MXPA99010599A - Soft absorbent paper product containing deactivated ketene dimer agents - Google Patents

Abstract

New and improved methods and products are disclosed relating to increasing the softness of paper sheets, without effecting their wetability. Increased softness, without loss of wetability is obtained by adding deactivated ketene dimer sizing agents to the sheet

Description

DB PRODUCT HIGHLY ABSORBENT AND SOFT PAPER CONTAINING AGENTS DB DIMERO CETENA BACKGROUND DB THE INVENTION The use of dimer-based ketene agents in the paper industry to impart sizing or water resistance to well-known paper products. Such agents are commercially available from Hercules, Inc., of Wilmington, Delaware under the trade names such as AQUAPEL® and HERCON®. Some patents describe the compositions, variations and uses of these types of agents and are: Inventor Patent No. Issued Aldirch and others 3,922,243 November 25, 1975 Anderson 3,957,574 May 18, 1976 Aldrich and others 3,990,939 November 9, 1976 Aldrich 4,017,431 April 12, 1977 Aldrich and others 4,087,395 May 2, 1978 Duce 4,240,935 December 23, 1980 Duces 4,243,481 6 January 1981 Dumas 4,279,794 21 July 1981 Dumas 4,295,931 October 20, 1981 Ban ert and others 4,407,994 October 4, 1983 Bankert and others 4,478,682 October 23, 1984 Edwards and others 4,861,376 August 29, 1989 Cenisio and others 4,919,724 April 24, 1990 Walkden 4,927,496 May 22, 1990 Nolan and others 5,484,952 January 16, 1996 Zhang 5,525,738 June 11, 1996 The descriptions of which are incorporated herein by reference.

These sizing agents when added to the wet end of the paper machine, in the sizing press, or to the finished product in an application outside the machine imparts water resistance to the paper, by decreasing the hydrophilicity of the sheet. The use of these sizing agents in the writing paper, in the lining cardboard, in the bags of stores and boxes of well-known milk since all these products require sizing. These types of sizing agents are well known because they produce a very hard material (with high wetting resistance) such as a milk box. The use of these dressing agents in tissue and towels, although not unknown, has been very limited because water resistance is not desirable in these products. On the contrary, it has generally been an objective in the tissue and paper towel industry to increase rather than decrease the rate, which the product is moistened and the total amount of water that the product can absorb. An example, however, of the use of dimer ketene sizing agents in tissue and towel products to increase water resistance is found in European Patent Application No. 0 144 658 in the name of Dan Eneres, assigned to Kimberly-Clark Corporation.

It has been found that the use of dimer ketene prepping agents in tissue and towel increases the softness of these products in the sense that wetting agents or surfactants can be used in conjunction with these prepping agents to eliminate sizing without eliminating The benefit of softness. Therefore, the softness can be increased even when the hydrophilicity or water absorption of the products is not materially affected.

SYNTHESIS OF THE INVENTION In one embodiment of the present invention, an absorbent and very soft tissue product comprises long and short papermaking fibers and a dimer ketene sizing agent is provided. A soft absorbent paper product comprising papermaking fibers and at least about one pound per tonne of dimer ketene-sizing agent, tissue is also provided having an absorbency rate test of less than about 40 seconds. .

In a further embodiment of this invention, an absorbent and soft tissue sheet comprises: a first layer and a second layer with the first layer comprising predominantly long papermaking fibers and the second layer comprising predominantly short papermaking fibers and at least one of the layers further comprises a dimer ketene-sizing agent and a surfactant and the layer comprising the dimer ketene is easily humectable with water. The tissue sheet can be creped or dried continuously. This soft tissue sheet can have a test of absorbency rate of less than about 10 seconds.

In yet another embodiment of the present invention, an absorbent paper sheet having improved softness comprises a first sheet surface and a second sheet surface and a layer comprising papermaking fibers. The layer that has a surface which corresponds to a surface of the paper sheet. The surface of the layer has a ketene dimer primer and the surface of the sheet has a surfactant there. The wettability of the sheet is equivalent to a sheet of the similar composition but not having the dyeing agent ketene or the wetting agent therein. This sheet of paper can be a toilet sheet that can have a second layer comprising fibers for making paper. This sheet of paper can be a towel product that can have a second layer comprising fibers for making paper. This sheet of paper can be a facial tissue having a second layer comprising fibers for making paper. In a further embodiment, the sheet has a third layer.

