Pulp composition and pulp molded article prepared using same

Abstract

The present invention provides a pulp composition comprising paper, a polyester component selected from the group consisting of polylactic acid (PLA), polyhydroxyalkanoates (PHA), polybutylene succinate (PBS), polyadipic acid / butylene terephthalate (PBAT), polycaprolactone (PCL), polypropylene carbonate (PPC), and a non-polyester component of a microbial biomass source selected from the group consisting of bacteria and fungi. The invention also provides a method for preparing a paper pulp molded product by using the paper pulp composition. The paper pulp molded product provided by the invention has improved tensile strength, bending strength and powder falling rate.

Description

Technical Field

[0001] This invention relates to the fields of environmentally friendly packaging materials and bioengineering. Specifically, this invention relates to a pulp composition comprising paper, a polyester component, and a non-polyester component derived from microbial biomass. Using said pulp composition, molded pulp articles with improved tensile strength, flexural strength, and dust loss can be prepared. Background Technology

[0002] Pulp molded products are widely used in various packaging fields, especially in the packaging of electronic products.

[0003] Traditional molded pulp products are made by dissolving recycled paper or old newspapers in water to form pulp, which is then molded and dried. While such molded pulp products have advantages such as being environmentally friendly and recyclable, they can easily generate dust during use.

[0004] Electronic products have high requirements for packaging materials, as dust poses a potential risk. Dust can not only contaminate electronic components but also generate static electricity, which can damage sensitive electronic components. Packaging materials for electronic products need to be low in dust and high in strength to ensure that the products are protected from damage during transportation and storage.

[0005] To improve the application of pulp molding materials in electronic product packaging, it is necessary to address the dust problem inherent in traditional pulp molding materials and enhance their strength. In recent years, several improvement methods have been proposed by adding various additives to the pulp and refining the manufacturing process. For example, using a dust-resistant coating can reduce dust and improve surface smoothness and material density. However, the added chemical additives are environmentally unfriendly.

[0006] Biosynthetic polyesters, such as polyhydroxyalkanoates (PHAs), are a class of biodegradable plastics synthesized by microorganisms, serving as an environmentally friendly alternative to petroleum-based plastics. PHAs are produced by microorganisms using sugars or vegetable oils as carbon sources through a fermentation process. Biosynthetic polyesters are characterized by good biocompatibility, biodegradability, and non-toxicity, thus possessing broad potential applications in medical, packaging, agricultural, and marine fields. Compared to traditional petroleum-derived plastics, biosynthetic polyesters degrade more readily and completely in the natural environment, leaving no harmful residues.

[0007] Existing technology CN117661361A discloses the addition of resin fibers such as PLA, PHA, PBS, PBAT, PCL, and PPC as a binder pulp material, thereby reducing dust and improving product strength. Paper fiber is a hydrophilic material with strong hygroscopicity and a density of 0.5-0.9 g / cm³. 3While suspended in water, single-component resin fibers such as polylactic acid (PLA, also known as "polylactide") are hydrophobic materials that do not absorb water and have a density of 1.25 g / cm³. 3 It is easy to settle in water, which makes it easy for resin fibers and paper fibers to separate into phases and not easily dispersed evenly in the pulp. This results in products that are prone to powdering and linting and have uneven strength properties.

[0008] Therefore, existing technologies still have many problems, such as the high complexity of manufacturing pulp molded products; the need for multiple processes, including the crushing, fiberization and screening of raw materials, which increases the complexity of production and equipment requirements; poor cost control; dust problems; and the fact that resin fiber is a hydrophobic material, which is difficult to mix evenly with hydrophilic pulp, resulting in uneven molded products.

[0009] Therefore, there remains a need in the field for biodegradable and nontoxic pulp molded articles with improved tensile strength, flexural strength and dust loss. Summary of the Invention

[0010] This invention provides a pulp composition comprising paper, a polyester component, and a non-polyester component derived from microbial biomass. During the molding of pulp molded articles using this pulp composition, the non-polyester component derived from microbial biomass in the pulp composition serves to uniformly disperse the polyester component within the pulp. When the pulp composition of this invention is heated and dried, the uniformly dispersed polyester component melts and tightly binds to the pulp. This not only reduces dust problems in pulp molded articles but also significantly improves the strength of the pulp molded articles, enabling them to better protect electronic products as packaging materials.

[0011] Therefore, in a first aspect, the present invention provides a pulp composition characterized by comprising a non-polyester component including paper, a polyester component, and a microbial biomass source, for example, the polyester being selected from polylactic acid (PLA), polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), polybutylene adipate / terephthalate (PBAT), polycaprolactone (PCL), and polypropylene carbonate (PPC), preferably, the polyester having a weight average molecular weight of 150,000 Daltons or more; for example, the microbial biomass source is selected from bacteria and fungi.

[0012] In some embodiments, the pulp composition of the present invention is characterized in that the polyester component and the non-polyester component of the microbial biomass source are microbial cells with complete cell structures, such as cultured microorganisms that produce polyester components in vivo; or the polyester component and the non-polyester component of the microbial biomass source are separated, such as separated polyester components and separated non-polyester components of the microbial biomass source obtained by destroying the cell structure of cultured microorganisms that produce polyester components in vivo.

[0013] In some embodiments, the pulp composition of the present invention is characterized in that the polyester component is present in and / or outside the microorganisms.

[0014] In some embodiments, the pulp composition of the present invention is characterized in that the microbial biomass source is a microorganism capable of biosynthesizing polyester, such as bacteria and fungi, preferably bacteria, for example selected from the genera *Cupriavidus*, *Ralstonia*, *Wautersia*, *Halomonas*, *Aeromonas*, *Escherichia*, *Alcaligenes*, and *Pseudomonas*; more preferably selected are *Cupriavidusnecator*, *Wautersia eutropha*, *Ralstonia eutropha*, *Halomonas bluephagenesis*, *Aeromonas bestiarum*, *Escherichia coli*, and *Alcaligenes*. *Pseudomonas faecalis*, *Pseudomonas aeruginosa*, and *Halomonas campaniensis*, for example, *DSM 541*, *Aerobic Waters* H16, *Aerobic Rawlston* H16, PHB leak strain JMP222, *Aeromonas aureus* Ace-12, and *Halomonas campaniensis* LS21.

[0015] In some embodiments, the polyester of the pulp composition of the present invention is a PHA, for example, poly(3-hydroxybutyrate) (PHB), preferably a copolymer PHA, for example, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyheptanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), poly(3-hydroxybutyrate-co-4-hydroxyvalerate); more preferably, a copolymer PHA obtained by polymerizing one or more monomers selected from 2-hydroxyalkanoic acid, 3-hydroxyalkanoic acid (excluding 3HHx) and 4-hydroxyalkanoic acid with carbon atoms of 4 to 16 with 3-hydroxyhexanoic acid (3HHx), for example, P(3HB-co-3HHx).

[0016] In some embodiments, the paper in the pulp composition of the present invention is waste paper or recycled paper, for example, waste paper includes discarded or used copy paper, computer printing paper, notebook paper, notepad paper, typewriter paper, newspapers, magazines, cardboard and paper-based packaging materials.

[0017] In some embodiments, the pulp composition of the present invention is characterized in that, relative to 100 parts by weight of the paper, the amount of the polyester component added is 1-50 parts by weight, and the amount of the non-polyester component of the microbial biomass source added is 1-50 parts by weight.

[0018] In some embodiments, the pulp composition of the present invention is characterized in that the ratio of the amount of the polyester component added to the amount of the non-polyester component of the microbial biomass source added is 2:1 to 1:5, preferably 1.5:1 to 1:3, and more preferably 1:1 to 1:1.5.

[0019] In a second aspect, the present invention provides a method for preparing molded pulp articles, characterized by comprising the following steps:

[0020] a) Mix the pulp composition according to the first aspect of the present invention evenly in water; and

[0021] b) Heat and shape the product from step a) and dry it.

[0022] In some embodiments, the method of the present invention for preparing molded pulp articles further includes, prior to step a), the following:

[0023] a1) Cultivate microorganisms such as bacteria to synthesize polyester within the microorganisms such as bacteria.

