A process for the preparation of polyallyl alcohol from CR-39 polymer

Abstract

This invention discloses a method for preparing polyallyl alcohol from CR-39 polymer, belonging to the field of high-value conversion technology of waste resources. Addressing the current problems of CR-39 recycling methods, such as insufficiently mild and environmentally friendly catalytic systems, difficult separation and recovery, the need for resin pretreatment, and high costs, as well as the difficulty in preparing polyallyl alcohol, this invention involves thoroughly mixing CR-39 polymer, solvent, and catalyst, followed by heating and reaction. After the reaction, polyallyl alcohol and other products are separated, and the solvent and catalyst are recovered. This method uses a highly efficient, environmentally friendly, and inexpensive catalyst, is simple to operate, produces high-value-added products, and is environmentally friendly and economical, showing great application prospects.

Description

Technical Field

[0001] This invention belongs to the field of high-value conversion technology of waste resources, specifically relating to a method for preparing polyallyl alcohol from CR-39 polymer. Background Technology

[0002] CR-39, chemically known as polyallyl diethylene glycol carbonate (PADC), is a highly cross-linked thermosetting resin composed of polyallyl chains linked by diethylene glycol dicarbonate, exhibiting a dense three-dimensional network structure. CR-39 possesses excellent properties such as light weight, impact resistance, high light transmittance, wear resistance, corrosion resistance, infrared and ultraviolet radiation resistance, and ease of processing and molding, making it widely used as a material in the production of resin lenses and nuclear track detectors. With the continuous increase in market demand for CR-39, its waste volume has also grown rapidly. Therefore, researching environmentally friendly and efficient CR-39 recycling methods to achieve its high-value recycling is of great significance.

[0003] Heat recovery is energy-intensive and environmentally polluting, physical recovery has a narrow application scope and low economic value, while chemical recovery, with its environmental and economic advantages, has become the mainstream method for recovering polymer materials. Because CR-39 is an ester-bonded polymer, it can be recovered through common chemical methods such as hydrolysis, alcoholysis, and aminolysis to break ester bonds. KNYu et al. studied the alkaline hydrolysis corrosion mechanism of CR-39 in NaOH / water and NaOH / ethanol (Nucl. Instr. and Meth. in Phys. Res. B, 2007, 263, 300–305). However, the traditional strong base catalyst NaOH is highly corrosive and cannot be recovered; it also causes the carbonate bonds in CR-39 to turn into salts, which cannot be retained in the product. Furthermore, both strong bases and strong acids are corrosive, difficult to separate and recover, and easily pollute the environment. Patent CN 103483620A discloses a method for recycling waste thermosetting resin lenses, using alkali metal compounds such as sodium hydroxide and sodium carbonate, and transition metal compounds such as zinc oxide and titanium trichloride as catalysts to catalyze the alcoholysis of CR-39 resin lenses. However, strong alkalis such as sodium hydroxide still have the aforementioned problems, and the separation and recovery of these catalysts are difficult. Furthermore, the metal compounds are expensive and have a certain degree of toxicity to the environment. In addition, the catalytic efficiency of these catalysts decreases or becomes ineffective when exposed to water, therefore, the system must be water-free. Simultaneously, this method requires a high degradation temperature and pre-treatment of the resin lenses into powder, resulting in high energy consumption and operating costs, limiting its industrial application. Furthermore, from the perspective of chemical recovery of other thermosetting resins, the dense three-dimensional network structure of thermosetting resins makes it difficult for solvents and catalysts to penetrate and function. Therefore, in addition to using strong acid or strong base catalysts, additional organic solvents are often added to promote resin swelling to facilitate degradation. However, organic solvents are highly toxic and complicate separation. In summary, current methods for recovering CR-39 suffer from problems such as an insufficiently mild and environmentally friendly catalytic system, difficult separation and recovery, the need for resin pre-treatment, and high costs.

[0004] Meanwhile, CR-39's structure contains three parts: polyallyl alcohol, carbonate bonds, and diethylene glycol. Polyallyl alcohol is a high-performance polymer with significant potential applications in coating materials, adhesives, and packaging. However, direct polymerization of allyl alcohol to prepare polyallyl alcohol is almost impractical. Another method, post-polymerization functionalization, is relatively easy but complex and costly. Therefore, developing an environmentally friendly and efficient CR-39 recycling method to simultaneously recover and prepare high-value chemicals such as polyallyl alcohol and carbonates is of great significance. Summary of the Invention

[0005] In view of the current difficulties in CR-39 recycling and polyallyl alcohol preparation, this invention provides a method for preparing polyallyl alcohol from CR-39 polymers. It uses a mild, green and inexpensive catalyst to achieve efficient and green degradation of CR-39, while preparing high-value chemicals such as polyallyl alcohol. The system is easy to separate and recycle, which not only completes the harmless treatment of waste, but also obtains polyallyl alcohol that is difficult to obtain by conventional methods.

