Low-volatility phosphate ester compositions for flame-retardant flexible PVC

Abstract

The present invention: a) 0 to 30% by weight of (RO)3P=O, b) 10 to 90% by weight of (RO)2(PhO)P=O; c) 10 to 90% by weight of (RO)(PhO)2P=O, and d) 0 to 0.5 wt% of (PhO)3P=O (Each percentage is based on the total weight of components a) to d). where R is a group JPEG2026508575000007.jpg33170, and Ph corresponds to a phenyl group, the mixture exhibits a unique combination of low volatility, high flame retardancy, and low melting or softening temperatures. The mixture is therefore particularly suitable for use as a flame retardant in PVC compounds, as a hydraulic fluid, as a lubricant additive, or as an additive for paints, adhesives, sealants, or coatings.

Description

[Technical Field]

[0001] Phosphate esters can be used in various technical applications, for example as lubricants (see WO 02 / 04999), as hydraulic fluids (see WO 02 / 04999), as plasticizers (see WO 02 / 04999), or as flame retardants (see WO 02 / 04999). [Background technology]

[0002] The flame retardant effect of phosphate esters has already been demonstrated in various plastics, such as PVC (see Patent Document 5), polyolefins (see Patent Document 6), cellulose esters (see Patent Document 7), polyurethanes (see Patent Document 4), or styrene polymers (see Patent Document 8).

[0003] Phosphate esters are particularly important in the processing of flexible PVC, where they act as both flame retardants and plasticizers. Mixed alkylaryl phosphate esters are frequently used here. An example is 2-ethylhexyl-diphenyl phosphate, known from US Pat. No. 5,623,499 and sold commercially as Disflamoll® DPO.

[0004] However, mixed alkylaryl phosphates have the disadvantage of being less flame-retardant than triaryl phosphates and being highly volatile, leading to loss of plasticizer and therefore to undesirable gradual embrittlement over the service life of flexible PVC articles.

[0005] Furthermore, prior art alkylaryl phosphate esters such as Disflamoll® DPO contain 1% to 5% by weight of triphenyl phosphate, which, due to its harmful properties, is desired to be even lower in content in consumer applications.

[0006] Therefore, many attempts have been made to find improved alkylaryl phosphate esters. For example, a phosphoric acid ester based on 2-phenoxyethanol and phenol is known from (Non-Patent Document 1). The product is described as a phosphoric acid ester composition, but its constituents or their quantitative ratios are not disclosed. There is also no information on the triphenyl phosphate content or the volatility of the product.

[0007] When the preparation of phosphate esters based on 2-phenoxyethanol and phenol according to (Non-Patent Document 1) was reexamined, it was found that the triphenyl phosphate content was high and the volatility also left room for improvement. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] US Patent No. 10,414,964 B2 [Patent Document 2] US Patent No. 6,703,355 B2 [Patent Document 3] German Patent No. 1 768 076 [Patent Document 4] US Patent No. 8,129,457 B2 [Patent Document 5] British Patent No. 2 302 543 A [Patent Document 6] US Patent No. 11,008,440 B2 [Patent Document 7] US Patent No. 9,000,148 B2 [Patent Document 8] US Patent No. 8,026,303 B2 [Patent Document 9] European Patent No. 0 000 240 A1 [Non-patent literature]

[0009] [Non-Patent Document 1] RTGottesman et al.,Fire Retardants,Proc.Int.Symp.Flammability Fire Retardants 1976,225-237 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention therefore aims to provide a mixture characterized by low volatility and a low triphenyl phosphate content, which achieves a high flame retardant effect, especially when combined with PVC molding compounds. Preferably, the mixture should have a low melting point and ideally be in liquid form at room temperature, which facilitates processing. Preferably, the mixture should also be obtainable with a low triphenyl phosphate content through a simpler process. In addition, a plasticizing effect in PVC should be achieved. [Means for solving the problem]

