DK169843B1

DK169843B1 -

Info

Publication number: DK169843B1
Application number: DK002794A
Authority: DK
Inventors: John Hardy Mosgaard Christensen; Helmut Erwin Schilkowski
Original assignee: Scan-Web I/S
Priority date: 1994-01-07
Filing date: 1994-01-07
Publication date: 1995-03-13
Also published as: DE69503758T2; ES2120717T3; DE69503758D1; EP0743995B1; WO1995018886A1; FI962761A0; ATE169074T1; JPH09510753A; FI111867B; AU1311395A; DK2794A; DK0743995T3; AU705139B2; CA2180534C; EP0743995A1; CA2180534A1; FI962761A; JP3802926B2

Abstract

For the manufacturing of dry-formed webs of cellulose fibres there are two different ways of binding the fibres, viz. an application of glue to the web surfaces and, respectively, an admixing into the fibre charge of heat actuated binding fibres that are actuated by passing the web through a heating zone. The latter method is the better in practice, of course, in particular for liquid absorbing products, but the problem exists that the finished material is dusting with short, unbonded fibres. According to the invention it has been realized that it is possible to widely avoid this problem by auxiliary use of the first method, modified to the effect that both surfaces of the web are concurrently subjected to a supply of a very small amount of glue in foamed condition, e.g. with only 1 gram per square meter, whereby the surfaces remain permeable, but also sealing against extrusion of short fibres from inside the web.

Description

DK 169843 B1DK 169843 B1

Den foreliggende opfindelse angår en fremgangsmåde til fremstilling af et tørformet fiberflor materiale baseret på tøroplagte cellulosefibre med en egnet sammen binding. Oplægningen af fibrene til dannelse af en løb-5 ende bane sker sædvanligvis ved, at et pulpmateriale defibreres og tilføjes i en luftstrøm, som fører de løse fibre til et fordelerhoved oven over en løbende, perforeret formewire, hvorunder der er anbragt en sugekasse til nedsugning af fibrene mod wiren, hvor de løbende 10 afsættes som et sammenhængende flor med ønsket banetykkelse. Produkterne udnyttes typisk som væskeabsorberende ark.The present invention relates to a process for producing a dry-formed fibrous material based on dry-laid cellulose fibers with a suitable bonding bond. The laying of the fibers to form a continuous web is usually accomplished by defibrating and adding a pulp material into an air stream which leads the loose fibers to a distributor head over a continuous, perforated molding wire, under which a suction box is provided for suction of the fibers towards the wire, where the continuous 10 is deposited as a continuous web of desired web thickness. The products are typically utilized as liquid absorbent sheets.

Det er vigtigt, at det oplagte flor stabiliseres eller sammenbindes, og i praksis opnås dette ved to 15 forskellige metoder, nemlig ved limning eller ved brug af bindefibre: 1. Limning: Floret føres på en bærewire forbi en limstation, hvori der fra et antal dyser sprøjtes et passende limstof, normalt af latextypen, på floret, 20 hvorefter wiren føres igennem en ovntunnel for udtørring af limen. Derefter overføres floret på en overliggende wire, mod hvilken det fastholdes ved sug oppefra, således at florbanens underside blotlægges, og floret føres så gennem eller over en anden limstation, hvor lim til-25 svarende sprøjtes mod denne underside. Floret føres derefter videre gennem en yderligere ovntunnel for slut-hærdning af limen, hvorefter floret er selvbærende og kan føres til oprulning og aflevering til lager eller til udlevering.It is important that the obvious web is stabilized or bonded, and in practice this is achieved by two 15 different methods, namely by bonding or by using binder fibers: 1. Bonding: The flower is passed on a support wire past a bonding station in which a number of nozzles, an appropriate adhesive, usually of the latex type, is sprayed onto the floor, after which the wire is passed through an oven tunnel for drying the adhesive. Then, the web is transferred to an overhead wire against which it is held by suction from above, exposing the underside of the web, and the web is then passed through or over another adhesive station where glue correspondingly is sprayed onto this underside. The floret is then passed through an additional oven tunnel for final curing of the glue, after which the flake is self-supporting and can be led to roll-up and delivery to storage or for delivery.

