The present invention relates to the field of paper making, and in particular to a method for producing paper which is disaggregatable in water-based liquids, and to a continuous machine for the continuous production of the paper in reels.

Background of the invention

The paper industry exhibits a high degree of diversity in the types of installation used for the continuous production of the various types of paper available on the market. In the paper industry, the term "paper" denotes a felt of vegetable fibres, the main components of which are cellulose or cellulose and lignin, produced from a suspension of these fibres in water. The conversion from suspension to felt is carried out by drainage on a forming fabric or on a forming roll. The resulting thin web has measurements in the two dimensions of width and length which are greater by many orders of magnitude than the third dimension of thickness.

For the purposes of the present invention, "paper" denotes a product containing at least 50% cellulose or cellulose and lignin.

A paper production installation usually includes an area for forming the paper web, an area for drying by drainage and mechanical dewatering, an area for drying by evaporation, and a winding system. Each of these areas can be produced by using more than one technological solution; for example, the first area, for forming the web, can be produced using either the forming roll (cylinder mould) technology or the flat table technology.

Dewatering, or drying, is an important operation in the manufacture of the paper web, and its control is one of the decisive factors for the final characteristics of the web.

Drainage and mechanical dewatering are the preferred mechanisms for water removal, because they are simpler and more convenient in terms of energy. Typically, the drainage and mechanical dewatering result in a 50% dry consistency, after which the drying step continues by evaporation of the remaining water.

In the course of drainage and mechanical dewatering, the substances dissolved in the water are lost together with the water itself, whereas the dispersed substances such as cellulose fibres may be retained by the forming fabric, depending on their dimensions. In evaporation, it is usually only the water that is lost.

Some patents relating to tissue paper describe how, in order to increase the thickness and softness of the paper, the evaporation drying step is performed sooner, reducing the amount of drainage and mechanical dewatering. The prior art includes various technical solutions for carrying out drying.

US5070626 describes an oven heated by infrared lamps, into which is directed a flow of air parallel to the paper surface.

US41 12587 proposes to dry the wet web to 60-70%, after which, following disaggregation, the web is formed and is subsequently dried with hot air to 90%. However, the first part of the method requires the forming of a paper web in a conventional way with a dry content of 40% to 50%, the water being removed by mechanical dewatering, by making the web pass through press rolls.

US3945881 describes a steam box mounted on the continuous machine fabric: the aim is to increase the pulp temperature, providing benefits in terms of ease of drying and uniformity of the wet transverse profiles of the web.

US20130228300 describes a system for impregnating, with an aqueous solution of urea, and continuously drying a paper web.

EP1725710 describes a device for conditioning (cleaning) the fabric of a continuous machine.

EP0988419B1 relates to a particular web for drying by the passage of air. The aim is to compete with the TAD ((through-air drying) system which is widely used in tissue machines. The main aim is to obtain soft, fluffy paper.

EP0907797B1 illustrates a machine for producing soft tissue paper. The paper web is drained to a consistency (dry content) of 20% to 30%, before being dried and transferred to other fabrics running at a lower speed than the forming fabric.

EP2643648 describes a system for impregnating and continuously drying a paper web, using a hot-air flotation oven.

In CA2568996 the paper web, having a consistency of 10% to 30%, is first transferred from the forming fabric to a textile fabric running at a lower speed than the forming fabric. On the second fabric, drainage and mechanical dewatering takes place until the paper web is brought to a dry content of 60%. This step of drying on the second fabric takes place by means of two non-thermal technologies, and therefore not by evaporation. The paper web is then transferred to a creping fabric. AU692127 describes a device for producing tissue paper with high bulk (low density). The paper web being formed is first brought to a consistency of at least 30% by conventional drainage and mechanical dewatering methods. The paper web being formed is then transferred, with crushing, to a coarse fabric. The transfer can be carried out by different technologies (pneumatic or mechanical) and causes an increase in thickness and bulk and a partial breakage of the links between the fibres of the paper web being formed. This effect is known as wet-straining. The web being formed is then transferred to a fabric for drying by the passage of hot air (through drying cylinder) and, if necessary, a Yankee cylinder, to produce a crepe paper.

US2000/088577 describes a method for producing absorbent webs.

US4440597 describes an installation for making high-bulk, MD-extensible tissue paper.

Disaggregatable paper, such as that described in WO2013/124804, is characterized by the presence of a suitable disaggregating agent in a quantity of between 3% and 30% by weight. This quantity of disaggregating agent can be used only by adding it to the initial suspension for making the paper.

