An unsaturated polyester resin for optical cable reinforcing core and a method for preparing the same

Abstract

The application relates to an unsaturated polyester resin for optical cable reinforcing cores and a preparation method thereof, and belongs to the technical field of unsaturated resins. The unsaturated polyester resin is prepared from the following components: PG, IPA, a catalyst, maleic anhydride, AA, styrene, an antioxidant, a first, a second and a third polymerization inhibitor; the alcohol acid ratio is 1.08-1.12:1; the activity is 3.4-3.8:1; the molar ratio of AA and IPA is 1:12-16; and the preparation steps are as follows: 1) uniformly mixing propylene glycol, a catalyst and isophthalic acid; 2) heating, keeping warm, and then heating again; cooling and then adding the first polymerization inhibitor, maleic anhydride and adipic acid in sequence, heating, keeping warm, and then heating again; 3) cooling and then adding the second polymerization inhibitor; and 4) cooling and then adding styrene, the third polymerization inhibitor and the antioxidant, uniformly mixing, and cooling to <=60 DEG C to obtain the unsaturated polyester resin for optical cable reinforcing cores. The unsaturated polyester resin for optical cable reinforcing cores has the characteristics of high bending strength and high temperature resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of unsaturated resins, and particularly relates to an unsaturated polyester resin for optical cable reinforcing cores and a preparation method thereof. BACKGROUND

[0002] In the field of optical cable manufacturing, the optical cable reinforcing core is a core component that guarantees the stability of the optical cable structure, and its performance directly determines the service life and reliability of the optical cable in complex environments. As the "skeleton" of the optical cable, the reinforcing core needs to have excellent bending strength and outstanding heat resistance to cope with various harsh working conditions such as underground burial, high-altitude erection, and large temperature differences.

[0003] Currently, the preparation scheme of the resin for the optical cable reinforcing core is to mix and blend unsaturated polyester resin and vinyl resin in a certain proportion. Among them, the vinyl resin can improve the high-temperature resistance of the composite material due to its unique cross-linking system in the molecular structure, so that the reinforcing core remains structurally stable. However, this mixing mode has unavoidable shortcomings. First, the cost of vinyl resin is relatively high, increasing the production cost of the optical cable reinforcing core. In the context of continuous compression of profit space in the optical cable industry, this has become a major obstacle to cost reduction and efficiency improvement for enterprises. Second, the compatibility of the two resins needs to be guaranteed by precisely controlling the stirring rate, temperature gradient, and curing time. The additional precision monitoring equipment required for the mixing process not only prolongs the production cycle but also may introduce defects such as air bubbles and stratification due to fluctuations in operating parameters, resulting in a decrease in product pass rate.

[0004] The Chinese invention patent with the title "Preparation method of heat-resistant unsaturated polyester resin" with the publication number CN111253557A uses phthalic anhydride, maleic anhydride, and isophthalic acid as raw materials to prepare a heat-resistant unsaturated polyester resin through step-by-step temperature rising reaction under the action of specific composite catalysts and polymerization inhibitors. However, the bending strength and toughness of the resin are insufficient, and the high reaction temperature leads to high energy consumption.

[0005] The function of the optical cable reinforcing core is to provide overall rigidity to the optical cable, avoid the optical cable from sagging due to its own weight when laid over a long distance (such as overhead optical cable), and ensure the stability of the cross-sectional shape of the optical cable for easy splicing and maintenance. High-altitude erection needs to withstand high daytime sunlight temperatures, plus the heat generated by the optical cable communication itself, so there are strict requirements for heat resistance and bending strength. Low bending strength cannot provide support, and poor heat resistance can cause cracks when heated.

[0006] As can be seen from the above description, the existing resin for optical cable reinforcing cores has the problems of low bending strength and poor heat resistance. SUMMARY

[0007] The technical problem solved by the present application is to overcome the shortcomings of the prior art and provide an unsaturated polyester resin for optical cable reinforcing cores and a preparation method thereof.

[0008] To achieve the above-mentioned object, the present application provides an unsaturated polyester resin for optical cable reinforcing cores, which is composed of the following components in parts by weight: 600-760 parts of propylene glycol, 254.6-290.6 parts of isophthalic acid, 0.26-1.45 parts of a catalyst, 553.6-692.7 parts of maleic anhydride, 15.9-18.7 parts of adipic acid, 0.038-0.046 parts of a first polymerization inhibitor, 0.17-0.21 parts of a second polymerization inhibitor, 790-911 parts of styrene, 0.034-0.041 parts of a third polymerization inhibitor, and 0.34-0.41 parts of an antioxidant; the molar ratio of total alcohol to total acid is 1.08-1.12:1; the molar ratio of unsaturated acid to saturated acid is 3.4-3.8:1; and the molar ratio of adipic acid to isophthalic acid is 1:12-16.

