Acrylic resin for interior and exterior plastic parts of automobile and preparation method of acrylic resin

Abstract

The invention discloses acrylic resin for automobile interior and exterior plastic parts and a preparation method of the acrylic resin. The acrylic resin comprises the following raw materials in percentage by weight: 0.5 wt% of methacrylic acid, 35-39 wt% of methyl methacrylate, 7-11 wt% of butyl methacrylate, 13-17 wt% of hydroxyethyl methylacrylate, 1-5 wt% of butyl acrylate, 1-5 wt% of glycidyl methacrylate, 0.5 wt% of trihydroxypropane triacrylate, 0.5-1.5 wt% of peroxide-2-ethylhexyl ester, 0.5-1.5 wt% of 1, 1-di-tert-butylperoxide-3, 5, 6-trimethyl-1, 3-pentanediol monoisobutyrate, 0.5-1.5 wt% of 1, 1-di-tert-butylperoxide-3, 5, 6-trimethyl-1, 3-pentanediol monoisobutyrate, 0.5-1.5 wt% of 1, 1- The additive comprises the following components in percentage by weight: 0.1 to 0.5 percent of 1, 3, 5-trimethylcyclohexane, 15 to 20 percent of butyl acetate and 10 to 15 percent of propylene glycol methyl ether acetate. According to the acrylic resin provided by the invention, the finally obtained resin can have the characteristics of excellent hardness, wear resistance, scratch resistance, weather resistance, chemical resistance and the like by controlling the dosage proportion of each component, the surface performance of a coating can be effectively improved, the adhesive force can be increased, and water vapor permeation can be effectively prevented.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to an acrylic resin for automobile interior and exterior plastic parts and a preparation method thereof. Background Art

[0002] With the development of the economy, people's living standards have been significantly improved. This improvement is not only reflected in the great enrichment of basic material life, but also in the continuous improvement of people's pursuit of quality of life. The optimization of travel methods is a typical manifestation of this. More and more people choose to buy cars as their daily means of transportation. The automobile industry has ushered in a period of rapid development, and automobile production has increased year by year, which has also directly led to a continuous increase in demand for automobiles. As an important part of the interior space of a car, automotive interior parts play an important role in improving the overall aesthetics, comfort and functionality of the car. Automotive interior parts mainly include dashboards, door panels, ceilings and other components.

[0003] In the production process of modern automobile interior parts, plastic injection molding technology is mostly used. This is because plastic materials have many advantages such as light weight, easy molding, and relatively low cost. Among them, polypropylene (PP) is widely used in the manufacture of basic structural parts of automobile interior parts due to its good mechanical properties, heat resistance and chemical stability; ABS (acrylonitrile-butadiene-styrene copolymer) is favored in the manufacture of some interior parts that require higher structural strength due to its excellent plasticity, hardness and impact resistance; PC / ABS (polycarbonate-acrylonitrile-butadiene-styrene copolymer) combines the advantages of both and is widely used in interior parts that require higher strength and toughness; PVC (polyvinyl chloride) is widely used in some soft interior parts such as seat armrests, interior panel coverings, etc. due to its good flexibility, flame retardancy and low cost; PP / EPDM (polypropylene- Ethylene propylene diene monomer rubber (EPDM) improves the weather resistance and flexibility of PP by adding EPDM rubber, and is used in automotive exterior decorative parts and interior parts used in some special environments; TPO (thermoplastic polyolefin) has certain applications in the surface coating of automotive interior parts due to its excellent weather resistance, chemical resistance and low-temperature flexibility; TPU (thermoplastic polyurethane) is used in some special functional parts of automotive interior parts, such as seat adjustment buttons, interior buckles, etc. due to its excellent wear resistance, elastic recovery and oil resistance.

[0004] In order to meet the increasingly diverse needs of customers, it has become an inevitable trend to paint different colors on automotive interior decoration parts. This requires the use of various paints to achieve the richness of colors. At present, the commonly used paints in the field of automotive interior decoration are alkyd, epoxy, amino paint and acrylic paint. Alkyd paint has good gloss, hardness and durability, and relatively low cost, but it dries slowly, has poor weather resistance, and is easy to fade when used outdoors; epoxy paint is widely used for its excellent adhesion, corrosion resistance and hardness, but has problems such as poor flexibility and long drying time; amino paint has good gloss, hardness, scratch resistance and chemical resistance, but usually requires high temperature baking and curing, and its application is limited on some heat-sensitive interior parts.

