WO2012004725A1

WO2012004725A1 - Method for producing insulating material

Info

Publication number: WO2012004725A1
Application number: PCT/IB2011/052947
Authority: WO
Inventors: Andrea Cavaleri; Claudio Cerutti; Davide Contu
Original assignee: Nesocell S.R.L.
Priority date: 2010-07-07
Filing date: 2011-07-04
Publication date: 2012-01-12
Also published as: EP2591164A1; ITTO20100589A1; IT1400884B1

Abstract

A process for producing a cellulose-based thermally and/or acoustically insulating material, wherein said cellulose is at least in part derived from paper-mill sludge, characterized in that it envisages the addition to said sludge of at least one copper-based compound with biocidal action.

Description

"Method for producing insulating material"

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TEXT OF THE DESCRIPTION

The present invention relates to the production of thermal and acoustic insulators.

The invention specifically regards a process for producing a cellulose-based thermally and/or acoustically insulating material, of the type described in the international patent application No. WO2010067338 filed in the name of the present applicants .

Said type of process envisages producing a cellulose-based thermally and/or acoustically insulating material starting from paper-mill sludge constituting the waste from known industrial processes for the production of paper as raw material.

The use of the waste from the paper-mill industry mitigates the environmental impact of the product on the ecosystem. In the case in point, paper-mill sludge entails a high environmental impact so much so that the national standards envisage that treatment thereof as "special waste". In particular, paper-mill waste sludge is classified as "pollutant special waste" or "non- pollutant special waste" according to the chemical additives used in the production process. The costs deriving from disposal of this waste have a significant effect on the budgets of paper mills.

In order for it to be used as raw material for the production of flaked insulating material, the sludge must, however, be first sanified and protected from possible proliferation of micro-organisms.

The need to sanify the insulating material is even more accentuated in conventional production processes, where the insulating material in the form of flakes is obtained starting from cellulose-based dry material (e.g., pulping of newspapers, waste paper and cardboard, etc.). Currently known are sanification processes that envisage the addition of boron compounds (e.g., boric acid, borax, etc.) in the dry mixture, which have the purpose of performing a bioinhibiting action .

Following upon recent scientific studies acknowledged by various legislative bodies such as, for example, the European Community, boron-based compounds must be handled and used according to stringent criteria of environmental and health safety, which considerably complicate management thereof and limit their spread on the market.

For these reasons, the cellulose-based insulating materials produced via conventional processes using boron-based additives that up to now have witnessed a considerable interest, could encounter difficulties in extending their own diffusion as compared to insulating materials of a plastic or mineral type.

Summary of the invention

The object of the present invention is to provide cellulose-based thermally and/or acoustically insulating materials of an improved type.

According to the present invention, the above object is achieved thanks to the solution recalled specifically in the ensuing claims. The claims form an integral part of the technical teaching provided herein in relation to the invention.

In various embodiments, a process for producing a cellulose-based thermally and/or acoustically insulating material is provided, wherein added to the cellulose is at least one copper-based compound with biocidal action. The biocidal and preserving action of copper may be enhanced by additives, with or without flame-retardant action, which bestow on the insulating material a slight basicity.

The invention also regards a thermally and/or acoustically insulating material in the form of flakes. In various embodiments said insulating material comprises a copper-based compound with biocidal action possibly enhanced in its biocidal action by additives capable of rendering the end product slightly basic or neutral, thus inhibiting proliferation of an extensive category of micro-organisms and thus increasing the durability thereof. In various embodiments, amongst the additives used for this purpose substances already known in the literature for their high flame-retardant power are contemplated (e.g., aluminium trihydroxide, the family of ammonium phosphates, urea, etc.) or with reduced or zero antiflame power (e.g., calcium hydroxide, magnesium hydroxide, calcium carbonate, etc . ) .

Detailed description

The invention will now be described in detail, purely by way of non-limiting example, with reference to the annexed drawings, in which:

- Figure 1 represents a first embodiment of a process for the production of thermally and/or acoustically insulating material in cellulose flakes from waste from processes for the production of paper;

Figure 2 represents a second alternative embodiment of a process for the production of thermally and/or acoustically insulating material in cellulose flakes from waste from processes of production of paper; and

- Figure 3 represents an embodiment of a process for the production of cellulose flakes starting from pulping of newspapers, paper or cardboard, or from differentiated collection of paper.

