EP1476241A2

EP1476241A2 - Heat sealing filter materials

Info

Publication number: EP1476241A2
Application number: EP03742544A
Authority: EP
Inventors: Günter Heinrich; Manfred Kaussen; Martin Business Development & Strategical BÜCHSEL
Original assignee: Papierfabrik Schoeller and Hoesch GmbH and Co KG; Schoeller und Hoesch GmbH
Current assignee: Schoeller und Hoesch GmbH; Glatfelter Gernsbach GmbH and Co KG
Priority date: 2002-02-19
Filing date: 2003-02-19
Publication date: 2004-11-17
Also published as: JP2005517767A; US20080211122A1; CN1533343A; CA2435578A1; JP4571411B2; US7344034B2; RU2003128071A; US8163131B2; WO2003070353A2; DE10206924B4; US20040089602A1; DE10206924A1; AU2003215568B2; US20110193250A1; US7905985B2; WO2003070353A3; AU2003215568A1; ZA200307300B

Abstract

Disclosed are a filter material containing heat sealing, biodegradable, and compostable polymer fibers in addition to 0.5 to 5.0 percent by weight of a lubricant, the percentage being in relation to the paper weight of the finished filter material, and methods for the production thereof.

Description

HOT SEALABLE FILTER MATERIALS

description

The present invention relates to a heat sealable filter material with excellent hot water resistance and biodegradability, which contains fibers made of a heat sealable, biodegradable and compostable material and a lubricant.

It is known to pack tea or other fillings in bags that are brewed for use with hot water. These bags usually consist of a first layer of a porous material made of natural fibers and a second layer of hot-melting polymer fibers such as PP, PE or various copolymers. This second layer is used to close the bag by heat sealing on tendon-wrapping machines.

This bag material can be produced in a known manner according to a wet-laid process on a paper machine, a dry-laid process on a fleece laying machine or a melt-blown process by depositing polymer aers on a carrier layer ^ L- \

The first lag "E: the material generally has a basis weight of 8-40 g / m ^2, preferably 10-20 g / m ^2, the second polymer fiber layer has a basis weight of 1-15 g / m ^2, vorzugseise _1/5 -10 g / m ² .

It is known that the used filter bags are disposed of on a compost heap or via the organic waste bin. After a certain period of time, which depends on other parameters such as temperature, humidity, microorganisms etc., the natural fiber component of the filter bag has disintegrated and biodegraded, while the thermoplastic polymer fiber network is preserved and the quality of the composite is reduced.

A separation of the natural fiber component from the thermoplastic polymer component is not practical, ie the used filter bag would have to be added to the non-recyclable waste (gray bin). EP-A-0 380 127 describes a heat-sealable tea bag paper with a basis weight of 10-15 g / m ² , which is provided with polymers such as PP, PΞ or a copolymer for heat sealing and is therefore not biodegradable.

EP-A-0 656 224 describes a filter material, in particular for the production of tea bags and coffee bags or filters with a basis weight between 8 and 40 g / m ² , in which the heat-sealable layer consists of plastic fibers, preferably of polypropylene or Polyethylene, which is placed in a softened state on the first layer made of natural fibers.

JP-A-2001-131826 describes the production of biodegradable monofilaments from poly-L-lactide and the subsequent production of fully synthetic tea bags woven therefrom using a dry-laid process.

German patent application DE-A 21 47 321 describes a thermoplastic, heat-sealable composition which consists of a polyolefin powder (polyethylene or polypropylene) which is embedded in a carrier matrix made of vinyl chloride / vinyl acetate copolymer. This material is also used for the heat-sealable finishing of paper-based fiber material.

DE-A-197 19 807 describes a biodegradable heat-sealable filter material that consists of at least one layer of natural fibers and at least a second layer of heat-sealable synthetic material that is biodegradable. This filter material is obtained by applying on a wire in a first step as aqueous suspension, the natural fibers and the heat-sealable, biodegradable polymer fibers are deposited on the natural fiber layer ^■ such in a second stage that they can penetrate the natural fiber layer partially.

