④蟷
UDC 667 612 6'13:53608

卜IeasuremOnt ofヽ riscOelastic PrOperties of Coating

Fillns During the Curing Process by a Free

Damped Oscillation Ⅳlethod using a
Rigid‐ Body

Pendulum
Setti UShiama*

Abstract
A rigid‐ body llexural pendululll apparatus、 vas designed and fabricated for folloM/ing the viscoelastic

behaviOr of coating fillns during the curing process by the nleasurement of damped free oscillations
The knife‐ edge frolll whCh the pendtllum is suspended,iS imnlersed in a react,on mixture,and thechange of the viscoelastic behavior Of the specillnen brings on those of the period

りand logarithnlicdecrement(」 )ofthe damped fl・ ee oscillations of the pendulum.
The values Of rand 4 。
btained are related to the dynanlic modulus″ ノand lnodulus loss θ
7り by theお1lowing equation:

F'=(ftan θ1/わ″)[(4π 2‑」 2)/2̲M♂ /√″ "=(4π √tan θ1/bハ Z/7]

where,力 andわ are the thickness and width of the specimen,respectively and」
mass,length,monlent ofinertia,and knife‐

物:4ノ and θlare theedge angle ofthe pendulttm,respectively

Examples,including the viscOelastic behavior of acrylic‐ IIlelallline coatings duЁ ng the curing process,are shown tO illustl・ ate the useftllness of the technique.

OVeFVleWviscoelasticity of the coatillg fllin.By treating

the dynanlic response of the coating filln at

An apparatus、 vas designed and fabricated totlle rotation axis of the pendulum as the

lyleastlre the viscoelasticity of cOating fllllls

oscillation movement of the pendulum, theduringtheobtained values of r and 」 were related tO

meastlrement of damped free oscillatiOns of aequations おF the dynalllic storage modulus

rigid‐ bOdy(F)and the loss moduius(∬ う Of the cOating

f111■

the

cuFingprocessbyiexural pendlllum.IVhen a coating

is fOrmed at the rOtational axis Of thependulum andthe pendultln■ is frOely

oscillated, the oscillation period
logal・ ithlnic

ill■ .By using this llleasuremellt inethod andthese equations,the changes in viscoelasticity

r andduring the curing process of an ac巧 ″lic

decrement ∠ of the pendulum

thermosetting coating were tracked. Thechange in response to the changes inmeasuredE'characterized
Accepted on February 13,1978*Institute of ヽbcat■ onal Training

Sagamlhara,Ka12agawa

1960,

Aihara,

and

E"

were

by

changes

inclearly
curingtemperature and cross・ linker system of thecoating.
Furthermore,frona the lyleasured results of J「'and F″ it lvas possible to evaluate di]brencesthein hardness of coating fillns that differed indecrement Of the pendululyl.This nlethod has

curing temperatuFe Or fOrmulation.

some special characteristics, Firstly the use

oscillation

periodandlogarithΠ licof Oscillation analysis,to take account of the

1. Introduction

oscillation behavlor about the substrate, is

not required.

Secondly

the changes in

The rrleasurement of dynanlic viscoelasticity

viscoelasticity can be sufflciently lneasured onprovides impOrtant clues when tracking thef111■ smechanislll1 0f the curing process. Howeve葛author reports the measurelnent pFinCiples,the change in viscoelasticity during the curingapparatus and results.

ofaround only 50μ lll thickness.Here theprocess is extremel17 wide,so it is difflcult tograsp all aspects by using just a single

2.Mcasurement p五 nciples and de宙 cemeasurement method. Lewis et al.1,2, saXOn

1.Measurement p五 nciples

et al.3,Imai et al.4,5and I‐ Iirada et al.6 haVe all2‐reported the use of dynamic viscoelasticity to

Figure l shOws the knife edge of a rigid

track the curing process.

pendulunl placed on a■ at substrate surface.

