Manufacture of Alkyd Resin from Castor Oil

 
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World Academy of Science, Engineering and Technology 48 2008

            Manufacture of Alkyd Resin from Castor Oil
                                                   Nway Nay Hlaing1, Mya Mya Oo2

                                                                               endless use of the article of manufacture. The industrial
   Abstract— Oil-modified alkyd resin was prepared from                         finishes include primers and top coats for refrigerators,
crude castor oil. The experiment started with investigating the                 furniture, and electrical equipment. In view of the
optimum conditions for neutralization of crude castor oil and                   development of these items and sectors, the positive growth is
bleaching of neutralized oil. Then the characteristics (iodine                  expected for paint industry [2].
value, viscosity, acid value, refractive index and color) of oils                         Further the paint industry envisages a future
were determined. Refined oil has iodine value of 90,                            expansion in view of development in Automobile Industry,
kinemetic viscosity of 4 St, free fatty acid value of 1,                        utility in Nuclear Power Station, development in Corrosion
refractive index of 1.474 and color number of 8. These results                  Resistant Coatings, expansion in housing activity and other
showed that the refined oil was qualified to prepare                            industry uses. The demand of alkyd resin being an ingredient
dehydrated castor oil. Dehydration of refined oil was carried                   in Paint, Varnish and Printing ink industry would be linked
out at 210-220˚C under 600-640mmHg with the help of 1%                          with the Paint industry.
(wt%) NaHSO4 catalyst. The dehydrated castor oils were                                    There are many significant efforts that have been
analyzed for iodine value, viscosity and its set to touch time                  made to increase alkyd resin production. Many researchers
and drying time were also investigated. Dehydrated castor oil                   have attempted to search the different sources for alkyd resin
has iodine value of 140, kinemetic viscosity of 1.6 St, set to                  preparation. Airegumen I Aigbodion et al [3] studied
touch time of 4 hr and drying time of 5 days. And then , oil                    enhancing the quality of alkyd resins using methyl esters of
modified alkyd resin (acid value 6.6) was prepared from                         rubber seed oil in 2004.
dehydrated castor oil by alcoholysis method in excess of                                  A lot of alkyd resins were imported to Myanmar
glycerol and phthalic anhydride in the presence of 0.3% (wt%)                   Paint Industries every year. In order to save foreign currency
NaOH catalyst. The obtained resin was characterized by                          outflow, it is needed to produce alkyd resin in Myanmar.
Fourier Transform Infrared Spectrophotometer (FTIR) and the                               The oils that are mostly employed for alkyd resin
properties were determined.                                                     synthesis are linseed oil, soybean oil, dehydrated castor oil,
                                                                                fish oil and tall oil. Myanmar being rich in aquatic and
                                                                                terrestrial resources, every state and division is pursuing the
  Keywords— Alcoholysis method, Alkyd resin, Castor oil,                        target of putting 500,000 acres under physic nut (castor oil) in
Dehydrated castor oil, Polymerization                                           three years. Rural development tasks are included in the
                                                                                national development endeavors that are being carried out by
                        I.   INTRODUCTION                                       the Nation target.
         Polymerization is one of the most important                                      Castor oil is useful directly in protective coatings as a
industrial processes. Resins and emulsion are two main classes                  plasticizer in alkyd systems, and blown castor oil is an
of polymer. Alkyd resins are by far the most important class                    important nitrocellulose plasticizer. In commercial
of coating resins. It is estimated that alkyd resins contribute                 manufacture of dehydrated castor oil, the aim is to produce the
about 70% to the conventional binders used in surface coating                   most valuable material for use as a drying oil. By far the most
today. The popularity of alky resins as vehicle for coatings is                 important coatings use of castor oil is in the form of
largely due to their unique properties such as film hardness,                   dehydrated castor. Dehydrated castor oil is now recognized as
durability gloss and gloss retention, resistance to abrasion, etc.              an individual drying oil with its own characteristic properties
impacted on them through modification with drying oil [1].                      and advantages. The drying oils owe their value as raw
         Alkyd resins are used in both clear and pigmented,                     materials for decorative and protective coatings to their ability
industrial and trade coating to protect and decorate a wide                     to polymerize or “dry” after they have been applied to a
variety of substances. The industrial coatings or finishes                      surface to form tough, adherent, impervious, and abrasion
generally are applied during the manufacturing process of the                   resistance films. The advantages claimed in surface coating
item which they cover. Often they are specifically formulated                   applications include excellent odor and heat bleachability,
to meet both conditions desired for their application and the                   good drying properties, more uniform polymer structure, and
                                                                                lack of after-yellowing. The dehydrated castor oil is non-
                                                                                yellowing oil and so this can give requirements of coating
   1.Department of Chemical Engineering, Mandalay technological                 industries [2,4,5,6,7].
University, Patheingyi Township, Mandalay, Myanmar, Myanmar 11011, e-
mail: nway.nay5@gmail.com
   2.Yangon Technological University, Gyongone, Insein, Yangon, Myanmar         2. Materials and Methods
11011, e-mail : most7@gmail.com                                                 2.1. Neutralization of Crude Castor Oil

