RU2802475C1 - Pet-based pes - Google Patents

Abstract

FIELD: chemical industry.

SUBSTANCE: polyester resin based on polyethylene terephthalate and a method for producing polyester resin. The synthesis of polyester resin based on polyethylene terephthalate is carried out at the following ratio of components in parts by weight: polyethylene terephthalate - 23.00-28.00; propylene glycol - 23.00-28.00; zinc acetate - 0.50-2.50; maleic anhydride - 14.00-16.50; hydroquinone - 0.03-0.08; styrene - 30.00-35.00. As sources of ethylene glycol and terephthalic anhydride, glycolysis products of polyethylene terephthalate in propylene glycol are used. Zinc acetate is used as a glycolysis catalyst. Maleic anhydride is used as a reagent responsible for the reactivity of the finished resin. Hydroquinone is used as a stabilizer. Glycolysis is carried out in the presence of a zinc acetate catalyst for 6 hours at a temperature of 210±2°C, then the reaction mixture is cooled to 70-90°C, maleic anhydride is introduced into the reaction mixture and heated to 130°C is maintained for 1 hour, followed by an increase in temperature to 180°C and exposure for 1 hour, using a direct refrigerator, water and unreacted reagents are distilled off and the acid number of the mixture is adjusted to 35 mg/g and hydroquinone is introduced into the mixture, the temperature of the mixture is lowered to 90-100°C and the reaction mixture is mixed with styrene.

EFFECT: obtaining terephthalic polyester resins with increased chemical resistance by relatively inexpensive methods using waste recycled plastics based on polyethylene terephthalate.

3 cl, 2 tbl, 3 ex

Description

The invention relates to a polyester resin, in particular, to a polyester resin composition based on terephthalic acid and maleic anhydride, and can be used for the manufacture of building materials, such as pultrusion, polymer concrete.

The global unsaturated polyester resins (UPR) market size was US$11,579.6 million in 2019 and is projected to reach US$16,965.7 million by 2027, growing at a CAGR of 5% during the forecast period. ,9%.

Unsaturated polyester resin is a linear polymer compound with an unsaturated double bond and an ester bond. It is formed by condensation polymerization of a saturated dihydric alcohol of a dihydric acid or a dihydric alcohol of an unsaturated dihydric acid. This material is a printable liquid polymer that remains solid when cured with styrene. When combined with fiberglass, it can exhibit properties such as strength and durability. It is also used for opaque panels, aircraft ducts and to provide aesthetic appeal.

The growing demand for this product can be attributed to the growth in the construction industry, where it is used for wood paints, flat laminated panels, ribbed panels, artificial cement and sanitary ware. In addition, this product also finds application in frames, ducts and pipes, panels, interior and exterior components of vehicles, boats and aircraft. Consequently, the expansion of the automotive, marine and aviation industries will stimulate the production of unsaturated polyester resins.

The limiting factor for the growth of polyester resin production on the Russian market is the lack of capacity. Over the past 30 years, not a single plant has been built (source www.rcc.ru). Global unsaturated polyester resin production capacity is currently estimated to be approximately 7 million tonnes per year, according to IHS Markit Ltd. Of these, about 1 million tons per year are located in Europe (including the CIS). There are more than 30 factories in Europe. The largest five international concerns own about 60% of European production capacity. These include Polynt-Reichhold, DSM, Ashland and Scott Bader. There are seven domestic manufacturers on the Russian market - Dugalak (Yaroslavl), Kamensky Combine (Kamensk-Shakhtinsky, Rostov region), Kamtex-Polyesters (Perm), Perm Polyesters (Perm) ), "Yaroslavl Polyester Plant" (Yaroslavl), "Electroizolit" (Khotkovo, Moscow region) and LLC "Raduga-sintez" (Electrougli, Moscow region). In 2016, three companies accounted for about 75% of total production. Over the past seven years, Russian production of unsaturated polyester resins has almost tripled, and the annual growth rate shows extremely positive dynamics.

There is a known method for obtaining unsaturated polyester resins based on dietalen glycol, forandicarbon acid, maleine anhydrid (patent 2 760 519 RU, MPC C08G 63/18, C08G 63/52, C08G 63/54, C08G 63/66, C08G 63 /672, C08G 63/676, published 11/26/2021, Bulletin No. 33). The method involves preparing a reaction mixture with the following molar ratio of components: 2,5-furandicarboxylic acid - 0.26-0.33, maleic anhydride - 0.67-0.74, diethylene glycol - 1.1, heating the reaction mixture to 200°C , and holding at this temperature until the acid number reaches 40-50, further cooling to a temperature of 90-100°C and introducing hydroquinone as a stabilizer, adding 30 wt. to the finished reaction mixture. % styrene.

