Soft Nip Calender Research Articles

Impact of different calendering strategies on barrier coating pickup

Paper was pre-calendered in a pilot scale configuration with a traditional soft nip calender and a metal belt calender. All calendering strategies reduced surface roughness and permeability of the samples, but different strategies affected the surface roughness and permeability differently. The metal belt calender seemed to have a larger effect on the large-scale variations compared to the soft nip calender. Six test points from the pilot calendered papers were chosen for laboratory coating studies. Uncalendered paper was included as reference samples. The calendered samples and the reference were pre-coated with a regular pigmented coating consisting of a ground calcium carbonate (GCC) pigment and a styrene acrylate (SA) latex. Both uncoated and pre-coated substrates were barrier coated with a polyvinyl alcohol (PVOH) in one and two layers. The coating pickup was determined gravimetrically, and the barrier properties were evaluated with TAPPI Standard Test Method T 454 grease resistance test. All samples needed two PVOH coating layers to form a grease barrier. The uncalendered sheets showed the best results with one coating layer, but this was at the expense of a higher coating pickup compared to the calendered sheets. The barrier coating pickup could be reduced by a combination of high temperature metal belt calendering and pre-coating. The high temperature and long residence time in the nip enabled plasticization of the fibers. This led to an irreversible deformation, even after water application. This meant that the smoothness obtained during calendering would be less affected by water-induced roughening during the coating operation.

Development of In-Line Printing Press Calendering Station

Metallic conductive inks used for printed electronics have a tendency to create low conductivity layers unless they are fully dried. Yet, even after the drying, conductivity can be further improved by a post-heat-cure process. A hot soft nip calender was modified to be able to place it in line with a flexographic printing press and to study the effect of calendering on electrical performance of printed conductive layers. Two print trials were performed on the Comco Commander Flexographic Press at the Western Michigan University (WMU) Printing Pilot Plant with the calender placed in line with the moving web of the press. Three substrates were employed, a commercial label paper, a folding carton boxboard and a polyethylene-terephthalate (PET) polymer film. Two inks, one containing silver flakes and the other silver nanoparticles, were employed to print conductive layers during the print trials. Traces (lines) were printed using a three-banded anilox roll, with different cell volumes, to study the effects of ink transfer. The results were analyzed to evaluate the effects of the design variables, calender nip temperature and pressure, anilox cell volume, ink and substrate on electrical performance of printed silver inks.The results showed that, for all inks and substrates, the electrical resistance is reduced at higher nip temperature and pressure, relative to that without calendering. Furthermore, the same resistance can be obtained with a lower anilox cell volume and calendering than with higher cell volume but without calendering. This translates to a higher ink mileage (lower ink usage) for the same electrical performance if the calendering is used. The economic benefits of this are large, because of the high cost of the silver inks.

Modeling of the compression of coated papers in a soft rolling nip

An analytical model is developed for the compression of coated substrates in a soft rolling nip formed between a hard roll and a soft covered roll. The coating layer, substrate, and soft cover are modeled as a stack of three layers that are compressed jointly while passing through the nip. Material models have been adopted separately for each of the three layers and were combined together according to the thickness of individual layers. In this study, the substrate is considered to be a viscoelastic–plastic material and is represented by a modified solid element while the coating layer is assumed to be elastic and the soft cover material is approximated by a standard Maxwell model. A strain function is derived for the compression of substrate in the nip that appears to be a parabolic function of time. Substrate compression in the nip and its subsequent relaxation are calculated by solving a set of differential equations that describe the coating, substrate, and soft cover deformations. This model is used to study the soft-nip calendering of coated papers. Examples of numerical modeling that demonstrate the paper deformation and stress profiles in the nip are presented. In addition, the effects of paper and cover properties as well as calendering parameters on the dynamics of paper compression are discussed. Finally, a comparison of the modeling results is made with the experimental data.

