Biodegradable composite material, preparation method and electrochemical aluminum film

Abstract

The invention discloses a biodegradable composite material, which is prepared from the following raw materials in percentage by weight: 60 to 78 percent of polylactic acid, 20 to 30 percent of flexibilizer, 1 to 10 percent of transparent inorganic matter and 0.1 to 0.5 percent of cellulose. According to the invention, the block polyether amide resin is adopted as the flexibilizer and acts together with the PLA resin, and then the inorganic substance zinc sulfide with high transparency is added, so that the obtained composite material has good tensile toughness and excellent heat resistance. Meanwhile, the transparency and the puncture resistance of the biodegradable composite material film are improved, and the tensile toughness and the heat resistance are obviously improved. While being degradable, the adhesive force is good, the pattern integrity is high, the slitting performance is good, and the holographic hot stamping performance of the alumite film is not affected.

Description

Technical Field

[0001] The invention relates to the field of printing, and in particular to a biodegradable composite material and a preparation method thereof, and an electrochemical aluminum film. Background Art

[0002] Holographic hot stamping technology is widely welcomed due to its excellent surface decoration effect and is widely used in a variety of outer packaging materials. The electroplated aluminum film in the holographic hot stamping process is mostly made of PET material, which is not degradable. The electroplated aluminum waste film produced in the hot stamping process has caused serious garbage disposal problems. It is mostly treated by incineration, which will produce environmental pollutants such as dioxins. Therefore, it is very important to develop a biodegradable electroplated aluminum base film that will not affect the holographic hot stamping effect.

[0003] Chinese invention patent CN112829489B discloses a UV flash three-dimensional hot stamping packaging box printing process, which selects components such as hydrogen silicone oil, vinyl silicone oil, perfluoroalkylethylene and diethylaminoethyl methacrylate, and undergoes silylation under the action of a platinum catalyst (chloroplatinic acid-isopropyl alcohol mixed solution), thereby forming a cross-linked organic silicone release layer that has excellent release and demoulding effects when used, but does not have a degradation effect. Chinese utility model patent CN217778169U discloses a holographic true color hot stamping film, on which a release layer, an information layer, a color layer, an aluminum plating layer and a hot stamping adhesive layer are sequentially arranged, which can achieve good and accurate true color overprinting, but does not have degradation performance. Summary of the invention

[0004] In order to develop a biodegradable electrochemical aluminum base film that does not affect the holographic hot stamping effect, the first aspect of the present invention provides a biodegradable composite material, the raw materials for preparation of which include 60-78% polylactic acid, 20-30% toughening agent, 1-10% transparent inorganic matter, and 0.1-0.5% cellulose in weight percentage.

[0005] As a preferred embodiment, the melt index of the polylactic acid at 190° C. and 2.16 kg is 1-6 g / 10 min.

[0006] As a preferred embodiment, the toughening agent is a block polyetheramide resin.

[0007] As a preferred embodiment, the cellulose is ethyl cellulose, and the mass fraction of ethoxy groups in the ethyl cellulose is 44-47.9%.

[0008] As a preferred embodiment, the viscosity of the ethyl cellulose at 25° C. is 3-5.5 mPa·s.

[0009] As a preferred embodiment, the transparent inorganic substance is selected from at least one of sodium oxide, silicon carbide, titanium oxide, zinc oxide, zinc sulfide, boron nitride and aluminum oxide.

[0010] As a preferred embodiment, the transparent inorganic substance is zinc sulfide.

[0011] The inventors found during the experiment that after polylactic acid was blended with inorganic materials such as nano-silica and graphene, the tensile toughness and heat resistance of the prepared blended material were significantly improved, but the transparency of the composite material was seriously affected and could not meet the requirements as a printing substrate.

