CHAPTER 1

INTRODUCTION TO FOAM PRODUCTION

Foam can be defined as a soft light rubber, full of small holes, no

matter how tiny they could be, that has a wide variety of

application. Foam has become a very important material required

for a vast production of so many other materials needed for the

satisfaction of human want. These materials include; vehicle seat,

mattresses and cushion to name but a few. Owing to the vast use

and need for foams, there is now an increase in its production

across the globe.

Foam production can be said to be the process of manufacturing

foam blocks by putting together some chemicals like polyol,

Toluene Diisocynate and others in the right proportion with the

right catalyst, which can be used in the manufacturing of some

finished goods like mattresses, pillow, cushion and other foam

materials.

1
There are various types of foam, which includes:

 Polyurethane foam;

Used for fill, packing, shipping, mattress topper, dog beds,

costumes. Thick pieces will develop "sink" areas after a

short time. Polyurethane foam is really not a high quality of

foam, and will often not return to its original form. Most

times, one cannot guarantee the foam will maintain its

original shape during shipping.

 High density foam;

Sold primarily for mattresses, average sofa and chair

cushions, baywindows, boats, camping pads, etc...

 Evlon foam;

Also known as Lux foam. A "good" foam, typically used for

upper scale furniture seating and mattresses. It is very

buoyant.

2
 High resilience foam;

Used in most types of expensive furniture including yachting

and boating. Makes for an excellent mattress, very buoyant

and resilient.

 Latex rubber foam;

This is a non-allergenic, first type of foam on market,

longest lasting. Used in top of the line products including

mattresses, cushions etc... (Better than High Resilience)

 Supreme foam;

Used primarily for computer and camera cases, packing and

shipping, acoustical dampening and sound proofing. It is

charcoal grey/black in color.

 Rebond foam;

Used as carpet padding, weight equipment, outdoor

furnishing and other covered padding. Widely used in the

3
 hospital. Has very high resiliency and stands up to high

impact / usage.

 Memory foam;

Also known as NASA foam, miracle foam, wonder foam or

viscolastic foam. Developed for space shuttle seating and

used for mattresses and seating. Very dense, conforms to

shape - most unique foam on the market today.

 Closed cell Foam;

Non-water absorbent, non-biodegradable, floats, great

tensile strength, impervious to petroleum. Used in exercise

mats, high impact aerobic equipment, mechanic's box lining

(.25" to .50" thick). Good thermal insulator (hot tub covers).

 Dry fast foam;

Very good for outdoor uses, very resilient and buoyant,

open cell structure. Used filtering, or padding that is subject

to high amounts of liquid.

4
In all the foam types mentioned above, one thing is common and

that is, that they all emanate from the polyurethanes. The

difference in each and every one of them, is dependent on the

nature of some other chemical elements added to it in other to

give it the desirable quality.

Owning to their common relationship to polyurethanes, most

companies have polyurethane foam as the basics for their

production. Therefore, we will be going into the production

process of a polyurethane foam.

5
 CHAPTER 2

THEORY OF POLYURETHANE FOAM PRODUCTION

Polyurethanes are linear polymers that have a molecular

backbone containing carbamate groups (-NHCO2). These groups,

called urethane, are produced through a chemical reaction

between a diisocyanate and a polyol. First developed in late

1930s, polyurethanes are some of the most versatile polymers.

They are used in vast foam production, building insulation, surface

coatings, adhesives, solid plastics, and athletic apparel.

Polyurethanes, also known as polycarbamates, belong to a larger

class of compounds called polymers. Polymers are

macromolecules made up of smaller, repeating units known as

monomers. Generally, they consist of a primary long-chain

backbone molecule with attached side groups. Polyurethanes are

characterized by carbamate groups (-NHCO 2 ) in their molecular

backbone.

