Unsaturated polyester and preparation method therefor

Abstract

The present application provides an unsaturated polyester and a preparation method therefor. The starting materials of the unsaturated polyester comprise an unsaturated dicarboxylic acid, a saturated dicarboxylic acid, a polyol, an acrylate crosslinking agent, and a polymerization inhibitor. The chemical formula of the polyol comprises R1, where R1 comprises C and H. The unsaturated polyester provided in the present application possesses both strength and toughness, while eliminating the hazards of styrene present in existing unsaturated polyesters.

Description

An unsaturated polyester and its preparation method Technical Field

[0001] This application relates to an unsaturated polyester and its preparation method, belonging to the field of polymer materials. Background Technology

[0002] Unsaturated polyesters are prepared by reacting polyester monomers containing unsaturated bonds in the main chain with vinyl monomers. They possess high tensile, flexural, and compressive strength, and exhibit good resistance to water, dilute acids, and dilute alkalis, making them widely used in artificial stone, fiberglass, coatings, and automotive industries. Unsaturated polyesters offer flexible application options, allowing for room temperature curing. Different application techniques can be selected to meet various needs; fiberglass and artificial stone are often cast, while floor coatings are sprayed. Other methods include spraying, large-diameter winding, and hand lay-up. However, the significant shrinkage rate of unsaturated polyesters after curing has become a bottleneck limiting their further application and development.

[0003] Styrene is commonly used as a crosslinking agent. Styrene has a strong copolymerization ability with polyester and can also adjust the viscosity of polyester, facilitating construction. However, styrene-based unsaturated polyesters become hard and brittle after curing, making it difficult to meet the performance requirements of some practical applications such as quartz stone slabs and polyester anti-corrosion flooring. This is mainly because during the curing process of unsaturated polyester, some styrene easily self-polymerizes, forming rigid polystyrene. Furthermore, styrene is listed as a Group 2B carcinogen in the 2017 list of carcinogens published by the International Agency for Research on Cancer (IARC) of the World Health Organization. Styrene has a vapor pressure of 0.7 kPa (20°C) and a boiling point of 145°C. During the production and construction of unsaturated polyester, styrene is easily volatilized. The curing of unsaturated polyester generates a large amount of heat, which further exacerbates the volatilization of styrene, resulting in strong odors in the workshop, serious environmental pollution, and harm to workers' health.

[0004] To reduce the harm caused by styrene, the development of styrene-free unsaturated polyesters has become a research focus in this field. One major direction is to replace styrene with acrylate compounds as crosslinking agents. However, acrylate compounds and unsaturated polyesters have a low copolymerization tendency, the reaction process is too hot and surface oxygen inhibits polymerization, resulting in incomplete resin curing, low polyester crosslinking degree, and although the material toughness is improved, the strength is reduced too much, making it difficult to meet the needs of most application scenarios.

[0005] Therefore, there is an urgent need to develop unsaturated polyesters with excellent processing performance, mechanical properties and low volume shrinkage to facilitate the application of unsaturated polyesters. Summary of the Invention

[0006] This application provides an unsaturated polyester with excellent processing properties, mechanical properties and low volume shrinkage.

[0007] This application also provides a method for preparing unsaturated polyester, which is simple in process and can produce unsaturated polyester with excellent processing performance, mechanical properties and low volume shrinkage.

[0008] This application provides an unsaturated polyester, wherein the raw materials for the unsaturated polyester include unsaturated diacids, saturated diacids, polyols, acrylate crosslinking agents, and polymerization inhibitors; the polyol is shown in Formula 1:

[0009] R1 includes C and H.

[0010] The unsaturated polyester as described above comprises, by weight parts: 11-93 parts by weight of unsaturated diacid, 29-135 parts by weight of saturated diacid, 90-130 parts by weight of polyol, 64-230 parts by weight of acrylate crosslinking agent, and 0.04-0.2 parts by weight of polymerization inhibitor.

[0011] In the unsaturated polyester described above, the number of carbon atoms in R1 is 1-5.

[0012] The unsaturated polyester as described above, wherein R1 comprises at least one of alkyl and alkenyl groups.

[0013] The unsaturated polyester described above comprises, by weight, 4-12 parts of monohydric alcohol.

[0014] The unsaturated polyester as described above, wherein the monohydric alcohol comprises at least one of n-butanol, isooctanol, n-propanol, ethanol, and octanol.

[0015] The unsaturated polyester as described above, wherein the unsaturated dicarboxylic acid includes at least one of maleic anhydride, maleic acid, and fumaric acid.

