AU666295B2

AU666295B2 - Method and apparatus for producing insulation materials

Info

Publication number: AU666295B2
Application number: AU89559/91A
Authority: AU
Inventors: Aaltje Elisabeth Maude; Derek Worthington Maude
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-11-12
Filing date: 1991-11-11
Publication date: 1996-02-08
Anticipated expiration: 2011-11-11
Also published as: AU8955991A

Description

MFTΉQD AND APPARATUS FOR PRODUCING INSULATION MATERIALS

This invention relates to a method and apparatus for the manufacture of insulation materials and to an insulation material made by the process and relates particularly but not exclusively to insulation materials and methods and apparatus for their manufacture manufactured from a combination of shredded and defibrillated fibrous cellulosic materials preferably in the form of a batt.

The thermal insulation and sound attenuation properties of cellulosic materials are well known and it is known that such materials may be used in insulation materials. Advantages of using such materials in insulation materials are that waste materials such as, newspaper, can be removed from the waste stream and recycled to form a useful product. Disadvantages of using cellulosic materials on insulation materials are that the materials must be treated to make them fire retardant and preferably insect, vermin and decay resistant. It is known to treat cellulosic materials such as wastepaper with fire retardant compounds such as, borax. Such compounds are hygroscopic and cellulosic materials treated with such compounds are non-resilient and subject to degradation.

A need exists for the effective utilization of waste materials. Paper waste and other fibrous cellulosic materials have been recognised as potential resource materials for various products including insulation materials due to their inherent insulating properties. Until now there has been a lack of economical methods to convert such waste to acceptable and viable materials which are environmentally friendly, low in production energy consumption and resistant to hazards or degradation which would reduce their life expectancy and, therefore, their usefulness.

Cellulosic fibres from paper waste or other cellulosic materials have been used previously as insulation but in a very limited way. Production has been restricted to loose fill products requiring special application methods and devices. Such material is highly vulnerable to moisture in its untreated state and could be subjected to long term degradation problems.

Mineral fibre insulation materials are brittle by nature and tend to degrade and break down if subjected to mechanical stresses releasing fine mineral particles into the environment which pose an unknown health risk. There is therefore a need to replace mineral fibre insulation materials with insulation materials which are less likely to be hazardous to health.

Various proposals have been put forward to utilize waste cellulosic materials to produce insulating materials. British patent 1359996 discloses an insulation material comprising a sandwich of shredded paper between two outer facing sheets of paper suitably treated with fire retardant materials such as ammonium dihydrogen phosphate and ammonium sulphate. At least one of the facing sheets is perforated. The outer facing sheets may be bonded to the shredded paper by spraying the shredded paper with a suitable bonding agent or adhesive prior to covering with the facing sheets. Pressure may be applied to the sandwich configuration to assist with the bonding of the shredded paper to the outer facing sheets. The material is specifically identified as an insulation material primarily designed as an acoustic insulation material with some thermal insulation properties. The product may be stored in rolls or cut into insulation batts of convenient size.

Australian patent Nos. 527843 and 540132 disclose a method of forming a batt . of bonded synthetic and wool fibres in which the mixture of fibres is ragged, teased or otherwise deferred to form a sliver of randomly dispersed fibres. The sliver is then passed through a lapping machine to form a mat of desired thickness. The mat is then sprayed with a mixture of fireproofing resins, smoke retardants and pesticides cured and if desired cut into batts of appropriate configuration.

The present invention seeks to overcome problems with prior art batts or insulation materials and to provide a safe and effective insulation material and to provide methods and apparatus for producing such batts or insulation materials. The present invention also seeks to provide a method of manufacture of a fibrous cellulosic insulating material which by varying the density of the cellulosic material can be manufactured in varying degrees of rigidity and fire, weather and rot resistant. It is an object of the invention also to provide a fibrous cellulosic insulating material having the above properties. The present invention, therefore, provides in one form a method of manufacturing an open fibrous cellulosic insulating material which comprises providing a shredded fibrous cellulosic material, coating said shredded material with a rigid or non- rigid binder to form a coated shredded material, introducing a defibrillated cellulosic material on and into said coated shredded material to provide a filled shredded material and compressing and curing said filled shredded material to cause said binder to bind the material to form said fibrous cellulosic insulating material.

