Splicing Veneer Formaldehyde Emission Comparison

Splicing Veneer Formaldehyde Emission Comparison

In 2006, Tembec (now LRGB Chemicals) conducted a test to determine the formaldehyde emission levels of its S-315 veneer splicing glue and to compare the glue with PVA veneer glue. The results were positive: veneer with S-315 veneer splicing glue emitted only 0.01 mg/L more than veneer with PVA glue—within the experiment’s margin of error. The experiment showed that veneer manufacturers need not opt for PVA over Tembec’s splicing glue because of Tembec’s use of formaldehyde. The environmental impact of both glues in terms of formaldehyde emissions is essentially the same.

For your benefit, we’ve posted the technical report below.

Introduction

Nowadays, with the attention given to some environmentalists, the concern with the formaldehyde emissions is constantly growing. For the splicing industry, it is to a point that manufacturers are asked to use glues that do not contain any formaldehyde. As of now, the only type of product complying with that condition was PVA resins.

Although they apparently do not contain formaldehyde, the use of PVA resins reportedly creates handling and manufacturing problems. There is on the market different performant products that could be used to alleviate these production hurdles if the formaldehyde issue could be settled. It was believed by the R&D team at Tembec [now LRGB Chemicals] that even if the resin itself contains some formaldehyde, the glue line once properly cured should not emit more formaldehyde than the wood itself. Therefore, this report describes the results of the veneer dessicator test done at Forintek for Placages Nicolet-Sud to compare the formaldehyde emissions of PVA and S-315 to wood alone.

Testing

The samples were collected at Nicolet and brought to Forintek for testing following a suggested protocol within the same day. To insure a valid comparison, the amount of variables having an impact on results was reduced to the minimum possible. Therefore, samples were taken from the same flitch of mahogany wood, the press platen was scraped before use to prevent contamination and all veneers were pressed in the same press under the same conditions.

The pressing sequence was: veneers alone, veneers with PVA and veneers with S-315. Also, samples were randomly taken from each veneer sheet after pressing making sure the glue line was in the middle of the sample if there was any. Note that testing has been conducted in accordance with the American Society for Testing and Materials Standard designed as ASTM D 5582-00. See figure 1 below for more details on test conditions.

Test conditions

All samples were conditioned for 7 days at 240C ± 20 C and 50%RH ± 5%RH before testing. The correlation curve used to convert mg/L into ppm was built from particleboard and MDF desiccator and large chamber emission results, which means that the correlation results should be taken with caution. ANSI A208.I and ANSI A208.2 standard value of 0.30 parts per million (ppm) is set for particleboard and NfDF products.

Results

Complete data can be found under table 1. The main objective of this test was to evaluate how the emissions of veneers glued with S315 would compare with wood alone emissions. A PVA resin was included in this experiment to compare the level of UF resin emission to the recommended resin. Samples were strictly evaluated for formaldehyde emissions. Overall the results were positive. It was found that the wood type tested contained naturally 0.02 ppm of formaldehyde. Although S-315 showed a slightly higher formaldehyde concentration on a small scale, it is comparable to PVA once correlated to the large chamber concentration at 0.03 ppm.

It is important to mention here that such a difference in concentration is within experimental uncertainty. Since PVA was believed to be formaldehyde free, it was expected that it would have the same emission level as the wood alone. Even though 0.01 ppm is a very small amount of formaldehyde, surprisingly, both resins showed slightly higher emissions. That being said, results obtained during this test are all very far from the current formaldehyde norm of 0.3 ppm.

Table I: Dessicator test results

Samples Id Date of Test Concentration in (mg/L)

Desiccator method

Correlated to the “Large Chamber”

ASTM E 1333-02

Concentration m

Veneer Tembec:

Pascale Martel; 15

09-06

September 25, 2006 0.042 0.02
Veneer with glue; Tembec:

Pascale Martel; 15-09-06

September 25,2006 0.076 0.03
Veneer with

PVA; Tembec:

Pascale Martel, 15-09-06

September 25,2006 0.064 0.03

Recommended Next Step

Since formaldehyde emissions with this product are comparable to PVA, the R&D Resin Division team [at LRGB Chemicals] recommends pursuing the use of S-315 given the good results obtained and the production advantages it provides.

Report prepared by Pascale Martel, Technical Coordinator, Resin Division
Nov. 23, 2006

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