[0016] And / or, the saturated dicarboxylic acid includes at least one of phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, and succinic acid;

[0017] And / or, the acrylate crosslinking agent includes at least one of isooctyl acrylate, methyl methacrylate, butyl acrylate, soybean oil epoxidized acrylate, hydroxyethyl methacrylate, butyl methacrylate, and isobornyl methacrylate.

[0018] The unsaturated polyester as described above has a tensile strength of not less than 29.6 MPa, a flexural strength of not less than 42.9 MPa, and a total volume shrinkage rate of not more than 3.0%.

[0019] This application further provides a method for preparing the unsaturated polyester as described above, comprising the following steps:

[0020] 1) The first mixture, including unsaturated dicarboxylic acid, saturated dicarboxylic acid, and polyol, is reacted at 150-180℃ for 0.5-2h, and then heated to 190-210℃ for high-temperature treatment to obtain a second mixture with an acid value of less than 50mg KOH / g.

[0021] 2) After cooling the second mixture to 120-150℃, vacuum cooling treatment is performed. When the acid value is less than 10mg KOH / g and the temperature is not higher than 70℃, acrylate crosslinking agent and polymerization inhibitor are added to carry out polymerization reaction to obtain the unsaturated polyester.

[0022] The preparation method described above further includes adding a monohydric alcohol during the high-temperature treatment, comprising the following steps:

[0023] A first mixture comprising an unsaturated dicarboxylic acid, a saturated dicarboxylic acid, and a polyol is reacted at 150-180℃ for 0.5-2 hours, and then heated to 190-210℃ for high-temperature treatment. When the acid value of the first mixture is less than 300 mg KOH / g, a monohydric alcohol is added, and the high-temperature treatment is continued to obtain a second mixture with an acid value less than 50 mg KOH / g.

[0024] Preferably, the unsaturated dicarboxylic acid comprises 11-93 parts by weight, the saturated dicarboxylic acid comprises 29-135 parts by weight, the polyol comprises 90-130 parts by weight, the acrylate crosslinking agent comprises 64-230 parts by weight, and the polymerization inhibitor comprises 0.04-0.2 parts by weight.

[0025] The unsaturated polyester provided in this application is prepared using specific mass parts of unsaturated diacid, diacid acrylate crosslinking agent, polymerization inhibitor, and polyol with a specific structure as raw materials. By using a polyol with the structure shown in Formula 1 as the polyester reactive monomer, the charge density of the polyester double bond can be changed, so that the prepared polyester and acrylate have a stronger copolymerization tendency. The unsaturated polyester prepared by this method has higher strength after curing, and the material toughness is also improved, and the shrinkage rate after curing is lower. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] Styrene is typically used as a crosslinking agent in the production of unsaturated polyester. However, the curing of unsaturated polyester generates a lot of heat, which can easily cause styrene to volatilize, resulting in a strong odor in the workshop, serious environmental pollution, and harm to the health of workers.

[0028] To reduce the harmful effects of styrene, acrylate compounds are currently widely used as crosslinking agents to replace styrene. However, acrylates have a low tendency to copolymerize with unsaturated polyesters. This is because the unsaturated double bonds in unsaturated polyesters are provided by maleic anhydride, which is an electron-deficient group. Acrylic acrylates have a lower double bond charge density, resulting in a lower copolymerization tendency. Furthermore, acrylates have a higher tendency to self-polymerize, leading to higher exothermic reactions, rapid temperature rise during the reaction, and surface oxygen inhibition, resulting in higher residue levels and lower curing degrees. This results in incomplete resin curing, lower polyester crosslinking, and while the material's toughness is improved, its strength is significantly reduced, making it unsuitable for most applications.

[0029] This application provides an unsaturated polyester, the raw materials of which include unsaturated diacids, saturated diacids, polyols, acrylate crosslinking agents, and polymerization inhibitors; the polyol is shown in Formula 1:

[0030] R1 includes C and H.

[0031] In this application, unsaturated dicarboxylic acids refer to organic acids or anhydrides that include at least one carbon-carbon double bond and two carboxylic acid groups. Saturated dicarboxylic acids refer to dicarboxylic acids or anhydrides in which all carbon-carbon bonds in the molecular structure are single bonds and no double bonds exist. Acrylic ester crosslinking agents refer to compounds with acrylate as the main structural unit.

[0032] This application does not impose any particular limitation on the chemical structure of unsaturated dicarboxylic acids, saturated dicarboxylic acids, and acrylate crosslinking agents; the above-mentioned substances with common chemical structures in the art can be selected.

