PAPER SIZING

Abstract: A method for improving high speed precision paper converting and reprographic operations by surface sizing paper used in high speed precision converting or reprographic operations with a reactive sizing agent and an inorganic filler, the filler being applied in an amount effective to improve paper runnability. A sizing composition useful as a surface size in this invention is a 2-oxetanone reactive sizing agent and an inorganic filler, in a weight ratio of inorganic filler to reactive surface size of about 0.1:1 to about 10:1. Paper made by this method is also within the scope of this invention.

Description: TITLE PAPER SIZING BACKGROUND OF THE INVENTION This invention relates to a method of improving high speed precision conversion performance of paper by surface treating paper with a reactive sizing agent and a filler and to paper so made. Manufacture of paper produced under alkaline conditions has increased rapidly in recent years. Alkaline fine paper generally performs well in most down stream end use applications, but high speed converting and high speed reprographic operations often present severe paper handling requirements for paper so used, including alkaline fine paper. Precision converting applications for alkaline fine paper, such as forms bond and copy paper, can result in high speed runnability problems. Typical handling problems associated with high speed converting or high speed reprographic operations using alkaline fine paper containing an internal reactive size include reduced operating speeds, double feeds or jams in high speed copiers, paper welding, and registration errors on high speed folding equipment and printing equipment. Alkaline paper grades that are often used in high speed precision handling equipment include copy paper, forms bond, envelope paper and adding machine tape. These paper grades represent a significant segment of the market for alkaline fine paper so there is a need for alkaline fine paper suitable for use in high speed precision converting applications, including high speed reprographic operations. Sizing agents are typically added to alkaline fine paper, either as an internal sizing agent or as a surface-applied sizing agent to effect changes in the paper's physical characteristics, e.g., the sizing property of the paper, a measure of the resistance of a manufactured paper to the penetration or wetting by an aqueous liquid. The sizing property and sizing agent used can have a significant impact on the handling characteristics of the paper in subsequent end use applications such as high speed converting or reprographic operations. Sizing agents are therefore often added to alkaline fine paper as internal sizes to improve the runnability of the paper-making equipment and of the performance of the resultant paper in end use applications. - 2 - The two most commonly used internal sizing agents for paper made under alkaline conditions are alkyl ketene dimer (AKD) and alkenyl succinic anhydride (ASA). Both of these sizing agents are so-called reactive sizes since each has a reactive functional group that covalently bonds to cellulose pulp and hydrophobic tails that are oriented away from the pulp once the size-cellulose reaction has occurred. The nature and orientation of the hydrophobic tails on the reactive sizes provide the water-repellency property in the sized paper. AKD- and ASA-based reactive sizing agents are widely used in commercial practice for sizing alkaline fine paper but each has shortcomings that adversely affect the manufacturing processes used to make alkaline fine paper internally sized with either of these sizes. Moderate addition levels of ASA as an internal size can cause undesirable deposits on the papermaking equipment, web breaks and holes in the paper. Addition levels of ASA-based sizing agents of about 1.0 - 1.25 kg/metric tonne of paper generally lead to unacceptable papermaking machine runnability and paper quality problems. However, addition levels greater than 1.0 - 1.25 kg/metric tonne of paper are often required to meet end-use sizing requirements, especially for high levels of filler added to the paper furnish. AKD-based sizing agents are more satisfactory than ASA-based sizing agents in these respects, but AKD sizing agents generally exhibit a slower rate of size development than ASA sizing agents. Consequently, an extended period of curing may be required with alkaline paper internally sized with AKD before its sizing development is complete. However, AKD sizing development is generally completed by the time the paper has reached the reel in the papermaking process. Both ASA- and AKD-based sizing agents have been associated with handling problems in high speed paper handling applications for alkaline paper internally sized with these sizing agents. Non-reactive polymeric sizes such as styrene maleic anhydride (SMA) avoid many of the paper handling problems on high speed converting equipment and high speed reprographic equipment associated with AKD and ASA, primarily due to the high molecular weight of such polymeric sizes. Polymeric sizes are generally applied as a surface size typically at the size press in the papermaking process, in contrast to the internal addition of ASA- and AKD-based sizing agents. - 3 - Despite this apparent advantage of polymeric surface sizes, ASA- and AKD-based sizing agents are nevertheless preferred in commercial papermaking processes because of their cost and sizing efficiency. Polymeric surface sizes, on a weight basis, are 50% more expensive than AKD- and ASA-based sizing agents. In addition, AKD and ASA exhibit very high relative sizing efficiency, being 2-3 times more efficient than a typical polymeric surface size on an equal weight basis. These factors make both AKD- and ASA-based sizing agents far more cost- effective and efficient for obtaining a given level of sizing development in paper. Consequently, there is a need to improve the high speed converting and reprographic performance of alkaline fine paper that is sized with a reactive size, such as AKD, ASA, or the like. Reactive sizes such as AKD may be categorized as 2-oxetanone sizing agents, which include ketene dimers containing one β-lactone ring, e.g., alkyl ketene dimers, and ketene multimers, containing more than one such β-lactone ring, e.g., alkyl ketene multimers. Such 2- oxetanone reactive sizing agents and their preparation are described in EP-A1-0 629 741 of Zhang et al., in U.S. Patent 5,685,815 of Bottorff et al., and in U.S. Patent No. 5,846,663 of Brungardt et al., the disclosures of which are hereby incorporated by reference. The present invention provides for improved high speed runnability of alkaline fine paper that is surface treated with a reactive size. SUMMARY OF THE INVENTION One aspect of this invention is a method of improving high speed precision paper converting or reprographic operations by surface sizing paper used in high speed precision converting or reprographic operations with a reactive sizing agent and an inorganic filler, the inorganic filler being applied in an amount effective to improve paper runnability with the weight ratio of inorganic filler to surface sizing agent being about 0.1 : 1 to about 10:1. Another aspect of this invention is a method of improving high speed precision paper converting or reprographic operations by surface sizing paper used in high speed precision converting or reprographic operations with a reactive sizing agent that is a 2-oxetanone that is a liquid at 35 °C and an inorganic filler selected from the group consisting of kaolin, titanium dioxide, silicon dioxide, bentonite and calcium silicate, the inorganic filler being applied in an amount effective to improve paper runnability with the weight ratio of inorganic filler to surface sizing agent being about 0.1 : 1 to about 10: 1. - 4 - Still another aspect of this invention is a sizing composition useful as a surface size for alkaline fine paper comprising a 2-oxetanone reactive sizing agent that is a liquid at 35 °C and an inorganic filler, the weight ratio of inorganic filler to reactive sizing agent being about 0.1 : 1 to about 10:1. Paper made by the method of this invention is yet another aspect of the present invention. DETAILED DESCRIPTION OF THE INVENTION The method of the present invention provides for the improvement of high speed precision paper converting performance and reprographic operations with surface-sized paper used in such operations by the application of a reactive surface size to alkaline fine paper in combination with an inorganic filler, both being applied to the surface of the paper and the inorganic filler being present in an amount effective to improve paper runnability with the weight ratio of inorganic filler to surface sizing agent being about 0.1 : 1 to about 10: 1. "Precision" converting, as used herein, refers to precision high speed converting and reprographic operations carried out on equipment that handles high throughput paper volumes, requiring-precise control during such high rate paper handling. The linear speed at which paper is processed through precision converting equipment is high, e.g., about 500 to about 2000 ft/min (about 160 to about 660 m/min) being typical, with cut size paper generally being sheeted at the lower end of this range, i.e., about 500 to about 850 ft/min (about 160 to about 280 m/min). Precision high speed reprographic equipment is generally operated at speeds that process at least about 50 sheets of cut paper per minute. The IBM 3800 high speed laser printer, used in the Examples to illustrate high speed reprographic operations, typically processes about 180 sheets per minute. The paper sizing agent used as a surface size in this invention is a reactive sizing agent. The reactive sizing agent is preferably a 2-oxetanone sizing agent. The 2-oxetanone compound may contain a single β-lactone ring, e.g., a ketene dimer, or may contain two or more β-lactone rings, e.g., ketene multimers. The 2-oxetanone reactive sizing agent of this invention may be an alkyl ketene dimer, an alkyl ketene multimer, an alkenyl ketene dimer, an alkenyl ketene multimer, or mixtures