Polyhydroxyalkanoate- and balk-containing compostable polyester free of microplastic generation, preparation method therefor, and use thereof

Abstract

Disclosed are a polyhydroxyalkanoate- and BALK-containing compostable polyester free of microplastic generation, a preparation method therefor, and a use thereof. The polyester is a copolymer comprising a carboxyl-terminated polyester, an amorphous carbon dioxide-based polyester diol, and a polyhydroxyalkanoate diol as segments. The ratio of the carboxyl-terminated polyester to the amorphous carbon dioxide-based polyester diol to the polyhydroxyalkanoate diol is (10-30):(50-70):(5-20) in parts by mass. The preparation method for the polyester comprises: feeding raw materials into a reaction kettle, heating the raw materials to 175-200°C, adding a catalyst having an amount of 1‰-2% of the total mass of the raw materials, reacting the mixture for 0.5-5 h and then at 200-230°C for 3-4 h, then performing polycondensation under vacuum for 3-6 h, and cooling to obtain a polyester.

Description

A compostable, microplastic-free polyester containing polyhydroxyalkanoates and BALK, its preparation method and applications.

[0001] This disclosure claims priority to Chinese Patent Application No. 2024118632993, filed on December 17, 2024, entitled "A compostable polyester containing polyhydroxy fatty acid esters and BALK that does not produce microplastics, its preparation method and application", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure belongs to the field of pressure-sensitive adhesive technology. Specifically, this disclosure relates to compostable polyesters containing polyhydroxy fatty acid esters and BALK that do not produce microplastics, their preparation methods, and applications. Background Technology

[0003] Pressure-sensitive adhesives are resin elastomers that possess both the viscous properties of liquids and the elastic properties of solids. Using finger pressure, the adhesive can immediately bond to any smooth surface, and if the bonding surface is damaged, the adhesive will not contaminate it. In recent years, with the increasing demand for packaging, office supplies, and various labels, the demand for pressure-sensitive adhesives has also been growing.

[0004] With the widespread application of pressure-sensitive adhesives (PSAs) in packaging and other fields, the increasing amount of PSA waste has led to growing environmental pollution and resource waste, posing a significant challenge for the present and future. To address this issue, researchers must strengthen their research into renewable resources, seeking efficient and renewable biomass raw materials to replace non-renewable petroleum products. This is not only an inevitable trend in social development but also drives the development of biodegradable PSAs, becoming a crucial direction for the packaging and adhesives industry towards green and sustainable development.

[0005] Currently, pressure-sensitive adhesive (PSAs) substrates can be prepared using biodegradable materials, but PSAs still primarily utilize traditional non-degradable materials, mainly rubber-based, thermoplastic polyester resin elastomers, acrylate-based, silicone-based, and polyurethane-based materials. Rubber-based PSAs suffer from compatibility issues, leading to the easy precipitation of added additives and resulting in poor weather resistance and aging resistance. Acrylic copolymer PSAs typically contain unreacted acrylate monomers, have a strong odor, and can be irritating to humans. Polyurethane PSAs are less toxic than the previous two types, but they have poor degradability and tend to leave residue after peeling. In recent years, biodegradable PSAs have also received some research attention.

[0006] US Patent Application US20170283666A1 discloses a pressure-sensitive adhesive composition comprising a block copolymer, wherein the block copolymer comprises a first block having a glass transition temperature of 50°C or higher, and a second block having a glass transition temperature of -10°C or lower. The first block may be an alkyl methacrylate, and the second block may be an alkyl acrylate of an alkyl group having 1 to 4 carbon atoms. However, this pressure-sensitive adhesive composition uses acrylate substances, which have the problem of poor biodegradability.

[0007] Chinese patent application CN117447954A discloses a biodegradable hot melt pressure-sensitive adhesive, comprising the following components by weight: 65-85 parts biodegradable plastic, 5-25 parts biodegradable tackifying resin, 1-9 parts biodegradable plasticizer, 0-10 parts filler, and 1 part antioxidant. The biodegradable plastic is one or more of polybutylene succinate, polylactic acid, polyglycolic acid, polybutylene terephthalate, and polypropylene carbonate. The biodegradable tackifying resin is one or more of rosin, hydrogenated rosin, disproportionated rosin, esterified rosin, C5 petroleum resin, C9 petroleum resin, and terpene resin. However, this pressure-sensitive adhesive has poor adhesion and holding power, and its biodegradability needs improvement.

[0008] Chinese patent application CN118344570A discloses a biodegradable copolyester elastomer, specifically a copolymer of biodegradable hard segments and biodegradable soft segments. The hard segments are carboxyl-terminated polyesters, and the soft segments are non-crystalline carbon dioxide-based polyester diols. The hard segments have a mass ratio of 10-30% by mass and a number average molecular weight of 1100-3000, while the soft segments have a number average molecular weight of 2000-3000. Pressure-sensitive adhesives made from this elastomer exhibit excellent initial tack, holding power, and high peel strength, with a degradation rate of around 90%. However, with increasing environmental pressures, it is necessary to further improve the biodegradability of pressure-sensitive adhesives while simultaneously ensuring good pressure-sensitive properties. Summary of the Invention

[0009] According to various embodiments of this disclosure, a compostable polyester containing polyhydroxyalkanoates and BALK, a method for its preparation, a pressure-sensitive adhesive, and a pressure-sensitive adhesive product are provided. The applicant has discovered that copolymerizing polyhydroxyalkanoates to prepare polyhydroxyalkanoate diols via alcoholysis, and then copolymerizing these diols with carboxyl-terminated hard segments of polyester and non-crystalline carbon dioxide-based polyester diol soft segments, yields a polyester that retains excellent pressure-sensitive properties while significantly improving biodegradability. Furthermore, the polyester is found to be compostable and does not produce microplastics after degradation.

[0010] In a first aspect, this disclosure relates to a polyhydroxyalkanoate polyester, wherein the polyhydroxyalkanoate polyester is a copolymer comprising a carboxyl-terminated polyester, an amorphous carbon dioxide-based polyester diol, and a polyhydroxyalkanoate diol as chain segments, wherein the mass ratio of the carboxyl-terminated polyester, the amorphous carbon dioxide-based polyester diol, and the polyhydroxyalkanoate diol is (10~30):(50~70):(5~20), and the number average molecular weight of the polyhydroxyalkanoate polyester is 20,000~60,000.