[0033] The unsaturated polyester synthesized using the aforementioned raw materials exhibits excellent processing performance, mechanical properties, and low volume shrinkage. The inventors analyzed this and believe the reason may lie in the fact that traditional unsaturated polyesters use maleic anhydride as the polyester monomer and styrene as the crosslinking agent because the double bond of maleic anhydride is an electron-deficient group, while styrene, due to the presence of the benzene ring, has a high double bond charge density and therefore a strong tendency to act as a colloidal tool. Acrylic esters, on the other hand, have a lower double bond charge density and a lower tendency to copolymerize with maleic anhydride. Using the polyol shown in Formula 1 of this application, the hydroxyl groups at specific positions can provide suitable charges to the polyester double bonds, altering the copolymerization tendency with acrylates. Simultaneously, the presence of the R1 group can reduce the crystallinity of the polyester, thereby giving the unsaturated polyester excellent processing performance, relatively superior mechanical properties, and a low volume shrinkage, promoting the development of unsaturated polyesters. Furthermore, the unsaturated polyester provided in this application does not contain styrene as a raw material, and the styrene content in the product is 0%, eliminating the harm to human health caused by styrene in existing unsaturated polyesters during production and use.

[0034] Meanwhile, the inventors discovered through research that the unsaturated polyester provided in this application has a more suitable gel time during the curing process, ensuring better construction conditions, while significantly reducing the overall volume shrinkage rate, ensuring the geometric shape and dimensional stability of the finished product, and expanding the application scenarios of unsaturated polyester.

[0035] Furthermore, in one specific embodiment of this application, the raw materials for the unsaturated polyester include, by weight parts: 11-93 parts by weight of unsaturated diacid, 29-135 parts by weight of saturated diacid, 90-130 parts by weight of polyol, 64-230 parts by weight of acrylate crosslinking agent, and 0.04-0.2 parts by weight of polymerization inhibitor.

[0036] Preferably, the raw materials include, by weight, 20-50 parts of unsaturated diacid, 50-100 parts of saturated diacid, 90-100 parts of polyol, 100-150 parts of acrylate crosslinking agent, and 0.05-0.1 parts of polymerization inhibitor.

[0037] Specifically, the mass fractions of unsaturated dicarboxylic acids include, but are not limited to, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, or any combination thereof; the mass fractions of saturated dicarboxylic acids include, but are not limited to, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, or any combination thereof; the mass fractions of polyols include, but are not limited to, 90 parts, 92 parts, 94 parts, 96 parts, 98 parts, 100 parts, or any combination thereof; the mass fractions of acrylate crosslinking agents include, but are not limited to, 100 parts, 110 parts, 120 parts, 130 parts, 140 parts, 150 parts, or any combination thereof; and the mass fractions of polymerization inhibitors include, but are not limited to, 0.05 parts, 0.06 parts, 0.07 parts, 0.08 parts, 0.09 parts, 0.10 parts, or any combination thereof.

[0038] When the mass fraction of unsaturated polyester raw materials meets the above range, the synergistic relationship between the components can be better realized, the crosslinking density can be further improved, and the toughness and strength of unsaturated polyester can be enhanced.

[0039] Furthermore, in one specific embodiment of this application, the number of carbon atoms in R1 is 1-5.

[0040] In detail, the number of carbon atoms in R1 includes any one of 1, 2, 3, 4, or 5.

[0041] When the number of carbon atoms in R1 meets the above range, the strength and toughness of the unsaturated polyester are superior. This may be because the polyol with the above number of carbon atoms can better regulate the degree of crosslinking between the components during the polyester preparation process, adjust the flexibility of the unsaturated polyester and the rate of the later curing reaction, thereby affecting the strength and toughness of the unsaturated polyester.

[0042] When R1 meets the above range, it can change the charge properties of the unsaturated polyester while ensuring the mechanical properties of the cured polyester. This may be because alkyl groups are electron-donating groups, which can enhance the polarity of the polyester. The increased double bond charge density in the unsaturated polyester makes it easier to copolymerize with acrylates. At the same time, the presence of alkyl groups in the side chain can reduce the crystallinity of the polyester, giving it better solubility and dispersibility in acrylates. The cured material has superior strength and toughness.

[0043] Furthermore, in one specific embodiment of the present invention, R1 includes at least one of alkyl and alkenyl groups.

[0044] The structure type of R1 can be selected according to actual needs, such as straight chain structure, branched chain structure or ring structure.