[0005] Acrylic paints are environmentally friendly, non-toxic, and non-flammable, which meet the environmental protection requirements of modern society for automotive interiors. They also have fast drying speed and are easy to apply, and have gradually become mainstream products in the coating of automotive interiors. However, existing acrylic paints have many problems. In terms of hardness, their values ​​are relatively low, which makes them easy to be scratched during daily use, affecting the aesthetics of automotive interiors; poor wear and scratch resistance means that the paint surface is easily worn and scratched when in contact with external objects, reducing the service life of the product; poor weather resistance means that the paint surface is prone to fading and powdering under natural environments such as long-term sunlight exposure and temperature changes; poor chemical resistance means that when exposed to some common chemicals such as gasoline, perfume, detergents, etc., the paint surface may undergo chemical reactions, resulting in wrinkling, discoloration, and even corrosion. During use, these problems combined can easily cause wrinkling, scratches, cracking and even falling off, which not only seriously affects the quality of automotive interior products, but also greatly shortens their service life, bringing users a bad experience, while also increasing the after-sales costs and maintenance difficulties of automakers. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides an acrylic resin for automobile interior and exterior plastic parts and a preparation method thereof. The acrylic resin has excellent hardness, wear resistance, scratch resistance, weather resistance, chemical resistance and the like, can improve the surface properties of the coating, increase adhesion, and can effectively prevent water vapor penetration.

[0007] The present invention is achieved through the following scheme: The present invention discloses an acrylic resin for automobile interior and exterior plastic parts, comprising the following raw materials in percentage by weight: Methacrylic acid 0.5wt%, methyl methacrylate 35-39wt%, butyl methacrylate 7-11wt%, hydroxyethyl methacrylate 13-17wt%, butyl acrylate 1-5wt%, glycidyl methacrylate 1-5wt%, trihydroxypropane triacrylate 0.5wt%, 2-ethylhexyl peroxide 0.5-1.5wt%, 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane 0.1-0.5wt%, butyl acetate 15-20wt%, propylene glycol methyl ether acetate 10-15wt%.

[0008] Preferably, the acrylic resin comprises the following raw materials in weight percentage: 0.5wt% methacrylic acid, 37wt% methyl methacrylate, 9wt% butyl methacrylate, 15wt% hydroxyethyl methacrylate, 3wt% butyl acrylate, 4wt% glycidyl methacrylate, 0.5wt% trihydroxypropane triacrylate, 0.6wt% 2-ethylhexyl peroxide, 0.4wt% 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane, 20wt% butyl acetate, and 10wt% propylene glycol methyl ether acetate.

[0009] In the present invention, the functions of each component are as follows: methacrylic acid: as a hard monomer, it improves the hardness and wear resistance of the coating; methyl methacrylate (MMA): as a hard monomer, it provides the hardness and gloss of the coating; butyl methacrylate: as a soft monomer, it increases the flexibility and adhesion of the coating; hydroxyethyl methacrylate (HEMA): as a functional monomer, it introduces hydroxyl groups to improve the crosslinking density and hardness of the coating; butyl acrylate: as a soft monomer, it improves the flexibility and chemical resistance of the coating; glycidyl methacrylate (GMA): as a functional monomer, it introduces epoxy groups, Improve the crosslinking density and chemical resistance of the coating; trihydroxypropane triacrylate: as a crosslinking monomer, improve the crosslinking density and hardness of the coating; 2-ethylhexyl peroxide: as an initiator, initiate the polymerization reaction of the monomer; 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane: as an initiator, synergistically acts with 2-ethylhexyl peroxide to control the speed and degree of the polymerization reaction; butyl acetate: as a solvent, adjust the viscosity of the coating, and promote the dissolution and mixing of the monomer; propylene glycol methyl ether acetate: as a solvent, adjust the viscosity of the coating, and promote the dissolution and mixing of the monomer.

[0010] In the present invention, the mechanism of interaction between the components is as follows: 1. The hardness of the coating can be controlled by adjusting the ratio of hard monomers (such as methacrylic acid and methyl methacrylate) and functional monomers (such as glycidyl methacrylate and trihydroxypropane triacrylate). The hard monomer provides the basic hardness of the coating, while the functional monomer increases the crosslinking density of the coating through crosslinking reaction, thereby improving the hardness; 2. The synergistic effect of hard monomers and functional monomers not only improves the hardness of the coating, but also enhances the wear and scratch resistance of the coating. The increase in cross-linking density makes the coating tougher and more resistant to external scratches and wear; Weather resistance: By selecting appropriate monomers and initiators, the light stability and weather resistance of the coating can be controlled. For example, the introduction of monomers such as methyl methacrylate and styrene can improve the weather resistance of the coating. 3. The introduction of functional monomers such as glycidyl methacrylate and trihydroxypropane triacrylate improves the chemical resistance of the coating through cross-linking reactions. These monomers form a cross-linked network in the coating, reducing the erosion of chemicals on the coating; 4. The introduction of soft monomers such as butyl methacrylate and butyl acrylate improves the adhesion of the coating to different substrates. These monomers increase the flexibility of the coating, allowing it to better adapt to the surface of the substrate, thereby improving adhesion; 5. By controlling the ratio of functional monomers and cross-linking monomers, a dense coating can be formed to effectively prevent water vapor penetration. The increase in cross-linking density makes the coating denser and reduces water vapor penetration.