The compressive response of a stratified fibrous structure

A model for the compressive response of an oriented fiber structure such as paper is derived in this work. The model provides a semi-quantitative description of the stress/strain behavior of a fiber structure. The model accounts for the deformation of fibers during compression, their finite fiber length, their elastic modulus, and their moment of inertia. Using a previously describe micro-indentation technique, the predicted impact of variables used in the model on the compressive response of paper is verified. Results consistent with the model are found including a strong dependence of the tangent modulus on apparent density of the sheet, and a relative insensitivity of the tangent modulus to fiber length. The three stage behavior of the paper compression described by Rodal [Soft-nip calendering of paper and paperboard. Tappi Journal 72 (5), 177–186] was also accounted for in the model.

Impact of high temperature and soft nip calendering on the pore structure of the coating layer

Article Impact of high temperature and soft nip calendering on the pore structure of the coating layer was published on May 1, 2002 in the journal Nordic Pulp & Paper Research Journal (volume 17, issue 2).

Effect of high-temperature and soft-nip calendering on the density of paper

Effect of high-temperature and soft-nip calendering on the density of paper

７号抄紙機の操業経験

Mitsubishi Hachinohe Mill with seven paper machines including two on-machine coater is capable for producing 70, 000 ton of papers per month. Among seven paper machines. paper machine No. 7 (PM 7), which has been operated since 1997, is the latest paper machine in Mitsubishi Paper Mills Limited and produces approximately 400 ton of fine paper and coat base per day.PM 7 has been designed to get high productivity and good quality of the products by introducing the latest paper making technology and devices at that time. The introduction of PM 7 is a technological step for us to a wider paper machine than PM 7 in future.In this report we describe an outline of equipment on PM 7 and its operational experiences. Major items reported here are as follows : (1) Module jet Headbox which makes optimum base weight profile by controlling the stock consistency on the cross machine direction, : (2) Transfer Felt System which actualizes the smooth running of the wet web with high speed in the press section, (3) Shoe-Press ENP-C which introduces high consistency at the outlet of the press section, (4) Symsizer available for heavier coated weight than other size press coater, (5) Web Threading Device without rope in pre dryer, (6) Soft Nip Calender, and (7) Opti-Reel with center drive type.We have been remarkably successful in startup of PM 7 heretofore. However we still have a few operative problems which we have to settle. Gaining our customer's perfect satisfaction, we keep on making an effort to improve quality of products.

Theory and Development of Calendering

In the area of sheet formation, calenders play apparently very important part to decide final paper quality.Lately multi nip machine calenders are required long experienced skill to gain stable CD profilecorrections by excluding roll deflection of nip forces, annular deformation caused by thermal profilingand correlation of variations affected by differences.Recently, several profiling systems have been developed to minimize such variation during finalcalendering. Particularly, soft nip calendering has been remarkably introduced with its correction capacityfor better smoothness, printability and tensile strength. Superior correction potential of soft nipcalendering is reported here in comparison of machine calenders with the examination of several factorsaffecting CD profilingFurther. Crown Controlled Roll for eliminating narrow and broad wave profile deviations is introducedwith precise explanation of design and functional concept, correction potential and its control systems.

Operating Experience of N 2 PM Dry Part

N 2 PM for newsprint was started up in February, 1998. at Nippon Paper Yatsushiro Mill. The design speed of this paper machine is max. 1, 700m/m. The wire wid this 9, 050mm.This paper machine is one of the wide and high speed machines in the world. This machine has alot of the newest equipments based on the newest paper making technologies in the world or Japan. andthe automatic equipments. Our mill can efficiently produce and continuously supply the best qualitynewsprint to the press rooms of Kyushu area by this N2PM.This paper mentions about the outlines from the dryer part to reel part and the operating experienceat these parts from start-up. As for the outlines, the configuration of this N 2 PM dryer is the topdeck and single canvas dryer at the both of pre-dryer part and after-dryer part. And the calender isthe soft-nip calender, because we can reduce the two-sidedness of paper, and produce good printabilitynewsprint by this calender. The users already recognize the newsprint quality of N 2 PM is the best.And as for the operating experience, this paper mentions about the sheet break and the paper threading.We are going to try to operate this paper machine at 1, 700m/min the future.

