ВЛИЯНИЕ ЭЛЕКТРОМАГНИТНОЙ ОБРАБОТКИ НАПОЛНИТЕЛЯ НА ЭМИССИЮ ФОРМАЛЬДЕГИДА ИЗ КЛЕЕВОЙ КОМПОЗИЦИИ

INFLUENCE OF ELECTROMAGNETIC TREATMENT OF FILLER ON FORMALDEHYDE EMISSIONS FROM ADHESIVE COMPOSITION

доктор технических наук, профессор кафедры химии Бельчинская Л.И.1 аспирант кафедры химии Анисимов М.В.1 доктор химических наук, академик Седлячек Я.2 кандидат технических наук,

заместитель директора ОАО «Графское» Степанов А.В.3 1 - ФГБОУ ВПО «Воронежская государственная лесотехническая академия»

  • 2 - Технический университет Зволена (Словакия)
  • 3 - ОАО «Графское»

Belchinskaya L.I., Anisimov M.V., Sedliacik J., Stepanov A.V.

  • 1 - FSBEIHPO "Voronezh State Academy of Forestry"
  • 2 - Technical University in Zvolen (Slovakia)
  • 3 - JSC "Grafskoye"

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DOI: 10 Л2737/3024

Abstract. The effect of prior activation of natural zeolite filler (clinoptilolite) for adhesive compositions in the microwave electromagnetic field (EMF microwave) and a weak pulsed field (IMP) on the him adsorption-desorption properties was determined. The differences in the mechanisms of EMF exposure and weak microwave UTI on adsorption capacity of clinoptilolite was detected. Decrease of level of free formaldehyde emission of the cured adhesive composition is 23 %.

Keywords: clinoptilolit, adsorption, desorption, adhesive composition, electromagnetic activation.

The most widely using in the production of modern MDF wood-based materials received urea resins (UFR). In Europe, the proportion of UFR is 83% from the total binder of using adhesives, in Russia, this figure corresponds to 85%. Widespread this adhesives is received due to their technological, operational and economic properties. However, a significant disadvantage of these adhesives is their toxicity, which is determined by the content of free formaldehyde, which emissions leads to contamination of the premises. Proved ecotoxicity formaldehyde at the cellular level, it is a potent mutagen which severely affects the specific stage of cell cycles, it induces the emergence and growth of cancerous tumors, accumulates in the bone marrow. Adverse effect of formaldehyde on the central nervous system was defined.

In connection with this reduction of emission of free formaldehyde is important for modern manufacturing of glued materials. In papers [1,2] for the manufacture of environmentally friendly plywood attempts to use heat treatment of clinoptilolite, which was applied to the adhesive composition as a sorbent filler. Application of thermal activation significantly increases the adsorption properties of of clinoptilolite, however, this type of treatment characterized processing time, resulting sintering and partial destruction of the structure of the mineral. Besides heat treatment requires the introduction of clinoptilolite in the adhesive composition immediately after activation, which is not possible due to the high temperature of the mineral, which method does not comply with use of a binder in the production. Solving of this problem is achieved by storage of the activated mineral without air until it reaches room temperature, that raises a number of technological and economic costs. Using in this paper activation methods are more economical by reducing the activation time (up to 120 fold) compared with heat treatment.

A series of works by activating the surface of the sorbent under natural electromagnetic field (EMF) and weak microwave IMP held. Optimal treatment regimens previously defined in [3]: for EMF microwave power microwave field - 800 W, the processing time - 4 min. For the treatment IMP - 0.5 min., Magnetic induction 71 mT.

The most commonly used fillers in the timber industry are kaolin and wood flour. Wood flour is used in the form of finely chopped, of dried wood with a fibrous structure, traditionally obtained from conifers. Introduction of the wood meal in the adhesive composition increases the water resistance of the bond, but the effect is short-lived [4].

