SE545882C2 - An adhesive composition for wood panel composites - Google Patents
An adhesive composition for wood panel compositesInfo
- Publication number
- SE545882C2 SE545882C2 SE2151634A SE2151634A SE545882C2 SE 545882 C2 SE545882 C2 SE 545882C2 SE 2151634 A SE2151634 A SE 2151634A SE 2151634 A SE2151634 A SE 2151634A SE 545882 C2 SE545882 C2 SE 545882C2
- Authority
- SE
- Sweden
- Prior art keywords
- adhesive composition
- range
- isocyanate
- das
- composition according
- Prior art date
Links
- 239000000853 adhesive Substances 0.000 title claims abstract description 40
- 230000001070 adhesive effect Effects 0.000 title claims abstract description 40
- 239000000203 mixture Substances 0.000 title claims abstract description 40
- 239000002023 wood Substances 0.000 title claims abstract description 16
- 239000002131 composite material Substances 0.000 title claims abstract description 14
- 229920002678 cellulose Polymers 0.000 claims abstract description 24
- 239000001913 cellulose Substances 0.000 claims abstract description 24
- 239000001254 oxidized starch Substances 0.000 claims abstract description 21
- 235000013808 oxidized starch Nutrition 0.000 claims abstract description 21
- 239000012948 isocyanate Substances 0.000 claims abstract description 18
- 150000002513 isocyanates Chemical class 0.000 claims abstract description 18
- 229920001046 Nanocellulose Polymers 0.000 claims abstract description 9
- 239000002159 nanocrystal Substances 0.000 claims abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 33
- 229920002472 Starch Polymers 0.000 claims description 20
- 235000019698 starch Nutrition 0.000 claims description 18
- 239000008107 starch Substances 0.000 claims description 17
- UPMLOUAZCHDJJD-UHFFFAOYSA-N 4,4'-Diphenylmethane Diisocyanate Chemical compound C1=CC(N=C=O)=CC=C1CC1=CC=C(N=C=O)C=C1 UPMLOUAZCHDJJD-UHFFFAOYSA-N 0.000 claims description 16
- 125000002485 formyl group Chemical class [H]C(*)=O 0.000 claims description 15
- 230000003647 oxidation Effects 0.000 claims description 15
- 238000007254 oxidation reaction Methods 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 12
- 239000011094 fiberboard Substances 0.000 claims description 9
- DVKJHBMWWAPEIU-UHFFFAOYSA-N toluene 2,4-diisocyanate Chemical compound CC1=CC=C(N=C=O)C=C1N=C=O DVKJHBMWWAPEIU-UHFFFAOYSA-N 0.000 claims description 6
- 125000005442 diisocyanate group Chemical group 0.000 claims description 4
- LCPNYLRZLNERIG-ZETCQYMHSA-N (2S)-6-amino-2-[2-(oxomethylidene)hydrazinyl]hexanoyl isocyanate Chemical compound NCCCC[C@H](NN=C=O)C(=O)N=C=O LCPNYLRZLNERIG-ZETCQYMHSA-N 0.000 claims description 3
- 239000011120 plywood Substances 0.000 claims description 3
- ZVEMLYIXBCTVOF-UHFFFAOYSA-N 1-(2-isocyanatopropan-2-yl)-3-prop-1-en-2-ylbenzene Chemical compound CC(=C)C1=CC=CC(C(C)(C)N=C=O)=C1 ZVEMLYIXBCTVOF-UHFFFAOYSA-N 0.000 claims description 2
- 235000013339 cereals Nutrition 0.000 claims description 2
- KORSJDCBLAPZEQ-UHFFFAOYSA-N dicyclohexylmethane-4,4'-diisocyanate Chemical compound C1CC(N=C=O)CCC1CC1CCC(N=C=O)CC1 KORSJDCBLAPZEQ-UHFFFAOYSA-N 0.000 claims description 2
- NIMLQBUJDJZYEJ-UHFFFAOYSA-N isophorone diisocyanate Chemical compound CC1(C)CC(N=C=O)CC(C)(CN=C=O)C1 NIMLQBUJDJZYEJ-UHFFFAOYSA-N 0.000 claims description 2
- 239000005056 polyisocyanate Substances 0.000 claims description 2
- 235000013311 vegetables Nutrition 0.000 claims description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 12
- 238000002156 mixing Methods 0.000 description 10
- 239000000725 suspension Substances 0.000 description 10
- 238000009472 formulation Methods 0.000 description 8
- 238000000034 method Methods 0.000 description 8
- KHIWWQKSHDUIBK-UHFFFAOYSA-N periodic acid Chemical compound OI(=O)(=O)=O KHIWWQKSHDUIBK-UHFFFAOYSA-N 0.000 description 8
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 6
- 239000000835 fiber Substances 0.000 description 6
- 238000002360 preparation method Methods 0.000 description 6
- 239000011780 sodium chloride Substances 0.000 description 6
