HK1171988B - Fibrous sheet that disintegrates in water, process for manufacturing said fibrous sheet, core consisting of strips of said fibrous sheet - Google Patents

Description

Water-disintegrable fibrous sheet, method for producing said fibrous sheet, use of said fibrous sheet for core production

The present invention relates to the manufacture of disintegratable fibrous sheets, in particular paper sheets, and to a disintegratable fibrous sheet, in particular a paper sheet. In particular to the use of the sheet for manufacturing a core forming a roll support. The invention is used in the field of hygiene or household paper in the form of a core, in particular a support core for a toilet paper roll or tampon applicator.

Background

Sanitary or household papers, such as toilet tissue, paper towels or wipes, are in some cases wrapped around a core in the form of a roll.

The core is cylindrical, typically made of thick paper, and is discarded after the paper of the roll is used up. The core performs several functions:

as a support for the winding of the paper during the manufacture of the roll paper. Usually, rolls made of very wide main sheets, also called large-diameter rolls, are wound on tubes of a corresponding length, and the resulting rolls are sawn into individual rolls of the desired width.

It withstands the internal stress of the roll of paper keeping the central hole open and preventing the internal turns of the winding device from collapsing; and

it withstands the compression or transverse forces along its axis that it is subjected to during transport or during various handling operations before use, thus maintaining the profile of the roll.

The core is typically obtained by spirally winding and gluing one or more flat thick paper strips around a cylinder.

Flat cardboard is an inexpensive material that can be made from recycled fiber. It is also light and mechanically strong enough for this purpose.

However, it has the drawback of not being reusable, of being difficult to use in another form after the paper roll has been used up and of becoming waste.

In the case of toilet paper, it is not recommended to attempt to discharge it with the waste water to treat a standard core, which, although consisting mainly of papermaking fibers, disintegrates slowly on contact with water, is generally not removable from the toilet bowl, or it may block or clog the toilet bowl drain before flushing with a stream of water.

The applicant set the aim to produce a core for paper rolls which can be easily drained together with the waste water of household sanitary appliances.

More specifically:

the core must disintegrate rapidly on contact with water;

the material must disintegrate in water at a speed sufficient to expel it before a plug is formed; for the same mass, it must disintegrate at a rate comparable to that of toilet paper normally making up a roll;

the core must have crush resistance of the same order of magnitude both radially and axially, as the thick paper it is intended to replace;

the core must be as easy and simple as the preparation of a conventional thick paper core; and

the core must be made of a reusable material; it should not have a negative impact on paper recycling processes and water treatment equipment processes.

Prior Art

Sheet-like or other forms of products made from papermaking fibers and starch are known.

EP415385 describes the preparation of paper sheets incorporating a water-insoluble modified starch (starch urea phosphate, which gelatinizes during drying) which has a relatively low gelatinization temperature, i.e. between 35 ℃ and 55 ℃. The aim is to improve the dry strength of the resulting sheet and to avoid the wire-clothing in the paper machine during the manufacturing process.

EP1630288 describes an embossed and impregnated paper sheet, disintegratable in water, designed to be used as a cleaning sheet, such as a wet wipe. It contains a water-soluble binder, such as a polysaccharide or synthetic polymer, and an aqueous agent associated with the agent that produces a water-soluble binder that is temporarily insoluble. According to the examples given, the sheets disintegrate within 30-40 seconds, the disintegration rate being determined using standard methods referred to JIS P4501 for 0.3g square sheet samples.

US6169857 describes a biodegradable product, for example in the form of a sheet. It consists of a reinforced starch matrix such as papermaking fibers and is obtained by molding. The aforementioned mixture consists at least of ungelatinized starch, fiber and water. The product is obtained by molding the mixture. To form the film, a polymer, such as a cellulose ether, is added on the surface, which prevents sticking during the manufacture of the product.

Disclosure of Invention

The quality of the core depends at least to some extent on the component fibre sheet.

Fibrous sheet made mainly of papermaking fibers

According to the invention, the basis weight of the fibrous sheet is between 20 and 1000g/m²In accordance with the wet papermaking process and having a disintegration time in water of less than 120 seconds, said fibrous sheet comprising 10-70% starch and at least 30% papermaking fibers, based on the total weight of the dry fibrous sheet.

The term "disintegration" complies with the definition of total disintegration given in the standard NF Q34-020, i.e. there are no more significant tablets and the tablets are uniformly dispersed. The fiberboard according to the present invention is disintegratable when its disintegration time in water is less than 120 seconds.

The term "wet-laid papermaking process" refers to a method of making a paper sheet using wet-end sheet formation. More specifically, the process comprises a pulp and furnish preparation stage, a wet forming stage, a pressing stage to remove water, and a drying stage. The pulp preparation stage involves mixing the different components, including fibres, fillers and additives, with water to obtain a suspension or furnish. The wet forming stage may be carried out on a platform such as a fourdrinier table or any other cylindrical forming apparatus. The headbox may be provided with one or more jet distributors. The pressing stage involves removal of water by mechanical pressing of the web. The drying section may comprise a conventional dryer such as a drying drum, Yankee dryer, vented drying cylinder, infrared dryer, etc. to remove water by heat exchange. The sheet thus obtained is then wound on a reel as a final product.

