Patent Application
20130005209
All patent and non-patent references cited in the present application are also hereby incorporated by reference in their entirety.
The present invention relates to a non-woven fibre product comprising recycled material and manufactured by a dry forming process, a method of manufacturing such product and the use of such recycled materials.
From U.S. Pat. No. 5,516,580 an insulation batt is known, where the material contains a portion of cellulose fibres, and longer bonding synthetic fibres. These synthetic fibres are so-called bi-component fibres that have an outer sheath which is heat-fused with outer sheaths of other synthetic fibres at crossing contact points thereof to form a matrix having pockets for retaining loose fill cellulose fibres therein. This matrix eliminates the need of an adhesive binder to retain the cellulose fibres in the matrix.
The drawback of this insulation board is that the fibre batt obtained hereby is not particularly resilient and the use of longer bi-component synthetic bonding fibres makes the product very expensive to manufacture.
A method of making a resilient mat is known from U.S. Pat. No. 5,554,238. The insulation mat according to this method comprises cellulosic and thermoplastic fibres. A mat is formed in an air-laying process and subsequently the surface is flame-treated to melt the thermoplastic component on the surface forming a skin which keeps the cellulosic fibres intact. The thermoplastic fibres in the interior of the mat remains unmelted, whereby the mat is provided with a spring-back characteristic, which allows the mat to retain most of its original shape after it has been compressed, e.g. for shipping.
However, this resilient mat has a “crisp” exterior surface reducing the resiliency of the mat as a whole and not homogeneously bonded throughout the product, which does not allow for easy handling since the product may easily delaminate or otherwise break up. The insulation effect is moreover reduced due to the more compact structure of the fibre product.
From WO 01/48330 a recyclable insulating mat comprising shredded waste paper or cardboard mixed with natural fibres and 5-50% polyester is known.
In DE 196 02 551 C1, there is described a mat for manufacturing self-supporting form parts by heat treatment. The mat comprises long natural fibres and thermoplastic binding means provided as synthetic fibres. The thermoplastic binding means are provided synthetic material with a high melting point and a low melting point.
It is an object of the present invention to provide a resilient fibrous product which is recyclable and inexpensive to manufacture from waste material.
This object is achieved by a non-woven fibre product comprising recycled material and manufactured by a dry forming process, said product comprising a first portion of up to 99% dust material, where the dust material is preferably recovered dust from manufacturing or the like of fibrous textile material, preferably cotton textiles, and a second portion at least 1% bi-component fibres having a length between 2-75 mm, preferably 2-25 mm in length.
Dust material from processing textile materials, from e.g. manufacturing, cutting, tumble drying and recycling of textiles, a waste product is dust which is frequently removed from filter screens and the like in the processing equipment. This dust is at present disposed of and shipped off to landfill or burned off. A textile processing business thus is faced with costs for removing and disposing of this dust material. However, according to the invention, the use of dust material is advantageous because there is now provided a product in which this waste material can be recycled and used for a useful purpose. The non-woven product obtained by the invention has excellent spring-back properties and is very inexpensive in manufacturing since the key ingredient, i.e. the dust material, is inexpensive in purchase. The dust material from textile processing are characteristic in that the textile fibres are very short and crimped since the fibres derive from yarns that are spun and subsequently woven and thereby provided with a spring-like, crimpy shape. By the invention it is thus realised that an airy, non-woven product is obtainable which has a very low density and with good insulation properties. The fibre mat products may accordingly be used for heat or sound insulation purposes, such as insulation in the housing sector, the automotive sector or for maritime purposes as well as within product types such as air condition equipment, machinery, wind turbines etc.. Accordingly, it is realised that the products may be provided in predetermined shapes to fit within or around panels or the like.
It is realised that by a dry-laid, air-laid or otherwise fibre formed product according to the invention a cost-effective fibrous, soft product of recycled materials can be provided in a predetermined shape which can be used in the packaging industry as a substitute for foam products or the like which are otherwise used for protecting goods, such as electronic products, etc. inside the package.
According to a second aspect of the invention, there is provided a method of manufacturing a non-woven product by dry forming a product of fibrous material, said method comprising the steps of:
By the invention, it is realised that the textile dust material can be recycled in an advantageous manner by utilising this material in an air-laid fibre mat which is obtainable by using the manufacturing technology disclosed in WO2005/044529. However it is realised that other dry-laying web forming processes may be used. Accordingly, an aspect of the invention involves the use of recyclable dust material for such an air-laid product as mentioned above by performing the method described above.
The fibre mat product according to the invention is furthermore advantageous since the product is resilient with spring-back properties, i.e. that the mat raises again after compression and resumes its original shape.
This advantageous characteristic of the product according to the invention is also enhanced by the use of bi-component fibres so that the resulting fibrous mat is very flexible as the bi-component fibres acting as binding means in the product are short. The bi-co fibres become hard when cured after having been heated above the melt temperature, so by using short bi-co fibres the bi-co fibres do not adversely affect the resulting product with respect to flexibility and elastic properties when cured due to their short length.
Moreover, it is realised by the invention that the bi-component fibres mix better with the recycled dust material fibres because of the short and/or crimped nature of the fibres whereby only a small proportion of bi-co fibres are needed to provide sufficient coherence of the product. This further enhances the flexibility of the fibrous product.
In a preferable embodiment of the invention there is provided a third portion of shredded textile material, such as recycled fibres from textile materials of so-called shoddy obtained by shredding the recycled textile material into fibres.
