A thermoplastic polyolefin interior skin with high chemical resistance and its preparation method

Abstract

The present invention discloses a thermoplastic polyolefin interior trim skin with high chemical resistance and a preparation method thereof, relating to the technical field of laminated structure polymer materials, aiming to improve various chemical resistance properties of the TPO interior trim skin; the present invention includes a surface coating top layer, a surface coating middle layer, a surface coating bottom layer, a TPO top layer, a TPO middle layer, and a TPO bonding layer sequentially arranged from outside to inside on the surface of a substrate, wherein the surface coating top layer is dense for anti-permeation, the surface coating middle layer is for barrier, and the surface coating bottom layer is for improving the adhesion between the coating and the TPO; the TPO top layer, the TPO middle layer, and the TPO bonding layer are co-extruded and dynamically vulcanized during the extrusion process, and a cross-linking agent is added to the TPO middle layer; the preparation process of the present invention is simple and easy to operate, and the prepared interior trim skin product has excellent resistance to DEET, organic solvents, acidic substances, alkaline substances, and oil stains.

Description

Technical Field

[0001] The invention relates to the technical field of layered structure polymer materials, in particular to a thermoplastic polyolefin interior skin with high chemical resistance and a preparation method thereof. Background Art

[0002] Thermoplastic polyolefin (TPO for short) is an elastomeric material composed of two components: rubber and polyolefin. Its products have excellent weather resistance, oil resistance, ozone resistance, and UV resistance. They have excellent dynamic fatigue resistance, good wear resistance, high tear strength, and low compression permanent deformation. They also have the characteristics of simple processing technology, short cycle, low energy consumption, and no "three wastes". As a rubber replacement product, it is widely used in automobile production, building materials, transportation, wires and cables, medical equipment, electronic appliances, sports equipment, printing and dyeing and other industries. It is a new material with great development potential.

[0003] Traditional TPO surfaces are prone to swelling, discoloration, or mechanical property degradation when exposed to oil, detergent, DEET, organic solvents, or acidic / alkaline substances, which greatly affects the service life of TPO products. Existing technologies usually only improve one aspect, and it is difficult to take into account multiple chemical resistance properties. Most of them improve the oil resistance of other materials, and there are very few improvements on TPO materials. Therefore, a thermoplastic polyolefin interior surface with high chemical resistance and a preparation method thereof are urgently needed to solve this problem. Summary of the invention

[0004] The object of the present invention is to provide a thermoplastic polyolefin interior skin with high chemical resistance and a preparation method thereof, so as to improve the various chemical resistance of the TPO interior skin.

[0005] To achieve the above object, the present invention provides the following technical solutions: a thermoplastic polyolefin interior skin with high chemical resistance, comprising a surface coating surface layer, a surface coating middle layer, a surface coating bottom layer, a TPO surface layer, a TPO middle layer, and a TPO bonding layer arranged in sequence from outside to inside on the surface of a substrate, wherein the surface coating surface layer is dense for anti-penetration, the surface coating middle layer is used for barrier, and the surface coating bottom layer is used for improving the adhesion between the coating and TPO;

[0006] The components of the surface coating layer are calculated by weight, including: 60-80 parts of silicone resin, 5-10 parts of nano-silicon dioxide filler, 5-10 parts of organic silicon wear-resistant additive, 0-5 parts of perfluoroalkyl compound, 5-15 parts of cross-linked acrylic resin, and 3-7 parts of multifunctional isocyanate cross-linking agent;

[0007] The middle layer of the surface coating adopts a cross-linked fluorocarbon / polyurethane composite coating;

[0008] The surface coating base layer is made of chlorinated polyolefin;

[0009] The components of the TPO top layer, by weight parts, include: 100 parts of high-density thermoplastic polyolefin, 1-5 parts of fluorinated polymer, and 0.5-5 parts of anti-migration antioxidant;

[0010] The components of the middle layer of the TPO layer, by weight parts, include: 100 parts of thermoplastic polyolefin elastomer and 2-8 parts of nano-silica;

[0011] The components of the TPO bonding layer, by weight parts, include: 100 parts of thermoplastic polyolefin elastomer and 5-10 parts of maleic anhydride grafted POE;

[0012] The TPO top layer, the middle layer of the TPO layer, and the TPO bonding layer are co-extruded and dynamically vulcanized during the extrusion process. A cross-linking agent is added to the middle layer of the TPO layer, and the cross-linking degree is controlled at 10%-30%.

