Mixed molded pulp object
By adding polymer reinforcements to the molded pulp, the mechanical stability and barrier properties of molded pulp products under humidity or liquid water conditions are solved, while maintaining biodegradability and paper feel.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOCIETE DES PRODUITS NESTLE SA
- Filing Date
- 2024-12-06
- Publication Date
- 2026-07-14
AI Technical Summary
Molded pulp products lack mechanical robustness and barrier properties, and are prone to swelling and delamination, especially when exposed to humidity or liquid water. Existing coatings or linings cannot effectively improve these problems and may impair biodegradability.
By adding polymer reinforcements to the molded pulp to form a polymer layer or dispersing the polymer throughout the pulp, a biodegradable polymer layer is combined to enhance mechanical properties and barrier properties, and a polymer layer is placed between the pulp and the tactile layer to maintain the paper feel.
It improves the mechanical strength and water resistance of molded pulp products while maintaining biodegradability, enhancing the barrier properties against oxygen and moisture, and without compromising the paper feel.
Smart Images
Figure CN122396587A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to molded pulp articles with improved robustness and / or barrier properties, and methods for producing the same. Background Technology
[0002] Molded pulp is an increasingly common material used in packaging, particularly food packaging. A key benefit of these materials is their ease of recycling and biodegradability, often making them compostable at home. Existing technologies for molded pulp allow for the production of rigid containers, such as cans, bottles, or capsules for beverages, through wetting or drying processes of cellulosic fibers. However, molded pulp products typically lack mechanical robustness, which can be exacerbated by exposure to excessive moisture or liquid water. This is especially true for molded pulp products formed through drying processes, which rapidly swell and delaminate upon exposure to water.
[0003] Internal coatings or linings are typically applied to enhance the barrier properties of molded pulp articles (e.g., against oxygen, water, and grease). However, these do not protect the external surfaces of the articles from environmental conditions. External coatings or linings can be used, but these diminish the paper feel of the molded articles. Furthermore, these coatings or linings generally do not improve the mechanical properties of molded pulp articles and may impair their biodegradability.
[0004] The purpose of this invention is to solve one or more of the aforementioned problems. Summary of the Invention
[0005] A first aspect of the present invention relates to a molded pulp article comprising: a shaped pulp comprising cellulose fibers; and a polymer reinforcement.
[0006] The polymer reinforcement may comprise a polymer dispersed throughout the forming pulp. The polymer may comprise up to 50% by weight of the total mass of the forming pulp and the polymer reinforcement, optionally between 1% and 50% by weight, optionally between 10% and 40% by weight, optionally between 20% and 30% by weight, optionally about 30% by weight.
[0007] In an embodiment, the molded pulp article further includes a tactile layer, and the polymer reinforcement includes a polymer layer located between the molded pulp and the tactile layer. The polymer layer can be a web or a film, optionally having a thickness of 1µm to 200µm, optionally 10µm to 150µm, more preferably 20µm to 120µm, further preferably 30µm to 80µm, even more preferably 40µm to 60µm, and most preferably about 50µm. The tactile layer can have a paper-like feel; optionally, the tactile layer is selected from thin pulp layers, paperboard, and paper layers. The tactile layer can have a weight of 5gsm to 150gsm, optionally 10gsm to 100gsm, optionally 15gsm to 50gsm, and optionally about 20gsm.
[0008] The polymer can be a biodegradable polymer, optionally selected from polylactic acid (PLA), polyvinyl alcohol (PVOH), polyhydroxyalkanoate (PHA), polycaprolactone (PCL), polyglycolic acid (PGA), butene glycol (BVOH), ethylene glycol (EVOH), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose), proteins (such as casein, zein, soy protein, silk protein), and combinations thereof.
[0009] A second aspect of the invention relates to a method for producing molded pulp articles, the method comprising:
[0010] a) Provides cellulose-based fiber materials;
[0011] b) Provide polymers;
[0012] c) To shape cellulose-based fibrous materials into formed pulp;
[0013] d) Heating the forming pulp to achieve at least partial melting of the polymer; and
[0014] e) Cool the formed pulp to cure the polymer.
[0015] Cellulose-based fibrous materials and polymers may be provided as mixtures, wherein the polymer is dispersed throughout the cellulose-based fibrous material. The polymer may be provided in powder and / or granule form, and the polymer is dispersed throughout the cellulose-based fibrous material by mixing the cellulose fibers with the powder and / or granules. The polymer may also be dispersed throughout the cellulose-based fibrous material by optionally mixing the cellulose fibers with an aqueous dispersion of the polymer in the presence of a surfactant.
