CN116157571A

CN116157571A - Filler composition containing microfibrillated cellulose and microporous inorganic particle composite material for paper and paperboard applications with improved mechanical properties

Info

Publication number: CN116157571A
Application number: CN202180054411.7A
Authority: CN
Inventors: D·斯库斯; J·菲普斯; T·里夫-拉尔森
Original assignee: Fibrin Technology Co ltd
Current assignee: Fibrin Technology Co ltd
Priority date: 2020-09-11
Filing date: 2021-09-03
Publication date: 2023-05-23
Also published as: KR20230066009A; MX2023002583A; BR112023004460A2; AU2021339980A1; WO2022053869A1; CA3189813A1; JP2023544488A; EP4185748A1

Abstract

Methods of making filler compositions comprising microfibrillated cellulose and one or more microporous inorganic particulate materials, and methods of making papermaking furnishes and paper products comprising microfibrillated cellulose and one or more microporous inorganic particulate materials.

Description

Filler composition containing microfibrillated cellulose and microporous inorganic particle composite material for paper and paperboard applications with improved mechanical properties

Technical Field

The present invention relates to a method for manufacturing paper comprising microfibrillated cellulose ("MFC") and a bulk microporous inorganic particulate material with improved mechanical properties by selecting a bulk microporous inorganic particulate material with optimal particle size and particle size distribution.

Background

Inorganic particulate materials are commonly used in graphic papers to enhance optical and printing characteristics. Because inorganic particulate materials (also referred to herein as "minerals" and "fillers") are much cheaper than pulp fibers, the use of inorganic particulate materials also results in cost savings for the papermaker. The amount of inorganic particulate material that can be used is limited because the inorganic particulate material has an effect on the strength characteristics of the paper, whether wet or after drying during manufacture.

The most important property limiting the content of inorganic particulate material during the manufacturing process is the tensile strength of the wet paper after pressing. On most paper machines, the paper is transported from the press section to the dryer section without support and is thus kept under tension, while still having a relatively high moisture content of up to 60%.

After drying, many paper grades require minimum tensile strength, burst strength and tear strength, as well as tensile strength in the "Z" direction (perpendicular to the plane of the paper) in order to resist damage during printing and paper processing. Other important sheet properties include bending resistance and sheet bulk or thickness.

The addition of microfibrillated cellulose (MFC) has been identified as a cost effective way to improve many important strength properties of paper, including wet strength during manufacturing, and thus enables the use of higher inorganic particulate material content and cost savings. However, both the addition of MFC and the increase in the inorganic particulate material content generally have the effect of densifying the paper, resulting in a decrease in sheet thickness.

Conventional filler compositions used in papermaking, such as heavy calcium carbonate (GCC) and kaolin clay, can slightly increase the paper thickness per unit mass of fibers because some of the inorganic particulate material particles occupy areas between overlapping fibers that would otherwise be tightly bound together and increase the spacing between fibers. However, most of the particles are located in void spaces in the fiber network that would otherwise be empty, and the net effect of replacing the fibers with fillers is to densify the paper, given that they have a higher density than the fibers.

MFC is firmly bonded to the fibers and pulls them together, which also reduces the paper bulk and thickness. Since the bending stiffness of paper sheets is very sensitive to their thickness, the use of MFC to increase the inorganic particulate material content may also have an adverse effect on this property. Thus, the increase in inorganic particulate material content achievable by adding MFC is generally limited by the bulk and stiffness of the paper, not its strength.

Microporous inorganic particulate material

Some types of fillers, such as calcined clays and scalenohedrons and aragonite Precipitated Calcium Carbonate (PCC), are composed of aggregates of particles having an open porous structure (i.e., these are examples of microporous inorganic particulate materials). Calcined clays are described in U.S. patent No. 3,586,523, which is hereby incorporated by reference in its entirety. Such calcined kaolin is a substantially anhydrous amorphous aluminum silicate that is obtained by calcining a particular type of kaolin (e.g., hard precipitated kaolin).

Precipitated Calcium Carbonate (PCC) in clustered form is known in the art, as disclosed in U.S. patent No. 5,695,733, which is hereby incorporated by reference in its entirety. The PCC is produced in a unique clustered form with a substantial proportion of particles having a prismatic morphology. Calcite, aragonite or vaterite is produced by controlling the solution environment used to produce PCC, i.e., the slaking, carbonation temperature of lime (calcium oxide), and the rate of carbon dioxide introduction. Also, depending on the processing conditions, calcite may have prismatic, scalenohedral or rhombohedral crystal forms.

Other examples of microporous inorganic particulate materials include chemically aggregated filler materials. Examples of such chemically aggregated fillers can be found in U.S. patent No. 4,072,537, which is hereby incorporated by reference in its entirety. Such microporous inorganic particulate materials comprise a composite silicate material comprising a clay component and a metal silicate component. The clay component is typically kaolin or kaolinite, and the metal silicate material is typically a water-soluble alkali metal silicate, such as sodium silicate.

As described in the' 537 patent, a preferred method for preparing a composite pigment includes the steps of: (a) forming an aqueous suspension of clay pigment, (b) mixing an amount of a salt, such as calcium chloride, into the clay slurry, (c) metering an amount of a silicate component, such as sodium silicate, into the slurry of clay and salt under high shear, and optionally, (d) adjusting the pH of the slurry to a pH of not less than pH4 by the addition of alum, prior to (e) filtering and washing the precipitated product to remove any soluble salts. The microporous composite silicate material is either directly used in the papermaking process or used after drying. Additional microporous inorganic particulate materials include materials such as diatomaceous earth and expanded perlite.

All of the foregoing microporous inorganic particulate materials are comprised of particles that contain rigid internal void spaces that persist during paper pressing and drying and should remain substantially intact after calendering.

Scalenohedral PCC, calcined clay and chemically aggregated fillers achieve this structure by forming open aggregates of smaller particles and firmly bonding the particles where they contact each other. Diatomaceous earth consists of particles that naturally contain pores. The ground expanded perlite consists of micron-sized glass bubble fragments. Thus, microporous inorganic particulate materials comprise discrete particles or aggregates of particles having an external dimension of a few microns, which contain void spaces within the volume defined by the external dimension that are several times smaller than the external dimension. In general, for the purposes of the present invention, the foregoing inorganic particulate materials are referred to herein as "microporous inorganic particulate materials".

When used in paper, these microporous inorganic particulate materials (added particulate material per unit mass) have a much greater impact on fiber spacing than the solid filler particles. This makes them more detrimental to the paper strength but produces increased light scattering, which is beneficial for the optical properties.

Another effect of inorganic particulate materials is to always increase sheet porosity (air permeability), which is a significant disadvantage in printing and paper processing. The effective density of microporous inorganic particulate materials is also lower than that of solid fillers, and when fibers replace fillers, the combination of these effects may lead to an increase in sheet bulk and thickness.

For scalenohedral PCC (an example of microporous inorganic particulate material), the impact of agglomeration on strength can be offset to some extent by controlling the particle size distribution within a narrow range (thereby eliminating ultrafine particles that are very detrimental to paper strength) and using a median particle size that is larger than the particle size that is optimal for light scattering. However, if the size of the particles or agglomerates is too large, the light scattering efficiency is lost.

Microfibrillated cellulose

Various methods of producing microfibrillated cellulose ("MFC") are known in the art. Certain methods and compositions comprising microfibrillated cellulose produced by the milling procedure are described in WO-A-2010/131016. Husband, j.c., svinding, p., skuse, d.r., motsi, t., likitalo, m., coles, a., fiberLean Technologies ltd, 2015, "Paper filler composition," PCT international application No. WO-A-2010/131016, the contents of which are hereby incorporated by reference in their entirety. MFC produced by the milling process may include co-milling cellulose-containing fibers with an inorganic particulate material. Alternatively, MFC may be produced by grinding cellulose fibers in the presence of a grinding medium other than an inorganic particulate material. Paper products comprising such microfibrillated cellulose have shown excellent paper properties such as paper burst strength and tensile strength. The method described in WO-A-2010/131016 also enables microfibrillated cellulose to be produced economically.

WO2010/131016 describes a milling procedure for producing microfibrillated cellulose with or without inorganic particulate material. This milling procedure is described below. In one embodiment of the method set forth in WO-A-2010/131016, the method utilizes mechanical disintegration of cellulose fibers without cellulose pretreatment to cost-effectively and mass produce microfibrillated cellulose ("MFC"). One embodiment of the method uses a stirred media crumb mill milling technique that disintegrates the fiber into MFC by stirring the milled media beads. In this process, minerals such as calcium carbonate or kaolin are added as grinding aids, greatly reducing the energy required. Husband, j.c., svening, p., skuse, d.r., motsi, t., likitalo, m., coles, a., fiberLean Technologies ltd, 2015, "Paper filler composition," U.S. patent No. 9127405B2, which is hereby incorporated by reference.

Despite the foregoing advances, there remains a need to optimize paper filler compositions comprising MFC and inorganic particulate materials by judicious selection and control of the particle size and particle size distribution of the inorganic particulate materials to maintain sufficiently low porosity, high brightness and opacity, and wet and dry strength characteristics, including minimum tensile strength, burst strength, and tear strength, as well as tensile strength of paper and paperboard in the "Z" direction (perpendicular to the paper plane), and to resist damage during printing and paper processing (converting process), while optimizing bending resistance and sheet bulk (bulk) or thickness.

Disclosure of Invention

From the description, drawings, examples and claims of this specification, the inventors have discovered a method of making paper and paperboard with improved mechanical properties by making and using MFC and one or more microporous inorganic particulate materials based on the particle size and particle size distribution of the one or more microporous inorganic particulate materials.

The present invention is based on the use of microfibrillated cellulose and microporous inorganic particulate material added to a papermaking furnish to produce paper and paperboard with enhanced mechanical properties that are not significantly reduced or maintained or even improved when MFC and microporous inorganic particulate material combinations are used instead of MFC and conventional inorganic particulate materials alone. The microfibrillated cellulose and microporous inorganic particulate material may be added to the papermaking furnish alone or as a filler composition comprising MFC and one or more microporous inorganic particulate materials.

The inventors have surprisingly found that the use of MFC in combination with one or more microporous inorganic particulate materials (i.e., inorganic particulate materials having coarser (larger) than conventional particle and agglomerate sizes) can allow for a substantial increase in the inorganic particulate material content of the drawing sheet while maintaining the desired strength, bulk, stiffness and porosity characteristics. The bulk and stiffness losses caused by the use of MFC are offset by the high bulk contribution of one or more microporous inorganic particulate materials, and the strength losses caused by the use of high content microporous inorganic particulate materials are offset by the use of MFC. MFC also counteracts the typical increase in porosity associated with microporous inorganic particulate materials, and the increase in MFC and microporous inorganic particulate material content counteracts the loss of light scattering efficiency associated with using microporous inorganic particulate materials that are coarser than optimal.

According to various aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials include a median particle size (d ₅₀ ) In the range of about 3 μm to about 50 μm, such as, for example, from about 5 μm to about 30 μm, from about 10 μm to about 30 μm, from about 15 μm to about 25 μm, from about 20 μm to about 30 μm, from about 3 μm to about 15 μm, from about 5 μm to about 10 μm, from about 2 μm to about 6 μm, and particularly preferably between 3 μm and 6 μm (as measured by sedimentation methods described herein and known in the art), and agglomerates of coarse-particle size microporous inorganic particulate material.

Also in accordance with various aspects and embodiments of the present disclosure, the term mechanical properties includes one or more of tensile elongation, tensile stiffness, bulk, and flexural stiffness. The foregoing characteristics may be measured by methods described herein and well known in the art of making paper and paperboard.

In one aspect of the present disclosure, a paper or paperboard filler composition is disclosed that comprises microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials and is used for addition to a papermaking furnish used to make paper or paperboard, wherein the MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without the MFC and the one or more microporous inorganic particulate materials.

In another aspect of the present disclosure, a paper or paperboard filler composition is disclosed that comprises microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials and is used in a process for preparing a papermaking furnish for making paper or paperboard, wherein the MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to a paper and paperboard product made from the same papermaking furnish without MFC and the one or more microporous inorganic particulate materials.

In another aspect of the present disclosure, a paper or paperboard filler composition is disclosed comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials and for addition to a papermaking furnish used to make paper or paperboard, wherein MFC is obtained by a co-milling process using the same or different microporous inorganic particulate materials and/or conventional non-agglomerated inorganic particulate materials and a cellulosic containing fibrous substrate; and wherein the MFC and the one or more microporous inorganic particulate materials impart mechanical properties to the paper or paperboard with improved mechanical properties compared to paper and paperboard products made from the same papermaking furnish without the MFC and the one or more microporous inorganic particulate materials.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials comprise (or are selected from the group consisting of): calcined clay, kaolin, kaolinite, amorphous aluminum silicate, scalenohedral precipitated calcium chloride, aragonite precipitated calcium carbonate, chemically aggregated filler material, diatomaceous earth, and ground expanded perlite.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials comprise (or consist essentially of or consist of) calcined clay.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials comprise (or consist essentially of or consist of) kaolin.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials comprise (or consist essentially of or consist of) kaolinite.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials comprise (or consist essentially of or consist of) amorphous aluminum silicate.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials comprise (or consist essentially of) scalenohedral precipitated calcium carbonate.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials comprise (or consist essentially of or consist of) aragonite precipitated calcium carbonate.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials comprise (or consist essentially of or consist of) chemically aggregated filler material.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials comprise (or consist essentially of or consist of) diatomaceous earth.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials comprise (or consist essentially of or consist of) ground expanded perlite.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, MFC and the one or more microporous inorganic particulate materials may be added separately or may be added together as a filler composition into the papermaking furnish.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the papermaking furnish comprises one or more pulps (pulps) selected from softwood pulps.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the softwood pulp is selected from (or selected from the group consisting of): spruce, pine, fir, larch and hemlock, and mixed softwood pulp.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the papermaking furnish comprises one or more pulps selected from (or selected from the group consisting of) hardwood pulp.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the hardwood pulp is selected from (or selected from the group consisting of): eucalyptus, aspen (aspen) and birch, and mixed hardwood pulp.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the pulp source of the papermaking furnish is selected from (or consists essentially of or consists of) the following: eucalyptus pulp, spruce pulp, pine pulp, beech pulp, hemp pulp, cotton pulp, acacia and mixtures thereof.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the pulp source of the papermaking furnish is selected from (or consists essentially of or consists of) the following: nordic pine, black spruce, radiata pine, southern pine, enzyme-treated Nordic pine (Enzyme-Treated Nordic Pine), douglas fir, dissolving Pulp (Dissonving Pulp), birch (including birch #1, birch #2 described herein), eucalyptus, acacia, mixed European hardwood (Mixed European Hardwood), mixed Thailand hardwood, recycled paper, cotton, abaca, acacia, sisal, bagasse, kenaf, miscanthus, sorghum, arundo (Giantreed) and flax.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the mechanical property is selected from one or more of tensile strength, tensile elongation, bulk, tensile stiffness, flexural stiffness, porosity, burst, tear strength, and tensile strength in the "Z" direction.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the mechanical property is tensile strength.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the mechanical property is tensile elongation.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the mechanical property is bulk.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the mechanical property is tensile stiffness.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the mechanical property is flexural rigidity.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the mechanical property is porosity.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the mechanical property is burst.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the mechanical property is tear strength.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the mechanical property is tensile strength in the "Z" direction.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the microfibrillated cellulose has a modal fiber particle size (modal fibre particle size) ranging from about 0.1 μm to 500 μm.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the microfibrillated cellulose has a modal fiber particle size of at least about 0.5 μm, at least about 10 μm, at least about 50 μm, at least about 100 μm, at least about 150 μm, at least about 200 μm, at least about 300 μm, or at least about 400 μm.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the median particle size (d ₅₀ ) Ranging from about 3 μm to about 50 μm, from about 5 μm to about 30 μm, from about 10 μm to about 30 μm, from about 15 μm to about 25 μm, from about 20 μm to about 30 μm, from about 3 μm to about 15 μm, from about 5 μm to about 10 μm, from about 3 μm to about 6 μm, or from about 3 to about 5 μm.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials and microfibrillated cellulose composite may be combined with one or more dispersants, such as those selected from the group comprising (or selected from the group consisting of): homopolymers or copolymers of polycarboxylic acids and/or salts or derivatives thereof, based on esters of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid; acrylamide or acrylate, methyl methacrylate or mixtures thereof; alkaline polyphosphates, phosphonic, citric and tartaric acids and salts or esters thereof; and mixtures thereof.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials and the microfibrillated cellulose composite are provided in the form of a powder.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials and the microfibrillated cellulose composite are provided in the form of a suspension or an aqueous suspension, and in alternative embodiments, the aqueous suspension is a pumpable liquid.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, wherein the one or more microporous inorganic particulate materials comprise a blend of the first and second microporous inorganic particulate materials, the weight ratio of the first microporous inorganic particulate material to the second microporous inorganic particulate material may range from about 10:90 to about 90:10, or from about 20:80 to about 80:20, or from about 25:75 to about 75:25, or from about 40:60 to about 60:40, or about 50:50.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the adhesive composition further comprises an adhesive, and in one embodiment, may be an inorganic or organic adhesive. In other embodiments, the binder may be an alkali metal silicate, such as sodium silicate or potassium silicate.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the weight ratio of microfibrillated cellulose of the binder composition to the one or more microporous inorganic particulate materials is 1:5 to 5:1, or 1:3 to 3:1, or 1:2 to 2:1, or 1:1.5 to 1.5 to 1, or 1:1 on a dry weight basis.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the total content of the one or more microporous inorganic particulate materials is present in an amount of 10 wt% to 95 wt%, or 15 wt% to 90 wt%, or 20 to 75 wt%, or 25 wt% to 67 wt%, or 33 to 50 wt%, based on the dry weight of the filler composition.