Kaolin is a clay mineral.lt has a tough skeletonized structure.lt is traditionally used as a glue filler based on URF in the prosess of making plywood. The moisture content of the mineral is about 3%, porosity -13%, surface area ranges from 8 to 70 м2/г [5]. In accordance with the received data [6] adsorption capacity of kaolin by formaldehyde is low (2 мг/г), that does not allow its use as a sorbent of formaldehyde, which is improve performance adhesives and finished plywood that does not allow its use as a sorbent of formaldehyde, which is improve performance adhesives and finished plywood. Heat treatment or reagent activation mineral can improve its adsorption capacity for a number of toxic substances [5], however, this effect was not observed in respect of sorption formaldehyde. Therefore, kaolin is traditionally used only as a filler adhesive compositions.

In this paper, partially replaced the kaolin and wood flour clinopti- lolite.

Clinoptilolite is a natural nanoporous mineral with wireframe structure, having active centers of different nature: unshielded (or partially shielded) cations, complexes from multiply charged cations and hydroxyl groups, Bronsted and Lewis acid sites, bridging oxygen atoms, defects of crystal's structure [7]. Size and location of channels for sorption processes is crucial. Besides the channels structure of zeolite contain voids, which together with the channels forming polyhedral, which have the size of the free volumes of 0.6-1.1 nm. In clinoptilolite structure there are four types of channels of elliptical cross. Dimensions of decimal channels are 0,705 x 0,425 nm, and eight— 0,46 x 0,395 nm. Dimensions of decimal channels are 0,705 x 0,425 nm, and eight— 0,46 x 0,395 nm. Matrix of clinoptilolite has wireframe open structure, exchange's ion is located in the open cavities and channels [8]. Natural clinoptilolite has a low adsorption capacity (6 mg/g), in this connection there are different ways to activate it: heat treatment, modification by reagent (acid or alkaline). However, these methods of activation is difficult due to several of technological features of making adhesives. As mentioned above, the introduction of the adhesive composition immediately after thermal activation of clinoptilolite leads to premature curing of the binder. A similar effect was observed upon addition of the mineral kislotnoaktivirovanno- go. Alkaline activation requires changes in adhesive formulations as increasing the amount of hardener, which is economically costly.

As sorbent-filler adhesive composition used is a natural mineral clinoptilolite (K95) Slovak origin, the content of the clinoptilolite, and 95% 5% hydromica particle size of 20 microns.

Russian resin KF-and low-toxic N66F Slovak KRONORES CB1100 resin used for the manufacture of plywood. Hardener of the adhesive composition used ammonium chloride, used in industry for hot curing process. The formulations used and the ratio of adhesive fillers 1 and 2 are shown in Table 1.

Table 1 - Formulations of used adhesive

№ Sample

Glue (pbw)

Hardener

(pbw)

Filler 1 (pbw)

Filler 2 (pbw)

Sample 1

KRONORES CB 1100(100)

Ammonium chloride (0,8)

Wood flour (10)

-

Sample 2

KRONORES CB 1100(100)

Ammonium chloride (0,8)

Wood flour (7,8)

Unactivated clinoptilolite (2,2)

Sample 3

KRONORES CB 1100(100)

Ammonium chloride (0,8)

Wood flour (7,8)

Clinoptilolite, activated in the microwave (2,2)

Sample 4

KRONORES CB 1100(100)

Ammonium chloride (0,8)

Wood flour (7,8)

Clinoptilolite, activated in IMP (2,2)

Sample 5

Resin KF-N66F (100)

Ammonium chloride (0,6)

Kaolin

(10)

-

Sample 6

Resin KF-N66F (100)

Ammonium chloride (0,6)

Kaolin

(7,8)

Unactivated clinoptilolite (2,2)

Sample 7

Resin KF-N66F (100)

Ammonium chloride (0,6)

Kaolin

(7,8)

Clinoptilolite, activated in the microwave (2,2)

Sample 8

Resin KF-N66F (100)

Ammonium chloride (0,6)

Kaolin

(7,8)

Clinoptilolite, activated in IMP (2,2)

Emission of free formaldehyde from the cured adhesive composition was determined by photocolorimetry acetylacetone [9].