[0011] Secondly, this disclosure relates to a method for preparing a polyhydroxyalkanoate polyester, comprising the following steps:

[0012] The carboxyl-terminated polyester, the amorphous carbon dioxide-based polyester diol, and the polyhydroxy fatty acid ester diol are added to a reaction vessel and heated to 175–200°C. A catalyst of 1‰–2% of the total mass of the carboxyl-terminated polyester, the amorphous carbon dioxide-based polyester diol, and the polyhydroxy fatty acid ester diol is added and reacted for 0.5–5 hours. Then, the reaction is carried out at 200–230°C for 3–4 hours, followed by vacuum polycondensation for 3–6 hours. After cooling, the polyhydroxy fatty acid ester polyester is obtained.

[0013] Thirdly, this disclosure also relates to the application of the aforementioned polyhydroxyalkanoate polyesters in adhesives, disposable products, flexible packaging, paper-plastic composites, fibers and nonwovens, foamed materials, or agricultural products. Specifically, the adhesives include pressure-sensitive adhesives; the disposable products include tableware, straws, or cups; the flexible packaging includes shopping bags, packaging films, and sealing films; the paper-plastic composites include paper bags and paper cups; the fibers and nonwovens include clothing, hygiene materials, and biomaterials; the foamed materials include cushioning and insulation materials; and the agricultural products include mulch films and coverings.

[0014] Fourthly, this disclosure also relates to a pressure-sensitive adhesive comprising the following components in parts by weight: 20 to 99 parts of the aforementioned polyhydroxyalkanoate polyester, 20 to 60 parts of tackifying resin, and 0.1 to 10 parts of additives.

[0015] Fifthly, this disclosure also relates to a pressure-sensitive adhesive product, including a substrate and a pressure-sensitive adhesive layer attached to the substrate, wherein the pressure-sensitive adhesive layer includes the pressure-sensitive adhesive, and the pressure-sensitive adhesive product is a pressure-sensitive adhesive tape, a pressure-sensitive adhesive stick, a label, or a sticker.

[0016] Details of one or more embodiments of this disclosure are set forth in the following description. Other features, objects, and advantages of this disclosure will become apparent from the specification and claims. The polyhydroxyalkanoate polyester exhibits excellent pressure-sensitive properties and biodegradability. Pressure-sensitive adhesives prepared from it possess pressure-sensitive properties, including an initial tack ball number of 7 or higher, a 180° peel strength of 6 N / 25 mm or higher, a holding power of 48 h or higher, and a degradation rate of 92% or higher. These properties are similar to those of existing BALK biodegradable pressure-sensitive adhesives, but with superior biodegradability. The polyester is compostable and does not produce microplastics after degradation. Embodiments of the present invention

[0017] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments.

[0018] Regarding the first aspect of this disclosure, the applicant, in order to further improve the biodegradability of pressure-sensitive adhesives, is considering introducing polyhydroxyalkanoates (PHA). Polyhydroxyalkanoates (PHA) are excellent biodegradable materials, capable of biodegradation under both aerobic and anaerobic conditions. Traditionally, the introduction of PHA is usually achieved through blending, such as blending PHA with PLA, PCL, PBS, PPC, or PBAT, to improve the material's toughness, elongation, etc. However, existing PHA utilization methods have a prominent problem: PHA has poor compatibility with other materials, easily leading to phase separation. In the field of pressure-sensitive adhesives, phase separation is a fatal flaw, causing severe deterioration of the adhesive's adhesion and peel strength, rendering it unusable. Therefore, introducing PHA into pressure-sensitive adhesives is extremely difficult. However, through research and development, the applicant unexpectedly discovered that by preparing polyhydroxyalkanoate diol through alcoholysis, and using it as a chain segment to copolymerize with BALK raw materials, the biodegradability of the pressure-sensitive adhesive can be significantly improved. At the same time, it does not have a negative effect on the pressure-sensitive performance of the pressure-sensitive adhesive, thus completing this disclosure.

[0019] In one preferred embodiment, the polyhydroxyalkanoate diol is obtained by alcoholysis of polyhydroxyalkanoate and diol. The applicant has discovered that adding a certain amount of polyhydroxyalkanoate diol segments to polyhydroxyalkanoate polyesters allows the polyhydroxyalkanoate to undergo hydrolysis of the CO bonds and further degradation in the natural environment, thus improving the degradability of polyhydroxyalkanoate polyesters. This results in good biodegradability in seawater, freshwater, soil, and sludge, while maintaining the same pressure-sensitive properties. To ensure the polyhydroxyalkanoate diol functions effectively, a mass fraction of 5 or more is required; otherwise, there is no significant change in degradability. To avoid adding too much and affecting the pressure sensitivity of the polyhydroxyalkanoate polyester, and considering overall cost, the mass fraction of the polyhydroxyalkanoate diol should be below 20. In one preferred embodiment, the mass fraction of the polyhydroxyalkanoate diol is preferably 6-18, more preferably 7-17, and also 8, 9, 10, 11, 12, 13, 14, 15, or 16.

[0020] In one preferred embodiment, the polyhydroxyalkanoate includes one or more of PHB, PHBV, P34HB, and PHBH, and the number average molecular weight of the polyhydroxyalkanoate is 30,000 to 200,000, preferably 40,000 to 150,000, specifically 45,000, 50,000, 55,000, 60,000, 65,000, 70,000, 75,000, 80,000, 85,000, 90,000, 95,000, 100,000, 110,000, 120,000, 130,000, and 140,000.

[0021] The number-average molecular weight of polyhydroxyalkanoate diols needs to be controlled within a suitable range. The preferred number-average molecular weight is 1,000–3,000, more preferably 1,200–2,500, and can also be 1,300, 1,400, 1,500, 1,600, 1,700, 1,800, 1,900, 2,000, 2,100, 2,200, 2,300, or 2,400. Only polyhydroxyalkanoate diols with suitable molecular weights can provide the number of hydroxyl groups required for polymerization, ensuring that the pressure-sensitive properties required by polyhydroxyalkanoate polyesters remain unchanged.