[0011] The present invention also provides a method for preparing acrylic resin for automobile interior and exterior plastic parts, comprising the following steps: (1) 70%-75% of butyl acetate and propylene glycol methyl ether acetate are added to a reactor, stirred and mixed evenly, and the reactor is heated and then kept warm; this step is mainly to prepare the reaction medium and to create conditions for the subsequent polymerization reaction by heating and keeping warm.

[0012] (2) retaining 1‰ mass percentage of each of 2-ethylhexyl peroxide and 1,1-di-tert-butyl peroxide-3,5,5-trimethylcyclohexane, stirring and mixing the remaining components evenly, and then dripping them into the reactor; after the dripping is completed, flushing the dripping pipeline with butyl acetate and continuing to keep warm; in this step, 2-ethylhexyl peroxide and 1,1-di-tert-butyl peroxide-3,5,5-trimethylcyclohexane are used as initiators to initiate the polymerization reaction of acrylate monomers.

[0013] (3) half the weight percentage of the retained 2-ethylhexyl peroxide and 1,1-di-tert-butyl peroxide-3,5,5-trimethylcyclohexane and half of the remaining butyl acetate after flushing the dripping tube are mixed and stirred uniformly, added to the reaction kettle, and continued to keep warm; (4) mixing the remaining 2-ethylhexyl peroxide and 1,1-di-tert-butyl peroxide-3,5,5-trimethylcyclohexane with the remaining butyl acetate after rinsing the dropping tube, adding the mixture to the reaction kettle and continuing to keep warm; In the present invention, steps (3) and (4): adding the remaining initiator and butyl acetate mixture in two portions and continuing to keep warm. This step-by-step addition of the initiator helps control the speed and extent of the polymerization reaction, thereby obtaining the desired molecular weight and performance.

[0014] After the heat preservation is completed, the mixture is cooled to room temperature and filtered to obtain the acrylic resin for automobile interior and exterior plastic parts. This step is to allow the reaction to proceed completely and remove possible impurities by filtering to obtain the final acrylic resin product.

[0015] Through the above steps, acrylic resin suitable for automobile interior and exterior plastic parts can be prepared. The method of the present invention can obtain a product with excellent performance by accurately controlling the reaction conditions and the addition method of the initiator.

[0016] Furthermore, the temperature in step (1) is 125-130° C., and the temperature is kept constant until the dropwise addition of the mixed components in step (2) is completed.

[0017] Furthermore, the dripping time in step (2) is 4.0-5.0 hours, and the dripping speed is obtained by dividing the total mass wt% of the mixture components by the dripping time, and the dripping is controlled at a uniform speed.

[0018] Furthermore, the continued heat preservation in step (2) is heat preservation at 125-130° C. for 2.0-2.5 hours.

[0019] Furthermore, the continued heat preservation in step (3) is heat preservation at 125-130° C. for 2.0-2.5 hours.

[0020] Furthermore, the continued heat preservation in step (4) is heat preservation at 130-135° C. for 4.0-6.0 hours.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The acrylic resin for automobile interior and exterior plastic parts of the present invention can make the final resin have excellent hardness, wear resistance, scratch resistance, weather resistance, chemical resistance and other characteristics by controlling the dosage ratio of each component, can effectively improve the surface properties of the coating, increase adhesion, and can effectively prevent water vapor penetration.

[0022] (2) The raw materials used in the acrylic resin for automobile interior and exterior plastic parts of the present invention are all readily available products, the production process is simple, the cost is low, and it is suitable for large-scale industrial production.