[0016] The method may also include the step of providing a tactile layer, wherein the polymer is provided as a polymer layer between the cellulose-based fibrous material and the tactile layer.
[0017] Step c) may occur before step d). Alternatively, steps c) and d) may occur simultaneously.
[0018] Step c) may include thermoforming.
[0019] Step d) may include heating the formed pulp to a temperature below 250°C, preferably between 50°C and 200°C, more preferably between 100°C and 150°C, and most preferably about 120°C.
[0020] The third aspect of the invention relates to the use of molded pulp articles according to the first aspect of the invention for packaging edible products for human or animal consumption.
[0021] The fourth aspect of the invention relates to a packaged edible product comprising a molded pulp article according to the first aspect of the invention, the molded pulp article being at least partially filled with an edible product for human or animal consumption.
[0022] As used in this specification, the words “including,” “contains,” and similar terms should not be construed as having an exclusive or exhaustive meaning. In other words, they are intended to mean “including, but not limited to.” Attached Figure Description
[0023] Further features and advantages of the invention are described below in the description of the presently preferred embodiments given with reference to the accompanying drawings, and these features and advantages will be apparent from the description, wherein:
[0024] Figure 1 A schematic cross-section of a molded pulp article (1) according to the invention is shown. The molded pulp article (1) comprises pulp (2) with polymer reinforcement. As shown in the illustration, the polymer reinforcement is in the form of a polymer (4) dispersed throughout the fibers (3) of the pulp;
[0025] Figure 2 A schematic cross-section of a molded pulp article (1) according to the present invention is shown. The molded pulp article (1) includes pulp (5), a polymer reinforcement in the form of a polymer layer (6), and a tactile layer (7).
[0026] Figure 3 illustrates the effect of adding water droplets to conventionally produced pulp products without polymer reinforcement. Figure 3A —rapid expansion and shape loss) and the effects of adding to molded pulp articles comprising polymer reinforcements according to the invention ( Figure 3B —Reduced water intake, structure maintained).
[0027] Figure 4 shows the results of tensile strength tests on conventional molded pulp articles without polymer reinforcement and molded pulp articles including polymer reinforcement according to the present invention. Figure 4A Molded pulp articles incorporating polymer reinforcements are shown to have improved tensile strength. Figure 4B Molded pulp articles incorporating polymer reinforcements are shown to have increased tensile energy absorption. Figure 4C The molded pulp article, which includes polymer reinforcement, is shown to have increased maximum force. Figure 4D The molded pulp articles containing polymer reinforcements are shown to have a greater elongation at break. Detailed Implementation
[0028] "Fiber" refers to cellulose fibers that are usually extracted from plants, seeds, or trees; such fibers contain not only cellulose molecules, but also hemicellulose and lignin.
[0029] Molded pulp products, also known as molded fiber products, refer to products formed by molding fiber materials. These fiber materials can be obtained from recycled fiber sources such as paper or paperboard, or directly from natural fiber sources such as bagasse, bamboo, and straw. Molded pulp products are commonly used in packaging and are widely considered sustainable.
[0030] Molded pulp products
[0031] A first aspect of the invention relates to a molded pulp article. The molded pulp article comprises a shaped pulp containing cellulose fibers and polymer reinforcements. The polymer reinforcements increase the mechanical strength of the molded pulp and enhance its water resistance. Furthermore, the polymers can improve the barrier properties of the molded pulp article against oxygen and / or moisture.
[0032] In a first embodiment, the polymer reinforcement comprises a polymer dispersed throughout the molding pulp. Unbound by theory, it is believed that the polymer in the pulp and the cellulosic fibers form a binding network, immobilizing the cellulosic fibers and enhancing the stiffness and strength of the molded pulp article. The polymer may comprise up to 50% by weight of the total mass of the molding pulp, optionally between 1% and 50% by weight, optionally between 10% and 40% by weight, optionally between 20% and 30% by weight, and optionally about 30% by weight. These loadings are sufficient to improve the mechanical properties of the molded pulp article without compromising its tactile qualities (i.e., its papery texture).
[0033] In a second embodiment, the polymer reinforcement includes a polymer layer disposed between the outer surface of the molded pulp and the inner surface of the tactile layer. The polymer layer reinforces the molded pulp and acts as a binder to attach the tactile layer to the molded pulp. The tactile layer retains the paper feel of the molded pulp article and is optionally selected from thin pulp layers, paperboard, and paper layers. The tactile layer may have a weight of 5 gsm to 150 gsm, optionally 10 gsm to 100 gsm, optionally 15 gsm to 50 gsm, optionally about 20 gsm.