In a previOus report7,the authOF inVeStigatedthe lneasurement of viscOelasticity during thecuringprocess

by

using

the

flexuralPENDULじ M

pendululn methOd.In this method,the lower
the thickness of the test piece,the lnOFe thebending of the test piece concentrates in therniCFOSCOpic areas near the flxed end and it

waspOinted

Out

that

this

Oscillation

resembles that of a pendulum.In additiOn,it
was reported that it、 vas possible to measure
the viscOelasticity fl・ om the Oscillation period

and the 10garithmic decrement,even if there
WeFe llnicroscopic local deformatiOns in such
sarnples.

Therefore the authOr ana13/zed the dynalnic

Fig. 1.

Rigid― body pendulum.

response of coatings at the rotation axis of a

At the point Of contact bet、 veen them therigid pendululln and then tried to lneasure thependulum fl・ eeサ oSCillates.Ⅵ ″hen a coatingchanges in viscoelasticity dllring the curing

material iS present between the substrate

process by using the damped fl・ ee oscillation

surface and the knife edge, as shown inofthe pendulum.As a result,it becahe clear

ndulumchanges in response to changeS in the

that

the

evaluation

Ofchangesin

Figure l, the oscillation of the pёviscoelasticity during the curing process、 ras

dyllamic properties ofthe coating fllm.

deflnitely pOssible f■・
Om the r12eagurement Of

If the pendulum in this system is displacedfl・

Om the static pOint by the swinging angle athecOating■lnl

generatesastressmodulus.Sis the cross‐ section area、 vhen tlle
coating is cOnsidered a sprillg.If the、 vidth Of

perpendicular tO the cOntact side of the knife

the flllln cOating is assumed to beedge in prOpOl・ tion to the displacement speed

expressiOn becomes A9=わ 力/sina.

and displacOllnent amount. If an OscillatiOn

ヽVhen equatiOn(2)is inser"d into equation

model, such as that shO、 vn in Figure 2, is(1),equation(1')is obtained.

considered

and

the

substrate

and

the

pendulum are jOined just like a spring , amovement equation(1)can be developed fl・め, the″ θご′ +(フ 贅 &Osa〃 sina)θ +″ メ θ=Ain ὼOm

the pOint Of view of the rOtational lnOvement(1')

ofthe pendululn at the pOint A axis.

Since equation (1') is cOnsidered as the″ θご′+2■ J1/2sina十 ルを′
θ=Jbin ωι
(1)

I:mOment Ofinelltia at the rotation axis ofthe

pendulum

equation for fl・ee Oscillation, equation (3)isfOrmed、 Ⅳhen the substitutiOns&Osah/sin6な=

κ and」 オ=コ 年iE'are lnade.
『『″ αご′チКF午 力り')θ 十力な′
θ=0

Fl:stress Of the coating f111■ Over knife edges(3)

AB and AC
力:thickness Ofthe cOating illll

a:angle formed by the knife edge ofthe staticゆpendululIIl and the substrate
卜I:mass Ofthe pendulum
ノ distance fl・ Olll rOtatiOn axis tO the center Of

gravity positiOn Ofthe pendulum

F: external force applied tO the pendulum

Fig.2. Mechanical modelof a rigid― body

pendulllm.

SWlllg″』アα,:allgular fl・ equency「hen 』ア' andヽヽ夕tilrlle

independent Of freqllency the s01utiOn Of

are assumed tO be

eqtlation(3)is given by equation(4).
lf the■ uctuatiOn angle θ is extremeb 10w,■

can be expressed by equation(2)θ=λ θ´̀′̀′r=θ )が プ‐α
)r
̀ソ

(4)

Д =」璧 &Osa・ θ(2)

By substituting this equation into equation(3),equatiOn(5)is obtained.

