A method for recycling PET to make molded resin and colorful pearl button

Abstract

The application provides a preparation method of a PET recycling molded resin and a colorful pearl button, and the colorful pearl button is made of the PET recycling molded resin. The preparation method adopts specific process steps, conditions and parameters, realizes good interaction as a whole, and the product shape is more full. In addition to being able to meet the functional requirements of the button when used in clothing accessories, such as water washing color fastness, dry cleaning color fastness, machine washing color fastness and the like, the button can also meet the requirements of high temperature aging test and test in a high temperature and high humidity environment, has a broad market prospect, leads the future development and direction of the button industry, and the like. Meanwhile, the preparation method provided by the application is simple in process technology operation, reduces the experience dependence on technical personnel, is suitable for large-scale and small-scale operations, effectively reduces the product defective rate, improves the production efficiency, and reduces the raw material waste and labor cost.

Description

Technical Field

[0001] This invention relates to the field of garment accessories and crafts technology, such as resin buttons, and more specifically, to a method for preparing molding resin and colorful pearlescent buttons by recycling PET. Background Technology

[0002] PET plastic bottles are among the most common types of plastic bottles used for packaging beverages and liquid products. With increasing attention to environmental protection and sustainability, the market prospects for PET plastic bottles are very promising. Firstly, PET plastic bottles are recyclable, making them more environmentally friendly than other plastic bottles. As more countries and companies implement plastic recycling programs, the demand for PET plastic bottles will continue to increase. Secondly, PET plastic bottles can be recycled and reused, which helps reduce environmental impact. With improvements in PET recycling technology and reduced costs, the recycling rate of PET beverage bottles is also constantly increasing. Furthermore, with increasing focus on health and wellness, PET beverage bottles are also being used to package health products and pharmaceuticals. This will further increase the demand for PET beverage bottles. However, the recycling and reuse of PET plastic bottles also faces some challenges.

[0003] So how are PET plastic bottles recycled? There are currently many methods to achieve the recycling of PET plastic bottles. PET polyester waste and scraps generated during production and processing are relatively clean and can be directly recycled using physical methods. This involves washing, crushing, purifying, or modifying the waste to prepare recycled granules, which can then be used for polycondensation, thickening, and recycling. Another part comes from waste PET polyester bottles, polyester films, etc. This part of the waste PET material is mainly reused after being degraded by chemical methods. This involves separation, purification, melting, and depolymerization to break down the waste PET into monomeric small molecules, such as terephthalic acid (TPA), dimethyl terephthalate (DMT), ethylene glycol terephthalate (BHET), ethylene glycol (EG), dioctyl terephthalate (DOTP), sodium hydrogen terephthalate (PHT), etc. These monomeric small molecules can be used as raw materials for synthesizing polyester or to make other products, such as unsaturated polyester, adhesives, alkyd paints, insulating paints, powder coatings, etc., thereby realizing the recycling of waste PET polyester plastics.

[0004] As the world's largest plastic recycling company, Wellman Industries, Inc. of the United States was the first to see the potential market for PET waste recycling. By processing PET polyester waste into usable flakes or pellets, they established the first recycling chain for polyester packaging and fiber regeneration. In 1993, they launched the first polyester textile fiber made from waste polyester (Fortrel EcoSpun), which can be used in clothing, home décor, woven and knitted backpacks and blankets, T-shirts, sportswear, soft bags, and socks. Recently, Toray Industries of Japan announced the development of a new commercial fiber called "&+", the successful development of which will open up new possibilities for Toray in the production of commercial fibers from waste PET plastic bottles. In May 2022, Toray Industries and Axens announced a collaboration to build a new PET chemical recycling plant. The new plant will utilize Axens' Rewind PET technology, combined with Toray's polymerization equipment, and will be able to recycle 80,000 tons of PET plastic waste annually upon completion. With the innovation and upgrading of PET recycling technology in recent years, the application fields of recycled PET polyester plastic bottles have become more extensive. For example, recycled PET can be processed into fibers in spinning equipment. Its filaments and staple fibers are widely used in the clothing fabric field, which is currently the most widely used field. It can also be used in various fields such as electronics, printing, packaging, films, instrument panels, and capacitor insulation.