[0023] (3) The acrylic resin for automobile interior and exterior plastic parts of the present invention has a water-white, clear and transparent appearance and a color (Fe-Co) ≤ 1 #, viscosity 2300-3400cps / 25℃, solid content 70±2%, acid value <5mgKOH / g, hydroxyl value 92mgKOH / g. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present application more clear, the present invention is further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments. It should be pointed out that if there are processes or parameters that are not particularly described in detail below, they can be understood or implemented by those skilled in the art with reference to the prior art. Example

[0025] An acrylic resin for automobile interior and exterior plastic parts, the weight component raw materials of which include: Monomers: 0.5Kg methacrylic acid, 37Kg methyl methacrylate, 9Kg butyl methacrylate, 15Kg hydroxyethyl methacrylate, 3Kg butyl acrylate, 4Kg glycidyl methacrylate, 0.5Kg trihydroxypropane triacrylate; Initiator: 0.6 kg of 2-ethylhexyl peroxide and 0.4 kg of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane; Solvent: 20Kg of butyl acetate, 10Kg of propylene glycol methyl ether acetate; The preparation of the acrylic resin for automobile interior and exterior plastic parts comprises the following steps: (1) 15 kg of butyl acetate and 10 kg of propylene glycol methyl ether acetate were added to a reaction kettle, stirred and mixed evenly, and the temperature of the reaction kettle was raised to 128° C. and maintained at this temperature until the dropwise addition of the mixed components in step (2) was completed; (2) retaining 0.6 g of 2-ethylhexyl peroxide and 0.4 g of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane, and stirring the monomers consisting of methacrylic acid, methyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, butyl acrylate, glycidyl methacrylate, and trihydroxypropane triacrylate, and the remaining initiators 2-ethylhexyl peroxide and 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane to uniformly mix to obtain a mixed solution; (3) The mixed solution was uniformly added dropwise to the reaction kettle at a flow rate of V = 0.26 kg / min. After the addition was completed, the addition line was rinsed with butyl acetate and the temperature was kept at 128 ° C for 2.0 hours; (4) adding 0.3 g of 2-ethylhexyl peroxide and 0.2 g of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane and the remaining 2.5 kg of butyl acetate after flushing the dripping tube to the reaction kettle, and keeping the temperature at 130° C. for 2.0 hours; (5) 0.3 g of 2-ethylhexyl peroxide and 0.2 g of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane and the remaining 2.5 kg of butyl acetate solution for flushing the dripping tube were added to the reactor again, and the mixture was kept at 135° C. for 5.0 hours; (5) After the heat preservation is completed, the mixture is cooled to room temperature and filtered to obtain the acrylic resin for automobile interior and exterior plastic parts.

[0026] (6) The appearance of the obtained acrylic resin for automobile interior and exterior plastic parts is water white, clear and transparent, and the color (Fe-Co) is ≤1 # , viscosity 3050cps / 25℃, solid content 70.2%, acid value 2.86mgKOH / g, hydroxyl value 92mgKOH / g. Example

[0027] An acrylic resin for automobile interior and exterior plastic parts, the weight component raw materials of which include: Monomers: 5Kg of methacrylic acid, 360Kg of methyl methacrylate, 80Kg of butyl methacrylate, 160Kg of hydroxyethyl methacrylate, 35Kg of butyl acrylate, 45Kg of glycidyl methacrylate, 5Kg of trihydroxypropane triacrylate; Initiator: 4 kg of 2-ethylhexyl peroxide, 6 kg of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane; Solvent: 220Kg of butyl acetate, 80Kg of propylene glycol methyl ether acetate; The preparation of the acrylic resin for automobile interior and exterior plastic parts comprises the following steps: (1) 170 kg of butyl acetate and 80 kg of propylene glycol methyl ether acetate were added to a reaction kettle, stirred and mixed evenly, and the temperature of the reaction kettle was raised to 128° C., and the temperature was maintained until the dropwise addition of the mixed components in step (2) was completed; (2) retaining 4 g of 2-ethylhexyl peroxide and 6 g of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane, and stirring the monomers consisting of methacrylic acid, methyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, butyl acrylate, glycidyl methacrylate, and trihydroxypropane triacrylate, and the remaining initiators 2-ethylhexyl peroxide and 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane to uniformly mix to obtain a mixed solution; (3) The mixed solution was uniformly added dropwise to the reaction kettle at a flow rate of V = 2.33 kg / min. After the addition was completed, the addition line was rinsed with butyl acetate and the temperature was kept at 128°C for 2.0 hours; (4) adding 3 g of 2-ethylhexyl peroxide and 2 g of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane and the remaining 25 kg of butyl acetate after flushing the dripping tube to the reaction kettle, and keeping the temperature at 130° C. for 2.0 hours; (5) 3 g of 2-ethylhexyl peroxide and 2 g of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane and the remaining 25 kg of butyl acetate solution for flushing the dripping tube were added to the reactor again and kept at 135° C. for 5.0 hours; (5) After the heat preservation is completed, the mixture is cooled to room temperature and filtered to obtain the acrylic resin for automobile interior and exterior plastic parts.

