A low migration plasticizer and its application in preparing high molecular polymer materials

Abstract

The invention discloses a low-migration plasticizer and its application in the preparation of polymer materials, and relates to the technical field of polymer material preparation. The raw materials of the plasticizer include monomers; the monomers are composed of ethylene, vinyl acetate and a third cross-linking monomer, vinyl acetate accounts for 40-80% of the total monomer mass, and the amount of the third cross-linking monomer is 2-10% of the total monomer mass; the third cross-linking monomer is at least one of ethoxyethyl acrylate, propoxylated neopentyl glycol diacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, and dipentaerythritol hexaacrylate. The plasticizer of the present invention has the performance of low migration and good compatibility with polar polymers. It is applied to the plasticization process of polymer materials such as PVC, which can improve the flexibility of polymer materials while maintaining good mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of high molecular polymer material preparation, in particular to a low migration plasticizer and application thereof. Background Art

[0002] Plasticizers are widely used polymer material additives in industrial production, especially in polyvinyl chloride plastic products. The main function of plasticizers is to weaken the secondary bonds between resin molecules, increase the mobility of resin molecular bonds, reduce the crystallinity of resin molecules, increase the plasticity of plastics, improve the strength of plastics, enhance their flexibility, and make them easier to process. At present, the PVC plasticizers used in the domestic market are mainly low-molecular plasticizers of phthalates. These small molecule plasticizers will migrate to the surface of plastic products after long-term use, resulting in reduced performance of PVC products. Phthalate plasticizers can also cause harm to the environment and human health. Western developed countries have expressly prohibited the addition of phthalate additives to plastics.

[0003] At present, many domestic PVC product manufacturers have begun to use non-phthalate plasticizers, such as polyester plasticizers, mainly propylene glycol oxalate polyester, propylene glycol sebacic acid polyester, glutaric acid polyester, etc. This type of polyester polymer plasticizer can be used to replace small molecule plasticizers, improving the problem of small molecule plasticizer precipitation, but the compatibility of polyester plasticizers is poor. Some PVC product manufacturers also use trimellitic acid ester plasticizers, which have low volatility, low migration, and are resistant to extraction, but have low strength. Summary of the invention

[0004] In view of the above shortcomings of the prior art, the present invention provides a low migration plasticizer, the weight average molecular weight (Mw) of the plasticizer is between 300000-500000; due to the copolymerization of highly polar vinyl acetate monomer, it has good compatibility with PVC, large molecular weight, and good migration resistance; adding a special third cross-linking monomer significantly improves the strength of PVC products. Specifically achieved through the following technologies.

[0005] A low migration plasticizer, the raw materials of which include monomers, initiators and terminators; the monomers include ethylene and vinyl acetate, and the mass ratio of vinyl acetate to ethylene is (40-80):(20-60).

[0006] Furthermore, the monomer is composed of ethylene, vinyl acetate and a third cross-linking monomer, and the mass ratio of vinyl acetate, ethylene and the third cross-linking monomer is (40-80):(20-60):(0-10); the third cross-linking monomer is at least one of ethoxyethyl acrylate, propoxylated neopentyl glycol diacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate and dipentaerythritol hexaacrylate.

[0007] It should be noted that in some implementation cases of the present invention, in addition to ethylene, the plasticizer of the present invention also uses highly polar vinyl acetate monomer for copolymerization, which significantly improves the compatibility of the plasticizer with PVC, and the ratio of vinyl acetate to ethylene has a significant effect on the mechanical strength of the plasticizer. If too much vinyl acetate is added, the strength will be insufficient; if too little is added, the elongation will be insufficient due to poor compatibility.

[0008] In some other embodiments of the present invention, the monomer further uses a third crosslinking monomer, and the third crosslinking monomer selected is specifically ethoxyethyl acrylate, propoxylated neopentyl glycol diacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, and dipentaerythritol hexaacrylate. These third crosslinking monomers can increase the crosslinking density because they have a monoene or polyene structure. If the third crosslinking monomer is used in too much amount, there may be a problem of oversulfurization; if it is used in too little amount, there may be a problem of insufficient crosslinking.

[0009] Furthermore, the mass ratio of vinyl acetate, ethylene and the third cross-linking monomer is (40-80):(20-60):(2-10).

