DE2722774A1 - Thermoplastic fibre carpet waste recovery - effected by shredding waste into pieces, laying in layers, heating above m.pt., pressing and cooling - Google Patents

Abstract

Waste is recovered by shredding the waste pieces, laying them in a layer, heating the layer to a temp. above the m.pt. of the thermoplastics material, compressing the layer and cooling the compressed mass. Used esp. for recovering waste from carpets used in motor vehicle upholstering and consisting of two groups, tufted and a needled felt one. Tufted carpets consist of a polyester backing which supports a polyamide pile held by a polyethylene layer and provided with a cotton undercover. Needled felt has a pile formed from a mixt. of polyamide and polypropylene fibres also held in situ by a polyethylene layer and provided with a cotton undercover.

Description

Process for recycling textile waste

Fall in the manufacture of textile lining parts for cars large amounts of textile waste, which are due to their very heterogeneous composition these lining parts could not be reused meaningfully so far. This waste have been incinerated or dumped so far.

There are two major groups of auto carpets that make up the lining parts getting produced. One consists of tufted carpets, which usually consist of one Pile layer made of continuous polyamide fibers, a carrier fleece made of polyester fibers, a Back coating made of polyethylene and a cover fleece made of rayon are.

The other group are needle felts, the pile layer of which is usually consists of a mixture of polyamide and polypropylene fibers. The back coating is also made of polyethylene with a fleece made of viscose wool.

The aim of the present process is this heterogeneous waste to be used for economic purposes.

The method is characterized in that the textile waste cut, the snippets arranged in a layer, above the melting point of a Part of the thermoplastic components are heated, pressed and cooled.

After cooling, pressed parts are obtained in this way the melted thermoplastic components of the Wastes exist in which the unmelted fibrous portions are firmly embedded are.

Under the cutting of the textile waste there is a shredding on To understand pieces of about 0.5 to 3 cm in size. The waste can also be ripped will.

However, this often results in higher temperatures at which the polyethylene backing coating softened.

This then leads to sticking and malfunctions in the tearing machine. The average size of the shredded textile waste depends on the desired layer thickness of the pressed parts. The thinner the pressed parts are to be, the more The carpet waste has to be cut smaller to form a coherent layer or to give bulk. This cut textile waste is mixed well, then arranged into a layer evenly high and without defects, the uniform height usually by applying an excess and wiping off or doctoring off the excess is achieved.

The materials from which the car carpets are made show very different melting or. Softening points. Polyethylene already has Sufficient flowability at 160 OC, especially when the pressure is applied for a longer period of time is maintained. Polypropylene only shows this flow behavior at temperatures over 180 OC. Polyamide and polyester fibers melt at temperatures above approx. 260 OC and rayon is infusible. This very different behavior in particular against the influence of temperature is exploited in the present process by the cut carpet waste is heated to a temperature at which a proportion from 2 to 75% by weight, preferably 10-70% by weight, has not yet melted.

This unmelted fiber portion forms after the pressed body has cooled down a reinforcing framework in the compact. These are at break edges of pressed bodies unmelted, reinforcing fibers clearly visible.

The temperatures used are between 160 Oc and 260 OC. With the usual composition of car carpets, there is always a sufficiently large one Proportion of polyethylene and polypropylene are present in order to avoid the higher-melting fiber proportions to be able to integrate well. Of course, the procedure can also be used if, for example, the textile waste consisted only of polyamide fibers and wool. In this However, the temperature would have to exceed the melting point of the polyamide fibers can be increased.

The procedure remains equally applicable if instead of the now customary Polyethylene back coatings those made from plasticized PVC or other thermoplastic Masses should arise.

The carpet waste can be heated in a hot press. Included result in relatively long pressing times at low temperatures. Another way of doing things is the heating of the carpet waste outside the press. The preheated carpet waste are then placed in the cold or only moderately heated press and can be used in short pressing times are formed into the pressed parts.

