GB2524462A

GB2524462A - Algal Bio-adhesives: Compositions, Process for Manufacturing, Formulations and Uses

Info

Publication number: GB2524462A
Application number: GB1400267.9A
Authority: GB
Inventors: Xiaobin Zhao
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-01-08
Filing date: 2014-01-08
Publication date: 2015-09-30
Also published as: GB201400267D0

Abstract

Algal bio-adhesives consisting of algae biomass, crosslinking agents, and fillers, and optionally with other additives to form aqueous bio-adhesives as substitutes of formaldehyde based glue for wood panel process are disclosed. The algal bio-adhesives can also be used for other purposes such as biomedical, marine, and automotive industrial applications. There is also provided a process for preparing such algal bio-adhesives which comprising the steps of: a) combining algal material, a cross-linking agent and inorganic fillers to form a blend by mechanical blender; b) micronising the blend to obtain powdery material and 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 algae based bio-adhesives.

Description

Aiqal Bio-adhesives: Compositions, Process for Manufacturing, Formulations and Uses Xiaobin Zhao

FIELD OF INVENTION

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 cross-linked 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. a

BACKGROUND ART AND RELATED DISCLOSURE

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 parlicleboard every year.

The huge volume of adhesives manufacture leads to two main problems: 1. The limited stocks and the price of oil on which much adhesive chemistry is based (formaldehyde and phenol) 2. The toxicity ol 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.

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.

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 phenol4ormaldehyde, 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.

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.

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.

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.

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.

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.

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.

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 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.

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.

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.

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.

It is yet another object of the invention to prepare adhesive products that comprise naturally algal materials in dry powder form (less than 500pm) that are blended with a multifunctional crosslinking agent to form a crosslinked network to enhance the water resistance of the adhesives.

It is further another object of the invention to mill the powder to be less than 250 pm for formulation into aqueous adhesives.

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

The current invention concerns novel bio-adhesives derived from algal materials.

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.

According to a second aspect ol the invention there is provided a process br manufacturing such algal based bio-adhesives, the process comprising the steps of: 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, Whereas in step a: the algal material has the water content less than 70%; preferably less than 40%; most preferably less than 20%; 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; 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%.

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-SOOpm., preferably, between 30-250 pm, most preferably 30-125 pm.

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 poyamideamine-epichlorohydrin (PAE), the crossUnking agent is a polymeric isocyanate with the isocyanate group bbcked to obtain aiga aqueous bio- adhesives with solid content between 20-60%, preferabUy 20-50%, most preferably 20-40%.

According to the invention there is provided a process for manufacturing algae based bio-adhesives, the process comprising the steps of: a. combining algal material, a cross-linking agent and inorganic fillers to form a blend by mechanical blender; b. Micronising the blend to obtain powdery material and 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.

In the present invention to make algal based bio-adhesives, the algal materials can be obtained from Gladophora, 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.

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.

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.

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.

Other algae species are known to have high protein content can also be used as feed materials for the invention as shown in Table 1. 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 1 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) 4Iui 4 2' 30 tWnvvdmwasththñbdü 4$ fl YikM;' pn'io' 2 2 12 IT 14-22 Dun thdk 32 p 14-. is: 2$-edini uhhqLth U) j'7 12-14 11-21 Spndm 1 4&o 8-14 4M

II

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, a-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°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> c -caprolactam>phenols>methyl ethyl ketoxime>active methylene compounds.

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) 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.

The content of the polymeric crosslinking agent mixed with algal materials is between 1.0-20%.

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%.

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.

After the blending with an industrial mechanical blender, the mixture needs to be stored for overnight (>8hrs) 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 pm, preferably at 30-250 pm, most preferably at 30-125 pm.

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.

The solid content of the formed bio-adhesives is between 20-50% and preferably between 20-40%.

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.

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 poyarriideamine-epichlorohydrin (RAE), the crosslinking agent is a polymeric isocyanate with the isocyanate group blocked. The percentage or each additive considered to be added is in the range ol 0.01-5%, preferably in the range of 0.1-5%, most preferably in the range of 0.5-5%.

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.

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-adheisives 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.

The invention now will be further exemplified.

