Bio-based polyurethane pressure-sensitive adhesive as well as preparation method and application thereof

Abstract

The invention discloses a bio-based polyurethane pressure-sensitive adhesive and a preparation method thereof, and belongs to the technical field of adhesives, the preparation method comprises the following specific steps: (1) dehydrating bio-based polyol and an antioxidant, and dissolving to obtain a first mixed solution; and (2) adding diisocyanate and a catalyst into the first mixed solution for reaction, and adding an organic solvent to obtain the bio-based polyurethane pressure-sensitive adhesive. The product provided by the invention is a bio-based polyurethane pressure-sensitive adhesive, and has excellent pressure sensitivity and good weather resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesives, and particularly relates to a bio-based polyurethane pressure-sensitive adhesive and its preparation method and application. Background Art

[0002] Pressure-sensitive adhesives (PSA), also known as pressure-sensitive adhesives, are one of the most widely used adhesives in daily applications. They are coated on paper (such as kraft paper tape), stretched polypropylene (such as BOPP tape), polyethylene and other plastics (such as PVC tape), fabrics (such as non-woven fabric), metal foils, etc. to make pressure-sensitive adhesive tapes, commonly known as self-adhesive tapes or transparent tapes, which are used for bundling and fixing, packaging sealing, anti-corrosion and rust prevention, partial masking, spray painting protection, splicing materials, office supplies, artwork modification, temporary patching, surface protection, etc. They can also be used for labeling on glass, plastic, paper, wood and other commodities, as well as for label bonding on relatively flat and smooth ceramics, stainless steel and iron. In essence, they are a special type of viscoelastic polymer, usually obtaining a reliable bonding force on the substrate surface with only a small pressure applied at room temperature, producing a good bonding effect, and being not easily contaminated with the adhered object after peeling.

[0003] Commercial pressure-sensitive adhesives mainly consist of a polymer matrix, tackifying resin, fillers, plasticizers, anti-aging agents and some other chemical additives. At present, the polymer matrix for preparing pressure-sensitive adhesives is mainly petroleum-based synthetic polymer materials, commonly including acrylate copolymers, styrene block copolymers, ethylene-vinyl acetate copolymers, polyisoprene, polybutadiene synthetic rubbers and polyurethanes and other elastomers. However, as a disposable product used daily, the demand for pressure-sensitive adhesives is relatively large, which leads to an increasingly prominent contradiction between the effective supply of petrochemical resources, the main raw materials for preparing pressure-sensitive adhesives, and the growing product demand. At the same time, the environmental problems caused by non-degradable waste adhesive products are becoming increasingly severe. Therefore, it is particularly necessary to find biomass raw materials that can replace petroleum resources and have excellent performance, and develop environmentally friendly and renewable functional pressure-sensitive adhesive materials.

[0004] Therefore, it is an urgent problem for those skilled in the art to provide a bio-based polyurethane pressure-sensitive adhesive with excellent performance, environmental friendliness and renewability and its preparation method. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a bio-based polyurethane pressure-sensitive adhesive and its preparation method and application.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A preparation method of a bio-based polyurethane pressure-sensitive adhesive, comprising the following specific steps:

[0008] (1) Dehydrate and dissolve the bio - based polyol and antioxidant to obtain a first mixed solution;

[0009] (2) Add the diisocyanate and catalyst to the first mixed solution for reaction, and then add an organic solvent to obtain a bio - based polyurethane pressure - sensitive adhesive.

[0010] The polyurethane of the present invention is a polymer formed by the reaction of isocyanate with a compound containing active hydrogen. For example, polyol and isocyanate should form a urethane group. Due to the presence of strongly polar and reactive isocyanate groups (-NCO-) and urethane groups (-NHCOO-) in the polyurethane structure, it can form hydrogen bonds or chemical bonds with substrates containing active hydrogen, such as porous materials like foam, plastic, wood, leather, ceramic, etc., to generate adhesion force. When adhering to materials with a smooth surface (such as metal, glass, rubber, plastic, etc.), it also has excellent chemical adhesion force.

[0011] Preferably, in step (1), the mass ratio of the bio - based polyol to the antioxidant is 200 - 500:0.15 - 0.2. By adding the antioxidant in the above - mentioned proportion, the stability of the molecular chain segments during the reaction can be ensured.

[0012] Preferably, in step (1), the dissolution is carried out using an organic solvent, and the mass ratio of the bio - based polyol to the organic solvent is 1:0.5 - 1. The organic solvent mainly acts as a diluent and reaction medium. The solvent is added in two portions, which can increase the reaction concentration and reduce the reaction time required.

[0013] Preferably, in step (2), the mass ratio of the diisocyanate, the catalyst, the organic solvent, and the bio - based polyol is 50 - 100:0.01 - 0.02:100 - 250:200 - 500.

[0014] Preferably, the reaction conditions in step (2) are: reacting at 80 - 90 °C for 8 h. At this temperature, the diisocyanate can react quickly with the polyol and will not undergo side reactions due to too high a temperature.

