A dimethyl decalin difunctional compound and its preparation method and application

Abstract

This invention relates to a dimethyl-bridged decahydronaphthalene difunctional compound, its preparation method, and its applications. The compound is a dimethyl-bridged decahydronaphthalene dicarboxylate, prepared from dimethyl-bridged octahydronaphthalene carboxylate as a starting material via a carbonylation reaction under the action of a catalyst system composed of bidentate organophosphorus ligands complexed with palladium. This compound possesses a highly rigid dinorbornene skeleton, which, when applied to polyester materials, can effectively increase the glass transition temperature of the polymer. Simultaneously, the saturated alicyclic skeleton it contains imparts high transparency and weather resistance to the polyester material. By optimizing the catalyst system and reaction conditions, the product content can reach 63%. The copolyester obtained by polycondensation of this compound with diols has a glass transition temperature of 103-112℃ and a light transmittance of 89-91%, exhibiting both good mechanical and processing properties, making it suitable for preparing highly transparent and heat-resistant polyester materials.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more particularly to a compound containing a dimethylbridged decahydronaphthalene difunctional group, its preparation method, and its application. Background Technology

[0002] In the field of high-temperature resistant polyesters, polyethylene naphthalate (PEN) is an important member of the polyester family. It is formed by the condensation polymerization of 2,6-naphthalenedicarboxylic acid or dimethyl 2,6-naphthalenedicarboxylic acid with ethylene glycol, and is a high-performance thermoplastic resin. The chemical structure of PEN is similar to that of polyethylene terephthalate (PET), but the difference lies in the molecular chain. In PEN, the more rigid naphthalene ring replaces the benzene ring in PET. This naphthalene ring structure gives PEN higher physical and mechanical properties, gas barrier properties, chemical stability, and resistance to heat, ultraviolet radiation, and radiation than PET. Therefore, PEN has broad application prospects in fibers, films, packaging materials, and engineering plastics. However, the high technical barriers to PEN monomer production have limited the development of PEN resin.

[0003] Therefore, in the field of high-temperature resistant polyester materials, providing a novel diacid monomer for the preparation of heat-resistant polyester resin has significant industrial application value. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a dimethyl-bridged decahydronaphthalene difunctional compound, its preparation method, and its applications. This compound is a dimethyl-bridged decahydronaphthalene dicarboxylate. Due to its high molecular weight, rigid diester structure, saturated alicyclic structure, and multiple isomers, it can be used in polyester materials to increase the glass transition temperature, enabling the preparation of highly transparent, bisphenol A-free, and heat-resistant polyester resins.

[0005] The objective of this invention can be achieved through the following technical solutions: In a first aspect, a difunctional compound containing a dimethyl-bridged decahydronaphthalene skeleton is provided, said compound being a dimethyl-bridged decahydronaphthalene dicarboxylate, the structure of which comprises a mixture of various isomers, as shown in the following structural formula:

[0006] R is selected from CH3, C2H5, C3H7 or C4H9.

[0007] In a second aspect, a method for preparing the difunctional compound containing the dimethyl-bridged decahydronaphthalene skeleton described in the first aspect is provided, comprising the following steps: using dimethyl-bridged octahydronaphthalene carboxylate as a starting material, performing a hydrogen esterification reaction in the presence of a carbonylation catalyst composed of bidentate organophosphorus ligands complexed with palladium, a solvent, and a co-catalyst, followed by post-treatment and distillation separation to obtain the dimethyl-bridged decahydronaphthalene dicarboxylate.

[0008] Furthermore, in the carbonylation catalyst, the palladium metal is selected from palladium acetate, palladium chloride, palladium nitrate, palladium sulfate, di(benzylacetone)palladium, palladium acetylacetonate, and dibromo(1,5-cyclooctadiene)palladium; the bidentate organophosphorus ligand has the following structure:

[0009] In L1-L4 and L5-L8, X is selected from CH2, C(CH3)2, O or SO2, respectively.

