A yellowing inhibitor, its preparation method and application in polyester polymer materials

Abstract

This invention belongs to the field of special additives technology, and discloses an anti-yellowing agent, its preparation method, and its application in polyester polymer materials. The anti-yellowing agent is composed of the following components in the indicated mass percentages: hindered phenolic primary antioxidant: 0.1%–30%, phosphite auxiliary antioxidant: 20%–90%, oleophilic nano-titanium dioxide powder: 0.1%–10%, ultrafine hydrotalcite powder: 0.1%–10%, and calcium stearate powder: 0.1%–5%. The anti-yellowing agent of this invention can simultaneously solve the problems of yellowing due to thermo-oxidative aging of polyester polymer materials such as BOPET film, yellowing during recycled material processing, and yellowing due to gas fumigation during storage and transportation. It has good anti-yellowing effect, strong versatility, is economical in cost, has a simple processing method, stable performance, is convenient to use, and has broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of special additives technology, specifically relating to an anti-yellowing agent, its preparation method, and its application in polyester polymer materials. Background Technology

[0002] BOPET film and other polyester polymer materials belong to the new materials industry, a strategic emerging industry that is receiving key support from the state. Downstream industries for BOPET include numerous industrial applications such as new energy, optoelectronic displays, and electronics. In recent years, with the expansion of downstream applications of BOPET in China, BOPET film has been widely used in industries such as release liner films, solar backsheets, optical films, window films, and flame-retardant films, making it a functional film material with very broad prospects.

[0003] BOPET film is often required to have high transparency in downstream applications, and it must not yellow during processing or storage. Therefore, studying the yellowing phenomenon of BOPET during processing and storage and proposing cost-effective technical solutions is a very meaningful task.

[0004] The main reasons why BOPET film is prone to yellowing during processing and storage include: (1) BOPET processing temperature is generally high, often exceeding 260°C. Under high temperature, high pressure and high shear, thermo-oxidative aging is likely to occur, resulting in yellowing of the material during processing; (2) Some BOPET film processing plants often add a certain proportion of recycled PET material during production to reduce costs in specific application areas. Since recycled PET material contains more small molecules and broken chains, it is prone to yellowing during processing; (3) BOPET film is prone to yellowing due to gas fumes during storage and transportation, resulting in yellowing of the surface of the finished BOPET product.

[0005] In response to the yellowing problem of BOPET during processing and storage, the main technical solutions currently available in the industry are as follows: (1) For some low-end and mid-range applications, many BOPET manufacturers will directly mix a certain proportion of blue or purple pigment into PET to reduce the yellowing problem during the processing of BOPET film; (2) In response to the thermo-oxidative aging of BOPET caused by high temperature, high pressure, and high shear during processing, some BOPET film manufacturers will add some main antioxidants and auxiliary antioxidants, such as 1010, 1076, and 168. Such cases can be found in many patents and documents; (3) In response to the yellowing problem that may occur during storage and transportation, most BOPET manufacturers will focus on good sealing. Some manufacturers even put several layers of sealed packaging on the finished BOPET film to prevent the yellowing problem caused by gas fumigation during the storage of BOPET film.

[0006] The main problems with the above technical solutions are: (1) The above technical approach of using color powder to solve the yellowing problem in the BOPET film processing process requires a specific color matching scheme for each production process. This technical solution is not universal and has many disadvantages such as cumbersome process and imperfect yellowing removal effect in actual production operation. It is a technical solution that only treats the symptoms and not the root cause. (2) The above technical approach of using antioxidants to solve the thermo-oxidative aging problem in the BOPET film processing process often leads to a great deal of blindness in the selection of antioxidants in the industry. For example, many patents and documents mention the use of 1010 and 168 to solve the thermo-oxidative aging problem in the BOPET film processing process. However, this often does not have a good effect in actual production. For example, many companies mentioned above use antioxidants 1010 and 168 to prevent thermo-oxidative aging in the BOPET processing process. However, in actual production, they have not improved the yellowing problem much. The main reason is that antioxidant 1010 is prone to phenolic yellowing, while 168 has a very poor effect on color retention in actual application. (3) The problem of yellowing caused by gas fumes in BOPET film mentioned in the above technical ideas is not recognized by most companies in the industry. Therefore, most of them adopt solutions such as strengthening sealing and preservation, which are only temporary solutions.