[0013] Preferably, the density of the high-density thermoplastic polyolefin is greater than 0.95 g / cm 3 , the density of the thermoplastic polyolefin elastomer is lower than that of the high-density thermoplastic polyolefin, and the same thermoplastic polyolefin elastomer is used for the middle layer of the TPO layer and the TPO bonding layer.

[0014] Preferably, the thicknesses of the TPO top layer and the middle layer of the TPO layer are 0.1-0.3 mm respectively.

[0015] Preferably, in the cross-linked fluorocarbon / polyurethane composite coating used for the middle layer of the surface coating, the mass ratio of cross-linked fluorocarbon to polyurethane is 1:9.

[0016] Preferably, the substrate is made of polyethylene, polypropylene foaming material or PET base fabric.

[0017] Another technical solution provided by the present invention: A preparation method of a thermoplastic polyolefin interior trim skin with high chemical resistance performance, including the following contents:

[0018] The TPO top layer, the middle layer of the TPO layer, and the TPO bonding layer are co-extruded and dynamically vulcanized during the extrusion process. A cross-linking agent is added to the middle layer of the TPO layer, and the cross-linking degree is controlled at 10%-30%. After multi-layer synchronous extrusion, it is hot-pressed and shaped to obtain the TPO layer;

[0019] The surface of the TPO layer is modified by ionized gas to generate nano-scale etching and polar groups, increasing the surface energy to more than 60 mN / m and enhancing the coating adhesion. The bottom layer of the surface coating, the middle layer of the surface coating, and the top layer of the surface coating are sequentially coated on the surface of the TPO top layer through a printing process. After each coating, it is dried and then the next layer is coated until the three-layer coating and drying are completed;

[0020] Finally, the substrate is laminated on the surface of the TPO adhesive layer by embossing.

[0021] Preferably, when co-extrusion molding, the back roll gap is controlled to be 0.5±0.1 mm, the back roll pressure is 8±2 Mpa, and the temperature is 180-210 °C.

[0022] Preferably, the drying temperatures after coating the bottom layer, middle layer, and top layer of the surface coating are 120±10 °C respectively, and the drying time after each layer coating is 2-3 min.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] For the thermoplastic polyolefin interior trim skin with high chemical resistance performance, through the structural design of three layers of surface coating and three layers of TPO layer, the chemical resistance performance of the interior trim skin is better improved. Among them, the top layer of the surface coating is dense and not easy to penetrate, and the silicone resin used further improves the chemical resistance performance of various types. The middle layer of the surface coating plays a barrier role, and the bottom layer of the surface coating can improve the adhesion with the TPO layer. The degree of tight combination also affects the chemical resistance performance of the interior trim skin. The TPO layer adds a fluorinated polymer in the top layer closest to the surface coating, which can improve the chemical resistance performance of the TPO layer itself and can serve as another barrier after the protection of the surface coating fails. An anti-migration antioxidant is also added to the top layer of the TPO layer. In addition to improving the anti-discoloration performance under normal environments, it can further reduce the impact of chemicals on its mechanical properties. The elastomer in the middle layer of the TPO layer is added with nano-silica, which can increase hardness, fill micropores, and further reduce the penetration of chemicals to the lower layer. The TPO adhesive layer is added with maleic anhydride grafted POE, which has good compatibility with polyolefin, good processing performance, saturated double bonds resistant to aging, and can also improve the toughening effect of the adhesive layer, and has a certain improvement effect on the swelling after being affected by chemicals. Although it cannot provide much help in resisting chemicals, it can reduce the impact of chemical erosion on the performance of the interior trim skin;

