Sorbitol ester and production process thereof

Abstract

The invention discloses sorbitol ester and a production process thereof, and belongs to the technical field of chemical industry. The sorbitol ester comprises hardened oil, stearic acid, sorbitol and a catalyst; during production and preparation, the weighed hardened oil and stearic acid are added into a reaction kettle and heated to 150-180 DEG C, after the materials are completely melted, correctly weighed sorbitol is slowly added, finally, a catalyst is added, the temperature continues to rise to 190-240 DEG C, and the temperature is kept for 30-60 min; after the reaction is finished, vacuumizing, cooling the product to 100-120 DEG C through a condenser, and introducing the product into a slicing machine to obtain a flaky product; the flaky solid sorbitol ester is generated by adopting a one-step reaction method, aiming at the use in the plastic industry, the hardened oil is newly added into the raw materials, the later product has excellent performance in the application of the calcium-zinc stabilizer, and when the product is used in the calcium-zinc stabilizer, the plasticizing promoting effect can be achieved, the melt viscosity is reduced, and the product is not easy to separate out in the later period.

Description

Technical Field

[0001] The invention relates to a sorbitol ester and a production process thereof, belonging to the technical field of chemical industry. Background Art

[0002] Sorbitol esters are a class of compounds produced by esterification of sorbitol (sorbitol) and fatty acids. Sorbitol esters are sometimes also called sorbitol esters. Sorbitol esters are important chemical raw materials with excellent emulsification and dispersing properties. They can be mixed with various types of surfactants. They have been widely used in the fields of food, medicine, and cosmetics, and also play an important role in textiles, leather, and plastics. In the textile industry, they are used as antistatic agents for acrylic fibers and components of softening oiling agents. In the coating and plastic industries, they are used as emulsifiers, stabilizers, etc.

[0003] There are many methods for producing sorbitol esters, including a one-step method, a method of esterification followed by etherification, and a method of etherification followed by esterification. The methods are roughly as follows: a one-step reaction using an alkali as a catalyst, mainly NaOH as a catalyst, a direct reaction using an alkali as a catalyst, with the improvement that an inert gas protection is added to the reaction until the reaction is completed, to obtain the product; a one-step reaction using an acid as a catalyst, mainly H3PO4 as a catalyst, using an acid as a catalyst, sorbitol and fatty acids directly react to obtain the product; a one-step reaction using a salt as a catalyst, mainly carbonates and acetates, using calcium acetate or barium acetate as a catalyst, sorbitol and fatty acids directly react to obtain the product; a two-step reaction using an alkali and an acid (or an acid and an alkali) as a catalyst, first dehydrating sorbitol under sulfuric acid conditions, and then obtaining the product through a two-step reaction under alkaline conditions.

[0004] The sorbitol ester products produced by the traditional one-step process have dark color, many by-products and unstable quality. In addition, the conventionally produced sorbitol ester products are mostly used in the food industry, etc., and their application is limited. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The technical problem to be solved by the present invention is to solve the problem that existing sorbitol ester products are mostly used in the food industry and the like, and their application is limited.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention provides a sorbitol ester, which comprises hardened oil, stearic acid, sorbitol and a catalyst. In parts by weight, the content of each component is:

[0009]

[0010]

[0011] The content of each component can also be, for example:

[0012]

[0013] The content of each component can also be, for example:

[0014]

[0015] The sorbitol ester is used in the calcium zinc stabilizer to promote plasticization, reduce melt viscosity, and is not easy to precipitate or does not precipitate in the later stage.

[0016] Furthermore, the hardened oil contains not less than 85% by mass of stearic acid and not more than 15% by mass of palmitic acid.

[0017] Furthermore, the hardened oil is fully hydrogenated microalgae oil, the trans fatty acid content of which is less than 0.3%, and the iodine value is less than 3gI2 / 100g; the hardened oil contains stearic acid of not less than 90% by mass, palmitic acid of not more than 10% by mass, and arachidic acid of not more than 5% by mass.

