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Article
Publication date: 1 May 2019

Bo Wang, Yanhua Zhang, Haiyan Tan and Jiyou Gu

The purpose of the study was to prepare melamine-urea-formaldehyde (MUF) resin that would be resistant to boiling water and high temperature and exhibit low formaldehyde emission.

Abstract

Purpose

The purpose of the study was to prepare melamine-urea-formaldehyde (MUF) resin that would be resistant to boiling water and high temperature and exhibit low formaldehyde emission.

Design/methodology/approach

The authors prepared MUF resin with different F/(M + U) and changed the amount of melamine added, through the analysis of MUF resin properties to get the best reaction parameters, and used different amino acid cure systems including NH4Cl cured the resin.

Findings

Resin’s heat resistance and water resistance are mainly determined by the amount of melamine added, and formaldehyde emission of the plywood can be changed by adjusting F/(M + U). The peak temperature of the curing agent-cured resin increases as compared with the self-curing resin. Stronger the acidity of curing agent, faster the viscosity increased in probation period and lower the bonding strength and heat resistance of the resin.

Research limitations/implications

Melamine improves the heat resistance and water resistance of the resin. When the amount of melamine is more than a certain value, water resistance of the resin decreased.

Practical implications

MUF resin that is resistant to boiling water and exhibits low formaldehyde emission can be used in high temperature, high humidity and strict formaldehyde emission environment and can also be combined with other materials.

Social implications

It was helpful to reduce the effect of formaldehyde emission on people’s health and environmental pollution and is also beneficial for the expansion of the application range of aldehyde resin.

Originality/value

The originality is twofold: the influence of the acid strength of curing agent on the bonding strength of the resin adhesive and the method for preparing high performance MUF resin by following the traditional process.

Details

Pigment & Resin Technology, vol. 48 no. 3
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 30 August 2013

Esin Ateş, Nurseli Uyanık and Nilgün Kızılcan

The purpose of the research was as follows. In situ modified urea formaldehyde resins were prepared from clay (montmorillonite) and organoclay in the presence of base…

Abstract

Purpose

The purpose of the research was as follows. In situ modified urea formaldehyde resins were prepared from clay (montmorillonite) and organoclay in the presence of base catalyst. Different clay contents (1 wt%, 3 wt%, 6 wt%) were used to produce clay modified nanocomposite resins. These nanocomposites were characterized with FT‐IR, XRD as structural analysis and DSC as thermal analysis and their hardness was evaluated as mechanical analysis. The thermal results was compatible with hardness measurements and showed that using clay/organoclay added resin as a surface coating material provides significant improvement.

Design/methodology/approach

During synthesis of the resin, modification was carried out using urea/formaldehyde with molar ratio of 1/1.6, under basic medium with pH=10 and with temperature of 70°C by loading pristine and organomodified layered silicates.

Findings

X‐ray diffraction (XRD) results indicate that the interlayer space of pristine clay was increased significantly by one step, seeing that one step processes are crucial for industrial applications.

Research limitations/implications

The reaction mixture must be stirred continuously. Temperature should be controlled in order to prevent the thermal curing of urea formaldehyde resin.

Practical implications

This study provides technical information for the synthesis of nanocomposite resins. The clay or organoclay modified resins may also promote the adhesive strength of coating and also inhibit corrosion effects to metal surfaces of the coated area.

Social implications

This resin will be used for the coating material.

Originality/value

As Tg‐Tm region of some nanocomposites is enhanced, and by assessing the results of hardness measurements, it is concluded that these samples have further improved mechanical properties as a coating material than urea formaldehyde resin has.

Details

Pigment & Resin Technology, vol. 42 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 February 2002

P. Kalenda and A. Kalendová

The paper deals with the mode of film formation from ureaformaldehyde and melamine–formaldehyde resins combined with alkyd resin based on castor oil‐modified alkyd. The…

Abstract

The paper deals with the mode of film formation from ureaformaldehyde and melamine–formaldehyde resins combined with alkyd resin based on castor oil‐modified alkyd. The properties of hardened coatings (such as hardness, chemical stability, and adhesion to substrate) were followed in dependence on the ratios of reaction components. An apparatus was built for measuring the formaldehyde emissions escaping from the solid coating films. The determination was performed by the pararosaniline method. The addition of imidazolidine in a concentration up to 10 per cent can reduce the emissions of formaldehyde escaping from the solid films to a considerable amount.

Details

Pigment & Resin Technology, vol. 31 no. 1
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 30 August 2013

Hassan Salah Aly Emira, Yosreya Mostafa Abu‐Ayana and Sanaa Mohammad El‐Sawy

The purpose of this paper is to study the corrosion protective properties of modified urea and/or thiourea formaldehyde resins for steel surface.

Abstract

Purpose

The purpose of this paper is to study the corrosion protective properties of modified urea and/or thiourea formaldehyde resins for steel surface.

Design/methodology/approach

Three butyl alcohol modified amino resins were laboratory prepared. The three modified resins were characterized using thermal gravimetric analysis and infrared; the solid content and refractive index of each were also measured.