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          Oil (100g) was heated to 55˚C. Then, the calculated
amount of strong (45˚Be, 2N NaOH) lye was added to
neutralize the free fatty acids exactly, with constant stirring.
Completion of neutralization reaction was determined by
testing the mixture with phenolphthalein indicator. When the
indicator color of the sample mixture turned to pink,
neutralization was completed. Then NaCl solution was heated
to 90˚C and 20ml of hot NaCl solution was added to the                        Figure 2.1.Dehydration of Castor Oil
mixture to ensure adequate salting or graining out of
soapstock. After that the mixture was poured into separating             2.4. Preparation of Alkyd Resin
funnel. Three hours later, the mixture was separated into two                      Oil modified alkyd resin was prepared with
distinct layers. Then the lower layer or soap layer was drain            dehydrated castor oil, glycerol and phthalic anhydride using
out. The upper layer or oil layer was washed with hot water.             NaOH catalyst. The preparation was done in a 4-neck round
Washing was carried out until color of phenolphthalein                   bottom flask fitted with a motorized stirrer, a nitrogen inlet, a
indicator did not change to pink. After complete washing, the            thermometer pocked and a hold for sampling. The system was
oil was dried at 100˚C in oven to evaporate the moisture.                shown in Fig. 2. In the preparation of alkyd resin, two stages
Drying and cooling was carried out until the weight of dried             were involved. The first stage was alcoholysis stage and the
oil remained unchanged.                                                  second stage was esterification stage.
          The neutralized oils were weighed to calculate oil                 Raw material                   Weight (g)       Weight (%)
loss and then their free fatty acid content (FFA) were                       Dehydrate      castor    oil 114.27             60.437
determined [8]. The characteristics of crude oil and                         (DCO)
neutralized oil were determined by American Society of                       Phthalic anhydride (PA)        43.364           22.935
Testing and Materials (ASTM) standard methods.                               Glycerol (G)                   31.44            16.63
                                                                             Total                          189.074          100
2.2. Bleaching of Neutralized Oil
   The neutralized oils were heated to 100˚C and different               Stage 1 (alcoholysis): In this stage, monoglyceride was first
amounts of activated charcoal were added. After the mixture              prepared by reacting the oil with glycerol. Alcoholysis of oil
was stirred for 45 minutes, the mixture was cooled to room               was carried out with different percentages of (0.03%, 0.05%,
temperature and activated charcoal was removed by filtering              0.1%) (by weight) PbO catalyst and (0.1%, 0.2%, 0.3%)(by
with filter paper.                                                       weight) NaOH catalysts.
          The neutralized oils were also bleached with different                   In alcoholysis reaction, the oil was heated with
amounts of bentonite and a mixture of activated charcoal and             agitation speed of (700 rpm) and N2 sparging rate of about
bentonite (1:1 ratio). Then the process was carried out above            (0.06ft3/sec) to 230-240˚C. Glycerol and selected catalyst was
procedure.                                                               added and alcoholysis reaction was carried out at 230-240˚C.
          The colors of bleached oil samples were determined             The reaction was continued until a sample of the reaction
by a spectrophotometric method [11]. In this method, optical             mixture became soluble in two to four volumes of anhydrous
densities were measured at the wavelength of 460nm, 550nm,               methanol. After alcoholysis reaction was completed, the
620nm and 670nm. Then the photometric colors were                        reaction mixture was cooled to 140˚C.
calculated by the following equation.                                    Stage 2 (esterification): In this stage, phthalic anhydride was
Photometric color = 1.29D460 + 69.7D550 + 41.2D650 –                     added to the monoglyceride mixture. The temperature was
                               56.4D670               [4]                maintained at the range of 230-240˚C and maintained at this
                                                                         temperature. The sparging rate of N2 was increased to
2.3. Dehydration of Castor Oil                                           (0.1ft3/sec). The reaction was monitored by periodic
                                                                         determination of the acid value of the mixture until acid value
   Bleached oil (50g) and 2% (wt%) of NaHSO4 catalyst were               dropped to nearly 5.
placed into round bottom flask and the apparatus was set up as              The acid value of alkyd resin was determined by ASTM D
shown in figure (1). The system was heated to 210-220˚C for              1639-90 and the chemical resistances also determined. The
dehydration time were taken for 15, 30, 45, 60, 75 minutes.              prepared resin was standardized by FTIR [12, 13].
         Dehydration was also carried out under 600-640
mmHg (vacuum) as described in the above process. In this
process, the effect of NaHSO4 catalyst amount on the
properties of dehydrated castor oil was also investigated.
         Then, the iodine values of dehydrated castor oil were
determined by ASTM D1541-86 and viscosities were
determined by ASTM D 1545-63 method. The drying time
and set to touch time were also determined by ASTM D 1953-
70 [9].
                                                                              Fig.3.3.Alkyd Resin Preparation

