A saturated polyester copolymer, a method for preparing the same, and an application thereof

Abstract

The application discloses a kind of saturated polyester copolymer and its preparation method and application, belong to polymer material technical field.The preparation raw material of saturated polyester copolymer provided by the application includes: compound a, compound b, compound c, polyol, catalyst;Still include polyacid and / or polyacid anhydride;Compound a is compound b is compound c is The structure component of carbon ring common carbon atom is introduced in saturated polyester copolymer in the application, i.e.compound a and compound b, can realize the more orderly distribution of space group in chain segment, not only the adhesion of various substrates is significantly improved, and coating shrinkage is significantly reduced, in addition, hydroquinone or similar hydroquinone structure is also introduced simultaneously, effectively improve the heat resistance of polyester chain segment, and the saturated polyester copolymer of the application is used to prepare in-mold injection decorating ink, can effectively meet the performance requirements of in-mold injection process.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a saturated polyester copolymer, its preparation method and application. Background Technology

[0002] In-Mold Decoration (IMD) technology is a new technology that replaces painting and electroplating processes for plastic products. It involves placing a sheet of material into a mold cavity for injection molding. The injection resin bonds with a printed ink layer on the back of the sheet, with the ink layer positioned between the sheet and the injection-molded resin. The resin and sheet then bond together and cure to form a single, unified product. IMD products have a hardened transparent film on the surface, an ink pattern layer in the middle, and an injection-molded layer on the back. IMD technology increases design freedom; the patterns and colors are embedded within the plastic layers, improving wear resistance and maintaining vibrant colors for a long time.

[0003] In IMD (In-Metal Discharge) technology, IMD inks, as key materials, require high performance. After curing, the inks must have excellent elongation and high-temperature resistance. The resins used in IMD inks need to possess good temperature resistance, tensile flexibility, adhesion, surface hardness, impact resistance, and low shrinkage.

[0004] In the IMD process, plastic parts vary in shape and size, and thermal shrinkage and stress changes occur before and after molding. Currently, IMD inks generally suffer from unstable adhesion to optical coatings and poor versatility. Their high-temperature resistance and toughness are insufficient, failing to meet the performance indicators of the IMD process. Conventional linear or hyperbranched polyesters have not yet met the resin requirements for IMD inks. Summary of the Invention

[0005] In order to overcome at least one of the problems existing in the prior art, one of the objectives of the present invention is to provide a saturated polyester copolymer with good temperature resistance, tensile flexibility, adhesion, surface hardness, impact resistance and low shrinkage, and is particularly suitable for preparing inks for in-mold decoration (IMD).

[0006] A second objective of this invention is to provide a method for preparing the above-mentioned saturated polyester copolymer.

[0007] A third objective of this invention is to provide an application of the above-mentioned saturated polyester copolymer.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A first aspect of the present invention provides a saturated polyester copolymer, wherein the raw materials for preparing the saturated polyester copolymer include: compound a, compound b, compound c, polyol, and catalyst; and further include polybasic acid and / or polybasic acid anhydride;

[0010] The chemical formula of compound a is shown in Formula 1:

[0011]

[0012] The chemical formula of compound b is shown in Formula 2:

[0013]

[0014] The chemical formula of compound c is shown in Formula 3:

[0015]

[0016] In Formula 1, each R1 is independently selected from hydroxyl, carboxyl, or amino groups, and at least one R1 is hydroxyl; n1 ≥ 1 and n1 is an integer;

[0017] In Formula 2, each R2 is independently selected from hydroxyl, carboxyl, or amino groups, and at least one R2 is hydroxyl; each X is independently selected from C1 to C10 alkyl groups; 1 ≤ n2 ≤ 5 and n2 is an integer;

[0018] In Formula 3, each R3 is independently selected from hydroxyl, carboxyl or amino, and at least one R3 is hydroxyl; n3≥2 and n3 is an integer.

[0019] In existing polyester materials, some directly use monomers containing only alicyclic groups and monomers containing only benzene ring groups as synthetic raw materials, resulting in unevenness of the synthesized polyester chain segments. Others use conventional aliphatic or monobenzene ring aromatic polybasic acids or alcohols to synthesize polyesters, which have poor flexibility and heat resistance, making them difficult to adapt to the process characteristics of IMD inks. Compared with existing polyester materials, this invention introduces structural components with shared carbon atoms in carbon rings into the polyester copolymer, namely compounds a and b, which can achieve a more ordered distribution of spatial groups in the chain segments. This not only significantly improves the adhesion to various substrates but also significantly reduces coating shrinkage, effectively meeting the performance requirements of in-mold injection molding. Combined with compound c with an alicyclic structure, as well as polybasic acids (anhydrides) and polyols, the resulting saturated polyester copolymer has good temperature resistance, tensile flexibility, adhesion, surface hardness, impact resistance, and low shrinkage, making it particularly suitable for preparing inks for in-mold decoration (IMD).