[0006] To achieve the above objectives, the present invention employs the following technical solutions:

[0007] A method for preparing polyallyl alcohol from CR-39 polymer involves thoroughly mixing CR-39 polymer, solvent, and catalyst, then heating the mixture to react. After the reaction is complete, the mixture is cooled to room temperature, and acetone is added until the precipitate is completely formed. The mixture is then filtered, and the filter cake is washed and dried to obtain polyallyl alcohol. The filtrate is distilled, and the fraction collected yields acetone, solvent, catalyst, and carbonate. The residue is diethylene glycol.

[0008] The product polyallyl alcohol was separated, and the solvent and catalyst were recovered.

[0009] The structural formula of the catalyst is:

[0010] In this structure, X is an O or S atom, and R1, R2, and R3 are H atoms, amide groups, urea-alkyl groups, or hydroxyalkyl groups. The catalyst with this structure exhibits weak basicity, enabling gentle catalysis of carbonate bond cleavage in CR-39. Furthermore, the catalyst demonstrates good affinity for both the resin and solvent, readily incorporating the solvent into the resin matrix. Therefore, it exhibits high catalytic activity and requires no resin pretreatment. Moreover, this type of catalyst can be used as feed and fertilizer, is green and non-toxic, inexpensive and readily available, recyclable, and has strong industrial applicability.

[0011] Furthermore, the catalyst is specifically any one of urea, thiourea, isobutylene diurea, biuret, and hydroxymethylurea. These catalysts have good catalytic activity and are environmentally friendly and inexpensive.

[0012] Furthermore, the solvent is any one of water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, ethylene glycol, 1,2-propanediol, and 1,3-propanediol. These solvents have good reactivity with ester bonds, are small in size, easily enter the resin bulk, and have good degradation effects.

[0013] Furthermore, the mass ratio of the CR-39 polymer, solvent, and catalyst is 1:2 to 25:0.4 to 2. Within this ratio range, the catalyst exhibits good catalytic effect, complete resin degradation, and fewer side reactions, which facilitates subsequent separation and improves economic efficiency.

[0014] Furthermore, the reaction temperature is 130–180°C, and the reaction time is 3–20 h. If the reaction temperature is too low, the degradation rate is too slow or the reaction basically does not occur; if the temperature is too high, other chemical bonds will break, making controlled degradation impossible. If the reaction time is too short, the degradation reaction will be incomplete; if the time is too long, side reactions will occur and production efficiency will decrease.

[0015] Furthermore, when the solvent is water, the separation process involves cooling the reaction to room temperature, adding acetone to the system until precipitation is complete, filtering, washing and drying the filter cake to obtain polyallyl alcohol, distilling the filtrate and collecting the fraction to obtain acetone, solvent and catalyst, and the residue is diethylene glycol.

[0016] When the solvent is alcohol, the separation process involves cooling the reaction to room temperature, adding acetone to the system until precipitation is complete, filtering, washing and drying the filter cake to obtain polyallyl alcohol, distilling the filtrate, collecting the distillate to obtain acetone, solvent, carbonate, and catalyst, and the residue to obtain diethylene glycol. This method is simple to operate, generates no waste, and all components can be recycled.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The catalyst used in this invention can mildly and efficiently catalyze the degradation of CR-39, and the catalyst is green, economical, recyclable, and has strong industrial applicability.

[0019] 2. This invention not only achieves efficient and green degradation of CR-39, but also prepares high-value-added products such as polyallyl alcohol, realizing high-value recovery of CR-39.

[0020] 3. The resin of this invention requires no pretreatment, the method is mild and simple, environmentally friendly and economical, and easy to industrialize. Attached Figure Description

[0021] Figure 1 The degradation product polyallyl alcohol in Example 1 1 HNMR spectrum;

[0022] Figure 2 The degradation product polyallyl alcohol in Example 1 13 CNMR spectrum;

[0023] Figure 3 This is a gel permeation chromatogram of polyallyl alcohol, the degradation product in Example 1;

[0024] Figure 4 The degradation product dimethyl carbonate in Example 1 1 HNMR spectrum;

[0025] Figure 5 The degradation product dimethyl carbonate in Example 1 13 CNMR spectrum;

[0026] Figure 6 The degradation product diethylene glycol in Example 1 1 HNMR spectrum;

[0027] Figure 7 The degradation product diethylene glycol in Example 1 13 CNMR spectrum. Detailed Implementation

[0028] The present invention will now be clearly and completely described with reference to the accompanying drawings and specific embodiments, but this does not limit the scope of protection of the present invention.

