Method for producing dispersion-coated fiber substrates

Abstract

The present invention relates to a method for producing a dispersion-coated fibrous substrate, the method comprising: a) forming a fibrous web from one or more fiber suspensions, dehydrating the fiber web, and optionally drying it to obtain a fibrous substrate having a first main surface and a second main surface, wherein at least one of the fiber suspensions is a broken suspension; and b) applying a dispersion coating composition to form a dispersion coating layer on the first main surface, and drying the applied dispersion coating composition to obtain a dispersion-coated fibrous substrate, wherein the broken suspension in a) contains 0.1 to 20% by weight of PHA based on the total solids content of the broken suspension.

Description

[Technical Field]

[0001] This disclosure relates to a method for preparing coated fiber substrates, specifically polyhydroxyalkanoate (PHA) coated paper or cardboard, for use as packaging materials. [Background technology]

[0002] Plastic coatings of fibrous substrates such as paper and cardboard are often used to combine the mechanical properties of the fibrous substrate with the barrier and sealing properties of the plastic film. Even paper or cardboard with relatively small amounts of suitable plastic material can provide the properties necessary to make the paper or cardboard suitable for many demanding applications, such as liquid or food packaging.

[0003] In addition to the liquid barrier inside the packaging, fiber-based packaging products, such as cups or trays, especially those intended for packaging cold products, typically require a condensation layer on the outside of the packaging. This condensation layer prevents condensed liquid from softening the bulky fiber-based substrate. The packaging product also typically includes at least one heat-sealable liquid barrier on the inside.

[0004] In liquid or food packaging paperboard, extruded polyolefin coatings are frequently used as liquid barrier layers, heat seal layers, and adhesives. However, recycling such polymer-coated paperboard is not easy because separating the polymer from the fibers is difficult.

[0005] Prior art has attempted to replace extruded polyolefin coatings with more environmentally friendly and / or more recyclable solutions, but so far there have been no actual successes. In many cases, some, if not all, of the properties of extruded polyolefin coatings are achieved by alternative solutions.

[0006] Dispersion barrier coatings for paper and cardboard are an interesting alternative to extrusion coatings for improving the repulpability and recyclability of barrier-coated fibrous substrates. Dispersion coatings are particularly useful because they can be carried out online in paper machines or cardboard manufacturers. However, many dispersions or emulsions, such as styrene / acrylate emulsions or styrene / butadiene emulsions, are not biodegradable or compostable.

[0007] On the other hand, polyhydroxyalkanoate (PHA)-based dispersion coating barriers are compostable and biodegradable. The challenge with PHA dispersions is finding the right composition to enable good runability in coating machines, good coating holdout, and good barrier performance. Coating holdout and even good barrier performance depend heavily on the roughness of the substrate and the amount of coating, but too much coating negatively impacts recyclability, drying efficiency, and cost. PHA dispersions are usually stabilized by surfactants and / or surfactant polymers, but migration of dispersants and increased foaming tendencies can lead to non-uniformity of barrier performance. Foaming tendencies can cause further problems during recycling, repulping, or defibration of coated webs.

[0008] Many of the aforementioned problems can be avoided by applying PHA using melt extrusion coating. However, unfortunately, extrusion coating of PHA cannot be performed online on a full-scale paper machine or paperboard manufacturer. Furthermore, extrusion coating usually requires a relatively large amount of coating and tends to have inferior adhesion compared to dispersion-coated products. In addition, extruded-coated products are more difficult to repulp than dispersion-coated products.

[0009] Therefore, there is still a need for improved PHA coating solutions to replace conventional plastic coatings, particularly polyolefin coatings, in paper and paperboard-based packaging materials while maintaining acceptable liquid barrier properties. At the same time, there is a need for improved methods for manufacturing PHA-coated paper and paperboard that facilitate the repulping and recycling of the coated paper or paperboard at the mill as well as at the stages before and after consumer use. SUMMARY OF THE INVENTION

[0010] An object of the present disclosure is to provide a polyhydroxyalkanoate (PHA) coating as an alternative to plastic films commonly used as barrier layers for providing liquid barrier properties in paper or paperboard-based packaging materials such as liquid or food packaging board.

[0011] A further object of the present disclosure is to provide an improved method for manufacturing a PHA-dispersion-coated fibrous substrate.

[0012] A further object of the present disclosure is to provide an improved method for manufacturing a PHA-dispersion-coated fibrous substrate that overcomes or improves at least some of the problems associated with conventional PHA coating methods.

[0013] A further object of the present disclosure is to provide an improved method for manufacturing a PHA-dispersion-coated fibrous substrate that enables efficient recycling of PHA coating breaks. In particular, an object of the present disclosure is to provide a method for manufacturing a PHA-dispersion-coated fibrous substrate that enables efficient recycling of PHA coating breaks without causing excessive foaming or non-uniform barrier properties in the coated substrate.

[0014] The above objects, as well as other objects realized by those skilled in the art in light of the present disclosure, are achieved by various aspects of the present disclosure.

[0015] The present invention is based on the understanding that by using a relatively large amount of low molecular weight polyol as a dispersant for PHA particles, many problems related to PHA dispersion coatings on fibrous substrates, particularly related to the recycling of PHA coating broke, can be overcome or improved. Problems that can be overcome or improved include excessive foaming during repulping and the formation of large PHA flakes, which can lead to a decrease in yield in the recycling process. Surprisingly, it has been confirmed that a large amount of low molecular weight polyol does not adversely affect the barrier properties of the PHA coating. Since the dispersant is expected to reduce the barrier properties of the PHA coating, typically the dispersant is used in an amount of less than 1 wt% based on the dry weight of the dispersion coating composition. Another surprising finding is that the amount of low molecular weight polyol remaining in the recycled pulp after repulping does not adversely affect the mechanical properties of the new paper or board formed using the recycled pulp.

[0016] According to a first aspect shown herein, a method for manufacturing a dispersion-coated fibrous substrate, the method comprising: a) forming a fibrous web from one or more fibrous suspensions, dewatering the fibrous web, and optionally drying to obtain a fibrous substrate having a first major surface and a second major surface, wherein at least one of the fibrous suspensions is a broke suspension, obtaining a fibrous substrate; b) forming a dispersion coating layer on the first major surface by applying a dispersion coating composition and drying the applied dispersion coating composition to obtain a dispersion-coated fibrous substrate, wherein the dispersion coating composition comprises in a liquid medium 50 to 99 wt% of dispersed polyhydroxyalkanoate (PHA) particles based on the total solids of the dispersion coating composition, and 1 to 50 wt% of dissolved low molecular weight polyol dispersant based on the total solids of the dispersion coating composition, A process to obtain a dispersion-coated fiber substrate in which the total solid content of the dispersion coating composition is in the range of 20 to 80% by weight. Includes, a) A method is provided in which the Broke suspension contains 0.1 to 20% by weight of PHA based on the total solids content of the Broke suspension.