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World Academy of Science, Engineering and Technology 48 2008

                                                                         Bleaching time                 = 45 minutes
3. Results and Discussion                                                *Photometric color = 1.29D460 + 69.7D620 + 41.2D650 í
3.1. Results                                                               Sample Bleaching (wt%) of Photometric                Wt. of
3.1.1. Characterization of Crude Castor Oil                                  no.         agents    bleachin       color       Refined oil
         The characteristics of crude castor oil are shown in                                      g agent       number           (g)
Table 3.1.                                                                   A1        Activated       3           7.25        57.437
Table 3.1. The Characteristics of Crude Castor Oil                           A2         charcoal       5           6.35        57.400
Characteristics                  Crude castor oil                            A3           (A)          7           7.16         57.36
Free fatty acid value                          19                            A4                        9           8.32        57.254
                                                                             A5                       11           9.29        57.217
Color, photometric                             -                             B1        Bentonite      3            3.80        58.118
Refractive index                               -                             B2           (B)         5            3.40        57.386
                                                                             B3                       7            4.40        57.380
Specific gravity                               0.9633                        B4                       9            4.47        57.311
Viscosity(Stroke)                              4.5                           C1        Activated      3             4.0        57.405
                                                                             C2         charcoal      5             3.0        57.342
Iodine value, wiji’s                           89.5
                                                                             C3           and         7            4.46        57.254
                                                                                       bentonite
3.1.2. Neutralization of Crude Castor Oil                                              (1:1 ratio)
          Table 3.2 show the FFA content of neutralized oil.                              (C)
Initial weight of crude castor oil = 100g                                56.4D670 [4].
FFA (%) of crude oil               = 19%
 Neutralization temperature        = 55˚C                                3.1.5. Dehydration of Refined Castor Oil
20% NaCL solution                  = 40ml                                         Table 3.5 present the yield of dehydrated castor oil at
Sr. 2N           Neutralization FFA (%)         Weight of                different dehydration conditions. The changes of iodine value
no NaOH time(minutes)              of          Neutralized               and viscosity by dehydration of castor oil at different
                                   Neutralized oil (g)                   dehydration conditions are shown in Fig. 3.1 and Fig. 3.2.
                                   oil
1      15.2      5                 8.448       65.09                     Table 3.5. Yield of Dehydrated Castor Oil at Different
2      30        10                0.987       60.43                     Dehydration Conditions
                                                                         Initial weight of sample C2 = 50g
3     30           10              0.988              51.79

4.1.3. Characterization of Refined Castor Oil
     The characteristics of refined castor are described in
Table 3.3 by comparing with ASTM standard castor oil.
Table 3.3.Characteristics of Refined Castor Oil
Characteristics           Refined          Castor oil
                          castor oil       (ASTM D 960-79)
Free fatty acid value     1                1.00
Color, photometric        8                -
Refractive index          1.474            1.476 to 1.4778
Specific gravity          0.9614           0.957 to 0.961
Viscosity(Stroke)         4                6.3 to 8.9
Iodine value, wiji’s      90               83 to 88
Source [6]
3.1.4. Bleaching of Neutralized Castor Oil
    Effect of bleaching on color and yield of neutralized castor
oil is shown in Table 3.4. Oil was bleached with 0-11% of
activated carbon, 0-9% of bentonite and 0-7% of 1:1 mixture
of activated charcoal and bentonite
Table 3.4. Effect of Bleaching On Color and Yield of
Neutralized Castor Oil
Initial weight of neutralized oil = 100 g
Bleaching temperature             = 100˚C