[0024] Then, step a) is performed on the microorganisms, such as bacteria, after the culture medium has been removed.

[0025] In some embodiments, the method of the present invention for preparing molded pulp articles further includes, prior to step a), the following:

[0026] a1) Cultivate microorganisms such as bacteria to synthesize polyesters within the microorganisms such as bacteria; and

[0027] a2) Physically, chemically, or biologically treat microorganisms, such as bacteria, after removing the culture medium to obtain a mixture of non-polyester components containing microbial biomass (such as bacterial biomass) and polyester; for example, the physical treatment is treatment using supercritical or subcritical fluids, and the biological treatment is treatment with lysozyme; or feeding microorganisms, such as bacteria, after removing the culture medium to animals, such as insects, and obtaining a mixture of non-polyester components containing microbial biomass (such as bacterial biomass) and polyester by recovering the animal excrement.

[0028] In some embodiments, in the method of the present invention for preparing pulp molded articles, the heating and molding temperature of step b) is 10°C below the melting point of polyester to 50°C above the melting point of polyester, preferably 5°C below the melting point to 50°C above the melting point of polyester, and more preferably 5°C below the melting point to 30°C above the melting point of polyester.

[0029] In a third aspect, the present invention provides a pulp molded article obtained by the method of the present invention for preparing pulp molded articles.

[0030] In a fourth aspect, the present invention provides the use of the pulp composition of the present invention for the production of pulp molded articles. Detailed Implementation

[0031] Unless otherwise defined below, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. All publications, patent applications, patents, and other references mentioned herein are incorporated herein by reference in their entirety. Furthermore, the materials, methods, and examples described herein are illustrative only and are not intended to be limiting. Other features, objects, and advantages of the invention will become apparent from this specification and the accompanying drawings, and from the appended claims.

[0032] I. Definition

[0033] In this document, the term "about" when used in conjunction with a numeric value means to cover a range of numeric values ​​having a lower limit of 5% less than the specified numeric value and an upper limit of 5% greater than the specified numeric value. The term is also intended to cover values ​​within ±1%, ±0.5%, or ±0.1% of the specified numeric value.

[0034] In this document, the expression “and / or” is used to refer to any one of the listed related items, or any and all possible combinations of multiple listed related items.

[0035] In this document, the terms "comprising" or "including" mean including the stated elements, integers, or steps, or groups of elements, integers, or steps, but do not exclude any other elements, integers, or steps, or other groups of elements, integers, or steps. When the terms "comprising" or "including" are used herein, unless otherwise specified, they also cover situations consisting of the stated elements, integers, or steps.

[0036] The term "polybutylene succinate" is abbreviated as PBS, which is a biodegradable polymer synthesized from succinic acid and 1,4-butanediol.

[0037] The term "polybutylene adipate / terephthalate" is abbreviated as PBAT. It is a copolymer of butylene adipate and butylene terephthalate, possessing characteristics of both PBA (polybutylene adipate) and PBT (polybutylene terephthalate). PBAT is a material with good toughness and high elongation but low strength. PBAT has a Tg of -30℃, a crystallization temperature of 110℃, a melting temperature of 130℃, and a decomposition temperature of 375℃.

[0038] The term "poly-ε-caprolactone," abbreviated as polycaprolactone (PCL), is a semi-crystalline, biodegradable polymer. It can be used as a cell growth support material, is compatible with many conventional plastics, and completely degrades in 6-12 months under natural conditions.

[0039] The term "recycled paper" refers to paper produced from waste paper through a series of processes, including shredding, decolorizing, and pulping. Since 80% of its raw materials come from recycled waste paper, it is a low-energy, low-pollution, and environmentally friendly type of paper.

[0040] The terms "pulp molding" and "plant fiber molding" are used interchangeably. Both refer to molded products made from waste paper or plant fibers, formed into specific shapes using special molds on a molding machine. Plant fibers include, but are not limited to, wood fibers, sugarcane fibers, bamboo fibers, and straw fibers (e.g., wheat straw, rice straw, corn stalks, cotton stalks), etc., and are widely available. The primary function of pulp molding products is to contain and protect the packaged product.

[0041] II. Pulp Composition

[0042] The present invention provides a pulp composition comprising paper, a polyester component and a non-polyester component derived from microbial biomass.

[0043] There are no particular restrictions on the source of the component "paper" in the pulp composition. Recycled paper such as cardboard boxes and waste newspapers can be used, as well as recycled paper and paper obtained through general papermaking processes.

[0044] There is no particular limitation on the component "polyester" in the pulp composition, but it is preferably a biodegradable polyester. In some embodiments, the polyester is selected from polylactic acid (PLA), polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), polybutylene adipate / terephthalate (PBAT), polycaprolactone (PCL), and polypropylene carbonate (PPC). In some embodiments, the polyester may be present in microorganisms such as bacteria and / or outside microorganisms such as bacteria, preferably in microorganisms such as bacteria.

[0045] In some embodiments, the polyester has a weight average molecular weight of more than 150,000 (e.g., 200,000, 300,000, 400,000, 500,000, 600,000, 700,000, 800,000, 900,000, 1,000, 120,000, 150,000, 180,000, 2,000, 2,500, 3,000, 3,500, 4,000, 4,500, or 4,800,000) Daltons, for example 150,000 to 5,000,000, preferably 200,000 to 4,000,000, 200,000 to 3,500,000, or 500,000 to 3,500,000, or even 600,000 to 3,000,000, 800,000 to 2,500,000, or 800,000 to 2,000,000 Daltons).

[0046] In some embodiments, the amount of the polyester component added relative to 100 parts by weight of the paper is 0.8-70 parts by weight (e.g., 1, 2, 5, 10, 15, 20, 30, 40, 50, 60 or 65 parts by weight), preferably 1-60 parts by weight, 1-50 parts by weight, 10-50 parts by weight or 15-50 parts by weight.

[0047] In some embodiments, the amount of the non-polyester component of the microbial biomass source added relative to 100 parts by weight of the paper is 0.8-70 parts by weight (e.g., 1, 2, 5, 10, 15, 20, 30, 40, 50, 60 or 65 parts by weight), preferably 1-60 parts by weight, 1-50 parts by weight, 10-50 parts by weight or 15-50 parts by weight.

[0048] In some embodiments, the ratio of the amount of the polyester component added to the amount of the non-polyester component of the microbial biomass source is 2:1 to 1:5 (e.g., 1.8:1, 1.5:1, 1.2:1, 1:1, 1:1.5, 1:2, 1:3 or 1:4), preferably 1.5:1 to 1:3, and more preferably 1:1 to 1:1.5.

[0049] There is no particular limitation on the "non-polyester component of microbial biomass" in the pulp composition, as long as it is a non-polyester component of microbial cells. In some embodiments, the microorganism is any microorganism capable of biosynthesizing polyhydroxyalkanoates (PHAs), and there is no particular limitation on the source and species of the microorganism. In some embodiments, the microorganisms capable of biosynthesizing polyhydroxyalkanoates (PHAs) are bacteria and fungi, preferably bacteria, for example selected from the genera *Cupriavidus*, *Ralstonia*, *Wautersia*, *Halomonas*, *Aeromonas*, *Escherichia*, *Alcaligenes*, and *Pseudomonas*; more preferably selected are *Cupriavidus necator*, *Wautersia eutropha*, *Ralstonia eutropha*, *Halomonas bluephagenesis*, *Aeromonas bestiarum*, *Escherichia coli*, *Alcaligenes faecalis*, and *Pseudomonas aeruginosa*. aeruginosa and Halomonas campaniensis.

[0050] In some embodiments, microorganisms that synthesize PHA in vivo consist of two parts: a "microbial non-PHA component" and a synthesized "PHA component". In one embodiment, bacteria that synthesize PHA in vivo consist of two parts: a "bacterial non-PHA component" and a synthesized "PHA component".