[0005] Currently, existing technologies have the following drawbacks: 1. Conventional PET resins have low activity, making them suitable only for centrifugal molding, casting, or drip molding. Furthermore, their heat distortion temperature is low, making them unsuitable for high-temperature compression molding and the creation of iridescent pearlescent button effects. 2. Conventional PET resins have too high viscosity, resulting in excessive fluidity during high-temperature compression molding, preventing the resin from filling the mold cavity. Increased viscosity is needed to reduce this. 3. Button effects and shapes are limited, typically limited to ordinary pearlescent buttons. Only standard round shapes can be produced, not irregular shapes like Baroque. In short, the technology for manufacturing buttons using conventional PET resin for compression molding is not yet mature. The technology for using recycled PET to create iridescent pearlescent buttons remains a gap both domestically and internationally. Summary of the Invention

[0006] In view of this, the purpose of this invention is to: improve the reactivity of PET resin by introducing maleic anhydride and acetic anhydride as activators during the conventional PET resin synthesis process, thereby obtaining a PET recycling resin suitable for high-temperature molding. Since maleic anhydride and acetic anhydride, as activators, can rapidly react with the hydroxyl groups in polyester resin to form ester bonds, they can significantly improve the crosslinking reactivity of the polyester resin. The introduction of maleic anhydride and acetic anhydride can increase the crosslinking density and heat distortion temperature of the resin, significantly improving its heat resistance, thus making it more suitable for high-temperature molding. Simultaneously, a thickener is added during the resin polymerization stage to adjust the resin viscosity. The application of the thickener can meet the required resin viscosity, and the thickened preform can quickly fill the mold cavity at the molding temperature, resulting in a more vibrant pearlescent effect and fuller shape. Finally, addressing the relatively simple effect and shape of buttons, this invention combines mold design and improvement, such as the design and development of Baroque irregular shapes, to enhance their artistry, decoration, and aesthetics beyond their original function, creating core competitiveness for the company's new products and technologies, and continuing to lead the future development and direction of the button industry.

[0007] This invention provides a method for preparing molding resin and colorful pearlescent buttons by recycling PET, comprising the following steps:

[0008] S1) The recycled PET particles are put into a reactor containing an alcoholysis agent and a catalyst for depolymerization. The stirrer is turned on and the reactor is heated to carry out an alcoholysis melting reaction to obtain the alcoholysis product.

[0009] S2) Using the alcoholysis product obtained in S1, add unsaturated diacid, activator and diol, stir and reflux at 155℃~165℃, control the steam temperature at 80℃~110℃, then gradually raise the temperature to 220℃~250℃, and continue to react under vacuum for 1h~2h. Stop heating when the acid value of the system reaches 40mgKOH / g~60mgKOH / g. When the system temperature drops below 100℃, start to add diluent and polymerization inhibitor, mix evenly under nitrogen atmosphere and mechanical stirring to obtain a liquid resin suitable for compression molding for PET recycling;

[0010] S3) Add a thickener to the liquid resin obtained above and mix thoroughly. At the same time, add a curing agent and thicken and prepolymerize at a certain temperature. After a period of time, a prepolymerized mixed slurry can be obtained.

[0011] S4) Add color paste and iridescent pearl to the prepolymerized slurry obtained above, and mold it at a certain temperature and pressure to obtain a blank with iridescent pearl effect. After the blank is stamped, cut and polished, iridescent pearl buttons made of recycled PET molding resin can be obtained.

[0012] The present invention first puts the recycled PET particles into a reactor containing an alcoholysis agent and a catalyst for depolymerization, turns on the stirrer and heats the reactor to carry out an alcoholysis melting reaction to obtain the alcoholysis product.

[0013] In this invention, the alcoholysis agent is preferably a mixture of neopentyl glycol and diethylene glycol, and the preferred mass ratio of the two is neopentyl glycol: diethylene glycol = (15:1) to (5:1).

[0014] In this invention, the catalyst is preferably a mixture of MX and NX;

[0015] Specifically, M is preferably Zn. 2+ Mn 2+ Mg 2+ Co 2+ Sb 2+ Cu 2+ Sn 2+ One or more of the following, N is preferred. A mixture of one or more of them, wherein X is preferably Cl - WO4 2- H2PO4 - AlCl4 - ,RAcO - R is preferably one or more of CH3, C2H5, C3H8, and C6H5; R1 is preferably one or more of CH3, C2H5, C3H8, and C6H5; R2 is preferably one or more of CH3, C2H5, C3H8, and C6H5; R3 is preferably one or more of CH3, C2H5, C3H8, and C6H5; and R4 is preferably one or more of CH3, C2H5, C3H8, and C6H5.