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                                                                                                                                                                                    NaHSO4                  V.P        Dehydration time (minutes)/Yield (%)
                                                                                                                                                                                    catalyst               (mm
                                                                                                                                                                                    (%)                    Hg)
                                                                                                                                                                                                                        15          30         45       60      75
                                                                                                                                     um
                                                                                                                                          )                                         2                      760         0.5         90.37      89.88    89.56   89.55
                                                                                                                                cu
                                                                                                                    ,      va
                                                                                                             m   Hg
                         140                                                                        0m                                                                              2                      600-        90.9        90.11      89.5     89.13   89.06
                                                                                             -6 4
                                                                                  (60
                                                                                      0
                                                                                                                                         u      m)                                                         640                                           5
                                                                                                                                     acu
                         135                                                O
                                                                     HS
                                                                                  4
                                                                                                                                ,v
                                                                Na                                                         Hg
                         130                            2%                                                 0      mm                                                                1                      600-        90.2        90.035     89.67    89.39   89.28
                                                                                                  0   -6 4
                         125                                                        (60
                                                                                 SO 4
                                                                                                                                                                                                           640
 Iodine Value

                                                                             H
                                                                      Na
                         120                                    1%

                         115
                                                                                                                                                                                    1
                         110                                                                       ho                      ut vac
                                                                                                                                  uu          m)                                     dehydration with 1% NaHSO4 catalyst for 60 minutes
                                                                                        S O 4(w it                                                                                  2
                                                                            2    % N aH                                                                                              dehydration with 2% NaHSO4 catalyst for 45 minutes
                         105

                         100
                                                                                                                                                                                    3.1.7. Preparation of Alkyd Resin
                                                                                                                                                                                             Reaction condition of alcoholysis reaction condition
                                10            20                 30                      40                           50                  60             70        80
                                                                            Dehydration Time(min)                                                                                   in alkyd resin preparation is described in Table 3.7. Fig. 3.3
                                                                                                                                                                                    shows the acid value control of esterification reaction. Yield
                                                                                                                                                                                    of dehydrated castor oil-modified alkyd resin and the
Fig. 3.1.Change of Iodine Value with Reaction Time                                                                                                                                  calculation for percentage of reaction complection are
          for Dehydration Temperature at 210-220˚C                                                                                                                                  presented in Table 3.8. The appearances of gel type resin,
                                                                                                                                                                                    dehydrated castor oil-modified alkyd resin are shown in Fig.
                                                                                                                                                                                    3.4.
                                                                                                                                                                                    Table 3.7. 1st Stage Alcoholysis Reaction Conditions
                                                                                                                                                                                    Reaction temperature = 230-240˚C
                                     2%
                                          Na
                                                                                                                                                                                    Agitation speed        = 500 rpm
                                                                                                                                                                                                          = 0.06 ft3/minutes
                         4 .6
                         4 .4
                                               HS
                                                    O       4   (w
                                                                     it h
                                                                                                                                                                                    N2 sparging rate
                         4 .2                                               ou
                         4 .0
                                                                                 tv
                                                                                    ac
                                                                                         uu
                                                                                                                                                                                      Alcoholysi      Catalyst   Reaction    Completion of
                         3 .8                                                                  m
                         3 .6
                                                                                                    )                                                                                 s catalysts    % (wt%) time (hr)         alcoholysis
     Viscosity(Stroke)

                         3 .4
                         3 .2
                                     2%
                                          N
                                                                                                                                                                                                                                reaction*
                         3 .0                 aH              1%
                         2 .8
                                                   SO
                                                        4   (6
                                                               00
                                                                   Na
                                                                       HS
                                                                                                                                                                                          PbO          0.03          4        Not complete
                                                                  -6      O                  (6
                         2 .6
                         2 .4
                                                                     40
                                                                        m
                                                                                         4
                                                                                                  00
                                                                                                        -6
                                                                                                             40
                                                                                                                                                                                                       0.05          4        Not complete
                                                                          m                                           m
                         2 .2
                         2 .0
                                                                                      Hg
                                                                                              ,v
                                                                                                                          m
                                                                                                                              Hg
                                                                                                                                   ,v
                                                                                                                                                                                                        0.1          4        Not complete
                                                                                                 a      cu                            ac
                         1 .8
                         1 .6
                                                                                                             um
                                                                                                                  )
                                                                                                                                           uu
                                                                                                                                                m
                                                                                                                                                    )
                                                                                                                                                                                         NaOH           0.1          4        Not complete
                         1 .4
                                10             20                       30                        40                          50                    60        70        80                              0.2          4        Not complete
                                                                                 D e h y d r a t io n T im e ( m in )
                                                                                                                                                                                                        0.3          2          complete
                                                                                                                                                                                    *It was determined by testing the solubility of alcoholysis
Fig.3.2. Change of Viscosity with Reaction Time                                                                                                                                     mixture in anhydrous methanol.
        for Dehydration Temperature at 210-220˚C