[0022] In one preferred embodiment, the number-average molecular weight of the carboxyl-terminated polyester can be 1,100 to 3,000. Since the number-average molecular weight of each segment affects the performance of polyhydroxyalkanoate polyesters, for the carboxyl-terminated polyester, the higher the number-average molecular weight, the stronger the crystallinity and the stronger the ability to act as a physical crosslinking point. In order to obtain better performance, the number-average molecular weight of the carboxyl-terminated polyester can be above 1,100. However, excessively high number-average molecular weight leads to stronger crystallinity, which increases the degree of microphase separation in the polyhydroxyalkanoate polyester pressure-sensitive adhesive, resulting in a decrease in the performance of the polyhydroxyalkanoate polyester pressure-sensitive adhesive. The number-average molecular weight of the carboxyl-terminated polyester can be below 3,000. Specifically, the number-average molecular weight of the carboxyl-terminated polyester can be 1,200, 1,400, 1,600, 1,800, 2,000, 2,200, 2,400, 2,600, 2,800 or 2,900.

[0023] In one preferred embodiment, the carboxyl-terminated polyester comprises 10 to 30 parts by weight. Because the carboxyl-terminated polyester contains carboxyl groups, it can act as a physical crosslinking point to form polyhydroxyalkanoate polyesters with carbon dioxide-based polyester diols, thereby improving the overall cohesive strength of the resin and satisfying the adhesive properties of the pressure-sensitive adhesive, enabling the application of polyhydroxyalkanoate polyesters in the pressure-sensitive adhesive field. To ensure its effectiveness, the carboxyl-terminated polyester can comprise more than 10 parts by weight. While increasing its content increases the cohesive properties of the polyhydroxyalkanoate polyester, excessively high carboxyl-terminated polyester content leads to increased phase separation, resulting in decreased polyhydroxyalkanoate polyester performance and consequently, decreased pressure-sensitive adhesive performance. Furthermore, excessively high carboxyl-terminated polyester content also increases the physical entanglement of the polyhydroxyalkanoate polyester, leading to a decreased degradation rate. Therefore, the carboxyl-terminated polyester is controlled to comprise less than 30 parts by weight. Specifically, the mass fraction of the carboxyl-terminated polyester can be 12, 14, 16, 18, 20, 22, 24, 26 or 28.

[0024] In one preferred embodiment, the carboxyl-terminated polyester is polymerized from a C3-7 dicarboxylic acid and a C3-7 diol.

[0025] In one preferred embodiment, the carboxyl-terminated polyester is preferably polybutylene succinate (PBS). PBS is a novel biodegradable polymer material. Its degradation mechanism involves first hydrolysis of CO bonds, followed by further degradation under enzymatic action. PBS is a crystalline substance that can act as a physical crosslinking point to form polyhydroxyalkanoate polyesters with polycarbonate and polyhydroxyalkanoate diols, thereby improving the overall cohesive strength of the resin. This allows it to be used in pressure-sensitive adhesives, meeting the higher adhesion requirements of these adhesives. Furthermore, PBS is synthesized from biomass, a second type of carbon source, and exhibits good degradation performance.

[0026] In one preferred embodiment, the carboxyl-terminated polybutylene succinate has a hydroxyl value of 37.4–112 mgKOH / g and a number-average molecular weight of 1,000–3,000.

[0027] In one preferred embodiment, the number-average molecular weight of the amorphous carbon dioxide-based polyester diol is 2,000 to 4,000. For the amorphous carbon dioxide-based polyester diol segments, if the number-average molecular weight is too low, the segments are too short, and the elasticity of the polyhydroxyalkanoate polyester will decrease. Therefore, its number-average molecular weight is preferably above 2,000. Conversely, if the number-average molecular weight is too high, it corresponds to a decrease in the content of the carboxyl-terminated polyester, resulting in a decrease in the strength of the polyhydroxyalkanoate polyester. The number-average molecular weight is preferably controlled to be below 3,000. Specifically, the number-average molecular weight of the amorphous carbon dioxide-based polyester diol segments can be 2,200, 2,400, 2,600, 2,800, 3,000, 3,200, 3,400, 3,600, or 3,800.

[0028] In one preferred embodiment, the amorphous carbon dioxide-based polyester diol is preferably polypropylene carbonate diol (PPC), with a number-average molecular weight preferably between 2,000 and 4,000. PPC is also a novel biodegradable polymer material, being a CO2-based diol derived from a third type of carbon source, exhibiting rapid degradation and a high degradation rate.

[0029] In one preferred embodiment, the hydroxyl value of the non-crystalline carbon dioxide-based polyester diol is 28.05~56.1 mgKOH / g.

[0030] In one preferred embodiment, the polyhydroxyalkanoate polyester has a number-average molecular weight of 25,000 to 60,000, preferably 26,000 to 40,000, and more preferably 28,000 to 38,000. For polyhydroxyalkanoate polyesters, the number average molecular weight is preferably above 20,000 to obtain better cohesion. If the number average molecular weight is too high, its degradation performance will decrease. Therefore, the number average molecular weight is preferably below 60,000. The number average molecular weight of polyhydroxyalkanoate polyesters can be 30,000, 32,000, 34,000, 36,000, 38,000, 40,000, 42,000, 44,000, 46,000, 48,000, 50,000, 52,000, 54,000, 56,000 or 58,000.

[0031] The above-mentioned polyhydroxy fatty acid ester diol, carboxyl-terminated polyester, and non-crystalline carbon dioxide-based polyester diol were reacted in a certain proportion to obtain polyhydroxy fatty acid ester polyester. This polyhydroxy fatty acid ester polyester contains carboxyl-terminated polyester segments, carbon dioxide-based polyester segments, and polyhydroxy fatty acid ester diol segments. Since both carboxyl-terminated polyester and non-crystalline carbon dioxide-based polyester diol are novel biodegradable polymers, and the introduction of polyhydroxy fatty acid ester groups significantly improves the biodegradability of the polyhydroxy fatty acid ester polyester, it also unexpectedly maintains excellent pressure-sensitive properties.

