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CN-122011351-A - Anti-graffiti organosilicon modified polyester resin for powder coating and preparation method thereof

CN122011351ACN 122011351 ACN122011351 ACN 122011351ACN-122011351-A

Abstract

The invention discloses an anti-graffiti organosilicon modified polyester resin for powder coating and a preparation method thereof. The anti-graffiti organic silicon modified polyester resin for the powder coating comprises, by mass, 30-50 parts of polyol, 40-60 parts of polybasic acid, 0.1-0.5 part of esterification catalyst, 3-8 parts of acidolysis agent, 5-15 parts of organic silicon modifier, 0.2-1.0 part of antioxidant and 0.1-0.5 part of curing accelerator. The resin has a glass transition temperature (Tg) of 59-65 ℃, an acid value of 30-36 mgKOH/g, a melt viscosity (200 ℃) of 4000-800 Pa-s, a number average molecular weight Mn of 3000-800 g/mol and a molecular weight distribution (PDI) of about 2.0. The anti-graffiti coating has the advantages of 1) excellent and durable anti-graffiti performance, 2) excellent weather resistance and good comprehensive mechanical properties.

Inventors

  • LIU YI
  • QIU FENGLI
  • TANG MINGLIN
  • XU GUOHUI
  • YANG XIAOWEI
  • Mei Minchao
  • CHEN GUANGDI

Assignees

  • 浙江传化天松新材料有限公司

Dates

Publication Date
20260512
Application Date
20251226

Claims (10)

  1. 1. An anti-graffiti organosilicon modified polyester resin for powder coating, which is characterized in that, The anti-graffiti organosilicon modified polyester resin for the powder coating comprises the following components in percentage by mass: 30-50 parts of polyalcohol; 40-60 parts of polybasic acid; 0.1-0.5 part of esterification catalyst; 3-8 parts of acidolysis agent; 5-15 parts of an organosilicon modifier; 0.2-1.0 part of antioxidant; 0.1-0.5 part of curing accelerator; The glass transition temperature (Tg) of the resin is 59-65 ℃, the acid value is 30-36 mgKOH/g, and the melt viscosity (200 ℃) is 4000-800 mPa.s; The resin has a number average molecular weight Mn of 3000 to 8000g/mol and a molecular weight distribution (PDI) of about 2.0.
  2. 2. The anti-graffiti silicone-modified polyester resin for powder coating according to claim 1, wherein, The polyalcohol is any one or more of neopentyl glycol, 2-methyl-1, 3-propanediol, 1, 4-cyclohexanedimethanol and 1, 6-hexanediol.
  3. 3. The anti-graffiti silicone-modified polyester resin for powder coating according to claim 1, wherein, The polybasic acid is any one or more of terephthalic acid, isophthalic acid and adipic acid; Wherein the molar ratio of the aromatic dibasic acid is not less than 60%.
  4. 4. The anti-graffiti silicone-modified polyester resin for powder coating according to claim 1, wherein, The esterification catalyst is any one or more of monobutyl tin oxide, dibutyl tin dilaurate and tetraisopropyl titanate.
  5. 5. The anti-graffiti silicone-modified polyester resin for powder coating according to claim 1, wherein, The acidolysis agent is isophthalic acid, adipic acid or trimellitic anhydride and is used for adjusting the molecular chain structure and the final acid value in the later period of the reaction.
  6. 6. The anti-graffiti silicone-modified polyester resin for powder coating according to claim 1, wherein the silicone modifier has the formula: (R1R2SiO)m–[(R3O)SiR 4 R 5 ]n–(SiR 6 R 7 O)p Wherein: R1, R2, R 4 ,R 5 ,R 6 ,R 7 are each independently selected from C1-C6 alkyl or phenyl, preferably methyl or phenyl; r3 is selected from H or C1-C4 alkyl, preferably H (hydroxy), methoxy or ethoxy, m, n and p are integers, m+p is more than or equal to 1, n is more than or equal to 1, m+n+p is more than or equal to 3 and less than or equal to 20, and the value of n/(m+n+p) is controlled to be 0.2-0.5.
  7. 7. The anti-graffiti silicone-modified polyester resin for powder coating according to claim 6, wherein, The organosilicon modifier is polysiloxane oligomer with hydroxyl or alkoxy on a terminal group or a side chain, and the number average molecular weight (Mn) is a, so that the quantitative relation a=800-2000 g/mol is satisfied.
  8. 8. The anti-graffiti silicone-modified polyester resin for powder coating according to claim 6, wherein, The antioxidant is a mixture of hindered phenols and phosphite antioxidants; the antioxidant is a mixture of antioxidant 1010 and antioxidant 168.
  9. 9. The anti-graffiti silicone-modified polyester resin for powder coating according to claim 6, wherein, The curing accelerator is any one or two of ethyl triphenylphosphine bromide and 2-methylimidazole and is used for adjusting the resin curing reaction activity.
  10. 10. A method for preparing the anti-graffiti organosilicon modified polyester resin for powder coating, which is characterized in that: S1, a prepolymerization stage Adding a polyol component, a polybasic acid component, all organosilicon modifier, an esterification catalyst and an antioxidant according to the formula amount in a reaction kettle; introducing nitrogen to replace air, keeping weak nitrogen protection in the subsequent reaction, slowly heating to 150-180 ℃, and stirring after the materials are melted; continuously heating to 200-230 ℃ and carrying out esterification reaction at the temperature; separating water generated by esterification through a fractionating column, and monitoring the water yield and the acid value of a reaction system until the prepolymerization stage is finished; s2, sampling and detecting, namely adding an acidolysis agent component into the prepolymer obtained in the step S1 when the acid value is reduced to 12-15 mgKOH/g, heating to 230-240 ℃ for reaction, and carrying out heat preservation reaction for 90-120 minutes; S3, sampling and detecting, namely when the acid value is increased to 45-48 mgKOH/g, starting vacuumizing, gradually controlling the vacuum to-0.097 to-0.099 Mpa, and reacting for 90-120 minutes under the vacuum condition of 230-235 ℃; S4, sampling and detecting, cooling to 200 ℃ when the acid ester reaches 32-36 mgKOH/g, adding an antioxidant and a curing accelerator, stirring and reacting for 15-30 minutes, discharging, cooling and crushing to obtain the light yellow transparent solid resin.