Here, E* is the cOmplex modulus and is′',lvhOre』 ア亜アis thè+′
modulus and Jワ ″ is the 10ss

represented by Zド =』 ア
dynallllic stOrageÌα 2‐ ″ノ
ゼリωαノチЙ白 午ゼム2フ ちリン留プ=θ『(5)

If this equation is scparated into real andWhen equation(10)is transfOrmed,4ノ /■ 2=

illlaginary ntlmbers,equations(6)and(7)areMg■ /ris obtained and therefore equation(6')

obtained.

becOmes equation(11).

」′=工船 rω みαPM誤/″

´
〔
(4五 ′

′

=2α r̀υ /χ

ク‐4五′
/■ 2]

̀2)ノ

『

(6)

F′

=(I

(11)

FuFtherllloFe,Since ∠2<<4メ ,equation(11)can be approxilnated to equation(12).

(7)

Here, Oscillation period r and logarithmic

F'=(4ノ √/鱒 [1/2‐ 1/鶴 2]

decrement」 are represented by equations(8)(12)

and(9).
In order tO measure and evaluate the relative∠ =α rchange in the viscOelasticitュ

the relative″values of F'and亜 にnameけ 』
レ′and I殆・ can be(8)

obtained 力Om equations (13)and (14)by

T=2″ /ω

setting a refbllence point.

(9)′
ル =(1/p‐ 1/鋤 2)/(1/■ 2‐ 1/η 2)

When equations(8)and(9)are substituted(13)

into equations(6)and(7),equatiOns(6')and

aF"=■ 2z/241(7')are obtained.

(14)』戸=(jイ ゆ[(4ノ ‐」2)/η ̲ンソ /1](6')

「

多 :oscillation periOd of the pendulum at thereference point

E''=411J/」 蟹P(7')∠ 1: logarithlllic decrelllent of oscillation at

the refercnce point

Next, cOnsidering the situation when the

As shOwn above,it is possible to lneasure theoscillatiOn system has no cOating lnaterial

viscOelasticity during the curing process by

between the substrate and pendulun■ , thetreating the dynalnic response of the coating

oscillation pelliod T0 0f the pendulum is given

as an oscillation lnovement ofthe pendulum.

by equation(lo).
2.2 0verview ofthe llleaSurement device
飾 =2′ 瓦 雨 筵 西Figure 3 shows the structure ofthe rlleasuring(10)

system.This nleasuring system、 vas designed

and fabricated for the purpose Of measuring

electricity tO the electromagnet

the viscOelasticity ofthermOsetting coatings⑨ automatically cOntrols the excitatio■ oftheduring the curing process.

penduluIIn and the recording ofoscillation.

The lneasurement procedure is as fo1lows.

The hotplate C)is heated by a nichrOme

On the hOtplate ③,place a test piece ② (001dheater(300ヽ 1つ ⑩.The heating temperature is■olled steel plate,20x5xO.8mm)on which

controlled by a thermistor O(TP‐the test sample ① is coated.

luchi Seieido CO.,Ltd.).A transformer ⑫ is

Next,

place the knife edge Of the rigid

used tO cOntrol the rate of temperature

pendulum ④ perpendicular tO the coating

increase. The plate temperature is recorded

surface as sho、 vn in Figure l.

by an equilibrium recorder ⑬⑥ .The til■ er

673 fl・om.

3. Deterllllination ofthe measurement
conditions

Changesinoscillation

logarithllllic decrement

periOdTand∠ of the pendulum

which occur in response tO the change inviscoelasticity Of the cOating f11ln arc affectedby the size of the pendululln (還、ス θi)and
Fig.3. B10ck diagram of the measttring system̲
l,cOated ■lm.

2.

steel substrate.

3. hot plate.

4.

pendulum.

5. probe.
6. magnetic coll.
7. detector.

shape Of the test sample(ム カ

8. oscillograph.
9. timer.
10. hcater.

measurement method,the changes in T and/

11. thcrmostat.
12. transformer.
13.

