A polyurethane-based double-layer wiper strip and its preparation method and application

Abstract

The present invention relates to the technical field of materials for floor scrubber wiper strips, and more particularly to a polyurethane-based double-layer wiper strip, its preparation method, and its application. The polyurethane-based double-layer wiper strip comprises: a first polyurethane layer and a second polyurethane layer; the first polyurethane layer is 2 to 4 times thicker than the second polyurethane layer; the second polyurethane layer is 1 to 2 mm thick. The first polyurethane layer is prepared using the following raw materials by weight: 80 to 120 parts of the first polyurethane, 0.02 to 0.06 parts of a defoaming agent, and 1 to 3 parts of a filler. The polyurethane-based double-layer wiper strip of the present invention contains a large number of hydrogen bonds and dynamic covalent bonds, which synergistically enhance the polyurethane's repair and tear resistance. Furthermore, the polyurethane-based double-layer wiper strip of the present invention has a high molecular weight, improved flexibility, elasticity, and excellent antioxidant properties.

Description

Technical Field

[0001] The present invention relates to the technical field of materials for floor scrubber wiper strips, and in particular to a polyurethane-based double-layer wiper strip, a preparation method, and applications thereof. Background Art

[0002] As society continues to develop, people's living environments are constantly changing. Cleaning the floors of public places and areas is particularly important. Improper cleaning not only affects the appearance and creates a negative experience for people, but also can easily lead to bacterial growth, impacting health. In the past, most of these public areas were cleaned bit by bit by cleaners using long mops. This process was physically tiring, time-consuming, and inefficient. Later, a floor scrubber was developed that could replace manual cleaning, increasing cleaning efficiency while saving manpower and costs.

[0003] The primary component used for cleaning floors on a floor scrubber is the wiper strip. Made primarily of polyurethane, these strips are subject to prolonged contact and friction with the floor during operation, making them susceptible to wear and tear. This reduces wiper efficiency and service life. Consequently, numerous researchers have investigated and improved the wear and tear resistance of polyurethane.

[0004] For example, CN105237731B "A heat-resistant and wear-resistant polyurethane material" solves the wear-resistant, heat-resistant and mechanical properties of polyurethane by introducing fluorine-containing groups into the polyurethane structure and coordinating with nano-silica and silane coupling agents. However, the fluorine element has a huge impact on the environment and is prone to environmental pollution during the subsequent processing. In addition, the public document does not address the problem of polyurethane tear resistance.

[0005] For example, CN105924937A "An environmentally friendly tear-resistant and toughened modified silicone PU flame-retardant plastic material" prepares a plastic material containing a water-based coating layer, a tear-resistant and toughened modified layer, a shock-absorbing silicone PU elastic layer and a closed primer layer, which improves the tear resistance and toughness of the plastic surface layer, but this method does not mention or solve the wear resistance of the plastic material.

[0006] In addition, the applicant disclosed a polyurethane wiper strip with low hardness, high resilience, mildew and antibacterial properties, yellowing resistance, wear resistance and wiper working performance in the previous application document CN115340655B "A polyurethane wiper strip material and its application". With the company's continuous progress and innovation, the applicant found that polyurethane wiper strips are mostly used once, and once damaged, they need to be replaced, which increases the cost of use.

[0007] Therefore, it is urgent to develop a polyurethane wiper strip that is wear-resistant and tear-resistant, has good flexibility, and has self-repairing ability to save usage costs. Summary of the Invention

[0008] The main purpose of the present invention is to provide a polyurethane-based double-layer wiper strip, a preparation method and an application. The polyurethane-based double-layer wiper strip of the present invention has good flexibility, wear resistance, tear resistance and self-repair function, a longer service life and saves use costs.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] On one hand, the present invention provides a double-layer wiper strip based on a polyurethane substrate, comprising a first polyurethane layer and a second polyurethane layer; the thickness of the first polyurethane layer is 2 to 4 times the thickness of the second polyurethane layer; the thickness of the second polyurethane layer is 1 to 2 mm; the raw materials for preparing the first polyurethane layer include the following components in parts by mass: 80 to 120 parts of the first polyurethane, 0.02 to 0.06 parts of a defoaming agent, and 1 to 3 parts of a filler.

