RU2386424C2 - Method for making absorbing product - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: there is developed method for making an absorbent hygienic product containing a set of components which are interconnected during fabrication procedure. A cloth of the component, the component itself or its selected area contain thermochromic fibres designed to recolour between from contrasting colour to less contrasting colour. Recolouring of the thermochromic fibres is initiated during one operation of the fabrication procedure, and the presence of the contrasting thermochromic fibres are identified by a sensor. While controlling the procedure, some action is initiated in regard to the observed presence of the contrasting thermochromic fibres.

EFFECT: invention allows improving flexibility of the fabrication procedure control in making the product.

15 cl, 4 dwg

Description

Technical field

The present invention relates to a method for manufacturing an absorbent hygiene product, such as a diaper, diaper-panties, sanitary napkin, and an incontinence guard containing a plurality of components that are connected together during the process. In accordance with the invention, a method has been developed that provides advanced control of certain technological operations.

BACKGROUND OF THE INVENTION

Absorbent articles contain many components similar to roll materials forming the outer and inner covering sheets of the article, absorbent layers, etc., which are joined together, for example, by heat bonding, ultrasonic welding, or gluing in a high-speed process. Other components, such as elastic threads, fastening tabs, waist belts, side panels, belts, etc., can also be included in products like diapers, diaper-panties and protective devices used for incontinence. All these components must be superimposed and secured when the product is in the correct position. Cutting operations, in which selected pieces of materials are cut, also take place in the manufacture of absorbent products, and cutting must be performed at a precisely specified location. Managing and synchronizing the connection of various components in an absorbent product, laying the foundation on a selected area of the component, controlling the joint patterns resulting from heat bonding, welding or gluing, as well as controlling cutting operations are critical to product quality.

US-A-5045135 discloses a method for controlling alignment during cutting in a diaper making machine. The cloth for the manufacture of diapers, on which there are many absorbent spacers located at a certain distance from each other in the longitudinal direction, passes through the detection means determining the position of the edge of the spacer. The cutting means are controlled by signals from the detection means.

EP-A-1199057 discloses a method for manufacturing an absorbent article having a predetermined pattern element located at a predetermined location of the article. The patterned element is formed by printing on a continuously moving web material (web) fed at a selected speed, and cut into selected segments at predetermined locations. The position of the patterned element formed by printing is determined, and the signal is used to control the feed speed of the web, resulting in a patterned element formed by printing in the right place relative to the place of cutting.

In these two documents, the position of the edge of the gasket and the patterned element formed by printing, respectively, are visually determined and used to control certain technological operations. However, such product elements that can be visually detected in a specific place and which can be used to control the process are not always available, and therefore there is a need to increase the flexibility of process control.

Objective and most important features of the invention

The objective of the present invention is to provide a solution to the above problems and to create a more flexible system designed to control and synchronize certain technological operations in the manufacture of absorbent products.

These and additional tasks in accordance with the invention were achieved by incorporating thermochromic fibers into the canvas (canvas) of a component, component or its selected zone, wherein said thermochromic fibers are capable of changing color from a contrasting color to a less contrasting color; providing color changes of these thermochromic fibers during one operation of the process; determining the location of thermochromic fibers in a state in which their contrasting color can be detected by means of detection; performing some action (action) in response to the location of the dark fibers.

EFFECT: invention allows avoiding violation of synchronizing marks on the product and avoiding the need to cut off material on which there are synchronizing marks.

In one embodiment, a color change of the thermochromic fibers is provided before the detection operation, wherein the color of the thermochromic fibers will change to a contrasting color that can be detected by said detection means. Preferably, the color change is reversible and “disappears” after detection by said detection means.

In an alternative embodiment, the thermochromic fibers included in said article have a contrasting color that can be detected by said detection means, wherein a color change of the thermochromic fibers is provided after the detection operation. Preferably, the color change is irreversible and such that the thermochromic fibers become less contrasting with respect to the surrounding areas of the article.

In accordance with one aspect of the invention, data is transmitted from said detection means to controls for controlling a process operation and / or a process parameter, wherein said process step and / or process parameter is controlled in response to data transmitted from the detection means.

In accordance with an additional aspect, the position and / or configuration of the color detected zone created by the indicated thermochromic fibers is compared by means of said control means with a predetermined value and / or detected (determined) location of a component of said article, said control means providing control of one (- g) or several technological operations and / or technological parameters, when the position and / or configuration of the specified color detected zone deviates camping on the predetermined value and / or said detected location. Examples of such technological operations and / or process parameters are: temperature, the location of the component of the product and / or technological equipment, the speed of the process, the tension of the rolled material.