[0051] In some specific embodiments, the bacteria are *Bacillus thuringiensis* DSM 541, *Aerobic Watersella* H16 (purchased from the American Type Culture Collection (ATCC)), *Aerobic Rawlstonella* H16 (wild type), JMP222 (wild-type PHB leak strain) disclosed in German patent DE 3937649A1 by Steinbuchel et al. (a strain preserved in the laboratory of the Institute of Microbiology, University of Münster, Germany), *Aeromonas aeruginosa* Ace-12, and *Haloxymonas campanulatus* LS21 (a strain preserved in the China General Microbiological Culture Collection Center).

[0052] In some embodiments, the polyester component is present outside the microorganism, such as bacteria, including but not limited to the following situations: the bacteria themselves do not produce the polyester component, therefore, the bacterial cells and polyester are mixed when preparing the pulp composition of the present invention; or the polyester was originally synthesized in the bacteria, but the bacteria subsequently released the polyester outside the body; or the polyester was originally synthesized in the bacteria, but the cell structure was destroyed after the bacteria died, resulting in the formation of a mixture of polyester and bacterial cells.

[0053] In some embodiments, the "microbial biomass source" mentioned in this invention can be commercially available microorganisms such as bacterial cells, or it can be used after microbial culture, such as bacteria. Bacterial culture methods include, but are not limited to, the following steps:

[0054] The bacteria of the present invention are cultured in a culture medium, which preferably contains a carbon source, nutrients other than a carbon source, such as a nitrogen source, inorganic salts, and other organic nutrients.

[0055] The carbon source can be any carbon source that can be utilized by the microorganisms of the present invention, preferably oils and fatty acids, further preferably oils, and more preferably vegetable oils, such as palm oil, soybean oil, cottonseed oil, corn oil and other oils.

[0056] Examples of nitrogen sources include ammonia, ammonium salts such as ammonium chloride, and nitrogen-containing organic compounds such as urea, peptone, and yeast extract.

[0057] Examples of inorganic salts include potassium dihydrogen phosphate, disodium hydrogen phosphate, calcium chloride, magnesium sulfate, and sodium chloride. Examples of other organic nutrient sources include amino acids such as glycine, alanine, serine, threonine, and proline; and vitamins such as vitamin B1, vitamin B12, and vitamin C.

[0058] The conditions for culturing the bacteria of the present invention, such as the culture temperature, culture time, culture pH, and culture medium, can be those commonly used when culturing host microorganisms such as Rawstoneella, Copper-loving Bacteria, Watersella, Aeromonas, Escherichia, Alcaligenes, and Pseudomonas.

[0059] In the context of this disclosure, polyhydroxyalkanoates (PHAs) include homopolymers or copolymers (i.e., copolymer PHAs).

[0060] There is no particular limitation on the polyhydroxyalkanoate (PHA) of the present invention, but polyhydroxybutyrate (PHB) can be cited as an example. The polyhydroxyalkanoate (PHA) of the present invention is preferably a copolymer of PHA, and examples include poly(3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)], poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [P(3HB-co-4HB)], poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)], poly(3-hydroxybutyrate-co-3-hydroxyheptanoate) [P(3HB-co-3HHp)], poly(3-hydroxybutyrate-co-3-hydroxydecanoate] [P(3HB-co-3HD)], and poly(3-hydroxybutyrate-co-4-hydroxyvalerate) [P(3HB-co-4HV)].

[0061] Preferably, it is a copolymer PHA obtained by polymerizing one or more monomers selected from 2-hydroxyalkanoic acid, 3-hydroxyalkanoic acid (excluding 3HHx) and 4-hydroxyalkanoic acid with 4 to 16 carbon atoms with 3HHx, and more preferably P(3HB-co-3HHx) is a copolymer of 3-hydroxybutyric acid and 3-hydroxyhexanoic acid.

[0062] For the copolymer PHA, the preferred copolymer PHA is the 3-hydroxybutyrate copolymer, wherein the composition ratio of monomer units other than the 3-hydroxybutyrate monomer unit (preferably selected from one or more monomer units of 2-hydroxyalkanoic acid, 3-hydroxyalkanoic acid and 4-hydroxyalkanoic acid with 4 to 16 carbon atoms) is 5-90 mol% (e.g. 8, 10, 12, 15, 20, 25, 30, 35, 40, 50, 60, 70, 80 or 90 mol%), for example 5-80 mol%, 10-70 mol%, 10-60 mol%, 12-60 mol%, 15-50 mol%, 20-50 mol% or 20-40 mol%.

[0063] In this invention, there are no particular limitations on the method for recovering cultured microorganisms. Examples, but not limited to, methods include separating the bacterial cells from the culture medium using conventional means such as centrifugation and filtration after cultivation. Centrifugation is preferred for separating the bacterial cells. More preferably, a centrifuge at a speed of 2000 to 20000 rpm is used for centrifugal separation of the bacterial cells.

[0064] The molecular weight of the obtained copolymer PHA can be determined by, for example, high performance liquid chromatography. The copolymer composition (mol%) of the obtained copolymer PHA can be determined by, for example, gas chromatography, nuclear magnetic resonance, etc.

[0065] There are no particular limitations on the methods for destroying the bacterial cell structure. Examples include, but are not limited to, the following methods: after bacterial culture is completed, the culture medium is treated with supercritical or subcritical fluid, and then the bacterial residue and insoluble substances such as PHA are separated from the culture medium by conventional means such as centrifugation and filtration; or after bacterial culture is completed, an enzyme that can decompose bacterial cells is added to the culture medium, and the decomposed bacterial residue and PHA mixture are collected by conventional means such as filtration or centrifugation; or after culture is completed, the bacteria in the culture medium are separated by conventional means such as centrifugation and filtration, the dried bacteria are fed to insects or other animals, and the bacterial residue and PHA mixture are collected from the excrement of insects or other animals to prepare the pulp composition of the present invention.

[0066] III. Methods for preparing pulp molded products

[0067] The present invention provides a method for preparing pulp molded articles using the pulp composition of the present invention, the method comprising mixing the pulp composition of the present invention uniformly in water; and heating and drying the obtained mixture.

[0068] In some specific embodiments, the pulp composition (e.g., 100 parts paper, 1-50 parts polyester component and 1-50 parts non-polyester component of microbial biomass source) is dispersed in 400-600 parts water. There is no particular limitation on the choice of water content, as long as the pulp can be dispersed in water.

[0069] Under the same conditions of dispersing pulp, water will not cause quality differences in the resulting pulp molded products within this weight range. There are no particular restrictions on the choice of water; it can be general industrial water, tap water, distilled water, deionized water, etc.

[0070] Pulp dispersion methods can utilize generally known pulp dispersion methods, such as mechanical stirring, high-shear mixers, ultrasonic dispersers, and the addition of surfactants.

[0071] During the pulp dispersion process, bacteria that synthesize polyesters or a mixture containing biosynthesized polyesters after the bacterial cell structure has been disrupted can be added to ensure uniform mixing of the raw materials. Commonly known dispersion methods can be used, such as mechanical stirring, high-shear mixers, ultrasonic dispersers, and the addition of surfactants.

[0072] The dispersed pulp is injected into a molding die and heated to form the final product. The heating temperature is related to the melting point of the specific polyester. The heating temperature range is from 10°C below the polyester melting point to 50°C above the polyester melting point, preferably from 5°C below the melting point to 50°C above the polyester melting point, and more preferably from 5°C below the melting point to 30°C above the polyester melting point. The polyester melting point can be referenced, for example, the melting point provided by the manufacturer.

[0073] In some implementations, the melting point of the polyester formed within the bacteria after bacterial culture is determined using the following method: After culturing the bacteria, the culture medium is centrifuged, the supernatant is removed, and the bacterial weight is measured. Chloroform is added at approximately 100 times the bacterial weight, and the mixture is stirred thoroughly at room temperature for 1 hour. The mixture is then centrifuged, and the supernatant is collected. Methanol, at 10 times the weight of the supernatant, is added, and the mixture is stirred thoroughly at room temperature for 1 hour. The mixture is then centrifuged, the supernatant is removed, and the precipitated polyester is obtained and vacuum-dried overnight at room temperature.