Lubricant for Paper Coating

Coating lubricant is used as an anti-dusting agent at calendering and printing process, a releasing agent at cast coating process, a slipping and an anti-blocking agent of paper and smoothness and gloss improver of paper.For paper coating lubricant, calcium stearate dispersion which San Nopco introduced from USA about 30 years ago is still widely used.Recent coating technology enables them to use SBR with lower Tg for gravure grade coated paper but it requires new lubricant which prevents dusting at supercalendering process. Modern high speed cast coater needs a lubricant which has better releasing property and can extend operation time without break for cleaning casting drum. Soft nip calender requires a lubricant which shows good releasing property at higher temperature. As above mentioned, recent progress in paper coating requires various performance to lubricant. San Nopco i developing new lubricants to meet these requirements and supplying them to paper manufacturers.In this report, I introduce the performance and function of our high performance lubricants.

Influence of the calendering conditions on the structure and the properties of woodfree paper - A comparison between soft nip calendering and hard nip calendering.

Article Influence of the calendering conditions on the structure and the properties of woodfree paper - A comparison between soft nip calendering and hard nip calendering. was published on January 1, 1998 in the journal Nordic Pulp & Paper Research Journal (volume 13, issue 1).

次世代マルチニップカレンダー オプティロード

For the calendering system, soft nip calender and supercalender have been used to attain required surface qualities of various grades of paper. Polymer rolls have been developed for soft nip calenders. In the supercalender technology some developments have been seen such as application of zone-controlled rolls, overhanging load compensation, zoned steam shower, replacement of cotton filled rolls by polymer rolls and so forth. In both calendering systems there are respective benefits and shortcomings even today.A lot of challenging works have been done in order to design and produce more effective calender. As the results, now we, Valmet can supply new generation multinip calender-OptiLoad for customers after experiencing the various steps of improvements of multinip calenders.

塗工技術 高速ブレードコーターの制御 コーターにおける塗工量制御とソフトカレンダにおけるキャリパ制御

大型塗工マシンが増加している昨今, 塗工プロセスでの製品品質向上と原価削減への取り組みが進んでおり, 人手による調節操作では, 品質的にも生産効率でも限界となってきている。コータ・ブレードの自動制御, ソフトニップ・カレンダでのキャリパ制御, スーパーカレンダでのグロスの向上等, 新たな制御の導入が進んでいる。塗工量の幅方向制御では, 塗工量の変動を早く正しく測定することが重要であり, そのため, 塗工量センサが開発されている。塗工量計を使用したブレード制御の実績も多くなっている。ソフトニップカレンダのキャリパ幅方向制御は, 冷熱風方式のアクチュエーターによるキャリパ制御導入が増加しており, その制御性や保守性で高い評価を得ている。スーパーカレンダでは, グロスの向上を目的に蒸気噴霧アクチュエータの取付けが増えており, 紙品質に問題を与えない安全性の高いものが実用化している。これら塗工紙関係の測定/制御について, 塗工量測定と制御, ソフトニップ・カレンダでのキャリパ制御, グロス制御アクチュエータの概要, および幅方向制御信号の処理技術について紹介する。

高温ソフトニップカレンダー掛け その導入

One of the key technological events of the 1980's in papermaking was the development and implementation of the soft nip calendering, on or off-line, The technology found many applications and is gaining acceptance around the world. When some of the present technical problems are resolved, it may become a standard feature of all paper machines.As the CD profile control technology continues to improve, the primary role of the calender has been shifting from the traditional reel building tool to that of surface finishing. During the second half of the 1980's, we examined the technology for various paper and paperboard operations. In this paper, I would like to share with you some of our findings from pilot trials and laboratory evaluations.High temperature soft nip calender (HTSNC) has a nip that is hot, long and of low specific pressure. It works primarily on the small scale roughness of the paper surface. This may or may not be of practical value depending on the paper grades and their end-use requirements. Benefits from new technology can never be scrutinized too much.