A special embodiment of the process which results in pressed parts with much higher strengths is that the cut textile waste arranged in a layer between glass fleeces, then heated, pressed and cooled.

In this embodiment, the molten thermoplastic fill Shares the voids between the Glass fibers of the glass fleece. After cooling, the glass fibers are firmly integrated into the surface of the pressed parts and form a very stable reinforcement. Instead of the glass fleece, glass fabric can also be used or fiber mats made of continuous fibers or staple fibers are used. Important for the good strengthening effect is the high tensile strength of the fibers and the low Elongation, which is particularly characteristic of fibers made of inorganic material. The glass fleece may or may also be bound with crosslinked or thermoplastic binders consist of unbound fiber layers. For deformable pressed parts are unbound or very weakly or thermoplastically bonded glass fleeces are preferred. The weight ratio the textile waste for the glass fleeces is 65:35 to 98/2, preferably 80 to 20 to 95 to 5.

The pressing of those arranged between glass fleeces and above the melting point the thermoplastic parts heated scraps from textile waste takes place in conventional presses or between rollers. The press jaws or rollers can be heated or be cold.

The pressed parts produced according to the process have densities of approx. 0.5 to 1.1, preferably 0.6 to 1.05. Depending on the chosen proportions from easily meltable to difficult or infusible fibers, the melting temperature, the pressing pressure and the pressing time are pressed parts with more or less pronounced Pore structure and higher or lower density obtained.

The following examples are intended to illustrate the process according to the invention explain in more detail.

Starting material A consists of a needle felt with the following composition: approx. 200 g / m22 polyamide fibers = approx. 16% by weight approx. 450 g / m2 polypropylene fibers = approx. 37% by weight approx. 350 g / m2 polyethylene backing = approx. 29% by weight approx. 20 g / m2 Spun rayon = approx. 2% by weight approx. 200 g / m2 non-crosslinked binder = approx. 16% by weight starting material B consists of a tufted carpet with the following composition: 2 approx. 400 gim Polyamide fibers = approx. 37% by weight approx. 150 g / m2 polyester fibers = approx. 14% by weight approx. 500 g / m polyethylene coating = approx. 47% by weight approx. 20 g Im2 viscose wool = approx. 2% by weight A press with a heatable area of 17 by 17 cm was used for the tests.

Example 1 Carpet waste from starting material A turns into snippets cut from approx. 1 cm edge length, 2 to a uniformly high layer of approx. 3500 g / m poured and in the press heated to 160 ° between silicone paper Pressed for 1 min. At a pressure of 30 bar. A plate of approx. 4.6 mm is obtained Thickness and a density of about 0.58. When breaking the plate is at the break edges to recognize that only the polyethylene has become effective for the bond. The others Substances are unmelted.

Example 2 The procedure is as in Example 1, only the temperature the press is increased to 180 °. A sheet approximately 4.1 mm thick is obtained and a density of 0.67. The appearance of the breakline is similar to that of the Example 1.

Example 3 The procedure is as in Example 1, only the temperature the press is increased to 200 °. A plate about 0.5 mm thick is obtained and a density of about 0.9. Much of the melted thermoplastic Material flows sideways out of the pressure zone. When breaking the plate are the rayon and polyamide fibers of the sheet can be seen at the broken edges as inner reinforcement give increased strength. The polyethylene and polypropylene form a compact mass.

Example 4 Using starting material B in a cracked form proceed as in example 1. A stable plate about 5 mm thick is obtained and a density of 0.55. The plate is only through the melted polyethylene parts bound.

Example 5 The procedure in Example 4 is followed. The temperature of the The press is increased to 200 °. A sheet approximately 4.5 mm thick is obtained and a density of 0.56. The appearance of the breakline is as in the example 4th

Example 6 The procedure in Example 4 is followed. The temperature of the Press is 240 0. A sheet is obtained that is approximately 2.1 mm thick and has a density of 0.61.