In the ensuing description, numerous specific details are provided aimed at an in-depth understanding of the embodiments. The embodiments can be provided without just one or without many of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials, or operations are not shown or described in detail so that aspects of the embodiments will not be obscured.

Reference to "an embodiment" or "one embodiment" in the framework of the present description is meant to indicate that a particular configuration, structure, or characteristic described in relation to the embodiment is comprised in at least one embodiment. Hence, phrases such as "in an embodiment" or "in one embodiment" that may be present in different points in the context of the present description do not necessarily all refer to one the same embodiment. In addition, the particular configurations, structures, or characteristics may be combined in any adequate way in one or more embodiments .

The references used herein are merely provided for convenience and do not define the sphere of protection or the scope of the embodiments.

In various embodiments, paper-mill sludge, with high amounts of long-fibre, medium-fibre, and short- fibre cellulose are used in the production of bulk insulating material in flakes. The paper-mill sludge considered hereinafter can contain different amounts of water .

An innovative aspect of various embodiments is represented by the fact that a copper-based compound, possibly enhanced by other additives able to bestow basicity on the product, is added to the paper-mill sludge, in the pulping of newspapers, paper, or cardboard, from which the insulating material in cellulose flakes is obtained. Said addition can occur in any step of the production process. The flaked material obtained consists of an innovative material that has a high stability and resistance to external agents .

In various embodiments, said copper-based compound contains at least one from among copper (II) sulfate, copper (I) sulfate, copper (II) oxide, copper (I) oxide, tetracopper oxychloride, copper calcium oxychloride, and copper hydroxide.

In various embodiments, said copper-based compound, preferably copper (II) sulfate, is combined in a neutral mixture with substances able to bestow basicity on the product, such as, for example, calcium hydroxide, magnesium hydroxide or a mixture of the two. In various embodiments, said neutral or basic mixture of copper (II) sulfate and calcium and/or magnesium hydroxide is present in an amount ranging from 0.01 wt% to 10 wt% with respect to the cellulose-based end product. In various embodiments, said mixture contains copper (II) sulfate in an amount ranging from 2 wt% to 40 wt% and calcium and/or magnesium hydroxide in an amount ranging from 60 wt% to 98 wt%.

The copper-based compound, as likewise the basic or neutral mixture mentioned above, can present either in the form of powdered material or in the form of liquid material. Possible drying or moistening steps can be envisaged to facilitate the bond between the cellulose-based material and said substances. In any case, the insulating material obtained from the process described herein must be impregnated or else even only partially coated with said substances.

The mixture referred to above may be enhanced in its action of preservative of durability through the use of substances with high antiflame power, use of which as flame retardants is already known in the literature (for example, aluminium trihydroxide, sodium bicarbonate, urea or ammonium phosphates, etc.)_/ which are moreover able to bestow basicity on the cellulose insulating product. In various embodiments, the copper, with or without the substances with low or zero antiflame power such as calcium and/or magnesium hydroxide, is present in ratios of 1 part of copper compound to an amount ranging from 2 to 50 parts per weight of the aforementioned substances with high antiflame power.

Described hereinafter are three examples of processes of production of said insulating material.

Example 1 - Process for the production of bulk insulating materials in flakes

A scheme of an industrial process for the production of the aforesaid bulk insulating materials in flakes is illustrated in Figure 1.

The industrial process A envisages that the paper mills 1 produce particular types of paper 2 using medium-fibre and long-fibre cellulose. The paper-mill sludge 3, which is the residue of the industrial process A, is re-used in an industrial process B for the production of thermally and/or acoustically insulating material in flakes.