[0010] Furthermore, the mass ratio of vinyl acetate, ethylene and the third crosslinking monomer is (40-80):(20-60):(2-6).

[0011] Optimally, the mass ratio of vinyl acetate, ethylene and the third crosslinking monomer is (40-80):(20-60):4.

[0012] Furthermore, the raw materials of the plasticizer also include an initiator and a terminator.

[0013] The initiator provided by the present invention is used to promote the copolymerization reaction when preparing the plasticizer, and the terminator is used to terminate the reaction. Therefore, the type selection and dosage of the initiator and terminator are all well-known / conventional techniques in the art.

[0014] Furthermore, the mass of the initiator accounts for 0.05-0.1% of the total mass of the monomer.

[0015] Preferably, the mass of the initiator accounts for 0.08% of the total mass of the monomers.

[0016] Furthermore, the mass of the terminator accounts for 0.02-0.05% of the total mass of the monomer.

[0017] Preferably, the mass of the terminator accounts for 0.02% of the total mass of the monomer.

[0018] Furthermore, the initiator is at least one of tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, tert-butyl peroxy-2-ethylhexanoate, bis(2-ethylhexyl) peroxydicarbonate, and tert-butyl peroxymaleate.

[0019] Furthermore, the terminator is at least one of p-tert-butylphenol, hydroquinone, p-tert-butylcatechol, 2,6-di-tert-butyl-p-methylphenol, and bisphenol A.

[0020] The present invention also provides a method for preparing the above-mentioned low migration plasticizer, comprising the following steps:

[0021] Adding solvent and other monomers except ethylene under vacuum; introducing pre-ethylene, wherein the amount of pre-ethylene introduced is 55-65% of the total amount of ethylene added; the solvent is an organic solvent having a solubility of ≥0.5% in ethylene gas under the conditions of 1MPa and 30°C and a boiling point not lower than the reaction temperature;

[0022] The initiator is added, and ethylene is subsequently introduced to maintain the pressure and raise the temperature to the reaction temperature to start the reaction. After the reaction is completed, the terminator is added to terminate the reaction, and the plasticizer product is obtained by devolatilization and granulation.

[0023] It should be noted that, in order to improve the conversion rate of the resin, when preparing the plasticizer according to the above method, the solvent generally refers to an organic solvent with good solubility in ethylene gas. At the same time, the solvent is also required to have a boiling point not lower than the reaction temperature (e.g., 80° C.), and it is also required that the solvent does not undergo self-polymerization during the polymerization reaction. As long as the organic solvent meets this requirement, it can be used as the solvent of the present invention.

[0024] Optionally, when preparing the plasticizer, an organic solvent having an ethylene gas solubility of ≥ 0.5% (1 MPa, 30° C.) is selected.

[0025] Furthermore, the mass of the solvent is 0.5-1.2 times the total mass of the monomers.

[0026] Preferably, the mass of the solvent is 0.6-0.8 times the total mass of the monomers.

[0027] Furthermore, the solvent is at least one of tert-butanol, cyclohexane, methanol, n-heptane and dimethyl carbonate.

[0028] Furthermore, in the preparation method of the above-mentioned plasticizer, the process of maintaining pressure and heating to start the reaction is: maintaining the pressure at 55-60 bar, first reacting at 58-62°C for 5.5-6h, and then step-by-step heating by increasing the temperature by 5°C each time, and the reaction time after each heating is 45-60min; until the temperature is increased to 80°C, the reaction is continued for 45-60min.

[0029] Furthermore, the conditions for starting the reaction by maintaining the pressure and raising the temperature are: maintaining the pressure at 60 bar, first reacting at 60° C. for 6 hours, and then step-by-step raising the temperature by 5° C. each time, and the reaction time after each temperature increase is 1 hour; and then continuing the reaction for 1 hour after the temperature reaches 80° C.

[0030] For example, in some embodiments of the present invention, the preparation method of the plasticizer may be specifically as follows:

[0031] (1) Close the reactor and introduce N 2 Replace 3 times and evacuate.

[0032] (2) Use negative pressure to suck in a predetermined amount of solvent and start stirring after the addition is complete.

[0033] (3) A predetermined amount of vinyl acetate monomer is sucked in by negative pressure. If a third cross-linking monomer is used, a predetermined amount of the third cross-linking monomer is also sucked in by negative pressure.

