A resin for double-wall tank and preparation method thereof

Abstract

The present invention particularly relates to a double-wall tank resin and a preparation method thereof. According to weight parts, the raw materials include at least: 85-120 parts of polyols, 35-76 parts of aromatic dicarboxylic acids, and 70-132 parts of dicarboxylic acid shrinkage products. The double-wall tank resin of the present application is specially developed for gas station oil tanks (SF / FF / liner modification), has excellent oil corrosion resistance, groundwater corrosion resistance, temperature change resistance, excellent comprehensive performance, and has passed UL1316 and UL1746 certifications, and has broad application prospects in the field of double-wall tank resins.

Description

Technical Field

[0001] The invention relates to the technical field of IPC C08, and in particular to a resin for a double-walled tank and a preparation method thereof. Background Art

[0002] The pollution of groundwater by underground oil tank leakage has become a global environmental crisis, and the treatment of contaminated soil is very difficult. With the release of the "Action Plan for Water Pollution Prevention and Control", the environmental protection of groundwater and soil has been strengthened. The corrosion and rupture of single-layer steel underground gasoline storage tanks and pipelines can easily cause serious groundwater pollution. Therefore, new underground refueling tanks must use safer SF and FF double-wall tanks. In this context, the market size of double-wall tank resins has expanded rapidly, but based on the special application scenarios of double-wall tanks, higher requirements are also placed on the performance of resins.

[0003] Chinese patent CN109912953 discloses a method for preparing a terephthalic acid type unsaturated polyester resin, using dicyclopentadiene, maleic anhydride, terephthalic acid, propylene glycol, diethylene glycol, hydroquinone, tungsten hexachloride and other raw materials to react to generate polyester resin, the obtained product has good wettability with glass fiber, and its casting body can be applied to S / F double-wall tank resin. However, the resin gel time of the prior art is relatively long, and the dicyclopentadiene and tungsten catalyst raw materials used are harmful to the human body, and are inflammable and explosive, and are difficult to popularize in practical application. Chinese patent CN111892702 discloses a method for preparing a terephthalic acid type unsaturated polyester resin and a method for preparing the same, using terephthalic acid and methyl propylene glycol, trimethylolpropane, antioxidant and other raw materials to react, and the dibasic acid only uses terephthalic acid, that is, a polyester resin with good transparency and high mechanical strength is obtained. However, the existing technology aims to optimize the reactivity of terephthalic acid during the synthesis process and inhibit the delamination of polyester. The resulting polyester resin is mainly used in SMC / BMC molding materials, but its corrosion resistance is limited and cannot meet the use requirements of underground oil storage tanks with more stringent use environments. Summary of the invention

[0004] In order to solve the above problems, the first aspect of the present invention provides a resin for double-walled tanks, wherein the raw materials thereof at least include, by weight: 85-120 parts of polyol, 35-76 parts of aromatic dicarboxylic acid, and 70-132 parts of dicarboxylic acid shrinkage product.

[0005] With the rapid development of the transportation industry and the national economy, the number of gas stations and oil storage containers (oil tanks) has increased sharply. Oil tanks have been buried underground for a long time, and are subject to erosion by underground water vapor and electrolytic corrosion, which makes it very easy to cause oil leakage accidents. Since 2015, the "Water Pollution Prevention and Control Action Plan" has been issued, stipulating that all underground oil tanks at gas stations must be updated to double-layer tanks or complete the installation of seepage pools before the end of 2017. However, in actual application, the existing double-wall tanks still cannot meet the corrosion resistance requirements of the harsh underground environment, and it is difficult to pass the certification of industry standards UL1316 and UL1746 (special test for double-wall tanks in UL laboratories in the United States). In response to this problem, the present application provides a resin for double-wall tanks, which adopts specific polyols, aromatic dicarboxylic acids, and dicarboxylic acid shrinkage products in combination with auxiliary agents to obtain a terephthalate resin, which can be applied to the inner lining of a double-wall tank to form an airtight coating protection, thereby significantly optimizing the corrosion resistance, water vapor resistance, and temperature resistance of the double-wall tank. On the one hand, it improves the safety of the oil storage container and extends the service life of the oil tank. On the other hand, it avoids large-scale pollution to the environment caused by oil leakage. It has positive significance for the technological update of the field of resins for double-wall tanks.