The terms "cellulosic", "cellulosic fiber" and the like are intended to include any fiber containing cellulose as a major component. "papermaking fibers" refers to cellulosic fibers, including virgin or regenerated (secondary) cellulosic fibers or fiber blends containing reconstituted cellulosic fibers. Cellulosic fibers suitable for making the fibrous sheet of the present invention include: non-wood fibers such as cotton fibers or cotton derivatives, abaca, kenaf, ayurvea, flax, Phragmites communis, straw, jute, bagasse, feather down fibers, and pineapple leaf fibers; and wood fibers such as those from deciduous and coniferous trees, including softwood fibers, such as northern and southern softwood kraft fibers; hardwood fibers such as eucalyptus, maple, birch, aspen, and the like. Papermaking fibers used in connection with the present invention include natural pulp derived fibers as well as reconstituted cellulosic fibers such as lyocell or rayon. Pulp-derived fibers are separated from their raw materials by any of a number of pulping processes well known to those skilled in the art, including kraft pulping, sulfite pulping, polysulfide pulping, soda pulping, and the like. If desired, the pulp may be bleached chemically including using chlorine, chlorine dioxide, oxygen, alkaline peroxide, and the like. Natural pulp-derived fibers are referred to herein simply as "pulp-derived" papermaking fibers. The product of the invention may comprise virgin or recycled fiber and lignin-rich tubular fiber of high coarseness, such as bleached chemical thermomechanical pulp (BCTMP). Pulp derived fibers therefore also include high yield fibers such as BCTMP as well as thermo-mechanical pulp (TMP), chemical thermo-mechanical pulp (CTMP) and Alkaline Peroxide Mechanical Pulp (APMP). "furnish" and like terms refer to aqueous compositions used in the manufacture of paper products, including papermaking fibers, optionally wet strength resins, debonders, and the like.

Kraft softwood fibers are low yield fibers made from softwood materials including northern and southern softwood kraft fibers, douglas fir kraft fibers, and the like, by the well known kraft (sulfate) pulping process. Kraft softwood fibers typically have a lignin content of less than 5 wt%, a length weighted average fiber length of greater than 2mm, and an arithmetic average fiber length of greater than 0.6 mm.

Kraft hardwood fibers are made from hardwood resources, i.e., eucalyptus, by the kraft process, also typically having a lignin content of less than 5 wt%. Kraft hardwood fibers are shorter than softwood fibers, typically having a length weighted average fiber length of less than 1.2mm and an arithmetic average length of less than 0.5mm or less than 0.4 mm.

Recycled fiber may be added to the furnish in any amount. While any suitable recycled fiber may be used, a relatively low amount of recycled fiber from wood pulp is preferred in many cases, for example, recycled fibers having a lignin content of less than 15 wt% or less than 10 wt% may be preferred depending on the furnish mixture used and the application.

In addition, the fibrous sheet according to the present invention may further contain non-cellulose fibers such as synthetic polymer fibers and the like. The term refers to fibers made from synthetic polymers such as polyesters, nylons, and polyolefins, among others. Polyesters are generally obtained from aliphatic or aromatic dicarboxylic acids and saturated aliphatic or aromatic diols by known polymerization processes.

More specifically, the fibrous sheet has at least one of the following characteristics:

-the starch is substantially homogeneously distributed throughout the thickness of the fibrous sheet. The term "substantially uniform" means that the starch is distributed throughout the thickness of the sheet to provide the majority of the connections between the fibers, and that the starch is also present on the outer surface of the sheet.

-comprising 15-40%, preferably 20-35% starch, based on the total weight of the dry fibrous sheet.

-a basis weight of 100 and 600g/m²Preferably between 130 and 400g/m²In the meantime.

-8×9cm²The sheet sample of (a) has a water disintegration of less than 50 seconds, preferably less than 35 seconds, more particularly less than 15 seconds, measured according to the NFQ34-020 standard.

-the loss of strength measured according to the bench test reported in the specification corresponds to the loss of strength of the sheet sample when an angle of at least 85 °, preferably 88 ° -90 °, is formed after wetting with water for 6 seconds.

-the residual strength of the sheet in the wet state compared to its dry state, measured according to the ring pressure test described in the following description, is less than 1%.

The sheet contains additives for providing a function other than starch, such as disinfectants, detergents, dyes or fragrances.

Use of sheets, e.g. as cores

The fibrous sheet of the invention is used for the manufacture of a support roll (roll), in particular a roll of paper, more particularly a roll of cellulose batting or toilet paper, one or more strips of said sheet being spirally wound on a cylinder. The choice of basis weight of the sheet depends on the number of tapes called tows that make up the core.

The structure of the core according to the invention thus has the advantage of controlled disintegration together with strength compared to thick paper.

The present invention is also directed to toilet paper rolls comprising cores made therefrom. Thus, when the roll is used up, the core can be discharged and flushed away together with the waste water of the household sanitary appliance, since it disintegrates very rapidly.

The fibrous sheet according to the invention may also be used in tampon applicators.

The fibrous sheet of the present invention can be obtained by a method using starch insoluble in water at the incorporation temperature (method I) or by a method using starch (insoluble and/or water-soluble) (method II).

Method I for making sheets from starch that is insoluble in cold water.

A method of making a fibrous sheet that disintegrates in water in less than 120 seconds, comprising the steps of preparing a pulp by suspending the fibers in water, forming a fibrous sheet from the pulp, and drying. The method is characterized by further comprising the steps of adding a starch that is insoluble in water at the incorporation temperature prior to said drying step and drying the starch-containing sheet at a temperature sufficient to gelatinize at least some of said starch. The aim is to prepare a starch that is soluble in water so that the sheet can disintegrate.

