JP2014523978A - Composition for use at the wet end when making paper - Google Patents

Abstract

  A composition for use as an enhancer in the wet end of papermaking, comprising a surface-modified non-woody plant fiber and a starch component.

Description

  The present invention relates to a novel composition for use at the wet end during papermaking. In particular, it relates to compositions comprising both starch and non-woody plant fibers and their use in enhancing the dry strength of paper products.

  In papermaking, cellulose is mixed with water and pulped to form a slurry (or “cellulose pulp”). The slurry is then screened to collect the cellulose fibers and produce a paper web. Excess liquid is drained. This process is called the “wet end” of papermaking. Next, after the press part is passed through the web to further reduce the water content, a drying process is typically performed using a steam heated or oil heated drying cylinder. The dried paper web can then be impregnated with a sizing composition or coated and then cut to size.

  The strength of the final paper product depends on a number of factors such as, for example, the use and nature of the sizing or coating composition, the use and nature of the wet end additive, and, of course, the nature of the pulp itself. Determined. Typically, paper made from woody virgin pulp is stronger than paper made from pulp obtained from recycled paper. In fact, the strength of the paper product decreases with each repulping cycle. At the same time, there is pressure in the paper industry that calls for expanding the use of recycled paper, for both environmental and cost reasons. Thus, it is clear that there is a need to increase-or at least maintain the dry strength of paper products containing recycled materials.

  One possible solution is the use of a dry paper strength enhancer at the wet end of the papermaking process. The dry paper strength enhancer used in the wet end is typically composed of cationic starch. Cationic starch usually interacts with anionic cellulose fibers in the pulp to reinforce the paper web by forming a composite matrix. Unfortunately, such cationic starches have been found to be less effective when used in combination with recycled materials. In fact, the recycled material contains a high concentration of anionic trash, which preferentially “saturates” the cationic starch and limits the interaction between the cationic starch and the anionic cellulose fibers. It is thought that it will be done. In papermaking in a closed process, these trashes will be deposited with salts that provide an electrostatic interaction between the anionic fiber and the cationic starch. As a result, the use of cationic starch in combination with recycled materials results in poor performance for efficiently enhancing dry strength.

  To date, a number of synthetic starch based enhancers have been proposed as alternatives. For example, such agents include polyacrylamide and polyvinylamine, which are more efficient even when used in combination with recycled materials. Unfortunately, these agents are also very expensive and are considered undesirable from an environmental point of view.

  Thus, the art maintains the dry strength of a paper product by using it at the wet end of papermaking, even when it contains recycled pulp material and even when the process is closed. It is clear that there is a need to develop naturally-occurring additives that can be further enhanced. The present invention provides such an additive.

  According to a first aspect of the present invention, there is provided a composition for use as an enhancer in a papermaking wet end, the composition comprising a surface modified non-woody plant fiber and a starch component, The fiber and starch components are preferably linked.

  According to a further aspect of the present invention, there is provided a method for producing the above composition, as well as a method for producing a paper product using such a composition. A paper product obtained by such a process is provided in another aspect of the present invention.

  According to a further aspect of the invention, a surface-modified non-coated material is used to enhance the dry strength of paper, preferably paper containing recycled material and / or paper produced with a conductivity greater than 4 mS / cm. Use of woody plant fibers is provided.

  The present invention provides a composition for use as an enhancer in the wet end of papermaking, the composition comprising a surface modified non-woody plant fiber and a starch component.

Plant Fiber As used herein, the term “non-woody plant fiber” refers to any fiber material that is not derived from wood, where “wood” is a definition described in a general dictionary. (Ie, it is a hard, fibrous material composed mostly of tree trunks and branches). Examples of suitable non-woody plant fibers (herein simply “plant fibers”) will be apparent to those skilled in the art. Examples of suitable non-woody plant fibers include, but are not limited to, cereal fibers, seed fibers, bean fibers, fruit fibers, algae fibers, and mixtures of two or more thereof.

