EP3028843A2 - Flame retardant corrugated board and method of manufacturing - Google Patents

Abstract

The invention relates to a method for producing flame-retardant corrugated board (10, 100) and corresponding flame-retardant corrugated board (10, 100). In the method, a corrugated web (14) is made from a first corrugated base paper web of flame retardant paper. Two flat corrugated base paper webs (12, 16) are adhered to this corrugated web (14), using starch added as an adhesive with a rheology modifier. The rheology modifier is designed such that a film resulting from adhesive application breaks faster than standard strength and / or the solids content of the adhesive is greater than standard strength.

Description

The invention relates to a method for producing flame-retardant corrugated cardboard, in which a corrugated web is produced from a first corrugated base paper web and a second and a third corrugated base paper web is glued to the corrugated web such that the corrugated web is arranged between the flat corrugated paper webs. Furthermore, the invention relates to a flame-retardant corrugated cardboard from a flat inner web, a flat outer web and a arranged between the inner web and the outer web and a web of flame retardant corrugated cardboard from an inner web, an outer web, an intermediate web and two wave paths between the inner web and the intermediate web and are arranged between the intermediate web and the outer web.

As standard, corrugated board is produced in several steps from so-called corrugated base paper. Here, the corrugated base paper is heated and moistened to achieve the necessary elasticity and receptivity for the gluing of the paper. In order to produce the corrugated web, in the further production process the corrugated base board paper web is passed under pressure and heat input between two gearwheel-like corrugating rollers engaging each other, whereby the initially flat corrugated board base paper web receives its wave form. The corrugated web is then glued to flat corrugated base paper webs, this gluing being done by default with a starch based adhesive under heat. In a single-wall corrugated board, a corrugated web is used, to which two flat corrugated base paper webs, the inner web and the outer web, are glued on opposite sides.

In two-shaft corrugated cardboard, three flat corrugated base paper webs, the inner web, the intermediate web and the outer web, and two wave paths are used, the wave paths between the inner web and the intermediate web and between the intermediate web and the outer web are arranged.

In this standard manufacturing process, relatively large amounts of moisture are introduced into the corrugated base paper webs with the glue. Moreover, in the standard manufacturing process, a high temperature is necessary to achieve the desired shape and strength.

Both the high moisture input and the high temperature have the consequence that water-soluble impregnations of the corrugated base paper webs are damaged or completely lost in the production process.

It is an object of the invention to provide a method for producing corrugated cardboard and such a corrugated board, wherein the corrugated board has flame retardant properties.

The aim is in particular to produce a flame-retardant high-quality corrugated board, which has the flame retardant properties according to DIN 4102 building material class B1 even after the manufacturing process / process and in which also the products made therefrom, in the field of packaging, displays, elements for Stand construction, printed corrugated cardboard have the corresponding flame-retardant properties according to DIN 4102 building material class B1.

This object is achieved by a method having the features of claim 1 and by corrugated cardboard having the features of the independent apparatus claims. Advantageous developments of the invention are specified in the dependent claims.

According to the invention, first a wave web is produced from a first corrugated base paper web of flame-retardant paper. This can be done in particular by the usual methods. Subsequently, a flat second corrugated base paper web of flame-retardant paper is glued to the shaft path. Further, a flat third corrugated base paper web of flame-retardant paper is bonded to the corrugated web so that the corrugated web is disposed between the second and third corrugated green paper webs. The adhesive used is a starch added with a rheology modifier, wherein the rheology modifier is designed in such a way that a film formed during adhesive application breaks more rapidly than pure starch and / or the solids content of the adhesive is greater than pure starch.

By using only flame-retardant paper as corrugated base paper webs is achieved that also the resulting corrugated board itself has the same flame retardant properties. The use of a starch added with the rheology modifier allows less moisture to be introduced into the corrugated base paper webs in the manufacturing process, and overall, to drive the corrugated board making machine at a lower temperature. Both have the consequence that water-soluble impregnations, over the standard flame retardant paper, these flame retardant properties can not be damaged during the manufacturing process. If one were to use a starch without a rheology modifier, the moisture input would be so strong that the flame retardant impregnation would at least partially dissolve and thus the corrugated board would not have the flame retardant properties.

In particular, this modified thickness ensures that the film produced during the application of the adhesive breaks off more rapidly between the applicator roll, with which the application of the adhesive is carried out, and the wave path. Thus, the size of the glue application can be minimized, which in turn reduces the moisture content introduced into the corrugated web and bonded flat corrugated base paper web.

In addition, the rheology modifier allows the adhesive to have a higher solids content, thereby decreasing the gelling point of the adhesive, which in turn results in less heating during production, thus minimizing heat input.