In the context of the process B for the production of insulating material in flakes, the sludge 3 can be used as a substitute for, or in combination with, conventionally used raw materials. Known industrial processes for the production of flaked insulating material conventionally use first-extraction cellulose 11 and/or recycled cellulose 12 (paper for pulping) . The industrial process B hence initially subjects the substitute secondary raw materials 3 (sludge) that characterize the present invention, optionally together with the conventional raw materials 11 and/or 12, to a reduction in size through supply to a shredding device 4. Next, a possible series of mixers 5 is used for homogeneizing materials of various origin. The sludge 3, possibly in association with first-extraction cellulose 11 and/or recycled cellulose 12, is then fed to a pulper 6. The sludge is then introduced into a mill 8 possibly associated to a drier device 9. The mill 8 may contain metal beaters (such as, for example, balls or rollers) or other hammering devices (such as, for example, a disk mill or a hammermill) , in order to open up the cellulose fibres, thus reducing their density and producing flakes. The cellulose flakes 10 obtained at the end of the process may be used for thermal and/or acoustic insulation.

In various embodiments, there is envisaged addition, in the paper-mill sludge, of a copper-based compound with biocidal action. Said addition is performed in paper mills when the sludge is still flowable, with a content of material in the solid state of between 1 wt% and 10 wt%. Alternatively, addition of the copper-based compound may be envisaged during processing in the pulper 6.

In various embodiments, said copper-based compound contains a neutral mixture of copper (II) sulfate and calcium and/or magnesium hydroxide. In various embodiments, said neutral mixture of copper (II) sulfate and calcium hydroxide is present in an amount ranging from 0.01 wt% to 10 wt% with respect to the end product. In various embodiments, said mixture contains copper (II) sulfate in an amount ranging from 2 wt% to 40 wt% and calcium and/or magnesium hydroxide in an amount ranging from 60 wt% to 98 wt%.

In various embodiments, moreover added to the paper-mill sludge is a compound with a base of aluminium hydroxide with antiflame action. In various embodiments, aluminium hydroxide is present in an amount ranging from 5 wt% to 35 wt% with respect to the end product. Said addition is performed in paper mills when the sludge is still flowable, with a content of material in the solid state ranging from 1 wt% to 10 wt%. Alternatively, the addition of the copper-based compound can be performed during processing in the pulper 6.

Example 2 - Process for the production of bulk insulating materials in flakes

A scheme of an industrial process for the production of the aforesaid bulk insulating materials in flakes is illustrated in Figure 2.

The industrial process A envisages the production of special types of paper 16 using virgin cellulose 11 or recycled cellulose 12. After storage 13 the cellulose reaches the refinement station 14 where on one side there arrive the waste materials deriving from the successive passages of the process, whereas on the other side there the paper-mill waste is eliminated, which is stored in step 17 and thickened in step 19.

Said waste is designed to be used for the production of flaked insulating material in the process B described hereinafter.

In various embodiments, when said waste is still in the paper mill, it is treated with additives 18 in liquid solution and/or suspension of powders in water. Said additives can be one or more from among flame retardants, dyes, biocides, etc.

In various embodiments, among said additives 18 a compound with a base of aluminium hydroxide with antiflame action is envisaged. In one embodiment, the aluminium hydroxide is present in an amount ranging from 5 wt% to 35 wt% with respect to the end product.

In various embodiments, in combination with the additives 18 there is moreover envisaged a copper-based compound with biocidal action 15.

In various embodiments, said copper-based compound contains a neutral or basic mixture of copper (II) sulfate and calcium and/or magnesium hydroxide. In various embodiments, said neutral or basic mixture of copper (II) sulfate and calcium and/or magnesium hydroxide is present in an amount ranging from 0.01 wt% to 10 wt% with respect to the end product. In various embodiments, said mixture contains copper (II) sulfate in an amount ranging from 2 wt% to 40 wt% and calcium and/or magnesium hydroxide in an amount ranging from 60 wt% to 98 wt%.

It is preferable for the additives indicated above to be added when the paper-mill waste or sludge is still flowable, with a content ranging from 1 wt% to 10 wt% of material in the solid state.

The waste form the process A is hence dehydrated subsequently in step 19, for example mechanically using an auger, and finally possibly treated once again with additives 15 such as flame retardants, biocides, dyes, etc., for example of the type indicated above. In this further step, the additives may present either in the liquid form (solution or dispersion) or in the solid form (powder) .

The waste thus produced can be transferred and used as raw material of the process B for the production of thermally and/or acoustically insulating material in flakes. Said waste is substantially constituted by sludge, comprising a content ranging from 25 wt% to 60 wt% of material in the solid state.