Preferably the binder comprises a thermosetting resinous material which additionally contains fungicidal, insecticidal and/or fire retardant chemicals. Preferably the binder is applied to the shredded material by means of spraying. Preferably additional binder is applied to the filled shredded material prior to compression and curing. Preferably the shredded material is carded or combed prior to the application of the binder to provide a loose evenly formed bed of material to allow ease of introduction of the defibrillated material. Preferably the binder includes a cross linked thermosetting flexible polymeric material with elastic memory to provide the fibrous cellulosic insulating material with properties of resiliency and flexibility.

Suitable polymeric materials for inclusion in the binder are polymers, copolymers, modified polymers, acrylics, modified acrylics, P.V.A.'s, urea formaldehyde resin, phenol formaldehyde, resorcinoi formaldehyde, melamine formaldehyde and urethanes. The polymeric materials may be employed with thickeners, as is known in the art such as cellulosic thickeners (carboxy methyl cellulose, hydroxy ethyl cellulose, hydroxy methyl cellulose including any combinations thereof) caseins, flour and cornflour. The fire retardant chemicals may be chosen from any of the known fire retardant chemicals and preferably are selected from highly hydrated inorganic chemicals such as borax, hydrated alumina and the like.

Examples of fire retardant materials which may be used alone or in combination are calcium carbonate, calcium sulphate, calcium silicate, aluminium trihydrate, boric acid, borax, ammonium phosphates, poly ammonium phosphates, aluminium potassium sulphate, magnesium chloride, magnesium phosphate, sodium silicate, potassium silicate, metaborates, chlorinated acrylics; and chlorinated wax.

It will be appreciated by those skilled in the field that not all polymeric materials are compatible with fire retardant materials as suggested and that appropriate trials may be necessary to determine the compatibility or otherwise of polymeric material/fire retardant combinations. For example, it is known that sodium and potassium silicates and acidic polymers and acrylics; poly ammonium phosphate and alkaline polymers; and cellulosic thickeners and acidic fire retardant chemicals are not compatible. In addition to the above, consideration must be given to effective insecticide and brocide as it is well known that cellulose fibre and most fire retardants contain nutrients. These nutrients become accessible to micro organisms. Cellulose fibre is also subject to attack by insects and rodents. Thus whenever high humidity conditions prevail or when the cellulose fibre becomes otherwise wet, without a suitable biocide the cellulose fibre insulation material would soon grow mould and commence to degrade. A suitable biocide, insecticide or rodenticide of low toxicity and safe to the consumer and the environment is preferably incoφorated into the formula. The biocide and the insecticide must be compatible with the binder formula. The following are examples of acceptable biocides: Busan 1009 (T ), Busan TCMTB (^TM) , Kathon (^T ), Densil (™), Kocide (™) and insecticides: Peregin, Permethrin, Biosmethrin, Boron compounds, Busan 11 mi (™) Busan 1im2 (TM) ₀r combinations thereof.

Preferred fungicidal, insecticidal and bactericidal material is Thiocyanomethy! benzathiazoie, Kathon, Densil, Metaborates, Pyrethroids, Borax and other Boron compounds. The fungicidal and bactericidal chemicals should of course be substantially stable at the temperature of curing of the process which is of the order of 150°C depending on the particular binder material used.

The above binders must also be compatible with and/or preferably synergistic with the dry fire retardant incorporated during the manufacture of the defibrillated cellulosic material. The dry fire retardant is necessary as in grinding or milling paper or other cellulosic material the resulting dust can create an explosive mixture with air therefore it is a safety requirement to incorporate a fire retardant during the manufacture of the defibrillated cellulosic material. The dry fire retardant may be selected from the following materials for example:-

Ammonium phosphates, polyammonium phosphates, barium metaborate, chlorinated wax, aluminium trihydrate, borax, boric acid, calcium carbonate, magnesium chloride, magnesium phosphate, barium metaborate, barium sulphide, barium phosphate, antimony oxychioride, antimony trioxide, calcium sulphate, calcium silicate, sodium silicate, potassium silicate, aluminium potassium sulphate, or any combination of the above.

Particularly preferred fire retardants are:- Ammonium phosphates, aluminium trihydrate, ammonium phosphate, chlorinated wax, borax, barium metaborate, polyammonium phosphate and magnesium chloride.