In another aspect of the present disclosure, a method of preparing a papermaking furnish comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials is disclosed, the method comprising the steps of:

adding one or more microporous inorganic particulate materials to a papermaking furnish;

adding MFC to a papermaking furnish; wherein MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without microfibrillated cellulose and the one or more microporous inorganic particulate materials.

adding MFC to a papermaking furnish; wherein MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose; and wherein MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without microfibrillated cellulose and the one or more microporous inorganic particulate materials.

adding a filler composition comprising MFC and one or more microporous inorganic particulate materials to a papermaking furnish; wherein MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without microfibrillated cellulose and the one or more microporous inorganic particulate materials.

In another aspect of the present disclosure, a papermaking furnish comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials is disclosed, the method comprising the steps of:

adding a filler composition comprising MFC and one or more microporous inorganic particulate materials to a papermaking furnish; wherein MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose; and wherein MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without microfibrillated cellulose and the one or more microporous inorganic particulate materials.

In another aspect of the present disclosure, a paper or paperboard made from a papermaking furnish comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials is disclosed, the method comprising the steps of:

adding a filler composition comprising MFC and one or more microporous inorganic particulate materials to a papermaking furnish; wherein the filler composition imparts improved mechanical properties to the paper or paperboard compared to paper and paperboard products made from the same papermaking furnish without MFC and one or more microporous inorganic particulate materials.

A method of making paper or paperboard having improved mechanical properties, the method comprising the steps of: preparing a papermaking furnish for producing paper or paperboard; adding one or more microporous inorganic particulate materials to a papermaking furnish; adding microfibrillated cellulose (MFC) to a papermaking furnish; wherein MFC and the one or more microporous inorganic particulate materials are added to the papermaking furnish alone or as a filler composition comprising MFC and the one or more microporous inorganic particulate materials; producing paper or paperboard from a papermaking furnish by dewatering and drying the papermaking furnish; wherein MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without MFC and microporous inorganic particulate materials.

In another aspect of the present disclosure, there is a method of making paper or paperboard from a papermaking furnish comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials, the method comprising the steps of:

adding a filler composition comprising MFC and one or more microporous inorganic particulate materials to a papermaking furnish; wherein MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose; and wherein the filler composition imparts improved mechanical properties to the paper or paperboard compared to paper and paperboard products made from the same papermaking furnish without MFC and one or more microporous inorganic particulate materials. In one embodiment, MFC and the one or more microporous inorganic particulate materials are added to the papermaking furnish alone or as a filler composition comprising MFC and the one or more microporous inorganic particulate materials.

adding MFC to a papermaking furnish; wherein MFC and the one or more microporous inorganic particulate materials impart mechanical properties to the paper or paperboard with improved mechanical properties compared to paper and paperboard products made from the same papermaking furnish without microfibrillated cellulose and the one or more microporous inorganic particulate materials. In one embodiment, MFC and the one or more microporous inorganic particulate materials are added to the papermaking furnish alone or as a filler composition comprising MFC and the one or more microporous inorganic particulate materials.

adding MFC to a papermaking furnish;

Wherein MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose; and wherein MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without MFC and the one or more microporous inorganic particulate materials. In one embodiment, MFC and the one or more microporous inorganic particulate materials are added to the papermaking furnish alone or as a filler composition comprising MFC and the one or more microporous inorganic particulate materials.

In another aspect of the present disclosure, there is a method of making paper or paperboard having improved mechanical properties, the method comprising the steps of: preparing a papermaking furnish for producing paper or paperboard; preparing a filler composition comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials; adding a filler composition to a papermaking furnish; producing paper or paperboard from a papermaking furnish by dewatering and drying the papermaking furnish; wherein the filler composition imparts improved mechanical properties to the paper or paperboard compared to paper and paperboard products made from the same papermaking furnish without MFC and microporous inorganic particulate material. In one embodiment, MFC and the one or more microporous inorganic particulate materials are added to the papermaking furnish alone or as a filler composition comprising MFC and the one or more microporous inorganic particulate materials.

In another aspect of the present disclosure, there is a method of making paper or paperboard having improved mechanical properties, the method comprising the steps of: preparing a papermaking furnish for producing paper or paperboard; preparing a filler composition comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials; adding a filler composition to a papermaking furnish; producing paper or paperboard from a papermaking furnish by dewatering and drying the papermaking furnish; wherein MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose; and wherein the filler composition imparts improved mechanical properties to the paper or paperboard from MFC-free and one. In one embodiment, MFC and the one or more microporous inorganic particulate materials are added to the papermaking furnish alone or as a filler composition comprising MFC and the one or more microporous inorganic particulate materials.

In another aspect of the present disclosure, there is a method of making paper or paperboard having improved mechanical properties, the improvement comprising: preparing a papermaking furnish for producing paper or paperboard; adding one or more microporous inorganic particulate materials to a papermaking furnish; adding microfibrillated cellulose (MFC) to a papermaking furnish; producing paper or paperboard from a papermaking furnish by dewatering and drying the papermaking furnish; wherein MFC and one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without MFC and microporous inorganic particulate materials. In one embodiment, MFC and the one or more microporous inorganic particulate materials are added to the papermaking furnish alone or as a filler composition comprising MFC and the one or more microporous inorganic particulate materials.

In another aspect of the present disclosure, there is a method of making paper or paperboard having improved mechanical properties, the improvement comprising: preparing a papermaking furnish for producing paper or paperboard; adding one or more microporous inorganic particulate materials to a papermaking furnish; adding microfibrillated cellulose (MFC) to a papermaking furnish; producing paper or paperboard from a papermaking furnish by dewatering and drying the papermaking furnish; wherein MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose; and wherein MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without MFC and the one or more microporous inorganic particulate materials. In one embodiment, MFC and the one or more microporous inorganic particulate materials are added to the papermaking furnish alone or as a filler composition comprising MFC and the one or more microporous inorganic particulate materials.

In additional embodiments of the foregoing aspects and embodiments of the present disclosure, the one or more microporous inorganic particulate materials are selected from the group comprising (or from the group consisting of): calcined clay, kaolin, kaolinite, amorphous aluminum silicate, scalenohedral precipitated calcium chloride, aragonite precipitated calcium carbonate, chemically aggregated filler material, diatomaceous earth, or ground expanded perlite.

In one embodiment, the one or more microporous inorganic particulate materials comprise or are calcined clays.

In one embodiment, the one or more microporous inorganic particulate materials comprise or are kaolin.

In one embodiment, the one or more microporous inorganic particulate materials comprise or are kaolinite.

In one embodiment, the one or more microporous inorganic particulate materials comprise or are amorphous aluminum silicate.

In one embodiment, the one or more microporous inorganic particulate materials comprise or are scalenohedral precipitated calcium carbonate.

In one embodiment, the one or more microporous inorganic particulate materials comprise or are aragonite precipitated calcium carbonate.

In one embodiment, the one or more microporous inorganic particulate materials comprise or are chemically aggregated filler materials.

In one embodiment, the one or more microporous inorganic particulate materials comprise or are diatomaceous earth.

In one embodiment, the one or more microporous inorganic particulate materials comprise or are ground expanded perlite.

In one embodiment of aspects of the present disclosure, the papermaking furnish comprises one or more pulps selected from softwood pulps.

In one embodiment of aspects of the present disclosure, the softwood pulp is selected from (or selected from the group consisting of): spruce, pine, fir, larch and hemlock, or mixed softwood pulp.

In one embodiment of aspects of the disclosure, the hardwood pulp is selected from (or selected from the group consisting of): eucalyptus, aspen and birch, or mixed hardwood pulp.

In one embodiment of aspects of the present disclosure, the pulp source of the papermaking furnish is selected from (or from the group consisting of): eucalyptus pulp, spruce pulp, pine pulp, beech pulp, hemp pulp, acacia, cotton pulp and mixtures thereof.

In one embodiment of aspects of the present disclosure, the pulp source of the papermaking furnish is selected from (or from the group consisting of): north European pine, black spruce, radiata pine, southern pine, enzyme treated North European pine, douglas fir, dissolving pulp, birch (including birch #1, birch #2, described herein), eucalyptus, acacia, mixed European hardwood, mixed Thailand hardwood, recycled paper, cotton, abaca, sisal, bagasse, kenaf, miscanthus, sorghum, arundo, and flax.

In one embodiment of aspects of the present disclosure, microfibrillated cellulose is prepared by a co-milling process using one or more non-agglomerated inorganic particulate materials and one or more microporous inorganic particulate material composites used to prepare microfibrillated cellulose.

In one embodiment of aspects of the present disclosure, the microfibrillated cellulose has a fiber steepness of about 20 to about 50.

In one embodiment of aspects of the present disclosure, the microfibrillated cellulose has a d ranging from about 5 to about 500 μm as measured by laser light scattering ₅₀ 。

In one embodiment of aspects of the disclosure, the microfibrillated cellulose has a d equal to or less than about 400 μm as measured by laser light scattering ₅₀ 。

In one embodiment of aspects of the disclosure, the microfibrillated cellulose has a d equal to or less than about 200 μm as measured by laser light scattering ₅₀ 。

At the bookIn one embodiment of the disclosed aspects, the microfibrillated cellulose has a d equal to or less than about 200 μm as measured by laser light scattering ₅₀ 。

In one embodiment of aspects of the disclosure, the microfibrillated cellulose has a d equal to or less than about 150 μm as measured by laser light scattering ₅₀ 。

In one embodiment of aspects of the present disclosure, the one or more microporous inorganic particulate materials and the microfibrillated cellulose composite are provided in the form of a powder.

In one embodiment of aspects of the present disclosure, the one or more microporous inorganic particulate materials and the microfibrillated cellulose composite are provided in the form of a suspension. In another embodiment, the suspension may be an aqueous suspension. In a further embodiment, the aqueous suspension is a pumpable liquid.

In one embodiment of aspects of the present disclosure, the one or more microporous inorganic particulate materials comprise a blend of first and second microporous inorganic particulate materials, wherein the weight ratio of the first microporous inorganic particulate material to the second microporous inorganic particulate material may range from about 10:90 to about 90:10, from about 20:80 to about 80:20, or from about 25:75 to about 75:25, or from about 40:60 to about 60:40, or about 50:50.

In one embodiment of aspects of the disclosure, the method further comprises an adhesive. In another embodiment, the binder is an organic or inorganic binder. In a further embodiment, the binder is an alkali metal silicate, such as sodium silicate or potassium silicate.

In further embodiments of aspects of the disclosure, the weight ratio of microfibrillated cellulose to the one or more microporous inorganic particulate materials on a dry weight basis is 1:5 to 5:1, or 1:3 to 3:1, or 1:2 to 2:1, or 1:1.5 to 1.5 to 1, or about 1:1.

In further embodiments of aspects of the present disclosure, the total content of the one or more microporous inorganic particulate materials is present in an amount of 10 wt% to 95 wt%, 15 wt% to 90 wt%, or 20 to 75 wt%, or 25 wt% to 67 wt%, or 33 to 50 wt%, based on the dry weight of the filler composition.

Unless otherwise indicated, the particle size characteristics referred to herein for inorganic particulate materials are as measured using a Sedigraph5100 machine (referred to herein as "Micromeritics Sedigraph5100 unit") supplied by Micromeritics Instruments Corporation, norcross, ga., USA (telephone: +17706623620; web site: www.micromeritics.com), in a well known manner by sedimentation of the particulate material in a fully dispersed state in an aqueous medium. Such a machine provides a measured value and cumulative weight percent curve for particles having a size less than a given e.s.d. value, which is known in the art as the "equivalent spherical diameter" (e.s.d.). Average particle size d ₅₀ Is the value of the particle e.s.d measured in this way, at which 50% by weight of the particles have a value less than d ₅₀ Equivalent sphere diameter of the values.

In one embodiment of aspects of the present disclosure, the blend of the first and second inorganic particulate materials and the binder solution may be mixed with sufficient agitation to at least substantially uniformly distribute the binder composition (slurry or suspension) among the contact agglomeration points of the blend of the first and second inorganic particulate materials without damaging the structure of the first or second inorganic particulate materials.

In one embodiment of aspects of the disclosure, the contacting is performed in a low shear mixing device.

In one embodiment of aspects of the present disclosure, the mixing may be performed at about room temperature (i.e., about 20 ℃ to about 23 ℃).

In one embodiment of aspects of the present disclosure, the mixing may be performed at about room temperature (i.e., about 20 ℃ to about 50 ℃).

In one embodiment of aspects of the present disclosure, the mixing may be performed at about room temperature (i.e., about 30 ℃ to about 45 ℃).

In one embodiment of aspects of the present disclosure, the mixing may be performed at about room temperature (i.e., about 35 ℃ to about 45 ℃).

In one embodiment of aspects of the present disclosure, the contacting may include spraying the blend of the first and/or first and second inorganic particulate materials with the binder composition (slurry or suspension).

In one embodiment of aspects of the disclosure, the contacting is intermittent.

In one embodiment of aspects of the disclosure, the contacting is continuous.