of such dimers and/or multimers. Commercially available alkyl ketene dimer (AKD) sizing agents are typically solids at temperatures of about 20-30°C and are generally made by the dimerization of two saturated, straight-chain fatty acid chlorides, e.g., stearic acid chloride and palmitic acid chloride. The 2-oxetanone reactive sizing agent of this invention is preferably a liquid at 35 °C, i.e., it is not a solid at 35 °C, preferably is a liquid at 25 °C, and is also preferably a liquid at 20°C. Those 2-oxetanone compounds having these desirable non-solid (liquid) characteristics at the specified temperatures are generally characterized by containing hydrocarbon substituents with irregularities that may be branched alkyl, linear alkenyl or branched alkyl. Such liquid 2- oxetanone compounds generally are mixtures of compounds that contain a significant percentage, e.g., at least about 25 wt%, more preferably at least about 50 wt% and most preferably at least about 75 wt%, of 2-oxetanone which is liquid at 35 °C (preferably 25 °C or preferably 20°) containing at least one hydrocarbon substituent with an irregularity in the chemical structure of these substituents, such as branching and/or carbon to carbon double bonds, i.e., unsaturation. Such liquid 2-oxetanone compounds may be ketene dimers, ketene multimers or mixtures of these. A general structure of a 2-oxetanone compound useful as a reactive sizing agent is as follows: - 6 - in which formula n can be 0 (e.g., a ketene dimer) or n can be 1 or more ( e.g., a ketene multimer), preferably n being 1 to about 20 and more preferably n being at least 1 to about 8. Ketene multimers are typically mixtures, and mixtures of the 2-oxetanone multimers typically contain regio isomers of such multimer compounds and typically contain an average n of from about 1 to about 8. Such mixtures of 2-oxetanone multimers may also contain some 2- oxetanone dimers, i.e., n equals 0 in the general formula noted above, which is a consequence of the preparation method conventionally used to make 2-oxetanone multimers. The 2-oxetanone dimers and multimers may be prepared from reaction of a monoacid component, e.g., a fatty acid, and a diacid component, e.g., a dicarboxylic acid. In the general formula for 2-oxetanone dimers and multimers, R and R" are substantially hydrophobic in nature and may be the same or different. They are typically acyclic and are preferably hydrocarbons of at least about 4 carbon atoms in length, preferably about C JQ - C20 and are preferably independently selected from the group of straight (linear) or branched alkyl or straight (linear) or branched alkenyl hydrocarbon substituents. R' is preferably a straight chain alkyl, with about C 2 - C j 4 being more preferred and about C4 - C § being most preferred. R' may also be alicyclic (linear, branched or cyclic) having 28-40 carbon atoms, typically being derived from a C32 - C44 dicarboxylic acid. Ketene multimers useful in this invention made be made by conventional methods, e.g., from the reaction of a fatty acid or other monocarboxylic acid with a dicarboxylic acid. Reactive sizing agents based on 2-oxetanone compounds and their preparation are well known in the paper sizing art. The 2-oxetanone sizing agents used in this invention, including the preferred liquid 2-oxetanone compounds, may be made by conventional methods, such as those described for solid ketene multimers in U.S. Patent 5,685,815 of Bottorff et al., the disclosure of which is hereby incorporated by reference. The reactive sizing agent of this invention is generally formulated as an aqueous emulsion. Such aqueous emulsions are well known in the paper sizing art and may contain from about 1 to about 50 wt% of the sizing agent active component, e.g., 2-oxetanone compound, and preferably contain about 5 to about 35 wt% of sizing agent, all percentages based on the total weight of the emulsion. Such aqueous emulsions typically contain an emulsifying agent that is generally employed in an amount in the range of about 0.1 to about 5 parts by weight, more preferably about 0.2 to about 3 parts by weight, all parts being based on the weight of the sizing agent. Such emulsions may be prepared by conventional methods, using either low shear or high shear techniques, and these procedures are well known in the papermaking art. The inorganic filler that is an essential component in the method of this invention is a finely divided inorganic material that has a relatively high surface area. The inorganic filler preferably has a particle size distribution in which the mean particle size of less than bout 10 microns, more preferably less than about 5 microns, and most preferably less than about 2 microns. The inorganic filler of this invention is preferably kaolin clay (China clay), titanium dioxide, silicon dioxide (silica, precipitated amorphous silica, and the like), bentonite (a naturally occurring sodium montmorillonite), calcium silicate (e.g., precipitated amorphous calcium silicate) or mixtures of these. Other inorganic fillers having the finely divided particle size and absorptivity characteristics of these preferred fillers may also be used. Other inorganic fillers include diatomaceous earth, sodium alumino silicates, precipitated amorphous silicates, ground calcium carbonate, precipitated calcium carbonate (pec), talc, i.e., hydrated magnesium silicate, alumina including hydrated alumina, i.e., aluminum hydroxide, diatomaceous earth, and the like. The weight ratio of inorganic filler to reactive surface size that is applied as a surface treatment of the paper being treated should be from about 0.1 : 1 to about 10:1 or higher, preferably from about 0.2: 1 to about 5:1. The precise weight ratio selected for filler to surface size generally depends on the inorganic fillers used and the physical characteristics of the inorganic filler selected. For example, kaolin clay preferably is surface applied at a weight ratio of kaolin clay to reactive surface size of at least about 0.5: 1. More preferably, the weight ratio of kaolin clay filler to surface size is at least about 1 : 1, up to about 5: 1, more preferably about 1.5: 1 to about 3: 1. For the preferred silicon dioxide and titanium dioxide fillers, the weight ratio of inorganic filler to surface size is at least about 0.5: 1, with about 1 : 1 to about 5: 1 being preferred. With bentonite as the filler, the weight ratio of bentonite to surface size is preferably at least about 0.1 : 1 , more preferably 0.2 to about 10: 1, and most preferably about 0.2:1 to about 3: 1. Addition levels of the surface size on the paper being treated are generally selected to provide the desired sizing characteristics sought for the end-use applications for such paper. Addition levels of reactive sizes such as the preferred 2-oxetanone reactive size may range from about 0.02 to about 5 kg/metric tonne, more preferably about 0.1 to about 3 kg/metric tonne and most preferably about 0.5 to about 2 kg/metric tonne of paper, all based on the weight of dry paper. These addition rates refer only to surface sizing and do not include internal size, if any, in the paper. Addition levels of the inorganic filler will depend on the addition rate of the reactive size used and are generally adjusted to provide a weight ratio of inorganic filler to surface size within the ranges specified above. The reactive size and inorganic filler are applied as a surface treatment to the paper in the method of this invention. The reactive surface size and inorganic filler are normally applied as a surface treatment to both sides of the paper being treated, but if desired surface application could be made to only one side of the paper sheet. The reactive size and the inorganic filler are preferably applied to the paper surface concurrently, e.g. , in a single operation, although the two components could alternatively be applied as separate treatments, e.g., in separate steps. A preferred method of application is by use of a conventional size press. The reactive size and inorganic filler are preferably applied to the surface of the paper being treated via a size press, with both the reactive size and the filler being introduced into the size press solution. The inorganic filler may be introduced to the size press solution (or other aqueous medium) as a dry powder or as an aqueous slurry containing the filler. Other surface application methods may also be used to apply the reactive size and the inorganic filler to the surface of the paper being treated, such as conventional coating or spraying techniques, and surface application may also be made at points other than the size press in the papermaking process, e.g., at the calender stack. After surface application of the reactive size and the inorganic filler in this invention, the surface treated paper is dried by conventional methods. The desirable characteristics of alkaline paper treated according to this invention are discussed below. The reactive sizing agents of this invention applied as a surface size may also contain or be used in combination with water soluble inorganic salts. Such water soluble inorganic salts may include a calcium halide, a magnesium halide, a sodium halide or the like. Calcium chloride, magnesium chloride and sodium chloride are particularly preferred as the water soluble inorganic salt. Other optional components conventionally used in surface sizing or surface treatment techniques may be used. Such additives conventionally used in paper making include starch, polymeric surface sizing agents, and the like. The method of this invention may be used with or without commonly used size press starches. Such size press starches may include ethylated starch, enzyme-converted starch, cationic starch, oxidized starch and pearl starch. Starch addition levels useful with this invention may range from 0 to 100 kg/metric tonne of paper, and such starch addition may be made via the size press. Polymeric surface sizing agents that may be used in combination with this invention include styrene maleic anhydride copolymers and styrene acrylates. The water-soluble inorganic salts mentioned above may be used in combination