[0034] The polymer layer can be in the form of a web or a film. A web has openings that partially cover the surface of the molded pulp, reducing the amount of polymer required while still achieving reinforcing and adhesive functions. A film provides a substantially continuous cover to the surface of the molded pulp, thus providing the additional function of a barrier layer, inhibiting the movement of gases and water through the molded pulp article. The polymer layer can have a thickness of 1µm to 200µm, preferably 10µm to 150µm, more preferably 20µm to 120µm, further preferably 30µm to 80µm, even more preferably 40µm to 60µm, and most preferably about 50µm. In an embodiment, the polymer layer thickness is about 100µm.
[0035] It should be understood that the aforementioned embodiments can be combined (i.e., the molded pulp article may include a polymer dispersed throughout the molded pulp and a polymer reinforcement in the form of polymer layers). It should also be understood that the molded pulp article may include multiple layers of polymer reinforcement and / or molded pulp; for example, the molded pulp article may include one or more additional polymer layers and one or more additional molded pulp layers, the one or more additional polymer layers being disposed between the molded pulp layers.
[0036] In any of the foregoing embodiments, the polymer can be a biodegradable polymer. Using a biodegradable polymer ensures that the biodegradable properties of the molded pulp products and the resulting environmental benefits are maintained. Biodegradable polymers can be selected from polylactic acid (PLA), polyvinyl alcohol (PVOH), polyhydroxyalkanoates (PHA), polycaprolactone (PCL), polyglycolic acid (PGA), butene glycol (BVOH), ethylene vinyl alcohol (EVOH), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose), proteins (such as casein, zein, soy protein, silk protein), and combinations thereof. In embodiments, the polymer has a melting point below 200°C (such as 100°C to 200°C, 100°C to 150°C, or 100°C to 120°C).
[0037] Those skilled in the art will understand that, depending on the intended contents of the molded pulp article, the molded pulp article may include additional layers. For example, the molded pulp article may also include any of the following: an inorganic barrier layer, an organic barrier layer, an ink layer, an overprinting varnish, a contact layer, etc.
[0038] Method for producing molded pulp products
[0039] A second aspect of the present invention relates to a method for producing molded pulp articles, the method comprising the following steps:
[0040] a) Provides cellulose-based fiber materials;
[0041] b) Provide polymers;
[0042] c) To shape cellulose-based fibrous materials into formed pulp;
[0043] d) Heating the forming pulp to melt the polymer; and
[0044] e) Cool the formed pulp to cure the polymer.
[0045] In a first embodiment, the cellulose-based fibrous material and the polymer are provided as a mixture, wherein the polymer is dispersed throughout the cellulose-based fibrous material. Preferably, the polymer is dispersed substantially uniformly throughout the cellulose-based fibrous material.
[0046] The polymer may be provided as a solid, such as in the form of powder and / or granules. The polymer powder or granules may have particle sizes below 500 µm, below 250 µm, or below 100 µm, such as 0.1 µm to 500 µm, 0.5 µm to 250 µm, 1 µm to 100 µm, 5 µm to 50 µm, or 10 µm to 20 µm. The solid polymer is mixed with the cellulosic fibers until it is uniformly dispersed throughout. Any suitable mixing method may be used, such as a ball mill. The cellulosic fibrous material (and the solid polymer mixed therewith) is then shaped to form a molded pulp. The molded pulp is then heated to achieve at least partial melting of the polymer, and subsequently cooled to solidify the polymer. When at least partially liquid, the polymer is in close contact with the cellulosic fibers, and this close contact is maintained during subsequent solidification, thereby bonding adjacent cellulosic fibers and / or agglomerates to adjacent polymers to form a polymer network.
[0047] Alternatively or additionally, the polymer may be provided as an aqueous dispersion or solution of the polymer in liquid or paste form. The aqueous dispersion may have a solids content of 10% w / w to 50% w / w, preferably 20% w / w to 40% w / w, or more preferably 25% w / w to 35% w / w. The solids content is the content of the aqueous dispersion consisting of the polymer. The aqueous dispersion or solution is mixed with cellulosic fibers (optionally in the presence of a surfactant). The cellulosic fibrous material (and the polymer mixed therewith) is then shaped to form a shaped pulp. The shaped pulp is then heated to achieve at least partial melting of the polymer, and subsequently cooled to solidify the polymer. Optionally, the cellulosic fibrous material is dried prior to shaping or during the heating step. When at least partially liquid, the polymer is in close contact with the cellulosic fibers, and this close contact is maintained during subsequent solidification, thereby bonding adjacent cellulosic fibers and / or agglomerates to adjacent polymers to form a polymer network. Cellulose fibers can be wetted or dry (i.e., wet pulp or dry molded pulp fluff), wherein if wetted cellulose fibers are used, a heating step removes water from them.