[0016] In this invention, the catalyst is preferably a mixture of MX and NX, wherein the mass ratio of MX to NX is preferably (3:1) to (6:1).

[0017] The present invention does not impose any special restrictions on the source of the PET recycled particles, alcoholysis agent, and catalyst, and commercially available products or self-made products well known to those skilled in the art can be used.

[0018] In this invention, the preferred mass ratio of the PET recycled particles to the alcoholysis agent and the catalyst is: PET recycled particles: alcoholysis agent: catalyst = (25%~32%): (20%~30%): (0.2%~0.4%).

[0019] In this invention, the heating temperature is preferably 220℃~250℃, and the alcoholysis time is preferably 60min~90min.

[0020] Then, the present invention uses the alcoholysis product obtained in the above steps, adds unsaturated diacid, activator and diol, stirs and refluxes the reaction at 155℃~165℃, controls the steam temperature at 80℃~110℃, then gradually raises the temperature to 220℃~250℃, and continues to react under vacuum for 1h~2h, and stops heating when the acid value of the system reaches 40mgKOH / g~60mgKOH / g. After the system temperature drops below 100℃, diluent and polymerization inhibitor are added, and the mixture is mixed evenly under nitrogen atmosphere and mechanical stirring to obtain a liquid resin suitable for compression molding for PET recycling.

[0021] In this invention, the unsaturated dicarboxylic acid is preferably one or a mixture of several of isophthalic acid, maleic acid, fumaric acid, and itaconic acid; the activator is preferably maleic anhydride and acetic anhydride; the diol is preferably one or a mixture of several of ethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and butanediol; wherein the preferred ratio between the components is: 20-30 parts by weight of unsaturated dicarboxylic acid: 5-15 parts by weight of maleic anhydride: 5-15 parts by weight of acetic anhydride: 60-80 parts by weight of diol.

[0022] The present invention does not impose any special restrictions on the source of the unsaturated dicarboxylic acid, maleic anhydride, acetic anhydride and diol, and commercially available products or homemade products well known to those skilled in the art can be used.

[0023] In this invention, the preferred ratio between the diluent and the polymerization inhibitor is (15-25 parts by weight): (0.04-0.06 parts by weight); the diluent is preferably one or more of styrene, HEA, HPA, HEMA, HPMA, MMA, dimethacrylate, and butyl acrylate; the polymerization inhibitor is preferably one or more of 1,4-hydroquinone, tert-butylhydroquinone (TBHQ), 2,5-di-tert-butylhydroquinone, 1,4-benzoquinone, and methylhydroquinone (THQ).

[0024] The present invention does not impose any special restrictions on the source of the diluent and the polymerization inhibitor; commercially available products or homemade products well known to those skilled in the art can be used.

[0025] Subsequently, the present invention adds a thickener to the liquid resin obtained above and mixes it thoroughly, while adding a curing agent, and performs thickening and prepolymerization at a certain temperature. After a period of time, a prepolymerized mixed slurry can be obtained.

[0026] In this invention, the curing agent is preferably one or more of methyl ethyl ketone peroxide, cyclohexanone peroxide, and benzoyl peroxide, and the specific gravity of the curing agent is preferably 0.6 to 2.0 parts by weight; the thickener is preferably one or a mixture of several of starch, sodium alginate, β-cyclodextrin, polysaccharide derivatives, carboxymethyl cellulose, sodium proteate, and casein, and the specific gravity of the thickener is preferably 3.0 to 6.0 parts by weight.

[0027] The present invention does not impose any special restrictions on the source of the curing agent and thickener, and commercially available products or homemade products well known to those skilled in the art can be used.

[0028] Finally, the present invention adds color paste and iridescent pearl to the prepolymerized mixed slurry obtained above, and molds it at a certain temperature and pressure to obtain a blank with iridescent pearl effect through high temperature molding. The blank obtained above is then subjected to button making and polishing processes such as stamping and cutting to obtain iridescent pearl buttons made of PET recycled molding resin.