[0010] Specifically, the bidentate organophosphine ligand is selected from one of the structures shown in L1, L2, L3, L4, L5, L6, L7, and L8, wherein X is selected from CH2, C(CH3)2, O, or SO2, respectively.

[0011] Further, the solvent is one or more selected from C1-4 alcohol, tetrahydrofuran, methyltetrahydrofuran, dioxane, cyclohexane, methylcyclohexane, toluene, xylene, DMF, and DMAC.

[0012] Specifically, C1-4 alcohol is one of methanol, ethanol, and propanol.

[0013] Furthermore, the co-catalyst is one of p-toluenesulfonic acid, methanesulfonic acid, sulfuric acid, trifluoromethanesulfonic acid, trifluoroacetic acid, and macroporous sulfonic acid resin.

[0014] Furthermore, the hydrogen esterification reaction is carried out in a high-pressure reactor at a temperature of 80-150°C, a pressure of 1-5 MPa, and a reaction time of 5-10 h.

[0015] Specifically, bidentate phosphine ligand and palladium metal are added to a high-pressure reactor containing dimethyl-bridged octahydronaphthyl ester, auxiliaries, and solvents, and then hydrogen esterification is carried out under CO atmosphere.

[0016] Thirdly, a polyester resin is provided, which is prepared by polycondensation reaction of the dimethyl-bridged decahydronaphthalene dicarboxylate and a diol as described in the first aspect.

[0017] Specifically, dimethyl-bridged decahydronaphthalene dicarboxylate is mixed with a diol and heated to 150-180°C under a nitrogen atmosphere for esterification reaction for 4-5 hours. Then, the temperature is raised to 220°C and polycondensed under vacuum for 3-4 hours to obtain a polyester resin.

[0018] Further, the diol is one or more of ethylene glycol (EG), 1,3-propanediol (PDO), 1,4-butanediol (BDO), 1,6-hexanediol (HDO), 1,4-cyclohexanediethanol (CHDM), tricyclodecanediethanol (TCDDM), and isosorbide (ISB).

[0019] Furthermore, the polyester resin has a glass transition temperature of 103-112°C, a light transmittance of 89-91% at a thickness of 2 mm, and an elongation at break of 5-43%.

[0020] One application is the use of the difunctional compound containing a dimethyl-bridged decahydronaphthalene skeleton as described in the first aspect in the preparation of highly transparent and weather-resistant polyester materials.

[0021] The beneficial effects of this invention are as follows: (1) This invention provides a diester compound containing a dimethyl-bridged decahydronaphthalene skeleton, namely dimethyl-bridged decahydronaphthalene dicarboxylate. This compound is a mixture of various isomers and has a highly rigid dinorbornene skeleton. Introducing it into the polyester backbone can restrict the movement of molecular chains, thereby increasing the glass transition temperature of the polyester resin. Example 7 shows that the polyester resin obtained by copolymerizing this compound with tricyclodecanediethanol and ethylene glycol can reach a glass transition temperature of 112°C, exhibiting excellent heat resistance, and is free of bisphenol A, making it safe and environmentally friendly.

[0022] (2) The compounds of this invention have a saturated alicyclic structure and no conjugated system in the molecule. They do not absorb visible light and near-ultraviolet light, so the resulting polyester resin has high light transmittance. The light transmittance of the polyester resin in Example 7 is 91%, and that in Example 8 is 89%. The material is colorless and transparent, and can be used in fields where high transparency is required.

[0023] (3) By selecting different types of diols for copolymerization, the flexibility of the polyester resin can be adjusted while maintaining a high glass transition temperature. The elongation at break in Example 7 was 5%, and the material was rigid. In Example 8, after introducing 1,4-butanediol copolymerization, the elongation at break increased to 43%, while the glass transition temperature only decreased by 9°C, indicating that the polyester resin of the present invention has good performance adjustability and broadens the application range of the material.