[0029] Example 1

[0030] 1.0g of waste CR-39 lenses, 5.1g of methanol, and 0.6g of urea were thoroughly mixed and heated at 140℃ for 16 hours. After cooling, the resin was completely degraded. Acetone was added to the degradation solution until precipitation was complete. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which was polyallyl alcohol. Figure 1 — Figure 3 After distillation of the filtrate, the fraction collected yielded acetone, methanol, and dimethyl carbonate. Figure 4 and Figure 5 ) and urea, the residue after distillation is diethylene glycol ( Figure 6 and Figure 7 ).

[0031] Example 2

[0032] 1.0 g of waste CR-39 lenses, 9.0 g of ethanol, and 1.2 g of biuret were thoroughly mixed and heated at 155 °C for 14 h. After the reaction, the mixture was cooled, and the resin was completely degraded. Acetone was added to the degradation solution until the precipitate was completely formed. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which was polyallyl alcohol. The filtrate was distilled, and the fractions collected yielded acetone, ethanol, diethyl carbonate, and biuret. The residue was diethylene glycol.

[0033] Example 3

[0034] 1.0 g of waste CR-39 lenses, 2.0 g of n-propanol, and 0.7 g of biuret recovered in Example 2 were thoroughly mixed and heated to react at 150 °C for 11 h. After the reaction, the mixture was cooled, and the resin was completely degraded. Acetone was added to the degradation solution until the precipitation was complete. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which was polyallyl alcohol. After distillation of the filtrate, the fractions were collected to obtain acetone, n-propanol, di-n-propyl carbonate, and biuret. The residue was diethylene glycol.

[0035] Example 4

[0036] 1.0 g of waste CR-39 lenses, 15.7 g of water, and 1.4 g of biuret were thoroughly mixed and heated at 135 °C for 18 h. After the reaction, the mixture was cooled, and the resin was completely degraded. Acetone was added to the degradation solution until the precipitate was completely formed. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which is polyallyl alcohol. The filtrate was distilled, and the fractions collected yielded acetone, water, and biuret. The residue was diethylene glycol.

[0037] Example 5

[0038] 1.0 g of waste CR-39 lenses, 8.4 g of n-butanol, and 1.3 g of hydroxymethylurea were thoroughly mixed and heated to 158 °C for 10 h. After cooling, the resin was completely degraded. Acetone was added to the degradation solution until precipitation was complete. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which was polyallyl alcohol. The filtrate was distilled, and the fraction collected yielded acetone, n-butanol, di-n-butyl carbonate, and hydroxymethylurea. The residue was diethylene glycol.

[0039] Example 6

[0040] 1.0g of waste CR-39 lenses, 6.9g of isopropanol, and 0.4g of urea were thoroughly mixed and heated at 145℃ for 15 hours. After the reaction, the mixture was cooled, and the resin was completely degraded. Acetone was added to the degradation solution until the precipitate was completely formed. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which is polyallyl alcohol. The filtrate was distilled, and the fraction collected yielded acetone, isopropanol, diisopropyl carbonate, and urea. The residue was diethylene glycol.

[0041] Example 7

[0042] 1.0 g of waste CR-39 lenses, 13.3 g of isobutanol, and 0.9 g of isobutylene diurea were thoroughly mixed and heated at 160 °C for 9 h. After the reaction, the mixture was cooled, and the resin was completely degraded. Acetone was added to the degradation solution until the precipitate was completely formed. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which was polyallyl alcohol. The filtrate was distilled, and the fraction collected yielded acetone, isobutanol, diisobutyl carbonate, and isobutylene diurea. The residue was diethylene glycol.

[0043] Example 8

[0044] 1.0 g of waste CR-39 lenses, 14.2 g of sec-butanol, and 1.6 g of thiourea were thoroughly mixed and heated at 130 °C for 20 h. After the reaction, the mixture was cooled, and the resin was completely degraded. Acetone was added to the degradation solution until the precipitate was completely formed. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which was polyallyl alcohol. The filtrate was distilled, and the fraction collected yielded acetone, sec-butanol, disec-butyl carbonate, and thiourea. The residue was diethylene glycol.

