阅读说明：本技术 颗粒状纤维素产品 (Granular cellulose product ) 是由 尤哈纳·阿霍拉 K·卡里萨米尔 克里斯托斯·兰普塔斯 P·海斯卡 米卡·苏万托 于 2019-07-19 设计创作，主要内容包括：本发明涉及颗粒状微原纤化纤维素产品,该颗粒状微原纤化纤维素产品包含源自农业生物质的微原纤化纤维素,基于所述产品的干固体含量,所述微原纤化纤维素产品包含≤75wt％、优选地≤70wt％的纤维素,其中所述颗粒状微原纤化纤维素产品具有500kg/m～3-1200kg/m～3的堆积密度；通过具有带有孔16的不锈钢圆筒或带有孔15的漏斗的Copley scientific粉末流动性测试仪测量的5ml/s-60ml/s的流动性；以及基于总微原纤化纤维素产品的至多60wt％的含水量。本发明还涉及颗粒状微原纤化纤维素产品的制造,以及在纸产品和纸板产品中的用途及纸产品和纸板产品的制造。(The present invention relates to a particulate microfibrillated cellulose product comprising microfibrillated cellulose derived from agricultural biomass, based on which productA dry solids content of an article, said microfibrillated cellulose product comprising less than or equal to 75 wt%, preferably less than or equal to 70 wt% cellulose, wherein said particulate microfibrillated cellulose product has a weight of 500kg/m 3 ‑1200kg/m 3 (ii) the bulk density of; flowability of 5ml/s to 60ml/s as measured by a Copley scientific powder flowability tester having a stainless steel cylinder with holes 16 or a funnel with holes 15; and a moisture content of at most 60 wt% based on the total microfibrillated cellulose product. The invention also relates to the manufacture of particulate microfibrillated cellulose product and to the use in and the manufacture of paper and board products.)

1. A particulate microfibrillated cellulose product comprising microfibrillated cellulose derived from agricultural biomass, said microfibrillated cellulose product comprising less than or equal to 75 wt%, preferably less than or equal to 70 wt% cellulose based on dry solids content of the product,

wherein the particulate microfibrillated cellulose product has

500kg/m³-1200 kg/m³(ii) the bulk density of;

flowability of 5ml/s to 60ml/s as measured by a Copley scientific powder flowability tester having a stainless steel cylinder with holes 16 or a funnel with holes 15; and a moisture content of at most 60 wt% based on the total microfibrillated cellulose product.

2. The particulate microfibrillated cellulose product according to claim 1, wherein the microfibrillated cellulose product comprises a total of ≥ 25 wt% hemicellulose, pectin, lignin, protein and optionally ash, based on the dry solids content of the product.

3. The particulate microfibrillated cellulose product according to claim 1 or 2, wherein said microfibrillated cellulose product comprises in addition to cellulose:

from 8% to 25%, preferably from 8% to 20% or from 8% to 15% by weight of hemicellulose,

1 to 15 wt%, preferably 1 to 10 wt% or 1 to 8 wt% of pectin,

0 to 12 wt%, preferably 0 to 10 wt% or 0 to 8 wt% lignin, and

0 wt% to 8 wt%, preferably 0 wt% to 6 wt% or 0 wt% to 5 wt% of protein.

4. The particulate microfibrillated cellulose product according to any one of claims 1-3, wherein the microfibrillated cellulose product has a water content of at most 55 wt%, preferably at most 50 wt%, preferably at most 45 wt%, preferably at most 40 wt%, preferably at most 35 wt%, preferably at most 30 wt%, preferably at most 25 wt%, preferably at most 20 wt%, preferably at most 15 wt%, preferably at most 10 wt%, based on the total microfibrillated cellulose product.

5. The particulate microfibrillated cellulose product of any one of claims 1-4, wherein the microfibrillated cellulose product has 550kg/m³-1000 kg/m³Preferably 600kg/m³-900kg/m³Preferably 650kg/m³-850 kg/m³And preferably 650kg/m³-800 kg/m³The bulk density of (2).

6. The particulate microfibrillated cellulose product according to any one of claims 1-5, wherein the microfibrillated cellulose product has an average diameter (D50) of 200-6000 μm, preferably 400-5000 μm, preferably 600-4000 μm, preferably 800-3000 μm, preferably 1000-2000 μm, preferably 1100-1900 μm and preferably 1200-1800 μm.

7. A microfibrillated cellulose product according to any one of claims 1-6, wherein the microfibrillated cellulose product does not comprise added additives to prevent keratinisation.

8. A microfibrillated cellulose product according to any one of claims 1-6, wherein the particulate microfibrillated cellulose product has a microbial growth in delta microbiology of less than 2log, preferably less than 1log, within at least one week, preferably within two weeks, preferably within one month, preferably within at least two months, when stored in a sealed package preventing ingress of moisture at a temperature of 15-25 ℃.

9. The particulate microfibrillated cellulose product according to any one of claims 1 to 8, wherein the microfibrillated cellulose product has a flowability of 10ml/s-50ml/s, preferably 15ml/s-45ml/s, preferably 20ml/s-40ml/s, preferably 35ml/s-40ml/s, measured by a Copley scientific powder flowability tester having a stainless steel cylinder with holes 16 or a funnel with holes 15.

10. The particulate microfibrillated cellulose product of any one of claims 1-9, wherein said agricultural biomass is derived from a crop selected from the group consisting of: vegetables, fruits, grasses, buckwheat, legumes, and any combination thereof;

preferably selected from the group consisting of: sugar beet; potato; cassava; sweet potato; saposhnikovia divaricata; radish and carrot; ginger; ginseng; onion; tomatoes; cranberry; blueberries; apple, apple; pears; citrus fruits, preferably selected from the group consisting of oranges, limes, lemons and grapefruits; a cereal, preferably selected from corn, wheat, oats, rye, barley, sugar cane and sorghum; buckwheat; peas; legumes, preferably dried beans and/or soybeans, and any combination thereof;

preferably selected from the group consisting of: sugar beet, potato, sugar cane, carrot, cassava, sweet potato, grain such as corn, and any combination thereof.