30 Ved denne metode kan fremstilles banevarer af gan ske høj kvalitet, men metoden er anlægsmæssigt krævende og sårbar overfor optrædende uregelmæssigheder i limstationerne. Desuden er det en begrænsning, at metoden ikke egner sig til tykkere banevarer, da det er vanskeligt at 35 opnå en stor indtrængningsdybde af limen, hvorved et forholdsvis tykt lag tenderer til at separere i midter- DK 169843 B1 2 .« planet, hvor bindingen er svag eller helt mangler. Produkterne vil typisk indeholde ca. 85% cellulosefibre og ca. 15% bindemiddel. Typiske produktvægte kan være 50-120 g/m2, idet tungere produkter let delaminerer.30 This method can produce high quality web products, but the method is demanding and vulnerable to irregularities occurring in the glue stations. Furthermore, it is a limitation that the method is not suitable for thicker web products, since it is difficult to obtain a large depth of penetration of the glue, whereby a relatively thick layer tends to separate in the middle. is weak or completely missing. The products will typically contain approx. 85% cellulose fibers and approx. 15% binder. Typical product weights can be 50-120 g / m2, with heavier products easily delaminating.

5 Ydermere er produkterne dårligt egnede til at indeholde superabsorbenter.Furthermore, the products are poorly suited to contain superabsorbents.

2. Brug af bindefibre: Ved denne fremgangsmåde frembringes en homogen indblanding af varmeklæbende bindefibre i cellulosefibrene, hvorved det udlagte fi-10 berflor kan fikseres alene ved at føres gennem en varme-zone. Dette er en både anlægs- og styringsmæssigt enklere metode, ved hvilken der kan fremstilles også tykke baner, da bindefibrene vil være ligeligt til stede både i de ydre og de indre lag i materialet. Produktvægten 15 kan typisk være 40-800 g/m2, og der kan benyttes en betydelig indblanding af superabsorberende stoffer eller andre additiver. Den opnåelige kvalitet er fuldt i orden til mange forskellige anvendelser, men der optræder dog visse ulemper ved, at man af naturlige grunde må begræn-20 se indblandingsprocenten af formstoffibrene, typisk til ca. 15 procent. Normalt rangerer cellulosefibrene i længde mellem ca. 0,5 og ca. 5 mm, medens formstoffibrene kan være noget længere. I praksis giver dette en udmærket binding af de længste cellulosefibre, hvorimod 25 de helt korte cellulosefibre bindes ufuldstændigt. Dette betyder, at materialet kan støve med korte fibre, hvilket ved visse anvendelser er uacceptabelt, og produkterne benyttes derfor overvejende som indlægsmaterialer i ydre omslag.2. Use of binder fibers: In this method, a homogeneous admixture of heat-sticking binder fibers is produced in the cellulose fibers, whereby the laid fiber floor can be fixed by passing through a heating zone only. This is a simpler method for both construction and control, by which thick webs can also be made, as the binder fibers will be equally present in both the outer and inner layers of the material. Typically, the product weight 15 may be 40-800 g / m2 and a considerable admixture of superabsorbents or other additives may be used. The attainable quality is fully acceptable for many different applications, but there are, however, certain disadvantages that, for natural reasons, it is necessary to limit the admixing percentage of the resin fibers, typically to approx. 15 percent. Normally, the cellulose fibers range in length between approx. 0.5 and approx. 5 mm, while the plastic fibers may be somewhat longer. In practice, this provides an excellent bonding of the longest cellulose fibers, whereas the very short cellulose fibers are incompletely bonded. This means that the material can be dusted with short fibers, which in some applications is unacceptable, and therefore the products are used predominantly as outer wrapping materials.