[0009] The first polymerization inhibitor, the second polymerization inhibitor, and the third polymerization inhibitor are at least one of methylhydroquinone, hydroquinone, and copper naphthenate; the catalyst is monobutyl tin oxide or zinc acetate, and the zinc acetate used in the present application is zinc acetate dihydrate; the antioxidant is dibutylhydroxytoluene, abbreviated as BHT; and the copper naphthenate in the present application is 8% copper naphthenate, indicating that the mass percentage of copper content is 8%. Preferably, the first polymerization inhibitor is methylhydroquinone, the second polymerization inhibitor is hydroquinone, and the third polymerization inhibitor is copper naphthenate.

[0010] The molar ratio of total alcohol to total acid is referred to as the alcohol-acid ratio, and the molar ratio of total alcohol to total acid in the range of 1.08-1.12:1 can make the alcohol and acid fully react to form a high-molecular-weight polymer with a complete molecular chain structure, thereby imparting the optical cable reinforcing core with higher tensile strength and toughness to meet the requirements of the optical cable in resisting tensile and bending mechanical stress in complex environments. A too low or too high molar ratio of total alcohol to total acid can result in a low molecular weight, insufficient crosslinking density of the resin, and decreased mechanical properties, thereby affecting the long-term stability of the optical cable.

[0011] The activity is the molar ratio of unsaturated acid to saturated acid; the molar ratio of unsaturated acid to saturated acid is in the range of 3.4-3.8:1, which can optimize the mechanical properties and thermal stability of the optical cable reinforcing core by adjusting the molecular chain structure and crosslinking density. The higher the ratio of unsaturated acid to saturated acid, the higher the activity and the mechanical strength, and the higher the heat distortion temperature, but the toughness will decrease, become brittle, and the elongation at break will be lower; therefore, it is not necessarily good to be high, nor is it necessarily good to be low, the activity of the present application can balance the mechanical strength and elongation at break, and this balance can meet the performance requirements of the unsaturated polyester resin for optical cable reinforcing cores. When the activity is too high, excessive maleic anhydride leads to intense heat release during the reaction, increasing the risk of gelation; when the activity is too low, insufficient crosslinking prolongs the curing time.

[0012] The molar ratio of adipic acid to isophthalic acid is controlled in the range of 1:12-16, adipic acid plays a role in improving toughness, isophthalic acid dominates strength and heat resistance, and by adjusting the molecular chain structure, the required high rigidity, heat resistance and moderate toughness of the optical cable reinforcing core are achieved; the use of unsaturated polyester resin can realize high bending strength and high temperature resistance of the material; this achievement effectively solves the problems of high cost and complex process caused by the use of mixed resin in the prior art. The present application avoids the use of high-cost vinyl resin and only uses unsaturated polyester resin for optical cable reinforcing cores as raw materials, greatly reducing the production cost of the optical cable reinforcing core, and the cost of the present application can be reduced by 20-30% compared with the traditional mixed resin. The high proportion of isophthalic acid reaches 12-16 times of adipic acid, and the high proportion of isophthalic acid constructs a rigid skeleton, which greatly improves the regularity and packing density of the molecular chain, and makes the cured resin form a high-crosslinking rigid network. The high thermal stability of the benzene ring effectively resists the thermal stress of the optical cable operating environment and avoids softening and deformation at high temperature. The toughening effect of adipic acid breaks the excessive rigidity arrangement, absorbs external impact energy, improves the elongation at break, and prevents brittle fracture.

[0013] In weight parts, it is composed of the following components: propylene glycol 640-720 parts, isophthalic acid 264.6-282.6 parts, catalyst 0.53-1.13 parts, maleic anhydride 553.6-692.7 parts, adipic acid 15.9-18.7 parts, first polymerization inhibitor 0.038-0.046 parts, second polymerization inhibitor 0.17-0.21 parts, styrene 790-911 parts, third polymerization inhibitor 0.034-0.041 parts, and antioxidant 0.34-0.41 parts.