For the purposes of the present invention, the term "paper" denotes a felt of virgin and/or recycled vegetable fibres of any origin (for example, wood pulp, mechanical pulp, semi- chemical pulp, chemical pulp, cotton lint, annual plants, etc.), the main components of which are cellulose or cellulose and lignin, present in a minimum content of 50% by weight, produced from a suspension of these fibres in water.

In the context of the present invention, the term "soluble paper" denotes a paper which is disaggregated, being dissociated into individual fibres, in contact with an aqueous liquid such as water, water-alcohol mixture, or water mixed with another solvent. In the present invention, "soluble" paper is also referred to by the term "disaggregatable", indicating complete disaggregation with slight manual agitation, without the aid of mechanical means. The user perceives this disaggregation as "soluble".

In the context of the present invention, soluble paper produced by the method described herein is suitable for many uses. It may be used as it stands, or may contain other components, such as perfumes, dyes, bactericides, medicines or cosmetics.

In the context of the present invention, the term "paper soap" denotes a paper impregnated with detergents.

The disaggregating agent is in itself soluble or highly soluble in water, and therefore, in the first step of forming the web, where the loss of water conventionally takes place by drainage or mechanical dewatering, there is a large-scale loss of the agent.

The problem therefore arises of providing a method and a corresponding machine for the manufacture of disaggregatable paper, also called soluble paper, which enables the requisite amount of disaggregating agent to be retained in the web during forming, possibly by varying the grammage and the speed of the machine.

Additionally, given the characteristics of the paper web which is disaggregatable in aqueous liquids, the subjecting of the web being formed to an open draw is critical for the avoidance of breaks in the web.

BRIEF DESCRIPTION OF THE INVENTION

It has now been discovered that a suitable combination of drainage, mechanical dewatering and evaporation mechanisms, together with control of the dry matter content during the production process, enables the aforesaid problems to be overcome, particularly the problem of controlling and regulating the loss of disaggregating agent during the step of forming the web, while maintaining the desired production levels.

The drainage, mechanical dewatering and evaporation can be carried out using any available technology, for example suction boxes, suction presses, heated rolls, hot-air ovens, infrared ovens, or microwave ovens. One object of the present invention is therefore a method for producing paper which is disaggregatable in aqueous liquids, as described in Claim 1 and the claims dependent thereon.

Another object of the present invention is a continuous machine for the execution of this method, as described in the corresponding independent claim and its dependent claims. One object of the present invention is a method for producing disaggregatable paper, particularly as described in WO2013/124804, the method comprising the following steps: a. forming the paper web; b. drying the paper web, the drying being carried out by drainage, mechanical dewatering and/or evaporation, using, for example, suction boxes, suction presses, hot-air ovens, infrared ovens or microwave ovens, to a dry content of about 30%, and the subsequent drying being carried out by evaporation, using, for example, heated rolls, hot-air ovens, infrared ovens, or microwave ovens; c. winding the web into a reel, wherein the web being formed must not be subjected to an open draw until it has reached aconsistency of more than about 30% dry.

In an embodiment of the present invention, the method comprises a further step b') of surface treatment, for example impregnation with detergents, before step c). In a preferred embodiment of step b), the first drying by drainage, mechanical dewatering and/or evaporation is carried out to a consistency of about 25% dry.

In another embodiment of the invention, the web being formed must not be subjected to an open draw until it has reached a consistency in the range from about 30% to about 50% dry. Another object of the present invention is an installation, also referred to herein as a continuous machine, for producing disaggregatable paper, particularly of the type described in WO2013/124804, the machine comprising: a) a forming section; b) a section for drying by drainage, mechanical dewatering and/or evaporation; c) a controlled air blowing system if required; d) a further section for drying by evaporation, preferably thermal; e) a winding section; wherein, in section b), the drying is carried out until the sheet has reached a dry percentage of about 30%; and wherein, in this machine, the first open draw is provided when the paper has reached a consistency of more than about 30% dry.

In one embodiment of the present invention, the machine provides a section for surface treatment, particularly spraying, for example with detergents, perfumes, dyes, bactericides, or any other component compatible with the disaggregatable paper substrate, placed between section d) and section e). In this case, a drying section may also be provided. The impregnation of the paper may be carried out by any available technology, for example inkjet, rotogravure, flexography, spray or size press technology.

In an exemplary embodiment of the present invention, section b) of the machine, for drying by drainage and mechanical dewatering, uses any available technology, for example foils, vacuum foils, or suction boxes. In an exemplary embodiment of the present invention, section b) of the machine, for evaporation drying, uses any available technology, for example hot-air ovens, infrared ovens or microwave ovens.