In particular, the standard corrugated board production plant for the corrugated board can be operated at a gentler level. In particular, the vapor pressure and / or the steam supply of the corrugated cardboard production plant can be reduced and / or the heating section can be operated at a lower temperature or the contact areas over which the corrugated base paper webs are passed over and wrapped around such heating sections can be minimized.

As a result, the flame retardant properties of the corrugated base paper used are retained.

The rheology modifier comprises in particular at least one tannin and / or at least one carbohydrate. In particular, this carbohydrate is not starch. Preferably, a chemically altered tannin and / or a chemically altered carbohydrate is used.

Furthermore, the rheology modifier may in particular comprise a biopolymer.

In particular, Cargill C * Rhem ™ from Cargill is used as a rheology modifier. In particular, the adhesive used is a special starch with this rheology modifier named Cargill C * GUM 037C5.

In a preferred embodiment, another corrugated web may be made from a fourth corrugated base paper web of flame retardant paper, this further corrugated web being adhered to the third corrugated base paper web. Furthermore, a flat fifth corrugated base paper web of flame-retardant paper is glued onto the further wave path in such a way that the further corrugated web is arranged between the third and the fifth corrugated paper web. In this case, the adhesive used is again starch mixed with the rheology modifier. In this way, a two-wave corrugated board is achieved, which has flame retardant properties.

As a corrugated base paper web, in particular flame-retardant paper with a flame-retardant impregnation, preferably a water-soluble flame-retardant impregnation, is used. About such impregnations can be achieved in a simple manner reliably the desired flame retardant property. In a particularly preferred embodiment, flame-retardant paper according to DIN 4102 building material class B1 is used as the corrugated base paper. hereby it is achieved that the corrugated board produced also meets the standards according to DIN 4102 building material class B1.

During the manufacturing process, at least a portion of the corrugated base paper webs are moistened and / or heated. The use of the rheology modifier ensures that the flame-retardant properties of the corrugated base paper are nevertheless retained. The moistening is carried out in particular by steaming with water vapor.

The heating preferably takes place via at least one heating unit, wherein in a first region of the heating unit a vapor pressure between 2.5 and 3.5 bar, in a second range between 1.0 and 2.0 bar and / or in a third range between 0 , 1 and 0.5 bar is used. If one were to use pure starch as an adhesive, as is standard in corrugated board production, a vapor pressure between 6 and 7 bar would be necessary in the first region, between 3 and 4 bar in the second region and between 1 and 2 bar in the third region. The modified starch thus significantly reduces the vapor pressure and thus the moisture introduced.

The production of the corrugated cardboard web from the first flat corrugated base paper web is effected in particular by passing this first corrugated paper web between two corrugating rolls under pressure and / or heat.

A further aspect of the invention relates to a flame-retardant corrugated board which comprises a flat inner web, a flat outer web and a corrugated web arranged between the inner web and the outer web, wherein the inner web, the outer web and the corrugated web are each made of a flame-retardant corrugated base paper are. This ensures that even the resulting single-wall corrugated board is itself flame retardant.

The inner web and the outer web are adhesively bonded to the corrugated web in particular, wherein the adhesive comprises starch added with a rheology modifier, wherein this rheology modifier is designed so that a film resulting from adhesive application breaks more rapidly than pure starch and / or the solids content of the adhesive is greater than pure starch. By means of this modified adhesive it is achieved that the introduction of moisture into the corrugated base paper and / or the necessary temperature are reduced, so that the flame-retardant properties of the corrugated base paper are not lost during the production of the corrugated cardboard.

In one preferred embodiment, the inner web, the outer web and the corrugated web each consist of flame-retardant base paper according to DIN 4102 building material class B1, so that the resulting single-wall corrugated cardboard fulfills these standards as well.

A further aspect of the invention relates to a flame-retardant corrugated board which comprises a flat inner web, a flat intermediate web, a flat outer web and a first wave web arranged between the inner web and the intermediate web and a second wave web arranged between the intermediate web and the outer web. The inner web, the intermediate web, the outer web and the first and the second wave web are each made of a flame-retardant corrugated base paper, so that the resulting two-wave corrugated board has flame-retardant properties.

The inner web, the intermediate web and the outer web are adhesively bonded to the respective wave web, in particular with the aid of an adhesive, wherein the adhesive comprises starch added with a rheology modifier. The rheology modifier is designed in such a way that a film produced during adhesive application breaks more rapidly than pure starch and / or the solids content of the adhesive is greater than pure starch. This ensures that by minimizing the moisture input and the necessary temperature, the flame retardant properties of the corrugated base paper web, in particular an impregnation, also remain during the manufacturing process.

The inner web, the intermediate web, the outer web and the first and the second wave paths are preferably each made of a flame retardant corrugated base paper according to DIN 4102 building material class B1, so that the resulting two-wave corrugated meets the standards of this DIN.