In one embodiment of aspects of the present disclosure, the binder may be present in the binder composition (slurry or suspension) in an amount of less than about 40 wt% relative to the weight of the binder solution. In some embodiments, the binder may range from about 1 wt% to about 10 wt%.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that any of the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other means for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It should be expressly understood, however, that any description, drawings, examples, etc. are provided for the purpose of illustration and description only and are not intended as a definition of the limits of the present invention.

Drawings

For a more complete understanding of the principles disclosed herein and the advantages thereof, reference is made to the following description taken in conjunction with the accompanying drawings in which:

fig. 1 is a graph of scott bond (ScottBond), flexural rigidity, tensile index, bulk volume (Bulk), and light scattering properties of a composition comprising 20% and 30% of Ground Calcium Carbonate (GCC) composition with and without MFC compared to a 20% and 30% of Precipitated Calcium Carbonate (PCC) composition with and without MFC.

FIG. 2 is a graph of flexural rigidity in mN.m compared to percent filler fraction comprising PCC (the remainder being GCC).

FIG. 3 is a graph in cm ² g ^-1 A plot of the light scattering coefficient in units (F10) versus the percentage filler fraction comprising PCC (the remainder being GCC).

FIG. 4 is a graph of tensile index in N.m/g versus percent filler fraction comprising PCC (the remainder being GCC).

FIG. 5 is a graph of J/m ² Plot of scott bond in units versus percent filler ratio comprising PCC (balance GCC).

FIG. 6 is a plot of tensile index in N.m/g versus sheet filler content expressed as percent PCC content.

Fig. 7 is a graph of light scattering (F10S) versus sheet filler content expressed as percent PCC content.

FIG. 8 is a plot of flexural rigidity in mN versus sheet filler content expressed as percent PCC content.

Detailed Description

The names (title), headings, and sub-headings provided herein are not to be construed as limiting aspects of the disclosure. Accordingly, by referring to the specification as a whole, the terms defined below may be more fully defined. All references cited herein are incorporated by reference in their entirety.

The present invention relates to a filler composition comprising MFC and one or more microporous inorganic particulate material composites for use in a papermaking furnish for producing paper and paperboard having improved mechanical properties compared to paper and paperboard produced without MFC and one or more microporous inorganic particulate materials.

Definition and title

Unless otherwise defined, scientific and technical terms used herein will have the meanings commonly understood by one of ordinary skill in the art. In addition, unless the context requires otherwise, singular terms shall include the plural and plural terms shall include the singular.

In this application, unless otherwise stated, the use of "or" means "and/or". In the context of multiple dependent claims, the use of "or" means that more than one preceding independent claim or dependent claim is traced back only in an alternative manner.

The use of the word "a/an" when used in conjunction with the term "comprising" may mean "one" but it also corresponds to the meaning of "one" or more "," at least one "and" one "or more". The term "or" is used to mean "and/or" unless explicitly indicated to refer to alternatives only when alternatives are mutually exclusive, but the disclosure supports definitions of alternatives and "and/or". Throughout this application, the term "about" is used to indicate that the value includes a quantitative device, an inherent error change in the method used to determine the value, or a change that exists between subjects. For example, and without limitation, when the term "about" is used, the specified value may vary by plus or minus twelve percent, or eleven percent, or ten percent, or nine percent, or eight percent, or seven percent, or six percent, or five percent, or four percent, or three percent, or two percent, or one percent. The use of the term "at least one" will be understood to include one as well as any amount of more than one, including but not limited to 1, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 100, etc. The term "at least one" may extend to 100 or 1000 or more, depending on the term to which it is attached. Furthermore, an amount of 100/1000 should not be considered limiting, as lower or higher limits may also yield satisfactory results. Furthermore, the use of the term "at least one of X, Y and Z" will be understood to include any combination of X alone, Y alone, and Z alone, and X, Y and Z.

Ordinal terms (i.e., "first," "second," "third," "fourth," etc.) are used merely for the purpose of distinguishing between two or more items and are not intended to imply any order or sequence or importance of one item relative to another or any order of addition unless otherwise indicated.

As used herein, the term one or more microporous inorganic particulate materials includes a median particle size (d ₅₀ ) Coarse-grained inorganic particulate material and coarse-grained inorganic particulate material agglomerates ranging from about 3 μm to about 50 μm, such as, for example, from about 5 μm to about 30 μm, from about 10 μm to about 30 μm, from about 15 μm to about 25 μm, from about 20 μm to about 30 μm, from about 3 μm to about 15 μm, from about 5 μm to about 10 μm, from about 2 μm to about 6 μm, and particularly preferably between 3 μm and 6 μm (as measured by sedimentation methods described herein and known in the art).

As used herein, the terms "comprising," "including," "having," "including," "containing," or "containing" are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. In addition, the term "comprising" is also understood to be able to be used in conjunction with the term "consisting of … …" or "consisting essentially of … …". Similarly, the phrase "selected from" and words of similar meaning may also include the phrase "selected from the group consisting of … …".

As used herein, the term "include" and grammatical variants thereof are intended to be non-limiting such that recitation of items in a list is not to the exclusion of other like items that may be substituted for or added to the listed items.

The cellulosic-containing fibrous substrate (variously referred to herein as "cellulosic-containing fibrous substrate", "cellulosic fibers", "fibrous cellulosic feedstock", "cellulosic feedstock", and "cellulose-containing fibers (or fibrous)", etc.) may be derived from virgin or recycled pulp or paper mill broke and/or industrial waste, or a paper stream from a paper mill that is rich in mineral fillers and cellulosic materials.

As used herein, mechanical properties include one or more of the following: tensile strength, tensile elongation, bulk, tensile stiffness, flexural stiffness, porosity, tensile, burst, tear strength, and tensile strength in the "Z" direction.

As used herein, the term "substantially" means that the event or circumstance described subsequently occurs entirely or to a substantial extent. For example, when related to a particular event or circumstance, the term "substantially" means that the event or circumstance described subsequently occurs at least 80% of the time, or at least 85% of the time, or at least 90% of the time, or at least 95% of the time. Conversely, when used in reference to a mechanical property such as "no substantial decrease" in tensile strength and/or flexural rigidity or similar language, the decrease in tensile strength and/or flexural rigidity is not more than 15%, or more than 10% or more than 5% less than the property of the control.

As used herein, the phrase "an integer from X to Y" is meant to include any integer of endpoints. For example, the phrase "an integer from 1 to 5" means 1, 2, 3, 4, or 5.

Microfibrillated cellulose

Although microfibrillated cellulose (MFC) is well known and described in the art, for the purpose of one or more of the presently disclosed and/or claimed inventive concepts microfibrillated cellulose is defined as cellulose consisting of isolated cellulose microfibrils and/or microfibrils in the form of cellulose microfibril bundles, both of which are derived from cellulosic raw materials. Microfibrillated cellulose is thus understood to include partially or fully fibrillated cellulose or lignocellulose fibers, which can be achieved by various methods known in the art.

As used herein, "microfibrillated cellulose" may be used interchangeably with "microfibrillated cellulose (microfibrillar cellulose)", "nanofibrillated cellulose", "cellulose nanofibers", "nanofibrillated cellulose microfibers" and/or simply "MFC". In addition, as used herein, the term listed above interchangeably with "microfibrillated cellulose" may refer to cellulose that has been fully fibrillated or cellulose that has been substantially microfibrillated but still contains an amount of non-microfibrillated cellulose that does not interfere with the benefits of microfibrillated cellulose as described and/or claimed herein.

"microfibrillating" means a process in which microfibrils of cellulose are released or partially released as individual substances or as small aggregates, as compared to the fibers of a pre-fibrillated pulp. Typical cellulosic fibers suitable for use in papermaking (i.e., pre-fibrillated pulp) include large aggregates of hundreds or thousands of individual cellulosic fibers.

Microfibrillated cellulose comprises cellulose, which is a naturally occurring polymer comprising repeating glucose units. The term "microfibrillated cellulose" as used in this specification is also denoted MFC, including microfibrillated/microfibrillated cellulose and nanofibrillated cellulose (nano-fibrillated cellulose)/nanofibrillated cellulose (nanofibrillar cellulose) (NFC), these materials are also referred to as nanocellulose.

Microfibrillated cellulose is prepared by stripping off the outer layer of cellulose fibers which may have been exposed by mechanical shearing, with or without prior enzymatic or chemical treatment. There are many methods known in the art for preparing microfibrillated cellulose.

In a non-limiting example, the term microfibrillated cellulose is used to describe fibrillated cellulose comprising nano-sized cellulose particle fibers or fibrils typically having at least one dimension less than 100 nm. When released from cellulose fibers, fibrils generally have a diameter of less than 100 nm. The actual diameter of the cellulose fibrils depends on the source and the method of manufacture.

The particle size distribution and/or aspect ratio (length/width) of the cellulose microfibrils attached to fibrillated cellulose fibers or as released microfibrils depends on the source and the manufacturing method used in the microfibrillation process.

In a non-limiting example, the aspect ratio of the microfibers is generally high, and individual microfibers may be greater than 1 micron in length and may range in diameter from about 5 to 60nm, with number average diameters generally less than 20nm. The microfiber bundles may be greater than 1 micron in diameter, but are typically less than 1 micron in diameter.

In a non-limiting example, the smallest fibrils are conventionally referred to as base fibrils (elementary fibril), which typically have a diameter of about 2-4 nm. Base fibril aggregation is also common, which can also be considered as microfibers.

In a non-limiting example, the microfibrillated cellulose may comprise, at least in part, nanocellulose. Nanocellulose may mainly comprise nano-sized fibrils having a diameter of less than 100nm and a length that may be in the micrometer range or less. The smallest microfibrils resemble so-called basal fibrils, which are usually 2 to 4nm in diameter. Of course, the size and structure of the microfibers and microfiber bundles depend on the raw materials used, in addition to the method of producing microfibrillated cellulose. Nonetheless, those of ordinary skill in the art will appreciate the meaning of "microfibrillated cellulose" in the context of one or more of the presently disclosed and/or claimed inventive concepts.

The length of the fibrils may vary, typically from about 1 to greater than 10 microns, depending on the source of the cellulose fibers and the manufacturing process used to microfibrillate the cellulose fibers.

The coarse MFC grade may contain a substantial portion of fibrillated fibers, i.e. fibrils protruding from the tracheids (cellulose fibers), and a certain amount of fibrils released from the tracheids (cellulose fibers).

In one embodiment, microfibrillated cellulose may also be produced from recycled pulp or paper mill broke and/or industrial waste, or paper streams from paper mills rich in mineral fillers and cellulose materials.

The fibrous substrate comprising cellulose may be added to the milling vessel in a dry state. For example, the dried broke may be added directly to the mill vessel. The aqueous environment in the mill vessel will promote pulp formation.

Co-milling process of microfibrillated cellulose and inorganic particulate material

In one embodiment, the present invention relates to modifications, e.g., improvements, to the methods and compositions described in WO-A-2010/131016, the entire contents of which are hereby incorporated by reference.

WO-A-2010/131016 discloses A process for preparing microfibrillated cellulose comprising microfibrillating A fibrous material comprising cellulose, e.g. by grinding, optionally in the presence of A grinding medium and an inorganic particulate material. When used as filler in paper, for example as a substitute or partial substitute for conventional mineral fillers, it has surprisingly been found that microfibrillated cellulose obtained by the process, optionally in combination with inorganic particulate materials, improves the burst strength properties of the paper. That is, it was found that the paper filled with microfibrillated cellulose has improved burst strength relative to paper filled with mineral filler alone. In other words, microfibrillated cellulose filler was found to have paper burst strength enhancing properties. In a particularly advantageous embodiment of the invention, the fibrous material comprising cellulose is milled in the presence of a milling medium optionally in combination with an inorganic particulate material to obtain microfibrillated cellulose having a fiber steepness of 20 to about 50.

Co-treatment of fibrous substrates comprising cellulose and at least one inorganic particulate material

As used herein, the term "co-grinding (or" co-ground ") composite of microfibrillated cellulose and inorganic particulate material" refers to a composite obtained by a "co-grinding microfibrillation process" in which a fibrous substrate comprising cellulose is microfibrillated in the presence of at least one inorganic particulate material and optionally a grinding medium other than the at least one inorganic particulate material in an aqueous environment of a grinding apparatus (or in other words, by "co-treating" the fibrous substrate comprising cellulose in the presence of at least one inorganic particulate material and optionally in the presence of a grinding medium other than the at least one inorganic particulate material in a wet grinding apparatus to produce microfibrillated cellulose, the grinding medium being removed after grinding). See the description of exemplary microfibrillation and wet milling processes below.

After co-processing to form a co-processed microfibrillated cellulose and inorganic particulate material composite, additional inorganic particulate material may be added (e.g., by blending or mixing) to reduce the microfibrillated cellulose content of the co-processed microfibrillated cellulose and inorganic particulate material composite.

In one embodiment, MFC can be manufactured using a tower mill or a screen mill (such as a stirred media crumb mill).

A stirred media mill consists of a rotating impeller that imparts kinetic energy to small grinding media beads that grind a load via a combination of shear, compression, and impact forces. A variety of milling apparatuses can be used to produce MFC by the methods disclosed herein, including, for example, tower mills, screen mills, or stirred media chippers.

Microfibrillation process

According to another aspect and embodiment of the present disclosure, a method of microfibrillating a fibrous substrate comprising cellulose in the presence of at least one inorganic particulate material is provided. According to a particular embodiment of the present method, the microfibrillating step is carried out in the presence of an inorganic particulate material acting as a microfibrillating agent. According to another embodiment, the microfibrillating step is performed in the presence of inorganic particulate material and a grinding medium other than the at least one inorganic particulate material, the grinding medium being removed after grinding.

However, the microfibrillated cellulose used in the present invention is not limited to a single manufacturing method. Such a microfibrillation process is proposed for illustrative purposes.

"microfibrillated" means a process in which microfibrils of cellulose are released as individual substances or as small aggregates or partially released, as compared to fibers of pulp containing pre-fibrillated cellulose. Typical cellulosic fibers suitable for use in papermaking (i.e., pulp containing pre-fibrillated cellulose) include large aggregates of hundreds or thousands of individual cellulosic microfibers. By microfibrillating cellulose, specific features and characteristics are imparted to microfibrillated cellulose and compositions comprising microfibrillated cellulose and at least one inorganic particulate material, including but not limited to the features and characteristics described herein.

The microfibrillation step may be carried out in any suitable apparatus. In one embodiment, the microfibrillating step is performed in a milling vessel under wet milling conditions. In another embodiment, the microfibrillating step is performed in a homogenizer. Each of these embodiments is described in more detail below.

Wet milling microfibrillation process

The grinding may be a friction grinding process in the presence of a grinding medium or may be a autogenous grinding process, i.e. a grinding process carried out without a grinding medium. By grinding media is meant media other than at least one inorganic particulate material, which is co-ground with a fibrous substrate comprising cellulose.

When grinding media is present, it may be a natural or synthetic material. The grinding media may, for example, comprise spheres, beads or pills of any hard mineral, ceramic or metallic material. Such materials may include, for example, alumina, zirconia, zirconium silicate, aluminum silicate, or mullite-rich materials produced by calcining kaolinite clay at a temperature in the range of about 1300 ℃ to about 1800 ℃. For example, in some embodiments, use is made of

Grinding media. Alternatively, natural sand particles having a suitable particle size may be used. />

In general, the type and particle size of the grinding media to be selected for use in the present invention may depend on the characteristics, such as, for example, the particle size and chemical composition of the feed suspension of the material to be ground. Preferably, the particulate grinding media comprises particles having an average diameter in the range of about 0.1mm to about 6.0mm and more preferably in the range of about 0.2mm to about 4.0 mm. The grinding medium (or media) may be present in an amount up to about 70% by volume of the loaded material. The milling media may be present in an amount of at least about 10% by volume of the loaded material, such as at least about 20% by volume of the loaded material, or at least about 30% by volume of the loaded material, or at least about 40% by volume of the loaded material, or at least about 50% by volume of the loaded material, or at least about 60% by volume of the loaded material.

