(12) Patent Application Publication (10) Pub. No.: US 2015/0013926 A1 JAAKKOLA Et Al
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US 2015 0013926A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2015/0013926 A1 JAAKKOLA et al. (43) Pub. Date: Jan. 15, 2015 (54) METHODS AND APPARATUS FOR FORMING (52) U.S. Cl. FLUFF PULP SHEETS CPC ..................................... D2IH 27/30 (2013.01) USPC ........................................... 162/123; 162/141 (71) Applicant: INTERNATIONAL PAPER COMPANY, Memphis, TN (US) (57) ABSTRACT An improved processes for making fluff pulp sheets mechani (72) Inventors: JYRKI T. JAAKKOLA, Lawrenceville, cally eliminates many of the unwanted fiber-to-fiber bonding GA (US); JAMES E. SEALEY, (fiber bundles) which may be contained in the sheet to pro Anderson, SC (US) duce consistent and uniform quality fluff pulp. Pulp slurry is deposited on a moving bottom forming wire to form a stock (21) Appl. No.: 14/504,487 web. Pulp slurry is brought into contact with a moving top 1-1. forming wire. The stock web is subjected to up and down (22) Filed: Oct. 2, 2014 dewatering creating separately formed layers to reduce fiber O O to-fiber bonding. The stock web can be subjected to strong Related U.S. Application Data pulsating shear forces as it is being advanced along the bot (63) Continuation of application No. 13/398,144, filed on tom forming wire to break a majority of fiber bundles con Feb. 16, 2012, now Pat. No. 8,871,059. tained in the web. The pulp slurry can be deposited on the bottom forming wire utilizing aheadbox with dilution control Publication Classification to selectively adjust the concentration of the pulp slurry. A shoe press can be used to dewater the web after it is subjected (51) Int. Cl. to the pulsating shear forces. The web can be dried utilizing D2 IIH 27/30 (2006.01) conventional drying equipment, such as cylindrical driers. Patent Application Publication Jan. 15, 2015 Sheet 1 of 4 US 201S/0013926 A1 YN lS S \ SS s S s lf S Su1N S S Patent Application Publication Jan. 15, 2015 Sheet 2 of 4 US 201S/0013926 A1 20at Néscsa IIIT IIIATILIA sessO Y - 18 38 FIG 3 36 36 e 2ZZZZZS 22 aaaaaaaaaa 2Zazz Statetetetetatata2 X 42 38 18 Patent Application Publication Jan. 15, 2015 Sheet 3 of 4 US 201S/0013926 A1 Traditional singleply Stock preparation FIG, 4 Headbox With Or Without dilution Control Top former Roll press(es) COmbined With multiple Shoe press(es) Single Shoe press Shoe presses FIG 5 Multilayering Headbox Multiple Headboxes With Or Without With Or Without dilution Control dilution Control Multiple Top formers Top former H Fourdriniers Roll press(es) Single Shoe press COInline With or multiple Shoe press Shoe presses Patent Application Publication Jan. 15, 2015 Sheet 4 of 4 US 201S/0013926 A1 Additive multilayering FIG 6 start prep Multilayering Headbox With Or Without Dilution Control Roll press(es) COmbined With Single shoe press or Shoe press(es) multiple Shoe presses pulp Slurry pulp slurry additives pulp Slurry additives US 2015/0013926 A1 Jan. 15, 2015 METHODS AND APPARATUS FOR FORMING onders prior to sheet formation. Therefore, important param FLUFF PULP SHEETS eters that are considered for dry defibration are shredding energy, i.e., the amount of energy needed to shred the sheet BACKGROUND OF THE INVENTION and knot content, i.e., the amount of clumps of fibers bonded 0001. This invention relates generally to wet forming pro to each. In heavy manufacturing operations, reduction in cesses for making fluff pulp from Soften wood pulps and, energy consumption will ultimately lead to less costly prod more particularly, to improved processes for making fluff ucts. Moreover, many manufacturers require high quality pulp sheets which eliminate many of the unwanted fiber-to fluff pulp to be used in their products due to customer fiber bonding (fiber bundles) that may be contained in the demands. Accordingly, manufacturers of fluff pulp sheets are sheet to produce consistent and uniform quality fluff pulp. concerned in creating sheets having low shredding energy These improved processes also permit the manufacturer to while still providing high quality fluff. Lower quality fluff control the consistency of the stock being formed by localized pulp sheets cannot be used in certain applications and as Such dilution to achieve a better cross-machine directional basis are often discounted for use in manufacturing lower quality weight allowing the manufacturer to produce high quality products. fluff pulp while using low headbox consistency. Fluff pulp 0004 Wood pulp softness can be expressed in terms of produced by the processes of the present invention is soft, properties such as Mullen strength (the strength of pulp or a flexible, and has a lower content of knots or hard spots. The pulp product, measured in kilopascals (kPa)), and Kamas processes of the present invention are capable of producing energy (the energy