The material prior to compression and curing is preferably evenly distributed by way of spiked combing rollers and combs between scrim material and passed to the compression step for compression to about 50% of its original height whilst curing. The compressed material may be cut into batts for roof or wall insulation or blanket, or into strips for wrapping around air conditioning ducts for example. The batts may be formed having a thickness of 100 mm for example. The batts so prepared have equivalent or better thermal insulation properties to fibre glass batts of similar thickness, have better tear strength and do not have the environmental and safety problems of fibre glass batts. The strips may be formed with thicknesses of between 25mm to 100mm of varying densities to provide the required thermal resistance for any particular purpose for example 25mm strips with corresponding or better thermal insulation properties to fibre glass the flexibility and resilience of the material permits the strips to be wound around. in a preferred embodiment the shredded fibrous cellulosic material is shredded waste paper. Other cellulosic or cellulose-like materials which can be used are shredded straw from wheat, rice, etc., shredded wood shavings.

In a preferred embodiment the defibrillated cellulosic material is defibrillated paper or cardboard waste which has been treated in, e.g. a hammer mill to reduce the material to a finely divided fluffy material. Similarly other cellulosic or cellulose-like materials as are indicated above may be utilized to form the defibrillated material. For example other cellulosic or cellulose-like materials which could be utilized are waste natural fibre materials or textile materials. There is no necessity for any de-inking or similar treatment of the waste cellulosic materials prior to incorporation into a product or prior to performing the method of the invention.

In a particularly preferred form of the invention the product contains shredded and defibrillated cellulosic material in a weight ratio of approximately 20:80. Binder is preferably added to the material in the range of from 5 to 25 parts by weight (most preferably from 10 to 20 parts by weight) of the combined cellulosic materials.

The present invention also provides in one form, apparatus for manufacturing an insulation material which comprises apparatus for the manufacture of sandwich cellulosic insulation material which includes means to form a mat of evenly distributed shredded cellulosic material, means to introduce defibrillated cellulosic material into the shredded cellulosic material, means to provide a cover sheet of cellulosic material to each face of the mat, means to introduce a bonding material to the shredded cellulosic material and to the cover sheets to permit the shredded cellulosic materials and the cover sheets to be bonded together to form a bonded insulation material. Preferably the shredded cellulosic material is provided from a shredder. Preferably the means for forming the evenly distributed shredded cellulosic material includes a conveyor means which spreads and distributes the shredded material to form an evenly distributed mat of shredded material. Preferably the conveyor means comprises a plurality of chain means which diverge from the shredder and which include spike means to spread and disperse the shredded material. Preferably the apparatus additionally includes air injection means to assist in distributing the defibrillated material through the shredded material. Preferably the apparatus includes curing means to cure the bonded insulation material.

A preferred form of apparatus and method in accordance with the invention will now be described with reference to the accompanying drawings, in which:

Fig. 1 represents a schematic elevational view of apparatus according to the invention;

Fig. 2 represents a plan view of spreader means of the apparatus;

Fig. 3 represents an end sectional view of comminuted material introduction means of the apparatus; and

Fig. 4 shows a schematic representation of a preferred process of the present invention.

Referring to Figs. 1 to 3 of the drawings, there is shown apparatus 10 comprising top sheet supply 20 and bottom sheet supply 21, shredder 11, spreader 12, conveyor 13, defibrillated material feed 14, air injectors 15, bonding material sprays

16, 17 and 18 and curing tunnel 19. Wastepaper is supplied to shredder 11 via conveyor 22. Shredded semi-compressed paper 23 which exits from the shredder 11 is spread and teased on spreader 12 and fed into conveyor 13.

A rotating drum (not shown) disposed above the chain bed spreader 12 with thin spring steel tynes may be used to further distribute the shredded material more evenly over the chain bed.

As the shredded material leaves the chain bed a double row of air holes (not shown) beneath the end of the chain bed may be included to blow low pressure air to help lift the formed shredded cellulosic material mat off the chain bed and into conveyor 13 to help it to maintain its shape as it passes through the conveyor for subsequent treatment.

The rotating drum disposed over the chain bed may be any diameter eg. from 50mm to 1000mm, the preferred diameter is 150mm. The spring steel tynes may be between 50mm and 200mm long with a preferred length of 110mm. There may be 20 tynes or 200 tynes with a preferred number of 90 tines evenly disposed around the surface of the drum.

The spread and teased shredded material 24 is sprayed with bonding material supplied via spray 16. The sprayed shredded material passes defibrillated material feed

14 ("DM feed") where defibrillated (e.g. finely divided fluffy comminuted wastepaper or cardboard) material is fed into the shredded material from the DM feed. Immediately following the DM feed the shredded material is subject to blasts or jets of compressed air from air injectors 15 to disperse the defibrillated material substantially evenly through the shredded material!