[0011] In some embodiments, the raw materials for preparing the second polyurethane layer include the following components in parts by mass: 80 to 120 parts of the second polyurethane, 0.02 to 0.06 parts of a defoaming agent, and 0.2 to 0.8 parts of a filler.

[0012] By regulating the composition of the present invention, the second polyurethane layer has excellent tear resistance and high self-repairing properties, but its high hardness affects the toughness of the polyurethane-based double-layer wiper strip, hindering its better adhesion to the ground and prone to noise during operation. By regulating the raw material ratio of the first polyurethane layer, the first polyurethane layer has good toughness and wear resistance, but its tear resistance is poor. By regulating the raw material ratio of the first and second polyurethane layers and coordinating the thickness of the first and second polyurethane layers, the applicant can achieve a polyurethane-based double-layer wiper strip with good tear resistance without affecting its flexibility.

[0013] The present application adds a defoaming agent to prevent air bubbles from being incorporated into the polyurethane wiper rubber strip during the polyurethane mixing and stirring process, thereby preventing the density from decreasing.

[0014] In some embodiments, the method for preparing the first polyurethane comprises the following steps: dissolving D-arabitol in a solvent, and then adding the D-arabitol dissolved in the solvent to the compound represented by formula I.

[0015]

[0016] Inert gas is introduced, the reaction temperature is controlled at 35-45° C., and stirring is performed for 14-20 hours to obtain the first polyurethane; wherein 10≤n≤20, 30≤b≤40, and b and n are integers.

[0017] The applicant adopts polyol compound Such as D-arabitol As a chain extender, it can react the terminal isocyanate group in the compound shown in Formula I with the hydroxyl group, thereby extending the main chain and making the flexible segment longer, reducing the content of the rigid segment, and increasing the flexibility of the first polyurethane.

[0018] In some embodiments, the solvent is one or more of toluene, dichloromethane, N,N-dimethylformamide, and tetrahydrofuran.

[0019] Preferably, the solvent is toluene.

[0020] In some embodiments, in the method for preparing the first polyurethane, the volume of the solvent is 3 to 7 times the mass of D-arabitol.

[0021] Preferably, in the preparation method of the first polyurethane, the volume of the solvent is 5 times the mass of D-arabitol.

[0022] In some embodiments, the defoaming agent is one or more of dimethicone, BYK-012, BYK-016, and BYK-141.

[0023] Preferably, the defoaming agent is dimethyl silicone oil.

[0024] In some embodiments, the method for preparing the compound represented by Formula I comprises the following steps:

[0025] S1. Heat the first polytetrahydrofuran to 100-120° C., then stir at a constant temperature for 30-40 minutes, and then cool to 70-90° C. for standby use;

[0026] S2. Dissolve m-phenylene diisocyanate and dibutyltin dilaurate in a solvent, and slowly drip into the reaction system of step S1 at a dripping rate of 4-6 mL / min. Raise the temperature to 70-90° C. and stir for 10-12 h to obtain the compound of formula I.

[0027] In some embodiments, in step S2, the volume of the solvent is 9 to 11 times the mass of m-phenylenediisocyanate.

[0028] Preferably, in step S2, the volume of the solvent is 10 times the mass of m-phenylenediisocyanate.

[0029] In some embodiments, the number average molecular weight of the first polytetrahydrofuran is 2000-3000.

[0030] In some embodiments, the molar ratio of the first polytetrahydrofuran to m-phenylenediisocyanate is 1:(0.9-1.1).

[0031] Preferably, the molar ratio of the first polytetrahydrofuran to m-phenylenediisocyanate is 1:1.

[0032] In some embodiments, the molar ratio of D-arabitol to m-phenylenediisocyanate is (0.2-0.3):1.

[0033] The applicant uses D-arabitol as a chain extender to reduce the hard segment content and improve the flexibility of the first polyurethane. In addition, by adjusting the molar ratio of D-arabitol to isocyanate, the two hydroxyl groups in D-arabitol can be polymerized with isocyanate, increasing the main bond structure and improving the flexibility of the first polyurethane. This makes the polyurethane wiper strip more suitable for floors of different specifications, improves its adhesion to the floor, and is less likely to scratch the floor.

[0034] In some embodiments, the mass of the dibutyltin dilaurate is 0.2-0.4% of the mass of the first polytetrahydrofuran.

[0035] Preferably, the mass of dibutyltin dilaurate is 0.3% of the mass of the first polytetrahydrofuran.