with the reactive surface size and/or inorganic filler and/or other conventional paper processing components. In one preferred embodiment a 2-oxetanone sizing agent which is liquid at 35 °C, preferably 20 °C, such as alkenyl or branched alkyl ketene dimer is used in combination with at least one other sizing agent. Useful other sizing agents include alkenyl succinic anhydride (see, e.g., U.S. Patent No. 5,766,417) and straight chain alkyl ketene dimer (see, e.g., U.S. Patent No. 5,725,731). Sizing agents comprising 2-oxetanones of different types useful in such an embodiment can be prepared by mixing fatty acids and forming the 2-oxetanones or blending 2- oxetanones. The paper used in the method of this invention is not critical and may be any paper grade that requires sizing in its normal end-use application. The present invention is intended for use with alkaline, including neutral, paper that is made by an alkaline or neutral papermaking process, and such papermaking processes are well known to those in the papermaking art. The invention is most useful with precision paper handling grades of paper, particularly alkaline fine paper. These grades include forms bond, cut size paper, also called cut sheet paper, copy paper, envelope paper, adding machine tape, and the like. The basis weight of the alkaline 2 paper used m this invention may range from about 30 to about 200 g/m and is preferably within 2 a range of about 40 to about 100 g/m . - 10 - The paper used in this invention may be made with or without conventional internal sizes being present. Internal sizing agents, if used, may be present at addition levels ranging from about 0.02 to about 4 kg/metric tonne of paper, more preferably about 0.25 to 2.5 kg/metric tonne and most preferably about 0.5 to about 2.0 kg/metric tonne of paper. Conventional internal sizes may be used and these include alkenyl succinic anhydride (ASA) sizing agents and 2-oxetanone sizing agents, e.g., alkenyl ketene dimer and multimer sizing agents being preferred, as well as other reactive and non-reactive internal paper sizing agents. Such internal paper sizes may include and/or be identical to the reactive surface sizes used in the present invention. Paper made by the method of this invention exhibits excellent paper handling performance, particularly in applications involving high speed precision conversion or high speed precision reprographic operations. Fine paper grades that require good runnability on high speed paper handling equipment may be surface treated with reactive size in the method of this invention to provide increased sizing agent efficiency, improved ink jet print quality, and a reduction of the amount of internal sizing agent added at the wet end of a paper making process. Surface application of reactive sizing agents, to reduce or eliminate the amount of internal sizing agent required for such paper, improves paper making efficiency by eliminating the associated wet end deposits from such internal sizing agents. Even moderate addition levels of reactive sizes, particularly alkenyl succinic anhydride sizing agents, can cause deposits on the paper machine, web brakes and holes in the paper. Addition levels of ASA as an internal size greater than about 1 - 1.25 kg/metric tonne are often required to meet end use sizing requirements, but such internal size additional levels generally lead to unacceptable paper machine runnability and paper quality problems. The method of the present invention reduces or eliminates the need for such internal size addition by providing for the surface treatment of paper using reactive surface sizes, to provide the desired sizing characteristics and other physical properties sought for such paper, but without compromising or deteriorating high speed convertibility and runnability for such surface-sized paper on high speed paper handling equipment. The method of the present invention permits the use of 2-oxetanone reactive sizing agents such as alkyl ketene dimers and/or multimers and alkenyl ketene dimers and/or multimers - 11 - as surface sizes, and concomitantly provides for good runnability of such surface-sized paper on high speed paper handling equipment. The method of this invention is particularly useful for 2-oxetanone reactive sizing agents that are liquids at temperatures of about 20°C to about 30°C, e.g., alkenyl ketene dimer and/or multimer sizing agents. The method of this invention permits the addition of these and other reactive 2-oxetanone sizing agents as surface sizes, e.g., via addition at the size press, to provide the desired sizing performance characteristics required for alkaline fine paper. Although use of such 2-oxetanone reactive sizes as surface treatments for paper ordinarily can lead to reduced running speeds in high speed precision converting and reprographic operations for such surface- sized paper (or, alternatively, an increase in handling problems at normal high speed operation of such equipment), the use of the inorganic filler in the method of this invention provides good runnability for such surface sized paper on high speed precision paper handling equipment. The following non-limiting Examples described below illustrate various aspects of the present invention. EXAMPLES The procedures used in the Examples are pilot scale procedures that mimic a full scale paper machine size press application. The paper in the following Examples was prepared on a pilot paper machine at Western Michigan University. A representative fine paper furnish was used with the Western Michigan University paper machine, to make a typical forms bond paper-making stock. The pulp furnish (three parts hardwood kraft pulp and one part softwood kraft pulp) was refined to 425 ml Canadian Standard Freeness (C.S.F.) using a double disk refiner. Prior to the addition of the filler to the pulp furnish, the pH (7.8 - 8.0), alkalinity (150 - 200 ppm) and hardness (100 ppm) of the paper making stock were adjusted using appropriate amounts of NaHCO3, H2SO4 and NaOH. The filler added to the pulp furnish was 10%> medium particle-size precipitated calcium carbonate, in particular, Albacar 5970 precipitated calcium carbonate (available from Specialty Minerals Inc., Bethlehem, PA) which was added at a rate of 100 kg/metric tonne and was added at the machine chest. Wet-end additions of internal sizing agents were made as follows: 2-oxetanone reactive size (i.e., alkenyl ketene dimer unless noted otherwise) was added at the second mix box at a rate of 0.47 kg/metric tonne; quaternary amine-substituted cationic starch - 12 - (STA-LOK ~ 400 starch, available from A.E. Staley Company, Decatur, Illinois) was added at the first mix box overflow at a rate of 5.0 kg/metric tonne; and alum was added at the second mix box overflow at a rate of 2.0 kg/metric tonne. Stock temperature at the Whitewater tray was controlled at 49 °C. The wet presses were set at 207 cm Hg. A drier profile that gave 2-3% moisture at the size press and 4-6% moisture at the reel was used, and the paper machine speed was 0.39 meter/sec. Approximately 20 kg/metric tonne of oxidized corn starch (GPC° D-15F corn starch, available from Grain Processing Company, Muscatine, Iowa) and 2.5 kg/metric tonne of NaCl were added at the size press (54°C, pH 7.5 - 8.0). All alkaline paper used in the Examples described below was surface treated with the starch-containing size press solution, unless noted otherwise (e.g., conventional acid paper being an exception). In addition and as described in the Examples, a 2-oxetanone reactive size and/or filler were also added at the size press, to evaluate the effect of these components on the convertibility performance of the surface treated paper. Calender pressure and reel moisture were adjusted to obtain a Sheffield smoothness of 150 flow units at the reel (column no. 2, felt side up). A 35 minute roll of paper at each paper making condition was collected and converted on a commercial forms press to two boxes of standard 8 x 1 1 " forms. Samples were also collected before and after each 35-minute roll for a determination of basis weight (generally 46 lbs/3000 sq.ft. (75 kg/1000 m 2 )) and smoothness. In order to evaluate various surface treatments and their effect in preventing difficulties in converting operations, the paper was made on the Western Michigan University pilot paper machine, converted into forms, and then printed on a IBM 3800 high speed continuous forms laser printer, as a measure of its converting performance. The converted paper was allowed to equilibrate in the printer room for at least one day prior to evaluation. Each box of paper provided an amount of paper sufficient to allow a 10-14 minute ( at 67 meters/min.) evaluation on the IBM 3800 high speed laser printer, which served as an effective testing device for determining convertibility performance for the surface-treated paper on state of the art converting equipment. In particular, the phenomenon of "billowing" gives a measurable indication of the extent of slippage on the IBM 3800 printer between the undriven roll beyond - 13 - the fuser and the driven roll above the stacker. Such billowing involves a divergence of the paper path from the straight line between the rolls, which is 2 inches (5 cm) above the base plate, causing registration errors and dropped folds in the stacker. The billowing during steady-state running time is measured as the billowing height (in inches or centimeters) above the straight line paper path after 600 seconds (10 min.) of running time. The faster and higher the sheet billows, the worse the converting performance for such paper. All samples reported in the Examples were tested in duplicate, since two boxes from each run (roll) were available for testing. Example 1 Example 1 describes the evaluation of high speed precision converting performance of paper made as described above and surface treated with a 2-oxetanone reactive size in combination with various inorganic fillers. High speed converting performance was measured using an IBM 3800 high speed laser printer, in which the maximum billowing height was determined after 10 minutes of operation using the paper being