Unsaturated polyester resin for jade-like handicrafts and preparation method thereof

Abstract

An unsaturated polyester resin for jade-like handicrafts and a preparation method thereof belong to the technical field of polyester resins and comprise the following components: diethylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride, antioxidant, polymerization inhibitor, paraffin, stabilizer, ultraviolet absorber, whitening agent and diluent. The weight ratio of propylene glycol to methyl propylene glycol is 1.0-1.3:1, and the content of methyl propylene glycol in the total dihydric alcohol is 20-22%; the weight ratio of maleic anhydride to phthalic anhydride is 0.46-0.52:1; the preparation steps are as follows: 1) the raw materials and antioxidant are added into a reactor, and after warming, the temperature is kept for 0.5-1.0 h, and then the temperature is continuously increased; 2) after warming, the reaction is carried out for 2-3 h; dehydration is carried out until the acid value is 20-25 mgKOH / g; 3) the temperature is decreased, and the auxiliary agent is added and uniformly mixed to obtain the unsaturated polyester resin. The resin of the present application is water-white, and the liquid index and physical properties can meet the requirements of jade-like handicrafts.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polyester resin, and particularly relates to an unsaturated polyester resin for jade-imitating handicrafts and a preparation method thereof. BACKGROUND

[0002] The unsaturated polyester resin has been widely applied in many fields due to its good low-temperature curing process performance, simple operation process and moderate price. After being fully mixed with various fillers and auxiliary materials, the unsaturated polyester resin is poured into a mold for forming, and then subjected to demolding, polishing and polishing processes to form a resin handicraft with exquisite modeling and lifelike image. With the continuous improvement of modern living standards, people's demand for handicrafts is increasing, and the market potential of resin handicrafts is continuously released, showing extremely broad development prospects. At the same time, the quality requirements for resin handicrafts in the market are also continuously improved, especially in the field of jade-imitating handicrafts, which puts forward more stringent standards for the performance of resin.

[0003] The resin used for jade-imitating handicrafts needs to have colorless or light color characteristics to facilitate coloring, and can present brilliant colors and charming luster after processing and curing. In addition, the resin also needs to have high hardness and toughness, and good impact resistance and heat resistance. However, the existing unsaturated polyester resin for making handicrafts has the problems of color yellowing, luster reduction and physical strength reduction due to the absorption of ultraviolet rays by unstable chemical bonds in the resin molecules, which causes photodegradation reaction, molecular chain rupture and formation of color groups. SUMMARY

[0004] The technical problem to be solved by the present application is to overcome the deficiencies of the prior art and provide an unsaturated polyester resin for jade-imitating handicrafts and a preparation method thereof. The resin of the present application is water white, and the liquid index and physical properties can meet the requirements of jade-imitating handicrafts.

[0005] In order to achieve the above-mentioned purpose, the present application provides an unsaturated polyester resin for jade-imitating handicrafts, which consists of the following components in parts by weight: diethylene glycol 16.2-16.8 parts, methyl propylene glycol 6.0-6.6 parts, propylene glycol 6.6-7.8 parts, maleic anhydride 11.73-13 parts, phthalic anhydride 25-25.53 parts, antioxidant 0.052-0.058 parts, polymerization inhibitor 0.0038-0.0043 parts, paraffin 0.052-0.058 parts, stabilizer 0.0009-0.0012 parts, ultraviolet absorber 0.03-0.035 parts, whitening agent 0.0025-0.0035 parts and diluent 31.8418-32.6215 parts.

[0006] The weight ratio of propylene glycol to methyl propylene glycol is 1.0-1.3:1, and the proportion of methyl propylene glycol in the total dihydric alcohol is 20-22%; the weight ratio of maleic anhydride to phthalic anhydride is 0.46-0.52:1.

[0007] Preferably, the unsaturated polyester resin for the imitation jade handicraft product comprises the following components by mass percentage: diethylene glycol 16.5 parts, methyl propylene glycol 6.3 parts, propylene glycol 7.2 parts, maleic anhydride 12.4 parts, phthalic anhydride 25.3 parts, triphenyl phosphite 0.055 parts, hydroquinone 0.004 parts, paraffin 0.055 parts, cobalt isooctoate 0.001 parts, methyl styrene 32.15 parts, 2-(2'-hydroxy-5'-tert-octyl phenyl) benzotriazole 0.032 parts, 2,5-bis(5-tert-butyl-2-benzoxazolyl) thiophene 0.003 parts; the weight ratio of propylene glycol to methyl propylene glycol is 1.14:1, and the proportion of methyl propylene glycol in the total dihydric alcohol is 21%; the weight ratio of maleic anhydride to phthalic anhydride is about 0.49:1.

[0008] Propylene glycol can improve the wettability of the resin and promote the adhesion of the resin to the substrate due to its strong water absorption, but when the amount of propylene glycol is excessive, the hydroxyl group density is too high, which accelerates the oxidation side reaction to generate chromophoric groups at high temperature, and the resin prepared by increasing the amount of propylene glycol has a light yellow color, which affects the effect of the handicraft product. The branched structure of methyl propylene glycol reduces the molecular symmetry, inhibits the formation of crystals, and endows the resin with high stability, but excessive branching will increase the steric hindrance of the molecular chain; it has excellent chemical resistance, weather resistance and ultraviolet resistance.

[0009] When the weight ratio of propylene glycol to methyl propylene glycol is within the range of 1.0-1.3, the resin has a water-white state, which can make the color difference of the handicraft product <0.5; when the weight ratio of propylene glycol to methyl propylene glycol exceeds the range of 1.0-1.3, the resin color gradually changes from light yellow to yellow, and the color difference increases significantly. Excessive proportion of methyl propylene glycol can lead to increased molecular chain rigidity, limited crosslinking network, and fluctuation of exothermic peak temperature.

[0010] The weight ratio of propylene glycol to methyl propylene glycol is 1.0-1.3:1, which optimizes the flowability of the resin, and methyl propylene glycol strengthens the weather resistance and chemical resistance; the proportion of the two is within the range of 1.0-1.3:1, which balances the process performance and long-term stability.

[0011] Methylpropanediol accounts for 20-22% of the total amount of diols. This ratio range ensures that the long-chain flexible structure of methylpropanediol is fully integrated into the resin network, giving the product sufficient toughness to simulate the texture of jade, while avoiding excessive stretching strength. When the proportion of methylpropanediol exceeds 22%, the resin's hydrolysis resistance improves but the viscosity increases, affecting the uniformity of filler dispersion; when it is less than 20%, the UV aging resistance is insufficient, making it difficult to meet the long-term outdoor use requirements of jade imitation crafts.

[0012] The weight ratio of maleic anhydride to phthalic anhydride is 0.46-0.52:1. When the weight ratio of maleic anhydride to phthalic anhydride is less than 0.46, the reaction activity decreases, and the reaction rate also decreases. When the acid value reaches 20-25 mgKOH / g, the gel time becomes longer, the post-curing time is extended, the exothermic peak is lower, resulting in poor curing effect of the crafts, reduced physical properties, and low shrinkage after curing, which is not conducive to demolding. When the weight ratio of maleic anhydride to phthalic anhydride is higher than 0.52, the reaction activity increases, the reaction rate also increases, the crosslinking density is too high, the impact strength decreases, the gel time becomes faster, the post-curing time is shortened, and the exothermic peak is high, resulting in rapid heat release during the production of crafts, deformation or cracking, or even cracking. High exothermic peak and rapid heat release will also cause the shrinkage rate to increase, affecting the product effect.

[0013] Preferably, the weight ratio of maleic anhydride to phthalic anhydride is 0.47-0.51:1, which can avoid the curing delay caused by low proportion or the rapid curing caused by high proportion, and improve the physical properties and structural stability.