[0036] In some embodiments, the filler is one or more of cellulose microfibrils, nanocellulose crystals, and bacterial nanocellulose.

[0037] Preferably, the filler is nanocellulose crystals.

[0038] In some embodiments, in the first polyurethane layer, the mass of the filler is 1.5-2% of the mass of the first polyurethane.

[0039] Preferably, in the first polyurethane layer, the mass of the filler is 1.8% of the mass of the first polyurethane.

[0040] The applicant can improve the wear resistance of the first polyurethane by regulating the mass ratio of the filler to the first polyurethane; in addition, it can prevent the flexibility of the polyurethane from decreasing due to improper filler.

[0041] In some embodiments, the structural formula of the second polyurethane is:

[0042]

[0043] Wherein, 10≤n≤20, 10≤a≤20, and a and n are integers.

[0044] The second polyurethane structure of the present application contains a large number of hydrogen bonds and dynamic covalent bonds, which work synergistically to improve the tear resistance and self-repair ability of polyurethane.

[0045] In some embodiments, the method for preparing the second polyurethane comprises the following steps:

[0046] (1) 100 g (542.3 mmol) of cyanuric chloride was mixed with 500 mL of dichloromethane, and 20 g (569.3 mmol) of ammonium hydroxide was added dropwise at a rate of 3 mL / min. The mixture was stirred at 28°C for 13 min to obtain compound A;

[0047] (2) 80 g (484.8 mmol) of compound A in step (1) was dissolved in 560 mL of dichloromethane, cooled to 3 ° C, and 130.7 g (1066 mmol) of methyl 3-chloropropionate and 77 g (727.3 mmol) of sodium carbonate were slowly added to the system at the same time, the temperature was controlled at 5 ° C. After the addition was completed, the temperature was raised to 28 ° C and stirred for 11 hours to obtain compound B;

[0048] (3) 150 g (444.9 mmol) of compound B in step (2) was dissolved in 1200 mL of tetrahydrofuran, the solution was cooled to -5 ° C, 70.7 g (667.3 mmol) of sodium carbonate was added, and then 88.6 g (400.4 mmol) of 4-amino-2,6-di-tert-butylphenol and 62.6 g (400.4 mmol) of 2,2,6,6-tetramethylpiperidinamine were added, stirred for 35 min, heated to 70 ° C, and stirred for 21 h to obtain compound C;

[0049] (4) Dissolve 260 g (405 mmol) of compound C in step (3) and 58.4 g (1822.7 mmol) of hydrazine hydrate in 1300 mL of propylene glycol and stir at 30°C for 51 h to obtain compound D;

[0050] (5) heating 58 g (934.7 mmol) of the second polytetrahydrofuran to 110° C., stirring for 35 min, and cooling to 80° C. for later use;

[0051] (6) Dissolve 149.7 g (934.7 mmol) of m-phenylenediisocyanate and 0.13 g of dibutyltin dilaurate in 449 mL of N,N-dimethylacetamide, and slowly add dropwise to the reaction system of step (5) at a rate of 5 mL / min. Heat to 80° C. and stir for 9 h to obtain compound E.

[0052] (VII) Dissolve 240 g (373.9 mmol) of compound D in step (IV) in 8400 mL of N,N-dimethylacetamide, add the mixture to compound E in step (VI), introduce N2, control the reaction temperature to 40°C, and stir for 17 h to obtain a second polyurethane.

[0053] In some embodiments, the number average molecular weight of the second polytetrahydrofuran is 800-1500.

[0054] Another aspect of the present invention provides a method for preparing a double-layer wiper strip made of a polyurethane substrate, comprising the following steps:

[0055] (1) mixing the various components required for preparing the first polyurethane layer uniformly, and curing them in a casting mold at 100-120° C. to obtain the first polyurethane layer;

[0056] (2) uniformly mixing the raw materials required for preparing the second polyurethane layer, pouring the mixture onto the first polyurethane layer prepared in step (1), and curing the mixture at 100-120° C. to obtain a double-layer polyurethane;

[0057] (3) Demolding the double-layer polyurethane in step (2), pressing and ultrasonicating at 50-60° C., and then cutting to obtain a double-layer wiper strip based on a polyurethane substrate.