4.1.6. Characterization of Dehydrated Castor Oils
                                                                                                                                                                                                         100
         The characteristics of typical dehydrated castor were
presented in Table 3.6 by comparing with ASTM standard
                                                                                                                                                                                            acid value

dehydrated castor oil.
                                                                                                                                                                                                         10
Table 3.6.Characteristics of Typical Dehydrated Castor Oils
Vacuum pressure = 600-640 mmHg
Characteristics Dehydrated Dehydrated Standard                                                                                                                                                            1
                   castor oil1    castor oil 2 dehydrated                                                                                                                                                         30          60         90      120     150
                                               castor oil
                                                (ASTM                                                                                                                                                                    reaction time (minutes)
                                               D961-86)
 Iodine value        140.01         139.05       125-145                                                                                                                                Fig.3.3. Acid Value Control of Esterification Reaction
     Viscosity                                                                   1.600                                                1.686                         1.5-1.8
                                                                                                                                                                                    Table 3.8. Yield of Dehydrated Castor Oil-Modified Alkyd
      (Stroke)
                                                                                                                                                                                    Resin
    Set to touch                                                                      4                                                       3.5              2.5,approxi
    time (hour)                                                                                                                                                  mately
    Drying time                                                                       5                                                        5                    -
       (hour)

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World Academy of Science, Engineering and Technology 48 2008

I.W-initial weight                                                       DCO        I..W(g)   F.W     Y         IAV       FAV     P
F.W-final weight                                                         alkyd                (g)     (%)                         (%)
Y-yield                                                                  resin
IAV-initial acid value                                                   (100%                                            6.6     97.72
FVA-final acid value                                                     solid)     189.58    140     73.85     298.58
P-degree of reaction complection                                                    2                           8
                                                                         5
                                                                                  1125.26           1150-1060

                                                                                                                   O=C-O-C-
3.1.8. Characterization of Alkyd Resin
   The physico-chemical properties of alkyd resin are
presented in Table 3.9. The chemical resistances of alkyd resin
film are shown in Table 3.10. Table 3.11 show FTIR
absorption band of dehydrated castor oil-modified alkyd resin.          3.2. Discussion
                                                                        3.2.1. Discussion on Characteristics of Crude Castor Oil
Table 3.9. Characteristics of Dehydrated Castor Oil-modified               According to Table 4.1 FFA content of crude castor oil
Alkyd Resin                                                             was high and it was not within the ASTM specification limit.
Properties     DCO           RSO alkyd DCO                              The color and refractive index of crude oil can not be
               alkyd         resin*       alkyd                         determined because the transparency of crude oil was very
               resin                      resinŠ                        poor. The viscosity of crude oil was slightly lower than that of
Acid value     6.6           12.7         4-11                          ASTM standard oil [6]. Even though, the specific gravity and
Iodine         80.24         66.3         -                             iodine value of crude oil were in the range of ASTM
value                                                                   specification limit, the FFA content of crude oil was differed
Color          Yellow        Brown        -                             from ASTM standard. The only reason to reduce the FFA
Refractive     1.477         1.5050       -                             content of oil was to neutralize the crude oil.
index
Gouge          HB            HB           -                             4.2.2. Discussion on Neutralization of Crude Castor Oil
hardness                                                                          In neutralization process, it was found that 30 ml of 2
Scratch        F             H            -                             N NaOH per 100g of oil was required to obtain neutralized oil
hardness                                                                with an acceptable FFA content and to be a minimum of oil
RSO- rubber seed oil                                                    loss. The neutralization time of 10 minutes was sufficient to
Source [1, 14]                                                          reduce FFA content from 19% to 1%. In neutralization of oil,
                                                                        free fatty acid content of oil was converted in oil soluble
Table 3.10. Chemical Resistances of Alkyd Resin Films                   soaps. Small amount of impurities such as phosphotides,
     Media         Immersion          Appearance of                     proteins or protein fragments, and gummy or mucilaginous
                  time (hours)             film*                        substances were also removed by neutralization process.
                                                                        Therefore, the initial weight of oil was decreased as well as
Distilled water         18               Not effect
                                                                        the yield of oil was decreased. In neutralization process, there
                         8               Whitening
                                                                        was a difficulty to separate the soap and oil layer because FFA
  3 N NaOH              16               Blistering
                                                                        content in crude oil was very high. The two layers can be
                        24                Removal
                                                                        easily separated when NaCL solution was added to the
*It was examined after the films were air dried for 30 minutes.         neutralized mixture because NaCL can help to ensure
                                                                        adequate salting or graining out of the soapstock. Other
Table 3.11. FTIR Absorption Band of Dehydrated Castor Oil-              impurities in oil were removed by washing with hot water. In
Modified Alkyd Resin                                                    washing step, there has a little loss of oil. So, the average
 Band Experimental Literature         Remark                            yield of oil was 64%.
 No.     frequency      frequency
         (cm-1)          (cm-1)                                         3.2.3. Discussion on Characteristic of Neutralized Castor Oil
 1       3008.99        Near 3030     =C-H                                 From Table 3.3., it can be seen that the neutralization
         2926.74                                                        process can reduce the FFA content of crude oil from 19% to
 2       3514.21        3570-3200     O-H                               1%. Then, it can give the refined oil color of 8 and refractive
         1169.21        Near 1100     O-H                               index of 1.474. Therefore, neutralization process can offer
 3       2855.67        2926-2850     C-H                               great effect on FFA content, color and refractive index of oil.
         1460.43        1485-1440     CH2                               Moreover, the refined oil has specific gravity of 0.9614,
 4       1738.64        1750-1735     CH3COOCH3                         viscosity of 4 and iodine value of 90. These results were
                                                                        nearly the same as that of the crude oil. Although the
          1730.30         1730-1717           COO
                                                                        neutralization technique reduced significantly FFA content in