[0014] Maleic anhydride contains double bonds, increasing the crosslinking density of the resin to improve hardness, but excessive amounts will increase the brittleness of the resin; the benzene ring structure of phthalic anhydride enhances heat resistance and rigidity, simulating the luster of jade. The ratio of the two within the range of 0.46-0.52:1 ensures that the resin has both jade texture and can withstand mechanical stress during processing.

[0015] The antioxidant is triphenyl phosphite; triphenyl phosphite can block the oxidation chain reaction by decomposing hydroperoxide, and can reduce the yellowing phenomenon of high molecular materials caused by aging. The polymerization inhibitor is hydroquinone, p-benzoquinone, methyl hydroquinone, tert-butyl hydroquinone or tert-butyl catechol. Phenolic polymerization inhibitors can capture free radicals through benzene ring structure to block chain polymerization; all polymerization inhibitors are compatible with unsaturated resin, and the unreacted residues will not interfere with the transparency and mechanical properties of the imitation jade product, meeting the requirements of the surface gloss of the handicraft. P-benzoquinone can effectively delay resin self-polymerization by capturing free radicals, and has antioxidant function, which can inhibit the yellowing of the product. The tert-butyl hydroquinone has high steric hindrance effect after introducing tert-butyl group, which improves the thermal stability; the methyl group in methyl hydroquinone enhances the solubility of the molecule, and the compatibility with the resin system is better, which is suitable for complex formula requirements. P-benzoquinone can still maintain stable polymerization inhibition activity in high temperature environment, and is especially suitable for imitation jade resin process which needs to be cured by heating. P-benzoquinone can inhibit early polymerization, and tert-butyl hydroquinone can delay late gelation.

[0016] The stabilizer is copper isooctoate or copper naphthenate; the molecular structure of the stabilizer is stable, the thermal stability is high, the compatibility with the resin system is good, and the residues have no effect on the transparency. The stabilizer has corrosion prevention function, and is suitable for scenes which need long-term corrosion resistance.

[0017] The weight ratio of the copper isooctoate and the copper naphthenate is 1.5-4:1; the copper isooctoate and the copper naphthenate can play a synergistic effect in the weight ratio of 1.5-4:1, and the principle is mainly based on the molecular structure complementarity and the oxidation-reduction synergistic mechanism. The copper isooctoate can improve the dispersibility of the copper naphthenate; preferably, the weight ratio of the copper isooctoate and the copper naphthenate is 3:1, which realizes more stable heat release in the curing process, and makes the mechanical properties and the gloss reach the best.

[0018] The paraffin is 52# paraffin or 54# paraffin; the paraffin has high purity, high chemical inertness, strong process applicability and small volume shrinkage.

[0019] The diluent is styrene or methyl styrene; the styrene can effectively reduce the viscosity of the resin and improve the wettability of the filler; as a traditional diluent, the styrene is low in price and high in copolymerization activity with unsaturated polyester, can quickly initiate the curing reaction at room temperature, and shorten the production cycle of handicrafts. The methyl styrene has lower volatile organic content, reduces the release of irritating gas in the processing process, and meets the environmental protection trend of benzene-free resin. The methyl substituent enhances the thermal stability of the molecule, and can reduce the generation of bubbles in the high temperature curing process, and is especially suitable for high transparency imitation jade products which need to be formed by heating. The styrene reduces the viscosity, the methyl styrene delays the gelation, and the balance of viscosity and reactivity can be realized when the two are mixed.

[0020] The ultraviolet absorber is 2-(2'-hydroxy-5'-tert-octylphenyl) benzotriazole or 2-(2'-hydroxy-3,5'-di-tert-pentylphenyl) benzotriazole. 2-(2'-hydroxy-5'-tert-octylphenyl) benzotriazole can absorb ultraviolet light in the 270-340 nm waveband, especially for long-wave ultraviolet light protection, and convert ultraviolet energy into heat energy through intramolecular hydrogen bonds to reduce resin photodegradation, disperse uniformly in various polymers, and have little effect on resin transparency, and is suitable for transparent or light-colored products. The double substituent of 2-(2'-hydroxy-3,5'-di-tert-pentylphenyl) benzotriazole enhances the absorption efficiency, and the double tert-pentyl group at the ortho position of the hydroxyl group can improve the molecular steric hindrance and enhance the absorption capacity of short-wave ultraviolet light, and is suitable for more severe ultraviolet exposure environments.

[0021] The whitening agent is 2,5-bis(5-tert-butyl-2-benzoxazolyl) thiophene; the bis-benzoxazolyl group significantly improves the fluorescence emission efficiency through the conjugation effect, so that the imitation jade resin presents a luster closer to natural jade; the 5-tert-butyl substituent effectively inhibits molecular thermal motion, reduces the risk of side reactions with free radicals or oxidation products in the resin system, and still maintains whitening stability in a ≥120°C curing process. The whitening agent can absorb ultraviolet light emitted during the aging process of the resin, emit blue light, and reduce the yellowing phenomenon after long-term exposure of the product. The molecular structure of the whitening agent is polar and matches the diluent styrene, reducing the migration tendency, and the hydrophobic effect of the tert-butyl group makes the migration rate of the whitening agent in the styrene dilution system low.

[0022] The weight ratio of the ultraviolet absorber to the whitening agent is 8.75-14.0:1, and within this ratio range, the synergistic effect of the two mainly manifests as: optimizing gloss, balancing curing and mechanical properties, and improving weather resistance. The whitening agent improves the initial gloss of the resin by scattering ultraviolet and visible light, and the ultraviolet absorber inhibits photodegradation by absorbing high-energy ultraviolet light. The ultraviolet absorber in the range of 0.03-0.035 parts does not significantly interfere with the curing reaction, and the whitening agent does not affect the crosslinking density of the resin. The synergistic effect of the two can maintain the gloss retention rate after irradiation and inhibit color change caused by molecular chain rupture, prolonging the service life.

[0023] When the ratio of the two exceeds the above range, the synergistic effect is destroyed, the curing efficiency and reaction activity are unbalanced, the mechanical properties and optical stability conflict, and when the ultraviolet absorber is excessive, its heat absorption characteristics interfere with the exothermic curing; when the ultraviolet absorber is insufficient, it accelerates the oxidation of the surface layer and increases the color difference. When the whitening agent is excessive, it causes abnormal internal refractive index of the resin, leading to micro-fluorescence; when the whitening agent is insufficient, it aggravates uneven light scattering, leading to increased color difference.

[0024] According to another aspect of the present application, there is also provided a method for preparing the unsaturated polyester resin for jade-imitating handicrafts, comprising the following steps:

[0025] (1) adding diethylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride and an antioxidant into a reactor according to weight parts, heating to 155-165℃, then keeping the temperature for 0.5-1.0 h, and then continuously heating to 200-210℃;

[0026] (2) reacting at 200-210℃ for 2-3 h, and then dehydrating when the acid value reaches 50-55 mgKOH / g;

[0027] (3) adding a polymerization inhibitor and paraffin according to weight parts after cooling, then adding a stabilizer and a diluent according to weight parts after further cooling, and then adding a UV absorber and a whitening agent according to weight parts after further cooling, and mixing uniformly to obtain the unsaturated polyester resin for jade-imitating handicrafts.

[0028] In step (1), the heating rate for continuously heating to 200-210℃ is 12-14℃ / h. The heating rate of 12-14℃ / h for heating to 200-210℃ prevents local overheating from causing maleic anhydride isomerization failure, and avoids sudden cooling from causing resin phase separation or component segregation.

