Disclosure of Invention
The application provides a polylactic acid aluminized film and a preparation method thereof in order to improve the adhesive force of the polylactic acid film and an aluminum layer and improve the durability of the polylactic acid aluminized film.
In a first aspect, the present application provides a polylactic acid aluminizer, which adopts the following technical scheme:
The polylactic acid aluminizer comprises a polylactic acid film material, a polyurethane coating and an aluminized layer which are sequentially arranged, wherein the polyurethane coating is formed by solidifying a polyurethane coating, the polyurethane coating is subjected to plasma surface treatment, and the polyurethane coating is prepared from the following raw materials in parts by weight:
70-80 parts of hydroxy acrylic ester emulsion;
1-1.5 parts of isocyanate modified cellulose;
7-9 parts of isocyanate curing agent;
2-4 parts of an auxiliary agent;
20-30 parts of water.
By adopting the technical scheme, the polyurethane coating is arranged between the polylactic acid film material and the aluminized layer to serve as the bonding layer, so that the bonding force between the polylactic acid film material and the aluminized layer can be effectively improved. The isocyanate modified cellulose is doped into the polyurethane coating, and the interfacial compatibility of the modified cellulose with a polyurethane structure is improved after the modification of the isocyanate, so that the dispersibility of the cellulose in the polyurethane coating is improved, the crosslinking compactness of the inside of the polyurethane coating is improved, the interfacial interaction of the polyurethane coating is enhanced, the binding force between the polyurethane coating and an aluminized layer and between the polyurethane coating and a polylactic acid film material can be effectively improved, and the adhesive force of the aluminized layer on the surface of the polylactic acid film material is enhanced.
The isocyanate modified cellulose also increases the action site of the polyurethane coating subjected to plasma treatment, after the isocyanate modified cellulose is subjected to plasma surface treatment, the active groups on the surface are increased, the surface activity of the polyurethane coating is effectively improved, the fixing effect on aluminum is enhanced during aluminum plating, the binding force between the polyurethane coating and the polylactic acid film is further enhanced, and the adhesive force durability of the aluminum plating layer is improved.
Alternatively, the isocyanate modified cellulose is formed by reacting an isocyanate with cellulose, the isocyanate including an aromatic monoisocyanate and an aliphatic diisocyanate.
By adopting the technical scheme, the aromatic monoisocyanate has the characteristic of rigidity of benzene rings, the bonding force between a polyurethane system and a cellulose interface can be improved, the aliphatic diisocyanate can realize crosslinking between cellulose, a network fiber structure is formed at the polyurethane coating interface, and the adhesive force of an aluminized film on the surface of the polyurethane coating is improved.
Optionally, the isocyanate modified cellulose is prepared by reacting cellulose with isocyanate according to a mass ratio of 1 (0.48-0.65), wherein the isocyanate comprises 4-n-butylphenol isocyanate and hexamethylene diisocyanate according to a mass ratio of 1 (0.2-0.3).
By adopting the technical scheme, the proportion of isocyanate to the surface of cellulose is controlled so as to improve the crosslinking compactness of the polyurethane coating, the tail end of 4-n-butylphenol isocyanate is provided with n-butyl chains, and the N-butyl chains and polyurethane chain segments form good entanglement, so that the compactness of the polyurethane coating is improved, the barrier property is improved, the proportion of 4-n-butylphenol isocyanate and hexamethylene diisocyanate is controlled, the crosslinking between the cellulose is kept at a lower level, the excessive crosslinking is prevented from forming aggregation, the interface interaction is fully exerted, and the durability of the polylactic acid aluminized film is improved.
Optionally, the auxiliary agent comprises one or two of a leveling agent and a thickening agent.
Optionally, the hydroxy acrylic ester emulsion is prepared from the following raw materials in parts by weight:
45-55 parts of hydroxy acrylic ester monomer;
2-5 parts of short-chain aliphatic acrylate monomer;
2-5 parts of long-chain aliphatic acrylate monomer;
2-3 parts of an emulsifier;
0.2-0.6 parts of an initiator;
60-70 parts of water.
By adopting the technical scheme, under the cooperation of the short-chain aliphatic acrylate monomer and the long-chain aliphatic acrylate monomer, the interfacial interaction of the polyurethane coating is enhanced, the interfacial bonding capability with isocyanate modified cellulose is improved, and the bonding durability of the polyurethane coating is further improved.