evaluated. Results of all evaluations described in this Example 1 are summarized in Table 1 below. Two baseline control examples were carried out. Control 1A was an evaluation of a prior art acid fine paper made in a conventional manner with rosin and alum as the internal size and with no surface treatment being carried out. Evaluation of the high speed converting performance for the acid fine paper of Control 1A gave a billowing maximum height after 10 minutes of 2.5 - 2.75 inches (6.4 - 7.0 cm), indicating excellent high speed runnability. Control IB, the second benchmark control, was an alkaline paper made as described above with an internal size that was an alkenyl ketene dimer added at the wet end at a rate of 0.47 kg/metric tonne of paper. This alkaline fine paper was prepared as described above on the Western Michigan University pilot paper machine. The addition rate of internal size used in the alkaline fine paper for this and subsequent Examples (0.47 kg/metric tonne) represents a relatively light internal sizing rate for the alkenyl ketene dimer used as an internal size. The internally sized alkaline paper in this Control IB was not subjected to a surface treatment with either a 2-oxetanone reactive size or an inorganic filler. Evaluation of this paper on the IBM 3800 high speed laser printer resulted in a billowing maximum height after 10 minutes of 2.5 - 2.75 inches (6.4 - 7.0 cm), the same results as obtained with the acid fine paper - 14 - in Control 1A. Without any surface size, both the internally sized acid fine paper and the internally sized alkaline fine paper gave excellent high speed converting performance, as noted above. Control IC, a third control, was carried out using the same internally sized alkaline fine paper used in Control IB but surface sized with a reactive 2-oxetanone size to demonstrate the adverse effect on high speed converting performance that results with the use of such a surface size. The internally sized alkaline paper in Control 1 C was surface treated with an alkenyl ketene dimer reactive size made from a mixture of unsaturated/branched fatty acids (the same size used to internally size the paper), applied at the size press at an addition rate of 2.5 kg/metric tonne. Evaluation of the high speed converting performance on the IBM 3800 high speed laser printer gave a billowing maximum height after 10 minutes that was in excess of 6 inches (in excess of 15 cm), indicating unacceptable high speed converting performance for this surface sized alkaline fine paper. The results of the evaluations of Control 1A, Control IB and Control IC, as well as of the other examples carried out in this Example 1, are summarized below in Table 1. In the high speed converting evaluation of Controls 1A and IB on the IBM 3800 laser printer, paper runnability was excellent and no stacker or registration errors were encountered. By contrast, Control IC surface treated with an alkenyl ketene dimer surface size gave unacceptable high speed converting performance when evaluated on the IBM 3800 laser printer, since maximum billowing height increased to more than 6 inches (more than 15 cm) after 5-6 minutes of running time, and frequent stacker and registration errors were also observed. Several examples were carried out using the internally sized alkaline paper used in Control IB, but surface treated with a combination of the alkenyl ketene dimer with an inorganic filler to demonstrate the beneficial results in high speed converting performance for such surface treated alkaline fine paper. The surface size applied in each of these examples was the same as that used in Control IC, namely, an alkenyl ketene dimer that was applied at the size press at a rate of 2.5 kg/metric tonne, the same addition rate as used in Control IC. However, each of these examples differed from Control IC in that an inorganic filler was also applied at the size press in combination with the alkenyl ketene dimer surface size treatment. - 15 - In Example 1-1 , the inorganic filler was kaolin clay, HYDRAFINE " 90 kaolin, available from J.M. Huber Corp., Edison, New Jersey, applied at an addition rate of 10 kg/metric tonne. The weight ratio of inorganic filler to surface size in this Example 1 -1 was 4: 1. Evaluation of high speed converting performance on the IBM 3800 laser printer gave a billowing maximum height after 10 minutes of 2.75 - 3.0 inches (7.0 - 7.6 cm). In Example 1-2, the inorganic filler was silicon dioxide, OPTISIL 3265 silicon dioxide, a precipitated amorphous silica, available from J.M. Huber Corp., that was applied at an addition rate of 2.5 kg/metric tonne of paper. The weight ratio of filler to surface size was 1 :1 in this Example 1-2. Evaluation of high speed converting performance gave a billowing maximum height after 10 minutes of 2.75 - 3.0 inches (7.0 - 7.6 cm). In Example 1-3, the inorganic filler was titanium dioxide, TI-PURE R-941 rutile titanium dioxide, available from E.I. duPont de Nemours & Company, Wilmington, Delaware, applied at a filler addition rate of 2.5 kg/metric tonne of paper. The weight ratio of filler to surface size in this Example 1 -3 was 1 :1. Evaluation of high speed converting performance gave a billowing maximum height after 10 minutes of 3.0 inches (7.6 cm). ® In Example 1 -4, the inorganic filler was bentonite, AQUAGEL GOLD SEAL bentonite, i.e., sodium montmorillonite, available from Baroid Corporation, Houston, Texas, applied at an addition rate of 1.0 kg/metric tonne. The weight ratio of filler to surface size in this Example 1-4 was 0.4:1. Evaluation of high speed converting performance gave a billowing maximum height after 10 minutes of 2.75 - 3.0 inches (7.0 - 7.6 cm). The surface treatments for each of these Examples 1-1 to 1-4, using preferred inorganic fillers of this invention that were surface-applied in combination with an alkenyl ketene dimer surface size, demonstrated excellent high speed converting performance that was very similar to that obtained with Control IB, which used the same alkaline fine paper but without any surface treatment. In the evaluation of high speed converting performance for Examples 1-1 to 1-4 on the IBM 3800 laser printer, billowing maximum height was significantly reduced, to a maximum of 3 inches (7.6 cm), and the number of stacker and registration errors was greatly reduced or eliminated, as compared with the unsatisfactory converting results for Control I C. This improvement in high speed converting performance for Examples 1-1 to 1-4 is remarkable, being both surprising and unexpected, when contrasted with the poor converting performance - 16 - encountered with Control IC, in which the alkaline paper was surface treated with the same reactive surface size and amount as in Examples 1-1 to 1-4 but without the presence of a surface- applied inorganic filler. Several additional Comparative Examples were also carried out in this Example, using other inorganic fillers applied at the size press but different from those used in Examples 1-1 to 1-4, that did not result in satisfactory high speed converting performance for such surface treated papers. Although these inorganic fillers provided little or no improvement in the conversion performance of the surface sized alkaline fine paper, it is believed that improvements in paper runnability could be achieved with either higher addition levels of these same inorganic fillers or use of different grades of these inorganic fillers having either a higher surface area or higher absorptivity. Comparative Examples Cl-1 to Cl-3 evaluated three types of silicate fillers at an addition rate of 2.5 kg/metric tonne of paper, so that the weight ratio of filler to surface size in each example was 1 : 1. In Comparative Examples Cl-1 and Cl-2, the inorganic fillers were respectively calcium silicate, HUBERSORB® 600 calcium silicate and HUBERSORB® 250 calcium silicate, available from J.M. Huber Corp., Edison, New Jersey. The precipitated amorphous calcium silicate in Comparative Example Cl-1 was finer in average particle size than that used in Comparative Example Cl-2. In Comparative Example Cl-3, the inorganic filler was HYDREX P precipitated amorphous silicate, available from J. M. Huber Corp., Edison, New Jersey. For each of these Comparative Examples Cl-1 to Cl-3, evaluation of high speed converting performance gave unsatisfactory results since billowing maximum height after 10 minutes was in excess of 6 inches (in excess of 15 cm). The unpredictability of using an inorganic filler as a surface treatment in combination with a reactive surface size, to provide improved paper convertibility notwithstanding the presence of the reactive surface size on the paper, is further evidenced by the following findings regarding the use of internal fillers. The present inventors have discovered that HUBERSORB 600 calcium silicate, when used as an internal filler added at a rate of 10 kg/metric tonne at the wet end of a papermaking process, improves the convertibility performance of an alkaline fine paper that is internally sized with an alkyl ketene dimer at an addition rate of 1.1 kg/metric tonne, but the comparable use of either OPTISIL® 3265 silicon dioxide or HYDREX® P - 17 - precipitated amorphous silicate as internal additives does not improve paper convertibility of alkaline fine paper containing the identical internal size (alkyl ketene dimer) at the same addition rate. Comparative Examples Cl-4 and Cl-5 evaluated calcium carbonate as the inorganic filler as a surface treatment, applied at a filler addition rate of 10.0 kg/metric tonne paper, so the weight ratio of filler to surface size was 4:1. In Comparative Example Cl-4, the inorganic filler was HYDROCARB™ 90 ground calcium carbonate, available from OMYA, Inc., Florence, Vermont, and in Comparative Example Cl-5, the inorganic filler was ALBACAR HO precipitated calcium carbonate, available from Specialty Minerals Inc., New York, New York. Evaluation of high speed converting performance gave unsatisfactory results, with billowing maximum height being in excess of 6 inches (in excess of 15 cm) for both Comparative Examples. Comparative Example Cl-6 evaluated alumina as the