[0006] In some preferred embodiments, the polyol is specifically an aliphatic polyol, and the aliphatic polyol has 0-4 methyl branches in its structure.

[0007] In some preferred embodiments, the aliphatic polyol has a melting point of -100 to 140°C, a surface tension of 30 to 44 dyne / cm, and a molecular weight of 65 to 154.

[0008] As an example of the above-mentioned aliphatic polyol, for example, propylene glycol; the melting point of propylene glycol is -60°C, the surface tension is 38 dyne / cm, and the molecular weight is 76.1.

[0009] As an example of the above-mentioned aliphatic polyol, for example, methyl propylene glycol; the melting point of methyl propylene glycol is -91°C, the surface tension is 37 dyne / cm, and the molecular weight is 90.1.

[0010] As an example of the above-mentioned aliphatic polyol, for example, dipropylene glycol; the melting point of the dipropylene glycol is -40°C, the surface tension is 32 dyne / cm, and the molecular weight is 134.2.

[0011] As an example of the above-mentioned aliphatic polyol, for example, neopentyl glycol; the melting point of the neopentyl glycol is 127° C., the surface tension is 36 dyne / cm, and the molecular weight is 104.2.

[0012] In some preferred embodiments, the aromatic dicarboxylic acid includes a combination of one or more of terephthalic acid, phthalic acid, and isophthalic acid; terephthalic acid is more preferred.

[0013] In some preferred embodiments, the dibasic acid shrinkage product includes one or more of maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and methylnadic anhydride.

[0014] In some preferred embodiments, the raw material of the double-wall tank resin further includes 186-230 parts of a cross-linking agent.

[0015] More preferably, the crosslinking agent includes a combination of one or more of styrene, 2-phenylpropylene, and 4-methylstyrene.

[0016] In some preferred embodiments, the raw material of the double-wall tank resin further includes 0.01-1 part of a polymerization inhibitor.

[0017] In some preferred embodiments, the polymerization inhibitor is selected from phenolic polymerization inhibitors and / or quinone polymerization inhibitors.

[0018] In some preferred embodiments, the polymerization inhibitor includes a first polymerization inhibitor and a second polymerization inhibitor, and both the first polymerization inhibitor and the second polymerization inhibitor are phenolic polymerization inhibitors.

[0019] More preferably, the phenolic polymerization inhibitor includes one or more of hydroquinone, 2-methylhydroquinone, 2-tert-butylhydroquinone, p-hydroxyanisole, and 2,5-di-tert-butylhydroquinone.

[0020] More preferably, the first polymerization inhibitor is methyl hydroquinone, and the second polymerization inhibitor is hydroquinone.

[0021] After a lot of experimental research, the present application found that the intermediate material obtained by reacting aliphatic polyols with a melting point of -100 to 140°C, a surface tension of 30 to 44 dyne / cm, and a molecular weight of 65 to 154 with polyacids and dibasic acid shrinkage products can react with a crosslinking agent to generate a high crosslinking density terephthalic resin. In particular, the polycondensation product obtained by using small molecular weight branched aliphatic polyols in combination with terephthalic acid and maleic anhydride has suitable reaction activity, and the linear molecules produce orderly chemical bond linkage under the coordination of styrene to form a stable three-dimensional spatial network structure, which can give the resin better processing performance, and the obtained resin has excellent oil corrosion resistance and groundwater corrosion resistance. At the same time, it was unexpectedly discovered that by adding inhibitors in batches and controlling the first inhibitor to be hydroquinone and the second inhibitor to be methyl hydroquinone, a suitable induction period can be provided for the polymerization process, so that the molecular structure of the resin can be effectively regulated, and the resin product finally formed has excellent temperature resistance. After actual testing and verification, the double-wall tank resin of the present application has extremely strong temperature resistance and can provide applicability in all seasons from extreme cold (winter: below 7°C) to high temperature (summer: 25 degrees Celsius).

