A heat-resistant and yellowing-resistant PET masterbatch and its preparation method

Abstract

This application relates to the technical field of plastic materials. More specifically, it relates to a heat-resistant and yellowing-resistant PET masterbatch and a preparation method thereof, which are made from raw materials including the following parts by weight: 45-50 parts of terephthalic acid; 35.8-42.8 parts of ethylene glycol; 2.4-3.3 parts of hydroxyl-terminated polybutadiene; 0.5-1.3 parts of fluorinated acrylate; 0.68-1.5 parts of additives. In this application, hydroxyl-terminated polybutadiene and fluorinated acrylate are used as modifiers. Carbon-carbon double bonds are introduced through hydroxyl-terminated polybutadiene, and then fluorine-containing groups are introduced into the polyester long chain through the addition reaction of carbon-carbon double bonds. The fluorine-containing groups have a shielding effect, and the addition of carbon-carbon double bonds can increase the crosslinking density of the PET masterbatch. Under the action of the fluorine-containing groups and carbon-carbon double bonds, the ester groups of the PET masterbatch are protected and not easily oxidized and decomposed, having good yellowing resistance; the ester groups are also not easily broken and hydrolyzed, and excellent high-temperature and hydrolysis resistance is also possessed.

Description

Technical Field

[0001] This application relates to the technical field of plastic materials. More specifically, it relates to a temperature-resistant and yellowing-resistant PET masterbatch and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate (abbreviation: PET) is a kind of thermoplastic polyester, which has good wear resistance, high light transmittance and electrical insulation. It can be used to prepare products such as packaging films, fibers, containers, etc., and has good market prospects.

[0003] Pure PET is formed by polycondensation of terephthalic acid and ethylene glycol. Since the pure PET resin has poor yellowing resistance, light stabilizers are generally used in related technologies to improve the weather resistance of pure PET materials. Light stabilizers include ultraviolet absorbers and hindered amine light stabilizers. The former can absorb ultraviolet light and convert it into heat energy and dissipate it; the latter mainly captures free radicals to prevent deterioration. However, the alkaline hindered amine light stabilizer may be ineffective for acidic polymers, resulting in poor modification effect of the light stabilizer on pure PET materials.

[0004] In view of the above situation, the applicant of this application tried to add hindered amine light stabilizer to pure PET material. After aging for 1000 h, the yellow index of the PET material was detected, and its yellow index was as high as 5.06. Therefore, the applicant seeks a new PET modification method, which can effectively improve the yellowing resistance of PET resin and reduce the yellow index of PET material to below 3.00. Summary of the Invention

[0005] This application provides a temperature-resistant and yellowing-resistant PET masterbatch and a preparation method thereof. After aging for 1000 h, the yellow index of this PET masterbatch is reduced to below 3.00 after detection, and it has excellent yellowing resistance.

[0006] In the first aspect, a temperature-resistant and yellowing-resistant PET masterbatch provided by this application adopts the following technical solution:

[0007] A temperature-resistant and yellowing-resistant PET masterbatch is made from raw materials including the following parts by weight:

[0008] Terephthalic acid: 45 - 50 parts;

[0009] Ethylene glycol: 35.8 - 42.8 parts;

[0010] Hydroxyl-terminated polybutadiene: 2.4 - 3.3 parts;

[0011] Fluorinated acrylate: 0.5 - 1.3 parts;

[0012] Auxiliary agent: 0.68 - 1.5 parts.

[0013] By adopting the above technical solution, the hydroxyl-terminated polybutadiene is capped with hydroxyl groups, and its main chain structure contains carbon-carbon double bonds; the hydroxyl groups of the hydroxyl-terminated polybutadiene can react with the carboxyl groups of terephthalic acid to introduce carbon-carbon double bonds into the polyester long chain, and one end of the fluorinated acrylate contains a carbon-carbon double bond and the other end contains a fluorine group. The fluorinated acrylate can undergo a double bond addition reaction, so that a fluorine group is introduced into the polyester long chain, and a PET masterbatch with a high crosslinking density and stable performance is obtained.