- 229920001807 Urea-formaldehyde Polymers 0.000 description 5
- 150000001875 compounds Chemical class 0.000 description 5
- ODGAOXROABLFNM-UHFFFAOYSA-N polynoxylin Chemical compound O=C.NC(N)=O ODGAOXROABLFNM-UHFFFAOYSA-N 0.000 description 5
- 229920005989 resin Polymers 0.000 description 5
- 239000011347 resin Substances 0.000 description 5
- HANVTCGOAROXMV-UHFFFAOYSA-N formaldehyde;1,3,5-triazine-2,4,6-triamine;urea Chemical compound O=C.NC(N)=O.NC1=NC(N)=NC(N)=N1 HANVTCGOAROXMV-UHFFFAOYSA-N 0.000 description 4
- 238000012986 modification Methods 0.000 description 4
- 230000004048 modification Effects 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 230000003247 decreasing effect Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- ZXHZWRZAWJVPIC-UHFFFAOYSA-N 1,2-diisocyanatonaphthalene Chemical compound C1=CC=CC2=C(N=C=O)C(N=C=O)=CC=C21 ZXHZWRZAWJVPIC-UHFFFAOYSA-N 0.000 description 2
- -1 99.8%) Chemical compound 0.000 description 2
- 239000005057 Hexamethylene diisocyanate Substances 0.000 description 2
- 229920002522 Wood fibre Polymers 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 125000003172 aldehyde group Chemical group 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- RRAMGCGOFNQTLD-UHFFFAOYSA-N hexamethylene diisocyanate Chemical compound O=C=NCCCCCCN=C=O RRAMGCGOFNQTLD-UHFFFAOYSA-N 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- JQWHASGSAFIOCM-UHFFFAOYSA-M sodium periodate Chemical compound [Na+].[O-]I(=O)(=O)=O JQWHASGSAFIOCM-UHFFFAOYSA-M 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 230000008961 swelling Effects 0.000 description 2
- 238000004448 titration Methods 0.000 description 2
- 229940100445 wheat starch Drugs 0.000 description 2
- 239000002025 wood fiber Substances 0.000 description 2
- PAUHLEIGHAUFAK-UHFFFAOYSA-N 1-isocyanato-1-[(1-isocyanatocyclohexyl)methyl]cyclohexane Chemical compound C1CCCCC1(N=C=O)CC1(N=C=O)CCCCC1 PAUHLEIGHAUFAK-UHFFFAOYSA-N 0.000 description 1
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 description 1
- 229920000945 Amylopectin Polymers 0.000 description 1
- 229920000856 Amylose Polymers 0.000 description 1
- 239000002028 Biomass Substances 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 239000004971 Cross linker Substances 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 239000005058 Isophorone diisocyanate Substances 0.000 description 1
- 244000061456 Solanum tuberosum Species 0.000 description 1
- 235000002595 Solanum tuberosum Nutrition 0.000 description 1
- 241000209140 Triticum Species 0.000 description 1
- 235000021307 Triticum Nutrition 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- CSCPPACGZOOCGX-UHFFFAOYSA-N acetone Substances CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 1
- 239000012773 agricultural material Substances 0.000 description 1
- 239000005030 aluminium foil Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 231100000357 carcinogen Toxicity 0.000 description 1
- 239000003183 carcinogenic agent Substances 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000001143 conditioned effect Effects 0.000 description 1
- 235000005822 corn Nutrition 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000006911 enzymatic reaction Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 150000004676 glycans Chemical class 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002121 nanofiber Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- DGTNSSLYPYDJGL-UHFFFAOYSA-N phenyl isocyanate Chemical compound O=C=NC1=CC=CC=C1 DGTNSSLYPYDJGL-UHFFFAOYSA-N 0.000 description 1
- 239000004848 polyfunctional curative Substances 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
- 239000005017 polysaccharide Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000003755 preservative agent Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000013643 reference control Substances 0.000 description 1