The expression "water-insoluble starch" is understood to mean a starch which, when incorporated, mixed with water and stirred, forms essentially a suspension. In other words, the starch granules or pellets remain mainly suspended in water. When the stirring was stopped, the starch granules precipitated. The temperature of incorporation is below the gelatinization temperature of the starch.

Thus, from the sheet a minimum basis weight, e.g. 150g/m²Initially, most of the starch particles are retained by the fiber mat and therefore are not entrained in the waste water during dewatering in the forming table or press. The degree of starch retention is therefore high.

Starch comprises natural products of plant origin, such as wheat, corn, potato, rice, tapioca or sorghum starch, as well as other starches composed of high molecular weight polymers or polysaccharides. Plant material is processed by grinding-maceration and centrifugation to extract starch. Native starch corresponds to the extracted product without molecular modification. Native starch is insoluble in water-it acts as a filler. The starch is mixed into excess water under agitation to form a starch suspension. When the temperature of the starch suspension rises, water penetrates into the starch granules, which swell, and the suspension transforms into a colloidal solution, thickens, gelatinizes and becomes viscous. The gelation temperature depends on the plant: 60-72 ℃ of corn; 60-65 ℃ of wheat; 52-64 ℃ of cassava starch; potato at 58-66 deg.c. Upon continued heating, the granules break, and the macromolecules that make up the starch emerge from the granules and dissolve in the water. For this gelatinization and dissolution of starch, the presence of sufficient amounts of water is essential

Starch also includes products derived from native starch, which have been converted by physical, chemical and physicochemical or biological treatment, for example enzymatic treatment, and derivatized or modified starches, for example cationic, anionic, amphoteric, nonionic or crosslinked starches, and products resulting from the hydrolysis of starch, for example maltodextrins. These starches are referred to as modified starches.

Thus, in the range where it is insoluble in water, a preferred starch that can be used in the process may be a modified starch.

Preferably, tuber starch, such as potato starch, is used because the granules are relatively coarser than the granules of other starches, such as corn starch, and have a higher retention in the sheet.

Preferred starches are anionically modified potato starches, such as the Starch sold under the trade name Perfectacote A35 from Avebe, or nonionic Starch sold under the name Stackote 6 from National Starch. Preferably, the starch presents a degree of substitution of 0.01 to 0.07, wherein the substituent group is a carboxyl group. These starches have a low viscosity at the gelatinization temperature (52 ℃ for Perfectacote A35) and remain very stable over time. For the purposes of the present invention, this property is suitably well distributed in the fibrous sheet.

Preferably, the aim is to gelatinize all the starch present in the sheet and to provide a starch distribution throughout the thickness of the sheet.

The method according to the invention advantageously comprises a step of pressing the sheet before the drying step.

The water-insoluble starch is incorporated into process water, which is usually at a temperature below 50 ℃.

The water-insoluble starch is advantageously incorporated into the pulp upstream of the forming table. The starch suspension can thus be mixed homogeneously with the pulp fibres.

Although this is not optimal, it is also foreseen to incorporate the water-insoluble starch while the sheet is on the forming wire, in particular by spraying it onto the sheet or by other common application methods.

The water-insoluble starch is supplied in an amount sufficient to impart the above-mentioned properties to the sheet.

According to another feature, the sheet is dried with a gradually rising temperature so as to completely gelatinize the starch and to make it soluble. By gradually increasing the temperature, it is possible to control the amount of water present in the sheet at the gelation temperature and maintain a sufficient amount of water to break all the particles. This makes the fibrous sheet disintegratable.

The invention does not exclude the possibility of adding further steps, including the precipitation of a unit weight of starch by pressing in a drying zone to impart specific properties to the sheet, provided that the additional layer does not impair the disintegration properties of the sheet.

Method II for preparing sheet from water-soluble or water-insoluble starch.

A process for preparing a fibrous tablet that disintegrates in water in less than 120 seconds is characterized by comprising the steps of: suspending fibers in water, forming at least a first fiber layer and a second fiber layer from said fibers, depositing starch on the second fiber layer, depositing the first fiber layer on the second fiber layer, joining the two layers together into a fibrous sheet and drying the fibrous sheet.

The number of layers is not limited to two-the sheet may comprise at least three layers, for example up to about ten layers. The starch may be precipitated between the two layers after they have been formed, but this is not mandatory.

The starch is supplied in an amount sufficient to impart the above-described properties to the sheet.

When a water-soluble starch is selected, its rate of dissolution depends on the amount of water present in the fibrous layer formed by the wet treatment. It is therefore capable of imparting mechanical strength in the dry state and solubility in water to the sheet.

Typically, the water-soluble starch is a modified starch comprising a maltodextrin compound. Some examples of such starches are AVEDEX (dextrinised potato starch) from AVEBE, CARGILL MD01904 (maltodextrin) from CARGILL.

When a water-insoluble starch is chosen, it is referred to as starch in the description of method I.

According to a preferred embodiment, the starch is supplied in dry form in the form of a powder or a tablet or a film. This embodiment is advantageous in that the starch is activated by the water present in the fibre layer without the need to provide additional water.

