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Method for producing fiber productRelated Patent Categories: Paper Making And Fiber Liberation, Processes And Products, Multi-layer Waterlaid Webs Or Sheets, Layers Of Different PropertiesMethod for producing fiber product description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060032596, Method for producing fiber product. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The present invention concerns a method according to the preamble of claim 1 for producing a multilayered fiber product. [0002] According to a method of this kind, on top of a bottom layer consisting of at least one fiber layer there is fitted a second fiber layer, which contains a filler and which forms the surface layer of the fiber product. [0003] In coating, the purpose of the base paper is to create problem-free operation conditions for the coating unit and finishing stages and to create a base for the coating during printing. [0004] The grammage of normal LWC paper varies between 40 and 80 g/m.sup.2, of which 6-15 g/m.sup.2 per side comprises the coating layer. When moving towards lower grammage, the properties of the base paper become more critical. For thin paper grades, the coating layer cannot, by itself, compensate for the properties of the base paper, and because of this, in particular roughness and pore size (porosity) have great impact on the surface smoothness of the coated paper and, thus, also on the printing result. [0005] Roughness increases when the roughness or the pore size increases in paper coated with low amounts of coating colours. By adding fines or fillers to the paper it becomes possible to decrease paper roughness. [0006] It has been observed that, when using porous base paper, the coating penetrates strongly into the base paper structure in doctor blade coating or in film coating. A denser base paper provides improved covering. Poor covering is immediately visible as impaired quality or unevenness in the printing result or it can lead to an increase in the quantity of coating material required. [0007] The quantity of fillers in LWC base paper is normally 5-15%. Typically, approximately half of the filler is derived from coated rejected material and half comprises fresh feed. Fillers are used to improve the optical and printing properties of the paper, although paper strength properties suffer simultaneously. This may result in runnability problems at the paper machine. Furthermore, filler pigments are less expensive than fiber. It is therefore profitable to keep the quantity of fillers as high as possible. [0008] A process for making multilayer webs by multilayer web technology is known from FI Patent No. 92729. In the process, there is a paper machine comprising a multilayer headbox, and different pulps are formed in at least two separate distribution funnels from the same fresh pulp and from the same pulp material deposit. The fresh pulp is fed from the material deposit and divided into several suspension flows, which are fed to the multilayer headbox. "The chemicals and/or additives relevant to quality and making economy" of different paper qualities are fed into the suspension flows. [0009] Multilayer web technology is also described in FI Patent No. 105 118 and in EP Published Patent Applications Nos. 824 157 and 1 152 086. [0010] It has been observed that layering of the pulp improves paper surface smoothness. For example, if mechanical pulp containing high quantities of fines is layered on the surface layer, the smoothness of the layer structure will be improved. If, at the same time, bulky chemical or mechanical pulps are placed in the middle layer, the bulk of the paper can also be improved. [0011] It has further been observed that layering of the filler onto the surface layers improves sheet smoothness compared with the surface of the non-layered sheet. [0012] In known technology, multilayer web technology is recommended for use in objects, where the quality of paper or board has generally been improved by pre-coating. These are writing and printing papers, fine papers (coated and non-coated), LWC base papers and SC papers, for example. [0013] Although several problems related to conventional technology have been removed, the surface layer of a multilayer product still requires good formation, which is manifested as good printability in addition to smoothness. Thus, poor formation can most clearly be seen in the grey shades of offset printing and as a mottled printing surface. In order to improve the retention of the ordinary fillers, they are used together with retention agents. These agents cause flocking, which further decreases formation. [0014] It is an aim of the present invention to eliminate the drawbacks related to known technology and to provide an entirely new solution for making multilayer papers and boards. The purpose of this invention is, in particular, to provide a new process for making these multilayer products, where the surface is extremely smooth, air permeability resistance is high, the formation is high combined with good optical qualities (high opacity, ease of coating). [0015] The invention is based on the idea of forming the different layers of a multilayer product from fresh pulps containing fibrous raw material using the multilayer web technology. In this technology, the furnish is prepared in the multilayer headbox of a paper machine for layering such that fillers and