[0014] Preferably, the molar ratio of total alcohol to total acid is 1.09-1.11:1; it ensures that the carboxyl group is fully esterified, avoids residual acid-induced hydrolytic degradation, improves the uniformity of the molecular chain length, reduces the residue of oligomers, and reduces the curing shrinkage stress. The unsaturated polyester resin for optical cable reinforcing cores obtained under this proportion has excellent heat distortion temperature, tensile strength, bending strength and toughness.

[0015] Preferably, the molar ratio of unsaturated acid to saturated acid is 3.5-3.7:1; the balance between crosslinking density and molecular chain flexibility is optimized to achieve the best effect of mechanical strength, heat resistance and reactivity.

[0016] Preferably, the molar ratio of adipic acid to isophthalic acid is 1:13-15; by adjusting the ratio of molecular chain rigidity to flexible segment, the optimal balance of mechanical strength, heat resistance and toughness is achieved.

[0017] Preferably, propylene glycol 680 parts, isophthalic acid 273.9 parts, catalyst 0.82 parts, maleic anhydride 623.8 parts, adipic acid 17.2 parts, first polymerization inhibitor 0.04 parts, second polymerization inhibitor 0.19 parts, styrene 851 parts, third polymerization inhibitor 0.038 parts, antioxidant 0.38 parts; the molar ratio of total alcohol to total acid is 1.10:1; the molar ratio of unsaturated acid to saturated acid is 3.6:1; the molar ratio of adipic acid to isophthalic acid is 1:14; the catalyst is monobutyl tin oxide.

[0018] The present application also provides a preparation method of unsaturated polyester resin for optical cable reinforcing core, comprising the following steps:

[0019] (1) add propylene glycol, catalyst and isophthalic acid according to weight parts into a reaction container and mix uniformly;

[0020] (2) warm the product obtained in step (1), keep warm, and then warm up again to react until the acid value is 15-20 mgKOH / g; after cooling, add first polymerization inhibitor, maleic anhydride and adipic acid according to weight parts in turn, warm up, keep warm, and then warm up again to react until the acid value is 10-15 mgKOH / g;

[0021] (3) after cooling the product obtained in step (2), add second polymerization inhibitor according to weight parts;

[0022] (4) after cooling the product obtained in step (3), add styrene, third polymerization inhibitor and antioxidant according to weight parts, mix uniformly, and then cool to ≤60℃ to obtain unsaturated polyester resin for optical cable reinforcing core.

[0023] The reactions in steps (1) and (2) are both carried out under inert gas protection; inert gas protection can prevent oxidative degradation and discoloration, reduce hydrolysis and free radical side reactions, inhibit monomer volatilization, isolate water vapor and pollutants, and improve the consistency of rigidity, heat resistance and toughness of the final product. The inert gas used in steps (1) and (2) is nitrogen.

[0024] The specific operation of step (1) is to add propylene glycol, catalyst and isophthalic acid according to weight parts into a reaction container, mix uniformly under the protection of inert gas; the stirring rate of step (1) is 110-130 r / min.

[0025] The specific operation of step (2) is to heat the product of step (1) to 185-190°C under the protection of inert gas to react out water, and then keep the temperature for 0.5-1 h, and then heat to 200-205°C at a rate of 15-18°C / h to react until the acid value is 15-20 mgKOH / g; after cooling to 135-140°C, add the first polymerization inhibitor, maleic anhydride and adipic acid in turn by weight, heat to 165-170°C to react out water, keep the temperature for 0.5-1 h, and then heat to 205-210°C at a rate of 15-18°C / h to keep the temperature and react until the acid value is 10-15 mgKOH / g. The stirring speed of step (2) is 230-250 r / min. The temperature keeping stage at 165-170°C can promote the ring opening of maleic anhydride and the preliminary esterification reaction with adipic acid; heating to 205-210°C at a rate of 15-18°C / h can reduce the loss caused by the volatilization of alcohol and acid during synthesis, and ensure economic benefits.

[0026] The specific operation of step (3) is to cool to 150-160°C, and then add the second polymerization inhibitor by weight. The stirring speed of step (3) is 230-250 r / min.

[0027] Step (4) is to cool the product of step (3) to 120-130°C, and then add styrene, the third polymerization inhibitor and the antioxidant by weight, stir and mix uniformly, and then cool to ≤60°C to obtain the unsaturated polyester resin for optical cable reinforcing core. The stirring speed of step (4) is 390-410 r / min; 150-160°C is the temperature window for the effective action of the polymerization inhibitor, which can inhibit the premature polymerization of the residual double bond of maleic anhydride, and avoid the decomposition of the polymerization inhibitor caused by high temperature. 120-130°C can ensure uniform mixing and non-volatilization, and provide active diluent for subsequent crosslinking and curing.