Optionally, the short-chain aliphatic acrylate monomer comprises one or more of methyl acrylate, ethyl acrylate, propyl acrylate, methyl methacrylate, ethyl methacrylate and propyl methacrylate, and the long-chain aliphatic acrylate monomer comprises one or more of dodecyl methacrylate, tetradecyl methacrylate and hexadecyl methacrylate.
Optionally, the hydroxy acrylic ester is one or more of hydroxy ethyl acrylate, hydroxy propyl acrylate, hydroxy ethyl methacrylate and hydroxy propyl methacrylate.
Optionally, the emulsifier comprises one or both of sodium dodecyl sulfate and sodium stearate.
Optionally, the initiator comprises one or both of potassium persulfate and ammonium persulfate.
Alternatively, the isocyanate curing agent is a water-dispersible polyisocyanate based on hexamethylene diisocyanate.
By adopting the technical scheme, the water-dispersible polyisocyanate based on hexamethylene diisocyanate is suitable for forming a stable cross-linking structure with the hydroxy acrylic ester emulsion, and the cross-linking structure is compact.
Optionally, the thickness of the polylactic acid film material is 15-20 μm.
Optionally, the thickness of the aluminized layer is 400-450 angstroms.
Optionally, the thickness of the polyurethane coating is 0.1-0.3 μm.
In a second aspect, the preparation method of the polylactic acid aluminizer provided by the application adopts the following technical scheme:
The preparation method of the polylactic acid aluminizer comprises the following steps:
Stirring and mixing the hydroxyl acrylic ester emulsion and isocyanate modified cellulose, heating to 40-45 ℃, then adding an isocyanate curing agent, an auxiliary agent and water, mixing, stopping heating after stirring uniformly, and continuing stirring for 20-60 min to obtain a polyurethane coating;
Coating polyurethane coating on one side of the polylactic acid film material, and drying and curing to form a polyurethane coating;
and carrying out plasma treatment on the surface of the polyurethane coating, then carrying out vacuum aluminum plating on the surface of the polyurethane coating to form an aluminum plating layer, and drying and curing to obtain the polylactic acid aluminum plating film.
By adopting the technical scheme, before aluminum is vacuum deposited on the surface of the polyurethane coating, plasma treatment is carried out, so that the surface activity of the polyurethane coating is improved, the interface of aluminum is compatible, and the adhesive force between the aluminum layer and the polyurethane coating is improved.
Optionally, the preparation method of the isocyanate modified cellulose comprises the following steps:
Dispersing cellulose in an organic solvent, heating, adding isocyanate, stirring and reacting until the-NCO content in a reaction system is less than 0.1%, stopping the reaction, filtering, washing and drying to obtain the isocyanate modified cellulose.
By adopting the technical scheme, the hydroxyl groups of the cellulose are combined with isocyanate in a reaction way, so that the surface structure of the cellulose is modified.
Optionally, the preparation method of the hydroxy acrylic ester emulsion comprises the following steps:
Dispersing part of the emulsifier in water uniformly, then adding hydroxyl acrylate monomer, short-chain aliphatic acrylate monomer and long-chain aliphatic acrylate monomer, mixing, heating, gradually adding initiator to react, adding the rest of the emulsifier, and obtaining the hydroxyl acrylate emulsion after the reaction is finished.
Optionally, the working gas in the plasma treatment method is air, the flow rate of the working gas is 2000-2500 sccm, and the power of the plasma treatment is 3-5 kW.
By adopting the technical scheme, the parameters of the plasma treatment are adjusted, the surface activity of the polyurethane coating is fully improved, and the influence on the stability of the polyurethane coating is reduced.
In summary, the application has the following beneficial effects:
1. According to the application, the polyurethane coating is arranged between the polylactic acid film material and the aluminum plating layer to serve as the bonding layer, so that the bonding force between the polylactic acid film material and the aluminum plating layer can be effectively improved. The isocyanate modified cellulose is doped into the polyurethane coating, and the interfacial compatibility of the modified cellulose with a polyurethane structure is improved after the modification of the isocyanate, so that the dispersibility of the cellulose in the polyurethane coating is improved, the crosslinking compactness of the inside of the polyurethane coating is improved, the interfacial interaction of the polyurethane coating is enhanced, the binding force between the polyurethane coating and an aluminized layer and between the polyurethane coating and a polylactic acid film material can be effectively improved, and the adhesive force of the aluminized layer on the surface of the polylactic acid film material is enhanced.