In yet another embodiment, there is provided an absorbent paper sheet having improved softness comprising fibers for making cellulose paper and a dimer ketene primer agent and a wetting agent. The leaf pretender is not more than about three times the dresser of a leaf of a similar composition but not having the dimer ketene finishing agent and the wetting agent.

In an alternate embodiment of the invention, there is provided a method for making an absorbent and soft paper sheet product having an improved smoothness comprising forming an aqueous solution comprising fibers for making paper in a pulp reducer; combine a dyeing ketene finishing agent with fiber to make paper; combining a surfactant with the fibers for making paper; and removing the water from the aqueous solution to form a sheet of paper. Dimer ketene primer can be combined with the fibers to make paper before, during or after the removal of water from the solution.

In yet another alternate embodiment of the invention, a very soft absorbent paper product is provided which comprises a mixed base sheet having a ketene dimer primer. This mixed base sheet can have a mixture of long and short paper fibers.

DRAWINGS Figure 1 is a schematic process flow diagram that generally shows the manufacture of paper products.

DETAILED DESCRIPTION OF THE CURRENTLY PREFERRED INCORPORATIONS OF THE INVENTION The ketene dimers used in the industry to impart sizing, or water resistance to paper, have a general chemical structure of: R! -CH = C-CH-R2 0-C = 0 in which R, and I ^ can be a wide range of carbon column sturctures. The structures and known methods for making these paper products are described in the above-mentioned patents which are incorporated herein by reference.

When such a prescribing agent is used to impart water resistivity to paper, it is speculated that the four-membered ring consisting of one oxygen and three carbon atoms, also known as the lactone ring, is primarily responsible for the formation of a covalent bond. to cellulose fiber. It is speculated that the lactone ring undergoes a reaction with the hydroxyl group on cellulose. Once this reaction is completed, the R groups are then re-oriented through the application of heat, the type of air or pressure out of the cellulose fiber. Therefore, these in effect create a hydrophobic monomolecular layer on the outer surface of the cellulose fiber. It is speculated that this outer hydrophobic surface layer provides water resistivity to the paper product that is observed when these prepping agents are used.

To counteract this priming effect, surfactants such as wetting agents or surfactants can be added to the sheet, either at the wet end, the embryonic tissue, the dried sheet or outside the machine. Such surfactants are well known in the art and will include but are not limited to alkoxylated alcohols (EO, PO, or BO), phenols, polyols, fatty amines, phosphate esters, sorbitan ester, hydroxylated alkyl polysaccharide or alkoxylated, the phosolipids, the heterocyclic compounds and the saturated or unsaturated fatty esters. This list will also include anionic, cationic, nonionic and amphoteric surfactants, such agents can also be found in or function as defoamers or lubricants. The softness benefits of dimero keten appendage agents are obtained without any loss of material hydrophobia.

Referring to Figure 1, which is a schematic process flow diagram of a papermaking process, the cellulose fibers are prepared in a pulp reducer (not shown) to form an aqueous solution of water fibers, which it is mentioned as a supply or a supply solution. The supply is pumped into a chest l, which can be mentioned as a discharge chest. From the discharge chest to the supply is pumped to another holding box 12, which can be mentioned as the chest of the machine. From the machine chest to the supply is pumped by the fan pump 3 to the head box 4 of the paper making machine 5. On or before the fan pump, the supply is diluted with water. Usually and preferably the dilution is made with return water; mentioned as white water, from the paper making machine. The flow of white water is shown by lines 6 and 7. Before dilution the supply is referred to as a thick supply and after dilution the supply is referred to as a water supply.

The water supply is then dewatered by the forming section 8 of the paper machine to form an embryonic tissue of wet cellulose fibers. The wet fabric is then transferred to a dryer 9, which removes the water from the wet tissue forming a sheet of paper. The sheet of paper then leaves the dryer and rolls onto a reel 10.

It will be understood that Figure 1 is a general description of the process for making paper and that it is intended to illustrate the process and that it is not desired to limit or narrow the scope of the present invention. Many variations of this process and equipment are well known to those skilled in the art of papermaking. For example, various types of dryers can be used including air dryers, Yankee dryers with and without creping, tunnel driers and can dryers or any combinations thereof. Although the scheme generally shows a twin wire type forming section, other forming sections known in the art can be used. Additional components can also be added or removed from the process. For example, screens, filters and refiners, which are not illustrated, can typically be placed between the pulp reducer and the headbox. The transfer section 11 of the paper making machine may be present or may be expanded to include additional water removal devices. Additional steps may also be added to the machine after the dryer and before the reel, such as calendering and the use of a size press, even when additional drying is usually required after a press application is used. right away. The calendering and coating operations can also be carried out outside the machine.