inorganic filler, applied at an addition rate of 2.5 kg/metric tonne paper so that the weight ratio of filler to surface size was 1:1. The inorganic filler was HYDRAL 710 alumina, available from Alcoa Alumina and Chemicals, LLC, Pittsburgh, Pennsylvania. In Comparative Example Cl-7, the inorganic filler was talc, i.e., magnesium silicate, applied at an addition rate of 10.0 kg/metric tonne so that the weight ratio of filler to surface size was 4:1. The inorganic filler in this Comparative Example Cl-7 was VANTALC 6H talc, available from R.T. Vanderbilt Company, Inc., Norwalk, Connecticut. High speed converting performance for both Comparative Examples Cl-6 and Cl-7 was unacceptable, the billowing maximum height after 10 minutes being in excess of 6 inches (in excess of 15 cm). TABLE 1 SO tΛ Surface Treatment Billowing Maximum Example Comments Height (inches (cm)) After 10 Minutes Alkenyl Filler Filler Weight Ketene Addition Rate Ratio of Dimer (kg / metric tonne) Filler : Addition Surface Size Rate (kg / metric tonne) Control 1 A none none 0 2.5 - 2.75 acid fine paper; (6.4 - 7.0) with rosin & alum internal size Control IB none none 0 2.5 - 2.75 alkaline paper (6.4 - 7.0) with internal size* o Control I C 2.5 none 0 6 + H (15+) Vι 4-- o\ VO Surface Treatment in Example Billowing Maximum Comments Height (inches (cm)) After 10 Minutes Alkenyl Filler Filler Weight Ketene Addition Rate Ratio of Dimer (kg / metric tonne) Filler : Addition Surface Size Rate (kg/ metric tonne) 1 - 1 2.5 kaolin 10.0 4: 1 2.75-3.0 (HYDRAFINE 90) (7.0 - 7.6) 1 -2 2.5 silicon dioxide 2.5 1 : 1 2.75-3.0 (OPTISIL^ 3265) (7.0 - 7.6) 1 -3 2.5 titanium dioxide 2.5 1 : 1 3.0 (TI-PURE' R-941) (7.6) 1 -4 2.5 bentonite 1.0 0.4: 1 2.75-3.0 (AQUAGE GOLD (7.0 - 7.6) SEAL ) O H O Comparative 2.5 calcium silicate 2.5 1 : 1 6 + alkaline paper Cl -1 (HUBERSORB' 600) (15+) with internal size* Surface Treatment in Billowing Maximum Example Comments Height (inches (cm)) After 10 Minutes Alkenyl Filler Filler Weight 0) Ketene Addition Rate Ratio of c Dimer (kg / metric tonne) Filler : 00 in Addition Surface Size Rate (kg / metric tonne) o x m Comparative 2.5 calcium silicate 2.5 1 : 1 6 + q Cl - 2 (HUBERSO 250) (15+) 33 c Comparative 2.5 precipitated 2.5 1 : 1 6 + m Cl - 3 amorphous silicate (15+) (HYDREX- P) Comparative 2.5 ground 10.0 4 : 1 6 + Cl - 4 calcium carbonate (15+) (HYDROCARB" 90) Comparative 2.5 precipitated 10.0 4 : 1 6 + O Cl - 5 calcium carbonate (15+) (ALBACAR- HO) 1 Λ so so Comparative 2.5 alumina 2.5 1 : 1 6 + Cl - 6 (HYDRAL" 710) (15+) as VO Surface Treatment 4-. Example Billowing Maximum Height (inches (cm)) Comments After 10 Minutes Alkenyl Filler Filler Weight Ketene Addition Rate Ratio of Dimer (kg / metric tonne) Filler : Addition Surface Size Rate (kg / metric tonne) Comparative 2.5 talc 10.0 4 : 1 6 + Cl - 7 (magnesium (15+) silicate) (VANTALC 6H) alkenyl ketene dimer @ 0.47 kg / metric tonne paper o H VO - 22 - Example 2 Example 2 evaluates the effect on high speed converting performance of an alkaline fine paper that is surface-treated with various amounts of an alkenyl ketene dimer reactive surface size used in combination with kaolin clay as the inorganic filler, both applied at various addition rates and weight ratios of filler to surface size. The paper used in this Example was alkaline paper that had been internally sized with an alkenyl ketene dimer at an addition rate of 0.47 kg/metric tonne of paper, the same internally sized alkaline fine paper used in Control IB of Example 1. The 2-oxetanone reactive size was an alkenyl ketene dimer sizing agent, and this reactive size was the same as that used in Example 1. The inorganic filler used in this Example 2 ® was HYDRAFINE 90 kaolin clay, available from J.M. Huber Corporation, Edison, New Jersey, and this kaolin clay is a fine particle size clay having a particle size distribution in which 90-96 wt% is finer than 2 microns in size. Although the kaolin clay used in this Example 2 was a dry powder, an aqueous slurry of kaolin clay is preferable in commercial practice. Results of all evaluations described in this Example 2 are summarized in Table 2 below. Two controls, Control 2A and Control 2B, were carried out using a surface treatment of alkenyl ketene dimer alone, applied at the size press at an addition rate of 1.75 kg/metric tonne of paper without any inorganic filler being surface applied. Evaluation of high speed converting performance on the IBM 3800 laser printer resulted in billowing maximum height after 10 minutes being 4.0 - 6.0 inches (10.1 - 15.2 cm) for Control 2A and 3.0 inches (7.6 cm) for Control 2B. Examples 2-1 to 2-3 were carried out using the same reactive surface size and addition rate but with the concurrent surface treatment at the size press of the kaolin filler at three different addition rates: 2.5, 5 and 10 kg/metric tonne paper, such that the weight ratio of filler to surface size was respectively 1.4: 1 , 2.8: 1, and 5.7: 1. Evaluation of the high speed converting performance for each of these three Examples showed that the surface treated paper gave excellent performance, in which billowing maximum height after 10 minutes in all cases was only 2.75 inches (7.0 cm). In the next set of evaluations in this Example 2, the addition rate of alkenyl ketene dimer surface size was increased to 2.5 kg/metric tonne paper (as compared with 1.75 kg/metric tonne in the first group described above). Three controls, Controls 2C, 2D and 2E, were carried out using the alkenyl ketene dimer applied at the size press at the specified 2.5 kg/metric tonne addition rate but without any concurrent surface treatment with an inorganic filler. Evaluation of - 23 - high speed converting performance showed that the reactive size surface-treated alkaline paper for Controls 2C, 2D and 2E gave generally poor results, with billowing maximum height after 10 minutes being 5.0 inches (12.7 cm) for Control 2C, 4.0 - 6.0 inches (10.1 - 15.2 cm) for Control 2D and in excess of 6 inches (in excess of 15 cm) for Control 2E. In Examples 2-4 and 2-5, surface treatment of the alkaline paper with the alkenyl ketene dimer sizing agent at a rate of 2.5 kg/metric tonne also included the concurrent surface application at the size press of HYDRAFLNE 90 kaolin clay at two different addition rates: 3.75 kg/metric tonne in Example 2-4, giving a weight ratio of filler to surface size of 1.5:1, and 5 kg/metric tonne in Example 2-5, giving a weight ratio of filler to surface size of 2: 1. High speed converting performance was generally satisfactory for Example 2-4, in which billowing maximum height after 10 minutes was 3.0 - 3.25 inches (7.6 - 8.2 cm), and significantly improved for Example 2-5 in which the kaolin filler addition rate was 5 kg/metric tonne instead of 3.75 kg/metric tonne . Billowing maximum height measured for Example 2-5 was 2.75 inches (7.0 cm), indicating excellent high speed converting performance. In the next evaluation grouping in Example 2, the addition rate of the alkenyl ketene dimer surface size was increased still further, to 3.75 kg/metric tonne paper. In Control 2-F, the alkenyl ketene dimer was surface applied at an addition rate of 3.75 kg/metric tonne without the concurrent surface application of an inorganic filler. Evaluation of the high speed converting performance for this Control 2F gave a billowing maximum height that was in excess of 6 inches (in excess of 15 cm), indicating unacceptable paper runnability. In Example 2-6, the alkenyl ketene dimer surface size and kaolin clay filler were each surface-applied at the size press at identical respective rates of 3.75 kg/metric tonne, giving a weight ratio of filler to surface size of 1 : 1. High speed converting performance for this surface treated alkaline paper was marginally improved over that of Control 2F, with billowing maximum height after 10 minutes being 4.5 - 6 inches (1 1.4 - 15.2 cm). In Example 2-7, the addition rate of kaolin clay filler was increased from 3.75 kg/metric tonne (used in Example 2-6) to 5 kg/metric tonne so that the weight ration of filler to surface size was 1.3:1 in this Example 2-7. The high speed converting performance measured for this Example 2-7 was inexplicably unsatisfactory, being in excess of 6 inches (in excess of 15 cm) maximum billowing height after 10 minutes. - 24 - In Example 2-8, the addition rate of kaolin clay filler was increased further, as compared with Examples 2-6 and 2-7, to 7.5 kg/metric tonne. The weight ratio of filler to surface size in this Example 2-8 was therefore 2: 1, and this relative amount of kaolin filler to surface size provided excellent high speed converting performance. Billowing maximum height after 10 minutes measured for this Example 2-8 was 2.75 inches (7.0 cm), indicating excellent paper runnability for this surface-treated alkaline fine paper. In the last evaluation grouping for Example 2, the addition rate at the size press of alkenyl ketene dimer surface size was increased to 5 kg/metric tonne of paper, and two different addition rates of HYDRAFINE 90 kaolin clay were evaluated. In Comparative Example C2-1, the kaolin filler addition rate was 3.75 kg/metric tonne, giving a weight ratio of filler to surface size of 0.75 : 1. High speed converting performance measured for this Comparative Example C2- 1 was unsatisfactory, billowing maximum height after 10 minutes being in excess of 6 inches (in excess of 15 cm). In Example 2-9, the addition rate of kaolin filler was twice that used in Comparative Example C2-1, being 7.5 kg/metric tonne of paper, which provided a weight ratio of filler to surface size of 1.5:1. High speed converting performance measured for this Example 2-9 was good, with billowing maximum height after 10 minutes being 3.0 - 3.25 inches (7.6 - 8.2 cm). These results, which are summarized in Table 2 shown below, demonstrate that use of a surface-applied kaolin filler with the alkenyl ketene dimer reactive surface size provides excellent results in high speed converting performance when the weight ratio of the kaolin clay filler to alkenyl ketene dimer surface size is in excess of 1 : 1. The results in this Example likewise demonstrate that optimal