The process of production B illustrated in Figure 2 constitutes an embodiment alternative to the one illustrated in Figure 1. Said process envisages that initially stored in a step 21 are the waste from the process A and possibly compounds in a mixture that can envisage also first-extraction cellulose 11 and/or recycled cellulose 12.

During storage, they can be treated with additives 18 in liquid solution (liquid phase) such as flame retardants and other additives 15 such as dyes, biocides, etc., for example, of the type referred to above .

Hence, the material is dehydrated in a step 22, either naturally or using systems of forced ventilation and/or heating, and then sent on to the hammering step 23. In said step, carried out for example using a hammermill, the dehydrated material expands in volume until it forms insulating flakes.

It is moreover possible to treat the flakes with additives in powder form 15, for example of the type referred to above, either in the hammering step 23 or in the subsequent pre-bagging storage step 24. Example 3 - Process for the production of bulk insulating materials in flakes from pulp or from waste of newspapers, paper, or cardboard

A scheme of an industrial process for the production of the aforesaid bulk insulating materials in flakes is illustrated in Figure 3.

The paper or the waste cardboard or pulp 12 enters the production process and undergoes deferrization 26, passes through the machinery 27, 29 and 31, which performs a mechanical action on the paper in the first place to reduce the size thereof and then to obtain the insulating product. The mechanical process can envisage intermediate aeration stations 28 and 30. The product is then mixed in 33 with flame retardants 18 and powdered biocides possibly with the addition of binders such as, for example, starch.

In various embodiments, amongst the additives 18 a compound with a base of aluminium hydroxide with antiflame action is envisaged. In one embodiment, aluminium hydroxide is present in an amount ranging from 5 wt% to 35 wt% with respect to the end product.

Of course, the details of construction and the embodiments may vary widely with respect to what has been described and illustrated herein without thereby departing from the sphere of protection of the present invention, as defined by the annexed claims.

Claims

1. A process for producing a cellulose-based thermally and/or acoustically insulating material, characterized in that it envisages the use of at least one copper-based compound as biocide, which is added to the cellulose-based material that forms said insulating material .

2. The process according to Claim 1, wherein said copper-based compound contains at least one from among copper (II) sulfate, copper (I) sulfate, copper (II) oxide, copper (I) oxide, tetracopper oxychloride, copper calcium oxychloride, and copper hydroxide.

3. The process according to Claim 1, wherein calcium and/or magnesium hydroxide are/is combined with said copper-based compound in a basic or neutral mixture that is added to said cellulose-based material.

4. The process according to Claim 3, wherein said neutral or basic mixture is present in an amount ranging from 0.01 wt% to 10 wt% with respect to the insulating material to be produced.

5. The process according to any one of Claims 3 and 4, wherein said mixture contains copper (II) sulfate in an amount ranging from 2 wt% to 40 wt% and calcium hydroxide in an amount ranging from 60 wt% to 98 wt%.

6. The process according to any one of Claims 1 to

5, wherein said insulating material is produced in the form of flakes.

7. A thermally and/or acoustically insulating material, which is cellulose-based and in the form of flakes, said material comprising a copper-based compound with biocidal action.

8. The insulating material according to Claim 7, wherein said copper-based compound contains at least one from among copper (II) sulfate, copper (I) sulfate, copper (II) oxide, copper (I) oxide, tetracopper oxychloride, copper calcium oxychloride, and copper hydroxide .

9. The insulating material according to Claim 7, wherein calcium and/or magnesium hydroxide are combined with said copper-based compound in a neutral or basic mixture .

10. The insulating material according to Claim 9, wherein said neutral or basic mixture is present in an amount ranging from 0.01 wt% to 10 wt%.

11. The insulating material according to any one of Claims 9 and 10, wherein said mixture contains copper (II) sulfate in an amount ranging from 2 wt% to 40 wt% and calcium hydroxide in an amount ranging from 60 wt% to 98 wt%.

12. The insulating material according to any one of Claims 9 to 11, wherein contained in said neutral or basic mixture is at least one from among aluminium hydroxide, sodium bicarbonate, urea, and ammonium phosphates as flame retardant.