With a tea filter bag made from this filter material, for example, the possibility of high particle retention is created. However, this is "bought" by a reduced air permeability. However, a high air permeability with good particle retention is the goal of an optimal filter material. The filter materials known from the prior art thus suffer from at least one of the following disadvantages:

1. The used filter materials such as Tea bags, coffee bags or other filters are often disposed of in a compost heap or in the organic waste bin. After a certain period of time, which depends on other parameters such as temperature, air humidity, microorganisms, etc., the natural fiber component of the filter has disintegrated and biodegraded, while the thermoplastic polymer fiber network of polymer fibers that are not completely biodegradable is retained and the quality of the compost is reduced.

And or

2. The use of completely biodegradable polymer materials for tea bags and similar filter papers known from the prior art means that the heat-sealed seams formed on the tea bags do not withstand a temperature of approximately 90-100 ° C.

This is due to the fact that filled, heat-sealed tea bags are produced on fast-running packaging machines with a cycle time of around 1000 bags per minute.

So-called heat-sealing rollers generally seal the bag at a temperature of 150-230 ° C in a cycle time of less than 1 second. With these short cycle times, the heat-sealing material must melt, adhere to one another and immediately solidify and crystallize again so that the bag is closed again during further transport and no filling material can escape.

However, as mentioned above, the prior art materials do not meet the requirements of this process.

It was therefore an object of the present invention to provide a biodegradable and compostable filter material with excellent heat sealability and good seal seam strength in the dry and wet state. In addition, a method for producing such filter materials will be described.

Surprisingly, it has now been found that, with the use of special lubricants, the disadvantages of the filter materials of the prior art described above can be overcome and filter materials can be provided which are biodegradable and compostable and at the same time provide excellent properties with regard to heat sealability and seal seam strength.

The present invention relates to a filter material which contains fibers from a heat-sealable, biodegradable and compostable material and is characterized in that it additionally contains a lubricant in an amount of 0.5 to 5.0% by weight, based on the weight of the paper of the finished filter material.

The combined use of the heat-sealable, biodegradable and compostable polymer fibers and the lubricant in the stated amount gives the filter material according to the invention the property that, using the filter material according to the invention (as described above), heat-sealing seams formed with the aid of a heat-sealing roller are extremely stable in hot water. The term “hot water stable” here means according to the invention a resistance or integrity of a heat seal seam of a filter bag made from the filter material according to the invention during the brewing process for 4 minutes.

In a preferred embodiment, the filter material according to the invention can be heat-sealed by ultrasound treatment.

By the term "biodegradable and compostable polymer fibers" that are used according to the invention, we mean completely biodegradable and compostable polymer fibers according to DIN 54900.

The lubricants which can be used according to the invention are compounds which lead to better sliding behavior of the polymer fibers and thus support and improve the gathering and the orientation of crystalline zones. This increases the proportion of crystalline zones in the polymer fibers. Such lubricants are well known to those skilled in the art. It can be hydrocarbon oils or waxes or silicone oils. In a preferred embodiment, the lubricants which can be used according to the invention consist of fatty acid esters of long-chain fatty acids with a chain length of 10 to 40 carbon atoms, for example around a fatty acid ester sold by Henkel with the name Loxiol.

The lubricant is preferably present in the filter material according to the invention in an amount of 1.0 to 3.0% by weight.

Without wishing to be bound by any theory, the inventors of the present invention currently assume that the use of a lubricant promotes rapid recrystallization of the polymer fibers, which is particularly necessary and helpful for the heat-sealing strength, so that neighboring fibers in the fabric close as quickly as possible find comparable crystallization zones, which then become more pronounced. -

In a preferred embodiment, the filter material according to the invention further contains a seed material which supports the crystallization of the fibers from the heat-sealable, biodegradable and compostable material during the heat sealing.

According to the invention, inorganic materials such as talc, kaolin or similar materials are suitable as the seed material, usually in finely divided form.

The particle size of the seed material is usually 0.1 to 5 μm.

The amount of the seed material added is usually 0.01 to 1.0% by weight.

According to the invention, the starting materials for the fibers made of the heat-sealable, biodegradable and compostable material are fibers made of polymers which are selected from the group of aluminum phatic or partially aromatic polyester amides and aliphatic or partially aromatic polyesters are selected.