Findings

The resins that contain both nitrogen and sulphur have excellent corrosion inhibitive activity compared with that containing nitrogen only.

Research limitations/implications

The modified resins were based on urea formaldehyde resin, mixed urea and thiourea formaldehyde resin and thiourea formaldehyde resin, respectively.

Practical implications

The prepared resins were introduced in different coating formulations based on short‐oil alkyd resin, medium‐oil alkyd resin and plasticized chlorinated rubber. They were then tested and evaluated for corrosion protection of steel surfaces.

Originality/value

All the prepared resins show promising results for corrosion protection of steel surfaces.

Details

Pigment & Resin Technology, vol. 42 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

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Article
Publication date: 1 May 1978

R.A. Ellis

The interaction between formaldehyde and urea or thiourea has been reported by Richard and Gourdenne who used G.P.C. columns packed with reticular polystyrene gel of pore…

Abstract

The interaction between formaldehyde and urea or thiourea has been reported by Richard and Gourdenne who used G.P.C. columns packed with reticular polystyrene gel of pore sizes 3×104, 3×103, 103, 500, 200, 100, 60 and 60 A and which were eluted with N, N‐dimethylformamide at 50°C. These authors prepared precursors such as monomethylolurea and N, N‐dimethylolurea in aqueous base at 4°C which prevented their autocondensation. These materials were positively identified by proton nuclear magnetic resonance spectroscopy, but they were not resolved from one another nor from urea itself on the G.P.C. columns on account of the fact that the strong solvation by the eluent dimethyl‐formamide was not affected by the substitution of one or two methylol groups into the urea molecule. Using an acid solution at room temperature, it was found that the reaction between formaldehyde and urea or disubstituted urea produced substances such as methylene diurea and methylene di (N, N‐dimethylurea) which, respectively, eluted before and after urea itself. When urea or thiourea was reacted with formaldehyde at a molar ratio of 1:1.8 in a 30% aqueous solution of pH 8 at 95°C, it was shown by nuclear magnetic resonance spectroscopy that the individual urea residues were linked by ether bridges only and that methylenic linkages were totally absent. The degree of cross‐linking of the products was expressed in terms of the ratio of the number of protons included in these bridges to the total number of protons in the various methylene groups as determined by nuclear magnetic resonance spectroscopy. Five samples were taken from such a reaction between urea and formaldehyde. Their G.P.C. curves were obtained and they were shown to display a wider molecular size distribution as the calculated degree of cross‐linking increased. The initial sample was found to be comprised of a mixture of mono‐ and dimethylolurea, but the samples taken later on during the reaction were more highly polymerised and could not be assigned individual molecular structures. A similar conclusion was reached using a mixture of thiourea and formaldehyde in the preparation of a resin.

Details

Pigment & Resin Technology, vol. 7 no. 5
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 January 1996

F.F. Abd El Mohsen, R.M. Mohsen and Y.M. Abu Ayana

Modern glues are manufactured with high moisture and water resistance; ureaformaldehyde resins for gluing purposes are based on the fact that excellent control of the…

Abstract

Modern glues are manufactured with high moisture and water resistance; ureaformaldehyde resins for gluing purposes are based on the fact that excellent control of the condensation reaction is possible by variation of pH, which can be applied easily at the production process. Among conclusions is that the shear stress of these resins is twice that of the unmodified type.

Details

Pigment & Resin Technology, vol. 25 no. 1
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 April 1984

P.V.L. Barret

Formaldehyde and UF foam cavity wall insulation Urea formaldehyde (UF) foam cavity wall insulation was introduced into this country, from Denmark, in 1959. Relatively…

Abstract

Formaldehyde and UF foam cavity wall insulation Urea formaldehyde (UF) foam cavity wall insulation was introduced into this country, from Denmark, in 1959. Relatively little was installed until after the oil crisis which followed the Arab‐Israeli War of 1973. In total, some 1.5 million buildings have been insulated with it. UF foam is the cheapest material for retrofit cavity wall insulation. (All well‐installed systems have a comparable heat resistance.)

Details

Structural Survey, vol. 2 no. 4
Type: Research Article
ISSN: 0263-080X

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Article
Publication date: 1 February 2005

A.H. Basta, H. El‐Saied, R.H. Gobran and M.Z. Sultan

To investigate a new approach for the prevention of lignocellulosic composites based on agro‐fibres (e.g. sugar‐cane bagasse) from the emission of toxic formaldehyde.

Abstract

Purpose

To investigate a new approach for the prevention of lignocellulosic composites based on agro‐fibres (e.g. sugar‐cane bagasse) from the emission of toxic formaldehyde.

Design/methodology/approach

Five organic polymer containing nitrogen‐urea formaldehyde (UF) adhesive systems were used as bonding agents for bagasse fibres. The environmental performance of the lignocellulosic composites prepared were evaluated in terms of the effect of the organic polymers on the percentage of free formaldehyde in the adhesive system and the adhesion properties (static bending and water resistance properties) of the composite produced, in comparison with that prepared from un‐modified UF. The nitrogen content of the polymer and the amount of organic polymers incorporated in the adhesive system were optimised using the 3D response surface methodology and the multi‐linear regression technique.