[0024] (4) This invention uses dimethyl-bridged octahydronaphthalenecarboxylate as a raw material, employs a bidentate organophosphorus ligand complexed with palladium as a catalyst, and uses methanesulfonic acid or p-toluenesulfonic acid as an auxiliary agent to prepare dimethyl-bridged decahydronaphthalenecarboxylate in one step via a hydrogen esterification reaction. By optimizing the palladium source, bidentate phosphorus ligand, and auxiliary agent, the product content can reach up to 63%, and the product content is significantly better when using methanesulfonic acid, p-toluenesulfonic acid, or other auxiliary agents than when using concentrated sulfuric acid. Attached Figure Description

[0025] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0026] Figure 1 The dimethyl-bridged decahydronaphthalene dicarboxylate prepared according to the present invention 1 H-NMR spectrum; Figure 2 The MS spectrum of methyl dimethylbridged decahydronaphthalenedicarboxylate of the present invention is shown below. Figure 3 The types of bidentate phosphine ligands in this invention are L1-L8. Detailed Implementation

[0027] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.

[0028] The dimethyl-bridged decahydronaphthalenedicarboxylate used in the following examples has the skeleton structure shown below. Its preparation method and application in polyester resins are detailed in the specific examples.

[0029] The dimethyl-bridged decahydronaphthalene dicarboxylate ester described in this invention includes, but is not limited to, its methyl ester form, namely dimethyl-bridged decahydronaphthalene dicarboxylate methyl ester. The methyl ester is used as an example in the embodiments.

[0030] The bidentate organophosphorus ligand structure used in this invention is as follows: Figure 3 As shown, specifically, the bidentate organophosphine ligand is selected from one of the structures shown in L1, L2, L3, L4, L5, L6, L7, and L8. In the structures of L1, L2, L3, and L4, the bridging group X connecting the two benzene rings is CH2, C(CH3)2, O, or SO2, respectively; in the structures of L5, L6, L7, and L8, the bridging group X connecting the two benzene rings is CH2, C(CH3)2, O, or SO2, respectively.

[0031] Example 1 22 g of dimethyl-bridged octahydronaphthalenecarboxylate, 23 mg of palladium acetate, ligand L1 (50 mg), methanesulfonic acid (40 mg), methanol (26 g), and tetrahydrofuran (100 mL) were added separately to a 250 mL high-pressure reactor. The reactor was then purged three times with nitrogen, followed by three purgings with carbon monoxide. After purging, CO was added to bring the pressure to 2.5 MPa. The stirring and heating program was started, and the temperature was raised to 100 °C. The reactor pressure was maintained at 3 MPa for 6 hours after the reaction started. After the reaction, the pressure was lowered to room temperature, then released to atmospheric pressure. Residual CO in the reactor was purged with nitrogen. A sample of the reaction solution was analyzed by gas chromatography to determine the content of the product, dimethyl-bridged decahydronaphthalenecarboxylate.

[0032] Example 2 22 g of dimethyl-bridged decahydronaphthalenedicarboxylate, 45 mg of palladium acetate, ligand L2 (107 mg), 50 mg of methanesulfonic acid, 26 g of methanol, and 100 mL of dioxane were added separately to a 250 mL high-pressure reactor. The reactor was then purged three times with nitrogen, followed by three purgings with carbon monoxide. After purging, CO was added to bring the pressure to 2.5 MPa. The stirring and heating program was started, and the temperature was raised to 100 °C. The reactor pressure was maintained at 3 MPa for 6 hours after the reaction started. After the reaction, the pressure was lowered to room temperature, then released to atmospheric pressure. Residual CO was purged with nitrogen. A sample of the reaction solution was analyzed by gas chromatography to determine the content of the product, dimethyl-bridged decahydronaphthalenedicarboxylate. The obtained product showed [specific properties / details]. 1 H-NMR spectrum as shown Figure 1 As shown, the MS spectrum is as follows Figure 2 As shown.