[0017] The fibrous web and fibrous substrate (also referred to herein as “substrate”) formed in step a) are preferably formed mainly from pulp of wood or other fibrous material. In some embodiments, the fibrous substrate is paper or cardboard, preferably cardboard.

[0018] Paper generally refers to a material manufactured in sheets or rolls from pulp of wood or other fibrous materials, including cellulose fibers, and is used, for example, for writing, drawing, printing, or as packaging material. Paper can be bleached or unbleached, depending on the requirements of its end use, and can be manufactured in various thicknesses.

[0019] Cardboard generally refers to strong cardboard or corrugated cardboard containing cellulose fibers, used, for example, as a flat substrate, tray, box, and / or other types of packaging. Depending on the requirements of the end use, cardboard can be either bleached or unbleached and can be manufactured in various thicknesses.

[0020] While different configurations for carrying out the steps of the present invention may be considered by those skilled in the art, the present invention is advantageously carried out in a papermaking machine, more preferably a Ford Liner papermaking machine. A papermaking machine (or papermaking machine) is an industrial machine used in the pulp and paper industry to produce paper or cardboard at high speed and in large quantities. Modern papermaking machines are typically based on the principle of a Ford Liner machine, which uses a moving woven mesh, so-called "wire," to produce a continuously moving fiber web by filtering and dewatering fibrous material held in one or more fiber suspensions. One or more fiber suspensions are applied to the wire using one or more headboxes. The function of the headboxes is to dopate and distribute the fiber suspension uniformly across the width of the wire. The fiber web can be formed as a single-layer or multi-layer structure using the same or different fiber suspensions in different layers. Dewatering of the fiber web on the wire can be carried out using methods and apparatus known in the art, including, but not limited to, table rolls and foils, suction boxes, frictionless dewatering, and ultrasonic-assisted dewatering. The dehydrated fiber web is then typically dried within the machine to produce a fibrous substrate. Drying may include, for example, passing the fiber web around a series of heated drying cylinders.

[0021] In the method of the present invention, a fiber web is formed from one or more fiber suspensions, at least one of which is a broken suspension, and the broken suspension contains 0.1 to 20% by weight of PHA based on the total solids content of the broken suspension.

[0022] As used herein, the term “broke” refers to partially or completely manufactured paper or cardboard that is discarded from the manufacturing, conversion, or finishing process of paper or cardboard. Broke may be uncoated broken, i.e., broken formed before the coating of the paper or cardboard, or coated broken, i.e., broken formed after the coating of the paper or cardboard, or a mixture of uncoated and coated broken. Broke is typically collected, fed to a repulper, pulped in an aqueous medium, and optionally blended with other fiber sources to obtain a broken suspension useful for papermaking.

[0023] As used herein, the term “broken suspension” generally refers to a fibrous suspension in which at least a portion of the fibrous components are derived from broken fibers. In some embodiments, all of the fibrous components of the broken suspension are derived from broken fibers. In some embodiments, at least 1% by weight, preferably at least 5% by weight, of the fibrous components of the broken suspension are derived from broken fibers. In some embodiments, at least 10% by weight, preferably at least 20% by weight, at least 30% by weight, at least 40% by weight, at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, or at least 90% by weight, of the fibrous components of the broken suspension are derived from broken fibers. In some embodiments, 1 to 50% by weight, preferably 1 to 40% by weight, more preferably 1 to 30% by weight, of the fibrous components of the broken suspension are derived from broken fibers. In some embodiments, 5 to 50% by weight, preferably 5 to 40% by weight, more preferably 5 to 30% by weight, of the fibrous components of the broken suspension are derived from broken fibers. In some embodiments, 10–50% by weight, preferably 10–40% by weight, and more preferably 10–30% by weight of the fibrous component of the broken suspension is derived from broken pulp. The remaining portion of the fibrous component of the broken suspension may consist of any other type of pulp fiber, such as bleached and / or unbleached kraft pulp, sulfite pulp, dissolved pulp, thermomechanical pulp (TMP), chemothermetic pulp (CTMP), high-temperature CTMP (HT-CTMP), pressure-ground wood pulp (PGW), recycled pulp, such as waste before and after consumer use, and / or fibers from mixtures thereof.

[0024] In some embodiments, the fiber web formed in a) is a single-layer fiber web formed entirely from a Broke suspension.

[0025] In some embodiments, the fiber web formed in a) is a multilayer fiber web formed entirely from Broke suspension.

[0026] In some embodiments, the fiber web formed in a) is a single-layer fiber web formed from a mixture of a Broke suspension and at least one other fiber suspension.

[0027] In some embodiments, the fiber web formed in a) is a multilayer fiber web formed from a Broke suspension and at least one other fiber suspension.

[0028] In some embodiments, the fiber web formed in a) is a multilayer fiber web in which at least one layer is formed from a broken suspension and at least one layer is formed from another fiber suspension.

[0029] In some embodiments, the fiber web formed in a) is a multilayer fiber web comprising an upper layer, an intermediate layer, and a lower layer, wherein the intermediate layer is formed from a Broke suspension, and the upper and lower layers are formed from one or more other fiber suspensions.

[0030] The fiber components of other fiber suspensions may consist of any other type of pulp fiber, other than broken suspension, such as bleached and / or unbleached kraft pulp, sulfite pulp, dissolved pulp, thermomechanical pulp (TMP), chemothermetic pulp (CTMP), high-temperature CTMP (HT-CTMP), pressure-ground wood pulp (PGW), broken, recycled pulp, waste before and after consumer use, and / or mixtures thereof.

[0031] In some embodiments, the basis weight of the fibrous substrate is 20 to 800 g / m². 2 It is within the range. In some embodiments, the fibrous substrate is at least 100 g / m 2 It has a basis weight of . In some embodiments, the fibrous base material has a basis weight of at least 150 g / m². 2 200g / m 2 250g / m 2 300g / m 2 350g / m 2 , or 400g / m 2It has a basis weight. The basis weight of the fibrous substrate is preferably less than 1000 g / m 2 ², less than 800 g / m 2 ², or less than 600 g / m 2 ². Unless otherwise specified, the basis weight is determined according to standard ISO 536.

