EP1811852A1

EP1811852A1 - Non-woven fabric and food casing which is produced therefrom and which is based on cellulose hydrate

Info

Publication number: EP1811852A1
Application number: EP05807903A
Authority: EP
Inventors: Klaus-Dieter Hammer; Herbert Gord; Walter Lutz
Original assignee: Kalle GmbH and Co KG
Current assignee: Kalle GmbH and Co KG
Priority date: 2004-11-05
Filing date: 2005-11-02
Publication date: 2007-08-01
Also published as: WO2006048235A1; DE102004053412A1; US20080187735A1

Abstract

The invention relates to a viscose and resin-bound non-woven fabric based on cellulose fibres, which is cross-linked to a urea methoylol having a low-molecular weight and which does not react with itself, which has, preferably, a cyclic structure. The urea methylol is preferably, a 1,3-bis-hydroxymethyl-tetra-hydro-imidazole-2-one (= dimethylol-ethylene-urea), substituted, optionally, in 4- and/or 5-positions, more preferably, 4,5-dihydroxy-1,3-bis-hydroxymethyl-tetrahydro-imidazole-2-one (= dimethylol-dihydroxy-ethylene-urea), a 1,3-bis-hydroxymethyl-5-(C1-C6)alkyl-tetrahydro-1 H-[1,3,5]triazine-2-one, preferably, 1,3-bis-hydroxymethyl-5-ethyl-tetrahydro-1 H-[1,3,5]triazine-2-one (= dimethylol-ethyl-triazinone),1,3-bis-hydroxymethyl-tetrahydro-lH-pyrimidin-2-one (= dimethylol-propylene urea), 5-hydroxy-1,3-bis-hydroxymethyl-tetrahydro-lH-pyrimidine-2-one (= dimethylol-hydroxy-propylene urea) or tetrakis-hydroxy-methyl-tetrahydro-1 H,3H-imidazo[4,5-d] imidazol-2,5-dione (= tetramethylol-acetylene urea). The humidity-resistant non-woven fabric can be used as a reinforcer in food casings based on regenerated or precipitated cellulose, in particular in cellulose fibre skins.

Description

Non-woven fabric and food casing based thereon on cellulose hydrate

The invention relates to a wet-strength and alkali-resistant bonded nonwoven based on cellulosic fibers and a process for its preparation. It also relates to a food casing based on cellulose hydrate, which contains the nonwoven fabric as a reinforcing material. The food casing is intended in particular as an artificial sausage casing.

Tubular casings based on cellulose hydrate with a reinforcement made of a non-woven fabric, which are also referred to as cellulose fiber casings, have proven themselves for a long time. In the production of the cellulose fiber casings, a fiber fleece or fiber paper, preferably a hemp fiber paper, is generally first formed into a tube. The hose is then exposed from the outside, from the inside or from both sides with viscose. He then goes through an acidic spinning bath in which the viscose is coagulated and regenerated to cellulose. The fiber paper tube is finally completely covered on one or both sides with a layer of cellulose hydrate.

The fiber paper need not necessarily be formed into a tube. It is also known to coat a fiber paper in the flat state with viscose and then to coagulate the viscose in spinning and washing baths and finally to regenerate cellulose hydrate. The cellulose paper coated with cellulose hydrate can then optionally be formed into a tube whose overlapping edges are glued, sealed or sewn together to form a permanently firm seam. Tubular fiber-reinforced cellulose casings with or without a seam are widely used as artificial sausage casings.

In the prior art, various possibilities are disclosed, such as a

Nonwoven or fiber paper wet strength and alkali resistant can be made. According to US Pat. No. 3,135,613, a hemp fiber paper is impregnated with a dilute viscose solution, the viscose solution containing a proportion of cellulose xanthate corresponding to 0.5 to 3% by weight of cellulose. The Cellulose xanthogenate is then regenerated to cellulose hydrate in an acidic spin bath. The impregnated nonwoven fabric is then washed and dried. The regenerated cellulose coating on the hemp fibers is so thin that the porous structure of the paper is preserved. Above all, it increases the wet strength of the paper. A disadvantage of this so-called viscose-bound fiber paper is the fact that the coating of regenerated cellulose is not sufficiently alkali-resistant and resistant to hydrolysis. In the production of fiber-reinforced cellulose casings, the fiber paper is coated with viscose solution, which is known to be highly alkaline. The effect of the coating viscosity on the paper is already considered

Cellulose hydrate binder present for the paper fibers therefore partially dissolved again. The paper fibers are then no longer sufficiently firmly connected. This is also noticeable in the finished fiber-reinforced cellulose casings. They tend to burst even at a relatively low internal pressure.

