The 5th ISFR (October 11-14, 2009, Chengdu, China)

TREATMENT OF PHENOL RESIN FOAM POWDER AND
PREPOLYMER IN HIGH-TEMPERATURE WATER
Yukihiro Sugiyama,1 Akiko Miura,1 Takahiro Konishi,2 Hideyuki Tagaya*1
1Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan,Yonezawa, Yamagata 992-8510, Japan.
E-mail: tagaya@yz.yamagata-u.ac.jp
2Sekisui Chemical Co. Ltd. 3-17, Toranomon, Minato-ku,
Tokyo 105-8450, Japan.

Abstract: In this study waste plastics such as phenol resin foam powder were decomposed
into their monomer compounds in sub- and supercritical water. Water plays important roles asstable physical medium at high temperature and reactive chemical reagents to accelerate
decomposition reaction of the thermosetting resin. In the decomposition reaction, methylene
bonds were cleaved easily via the ionic reaction by water. The water participating mechanism
was confirmed to make clear the decomposition products of phenol resin foam.
1. Introduction
It is well known that water under sub- and supercritical conditions is much less polar andcan homogenize substantial amounts of non-polar organic compounds. Also the hightemperature water including supercritical water is emerging as a medium which could provide
the optimum conditions for a variety of chemical reactions, among them the decomposition ofpolymeric compounds [1]. We have already confirmed that waste plastics such as phenol resin
decomposed into their monomeric compounds in sub and supercritical water [2 ~ 7]. In thisstudy waste plastics such as phenol resin foam powder were decomposed into their monomer
compounds in sub- and supercritical water. Water plays important roles as stable physicalmedium at high temperature and reactive chemical reagents to accelerate decomposition
reaction of the thermosetting resin. In the decomposition reaction, methylene bonds werecleaved easily via the ionic reaction by water. The water participating mechanism wasconfirmed to make clear the decomposition products of phenol resin foam and modelcompounds including prepolymer.
2. Experimental
Waste organic compounds were reacted after pulverizing. A 10ml tubular bomb reactor
was used as the reactor in which the reaction temperature was attained within 2 min [8]. The
typical reaction was carried out for 0.1g of waste organic compounds in 1~ 5ml of water with- 250 -PARTⅤ SOLVOLYSIS
or without additives. Prepolymer and 4,4’-methylenediphenol was used as model compoundof phenol resin foam. NaCl, KCl, CsCl, KI, CaCl2, NH4OH, and Na2CO3 were used as theadditive.
After the reaction, products were extracted by ether and measured by GC/MS and GC.
The yield of products was defined by product(g)/reactant(g). Main products were phenol andalkylphenols. In the thermal analysis of organic resources, the temperature increasing rate was10oC / min.
Prepolymer of phenol resin was prepared by the polymerization reaction of pure phenol
and recovered mixtures of phenol, cresols and alkyl phenols in acidic conditions. Molecularweight distributions of prepared prepolymer were measured by GPC.
3. Results and Discussion
3.1 Decomposition reaction of phenol resin foam
Phenol resin foam was pulverized and reacted at 430oC. More than 50% of the foam wasconverted to monomeric compounds. To obtain information on the reactions at mildconditions, the resin was reacted at 300 to 380oC as shown in Fig.1. Conversion increased
with an increase in the reaction temperature and total yields of identified monomer
compounds increased with temperature.
Na2CO3 was more effective additive than NH4OH on the decomposition reaction.
However, high yield of oligomer was expected in the reaction adding NH4OH.
3.2 The effects of the time on the decomposition reaction of phenol resin foam
In the reaction at 320oC, conversion gradually increased as shown in Fig. 2. It suggested
the possibility to obtain high yields of the decomposition also at mild reaction conditions.
9090(a)(b)

70

water-soluble
Residue(%)

8060

residue

Yield

8050Yield(%)

7060
5040403030202010100300

320 340
360
Temperature (oC)380

2,6dimethyl
phenol02,5-dimethyl
phenolp-cresolo-cresol
phenol300

320340360
Temperature (oC)380

Fig. 1. The effect of temperature and additive on the decomposition reaction of phenol
resin foam (a) Na2CO3, (b) NH4OH- 251 -The 5th ISFR (October 11-14, 2009, Chengdu, China)
water-soluble
Residue

90

Yield

(%)

