Production Of Epoxy Resins Research Articles

Coexposure to epichlorohydrin on the elimination of urinary metabolites of dimethylformamide.

N,N-Dimethylformamide (DMF) is an important industrial organic solvent. It is a well-known hepatotoxicant (Lundberg et al. 1981, Wang et al. 1991). Its reproductive effect is also documented in literature (Ducatman et al. 1986, Levin et al. 1987). Due to its low vapor pressure and high lipid solubility, the major occupational exposure route is through skin and mucous membrane (Lauwerys et al. 1980). In the past, the major occupational exposure to DMF in Taiwan occurred in the synthetic leather industry (Wang et al. 1991). Recently, however, results of occupational environmental monitoring have revealed that the newly evolved multi-billion-dollar electronics industry also uses large volume of DMF. A direct-acting mutagen, epichlorohydrin (ECH, 1,2-epoxy-3-chloropropane), is also heavily used in the electronics industry. It is used in the production of epoxyresins and printed circuit board. In manufacturing of the latter, DMF is also used.

Review of trimellitic anhydride (TMA) induced respiratory response.

Acid anhydrides such as trimellitic anhydride (TMA) are of interest due to their important industrial uses and to their adverse health effects in exposed populations. Important industrial uses of TMA include the production of epoxy and alkyd resins used to manufacture a variety of coating materials. The adverse health effects are a result of its direct irritant effects on mucosal surfaces in all exposed humans as well as its ability to cause immunologic sensitization in a small proportion of humans. In those individuals who are immunologically sensitized, reexposure to TMA can result in well described immunologic syndromes: asthma-rhinitis, late respiratory systemic syndrome (LRSS), and very rarely pulmonary disease anemia syndrome (PDA). In summary, adverse health effects of TMA are due to its effects as an irritant, an immunologic sensitizer, or a combination of both.

Role of changes in renal hemodynamics and P-450 metabolites of arachidonic acid in the reversal of one-kidney, one clip hypertension.

To examine the role of changes in renal hemodynamics and P-450 metabolites of arachidonic acid in the reversal of one-kidney, one clip (1-K,1C) hypertension in rats. The stimulus for the release of an antihypertensive lipid from the kidney is not known. This study examined whether cortical or papillary blood flow is altered after removal of the clip from the renal artery of 1-K,1C hypertensive rats, and the effects of blockade of the renal metabolism of arachidonic acid by P-450 with 17-octadecynoic acid (17-ODYA) on the fall in blood pressure. Cortical and medullary blood flows were measured using laser-Doppler flowmetry. 17-ODYA (33 nmol/min) was infused directly into the renal artery to examine the effect of inhibition of renal P-450 activity on reversal of 1-K,1C hypertension. The renal metabolism of arachidonic acid in control and in 1-K,1C hypertensive rats was assessed by incubating microsomes with [14C]-arachidonic acid, the metabolites formed being measured using reverse-phase high-performance liquid chromatography. The antihypertensive effects of these P-450 metabolites of arachidonic acid were compared with those of medullipin I after intravenous administration in conscious spontaneously hypertensive rats (SHR). Cortical and papillary blood flow increased significantly and arterial pressure fell after unclipping the renal artery in the 1-K,1C hypertensive rats. 17-ODYA prevented the fall in blood pressure after unclipping. The production of epoxy- and dihydroxy-eicosatrienoic acids was elevated in microsomes prepared from the renal cortex of the 1-K,1C hypertensive rats. However, intravenous administration of these metabolites did not mimic the effect of medullipin I to lower arterial pressure in SHR. Elevations in renal cortical or papillary blood flow, or both, may stimulate the release of a P-450-derived antihypertensive lipid from the kidney after unclipping of the renal artery in 1-K,1C hypertensive rats. However, it is unlikely that this substance is a P-450 metabolite of arachidonic acid.