In the machine of the present invention, where provided, the first open draw is located at a point of the web path where the web has reached a consistency of more than about 30% dry. In another embodiment of the invention, in the machine the first open draw is provided when the web has reached a consistency in the range from about 30% to about 50% dry.

In one embodiment of the present invention, in the machine, section a) is separate from section b), and sections a) and b) are connected without any open draws. In one embodiment of the present invention, section d) of the machine for further (or second) dewatering preferably uses conventional thermal drying means.

In one embodiment of the present invention, an air blowing system is provided in section b) of the machine, and is placed under the web forming fabric. This system may be placed at the position of the evaporation drying system and may also extend beyond that system. The blowing system may also be placed only after the evaporation drying system.

One embodiment of the present invention provides the machine (1), wherein a pulp feed system (2), at a temperature in the range from about 10°C to about 80°C, supplies a closed- loop draining forming fabric (9) which carries the web being formed to the drying section composed of mechanical dewatering means (3) and thermal evaporation means (4, 5); and wherein a controlled air blowing system (6) is placed under the draining fabric (9) at the position of the thermal evaporation means (5); after the blowing system (6) and the means (5), the paper web being formed is transferred to a drying fabric (10) and is dried by evaporation by the means (7), which is followed by a winding system (8). In an alternative embodiment of the machine (1), wherein the evaporation drying means (7) is a heating roll system (28a) or a flotation oven (7a).

One embodiment of the present invention provides the machine (31), wherein the forming system (32) is separate from the drying section b) (34a, 34b, 35, 36). In a particular embodiment of the machine (31), a first step of drainage and mechanical dewatering (27) is carried out on the felt (33). One embodiment of the present invention provides the machine (41), wherein the drying section b) (44a, 44b, A) does not include the blowing system, and the further dewatering section d) (B) is composed of a series of heated rolls (45, 46).

The present invention will now be described in greater detail, with the additional use of examples and drawings. In the drawings,

Figure 1 shows a schematic representation of the continuous machine according to the present invention, with the basic sections (A) for forming, drying by drainage, mechanical dewatering and evaporation, and (B) a further section for evaporation drying, and a winding section.

Figure 2 and Figure 2A show a schematic exemplary representation of the continuous machine according to the present invention, where A and B refer to the sections of Figure 1. Figure 3 shows a schematic exemplary representation of a variant of the basic version of the continuous machine according to the present invention, where A and B refer to the sections of Figure 1. Figure 3 shows one of the possible arrangements of section A of Figure 1 , where the section for drying by drainage, mechanical dewatering and evaporation is essentially composed of a draining fabric (38), means for drying by mechanical dewatering (22), (24) and by evaporation (23), (25), placed alternately; the spraying device (29) is also shown.

Figure 4 shows a further variation of section A of Figure 1 , where the forming system (32) is completely separate from the first step of drying.

Figure 5 shows a further variation of Figure 1 , where the drying section A, again comprising means for drying by drainage, mechanical dewatering and evaporation, does not provide the blowing system, and section (B) is composed of a series of heated rolls (45, 46). The possible system for surface treatment, by spraying (50) for example, with a drying section (47, 48), is also shown in the installation (41).

DETAILED DESCRIPTION OF THE INVENTION Definitions

For the purposes of the present invention, a continuous machine is defined as a machine which can produce reels of paper in a continuous manner.

For the purposes of the present invention, the term "paper" denotes a felt of virgin and/or recycled vegetable fibres of any origin (for example, wood pulp, mechanical pulp, semi- chemical pulp, chemical pulp, cotton lint, annual plants, etc.), the main components of which are cellulose or cellulose and lignin, produced from a suspension of these fibres in water.

In the context of the present invention, the term "soluble paper" denotes a paper which is disaggregated, being dissociated into individual fibres, in contact with an aqueous liquid such as water, water-alcohol mixture, or water mixed with another solvent. In the present invention, "soluble" paper is also referred to by the term "disaggregatable", indicating complete disaggregation with slight manual agitation, without the aid of mechanical means. The user perceives this disaggregation as "soluble". In the context of the present invention, the term "about" denotes a neighbourhood of the stated value within which the invention can be used.

In the context of the present invention, "drainage" denotes a physical drying process, and "mechanical dewatering" denotes a drying process in which mechanical means, for example vacuum pumps or presses, are used. In the course of drainage and mechanical dewatering, the substances dissolved in the water are lost together with the water itself, whereas the dispersed substances such as cellulose fibres may be retained by the forming fabric, depending on their dimensions. In evaporation, it is usually only the water that is lost.