- 238000004513 sizing Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 229920001187 thermosetting polymer Polymers 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J103/00—Adhesives based on starch, amylose or amylopectin or on their derivatives or degradation products
- C09J103/04—Starch derivatives
- C09J103/10—Oxidised starch
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
- B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
- B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
- B27N3/002—Manufacture of substantially flat articles, e.g. boards, from particles or fibres characterised by the type of binder
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
- C08L1/02—Cellulose; Modified cellulose
- C08L1/04—Oxycellulose; Hydrocellulose, e.g. microcrystalline cellulose
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L3/00—Compositions of starch, amylose or amylopectin or of their derivatives or degradation products
- C08L3/04—Starch derivatives, e.g. crosslinked derivatives
- C08L3/10—Oxidised starch
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Adhesives Or Adhesive Processes (AREA)
Abstract
The present invention describes an adhesive composition for wood panel composites, said adhesive composition comprising:oxidized starch;nanocellulose, microfibrillated cellulose or cellulose nanocrystal; isocyanate; andwater.
Description
AN ADHESIVE COMPOSITION FOR WOOD PANEL COMPOSITES
Field of the invention The present invention relates to a biobased adhesive composition for
wood panel composites.
Technical Background
Currently, the wood panel industry uses almost exclusively urea-
formaldehyde (UF) resin. There are major concerns regarding the use of such petroleum-derived thermosetting resins as the formaldehyde has been recently reclassified as a Category 1B carcinogen. The worldwide consumption of UF resins are ca. 12.2 million tons/year on a dry base, and the current UF production has a significant carbon footprint of 200 kg C02- eq/TN panel in production. Besides the massive green gas emission of UF resin, considering the huge overall board production volumes (i.e. 54.7 million m3/year only in Europe) and its utilization in every household and office lead
to the exposure of a tremendous number of people to toxic formaldehyde gas.
New environmental-friendly adhesives can have a substantial impact on the sustainability of this sector. Starch is one of the major polysaccharide polymers that commercially available from biomass and is composed of two types of molecules, amylose and amylopectin. This relatively inexpensive renewable product has been extensively used as coating binder, sizing agent, adhesive, and textile size, however, due to some major drawbacks such as insufficient bonding capacity and poor water resistance, the practical application of starch-based adhesives in wood industries has been limited.
One aim of the present invention is to provide an improved biobased adhesive composition suitable for wood panel composites. Summarv of the invention
The stated purpose above is achieved by an adhesive composition for wood panel composites, said adhesive composition comprising: oxidized starch; nanocellulose, microfibrillated cellulose or cellulose nanocrystal; isocyanate; and
water.
The adhesive composition according to the present invention is a high performance innovative starch-based binder suitable for manufacturing panel boards from wood and/or agricultural materials. The adhesive composition according to the present invention comprises two key compounds being oxidized starch and micro-fibrillated cellulose (approximately 96%), and a small amount of synthetic crosslinker (approximately 4%). The adhesive composition according to the present invention can be used for any type of panel composite manufacturing including plywood, fiberboard, particleboard, oriented-strandboard. lt might also be used for some structural applications under controlled conditions.
Specific embodiments of the invention
Below there is provided some specific embodiments of the present invenfion.