[0020] Preferably, in Formula 1, each R1 is independently selected from hydroxyl or amino groups, and at least one R1 is a hydroxyl group; more preferably, in Formula 1, each R1 is equally selected from hydroxyl or amino groups, and compound a is a mixture of different Formula 1 compounds, wherein at least one R1 of compound a is selected from a hydroxyl group; even more preferably, in Formula 1, each R1 is equally selected from a hydroxyl group.

[0021] Preferably, when compound a is a mixture of compounds of different formula 1, and part of R1 is selected from hydroxyl groups and the other part of R1 is selected from amino groups, the molar content of hydroxyl groups in compound a is greater than the molar content of amino groups.

[0022] Preferably, in Formula 1, n1 is 1 to 10 and is an integer; more preferably, in Formula 1, n1 is 1 to 5 and is an integer; for example, n1 is 1, 2, 3, 4 or 5; even more preferably, in Formula 1, n1 is 1.

[0023] In some specific embodiments of the present invention, compound a is selected from 2-methylspirocyclic[3.5]nonane-2,7-diol.

[0024] Preferably, compound a accounts for 0.5 to 40 wt% of the total mass of the raw materials for preparing the polyester copolymer; more preferably, compound a accounts for 0.8 to 30 wt% of the total mass of the raw materials for preparing the polyester copolymer; even more preferably, compound a accounts for 1 to 20 wt% of the total mass of the raw materials for preparing the polyester copolymer; non-limiting specific examples include 3 wt%, 5 wt%, 8 wt%, 10 wt%, 13 wt%, 15 wt%, or 18 wt%.

[0025] Preferably, in Formula 2, each R2 is independently selected from hydroxyl or amino groups, and at least one R2 is hydroxyl; more preferably, in Formula 2, each R2 is equally selected from hydroxyl or amino groups, and compound b is a mixture of different compounds of Formula 2, wherein at least one compound of Formula 2 has an R2 selected from hydroxyl; even more preferably, in Formula 2, each R2 is equally selected from hydroxyl.

[0026] Preferably, when compound b is a mixture of compounds of different formula 2, and part of R2 is selected from hydroxyl groups and the other part of R2 is selected from amino groups, the molar content of hydroxyl groups in compound b is greater than the molar content of amino groups.

[0027] Preferably, in Formula 2, each X is independently selected from C1 to C8 alkyl; more preferably, in Formula 2, each X is independently selected from C1 to C5 alkyl; even more preferably, in Formula 2, each X is independently selected from methyl or ethyl.

[0028] Preferably, in Equation 2, 1 ≤ n2 ≤ 3 and n2 is an integer; for example, n2 is 1, 2 or 3; more preferably, in Equation 2, n2 is 1.

[0029] In some specific embodiments of the present invention, compound b is selected from 4,8-tricyclo[5.2.1.O2,7]decanediethanol.

[0030] Preferably, the compound b accounts for 0.5 to 60 wt% of the total mass of the raw materials for preparing the polyester copolymer; more preferably, the compound b accounts for 1 to 50 wt% of the total mass of the raw materials for preparing the polyester copolymer; even more preferably, the compound b accounts for 5 to 40 wt% of the total mass of the raw materials for preparing the polyester copolymer; non-limiting specific examples include 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, or 35 wt%.

[0031] Preferably, in Formula 3, each R3 is independently selected from hydroxyl or amino groups, and at least one R3 is hydroxyl; more preferably, in Formula 3, each R3 is equally selected from hydroxyl or amino groups, and compound c is a mixture of different Formula 3 compounds, wherein at least one R3 of compound c is selected from hydroxyl; even more preferably, in Formula 3, each R3 is equally selected from hydroxyl.

[0032] Preferably, when compound c is a mixture of compounds of different formula 3, and part of R3 is selected from hydroxyl groups and the other part of R3 is selected from amino groups, the molar content of hydroxyl groups in compound c is greater than the molar content of amino groups.

[0033] Preferably, in Formula 3, n3 is 2 to 10 and n3 is an integer; more preferably, in Formula 3, n3 is 2 to 5; specific examples include n3 being 2, 3, 4 or 5; even more preferably, in Formula 3, n3 is 2.

[0034] In some specific embodiments of the present invention, compound c is selected from 4,4'-dihydroxydicyclohexane.

[0035] Preferably, compound c accounts for 0.5 to 40 wt% of the total mass of the raw materials for preparing the polyester copolymer; more preferably, compound c accounts for 0.8 to 30 wt% of the total mass of the raw materials for preparing the polyester copolymer; even more preferably, compound c accounts for 1 to 20 wt% of the total mass of the raw materials for preparing the polyester copolymer; non-limiting specific examples include 3 wt%, 5 wt%, 8 wt%, 10 wt%, 13 wt%, 15 wt%, or 18 wt%.

[0036] Preferably, the mass ratio of compound b is greater than the mass ratio of compound a; more preferably, the mass ratio of compound b to compound a is 1:(0.1 to 0.9).

[0037] Preferably, the mass ratio of compound b is greater than the mass ratio of compound c; more preferably, the mass ratio of compound b to compound c is 1:(0.1 to 0.9).