Example 1 Preparation of Algal bio-adhesive: 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 pm. In a mechanical blender (250KG volume capacity), 70kg of the blue-green algae, 10kg of calcium oxide powder (200meshes) and 10kg of sodium silicate was added and mixed for 3omins. To the mixture, 2kg of F'MDI was slowly added during mixing within 2Omins and blended for further 3omins to obtain a well mixed blend. The blend was sealed and stored overnight for 1 Ohours, and then transferred to an Air-Jet milling machine to obtain fine powder with particle size around 38 pm. In a 500L high-shear mixing vessel for producing coating material, 100L water was added, and then 50kg of above milled powder was added and mixed for 6omins. bOg of defoaming agent was added to obtain the algal bio-adhesives ready for plywood process. The solid content is about 33%.

Application of algal bio-adhesives for plywood: pieces of poplar veneers were cut into size at 36cm X 36cm. 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 l2OC for 10 mm with a hot press. The wood assemblies were conditioned at 23C and 50% RH for 48 h and then cut into five pieces with overall dimensions of 80 x 20 mm and glued dimensions of 20 x 20 mm.

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, MA, USA) at a crosshead speed of 1.6mm/mm according to ASIM 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.

Water resistance test: Specimen was boiled at 100°C for 2hours. The specimen is removed from water and visually inspected for evidence of dismemberment.

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 Algal Bio-adhesive 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 (250KG volume capacity), 70kg of the blue-green algae, 10kg of calcium oxide powder (200meshes) and 10kg of sodium silicate was added and mixed for 3omins. To the mixture, 2kg of PMDI was slowly added during mixing within 2omins and blended for further SOmins to obtain a well mixed blend. The blend was sealed and stored overnight for lOhours, and then transferred to an Air-Jet milling machine to obtain fine powder with particle size around 38 pm. In a 500L high-shear mixing vessel for producing coating material, 150L water was added, and then 50kg of above milled powder was added and mixed for SOmins. To the mixture, 12.5kg of PAE and 2.5kg of PMIJI was added and mixed for 6omins. lOOg 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 algal bio-adhesive was produced according to the same

method as example 1.

Example 3 Preparation of Algal Bio-adhesive 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 (250KG volume capacity), 70kg of the blue-green algae, 10kg of calcium oxide powder (200meshes) and 20kg of sodium silicate was added and mixed for 3Omins. To the mixture, 1kg of PMDI was slowly added during mixing within 2omins and blended for further 3omins to obtain a well mixed blend. The blend was sealed and stored overnight for lOhours, and then transferred to an Air-Jet milling machine to obtain fine powder with particle size around 125 pm. In a 500L high-shear mixing vessel for producing coating material, 100L water was added, and then 50kg of above milled powder was added and mixed for Somins. To the mixture, 12.5kg of PAE and 2.5kg of PMDI was added and mixed for 6omins. bOg 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 algal bio-adhesive was produced according to the same

method as example 1.

Example 4 Preparation of Algal Bio-adhesives 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 (250KG volume capacity), 70kg of the blue-green algae, 10kg of calcium oxide powder (200meshes) and 20kg of sodium silicate was added and mixed for 3omins. To the mixture, 1kg of PMDI was slowly added during mixing within 2omins and blended for further Somins to obtain a well mixed blend. The blend was sealed and stored overnight for lOhours, and then transferred to an Air-Jet milling machine to obtain fine powder with particle size around 38 pm. In a 500L high-shear mixing vessel for producing coating material, 100L water was added, and then 50kg of above milled powder was added and mixed for 3omins. To the mixture, 5.0kg of waterborne blocked polyisocyanates (WB905) was added and mixed for GOmins. bOg 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 algal bio-adhesive was produced according to the same

method as example 1.

Example 5 Preparation of Algal Bio-Adhesive Spirulina dry powder was obtained commercially and it contains about 60% protein.

10kg of the algae, 1kg of calcium oxide powder (200meshes) and 1kg of sodium silicate was added and mixed for 3omins. To the mixture, 1kg of PMDI was slowly added during mixing within 2Omins and blended for further Somins to obtain a well mixed blend. The blend was sealed and stored overnight for lohours, and then transferred to an Air-Jet milling machine to obtain fine powder with particle size around 38 pm. In a 1 00L high-shear mixing vessel for producing coating material, 40L water was added, and then 10kg of above milled powder was added and mixed for 3omins. To the mixture, 1.0kg of waterborne blocked polyisocyanates (WB905) was added and mixed for 60mins. bOg of defoaming agent was added to obtain the algal bio-adhesives ready for plywood process. The solid content is about 20%.

The plywood using above algal bio-adhesive was produced according to the same

method as example 1.

