Degradable valve bag and preparation method thereof

Abstract

The invention relates to the technical field of packaging bags, in particular to a degradable valve bag and a preparation method thereof. The preparation method of the valve bag comprises the four steps of weaving layer preparation, film covering layer preparation, cloth cutting and film covering and forming. The starch-based degradable plastic is adopted to replace an original PE film to serve as the film coating layer of the valve bag, and the prepared valve bag shows good degradation performance in the natural environment, does not pollute the environment for a long time, relieves the environmental pressure and meanwhile has certain mechanical strength. In addition, the preparation method disclosed by the invention is low in manufacturing cost, simple in preparation process and easy to operate.

Description

Technical Field

[0001] The present invention relates to the technical field of packaging bags, in particular to a degradable valve bag and a preparation method thereof. Background Art

[0002] Powder packaging primarily relies on manual labor, and valve bags are a type of bag designed for high-speed, quantitative filling of ultrafine powders such as chemical raw materials, flour, and fertilizer. Currently available valve bags include kraft paper valve bags, woven bags, PE valve bags, and composite valve bags. In valve bag applications, the valve opening is rolled into a cylindrical shape and fixed in place, through which material is filled. Because the valve opening is connected to the interior of the bag, any bumps during transportation can cause powder to overflow from the damaged valve opening. This can result in dust, high temperatures, and noise on the production line, seriously threatening workers' physical and mental health and placing significant operational and social pressure on the powder packaging industry.

[0003] Currently, most valve bags use PE film as the middle layer, which is not easily degraded. Discarded valve bags put a great deal of pressure on the environment. Therefore, to prevent dust from flying in the production workshop and improve the living environment, it is urgent to develop a valve bag that is both breathable and sealed, not easily damaged, has high load-bearing capacity, and is easily degradable. Summary of the Invention

[0004] In response to the problems existing in the background technology, the present invention provides a degradable valve bag and a preparation method thereof. The prepared valve bag can be degraded in a short time, and the manufacturing process is simple and the raw materials are cheap and easily available.

[0005] The following technical solutions are used:

[0006] A method for preparing a degradable valve bag comprises the following steps:

[0007] Step (a) Preparation of Braided Layer: Glycol-lactide copolymer, heavy calcium carbonate, polypropylene powder, liquid paraffin, and lubricant are mixed and melt-extruded to obtain embryonic yarns, the embryonic yarns are stretched and shaped to obtain shaped flat yarns, and the flat yarns are woven to obtain a woven fabric as the braided layer;

[0008] Step (b) Preparation of the film layer: weigh the raw materials in proportion, add them into a high-speed mixer, heat and gelatinize them, and then extrude them into granules. The granules are then injected into a hot press and hot-pressed into a film;

[0009] Step (c) Splitting and Laminating: The laminating layer obtained in step (b) is covered on the woven layer using ultrasonic welding technology to obtain a valve bag making material;

[0010] Step (d) forming: using valve bag making equipment to roll, slit, trim corners and heat-seal the bag-making material obtained in step (c) to prepare a degradable valve bag.

[0011] Preferably, the specific steps of preparing the braided layer in step (a) are: weighing 60% to 72% of glycolide-lactide copolymer, 15% to 21% of heavy calcium carbonate, 3% to 6% of polypropylene powder, 1% to 3% of liquid paraffin, and 1% to 2% of lubricant, mixing, heating, melting and extruding to obtain an extruded sheet, cooling and cutting into embryonic yarns, stretching the embryonic yarns at 60° C. to 120° C., and then heat-setting and cold-setting to obtain shaped flat yarns, and weaving the flat yarns to obtain a woven cloth as the braided layer.

[0012] More preferably, the lubricant in step (a) is selected from one or more of stearic acid, butyl stearate, oleamide, and ethylene bisstearamide.

[0013] Preferably, the preparation steps of the coating layer in step (b) are as follows: corn starch, polyvinyl alcohol and plasticizer are added to a high-speed mixer in proportion, heated and gelatinized for 20 to 25 minutes under nitrogen protection, and then the viscous polymer is added to a twin-screw internal mixer, extruded into granules, and the granules are hot-pressed at 150°C and 15 MPa to obtain the coating material.

[0014] More preferably, the plasticizer is one or more of glycerol, phthalate, dioctyl phthalate, and diisodecyl phthalate.

[0015] More preferably, the extrusion granulation conditions of the twin-screw internal mixer are: a rotation speed of 50 rpm and a temperature of 120° C. to 130° C.

[0016] Further preferably, the membrane material prepared in step (b) has a thickness of about 1.0±0.05 mm.

[0017] Compared with the prior art, the present invention has the following technical advantages:

[0018] This invention uses starch-based biodegradable plastic instead of conventional PE film as the film coating for valve bags. The resulting valve bags exhibit excellent degradation properties and a short degradation cycle, capable of complete degradation within five months. They also possess excellent mechanical properties that meet required standards. Furthermore, the process described in this invention offers low manufacturing costs, using inexpensive, renewable raw materials that are fully biodegradable, and a production cost that is essentially comparable to that of conventional valve bags. Furthermore, the preparation process is simple and easy to operate. DETAILED DESCRIPTION

[0019] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and are therefore only used as examples and cannot be used to limit the scope of protection of the present invention.

