PHENOLIC RESINS

PROF. PRAKASH MAHANWARPROF. PRAKASH MAHANWAR

HEAD, DEPT.OF POLYMER TECHNOLOGY &

DEPT. OF SURFACE COATINGS

INSTITUTE OF CHEMICAL TECHNOLOGY

MATUNGA, MUMBAI-400 019

Phenolic resins are the oldest commercially

manufactured synthetic polymer. They were first

'invented' by Leo Hendrik Baekland in 1907. He

was the one to develop an economical method towas the one to develop an economical method to

convert these resins to moldable formulations which

were transformed by heat and pressure to hard and

resistant molded parts.

Why Phenolic Resins??

� Phenolic resins are distinguished by broad array of application areas amongst Thermosetting and Thermoplastic resins.

� They are relatively inexpensive and highly versatile having vital role in construction, automotive, electrical, and appliance industries.

� They are irreplaceable materials for selective high technology applications offering high reliability under severe circumstances.

Continued…

� Prominent features of Phenolic Resins are:

- Excellent thermal behavior

-High Strength level

-Long thermal and mechanical stability.

-Excellent fire, smoke,and low toxicity characteristics.

-Excellent electrical and thermal insulating capabilities.

-Excellent cost performance characteristics.

Market scenario

� According to the Chemical Economics the global market for Phenolic resins had reached 2.46 million tonnes by 1997 (on a 100% resin weight basis) with 39% of demand in NAFTA, 24% in Europe, 5% in 39% of demand in NAFTA, 24% in Europe, 5% in Japan and the balance of 33% in other regions in 2005 where as in 2008 the rate of increase in worldwide market was 8-12% than 2005.

world consumption of Phenolic resins

Phenolic resins are obtained by step growth polymerization ofdifunctional monomers (aldehydes) with monomers of functionalitygreater than 2 (Viz, Phenol, substituted Phenols or combination ofphenols).Key factors in the design of the desired phenolic resin are:

- Molar ratio of F to P- Mode of catalysis: Acid, base, metal salt, enzyme.

Basic Chemistry

- Mode of catalysis: Acid, base, metal salt, enzyme.-Liquid, Solid, dispersion-Thermoplastics or thermosetting

Low to medium Mw are considered as “ Reactive intermediates whichcan be cured or undergo various transformation reactions via reactivehydroxyl group viz, Epoxy,allyl, cyanate or form new ring structure.

REACTION OF PHENOLAND ALDEHYDE UNDER ACIDIC OR BASICCATALYST ARE EXOTHERMIC REACTIONS ( SIDE REACTIONS DUETO EXOTHERM NEEDS TO BE AVOIDED)

PHENOLIC RESINS

THERMOPLASTIC RESINS NOVOLAC RESINSFIP< 1

THERMOSETTING RESINS RESOL RESINS

FIP>1MONOMERS:A. Phenol-

OH

CH 3

OH

CH 3CCH 3

OH

(CH 2 ) 7 CH 3

OH

OH

CH 3C

CH 3

CH 3 (CH 2 ) 7 CH 3

PHENOL CRESOL p-t-BUTYL

(o/m/p) PHENOL

p-OCTYL

PHENOL

p-PHENYL

PHENOL

C

C 15 H 27CH 3

OH

(CH 2 ) 8

OH

OH

OH

CH 3

CH 3

OH

p-NONYL

PHENOL

RESORCINOL CARDANOL BISPHENOL 'A'

HO

RAW MATERIAL AND CATALYST

� - Phenol, o,m,p-Cresol, p-tert Butylphenol, p-tert Octylphenol,

p-Tert Nonylphenol, (2,3), (2,4), (2,5), (2,6), (3,4), (3,5) –

Xylenol, Resorcinol, Bisphenol A, Bisphenol-F, CNSL, BNSL ,

etc.

� - Formaldehyde, Acetaldehyde, Propionaldehyde, n-

butyraldehyde, Isobutyraldehyde, Glyoxal, Furfural, etc.butyraldehyde, Isobutyraldehyde, Glyoxal, Furfural, etc.

� Catalyst:

-Acid: Organic Acids and Mineral acids

-Base: NaOH, KOH

-Metal salts

-Enzymes

Contd.� Mode of catalysis and molar ratio of F to P decides the type and property of

Phenolic resin.