[0032] The fibrous substrate formed in step a) may be subjected to surface sizing or impregnation treatment. In some embodiments, the fibrous substrate may be surface sized or impregnated on one or both sides with a surface sizing composition preferably containing a starch derivative, a cellulose derivative, or polyvinyl alcohol (PVOH) or a combination thereof. The starch derivative may be, for example, lightly modified, and examples include oxidized starch or cationized starch. The cellulose derivative may be sodium carboxymethyl cellulose having a degree of substitution in the range of more than 0.4, for example, 0.5 to 1.5. PVOH may be completely or partially hydrolyzed. The surface sizing composition may also contain a hydrophobic sizing agent such as alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), or rosin sizing agent. The fibrous substrate is preferably surface sized or impregnated on the first major surface to which the dispersion coating is applied. The surface sizing or impregnation treatment can provide a more uniform and less water-absorbent surface for the dispersion coating composition. The surface sizing or impregnation treatment can also promote the release of the PHA coating structure from the fibrous substrate during repulping.

[0033] In some embodiments, the basis weight of the surface sizing composition is 0.2 to 10 g / m 2 ² per side, preferably 0.4 to 8 g / m 2 ², more preferably 0.8 to 5 g / m 2 ², based on the dry weight.

[0034] The fibrous substrate itself may have relatively high permeability to liquids such as water, oil, and grease, water vapor, and gases such as oxygen, air, and carbon dioxide, prior to PHA coating. In some embodiments, the fibrous substrate has a density of at least 200 g / m², as measured according to standard ASTM F1249-20 at 50% relative humidity and 23°C. 2 It has a water vapor transmission rate (WVTR) of 100 g / m² / 24h. In some embodiments, the fibrous substrate is measured according to standard ISO 535 and has a WVTR of 100 g / m². 2 Less than 80 g / m², preferably 80 g / m² 2 Less than 60g / m² 2 Less than 40g / m² 2 It has a COBB60 value of less than .

[0035] Prior to PHA coating, the fibrous substrate itself preferably has an L&W (15°) bending resistance of at least 145 mN (MD) as determined according to ISO 2493-1.

[0036] The broken suspension in step a) is preferably formed from fibers obtained at least partially from recycled PHA dispersion-coated broken fibers.

[0037] In some embodiments, 1 to 100% by weight of the fibers in the broken suspension of a) are derived from PHA dispersion-coated broken fibers recycled from a method for producing a dispersion-coated fiber substrate. In some embodiments, 5 to 100% by weight, more preferably 5 to 50% by weight or 10 to 20% by weight of the fibers in the broken suspension of a) are derived from PHA dispersion-coated broken fibers recycled from a method for producing a dispersion-coated fiber substrate.

[0038] The broken suspension of step a) is preferably formed, at least partially, from fibers obtained from recycled PHA dispersion-coated brokens. As a result, the broken suspension of a) contains 0.1 to 20% by weight of PHA based on the total solids content of the broken suspension. In some embodiments, the broken suspension of a) contains 0.1 to 15% by weight, preferably 0.1 to 10% by weight, and more preferably 0.1 to 5% by weight of PHA based on the total solids content of the broken suspension. In some embodiments, the PHA in the broken suspension of a) is derived from PHA dispersion-coated brokens recycled from a method for producing dispersion-coated fiber-based substrates.

[0039] Since the Broke suspension in a) contains PHA, the fibrous substrate obtained in a) also contains PHA. In some embodiments, the fibrous substrate obtained in a) contains 0.1 to 20% by weight of PHA based on the total solids content of the fibrous substrate. In some embodiments, the fibrous substrate obtained in a) contains 0.1 to 15% by weight, preferably 0.1 to 10% by weight, and more preferably 0.1 to 5% by weight of PHA based on the total solids content of the fibrous substrate.

[0040] Since Broke suspensions are often used in combination with other fiber suspensions, the fibrous substrate obtained in a) may contain significantly less PHA. Therefore, in some embodiments, the fibrous substrate obtained in a) contains 0.1 to 5% by weight of PHA based on the total solids content of the fibrous substrate. In some embodiments, the fibrous substrate obtained in a) contains 0.1 to 5% by weight, preferably 0.1 to 2.5% by weight, and more preferably 0.1 to 2% by weight of PHA based on the total solids content of the fibrous substrate.

[0041] If the fibrous substrate obtained in a) is a multilayer fibrous substrate, at least one of the layers may contain a higher PHA content, while the other layer may contain a lower PHA content or no PHA at all. Therefore, in some embodiments where the fibrous substrate obtained in a) is a multilayer fibrous substrate, at least one of the layers contains 0.1 to 20% by weight, for example, 0.1 to 15% by weight, 0.1 to 10% by weight, or 0.1 to 5% by weight of PHA based on the total solid content of the layer.

[0042] In some embodiments, the method includes recycling fibers from PHA dispersion-coated brokens in a) broken suspension. PHA dispersion-coated brokens refer to partially or completely manufactured PHA dispersion-coated fiber substrates.

[0043] In some embodiments, the method includes recycling fibers from PHA dispersion-coated brokes formed in the method of the present invention for producing a broke suspension dispersion-coated fiber substrate of a).

[0044] Unlike the recycling of conventional mineral-coated paper and cardboard, the recycling of fibers from PHA-dispersed coated brokens often results in the PHA coating peeling off as large flakes when the PHA-dispersed coated brokens are processed in a pulper. In this invention, by using a relatively large amount of low molecular weight polyol as a dispersant for the PHA particles, the amount of flakes formed during pulping is reduced. Since some PHA flakes and PHA aggregates can still form during pulping, the recycling of PHA-dispersed coated brokens preferably includes at least one agglomeration step and / or screening step to remove PHA flakes and PHA aggregates.

[0045] In some embodiments, recycling is i) Pulping a PHA dispersion coated broke in an aqueous medium, ii) The pulped PHA dispersion coated broken is subjected to disintegration and / or screening to remove PHA flakes and PHA aggregates.

[0046] The pulping temperature is preferably in the range of 30 to 95°C, and more preferably in the range of 50 to 80°C. Sodium hydroxide is preferably added to adjust the pH to a range of greater than 7.5, preferably greater than 8, and more preferably in the range of 8.5 to 11. The consistency during pulping can be low (1 to 6 wt%), medium (8 to 20 wt%), or high (>20%). Medium or high consistency is preferred because it provides both better pulping and better energy efficiency. After pulping the broken, the pulped PHA dispersion coated broken is subjected to disintegration and / or screening to remove PHA flakes and PHA aggregates. Disintegration can be carried out, for example, in a disc or conical disintegration unit. Screening may be performed using, for example, at least one first blow screening unit with slots (slot width < 0.3 mm, preferably 0.1 to 0.3 mm) or holes (hole diameter < 4 mm, preferably 1 to 3 mm), and at least one second blow screening unit with slots (slot width < 0.2 mm, preferably 0.1 to 0.2 mm) or holes (hole diameter < 1 mm, preferably 0.1 to 1 mm). Unsuitable material from the deburring and / or screening unit can be reintroduced into the screening or deburring unit. This recycling method ensures good quality of the recycled fibers and prevents large aggregates from being reused.