Description

Anti-graffiti organosilicon modified polyester resin for powder coating and preparation method thereof Technical Field The invention relates to the technical field of polyester resin of powder coating, in particular to anti-graffiti organosilicon modified polyester resin for powder coating and a preparation method thereof. Background The powder coating is used as a coating technology with environmental protection, high utilization rate and excellent performance, and is widely applied in the fields of building materials, household appliances, traffic, industrial protection and the like. However, the surface energy of the common powder coating is higher, the resistance to graffiti media such as oily mark pens, paint spraying, sticky objects and the like is weak, stains are difficult to remove, and the coating is easy to damage due to strong cleaning. In the prior art: CN101565579a discloses a hyper "javascript: openDetailedInfo ('CN 101565579a', '11')" anti-graffiti anti-sticking paint and its preparation method, and the paint is a paint with excellent comprehensive properties, more self-cleaning property, because the fluorine-containing polymer has the characteristics of high and low temperature resistance, chemical resistance, non-adhesion, low friction and the like. The production method of the coating is simple, and the operation is convenient, and can be used for resisting the pollution of modern urban public facilities. CN113512342a discloses an anti-graffiti powder coating which has a small compatibility with oily substances such as oil stains or ink, and when the coating layer is polluted by graffiti and oil stains, the pollution can be easily cleaned and no stain is left. In order to solve the problem of anti-graffiti, the prior art mainly adopts the following approaches: 1) And adding an anti-graffiti auxiliary agent, namely adding a fluorine-containing or silicon-containing leveling agent and an auxiliary agent into the powder coating formula. The method is simple, but has limited and non-durable anti-graffiti effect, the auxiliary agent is easy to migrate and separate out, the performance decay is quick after long-term use or outdoor exposure, and the interlayer adhesive force can be influenced. 2) And (3) coating the anti-graffiti varnish on the surface of the coating, wherein a layer of liquid anti-graffiti varnish is additionally sprayed or brushed on the surface of the coating. The method has good effect, increases construction procedures and cost, and can also have the problems of poor adhesion and unmatched weather resistance with the bottom powder coating. 3) Preparation of low surface energy resins with low surface energy, such as fluorocarbon resins or silicone resins, are synthesized starting from the resin structure design. Fluorocarbon resins are extremely high in cost and limit their wide application, whereas simple silicone resins, although low in surface energy, have poor compatibility with other components of the powder coating, resulting in poor mechanical strength and adhesion of the coating, and are difficult to be directly used for preparing high-performance powder coatings. The polyester resin is one of the main base resins of the powder coating and has excellent comprehensive performance. The combination of excellent properties of silicones (low surface energy, heat resistance, weather resistance) with good film forming properties, mechanical strength and compatibility of polyester resins is an ideal technical route. Common silicone modified polyester methods are physical blending and chemical modification. The physical blending same has the problems of poor compatibility, easy phase separation and unstable performance. Chemical modification, particularly by introducing organosilicon segments or siloxane bonds into the polyester backbone or side chains by polycondensation, is a preferred method. However, existing chemical modification techniques still face challenges: 1) The modification degree and the compatibility are balanced, namely, the low content of the organic silicon component can cause unobvious anti-graffiti effect, and the high content can cause poor compatibility with the polyester chain segment, thereby causing the deterioration of the light performance of the coating; 2) In the reaction control and structural design, how to accurately regulate and control the reaction process of the organosilicon monomer or prepolymer, polyester polyol and polybasic acid, and avoid excessive hydrolysis, condensation or rearrangement of siloxane bonds in the high-temperature esterification process, so that the preparation of the modified resin with definite structure and controllable performance is a difficult point of the technology; 3) In the maintenance of the comprehensive properties, the original key properties of the polyester resin such as excellent leveling property, reactivity, storage stability, impact resistance, bending property, adhesive force and the like must be m