[0018] Furthermore, the stearic acid contains 10-20% isostearic acid, and the isostearic acid is an isomerization modification product, the number of branched carbon atoms is not less than 2, and the branch positions are the 8th to 12th carbon atoms.

[0019] Furthermore, the sorbitol is compounded with pentaerythritol, and the mass ratio of sorbitol to pentaerythritol is 4:1-6:1, the hydroxyl substitution degree of the pentaerythritol is 2-3, and the esterification reaction with sorbitol occurs preferentially at the primary hydroxyl site, and through nuclear magnetic resonance hydrogen spectrum detection, the esterification proportion of the primary hydroxyl group is not less than 80%.

[0020] Furthermore, the catalyst is a complex of calcium stearate and zinc stearate, wherein the molar ratio of calcium to zinc is 1:2 to 1:3.

[0021] Furthermore, the catalyst particle size is not more than 1 μm, and the specific surface area is not less than 20 m 2 / g; the catalytic mechanism is that calcium zinc ions form a complex with the free hydroxyl groups of sorbitol esters, inhibiting thermal oxidative degradation during processing.

[0022] Furthermore, the acid value of the sorbitol ester is no more than 3 mg KOH / g, the hydroxyl value is no more than 50 mg KOH / g, and the melt viscosity measured at a temperature of 160° C. is no more than 200 mPa·s.

[0023] Furthermore, the compatibility of the sorbitol ester with the PVC resin meets the following conditions: the mobility is ≤0.5% after being placed in a high temperature environment of 70°C for 168 hours; and the dynamic thermal stability at a temperature of 180°C is ≥60min.

[0024] The present invention also provides a production process of the sorbitol ester described above, which comprises the following steps: adding hardened oil and stearic acid weighed correctly according to the formula into a reaction kettle, heating to 150°C to 180°C, slowly adding the correctly weighed sorbitol after the materials are completely melted, and finally adding a catalyst, continuing to heat to 190°C to 240°C, and maintaining for 30min to 60min; after the reaction is completed, vacuuming and cooling the product to 100°C to 120°C through a condenser, and then introducing it into a slicer to obtain a sheet product.

[0025] (III) Beneficial effects

[0026] The above technical solution of the present invention has the following advantages:

[0027] The sorbitol ester of the present application starts with aspects such as composition adjustment, synergistic effect, thermal stability, compatibility, molecular structure and preparation process, so that the prepared sorbitol ester product is subsequently used in calcium zinc stabilizer (for the plastics industry), plays a role in promoting plasticization, reduces melt viscosity, and is not easy to separate out in the later stage. The sorbitol ester prepared by the present application is a flaky solid. When it is used in the plastics industry, the flaky solid form is easy to be evenly dispersed in the material system, can optimize plasticization efficiency, enhance material flexibility and ductility, and the flaky solid is also easy to quantitatively feed, reduce the loss in the production process, and reduce processing costs; In addition, the flaky form is more difficult to absorb moisture and agglomerate than powder, and the physical stability is high, which is convenient for long-term storage and transportation. Again, one-step reaction generation eliminates the intermediate treatment of multiple steps, significantly shortens the production cycle and reduces equipment investment, reduces energy consumption and waste of raw materials, thereby reducing comprehensive production costs, is suitable for industrialized continuous production, and has stable process. Finally, hardened oil is newly added to the raw material, and the product coming out in the later stage has excellent performance in the application of calcium zinc stabilizer.

[0028] The present invention also has the following advantages:

[0029] (1) Component synergistic optimization

[0030] Branching of isostearic acid: reduces molecular regularity and inhibits crystallization;

[0031] Pentaerythritol compounding: improve the thermal stability of the esterification product (pentaerythritol has better temperature resistance than sorbitol);

[0032] Calcium zinc composite catalyst: While catalyzing the esterification reaction, it is directly embedded into the system as a stabilizer component.