11. A method of manufacturing a particulate microfibrillated cellulose product according to any one of claims 1-10, comprising the steps of:

providing a microfibrillated cellulose composition derived from agricultural biomass;

optionally dewatering the microfibrillated cellulose composition to obtain a dewatered microfibrillated cellulose composition;

drying the microfibrillated cellulose composition, which optionally has been dewatered, to provide the particulate microfibrillated cellulose product.

12. The method of claim 11, wherein the drying is performed using an apparatus comprising at least one of: fluidized bed dryers, paddle dryers, dispersion dryers, tray dryers, drum dryers, flash dryers, tube dryers and belt filters.

13. The method according to claim 11 or 12, further comprising a crushing step before the drying of the microfibrillated cellulose composition and preferably after the optional dewatering step, to crush the obtained microfibrillated cellulose composition into smaller pieces.

14. The method according to claim 13, further comprising a packaging step prior to the comminuting and drying steps of the microfibrillated cellulose composition and preferably after the optional dewatering step, to package the obtained microfibrillated cellulose composition to allow storage and/or transport of the evacuated microfibrillated cellulose composition.

15. The method according to any one of claims 10-14, wherein the drying is performed at a temperature of 50-95 ℃, preferably 55-90 ℃, preferably 60-85 ℃, preferably 70-85 ℃ and preferably 75-85 ℃.

16. The method according to any one of claims 10-15, wherein the drying is carried out for a period of time of at most 40min, preferably at most 30min, preferably at most 25 min, preferably 5-25 min.

17. A method of making a paper product or a paperboard product, comprising:

providing an aqueous pulp furnish, draining the aqueous pulp furnish to form a wet fibrous web, and drying the wet fibrous web to obtain the paper product; and

providing a particulate microfibrillated cellulose product according to any one of claims 1-10 and redispersing the particulate microfibrillated cellulose product according to any one of claims 1-10 in water to provide dispersed microfibrillated cellulose, and

adding the dispersed microfibrillated cellulose to the aqueous pulp furnish or to the wet paper web.

18. The method according to claim 17, wherein the dispersed microfibrillated cellulose is added to a pulp suspension, preferably to a thin stock or a thick stock.

19. The method according to claim 17 or 18, wherein the dispersed microfibrillated cellulose is added to the aqueous pulp furnish or onto the wet paper web in an amount of about 1kg-100kg microfibrillated cellulose product per ton pulp furnish, preferably about 1 kg/ton-70 kg/ton, preferably about 5 kg/ton-70 kg/ton, preferably 10 kg/ton-50 kg/ton, preferably 15 kg/ton-50 kg/ton, based on the dry solids content of the microfibrillated cellulose product per ton dry solids of the pulp furnish.

20. Use of the particulate microfibrillated cellulose product according to any one of claims 1-10 as a strength additive in the manufacture of a paper or paperboard product, preferably in the manufacture of fine paper, facial tissue or packaging material.

Technical Field

The present invention relates to particulate microfibrillated cellulose product (granulated microfibrillated cellulose product), its manufacture and its use in papermaking.

Background

It has been known to use microfibrillated cellulose in papermaking for some time. The biggest challenge in using microfibrillated cellulose (MFC) in industrial applications is to obtain a transportable microfibrillated cellulose material for subsequent processes. Efforts have been made to commercialize microfibrillated cellulose, because the dehydration of MFC is time and energy consuming due to its gelatinous and water absorbing properties in or with water, and keratinization is easily induced at higher solids content, which damages cellulose fibrils. This results in a significant reduction in performance, for example when used as a paper strength additive.

Known techniques for providing microfibrillated cellulose material involve dewatering and drying. Since water is difficult to remove from MFC, additives may be added to improve the dewatering properties. However, these known processes, i.e. dewatering, drying and additive addition to achieve high solids content, may provide MFC and its degradation of properties that may be brought about in pulp and paper manufacturing processes. Such deteriorated MFC, if used as a paper strengthening agent, will not impart strength to the pulp or the paper produced. When processed MFC is redispersed before or after addition to the papermaking process, the deterioration may provide keratinization. Keratinization can be seen as a significant change in viscosity values during processing, i.e. a decrease in viscosity. Keratinization can be seen as a significant change in viscosity values, i.e. a decrease in viscosity, during the processing of paper production. Due to the problem of keratinization, MFC is usually not too dry, which causes problems and costs for transportation and may even lead to waste production, rather than conversion to value added products.

Most of the research and commercialization work has been put on lignocellulose (wood-based cellulose). However, there is an increasing demand and interest in the efficient use of world resources, and more recent work and research has been put into the secondary streams of the industry. By finding new ways to provide value added products that are easier to handle and transport, our resources can be used more efficiently than is commonly used.

SUMMARY

The present invention introduces a new particulate microfibrillated cellulose (MFC) product which has a low water content, a high solids content and is therefore easy to package, transport, store and handle. When transporting large quantities of MFC product, it is necessary to reduce or minimize the amount of water in the product. The present invention may provide advantages in terms of shelf life, storage temperature and space required. The MFC of the present invention comprises most of the constituents of the raw material, as the processing of the raw material does not extract and/or wash away too much of the initially entering raw material components. Thus, the present invention can use a secondary stream from an industry, such as the agricultural process industry, to provide the MFC of the present invention. Because the present invention uses a large amount of raw materials, less waste is provided that needs to be disposed of, which provides environmental benefits. In addition, the MFC of the present invention provides a more natural ingredient for paper production.