[0045] Example 9

[0046] 1.0 g of waste CR-39 lenses, 17.0 g of tert-butanol, and 1.1 g of thiourea recovered in Example 7 were thoroughly mixed and heated to react at 165 °C for 7 h. After the reaction, the mixture was cooled, and the resin was completely degraded. Acetone was added to the degradation solution until the precipitation was complete. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which was polyallyl alcohol. After distillation of the filtrate, the fractions were collected to obtain acetone, tert-butanol, di-tert-butyl carbonate, and thiourea. The residue was diethylene glycol.

[0047] Example 10

[0048] 1.0 g of waste CR-39 lenses, 19.6 g of ethylene glycol, and 2.0 g of isobutylene diurea were thoroughly mixed and heated at 170 °C for 5 h. After the reaction, the mixture was cooled, and the resin was completely degraded. Acetone was added to the degradation solution until the precipitate was completely formed. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which was polyallyl alcohol. The filtrate was distilled, and the fraction collected yielded acetone, ethylene glycol, ethylene carbonate, and isobutylene diurea. The residue was diethylene glycol.

[0049] Example 11

[0050] 1.0 g of waste CR-39 lenses, 25.0 g of 1,2-propanediol, and 1.8 g of urea were thoroughly mixed and heated at 175 °C for 6 h. After the reaction, the mixture was cooled, and the resin was completely degraded. Acetone was added to the degradation solution until the precipitate was completely formed. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which was polyallyl alcohol. The filtrate was distilled, and the fraction collected yielded acetone, 1,2-propanediol, 1,2-propanediol carbonate, and urea. The residue was diethylene glycol.

[0051] Example 12

[0052] 1.0 g of waste CR-39 lenses, 22.6 g of 1,3-propanediol, and 1.9 g of hydroxymethylurea were thoroughly mixed and heated at 180 °C for 3 h. After the reaction, the mixture was cooled, and the resin was completely degraded. Acetone was added to the degradation solution until the precipitate was completely formed. The mixture was filtered, and the filter cake was washed and dried to obtain a white solid, which was polyallyl alcohol. The filtrate was distilled, and the fraction collected yielded acetone, 1,3-propanediol, 1,3-propanediol carbonate, and hydroxymethylurea. The residue was diethylene glycol.

[0053] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.

Claims

1. A method of making a polyallyl alcohol from CR-39 polymer, characterized by: After the CR-39 polymer, solvent and catalyst are thoroughly mixed, the mixture is heated to react. After the reaction is completed, the mixture is cooled to room temperature, and acetone is added until the precipitate is completely formed. The mixture is filtered, and the filter cake is washed and dried to obtain polyallyl alcohol. The filtrate is distilled and the fractions are collected to obtain acetone, solvent, catalyst and carbonate. The residue is diethylene glycol. The product polyallyl alcohol was separated, and the solvent and catalyst were recovered. The structural formula of the catalyst is: ; Where X is an O atom or an S atom, and R1, R2 and R3 are H atoms, amide groups, urea alkyl groups or hydroxyalkyl groups; The solvent is any one of water, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, ethylene glycol, 1,2-propanediol, and 1,3-propanediol.

2. The process for preparing polyallyl alcohol from CR-39 polymer according to claim 1, characterized in that: The catalyst is specifically any one of urea, thiourea, isobutylene diurea, biuret, and hydroxymethylurea.

3. The method for preparing polyallyl alcohol from CR-39 polymer according to claim 1, characterized in that: The mass ratio of the CR-39 polymer, solvent, and catalyst is 1:2 to 25:0.4 to 2.

4. The method for preparing polyallyl alcohol from CR-39 polymer according to claim 1, characterized in that: The heating reaction is carried out at a temperature of 130–180°C for 3–20 h.

5. The method for preparing polyallyl alcohol from CR-39 polymer according to claim 1, characterized in that: When the solvent is water, the separation process is as follows: after the reaction, the mixture is cooled to room temperature, acetone is added to the system until the precipitation is complete, the mixture is filtered, the filter cake is washed and dried to obtain polyallyl alcohol, the filtrate is distilled and the fraction is collected to obtain acetone, solvent and catalyst, and the residue is diethylene glycol.

6. The method for preparing polyallyl alcohol from CR-39 polymer according to claim 1, characterized in that: When the solvent is alcohol, the separation process is as follows: after the reaction, the mixture is cooled to room temperature, acetone is added to the system until the precipitation is complete, the mixture is filtered, the filter cake is washed and dried to obtain polyallyl alcohol, the filtrate is distilled and the fraction is collected to obtain acetone, solvent, carbonate and catalyst, and the residue is diethylene glycol.

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