One object of the present invention is to provide a method for manufacturing disaggregatable paper, comprising the following steps: a) forming the paper web; b) drying the paper web, the drying by drainage, mechanical dewatering and/or evaporation being carried out to a dry content of about 30%, and the subsequent dewatering being carried out by evaporation; and c) winding the web into a reel, wherein the web being formed must not be subjected to an open draw until it has reached a consistency of more than about 30%.

Another object of the present invention is a continuous machine for producing soluble paper according to the aforementioned method. The installation and the continuous machine are designed for the production of disaggregatable paper, as described in WO2013/124804 for example, which may subsequently be impregnated with suitable detergents to provide a dry soluble paper soap.

Using the typical terminology of the paper industry, the continuous machine according to the present invention comprises four basic parts, as shown in Figure 1 : a) a forming section; b) a section for drying by drainage, mechanical dewatering and/or evaporation; c) a controlled air blowing system if required (not shown in Figure 1); c) a further section for drying by evaporation; and e) a winding section; wherein, in section b), the drainage and mechanical dewatering and/or evaporation means are arranged in such a way that the drying step is carried out with these means until the sheet has reached a dry percentage of about 30%; and wherein, in this machine, the first open draw is provided when the paper has reached a consistency of more than about 30% dry.

These four steps are also present in the standard paper production method, which essentially consists in a passage from a pulp of fibres, additives and water to a uniform sheet (with a consistency of about 0.1 % to 1.5%, preferably about 0.5% to 1.5%) and finally to a dry web with a residual presence of water of about 3% to 10%. In one embodiment of the present invention, the disaggregatable paper is as described in WO2013/124804, where the percentage amount of the disaggregating agent present in the finished web (10% to 20% or more) depends on the desired degree of disaggregation. A preferred disaggregating agent is carboxymethyl cellulose sodium salt.

According to the papermaking standard, the percentage of carboxymethyl cellulose (CMC) sodium salt is minimal (less than 0.5%).

It is impossible to obtain values of CMC as a disaggregating agent in the web described in WO2013/124804 by using the standard chemical-physical retention processes normally present in papermaking processes.

In the method and installation according to the present invention, the section for drying to about 30% dry again comprises a first step and corresponding means for drying by drainage, followed by a step and corresponding means of drying by mechanical dewatering, which may be followed by a step and corresponding means of drying by evaporation; alternatively, the step and corresponding means of drying by mechanical dewatering may be replaced by the step and corresponding means of drying by evaporation. These values of disaggregating agent can be achieved only by adding the exact amount of CMC to the pulp and maintaining it in the process water, by reducing drainage and mechanical dewatering of the web to a minimum, and operating by evaporation, which, by causing the water to evaporate, does not drain CMC from the environment of the web. This mode of operation is not typical of standard paper technology, which tends to make the greatest possible use of drainage and mechanical dewatering, for reasons of cost and productivity, while reducing thermal dewatering (evaporation) to a minimum. The degree of disaggregation of the paper is therefore obtained by controlling the concentration of disaggregating agent in the pulp and the percentage of drying by drainage and mechanical dewatering. For example, in order to obtain a good degree of disaggregation of the paper, with concentrations of 6% by weight of disaggregating agent in the pulp, the drying by drainage and mechanical dewatering of the paper web being formed must not exceed 25% dry, the process of drying by evaporation only ending with a content of about 20% by weight of disaggregating agent. The same degree of disaggregation may be obtained by starting with a lower concentration of disaggregating agent (4% by weight), but with a dry level of 17% after drying by drainage and dewatering, with a content of about 20% by weight of disaggregating agent. If the dry level after drying by drainage and dewatering is 17%, but the concentration of disaggregating agent in the pulp is 6% by weight, a paper with the maximum disaggregation is obtained, with a content of about 30% by weight of disaggregating agent. If the dry level after drying by drainage and dewatering is 17% while the concentration of disaggregating agent in the pulp is 2% by weight, a paper with an imperfect degree of disaggregation is obtained, with a content of about 9% by weight of disaggregating agent. Thus, for a given concentration of disaggregating agent in the pulp, the disaggregation of the paper, which is proportional to the amount of disaggregating agent present, will increase with a decrease in the percentage of drying due to drainage and mechanical dewatering; the same effect will be achieved if the concentration of disaggregating agent in the pulp is increased while the percentage of drying due to drainage and mechanical dewatering is kept constant.