[0038] Preferably, the polyol comprises a first polyol, or a combination of a first polyol and a second polyol; the first polyol comprises a polyol containing C6 to C20 aryl and / or ether groups; the second polyol comprises C2 to C20 aliphatic polyols, C5 to C20 alicyclic polyacids, or combinations thereof.

[0039] Preferably, the first polyol comprises a polyol containing C6-C20 aryl and ether groups; more preferably, the first polyol comprises a polyol containing phenyl and ether groups; even more preferably, the first polyol comprises hydroquinone dihydroxyethyl ether, hydroxyethylated bisphenol A, or a combination thereof; more preferably, the first polyol is selected from hydroquinone dihydroxyethyl ether, or selected from hydroquinone dihydroxyethyl ether and hydroxyethylated bisphenol A.

[0040] Furthermore, in addition to introducing structural components that share carbon atoms in carbon rings, a first polyol with a specific hydroquinone or hydroquinone-like structure is also used. By introducing hydroquinone or hydroquinone-like structures, the heat resistance of the polyester chain segments is effectively improved, which helps to suppress the thermal degradation of the ink layer during the in-mold injection molding process and maintain the overall stability of the ink layer in the IMD process.

[0041] Preferably, the second polyol comprises C2-C15 aliphatic polyols, C5-C15 alicyclic polyacids, or combinations thereof; more preferably, the second polyol comprises at least one selected from neopentyl glycol, ethylene glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, hexadecanediol, trimethylolpropane, or trimethylolethane; even more preferably, the second polyol comprises at least one selected from neopentyl glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, or trimethylolpropane; more preferably, the second polyol comprises neopentyl glycol, 2-methyl-1,3-propanediol, or combinations thereof.

[0042] Preferably, the polybasic acid includes at least one of C6-C20 aromatic polybasic acid, C2-C20 fatty polybasic acid, or C5-C20 alicyclic polybasic acid; more preferably, the polybasic acid includes at least one of C6-C15 aromatic polybasic acid, C5-C15 fatty polybasic acid, or C7-C15 alicyclic polybasic acid.

[0043] Preferably, the polyacid includes at least one selected from adipic acid, octanoic acid, sebacic acid, dodecanoic acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, or trimellitic acid; more preferably, the polyacid includes at least one selected from adipic acid, octanoic acid, sebacic acid, terephthalic acid, isophthalic acid, or trimellitic acid; even more preferably, the polyacid includes at least one selected from adipic acid, terephthalic acid, isophthalic acid, or trimellitic acid.

[0044] Preferably, the polyacid anhydride includes at least one of C6-C20 aromatic polyacid anhydride, C2-C20 fatty polyacid anhydride, or C5-C20 alicyclic polyacid anhydride; more preferably, the polyacid anhydride includes at least one of C6-C15 aromatic polyacid anhydride, C5-C15 fatty polyacid anhydride, or C7-C15 alicyclic polyacid anhydride.

[0045] Preferably, the polybasic acid anhydride includes at least one selected from adipic anhydride, octanoic anhydride, sebacic anhydride, dodecanoic anhydride, cyclohexanedicarboxylic anhydride, or trimellitic anhydride; more preferably, the polybasic acid anhydride includes at least one selected from adipic anhydride, octanoic anhydride, sebacic anhydride, dodecanoic anhydride, or trimellitic anhydride; even more preferably, the polybasic acid anhydride includes adipic anhydride, trimellitic anhydride, or a combination thereof.

[0046] Preferably, the total molar ratio of the compound a, compound b, compound c, and polyol to the total molar ratio of the polyacid and / or polyacid anhydride is (0.9–3.5):1; more preferably, the total molar ratio of the compound a, compound b, compound c, and polyol to the total molar ratio of the polyacid and / or polyacid anhydride is (0.9–3):1; even more preferably, the total molar ratio of the compound a, compound b, compound c, and polyol to the total molar ratio of the polyacid and / or polyacid anhydride is (0.9–2.5):1; non-limiting specific examples include 1:1, 1.5:1, or 2:1.

[0047] Preferably, the catalyst comprises at least one of a tin-based catalyst, an antimony-based catalyst, or a titanium-based catalyst; more preferably, the catalyst comprises a tin-based catalyst, a titanium-based catalyst, or a combination thereof.

[0048] Preferably, the number-average molecular weight of the saturated polyester copolymer is 5–50 kDa; more preferably, the number-average molecular weight of the saturated polyester copolymer is 7–45 kDa; even more preferably, the number-average molecular weight of the saturated polyester copolymer is 9–40 kDa; more preferably, the number-average molecular weight of the saturated polyester copolymer is 10–35 kDa. Non-limiting specific examples include 12 kDa, 15 kDa, 18 kDa, 20 kDa, 25 kDa, or 30 kDa.

[0049] Preferably, the glass transition temperature of the saturated polyester copolymer is -20 to 70°C; more preferably, the glass transition temperature of the saturated polyester copolymer is -10 to 60°C; even more preferably, the glass transition temperature of the saturated polyester copolymer is 0 to 55°C; more preferably, the glass transition temperature of the saturated polyester copolymer is 10 to 50°C. Non-limiting specific examples include 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, or 45°C.