According to another feature, the sheet is punched before drying or calendered after drying to obtain a density after drying of 450kg/m³To 650kg/m³The sheet in between.

Use of starch

The invention uses water-insoluble starch for its purpose to prepare a starch with a basis weight of 20-1000g/m²A fibrous sheet made according to a wet papermaking process and disintegrating in water in less than 120 seconds, said fibrous sheet comprising 10-70% starch and at least 30% papermaking fibers, based on the total weight of the dry fibrous sheet.

According to another embodiment of the present invention, water-insoluble starch and water-soluble starch are used in combination to prepare such a fibrous sheet.

Detailed Description

Two non-limiting exemplary embodiments of the present invention will now be described in greater detail in conjunction with the accompanying drawings, in which:

figure 1 shows a side view of a paper machine for making heavy paper sheets according to the invention, adapted to the method I for making cores according to the invention.

Figure 2 shows a side view of a paper machine used to make heavy paper sheets according to method II.

FIG. 3 shows a (× 100) magnification electron micrograph of a cross section of a sheet produced according to method I of the present invention before drying.

FIG. 4 shows a (2000) magnification electron micrograph of a cross section of a sheet made according to method I of the present invention after drying.

Preparation according to method I

Method I is carried out on a conventional paper machine 1 as shown in fig. 1. It shows the upstream end to the downstream end of the direction of preparation. The pulp is contained in a stock chest 2, in which the fibres are present in suspension and incorporated with additives; the pulp is fed into a headbox 3 which contains in particular a pulp distributor in the form of a knife edge designated "jet" extending over the entire width of the machine. The pulp is deposited on the endless wire 4 of the forming table 5. The web 4 forms a loop and runs endless around parallel rolls supporting its table. It vibrates laterally to reciprocate, promoting sheet formation and dewatering. The fibers are aligned with the direction of travel of the web. Upon leaving the table, the sheet contained 75-85% water. The sheet is introduced into the press zone 6 where the water content is reduced to 60% or 70%. The press comprises several pairs of gummed rollers. This operation also increases the density of the sheet and improves its surface finish with mechanical action.

The sheet then enters the dry end of the paper machine, referred to as the drying zone, which contains a plurality of dryer cans 7. The drying cylinder 7 is a cast iron rotating cylinder internally heated with steam at a temperature sufficient to gradually evaporate the water contained in the sheet until a dryness of at least 90% is reached. Typically, the surface temperature of the drum is about 95 ℃. The sheet is held against the dryer can by a heavy cotton felt or a dryer fabric composed of cotton and rayon.

The usual machines for preparing printing or writing paper also comprise a size press for surface treatment and for precipitating a suitable composition, and optionally a semi-dry calender or calender, before the paper is wound onto a reel. This reel is then used as the primary reel in a subsequent converting step.

In the present invention, the paper is substantially dry in the drying zone before being rolled up. To make sheet C of the present invention, starch is added to the wet end of the paper machine prior to pressing. Preferably, the starch is incorporated in the form of a suspension in water.

The starch may be deposited by spraying on a sheet which is moved along the forming table 5 to rest on the wire 4.

The starch may be further introduced upstream prior to sheet formation. The advantageous zone into which it is introduced is located at the inlet of the transfer pump between the stock chest and the headbox. Thus, the starch remains in suspension in the manufacturing composition introduced into the headbox.

According to an important feature of the process I according to the invention, the starch introduced at this stage is insoluble in water. As the sheet passes through the drying zone, it becomes soluble. The temperature of the continuous drying cylinder is advantageously adjusted by gradually raising the temperature of the sheet until the gelatinization temperature of the starch it contains is reached. The temperature of the continuous cylinder can be controlled between 60 ℃ and 100 ℃. The aim is to keep sufficient water in the sheet to allow the gelling to proceed efficiently and to make the starch soluble. If the amount of water is insufficient, a part of the starch is not gelatinized. Once the starch in the sheet has gelatinized and become soluble, the sheet can continue to be dried to a desired dryness.

Pressing and drying are adopted to obtain the required final water content of the product.

The sheet thus continuously produced is rolled up for subsequent use.

The manufacturing parameters of the sheet C are determined to obtain the core of the desired properties.

The fibres used are long, short or regenerated fibres and may also be mixtures thereof.

Water insoluble starches are preferred so that the insoluble particles are large enough in size to not easily filter through a wet sheet, e.g., having a particle size greater than 20 microns.

Other additives may also be incorporated to provide other functions, such as disinfectants, cleaning agents or fragrances.

Retention agents may also be added to improve retention of starch in the sheet, particularly for lightweight sheets.

Preferably, the starch is coloured in order to check the correct distribution of the binder in the thickness. In addition, it represents an improvement in aesthetics.

Experimental manufacturing test on a small sample test fourdrinier papermaking machine according to method I

The machine contains 3 drying units, each consisting of two drums.

A270 g/m starch product with a starch content of about 33% was produced²The sheet of paper of (1).

At 10m³Pulp with a consistency of 2.5% was prepared in the stock chest.

The pulp mass is 250kg and consists of the following substances:

35% starch, i.e. 97.2kg starch; and

162.5kg of fibres, one quarter of which is long fibres and three quarters of which is short fibres.

After mixing, the contents of the mixed chest are transferred to the chest of the machine.

480m paper was produced.

The dryness is:

-between 16-17% on leaving the fourdrinier machine;

-upon leaving the press, 57%; and

-upon rolling, 91%,

the dry weight was 243g/m²。

The temperatures of the six drying drums were controlled so that the temperatures gradually increased.

