U.S. patent application number 16/543745 was filed with the patent office on 2019-12-05 for algal bio-adhesive.
This patent application is currently assigned to CAMBOND LIMITED. The applicant listed for this patent is CAMBOND LIMITED. Invention is credited to Xiaobin ZHAO.
Application Number | 20190367787 16/543745 |
Document ID | / |
Family ID | 52727162 |
Filed Date | 2019-12-05 |
United States Patent
Application |
20190367787 |
Kind Code |
A1 |
ZHAO; Xiaobin |
December 5, 2019 |
ALGAL BIO-ADHESIVE
Abstract
An algal bio-adhesive comprising algae mass, a crosslinking
agent and an inorganic filler.
Inventors: |
ZHAO; Xiaobin; (Cambridge,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CAMBOND LIMITED |
Cambridge |
|
GB |
|
|
Assignee: |
CAMBOND LIMITED
|
Family ID: |
52727162 |
Appl. No.: |
16/543745 |
Filed: |
August 19, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
15110425 |
Oct 6, 2016 |
10428254 |
|
|
PCT/GB2015/050668 |
Mar 6, 2015 |
|
|
|
16543745 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08G 18/6446 20130101;
C08G 18/73 20130101; C09J 199/00 20130101; C08K 2003/2206 20130101;
C09J 175/04 20130101; C09J 103/02 20130101; B27N 3/02 20130101;
C08G 18/003 20130101; C08G 18/4081 20130101; C08G 18/6484 20130101;
C08L 3/02 20130101; C08G 18/7657 20130101; B27N 3/04 20130101; C08L
99/00 20130101; B27N 3/002 20130101 |
International
Class: |
C09J 199/00 20060101
C09J199/00; B27N 3/00 20060101 B27N003/00; B27N 3/02 20060101
B27N003/02; B27N 3/04 20060101 B27N003/04; C09J 175/04 20060101
C09J175/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 8, 2014 |
GB |
1400267.9 |
Jan 13, 2014 |
CN |
201410013650 |
Jan 27, 2014 |
GB |
1401275.1 |
Claims
1. An algal bio-adhesive comprising algae mass, a crosslinking
agent and an inorganic filler.
2. The algal bio-adhesive according to claim 1, comprising a
defoaming agent.
3. The algal bio-adhesive according to claim 1, comprising: 20 to
60% by weight solid content, and 40 to 80% by weight liquid
content, in which the solid content comprises: 50 to 89% by weight
of algae mass; 1 to 20% by weight of a crosslinking agent; and 10
to 30% by weight of inorganic filler.
4. The algal bio-adhesive according to claim 3, in which the liquid
content comprises water, and optionally 0.01 to 5% by weight of a
defoaming agent.
5. The algal bio-adhesives according to claim 1, wherein the algae
mass comprises at least one of blue-green algae, red algae, and
brown algae, which can be harvested from river and ocean.
6. The algal bio-adhesives according to claim 1, wherein the algae
mass comprises algae cultivated in at least one of a pond or
photobioreactor.
7. The algal bio-adhesives according to claim 1, wherein the algae
mass comprises genetically modified or enhanced or selected algae
cultivated in a pond or photobioreactor.
8. The algal bio-adhesives according to claim 1, wherein the algae
mass has a water content less than 70%, preferably less than 40%,
most preferably less than 20%.
9. The algal bio-adhesives according to claim 1, wherein the algae
mass is from a biodiesel process by-product of algae.
10. The algal bio-adhesives according to claim 1, wherein the
crosslinking agent is selected from the group consisting of: at
least one synthetic polymeric crosslinking agent; at least one
inorganic material; and a mixture of at least one synthetic
polymeric crosslinking agent and at least one inorganic
material.
11. The algal bio-adhesives according to claim 10, in which the
synthetic polymeric crosslinking agents are selected from the group
consisting of: polyisocyanates, polyisocyanates with blocked
isocyanate groups and epoxy resins; and the inorganic materials are
selected from the group consisting of: silicates and borates.
12. The algal bio-adhesives according to claim 1, wherein the
filler comprises at least one calcium compound selected from the
group consisting of: calcium oxide, calcium sulfate, calcium
carbonate and calcium hydroxide.
13. The algal bio-adhesives according to claim 1, comprising at
least one additive selected from the group consisting of: at least
one defoaming agent, at least one wet strength agent, at least one
thickener and at least one crosslinking agent.
14. A method for preparing algal bio-adhesives according to claim
1, comprising the steps of: a. combining algal mass, a
cross-linking agent, and fillers to form a blend using a mechanical
mixer or blender, b. milling the blend via a micronization milling
machine or any other chosen mechanical milling machine to produce
powdery material with particle size between 30-500 .mu.m,
preferably, between 30-250 .mu.m, most preferably 30-125 .mu.m, c.
mixing the powdery material with water, optionally with addition of
other additives.
15. The method according to claim 14, wherein the blend consists
50-89% of the algal mass, 1.0-20% of crosslinking agent and 10-30%
of fillers.
16. The method according to claim 14, in which the percentage of
each additive used to form aqueous bio-adhesives is between
0.01-5%, preferably 0.1-5%.
17. The method according to claim 14, wherein the additives
comprise at least one defoaming agent which is: a silicone-based
defoaming agent; a polyether based defoaming agent; a higher
alcohol defoaming agent; or a food grade defoaming agent, such as
mineral oil, vegetable oil or white oil based defoaming agent.
18. The method according to claim 14, wherein the additives
comprise at least one thickener which is a water soluble natural
polymer such as cellulose derivatives, proteins, alginate and
chitosan.
19. The method according to claim 14, wherein the additives
comprise a wet strength agent which is
polyamideamine-epichlorohydrin (PAE).
20. The method according to claim 14, wherein the crosslinking
agent is a polymeric isocyanate with the isocyanate group
blocked.
21. The method according to claim 14, in which the algal
bio-adhesive has a solid content between 20-60%, preferably 20-50%,
most preferably 20-40%.
22. The algal bio-adhesive according to claim 1, for use in at
least one application selected from the group consisting of: wood
panel process as substitute of formaldehyde based wood adhesives;
water-resistant glue for paper packaging industry; and hospital and
school building board decoration, assembling and construction.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of priority under 35 USC
.sctn. 120 of U.S. patent application Ser. No. 15/110,425, filed on
Oct. 6, 2016, which is a U.S. national phase application based on
PCT/GB2015/050668 under 35 USC .sctn. 371, filed on Mar. 6, 2015,
the contents of which are incorporated herein by reference in their
entireties.
DESCRIPTION 1
Field of Invention
[0002] This invention concerns novel water-resistant and versatile
adhesive products and glue derived from grain-based ethanol
production byproducts including CDS (condensed distiller's
solubles), DDG (Distiller's Dried Grain), DDGS (Distiller's Dried
Grains and Solubles) and WDG (Wet Distiller's Grain) materials. In
this patent, the term Distiller's Grain (DG) is used in general. In
particular, the processed DG bio-adhesives according to this
invention have strong dry and wet strength and are thus useful as
formaldehyde-free wood adhesive to replace currently used
formaldehyde based wood adhesives. The invention further relates to
DG-derived glues and adhesive products containing a cross-linked
network which can be further processed into powder form to become
adhesive gel or aqueous glue.
Background Art and Related Disclosures
[0003] Due to the inherently finite nature of fossil fuel
resources, the world faces the challenge of finding suitable
renewable substitutes that can begin to replace petrochemicals both
as a source of energy and as a source of materials for plastics,
rubbers, fertilizers, and fine chemicals. More recently, biofuels
have been endorsed as a key component of national and international
strategies to reduce greenhouse gas (GHG) emissions and mitigate
potential climate change effects.
[0004] Two biofuels, ethanol (ethyl alcohol) and biodiesel from
fatty acid methyl esters account for the vast majority of global
biofuel production and use today. These biofuels are made primarily
from agricultural commodities, such as grain and sugar cane beet
molasses, cassava, whey, potato and food or beverage waste for
ethanol and vegetable oil for biodiesel.
[0005] In 2010, approximately 87 billion litres (23 billion
gallons) of ethanol were produced, with the United States, Brazil,
and the European Union accounting for 93% of this output (RFA,
2011a), which leaves large quantities of DG byproducts, mainly used
for animal feeds.
[0006] Two processes are primarily used to make ethanol from
grains: dry milling and wet milling. In the dry milling process,
the entire grain kernel typically is ground into flour (or "meal")
and processed without separation of the various nutritional
component of the grain. The flour is slurred with water to form a
"mash". Enzymes are added to the mash, which is then processed in a
high-temperature cooker, cooled and transferred to fermenters where
yeast is added and the conversion of sugar to ethanol begins. After
fermentation, the resulting ethanol containing mixture "beer" is
transferred to distillation columns where the ethanol is separated
from the residual "stillage". The stillage is sent through a
centrifuge that separates the solids from the liquids. The liquids,
or solubles, are then concentrated to a semi-solid state by
evaporation, resulting in condensed distiller's solubles (CDS) or
"syrup". CDS is sometimes sold direct into the animal feed market,
but more often the residual coarse grain solids and the CDS are
mixed together and dried to produce distiller's dried grain with
solubles (DDGS). In the cases where the CDS is not re-added to the
residual grains, the grain solids product is simply called
distiller's dried grain (DDG). If the distiller's grain is being
fed to livestock in close proximity to the ethanol production
facility, the drying step can be avoided and the product is called
wet distiller's grain (WDG). Because of various drying and syrup
application practices, there are several variants of distiller's
grain (one of which is called modified wet distiller's grain), but
most product is marketed as DDGS, DDG or WDG. Some dry-mill ethanol
plants in the United States are now removing crude maize oil from
the CDS or stillage at the back end of the process, using a
centrifuge. The maize oil is typically marketed as an individual
feed ingredient or sold as a feedstock for further processing (e.g.
for biodiesel production). The co-product resulting from this
process is known as "oil extracted" DDGS or "de-oiled" DDGS. These
co-products typically have lower fat content than conventional
DDGS, but slightly higher concentrations of protein and other
nutrients. A very small number of dry-mill plants also have the
capacity to fractionate the grain kernel at the front end of the
process, resulting in the production of germ, bran, "high-protein
DDGS" and other products (RFA, 2011b). In some cases, ethanol
producers are considering using the cellulosic portions of the
maize bran as a feedstock for cellulosic ethanol. The majority of
grain ethanol produced around the world today comes from the dry
milling process. In the wet milling process, shelled maize is
cleaned to ensure it is free from dust and foreign matter. Next,
the maize is soaked in water, called "steepwater", for between 20
and 30 hours. As the maize swells and softens, the steepwater
starts to loosen the gluten bonds with the maize, and begins to
release the starch. The maize goes on to be milled. The steepwater
is concentrated in an evaporator to capture nutrients, which are
used for animal feed and fermentation. After steeping, the maize is
coarsely milled in cracking mills to separate the germ from the
rest of the components (including starch, fibre and gluten). Now in
a form of slurry, the maize flows to the germ separators to
separate out the maize germ. The maize germ, which contains about
85% of the maize's oil, is removed from the slurry and washed. It
is then dried and sold for further processing to recover the oil.