  The plant fiber can be provided in such a form, ie in the form of a fiber material. Examples of suitable fiber materials include, for example, grain bran (eg wheat bran), vegetable pods (soybean pods and / or pea pods), bagasse, corn stover, straw, switchgrass, citrus Examples include fibers (such as citrus pulp fibers), seaweed residues, and mixtures of two or more of these. The fiber material preferably consists of at least 50% by weight, more preferably at least 75% by weight, based on dry weight. Certain fiber materials may include non-fibrous elements such as protein or starch. As an example, soybean pods typically contain about 10% protein by weight and about 20% starch by weight in addition to the fiber component. Thus, according to at least one embodiment, the fibrous material will comprise about 50-85% by weight fiber based on dry weight.

  The plant fibers are preferably anionic (ie preferably have a negative net charge). According to certain embodiments, it has a continuous zeta potential (SZP) of 0 to -30 mV, preferably -1 to -20 mV, more preferably -1 to -15 mV. According to another embodiment, it preferably has an anionicity of 10-2000 μg / g, more preferably 100-1000 μeq / g (shown per gram of dry material under pH 7).

  The plant fibers are advantageously surface modified to increase their ability to interact (mechanically or electrostatically) with the cellulose fibers in the cellulose pulp. By way of example only, the fibers may be modified overall or in specific surface areas.

  As will be appreciated by those skilled in the art, the term “surface modified” or “surface modified” is not limited to modifications that only affect the surface of the fiber. In fact, modification can be brought about by changing other properties of the fiber (eg internal structure). For example, surface modification can be obtained by grinding, heat treatment (eg, cooking and / or extrusion), chemical modification, or any combination thereof. Thus, according to certain embodiments, the plant fibers may be provided in the form of powder or flakes.

  The composition of the present invention also includes a starch component.

Starch Component Without being bound by theory, it is believed that the starch component enhances the ability of plant fibers to interact with cellulose pulp and acts almost as an adhesive between plant fibers and cellulose fibers.

  As used herein, the term “starch component” refers to one or more natural starches, one or more modified starches, one or more starch derivatives (such as dextrins), or mixtures thereof. The starch component may be derived from any type of starch or any starch source. For example, the starch component may include waxy and / or non-wax-like starch and is derived from wheat, corn, potato, tapioca, peas or any other available starch resource, and mixtures thereof It may be.

  The starch component may be subjected to one or more modifications such as chemical, enzymatic and / or thermal modifications. Thus, the starch component can include, for example, one or more cross-linked, etherified, esterified, hydroxypropylated, and / or thinned starches. Preferably, the starch component may be anionic or cationic, i.e. have a negative net charge or a positive net charge. More preferably, the starch component is cationic. According to certain embodiments, the starch component consists of one or more cationic starches.

  According to one promising embodiment, some or all starch components may be provided as part of the fiber material. As noted above, plant fibers may be provided in the form of fiber materials that may contain certain non-fibrous elements such as starch. By-product fibers recovered from wheat processing may contain, for example, up to 50% starch by weight. When using fibers from such by-products as plant fiber resources, it is not necessary to add any additional starch to the composition (or add only a small amount of starch).

  The starch component is preferably “activated”, ie, can form a dispersion in cold water (ie, about 20-25 ° C.). Preferably the starch component is solubilized, i.e. forms (or can form) a stable colloidal dispersion. Such conditions can be, for example, cooking (heating, steaming, etc.), hydrolysis (eg, with acid), extrusion, alpha, roll drying, or any of these treatments It can obtain by the combination of these. According to one promising embodiment, the one or more starch components may comprise one or more cold water soluble cationic starches.

  In use, the composition of the present invention is preferably 1-90 wt%, preferably 1-50 wt%, more preferably 5-30 wt%, such as 20-25, based on the total dry weight of the composition. It may contain a weight percent starch component. Ideally, the composition comprises plant fiber and starch components in a 1:20 to 20: 1 ratio, preferably 1: 1 to 10: 1 ratio, based on dry weight.

  Preferably, the starch component and the non-woody plant fiber are linked. As used herein, the term “linkage” refers to at least a portion of the surface of some or all plant fibers, either through absorption, electrostatic interaction, chemical bonding or any other means. It may refer to a direct or indirect linkage that retains the starch component. In preferred embodiments, at least some of the cationic starch component can be linked to the anionic plant fiber by direct electrostatic bonding. Alternatively, anionic starch can be linked to anionic plant fibers by cationic crosslinking (eg, cationic trivalent or divalent metal ions such as calcium or aluminum, or cationic starch).