Specifically, these are the following polymers:

Aliphatic or partially aromatic polyester:

A) from aliphatic ^' bifunctional alcohols, preferably linear C ₂ to C ₁₀ dialcohols such as ethanediol, butanediol, hexanediol or particularly preferably butanediol and / or ^' optionally cycloaliphatic bifunctional alcohols, preferably having 5 or 6 carbon atoms in the Cycloaliphatic ring, such as cyclohexanedimethanol, and / or partially or completely instead of the diols, monomeric or oligomeric polyols based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof with molecular weights up to 4000, preferably up to 1000, and / or optionally small amounts of branched bifunctional alcohols, preferably C ₃ -C ₂ -alkyldiols, such as neopentyl glycol, and additionally, if appropriate, small amounts of higher-functional alcohols such as 1, 2, 3-propanetriol or trimethylolpropane and from aliphatic bifunctional acids, preferably C ₂ - C ₁₂ alkyl dicarboxylic acids, such as se and preferably succinic acid, adipic acid and / or optionally aromatic bifunctional acids such as, for example, terephthalic acid, phthalic acid, naphthalenedicarboxylic acid and additionally optionally small amounts of higher functional acids such as trimellitic acid or

B) from acid- and alcohol-functionalized building blocks, preferably with 2 to 12 carbon atoms in the alkyl chain, for example hydroxybutyric acid, hydroxyvaleric acid, lactic acid, or their derivatives, for example ε-caprolactone or dilactide,

or a mixture and / or a copolymer containing A and B,

the aromatic acids making up no more than 50% by weight, based on all acids.

Aliphatic or partially aromatic polyester amides: C) from aliphatic bifunctional alcohols, preferably linear C ₂ to C ₁₀ dialcohols such as ethanediol, butanediol, hexanediol or particularly preferably butanediol and / or optionally cycloaliphatic bifunctional alcohols, preferably having 5 to 8 carbon atoms in the cycloaliphatic ring , such as cyclohexanedimethanol, and / or partially or completely instead of the diols, monomeric or oligomeric polyols based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof with molecular weights of up to 4000, preferably up to 1000, and / or possibly low Amounts of branched bifunctional alcohols, preferably with C ₂ -C ₁₂ alkyl dicarboxylic acids, such as neopentyl glycol and, if appropriate, small amounts of higher functional alcohols such as 1, 2, 3-propahtriol, trimethylolpropane and aliphatic bifunctional acids such as and preferably succinic acid, adipic acid Acid and / or optionally aromatic bifunctional acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and additionally optionally small amounts of higher functional acids such as trimellitic acid or

D) from acid and alcohol-functionalized building blocks, preferably with 2 to 12 carbon atoms in the carbon chain, for example hydroxybutyric acid, hydroxyvaleric acid, lactic acid or their derivatives, for example ε-caprolactone or dilactide,

or a mixture and / or a copolymer containing C) and D),

the aromatic acids making up no more than 50% by weight, based on all acids,

E) an amide content of aliphatic and / or cycloaliphatic bifunctional and / or optionally small amounts of branched bifunctional amines, linear aliphatic C ₂ to C ₁₀ diamines are preferred, and additionally optionally small amounts of higher functional amines, among the amines preferably hexamethylenediamine, iso - ph.orondia.min and particularly preferably hexamethylenediamine, and from linear and / or cycloaliphatic bifunctional acids, preferably with 2 to 12 carbon atoms in the alkyl chain or C ₅ - or C ₃ ring in the case of cycloaliphatic acids, preferably adipic acid , and / or optionally small amounts of branched bifunctional and / or optionally aromatic bifunctional acids such as for example terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and additionally optionally small amounts of higher functional acids, preferably with 2 to 10 carbon atoms, or

F) from an amide portion of acid- and amine-functionalized building blocks, preferably with 4 to 20 carbon atoms in the cycloaliphatic chain, preferably ω-laurolactam, ε-caprolactam, particularly preferably ε-caprolactam,

or a mixture containing E) and F) as an amide component, wherein

the ester fraction C) and / or D) is at least 20% by weight, based on the sum of C), D), E) and F), preferably the weight fraction of the ester structures is 20 to 80% by weight, the fraction of Amide structures is 80 to 20% by weight.