Paper sheets can be made of long paper fibers (soft wood) of short paper fibers (hardwood), secondary fibers, other natural fibers, synthetic fibers or any combination of these or other known fibers by those skilled in the art and papermaking to be useful in papermaking. The long papermaking fibers are generally understood to have a length of about 2 mm or greater. Particularly suitable hardwood fibers include eucalyptus and maple fibers. As used herein, the term "papermaking fibers" refers to any and all of the foregoing.

As used herein, and unless otherwise specified, the term "sheet" generally refers to any type of sheet of paper. For example, of tissue, face towel, tissue for the toilet, or any heavier, creped or non-creped, blended, multi-layer or single-layer or single-stratum or multi-stratum base product.

The dimer aggregator 70 can be added to the wet extruder to make paper to either the thick or watery supply as is known in the art. In addition to the wet end aggregate, the dimer haller dyeing agent may be added to the embryonic tissue, the partially dried leaf or the dried leaf. This can be sprayed or can be applied by roller application, either as an application on the machine or outside the machine. The optimal application point and method will depend on the particular paper type and the machine, however, these should be selected to optimize the distribution of the agent on or on the sheet, to minimize the effect on the run of the machine, as for reduce the amount of foam and maximize the amount of softness increase for the amount of the agent used. The wetting agent should preferably be applied downstream of the point of addition of the delivery agent. However, particularly in wet end applications, the wetting agent can be added at any point with respect to the point of addition of the sizing agent. It is optimal, however, to have the addition point of the sizing agent and the surface action agent as close as possible.

The dimer haller dyeing agent may be derived from either fatty acids from plants or animals, which may be saturated or unsaturated, branched or unbranched R groups. In addition, at least one R group can be substituted with H. The currently preferred R groups vary from Cj-C ^, it is further described that the chain lengths for these R groups vary from about C6 to about CJJ and even more desirably that the chain length varies from about C8-C18. Additionally, it is currently believed that it is easier to mask the one of the prescribing effect of chain lengths in the range of from about C8 to C12.

The amount of dimer ketene finishing agent that is added to the paper will depend on the dimer ketene that is being used of the type in paper composition that is being made, and in the manner and point in the papermaking process in which the agent It is added. Currently, between about 0.25 to about 5 pounds per tonne of paper (dry basis weight) of sizing agent can be used, although depending on the application the benefits of this invention can be seen with higher and lower amounts. They can be optimally used from about 0.5 to about 4 pounds for wet end vision. The practical upper limits for the amount of prime agent used will mainly be controlled by the run of the machine, the water absorption of the sheet and the cost. The amount of wetting agent or surfactant used will depend on the type of agent and the amount of the sizing agent used. Sufficient amounts of wetting agent to mask the primer should be used.

The addition of the wetting agent to the sheet materially prevents the wettability of the sheet, for example the sheet is not prepared. Therefore, the rate of absorption of water and the total amount of water that a sheet smoothed with dyeing agent arresting ketene and wetting agent can absorb is not materially different than an equivalent sheet that does not have those agents. These sheets may have as much as one to two times increase in sizing as compared to a sheet without the sizing agent, and they will still exhibit sufficient hydrophilicity.

The wettability of the sheet or the quantity of sizing can be measured in a number of ways. Of course all the samples used will be aged and tested according to the TAPPI standards.

Absorbency Rate Test - The absorbency rate is the time it takes for a product to saturate cavally in distilled water. Samples are prepared as 2-inch squares composed of 20 sheets of finished product using a matrix press (e.g. TMI DGD from Testing Machines Incorporated of Amityville, N.Y. 11701). The stratum of a finished product dictates the number of individual sheets. 1 stratum: 20 individual leaves 2 strata: 40 individual leaves 3 strata: 60 individual leaves When soft rolls are tested (single layer of tissue coming out of the tissue machine before layered into the furler), 40 individual soft roll sheets are used per sample.

Samples are stapled at all four corners using 4 Swingline speed point staples S.F. (staples are% inch wide with inch-long legs). The samples are tested in a constant temperature water bath at a depth of 4 inches (maintained through the test) keeping the distilled water at 30 +/- one degree Celsius. The sample is kept close to the surface of the water (two points of the grit in the downward position) and then pulled flat on the surface of the water. A timing is started (readable to O.ls) when the sample hits the water. When the sample is completely saturated, the stopwatch stops and the absorbing rate is recorded. A minimum of five samples were tested.