  Advantageously, the composition according to the invention may comprise up to 100% by weight of plant fibers and starch components, based on the total dry weight. Preferably, 80 to 100 wt%, more preferably 90 to 100 wt% of vegetable fiber and starch components may be included, based on the total dry weight.

Other Optional Components The composition of the present invention may further contain one or more optional components. These are preferably selected from wet end additives well known to those skilled in the art. Examples of such wet end additives include curing agents, fluidity improvers, lubricants, antifoaming agents, release agents, fluorescent whitening agents, preservatives, yellowing inhibitors, ultraviolet absorbers, and antioxidant substances. , Solubilizers, antistatic agents, pH adjusters, water resistance agents, wet strength enhancers, sizing agents, dehydration aids, greases and oil resistance agents, and combinations of two or more thereof.

  When included, the amount of each of these additives is determined by standard techniques and taking into account the properties desired for the final paper product. Advantageously, the composition of the present invention need not contain any synthetic dry paper strength enhancer, and therefore preferably does not contain at all. In practice, the compositions of the present invention preferably contain less than 5% by weight of any synthetic additive, preferably less than 2% by weight, more preferably less than 1% by weight, based on the total dry weight. As used herein, “synthetic additives” are understood to refer to non-naturally occurring chemical additives such as polyacrylamide, polyvinylamine, melamine resins, and urea formaldehyde resins.

  The composition of the present invention is preferably provided in powder form. Alternatively, it may be provided in slurry form or in the form of an aqueous composition. In such cases, it may comprise 10% to 98%, preferably 50% to 98%, more preferably 70% to 95% by weight of total dry ingredients, based on the total weight of the composition.

Enhancer The composition of the present invention is intended for use as an enhancer. In particular, when used in the manufacture of paper products, the enhancer of the present invention can maintain or enhance the dry strength of the product (e.g., measured by common CMT, SCT and / or Burst tests). ) It is also believed that the compositions of the present invention provide good or improved wet strength, i.e., provide good or improved strength to the wet paper web in the papermaking process, as described in more detail below. .

  Advantageously, the composition of the present invention may also be used to enhance the wet and / or dry strength of paper products containing recycled materials compared to the use of only cationic starch. it can. The composition of the present invention is considered to exhibit at least the same performance as a synthetic agent such as polyacrylamide and / or polyvinylamine. The compositions of the present invention can also be used to enhance the wet and / or dry strength of paper products with electrical conductivity greater than 4 mS / cm.

  Further advantages of the composition of the present invention include important factors related to the papermaking process, such as retention (retention of cellulose fibers on the web) or dewaterability (ease of water removal from paper pulp). It does not harm the characteristics. In some instances, it is even believed that the compositions of the present invention may improve these properties (ie, increase water retention and increase dewaterability).

The manufacturing method of a composition This invention further provides the manufacturing method of the said composition. In particular, the present invention provides a method for producing a composition for use as an enhancer in the wet end of papermaking,
(A) a step of preparing a composition comprising a plant fiber and a starch component; and (b) a step of surface-modifying at least the plant fiber.
Or:
(A) preparing a composition containing plant fibers;
(B) a step of surface-modifying the vegetable fiber, and (c) a step of mixing the modified plant fiber composition with the starch component.

Where it is desired or intended that the starch component be cationic or anionic, cationization or anionization of the starch component can be performed before or during contact with the plant fiber. Thus, for example, if the starch component is desired to be cationic, the method of the present invention may include the following steps:
(A) preparing a composition comprising plant fibers and starch components;
(B) a step of surface-modifying at least the plant fiber; and (c) a step of cationizing the starch component (where b and c may be carried out in any order);
Or:
(A) preparing a composition comprising plant fibers and a cationic starch component, and (b) at least modifying the surface of the plant fibers,
Or:
(A) preparing a composition containing plant fibers;
(B) a step of surface modifying the plant fiber, and (c) a step of mixing the modified plant fiber composition with the cationic starch component,
Or:
(A) providing a composition comprising a surface-modified vegetable fiber and a starch component; and (b) cationizing the starch component.