[0074] The molded material, after being formed by the molding die, is dried. Commonly known methods can be used for drying, such as hot air drying, infrared drying, microwave drying, vacuum drying, and freeze drying. Hot air drying is preferred.

[0075] IV. Pulp Molded Articles and Their Uses

[0076] One aspect of the present invention relates to a pulp molded article obtained from the pulp composition of the present invention or by the method according to the present invention.

[0077] One aspect of the invention relates to the use of the pulp composition for the production of pulp molded articles.

[0078] Since the pulp composition of the present invention contains all biodegradable components, the pulp molded articles prepared using it are environmentally friendly, are more easily and completely degraded in the natural environment, and do not leave harmful residues.

[0079] When preparing pulp molded articles using the pulp composition of the present invention, the non-polyester components of the microbial biomass source in the pulp composition play a role in uniformly dispersing the polyester components in the pulp. As a result, when the obtained pulp is heated and dried, the uniformly dispersed polyester components melt and tightly bond with the pulp. This reduces the dust problem of the pulp molded articles of the present invention and also significantly improves the strength of the pulp molded articles of the present invention.

[0080] Therefore, the pulp molded articles of the present invention can be widely used as various packaging materials, especially as packaging materials for electronic and electrical products, which can ensure that electronic products are protected from damage during transportation and storage.

[0081] Example

[0082] The following embodiments are described to aid in understanding the invention. They are not intended and should not be construed in any way as limiting the scope of the invention.

[0083] In the preparation methods of pulp molded articles described herein, unless otherwise specified, all conditions were performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products. Unless otherwise specified, all reagents used in the examples were purchased from Wako Pure Chemical Industries. Furthermore, commercially available reagents do not affect the experimental results.

[0084] The State Key Laboratory of Paper and Pulp Engineering (Building A, Resource and Paper Engineering Building, Wushan Campus, South China University of Technology, No. 381 Wushan Road, Tianhe District, Guangzhou, Guangdong Province) is involved in the examples and comparative examples.

[0085] Materials and methods:

[0086] In the pulp composition of the present invention, the amount of each component is measured in parts by weight, and unless otherwise specified, the weight can be measured using a balance, scale, or other general means. However, if the polyester is present in bacterial cells or the bacterial cell structure is destroyed, the content of bacterial polyester can be determined by methods such as gas chromatography or nuclear magnetic resonance, and the components other than polyester are considered as non-polyester components of the bacteria.

[0087] In the embodiments and comparative examples of this invention, the polyester yield and copolymer composition (mol%) were determined as follows: 1 ml of sulfuric acid-methanol mixture (volume ratio of sulfuric acid to methanol 15:85) and 1 ml of chloroform were added to 15-20 mg of dried bacterial cells and sealed. The mixture was heated at 100°C for 120 minutes. After cooling to room temperature, 1 ml of deionized water was added and thoroughly mixed. The mixture was allowed to stand until the aqueous layer separated from the organic layer. The separated organic layer was analyzed by gas chromatography. A Shimadzu GC-2014 gas chromatograph was used, and a Restek Rtx-1 GC Capillary Column 1 (30 m column length, 0.25 mm inner diameter, 0.25 μm liquid film thickness) was used as the capillary column. N2 was used as the carrier gas, the column inlet pressure was 150 kPa, and 2 μl of sample was injected. The temperature conditions were: increasing the temperature at a rate of 15°C / min from an initial temperature of 70 to 280°C, and then maintaining the temperature at 280°C for 15 minutes.

[0088] The weight-average molecular weight of the obtained copolymer PHA was determined by gel permeation chromatography (GPC).

[0089] The melting point of polyester was tested using the method in GB / T 16582-1996.

[0090] The oils used in the embodiments and comparative examples of this invention were all purchased from Chenguang Biotech Group Co., Ltd.

[0091] The non-cultured bacterial cell-derived P(3HB-co-3HHx) used in the examples and comparative examples were purchased from KANEKA, P(3HB-co-3HV) from Ningbo Tianan Biotechnology Co., Ltd., P(3HB-co-4HB) from Beijing Microstructure Factory, and PHB from Sigma-Aldrich.

[0092] In this invention, the population density of bacteria is expressed as the optical density (OD) measured by ultraviolet absorption at 600 nm.

[0093] Unless otherwise specified, all water used is distilled water purchased from Wako Pure Pharmaceutical.

[0094] Performance evaluation of molding:

[0095] Tensile strength was tested using the GB / T 1040 method.

[0096] Bending strength was tested using the GB / T 9341 method.

[0097] The powder shedding rate was determined using Appendix B of GB / T 20810-2018.

[0098] Example 1. Preparation and Testing of Pulp Molded Products (Part 1)

[0099] Pulp molded products are prepared using the following method.

[0100] Bacterial Culture: DSM 541, an insecticidal copper-killing bacterium, was cultured overnight at 30°C with shaking at 200 rpm in soybean broth (TSB). The TSB medium consisted of: 17 g / L trypsin-digested casein peptone (Millipore, catalog number 1.07213), 2.5 g / L dipotassium hydrogen phosphate, 2.5 g / L glucose, 5 g / L sodium chloride, and 3 g / L papain-digested soybean peptone (Sigma-Aldrich, catalog number C6835), sterilized at 121°C for 15 minutes. When the OD600 value of the bacterial culture reached 5 or higher, 3% of the bacterial culture was added to fresh PHA production medium and cultured at 30°C with shaking for 24 hours to obtain the seed culture. 10% of the seed culture was transferred to the PHA production medium in a fermenter and cultured at 30°C for 72 hours. The PHA production medium consisted of: 4.0 g / L NaH2PO4, 4.6 g / L Na2HPO4, 0.45 g / L K2SO4, 0.8 g / L MgSO4·7H2O, 0.062 g / L CaCl2, and 1 ml / L trace metal salt solution (a solution containing 15 g / L FeCl3·6H2O, 2.4 g / L MnSO4·H2O, 2.4 g / L ZnSO4·7H2O, and 0.48 g / L CuSO4·5H2O dissolved in 0.1 N hydrochloric acid). For the carbon source, 10 g / L cottonseed oil was added to the medium; for the nitrogen source, 1.87 g / L urea was added to the medium to obtain insecticidal copper-loving bacteria that synthesize polyesters in vivo.

[0101] Bacterial isolation: The cultured bacteria were separated by centrifugation at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and the bacterial cell precipitate containing P(3HB-co-3HHx) was collected. Gas chromatography was used to detect that the biosynthesized P(3HB-co-3HHx) within the bacteria accounted for 50% of the total bacterial weight. The specific calculation method was as follows: when the polyester P(3HB-co-3HHx) was considered as 1 part by weight and the bacterial cells as 2 parts by weight, then the non-PHA component of the insecticidal copper-killing bacterium was considered as 1 part by weight, and P(3HB-co-3HHx) accounted for 50% of the total bacterial weight.

[0102] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0103] - Recycled paper: 100 sheets

[0104] - DSM 541, an insecticidal copper-loving bacterium that synthesizes P(3HB-co-3HHx) in vivo: 2 parts, of which 1 part is the non-PHA bacterial component and 1 part is P(3HB-co-3HHx), with a weight-average molecular weight (Mw) of 1.13 million, and the proportion of the copolymer component HHx is 32%.

[0105] Water: 400 servings

[0106] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 2 parts of the collected bacterial cells containing P(3HB-co-3HHx) are added and stirred evenly.

[0107] Heating and molding: The prepared pulp composition is heated and molded. The melting point of P(3HB-co-3HHx) in the bacteria is 137°C according to the melting point test. Therefore, the heating temperature is controlled at about 137°C. After drying, the pulp molded product is formed.

[0108] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 1.

[0109] Example 2. Preparation and Testing of Pulp Molded Products (Part Two)

[0110] Pulp molded products are prepared using the following method.

[0111] Bacterial culture: Same as in Example 1

[0112] Bacterial isolation: Same as in Example 1.

[0113] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0114] - Recycled paper: 100 sheets

[0115] - DSM 541, an insecticidal copper-loving bacterium that synthesizes P(3HB-co-3HHx) in vivo: 50 parts, of which 25 parts are non-PHA bacterial components and 25 parts are P(3HB-co-3HHx), with a weight-average molecular weight (Mw) of 1.13 million, and the proportion of the copolymer component HHx is 32%.