[0045] Furthermore, in one specific embodiment of this application, the raw materials include 4-12 parts by mass of monohydric alcohol.

[0046] In detail, the mass fractions of the monohydric alcohol include, but are not limited to, a range of 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, or any two of these.

[0047] It should be noted that the addition of monohydric alcohol will not have a significant impact on the mass ratio of other raw materials, and the mass ratio of other raw materials can still be defined according to the mass ratio described above.

[0048] The inventors discovered through research that the addition of monohydric alcohols can not only participate in the synthesis reaction and improve the toughness of unsaturated polyesters, but also play a role in end-capping, effectively controlling the molecular weight of unsaturated polyesters and expanding the application areas and scenarios of unsaturated polyesters.

[0049] Furthermore, in one specific embodiment of this application, the monohydric alcohol includes at least one of n-butanol, isooctanol, n-propanol, ethanol, and octanol.

[0050] Furthermore, in one specific embodiment of this application, the unsaturated dicarboxylic acid includes at least one of maleic anhydride, maleic acid, and fumaric acid; and / or, the saturated dicarboxylic acid includes at least one of phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, and succinic acid; and / or, the acrylate crosslinking agent is selected from at least one of isooctyl acrylate, methyl methacrylate, butyl acrylate, epoxidized soybean oil acrylate, hydroxyethyl methacrylate, butyl methacrylate, and isobornyl methacrylate.

[0051] In order to make unsaturated polyester suitable for common process requirements, in another specific embodiment, the molar ratio of acrylate crosslinking agent to unsaturated dicarboxylic acid is (1.5-5):1, preferably (2-4):1, at which time the double bonds of unsaturated polyester and crosslinking agent can be copolymerized better.

[0052] Furthermore, in one specific embodiment of this application, the tensile strength of the unsaturated polyester is not less than 29.6 MPa, the flexural strength is not less than 42.9 MPa, and the total volume shrinkage rate is not higher than 3.0%.

[0053] The tensile strength and flexural strength of unsaturated polyester can be tested according to the standard test scheme of GB / T 2567-2021, and the total volume shrinkage rate can be tested according to GB / T 24148.9-2014.

[0054] The unsaturated polyester provided in this application has a tensile strength of not less than 29.6 MPa, a flexural strength of not less than 42.9 MPa, and a total volume shrinkage rate of not more than 3.0%, which demonstrates that the unsaturated polyester has excellent mechanical properties and a lower volume shrinkage rate compared with traditional styrene-type unsaturated polyester.

[0055] This application further provides a method for preparing the unsaturated polyester as described above, comprising the following steps:

[0056] 1) The first mixture, including unsaturated dicarboxylic acid, saturated dicarboxylic acid, and polyol, is reacted at 150-180℃ for 0.5-2h, and then heated to 190-210℃ for high-temperature treatment to obtain a second mixture with an acid value of less than 50mg KOH / g.

[0057] 2) After cooling the second mixture to 120-150℃, vacuum cooling treatment is performed. When the acid value is less than 10mg KOH / g and the temperature is not higher than 70℃, acrylate crosslinking agent and polymerization inhibitor are added to carry out polymerization reaction to obtain unsaturated polyester.

[0058] In detail, in step 1), unsaturated dicarboxylic acid, saturated dicarboxylic acid and polyol are weighed according to a certain mass ratio and added to a three-necked flask to obtain a first mixture. Nitrogen gas is introduced and the mixture is stirred to ensure that the three are fully mixed and reacted. At the same time, the temperature is gradually raised to 150-180℃ and maintained for 0.5-2 hours. Then the temperature is raised to 190-210℃ to obtain a second mixture with an acid value of less than 50 mg KOH / g.

[0059] In this application, acid value represents the number of milligrams of potassium hydroxide (KOH) required to neutralize 1 gram of a chemical substance. Common methods in the art can be used to detect the acid value of the mixture at different stages, such as GB / T 2895-2008. In the reaction process of unsaturated diacids, saturated diacids, and polyols, the acid value reflects the degree of esterification. When the acid value is less than 50 mg KOH / g, the esterification reaction is considered essentially complete.

[0060] It is understandable that aromatic hydrocarbons can be added to the first mixture in order to save energy. This application does not limit the specific type of aromatic hydrocarbon, and common aromatic hydrocarbons such as benzene, toluene, and xylene can be selected.

[0061] To ensure the safety of the reaction, the reflux temperature can be monitored in real time during step 1 and controlled to be less than 110°C.