The present invention provides a particulate microfibrillated cellulose (MFC) product with improved flowability for improved handling and transportability without deteriorating its end use properties. The reduction or prevention of hornification after redispersion provides MFC which is more suitable as a paper strengthening agent, for example when used in a papermaking process, as it provides strength to the paper web (paper web) and/or the paper produced. The present invention thus provides an easily redispersible MFC which also has good flow properties in its dehydrated and/or dried state, i.e. the MFC of the present invention is so-called free-flowing. By "free-flowing" is meant herein a dry, granular state having free-flowing characteristics, which provides a product that is easy to handle and pour, which is not gelatinous. The dry, particulate state in the context of the present invention may be a composition, preferably in the form of pellets, granules, compressed tablets or agglomerates, which preferably do not adhere to other surfaces in contact therewith. The particulate MFC product of the invention is a dry product, not in gel or semi-liquid form, which is easy to redisperse and prevents keratinisation without the need to include additives to prevent keratinisation.

The particulate microfibrillated cellulose product of the invention also provides a higher bulk density compared to the known MFC.

The free water content in the particulate microfibrillated cellulose product of the invention is low. The word "free water" is intended herein to mean water that is mobile, i.e., water that is available to the microbial cells and that is not bound to particles or locked within aggregates or similar structures. Free water is moisture that is not retained or absorbed by aggregates or similar structures. Free water is moisture that is removable by air drying under standard conditions and may also be referred to as surface moisture.

The MFC product according to the invention preferably has an improved shelf life. The particulate microfibrillated cellulose product of the invention may be allowed to be stored for at least one week, two weeks, one month, preferably at least two months, without any substantial microbial growth (delta microbial count of less than 1 log) during said period, depending on the storage temperature and the remaining moisture content in the particulate MFC product after drying.

Microbial growth in embodiments of the particulate MFC product according to the present invention preferably has a microbial growth in delta microbial counts of less than 2log (2 log microbial growth as delta microbial quality) or even preferably has a microbial growth in delta microbial counts of less than 1log for at least one week, preferably for at least two weeks, more preferably for at least one month, even more preferably for at least two months, when stored in a sealed package that prevents ingress of moisture at temperatures of 15 ℃ to 25 ℃.

Control of excessive microbial growth can help prevent slime formation, which can disrupt MFC particle form and lead to poor flowability of MFC. The microbial shelf life of MFC can thus be an important quality parameter. Preventing excessive microbial growth may also be important for the use of MFC products in different applications.

The handling of free-flowing MFC products is also an important advantage for users, especially in high volume industries, compared to viscous or gel-like MFC products. The higher solids content makes it easier to transport and transfer at the customer site, such as in a paper mill environment, or in any other industrial environment or use environment. This may additionally save cost and space of the preparation equipment (make-down equipment). Furthermore, for the higher dry solids content obtainable, additives, such as drying additives or additives preventing keratinization, are not necessarily required in the drying step, which saves energy costs, additive costs and allows for simpler processing. The anionicity may also be achieved with or without chemical modification.

With a higher bulk density of the granular product, less space, i.e. volume, is required in the transport.

The present invention relates to the provision of particulate microfibrillated cellulose product derived from sources other than those typically used to provide such materials. Typically wood sources are used for MFC production. The present invention offers the possibility to achieve higher value-added (valorization) of agro-industrial biomass and more efficient utilization of existing resources.

Brief Description of Drawings

Fig. 1 shows 1) a photograph of dehydrated (and dried) microfibrillated cellulose according to a conventional process, named original product, and 2) a photograph of dehydrated and dried microfibrillated cellulose according to the present invention, which has been dried in a fluidized bed, named final product.

Detailed description of the invention

The present invention provides a particulate microfibrillated cellulose product comprising microfibrillated cellulose derived from agricultural biomass. The microfibrillated cellulose composition of the present invention may be used as a reinforcing agent in papermaking. Particulate microfibrillated cellulose product may also be referred to herein as microfibrillated cellulose particles.

Keratinization is a descriptive term for the physical and chemical changes that occur to pulp fibers during drying, primarily shrinkage and the formation of internal hydrogen bonds. Some keratinization may cause irreversible effects.

Keratinization may occur during the production of microfibrillated cellulose (MFC) products. If hornification would occur during manufacture, such materials would become difficult to degrade into dispersions, i.e. redisperse or activate into dispersions, before being added to the pulp furnish of the papermaking process. Thus, MFC that gains a keratinizing effect is undesirable. It may be difficult to obtain high concentrations of MFC due to possible effects of keratinization. It is believed that keratinization may be the reason that concentrated MFC performs less well after rewetting than without concentration, as important performance factors such as strength become compromised.

The present inventors have surprisingly found a particulate microfibrillated cellulose product which is not affected by hornification or which is as less prone to hornification as the known compositions and which is easy to handle and transport. The particulate microfibrillated cellulose product according to the present invention is easily activated and redispersed. This means that it can be easily diluted and dispersed without keratinization after having been provided in the form of granules. The present invention thus provides a particulate microfibrillated cellulose product which can be provided in high concentrations, i.e. high solids content, and which can be easily rewetted before addition to the pulp, and which provides a paper product with sufficient strength.

The particulate microfibrillated cellulose product of the invention comprises microfibrillated cellulose derived from agricultural biomass, said microfibrillated cellulose product comprising less than or equal to 75 wt%, such as less than or equal to 70 wt% cellulose based on the dry solids content of the product,

wherein the particulate microfibrillated cellulose product has

500kg/m³-1200kg/m³(ii) the bulk density of;

flowability of 5ml/s to 60ml/s as measured by Copleyscientific powder flowability tester having stainless steel cylinder with orifice 16 or funnel with orifice 15; and a moisture content of at most 60 wt% based on the total microfibrillated cellulose product.

The product was easily re-dispersed in water. This is true despite the high dry solids content. Therefore, keratinization is not a significant problem for the present invention.

The particulate microfibrillated cellulose product may also comprise a total of ≥ 25 wt%, such as ≥ 30 wt%, hemicellulose, pectin, lignin, protein and ash (if present), based on the total microfibrillated cellulose product.