In order to overcome this drawback, fiber papers have been developed which have otherwise been made wet-strength. For example, GB 1 091 105 discloses a hemp fiber paper containing an alkali-curing synthetic resin, for example, a polymeric reaction product of epichlorohydrin with polyamide or a polyethyleneimine resin. To produce a fiber-reinforced cellulose food casing, this paper is shaped into a tube in the known manner and coated with viscose. The cellulose is then regenerated as usual from the viscose.

In US-A 3484256 this concept is developed further. The fiber paper is now bonded with a mixture of a cationic thermosetting resin and an ionic or non-ionic polyacrylamide resin. However, the bursting strength of the fiber-reinforced cellulose hydrate sausage casings produced with this fibrous paper is still insufficient for certain sausage types.

The non-prepublished DE-A 10 2004 051 298 describes a wet-strength fiber fleece, preferably a fiber paper, which, in addition to fibers of cellulose-containing material, additionally contains fibers of thermoplastic material which are firmly welded together at the crossing points. The fibers of cellulose-containing material are preferably hemp fibers, while the fibers of thermoplastic material are preferably those of polypropylene, polyester or polyamide. The fibers are bonded under the action of pressure and / or heat, in particular with the aid of heated calender roll pairs, which is expensive in terms of apparatus. The nonwoven or fiber paper is used in particular as reinforcement in food casings based on regenerated cellulose, especially in artificial sausage casings based on cellulose hydrate.

It is therefore still the task to provide a fiber paper or nonwoven fabric available that has a high wet strength and this even after exposure to alkaline media, such as the viscose used for coating retains. It is said to be particularly suitable as fiber reinforcement in food casings based on cellulose hydrate. The covers made with it should be firm and elastic. They should also show sufficient swellability and good shrinkage behavior. The non-woven fabric should also be environmentally friendly and easy to produce. The cellulose fiber casings produced with the fibrous web to be developed should at the same time be strong and elastic, they should have a high swelling capacity and good shrinkage behavior.

The problem was solved with a non-woven fabric or paper which is bound with synthetic resin and with diluted viscose. The key improvement is that the cellulose hydrate is treated from the dilute viscose with a low molecular weight, especially a cyclic urea methylol. The cyclic urea methylol reacts with the cellulose and cross-links it to become more resistant to alkali.

The present invention accordingly provides a viscose-bonded and resin-bonded nonwoven fabric based on cellulosic fibers, characterized gekenn¬ characterized in that it is additionally crosslinked with a low molecular weight urea methylol. The term "low molecular weight urea methyls" should be understood as meaning compounds which contain not more than 3, preferably not more than 2, substituted urea groups of the structure -N (CH ₂ -OH) -CO-N (CH ₂ -OH) - or - NH-CO-N (CH ₂ -OH) ₂ contain and which do not react with each other, ie, which are stable as molecules and do not condense.

The low molecular weight urea-methylol preferably has a cyclic structure. Examples of such urea-methylols are optionally substituted in the 4- and / or 5-position substituted 1,3-bis-hydroxymethyl-tetrahydro-imidazol-2-one (= dimethylol-ethyleneurea), especially 4,5-dihydroxy-1,3 -bis-hydroxymethyl-tetrahydro-imidazol-2-one (= dimethylol-dihydroxy-ethyleneurea), a 1,3-bis-hydroxymethyl-5- (C 1 -C 6) -alkyl-tetrahydro-1H - [3 , 5] triazin-2-one, especially 1, 3-bis-hydroxymethyl-5-ethyl-tetrahydro-1 / 7- [1, 3,5] triazin-2-one (= dimethylol-ethyl-triazinone), 1 , 3-bis-hydroxymethyl-tetrahydro-1H-pyrimidin-2-one (= dimethylol propylene urea), 5-hydroxy-1,3-bis-hydroxymethyl-tetrahydro-1 / - / - pyrimidin-2-one (= dimethylol -hydroxy-propyleneurea), tetrakis-hydroxymethyl-tetrahydro-1H .SH-imidazo ^. δ-c / limidazole ^. d-dione (= tetramethylol-acetylenediurea). Such urea-methylols are known and described for example in DE-OS 22 46 829. The nonwoven fabric according to the invention contains about 1 to 12% by weight, preferably about 3 to 6% by weight, of cyclic ureamethylol (generally in crosslinking form), based on its dry weight.