[0062] In step 1), unsaturated and saturated diacids react with polyols via esterification to form polyester segments. As the reaction time and temperature increase, the esterification reaction proceeds further, the polyester chains lengthen, and the molecular weight gradually increases. During this stage, cross-linking of the polyester chains also occurs; in particular, the double bonds of the unsaturated diacids can form cross-linked structures through free radical polymerization or thermal cross-linking reactions, enhancing the mechanical properties and chemical resistance of the polyester. The final second mixture obtained is a prepolymer of unsaturated polyester.

[0063] In step 2), after cooling the second mixture to 120-150℃, stop the nitrogen gas supply and perform vacuum cooling to remove residual solvent and moisture. At the same time, adjust the acid value in the polyester. When the acid value is less than 10mg KOH / g and the temperature is not higher than 70℃, add acrylate crosslinking agent and polymerization inhibitor to carry out polymerization reaction to obtain unsaturated polyester.

[0064] To improve the efficiency of the polymerization reaction, the reaction system can be stirred after adding acrylate crosslinking agents and polymerization inhibitors to ensure sufficient contact between the various substances.

[0065] The preparation method provided in this application is simple and can produce unsaturated polyester with excellent strength and toughness. Moreover, styrene is not used as a raw material in the preparation process, thus eliminating the harm of styrene to the human body.

[0066] It is understandable that the reaction solution containing unsaturated polyester can be solidified after the polymerization reaction is completed to obtain solid unsaturated polyester.

[0067] This application does not limit the specific method of curing treatment or the curing agent, initiator, etc. that can be selected. Common methods, curing agents and initiators in the art can be used for curing treatment.

[0068] In one specific embodiment, the curing agent is cobalt isooctanoate V388, the mass ratio of the curing agent to the unsaturated polyester is 0.01:1, the initiator is methyl ethyl ketone peroxide M-50VR, and the mass ratio of the initiator to the unsaturated polyester is 0.015:1.

[0069] Furthermore, in one specific embodiment of this application, the addition of a monohydric alcohol during the high-temperature treatment process includes the following steps:

[0070] The first mixture, consisting of unsaturated dicarboxylic acid, saturated dicarboxylic acid, and polyol, is reacted at 150-180℃ for 0.5-2h, and then heated to 190-210℃ for high-temperature treatment. When the acid value of the first mixture is less than 300mg KOH / g, a monohydric alcohol is added, and the high-temperature treatment continues to obtain a second mixture with an acid value less than 50mg KOH / g.

[0071] Preferably, the composition includes 11-93 parts by weight of unsaturated dicarboxylic acid, 29-135 parts by weight of saturated dicarboxylic acid, 90-130 parts by weight of polyol, 64-230 parts by weight of acrylate crosslinking agent, and 0.04-0.2 parts by weight of polymerization inhibitor.

[0072] In detail, unsaturated dicarboxylic acid, saturated dicarboxylic acid, and polyol are weighed according to certain mass proportions and added to a three-necked flask to obtain a first mixture. Nitrogen gas is introduced and the mixture is stirred to ensure thorough mixing and reaction. Simultaneously, the temperature is gradually raised to 150-180℃ and maintained for 0.5-2 hours. Then, the temperature is raised to 190-210℃ for high-temperature treatment. When the acid value of the first mixture is less than 300 mg KOH / g, a certain mass proportion of monohydric alcohol is added and the high-temperature treatment continues until a second mixture with an acid value less than 50 mg KOH / g is obtained.

[0073] In this process, unsaturated and saturated diacids undergo esterification with polyols to form ester bonds, combining diacid and polyol molecules into polyester chains. When the acid value of the first mixture drops to less than 300 mg KOH / g, the addition of monohydric alcohol can not only neutralize the residual acidic substances, but also adjust the end structure of the polyester molecular chain, preparing for the crosslinking reaction in the subsequent step 2), and further improving the strength and toughness of the unsaturated polyester.

[0074] The present application will be further described below through specific embodiments. The embodiments described in this application are only for illustration and do not limit the scope of this application.