The disadvantage of this technology is the use of furandicarboxylic acid, which has an increased melting point of 342°C and at the moment there are no enterprises for the production of 2,5-furandicarboxylic acid for industrial needs, therefore, the price of the final product will be significantly higher than analogues.

The technology for producing polyester resins based on the following monomers is known: diethylene glycol, ethylene glycol, maleic acid, diphenic acid (AS No. 132816). This method involves heating the reaction mixture at a temperature of 160-170°C in certain molar ratios:

- diethylene glycol, maleic anhydride and diphenic acid in a molar ratio of 1.1:0.67:0.33;

- ethylene glycol, maleic anhydride and diphenic acid in a molar ratio of 1.1:0.5:0.5.

The synthesis is carried out in an inert gas atmosphere until the acidity is brought to 35-40 mg(KOH)/g(resin).

The disadvantage of this synthesis technology is the use of diphenic acid produced from non-renewable raw materials. Also, the use of ethylene glycol in the synthesis process worsens the interaction of the finished polyester resin with styrene.

The closest to the claimed technical solution is a method for producing unsaturated polyester resins formed from a mixture of monomers: 1,4-butanediol, 2,5-furandicarboxylic acid, terephthalic acid, ethylene glycol or 2,5-furandicarboxylic acid (patent 2,606,515 RU, IPC C08G63/16, C08G63/183, published 01/10/2017, bulletin No. 1). The synthesis is carried out: by mixing the monomers: 2,5-furandicarboxylic acid or its lower alkyl ester, 1,4-butanediol, isosorbide or a combination thereof, terephthalic acid, ethylene glycol and a catalyst to prepare the reaction mixture; gradual heating with constant stirring in a nitrogen stream to a temperature of 200-230°C, and maintaining the first temperature for 8-12 hours; gradual heating of the reaction mixture to the second temperature over 12-48 hours; removing water from the reaction mixture; and recovering the resulting copolyester.

The disadvantages of this technology for producing unsaturated polyester resins are the long time of their synthesis, thermoplasticity, the use of 2,5-furandicarboxylic acid and primary terephthalic acid, which have relatively high melting points of 342°C and 427°C, respectively. As a result, high melting temperatures during synthesis will have relatively high energy costs.

The objective of the invention is to develop a technology for producing terephthalic polyester resins at relatively low melting temperatures for phthalic anhydride using recycled waste from polyethylene terephthalate bottles as raw materials.

The technical result of the invention is to expand the arsenal of technologies for producing terephthalic polyester resins, which have increased chemical resistance, by relatively inexpensive methods using waste secondary plastics based on polyethylene terephthalate. The use of recycled polyethylene terephthalate will reduce the cost of finished products due to relatively cheap raw materials and lower energy costs, since the glycolysis temperature is significantly lower than the melting point of primary terephthalic acid.

The specified technical result is achieved by the proposed technology for producing polyester resin, which includes the production of a reaction mixture based on polyethylene terephthalate, propylene glycol, zinc acetate, maleic anhydride, hydroquinone, styrene. Synthesis occurs at the following ratio of components in parts by weight. (per 100.00 parts by weight of polyester resin):

polyethylene terephthalate 23.00-28.00 propylene glycol 23.00-28.00 zinc acetate 0.50-2.50 maleic anhydride 14.00-16.50 hydroquinone 0.03-0.08 styrene 30.00-35.00

Distinctive features of the claimed invention are the use of ethylene glycol and terephthalic anhydride, products of polyethylene terephthalate processing, as sources. Zinc acetate is used as a glycolysis catalyst. Additionally, maleic anhydride (the main component responsible for reactivity) and hydroquinone as a stabilizer are introduced into the synthesized mixture. Next, at the end of the process, the finished polyester resin is mixed with styrene as a solvent and reagent for copolymerization, which ensures an acceptable polymerization rate and a high depth of curing of the finished material.

The ratio of reagents was selected experimentally.

The claimed technical solution is implemented as follows.