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World Academy of Science, Engineering and Technology 48 2008

oil, it gave slightly effect on specific gravity, viscosity and            4.2.6. Discussion on Characteristics of Dehydrated Castor Oils
iodine value of oil.                                                          The iodine value and viscosity control the extent of reaction
                                                                           and set to touch time and drying time show the drying
3.2.4. Discussion on bleaching of neutralized oil                          properties of dehydrated castor oil. Table 4.7 described that
     In Table 3.4, it can be seen that the highest color removal           the iodine value and viscosity of dehydrated castor oils were
efficiency was obtained by bleaching with 5% of bleaching                  in the limit of ASTM standard dehydrated castor oil. Then the
agents. 5% of activated carbon, 5% of bentonite and 5% of                  drying time and set to touch time also gave satisfactory result.
(1:1) mixture of activated charcoal and bentonite can give the             Therefore, these dehydrated castor oils were acceptable to
oil with photometric color of 6.35, 3.4 and 3.0 respectively.              prepare drying oil-modified alkyd resin.
Bleaching with (1:1) mixture of activated charcoal and                     4.2.7. Discussion on Preparation of Alkyd Resin
bentonite can offer better result. So, it can be chosen as                           According to the literature [3], the alcoholysis
bleaching agents in bleaching of neutralized oil.                          reaction is usually completed within an hr or two hrs after the
   Beside decoloring, bleaching of neutralized oil served the              batch had reached operating temperature. In Table 4.8, it was
important function of largely removal of trace amount of soap.             found that the samples of the alcoholysis mixture did not
After bleaching process, the average oil yield was 69%. The                completely soluble in anhydrous methanol although the
oil yield was decreased during the bleaching process due to                alcoholysis reactions were carried out for 4hr by using
the adsorption of oil on the surface of adsorbents and the                 different amount of litharge catalysts (0.03%, 0.05%, 0.1%)
filtration of oil with filter paper.                                       and NaOH catalysts (0.1%, 0.2%). It should not be tried to use
                                                                           the amount of PbO catalyst more than 0.1% (wt%) because the
4.2.5. Discussion on Dehydration of Castor Oil                             preferred PbO catalyst percent for alcoholysis reaction is 0.01-
          According to the Table 3.5, the yield of dehydrated              0.1 in literature. Then, large quantities of catalyst lead to dark
castor oil decreased with increasing the dehydration time.                 the color of alkyd resin and detract from the water and alkali
Then, there was a slightly different in yield of dehydrated                resistances of alkyd resin. In alcoholysis of oil with 0.1%
castor oil although the dehydration process was carried out                (wt%) and 0.2% (wt%) NaOH catalyst, it cannot also give
different dehydration conditions.                                          complete alcoholysis mixture after reaction was carried out for
          In Fig. 3.1 and 3.2, it was observed that the                    2 hrs. The degree of alcoholysis has an important bearing on
dehydrated castor oil with a maximum iodine value and a                    the properties of the resulting resin. During the final reaction
minimum viscosity could be obtained at the proper reaction                 with phthalic anhydride, esterification of the free hydroxyl
time. The iodine values of dehydrated castor oil increased                 groups of the monoglyceride must compete with any