The remaining slurry then enters fine grinding. After the fine
grinding, which releases the starch and gluten from the fibre, the
slurry flows over fixed concave screens which catch the fiber but
allow the starch and gluten to pass through. The starch-gluten
suspension is sent to the starch separators. The collected fibre is
dried for use in animal feed. The starch-gluten suspension then
passes through a centrifuge where the gluten is spun out. The
gluten is dried and used in animal feed. The remaining starch can
then be processed in one of three ways: fermented into ethanol,
dried for modified maize starch, or processed into maize syrup. Wet
milling procedures for wheat and maize are somewhat different. For
wheat, the bran and germ are generally removed by dry processing in
a flour mill (leaving wheat flour) before steeping in water.
[0007] In 2010, an estimated 142.5 million tonnes of grain was used
globally for ethanol (F. O. Licht, 2011), representing 6.3% of
global grain use on a gross basis. Because roughly one-third of the
volume of grain processed for ethanol actually was used to produce
animal feed, it is appropriate to suggest that the equivalent of 95
million tonnes of grain were used to produce fuel and the remaining
equivalent 47.5 million tonnes entered the feed market as
co-products. Thus, ethanol production represented 4.2% percent of
total global grain use in 2010/11 on a net basis. The United States
was the global leader in grain ethanol production, accounting for
88% of total grain use for ethanol. The European Union accounted
for 6% of grain use for ethanol, followed by China (3.4%) and
Canada (2.3%). The vast majority of grain processed for ethanol by
the United States was maize, though grain sorghum represented a
small share (approximately 2%). Canada's industry primarily used
wheat and maize for ethanol, while European producers principally
used wheat, but also processed some maize and other coarse grains.
Maize also accounted for the majority of grain use for ethanol in
China.
[0008] There is huge existing market of wood glue for wood panel
industry. Organic polymers of either natural or synthetic origin
are the major chemical ingredients in all formulations of wood
adhesives. Urea-formaldehyde is the most commonly used adhesive,
which can release low concentrations of formaldehyde from bonded
wood products under certain service conditions. Formaldehyde is a
toxic gas that can react with proteins of the body to cause
irritation and, in some cases, inflammation of membranes of eyes,
nose, and throat. It is a suspected carcinogen, based on laboratory
experiments with rats.
[0009] Phenol-formaldehyde adhesives, which are used to manufacture
plywood, flakeboard, and fiberglass insulation, also contain
formaldehyde. However, formaldehyde is efficiently consumed in the
curing reaction, and the highly durable phenol-formaldehyde,
resorcinol-formaldehyde, and phenol-resorcinol-formaldehyde
polymers do not chemically break down in service to release toxic
gas. However, it uses the petroleum-based resource and also
expensive.
[0010] Increasing environmental concerns and strict regulations on
emissions of toxic chemicals have forced the wood composites
industry to develop environmentally friendly alternative adhesives
from abundant renewable substances such as soybean protein, animal,
casein, vegetable, and blood. Also, adhesives from lignin, tannin,
and carbohydrates have been studied for replacement of synthetic
adhesives that are dominatingly used in the manufacture of wood
composite products. These adhesives are generally used for
non-structural applications, due to their poor water resistance and
low strength properties.
[0011] Modifications including further purification to obtain high
protein contents, increases of the specific surface area of the
materials, denaturation of the protein by acid, alkaline and
surfactants have been shown to be useful to enhance the wood
adhesive strength of soy based glue, or mixed with other synthetic
adhesives such as phenol formaldehyde resin which increase the cost
for manufacturing.
[0012] It would, therefore, be advantageous to provide renewable
bio-adhesives which are able to be used as wood adhesives with
comparable strength as the synthetic wood adhesives such as
formaldehyde based glue.
[0013] It is, therefore, a primary objective of the present
invention to provide a stable adhesive generally inexpensive and
versatile.
[0014] It is, therefore, a further object of the present invention
to provide a stable aqueous adhesive comprising DG-material derived
from ethanol production, and that are safe, water-resistant for
wood application. The DG materials include DDGS, CDS, DDG and WDG
from byproducts of ethanol production plant.
[0015] It is a further object of the present invention to prepare
DG based adhesive products that are produced by mixing dry DG
materials with additives and further milled into fine powder for
greater adhesive strength properties to broaden their suitability
for adhesive applications, easy in storage for longer shelf-life
and transportation.
[0016] It is yet a further objective of the invention to prepare DG
based adhesive products that are produced by mixing dewatered DG
materials, e.g. WDG and CDS (water content less than 70%) with
additives and homogenised into aqueous bio-adhesives.
[0017] It is yet a further object of the invention to prepare an
adhesive that consists essentially of byproducts of after ethanol
distillation during ethanol biofuel process.
[0018] It is yet another object of the invention to prepare
adhesive products that comprise naturally DG materials in dry form
(e.g. DDGS and DDG) that are blended with a crosslinking agent to
form a crosslinked network to enhance the water resistance of the
adhesives.
[0019] It is further another object of the invention to mill the
above mixture to greater than 80 meshes for formulation into
aqueous adhesives.
[0020] It is yet another objective of the invention to prepare
adhesive products that comprise above aqueous adhesives and a
crosslinking agent and/or wet-strengthen agent for water-resistant
wood industry application.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The current invention concerns novel bio-adhesives derived
from DG materials.
[0022] According to a first aspect of the invention there is
provided DG based bio-adhesives consisting of DG mass, crosslinking
agents and inorganic fillers, optionally other additives for making
aqueous DG bio-adhesives.
[0023] According to a second aspect of the invention there is
provided a process for manufacturing such DG based bio-adhesives,
the process comprising the steps of: [0024] a. Combining DG
material obtained directly from ethanol production plant, such as
DDGS, DDG, CDS and WDG with defined dryness and suitable protein
content, a cross-linking agent, and fillers to form a blend using a
mechanical mixer or blender, [0025] Whereas in step a: the DG
material has the water content less than 70%; preferably less than
40%; most preferably less than 20%;
[0026] the crosslinking agent is selected from a organic polymeric
material with crosslinkable groups such as poly-isocyanate, epoxy
resin, or an inorganic material such as silicates, borates or
mixture of polymeric crosslinker and the inorganic substance;
[0027] the fillers are calcium materials such as calcium oxide,
calcium hydroxide, calcium chloride, calcium carbonate, calcium
sulfate, preferably calcium oxide, calcium sulfate which can
dewater during the blending process. The DG material in the blend
has the content between 50-89%, crosslinking agent has 1.0-20%, and
fillers are 10-30%. [0028] b. Milling the blend via a micronisation
milling machine or any other chosen mechanical wet or dry milling
machine to produce fine powdery material with particle size between
80-600 meshes, preferably, between 100-500 meshes, most preferably
200-300 meshes. [0029] c. Mixing the powdery material with
additional water, optionally with addition of a defoamer or an
anti-foaming agent, a thickener and optionally with a crosslinking
agent or wet-strength agent, wherein defoamer is selected from food
grade deformer used in milk, protein process industry, such as
mineral oil, vegetable oil or white oil based deforming agent; the
thickener selected are food grade water soluble natural polymer
such as cellulose derivatives e.g. HPMC, CMC, proteins such as
gelatin, alginate, chitosan; and water soluble polymers such as
Polyvinyl alcohol (PVA), sodium polyacrylic acid (PAA) or it's
copolymer. The wet strength agent is polyamideamine-epichlorohydrin
(PAE), the crosslinking agent is a polymeric isocyanate or
polymeric isocyanate with the isocyanate group blocked to obtain DG
aqueous bio-adhesives with solid content between 20-60%, preferably
20-50%, most preferably 20-40%.
[0030] According to the invention there is provided a process for
manufacturing DG based bio-adhesives, the process comprising the
steps of: [0031] a. combining DG material, a cross-linking agent
and inorganic fillers to form a blend by mechanical blender; [0032]
b. Micronising or mechanical milling the blend to obtain powdery
material; and [0033] c. Mixing the powdery material with additional
water, optionally with the addition of other additives such as
defoaming agent, thickener, wet strength agent and a crosslinking
agent to form DG based bio-adhesives.
[0034] DG biomass contains lipids, proteins, and carbohydrates that
mainly is used for animal feed. Compared to soy meal, the protein
content is ranged from 20-40% depending on the process of the
byproduct. Typically for DDGS, the protein content is between
20-30%. Due to the nature of the origin, the cost of DG is much
lower than that of soy meal. For example, the price of DDGS is
about 1/2-1/3 of the price of soy flower.
[0035] Surprisingly it was found that DG containing 20-30% protein
(dry mass) without further expensive refining to increase the
protein content can be used for the current process to produce
bio-adhesives. The DG biomass is the by-products directly from
ethanol production plant, which are readily available as animal
feed material, including CGS, DDG, DDGS and WDG. The quantity
required for the formulation can be adjusted according to the
protein content and the solid content of the mass.