[0028] (6) The appearance of the obtained acrylic resin for automobile interior and exterior plastic parts is water white, clear and transparent, and the color (Fe-Co) is ≤1 # , viscosity 3350cps / 25℃, solid content 69.8%, acid value 2.44mgKOH / g, hydroxyl value 105mgKOH / g. Example

[0029] An acrylic resin for automobile interior and exterior plastic parts, the weight component raw materials of which include: Monomers: 5Kg of methacrylic acid, 380Kg of methyl methacrylate, 100Kg of butyl methacrylate, 150Kg of hydroxyethyl methacrylate, 30Kg of butyl acrylate, 20Kg of glycidyl methacrylate, 5Kg of trihydroxypropane triacrylate; Initiator: 8 kg of 2-ethylhexyl peroxide, 2 kg of 1,1-di-tert-butyl peroxide-3,5,5-trimethylcyclohexane; Solvent: 150Kg of butyl acetate, 150Kg of propylene glycol methyl ether acetate; The preparation of the acrylic resin for automobile interior and exterior plastic parts comprises the following steps: (1) 100 kg of butyl acetate and 150 kg of propylene glycol methyl ether acetate were added to a reaction kettle, stirred and mixed evenly, and the temperature of the reaction kettle was raised to 128° C., and the temperature was maintained until the dropwise addition of the mixed components in step (2) was completed; (2) retaining 4 g of 2-ethylhexyl peroxide and 6 g of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane, and stirring the monomers consisting of methacrylic acid, methyl methacrylate, butyl methacrylate, hydroxyethyl methacrylate, butyl acrylate, glycidyl methacrylate, and trihydroxypropane triacrylate, and the remaining initiators 2-ethylhexyl peroxide and 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane to uniformly mix to obtain a mixed solution; (3) The mixed solution was uniformly added dropwise to the reaction kettle at a flow rate of V = 2.33 kg / min. After the addition was completed, the addition line was rinsed with butyl acetate and the temperature was kept at 128°C for 2.0 hours; (4) adding 3 g of 2-ethylhexyl peroxide and 2 g of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane and the remaining 25 kg of butyl acetate after flushing the dripping tube to the reaction kettle, and keeping the temperature at 130° C. for 2.0 hours; (5) 3 g of 2-ethylhexyl peroxide and 2 g of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane and the remaining 25 kg of butyl acetate solution for flushing the dripping tube were added to the reactor again and kept at 135° C. for 5.0 hours; (5) After the heat preservation is completed, the mixture is cooled to room temperature and filtered to obtain the acrylic resin for automobile interior and exterior plastic parts.

[0030] (6) The appearance of the obtained acrylic resin for automobile interior and exterior plastic parts is water white, clear and transparent, and the color (Fe-Co) is ≤1 # , viscosity 2380cps / 25℃, solid content 69.9%, acid value 2.57mgKOH / g, hydroxyl value 94mgKOH / g.

[0031] An acrylic resin for automobile interior and exterior plastic parts, wherein the raw materials of each weight component in Example 3 are replaced by the following: Monomers: 5Kg methacrylic acid, 420Kg methyl methacrylate, 110 Kg butyl acrylate, 150Kg hydroxyethyl acrylate, 20Kg glycidyl methacrylate, 5Kg trihydroxypropane triacrylate; Initiator: 5 kg of 2-ethylhexyl peroxide, 2 kg of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane; Solvent: 170Kg of butyl acetate, 130Kg of propylene glycol methyl ether acetate; The remaining steps are the same as in Example 3.

[0032] The obtained acrylic resin for automobile interior and exterior plastic parts has a water-white, clear and transparent appearance, and the color (Fe-Co) is ≤1 # , viscosity 6680cps / 25℃, solid content 68.9%, acid value 2.57mgKOH / g, hydroxyl value 102mgKOH / g.

[0033] An acrylic resin for automobile interior and exterior plastic parts, wherein the raw materials of each weight component in Example 3 are replaced by the following: Monomers: 5Kg of methacrylic acid, 390Kg of methyl methacrylate, 90Kg of isobutyl methacrylate, 160Kg of hydroxyethyl methacrylate, 30Kg of 2-ethylhexyl acrylate, 20Kg of glycidyl methacrylate, 5Kg of trihydroxypropane triacrylate; Initiator: 10 kg of 2-ethylhexyl peroxide, 3 kg of 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane; Solvent: 200Kg of butyl acetate, 100Kg of propylene glycol methyl ether acetate; The remaining steps are the same as in Example 3.