6
Synthetic polymers, like polyurethane, are produced by reacting

monomers in a reaction vessel. In order to produce polyurethane,

a step—also known as condensation—reaction is performed. In

this type of chemical reaction, the monomers that are present

contain reacting end groups. Specifically, a diisocyanate (OCN-R-

NCO) is reacted with a diol (HO-R-OH). The first step of this

reaction results in the chemical linking of the two molecules

leaving a reactive alcohol (OH) on one side and a reactive

isocyanate (NCO) on the other. These groups react further with

other monomers to form a larger, longer molecule. This is a rapid

process which yields high molecular weight materials even at

room temperature. Polyurethanes that have important

commercial uses typically contain other functional groups in the

molecule including esters, ethers, amides, or urea groups.

BRIEF HISTORY OF POLYURETHANE

Polyurethane chemistry was first studied by the German chemist,

Friedrich Bayer in 1937. He produced early prototypes by reacting

7
toluene diisocyanate reacted with dihydric alcohols. From this

work one of the first crystalline polyurethane fibers, Perlon U, was

developed. The development of elastic polyurethanes began as a

program to find a replacement for rubber during the days of

World War II. In 1940, the first polyurethane elastomers were

produced. These compounds gave millable gums that could be

used as an adequate alternative to rubber. When scientists found

that polyurethanes could be made into fine threads, they were

combined with nylon to make more lightweight, stretchable

garments.

In 1953, the first commercial production of a flexible polyurethane

foam was begun in the United States. This material was useful for

foam insulation. In 1956, more flexible, less expensive foams were

introduced. During the late 1950s, moldable polyurethanes were

produced. Over the years, improved polyurethane polymers have

been developed including Spandex fibers, polyurethane coatings,

and thermoplastic elastomers.

8
THE CHEMISTRY OF POLYURETHANE

Polyurethanes are in the class of compounds called reaction

polymers, which include epoxies, unsaturated polyesters, and

phenolics. A urethane linkage is produced by reacting an

isocyanate group, -N=C=O with a hydroxyl (alcohol) group, -OH.

Generalised polyurethane reaction

Polyurethanes are produced by the polyaddition reaction of a

polyisocyanate with a polyalcohol (polyol) in the presence of a

catalyst and other additives. In this case, a polyisocyanate is a

molecule with two or more isocyanate functional groups, R-

(N=C=O)n ≥ 2 and a polyol is a molecule with two or more hydroxyl

functional groups, R'-(OH)n ≥ 2. The reaction product is a polymer

containing the urethane linkage, -RNHCOOR'-. Isocyanates will

react with any molecule that contains an active hydrogen.

Importantly, isocyanates react with water to form a urea linkage

and carbon dioxide gas; they also react with polyetheramines to

9
form polyureas. Commercially, polyurethanes are produced by

reacting a liquid isocyanate with a liquid blend of polyols, catalyst,

and other additives. These two components are referred to as a

polyurethane system, or simply a system. The isocyanate is

commonly referred to in North America as the 'A-side' or just the

'iso'. The blend of polyols and other additives is commonly

referred to as the 'B-side' or as the 'poly'. This mixture might also

be called a 'resin' or 'resin blend'. In Europe the meanings for 'A-

side' and 'B-side' are reversed. Resin blend additives may include

chain extenders, cross linkers, surfactants, flame retardants,

blowing agents, pigments, and fillers.

The first essential component of a polyurethane polymer is the

isocyanate. Molecules that contain two isocyanate groups are

called diisocyanates. These molecules are also referred to as

monomers or monomer units, since they themselves are used to

produce polymeric isocyanates that contain three or more

isocyanate functional groups. Isocyanates can be classed as

aromatic, such as diphenylmethane diisocyanate (MDI) or toluene

10
diisocyanate (TDI); or aliphatic, such as hexamethylene

diisocyanate (HDI) or isophorone diisocyanate (IPDI). An example

of a polymeric isocyanate is polymeric diphenylmethane

diisocyanate, which is a blend of molecules with two-, three-, and

four- or more isocyanate groups, with an average functionality of

2.7. Isocyanates can be further modified by partially reacting them

with a polyol to form a prepolymer. A quasi-prepolymer is formed

when the stoichiometric ratio of isocyanate to hydroxyl groups is

greater than 2:1. A true prepolymer is formed when the

stoichiometric ratio is equal to 2:1. Important characteristics of

isocyanates are their molecular backbone, % NCO content,

functionality, and viscosity.

