Self-repairing PU (polyurethane) and preparation method thereof

Abstract

The self-repairing PU sequentially comprises a coating layer, a PU surface layer, a PU foaming layer and a base cloth layer from top to bottom, a polyurethane prepolymer, a catalyst and dimethylglyoxime (a metal chelating agent) are packaged in a PU foaming layer through a microsphere packaging technology, when the material is damaged, microspheres are broken to release repairing components, a cross-linking reaction between the prepolymer and active substances (such as water and polyhydric alcohols) is triggered under the illumination or heating condition, scratches or holes are rapidly filled, and the service life of the material is prolonged. Manual intervention is not needed in the repairing process, and only external conditions (such as light / heat) are needed.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, in particular to a self-repairing PU and a preparation method thereof. Background Art

[0002] Polyurethane (PU) materials are widely used in many fields such as automobiles, construction, textiles, and medical due to their excellent wear resistance, chemical resistance, elasticity, and mechanical properties. As various industries continue to increase their requirements for material performance, self-healing polyurethane materials have gradually become a research hotspot.

[0003] Traditional polyurethane materials experience significant performance degradation after physical damage (such as scratches and cracks) and are unable to repair themselves, significantly limiting their application in applications where material integrity and durability are critical. For example, in automotive interior materials, scratches from daily use not only affect the appearance but can also accelerate material aging. Summary of the Invention

[0004] To achieve the above object, the present invention provides the following technical solution: a self-repairing PU, characterized in that it comprises, from top to bottom, a coating layer, a PU surface layer, a PU foam layer, and a base fabric layer;

[0005] The raw materials of the finishing layer include the following components in parts by weight: 40-60 parts of semi-bright matte surface treatment agent, 45-60 parts of matte surface treatment agent, 8-16 parts of hand feeling and wear resistance agent, 0.2-0.3 parts of defoaming agent, 0.2-0.3 parts of antibacterial agent, 0.8-1 parts of leveling agent, 5-7 parts of cross-linking agent, and 25-40 parts of industrial distilled water;

[0006] The raw materials of the PU surface layer include the following components by weight: 95-105 parts of PU resin, 10-35 parts of deionized water, and 7-30 parts of color paste;

[0007] The PU foam layer comprises the following components in parts by weight: 95-105 parts of PU resin, 10-35 parts of deionized water, 7-30 parts of color paste, 95-105 parts of solvent-free adhesive material A, 48-70 parts of solvent-free adhesive material B, 0.05-0.1 parts of microspheres, 0.18-0.3 parts of accelerator, 0.15-0.25 parts of leveling agent, and 35-50 parts of flame retardant;

[0008] The microspheres encapsulate mutually isolated polyurethane prepolymers and catalysts. When the microspheres are destroyed, the polyurethane prepolymers and catalysts mix, and external light and temperature accelerate the reaction speed of the prepolymers.

[0009] Preferably, the polyurethane prepolymer is generated by reacting m-xylylene diisocyanate (containing -NCO groups) with polytetrahydrofuran (containing -OH groups) at 60-80° C. and contains a urethane structure.

[0010] Preferably, the microspheres further include a catalyst stabilizer mixed with the catalyst.

[0011] Preferably, the catalyst stabilizer is dimethylglyoxime.

[0012] Preferably, the solvent-free adhesive material A is isocyanate, and the solvent-free adhesive material B is polyol.

[0013] The preparation steps of the above self-repairing PU are as follows:

[0014] S1: Preparation of PU surface layer: Deionized water and color paste were added to PU resin according to the weight ratio of the formula, and the mixture was stirred to obtain a PU mixture. The PU mixture was applied to the release paper with a coating thickness of 0.15±0.01mm and a speed of 15±3m / min. The temperature was increased in a stepwise manner to 90 / 100 / 110 / 120 / 130 / 135°C, and the drying time was 4 minutes. Each temperature was set for the same period of time to obtain the PU surface layer.

[0015] S2: Adding PU foam layer: According to the weight ratio of the formula, the raw materials of the PU foam layer are mixed evenly and applied to the surface of the PU surface layer. The coating thickness is 0.25±0.01mm. The vehicle speed is controlled at 10±1m / min. The temperature is stepped and heated and dried. The temperature is 100 / 100 / 100 / 110 / 125 / 125℃ in sequence. The drying time is 15min in total. Each temperature is set for the same time period to obtain a PU foam layer.