� Mode of Catalysis dictates the overall property of Resin.

� Depending on type of catalyst and ratio:

� Base catalyst: Resol, F/P >1, Liquid, solid, solution/limited stability

� Acid Catalyst: : Novolak, F/p <1, Solid, stable

� Metal Salts: Resol/Novolak, F/P >1, Liquid/Solid , Varying stability

� Enzymes: Pseudo Novolak, No ( CH2O), Solid, stable.

� Phenols of lower functionality are used to incorporate special properties in the resin.

� Formaldehyde is preferred because of its high reactivity and freedom from side

reactions

VARYING F/P RATIO, TYPE OF CATALYST ONE CAN TAILOR THE PRODUCT WITH:

- Required Melting Range

- Required Molecular weight

- Required functional groups available for modifications.

Three reaction sequences must be considered:

1. Formaldehyde addition to phenol.

2. Chain growth or prepolymer formation.

3. Cross linking or curing reaction.

PHENOLIC RESIN PROCESSSES

PHENOL

+FORMALDEHYDE (EXCESS)

+BASIC CATALYST

PHENOL (EXCESS)

+FORMALDEHYDE

+ACIDIC CATALYST

RESOLES

(THERMOSETTING RESINS)NOVOLAC

(THERMOSETTING RESINS)NOVOLAC

(THERMOSETTINGRESINS)

RESITE CURED RESINS

ONE STAGE PROCESS TWO STAGE PROCESS

Phenolic Resin Chemistry

Formaldehyde Reactions

-Monomers react with formaldehyde under different

conditions to make different products

-Reacting under acid conditions yields thermoplastic

resins (Novolaks)resins (Novolaks)

-Reacting under base conditions yields reactive resins

(Resoles)

-Resole resins can be used for curing of elastomers

Curing Of Resin

� Complex polymer with multiple reactive sites (resole resin)

� Undergoes multiple reactions simultaneously

� Activated by halogens (resinous, elastomeric,or metallic salts)� Activated by halogens (resinous, elastomeric,or metallic salts)

� Requires zinc source for best results

Two prepolymers types are obtained depending

on pH

Type of phenolic resin Novolac Resols

Type of reaction Electrophilic aromatic substitution

Nucleophilic mechanism

Medium (pH) Acidic medium(1-5) Alkaline medium(>7)

Molar ratio P/F 1:0.80 1:1 to 1:3

Type of polymer Linear or slightly branched

Branched

Characteristic property Low MW, soluble and permanently fusible

Insoluble and infusible

Varients and their EffectGeneral Ratio: p,p’:o,p’:o,o’1:2:1

� Catalyst:

� 4-6 pH With Divalent metal salts as

catalyst: High Ortho (57-58%: o-o,

40-42%: o-p and 2-3% p-p)

� F/P Ratio : Softening Range

� 1:065 : 60-70

� 1:075 : 70-75� Oxalic Acid: (25-26%: o-o, 48-50%: o-

p and 25-30% p-p)

� Phosphoric Acid: (23-25%: o-o, 50-

52%: o-p and 25-30% p-p)

� Sulphuric Acid : (25-26%: o-o, 45-

50%: o-p and 25-30% p-p)

� 1:075 : 70-75

� 1:085 : 80-100

Batch Calculations: Novolak

� 100 gm batch of Novolak:

Phenol + Formaline----� 100 gm Novolak Resin +n Water

1 n ( Mole wt of Phenol) + 0.8 n ( Mol wt of HCHO)= 100 gm+ 18xn gms

94n + 0.8n x 30 = 100+18n

94n + 24n =100

100n = 100

n = 1

Quantity of 100% pure Phenol= 94 x1.18gmsQuantity of 100% pure Phenol= 94 x1.18gms

Assume 96% pure Phenol

Actual weight of Phenol = 97.91 gms

Quantity of 100% pure formaldehyde= 24 gms

Assume 35% solution of Formaldehyde

Actual weight of Formaldehyde = 68.57

Catalyst ( Oxylic Acid) 1.5% mole on Phenol = 0.944 gms

Actual weight of Oxalic Acid = H00C-COOH.2H2O ( Mole wt 126 , Eq Wt. 63)