[0025] In addition, the preparation method of a thermoplastic polyolefin interior trim skin with high chemical resistance performance of the present invention has simple and easy-to-operate steps. The preparation process only requires three coating and drying operations after multi-layer co-extrusion. Compared with the prior art process, it does not add too many unit operations, nor does it require new equipment, and the raw material cost is relatively low, the production cost is easy to control, the prepared product has excellent chemical resistance performance for various chemicals, and is relatively environmentally friendly. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the positional relationship of the interior trim skin structure of the present invention.

[0027] In the figure: 1. Surface coating top layer; 2. Surface coating middle layer; 3. Surface coating bottom layer; 4. TPO top layer; 5. TPO middle layer; 6. TPO bonding layer; 7. Substrate. Detailed implementation mode

[0028] In order to obtain a thermoplastic polyolefin interior skin with excellent performance in terms of DEET resistance, organic solvent resistance, acid substance resistance, alkaline substance resistance, and oil stain resistance, the present invention proposes the following solutions: Refer to Figure 1 , a thermoplastic polyolefin interior skin with high chemical resistance performance, including a surface coating top layer, a surface coating middle layer, a surface coating bottom layer, a TPO top layer, a TPO middle layer, and a TPO bonding layer sequentially arranged from outside to inside on the surface of a substrate (which can be made of polyethylene, polypropylene foaming material, or PET base fabric, etc.). The surface coating top layer is dense for anti-permeation, the surface coating middle layer is for blocking, and the surface coating bottom layer is for improving the adhesion between the coating and TPO;

[0029] The components of the surface coating top layer, by weight, include: 60 - 80 parts of silicone resin, 5 - 10 parts of nano-silica filler, 5 - 10 parts of silicone wear-resistant auxiliary agent, 0 - 5 parts of perfluoroalkyl compound, 5 - 15 parts of cross-linked acrylic resin, and 3 - 7 parts of multi-functional isocyanate cross-linking agent (such as HDI trimer);

[0030] The surface coating middle layer adopts a cross-linked fluorocarbon / polyurethane composite coating;

[0031] The surface coating bottom layer adopts chlorinated polyolefin (CPO);

[0032] The components of the TPO top layer, by weight, include: 100 parts of high-density thermoplastic polyolefin, 1 - 5 parts of fluorinated polymer (such as polyvinylidene fluoride PVDF), and 0.5 - 5 parts of anti-migration antioxidant (such as hindered amine);

[0033] The components of the TPO middle layer, by weight, include: 100 parts of thermoplastic polyolefin elastomer and 2 - 8 parts of nano-silica;

[0034] The components of the TPO bonding layer, by weight, include: 100 parts of thermoplastic polyolefin elastomer and 5 - 10 parts of maleic anhydride grafted POE;

[0035] The TPO top layer, the TPO middle layer, and the TPO bonding layer are co-extruded and dynamically vulcanized during the extrusion process. A cross-linking agent is added to the TPO middle layer, and the cross-linking degree is controlled at 10% - 30%.

[0036] The TPO top layer should be a high-density TPO layer. Specifically, the density of the high-density thermoplastic polyolefin is preferably greater than 0.95 g / cm 3, correspondingly, the density of the thermoplastic polyolefin elastomer in the middle layer of the TPO layer and the TPO adhesive layer is lower than that of the high-density thermoplastic polyolefin; the thermoplastic polyolefin elastomer used in the TPO adhesive layer can further use the same material as the thermoplastic polyolefin elastomer in the middle layer of the TPO layer, with better performance, but different materials can also be used.