In accordance with one aspect of the invention, said color-detected region is a heat-bonded patterned element, a welded patterned element, an adhesive patterned element or the like, in which the bonding process has caused a color change in the bonded zones.

In one embodiment, the position of the color detected zone created by the indicated thermochromic fibers is used as a synchronization mark to connect two or more components of the product together in selected zones.

In a further embodiment, the position and / or configuration of the color-detected zone created by the indicated thermochromic fibers is compared by means of said control means to a predetermined value and / or detected (determined) location of a component of said product, and an alarm is generated when the position and / or the configuration of said color detected area deviates from said predetermined value and / or said detected location.

In accordance with another additional aspect of the invention, thermochromic fibers change color at a temperature of from 45 to 150 ° C, preferably from 50 to 130 ° C, more preferably from 50 to 120 ° C and most preferably from 60 to 120 ° C.

Brief Description of the Drawings

The invention will be described hereinafter in more detail by way of examples and with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of an absorbent article in the form of a diaper-panties.

Figure 2 is a plan view of a diaper-panties in its flat, unstretched condition before giving it a given shape when viewed from the side facing the body.

Figure 3 is a schematic perspective view of a portion of a production line for manufacturing a diaper-panties.

Figure 4 is a schematic view of a part of the production line located downstream.

Definitions

Absorbent product

The term “absorbent article” refers to articles that are placed on the skin of a carrier to absorb and retain body exudates, such as urine, feces, and menstrual fluid. The invention mainly relates to disposable absorbent articles, which are articles that are not intended to be washed or otherwise restored to their original condition, or reused as absorbent articles after use. The absorbent article contains many components that are connected together in the process, such as an internal liquid-permeable covering element, an external liquid-tight covering element, an absorbent structure, a receiving layer, elastic elements, fastening means, etc.

Inner liquid-permeable coating element

The inner liquid-permeable cover element forms the inner cover element of the absorbent article and, when used, is placed in direct contact with the skin of the wearer. The inner liquid-permeable coating element may comprise a non-woven material, for example, a non-woven material of a spunbond production method, a non-woven fabric obtained by melt aerodynamically, obtained by carding, hydro-entangling, laying in a wet state, etc. Suitable non-woven materials may consist of natural fibers, such as wood pulp or cotton fibers, artificial fibers such as polyester, polyethylene, polypropylene, viscose, etc., or a mixture of natural and artificial fibers. In addition, the material of the internal liquid-permeable coating element may consist of fiber tows that can be bonded to each other to form some kind of connection configuration, such as, for example, disclosed in EP-A-1035818. Additional examples of materials of the internal liquid-permeable covering element are porous plastics, plastic films with holes, laminates made of film / non-woven materials, etc. Materials suitable as materials of the internal liquid-permeable covering element must be soft and non-irritating to the skin and must quickly pass the fluid secreted by the body, such as urine or menstrual fluid. In addition, the internal liquid-permeable coating element may be different in different parts of the absorbent article.

External liquid impervious cover element

The outer liquid-impervious cover element forms the outer cover element of the absorbent article in at least its central zone. The outer liquid-impermeable coating element may comprise a thin plastic film, for example, a polyethylene or polypropylene film, a non-woven material coated with a liquid-impervious material, a hydrophobic non-woven material that prevents the penetration of liquids, or a laminate, for example, of a plastic film and non-woven material. The material of the outer liquid impervious cover element may be breathable so as to allow steam to escape from the absorbent structure while preventing the passage of liquids through it. Examples of breathable materials of external liquid-impermeable coating elements are porous polymer films, non-woven laminates from layers obtained by a spinneret production method and aerodynamic method from a melt, laminates from porous polymer films and non-woven materials.

Absorbent structure

An “absorbent structure” is an absorbent structure located between two coating elements of an absorbent article. The absorbent structure may be an absorbent structure of any conventional form. Examples of frequently occurring absorbent materials are fluff pulverized pulp, layers of tissue paper, highly absorbent polymers (so-called superabsorbents), absorbent foam materials, absorbent nonwoven materials, or the like. It is well known to combine fluff pulverized pulp with polymers with ultra-high absorption capacity in an absorption structure.

Typically, absorbent articles have absorbent structures containing layers with different properties in terms of liquid acceptability, liquid distribution ability, and retention capacity. Thin absorbent bodies, which are widely used, for example, in diapers for children and in incontinence protectors, often contain a compressed mixed or layered structure of fluff pulverized pulp and ultra-high absorbency polymers. The size and absorption capacity of the absorbent structure can be varied to suit different uses, such as for infants or for adults with incontinence.

Receiving layer

The so-called receiving layer may be located between the inner liquid-permeable covering element and the absorbent structure. The receiving layer is configured to quickly receive and temporarily hold the recovered liquid before it is absorbed by the absorbent structure located beneath it. Such receiving distribution layers are well known in the art and may consist of porous fiber wool or foam materials.