[0075] The main raw material sources used in this application's embodiments are as follows; unless otherwise specified, all other raw materials are common commercially available: maleic anhydride (Qixiang Tengda), maleic acid (Qixiang Tengda), fumaric acid (Qixiang Tengda), phthalic anhydride (Ruifeng New Materials), isophthalic acid (Ruifeng New Materials), terephthalic acid (Ruifeng New Materials), 1,3-butanediol (Wanhua Chemical), 1,3-pentanediol (Wanhua Chemical), 1,3-hexanediol (Wanhua Chemical), n-butanol (Wanhua Chemical), ethanol (Jiangtian Chemical), n-propanol (Jiangtian Chemical), isopropanol (Jiangtian Chemical), butyl acrylate (Wanhua Chemical), isooctyl acrylate (Wanhua Chemical), 2-butyl methacrylate (Wanhua Chemical), hydroxyethyl methacrylate (Wanhua Chemical), cobalt isooctanoate (Norinon), methyl ethyl ketone peroxide (Norinon).

[0076] Example 1

[0077] The method for preparing unsaturated polyester provided in this embodiment includes the following steps:

[0078] 1. Weigh 49 parts by weight of maleic anhydride, 59.2 parts by weight of phthalic anhydride, and 108 parts by weight of 1,3-butanediol and add them to a three-necked flask. Add 116 parts by weight of toluene, purge with nitrogen and stir to obtain the first mixture. Gradually raise the temperature to 150°C, maintain the reaction for 2 hours, then raise the temperature to 190°C and control the reflux temperature to be less than 110°C. When the acid value is 300 mg KOH / g, add 7.4 parts by weight of n-butanol and continue the reaction to obtain the second mixture with an acid value of less than 50 mg KOH / g.

[0079] 2. Cool the second mixture to 120℃ and stop the nitrogen flow. Start vacuuming. When the acid value is less than 10mg KOH / g, cool to 60℃ and add 165.6 parts by mass of isooctyl acrylate and 0.04 parts by mass of hydroquinone to carry out the polymerization reaction. After the polymerization reaction is completed, carry out curing treatment. Add cobalt isooctanoate V388 and 1.5% methyl ethyl ketone peroxide M-50VR at 25℃ to form a curing system and obtain unsaturated polyester.

[0080] Cobalt isooctanoate V388 accounts for 1 wt% of the curing system, and methyl ethyl ketone peroxide M-50VR accounts for 1.5 wt% of the curing system.

[0081] The gel time during the curing process was tested according to GB / T 24148.7-2014, and the total volume shrinkage rate before and after curing was tested according to GB / T 24148.9-2014. The specific results are shown in Table 1.

[0082] Example 2

[0083] The method for preparing unsaturated polyester provided in this embodiment includes the following steps:

[0084] 1. Weigh 11.6 parts by weight of maleic acid, 133.2 parts by weight of isophthalic acid, and 104 parts by weight of 1,3-pentanediol and add them to a three-necked flask. Add 63.4 parts by weight of xylene, purge with nitrogen and stir to obtain the first mixture. Gradually raise the temperature to 160°C and maintain the reaction for 1.5 hours. Then raise the temperature to 200°C and control the reflux temperature to be less than 110°C. When the acid value is 300 mg KOH / g, add 4.6 parts by weight of ethanol and continue the reaction to obtain the second mixture with an acid value of less than 50 mg KOH / g.

[0085] 2. Cool the second mixture to 130°C and stop the nitrogen flow. Start vacuuming. When the acid value is less than 10 mg KOH / g, cool to 70°C and add 64 parts by mass of butyl acrylate and 0.06 parts by mass of p-tert-butylcatechol to carry out the polymerization reaction. After the polymerization reaction is completed, carry out the curing treatment according to the curing treatment steps in Example 1 to obtain unsaturated polyester.

[0086] The gelation time and total volume shrinkage rate were tested according to the method in Example 1, and the specific results are shown in Table 1.

[0087] Example 3

[0088] The method for preparing unsaturated polyester provided in this embodiment includes the following steps:

[0089] 1. Weigh 92.8 parts by weight of fumaric acid, 29.6 parts by weight of terephthalic acid, and 129.8 parts by weight of 1,3-hexanediol and add them to a three-necked flask. Add 243 parts by weight of benzene, purge with nitrogen and stir to obtain the first mixture. Gradually raise the temperature to 180°C, maintain the reaction for 0.5 hours, then raise the temperature to 210°C and control the reflux temperature to be less than 110°C. When the acid value is 300 mg KOH / g, add a monohydric alcohol and continue the reaction to obtain the second mixture with an acid value of less than 50 mg KOH / g.

[0090] 2. Cool the second mixture to 120°C and stop the nitrogen flow. Start vacuuming. When the acid value is less than 10 mg KOH / g, cool to 50°C and add 227.2 parts by weight of 2-butyl methacrylate and 0.04 parts by weight of hydroquinone to carry out the polymerization reaction. After the polymerization reaction is completed, carry out the curing treatment according to the curing treatment steps in Example 1 to obtain unsaturated polyester.