[0033] Example 3 Methyl dimethyl octahydronaphthyl acetate (22 g), palladium acetate (45 mg), ligand L2 (107 mg), concentrated sulfuric acid (50 mg), methanol (30 g), and dioxane (100 mL) were added separately to a 250 mL high-pressure reactor. The reactor was then purged three times with nitrogen, followed by three purgings with carbon monoxide. After purging, CO was added to bring the pressure to 2.5 MPa. The stirring and heating program was started, and the temperature was raised to 100 °C. The reactor pressure was maintained at 3 MPa after the reaction started for 6 hours. After the reaction was completed, the pressure was lowered to room temperature, then released to atmospheric pressure. Residual CO in the reactor was purged with nitrogen. A sample of the reaction solution was analyzed by gas chromatography to determine the product content.

[0034] Example 4 Methyl dimethyl-bridged octahydronaphthylcarboxylate (22 g), palladium acetylacetone (61 mg), ligand L3 (112 mg), p-toluenesulfonic acid (70 mg), methanol (30 g), and tetrahydrofuran (100 mL) were added separately to a 250 mL high-pressure reactor. The reactor was then purged three times with nitrogen, followed by three purgings with carbon monoxide. After purging, CO was added to bring the pressure to 2.5 MPa. The stirring and heating program was started, and the temperature was raised to 110 °C. The reactor pressure was maintained at 3 MPa after the reaction started for 6 hours. After the reaction was completed, the pressure was lowered to room temperature, then released to atmospheric pressure. Residual CO in the reactor was purged with nitrogen. A sample of the reaction solution was analyzed by gas chromatography to determine the product content.

[0035] Example 5 Methyl dimethyl octahydronaphthyl acetate (22 g), palladium acetate (45 mg), ligand L6 (100 mg), p-toluenesulfonic acid (70 mg), methanol (30 g), and dioxane (100 mL) were added separately to a 250 mL high-pressure reactor. The reactor was then purged three times with nitrogen, followed by three purgings with carbon monoxide. After purging, CO was added to bring the pressure to 2.5 MPa. The stirring and heating program was started, and the temperature was raised to 100 °C. The reactor pressure was maintained at 3 MPa after the reaction started for 6 hours. After the reaction was completed, the pressure was lowered to room temperature, then released to atmospheric pressure. Residual CO in the reactor was purged with nitrogen. A sample of the reaction solution was analyzed by gas chromatography to determine the product content.

[0036] Example 6 Methyl dimethyl octahydronaphthyl acetate (22 g), palladium acetate (45 mg), ligand L7 (100 mg), methanesulfonic acid (50 mg), methanol (30 g), and dioxane (100 mL) were added separately to a 250 mL high-pressure reactor. The reactor was then purged three times with nitrogen, followed by three purgings with carbon monoxide. After purging, CO was added to bring the pressure to 2.5 MPa. The stirring and heating program was started, and the temperature was raised to 100 °C. The reactor pressure was maintained at 3 MPa after the reaction started for 6 hours. After the reaction was completed, the pressure was lowered to room temperature, then released to atmospheric pressure. Residual CO in the reactor was purged with nitrogen. A sample of the reaction solution was analyzed by gas chromatography to determine the product content.

[0037] Example 7 Methyl dimethyl benzonaphthalene dicarboxylate, tricyclodecanediethanol (TCDDM), and ethylene glycol were added to an esterification reactor at a molar ratio of 1:0.3:1.5. Then, anhydrous zinc acetate catalyst (approximately 0.05% molar amount of methyl dimethyl benzonaphthalene dicarboxylate) was added. After nitrogen purging, the temperature was raised to 165°C under a nitrogen atmosphere for esterification. After 4.5 hours of reaction, tetrabutyl titanate catalyst (approximately 0.1% molar amount of methyl dimethyl benzonaphthalene dicarboxylate) was added. The temperature was gradually raised to 220°C, and the vacuum degree was adjusted to below 100 Pa. Polycondensation was carried out for 3.5 hours to obtain the copolyester DTcEG.