According to one embodiment of the present invention, the amount of the oxidized starch is in the range of 1-80 wt%, preferably in the range of 10- 40 wt%, more preferably 20-30 wt%, based on the total weight of the adhesive composition. Although the broadest range of the amount of the oxidized starch of 1-80 wt% works for the present invention, the best results have been achieved in the range of 20-30 wt%, based on the total weight of the adhesive composition.
According to yet another embodiment of the present invention, the content of the nanocellulose, microfibrillated cellulose or cellulose nanocrystal is in the range of 0.1-10 wt%, preferably in the range of 0.5-3 wt%, based on the total weight of the oxidized starch. Although the broadest range of the content of the nanocellulose, microfibrillated cellulose or cellulose nanocrystal of 0.1-10 wt% works for the present invention, the best results have been achieved in the range of 0.5-3 wt%, based on the total weight of the oxidized starch.
Moreover, according to yet another embodiment of the present invention, the content of isocyanate is in the range of 1-50 wt%, preferably in the range of 1-5 wt%, based on the total weight of the oxidized starch.Although the broadest range of the content of isocyanate of 1-50 wt% works for the present invention, the best results have been achieved in the range of 1-5 wt%, based on the total weight of the oxidized starch.
Furthermore, according to one specific embodiment, the oxidized starch has an aldehyde content range of 5-90%, preferably in the range of 10- 80%. Although the broadest range of the aldehyde content of 5-90% works for the present invention, the best results have been achieved in the range of 10- 80%. ln addition, the isocyanate included according to the present invention may be of different type. Examples are diisocyanate or poly-isocyanate. Furthermore, according to yet another embodiment, the isocyanate - has an NCO-value in the range of 5-95%, preferably 25-50%; and - is selected from diphenylmethane diisocyanate, toluene diisocyanate, methylenebis(phenyl isocyanate) (MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), naphthalene diisocyanate (NDI), methylene bis-cyclohexylisocyanate (HMDl)(hydrogenated MDI), isophorone diisocyanate (lPDl), polybutyl isocyanate (PBI), polymeric diphenylmethane diisocyanate (pMDl), 3-lsopropenyl-d,d-dimethylbenzyl isocyanate (m-TMI), L-Lysine diisocyanate (LDl), or phenyl isocyanate (Pl), or a combination thereof. The NCO-value is achieved by titration of isocyanates according to the ASTM D 2572-97method. Although the broadest range of the NCO-value of 5-95% works for the present invention, the best results have been achieved in the range of 25-50%.
Moreover, also the content of other components may vary. As an example, according to one embodiment of the present invention, the water content is in the range of 20-90%, preferably in the range of 40-80%. Although the broadest range of the water content of 20-90%works for the present invention, the best results have been achieved in the range of 40- 80%.
According to yet another embodiment, the oxidized starch is an oxidation product from a native starch selected from any commercial starch
type, i.e. a starch from cereals or root vegetables, which are generally theorigin of most starches. However, the native starch may include all sources of starch such as corn, wheat, potato, etc.
Moreover, the present invention also refers to the adhesive composition according to the present invention, for use in wood panel composite manufacturing where the wood panel composite is a plywood, fiberboard, particleboard or an oriented-strandboard.
ln line with this, according to one embodiment of the present invention, the wood panel composite is selected from the group consisting of fiberboards, e.g. medium density fiberboard (MDF), high density fiberboard (HDF) and low density fiberboard (LDF).
The type of cellulose used may also be of different type. According to one embodiment of the present invention, the nanocellulose used, such as cellulose nanofibers, microfibrillated cellulose or cellulose nanocrystal, is such that can be prepared from any cellulose source material with mechanical, chemical and enzymatic methods.
Furthermore, also the type of starch and aldehyde content therein is of interest according to the present invention. According to one embodiment, the composition comprises oxidized native wheat starch with an aldehyde content of at least 60%, microfibrillated cellulose, diphenylmethane diisocyanate and water.