The starch content measured in the sheet averages 33% relative to the total dry weight of the sheet.

A description will now be given of a production example according to method II

According to the manufacturing embodiment shown in fig. 2, the paper machine 100 includes a first unit 102 for wet processing to form a layer of papermaking fibers on a fourdrinier table (shown here) or a cylinder mold. Layer C' 1 is formed by settling pulp, formed by papermaking fibers suspended in water on a permeable moving wire 122 of the first forming table 120, through a headbox 121. The web forms a loop and runs endless around parallel rolls that support it. Layer C' 1 undergoes a first dewatering step as it moves along the wire 122.

The first fibre layer C '1 is attracted by the draw blankets which are shifted around the parallel idlers in a loop, one of which 131 presses against the first layer C' 1, at the end stroke of the flattened portion of the forming table 120 around the roller 123, partial dewatering occurs. The first layer C '1 is conveyed by the blanket to a second fourdrinier table 140 of the second unit 104 for forming a second layer C' 2 of papermaking fibers. Said layer C' 2, like the first layer, passes through a headbox 141, where it is formed by depositing a pulp containing a fibre suspension of a moving wire 142 of a table 140. The fibrous layer C' 2 thus formed is dewatered through a permeable wire like the first layer. The draw blanket is pressed against the second fibrous layer C' 2 by roller 132 to remove the second layer at roller 143 at the end of station 140. The two fibre layers are joined together to form a sheet C' which is led to the gap left between the two rolls of the press 105 for extracting a further part of the water from the two layers when sheeting. The web is then directed to a drying unit (not shown), which may be conventional. In such a configuration of multiple-produced sheets, the number of layers is not limited to two.

To manufacture the sheet C' of the invention, the device 106 for depositing starch L in powder form is placed upstream of the two cylinders 132 and 143. The device used is such that the powder is distributed uniformly in the desired amount over the width of the second fibre layer C' 2 and in a regular manner in the running direction of the machine. An apparatus comprising a product storage hopper, a product metering apparatus and a vibrating brush is used to meet all of these conditions. In commercial manufacture, the layer of papermaking fibers, here C' 2, formed by the wet process and upon which the starch is precipitated, has a dryness of about 10% to about 15%.

The water-soluble powdered starch is deposited on the second layer of papermaking fibers C' 2-before the two layers are placed against each other and pressed together-when the layers are sufficiently dehydrated and have a dryness sufficient to retain the product in the structure of the layers and to limit the removal of part of the starch with the dehydrated water.

The deposited starch is sandwiched between the two layers thus formed, still in wet form, and reacts with the residual water in each layer.

The fiber layer/starch/fiber layer composite is conveyed by blanket 130 to press zone 105 for operating conditions therein, and then into the area of the machine where the sheet is dried.

Whether or not related to the manner in which the powder is deposited, there may be other ways to form additional layers to form a sheet that may contain, for example, at least ten layers.

The sheet thus continuously produced is rolled up for subsequent use.

The manufacturing parameters of the sheet C are determined to obtain the core of the desired properties.

The fibres used are long, short or regenerated fibres and may also be mixtures thereof.

Other additives may be incorporated to provide other functions, such as disinfectants, cleaning agents or fragrances.

Preferably, the starch is coloured in order to check the correct distribution of the starch on both sides. In addition, it represents an improvement in aesthetics.

The deposition amounts were 35 and 150g/m²In the meantime.

The amount of starch in the sheet is thus from about 10% to about 70% of the total weight of the sheet after drying.

The density of the pressed fiber sheet is 450kg/m³And 650kg/m³In the meantime.

When incorporating dry, water-soluble starch, it is advantageous to use water in both layers to activate the starch. Pressing also ensures the correct distribution of starch in the majority of the fibres.

Manufacturing core

The paper sheet is cut into narrow strips or bundles and then spirally wound around a cylinder. Adhesive is applied to the overlapping portions of the turns to bond them together to form a rigid tube. Usually for the core of a roll of toilet paper, one or two bundles are wound.

The techniques for making the core are known to each investigator. It is adjusted according to the properties of the binder within the limits necessary to take into account the rapid disintegration of the tapes that join the bundles together with the adhesive.

Testing

Core compression, disintegration and toilet discharge tests with sheets obtained according to method I

The characteristics of the single strand core a prepared according to manufacturing method I are as follows:

-weight of sheet: 270g/m²；

-quality of the fibres: a long/short fiber mixture in the form of virgin pulp;

-starch parameters: PERFECTACETE A35 (modified water insoluble starch) sold by Avebe;

amount of starch retained by the decorative sheet: 90g/m²33% starch;

number of cylinder wall thicknesses: 1;

weight of the inner wall of the cylinder: 270g/m²(ii) a And

diameter and length of the cylinder forming the core: 40mm and 97mm respectively.

Core compression test:

the transverse compressive strength of the core was measured using the following method.

The core to be tested is first cut into a cylindrical portion delimited by two opposite faces perpendicular to the axis of the cylinder, said portion having a length parallel to this axis of 50 mm.

The cylindrical portion is then placed between two metal plates of a testing machine, the plates being parallel to each other and initially separated by a distance slightly greater than the length of the cylindrical portion.

The cylindrical body portion is positioned such that the axis of the cylinder is oriented perpendicular to the plane formed by the one or other plates.