[0011] The objectives are: a) 0% to 30% by weight of (RO)3P=O; b) 10% to 90% by weight of (RO)2(PhO)P=O; c) 10% to 90% by weight of (RO)(PhO)2P=O and d) 0% to 0.5% by weight of (PhO)3P=O (Each percentage is based on the total weight of components a) to d), preferably, each percentage is based on the total weight of the mixture.) This is achieved by a mixture comprising where R is a group [ka] and and Ph corresponds to a phenyl group. DETAILED DESCRIPTION OF THE INVENTION

[0012] In a preferred embodiment of the present invention, the mixture a) 1% to 30% by weight of (RO)3P=O; b) 20% to 84% by weight of (RO)2(PhO)P=O; c) 15% to 79% by weight of (RO)(PhO)2P=O, and d) 0% to 0.5% by weight of (PhO)3P=O (Each percentage is based on the total weight of components a) to d), preferably, each percentage is based on the total weight of the mixture.) Includes.

[0013] In a further preferred embodiment of the present invention, the mixture comprises a) 5% to 30% by weight of (RO)3P=O; b) 20% to 80% by weight of (RO)2(PhO)P=O; c) 15% to 75% by weight of (RO)(PhO)2P=O, and d) 0% to 0.2% by weight of (PhO)3P=O (Each percentage is based on the total weight of components a) to d), preferably, each percentage is based on the total weight of the mixture.) Includes.

[0014] In a further preferred embodiment of the present invention, the mixture comprises a) 10% to 25% by weight of (RO)3P=O, b) 50% to 75% by weight of (RO)2(PhO)P=O; c) 15% to 40% by weight of (RO)(PhO)2P=O, and d) 0% to 0.2% by weight of (PhO)3P=O (Each percentage is based on the total weight of components a) to d), preferably, each percentage is based on the total weight of the mixture.) Includes.

[0015] In a particularly preferred embodiment of the invention, the phosphate ester composition according to the invention comprises less than 0.2% by weight of triphenyl phosphate, particularly preferably less than 0.1% by weight of triphenyl phosphate.

[0016] Preferably, the mixture according to the invention is present as a solid or liquid at 23°C and 1013 mbar, particularly preferably as a liquid with a dynamic viscosity of 20 to 5000 mPa·s, most preferably 50 to 2000 mPa·s (in each case at 23°C).

[0017] Preferably, the mixtures according to the invention have a melting or softening point of less than 70°C, preferably less than 55°C, particularly preferably less than 40°C.

[0018] Preferably, the mixture according to the invention has an acid number of less than 5 mg KOH / g, preferably less than 1 mg KOH / g, particularly preferably less than 0.3 mg KOH / g, very particularly preferably less than 0.1 mg KOH / g.

[0019] It has been found, surprisingly, that PVC molding compounds containing the mixtures according to the invention have high flame retardancy.The mixtures according to the invention can be prepared unexpectedly easily by a novel process, so that they contain no or only very little triphenyl phosphate.

[0020] The present invention further comprises: (a) providing a mixture comprising phosphorus oxychloride and phenoxyethanol; (b) reacting at least a portion of the mixture from a) while removing hydrogen chloride at a temperature between 0°C and 50°C. (c) providing a mixture comprising a phenol and a base, and optionally a solvent; (d) combining the mixture obtained in b) with the mixture from c) and reacting at a temperature between −20° C. and 50° C. to form the chloride salt. The present invention provides a process for preparing the mixture of the present invention, comprising:

[0021] In an alternative embodiment, at least a portion of the phosphorus oxychloride is metered only in step b). It is also possible to meter at least a portion of the phenoxyethanol only in step b).

[0022] The reaction in step b) is usually carried out at a temperature within the range of 0 to 50°C, preferably within the range of 10 to 40°C, and particularly preferably within the range of 20 to 30°C.