[0032] In one preferred embodiment, the sum of the mass parts of the carboxyl-terminated polyester, the amorphous carbon dioxide-based polyester diol, and the polyhydroxyalkanoate diol is 100.

[0033] Regarding the second aspect of this disclosure, in a preferred embodiment of the method for preparing polyhydroxyalkanoate polyesters, a carboxyl-terminated polyester, an amorphous carbon dioxide-based polyester diol, and the polyhydroxyalkanoate diol are added to a reaction vessel. After heating to 180–200°C, a catalyst of 1 wt%–5 wt% of the total mass of the carboxyl-terminated polyester, the amorphous carbon dioxide-based polyester diol, and the polyhydroxyalkanoate diol is added. The reaction is carried out for 2–3 hours, followed by a reaction at 210–230°C for 2–4 hours. After vacuum polycondensation for 3–6 hours, the mixture is cooled to room temperature to obtain a polyhydroxyalkanoate polyester, wherein the vacuum degree is within 0.5 mmHg.

[0034] In one preferred embodiment, the preparation of the polyhydroxy fatty acid ester diol includes the following steps:

[0035] Polyhydroxy fatty acid esters are added to an organic solvent, along with a diol and a catalyst of 1 wt% to 2 wt% by total mass. The mixture is reacted at 30–60 °C for 1–50 h, cooled to room temperature, and then concentrated and separated to obtain the polyhydroxy fatty acid ester diol. The molar ratio of polyhydroxy fatty acid ester to diol is 1:(1–20).

[0036] In one preferred embodiment, a polyhydroxy fatty acid ester is added to an organic solvent, along with a diol and a catalyst of 1 wt‰ to 8 wt‰ of total mass. The mixture is reacted at 40 to 50°C for 2 to 10 hours, cooled to room temperature, and then concentrated and separated to obtain the polyhydroxy fatty acid ester diol. The molar ratio of the polyhydroxy fatty acid ester to the diol is 1:(1 to 15), preferably 1:(3 to 10), and more preferably 1:5.

[0037] In one preferred embodiment, the diol includes one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, diethanolamine, 2-amino-2-methyl-1,3-propylene glycol, 2-amino-1,3-propylene glycol, 3-amino-1,2-propylene glycol, and bisphenol A.

[0038] In one preferred embodiment, the organic solvent is chloroform or dichloroethane, wherein the mass-to-volume ratio of the polyhydroxyalkanoate to the organic solvent is 1:(5~20), preferably 1:(7~15), and more preferably 1:10.

[0039] In one preferred embodiment, the catalyst is tetrabutyl titanate, tetraisopropyl titanate, or p-toluenesulfonic acid.

[0040] In one preferred embodiment, the polyhydroxyalkanoate is purified before being added to the organic solvent. The specific purification method is as follows: the polyhydroxyalkanoate is dissolved in chloroform, stirred until completely dissolved, filtered under reduced pressure, and then the filtrate is concentrated. The concentrated liquid is poured into ice-cold methanol and stirred until precipitation occurs, followed by filtration and drying.

[0041] In one preferred embodiment, the purification method specifically involves dissolving polyhydroxy fatty acid ester in chloroform at a mass-to-volume ratio of 1:10, stirring until completely dissolved, filtering under reduced pressure, transferring the filtrate to a rotary evaporator, concentrating the filtrate by rotary evaporation, pouring the concentrated liquid into ice-cold methanol at 0°C and stirring until precipitation occurs, filtering under reduced pressure to obtain a yellow flocculent substance, and drying under reduced pressure at 40°C to constant weight.

[0042] Regarding the polyhydroxyalkanoate polyester pressure-sensitive adhesive described in the third aspect of this disclosure, in one preferred embodiment, the polyhydroxyalkanoate polyester is preferably 45-80 parts, more preferably 50-60 parts.

[0043] In one preferred embodiment, the tackifying resin is preferably 30-60 parts, more preferably 40-50 parts, and the tackifying resin is one or more of natural rosin, hydrogenated rosin, disproportionated rosin, esterified rosin, C5 petroleum resin, C9 petroleum resin, and terpene resin.

[0044] In one preferred embodiment, the additives include plasticizers, antioxidants, fillers, pigments, rheology modifiers, light stabilizers, ultraviolet absorbers, and other auxiliaries such as desiccants, flow agents and flow control agents, surfactants, or catalysts.

[0045] In one preferred embodiment, the plasticizer is preferably 1 to 10 parts, and the antioxidant is preferably 0.1 to 0.2 parts.

[0046] The plasticizer is one or more of epoxidized soybean oil, flaxseed oil, castor oil, and palm oil.

[0047] In one preferred embodiment, the antioxidant is one or more of tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, di(tridecyl)thiodipropionate, and pentaerythritol tetrakis{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate}.

[0048] Regarding the fourth aspect of this disclosure, in one preferred embodiment, the substrate is selected from white paper, textiles, nonwoven fabrics, polymers, metals, or wood, and the substrate is preferably one of cellulose film, PET film, or paper; and / or, the thickness of the pressure-sensitive adhesive layer is 10–30 μm.

[0049] In one preferred embodiment, the pressure-sensitive adhesive product is an adhesive tape, adhesive stick, or film roll.

[0050] In one preferred embodiment, the pressure-sensitive adhesive product has an initial tack ball number of 7 or higher, and / or a 180° peel strength of 6 N / 25 mm or higher, and / or a holding power of 48 h or higher, and / or a degradation rate of 92% or higher, preferably 93% or higher, more preferably 94% or higher, and most preferably 95% or higher.

[0051] Example

[0052] The embodiments disclosed herein are for illustrative purposes only and should not be construed as limiting the scope of this disclosure.

[0053] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range, just as any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can serve as its own lower or upper limit and be combined with any other point or individual value, or with other lower or upper limits, to form an undefined range.

[0054] The foregoing description of this application is not intended to describe every disclosed implementation or method. Instead, the following description provides more specific examples of exemplary embodiments. Throughout the application, guidance is provided through a series of embodiments that can be used in various combinations. The examples listed are representative only and should not be construed as exhaustive.