[0038] Example 8 Methyl dimethyl benzonaphthalene dicarboxylate, tricyclodecanediethanol (TCDDM), ethylene glycol, and 1,4-butanediol were added to an esterification reactor in a molar ratio of 1:0.2:1.5:0.2. Then, anhydrous zinc acetate catalyst (approximately 0.05% molar amount of methyl dimethyl benzonaphthalene dicarboxylate) was added. After nitrogen purging, the temperature was raised to 155°C under a nitrogen atmosphere for esterification. After 4 hours of reaction, antimony trioxide titanate catalyst (approximately 0.08% molar amount of methyl dimethyl benzonaphthalene dicarboxylate) was added. The temperature was gradually raised to 220°C, and the vacuum degree was adjusted to below 100 Pa. Polycondensation was carried out for 3 hours to obtain the copolyester DTcEBG.

[0039] Effect verification I. Testing Methods 1. Product content determination Gas chromatography was used to quantitatively analyze the target product, methyl dimethylbridged decahydronaphthalenedicarboxylate, in the hydrogen esterification reaction solution, and the internal standard method was used for quantification.

[0040] 2. Determination of glass transition temperature (Tg) Differential scanning calorimetry (DSC) was used for testing. The heating rate was 10℃ / min, and the atmosphere was nitrogen. The inflection point of the second heating curve was taken as the glass transition temperature.

[0041] 3. Transmittance Measurement A transmittance meter was used to test a 2mm thick polyester sample according to the GB / T 2410-2008 standard, and the transmittance (%) was recorded.

[0042] 4. Determination of elongation at break Tensile tests were performed using an electronic universal testing machine, and the elongation at break (%) was recorded.

[0043] II. Test Results The products and polyester resins prepared in each embodiment of the present invention were tested according to the above test methods, and the results are as follows: Table 1. Test results of methyl dimethyl phthalate decahydronaphthalate content.

[0044] Example 2, using bidentate ligand L2, palladium acetate, and methanesulfonic acid as auxiliaries, achieved the highest product content, reaching 63%. Examples 1, 4, 5, and 6, using different ligands, palladium sources, or auxiliaries, showed product contents ranging from 41% to 56%, all lower than Example 2. Example 3, using concentrated sulfuric acid instead of methanesulfonic acid, reduced the product content to 32%. This indicates that using methanesulfonic acid, p-toluenesulfonic acid, etc., as auxiliaries significantly resulted in higher product contents than using concentrated sulfuric acid.

[0045] By optimizing the palladium source, bidentate phosphine ligand, and auxiliaries, the hydrogen esterification reaction of the present invention can achieve a high product content, up to 63%.

[0046] Table 2. Performance test results of polyester resin

[0047] Example 7 used dimethyl-bridged decahydronaphthalene dicarboxylate copolymerized with tricyclodecanediethanol and ethylene glycol, resulting in a polyester resin DTcEG with a glass transition temperature (Tg) of 112°C. Example 8, after introducing 1,4-butanediol, showed a Tg of 103°C, both exhibiting high heat resistance. The compounds of this invention possess a highly rigid dinorbornene backbone. Introducing this backbone into the polyester backbone, the rigid alicyclic structure restricts molecular chain movement, thereby significantly increasing the glass transition temperature of the polyester resin.

[0048] The polyester resin in Example 7 had a light transmittance of 91%, and in Example 8 it was 89%, both reaching a high level of transparency. The compounds of this invention have a saturated alicyclic structure, with no conjugated systems in the molecule, and do not absorb visible light or near-ultraviolet light. Therefore, the resulting polyester resin has high light transmittance, and the material is colorless and transparent, making it suitable for fields with stringent transparency requirements, such as optical devices and high-end packaging.

[0049] Example 7 showed an elongation at break of 5%, indicating a rigid material. In Example 8, the introduction of 1,4-butanediol copolymerization increased the elongation at break to 43%, while the temperature gradient (Tg) decreased by only 9°C. This demonstrates that by adjusting the type and proportion of the copolymerized diol, the flexibility of the material can be controlled while maintaining high heat resistance, thus meeting the needs of different applications.