[0047] The drying-pulping-disintegration-screening operations in recycling always carry the risk of affecting the fiber profile and composition of the fiber suspension, thereby beginning to affect sheet properties such as runnability at the wet end, including drainage behavior, as well as the bulkiness, roughness, stiffness, and strength characteristics of the resulting fibrous substrate. The goal of recycling is to obtain large quantities of good quality recycled fiber conformers. The use of large amounts of low molecular weight polyols as dispersants helps to ensure this. High dispersant content can adversely affect pulping and sheet properties. However, stock quality (SQD) measurements comparing sheets prepared using only fresh CTMP with sheets prepared using only recycled PHA dispersion coated brokens, and sheets prepared using a mixture of fresh CTMP and recycled PHA dispersion coated brokens have shown this is not the case. SQD is calculated according to the following formula, where the process sample sheet is a sheet prepared using only recycled PHA dispersion coated brokens, or a sheet prepared using a mixture of recycled PHA dispersion coated brokens and fresh CTMP, and the laboratory sample sheet is a sheet prepared using only fresh CTMP. TIFF2026511011000001.tif16170

[0048] In some embodiments, the SQD is at least 60%, preferably at least 70%, more preferably at least 80%, for example, in the range of 85-150%.

[0049] a) The fibrous substrate obtained in a) has a dispersion coating layer containing polyhydroxyalkanoate (PHA) particles coated on its first main surface. The dispersion coating layer is formed by applying the dispersion coating composition onto the first main surface and drying the applied dispersion coating composition to obtain a dispersion coated fibrous substrate, and the dispersion coating composition is in a liquid medium, Dispersed polyhydroxyalkanoate (PHA) particles in an amount of 50-99% by weight relative to the total solid content of the dispersion coating composition, and The dispersion coating composition contains 1 to 50% by weight of a dissolved low molecular weight polyol dispersant relative to the total solid content. The total solid content of the dispersion coating composition is in the range of 20 to 80% by weight.

[0050] PHA particles are preferably the main component of the dispersion coating composition based on the dry weight of the composition. In some embodiments, the dispersion coating composition contains at least 50% by weight, at least 65% by weight, at least 70% by weight, or at least 90% by weight of PHA particles based on the total solids content of the dispersion coating composition. In some embodiments, the dispersion coating composition contains 70-99% by weight, preferably 90-99% by weight, of PHA particles based on the total solids content of the dispersion coating composition. In some embodiments, the dispersion coating composition contains 50-97% by weight, 50-95% by weight, 50-92.5% by weight, 50-90% by weight, 50-87.5% by weight, or 50-85% by weight of PHA particles based on the total solids content of the dispersion coating composition. In some embodiments, the dispersion coating composition contains 65-97% by weight, 65-95% by weight, 65-92.5% by weight, 65-90% by weight, 65-87.5% by weight, or 65-85% by weight of PHA particles based on the total solids content of the dispersion coating composition. In some embodiments, the dispersion coating composition contains 70-97% by weight, 70-95% by weight, 70-92.5% by weight, 70-90% by weight, 70-87.5% by weight, or 70-85% by weight of PHA particles based on the total solids content of the dispersion coating composition. In some embodiments, the dispersion coating composition contains 90-97% by weight, 90-95% by weight, or 90-92.5% by weight of PHA particles based on the total solids content of the dispersion coating composition.

[0051] The particle size distribution of PHA particles can be multimodal or unimodal. In some embodiments, PHA particles have a unimodal or bimodal particle size distribution. In some embodiments, PHA particles have a unimodal particle size distribution.

[0052] In some embodiments, the PHA particles have a median particle size (D50) of less than 15 μm, preferably less than 12 μm, more preferably in the range of 0.5 to 11 μm, or in the range of 0.8 to 8 μm.

[0053] In some embodiments, the dispersion coating composition does not contain, or substantially does not contain, particles or particle aggregates having particle sizes greater than 50 μm, greater than 20 μm, or greater than 15 μm.

[0054] Unless otherwise specified, all particle sizes and particle size distributions herein are determined by laser diffraction using a Mastersizer 3000 in accordance with ISO 13320:2009.

[0055] In some embodiments, the PHA particles contain 70 to 99.9% by weight, preferably 90 to 99.9% by weight, of PHA based on the dry weight of the PHA particles.

[0056] In some embodiments, PHA is selected from the group consisting of poly(3-hydroxyoctanoate) (PHO), poly(3-hydroxydecanoate) (PHD), poly(3-hydroxyhexanoate) (PHH), and poly(3-hydroxyvalerate) (PHV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxyoctanoate-co-3-hydroxyhexanoate) (PHOHH), poly(3-hydroxyoctanoate-co-3-hydroxydecanoate) (PHOHD), and poly(3-hydroxyoctanoate-co-3-hydroxydodecanoate) (PHDHDD), or combinations thereof. Those skilled in the art will understand that PHAs suitable for use in dispersion coating compositions are not limited to those listed herein.

[0057] In some embodiments, PHA is a PHA copolymer.

[0058] In some embodiments, the PHA is selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxyoctanoate-co-3-hydroxyhexanoate) (PHOHH), poly(3-hydroxyoctanoate-co-3-hydroxydecanoate) (PHOHD), and poly(3-hydroxyoctanoate-co-3-hydroxydodecanoate) (PHDHDD), or combinations thereof. Those skilled in the art will understand that PHA copolymers suitable for use in dispersion coating compositions are not limited to those listed herein.

[0059] In some embodiments, the PHA is a medium-chain PHA, preferably a PHA having 6 to 14 carbon atoms per monomer unit.

[0060] The type of PHA suitable for use in dispersion coating compositions can be characterized by its melting point. In some embodiments, the PHA has a melting point in the range of 100 to 170°C, preferably in the range of 120 to 160°C. Unless otherwise specified, the melting points referred to herein are determined by differential scanning calorimetry according to standard ASTM D3418.