[0014] The shielding effect of the fluorine group is strong, and the fluorine group can prevent peroxy free radicals from attacking the ester groups of the PET masterbatch, reducing the possibility of ester bond breakage; at the same time, the addition reaction of the carbon-carbon double bond increases the crosslinking density of the PET masterbatch, thereby increasing the difficulty of ester bond breakage in the PET masterbatch, and can effectively improve the yellowing resistance of the PET masterbatch. And, since most of the carbon-carbon double bonds form saturated alkane chains through addition reactions, the unreacted carbon-carbon double bonds have little effect on the yellowing resistance of the PET masterbatch.

[0015] Secondly, due to the high crosslinking density of the PET masterbatch and the shielding effect of the fluorine group in the PET masterbatch, on the one hand, it can ensure the stable existence of the ester bonds on the PET masterbatch chain segments and is not easy to break in a high-temperature and high-humidity environment, thereby effectively improving the heat resistance of the PET masterbatch; on the other hand, it can significantly reduce the surface free energy of the PET masterbatch and hinder the invasion of moisture, thereby effectively improving the hydrolysis resistance of the PET masterbatch.

[0016] In addition, the PET masterbatch prepared in this application contains fluorine groups, resulting in a reduced crystallization enthalpy, a decreased crystallization ability, an enhanced chain segment mobility, while ensuring an increase in the tensile strength of the PET masterbatch, enhancing its elongation at break, and thus improving the mechanical properties of the PET masterbatch.

[0017] Preferably, the weight ratio of the hydroxyl-terminated polybutadiene to terephthalic acid is (0.06 - 0.07):1.

[0018] Preferably, the weight ratio of the fluorinated acrylate to terephthalic acid is (0.015 - 0.02):1.

[0019] By adopting the above technical solution, the weight parts of the hydroxyl-terminated polybutadiene and the fluorinated acrylate are adjusted. On the one hand, as many carbon-carbon double bonds as possible are made to react, while increasing the crosslinking density, further reducing the influence of the carbon-carbon double bonds of the unreacted raw materials; on the other hand, increasing the grafting rate of the fluorine group and further increasing the fluorine content in the PET masterbatch, so that the yellowing resistance, high-temperature hydrolysis resistance and mechanical properties of the PET masterbatch are significantly improved.

[0020] Preferably, the number average molecular weight of the hydroxyl-terminated polybutadiene is 3.0×10 3 ~3.6×103 。

[0021] By adopting the above technical solution, the number-average molecular weight of the hydroxyl-terminated polybutadiene is moderate, and the double bond content is moderate. It can reduce the content of unsaturated double bonds on the PET masterbatch while ensuring the full introduction of fluorine-containing groups into the PET masterbatch, thereby reducing the impact of unsaturated double bonds on the yellowing resistance of the PET masterbatch.

[0022] Preferably, the fluorinated acrylate is one or more of perfluoroalkyl ethyl methacrylate, 2-(perfluorobutyl)ethyl methacrylate, 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl methacrylate.

[0023] By adopting the above technical solution, the fluorinated acrylate includes but is not limited to 2-(perfluorododecyl)ethyl acrylate, 2-(perfluorobutyl)ethyl acrylate, perfluoroalkyl ethyl methacrylate, etc.; compared with 2-(perfluorododecyl)ethyl acrylate, the fluorine chain lengths of 2-(perfluorobutyl)ethyl acrylate, perfluoroalkyl ethyl methacrylate, 2-(perfluorobutyl)ethyl methacrylate, and 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl methacrylate are moderate and more stable, which helps to improve the mechanical properties and yellowing resistance of the PET masterbatch.

[0024] More preferably, the fluorinated acrylate is 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl methacrylate.