[0050] Preferably, the acid value of the saturated polyester copolymer is 1-20 mg KOH / g; more preferably, the acid value of the saturated polyester copolymer is 2-15 mg KOH / g; even more preferably, the acid value of the saturated polyester copolymer is 3-10 mg KOH / g. Non-limiting specific examples include 3.5 mg KOH / g, 4 mg KOH / g, 5 mg KOH / g, 6 mg KOH / g, 7 mg KOH / g, 8 mg KOH / g, or 9 mg KOH / g.

[0051] Preferably, the hydroxyl value of the saturated polyester copolymer is 10–50 mg KOH / g; more preferably, the hydroxyl value of the saturated polyester copolymer is 3–45 mg KOH / g; even more preferably, the hydroxyl value of the saturated polyester copolymer is 5–40 mg KOH / g. Non-limiting specific examples include 15 mg KOH / g, 18 mg KOH / g, 20 mg KOH / g, 22 mg KOH / g, 25 mg KOH / g, 30 mg KOH / g, or 35 mg KOH / g.

[0052] A second aspect of the present invention provides a method for preparing the saturated polyester copolymer described in the first aspect of the present invention, comprising the following steps:

[0053] S1. Compound a, compound c, polyol, a portion of compound b, polybasic acid and / or polybasic acid anhydride, and catalyst are mixed and subjected to a first polymerization reaction in a protective gas atmosphere to obtain a first polymer.

[0054] S2. Add the balance of compound b, polybasic acid and / or polybasic acid anhydride to the first polymer, and carry out a second polymerization reaction in a protective gas atmosphere to obtain the second polymer.

[0055] S3. Add the remaining catalyst to the second polymer and carry out a vacuum polycondensation reaction to obtain the saturated polyester copolymer.

[0056] Preferably, the temperature of the first polymerization reaction is 200–260°C; more preferably, the temperature of the first polymerization reaction is 220–240°C.

[0057] Preferably, the temperature of the second polymerization reaction is 200–260°C; more preferably, the temperature of the second polymerization reaction is 220–240°C.

[0058] Preferably, there is a heating process between the second polymerization reaction and the vacuum polycondensation reaction.

[0059] Preferably, the temperature of the vacuum polycondensation reaction is 220–280°C; more preferably, the temperature of the vacuum polycondensation reaction is 230–260°C.

[0060] Preferably, the reaction endpoint of the first polymerization reaction is when the acid value of the first polymer is ≤20mgKOH / g; more preferably, the reaction endpoint of the first polymerization reaction is when the acid value of the first polymer is ≤18mgKOH / g; even more preferably, the reaction endpoint of the first polymerization reaction is when the acid value of the first polymer is ≤15mgKOH / g.

[0061] Preferably, the reaction endpoint of the second polymerization reaction is when the acid value of the second polymer is ≤35mgKOH / g; more preferably, the reaction endpoint of the second polymerization reaction is when the acid value of the second polymer is ≤30mgKOH / g; even more preferably, the reaction endpoint of the second polymerization reaction is when the acid value of the second polymer is ≤28mgKOH / g.

[0062] Preferably, the vacuum degree of the vacuum polycondensation reaction is ≤600Pa.

[0063] A third aspect of the present invention provides an ink for in-mold decoration (IMD), comprising the saturated polyester copolymer described in the first aspect of the present invention.

[0064] Preferably, the in-mold decorative ink further includes a curing agent, an amino resin, or a combination thereof.

[0065] Preferably, the curing agent is selected from isocyanate compounds; more preferably, the isocyanate compound includes at least one of diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, di(isocyanate methyl)cyclohexane, cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, or the corresponding blocked isocyanate compound.

[0066] Preferably, the amino resin includes at least one of methyl etherified amino resin, diethyl etherified amino resin, propyl etherified amino resin, or butyl etherified amino resin; more preferably, the amino resin includes methyl etherified amino resin, butyl etherified amino resin, or a combination thereof.

[0067] Preferably, the methyl etherified amino resin includes partially methyl etherified amino resin, fully methyl etherified amino resin, or a combination thereof.

[0068] The saturated polyester copolymer of the present invention can be used as the main binder for preparing inks for in-mold decoration (IMD). It can form a coating in a single-component form, or it can undergo a crosslinking reaction with components such as isocyanate compounds and / or amino resins to obtain a cured coating. It can meet the excellent coating performance requirements of IMD inks, such as temperature resistance, tensile flexibility, adhesion, surface hardness, impact resistance, and low shrinkage.

[0069] The beneficial effects of this invention are as follows: By introducing structural components, namely compounds a and b, with shared carbon atoms in carbon rings into the saturated polyester copolymer, a more ordered distribution of spatial groups in the chain segments can be achieved. This not only significantly improves the adhesion to various substrates but also significantly reduces coating shrinkage. In addition to introducing structural components with shared carbon atoms in carbon rings, this invention also simultaneously introduces hydroquinone or hydroquinone-like structures, effectively improving the heat resistance of the polyester chain segments. When the saturated polyester copolymer of this invention is used to prepare in-mold decorative inks, it can effectively meet the performance requirements of the in-mold injection molding process, inhibit the thermal degradation of the ink layer during the in-mold injection molding process, and maintain the overall stability of the ink layer in the in-mold decorative process.