For this)、should be a,large as pOssible in Order tobest evaluate the change in viscOelasticity ofrecorder.

the test sample

After setting the pendulum, leave the test
satrlllple at room telnperature for a ixed periOd

Bysubstituting

in order to v01atilize the solvent in the test

the functiOns
ヨ[ =2/tanaand
I=T02Mg■
scosa〃 sina=ルヵ/4π 2

sample.

intO equation(12),equation(15)is obtained.

Then, begin tO heat the hOtplate andperiodically llleasure the changes in T and

TO/T=ヾ (Zb″ /Mg■ tana'+l∠of the pendulum during the curing of thesamplè(15)

Equation (15)shOws that the oscillation

The measuFelnent of oscillatiOn is sitrnilar tO

period Of the pendululln changes in responsethat previOusly reported.7

to the LctOr

Displacement ofβ b力2/』 々 光ana,

that isthe 10、 ver end Ofthe pendulum is detected bydeterlllined by b,h and E'Ofthe sample anda probe ⑤ and displacement gauge ⑦ andrecorded by the oscil10graphゝ/ith anル4ヱ and a ofthe pendulum.

electrOInagnetic pen ③ . ExcitatiOn Of theF勧り〕/Mg■ tana ≪ l it is impOssible topendulum

deternline the dynamic storage modulus Of

isperformed

byprovidingUndermeasurement

conditions

where

颯
Coloぃ r matc」 al,51(1978)

the test sample fl・ Om the OscillatiOn cycle

small and the measurement sensitivity

because r is approximately equal todecreases.

昴.

Conversely

when

the

Figure 4 sho、 vs the relatiOnship bet■ 7een 』アmeasurement conditions are sucll that theand F Of the sample tlsing equation (15).

pendulun■ is small and b″ Of thO sample isヽ
1■ en■ ,'Of the salnple decreases, rgraduallylarge,fl・ ee oscillation cOnditions are no longer

nears Zb untilthey are rlnally about the same

satisfled and the measurement is essentiallyvalue.FurthermOre,the range in、 hich theimpossible if tlle 77'Ofthe sample is large.

「

values Of r and tt become alllnOst the same

urith

it

is

depends

necessary to determine the pendululn size(」zlargelyonthemeasurement

conditions.Figure 4 shows that the larger thevaluo of the pendulum used forηmeasuroment, the larger the range of
where ris approximate取

′
』ア

this

measurement

method,4a)and sample shape(わ ,fll that matches therange in、vhich the viscoelasticity of thelneasured sample challges. Equation(15)is■.This is alsO true

used to check the lneasuremellt conditions.If

iftheね り value Ofthe measurement sample ismeasurement cOnditiOns are such that r isdecreased.

close to l%,∬ 'cannOt be calculated.Therefore,

measurement Of F′ requ,Ies measuttmente:■ 45°conditiOns 、
Ⅳhere rb/r is greater than l. In

h=50″practice, as there are some measurement
errors in tt the setup requires llleasurement

conditions such that Zb/2' is equal to or

幸

greater than l.005. This necessitates that
β惨ヵ2/躍 tana in equation(15)is equal tO or

greater

1

10・

101

108

1び
lo■
軒NAMIC MODULじ S{d"″ cmりlo0

Fig.4, RelatiOn between the period (輌 D and

than

O.01.

Accordingly

themeasurement range of F′ bシ thisdynamio mbdulus of damped free oscillationlneasurement methOd is apprO対 mated by

calculated according to Eq (15).

equation(17).

Next,exchanging the dynallllic viscOsity of thesalnple

for

η ',
夕

relationship F′

andsubstituting

the

F′

20.01Mgitana/み ″=2π η '/r into equation(17)(7)produces equation(16).