[0029] In this invention, the specific gravity of the color paste is preferably 0.1 to 2 parts by weight, the specific gravity of the multicolored pearlescent pigment is preferably 0.5 to 2 parts by weight, the molding temperature is preferably 120°C to 140°C, the molding pressure is preferably 10 MPa to 15 MPa, and the molding time is preferably 120 s to 300 s.

[0030] The present invention does not impose any special restrictions on the source of the pigments and iridescent pearlescent materials; commercially available products or homemade products well known to those skilled in the art can be used.

[0031] This invention provides a method for preparing molding resin and colorful pearlescent buttons by recycling PET, comprising the following steps: S1) feeding recycled PET particles into a reactor containing an alcoholysis agent and a catalyst for depolymerization, turning on the stirrer and heating to carry out an alcoholysis melting reaction to obtain alcoholysis product; S2) using the alcoholysis product obtained in S1, adding an unsaturated diacid, an activator, and a diol, stirring and refluxing the reaction at 155℃~165℃, controlling the steam temperature at 80℃~110℃, then gradually raising the temperature to 220℃~250℃, and continuously reacting under vacuum for 1h~2h, stopping heating when the acid value of the system reaches 40mgKOH / g~60mgKOH / g, and waiting for the system temperature to drop to Below 100℃, diluent and polymerization inhibitor are added, and the mixture is stirred evenly under a nitrogen atmosphere and mechanical stirring to obtain a liquid resin suitable for molding from recycled PET; S3) Thickener is added to the liquid resin obtained above and mixed thoroughly, and curing agent is added at the same time. Thickening and prepolymerization are carried out at a certain temperature, and a prepolymerized mixed slurry is obtained after a period of time; S4) Color paste and iridescent pearl are added to the prepolymerized mixed slurry obtained above, and a blank with iridescent pearl effect is obtained by high-temperature molding under a certain temperature and pressure. The blank obtained above is then processed by stamping, cutting and other button-making and polishing processes to obtain iridescent pearl buttons made from recycled PET molding resin. Compared with existing technologies, the preparation method provided by this invention adopts specific process steps, conditions and parameters to achieve better overall interaction, resulting in a more complete product shape. In addition to meeting the functional requirements that buttons must have when used in clothing accessories, such as color fastness to washing, dry cleaning and machine washing, it can also meet the requirements of high temperature aging test and high temperature and humidity environment test. It has broad market prospects, builds the core competitiveness of the company's new products and new technologies, and leads the future development and direction of the button industry.

[0032] Meanwhile, the preparation method provided by this invention has a simple process and reduces the dependence on the experience of technical personnel. It is suitable for both large-scale and small-scale operations. It also effectively reduces the product defect rate, improves production efficiency, and reduces raw material waste and labor costs. Attached Figure Description

[0033] Figure 1 A physical image of the product provided in Example 1;

[0034] Figure 2 This is a physical image of the product provided in Example 2;

[0035] Figure 3 This is a physical image of the product provided in Example 3;

[0036] Figure 4 This is a physical image of the product provided in Example 4;

[0037] Figure 5 The product image provided for Comparative Example 1. Detailed Implementation

[0038] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The raw materials used in the following embodiments of the present invention are all commercially available.

[0039] Example 1

[0040] S1) Add 26 parts by weight of neopentyl glycol and 2 parts by weight of diethylene glycol to a reactor equipped with a stirrer and reflux, turn on the stirrer and heat; then add 26 parts by weight of recycled PET particles and 0.3 parts by weight of catalyst, raise the temperature to 150°C, the recycled PET particles begin to melt, continue to raise the temperature to 220°C, and react for 60 minutes until all the recycled PET particles have melted; wherein the catalyst:

[0041] Including MX and NX catalysts, where M is Zn 2+ N is R1 is CH3, X is RAcO - R is CH3, and the ratio of MX to NX is 3:1.

[0042] S2) Under a nitrogen atmosphere, 30 parts by weight of the molten alcoholysis product obtained in S1), 25 parts by weight of isophthalic acid, 6 parts by weight of maleic anhydride, 6 parts by weight of acetic anhydride, and 60 parts by weight of propylene glycol were stirred and refluxed at approximately 160°C for 1 hour. The temperature was then gradually increased to 220°C, held under vacuum for 2 hours, until the acid value of the system reached 40 mg KOH / g, at which point heating was stopped. Once the system temperature dropped to 80°C, 15 parts by weight of styrene diluent and 0.04 parts by weight of 1,4-hydroquinone polymerization inhibitor were added, and the mixture was stirred mechanically for 3 hours. The product was then cooled to below 50°C to obtain a liquid resin suitable for compression molding and recycling of PET.