[0037] In a preferred embodiment, the thicknesses of the top layer and the middle layer of the TPO layer are 0.1 - 0.3 mm respectively.

[0038] In the crosslinked fluorocarbon / polyurethane composite coating used in the middle layer of the surface coating, the mass ratio of crosslinked fluorocarbon to polyurethane is 1:9.

[0039] A preparation method of a thermoplastic polyolefin interior trim skin with high chemical resistance includes the following:

[0040] The top layer of the TPO layer, the middle layer of the TPO layer, and the TPO adhesive layer are co-extruded and dynamically vulcanized during the extrusion process. A crosslinking agent is added to the middle layer of the TPO layer, and the crosslinking degree is controlled at 10% - 30%. After multi-layer synchronous extrusion, it is heat-pressed and shaped to obtain the TPO layer;

[0041] The surface of the TPO layer is modified by ionized gas (such as argon, oxygen) to generate nano-scale etching and polar groups (-OH, -COOH), increasing the surface energy to more than 60 mN / m and enhancing the coating adhesion; the bottom layer of the surface coating, the middle layer of the surface coating, and the top layer of the surface coating are successively coated on the surface of the top layer of the TPO layer through a printing process. After each coating, it is dried and then the next layer is coated until the three layers are coated and dried;

[0042] Finally, the substrate is laminated on the surface of the TPO adhesive layer by embossing.

[0043] During co-extrusion molding, the back roll gap is controlled at 0.5 ± 0.1 mm, the back roll pressure is 8 ± 2 Mpa, and the temperature is 180 - 210 °C.

[0044] The drying temperatures after coating the bottom layer of the surface coating, the middle layer of the surface coating, and the top layer of the surface coating are 120 ± 10 °C respectively, and the drying time after each coating is 2 - 3 min.

[0045] The following further illustrates the solution of the present invention through several examples and comparative examples. It should be understood that the following examples are only part rather than all examples of the present invention;

[0046] In the following examples and comparative examples:

[0047] Surface coating top layer: The silicone resin uses Dainichi Seika D-5591M, the nano-silica filler uses Yamei Nano SiO2-N-03, the silicone wear-resistant additive uses Dow Corning DC51, the perfluoroalkyl compound uses perfluorohexylethylene 25291-17-2 from Sichuan Shangfu Technology, the crosslinked acrylic resin uses Rom LP65 / 12N from Germany, and the polyfunctional isocyanate crosslinking agent uses Lanxess Trixene® series;

[0048] The ordinary resin used in the comparative example uses Stahl WF-3681;

[0049] Surface coating middle layer: The crosslinked fluorocarbon / polyurethane composite coating uses Shanghai Tiger Tech-9606-50 / Stahl RU-92-605;

[0050] Surface coating bottom layer: The chlorinated polyolefin uses Nippon Paper Industries 350S;

[0051] TPO top layer: The high-density thermoplastic polyolefin uses Basel HSBMR246, the fluorinated polymer uses PVDF of Solvay Solef 1008, and the anti-migration antioxidant uses BASF Irganox 1010;

[0052] TPO middle layer: The thermoplastic polyolefin elastomer uses ExxonMobil 6202, the nano-silica uses Wacker HDK H30; The crosslinking agent added to the TPO middle layer uses Dow Chemical 8150;

[0053] TPO adhesive layer: The thermoplastic polyolefin elastomer uses ExxonMobil 6202, and the maleic anhydride grafted POE uses ExxonMobil PE1040.

[0054] Examples 1 to 9 and Comparative Examples 1 to 4 adopt the same preparation method and parameter control. Among them, the temperature during coextrusion molding is controlled at about 195°C, the drying temperature after surface coating is controlled at about 120°C, and each layer is dried for 2 minutes after coating.

[0055] For Comparative Examples 5 and 6, the surface coating temperature and drying time are the same as those in the examples. Double-layer coextrusion is used for coextrusion, and the parameters are kept the same as those in the examples to control variables as much as possible.