[0036] The crosslinking agent used in current invention is
polymeric isocyanate which is used to produce polyurethane. The
polyisocyanate functional groups used in current invention include
PMDI, PHDI, Polyurethane pre-polymer, blocked polyisocyanates such
as polyisocyanates with phenol, .epsilon.-caprolactam blocked. A
blocked polyisocyanate can be defined as an isocyanate reaction
product which is stable at room temperature but dissociates to
regenerate isocyanate functionality under the influence of heat
around 100-250.degree. C. Blocked polyisocyanates based on aromatic
polyisocyanates dissociate at lower temperatures than those based
on aliphatic ones. The dissociation temperatures of blocked
polyisocyanates based on commercially utilized blocking agents
decrease in this order:
alcohols>.epsilon.-caprolactam>phenols>methyl ethyl
ketoxime>active methylene compounds.
[0037] Other crosslinking agent can be used in current invention
include epoxy-resins. Epoxy resins, also known as polyepoxides are
a class of reactive prepolymers and polymers which contain epoxide
groups. Epoxy resins are polymeric or semi-polymeric materials and
An important criterion for epoxy resins is the epoxide content.
This is commonly expressed as the epoxide number, which is the
number of epoxide equivalents in 1 kg of resin (Eq./kg), or as the
equivalent weight, which is the weight in grams of resin containing
1 mole equivalent of epoxide (g/mol). One measure may be simply
converted to another:
Equivalent weight(g/mol)=1000/epoxide number(Eq./kg)
[0038] The epoxy resin can be used in current invention include
Bisphenol A epoxy resin, Bisphenol F epoxy resin, Aliphatic epoxy
resin and Glycidylamine epoxy resin.
[0039] The content of the polymeric crosslinking agent mixed with
DG materials is between 1.0-20%.
[0040] Other crosslinking agents can be used include inorganic
materials such as silicates and borates which can be used
separately or mixed with above polymeric crosslinking agent.
[0041] The total content is in the range of 1.0-20%, preferably in
the range of 1-10%, most preferably in the range of 5-10%.
[0042] The fillers used for current application are calcium based
inorganic materials. They can be used to adjust the water content
of the DG materials and the reheological properties of the final
bio-adhesives. They can also be useful to help the subsequent dry
milling process.
[0043] The more calcium materials are incorporated, the more dry
blend can be obtained. The typical content of the calcium materials
such as single calcium oxide, calcium chloride calcium carbonate
and calcium sulfate or their mixtures is in the range of 10-30%.
The optimised composition for easy to dry mill can be adjusted by
changing the ratio of DG mass and the fillers.
[0044] After the blending with an industrial mechanical blender,
the mixture needs to be stored for overnight (>8 hrs) before
milling. The fine powder will give a homogenized mixture in order
to swell in water to form bio-adhesives for easy to spray or spread
for applications.
[0045] The milling process can be performed by readily available
micronisation equipments, or mechanical milling machines. The
particle size obtained is controlled at 80-600 meshes, preferably
at 100-500 meshes, most preferably at 200-300 meshes. When WDG is
used, the milling can be achieved by homogenization process, which
can directly lead to final aqueous bio-adhesives.
[0046] The DG bio-adhesives can be formulated by adding above
milled powder into premeasured water in a batch vessel with a mixer
or pumping into a mechanical static mixer with calculated amount of
water, or into a batch homogeniser or online homogeniser for
continuous formulation of the aqueous bio-adhesives.
[0047] The solid content of the formed bio-adhesives is between
20-50% and preferably between 20-40%.
[0048] Optionally, in the formulation of the aqueous bio-adhesives,
some additives can be added for easy manufacturing, optimized
viscosity and enhanced wet strength for applications.
[0049] The additives include defoamer or an anti-foaming agent, a
thickener and optionally with a crosslinking agent or wet-strength
agent, wherein defoamer is selected from food grade deformer used
in milk, protein process industry, such as mineral oil, vegetable
oil or white oil based deforming agent; the thickener selected are
food grade water soluble natural polymer such as cellulose
derivatives e.g. HPMC, CMC, proteins such as gelatin, alginate,
chitosan etc; or water soluble hydrogel such as PVA, PAA and PAA
copolymer, the wet strength agent is polyamideamine-epichlorohydrin
(PAE), the crosslinking agent is a polymeric isocyanate or a
polymeric isocyanate with the isocyanate group blocked. The
percentage of the additives considered to be added is in the range
of 0.01-5%, preferably in the range of 0.1-5%, most preferably in
the range of 0.5-5%.
[0050] The main application of current invention of DG
bio-adhesives is in the field of production of wood based panels to
replace formaldehyde based wood adhesives. The wood based panels
include plywood, fibreboard and particle board.
[0051] The DG bio-adhesives can also be used for making paper-based
board such as paper packaging board, cardboard, carton packaging
material for recyclable food packaging, gift packaging and medical
packaging. Other applications include adhesives for furniture used
in hospital and school. The bio-adhesives can also be used to make
fibreboard based on non-wood materials such as straw. The straw
based fibreboard can be used as packaging materials for food. The
DG bio-adhesives can also be used in marine board whereas the
highly water-resistant wood board is required. Although the
invention has been described in connection with specific preferred
embodiments, it should be understood that the invention as claimed
should not be unduly limited to such specific embodiments, various
applications of the described modes of carrying out the invention
which are obvious to those skilled in the art are intended to be
covered by the present invention.
[0052] The invention now will be further exemplified.
Example 1: Preparation of DDGS Based Bio-Adhesive
[0053] DDGS, water content 10%, protein content 26%, lipid content
5%, was from USA. In a mechanical blender (250 KG volume capacity),
50 kg of the DDGS, 10 kg of calcium oxide powder (200 meshes) and
10 kg of sodium silicate was added and mixed for 30 mins and stored
for 4 hours. To the mixture, 2 kg of PMDI was slowly added during
mixing within 20 mins and blended for further 30 mins to obtain a
well mixed blend. The blend was sealed and stored overnight for 10
hours, and then transferred to an Air-Jet milling machine to obtain
fine powder with particle size around 300 meshes. In a 500 L
high-shear mixing vessel for producing coating material, 100 L
water was added, and then 50 kg of above milled powder was added
and mixed for 60 mins. 1 Kg PVA powder (1788) was added and mixed
for another 60 mins. 100 g of defoaming agent was added to obtain
the DDGS bio-adhesives ready for plywood process. The solid content
is about 33%.
[0054] Application of DDGS Bio-Adhesives for Plywood:
[0055] 5 pieces of poplar veneers were cut into size at 36
cm.times.36 cm. The above algal bio-adhesive was brushed onto one
side of the first piece, one side of the last piece and the two
sides of the rest of 3 pieces. Amount of bio-adhesives on each
veneer was controlled with a balance. 5 pieces of poplar veneers
were cross-staged. Assembled wood specimens were pressed at 3 MPa
and 120.degree. C. for 10 min or 150.degree. C. for 5 min with a
hot press. The wood assemblies were conditioned at 23.degree. C.
and 50% RH for 48 h and then cut into five pieces with overall
dimensions of 80.times.20 mm and glued dimensions of 20.times.20
mm.
[0056] The cut wood specimens were conditioned for 4 additional
days at the same conditions before testing. Shear strength testing
was performed using an Instron (Model 4465; Canton, Mass., USA) at
a crosshead speed of 1.6 mm/min according to ASTM Standard Method
D906-98(2011). Shear strength, including dry strength and wet
strength, ware performed following ASTM Standard Methods (ASTM
D906-98 2011) at maximum load was recorded. Values reported are the
average of five specimen measurements.
[0057] Water resistance test: Specimen was boiled at 100.degree. C.
for 2 hours. The specimen is removed from water and visually
inspected for evidence of dismemberment.
[0058] Comparison of Urea-Formaldehyde (UF) glue and
Phenol-Formaldehyde (PF) glue to make plywood: Commercially UF and
PF for pressing plywood were carried out as the method shown in
Example 1.
Example 2: Preparation of DDGS Based Bio-Adhesive
[0059] DDGS, water content 10%, protein content 26%, lipid content
5%, was from USA. In a mechanical blender (250 KG volume capacity),
50 kg of the DDGS, 10 kg of calcium oxide powder (200 meshes) and
10 kg of sodium silicate was added and mixed for 30 mins and stored
for 4 hours. To the mixture, 2 kg of PMDI was slowly added during
mixing within 20 mins and blended for further 30 mins to obtain a
well mixed blend. The blend was sealed and stored overnight for 10
hours, and then transferred to an Air-Jet milling machine to obtain
fine powder with particle size around 300 meshes. In a 500 L
high-shear mixing vessel for producing coating material, 150 L
water was added, and then 50 kg of above milled powder was added
and mixed for 30 mins. To the mixture, 12.5 kg of PAE and 2.5 kg of
PMDI was added and mixed for 60 mins. 100 g of defoaming agent was
added to obtain the algal bio-adhesives ready for plywood process.
The solid content is about 30%. The plywood using above DDGS
bio-adhesive was produced according to the same method as example
1.
Example 3: Preparation of DDGS Based Bio-Adhesive
[0060] DDGS, water content 10%, protein content 26%, lipid content
5%, was from USA. In a mechanical blender (250 KG volume capacity),
50 kg of the DDGS, 10 kg of calcium oxide powder (200 meshes) and
10 kg of sodium silicate was added and mixed for 30 mins and stored
for 4 hours. To the mixture, 2 kg of PMDI was slowly added during
mixing within 20 mins and blended for further 30 mins to obtain a
well mixed blend. The blend was sealed and stored overnight for 10
hours, and then transferred to an Air-Jet milling machine to obtain
fine powder with particle size around 300 meshes. In a 500 L
high-shear mixing vessel for producing coating material, 100 L
water was added, and then 50 kg of above milled powder was added
and mixed for 60 mins. To the mixture, 5.0 kg of PMDI was added and
mixed for 60 mins. 100 g of defoaming agent was added to obtain the
algal bio-adhesives ready for plywood process. The solid content is
about 35%. The plywood using above DDGS bio-adhesive was produced
according to the same method as example 1.