[0016] S3: Adding base fabric layer: Laminating one side of the PU foam layer to the base fabric, heating and drying in a stepwise manner, the temperature is: 135 / 135 / 135 / 140 / 140 / 140 / 140 / 140 / 145 / 145 / 145 / 145 / 145°C, drying time is 12 min, then separating the release paper, curling to make a PU semi-finished product, and then separating the release paper, the separated release paper has a PU texture surface to make a PU semi-finished product;

[0017] S4: Finishing layer: Mix the raw materials of the aqueous treatment layer evenly according to the weight ratio of the formula, and then use a roller coater to apply it to the PU surface layer side of the PU semi-finished product. The speed is controlled at 10±2m / min, and the temperature is stepped and heated and dried. The drying temperatures are 125 / 130 / 130 / 130 / 130℃, and the drying time is 2-3min. Curl after drying.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. Self-repair function: Through microsphere encapsulation technology, polyurethane prepolymer, catalyst, and dimethylglyoxime (metal chelating agent) are encapsulated in the foam layer. When the material is damaged, the microspheres rupture and release the repair components. Under light or heat conditions, a cross-linking reaction between the prepolymer and active substances (such as water and polyols) is triggered, rapidly filling the scratches or holes. The repair process requires no human intervention and only requires external conditions (such as light or heat) to trigger it.

[0020] 2. Improved safety and durability: Damage in small or high-risk areas (such as car interiors) can be repaired promptly, avoiding safety hazards. Extended life: The material can withstand 3-5 repair cycles, significantly extending the product's service life.

[0021] 3. Environmental protection advantage: Water-based resin and solvent-free adhesive are used to reduce volatile organic compound (VOC) emissions and reduce carbon footprint. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the material structure of the present invention.

[0023] In the figure: 1. Coating layer; 2. PU surface layer; 3. PU foam layer; 4. Base fabric layer. DETAILED DESCRIPTION

[0024] Table 1

[0025]

[0026] Example 1

[0027] From top to bottom, they are: coating layer, PU surface layer, PU foam layer (containing microspheres), and bamboo fiber base fabric layer.

[0028] Raw material formula of each layer (parts by weight)

[0029] Finishing layer: 40 parts of semi-bright matte surface treatment agent, 45 parts of matte surface treatment agent, 8 parts of hand feel and wear-resistant agent, 0.2 parts of defoaming agent, 0.2 parts of antibacterial agent, 0.8 parts of leveling agent, 5 parts of cross-linking agent, and 25 parts of industrial distilled water.

[0030] PU surface layer: 95 parts of PU resin, 10 parts of deionized water, 7 parts of color paste

[0031] PU foam layer: 95 parts of PU resin, 10 parts of deionized water, 7 parts of color paste, 95 parts of solvent-free adhesive material A (isocyanate), 48 parts of solvent-free adhesive material B (polyol), 0.05 parts of microspheres (encapsulating polyurethane prepolymer, catalyst and dimethylglyoxime), 0.18 parts of accelerator, 0.15 parts of leveling agent, 35 parts of flame retardant

[0032] Preparation process:

[0033] Preparation of PU surface layer: Add deionized water and color paste to PU resin according to the weight ratio of the formula, stir evenly to obtain a PU mixture, apply the PU mixture on the release paper, control the coating thickness at 0.15±0.01mm, control the vehicle speed at 15±3m / min, and heat and dry in a step-by-step manner at the following temperatures: 90 / 100 / 110 / 120 / 130 / 135°C, with a total drying time of 4 minutes. Set each temperature for the same time period to obtain the PU surface layer;

[0034] Adding PU foam layer: according to the weight ratio of the formula, mix the raw materials of the PU foam layer evenly, apply it to the surface of the PU surface layer, the coating thickness is 0.25±0.01mm, the speed is controlled at 10±1m / min, and the temperature is stepped heating and drying at 100 / 100 / 100 / 110 / 125 / 125℃ in sequence, and the drying time is a total of 15min. Each temperature is set for the same time period to obtain the PU foam layer;

[0035] Add base fabric layer: Lay one side of the PU foam layer on the base fabric, heat and dry in a step-by-step manner, with the temperatures being 135 / 135 / 135 / 140 / 140 / 140 / 140 / 140 / 145 / 145 / 145 / 145 / 145°C, and drying for 12 minutes. Then separate the release paper, curl it, and make a PU semi-finished product. Then separate the release paper, leaving one side of the separated release paper with a PU textured surface, and make a PU semi-finished product.