All monomers mentioned as acids can also be used in the form of derivatives such as acid chlorides or esters, both as monomers and as oligomeric esters.

The synthesis of the biodegradable and compostable polyester amides used according to the invention can be carried out either by the "polyamide method" by stoichiometric mixing of the starting components, if appropriate with the addition of water and subsequent removal of water from the reaction mixture, or by the "polyester method" by stoichiometric mixing of the Starting components and addition of an excess of diol with esterification of the acid groups and subsequent transesterification or transamidation of these esters. In this second case, the excess diol is distilled off in addition to water. The synthesis according to the described "polyester method" is preferred.

The polycondensation can be further accelerated by using known catalysts. Both the known phosphorus compounds, which accelerate polyamide synthesis, and acidic or organometallic catalysts for the esterification, as well as combinations of the two, are possible for accelerating the polycondensation. Care must be taken to ensure that the catalysts used, if any, do not have a negative effect on the biodegradability or compostability or the quality of the resulting compost.

Furthermore, the polycondensation to polyesteramides can be influenced by the use of lysine, lysine derivatives or other amidically branching products such as, for example, aminoethylaminoethanol, which both accelerate the condensation and lead to branched products (see, for example, EP-A-0 641 817; DE -A-38 31 709).

The production of polyesters is generally known or is carried out analogously by known processes (cf. e.g. EP-A-0 592 975).

The polyesters or polyester amides used according to the invention may further contain 0.1 to 5% by weight, preferably 0.1 to 3% by weight, in particular 0.1 to 1% by weight, of additives, based on the polymer ( see also description of the polymers). Examples of these additives are modifiers and / or fillers and reinforcing materials and / or processing aids such as, for example, nucleating aids, customary plasticizers, mold release aids, flame retardants, impact modifiers, colorants, stabilizers and other additives customary in the field of thermoplastics, with a view to the requirement of Biodegradability, care must be taken to ensure that the compostability is not impaired by the additives and that the additives remaining in the compost are harmless.

The biodegradable and compostable polyesters and polyester amides generally have a molecular weight of 5,000 to 500,000 g / mol, advantageously 5,000 to 350,000 g / mol, preferably 10,000 to 250,000 g / mol, determined by gel chromatography (GPC), for example in m Cresol against a polystyrene standard. In the case of copolymers, the biodegradable and compostable polymers preferably have a statistical distribution of the starting ^monomers .

In ^"a preferred embodiment, the fibers in the heatsealable, biodegradable and compostable Material around stretched, heat sealable, biodegradable and compostable polymer fibers.

^'Those stretched according to the invention, heat-sealable, biodegradable and compostable polymeric fibers usually have a linear density (DIN 1301, TI) of 0.1 to 10 dtex, preferably 1.0 to 6 dtex.

In the filter material according to the invention, these are usually in an amount of 0.05 to 50% by weight, based on the paper weight of the finished filter material, advantageously in an amount of 0.1 to 45% by weight and preferably in an amount of 1 , 0 to 35% by weight.

The stretched, heat-sealable, biodegradable and compostable polymer fibers which can be used according to the invention usually have a stretching ratio of 1.2 to 8, preferably 2 to 6. The crystallization of the polymer fibers induced by this stretching increases the resistance of these fibers after the heat sealing to boiling water.

The draw ratio was determined according to the invention in a manner generally known to the person skilled in the art in the relevant field.

The stretching ratio required according to the invention can be set in the production of the polymer fibers which can be used according to the invention by producing the polymer fibers by a melt spinning process on commercially available spinning systems in such a way that polymer fibers having a stretching ratio of 1.2 to 8, preferably 2 to 6, are obtained. The following parameters have proven to be favorable process parameters for the production of preferred stretched polymer fibers which can be used according to the invention:

Spinning temperature: 180 to 250 ° C, preferably 190 to 240 ° C;

- Cooling air temperature: 10 to 60 ° C, preferably 20 to 50 ° C;

- Hot drawing at 85 to 180 ° C, preferably 120 to 160 ° C. Usually, a hydrophilic substance is also used in the drawing of the polymer fibers in order to improve the water absorption due to their wetting properties.