[0007] Patent CN 109972411 A describes the preparation of nano-zinc oxide as an anti-yellowing agent using sodium hydroxide and zinc chloride as raw materials. This is combined with a compound of ester-based quaternary ammonium salt softener and N-dodecyl dimethylamine oxide, phosphite antioxidants, and UV absorber UV-531, and then extruded and granulated to produce an anti-yellowing masterbatch. This patent primarily utilizes the ultraviolet absorption function of nano-zinc oxide; additionally, the nanoparticles can scatter the ultraviolet light acting upon them in all directions, thereby reducing the intensity of ultraviolet light in the irradiated direction; the compound of ester-based quaternary ammonium salt softener and N-dodecyl dimethylamine oxide can improve the yellowing properties of fabrics. Patent CN 114276671A discloses a TPU anti-yellowing masterbatch, which includes the following raw materials: TPU, antioxidant, and ultraviolet absorber. The mass percentage of each raw material is: TPU 85-90%, antioxidant 3-5%, and ultraviolet absorber 7-10%. This TPU anti-yellowing masterbatch has excellent resistance to exudation, does not affect the performance of TPU, and the yellowing resistance level can reach 4.5 or higher.

[0008] While the aforementioned existing technologies can achieve a certain level of resistance to yellowing, they also have a narrow range of applications, only applicable to polyurethane materials, lacking versatility. Furthermore, they are only effective in resisting yellowing caused by ultraviolet radiation and thermo-oxidative aging, and their effect on yellowing caused by gas fumigation and yellowing of recycled materials during processing is not ideal. Summary of the Invention

[0009] To address the shortcomings and deficiencies of the existing technologies, the primary objective of this invention is to provide an anti-yellowing agent. This anti-yellowing agent employs specific hindered phenolic primary antioxidants and phosphite-based secondary antioxidants, combined with specific oleophilic nano-titanium dioxide powder, ultrafine hydrotalcite powder, and calcium stearate powder. It can simultaneously solve the problems of yellowing due to thermo-oxidative aging of polyester polymer materials such as BOPET film, yellowing during recycled material processing, and yellowing caused by gas fumigation during storage and transportation. It exhibits good anti-yellowing effect, strong versatility, economic cost, simple processing, stable performance, and convenient use, with broad application prospects.

[0010] Another object of the present invention is to provide a method for preparing the above-mentioned anti-yellowing agent.

[0011] Another object of the present invention is to provide the application of the above-mentioned anti-yellowing agent in polyester polymer materials such as BOPET film.

[0012] The objective of this invention is achieved through the following technical solution:

[0013] An anti-yellowing agent is composed of the following components in weight percentage: hindered phenolic primary antioxidant: 0.1%–30%, phosphite auxiliary antioxidant: 20%–90%, lipophilic nano-titanium dioxide powder: 0.1%–10%, ultrafine hydrotalcite powder: 0.1%–10%, and calcium stearate powder: 0.1%–5%.

[0014] Preferably, the anti-yellowing agent is composed of the following components in weight percentage: hindered phenolic primary antioxidant: 5%–10%, phosphite auxiliary antioxidant: 75%–80%, oleophilic nano-titanium dioxide powder: 5%–10%, ultrafine hydrotalcite powder: 2%–4%, and calcium stearate powder: 1%–3%.

[0015] Furthermore, the hindered phenolic primary antioxidant is one or two of antioxidant 1790 (Tianjin Lianlong Company, which will not be described again below) and antioxidant 3114 (Tianjin Lianlong Company, which will not be described again below).

[0016] Furthermore, the phosphite-based auxiliary antioxidant is one or more of antioxidants P-EPQ, PEP-36, and 9228.