[0022] A second aspect of the present invention provides a method for preparing a double-walled tank resin, the preparation steps of the double-walled tank resin comprising:

[0023] S1. According to the formula, add aromatic dicarboxylic acid and polyol to the reactor in sequence, stir and heat to 170-185°C under nitrogen protection, then heat to 180-230°C at a rate of 0.1-0.5°C / min, and keep warm until the acid value of the material is ≤8mgKOH / g to obtain intermediate material A;

[0024] S2. The intermediate material A is cooled to below 100°C, and the olefinic acid shrinkage product and the first inhibitor are sequentially added to the reactor, the temperature is raised to 150-165°C, and then the temperature is raised to 180-230°C at a rate of 0.1-0.5°C / min, and the temperature is maintained and stirred with nitrogen until the acid value is 20-35mgKOH / g to obtain the intermediate material B;

[0025] S3. Cool down to 150-165°C, add the crosslinking agent and the second polymerization inhibitor to the intermediate material B, continue to cool to 40-70°C, stir for 0.5-2h, and obtain the finished resin for double-wall tank.

[0026] The double-wall tank resin prepared by the above-mentioned formula and process has excellent construction performance, can meet the mechanical strength requirements of the spraying process, winding process, and hand lay-up process at the same time, and the viscosity and gel time of the obtained liquid resin are controllable, and the processability is good. Furthermore, the HDT (heat deformation temperature) of the resin casting can reach 128°C, and the cured product has excellent acid resistance, salt resistance, and polar solvent resistance, and has the advantages of high rigidity and not easy to deform. The high cross-linked double-wall tank resin provides reliable corrosion resistance, anti-penetration and dense protection for the storage tank, and the resin has excellent comprehensive performance.

[0027] The third aspect of the present invention provides use of the resin described above in a double-walled tank.

[0028] Beneficial effects:

[0029] The double-wall tank resin provided in this application has the following advantages:

[0030] (1) The high cross-link density paraben resin obtained through specific raw materials and processes has excellent corrosion resistance and can effectively resist the erosion of acidic, alkaline and polar solvents, providing a dense protective barrier for double-wall tanks, which greatly inhibits the corrosion of double-wall tanks by environmental media when they are buried deep underground, and avoids oil leakage and environmental pollution;

[0031] (2) The obtained resin has strong temperature resistance and can maintain good mechanical and chemical stability under various temperature changes. It can effectively play a protective role in spring and autumn (15-25°C), summer (above 25°C), winter (below 15°C), and especially in severe winter (below 7°C);

[0032] (3) The obtained resin has excellent mechanical properties, the casting has high rigidity and dimensional stability, strong pressure bearing capacity, and excellent heat resistance, with HDT reaching 128°C;

[0033] (4) The resin provided in this application is specially developed for gas station oil tanks (SF / FF / lining modification), has excellent resistance to oil corrosion, groundwater corrosion, temperature change, excellent comprehensive performance, and has passed UL1316 and UL1746 certification. It has broad application prospects in the field of double-wall tank resins. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1-2. UL1316 certification certificate of the resin for double-walled tanks provided in Example 1. DETAILED DESCRIPTION

[0035] Example 1.

[0036] The present embodiment provides a resin for double-walled tanks. A resin for double-walled tanks, the raw materials of which include, by weight: 100 parts of polyol, 55 parts of aromatic dicarboxylic acid, 110 parts of dicarboxylic acid shrinkage product, 200 parts of cross-linking agent, and 0.1 part of inhibitor.

[0037] The polyol is specifically an aliphatic polyol, specifically methyl propanediol, propylene glycol, dipropylene glycol and neopentyl glycol in a weight ratio of 3:1:2:1.5.

[0038] The propylene glycol has a melting point of -60°C, a surface tension of 38 dyne / cm, and a molecular weight of 76.1.

[0039] The methyl propylene glycol has a melting point of -91°C, a surface tension of 37 dyne / cm, and a molecular weight of 90.1.

[0040] The dipropylene glycol has a melting point of -40°C, a surface tension of 32 dyne / cm, and a molecular weight of 134.2.

[0041] The neopentyl glycol has a melting point of 127° C., a surface tension of 36 dyne / cm, and a molecular weight of 104.2.

[0042] The aromatic dicarboxylic acid is terephthalic acid.

[0043] The dibasic acid shrinkage product is maleic anhydride, and its CAS number is 108-31-6.

[0044] The crosslinking agent is styrene.