[0048] In a second embodiment, the method further includes providing a tactile layer, and the polymer is provided as a polymer layer situated between the cellulosic fibrous material and the tactile layer. The polymer layer and the tactile layer may be as described herein. Shaping the cellulosic material also includes shaping the polymer layer and the tactile layer to provide a layered structure. Heating and at least partially melting the polymer layer has the effect of laminating the tactile layer onto the formed pulp. The polymer layer may be in the form of a web or a film. The cellulosic fibers may be wetted or dry (i.e., wet pulp or dry molded pulp fibers), wherein if wetted cellulosic fibers are used, the heating step removes water from them. Preferably, if the polymer layer is a film, the cellulosic fibers are dry.
[0049] In another embodiment, the first and second embodiments of the methods disclosed herein may be combined. For example, a polymer (preferably in the form of powder or granules) is dispersed throughout a cellulosic fibrous material to provide a tactile layer, and a polymer layer is located between the cellulosic fibrous material and the tactile layer. The entire assembly is then integrally shaped and heated as described herein to form a molded pulp article comprising a polymer dispersed throughout the molded pulp and a polymer layer located between the molded pulp and the tactile layer.
[0050] In any of the foregoing methods, the heating step achieves at least partial melting of the polymer (whether in the form of powder, granules, aqueous dispersion, or layer) without damaging the forming pulp. Essentially any heating technique and temperature can be used to achieve at least partial melting of the polymer without damaging the pulp. The forming pulp and polymer can be heated to temperatures below 250°C, such as 50°C to 200°C, 100°C to 150°C, or about 120°C.
[0051] In any of the foregoing methods, the step of shaping the cellulosic fibrous material into molded pulp can be performed prior to the step of heating the molded pulp to achieve at least partial melting of the polymer. Alternatively, the shaping and heating steps can occur simultaneously (e.g., by thermoforming), which provides the benefit of compressing the cellulosic fibers while the polymer (whether in the form of a polymer dispersed throughout the pulp, a polymer layer, or a combination thereof) is at least partially liquid, thereby increasing their contact area and the robustness of the resulting molded pulp article.
[0052] Uses of molded pulp products
[0053] The molded pulp articles described herein are used for packaging edible products intended for human or animal consumption. Preferably, the molded pulp articles are in the form of partially open containers, through which the edible products are inserted. Once the molded pulp articles are filled, the opening is sealed, preferably with a polymer film, a removable cap (e.g., a screw cap), or foil (which may be tightly bonded foil or peelable foil intended for later removal).
[0054] A packaged edible product comprising molded pulp articles as described herein, at least partially filled with edible products intended for human or animal consumption.
[0055] Preferably, the edible product is a powder, gel, or coarsely ground food, and is selected from the list of: soluble coffee, nutritional compositions for infants, adults, or the elderly, soups, sweets or confectionery, chocolate products, dried animal products, and dairy products.
[0056] Example
[0057] Example 1—Polymer reinforcement in the form of polymer layers
[0058] Arrange the following materials into a series of layers:
[0059] -Dry the molded pulp fluff.
[0060] - A 100µm thick PHA membrane, and
[0061] - Paper weighing 20gsm.
[0062] The layered arrangement was subjected to a pressure of 500 MPa and a temperature of 125°C for 5 minutes to achieve the lamination of pulp fibers onto paper. The resulting structure is suitable for further shaping into molded pulp products and was found to be water-impermeable after both wetting and subsequent immersion.
[0063] Example 2—Polymer reinforcement in the form of a polymer dispersed throughout the pulp
[0064] Dry molded pulp fluff (50% to 90% by weight) and PHA polymer powder (10% to 50% by weight) are mixed. The mixture is placed in a mold, where it is pressed and heated to achieve close contact between the cellulose fibers and the polymer, and to form the molded pulp article.
[0065] Example 3—Physical Characterization of Molded Pulp Products
[0066] The molded pulp articles of the present invention, which include polymer reinforcements, are compared with unreinforced molded pulp articles.