cost-effective high speed converting performance is obtained for alkaline fine paper surface sized with an alkenyl ketene dimer when the weight ratio of inorganic kaolin clay filler to surface size is about 1.5 - 3: 1. Weight ratios of the kaolin clay filler to surface size in excess of 3:1 also provide excellent high speed converting performance but do not appear to be cost effective since weight ratios in the range of 1.5 - 3:1 would give similar excellent results. \o TABLE 2 tΛ Surface Treatment Billowing Example Comments Maximum Height CO (inches (cm)) c σ After 10 Minutes W H Alkenyl Kaolin Filler Weight Ratio of Ketene Dimer (HYDRAFINE 0 90) Filler : Surface (0 Addition Rate Addition Rate Size X m (kg / metric tonne) (kg / metric tonne) q Control 2A 1.75 none 4.0-6.0 alkaline paper 3 c (10.1 - 15.2) with internal m size* ι O) Control 2B 1.75 none 3.0 (7.6) 2- 1 1.75 2.5 1.4: 1 2.75 (7.0) 2-2 1.75 5 2.8: 1 2.75 (7.0) 0 n 2-3 1.75 10 5.7: 1 2.75 (7.0) Control 2C 2.5 none 5.0 (12.7) Control 2D 2.5 none 4.0-6.0 (10.1 - 15.2) Surface Treatment in Example Billowing Comments Maximum Height (inches (cm)) After 10 Minutes CO Alkenyl Kaolin Filler Weight Ratio of c σ Ketene Dimer (HYDRAFINE 0 90) Filler : Surface to Addition Rate Addition Rate Size (kg / metric tonne) (kg / metric tonne) Control 2E 2.5 none 6+ (15+) to CO X 2-4 2.5 3.75 1.5: 1 3.0-3.25 (7.6-8.2) m 3 2-5 2.5 5 2: 1 2.75 (7.0) c Control 2F 3.75 none 6+ (15+) m M 2-6 3.75 3.75 1 : 1 4.5-6.0 (11.4-15.2) 2-7 3.75 5 1.3 : 1 6+ (15+) 2-8 3.75 7.5 2: 1 2.75 (7.0) Comparative 5.0 3.75 0.75 : 1 6+ (15+) n H C2-1 05 2-9 5.0 7.5 1.5: 1 3.0-3.25 (7.6-8.2) alkenyl ketene dimer @ 0.47 kg/metric tonne paper ON - 27 - Example 3 Example 3 describes another evaluation of high speed converting performance of alkaline paper made as described above and surface treated with a 2-oxetanone reactive size in combination with various inorganic fillers. Results of all evaluations described in this Example 3 are summarized in Table 3 below. Several baseline control examples were carried out. Control 3 A was an evaluation of a prior art acid fine paper made in a conventional manner with rosin and alum as the internal size and with no surface treatment being carried out. Evaluation of high speed convertibility performance of the acid fine paper in Control 3 A using the IBM high speed printer gave a billowing maximum height after 10 minutes of 2.5 - 2.75 inches (6.4 - 7.0 cm), indicating excellent performance. Control 3B, the second benchmark control, was an alkaline fine paper made as described above on the Western Michigan University pilot paper machine with an internal size that was an alkenyl ketene dimer added at the wet end at a rate of 0.47 kg/metric tonne of paper. This internally sized alkaline paper was not subjected to a surface treatment with either a 2-oxetanone reactive surface size or an inorganic filler. Evaluation of this alkaline fine paper for converting performance gave excellent results, identical to that obtained with the acid fine paper in Control 3A. Without any surface size, both the internally sized acid fine paper and the internally sized alkaline fine paper provided excellent high speed converting performance. Control 3C was a third control that was carried out using the same internally sized alkaline fine paper used in Control 3B, but surface sized with a reactive 2-oxetanone size to demonstrate the adverse effect on high speed converting performance that results with the use of such a surface size. The internally sized alkaline paper used in Control 3C was surface-treated with the same size used to internally size the paper, i.e., an alkenyl ketene dimer reactive size, and that was applied at the size press at an addition rate of 1.0 kg/metric tonne. In a similar fashion, Controls 3D and 3E were likewise surface-treated with the same alkenyl ketene dimer reactive size applied at higher addition rates, 1.75 and 2.5 kg/metric tonne, respectively. Evaluation of the high speed converting performance on the IBM 3800 high speed laser printer for controls 3C, 3D and 3E gave the following billowing maximum height after 10 minutes: 2.75 inches (7.0 cm); 4 - 6 inches (10.1 - 15.2 cm); and 5.0 inches (12.7 cm). The results of the convertibility performance evaluations of Control 3C, Control 3D and Control 3E demonstrate that as the surface-applied concentration of an alkenyl ketene dimer surface size is increased, high speed converting performance becomes progressively worse. - 28 - Several Examples were carried our using the internally sized alkaline paper used in Control 3E, but surface-treated with a combination of alkenyl ketene dimer with an inorganic filler to demonstrate the beneficial results in high speed converting performance for such surface-treated alkaline fine paper. The surface size applied in each of these Examples was the same as that used in Control 3E, namely, the alkenyl ketene dimer that was applied at a rate of 2.5 kg/metric tonne. However, each of these Examples differed from Control 3E in that an inorganic filler was applied, as described below, in combination with the alkenyl ketene dimer that was also applied as a surface treatment at the size press. In Comparative Example C3-1, the inorganic filler was calcium silicate, HUBERSORB 600 calcium silicate, available from J.M. Huber Corp., Edison, New Jersey, applied at an addition rate of 1.5 kg/metric tonne. The weight ratio of inorganic filler to surface size in comparative Example C-l was 0.6: 1. The evaluation of high speed converting performance on the IBM 3800 laser printer gave a billowing maximum height after 10 minutes of 6 inches (15.2 cm), indicating poor paper runnability. In Example 3-1, the same inorganic filler was used, i.e., HUBERSORB 600 calcium silicate, but the filler addition rate in this surface treatment was increased to 2.5 kg/metric tonne, as compared to 1.5 kg/metric tonne in Comparative Example C3-1. The weight ratio of filler to surface size in this Example 3-1 was 1 : 1. Evaluation of high speed converting performance gave a billowing maximum height after 10 minutes of 2.75 - 3.0 inches (7.0 - 7.6 cm), indicating excellent paper runnability. At the addition rate and weight ratio of filler to surface size used in Example 3-1, the calcium silicate inorganic filler eliminated the paper billowing and runnability problems caused by the presence of the alkenyl ketene dimer surface size. The positive effect and improvement in paper convertibility at the filler addition rate and weight ratio of filler to surface size used in this Example 3-1 contrast with the results obtained with Comparative Example C3-1 in which lower levels of calcium silicate provided little or no beneficial effect on paper runnability. The poor paper convertibility results obtained with Comparative Example Cl-1 in Example 1, which also used HUBERSORB calcium silicate at similar levels to those used in Example 3- 1 , indicate that a 1 : 1 weight ratio of filler to surface size should be increased, e.g. , to a weight ratio in excess of 1 : 1, to assure consistent improvement in paper convertibility from this - 29 - surface-applied inorganic filler at the addition rate of alkenyl ketene dimer used in these Examples. In Examples 3-2 to 3-4, the inorganic filler was a kaolin clay, HYDRAFΓNE 90 kaolin clay, available from J.M. Huber Corp., Edison, New Jersey, applied at three different addition rates, namely, 2.5, 5.0 and 10.0 kg/metric tonne, respectively. Since the addition rate of alkenyl ketene dimer that was likewise applied as a surface treatment in these three Examples was 2.5 kg/metric tonne, the respective weight ratios of filler to surface size in Examples 3-2 to 3-4 were 1:1, 2:1 and 4: 1. Evaluations of high speed converting performance on the IBM 3800 laser printer demonstrated excellent convertibility performance for Examples 3-3 and 3-4, as compared with Example 3-2 which gave only fair convertibility performance. Billowing maximum heights measured after 10 minutes for Examples 3-2 to 3-4 were 4 inches (10.1 cm); 3 inches (7.6 cm); and 2.5 - 3 inches (7.0 - 7.6 cm), respectively. These results, all of which are summarized in Table 3 below, demonstrate that weight ratios of kaolin clay filler to surface size above a ratio of about 1 : 1 provide excellent paper convertibility performance for an alkenyl ketene dimer applied as a surface size at an addition rate of 2.5 kg/metric tonne for the internally sized alkaline paper used in this Example 3. TABLE 3 Example Billowing Maximum Comments Surface Treatment Height (inches (cm)) After 10 Minutes Alkenyl Ketene Dimer Filler Filler Weight Ratio of Addition Rate Addition Rate Filler : Surface (kg / metric tonne) (kg / metric Size tonne) Control 3A none none 0 2.5 - 2.75 acid fine paper (6.4 - 7.0) with rosin & © alum internal size Control 3B none none 0 2.75 (7.0) alkaline paper with internal size* Control 3C 1.0 none 0 2.75 (7.0) Control 3D 1.75 none 0 4 0 - 6 0 (10.1 - 15 2) Control 3E 2.5 none 0 5.0 (12.7) Comparative 2 5 calcium silicate 1 5 0.6 : 1 6.0 *3 o C3-1 (HUBERSORB 0 600) (15.2) 3-1 2.5 calcium silicate 2.5 1 • 1 2.75 - 3 0 (HUBERSORB® 600) (7.0 - 7.6) 3-2 2.5 kaolin clay 2.5 1 : 1 4.0 (HYDRAFINE 0 90) (10.1) o Example \o Billowing Maximum Comments Surface Treatment Height (inches (cm)) tΛ After 10 Minutes Alkenyl Ketene Dimer Filler Filler Weight Ratio of Addition Rate Addition Rate Filler : Surface (kg / metric tonne) (kg / metric Size tonne) 3-3 2.5 kaolin clay 5.0 2 : 1 3.5 (8.9) (HYDRAFINE 0 90) 3-4 2.5 kaolin clay 10.0 4 : 1 2.75 - 3.0 (HYDRAFINE 0 90) (7.0 - 7.6) alkenyl ketene dimer @ 0.47 kg / metric tonne paper o H t/3 - 32 - Example 4 Example 4 describes the evaluation of high speed converting performance of paper made as described above and surface treated with a 2-oxetanone reactive size that was an alkyl ketene dimer, rather than the alkenyl ketene dimer used in the previous Examples. The alkyl ketene dimer was based on C^-C j saturated fatty acids (palmitic and stearic acids) that was applied as a surface treatment to alkaline fine paper at an addition rate of 1.0 kg/metric tonne. Two baseline control examples were carried out. Control 4A