Findings

All investigated organic polymers (crude PAM‐g‐starch, PAM‐g‐starch, PAM, CE‐starch and Cm‐starch) were found to enhance the performance of the UF‐adhesive for producing environmentally friendly bagasse‐composite, whereas the reduction of free‐HCHO in UF‐adhesive systems ranges from 26 to 100 percent. The performance of the composite produced exceeded the ANSI requirements for Grade H‐3 particle‐board.

Research limitations/implications

Despite the success in improving the performance (mechanical properties and reduction of free‐formaldehyde) of the UF‐adhesive and agro‐composites, the polymers needed to be incorporated at a high percentage (12‐20 percent) resulting in reduced water resistance of the product. Further investigation is needed to resolve this problem.

Practical implications

The approach developed provided a simple and practical solution to enhancing the performance of waste agro‐fibres and commercial amino adhesive in the production of high performance lignocellulosic composite.

Originality/value

The organic polymers UF adhesive systems are novel bonding agents for agro‐fibres and could be used in timber mills for production of particle‐board and medium density fibre‐board.

Details

Pigment & Resin Technology, vol. 34 no. 1
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 6 July 2010

F. Li, X.P. Li and W.H. Wang

The purpose of this paper is to investigate an adhesive prepared from soy flour (SF) modified with urea, citric acid and boric acid as an environmentally friendly product…

Abstract

Purpose

The purpose of this paper is to investigate an adhesive prepared from soy flour (SF) modified with urea, citric acid and boric acid as an environmentally friendly product for the wood industry.

Design/methodology/approach

Urea solution was prepared at 30°C and then SF was added and stirred at 30°C for 2 hours. Citric acid solution was added and stirred for another 0.5 hours and then boric acid solution was added and heated at 30°C for a further 0.5 hours. The resulting adhesive was used to bond poplar veneers. Shear strength was measured to evaluate the bonding property of the adhesive. Viscometry and FT‐IR spectrometry were used to test the viscosity and chemical changes, respectively.

Findings

Soy protein has potential value in the preparation of adhesives because of its unique functional characteristics. The optimum formulation was 100 g of soy powder treated with 9 g of citric acid at 30°C for 0.5 hours in the presence of sodium dihydrogen phosphate (NaH2PO4). After addition of 6 g of boric acid the resulting adhesive exhibited a shear strength of 0.82 MPa when bonded samples were treated with water, indicating that boric acid improved the water resistance via the formation of a chelating polymer.

Research limitations/implications

Compared to synthetic resin such as urea formaldehyde, the SF adhesive exhibited lower water resistance. Further modification methods and optimum chemical reagents still need to be investigated.

Originality/value

A new formulation for an environmentally friendly adhesive prepared from SF is identified for the panel industry. The bonding potential of soy protein was developed without any synthetic resin, which will promote industrial utilisation of an agricultural by‐product.

Details

Pigment & Resin Technology, vol. 39 no. 4
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 9 January 2009

Z. Gao, X‐M. Wang, H. Wan and Zhi‐Ming Liu

The purpose of this paper is to investigate the effects of various catalyst contents, resin solid contents, catalyst species and wood extract on ureaformaldehyde (UF…

Abstract

Purpose

The purpose of this paper is to investigate the effects of various catalyst contents, resin solid contents, catalyst species and wood extract on ureaformaldehyde (UF) curing by differential scanning calorimetry (DSC) technique. The finding obtained would benefit the manufacturers of UF‐bonded composite panels.

Design/methodology/approach

The UF curing rate under each condition in terms of DSC peak temperature was measured by high‐pressure DSC at a heating rate of 15°C/min; the correlations of peak temperature with catalyst content, resin solid content, catalyst species and wood extract, respectively, were regressed via a model equation, which described the curing characteristics of the UF bonding system.

Findings

A model equation, Tp=A · EXP(−B · CC per cent)+D, was proposed to characterise the DSC peak temperatures or the rate of UF curing with regressing coefficients greater than 0.97 (commonly greater than 0.99). The constants A and B in the model equation were found to correspond to kinetic characteristics of UF resin curing reaction. The constant D in the model equation is believed to be associated with the utmost peak temperature, which implies that the DSC peak temperature will finally reach a maximum with catalyst content increasing. It was also found that the wood extracts having higher pH value and base buffer capacity had stronger catalyses on UF curing.

Research limitations/implications

The catalysts commonly used in medium density fibreboard plants or particleboard plants are those having the utmost peak temperature of about 90‐95°C; the catalyses of wood extracts were much weaker than that of catalyst NH4Cl.

Practical implications

The model equation could be used to predict the peak temperature or the curing rate of UF resin, and to quantify the effects of wood extracts on UF curing.

Originality/value

The study developed a model equation that can well characterise the UF curing, and quantified the effects of wood extracts on UF curing.

Details

Pigment & Resin Technology, vol. 38 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

1 – 10 of 283