[0029] In step (2), the reaction is carried out at 200-210℃ for 2-3 h, and then dehydrating at 200-210℃ until the acid value reaches 20-25 mgKOH / g. The dehydration removes the water generated in the reaction, promotes the reaction to proceed in the direction of polyester chain growth, reduces the acid value from 50-55 mgKOH / g to 20-25 mgKOH / g, improves the esterification rate, and improves the water resistance by reducing the hydrophilic carboxyl group while retaining sufficient crosslinking sites.

[0030] In step (3), the specific operation is adding a polymerization inhibitor and paraffin according to weight parts after cooling, then adding a stabilizer and a diluent according to weight parts after further cooling, and then adding a UV absorber and a whitening agent according to weight parts after further cooling, and mixing uniformly to obtain the unsaturated polyester resin for jade-imitating handicrafts.

[0031] The polymerization inhibitor needs to be quickly dispersed in a molten state at 170-190℃ to ensure that it is in full contact with the polyester molecular chain to form an effective free radical capture network. Paraffin is in a liquid state at high temperatures, and the paraffin liquid covers the surface of the resin to inhibit premature gelation. Adding a diluent according to weight parts at 90-110℃ can reduce volatilization while avoiding premature decomposition of the stabilizer. Adding a UV absorber according to weight parts at 50-60℃ can maintain the stability of its UV absorption peak. The whitening agent will undergo esterification side reactions with residual anhydride at high temperatures, and a low-temperature environment can control its degradation rate.

[0032] If it is once cooled to 50-60 DEG C, while adding the polymerization inhibitor, paraffin, stabilizer, diluent, ultraviolet absorber and whitening agent by weight parts, at this time the reaction kettle polyester viscosity is big, the dispersion of polymerization inhibitor is not uniform, leading to the addition of diluent after the appearance of gel, and 50-60 DEG C paraffin solidification leads to uneven dispersion, the addition amount of ultraviolet absorber and whitening agent is less, the wall hanging will affect the adding effect.

[0033] According to another aspect of the present application, the present application also provides the application of the above unsaturated polyester resin or the unsaturated polyester resin prepared by the above method in jade imitation handicraft. The preparation method of the jade imitation handicraft is as follows: the resin and aluminum hydroxide powder in each example and the comparative example are uniformly mixed, a special promoter cobalt isooctanoate for handicraft and a special curing agent methyl ethyl ketone peroxide are added, and then the mixture is uniformly stirred and poured into a mold, the mold is placed in a constant temperature and humidity box, and the cast body obtained after demolding is the jade imitation handicraft. Optionally, the resin and aluminum hydroxide powder are uniformly mixed at a weight ratio of 1:1.3-1.7, and further preferably, the resin and aluminum hydroxide powder are uniformly mixed at a weight ratio of 1:1.5.

[0034] Compared with the prior art, the present application has the beneficial effects that:

[0035] 1. In the present application, the ratio of propylene glycol, methyl propylene glycol and diethylene glycol is optimized, the appropriate ratio of phthalic anhydride and maleic anhydride is used, the reaction is carried out until the acid value reaches 20-25 mgKOH / g, and the viscosity and curing time of the resin finished product are beneficial to handicraft production and processing. After the addition of fillers, the resin is uniformly distributed, the heat release is slow and uniform, cracks or cracks are avoided during the curing of the product, and the appropriate shrinkage rate is beneficial to demolding without affecting the product effect. Through the synergistic control of molecular structure optimization and process parameters, the present application realizes the comprehensive breakthrough of the resin in processing adaptability, mechanical strength and appearance quality. The present application is water white, and the hardness, tensile strength, elongation at break, bending strength and impact strength can meet the requirements of handicraft. The toughness is related to the tensile strength and elongation at break.

[0036] 2. In the present application, the copper isooctanoate and copper naphthenate are used in a weight ratio of 1.5-4:1 to play a synergistic effect, the heat release during the curing process is stable, and the mechanical properties and gloss are improved.

[0037] 3. The synergistic optimization of the ultraviolet absorber and the whitening agent optimizes the gloss, balances the curing and mechanical properties, and makes the handicraft after processing and molding have excellent gloss, color and physical properties remain stable, and still maintain good gloss after long time illumination, and improve the weather resistance. DETAILED DESCRIPTION

[0038] Example 9 is the best embodiment of the present application, and the present application will be further described in combination with specific examples and comparative examples.

[0039] The chemical auxiliaries used in the examples and comparative examples of the present application are all commercially available, and the specific information is as follows:

[0040] Diethylene glycol: industrial grade, purchased from Ningbo Hongyixin Import & Export Co., Ltd.;

[0041] Methyl propylene glycol: industrial grade, purchased from Nanjing Dezhe Chemical Co., Ltd.;

[0042] Propylene glycol: industrial grade, purchased from Guangdong Hongjun New Material Co., Ltd.;

[0043] Maleic anhydride: industrial grade, purchased from Shandong Dechuan New Material Co., Ltd.;

[0044] Phthalic anhydride: industrial grade, purchased from Hubei Nengtai Science and Technology Co., Ltd.;

[0045] Triphenyl phosphite: industrial grade, purchased from Changhe Chemical New Material (Jiangsu) Co., Ltd.;

[0046] p-Dihydroxybenzene: industrial grade, purchased from Changzhou Yurong Chemical Co., Ltd.;

[0047] p-Benzoquinone: industrial grade, purchased from Jinan Xichuan Chemical Technology Co., Ltd.;

[0048] Methyl p-dihydroxybenzene: industrial grade, purchased from Wuxi Qianfeng Chemical Technology Co., Ltd.;

[0049] 4-tert-Butyl p-dihydroxybenzene: industrial grade, purchased from Changzhou Yurong Chemical Co., Ltd.;

[0050] 52# paraffin wax: industrial grade, purchased from Jingmen Weijia Industry Co., Ltd.;

[0051] 54# paraffin wax: industrial grade, purchased from Jingmen Weijia Industry Co., Ltd.;

[0052] Cobalt isooctoate: industrial grade, purchased from Shanghai Pudong Tongzhu Chemical Co., Ltd.;

[0053] Copper naphthenate: industrial grade, purchased from Shanghai Pudong Tongzhu Chemical Co., Ltd.;

[0054] Styrene: industrial grade, purchased from Zhangjiagang Free Trade Zone Aolide International Business & Trade Co., Ltd.;

[0055] Methylstyrene: industrial grade, purchased from Shandong Jinghao Chemical Co., Ltd.;

[0056] 2-(2'-hydroxy-5'-tert-octylphenyl) benzotriazole: industrial grade, purchased from Changzhou Yurong Chemical Co., Ltd.;

[0057] 2-(2'-hydroxy-3,5'-di-tert-pentylphenyl) benzotriazole: industrial grade, purchased from Changzhou Yurong Chemical Co., Ltd.;

[0058] 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene: industrial grade, purchased from Changzhou Yurong Chemical Co., Ltd.;

[0059] Cobalt isooctoate: industrial grade, purchased from Shanghai Taoyuan Cobalt Co., Ltd.;

[0060] Methyl ethyl ketone peroxide: CAS No. 131-11-3, purchased from Tianjin Nu Liang Peroxide Co., Ltd.;

[0061] Constant temperature and humidity incubator: Shaoxing Boxi Instrument and Equipment Co., Ltd.