[0033] (2) Performance-oriented regulation:

[0034] Melt viscosity control: reducing polarity by compounding branched fatty acids and polyols;

[0035] Anti-migration design: High saturation hardened oil + branched chain structure improves compatibility with PVC;

[0036] Dynamic thermal stability: The calcium-zinc complexation mechanism inhibits the release of HCl during processing.

[0037] The invention can improve the quality of sorbitol ester and the application performance thereof.

[0038] In addition to the technical problems solved by the present invention, the technical features of the technical solutions constituted by the present invention, and the advantages brought about by the technical features of these technical solutions described above, other technical features of the present invention and the advantages brought about by these technical features will be further explained in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 It is a comparison diagram of the rheometer curve when the present invention is used in a calcium zinc stabilizer and the rheometer curve of a conventional calcium zinc stabilizer. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Embodiment 1: A sorbitol ester, characterized in that it comprises hardened oil, stearic acid, sorbitol and a catalyst;

[0043] The content of each component is as follows:

[0044]

[0045] The sorbitol ester is used in the calcium zinc stabilizer to promote plasticization, reduce melt viscosity, and is not easy to precipitate in the later stage. When used specifically, the optimal amount is 2 parts of calcium zinc stabilizer plus 0.2 parts of the sorbitol ester of the present application, and the specific effect is as follows: Figure 1 As shown (the rheological sample formula can be conventionally set according to the technical means in this field, such as: PVC (SG-5): 57g, CaCO 3 :8g, CPE:2.5g, Ti0 2 : 1.0g; sample to be tested: 1.5g; experimental equipment: Harbin Harp torque rheometer; temperature: 180℃; speed: 60r / min). Calcium zinc stabilizer is mainly used in materials such as PVC to prevent thermal degradation. The sorbitol ester of this embodiment has a good synergistic effect with calcium zinc, which can increase the flexibility and processability of the material and has good compatibility and stability in the material.

[0046] Example 2: This example is based on Example 1 and further optimizes and refines the hardened oil.

[0047] The hardened oil contains stearic acid (C18:0) of not less than 85% by mass and palmitic acid (C16:0) of not more than 15% by mass. The fatty acid composition of the hardened oil directly affects the performance of sorbitol esters (such as melt viscosity and anti-precipitation properties) and needs to be regulated by a hydrogenation process. Stearic acid ≥ 85%: ensures uniform chain length of the esterification product and enhances the synergistic plasticizing effect with the calcium zinc stabilizer; Palmitic acid ≤ 15%: inhibits the "blooming" phenomenon caused by the migration of short-chain fatty acids during processing. Whether the fatty acid distribution in the hardened oil meets the requirements can be determined by gas chromatography (GC) or nuclear magnetic resonance (NMR).

[0048] In this embodiment, in order to achieve fatty acid ratio control, on the one hand, an oil source with a high stearic acid content (such as fully hydrogenated microalgae oil) can be used in raw material selection; on the other hand, in the hydrogenation process, the hydrogen pressure, catalyst type (such as nickel-based catalyst) and reaction temperature can be adjusted to selectively saturate C18:1 (oleic acid) to generate C18:0; at the same time, a heterogeneous catalyst (such as platinum / carbon) can be used to avoid the risk of nickel residue.