[0055] Unless otherwise specified, the raw materials used in the following examples are all commercially available products. PHB and P34HB were purchased from Blue Crystal Microorganisms. The number average molecular weight of PHB is 50,000 and the number average molecular weight of P34HB is 80,000.

[0056] The preparation process of polyhydroxy fatty acid ester diol 1 described in the following examples is as follows:

[0057] Polyhydroxyalkanoate diol 1 is PHB diol. PHB is dissolved in chloroform at a mass-to-volume ratio of 1:10 and stirred until completely dissolved. The solution is filtered under reduced pressure, and the filtrate is transferred to a rotary evaporator. The filtrate is concentrated by rotary evaporation, and the concentrated liquid is poured into ice-cold methanol at 0°C and stirred until precipitation occurs. After vacuum filtration, a yellow flocculent substance is obtained. After drying under reduced pressure at 40°C to constant weight, the purified PHB is obtained.

[0058] PHB and chloroform were added to a flask at a mass ratio of 1:10. A condenser and liquid seal were installed, and the flask was heated to 45°C in a magnetic stirrer. The mixture was stirred until fully dissolved, and then esterification was carried out by adding 5 times the molar amount of PHB diol and 2 wt‰ of catalyst. The reaction was carried out for 3 hours. After the reaction was completed, the system was allowed to cool naturally to room temperature. The solution was then poured into a separatory funnel, washed three times with water, and filtered under reduced pressure to obtain a yellow liquid. The concentrated liquid was obtained by rotary evaporation. The concentrated liquid was added to ice-cold methanol at 0°C and stirred until precipitation occurred. The powder was then filtered under reduced pressure to obtain a yellow powder, which was dried under vacuum at 40°C to constant weight to obtain PHB diol with a number average molecular weight of 1600.

[0059] The preparation process of polyhydroxy fatty acid ester diol 2 described in the following examples is as follows:

[0060] Polyhydroxyalkanoate diol 2 is PHB diol. PHB is dissolved in chloroform at a mass-to-volume ratio of 1:10 and stirred until completely dissolved. The mixture is then filtered under reduced pressure, and the filtrate is transferred to a rotary evaporator. The filtrate is concentrated by rotary evaporation, and the concentrated liquid is poured into ice-cold methanol at 0°C and stirred until precipitation occurs. After vacuum filtration, a yellow flocculent substance is obtained. The purified PHB is then obtained by drying under reduced pressure at 40°C to constant weight.

[0061] PHB and chloroform were added to a flask at a mass ratio of 1:10. A condenser and liquid seal were installed, and the flask was heated to 50°C in a magnetic stirrer. The mixture was stirred until fully dissolved, and then esterification was carried out by adding 6 times the molar amount of PHB diol and 1.5 wt‰ of catalyst. The reaction was carried out for 2 hours. After the reaction was completed, the system was allowed to cool naturally to room temperature. The solution was then poured into a separatory funnel, washed three times with water, and filtered under reduced pressure to obtain a yellow liquid. The concentrated liquid was obtained by rotary evaporation. The concentrated liquid was added to ice-cold methanol at 0°C and stirred until precipitation occurred. After filtration under reduced pressure, a yellow powder was obtained. The powder was dried under vacuum at 40°C to constant weight to obtain PHB diol with a number average molecular weight of 2000.

[0062] The preparation process of polyhydroxy fatty acid ester diol 3 described in the following examples is as follows:

[0063] The polyhydroxyalkanoate diol 3 is P34HB diol. P34HB is dissolved in chloroform at a mass-to-volume ratio of 1:10 and stirred until completely dissolved. The mixture is then filtered under reduced pressure, and the filtrate is transferred to a rotary evaporator. The filtrate is concentrated by rotary evaporation, and the concentrated liquid is poured into ice-cold methanol at 0°C and stirred until precipitation occurs. After vacuum filtration, a yellow flocculent substance is obtained. The purified P34HB is then obtained by drying under reduced pressure at 40°C to constant weight.

[0064] P34HB and chloroform were added to a flask at a mass ratio of 1:10. A condenser and liquid seal were installed, and the flask was heated to 55°C in a magnetic stirrer. The mixture was stirred until fully dissolved, and then 5.5 times the molar amount of P34HB diol and 2 wt‰ of catalyst were added to initiate an esterification reaction. The reaction was carried out for 3 hours. After the reaction was completed, the system was allowed to cool naturally to room temperature. The solution was then poured into a separatory funnel, washed three times with water, and filtered under reduced pressure to obtain a yellow liquid. The concentrated liquid was obtained by rotary evaporation. The concentrated liquid was added to ice-cold methanol at 0°C and stirred until precipitation occurred. After filtration under reduced pressure, a yellow powder was obtained. The powder was dried under vacuum at 40°C to constant weight to obtain P34HB diol with a number average molecular weight of 1800.

[0065] The preparation process of polyhydroxy fatty acid ester diol 4 described in the following examples is as follows:

[0066] The polyhydroxyalkanoate diol 4 is PHB diol. PHB and chloroform were added to a flask at a mass ratio of 1:10. A condenser and liquid seal device were installed, and the flask was heated to 50°C in a magnetic stirrer. The mixture was stirred until fully dissolved, and then esterification was carried out by adding 5 times the molar amount of PHB diol and 2.5 wt‰ of catalyst. The reaction was carried out for 3.5 hours. After the reaction was completed, the system was allowed to cool naturally to room temperature. The solution was then poured into a separatory funnel, washed three times with water, and filtered under reduced pressure to obtain a yellow liquid. After rotary evaporation, a concentrated liquid was obtained. The concentrated liquid was added to ice-cold methanol at 0°C and stirred until precipitation. After filtration under reduced pressure, a yellow powder was obtained. The powder was dried under vacuum at 45°C to constant weight to obtain PHB diol with a number average molecular weight of 1500.