required to converta given amount of pulp fluff pulp sheets having low variability in weight, moisture, or pulp product to a fluff material, measured in watt hours per Mullen strength and other physical sheet attributes. Accord kilogram (Wh/kg)). Mullen strength can be thought of as the ingly, a fluff pulp sheet made in accordance with the present energy required to pop a hole in the sheet. Some in the invention should have low shred energy while possessing industry refer to this energy as “burst energy.” Mullen high shred quality which results in significantly reduced strength is a good indicator (but not full proof) of the energy fiberization energy when the sheets are ultimately processed. needed to shred the sheet (shred energy). Typically, the lower The invention is especially useful for the production of fluff the Mullen strength, the easier it is to shred the fluff pulp pulp intended for use as the absorbent layer in disposable sheet. Lower values of Mullen strength and Kamas energy diapers, sanitary napkins, absorbent hygienic products and also correlate to softer, increasingly debonded, pulp. While it airlaid products. is desirable to the manufacturer to decrease Mullen strength, 0002 Absorbent products employing fiberized wood pulp it should not be done at the expense of shred quality. have been available for many years. This basic wood pulp 0005. In the art of making fine paper, stock is usually used in such products is usually termed “fluff pulp. In the ejected from a device known in the industry as a headbox so United States, fluff pulp is most typically made from a fully as to land gently on the moving fabric loop, known as a bleached Southern pine kraft process pulp produced in rela forming wire, which moves at a speed typically between plus tively heavy caliper, high basis weight sheets. The product is or minus 3% of the wire speed, called rush and drag respec rewound into continuous rolls for shipment to the customer. tively. In the manufacture of fluff pulp, the equipment is Since the roll product is intended to be later reprocessed into usually run at about +10% rush. Excessive j/w ratio helps the individual fibers, low sheet strength is desirable and typically Mullen strength. Water drains from the stock through the little or no refining is used prior to roll manufacturing. The forming wire so that a web is formed on the forming wire. requirements for Surface uniformity and formation are simi Excessive rush or drag can cause more orientation offibers of larly moderate. the web in the machine direction and can give differing and 0003. At the customer's plant, the rolls are continuously Sometimes unwanted physical properties in machine and fed into a device. Such as a hammermill, to be reduced as cross directions. Manufacturers, therefore, are concerned much as reasonably possible to individual fibers. Defibration about fiber orientation and accordingly have to control the is the process of freeing the fibers from each other before the orientation of fibers being deposited on the forming wire in fluff pulp enters the product forming machinery. The fiber order to achieve the desired physical properties. ized product is generally termed a cellulose “fluff.” For 0006. As was mentioned above, wood fibers have a ten example, the fluff pulp can then be continuously air laid into dency to attract to one another, forming clumps, the effect pads for inclusion in the intended product. The most demand being called flocculation. Flocculation is lessened by lower ing application offluff pulps is in producing air-laid products, ing consistency and or by agitating the slurry entering or in used, for example, in serving utensils and various towel appli the headbox. However, deflocculation becomes very difficult cations in homes, industry and hospitals. AS is mentioned at much above 0.5% consistency. Minimizing the degree of above, fluff pulp sheets for air-laid products are usually defi flocculation is important to the physical properties of the fine berized in a hammermill. Fluff pulp sheets, however, may paper or fluff pulp. contain significant numbers of fiber bundles which are 0007 Usually, the stock is supplied at extremely high bonded together during the sheeting process. These unwanted pressure to the headbox by means of pumping equipment and fiberbundles, often referred to as knots, nits, bones and flock the stock is ejected from the headbox through a device known in the industry, present a problem during defibration. The as slice lip. Accordingly, it is essential that the rate of flow of hammermills used for fluff production are very large energy stock through a distributor tube disposed at one side of the consumers and fiber bundles present in the fluff pulp sheets headbox be the same as the rate of flow of stock moving will increase the amount of energy expended during defibra through a distributor tube disposed at the opposite side of the tion.