[0049] Therefore, in this embodiment, the hardened oil is fully hydrogenated microalgae oil, and its trans fatty acid content is less than 0.3%, which meets environmental protection requirements, and the iodine value is less than 3gI2 / 100g, ensuring high saturation, reducing unsaturated bonds, improving thermal stability, and preventing oxidation. More preferably, the hardened oil contains stearic acid with a mass percentage of not less than 90% (by increasing the stearic acid ratio (≥90%), the palmitic acid content is indirectly compressed, the thermal stability is improved, and the melt viscosity is reduced), palmitic acid with a mass percentage of not more than 10% and arachidic acid (C20:0) with a mass percentage of not more than 5%, and arachidic acid is added as an auxiliary component to further optimize the performance, inhibit crystallization through arachidic acid, and improve compatibility with PVC (but too high arachidic acid (C20:0) content will lead to a decrease in compatibility with PVC). It is also possible to analyze the fatty acid distribution of the hardened oil according to ISO 12966-4:2025 "Gas Chromatographic Analysis of Fatty Acid Methyl Esters of Animal and Vegetable Oils and Fats", and by gas chromatography (GC) or mass spectrometry (MS).

[0050] The hardened oil uses fully hydrogenated microalgae oil, and its fatty acid composition is adjusted to optimize the interaction with calcium and zinc. Increasing the proportion of stearic acid helps complex with metal ions, thereby enhancing the stabilization effect. At the same time, the hardened oil has a lower iodine value, ensuring a higher degree of saturation, reducing unsaturated bonds, improving thermal stability and preventing oxidation.

[0051] Embodiment 3: This embodiment is based on embodiment 1, and further optimizes and refines stearic acid.

[0052] The stearic acid contains 10-20% isostearic acid (branched structure), and the remaining 80-90% is straight-chain stearic acid (normal stearic acid, which can be of pharmaceutical grade purity (≥99%), and free fatty acid residue <0.3%), which reduces molecular regularity and inhibits crystallization. The isostearic acid is an isomerization-modified product, and its branched carbon number is not less than 2, and the branch position is the 8th to 12th carbon atom. Stearic acid is introduced into the side chain or modified, and the present embodiment introduces isostearic acid, which can reduce crystallinity and reduce precipitation. The branched structure can improve compatibility with PVC and avoid migration.

[0053] In this embodiment, the branched structure (isostearic acid) reduces the intermolecular force, causing the melt viscosity to drop by 15% to 25%, which is convenient for extrusion molding; the straight chain structure provides skeleton support to avoid excessive branching leading to softening of the material (such as Shore hardness ≥ 80D). Thus, the processing performance of the product can be optimized. In addition, the linear stearic acid inhibits the de-HCl reaction through the polar interaction between the carboxyl group and the PVC chain; the proportion of isostearic acid ≤ 20% can avoid the low thermal decomposition temperature of the branched chain (about 200°C) causing scorch, thereby providing a guarantee for thermal stability.

[0054] Testing methods and standards support

[0055] Verification of ingredient ratio: Gas chromatography-mass spectrometry (GC-MS) (ISO 12966-2025) quantitative analysis of the linear / branched ratio; Nuclear magnetic resonance (NMR) confirmation of the branched structure (such as the methyl branch peak of isostearic acid).

[0056] Performance correlation: Melt viscosity: ISO 2555-2025 (rotational viscometer, 160°C); Thermal stability: TGA test (ASTM E1131-2025, nitrogen atmosphere, heating rate 10°C / min).

[0057] Example 4: This example is based on Example 1, and further optimizes and refines sorbitol.

[0058] The sorbitol is compounded with pentaerythritol (compounded polyol synergistic effect), and the mass ratio of sorbitol to pentaerythritol is 4:1 to 6:1, and the hydroxyl substitution degree of the pentaerythritol is 2 to 3 (meaning that in each pentaerythritol molecule, an average of 2 to 3 hydroxyl groups (-OH) participate in the esterification reaction to generate an ester group (-OOCR)). If the substitution degree is too low (such as ≤1), the product has high polarity and is easy to absorb water, which affects thermal stability; if the substitution degree is too high (such as ≥4), the steric hindrance increases, reducing the compatibility with PVC. The esterification reaction with sorbitol occurs preferentially at the primary hydroxyl site (sorbitol preferentially combines with the primary hydroxyl of pentaerythritol rather than the secondary hydroxyl in the esterification reaction), the primary hydroxyl has small steric hindrance, the reaction rate is fast, and the product structure is more regular; ensure the consistency of the spatial arrangement of sorbitol esters, improve the anti-migration and plasticization efficiency. And through nuclear magnetic resonance hydrogen spectrum detection, the esterification proportion of primary hydroxyl is not less than 80%.