[0034] (4) Charge N 2 Three times, and then vacuum again.

[0035] (5) Add the pre-added ethylene monomer according to the predetermined pre-added amount and raise the temperature to 60°C.

[0036] (6) Add the initiator in the predetermined amount at one time; after adding the initiator, flush the pipeline with solvent.

[0037] (7) The remaining ethylene (post-ethylene monomer) is introduced into the reactor to maintain the pressure, and the pressure is maintained at 60 bar to start the reaction;

[0038] The pressure was kept constant at 60 bar throughout the reaction process. First, the reaction temperature was 60°C from 0 to 360 minutes (6 hours in total) at the beginning of the reaction; then the reaction temperature was 65°C from 360 to 420 minutes; then the reaction temperature was 70°C from 420 to 480 minutes (1 hour in total); then the reaction temperature was 75°C from 480 to 540 minutes (1 hour in total); and finally the reaction temperature was 80°C from 540 to 600 minutes.

[0039] (8) The reaction was completed after 600 min of reaction. The terminator was added to terminate the reaction. The mixture was stirred for 10 min and then discharged.

[0040] (9) Use a devolatilizer to carry out devolatilization granulation, and the devolatilizer temperature is 120-130℃.

[0041] The present invention also provides the use of the low migration plasticizer in the preparation of high molecular polymer materials.

[0042] Furthermore, the high molecular polymer material is a PVC material, and its raw materials include PVC and a plasticizer in a mass ratio of 1:(0.4-1).

[0043] It should be noted that the plasticizer provided by the present invention can be widely used in the synthesis technology of different types of polymer materials that need to improve plasticizing performance, and can improve the flexibility and strength of resins. The flexibility and elongation at break of the polymer material after plasticization modification are improved.

[0044] The type of high molecular polymer can be almost all plastics / resins. For example, the high molecular polymer can be, but is not limited to, high polar polymers such as polyvinyl chloride, polyamide, and polycarbonate.

[0045] Taking the most commonly used PVC material as an example, the application method of the plasticizer provided by the present invention is: in the process of PVC flexibility modification (plasticization), adding different plasticizers of the present invention according to the weight of PVC can reduce the hardness of the product and improve the flexibility, and the addition amount can be adjusted according to the specific hardness requirements.

[0046] It should be noted that in some embodiments of the present invention, when preparing high molecular polymer materials such as PVC materials, in addition to PVC particles and plasticizer particles, common additives in the art may also be added.

[0047] Optionally, the raw materials of the PVC material may also include epoxidized soybean oil, calcium carbonate, stearic acid, a stabilizer, and an external lubricant;

[0048] In some implementation cases of the present invention, based on the total mass of the PVC material, the raw materials of the PVC material may also include 3% epoxidized soybean oil, 20% calcium carbonate, 0.3% stearic acid, 3% stabilizer, and 0.5% external lubricant.

[0049] Compared with the prior art, the invention is advantageous in that: the invention provides a plasticizer for preparing a high molecular polymer material, the plasticizer has good compatibility with PVC, a large molecular weight, good migration resistance, and the prepared high molecular polymer material has better flexibility and higher strength. DETAILED DESCRIPTION

[0050] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0051] In the following specific embodiments of the present invention, the third cross-linking monomer used as a raw material for preparing the plasticizer can be selected from at least one of ethoxyethyl acrylate (Zhuhai Changxing Chemical Company, specification model EM211), propoxylated neopentyl glycol diacrylate (Zhuhai Changxing Chemical Company, specification model EM2251), ethoxylated trimethylolpropane triacrylate (Zhuhai Changxing Chemical Company, specification model EM2387), propoxylated glycerol triacrylate (Zhuhai Changxing Chemical Company, specification model EM2382), and dipentaerythritol hexaacrylate (Zhuhai Changxing Chemical Company, specification model EM2696).

[0052] In the following specific embodiments of the present invention, the raw materials of the low migration plasticizer include monomers, initiators and terminators.

[0053] In some embodiments of the present invention, the monomers are composed of ethylene, vinyl acetate and a third crosslinking monomer, and the mass ratio of vinyl acetate, ethylene and the third crosslinking monomer is (40-80):(20-60):(0-10). That is, in some embodiments, the monomers are composed of ethylene and vinyl acetate, and in other embodiments, the monomers are composed of ethylene, vinyl acetate and a third crosslinking monomer.