Clearly, the correct balance between the content of disaggregating agent in the finished product, which determines the degree of disaggregation of the paper in terms of speed and quality of disaggregation, and the dry content, which may be as much as 30%, can be determined by a person skilled in the art, by simple tests on the installation described in the present invention.

The speed and quality of disaggregation of the paper is directly proportional to the content of disaggregating agent present in the finished product.

For a given content of disaggregating agent in the initial pulp, the dry content up to 30% can be adjusted according to the desired characteristics of disaggregation of the finished product.

A technician with ordinary experience in the art will also be able to allow for other factors such as the initial material (pulp) for forming the paper, the raw materials used, the type of disaggregating agent used (reference may be made to WO2013/124804) and other manufacturing conditions known in the industry.

The percentage by weight of disaggregating agent in the paper can vary, as has been seen, from about 3% to about 30%, being preferably from about 24% to about 30% to provide maximum disaggregation and maximum disaggregation speed, preferably from about 17% to about 23.9% to provide maximum disaggregation and a good disaggregation speed, preferably from about 10% to about 16.9% to provide good disaggregation and a good disaggregation speed, and preferably from about 3% to about 9.9% to provide imperfect disaggregation and a good disaggregation speed. Evidently, the temperature of the web during drying must also be taken into account, since excessively high temperatures cause deterioration of the web with dramatic consequences for its disaggregation. According to the present invention, the suitable temperature is in the range from about 90°C to about 130°C, preferably from about 90°C to about 100°C.

Additionally, the need to produce low grammage (30 - 40 g/m ² ) and the low physical- mechanical characteristics of the wet web make the problem of open draws even more critical than in the standard process. It is therefore necessary to move from the forming step to a first drying step without open draws, and a first open draw is acceptable in use only if the consistency of the web being formed is greater than about 30% dry, for example between 30% and 50% dry. Bearing these basic requirements of the method in mind, some possible layouts of the machine are outlined below.

Basic layout of the continuous machine

Figure 1 shows the basic layout of the machine according to the present invention, where A indicates sections a) and b), which are, respectively, a forming section and a section for drying by drainage, mechanical dewatering and/or evaporation, and B indicates sections d) and e), which are, respectively, a further evaporation drying section and a winding section.

The forming section and the winder may be of a conventional type.

The drainage, mechanical dewatering and evaporation may be carried out with any available technology, including those which are not conventional in the paper industry. By way of example, it is possible to use foils, vacuum foils, suction boxes, hot-air ovens, infrared ovens and microwave ovens.

In general terms, the installation for producing disaggregatable paper is as described in the exemplary embodiment of Figure 2, where A and B refer to the sections of Figure 1. The basic components of the installation (1) are described below. A pulp feed system (2) of a conventional type feeds a closed-loop forming fabric (9), with a draining breast roll. This fabric is also of a conventional type, and may be made of various materials, for example bronze, stainless steel or synthetic materials. Its function is to collect the pulp which arrives from the feed system (2) and direct it to the first drying section, composed of draining elements (the fabric itself) and mechanical dewatering elements (3), for example a suction box, which have the function of starting the drying of the pulp, and evaporation drying means (4), for example a hot-air or infrared oven.

In one embodiment of the present invention, a further evaporation drying system is provided, for example another infrared oven (5).

If desired, a controlled air blowing system (6, also referred to as "SAD") is provided, being placed, for example, under the fabric (9) at the position of the oven (5). The SAD system is composed, for example, of a blower system and a perforated plate, supplied by an air fan. Other conventional blowing systems may also be provided. The SAD system (6) is usually positioned after the draining elements and the mechanical dewatering means, for example at the start of the evaporation by evaporation drying means (4 and/or 5), or immediately after, or at any point after the start of the drying means, and may extend for any length desired by the machine designer, according to the characteristics of the web being formed.

The second evaporation drying section (7) may be of the conventional type, for example a series of heated rolls (see also the example of Figure 3, (28a)) or a hot-air oven.

Finally, the winding system (8) for forming the final reel is of a known type, for example a pope reel winder.