[0059] As a polyol, the degree of esterification of sorbitol will affect the polarity of the final product. Increasing the amount of sorbitol may increase the polarity of the ester, thereby enhancing the complexation with calcium and zinc, but too much sorbitol may lead to increased viscosity, which requires a balance. Therefore, this embodiment adjusts the compounding of sorbitol with other polyols, specifically by adding pentaerythritol, which can improve thermal stability.

[0060] Example 5: This example is a further optimization and refinement of the catalyst based on Examples 2-4.

[0061] The catalyst is a complex of calcium stearate and zinc stearate, wherein the molar ratio of calcium to zinc is 1:2 to 1:3 (refer to ISO 11885:2025 "Water Quality-Determination of Metal Elements-ICP Method", the Ca and Zn contents in the complex are determined by atomic absorption spectroscopy (AAS) or inductively coupled plasma (ICP), which is the mixing ratio of the two metal salts in the complex, directly affecting thermal stability and synergistic effect. The composite catalyst of calcium stearate and zinc stearate can be used as a catalyst and stabilizer at the same time, reducing late precipitation, because the catalyst residue can become part of the stabilizer.

[0062] The catalyst particle size does not exceed 1 μm, and the nano-scale particles are evenly dispersed, which improves the contact efficiency with sorbitol ester and the catalytic activity by 30%; the specific surface area is not less than 20m 2 / g, high specific surface area provides more active sites, enhancing the complexing ability of calcium / zinc ions and hydroxyl groups. Synergistic effect: nanoparticle size + high specific surface area → the catalyst is fully in contact with the sorbitol ester molecules to form a dense complexing network; the system that meets this condition can extend the thermal stability time of PVC (TGA method) from 50min to 120min.

[0063] The catalytic mechanism is that calcium zinc ions form a complex with the free hydroxyl groups of sorbitol esters, inhibiting the thermal oxidative degradation during processing. 2+ / Zn 2+ The free hydroxyl group (-OH) of sorbitol ester is combined with the free hydroxyl group (-OH) through a coordination bond to reduce the possibility of thermal oxidation of hydroxyl group to generate free radicals; in addition, zinc ion (Zn 2+ ) captures HCl (PVC degradation byproduct) and inhibits autocatalytic degradation; calcium ions (Ca 2+ ) neutralizes the acidic environment and protects the structural integrity of sorbitan esters.

[0064] In this embodiment, the synergistic effect of the presence of stearic acid and calcium zinc catalyst is as follows:

[0065] The synergistic effect of stearic acid (straight chain + branched chain) and calcium zinc composite catalyst is reflected in the improvement of thermal stability, optimization of processing fluidity and enhancement of environmental protection. The specific mechanism is as follows:

[0066] Thermal stability: (1) Mechanism of action: Stearic acid releases H+ as an acid source, promoting the 2 + / Zn2+) complexes with sorbitol ester hydroxyl groups to inhibit free radical chain reactions; straight-chain stearic acid strengthens intermolecular hydrogen bonds and reduces thermal decomposition. (2) Technical index correlation: TGA thermal stability time is improved (≥120min).

[0067] Processing fluidity: (1) Mechanism of action: Branched stearic acid (isostearic acid) reduces melt viscosity; calcium zinc nanoparticles (≤1μm) are evenly dispersed to reduce melt friction resistance. (2) Correlation of technical indicators: Torque rheometer fluctuation value is reduced (≤5%).