The cylindrical body part is then compressed between the two plates, measured at a compression distance of 15mm, and the force at this point is recorded in newtons.

Incidentally, the resistance represented by the core is measured up to its maximum value, i.e. just before the core is irreversibly damaged.

Take 5 measurements at a time and calculate the average of the measurements.

The result obtained and made from a bundle of thick paper also had a density of 280g/m²The results for the control core for the inner wall weight are given together in the table below.

	Weight (D)	Quality of	Transverse compressive strength
				Thick paper contrast core	280g/m2	3.9g	272.8±9.6N
Test core A	270g/m2	3.6g	294±12.5N

This therefore indicates that the cores according to the invention containing 33% starch have a transverse strength at least equal to that of a conventional cardboard core.

It is known that the main pressure to which the core is subjected during the production/roll transfer cycle is substantially exerted on the edges, and therefore the core according to the invention can be considered fully satisfactory.

Core disintegration test:

the disintegration of core A manufactured as described above was measured according to the NF Q34-020 standard.

The principle consists in stirring a sample of the product in a specific volume of water. The time required for the sample to disintegrate was measured.

This test is applicable to toilet paper samples substituted with sheet samples according to the invention and to cylindrical samples formed into cores according to the invention. More precisely, the sheet sample is a 9cm by 8cm sample, i.e. 72cm area²The core sample was a cylindrical sample having a length of 5 cm. Stirring speed one of the standard methods: 800 rpm.

The materials, equipment, and methods of operation are described in detail in the standards. It should be noted that complete disintegration corresponds to the moment when the piece of sample should move from the bottom of the beaker to the top of the stirrer, in other words when there is no longer a large piece under the rotor blade and when the piece is evenly dispersed. At this time T, it is no longer possible to observe a significant change in the paper state between time T and time T +5 seconds. The water used for this test was tap water.

It was observed that the sheet samples according to the invention disintegrated very easily. The time required for the sheet structure to disintegrate is less than 15 seconds and the fiber suspension is obtained in less than 60 seconds.

Having a thickness of 280g/m²The heavy paper control core sample started to break only after 30 seconds, and the sheet was converted into a sheet after 3 minutes. Still have a size greater than 1cm after 10 minutes²The sheet of (1).

A composition of 270g/m was also observed²Core samples according to the invention formed of individual strips of weight have a water ratio of 280g/m²The similar thick paper core obtained by winding a single thick paper tape of a weight disintegrates more quickly.

The term "similar core" should be understood to mean a core having about the same diameter and the same length as the core of the present invention.

The core sample according to the invention disintegrates more rapidly than a similar thick paper core. This is because the core samples according to the invention disintegrated in 10-15 seconds and a fiber suspension was obtained in less than 60 seconds.

The number of turns for the control core sample was turned on after about 60 seconds and the control sample was in a large sheet state after 7 minutes. After 10 minutes, the dimensions remained larger than 1cm²The sheet of (1).

Also, again by comparison, 400g/m in the Afnor NF Q34-020 test was observed²The two plies of the thick paper core were separated by a number of turns at 60 seconds and the core began to disintegrate after 3 minutes. The disintegration was complete after 10 minutes, but thick paper still remained.

Core discharge test:

the discharge of the core from the sanitary household appliance is detected on the basis of the test method described in the guidelines published by EDANA (european disposables & nonwovens association) for the lower row of toilets (FG 510.1TIER 1 toilet bowl & drain pipe gap test).

In the test method, the performance of the device, the test conditions and the test procedures are defined.

More precisely, two steps were studied when applying this test to the core:

-1) draining the core down from the toilet bowl: the core must disappear from the tank after flushing; and

-2) discharging the core from the drain.

The equipment used for this test was a conventional toilet, containing a floor standing sink, a flush mechanism, a flush tank and a drain. The drain is a clear plastic tube so that changes in the product draining down the tank can be displayed. The tube has a diameter of 100 mm, a length of 20 m and an installation slope of 2%.

The method comprises introducing a series of ten cores into a tank by: the core is thrown into the slot and then a flush is performed. The volume of the rinse water was 5.5 liters. It is then checked whether the core has been ejected from the slot and the position in the tube is recorded. This operation was repeated with ten cores, each time recording the position of the core still in the tube. Finally, complete expulsion of the core is recorded upon exiting the tube.

Cores according to the invention, i.e. single bundles 270g/m²The core, was tested and passed the lower slot discharge test and the test discharged from the tube.

Similar 280g/m²The thick paper single bunch core did not even pass the lower slot discharge test.

Compression and disintegration testing of cores made from sheets obtained by Process II

Cores were prepared using method II.

The properties of the cores produced were as follows:

-weight of each fibrous layer: 45g/m²；

-quality of the fibres: a long/short fiber mixture in the form of virgin pulp;

-water soluble starch parameters: AVEDEX from AVEBE;

amount of starch retained by the decorative sheet: 90g/m²50% of starch

Number of fibrous layers: 2;

-weight of sheet: 180g/m²；

Number of thicknesses of inner walls of the cylinder: 2; and

weight of the inner wall of the cylinder: 360g/m²。

The water-soluble starch is chosen such that it dissolves rapidly at high concentrations.