The measurement conditions arO checked

4=η '動 ″ /2∫ tana
(16)

using the relationship shown in eq■ lation(17)。

The

measurement

of

the

changeinviscoelasticity shall be performed on a coating

Logarithmic decrement∠ is determined byム
カand η'Ofthe sample alld tt rand O ofthe

f11ln having an 通 value greater than l x

pendululn.ヽ Vhen the measurement cOnditiOns

aCtual coating f111■ . If the cOnditions of theare such that the pendulum is hrge and,りpendulum used in the measurement are set"20f
the salnple is sIInall, Z becom6s extrellnely]′

lo6dyne/cln2 and a Shape that is sil■ ilar to an′

using亜 ア=l x lo6dyne/clln2,ヵ =50μ ln andみ =lcm,Mぎ tana is less than or equal t0 2.5x

the start of heating.After these 3 1ninutes thelo3も ′
ne° cm.Here,if a=45°,漁is less thancuring process begins, No change in r wasor equalto 2.6g・ cnl and the size range oftheseen during the heating‐ up stage and r、 vas

pendululn can rOughly bc deterllnined.

about equal to 3.About 3 nlinutes after thePenduluⅡ l design and prOtOtyping were done

temperature of the hOt plate reached thebased On these results.The conditions of thecuring temperatulle, 17・

prototype lⅣ ere as follows:θ i=60° ,』 √=0.9g,′」 gradually decreased during the heating‐=7.2ctFn.This pendulum had a ttb Of O.655s

stage and then cOnversely increasedヽ ″hen theand a mOment of inertia around the rotation

curing temperature、vas reached.The dOtted

axis of about 68dyne・ cm.The Oscillation ofpOl・

the prOtOtype pendulum On steel substratemeasurement range、 vhere ∠=z10.

♂

decrement zl

島 世８︒売三ェ彗３８． ︐．

4.1.Oscillation pe五 〇d r and logarithmic

Ц１１１１１１１１１１コーーーー﹁コーコー１１■■ヨ ０ー

4. Meastlrement results and observatiOns

ぴequatiOn(7).

つり２ Ｌ リト 卜ヽこ 欠Ｉ

this value was ignored when Obtaining︵ｐ ︶10garithlnic decrellnent ∠O of about o.o15 butup

tiOn of the 」 line in Figure 5 is the

可 ︱ 詐 警 澪 ギ ー ︱︒

alone due to air viscOsity and frictiOn had agradually decreased.

CUR:NG TIM=̀min}

An acrylれ therllllosetting coating was chosen

for the lneasurement sample and the changes

Fig. 5, Changes Of the period(T)and the 10gari‐thmic decrement(И )。 f epOXy modi■ d acrylic
melamine coating during the curing process.

in viscoelasticity during the curing process

The degree of curing occurring during thewere llleasured as changes in rand ∠ 。fthe

heating‐ up stage is considered tO be quite

pendulum.BefOre lneasurement,a test piecesmall.Accordingly the changes in r and z、
vas cOated and then lefL at rooln temperaturein these 3 Ⅱlinutes can be considered thefor 30 minutes.Next,a hOt plate、 vas heatedrespollses to the changes in viscoelasticity ofand the changes in rand Z were lneasured.

the sample tllat accOInpany the increase of

An example ofthe results is shO、 vn in Figure

the temperature.FurthermOre,the changes in

5.

curingrand ∠ beyOnd 3 1ninutes can be consideredtemperatutt was set at 140° C and waS kept

the responses tO the challges in viscoelasticity

for arOund 60 minutes.Thも Ineasurementthat accOn■ pany the curing ofthe sample.

In

this

lneasurement

thesalllple、 vas an acrvlic tllermosetting cOating、vhich was crOss・ linked with epoxy mOdifled

4.2 Dynamic storage modulus F′ and dynamic

melaIIline resin. The cOated thickness

sample width was O.5cm.

″『'and」σ″Figure 6 shows the changes in」
ofthe『
sample determined fl・ Om the values of r andAs shOwn in Figure 5,the temperatllre of the∠ shown in Figure 5. In this stlldy it was

sample starts"rise in the 3 minutes a■ er

difflcult tO accurately measure the fllm

■1 0f

the meastlrement sanlple、 vas 75μ m and theloss III10dlllus」

Colour matcrial,51(1978)

thickness力 at the kni偽 ‐edge pOrtiOn Of thependulum.