[0023] Optionally, distillative removal of (unreacted) reactants from step a) and / or by-products formed (such as hydrogen chloride) may be carried out between steps b) and c). The distillation can be carried out as a batch process or as a continuous process. The temperature of the distillation is preferably in the range of 0°C to 50°C. Particularly preferably, the distillation is carried out at the reaction temperature of step b) or at a temperature between 0°C and the reaction temperature of step b). The distillation is carried out at a pressure in the range of 0.01 mbar to 1013 mbar, preferably in the range of 0.01 mbar to 100 mbar, very particularly preferably in the range of 0.01 mbar to 50 mbar.

[0024] Any commercially available base known to those skilled in the art can be used as the base for step c), including alkali metal hydroxides such as NaOH, KOH or LiOH, or amines such as triethylamine, imidazole, 1-methylimidazole, diisopropylethylamine, dibutylamine, morpholine, etc., including ammonia or ammonia solution.

[0025] In a preferred embodiment, a solvent is used for the reaction in step c).All commercially available solvents known to those skilled in the art can be used as the solvent.These include, for example, water, aromatic hydrocarbons such as toluene, xylene, aliphatic hydrocarbons such as pentane, hexane, cyclohexane, heptane or longer chain hydrocarbons, or chlorinated hydrocarbons such as dichloromethane, dichloroethane or chlorobenzene.

[0026] In an alternative embodiment, at least a portion of the mixture resulting in step c) is metered into the mixture obtained in step b). It is also possible to meter at least a portion of the base or a portion of the phenol only in step d).

[0027] The reaction in step d) is usually carried out at a temperature in the range of -20°C to 50°C, preferably in the range of 0°C to 30°C.

[0028] Removal of reactants and / or by-products from steps b) and / or d) may be carried out after step d) by filtration, extraction, washing and / or distillation. In a preferred embodiment of the present invention, chloride salts formed as by-products are first removed. If water is used as an optional solvent in step c), removal can be carried out by simply separating the aqueous and organic phases. If step c) is carried out without water, chloride salts can be removed by filtration.

[0029] For further purification, the product may be subjected to washing. Suitable washing solutions are, for example, sodium hydroxide solution or potassium hydroxide solution or water. Washing is usually carried out at a temperature of 20°C to 50°C.

[0030] The solvent optionally used in step c) can be removed by distillation, the conditions for which can be readily determined by one skilled in the art.

[0031] Depending on application, the mixture of the present invention can also comprise other auxiliaries.The examples of suitable auxiliaries are plasticizer, plasticizing polymer, polymer modifier, stabilizer (for example, heat stabilizer, light stabilizer, antioxidant), co-stabilizer (for example, acid scavenger, free radical scavenger), internal and external lubricant, viscosity adjuster, filler, color pigment, dye, flame retardant, flame retardant synergist, expansion agent, and further functional additives such as antistatic agent, nucleating agent, UV protectant or biocide (see, for example, RD Maier, M.Schiller, Handbuch Kunststoff-Additive [Plastics Additives Handbook], 4th edition, Munich, Carl Hanser Verlag, 2016, p.513 ff.).

[0032] The mixtures according to the invention are suitable as flame retardants. The invention therefore further provides the use of the mixtures according to the invention as flame retardants.

[0033] The mixtures according to the invention can be used as flame retardants in all applications of flame retardants known to those skilled in the art. Preferably, the mixtures according to the invention are - synthetic polymers such as polyolefins, polyvinyl chloride, polycarbonate, styrenic (co)polymers, polyamides, polyesters, polyurethanes, elastomers such as NBR, CR, SBR or EPDM, and thermosetting resins such as epoxy resins, unsaturated polyester resins and phenol formaldehyde resins; - Plant-based materials such as wood, wood-plastic composites, paper and cardboard, and -Animal-derived materials such as leather It is used as a flame retardant for

[0034] It is particularly preferred to use the mixtures according to the invention as flame retardants for polyvinyl chloride (PVC), for example in PVC moulding compounds, i.e. in compositions comprising PVC in the form of granules, powder, paste or plastisol.