[0062] Example 1

[0063] The formula of the unsaturated polyester resin for imitation jade handicraft in this embodiment is composed of the following components:

[0064] Dipropylene glycol 16.8 parts, methyl propylene glycol 6.6 parts, propylene glycol 6.6 parts, maleic anhydride 12 parts, phthalic anhydride 25.53 parts, triphenyl phosphite 0.052 parts, hydroquinone 0.0043 parts, 52# paraffin wax 0.058 parts, copper isooctoate 0.0012 parts, styrene 32.321 parts, 2-(2'-hydroxy-5'-tert-octylphenyl) benzotriazole 0.03 parts, 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene 0.0035 parts; the weight ratio of propylene glycol to methyl propylene glycol is 1:1, methyl propylene glycol accounts for 22% of the total amount of diols; the weight ratio of maleic anhydride to phthalic anhydride is 0.47:1;

[0065] The preparation method of this embodiment includes the following steps:

[0066] (1) Dipropylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride and triphenyl phosphite are added to the reactor according to the weight parts, heated to 155°C, then kept for 0.5h, and then continuously heated to 200°C;

[0067] (2) Under the condition of 200°C, react for 2h when the acid value reaches 50mgKOH / g; dehydrate under the condition of 200°C until the acid value reaches 20mgKOH / g;

[0068] (3) Cool to 170°C and add the polymerization inhibitor and paraffin wax according to the weight parts; then cool to 90°C and add the stabilizer and diluent according to the weight parts; continue to cool to 50°C and add the ultraviolet absorber and whitening agent according to the weight parts, mix well; obtain the unsaturated polyester resin for imitation jade handicraft.

[0069] Example 2

[0070] The formula of the unsaturated polyester resin for imitation jade handicrafts of the present embodiment is composed of the following components:

[0071] Dipropylene glycol 16.2 parts, methyl propylene glycol 6 parts, propylene glycol 7.8 parts, maleic anhydride 12 parts, phthalic anhydride 25.53 parts, triphenyl phosphite 0.058 parts, p-benzoquinone 0.0038 parts, 54# paraffin wax 0.052 parts, copper naphthenate 0.0009 parts, methyl styrene 32.3178 parts, 2- (2'-hydroxy-3, 5'-di-tert-pentyl phenyl) benzotriazole 0.035 parts, 2, 5-bis (5-tert-butyl-2-benzoxazolyl) thiofuran 0.0025 parts; the weight ratio of propylene glycol to methyl propylene glycol is 1.3:1, and the methyl propylene glycol accounts for 20% of the total amount of diols; the weight ratio of maleic anhydride to phthalic anhydride is 0.47:1;

[0072] The preparation method of the present embodiment includes the following steps:

[0073] (1) Dipropylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride and triphenyl phosphite are added to the reactor according to the weight parts, heated to 165℃, and then kept at this temperature for 1.0h, and then continuously heated to 210℃;

[0074] (2) Under the condition of 210℃, react for 3h when the acid value reaches 55mgKOH / g; dehydrate under the condition of 210℃ until the acid value reaches 25mgKOH / g;

[0075] (3) Cool down to 190℃ and add the polymerization inhibitor and paraffin wax according to the weight parts; then cool down to 110℃ and add the stabilizer and diluent according to the weight parts; continue to cool down to 60℃ and add the ultraviolet absorber and whitening agent according to the weight parts, and mix well; to obtain the unsaturated polyester resin for imitation jade handicrafts.

[0076] Example 3

[0077] The formula of the unsaturated polyester resin for imitation jade handicrafts of the present embodiment is composed of the following components:

[0078] Dipropylene glycol 16.8 parts, methyl propylene glycol 6.6 parts, propylene glycol 6.6 parts, maleic anhydride 11.73 parts, phthalic anhydride 25.5 parts, triphenyl phosphite 0.052 parts, methyl hydroquinone 0.0038 parts, 52# paraffin wax 0.058 parts, copper isooctanoate 0.0012 parts, styrene 32.6215 parts, 2- (2'-hydroxy-5'-tert-octyl phenyl) benzotriazole 0.03 parts, 2, 5-bis (5-tert-butyl-2-benzoxazolyl) thiofuran 0.0035 parts; the weight ratio of diol to methyl propylene glycol is 1:1, and the methyl propylene glycol accounts for 22% of the total amount of diols; the weight ratio of maleic anhydride to phthalic anhydride is about 0.46:1;

[0079] The preparation method of the embodiment comprises the following steps:

[0080] (1) Put diethylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride and triphenyl phosphite into the reactor according to the weight parts, heat to 160℃, then keep the temperature for 0.8h, and then continue to heat to 205℃;

[0081] (2) Under the condition of 205℃, react for 2.5h, when the acid value reaches 53mgKOH / g, dehydrate under the condition of 205℃ until the acid value reaches 23mgKOH / g;

[0082] (3) Cool to 180℃, add the polymerization inhibitor and paraffin according to the weight parts; cool to 100℃, add the stabilizer and diluent according to the weight parts; continue to cool to 55℃, add the ultraviolet absorber and whitening agent according to the weight parts; mix well to obtain the unsaturated polyester resin for imitation jade handicrafts.

[0083] Embodiment 4

[0084] The formula of the unsaturated polyester resin for imitation jade handicrafts of the embodiment is composed of the following components:

[0085] Diethylene glycol 16.2 parts, methyl propylene glycol 6 parts, propylene glycol 7.8 parts, maleic anhydride 12 parts, phthalic anhydride 25.53 parts, triphenyl phosphite 0.058 parts, t-butyl hydroquinone 0.0043 parts, 54# paraffin 0.052 parts, copper isooctanoate 0.0009 parts, styrene 32.3173 parts, 2- (2'-hydroxy-5'-tert-octylphenyl) benzotriazole 0.035 parts, 2, 5-bis (5-tert-butyl-2-benzoxazolyl) thiophene 0.0025 parts; the weight ratio of propylene glycol to methyl propylene glycol is 1.3:1, and the methyl propylene glycol accounts for about 20% of the total amount of diols; the weight ratio of maleic anhydride to phthalic anhydride is about 0.47:1;

[0086] The preparation method of the embodiment comprises the following steps:

[0087] (1) Put diethylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride and triphenyl phosphite into the reactor according to the weight parts, heat to 160℃, then keep the temperature for 0.8h, and then continue to heat to 205℃;

[0088] (2) Under the condition of 205℃, react for 2.5h, when the acid value reaches 53mgKOH / g; dehydrate under the condition of 205℃ until the acid value reaches 23mgKOH / g;

[0089] (3) cooling, adding polymerization inhibitor and paraffin by weight parts; cooling again, adding stabilizer and diluent by weight parts; continue to cool, adding ultraviolet absorber and whitening agent by weight parts, mix well; get imitation jade handicraft unsaturated polyester resin.

[0090] Example 5

[0091] The formula of the imitation jade handicraft unsaturated polyester resin of the embodiment comprises the following components:

[0092] Dipropylene glycol 16.8 parts, methyl propylene glycol 6.6 parts, propylene glycol 6.6 parts, maleic anhydride 12.8 parts, phthalic anhydride 25.09 parts, triphenyl phosphite 0.058 parts, tert-butyl catechol 0.0043 parts, 52# paraffin 0.052 parts, copper isooctanoate 0.0009 parts, methylstyrene 31.9573 parts, 2- (2'-hydroxy-5'-tert-octyl phenyl) benzotriazole 0.035 parts, 2, 5-bis (5-tert-butyl-2-benzoxazolyl) thiofuran 0.0025 parts; the weight ratio of propylene glycol to methyl propylene glycol is 1:1, and the methyl propylene glycol accounts for 22% of the total amount of dihydric alcohol; the weight ratio of maleic anhydride to phthalic anhydride is about 0.51:1;

[0093] The preparation method of the embodiment comprises the following steps:

[0094] (1) Dipropylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride and triphenyl phosphite are added into the reactor by weight parts, heated to 160℃, then kept for 0.8h, and then heated to 205℃;

[0095] (2) Under the condition of 205℃, react for 2.5h when the acid value reaches 53mgKOH / g; dehydrate under the condition of 205℃ until the acid value is 23mgKOH / g;

[0096] (3) Cooling to 180℃, adding polymerization inhibitor and paraffin by weight parts; cooling again, adding stabilizer and diluent by weight parts; continue to cool, adding ultraviolet absorber and whitening agent by weight parts, mix well; get imitation jade handicraft unsaturated polyester resin.