The second essential component of a polyurethane polymer is the

polyol. Molecules that contain two hydroxyl groups are called

diols, those with three hydroxyl groups are called triols, et cetera.

In practice, polyols are distinguished from short chain or low-

molecular weight glycol chain extenders and cross linkers such as

ethylene glycol (EG), 1,4-butanediol (BDO), diethylene glycol

11
(DEG), glycerine, and trimethylolpropane (TMP). Polyols are

polymers in their own right. They are formed by base-catalyzed

addition of propylene oxide (PO), ethylene oxide (EO) onto a

hydroxyl or amine containing initiator, or by polyesterification of a

di-acid, such as adipic acid, with glycols, such as ethylene glycol or

dipropylene glycol (DPG). Polyols extended with PO or EO are

polyether polyols. Polyols formed by polyesterification are

polyester polyols. The choice of initiator, extender, and molecular

weight of the polyol greatly affect its physical state, and the

physical properties of the polyurethane polymer. Important

characteristics of polyols are their molecular backbone, initiator,

molecular weight, % primary hydroxyl groups, functionality, and

viscosity.

PU reaction mechanism catalyzed by a tertiary amine

12
 carbon dioxide gas formed by reacting water and

isocyanate

The polymerization reaction is catalyzed by tertiary amines, such

as dimethylcyclohexylamine, and organometallic compounds, such

as dibutyltin dilaurate or bismuth octanoate. Furthermore,

catalysts can be chosen based on whether they favor the urethane

(gel) reaction, such as 1,4-diazabicyclo[2.2.2]octane (also called

DABCO or TEDA), or the urea (blow) reaction, such as bis-(2-

13
dimethylaminoethyl)ether, or specifically drive the isocyanate

trimerization reaction, such as potassium octoate.

One of the most desirable attributes of polyurethanes is their

ability to be turned into foam. Blowing agents such as water,

certain halocarbons such as HFC-245fa (1,1,1,3,3-

pentafluoropropane) and HFC-134a (1,1,1,2-tetrafluoroethane),

and hydrocarbons such as n-pentane, can be incorporated into the

poly side or added as an auxiliary stream. Water reacts with the

isocyanate to create carbon dioxide gas, which fills and expands

cells created during the mixing process. The reaction is a three

step process. A water molecule reacts with an isocyanate group to

form a carbamic acid. Carbamic acids are unstable, and

decompose forming carbon dioxide and an amine. The amine

reacts with more isocyanate to give a substituted urea. Water has

a very low molecular weight, so even though the weight percent

of water may be small, the molar proportion of water may be high

and considerable amounts of urea produced. The urea is not very

soluble in the reaction mixture and tends to form separate "hard

14
segment" phases consisting mostly of polyurea. The concentration

and organization of these polyurea phases can have a significant

impact on the properties of the polyurethane foam.[11]

Halocarbons and hydrocarbons are chosen such that they have

boiling points at or near room temperature. Since the

polymerization reaction is exothermic, these blowing agents

volatilize into a gas during the reaction process. They fill and

expand the cellular polymer matrix, creating a foam. It is

important to know that the blowing gas does not create the cells

of a foam. Rather, foam cells are a result of blowing gas diffusing

into bubbles that are nucleated or stirred into the system at the

time of mixing. In fact, high-density microcellular foams can be

formed without the addition of blowing agents by mechanically

frothing or nucleating the polyol component prior to use.

Surfactants are used to modify the characteristics of the polymer

during the foaming process. They are used to emulsify the liquid

components, regulate cell size, and stabilize the cell structure to

prevent collapse and surface defects. Rigid foam surfactants are

15
designed to produce very fine cells and a very high closed cell

content. Flexible foam surfactants are designed to stabilize the

reaction mass while at the same time maximizing open cell

content to prevent the foam from shrinking. The need for

surfactant can be affected by choice of isocyanate, polyol,

component compatibility, system reactivity, process conditions

and equipment, tooling, part shape, and shot weight.