[0035] The present invention therefore also provides compositions comprising the mixtures according to the invention and polyvinyl chloride (PVC), preferably in the form of granules, powder, paste or plastisol. These PVC molding compounds according to the invention are preferably flexible PVC. The PVC molding compounds according to the invention can be produced by mixing and compounding PVC with the mixtures according to the invention, optionally with further auxiliaries such as stabilizers, in a known manner (see, for example, G. Becker, D. Braun, Kunststoff-Handbuch, Polyvinylchlorid [Plastics Handbook, Polyvinyl Chloride], Vol. 2 / 2, Munich, Vienna, Carl Hanser Verlag, 1986, p. 829 ff.), or by dispersing them to form a ready-to-process plastisol or organosol.

[0036] The PVC moulding compounds according to the invention preferably contain 5 to 150 parts by weight, particularly preferably 30 to 70 parts by weight, of the phosphate esters according to the invention (RO)3P=O, (RO)2(PhO)P=O, (RO)(PhO)2P=O and (PhO)3P=O as defined above, based on 100 parts by weight of PVC. In a preferred embodiment, the PVC moulding compounds according to the invention contain 5 to 150 parts by weight, particularly preferably 30 to 70 parts by weight, of the phosphate esters according to the invention, based on 100 parts by weight of PVC.

[0037] The PVC molding compounds according to the invention can be used in coatings, films, cables, pipelines, hoses, seals, conveyor belts, roofing membranes, adhesive tape films, tarpaulins, awnings and tents.

[0038] The present invention further provides the use of the mixture according to the invention in a working fluid or for the production of a working fluid. Preferably, the mixture according to the invention is used in a fire-retardant working fluid.

[0039] The present invention further provides the use of the mixture according to the invention as a lubricant additive. Preferably, the mixture according to the invention is used in a fire-retardant lubricant.

[0040] The present invention further provides the use of the mixture according to the invention as an additive for paints, adhesives, sealants and coatings.

[0041] The present invention further provides the use of the mixture according to the present invention as a heat transfer medium or in a preparation for use as a heat transfer medium. Preferably, the mixture according to the present invention is used as a heat transfer medium or in a heat transfer medium preparation for immersion cooling of electrical components. In addition to the mixture according to the present invention, the heat transfer medium preparation contains, for example, further trialkyl phosphates, triaryl phosphates, mineral oils, polyalphaolefins, esters, antioxidants, metal deactivators, flow improvers, corrosion inhibitors, antifoam agents, demulsifiers and / or pour point depressants. [Example]

[0042] Determination of the composition of phosphate ester compositions Quantitative GC-FID analysis was performed using an Agilent 7890A GC instrument equipped with a CB-Sil 5 CB quartz capillary column (length: 30 m, diameter: 0.32 mm, film thickness: 3.00 μm). The carrier gas used was hydrogen. The sample (dissolved in acetone) was injected in split mode (86:1) at a temperature of 300 °C. The following temperature program was set: starting temperature 60 °C, heating rate 10 °C / min to a temperature of 150 °C, then heating rate 25 °C / min to 280 °C, holding time: 10 min, then heating rate 25 °C / min to a final temperature of 320 °C / min, holding time: 10 min. Evaluation was performed by integration of the corresponding baseline separation signal and conversion of the peak area to content after prior calibration.

[0043] Determining the viscosity of phosphate ester compositions The dynamic viscosity of the phosphate ester is measured according to DIN 53018 at 200 s -1The shear rates were measured using an Anton Paar MCR 102 shear rheometer at the temperatures indicated.

[0044] Determination of Acid Value of Phosphate Ester Composition The acid value of the samples was determined according to DIN EN ISO 2114 (method B, colorimetric titration with phenolphthalein). For this purpose, a sample (10 g) was weighed, dissolved in acetone (200 ml) and water (50 ml), and mixed with 2-3 drops of phenolphthalein solution (0.1% by weight in ethanol / water (v / v = 4 / 1)). Sodium hydroxide solution (0.1 mol / l) was titrated from a burette until a color change from colorless to pink occurred under stirring and lasted for at least 10 seconds. A blank value was measured in the same way without the sample.