[0058] The polyurethane-based double-layer wiper strip of the present application consists of a first polyurethane layer and a second polyurethane layer. During its preparation process, the applicant bonds the two layers together by casting and curing, and then breaks and reorganizes the hydrogen bonds in the second polyurethane layer and the first polyurethane layer by heating, pressing and ultrasonication. Under the action of hydrogen bonds and receptors, the second polyurethane layer and the first polyurethane layer are tightly bonded to prevent the polyurethane-based double-layer wiper strip from being dislocated and separated during use.

[0059] In another aspect, the present invention provides an application of a polyurethane-based double-layer wiper strip, which can be used in wiper accessories of a floor scrubber.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] (1) The polyurethane-based double-layer wiper strip of the present invention has a double-layer structure, and by regulating the thickness of the first polyurethane layer and the second polyurethane layer, the polyurethane-based double-layer wiper strip can have good tear resistance and self-repairing properties without affecting the flexibility and wiping performance of the polyurethane.

[0062] (2) The present invention adopts a small molecule polyol as a chain extender for the first polyurethane, which can provide a hydrogen bond acceptor while reducing the content of the hard chain, thereby improving the flexibility of the first polyurethane layer; in addition, the wear resistance of the first polyurethane layer can be enhanced by adding fillers for compounding.

[0063] (3) The present invention utilizes hydrogen bonds and receptors in the first polyurethane layer and the second polyurethane layer, and adopts heating, pressing and ultrasonic methods to tightly bond the first polyurethane layer and the second polyurethane layer together, thereby preventing the wiper strip from being dislocated and separated when in use. DETAILED DESCRIPTION

[0064] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0065] In the following examples and comparative examples, the number average molecular weight of the first polytetrahydrofuran is 2538, and the number average molecular weight of the second polytetrahydrofuran is 1098, both of which were purchased from Xinjiang Meike Chemical Co., Ltd.

[0066] In the following examples and comparative examples, the preparation method of the second polyurethane comprises the following steps:

[0067] (1) 100 g (542.3 mmol) of cyanuric chloride was mixed with 500 mL of dichloromethane, and 20 g (569.3 mmol) of ammonium hydroxide was added dropwise at a rate of 3 mL / min. The mixture was stirred at 28°C for 13 min to obtain compound A;

[0068] (2) 80 g (484.8 mmol) of compound A in step (1) was dissolved in 560 mL of dichloromethane, cooled to 3 ° C, and 130.7 g (1066 mmol) of methyl 3-chloropropionate and 77 g (727.3 mmol) of sodium carbonate were slowly added to the system at the same time, the temperature was controlled at 5 ° C. After the addition was completed, the temperature was raised to 28 ° C and stirred for 11 hours to obtain compound B;

[0069] (3) 150 g (444.9 mmol) of compound B in step (2) was dissolved in 1200 mL of tetrahydrofuran, the solution was cooled to -5 ° C, 70.7 g (667.3 mmol) of sodium carbonate was added, and then 88.6 g (400.4 mmol) of 4-amino-2,6-di-tert-butylphenol and 62.6 g (400.4 mmol) of 2,2,6,6-tetramethylpiperidinamine were added, stirred for 35 min, heated to 70 ° C, and stirred for 21 h to obtain compound C;

[0070] (4) Dissolve 260 g (405 mmol) of compound C in step (3) and 58.4 g (1822.7 mmol) of hydrazine hydrate in 1300 mL of propylene glycol and stir at 30°C for 51 h to obtain compound D;

[0071] (5) heating 58 g (934.7 mmol) of the second polytetrahydrofuran to 110° C., stirring for 35 min, and cooling to 80° C. for later use;

[0072] (6) Dissolve 149.7 g (934.7 mmol) of m-phenylenediisocyanate and 0.13 g of dibutyltin dilaurate in 449 mL of N,N-dimethylacetamide, and slowly add dropwise to the reaction system of step (5) at a rate of 5 mL / min. Heat to 80° C. and stir for 9 h to obtain compound E.

[0073] (VII) 240 g (373.9 mmol) of compound D from step (IV) was dissolved in 8400 mL of N,N-dimethylacetamide, and the mixture was added to compound E from step (VI). N2 was introduced, the reaction temperature was controlled at 40°C, and the mixture was stirred for 17 h to obtain a second polyurethane with a number average molecular weight of Mn = 36302.