with the reaction time and reached a maximum value. Then, it               unreacted or excess glycerol. The latter reaction leads to
decreased because prolong heating leads to polymerization                  glyceryl phthalate which is insoluble in the oil-acid-glyceryl
with a consequence drop in iodine value and a step rise in                 phthalate and unreacted glyceride oil. Unless sufficient
viscosity. The minimum viscosity occurs at or near the point               monoglyceride is present prior to the addition of the phthalic
of maximum iodine value.                                                   anhydride, the reaction product will be unsoluble gel of
          From Fig. 3.1, the dehydration of oil without vacuum             glyceryl phthalate suspended in oily mixed glycerides. Such a
system could not give acceptable iodine value to qualify as                product is worthless.
drying oil because the iodine value of oil was below 125 (the                        In esterification reaction, it was observed that the
lower limit of ASTM dehydrated castor oil) . In this process, a            longer the reaction time, the more viscous the mixture is. In
lot of fumes were evolved during dehydration of oil and these              this stage, adequate agitation was necessary for complete
fumes were condensed and dripped back into the dehydrated                  mixing of monoglyceride mixture and phthalic anhydride.
oil. It was undesirable effect. Therefore, it is required to use a         Unless adequate mixing was supplied in this stage, the
current of inert gas such as carbon dioxide or nitrogen in order           unqualify alkyd resin would be resulted. So, the N2 sparging
to remove the decomposition products. The most effective                   rate was increased in order to remove liberated reaction
way of removing of fume is by using the vacuum pressure. By                product and to increase the heat and mass transfer of chemical
this means, the problem of condensing the fume into the                    reaction. In Fig. 3.3, the oil-modified alkyd resin with acid
dehydrated oil was largely avoided. Therefore, dehydration of              number of 6.6 was obtained after the esterification reaction
refined castor oil was carried out under vacuum system.                    was carried out for 150 minutes. It should not try to proceed
When dehydration of oil was done by using 1% of NaHSO4                     the reaction after the acid number of alkyd resin had dropped
catalyst and vacuum pressure of 600-640 mmHg and the                       to 6.6 because the reaction was closed to gel point.
optimum reaction time is 60 minutes, this system could give                          In Table 3.8, it was observed that 97.72 % of reaction
dehydrated castor oil with iodine value of 140. When                       was completed when the final acid number of alkyd resin was
dehydration of oil was done by using 2% of catalyst and                    6.6. Then, the yield of alkyd resin was 73.87%.
vacuum pressure of 600-640 mmHg and the optimum reaction
time is 45 minutes, this system could give the dehydrated                  3.2.8. Discussion on Characteristics of Alkyd Resin
castor oil with iodine value of 139.05. Although the                          In Table 3.9, there is no common standard to compare
dehydration time was decreased with increasing the amount of               alkyds resins. Each alkyd resin has its own properties. The
catalyst percent, the refractive index of the dehydrated oil was           alkyd resin that has acid number of less than 15 is suitable for
increased.                                                                 application of paint, according to literature [1, 7, 8]. The
                                                                           scratch hardness of alkyd resin was F and gouge hardness was

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World Academy of Science, Engineering and Technology 48 2008