[0067] The preparation process of carboxyl-terminated polybutylene succinate (PBS) described in the following examples is as follows:

[0068] Forty parts of 1,4-butanediol and 60 parts of succinic acid were added to a reaction vessel, and the temperature was raised to 165°C. Tetrabutyl titanate, a catalyst, was added at a total mass of 0.3 wt% of the combined 1,4-butanediol and succinic acid, and the reaction proceeded for approximately 3 hours. The temperature was then raised to 180°C and reacted for approximately 1 hour. Finally, the temperature was raised to 205°C and vacuum polycondensed for 2.5 hours. After cooling to room temperature, carboxyl-terminated polybutylene succinate was obtained, and its acid value was tested. The tested acid value was 70.125 mg KOH / g (the calculated number-average molecular weight was 1600, calculated using the formula: Mn = (56.1 × 2000) / y, where y is the acid value).

[0069] The method for determining the acid value is as follows: Dissolve an appropriate amount of sample thoroughly in 25 mL of chloroform solution, use phenolphthalein as an indicator, and titrate with 0.1 mol / L potassium hydroxide / ethanol standard solution until the solution turns red and remains so for 30 seconds. The acid value X of the sample is calculated according to formula (1):

[0070] X=56.1×((V_2—V_1)×C) / m (1)

[0071] Where 56.1 is the molar mass of potassium hydroxide (g / mol); X represents the acid value of the sample (mgKOH / g); V1 is the volume (mL) of potassium hydroxide ethanol standard solution before titration; V2 is the volume (mL) of potassium hydroxide ethanol standard solution after titration; C is the concentration (mol / L) of potassium hydroxide ethanol standard solution; and m is the weight (g) of the sample being titrated.

[0072] The polypropylene carbonate diols described in the following examples were all purchased from Huizhou Daya Bay Dazhi Fine Chemical Co., Ltd., with a number average molecular weight of approximately 2500 and a hydroxyl value of approximately 44.88 mgKOH / g.

[0073] The method for determining the number-average molecular weight in the following examples is as follows:

[0074] GPC test method: The test was conducted using a Waters 1515 GPC instrument from the United States, with tetrahydrofuran (THF) as the mobile phase and a flow rate of 0.1 mL / min. Monodisperse polystyrene was used as the number-average molecular weight correction standard.

[0075] Example 1

[0076] A polyhydroxyalkanoate polyester, the preparation process of which is as follows:

[0077] Carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 1 were added to a reaction vessel in a mass ratio of 10:82:8. The temperature was then raised to 180°C, and 0.2 wt% of tetrabutyl titanate catalyst (the total mass of the carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 1) was added. The reaction was carried out for 2 hours, followed by a further increase in temperature to 220°C and a reaction for 3 hours. Then, vacuum polycondensation was performed for 4 hours, and the mixture was cooled to room temperature to obtain a polyhydroxyalkanoate polyester. The number average molecular weight was determined to be approximately 36,000 by GPC.

[0078] Example 2

[0079] A polyhydroxyalkanoate polyester, the preparation process of which is as follows:

[0080] Carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 1 were added to a reaction vessel in a mass ratio of 10:80:10. The temperature was then raised to 185°C, and 0.25 wt% of tetrabutyl titanate catalyst (the total mass of the carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 1) was added. The reaction was carried out for 2 hours, followed by a further increase in temperature to 215°C and a reaction for 3 hours. Then, vacuum polycondensation was performed for 4.5 hours, and the mixture was cooled to room temperature to obtain a polyhydroxyalkanoate polyester. The number average molecular weight was determined to be approximately 38,000 by GPC.

[0081] Example 3

[0082] A polyhydroxyalkanoate polyester, the preparation process of which is as follows:

[0083] Carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 1 were added to a reaction vessel in a mass ratio of 15:77:8. The temperature was then raised to 175°C, and 0.3 wt% of tetrabutyl titanate catalyst (the total mass of the carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 1) was added. The reaction was carried out for 2 hours, and then the temperature was raised to 225°C for 3 hours. Subsequently, vacuum polycondensation was performed for 3.5 hours, and the mixture was cooled to room temperature to obtain a polyhydroxyalkanoate polyester. The number average molecular weight was determined to be approximately 33,000 by GPC.

[0084] Example 4

[0085] A polyhydroxyalkanoate polyester, the preparation process of which is as follows:

[0086] Carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 1 were added to a reaction vessel in a mass ratio of 12:73:15. The temperature was then raised to 180°C, and 0.2 wt% of tetrabutyl titanate catalyst (the total mass of the carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 1) was added. The reaction was carried out for 2 hours, and then the temperature was raised to 220°C for 3 hours. Subsequently, vacuum polycondensation was performed for 5 hours, and the mixture was cooled to room temperature to obtain a polyhydroxyalkanoate polyester. The number average molecular weight was determined to be approximately 40,000 by GPC.

[0087] Example 5

[0088] A polyhydroxyalkanoate polyester, the preparation process of which is as follows:

[0089] Carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 2 were added to a reaction vessel in a mass ratio of 10:82:8. The temperature was then raised to 185°C, and 0.25 wt% of tetrabutyl titanate catalyst was added to the mixture. The reaction was carried out for 2.5 h, followed by a further heating to 230°C and a reaction for 3 h. The mixture was then subjected to vacuum polycondensation for 4 h and cooled to room temperature to obtain a polyhydroxyalkanoate polyester. The number average molecular weight was determined to be approximately 35,000 by GPC.

[0090] Example 6

[0091] A polyhydroxyalkanoate polyester, the preparation process of which is as follows:

[0092] Carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 3 were added to a reaction vessel in a mass ratio of 10:82:8. The temperature was then raised to 180°C, and 0.3 wt% of tetrabutyl titanate catalyst was added to the total mass of the carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 3. The reaction was carried out for 2 hours, and then the temperature was raised to 215°C for 3 hours. Subsequently, vacuum polycondensation was carried out for 5 hours, and the mixture was cooled to room temperature to obtain a polyhydroxyalkanoate polyester. The number average molecular weight was determined to be approximately 39,000 by GPC.