Grinding may be performed in one or more stages. For example, the coarse inorganic particulate material may be milled in a milling vessel to a predetermined particle size distribution, after which cellulosic containing fibrous material is added and milling continued until the desired level of microfibrillation is obtained. The coarse inorganic particulate material used in accordance with the first aspect of the present invention may initially have a particle size distribution wherein less than about 20% by weight of the particles have a basic sphere diameter (e.s.d) of less than 2 μm, for example less than about 15% by weight or less than about 10% by weight of the particles have an e.s.d of less than 2 μm. In another embodiment, the coarse inorganic particulate material used in accordance with the first aspect of the present invention may initially have a particle size distribution (as measured using a malvernmastersizer s machine) wherein less than about 20% by volume of the particles have an e.s.d. of less than 2 μm, for example less than about 15% by volume or less than about 10% by volume of the particles have an e.s.d. of less than 2 μm.

The coarse inorganic particulate material may be wet or dry milled with or without the presence of a milling medium. In the case of the wet milling stage, the coarse inorganic particulate material is preferably milled in an aqueous suspension in the presence of a milling medium. In such suspensions, the coarse inorganic particulate material may preferably be in an amount of from about 5% to about 85% by weight of the suspension; more preferably in an amount of about 20% to about 80% by weight of the suspension. Most preferably, the coarse inorganic particulate material may be present in an amount of from about 30% to about 75% by weight of the suspension. As described above, the coarse inorganic particulate material may be milled to a particle size distribution such that at least about 10 wt% of the particles have an e.s.d. of less than 2 μm, for example at least about 20 wt%, or at least about 30 wt%, or at least about 40 wt%, or at least about 50 wt%, or at least about 60 wt%, or at least about 70 wt%, or at least about 80 wt%, or at least about 90 wt%, or at least about 95 wt%, or about 100 wt% of the particles have an e.s.d. of less than 2 μm, after which the cellulose pulp is added, and the two components are co-milled to microfibrillate the fibers of the cellulose pulp.

In another embodiment, the coarse inorganic particulate material is milled to a particle size distribution (as measured using a malvernmastersizer s machine) such that at least about 10% by volume of the particles have an e.s.d less than 2 μm, for example at least about 20% by volume, or at least about 30% by volume, or at least about 40% by volume, or at least about 50% by volume, or at least about 60% by volume, or at least about 70% by volume, or at least about 80% by volume, or at least about 90% by volume, or at least about 95% by volume, or about 100% by volume of the particles have an e.s.d less than 2 μm, after which the cellulose pulp is added, and the two components are co-milled to microfibrillate the fibers of the cellulose pulp.

In one embodiment, the average particle size (d ₅₀ ) Reduced during co-milling. For example, d of inorganic particulate material ₅₀ Can be reduced by at least about 10% (as measured by the Malvern Mastersizer S machine), e.g., d of inorganic particulate material ₅₀ At least about 20% reduction, or at least about 30% reduction, or at least about 50% reduction, or at least about 60% reduction, or at least about 70% reduction, or at least about 80% reduction, or at least about 90% reduction may be achieved. For example, d before co-milling ₅₀ Is 2.5 μm and d after co-milling ₅₀ An inorganic particulate material of 1.5 μm will experience a particle size reduction of 40%. In certain embodiments, the average particle size of the inorganic particulate material is not significantly reduced during co-milling. "not significantly reduced" means d of inorganic particulate material ₅₀ Reduced by less than about 10%, e.g. d of inorganic particulate material ₅₀ The reduction is less than about 5%.

The fibrous substrate comprising cellulose may be microfibrillated in the presence of at least one inorganic particulate material to obtain a fiber having a d ranging from about 5 μm to about 500 μm as measured by laser light scattering ₅₀ Is used for the microfibrillated cellulose. The fibrous substrate comprising cellulose may be microfibrillated in the presence of inorganic particulate material to obtain a fibrous substrate having the following d ₅₀ Is a microfibrillated cellulose of (a): equal to or less than about 400 μm, such as equal to or less than about 300 μm, or equal to or less than about 200 μm, or equal to or less than about 150 μm, or equal to or less than about 125 μm, or equal to or less than about 100 μm, or equal to or less than about 90 μm,Or equal to or less than about 80 μm, or equal to or less than about 70 μm, or equal to or less than about 60 μm, or equal to or less than about 50 μm, or equal to or less than about 40 μm, or equal to or less than about 30 μm, or equal to or less than about 20 μm, or equal to or less than about 10 μm.

The fibrous substrate comprising cellulose may be microfibrillated in the presence of inorganic particulate material to obtain microfibrillated cellulose having a modal fiber particle size in the range of about 0.1-500 μm and a modal inorganic particulate material particle size in the range of 0.25-20 μm. The fibrous substrate comprising cellulose may be microfibrillated in the presence of inorganic particulate material to obtain microfibrillated cellulose having the following modal fiber particle size: at least about 0.5 μm, such as at least about 10 μm, or at least about 50 μm, or at least about 100 μm, or at least about 150 μm, or at least about 200 μm, or at least about 300 μm, or at least about 400 μm.

The fibrous substrate comprising cellulose may be microfibrillated in the presence of inorganic particulate material to obtain microfibrillated cellulose having a fiber steepness of equal to or greater than about 10 as measured by Malvern. The fiber steepness (i.e., steepness of the fiber particle size distribution) is determined by the following formula: steepness=100× (d ₃₀ /d ₇₀ )。

Microfibrillated cellulose may have a fiber steepness equal to or less than about 100. The microfibrillated cellulose may have a fiber steepness of equal to or less than about 75, or equal to or less than about 50, or equal to or less than about 40, or equal to or less than about 30. The microfibrillated cellulose may have a fiber steepness of about 20 to about 50, or about 25 to about 40, or about 25 to about 35, or about 30 to about 40.

Grinding is suitably carried out in a grinding vessel such as a roller mill (e.g., rod mill, ball mill, and autogenous mill), a stirred mill (e.g., SAM or IsaMill), a tower mill, a stirred media chipper (SMD), or a grinding vessel containing rotating parallel grinding plates between which the feed to be ground is fed.

In one embodiment, the milling vessel is a tower mill. The tower mill may include a stationary zone above one or more grinding zones. The quiescent zone is the zone located toward the top of the interior of the tower mill in which little or no grinding occurs and which contains microfibrillated cellulose and inorganic particulate material. The quiescent zone is the region in which grinding media particles settle into one or more grinding zones of the tower mill.

The tower mill may include a classifier above one or more grinding zones. In one embodiment, the classifier is mounted on top and located near the quiescent zone. The classifier may be a hydrocyclone.

The tower mill may include a screen above one or more grinding zones. In one embodiment, the screen is located near the quiescent zone and/or classifier. The screen may be sized to separate the grinding media from the aqueous suspension of product comprising microfibrillated cellulose and inorganic particulate material and enhance settling of the grinding media.

In one embodiment, the milling is performed under plug flow conditions. Under plug flow conditions, the flow through the column is such that mixing of the abrasive material through the column is limited. This means that at different points along the length of the tower mill, the viscosity of the aqueous environment will vary as the fineness of the microfibrillated cellulose increases. Thus, in practice, the grinding zone in a tower mill may be considered to include one or more grinding zones having a characteristic viscosity. Those skilled in the art will appreciate that there is no apparent boundary between adjacent grinding zones in terms of viscosity.

In one embodiment, water is added to the mill near the top of a stationary zone or classifier or screen above one or more of the milling zones to reduce the viscosity of the aqueous suspension comprising microfibrillated cellulose and inorganic particulate material in these zones in the mill. It has been found that by diluting the product microfibrillated cellulose and inorganic particulate material composite material at this point in the mill, the prevention of carrying of the grinding media to the quiescent zone and/or classifier and/or screen is improved. In addition, limited mixing through the column allows for treatment at the lower portion of the column at higher solids and dilution at the top, with limited reflux of dilution water to the lower portion of the column into one or more grinding zones. Any suitable amount of water effective to dilute the viscosity of the aqueous suspension of the product comprising microfibrillated cellulose and inorganic particulate material may be added. The water may be added continuously during the milling process, or periodically, or aperiodically.

In another embodiment, water may be added to the one or more grinding zones via one or more water injection points located along the length of the tower mill, or each water injection point may be located at a position corresponding to the one or more grinding zones. Advantageously, the ability to add water at various points along the tower allows for further adjustment of the grinding conditions at any or all locations along the mill.

The tower mill may include a vertical impeller shaft equipped with a series of impeller rotor disks throughout its length. The action of the impeller rotor disk creates a series of discrete grinding zones throughout the mill.

In another embodiment, the milling is performed in a screening mill (preferably a stirred media chipper). The screening mill may include one or more screens having a nominal pore size of at least about 250 μm, for example, the one or more screens may have a nominal pore size of at least about 300 μm, or at least about 350 μm, or at least about 400 μm, or at least about 450 μm, or at least about 500 μm, or at least about 550 μm, or at least about 600 μm, or at least about 650 μm, or at least about 700 μm, or at least about 750 μm, or at least about 800 μm, or at least about 850 μm, or at least about 900 μm, or at least about 1000 μm.

The screen sizes just mentioned above are applicable to the tower mill embodiments described above.

As described above, the grinding may be performed in the presence of a grinding medium. In one embodiment, the grinding media is a coarse media comprising particles having an average diameter in the range of about 1mm to about 6mm, such as about 2mm, or about 3mm, or about 4mm, or about 5 mm.

In another embodiment, the grinding media has a specific gravity of at least about 2.5, for example, at least about 3, or at least about 3.5, or at least about 4.0, or at least about 4.5, or at least about 5.0, or at least about 5.5, or at least about 6.0.

In another embodiment, the grinding media comprises particles having an average diameter in the range of about 1mm to about 6mm and a specific gravity of at least about 2.5.

As noted above, the grinding medium (or media) may be present in an amount up to about 70% by volume of the load material. The milling media may be present in an amount of at least about 10% by volume of the loaded material, such as at least about 20% by volume of the loaded material, or at least about 30% by volume of the loaded material, or at least about 40% by volume of the loaded material, or at least about 50% by volume of the loaded material, or at least about 60% by volume of the loaded material.

In one embodiment, the grinding media is present in an amount of about 50% by volume of the load material.

"load" means the composition added as feed to the mill vessel. The loading materials include water, grinding media, fibrous substrates comprising cellulose, and inorganic particulate materials, as well as any other optional additives as described herein. The use of relatively coarse and/or dense media has the advantage of increasing (i.e., faster) deposition rates and reducing media carryover through the quiescent zone and/or classifier and/or screen(s).

Another advantage of using a relatively coarse grinding medium is that during grinding, the average particle size (d ₅₀ ) May not be significantly reduced such that the energy imparted to the grinding system is primarily expended in microfibrillating the cellulosic-containing fibrous substrate.

Another advantage of using a relatively coarse screen is that a relatively coarse or dense grinding medium may be used in the microfibrillation step. Furthermore, the use of a relatively coarse screen (i.e., having a nominal pore size of at least about 250 um) allows for the processing and removal of relatively high solids content products from the mill, which allows for the processing of relatively high solids content feeds (including cellulosic-containing fibrous substrates and inorganic particulate materials) in an economically viable process. As discussed below, it has been found that a feed with a high initial solids content is desirable in terms of energy sufficiency. Furthermore, it was found that the product produced at a lower solids content (at a given energy) had a coarser particle size distribution.

Thus, according to one embodiment, the fibrous substrate comprising cellulose and the inorganic particulate material are present in an aqueous environment at an initial solids content of at least about 4wt.%, wherein at least about 2 wt.% is the fibrous substrate comprising cellulose. The initial solids content may be at least about 10 wt%, or at least about 20 wt%, or at least about 30 wt%, or at least about 40 wt%. At least about 5 wt% of the initial solids content may be a fibrous substrate comprising cellulose, e.g., at least about 10 wt%, or at least about 15 wt%, or at least about 20 wt% of the initial solids content may be a fibrous substrate comprising cellulose.

In another embodiment, milling is performed in a cascade of milling vessels, one or more of which may include one or more milling zones. For example, the fibrous substrate comprising cellulose and the inorganic particulate material may be milled in a cascade of two or more milling vessels, such as a cascade of three or more milling vessels, or a cascade of four or more milling vessels, or a cascade of five or more milling vessels, or a cascade of six or more milling vessels, or a cascade of seven or more milling vessels, or a cascade of eight or more milling vessels, or a cascade of nine or more milling vessels in series, or a cascade of up to ten milling vessels. The cascade of milling vessels may be operably connected in series or parallel or a combination of series and parallel. The output and/or input of one or more milling vessels in the cascade may be subjected to one or more screening steps and/or one or more classification steps.

The total energy consumed in the microfibrillation process may be equally distributed in each grinding vessel in the cascade. Alternatively, the energy input may vary between some or all of the milling vessels in the cascade.

Those skilled in the art will appreciate that the energy consumed by each vessel may vary from vessel to vessel in the cascade, depending on the amount of fibrous substrate being microfibrillated in each vessel, and optionally the grinding speed in each vessel, the duration of grinding in each vessel, the type of grinding media in each vessel, and the type and amount of inorganic particulate material. The milling conditions can be varied in each vessel of the cascade in order to control the particle size distribution of both microfibrillated cellulose and inorganic particulate material. For example, the size of the milling media may be varied between successive vessels in the cascade in order to reduce milling of the inorganic particulate material and to target milling of the cellulosic containing fibrous substrate.

In one embodiment, the milling is performed in a closed circuit. In another embodiment, milling is performed in an open circuit. The milling may be performed in batch mode. Grinding may be performed in a recycle batch mode. In another embodiment, the milling may be performed in a continuous mode, as described elsewhere in this specification.

As described above, the milling circuit may include a pre-milling step wherein coarse inorganic particles are milled in a milling vessel to a predetermined particle size distribution, after which the cellulosic containing fibrous material is combined with the pre-milled inorganic particulate material and milling is continued in the same or a different milling vessel until the desired level of microfibrillation is obtained.

Since the suspension of the material to be ground may have a relatively high viscosity, it may be preferable to add a suitable dispersant to the suspension prior to grinding. The dispersant may be, for example, a water-soluble condensed phosphate, polysilicic acid or a salt thereof, or a polyelectrolyte, such as a water-soluble salt of poly (acrylic acid) or poly (methacrylic acid) having a number average molecular weight of no greater than 80,000. The amount of dispersant used will typically be in the range of 0.1 to 2.0 wt% based on the dry weight of the inorganic particulate solid material. The suspension may be suitably milled at a temperature in the range 4 ℃ to 100 ℃.

Other additives that may be included during the microfibrillation step include: carboxymethyl cellulose, amphoteric carboxymethyl cellulose, oxidizing agents, 2, 6-tetramethylpiperidin-1-oxyl (TEMPO), TEMPO derivatives and wood degrading enzymes.