Though the properties of the polyurethane are determined mainly

by the choice of polyol, the diisocyanate exerts some influence,

and must be suited to the application. The cure rate is influenced

by the functional group reactivity and the number of functional

isocyanate groups. The mechanical properties are influenced by

the functionality and the molecular shape. The choice of

diisocyanate also affects the stability of the polyurethane upon

exposure to light. Polyurethanes made with aromatic

diisocyanates yellow with exposure to light, whereas those made

with aliphatic diisocyanates are stable.

16
Softer, elastic, and more flexible polyurethanes result when linear

difunctional polyethylene glycol segments, commonly called

polyether polyols, are used to create the urethane links. This

strategy is used to make spandex elastomeric fibers and soft

rubber parts, as well as foam rubber. More rigid products result if

polyfunctional polyols are used, as these create a three-

dimensional cross-linked structure which, again, can be in the

form of a low-density foam.

An even more rigid foam can be made with the use of specialty

trimerization catalysts which create cyclic structures within the

foam matrix, giving a harder, more thermally stable structure,

designated as polyisocyanurate foams. Such properties are

desired in rigid foam products used in the construction sector.

Careful control of viscoelastic properties — by modifying the

catalysts and polyols used —can lead to memory foam, which is

much softer at skin temperature than at room temperature.

17
There are then two main foam variants: one in which most of the

foam bubbles (cells) remain closed, and the gas(es) remains

trapped, the other being systems which have mostly open cells,

resulting after a critical stage in the foam-making process (if cells

did not form, or became open too soon, foam would not be

created). This is a vitally important process: if the flexible foams

have closed cells, their softness is severely compromised, they

become pneumatic in feel, rather than soft; so, generally

speaking, flexible foams are required to be open-celled.

The opposite is the case with most rigid foams. Here, retention of

the cell gas is desired since this gas (especially the fluorocarbons

referred to above) gives the foams their key characteristic: high

thermal insulation performance.

A third foam variant, called microcellular foam, yields the tough

elastomeric materials typically experienced in the coverings of car

steering wheels and other interior automotive components.

18
 RAW MATERIALS FOR POLYURETHANE FOAM PRODUCTION

In polyurethane foam production, various raw materials are

required and this includes:

 A compound with an isocyanate group.

 A compound with an alcohol group.(polyol)

 Additives

o Surfactants

o Blowing agents

o Flame retardant

o Light retarders

o Fillers.

Brief explanation of the major ones.

Isocyanates

Isocyanates with two or more functional groups are required for

the formation of polyurethane polymers. Volume wise, aromatic

isocyanates account for the vast majority of global diisocyanate

production. Aliphatic and cycloaliphatic isocyanates are also

19
important building blocks for polyurethane materials, but in much

smaller volumes. There are a number of reasons for this. First, the

aromatically linked isocyanate group is much more reactive than

the aliphatic one. Second, aromatic isocyanates are more

economical to use. Aliphatic isocyanates are used only if special

properties are required for the final product. For example, light

stable coatings and elastomers can only be obtained with aliphatic

isocyanates. Even within the same class of isocyanates, there is a

significant difference in reactivity of the functional groups based

on steric hindrance. In the case of 2,4-toluene diisocyanate, the

isocyanate group in the para position to the methyl group is much

more reactive than the isocyanate group in the ortho position.

The two most important aromatic isocyanates are toluene

diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). TDI

consists of a mixture of the 2,4- and 2,6-diisocyanatotoluene

isomers.

Polyols

20
The other reacting species required to produce polyurethanes are

compounds that contain multiple alcohol groups (OH), called

polyols. Materials often used for this purpose are polyether

polyols, which are polymers formed from cyclic ethers. They are

typically produced through an alkylene oxide polymerization

process. They are high molecular weight polymers that have a

wide range of viscosity. Various polyether polyols that are used

include polyethylene glycol, polypropylene glycol, and

polytetramethylene glycol. These materials are generally utilized

when the desired polyurethane is going to be used to make

flexible foams or thermoset elastomers.