All tests were carried out in a standard laboratory atmosphere of 23 +/- 1 Celsius and 50 +/- 2% RH. All samples were stored in this laboratory at least four hours before the test. All samples were aged and tested at TAPPI conditions.

Hercules Stencil Test (HST) - A small volume of ink was placed on the paper sample to be tested. The amount of sample is typically from 1 to 5 layers of paper. A photoelectric eye then measures the time it takes for the reflectance of the sample to fall to a specific level from its original point. This test is typically used for bleached paperboard, cup supply, fine paper and linerboard grades. This test can be used to measure readiness in facial tissue classes.

Flotation Tests - A paper sample floated on an aqueous solution. The sample is timed and reaches its full when the sample has been completely saturated with the test solution. This type of solution use will depend on the final use of the paper. The typical solutions used are ink, water, fluorescent ink, and ammonium solutions. The use of flotation tests is usually limited to the types of thin paper. Linerboard, gypsum board and cup supply are typically not tested with this method due to the excessive time required to saturate the sample. A water bath saturation test can be used to measure sizing in the facial tissue classes.

Boiling Pot - This test measures the time required by the "boat" shaped paper sample to saturate completely in boiling water. This test is typically used for highly prepared classes such as plasterboard and plasterboard.

Valley Size Test - A paper sample is connected to each end of an electrode. The sample is immersed in a water solution and the conductivity of the paper sample, after a predetermined period of time was measured. The use of this test is typically limited to the types of "cylindrical" cardboard paper.

Carrier - Sizing is measured by the time necessary for a paper sample, soaked in an aqueous fluid, to complete an electrical circuit. This test has become very popular for use in lining carton classes.

Immersion Test - A sample of thickened paper and then soaked in a water bath for a predetermined period of time. The sizing was measured by the weight of the water that was absorbed during the test. This test is frequently used for fine paper classes.

Edgewick - A sample of paper is submerged on its edge, in a liquid sample of lactic acid, peroxide, coffee, etc. This test measures the amount of liquid that is taken by the paper over a defined period of time. This test is exclusively used for classes of paper packaging such as milk cartons and other liquid packaging applications.

Kleva - The end of the paper sample is immersed in a liquid bath. Sizing is measured by the amount of time it takes for the liquid to rise upward from the sample to a predetermined point. This test is very flexible and can be used for many classes booked.

Typically, tissue made without the use of capturing agents shows an absorbance rate test of from about 1 second to about 10 seconds or slightly less. The towel made without the capturing agents will typically show an absorbency rate of about 1 to about 50 seconds. When the tissue and paper towel are seized with a dye ketene arresting agent, it can be anticipated that the levels of sizing or water resistivity will increase substantially. For example, the absorbance rate tests for the tissue may increase as much as 25 seconds or more. The tissue having an improved softness of the use of dye kete arresting agents in conjunction with the surfactants remains hydrophilic having a very low resistance to very low wetting, for example, these are not tight and therefore easily moistened. The water absorbency rate test for smoothed sheets are from about 1 to about 4 seconds but can be up to about 4 seconds or more depending on the type of paper, the basis weight and other physical characteristics of the paper. the sheet. For tissue and paper towel products and water absorbency results of less than 40 seconds and is believed to show that the sheet is essentially hydrophilic and is seen as insignificant and low levels of sizing.

The prepping agents may exhibit a threshold effect on the development of water sensitivity. Thus, for example, at 2 initial pounds of prescribing agent per ton of paper may develop little or no increased water resistivity. At any higher amounts the increase in water resistivity can be substantial. This threshold level will vary, of course from sheet to sheet and from process to process. The use of the surfactants in conjunction with the prepping agents allows the addition of prescribing agent above the threshold amount to obtain the benefits of softness without experiencing a dramatic loss in hydrophilicity.

Below are examples of how dimer keten conditioning agents in conjunction with surfactants can be used to increase softness while having no applicable effect on hydrophilicity.

Handleaved studies are mixed with base sheets containing 50% hardwood and 50% softwood dosed with one pound per tonne of ketene dyeing agent and one pound per tonne of PEG 400 dioate (ethoxylated fatty alcohol) ). This will provide good smoothness and better water absorbency than one pound per ton of sizing agent only.