The pH of the suspension of the material to be abraded may be about 7 or greater (i.e., alkaline), for example the pH of the suspension may be about 8, or about 9, or about 10, or about 11. The pH of the suspension of the material to be abraded may be less than about 7 (i.e., acidic), for example, the pH of the suspension may be about 6, or about 5, or about 4, or about 3. The pH of the suspension of the material to be ground can be adjusted by adding an appropriate amount of acid or base. Suitable bases include alkali metal hydroxides such as, for example, naOH. Other suitable bases are sodium carbonate and ammonia. Suitable acids include mineral acids such as hydrochloric acid and sulfuric acid, or organic acids. An exemplary acid is orthophosphoric acid.

The amount of inorganic particulate material and cellulose pulp in the mixture to be co-milled may vary at a ratio of about 99.5:0.5 to about 0.5:99.5 based on the dry weight of the inorganic particulate material and the amount of dry fibers in the pulp, for example, at a ratio of about 99.5:0.5 to about 50:50 based on the dry weight of the inorganic particulate material and the amount of dry fibers in the pulp. For example, the ratio of the amount of inorganic particulate material to the dry fiber may be from about 99.5:0.5 to about 70:30. In one embodiment, the ratio of inorganic particulate material to dry fiber is about 80:20, or for example about 85:15, or about 90:10, or about 91:9, or about 92:8, or about 93:7, or about 94:6, or about 95:5, or about 96:4, or about 97:3, or about 98:2, or about 99:1. In a preferred embodiment, the weight ratio of inorganic particulate material to dry fiber is about 95:5. In another preferred embodiment, the weight ratio of inorganic particulate material to dry fiber is about 90:10. In another preferred embodiment, the weight ratio of inorganic particulate material to dry fiber is about 85:15. In another preferred embodiment, the weight ratio of inorganic particulate material to dry fiber is about 80:20.

The total energy input to achieve the desired aqueous suspension composition during typical milling may generally be between about 100 and 1500kwh t, based on the total dry weight of inorganic particulate filler ^-1 Between them. The total energy input may be less than about 1000kWht ^-1 For example less than about 800kWht ^-1 Less than about 600kWht ^-1 Less than about 500kWht ^-1 Less than about kWht ^-1 Less than about 300kWht ^-1 Or less than about 200kWht ^-1 . Thus, the inventors have surprisingly found that when co-grinding cellulose pulp in the presence of inorganic particulate material, the cellulose pulp can be microfibrillated at relatively low energy input. It will be apparent that the total energy input per ton of dry fibers in the cellulosic containing fibrous substrate will be less than about 10,000kwht ^-1 For example less than about 9000kWht ^-1 Or less than about 8000kWht ^-1 Or less than about7000kWht ^-1 Or less than about 6000kWht ^-1 Or less than about 5000kWht ^-1 For example less than about 4000kWht ^-1 Less than about 3000kWht ^-1 Less than about 2000kWht ^-1 Less than about 1500kWht ^-1 Less than about 1200kWht ^-1 Less than about 1000kWht ^-1 Or less than about 800kWht ^-1 . The total energy input varies depending on the amount of dry fibers in the fibrous substrate being microfibrillated and the optional grinding speed and grinding duration.

In another embodiment, the grinding media comprises particles having an average diameter of about 3mm and a specific gravity of about 2.7.

In another embodiment, MFC is manufactured according to the method described in WO-A-2010/131016, the method comprising the step of microfibrillating A fibrous substrate comprising cellulose by grinding in the presence of A particulate grinding medium, which is removed after the grinding is completed. "microfibrillating" means a process in which microfibrils of cellulose are released or partially released as individual substances or as small aggregates, as compared to the fibers of a pre-fibrillated pulp. Typical cellulosic fibers suitable for use in papermaking (i.e., pre-fibrillated pulp) include large aggregates of hundreds or thousands of individual cellulosic fibers. By microfibrillating cellulose, MFC and compositions comprising MFC are given specific features and characteristics, including those described herein.

The cellulosic-containing fibrous substrate (variously referred to herein as "cellulosic-containing fibrous substrate", "cellulosic fibers", "fibrous cellulosic feedstock", "cellulosic feedstock", and "cellulose-containing fibers (or fibrous, etc.) may be derived from recycled pulp or paper mill broke and/or industrial waste, or a paper stream from a paper mill that is rich in mineral fillers and cellulosic materials.

Cellulose pulp may be pulped (e.g., in a Valley beater) and/or otherwise refined (e.g., processed in a cone or plate refiner) to any predetermined freeness, reported in the art as Canadian Standard Freeness (CSF), in cm ³ . CSF means pulp as measured by the rate at which a pulp suspension can drainFreeness or drainage rate, and this test is performed according to the T227cm-09TAPPI standard. For example, the cellulose pulp may have about 10cm before being microfibrillated ³ Or higher Canadian standard freeness. The cellulose pulp may have the following CSF: about 700cm ³ Or lower, e.g., equal to or less than about 650cm ³ Or equal to or less than about 600cm ³ Or equal to or less than about 550cm ³ Or equal to or less than about 500cm ³ Or equal to or less than about 450cm ³ Or equal to or less than about 400cm ³ Or equal to or less than about 350cm ³ Or equal to or less than about 300cm ³ Or equal to or less than about 250cm ³ Or equal to or less than about 200cm ³ Or equal to or less than about 150cm ³ Or equal to or less than about 100cm ³ Or equal to or less than about 50cm ³ . The cellulose pulp may have a CSF of about 20 to about 700. The cellulose pulp may then be dewatered by methods well known in the art, for example, the pulp may be filtered through a screen to obtain a wet sheet comprising at least about 10% solids, for example at least about 15% solids, or at least about 20% solids, or at least about 30% solids, or at least about 40% solids, or at least 50% solids. The pulp may be utilized in an unrefined state, that is, without being pulped or dewatered, or otherwise refined.

In another embodiment, microfibrillated cellulose is prepared according to a process comprising the steps of: microfibrillating a fibrous substrate comprising cellulose by milling in an aqueous environment in the presence of a milling medium, which is removed after milling is completed, wherein milling is performed in a tower mill or a screen mill, and wherein milling is performed in the absence of a millable inorganic particulate material.

The abradable inorganic particulate material is a material to be abraded in the presence of an abrasive medium.

The particulate grinding media may be a natural or synthetic material. The grinding media may, for example, comprise spheres, beads or pills of any hard mineral, ceramic or metallic material. Such materials may include, for example, alumina, zirconia, zirconium silicate, aluminum silicate, or byMullite-rich materials produced by calcining kaolinite clay at a temperature in the range of about 1300 ℃ to about 1800 ℃. For example, in some embodiments, the first and second substrates,

grinding media are preferred. Alternatively, natural sand particles having a suitable particle size may be used.

In general, the type and particle size of the grinding media to be selected for use in the present invention may depend on the characteristics, such as, for example, the particle size and chemical composition of the feed suspension of the material to be ground. Preferably, the particulate grinding media comprises particles having an average diameter in the range of about 0.5mm to about 6 mm. In one embodiment, the particles have an average diameter of at least about 3 mm.

The grinding media may comprise particles having a specific gravity of at least about 2.5. The grinding media may comprise particles having a specific gravity of at least about 3, or at least about 4, or at least about 5, or at least about 6.

The grinding medium (or media) may be present in an amount up to about 70% by volume of the loaded material. The milling media may be present in an amount of at least about 10% by volume of the loaded material, such as at least about 20% by volume of the loaded material, or at least about 30% by volume of the loaded material, or at least about 40% by volume of the loaded material, or at least about 50% by volume of the loaded material, or at least about 60% by volume of the loaded material.

The fibrous substrate comprising cellulose may be fibrillated to obtain a fiber having a d ranging from about 5 μm to about 500 μm as measured by laser light scattering ₅₀ Is used for the microfibrillated cellulose. The fibrous substrate comprising cellulose may be microfibrillated to obtain a fibrous substrate having the following d ₅₀ Is a microfibrillated cellulose of (a): about 400 μm or less, for example about 300 μm or less, about 200 μm or less, about 150 μm or less, about 125 μm or less, about 100 μm or less, about 90 μm or less, about 80 μm or less, about 70 μm or less, about 60 μm or less, about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, or less Or less than about 10 μm.

The fibrous substrate comprising cellulose may be microfibrillated to obtain microfibrillated cellulose having a modal fiber particle size in the range of about 0.1-500 μm. The fibrous substrate comprising cellulose may be microfibrillated in the presence of inorganic particulate material to obtain microfibrillated cellulose having the following modal fiber particle size: at least about 0.5 μm, such as at least about 10 μm, or at least about 50 μm, or at least about 100 μm, or at least about 150 μm, or at least about 200 μm, or at least about 300 μm, or at least about 400 μm.

The fibrous substrate comprising cellulose may be microfibrillated to obtain microfibrillated cellulose having a fiber steepness as measured by Malvern of equal to or greater than about 10. The fiber steepness (i.e., steepness of the fiber particle size distribution) is determined by the following formula:

steepness=100× (d _3o /d _7o )。

Microfibrillated cellulose may have a fiber steepness equal to or less than about 100. The microfibrillated cellulose may have a fiber steepness of equal to or less than about 75, or equal to or less than about 50, or equal to or less than about 40, or equal to or less than about 30. The microfibrillated cellulose may have a fiber steepness of about 20 to about 50, or about 25 to about 40, or about 25 to about 35, or about 30 to about 40. In one embodiment, the preferred steepness range is about 20 to about 50.

Calculation of fiber steepness for MFC fibers and inorganic particulate materials is well known in the art. For example, a sample of co-ground slurry sufficient to produce 5g dry matter is weighed into a beaker, diluted to 60g with deionized water, and mixed with 5cm ³ Is mixed with a solution of 1.0 wt.% sodium carbonate and 0.5 wt.% sodium hexametaphosphate. Deionized water was further added with stirring to achieve a final slurry weight of 80 g. Then, 1cm is used ³ Aliquots of the slurry were added to the water in the sample preparation device attached to a Mastersizer S (or Mastersizer Insitec or other similar device) until an optimal level of shading (typically 10% -15%) was exhibited. Then, a light scattering analysis program was performed. The instrument range selected was 300RF:0.05-900 and the beam length is set to 2.4mm. For co-ground samples containing calcium carbonate and fibers, calcium carbonate was usedRefractive index (1.596). For the co-ground sample of kaolin and fiber, RI of kaolin (1.5295) was used. The particle size distribution was calculated from Mie theory and the output was given as a distribution based on different volumes. The presence of two distinct peaks is interpreted as coming from minerals (finer peaks) and fibers (coarser peaks).

The finer mineral peaks are fitted to the measured data points and subtracted mathematically from the distribution to leave fiber peaks, which are converted to cumulative distributions. Similarly, mathematically subtracting the fiber peak from the original distribution to leave a mineral peak also converts the mineral peak to a cumulative distribution. These two cumulative curves can then be used to calculate the average particle size (d ₅₀ ) And steepness of distribution (d ₃₀ /d ₇₀ X 100). The differential curve can be used to find the modal particle size of both the mineral fraction and the fiber fraction.

The tower mill may include a screen above one or more grinding zones. In one embodiment, the screen is located near the quiescent zone and/or classifier. The screen may be sized to separate the grinding media from the aqueous suspension of the product comprising microfibrillated cellulose and enhance settling of the grinding media.

In one embodiment, water is added at the top of the mill near the stationary zone or classifier or screen above the one or more milling zones to reduce the viscosity of the aqueous suspension comprising microfibrillated cellulose in these zones in the mill. It has been found that by diluting the product microfibrillated cellulose at this point in the mill, the prevention of carrying of the grinding media to the rest area and/or classifier and/or screen is improved. In addition, limited mixing through the column allows for treatment at the lower portion of the column at higher solids and dilution at the top, with limited reflux of dilution water to the lower portion of the column into one or more grinding zones. Any suitable amount of water effective to dilute the viscosity of the aqueous suspension of the product comprising microfibrillated cellulose may be added. The water may be added continuously during the milling process, or periodically, or aperiodically.

In another embodiment, the milling is performed in a screening mill (preferably a stirred media chipper). The screening mill may include one or more screens having a nominal pore size of at least about 250 μm, for example, the one or more screens may have a nominal pore size of at least about 300 μm, or at least about 350 μm, or at least about 400 μm, or at least about 450 μm, or at least about 500 μm, or at least about 550 μm, or at least about 600 μm, or at least about 650 μm, or at least about 700 μm, or at least about 750 μm, or at least about 800 μm, or at least about 850 μm, or at least about 900 μm, or at least about 1000 μm, or at least about 1,250 μm, or at least about 1,500 μm.

As described above, the grinding is performed in the presence of a grinding medium. In one embodiment, the grinding media is a coarse media comprising particles having an average diameter in the range of about 1mm to about 6mm, such as about 2mm, or about 3mm, or about 4mm, or about 5 mm.

As noted above, the amount of grinding media (or media) may be up to about 70% by volume of the load material. The milling media may be present in an amount of at least about 10% by volume of the loaded material, such as at least about 20% by volume of the loaded material, or at least about 30% by volume of the loaded material, or at least about 40% by volume of the loaded material, or at least about 50% by volume of the loaded material, or at least about 60% by volume of the loaded material.

By "load" is meant the composition added as feed to the mill vessel. The load material includes water, grinding media, cellulosic-containing fibrous substrates, and any other optional additives (except as described herein).

The use of relatively coarse and/or dense media has the advantage of increasing (i.e., faster) deposition rates and reducing media carryover through the quiescent zone and/or classifier and/or screen(s).

According to one embodiment, the fibrous substrate comprising cellulose is present in an aqueous environment at an initial solids content of at least about 1% by weight. The fibrous substrate comprising cellulose may be present in the aqueous environment at an initial solids content of at least about 2 wt%, such as at least about 3 wt% or at least about 4 wt%. Typically, the initial solids content will not exceed about 10 weight percent.

In another embodiment, milling is performed in a cascade of milling vessels, one or more of which may include one or more milling zones. For example, a fibrous substrate comprising cellulose may be milled in a cascade of two or more milling vessels, such as a cascade of three or more milling vessels, or a cascade of four or more milling vessels, or a cascade of five or more milling vessels, or a cascade of six or more milling vessels, or a cascade of seven or more milling vessels, or a cascade of eight or more milling vessels, or a cascade of nine or more milling vessels in series, or a cascade of up to ten milling vessels. The cascade of milling vessels may be operably connected in series or parallel or a combination of series and parallel. The output and/or input of one or more milling vessels in the cascade may be subjected to one or more screening steps and/or one or more classification steps.

Those skilled in the art will appreciate that the energy consumed by each vessel may vary from vessel to vessel in the cascade, depending on the amount of fibrous substrate being microfibrillated in each vessel, and optionally the grinding speed in each vessel, the duration of grinding in each vessel, and the type of grinding media in each vessel. The milling conditions may be changed in each vessel of the cascade so as to control the particle size distribution of the microfibrillated cellulose.

In one embodiment, the milling is performed in a closed circuit. In another embodiment, milling is performed in an open circuit.

The pH of the suspension of the material to be abraded may be about 7 or greater (i.e., alkaline), for example the pH of the suspension may be about 8, or about 9, or about 10, or about 11. The pH of the suspension of the material to be abraded may be less than about 7 (i.e., acidic), for example the pH of the suspension may be about 6, or about 5, or about 4, or about 3. The pH of the suspension of the material to be ground can be adjusted by adding an appropriate amount of acid or base. Suitable bases include alkali metal hydroxides such as, for example, naOH. Other suitable bases are sodium carbonate and ammonia. Suitable acids include mineral acids, such as hydrochloric acid and sulfuric acid, or organic acids. An exemplary acid is orthophosphoric acid.