[0116] Water: 400 servings

[0117] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the collected bacterial cells containing P(3HB-co-3HHx) are added and stirred evenly.

[0118] Heating and molding: The prepared pulp composition is heated and molded. The melting point of P(3HB-co-3HHx) in the bacteria is 137°C according to the melting point test. Therefore, the heating temperature is controlled at about 137°C. After drying, the pulp molded product is formed.

[0119] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 1.

[0120] Example 3. Preparation and Testing of Pulp Molded Products (Part 3)

[0121] Pulp molded products are prepared using the following method.

[0122] Bacterial culture: Same as in Example 1

[0123] Bacterial isolation: Same as in Example 1.

[0124] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0125] - Recycled paper: 100 sheets

[0126] - DSM 541, an insecticidal copper-loving bacterium that synthesizes P(3HB-co-3HHx) in vivo: 100 parts, of which 50 parts are non-PHA bacterial components and 50 parts are P(3HB-co-3HHx), with a weight-average molecular weight (Mw) of 1.13 million, and the proportion of the copolymer component HHx is 32%.

[0127] Water: 400 servings

[0128] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 100 parts of the collected bacterial cells containing P(3HB-co-3HHx) are added and stirred evenly.

[0129] Heating and molding: The prepared pulp composition is heated and molded. The melting point of P(3HB-co-3HHx) in the bacteria is 137°C according to the melting point test. Therefore, the heating temperature is controlled at about 137°C. After drying, the pulp molded product is formed.

[0130] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 1.

[0131] Example 4. Preparation and Testing of Pulp Molded Products (Part 4)

[0132] Pulp molded products are prepared using the following method.

[0133] Bacterial culture: Same as in Example 1

[0134] Bacterial isolation: Same as in Example 1.

[0135] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0136] - Recycled paper: 100 sheets

[0137] - DSM 541, an insecticidal copper-loving bacterium that synthesizes P(3HB-co-3HHx) in vivo: 100 parts, of which 50 parts are non-PHA bacterial components and 50 parts are P(3HB-co-3HHx), with a weight-average molecular weight (Mw) of 1.13 million, and the proportion of the copolymer component HHx is 32%.

[0138] Water: 600 servings

[0139] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 600 parts of water to make pulp, and then 100 parts of the collected bacterial cells containing P(3HB-co-3HHx) are added and stirred evenly.

[0140] Heating and molding: The prepared pulp composition is heated and molded. The melting point of P(3HB-co-3HHx) in the bacteria is 137°C according to the melting point test. Therefore, the heating temperature is controlled at about 137°C. After drying, the pulp molded product is formed.

[0141] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 1.

[0142] Comparative Example 1. Preparation and testing of molded pulp articles containing bacteria-free non-PHA components and PHA components.

[0143] Pulp molded products are prepared using the following method.

[0144] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0145] - Recycled paper: 100 sheets

[0146] Water: 400 servings

[0147] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then stirred evenly.

[0148] Heating molding: The prepared pulp composition is heated and molded at a temperature of about 137°C, and then dried to form a pulp molded product.

[0149] The resulting molded pulp products were loose and produced a large amount of dust. The test results are shown in Table 1.

[0150] Comparative Example 2. Preparation and testing of molded pulp articles free of bacteria and non-PHA components

[0151] Pulp molded products are prepared using the following method.

[0152] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0153] - Recycled paper: 100 sheets

[0154] - Purchased P(3HB-co-3HHx): 50 parts, weight average molecular weight Mw is 930,000, of which the copolymer component HHx accounts for 16%.

[0155] Water: 400 servings

[0156] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and 50 parts of purchased P(3HB-co-3HHx) are added and stirred evenly.

[0157] Heating molding: The prepared pulp composition is heated and molded at a temperature of about 137°C, and then dried to form a pulp molded product.

[0158] The resulting molded pulp products were loose and produced a large amount of dust. The test results are shown in Table 1.

[0159] Comparative Example 3. Preparation and testing of pulp molded articles without PHA components

[0160] Pulp molded products are prepared using the following method.

[0161] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0162] - Recycled paper: 100 sheets

[0163] - Non-PHA bacterial fraction: 50 parts by weight. The non-PHA bacterial fraction was prepared as follows: Purchased insecticidal copper-killing bacterium DSM 541 (purchased from the American Type Culture Collection (ATCC)) was cultured overnight in soybean broth (TSB) at 30°C with shaking at 200 rpm. When the OD600 value of the bacterial culture reached 5, it was separated by centrifugation at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and the precipitate containing bacterial cells was collected. Gas chromatography analysis showed that the polyester content within the bacteria was less than 0.1% of the total bacterial weight, indicating that the bacteria did not contain PHA. The non-PHA bacterial fraction was calculated as 50 parts by weight.

[0164] Water: 400 servings

[0165] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and 50 parts of the prepared bacterial non-PHA component are added and stirred evenly.

[0166] Heating molding: The prepared pulp composition is heated and molded at a temperature of about 137°C, and then dried to form a pulp molded product.

[0167] The resulting molded pulp products were loose and produced a large amount of dust. The test results are shown in Table 1.

[0168] Table 1. Performance tests of the prepared pulp molded products

[0169] Test Results Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength MPa 31 79 105 106 11.62 20.57 11 Flexural strength MPa 72 102 210 209 29.98 61.68 29 Powder drop rate % 0.75 0.34 0.12 0.12 3.07 1.19 3

[0170] As shown in Table 1, compared with the pulp molded products made without bacterial non-PHA components and / or polyester components, which exhibited insufficient strength, dusting and linting, the pulp molded products made with the addition of bacterial non-PHA components and polyester components showed significant improvements in tensile strength, flexural strength and dusting rate.

[0171] Example 5. Preparation and testing of pulp molded articles using Rollstonella.

[0172] Pulp molded products are prepared using the following method.

[0173] Bacterial culture: Rawstone's JMP222 was inoculated into 20 ml of NB medium (3 g Bacto beef extract, 5 g Bacto peptone, 1 L distilled water, pH=7.0) and cultured overnight at 30°C. Then, it was transferred to 200 ml of NB medium and cultured for 24 hours. The cells were then collected and transferred to 500 ml of MM medium (containing 10 g sodium gluconate and 0.5 g NH4Cl, with water added to 1 L, pH=7.0) and cultured for another 48 hours.

[0174] Bacterial isolation: The cultured bacteria were separated by centrifugation at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and bacterial cells containing PHB were collected. Gas chromatography was used to detect that PHB was biosynthesized within the bacteria, accounting for 40% of the total bacterial weight.

[0175] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0176] - Recycled paper: 100 sheets

[0177] - 50 samples of Rollston's bacteria that synthesize PHB in vivo, including 30 samples of the non-PHA bacterial component and 20 samples of the PHB component. The weight-average molecular weight (Mw) of the PHB component is 1.53 million.

[0178] Water: 400 servings

[0179] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the collected bacterial cells containing PHB are added and stirred evenly.

[0180] Heating and molding: The prepared pulp composition is heated and molded. The melting point of PHB in the bacteria is 150°C according to the melting point test. Therefore, the heating temperature is controlled at about 150°C. After drying, the pulp molded product is formed.

[0181] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 2.

[0182] Example 6. Preparation and testing of pulp molded articles using *Watters* bacteria.

[0183] Pulp molded products are prepared using the following method.