Fire performance studies on glass‐reinforced plastic laminates

AbstractPolyester, epoxy and phenolic glass‐reinforced laminates were compared in terms of their fire properties in the cone calorimeter. The presence of a gel coat on the polyester and epoxy products had some effect, mainly in the FR grades. The FR polyester with a brominated flame retardant showed a marked decrease in rate of heat release and in rate of smoke production. Aluminium hydroxide (commonly called alumina trihydrate of ATH) caused a significant delay in ignition time for the epoxy product and some reduction in rate of heat release but rate of smoke release was still relatively high. Phenolic laminates showed a long ignition time and relatively low rate of heat release (RHR). The peak RHR was further reduced by the presence of aluminium hydroxide and by changing the type of glass reinforcement. The influence of thickness was explored for a series of phenolic laminates in both cone calorimeter and the International Maritime Organization (IMO) surface flammability test. Ignition delay time was significantly affected and the cone calorimeter results showed that the shape of the RHR curve was also changed as the thickness increased. However, the heat release measurements in the IMO test were not sensitive enough to pick up the differences in this property. The type of substrate under the laminate significantly altered the burning rate but this may have been because they were not glued or mechanically fixed.

Production of unsaturated carbonyl compounds during metabolism of hydroperoxy fatty acids by colonic homogenates

Recent evidence has suggested that unsaturated carbonyl compounds may be the ultimate mitogens produced from the primary auto-oxidation products of unsaturated fatty acids. The present study has investigated the metabolism of 13-hydroperoxyoctadecandienoic acid (13-ROOH) by rat colon homogenates. This hydroperoxide is one of the primary products formed from the oxygenation of linoleic acid, the most abundant dietary polyunsaturated fatty acid. Incubation mixtures contained [1-14C]13-ROOH and colonic homogenates prepared from male Sprague-Dawley rats. After 30 min of incubation the reaction was quenched and the products extracted for analysis by HPLC. The identity of the eluted products were verified by UV, MS and NMR spectroscopy. The major products include a mixture of isomers of 2,4-dienone C18 fatty acids and 13-hydroxyoctadecadienoic acid. Direct comparison of homogenate metabolism to the hematin-catalyzed, alkoxyl radical-mediated decomposition of 13-ROOH shows some significant differences. In particular, no epoxy products are detected in the presence of tissue homogenates whereas these are the major products observed during the decomposition of 13-ROOH by hematin and a number of other agents. These experiments demonstrate the production of relatively large amounts of unsaturated carbonyl-containing fatty acids during the metabolism of hydroperoxy fatty acids by colonic tissue. The major product, 13-oxo-9Z,11E-octadecadienoic acid, when instilled intrarectally stimulates the incorporation of [3H]deoxythymidine into colonic mucosal DNA, and induces colonic mucosal ornithine decarboxylase activity in vivo. These findings have important implications for the mechanism by which dietary fat promotes colon tumorigenesis as the formation of relatively reactive 2,4-dienones may be a key to the in vivo mitogenic activity of oxidized fatty acids.

Determination of oligomer 340 and polyamines in cured epoxy resins by extraction and high-performance liquid chromatography

The efficiency of acetone in extracting unreacted oligomer 340 and aliphatic polyamine hardeners (diethylenetriamine and triethylenetetramine) from cold-cured epoxy resins was studied. Finely scratched slices of cured resin were extracted ultrasonically with acetone. The extracted oligomer 340 and polyamines were determined by high-performance liquid chromatography. The extraction efficiency of acetone for unreacted oligomer 340 was over 90% and that for the polyamines varied from 76 to 97%. The procedure was applied to study the curing rate of five commercial epoxy resins. The unreacted amounts of both oligomer 340 and polyamine decreased rapidly within 1–2 d in all the products studied. After curing for 2–3 d the unreacted amounts decreased only slowly. The proposed method can be used to evaluate health risks of cured epoxy products and to obtain information about curing kinetics.

Contact allergy to an epoxy reactive diluent: 1,4-butanediol diglycidyl ether.