[0070] Specifically, compared with the prior art, the present invention has the following advantages:

[0071] 1. This invention introduces structural components with shared carbon atoms in carbon rings through compounds a and b, which effectively improves the orderly distribution of polyester segments. Furthermore, it employs a first polyol with a specific structure to introduce hydroquinone or hydroquinone-like structures, which effectively enhances the heat resistance of polyester segments. This helps to suppress the thermal degradation of the ink layer during in-mold injection molding and maintain the overall stability of the ink layer in the IMD process.

[0072] 2. This invention changes the existing application method of IMD inks, which uses multiple types of adhesive resins to achieve the performance requirements of the ink layer. The saturated polyester copolymer of this invention, as the main film-forming material, can form a coating in the form of a single adhesive, or it can be combined with isocyanate curing agents and / or amino resins to form a coating. Moreover, the prepared ink coating for IMD can overcome the technical bottleneck of the ink layer being difficult to adhere to and easy to fall off the plastic substrate, significantly improve the stable adhesion performance of the coating in the IMD process, and further improve the comprehensive performance of the coating such as temperature resistance, tensile flexibility, adhesion, surface hardness, impact resistance and low shrinkage. Detailed Implementation

[0073] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described herein are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments and comparative examples can be obtained from conventional commercial sources or by existing known methods.

[0074] Example 1

[0075] This example provides a saturated polyester copolymer prepared from the following raw materials: 2-methylspirocyclic [3.5]nonane-2,7-diol, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, 4,4'-dihydroxydicyclohexane, 2-methyl-1,3-propanediol, neopentyl glycol, hydroquinone dihydroxyethyl ether, terephthalic acid, isophthalic acid, adipic acid, and a tin-based catalyst. Specific amounts are shown in Table 1.

[0076] The preparation method of the saturated polyester copolymer in this example specifically includes the following steps (the raw materials and amounts used in each step are shown in Table 1):

[0077] (1) In a reactor equipped with a stirrer, thermometer, reflux condenser and nitrogen gas, the raw materials required for the first step reaction are added to the reactor according to the application amounts shown in Table 1, including 2-methylspirocyclic[3.5]nonane-2,7-diol, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, 4,4'-dihydroxydicyclohexane, 2-methyl-1,3-propanediol, neopentyl glycol, hydroquinone dihydroxyethyl ether, terephthalic acid, isophthalic acid, adipic acid and tin catalyst. Under the protective atmosphere of nitrogen gas, the temperature is gradually increased and the reaction is carried out at 220-240°C for 4-6 hours until the acid value of the system drops below 20 mg KOH / g.

[0078] (2) Keeping the reaction conditions of step (1), add the raw materials required for the second step reaction according to the amount shown in Table 1, including 4,8-tricyclo[5.2.1.O2,7]decanediethanol and isophthalic acid, and react until the acid value of the system drops below 30 mg KOH / g.

[0079] (3) Add tin catalyst according to the amount shown in Table 1, and perform vacuum polycondensation at 230-260℃ (vacuum degree ≤600Pa) until the target viscosity is reached to obtain saturated polyester copolymer CP1.

[0080] Example 2

[0081] This example provides a saturated polyester copolymer prepared from the following raw materials: 2-methylspirocyclic [3.5]nonane-2,7-diol, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, 4,4'-dihydroxydicyclohexane, 2-methyl-1,3-propanediol, neopentyl glycol, hydroxyethylated bisphenol A, terephthalic acid, isophthalic acid, adipic acid, and antimony catalyst. Specific amounts are shown in Table 1.

[0082] The preparation method of the saturated polyester copolymer in this example specifically includes the following steps (the raw materials and amounts used in each step are shown in Table 1):

[0083] (1) In a reactor equipped with a stirrer, thermometer, reflux condenser and nitrogen gas, the raw materials required for the first step reaction are added to the reactor according to the application amounts shown in Table 1, including 2-methylspirocyclic[3.5]nonane-2,7-diol, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, 4,4'-dihydroxydicyclohexane, 2-methyl-1,3-propanediol, neopentyl glycol, hydroxyethylated bisphenol A, terephthalic acid, isophthalic acid and antimony catalyst. Under the protective atmosphere of nitrogen gas, the temperature is gradually increased and the reaction is carried out at 220-240°C for 4-6 hours until the acid value of the system drops below 18 mg KOH / g.

[0084] (2) Keeping the reaction conditions of step (1), add the raw materials required for the second step reaction according to the amount shown in Table 1, including 4,8-tricyclo[5.2.1.O2,7]decanediethanol and adipic acid, and react until the acid value of the system drops below 28 mg KOH / g.

[0085] (3) Add antimony catalyst according to the dosage shown in Table 1, and carry out vacuum polycondensation at 230-260℃ (vacuum degree ≤600Pa) until the target viscosity is reached to obtain saturated polyester copolymer CP2.