[0184] Bacterial Culture: *Vorticoid vorticella* H16 was cultured overnight at 30°C with shaking at 200 rpm in soybean broth (TSB) liquid medium. The TSB liquid medium consisted of: 17 g / L trypsin-digested casein peptone, 2.5 g / L dipotassium hydrogen phosphate, 2.5 g / L glucose, 5 g / L sodium chloride, and 3 g / L papain-digested soybean peptone, sterilized at 121°C for 15 minutes. When the OD600 value of the bacterial culture reached 5 or higher, 3% of the culture was added to fresh PHA production medium, and cultured at 30°C with shaking for 24 hours to obtain the seed culture. 10% of the seed culture was transferred to the PHA production medium in the fermenter and cultured at 30°C for 72 hours. The PHA production medium consists of: 4.0 g / L NaH₂PO₄, 4.6 g / L Na₂HPO₄, 0.45 g / L K₂SO₄, 0.8 g / L MgSO₄·7H₂O, 0.062 g / L CaCl₂, and 1 ml / L trace metal salt solution (a solution containing 15 g / L FeCl₃·6H₂O, 2.4 g / L MnSO₄·H₂O, 2.4 g / L ZnSO₄·7H₂O, and 0.48 g / L CuSO₄·5H₂O dissolved in 0.1 N hydrochloric acid). For the carbon source, 10 g / L cottonseed oil is added to the medium. For the nitrogen source, 1.87 g / L urea is added to the medium.

[0185] Bacterial isolation: The cultured bacteria were separated by centrifugation at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and bacterial cells containing PHB were collected. Gas chromatography was used to detect that PHB was biosynthesized within the bacteria, accounting for 40% of the total bacterial weight.

[0186] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0187] - Recycled paper: 100 sheets

[0188] - 50 samples of oxygen-enriched Watersella H16 that synthesize PHB in vivo, including 30 samples of the non-PHA bacterial component and 20 samples of the PHB component. The weight-average molecular weight (Mw) of the PHB component is 1.07 million.

[0189] Water: 400 servings

[0190] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the collected bacterial cells containing PHB are added and stirred evenly.

[0191] Heating and molding: The prepared pulp composition is heated and molded. The melting point of PHB in the bacteria is 150°C according to the melting point test. Therefore, the heating temperature is controlled at about 150°C. After drying, the pulp molded product is formed.

[0192] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 2.

[0193] Example 7. Preparation and testing of pulp molded articles using *Haloxylon ammodendron* strains producing different PHAs (Proteinized Acids).

[0194] Pulp molded products are prepared using the following method.

[0195] Bacterial culture: H. campaniensis LS21 was inoculated into 20 ml NB medium (3 g Bacto beef extract, 5 g Bacto peptone, 1 L distilled water, pH=7.0) and cultured overnight at 30°C. Then, it was transferred to 200 ml NB medium and cultured for 24 hours. The cells were then collected and transferred to 500 ml MM medium (containing 10 g sodium gluconate and 0.5 g NH4Cl, with water added to 1 L, pH=7.0) and cultured for another 48 hours.

[0196] Bacterial isolation: The cultured bacteria were separated by centrifugation at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and bacterial cells containing PHB were collected. Gas chromatography was used to detect that PHB was biosynthesized within the bacteria, accounting for 40% of the total bacterial weight.

[0197] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0198] - Recycled paper: 100 sheets

[0199] - 50 samples of halomonas bacteria that synthesize PHB in vivo, including 30 samples of non-PHA bacterial components and 20 samples of PHB components, with a weight-average molecular weight (Mw) of 1.21 million.

[0200] Water: 400 servings

[0201] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the collected bacterial cells containing PHB are added and stirred evenly.

[0202] Heating and molding: The prepared pulp composition is heated and molded. The melting point of PHB in the bacteria is 150°C according to the melting point test. Therefore, the heating temperature is controlled at about 150°C. After drying, the pulp molded product is formed.

[0203] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 2.

[0204] Example 8. Preparation and Testing of Molded Pulp Products Using Halomonas Bacteria Producing Different PHAs (Part 2)

[0205] Pulp molded products are prepared using the following method.

[0206] Bacterial culture: *H. bluephagenesis* TD08 (prpC gene knockout) strain was inoculated into 20 ml of NB medium (3 g Bacto beef extract, 5 g Bacto peptone, 1 L distilled water, pH = 7.0) (see Yin, J. et al. (2015). Effects of chromosomal gene copy number and locations on polyhydroxyalkanoate synthesis by *Escherichia coli* and *Halomonas* sp. *Appl. Microbiol. Biotechnol.* 99, 5523-5534. doi:10.1007 / s00253-015-6510-8). The cells were cultured overnight at 30°C, then transferred to 200 ml of NB medium. After 24 hours of culture, cells were collected and transferred to 500 ml of MM medium (containing 10 g sodium gluconate and 0.5 g NH4Cl, with water added to 1 L, pH = 7.0), and cultured for another 48 hours.

[0207] Bacterial isolation: The cultured bacteria were separated by centrifugation at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and bacterial cells containing P(3HB-co-3HV) were collected. Gas chromatography analysis showed that P(3HB-co-3HV) was biosynthesized within the bacteria, accounting for 40% of the total bacterial weight.

[0208] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0209] - Recycled paper: 100 sheets

[0210] - Halomonas bacteria that synthesize P(3HB-co-3HV) in vivo: 50 samples, of which 30 samples contained the non-PHA bacterial component and 20 samples contained the P(3HB-co-3HV) component, with a weight-average molecular weight (Mw) of 1.72 million, and the proportion of the copolymer component 3HV was 12%.

[0211] Water: 400 servings

[0212] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the collected bacterial cells containing P(3HB-co-3HV) are added and stirred evenly.

[0213] Heating and molding: The prepared pulp composition is heated and molded. The melting point of P(3HB-co-3HV) in the bacteria is 137°C according to the melting point test. Therefore, the heating temperature is controlled at about 137°C. After drying, the pulp molded product is formed.

[0214] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 2.

[0215] Example 9. Preparation and Testing of Molded Pulp Products Using Halomonas Bacteria Producing Different PHAs (Part 3)

[0216] Pulp molded products are prepared using the following method.

[0217] Bacterial culture: H. bluephagenesis TD40 strain (see CN 109504714A) was inoculated into 20 ml NB medium (3 g Bacto beef extract, 5 g Bacto peptone, 1 L distilled water, pH=7.0) and cultured overnight at 30°C. Then, the cells were transferred to 200 ml NB medium and cultured for 24 hours. The cells were then collected and transferred to 500 ml MM medium (containing 5 g γ-butyrolactone, 5 g sodium gluconate and 0.5 g NH4Cl, with water added to 1 L, pH=7.0) and cultured for another 48 hours.

[0218] Bacterial isolation: The cultured bacteria were separated by centrifugation at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and bacterial cells containing P(3HB-co-4HB) were collected. Gas chromatography analysis showed that P(3HB-co-4HB) was biosynthesized within the bacteria, accounting for 40% of the total bacterial weight.

[0219] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0220] - Recycled paper: 100 sheets

[0221] - Halomonas bacteria that synthesize P(3HB-co-4HB) in vivo: 50 samples, of which 30 samples contained the non-PHA bacterial component and 20 samples contained the P(3HB-co-4HB) component. The weight average molecular weight (Mw) was 1.44 million, and the proportion of the copolymer component 4HB was 10%.

[0222] Water: 400 servings

[0223] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the collected bacterial cells containing P(3HB-co-4HB) are added and stirred evenly.

[0224] Heating and molding: The prepared pulp composition is heated and molded. The melting point of P(3HB-co-4HB) in the bacteria is 131°C according to the melting point test. Therefore, the heating temperature is controlled at about 131°C. After drying, the pulp molded product is formed.

[0225] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 2.

[0226] Table 2. Performance tests of the prepared pulp molded products

[0227] Test Results Example 5 Example 6 Example 7 Example 8 Example 9 Tensile strength MPa 73 71 83 70 70 Flexural strength MPa 83 80 79 90 111 Powder drop rate % 0.52 0.52 0.52 0.31 0.31

[0228] As shown in Table 2, different PHAs (e.g., PHB, P(3HB-co-3HV), P(3HB-co-4HB)) were prepared using different bacteria. The pulp molded products prepared after adding non-PHA bacterial components and polyester components showed significant improvements in tensile strength, flexural strength and dust loss.

[0229] Example 10. Preparation and testing of molded pulp articles using treated bacteria (Part 1)

[0230] Pulp molded products are prepared using the following method.