[0020] It should be noted that the experimental methods used in the examples are conventional methods unless otherwise specified; the materials, reagents, etc. used are all available from commercial channels unless otherwise specified.

[0021] In the present invention, unless otherwise specified, all "parts" and percentages (%) refer to percentages by weight.

[0022] In the present invention, unless otherwise specified, the sum of all percentages in all compositions is 100%.

[0023] In the present invention, unless otherwise specified, the numerical range "a-b" is an abbreviation for any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is merely an abbreviation for these numerical combinations.

[0024] In the present invention, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution.

[0025] In the present invention, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially; for example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially; for example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0026] In the present invention, unless otherwise specified, the specific numerical values and specific substances in the embodiments of the present invention may be combined with other features of the description part of the present invention; for example, if the specification mentions that the reaction temperature is 10-100°C, and the embodiment mentions that the reaction temperature is 20°C, then it can be considered that the present invention has specifically disclosed the range of 10-20°C, or the range of 20-100°C, and this range can be combined with other features of the description part to form a new technical solution.

[0027] Example 1:

[0028] 70% glycolide-lactide copolymer, 20% ground calcium carbonate, 6% polypropylene powder, 2% liquid paraffin, and 2% stearic acid were weighed, mixed, heated, and melt-extruded to produce an extruded sheet. After cooling, the sheet was cut into filaments, which were then stretched at 100°C, heat-set, and cold-set to produce flat yarns. These flat yarns were then woven into a woven fabric as the woven layer. 85% corn starch, 12% polyvinyl alcohol, and 3% glycerol were added to a high-speed blender and heated under nitrogen for gelatinization for 25 minutes. The viscous polymer was then added to a twin-screw internal mixer and extruded into pellets at 50 rpm and 130°C. The pellets were then hot-pressed at 150°C and 15 MPa to produce a coating material. The resulting coating layer was ultrasonically welded onto the woven layer to produce valve bag material. The resulting material was then rolled, slit, trimmed, and heat-sealed using valve bag making equipment to produce biodegradable valve bags.

[0029] Example 2:

[0030] 71% glycolide-lactide copolymer, 21% ground calcium carbonate, 5% polypropylene powder, 2% liquid paraffin, and 1% stearic acid were weighed, mixed, heated, melt-extruded, and extruded to produce an extruded sheet. After cooling, the sheet was cut into filaments, which were then stretched at 120°C, heat-set, and cold-set to produce flat yarns. These flat yarns were then woven to form a woven fabric as the woven layer. 85% corn starch, 12% polyvinyl alcohol, and 3% glycerol were added to a high-speed blender and heated under nitrogen for gelatinization for 25 minutes. The viscous polymer was then added to a twin-screw internal mixer and extruded at 50 rpm and 130°C to form pellets. The pellets were then hot-pressed at 150°C and 15 MPa to produce a coating material. The resulting coating layer was ultrasonically welded onto the woven layer to produce valve bag material. The resulting material was then rolled, slit, corner-cut, and heat-sealed using valve bag making equipment to produce biodegradable valve bags.

[0031] Example 3:

[0032] 71% glycolide-lactide copolymer, 21% ground calcium carbonate, 5% polypropylene powder, 2% liquid paraffin, and 1% stearic acid were weighed, mixed, heated, and melt-extruded to produce an extruded sheet. After cooling, the sheet was cut into filaments, which were then stretched at 100°C, heat-set, and cold-set to produce flat yarns. These flat yarns were then woven into a woven fabric as the woven layer. 79% corn starch, 14% polyvinyl alcohol, and 7% glycerol were added to a high-speed blender and heated under nitrogen for gelatinization for 25 minutes. The viscous polymer was then added to a twin-screw internal mixer and extruded into pellets at 50 rpm and 120°C. The pellets were then hot-pressed at 150°C and 15 MPa to produce a coating material. The resulting coating layer was ultrasonically welded onto the woven layer to produce valve bag material. The resulting material was then rolled, slit, corner-cut, and heat-sealed using valve bag making equipment to produce biodegradable valve bags.

[0033] Example 4:

[0034] 68% glycolide-lactide copolymer, 21% ground calcium carbonate, 6% polypropylene powder, 3% liquid paraffin, and 2% stearic acid were weighed, mixed, heated, and melt-extruded to produce an extruded sheet. After cooling, the sheet was cut into filaments, which were then stretched at 100°C, heat-set, and cold-set to produce flat yarns. These flat yarns were then woven into a woven fabric as the woven layer. 85% corn starch, 12% polyvinyl alcohol, and 3% glycerol were added to a high-speed blender and heated under nitrogen for gelatinization for 25 minutes. The viscous polymer was then added to a twin-screw internal mixer and extruded into pellets at 50 rpm and 130°C. The pellets were then hot-pressed at 150°C and 15 MPa to produce a coating material. The resulting coating layer was ultrasonically welded onto the woven layer to produce valve bag material. The resulting material was then rolled, slit, trimmed, and heat-sealed using valve bag making equipment to produce biodegradable valve bags.