30 Ved opfindelsen ønskes den nævnte fiberstøvning imødegået, hvorved der naturligt kan spekuleres i en højere indblandingsgrad af binderfibre med forskellige længder. Dette er dog næppe nogen realistisk mulighed, * og ved opfindelsen er det erkendt, at en bedre løsning 35 vil være en kombineret anvendelse af de to nævnte frem- # gangsmåder, dog med limningsmetoden i modificeret form.In accordance with the invention, the said fiber dust is desired to be countered, whereby a higher degree of mixing of binder fibers of different lengths can naturally be speculated. However, this is hardly a realistic possibility, and it has been recognized by the invention that a better solution 35 would be a combined application of the two aforementioned methods, however, with the sizing method in modified form.

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Som nævnt opnås ved limningsmetoden et bindingsresultat, som vil være bedst ved baneoverfladen og dårligst ved midterlaget af banen, men for så vidt det ved kombineret anvendelse af de varmeklæbende bindefibre kun 5 drejer sig om at spærre mod støvning fra banen vil dette være opnåeligt ved at belægge banen med ganske tynde overfladelag af limstof. Da kohærensen i banematerialet vil være sikret ved aktiveringen af de varmeklæbende bindefibre vil en overfladelimning kunne udføres samti-10 digt på begge sider af den allerede selvbærende bane, og begge de tilførte limlag, som hvert især kan være ekstremt tynde, vil kunne hærdes ved gennemløb af en enkelt ekstra varmezone med relativt lav kapacitet. Når overfladerne af banematerialet således optræder med 15 tynde limbindinger vil der være spærret mod udtrængning af de korte cellulosefibre fra banematerialet, og dette er præcis det ønskede resultat. Ved opfindelsen skal der dermed ikke spekuleres i nogen forøget lokalbinding af disse fibre, omend virkningen tildels kan bero på, at 20 der netop optræder øgede fiberbindinger i overfladen, medens der i mindre grad er tale om en egentlig belægning af overfladen.As mentioned, the bonding method achieves a bonding result which will be best at the web surface and worst at the middle layer of the web, but insofar as the combined use of the heat-adhesive binder fibers is only about blocking dust from the web, this will be achievable by coat the web with quite thin surface layers of glue. Since the coherence of the web material will be ensured by the activation of the heat-sticky binder fibers, a surface sizing can be performed simultaneously on both sides of the already self-supporting web, and both of the applied adhesive layers, each of which may be extremely thin, can be cured by passage. of a single additional heat zone with relatively low capacity. Thus, when the surfaces of the web material appear with 15 thin adhesive bonds, the short cellulosic fibers from the web material will be blocked and this is exactly the desired result. In this invention, therefore, no increased local bonding of these fibers is to be speculated, although the effect may be due in part to the fact that increased fiber bonds have just occurred in the surface, while there is less actual coating of the surface.

Det er således et overordnet træk ved opfindelsen, at der til fiberbindingen gøres brug af de indblandede 25 varmeklæbende bindefibre, medens baneoverfladerne tætnes i større eller mindre grad ved påføring af limstof i beskeden mængde, uden ambitioner om nogen dyb indtrængning af limen i materialet. Det er herved ikke afgørende, hvorledes limtilførslen foregår, men det er 30 dog for opfindelsen et væsentligt detailaspekt at angive, hvorledes den kan foregå på en ny og særdeles sparsom måde for opnåelse af det ønskede resultat.Thus, it is an overall feature of the invention that the fiber bonding is made use of the blended heat-adhesive binder fibers, while the web surfaces are sealed to a greater or lesser extent by the application of a small amount of glue, with no ambition of any deep penetration of the glue into the material. It is thus not crucial how the adhesive application is carried out, but it is nevertheless important for the invention to indicate how it can be carried out in a new and very economical way to achieve the desired result.