[0067] In the first test, water was applied to the surface of each article. Unreinforced molded pulp articles ( Figure 3A It rapidly absorbs water and swells, losing its cohesive force. In contrast, water droplets remain in the molded pulp articles of the present invention, which include polymer reinforcements. Figure 3B The molded pulp article according to the invention has improved water resistance compared to conventionally molded pulp articles.
[0068] In the second test, molded pulp articles with and without polymer reinforcement were subjected to tensile strength tests, the results of which are shown in Figure 4. This test demonstrates that the molded pulp articles according to the invention exhibit improved tensile strength compared to conventionally molded pulp articles.
Claims
1. A molded pulp article, the molded pulp article comprising: Formed pulp, the formed pulp comprising cellulose fibers; and Polymer reinforcement.
2. The molded pulp article of claim 1, wherein the polymer reinforcement comprises a polymer dispersed throughout the molded pulp.
3. The molded pulp article according to claim 2, wherein the polymer accounts for up to 50% by weight of the total mass of the molded pulp and the polymer reinforcement, optionally between 1% by weight and 50% by weight, optionally between 10% by weight and 40% by weight, optionally between 20% by weight and 30% by weight, optionally about 30% by weight.
4. The molded pulp article according to any one of the preceding claims, wherein the molded pulp article further comprises a tactile layer, and the polymer reinforcement comprises a polymer layer located between the molded pulp and the tactile layer.
5. The molded pulp article according to claim 4, wherein the polymer layer is a web or film, optionally having a thickness of 1µm to 200µm, optionally 10µm to 150µm, more preferably 20µm to 120µm, further preferably 30µm to 80µm, even more preferably 40µm to 60µm, and most preferably about 50µm.
6. The molded pulp article according to claim 4 or claim 5, wherein the tactile layer has a paper feel, optionally, the tactile layer is selected from thin pulp layers, paperboard and paper layers.
7. The molded pulp article according to any one of claims 4 to 6, wherein the tactile layer has a weight of 5 gsm to 150 gsm, optionally 10 gsm to 100 gsm, optionally 15 gsm to 50 gsm, optionally about 20 gsm.
8. The molded pulp article according to any one of claims 1 to 7, wherein the polymer is a biodegradable polymer, optionally selected from polylactic acid (PLA), polyvinyl alcohol (PVOH), polyhydroxyalkanoate (PHA), polycaprolactone (PCL), polyglycolic acid (PGA), butene glycol (BVOH), ethylene glycol (EVOH), poly(butylene succinate-co-butylene adipate) (PBSA), polybutylene terephthalate (PBAT), lignin, polyhydroxylated polysaccharides (such as starch, cellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose), proteins (such as casein, zein, soy protein, silk protein), and combinations thereof.
9. A method for producing molded pulp articles, the method comprising: a) Provides cellulose-based fiber materials; b) Provide polymers; c) Forming the cellulose-based fibrous material into shaped pulp; d) Heating the forming pulp to achieve at least partial melting of the polymer; as well as e) Cool the formed pulp to cure the polymer.
10. The method of claim 9, wherein the cellulose-based fibrous material and the polymer are provided as a mixture, wherein the polymer is dispersed throughout the cellulose-based fibrous material.
11. The method of claim 10, wherein the polymer is provided in the form of powder and / or granules, and the polymer is dispersed throughout the cellulose fibrous material by mixing the cellulose fibers with the powder and / or granules.
12. The method of claim 10, wherein the polymer is dispersed throughout the cellulose fibrous material by optionally mixing the cellulose fibers with an aqueous dispersion of the polymer in the presence of a surfactant.
13. The method according to any one of claims 9 to 12, wherein the method further comprises the step of providing a tactile layer, and wherein the polymer is provided as a polymer layer located between the cellulose-based fibrous material and the tactile layer.
14. The method according to any one of claims 9 to 13, wherein step c) occurs before step d), or wherein steps c) and d) occur simultaneously.
15. The method according to any one of claims 9 to 14, wherein step c) comprises thermoforming.
16. The method according to any one of claims 9 to 15, wherein step d) comprises heating the formed pulp to a temperature below 250°C, preferably between 50°C and 200°C, more preferably between 100°C and 150°C, and most preferably about 120°C.
17. Use of the molded pulp article according to any one of claims 1 to 8 for packaging edible products for human or animal consumption.
18. A packaged edible product comprising a molded pulp article according to any one of claims 1 to 8, the molded pulp article being at least partially filled with an edible product for human or animal consumption.