[0035] Embodiment 5:

[0036] 68% glycolide-lactide copolymer, 21% ground calcium carbonate, 6% polypropylene powder, 3% liquid paraffin, and 2% stearic acid were weighed, mixed, heated, melt-extruded, and extruded to produce an extruded sheet. After cooling, the sheet was cut into filaments, which were then stretched at 60°C, heat-set, and cold-set to produce flat yarns. These flat yarns were then woven to form a woven fabric as the woven layer. 85% corn starch, 12% polyvinyl alcohol, and 3% glycerol were added to a high-speed blender and heated under nitrogen for gelatinization for 25 minutes. The viscous polymer was then added to a twin-screw internal mixer and extruded at 50 rpm and 120°C to form pellets. The pellets were then hot-pressed at 150°C and 15 MPa to produce a coating material. The resulting coating layer was ultrasonically welded onto the woven layer to produce valve bag material. The resulting material was then rolled, slit, corner-cut, and heat-sealed using valve bag making equipment to produce biodegradable valve bags.

[0037] Example 6:

[0038] Mechanical properties

[0039] The valve bags prepared in Examples 1 to 5 were cut into standard dumbbell-shaped picks according to GB / T1040.3-2006, and the tensile strength was tested using a universal tensile testing machine. The test results are shown in Table 1.

[0040] Table 1

[0041]

[0042]

[0043] Embodiment seven:

[0044] In vitro degradation performance

[0045] The valve bags prepared in Examples 1 to 5 were cut into pieces with an area of 2×2 cm. 2 The initial mass N1 of the membrane was accurately weighed using a 1 / 10,000 balance, and then immersed in sterile simulated body fluid to simulate in vitro degradation in a biological incubator. The degradation temperature was set to 37±0.1℃. The membrane was taken out at regular intervals, weighed and the mass of each membrane was recorded, recorded as N2. The mass loss fraction was calculated using formula 1. The results are shown in Table 2, which was used to evaluate the degradation of the material.

[0046] Formula 1: (N1-N2) / N1×100%

[0047] Table 2

[0048]

[0049] From the above simulated degradation results, it can be inferred that the material can be degraded within five months with a relatively fast degradation rate. It is an environmentally friendly material, and the overall tensile strength of the material meets the standards.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A method for preparing a degradable valve bag, comprising the following steps: Step (a) Preparation of Braided Layer: Glycol-lactide copolymer, heavy calcium carbonate, polypropylene powder, liquid paraffin, and lubricant are mixed and melt-extruded to obtain embryonic yarns, the embryonic yarns are stretched and shaped to obtain shaped flat yarns, and the flat yarns are woven to obtain a woven fabric as the braided layer; Step (b) Preparation of the film layer: weigh the raw materials in proportion, add them into a high-speed mixer, heat and gelatinize them, and then extrude them into granules. The granules are then injected into a hot press and hot-pressed into a film; Step (c) Splitting and Laminating: The laminating layer obtained in step (b) is covered on the woven layer using ultrasonic welding technology to obtain a valve bag making material; Step (d) forming: using valve bag making equipment to roll, slit, trim corners and heat-seal the bag-making material obtained in step (c) to prepare a degradable valve bag.

2. The method for preparing a degradable valve bag according to claim 1, characterized in that: The specific steps of preparing the braided layer in step (a) are as follows: 60% to 72% of glycolide-lactide copolymer, 15% to 21% of heavy calcium carbonate, 3% to 6% of polypropylene powder, 1% to 3% of liquid paraffin, and 1% to 2% of lubricant are weighed, mixed, heated, melted, and extruded to obtain an extruded sheet, which is then cooled and cut into embryonic yarns, stretched at 60° C. to 120° C., and then heat-set and cold-set to obtain shaped flat yarns, which are then braided to obtain a woven cloth as the braided layer.

3. The method for preparing a degradable valve bag according to claim 1, characterized in that: The lubricant in step (a) is selected from one or more of stearic acid, butyl stearate, oleamide, and ethylene bisstearamide.

4. The method for preparing a degradable valve bag according to claim 1, characterized in that: The preparation steps of the coating layer in step (b) are as follows: corn starch, polyvinyl alcohol and plasticizer are added to a high-speed mixer in proportion, heated and gelatinized for 20 to 25 minutes under nitrogen protection, and then the viscous polymer is added to a twin-screw internal mixer, extruded into granules, and the granules are hot-pressed at 150°C and 15 MPa to obtain the coating material.

5. The method for preparing a degradable valve bag according to claim 4, characterized in that: The plasticizer is one or more of propylene glycol, phthalate, dioctyl phthalate and diisodecyl phthalate.

6. The method for preparing a degradable valve bag according to claim 4, characterized in that: The extrusion granulation conditions of the twin-screw internal mixer are: rotation speed 50 rpm, temperature 120°C to 130°C.

7. The method for preparing a degradable valve bag according to claim 4, characterized in that: The thickness of the membrane material prepared in step (b) is about 1.0±0.05 mm.

8. A degradable valve bag, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

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