[0061] The dispersion coating composition of the present invention contains 1 to 50% by weight of a low molecular weight polyol dispersant based on the total solids content of the dispersion coating composition. Dispersants are typically low molecular weight polymers used to improve the colloidal stability of dispersions and reduce viscosity (e.g., by reducing floc formation). Dispersants are not typically used to improve the barrier properties of coatings. In fact, many dispersants, especially at higher concentrations, are expected to migrate and reduce the barrier properties of barrier coatings.

[0062] In some embodiments, the dispersion coating composition contains 3 to 35% by weight, more preferably 5 to 30% by weight, of a low molecular weight polyol dispersant based on the total solids content of the dispersion coating composition. In some embodiments, the dispersion coating composition contains 7.5 to 35% by weight, preferably 10 to 35% by weight, more preferably 12.5 to 35% by weight, and more preferably 15 to 35% by weight, of a low molecular weight polyol dispersant based on the total solids content of the dispersion coating composition. In some embodiments, the dispersion coating composition contains 7.5 to 30% by weight, preferably 10 to 30% by weight, more preferably 12.5 to 30% by weight, and more preferably 15 to 30% by weight, of a low molecular weight polyol dispersant based on the total solids content of the dispersion coating composition. In some embodiments, the dispersion coating composition contains 7.5 to 25% by weight, preferably 10 to 25% by weight, more preferably 12.5 to 25% by weight, and more preferably 15 to 25% by weight, of a low molecular weight polyol dispersant based on the total solids content of the dispersion coating composition.

[0063] In some embodiments, the dispersion coating composition comprises 3 to 35% by weight of a low molecular weight polyol dispersant and 65 to 97% by weight of PHA particles, or 5 to 30% by weight of a low molecular weight polyol dispersant and 70 to 95% by weight of PHA particles, based on the total solids content of the dispersion coating composition. In some embodiments, the dispersion coating composition comprises 7.5 to 30% by weight of a low molecular weight polyol dispersant and 70 to 92.5% by weight of PHA particles, or 10 to 30% by weight of a low molecular weight polyol dispersant and 70 to 90% by weight of PHA particles, or 12.5 to 30% by weight of a low molecular weight polyol dispersant and 70 to 87.5% by weight of PHA particles, or 15 to 30% by weight of a low molecular weight polyol dispersant and 70 to 85% by weight of PHA particles, based on the total solids content of the dispersion coating composition.

[0064] In some embodiments, the low molecular weight polyol dispersant has a molecular weight in the range of 50 to 2000 g / mol, preferably in the range of 50 to 1500 g / mol, more preferably in the range of 50 to 1000 g / mol or in the range of 50 to 500 g / mol.

[0065] In some embodiments, the low molecular weight polyol dispersant is selected from the group consisting of low molecular weight polysaccharides and sugar alcohols, as well as combinations thereof.

[0066] In some embodiments, the low molecular weight polyol dispersant is selected from the group consisting of low molecular weight polysaccharides having a degree of polymerization (DP) in the range of 2 to 100, preferably in the range of 2 to 50. In some embodiments, the low molecular weight polyol dispersant is selected from the group consisting of low molecular weight polysaccharides having a degree of polymerization (DP) in the range of 2 to 12. The low molecular weight polysaccharides may be charged, uncharged, amphoteric, or a combination thereof. The low molecular weight polysaccharides may be linear or branched.

[0067] In some embodiments, the low molecular weight polyol dispersant is a sugar alcohol, preferably selected from the group consisting of sorbitol, maltitol, xylitol, mannitol, and glycerol, and combinations thereof. In some embodiments, the low molecular weight polyol dispersant is selected from the group consisting of sorbitol, maltitol, xylitol, mannitol, and combinations thereof. In some embodiments, the low molecular weight polyol dispersant is sorbitol.

[0068] In some embodiments, the dispersion coating composition further comprises 0.01 to 15% by weight, preferably 0.01 to 10% by weight, and more preferably 0.1 to 5% by weight, of a rheological modifier based on the total solids content of the dispersion coating composition. The rheological modifier is used to adjust the viscosity and water retention of the dispersion coating composition to suit application by preferred application methods.

[0069] In some embodiments, the rheological modifier includes a polymer selected from the group consisting of polysaccharides, polysaccharide derivatives, polypeptides, polypeptide derivatives, or combinations thereof.

[0070] In some embodiments, the dispersion coating composition further comprises 1 to 30% by weight of filler particles based on the total solids content of the dispersion coating composition. Too many filler particles can lead to cracking and reduced barrier properties. The amount of filler particles is preferably 5 to 25% by weight, more preferably 5 to 15% by weight, relative to the total solids content of the dispersion coating composition.

[0071] In some embodiments, the filler particles are selected from the group consisting of clay (such as kaolin or calcined kaolin), talcam, CaCO3 (such as PCC or GCC), TiO2, Al2O3, SiO2, bentonite, fibers, phyllosilicates, or combinations thereof. The filler particles are preferably high aspect ratio filler particles, for example, flake particles having a median particle size (D90) of less than 2 μm.

[0072] In some embodiments, the dispersion coating composition comprises, based on the total solids content of the dispersion coating composition, at least 50% by weight of polyhydroxyalkanoate (PHA) particles, an amount of low molecular weight polyol dispersant disclosed herein, optionally an amount of rheological modifier disclosed herein, and optionally an amount of filler particles disclosed herein. In some embodiments, the dispersion coating composition comprises, based on the total solids content of the dispersion coating composition, at least 70% by weight of polyhydroxyalkanoate (PHA) particles, 7.5 to 30% by weight of low molecular weight polyol dispersant, 0.1 to 5% by weight of rheological modifier, and optionally 5 to 25% by weight of filler particles.

[0073] In some embodiments, the dispersion coating composition may also include further additives such as lubricants, humectants or softeners, sizing agents, dehydration accelerators, slime inhibitors, wetting strength agents, pH adjusters, defoamers, crosslinking agents, biocides, preservatives, and / or colorants.

[0074] In some embodiments, the dispersion coating composition does not contain any foaming agent, such as a nonpolymer or polymer surfactant. In some embodiments, the dispersion coating composition contains less than 0.5% by weight, preferably less than 0.1% by weight, and more preferably less than 0.01% by weight, an added foaming agent, such as a nonpolymer or polymer surfactant.

[0075] In some embodiments, the dispersion coating composition is degassed. Low molecular weight polyol dispersants are advantageous in this respect because molecular weight polyol dispersants are less likely to trap air bubbles than high molecular weight dispersants. Therefore, in some embodiments, the dispersion coating composition is preferably free of or substantially free of air and other gas bubbles.