Some of the melted thermoplastic fractions are out of the pressure zone flowed off laterally.

The fibrous structure is clearly recognizable from the break edges.

Example 7 2 On a glass fleece of 53 g / m 2, a uniformly high Layer of snippets of the starting material A applied in an amount of approx. 3500 g / m. This layer is covered with a second glass fleece of 53 g / m 2 and exposed to a pressure of 30 bar for 1 minute in a press heated to 160 °. A sheet approximately 4.3 mm thick and with a density of 0.67 is obtained. The liquid one Polyethylene has the voids between the individual glass fibers of the glass fleece filled in and the two glass fleeces are firmly embedded in the plastic. The plate has a significantly increased stability compared to the plate according to example 1.

Example 8 The procedure is as in Example 7, but the temperature the press is 180 ° and the chips are between two layers of glass fleece 53 g / m each above and below.

A sheet about 4.1 mm thick and with a density of 0.71 is obtained. The glass fleece is completely embedded in the plastic. The plate is very stable.

The same fibrous structure can be seen at the break edges as at Examples 1 and 2.

Example 9 The procedure is as in Example 7, but the snippets are placed between 3 fleece layers of 53 g / m above and below. The temperature the press is 200 0. A large part of the melted thermoplastic components emerges from the side of the pressure zone. A plate with a thickness of 0.9 mm is obtained a density of approx. 1.05. The glass fleece is completely embedded in the thermoplastic.

Example 10 2 2 glass fleeces of 53 μm each are placed on top of one another, then a bed of approx. 3500 g of cracked starting material B was evenly applied and then covered with 2 glass fleeces of approx. 53 g / m each. This layer structure is pressed in a press heated to 160 ° for 1 minute at 30 bar. You get one very stable plate with a thickness of approx. 5.6 mm and a density of approx. 0.55. The glass fleeces are completely embedded in the melted thermoplastic.

Example 11 Proceed as in Example 10, but it only becomes a layer of glass fleece above and below and a bed of approx. 5250 g / m torn material B in between. The temperature of the press is 180 °.

It becomes a plate with a thickness of approx. 8 mm and a density received from o.64.

Example 12 The procedure is as in Example 10, but each will be three glass fleeces above and below and a fill of approx. 1750 glm des cracked starting material B. The temperature of the press is 240 0.

A plate with a thickness of approx.

2.7 mm and a density of approx. 0.7. The fiber optics are here too completely embedded in the thermoplastic material. Part of the thermoplastic Material flowed out of the pressure zone during pressing.

Example 13 In order to carry out the process according to the invention with a cold press and To carry out short pressing times, the procedure was as follows. A layer structure As in Example 8, made of 2 layers of glass fleece above and below and approx. 2000 g / m snippet of the starting material A is covered with several layers of paper at the top and bottom and heated to 235 ° in a drying cabinet for about 15 minutes. The hot material will Put it in the cold press within a few seconds of taking it out of the drying cabinet inserted and the press closed with a pressure of approx. 3 bar.

After a pressing time of 10 seconds, a plate of approx.

2.15 mm thick and a density of approx. 1.0. The glass fleece are completely embedded in the thermoplastic material. The plate is very stable.

Example 14 The procedure is as in Example 13, but starting material A and B are mixed in a ratio of 1: 1.

A very stable plate with a thickness of approx. 2.6 mm is obtained and a density of about 0.85. The outer glass fleeces are in individual places not completely embedded in the thermoplastic material.

Claims (2)

Claims 1. Process for recycling textile waste characterized in that the textile waste is cut and the cut Waste arranged in a layer above the melting point of part of the thermoplastic Shares are heated, pressed and cooled. 2. The method according to claim 1, characterized in that the cut textile waste arranged in a layer between glass fleece, above the melting point Part of the thermoplastic components are heated, pressed, and the glass fleece embedded in the thermoplastic material and cooled.