Fastening means

The fastening means are used to fasten the various components of the absorbent article together with the possibility of separation during use, for example, to fasten the front and rear parts of the diaper together to form a shape similar to the shape of underpants. The fastening means are usually in the form of mechanical fastening elements, such as fastening elements in the form of hooks and loops (Velcro®), or adhesive tapes.

Elastic elements

Elongated elastic elements are used on some products to improve the fit of the product in certain areas, such as leg openings and / or waist zone. Elastic elements, such as elastic threads, are attached to a layer of material or between layers of material. Alternatively, the elastic elements can be made of a material that is capable of translating it by some means, for example, heat, into an elastic state, while they can be attached to the product in an unstretched “inactive” state and subsequently transferred to a tightened elastic state.

Thermochromic pigments

Thermochromic pigments are organic compounds that change color in a reversible or irreversible manner when passing through a certain threshold temperature. Thermochromic pigment mainly contains three main components: (i) a coloring organic compound, which is an electron donor, (ii) a compound, which is an electron acceptor, and (iii) a solvent reaction medium that determines the temperature at which the staining reaction occurs.

A thermochromic powder material that can be used in accordance with the invention can be obtained from particles of a non-thermoplastic resin, comprising three components, which are a chromogenic electron donor substance, electron acceptor substance and solvent, by coating the particles with a high molecular weight hydrophilic compound. The thermochromic powder material, when incorporated into the polyvinyl chloride plastisol, remains free from the influence of a plasticizer, stabilizer, lubricant or the like contained in the plastisol, and retains very high stability even when heated.

The manufacturing process of a thermochromic polyvinyl chloride molded product is characterized by incorporating a thermochromic powder material into a polyvinyl chloride plastisol containing a vinyl chloride resin (polyvinyl chloride), a plasticizer, a stabilizer, a lubricant and a filler. After that, the resulting mixture is subjected to molding. A thermochromic powder material is obtained from particles of a non-thermoplastic resin into which three components have been encapsulated, which are a chromogenic electron donor substance, an electron acceptor substance and a solvent by coating the particles with a high molecular weight hydrophilic compound.

Thereby, a molded thermochromic polyvinyl chloride material can be made which is very likely to undergo a reversible color change with temperature. A material like this becomes surface colored when the temperature rises above about 40 ° C. The color change is reversible. This is further described in US Pat. No. 4,826,550.

Similar thermochromic pigments and a mechanism causing a temperature-induced color change are well known in the art and are described, for example, in US Pat. No. 4,826,550 and US Pat. No. 5,197,958.

Thermochromic or thermosensitive color-changing fibers are known from the textile industry as being used in clothing, sports equipment, etc. The fibers are either produced by interfering with the thermochromic pigment in the base resin from which the fibers were to be made, for example a polyolefin such as polyethylene or polypropylene, polyester, polyvinyl alcohol, etc., or by using a thermochromic dyeing liquid for fibers. The manufacture of heat-sensitive color-changing fibers is disclosed, for example, in JP 2002138322 and JP 2001123088. The fibers change color at a selected temperature. The color change is either reversible or irreversible.

An example of a fiber that can be used in accordance with the invention is a thermochromic fiber, which is partially characterized in that the flexural modulus of the base resin is in the range of 300 to 1500 MPa for a thermally sensitive color-changing fiber. The fiber is formed by melt-mixing the thermally color-dispersed pigment in a dispersed state in a base resin of a polyolefin resin and / or a polyolefin resin mixed with a thermoplastic resin. This fiber was previously used in the textile industry. It has been found that fibers with this characteristic may also be suitable for use in absorbent articles, especially diapers. The fiber is further described in JP 2002-138322.

In another embodiment, the thermochromic fiber is a thermosensitive color-changing, acrylic synthetic fiber. Such fibers can be formed from a variety of long fibers or short fibers from a heat-sensitive color-changing synthetic acrylic fiber having an outer diameter of elementary fiber of 1-100 microns. Fibers can be formed by dispersing 0.5-40 weight percent of a heat-sensitive pigment containing the three main ingredients, which are (A) a coloring organic compound representing an electron donor, (B) a compound representing an electron acceptor, and (C) chemically an active solvent that determines the temperature at which a staining reaction occurs between ingredients A and B. This is described in more detail in JP 2001-055623.