The laboratory fabrication was performed as follows:

a layer of 10% dryness fibres was formed, deposited on a wire, starch in powder form was deposited, joined to another layer of 10% dryness fibres, dewatered by roller pressing and the layers joined, the sheet thus formed was taken out and dried between two metal wires at 110 ℃.

The cylindrical core is then manufactured from the two plates formed as above.

The diameter and length of the cylinder forming the core were 40mm and 97 mm.

Core compression test:

the compressive strength of the core was measured in both flat compression and transverse compression.

Take 5 measurements at a time and calculate the average of the measurements.

The result obtained and a paper having a thickness of 365g/m made from a bundle of thick paper²The results for the control core for the inner wall weight are given together in the table below.

	15mm flat compression	Transverse compression
			Thick paper contrast core	5.64±0.50	272.8±9.6
Core D containing 30% starch	6.15±0.92	118±25
			Core E containing 50% starch	12.11±1.55	265±41

Data represented by N

The table thus shows that the cores according to the invention containing 50% starch have a transverse strength similar to that of the conventional thick paper cores, and in this case the flat compressive strength is greater than that of similar cores made of thick paper.

Given that the main pressure to which the core is subjected during the production/roll transfer cycle is substantially exerted on a plane, the core according to the invention can be considered fully satisfactory.

Core disintegration test:

the disintegration of the cores manufactured as described above was determined according to the NF Q34-020 standard.

The core was found to be very brittle, breaking the structure in less than 10 seconds and obtaining a fiber suspension after about 30 seconds.

It was also observed that the core samples according to the invention had a water ratio of 280g/m²The similar thick paper core obtained by winding a single thick paper tape of a weight disintegrates more quickly.

The core ratio according to the invention thus consists of 280g/m, whether or not there is stirring²The heavy paper core formed by a single strip of weight disintegrates more rapidly.

Fibrous sheet shown in fig. 3 and 4

FIG. 3 is an enlarged photograph of a cross-section of sheet 200 prepared according to method I of the present invention taken with an electron microscope, before drying. The cross-section of the sheet is the plane between the arrows depicted on fig. 3.

The starch granules 202 are substantially uniformly distributed throughout the thickness of the sheet prior to the drying stage.

Fig. 4 is an electron microscope magnified photograph of a portion of a sheeting 300 according to the present invention. We observed that the papermaking fibers were coated with starch. The starch forms a network 302 throughout the sheet that is replaced with a portion of hydrogen bonds to link the fibers together. When the sheet is contacted with water, the starch absorbs water and dissolves rapidly. Since the fibers are no longer bound by starch, they separate from each other very quickly.

This phenomenon can explain the rapid disintegration of the sheet when it is wetted and the loss of adhesion and mechanical properties.

Comparative tests were performed on the same weight of the fiber sheet according to the invention and thick paper.

Three tests were performed: testing disintegration; bench test and ring pressure test.

-Disintegration testAs described above. Control NF Q34-020 standard at 8X 9cm²The test was performed on a fiber sheet or thick paper sample while using a stirring speed of 400 revolutions per minute. The water temperature was 20 ℃.

-Bench test

This relates to an internal test method for determining the loss of stiffness when a sample is wetted.

Cut rectangular samples 2.54cm wide and 13cm long were measured in the machine direction.

A stage having a horizontal plane, a vertical plane, and a straight edge at the intersection between the horizontal plane and the vertical plane is used. The sample was laid flat on a table and perpendicular to the edge. A portion of the sample (10cm) extends beyond the edge.

In the dry state, the angle of the sample to the plane was 0 °.

The sample was wetted using an electrokinetic burette, the endpiece of which was placed 1cm above the test piece: 3ml of water was supplied within 6 seconds. The water is deposited in the center of the test piece above the edge, at which point the sample makes an angle with the horizontal.

Once wetted, the sample was crimped around the edge: the bend angle relative to the horizontal plane was recorded 6 seconds after the water was delivered.

Ring pressure test

The loss of wet strength of the sample was determined by determining the ratio of the cross-directional compressive strength in the wet state to the dry state.

Cut specimens 15mm wide and 152.4mm long were measured in the longitudinal direction.

The sample was placed between two plates fixed on a ring support (as described in standard ISO 12192: 2002) and then a compressive force was applied at a rate of 10 mm/min. The maximum resistance was recorded.

For testing in the wet state, the samples fixed on the supports were immersed in water in a time of less than 2 seconds. The test was performed immediately after the impregnation.

Samples E2, E3 and E5 are laboratory prepared samples. Sample E6 is a small sample test sample and E4 is an industrial test sample.

Samples of sheet produced according to methods I and II (E1 to E6) were tested, as were thick paper control samples (E7 and E8) of approximately the same weight. The fibers used are fibrils.

The detailed composition and characteristics of the sheet samples are reported in the table. The disintegration time, strength loss and residual wet strength versus dry strength results tested according to the disclosed test methods were excellent.

Claims (29)

1. The weight of the paper is 20-1000g/m²A fibrous sheet having a disintegration time in water of less than 120 seconds as defined by the standard NF Q34-020, said fibrous sheet comprising 10-70% of starch and at least 30% of papermaking fibers, based on the total weight of the dried fibrous sheet, wherein starch insoluble in water at the incorporation temperature is added to the fibrous sheet prior to the drying step of the fibrous sheet, said fibrous sheet is dried with a gradually increasing temperature such that the starch is fully gelatinized and made soluble, and said starch is substantially uniform throughout the thickness of said fibrous sheetEvenly distributed.