Activation of plant fibers (by surface modification) and / or starch components, whether carried out together or separately, is just one example: heat treatment (eg cooking, jet cooking, drying or semi-finishing) Dry heat treatment, extrusion, roll drying ...), mechanical treatment (eg dry grinding or wet grinding), chemical treatment (eg oxidation), and / or pregelatinization at least for the starch component. Preferably, both plant fiber and / or starch components are cooked. Also, the plant fiber is preferably pulverized. When pulverized, the plant fiber is preferably pulverized in an average particle size (D ₅₀ ) of 30 to ₅₀₀ μm, preferably 30 to 200 μm, more preferably 30 to 100 μm. According to certain embodiments, the cooking may consist of jet cooking at a temperature in the range of, for example, 80-180 ° C, or 100-140 ° C.

  The method of the present invention preferably further comprises the step of forming (or connecting to) the formation between the plant fiber and the starch component. As described above, this connection may be direct or indirect. Preferably, the plant fiber and starch component are linked by electrostatic interaction. Thus, according to a promising embodiment, the method of the present invention comprises contacting the plant fiber and starch component in water. This step is advantageously carried out at the wet end of the papermaking before use of the composition, i.e. in clean water, in order to prevent the interaction of the starch component with the non-fibrous material. Thus, “clean water” is to be construed as having a general meaning, ie it does not refer to waste water or water containing high levels of trash (ie, cloudy water). “Clean water” need not mean either sterile water or deionized water (although it should be understood that such “ultra-clean” water can also be used). Rather, it typically refers to fresh water or simply “tap water”.

Thus, according to a particular embodiment of the present invention, there is provided a method for producing a composition for use as an enhancer in the wet end of papermaking, the method comprising:
(A) providing a surface-modified plant fiber and a cationic, preferably cold water soluble starch component; and (b) mixing the plant fiber and starch component in clean water to produce the plant fiber and starch component. Connecting, preferably by electrostatic interaction.

According to a preferred embodiment, the starch component and plant fiber are brought into contact in clean water and then cooked to form a connection between the two components (ie, to allow them to interact). Thus, for example, according to a preferred embodiment, the present invention provides a method for producing a composition for use as an enhancer in the wet end of papermaking, the method comprising:
(A) preparing a plant fiber and a cationic starch component;
(B) The process of mixing a vegetable fiber and a starch component with clean water, and (c) The process of heating the aqueous solution mixed at the process (b) to 80-180 degreeC preferably is included.

  Preferably, the plant fiber and starch component are contacted at a high concentration. “At high concentrations” means that the plant fiber and starch components are preferably mixed at 1-30% dry solids, more preferably 5-20% dry solids, and of course, specific implementations. In form, the dry solids concentration may be even higher. Without being bound by theory, it is believed that such a concentration promotes the interaction between the plant fiber and the starch component. Of course, if desired, the composition may be diluted prior to use and / or further optional ingredients may be added to the composition.

Products and Manufacturing Methods The compositions that can be obtained by this method are all part of the present invention, together with their use as enhancers and their use as paper products made therewith. In particular, the present invention provides a method for producing a paper product comprising the following steps (a) and (c):
(A) a step of contacting the composition as described above (ie, produced by any of the above methods) with cellulose pulp; and (c) a step of producing a paper product from the pulp obtained in step (a). .

  The term “cellulose pulp” refers to an aqueous suspension of cellulosic fibers as typically used in the paper industry in the manufacture of paper products. Such pulp includes, for example, any type of pulp suitable for use in the manufacture of paper products such as paper sheets, paperboard (cardboard or cardboard), and packaging or case materials. As interpreted. Pulp can also include wood virgin pulp, pulp derived from recycled materials, mechanical pulp, and the like. The pulp may be bleached or unbleached and may or may not contain recycled material.

  Preferably, the pulp comprises recycled material (ie, regenerated cellulose fiber). Recycled material includes any type of waste paper or waste paper ("waste") that is recovered and repulped for use. Examples of suitable wastes include, for example, crushed unused waste and / or used waste. Recycled materials may or may not be deinked, bleached or any other treatment prior to use, and these materials include materials that have already been recycled one or more times. According to a promising embodiment, the pulp can be composed entirely of recycled material. Preferably, the recycled material may comprise at least 50 wt%, more preferably at least 75 wt%.

