Starch-based adhesive and preparation method thereof

Abstract

The invention discloses a starch-based adhesive and a preparation method thereof. The starch-based adhesive comprises the following raw materials in parts by mass: 50-60 parts of PLA, 20-30 parts of TPS, 8-12 parts of EVA, 1-4 parts of modified nano titanium dioxide, 0.5-2 parts of modified nano zirconium dioxide, 0.5-2 parts of polyol, 0.5-1 part of a surfactant and 0.01-0.1 part of an antioxidant. The invention also discloses a preparation method of the starch-based adhesive. According to the adhesive disclosed by the invention, PLA is used as a matrix, EVA, TPS, modified nano titanium dioxide and modified nano zirconium dioxide are used for modification, and under the combined action of polyol and a surfactant, the bonding strength is improved, the viscosity is reduced, and meanwhile, the adhesive also has good biodegradability; and when the adhesive is used for bonding corrugated boards, the adhesive has higher bonding strength, and the defect of corrugation exposure can be obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of adhesives, in particular to a starch-based adhesive and a preparation method thereof. Background Art

[0002] In the field of packaging production, adhesive is one of the indispensable auxiliary materials. Adhesive is needed to bond cardboard and cartons. Corrugated cardboard is made of at least one layer of corrugated core paper and surface paper bonded by adhesive, in which adhesive plays a bonding and reinforcing role.

[0003] Fluting is one of the common quality defects of corrugated cardboard. There are many factors that cause fluting of corrugated cardboard, and adhesive is one of the important reasons. The existing corrugated adhesive is mainly starch glue, which has a relatively low solid content and relatively weak bonding force. The coated and bonded corrugated cardboard is prone to fluting defects, especially for low-weight face paper, where fluting is more likely to occur and is more visually obvious. Summary of the invention

[0004] The object of the present invention is to provide a starch-based adhesive and a preparation method thereof, which can significantly improve the fluting defects of corrugated paperboard and also have good biodegradability. To achieve the above object, the present invention provides the following technical solutions:

[0005] A starch-based adhesive comprises the following raw materials by mass fraction: 50-60 parts of PLA, 20-30 parts of TPS, 8-12 parts of EVA, 1-4 parts of modified nano titanium dioxide, 0.5-2 parts of modified nano zirconium dioxide, 0.5-2 parts of polyol, 0.5-1 parts of surfactant and 0.01-0.1 parts of antioxidant.

[0006] Wherein, the modified nano titanium dioxide is coupled modified nano titanium dioxide.

[0007] Wherein, the modified nano zirconium dioxide is stearic acid modified nano zirconium dioxide.

[0008] Wherein, the surfactant includes one or more of silicon surfactant, fluorosilicone surfactant, sulfonate surfactant and alcohol ether surfactant.

[0009] The present invention also provides a method for preparing the above-mentioned starch-based adhesive, which comprises the following steps:

[0010] S1: dissolve titanate coupling agent or silane coupling agent in ethanol, add nano titanium dioxide, stir evenly, and then ultrasonically treat for 10-15 minutes. After filtration, dry to obtain modified nano titanium dioxide.

[0011] S2: Add stearic acid to ethanol, heat and dissolve, then add nano zirconium dioxide, stir evenly and perform ultrasonic treatment for 10-15 minutes, filter and dry to obtain modified nano zirconium dioxide.

[0012] S3: Add half amount of surfactant into ethanol aqueous solution and heat to 70-80°C, add TPS while magnetically stirring, and continue stirring for 0.5-1h to obtain TPS sol.

[0013] S4: Place PLA and EVA in chloroform solvent and stir at 50-55°C until completely dissolved, add modified nano titanium dioxide, modified nano zirconium dioxide, polyol, antioxidant and remaining surfactant and continue stirring for 0.5h, then add TPS sol while stirring and continue to keep stirring for 1-4h, then raise the temperature to 60-70°C and continue stirring until chloroform is completely evaporated, and cool naturally to obtain starch-based adhesive.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] The adhesive of the present invention has polylactic acid PLA, thermoplastic starch TPS and ethylene-vinyl acetate copolymer EVA as main components, does not contain water and can form a waterproof adhesive film with good waterproof performance. It will not increase the moisture of the facial paper or absorb the moisture of the facial paper during the coating, bonding and use process, and can significantly reduce the occurrence of corrugation defects.

[0016] The adhesive of the present invention contains modified nano titanium dioxide and modified nano zirconium dioxide, which can be evenly dispersed in the adhesive and penetrate into the tissue fiber under the action of surface modification and surfactant. The nano titanium dioxide and nano zirconium dioxide particles that penetrate into the surface layer and shallow surface layer of the tissue can improve the visual effect of the corrugation defect by utilizing their light absorption and light refraction characteristics.

[0017] The adhesive of the present invention uses PLA as a matrix, and is toughened and viscosity-reduced by EVA, TPS, modified nano titanium dioxide, and modified nano zirconium dioxide. Under the joint action of polyols and surfactants, the permeability, flexibility, and ductility of the adhesive can be improved, the bonding strength can be improved, the viscosity and melting temperature of the adhesive can be significantly reduced, and the processability can be improved.

[0018] The adhesive of the invention uses polylactic acid PLA and thermoplastic starch TPS, which are made of starch as raw materials, as main components. PLA and TPS are completely biodegradable, and the prepared adhesive has good biodegradability. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be clearly and completely described below in conjunction with embodiments.