[0054] Optionally, the third cross-linking monomer is at least one of ethoxyethyl acrylate, propoxylated neopentyl glycol diacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, and dipentaerythritol hexaacrylate.

[0055] Furthermore, the mass ratio of vinyl acetate, ethylene and the third cross-linking monomer is (40-80):(20-60):(2-10).

[0056] Preferably, the mass ratio of vinyl acetate, ethylene and the third crosslinking monomer is (40-80):(20-60):(2-6).

[0057] Optimally, the mass ratio of vinyl acetate, ethylene and the third crosslinking monomer is (40-80):(20-60):4.

[0058] The solvent used in the present invention has high solubility in ethylene, a boiling point not lower than the reaction temperature (e.g. 80°C), and does not undergo self-polymerization during the polymerization reaction.

[0059] Optionally, when preparing the plasticizer, an organic solvent having an ethylene gas solubility of ≥ 0.5% (1 MPa, 30° C.) is selected.

[0060] In some embodiments of the present invention, the mass of the solvent is 0.5-1.2 times the total amount of the monomers.

[0061] Preferably, the mass of the solvent is 0.6-0.8 times the total mass of the monomers.

[0062] In the following specific implementation manners, the solvent may be specifically selected from at least one of tert-butyl alcohol, cyclohexane, methanol, n-heptane, and dimethyl carbonate.

[0063] The plasticizer provided by the present invention achieves the effect of plasticizing resin by selecting specific monomers as raw materials and selecting special solvents during preparation. That is to say, the above effects are mainly brought about by the specific selection and specific dosage of these specific monomers and solvents.

[0064] However, it should be noted that, in addition to using specific monomers and solvents, the plasticizer provided by the present invention also needs to add initiators and terminators in order to allow the polymerization process of preparing the plasticizer to proceed and terminate rapidly and normally. The type and amount of the initiator and terminator are conventional techniques in the art and do not play a decisive role in the process of achieving the above-mentioned technical effects of the plasticizer.

[0065] In some embodiments of the present invention, the mass of the initiator accounts for 0.05-0.1% of the total mass of the monomers.

[0066] For example, the mass of the initiator accounts for 0.08% of the total mass of the monomers.

[0067] In some embodiments of the present invention, the mass of the terminator accounts for 0.02-0.05% of the total mass of the monomer.

[0068] For example, the mass of the terminator accounts for 0.02% of the total mass of the monomer.

[0069] In some embodiments of the present invention, the initiator is at least one of tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, tert-butyl peroxy-2-ethylhexanoate, bis(2-ethylhexyl) peroxydicarbonate, and tert-butyl peroxymaleate.

[0070] In some implementation cases of the present invention, the terminator is at least one of p-tert-butylphenol, hydroquinone, p-tert-butylcatechol, 2,6-di-tert-butyl-p-methylphenol, and bisphenol A.

[0071] It should be noted that applicable initiators and terminators are not limited to the above-mentioned specific compounds.

[0072] In some embodiments of the present invention, the overall preparation method of the plasticizer is as follows: adding a solvent, vinyl acetate and a third cross-linking monomer under a vacuum environment; the amount of ethylene introduced in advance (mass or volume) is 55-65% of the total amount of ethylene added; adding an initiator, and then introducing ethylene in a post-stage to maintain pressure and increase temperature to start the reaction, and after the reaction is completed, adding the terminator to terminate the reaction, and devolatilizing and granulating to obtain the finished plasticizer.

[0073] In the following specific implementation manner, the initiator is tert-butyl peroxyneodecanoate, and the mass thereof is 0.08% of the total mass of the monomers.

[0074] In the following specific implementation manner, the terminator is p-tert-butylphenol, and the mass thereof is 0.02% of the total mass of the monomers.

[0075] In the plasticizer preparation method provided by the present invention, the process of maintaining pressure and heating to start the reaction is: maintaining the pressure at 55-60 bar, first reacting at 58-62° C. for 5.5-6 hours, and then step-by-step heating by increasing the temperature by 5° C. each time, and the reaction time after each heating is 45-60 minutes; and continuing the reaction for 45-60 minutes after the temperature reaches 80° C.