[0074] In the following examples and comparative examples, nanocellulose crystals were purchased from Zhejiang Jinjiahao Green Nanomaterials Co., Ltd.

[0075] Preparation Example 1

[0076] The preparation method of the first polyurethane comprises the following steps:

[0077] S1. Heat 100 g (39.4 mmol) of the first polytetrahydrofuran to 110° C., then stir at a constant temperature for 35 min, and cool to 80° C. for later use;

[0078] S2. Dissolve 6.3 g (39.4 mmol) of m-phenylenediisocyanate and 0.3 g of dibutyltin dilaurate in 63 mL of toluene, and slowly add dropwise to the reaction system of step S1 at a rate of 5 mL / min. Raise the temperature to 80° C. and stir for 11 h to obtain the compound of formula I.

[0079] S3. Dissolve 1.5 g (9.8 mmol) of D-arabitol in 7.5 mL of toluene, then add the D-arabitol dissolved in toluene to the compound represented by Formula I, introduce N2 gas, control the reaction temperature to 40°C, and stir for 17 hours to obtain the first polyurethane.

[0080] Preparation Example 2

[0081] The first polyurethane has the same specific implementation as that of Preparation Example 1, except that the amount of D-arabitol added is 4 g (26.3 mmol).

[0082] Preparation Example 3

[0083] The first polyurethane has the same specific implementation as that of Preparation Example 1, except that an equimolar amount of the second polytetrahydrofuran is used instead of the first polytetrahydrofuran.

[0084] Preparation Example 4

[0085] The first polyurethane has the same specific implementation as that of Preparation Example 1, except that an equal molar amount of 3,3'-dichloro-4,4'-diphenylmethanediamine is used instead of D-arabitol.

[0086] Example 1

[0087] This embodiment provides a double-layer wiper strip made of a polyurethane substrate, which includes a first polyurethane layer and a second polyurethane layer; the first polyurethane layer has a thickness of 4.5 mm; the second polyurethane layer has a thickness of 1.5 mm; the first polyurethane layer includes the following raw materials in parts by mass: 100 parts of a first polyurethane, 0.04 parts of dimethyl silicone oil, and 1.8 parts of nanocellulose crystals.

[0088] The first polyurethane was prepared according to Preparation Example 1.

[0089] The second polyurethane layer includes the following raw materials in parts by mass: 100 parts of second polyurethane, 0.04 parts of dimethyl silicone oil and 0.5 parts of nanocellulose crystals.

[0090] The method for preparing a double-layer wiper strip made of a polyurethane substrate of this embodiment includes the following steps:

[0091] (1) mixing the raw materials required for preparing the first polyurethane layer uniformly, and curing the mixture in a casting mold at 110° C. to obtain the first polyurethane layer;

[0092] (2) mixing the raw materials required for preparing the second polyurethane layer uniformly, pouring the mixture onto the first polyurethane layer prepared in step (1), and curing the mixture at 110° C. to obtain a double-layer polyurethane;

[0093] (3) Demolding the double-layer polyurethane in step (2), pressing and ultrasonicating at 55° C., and then cutting to obtain a double-layer wiper strip based on a polyurethane substrate.

[0094] Example 2

[0095] This embodiment provides a double-layer wiper strip made of a polyurethane substrate, which includes a first polyurethane layer and a second polyurethane layer; the first polyurethane layer has a thickness of 2 mm; the second polyurethane layer has a thickness of 1 mm; the first polyurethane layer includes the following raw materials in parts by mass: 100 parts of a first polyurethane, 0.04 parts of dimethyl silicone oil, and 1.8 parts of nanocellulose crystals.

[0096] The first polyurethane was prepared according to Preparation Example 1.

[0097] The second polyurethane layer includes the following raw materials in parts by mass: 100 parts of second polyurethane, 0.04 parts of dimethyl silicone oil and 0.5 parts of nanocellulose crystals.

[0098] The method for preparing a double-layer wiper strip made of a polyurethane substrate of this embodiment includes the following steps:

[0099] (1) mixing the raw materials of the first polyurethane layer uniformly, and curing them at 100° C. in a casting mold to obtain the first polyurethane layer;

[0100] (2) stirring and mixing the raw materials of the second polyurethane layer until uniform, pouring the mixture onto the first polyurethane layer in step (1), and curing the mixture at 100° C. to obtain a double-layer polyurethane;

[0101] (3) Demolding the double-layer polyurethane in step (2), pressing and ultrasonicating at 50° C., and then cutting to obtain a double-layer wiper strip based on a polyurethane substrate.