[0231] Bacterial culture: Same as in Example 1

[0232] Bacterial treatment and isolation: 0.1% (w / w) lysozyme (Sigma-Aldrich, catalog number L6876) was added to the cultured bacteria and stirred at 50°C for 5 hours. Separation was achieved by centrifugation at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and the lower layer containing P(3HB-co-3HHx) and bacterial remnants with disrupted cell structure due to lysozyme was collected. Gas chromatography sampling revealed that P(3HB-co-3HHx) was biosynthesized within the bacteria, accounting for 50% of the total bacterial weight. Its weight-average molecular weight (Mw) was 1.13 million, with the copolymer component HHx accounting for 32%.

[0233] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0234] - Recycled paper: 100 sheets

[0235] - A mixture of 50 parts of insecticidal copper-loving bacterium DSM 541, which synthesizes P(3HB-co-3HHx) in vivo, after protease degradation, wherein P(3HB-co-3HHx) is 25 parts by weight and the non-PHA bacterial component is 25 parts by weight.

[0236] Water: 400 servings

[0237] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the mixture of DSM 541, an insecticidal copper-killing bacterium that synthesizes P(3HB-co-3HHx) in vivo and decomposed by protease are added and stirred evenly.

[0238] Heating and molding: The prepared pulp composition is heated and molded. The melting point of P(3HB-co-3HHx) in the bacteria is 137°C according to the melting point test. Therefore, the heating temperature is controlled at about 137°C. After drying, the pulp molded product is formed.

[0239] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 3.

[0240] Example 11. Preparation and testing of molded pulp articles using treated bacteria (Part 2)

[0241] Pulp molded products are prepared using the following method.

[0242] Bacterial culture: Same as in Example 1

[0243] Bacterial isolation and treatment: The cultured bacterial broth was centrifuged at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and the lower layer containing P(3HB-co-3HHx) was collected. An equal weight of water was added to the collected bacteria, and the mixture was heated to 155°C in a pressure vessel, maintaining a pressure of 0.5 MPa (subcritical water) for 1 hour. The mixture was then centrifuged again at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and the lower layer containing P(3HB-co-3HHx) and bacterial residues with disrupted cell structure due to subcritical water was collected. Gas chromatography analysis revealed that P(3HB-co-3HHx) was biosynthesized within the bacteria, accounting for 50% of the total bacterial weight. Its weight-average molecular weight (Mw) was 1.13 million, with the copolymer component HHx accounting for 32%.

[0244] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0245] - Recycled paper: 100 sheets

[0246] - A mixture of DSM 541, an insecticidal copper-loving bacterium that synthesizes P(3HB-co-3HHx) in vivo, after subcritical water treatment: 50 parts, of which P(3HB-co-3HHx) is 25 parts by weight and the non-PHA component of the bacteria is 25 parts by weight.

[0247] Water: 400 servings

[0248] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the mixture of DSM 541, an insecticidal copper-killing bacterium that synthesizes P(3HB-co-3HHx) in vivo and treated with subcritical water are added and stirred evenly.

[0249] Heating and molding: The prepared pulp composition is heated and molded. The melting point of P(3HB-co-3HHx) in the bacteria is 137°C according to the melting point test. Therefore, the heating temperature is controlled at about 137°C. After drying, the pulp molded product is formed.

[0250] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 3.

[0251] Example 12. Preparation and Testing of Molded Pulp Products Using Treated Bacteria (Part 3)

[0252] Pulp molded products are prepared using the following method.

[0253] Bacterial culture: Same as in Example 1

[0254] Bacterial isolation and treatment: The cultured bacterial broth was centrifuged at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and the lower layer containing P(3HB-co-3HHx) bacteria was collected. After drying, the bacteria were fed to mealworm larvae (scientific name: *Tenebrio molitor*) at a weight ratio of 1:10. Forty-eight hours after feeding, the mealworm excrement was collected as a bacterial mixture. The collection method was sieving using a 1 mm mesh sieve.

[0255] Gas chromatography sampling revealed that the bacterial biosynthetic component P(3HB-co-3HHx) accounted for 50% of the total bacterial weight. Its weight-average molecular weight (Mw) was 1.13 million, with the copolymer HHx comprising 32%.

[0256] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0257] - Recycled paper: 100 sheets

[0258] - Excrement collected from mealworms after feeding with DSM 541, an insecticidal copper-loving bacterium that synthesizes P(3HB-co-3HHx) in vivo: 50 parts, of which 25 parts by weight were P(3HB-co-3HHx) and 25 parts by weight were non-PHA bacterial components.

[0259] Water: 400 servings

[0260] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the excrement collected after feeding mealworms with DSM 541 containing P(3HB-co-3HHx) are added and stirred evenly.

[0261] Heating and molding: The prepared pulp composition is heated and molded. The melting point of P(3HB-co-3HHx) in the bacteria is 137°C according to the melting point test. Therefore, the heating temperature is controlled at about 137°C. After drying, the pulp molded product is formed.

[0262] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 3.

[0263] Table 3. Performance tests of the prepared pulp molded products

[0264] Test Results Example 3 Example 10 Example 11 Example 12 Tensile strength MPa 105 89 31 105 Flexural strength MPa 210 115 72 140 Powder drop rate % 0.12 0.56 1 0.03

[0265] As shown in Table 3, even if the cell structure of bacteria containing polyester is destroyed and they are added to pulp, the molded products have similar properties.

[0266] Example 13. Preparation and testing of pulp molded articles using commercially available components.

[0267] Pulp molded products are prepared using the following method.

[0268] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0269] - Recycled paper: 100 sheets

[0270] - Non-PHA bacterial fraction: 50 parts by weight. The non-PHA bacterial fraction was prepared as follows: Purchased insecticidal copper-killing bacterium DSM 541 (purchased from the American Type Culture Collection (ATCC)) was cultured overnight in soybean broth (TSB) at 30°C with shaking at 200 rpm. When the OD600 value of the bacterial culture reached 5, it was separated by centrifugation at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and the precipitate containing bacterial cells was collected. Gas chromatography analysis showed that the polyester content within the bacteria was less than 0.1% of the total bacterial weight, indicating that the bacteria did not contain PHA. The non-PHA bacterial fraction was calculated as 50 parts by weight.

[0271] - Purchased P(3HB-co-3HHx) (from Sigma-Aldrich, catalog number 915890): 50 parts. Its weight-average molecular weight (Mw) is 1.16 million, with the copolymer component HHx comprising 15%.

[0272] Water: 400 servings

[0273] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the prepared bacterial non-PHA component and 50 parts of purchased P(3HB-co-3HHx) are added and stirred evenly.

[0274] Heating molding: The prepared pulp composition is heated and molded at a temperature of about 137°C, and then dried to form a pulp molded product.

[0275] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 4.

[0276] Example 14. Preparation and Testing of Pulp Molded Articles Using Commercially Available Components (Part Two)

[0277] Pulp molded products are prepared using the following method.

[0278] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0279] - Recycled paper: 100 sheets

[0280] - Non-PHA bacterial fraction: 50 parts by weight. The non-PHA bacterial fraction was prepared as follows: Purchased insecticidal copper-killing bacterium DSM541 (purchased from the American Type Culture Collection (ATCC)) was cultured overnight in soybean broth (TSB) at 30°C with shaking at 200 rpm. When the OD600 value of the bacterial culture reached 5, it was separated by centrifugation at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and the precipitate containing bacterial cells was collected. Gas chromatography analysis showed that the polyester content within the bacteria was less than 0.1% of the total bacterial weight, indicating that the bacteria did not contain PHA. The non-PHA bacterial fraction was calculated as 50 parts by weight.

[0281] - Purchased polylactic acid (PLA) (from Anhui Fengyuan Biotechnology Co., Ltd., catalog number FY601): 50 portions. Its weight-average molecular weight (Mw) is 210,000.

[0282] Water: 400 servings

[0283] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the prepared bacterial non-PHA component and 50 parts of purchased polylactic acid (PLA) are added and stirred evenly.

[0284] Heating molding: The prepared pulp composition is heated and molded at a temperature of about 170°C, and then dried to form a pulp molded product.

[0285] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 4.