Handleaf studies are blended base sheets containing 70% hardwood and 30% softwood dosed at one pound per tonne of dye ketene trapping agent and one pound per ton of hydroxylated lecithin (phospholipid) to give a good smoothness and better absorbency rates than hand sheets with one pound per ton of a dimer ketene only agent.

Handleaved studies are mixed base sheets containing 70% hardwood and 30% softwood dosed with two pounds per tonne of ketene dyeing agent and one pound per ton of tricol 6974 (TOE (10) nonylphenol ) to give better absorbency rates than hand sheets with two pounds per tonne of dimer haller only.

Claims (22)

R E I V I N D I C A C I O N S

1. A highly absorbent and soft tissue product comprising long and short paper fibers and a ketene dimer primer.

2. A soft absorbent paper product comprising papermaking fibers and at least about one pound per tonne of a ketene dimer primer, the tissue has an absorbance rate test of less than about 10 seconds.

3. The paper product as claimed in clause 2, characterized in that the product comprises a three-layer base sheet.

4. The absorbent and soft tissue sheet comprising a first layer and a second layer; the first layer comprises predominantly long papermaking fibers and the second layer comprises predominantly short papermaking fibers; at least one of the layers further comprises a ketene dimer entrapping agent and a surfactant; and the layer comprising the wetting agent and dimer ketene being easily wettable by water.

5. The soft tissue sheet as claimed in clause 4, characterized in that the sheet is creped.

6. The soft tissue sheet as claimed in clause 4, characterized in that the sheet is dried continuously.

7. The soft tissue sheet as claimed in clause 4, characterized in that the absorbance rate test is less than about 10 seconds.

8. The tissue sheet as claimed in clause 4, characterized in that the tissue sheet comprises a third layer.

9. The sheet of absorbent paper having an improved softness comprising a first sheet surface and a second sheet surface; a layer comprising fibers for making paper; the layer has a surface; the surface of the layer corresponds to a surface of the paper sheet; the surface of the layer has a dyeing agent cetena there; the surface of the sheet has a surfactant there; and the wettability of the sheet is equivalent to a sheet of a similar composition but not having the dyeing agent ketene and the wetting agent therein.

10. The sheet of paper as claimed in clause 9, characterized in that the sheet is a tissue for toilet.

11. The sheet of paper as claimed in clause 10, characterized in that the bath tissue has a second layer comprising fibers for making paper.

12. The sheet of paper as claimed in clause 9, characterized in that the sheet is a towel product.

13. The sheet of paper as claimed in clause 12, characterized in that the towel product has a second layer comprising fibers for making paper.

14. The sheet of paper as claimed in clause 9, characterized in that the sheet is a facial tissue.

15. The sheet of paper as claimed in clause 14, characterized in that the facial tissue has a second layer comprising fibers for making paper.

16. The sheet of paper as claimed in clause 9, characterized in that it comprises a second layer and a third layer; the surface of the layer corresponding to the first sheet surface and the surface of the third layer corresponds to the second sheet surface.

17. An absorbent paper sheet having an improved softness comprising fibers for making cellulose paper and a dimer ketene diluent and a surfactant; the sheet captor being no greater than about 3 times the dresser of a sheet of a similar composition but not having the dimer ketene dressing agent and a surfactant.

18. A method for making a highly absorbent and soft paper sheet product having an improved softness comprising: (a) forming an aqueous solution comprising fibers for making paper in a pulp reducer; (b) combining a dye ketene primer agent with papermaking fibers; (c) combining a surfactant with the papermaking fibers; Y (d) remove the water from the aqueous solution.

19. The method as claimed in clause 18, characterized in that the dyeing agent ketene is combined with the fibers to make paper before the removal of water from the solution.

20. The method as claimed in clause 18, characterized in that the dye ketene capturing agent is combined with the papermaking fibers after removal of the water from the aqueous solution.

21. A highly absorbent and soft paper product comprising a mixed base sheet, a ketene dimer primer and a surfactant.

22. The highly absorbent and soft paper product as claimed in clause 21, characterized in that there is at least 1 lbs per ton of providing agent and the product has a water absorbency rate of less than 10 seconds. R E S MEN New and improved methods and products are described in relation to the increase of the softness of the sheets of paper, without affecting the wettability. The increased softness, without loss of wettability is obtained by adding dimer ketene preparing agents and a surfactant to mask the sizing of the sheet.