  Without wishing to be bound by theory, the compositions of the present invention are believed to be particularly useful in the manufacture of paper products containing recycled materials. In particular, the compositions of the present invention have better wet and dry strength (and at least equivalent to their synthetic substitutes) when making paper products containing recycled materials compared to when used with cationic starch alone. Is considered to provide properties without adversely affecting drainage, water retention or other important parameters.

  According to a particular embodiment, the composition according to the invention is such that the composition according to the invention is 0.2 to 20% by weight, preferably 0.5 to 10% by weight, more preferably 2 to 2, based on the dry weight of the pulp. Used to contact 6 wt% cellulose pulp. Expressed differently, the paper product of the present invention preferably comprises surface modified vegetable and cellulose fibers from 1: 500 to 1: 4, more preferably from 1: 100 to 1:20, more preferably. In a weight ratio of 1:60 to 1:30.

  The invention will now be described in greater detail by the following non-limiting examples.

  Multiple tests were performed using 100% recycled OCC paper with a conductivity of 4.7 mS / cm. In each case, the starch and fiber material were cooked together and then mixed with the pulp. Next, a pilot paper machine manufactured by Kemira (model: long net paper machine; paper width: 30 cm; head box concentration: 0.25 to 0.5%, circular distributor; vacuum foil on the wire part) foils); double press, double felt press section; oil heated drying cylinder; machine speed: 2.5 m / min).

  Further tests were carried out using 100% recycled OCC paper with a conductivity of 11 mS / cm (ie contaminated). In each case, the starch and fiber material were cooked together and then mixed with the pulp.

In all cases “starch” uses “type C ^* Bond 05946” with a degree of substitution of 0.042 available from Cargill, “wheat fiber” is up to ground wheat bran with an average particle size of 43 μm, The “soybean fiber” was a crushed soybean pod having an average particle size of 75 μm.

Method CMT is measured according to the standard test method: DIN EN ISO 7263.
SCT is measured according to standard test method: DIN 54518.
The burst strength is measured according to standard test method: Mullen DIN 53141 Part 1 (Tapi 403-OM-85).
The tear strength (breaking load and breaking length) is measured according to the standard test method: DIN EN ISO 1924-2.

Claims (15)

  A composition for use as an enhancer in the wet end of papermaking, comprising a surface modified non-woody plant fiber and a starch component.   The composition according to claim 1, wherein at least a part of the starch component is linked to the plant fiber.   The composition according to claim 1 or 2, characterized in that the surface-modified plant fiber is anionic and preferably has an anionic degree of 10 to 2000 µeq / g.   The surface-modified plant fiber is selected from the group consisting of cereal fiber, seed fiber, bean fiber, fruit fiber, algae fiber, and a mixture of two or more thereof. The composition as described in any one of -3.   The surface of the plant fiber is modified by a method selected from the group consisting of grinding, heat treatment, chemical modification, coating, and any combination thereof. The composition as described in any one of these.   The composition according to claim 1, wherein the surface-modified plant fiber has an average particle size of 30 to 500 μm.   7. Composition according to any one of the preceding claims, characterized in that the starch component is selected from cationic or anionic starch components.   The composition according to any one of claims 1 to 7, wherein the starch component is soluble in cold water.   The method to manufacture the composition as described in any one of Claims 1-8. The method according to claim 9, comprising: (a) preparing a composition comprising a plant fiber and a starch component; and (b) at least modifying the surface of the plant fiber. (A) preparing a composition containing plant fibers;
10. The method of claim 9, comprising: (b) surface modifying the plant fiber; and (c) mixing the modified plant fiber composition with a starch component. (A) Cellulose pulp, preferably cellulose containing regenerated cellulose fibers, the composition according to any one of claims 1 to 8, or the composition obtainable by any one of claims 9 to 11. Contacting with pulp,
(B) A method for producing a paper product, comprising a step of producing a paper product from the pulp obtained in step (a).   A paper product obtainable by the method according to claim 12.   The paper product according to claim 13, comprising surface modified non-woody plant fibers and cellulose fibers in a weight ratio of 1: 500 to 1: 4.   Surface-modified non-woody plant fibers and starch components to enhance the dry strength of paper, preferably paper containing regenerated cellulose fibers, and / or paper made to have a conductivity greater than 4 mS / cm Use of a composition comprising