[0076] Preferably, the conditions for starting the reaction by maintaining pressure and increasing temperature are: maintaining the pressure at 60 bar, first reacting at 60° C. for 6 hours, then increasing the temperature stepwise by 5° C. each time, and the reaction time after each temperature increase is 1 hour; and continuing the reaction for 1 hour after the temperature reaches 80° C.

[0077] For example, in some embodiments of the present invention, the preparation method of the plasticizer may be further specifically as follows:

[0078] (1) Close the reactor and introduce an inert gas (such as N 2 ) Replace 3 times and evacuate.

[0079] (2) Use negative pressure to suck in a predetermined amount of solvent and start stirring after the addition is complete.

[0080] (3) A predetermined amount of vinyl acetate monomer is sucked in by negative pressure. If a third cross-linking monomer is used, a predetermined amount of the third cross-linking monomer is sucked in by negative pressure.

[0081] (5) Charge N 2 Three times, and then vacuum again.

[0082] (5) Add the pre-added ethylene monomer according to the predetermined pre-added amount and raise the temperature to 60°C.

[0083] (6) Add the initiator in the predetermined amount at one time; after adding the initiator, flush the pipeline with solvent.

[0084] (7) The remaining ethylene (post-ethylene monomer) is introduced into the reactor to maintain the pressure, and the pressure is maintained at 60 bar to start the reaction;

[0085] The pressure was kept constant at 60 bar throughout the reaction process. First, the reaction temperature was 60°C from 0 to 360 minutes (6 hours in total) at the beginning of the reaction; then the reaction temperature was 65°C from 360 to 420 minutes; then the reaction temperature was 70°C from 420 to 480 minutes (1 hour in total); then the reaction temperature was 75°C from 480 to 540 minutes (1 hour in total); and finally the reaction temperature was 80°C from 540 to 600 minutes.

[0086] (8) The reaction was completed after 600 min of reaction. The terminator was added to terminate the reaction. The mixture was stirred for 10 min and then discharged.

[0087] (9) Use a devolatilizer to carry out devolatilization granulation, and the devolatilizer temperature is 120-130℃.

[0088] In some specific implementation cases of the present invention, a plasticizer can be used to plasticize a variety of different high molecular polymer materials commonly used in the art using corresponding plasticizing methods. After testing, it was found that for different types of high molecular polymer materials, such as polyvinyl chloride, polyamide, polycarbonate and other high polar polymers, the plasticizer of the present application can achieve good plasticizing effects, better flexibility and higher strength.

[0089] In the following specific embodiments of the present invention, in order to verify the plasticizing effect of plasticizers on high molecular polymer materials, PVC particles are used as research objects and representatives.

[0090] When the plasticizers of the following specific embodiments or comparative examples are used to plasticize the PVC material, the raw materials used, in addition to the PVC particles and plasticizer particles, may also be other components that are customarily used or conventionally added in the industry, such as fillers, stabilizers, lubricants, foaming agents, etc., according to actual production needs, and the plasticization process may be performed using conventional plasticizing methods in the art.

[0091] The following specific embodiments of the present invention mainly study the plasticizing effect of plasticizers on PVC materials. As for other components that are commonly used or conventionally added in the art, their effects are well known, so no separate study has been done and there is no need to do so, and this does not belong to the research focus of the present invention.

[0092] In the following specific implementations of the present invention, the usage ratio of PVC particles to plasticizer particles is 1:(0.25-1), and epoxy soybean oil, calcium carbonate, stearic acid, stabilizer and external lubricant are also selected as raw materials.

[0093] Specifically, in the following specific embodiments, PVC particles are 100% and plasticizer particles are 40-100%.

[0094] In some specific implementation cases of the present invention, the raw materials of the PVC material also include 3-5% epoxidized soybean oil, 20-30% calcium carbonate, 0.2-0.5% stearic acid, 3-5% stabilizer, and 0.3-0.6% external lubricant.

[0095] Specifically, in order to verify the plasticizing effect of plasticizers on PVC, the raw material formula shown in Table 1 below was used for plasticizing treatment.

[0096] Table 1, unit: mass parts (e.g. g)

[0097]

[0098] For the PVC plasticizing formula in Table 1, the specific plasticizing method is as follows: after the above formula is mixed, it is plasticized by refining, and then the performance of the plasticizer is tested by compression molding.