[0045] Synthesis Example Comparative Example 1 (V1) Prepared according to RTGottesman et al., Fire Retardants, Proc. Int. Symp. Flammability Fire Retardants 1976, 225-237.

[0046] Phosphorus oxychloride (200 parts by weight) was initially charged into a reactor equipped with a stirrer, internal thermometer, nitrogen inlet, and reflux condenser. Phenoxyethanol (182 parts by weight) was metered in. The resulting reaction product was reacted with a solution of sodium hydroxide (129 parts by weight), phenol (245 parts by weight), and water (600 parts by weight) to obtain a two-phase reaction mixture. After phase separation, the organic phase was washed with sodium hydroxide solution (0.5 mol / l; 500 parts by weight) and then with water (500 parts by weight). Volatile components were removed by distillation at 50°C and 20 mbar. The product mixture was isolated as a solid (melting point: 73°C). The acid number was 0.1 mg KOH / g. The phosphate ester compositions were 0.5 wt% (phenoxyethyl O)P=O, 13.7 wt% (phenoxyethyl O)(PhO)P=O, 84.8 wt% (phenoxyethyl O)(PhO)P=O, and 1.0 wt% (PhO)P=O ("TPP").

[0047] Synthesis Example 1 (S1) of the Present Invention Phosphorus oxychloride (200 parts by weight) was initially charged to a reactor equipped with a stirrer, internal thermometer, nitrogen inlet, and reflux condenser. Phenoxyethanol (271 parts by weight) was metered in so as to maintain the internal temperature between 20°C and 25°C. After the addition was complete, the pressure in the apparatus was gradually reduced from atmospheric pressure to 10 mbar and maintained under these conditions for 1 hour. The reaction mixture was metered in at 0°C to a mixture of dichloromethane (401 parts by weight), phenol (210 parts by weight), and triethylamine (251 parts by weight), while maintaining the internal temperature between 0°C and 15°C. The solids were removed by filtration, and the filtrate was washed three times with sodium hydroxide solution (2%, 500 parts by weight) and then three times with water (500 parts by weight). The solvent was removed by distillation at 90°C and 20 mbar. The product mixture was isolated as a solid (melting point: 54°C). The acid number was <0.1 mg KOH / g. The product mixture contained 5.3 wt% (phenoxyethyl O)3P=O, 43.1 wt% (phenoxyethyl O)2(PhO)P=O, 51.6 wt% (phenoxyethyl O)(PhO)2P=O, and <0.1 wt% (PhO)3P=O ("TPP").

[0048] Synthesis Example 2 (S2) of the Present Invention Phosphorus oxychloride (201 parts by weight) was initially charged to a reactor equipped with a stirrer, internal thermometer, nitrogen inlet, and reflux condenser. Phenoxyethanol (361 parts by weight) was metered in so as to maintain the internal temperature between 20°C and 25°C. After the addition was complete, the pressure in the apparatus was gradually reduced from atmospheric pressure to 10 mbar and maintained under these conditions for 1 hour. The reaction mixture was metered into a mixture of dichloromethane (401 parts by weight), phenol (186 parts by weight), and triethylamine (222 parts by weight) at 0°C, while maintaining the internal temperature between 0°C and 15°C. The solids were removed by filtration, and the filtrate was washed three times with sodium hydroxide solution (2%, 500 parts by weight) and then three times with water (500 parts by weight). The solvent was removed by distillation at 90°C and 20 mbar. The product mixture was isolated as a viscous liquid (330 mPa·s at 23°C). The acid number was <0.1 mg KOH / g. The product mixture contained 20.8 wt% (phenoxyethyl O)3P=O, 58.9 wt% (phenoxyethyl O)2(PhO)P=O, 20.3 wt% (phenoxyethyl O)(PhO)2P=O, and <0.1 wt% (PhO)3P=O ("TPP").

[0049] [Table 1]

[0050] Flexible PVC manufacturing The flexible PVC molding compounds used in the tests were produced in a laboratory rolling mill. After adding the mixture of all compounding ingredients (see Table 2), it was left on the rollers until a sheet was formed. Once the sheet was formed, the compound was compounded in the rolling mill for another 10 minutes and finally removed as a rolled sheet. The roll temperature was 165°C.