Based on the dry solids content of the product, the particulate microfibrillated cellulose product may comprise:

from 8% to 25%, preferably from 8% to 20% or from 8% to 15% by weight of hemicellulose,

1 to 15 wt%, preferably 1 to 10 wt% or 1 to 8 wt% of pectin,

0 to 12 wt%, preferably 0 to 10 wt% or 0 to 8 wt% lignin, and

0 wt% to 8 wt%, preferably 0 wt% to 6 wt% or 0 wt% to 5 wt% of protein.

Based on the dry solids content of the product, the microfibrillated cellulose product may comprise:

more than or equal to 30 wt%, such as 50 wt% to 99 wt%, 50 wt% to 69 wt%, or 60 wt% to 90 wt% of cellulose,

1 to 15 wt%, such as 1 to 10 wt%, 1 to 8 wt% or 1 to 5 wt% of pectin,

8-25 wt%, such as 8-20 wt%, 8-15 wt% or 10-20 wt% hemicellulose,

0 wt% to 12 wt%, such as 1 wt% to 12 wt%, 0 wt% to 10 wt%, 0 wt% to 8 wt%, or 5 wt% to 12 wt% lignin,

0 wt% to 15 wt%, such as 1 wt% to 15 wt%, 0 wt% to 10 wt%, 0 wt% to 8 wt%, or 1 wt% to 10 wt% of ash, and

0 wt% to 8 wt%, such as 1 wt% to 8 wt%, 0 wt% to 6 wt%, 0 wt% to 5 wt%, or 1 wt% to 6 wt% of protein. The amount of cellulose is at least 30 wt% based on the dry solids content of the product and may be in the range of 50 wt% to 99 wt%, 60 wt% to 90 wt%, 30 wt% to 99 wt%, 40 wt% to 69 wt%, 45 wt% to 65 wt%, 50 wt% to 60 wt%, 50 wt% to 69 wt%, 55 wt% to 69 wt%, 60 wt% to 69 wt%, or 55 wt% to 65 wt%. The amount of hemicellulose is 8 wt% to 25 wt% based on the dry solids content of the product and may be in the range of 8 wt% to 20 wt% such as 8 wt% to 18 wt%, 8 wt% to 15 wt%, 10 wt% to 18 wt%, 10 wt% to 20 wt%, 10 wt% to 15 wt%, 12 wt% to 18 wt% or 14 wt% to 16 wt%. The amount of pectin is 1 wt% to 15 wt% based on the dry solids content of the product and may be in the range of 1 wt% to 10 wt%, 1 wt% to 8 wt%, 1 wt% to 7 wt%, 1 wt% to 5 wt%, 5 wt% to 10 wt%, 1 wt% to 3 wt% or 1 wt% to 2 wt%. The amount of lignin is 0 wt% to 12 wt% based on the dry solids content of the product and may be in the range of 1 wt% to 12 wt%, 0 wt% to 10 wt%, 5 wt% to 12 wt%, 1 wt% to 10 wt%, 5 wt% to 10 wt%, 0 wt% to 8 wt%, 5 wt% to 8 wt% or 0 wt% to 5 wt%. The amount of ash is 0 wt% to 15 wt%, and may be in the range of 1 wt% to 15 wt%, 0 wt% to 10 wt%, 1 wt% to 10 wt%, 5 wt% to 10 wt%, 0 wt% to 8 wt%, 5 wt% to 8 wt%, or 0 wt% to 5 wt%, based on the dry solids content of the product. The amount of protein is 0 wt% to 8 wt% based on the dry solids content of the product and may be in the range of 1 wt% to 8 wt%, 0 wt% to 6 wt%, 1 wt% to 6 wt%, 0 wt% to 5 wt%, 2 wt% to 5 wt%, 0 wt% to 4 wt%, 2 wt% to 4 wt% or 0 wt% to 3 wt%.

The microfibrillated cellulose product may comprise 50-69 wt% cellulose, 1-10 wt% pectin, 8-15 wt% hemicellulose, 0-5 wt% lignin, 0-5 wt% ash and 0-4 wt% protein based on the dry solids content of the product.

The microfibrillated cellulose product may comprise 55-65 wt% cellulose, 1-7 wt% pectin, 8-15 wt% hemicellulose, 0-5 wt% lignin, 0-5 wt% ash and 0-3 wt% protein based on the dry solids content of the product.

The particulate MFC product may have a water content of at most 60 wt%, such as at most 55 wt%, at most 50 wt%, at most 45 wt%, at most 40 wt%, at most 38 wt%, at most 35 wt%, at most 30 wt%, at most 25 wt%, at most 20 wt%, at most 15 wt% or at most 10 wt%, based on the total amount of the microfibrillated cellulose product.

Handling of MFC product with low water content is easier due to less viscous and high content of MFC is a free flowing material and can be prepared by a simple preparation unit.

The particulate MFC product may have 550kg/m³-1000kg/m³Such as 600kg/m³-900kg/m³、650kg/m³-850kg/m³Or 650kg/m³-800kg/m³The bulk density of (2). Bulk density is defined as the mass per unit volume of material after it has been poured freely into a container, ISO7837: 1992.

The particulate microfibrillated cellulose product may have an average diameter (D50) of 50 μm to 10000 μm, such as 100 μm to 8000 μm, 200 μm to 6000 μm, 400 μm to 5000 μm, 600 μm to 4000 μm, 800 μm to 3000 μm, 1000 μm to 2000 μm, 1100 μm to 1900 μm or 1200 μm to 1800 μm.

The particulate MFC product may be approximately spherical, ellipsoidal or cylindrical in shape, such as approximately spherical or ellipsoidal in shape. If the microfibrillated cellulose product is in an elongated or slightly elongated shape, such as an oval or cylindrical shape, the average length is preferably at most three times the average diameter, preferably at most two times the average diameter, preferably at most 50% longer than the average diameter, and preferably about the same length as the diameter.

The particulate MFC product can have a flowability of 10ml/s to 50ml/s, such as 12ml/s to 45ml/s, 15ml/s to 40ml/s, 20ml/s to 40ml/s, 10ml/s to 30ml/s, 10ml/s to 25ml/s, 12ml/s to 35ml/s, 12ml/s to 25ml/s, 15ml/s to 30ml/s, or 35ml/s to 40ml/s, as measured by a Copley scientific powder flowability tester having a stainless steel cylinder with holes 16 or a funnel with holes 15.