In a preferred embodiment the polymer fibers are drawn after drawing, i.e. after receipt on the spinning system, further thermally fixed. This serves to minimize shrinkage of the stretched polymer fibers. This thermal fixation is usually carried out by thermal treatment of the stretched polymer fibers at temperatures from 10 to 40 ° C. below the respective melting point of the polymer fibers.

The stretched polymer fibers obtained are furthermore usually cut to a length of 1 to 20 mm, advantageously 1 to 10 mm and preferably 2 to 6 mm before incorporation of the stretched polymer fibers in the course of the filter material production process. This cutting of the polymer fibers obtained is usually carried out with commercially available cutting tools for filaments.

In a preferred embodiment, the starting materials for the drawn polymer fibers are polyester amides with an ester content of 40 to 65% by weight and an amide content of 35 to 60% by weight, for example a polyester amide from AH salt, adipic acid , Butanediol with an amide content of 60% by weight and an ester content of 40% by weight and a mass-average molecular weight of 19,300 (determined by means of GPC in m-cresol against polystyrene standard).

In a particularly preferred manner, according to the invention, the starting materials used for the stretched polymer fibers are those with a moisture content of 0.1% by weight or less, based on the starting material polymer, preferably those with a moisture content of 0.01% by weight or less to prevent disturbances when spinning and stretching the polymer fibers.

In addition to the fibers of a heat-sealable, biodegradable and compostable material, the filter materials according to the invention contain Ren material natural fibers and / or cellulose derivative fibers in an amount of 50 to 99.95 wt .-%, based on the paper weight of the finished filter material, advantageously in an amount of 65 to 99.9 wt .-% and preferably in an amount of 80 up to 99.5% by weight.

The natural fibers which can be used according to the invention are the natural fibers known to the person skilled in the relevant art, such as hemp, manila, jute ^' , sisal and others, and long-fiber wood pulp.

An embodiment of the filter materials according to the invention and their production are described in more detail below.

In general, in addition to the fibers of a heat-sealable, biodegradable and compostable material and the lubricant, the filter materials according to the invention comprise at least one further component which comprises or preferably consists of natural fibers.

In this preferred embodiment of the present invention, the filter material according to the invention is thus produced from two or more layers of different components, at least one layer containing natural fibers and one layer containing a fiber blend of fibers made from a heat-sealable, biodegradable and compostable material and lubricant, that the at least two layers can partially penetrate one another after the filter material has been produced. The degree of penetration of the layers can be controlled by the manufacturing process of the filter material, for example in the case of using a paper machine by adjusting the degree of dewatering on the screen.

In the case of the production of the filter material according to the invention on the paper machine, the second layer usually comprises a fiber blend made of natural fibers, fibers made of a heat-sealable, biodegradable and compostable material and lubricants. This can be placed on the paper machine on the first layer made of natural fibers and can be fused to one another as well as to the paper layer. In the case of the production of the filter material according to the invention by the meltblown process, the second layer usually comprises a fiber blend of fibers made from a heat-sealable, biodegradable and compostable material and lubricant. This can be deposited on the first layer of natural fibers using the meltblown method and can be fused both to one another and to the paper layer.

The first layer of the filter material generally has a basis weight between 8 and 40 g / m ² , preferably from 10 to 20 g / m ² and an air permeability of 300 to 4000 l / m ² "s (DIN ISO 9237), preferably of 500 up to 3000 l / m ² »s.

The second layer of filter material generally has a weight per unit area between 1 and 15 g / m ² , preferably between 1.5 and 10 g / m ² .

The first layer of the filter material with or preferably made of natural fibers is preferably designed to be wet-strength.

Known natural fibers such as hemp, manila, jute, sisal and other long-fiber wood pulps and mixtures thereof are preferably used for the first layer with or preferably made of natural fibers.