Example 6 Application of algal bio-adhesives for preparation of particle board Algal bio-adhesive produced in example 2 was used to prepare particle board. 150g of algal bio-adhesive was added slowly to 600g of pine wood particles having a moisture content of approximately 5% and mixed with a mechanical mixer. A 9-inch x 9inch x 9 inch wood forming box was centered on a 12 inch x 12 inch x 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 ol 3⁄4 inch using the following conditions: l2Opsi for lOminutes at a press platen temperature of 170°C. The particle board was trimmed to 5inches X 5 inches to check the water resistant property.

Table 2 Test results of plywood produced from algal bio-adhesives in example 1-6 Plywood Dry strength (MPa) Wet strength (MPa) Water resistance test (boiling water for two hours) Example 1 1.8 0.8 Intact Example 2 3.0 1.5 Intact Example3 2.5 1.0 Intact Example 4 2.5 1.0 Intact Example 5 3.5 1.6 Intact

Example 6 / / Intact

Formaldehyde-Urea 2.5 / Dismembered resin Phenol -Urea resin 3.4 1.8 intact

Claims

Claims: 1. Algal bio-adhesives consisting of algae mass, crosslinking agents and inorganic fillers.
2. Algal bio-adhesives consisting of algae mass, crosslinking agents, inorganic fillers and also containing other optional additives e.g. defoamers, thickeners for making aqueous algal bio-adhesives.
3. Algal bio-adhesives consisting of algae mass, crosslinking agents, inorganic fillers and also containing other optional additives e.g. wet strength agent and another crosslinking agent for making niche' or specialist algal bio-adhesives.
4. The algal bio-adhesives in claim 1-3, wherein the algal sources are blue-green algae, red algae, and brown algae, which can be harvested from river and ocean.
5. The algal bio-adhesives in claim 1-3, wherein the algal sources are algae cultivated in a pond or photobioreactor.
6. The algal bio-adhesives in claim 1-3, wherein the algal sources are genetically modified or enhanced or selected algae cultivated in a pond or photobioreactor.
7. The algal bio-adhesives in claim 1-3, wherein the algal mass has the water content less than 70%, preferably less than 40%, most preferably less than 20%.
8. The algal bio-adhesives in claim 1, wherein the algal mass is from the biodiesel process byproducts of algae.
9. The algal bio-adhesives in claim 1-3, wherein the crosslinking agents are synthetic polymeric crosslinking agents and in-organic materials or mixture of them. The synthetic polymeric crosslinking agents are one of the polyisocyanates, polyisocyanates with blocked isocyanate groups and epoxy resins. The inorganic materials are silicates and borates.
10.The algal bio-adhesives in claim 1-3, wherein the fillers are calcium minerals including calcium oxide, calcium sulfate, calcium carbonate and calcium hydroxide.
11.The algal bio-adhesives in claim 2-3, wherein the additives include defoaming agent, wet strength agent, thickeners and crosslinking agent.
12.A process to prepare algal bio-adhesives in claim 1-3 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 micronisation milling machine or any other chosen mechanical milling machine to produce powdery material with particle size between 30-500 pm, preferably, between 30-250 pm, most preferably 30-125 pm.c. Mixing the powdery material with water, optionally with addition of other additives.
13. As claimed in claim 12 in step a, wherein the blend consists 50-89% of the algal material, 1.0-20% of crosslinking agent and 10-30% of fillers.
14.According to claim 12 in step c, the percentage of the each additive to form aqueous bio-adhesives is between 0-5%, preferably 0.1-5%.
15. As claimed in claim 12, wherein the defoamer is food grade defoaming agent, such as mineral oil, vegetable oil or white oil based deforming agent.
16.As claimed in claim 12 in step c, wherein, the thickener is water soluble natural polymer such as cellulose derivatives, proteins, alginate and chitosan.
17.As claimed in claim 12 in step c, wherein, the wet strength agent is polyamideamine-epichiorohydrin (PAE).
18.As claimed in daim 12 in step c, wherein the crosslinking agent is a polymeric isocyanate with the isocyanate group blocked.laAs claimed in claim 12 in step c, the algal aqueous bio-adhesives have the solid content between 20-60%, preferably 20-50%, most preferably 20-40%.20.Algal bio-adhesives as claimed in claim 1-3 for use in wood panel process as substitute of formaldehyde based wood adhesives.21.Algal bio-adhesives as claimed in claim 1-3 for use in water-resistant glue for paper packaging industry.22.Algal bio-adhesives as claimed in claim 1-3 for use in biomedical, healthcare, hospital, school building board decoration, assembling and construction.