(NaOH)=4%和反应时间为40 min时,BTPF胶粘剂的综合性能相对最好,并且完全满足GB/T 14732-2006标准中的指标要求,相应胶合板的胶接强度(1.54 MPa)和甲醛释放量(0.25 mg/L)达到了GB/T 18580—2001标准中的Eo级指标要求。     

Comparison of Canola and Soy Flour with Added Isocyanate as Wood Adhesives

Canola is widely grown in the northern latitudes for its vegetable oil, generating large quantities of residual, low value canola flour used as animal feed. The common wood adhesive poly(diphenylmethylene diisocyanate) (pMDI) should react with the wide variety of functional groups in proteins. Therefore, it would seem that canola flour with added pMDI could be an effective adhesive. Two main questions are addressed in this study: How do the wood adhesive properties of canola flour compare to the better-studied soy flour? How well do proteins, which contain an abundance of functional groups, cure with the very reactive pMDI? These questions were addressed using the small-scale adhesive strength test ASTM D-7998, with various adhesive formulations and bonding conditions for canola flour plus pMDI compared to soy adhesives. The more challenging wet cohesive bond strength was emphasized because the dry strengths were usually very good. Generally, soy adhesives were better than canola ones, as was the polyamidoamine-epichlorohydrin cross-linker compared to pMDI, but these generalizations can be altered by the conditions selected. Three-ply plywood tests supported the small-scale test results.     

NUMERICAL SIMULATION OF VOLATILE ORGANIC COMPOUNDS EVAPORATION IN CLOSED SPACES

Abstract

This paper deals with the simulation of VOCs concentration dispersion, evaporated from flooring materials, with the purpose of understanding VOCs evaporation and dispersion mechanisms. A test chamber is examined whose flooring material emits a number of VOCs. Given the area specific ventilation rate and considering it as boundary conditions, experimental data for the examined compounds concentration, the dispersion of the VOCs concentrations is examined under steady state and transient conditions. The model developed is used in conjunction with a general - purpose CFD code, PHOENFCS, that can provide detailed information on the flow as well as concentration fields. The results of the above two simulation cases are used as a guide for two other cases, where faster restoration of the air indoor quality was investigated by changing the ventilation rate in the chamber. The simulation results were used as a basis for further analysis for VOC evaporation for other flooring materials; this will allow proper material selection as well as proper ventilation system for a more healthy and comfortable environment in a building.     

水相中合成木质素环氧树脂及其在木材胶黏剂中的应用

以木质素为原料,在水相中合成一种适用于木材胶黏剂的木质素环氧树脂。为了考察木质素环氧化反应条件对木质素环氧树脂的羟基和环氧基的影响,以及对胶合板的胶合强度的影响,采用FT-IR和31PNMR对木质素环氧树脂结构进行表征,并用TG和DTG对木质素环氧树脂的热稳定性进行分析。结果表明,环氧化反应主要发生在酚羟基上,在反应过程中,相比环氧氯丙烷,NaOH的加入量对木质素环氧树脂结构和胶合板的胶合强度影响更大。随NaOH加入量增加,木质素环氧树脂中环氧基团逐渐增多,胶合板的胶合强度呈现先升高、后降低的趋势。当木质素的羟基与NaOH摩尔比为1:1时,由木质素环氧树脂制得的胶合板胶合强度达到最大,湿强度达1.61 MPa,超过国家标准II类板的要求(≥0.7 MPa)。采用扫描电镜研究了黏接机理,发现环氧化程度提高时,固化后的木质素环氧树脂的结构更加稳定且致密,导致胶合板的胶合强度也提高。但过高的环氧化程度会增大胶黏剂的粒径,导致胶黏剂与木板不能形成更好的机械互锁结构,从而降低胶合板的胶合强度。还进一步简化了木质素环氧树脂木材胶黏剂的合成工艺,使环氧化反应后的体系无需处理即可直接应用于木材胶黏剂,减少了胶合板生产工艺流程。此外,经过30天的储存期,胶黏剂黏合强度没有明显下降。通过与商业脲醛树脂木材胶黏剂对比,其黏接强度可以达到商业脲醛树脂的水平。     

Head Space—Solid Phase Micro Extraction Profile of Volatile Organic Compounds Emitted from Parquet Samples

The potential health risks posed by volatile organic compounds (VOCs) in homes are of concern. There is little information on indoor VOC emissions from wood flooring, called parquet. Six parquet samples were examined for VOCs in this preliminary study using Head Space—Solid Phase Micro Extraction (SPME) gas chromatography, a powerful and versatile analytical method which has been only minimally employed previously in wood chemistry. Prefinished composite samples released the highest levels of VOCs, mainly due to adhesives and finishes, with acetic acid the main component released from the oak component. As some VOCs from parquet present a health hazard, more comprehensive studies employing the SPME technique described herein are needed.     