Another thermochromic fiber in accordance with the invention is a two-component fiber, which has the ability to very well reversibly change color, brightness and durability. It can be obtained by using (1) a thermally color-changing polyester consisting of a heat-color-changing material, a thermoplastic polyester, and (2) a fiber-forming polyester in which м 50 mole percent of the acid component is terephthalic acid; 0-50 molar percent of it is isophthalic acid and ≥70 molar percent of the diol component consists of butanediol and / or hexanediol, which are subjected to a process of forming bicomponent fibers in the melt. The resulting yarn is then pulled to obtain a given fiber, which is a two-component fiber containing a part consisting of component (1) connected to a part consisting of component (2) and having a fiber strength of ≥1.5 g / denier, a relative fiber elongation of ≤80% and a shrink coefficient of ≤25% in boiling water. This is further described in JP 4241115.

Another fiber that has very high friction life and excellent mechanical properties that may be suitable for the invention can be obtained by using a low melting thermoplastic resin containing a thermosensitive color-changing granular material as a core component and a high melting thermoplastic resin in as a component, which is a shell, with their specific ratio.

The fiber is obtained by mixing an acid developing agent (e.g., 3,3'-dimethoxyflurane) with an acidic substance (e.g., phenol) and a solvent (e.g., octyl alcohol), granulating the resulting mixture and spinning the bicomponent fiber from a thermoplastic resin (e.g. polypropylene) having a melting point of ≤230 ° C and containing 1-40 weight percent of the resulting color-sensitive color-changing granular substance. Granules are obtained having a grain diameter of 1-50 μm and a heat resistance of ≥200 ° C as a core component and a thermoplastic resin (e.g. nylon) having a melting point of ≤280 ° C in the quality of the composition representing the shell, with the weight ratio of the component representing the core and the component representing the shell, which is (1/9) - (9/1), while the fibers have a smooth surface and excellent mechanical characteristics at a high level vyp ying function color changes due to temperature sensitivity. This method is further described in JP 3161511.

The heat-sensitive pigment used in thermochromic fibers preferably has an average particle size of 0.5-50 microns, preferably 0.5-30.0 microns, even more preferably 0.5-15.0 microns, when measured in accordance with ASTDM method.

The heat-sensitive pigment may preferably be a microcapsule-type pigment, which is known in the field of heat-sensitive pigments.

Description of Preferred Embodiments

The panty diaper 1 disclosed in the drawings typically comprises a front zone 2, a rear zone 3, and a crotch zone 4 between the front zone and the rear zone. In its most common form, the diaper-panties comprises a liquid-permeable inner cover member 5, a liquid-impervious outer cover member 6, and an absorbent core 7 located between the inner and outer cover elements. The panty diaper is designed to cover the lower part of the body of the wearer like a pair of absorbing panties. The front and rear zones 2 and 3 may have a material composition different from the crotch zone, for example, only the crotch zone may contain liquid impermeable material.

The front and rear zones 2 and 3 are connected to each other along two opposite side edges, designated 2a, 3a, 2b, and 3b, respectively, to form a hole 8 for the waist and two holes 9 for the legs. The front and rear zones 2 and 3 are connected along the indicated side edges, respectively marked 2a, and 3a, and 2b, and 3b, for example, by means of glue, ultrasonic welding, heat sealing or the like with the formation of side seams 10. The front and rear zones 2 and 3 can be joined along their lateral edges so that the inner covering element 5 is turned inside at the side seams, as shown in the drawings. Alternatively, they are connected so as to overlap, with the inner covering element 5 of either the rear or the front zone facing the outer covering element 6 of the opposite zone.

The waist zone and at least part of the leg openings are elasticized. Elastification is usually carried out through a variety of elastic elements, such as elastic threads 11 and 12, attached with the possibility of pulling to a layer of material or between layers of materials. Elastication of the waist zone in accordance with the embodiment shown in the drawing is carried out by means of an elastic belt 13 containing a substantially inelastic non-woven material 14, which is elasticized by elongated elastic elements 11, such as elastic threads, which are secured with the possibility of pulling inside the belt 13.

The product has a longitudinal direction y and a transverse direction x.

The inner covering element 5 and the outer covering element 6 extend outwardly beyond the peripheral edges of the absorbent structure 7, and their inner surfaces are connected to each other, for example, by gluing or by heat welding or ultrasonic welding. In addition, the materials of the inner and outer coating elements can be attached, for example, by means of glue to the absorbent structure.

The absorbent articles in the form of a panty diaper shown in the drawings are only one example of an absorbent article for personal hygiene, and the invention can be applied to any type of absorbent article falling within the definition given above, including so-called open diapers in which the front and the back are fastened together by fastening elements, such as adhesive tape or fastening elements such as hooks and loops, diapers with a belt, in which the belt elements are used for fastening the product around the waist of the wearer, incontinence pads, sanitary napkins and panty liners intended for everyday use, to be worn in wearer's panties, etc.