2. A fibrous sheet according to claim 1 comprising from 15 to 40% starch, based on the total weight of the dry fibrous sheet.

3. A fibrous sheet according to claim 2 comprising 20 to 35% starch, based on the total weight of the dry fibrous sheet.

4. A fiber sheet according to any one of claims 1 to 3, wherein the basis weight is in the range of 100 to 600g/m²In the meantime.

5. Fibrous sheet according to claim 4, wherein the basis weight is in the range of 130 to 400g/m²In the meantime.

6. Fibrous sheet according to any of claims 1 to 3, according to the application for 9 x 8cm²The NF Q34-020 standard for the sheet sample measured disintegration time in water of less than 50 seconds.

7. The fiber sheet according to claim 6, which is suitable for use in a range of 9 x 8cm²The NFQ34-020 standard for the sheet sample measured disintegration time in water of less than 35 seconds.

8. The fiber sheet according to claim 7, which is suitable for use in a range of 9 x 8cm²The NFQ34-020 standard for the sheet sample measured disintegration time in water of less than 15 seconds.

9. A fibrous sheet according to any of claims 1 to 3, wherein the loss of strength measured according to the bench test corresponds to the loss of strength of a sheet sample when forming an angle of at least 85 ° after wetting with water for 6 seconds, wherein the bench test comprises: the sample was laid flat and perpendicular to the edge, a portion of the sample, 10cm extending beyond the edge, the stage having a horizontal plane, a vertical plane and a straight prismatic stage at the intersection between the horizontal and vertical planes and the sample being rectangular, cut longitudinally to a width of 2.54cm and a length of 13cm,

the sample was wetted using an electroburette, the endpiece of which was placed 1cm above the test piece, 3ml of water was supplied within 6 seconds, the water was deposited in the center of the test piece above the edge, at which point the sample formed an angle to the horizontal,

the bend angle relative to the horizontal plane was recorded 6 seconds after the water was delivered.

10. The fiber sheet according to claim 9, wherein the loss of strength measured according to the bench test corresponds to the loss of strength of the sheet sample when an angle of 88 ° to 90 ° is formed after wetting with water for 6 seconds.

11. The fiber sheet according to any of claims 1-3, having a residual wet strength compared to its dry strength of less than 1% as determined according to the ring crush test, wherein the ring crush test comprises:

the samples were fixed as in standard ISO 12192: 2002, cut to a width of 15mm and a length of 152.4mm in the longitudinal direction, and tested in a wet state just before the measurement in immersion in water for a period of less than 2 seconds,

the sample is placed between the two plates,

the compressive force was applied at a rate of 10 mm/min,

the maximum resistance was recorded.

12. A fibrous sheet according to any of claims 1 to 3 comprising further additives selected from disinfectants, cleaning agents or fragrances which provide additional functions.

13. A method of manufacturing a fibrous sheet according to any of claims 1 to 12 having a disintegration time in water of less than 120 seconds comprising a step of preparing a pulp by suspending fibres in water, a step of forming a fibrous sheet from said pulp and a drying step, characterised by further comprising the steps of adding to the fibrous sheet starch insoluble in water at the incorporation temperature and drying the fibrous sheet containing starch at a temperature sufficient to gelatinise at least some of said starch prior to said drying step.

14. The method according to claim 13, said water-insoluble starch being incorporated into the pulp upstream of the forming table.

15. A process according to claim 13 or 14, incorporating a water-insoluble starch while the fibrous sheet is on the forming wire.

16. The method of claim 15, wherein the water-insoluble starch is sprayed onto the fibrous sheet while the fibrous sheet is on the forming wire.

17. A process according to claim 13 or 14, comprising a pressing step before the drying step.

18. The method according to claim 13 or 14, said water-insoluble starch being a starch modified by a physical, chemical or physico-chemical treatment.

19. Use of a combination of water-insoluble starch and water-soluble starch for the manufacture of a fibrous sheet according to any one of claims 1 to 12.

20. Process for the manufacture of a fibrous sheet according to one of claims 1 to 12 having a disintegration time in water of less than 120 seconds, characterized by the fact of comprising the following steps: suspending fibers in water, forming at least a first fiber layer and a second fiber layer from said fibers, depositing starch on the second fiber layer, depositing the first fiber layer on the second fiber layer, joining the two layers together into a fibrous sheet and drying the sheet.

21. A method according to claim 20, wherein the starch is deposited on the second layer in a dry state.

22. A method according to claim 20, wherein the starch is a combination of water soluble and water insoluble and is deposited on the second layer in a dry state.

23. A method according to claim 21 or 22, wherein the starch is deposited in powder form.

24. The method according to claim 20, wherein at least one third layer is formed and deposited on said two layers, whether or not starch is interposed.

25. The method according to one of claims 13-18 and 20-24, wherein the sheet is pressed before drying or calendered after drying to obtain a post-drying density of 450kg/m³To 650kg/m³The sheet in between.

26. Use of a fibre sheet according to one of claims 1 to 12 for the manufacture of a core for supporting a paper roll, one or more strips from said fibre sheet being spirally wound around a cylinder.

27. Core consisting of one or more helically wound strips, characterized in that said strips are fibrous sheets according to one of claims 1-12.

28. A toilet paper roll comprising a core according to claim 27.

29. Tampon applicator comprising a fibrous sheet according to one of claims 1 to 12.