[0045] The polymerization inhibitor specifically comprises a first polymerization inhibitor and a second polymerization inhibitor in a weight ratio of 1:1.

[0046] The first polymerization inhibitor is methyl hydroquinone, and the second polymerization inhibitor is hydroquinone.

[0047] The preparation steps of the double-wall tank resin include:

[0048] S1. According to the formula, aromatic dicarboxylic acid and polyol were added to the reactor in sequence, and the temperature was raised to 180°C under nitrogen protection with stirring, and then raised to 210°C at a rate of 0.2°C / min, and kept warm until the acid value of the material reached 4±4mgKOH / g to obtain intermediate material A;

[0049] S2. The intermediate material A was cooled to 95°C, and the olefinic acid shrinkage product and the first inhibitor were added to the reactor in sequence, and the temperature was raised to 160°C, and then raised to 210°C at a rate of 0.2°C / min, and the temperature was kept warm and stirred with nitrogen until the acid value was 27±3mgKOH / g to obtain the intermediate material B;

[0050] S3. Cool down to 160°C, add the crosslinking agent and the second polymerization inhibitor to the intermediate material B, continue to cool to 60°C, stir for 1 hour, and obtain the finished resin for double-wall tanks.

[0051] Note: The double-wall tank resin provided in Example 1 of the present invention is the EL-8300 product of Zhenjiang Lidel Composite Materials Co., Ltd.

[0052] Performance Testing

[0053] 1. Resin technical indicators

[0054] The double-wall tank resin provided in Example 1 was tested for technical indicators, and the results are recorded in Table 1.

[0055] The gel time is specifically measured in a 25° C. water bath with a curing agent (Butanox M-50, the amount of which is 1% of the resin mass) added.

[0056] Table 1.

[0057]

[0058]

[0059] 2. Mechanical properties

[0060] The double-wall tank resin provided in Example 1 was placed at room temperature for curing for 24 hours to obtain a casting, and the mechanical properties were tested. The results are recorded in Table 2.

[0061] Table 2.

[0062] project Numeric unit Test Standards Tensile Strength 62 MPa GB / T2567 Tensile modulus 3100 MPa GB / T2567 Elongation at break 3 ％ GB / T2567 Bending Strength 110 MPa GB / T2567 Flexural modulus 3300 MPa GB / T2567 Impact strength 15 KJ / m2 GB / T1043.1 HDT 128 ℃ GB / T1634.1

Claims

1. A resin for double-walled tanks, characterized in that: The raw materials include, by weight: 100 parts of polyol, 55 parts of aromatic dicarboxylic acid, 110 parts of dicarboxylic acid shrinkage product, 200 parts of crosslinking agent, and 0.1 parts of inhibitor; The polyol is specifically an aliphatic polyol, specifically methyl propanediol, propylene glycol, dipropylene glycol and neopentyl glycol in a weight ratio of 3:1:2:1.5; The aromatic dicarboxylic acid is terephthalic acid; The dibasic acid shrinkage product is maleic anhydride, CAS No. 108-31-6; The cross-linking agent is styrene; The polymerization inhibitor is specifically a first polymerization inhibitor and a second polymerization inhibitor in a weight ratio of 1:1; The first polymerization inhibitor is methyl hydroquinone, and the second polymerization inhibitor is hydroquinone; The preparation steps of the double-wall tank resin include: S1. According to the formula, aromatic dicarboxylic acid and polyol were added to the reactor in sequence, and the temperature was raised to 180°C under nitrogen protection with stirring, and then raised to 210°C at a rate of 0.2°C / min, and kept warm until the acid value of the material reached 4±4mgKOH / g to obtain intermediate material A; S2. The intermediate material A is cooled to 95°C, and the dibasic acid shrinkage product and the first polymerization inhibitor are added to the reactor in sequence, and the temperature is raised to 160°C, and then raised to 210°C at a rate of 0.2°C / min, and the temperature is maintained and stirred with nitrogen until the acid value is 27±3mgKOH / g, to obtain the intermediate material B; S3. Cool down to 160°C, add the crosslinking agent and the second polymerization inhibitor to the intermediate material B, continue to cool down to 60°C, stir for 1 hour, and obtain the finished resin for double-wall tank.

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