TherefOre,

thechangeinprocess ofthe sample.Howevet the change inviscoelasticity during the heating″ up stage

viscoelasticity、 vas denoted as a relative value

could not be llneasllred except fOr a pol・ tiOn ofusing equatiOns (13)and (14). The result

tlle change in viscosity This、vas a problem

where the standal・ d point was set at 30

caused by the llleasurement conditions.Ⅵ ア
hen

Hlinutes after the start Of heating is shOwn inaillling to measure the small changos in

Figure 6.

viscoelasticity in such a heating‐ llp process,itwill in fllture be necessally to select a biggerｂ 総 ９value of b力 2/」 %む ブtana(equation 15)than that■ 日卜く Ｊ﹂ い０エ

to measure the changes in g2.'′ sh。 、vn as the︐

３ 澤Ｂ ｏり 一卜≦ 撻︐︵ Ｐ ︶ ∝っ卜´＞轟

９ 一
ｔ コ掟 ヽ

tlsed in this study in order to increase thesensitivity Of measurement.By incFeaSing thesensitivity Of lneasurement it llnay be possible

dotted curve estilllated in Figure 6.

Next, the change in viscoelasticity indicatedby the changes in relative values as shown in

CURING TlME{rr in,

Fig. 6. ヽ√iscoelastic properties during cure of
epoxy rrlodined acrylic melamine coating
at 140° C

Figure 6、 ″as investigated in terms of」

『

′

and

″

The measurement
was cured for。C and the60̀ minutes
at 140 sample
flln■ wasIn Figure 6,the flrst 3 minutes represent theisolated.亜 rand亜 ,′ '。 f the fllln at 140° C were

heating‐ up stage and the sample viscOsity andmeasured using a RheovibFOn DD17̲II̲c00yo

elasticity decrease,In this ineasurement,theBaldwin KЮ , a diЮ ct reading dynamicchange in the viscoelasticity during theviscOelastometer.

heating‐ up stage cOllld not be measured′
fl・ equency of 3.5Hz,』ア 、
vas 4 x 108dyne/cF12

except for a pOrtion of the changes in theand F" was 9 x 106dyne/clll12 at 140

viscOsity because rwas around 76 0r

FuFthermOre,salnple tt was 68°∠ lvasAtanleasurement°

C.

C.Here,F'

around ZO as shO、 vn in Figure 5. ノゝfter 3and J′ ''11nillutes the curing prOcess started and thedynalllic viscoelastoltleter were cquated to Er′

sample宙 scOsity and elasticity increased

and EF" at 60 minutes in Figure 6 and thegreatし As seen in Figure 6, the change inchange in viscOelastlcity shown in Figure 6

viscOelasticity accOmpanying this curing was

replaced the change Of I]ノ and Iり

observed as clearly characteri2ed changes indynamic stOrage modulus shOwn in Figure 6

Er'and Er".

changOd

As mentiolled earliet the degree of curing

105dyne/cm2t。 4x108dyneた m2.The dynamic

occurring du五 ng the heating‐ llp stage isloss mOdulus is cOnsidered tO change at

considered tO be quite small.Accordingly thearound 9 x lo4dynC/cm2 t0 9 x 106dyne/cln2.

changes ln Zレ ′This shOws that the changes in viscoelasticity

and Ff・″measured fl・ om 3

measured by a direct readingin the range of around

The
5 x

1ninutes onwards as shO、 vn in Figure 6 areduring the curing procoss deternlined by thisconsidered tO represent the entire curing

IInethod are cOmparativel̲lr small.

discussed. Lfeasurement reproducibility wastlnder identical cOnditions. Reslllts Of theidentical

cOnditions,viscOelasticchanges weК slightly different,This is likeしト ロＬくコα ■０エ

under

●Ｅ

7. Although an identical sample was cured

卜くコ﹂ φっＪっ０らヽイ Ш＞一repeated lll■ easurements are shown in Figure︵Ｏｏ一口∝Ｄ く

investigated by curing an identical sample

Ｌくコ﹂即 ∽∽６コ ロ＞一

Next, measurement reproducibility 、ァ
ill beto bc the result Of slight differences in the
CURING T,M菫

curing conditions、 vhich subtly infl■ lenced theFig. 8.