An absorbent article in accordance with the present invention contains thermochromic fibers. As mentioned above, thermochromic fibers are fibers having a thermochromic pigment incorporated therein. Thermochromic pigment mainly contains three main components, namely (i) a coloring organic compound, which is an electron donor, (ii) a compound, which is an electron acceptor, and (iii) a solvent reaction medium that determines the temperature at which the staining reaction occurs.

Similar thermochromic pigments and a mechanism for triggering a temperature-induced color change are well known in the art and are described, for example, in US Pat. No. 4,826,550 and US Pat. No. 5,197,958. In the first-mentioned document, polyvinyl chloride molded articles having incorporated therein are disclosed. thermochromic powdery material. In the document mentioned last, a diaper with a moisture indication is disclosed having a thermochromic dye applied by printing onto the back sheet of the diaper.

A description of fibers having similar thermochromic pigments included therein can be found in any of the following published Japanese patent applications: JP 2002-138322, which discloses thermally color-changing fibers for various textile applications, such as wool-like materials; JP 2001-123088, which discloses a reversibly thermochromic coloring liquid for fibers and materials made from them; JP 2001-055623, in which thermosensitive color-changing synthetic acrylic fibers are disclosed; and JP 8027653, which discloses a thermally color-changing, non-woven material containing a certain amount of reversibly color-changing crimped fibers.

Thermochromic pigment can be introduced into the base resin of the fibers in the form of microcapsules or in the form of a coloring liquid for the fibers.

The entire fiber can be dyed with a thermochromic pigment or the fiber can be a bicomponent fiber, with either the core or the outer sheath of the fiber provided with the thermochromic pigment. The color change can be either reversible or irreversible.

In accordance with the invention, thermochromic fibers are used in the process as an indicator and / or synchronization tag in one or more technological operations. One goal may be to control one or more process operations and / or to control one or more process parameters. Another goal may be to generate an error or alarm when the detected value deviates from the set value, which indicates that there is something in the process that needs to be adjusted. Below will be described an example of parts of a process for manufacturing a diaper-panties in accordance with the embodiment shown in figures 1 and 2. It will show how thermochromic fibers can be used to control certain technological operations.

Thermochromic fibers, depending on the intended purpose, can be included in any appropriate component of the absorbent product, such as an outer covering layer, an absorbing structure, an absorbing structure layer, an internal liquid permeable layer, a covering element, fastening tabs, elastic elements, etc. Alternatively, thermochromic fibers can be applied, for example by spraying, to a component of an absorbent article during a process.

The properties of thermochromic fibers that characterize the color change can be such that the fibers, when a certain temperature (initiation temperature) is exceeded, change from “colorless” or “slightly dyed” fibers to fibers with a color that contrasts with the surrounding material. In this case, the color change can be caused by a technological operation, for example, calendering during heating, thermal bonding, welding, applying hot glue, etc. Preferably, the color change is reversible, so that after a period of time, the fibers return to their less contrasting color and will be invisible or at least not so clearly visible on the finished product.

Alternatively, the color-changing properties of thermochromic fibers are such that, when introduced into a component of an absorbent article, they have a contrasting color. When exposed to temperatures above the “initiation” temperature, they will change color to a less contrasting color or even become colorless. This “initiation” temperature may also be due to a process step as described above. However, in this case, the detection of thermochromic fibers should occur before the operation of determination (detection). The “initiation” temperature may be the same as above. In this case, the color change should be irreversible.

The diaper panties can be manufactured by a process, the parts of which are illustrated in FIGS. 3 and 4. The various components of the absorbent article are connected on a (not shown) belt conveyor moving in the direction of travel indicated by arrow A. Two continuous pieces of essentially non-elastic web material 14, intended for the formation of the belt 13, are fed in parallel and being located at a selected distance from each other along the belt conveyor. Belt roll materials 14 have two longitudinal side edges 14a and b and are joined together with their longitudinal edges 14a facing each other with a continuous piece of material 15 of the mill, intended to form the front, back and crotch zones 2, 3 and 4 of the product. The material 15 of the mill contains the inner and outer covering elements 5 and 6 having absorbing structures 7 enclosed between them in spaced places.

The material 15 of the mill has two longitudinal side edges 15a and b and is supplied together with the rolled web material 14 of the belt, and they are joined by gluing, ultrasonic welding 16, or the like, providing overlap so that their respective longitudinal side edges overlap at least approximately by 5 mm.

A plurality of elongated elastic members 12 are then fed and joined to each of the rolled web materials 14 of the belt in any suitable manner known in the art, for example by gluing 17. The elongated elastic members 12 are fed under a selected tension, or alternatively, they can be fed substantially not strained and subsequently can be "activated" to a strained state, for example, by heating. In the latter case, the elongated elastic elements 12 are a certain type of elastomeric material, called heat-elasticizing material.