Example 4: Preparation of CDS Based Bio-Adhesive
[0061] CDS was obtained commercially from ethanol production
manufacturer. The water content is about 20%, protein content 30%.
To a 100 L blender, 10 kg of the CDS, 2 kg of calcium oxide powder
(200 meshes) and 1 kg of sodium silicate was added and mixed for 30
mins. To the mixture, 1 kg of PMDI was slowly added during mixing
within 20 mins and blended for further 30 mins to obtain a well
mixed blend. The blend was sealed and stored overnight for 10
hours, and then transferred to an Air-Jet milling machine to obtain
fine powder with particle size around 300 meshes. In a 100 L
high-shear mixing vessel for producing coating material, 40 L water
was added, and then 10 kg of above milled powder was added and
mixed for 30 mins. To the mixture, 1.0 kg of PMDI was added and
mixed for 60 mins. 100 g of defoaming agent was added to obtain the
algal bio-adhesives ready for plywood process. The solid content is
about 20%.
[0062] The plywood using above WDG bio-adhesive was produced
according to the same method as example 1.
Example 5: Preparation of WDG Based Bio-Adhesive
[0063] WDG was obtained commercially from ethanol production
manufacturer. The water content is about 70%, protein content 10%.
In a 100 L high-shear homogenizer for producing coating material,
40 L WDG was added, and to the mixture, 2 Kg sodium silicate, 1 Kg
PVA(1788) and 1.0 kg of PMDI was added one by one and homogenised
for 60 mins. 100 g of defoaming agent was added to obtain the WDG
bio-adhesives ready for plywood process. The solid content is about
28%.
[0064] The plywood using above WDG bio-adhesive was produced
according to the same method as example 1.
Example 6: Application of DG Bio-Adhesives for Preparation of
Particle Board
[0065] DG bio-adhesive produced in example 2 was used to prepare
particle board. 150 g of DG bio-adhesive was added slowly to 600 g
of pine wood particles having a moisture content of approximately
5% and mixed with a mechanical mixer. A 9-inch.times.9 inch.times.9
inch wood forming box was centered on a 12 inch.times.12
inch.times.0.1 inch stainless steel plate, which was covered with
aluminum foil. The wood-adhesive mixture is slowly added into the
forming box to achieve a uniform density of particles coated with
bio-adhesive. The mixture was compressed by hand with a plywood
board and the wood forming box was carefully removed so that the
particle board matte would not be disturbed. Then, the plywood
board was removed, a piece of aluminum foil was placed on the
matte, and another stainless steel plate was placed on top of the
matte. The particle board matte was then pressed to a thickness of
3/4 inch using the following conditions: 120 psi for 10 Ominutes at
a press platen temperature of 170.degree. C. The particle board was
trimmed to 5 inches.times.5 inches to check the water resistant
property.
Example 7: Application of DG Bio-Adhesives for Preparation of Fiber
Board
[0066] DG bio-adhesive produced in example 3 was used to prepare
fiber board. 200 g of DG bio-adhesive was sprayed slowly to 800 g
of pine wood fiber having a moisture content of approximately 5%
while mixing with a mechanical mixer. A 9-inch.times.9 inch.times.9
inch wood forming box was centered on a 12 inch.times.12
inch.times.0.1 inch stainless steel plate, which was covered with
aluminum foil. The wood-adhesive mixture is slowly added into the
forming box to achieve a uniform density of fibers coated with
bio-adhesive. The mixture was compressed by hand with a plywood
board and the wood forming box was carefully removed so that the
fiber board matte would not be disturbed. Then, the plywood board
was removed, a piece of aluminum foil was placed on the matte, and
another stainless steel plate was placed on top of the matte. The
fiber board matte was then pressed to a thickness of 3/4 inch using
the following conditions: 120 psi for 10 minutes at a press platen
temperature of 170.degree. C. The fiber board was trimmed to 5
inches.times.5 inches to check the water resistant property.
TABLE-US-00001 TABLE 1 Test results of plywood produced from algal
bio-adhesives in example 1-7 Water resistance test Dry strength Wet
strength (boiling water for two Plywood (MPa) (MPa) hours) Example
1 1.8 0.8 Intact Example 2 3.0 1.8 Intact Example3 2.5 1.3 Intact
Example 4 2.5 1.2 Intact Example 5 3.0 1.5 Intact Example 6 / /
Intact Example 7 / / Intact Formaldehyde-Urea 2.5 / Dismemberment
resin Phenol-Urea resin 3.4 1.8 intact
DESCRIPTION 2
[0067] The present invention is related to a distiller's grain
based reinforced material and its use as a distiller's grain based
non-formaldehyde glue for wood panel applications. Distiller's
Grain-based reinforced material for wood-based panels and
Distiller's Grain-based non-formaldehyde adhesive prepared from
Distiller's Grain-based reinforced material.
[0068] The invention relates to a distiller's grain-based
reinforced material for wood-based panels and a distiller's
grain-based non-formaldehyde adhesive prepared from the distiller's
grain-based reinforced material. The distiller's grain-based
reinforced material is a powdery product obtained by stirring,
curing and milling the following components by weight percent: 50%
to 90% of distiller's grain, 10% to 35% of an inorganic material
and 1% to 20% of a high-molecular water-resistant material. The
distiller's grain can be one or more of DDGS (Distillers Dried
Grains with Soluble), DDG (Distillers Dried Grains) and DDS
(Distillers Dried Soluble). The distiller's grain-based
non-formaldehyde adhesive is prepared by stirring and mixing the
following components by weight percent: 20% to 50% of the
distiller's grain-based reinforced material, 0.1% to 5% of additive
and water to make up the rest. The distiller's grain-based
non-formaldehyde adhesive prepared from the distiller's grain-based
reinforced material really realizes the purpose of non-formaldehyde
release and can be used for overcoming the defects of high raw
material cost, easy deterioration and poor water resistance of the
existing biological adhesive. The bonding strength and the water
resistance of the distiller's grain-based non-formaldehyde adhesive
reach or exceed those of the existing urea-formaldehyde adhesive
and the existing phenol adhesive. Thus, the distiller's grain-based
reinforced material can be used to prepare various types of
wood-based panels.
BACKGROUND
[0069] The main wood-based panels have four categories including
plywood, particle board, block board and fibreboard. Except the
manufacturing of plywood used for the construction mould panels
where phenol-formaldehyde resin is used, the mostly wood panels are
manufactured using urea-formaldehyde or melamine modified
urea-formaldehyde glue. Therefore, contaminated wood-based panels
are mainly due to the release of formaldehyde from the adhesives.
In order to solve the problem of formaldehyde contamination, new
greener formaldehyde-free adhesives with low-cost and easy adoption
by industry has to be researched and developed. In both China and
the world, soy based formaldehyde-free biological glue and starch
based glue have been developed. However, there are some
disadvantages such as the high prices of raw materials, low bonding
strength, poor water resistance and less resistance to microbial
degradation. Although the performance can be improved through
modification process of the biological glue, the production cost
has increased. In addition, the viscosity of soybean biological
glue is very high, which leads to the suitability problems in the
industrial process of wood based panel. For starch based biological
glue, although the price is lower than soy based biological glue,
it has poor water resistance and does not apply to Class 1, II and
III plywood.
DETAILED DESCRIPTION OF THE INVENTION
[0070] The first objective of the present invention is to provide a
Distiller's grain-based reinforced material for wood-based panels,
with widely available sources of raw materials, low cost, easy to
preserve, and suitable to make non-formaldehyde glue.
[0071] The technical solution to achieve the first objective of the
present invention is: A distiller's grain based reinforced material
used for wood-based panels with characteristics in that it is
composed of distiller's grain, inorganic material, and polymeric
water-resistant material by blending, curing, and milling to obtain
a powder. The weight percentage of each component described above
is as follows: 50 to 90% for distiller's grains, 10 to 35% for
inorganic material, 1.about.20% for water-resistant polymer
material and the sum of the weight percentage of each component is
100%; In which, the distiller's grain is one or more of dried whole
stillage of DDGS, distiller's dried crude DDG and distiller's dried
solubles DDS.
[0072] The said inorganic material is a calcium compound and/or
silicate, in which calcium compound and silicate with a weight
ratio of 1:0 to 4. The said polymer water resistant material is a
polyisocyanate, blocked polyisocyanates, and one or more epoxy
resins.
[0073] The preparation method of Distiller's grain-based reinforced
material for wood-based panels is: According to formulation weight
percentage, mix formulated amount of distiller's grains, inorganic
material, polymer water-resistant material to blend for 0.5-1 h,
seal the blend to allow to stand overnight for curing, using
conventional jet milling equipment for milling, collect powdery
material sized at the range of 80 to 600 mesh to be used as the
distiller's grain based reinforced material for wood-based panels
applications.
[0074] A distiller's grain based reinforced material for wood-based
panels with the characteristics in which the inorganic material of
the calcium compounds can be one or several of the compounds from
calcium carbonate, calcium sulfate, calcium chloride, calcium
oxide, calcium hydroxide, calcium phosphate, calcium magnesium
phosphate. The silicates are sodium silicate and/or potassium
silicate.
[0075] The second objective of the present invention is to provide
an environmentally friendly, low-cost, good water resistance, high
bonding strength distiller's grain based non-formaldehyde glue.
[0076] The technical solution to achieve the second objective is: A
distiller's grain based non-formaldehyde glue formulated from
distiller's grain based reinforced material for wood-based panels,
with the characteristics in which it is based on 20-50 wt % of
distiller's grain based reinforced material, 0.1-5 wt % of the
additives, the rest weight percentage amount of water as raw
materials. The glue is obtained by stirring and mixing. The
additives are one or more of a thickener, a defoaming agent, a
wet-strengthen agent and a curing agent.
[0077] The non-formaldehyde distiller's grain based adhesive, with
the characteristics in which the thickener additive is a inorganic
thickener, a cellulosic thickener, a natural polymer thickening
agent or it's derivative, and a synthetic polymer thickener; The
de-foaming additive is a silicone oil based, a polyether based, a
higher alcohol based, a mineral oil based and a vegetable oil
based; The said curing agent additive is one of an organic amine,
an organic acid anhydride, and a compound containing imidazole
group.
