| High strength dimensionally stable core -> Monitor Keywords |
|
|
 
High strength dimensionally stable coreRelated Patent Categories: Paper Making And Fiber Liberation, Processes And Products, Non-fiber AdditiveHigh strength dimensionally stable core description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060021725, High strength dimensionally stable core. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] This invention relates to paperboard, paperboard cores and tubes, and to a method for making cores and tubes. BACKGROUND OF THE INVENTION [0002] In the manufacture of paper, paper is wound onto cores. Cores are conventionally manufactured from laminated, spirally wound paperboard. It is important that cores have sufficient crush strength. Dimensional stability of cores is also important in roll handing operations. [0003] Moisture content in paper varies considerably from grade to grade depending on the manufacturing process. Similarly, paperboard cores are made at different moisture levels, depending on the absorption characteristics of the paperboard from which it is made and the adhesive used to glue the board layers to form a laminated core. As a result, in the winding of paper onto cores, there is typically a moisture content difference between the paper and the core. A difference in moisture content between the paper and core causes moisture to migrate. Moisture migration from the core to the paper and vice versa can cause corrugations and wrinkling in the paper, and in some cases core bursts, resulting in paper losses. [0004] Papermills today make wide paper rolls by winding different webs of paper onto a single core. Often, the different webs have different moisture contents, aggravating moisture migration problems. Further, these wide rolls require high strength cores to support the substantial weight of the paper. SUMMARY OF THE INVENTION [0005] It is an object of the invention to provide a high strength, dimensional stable paperboard core, with improved resistance to moisture migration. It is a further object of the invention to provide a high strength, water resistant paperboard that has utility in the fabrication of such cores. [0006] The core of the invention is manufactured from spirally wound paperboard having improved water resistance. The paperboard is made from a standard paperboard furnish. A preferred furnish comprises a mixture of 25-70% doubleliner kraft ("DLK"), and 25-70% recycled corrugated containers ("OCC"), and 30-50% recycled cores and/or other cores waste ("corebale"). The furnish should have a freeness of 150-275 CSF. The furnish is modified by adding 5-60 lbs/ton alum, 3-40 lbs/ton of liquid size, and 16-50 lbs/ton modified cationic starch. Other additives may optionally include 0.2-1. lbs/ton microparticle silica, and/or 2-8 lbs/ton of a dry strength agent, but are not required. [0007] A more preferred formulation has a paperboard furnish, 4-40 lbs of alum per ton of furnish (more ideally 4-12 lbs/ton of alum); 3-12 lbs of liquid size per ton of furnish, and 30-40 lbs of cationic starch per ton of furnish. [0008] It has been discovered that the combination of alum and a liquid size substantially improves water resistance. The alum improves drainage and helps reduce the swelling of wood fibers. Wood fibers swell when absorbing water. Significant drying energy or time is required to remove moisture absorbed by the fiber. Desirably the resulting paperboard has water absorption less than 400 cgs. [0009] A suitable alum product is aluminum sulfate solution available from General Alum & Chemical Corporation, Holland, Ohio. [0010] A preferred liquid size is Ultra-pHase.RTM. cationic dispersed size manufactured by Hercules Incorporated, Wilmington, Del. [0011] The modified cationic starch improves strength, especially in combination with alum. Cationic starch also contributes to drainage, thereby allowing for a reduction in the quantity of alum used. A preferred starch product is Penford Topcat 776 cationic additive, manufactured by Penford Products Co., Cedar Rapids, Iowa. Other suitable starch products are Avebee Amylofax 3300C and Amylofax-HS. [0012] The microparticle silica is added to improve the drainage in the paperboard making process. A preferred microparticle silica is Nalco 8692 Papermaking Aid, an aqueous dispersion of an inorganic hydrous oxide microparticle, manufactured by Nalco Chemical Company, Naperville, Ill. Other microparticle silica products may be used as well. [0013] The dry strength agent improves strength and contributes somewhat to improvement in water resistance. Suitable dry strength agent is Callaway 911 dry strength agent, manufactured by Vulcan Performance Chemicals, Birmingham, Ala. However, most dry strength agents are expensive additives and for this reason are less preferred. [0014] The forgoing optional additives are selected and added as required to produce the required properties of the core. For example, if a high strength is not required, one could use little or no starch or dry strength agents. Other additives could be used, for example a wet strength agent. [0015] The modified furnish is manufactured into paperboard by known manufacturing techniques, such as fourdrinier or multiple cylinder papermachine, to produce a finished paperboard having a basis weight of 50-142 lbs per 1000 sq/ft., a caliper of about 0.013 to 0.041 inches, a density of 0.7 to 1.0 g/cm.sup.3 and a moisture content of between about 3-6 percent. The moisture content of the cores preferably should be as close as possible to the moisture content of the paper to be wound onto the cores. [0016] The paperboard is then wound with conventional core machinery to form paperboard cores having between 3-32 plies. For example, one embodiment of the invention comprises high strength cores for paper rolls, which have 20-32 plies. Another application of the invention is for cores for adhesive tape and other small tube applications, which have 3-7 plies. In smaller cores made in accordance with this disclosure have a lower core crush variability due to humidity and improved dimensional stability. The preferred adhesive used in winding the cores is polymer base, such as latex or polyvinyl alcohol; however, other adhesives like dextrins may be used. [0017] Testing on the cores made in accordance with the foregoing exhibited increased crush strength, and increased water holdout. The cores exhibited reduced moisture carry over, and low core length shrinkage. Other benefits include reduced core warpage and less variability in core inner and outer diameter. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS [0018] Examples of the improved high strength, dimensional stable cores of the invention are provided as follows: GP1 STANDARD [0019] The furnish comprised: 950 lbs DLK, 1,000 lbs OCC and 1,400 lbs corebale. Paperboard was manufactured from the furnish on a conventional board machine. The resulting paperboard had a caliper of about 0.02 inches and a basis weight of about 80 lbs/1,000 square feet. The core was wound in conventional process, having a lead-in ply and 30 structural plies formed with the above furnish. The cores had an internal diameter of 3.025 inches and a wall thickness of 0.66 inches. Continue reading about High strength dimensionally stable core... Full patent description for High strength dimensionally stable core Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this High strength dimensionally stable core 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 High strength dimensionally stable core or other areas of interest. ### Previous Patent Application: Process for bio-bleaching of kraft pulp using bacterial consortia Next Patent Application: Flexible drainage systems and methods Industry Class: Paper making and fiber liberation ### FreshPatents.com Support Thank you for viewing the High strength dimensionally stable core patent info. IP-related news and info Results in 0.14414 seconds Other interesting Feshpatents.com categories: Canon USA , Celera Genomics , Cephalon, Inc. , Cingular Wireless , Clorox , Colgate-Palmolive , Corning , Cymer , 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