[0056] In addition, in Table 1-3 below, the weight parts of the components between different functional layers of the same example are also in proportion. For example, the silicone resin and the chlorinated polyolefin in Example 1 are 60:100.

[0057] Table 1 Raw material weight part ratio of Examples 1 to 5

[0058]

[0059] Table 2 Proportion of parts by weight of raw materials for Examples 6 to 9 and Comparative Example 1

[0060]

[0061] Table 3 Proportion of parts by weight of raw materials for Comparative Examples 2 to 6

[0062]

[0063] The DEET resistance test is carried out using the following steps:

[0064] Sampling size: 2 pieces of 10×10 mm, 1 as the test sample and 1 as the pre-test sample;

[0065] For the coating material, use a sharp razor blade X to score (about 30 mm on each side) on the surface of the specimen. The scoring must penetrate the coating into the substrate.

[0066] Step 1: First, place the test sample in a circulating oven for pre-treatment, and the pre-treatment conditions are 85°C for 1 hour.

[0067] Step 2: Within 30 seconds after taking out the pre-treated sample, use a syringe or pipette to directly apply 0.35±0.05 mL of the test solution of DEET solution with a concentration greater than 99% to the center of the sample, and place the sample in an 85°C air-circulating oven for 1 hour of testing.

[0068] Step 3: After completion, wipe off the excess liquid, place the sample at room temperature for 1 hour, rinse the sample with a mild detergent (70% isopropyl alcohol solution) and gently pat dry.

[0069] First evaluation: Under the CIE D65 standard light source, compare and evaluate the color change of the test sample and the pre-test sample, and evaluate according to the ISO-105-A02 standard. Requirements: The color change level is not less than 4 levels.

[0070] Second evaluation: 24 hours after the first evaluation test, repeat the first evaluation step, and the color change level is not less than 4 levels (there is no requirement for the difference between the two results, as long as both are not less than 4 levels. The data in the following table is based on the results of the second evaluation).

[0071] Solvent resistance test:

[0072] a) Test method: 1 ml (about 18 - 23 drops) of artificial sweat, 0.5% soapy water, No. 92 gasoline, and window glass washing liquid were respectively dropped onto different positions on the surface of the sample, left standing at room temperature for 5 minutes (for painted interior parts, placed for 1 minute), then a folded white cotton cloth was wiped back and forth 10 times within a length range of 50 mm, and then the sample was placed in an environment of (23 ± 2) °C and (50 ± 3)% RH for 24 h.

[0073] b) Test results: The appearance of the wiped position of the sample was evaluated, and at the same time, the staining situation of the white cotton cloth was evaluated according to GB 251.

[0074] The acid and alkali resistance test was carried out according to GB / T 3920 for 500 rubs and the gray scale was evaluated (ISO105 - A02).

[0075] Oil resistance test: Wipe the surface of the skin with a cloth impregnated with liquid paraffin used in the oil resistance test, and after wiping, carry out a cycle test {(40 °C × 80% RH × 20 h → 20 °C × 50% RH × 4 h) × 3 times. After the test, check whether there is any abnormality on the surface and evaluate the gray scale (ISO105 - A02).

[0076] The above evaluation requirements are all ≥ 4 to be qualified products. The test results are shown in Table 4 below:

[0077] Table 4 Chemical resistance test results of examples and comparative examples

[0078]

[0079] The above are only the preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope defined by the claims.

[0080] The parts not detailed in the present invention are all well - known technologies to those skilled in the art.