[0012] The inventors found in the experimental process that the composite material obtained by using block polyetheramide resin as a toughening agent, acting together with PLA resin, and then adding high-transparency inorganic zinc sulfide, has good tensile toughness and heat resistance. The possible reason is speculated to be: using block polyetheramide resin as a toughening agent, PLA polylactic acid and block polyetheramide resin act together, and the polyamide segment and polyether segment included therein can make the polymer chain segment softer, improve the toughness of the polymer, and due to the presence of the polyamide segment, the heat resistance of the polymer will not be reduced. Compared with the toughening modification of polylactic acid and petroleum-based polymer materials, it will affect the degradation performance of PLA. However, the toughening modification of polylactic acid and acid ester biodegradable polymer materials has a large deformation under high temperature conditions and cannot meet the requirements as a printing substrate.

[0013] However, the applicant further discovered that the toughness improvement effect of a single block polyetheramide resin and a PLA resin combination after blending is not particularly high. The reason may be that the block polyetheramide resin and the PLA resin are not compatible enough to form a "sea-island" structure of a heterogeneous system, which makes the toughness improvement effect less obvious. By introducing ethyl cellulose, the crystallinity of the polymer is changed, the regular folding and crystallization of the PLA molecular chain is restricted, and the crystallinity of the system is promoted, thereby having good mechanical strength.

[0014] A second aspect of the present invention provides a method for preparing a biodegradable composite material, comprising the following steps:

[0015] S1 Drying: Place polylactic acid, toughening agent, transparent inorganic substance and cellulose in a vacuum drying oven and dry at 70-90°C for 10-15h to remove moisture and small molecule residues;

[0016] S2 melt extrusion: add the dried polylactic acid, toughening agent, transparent inorganic substance and cellulose into a twin-screw extruder according to weight ratio for melt blending, the temperature distribution from the feed section to the die is 140-165°C, extrusion water-cooled pelletizing and drying to obtain pellets;

[0017] S3 film blowing: adding the pellets into the film blowing machine for film blowing processing to obtain a biodegradable composite material.

[0018] As a preferred embodiment, the screw speed of the twin-screw extruder is 20-30r / min.

[0019] As a preferred implementation, the screw speed of the twin-screw extruder is 25 r / min.

[0020] As a preferred embodiment, the biodegradable composite film has a thickness of 13-15 μm.

[0021] The third aspect of the present invention provides an electrochemical aluminum film, including a biodegradable composite material prepared by the above method.

[0022] As a preferred embodiment, the biodegradable composite material is a film structure.

[0023] As a preferred embodiment, the structure of the electrochemical aluminum film includes, from bottom to top, a biodegradable composite material layer, an electrochemical aluminum color layer, a holographic laser layer, an electroplating layer, and an electrochemical aluminum glue layer, and each layer is fixedly connected.

[0024] As a preferred embodiment, the raw materials for preparing the electrochemical aluminum color layer include an acrylic resin solution mixture, a dye, and a leveling agent; the raw materials for preparing the electrochemical aluminum glue layer include electrochemical aluminum glue and fumed silica.

[0025] As a preferred embodiment, in parts by weight, the raw materials for preparing the electrochemical aluminum color layer include 5-10 parts of an acrylic resin solution mixture, 0.1-0.5 parts of a dye, and 0.01-0.1 parts of a leveling agent; the raw materials for preparing the electrochemical aluminum glue layer include 5-10 parts of an electrochemical aluminum glue and 0.5-5 parts of fumed silica.

[0026] As a preferred embodiment, in parts by weight, the raw materials for preparing the electrochemical aluminum color layer include 7.2 parts of an acrylic resin solution mixture, 0.24 parts of a dye, and 0.05 parts of a leveling agent; the raw materials for preparing the electrochemical aluminum glue layer include 8.5 parts of electrochemical aluminum glue and 1.01 parts of fumed silica.

[0027] A fourth aspect of the present invention provides a method for preparing an electrochemical aluminum film, comprising the following steps:

[0028] S1 pre-prepare electrochemical aluminum color layer coating and electrochemical aluminum glue layer coating;

[0029] S2: coating an electrochemical aluminum color layer coating on the biodegradable composite material, heating and drying in an oven channel to solidify the coating, thereby obtaining an electrochemical aluminum color layer;

[0030] S3 holographically molds a pattern with laser holographic effect on the electroplated aluminum color layer to obtain a holographic laser layer;

[0031] S4 performs vacuum electroplating on the holographic laser layer to obtain an electroplated layer;

[0032] S5: coating an electroplated aluminum adhesive layer on the electroplated layer, heating and drying and curing in an oven channel to obtain an electroplated aluminum film.