3 female workers in a brush factory developed contact allergy from a 2-component epoxy glue containing epoxy resin (37% w/w), reactive diluents: i.e., 1,4-butanediol diglycidyl ether (BDDGE) 3%, glycidyl ethers of aliphatic alcohols (Epoxide 8) 0.03% and phenyl glycidyl ether (PGE) 0.01%; and inert fillers. All 3 patients were positive to the resin component of the glue and to BDDGE, indicating that BDDGE was the main allergen. 2 of the patients reacted to PGE, but none to the 3rd reactive diluent (Epoxide 8) in the glue. 2 of the patients did not react to epoxy resin, indicating that BDDGE may be an even stronger sensitizer in humans than epoxy resin, and that it does not cross-react with epoxy resins. Permeation studies revealed that BDDGE penetrates disposable PVC and rubber gloves in less than 30 min; thus, contaminated gloves should be replaced immediately. Reactive diluents should be included in patch test series if contact allergy to epoxy products is suspected.

Cocarcinogenicity of phenols from Estonian shale tars (oils).

Many phenols have carcinogenic activity. The Estonian shale oils contain up to 40 vol % phenols. The promoting activity after initiation of phenols of Estonian shale oils was tested in mice with a single subthreshold dose (0.36 mg) of benzo(a)pyrene. C57Bl and CC57Br mice were used in skin painting experiments. Weak carcinogenic activity was found in the total crude water-soluble phenols recovered from the wastewater of a shale processing plant. In two-stage experiments a clear promoting action of the total crude phenols was established, whereas the fractions A and B (training reagents), obtained by selective crystallization of the total phenols exerted a considerably weaker promoting action. Epo-glue, a commercial epoxy product produced from unfractionated crude phenols, had no promoting activity, which may be due to the processing of the phenols involving polymerization. The mechanism of action of phenols is not clear. According to some data from the literature, phenol and 5-methylresorcinol reduce the resorption speed of BP in mouse skin, causing prolongation of the action fo the carcinogen.

Cocarcinogenicity of Phenols from Estonian Shale Tars (Oils)

Many phenols have carcinogenic activity. The Estonian shale oils contain up to 40 vol % phenols. The promoting activity after initiation of phenols of Estonian shale oils was tested in mice with a single subthreshold dose (0.36 mg) of benzo(a)pyrene. C57Bl and CC57Br mice were used in skin painting experiments. Weak carcinogenic activity was found in the total crude water-soluble phenols recovered from the wastewater of a shale processing plant. In two-stage experiments a clear promoting action of the total crude phenols was established, whereas the fractions A and B (training reagents), obtained by selective crystallization of the total phenols exerted a considerably weaker promoting action. Epo-glue, a commercial epoxy product produced from unfractionated crude phenols, had no promoting activity, which may be due to the processing of the phenols involving polymerization. The mechanism of action of phenols is not clear. According to some data from the literature, phenol and 5-methylresorcinol reduce the resorption speed of BP in mouse skin, causing prolongation of the action fo the carcinogen.

Synthesis of novel alkyl‐aryl polyamide

AbstractA laboratory procedure for synthesizing an alkylaryl polyamide curing agent for liquid epoxy resins from commercially available, low cost materials is given. The various chemical reactions required to obtain the desired end‐product are described, and several properties of the novel polyamide are listed. This agent was found suitable for producing foamed or frothed epoxy products.

Materials for diphenylolpropane production equipment

Diphenylolpropane is one of the main s t a r t i n g components in the product ion of epoxy r e s i n s . At the F r e e Labor p a i n t a n d v a r n i s h coat ings plant , d iphenylolpropane is obtained by condensat ion of phenol with acetone in a su l fu r ic ac id medium with a s t a r t i n g su l fu r i c acid concentra t ion of 73-74~c and a f inal one of 65% in the p r e s e n c e of 0.1-0.2% th iog lyco l ic acid at 40~