Both flowability and bulk density are important characteristics for particulate microfibrillated cellulose products to achieve a desirable material that can be easily managed and transported.

The microfibrillated cellulose product of the present invention may not comprise any added additives to prevent keratinisation, such as long hydrocarbons, e.g. fatty alcohols and/or fatty acids, wherein the fatty alcohols may be polyols. Examples of such long hydrocarbons are, for example, tall oil, linseed oil, castor oil, olive oil, palm oil, peanut oil, soybean oil, sesame oil, glycerol and any combination thereof. The additive that prevents keratinization enters between and adheres to the fiber and pulp furnish of the microfibrillated cellulose and physically prevents the formation of hydrogen bonds that cause keratinization. The microfibrillated cellulose product of the present invention may not contain any additives at all to prevent keratinisation.

Excessive moisture content of MFC particles may support the growth of typical soil microorganisms, for example. Therefore, a treatment for controlling the growth of such microorganisms is required. If the microbial activity is not controlled, overgrowth may lead to a degradation of the MFC raw material and the particulate end product. MFC production in compositions having a cellulose content of 75 wt% or less or 70 wt% or lessIn the product, the remaining sugars can serve as a nutrient source for the microorganisms. Under anaerobic conditions, microorganisms produce metabolites that are generally undesirable, such as volatile fatty acids. Another unwanted reaction under anaerobic conditions is H₂S gas formation, which may lead to explosion of the MFC storage tanks, or even in H₂The replacement of oxygen in the breathing air by S gas can lead to more serious worker death. The micro-organisms may have an impact on the physical properties of e.g. MFC particles, e.g. the product may suffer from slime problems. Thus, the flow properties of the particles may be reduced. The particles may even stick together. Other problems with microbial growth may also be faced.

It is preferred to provide as natural as possible a particulate MFC product. Depending on the end use of MFC, food preservatives can be used instead of industrial biocides. If MFC is to be used in such food applications, food contact regulations are often the limiting factor if industrial biocides are used. Therefore, it is preferred to add up to very low amounts of biocide so that the biocide dosage level does not compromise or limit any end use application of the MFC product. A typical limiting parameter for MFC biocide dosage levels is the food contact legislation set for MFC containing end products such as food carton boards. The biocide treatment of MFC may not bring unwanted biocide residues to the subsequent manufacturing process. As an example, the amount of halogen-containing compounds needs to be limited because halogen biocide residues from MFC may disrupt additional processes using MFC, such as papermaking processes. It is even more preferred if the particulate MFC product does not comprise an added biocide. If regulations on residues are not limiting factors, a certain amount of biocide may be used. It is possible to use only fungicides, or in some embodiments both fungicides and bactericides. In some embodiments, only bactericides may be used. Fungicides and bactericides are included within the scope of biocides. With the present invention it is possible to provide MFC products with improved shelf life without the need for biocides, or without the need for fungicides, or without the need for bactericides, or without the need for fungicides and bactericides.

It has been found that by drying MFC to a moisture content of < 60%, low or no biocides such as bactericides and/or fungicides may be required in MFC to provide good storage stability.

The microfibrillated cellulose product of the present invention preferably does not comprise additives added in the process of providing said microfibrillated cellulose product. Any biocide that may have been added to the growing agricultural crop, or any additive added in a previous process of providing the agricultural biomass, if it is, for example, a byproduct or secondary stream of another process, such additive should not be construed as an additive added in or included as an additive added in the microfibrillated cellulose product of the invention or its manufacture.

The microfibrillated cellulose product may comprise or consist of only said microfibrillated cellulose and water as dry solids.

The shelf life of the microfibrillated cellulose product may be at least one week, such as at least two weeks, at least one month or at least two months, when stored in a sealed package preventing ingress of moisture at a temperature of about 15-25 ℃. For an acceptable shelf life, the possible microbial growth is less than 2log, more preferably less than 1log (delta microbial number) during said period. In some cases, acceptable microbial growth is less than 3 log. The shelf life of MFC is strongly influenced by the growth rate of the microorganisms. As an example, microbial growth can produce unwanted metabolites, such as Volatile Organic Compounds (VOCs), which can cause sensory problems to MFC and thus further compromise the end use of MFC. Unwanted metabolites may also include microbial toxins, which can compromise process and product safety, and even personnel safety. One key microbial population is the endospore-forming bacteria, which can compromise the hygienic properties of MFC, and in particular, the end use of MFC. As an example, bacterial endospore content can be a key parameter in the production of toilet paper carton boards (boards) for food packaging. In addition, excessive microbial growth may lead to slime formation that can disrupt the MFC particulate form and lead to poor flowability of the MFC. The microbial shelf life of MFC can thus be an important quality parameter. The microbial shelf life may be expressed, for example, as an acceptable growth rate, i.e. the number of microorganisms immediately after the drying step of the MFC compared to the number of microorganisms for a specific storage time. The number of microorganisms immediately after drying may generally be at the same level as the number of microorganisms immediately before the drying step. A delta microbial number of less than 1log indicates no significant microbial growth in the MFC. Delta microbial numbers of less than 2log may also be acceptable. In some cases, even a delta microbial count of less than 3 log may be acceptable. Growth rate values can be calculated by using conventional plate counts (cfu/ml) or some other microorganism monitoring method, such as molecular biology based methods like qPCR (gene/ml) or colorimetric based methods like ATP (pg/ml). For growth values, one or more of total aerobic bacteria, aerobic bacterial endospores, anaerobic bacteria, anaerobic bacterial endospores, and molds and yeasts may be used.

To be able to produce an acceptable microbial shelf life, MFC should be an unaltered material after production and before the drying step. For non-deteriorated materials, microbial levels<10⁴Are generally considered to be non-spoiled. The use of a particulate MFC product may set even more stringent requirements on the microbial content before or just after drying.