Moreover, also additives may be used according to the present invention and as such included in the composition. According to one specific embodiment of the present invention, an additive is included and the additive is selected from one or more of fillers, fire retardants, hydrophobic agents, and preservatives.
Also, a manufacturing method is provided according to the present invention. ln line with this, according to one specific embodiment there is provided a method for manufacturing of an oxidized starch with an aldehyde content of at least 60%, and wherein the method comprises the steps of:
- dispersing native starch in water, preferably in DI water and mixing at temperature ranging from 25 °C to 50 °C;
- adding an oxidant and mixing to form a suspension;- oxidating the suspension at a temperature ranging from 20 °C to 60 °C for a time period ranging from 3 h to 72 h, preferably at 20 °C for 72 h, 35 °C for 24 h, 35 °C for 4 h, or 50 °C for 3 h, wherein a precipitate of the oxidized starch forms.
According to one embodiment, there is provided a method for manufacturing a wood panel composite according to the present invention, wherein the method comprises the steps of:
- an oxidized starch with an aldehyde content of at least 60% is added to dry wood fibers;
- applying a nanocellulose, microfibrillated cellulose or cellulose nanocrystal and an isocyanate to the mixture of the oxidized starch and wood fibers. Moreover, according to one embodiment, the step of applying nanocellulose, microfibrillated cellulose or cellulose nanocrystal and an isocyanate is by spraying.
<\:~._.\..:- .NL-W QE ëwë k xsäzot..
~_ ~ .wßftu (<4 \§\“ \“' ' *\'\*\'\*^' '“\ w '\~'\ \ v' \ \\'\ °\\ \ I \ \\ \ ï\3\..~?\c\.=\\:= \\~'~.: xs-*š Q: å: m? švštsš '
'_. .w -~._.\z._. a säs nat-Pri
Examples and further detailed description Native wheat starch (NWS), sodium periodate (NalO4, 99.8%), sodium
chloride (NaCl, 99.8%), sodium hydroxide, acetone pro analysis, and absolute
ethanol were used for oxidation of starch. Deionized (DI) water with a conductivity of 0.05 i 0.03 us cm* was used for all experiments.
For the preparation of an adhesive according to the present invention, DAS with high aldehyde level; micro-fibrillated cellulose (MFC) with pH of 5-7 from FiberLean (US10,982,387 B2; US10,253,457 B2); an emulsifiablepolymeric diphenylmethane diisocyanate (MDI) with NCO value of 29.6%, a
viscosity of 280 mPa.s, and hydrolysable chlorine s 2000 ppm of were used.
The medium-density fiberboard (MDF) panels were prepared with various
combination levels of compounds. For comparison, commercial melamine-
urea-formaldehyde (MUF) and its hardener (ammonium nitrate) were used.
Step 1. Preparation of dialdehvde starch (DAS) throuqh the oxidation process
NWS was oxidized with NalO4 under completely covered glass bottles
with several layers of aluminium foil, to avoid a light-induced decomposition of
NalO4. Various DAS were synthesized as follow:
a)
b)
d)
f)
DAS_1 was prepared by mixing 1 g of NWS (previously dissolved in DI water at 90 °C for 2h and cooled to room temperature), 1.65 g of NalO4, and 3.85 g of NaCl in 50 mL of DI water to form a suspension. Then, the periodate oxidation was performed at 20 °C for 72 h
DAS_2 was prepared by mixing 1 g of NWS (previously dissolved in DI water at 90 °C for 2h and cooled to room temperature), 1.65 g of NalO4, and 3.85 g of NaCl in 50 mL of DI water to form a suspension. Then, the periodate oxidation was performed at 50 °C for 3 h
DAS_3 was prepared by mixing 1 g of NWS (previously dissolved in DI water at 90 °C for 2h and cooled to room temperature), 0.825 g of NalO4, and 1.925 g of NaCl in 50 mL of DI water to form a suspension. Then, the periodate oxidation was performed at 50 °C for 3 h