Det er nemlig ved opfindelsen en foretrukket mulighed, at limstoffet tilføres i en opskummet form, hvorved 35 det kan virke fladedækkende med et minimum af tørstofindhold. Der er observeret den virkning, at væsken i det 4 DK 169843 B1In fact, it is a preferred option of the invention for the adhesive to be applied in a foamed form whereby it can act as a surface covering with a minimum of dry matter content. The effect has been observed that the liquid in it

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faldende skum fortrinsvis sætter sig som småklatter i krydsningsområderne mellem fibrene fremfor ved generel aflejring på fiberoverfladerne, og denne effekt er optimal for det ønskede resultat, nemlig at der med brug 3 af små mængder af både væske og tørstof kan skabes en binding af de korte fibre i overfladen, således at disse dels forbliver hvor de er og dels medvirker til at spærre mod udtrængning af de korte fibre fra det indre af banematerialet. Dette forbliver let og porøst, således 1 0 at det f.eks. vil være egnet til imprægnerede fugtservietter .falling foam preferably settles as small dots in the intersecting areas of the fibers rather than by general deposition on the fiber surfaces, and this effect is optimal for the desired result, namely that with the use of 3 small quantities of both liquid and dry matter a bonding of the short fibers can be created. in the surface so that they partly remain where they are and partly help to block the extrusion of the short fibers from the interior of the web material. This remains light and porous, so that e.g. will be suitable for impregnated wipes.

En udmærket virkning kan opnås ved tilførsel af blot 1-2 g binder pr. m2, idet der kan benyttes en vand-dispergeret forskummet binder med kun ca. 3 g tørstof 15 pr. liter. Skummet kan dannes i en konventionel opskum-ningsenhed, og i det opskummede volumen kan så limen være til stede i en mængde på blot ca. 0,3%. Tilsvarende vil det være ganske lidt vand, der skal udtørres fra produktet, hvorved tørringen og hærdningen af limen kan 20 ske med et ret lavt energiforbrug i den efterkoblede hærdezone.An excellent effect can be achieved by the application of just 1-2 g of binder per minute. a water-dispersed foamed binder with only approx. 3 g dry matter 15 per liter. The foam can be formed in a conventional foam unit, and in the foamed volume, the adhesive may then be present in an amount of just 0.3%. Similarly, quite a bit of water will need to be dried from the product, whereby the drying and curing of the glue can be done with a rather low energy consumption in the post-cured curing zone.

Påføringen af skummet kan ske på enhver egnet måde, eksempelvis ved lodret eller skrå nedføring af banen gennem et valsepar, med kontrolleret skumtilførsel til 25 valsegabet på begge sider af banen. En valsning af banen giver et attraktivt resultat derved, at overfladefibrene bindes i nedlagte stillinger, hvorved overfladen får en mere glat, fast og fast karakter.The application of the foam can be effected in any suitable manner, for example by vertical or inclined downward passage of the web through a roller pair, with controlled foam supply to the roller gap on both sides of the web. Rolling of the web gives an attractive result in that the surface fibers are bonded in closed positions, giving the surface a more smooth, firm and firm character.

Ved hjælp af tilsatte befugtningsmidler er det 30 muligt at styre indtrængningsdybden af den forskummede binder. Hvis indtrængningsdybden er for lille vil det tynde binderlag i overfladen hurtigt afslides, og hvis dybden er for stor vil dette dels indebære et unødigt > stort binderforbrug og dels give produktet en plastagtig 35 karakter, med træg vandoptagelse. .By means of added wetting agents it is possible to control the penetration depth of the foamed binder. If the penetration depth is too small, the thin bonding layer in the surface will quickly wear off, and if the depth is too large, this will involve an unnecessary> large binder consumption and partly give the product a plastic-like character, with sluggish water absorption. .