[0078] The technical effects of the present invention are: ( ) The
technology solutions to produce Distiller's grain-based reinforced
material for wood-based panels are mixing distiller's grain as the
main raw material with suitable amount of inorganic materials and
water-resistant polymer materials. Distiller's grain is the
by-products of the bioethanol production using crops such as corn,
barley, sorghum, sweet potatoes and so on by fermentation. For
example, three tons of corn can produce 1 tonne alcohol and 1 tonne
distiller's grain. The dried whole stillage corn DDGS contains 20
to 30% crude protein, 3 to 12% of crude fat and now is currently
limited to be used as a biological protein animal feed. In the
present invention, it is unexpected to discover that a distiller's
grain based reinforced material for making wood panels containing
distiller's grains with certain amount of biological protein, fat
and cellulose, combining with the suitable amount of inorganic
materials and water resistant polymer material can be obtained. The
material can be used to make non-formaldehyde glue to solve the
problem of the release of formaldehyde from wood panels.
[0079] The distiller's grain based non-formaldehyde glue derived
from the Distiller's grain-based reinforced material with suitable
inorganic materials and polymer waterproof material can have
suitable viscosity and water resistance. With the increased
shortage of oil resource, bioethanol derived from corn and wheat,
etc by fermentation has become an important way to solve the energy
crisis. Therefore, the production volume of the distiller's
byproducts will be gradually increased with very rich sources to
meet the needs of industrial production of glue. The distiller's
grain based reinforced material can be easy to store and the
Distiller's grain-based formaldehyde-free glue can be formulated
when it is needed for wood panel production.
[0080] {circle around (2)} Distiller's grain-based non-formaldehyde
glue in the present invention is easy to prepare. It can be used
with the existing process for the preparation of various types of
wood-based panels to give the bonding strength and water resistance
equal or superior to existing plywood made from phenolic and
urea-formaldehyde glue. The wood panel has no release of
formaldehyde from the glue and it is the real green products. It
also solves the problems of high cost of soybean and blood glue,
smells, easy to spoilage and poor water resistance.
SPECIFIC EMBODIMENTS
[0081] The following examples of the invention will be further
described in the embodiments, but not limited to such specific
embodiments.
[0082] All the raw materials used in the examples were commercially
available, unless it has noted industrial supplies, otherwise it
can be purchased through commercial channels.
Example 1B: Preparation of Distiller's Grain-Based Reinforced
Material for Wood Panels Sample 1.about.6
[0083] {circle around (1)} Formulation
[0084] The weight percentage of the components for present
invention to make distiller's grain-based reinforced material is as
follows: 50 to 90% distiller's grain, 10 to 35% inorganic material,
water-resistant polymer material 1-20%, the total weight
percentages of each component is 100%; inorganic material is a
calcium compound and/or silicate. The weight ratio of calcium
compound/silicate compound is 1:0 to 4. The specific formulations
are shown in Table 1B.
TABLE-US-00002 TABLE 1B 1 2 3 4 5 6 Weight of Weight of Weight of
Weight of Weight of Weight of component component component
component component component Component (kg) (kg) (kg) (kg) (kg)
(kg) Distiller's grain (62.5%) (62.5%) (64.5%) (64.5%) (66.7%)
(66.6%) {circle around (1)}DDG 100 / 50 / / / {circle around
(2)}DDS / 100 50 / / / {circle around (3)}DDGS / / / 100 100 100
In-organics (31.25%) (31.25%) (25.8%) (32.3%) (23.3%) (16.7%)
{circle around (1)}sodium 25 25 25 25 25 / silicate {circle around
(2)}Calcium 10 15 15 / / 25 Carbonate {circle around (3)}Calcium /
10 / / / / sulfate {circle around (4)}Calcium 15 / / 25 10 /
chloride Water- (6.25%) (6.25%) (9.7%) (3.2%) (10%) (16.7%)
resistant polymer {circle around (1)}PHDI / / / 5 / / {circle
around (2)}PMDI 10 / 15 / 15 25 {circle around (3)}Epoxy resin / 10
/ / / / Total 160 160 155 155 150 150 Note 1: Data in brackets is
the weight percentage for each component in the distiller's grain
based reinforced material. Note 2: dried whole stillage DDGS, dry
coarse distiller's grain DDG, distillers dried grains with solubles
DDS are prepared by fermentation of corn starch, by-product of
alcohol. Its quality conforms to GB/10647-2008 standard;
Polyisocyanate PHDI (grades XL600, the Perstorp products, Sweden),
polyisocyanates PMDI (grades 44V20, Bayer products); epoxy resin
(grade 5881A/B, Zhongshan chemical products); the rest are
commercially available industrial products.
[0085] {circle around (2)} Preparation
[0086] According to Table 1B, weigh out the formula amount of
distiller's grain, inorganic materials, polymer waterproof material
and transfer them into a 500 L conical mechanical mixing equipment
to mix for 0.5 h. After the mixing, the blend is sealed for aging
overnight and it is milled using conventional jet milling equipment
to collect 300 mesh powder to obtain distiller's grain-based
reinforced material sample 1-6 respectively.
Example 2B: Preparation of Formaldehyde-Free Distiller's Grain
Based Glue
[0087] The Distiller's grain-based formaldehyde-free glue in
present invention has the weight percentage of distiller's grain
based reinforced material at 20-50 wt %, the additive at 0.1-5 wt %
and the rest being water and it is produced by mixing. The additive
is one or several of thickener, de-foaming agent, wet strengthen
agent and curing agent.
[0088] {circle around (1)} Preparation of Distiller's Grain Based
Non-Formaldehyde Glue Sample 1A.about.6A
[0089] Weigh 35 kg of sample 1-6 produced according to Example 1B
respectively. To each sample, 64.9 kg of water was added and
stirred using a high shear mixer used in paint industry at the
speed of 300 revolutions/min. After stirring for 1 hour, add 0.1 kg
silicone based defoamers (grades FAG470, Union Carbide
Corporation), and mix at 100 rev/min for 1 hour to obtain the
Distiller's grain based glue without formaldehyde sample
1A.about.6A
[0090] {circle around (2)} Preparation of Distiller's Grain-Based
Formaldehyde-Free Glue 7A.about.8A
[0091] Weigh 35 kg of sample 2 and 6 prepared in Example 1B
respectively and to each sample, 59.9 kg of water was added and
stirred using a high shearing machine used the paint industry at
300 rpm/stirred for 1 hour. Then 4.9 kg of wet strengthen agent
polyamide epichlorohydrin resin (grades MS, Zibo Chemical Co., St.
Enoch product) and 0.1 kg silicone based defoamers (grades FAG470,
Union Carbide Corporation) were added and mixed at 100 rev/min for
1 hour to obtain Distiller's grain-based formaldehyde-free glue 7A
and 8A.
[0092] Test of Distiller's Grain-Based Formaldehyde-Free Adhesive
Properties
[0093] (a) Preparation of Plywood Samples for Testing
[0094] Seven layers of plywood was produced using distiller's grain
based non-formaldehyde glue 1A.about.8A from Example 2B.
[0095] {circle around (1)} Raw Materials
[0096] Veneer sheet size: horizontal sheet size 1230.times.930 mm,
vertical sheet size 930.times.615 mm: 100 kg of Distiller's
grain-based formaldehyde free glue 1A.about.8A;
[0097] {circle around (2)} The specific preparation method for
plywood is as follows:
[0098] The horizontal veneers and vertical veneers were passed
through a four roller coating machine to get double side coated
with glue. The glue coated veneers were cross-staggered and cold
pressed for 45 minutes. After repairing any defects of the
cold-pressed plywood, the staged 5-layer plywood was transferred to
a hot pressing machine to press for 10 minutes at the temperature
of 120.degree. C. and a pressure of 100 kg. After sanding, the
5-layer plywood was produced. Further coating glue on top and
bottom side of the 5-layer plywood and cover two sheets of wood
veneers on top and bottom of the 5-layer plywood for cold press.
After repairing any defects, the plywood was subjected to hot press
under the same conditions as described above to obtain 7-layers
plywood. The resulting 7-layer plywood was sawn into 8.0
cm.times.2.5 cm strips as specimens for testing.
[0099] (b) Determination of Dry Shear Strength of the Specimen
[0100] The specimens produced using the said distiller's grain
based non-formaldehyde glue 2A, 4A.about.8A were stored at room
temperature for a week. Then, the dry shear strength was tested
according to GB/T9846-2004 method. The 7-layer plywood produced
using conventional urea-formaldehyde and phenol-formaldehyde glue
was compared. Test results are shown in Table 2B.
[0101] (c) Determining the Shear Strength of Wet Specimens
[0102] 7-layer plywood specimen prepared using Distiller's grain
based non-formaldehyde glue 2A, 4A.about.8A were immersed in
boiling water for 4 h, then separately placed the flat specimen in
an air convection drying oven set at 63.+-.3.degree. C. for 20 h,
then immersed the specimen in boiling water for 4 h again. Removing
the specimen from the water and cooling at room temperature for 10
min. In accordance with GB/T9846-2004 method, the wet shear
strength of the specimen was tested. In comparison, 7-layer plywood
specimen produced using conventional urea-formaldehyde glue and
phenol-formaldehyde glue was tested. Test results are shown in
Table 2B.
TABLE-US-00003 TABLE 2B Dry shear Type of Glue Samples strength,
MPas Wet shear strength, MPas 2A 2.6 0.8 4A 2.0 1.5 5A 3.8 1.8 6A
4.5 1.6 7A 3.2 2.0 8A 4.0 2.8 Urea formaldehyde, solid 2.0
dismembered content 50 wt % Phenol-formaldehyde, 4.5 3.5 solid
content 50 wt % Note: The higher dry shear strength, the stronger
adhesive bonding; the higher the wet shear strength indicates the
better water resistance.