[0068] Environmental protection: (1) Mechanism of action: Calcium zinc replaces traditional lead / cadmium stabilizers; stearic acid and sorbitol ester form a stable complex to reduce small molecule migration (migration rate ≤ 0.5%). (2) Correlation of technical indicators: Complies with REACH 2025 and FDA food contact material standards.

[0069] Example 6: This example is a further optimization and refinement of sorbitol ester based on Examples 1-5.

[0070] The acid value of the sorbitol ester does not exceed 3 mg KOH / g (inhibiting the autocatalytic effect of H Cl in the degradation process of PVC and improving the chemical stability of sorbitol ester, testing method: GB / T 5530-2025 "Determination of acid value and acidity of animal and vegetable oils"); the hydroxyl value does not exceed 50 mg KOH / g (reducing the hydrophilicity of sorbitol ester and improving the compatibility with PVC resin, testing method: ASTM D4273-2025 "Determination of hydroxyl value of polyols"); and the melt viscosity measured at a temperature of 160°C does not exceed 200 mPa·s (ensuring rapid dispersion in the extrusion / injection molding process and avoiding gelation caused by high molecular weight components, testing method: ISO 2555-2025 "Plastics-Determination of melt viscosity-Rotational viscometer method").

[0071] Synergistic effect and commercial value: The low acid value (≤3mg KOH / g) of the sorbitol ester of this embodiment reduces the attack of the acidic environment on the PVC chain; the low hydroxyl value (≤50mg KOH / g) inhibits the reaction of hydroxyl and H Cl to generate water (avoiding accelerated degradation). Improve thermal stability. In addition, low melt viscosity (≤200mPa·s) reduces screw torque and saves 15% to 20% of energy consumption; improved fluidity allows the stabilizer to be evenly dispersed in PVC, reducing "fisheye" defects. Optimize processing efficiency. Finally, synergistic control of acid value / hydroxyl value can improve the weather resistance of PVC products (such as door and window profiles) by more than 30%; low viscosity ensures that the processing temperature is ≤160°C to avoid high temperature causing the stabilizer to decompose itself. Extend the life of the end product.

[0072] In this embodiment, the compatibility of the sorbitol ester and the PVC resin meets the following conditions: the mobility is ≤0.5% after being placed in a high temperature environment of 70°C for 168 hours (to prevent the precipitation of additives → to avoid surface stickiness, atomization or contamination); the dynamic thermal stability at a temperature of 180°C is ≥60min (tested by a torque rheometer), inhibiting thermal oxidation degradation → maintaining melt strength, avoiding scorch and yellowing, and ensuring continuous production stability. The calcium stearate / zinc composite catalyst forms a thermally stable complex with the sorbitol ester, which prolongs the oxidation induction period of the PVC melt.

[0073] Comparison of experimental data: Mobility (70°C×168h): conventional sorbitol ester 0.8%~1.2%, the present application 0.3%~0.5% (meeting the standard); Dynamic thermal stability (180°C): conventional sorbitol ester 35~45min, the present application 60~75min (increased by 36%~107%).

[0074] Example 7: This example provides a production process for the sorbitol ester of the above example, which comprises the following steps: adding hardened oil and stearic acid weighed correctly according to the formula into a reaction kettle, heating to 150°C to 180°C, and slowly adding the correctly weighed sorbitol after the materials are completely melted, and finally adding a catalyst, continuing to heat to 190°C to 240°C, and maintaining for 30min to 60min; after the reaction is completed, vacuuming and cooling the product to 100°C to 120°C through a condenser, and then introducing it into a slicer to obtain a sheet product.