2. After the isocyanate modified cellulose is subjected to plasma surface treatment, active groups on the surface are increased, the surface activity of a polyurethane coating is effectively improved, in addition, the aromatic monoisocyanate has the characteristic of benzene ring rigidity, the bonding force between a polyurethane system and a cellulose interface can be improved, the aliphatic diisocyanate can realize crosslinking among the cellulose, a network fiber structure is formed at the polyurethane coating interface, the adhesive force of an aluminizer on the surface of the polyurethane coating is improved, the fixing effect on aluminum is enhanced during aluminizing, the bonding force between the polyurethane coating and a polylactic acid film is further enhanced, and the adhesive force durability of the aluminized layer is improved.
Detailed Description
The present application will be described in further detail with reference to fig. 1.
Preparation example 1
The preparation method of the isocyanate modified cellulose comprises the following steps:
1kg of cellulose, 0.48kg of isocyanate and 5L of organic solvent were weighed.
The cellulose is microcrystalline cellulose, the polymerization degree is 200, the particle size is 20-30 nm, the isocyanate is composed of 0.4kg of 4-n-butylphenol isocyanate and 0.08kg of hexamethylene diisocyanate, and the organic solvent is toluene.
Dispersing cellulose in an organic solvent, heating to 55 ℃, adding isocyanate, stirring and reacting until the-NCO content in a reaction system is less than 0.1%, stopping the reaction, filtering, washing and drying to obtain the isocyanate modified cellulose.
Preparation example 2
The preparation method of the isocyanate modified cellulose is different from that of the preparation example 1 in the proportion of raw materials.
Cellulose 1kg, isocyanate 0.65kg and organic solvent 5L.
The cellulose is microcrystalline cellulose, the polymerization degree is 200, the particle size is 20-30 nm, the isocyanate is composed of 0.5kg of 4-n-butylphenol isocyanate and 0.15kg of hexamethylene diisocyanate, and the organic solvent is toluene.
Preparation example 3
The preparation of isocyanate-modified cellulose differs from preparation 1 in the specific choice of isocyanate.
The isocyanate specifically consisted of 0.27kg of phenyl isocyanate and 0.08kg of hexamethylene diisocyanate.
Preparation example 4
The preparation of isocyanate-modified cellulose differs from preparation 1 in the specific choice of isocyanate.
The isocyanate was specifically 4-n-butylphenol isocyanate 0.48kg.
Preparation example 5
The preparation of isocyanate-modified cellulose differs from preparation 1 in the specific choice of isocyanate.
The isocyanate consisted of 0.4kg of 4-n-butylphenol isocyanate and 0.12kg of 4', 4-diphenylmethane diisocyanate.
Preparative example 1
The preparation method of the hydroxy acrylic ester emulsion comprises the following steps:
4.5kg of hydroxy acrylic ester monomer, 0.2kg of short-chain aliphatic acrylic ester monomer, 0.2kg of long-chain aliphatic acrylic ester monomer, 0.2kg of emulsifier, 0.02kg of initiator and 6L of water are weighed.
The preparation method comprises the steps of preparing a hydroxyl acrylic ester monomer, namely hydroxyethyl methacrylate, a short-chain aliphatic acrylic ester monomer, namely methyl acrylate, a long-chain aliphatic acrylic ester monomer, namely dodecyl methacrylate, an emulsifying agent, namely sodium dodecyl sulfate, an initiator, namely ammonium persulfate, and dissolving the initiator in 0.5L of water in advance to obtain an initiator solution for standby.
Uniformly dispersing 50wt% of the total mass of the emulsifier in 5.5L of water, adding a hydroxy acrylic ester monomer, a short-chain aliphatic acrylic ester monomer and a long-chain aliphatic acrylic ester monomer, mixing, heating to 80 ℃, gradually dropwise adding an initiator solution for reaction, dropwise adding the initiator within 1.5h, adding the rest of the emulsifier after dropwise adding the initiator for 1h, continuing to react for 3.5h after dropwise adding the initiator, and cooling after the reaction is finished to obtain the hydroxy acrylic ester emulsion.