The total energy input to achieve the desired aqueous suspension composition during typical milling may generally be between about 100 and 1500kwh t, based on the total dry weight of inorganic particulate filler ¹ Between them. Total energy inputCan be less than about 1000kWht ^-1 For example less than about 800kWht ^-1 Less than about 600kWht ^-1 Less than about 500kWht ^-1 Less than about 400kWht ^-1 Less than about 300kWht ^-1 Or less than about 200kWht ^-1 . Thus, the inventors have surprisingly found that when co-grinding cellulose pulp in the presence of inorganic particulate material, the cellulose pulp can be microfibrillated at relatively low energy input. It will be apparent that the total energy input per ton of dry fibers in the cellulosic containing fibrous substrate will be less than about 10,000kwht ^-1 For example less than about 9000kWht ^-1 Or less than about 8000kWht ^-1 Or less than about 7000kWht ^-1 Or less than about 6000kWht ^-1 Or less than about 5000kWht ^-1 For example less than about 4000kWht ^-1 Less than about 3000kWht ^-1 Less than about 2,000kWht ^-1 Less than about 1500kWht ^-1 Less than about 1200kWht ^-1 Less than about 1000kWht ^-1 Or less than about 800kWht ^-1 . The total energy input varies depending on the amount of dry fibers in the fibrous substrate being microfibrillated and the optional grinding speed and grinding duration.

Various aspects of the invention are described in more detail in the following sections. The use of segmentation is not meant to limit the invention. Each segment may be applied to any aspect of the present invention. In this application, unless otherwise stated, the use of "or" means "and/or".

MFC can be produced in continuous or batch mode. MFC is an aqueous suspension mixture of microfibrillated cellulose and inorganic particulate material. In one embodiment, MFC is prepared by co-milling a low solids aqueous suspension of cellulose wood pulp in the presence of particles of an inorganic particulate material in a wet vertical stirred media mill. The mineral particles act as grinding aids and promote cost-effective fibrillation of pulp fibers into microfibers in a process similar to pulp refining.

The inorganic particulate material used is standard paper filler, typically calcium carbonate or kaolin. Most processes will use kaolin, ground calcium carbonate or precipitated calcium carbonate. The inorganic particulate material will be in the form of an aqueous slurry.

The cellulose used is typically unrefined kraft or sulfite pulp (> 99% cellulose) from a paper mill pulp source or recycled pulp from paper and board recycling activities. Pulp received from paper mills is typically an aqueous slurry of about 4-5% solids by weight. The water used is from a process stream from a factory or, in some cases, from municipal (urban) water service. The ceramic grinding media is typically 3mm diameter beads made from calcined kaolin. In some cases, when recycled pulp is used, the pulp already contains some inorganic particulate material.

In an illustrative formulation: about 4% solids kraft pulp and about 66% solids hydrous kaolin clay or about 75% solids calcium carbonate slurry and water are continuously added to the mill. The mill was charged with mullite grinding media having a diameter of 3mm such that approximately 50% of the total load volume was occupied by the media (total load volume = volume occupied by mullite + pulp + kaolin + water). The yield is controlled such that the pulp and mineral mixture is co-ground for an optimized period of time. Typically, this optimization period corresponds to the development of maximum viscosity and tensile properties. Typically, about 1500-5000 kWhr/dry ton MFC is applied. During the milling process, the temperature in the mill reached about 65 degrees celsius. MFC product was in the form of an aqueous slurry.

In some cases, the same process is operated batchwise, rather than continuously. In this case, the ingredients were added at the start of the batch, then the mill was run for a specified time such that 1500-5000 kWhr/dry ton MFC was applied, and then further water was added at the end of the batch, and the product was discharged before repeating the process.

In some cases, when the inorganic particulate material is not acceptable in the end use application, then the process described above is performed without any addition of inorganic particulate material.

The MFC products produced by the milling and sieving process described above contain agglomerates that reduce performance and, if very fine sieving is performed, the agglomerates may cause clogging. These agglomerates can be reduced by using a homogenizer.

In some cases, some of the water associated with the MFC product is removed to reduce transportation costs. This is achieved by using dewatering via a belt press and/or drying using a hot air dryer or by other means known in the art. When preparing dehydrated and dried products, biocides are sometimes added to extend shelf life and prevent product degradation. For example, biocides are mixed into MFC using a plow shear mixer. The dehydrated and partially dried product is typically transported in bulk bags.

The biocides used were DBNPA (2, 2-dibromo-3-nitrilopropionamide), and CMIT/MIT (5-chloro-2-methyl-2H-isothiazol-3-one/2-methyl-2 Hi-isothiazol-3-one (CMIT/MIT), or for partially dried products and OIT (2-octyl-2H-isothiazol-3-one).

A continuous production process is a pass-through process in which cellulose, inorganic particulate material and water come from a plant and are returned to the plant after treatment.

Parameters that can be used to control the production are the product d as measured by laser light scattering ₅₀ As well as viscosity or tensile properties, such as FLT tensile index, as described elsewhere herein.

Microporous inorganic particulate material composite

Other examples of microporous inorganic particulate materials include chemically aggregated filler materials. Examples of such chemically aggregated fillers can be found in U.S. patent No. 4,072,537, which is incorporated herein in its entirety. Such microporous inorganic particulate materials comprise a composite silicate material comprising a clay component and a metal silicate component. The clay component is typically kaolin or kaolinite, and the metal silicate material is typically a water-soluble alkali metal silicate, such as sodium silicate.

All of the foregoing materials are composed of particles that contain rigid internal void spaces that persist during the paper pressing and drying process and should remain substantially intact after calendering.

Scalenohedral PCC, calcined clay and chemically aggregated fillers achieve this structure by forming open aggregates of smaller particles and firmly bonding the particles where they contact each other. Diatomaceous earth consists of particles that naturally contain pores. The ground expanded perlite consists of micron-sized glass bubble fragments. Thus, microporous inorganic particulate materials comprise discrete particles or aggregates of particles having an external dimension of a few microns, which contain void spaces within the volume defined by the external dimension, and which are several times smaller than the external dimension. In general, for the purposes of the present invention, the foregoing inorganic particulate materials are referred to herein as "microporous inorganic particulate materials".

When used in paper, these microporous inorganic particulate materials have a much greater impact on fiber spacing than solid filler particles for each unit mass of filler. This makes them more detrimental to the paper strength but produces increased light scattering, which is beneficial for the optical properties.

In one aspect of the present disclosure, the microporous inorganic particulate material composite has a median particle size (d) of less than about 10 μm and greater than about 3 μm, or from about 3 μm to about 6 μm ₅₀ )。

In one aspect of the disclosure, the microporous inorganic particulate material composite, d of the microporous mineral composite ₅₀ D of unagglomerated mixture of the same components as used to form the microporous mineral composite ₅₀ Significantly larger than the previous.

The microporous inorganic particulate material and microfibrillated cellulose composite may be provided in powder form, but they are preferably added in suspension (such as an aqueous suspension). In this case the solids content of the suspension is not critical as long as it is a pumpable liquid.

For a weight median particle size d ₅₀ For d ₅₀ Particles larger than 0.5 μm may be used with the Sedigraph 5100 device from Micromeritics, inc. Can be 0.1 wt% of Na ₄ P ₂ O ₇ Is measured in aqueous solution. A high speed stirrer and ultrasonic dispersion of the sample may be used. For d ₅₀ The volume median particle size of the particles of < 500nm can be determined using Malvern Mastersizer from Malvern, UK. Can be 0.1 wt% of Na ₄ P ₂ O ₇ Is measured in aqueous solution. A high speed stirrer and ultrasonic dispersion of the sample may be used. Sedigraph 5100 provides a measured value and cumulative weight percentage curve for particles having a size known in the art as "equivalent spherical diameter" or "esd". Alternatively, the particle size characteristics of the microporous mineral composite may be measured by Malvern Mastersizer or Microtrac laser particle size distribution analyzer using the instructions of the supplier.

In one aspect of the disclosure, the weight ratio of the first inorganic particulate material to the second inorganic particulate material may range from about 10:90 to about 90:10, such as from about 20:80 to about 80:20, from about 25:75 to 75:25, from about 40:60 to about 60:40, or about 50:50.

Adhesive agent

In one aspect of the disclosure, a binder may be used to promote agglomeration of the second microporous inorganic particulate material onto the first microporous inorganic particulate material and/or microfibrillated cellulose. For example, in some embodiments, the binder may be an alkaline silica binder.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the binder may include at least one of an inorganic binder or an organic binder. The binder may also improve adhesion and mechanical strength between the microporous mineral composite components.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the binder may include an inorganic binder, such as an alkali metal silicate.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the blend of inorganic particulate materials may be contacted with the binder solution by mixing the binder solution with the blend of inorganic particulate materials.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the mixing may include stirring.

In one embodiment of the foregoing aspect and embodiment of the present disclosure, the blend of the first and second microporous inorganic particulate materials and the binder solution is thoroughly mixed to at least substantially uniformly distribute the binder solution among the contact agglomeration points of the first and/or the first and second inorganic particulate materials.

In one embodiment of the foregoing aspect and embodiment of the present disclosure, the blend of first and second microporous inorganic particulate materials and the binder solution may be mixed with sufficient agitation to at least substantially uniformly distribute the binder solution among contact agglomeration points of the blend of first and second inorganic particulate materials without disrupting the structure of the first or second inorganic particulate materials.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the contacting may comprise low shear mixing.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the mixing may be performed at about room temperature (i.e., about 20 ℃ to about 23 ℃). In other embodiments, the mixing may be performed at a temperature ranging from about 20 ℃ to about 50 ℃. In further embodiments, the mixing may be performed at a temperature ranging from about 30 ℃ to about 45 ℃. In other embodiments, the mixing may be performed at a temperature of about 35 ℃ to about 40 ℃.

In one embodiment of the foregoing aspect and embodiment of the present disclosure, the contacting may include spraying the blend of the first and/or the first and the second microporous inorganic particulate materials with a binder solution. In some embodiments, the spraying may be intermittent. In other embodiments, the spraying may be continuous. In a further embodiment, spraying comprises mixing a blend of the first and second microporous inorganic particulate materials while spraying the binder solution, e.g., to expose different contact agglomeration points to the spray. In some embodiments, such mixing may be intermittent. In other embodiments, this mixing may be continuous.

In one embodiment of the foregoing aspects and embodiments of the present disclosure, the binder may be present in the binder solution in an amount of less than about 40% by weight relative to the weight of the binder solution. In some embodiments, the binder may range from about 1 wt% to about 10 wt%. In further embodiments, the binder may range from about 1 wt% to about 5 wt%.

In one embodiment of the foregoing aspect and embodiment of the present disclosure, the binder promotes agglomeration of the second microporous inorganic particulate material onto the first microporous inorganic particulate material. According to some embodiments, the second microporous inorganic particulate material has a smaller diameter than the first microporous inorganic particulate material.

In one aspect of the disclosure, the microporous inorganic particulate material and microfibrillated cellulose composite may be combined with a dispersant, such as those selected from the group comprising: homopolymers or copolymers of polycarboxylic acids and/or salts or derivatives thereof, such as esters based on, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid; for example, acrylamide or an acrylate, such as methyl methacrylate, or mixtures thereof; alkaline polyphosphates, phosphonic, citric and tartaric acids and salts or esters thereof; or a mixture thereof.

In one aspect of the present disclosure, the combination of microfibrillated cellulose and microporous inorganic particulate material may be performed by adding microporous inorganic particulate material to the MFC in one or several steps.

In one aspect of the present disclosure, a combination of microporous inorganic particulate materials may be added to the MFC in one or several steps. Microfibrillated cellulose and microporous inorganic particulate material may be added in whole or in part after the fibrillation step.

In one aspect of the disclosure, the weight ratio of MFC to microporous inorganic particulate material on a dry weight basis is from 1:33 to 10:1, more preferably from 1:10 to 7:1, even more preferably from 1:5 to 5:1, typically from 1:3 to 3:1, especially from 1:2 to 2:1 and most preferably from 1:1.5 to 1.5:1, for example 1:1.

In one aspect of the present disclosure, the total content of microporous inorganic particulate material is present in an amount of 10 to 95 wt%, preferably 15 to 90 wt%, more preferably 20 to 75 wt%, even more preferably 25 to 67 wt%, especially 33 to 50 wt%, based on the dry weight of the composite material.

Precipitated calcium carbonate

Precipitated Calcium Carbonate (PCC) may be used as a source of particulate calcium carbonate in the present invention and may be produced by any method known in the art. TAPPI Monograph Series No30,' Paper Coating Pigments ", pages 34-35 describe three main commercial processes for the preparation of precipitated calcium carbonate which is suitable for use in the preparation of products for the paper industry, but which can also be used in the practice of the present invention. In all three processes, a calcium carbonate feed (such as limestone) is first calcined to produce quicklime, which is then slaked in water to produce calcium hydroxide or milk of lime. In the first process, milk of lime is directly carbonated with carbon dioxide gas. The advantage of this process is that no by-products are formed and the properties and purity of the calcium carbonate product are relatively easy to control. In the second process, milk of lime is contacted with soda to produce calcium carbonate precipitate and sodium hydroxide solution by metathesis. If the process is used commercially, the sodium hydroxide may be substantially completely separated from the calcium carbonate. In the third main commercial process, milk of lime is first contacted with ammonium chloride to obtain a calcium chloride solution and ammonia gas. The calcium chloride solution is then contacted with soda ash to produce calcium carbonate precipitate and sodium chloride solution by metathesis. The crystals may be produced in a variety of different shapes and sizes depending on the particular reaction process used. Three major forms of PCC crystals are aragonite, rhombohedral and scalenohedral, all of which (including mixtures thereof) are suitable for use in the present invention.

In certain embodiments, PCC may be formed during the production of microfibrillated cellulose.

Wet milling of calcium carbonate involves forming an aqueous suspension of calcium carbonate, which may then optionally be milled in the presence of a suitable dispersant. Reference may be made to, for example, EP-a-614948 (the contents of which are incorporated herein by reference in their entirety) for more information about wet grinding of calcium carbonate.

In some cases, other minerals may be included in small additions, for example, one or more of kaolin, calcined kaolin, wollastonite, bauxite, talc, or mica may also be present.

Examples

Example 1. Coarse scalenohedral PCC and FiberLean MFC were used to maintain bulk and stiffness as the filler content was increased.

The furnish is made up of 70% hardwood (eucalyptus, e.g., UPMUruguay) and 30% softwood (BOTNIARMA 90 pine, e.g., stump) co-refined to 450CSF (28.5 ° s.r.)

) Is prepared.

The study was designed at 80g/m ² UWF paper is targeted, which is derived from GCC (60%<2 μm) was added at a starting filler content of 19%.

The MFC product used was a 50% POP MFC slurry consisting of NBSK Botnia RMA90 and GCC minerals (60% <2 μm).

The retention aid was added at 0.12% based on dry sheet weight. The retention aid is a cationic polyacrylamide (Percol 292NS, e.g., BASF). The white water was recycled during sheet formation (as the white water from each sheet was used to form subsequent sheets in the series of test points to ensure that each formulation reached equilibrium of retention). Further details regarding sheet forming methods are shown in the appendix.

The results of example 1 are summarized in table 1.

Table 1: summary of results when PCC and MFC were used to recover bulk and stiffness at increased filler content.

Note that: the furnish (70% eucalyptus/30% pine) represents 100% pulp furnish, which is then replaced by the ratio shown by filler and MFC, depending on the total mass of each sheet.