[0103] The test results in Table 2B show:
[0104] {circle around (1)} The dry shear strength of the plywood
produced using distiller's grain base formaldehyde-free glue of the
present invention is greater than the plywood produced using
urea-formaldehyde glue and dose or equivalent to the plywood
produced using phenol-formaldehyde glue, indicating distiller's
grain based formaldehyde-free glue has the equivalent degree of
adhesive strength to the existing formaldehyde glue. The wet shear
strength was significantly higher than urea-formaldehyde glue, and
close to the phenol formaldehyde glue, showing distiller's grain
based formaldehyde-free glue has good water resistance compared to
existing formaldehyde glue.
[0105] {circle around (2)} 2A and 7A were produced using the same
distiller's grain based reinforced material sample 2; 6A and 8A
were produced using the same distiller's grain based reinforced
material sample 6. In the preparation of 7A and 8A, the polyamide
epichlorohydrin wet strengthen resin were added, which resulting
higher wet shear strength and dry shear strength. This indicates
that polyamide epichlorohydrin wet strengthen agent can improve the
bonding strength of sample 7A and 8A, particularly the water
resistance has been significantly improved.
[0106] (D) Test the Water Resistance of Specimen
[0107] 1A-8A distiller's grain based formaldehyde-free glue
produced 7-layer plywood specimen were placed in water at room
temperature for 1 month; at 70.degree. C. and 100.degree. C. water
for two hours and 4 hours and then checked with the naked eye to
observe whether the sheet layers have opened up. In comparison,
7-layer plywood specimen produced using conventional
urea-formaldehyde glue and phenol-formaldehyde glue was tested.
Test results are shown in Table 3B.
TABLE-US-00004 TABLE 3B Water at Room 70 C. water 100 C. water Type
of glue used temperature 1 month 2 hours 4 hours 1A intact intact
Partially dismembered 2A intact intact Intact 3A intact Partially
Partially dismembered dismembered 4A intact intact Intact 5A intact
intact Intact 6A intact intact Intact 7A intact intact Intact 8A
intact intact Intact Urea- dismembered dismembered Dismembered
Formaldehyde Phenol- intact intact Intact formaldehyde
[0108] Test results as shown in Table 3B indicate that distiller's
grain based non-formaldehyde glue in present invention has better
water resistance than urea-formaldehyde glue, and has equivalent
result to phenol formaldehyde glue but achieving no formaldehyde
release from the glue.
[0109] The Distiller's grain-based formaldehyde-free glue can be
used to prepare medium density fiberboard by the conventional
method. The test result of its internal bond strength is 0.70
N/mm2, surface bonding strength is 0.8 N/mm2, the elastic modulus
is 4000 N/mm2, the thickness swelling (24 h) is less than 15%. It
can meet the requirements of national standard for medium density
fibreboard manufacturing.
[0110] The Distiller's grain-based formaldehyde-free glue can be
used to prepare chipboard by the conventional method. The test
result of its internal bond strength is 0.80 N/mm2, the elastic
modulus is 3500 N/mm2 and the thickness swelling (24 h) is less
than 15%. It can meet the requirements of national standard for
chipboard. The present invention utilizes corn and wheat based
distiller's grains from byproducts of bioethanol production to make
distiller's grain based reinforced material and then further
formulate the material into distiller's grain based
non-formaldehyde glue. In line with current environmental
requirements, the invention can achieve the objective of no release
of formaldehyde from the glue. It also solves the problems of high
cost, easy to spoilage and poor water resistance of biological
glue. The glue has reached and exceeded the adhesion properties and
water resistance of current urea-formaldehyde and phenol
formaldehyde. It can be used to prepare various types of wood-based
panels.
DESCRIPTION 3
Field of Invention
[0111] This invention concerns novel and versatile adhesive
products and glue derived from algal materials. In particular, the
processed algal adhesive materials have dry and wet strength
similar to those produced using formaldehyde and phenol based
processes that are the standard adhesives in industry. Algal based
adhesives have the potential to replace currently used formaldehyde
based wood adhesives, thus providing a `low carbon, low toxicity
and sustainable source of adhesives. Depending on the purity and
source of the algal material, the modified bio-adhesives can also
be used in more demanding `niche` applications such as biomedical,
marine, and automotive industrial applications. The invention
further relates to algal-derived glues and adhesive products
containing a crosslinked network which can be further processed
into powder form to become adhesive gel or aqueous glue which would
be amenable to many industrial manufacturing processes.
[0112] Background Art and Related Disclosure
[0113] The manufacture of adhesives is a global multi-$Billion
industry. The largest quantity of adhesive is used in the
construction industry for the production of millions of tonnes of
plywood, fibreboard and particleboard every year.
[0114] The huge volume of adhesives manufacture leads to two main
problems:
[0115] The limited stocks and the price of oil on which much
adhesive chemistry is based (formaldehyde and phenol)
[0116] The toxicity of the adhesive products due to their
containing formaldehyde and phenol Due to the inherently finite
nature of fossil fuel resources, the world faces the challenge of
finding suitable renewable substitutes that can begin to replace
petrochemicals both as a source of energy and as a source of
materials for plastics, rubbers, fertilizers, and fine
chemicals.
[0117] The other significant issue and cause of public concern is
the potential toxicity of current adhesives. Organic polymers of
either natural or synthetic origin are the major chemical
ingredients in all formulations of wood adhesives.
Urea-formaldehyde is the most commonly used adhesive, which can
release low concentrations of formaldehyde from bonded wood
products under certain service conditions. Formaldehyde is a toxic
gas that can react with proteins of the body to cause irritation
and, in some cases, inflammation of membranes of eyes, nose, and
throat. It is a suspected carcinogen, based on laboratory
experiments with rats and many people have identified it as a
potential factor in `sick building` syndrome.
[0118] Phenol-formaldehyde adhesives, which are used to manufacture
plywood, flakeboard, and fiberglass insulation, also contain
formaldehyde. However, formaldehyde is efficiently consumed in the
curing reaction, and the highly durable phenol-formaldehyde,
resorcinol-formaldehyde, and phenol-resorcinol-formaldehyde
polymers do not chemically break down in service to release toxic
gas. However, it uses the petroleum-based resource and also
expensive.
[0119] Increasing environmental concerns and strict regulations on
emissions of toxic chemicals have forced the wood composites
industry to develop environmentally friendly alternative adhesives
from abundant renewable substances such as soybean protein, animal,
casein, vegetable, and blood. Also, adhesives from lignin, tannin,
and carbohydrates have been studied for replacement of synthetic
adhesives that are the main adhesives used in the manufacture of
wood composite products.
[0120] However, these types of adhesives suffer from technical
disadvantages. These adhesives are generally used for
non-structural applications, due to their poor water resistance and
low strength properties. Modifications including further
purification to obtain high protein contents, increases of the
specific surface area of the materials, denaturation of the protein
by acid, alkaline and surfactants have been shown to be useful to
enhance the wood adhesive strength. However, these modifications
significantly increase the cost for manufacturing.
[0121] It would, therefore, be advantageous to provide adhesives
which are `low carbon and sustainable produced and which have low
toxicity but retain the strength of the current range of
formaldehyde or phenol based adhesives.
[0122] One of the possible alternatives to petroleum-based fuels
and products is biomass such as algae. Algae biomass contains
lipids, proteins, and carbohydrates that can be processed into
fuels or other valuable co-products through chemical, biochemical,
or thermochemical means. The lipids are of particular interest in
current research due to the ability to use the algal oils to
produce biodiesel. Algae stands out from other sources of biomass
with respect to lipid production with some estimates stating that
algae is capable of producing up to 30 times as much oil per unit
area of land as conventional oilseed crops under ideal conditions.
Additionally, algae has the added benefit of not competing with
traditional food crops because it can be grown on marginal lands
and can utilize brackish or waste water resources.
[0123] Other than investigating algal lipids and biodiesel
production, this invention has focused on the algal mass for use in
bio-adhesives in wood composite process and other applications. The
use of algae as a `feedstock` source for the production of
adhesives offers the advantages of `low carbon` processes,
sustainability and `greener` production processes.
[0124] It is, therefore, a primary objective of the present
invention is to provide a description of an algae-based adhesive
which is strong, versatile and inexpensive to manufacture.
[0125] It is, therefore, a further object of the present invention
to provide a stable aqueous adhesive comprising algal-material
derived from naturally occurring blue algae, brown algae
(Phaeophytes), red algae (Rhodophytes), that are safe and
water-resistant for wood application.
[0126] It is a further object of the present invention to prepare
algae based adhesive products that are produced by mixing dry algae
materials with additives and further milled into fine powder. This
acts to increase the adhesive strength and broaden their
suitability for adhesive applications. This also has the additional
advantage of generating a product that is easy to store for longer
shelf-life and transportation.
[0127] It is yet a further objective of the invention to prepare
algae based adhesive products that are produced by mixing dewatered
algae materials, e.g. algae blue (water content less than 70%) with
additives and homogenized into aqueous bio-adhesives.
[0128] It is yet a further object of the invention to prepare an
adhesive that consists essentially of byproducts of naturally
occurring algal after biofuel process.
[0129] It is yet a further object of the invention to prepare an
adhesive made from algae genetically engineered or modified to
enhance their growth rate or production efficiency.
[0130] It is yet another object of the invention to prepare
adhesive products that comprise naturally algal materials in dry
powder form (less than 500 .mu.m) that are blended with a
multifunctional crosslinking agent to form a crosslinked network to
enhance the water resistance of the adhesives.
[0131] It is further another object of the invention to mill the
powder to be less than 250 .mu.m for formulation into aqueous
adhesives.
[0132] It is yet another objective of the invention to prepare
adhesive products that comprise above aqueous adhesives and
optionally a wet-strengthen agent or/and a crosslinking agent for
water-resistant wood industry application and other niche
applications.
DETAILED DESCRIPTION OF THE INVENTION
[0133] The current invention concerns novel bio-adhesives derived
from algal materials.