[0017] Furthermore, the oleophilic nano-titanium dioxide powder is a self-made product, prepared by the following method:

[0018] Deionized water and anhydrous ethanol were added to nano-titanium dioxide powder and stirred until homogeneous to form a titanium dioxide slurry. Then, tetraethyl orthosilicate and acid were added sequentially to carry out a hydrolysis-condensation reaction. After the reaction was completed, the powder was washed and dried to obtain oleophilic nano-titanium dioxide powder.

[0019] Preferably, the nano-titanium dioxide powder is selected from titanium dioxide powder with a particle size of 20-100nm (such as the nano-titanium dioxide powder product with a particle size of 50nm produced by Ningbo Jiwei Nano New Materials Technology Co., Ltd.).

[0020] Preferably, the term "mixing evenly" refers to stirring at a constant speed of 400-800 rpm for 15-20 minutes.

[0021] Preferably, the amount of tetraethyl orthosilicate added is 5% to 20% of the mass of the nano-titanium dioxide powder.

[0022] Furthermore, the ultrafine hydrotalcite powder is AC-320 produced by Chenghe Technology.

[0023] Furthermore, the calcium stearate powder is ultrafine calcium stearate BS-3818 produced by Zhongshan Huamingtai Company.

[0024] The preparation method of the above-mentioned anti-yellowing agent includes the following preparation steps:

[0025] (1) Weigh the hindered phenolic main antioxidant and phosphite auxiliary antioxidant according to the ratio, put them in a 304 stainless steel bucket and mix them with a mixer for later use.

[0026] (2) Add oleophilic nano titanium dioxide powder, ultrafine hydrotalcite powder and calcium stearate powder to the mixture obtained in step (1) in sequence, and then stir thoroughly to obtain the anti-yellowing agent product.

[0027] Further, the stirring and mixing mentioned in step (1) refers to stirring at a speed of 400 to 600 rpm for 10 to 15 minutes.

[0028] Furthermore, the stirring mentioned in step (2) refers to stirring at a speed of 400-600 rpm for 15-20 minutes.

[0029] The above-mentioned anti-yellowing agent is used in polyester polymer materials, including PET, PC, PMMA, TPU or PBT.

[0030] The application of the above-mentioned anti-yellowing agent in BOPET film is as follows: the anti-yellowing agent is added to PET resin at a mass percentage of 0.01% to 0.5% and stirred evenly before being applied to BOPET film processing.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] (1) In the selection of antioxidants, we adopted a main antioxidant with good anti-fuming effect and large molecular weight, and an auxiliary antioxidant with high phosphorus content. This not only allows the color to be kept stable during the processing, but also gives the anti-yellowing agent product good anti-fuming performance.

[0033] (2) We use self-made oleophilic nano-titanium dioxide, which not only acts as a white pigment to cover some of the yellowing of the material, but also, the nano-titanium dioxide particles of a specific size can produce a Rayleigh scattering effect in polymer materials, giving the BOPET film a blue visual effect. This property is utilized to reduce the amount of nano-titanium dioxide used. The oleophilic treatment of the nano-titanium dioxide we use also enhances its dispersion in the PET substrate. In addition, nano-titanium dioxide itself is also an excellent light stabilizer, which can effectively prevent photoaging problems of BOPET film during use.

[0034] (3) The present invention introduces components such as hydrotalcite and calcium stearate into the formulation, which can enhance the dispersion of the anti-yellowing agent in polyester polymer materials such as PET and improve the anti-yellowing effect; it also has many advantages such as absorbing halogens and inhibiting the hydrolysis of polyester polymer materials such as PET.

[0035] (4) The anti-yellowing agent of this invention has a wide range of applications. It can be used not only in BOPET films but also in PET spinning, sheets, and other PET products. Furthermore, the anti-yellowing agent of this invention has excellent anti-yellowing effects on other polyester polymers such as PC, PMMA, TPU, and PBT in various molding processes including injection molding, extrusion, blow molding, and biaxial stretching. It also boasts numerous advantages such as simple addition, low cost, and excellent performance, making it a rare and valuable anti-yellowing agent. Attached Figure Description

[0036] Figures 1-2 The image shown is a SEM image of the anti-yellowing agent product obtained in Example 1.