[0286] Example 15. Preparation and Testing of Pulp Molded Articles Using Commercially Available Components (Part 3)

[0287] Pulp molded products are prepared using the following method.

[0288] Preparation of pulp composition: The pulp composition is prepared in the following weight proportions.

[0289] - Recycled paper: 100 sheets

[0290] - Non-PHA bacterial fraction: 50 parts by weight. The non-PHA bacterial fraction was prepared as follows: Purchased insecticidal copper-killing bacterium DSM 541 (purchased from the American Type Culture Collection (ATCC)) was cultured overnight in soybean broth (TSB) at 30°C with shaking at 200 rpm. When the OD600 value of the bacterial culture reached 5, it was separated by centrifugation at 12,000 rpm for 20 minutes at room temperature. The supernatant was removed, and the precipitate containing bacterial cells was collected. Gas chromatography analysis showed that the polyester content within the bacteria was less than 0.1% of the total bacterial weight, indicating that the bacteria did not contain PHA. The non-PHA bacterial fraction was calculated as 50 parts by weight.

[0291] - Purchased polybutylene adipate terephthalate (PBAT) (purchased from BASF, catalog number) Batch AB 1): 50 portions. Its weight-average molecular weight (Mw) is 700,000, with butyl terephthalate units comprising 50%.

[0292] Water: 400 servings

[0293] The specific preparation method of the pulp composition is as follows: 100 parts of recycled paper are dispersed in 400 parts of water to make pulp, and then 50 parts of the prepared bacterial non-PHA component and 50 parts of purchased PBAT are added and stirred evenly.

[0294] Heating molding: The prepared pulp composition is heated and molded at a temperature of about 120°C, and then dried to form a pulp molded product.

[0295] The resulting molded pulp products were firm, with a tight appearance and no obvious dust shedding. The test results are shown in Table 4.

[0296] Table 4. Performance tests of the prepared pulp molded products

[0297] Test Results Example 3 Example 13 Example 14 Example 15 Comparative Example 2 Comparative Example 3 Tensile strength MPa 105 35 36 32 20.57 11 Flexural strength MPa 210 75 88 89 61.68 29 Powder drop rate % 0.12 0.75 0.56 0.62 1.19 3

[0298] As shown in Table 4, the performance test results indicate that, compared with Comparative Examples 2 and 3, the addition of PHA-free bacteria and polyester, respectively, can improve the performance of the resulting molding materials. However, compared with Example 3, the powder shedding rate of the molding materials with PHA-free bacteria and polyester added, respectively, is significantly higher than that with bacteria containing polyester added.

[0299] The foregoing describes exemplary embodiments of the present invention. Those skilled in the art should understand that these disclosures are merely exemplary, and various other substitutions, adaptations, and modifications can be made within the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments listed herein.

Claims

1. A pulp composition, characterized in that, The non-polyester component comprises paper, a polyester component, and a microbial biomass source. For example, the polyester is selected from polylactic acid (PLA), polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), polybutylene adipate / terephthalate (PBAT), polycaprolactone (PCL), and polypropylene carbonate (PPC). Preferably, the polyester has a weight average molecular weight of 150,000 Daltons or more. For example, the microbial biomass source is selected from bacteria and fungi.

2. The pulp composition according to claim 1, characterized in that, The polyester component and the non-polyester component of the microbial biomass source are microbial cells with complete cell structures, such as cultured microorganisms that produce polyester components in vivo; or the polyester component and the non-polyester component of the microbial biomass source are separated, such as the separated polyester component and the separated non-polyester component of the microbial biomass source obtained by destroying the cell structure of cultured microorganisms that produce polyester components in vivo.

3. The pulp composition according to claim 1 or 2, characterized in that, The polyester component exists within and / or outside the microorganisms.

4. The pulp composition according to any one of claims 1-3, characterized in that, The microbial biomass source is a microorganism capable of biosynthesizing polyester, such as bacteria and fungi, preferably bacteria, for example selected from the genera *Cupriavidus*, *Ralstonia*, *Wautersia*, *Halomonas*, *Aeromonas*, *Escherichia*, *Alcaligenes*, and *Pseudomonas*; more preferably selected are *Cupriavidusnecator*, *Wautersia eutropha*, *Ralstonia eutropha*, *Halomonas bluephagenesis*, *Aeromonas bestiarum*, *Escherichia coli*, *Alcaligenes faecalis*, and *Pseudomonas aeruginosa*. aeruginosa and Halomonas campaniensis, for example, selected suicidal copper-eating bacteria DSM 541, oxygen-enriched Waters bacillus H16, oxygen-enriched Rawlston bacillus H16, PHB leak strain JMP222, aeromonas ace-12, and Halomonas campaniensis LS21.

5. The pulp composition according to any one of claims 1-4, wherein the polyester is a PHA, for example, poly(3-hydroxybutyrate) (PHB), preferably a copolymer PHA, for example, poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate), poly(3-hydroxybutyrate-co-3-hydroxyheptanoate), poly(3-hydroxybutyrate-co-3-hydroxydecanoate), poly(3-hydroxybutyrate-co-4-hydroxyvalerate); more preferably a copolymer PHA obtained by polymerizing one or more monomers selected from 2-hydroxyalkanoic acid, 3-hydroxyalkanoic acid (excluding 3HHx) and 4-hydroxyalkanoic acid having 4 to 16 carbon atoms with 3HHx, for example, P(3HB-co-3HHx).

6. The pulp composition according to any one of claims 1-5, wherein the paper is waste paper or recycled paper, for example, the waste paper includes waste or used copy paper, computer printing paper, notebook paper, notepad paper, typewriter paper, newspapers, magazines, cardboard and paper-based packaging materials.

7. The pulp composition according to any one of claims 1-6, characterized in that, Relative to 100 parts by weight of the paper, the amount of polyester component added is 0.8-70 parts by weight, preferably 1-50 parts by weight or 10-50 parts by weight, and the amount of non-polyester component of the microbial biomass source added is 0.8-70 parts by weight, preferably 1-50 parts by weight or 10-50 parts by weight.

8. The pulp composition according to any one of claims 1-7, characterized in that, The ratio of the amount of polyester component added to the amount of non-polyester component added to the microbial biomass source is 2:1 to 1:5, preferably 1.5:1 to 1:3, and more preferably 1:1 to 1:1.

5.

9. The pulp composition according to any one of claims 1-8, characterized in that, The polyester has a weight average molecular weight of 150,000 to 5,000,000, preferably 200,000 to 4,000,000 or 500,000 to 3,500,000 Daltons.

10. A method for preparing molded pulp articles, characterized in that, Includes the following steps: a) Mixing the pulp composition according to any one of claims 1-9 evenly in water; and b) Heat and shape the product from step a) and dry it.

11. The method of claim 10, wherein prior to step a), it further comprises: a1) Cultivate microorganisms such as bacteria to synthesize polyester within the microorganisms such as bacteria. Then, step a) is performed on the microorganisms, such as bacteria, after the culture medium has been removed.

12. The method of claim 10, wherein prior to step a), it further comprises: a1) Cultivate microorganisms such as bacteria to synthesize polyesters within the microorganisms such as bacteria; and a2) Physically, chemically, or biologically treat microorganisms, such as bacteria, after removing the culture medium to obtain a mixture of non-polyester components containing microbial biomass (such as bacterial biomass) and polyester; for example, the physical treatment is treatment using supercritical or subcritical fluids, and the biological treatment is treatment with lysozyme; or feeding microorganisms, such as bacteria, after removing the culture medium to animals, such as insects, and obtaining a mixture of non-polyester components containing microbial biomass (such as bacterial biomass) and polyester by recovering the animal excrement.

13. The method according to any one of claims 10-12, wherein the heating molding temperature in step b) is 10°C below the melting point of the polyester to 50°C above the melting point of the polyester, preferably 5°C below the melting point to 50°C above the melting point of the polyester, and more preferably 5°C below the melting point to 30°C above the melting point of the polyester.

14. A pulp molded article, characterized in that, Obtained by the method according to any one of claims 10-13.

15. Use of the pulp composition according to any one of claims 1-9 for the production of pulp molded articles.