[0050] This invention employs a bidentate organophosphorus ligand complexed with palladium as a carbonylation catalyst, using methanesulfonic acid or p-toluenesulfonic acid as an auxiliary agent. It exhibits high selectivity for the hydrogen esterification reaction of dimethyl-bridged octahydronaphthyl ester, and by optimizing the ligand (e.g., L2) and auxiliary agent (e.g., methanesulfonic acid), the product content can reach up to 63%. Polyester resins prepared using the compounds of this invention possess high glass transition temperature and high transmittance. Furthermore, by introducing comonomers such as 1,4-butanediol, the flexibility of the material can be adjusted while maintaining a high glass transition temperature (Tg). The dinorbornene skeleton of the compounds of this invention provides high rigidity, which is the structural basis for achieving high Tg; the saturated alicyclic structure, free of conjugated systems, is the structural basis for achieving high transparency.

[0051] In summary, this invention successfully provides a difunctional compound with a dimethylbridged decahydronaphthalene skeleton and its preparation method, and the application of this compound in polyester materials has achieved significant beneficial effects.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A difunctional compound containing a dimethyl-bridged decahydronaphthalene skeleton, characterized in that, The compound is dimethylbridged decahydronaphthalene dicarboxylate, and its structure comprises a mixture of various isomers, as shown in the following structural formula: R is selected from CH3, C2H5, C3H7 or C4H9.

2. A method for preparing a difunctional compound containing a dimethyl-bridged decahydronaphthalene skeleton as described in claim 1, characterized in that, Includes the following steps: Using dimethyl-bridged octahydronaphthalenecarboxylate as the starting material, a hydrogen esterification reaction was carried out in the presence of a carbonylation catalyst composed of bidentate organophosphorus ligands complexed with palladium, a solvent, and a co-catalyst. After post-treatment and distillation separation, the dimethyl-bridged decahydronaphthalenecarboxylate was obtained.

3. The method for preparing the difunctional compound containing a dimethyl-bridged decahydronaphthalene skeleton according to claim 2, characterized in that, In the carbonylation catalyst, the palladium metal is selected from palladium acetate, palladium chloride, palladium nitrate, palladium sulfate, bis(benzylidene acetone)palladium, palladium acetylacetonate, and dibromo(1,5-cyclooctadiene)palladium; the bidentate organophosphorus ligand has the following structure: In L1-L4 and L5-L8, X is selected from CH2, C(CH3)2, O or SO2, respectively.

4. The method for preparing the difunctional compound containing a dimethyl-bridged decahydronaphthalene skeleton according to claim 2, characterized in that, The solvent is one or more of C1-4 alcohol, tetrahydrofuran, methyltetrahydrofuran, dioxane, cyclohexane, methylcyclohexane, toluene, xylene, DMF, and DMAC.

5. The method for preparing the difunctional compound containing a dimethyl-bridged decahydronaphthalene skeleton according to claim 2, characterized in that, The co-catalyst is one of p-toluenesulfonic acid, methanesulfonic acid, sulfuric acid, trifluoromethanesulfonic acid, trifluoroacetic acid, or macroporous sulfonic acid resin.

6. The method for preparing the difunctional compound containing a dimethyl-bridged decahydronaphthalene skeleton according to claim 2, characterized in that, The hydrogen esterification reaction is carried out in a high-pressure reactor at a temperature of 80-150°C, a pressure of 1-5 MPa, and a reaction time of 5-10 h.

7. A polyester resin, characterized in that, The polyester resin is prepared by polycondensation reaction of the dimethyl-bridged decahydronaphthalene dicarboxylate as described in claim 1 and a diol.

8. The polyester resin according to claim 7, characterized in that, The diol is one or more of ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanediethanol, tricyclodecanediethanol, and isosorbide.

9. The polyester resin according to claim 7, characterized in that, The polyester resin has a glass transition temperature of 103-112℃, a light transmittance of 89-91% at a thickness of 2mm, and an elongation at break of 5-43%.

10. The application of the difunctional compound containing a dimethylbridged decahydronaphthalene skeleton as described in claim 1 in the preparation of highly transparent and weather-resistant polyester materials.

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