PREPARATION EXAMPLE 2
The preparation method of the hydroxy acrylic ester emulsion is different from that of the preparation example 1 in the proportion of raw materials.
5.5Kg of hydroxy acrylate monomer, 0.5kg of short-chain aliphatic acrylate monomer, 0.5kg of long-chain aliphatic acrylate monomer, 0.3kg of emulsifier, 0.06kg of initiator and 7L of water.
The hydroxyl acrylic ester monomer is hydroxyethyl methacrylate, the short-chain aliphatic acrylic ester monomer is methyl acrylate, the long-chain aliphatic acrylic ester monomer is dodecyl methacrylate, the emulsifier is sodium dodecyl sulfate, and the initiator is ammonium persulfate.
Preparative example 3
The preparation method of the hydroxy acrylic ester emulsion is different from that of the preparation example 1 in the proportion of raw materials.
4.5Kg of hydroxy acrylate monomer, 0.4kg of short-chain aliphatic acrylate monomer, 0.2kg of emulsifier, 0.02kg of initiator and 6L of water.
The hydroxyl acrylic ester monomer is hydroxyethyl methacrylate, the short-chain aliphatic acrylic ester monomer is methyl acrylate, the emulsifier is sodium dodecyl sulfate, and the initiator is ammonium persulfate.
Example 1
A polylactic acid aluminizer is shown in fig. 1, and comprises a polylactic acid film material 1, a polyurethane coating 2 and an aluminized layer 3 which are sequentially arranged.
The preparation method of the polylactic acid aluminizer comprises the following steps:
7kg of hydroxy acrylic ester emulsion, 0.1kg of isocyanate modified cellulose, 0.7kg of isocyanate curing agent, 0.2kg of auxiliary agent and 2L of water are weighed.
The hydroxyl acrylic ester emulsion is derived from preparation example 1, the isocyanate modified cellulose is derived from preparation example 1, the isocyanate curing agent can be water dispersible polyisocyanate based on hexamethylene diisocyanate, specifically Desmodur DA, the auxiliary agent consists of 0.1kg of a leveling agent and 0.1kg of a thickening agent, the leveling agent is specifically BYK-333, and the thickening agent is BYK-428.
And (3) stirring and mixing the hydroxyl acrylic emulsion and the isocyanate modified cellulose, heating to 40 ℃, adding an isocyanate curing agent, an auxiliary agent and water, mixing, stopping heating after stirring uniformly, and continuing stirring for 60 minutes to obtain the polyurethane coating.
And (3) coating polyurethane coating on one side of the polylactic acid film, wherein the thickness of the polylactic acid film is 20 mu m, the coating weight is 1g/m2, then, conveying the base material into a drying tunnel, drying and curing, and dividing the drying tunnel into seven sections, wherein the temperature of each section is 60 ℃, 80 ℃, 110 ℃, 120 ℃, 110 ℃, 105 ℃ and 100 ℃ in sequence, so as to form the polyurethane coating with the thickness of 0.1 mu m.
And (3) carrying out glow discharge type plasma treatment on the surface of the polyurethane coating, wherein the working gas in the plasma treatment method is air, the flow rate of the working gas is 2000sccm, and the power of the plasma treatment is 5kW.
Finally, feeding the aluminum alloy into a vacuum evaporation device, carrying out vacuum evaporation on aluminum oxide on the surface of the polyurethane coating, wherein in the vacuum evaporation process, the aluminum plating speed is 490m/s, the temperature for heating the aluminum wire is 1400 ℃, the wire feeding speed of the aluminum wire is 700mm/min, forming an aluminum plating layer with the thickness of 400 angstroms, and then drying and curing the aluminum alloy in a 60 ℃ oven for 72 hours to obtain the polylactic acid aluminum plating film.
Example 2
A polylactic acid aluminizer is shown in fig. 1, and comprises a polylactic acid film material 1, a polyurethane coating 2 and an aluminized layer 3 which are sequentially arranged.
The preparation method of the polylactic acid aluminizer comprises the following steps:
8kg of hydroxy acrylic ester emulsion, 0.15kg of isocyanate modified cellulose, 0.9kg of isocyanate curing agent, 0.4kg of auxiliary agent and 3L of water are weighed.