[0097] Example 6

[0098] The formula of the imitation jade handicraft unsaturated polyester resin of the embodiment comprises the following components:

[0099] Diethylene glycol 16.2 parts, methyl propylene glycol 6 parts, propylene glycol 7.8 parts, maleic anhydride 13 parts, phthalic anhydride 25 parts, triphenyl phosphite 0.058 parts, t-butyl hydroquinone 0.0038 parts, 54# paraffin wax 0.058 parts, copper isooctoate 0.0009 parts, methyl styrene 31.8418 parts, 2-(2'-hydroxy-5'-t-octylphenyl) benzotriazole 0.035 parts, 2,5-bis(5-t-butyl-2-benzoxazolyl) thiophene 0.0025 parts; the weight ratio of propylene glycol to methyl propylene glycol is 1.3:1, and the methyl propylene glycol accounts for about 20% of the total dihydric alcohol; the weight ratio of maleic anhydride to phthalic anhydride is 0.52:1;

[0100] The preparation method of the embodiment comprises the following steps:

[0101] (1) Diethylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride and triphenyl phosphite are put into a reactor, and after being heated to 160°C, the temperature is kept for 0.8 h, and then the temperature is continuously increased to 205°C;

[0102] (2) The reaction is carried out at 205°C for 2.5 h when the acid value reaches 53 mgKOH / g; dehydration is carried out at 205°C until the acid value reaches 23 mgKOH / g;

[0103] (3) The temperature is decreased to 180°C, and the polymerization inhibitor and paraffin wax are added by weight parts; then the temperature is decreased to 100°C, and the stabilizer and diluent are added by weight parts; then the temperature is continuously decreased to 55°C, and the ultraviolet absorber and whitening agent are added by weight parts, and then they are uniformly mixed; thus an unsaturated polyester resin for imitation jade handicrafts is obtained.

[0104] Example 7

[0105] The formula of the unsaturated polyester resin for imitation jade handicrafts of the embodiment is composed of the following components:

[0106] Diethylene glycol 16.8 parts, methyl propylene glycol 6.6 parts, propylene glycol 6.6 parts, maleic anhydride 12.8 parts, phthalic anhydride 25.09 parts, triphenyl phosphite 0.052 parts, hydroquinone 0.0038 parts, 52# paraffin wax 0.058 parts, copper isooctoate 0.0012 parts, methyl styrene 31.9615 parts, 2-(2'-hydroxy-5'-t-octylphenyl) benzotriazole 0.03 parts, 2,5-bis(5-t-butyl-2-benzoxazolyl) thiophene 0.0035 parts; the weight ratio of propylene glycol to methyl propylene glycol is 1:1, and the methyl propylene glycol accounts for 22% of the total dihydric alcohol; the weight ratio of maleic anhydride to phthalic anhydride is about 0.51:1;

[0107] The preparation method of the embodiment comprises the following steps:

[0108] (1) Add diethylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride and triphenyl phosphite into the reactor according to the weight parts, heat to 160℃ for 0.8h, then heat to 205℃;

[0109] (2) React at 205℃ for 2.5h until the acid value reaches 53mgKOH / g, then dehydrate at 205℃ until the acid value reaches 23mgKOH / g;

[0110] (3) Cool to 180℃, add the polymerization inhibitor and paraffin according to the weight parts; then cool to 100℃, add the stabilizer and diluent according to the weight parts; continue to cool to 55℃, add the ultraviolet absorber and whitening agent according to the weight parts, mix well; obtain the unsaturated polyester resin for imitation jade handicrafts.

[0111] Example 8

[0112] The formula of the unsaturated polyester resin for imitation jade handicrafts of this example is composed of the following components:

[0113] diethylene glycol 16.2 parts, methyl propylene glycol 6 parts, propylene glycol 7.8 parts, maleic anhydride 12.8 parts, phthalic anhydride 25.09 parts, triphenyl phosphite 0.052 parts, hydroquinone 0.0043 parts, 52# paraffin 0.052 parts, copper isooctoate 0.0012 parts, styrene 31.967 parts, 2-(2'-hydroxy-5'-tert-octylphenyl) benzotriazole 0.03 parts, 2,5-bis(5-tert-butyl-2-benzoxazolyl) thiophene 0.0035 parts; the weight ratio of propylene glycol to methyl propylene glycol is 1.3:1, and the methyl propylene glycol accounts for 20% of the total amount of diols; the weight ratio of maleic anhydride to phthalic anhydride is about 0.51:1;

[0114] The preparation method of this example includes the following steps:

[0115] (1) Add diethylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride and triphenyl phosphite into the reactor, heat to 160℃, keep for 0.8h, then continue to heat to 205℃;

[0116] (2) React at 205℃ for 2.5h until the acid value reaches 53mgKOH / g, then dehydrate at 205℃ until the acid value reaches 23mgKOH / g;

[0117] (3) Cool to 180℃, add the polymerization inhibitor and paraffin according to the weight parts; then cool to 100℃, add the stabilizer and diluent according to the weight parts; continue to cool to 55℃, add the ultraviolet absorber and whitening agent according to the weight parts, mix well; obtain the unsaturated polyester resin for imitation jade handicrafts.

[0118] Example 9

[0119] The formula of the unsaturated polyester resin for imitation jade handicrafts of the present embodiment is composed of the following components:

[0120] Dipropylene glycol 16.5 parts, methyl propylene glycol 6.3 parts, propylene glycol 7.2 parts, maleic anhydride 12.4 parts, phthalic anhydride 25.3 parts, triphenyl phosphite 0.055 parts, hydroquinone 0.004 parts, 54# paraffin wax 0.055 parts, copper isooctoate 0.00075 parts, copper naphthenate 0.00025, methyl styrene 32.15 parts, 2-(2'-hydroxy-5'-tert-octyl phenyl) benzotriazole 0.032 parts, 2,5-bis(5-tert-butyl-2-benzoxazolyl) thiophene 0.003 parts; the weight ratio of propylene glycol to methyl propylene glycol is 1.14:1, and the methyl propylene glycol accounts for 21% of the total amount of diols; the weight ratio of maleic anhydride to phthalic anhydride is about 0.49:1;

[0121] The preparation method of the present embodiment comprises the following steps:

[0122] (1) Dipropylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride and triphenyl phosphite are put into a reactor, heated to 160°C, and kept for 0.8h, then heated to 205°C;

[0123] (2) React at 205°C for 2.5h, when the acid value reaches 53mgKOH / g, dehydrate at 205°C until the acid value reaches 23mgKOH / g;

[0124] (3) Cool to 180°C, add the polymerization inhibitor and paraffin wax according to the weight parts; then cool to 100°C, add the stabilizer and diluent according to the weight parts; continue to cool to 55°C, add the ultraviolet absorber and whitening agent according to the weight parts, and mix well; to obtain the unsaturated polyester resin for imitation jade handicrafts.

[0125] Comparative Example 1

[0126] The preparation method of the unsaturated polyester resin for imitation jade handicrafts of the present comparative example is the same as that of Example 9, except that in step (3), the whitening agent and the ultraviolet absorber are not added according to the weight parts.

[0127] Comparative Example 2

[0128] The preparation method of the unsaturated polyester resin for imitation jade handicrafts of the present comparative example is the same as that of Example 9, except that in step (3), the ultraviolet absorber is added according to the weight parts of 0.032 parts, and the whitening agent is not added according to the weight parts.