Principielt er det for opfindelsen ikke nogen be- DK 169843 B1 5 tingelse, at overfladelimningen udføres efter at den termisk styrede binding er aktiveret, da den ligeså godt kunne udføres før eller endda samtidigt med den termiske aktivering. Det er blot en betydelig praktisk fordel, at 5 limbelægningen på overfladerne tilføres efter at florbanen er stabiliseret ved den termisk betingede binding.In principle, for the invention it is not a condition that the surface sizing is performed after the thermally controlled bond is activated, as it could as well be performed before or even simultaneously with the thermal activation. It is only a significant practical advantage that the glue coating on the surfaces is applied after the web is stabilized by the thermally conditioned bond.

Opfindelsen er i en foretrukket udførelse vist skematisk på medfølgende tegning.In a preferred embodiment, the invention is shown schematically in the accompanying drawing.

På tegningen er med 2 betegnet en formewire, som 10 har en fremløbsstrækning 4 nede under et par fordelerhoveder 6 for tilførsel af en blanding af løse cellulosefibre og varmeklæbende formstoffibre til fremløbet 4, hvorpå der derved dannes en florbane 8. Denne komprime-res mellem valser 10 og overføres derefter til en trans-15 portwire 12 via en overhead transfer station 14. Wiren 12 bringer floret gennem en varmezone 16, hvori de varmeklæbende fibre aktiveres til binding af cellulosefibrene. Derefter føres den nu stabiliserede florbane på selvbærende måde gennem et valsepar 18. Ved den kendte 20 teknik føres flor- eller produktbanen herefter til op-spoling i ruller for færdigvarer.In the drawing, a shape wire is indicated by 2, which 10 has a flow section 4 down below a pair of distributor heads 6 for supplying a mixture of loose cellulose fibers and heat-adhesive plastic fibers to the flow 4, thereby forming a floral web 8. This is compressed between rollers. 10 and then transferred to a transfer port 12 via an overhead transfer station 14. The wire 12 passes the web through a heat zone 16 in which the heat-stick fibers are activated to bond the cellulose fibers. Thereafter, the now stabilized floor web is passed through a roller pair 18. Self-supporting is carried out by a known pair of techniques. In the prior art, the floor or product web is then led to rewinding in rolls for finished goods.

Ved opfindelsen er der imidlertid efterkoblet en station 20, hvori banen 22 dobbeltsidigt pålægges et binderskum, fortrinsvis ved at banen nedstyres under en 25 omstyringsvalse 24, der samvirker på den viste måde med et V-formet bærebånd, idet der derved fra dyser 26 kan tilføres skummateriale 28 til bégge sider af banen.In accordance with the invention, however, a station 20 is provided in which the web 22 is double-sidedly applied to a binder foam, preferably by downgrading the web under a guide roller 24, which cooperates in the manner shown with a V-shaped carrier belt, thereby being able to supply from nozzles 26 foam material 28 for both sides of the web.

Derefter føres banen via et bånd 30 igennem en varmetun-nel 32, hvori den vandige andel af skumstoffet bringes 30 til at fordampe, således at banen 22 derefter kan føres til oprulning på den sædvanlige afgangsrulle 34.Then, the web is passed through a belt 30 through a heat tunnel 32 in which the aqueous portion of the foam fabric 30 is evaporated, so that the web 22 can then be reeled onto the usual discharge roller 34.

Claims

A method of making dry-laid paper material by successively laying a web of cellulose fibers on a molding wire and treating the web for bonding the fibers therein, known as the bonding of the fibers being induced by a combination of an activation of heat-adhesive bonding fibers. applied by prior blending into the cellulose fibers and applying glue to the surfaces of the web, this application being carried out with a dry matter content of substantially less than 10%, preferably 0.5-5%, for bonding the shortest cellulose fibers at over the fades.

Process according to claim 1, characterized in that the glue substance is applied in an amount of 15, 5-5 g dry matter per minute. square meter surface of the floral web.

Method according to claim 1, characterized in that the adhesive is applied to the surfaces of the web after it has been stabilized by thermally activating the heat-sticky binder fibers. 20 i>