Bottom sheet 25 is sprayed on the inside thereof with bonding material supplied via spray 17 and similarly top sheet 26 is sprayed on the inside thereof with bonding material supplied via spray 18. The top and bottom sheets are brought into contact with the shredded material and compressed between hot plates 17 and cured in curing tunnel

19. The sandwich material may then be cut into batts or strip material as required.

The spreader 12 comprises a series of chains 28 which spread out from the exit of the shredder 11 to the width of the conveyor 13. As the chains 28 spread apart they are interspersed with additional chains 29, 30 to maintain adequate support for the spread teased shredded material. Each of the chains is provided with spikes 34 which are, for example between 75mm and 140mm high or could be all the same height. The preferred height is 110mm.

Each link of the chains could be fitted with this spike or only one in every 20 links. The preferred number is one in every five links.

As the shredded paper is forced out onto these spiked chains, the spiked chains become further apart as the chain moves away from the shredder, this teased and spreads the shredded paper to the full width of the spreader.

The shredded, sprayed material then passes past the two DM feeders 14 where cellulose fluff is injected into the sprayed shredded material. The fluff is pre-ground or milled and blown, via blowers into the troughs 29. These troughs have a series of dado blades 30 set at angles of approx. 60 degrees in each direction about axis 31 , left of centre, sloping to the left and to the right of centre, sloping to the right (as shown in Fig. 2). The DM feeder may additionally include baffles 33 to direct the defibrillated material, blown into the feeder by means not shown, towards the dado blades 31.

The dado blades turning on a shaft located in the centre of the trough, distribute the fluff evenly along its length and assist to force the fluff through the bottom 32 of the trough. The fluff is extruded in an even density mass. As this mass is extruded it is passed close to shredded paper and is blown into and around this shredded paper, by a series of air slugs, fired via a number of high pressure air injectors 15 (approx. 175), located each side of the shredded material. These nozzles fire the air slugs at different intervals and pressures to obtain maximum penetration and density of the fluff in the shredded material. The air slug may be of between V₁₀₀ of a second to one second duration, but preferably between ¹ o of a second and ₂ of a second duration.

The air slugs are controlled via a series of solenoid valves, which are designed to cover the full width and depth of the mat of shredded filled material. this mat now passes through two vibrating plates 32 to further enhance the distribution of the fluff through the shredded material.

The shredded material is preferably shredded newspaper or shredded stationary or computer paper but may be any suitable cellulosic material. The defibrillated material is preferably cardboard or other waste cellulosic material which has been ground or milled to form a finely divided defibrillated fluffy material. The defibrillated material may be made from waste cellulosic materials such as, bagasse, straw, rice hulls, peanut shells, coconut husks and the like.

The apparatus of the invention thus produces a sandwich of shredded filled cellulosic material between two sheet materials bonded by a suitable bonding material which is flexible, resilient and able to be cut into insulation batts of appropriate size or into strips of flexible insulation material for lagging pipes, ducts and the like. The sheet materials may be any suitable sheet material such as paper, plastics film, aluminium film or the like. It is possible to omit the upper sheet material provided that the upper surface of the shredded filled cellulosic material treated with binder is dried sufficiently prior to the compression of the batt to the desired thickness before the binder sets.

Referring to Fig. 4 there is shown a schematic representation of a preferred process according to the invention.

Shredded waste paper is conveyed from storage 41 and carded or combed at station 43 to ensure even distribution of the shredded waste. Binder from storage 44 is added to the shredded waste at station 45 and then conveyed to station 46 where defibrillated paper waste is added from storage 42. Further binder is added at station 48 and the material conveyed between scrim to compression station 49, curing station 50 and is eventually cut to required batt or strip size at cutting station 51. The following are examples of preferred binder formulations for use in the process of the invention.