[0102] Example 3

[0103] This embodiment provides a double-layer wiper strip made of a polyurethane base material, which includes a first polyurethane layer and a second polyurethane layer; the first polyurethane layer has a thickness of 2 mm; the second polyurethane layer has a thickness of 1 mm; the first polyurethane layer includes the following raw materials in parts by mass: 80 parts of a first polyurethane, 0.02 parts of dimethyl silicone oil, and 1.2 parts of nanocellulose crystals.

[0104] The first polyurethane was prepared according to Preparation Example 1.

[0105] The second polyurethane layer includes the following raw materials in parts by weight: 80 parts of second polyurethane, 0.02 parts of dimethyl silicone oil, and 0.2 parts of nanocellulose crystals.

[0106] The present invention provides a method for preparing a double-layer wiper strip made of a polyurethane substrate, comprising the following steps:

[0107] (1) mixing the raw materials of the first polyurethane layer uniformly, and curing them at 120° C. in a casting mold to obtain the first polyurethane layer;

[0108] (2) mixing the raw materials of the second polyurethane layer uniformly, pouring the mixture onto the first polyurethane layer in step (1), and curing at 120° C. to obtain a double-layer polyurethane;

[0109] (3) Demolding the double-layer polyurethane in step (2), pressing and ultrasonicating at 60° C., and then cutting to obtain a double-layer wiper strip based on a polyurethane substrate.

[0110] Example 4

[0111] This embodiment provides a double-layer wiper strip made of a polyurethane base material, which includes a first polyurethane layer and a second polyurethane layer; the first polyurethane layer has a thickness of 8 mm; the second polyurethane layer has a thickness of 2 mm; the first polyurethane layer includes the following raw materials in parts by mass: 120 parts of a first polyurethane, 0.06 parts of dimethyl silicone oil, and 2.4 parts of nanocellulose crystals.

[0112] The first polyurethane was prepared according to Preparation Example 1.

[0113] The second polyurethane layer includes the following raw materials in parts by weight: 120 parts of second polyurethane, 0.06 parts of dimethyl silicone oil, and 0.8 parts of nanocellulose crystals.

[0114] The present invention provides a method for preparing a double-layer wiper strip made of a polyurethane substrate, comprising the following steps:

[0115] (1) mixing the raw materials of the first polyurethane layer uniformly, and curing them at 120° C. in a casting mold to obtain the first polyurethane layer;

[0116] (2) mixing the raw materials of the second polyurethane layer uniformly, pouring the mixture onto the first polyurethane layer in step (1), and curing at 120° C. to obtain a double-layer polyurethane;

[0117] (3) Demolding the double-layer polyurethane in step (2), pressing and ultrasonicating at 60° C., and then cutting to obtain a double-layer wiper strip based on a polyurethane substrate.

[0118] Example 5

[0119] This embodiment provides a double-layer wiper strip made of a polyurethane substrate. The specific implementation is the same as that of Example 1, except that the first polyurethane is prepared according to Preparation Example 2.

[0120] Example 6

[0121] This embodiment provides a double-layer wiper strip made of a polyurethane substrate. The specific implementation is the same as that of Example 1, except that the first polyurethane is prepared according to Preparation Example 3.

[0122] Example 7

[0123] This embodiment provides a double-layer wiper strip made of a polyurethane substrate. The specific implementation is the same as that of Example 1, except that the first polyurethane is prepared according to Preparation Example 4.

[0124] Example 8

[0125] This embodiment provides a double-layer wiper strip made of a polyurethane substrate. The specific implementation method is the same as that of Example 1, except that in step (3), the double-layer polyurethane is directly cut after demoulding to obtain the double-layer wiper strip made of a polyurethane substrate.

[0126] Example 9

[0127] This embodiment provides a wiper strip, and the specific implementation is the same as that of Example 1, except that the filler in the first polyurethane layer is 3 parts.

[0128] Comparative Example 1

[0129] This comparative example provides a wiper strip, and the specific implementation is the same as that of Example 1, except that the thickness of the second polyurethane layer is 4.5 mm.