[0043] S3) Add 4 parts by weight of sodium alginate as a thickener to the liquid resin suitable for compression molding obtained from the above-mentioned PET recycling, and add 1.0 part by weight of benzoyl peroxide curing agent. Heat to 80°C and stir thoroughly until homogeneous. After stirring for 60 minutes, a prepolymerized mixed slurry can be obtained.

[0044] S4) Add 0.8 parts by weight of color paste and 1.0 parts by weight of iridescent pearl to the prepolymerized mixed slurry obtained above. Spread the slurry evenly in a mold. Set the mold temperature to 130°C, the mold pressure to 10MPa, and the molding time to 180 seconds. A blank with an iridescent pearl effect can be obtained by high-temperature molding. After stamping, cutting, and polishing, the resulting blank will be a iridescent pearl button made from recycled PET molding resin (see details). Figure 1 ).

[0045] Tested according to the international standard ISO 105-C06-2010 "Color fastness to domestic and commercial washing", the color fastness to washing is grade 4.0; tested according to the international standard ISO 105-D01-2010 "Color fastness to dry cleaning", the color fastness to dry cleaning is grade 4.0; tested according to the international standard ISO 105-X11-1994 "Color fastness to heat and pressing", the color fastness to ironing is grade 4.0.

[0046] Following the method in Example 1, colorful pearlescent buttons made from recycled PET molding resin were mass-produced, and the yield was measured to be 98%.

[0047] Example 2

[0048] S1) Add 26 parts by weight of neopentyl glycol and 2 parts by weight of diethylene glycol to a reactor equipped with a stirrer and reflux, turn on the stirrer and heat; then add 28 parts by weight of recycled PET particles and 0.3 parts by weight of catalyst, raise the temperature to 150°C, the recycled PET particles begin to melt, continue to raise the temperature to 230°C, and react for 60 minutes until all the recycled PET particles have melted; wherein the catalyst:

[0049] Including MX and NX catalysts, where M is Mn 2+ N is R1 is C2H5, X is RAcO - R is C2H5, and the ratio of MX to NX is 3:1.

[0050] S2) Under a nitrogen atmosphere, 30 parts by weight of the molten alcoholysis product obtained in S1), 25 parts by weight of isophthalic acid, 8 parts by weight of maleic anhydride, 8 parts by weight of acetic anhydride, and 60 parts by weight of dipropylene glycol were stirred and refluxed at approximately 160°C for 1 hour. The temperature was then gradually increased to 230°C, held under vacuum for 2 hours, until the acid value of the system reached 45 mg KOH / g, at which point heating was stopped. Once the system temperature dropped to 80°C, 15 parts by weight of HEA diluent and 0.04 parts by weight of tert-butylhydroquinone (TBHQ) polymerization inhibitor were added, and the mixture was stirred mechanically for 3 hours. The product was then cooled to below 50°C to obtain a liquid resin suitable for compression molding and recycling of PET.

[0051] S3) Add 4 parts by weight of β-cyclodextrin as a thickener to the liquid resin suitable for compression molding obtained from the above-mentioned PET recycling, and add 1.2 parts by weight of methyl ethyl ketone curing agent. Heat to 80°C and stir thoroughly until homogeneous. After stirring for 60 minutes, a prepolymerized mixed slurry can be obtained.

[0052] S4) Add 1.2 parts by weight of color paste and 1.0 parts by weight of iridescent pearl to the prepolymerized mixed slurry obtained above. Place the slurry in a mold, set the mold temperature to 130°C, the mold pressure to 10MPa, and the molding time to 200 seconds. A blank with an iridescent pearl effect can be obtained by high-temperature molding. After stamping, cutting, and polishing, the resulting blank will be a iridescent pearl button made from recycled PET molding resin (see details). Figure 2 ).

[0053] Tested according to the international standard ISO 105-C06-2010 "Color fastness to domestic and commercial washing", the color fastness to washing is grade 4.0; tested according to the international standard ISO 105-D01-2010 "Color fastness to dry cleaning", the color fastness to dry cleaning is grade 4.0; tested according to the international standard ISO 105-X11-1994 "Color fastness to heat and pressing", the color fastness to ironing is grade 4.0.