The method according to the present invention may be executed as follows. The initial pulp, at a temperature in the range from 10°C to 80°C, for the production of the disaggregatable paper is introduced into a forming box (2), which feeds a closed-loop fabric (9) with a large- diameter draining breast roll. The paper web that is formed, with a dry content of about 10%, comes into contact with a suction box (3), and leaves it with a dry content of about 17%. At this point, the paper web passes under an oven (4) of suitable length, equipped with infrared lamps. After passing through the oven (4), the paper web has a consistency of 25% and encounters a blower unit (6) which detaches the web from the fabric; it then enters an oven heated by infrared lamps (5), while being held in an elevated position by a perforated plate supplied with air by a fan. Both the blower unit and the perforated grid, forming the two components of the SAD (6), are positioned on the opposite side of the fabric (9) from that which supports the paper web being formed. On leaving the oven (5), the paper web, with a dry content of about 50%, is transferred to a fabric (10) in a hot-air oven (7) where it is finally dried (to a consistency of between 90% and 97%) and then passes to the pope reel (8) to form the paper reel. In an alternative embodiment of the present invention, with reference to Figure 2A, the method and the installation (1) for executing it are as described above, but the second dewatering section (7a) consists of a hot-air flotation oven.

Figure 3 (which refers to sections A and B of Figure 1) shows an exemplary diagram of a variant of the basic version of the machine (1) according to the present invention, illustrating the essential components. The machine (20) comprises a forming section (21) where the forming step is carried out, which comprises a conventional system of one or more forming rolls, which may be more or less sophisticated in terms of a low grammage of the web, an increase in production rate, and an increase in the web characteristics. Other possible forming devices are known, including, for example, a head box, which may increase the characteristics of the web as well as the production rate.

The drying section is essentially composed of a draining fabric (38) (a closed-loop product) which collects the pulp of water, fibres and disaggregating agent and allows the first step of drainage of the pulp to take place. This product may consist of synthetic fibres, stainless steel, or bronze. In this step, the web is progressively consolidated (dried) to a dry content of about 30% - 50%.

According to the present invention, the drying means installed on the draining fabric (38) are of two different types, namely mechanical dewatering and evaporation means. Figure 3 shows mechanical dewatering devices (22), (24), which, purely by way of example, may be foils, vacuum foils, or suction boxes, designed on the basis of the production characteristics of the machine. The evaporation drying systems (23), (25) may be, for example, hot-air and/or infrared ovens, ventilated or unventilated, also designed on the basis of the production characteristics of the line. In the exemplary embodiment of Figure 3, the mechanical dewatering and evaporation means are positioned alternately, starting with the mechanical means. Other arrangements may be used, provided that these means are arranged in such a way that the drying step is carried out with these means until the web has reached a dry percentage of about 30%, and that the evaporation drying means are arranged so as to complete the drying step.

The balance between the drying systems (using drainage, mechanical dewatering and/or evaporation) is essential for the purpose of obtaining the required percentage of disaggregating agent in the web. To obtain the same disaggregation of the web if the emphasis is on mechanical dewatering, preferably accounting for about 25% of the consistency of the paper web being formed, a higher concentration of disaggregating agent must be used in the pulp and in the drainage liquids. As regards evaporation drying, the control of the temperature of the web is important for the purpose of avoiding phenomena which may damage the disaggregation characteristics of the paper. According to the present invention, the suitable temperature is in the range from about 90°C to about 130°C, preferably from about 90°C to about 100°C. The controlled air blowing system (26), also abbreviated to SAD, has the purpose of facilitating the detachment of the web from the fabric, so that the wet web can be transferred to the next step of evaporation drying.

The SAD system (26) may be positioned after the mechanical dewatering means (24), for example at the start of the evaporation drying means (25), or immediately thereafter, or at any point after the start of the evaporation drying means (25), and may extend for any length desired by the machine designer, according to the characteristics of the web being formed.

In this part of the machine according to the present invention, there are no open draws.

The web therefore passes to the next evaporation drying section (28a), designed and constructed on conventional principles, with additional provision being made to avoid subjecting the web to the first open draw until it has reached a consistency of more than about 30% dry. In this section, a device (29) can be provided for spraying the disaggregatable paper web, with detergent for example, as described in WO2013/124704, with a drying section composed of an infrared oven (31) and a series of heated rolls (28b).

The device (29) for surface treatment, by spraying for example, may be provided in any version of the machine according to the present invention, including the basic version shown in Figure 2 and the other variants described in the present application.

A person skilled in the art may devise variants of the arrangement provided in Figure 3, for example by arranging evaporation drying means after the mechanical dewatering means without alternating them, provided that the machine conforms to the essential characteristics of the method proposed by the present invention.