[0130] Comparative Example 2

[0131] This comparative example provides a wiper strip, and the specific implementation is the same as that of Example 1, except that the thickness of the second polyurethane layer is 0.5 mm.

[0132] Performance testing:

[0133] (1) Hardness test: Shore hardness was tested in accordance with ISO 48-1994. The test instrument was a TIME54420 Shore hardness tester manufactured by Beijing Times Peak Technology Co., Ltd. The test temperature was 25°C and the humidity was 46%.

[0134] (2) Tear strength test: Tested according to GB / T529-2008 “Determination of tear strength of vulcanized rubber or thermoplastic rubber”;

[0135] (3) Tensile strength test and elongation at break test: Tested according to HG / T3849-2008 "Determination of tensile strength and elongation at break of hard rubber" standard;

[0136] (4) Wear resistance test: Tested according to DIN-53516-1987 "Testing of rubber and elastomers - determination of wear resistance" standard;

[0137] (5) Rebound rate: Tested according to BS903:partA8:1990 "Physical testing or rubber" standard.

[0138] The wiper strips obtained in the examples and comparative examples were tested according to the above method. The results are shown in Table 1.

[0139] Table 1

[0140]

[0141]

[0142] As can be seen from Table 1, the polyurethane-based double-layer wiper strips prepared in Examples 1 to 4 have moderate hardness and good tensile strength, elongation at break, wear resistance, and tear strength. In Example 5, due to the change in the molar ratio of D-arabitol to m-phenylenediisocyanate, the secondary alcohol in D-arabitol also participates in the reaction, shortening the main chain, resulting in an increase in the hardness of the first polyurethane layer, and a decrease in the tensile strength and elongation at break of the polyurethane-based double-layer wiper strip. Due to the increase in the hardness of the first polyurethane layer, the wear resistance of the polyurethane-based double-layer wiper strip is slightly improved. In Example 6, due to the use of a second polytetrahydrofuran instead of the first polytetrahydrofuran, the soft segment molecular weight of the first polyurethane is reduced, resulting in an increase in the hardness of the first polyurethane layer, which reduces the tensile strength, tensile strength at break, and rebound rate of the polyurethane-based double-layer wiper strip. However, due to the increase in the hardness of the first polyurethane layer, the wear resistance of the polyurethane-based double-layer wiper strip is slightly improved. In Example 7, 3,3'-dichloro-4,4'-diphenylmethanediamine is used instead of D-arabitol, thereby reducing the content of urethane groups and increasing the content of urea groups, resulting in a decrease in the rebound rate of the first polyurethane layer, but a slight improvement in the hardness and tear resistance of the double-layer wiper strip based on the polyurethane substrate; in Example 9, the ratio of the filler to the first polyurethane is changed, so that the tensile strength and elongation at break of the wiper strip are reduced, but the wear resistance is slightly improved; in Comparative Example 1, the thickness ratio of the first polyurethane layer to the second polyurethane layer is changed, so that the second tensile strength and elongation at break are increased, and the hardness of the polyurethane layer is increased, resulting in a slight decrease in the rebound rate of the double-layer wiper strip based on the polyurethane substrate, but a slight improvement in the tear resistance; in Comparative Example 2, the thickness of the second polyurethane layer is reduced, so the hardness of the second polyurethane layer is reduced, resulting in a decrease in the tear resistance of the double-layer wiper strip based on the polyurethane substrate, but a slight improvement in the rebound rate.

[0143] The double-layer wiper strips prepared in Example 1, Example 8 and Example 9 were respectively applied on a 700 square meter epoxy floor to sprinkle water and wipe water in the morning, noon and evening. The morphology of the wiper strips was observed after one month. The test results are shown in Table 2.

[0144] Table 2

[0145] Example 1 Example 8 Example 9 Morphological changes No change Double-layer separation There is corrosion and stickiness

[0146] As can be seen from Table 2, the polyurethane-based double-layer wiper strip of Example 1 is relatively stable during use. In Example 8, due to the change in the preparation method of the polyurethane-based double-layer wiper strip, the adhesion between the first polyurethane layer and the second polyurethane layer is low. After a long period of friction and rebound, the first polyurethane layer and the second polyurethane layer separate, affecting use. In Example 9, due to the change in the ratio of filler to the first polyurethane, the polyurethane-based double-layer wiper strip is in contact with water for a long time. The filler part separates and absorbs water, causing corrosion and stickiness in the polyurethane-based double-layer wiper strip, affecting use. Test results show that the polyurethane-based double-layer wiper strip prepared by the present invention has good tensile properties, elongation at break, and wear resistance. In addition, it also has high wear resistance and tear strength.