In further embodiments, more than two-wave flame-retardant corrugated cardboard can be produced, in each of which further wave webs and other flat corrugated base paper webs are adhered, which also in this case preferably each used as an adhesive with this rheology modifier strength is used.

Further features and advantages of the invention will become apparent from the following description, which illustrates the invention with reference to embodiments in conjunction with the accompanying figures.

Fig.1

eine schematische Darstellung einer einwelligen Wellpappe;

Fig.2

eine schematische Darstellung einer zweiwelligen Wellpappe;

Fig.3

ein Diagramm der Stapelfeuchte bei der Verwendung von modifizierter Stärke und der Verwendung von Standardstärke; und

Fig.4

ein Diagramm des Dampfdruckes einer Heizeinheit einer Wellpappenherstellungsanlage bei der Verwendung von Standardstärke und der Verwendung von modifizierter Stärke.

Show it:

Fig.1

a schematic representation of a single-wall corrugated cardboard;

Fig.2

a schematic representation of a two-wave corrugated cardboard;

Figure 3

a chart of stack moisture using modified starch and standard strength; and

Figure 4

a graph of the vapor pressure of a heating unit of a corrugated board manufacturing plant using standard strength and the use of modified starch.

In Fig.1 the schematic representation of a single-wall corrugated cardboard 10 is shown. The corrugated cardboard 10 comprises a flat inner web 12 and a likewise flat outer web 16, between which a wave path 14 is arranged. The common names in practice "inner track" and "outer track" are arbitrary, ie that the outer web can be arranged inside when using and vice versa.

In the manufacture of the flame-retardant single-walled corrugated cardboard 10, flame-retardant corrugated base paper is used both for the inner web 12, the corrugated web 14 and for the outer web 16. In particular, a corrugated base paper is used, which has an impregnation, through which the corrugated base paper meets the requirements of DIN 4102 class B1.

In the production of the single-walled flame-retardant corrugated cardboard 10, a first corrugated base paper web 14 is first heated and moistened in order to achieve the necessary elasticity and receptivity for the subsequent bonding of the web. The first corrugated base paper web 14 is passed under pressure and the action of heat between two corrugated rollers meshing like a gear wheel that from the previously flat first corrugated base paper web, the wave path 14 is formed. Subsequently, the flat corrugated base paper webs 12 and 16 are glued to the wave path 14 by means of an adhesive as inner and outer web under the action of heat.

As the adhesive, starch added with a rheology modifier is used. The rheology modifier allows the application of the adhesive to be applied to the corrugated web 14 thinner than when using standard strength, so that less adhesive has to be applied overall. This has the consequence that less moisture is introduced into the webs 12 to 16.

In addition, the rheology modifier serves to have a lower gelling point compared to the standard thickness commonly used to make corrugated board, so that less heat is required during manufacture.

Both serve to ensure that the plant with which the corrugated board 10 is produced can be operated in a very gentle manner. In particular, the steam pressure or the steam supply can be reduced and a heating unit can be operated at a lower temperature or the angle of wrap of the webs around the heating unit can be reduced. Overall, it is achieved by the lower moisture input and the lower temperature that the impregnation over which the flame retardant properties of the corrugated base paper are achieved in the production of corrugated cardboard 10 is not lost. Thus, the single-walled corrugated board 10 has the appropriate flame-retardant properties and meets the requirements of DIN 4102 building material class B1.

In Fig.2 a schematic representation of a flame retardant double corrugated paperboard 100 is shown. The corrugated cardboard 100 has an inner web 112, an intermediate web 116 and an outer web 120, wherein between the inner web 112 and the intermediate web 116, a first wave path 114 and between the intermediate web 116 and the outer web 120, a second wave path 118 are arranged. All five webs 112 to 120 are made of a flame-retardant corrugated base paper, so that the two-wave corrugated cardboard 100 has the corresponding flame-retardant properties. As a strength, in turn, in this case, in particular, a starch mixed with a corresponding rheology modifier is used.

The rheology modifier used in all embodiments in particular Cargill C * Rhem ™ Cargill.

In Figure 3 a diagram is shown in which two series of measurements of the humidity of the corrugated cardboard are shown after the production. The line indicated by the reference numeral 30 here represents the humidity in the use of standard strength and the line 32 the humidity in the use of modified starch, that is, of starch to which the rheology modifier is added Figure 3 can be removed, the use of modified starch as an adhesive, the moisture is reduced from about 95% to only 70%.