[0015] Preferably, the organic solvent is ethyl acetate or butyl acetate. The reflux temperature of the organic solvent is moderate, which will not cause the reaction temperature to fail to reach the predetermined conditions due to too low a reflux temperature, and can ensure that the solvent in the gluing process can quickly volatilize into a film.

[0016] Preferably, the bio - based polyol is any one or two of soybean - oil - based polyol, rapeseed - oil - based polyol, and catalpa - oil - based polyol;

[0017] The diisocyanate is at least one of isophorone diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate;

[0018] The organic solvent is ethyl acetate or butyl acetate;

[0019] The antioxidant is antioxidant 1010;

[0020] The catalyst is any one of dibutyltin dilaurate, stannous octoate, cobalt octoate and zinc isooctanoate.

[0021] Preferably, the bio-based polyol has a molecular weight of 1000 - 2000, a functionality of 2 - 3, and a hydroxyl value in the range of 55 - 170 KOHmg / g.

[0022] The bio-based polyurethane pressure-sensitive adhesive obtained by the preparation method as described above.

[0023] The application of the bio-based polyurethane pressure-sensitive adhesive as described above in a pressure-sensitive adhesive tape.

[0024] From the above technical solutions, compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a bio-based polyurethane pressure-sensitive adhesive and a preparation method thereof. The product of the present invention is a bio-based polyurethane pressure-sensitive adhesive, which has excellent pressure sensitivity and good weather resistance. Specific Embodiments

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] Example 1

[0027] The present invention provides a preparation method of a bio-based polyurethane pressure-sensitive adhesive, and the specific steps are as follows:

[0028] (1) 468 g of soybean oil-based diol (with a molecular weight of about 1000) and 297 g of camphor oil-based diol (with a molecular weight of about 1000) are mixed evenly with 0.5 g of antioxidant 1010, vacuum dehydrated, and 450 g of ethyl acetate is added for dissolution to obtain a first mixed solution;

[0029] (2) Subsequently, 174 g of toluene diisocyanate and 0.03 g of dibutyltin dilaurate are added to the first mixed solution, and after reacting at (85 ± 5) °C for 8 h, 350 g of butyl acetate is added for dissolution to prepare a bio-based polyurethane pressure-sensitive adhesive;

[0030] The obtained bio-based polyurethane pressure-sensitive adhesive is coated on a 0.025 mm thick polyester film and cured at room temperature for 48 h. The resulting adhesive has excellent pressure sensitivity.

[0031] Example 2

[0032] The present invention provides a preparation method of a bio-based polyurethane pressure-sensitive adhesive, and the specific steps are as follows:

[0033] (1) 260 g of a soybean oil-based diol (with a molecular weight of about 1000) and 280 g of a soybean oil-based triol (with a molecular weight of 2000) are mixed and then mixed evenly with 0.5 g of antioxidant 1010. After vacuum dehydration, 230 g of butyl acetate is added for dissolution to obtain a first mixed solution;

[0034] (2) 57.8 g of isophorone diisocyanate and 0.02 g of stannous octoate are added to the first mixed solution and mixed evenly. After reacting at (85±5)°C for 8 h, 280 g of butyl acetate is added for dissolution to prepare a bio-based polyurethane pressure-sensitive adhesive;

[0035] The obtained bio-based polyurethane pressure-sensitive adhesive is coated on a polyester film with a thickness of 0.025 mm and cured at room temperature for 48 h. The resulting adhesive has excellent pressure sensitivity.

[0036] Example 3

[0037] The present invention provides a preparation method of a bio-based polyurethane pressure-sensitive adhesive, and the specific steps are as follows:

[0038] (1) 150 g of a rapeseed oil-based diol (with a molecular weight of about 1000), 375 g of a soybean oil-based triol (with a molecular weight of about 1500) and 0.5 g of antioxidant are mixed evenly. After vacuum dehydration, 270 g of ethyl acetate is added for dissolution to obtain a first mixed solution;

[0039] (2) 79.4 g of hexamethylene diisocyanate and 0.015 g of stannous octoate are mixed evenly and reacted at (85±5)°C for 8 h. Then, 200 g of ethyl acetate is added for dissolution to obtain a bio-based polyurethane pressure-sensitive adhesive;

[0040] The obtained bio-based polyurethane pressure-sensitive adhesive is coated on a polyester film with a thickness of 0.025 mm and cured at room temperature for 48 h. The resulting adhesive has excellent pressure sensitivity.

[0041] Comparative Example 1: Compared with Example 1, in this comparative example, both bio-based substances are replaced with polypropylene glycol with a molecular weight of 1000, and the remaining steps are the same.

[0042] Comparative Example 2: Compared with Example 2, in this comparative example, polypropylene glycol and polypropylene triol with the same molecular weight and the same functionality are used for substitution, and the remaining steps are the same.