Wherein the hydroxyl acrylic ester emulsion is derived from preparation example 2, the isocyanate modified cellulose is derived from preparation example 2, the isocyanate curing agent can be water dispersible polyisocyanate based on hexamethylene diisocyanate, specifically Desmodur DA, the auxiliary agent consists of 0.2kg of flatting agent and 0.2kg of thickening agent, the flatting agent is specifically BYK-333, and the thickening agent is BYK-428.
And (3) stirring and mixing the hydroxyl acrylic emulsion and the isocyanate modified cellulose, heating to 45 ℃, adding an isocyanate curing agent, an auxiliary agent and water, mixing, stopping heating after stirring uniformly, and continuing stirring for 20min to obtain the polyurethane coating.
And (3) coating polyurethane coating on one side of the polylactic acid film, wherein the thickness of the polylactic acid film is 20 mu m, the coating weight is 1g/m2, then, conveying the base material into a drying tunnel, drying and curing, and dividing the drying tunnel into seven sections, wherein the temperature of each section is 60 ℃, 80 ℃, 110 ℃, 120 ℃, 110 ℃, 105 ℃ and 100 ℃ in sequence, so as to form the polyurethane coating with the thickness of 0.1 mu m.
And (3) carrying out glow discharge type plasma treatment on the surface of the polyurethane coating, wherein the working gas in the plasma treatment method is air, the flow rate of the working gas is 2500sccm, and the power of the plasma treatment is 3kW.
Finally, feeding the aluminum alloy into a vacuum evaporation device, carrying out vacuum evaporation on aluminum oxide on the surface of the polyurethane coating, wherein in the vacuum evaporation process, the aluminum plating speed is 490m/s, the temperature for heating the aluminum wire is 1400 ℃, the wire feeding speed of the aluminum wire is 700mm/min, forming an aluminum plating layer with the thickness of 400 angstroms, and then drying and curing the aluminum alloy in a 60 ℃ oven for 72 hours to obtain the polylactic acid aluminum plating film.
Example 3
The difference between the preparation method of the polylactic acid aluminized film and the embodiment 1 is that the raw material proportion of the polyurethane coating is different.
0.75Kg of hydroxy acrylic ester emulsion, 0.12kg of isocyanate modified cellulose, 0.82kg of isocyanate curing agent, 0.3kg of auxiliary agent and 2.6L of water.
The hydroxyl acrylic ester emulsion is derived from preparation example 1, the isocyanate modified cellulose is derived from preparation example 1, the isocyanate curing agent can be water dispersible polyisocyanate based on hexamethylene diisocyanate, specifically Desmodur DA, the auxiliary agent consists of 0.15kg of a leveling agent and 0.15kg of a thickening agent, the leveling agent is specifically BYK-333, and the thickening agent is BYK-428.
Example 4
The difference between the preparation method of polylactic acid aluminized film and the embodiment 3 is that the source of isocyanate modified cellulose is different.
The isocyanate modified cellulose was derived from preparation example 3.
Example 5
The difference between the preparation method of polylactic acid aluminized film and the embodiment 3 is that the source of isocyanate modified cellulose is different.
The isocyanate modified cellulose was derived from preparation example 4.
Example 6
The difference between the preparation method of polylactic acid aluminized film and the embodiment 3 is that the source of isocyanate modified cellulose is different.
The isocyanate modified cellulose was derived from preparation example 5.
Example 7
The difference between the preparation method of the polylactic acid aluminized film and the embodiment 3 is that the source of the hydroxy acrylic ester emulsion is different.
The hydroxyacrylate emulsion was derived from preparation 3.
Comparative example 1
A method for producing an aluminum laminated film of polylactic acid, which is different from example 3 in the raw materials of the polyurethane coating.
0.75Kg of hydroxy acrylic ester emulsion, 0.82kg of isocyanate curing agent, 0.3kg of auxiliary agent and 2.6L of water are weighed.
The hydroxyl acrylic ester emulsion is derived from preparation example 1, the isocyanate curing agent can be water-dispersible polyisocyanate based on hexamethylene diisocyanate, specifically Desmodur DA, the auxiliary agent consists of a leveling agent kg and a thickening agent kg, the leveling agent is specifically BYK-333, and the thickening agent is BYK-428.