[0054] Following the method in Example 2, colorful pearlescent buttons made from recycled PET molding resin were mass-produced, and the yield was measured to be 99%.

[0055] Example 3

[0056] S1) Add 28 parts by weight of neopentyl glycol and 2 parts by weight of diethylene glycol to a reactor equipped with a stirrer and reflux, turn on the stirrer and heat; then add 30 parts by weight of recycled PET particles and 0.4 parts by weight of catalyst, raise the temperature to 150°C, the recycled PET particles begin to melt, continue to raise the temperature to 240°C, and react for 90 minutes until all the recycled PET particles have melted; the catalyst:

[0057] Including MX and NX catalysts, where M is Mg 2+ N is Y is Cl - X is RACO - R is CH3, R1 is CH3, and R2 is CH3. The ratio of MX to NX is 4:1.

[0058] S2) Under a nitrogen atmosphere, 32 parts by weight of the molten alcoholysis product obtained in S1), 25 parts by weight of itaconic acid, 10 parts by weight of maleic anhydride, 10 parts by weight of acetic anhydride, and 60 parts by weight of tripropylene glycol were stirred and refluxed at approximately 160°C for 1 hour. The temperature was then gradually increased to 240°C, held under vacuum for 2 hours, until the acid value of the system reached 50 mg KOH / g, at which point heating was stopped. Once the system temperature dropped to 80°C, 15 parts by weight of HPA diluent and 0.04 parts by weight of 1,4-benzoquinone polymerization inhibitor were added, and the mixture was stirred mechanically for 3 hours. The product was then cooled to below 50°C to obtain a liquid resin suitable for compression molding and recycling of PET.

[0059] S3) Add 5 parts by weight of hydroxymethyl cellulose as a thickener to the liquid resin suitable for compression molding obtained from the above-mentioned PET recycling, and add 1.0 part by weight of cyclohexanone peroxide curing agent. Heat to 80°C and stir thoroughly for 60 minutes to obtain the prepolymerized mixed slurry.

[0060] S4) Add 1.5 parts by weight of color paste and 1.5 parts by weight of iridescent pearl to the prepolymerized mixed slurry obtained above. Place the slurry in a mold, set the mold temperature to 140°C, the mold pressure to 12MPa, and the molding time to 220 seconds. A blank with an iridescent pearl effect can be obtained by high-temperature molding. After stamping, cutting, and polishing, the resulting blank will be a iridescent pearl button made from recycled PET molding resin (see details). Figure 3 ).

[0061] Tested according to the international standard ISO 105-C06-2010 "Color fastness to domestic and commercial washing", the color fastness to washing is grade 4.0; tested according to the international standard ISO 105-D01-2010 "Color fastness to dry cleaning", the color fastness to dry cleaning is grade 4.0; tested according to the international standard ISO 105-X11-1994 "Color fastness to heat and pressing", the color fastness to ironing is grade 4.0.

[0062] Following the method in Example 3, colorful pearlescent buttons made from recycled PET molding resin were mass-produced, and the yield was measured to be 98%.

[0063] Example 4

[0064] S1) Add 28 parts by weight of neopentyl glycol and 2 parts by weight of diethylene glycol to a reactor equipped with a stirrer and reflux, turn on the stirrer and heat; then add 32 parts by weight of recycled PET particles and 0.4 parts by weight of catalyst, raise the temperature to 150°C, the recycled PET particles begin to melt, continue to raise the temperature to 250°C, and react for 90 minutes until all the recycled PET particles have melted; the catalyst:

[0065] Including MX and NX catalysts, where M is Sb 2+ N is X is Cl - R1 is C2H5 and R2 is C2H5. The ratio of MX to NX is 4:1.

[0066] S2) Under a nitrogen atmosphere, 32 parts by weight of the molten alcoholysis product obtained in S1), 25 parts by weight of itaconic acid, 10 parts by weight of maleic anhydride, 10 parts by weight of acetic anhydride, and 60 parts by weight of butanediol were stirred and refluxed at approximately 160°C for 1 hour. The temperature was then gradually increased to 250°C, held under vacuum for 2 hours, until the acid value of the system reached 55 mg KOH / g, at which point heating was stopped. Once the system temperature dropped to 80°C, 15 parts by weight of HEMA diluent and 0.04 parts by weight of methylhydroquinone (THQ) polymerization inhibitor were added, and the mixture was stirred mechanically for 3 hours. The product was then cooled to below 50°C to obtain a liquid resin suitable for compression molding and recycling of PET.