Resol

� 100 gm batch of Resol:

Phenol + Formaline----� 100 gm Resol Resin + 1n Water

1 n ( Mole wt of Phenol) + 1.5 n ( Mol wt of HCHO)= 100 gm+ 18n gms

94n + 1.5n x 30 = 100+18n

94n + 45n =100+18n

121n = 100

n = 0.826n = 0.826

Quantity of 100% pure Phenol= 77.644 gms

Assume 96% pure Phenol

Actual weight of Phenol = 80.88 gms

Quantity of 100% pure formaldehyde= 24.7 gms

Assume 35% solution of Formaldehyde

Actual weight of Formaldehyde = 70.8gm

Catalyst ( NaOH) 1.5% mole on Phenol = 1.21 gms

Actual weight of NaOH = ( Mole wt 40 , Eq. Wt. 40)

Steps in Resin Manufacture (Bettleheim and Nihlberg)

� Warming up time;

� Ripening, the time at condensation temperature before the time starts to precipitates;

� Post ripening, the time is held at condensation temperature after resin separates from the aqueous phase;

� End Point Check: Alcohol Solubility, Free Phenol Content, and � End Point Check: Alcohol Solubility, Free Phenol Content, and Gelation time

� Distillation;

� Concentration, the period the resin is held under vacuum and heated to advanced to the desired viscosity;

� Cooling.

Chek Points

� A. Free Formalin:

Sample+ Acetone+25ml, 10% Hydroxylamine Hydrochloride +

Bromophenol Blue V/s 0.1N NaOH (Yellow to Violet)

% Free Formalin= ( B-S) X NX 3.003

-----------------------

W

B. Free Phenol:B. Free Phenol:

Sample ( distillate)+ 25 ml Brominating Solution+ 10 ml of 10%

KI V/s 0.1N Sodium Thisulphate using Starch solution ( Blue

to) Colorless

% Free Phenol= ( B-S) x 0.001566x100xV

--------------------------------

V

Different types of phenolic resinsThere are two types of phenolic resin - Novolac and ResolWhere Novolac is two stage compound. And Resol is one stage compound.

Phenolic resin Modifications

� Use of phenol derivatives like alkyl phenols.

� Etherification of the methylol group or phenolic hydroxyl group.

� Reaction with unsaturated compounds like reactions with rosins.

� Physical modification such as mixing with vinyl resins or rubber.

� Reaction with epoxide compounds or poly isocyanates.

� Reaction with inorganic acids or inorganic compounds.

Different Modification of Phenolic Resin

Epoxy Modification:The resulting products exhibit high strength, strong adhesion,excellent dielectric properties and improved oxidation resistance.

OCH 2-Cl

O-CH 2-CH-CH2-0-+

OH

CH 2

O

CH

CH 2O

CH 2 CH 2

CH 2

O

CH

CH 2O

CH 2

O

CH

CH 2O

n

Condition for preparation of epoxy phenolic resin

1. Ratio of Resol to epoxy resin : 15:85 and 40:60

2. Epoxy equivalent weight : more than 1500

3. Transition temperature : about 750C

4. Stoved temperature : over 1800C

5. Curing catalyst : phosphoric acid or organic 5. Curing catalyst : phosphoric acid or organic

phosphates

Chemistry : The hydroxy methyl groups of the Resol react with the

hydroxyl groups of the epoxy resin in addition to the reaction of the

phenolic hydroxyl groups with the epoxide groups to form cured,

flexible coatings.

Properties:

Combination of resols with epoxy resins are of high suitability in the

production of stoving enamels which are cured at above 2000C to give

chemical resistant, highly elastic and firmly adhering coatings.

Applications:

1. Used in marine anti-fouling paints in combination with chlorinated rubber.1. Used in marine anti-fouling paints in combination with chlorinated rubber.

2. Used in interior and exterior coatings for packaging, drums and cans.

3. Coating of panels for containers and packages for storage and packaging

of food stuffs and other products.

*Epoxies made with Bis F, a Bis F and Novolac mixture, or Novolac resin

exhibit greatly improved chemical and heat resistance compared to the much

more common Bis A epoxies*

2. Diisocyanates

� Fast curing.