[0091] The gelation time and total volume shrinkage rate were tested according to the method in Example 1, and the specific results are shown in Table 1.

[0092] Example 4

[0093] The method for preparing unsaturated polyester provided in this embodiment includes the following steps:

[0094] 1. Weigh 29.4 parts by weight of maleic anhydride, 103.6 parts by weight of phthalic anhydride, and 90 parts by weight of 1,3-butanediol and add them to a three-necked flask. Add 156 parts by weight of toluene, purge with nitrogen and stir to obtain the first mixture. Gradually raise the temperature to 180°C and maintain the reaction for 1.5 hours. Then raise the temperature to 200°C and control the reflux temperature to be less than 110°C. When the acid value is 300 mg KOH / g, add a monohydric alcohol and continue the reaction to obtain the second mixture with an acid value of less than 50 mg KOH / g.

[0095] 2. Cool the second mixture to 130°C and stop the nitrogen flow. Start vacuuming. When the acid value is less than 10 mg KOH / g, cool to 60°C and add 156 parts by weight of hydroxyethyl methacrylate and 0.04 parts by weight of catechol to carry out the polymerization reaction. After the polymerization reaction is completed, carry out the curing treatment according to the curing treatment steps in Example 1 to obtain unsaturated polyester.

[0096] The gelation time and total volume shrinkage rate were tested according to the method in Example 1, and the specific results are shown in Table 1.

[0097] Example 5

[0098] The method for preparing unsaturated polyester provided in this embodiment includes the following steps:

[0099] 1. Weigh 40 parts by mass of maleic anhydride, 80 parts by mass of phthalic anhydride, and 95 parts by mass of 1,3-butanediol and add them to a three-necked flask. Add 116 parts by mass of toluene, purge with nitrogen and stir to obtain the first mixture. Gradually raise the temperature to 160°C, maintain the reaction for 2 hours, and then raise the temperature to 200°C. Control the reflux temperature to be less than 110°C. When the acid value is 300 mg KOH / g, add 10 parts by mass of n-butanol and continue the reaction to obtain the second mixture with an acid value of less than 50 mg KOH / g.

[0100] 2. Cool the second mixture to 120°C and stop the nitrogen flow. Start vacuuming. When the acid value is less than 10 mg KOH / g, cool to 60°C and add 130 parts by weight of isooctyl acrylate and 0.08 parts by weight of hydroquinone to carry out the polymerization reaction. After the polymerization reaction is completed, carry out the curing treatment according to the curing treatment steps in Example 1 to obtain unsaturated polyester.

[0101] The gelation time and total volume shrinkage rate were tested according to the method in Example 1, and the specific results are shown in Table 1.

[0102] Example 6

[0103] The preparation method of the unsaturated polyester provided in this embodiment is basically the same as that in Example 5, except that:

[0104] In step 1), 1,3-butanediol is replaced with 1,3-octanediol.

[0105] The gelation time and total volume shrinkage rate were tested according to the method in Example 1, and the specific results are shown in Table 1.

[0106] Example 7

[0107] The preparation method of unsaturated polyester provided in this embodiment is basically the same as that in Example 5, except that:

[0108] In step 1), n-butanol is not added.

[0109] The gelation time and total volume shrinkage rate were tested according to the method in Example 1, and the specific results are shown in Table 1.

[0110] Comparative Example 1

[0111] The preparation method of the unsaturated polyester provided in this comparative example is basically the same as that in Example 1, except that:

[0112] In step 1), 1,3-butanediol is replaced with 1,2-propanediol.

[0113] The gelation time and total volume shrinkage rate were tested according to the method in Example 1, and the specific results are shown in Table 1.

[0114] Comparative Example 2

[0115] The preparation method of the unsaturated polyester provided in this comparative example is basically the same as that in Example 1, except that:

[0116] In step 1), 1,3-butanediol is replaced with 1,2-propanediol, and isooctyl acrylate is replaced with styrene.

[0117] The gelation time and total volume shrinkage rate were tested according to the method in Example 1, and the specific results are shown in Table 1.

[0118] Comparative Example 3

[0119] The preparation method of the unsaturated polyester provided in this comparative example is basically the same as that in Example 1, except that:

[0120] In step 1), 1,3-butanediol is replaced with 2-methyl-1,3-propanediol.

[0121] The gelation time and total volume shrinkage rate were tested according to the method in Example 1, and the specific results are shown in Table 1.