[0025] By adopting the above technical solution, 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl methacrylate also contains a hydroxyl group, which can improve the crosslinking strength of the PET masterbatch and is also beneficial for the fluorine-containing group to play a better shielding role on the phenyl group of the PET masterbatch.

[0026] Optionally, the auxiliary agent is one or more of an antioxidant, a light stabilizer, and a catalyst.

[0027] The types of the antioxidant include but are not limited to aromatic amines and hindered phenols;

[0028] The types of the light stabilizer mainly include o-hydroxybenzophenones, benzotriazoles, salicylate esters, triazines, substituted acrylonitriles, etc.;

[0029] The catalyst includes but is not limited to sodium persulfate, potassium persulfate, cobalt acetate, nickel, etc.

[0030] In a second aspect, the present application provides a preparation method of a temperature-resistant and yellowing-resistant PET masterbatch, adopting the following technical solution:

[0031] A preparation method of a temperature-resistant and yellowing-resistant PET masterbatch includes the following steps:

[0032] Mix terephthalic acid, ethylene glycol, and hydroxyl-terminated polybutadiene to obtain Reaction System 1;

[0033] Mix fluorinated acrylate and additives to obtain Reaction System 2;

[0034] Mix and cast Reaction System 1 and Reaction System 2, and then through curing, crushing, and extrusion pelletizing to obtain a temperature-resistant and yellowing-resistant PET masterbatch.

[0035] By adopting the above technical solution, the preparation process of the PET masterbatch is simple, and the obtained product has excellent yellowing resistance, which is solved from the root cause.

[0036] In summary, this application has at least the following beneficial effects:

[0037] In this application, hydroxyl-terminated polybutadiene and fluorinated acrylate are used as modifiers. Carbon-carbon double bonds are introduced through hydroxyl-terminated polybutadiene, and then through the addition reaction of carbon-carbon double bonds, fluorine-containing groups are introduced into the polyester long chain. The fluorine-containing groups have a shielding effect, and the addition of carbon-carbon double bonds can increase the crosslinking density of the PET masterbatch. Under the action of the fluorine-containing groups and carbon-carbon double bonds, the ester groups of the PET masterbatch are protected, not easily oxidized and decomposed, and have good yellowing resistance; the ester groups are also not easily broken and hydrolyzed, and also have excellent high-temperature and hydrolysis resistance. Detailed Embodiments

[0038] In related technologies, generally, light stabilizers are added to pure PET materials as modifiers. However, the hindered amine substances in the light stabilizers are alkaline and are easily inactivated in the presence of terephthalic acid. Therefore, through actual detection, the applicant found that: when the hindered amine light stabilizer is added to pure PET materials, after aging for 1000 h, the yellow index of the PET materials is as high as 5.06. The yellowing resistance of the PET materials is not good.

[0039] Based on the above situation, the applicant explored the structure of the PET materials and found that: carbon-carbon double bonds can be introduced first through an esterification reaction, and then through the addition of carbon-carbon double bonds, so as to introduce fluorine-containing side chains on the polyester main chain to obtain a PET masterbatch with a high crosslinking density and a high fluorine content. The PET masterbatch obtained in this application also undergoes aging detection, and its yellow index can be reduced to below 3.00, having excellent yellowing resistance, thus successfully solving the problem.

[0040] In addition, due to the increase in crosslinking density and the shielding effect of the fluorine-containing side chains, the ester bonds of the PET masterbatch are not easily broken, and it has excellent high-temperature resistance and hydrolysis resistance at the same time. Secondly, due to the decrease in the crystallization performance of the PET masterbatch, its elongation at break is high and its mechanical properties are excellent.

[0041] The present application will be further described in detail below with reference to examples and comparative examples.

[0042] Unless otherwise specified, the raw materials used in the examples of the present application are as follows.