[0028] The cooling rate of each step of the present application does not affect the bending strength and temperature resistance of the final product. The addition of the first polymerization inhibitor prevents the risk of difficult control or even curing caused by too fast self-polymerization of the resin during synthesis; the second polymerization inhibitor is adapted to the temperature window of 150-160°C, and the addition of the second polymerization inhibitor can prevent premature crosslinking of the system during cooling due to residual active free radicals. If premature crosslinking occurs, it will cause gelation risk. The third polymerization inhibitor is added at 120-130°C at the same time as styrene, which is easy to polymerize under heat or light. The addition of the third polymerization inhibitor can avoid the gelation problem caused by local overheating during dilution and cooling, and ensure that each stage of reaction proceeds as expected. If the second polymerization inhibitor and the third polymerization inhibitor are added at the same time, it will affect the gelation time of the resin.

[0029] The application can guarantee the stability of resin synthesis process, make total alcohol and total acid fully react to form high molecular weight polymer, and ensure the crosslinking density balance of unsaturated acid and saturated acid, so that the resin molecular chain is regular, and the packing density is reasonable. The symmetrical benzene ring structure of isophthalic acid can fully improve the heat resistance, and the adipic acid can effectively enhance the toughness, so as to realize the synergistic effect of high bending strength and high heat resistance. Isophthalic acid and adipic acid are raw materials with low reactivity, and if they are added at the same time, the synthesis speed is slow, the period is too long, and the reaction is difficult to complete. The long reaction period not only causes the resin color to be black, affecting the appearance of the product, but also increases the production consumption, which is not conducive to improving the economic benefit. The incomplete reaction will reduce the mechanical properties and heat resistance of the product, and the long reaction period not only increases the production consumption, which is not conducive to improving the economic benefit, but also causes the resin color to be black, affecting the appearance of the product.

[0030] Compared with the prior art, the application has the beneficial effects that:

[0031] 1. The unsaturated polyester resin for optical cable reinforcing core has the characteristics of high bending strength and high heat resistance, the adipic acid plays a role in improving toughness, the isophthalic acid dominates the enhancement of strength and heat resistance, and through the regulation of the molecular chain structure, the synergistic balance of high rigidity, heat resistance and moderate toughness required by the optical cable reinforcing core is realized. The use of the unsaturated polyester resin for optical cable reinforcing core can realize the high bending strength and high heat resistance of the material. The total alcohol and total acid molar ratio can ensure the formation of high molecular weight polymer, and guarantee the tensile strength and toughness. The molar ratio of unsaturated acid and saturated acid can balance the mechanical strength, elongation at break and thermal stability, and avoid the risk of gel or curing delay caused by too high or too low. The tensile strength of the unsaturated polyester resin for optical cable reinforcing core is 85.08-98.48 MPa, the tensile elastic modulus is 3623.0-3926.5 MPa, the elongation at break is 2.61-3.55%, the bending strength is 132.1-138.8 MPa, the bending elastic modulus is 3765.4-3920.3 MPa, and the heat distortion temperature is 133.6-139.3℃.

[0032] 2. The unsaturated polyester resin for optical cable reinforcing core has simple process and low cost, and does not need to mix other resins, and can save raw materials and energy consumption. DETAILED DESCRIPTION

[0033] Example 3 is the best embodiment of the application, and the application will be further described in combination with specific examples and comparative examples.

[0034] The chemical additives used in the examples and comparative examples of the application are all commercially available, and the specific information is as follows:

[0035] Propylene glycol: purchased from Cangzhou Jinzhan Chemical Co., Ltd.

[0036] Isophthalic acid: purchased from Jiangsu Zhaohua Chemical Co., Ltd.

[0037] Monobutyl tin oxide: purchased from Changzhou Yurong Chemical Co., Ltd.

[0038] Zinc acetate dihydrate: purchased from Guangzhou Yuan Shu Chemical Technology Development Co., Ltd.

[0039] Methylhydroquinone: purchased from Changzhou Yurong Chemical Co., Ltd.

[0040] p-Benzenediol: industrial grade, purchased from Changzhou Yurong Chemical Co., Ltd.