[0033] As a preferred embodiment, the preparation method of the electrochemical aluminum color layer coating comprises the following steps: dissolving the dye in an acrylic resin solution mixture and adding a leveling agent, dispersing for 20-40 minutes and filtering with a 300-mesh filter bag to obtain the electrochemical aluminum color layer coating.

[0034] As a preferred embodiment, the preparation method of the electrochemical aluminum glue layer coating comprises the following steps: adding fumed silica to the electrochemical aluminum glue water, dispersing for 40-50 minutes, and filtering with a 180-mesh filter bag to obtain the electrochemical aluminum glue layer coating.

[0035] As a preferred embodiment, in step S2, the oven channel temperature is set to 75°C-95°C-115°C-118°C-158°C-95°C, and the coating speed is 120-130 m / min. Preferably, the coating speed is 128 m / min.

[0036] As a preferred embodiment, the pressure of the holographic molding in step S3 is 5-15 kg / m 2 The temperature of holographic molding is 160-170℃, and the running speed of holographic molding is 60-70m / min.

[0037] As a preferred embodiment, the pressure of the holographic molding in step S3 is 10 kg / m 2 The temperature of holographic molding is 165°C, and the running speed of holographic molding is 65m / min.

[0038] As a preferred embodiment, the vacuum degree of the vacuum plating in step S4 is 10 -3 ~10 -5 Pa, the aluminum plating speed of vacuum electroplating is 100-120m / min.

[0039] As a preferred embodiment, the vacuum degree of the vacuum plating in step S4 is 10 -3 Pa, the aluminum plating speed of vacuum electroplating is 110m / min.

[0040] As a preferred embodiment, in step S5, the oven channel temperature is set to 90°C-115°C-135°C-135°C-115°C, and the coating speed is 80-100 m / min. Preferably, the coating speed is 90 m / min.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The biodegradable composite material of the present invention uses a block polyetheramide resin as a toughening agent to act together with a PLA resin, and then adds a high-transparency inorganic zinc sulfide. The obtained composite material has good tensile toughness and excellent heat resistance.

[0043] (2) The biodegradable composite material of the present invention can improve the compatibility of the block polyetheramide resin and the PLA resin combination by introducing ethyl cellulose, further promoting the crystallinity of the system, thereby having good mechanical strength.

[0044] (3) The biodegradable composite material of the present invention improves the transparency and puncture resistance of the biodegradable composite film by introducing transparent zinc sulfide, and the tensile toughness and heat resistance are significantly improved.

[0045] (4) The electrochemical aluminum film of the present invention uses a biodegradable composite material film as a base film to achieve the degradable performance of the electrochemical aluminum film and reduce environmental problems in the production process.

[0046] (5) The electrochemical aluminum film of the present invention adopts a biodegradable composite material. While being biodegradable, it has good adhesion, high pattern integrity, and good slitting performance, and does not affect the holographic hot stamping performance of the electrochemical aluminum film. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a production process flow chart for preparing electrochemical aluminum film in Example 6 of the present invention. DETAILED DESCRIPTION

[0048] Example 1

[0049] A biodegradable composite material, the preparation raw materials of which include 70% polylactic acid, 24.85% toughening agent, 5% transparent inorganic matter and 0.15% cellulose in percentage by weight.

[0050] The polylactic acid has a melt index of 4 g / 10 min at 190° C. and 2.16 kg and is purchased from Anhui Fengyuan Biotechnology Co., Ltd. with a brand name of FY804.

[0051] The toughening agent is a block polyetheramide resin purchased from Arkema with a brand name of MH2030.

[0052] The transparent inorganic substance is zinc sulfide, which is purchased from Tianjin Damao Chemical Reagent Factory.