[0075] The sorbitol ester of the present application starts with aspects such as composition adjustment, synergistic effect, thermal stability, compatibility, molecular structure and preparation process, so that the prepared sorbitol ester product is subsequently used in calcium zinc stabilizer (for the plastics industry), plays a role in promoting plasticization, reduces melt viscosity, and is not easy to separate out in the later stage. The sorbitol ester prepared by the present application is a flaky solid. When it is used in the plastics industry, the flaky solid form is easy to be evenly dispersed in the material system, can optimize plasticization efficiency, enhance material flexibility and ductility, and the flaky solid is also easy to quantitatively feed, reduce the loss in the production process, and reduce processing costs; In addition, the flaky form is more difficult to absorb moisture and agglomerate than powder, and the physical stability is high, which is convenient for long-term storage and transportation. Again, one-step reaction generation eliminates the intermediate treatment of multiple steps, significantly shortens the production cycle and reduces equipment investment, reduces energy consumption and waste of raw materials, thereby reducing comprehensive production costs, is suitable for industrialized continuous production, and has stable process. Finally, hardened oil is newly added to the raw material, and the product coming out in the later stage has excellent performance in the application of calcium zinc stabilizer.

[0076] The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A sorbitol ester, characterized in that: Contains hardened oil, stearic acid, sorbitol and catalyst; The content of each component is as follows by weight: The sorbitol ester is used in the calcium zinc stabilizer to promote plasticization, reduce melt viscosity, and is not easy to precipitate in the later stage.

2. The sorbitol ester according to claim 1, characterized in that: The hardened oil contains not less than 85% by mass of stearic acid and not more than 15% by mass of palmitic acid.

3. The sorbitol ester according to claim 2, characterized in that: The hardened oil is fully hydrogenated microalgae oil, the trans fatty acid content of which is less than 0.3%, and the iodine value is less than 3gI2 / 100g; the hardened oil contains stearic acid accounting for not less than 90% by weight, palmitic acid accounting for not more than 10% by weight, and arachidic acid accounting for not more than 5% by weight.

4. The sorbitol ester according to claim 1, characterized in that: The stearic acid contains 10-20% isostearic acid, and the isostearic acid is an isomerization modification product, the number of its branched carbon atoms is not less than 2, and the branching positions are the 8th to 12th carbon atoms.

5. The sorbitol ester according to claim 1, characterized in that: The sorbitol is compounded with pentaerythritol, and the mass ratio of sorbitol to pentaerythritol is 4:1-6:

1. The degree of hydroxyl substitution of the pentaerythritol is 2-3, and the esterification reaction with sorbitol occurs preferentially at the primary hydroxyl site. According to nuclear magnetic resonance hydrogen spectrum detection, the esterification proportion of the primary hydroxyl group is not less than 80%.

6. The sorbitol ester according to claim 1, characterized in that: The catalyst is a complex of calcium stearate and zinc stearate, wherein the molar ratio of calcium to zinc is 1:2 to 1:

3.

7. The sorbitol ester according to claim 6, characterized in that: The catalyst particle size is not more than 1 μm and the specific surface area is not less than 20 m 2 / g; the catalytic mechanism is that calcium zinc ions form a complex with the free hydroxyl groups of sorbitol esters, inhibiting thermal oxidative degradation during processing.

8. The sorbitol ester according to claim 1, characterized in that: The acid value of the sorbitol ester is no more than 3 mgKOH / g, the hydroxyl value is no more than 50 mgKOH / g, and the melt viscosity measured at a temperature of 160° C. is no more than 200 mPa·s.

9. The sorbitol ester according to claim 8, characterized in that The compatibility of the sorbitol ester with the PVC resin meets the following conditions: the migration rate is ≤0.5% after being placed in a high temperature environment of 70°C for 168 hours; and the dynamic thermal stability is ≥60min at a temperature of 180°C.

10. The process for producing sorbitol ester according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: adding hardened oil and stearic acid weighed correctly according to the formula into a reaction kettle, heating to 150-180°C, slowly adding sorbitol weighed correctly after the materials are completely melted, and finally adding a catalyst, continuing to heat to 190-240°C, and maintaining for 30-60 minutes; after the reaction is completed, vacuuming and cooling the product to 100-120°C through a condenser, and then introducing the product into a slicer to obtain a sheet product.

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