was an evaluation of a prior art acid fine made in a conventional manner with rosin and alum as the internal size and with no surface treatment being carried out. Control 4A using this acid fine paper gave a billowing maximum height after 10 minutes of 2.5 - 2.75 inches (6.4 - 7.0 cm), indicating generally excellent paper runnability for this prior art fine paper. Control 4B, the second benchmark control, was an alkaline paper made as described above on the Western Michigan University pilot paper machine with an internal size that was an alkenyl ketene dimer (not an alkyl ketene dimer) added at the wet end at a rate of 0.47 kg/metric tonne of paper. This internally sized alkaline fine paper was also surface sized with a reactive 2- oxetanone size, i.e., the above-mentioned alkyl ketene dimer, to demonstrate the adverse effect on high speed converting performance that results with the use of such an alkyl ketene dimer surface size. The alkyl ketene dimer reactive size was applied to the paper surface using the size press at an addition rate of 1.0 kg/metric tonne. Evaluation of the high speed converting performance of this surface sized alkaline fine paper on the IBM 3800 high speed laser printer gave a billowing maximum height after 10 minutes that was 3.5 inches (8.9 cm) and also caused a long loop error. Example 4-1 was carried out using the internally sized alkaline paper used in Control 4B, but surface-treated with a combination of the alkyl ketene dimer with an inorganic filler to demonstrate the beneficial results in high speed converting performance for such surface treated alkaline fine paper. The inorganic filler was kaolin clay, HYDRAFINE 90 kaolin clay, available from J.M. Huber Corp., Edison, New Jersey, applied at an addition rate of 10.0 kg/metric tonne. Since the addition rate of the alkyl ketene dimer at the size press was 1.0 kg/metric tonne, the weight ratio of filler to surface size was 10: 1 in this Example 4-1. Evaluation of high speed converting performance gave a billowing maximum height after 10 - 33 - minutes of 2.75 inches (7.0 cm), indicating excellent paper runnability similar to that obtained for the acid fine paper in Control 4A. The results obtained in Example 4-1 demonstrate that the ® addition of HYDRAFINE 90 kaolin clay at a weight ratio of filler to surface size of 10: 1 eliminated the billowing caused by the surface-applied alkyl ketene dimer. The method of this invention is thus applicable to alkyl ketene dimers, such as those made from mixtures of saturated fatty acids. For illustrative purposes, Control 4C is included in this Example 4 to demonstrate that the presence of moderate-to-heavy amounts of an alkyl ketene dimer as an internal size in an alkaline fine paper causes the paper's convertibility performance to deteriorate. This is shown by a billowing maximum height of 3.25 inches (8.2 cm) that resulted with the internal addition at the wet end of alkyl ketene dimer, made from a mixture of C^-C j g saturated fatty acids (palmitic and stearic acids), added at a rate of 1.1 kg/metric tonne. No surface treatments of surface size and/or inorganic filler were made to this internally-sized paper. TABLE 4 Surface Treatment Billowing Maximum Example Comments Height (inches (cm)) After 10 Minutes -fc. Alkyl Filler Weight Ratio Ketene Dimer Filler Addition Rate (kg of Filler : Addition Rate / metric tonne) (kg / metric tonne) Surface Size acid fine paper Control 4A none none 0 2.5 - 2.75 with rosin & alum (6.4 - 7.0) internal size Control 4B 1.0 none 0 3.5 (8.9) alkaline paper with o long loop error internal size* 4-1 1.0 kaolin clay 10.0 10 : 1 2.75 (7.0) 4-. (HYDRAFINE 0 90) Surface Treatment Billowing Example Maximum Comments Height (inches (cm)) After 10 Minutes Alkyl Filler Ketene Dimer Filler Weight Ratio Addition Rate (kg of Filler : Addition Rate / metric tonne) (kg / metric tonne) Surface Size alkaline paper with Control 4C none none 3.25 (8.2) 0 internal size** * alkenyl ketene dimer @ 0.47 kg / metric tonne paper ** alkyl ketene dimer @ 1.1 kg / metric tonne paper n so o - 36 - Example 5 Example 5 evaluates the effect on high speed converting performance of an alkaline fine paper that is surface-treated with various amounts of an alkenyl ketene dimer reactive surface size used in combination with bentonite as the inorganic filler, both applied at various addition rates and weight ratios of filler to surface size. The inorganic filler used in this Example 5 was VOLCLAY HPM 75 bentonite clay, available from Amcol International Corporation, Arlington Heights, Illinois. Results of all evaluations described in this Example 5 are summarized in Table 5 below. Three baseline control examples were carried out. Control 5 A was an evaluation of a prior art acid fine paper made in a conventional manner with rosin and alum as the internal size and with no surface treatment being carried out. Evaluation of the high speed converting performance for the acid fine paper of Control 5 A gave a billowing maximum height after 10 minutes of 2.5 - 2.75 inches (6.4 - 7.0 cm), indicating excellent high speed runnability. Control 5B, the second benchmark control, was an alkaline paper made with an internal size that was an alkenyl ketene dimer added at the wet end at a rate of 0.47 kg/metric tonne of paper, and this alkaline fine paper was essentially the same as that described in Example 1 as Control IB. The internally sized alkaline paper in this Control 5B was not subjected to a surface treatment with either a 2-oxetanone reactive size or an inorganic filler. Evaluation of this paper on the IBM 3800 high speed laser printer resulted in a billowing maximum height after 10 minutes of 2.75 inches (7.0 cm), similar to the results obtained with the acid fine paper in Control 5A. Without any surface size, both the internally sized acid fine paper and the internally sized alkaline fine paper gave excellent high speed converting performance, as noted above. Control 5C, a third control, was carried out using the same internally sized alkaline fine paper used in Control 5B but surface sized with a reactive 2-oxetanone size to demonstrate the adverse effect on high speed converting performance that results with the use of such a surface size. The internally sized alkaline paper in Control 5C was surface treated with the same alkenyl ketene dimer reactive size used in Examples 1-3 (and the same size was used to internally size the paper), applied at the size press at an addition rate of 2.5 kg/metric tonne. Evaluation of the high speed converting performance on the IBM 3800 high speed laser printer gave a billowing maximum height after 10 minutes that was in excess of 6 inches (in excess of 37 15 cm), indicating unacceptable high speed converting performance for this surface sized alkaline fine paper. The results of the evaluations of Control 5 A, Control 5B and Control 5C, as well as of the other examples carried out in this Example 5, are summarized below in Table 5. In the high speed converting evaluation of Controls 5A and 5B on the IBM 3800 laser printer, paper runnability was excellent and no stacker or registration errors were encountered. By contrast, Control 5C surface treated with an alkenyl ketene dimer surface size gave unacceptable high speed converting performance when evaluated on the IBM 3800 laser printer, since maximum billowing height increased to more than 6 inches (more than 15 cm)and frequent long loop errors were encountered. Comparative Example C5-1 and Examples 5-1 and 5-2 were carried out using the same reactive surface size and addition rate but with the concurrent surface treatment at the size press of the bentonite filler at three different addition rates: 0.25, 0.5 and 1.0 kg/metric tonne paper, such that the weight ratio of filler to surface size was respectively 0.1 : 1, 0.2: 1, and 0.4: 1. High speed converting performance measured on the IBM 3800 laser printer for Comparative Example C5-1 was unsatisfactory, with the billowing maximum height after 10 minutes being in excess of 6 inches (in excess of 15 cm). In Example 5-1, the addition rate of bentonite filler was twice that used in Comparative Example C5-1, being 0.5 kg/metric tonne of paper, which provided a weight ratio of filler to surface size of 0.2: 1. High speed converting performance measured for this Example 5-1 was good, with billowing maximum height after 10 minutes being 3.5 inches (8.9 cm). In Example 5-2, the addition rate of bentonite filler was twice that used in Example 5-1 (and four times that used in Comparative Example C5-1), being 1.0 kg/metric tonne of paper, which provided a weight ratio of filler to surface size of 0.4: 1. High speed converting performance measured for this Example 5-1 was excellent, with billowing maximum height after 10 minutes being 2.75 inches (7.0 cm), equivalent to that obtained with benchmark Control 5B which was alkaline paper that contained no surface size and no surface filler. In the next set of evaluations in this Example 5, the addition rate of alkenyl ketene dimer surface size was increased to 3.75 kg/metric tonne paper (as compared with 2.5 kg/metric tonne in the first group described above). In Comparative Example C5-2, surface treatment of the alkaline paper with the alkenyl ketene dimer sizing agent at a rate of 3.75 kg/metric tonne also included the concurrent surface application at the size press of VOLCLAY ' 90 bentonite clay at 38 an addition rate of 0.25 kg/metric tonne, giving a weight ratio of filler to surface size of 0.07: 1. High speed converting performance was unacceptable for Comparative Example C5-2, in which billowing maximum height after 10 minutes was in excess of 6 inches (in excess of 15 cm). In Examples 5-3 and 5-4, surface treatment of the alkaline paper with the alkenyl ketene dimer sizing agent was at a rate of 3.75 kg/metric tonne (as in Comparative Example C5-2) but ® with the concurrent surface application at the size press of VOLCLAY 90 bentonite clay at two higher addition rates: 0.5 kg/metric tonne in Example 5-3, giving a weight ratio of filler to surface size of 0.13: 1, and 1.0 kg/metric tonne in Example 5-4, giving a weight ratio of filler to surface