Figure 4 shows a possible variation of section A, shown in Figure 1 , of the continuous machine of the present invention. In this embodiment of the machine (31), the forming system (32) is completely separate from the mechanical dewatering step. From the forming system (32), the draining forming fabric (33) transfers the paper web to a felt (40) where it comes into contact with the mechanical dewatering system (34, 34a, 34b). The figure shows how the passage between the first two steps takes place without any open draws. Evaporation drying means (35, 36) are suitably positioned to execute the method according to the present invention. In this exemplary embodiment, the first mezzo evaporation drying means (35) is positioned immediately after a first part of the mechanical dewatering means (34, 34a), and the means (35) is followed by another mechanical dewatering means (34b) and finally by a second evaporation drying means (36). This embodiment has the advantage of improving the uniformity of the moisture profile of the web.

A person skilled in the art may devise variants of the arrangement provided in Figure 4, on condition that the machine conforms to the essential characteristics of the method proposed by the present invention.

A first step of drying by drainage and mechanical dewatering (27) may be carried out on the felt (33) which transfers the web from the forming step to the next step. This separation of the forming step has the advantage of increasing the flexibility of the method. The illustrated system identified as (28a) in Figure 3 or (45, 46) in Figure 5 is a typical system used in papermaking. The wet paper web is made to adhere by a drying fabric (10; 39a; 51) to a series of rolls heated by saturated steam or another system. The requirements of the method according to the present invention have led to the design of a single line system which provides drying without open draws. The system may be made more powerful by the addition of hot-air hoods (53, Figure 5).

The winding system (not shown in Figure 4) is a standard pope reel type, but may be replaced with an axial winder, possibly with an automatic joint.

In an alternative embodiment of the present invention, shown in Figure 5, the method and the installation (41) for executing it are as described above for the embodiment shown in Figure 2, except that the first drying section (43, 44a, 44b, A), while still comprising draining elements (the fabric 43 itself and mechanical dewatering means 44a) and evaporation drying means (44b), does not include a blowing system. The paper web being formed, with a dry content preferably equal to or less than 25%, is transferred, without any open draws, to the second dewatering section (B) by means of a felt (51) which runs in contact with a series of heated rolls (45, 46). Also shown in the installation (41) are the fabric (43), the winding system (49) and the optional spraying system (50), and the felt (52) with the drying section composed of the infrared oven (47) and a series of heated rolls (48), similar to the section shown in Figure 3 (29 and 28b).

A person skilled in the art may devise variants of the arrangement provided in Figure 5, on condition that the machine conforms to the essential characteristics of the method proposed by the present invention.

In a preferred exemplary embodiment of the present invention, the disaggregatable paper 6 is as described in the aforementioned WO2013/124804. In particular, it is a paper soap disaggregatable in aqueous liquids, comprising: a. cellulose fibre pulp: 50 - 90% by weight; b. disaggregating agent: 3% - 30% by weight; c. at least one detergent. Preferably, the percentage of the pulp by weight in this paper is in the range from 80% to 90%.

Preferably, the percentage of the disaggregating agent by weight in this paper is in the range from 5% to 13%.

Preferably, the paper further comprises at least one of the following components: d. debonding agent: 2% - 8% by weight; e. dyeing agents: 0.01 % - 0.05% by weight; f. mineral pigments 0.1 % - 20%; g. retention agents 0.1 % - 5%.

The disaggregating agent is preferably a water-soluble substance, and is selected from the group consisting of polyvinylpyrrolidone, polyethylene glycol, xanthan gum, guar gum, polyquaternium polymers, pullulan, hydroxypropyl methylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, gelatin, carboxymethyl cellulose sodium salt, polyvinyl alcohol, sodium alginate, gum tragacanth, acacia gum, gum arabic, polyacrylic acid, methyl methacrylate copolymer, carboxyvinyl polymer, amylase, natural and modified starches, aluminium starch octenylsuccinate, hydroxypropyl starch phosphates, high-amylase starch, hydroxypropyl high-amylose starch, dextrin, pectin, chitin, chitosan, levan, elsinan, collagen, zein, glutane, soya protein isolate, milk protein isolate, casein, locust bean gum, karaya gum, carrageenan, gellan, agar, alginic acid and alginates, furcellaran, polyhydroxy acid polymers, and mixtures thereof; polysaccharides. Carboxymethyl cellulose sodium salt is the preferred agent.

Typically, this paper has a grammage in the range from 20 to 500 g/m ² .

The manufacture of the paper described in WO2013/124804 includes spraying with at least one detergent, and therefore the corresponding continuous machine for its manufacture, as described in the present invention, includes a spraying device, for example as shown in Figure 3 (29) or Figure 5 (50).