[0076] In some embodiments, the dispersion coating composition has a total solids content in the range of 30 to 70% by weight, preferably in the range of 40 to 60% by weight.

[0077] In some embodiments, the dispersion coating composition has a viscosity in the range of 50 to 4000 mPas, preferably in the range of 250 to 3500 mPas, determined according to SCAN-P50:84 using a Brookfield viscometer equipped with an LV-4 spindle at a rotational speed of 100 rpm.

[0078] In some embodiments, the dispersion coating composition is determined according to TAPPI T701pm-0, at 250 g / m². 2 Less than 200 g / m², preferably 200 g / m² 2 Less than 50-150 g / m² is preferable. 2 It has an ÅAGWR water retention value (Åbo Akademi water retention value) in the range of [value].

[0079] The liquid medium may include water, an organic solvent, or a mixture of water and an organic solvent. In some embodiments, the liquid medium is water.

[0080] The dispersion coating composition used in step b) of this specification enables improved production of PHA-coated fiber-based substrates.

[0081] The dispersion coating layer is preferably formed by a liquid film coating process, in which the dispersion coating composition is applied to the substrate, spread into a thin, uniform layer, and then dried.

[0082] In some embodiments, the dispersion coating composition is 5-40 g / m² based on dry weight. 2 In the range of 5-30 g / m², preferably 5-30 g / m² 2 In the range of 5-20 g / m², more preferably 5-20 g / m² 2It is applied in basis weights within the range of [range]. The thickness of the wet dispersion coating composition when applied to a substrate is typically in the range of 20 to 100 μm, preferably in the range of 20 to 50 μm. Therefore, it is preferable that the dispersion coating composition does not contain particles or particle aggregates larger than 20 to 50 μm. Thus, in some embodiments, the dispersion coating composition does not contain, or substantially does not contain, particles or particle aggregates having particle sizes greater than 50 μm, greater than 20 μm, or greater than 15 μm.

[0083] In some embodiments, a binder layer may be applied between the fibrous substrate and the dispersion coating layer to improve adhesion between the fibrous substrate and the dispersion coating layer. The binder layer preferably contains an adhesive polymer that can further improve adhesion between the substrate and the dispersion coating layer. The binder layer may contain, for example, PHA having a lower melting point than the PHA of the dispersion coating layer, for example, in the range of 60 to 120°C, polyvinyl alcohol (PVOH), or any other bio-derived and / or biodegradable and compostable polymer that can further improve adhesion between the substrate and the dispersion coating layer.

[0084] In some embodiments, the dispersion coating composition is applied by a non-contact application method. In some embodiments, the dispersion coating composition is applied by an application method selected from the group consisting of roller coating, spray coating, curtain, blade coating, slot coating, dipping coating, gravure roll coating, reverse direct gravure coating, rod coating, soft tip blade coating, short dwell, and soft tip rod coating, and combinations thereof. In some embodiments, the dispersion coating composition is applied by blade coating or rod coating. The dispersion coating composition may be applied directly to a fibrous substrate or indirectly, for example, via a transfer roll or belt.

[0085] To minimize the risk of pinholes in the dispersion coating layer, the dispersion coating layer may be formed by applying the dispersion coating composition in two or more steps, with pre-drying between steps. In such embodiments, the dispersion coating composition in each step is 5 to 10 g / m² based on dry weight. 2 It can be applied in basis weights within the range of [range]. In some embodiments, the dispersion coating composition applied in the first step may be different from the dispersion coating composition applied in the second step. In some embodiments, the PHA particles in the dispersion coating composition applied in the second step have a median particle size smaller than the median particle size of the particles in the dispersion coating composition applied in the first step. In some embodiments, the median particle size of the PHA in the second step is at least 10% smaller, preferably at least 20% smaller, and more preferably at least 30% smaller than the median particle size of the PHA in the second step.

[0086] In some embodiments, drying includes subjecting the dispersion coating composition to heating. In some embodiments, drying includes subjecting the dispersion coating composition to at least one non-contact drying step, such as hot air with infrared radiation, electron beam radiation, ultraviolet radiation, microwave radiation, impingement, or a combination thereof. Optionally, the dispersion coating composition is then subjected to at least one further drying step, which may be a hot air drying step or a contact drying step, such as heat conduction drying using a heating belt or heating cylinder.

[0087] In some embodiments, the dry dispersion coating layer is 5-40 g / m². 2 In the range of 5-30 g / m², preferably 5-30 g / m² 2 In the range of 5-20 g / m², more preferably 5-20 g / m² 2 It has a basis weight in the range of [value]. In some embodiments, the dry dispersion coating layer has a thickness in the range of 8 to 20 μm.

[0088] In some embodiments, the method is c) Further comprising forming a heat-fusible liquid barrier layer on the second main surface.

[0089] In some embodiments, the method is c) Forming a dispersion coating layer on a second main surface, wherein the dispersion coating layer is Based on the total solid content of the dispersion coating layer, 50-99% by weight of polyhydroxyalkanoate (PHA) particles, and 1 to 50% by weight of low molecular weight polyol dispersant based on the total solid content of the dispersion coating layer The further step is to form a dispersion coating layer containing on a second main surface.

[0090] The dispersion coating layer on the second main surface may be further defined as the dispersion coating layer on the first main surface. The dispersion coating layer on the second main surface may be identical to or different from the dispersion coating layer on the first main surface.

[0091] Some non-limiting examples of possible embodiments of dispersion-coated fiber substrates are shown below: PHA dispersion coating / cardboard / PHA dispersion coating PHA dispersion coating / paperboard / binding layer / PHA dispersion coating PHA dispersion coating / paperboard / binding layer / barrier paper or barrier film / PHA dispersion coating

[0092] In some embodiments, the dispersion-coated fiber substrate was measured at 50% relative humidity and 23°C according to standard ASTM F1249-20 to 25 g / m². 2 Less than 24 hours, preferably 20 g / m² 2 Less than 24 hours, more preferably 17 g / m² 2 It has a water vapor transmission rate (WVTR) of less than / 24h.

[0093] In some embodiments, the dispersion-coated first main surface of the dispersion-coated fibrous substrate is measured according to standard SCAN-P 12:64 to 25 g / m². 2 Less than 20 g / m², preferably 20 g / m² 2 Less than 15 g / m², more preferably 15 g / m² 2 It has a COBB600 value of less than 600.

[0094] In some embodiments, the dispersion-coated first main surface of the dispersion-coated fibrous substrate has a KIT value of at least 5, preferably at least 10.