[0036] Finishing layer: Mix the raw materials of the aqueous treatment layer evenly according to the weight ratio of the formula, and then use a roller coater to apply it to the PU surface layer side of the PU semi-finished product. The speed is controlled at 10±2m / min. Heat and dry in a step-by-step manner. The drying temperatures are 125 / 130 / 130 / 130 / 130 / 130℃ in sequence, and the drying time is 2-3min. Set the same time period for each temperature, and curl it after drying.

[0037] Detection method:

[0038] 1. Tensile strength:

[0039] (1) Sample preparation: Prepare a rectangular sample with a length of 200 mm and a width of 50 mm.

[0040] (2) Test method:

[0041] The test was carried out in accordance with GB / T1040.3, using type 2 specimens, specimen marking spacing: 100 mm, and tensile speed: 100 mm / min.

[0042] (3) Presentation of test results

[0043] Warp 500N, weft 600N

[0044] 2. Tear strength:

[0045] (1) Sample preparation: Prepare a rectangular sample with a length of 200 mm and a width of 50 mm.

[0046] (2) Test method:

[0047] Conduct the test according to GB / T16578.1 and record the maximum tearing load of the specimen. Tensile speed: 200 mm / min.

[0048] (3) Presentation of test results

[0049] Warp 35N, weft 40N

[0050] 3. Self-repair capability test:

[0051] Use a blade to scratch the test leather with a depth of 1mm and a length of 100mm. Then, after exposure to light or letting it stand for a period of time under high temperature conditions (40°C), repeat the above tensile strength and tear strength tests. The measured results are: tensile strength in the warp direction ≥480N, ≥570N in the weft direction; tear strength: 32N in the warp direction, 36N in the weft direction, and the scratch is filled and repaired.

[0052] Example 2

[0053] From top to bottom, they are: coating layer, PU surface layer, PU foam layer (containing microspheres), and bamboo fiber base fabric layer.

[0054] Raw material formula of each layer (parts by weight)

[0055] Finishing layer: 60 parts of semi-bright matte surface treatment agent, 60 parts of matte surface treatment agent, 16 parts of hand feel and wear-resistant agent, 0.3 parts of defoaming agent, 0.3 parts of antibacterial agent, 1 part of leveling agent, 7 parts of cross-linking agent, and 40 parts of industrial distilled water.

[0056] PU surface layer: 105 parts PU resin, 35 parts deionized water, 30 parts color paste

[0057] PU foam layer: 105 parts of PU resin, 35 parts of deionized water, 30 parts of color paste, 105 parts of solvent-free adhesive material A (isocyanate), 70 parts of solvent-free adhesive material B (polyol), 0.1 parts of microspheres (encapsulating polyurethane prepolymer, catalyst and dimethylglyoxime), 0.3 parts of accelerator, 0.25 parts of leveling agent, 50 parts of flame retardant

[0058] The preparation process is the same as that in Example 1.

[0059] Detection method:

[0060] 1. Tensile strength:

[0061] (1) Sample preparation: Prepare a rectangular sample with a length of 200 mm and a width of 50 mm.

[0062] (2) Test method:

[0063] The test was carried out in accordance with GB / T1040.3, using type 2 specimens, specimen marking spacing: 100 mm, and tensile speed: 100 mm / min.

[0064] (3) Presentation of test results

[0065] Warp 503N, weft 605N

[0066] 2. Tear strength:

[0067] (1) Sample preparation: Prepare a rectangular sample with a length of 200 mm and a width of 50 mm.

[0068] (2) Test method:

[0069] Conduct the test according to GB / T16578.1 and record the maximum tearing load of the specimen. Tensile speed: 200 mm / min.

[0070] (3) Presentation of test results

[0071] Warp 35N, weft 40N

[0072] 3. Self-repair capability test:

[0073] Use a blade to scratch the test leather with a depth of 1mm and a length of 100mm. Then, after exposure to light or allowing it to stand for a period of time under high temperature conditions (40°C), repeat the above tensile strength and tear strength experiments. The measured results are: tensile strength: 495N in the warp direction and 600N in the weft direction; tear strength: 35N in the warp direction and 39N in the weft direction. The scratch is filled and repaired.

[0074] Example 3

[0075] From top to bottom, they are: coating layer, PU surface layer, PU foam layer (containing microspheres), and bamboo fiber base fabric layer.