The present invention is additionally illustrated by the following examples. EXAMPLES

Example 1

A continuous machine for manufacturing disaggregatable paper

The installation for producing disaggregatable paper (1), shown in Figure 2, is composed of the following elements: a) a pulp feed system (2); b) a closed-loop fabric (bronze, stainless steel or synthetic) (9) with a draining breast roll which collects the pulp and allows the initial pulp dewatering to take place; c) a suction box (3); d) an infrared oven (4); e) a controlled air blowing system (6) composed of a blower system and a perforated plate supplied by an air fan; f) an infrared oven (5); g) a drying fabric (10); h) a hot-air oven (7); i) a pope reel winder (8).

The fibrous pulp as described in Example 1 of WO2013/124804 is fed via a forming box to a closed-loop bronze fabric with a large-diameter draining breast roll. The paper web being formed, with a consistency of about 10%, comes into contact with a suction box (3), and leaves it with a dry content of about 17%. At this point, the paper web passes under an infrared oven (4). After passing through (4), the paper web, with a consistency of 25%, encounters an SAD blower unit (6) which detaches the web from the fabric; it then enters an oven heated by infrared lamps (5), while being held in an elevated position by a perforated plate supplied with air by a fan. Both the blower unit and the perforated grid, forming the two components of the SAD, are positioned on the opposite side of the fabric from that which supports the paper web being formed. On leaving (5), the paper web being formed, with a dry content of about 50%, is transferred to a drying fabric (10) in a hot-air oven (7) at a web temperature in the range from 90°C to 130°C (7) where it is finally dried (to a consistency varying from 90% to 97%) and then passes to the pope reel (8) to form the paper reel. Example 2 A continuous machine for manufacturing disaggregatable paper

The installation for producing disaggregatable paper (1), shown in Figure 2A, is composed of the following elements: a) a pulp feed system (2); b) a closed-loop fabric (bronze, stainless steel or synthetic) (9) with a draining breast roll which collects the pulp and allows the initial pulp dewatering to take place; c) a suction box (3); d) an infrared oven (4); e) a controlled air blowing system (6) composed of a blower system and a perforated plate supplied by an air fan; f) an infrared oven (5); g) a hot-air flotation oven (7a); h) a pope reel winder (8).

The fibrous pulp as described in Example 1 of WO2013/124804 is fed via a forming box (2) to a closed-loop bronze fabric (9) with a large-diameter draining breast roll. The paper web being formed, with a consistency of about 10%, comes into contact with a suction box (3), and leaves it with a dry content of about 17%. At this point, the paper web passes under an infrared oven (4). After passing through (4), the paper web, with a consistency of 25%, encounters an SAD blower unit (6) which detaches the web from the fabric; it then enters an oven heated by infrared lamps (5), while being held in an elevated position by a perforated plate supplied with air by a fan. Both the blower unit and the perforated grid, forming the two components of the SAD (6), are positioned on the opposite side of the fabric from that which supports the paper web being formed. On leaving (5), the paper web being formed, with a dry content of about 50%, is transferred to a hot-air flotation oven (7a) kept at a web temperature in the range from 90°C to 120°C, where it is finally dried (to a consistency varying from 90% to 97%) and then passes to the pope reel (8) to form the paper reel.

Example 3

A continuous machine for manufacturing disaggregatable paper

The installation (41) shown in Figure 5 for producing disaggregatable paper is composed of the following elements: a) a head box (42); b) a draining forming roll (42a); c) a draining fabric (43) (a closed-loop product); d) a suction box (44a) (mechanical dewatering device); e) an infrared oven (44b); f) a drying felt (51): g) a series of heated rolls (45, 46); h) a heated air hood (53); i) a drying felt (52): j) a spraying section (50); k) an infrared oven (47);

1) a series of heated rolls (48); m) a pope reel winder (49).

The fibrous pulp described in Example 1 of WO2013/124804 is fed via a head box (42). The paper web is formed on a draining forming roll (42a). The paper web formed, with a consistency of about 10%, comes into contact with a suction box (44a), and leaves it with a dry content of about 20%. At this point, the paper web passes under an infrared oven (44b). After passing through the oven (44b), the paper web, which has a consistency of about 23%, is transferred to a felt (51) which runs in contact with a first series of heated rolls (45, 46), the roll (46) being coupled to a hot-air hood (53) at a web temperature in the range from 95°C to 120°C, bringing the paper web to a consistency in the range from 50% to 80%. After the paper web has been transferred to the felt (52) it passes into a surface treatment section (50), where the web is sprayed with a detergent -containing solution, and a subsequent drying section, composed of an infrared oven (47) and a series of heated rolls (48), where it is finally dried (to a dry content varying from 90% to 97%), and then passes to the pope reel winder (49) to form the paper reel.