[0099] In the following specific embodiments of the present invention, the performance test items of the plasticizer include Mooney viscosity (ML100°C (1+4)), weight average molecular weight (Mw), tensile strength (MPa) and elongation at break (%).

[0100] In the following specific embodiments of the present invention, when testing the performance of the plasticizer, it is generally used to prepare PVC materials and make test samples, and then the corresponding plasticizing effect test is carried out. The test items include tensile strength (MPa), elongation at break (%), and mobility (%). The test method of mobility is as follows:

[0101] (1) According to the process in Table 2 below, PVC samples were prepared using plasticizers according to the formulation in Table 1.

[0102] Table 2

[0103]

[0104] (2) Cut the above 1 mm PVC film into 10 cm × 10 cm pieces and weigh them. 0 ;

[0105] (3) Place a PE oil absorption specimen block with a length, width and thickness of 20 cm × 20 cm × 0.5 m above and below the sample block to absorb the plasticizer that migrates out of the PVC.

[0106] (4) Add a steel plate with a length, width and thickness of 25 cm × 25 cm × 0.15 cm on the top and bottom, and place a 5 kg weight at the center of the surface of the upper steel plate;

[0107] (5) Place the sample and the weight in a 60°C oven for 24 hours to simulate the precipitation of plasticizer; take out the sample, wipe the surface of the PVC film clean, and weigh the weight m 1 The mobility W is calculated as: W = [(m 0 -m 1 ) / m 0 ]×100%.

[0108] Embodiment 1:

[0109] The preparation method of the plasticizer provided in this embodiment is as follows:

[0110] S1, close the reactor, N 2 Replace 3 times and evacuate.

[0111] S2. Use negative pressure to suck in a specific solvent, and add 63 parts (parts by mass, the same below). Start stirring after the addition is completed.

[0112] S3. Use negative pressure to suck in vinyl acetate monomer, the added amount is 60 parts. Use negative pressure to suck in propoxylated glyceryl triacrylate monomer (third cross-linking monomer), the added amount is 4 parts.

[0113] S4, then N 2 Fill three times and vacuum once.

[0114] S5. Start adding pre-ethylene monomer, the pre-introduction amount is 20 parts, and start heating to 60°C.

[0115] S6. Add tert-butyl peroxyneodecanoate (initiator) at one time, the addition amount is 0.08 parts. After the initiator is added, the pipeline needs to be flushed with dimethyl carbonate (solvent).

[0116] S7, post-ethylene is used to maintain pressure, the amount of post-ethylene is 16 parts, and the pressure is maintained at 60 bar to start the reaction. The pressure is maintained at 60 bar, and the reaction temperature is 60°C for the first 0-360 minutes (6 hours in total), 65°C for the first 360-420 minutes (1 hour in total), 70°C for the first 420-480 minutes (1 hour in total), 75°C for the first 480-540 minutes (1 hour in total), and 80°C for the first 540-600 minutes (1 hour in total).

[0117] S8. The reaction was completed at the 600th minute, and 0.02 parts of p-tert-butylphenol (terminator) was added, and the mixture was stirred for 10 minutes before unloading.

[0118] S9. Use a devolatilizer to carry out devolatilization granulation, and the temperature of the devolatilizer is 120-130°C.

[0119] Test Example 1: Effect of the Type of the Third Crosslinking Monomer on the Performance of the Plasticizer

[0120] The following Examples 2-6 and Comparative Example 1 use the same preparation method as Example 1 to prepare plasticizers. The only difference in Comparative Example 1 is that a different third crosslinking monomer is selected. Compared with Example 1, Example 6 does not add any third crosslinking monomer, the mass of vinyl acetate and the ethylene introduced in the front are the same as in Example 1, and the mass of the ethylene introduced in the rear is 20 parts. Since Example 6 does not use the third crosslinking monomer, when the method of Example 1 is used to prepare the plasticizer, step S3 only needs to add vinyl acetate.

[0121] The performance parameters of each plasticizer and the plasticizing effect on PVC materials were tested, as shown in Table 3 below.