Example 5

Chlorinated wax/acrylic polymer 25

Ammonium phosphate 30

Busan 1.1 m2 2

Busan 1009 1

Cellulosic thickener 2 Water to 100 Example 6

Chlorinated wax/acrylic polymer 25

Polyammonium phosphate 30

Kathon 0.5

Borax 2

Cellulosic thickener 2 Water to 100 Example 7

Modified acrylic (Joncryl 142LP) - 25

Aluminium trihydrate 28

QR 708 (thickener) 2

Busan 11 τ.2 2

Densil 0.5 Water to 100 Example 8

Modified acrylic (Duramol 695) 25

Ammonium phosphate 25

QR 708 (thickener) 1

Glycol 1

Busan 1009 1

Chlorinated wax 6

Busan 11 mz 1 Water to 100

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1 . A method of manufacturing an open fibrous cellulosic insulating material which comprises providing a shredded fibrous cellulosic material, coating said shredded material with a rigid or non-rigid binder to form a coated shredded material, introducing a defibrillated cellulosic material on and into said coated shredded material to provide a filled shredded material and compressing and curing said filled shredded material to cause said binder to bind the material to form said fibrous cellulosic insulating material.

2. A method as claimed in claim 1 in which the shredded material is carded or combed prior to the application of the binder to provide a loose evenly formed bed of material to allow ease of introduction of the defibrillated material.

3. A method as claimed in claim 1 or 2 in which further binder is applied to the filled shredded material prior to compression and curing.

4. A method as claimed in claim 3 in which the filled shredded material is carded or combed prior to application of the further binder material to distribute the defibrillated material within the shredded material and to facilitate penetration of the additional binder into the filled shredded material.

5. A method as claimed in claim 1 in which the binder includes a thermosetting plastics material.

6. A method as claimed in claim 5 in which the binder additionally includes one or more fire retardant and or biocidal materials.

7. A method as claimed in claim 6 in which the biocidal materials are selected from fungicidal, bacteriocidal, insecticidal and/or rodenticidal materials.

8. A method as claimed in claim 1 in which the binder is applied as a coating to the shredded cellulosic material by means of a spray or sprays.

9. A method as claimed in claim 3 in which the further binder is applied to the filled shredded material by means of a spray or sprays.

1 0. A method as claimed in claim 1 in which the fibrous cellulosic insulating material is cut into strips or batts.

1 1 . A method as claimed in claim 5 in which the thermosetting plastics material is a flexible thermosetting plastics material.

1 2. Apparatus for the manufacture of a cellulosic insulation material which includes means to form a mat of evenly distributed shredded cellulosic material, means to introduce defibrillated cellulosic material into the shredded cellulosic material, means to provide a cover sheet of cellulosic material to each face of the mat, means to introduce a binder to the shredded cellulosic material and to the cover sheets to permit the shredded cellulosic materials and the cover sheets to be bonded together to form a bonded insulation material.

1 3. Apparatus as claimed in claim 12 which includes a shredder to provide the shredded cellulosic material.

1 4. Apparatus as claimed in claim 12 in which the mat of evenly distributed cellulosic material is formed by means of a bed of chain conveyor means which diverge from the shredder to spread and evenly disperse the shredded cellulosic material.

1 5. Apparatus as claimed in claim 14 in which the chain conveyor means include upwardly directed spikes to spread and evenly dispense the shredded cellulosic material.

1 6. Apparatus as claimed in claim 15 in which the conveyor means serves also to transport the shredded cellulosic material.

1 7. Apparatus as claimed in claim 12 which includes one or more sprays to introduce the binder to the shredded cellulosic material.

1 8. Apparatus as claimed in claim 12 in which the means to introduce defibrillated cellulosic material includes means to evenly distribute the defibrillated cellulosic material across the width of the shredded material and compressed air means to force the defibrillated cellulosic material into and on the shredded cellulosic material.

19. Apparatus as claimed in claim 12 which additionally includes means to cure the bonded insulation material.

20. Apparatus as claimed in claim 12 which includes means to transport and constrain the shredded cellulosic material from the conveyor means to the curing means.

21. An open fibrous cellulosic insulation material which comprises shredded fibrous cellulosic material having defibrillated cellulosic material disposed therein and thereon and a binder to bind the insulation material in the form of a web, strip, roll, blanket or batt.

22. An insulation material as claimed in claim 21 in which the binder includes a flexible thermosetting plastics material.

23. An insulation material as claimed in claim 21 in which the binder additionally includes one or more fire retardant and/or brocidal materials such as fungicidal, bacteriocidal, insecticidal and/or rodenticidai materials.

24. An insulation material as claimed in claim 21 in which the binder additionally contains a filler or fillers.

25. An insulation material as claimed in claim 21 which includes a cover sheet of fire retardant treated paper on either side of the web, strip, roll, blanket or batt.

26. An insulation material as claimed in claim 21 in which the defibrillated cellulosic material is a fire retardant treated defibrillated cellulosic material.