� Used as Single component polyurethane coating.

� Used as crosslinkers in polyester powder coatings.

� Suceptible to thermal dissociation.

Urea, melamine Modification

� Application in particle boards, plywood, mineral fibre bonding, foundry

OH

CH2 OH

+ H2N-C-NH2-H2O

CH2-NH-C-NH2

OOH O

resins and laminates.

� Improvement of flame retardant property.

Using Imide precursors

OHONH2 NH-C-

O

COOH

O

C COR

COOCH2

OH

CH2 OH

� Improvement in higher temperature characteristics of phenolics

Rosin acid-modified phenolic resins

� They render oil solubility to Phenolic resin, good through drying of the

film, high hardness, good gloss high chemical resistance and high

abrasion resistance

� Rosin modified phenolic resins are used in printing inks, in oil lacquers� Rosin modified phenolic resins are used in printing inks, in oil lacquers

and in additives to alkyd paints because of their good compatibility with

natural oils in which they improve the drying and gloss.

� They are used in primers, Anticorrosive Coatings, as fillers, Putties.

Phenol Ester Resins

� In these resins, the phenolic hydroxyl group is esterfied.

� These are important for the plastic sector.

� Phenolic resins are combined with saturated polyesters in order to improve their flexibility

Phenol Ether Resins

� In these resins, phenolic hydroxyl group is etherified.

� These include

1. Epoxy-Novolacs.

2. Allyl ether resols.

3. Water soluble binder system.

4. Phenol ethers with the ether group as polymer linking member.

Alkyl phenol resins

� Starting material : para and ortho substituted phenols

� Suitable for boiling down with unsaturated fatty oils imparting

hardness and resistance properties to these systems at a

temperature of 240-2600C

� Ratio of oil to resin : > 2:1� Ratio of oil to resin : > 2:1

Applications

� Oil and heat reactive resins.

� Tackifiers for rubber processing.

� Marine varnishes.

� Glazes.

� Adhesives

Alkyl phenol resin dispersions

The boiling of thermoplastic alkyl phenol resins with oils gives rise to

products which can be dispersed in aliphatic or aromatic hydrocarbons.

Properties

1. Good adhesion.1. Good adhesion.

2. Abrasion resistance.

3. Good water resistance.

Applications

1. Anticorrosion primers.

2. Quick drying road marking paints.

3. Protective coating on metals.

Boron-modified phenolic resins

-The prepared BPR is intended for use as the innermost lining in a multilayer

composite for tank armor and related future applications.

-The usage of borates in enhancing flame retardancy of phenolic resin

triphenyl borate (TPB)

paraformaldehyde (PF)

Silicon modified resin

� The addition of silicon compounds for improval of thermal resistance of phenol formaldehyde resins was recommended by E.G. Rochow way back in 1941.

� The modification is performed by chemical reaction of silicones or siloxanes containing reactive groups with phenolic compounds or by a mixture of components.

� The addition of silanes as adhesion promoters is widespread. Example: � The addition of silanes as adhesion promoters is widespread. Example: mineral wool mats, foundry sands, silica microsphere composites.

ROH

Si

Si

Si

OR

OH

X

+

OH

R Si O

R

+

HX

H2O

Phosphorus modified resin

� These resins are obtained by esterification of novolacs with phosphoric

acids or by reaction with phosphorus oxychlorides.

� These exhibit excellent heat resistance in oxidizing media.

� Outstanding flame resistance.

P ClCl

O

+

OH

CH2

OH

CH2 P

O2HCl

OO

CH2CH2

Heavy metal modified resins

� Heat and flame resistant resisns are obtained by reaction of phenol or phenolic resins with

� Metal halides like molybdenum trichloride, titanium tetrachloride,

zirconium oxy chloride, tungsten hexa chloride

� Metal alcoholates like aluminium trimethoxide, titanium � Metal alcoholates like aluminium trimethoxide, titanium

tetramethoxide.

� Metal organic compounds (acetyl acetonates).

Applications

1. Manufacturing of high temperature resistant phenolic resins.

2. Deeply coloured resins due to the presence of ionic bound metal.

Example : phenol reacted with titanium tetramethoxide gives red coloured titanium modified resins

Nitrogen modified resins

� Some polycondensation products of formaldehyde with aromatic amines

are characterized by significant stability.