After the elongated elastic elements 14 are fed to the roll web materials 14, said roll materials each pass through a folding roll 18, which continuously bends the corresponding roll web material 14 of the belt across to the feed direction A along the fold line 19 and over the elongated elastic elements 12. The free longitudinal edge 14b of each roll material 14 of the belt is subsequently attached to the corresponding material 15 of the mill to its longitudinal edge 15A with the provision of overlapping on its opposite side, like the other longitudinal ny edge 14a of the belt roll material that has already been attached to the web material 15 mill. Alternatively, both side edges 14a and b of the web roll material 14 are attached to the same side of the web roll material 15. The overlapping edges of the web materials 14 and 15 are joined by ultrasonic welding or the like using a device designated 20.

The "effect" of the connection, for example, obtained by ultrasonic welding, the seam provided by the second connecting device 20, can be significantly stronger (stronger) than the effect of the connection provided by the first connecting device 16, which can only form, for example, a weak tack weld, sufficient to hold the overlapping edges of the two roll materials 14 and 15 together until the next joining station 19. The folded web material 14 of the belt, together with the elongated elastic elements 11 enclosed therein, will form the elastic belt 13 of the absorbent article.

As an alternative to bending the rolled web material 14 of the belt, the additional web material of the belt can be fed and attached so as to overlap the longitudinal edge 14 a of the web material 15 of the mill. The free lateral edges of two inelastic web materials are connected to each other either in a previous or subsequent operation. In this case, each of the web materials 14 of the belt has a width corresponding to the width of the belt 13.

It should be understood that various technological operations of joining various sheets of material (roll materials) can be performed in any order. Similarly, the invention is applicable to production in which the products are oriented in the transverse direction, as shown in FIG. 3, and also for production in which the products are oriented in the length direction on the production line.

Additional components, such as elongated elastic elements forming leg gums 12, are attached to the web to be treated by an appropriate method known in the art. Holes 21 for the legs are cut out in the canvas to be treated, and the diaper-panties are formed by folding twice the fabric to be processed by folding with the fold 22 of the fabric to be processed, connecting the bent fabric to be processed, for example, by ultrasonic welding using the device indicated at 23, periodically across to the feed direction from the waist hole to the leg holes for the formation of side seams 10 and subsequent cutting by means of a cutting device 24 along Shackle seams to form individual articles 1 in the form of pants. This is illustrated in FIG.

The presence of thermochromic fibers included in the inner and / or outer covering elements 5 and 6, or between the inner and outer covering elements 5 and 6, and / or in the material 13 of the belt, will lead to a color change of these fibers, initiated by ultrasonic welding. This will lead to the formation of patterns 25 and 26 obtained by welding, which contrasts with the surrounding parts of the fabric material and, thus, can be easily detected. In the embodiment illustrated in FIGS. 3 and 4, welding patterns 25 and 26 are formed in the waist zone and at the side seams 10. These welding patterns are detected by image recording means 27 and 27, for example, in the form of so-called a video monitoring system, which is an automatic monitoring system, for example, supplied by Novotek Sverige AB. An image of the pattern obtained by welding in the weld zone is formed, which leads to the formation of a video signal, which is supplied to the digital encoding and image analysis device 29 and 30, respectively, comparing the recorded image with a predetermined range of values. If the recorded image deviates from a predetermined range of values (set value), a signal is supplied to the correction and control device, designated 31, 32 and / or 33, respectively, which may have one or more of the following functions:

a) control of ultrasonic welding devices, for example, in relation to energy consumption, positioning of the device, etc .;

b) positioning control, regulation of web speed and / or web tension of roll materials introduced into the ultrasonic welding device;

c) controlling the cutting device 24 and synchronizing the cutting device 24 depending on the location of the welded pattern;

d) generating an alarm 34, 35 to indicate that measures should be taken to control the process.

In the case mentioned last, the measures can be a check whether the equipment, for example, the console of the ultrasonic welding machine, is worn out and whether it is necessary to replace it, or whether it is necessary to adjust one or more technological operations or one or more process parameters, such like temperature, web speed, web tension, location of equipment or roll materials.

The position of the weld can also be controlled relative to a fixed point on the roll material, for example, on the edge contour of the absorbent structure 7, which can also be detected by the image recording means 28.