Glycolysis of PET with propylene glycol or dipropylene glycol in the presence of a zinc acetate catalyst is carried out in a reactor equipped with a stirrer, reflux condenser, thermometer and bubbler for supplying inert gas. Zinc acetate was used as a catalyst for the glycolysis process. Mixing of ingredients is carried out for 6 hours at a stirrer speed of 80-100 rpm and a temperature of 210±2°C.

At the end of the glycolysis process, the reaction mixture is cooled to 70-90°C, and maleic anhydride is loaded into the flask. After loading the reagents into the reaction flask, it is heated to 130°C with constant stirring and held for 1 hour for complete melting of maleic anhydride and its further reaction with a mixture of glycols. Next, the temperature rises to 180°C and is maintained for 1 hour. A direct refrigerator and a vacuum are connected to remove water and unreacted reagents. The synthesis is carried out until the acid number of the reaction mixture is less than 35 mg/g. After reaching the required acid number, the mixture is cooled with constant stirring. At a temperature of 170°C, a polymerization inhibitor (hydroquinone) is introduced to prevent the formation of a cross-linked three-dimensional polymer. After reducing the temperature of the mixture to 90-100°C, a solvent is added to it, preheated to 60-70°C. The synthesis process is carried out entirely in an inert gas atmosphere.

Examples of polyester resin compositions are presented in Table 1.

Table 1 - Examples of polyester resin compositions

Ingredients Ingredient content in the mixture, wt. h. 1 2 3 Polyethylene terephthalate 25.38 26.08 24.26 Propylene glycol 25.38 24.37 24.26 Zinc acetate 0.93 0.90 0.90 Maleic anhydride 16.28 15.62 15.56 Hydroquinone 0.03 0.03 0.024 Styrene 32.00 33.00 35.00 Total: 100.00 100.00 100.00

Studies of the physical and mechanical properties of polyester resin were carried out using standard methods: density according to GOST 18329–2014; styrene content was determined according to GOST 13549–78; relative viscosity was determined according to GOST 8420–74 using a VZ-246 type viscometer with a nozzle diameter of 6.0 mm; gelatinization time was determined according to GOST 22181–2015. The properties of the finished polyester resin are presented in Table 2.

Table 2 - Physical and mechanical properties of the finished polyester resin.

Indicator name Standard for the brand The value of the determined indicator Test method PN-1 PN-609-21M Appearance, color Transparent liquid without foreign inclusions Homogeneous liquid without foreign inclusions of a brown tint Clause 7.2 according to GOST 27952-2017 light to dark yellow yellow, green or brown Density at temperature (23.0±0.1)°C, g/cm ³ 1.137-1.148 1.165-1.180 1.139 GOST 18329-2014 Mass fraction of styrene, % 30-33 Not defined 32 GOST 13549-78 Conditional viscosity, s 16-31 20-32 22 GOST 8420-74 Gelatinization time, min 5-28 100-200 27 GOST 22181-2015

Thus, from the presented tables it is clear that the physical and mechanical properties of the proposed unsaturated polyester resins meet the basic requirements for polyester resins and can be used in various industries (for the automotive, construction, household industries, etc.) and create chemical-resistant polyester resins based on the products glycolysis of secondary polyethylene terephthalate.

Claims (3)

1. Polyester resin based on polyethylene terephthalate, propylene glycol, zinc acetate, maleic anhydride, hydroquinone, styrene, characterized in that the products of glycolysis of polyethylene terephthalate in propylene glycol are used as sources of ethylene glycol and terephthalic anhydride, zinc acetate is used as a catalyst for glycolysis, the synthesis is carried out as follows ratio of components in parts by weight: Polyethylene terephthalate 23.00-28.00 Propylene glycol 23.00-28.00 zinc acetate 0.50-2.50 maleic anhydride 14.00-16.50 hydroquinone 0.03-0.08 styrene 30.00-35.00 2. The method for producing polyester resin according to claim 1, characterized in that glycolysis is carried out in the presence of a zinc acetate catalyst for 6 hours at a temperature of 210±2°C, then the reaction mixture is cooled to 70-90°C, into the reaction mixture maleic anhydride is introduced as a reagent responsible for the reactivity of the finished resin, and heated to 130°C, held for 1 hour, followed by an increase in temperature to 180°C and held for 1 hour, then using a direct refrigerator, water and unreacted substances are distilled off reagents and bring the acid number of the mixture to 35 mg/g and introduce hydroquinone into the mixture as a stabilizer, lower the temperature of the mixture to 90-100°C and mix the reaction mixture with styrene, used as a solvent.