[0067] S3) Add 5 parts by weight of sodium proteinate as a thickener to the liquid resin suitable for compression molding obtained from the above-mentioned PET recycling, and add 1.2 parts by weight of tert-butyl peroxide curing agent. Heat to 80°C and stir thoroughly until homogeneous. After stirring for 60 minutes, a prepolymerized mixed slurry can be obtained.

[0068] S4) Add 2.0 parts by weight of color paste and 1.5 parts by weight of iridescent pearl to the prepolymerized mixed slurry obtained above. Place the slurry in a mold, set the mold temperature to 140°C, the mold pressure to 12MPa, and the molding time to 240 seconds. A blank with an iridescent pearl effect can be obtained by high-temperature molding. After stamping, cutting, and polishing, the resulting blank will be a iridescent pearl button made from recycled PET molding resin (see details). Figure 4 ).

[0069] Tested according to the international standard ISO 105-C06-2010 "Color fastness to domestic and commercial washing", the color fastness to washing is grade 4.0; tested according to the international standard ISO 105-D01-2010 "Color fastness to dry cleaning", the color fastness to dry cleaning is grade 4.0; tested according to the international standard ISO 105-X11-1994 "Color fastness to heat and pressing", the color fastness to ironing is grade 4.0.

[0070] Following the method in Example 4, colorful pearlescent buttons made from recycled PET molding resin were mass-produced, and the yield was measured to be 99%.

[0071] Comparative Example 1

[0072] Following the implementation of Example 1 in patent CN110511366B, a resin button made from recycled PET polyester plastic bottles was obtained (see details). Figure 5 ).

[0073] Tested according to the international standard ISO 105-C06-2010 "Color fastness to domestic and commercial washing", the color fastness to washing is grade 4.0; tested according to the international standard ISO 105-D01-2010 "Color fastness to dry cleaning", the color fastness to dry cleaning is grade 4.0; tested according to the international standard ISO 105-X11-1994 "Color fastness to heat and pressing", the color fastness to ironing is grade 4.0.

[0074] According to the corresponding testing standards and methods, the performance of the products obtained in the above embodiments and comparative examples was tested, and the results are shown in Table 1.

[0075] Table 1. Performance data of the products obtained from the examples and comparative examples.

[0076]

[0077]

[0078] In summary, the method for preparing molding resin and colorful pearlescent buttons by recycling PET provided by this invention has the following beneficial effects:

[0079] (1) By selecting maleic anhydride and acetic anhydride as activators, the present invention effectively improves the activity and heat resistance of the resin. At the same time, during the resin polymerization stage, a suitable thickener is selected to adjust the resin viscosity. The resulting resin is suitable for high-temperature mold molding process, so that it can quickly fill the mold cavity under certain molding temperature and pressure, and the button shape is more full.

[0080] (2) The buttons made by this invention can not only meet the functional requirements that buttons must have when used in clothing accessories, such as color fastness to washing, color fastness to dry cleaning, and color fastness to machine washing, but also meet the requirements of high temperature aging test and test under high temperature and high humidity environment. They have broad market prospects, build the core competitiveness of the company's new products and new technologies, and lead the future development and direction of the button industry.

[0081] (3) The process technology of this invention is simple to operate, reduces the dependence on the experience of technical personnel, and is suitable for both large-scale and small-scale operations; at the same time, it effectively reduces the product defect rate, improves production efficiency, and reduces raw material waste and labor costs.