[0086] Example 3

[0087] This example provides a saturated polyester copolymer prepared from the following raw materials: 2-methylspirocyclic [3.5]nonane-2,7-diol, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, 4,4'-dihydroxydicyclohexane, 2-methyl-1,3-propanediol, neopentyl glycol, hydroquinone dihydroxyethyl ether, terephthalic acid, isophthalic acid, adipic acid, cyclohexanedicarboxylic acid, and a titanium catalyst. Specific amounts are shown in Table 1.

[0088] The preparation method of the saturated polyester copolymer in this example specifically includes the following steps (the raw materials and amounts used in each step are shown in Table 1):

[0089] (1) In a reactor equipped with a stirrer, thermometer, reflux condenser and nitrogen gas, the raw materials required for the first step reaction are added to the reactor according to the application amounts shown in Table 1, including 2-methylspirocyclic[3.5]nonane-2,7-diol, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, 4,4'-dihydroxydicyclohexane, 2-methyl-1,3-propanediol, neopentyl glycol, hydroquinone dihydroxyethyl ether, terephthalic acid, isophthalic acid, adipic acid and titanium catalyst. Under the protective atmosphere of nitrogen gas, the temperature is gradually increased and the reaction is carried out at 220-240°C for 4-6 hours until the acid value of the system drops below 15 mg KOH / g.

[0090] (2) While maintaining the reaction conditions of step (1), add the raw materials required for the second step reaction according to the amount shown in Table 1, including 4,8-tricyclo[5.2.1.O2,7]decanediethanol and cyclohexanedicarboxylic acid, and react until the acid value of the system drops below 23 mg KOH / g.

[0091] (3) Add titanium catalyst according to the dosage shown in Table 1, and perform vacuum polycondensation at 230-260℃ (vacuum degree ≤600Pa) until the target viscosity is reached to obtain saturated polyester copolymer CP3.

[0092] Example 4

[0093] This example provides a saturated polyester copolymer prepared from the following raw materials: 2-methylspirocyclic [3.5]nonane-2,7-diol, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, 4,4'-dihydroxydicyclohexane, 2-methyl-1,3-propanediol, neopentyl glycol, hydroxyethylated bisphenol A, terephthalic acid, isophthalic acid, adipic acid, trimellitic anhydride, and a titanium catalyst. Specific amounts are shown in Table 1.

[0094] The preparation method of the saturated polyester copolymer in this example specifically includes the following steps (the raw materials and amounts used in each step are shown in Table 1):

[0095] (1) In a reactor equipped with a stirrer, thermometer, reflux condenser and nitrogen gas, the raw materials required for the first step reaction are added to the reactor according to the application amounts shown in Table 1, including 2-methylspirocyclic[3.5]nonane-2,7-diol, 4,8-tricyclo[5.2.1.O2,7]decanediethanol, 4,4'-dihydroxydicyclohexane, 2-methyl-1,3-propanediol, neopentyl glycol, hydroxyethylated bisphenol A, terephthalic acid, isophthalic acid, adipic acid, trimellitic anhydride and titanium catalyst. Under the protective atmosphere of nitrogen gas, the temperature is gradually increased and the reaction is carried out at 220-240°C for 4-6 hours until the acid value of the system drops below 18 mg KOH / g.

[0096] (2) Keeping the reaction conditions of step (1), add the raw materials required for the second step reaction according to the amount shown in Table 1, including 4,8-tricyclo[5.2.1.O2,7]decanediethanol, isophthalic acid and adipic acid, and react until the acid value of the system drops below 26 mg KOH / g.

[0097] (3) Add titanium catalyst according to the dosage shown in Table 1, and perform vacuum polycondensation at 230-260℃ (vacuum degree ≤600Pa) until the target viscosity is reached to obtain saturated polyester copolymer CP4.

[0098] Comparative Example 1

[0099] This example provides a saturated polyester copolymer prepared from the following raw materials: 2-methyl-1,3-propanediol, neopentyl glycol, hydroxyethylated bisphenol A, terephthalic acid, isophthalic acid, adipic acid, and a tin-based catalyst. Specific amounts are shown in Table 1.

[0100] The preparation method of the saturated polyester copolymer in this example specifically includes the following steps:

[0101] In a reactor equipped with a stirrer, thermometer, reflux condenser, and nitrogen purging, the raw materials, including 2-methyl-1,3-propanediol, neopentyl glycol, hydroxyethylated bisphenol A, terephthalic acid, isophthalic acid, adipic acid, and a tin-based catalyst, were added according to the application amounts shown in Table 1. Under a protective atmosphere of nitrogen purging, the temperature was gradually increased and maintained at 230–250°C for 6–7 hours, until the acid value of the system decreased to below 25 mg KOH / g. Vacuum polycondensation (vacuum degree ≤ 700 Pa) was then performed until the target viscosity was reached, yielding a saturated polyester copolymer CP5.

[0102] Comparative Example 2

[0103] This example provides a saturated polyester copolymer prepared from the following raw materials: 2-methyl-1,3-propanediol, neopentyl glycol, hydroquinone dihydroxyethyl ether, trimellitic anhydride, terephthalic acid, isophthalic acid, adipic acid, and a titanium catalyst. Specific amounts are shown in Table 1.