� The most thermo stable materials are polycondensation compounds of

formaldehyde with p-amino phenol.

� Example : p-amino benzyl alcohol undergoes polycondensation by loss of

water.

Application

1. Production of laminates and molding compounds for electrical applications

2. High tracking resistance and favourable elecrical properties.

3. Used to modify wood and mineral fiber binder and foundry resins

CH2 OHH2N NH NH CH2 NH

Sulfur modified resins

� Direct reaction of phenols and sulfur occurs in presence of alkaline catalyst at 1300C -2300C.

� The simplest compound resulting from this reaction in dihydroxy diphenyl polysulfide which can be further reacted with formaldehyde or crosslinked with resols.formaldehyde or crosslinked with resols.

Applications

1. Manufacturing of resins with high plasticity.

2. High water solubility.

� The phenol-added vegetable oil is react with an aldehyde to form

a vegetable oil-modified phenolic resin.

� A laminate produced by impregnating paper with the vegetable

oil-modified phenolic resin and laminating and moulding the

impregnated paper is excellent in low temperature punching

quality and electrical properties and is free from low molecular

Vegetable Oil Modified Phenolic Resin

quality and electrical properties and is free from low molecular

weight components oozing out the surface of the laminate.

� Tung Oil-modified Phenolic Resin

� A Linseed Oil-modified Phenolic Resin by using a Lewis Acid

APPLICATIONS

#Automotive industry

- Tires as tackifire and reinforcing agent

- Friction and clutch facings

- Sound insulation felts

#Building and Construction industry

- Composites

- Insulation foam

- Grinding wheels and abrasive paper

# Metallurgical industry

- Foundry casting

- Refractory materials

# Paper industry

- Carbonless Copy paper

- Paper impregnation

APPLICATIONS

- Paper impregnation

#Electronical

- Coating of capacitators, resistors

- Electrical laminates

Surface Coating Application of Phenolic resins

Effective properties of Phenolic coatings

� High metal adhesion.

� Low water vapour/ oxygen transmission.

� Excellent chemical and abrasion resistance.

� Moderately high temperature characteristics.

� Curing temperature range – 160 to 2000c.

� Crosslinking at room temperature promoted by acids or pre reaction

with drying oils.

� Unmodified phenolic resins result in brittle coatings due to structural

rigidity of cured resin.

Types of Phenolic Coatings

� Automotive Coatings

� Metal container coatings

� Marine paints

Automotive coatings

� Modern automotive enamel topcoat is acrylic resin crosslinked with

MF resins

� Vehicles like maleic anhydride, epoxy ester, alkyd and acrylic resins

are crosslinked with phenolic resins for better corrosion resistance

and throwing power of the coating.and throwing power of the coating.

� Additional flexibility is provided by alkylphenols.

� The automotive under coat is applied by electrodeposition(ED) or a

variation of the “dip” operations.

� Suitable crosslinking agents for cationic electrodeposition system

include MF,UF, blocked isocyanates and phenolic resins to produce

well cured coatings.

Metal container coatings

� Metal containers like steel, chromium plated steel, tin plate,

aluminium or aluminium alloys are coated phenolic/epoxy resin

system.

� Phenolic resins are used for pails, drums, collapsible tubes,aerosol

cans and for the interior/exterior food containers.cans and for the interior/exterior food containers.

� Food stuffs containing sulphur cause black stains on the metal.

� Phenolics coatings offer excellent resistance to corrosion, chemicals

and sulfur staining compounds.

Marine coatings

� Marine paints are important for all phases of marine construction,

vessels and currently offshore oil platforms

� Shop primer- the most successful ones are based on phenolic

resin/polyvinyl butyral combination, zinc dust or aluminium/ epoxy

resin combination or zinc silicate.resin combination or zinc silicate.

� For ship repairing, primer coat based on polyvinyl butyral/ phenolic

resin/ phosphoric acid.

� Second coat consists of oil and rosin modified phenolic resins having

anti corrosive property.

Other Applications

Foam for floral arrangements

Adhesives

Floor Polish

can Coating

Toll manufacturingToll manufacturing

Printing Ink

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