Polyester polyols may also be used as a reacting species in the

production of polyurethanes. They can be obtained as a byproduct

of terephthalic acid production. They are typically based on

saturated aromatic carboxylic acids and diols. Branched polyester

polyols are used for polyurethane foams and coatings. Polyester

polyols were the most used reacting species for the production of

21
polyurethanes. However, polyether polyols became significantly

less expense and have supplanted polyester polyols.

Catalysts

Polyurethane catalysts can be classified into two broad categories,

amine compounds and organometallic complexes. They can be

further classified as to their specificity, balance, and relative

power or efficiency.

Organometallic compounds based on mercury, lead, tin (dibutyltin

dilaurate), bismuth (bismuth octanoate), and zinc are used as

polyurethane catalysts.

Surfactants

Surfactants are used to modify the characteristics of both foam

and non-foam polyurethane polymers. They take the form of

polydimethylsiloxane-polyoxyalkylene block copolymers, silicone

oils, nonylphenol ethoxylates, and other organic compounds. In

22
foams, they are used to emulsify the liquid components, regulate

cell size, and stabilize the cell structure to prevent collapse and

sub-surface voids. In non-foam applications they are used as air

release and anti-foaming agents, as wetting agents, and are used

to eliminate surface defects such as pin holes, orange peel, and

sink marks.

SIGNIFICANCE OF VARIOUS CHEMICALS, ELEMENTS AND

COMPOUNDS USED IN FOAM PRODUCTION.

Just as we said before, the following are the elements/chemicals

and their significance;

1. TOULENE DIISOCYNATE (TDI);

This is a major chemical used in foam production. It is a very toxic

chemical and the most basic required for production.

2. POLYPROPYLENE GLYCOL (POLYOL);

This is a major chemical needed also to dilute the toluene

diisocyanate.

23
3. METHLY CHLORIDE;

This is a colorless compound which is very cold to the touch. It

acts as a blowing agent during production and also used in

flushing the mixer head after production. it is also used in cleaning

the trough after production.

4. SILICONE;

This is used for stabilization and smoothening of the foam.

5. AMINE;

This is used for curing. Curing is the ability of foam to dry easily.

6. COLORANT;

This adds color to the foam. It could be blue or pink depending on

what is needed.

7. Tin;

24
This is acting as a binding agent in foam production.

8. WATER;

This also aid in reducing the temperature of the process. It also

helps in diluting the mixed chemicals.

FOAM PRODUCTION PROCESS.

For a foam block to be manufactured, there are some major steps

or processes which must be undergone and they include:

1. Pumping of chemicals

2. Cooling of pumped chemicals

3. Injection and mixing of chemicals in the foam plant machine

4. Production and conveying

5. Cutting

1. Pumping of chemicals

25
In the production of foam, there are three major chemicals used

which are;

 Polypropylene glycol(polyol)

 Toluene Diisocynate(TDI)

 Methyl chloride

Toluene Diisocynate is a very toxic chemical which can choke one

to death while polypropylene is a chemical used to dilute toluene

Diisocynate and it is not toxic.

There are other elements and compounds which may serve as

catalysts or that may add other qualities to foam and these

chemical, elements and compounds include;

 Zinc

 Silicone

 Colorants

 Tin

 Amine

 Water

26
These various elements, compounds and chemicals have various

useful effects on a foam block, but the various functions would be

discussed later.

Pumping of chemical is a process of filling the various chemical

tanks in the chemical room. This is done by passing the chemicals

through separate pipes with the aid of a pump attached to each

tank. Here, the major chemicals are concerned i.e. TDI, polyol and

methyl chloride.

The other elements and compounds are not kept in the chemical

room rather, they are kept very close to the foam plant machine

in a smaller container.