[0041] 8% Copper naphthenate: purchased from Shanghai Taoyuan Cobalt Co., Ltd.

[0042] BHT: industrial grade, purchased from Changzhou Yurong Chemical Co., Ltd.

[0043] Maleic anhydride: purchased from Wanhua Chemical Group Petrochemical Sales Co., Ltd.

[0044] Adipic acid: purchased from Ningbo Zhongxing New Material Technology Co., Ltd.

[0045] Styrene: purchased from Shenyang Jinhua Petrochemical Co., Ltd.

[0046] Cobalt isooctoate type EC-12: purchased from Jipei Chemical (Shanghai) Co., Ltd.

[0047] Methyl ethyl ketone peroxide: purchased from Qingdao Feiyang Commerce and Trade Co., Ltd.

[0048] Table 1 Raw materials of examples (in parts by weight)

[0049] .

[0050] Example 1

[0051] A preparation method of an unsaturated polyester resin for an optical cable reinforcing core, comprising the following steps:

[0052] (1) Put propylene glycol, catalyst and isophthalic acid according to weight parts into a reaction container, mix under the protection of nitrogen; the stirring rate of step (1) is 130 r / min;

[0053] (2) the product obtained in step (1) is heated to 185°C under the protection of nitrogen, and water is removed after reaction, and then kept for 0.5 h, and then heated to 200°C at a rate of 15°C / h, and kept for reaction until the acid value is 15 mgKOH / g; cooled to 135°C, and then added with the first polymerization inhibitor, maleic anhydride and adipic acid according to weight parts, respectively, and then heated to 165°C under stirring, and water is removed after reaction, and then kept for 0.5 h, and then heated to 205°C at a rate of 15°C / h, and kept for reaction until the acid value is 10 mgKOH / g; the stirring rate in step (2) is 250 r / min;

[0054] (3) the product obtained in step (2) is cooled to 150°C, and then added with the second polymerization inhibitor according to weight parts, and the stirring rate in step (3) is 250 r / min;

[0055] (4) the product obtained in step (3) is cooled to 120°C, and then added with styrene, the third polymerization inhibitor and the antioxidant according to weight parts, and then mixed uniformly, and then cooled to ≤60°C, to obtain the unsaturated polyester resin for optical cable reinforcing core; the stirring rate in step (4) is 410 r / min.

[0056] Example 2

[0057] A preparation method of an unsaturated polyester resin for optical cable reinforcing core, which comprises the following steps:

[0058] (1) propylene glycol, a catalyst and isophthalic acid are added into a reaction container according to weight parts, and then mixed uniformly under the protection of nitrogen, and the stirring rate in step (1) is 110 r / min;

[0059] (2) the product obtained in step (1) is heated to 190°C under the protection of nitrogen, and water is removed after reaction, and then kept for 1 h, and then heated to 205°C at a rate of 18°C / h, and kept for reaction until the acid value is 20 mgKOH / g; cooled to 140°C, and then added with the first polymerization inhibitor, maleic anhydride and adipic acid according to weight parts, respectively, and then heated to 170°C under the protection of nitrogen, and water is removed after reaction, and then kept for 1 h, and then heated to 210°C at a rate of 18°C / h, and kept for reaction until the acid value is 15 mgKOH / g; the stirring rate in step (2) is 230 r / min;

[0060] (3) the product obtained in step (2) is cooled to 160°C, and then added with the second polymerization inhibitor according to weight parts, and the stirring rate in step (3) is 230 r / min;

[0061] (4) the product obtained in step (3) is cooled to 130°C, and then added with styrene, the third polymerization inhibitor and the antioxidant according to weight parts, and then mixed uniformly, and then cooled to ≤60°C, to obtain the unsaturated polyester resin for optical cable reinforcing core; the stirring rate in step (4) is 390 r / min.

[0062] Example 3

[0063] A method for preparing unsaturated polyester resin for optical cable reinforcing cores comprises the following steps:

[0064] (1) Add propylene glycol, catalyst and isophthalic acid to the reaction vessel according to the weight parts, and mix them under the protection of nitrogen; the stirring rate in step (1) is 120 r / min;

[0065] (2) Under the protection of nitrogen, the product obtained in step (1) is heated to 187°C and reacted to produce water. After the water is produced, the temperature is maintained for 0.7 h. Then, the temperature is increased to 203°C at a rate of 16°C / h and reacted until the acid value is 18 mg KOH / g. The temperature is lowered to 137°C and the first polymerization inhibitor, maleic anhydride and adipic acid are added in sequence according to the weight parts. After the water is produced, the temperature is increased to 177°C and reacted to produce water. After the water is produced, the temperature is maintained for 0.7 h. Then, the temperature is increased to 207°C at a rate of 17°C / h and reacted until the acid value is 13 mg KOH / g. The stirring rate in step (2) is 240 r / min.