[0037] Figure 3 A color comparison chart of a PET injection molding color swatch (left) of the product with 0.05% of the anti-yellowing agent from Example 1 and a PET injection molding color swatch (right) of the product without the anti-yellowing agent. Detailed Implementation

[0038] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0039] The oleophilic nano-titanium dioxide used in the following examples was prepared in-house using the following method:

[0040] Deionized water and anhydrous ethanol were added to nano-titanium dioxide powder (produced by Ningbo Jiwei Nano New Materials Technology Co., Ltd., with a particle size of 50nm). The mixture was stirred at a constant speed of 600rpm for 15min to prepare a titanium dioxide slurry. Then, 10% tetraethyl orthosilicate and an appropriate amount of hydrochloric acid were added sequentially to carry out a hydrolysis condensation reaction for 2h. After the reaction was completed, the solid product was washed with deionized water and ethanol sequentially and dried to obtain oleophilic nano-titanium dioxide powder.

[0041] Example 1

[0042] This embodiment describes an anti-yellowing agent product for use in BOPET film, comprising the following components by weight percentage:

[0043]

[0044] The anti-yellowing agent product is prepared by the following method:

[0045] (1) Weigh the hindered phenolic main antioxidant 1790 and the phosphite auxiliary antioxidant P-EPQ according to the ratio, put them in a 304 stainless steel bucket and mix them with a mixer for later use.

[0046] (2) Add oleophilic nano titanium dioxide powder, ultrafine hydrotalcite powder AC-320 and calcium stearate powder BS-3818 to the mixture obtained in step (1) in sequence, and then stir thoroughly to obtain the yellowing removal agent product.

[0047] The SEM image of the anti-yellowing agent product obtained in this embodiment is as follows: Figure 1 and Figure 2 As shown.

[0048] The anti-yellowing agent product prepared in this embodiment was added to PET resin (ordinary PET injection molding grade resin with 10% (wt.) of colorless and transparent recycled PET) at an addition amount of 0.05% (wt.%), and a 2mm color sample was injection molded. A 2mm color sample was also obtained by directly injection molding the same PET injection molding grade resin with 10% of colorless and transparent recycled PET. The color comparison results are as follows: Figure 3 As shown (the left image is the color chart of the product with added anti-yellowing agent, and the right image is the color chart of the product without added anti-yellowing agent).

[0049] Depend on Figure 3 The results show that, with the addition of a certain proportion of recycled PET, the anti-yellowing agent of the present invention exhibits excellent anti-yellowing effects.

[0050] Example 2

[0051] This embodiment describes an anti-yellowing agent product for use in BOPET film, comprising the following components by weight percentage:

[0052]

[0053]

[0054] The anti-yellowing agent product is prepared by the following method:

[0055] (1) Weigh the hindered phenolic primary antioxidant 1790 and phosphite auxiliary antioxidant 9228 according to the ratio, put them in a 304 stainless steel bucket and mix them with a mixer for later use.

[0056] (2) Add oleophilic nano titanium dioxide powder, ultrafine hydrotalcite powder AC-320 and calcium stearate powder BS-3818 to the mixture obtained in step (1) in sequence, and then stir thoroughly to obtain the yellowing removal agent product.

[0057] Example 3

[0058] This embodiment describes an anti-yellowing agent product for use in BOPET film, comprising the following components by weight percentage:

[0059]

[0060] The anti-yellowing agent product is prepared by the following method:

[0061] (1) Weigh the hindered phenolic main antioxidant 3114 and the phosphite auxiliary antioxidant PEP-36 according to the ratio, put them in a 304 stainless steel bucket and mix them with a mixer for later use.

[0062] (2) Add oleophilic nano titanium dioxide powder, ultrafine hydrotalcite powder AC-320 and calcium stearate powder BS-3818 to the mixture obtained in step (1) in sequence, and then stir thoroughly to obtain the yellowing removal agent product.