[0129] Comparative Example 3

[0130] The preparation method of the unsaturated polyester resin for imitation jade handicrafts in this comparative example is the same as that of Example 9, except that in step (3), 0.003 parts by weight of a whitening agent is added, and no ultraviolet absorber is added.

[0131] Comparative Example 4

[0132] The preparation method of the unsaturated polyester resin for imitation jade handicrafts in this comparative example is the same as that of Example 9, except that in step (3), 0.0036 parts by weight of a whitening agent and 0.029 parts by weight of an ultraviolet absorber are added.

[0133] Comparative Example 5

[0134] The preparation method of the unsaturated polyester resin for imitation jade handicrafts in this comparative example is the same as that of Example 9, except that in step (3), 0.0024 parts by weight of a whitening agent and 0.036 parts by weight of an ultraviolet absorber are added.

[0135] Comparative Example 6

[0136] The preparation method of the unsaturated polyester resin for imitation jade handicrafts in this comparative example is the same as that of Example 9, except that in step (1), no methyl propylene glycol is added.

[0137] Comparative Example 7

[0138] The preparation method of the unsaturated polyester resin for imitation jade handicrafts in this comparative example is the same as that of Example 9, except that in step (1), no propylene glycol is added.

[0139] Comparative Example 8

[0140] The preparation method of the unsaturated polyester resin for imitation jade handicrafts in this comparative example is the same as that of Example 9, except that in step (3), 0.00082 parts of copper isooctoate and 0.00018 parts of copper naphthenate are added.

[0141] Comparative Example 9

[0142] The preparation method of the unsaturated polyester resin for imitation jade handicrafts in this comparative example is the same as that of Example 9, except that in step (3), 0.00055 parts of copper isooctoate and 0.00055 parts of copper naphthenate are added.

[0143] Comparative Example 10

[0144] The preparation method of the unsaturated polyester resin for imitation jade handicrafts in this comparative example is the same as that of Example 9, except that in step (1), the weight ratio of propylene glycol to methyl propylene glycol is 0.5.

[0145] Comparative Example 11

[0146] The preparation method of the unsaturated polyester resin for jade-imitation handicrafts in this comparative example is the same as that in Example 9, except that the weight ratio of propylene glycol to methyl propylene glycol in step (1) is 0.6.

[0147] Comparative Example 12

[0148] The preparation method of the unsaturated polyester resin for jade-imitation handicrafts in this comparative example is the same as that in Example 9, except that the weight ratio of propylene glycol to methyl propylene glycol in step (1) is 0.7.

[0149] Comparative Example 13

[0150] The preparation method of the unsaturated polyester resin for jade-imitation handicrafts in this comparative example is the same as that in Example 9, except that the weight ratio of propylene glycol to methyl propylene glycol in step (1) is 0.8.

[0151] Comparative Example 14

[0152] The preparation method of the unsaturated polyester resin for jade-imitation handicrafts in this comparative example is the same as that in Example 9, except that the weight ratio of propylene glycol to methyl propylene glycol in step (1) is 0.9.

[0153] Comparative Example 15

[0154] The preparation method of the unsaturated polyester resin for jade-imitation handicrafts in this comparative example is the same as that in Example 9, except that the weight ratio of propylene glycol to methyl propylene glycol in step (1) is 0.95.

[0155] Comparative Example 16

[0156] The preparation method of the unsaturated polyester resin for jade-imitation handicrafts in this comparative example is the same as that in Example 9, except that the weight ratio of propylene glycol to methyl propylene glycol in step (1) is 1.1.

[0157] Comparative Example 17

[0158] The preparation method of the unsaturated polyester resin for jade-imitation handicrafts in this comparative example is the same as that in Example 9, except that the weight ratio of propylene glycol to methyl propylene glycol in step (1) is 1.2.

[0159] Comparative Example 18

[0160] The preparation method of the unsaturated polyester resin for jade-imitation handicrafts in this comparative example is the same as that in Example 9, except that the weight ratio of propylene glycol to methyl propylene glycol in step (1) is 1.35.

[0161] Comparative Example 19

[0162] The preparation method of the unsaturated polyester resin for imitation jade handicrafts in this comparative example is the same as that in Example 9, except that the weight ratio of propylene glycol to methyl propylene glycol in step (1) is 1.4.

[0163] Comparative Example 20

[0164] The preparation method of the unsaturated polyester resin for imitation jade handicrafts in this comparative example is the same as that in Example 9, except that the weight ratio of propylene glycol to methyl propylene glycol in step (1) is 1.5.

[0165] Performance test

[0166] The performance of the examples and comparative examples was tested, and the specific test results are shown in Tables 1, 2, 3 and 4.

[0167] The liquid index of the unsaturated polyester resin prepared in Examples 1-9 and Comparative Examples 1-9 was tested, and the specific test results are shown in Table 1.

[0168] The performance of the cast products of the unsaturated polyester resin prepared in Examples 1-9 and Comparative Examples 1-9 was tested, and the specific test results are shown in Table 2.

[0169] The cooling acid value refers to the time when the target acid value is reached and the cooling is started, which represents the reaction endpoint at this time. In Example 9, the other conditions remain unchanged, and different cooling acid values represent different reaction degrees. The lower the acid value, the higher the reaction degree. Different cooling acid values were used for synthesis, and viscosity, exothermic peak, oil absorption value and handicraft color difference were tested. The specific test results are shown in Table 3.

[0170] Based on the formulation of Example 9, the weight ratio of propylene glycol to methyl propylene glycol was adjusted, i.e. Comparative Examples 10-20, and viscosity, exothermic peak, oil absorption value and handicraft color difference were tested. The specific test results are shown in Table 4.

[0171] The tensile strength of the unsaturated polyester resin for imitation jade handicrafts was tested according to GB / T2567-2021;

[0172] The tensile elastic modulus of the unsaturated polyester resin for imitation jade handicrafts was tested according to GB / T2567-2021;

[0173] The elongation at break of the unsaturated polyester resin for imitation jade handicrafts was tested according to GB / T2567-2021;

[0174] The bending strength of the unsaturated polyester resin for imitation jade handicrafts was tested according to GB / T2567-2021;

[0175] The bending elastic modulus of the unsaturated polyester resin for imitation jade handicrafts was tested according to GB / T2567-2021;

[0176] The impact strength of the unsaturated polyester resin for imitation jade handicraft is tested according to GB / T2567-2021.

[0177] The barcol hardness of the unsaturated polyester resin for imitation jade handicraft is tested according to GB / T3854-2017.

[0178] The heat distortion temperature of the unsaturated polyester resin for imitation jade handicraft is tested according to GB / T1643-2019.

[0179] The viscosity of the unsaturated polyester resin for imitation jade handicraft is tested according to GB / T7193-2008.

[0180] The gel time of the unsaturated polyester resin for imitation jade handicraft is tested according to GB / T7193-2008.

[0181] The exothermic peak of the unsaturated polyester resin for imitation jade handicraft is tested according to GB / T7193-2008.

[0182] The oil absorption value of the unsaturated polyester resin for imitation jade handicraft is tested according to GB / T7193-2008.

[0183] Post-curing time: The gel time of the unsaturated polyester resin for imitation jade handicraft is tested according to GB / T7193-2008. The post-curing time refers to the time interval from the gel state, when the material is jelly-like and the texture is soft, to the temperature reaching the exothermic peak and maintaining a stable temperature for 30 seconds. During this process, the resin completes the transition from gel state to complete curing and finally presents a high hardness state.