[0095] In some embodiments, the dispersion-coated first main surface of the dispersion-coated fibrous substrate does not contain pinholes. The number of pinholes can be determined, for example, according to standard EN13676:2001. The substrate film preferably has 10 pinholes / m². 2 Less than 8 pieces / m 2 Less than, more preferably 2 pieces / m 2 Includes pinholes smaller than 1m. 2 The number of pinholes per unit can be measured by optical inspection, for example, according to standard EN13676:2001.

[0096] Dispersion-coated fibrous substrates can be recycled into other paper products using common repulping techniques. During repulping, the cellulose fibers of the fibrous substrate are separated from a non-repulpable fraction called the impurity. The impurity may include, for example, aggregated fibers and solid foreign matter that need to be removed for disposal or incineration. In some embodiments, the dispersion-coated fibrous substrate has repulpability characterized by an impurity rate of less than 20%, preferably less than 10%, and more preferably less than 5%, as determined according to the PTS RH 021 / 97 test method for Category II products. By using a relatively large amount of low molecular weight polyol as a dispersant for the PHA particles, the dispersion-coated fibrous substrate exhibits very good repulpability. Therefore, the dispersion-coated fibrous substrate can be referred to as a repulpable material.

[0097] Generally, products, polymers, materials, layers, and processes are described using the term "contains" various components or processes, but products, polymers, materials, layers, and processes can also "essentially consist of" or "be made of" various components and processes.

[0098] Although the present invention has been described with reference to various exemplary embodiments, it will be understood by those skilled in the art that various modifications can be made and elements can be replaced with equivalents without departing from the scope of the invention. Furthermore, many modifications can be made to adapt the teachings of the invention to specific situations or materials without departing from the essential scope of the invention. Thus, the present invention is not limited to the specific embodiments disclosed as the best mode intended to carry out the invention, and the invention is intended to include all embodiments that fall within the scope of the appended claims. [Examples]

[0099] Starting material - PHA dispersion coated paperboard The following examples demonstrate the repulping and recycling of PHA dispersion-coated fiberboard.

[0100] As a starting material, a three-ply base cardboard was used, having an upper and lower layer formed from kraft pulp and an intermediate layer formed from a mixture of CTMP and kraft pulp. One side of the three-ply base cardboard was coated with a PHA dispersion coating selected from PHA1 and PHA2.

[0101] PHA1 was a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) dispersion used as received, containing high levels of surfactants and / or stabilizers and wetting agents, forming a stabilized dispersion. On the other hand, the high levels of additives increased the tendency to foam. Foaming was reduced by using an antifoaming agent. The barrier properties of the PHA1 coated paperboard were good, with COBB600 <20 g / m². 2And the KIT was at least 7.

[0102] PHA2 was a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) dispersion stabilized with sorbitol, a polysaccharide-based rheological modifier, and an antifoaming agent. Although the sorbitol content was relatively high (17.5% by weight), no foaming occurred during coating. The PHA2-coated paperboard exhibited good barrier properties, with COBB600 being <40 g / m². 2 KIT is 12, WVTR is 17g / m 2 It was / day.

[0103] The PHA dispersion coating was performed by coating with PHA1 to a total coating amount of 20 gsm and then drying at a temperature below 150°C, or by coating with PHA2 to a total coating amount of 20 gsm and then drying at a temperature of 110°C.

[0104] The base sheet for physical testing was prepared according to ISO 5269-1.

[0105] Repulping method Repulping was performed according to the PTS RH 021 / 97 test method for Category II products, at pH 7-8, 3% consistency, 40°C, and 150 gsm.

[0106] Example 1 (Comparative Example) - Disintegration of 100% by weight PHA1 dispersion coated paperboard. Paperboard coated with 100% by weight PHA1 dispersion (DCB) was defibrated according to the repulping method described above. Despite the addition of an antifoaming agent to the dispersion, the defibrated pulp produced a large amount of foam. Furthermore, due to the high content of large PHA flakes, defibration was not possible.

[0107] Example 2 - Fiber dissolution of 10 wt% PHA2 dispersion coated paperboard A mixture of 10% by weight PHA2 dispersion coated paperboard (DCB) and 90% by weight CTMP pulp was defibrated according to the repulping method described above. As determined according to the PTS RH 021 / 97 test method for Category II products, the defibrated pulp was homogeneous and free of defects. No issues of foaming or high air content were observed.

[0108] Example 3 - Disintegration of 100% by weight PHA2 dispersion coated paperboard. Paperboard coated with 100% by weight of PHA2 dispersion (DCB) was defibrated according to the repulping method described above. As determined according to the PTS RH 021 / 97 test method for Category II products, the defibrated pulp was uniform and free of defects. No issues of foaming or high air content were observed.

[0109] Example 4 (Comparative Example) - Base sheet containing 100% by weight of fresh CTMP A base sheet containing 100% by weight of fresh CTMP was prepared according to the base sheet preparation method. The pulp and the prepared sheet were characterized. The results are shown in Table 1.

[0110] Example 5 (Comparative Example) - Base sheet containing 10% by weight of uncoated recycled broken wood. A base sheet was prepared according to the base sheet preparation method, containing 90% by weight of fresh CTMP and 10% by weight of uncoated recycled broken pulp (UCB, the 3-ply base cardboard used above). The pulp and the prepared sheet were characterized. The results are shown in Table 1.

[0111] Example 6 (Comparative Example) - Base sheet containing 20% ​​by weight of uncoated recycled broken wood. A base sheet was prepared according to the base sheet preparation method, containing 80% by weight of fresh CTMP and 20% by weight of uncoated recycled broken pulp (UCB, the 3-ply base cardboard used above). The pulp and the prepared sheet were characterized. The results are shown in Table 1.

[0112] Example 7 (Comparative Example) - Base sheet containing 100% by weight of uncoated recycled broken wood. A base sheet containing 100% by weight of uncoated recycled broken pulp (UCB, the 3-ply base cardboard used above) was prepared according to the base sheet preparation method. The pulp and the prepared sheet were characterized. The results are shown in Table 1.

[0113] Example 8 - Base sheet containing 10% by weight of coated recycled broken wood A base sheet containing 10% by weight of PHA2-coated broken pulp (CB, Example 3) and 90% by weight of CTMP was prepared according to the base sheet preparation method. The pulp and the prepared sheet were characterized. The results are shown in Table 1. The stiffness index, z-strength, and tensile index were at approximately the same level as the reference sample, but the bulkiness was slightly improved.