[0034] The obtained acrylic resin for automobile interior and exterior plastic parts has a water-white, clear and transparent appearance, and the color (Fe-Co) is ≤1 # , viscosity 10150cps / 25℃, solid content 69.1%, acid value 2.57mgKOH / g, hydroxyl value 99mgKOH / g.

[0035] An acrylic resin for automobile interior and exterior plastic parts, wherein the raw materials of each weight component in Example 3 are replaced by the following: Monomers: 5Kg of methacrylic acid, 370Kg of methyl methacrylate, 90Kg of butyl methacrylate, 170Kg of hydroxypropyl methacrylate, 40Kg of isobutyl acrylate, 20Kg of glycidyl methacrylate, 5Kg of trihydroxypropane triacrylate; Initiator: 7 kg of 2-ethylhexyl peroxide, 3 kg of 1,1-di-tert-butyl peroxide-3,5,5-trimethylcyclohexane; Solvent: 200Kg of butyl acetate, 100Kg of propylene glycol methyl ether acetate; The remaining steps are the same as in Example 3.

[0036] The obtained acrylic resin for automobile interior and exterior plastic parts has a water-white, clear and transparent appearance, and the color (Fe-Co) is ≤1 # , viscosity 8850cps / 25℃, solid content 68.8%, acid value 2.80mgKOH / g, hydroxyl value 95mgKOH / g.

[0037] An acrylic resin for automobile interior and exterior plastic parts, wherein the raw materials of each weight component in Example 3 are replaced by the following: Monomers: 5Kg of methacrylic acid, 360Kg of methyl methacrylate, 100Kg of butyl methacrylate, 180Kg of hydroxybutyl methacrylate, 30Kg of butyl acrylate, 20Kg of glycidyl tert-butyl carbonate, 5Kg of trihydroxypropane triacrylate; Initiator: 2-ethylhexyl peroxide 12Kg, 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane 6Kg; Solvent: 200Kg of butyl acetate, 100Kg of propylene glycol methyl ether acetate; The remaining steps are the same as in Example 3.

[0038] The obtained acrylic resin for automobile interior and exterior plastic parts has a water-white, clear and transparent appearance, and the color (Fe-Co) is ≤1 # , viscosity 1850cps / 25℃, solid content 69.8%, acid value 1.58 mgKOH / g, hydroxyl value 94mgKOH / g.

[0039] Performance evaluation of acrylic resin for automotive interior and exterior plastic parts The resins prepared in Examples 1-3 and Comparative Examples 1-4 of the present invention were mixed with fumed silica, polyurea resin, leveling agent, substrate wetting agent, feel aid, HT100 curing agent, and diluent, and stirred evenly. Then, according to the national standard "GB / T1727 General Preparation Method for Paint Film", the coatings prepared in Examples 1-3 and Comparative Examples 1-4 were sprayed on the automotive interior substrate, dried at 80°C for 30 minutes, and cooled to obtain paint films. The performance results of the paint films obtained by testing are shown in Table 1.

[0040] Adhesion: Use a utility knife to scratch the sample directly to the substrate, with a 3mm interval between the horizontal and vertical scratches. Stick 3M tape on the scratched area, press the tape tightly for 90 seconds, and then tear off the tape instantly in a 180-degree direction as much as possible. The percentage of the area where the coating does not fall off to the total area is expressed; Pencil hardness: Tested according to GB6739-2006; Water boiling resistance test: After boiling at 80℃ for 120h, use 3M tape to test the adhesion of 100 grids, with 0 being the best and 5 being the worst; Adhesion test after humidity and heat resistance: After being placed at 40℃ and 90%RH for 240h, the adhesion is tested by 100 grids with 3M adhesive tape; Corrosion resistance test: refer to GB / T10125-1997 for testing, and then evaluate the corrosion results according to the provisions of GB12335-90 (expressed as the percentage of the corrosion area after 30 days to the total area). The smaller the corrosion area, the better; Weather resistance test: Refer to GB / T1767-79 (89) for testing, and then evaluate according to the weather resistance grade. The lower the ΔE yellowing value, the better the weather resistance; Wear resistance test: Tested according to SAE J948, 500g load, CS-10 grinding wheel, 200 cycles, wear occurs; Anti-scratch test: Test according to SAEJ948, 250g load, CS-0 grinding wheel, 500 cycles, observe whether the texture is damaged; Acid and alkali resistance test: Test according to GB / T9274-1988, immerse the sample in 5% sulfuric acid or 5% sodium hydroxide solution, take it out after 24 hours, and evaluate the coating changes; Table 1