size of 0.27: 1. High speed converting performance was generally satisfactory for Example 5-3, in which billowing maximum height after 10 minutes was 3.75 inches (9.5 cm), and further improved for Example 5-4 in which the bentonite filler addition rate was 1.0 kg/metric tonne instead of 0.5 kg/metric tonne . Billowing maximum height measured for Example 5-4 was 3.0 inches (7.6 cm), indicating good high speed converting performance. In the last set of evaluations in this Example 5, the addition rate of alkenyl ketene dimer surface size was increased to 5.0 kg/metric tonne paper (as compared with 3.75 kg/metric tonne in the previous group described above). In Comparative Examples C5-3 and 5-4, surface treatment of the alkaline paper with the alkenyl ketene dimer sizing agent at a rate of 5.0 kg/metric tonne also included the concurrent surface application at the size press of VOLCLAY 90 bentonite clay at two different addition rates: 0.25 kg/metric tonne in Comparative Example C5-3, giving a weight ratio of filler to surface size of 0.05: 1, and 0.5 kg/metric tonne in Comparative Example C5-4, giving a weight ratio of filler to surface size of 0.1 : 1. High speed converting performance was unacceptable for each of Comparative Examples C5-3 and C5-4, in which billowing maximum height after 10 minutes was in excess of 6 inches (in excess of 15 cm) for both. In Examples 5-5 and 5-6, surface treatment of the alkaline paper with the alkenyl ketene dimer sizing agent was again at a rate of 5.0 kg/metric tonne (as in Comparative Example C5-3 ® and C5-4) but with the concurrent surface application at the size press of VOLCLAY 90 bentonite clay at two higher addition rates: 1.0 kg/metric tonne in Example 5-5, giving a weight ratio of filler to surface size of 0.2: 1, and 1.5 kg/metric tonne in Example 5-6, giving a weight ratio of filler to surface size of 0.3 : 1. High speed converting performance was generally satisfactory for Example 5-5, in which billowing maximum height after 10 minutes was 3.5 inches (8.9 cm), and significantly improved for Example 5-6 in which the bentonite filler 39 addition rate was 1.5 kg/metric tonne instead of 1.0 kg/metric tonne . Billowing maximum height measured for Example 5-6 was 2.75 inches (7.0 cm), indicating excellent high speed converting performance, equivalent to that obtained with benchmark Control 5B which was alkaline paper that contained no surface size and no surface filler. The results for this Example 5, which are summarized in Table 5 shown below, demonstrate that use of a surface-applied bentonite filler with the alkenyl ketene dimer reactive surface size provides satisfactory results in high speed converting performance when the weight ratio of the bentonite clay filler to alkenyl ketene dimer surface size is in excess of 0.1 : 1. The results in this Example likewise demonstrate that optimal cost-effective high speed converting performance is obtained for alkaline fine paper surface sized with an alkenyl ketene dimer when the weight ratio of inorganic bentonite clay filler to surface size is about 0.2:1 to about 0.4:1. Weight ratios of the bentonite clay filler to surface size in excess of 0.4:1 would also provide excellent high speed converting performance but do not appear to be cost effective since weight ratios in the preferred range of about 0.2:1 to about 0.4:1 would give good results. TABLE 5 SO SO 1 ≥ in Surface Treatment Example Billowing Comments Maximum Height (inches (cm)) After 10 Minutes Alkenyl Bentonite Filler Weight Ratio of Ketene Dimer (VOLCLAY- HPM 75) Filler : Surface 4^ Addition Rate Addition Rate Size O (kg / metric tonne) (kg / metric tonne) Control 5A none none 2.5 - 2.75 acid fine paper (6.4 - 7.0) with rosin & alum internal size Control 5B none none 2.75 (7.0) alkaline paper with internal size* Control 5C 2.5 none 6+ (15+) long loop error Comparative C5-1 2.5 0.25 0.1 : 1 6+ (15+) 5-1 2.5 0.5 0.2 : 1 3.5 (8.9) n 5-2 2.5 1.0 6.4 : 1 2.75 (7.0) W5 so SO Comparative 3.75 0.25 0.07 : 1 6+ (15+) C5-2 OS 5-3 3.75 0.5 0.13 : 1 3.75 (9.5) SO so Surface Treatment m Example Billowing Comments Maximum Height (inches (cm)) After 10 Minutes CO c Alkenyl Bentonite Filler Weight Ratio of σ CO Ketene Dimer (VOLCLAY" HPM 75) Filler : Surface Addition Rate Addition Rate Size (kg / metric tonne) (kg / metric tonne) CO 5-4 3.75 1.0 0.27 : 1 3.0 (7.6) x m Comparative 5.0 0.25 0.05 : 1 6+ (15+) 21 C5-3 c Comparative 5.0 0.5 0.1 : 1 6+ (15+) m C5-4 5-5 5.0 1.0 0.2 : 1 3.5 (8.9) 5-6 5.0 1.5 0.3 : 1 2.75 (7.0) alkenyl ketene dimer @ 0.47 kg / metric tonne paper o H SO SO Os 42 The preceding specific embodiments are illustrative of the practice of this invention. The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference is made to the appended claims, rather than the foregoing specification, as indicating the scope of the invention.

Claims: 43 CLAIMS What Is Claimed Is: 1. A method of improving high speed precision paper converting or reprographic operations comprising surface sizing paper used in high speed precision converting or reprographic operations with a reactive sizing agent and an inorganic filler, the inorganic filler being applied in an amount effective to improve paper runnability with the weight ratio of the inorganic filler to the surface sizing agent being about 0.1 : 1 to about 10: 1. 2. The method of claim 1 wherein the reactive sizing agent is a 2-oxetanone sizing agent. 3. The method of claim 2 wherein the 2 -oxetanone sizing agent is a ketene dimer. 4. The method of claim 2 wherein the 2-oxetanone sizing agent is a ketene multimer. 5. The method of claim 2 wherein the 2-oxetanone sizing agent is selected from the group consisting of an alkyl ketene dimer, an alkyl ketene multimer, an alkenyl ketene dimer and an alkenyl ketene multimer, 6. The method of claims 2-5 wherein the 2 -oxetanone sizing agent is a liquid at 35°C. 7. The method of claim 6 wherein the 2-oxetanone sizing agent is a liquid at 20° C. 8. The method of any of the preceding claims wherein the inorganic filler is selected from the group consisting of kaolin, titanium dioxide, silicon dioxide, bentonite and calcium silicate. SUBSTTΓUTE SHEET (RULE 26) 44 9. The method of claim 8 wherein the inorganic filer is kaolin. 10. The method of claim 8 wherein the inorganic filer is titanium dioxide. 11. The method of claim 8 wherein the inorganic filer is silicon dioxide. 12. The method of claim 8 wherein the inorganic filer is bentonite. 13. The method of claim 8 wherein the inorganic filer is calcium silicate. 14. The method of any of the preceding claims wherein the inorganic filler has a mean particle size of less than about 10 μm. 15. The method of claim 14 wherein the inorganic filler has a mean particle size of less than about 5 μm. 16. The method of claim 14 wherein the inorganic filler has a mean particle size of less than about 2 μm. 17. The method of any of the preceding claims wherein the weight ratio of inorganic filler to surface size is about 0.2:1 to about 5: 1. 18. The method of any of the preceding claims wherein the paper is surface treated with reactive size at an addition rate of about 0.02 to about 5 kg per metric tonne of paper. 19. The method of any of the preceding claims wherein the inorganic filler is used in combination with a water-soluble inorganic salt. 20. The method of claim 18 wherein the water-soluble inorganic salt is selected for the group consisting of a calcium halide, a magnesium halide and a sodium halide. 45 21. The method of any of the preceding claims wherein the paper has a basis weight of about 30 to about 200 g/m 2 . 22. The method of claim 21 wherein the paper has a basis weight of about 40 to about 100 g/m 2 . 23. The method of any of the preceding claims wherein the paper is an alkaline fine paper. 24. The method of claim 23 wherein the paper is selected from the group consisting of forms bond, cut size paper, copy paper, envelope paper and adding machine tape. 25. The method of any of the preceding claims wherein the process comprises converting the paper into forms bond, cut sized paper, envelopes or adding machine tape. 26. A method of improving high speed precision paper converting or reprographic operations comprising surface sizing paper used in high speed precision converting or reprographic operations with a reactive sizing agent that is a 2-oxetanone that is a liquid at 35 °C and an inorganic filler selected from the group consisting of kaolin, titanium dioxide, silicon dioxide, bentonite and calcium silicate, the inorganic filler being applied in an amount effective to improve paper runnability with the weight ratio of the inorganic filler to the surface sizing agent being about 0.1 : 1 to about 10: 1. 27. A method of preparing fine paper comprising: (a) surface sizing the paper with 2-oxetanone sizing agent, and (b) apply inorganic filler, wherein the ratio of the inorganic to the surface sizing agent is about 0.1 : 1 to about 10: 1. 28. The method of any of the preceding claims wherein the surface sizing is carried out with a 2-oxetanone that is a liquid at 35 °C and at least one other sizing agent. 46 29. The method of claim 28 wherein the other sizing agent is an alkyl ketene dimer having straight chain alkyl groups or alkenyl succinic anhydride 30. A sizing composition useful as a surface size for alkaline fine paper comprising a 2-oxetanone reactive sizing agent that is a liquid at 35 °C and an inorganic filler, the weight ratio of the inorganic filler to the reactive sizing agent being about 0.1 :1 to about 10:1. 31. The composition of claim 30 wherein the inorganic filler is selected from the group consisting of kaolin, titanium dioxide, silicon dioxide, bentonite and calcium silicate. 32. The composition of claims 30 or 31 wherein the weight ratio of inorganic filler to reactive sizing agent is about 0.2:1 to about 5:1. 33. Fine paper is described in any of claims 1-29 or surface sized with the sizing agent of any of claims 30-32.

Inventors: BRUNGARDT CLEMENT L, GAST JOHN C, BRUNGARDT, CLEMENT, L., GAST, JOHN, C.
Applicants: HERCULES INC, HERCULES INCORPORATED
Application year: 1999
Main classification: D21H21
IPC codes: D21H17, D21H21