[0134] According to a first aspect of the invention there is
provided algae based bio-adhesives consisting of algae mass,
crosslinking agents and inorganic fillers and optionally other
additives for making aqueous algal bio-adhesives.
[0135] According to a second aspect of the invention there is
provided a process for manufacturing such algal based
bio-adhesives, the process comprising the steps of: [0136] a.
Combining algal material obtained directly from green-blue algae,
red algae, brown algae or biodiesel byproducts of algae with
defined dryness and suitable protein content, a cross-linking
agent, and fillers to form a blend using a mechanical mixer or
blender,
[0137] Whereas in step a: the algal material has the water content
less than 70%; preferably less than 40%; most preferably less than
20%;
[0138] the crosslinking agent is selected from a organic polymeric
material with crosslinkable groups such as poly-isocyanate, epoxy
resin, or an inorganic material such as silicates, borates or
mixture of polymeric crosslinker and the inorganic substance;
[0139] the fillers are calcium materials such as calcium oxide,
calcium hydroxide, calcium chloride, calcium carbonate, calcium
sulfate, preferably calcium oxide, calcium sulfate which can
dewater during the blending process. The algal material in the
blend has the content between 50-89%, crosslinking agent has
1.0-20%, and fillers are 10-30%. [0140] b. Milling the blend via a
micronisation milling machine or any other chosen mechanical
milling machine to produce powdery material with particle size
between 30-500 .mu.m, preferably, between 30-250 .mu.m, most
preferably 30-125 .mu.m. [0141] c. Mixing the powdery material with
water, optionally with addition of a defoamer or an anti-foaming
agent, a thickener and optionally with a crosslinking agent or
wet-strength agent, wherein defoamer is selected from food grade
deformer used in milk, protein process industry, such as mineral
oil, vegetable oil or white oil based deforming agent; the
thickener selected are food grade water soluble natural polymer
such as cellulose derivatives e.g. HPMC, CMC, proteins such as
gelatin, alginate, chitosan; the wet strength agent is
polyamideamine-epichlorohydrin (PAE), the crosslinking agent is a
polymeric isocyanate with the isocyanate group blocked to obtain
algal aqueous bio-adhesives with solid content between 20-60%,
preferably 20-50%, most preferably 20-40%.
[0142] According to the invention there is provided a process for
manufacturing algae based bio-adhesives, the process comprising the
steps of: [0143] a. combining algal material, a cross-linking agent
and inorganic fillers to form a blend by mechanical blender; [0144]
b. Micronising the blend to obtain powdery material; and [0145] c.
Mixing the powdery material with water, optionally with the
addition of other additives such as defoaming agent, thickener, wet
strength agent and another crosslinking agent to form algal based
bio-adhesives.
[0146] In the present invention to make algal based bio-adhesives,
the algal materials can be obtained from Cladophora, which appears
to be one of the most abundant types of algae in streams, rivers,
and ponds around the world. They can be cultivated in open ponds
and closed photobioreactors. While open pond cultivation requires
less energy and has lower capital cost, photobioreactors have the
potential to produce larger quantities of algal biomass and
minimize contamination. In addition algae can be obtained from
unwanted natural incidents of excessive local growth. For example,
in China, there are bursts of large growth of blue algae every year
in the national river system and there are growths (`blooms`) of
red and brown algae along the seashore due to excessive fertilizer
use. The algae materials used from a variety of sources have been
harvested directly by float collection from water or sea or by
other common harvesting methods including sedimentation,
flocculation, centrifugation, filtration, and flotation with float
collection. Following harvesting, the algal biomass is typically
dried to increase shelf life. Many methods of drying can be used,
including spray-drying, drum-drying, and sun-drying. Typical water
content of the algae after harvesting is around 40-70%. Further
drying can obtain a dry mass with water content less than 40% and
typically less than 20% making it suitable for the current
invention.
[0147] Once the algae are dry, the cells must be disrupted to
release the lipids for biodiesel production. Cell disruption
methods vary according to the properties of the algal species used.
Some common methods of cell disruption are cell homogenizing, bead
milling, ultrasounds, autoclaving, freezing, organic solvents, and
enzyme reactions. The byproducts after removal of lipids can also
be used for current invention.
[0148] The important byproducts after removal of lipids are
proteins and carbohydrates. Some algae contain up to 60% protein. A
well-known alga that is currently cultivated for its protein
content is the cyanobacterium species Athrospira, better known as
Spirulina.
[0149] Spirulina is reported to contain not only around 60% raw
protein, but also vitamins, minerals and many biologically active
substances. Its cell wall consists of polysaccharides, has a
digestibility of 86 percent, and can be easily absorbed by the
human body. Spirulina can be easily cultivated in mass production
in china, India and USA. It is one of the sources of raw algae
materials used in the examples in the current invention.
[0150] Other algae species are known to have high protein content
can also be used as feed materials for the invention as shown in
Table 1C. Despite its high protein content, algae has not gained
significant importance as food or food substitute yet. Strict
approval regulations for new foodstuffs are a barrier, but also the
lack of texture and consistency of the dried biomass, its dark
green colour and its slight fishy smell are undesirable
characteristics for the food industry. However, this does not
affect the uses for this invention.
TABLE-US-00005 TABLE 1C General composition of % dry mass of
different algae materials (Becker, E. W. (2007). "Micro-algae as a
source of protein." Biotechnology Advances 25(2): 207-210) Alga
Protein Carbohydrates Lipids Anabaena cylindrical 43-56 25-30 4-7
Aphanizomenon flos-aquae 62 23 3 Chlamydomonas rheinhardii 48 17 21
Chlorella pyrenoidosa 57 26 2 Chlorella vulgaris 51-58 12-17 14-22
Dunaliella salina 57 32 6 Euglena gracilis 39-61 14-18 14-20
Porphyridium cruentum 28-39 40-57 9-14 Scenedesmus obliquus 50-56
10-17 12-14 Spirogyra sp. 6-20 33-64 11-21 Arthrospira maxima 60-71
13-16 6-7 Spirulina platensis 46-63 8-14 4-9 Synechococcus sp. 63
15 11
[0151] The crosslinking agent used in current invention is
polymeric isocyanate which is used to produce polyurethane. The
polyisocynate functional groups used in current invention include
PMDI, PHDI, Polyurethane pre-polymer, blocked polyisocynates such
as polyisocyanates with phenol, .epsilon.-caprolactam blocked. A
blocked polyisocyanate can be defined as an isocyanate reaction
product which is stable at room temperature but dissociates to
regenerate isocyanate functionality under the influence of heat
around 100-250.degree. C. Blocked polyisocyanates based on aromatic
polyisocyanates dissociate at lower temperatures than those based
on aliphatic ones. The dissociation temperatures of blocked
polyisocyanates based on commercially utilized blocking agents
decrease in this order:
alcohols>.epsilon.-caprolactam>phenols>methyl ethyl
ketoxime>active methylene compounds.
[0152] Other crosslinking agent can be used in current invention
include epoxy-resins. Epoxy resins, also known as polyepoxides are
a class of reactive prepolymers and polymers which contain epoxide
groups. Epoxy resins are polymeric or semi-polymeric materials and
An important criterion for epoxy resins is the epoxide content.
This is commonly expressed as the epoxide number, which is the
number of epoxide equivalents in 1 kg of resin (Eq./kg), or as the
equivalent weight, which is the weight in grams of resin containing
1 mole equivalent of epoxide (g/mol). One measure may be simply
converted to another:
Equivalent weight(g/mol)=1000/epoxide number(Eq./kg)
[0153] The epoxy resin can be used in current invention include
Bisphenol A epoxy resin, Bisphenol F epoxy resin, Aliphatic epoxy
resin and Glycidylamine epoxy resin.
[0154] The content of the polymeric crosslinking agent mixed with
algal materials is between 1.0-20%.
[0155] Other crosslinking agents can be used include inorganic
materials such as silicates and borates which can be used
separately or mixed with above polymeric crosslinking agent. The
total content is in the range of 1.0-20%, preferably in the range
of 1-10%, most preferably in the range of 5-10%.
[0156] The fillers used for current application are calcium based
inorganic materials. They can be used to dewater the algal
materials and adjust the reheological properties of the final
bio-adhesives. They can also be useful to help the subsequent
milling process. The more calcium materials are incorporated, the
more dry blend can be obtained. The typical content of the calcium
materials such as single calcium oxide, calcium chloride calcium
carbonate and calcium sulfate or their mixtures is in the range of
10-30%. The optimised composition for easy to mill can be adjusted
by changing the ratio of algal mass and the fillers.
[0157] After the blending with an industrial mechanical blender,
the mixture needs to be stored for overnight (>8 hrs) before
milling. The purposes of the subsequent milling process has two
aspects: one is to break the cell walls of the algal materials to
release the protein and the second is to have a homogenized mixture
in powder form to be able to form bio-adhesives for easy to spray
or spread for applications. The milling process can be performed by
readily available micronisation equipments, or mechanical milling
machines, including Jet Milling machine, ball milling machine,
mechanical grinding machine etc. The particle size obtained is
controlled at 30-500 .mu.m, preferably at 30-250 .mu.m, most
preferably at 30-125 .mu.m.
[0158] The algal bio-adhesives can be formulated by adding above
milled powder into premeasured water in a batch vessel with a mixer
or pumping into a mechanical static mixer with calculated amount of
water, or into a batch homogeniser or online homogeniser including
French Press, Manton-Gaulin homogeniser for continuous formulation
of the aqueous bio-adhesives.
[0159] The solid content of the formed bio-adhesives is between
20-50% and preferably between 20-40%.
[0160] Optionally, in the formulation of the aqueous bio-adhesives,
some additives can be added during manufacturing to obtain
optimized viscosity and enhanced wet strength for applications.
[0161] The additives include defoamer or an anti-foaming agent, a
thickener and optionally with a crosslinking agent or wet-strength
agent, wherein defoamer is selected from food grade deformer used
in milk, protein process industry, such as mineral oil, vegetable
oil or white oil based deforming agent; the thickener selected are
food grade water soluble natural polymer such as cellulose
derivatives e.g. HPMC, CMC, proteins such as gelatin, alginate,
chitosan etc; the wet strength agent is
polyamideamine-epichlorohydrin (PAE), the crosslinking agent is a
polymeric isocyanate with the isocyanate group blocked. The
percentage of each additive considered to be added is in the range
of 0.01-5%, preferably in the range of 0.1-5%, most preferably in
the range of 0.5-5%.