[0066] (3) After cooling the product obtained in step (2) to 155°C, add the second polymerization inhibitor according to the weight parts; the stirring rate in step (3) is 240 r / min;

[0067] (4) After cooling the product obtained in step (3) to 125°C, add styrene, third polymerization inhibitor and antioxidant by weight, mix well, and then cool to ≤60°C to obtain unsaturated polyester resin for optical cable reinforcing core; the stirring rate in step (4) is 400r / min.

[0068] Example 4

[0069] A method for preparing unsaturated polyester resin for optical cable reinforcing cores comprises the following steps:

[0070] (1) Add propylene glycol, catalyst and isophthalic acid to the reaction vessel according to the weight parts, and mix them under the protection of nitrogen; the stirring rate in step (1) is 120 r / min;

[0071] (2) Under nitrogen protection, the product obtained in step (1) was heated to 187°C and reacted to produce water. After holding the temperature for 0.7 h, the temperature was increased to 203°C at a rate of 16°C / h and reacted until the acid value was 18 mg KOH / g. The temperature was then lowered to 137°C and the first polymerization inhibitor, maleic anhydride and adipic acid were added in sequence according to the weight parts. Under nitrogen protection, the temperature was increased to 177°C and reacted to produce water. After holding the temperature for 0.7 h, the temperature was increased to 207°C at a rate of 17°C / h and reacted until the acid value was 11 mg KOH / g. The stirring rate in step (2) was 240 r / min.

[0072] (3) After cooling the product obtained in step (2) to 155°C, add the second polymerization inhibitor according to the weight parts; the stirring rate in step (3) is 240 r / min;

[0073] (4) After cooling the product obtained in step (3) to 125°C, add styrene, third polymerization inhibitor and antioxidant by weight, mix well, and then cool to ≤60°C to obtain unsaturated polyester resin for optical cable reinforcing core; the stirring rate in step (4) is 400r / min.

[0074] Example 5

[0075] A method for preparing unsaturated polyester resin for optical cable reinforcing cores comprises the following steps:

[0076] (1) Add propylene glycol, catalyst and isophthalic acid to the reaction vessel according to the weight parts, and mix them under the protection of nitrogen; the stirring rate in step (1) is 120 r / min;

[0077] (2) Under nitrogen protection, the product obtained in step (1) was heated to 187°C and reacted to produce water. After the water was produced, the temperature was maintained for 0.7 h. Then, the temperature was increased to 203°C at a rate of 16°C / h and reacted until the acid value was 18 mg KOH / g. The temperature was lowered to 137°C and the first polymerization inhibitor, maleic anhydride and adipic acid were added in sequence according to the weight parts. Under nitrogen protection, the temperature was increased to 177°C and reacted to produce water. After the water was produced, the temperature was maintained for 0.7 h. Then, the temperature was increased to 207°C at a rate of 17°C / h and reacted until the acid value was 14 mg KOH / g. The stirring rate in step (2) was 240 r / min.

[0078] (3) After cooling the product obtained in step (2) to 155°C, add the second polymerization inhibitor according to the weight parts. The stirring rate in step (3) is 240 r / min.

[0079] (4) After cooling the product obtained in step (3) to 125°C, add styrene, third polymerization inhibitor and antioxidant by weight, mix well, and then cool to ≤60°C to obtain unsaturated polyester resin for optical cable reinforcing core; the stirring rate in step (4) is 400r / min.

[0080] Comparative Example 1

[0081] The preparation method of the unsaturated polyester resin for the optical cable reinforcing core described in this comparative example is the same as that in Example 3, except that the alkyd-acid ratio is too low. For the specific formula, please refer to Table 2.

[0082] Comparative Example 2

[0083] The preparation method of the unsaturated polyester resin for the optical cable reinforcing core described in this comparative example is the same as that in Example 3, except that the alkyd-acid ratio is too high. For the specific formula, please refer to Table 2.