DAS_4 was prepared by mixing 1 g of NWS (previously dissolved in DI water at 90 °C for 2h and cooled to room temperature) and 0.825 g of NalO4 in 50 mL of DI water to form a suspension. Then, the periodate
oxidation was performed at 50 °C for 3 h
DAS_5 was prepared by mixing 1 g of NWS (previously dissolved in DI water at 90 °C for 2h and cooled to room temperature) and 1.65 g of NalO4 in 50 mL of DI water to form a suspension. Then, the periodate oxidation was performed at 50 °C for 3 h
DAS_6 was prepared by mixing 1 g of NWS (previously dissolved in DI
water at 90 °C for 2h and cooled to room temperature) and 1.65 g ofNalO4 in 50 mL of Dl water to form a suspension. Then, the periodate oxidation was performed at 50 °C for 3 h g) DAS_7 was prepared by mixing 1 g of NWS and 1.65 g of NalO4 in 50 mL of Dl water to form a suspension. Then, the periodate oxidation was performed at 35 °C for 24 h h) DAS_8 was prepared by mixing 1 g of NWS and 1.65 g of NalO4 in 50 mL of Dl water to form a suspension. Then, the periodate oxidation was performed at 35 °C for 4 h At the end of the oxidation process, the precipitates were washed with water and centrifuged 3 times at 4500 rpm for 10 min, followed by replacing the used water with the fresh one after each centrifugation in order to remove the remaining unreacted reagent. The modification parameters used for the preparation of DAS are shown in Table
Table 1. Modification parameters for DAS preparation
No. Sample NWS Na|O4 NaCl HCI Temperature Time C006 (9) (9) (9) (°C) (h) a DAS_1 1 1.65 3.85 - 20 72 b DAS_2 1 1.65 3.85 - 50 3 c DAS_3 1 0.825 1 .925 - 50 3 d DAS_4 1 0.825 - - 50 3 e DAS_5 1 1.65 - - 50 3 f DAS_6* 1 1.65 - - 50 3 g DAS_7* 1 1.65 - - 35 24 h DAS_8* 1 1.65 - - 35*NWS dispersed in water before oxidation
Characterization of DAS Determination of aldehyde content by titration The aldehyde group content of NWS that were modified at various
conditions is presented in Table 2. lt was shown that aldehyde content decreased with decreasing the reagent (NalO4) content. lncreasing the reaction temperature and time slightly increased the aldehyde content. Thestarch granules that were dispersed in water before oxidation showed comparable or higher aldehyde content with a considerably easier modification process as compared with those disso|ved in water.Table 2. Aldehyde content of DAS polymers
Sample type Aldehyde group content (%) NWS 2.8 i 4.DAS_1 79.6 i 1.DAS_2 81.0 i 2.DAS_3 60.0 i 2.DAS_4 62.4 i 4.DAS_5 79.4 i 5.DAS_6 100.2 i 2.DAS_7 83.3 i 5.DAS_8 79.0 i 4.Based on the aldehyde content results, the DAS_8 was selected for the adhesive preparation due to its relatively high aldehyde content, simple modification and purification processes.
Step 2. Preparation of MDF manufacturinq with an adhesive accordinq to one embodiment of the present invention
Medium-density fiberboard (MDF) panels were manufactured by
standardized procedures that simulated industrial production in the laboratory.
The adhesive according to one embodiment of the present invention was composed of three compounds such as DAS, MFC and MDl. The solid content (SC) of total formulations was adjusted to approximately 25% by adding the required amount of water. For MDF manufacturing with this composition according to the present invention, the dry fibers were first mixed with dry DAS powder (wt DAS/wt dry fiber) for 5 min, and then the MFC and/or the MDl were sprayed on the fibers with different loads for an additional 3 min. Various combination levels of composition compounds were prepared and tested, according to Table 3. Control panel 1 was prepared with 12% of MUF resin.