[0043] Adhesion test: Tested in accordance with the standard of GB / T4852-2002. During the test, a pressure-sensitive tape sample with a length of 100 mm and a width of 50 mm was fixed on the inclined plane of the instrument. Then, copper balls with different numbers were released from the standard line with an inclination angle of 30° strictly according to the steps of the test standard, and the balls were allowed to roll down through the rolling section. Select the largest steel ball number staying on the test tape, and use the number of the steel ball to measure the initial adhesion performance of the pressure-sensitive adhesives prepared in Examples 1-3 and Comparative Examples 1-2;

[0044] Holding force test: In accordance with the standard of GB / T4851-2014, the pressure-sensitive adhesives prepared in Examples 1-3 and Comparative Examples 1-2 were made into standard pressure-sensitive tapes with a length of about 75 mm and a width of 25 mm. During the test, the standard tape was parallelly pasted between the test sample plate and the loading plate, aligned with the standard line on the test sample plate, and the excess tape part was cut off with a small force. Then, a standard pressure roller with a weight of 2 kg was rolled back and forth 3 times, placed at room temperature for 2 h, and then the test sample plate was vertically fixed on the sample rack, and a standard weight of 1 kg was suspended at the lower end, and the time when the sample fell off was recorded;

[0045] 180° peel strength test of pressure-sensitive adhesive: Tested in accordance with the standard of GB / T2792-2014, determined by an electronic tensile testing machine. The pressure-sensitive adhesives prepared in Examples 1-3 and Comparative Examples 1-2 were evenly coated on a PET film with a width of 25 mm and a length of 150 m using a 50-μm coater to make strip samples; the prepared samples were placed in an oven at 105 °C for drying for 10 min. After the pressure-sensitive tape was taken out, it was placed on a smooth glass surface, cooled to room temperature and pasted on the tinplate, and rolled back and forth with a roller 3 times, and then gently pressed evenly with the finger pulp; the test speed of the electronic tensile machine was 300 m / min for 180° peel strength;

[0046] The relevant test results are shown in Table 1 below. It can be seen that the products of the present invention have good bonding effects.

[0047] Table 1 Relevant test results of Examples 1-3 and Comparative Examples 1-2

[0048] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Initial tack force # 19 20 20 13 15 Holding tack force h 80 85 83 44 56 Peel strength N / 25mm 7.75 9.12 8.71 5.87 6.42

[0049] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preparation method of a bio-based polyurethane pressure-sensitive adhesive, characterized in that, It includes the following specific steps: (1) Dehydrate and dissolve the bio-based polyol and the antioxidant to obtain a first mixed solution; (2) Add the diisocyanate and the catalyst to the first mixed solution for reaction, and then add an organic solvent to obtain a bio-based polyurethane pressure-sensitive adhesive.

2. The preparation method of a bio-based polyurethane pressure-sensitive adhesive according to claim 1, characterized in that, In step (1), the mass ratio of the bio-based polyol to the antioxidant is 200 - 500:0.15 - 0.

2.

3. The preparation method of a bio-based polyurethane pressure-sensitive adhesive according to claim 1, characterized in that, In step (1), the dissolution is carried out using an organic solvent, and the mass ratio of the bio-based polyol to the organic solvent is 1:0.5 - 1.

4. The preparation method of a bio-based polyurethane pressure-sensitive adhesive according to claim 1, characterized in that, In step (2), the mass ratio of the diisocyanate, the catalyst, the organic solvent and the bio-based polyol is 50 - 100:0.01 - 0.02:100 - 250:200 - 500.

5. The preparation method of a bio-based polyurethane pressure-sensitive adhesive according to claim 1, characterized in that, The reaction conditions in step (2) are: reacting at 80 - 90 °C for 8 h.

6. The preparation method of a bio-based polyurethane pressure-sensitive adhesive according to claim 3, characterized in that, The organic solvent is ethyl acetate or butyl acetate.

7. The preparation method of a bio-based polyurethane pressure-sensitive adhesive according to claim 1, characterized in that, The bio-based polyol is any one or two of soybean oil-based polyol, rapeseed oil-based polyol, and catalpa oil-based polyol; The diisocyanate is at least one of isophorone diisocyanate, hexamethylene diisocyanate, and toluene diisocyanate; The organic solvent is ethyl acetate or butyl acetate; The antioxidant is antioxidant 1010; The catalyst is any one of dibutyltin dilaurate, stannous octoate, cobalt octoate, and zinc isooctanoate.

8. The preparation method of a bio-based polyurethane pressure-sensitive adhesive according to claim 7, characterized in that, The molecular weight of the bio-based polyol is 1000 - 2000, the functionality is 2 - 3, and the hydroxyl value selection range is 55 - 170 KOHmg / g.

9. A bio-based polyurethane pressure-sensitive adhesive obtained by the preparation method according to any one of claims 1-8.

10. The application of the bio-based polyurethane pressure-sensitive adhesive according to claim 9 in a pressure-sensitive adhesive tape.