[0082] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing colorful pearlescent buttons from recycled PET, characterized in that, Includes the following steps: S1) The recycled PET particles are put into a reactor containing an alcoholysis agent and a catalyst for depolymerization. The stirrer is turned on and the reactor is heated to carry out an alcoholysis melting reaction to obtain alcoholysis products. S2) Using the alcoholysis product obtained in S1, add at least one of isophthalic acid or unsaturated dicarboxylic acid, an activator, and a diol. Stir and reflux the reaction at 155℃~165℃, control the steam temperature at 80℃~110℃, and then gradually raise the temperature to 220℃~250℃ and continue to react under vacuum for 1h~2h. Stop heating when the acid value of the system reaches 40mgKOH / g~60mgKOH / g. When the system temperature drops below 100℃, start adding diluent and polymerization inhibitor. Mix evenly under nitrogen atmosphere and mechanical stirring to obtain a liquid resin suitable for compression molding for PET recycling. The active agents are maleic anhydride and acetic anhydride; The proportions of each component are as follows: 20-30 parts by weight of at least one of isophthalic acid or unsaturated dicarboxylic acid; 5-15 parts by weight of maleic anhydride; 5-15 parts by weight of acetic anhydride; 60-80 parts by weight of diol. S3) Add a thickener to the liquid resin obtained above and mix thoroughly. At the same time, add a curing agent and thicken and prepolymerize at a certain temperature. After a period of time, a prepolymerized mixed slurry can be obtained. The thickener is one or a mixture of several of starch, sodium alginate, β-cyclodextrin, polysaccharide derivatives, carboxymethyl cellulose, sodium proteate, and casein. The specific gravity of the thickener is 3.0 to 6.0 parts by weight. S4) Add color paste and iridescent pearl to the prepolymerized mixed slurry obtained above, and mold it at a certain temperature and pressure to obtain a blank with iridescent pearl effect through high temperature molding. After stamping, cutting, button making and polishing, the blank obtained above can be used to obtain iridescent pearl buttons made of PET recycled molding resin. The button has a color fastness to washing, dry cleaning, or heat pressing of grade 4.

0.

2. The preparation method according to claim 1, characterized in that, The alcoholysis agent described in S1) is a mixture of neopentyl glycol and diethylene glycol, with a mass ratio of neopentyl glycol to diethylene glycol of (15:1) to (5:1).

3. The preparation method according to claim 1, characterized in that, The catalyst described in S1) is a mixture of MX and NX; Specifically, M is Zn. 2+ Mn 2+ Mg 2+ Co 2+ Sb 2+ Cu 2+ Sn 2+ A mixture of one or more of them, where N is , , , A mixture of one or more of the following, where X is Cl - WO4 2- H2PO4 - AlCl4 - ,RAcO - R is one or more of CH3, C2H5, and C6H5, R1 is one or more of CH3, C2H5, and C6H5, R2 is one or more of CH3, C2H5, and C6H5, R3 is one or more of CH3, C2H5, and C6H5, and R4 is one or more of CH3, C2H5, and C6H5.

4. The preparation method according to claim 3, characterized in that, The catalyst is a mixture of MX and NX, wherein the mass ratio of MX to NX is (3:1) to (6:1).

5. The preparation method according to claim 1, characterized in that, The mass ratio of PET recycled particles, alcoholysis agent, and catalyst mentioned in S1) is: PET recycled particles: alcoholysis agent: catalyst = (25%~32%): (20%~30%): (0.2%~0.4%).

6. The preparation method according to claim 1, characterized in that, The heating temperature described in S1) is 220℃~250℃, and the alcoholysis time is 60min~90min.

7. The preparation method according to claim 1, characterized in that, The unsaturated dicarboxylic acid mentioned in S2) is one or a mixture of maleic acid, trans-butenedioic acid, and itaconic acid; the diol is one or a mixture of ethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, and butanediol.

8. The preparation method according to claim 1, characterized in that, The ratio of the diluent and the polymerization inhibitor described in S2) is (15~25 parts by weight) : (0.04~0.06 parts by weight); the diluent is one or more of styrene, HEA, HPA, HEMA, HPMA, MMA, dimethacrylate, and butyl acrylate; the polymerization inhibitor is one or more of 1,4-hydroquinone, tert-butylhydroquinone, 2,5-di-tert-butylhydroquinone, 1,4-benzoquinone, and methylhydroquinone.

9. The preparation method according to claim 1, characterized in that, The curing agent mentioned in S3) is one or more of methyl ethyl ketone peroxide, cyclohexanone peroxide, and benzoyl peroxide, and the specific gravity of the curing agent is 0.6 to 2.0 parts by weight.

10. The preparation method according to claim 1, characterized in that, The specific gravity of the color paste mentioned in S4) is 0.1~2 parts by weight, the specific gravity of the multicolored pearlescent pigment is 0.5~2 parts by weight, the molding temperature is 120℃~140℃, the molding pressure is 10MPa~15MPa, and the molding time is 120s~300s.

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