[0162] The main application of current invention of algal
bio-adhesives is in the field of production of wood based panels to
replace formaldehyde based wood adhesives. The wood based panels
include plywood, fibreboard and particle board.
[0163] The algal bio-adhesives can also be used for making
paper-based board such as paper packaging board, cardboard, carton
packaging material for recyclable food packaging, gift packaging
and medical packaging. Other applications include adhesives for
furniture used in hospital and school. The bio-adhesives can also
be used to make fibreboard based on non-wood materials such as
straw. The straw based fibreboard can be used as packaging
materials for food. The algal bio-adhesives can also be used in
marine board whereas the highly water-resistant wood board is
required. Although the invention has been described in connection
with specific preferred embodiments, it should be understood that
the invention as claimed should not be unduly limited to such
specific embodiments, various applications of the described modes
of carrying out the invention which are obvious to those skilled in
the art are intended to be covered by the present invention.
[0164] The invention now will be further exemplified.
Example 1C Preparation of Algal Bio-Adhesive
[0165] Cyanobacteria or blue-green algae was obtained from Tai Lake
blue-green algae treatment station in China. It was centrifuged to
obtain a dry mass with 40% water content and the particle size is
less than 500 .mu.m. In a mechanical blender (250 KG volume
capacity), 70 kg of the blue-green algae, 10 kg of calcium oxide
powder (200 meshes) and 10 kg of sodium silicate was added and
mixed for 30 mins. To the mixture, 2 kg of PMDI was slowly added
during mixing within 20 mins and blended for further 30 mins to
obtain a well mixed blend. The blend was sealed and stored
overnight for 10 hours, and then transferred to an Air-Jet milling
machine to obtain fine powder with particle size around 38 .mu.m.
In a 500 L high-shear mixing vessel for producing coating material,
100 L water was added, and then 50 kg of above milled powder was
added and mixed for 60 mins. 100 g of defoaming agent was added to
obtain the algal bio-adhesives ready for plywood process. The solid
content is about 33%.
[0166] Application of Algal Bio-Adhesives for Plywood:
[0167] 5 pieces of poplar veneers were cut into size at 36
cm.times.36 cm. The above algal bio-adhesive was brushed onto one
side of the first piece and one side of the last piece. Two sides
of the rest of 3 pieces. Amount of bio-adhesives on each veneer was
controlled with a balance. 5 pieces of poplar veneers were
cross-staged. Assembled wood specimens were pressed at 3 MPa and
120.degree. C. for 10 min with a hot press. The wood assemblies
were conditioned at 23.degree. C. and 50% RH for 48 h and then cut
into five pieces with overall dimensions of 80.times.20 mm and
glued dimensions of 20.times.20 mm.
[0168] The cut wood specimens were conditioned for 4 additional
days at the same conditions before testing. Shear strength testing
was performed using an Instron (Model 4465; Canton, Mass., USA) at
a crosshead speed of 1.6 mm/min according to ASTM Standard Method
D906-98(2011). Shear strength, including dry strength and wet
strength, were performed following ASTM Standard Methods (ASTM
D906-98 2011) at maximum load was recorded. Values reported are the
average of five specimen measurements.
[0169] Water resistance test: Specimen was boiled at 100.degree. C.
for 2 hours. The specimen is removed from water and visually
inspected for evidence of dismemberment.
[0170] Comparison of Urea-Formaldehyde (UF) glue and
Phenol-Formaldehyde (PF) glue to make plywood: Commercially UF and
PF for pressing plywood were carried out as the method shown in
Example 1C.
Example 2C: Preparation of Algal Bio-Adhesive
[0171] Cyanobacteria or blue-green algae was obtained from Tai Lake
blue-green algae treatment station in China. It was centrifuged to
obtain a dry mass with 40% water content. In a mechanical blender
(250 KG volume capacity), 70 kg of the blue-green algae, 10 kg of
calcium oxide powder (200 meshes) and 10 kg of sodium silicate was
added and mixed for 30 mins. To the mixture, 2 kg of PMDI was
slowly added during mixing within 20 mins and blended for further
30 mins to obtain a well mixed blend. The blend was sealed and
stored overnight for 10 hours, and then transferred to an Air-Jet
milling machine to obtain fine powder with particle size around 38
.mu.m. In a 500 L high-shear mixing vessel for producing coating
material, 150 L water was added, and then 50 kg of above milled
powder was added and mixed for 30 mins. To the mixture, 12.5 kg of
PAE and 2.5 kg of PMDI was added and mixed for 60 mins. 100 g of
defoaming agent was added to obtain the algal bio-adhesives ready
for plywood process. The solid content is about 30%.
[0172] The plywood using above algal bio-adhesive was produced
according to the same method as example 1C.
Example 3C: Preparation of Algal Bio-Adhesive
[0173] Cyanobacteria or blue-green algae was obtained from Tai Lake
blue-green algae treatment station in China. It was centrifuged to
obtain a dry mass with 40% water content. In a mechanical blender
(250 KG volume capacity), 70 kg of the blue-green algae, 10 kg of
calcium oxide powder (200 meshes) and 20 kg of sodium silicate was
added and mixed for 30 mins. To the mixture, 1 kg of PMDI was
slowly added during mixing within 20 mins and blended for further
30 mins to obtain a well mixed blend. The blend was sealed and
stored overnight for 10 hours, and then transferred to an Air-Jet
milling machine to obtain fine powder with particle size around 125
.mu.m. In a 500 L high-shear mixing vessel for producing coating
material, 100 L water was added, and then 50 kg of above milled
powder was added and mixed for 30 mins. To the mixture, 12.5 kg of
PAE and 2.5 kg of PMDI was added and mixed for 60 mins. 100 g of
defoaming agent was added to obtain the algal bio-adhesives ready
for plywood process. The solid content is about 35%.
[0174] The plywood using above algal bio-adhesive was produced
according to the same method as example 1C.
Example 4C: Preparation of Algal Bio-adhesives
[0175] Cyanobacteria or blue-green algae was obtained from Tai Lake
blue-green algae treatment station in China. It was centrifuged to
obtain a dry mass with 40% water content. In a mechanical blender
(250 KG volume capacity), 70 kg of the blue-green algae, 10 kg of
calcium oxide powder (200 meshes) and 20 kg of sodium silicate was
added and mixed for 30 mins. To the mixture, 1 kg of PMDI was
slowly added during mixing within 20 mins and blended for further
30 mins to obtain a well mixed blend. The blend was sealed and
stored overnight for 10 hours, and then transferred to an Air-Jet
milling machine to obtain fine powder with particle size around 38
.mu.m. In a 500 L high-shear mixing vessel for producing coating
material, 100 L water was added, and then 50 kg of above milled
powder was added and mixed for 30 mins. To the mixture, 5.0 kg of
waterborne blocked polyisocyanates (WB905) was added and mixed for
60 mins. 100 g of defoaming agent was added to obtain the algal
bio-adhesives ready for plywood process. The solid content is about
35%.
[0176] The plywood using above algal bio-adhesive was produced
according to the same method as example 1C.
Example 5C: Preparation of Algal Bio-Adhesive
[0177] Spirulina dry powder was obtained commercially and it
contains about 60% protein. 10 kg of the algae, 1 kg of calcium
oxide powder (200 meshes) and 1 kg of sodium silicate was added and
mixed for 30 mins. To the mixture, 1 kg of PMDI was slowly added
during mixing within 20 mins and blended for further 30 mins to
obtain a well mixed blend. The blend was sealed and stored
overnight for 10 hours, and then transferred to an Air-Jet milling
machine to obtain fine powder with particle size around 38 .mu.m.
In a 100 L high-shear mixing vessel for producing coating material,
40 L water was added, and then 10 kg of above milled powder was
added and mixed for 30 mins. To the mixture, 1.0 kg of waterborne
blocked polyisocyanates (WB905) was added and mixed for 60 mins.
100 g of defoaming agent was added to obtain the algal
bio-adhesives ready for plywood process. The solid content is about
20%.
[0178] The plywood using above algal bio-adhesive was produced
according to the same method as example 1C.
Example 6C: Application of Algal Bio-Adhesives for Preparation of
Particle Board
[0179] Algal bio-adhesive produced in example 2C was used to
prepare particle board. 150 g of algal bio-adhesive was added
slowly to 600 g of pine wood particles having a moisture content of
approximately 5% and mixed with a mechanical mixer. A
9-inch.times.9 inch.times.9 inch wood forming box was centered on a
12 inch.times.12 inch.times.0.1 inch stainless steel plate, which
was covered with aluminum foil. The wood-adhesive mixture is slowly
added into the forming box to achieve a uniform density of
particles coated with bio-adhesive. The mixture was compressed by
hand with a plywood board and the wood forming box was carefully
removed so that the particle board matte would not be disturbed.
Then, the plywood board was removed, a piece of aluminum foil was
placed on the matte, and another stainless steel plate was placed
on top of the matte. The particle board matte was then pressed to a
thickness of 3/4 inch using the following conditions: 120 psi for
10 minutes at a press platen temperature of 170 C. The particle
board was trimmed to 5 inches.times.5 inches to check the water
resistant property.
TABLE-US-00006 TABLE 2C Test results of plywood produced from algal
bio-adhesives in example 1C-6C Water resistance test Dry strength
Wet strength (boiling water for two Plywood (MPa) (MPa) hours)
Example 1C 1.8 0.8 Intact Example 2C 3.0 1.5 Intact Example 3C 2.5
1.0 Intact Example 4C 2.5 1.0 Intact Example 5C 3.5 1.6 Intact
Example 6C / / Intact Formaldehyde-Urea 2.5 / Dismembered resin
Phenol-Urea resin 3.4 1.8 intact
* * * * *