[0184] Oil absorption value test: The oil absorption value of the unsaturated polyester resin for imitation jade handicraft is the absorption amount of the resin, which is an index of the absorption amount of the filler to the resin. The oil absorption value rises, and the viscosity of the resin rises accordingly, which seriously affects the dispersibility and rheological properties, making the molding process performance worse. When the same viscosity is obtained, more resin needs to be added, which increases the cost. The same proportion of filler is added to each example and comparative example, the same speed is selected using the American BROOKFIELD DV2T viscometer, and the oil absorption value viscosity of the test sample is tested at the same temperature.

[0185] Color difference test: Gloss reflects the comprehensive performance of the smoothness, cleanliness and mirror reflection ability of the surface of an object. The higher the gloss, the brighter the surface color and the more wear-resistant. The universal 60-degree gloss meter WGG-60 of Licheng Technology is used to test the surface gloss of the handicrafts made by the examples and comparative examples. The gloss is compared and tested after the made handicraft samples are irradiated by LED ultraviolet lamp (wavelength 280-400nm) for 168h. The color difference is tested by the LS173 colorimeter of Linshang Technology.

[0186] Color difference ΔΕ * ab The calculation formula is:

[0187] Wherein:

[0188] ΔL * : lightness difference (brightness change);

[0189] Δa * : red-green axis chroma difference;

[0190] Δb * : yellow-blue axis chroma difference;

[0191] Jade process preparation method: the resin and aluminum hydroxide powder in each example and comparative example are mixed and stirred uniformly at a weight ratio of 1:1.5, 0.3 parts of cobalt isooctanoate special for handicrafts and 1.5 parts of peroxide methyl ethyl ketone special for handicrafts are added at room temperature of 25°C and humidity of 50%, and then the mixture is stirred for 1 min, and then poured into a mold. The mold is placed in a constant temperature and humidity incubator to keep the temperature at 30°C and the humidity at 40% for 30 min for constant temperature curing, and then taken out and demolded. The demolded handicraft is placed in a constant temperature and humidity incubator to keep the temperature at 30°C and the humidity at 40% for 1 h for further curing, and then taken out for gloss testing.

[0192] Cooling acid value: the cooling acid value is the acid value at which the reaction is terminated and the temperature is lowered; the different cooling acid values in Example 9 represent different reaction degrees, and the lower the acid value, the higher the reaction degree.

[0193] Oil absorption value viscosity: the viscosity of the resin after adding fillers is tested according to GB / T7193-2008 to obtain the oil absorption value viscosity; at the same testing temperature, the higher the oil absorption value, the lower the adsorption capacity.

[0194] The color of the resin is determined by visual observation.

[0195] Table 1 Performance test results of Examples 1-9 and Comparative Examples 1-9 in liquid state

[0196] .

[0197] Table 2 Resin cast body test results of Examples 1-9 and Comparative Examples 1-9

[0198] .

[0199] Table 3 Comparison results of viscosity, exothermic peak and oil absorption value viscosity of different cooling acid values of Example 9

[0200] .

[0201] ​Table 4 Performance test results of examples and comparative examples

[0202] .

[0203] From Tables 1-3, it can be seen that when the amount of methylpropanediol is 20-22% of the total amount of diols, the comprehensive performance is optimal, the viscosity of Examples 1-9 is 320-350 mPa-s, the gel time is 3'38"-3'55", and the exothermic peak temperature is 156-160°C, indicating that the resin system has excellent process controllability; the water-white appearance and acid value of 19.13-21.38 mgKOH / g indicate that the purity of the raw materials is relatively high; the post-curing time is 9'16-9'45" and the oil absorption value is 2010-2088 cP, indicating that the formulation of Examples 1-9 achieves a balance between curing rate and fluidity, the tensile strength of 60-65 MPa and the bending strength of 106-112 MPa reach the level of engineering plastics, and the combination of impact strength of 12-15 kJ / m² and elongation at break of 4.02-4.95% confirms that the material has both impact resistance and moderate plastic deformation capacity. Among them, Example 9 has the best comprehensive performance, with a tensile strength of 65 MPa, a bending strength of 112 MPa, a tensile elastic modulus of 3188 MPa, and a bending modulus of 3357 MPa.

[0204] The present application solves the contradiction between mechanical strength and weather resistance of traditional resins through molecular structure design and stabilizer compounding. The synergistic curing system controls the exothermic peak temperature to 156-160°C to avoid internal stress accumulation; the ultraviolet absorber transfers light energy through intramolecular hydrogen bonds, reduces the penetration depth of ultraviolet light, and reduces the photodegradation rate; the interface enhancement technology ensures that the filler is fully infiltrated with an oil absorption value of 2010-2088 cP, and improves the interfacial bonding force.

[0205] From Table 3, when the acid value is 15 mgKOH / g, the viscosity increases, leading to poor filler dispersion; the oil absorption value increases, the molecular chain is too long or the crosslinking network is loose; the exothermic peak temperature is too high, leading to stress concentration during curing, causing microcracks.

[0206] When the acid value is 30 mgKOH / g, the viscosity is too low, accompanied by incomplete reaction, resulting in an exothermic peak of only 151°C, insufficient curing crosslinking density, and decreased mechanical properties; the low oil absorption value but insufficient surface density of the cured product limits the weather resistance.

[0207] From Table 3, when the acid value is reduced to 15 mgKOH / g, the viscosity of the resin is too high, and the oil absorption value increases significantly, which will affect the dispersion of the filler; at the same time, the excessive exothermic peak is easy to cause cracks during the curing of the product. When the acid value is 30 mgKOH / g, although the viscosity and oil absorption value are low, the exothermic peak is too low to affect the curing effect. In summary, the best range of acid value is 20-25 mgKOH / g, at which the resin viscosity is moderate, the oil absorption value is reasonable, and the exothermic peak temperature is suitable, which can ensure good processing performance and product quality.

[0208] From Table 1 and Table 2, the gloss retention rate and color difference of Comparative Example 1 are the worst. From the results of Comparative Example 1, the lack of whitening agent will affect the initial gloss of the resin and exacerbate the color difference after light exposure; the lack of ultraviolet absorber will reduce the weather resistance. The gloss of Comparative Example 2 before light exposure is 52.6 GU, which is lower than that of Example 9, which is 73.8 GU; after light exposure, it decreases to 37.5 GU, indicating that the absence of whitening agent leads to a decrease in surface gloss and light resistance of the resin; the absence of whitening agent reduces the ability of the resin to shield ultraviolet rays, accelerating the molecular chain rupture and oxidation reaction caused by light exposure, resulting in a decrease in gloss and an increase in color difference. The gloss of Comparative Example 3 before light exposure is 62.8 GU, and after light exposure, it decreases to 39.8 GU, indicating that the color shift caused by ultraviolet aging is large; the absence of ultraviolet absorber reduces the protective ability of the resin to ultraviolet rays, accelerating the light degradation process. The ultraviolet absorber protects the surface structure of the resin by shielding ultraviolet radiation and delaying molecular chain rupture, and its absence directly leads to a decrease in gloss and an increase in color difference after light exposure.

[0209] In Comparative Example 4, the insufficient amount of ultraviolet absorber and excessive amount of whitening agent lead to a decrease in gloss after light exposure, indicating that the insufficient amount of ultraviolet absorber leads to a decrease in weather resistance and cannot effectively inhibit light degradation; the excessive amount of whitening agent interferes with curing, resulting in a prolonged post-curing time of 10 minutes and 5 seconds; the excessive amount of whitening agent occupies the crosslinking sites, hindering the free radical chain growth reaction; the color difference ΔE*ab reaches 0.99, the excessive amount of whitening agent leads to poor color stability, and the insufficient amount of ultraviolet absorber accelerates the color change after light exposure.