[0084] Comparative Example 3

[0085] The preparation method of the unsaturated polyester resin for the optical cable reinforcing core described in this comparative example is the same as that in Example 3, except that the activity is too low. For the specific formula, please refer to Table 2.

[0086] Comparative Example 4

[0087] The preparation method of the unsaturated polyester resin for optical cable reinforcing core described in this comparative example is the same as that in Example 3, except that the activity is too high. For the specific formula, please refer to Table 2.

[0088] Comparative Example 5

[0089] The preparation method of the unsaturated polyester resin for the optical cable reinforcing core described in this comparative example is the same as that in Example 3, except that the molar ratio of adipic acid and isophthalic acid is too low. For the specific formula, please refer to Table 2.

[0090] Comparative Example 6

[0091] The preparation method of the unsaturated polyester resin for the optical cable reinforcing core described in this comparative example is the same as that in Example 3, except that the molar ratio of adipic acid and isophthalic acid is too high. For the specific formula, please refer to Table 2.

[0092] Comparative Example 7

[0093] The formulation of the unsaturated polyester resin for the optical cable reinforcing core described in this comparative example is the same as that in Example 3, except that (1) propylene glycol, catalyst, isophthalic acid and adipic acid are added to the reaction vessel in parts by weight and mixed under nitrogen protection.

[0094] Table 2 shows the raw materials (by weight) for Comparative Examples 1-6.

[0095] .

[0096] Performance testing

[0097] The performance of the unsaturated polyester resin used for the optical cable reinforcing core prepared in the examples and comparative examples was tested, and the specific test results are shown in Table 3.

[0098] 1% cobalt isooctanoate accelerator was added to the unsaturated polyester resin for optical cable reinforcing core prepared in the examples and comparative examples, and stirred evenly. Then, 1.5% methyl ethyl ketone peroxide initiator was added and stirred evenly. The mixture was poured into a steel mold with dimensions of 350mm×300mm×5mm and cured at 21~25℃ for 24 hours to obtain an unsaturated polyester resin casting for optical cable reinforcing core.

[0099] Tensile strength was tested in accordance with standard GB / T2567-2021;

[0100] The tensile modulus of elasticity was tested in accordance with the standard GB / T2567-2021;

[0101] The elongation at break was tested in accordance with the standard GB / T2567-2021;

[0102] Bending strength was tested in accordance with standard GB / T2567-2021;

[0103] The flexural modulus of elasticity was tested in accordance with standard GB / T2567-2021;

[0104] The heat distortion temperature was tested in accordance with the standard GB / T2567-2021.

[0105] Table 3 Performance test results of the examples and comparative examples

[0106] .

[0107] As shown in Table 3, the tensile strength of Examples 1-5 is 85.08-98.48 MPa, the tensile modulus of elasticity is 3623.0-3926.5 MPa, the elongation at break is 2.61-3.55%, the flexural strength is 132.1-138.8 MPa, the flexural modulus of elasticity is 3765.4-3920.3 MPa, and the heat distortion temperature is 133.6-139.3℃, which meets the requirements for optical cable reinforcing core materials. Adipic acid plays a role in improving toughness, while isophthalic acid mainly enhances strength and heat resistance. By regulating the molecular chain structure, a synergistic balance of high rigidity, heat resistance, and moderate toughness required for optical cable reinforcing cores is achieved. The flexural strength of Example 3 reaches 138.8 MPa, and the heat distortion temperature reaches 139.3℃.

[0108] The heat distortion temperature range of 133.6~139.3℃ in this application is because optical cables erected at high altitudes are subject to high temperatures from daytime sunlight, coupled with the heat generated during communication, leading to a rapid temperature increase. For optical cables facing underground burial and high-altitude installations (due to day / night / seasonal temperature differences), a heat distortion temperature of 133.6~139.3℃ helps prevent performance degradation caused by temperature changes. A heat distortion temperature that is too low will cause the resin to soften under high-temperature conditions, making it unable to maintain structural rigidity, resulting in cracks and loss of support; bending strength will decrease with increasing temperature, making it unable to withstand the cable's own weight, causing the overhead optical cable to sag and deform; a low heat distortion temperature will also cause cracks to accelerate the intrusion of moisture and contaminants, triggering resin hydrolysis or degradation, while increasing the difficulty of cable splicing and maintenance, and shortening its service life.

[0109] The results of Comparative Examples 1 and 2 show that when the alkyd-acid ratio exceeds the range of this application, esterification will be incomplete, the molecular chain crosslinking density will be insufficient, and the tensile strength and heat distortion temperature will be reduced. Only when the alkyd-acid ratio is within the range of this application can the optimal tensile strength and heat distortion temperature be obtained.