Viscose bonding is generally accomplished by treating the fiber paper with a dilute viscose solution. The solution expediently contains about 1.0 to 3.0% by weight, preferably about 1.5 to 2.5% by weight, of cellulose in the form of cellulose xanthate.

Water-soluble cationic resins, in particular polyamine-polyamide-epichlorohydrin resins, are preferably used for the resin bond. However, other resins or glues can be used, such as urea-formaldehyde or urea-melamine-formaldehyde resins.

The resin or resin mixture can be mixed with the aqueous pulp (PuIp), from which then the fiber fleece is scooped. It can also be applied to an already existing fiber fleece. In either case, the paper is then dried by heating or heating. In the process, the resin and / or the glue crosslinks and in this way strengthens the fiber fleece. The fibers of cellulose-containing material are preferably hemp fibers. Instead of or in addition to the hemp fibers, it is also possible to use other vegetable cellulosic fibers or derived, in particular chemically modified, vegetable fibers.

In a particular embodiment, the cellulosic fibers are blended with fibers of synthetic polymers. Examples include fibers of polypropylene, polyamide or polyester. However, the proportion of these fibers should not be too high, otherwise the cellulose regenerated from the coating viscose will no longer sufficiently adhere to the fiber paper in the finished cellulose fiber gut. Suitably, a proportion of 1 to 20 wt .-%, preferably 2 to 12 wt .-%, based on the weight of the cellulosic fibers.

The nonwoven or paper of the present invention generally has a weight of about 12 to 30 g / m ² , preferably about 15 to 28 g / m ² . It shows, inter alia, a higher wet and dry strength than the previously used fiber papers in which the binding cellulose is not crosslinked. Above all, it shows a higher alkali resistance, which is of particular importance in the production of fibrous casings according to the viscose method.

The tubular food casings according to the invention may additionally be coated or impregnated inside and / or outside. Suitable coatings or impregnations are generally known to the person skilled in the art. Particularly noteworthy are PVDC inner coatings, which greatly reduce the permeability of the shell for water vapor and atmospheric oxygen. For the PVDC inner coating in particular vinylidene chloride copolymers are used which have about 60 to 85 wt .-% of VDC units. Furthermore, impregnations should be mentioned with which the adhesion of the casing to the food therein can be adjusted. Particular mention is made of the so-called easy-peel impregnations, which make the shell easy to peel. Finally, the food casing according to the invention may also be saturated with liquid smoke or other flavoring, flavoring and / or coloring agents. The production of the fibrous paper or nonwoven according to the invention is carried out by methods which are in principle familiar to a person working in the manufacture of fiber paper. It comprises in particular the following steps:

- preparing an aqueous slurry (PuIp) comprising fibers of cellulosic material; if appropriate, mixing the pulp with water-soluble binders, preferably with water-soluble cationic resins, in particular with polyamine-polyamide-epichlorohydrin resins; - depositing the fibers on a screen to form a fiber paper; Drying the fiber paper;

Treating the dry fiber paper with dilute viscose which additionally contains at least one cyclic urea methylol; Regenerating the viscose to cellulose hydrate in an acidic precipitation bath and - re-drying.

In a further embodiment of the process, the cyclic urea methylol is not mixed with the viscose, but contained in the subsequent acidic precipitation bath. In addition, the cyclic urea methylol may also be contained in a separate treatment bath. However, this embodiment is less preferred.

The preparation of the food casing according to the invention is carried out by methods which are known in principle to the person skilled in the art. In this case, the fiber paper bound to thermal and hydrolysis is generally cut into webs of suitable width, which are formed into tubes with overlapping longitudinal edges. The hoses are then exposed from the outside, from the inside or from both sides with viscose (external viscose, internal viscose or double viscose). In precipitation and wash baths, the cellulose is regenerated from the viscose. Alternatively, the tubes made of the fibrous paper according to the invention can also be coated with NMMO cellulose solutions from the outside, from the inside or from both sides. This procedure has the advantage that no acidic precipitation baths are needed. In order to be able to modify the properties of the food casings in accordance with the specifications of the users, it is possible the viscose or the NMMO-cellulose solution may be added polymeric additives such as alginic acid or alginates or polyvinylpyrrolidone. Preference is given to additives which permanently soften the food casing and are not washable, ie act as primary plasticizers. The shell may instead of or in addition to such primary plasticizers still secondary (= washable)

Plasticizers, such as glycerin included.

The cellulosic fiber casings according to the invention can be made up in a generally known manner; in particular, they can be compressed in sections into shirred caterpillars.

The food casing is particularly suitable as an artificial sausage casing, beispiels¬ example for raw sausage, such as salami.