Comparative example 2
A method for producing an aluminum laminated film of polylactic acid, which is different from example 3 in the raw materials of the polyurethane coating.
0.75Kg of hydroxy acrylic ester emulsion, 0.12kg of cellulose, 0.82kg of isocyanate curing agent, 0.3kg of auxiliary agent and 2.6L of water are weighed.
The hydroxyl acrylic ester emulsion is derived from preparation example 1, the cellulose is specifically microcrystalline cellulose, the polymerization degree is 200, the isocyanate curing agent can be water-dispersible polyisocyanate based on hexamethylene diisocyanate, specifically Desmodur DA, the auxiliary agent consists of a leveling agent kg and a thickening agent kg, the leveling agent is specifically BYK-333, and the thickening agent is BYK-428.
Comparative example 3
The comparative example differs from example 3 in that the polylactic acid film was subjected to a glow discharge type plasma treatment prior to the coating of the polyurethane coating, the working gas in the plasma treatment method was air, the flow rate of the working gas was 2000sccm, and the power of the plasma treatment was 5kW.
In addition, before the aluminum layer is deposited on the surface of the polyurethane coating, plasma treatment is not performed.
Performance testing
Adhesive force of aluminized layer referring to QB/T2358-1998 "method for testing heat seal Strength of Plastic film packaging bag", heat seal layer of EAA film and aluminized layer of polylactic acid aluminized film are heat sealed, heat seal temperature is 115 deg.C, pressure is 0.4MPa, heat seal time is 2s, and then aluminium plated layer is peeled off from polylactic acid film by means of tensile tester, so as to obtain adhesive force data, and the result is shown in Table 1.
Adhesion durability. The aluminum-plated polylactic acid film was further aged in an oven at 120 ℃ with 70% humidity for 240 hours, and then subjected to an adhesion test for the aluminum-plated layer, the results of which are shown in table 1.
Barrier Properties referring to ASTM D-3985 and ASTM F-1249, the oxygen permeability and water vapor permeability of the polylactic acid aluminized film were measured, and the results are shown in Table 2.
TABLE 1
| Adhesive force (N/15 mm) | Adhesion after aging (N/15 mm) |
| Example 1 | 3.2 | 2.7 |
| Example 2 | 3.0 | 2.5 |
| Example 3 | 3.2 | 2.9 |
| Example 4 | 3.0 | 2.3 |
| Example 5 | 2.9 | 2.2 |
| Example 6 | 2.9 | 2.3 |
| Example 7 | 3.0 | 2.4 |
| Comparative example 1 | 2.4 | 1.4 |
| Comparative example 2 | 2.5 | 1.5 |
| Comparative example 3 | 2.7 | 1.9 |
TABLE 2
As can be seen from the combination of table 1 and table 2, the aluminum laminated film of the polylactic acid prepared in examples 1 to 3 is better in terms of adhesion of the aluminum layer and durability of the adhesion of the aluminum layer, while good oxygen barrier property and water vapor barrier property are ensured, and compared with comparative examples 1 to 3, it can be seen that after the isocyanate modified cellulose is doped in the polyurethane coating, the adhesion force between the polyurethane coating and the aluminum laminated film and between the polyurethane coating and the polylactic acid film material is enhanced, so that the adhesion force of the aluminum layer of the polylactic acid aluminum laminated film is improved, and in addition, the adhesion force between the polyurethane coating and the aluminum laminated film is further improved by performing plasma treatment on the polyurethane coating, so that the durability of the adhesion force of the aluminum layer is improved.
It can be seen from the combination of examples 3 and examples 4 to 6 and comparative example 2 that the cellulose has a remarkable reinforcing effect on the interfacial bonding ability of the polyurethane coating after the modification of the isocyanate, and the adhesion durability of the aluminum layer can be further improved by properly selecting the aromatic monoisocyanate and the aliphatic diisocyanate.
It can be seen from the combination of examples 3 and 7 that polymerization of long-chain aliphatic acrylate monomers in the hydroxyacrylate emulsion can further improve the adhesion durability of the aluminum layer.
The present embodiment is merely illustrative of the present application and not limiting, and one skilled in the art, after having read the present specification, may make modifications to the embodiment without creative contribution as required, but is protected by patent law within the scope of the claims of the present application.