Table 3. Adhesive formulations for MDF manufacturing
Code Adhesive DAS MFC MDI SC based on SC based on SC based on fiber [%] DAS [%] DAS [%]
Control 1 MUF - - - Control 2* MDI - -DAS DAS_8 12 - - DAS/MFC-0.5 DAS_8 12 0.5 -
DAS/ M FC-1 DAS_8 1 2 1 - DAS/MDI-2 DAS_8 12 - 2 DAS/MFC-
0.5/MDI-2 DAS_8 12 0.5 2 DAS/MFC-
1/MDI-2 DAS_8 12 1 2 DAS/MDI-4 DAS_8 12 - 4 DAS/MFC-
0.5/MDI-4 DAS_8 12 0.5 4 DAS/MFC-
1/MDI-4 DAS_8 12 1MDI-2 - - -
MDI-4 - - - 4 *control 2 was prepared with merely MDI based on the fiber dry weight; SC: solid content
Thereafter, a fiber mat was formed by hand (450 >< 450 mm), cold pre- 5 pressed and then hot-pressed at 200°C. The control boards (control 1 and 2) were hot-pressed at 20 s/mm, while the other panels were followed the step- wise pressing program with a total pressing program of 60 s/mm, as shown in Figure 1. ln brief, the panels were hot-pressed on a maximum pressure of 200 kg/cmz for 20 s/mm, followed by 20 s/mm at half pressure of 100 kg/cmz 10 and finally remained at a no-pressure state for another 20 s/mm.After pressing, the MDF panels were cooled to room temperature, and cut into various test pieces according to the respective standards for evaluating physical and mechanical properties, as described below. Prior to testing, all samples were conditioned for 14 days in a standard climate condition of 65% RH / 20°C.
Properties of MDF panels made from an adhesive accordinq to one
embodiment of the present invention
The manufactured MDF panels were used to evaluate the physical and mechanical properties for each formulation (see Table 3). Internal bond (IB) strength test or tensile strength perpendicular to the surface of panels was conducted following EN 319 (1993) and bending properties, e.g., moduli of rupture (MOR) and elasticity (MOE) were performed according to EN 310 (1993). The water-related properties, e.g., thickness swelling (TS) and water update (WU), of the MDF panels were determined after 2 and 24 h of water soaking, according to EN 317 (1993).
Figure 2 shows the internal bond (IB) strength for the MDF panels as per starch-based formulation. The IB strengths drastically decreased for all MDF panels made with sole DAS or combinations of DAS with MFC or MDI. Only the MDF panel made with the adhesive containing DAS and high levels of MFC and MDI (DAS/MFC-1/MDI-4) showed a comparable IB strength as the control one.
As it was observed in the IB results, the modulus of rupture (MOR) was higher in the MDF panel bonded with DAS and high level of MFC and MDI (DAS/MFC-1/MDI-4) as compared to the reference control panel (Figure 3). The MDF panel produced with the adhesive of DAS/MFC-1/MDI-4 showed a MOR value of 30.4 MPa while the MOR value of the control panel was 23.9 MPa. Except for the panels bonded with the present composition codes of DAS/MFC-1/MDI-2 and DAS/MFC-0.5/MDI-4, all other formulations resulted in lower MOR values than the control one.
The modulus of elasticity (MOE) of the MDF panels has not been considerably affected by adhesive formulations (Figure 4). Except for the panel bonded with DAS and a high level of MFC (DAS/MFC-1), all otherpanels resulted in comparable MOE as the control panel. The MDF panels manufactured with DAS/MFC-1/MDl-4 exhibited the highest MOE value at 3108 MPa, which was considerably higher than that of the control panel, i.e. MOE of the control panel was 2072 MPa.
The thickness swelling (TS) of the MDF panels manufactured with different starch-based formulations are presented in Figure 5. The reference panel showed TS of 20.5% and 23% measured after 2h and 24h, respectively. Only the MDF panels manufactured with DAS, MFC and a higher level of MDl showed comparable TS value as the reference samples after 2 and 24h measuring time. The TS values for the panels bonded with DAS/MFC-0.5/MDl-4 and DAS/MFC-1/MDl-4 adhesive formulations after 24h were respectively 24.0% and 24.2%. Although the presence of MDl has a strong effect on reducing the TS value of the panels, the effect is only obvious when it was used in combination with other compounds, i.e. DAS and MFC.