Claims

1. A thermoplastic polyolefin interior skin with high chemical resistance performance, characterized in that: It includes a surface coating surface layer, a surface coating middle layer, a surface coating bottom layer, a TPO surface layer, a TPO middle layer, and a TPO bonding layer, which are arranged on the surface of the substrate from the outside to the inside in sequence, wherein the surface coating surface layer is dense for anti-penetration, the surface coating middle layer is used for blocking, and the surface coating bottom layer is used for improving the adhesion between the coating and TPO; The components of the surface coating surface layer include, by weight: 60-80 parts of silicone resin, 5-10 parts of nano-silicon dioxide filler, 5-10 parts of organic silicon wear-resistant additive, 0-5 parts of perfluoroalkyl compound, 5-15 parts of cross-linked acrylic resin, and 3-7 parts of multifunctional isocyanate cross-linking agent; The middle layer of the surface coating adopts a cross-linked fluorocarbon / polyurethane composite coating; The bottom layer of the surface coating is made of chlorinated polyolefin; The components of the TPO surface layer are calculated by weight: 100 parts of high-density thermoplastic polyolefin, 1-5 parts of fluorinated polymer, and 0.5-5 parts of anti-migration antioxidant; The components of the middle layer of the TPO layer are calculated by weight, including: 100 parts of thermoplastic polyolefin elastomer and 2-8 parts of nano silicon dioxide; The components of the TPO bonding layer are calculated by weight and include: 100 parts of thermoplastic polyolefin elastomer, 5-10 parts of maleic anhydride grafted POE; The TPO surface layer, the TPO middle layer and the TPO bonding layer are co-extruded and dynamically vulcanized during the extrusion process. A cross-linking agent is added to the TPO middle layer to control the cross-linking degree to be 10%-30%.

2. The thermoplastic polyolefin interior skin with high chemical resistance performance according to claim 1, characterized in that: The density of the high-density thermoplastic polyolefin is greater than 0.95 g / cm 3 , the density of the thermoplastic polyolefin elastomer is lower than that of the high-density thermoplastic polyolefin, and the same thermoplastic polyolefin elastomer is used for the layer and the TPO adhesive layer in the TPO layer.

3. The thermoplastic polyolefin interior trim skin with high chemical resistance performance according to claim 1, characterized in that: The thickness of the TPO surface layer and the TPO middle layer are 0.1-0.3 mm respectively.

4. The thermoplastic polyolefin interior skin with high chemical resistance performance according to claim 1, wherein: In the cross-linked fluorocarbon / polyurethane composite coating used in the middle layer of the surface coating, the mass ratio of cross-linked fluorocarbon to polyurethane is 1:

9.

5. A thermoplastic polyolefin interior skin with high chemical resistance performance according to claim 1, characterized in that: The substrate is made of polyethylene, polypropylene foam material or PET base cloth.

6. A method for preparing a thermoplastic polyolefin interior skin with high chemical resistance as described in any one of claims 1 to 5, characterized in that, Includes the following: The TPO surface layer, the TPO middle layer and the TPO bonding layer are co-extruded, and are dynamically vulcanized during the extrusion process. A cross-linking agent is added to the TPO middle layer to control the cross-linking degree to be 10%-30%. After the multiple layers are extruded simultaneously, they are hot-pressed and shaped to obtain the TPO layer. The surface of the TPO layer is modified by ionized gas to generate nano-scale etching and polar groups, increase the surface energy to more than 60mN / m, and enhance the adhesion of the coating; The bottom layer of the surface coating, the middle layer of the surface coating and the top layer of the surface coating are sequentially coated on the surface of the TPO layer by a printing process. Each layer is coated, dried and then the next layer is coated until the three layers are coated and dried. Finally, the substrate is compounded on the surface of the TPO bonding layer by embossing.

7. The preparation method according to claim 6, characterized in that: During the co-extrusion molding, the back roller gap is controlled to be 0.5±0.1 mm, the back roller pressure is controlled to be 8±2 MPa, and the temperature is controlled to be 180-210°C.

8. The preparation method according to claim 6, wherein: The post-coating drying temperatures of the surface coating bottom layer, the surface coating middle layer and the surface coating top layer are 120±10° C. respectively, and the post-coating drying time of each layer is 2-3 minutes.

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