The example shown and described in connection with FIGS. 3 and 4 only illustrates one embodiment of the invention. It should be understood that the principle of using thermochromic fibers according to the present invention in controlling the manufacturing process of absorbent articles can be modified in many different ways. Some additional examples are given below:

- synchronization tags, for example, for attaching a component, such as a fastening tab, in a specific place on another component;

- detection of a pattern (patterned element) formed by glue and created by applying hot glue to the rolled material;

- detection of the pattern formed by thermal bonding and created by means of a heated roller, causing the melting of at least part of the components of the roll material;

- detection of a cut in the roll material;

- detecting de-elasticized portions of an elastic component, such as an elastic non-woven material, a laminate of non-woven material and a film, or a non-woven laminate, in which de-elastification in selected areas was performed by heat treatment, ultrasonic welding, or the like.

In some of the above examples, a process step prior to the detection device may cause a temperature increase to initiate a color change of the thermochromic fibers. In other examples, thermochromic fibers can be used that initially have a contrasting color.

In some cases, the configuration of the entire defined area, such as a pattern obtained by welding containing thermochromic fibers having a contrasting color, is detected by the image recording apparatus as described above. In other cases, only the presence of a zone containing contrasting thermochromic fibers or a contrast line between the zone containing contrasting thermochromic fibers and the adjacent zone is detected. In such cases, a simpler sensor may be used instead of an image recording device.

In the case where fibers are used that must change color before detection, the reaction time of the thermochromic fibers, that is, the time required for the color to change, and to pass from the moment the fibers are exposed to the initiation temperature, should be short enough to ensure detection capabilities by means of an image recording device or sensor, or, in other words, the distance between process equipment initiating a color change, for example, a welding device , a thermal bonding or gluing device, and an image recording means or sensor should be large enough to be detectable. Preferably, the reaction time is less than 3 seconds, preferably less than 2 seconds, and more preferably less than 1 second from the moment the fibers are exposed to the initiation temperature. A high temperature (significantly higher than the initiation temperature) acting on thermochromic fibers will provide a faster color change than a low acting temperature (close to the initiation temperature).

Changing the color to a contrasting color is preferably reversible, so that after a certain period of time, the fibers return to their original colorless state, or at least a less contrasting color, so that they will be more or less invisible in the final product. The return time should be long enough to allow detection, or, in other words, the distance between the process equipment initiating the color change, for example, a welding device, and the image recording means or sensor should be short enough so that the color change is retained by the detection device.

For applications in which it is desirable to preserve the color change of thermochromic fibers in the final product, for example, to constantly visualize the bonding pattern, thermochromic fibers with irreversible color change can be used.

As mentioned above, in an alternative embodiment, thermochromic fibers that initially have a contrasting color can be used. After they are used as, for example, synchronization marks or means for controlling a process, a color change is initiated by a heating operation, so that they change to colorless or at least fibers with a less contrasting color.

Thermochromic fibers can be incorporated substantially uniformly throughout the layer and mixed with other fibers in the layer. Alternatively, they are included only in selected portions of the layer. An additional alternative is that a separate fibrous layer, for example, a layer of nonwoven material formed mainly (at least 50%) or even completely of thermochromic fibers as the only fibrous component, is included in the product. An appropriate amount of thermochromic fibers, for example, in the inner cover sheet, the receive layer, the absorbent structure or the layer in the absorbent structure or in the outer cover sheet is at least 1 weight percent, preferably at least 5 weight percent, more preferably at least 10 weight percent and most preferably from 20 to 70 weight percent of the weight of said fibrous layer in zones in which said thermochromic fibers are distributed. Thus, if thermochromic fibers are distributed only in half of the layer, (concentration) in weight percent should be determined based on the weight (mass) of this half of the layer.

The remaining fibers with which the thermochromic fibers are mixed may vary depending on which component of the absorbent article thermochromic fibers are included in, for example, if it is a backsheet material covering a sheet, backsheet or absorbent structure. Thus, the remaining fibers can be cellulose fibers, polyethylene, polypropylene, polyester, polylactide, viscose fibers and the like. In one embodiment, the remaining fibers with which the thermochromic fibers are mixed are made of the same polymeric material as the thermochromic fibers. Thus, if thermochromic fibers are polypropylene fibers having a thermochromic pigment included therein, these thermochromic fibers can be mixed with other polypropylene fibers in which there is no thermochromic pigment.

In the case where a fibrous layer consisting of thermochromic fibers is used as the sole fibrous component, such a layer should have a density of at least 7, preferably at least 10 and more preferably at least 15 g / m ² .

As mentioned above, in an alternative embodiment, thermochromic fibers can be deposited, for example by spraying, on a component of an absorbent article during a process.

Two or more types of thermochromic fibers can be used in the same product. These different thermochromic fibers can have different colors and / or different initiation temperatures.