[0020] Embodiment 1:

[0021] A starch-based adhesive, the raw materials of which include, by mass fraction, 55 parts of PLA, 25 parts of TPS, 10 parts of EVA, 3 parts of modified nano titanium dioxide, 1 part of modified nano zirconium dioxide, 1.5 parts of polyol, 0.8 parts of surfactant, and 0.05 parts of antioxidant. It comprises the following steps:

[0022] S1: Dissolve 0.5 parts of titanate coupling agent in 20 parts of ethanol, add nano titanium dioxide with an average particle size of 40-60 nm, stir evenly, and then perform ultrasonic treatment for 10 minutes. After filtration, dry to obtain modified nano titanium dioxide.

[0023] S2: Add 0.4 parts of stearic acid to 20 parts of ethanol, heat to dissolve, then add nano zirconium dioxide with an average particle size of 40-80 nm, stir evenly, and then perform ultrasonic treatment for 5-10 minutes. After suction filtration, dry to obtain modified nano zirconium dioxide.

[0024] S3: Add 0.3 parts of fluorosilicone surfactant and 0.1 parts of fatty acid ester sulfonate surfactant into 75% ethanol aqueous solution, heat to 75°C, add TPS while magnetic stirring, and continue stirring for 1 hour to prepare TPS sol.

[0025] S4: PLA and EVA are placed in chloroform solvent and stirred at 52°C until they are completely dissolved. Modified nano titanium dioxide, modified nano zirconium dioxide, polyol, antioxidant and the remaining 0.3 parts of fluorosilicone surfactant and 0.1 parts of fatty acid ester sulfonate surfactant are added, and stirring is continued for 0.5 hours. Then, TPS sol is added while stirring, and stirring is continued for 3 hours. The temperature is then raised to 65°C and stirring is continued until the chloroform is completely evaporated. After taking the material, it is naturally cooled to obtain a starch-based adhesive.

[0026] Embodiment 2:

[0027] A starch-based adhesive, the raw materials of which include, by mass fraction, 60 parts of PLA, 20 parts of TPS, 12 parts of EVA, 2 parts of modified nano titanium dioxide, 1 part of modified nano zirconium dioxide, 2 parts of polyol, 0.6 parts of surfactant, and 0.02 parts of antioxidant. It comprises the following steps:

[0028] S1: 0.4 parts of silane coupling agent was dissolved in 20 parts of ethanol, and nano titanium dioxide was added. The mixture was stirred evenly and then ultrasonically treated for 15 minutes. The modified nano titanium dioxide was obtained after filtration and drying.

[0029] S2: Add 0.2 stearic acid to 20 parts of ethanol, heat and dissolve, then add nano zirconium dioxide, stir evenly and perform ultrasonic treatment for 15 minutes, filter and dry to obtain modified nano zirconium dioxide.

[0030] S3: Add 0.3 parts of surfactant alkylphenol polyoxyethylene ether into 70% ethanol aqueous solution, heat to 80°C, add TPS while magnetically stirring, and continue stirring for 0.8h to obtain TPS sol.

[0031] S4: PLA and EVA are placed in chloroform solvent and stirred at 54°C until they are completely dissolved. Modified nano titanium dioxide, modified nano zirconium dioxide, polyols, antioxidants and the remaining surfactants are added and stirring is continued for 0.5h. Then, TPS sol is added while stirring and stirring is continued for 4h. The temperature is then raised to 65°C and stirring is continued until the chloroform is completely evaporated. The starch-based adhesive is obtained by natural cooling.

[0032] The starch-based adhesive of the present invention is melted and used for bonding corrugated paperboards, which can significantly improve the fluting defects on the basis of having a higher bonding strength.

[0033] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0034] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A starch-based adhesive, characterized in that: The raw materials include, by mass fraction: 50-60 parts of PLA, 20-30 parts of TPS, 8-12 parts of EVA, 1-4 parts of modified nano titanium dioxide, 0.5-2 parts of modified nano zirconium dioxide, 0.5-2 parts of polyol, 0.5-1 parts of surfactant, and 0.01-0.1 parts of antioxidant; It includes the following steps: S1: dissolving a titanate coupling agent or a silane coupling agent in ethanol, adding nano-titanium dioxide, stirring evenly, ultrasonically treating for 10-15 minutes, filtering, and drying to obtain modified nano-titanium dioxide; S2: adding stearic acid to ethanol, heating and dissolving, then adding nano zirconium dioxide, stirring evenly, ultrasonically treating for 10-15 minutes, filtering and drying to obtain modified nano zirconium dioxide; S3: Add half of the surfactant to the ethanol aqueous solution and heat to 70-80°C while adding TPS under magnetic stirring and continue stirring for 0.5-1h to obtain TPS sol; S4: Place PLA and EVA in chloroform solvent and stir at 50-55°C until completely dissolved, add modified nano titanium dioxide, modified nano zirconium dioxide, polyol, antioxidant and remaining surfactant and continue stirring for 0.5h, then add TPS sol while stirring and continue to keep stirring for 1-4h, then raise the temperature to 60-70°C and continue stirring until chloroform is completely evaporated, and cool naturally to obtain starch-based adhesive.

2. A starch-based adhesive according to claim 1, characterized in that: The modified nano titanium dioxide is coupled modified nano titanium dioxide, and the modified nano zirconium dioxide is stearic acid modified nano zirconium dioxide.

3. A starch-based adhesive according to claim 1, characterized in that: The surfactant includes one or more of a silicon surfactant, a fluorosilicone surfactant, a sulfonate surfactant, and an alcohol ether surfactant.

4. A starch-based adhesive according to claim 1, characterized in that: The raw materials include, by mass fraction, 55 parts of PLA, 25 parts of TPS, 10 parts of EVA, 3 parts of modified nano titanium dioxide, 1 part of modified nano zirconium dioxide, 1.5 parts of polyol, 0.8 parts of surfactant, and 0.05 parts of antioxidant.