[0122] Test case

[0123] The tensile strength, tensile modulus, elastic modulus, and elongation at break of all solid unsaturated polyesters provided in the examples and comparative examples were tested according to GB / T 2567-2021. The specific test results are shown in Table 1.

[0124] Table 1

[0125] As shown in Table 1, the unsaturated polyesters provided in Examples 1-7 have a tensile strength of not less than 29.6 MPa, a flexural strength of not less than 42.9 MPa, and a total volume shrinkage rate of not more than 3.0%, which are significantly better than the unsaturated polyesters provided in Comparative Examples 1-3. At the same time, the unsaturated polyesters provided in Examples 1-7 have a longer gel time than the unsaturated polyesters provided in Comparative Examples 1-3, which can ensure sufficient reaction time during construction. Meanwhile, the total volume shrinkage rate is also reduced, which improves the accuracy and precision of construction.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of this application.

Claims

1. An unsaturated polyester, characterized in that, The raw materials for the unsaturated polyester include unsaturated diacids, saturated diacids, polyols, acrylate crosslinking agents, and polymerization inhibitors; the polyols are shown in Formula 1: R1 includes C and H.

2. The unsaturated polyester according to claim 1, characterized in that, The raw materials of the unsaturated polyester include, by weight, 11-93 parts of unsaturated diacid, 29-135 parts of saturated diacid, 90-130 parts of polyol, 64-230 parts of acrylate crosslinking agent, and 0.04-0.2 parts of polymerization inhibitor.

3. The unsaturated polyester according to claim 1 or 2, characterized in that, The number of carbon atoms in R1 is 1-5.

4. The unsaturated polyester according to claim 3, characterized in that, R1 includes at least one of alkyl and alkenyl groups.

5. The unsaturated polyester according to any one of claims 1-4, characterized in that, The raw materials include, by weight, 4-12 parts of monohydric alcohol.

6. The unsaturated polyester according to claim 5, characterized in that, The monohydric alcohol includes at least one of n-butanol, isooctanol, n-propanol, ethanol, and octanol.

7. The unsaturated polyester according to any one of claims 1-6, characterized in that, The unsaturated dicarboxylic acid includes at least one of maleic anhydride, maleic acid, and fumaric acid. And / or, the saturated dicarboxylic acid includes at least one of phthalic anhydride, isophthalic acid, terephthalic acid, adipic acid, and succinic acid; And / or, the acrylate crosslinking agent includes at least one of isooctyl acrylate, methyl methacrylate, butyl acrylate, soybean oil epoxidized acrylate, hydroxyethyl methacrylate, butyl methacrylate, and isobornyl methacrylate.

8. The unsaturated polyester according to claim 1, characterized in that, The unsaturated polyester has a tensile strength of not less than 29.6 MPa, a flexural strength of not less than 42.9 MPa, and a total volume shrinkage rate of not more than 3.0%.

9. A method for preparing the unsaturated polyester according to any one of claims 1-8, characterized in that, Includes the following steps: 1) The first mixture, including unsaturated dicarboxylic acid, saturated dicarboxylic acid, and polyol, is reacted at 150-180℃ for 0.5-2h, and then heated to 190-210℃ for high-temperature treatment to obtain a second mixture with an acid value of less than 50mg KOH / g. 2) After cooling the second mixture to 120-150℃, vacuum cooling treatment is performed. When the acid value is less than 10mg KOH / g and the temperature is not higher than 70℃, acrylate crosslinking agent and polymerization inhibitor are added to carry out polymerization reaction to obtain the unsaturated polyester.

10. The preparation method according to claim 9, characterized in that, It also includes the addition of a monohydric alcohol during the high-temperature treatment process, comprising the following steps: A first mixture comprising an unsaturated dicarboxylic acid, a saturated dicarboxylic acid, and a polyol is reacted at 150-180℃ for 0.5-2 hours, and then heated to 190-210℃ for high-temperature treatment. When the acid value of the first mixture is less than 300 mg KOH / g, a monohydric alcohol is added, and the high-temperature treatment is continued to obtain a second mixture with an acid value less than 50 mg KOH / g. Preferably, the unsaturated dicarboxylic acid comprises 11-93 parts by weight, the saturated dicarboxylic acid comprises 29-135 parts by weight, the polyol comprises 90-130 parts by weight, the acrylate crosslinking agent comprises 64-230 parts by weight, and the polymerization inhibitor comprises 0.04-0.2 parts by weight.

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