[0093] Example 7

[0094] A polyhydroxyalkanoate polyester, the preparation process of which is as follows:

[0095] Carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 4 were added to a reaction vessel in a mass ratio of 10:82:8. The temperature was then raised to 185°C, and 0.3 wt% of tetrabutyl titanate catalyst (the total mass of the carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and polyhydroxyalkanoate diol 1) was added. The reaction was carried out for 2 hours, and then the temperature was raised to 230°C for 3 hours. Vacuum polycondensation was then carried out for 4 hours, and the mixture was cooled to room temperature to obtain a polyhydroxyalkanoate polyester. The number average molecular weight was determined to be approximately 36,000 by GPC.

[0096] Examples 8 to 14

[0097] The preparation process of polyhydroxy fatty acid ester-based polyester pressure-sensitive adhesive is as follows:

[0098] The polyhydroxyalkanoate polyesters described in Examples 1 to 7 were respectively formulated into polyhydroxyalkanoate polyester type pressure-sensitive adhesives 8 to 14, and the preparation methods are as follows:

[0099] 50 parts of polyhydroxy fatty acid ester polyester, 45 parts of tackifying resin, 5 parts of epoxidized soybean oil and 0.15 parts of antioxidant tris(2,4-di-tert-butylphenyl) phosphite were mixed and stirred at 120°C for 5 hours. After cooling to room temperature, ethyl acetate solution was added to obtain a pressure-sensitive adhesive solution with a solid content of 15 wt%.

[0100] The pressure-sensitive adhesive solution was coated onto a PET film using a coating machine and kept at 75°C for 15 minutes to obtain a polyhydroxy fatty acid ester polyester pressure-sensitive adhesive with a layer thickness of 30 μm.

[0101] Comparative Example 1

[0102] A pressure-sensitive adhesive, the preparation process of which is basically the same as that of Example 8, the difference being that a copolyester is used instead of a polyhydroxyalkanoate polyester. The copolyester preparation process of this comparative example is as follows:

[0103] Carboxyl-terminated polybutylene succinate and polypropylene carbonate diol were added to a reactor in a mass ratio of 18:82. The temperature was then raised to 180°C, and 0.2 wt% of tetrabutyl titanate catalyst was added to the mixture. The reaction was carried out for 2 hours, followed by a further increase in temperature to 220°C for 3 hours. The mixture was then subjected to vacuum polycondensation for 4 hours and cooled to room temperature to obtain a copolyester. The number average molecular weight was determined to be approximately 35,000 by GPC.

[0104] Comparative Example 2

[0105] A pressure-sensitive adhesive, the preparation process of which is basically the same as that of Example 8, except that the mass ratio of carboxyl-terminated polybutylene succinate, polypropylene carbonate diol, and the polyhydroxy fatty acid ester diol 1 is 10:62:28.

[0106] Comparative Example 3

[0107] A pressure-sensitive adhesive was prepared in a manner similar to that of Example 8, except that vacuum polycondensation was controlled for 8 hours, and the number-average molecular weight was approximately 66,000 as determined by GPC.

[0108] Comparative Example 4

[0109] A pressure-sensitive adhesive, whose preparation process is basically the same as that in Example 8, except that vacuum polycondensation is controlled for 2 hours, and the number-average molecular weight is approximately 20,000 as determined by GPC.

[0110] The performance of the polyhydroxyalkanoate polyester pressure-sensitive adhesives of Examples 8 to 14 and the pressure-sensitive adhesives of Comparative Examples 1 to 4 were tested. The test items and methods are as follows:

[0111] (1) Initial tack: Tested according to Method A in GB / T 4852-2002, with the inclined plane tilted at 30°.

[0112] (2) 180 peel strength: Tested according to the provisions of GB / T 2792.

[0113] (3) Holding power: The test shall be conducted in accordance with Method A of GB / T 4851-2014. The width of the biodegradable tape sample shall be 25 mm, the length of the bonding surface between the sample and the steel plate shall be (12±0.5 mm), and the mass of the weight shall be (1000±5 g).

[0114] (4) Biodegradation rate: Tested according to GB / T 19277.1.

[0115] (5) Aging resistance: The tape was placed in a constant temperature and humidity aging chamber at 70°C and 95% humidity for 72 hours, and then its peel strength was measured.

[0116] The test results are shown in Table 1.

[0117] Table 1

[0118] Initial Tack (Ball Size) 180° Peel Strength (N / 25mm) Holding Power (h) Biodegradation Rate (%) Peel Strength After Aging (N / 25mm) Example 8 108.6 >72 93% 6.7 Example 9 98 >72 94% 6.3 Example 10 99.2 >72 93% 6.2 Example 11 87.3 >72 95% 5.9 Example 12 98.5 >72 93% 6.0 Example 13 98.0 >72 93% 6.4 Example 14 87.6 >48, <72h 93% 6 Comparative Example 1 108.8 >72 90% 6.8 Comparative Example 2 54.6 <48 94% 2.7 Comparative Example 3 65.8 >48 83% 4.5 Comparative Example 4 85.4 <48 89% 2.9

[0119] As can be seen from the examples and comparative examples, compared with the polyester pressure-sensitive adhesive without the introduction of polyhydroxyalkanoate (Comparative Example 1), the polyester processed into pressure-sensitive adhesives of Examples 8-14 of this disclosure exhibit comparable pressure-sensitive performance (initial tack, 180° peel strength, holding power, and peel strength after aging), and the biodegradability rate is increased from 90% to over 93%, demonstrating better degradability and thus meeting higher requirements for degradability. In Comparative Example 2, the polyhydroxyalkanoate diol content exceeded the requirements, and the polyester molecular weights of Comparative Examples 3 and 4 were too high and too low, respectively. It can be seen that the final pressure-sensitive adhesive has poor pressure-sensitive performance and cannot meet the requirements for use. The degradability of Comparative Example 3 is also reduced. Experiments revealed that the pressure-sensitive adhesives of Examples 8-14 are compostable, and after degradation, no microplastics were produced.

[0120] Obviously, the above embodiments of this disclosure are merely examples for clearly illustrating the technical solutions of this disclosure, and are not intended to limit the specific implementation of this disclosure. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the claims of this disclosure should be included within the protection scope of the claims of this disclosure.