[0076] Raw material formula of each layer (parts by weight)

[0077] Finishing layer: 50 parts of semi-bright matte surface treatment agent, 50 parts of matte surface treatment agent, 12 parts of hand feel and wear-resistant agent, 0.25 parts of defoaming agent, 0.25 parts of antibacterial agent, 0.9 parts of leveling agent, 6 parts of cross-linking agent, and 30 parts of industrial distilled water.

[0078] PU surface layer: 100 parts PU resin, 20 parts deionized water, 20 parts color paste

[0079] PU foam layer: 100 parts of PU resin, 20 parts of deionized water, 20 parts of color paste, 100 parts of solvent-free adhesive material A (isocyanate), 60 parts of solvent-free adhesive material B (polyol), 0.08 parts of microspheres (encapsulating polyurethane prepolymer, catalyst and dimethylglyoxime), 0.2 parts of accelerator, 0.2 parts of leveling agent, 40 parts of flame retardant

[0080] The preparation process is the same as that in Example 1.

[0081] Detection method:

[0082] 1. Tensile strength:

[0083] (1) Sample preparation: Prepare a rectangular sample with a length of 200 mm and a width of 50 mm.

[0084] (2) Test method:

[0085] The test was carried out in accordance with GB / T1040.3, using type 2 specimens, specimen marking spacing: 100 mm, and tensile speed: 100 mm / min.

[0086] (3) Presentation of test results

[0087] Warp 505N, weft 598N

[0088] 2. Tear strength:

[0089] (1) Sample preparation: Prepare a rectangular sample with a length of 200 mm and a width of 50 mm.

[0090] (2) Test method:

[0091] Conduct the test according to GB / T16578.1 and record the maximum tearing load of the specimen. Tensile speed: 200 mm / min.

[0092] (3) Presentation of test results

[0093] Warp 35N, weft 40N

[0094] 3. Self-repair capability test:

[0095] Use a blade to scratch the test leather with a depth of 1mm and a length of 100mm. Then, after exposure to light or allowing it to stand for a period of time under high temperature conditions (40°C), repeat the above tensile strength and tear strength experiments. The measured results are: tensile strength: 485N in the warp direction and 580N in the weft direction; tear strength: 34N in the warp direction and 37N in the weft direction. The scratches are filled and repaired.

[0096] Comparative Example 1

[0097] From top to bottom, they are: coating layer, PU surface layer, PU foam layer (containing microspheres), and bamboo fiber base fabric layer.

[0098] Raw material formula of each layer (parts by weight)

[0099] Finishing layer: 50 parts of semi-bright matte surface treatment agent, 50 parts of matte surface treatment agent, 10 parts of hand feel and wear-resistant agent, 0.25 parts of defoaming agent, 0.25 parts of antibacterial agent, 0.85 parts of leveling agent, 6 parts of cross-linking agent, and 30 parts of industrial distilled water.

[0100] PU surface layer: 100 parts PU resin, 20 parts deionized water, 15 parts color paste

[0101] PU foam layer: 100 parts of PU resin, 20 parts of deionized water, 15 parts of color paste, 100 parts of solvent-free adhesive material A (isocyanate), 60 parts of solvent-free adhesive material B (polyol), 0.2 parts of accelerator, 0.2 parts of leveling agent, 40 parts of flame retardant

[0102] Preparation process: same as Example 1.

[0103] Detection method:

[0104] 1. Tensile strength:

[0105] (1) Sample preparation: Prepare a rectangular sample with a length of 200 mm and a width of 50 mm.

[0106] (2) Test method:

[0107] The test was carried out in accordance with GB / T1040.3, using type 2 specimens, specimen marking spacing: 100 mm, and tensile speed: 100 mm / min.

[0108] (3) Presentation of test results

[0109] Warp ≥ 485N, weft ≥ 580N

[0110] 2. Tear strength:

[0111] (1) Sample preparation: Prepare a rectangular sample with a length of 200 mm and a width of 50 mm.

[0112] (2) Test method:

[0113] Conduct the test according to GB / T16578.1 and record the maximum tearing load of the specimen. Tensile speed: 200 mm / min.

[0114] (3) Presentation of test results

[0115] Longitudinal direction ≥34N, latitudinal direction ≥39N

[0116] 3. Self-repair capability test:

[0117] Use a blade to scratch the test leather with a depth of 1mm and a length of 100mm. Then, after exposure to light or allowing it to stand for a period of time under high temperature conditions (40°C), repeat the above tensile strength and tear strength tests. The measured results are: tensile strength in the warp direction ≥315N, weft direction ≥420N; tear strength: warp direction ≥22N, weft direction ≥28N. The scratches are not repaired.