[0104] The preparation method of the saturated polyester copolymer in this example specifically includes the following steps:

[0105] In a reactor equipped with a stirrer, thermometer, reflux condenser, and nitrogen purging, the raw materials, including 2-methyl-1,3-propanediol, neopentyl glycol, hydroquinone dihydroxyethyl ether, trimellitic anhydride, terephthalic acid, isophthalic acid, adipic acid, and a titanium catalyst, were added according to the application amounts shown in Table 1. Under a protective atmosphere of nitrogen purging, the temperature was gradually increased and maintained at 230–250°C for 6–7 hours, until the acid value of the system decreased to below 25 mg KOH / g. Vacuum polycondensation (vacuum degree ≤700 Pa) was then performed until the target viscosity was reached, yielding a saturated polyester copolymer CP6.

[0106] Table 1. Raw materials and their quantities for each step in Examples 1-4 and Comparative Examples 1-2.

[0107]

[0108]

[0109] The performance parameters of the saturated polyester copolymers prepared in Examples 1-4 and Comparative Examples 1-2 were tested, including acid value, hydroxyl value, number-average molecular weight and glass transition temperature. The results are shown in Table 2.

[0110] Table 2 Performance indicators of saturated polyester copolymers in Examples 1-4 and Comparative Examples 1-2

[0111]

[0112] Application Examples 1-4 and Comparative Examples 1-2

[0113] An IMD ink was prepared by using the saturated polyester copolymers obtained in Examples 1-4 and Comparative Examples 1-2 as the main resin, and combining them with other raw materials to obtain the IMD inks of Application Examples 1-4 and Application Comparative Examples 1-2. The specific raw material composition is shown in Table 3.

[0114] Table 3. Composition of IMD ink raw materials in Application Examples 1-4 and Comparative Examples 1-2.

[0115] Components Function mass percentage Saturated polyester copolymers of Examples 1-4 and Comparative Examples 1-2 Main resin 38.0％ Duranate TKA-90SB curing agent 3.0％ Takenate 500 curing agent 0.8％ DBE solvent 32.0％ Cyclohexanone solvent 8.0％ Isophorone diluent 7.0％ carbon black pigment 8.0％ TEGO 370 Leveling agent 0.2％ BYK 163 dispersant 2.0％ DAVY DS P111 Accelerator 1.0％

[0116] The IMD inks prepared in Application Examples 1-4 and Comparative Examples 1-2 were screen-printed onto PC / PMMA / PET films. After heat treatment (50-80℃×1h), an ink-cured coating was formed. After further printing of adhesive, the coating was dried, and finally, IMD molding and injection molding were performed to obtain IMD plastic parts. The performance of the ink coating on the film and the ink coating after IMD process was tested, and the test results are shown in Table 4.

[0117] Table 4 shows the performance of IMD inks in Application Examples 1-4 and Comparative Examples 1-2.

[0118]

[0119] As shown in Table 4, the IMD inks of Application Examples 1-4 of this invention exhibit good room temperature adhesion performance, as well as good temperature resistance and stable adhesion performance. In contrast, the IMD inks of Comparative Examples 1-2 show poor room temperature adhesion performance, especially poor temperature resistance and stable adhesion performance, making it difficult to meet the requirements of the IMD process. Therefore, the IMD ink coatings prepared using the saturated polyester copolymers of Examples 1-4 of this invention can overcome the technical bottleneck of difficult adhesion and easy peeling of ink layers to plastic substrates, significantly improve the stable adhesion performance of the coating during the IMD process, and further enhance the comprehensive properties of the coating in terms of temperature resistance, tensile flexibility, adhesion, surface hardness, impact resistance, and low shrinkage.

Claims

1. A saturated polyester copolymer characterized in that, The preparation raw materials of the saturated polyester copolymer include: compound a, compound b, compound c, polyhydric alcohol, catalyst; further include polybasic acid and / or polybasic anhydride; The chemical formula of the compound a is shown as formula 1: (Formula 1); The chemical formula of the compound b is shown as formula 2: (Formula 2); The chemical formula of the compound c is shown as formula 3: (Formula 3); In formula 1, each R1 is independently selected from hydroxyl, carboxyl or amino, and at least one R1 is hydroxyl; n1 is greater than or equal to 1 and is an integer; In formula 2, each R2 is independently selected from hydroxyl, carboxyl or amino, and at least one R2 is hydroxyl; each X is independently selected from C1-C10 alkyl; 1 is less than or equal to n2 which is less than or equal to 5 and is an integer; In formula 3, each R3 is independently selected from hydroxyl, carboxyl or amino, and at least one R3 is hydroxyl; n3 is greater than or equal to 2 and is an integer; The saturated polyester copolymer is prepared by a method comprising the following steps: S1, mixing compound a, compound c, polyhydric alcohol, part of compound b, polybasic acid and / or polybasic anhydride, and catalyst, and performing first polymerization reaction in a protective gas atmosphere to obtain a first polymer; S2, adding the rest of compound b, polybasic acid and / or polybasic anhydride into the first polymer, and performing second polymerization reaction in a protective gas atmosphere to obtain a second polymer; S3, adding the rest of catalyst into the second polymer, and performing vacuum polycondensation reaction to obtain the saturated polyester copolymer.