HB. The refractive index of alkyd resin was 1.447 and color
was yellow.
                                                                        [1]Patton, T.C. 1962. Alkyd Resin Technology. NewYork:
4.2.9. Discussion on Chemical Resistance of Alkyd Resin                 Interscience Publishers, Inc. A Division of John Wiley and
Film                                                                    Sons, Inc.
   The resistance of alkyd film was determined in two media,
distilled water and NaOH solution. Table 3.10 described that            [2] Waters, R.T. Resins-Synthetic, Alkyd Resins. Section 2.
there was no effect on alkyd film after immersion in distilled          London: Wyman and Sons, Ltd. 1955.
water for 18 hours. The immersion of alkyd film in water for
18 hours was sufficient time to examine the water resistance.            [3] Ikhuoria, E.U., Aigbodion, A.I., and Okieimen, F.E.
When the alkyd film was immersed in strong alkali solution,             “Enhancing the quality of Alkyd Resins Using Methyl Esters
3N NaOH, the film got whitening after immersion time for 8              of Rubber Seed Oil”. Tropical Journal of Pharmaceutical
hours, blistering after immersion time for 16 hours and                 Research. 3 (No.1): 2004, 311-317.
removal after immersion time for 24 hours. So, these results
show that the prepared alkyd resin has high chemical                    [4] Formo, M.W. et al. Bailey’s Industrial Fats and Oils
resistance.                                                             Products. Vol 1. 4th Edition. New York: John Wiley and
                                                                        Sons, Inc, 1965.
4.2.10. Discussion on FTIR Adsorption of Dehydrated Castor
Oil-Modified Alkyd Resin                                                [5] Kirk, R.F and Othmer, D.F. Alkyd Resin: Encyclopedia
   The FTIR spectrum of prepared alkyd resin exhibits a                 of Chemical Technology. Vol 9. New York: John Wiley and
characteristic of straight chain ester band at 1738.64 cm-1 and         Sons, Inc, 1947.
aromatic ring ester band at 1730.09 cm-1. The present of O=C-
O-C- also exhibit a characteristic ester band at 1125.26 cm-1.
The appearance of CH2, -CH- confirms the present of methyl              [6] Mark, H.F. Alkyd Resin: Encyclopedia of Polymer
group at 1460.43 cm-1 and 2856.67 cm-1. The adsorption band             Science and Technology. Volume 1. New York: Interscience
at 3008.99 cm-1 is characteristic of alkene carbon (=C-H)               Publishers. A Division of John Wiley and Sons, Inc, 1964.
according to literature [12, 13].
                                                                        [7] Mark, H., Proskauer, E.S., and Frilette, V.J. Resins,
4. Conclusion                                                           Rubbers, Plastics Yearbook. New York: Interscience
          The characteristics of refined castor oils were found         Publishers, Inc. A Division of John Wiley and Sons, Inc,
to be standardized with ASTM standard castor oils and it was            1954.
suitable to carry out the next step. The refined castor oil was
done by using NaHSO4 catalyst to carry out the dehydration               [8] Mehlenbacher, V.C. Official and Tentative Methods for
process. Dehydration under vacuum pressure system was                   the American Oil Chemists’ Society. Second Edition.
effective processing method and this pressure influenced the            American Oil Chemists’ Society (AOCS). Chicago: 35 East
quality of dehydrated castor oil. A typical dehydrated castor           Wacker Drive, 1950.
oil (iodine value 140, viscosity 1.6 stroke, set to touch time
3.5 hr and drying time 5 day) was prepared with 1% NaHSO4               [9] Anonymous. Annual Book of American Society for
catalyst under vacuum of 600-640 mmHg at 210-220˚C. In                  Testing and Materials (ASTM). Part 27, 1975.28, 29. USA.
alcoholysis of oil by using 0.3% (wt%) NaOH catalyst, it gave           .
complete alcoholohysis mixture to preceed the esterification
reaction after reaction time for 2 hrs. Dehydrated castor oil           [10] Pecsok, R.L. Methods of Chemical Analysis. Second
has been used in the preparation alkyd resin. Dehydrated                Edition. New York: Interscience Publishers, Inc. John Wiley
castor oil-modified alkyd resin (acid value 6.6) was prepared           and Sons, Inc, 1980.
by alcoholysis method from dehydrated castor oil, glycerol
and phthalic anhydride with a help of 0.3% NaOH catalyst.               [11] Branch, R.F. Application of Infraced and Ultraviolet
The physico-chemical properties and high chemical resistance            Spectra to Organic Chemistry: Practical Organic Chemistry,
of alkyd resin film showed that they were promising in                  1946.
formulating of paint.
                                                                        [12]     Grasselli, J.G., Mocadlo, S.E., and Mooney, J.R.
Acknowledgements                                                        Applied Polymer Analysis and Characterization, Analysis
   The financial support of Ministry of Science and                     of Polymers by Fourier Transform Infrared Spectroscopy.
Technology is gratefully acknowledged. The author wishs to              Vol. 2. New York: Oxford University Press.
extend her gratitude to Prof. Dr. Mya Mya Oo for stimulating
discussion.                                                             [13] Sanler, S.R. et al. Polymer Synthesis and
                                                                        Characterization. A Laboratory Manual. USA: Academic
                                                                        Press. A Division of Harcourt    Brace and Company,
REFERENCES                                                              California, 1998.

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