[0114] Example 9 - Base sheet containing 20% ​​by weight of coated recycled broken wood. A base sheet containing 20% ​​by weight of PHA2-coated broken pulp (CB, Example 3) and 80% by weight of CTMP was prepared according to the base sheet preparation method. The pulp and the prepared sheet were characterized. The results are shown in Table 1. The stiffness index, z-strength, and tensile index were at approximately the same level as the reference sample, but the bulkiness was slightly improved.

[0115] Example 10 - Base sheet containing 100% by weight of coated recycled broken wood. A base sheet containing 100% by weight of coated broken pulp (CB, Example 3) was prepared according to the base sheet preparation method. The pulp and the prepared sheet were characterized. The results are shown in Table 1. High content of broken pulp resulted in a decrease in strength properties, but the effect was surprisingly small, especially with respect to the tensile index. However, the drainage resistance was even lower than the comparative standard.

[0116] The excellent drainage behavior, low or no tendency to foam, and the maintenance of the strength properties of the formed sheets demonstrate that PHA2 coating dispersions are suitable for online / offline dispersion coating of paperboard, and that the coated paperboard can be defibrated and reused as coated broken paper. TIFF2026511011000002.tif121170

[0117] Analysis method The pulp and sheets were characterized using the following analytical methods. Drainage resistance was determined according to SCAN C19:65. The bulkiness was determined according to ISO 534:2011. The density was determined according to ISO 534:2011. The basis weight was determined according to the ISO 536:2019 standard. The tensile index was determined according to ISO 1924-3:2005. The stiffness index was determined according to ISO 1924-3:2005. The tensile strength (kN / m) was determined according to ISO 1924-3:2005. The z intensity was determined according to ISO 15754:2009. SQD is calculated according to the following formula, where the process sample sheet is a sheet prepared using only recycled PHA dispersion coated brokens, or a sheet prepared using a mixture of recycled PHA dispersion coated brokens and fresh CTMP, and the laboratory sample sheet is a sheet prepared using only fresh CTMP. TIFF2026511011000003.tif16170

Claims

1. A method for producing a dispersion-coated fiber substrate, wherein the method is a) A step of obtaining a fibrous substrate having a first main surface and a second main surface by forming a fiber web from one or more fiber suspensions, dehydrating the fiber web, and optionally drying it, wherein at least one of the fiber suspensions is a broken suspension, b) A step of forming a dispersion coating layer on a first main surface by applying a dispersion coating composition, and drying the applied dispersion coating composition to obtain a dispersion coating fiber substrate, wherein the dispersion coating composition is in a liquid medium, Dispersed polyhydroxyalkanoate (PHA) particles in an amount of 50 to 99% by weight relative to the total solid content of the dispersion coating composition, and A dissolved low molecular weight polyol dispersant in an amount of 1 to 50% by weight relative to the total solid content of the dispersion coating composition. Includes, The total solid content of the dispersion coating composition is in the range of 20 to 80% by weight. A process to obtain a dispersed coating fiber-based substrate and Includes, a) A method wherein the Broke suspension contains 0.1 to 20% by weight of PHA based on the total solids content of the Broke suspension.

2. The method according to claim 1, wherein the Broke suspension of a) contains 0.1 to 15% by weight, preferably 0.1 to 10% by weight, and more preferably 0.1 to 5% by weight of PHA, based on the total solid content of the Broke suspension.

3. The method according to claim 1 or 2, wherein the fibrous substrate obtained in a) contains 0.1 to 5% by weight, preferably 0.1 to 2.5% by weight, and more preferably 0.1 to 2% by weight of PHA, based on the total solid content of the fibrous substrate.

4. The method according to any one of claims 1 to 3, wherein the method comprises recycling fibers from PHA dispersion coated brokens formed in the method of the present invention for producing a broken suspension dispersion coated fiber substrate of a).

5. The method according to any one of claims 1 to 4, wherein 1 to 100% by weight of the fibers of the broken suspension of a) are derived from PHA dispersion coated broken fibers recycled from a method for producing a dispersion coated fiber substrate.

6. The method according to any one of claims 1 to 5, wherein the PHA in the broken suspension of a) is derived from PHA dispersion coating broken material recycled from a method for producing a dispersion coating fiber substrate.

7. The method according to any one of claims 1 to 6, wherein the fiber web formed in a) is a multilayer fiber web comprising an upper layer, an intermediate layer, and a lower layer, the intermediate layer being formed from a Broke suspension.

8. The method according to any one of claims 1 to 7, wherein the PHA particles contain 70 to 99.9% by weight, preferably 90 to 99.9% by weight, of PHA based on the dry weight of the PHA particles.

9. PHA is poly(3-hydroxyoctanoate)(PHO), poly(3-hydroxydecanoate)(PHD), poly(3-hydroxyhexanoate)(PHH), and poly(3-hydroxyvalerate)(PHV), poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)(PHBH), poly(3-hydroxybutyrate-co-4 The method according to any one of claims 1 to 8, selected from the group consisting of (-hydroxybutyrate) (P3HB4HB), poly(3-hydroxyoctanoate-co-3-hydroxyhexanoate) (PHOHH), poly(3-hydroxyoctanoate-co-3-hydroxydecanoate) (PHOHD), and poly(3-hydroxyoctanoate-co-3-hydroxydodecanoate) (PHHDHDD), or a combination thereof.

10. The method according to any one of claims 1 to 9, wherein PHA is a PHA copolymer.

11. The method according to any one of claims 1 to 10, wherein PHA is selected from the group consisting of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxyoctanoate-co-3-hydroxyhexanoate) (PHOHH), poly(3-hydroxyoctanoate-co-3-hydroxydecanoate) (PHOHD), and poly(3-hydroxyoctanoate-co-3-hydroxydodecanoate) (PHHDHDD), or a combination thereof.

12. The method according to any one of claims 1 to 11, wherein the PHA is a medium-chain PHA, preferably a PHA having 6 to 14 carbon atoms per monomer unit.

13. The method according to any one of claims 1 to 12, wherein the dispersed coating composition comprises 3 to 35% by weight, more preferably 5 to 30% by weight, of a low molecular weight polyol dispersant based on the total solid content of the dispersed coating composition.

14. The method according to any one of claims 1 to 13, wherein the low molecular weight polyol dispersant has a molecular weight in the range of 50 to 2000 g / mol, preferably in the range of 50 to 1500 g / mol, more preferably in the range of 50 to 1000 g / mol or in the range of 50 to 500 g / mol.

15. The method according to any one of claims 1 to 14, wherein the low molecular weight polyol dispersant is selected from the group consisting of low molecular weight polysaccharides and sugar alcohols, and combinations thereof.

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