[0053] The cellulose is ethyl cellulose, the mass fraction of ethoxy groups in the ethyl cellulose is 44-47.9%, the viscosity of the ethyl cellulose at 25° C. is 3-5.5 mPa·s, and the ethyl cellulose is purchased from Shanghai Helisite Chemical Industry with a brand name of K4.

[0054] A method for preparing a biodegradable composite material comprises the following steps:

[0055] S1 Drying: PLA, toughening agent, transparent inorganic substance and cellulose are placed in a vacuum drying oven and dried at 80°C for 12 hours to remove moisture and small molecule residues;

[0056] S2 melt extrusion: add the dried polylactic acid, toughening agent, transparent inorganic substance and cellulose into a twin-screw extruder according to weight ratio for melt blending, the temperature distribution from the feed section to the die is 140-165°C, extrusion water-cooled pelletizing and drying to obtain pellets;

[0057] S3 film blowing: adding the pellets into the film blowing machine for film blowing processing to obtain a biodegradable composite material.

[0058] The screw speed of the twin-screw extruder is 25 r / min.

[0059] The biodegradable composite film has a thickness of 14 μm.

[0060] The prepared biodegradable composite material is a film structure.

[0061] Comparative Example 1

[0062] A PLA film with a thickness of 15 μm was purchased from Changding New Materials (Kunshan) Co., Ltd., brand: PLA biodegradable functional film.

[0063] Comparative Example 2

[0064] A PLA blended modified film with a thickness of 15 μm, purchased from Xiamen Changsu Industrial Co., Ltd., brand: Baienli ECP Standard.

[0065] Comparative Example 3

[0066] A PET biaxially oriented film with a thickness of 12 μm was purchased from Foshan DuPont Hongji Film Co., Ltd. with the brand name PET1310.

[0067] Application Examples

[0068] An electrochemical aluminum film has a structure which, from bottom to top, comprises the above-mentioned thin film, an electrochemical aluminum color layer, a holographic laser layer, an electroplating layer, and an electrochemical aluminum glue layer.

[0069] The raw materials for preparation are shown in Table 1 below in parts by weight:

[0070] Table 1

[0071]

[0072] The acrylic resin solution mixture was purchased from Jiangxi Aotelai New Materials Co., Ltd., with the brand name AT-605;

[0073] The electrochemical aluminum glue was purchased from Jiangxi Aotelai New Materials Co., Ltd., with the brand name AT-618;

[0074] The dye was purchased from Wuxi Minghui and its brand name is Solvent Yellow 21;

[0075] The leveling agent was purchased from BYK Chemicals, with the brand name BYK333;

[0076] The fumed silica was purchased from Evonik of Germany with a grade of 622.

[0077] A method for preparing an electrochemical aluminum film comprises the following steps:

[0078] S1 pre-prepare electrochemical aluminum color layer coating and electrochemical aluminum glue layer coating;

[0079] S2: coating an electrochemical aluminum color layer coating on the biodegradable composite material film, heating and drying and curing in an oven channel to obtain an electrochemical aluminum color layer;

[0080] S3 holographically molds a pattern with laser holographic effect on the electroplated aluminum color layer to obtain a holographic laser layer;

[0081] S4 performs vacuum electroplating on the holographic laser layer to obtain an electroplated layer;

[0082] S5: coating an electroplated aluminum adhesive layer on the electroplated layer, heating and drying and curing in an oven channel to obtain an electroplated aluminum film.

[0083] The preparation method of the electrochemical aluminum color layer coating comprises the following steps: dissolving the dye in an acrylic resin solution mixture and adding a leveling agent, dispersing for 30 minutes, and filtering with a 300-mesh filter bag to obtain the electrochemical aluminum color layer coating.

[0084] The preparation method of the electrochemical aluminum glue layer coating comprises the following steps: adding fumed silicon dioxide into the electrochemical aluminum glue water, dispersing for 45 minutes and filtering with a 180-mesh filter bag to obtain the electrochemical aluminum glue layer coating.

[0085] In step S2, the oven channel temperature is set to 75°C-95°C-115°C-118°C-158°C-95°C, and the coating speed is 128m / min.