{ぃ ln i

Viscoelastic propcrtiOs during cure Of

epoxy modifled acrylic mclatnine coatiligs
at various tettaperatures.
:1 ℃
0● :11伊changes in viscOelasticity during the curing

0

process.

0●

Samples were ac3″ lic thermOsetting coatings
4.3 Changes in viscOelasticity of all acrylic

based On an acrylic cOpobrlllller OfhydrOxyethyl

thermOsetting coating du五 ng the curing

metllacrylate,butyl lnethacrylate and acrylic

process

acid, Ⅵ″
ith differing compositions of cpOxy

The changes in viscOelasticity during themodifled

curing process、 vere lllleasured while changing

hexamethy101lnelallnine,

the curing temperature and the cOating

melamine,etc.

melalnine

resln,

isobutylated

fornlulatiOn Of the acrylic thermosetting︿わＦ︸ こっ Ｌく い●ヽこｗ■ りＦくコヽ ■０エ︵Ｏｏ︶ 鍼∝⊃↑く ∝︺∝ゝ面 ト ロトく コＬ 卜０■く コｗζＬくＪ一∝ ．一国 ∽ゎ 一っ Ｏ Ｏ ｔｒ ｕ＞ 一﹄一 ∽ ∽０ 一 饉＞ 一

coating.

CURING T'MI(m■)

Fig. 9̲ ヽriscoelatic properties during cure Of
cpoxy modi̲Fled aCrylic melamine coatings
at 140・ C.

o● :Acrylic/Epoxy modined melamine(70′

30 wt%)

o● :Acrylic/Epoxy modined melamine(80ノ

20wt%)

Figure 8 shows the di■ brences ill the challge
CURING TIME(min)Fig. 7.

Reproilucibility Of the measurenlents ofdynamic modulus On the same batch of
epoxy modified acrylic melattine cOatings
under the samc curing conditions,in viscOelasticity caused by val■ ‐ing the curing

temperature. The trneasurement sample、vas

an acrylic/epoxy trnodi■ ed melallnine coating(70/30%by weight).The diagram shOws thecuring reaction fOr 60 tFllinutes、Curing、 vas鰊
alllnost cOmpleted at 170 °C but was still
ヽ︼ ０∽０コ

continuing at 60 1ninutes in the case Of l10° C.

η″ith

different

resin

content. The measurement salnples、
vere

silllilar tO thOse fOr Figure 8, At a lower

melalllille resin content, the curing was

somewhat delayed and the change in thegrew

σsmallen Figure 10 and ll shOw the results for略・Ｆ

relativedynamic

storagemodulusＬヽこ ■０エ

一 いっコっ００コ ロと■くコロmelamine︵ｐし ｗ∝つたく ロエ芝整■samples＞一
卜くコ ∝Figure 9 shO、 vs the rneasurcment results of10。

Er' and EI" for cOatings formulated withvarious

types

difttrcncesofOf

hexamethOxy

IIlelallnine

E■ '

and

inethylresin,

Er''

acrylic― melaminccoatings at 140℃.