[0063] Example 4

[0064] This embodiment describes an anti-yellowing agent product for use in BOPET film, comprising the following components by weight percentage:

[0065]

[0066]

[0067] The anti-yellowing agent product is prepared by the following method:

[0068] (1) Weigh the hindered phenolic primary antioxidant 3114 and phosphite auxiliary antioxidant 9228 according to the ratio, put them in a 304 stainless steel bucket and mix them with a mixer for later use.

[0069] (2) Add oleophilic nano titanium dioxide powder, ultrafine hydrotalcite powder AC-320 and calcium stearate powder BS-3818 to the mixture obtained in step (1) in sequence, and then stir thoroughly to obtain the yellowing removal agent product.

[0070] The anti-yellowing agent product for BOPET film prepared in the above examples was added to PET resin (film-grade PET resin produced by Yizheng Chemical Fiber, model FG600) at an addition ratio of 0.05% (wt.%). After stirring evenly, a BOPET film with a thickness of 50 micrometers was prepared on a biaxial tensile testing machine, and the yellowing phenomenon of the BOPET film was observed.

[0071] To verify that the yellowing-reducing agent product described in this invention has excellent yellowing-reducing effect, two comparative BOPET products were set up.

[0072] Comparative Example 1

[0073] BOPET film products with a thickness of 50 micrometers are prepared directly on a biaxial tensile testing machine using pure PET resin (film-grade PET resin produced by Yizheng Chemical Fiber, model FG600) without adding any additives.

[0074] Comparative Example 2

[0075] 10% (wt.%) of PET transparent recycled material was added to the film-grade PET resin FG600 produced by Yizheng Chemical Fiber, and then a BOPET film product with a thickness of 50 micrometers was prepared on a biaxial tensile testing machine.

[0076] All BOPET film products produced in the examples (added to the BOPET film product of Comparative Example 2 at an addition amount of 0.05% (wt.%)) and the comparative example were observed and recorded when they were freshly produced. In addition, the film products were left exposed on the desk in the warehouse for one month to observe and record their color. The experimental results are shown in Table 1 below.

[0077] Table 1

[0078] project The color of the newly produced product The color of the product after being placed on the warehouse desk for a month Example 1 Colorless and transparent Colorless and transparent Example 2 Colorless and transparent Colorless and transparent Example 3 Colorless and transparent Colorless and transparent Example 4 Colorless and transparent Colorless and transparent Comparative Example 1 Colorless and transparent Slightly yellow Comparative Example 2 Yellowing Severe yellowing

[0079] The results above demonstrate that, with the addition of the anti-yellowing agent of this invention, BOPET film maintains its colorless and transparent properties effectively during processing, storage, and transportation. This indicates that the anti-yellowing agent of this invention can effectively address the yellowing caused by thermo-oxidative aging of polyester polymer materials such as BOPET film, yellowing during recycled material processing, and yellowing due to fumigation during storage and transportation.

[0080] Comparative Example 3

[0081] Compared with Example 1, the anti-yellowing agent product in this comparative example does not contain lipophilic nano-titanium dioxide and includes the following components by mass percentage:

[0082]

[0083] The preparation process of the anti-yellowing agent product is the same as that in Example 1.

[0084] Comparative Example 4

[0085] Compared with Example 1, the anti-yellowing agent product in this comparative example does not contain ultrafine hydrotalcite powder and calcium stearate powder, and includes the following components by mass percentage:

[0086] Hindered phenolic primary antioxidant 1790 10%;

[0087] Phosphite-based auxiliary antioxidant P-EPQ 80%;

[0088] 10% oleophilic nano-titanium dioxide;

[0089] The preparation process of the anti-yellowing agent product is the same as that in Example 1.

[0090] The anti-yellowing agents of Comparative Examples 3 and 4 were added to the BOPET film product of Comparative Example 2 at an addition amount of 0.05% (wt.%). The color of the film was observed and recorded immediately after production. In addition, the film product was left exposed on the desk in the warehouse for one month to observe and record the color. The experimental results are shown in Table 2 below.