[0041] As shown in Table 1, the coating films of acrylic resin for automobile interior and exterior plastic parts of Examples 1-3 of the present invention have high adhesion, high hardness, high gloss, high heat resistance, good wear resistance and scratch resistance, and good corrosion resistance. In Comparative Example 1, the soft segment butyl acrylate and hydroxyethyl acrylate monomers were replaced, and the hardness and scratch resistance of the prepared coating film were significantly reduced; in Comparative Example 2 and Comparative Example 3, the addition of isomers with a higher degree of branching, isobutyl methacrylate / isobutyl acrylate, significantly increased the overall glass transition temperature, and the hardness of the prepared coating film was too high, the paint film was brittle, and the substrate adhesion was reduced; in Comparative Example 4, long carbon chain hydroxybutyl methacrylate and tert-butyl glycidyl carbonate were added, and the prepared coating film had reduced scratch resistance and wear resistance. The relative reactivity of the long chain segment structure monomers hydroxybutyl methacrylate and tert-butyl glycidyl carbonate was different, resulting in different conversion rates of each monomer, and a large difference in the long carbon chain structure, which in turn led to performance differences.

[0042] Specifically, in the formulations of Examples 1 to 3, the presence of soft monomers such as butyl methacrylate and butyl acrylate provides flexibility to the coating film. This flexibility enables the coating film to better fit the surface microstructure of the plastic part, reduce stress concentration, and thus improve adhesion. The functional groups (epoxy groups) introduced by functional monomers such as glycidyl methacrylate can react with the active groups on the surface of the plastic part or form hydrogen bonds and other interactions, further enhancing the connection between the coating film and the substrate, which helps to improve adhesion.

[0043] At the same time, hard monomers such as methyl methacrylate form a rigid structure after polymerization, which increases the hardness of the coating. At the same time, trihydroxypropane triacrylate, as a cross-linking monomer, forms a cross-linked network structure during the polymerization process, making the connection between the molecules of the coating film tighter, restricting the movement of the molecular chain, thereby increasing the hardness.

[0044] In addition, hard monomers such as methyl methacrylate help to form a smoother surface structure. When light hits the surface of the coating, due to the high surface flatness, the light can be reflected regularly, resulting in a higher gloss. The appropriate monomer ratio and polymerization reaction conditions make the internal structure of the coating uniform without obvious defects or pores, which also helps to improve the gloss.

[0045] Moreover, the presence of hard monomers (such as methyl methacrylate) and cross-linking monomers increases the thermal stability of the coating. In high temperature environments, these rigid structures can resist the effects of heat, reduce the thermal motion and deformation of the molecular chains, and thus maintain the performance of the coating. The cross-linking between the functional monomers and other monomers also helps to improve the overall structural stability of the coating, making it less likely to soften and deform at higher temperatures.

[0046] Furthermore, the high hardness and tight cross-linked network structure enable the coating to resist friction and scratches from external objects, showing good wear and scratch resistance. Functional monomers (such as glycidyl methacrylate) increase the cross-linking density of the coating, making it difficult for external chemicals (such as acids, alkalis, salts and other corrosive substances) to penetrate into the coating, thereby improving corrosion resistance.

[0047] In the formula of Comparative Example 1, when the butyl acrylate and hydroxyethyl acrylate monomers of the soft segment are replaced, the balance between the monomers in the original formula may be destroyed. The new monomers may not provide sufficient flexibility to adapt to the surface of the plastic part, resulting in a loose bond between the coating and the substrate. This loose bond and the different physical and chemical properties that the new monomers may have make the coating more susceptible to deformation and damage when subjected to external forces, resulting in a significant decrease in hardness and scratch resistance.

[0048] In the formulas of Comparative Examples 2 and 3, the overall glass transition temperature is significantly increased, the hardness is too high, the paint film is brittle, and the adhesion to the substrate is reduced. After adding the isomers of isobutyl methacrylate / isobutyl acrylate with a higher degree of branching, the polymerization reaction mode between the monomers may change due to the particularity of their molecular structure. These branched monomers may increase the degree of entanglement between the molecular chains, causing the glass transition temperature of the coating to increase. The increase in the glass transition temperature means that the coating will only change from a glassy state to a highly elastic state at a higher temperature, and will be more rigid at room temperature. Excessive hardness makes the paint film lack flexibility and prone to brittle fracture. At the same time, since the structure of the branched monomer is quite different from the monomer structure in the original formula, it may affect the interaction between the coating and the substrate, resulting in a decrease in substrate adhesion.