The Influence of FRW-1 Fire Retardant Treatment on the Bonding of Plywood

In this work the influence of FRW-1 fire retardant treatment on the bonding strength of plywood was studied. The results showed that the bonding strength of FRW-1 fire-retardant-treated Poplar plywood decreased by 25.3% as compared to untreated plywood; furthermore, free formaldehyde in the fire-retardant-treated Poplar plywood decreased by 64.9% when compared to untreated plywood. In our studies we also analyzed: the pH value and the buffering capacity of fire-retardant-treated and untreated wood powder; and the influence of FRW-1 fire retardant treatment on the gelation time of urea-formaldehyde (UF) adhesives. The results show that FRW-1 fire retardants reduced the pH value and increased the buffering capacity of FRW-1 fire-retardant-treated wood powder. The gelation time of the UF adhesive mixed with FRW-1 fire-retardanttreated wood powder was shortened by 15% as compared with the untreated wood powder. The results of the scanning electron microscope analysis showed that the FRW-1 fire retardant was mainly confined to: the trachea lumen of the Poplar wood; the wall of trachea; as well as around the pits when using an impregnation method at ambient temperature and pressure. It is possible that this has led to the decrease in mechanical action between the veneer and the adhesive.     

葛根淀粉基胶黏剂制备与性能研究

研究开发以淀粉为主要原料的环保型胶黏剂替代"三醛类"木材胶黏剂,对彻底解决人造板及其制品的甲醛释放问题具有重要意义。以野生葛根淀粉为原料,通过降黏处理,并与聚醋酸乙烯酯和异氰酸酯复配,制备出胶合强度达到国家Ⅱ类要求的淀粉基木材胶黏剂。研究了降黏剂用量、降黏时间、聚醋酸乙烯酯和异氰酸酯用量对淀粉基木材胶黏剂胶合强度的影响。优化工艺条件下制备胶黏剂胶接胶合板的胶合强度为1.89 MPa,能够满足国家Ⅱ类胶合板强度要求。     

Indoor air quality and the emissions of VOCs from interior products

Indoor air quality (IAQ) has developed into an important environmental and health concern. IAQ legislation has been introduced in the U.S. Congress. Volatile organic compounds (VOCs) comprise a part of the total concern about IAQ. Types and sources of pollutants contributing to IAQ are identified. Some strategies for reducing VOCs in indoor air are provided, and various sources of VOCs are identified. Various means of reducing VOC emissions from products are presented. Government regulatory agencies have begun to introduce legislation focusing on regulation of IAQ. Discussed is how these regulations, some proposed legislation, and customer concerns will affect both product manufacturers and their suppliers.     

A Soy Flour-Based Adhesive Reinforced by Low Addition of MUF Resin

The desire to prepare a lower-cost soy-based adhesive has led to an interest in using the abundant and inexpensive soy flour (SF) as a substitute for expensive soy protein isolates (SPI) in wood adhesives. However, the weakness of this adhesive is poor water-resistance and bonding strength due to a low protein content, which limits its application in the wood industry. The objective of this research was to provide a simple and useful approach for improving the adhesion performance of SF-based adhesive by introducing a small addition of melamine-urea-formaldehyde (MUF) resin into the cured system. The optimum addition level of MUF resin, as well as the adhesion performance and conformation change of SF-based adhesive, were investigated. The analytical results indicated that the co-condensed methylene bridges were formed through the reaction of methylol groups of MUF resin with soy units during the hot-press process. The addition of MUF resin, not only significantly decrease the viscosity of SF-based adhesive but also increase its water-resistance and wet shear strength value. The SF-based adhesive containing 20% MUF resin, is a relatively low-cost adhesive, has a reasonable viscosity, and moreover can pass the Chinese Industrial Standard requirement (0.7 MPa) for interior plywood panels.     

Decreasing the formaldehyde concentration in indoor air by improving the adhesives used in engineered wood materials in Korean apartment buildings

Engineered wood materials, such as the urea-formaldehyde resin adhesives used to make plywood, are known to be one of the primary sources of formaldehyde emissions in the building industry. This study presents the results of measuring indoor formaldehyde concentrations in newly built apartment buildings at the pre-occupancy stage for more than three years. Formaldehyde emissions from engineered wood materials used in floorings and furniture were measured using the small chamber method. Indoor formaldehyde concentrations were measured by following, for the most part, the procedure proposed by the Korean Ministry of Environment. These measurements verified that improving the engineered wood materials used in the apartment buildings had an effect on lowering the formaldehyde concentrations. The results showed apparent decrease in formaldehyde concentrations when low-emission engineered wood materials were used. Regardless of the absolute decrease, seasonal fluctuations in formaldehyde concentrations were also observed. It was assumed that these fluctuations were caused by changes in the indoor air temperature and relative humidity. Nevertheless, it will be necessary to conduct further studies to identify the factors causing the weak correlation of formaldehyde concentrations with the indoor air temperature and relative humidity in each housing unit.     

