DEVELOPMENT OF RI~~-HllSk MODIFIEb UREA-FORMALbEHfDE ADHESIVE

8Y

DICKSON UDOBONG UDO 92/2112

DEI»AltME"Hr OF CHEMICAL EHalNEElUHG ~CHOOL of ENGINEEIUHG ANb ENGINttRtNGtEcHNblOGY

FEDEltAlUNIVEltSltv OF tECHNOLOGY MINNA, NIGER. StAtt.

A PROJECT REPORt s~BMltttb to THt btl'AlttHENt OF CHEMIcAL ENGINEERING, scHOOL O~ ENGINEERING

ANb ENGINEERING tECHNOLOGY, IN PARTIAL FULF.LMENT OF tHE REQUIREMENTS FOIt tHE AWARb

of THE DEGREE OF· BAcHELOR OF ENGINEERING (I.ENG) FEDERAL UNIVERSITf OF tECHNOLOGY, .

MaNNA; NIGER stAtE.

DECEMBElt, i 998.

,.

DEVELOPMENT OF RICE-HUSK MODIFIED , UREA-FORMALDEHYDE ADHESIVE

BY

DICKSON un6BONG uno 92/2712

DEPARTMENT OF CHEMICAL ENGINEERING SCHOOL OF ENGINEERING AND ENGINEERING TECl-lNotOGY

FEDERAL UNIVERSIty OF TECHNOLOGY MINNA, NIGER STATE.

DECEMBER, 1998.

I

... oJ" ·",·1 \.-'

DECLARATION

I, Udobong Udo Dickson, declare that this project is solely the resnlt of

my work and has never been submitted anywhere for any degree. All literature cited

have been duly acknowledged in the references.

U.U. DICKSON " !.r~ '\ Y',

,., ".( '.'

, "or'

II

CERTIFICATION

This is to certify that this proJect. "Development of Rice-Husk Modified Urea-

Formaldehyde Adhesive" was carried out by DICKSON UDOBONG UDO of the

Department of Cliemical Engineering, School of Engineering and Engineering

Technology, Federal University of Technology, Minna.

DR. M. 0 EDOGA Project Supervisor

DR. J. O. ODIGURE Head of Depmiment

EXTERNAL EXAMINER

. PROF. F. AKINBODE Dean, School of Eng. & Eng. T~ch

III

DATE

DATE

DATE

DATE

DEDICATION

This project is dedicated to my loving parents - Mr. and Mrs U. D. Essien.

tv

ACKNOWLEDGMENT

My profound gratitude goes to my project supervisor - Dr M.O. Edoga, whose

and constructive criticisms made the completion of this work a success.

My special thanks are due to the family of pastor Clem Emekene whose spiritual

financial support also made the completion of this project possible. Appreciation

ue to the entire family of the Glory Reign Assembly, Port Harcourt, members of

. Shem Nuhu Zagbayi, Mrs. Bose Gana, Mr and Mrs Odofin, Mama Princess

".U,,,,"U~l Yisa, Deac. Victor Yos of Joyful Sounds for your financial supports.

o my bossom friend Jide Oladipo, and Toyin Adekoya, Anaja Odekina, Pat Idowu

Lara Adekeye. My special thanks also go to my parents, Mr and Mrs. V.D. Essien for their

support throughout my academic pursuit and thanks to the great ones" THE

" Finally, I give my unparalled thanks to God Almighty, my father, who gave me

grace and strength throughout my academic career.

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ed

Preparation of rice-husk...................... ............. .... ................ .... ...... 10

Drying of rice-husk............................... ............. ......... ..... ..... .... ..... 10

Preparation of U-F resin (neat)....................................................... 10-11

Preparation of modifed U-F resin (Chemically

Mixed modified U-F resin)............................................................ 11 Preparation ofmodffied U-F resin (Physically Mixed

modified U-F Resin') ..................................................................... .

pH determination ............................................................................ .

Determination of Specific Gravity ................................................. . V· 'ty D t rm' t'

ISCOSI e e Ina Ion ............................................................... ..

Results ........................................................................................... .

IR (Infra-red) spectrometer reading ............................................. ..

For neat (BJ ................................................................... : .............. .

For modified sample (chemically mixed, B2) .............................. ..

NMR (Nuclear Magnetic Resonance)

Spectrometer Reading .................................................................. ..

For Neat (BJ ..................................................................... : ............ .

For modified sample (chemically mixed, B2) ................................ ..

Equipment Design.' ..................................................................... .

Problem Statement. ...................................................................... .

Product Specification ................................................................... .

Equipment Selection ..................................................................... .

Raw Materials ............................................................................... .

Process Description ...................................................................... .

Material Balance Over the Reactor ............................................. .. S· .

lzlng ............................................................................................ .

Heat Balance Over the Reactor ................................................... ..

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12

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15 15-16

16-17

18-20

20-28

Datas ................................................................................ .

Costing ......................................................................................... .

Safety ........................................................................................... .

Conclusion/Recommendation ...................................................... .

Conclusion ................................................................................... .

Recommendation ......................................................................... ..

Appendix ..................................................................................... .

References .................................................................................... .

General properties of FurfuraL ..................................................... ..