[0110] The results of Comparative Examples 3 and 4 show that when the activity exceeds the range of this application, the elongation at break and the heat distortion temperature will decrease; only when the activity is within the range of this application can the optimal elongation at break and the heat distortion temperature be obtained.

[0111] The excessive adipic acid in Comparative Example 5 led to a decrease in heat distortion temperature, and the excessive rigidity in Comparative Example 6 led to stress concentration and easy fracture. The results of Comparative Examples 5 and 6 show that only when the molar ratio of adipic acid to isophthalic acid is within the range of this application can toughness and heat resistance be balanced.

[0112] In Comparative Example 7, the simultaneous addition of isophthalic acid and adipic acid resulted in a decrease in both mechanical properties and heat distortion temperature. This is because the simultaneous addition of both leads to a slower synthesis rate and incomplete reaction. Therefore, it is evident that only by following the preparation steps of this application can the technical effects of this application be achieved.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An unsaturated polyester resin for the reinforcing core of an optical cable, characterized in that, By weight, it consists of the following components: 600-760 parts propylene glycol, 254.6-290.6 parts isophthalic acid, 0.26-1.45 parts catalyst, 553.6-692.7 parts maleic anhydride, 15.9-18.7 parts adipic acid, 0.038-0.046 parts primary polymerization inhibitor, 0.17-0.21 parts secondary polymerization inhibitor, 790-911 parts styrene, 0.034-0.041 parts tertiary polymerization inhibitor, and 0.34-0.41 parts antioxidant; the molar ratio of total alcohol to total acid is 1.08-1.12:1; the molar ratio of unsaturated acid to saturated acid is 3.4-3.8:1; and the molar ratio of adipic acid to isophthalic acid is 1:12-16. The preparation method includes the following steps: (1) Add propylene glycol, catalyst and isophthalic acid to the reaction vessel in parts by weight and mix well under the protection of inert gas; (2) Under the protection of an inert gas, the product obtained in step (1) is heated to 185~190℃ to react and produce water. After the water is produced, the temperature is maintained for 0.5~1h. Then, the temperature is increased to 200~205℃ at a rate of 15~18℃ / h to react until the acid value is 15~20mgKOH / g. After cooling to 135~140℃, the first polymerization inhibitor, maleic anhydride and adipic acid are added in sequence according to the weight parts. After the water is produced, the temperature is increased to 165~170℃ to react and produce water. After the water is produced, the temperature is maintained for 0.5~1h. Then, the temperature is increased to 205~210℃ at a rate of 15~18℃ / h to react until the acid value is 10~15mgKOH / g. (3) After cooling the product obtained in step (2) to 150~160℃, add the second polymerization inhibitor according to the weight parts; (4) After cooling the product obtained in step (3) to 120~130℃, add styrene, third polymerization inhibitor and antioxidant according to the weight, mix well, and then cool down to ≤60℃ to obtain unsaturated polyester resin for optical cable reinforcing core.

2. The unsaturated polyester resin for optical cable reinforcing core according to claim 1, characterized in that, The first, second, and third polymerization inhibitors are at least one of methylhydroquinone, hydroquinone, and copper naphthenate.

3. The unsaturated polyester resin for optical cable reinforcing core according to claim 1, characterized in that, By weight, it consists of the following components: 640-720 parts propylene glycol, 264.6-282.6 parts isophthalic acid, 0.53-1.13 parts catalyst, 553.6-692.7 parts maleic anhydride, 15.9-18.7 parts adipic acid, 0.038-0.046 parts primary polymerization inhibitor, 0.17-0.21 parts secondary polymerization inhibitor, 790-911 parts styrene, 0.034-0.041 parts tertiary polymerization inhibitor, and 0.34-0.41 parts antioxidant.

4. The unsaturated polyester resin for optical cable reinforcing core according to claim 1, characterized in that: The molar ratio of total alcohol to total acid is 1.09 to 1.11:

1.

5. The unsaturated polyester resin for optical cable reinforcing core according to claim 1, characterized in that, The molar ratio of the unsaturated acid to the saturated acid is 3.5~3.7:

1.

6. The unsaturated polyester resin for optical cable reinforcing core according to claim 1, characterized in that, The molar ratio of adipic acid to isophthalic acid is 1:13~15.