These results indicate that:

increasing the filler content from 20% to 30% using standard GCC (IC 60, median size 1.6 μm) and 3% mfc resulted in a slight decrease in strength but significant loss of bulk and stiffness.

Increasing MFC dose will result in greater bulk losses.

Increasing the filler content from 20% to 30% using coarse PCC (median size 3.1 μm) resulted in very high porosity and low strength.

The combination of 30% pcc and 4% mfc resulted in high bulk, acceptable porosity and strength, and stiffness comparable to 20% gcc filled paper.

In summary, the examples show that:

the addition of MFC improves mechanical properties, opacity, porosity and roughness. As an exchange for these improvements, several possibilities are provided:

and (3) batching adjustment: decreasing long fiber or increasing CTMP content (proportionally adjusting short fiber content).

The type of filler used is changed and the filler content is increased.

Both possibilities make it possible to save costs.

The use of MFC also reduces bulk, which in turn leads to a compromise in stiffness. Furthermore, the use of MFC to increase filler levels may result in greater damage to stiffness.

These bulk/stiffness losses can be counteracted by:

switching to coarser/larger packing.

Reducing the content of long fibers in the ingredients.

The mechanical pulp content in the furnish is increased.

These different levels of optimization can maximize cost savings and overall paper characteristics when MFCs are used.

All paper tests were performed according to the following TAPPI standard:

internal bond strength (scott bond): t569

Tensile properties: t494

Bendtsen porosity: t460

Thickness (caliper for calculation of bulk): t411

Basis weight: t410

Opacity: t425

Ash content: t413 and T211

Tensile strength of

Burst strength: t403

Tear strength

Tensile Strength in the "Z" direction (perpendicular to the plane of the paper)

Flexural rigidity: t535

Bulk or thickness.

Roughness: t555.

Sheet preparation

According to TAPPI standard T205, in Rapid

All handsheets were prepared on a sheet former. To ensure that the total retention of all components of the furnish used to prepare the sheet is very high, the white water is recycled after each sheet is formed and used to dilute the furnish used to prepare the next sheet. The first 5 sheets of each composition were discarded to allow the material not retained in the circulating water to accumulate to a steady state, after which 7 additional sheets were formed, pressed and dried for testing. In all cases, the target packing loading was achieved within 2 percentage points. Cationic retention aid (Percol 292ns, basf) was added to each furnish at a level of 0.12% based on total solids in the furnish. Paper properties were measured according to the relevant TAPPI standard. The filler content was calculated from the residual ash weight measured after the sheet was placed in a furnace at 450 ℃ for 2 hours. At this temperature, the calcium carbonate filler used was not lost on ignition.

Example 2

Handsheets were made from a blend of bleached kraft pulp comprising 70% hardwood (eucalyptus, UPM uguay) and 30% softwood (pine, meta Botnia RMA 90). These were co-refined in a laboratory Valley beater to a freeness of 450ml CSF (28.5 ° s.r.). Each sheet was made to 80gsm of target material with a target filler content of 20 wt.% or 30 wt.%.

MFC was produced by co-milling Botnia RMA90 bleached kraft pine pulp with standard filler grade ground calcium carbonate (GCC, intracarb60, 60% <2 μm by weight, d50 1.4 μm, imarys) at a 50/50 weight ratio using a stirred media chipper mill.

GCC (Intracab 60) or scalenohedral PCC (Syncarb S350, omya,3.5 mu m d) ₅₀ ) To the furnish of each sheet such that its total filler content (including the filler added with co-grinding MFC) will match the target value of the final sheet.

The paper properties of the formed handsheet were found to be in error-! The reference source is not found. Showing the same.

TABLE 2

/>

Table 3 below and fig. 1 show the relative change in key properties of each composition compared to a reference sheet filled with 20% GCC. Increasing the filler content to 30% with GCC resulted in a significant loss of mechanical properties, which could be partially recovered by adding 3% MFC. The conversion from GCC to coarse PCC at 20% load resulted in a significant increase in bulk and stiffness, but at the cost of tensile index and scott bond, and further increasing to 30% PCC reduced the latter to a level below GCC while also reducing stiffness below the reference value. The addition of 4% MFC restored the stiffness to within 5% of its original value while providing improvements over the reference in terms of bulk, scott bond and light scattering.

TABLE 3 Table 3

Composition and method for producing the same	Relative Scott bond	Relative tensile index	Relative flexural rigidity	Relative stacking volume	Relative light scattering

GCC
	20% mfc free	1.00	1.00	1.00	1.00	1.00
GCC 30% mfc free							0.70	0.73	0.72	1.01	1.15
	GCC 30％3％mfc	0.88	0.94	0.85	0.98	1.19

	PCC 20% mfc free	0.97	0.95	1.35	1.16	1.05
PCC 30% mfc free							0.73	0.72	0.90	1.19	1.20
	PCC 30％4％mfc	1.04	0.86	0.95	1.14	1.25

Example 3

Handsheets were made from a blend of 95% bleached eucalyptus kraft pulp and 5% bleached chemi-thermo-mechanical pulp (BCTMP). Kraft pulp was co-refined in a laboratory Valley beater to a freeness of 330ml CSF (37.5 ° s.r.). Each sheet was made to a target mass of 75gsm with a target filler content of 25 wt% or 35 wt%.

Co-milling bleached eucalyptus kraft with standard filler grade ground calcium carbonate (GCC, hydrocarb 60, 60% by weight) at a 50/50 weight ratio by using a stirred media chipper mill<2μm，d ₅₀ 1.4 μm, omya) to produce MFC.

The reference sheet contains 25% GCC. For all other sheets, 2% MFC was added and GCC (hydro ar b 60) and scalenohedral PCC (3.1 μm d ₅₀ Obtained from a satellite PCC plant of a paper mill) is added to the furnish of each sheet such that its total filler content (including the filler added with the co-milled MFC) is 35% and the proportion of PCC filler in the blend is a fixed value between 0% and 100%.

The paper properties of the formed handsheets are shown in table 4 below.

TABLE 4 Table 4

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The effect of changing from GCC to coarse PCC is in error ≡! The reference source is not found. To error-! The reference source is not found. Showing the same. Error-! The reference source is not found. It was shown that even if 2% of MFC was added, an increase in GCC filler from 25% to 35% resulted in a significant decrease in bending stiffness, but replacing the added GCC with coarse PCC restored the bending stiffness to the reference value. Error-! The reference source is not found. It was shown that replacing GCC with PCC increases the light scattering coefficient of the paper beyond what has been achieved by increasing the filler content. Error-! The reference source is not found. To error-! The reference source is not found. It was shown that in this highly refined formulation, the tensile index and scott bond decreased slightly with increasing filler, although 2% MFC was added, this was not significantly affected by the substitution of PCC for GCC.

Example 4

Handsheets were made from a blend of bleached kraft pulp comprising 70% eucalyptus and 30% pine. These were co-refined in a laboratory Valley beater to a freeness of 350ml CSF (36 ° s.r.). Each sheet was made to 80gsm of target material with a target filler content ranging from 16 wt% to 35 wt%.

Standard filler grade scalenohedral PCC (2.3 mu m d ₅₀ Obtained from satellite PCC factory at paper mill) or coarse-scale scalenohedral PCC (Syncarb S300, omya,3.0 μm d) ₅₀ ) To the furnish of each sheet such that its total filler content (including the filler added with co-grinding MFC) will match the target value of the final sheet.

The paper properties of the formed handsheets are shown in table 5 below.

TABLE 5

Error-! The reference source is not found. It was shown that for a constant tensile index, adding 1% MFC allowed the filler content of standard PCC to increase by 3.5%, but the filler content of coarser PCC to increase by 6%.

Error-! The reference source is not found. Showing an increase of 3.5% for standard 2.3 μm filler and an increase of 100cm in light scattering ² g ^-1 And for a coarse 3.0 μm filler an increase of 6% and an increase of 80cm in light scattering ² g ^-1 。

Error-! The reference source is not found. These increases were shown to produce equal stiffness for the 2.3 μm filler, but for the coarse 3.0 μm filler, resulting in an increase in stiffness of 0.04mN m (7%).

Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. The scope of the invention is not intended to be limited to the above description but is set forth in the following claims.

Use of ordinal terms such as "first," "second," "third," etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (if no ordinal term is used) to distinguish the claim elements.

The article "a" or "an" as used herein in the specification and claims should be understood to include plural referents unless the contrary is explicitly indicated. Unless indicated to the contrary or otherwise apparent from the context, claims or descriptions that include "or" between one or more members of a group are considered satisfied if one, more than one, or all members of the group are present, employed, or otherwise associated with a given product or process. The present invention includes embodiments in which exactly one member of the group is present, employed, or otherwise associated with a given product or process. The invention also includes embodiments in which more than one member or all members of a group are present in, employed in, or otherwise associated with a given product or process. Furthermore, it is to be understood that the invention includes all changes, combinations and permutations of one or more limitations, elements, clauses, descriptive terms, etc. from one or more of the listed claims that are introduced into another claim dependent on the same base claim (or any other claim relevant) unless otherwise indicated or unless contradictory or otherwise apparent to one of ordinary skill in the art. Where elements are presented in a list (e.g., markush group) or similar format, it is to be understood that each subgroup of the elements is also disclosed and any one or more elements may be removed from the group. It should be understood that, in general, when the invention or aspects of the invention are referred to as comprising or consisting essentially of particular elements, features, etc., certain embodiments of the invention or aspects of the invention consist of such elements, features, etc. For the sake of simplicity, these embodiments are not specifically set forth herein in every case in so much of the text. It should also be understood that any embodiment or aspect of the invention may be explicitly excluded from the claims, whether or not a particular exclusion is set forth in the specification. Publications, web sites, and other references cited herein to describe the background of the invention and to provide additional details regarding its practice are hereby incorporated by reference.

Claims

1. A paper or paperboard filler composition comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials and for addition to a papermaking furnish used to make paper or paperboard, wherein the MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to a paper or paperboard product made from the same papermaking furnish without MFC and the one or more microporous inorganic particulate materials.

2. The filler composition of claim 1, wherein the MFC is obtained by a co-grinding microfibrillation process, wherein a fibrous substrate comprising cellulose is microfibrillated in an aqueous environment in a grinding apparatus in the presence of the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material; wherein the ratio of the fibrous substrate to the inorganic particulate material is from about 99.5:0.5 to about 0.5:99.5.

3. The filler composition of claim 1, wherein the one or more microporous inorganic particulate materials comprise calcined clay, kaolin, kaolinite, amorphous aluminum silicate, scalenohedral precipitated calcium carbonate, aragonite precipitated calcium carbonate, chemically aggregated filler material, diatomaceous earth, and ground expanded perlite.

4. The filler composition of claim 1, wherein the microporous inorganic material comprises calcined clay.

5. The filler composition of claim 1, wherein the microporous inorganic material comprises kaolin.

6. The filler composition of claim 1, wherein the microporous inorganic material comprises kaolinite.

7. The filler composition of claim 1, wherein the microporous inorganic material comprises calcined clay.

8. The filler composition of claim 1, wherein the microporous inorganic material comprises amorphous aluminum silicate.

9. The filler composition of claim 1, wherein the microporous inorganic material comprises scalenohedral precipitated calcium carbonate.

10. The filler composition of claim 1, wherein the microporous inorganic particulate material comprises at least two of calcined clay, kaolin, kaolinite, amorphous aluminum silicate, scalenohedral precipitated calcium chloride, aragonite precipitated calcium carbonate, chemically aggregated filler material, diatomaceous earth, ground expanded perlite.

11. The filler composition of any one of claims 1 to 10, wherein the papermaking furnish comprises one or more pulps selected from softwood pulps.

12. The filler composition of claim 11, wherein the softwood pulp is selected from spruce, pine, fir, larch and hemlock or mixed softwood pulp.

13. The filler composition of any one of claims 1 to 10, wherein the papermaking furnish comprises one or more pulps selected from hardwood pulp.

14. The filler composition of claim 13, wherein the hardwood pulp is selected from eucalyptus, aspen, and birch, or mixed hardwood pulp.

15. The filler composition of any one of claims 1 to 10, wherein the pulp source of the papermaking furnish is selected from the group consisting of eucalyptus pulp, spruce pulp, pine pulp, beech pulp, hemp pulp, acacia pulp, cotton pulp, and mixtures thereof.

16. The filler composition of any one of claims 1 to 10, wherein the pulp source of the papermaking furnish is selected from the group consisting of northern european pine, black spruce, radiata pine, southern pine, enzyme treated northern european pine, douglas fir, dissolving pulp, birch, eucalyptus, acacia, mixed european hardwood, mixed thai hardwood, paper towel dust, cotton, abaca, sisal, bagasse, kenaf, miscanthus, sorghum, arundo and flax.

17. The filler composition of any one of claims 1-10, wherein the mechanical property is selected from one or more of tensile strength, tensile elongation, bulk, tensile stiffness, flexural stiffness, porosity, burst and tear strength, and tensile strength in the "Z" direction.

18. The filler composition of claim 17, wherein the mechanical property is tensile strength.

19. The filler composition of claim 17, wherein the mechanical property is tensile elongation.

20. The filler composition of claim 17, wherein the mechanical property is bulk.

21. The filler composition of claim 17, wherein the mechanical property is tensile stiffness.

22. The filler composition of claim 17, wherein the mechanical property is flexural rigidity.

23. The filler composition of claim 17, wherein the mechanical property is porosity.

24. The filler composition of claim 17, wherein the mechanical property is burst.

25. The filler composition of claim 17, wherein the mechanical property is tear strength.

26. The filler composition of claim 17, wherein the mechanical property is tensile strength in the "Z" direction.

27. The filler composition of any one of claims 1-10, wherein the microfibrillated cellulose has a modal fiber particle size ranging from about 0.1 μιη to 500 μιη.

28. The method of any one of claims 1 to 10, wherein microfibrillated cellulose has a modal fiber particle size of at least about 0.5 μιη, at least about 10 μιη, at least about 50 μιη, at least about 100 μιη, at least about 150 μιη, at least about 200 μιη, at least about 300 μιη, or at least about 400 μιη.

29. The filler composition according to any one of claims 1 to 10, wherein the median particle size (d ₅₀ ) In the range of about 3 μm toAbout 50 μm, or about 5 μm to about 30 μm, or about 10 μm to about 30 μm, or about 15 μm to about 25 μm, or about 20 μm to about 30 μm, or about 3 μm to about 15 μm, or about 5 μm to about 10 μm, or about 2 μm to about 6 μm, and particularly 3 μm to 6 μm is preferred.

30. The filler composition according to any one of claims 1 to 10, wherein the median particle size (d ₅₀ ) Ranging from about 3 μm to about 6 μm.

31. The filler composition according to any one of claims 1 to 10, wherein the one or more microporous inorganic particulate materials and microfibrillated cellulose composite may be combined with one or more dispersants, such as those selected from the group comprising: homopolymers or copolymers of polycarboxylic acids and/or salts or derivatives thereof, based on esters of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid; acrylamide or acrylate, methyl methacrylate or mixtures thereof; alkaline polyphosphates, phosphonic, citric and tartaric acids and salts or esters thereof; or a mixture thereof.

32. The filler composition according to any one of claims 1 to 10, wherein the one or more microporous inorganic particulate materials and microfibrillated cellulose composite are provided in the form of a powder.

33. The filler composition according to any one of claims 1 to 10, wherein the one or more microporous inorganic particulate materials and microfibrillated cellulose composite are provided in the form of a suspension.