Fluid Properties of FurfuraL ......................................................... ..

Flammability properties of FurfuraL .............................................. .

. Infra Red (lR) Spectrometry

(For both neat and chemically mixed modified samples)

. Nuclear magnetic resonance (NMR) Spectrometry For Neat Sample

. Nuclear magnetic resonance (NMR) Spectrometry

(For chemically mixed modified samples)

UF Resin Jacketed Reactor

Reflux Condenser

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29-31

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CHAPTER ONE

INTRODUCTION

fonnaldehyde resins were amongst the rlfSUI;ynthetic polymers to be commercialised and \"'~' "

find extensive use today in insulating foams moulding powders and most importantly in

adhesives. They belong to the Class of network (i:,e. cross-linked) polymers known as the

Wood-bonding adhesives are of two types namely; exterior-structural and interior-non-

adhesives. This classification is principally based on their response to moisture and

res IllS, at present - the cheapest and the most versatile wood

are used in interior-grade wood products because of their ability to moisture

above 40°C (Bergin, 1958).

To increase the versatility <;>f urea Iftirmaldehyde adhesives in exterior-structural

aIJIJU'''' .. UJ'VUU, there must be structural modification of the resins so as to increase their water-

-<>1"'nn property (hydrophobility). It is therefore, on this that this present work is initiated. To

this particular goal rice-husk is chosen because of its high content of furfural. Furfural

tum is a good exterior-structural grade adhesive and used as U-F adhesive modifier (Brown

Stigger, 1961).

Overall, the project would inClude synthesis of, neat and modified urea-formaldehyde

as well as the design ofU-F re~ins reactor.

2:2 RA W MATERIALS FOR MANUF ACTllRE OF V-F RESINS 2.2.1 FORMALDEHYDE

Formaldehyde is a highly reactive, pungent smelling, poisonous gas. It is made

by passing air and methanol vapors through a heated copper or platinum gauze. The

resulting fotmaldehyde is dissolved in water. It is highly.rr.~,Gt.ive and can form

methylene glycol:

HCHO + H20~HO- CH2 - OH

HO - CH2 - OH + nHCHO ~HO-CH2 -O(CH2-0)nH

The reaction can continue to produce chains of polyoxymethylene glycol. To prevent

precipitation of the formaldehyde polymer, known as paraformaldehyde, the s01ution

can be stabilized by adding methyl alcohol. A 37% solution of formaldehyde thust be

maintained at a temperature of at least 32°C to prevent precipitation of the polymer: By adding 5-10% methanol, the solution will remain clear if stored at room temperature.

A very highly concentrated fOrin of formaldehyde stabilized with urea is also .' '.' '.'",.' .

available. It is manufactured by Allied chemical co. and is known as UF cohcehttate i

85. The product contains 4.6 moles solids. It is convenient for the mahufacture of I

urea-formaldehyde adhesives, since the user need only add urea to give the desired

urea-formaldehyde ratio, adjust the pH to the desired level, and react the resin to the

desired state of cure before use in his specific application.

Formaldehyde is a toxic gas and may be released from some amino­

formaldehyde resins even after curing. This is true for urea-formaldehyde foam

insulation and for urea-formaldehyde adhesives used in plywood and particle board.

Formaldehyde can irritate the eyes, nose and throat. Formaldehyde has also been found

to cause cancer in lab'oratory animals. Many countries have' CiUopted restrictive

standards limiting the amount of formaldehyde that may be released from particleboard

that is used in the construction of residential housing. West Germany is reported to

have one of the most st~ingent formaldehyde regulations I.

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2.2.2 UREA

Urea is the most important building block for amino resin~ andpla~tics _ first,

because urea-formaldehyde is the largest selling amino resin, and second because urea

is used to make melamine, the amino compound in the second largest selling amino

resin. Urea is also involved in the manufacture of a variety of other amino compounds

that are also used to make amino resins. Urea is now made in immense qUahtities for

use as a fertilizer and'cattle feed supplement l .

Urea is a colorless, odorless solidI, or a white crystalline compound with a .• ; ....• " ",'1", "

melting point of 132.6°C and is highly soluble in water. It is substantially cheaper than

the other intermediate (formaldehyde) used in the resin preparation.

Urea is prepared commercially by the reaction of liquid carbon dioxide and

ammonia in silver-lined autoclaves, at temperatures in the range 135-195°C and

pressures of 70-230 atm. The reaction proceeds by way of ammonium carbamate2 i.e

Ammonium carbamate is first formed but releases a molecule of water to form urea I:

Urea has been obtained from calcium cyanamide via cyanamide

CaCN2 + H2S04 ~ NH2.CN f CaS04

NH2 .CN + H20 ~CO(NH2)2 I 2 The route is now obsolescent.

2.3 CHEMISTRY OF REACTION OF U-F RESINS

Two major chemical reactions are involved in the bonding of amino compounds

together with formaldehyde to produce and cure an amino resin. The first is the

addition' of formaldehyde to the amino group to introduce the hydroxy-methyl group,

also known as the methylol group;

R- NH2 + HCHO ~ R - NH - CH20H

The second reaction is the combination of the methylol group with anactiye

4