[0091] Table 2

[0092] project The color of the newly produced product The color of the product after being placed on the warehouse desk for a month Comparative Example 3 Slightly yellow Slightly yellow Comparative Example 4 Slightly yellow Slightly yellow

[0093] As can be seen from the results in Table 2, the addition of oleophilic nano-titanium dioxide, ultrafine hydrotalcite powder, and calcium stearate powder to the anti-yellowing agent of this invention has a good synergistic effect on the anti-yellowing performance of BOPET film products containing recycled PET material.

[0094] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A yellowing-reducing agent, characterized in that, It is composed of the following components in the indicated mass percentages: hindered phenolic primary antioxidant: 0.1%~30%, phosphite secondary antioxidant: 20%~90%, lipophilic nano titanium dioxide powder: 0.1%~10%, ultrafine hydrotalcite powder: 0.1%~10%, and calcium stearate powder: 0.1%~5%. The oleophilic nano-titanium dioxide powder was prepared by the following method: Deionized water and anhydrous ethanol were added to nano-titanium dioxide powder and stirred until homogeneous to form a titanium dioxide slurry. Then, tetraethyl orthosilicate and acid were added sequentially to carry out a hydrolysis and condensation reaction. After the reaction was completed, the powder was washed and dried to obtain oleophilic nano-titanium dioxide powder. The ultrafine hydrotalcite powder is AC-320 produced by Chenghe Technology Co., Ltd.; the calcium stearate powder is ultrafine calcium stearate BS-3818 produced by Zhongshan Huamingtai Technology Co., Ltd.

2. The anti-yellowing agent according to claim 1, characterized in that, The yellowing-reducing agent is composed of the following components in mass percentage: hindered phenolic primary antioxidant: 5%~10%, phosphite auxiliary antioxidant: 75%~80%, lipophilic nano titanium dioxide powder: 5%~10%, ultrafine hydrotalcite powder: 2%~4%, and calcium stearate powder: 1%~3%.

3. The anti-yellowing agent according to claim 1 or 2, characterized in that, The hindered phenolic primary antioxidant is one or two of antioxidant 1790 and antioxidant 3114; the phosphite secondary antioxidant is one or more of antioxidant P-EPQ, antioxidant PEP-36, and antioxidant 9228.

4. The anti-yellowing agent according to claim 1, characterized in that, The nano-titanium dioxide powder is selected from titanium dioxide powder with a particle size of 20~100nm; the uniform mixing means stirring at a speed of 400~800rpm for 15~20min; the amount of tetraethyl orthosilicate added is 5%~20% of the mass of the nano-titanium dioxide powder.

5. A method for preparing an anti-yellowing agent according to any one of claims 1 to 4, characterized in that, The preparation steps include the following: (1) Weigh the hindered phenolic main antioxidant and phosphite auxiliary antioxidant according to the ratio, put them in a 304 stainless steel bucket and mix them with a mixer for later use. (2) Add oleophilic nano titanium dioxide powder, ultrafine hydrotalcite powder and calcium stearate powder to the mixture obtained in step (1) in sequence, and then stir thoroughly to obtain the anti-yellowing agent product.

6. The method for preparing an anti-yellowing agent according to claim 5, characterized in that, The stirring and mixing mentioned in step (1) refers to stirring at a speed of 400~600 rpm for 10~15 min; the stirring mentioned in step (2) refers to stirring at a speed of 400~600 rpm for 15~20 min.

7. The application of the anti-yellowing agent according to any one of claims 1 to 4 in polyester polymer materials, characterized in that, The polyester polymer materials include PET, PC, PMMA, TPU, or PBT.

8. The application of the anti-yellowing agent according to any one of claims 1 to 4 in BOPET film, characterized in that, The application process is as follows: the anti-yellowing agent is added to PET resin at a mass percentage of 0.01% to 0.5% and stirred evenly before being applied to BOPET film processing.

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