The water uptake (WU) of the MDF panels bonded with starch-based adhesives after 2 and 24h immersion obviously increased (Figure 6). However, the high WU is not a limiting factor as a threshold value is not
defined in the respective EN standard.
Claims (10)
1. An adhesive composition for wood panel composites, said adhesive composition comprising: oxidized starch; nanocellulose, microfibrillated cellulose or cellulose nanocrystal; isocyanate; and
2. The adhesive composition according to claim 1, wherein the amount of the oxidized starch is if: ïfïç. in the range of 10-40 wt%, more preferably 20-30 wt%, based on the total weight of the adhesive composition.
3. The adhesive composition according to claim 1 or 2, wherein the content of the nanocellulose, microfibrillated cellulose or cellulose nanocrystal is in the range of 0.1 -1 0 wt%, preferably in the range of 0.5-3 wt%, based on the total weight of the oxidized starch.
4. The adhesive composition according to any of claims 1-3, wherein the content of isocyanate is in the range of 1-50 wt%, preferably in the range of 1- 5 wt%, based on the total weight of the oxidized starch.
5. The adhesive composition according to any of claims 1-4, wherein the oxidized starch has an aldehyde content range of 5-90%, preferably in the range of 10-80%.
6. The adhesive composition according to any of claims 1-5, wherein the isocyanate is diisocyanate or poly-isocyanate.
7. The adhesive composition according to any of claims 1-6, wherein the water content is in the range of 20-90%, preferably in the range of 40-80%.
8. The adhesive composition according to any of claims 1-6, wherein the oxidized starch is an oxidation product from a native starch selected from a starch from cereals or root vegetables.
9. The adhesive composition according to any of claims 1-7, wherein the isocyanate - has an NCO-value in the range of 5-95%, preferabiy 25-50%; and - is selected from diphenylmethane diisocyanate, toluene diisocyanate, methy|enebis(pheny| isocyanate) (MDI), toluene diisocyanate (TDI), hexamethyiene diisocyanate (HDI), naphthaiene diisocyanate (NDI), methyiene bis-cyciohexyiisocyanate (HMD|)(hydrogenated MDI), isophorone diisocyanate (IPDI), poiybutyi isocyanate (PBI), poiymeric diphenylmethane diisocyanate (pMDI), 3-|sopropeny|-d,d-dimethy|benzy| isocyanate (m-TMI), L-Lysine diisocyanate (LDI), or pheny| isocyanate (Pl), or a combination thereof.»jiggrïlggggggadhesive composition according to any of claims in wood panel composite manufacturing where the wood panel composite is a plywood, fiberboard, particleboard or an oriented-strandboard.
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| SE2151634A SE545882C2 (en) | 2021-12-29 | 2021-12-29 | An adhesive composition for wood panel composites |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106634688B (en) * | 2017-01-03 | 2018-10-30 | 东北林业大学 | A kind of thermosetting property oxidation modification Cassava starch adhesive and preparation method thereof |
| CN110184004A (en) * | 2019-05-20 | 2019-08-30 | 陈光辉 | A kind of environment-friendly adhesive and preparation method thereof |
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2021
- 2021-12-29 SE SE2151634A patent/SE545882C2/en unknown
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106634688B (en) * | 2017-01-03 | 2018-10-30 | 东北林业大学 | A kind of thermosetting property oxidation modification Cassava starch adhesive and preparation method thereof |
| CN110184004A (en) * | 2019-05-20 | 2019-08-30 | 陈光辉 | A kind of environment-friendly adhesive and preparation method thereof |
Non-Patent Citations (1)
| Title |
|---|
| Jiang, W. et al. "Effect of Cellulose Nanofibrils on the Bond Strength of Polyvinyl Acetate and Starch Adhesives for Wood" In: Bioresources, 2018, Feb., Vol. 13, No. 2, pp. 2283-2292. * |
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