[0122] Table 3

[0123]

[0124] As can be seen from the above table 3, when only ethylene monomer and vinyl acetate monomer are adopted, without any third cross-linking monomer, the plasticized modified product tensile strength, elongation at break and mobility will be significantly affected, causing the plasticized modified PVC performance parameters to significantly decline. Generally, the PVC product elongation without any plasticizer cannot reach 100%, and the plasticizer of embodiment 6 invention makes the PVC plasticized modified product elongation reach 222%. This shows that for PVC material, the plasticizer of embodiment 6 invention also has good plasticizing effect. When adopting other third monomer lauric acid acrylate, the performance improvement rate of plasticized modified product tensile strength, elongation at break and mobility is not ideal.

[0125] Test Example 2: Effect of different amounts of the third monomer on plasticizer performance and PVC plasticization effect

[0126] Examples 6-9 Plasticizers were prepared according to the method of Example 1, except that the addition amounts of ethylene and vinyl acetate were kept unchanged, and the addition amount of the third monomer was changed, so that the addition amount (mass parts) of the third monomer was 0, 2, 6 and 10 parts respectively. The performance parameters are shown in Table 4 below.

[0127] Table 4

[0128]

[0129] From the data in Table 4, we can see that the amount of the third monomer added will affect the plasticization effect of PVC. As the proportion of the third monomer increases, the strength of the product is improved. When the amount of the third monomer increases from 6 to 10 parts, the increase in strength tends to be gentle, and the elongation of the product decreases. In summary, when the amount of the third cross-linking monomer is 2-10 parts, the tensile strength and elongation of the plasticized modified product are significantly improved compared with the plasticized modified product without adding the third monomer.

[0130] Preferably, when the amount of the third cross-linking monomer is 2-6 parts, the tensile strength and elongation of the plasticized modified product tend to be flat.

[0131] Optimally, when the amount of the third cross-linking monomer in Example 1 is 4 parts, the tensile strength and elongation of the plasticized modified product reach the optimal values.

[0132] Test Example 3: Effects of different amounts of ethylene and vinyl acetate on plasticizer performance and PVC plasticization effect

[0133] The plasticizer was prepared according to the method of Example 1, the only difference being that the amount of ethylene and vinyl acetate added was changed, but the total amount of ethylene, vinyl acetate and the third monomer remained unchanged. The corresponding plasticizers and the formula of Table 1 were used to prepare PVC samples. In Table 5, the amount of ethylene added in Example 10 was 56 parts by mass, and the amount of vinyl acetate monomer added was 40 parts by mass; the amount of ethylene added in Example 11 was 16 parts by mass, and the amount of vinyl acetate monomer added was 80 parts by mass. The amount of ethylene added in Comparative Example 2 was 11 parts by mass, and the amount of vinyl acetate monomer added was 85 parts by mass; the amount of ethylene added in Comparative Example 3 was 66 parts by mass, and the amount of vinyl acetate monomer added was 30 parts by mass.

[0134] Table 5

[0135]

[0136] From the data in Table 5, it can be seen that the plasticizers of the present invention with different vinyl acetate contents have a significant effect on the tensile strength and elongation at break of the plasticized modified products. If the vinyl acetate content is too high, the tensile strength of the product will be reduced, and if the vinyl acetate content is too low, the elongation at break of the product will be reduced.

[0137] Test Example 4: Effects of different solvents on plasticizer performance

[0138] As shown in Table 6 below, the following examples use the same preparation method as Example 1 to prepare plasticizers, the only difference being that different solvents are used. At the same time, the polymerization conversion rates of the plasticizers of Preparation Examples 1, 12-15 and Comparative Examples 4-8 are detected and calculated.

[0139] Table 6

[0140]

[0141]

[0142] From the results of Table 6 above, it can be seen that the solvent has an effect on the polymerization conversion rate of the plasticizer of the present invention. Comparative Examples 1, 12-15 and Comparative Example 8 show that the polymerization conversion rate of 1,2-propylene glycol, which has a lower solubility in ethylene, is significantly lower than that of other solvents with higher solubility in ethylene. Because ethylene is a gas under the reaction pressure, if it cannot be dissolved in the solvent, it cannot participate in the reaction. Therefore, the higher the solubility in ethylene, the more conducive it is to improving the polymerization conversion rate. However, from the polymerization conversion rates of Comparative Examples 4-6, it can be seen that although isobutanol, n-hexane and diethyl carbonate all have good solubility in ethylene, the conversion rate is not necessarily high. This shows that the solubility in ethylene is only a necessary condition for selecting a solvent, but not a sufficient condition.