2. Cooling of chemical

The pumped chemicals are kept or stored in their various tanks in

a chemical room which is more or less like a cool room. This is

because a cooling machine has being attached to the room. This is

very important, owing to the fact that a fire outbreak could occur,

if the chemicals are heated up, most especially the Toluene

27
Diisocynate. To each of the tanks, is a pump attached to enhance

injection and pumping of the chemicals.

3. Injection and mixing of the chemical in the foam plant

machine

Injection is the process of transferring the amount of or

percentage of feed or chemical needed for production from the

chemical room to the foam plant machine. This injection is done

by the means of a pipe which has a pump attached to it.

After the injection, all the chemicals, elements and compounds

needed for the production meet at a part of the foam plant

machine known as the mixer head, where they all mix together.

4. Production and conveying

The production process is a continuous process. Hence, the

chemicals enter the system which is more or less like a conveyor.

There in the conveyor, the chemicals start rising while the

conveyor conveys them. There is a rising distance and that is the

distance at which a particular foam must have set. Here, the rising

28
point was between 95cm-98cm. This is continuous until the whole

production has been done.

5. Cutting

At one part of the conveyor, few centimeters away from the rising

point is an automated cutting machine which can also be manually

operated .the cutter or blade cuts the long foam block in blocks of

equal sizes to enhance carriage.

As soon as cutting has been done, everything about production

has finished.

Finally, the work place is cleared and the mixer head is flushed

with methyl chloride and the trough through which the chemicals

go into the conveyor is cleaned efficiently with CH3CL also, in

order to remove any particle that must have glued to it in the

course of the production. Then, the production room is left till the

next day In order to allow all the toxic gases escape before the

final arrangement.

29
 The foam blocks are sent to the conversion unit in order to be

converted to pillow, mattresses, cushion and so on.

The diagrammatic representation of a foam production process

flow diagram is as shown below.

polyol

Mixer head
conveyor
TDI Output(foam)

MeCl

H20 silicon tin colour amine zinc

pump

An industry that is also into rebond foam production, continues

after the production of polyurethane by putting the foam block

which have been cut into a foam bond machine.

A foam bond machine contains an automated foam grinder,

known as a crumb machine, which grinds foam blocks into smaller

pieces and mixes them up with a gum like liquid as to enable them

30
bond with each other. Then the machine has a large compressing

flat surface which compresses the foam pieces which are now in a

container that has the desired shape. When the flat surface

compresses the foam, they are bonded together into the desirable

shape. Then you have the rebond foam widely known in this part

of the country as orthopedic foam.

In an ideal foam production firm, there are three major units and

they are:

1. The production unit

2. The conversion unit

3. The marketing unit

Production unit

This is the unit in which the actual production of the foam block

takes place. All the production machineries like the omega mass

computerizing machine, bonded machine, grinders, pumps and

chemical storage tanks are located.

31
The conversion unit

This is the next important unit after the production unit. Here the

foam blocks produced are converted into mattresses, pillow and

cushion. This unit comprises of an automated cutter and sewing

machines. Here, the bare foam blocks are given beautiful and

attractive coverings.

The marketing unit

This unit is also known as the sales unit. This unit is where finished

goods are sold and marketed.

The first to unit can be combined in one to give two major units.

Foam production is quite amazing because of the way liquid

chemicals rise into foam blocks.

32
 CHAPTER 3

APPARATUS AND PROCEDURE

Apparatus used in foam production

This includes the machines, chemicals and elements used in foam

production. They are;

 Machines include

 Rebond foam machine and crumb

 Compressing machine

 Omega mass computerizing machine or maxfoam

machine

 Charts

 Chemicals and elements

 Polypropylene glycol(polyol)

 Toluene Diisocynate(TDI)

 Methyl chloride

 Zinc

 Silicone

33
  Colorants

 Tin

 Amine

 Water

PROCEDURES IN FOAM PRODUCTION

The steps involved for a successful foam production, is as shown

below.