80
70

residue

60

2,6dimethyl
phenol50

2,5-dimethyl
phenol4030

p-cresol

20o-cresol

10phenol

012345Time(h) reaction of phenol resin foam at 320 oC
Fig. 2 Decomposition

3.3 Decomposition reaction of 4,4’-methylenediphenol
To attain information on the decomposition reaction mechanism of phenol resin, modelcompound of resin, 4,4’-methylenediphenol was reacted. Conversion and yield of monomericcompounds increased when temperature increased as shown in Fig.3. Phenol yield was fairly
small in the reaction at below 250 ºC. Products were obtained in the row of phenol, p-cresol,and o-cresol. However, the total product yields are too small to explain the conversion.
Therefore, 4,4’-methylenediphenol was converted to unidentified products which can not beobserved in GC and GC-MS spectra. It was considered the presence of dehydrogenation
condensation reaction. We already found the production of trimer of phenol [9].
3.4 Effects of inorganic additives on the decomposition reaction
Effects of inorganic additives on the decomposition reaction of 4,4’-methylenediphenol
were studied. We have already confirmed that the addition of neutral salts such as NaCl waseffective for the decomposition reaction. To obtain information on the positive effect ofneutral salts, decomposition reactions by adding various alkali halides were carried out.
Addition of alkali halide increased conversion of 4,4’-methylenediphenol and yields of phenoland p-cresol. NaCl was the best additive among them.

Fig. 3 Decomposition reaction of 4,4’-methylenediphenol- 252 -

PARTⅤ SOLVOLYSIS
3.5 Dehydrogenation reaction in supercritical water
To obtain information on the decomposition reaction mechanism, dehydrogenation
reaction in supercritical water was studied. 1-naphthol and methanol were reacted insupercritical water as shown in Fig.4. Naphthalene, 1-methylnaphthalene, 2-methylnaphtalene,methylnaphthol, and dimethylnaphthol were produced. Naphthalene, 1-methylnaphthalene,and 2-methylnaphtalene were produced through decomposition reactions by water.
Methylnaphthol and dimethylnaphthol were produced through dehydrogenation reaction bymethanol. These kind of dehydrogenation reaction might occur in the decomposition reactionof 4,4’-methylenediphenol.

OHCH3CH3OH

CH3(CH3)205

1015

20

25

30

Retention time (min)Fig. 4 GC-MS analysis of dehydrogenation reaction of 1-naphthol in supercritical water3.6 Synthesis of Phenol Resin by Using Decomposition Products of Waste Polymers
The prepolymer of phenol resin was prepared by the conventional preparation methodfrom the decomposition products. Two kinds of the prepolymer of phenol resin were preparedby using the pure phenol and decomposition products of polycarbonate. Formaldehyde andthe hydrochloric acid are added to the phenol or decomposition products, and then wereheated at 85°C with stirring for 2h. The obtained products were cooled, and were heated at175°C to remove un-reactive materials. Thus, the molecular weights of solid products weredetermined by GPC analysis.
The prepolymer yield prepared by using pure phenol was 71.0% while the yield using
decomposition products was 51.2%. The molecular weight of products prepared by using
decomposition products was almost equal to the molecular weight of the prepolymer
synthesized from the pure phenol, suggesting that the prepolymer of phenol resin can besynthesized by using decomposition products.

4. Conclusions
We have studied decomposition reaction of phenol resin foam and
4,4-methylenediphenol to make clear the decomposition reaction mechanism of phenol resin- 253 -The 5th ISFR (October 11-14, 2009, Chengdu, China)
in high temperature water. From the effect of reaction temperature, we have concluded thatthe reaction which produces phenol and the reaction which produces p-cresol and o-cresol do
not occur at the same time. This suggestion is supported by the effect of reaction time. From
the tendency of efficiency of salts as catalyst, water molecule attacks to methylene bond of
4,4’-metylenediphenol was suggested. This suggestion is supported by the effect ofconcentration of water which is used for this reaction. Under these conditions, not only
decomposition reactions, but also condensation reactions occur. This fact was supported by
the fact in the reaction of methanol and aromatic compounds.
References[1] T. Sako (Ed.), Chorinkai Ryutai, Agne shofusha, Japan, 2001.
[2] Y. Suzuki, H. Tagaya, T. Asou, J. Kadokawa, K. Chiba, Ind. Eng. Chem.Research, 1999,
38,1391.
[3] H. Tagaya, K. Kato, J. Kadokawa, K. Chiba, Polymer Degradation and Stability, 1999, 64,289.
[4] Z. Dai, B. Hatano, J. Kadokawa, H. Tagaya, Polymer Degradation and Stability, 2002, 76,
179.
[5] Y. Shibasaki, T. Kamimori, H. Tagaya, Polymer Degradation and Stability, 2004, 83, 481.
[6] H. Tagaya, Y. Shibasaki, C. Kato, J. Kadokawa, B. Hatano, J. Mater Cycles Waste
Manag.,
2004, 6, 1.
[7] A. Ikeda, K. Katoh, H. Tagaya J. Mater. Sci., 2008, 43, 2437.
[8] S. Townsend, M. Abraham, G. Huppert, M. Klein, S. Paspek, I&EC Research, 1988, 27,
143.
[9] H. Tagaya, Y. Suzuki, N. Komuro, J. Kadokawa, J Mater Cycles Waste Manag.,2001,3,32-37.

- 254 -