[0118] Comparing Examples 1, 2, and 3 with Comparative Example 1, the following results are shown in Table 2:

[0119] Table 2

[0120]

[0121] In Examples 1, 2 and 3, the self-repairing function is achieved by microsphere technology. In Comparative Example 1, no microspheres are added and thus no repairing ability is achieved. In Example 2, the amount of microspheres added is higher than in Examples 1 and 3, and its self-repairing ability is relatively stronger.

Claims

1. A self-repairing PU, characterized in that: From top to bottom, it includes coating layer, PU surface layer, PU foam layer and base fabric layer; The raw materials of the finishing layer include the following components in parts by weight: 40-60 parts of semi-bright matte surface treatment agent, 45-60 parts of matte surface treatment agent, 8-16 parts of hand feeling and wear resistance agent, 0.2-0.3 parts of defoaming agent, 0.2-0.3 parts of antibacterial agent, 0.8-1 parts of leveling agent, 5-7 parts of cross-linking agent, and 25-40 parts of industrial distilled water; The raw materials of the PU surface layer include the following components by weight: 95-105 parts of PU resin, 10-35 parts of deionized water, and 7-30 parts of color paste; The PU foam layer comprises the following components in parts by weight: 95-105 parts of PU resin, 10-35 parts of deionized water, 7-30 parts of color paste, 95-105 parts of solvent-free adhesive material A, 48-70 parts of solvent-free adhesive material B, 0.05-0.1 parts of microspheres, 0.18-0.3 parts of accelerator, 0.15-0.25 parts of leveling agent, and 35-50 parts of flame retardant; The microspheres encapsulate mutually isolated polyurethane prepolymers and catalysts. When the microspheres are destroyed, the polyurethane prepolymers and catalysts mix, and external light and temperature accelerate the reaction speed of the prepolymers.

2. The self-repairing PU according to claim 1, characterized in that: The polyurethane prepolymer is a prepolymer containing a carbamate structure, which is generated by reacting m-xylylene diisocyanate with polytetrahydrofuran at 60-80°C.

3. The self-repairing PU according to claim 2, characterized in that: The microspheres also include a catalyst stabilizer mixed with the catalyst.

4. The self-repairing PU according to claim 3, characterized in that: The catalyst stabilizer is dimethylglyoxime.

5. The self-repairing PU according to claim 1, characterized in that: The solvent-free adhesive material A is isocyanate, and the solvent-free adhesive material B is polyol.

6. The self-repairing PU according to claim 1, characterized in that: The base fabric layer is a bamboo fiber base fabric.

7. A method for preparing the self-repairing PU according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: Preparation of PU surface layer: Deionized water and color paste were added to PU resin according to the weight ratio of the formula, and the mixture was stirred to obtain a PU mixture. The PU mixture was applied to the release paper with a coating thickness of 0.15±0.01mm and a speed of 15±3m / min. The temperature was increased in a stepwise manner to 90 / 100 / 110 / 120 / 130 / 135°C, and the drying time was 4 minutes. Each temperature was set for the same period of time to obtain the PU surface layer. S2: Adding PU foam layer: According to the weight ratio of the formula, the raw materials of the PU foam layer are mixed evenly and applied to the surface of the PU surface layer. The coating thickness is 0.25±0.01mm. The vehicle speed is controlled at 10±1m / min. The temperature is stepped and heated and dried. The temperature is 100 / 100 / 100 / 110 / 125 / 125℃ in sequence. The drying time is 15min in total. Each temperature is set for the same time period to obtain a PU foam layer. S3: Adding base fabric layer: Lay one side of the PU foam layer on the base fabric, and heat and dry it in a step-by-step manner, with the temperatures being 135 / 135 / 135 / 140 / 140 / 140 / 140 / 140 / 145 / 145 / 145 / 145 / 145°C, and the drying time being 12 min. Set each temperature for the same time period, then separate the release paper, curl it, and make a PU semi-finished product. Then separate the release paper, leaving one side of the separated release paper with a PU texture surface, to make a PU semi-finished product. S4: Finishing layer: Mix the raw materials of the aqueous treatment layer evenly according to the weight ratio of the formula, and then use a roller coater to apply it to the PU surface layer side of the PU semi-finished product. The speed is controlled at 10±2m / min, and the temperature is stepped and heated and dried. The drying temperatures are 125 / 130 / 130 / 130 / 130 / 130℃, and the drying time is 2-3min. Each temperature is set for the same time period, and curled after drying.

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