[0147] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A double-layer wiper strip made of polyurethane, characterized in that: The polyurethane-based double-layer wiper strip comprises a first polyurethane layer and a second polyurethane layer; The thickness of the first polyurethane layer is 2 to 4 times the thickness of the second polyurethane layer; The thickness of the second polyurethane layer is 1-2 mm; The raw materials for preparing the first polyurethane layer include the following components in parts by mass: 80-120 parts of the first polyurethane, 0.02-0.06 parts of the defoaming agent, and 1-3 parts of the filler; The raw materials for preparing the second polyurethane layer include the following components in parts by mass: 80 to 120 parts of the second polyurethane, 0.02 to 0.06 parts of a defoaming agent, and 0.2 to 0.8 parts of a filler; The preparation method of the first polyurethane comprises the following steps: dissolving D-arabitol in a solvent, and then adding the D-arabitol dissolved in the solvent to the compound shown in formula I. （Ⅰ）， The reaction is carried out under an inert environment while stirring, the reaction temperature is controlled to be 35-45° C., and the stirring is carried out for 14-20 hours to obtain a first polyurethane; wherein 10≤n≤20, 30≤b≤40, and b and n are integers; The preparation method of the compound represented by formula I comprises the following steps: S1. Heat the first polytetrahydrofuran to 100-120° C., then stir under constant temperature for 30-40 minutes, and then cool to 70-90° C. for standby use; S2. Dissolve m-phenylene diisocyanate and dibutyltin dilaurate in a solvent, and slowly drip into the reaction system of step S1 at a dripping rate of 4-6 mL / min. Heat to 70-90° C., and stir for 10-12 h to obtain the compound of formula I. The structural formula of the second polyurethane is: ； Wherein, 10≤n≤20, 10≤a≤20, a and n are integers; The number average molecular weight of the first polytetrahydrofuran is 2000 to 3000; The molar ratio of D-arabitol to m-phenylenediisocyanate is (0.2-0.3):1; The method for preparing the polyurethane-based double-layer wiper strip comprises the following steps: (1) Stirring and mixing the various components required for preparing the first polyurethane layer, and curing them at 100-120° C. in a casting mold to obtain the first polyurethane layer; (2) Stirring and mixing the raw materials required for preparing the second polyurethane layer, pouring the mixture onto the first polyurethane layer in step (1), and curing the mixture at 100-120° C. to obtain a double-layer polyurethane; (3) The double-layer polyurethane in step (2) is demolded, pressed and ultrasonically processed at 50-60°C, and then cut to obtain a double-layer wiper strip based on a polyurethane substrate.

2. The polyurethane-based double-layer wiper strip according to claim 1, characterized in that: The molar ratio of the first polytetrahydrofuran to m-phenylenediisocyanate is 1:(0.9-1.1).

3. The polyurethane-based double-layer wiper strip according to claim 1, characterized in that: In the first polyurethane layer, the mass of the filler is 1.5-2% of the mass of the first polyurethane.

4. The polyurethane-based double-layer wiper strip according to claim 1, characterized in that: The filler is one or more of cellulose microfibrils, nanocellulose crystals and bacterial nanocellulose.

5. A method for preparing a polyurethane-based double-layer wiper strip according to any one of claims 1 to 4, characterized in that: The steps include: (1) Stirring and mixing the various components required for preparing the first polyurethane layer, and curing them at 100-120° C. in a casting mold to obtain the first polyurethane layer; (2) Stirring and mixing the raw materials required for preparing the second polyurethane layer, pouring the mixture onto the first polyurethane layer in step (1), and curing the mixture at 100-120° C. to obtain a double-layer polyurethane; (3) The double-layer polyurethane in step (2) is demolded, pressed and ultrasonically processed at 50-60°C, and then cut to obtain a double-layer wiper strip based on a polyurethane substrate.

6. Use of a polyurethane-based double-layer wiper strip according to any one of claims 1 to 4, characterized in that: The polyurethane-based double-layer wiper strip is used in wiper accessories of floor scrubbers.

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