[0043] Hydroxyl-terminated polybutadiene: all sourced from Tianyuan Aviation Materials;

[0044] Type I: number average molecular weight 3.8×10 3 ~4.6×10 3 , hydroxyl value 0.48 mmol / g;

[0045] Type III: number average molecular weight 3.0×10 3 ~3.6×10 3 , hydroxyl value 0.70 mmol / g;

[0046] Type IV: number average molecular weight 2.7×10 3 ~3.0×10 3 , hydroxyl value 0.80 mmol / g;

[0047] Examples

[0048] Example 1

[0049] A temperature-resistant and yellowing-resistant PET masterbatch is prepared according to the following steps:

[0050] Take 45 parts by weight of terephthalic acid, 35.8 parts by weight of ethylene glycol, and 2.4 parts by weight of hydroxyl-terminated polybutadiene (Type I), heat to 80°C, stir for 1 h while maintaining the temperature, and then add 0.004 parts by weight of potassium persulfate as a catalyst to obtain Reaction System 1;

[0051] Take 0.8 parts by weight of 2-(perfluorododecyl)ethyl acrylate, 0.34 parts by weight of antioxidant Basf1010, and 0.34 parts by weight of light stabilizer 622, blend them, stir for 45 min at 80°C to obtain Reaction System 2;

[0052] Mix and pour Reaction System 1 and Reaction System 2, control the pouring temperature at 80°C; connect the poured material into a tray with a length, width, and height of 55 cm×80 cm×8 cm, start timing, and control the weight of each tray at 5 kg;

[0053] Then, it is transported through a tunnel to a curing room for curing. The curing temperature is 80°C and the curing time is 96 h; take out the cured block product, send it to a low-noise crusher for crushing, and control the particle size of the crushed product within 10 mm uniformly; feed the crushed product into an extruder, control the screw speed at 300 r / min, control the zone temperature at 220°C, and after the material is extruded, connect it to an underwater pelletizer with a constant temperature of 10°C for pelletizing;

[0054] The pelletized particles are transported to a fluidized bed at a temperature of 80 °C for 30 minutes, and then transferred to a drying tower at 100 °C for drying for 120 minutes to obtain a temperature-resistant and yellowing-resistant PET masterbatch.

[0055] Examples 2-9

[0056] A temperature-resistant and yellowing-resistant PET masterbatch, which is different from Example 1 in that the composition of the PET masterbatch is different, as shown in Table 1 below:

[0057] Table 1. Composition of PET masterbatch

[0058] Composition / / parts by weight Example 1 Example 2 Example 3 Example 4 Example 5 Terephthalic acid 45 46 50 46 46 Ethylene glycol 35.8 40.0 42.8 40.0 40.0 Hydroxyl-terminated polybutadiene (Type I) 2.4 2.4 2.4 2.76 3.22 2-(Perfluorododecyl)ethyl acrylate 0.5 0.5 0.5 0.5 0.5 Antioxidant Basf1010 0.34 0.5 0.75 0.5 0.5 Light stabilizer 622 0.34 0.5 0.75 0.5 0.5 Composition / / parts by weight Example 6 Example 7 Example 8 Example 9 Terephthalic acid 46 46 46 46 Ethylene glycol 40.0 40.0 40.0 40.0 Hydroxyl-terminated polybutadiene (Type I) 3.3 3.22 3.22 3.22 2-(Perfluorododecyl)ethyl acrylate 0.5 0.69 0.92 1.3 Antioxidant Basf1010 0.5 0.5 0.5 0.5 Light stabilizer 622 0.5 0.5 0.5 0.5

[0059] Examples 10-11

[0060] A temperature-resistant and yellowing-resistant PET masterbatch, which is different from Example 8 in that the number-average molecular weight of the hydroxyl-terminated polybutadiene used, the specific types and the corresponding molecular weights are as follows:

[0061] In Example 10, hydroxyl-terminated polybutadiene type III is used to replace hydroxyl-terminated polybutadiene type I in equal weight parts;

[0062] In Example 11, hydroxyl-terminated polybutadiene type IV is used to replace hydroxyl-terminated polybutadiene type I in equal weight parts.