 1. Pumping of chemicals

 2. Cooling of pumped chemicals

 3. Injection and mixing of chemicals in the foam plant

machine

 4. Production and conveying

 5. Cutting

The above procedures have been discussed at length in the theory

part of this piece of work.

34
 CHAPTER 4

ANALYSIS OF THE FOAM PLANT MACHINE

The machine used in Group enterprises is called Omega

Computerizing machine. It can also be said to be a continuous

foam plant machine due to the fact that the process is continuous

(i.e. it keeps working until the last output is gotten).

In the machine, other elements meet polyol at the mixer head.

The mixer head has a motor that runs between 3500rpm-

4000rpm.The machine has a conveyor which has side papers to

avoid running off of the mixed chemicals.

A cutting blade is attached say at 100cm mark of the conveyor,

which cuts the blocks into equal sizes.

The trough is connected to the mixer head by the means of a pipe

which supplies chemicals to the trough from where the chemical

are poured into the conveyor.

35
As we said before, the machine is computerized. Hence, the

various percentages needed for a given production is typed into

the computer while the computer monitors the operation at a

given conveyor speed and the mixer speed. All these could be

seen on the screen of the monitor.

The table of the process is shown on the monitor as shown on

fig.1 of the appendix.

The feeding process of the data into the system is a very

meticulous process because any slight error or mistake can lead to

the production of an undesirable foam block which automatically

leads to loss and wastage of raw materials. This is the reason why

there is percentage error in the diagram above. This a way

through which the system corrects slight errors fed in to the

system.

36
 CONCLUSION

Chemical engineering is all about process brought about by the

application of mathematics, physics and chemistry, of which foam

production underwent some processes before coming to a

finished product.

A chemical engineer is highly interested in the inputs, reactions

going on in the system, the accumulation and several other

processes going on within and without the system. Hence

chemical engineer is more interested in the reactants, their

reactions and the products formed.

Owing to the nature of the interest of a chemical engineer, then

the need for him in a foam manufacturing plant can never be over

emphasized. This is because foam production, is all about the

general reaction between a higher isocyanate group and an

alcohol group.

A chemical engineer also performs the function of quality control

in order to ensure a quality polyurethane foam. In order to

37
achieve this, he monitors the product during all phases of

production. These inspections begin with an evaluation of the

incoming raw materials by quality control chemists. They test

various chemical and physical characteristics using established

methods. Some of characteristics that are tested include the pH,

specific gravity, and viscosity or thickness. Additionally,

appearance, color, and odour may also be examined.

Manufacturers have found that only by strictly controlling the

quality at the start of production can they ensure that a consistent

finished product will be achieved.

After production, the polyurethane product is tested.

Polyurethane coating products are evaluated in the same way the

initial raw materials are checked. Also, characteristics like dry

time, film thickness, and hardness are tested. Polyurethane fibres

are tested for things such as elasticity, resilience, and absorbency.

Polyurethane foams are checked to ensure they have the proper

density, resistance, and flexibility.

38
In conclusion, a foam process plant is purely based on various

chemical engineering processes, starting from the pumping of the

chemicals, to the mixing and finally the output (the foam block).

Hence, from this we could see that some unit operations like

pumping, cooling, distillation and so on were applied.

A chemical engineer has so much to do in the production of foam

blocks. Hence, the production of a foam block can be said to be a

chemical process.

39
 REFERENCE

 Harrington, Ron, Hock, Kathy;”Flexible Polyurethane

Foams”, midland. The Dow chemical company: 1991

 Oertel, Gunter,” Polyurethane Handbook”, New York.

Macmillan Publishing Co. Inc. 1985

 Ulrich, Henri, “Chemistry and Technology Of Isocynates”,

New York: John Wiley & Sons Inc.1996

 Experience from SIWES 400l at group enterprises Nig.

Limited. Poly foam industry

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 APPENDIX
CONVEYOR SPEED……………..…………………………………4.0m/s

MIXER SPEED………………………………………………………..3569rpm

CHEMICAL PPH PBW ACTUAL ERROR(%) USED(%)

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