The second layer can contain the mixture of fibers from a heat-sealable, biodegradable and compostable material and lubricant, and consist of them. In the case of the production of the filter material according to the invention on the paper machine, the second layer preferably comprises, in addition to the above components, a further component, in particular natural fibers, with mixing ratios of 1/3 natural fibers and 2/3 mixture of cellulose derivative and polymer fibers being particularly preferred.

The filter material according to the invention can be used, for example, for the production of tea bags, coffee bags or tea or coffee filters.

As stated above, the method for producing the filter materials according to the invention can be controlled in such a way that the biodegradable and compostable heat-sealable fibers of the partially penetrate the first layer and envelop the fibers of the first layer, preferably the natural fibers of the first layer, thus in the molten state during the drying process, for example on the paper machine. However, according to the invention, the pores necessary for filtration are left free.

A manufacturing method which can be used according to the invention is explained in more detail below with reference to the figures using the example of a two-layer filter material.

Here, FIG 1 ^'shows. The various stages in the formation of the filter material of the invention from natural fibers and synthetic fibers for the example of the use of a paper machine in a general, roughly schematic representation.

In Fig. 1, the formation of the filter material according to the invention is shown in a schematic representation. La) shows the formation of a first fiber layer from natural fibers 1 and the formation of a second fiber layer with synthetic, biodegradable and compostable heat-sealable fibers 2. The formation of the second layer with the fibers 2 thus takes place by deposition over the first layer, which is formed by the natural fibers 1. In the drawing, the natural fibers 1 are hatched horizontally to distinguish them, while the heat-sealable fibers 2 have been hatched approximately vertically.

Fig. Lb) shows how a partial penetration of the two layers is achieved by the described dewatering of the two layers, in particular the second layer with the fibers 2, so that the synthetic fibers 2 get between the natural fibers 1.

In a further production step, the partially penetrating layers 1 and 2 are dried and heated in such a way that the synthetic fibers 2 melt and, during re-consolidation, lay around the fibers 1 in such a way that they are at least partially covered. The filter material has thus become heat sealable (Fig. Lc).

Fig. 2 shows the basic structure of a paper machine, as used for producing a filter material according to the invention can be. First, a suspension "A" is formed from the ground natural fibers and water. In addition, the fiber blend is used to produce a suspension "B" from fibers from a heat-sealable, biodegradable and compostable material and lubricant and, if appropriate, a proportion of other fibers, for example natural fibers, and water.

These two suspensions A and B are fed from the respective containers (3 and 4) via the so-called headbox to the paper machine. This essentially has a peripheral sieve (5) which is passed over a number of dewatering chambers (6, 7 and 8).

The suspension 'A is passed onto the screen 5, via the first two dewatering chambers 6, via suitable pipelines and pumping devices, which are not shown in more detail, the water being sucked off through the chambers 6 and the dewatering line. A first fiber layer of natural fibers 1 is formed on the moving sieve 5. When the sieve 5 moves further over the dewatering chambers 7, the second suspension B is supplied, the second layer of synthetic fibers being deposited over the dewatering chambers 7 on the first layer , The drainage takes place via the drainage line. During the further movement of the screen 5 with the two fiber layers lying on top of each other, dewatering is carried out via the dewatering chambers 8, as a result of which the two layers partially penetrate one another. By setting the drainage accordingly, the penetration can be more or less strong.

The material 9 now formed from natural fibers and polymer fibers is removed from the sieve and fed to drying. This drying can be done in different ways, e.g. B. by contact drying or Durchströmmedrockήung.

The elements 10 only give a rough schematic indication of corresponding drying elements.

In Fig. 2 3 drying cylinders 10 are drawn, over which the shaped paper web is dried in the contact process. However, it is also practicable to guide the paper web formed over only one cylinder. and dry them with hot air without the web resting on this cylinder.

The heating of the two-layer fiber material causes the synthetic fibers 2 in the mixed layer 9 to melt. During the re-consolidation at the exit of the drying station, the synthetic fibers at least partially envelop the natural fibers and the heat-sealable filter material is rolled up on a roll 11.

The biodegradable and compostable filter material according to the invention can also be produced by the meltblown process, as described below for a two-layer filter material:

If the mixture of biodegradable and compostable polymer and lubricant which forms the second layer is in the form of granules, it can be shaped into fibers using the melt-blown (meltblown fibers) process and in the hot-hot adhesive state on a base, e.g. B. a paper made of natural fibers.