[0063] Examples 12-14

[0064] A temperature-resistant and yellowing-resistant PET masterbatch, which is different from Example 10 in that the types of polyisocyanates used are different, and the specific types are as follows:

[0065] In Example 12, perfluoroalkyl ethyl methacrylate is used to replace 2-(perfluorododecyl)ethyl acrylate in equal weight parts;

[0066] In Example 13, 2-(perfluorobutyl)ethyl methacrylate is used to replace 2-(perfluorododecyl)ethyl acrylate in equal weight parts;

[0067] In Example 14, 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl methacrylate is used to replace 2-(perfluorododecyl)ethyl acrylate in equal weight parts.

[0068] Comparative examples

[0069] Comparative examples 1-3

[0070] A PET masterbatch, which is different from Example 1 in that the composition of the PET masterbatch is different, and the specific composition is shown in Table 2 below.

[0071] Table 2. Composition of PET masterbatch

[0072] Composition / / parts by weight Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Terephthalic acid 45 45 45 45 Ethylene glycol 35.8 35.8 35.8 35.8 Hydroxyl-terminated polybutadiene (Type I) 2.4 / 2.4 / 2-(Perfluorododecyl)ethyl acrylate 0.5 / / / 3-(Perfluoro-5-methylhexyl)-2-hydroxypropyl methacrylate / / / 2.9 Antioxidant Basf1010 0.34 1.79 0.79 0.34 Light stabilizer 622 0.34 1.79 0.79 0.34

[0073] For the performance detection test, the PET masterbatches prepared in Examples 1-14 and Comparative Examples 1-3 were extruded, and 1×10 cm long strip samples were cut according to the standard for the following detections:

[0074] Mechanical properties: The strip samples were subjected to a tensile test using a tensile testing machine at a test speed of (100±10) mm / min, and the tensile strength and elongation at break were calculated.

[0075] Anti-yellowing property: According to the detection method described in ASTM G154-16, an aging experiment was carried out using a QUV ultraviolet accelerated aging test machine, and the yellow index was calculated.

[0076] Hydrolysis resistance: A double 85 test was carried out for 800 h, and the grades are as follows:

[0077] Grade A: No hydrolysis and fogging phenomenon, and no pits or other defects appear on the surface after wiping;

[0078] Grade B: Slight hydrolysis and fogging occur, and a very small number of tiny pits or other defects appear on the surface after wiping;

[0079] Grade C: Slight hydrolysis and fogging occur, and some tiny pits or other defects appear on the surface after wiping;

[0080] Grade D: Obvious hydrolysis and fogging occur, and obvious pits or other defects appear on the surface after wiping.

[0081] High and low temperature resistance: The strip samples were placed in a temperature change environment of -40°C to 80°C for detection for 800 h, and the grades are as follows;

[0082] Grade A: No swelling or dissolution phenomenon, and no pits or other defects appear on the surface after wiping;

[0083] Grade B: Slight swelling and dissolution occur, and a very small number of tiny pits or other defects appear on the surface after wiping;

[0084] Grade C: Slight swelling and dissolution occur, and some tiny pits or other defects appear on the surface after wiping;

[0085] Grade D: Obvious swelling and dissolution occur, and obvious pits or other defects appear on the surface after wiping.

[0086] Test results

[0087] Table 3. Performance detection results of Examples 1-14 and Comparative Examples 1-3

[0088]

[0089]

[0090] Combined with Example 1 and Comparative Examples 1-3 and in combination with Table 3, it can be seen that:

[0091] In Comparative Example 1, only traditional antioxidants and hindered amine light stabilizers were used, and the modification effect on PET was poor. Its yellowing index was as high as 5.06, and it was probably due to the poor compatibility between additives such as light stabilizers and polyester, resulting in a decline in mechanical properties.