O● :Acrylic/HexalliCthoxy methyl melamineThe(75/25 wt%)

o● :Acrylic/1sめ utylated melamincレ

betweenmelaⅡ line

CURING TIME{min,Viscoelastic properties during Cure of(75/25 wt%)

andisobutylated melanline are sho、 vn in Figure
10 and the differences bet、 veen t、 vo types of

5. Conclusion

hexamethOxy methyl inelalnine l″ ith lllineralspirit tolerances(MSO ofoand O.5 are shown¨

IIllethyl lnelalnine、″as slo、 ver than thOse with

isobutylated

lnelanline

or epoxy‐ Inodi■ ed

melaFnine.Furtherllnore,when the same typeof melanline resin、 ″as used,the differences in■Ｐ ︶Ш ﹁ くこ ∝芝聾ト リヒＲコヽ■０エof the cOatings formulated with hexamethoxy

００Ｊ 晏＞Ｆ くＪ一∝ こ¨ ∽ｐ っ００巨 型 ′饉 くＪ城

in Figure ll.The results sho、 v that the curingchemical structure, expressed as differencesin MStt were associated with difbrences in

CuRING T,ME{,in}Fi3 11, Viscoelastic propertics during ctre of

the curability

acrylic― hexamethoxy methylol mclamine

coatings at 140° C.

The results shOwn in Figures 8 to ll
sufflciently

deH10nstrate

the changes

00:Mirleral spirit tolCrance 0
0● :Mincral spiHt tolerance O.5

inviscoelasticity during the curing prOcess Of

The theo=光 apparatlls and interpretation ofaCツ liC thermosetting coatings,As mentioned

resultsearliet these results shO、 v that it is possible

viscoelasticity during the curing process as a

to investigate the curing behaviOr of cOatings

dynalnic response of a coating at a pendulum

causedcoatingknitt edge still requires ftlrther discusslon.

formulations as、 vell as the curing conditions.

HOwevett this silnple method is able to detect

It is believed that the use of this methOd tO

the change in the viscoelasticity ofthe cOating

track the changes in the viscoelasticity

flllln during the curing prOces,with a highprovides useflll data fOr the elucidatiOn of the

degFee Of Sensitivity lt can also measure

curing llnechanisms of coatings.

changes in viscoelasticity using sample

bydifferences

in

the

relatedtothemeasurementofshapes silnilar to actual coatings but does nOt

38[101,424(1965)

nced oscillation analysis to take accOunt of

6. Sadao Hirata, Akira KishilnotO i C010uF

the OscillatiOn behaviOr about the substrate as

material,42[10],463(1969)is7.Setti UShiama:Colour material,51[11,lo

requiredbytraditiOnal

methOds.

FurthermOre, it is pOssible tO evaluate thecross‐ linking state fl・ OIn

the changes of thedynalnic modulus during the curing process
because the measured dynalnic lnodulus canbe cOnsidered tO lie rOughly in the rubber
elastic regiOn.This lneans that tracking thecross‐ linkingof coatings is comparat市 eけeasy
lt is believed that with fllrther investigationof lneasurexnent cOnditiOns and mechanisms,

this method can be a useil method

、ァ
ith

、
vhich tO IIneasure the viscOelasticity during

the ctlring process Over a wide measurement

range. Furthermore, it is clear that thismeasurement method can be applied not Onしto coatings, but alsO fOr cOmparatively large

samples such as putty adhesive and cement
nlaterials.

Acknowledgelnents
The authOr wishes tO thank Takeyuki Tanaka
of Nippon Oil and Fats Co.,Ltd.fOr help andto thank

Nippon Oil and Fats Co.,Ltd.fOr prOviding
measurelnent samples.

References

l.A.R Lewis,J.K.Gillham:J■ p■̲fbみ 切 θF
Sd.,6,422(1962)
2.」 .K.Gillham,A.ユ
Sci、

Lewis:Jノ 筆P′ fbみ η θr

,7,685(1963)

3.R.Saxon,ユ C.Lestienne:J効 ′ 晨 ン″α・9ィSci̲,8,475(1964)
4.Takeo lmail C010ur material,38[2],80(1965)
5.TakeO Imai,TOshiO okawa i C016ur material,(1978)