During operation it was found lowering of free formaldehyde emission from the cured adhesive compositions, when introduced into it clinoptilolite activated at low EMF and microwave IMP data presented in Table 2.

Table 2 - Emission of formaldehyde from the cured adhesive composition.

№ Sample

Valid values for the emission from the adhesive composition

l

2

3

4

5

6

7

8

Emission of formaldehyde from the cured adhesive composition, C, mg/m3

0,124

0,082

0,080

0,070

0,074

0,128

0,126

0,104

0,115

t), %

5

34

  • 2
  • 35
  • 15
  • 44
  • 10
  • 40

5

2

  • 23
  • 23
  • 11
  • 8

* Note - The numbering of samples taken from Table 1; r) - the degree of reduction in formaldehyde emissions in comparison a) with industrially manufactured samples (numerator), b) valid values emission from adhesive composition (denominator).

Activation of clinoptilolite in EMF microwave is more efficient than IMP. The greatest impact on the reduction of emissions of formaldehyde has activation in EMF microwave compared with IMP. The initial concentration of formaldehyde in the resin reflected on degree of reduction in the level of free formaldehyde emission and largely affects the processing in IMP. Formaldehyde emissions from the adhesive composition corresponds to the content of monomeric formaldehyde in UFR: the amount of free formaldehyde in KRONORESS resin is 0,1%, in resin KF-N66F - 0,14%. Activation in IMP provides reductions of free formaldehyde emissions on 11% for domestic glue and on 10% for Slovak resin. Processing in EMF microwave field reduces formaldehyde emissions by 23 and 15% respectively.

The mechanism of influence of EM fields on the complex structure of clinoptilolite is different. At influence of weak IMP, according Buchachenko, Binge approaches, etc. [10-14], activation occurs at the level of the spin subsystem. Clinoptilolite structure is a complex system, where probably is a polarization of acidic and basic groups of SiOH, A10H, FeOH, MgOH, hydroxylated cations and other [15], and, as a consequence, the formation of radical pairs, which are active adsorption centers. Thus, weak IMP stimulates nonequilibrium state with the excitation of additional active centers, which have a high adsorption activity.

When exposed to microwave electromagnetic field is an intensive absorption of electromagnetic wave energy, to a greater extent by dipoles of water, as a result they begin to rotate continuously perpendicular to the direction of motion of the electromagnetic wave, and ions in the mineral structure acquire often alternating directional position toward action lines of force. All these processes lead to rapid heating of the sample (fractions of seconds) [16], with rupture of intermolecular bonds between water molecules and structural matrix clinoptilolite, leading to the evaporation of adsorbed water and the appearance of additional active sites.

Findings

  • 1) Determine the reduction of emissions of free formaldehyde from cured adhesive composition based on Slovak resin KRONORES CB 1100 (KR) and russian resin KF-N66F (KF).
  • 2) When using clinoptilolite activated in microwave EMF selection of free formaldehyde from adhesive composition is reduced by 15% for Slovak resin, by 23% for russian resin. Activation IMP reduces emissions of free formaldehyde by 10% and 11% respectively, for the studied resins.
  • 3) Effect of activation mechanisms due to the difference of EMF micro- wave exposure and weak IMP on the adsorption capacity of clinoptilolite. Activation in microwave EMF is more conducive to dehydration clinoptilolite, which increases the number of active center of the mineral. Processing contributes to the structuring of IMP clinoptilolite and the formation of new active centers.

Acknowledgments

The researches were carried out within the ECONANOSORB Europeanproject under the frames of Marie Curie Actions FP7-PEOPLE-IRSES-295260.

References

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УДК 630*377

 
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