[0049] In the formula of Comparative Example 4, after adding long carbon chain hydroxybutyl methacrylate and tert-butyl glycidyl carbonate, the conversion rate of each monomer is different due to the different relative reactivity of the long carbon chain structure monomers. During the polymerization process, the long carbon chain structure produces a large difference, making the structure inside the coating film uneven. This unevenness will become a stress concentration point when the coating film is rubbed or scratched, which can easily cause the coating film to be damaged at these locations, resulting in a decrease in scratch resistance and wear resistance.

[0050] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An acrylic resin for automobile interior and exterior plastic parts, characterized in that: The following raw materials are included in weight percentage: Methacrylic acid 0.5wt% Methyl methacrylate 35-39wt% Butyl methacrylate 7-11wt% Hydroxyethyl methacrylate 13-17wt% Butyl acrylate 1-5wt% Glycidyl methacrylate 1-5wt% Trihydroxypropane triacrylate 0.5wt% 2-Ethylhexyl peroxide 0.5-1.5wt% 1,1-di-tert-butylperoxy-3,5,5-trimethylcyclohexane 0.1-0.5wt% Butyl acetate 15-20wt% Propylene glycol methyl ether acetate 10-15wt%.

2. The acrylic resin for automobile interior and exterior plastic parts according to claim 1, characterized in that: The following raw materials are included in weight percentage: Methacrylic acid 0.5wt% Methyl methacrylate 37wt% Butyl methacrylate 9 wt% Hydroxyethyl methacrylate 15wt% Butyl acrylate 3 wt% Glycidyl methacrylate 4wt% Trihydroxypropane triacrylate 0.5wt% 2-Ethylhexyl peroxide 0.6wt% 1,1-di-tert-butylperoxy-3,5,5-trimethylcyclohexane 0.4wt% Butyl acetate 20wt% Propylene glycol methyl ether acetate 10wt%.

3. The method for preparing an acrylic resin for automobile interior and exterior plastic parts according to claim 1 or 2, characterized in that: The steps include: (1) adding 70% to 75% of butyl acetate and propylene glycol methyl ether acetate into a reaction kettle, stirring and mixing them evenly, and then heating the reaction kettle and then keeping it warm; (2) Retain 1‰ mass percent of 2-ethylhexyl peroxide and 1,1-di-tert-butyl peroxide-3,5,5-trimethylcyclohexane, stir and mix the remaining components, and then add them dropwise to the reactor; after the addition is completed, rinse the addition pipeline with butyl acetate and continue to keep warm; (3) half the weight percentage of the retained 2-ethylhexyl peroxide and 1,1-di-tert-butyl peroxide-3,5,5-trimethylcyclohexane and half of the remaining butyl acetate after flushing the dripping tube are mixed and stirred uniformly, added to the reaction kettle, and continued to keep warm; (4) again mixing the remaining percentage of 2-ethylhexyl peroxide and 1,1-di-tert-butylperoxide-3,5,5-trimethylcyclohexane with the remaining butyl acetate after rinsing the dripping tube, adding them to the reaction kettle and continuing to keep warm; (5) After the heat preservation is completed, the mixture is cooled to room temperature and filtered to obtain the acrylic resin for automobile interior and exterior plastic parts.

4. The method for preparing an acrylic resin for automobile interior and exterior plastic parts according to claim 3, characterized in that: The temperature in step (1) is 125-130° C., and the temperature is maintained until the mixed components in step (2) are added dropwise.

5. The method for preparing an acrylic resin for automobile interior and exterior plastic parts according to claim 3, characterized in that: The dropping time in step (2) is 4.0-5.0 hours, and the dropping speed is obtained by dividing the total mass of the mixture components by the dropping time, and the dropping is controlled at a uniform speed.

6. The method for preparing an acrylic resin for automobile interior and exterior plastic parts according to claim 3, characterized in that: The continued heat preservation in step (2) is to keep the temperature at 125-130° C. for 2.0-2.5 hours.

7. The method for preparing an acrylic resin for automobile interior and exterior plastic parts according to claim 3, characterized in that: The continued heat preservation in step (3) is to keep the temperature at 125-130° C. for 2.0-2.5 hours.

8. The method for preparing an acrylic resin for automobile interior and exterior plastic parts according to claim 3, characterized in that: The continued heat preservation in step (4) is heat preservation at 130-135°C for 4.0-6.0 hours.

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