[0086] The holographic molding pressure in step S3 is 10 kg / m 2 The temperature of holographic molding is 165°C, and the running speed of holographic molding is 65m / min.

[0087] The vacuum degree of the vacuum plating in step S4 is 10 -3 Pa, the aluminum plating speed of vacuum electroplating is 110m / min.

[0088] In step S5, the oven channel temperature is set to 90°C-115°C-135°C-135°C-115°C, and the coating speed is 90m / min.

[0089] Performance Testing

[0090] 1. Tensile properties: The films of Example 1 and Comparative Examples 1-3 were placed in the fixture of a tensile testing machine, and then tensile force was applied to stretch the films until they broke.

[0091] 2. Biodegradation rate: The films of Example 1 and Comparative Examples 1-3 were placed in a composting environment with a humidity of 50%-65%, a temperature of 25°C-65°C, oxygen supply, and a carbon-nitrogen ratio of (25-30):1. The weight change of the samples was analyzed after 8 weeks. Degradation rate = (m 0 -m) / m 0 ×100%; m: sample weight after 8 weeks; m 0 : Sample weight before degradation.

[0092] 3. Light transmittance:

[0093] According to the national standard "GB / T 2410-2008" transparency and haze test method, the light emitted by the light source of the light transmittance / haze tester (WGT-S) is transmitted through the sample. The instrument measures the difference between the light transmitted through the material and the light emitted by the light source to determine the light transmittance of the sample. Light transmittance = (light transmitted through the material / light emitted by the light source) × 100%

[0094] The test results are shown in Table 2.

[0095] Table 2

[0096]

[0097] Conclusion: The tensile properties of the biodegradable composite film of Example 1 are much better than those of pure PLA film and commercially available PLA blended modified film, and slightly lower than those of the PET film used for traditional electroplated aluminum, meeting the tensile strength requirements for holographic electroplated aluminum base films. The light transmittance of Example 1 is much better than that of pure PLA film and commercially available PLA blended modified film, and slightly lower than those of the PET film used for traditional electroplated aluminum, meeting the light transmittance requirements for holographic electroplated aluminum base films. The biodegradability of Example 1 is better than that of commercially available PLA blended modified film, slightly worse than that of pure PLA film, and much better than that of the PET film used for traditional holographic electroplated aluminum, meeting the biodegradability requirements.

[0098] 4. Tensile properties: The electrochemical aluminum films of Application Examples 1-8 were placed in the fixture of a tensile testing machine, and then tensile force was applied to stretch the electrochemical aluminum films until they broke.

[0099] 5. Biodegradation rate: The electrochemical aluminum films of application examples 1-8 were placed in a composting environment with a humidity of 50%-65%, a temperature of 25°C-65°C, oxygen supply, and a carbon-nitrogen ratio of (25-30):1 in a ventilated environment. After 8 weeks, the weight change of the samples was analyzed. Degradation rate = (m 0 -m) / m 0 ×100%; m: sample weight after 8 weeks; m 0 : Sample weight before degradation.

[0100] 6. Adhesion: After pressing the 3M transparent tape on the side of the sample containing the electroplated aluminum coating, pull the tape apart in a direction perpendicular to the sample to completely separate the tape and the sample, and observe whether there is any shedding. Level 1 means no shedding, level 2 means slight holes, level 3 means increased holes and slight shedding in pieces, and level 4 means increased shedding in pieces.

[0101] 7. Pattern integrity: Observe the integrity of the pattern on the sample surface to see if there is any discoloration or dullness. If the pattern is complete and no discoloration occurs, the color brightness level is O, otherwise it is X.

[0102] 8. Cutting property: observe whether there are jagged edges on the pattern edge of the sample surface, whether the edge is clear, and grade it. Grade 1 means no jagged edges and clear edges, grade 2 means slightly jagged edges, grade 3 means average jagged edges, grade 4 means more jagged edges, and grade 5 means obvious jagged edges. The results are shown in Table 3.