[0092] In Comparative Example 2, hydroxyl-terminated polybutadiene, antioxidants, and light stabilizers were used. However, the double bond content in the hydroxyl-terminated polybutadiene was too high, resulting in the antioxidant and anti-aging effect on the PET masterbatch being less than the oxidation effect of the unsaturated double bonds in the hydroxyl-terminated polybutadiene even though antioxidants and light stabilizers were present in the raw materials. And although it could increase the crosslinking density of the PET masterbatch to a certain extent, its improvement effect on hydrolysis resistance and high-temperature resistance was weak.

[0093] In Comparative Example 3, only acrylate containing both hydroxyl and fluorine functional groups was used. Although 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl methacrylate could be grafted onto the polyester main chain through the hydroxyl group, due to the influence of the fluorine functional group, this grafting rate was extremely low, and the improvement of the yellowing resistance performance of the PET masterbatch was not obvious.

[0094] In Example 1, hydroxyl-terminated polybutadiene and fluorinated acrylate were used simultaneously, and there was a synergistic effect between the two in the modification of PET, which could significantly improve the mechanical properties, yellowing resistance, high-temperature resistance, and hydrolysis resistance of the PET masterbatch.

[0095] Combined with Application Examples 1-9 and in combination with Table 3, it can be seen that only when the ratio of hydroxyl-terminated polybutadiene to fluorinated acrylate is appropriate can good yellowing resistance and high-temperature resistance be obtained simultaneously.

[0096] Combined with Application Examples 10 and 12 and in combination with Table 3, it can be seen that different types of fluorinated acrylates have a greater impact on the properties of the PET masterbatch; among them, fluorinated acrylates containing hydroxyl groups have a better improvement effect on the properties of the PET masterbatch.

[0097] This specific embodiment is only an interpretation of the present application, and it is not a limitation of the present application. Those skilled in the art can make modifications without creative contributions to this embodiment according to needs after reading this specification, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A temperature-resistant and yellowing-resistant PET masterbatch, characterized in that, It is made from raw materials including the following parts by weight: Terephthalic acid: 45 - 50 parts; Ethylene glycol: 35.8 - 42.8 parts; Hydroxyl-terminated polybutadiene: 2.4 - 3.3 parts; Fluorinated acrylate: 0.5 - 1.3 parts; Auxiliary agent: 0.68 - 1.5 parts; The preparation method of the temperature-resistant and yellowing-resistant PET masterbatch includes the following steps: Carry out copolymerization of terephthalic acid, ethylene glycol and hydroxyl-terminated polybutadiene to obtain reaction system one; Blend the fluorinated acrylate and the auxiliary agent to obtain reaction system two; Mix and pour reaction system one and reaction system two, and then through aging, crushing and extrusion granulation to obtain the temperature-resistant and yellowing-resistant PET masterbatch.

2. The heat-resistant and yellowing-resistant PET masterbatch according to claim 1, wherein: The weight ratio of the hydroxyl-terminated polybutadiene to terephthalic acid is (0.06 - 0.07):

1.

3. A heat-resistant and yellowing-resistant PET masterbatch according to claim 1, characterized in that: The weight ratio of the fluorinated acrylate to terephthalic acid is (0.015 - 0.02):

1.

4. A heat-resistant and yellowing-resistant PET masterbatch according to claim 1, characterized in that: The number-average molecular weight of the said hydroxyl-terminated polybutadiene is 3.0×10 3 ~3.6×10 3 .

5. A heat-resistant and yellowing-resistant PET masterbatch according to claim 1, characterized in that: The fluorinated acrylate is one or more of perfluoroalkyl ethyl methacrylate, 2-(perfluorobutyl)ethyl methacrylate, 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl methacrylate.

6. The heat-resistant and yellowing-resistant PET masterbatch according to claim 1, characterized in that: The fluorinated acrylate is 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl methacrylate.

7. The temperature-resistant and yellowing-resistant PET masterbatch according to claim 1, wherein: The auxiliary agent is one or more of antioxidant, light stabilizer, catalyst.

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