Particulate microfibrillated cellulose product is stated to be derived from agricultural biomass. The agricultural biomass is preferably derived from an agricultural crop that may have been processed, such as agricultural waste, byproducts, or a secondary stream of a processing step. It should be noted that the cellulose-containing material herein may be a secondary stream or residue from an early processing step of an agricultural crop.

The agricultural biomass may be in the form of pomace, clippings, fragmented material, crushed material or beaten material.

The agricultural biomass may be derived from a crop selected from the group consisting of: vegetables, fruits, grasses, buckwheat, legumes, and any combination thereof;

preferably selected from the group consisting of: sugar beet; potato; cassava; sweet potato; saposhnikovia divaricata; radish and carrot; ginger; ginseng; onion; tomatoes; cranberry; blueberries; apple, apple; pears; citrus fruits, preferably selected from the group consisting of oranges, limes, lemons and grapefruits; a cereal, preferably selected from corn, wheat, oats, rye, barley, sugar cane and sorghum; buckwheat; peas; legumes, preferably dried beans and/or soybeans, and any combination thereof;

preferably selected from the group consisting of: sugar beet, potato, sugar cane, carrot, cassava, sweet potato, grain such as corn, and any combination thereof.

The agricultural biomass may comprise at least 10 wt% cellulose, preferably at least 20 wt% cellulose, based on the dry solids content of the biomass.

Microfibrillar cellulose (MFC) may also be referred to as nanofibrillar cellulose (NFC), nanocellulose, nanofibrillated cellulose, cellulose nanofibril, nanofibrillated cellulose, microfibrillated cellulose or Cellulose Nanofibril (CNF). These terms may be used interchangeably herein. The dimensions of the MFC fibers may vary depending on the specific manufacturing process.

The microfibrillated cellulose material of the product of the invention is obtained as cellulose microfibrils or cellulose microfibril bundles. The length of the microfibrils in the microfibrillated material is typically more than >1 μm, preferably 1 μm-200 μm, even more preferably 10 μm-100 μm, most preferably 10 μm-60 μm. The diameter of the individual microfibrils may be in the range of 2 nm-200 nm, preferably 2 nm-100 nm, more preferably 4 nm-70 nm, even more preferably 5 nm-40 nm. Microfibrillated cellulose material may typically comprise bundles of 10-50 microfibrils, typically with a diameter <1 μm.

Agricultural biomass is used as a raw material, which may contain some microorganisms, in particular microorganisms originating from the soil.

The particulate microfibrillated cellulose product of the present invention may be obtained by a manufacturing method comprising the steps of:

providing a microfibrillated cellulose composition derived from agricultural biomass;

optionally dewatering the microfibrillated cellulose composition to obtain a dewatered microfibrillated cellulose composition;

drying the microfibrillated cellulose composition, which optionally has been dewatered, to provide a particulate microfibrillated cellulose product.

The shape of the MFC product may be provided before, during or after the drying step. The MFC material may be shaped such as to become particulate form. The shaping can be pre-or post-structuring of the MCF to provide a desired shape, such as pellets, granules, flakes, or agglomerates. The shaping may be performed by compacting or compressing the MFC material. In one embodiment, the MFC is preformed prior to the drying step and provides a particulate MFC product after drying. In another embodiment, the dried MFC may be formed into a granular MFC product form after drying. In one embodiment, the particulate MFC product is provided after drying without any pre-or post-shaping step.

Drying may be performed using air or other gas, which may be heated to perform the drying step. Drying can be carried out with good circulation of air or other gas. Air or other gas circulation may provide air suspension, other gas suspension, or mixing motion of the drying material to provide a dried MFC product. Thus, the drying step may provide some simultaneous heating and mixing or suspension of the composition to provide a dried MFC product.

The MFC entering the drying step preferably has a dry solids content of 10 wt% to 35 wt%.

From a microbiological control point of view, the drying step is preferably completed within 14 days of providing MFC, such as within 10 days, 7 days, 5 days, 4 days, 3 days, 2 days, or 1 day, including optional dehydration. The drying step is preferably carried out within 24h, preferably within 12h, preferably within 6h, preferably within 4h, preferably within 2h, preferably within 1h of providing MFC, including optional dehydration, and even more preferably without any delay or immediate transfer to the drying step. The drying step is preferably done as early as possible after the production of the MFC composition to reduce spoilage due to microbial growth. The produced MFC composition may be packaged into vacuum packaging prior to a drying step, which may need to be performed at a later stage, to increase durability. If the MFC composition is vacuum packed before drying, it preferably has a solid content of about 10 wt% to 35 wt%.

The drying step may use equipment including a fluidized bed (dryer), a paddle dryer, a dispersion dryer, a tray dryer, a drum dryer, a flash dryer, and a tube dryer. In embodiments, a belt filter may be used, where it may be a combination of mechanical dewatering and drying.

The method may further comprise a crushing (disintegration) step prior to drying of the microfibrillated cellulose composition to crush the obtained microfibrillated cellulose composition into smaller pieces. This is particularly desirable if the microfibrillated cellulose composition has been vacuum packed before drying. The comminuting step may be carried out after the optional dewatering step. Crushing in this step is intended to result in the formation of smaller pieces of material. The material may be shredded or torn, for example, to comminute the material. The pulverization in this step is preferably carried out mechanically. In comminution, the material is produced in smaller pieces and provides a more finely divided material. Comminution may be carried out by any suitable step or device such as an extruder, impeller and/or perforated plate.

The comminuting step can also be provided prior to the optional dewatering step. The comminuting step can also be included both before the optional dewatering step and after the optional dewatering step. After MFC production, the process steps for comminution may be as follows: pulverizing, mechanically dehydrating, pulverizing, and (heat) drying; crushing, (mechanical) dewatering, (thermal) drying; mechanical dehydration, pulverization, and (thermal) drying; pulverizing, (hot) drying; or any other combination of different steps.