The time it takes for a color change to occur can be important, at least for some applications. For example, it may be desirable for a temperature change to occur in less than 3 seconds, preferably less than 2 seconds, and more preferably less than 1 second after the fibers are exposed to the initiation temperature. A high temperature (significantly higher than the initiation temperature) acting on thermochromic fibers will provide a faster color change than a low acting temperature (close to the initiation temperature).

Thermochromic fibers are preferably colorless or have the same color as the surrounding material, that is, do not contrast with the surrounding material, at a temperature that is below a certain temperature, preferably above normal indoor temperatures, during transportation and storage, and also lower than temperatures which products are exposed during manufacturing, with the exception of the initiation operation. When a certain temperature threshold value is crossed, thermochromic fibers change color and become visible and contrast with the surrounding material. This threshold temperature should be slightly lower than the temperature to which the components are exposed during the initiation process. “Slightly lower” in this context means at least 10 ° C, preferably 10-30 ° C lower than the indicated temperature to which the components are exposed during the initiation operation.

The corresponding threshold temperature may be in the range from 45 to 150 ° C, preferably from 50 to 130 ° C, more preferably from 50 to 120 ° C and most preferably from 60 to 120 ° C. As described above, the choice of the solvent reaction medium of the thermochromic pigment determines the temperature at which the staining reaction occurs. This is described, for example, in US Pat. No. 4,826,550 and US Pat. No. 5,197,958.

It should be pointed out that the present invention is not limited to the embodiments described above and shown in the drawings, but many modifications are possible within the scope of the claims.

Claims (15)

1. A method of manufacturing an absorbent hygiene product, such as a diaper, a diaper-panties, a sanitary towel, an incontinence guard, comprising a plurality of components that are connected together during the process, including the following operations:
a) introducing in this process thermochromic fibers into the web of a component, component or zone thereof, wherein said thermochromic fibers are capable of changing color from a contrasting color to a less contrasting color relative to the surrounding parts of the product;
b) providing a color change of thermochromic fibers during a single process operation;
c) determining by means of means (27, 28) for detecting the presence of thermochromic fibers in a state in which their contrasting color can be detected;
d) process control in response to the presence of thermochromic fibers in their state with a contrasting color. 2. The method according to claim 1, characterized in that the color change of the thermochromic fibers is provided before the determination operation, while the color of the thermochromic fibers will be changed to contrasting, which can be determined by the detection means (27, 28). 3. The method according to claim 2, characterized in that the color change is reversible and will disappear after determination by means of detection means (27, 28). 4. The method according to claim 1, characterized in that the thermochromic fibers included in the specified product have a contrasting color, which can be determined by the detection means (27, 28), and the color change of the thermochromic fibers is provided after the determination operation. 5. The method according to claim 4, characterized in that the color change is irreversible and such that the thermochromic fibers become less contrasting with respect to the surrounding areas of the product. 6. The method according to claim 1, characterized in that the data is transmitted from the detection means (27, 28) to the control means (29, 30) for controlling the technological operation and / or process parameter, while controlling said technological operation and / or parameter the process is carried out in response to data transmitted from the detection means. 7. The method according to claim 1, characterized in that the position and / or configuration of the color detected zone (25, 26) created by thermochromic fibers is compared by means of control means (29, 30) with a predetermined value and / or a specific location of a component of said products, while the controls provide regulation of one (or more) or more technological operations and / or technological parameters, when the position and / or configuration of the color detected zone deviates from a predetermined value and / or a certain location zheniya. 8. The method according to claim 7, characterized in that the color zone detected is a patterned element obtained by heat bonding, a patterned element (25, 26) obtained by welding, an adhesive patterned element in which the bonding process caused a color change in the bonded areas. 9. The method according to claim 7 or 8, characterized in that the selected technological operations and / or process parameters, including temperature, the location of the component of the product and / or technological equipment, the speed of the process, the tension of the rolled material. 10. The method according to claim 1, characterized in that the position of the color detected zone (25, 26) created by means of thermochromic fibers is used as a synchronization mark for connecting two or more components of the product together in selected zones. 11. The method according to claim 1, characterized in that the position and / or configuration of the color detected area (25, 26) created by thermochromic fibers is compared by means of control means (29, 30) with a predetermined value and / or a specific location of a component of said products and an alarm (34, 35) are generated when the position and / or configuration of the color detected zone deviates from the set value and / or the detected location. 12. The method according to claim 1, characterized in that the thermochromic fibers change color at a temperature of from 45 to 150 ° C. 13. The method according to claim 1, characterized in that thermochromic fibers change color at a temperature of from 50 to 130 ° C. 14. The method according to claim 1, characterized in that the thermochromic fibers change color at a temperature of from 50 to 120 ° C. 15. The method according to claim 1, characterized in that the thermochromic fibers change color at a temperature of 60 to 120 ° C.

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