Plant Polyphenol-Inspired Crosslinking Strategy toward High Bonding Strength and Mildew Resistance for Soy Protein Adhesives

Soybean protein adhesives are environmentally friendly biomass-based aldehyde-free adhesives that have good economic value for the wood industry; however, it remains challenging to produce soybean protein adhesives with excellent water resistance, toughness, and mildew resistance through a simple modification method. In this work, inspired by plant polyphenols, a novel crosslinked soybean meal adhesive (SMPT) is obtained using a facile economic method. Polyamidoamine-epichlorohydrin (PAE) and tannic acid (TA) are combined with a soybean meal matrix to form a tough co-crosslinked network through strong intermolecular forces (covalent bonds, ionic bonds, and hydrogen bonds) in adhesive system. The results show that the wet bonding strength of SMPT adhesives for plywood is 134.1% higher than the unmodified soybean meal adhesive. The adhesion properties met the standard requirements for interior-use plywood. And the compact cross-linking network structure is accelerated the greater energy dissipation, which improves the toughness of adhesive. Moreover, cationic azetidinium groups in PAE and phenol hydroxyl groups in TA synergistically not only exhibit the good antibacterial activities but also improve mildew resistance for SMPT adhesives. This facile strategy provides an economic sustainable method to prepare high-performance environmentally friendly wood adhesives.     

杨木胶合板专用UF树脂胶的研究

速生杨木用于生产胶合板是近年内开始的，为解决杨木胶合板的胶合强度较低，油漆后发生鼓泡等质量问题，本文从木材的ｐＨ值、缓冲容量等方面着手，研究杨木的特性，并研制了适合杨木胶合板生产的专用ＵＦ树脂胶。     

冷等离子体处理单板对不同胶黏剂胶合强度的影响

冷等离子体预处理单板后,采用不同的胶黏剂热压制成胶合板,比较空白板和处理后的胶合板的胶合强度,并对N2等离子处理前后单板表面的化学组成进行了XPS分析。结果表明,经等离子处理后,尿胶的胶合板的调高幅度最大,最高达到了88.42%,对于同种胶黏剂,N2,O2,Ar,NH3的效果是N2NH3ArO2。XPS分析结果表明经N2冷等离子体处理后,木材表面的氧/碳原子浓度比增加,产生了大量含氧官能团或过氧化物,同时引入了N元素,推测有-NH2生成。     

A new source of natural adhesive: Acacia mangium bark extracts co-polymerized with phenol-formaldehyde (PF) for bonding Mempisang (Annonaceae spp.) veneers

Acacia mangium is a fast-growing dicotyledonous tree species and has become the dominating plantation in Malaysia. It was grown particularly as a raw material for veneer, pulp, and paper industries. The chemical properties test in this study showed that the A. mangium tree bark contains higher extractive content as compared to the wood portion (sapwood). Tannin extracts from A. mangium tree bark were found to be rich in phenolic compounds and had the potential to replace conventional phenol-formaldehyde (PF) adhesive used in the plywood manufacturing industry. Tannin adhesive (tannin-paraformaldehyde) prepared from A. mangium bark tannin by cross-linking with paraformaldehyde were used for bonding of Mempisang (Annonaceae spp.) plywood board. However, the resulting bonding strength using tannin adhesive was found to be only suitable for interior grade application. Further extension of its application for interior and exterior grade plywood could be achieved with addition of PF (co-polymerization with resol) during the production process. The optimized formulation of tannin adhesive consists of A. mangium solid extracts (90 parts), commercial PF (10 parts), and paraformaldehyde (3%). Results have shown that the plywood shear strength complies with the requirement for European norms EN 314-1 and EN 314-2:1993, which includes the dry test, cold water test, and the boiling test.     

木材用单组分湿固化聚氨酯胶粘剂的合成

以多亚甲基多苯基多异氰酸酯(PAPI)、聚丙二醇(PPG-N210)和催化剂2,2'-二吗啉二乙基醚(DMDEE)为主要原料合成了一种木材用单组分湿固化聚氨酯胶粘剂,分析了NCO含量、催化剂用量、扩链系数对胶粘剂性能的影响,并与国内外木材用胶粘剂进行了比较。结果表明,NCO质量分数为12.3%、催化剂用量为0.1%、扩链系数为0.2,制得的胶粘剂室温固化且固化速度快,粘接性能较好,适合于木材的粘接。