34. The filler composition of claim 33, wherein the suspension is an aqueous suspension.

35. The filler composition of claim 34, wherein the aqueous suspension is a pumpable liquid.

36. The filler composition of any one of claims 1-10, wherein the one or more microporous inorganic particulate materials comprise a blend of a first microporous inorganic particulate material and a second microporous inorganic particulate material, wherein the weight ratio of the first microporous inorganic particulate material to the second microporous inorganic particulate material may range from about 10:90 to about 90:10.

37. The filler composition of any one of claims 1-10, wherein the one or more microporous inorganic particulate materials comprise a blend of a first microporous inorganic particulate material and a second microporous inorganic particulate material, wherein the weight ratio of the first microporous inorganic particulate material to the second microporous inorganic particulate material may range from about 20:80 to about 80:20.

38. The filler composition of any one of claims 1-10, wherein the one or more microporous inorganic particulate materials comprise a blend of a first microporous inorganic particulate material and a second microporous inorganic particulate material, wherein the weight ratio of the first microporous inorganic particulate material to the second microporous inorganic particulate material may range from about 25:75 to about 75:25.

39. The filler composition of any one of claims 1-10, wherein the one or more microporous inorganic particulate materials comprise a blend of a first microporous inorganic particulate material and a second microporous inorganic particulate material, wherein the weight ratio of the first microporous inorganic particulate material to the second microporous inorganic particulate material may range from about 40:60 to about 60:40.

40. The filler composition of any one of claims 1-10, wherein the one or more microporous inorganic particulate materials comprise a blend of a first microporous inorganic particulate material and a second microporous inorganic particulate material, wherein the weight ratio of the first inorganic particulate material to the second inorganic particulate material may range from about 50:50.

41. The filler composition of any one of claims 1-10, further comprising a binder.

42. The filler composition of claim 41, wherein the binder is an inorganic or organic binder.

43. The filler composition of claim 41, wherein the binder is an alkali metal silicate.

44. The filler composition of claim 43, wherein the alkali metal silicate is sodium silicate.

45. The filler composition of claim 43, wherein the alkali metal silicate is potassium silicate.

46. The filler composition of any one of claims 1 to 10, wherein the weight ratio of microfibrillated cellulose to the one or more microporous inorganic particulate materials on a dry weight basis is 1:5 to 5:1.

47. The filler composition of any one of claims 1 to 10, wherein the weight ratio of microfibrillated cellulose to the one or more microporous inorganic particulate materials on a dry weight basis is 1:3 to 3:1.

48. The filler composition of any one of claims 1 to 10, wherein the weight ratio of microfibrillated cellulose to the one or more microporous inorganic particulate materials on a dry weight basis is 1:2 to 2:1.

49. The filler composition of any one of claims 1 to 10, wherein the weight ratio of microfibrillated cellulose to the one or more microporous inorganic particulate materials on a dry weight basis is 1:1.5 to 1.5:1.

50. The filler composition of any one of claims 1-10, wherein the weight ratio of microfibrillated cellulose to the one or more microporous inorganic particulate materials on a dry weight basis is about 1:1.

51. The filler composition of any one of claims 1 to 10, wherein the total content of the one or more microporous inorganic particulate materials is present in an amount of 10 wt% to 95 wt%, based on the dry weight of the filler composition.

52. The filler composition of any one of claims 1 to 10, wherein the total content of the one or more microporous inorganic particulate materials is present in an amount of 15 wt% to 90 wt%, based on the dry weight of the filler composition.

53. The filler composition of any one of claims 1 to 10, wherein the total content of the one or more microporous inorganic particulate materials is present in an amount of 20 wt% to 75 wt%, based on the dry weight of the filler composition.

54. The filler composition of any one of claims 1 to 10, wherein the total content of the one or more microporous inorganic particulate materials is present in an amount of 25 wt% to 67 wt%, based on the dry weight of the filler composition.

55. The filler composition of any one of claims 1 to 10, wherein the total content of the one or more microporous inorganic particulate materials is present in an amount of 33 wt% to 50 wt%, based on the dry weight of the filler composition.

56. A method of preparing a papermaking furnish comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials, the method comprising the steps of:

adding the one or more microporous inorganic particulate materials to the papermaking furnish;

adding the MFC to the papermaking furnish;

wherein the MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without the microfibrillated cellulose and the one or more microporous inorganic particulate materials.

57. The method of claim 56, wherein the MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose.

58. A method of preparing a papermaking furnish comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials, the method comprising the steps of:

Adding a filler composition comprising MFC and the one or more microporous inorganic particulate materials to the papermaking furnish;

59. A process according to claim 58, wherein the MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose.

60. A method of making paper or paperboard from a papermaking furnish comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials, the method comprising the steps of:

adding a filler composition comprising MFC and the one or more microporous inorganic particulate materials to the papermaking furnish; wherein the filler composition imparts improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without the MFC and the one or more microporous inorganic particulate materials.

61. The method of claim 60, wherein the MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose.

62. A method of making paper or paperboard from a papermaking furnish comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials, the method comprising the steps of:

adding MFC to the papermaking furnish;

63. The method of claim 62, wherein the MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose.

64. A method of making paper or paperboard having improved mechanical properties, the improvement comprising: preparing a papermaking furnish for producing paper or paperboard; preparing a filler composition comprising microfibrillated cellulose (MFC) and one or more microporous inorganic particulate materials; adding the filler composition to the papermaking furnish; producing paper or paperboard from the papermaking furnish by dewatering and drying the papermaking furnish; wherein the filler composition imparts improved mechanical properties to the paper or paperboard compared to paper and paperboard products made from the same papermaking furnish without MFC and microporous inorganic particulate material.

65. The method of claim 64, wherein the MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose.

66. A method of making paper or paperboard having improved mechanical properties, the improvement comprising: preparing a papermaking furnish for producing paper or paperboard; adding one or more microporous inorganic particulate materials to the papermaking furnish; adding microfibrillated cellulose (MFC) to the papermaking furnish; producing paper or paperboard from the papermaking furnish by dewatering and drying the papermaking furnish; wherein the MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without MFC and microporous inorganic particulate materials.

67. The method of claim 66, wherein the MFC is obtained by a co-milling process using the same or different microporous inorganic particulate material and/or conventional non-agglomerated inorganic particulate material and a fibrous substrate comprising cellulose; and wherein the MFC and the one or more microporous inorganic particulate materials impart improved mechanical properties to the paper or paperboard as compared to paper and paperboard products made from the same papermaking furnish without MFC and the one or more microporous inorganic particulate materials.

68. The method of any one of claims 56 to 67, wherein the one or more microporous inorganic particulate materials are selected from the group comprising: calcined clay, kaolin, kaolinite, amorphous aluminum silicate, scalenohedral precipitated calcium chloride, aragonite precipitated calcium carbonate, chemically aggregated filler material, diatomaceous earth, or ground expanded perlite.

69. The method of any one of claims 56 to 67, wherein said microporous inorganic material comprises calcined clay.

70. The method of any one of claims 56 to 67, wherein said microporous inorganic material comprises kaolin.

71. The method of any one of claims 56 to 67, wherein said microporous inorganic material comprises kaolinite.

72. The method of any one of claims 56 to 67, wherein said microporous inorganic material comprises calcined clay.

73. The method of any one of claims 56 to 67, wherein said microporous inorganic material comprises amorphous aluminum silicate.

74. The method of any one of claims 56 to 67, wherein said microporous inorganic material comprises scalenohedral precipitated calcium carbonate.

75. The method of any one of claims 56 to 67, wherein said microporous inorganic particulate material comprises at least two of calcined clay, kaolin, kaolinite, amorphous aluminum silicate, scalenohedral precipitated calcium chloride, aragonite precipitated calcium carbonate, chemically aggregated filler material, diatomaceous earth, ground expanded perlite.

76. The method according to any one of claims 56 to 67, wherein the papermaking furnish comprises one or more pulps selected from softwood pulps.

77. The method according to claim 76 wherein the softwood pulp is selected from the group consisting of: spruce, pine, fir, larch and hemlock or mixed softwood pulp.

78. The method according to any one of claims 56 to 67, wherein the papermaking furnish comprises one or more pulps selected from hardwood pulp.

79. The method of claim 78, wherein the hardwood pulp is selected from the group comprising eucalyptus, aspen and birch, or mixed hardwood pulp.

80. The method of any one of claims 56 to 67, wherein the pulp source of the papermaking furnish is selected from the group comprising: eucalyptus pulp, spruce pulp, pine pulp, beech pulp, hemp pulp, acacia, cotton pulp and mixtures thereof.

81. The method of any one of claims 56 to 67, wherein the pulp source of the papermaking furnish is selected from the group comprising: nordic pine, black spruce, radiata pine, southern pine, enzyme treated Nordic pine, douglas fir, dissolving pulp, birch, eucalyptus, acacia, mixed European hardwood, mixed Thailand hardwood, paper towel dust, cotton, abaca, sisal, bagasse, kenaf, miscanthus, sorghum, arundo and flax.

82. The method of any one of claims 56 to 67, wherein said mechanical property is selected from one or more of tensile strength, tensile elongation, bulk, tensile stiffness, flexural stiffness, porosity, burst and tear strength, and tensile strength in the "Z" direction.

83. The method of claim 82, wherein the mechanical property is tensile strength.

84. The method of claim 82, wherein the mechanical property is tensile elongation.

85. The method of claim 82, wherein the mechanical property is bulk.

86. The method of claim 82, wherein the mechanical property is tensile stiffness.

87. The method of claim 82, wherein the mechanical property is flexural rigidity.

88. The method of claim 82, wherein the mechanical property is porosity.

89. The method of claim 82, wherein the mechanical property is burst.

90. The method of claim 82, wherein the mechanical property is tear strength.

91. The method of claim 82, wherein the mechanical property is tensile strength in the "Z" direction.

92. The method of any one of claims 56-67, wherein said microfibrillated cellulose has a modal fiber particle size ranging from about 0.1 μιη to 500 μιη.

93. The method of any one of claims 56 to 67, wherein microfibrillated cellulose has a modal fiber particle size of at least about 0.5 μm, at least about 10 μm, at least about 50 μm, at least about 100 μm, at least about 150 μm, at least about 200 μm, at least about 300 μm, or at least about 400 μm.

94. The method of any one of claims 56 to 67, wherein the median particle size (d ₅₀ ) Ranging from about 3 μm to about 50 μm, or from about 5 μm to about 30 μm, or from about 10 μm to about 30 μm, or from about 15 μm to about 25 μm, or from about 20 μm to about 30 μm, or from about 3 μm to about 15 μm, or from about 5 μm to about 10 μm, or from about 2 μm to about 6 μm, and particularly preferably 3 μmm to 6 μm.

95. The method of any one of claims 56 to 67, wherein said one or more microporous mineral composite materials have a median particle size (d) ranging from about 3 μιη to about 6 μιη ₅₀ )。

96. The method of any one of claims 56 to 67, wherein the one or more microporous inorganic particulate materials and microfibrillated cellulose composite may be combined with one or more dispersants, such as those selected from the group comprising: homopolymers or copolymers of polycarboxylic acids and/or salts or derivatives thereof, based on esters of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid; acrylamide or acrylate, methyl methacrylate or mixtures thereof; alkaline polyphosphates, phosphonic, citric and tartaric acids and salts or esters thereof; or a mixture thereof.

97. The method of any one of claims 56 to 67, wherein the one or more microporous inorganic particulate materials and microfibrillated cellulose composite are provided in the form of a powder.

98. The method of any one of claims 56 to 67, wherein the one or more microporous inorganic particulate materials and microfibrillated cellulose composite are provided in suspension.

99. The method of claim 98, wherein the suspension is an aqueous suspension.

100. The method of claim 99, wherein the aqueous suspension is a pumpable liquid.

101. The method of any one of claims 56 to 67, wherein the one or more microporous inorganic particulate materials comprise a blend of a first microporous inorganic particulate material and a second microporous inorganic particulate material, wherein the weight ratio of the first microporous inorganic particulate material to the second microporous inorganic particulate material may range from about 10:90 to about 90:10.

102. The method of any one of claims 56 to 67, wherein the one or more microporous inorganic particulate materials comprise a blend of a first microporous inorganic particulate material and a second microporous inorganic particulate material, wherein the weight ratio of the first microporous inorganic particulate material to the second microporous inorganic particulate material may range from about 20:80 to about 80:20.

103. The method of any one of claims 56 to 67, wherein the one or more microporous inorganic particulate materials comprise a blend of a first microporous inorganic particulate material and a second microporous inorganic particulate material, wherein the weight ratio of the first microporous inorganic particulate material to the second microporous inorganic particulate material may range from about 25:75 to about 75:25.

104. The method of any one of claims 56 to 67, wherein the one or more microporous inorganic particulate materials comprise a blend of a first microporous inorganic particulate material and a second microporous inorganic particulate material, wherein the weight ratio of the first microporous inorganic particulate material to the second microporous inorganic particulate material may range from about 40:60 to about 60:40.

105. The method of any one of claims 56 to 67, wherein the one or more microporous inorganic particulate materials comprise a blend of a first microporous inorganic particulate material and a second microporous inorganic particulate material, wherein the weight ratio of the first inorganic particulate material to the second inorganic particulate material may range from about 50:50.

106. The method of any one of claims 56 to 67, further comprising an adhesive.

107. The method of claim 106, wherein the binder is an inorganic or organic binder.

108. The method of claim 106, wherein the binder is an alkali silicate.

109. The method of claim 108, wherein the alkali metal silicate is sodium silicate.

110. The method of claim 108, wherein the alkali metal silicate is potassium silicate.

111. The method of any one of claims 56 to 67, wherein the weight ratio of microfibrillated cellulose to the one or more microporous inorganic particulate materials is 1:5 to 5:1 on a dry weight basis.

112. The method of any one of claims 56 to 67, wherein the weight ratio of microfibrillated cellulose to the one or more microporous inorganic particulate materials is 1:3 to 3:1 on a dry weight basis.

113. The method of any one of claims 56 to 67, wherein the weight ratio of microfibrillated cellulose to the one or more microporous inorganic particulate materials is 1:2 to 2:1 on a dry weight basis.

114. The method of any one of claims 56 to 67, wherein the weight ratio of microfibrillated cellulose to the one or more microporous inorganic particulate materials on a dry weight basis is 1:1.5 to 1.5:1.

115. The method of any one of claims 56 to 67, wherein the weight ratio of microfibrillated cellulose to the one or more microporous inorganic particulate materials on a dry weight basis is about 1:1.

116. The method of any one of claims 56 to 67, wherein the total content of the one or more microporous inorganic particulate materials is present in an amount of 10 wt% to 95 wt%, based on the dry weight of the filler composition.

117. The method of any one of claims 56 to 67, wherein the total content of the one or more microporous inorganic particulate materials is present in an amount of 15 wt% to 90 wt%, based on the dry weight of the filler composition.

118. The method of any one of claims 56 to 67, wherein the total content of the one or more microporous inorganic particulate materials is present in an amount of 20 wt% to 75 wt%, based on the dry weight of the filler composition.

119. The method of any one of claims 56 to 67, wherein the total content of the one or more microporous inorganic particulate materials is present in an amount of 25 wt% to 67 wt%, based on the dry weight of the filler composition.

120. The method of any one of claims 56 to 67, wherein the total content of the one or more microporous inorganic particulate materials is present in an amount of 33 wt% to 50 wt%, based on the dry weight of the filler composition.