According to a preferred embodiment, at least 50% of the portion of bi-component fibres is crimped fibres with a length between 2 to 50 mm. By using short and crimped fibres, e.g. of a helical shape extra flexibility and resilience is achieved in the product allowing the product to appear softer and having good properties with respect to raising again after compression and resuming its original shape. It is also realised that the bonding fibres may be bi-component fibres substituted or supplemented with polyester fibres, polypropylene and/or other plastic fibres having bonding characteristics.
At least the first portion of fibrous material may preferably be provided with an additive. Accordingly, at least the third portion of shredded textile fibres may be impregnated with a material for wetting the third portion of fibrous material. Moreover, at least the first portion of fibrous dust material may be impregnated with a material for wetting the dust material. By impregnating the fibres prior to the heating, the resulting effect is found surprisingly advantageous. The fibres become crispy during the heating which in turn means that the resulting fibre mat product becomes easy to cut into a predetermined shape afterwards.
In an embodiment, the fibres are provided with fire-retarding chemical, such as Borax, Boric acid, Ammonium sulphate or aluminium sulphate and/or citrus based compounds, mixed with, sprayed onto or impregnated into the fibres either before, during or after the forming process, e.g. in the forming box before being laid on the forming wire. In another embodiment, the dry-formed fibre mat may be sprayed with fire-retarding chemical, e.g. after the mat is formed and heated.
In an advantageous embodiment, the fibre portion of dust material and/or the third portion of shredded textile fibres, such as shoddy, are impregnated before being advanced into the forming box. The impregnating material is preferably a fire-retarding chemical in liquid or powder form. Hereby, the individual fibres are saturated utilising that the nature of the fibres is that they are absorbent. This provides an efficient fire-retarding characteristic of the finished product since the fire retarding chemicals are absorbed in the fibres. The fire-retarding chemical may be in liquid or powder form.
It is found that the dry-laid fibre product can be produced with a grammar weight between 8 kg/m3 and 200 kg/m3, in particular between 8 kg/m3 to 20 kg/m3.
If extra bonding of the fibres is required, an additional fluidized binder may be sprayed into the forming box and onto the fibres therein. The fluidized binder may alternatively be sprayed onto the fibres. As a further alternative or as a supplement, binder in pulverised form may be mixed with the fibres before the mixture is forwarded to the forming box.
The invention is further explained with reference to the accompanying drawings which show diagrams of three embodiment of the manufacturing process for producing a product according to the invention.
With reference to the drawings, three examples of the invention are shown and described in the following:
A first portion of dust material recovered dust from manufacturing or the like of fibrous textile material, preferably cotton textiles, is provided. This dust material is a waste product in most textile processing operations and contains typically very short cotton fibres.
These fibre portions are mixed with a small second portion of bi-component fibres. These bi-component fibres comprise a core and an outer sheathing, said outer sheathing having a first melting temperature which is lower than the second melting temperature of the core. The purpose these bi-component fibres serve is to provide bonding between the fibres in the first portion of fibres. The bi-component fibres become hard when cured after having been heated above the melt temperature, so by using short bi-co fibres the bi-co fibres do not adversely affect the resulting product with respect to flexibility and elastic properties when cured due to their short length. Moreover, the short bi-component fibres blend very well with the fibres of the first portion ensuring a more homogeneous bonding throughout the product.
A third portion of waste material in the form of a shoddy, i.e. shredded textile material, predominantly comprising cotton fibres may also be provided as a portion for the air-laid product to be manufactured. This so-called shoddy material originates from fabric, such as garment, shredded into yarns of about 10-125 mm fibres. The shredded textile fibres will naturally contain an amount of dust material. This amount may be increased by providing a pre-treatment of the shredded textile fibres, such as a further shredding prior to the fibre mixture.
The mixture of fibres are forwarded to a forming box, preferably of the kind described in WO2005/044529, where the box is provided with a revolving belt screen allowing for an even distribution of fibres irrespective of their size.
The fibres are introduced into the forming box and laid on the forming wire beneath the forming box. The web of fibres is forwarded in a continuous motion through a heating station where the bi-component fibres are activated and the fibrous web is provided with its coherence.
During the heating process, the fibre mat is subjected to a heat of approximately 130° C. for a predetermined amount of time, such as 5 sec. to 5 min, whereby the bi-co fibres are activated.
The web is then cured as the heated bi-component fibres are cooled and the web may be forwarded through a pressing station for providing the resulting mat product with a predetermined density. Hereby, a cost effective fibre product having a grammar weight of 8-200 kg/m3 is provided, which has a good spring elastic effect and insulation properties.
The fibrous web may be sprayed with a fire-retarding substance, such as Borax, Boric acid, Ammonium sulphate or aluminium sulphate, for providing the product with fire-retarding properties. Alternative to spraying the formed web, this substance could also be sprayed into the forming box and thereby priming the fibres before the fibres are laid onto the forming wire.
In order to achieve a superior fire-retarding characteristic of the air-laid product, it is realised by the first portion of dust material may be treated with the fire-retarding chemical or other types of additives prior to the fibre mixing, cf.
It is furthermore realised that a portion of fruit or grain shells, such as rice shells or the like, can be added to the fibre mixture. This results in an airy product with robust properties.
By the present invention, it is realised that the variations of the above-mentioned example may be performed without departing from the scope of the invention as defined in the accompanying claims. For instance a portion of cellulose fibres or other types of fibres may be provided depending on which properties of the fibre product is required.
| Number | Date | Country | Kind |
|---|---|---|---|
| PA 2009 70203 | Nov 2009 | DK | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/DK2010/050305 | 11/12/2010 | WO | 00 | 8/28/2012 |