additives are added to the pulp used for the surface layer/layers of the multilayer product, and after this, the pulps are fed separately and combined immediately before the lip of the headbox, where the pulp slush jet is then fed onto the wire. According to the invention, the filler used in the surface layer is at least partially formed by a composite filler, which contains cellulosic or lignocellulosic fibrils, on which light-scattering material particles have been deposited in such way that their maximum content is 85% of the weight of the filler. These types of fillers are disclosed in our FI Patent Specification No. 100729. [0016] According to the present invention it has surprisingly been found that when the surface layer of a multilayer product is filled with the above mentioned filler, the opacity of the surface increases so much that the grammage of the surface layer can be significantly decreased. [0017] Furthermore, in this invention it has been observed that, in addition to the above mentioned low-cost filler, other corresponding fillers can also be used, which at least partially consist of cellulosic or lignocellulosic fibrils, on which light-scattering material particles are deposited. These particles are typically inorganic salts, such as calcium carbonate, calcium sulphate, barium sulphate or calcium oxalate that are precipitated in aqueous phase. [0018] The use of composite fillers in multilayer products is disclosed in our previous FI Patent Application No. 20010848. There is no mention of the multilayer web technology in that application. Instead, the application suggests combining the separate layers by vat lining. In the present invention, the layers are formed simultaneously by multilayer web technology and they are dried on the wire, to which they are fed simultaneously from the lip of the headbox. [0019] US Patent Application No. 2001/0045265 discloses a process and a device for producing a multilayer web, where calcium carbonate is precipitated on at least one fiber layer in connection with the web making. In the reference, the calcium carbonate is not precipitated on fibrils, but on the fibrous material. [0020] More specifically, the method according to the invention is mainly characterised by what is stated in the characterizing part of claim 1. [0021] Considerable benefits are achieved with this invention. Thus, with the help of the invention, paper having even quality and a high formation level can be produced at good retention. In addition, the recirculation waters become significantly cleaner and the need for retention agents decreases. Improved formation results in a smoother paper having improved gloss. The improved smoothness is a significant factor as illustrated in the examples below: it is surprisingly good and considerably much higher than what was expected. If the paper is coated, the coverage of the coating is better than with conventional, mineral-based fillers. This makes it possible to use smaller quantities of coating. Moreover, problems related to unevenness of gloss and of the printing results are decreased. [0022] The present products can be used in writing and printing papers (coated and non-coated fine papers, LWC and SC papers) and in different kinds of boards. According to the invention, the multilayer product has high density, which is why the invention is particularly advantageous for thin, coated paper qualities (LWC, SC), in which coating color intrusion inside the base paper, and through it, is a conventional problem. [0023] Due to their density and good air permeability resistance, product types based on the invention are also applicable for usages where barrier qualities are of importance. Examples of these types are envelope papers, barrier papers and barrier boards in food and cleanser packages. [0024] It has been observed that the filler improves surface layer formation and structural stiffness. The filler disclosed in FI Patent Specification No. 100729, for which the product name "SuperFill" is also used in the following, has good retention, whereby the quantity of retention agent can be decreased and yet the system remains cleaner. Improved retention also promotes a decrease in optimisation/dosing of other paper making additives. Cleanliness favours runnability of the machine and, in general, machine operating efficiency improves, because the number of stoppages decreases. Continue reading about Method for producing fiber product... Full patent description for Method for producing fiber product Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method for producing fiber product patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method for producing fiber product or other areas of interest. ### Previous Patent Application: Method of making a paper web containing refined long fiber using a charge controlled headbox and a single ply towel made by the process Next Patent Application: Control method and an adjustment method and a control arrangement and an adjustment arrangement for a fibre web machine Industry Class: Paper making and fiber liberation ### FreshPatents.com Support Thank you for viewing the Method for producing fiber product patent info. IP-related news and info Results in 0.63069 seconds Other interesting Feshpatents.com categories: Daimler Chrysler , DirecTV , Exxonmobil Chemical Company , Goodyear , Intel , Kyocera Wireless , 174 |
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