The free-flowing granular state may include processing MFC using a combination of compression, extrusion, cutting, blowing and milling to provide the granular MFC product of the present invention. Free-flowing particulate MFC may be obtained using the processes disclosed above, including drying and optionally crushing, and/or shaping of the MFC material.

The drying step can be performed at a temperature of 45 ℃ to 99 ℃, such as 50 ℃ to 95 ℃, 55 ℃ to 90 ℃, 60 ℃ to 85 ℃, 70 ℃ to 85 ℃, or 75 ℃ to 85 ℃.

The drying step may be performed for a period of up to 40min, such as up to 30 minutes, up to 25 minutes, or 5 minutes to 25 minutes.

For example, during drying in the drying step, the water present in the MFC composition may evaporate a relatively low amount of water from the product during the first 5 minutes of the process, after which a major part of the total evaporated water content may leave the MFC composition during about the next 15 minutes, and then from about 20 minutes from the start of drying, evaporate very little water of the MFC composition again, since the water remaining in the composition at this stage is tightly bound within the structure.

The particulate microfibrillated cellulose composition of the present invention may for example be used for making paper products or paperboard products. Also included herein are paper products or paperboard products comprising the microfibrillated cellulose product. The paper or paperboard product of the invention may be selected from the group consisting of fine paper, printing paper, paper towels, facial tissues and packaging materials such as food packaging materials.

Papermaking can be divided into several sections. Pulp is provided. The pulp may be refined and/or may be mixed in water, e.g. with other additives, to make a pulp furnish. The pulp furnish may be supplied as a wet paper web from which water is drained, which may be pressed and dried, and finally wound into large rolls.

"pulp" typically refers to fibrous cellulosic material. Pulp may also refer to cellulosic fibers, non-cellulosic polymeric fibers, or any combination thereof. Suitable cellulose fibers for the production of pulp are all conventional grades, such as mechanical pulp, bleached and unbleached chemical pulp, recycled pulp and paper stock obtained from all annual plants. Mechanical pulps include, for example, groundwood pulp (ground wood), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), Alkaline Peroxide Mechanical Pulp (APMP), groundwood pulp produced by pressure grinding, semichemical pulp, high yield chemical pulp, and Refined Mechanical Pulp (RMP). Examples of suitable chemical pulps are sulphate pulp, sulphite pulp and alkali pulp. Unbleached chemical pulp, also known as unbleached sulphate pulp (kraft pulp), may be used in particular. In addition to, or instead of, cellulose fibers, the pulp may include non-cellulosic polymeric fibers, such as fibers of polyethylene, polypropylene, or polyester, in the form of, for example, monocomponent fibers or bicomponent fibers.

"pulp furnish" refers to a mixture of pulp and water. The pulp furnish may also be referred to herein as pulp slurry. Pulp furnish is prepared in practice using water, which may be partially or completely recirculated from the paper machine. It may be treated or untreated white water, or a mixture of such water qualities. The pulp furnish may contain interfering substances, such as fillers. The filler content of the paper may be up to about 40% by weight. Suitable fillers are, for example, clays, kaolin, natural and precipitated chalk, titanium dioxide, talc, calcium sulfate, barium sulfate, aluminum oxide, satin white or mixtures of the stated fillers. The aqueous pulp furnish may contain recycled fibers and/or virgin fibers (virgin fibers).

Provided herein is a method of making a paper product, comprising:

providing an aqueous pulp furnish, draining the aqueous pulp furnish to form a wet fibrous web, and drying the wet fibrous web to obtain a paper product or a paperboard product; and

providing a particulate microfibrillated cellulose product of the invention and redispersing the particulate microfibrillated cellulose product of the invention in water to provide dispersed microfibrillated cellulose;

the dispersed microfibrillated cellulose is added to an aqueous pulp furnish or to a wet paper web.

Alternatively, the method of manufacturing a paper product may comprise the steps of:

providing an aqueous pulp furnish, draining the aqueous pulp furnish to form a wet fibrous web, and drying the wet fibrous web to obtain a paper product or a paperboard product; and

the particulate microfibrillated cellulose product of the present invention is provided and the particulate microfibrillated cellulose is added to the aqueous pulp furnish.

The particulate microfibrillated cellulose product or microfibrillated cellulose dispersion may be added to the pulp suspension, preferably to the thin stock or the thick stock.

Optionally, the particulate MFC product may be added to the dry fiber furnish and thereby wetted and redispersed with the paper or paperboard making furnish.

The microfibrillated cellulose dispersion may be added to the aqueous pulp furnish or onto the wet paper web in an amount of about 1kg-100kg microfibrillated cellulose composition per ton pulp furnish, preferably about 1 kg/ton-70 kg/ton, preferably about 5 kg/ton-70 kg/ton, preferably 10 kg/ton-50 kg/ton, preferably 15 kg/ton-50 kg/ton, based on dry solids of the microfibrillated cellulose composition per ton pulp furnish. The same amount can be used for the particulate microfibrillated cellulose product added to the dry or aqueous pulp furnish.

The particulate microfibrillated cellulose product of the present invention may be used as a strength additive in the manufacture of a paper product or a paperboard product. Facial tissues are herein included in the paper product. The paper or paperboard products produced may include, for example, fine paper, printing paper, paper towels, facial tissues, and packaging materials.

Examples

The analysis method comprises the following steps:

1.1 flowability measurement

Flowability was measured by gravimetric method, where 200mL or 180mL of MFC sample flowed freely through a cylinder or funnel and the flow rate was monitored. The speed as a function of time was monitored via weighing the material flowing through the cylinder/funnel. A Copley scientific powder flowability tester was used for flowability measurements (stainless steel cylinder with hole 16 and funnel with hole 15, respectively).

1.2 bulk Density measurement

Bulk density was measured by accurately filling a 100mL container with the granular MFC product and weighing the contents. The measurement was repeated three times, and the average of the results was calculated.