The following examples serve to illustrate the invention. Percentages are to be understood as weight percentages unless stated otherwise or apparent from the context.

Example 1 Hemp fibers were converted by the usual method into a highly diluted aqueous paper pulp in which the hemp fibers had a proportion of 0.1 to 0.2%. To the fiber pulp was added a water-soluble polyamine-polyamide-epichlorohydrin resin. Its amount was such that the finished nonwoven fabric contained 2% of resin. The powder was then passed over a skewed screen, on which the fibers were then coarsely textured

Fiber paper formed. The fiber paper web was passed over heated rolls with a large diameter and dried. The paper had a weight of 21 g / m ² after drying. It was then passed through a runner which contained a mixture of dilute (1%) viscose and 5% dimethylol ethyleneurea (© Cassurit RI from Clariant Deutschland GmbH). To the

To regenerate cellulose from the viscose, the paper web was then passed through an acidic bath. Finally, the paper web was dried again and wound up. The proportion of regenerated cellulose was about 1, 5%, based on the dry weight of the paper. When wet, the paper showed a Tensile strength of 6 to 7 N / mm ² (average in the longitudinal and transverse directions) and an elongation at break of 7 to 8%, based on the initial length (mean in the longitudinal and transverse directions). After 10 minutes of treatment with a 6% NaOH aqueous solution, the paper had lost only 12 to 16% of its tear strength, while a fiber paper whose regenerated cellulose is not crosslinked generally loses about 24 to 26% in tear strength.

The fiber paper was then conventionally cut into sheets of appropriate width, which were then formed into tubes with overlapping longitudinal edges and coated with viscose from the outside. The fiber paper was from the

Viscose permeated perfectly. The cellulose was coagulated and regenerated in the usual way with precipitating and washing baths. It adhered well to the fiber paper and did not tear off under mechanical stress. The tube produced in this way of the caliber 75 had a weight of 85 g / m ² (% at 12 Residual moisture and 22% glycerin) showed a bursting pressure (wet) of 76.5 kPa, manufactured ie 12% higher than the with conventional fiber paper. The static elongation at 21 kPa was 82.5 mm (specification: 80.3 to 83.3 mm).

The casings could easily be gathered into caterpillars, which could then be filled with sausage meat just as easily on automatic filling machines. Due to the higher strength, the failure rate due to Platzer was significantly lower.

Example 2

Example 1 was repeated except that the resin-bonded fiber paper had a dry weight of 23.7 g / m ² . It also contained 2% polyamine-polyamide-epichlorohydrin resin. The dry paper was run through a blade containing a 1% viscose solution and then through another blade containing a 2% aqueous sulfuric acid. In the further runner, the cellulose was coagulated from the viscose and regenerated. The additional skid additionally contained 5%, based on the weight of the regenerated cellulose, of dimethylol-dihydroxy-ethyleneurea (ΘArkofix NG from Clariant Deutschland GmbH). The fiber paper was then dried again and wound up. When wet, it had a tenacity of 9 to 9.5 N / mm ² (average in the longitudinal and transverse directions) and an elongation at break of 6 to 6.5%. To When treated with alkali (6% aqueous NaOH, 10 minutes), the paper had lost only 8 to 12% of its wet strength. The elongation at break remained unchanged.

From the paper, a tube of caliber 90 was formed, which was then coated from the outside with viscose. After regeneration of the cellulose from the viscose in the usual spinning and washing baths, the fiber intestine had a weight of 88 g / m ² (at 10% residual moisture content and 22% glycerol content) and had a burst pressure of 75 kPa. This value was 22% above the target value of a wrapper made with conventional fiber paper. The static elongation at 21 kPa was 101 mm (specification: 99 to 102 mm). The covers were extremely stable. They could be gathered well and filled with sausage meat on automatic filling machines. The shrinkage, ripening and peeling behavior of the sheath was normal and corresponded to that of a conventional fibrous gut.

Example 3

In the manner described in Example 1, a fiber paper was prepared which had a dry weight of 25.4 g / m ² . As in Example 2, the fiber paper was first driven through a skid that contained a 1% viscose solution. It then passed through a further runner in which a mixture of 2.5% strength aqueous sulfuric acid and 3%, based on the weight of the cellulose in the viscose, of dimethylol-propyleneurea (© Fixapret PH BASF Aktiengesellschaft) was. The paper was dried again and then wound up. It had a tensile strength of 9 N / mm ² and an elongation at break of 7%. After alkali treatment (6% aqueous NaOH, 10 minutes), the paper had lost only 15% of its wet strength.