[0143] By comparing Examples 1, 12-15 and Comparative Example 7, it can be seen that solvents such as tetrahydrofuran, which are prone to self-polymerization, are not suitable for the polymerization solvent of the present invention.

[0144] Test Example 5: Effect of plasticizer addition on PVC plasticization performance

[0145] According to the method of Example 1, a plasticizer was prepared, and a PVC sample was prepared using the plasticizer. The difference between the formulas of Examples 16-19 and Comparative Examples 9-10 and Table 1 is the amount of the plasticizer used; Comparative Example 11 did not use the plasticizer prepared in Example 1, but used dioctyl phthalate (DOP) as the plasticizer. The specific amount of plasticizer used and the results are shown in Table 7 below.

[0146] Table 7

[0147]

[0148] As can be seen from Table 7 above, by comparing the mobility of plasticizers, the mobility of the plasticizer of the present invention is much lower than that of DOP plasticizer. Adjusting the amount of plasticizer added will have a significant impact on the plasticizing effect of PVC. However, when the amount of plasticizer added is too low, the hardness of the PVC product is too large and the elongation is insufficient; when the amount of plasticizer added is too high, the strength of the PVC product will be reduced.

[0149] In summary, the present invention makes the prepared plasticizer have the effects of low migration and high mechanical properties through the synergistic effect of ethylene, vinyl acetate and the third crosslinking monomer. The plasticizer is used in the plasticization process of polymer materials such as PVC to improve the flexibility of plastic products while maintaining high mechanical properties.

[0150] The above specific embodiments describe the implementation of the present invention in detail, but the present invention is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concept of the present invention, the technical solution of the present invention can be modified and changed in many simple ways, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. Application of a low migration plasticizer, characterized in that: For preparing PVC material, the raw materials include PVC and plasticizer in a mass ratio of 1:(0.4-1); the plasticizer raw materials include monomers, initiators and terminators, the monomers are composed of ethylene, vinyl acetate and a third cross-linking monomer, and the mass ratio of vinyl acetate, ethylene and the third cross-linking monomer is (40-80):(20-60):(2-10); The third cross-linking monomer is at least one of ethoxyethyl acrylate, propoxylated neopentyl glycol diacrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, and dipentaerythritol hexaacrylate.

2. The use of the low migration plasticizer according to claim 1, characterized in that: The mass ratio of vinyl acetate, ethylene and the third cross-linking monomer is (40-80):(20-60):(2-6).

3. The use of the low migration plasticizer according to claim 2, characterized in that: The mass ratio of vinyl acetate, ethylene and the third cross-linking monomer is (40-80):(20-60):

4.

4. The method for preparing the low migration plasticizer according to any one of claims 1 to 3, characterized in that: The following steps are involved: Adding solvent and other monomers except ethylene under vacuum; Pre-ethylene is introduced, and the amount of pre-ethylene introduced is 55-65% of the total amount of ethylene added; the solvent is an organic solvent with a solubility of ethylene gas of ≥0.5% under the conditions of 1MPa and 30°C and a boiling point not lower than the reaction temperature; The initiator is added, and ethylene is subsequently introduced to maintain the pressure and raise the temperature to the reaction temperature to start the reaction. After the reaction is completed, the terminator is added to terminate the reaction, and the plasticizer product is obtained by devolatilization and granulation.

5. The preparation method according to claim 4, characterized in that: The mass of the solvent is 0.5-1.2 times the total mass of the monomers.

6. The preparation method according to claim 4, characterized in that: The process of maintaining pressure and heating to start the reaction is: maintain the pressure at 55-60 bar, first react at 58-62°C for 5.5-6h, then step-by-step increase of temperature by 5°C each time, and the reaction time after each temperature increase is 45-60min; continue to react for 45-60min after the temperature reaches 80°C.

7. The preparation method according to claim 6, characterized in that: The conditions for starting the reaction by maintaining the pressure and raising the temperature are as follows: maintaining the pressure at 60 bar, first reacting at 60° C. for 6 hours, then raising the temperature stepwise by 5° C. each time, and the reaction time after each temperature increase is 1 hour; and then continuing the reaction for 1 hour after the temperature reaches 80° C.

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