2. The saturated polyester copolymer of claim 1, wherein In formula 1, each R1 is independently selected from hydroxyl or amino, and at least one R1 is hydroxyl; And / or, in formula 1, n1 is an integer between 1 and 10; And / or, in formula 2, each R2 is independently selected from hydroxyl or amino, and at least one R2 is hydroxyl; And / or, in formula 2, n2 is an integer between 1 and 3; And / or, in formula 3, each R3 is independently selected from hydroxyl or amino, and at least one R3 is hydroxyl; And / or, in formula 3, n3 is an integer between 2 and 10.

3. The saturated polyester copolymer of claim 1, wherein, The polyhydric alcohol includes a first polyhydric alcohol, or a combination of the first polyhydric alcohol and a second polyhydric alcohol; the first polyhydric alcohol includes a polyhydric alcohol containing C6-C20 aryl and / or ether group; the second polyhydric alcohol includes C2-C20 aliphatic polyhydric alcohol, C5-C20 alicyclic polyhydric acid, or a combination thereof; And / or, the polybasic acid includes at least one of C6-C20 aromatic polybasic acid, C2-C20 aliphatic polybasic acid, or C5-C20 alicyclic polybasic acid; And / or, the polybasic anhydride includes at least one of C6-C20 aromatic polybasic anhydride, C2-C20 aliphatic polybasic anhydride, or C5-C20 alicyclic polybasic anhydride; And / or, the catalyst includes at least one of tin-based catalyst, antimony-based catalyst, or titanium-based catalyst.

4. The saturated polyester copolymer of claim 3, wherein, The first polyhydric alcohol includes hydroquinone dihydroxyethyl ether, hydroxyethylated bisphenol A, or a combination thereof; And / or, the second polyhydric alcohol includes at least one of neopentyl glycol, ethylene glycol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanedimethanol, hexadecanediol, trimethylolpropane, or trimethylolethane. And / or, the polybasic acid comprises at least one of adipic acid, suberic acid, sebacic acid, dodecanedioic acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid or trimellitic acid; And / or, the polybasic anhydride comprises at least one of adipic anhydride, suberic anhydride, sebacic anhydride, dodecanedioic anhydride, cyclohexanedicarboxylic anhydride or trimellitic anhydride.

5. The saturated polyester copolymer according to any one of claims 1 to 4, characterized in that, The mass ratio of the compound a in the total amount of raw materials for preparing the polyester copolymer is 0.5-40%wt; And / or, the mass ratio of the compound b in the total amount of raw materials for preparing the polyester copolymer is 0.5-60%wt; And / or, the mass ratio of the compound c in the total amount of raw materials for preparing the polyester copolymer is 0.5-40%wt; And / or, the mass ratio of the compound b is greater than the mass ratio of the compound a; And / or, the mass ratio of the compound b is greater than the mass ratio of the compound c.

6. The saturated polyester copolymer according to any one of claims 1 to 4, characterized in that, The total amount of moles of the compound a, the compound b, the compound c and the polyhydric alcohol is in a ratio of (0.9-3.5):1 to the total amount of moles of the polybasic acid and / or the polybasic anhydride.

7. The saturated polyester copolymer according to any one of claims 1 to 4, characterized in that, The number average molecular weight of the saturated polyester copolymer is 5-50kDa; And / or, the glass transition temperature of the saturated polyester copolymer is -20-70℃; And / or, the acid value of the saturated polyester copolymer is 1-20mgKOH / g; And / or, the hydroxyl value of the saturated polyester copolymer is 10-50mgKOH / g.

8. A process for the preparation of a saturated polyester copolymer as claimed in any one of claims 1 to 7, characterised in that, The method comprises the following steps: S1, mixing the compound a, the compound c, the polyhydric alcohol, part of the compound b, the polybasic acid and / or the polybasic anhydride and a catalyst to carry out a first polymerization reaction in a protective gas atmosphere to obtain a first polymer; S2, adding the remaining compound b, the polybasic acid and / or the polybasic anhydride to the first polymer to carry out a second polymerization reaction in a protective gas atmosphere to obtain a second polymer; S3, adding the remaining catalyst to the second polymer to carry out a vacuum polycondensation reaction to obtain the saturated polyester copolymer.

9. The preparation method according to claim 8, characterized in that, The temperature of the first polymerization reaction is 200-260℃; And / or, the temperature of the second polymerization reaction is 200-260℃; And / or, the temperature of the vacuum polycondensation reaction is 220-280℃; And / or, the end point of the first polymerization reaction is that the acid value of the first polymer is ≤20mgKOH / g; And / or, the end point of the second polymerization reaction is that the acid value of the second polymer is ≤35mgKOH / g; And / or, the vacuum degree of the vacuum polycondensation reaction is ≤600Pa.

10. An ink for in-mold decoration, characterized by, The raw materials comprise the saturated polyester copolymer according to any one of claims 1-7.

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