An externally viscose casing of caliber 120 with a weight of 104 g / m ² (at 10% residual moisture content and 22% glycerol content) produced with the paper had a burst pressure of 64 kPa, ie 18.5% above the usual standard value. The static elongation at 21 kPa was 135 mm (specification: 133 to 137 mm). The case could be processed easily. Example 4 (comparative example)

A hemp fiber paper with a weight of 17 g / m ² , which was regenerated from the viscose, as described in Example 1, with resin and viscose

However, cellulose not crosslinked with a urea methylol was formed into a 58 gauge tube with overlapping longitudinal edges. The hose was then coated with viscose from the outside with an annular nozzle. After this

Passing through the various spinning and washing baths, a conventional cellulose fibrous casing with a weight of 84 g / m ^{2 was} obtained therefrom, with a water content of 10%. The burst pressure (wet) of the fibrous gut was 80 kPa.

When wet, the paper exhibited a tear strength of 4.8 N / mm ² in the longitudinal direction and 5.9 N / mm ² in the transverse direction. After the alkali treatment, the paper had a tensile strength of 3.6 N / mm ² in the longitudinal direction and 4.6 N / mm ² in the transverse direction. The loss of tear strength was 24% in the longitudinal direction and 21% in the transverse direction.

Claims

claims

1. viscose and resin-bonded nonwoven fabric based on cellulosic fibers, characterized in that it is additionally crosslinked with a low molecular weight, not self-reacting urea methylol.

2. Nonwoven fabric according to claim 1, characterized in that the nieder¬ molecular urea methylol is cyclic.

3. Nonwoven fabric according to claim 2, characterized in that the cyclic urea methylol optionally substituted in 4- and / or 5-substituted position 1, 3-bis-hydroxymethyl-tetrahydro-imidazol-2-one (= dimethylol ethyleneurea), preferably 4,5-dihydroxy-1,3-bis-hydroxymethyl-tetrahydro-imidazol-2-one (= dimethylol-dihydroxy-ethyleneurea), a 1,3-bis-hydroxymethyl-5- (C 1 -C 6) -alkyl tetrahydro-1 H- [1,3,5] triazin-2-one, preferably 1,3-bis-hydroxymethyl-5-ethyl-tetrahydro-1 W- [1,3,5] triazin-2-one ( = Dimethylolethyl-triazinone), 1,3-bis-hydroxymethyl-tetrahydro-1H-pyrimidin-2-one (= dimethylol-propyleneurea), 5-hydroxy-1,3-bis-hydroxymethyl-tetrahydro-1 / - / - pyrimidin-2-one (= dimethylol-hydroxy-propyleneurea) or tetrakis-hydroxymethyl-tetrahydro-1 / - /, 3H-imidazo [4,5-c (limidazole-2,5-dione (= tetramethylol-acetylenediurea) is.

4. Nonwoven fabric according to one or more of claims 1 to 3, characterized in that the proportion of urea methylol 1 to 12 wt .-%, preferably 3 to 6 wt .-%, in each case based on its total dry weight.

5. Nonwoven according to one or more of claims 1 to 4, characterized in that the resin is a water-soluble cationic resin, preferably a polyamine-polyamide-epichlorohydrin resin.

6. Nonwoven fabric according to one or more of claims 1 to 5, characterized in that it has a dry weight of 12 to 30 g / m ² , preferably from 15 to 28 g / m ² .

7. A process for producing the nonwoven fabric according to one or more of claims 1 to 6, characterized in that it comprises the following steps:

a) preparing an aqueous slurry (PuIp) comprising fibers of cellulosic material; b) optionally mixing the pulp with water-soluble binders, preferably with water-soluble cationic resins, in particular with polyamine-polyamide-epichlorohydrin resins; c) depositing the fibers on a wire to form a fiber paper; d) drying the fiber paper; e) treating the dry fiber paper with dilute viscose, which additionally contains at least one low molecular weight, not self-reacting urea methylol; f) Regenerating the viscose to cellulose hydrate in an acidic

Precipitation bath and g) re-drying.

8. The method according to claim 7, characterized in that the urea methylmethylol is not mixed with the dilute viscose, but is contained in the acidic precipitation bath.

A food casing based on regenerated or precipitated cellulose, characterized in that it comprises a nonwoven according to claims 1 to 6 as a reinforcement.

10. food casing according to claim 9, characterized in that it is additionally coated or impregnated inside and / or outside.

11. Food casing according to claim 9, characterized in that it is an artificial sausage casing.