This process is part of the prior art (see, for example, EP-A-0 656 224, DE-A-197 19 807), but nevertheless the basics of the method shown in FIG. 3 will be briefly discussed:

The dried granulate 12 is transported to an extruder 13, in which it is melted and heated to the temperature required for fiber formation. This molten and heated mixture then reaches the MB nozzle 14. This nozzle has a large number of small openings through which the molten polymer mixture is pressed and drawn into fibers. These fibers 15 are captured directly below this nozzle by a strong air stream, stretched further, torn into different lengths and placed on a base, e.g. B. a paper made of natural fibers 16, which lies on a suction roller 17, filed. Since these fibers are still hot and sticky, they stick to the natural fibers of the paper. The material is then rolled up on the winder 18 in the cooled state. The typical diameter of these meltblown fibers is between 2 and 7 μm. 3 is a schematic representation of the meltblown process. Example 1 :

First, a single-layer, approx. 13 g / m ² filter material made of natural fibers was produced on the paper machine using the wet laying process. (Mixture of 35% by weight of manila fibers and 65% by weight of softwood pulp). The filter material was made wet-proof.

The above-described filter material with approximately 3.5 g / m ^{2 of} biodegradable polymer fibers and a lubricant (Loxiol / Fa. Henkel) was then run on a conventional, state-of-the-art melt-blown system with a running speed of approximately 130 m / min coated. (99.5% biodegradable polyester amide, 0.5% loxiol). The temperatures at the individual zones of the spinnerets in this test were 224-227 ° C.

Tea bags were handmade from this 2-layer filter material and filled with 1.9 g of tea. These manufactured tea bags were then sealed on all four sides with a commercially available sealing device from RDM type HSE-3. Parameters: temperature: 210 ° C

Time: 0.5 sec.

Pressure: 3 bar

Infusion test: Three arbitrarily selected tea bags made according to the above description were poured with boiling water and allowed to steep for 4 minutes.

No bag opened.

Example 2:

The experiment described above was continued under the same conditions, but with a changed polyester amide-loxiol content. a. 99% biodegradable polyester amide, 1% loxiol b. 98% biodegradable polyester amide, 2% loxiol

Result of the infusion test:

No bag opened. As a comparison, a filter material was produced according to the above information, but instead of the biodegradable heat-sealable polymer fibers, a non-biodegradable vinyl chloride / vinyl acetate copolymer was used.

In the infusion test described above, none of the three bags made from it opened.

Claims

claims

1. Filter material which contains heat-sealable, biodegradable and compostable polymer fibers and is characterized in that it additionally contains a lubricant in an amount of 0.5 to 5.0% by weight, based on the paper weight of the finished filter material.

2. Filter material according to claim 1, wherein the heat-sealable, biodegradable and compostable polymer fibers are selected from the following group of polymers:

Aliphatic or partially aromatic polyester:

A) from aliphatic bifunctional alcohols, preferably linear C ₂ to C ₁₀ dialcohols such as ethanediol, butanediol, hexanediol or particularly preferably butanediol and / or optionally cycloaliphatic bifunctional alcohols, preferably with 5 or 6 carbon atoms in the cycloaliphatic ring, such as for example cyclohexanedimethanol, and / or partially or completely branched instead of the diols monomeric or oligomeric polyols based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof with molecular weights up to 4000, preferably up to 1000, and / or optionally small amounts bifunctional alcohols, preferably C ₃ -C ₁₂ alkyldiols, such as neopentyl glycol, and additionally, if appropriate, small amounts of higher functional alcohols such as 1, 2,3-propanetriol or triethylolpropane, and from aliphatic bifunctional acids, preferably C ₂ -C ₁₂ - Alkyldicarboxylic acids, such as and be preferably succinic acid, adipic acid and / or optionally aromatic bifunctional acids such as for example terephthalic acid, phthalic acid, naphthalenedicarboxylic acid and additionally optionally small amounts of higher functional acids such as trimellitic acid or

or a mixture and / or a copolymer containing A and B, the aromatic acids making up no more than 50% by weight, based on all acids;

aliphatic or partially aromatic polyester amides:

C) from aliphatic bifunctional alcohols, preferably linear C ₂ to C ₁₀ dialcohols such as ethanediol, butanediol, hexanediol or particularly preferably butanediol and / or optionally cycloaliphatic bifunctional alcohols, preferably having 5 to 8 carbon atoms in the cycloaliphatic ring, such as for example cyclohexanedimethanol, and / or partially or completely branched instead of the diols monomeric or oligomeric polyols based on ethylene glycol, propylene glycol, tetrahydrofuran or copolymers thereof with molecular weights of up to 4000, preferably up to 1000, and / or optionally small amounts bifunctional alcohols, preferably with C ₂ _-C ₂ _{-alkyl dicarboxylic} acids, such as neopentyl glycol and additionally optionally small amounts of higher-functional alcohols such as 1, 2, 3-propanetriol, trimethylolpropane and aliphatic bifunctional acids such as and preferably succinic acid, adipic acid re and / or optionally aromatic bifunctional acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and additionally optionally small amounts of higher functional acids such as trimellitic acid or

or a mixture and / or a copolymer containing C) and D),

the aromatic acids making up no more than 50% by weight, based on all acids,

E) an amide portion of aliphatic and / or cycloaliphatic bifunctional and / or optionally small amounts of branched bifunctional amines, linear aliphatic C ₂ to C ₁₀ diamines are preferred, and additionally small amounts of higher functional amines, among the amines preferably hexamethylenediamine, iso- phorondiamine and particularly preferably hexamethylene diamine, and from linear and / or cycloaliphatic bifunctional acids, preferably with 2 to 12 C atoms in the alkyl chain or C ₅ or C ₆ ring in the case of cycloaliphatic acids, preferably adipic acid, and / or optionally small amounts of branched bifunctional and / or optionally aromatic bifunctional acids such as, for example, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and additionally optionally small amounts of higher-functional acids, preferably having 2 to 10 carbon atoms, or

or a mixture containing E) and F) as an amide component, wherein

the ester fraction C) and / or D) is at least 20% by weight, based on the sum of C), D), E) and F), preferably the weight fraction of the ester structures is 20 to 80% by weight, the fraction of the amide structures is 80 to 20% by weight.

3. Filter material according to claim 1 or 2, wherein the filter material further contains a further component comprising natural fibers.

4. Filter material according to one of claims 1 to 3, wherein the filter material is made from two or more layers of different components, at least one layer of natural fibers and one layer of fibers made from a blend of fibers made from a biodegradable and compostable material and a lubricant, with the fact that the at least two layers can partially penetrate each other after the filter material has been produced.

According to any one of claims 1 to 4, wherein the first layer comprises 5 filter material has a basis weight between 8 and 40 g / m ² and an ^'air permeability from 300 to 4000 l / m ² »s (DIN ISO 9237).

6. Filter material according to one of claims 1 to 4, wherein the second layer with the fibers of the biodegradable and compostable material has a basis weight of 1 to 15 g / m ² .

7. Filter material according to one of claims 1 to 6, wherein the first layer consists of natural fibers and is designed to be wet-strength.

8. Filter material according to one of claims 1 to 7, wherein the lubricant is selected from hydrocarbon oils or waxes or silicone oils.

9. Filter material according to claim 8, wherein the lubricant is selected from fatty acid esters of long-chain fatty acids with a chain length of 10 to 40 carbon atoms.

10. A method for producing a filter material, characterized in that a filter material is produced in the course of a wet laying process using a lubricant in an amount of 0.5 to 5.0% by weight, based on the paper weight of the finished filter material.

11. A process for producing a filter material, characterized in that, in the context of a meltblown process, a blend of fibers of a heat-sealable, biodegradable and compostable material and a lubricant in an amount of "0.5 to 5.0% by weight, based on the paper weight of the finished filter material, is usually deposited on a first layer of natural fibers.

12. Use of the filter material according to one of claims 1 to 9 for the production of tea bags, coffee bags or tea or coffee filters.