Figure 4 shows a diagram of the vapor pressure of a heating unit of corrugated board manufacturing plant, over which the corrugated base paper is heated and moistened. Again, line 40 shows the necessary vapor pressure when using standard thickness, line 42 the necessary vapor pressure when using the modified starch. Here, the heating unit is divided into three areas in which it is operated with different vapor pressure. Also here again shows that the vapor pressure in the modified starch is much lower than the standard thickness.

LIST OF REFERENCE NUMBERS

10, 100

corrugated cardboard

12, 16, 112, 116, 120

flat corrugated base paper web

14, 114, 118

moguls

30, 32, 40, 42

line

Claims (15)

Method for producing flame-retardant corrugated board,
wherein a corrugated web (14, 114) is made from a first corrugated base paper web of flame retardant paper,
a flat second corrugated base paper web (12, 112) of flame-retardant paper is adhered to the corrugated web (14, 114), and
wherein a flat third corrugated base paper web (16, 116) of flame retardant paper is bonded to the corrugated web (14, 114) such that the corrugated web (14, 114) is interposed between the second and third corrugated green paper webs (12, 112, 16, 116) is
wherein starch added as an adhesive with a rheology modifier is used, wherein the rheology modifier is designed such that a film resulting from adhesive application breaks faster than standard strength and / or the solids content of the adhesive is greater than standard strength. A method according to claim 1, characterized in that the rheology modifier comprises at least one tannin and / or at least one carbohydrate. A method according to claim 2, characterized in that a further wave path (118) is made of a fourth corrugated base paper web of flame-retardant paper, that this further wave path (118) is glued to the third corrugated base paper web (16, 116), that on the other A corrugated web (118) is adhered to a planar fifth corrugated base paper web (120) of flame retardant paper such that the further corrugated web (118) is interposed between the third and fifth corrugated base paper webs (120) using the same adhesive as for adhering the second corrugated green paper web (120). 12, 112) is used. Method according to one of the preceding claims, characterized in that is used as a corrugated base paper web (12, 14, 16, 112 to 120) flame-retardant paper with a flame-retardant impregnation, in particular a water-soluble flame-retardant impregnation. Method according to one of the preceding claims, characterized in that is used as corrugated base paper (12, 14, 16, 112 to 120) flame-retardant paper according to DIN 4102 building material class B1. Method according to one of the preceding claims, characterized in that at least part of the corrugated base paper webs (12, 14, 16, 112 to 120) is moistened and / or heated. A method according to claim 6, characterized in that the moistening takes place via a steaming with water vapor. A method according to claim 6 or 7, characterized in that the heating takes place via at least one heating unit, and that in a first region of the heating unit, a vapor pressure between 2.5 and 3.5 bar, in a second range between 1.0 and 2, 0 bar and / or in a third range between 0.1 and 0.5 bar is used. Method according to one of the preceding claims, characterized in that the first corrugated base paper web (14, 114) is guided for corrugation under pressure and / or heat between two corrugating rolls. Flame retardant corrugated board (10),
with a flat inner track (12),
a flat outer track (16), and
with a wave path (14) arranged between the inner web (12) and the outer web (16),
wherein the inner web (12), the outer web (16) and the wave path (14) are each made of a flame-retardant corrugated base paper. A flame retardant corrugated board (10) according to claim 10, characterized in that the inner web (12) and the outer web (16) with the aid of an adhesive to the corrugated web (14) are glued, wherein the adhesive comprises mixed with a rheology modifier starch, and wherein the Rheology modifier is designed such that a resulting film during adhesive tears faster than standard strength and / or the solids content of the adhesive is greater than standard strength. Flame retardant corrugated cardboard (10) according to claim 10 or 11, characterized in that the inner web (12), the outer web (16) and the wave path (14) each consist of a flame-retardant corrugated base paper according to DIN 4102 building material class B1. Flame retardant corrugated board (100),
with a flat inner track (112),
a flat intermediate track (116),
a flat outer track (120),
a first wave path (114) arranged between the inner web (112) and the intermediate web (116), and
with a second wave path (118) arranged between the intermediate track (116) and the outer track (120),
wherein the inner web (112), the intermediate web (116), the outer web (120) and the first and second wave webs (114, 118) are each made of a flame-retardant corrugated base paper. Flame-retardant corrugated cardboard (100) according to claim 13, characterized in that the inner web (112), the intermediate web (116) and the outer web (120) by means of an adhesive to the respective wave path (114, 118) are glued, wherein the adhesive with starch added to a rheology modifier, and wherein the rheology modifier is designed so that a film resulting from adhesive application breaks faster than standard thickness and / or the solids content of the adhesive is greater than standard strength. A flame retardant corrugated board (100) according to claim 13 or 14, characterized in that the inner web (112), the intermediate web (116), the outer web (120) and the first and second wave path (114, 118) each consisting of a flame retardant corrugated board according to DIN 4102 building material class B1 exist.

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