1.3 dimensional characterization

Particle size distribution: the particle size distribution was determined by sieve analysis (for the product). The Engelsmann JEL 200 device was used for 5 minutes. This is also used for particle size measurement of particulate MFC products, such as determination of average particle size (D50).

1.4 viscosity

Viscosity values (mPa, cp) refer to the viscoelastic properties of a substance and/or substances (a substance and/or substances) in a selected solvent. It depends on different parameters such as structure, chemical composition, molecular weight of the substance and measurement temperature.

For viscosity measurements, 1 wt% samples were prepared according to standard laboratory protocols. The pH of the 1 wt% sample was adjusted to 8-9 with NaOH or HCl. The viscosity was measured at 50rpm and 100rpm at 25 ℃ using a spindle (spindel) with blade geometry (Brookfield V-72, V-73 or V-75). Brookfield viscosity was measured using a Brookfield DV-II viscometer according to the Equipment specific instruction manual.

Table 1.

Example 1: flow properties and bulk density of dried MFC samples

Three MFC samples with different solid contents were prepared with fluidized bed drying. The chemical composition of the dried MFC in weight% is as follows: 66 wt% cellulose, 10 wt% hemicellulose, 7 wt% lignin and 2 wt% pectin. The pre-treatment step is carried out before drying. The purpose of the pre-treatment step is to break up 22 wt% of the MFC material into small wet particles, which are easily dried with a fluid bed. Photographs of the pre-treated material and the treated material are shown in figure 1.

The flowability and bulk density values of the sugar beet MFC samples of different solids content are summarized in table 2. Flowability was measured by gravimetric method, where a 200mL sample of MFC flowed freely through a cylinder or funnel and the flow rate was monitored. The speed as a function of time was monitored via weighing the material flowing through the cylinder/funnel. A Copley scientific powder flowability tester was used for flowability measurements (stainless steel cylinder with hole 16 and funnel with hole 15, respectively).

Bulk density was measured by accurately filling a 100mL container with the granular MFC product and weighing the contents. The measurement was repeated three times, and the average of the results was calculated.

Table 2:

based on the flow measurements shown in table 2, it can be said that the 90 wt% MFC sample has better flow properties than the sample with the lower solids content. This is most likely due to the higher bulk density of the 90 wt% sample compared to the 55 wt% sample and the 76 wt% sample.

Example 2: redispersion of particulate MFC products

Standard laboratory activation of particulate MFC samples was done via a two-step protocol: 1) wetting step (magnetic stirring, 2 wt% solution, time: 2 hours-overnight, temperature: +23 ℃) where the particulate MFC sample was in contact with water, after which 2) the solution was homogenized with an Ultraturrax high shear mixer (3 x 10 seconds, 1000 rpm).

Redispersion of granular samples with different solids content was investigated. The results are summarized in table 3.

Table 3 viscosity measurements on dried MFC samples after 3h, 6h and 24h wetting steps to redisperse the MFC.

As is clear from table 3, all the dried particulate MFC product could be re-dispersed in water.

Example 3: effect of desiccation on microbial growth

The purpose of this laboratory test was to investigate the preservative effect of drying on microbial growth in microfibrillated cellulose (MFC) samples. MFC samples (2kg) were stored in vacuum without biocide treatment at cold +4 ℃ for 2 weeks. At the start of the test, the MFC sample was divided into 6 individual samples (300 g). To obtain an equal mould spore content in the MFC samples at the start, each sample was spiked with additional mould spores of Aspergillus niger and Penicillium verrucosum (Penicillium verrucosus) with a target mould spore level of about 200 cfu/ml. Spore solutions for spiking were prepared as follows: the frozen pure mold cultures were pre-grown on commercial potato dextrose agar at +25 ℃ for 5 days, after which the mold cells were harvested to commercial ringer's solution (10ml), mixed together and diluted with ringer's solution (1:10) to obtain mold spiked liquid. The liquid was spiked as follows: a total of 6ml of mould liquid was added to 2kg of MFC in small amounts (60X 100. mu.l) to obtain a homogeneous mixture. After spiking, one reference sample was stored without drying, and samples 2-6 were dried (+55 ℃, fluidized bed dryer, Sherwood Model501) for 10min to 30min to obtain MFC samples with different water contents. After drying, the samples (75g) were stored in plastic bags at room temperature. At the beginning and after 3 days, 1 week and 2 weeks storage time, the preservative efficacy of drying was followed by mold (Saborous agar, +25 ℃, 4 days incubation), anaerobic bacteria (Brewer agar, +25 ℃, 3 days incubation) and aerobic bacterial endospore culture (plate count agar, +32 ℃, 2 days). The preservative efficacy of drying was followed by the mold of lower moisture samples #5 and # 6. Samples were pasteurized at +80 ℃ for 20min prior to bacterial endospore assay. Percent water content was calculated by first weighing the suspended solids per kg of MFC (% water content ═ 100% - (dry weight of sample per total weight of sample) × 100%). The results are shown in table 1A (mold), table 1B (anaerobic bacteria) and table 1C (aerobic bacterial endospores).

Table 4.

The results in tables 1A-1C show that microbial growth in the non-preserved reference MFC samples was at a high level within 2 weeks of storage: severe mold growth has been seen in spiked MFC samples within 3 days and the true anaerobic bacterial population as well as aerobic bacterial endospore levels increased significantly within 2 weeks of storage. Thus, the results clearly show the need for microbial control of MFCs where MFCs are stored for several days. Surprisingly, drying MFC to a water content of < 60% showed excellent preservative effect on the flora of the natural bacterial population (1B and 1C). Drying MFC to a water content of < 30% showed excellent preservative effect on both spiked moulds (1A).

Tests indicate that by drying MFC to a moisture content of < 60%, no bactericides are necessarily required. Tests performed indicate that when MFC is dried to a water content of less than 30%, at least at this water content, fungicides are not necessarily required. At least when the moisture content after drying is less than 30%, no biocide (fungicide or bactericide) may be required at all for microbial control. The same may be true for even higher water contents remaining in the MFC product after drying.