[0210] In Comparative Example 5, excessive UV absorber and insufficient whitening agent hindered the curing reaction, deteriorated mechanical properties, decreased optical stability, increased resin crosslinking network defects, and reduced heat distortion temperature. The prolonged gel time and post-curing time in Comparative Example 5 indicate that excessive UV absorber inhibited the curing reaction activity, leading to reduced crosslinking efficiency; the exothermic peak temperature dropped to 147℃, indicating that excessive UV absorber interfered with the absorption of resin reaction heat and the curing process. The UV index (GU) decreased from 58.4 GU before irradiation to 40.6 GU after irradiation, indicating that insufficient whitening agent led to an imbalance in UV protection, resulting in photodegradation on the resin surface; the color difference ΔE*ab reached 0.92, indicating that the imbalance in the additive ratio exacerbated the color shift after irradiation.

[0211] The results from Comparative Examples 1-5 show that within the specified ratio range (0.03-0.035 parts UV absorber and 0.0025-0.0035 parts whitening agent), the UV absorber preferentially absorbs the UVB band (280-320nm), while the whitening agent absorbs the UVA band (320-400nm) and emits blue light through fluorescence, thus reducing resin yellowing. The synergistic effect of the two is mainly manifested in: optimizing gloss, balancing curing and mechanical properties, and improving weather resistance. When the additive ratio exceeds the above range, the synergistic effect is disrupted, and the functions of the two will antagonize each other, leading to decreased curing efficiency and an imbalance between mechanical properties and weather resistance.

[0212] Comparative Example 6, without the addition of methylpropylene glycol, resulted in a yellow resin color. The absence of methylpropylene glycol led to a decrease in molecular chain flexibility and insufficient filler wetting. The resin strength was 33.6 GU before light exposure and decreased to 18.1 GU after light exposure. The color difference ΔE*ab reached 1.27, indicating that the absence of methylpropylene glycol significantly reduced its UV aging resistance. The oil absorption value reached 2248 cP, indicating abnormal molecular chain flexibility and increased oil absorption due to a loose crosslinking network. The gel time and post-curing time were shortened, but the exothermic peak was 150℃, indicating insufficient curing reactivity and a decrease in crosslinking density.

[0213] Comparative Example 7, without the addition of propylene glycol, resulted in a pale yellow resin color, with a viscosity of 35.1 GU before light exposure and 19.9 GU after light exposure. The color difference ΔE*ab reached 1.24, indicating that the lack of propylene glycol led to a significant decrease in its UV aging resistance. The viscosity and oil absorption value both increased, indicating abnormal molecular chain flexibility or a loose cross-linking network.

[0214] As shown in Table 4, when the weight ratio of propylene glycol to methyl propylene glycol is in the range of 1.0 to 1.3:1, the resin exhibits the best water-white color, with a color difference ΔE*ab of less than 0.71 and an oil absorption value of 2022 to 2170 cP. Under this ratio, the exothermic peak temperature is stable at 154 to 159℃, indicating that the reactivity is moderate and the resin viscosity is maintained in the optimal processing range of 300 to 350 mPa·s.

[0215] When the weight ratio of propylene glycol to methyl propylene glycol is more than 1.3:1, obvious performance deterioration occurs, the color turns to light yellow to yellow, the color difference of the artware increases, the oil absorption value increases, and the exothermic peak temperature decreases. When the weight ratio of propylene glycol to methyl propylene glycol is less than 1:1, the process performance deteriorates, the color stability decreases, and the exothermic peak temperature decreases.

[0216] In Comparative Example 8, the weight ratio of copper iso-octoate to copper naphthenate is greater than 4:1, resulting in prolonged gel time and post-curing time, increased oil absorption value, decreased curing efficiency and gloss, and no synergistic effect is achieved. In Comparative Example 9, the weight ratio of copper iso-octoate to copper naphthenate is less than 1.5:1, resulting in prolonged gel time and post-curing time, increased oil absorption value, and decreased tensile strength, bending strength and gloss.

[0217] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application in other forms. Any person skilled in the art can modify or change the above-mentioned technical content to obtain equivalent embodiments. However, any simple modification, equivalent change and modification made on the basis of the technical essence of the present application to the above embodiments, without departing from the technical solution of the present application, still falls within the protection scope of the present application.

Claims

1. An unsaturated polyester resin for imitation jade handicrafts, characterized in that, By weight, it consists of the following components: 16.2–16.8 parts diethylene glycol, 6.0–6.6 parts methyl propylene glycol, 6.6–7.8 parts propylene glycol, 11.73–13 parts maleic anhydride, 25–25.53 parts phthalic anhydride, 0.052–0.058 parts antioxidant, 0.0038–0.0043 parts polymerization inhibitor, 0.052–0.058 parts paraffin wax, 0.0009–0.0012 parts stabilizer, 0.03–0.035 parts ultraviolet absorber, 0.0025–0.0035 parts whitening agent, and 31.8418–32.6215 parts diluent; The weight ratio of propylene glycol to methyl propylene glycol is 1.0–1.3:1; methyl propylene glycol accounts for 20–22% of the total diols; the weight ratio of maleic anhydride to phthalic anhydride is 0.46–0.52:1; and the weight ratio of ultraviolet absorber to whitening agent is 8.75–14.0:

1.

2. The unsaturated polyester resin for imitation jade crafts according to claim 1, characterized in that: The weight ratio of maleic anhydride to phthalic anhydride is 0.47 to 0.51:

1.

3. The unsaturated polyester resin for imitation jade handicrafts according to claim 1, characterized in that: The stabilizer is at least one of copper isooctanoate or copper naphthenate.

4. The unsaturated polyester resin for imitation jade handicrafts according to claim 3, characterized in that: The weight ratio of copper isooctanoate to copper naphthenate is 1.5 to 4:

1.

5. The unsaturated polyester resin for imitation jade handicrafts according to claim 1, characterized in that: The ultraviolet absorber is 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole or 2-(2'-hydroxy-3,5'-di-tert-pentylphenyl)benzotriazole; the whitening agent is 2,5-bis(5-tert-butyl-2-benzoxazolyl)thiophene.

6. A method for preparing an unsaturated polyester resin for imitation jade handicrafts according to any one of claims 1 to 5, characterized in that, Includes the following steps: (1) Diethylene glycol, methyl propylene glycol, propylene glycol, maleic anhydride, phthalic anhydride and antioxidant are added to the reactor in parts by weight, the temperature is raised to 155-165℃, and then kept at the temperature for 0.5-1.0h, and then the temperature is raised to 200-210℃. (2) React at 200–210℃ for 2–3 hours; dehydrate; (3) Cool down and add polymerization inhibitor and paraffin by weight; cool down again and add stabilizer and diluent by weight; continue cooling down and add ultraviolet absorber and whitening agent by weight; mix well to obtain unsaturated polyester resin for imitation jade crafts.

7. The method for preparing an unsaturated polyester resin for imitation jade crafts according to claim 6, characterized in that: The heating rate for step (1) to continue heating to 200-210℃ is 12-14℃ / h.

8. The method for preparing an unsaturated polyester resin for imitation jade crafts according to claim 6, characterized in that: Step (2) React at 200-210℃ for 2-3 hours; dehydrate until the acid value reaches 20-25 mg KOH / g.

9. The method for preparing an unsaturated polyester resin for imitation jade crafts according to claim 6, characterized in that: The specific operation of step (3) is as follows: cool down to 170-190℃ and add polymerization inhibitor and paraffin according to weight; cool down to 90-110℃ and add stabilizer and diluent according to weight; cool down to 50-60℃ and add ultraviolet absorber and whitening agent according to weight, and mix well; to obtain unsaturated polyester resin for imitation jade crafts.