[0103] Table 3

[0104]

[0105] Conclusion: The tensile performance of Application Example 1 is only 57MPa, which is far lower than the standard of holographic anodized aluminum tensile performance requirement of ≥100MPa. The pattern integrity is poor, the slitting performance is poor, and it is unqualified;

[0106] The tensile performance of Application Example 2 is only 88MPa, which is lower than the standard of holographic electrochemical aluminum tensile performance requirement of ≥10MPa 0, and the slitting performance is poor and unqualified;

[0107] The key indicators of application example 3, such as tensile properties, biodegradability, adhesion, pattern integrity, and slitting properties, all meet the requirements and are qualified;

[0108] The pattern integrity of Application Example 4 is poor and unqualified;

[0109] The slitting property of Application Example 5 was poor and unqualified;

[0110] The key indicators of application example 6, such as tensile properties, biodegradability, adhesion, pattern integrity, and slitting properties, all meet the requirements and are qualified;

[0111] The adhesion of Application Example 7 was poor and unqualified;

[0112] The biodegradation rate of Application Example 8 is low and unqualified.

Claims

1. A biodegradable composite material, characterized in that: The raw materials for preparation include 60-78% of polylactic acid, 20-30% of toughening agent, 1-10% of transparent inorganic matter and 0.1-0.5% of cellulose in percentage by weight.

2. The biodegradable composite material according to claim 1, characterized in that: The melt index of the polylactic acid at 190° C. and 2.16 kg is 1-6 g / 10 min.

3. The biodegradable composite material according to claim 1, characterized in that: The toughening agent is a block polyether amide resin.

4. The biodegradable composite material according to claim 1, characterized in that: The cellulose is ethyl cellulose, and the mass fraction of ethoxy groups in the ethyl cellulose is 44-47.9%.

5. The biodegradable composite material according to claim 4, characterized in that: The viscosity of the ethyl cellulose at 25° C. is 3-5.5 mPa·s.

6. The biodegradable composite material according to claim 1, characterized in that: The transparent inorganic substance is selected from at least one of sodium oxide, silicon carbide, titanium oxide, zinc oxide, zinc sulfide, boron nitride and aluminum oxide.

7. A method for preparing the biodegradable composite material according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1 Drying: Place polylactic acid, toughening agent, transparent inorganic substance and cellulose in a vacuum drying oven and dry at 70-90°C for 10-15h to remove moisture and small molecule residues; S2 melt extrusion: add the dried polylactic acid, toughening agent, transparent inorganic substance and cellulose into a twin-screw extruder according to weight ratio for melt blending, the temperature distribution from the feed section to the die is 140-165°C, extrusion water-cooled pelletizing and drying to obtain pellets; S3 film blowing: adding the pellets into the film blowing machine for film blowing processing to obtain a biodegradable composite material.

8. An electrochemical aluminum film, characterized in that: The biodegradable composite material comprises the biodegradable composite material prepared according to claim 7.

9. The electrochemical aluminum film according to claim 8, characterized in that: The structure of the electrochemical aluminum film includes, from bottom to top, a biodegradable composite material layer, an electrochemical aluminum color layer, a holographic laser layer, an electroplating layer, and an electrochemical aluminum glue layer; the biodegradable composite material layer, the electrochemical aluminum color layer, the holographic laser layer, the electroplating layer, and the electrochemical aluminum glue layer, and each layer is fixedly connected.

10. A method for preparing an electrochemical aluminum film according to claim 9, characterized in that: The following steps are involved: S1 pre-prepare electrochemical aluminum color layer coating and electrochemical aluminum glue layer coating; S2: coating an electrochemical aluminum color layer coating on the biodegradable composite material, heating and drying in an oven channel to solidify the coating, thereby obtaining an electrochemical aluminum color layer; S3 holographically molds a pattern with laser holographic effect on the electroplated aluminum color layer to obtain a holographic laser layer; S4 performs vacuum electroplating on the holographic laser layer to obtain an electroplated layer; S5 applies an electrochemical aluminum adhesive layer coating on the electroplating layer, and heats, dries and solidifies it in an oven channel to obtain an electrochemical aluminum film.

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