Claims

1. A polyhydroxyalkanoate polyester, characterized in that, The polyhydroxyalkanoate polyester is a copolymer comprising carboxyl-terminated polyester, non-crystalline carbon dioxide-based polyester diol, and polyhydroxyalkanoate diol as chain segments. The mass ratio of the carboxyl-terminated polyester, the non-crystalline carbon dioxide-based polyester diol, and the polyhydroxyalkanoate diol is (10~30):(50~70):(5~20), and the number average molecular weight of the polyhydroxyalkanoate polyester is 25,000~60,000.

2. The polyhydroxyalkanoate polyester resin according to claim 1, characterized in that, The polyhydroxy fatty acid ester diol has a mass fraction of 6 to 15 parts.

3. The polyhydroxyalkanoate polyester according to claim 1, characterized in that, The polyhydroxy fatty acid ester diol is obtained by alcoholysis of polyhydroxy fatty acid ester and diol, and the number-average molecular weight of the polyhydroxy fatty acid ester diol is 1000~3000. The polyhydroxy fatty acid ester includes one or more of PHB, PHBV, P34HB, and PHBH.

4. The polyhydroxyalkanoate polyester according to claim 1, characterized in that, The number-average molecular weight of the carboxyl-terminated polyester is 1100 to 3000, and / or the carboxyl-terminated polyester is polymerized from C3-7 dicarboxylic acid and C3-7 diol, and / or the number-average molecular weight of the amorphous carbon dioxide-based polyester diol is 2000 to 4000.

5. The polyhydroxyalkanoate polyester according to claim 4, characterized in that, The carboxyl-terminated polyester is carboxyl-terminated polybutylene succinate with a hydroxyl value of 37.4–112 mgKOH / g, and / or the non-crystalline carbon dioxide-based polyester diol is polypropylene carbonate diol.

6. A method for preparing a polyhydroxyalkanoate polyester as described in any one of claims 1-5, characterized in that, Includes the following steps: The carboxyl-terminated polyester, the amorphous carbon dioxide-based polyester diol, and the polyhydroxy fatty acid ester diol are added to a reaction vessel and heated to 175–200°C. A catalyst of 1‰–2% of the total mass of the carboxyl-terminated polyester, the amorphous carbon dioxide-based polyester diol, and the polyhydroxy fatty acid ester diol is added and reacted for 0.5–5 hours. Then, the reaction is carried out at 200–230°C for 3–4 hours, followed by vacuum polycondensation for 3–6 hours. After cooling, the polyhydroxy fatty acid ester polyester is obtained.

7. The preparation method according to claim 6, characterized in that, Carboxyl-terminated polyester, amorphous carbon dioxide-based polyester diol, and the polyhydroxy fatty acid ester diol are added to a reaction vessel. After heating to 180–200°C, a catalyst of 1 wt‰–5 wt‰ of the total mass of the carboxyl-terminated polyester, amorphous carbon dioxide-based polyester diol, and the polyhydroxy fatty acid ester diol is added. The reaction is carried out for 2–3 hours, followed by a reaction at 210–230°C for 2–4 hours. After vacuum polycondensation for 3–6 hours, the mixture is cooled to room temperature to obtain a polyhydroxy fatty acid ester polyester. The vacuum degree is within 0.5 mmHg.

8. The preparation method according to claim 6, characterized in that, The preparation of the polyhydroxy fatty acid ester diol includes the following steps: adding polyhydroxy fatty acid ester to an organic solvent, adding diol and 1wt‰-2w% of catalyst by total mass, reacting at 30-60℃ for 1-50h, cooling to room temperature, and then concentrating and separating to obtain polyhydroxy fatty acid ester diol; wherein, the molar ratio of polyhydroxy fatty acid ester to diol is 1:(1~20).

9. The method for preparing polyhydroxyalkanoate polyester according to claim 8, characterized in that, Polyhydroxy fatty acid esters are added to an organic solvent, along with a diol and a catalyst of 1 wt‰ to 8 wt‰. The mixture is reacted at 40–50 °C for 2–10 h, cooled to room temperature, and then concentrated and separated to obtain the polyhydroxy fatty acid ester diol. The molar ratio of the polyhydroxy fatty acid ester to the diol is 1:

5. The polyhydroxy fatty acid ester is purified before being added to the organic solvent.

10. The method for preparing polyhydroxyalkanoate polyester according to claim 8, characterized in that, The diols include one or more of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, diethanolamine, 2-amino-2-methyl-1,3-propanediol, 2-amino-1,3-propanediol, 3-amino-1,2-propanediol, and bisphenol A.

11. The application of a polyhydroxyalkanoate polyester according to any one of claims 1-5 or a polyhydroxyalkanoate polyester prepared by any one of claims 6-10, characterized in that, The polyhydroxyalkanoate polyesters are used in adhesives, disposable products, flexible packaging, paper-plastic composites, fibers and nonwovens, foam materials, or agricultural products.

12. A pressure-sensitive adhesive, characterized in that, It comprises the following components in parts by weight: 20 to 99 parts of the polyhydroxyalkanoate polyester as described in any one of claims 1-5, or the polyhydroxyalkanoate polyester prepared by any one of claims 6-10, 20 to 60 parts of tackifying resin, and 0.1 to 10 parts of additives.

13. The pressure-sensitive adhesive according to claim 11, characterized in that, The polyhydroxyalkanoate polyester is 45-80 parts or 50-60 parts; and / or, the additive includes 1-5 parts of plasticizer; and / or, the tackifying resin is 30-60 parts; and / or, the additive includes 0.1-0.2 parts of antioxidant.

14. The pressure-sensitive adhesive according to claim 13, characterized in that, The plasticizer is one or more of epoxidized soybean oil, flaxseed oil, castor oil, and palm oil, and / or the antioxidant is one or more of tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, di(tetrazol) thiodipropionate, and pentaerythritol tetrakis{3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate}.

15. A pressure-sensitive adhesive product, comprising a substrate and a pressure-sensitive adhesive layer adhered to the substrate, characterized in that, The pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive as described in any one of claims 12-14.

16. The pressure-sensitive adhesive according to claim 15, characterized in that, The pressure-sensitive adhesive products include pressure-sensitive adhesive tapes, pressure-sensitive adhesive sticks, labels, and stickers.