[0051] Test specimens for determining LOI were prepared from rolled sheets using a press. The press temperature was 170°C; the press time was 4 minutes for preheating at low pressure (<10 bar) and 2 minutes at high pressure (>100 bar). Test specimens with dimensions of 90 x 13 x 4 mm were cut from a 4 mm thick press plate.

[0052] The test specimens (50 x 40 x 6 mm) for determining the hardness of the compound were pressed for a longer time at the same temperature due to their thickness of 6 mm: 7 minutes for preheating at low pressure and 3 minutes for compression molding at high pressure.

[0053] [Table 2]

[0054] All of the phosphate ester formulations according to the invention were successfully used to produce flexible PVC. All samples were easily processable.

[0055] Flame retardancy, plasticizing effect and volatility evaluation The Limiting Oxygen Index (LOI) was used to assess flame retardancy. LOI is a measure of the burning behavior of plastics and other materials. It is the lowest oxygen concentration in a nitrogen / oxygen mixture at which combustion of a test specimen is sustainable under standard conditions. Tests were performed in accordance with ISO 4589-2.

[0056] The plasticizing effect of phosphate esters was determined using Shore A hardness measurements on phosphate ester-containing flexible PVC compounds. The measurement principle is based on the penetration depth of a metal test pin into a material sample with a force of 12.5 N for 15 seconds. Shore A hardness was measured on test specimens with dimensions of 50 x 40 x 6 mm. Shore A hardness measurements were performed in accordance with DIN ISO 7619-1. A Shore A hardness of less than 95 is considered an indicator of a plasticizing effect.

[0057] The volatility of the plasticizers was determined by thermogravimetric analysis (TGA) on a Mettler Toledo TGA / DSC3+ instrument, where the mass change due to evaporation of the sample as a function of temperature and time was measured. Individual samples (<20 mg) were weighed in open porcelain crucibles and heated from room temperature to 500 °C under a nitrogen atmosphere at a constant heating rate of 10 K / min. The mass loss of the individual products was measured at 245 °C.

[0058] The measurement results are summarized in Table 3.

[0059] [Table 3]

[0060] Surprisingly, the results show that the phosphate ester preparation according to the invention has a significantly lower volatility than the comparative example Disflamoll® DPO.

Claims

1. a) 0% to 30% by weight of (RO) ３ P=O, b) 10% to 90% by weight of (RO) ２ (PhO)P=O, c) 10% to 90% by weight of (RO)(PhO) ２ P=O, and d) 0% to 0.5% by weight of (PhO) ３ P=O (Each percentage is based on the total weight of components a) to d). where R is a group 【Chemistry 1】 and Ph corresponds to a phenyl group.

2. 2. The mixture of claim 1, containing less than 0.2% by weight of triphenyl phosphate, preferably less than 0.1% by weight of triphenyl phosphate.

3. 3. The mixture according to claim 1 or 2, which is present as a solid or liquid at 23°C and 1013 mbar, preferably as a liquid having a dynamic viscosity of 20 to 5000 mPa s, particularly preferably 50 to 2000 mPa s (in each case at 23°C).

4. 4. The mixture according to claim 3, which has a melting or softening point of less than 70°C, preferably less than 55°C, particularly preferably less than 40°C.

5. (a) providing a mixture comprising phosphorus oxychloride and phenoxyethanol; (b) reacting at least a portion of the mixture from a) while removing hydrogen chloride at a temperature between 0°C and 50°C. (c) providing a mixture comprising a phenol and a base, and optionally a solvent; (d) combining the mixture from b) with the mixture from c) and reacting at a temperature between −20° C. and 50° C. to form the chloride salt. A process for preparing the mixture of any one of claims 1 to 4, comprising:

6. 6. The process according to claim 5, wherein the base used in step c) is a trialkylamine, preferably triethylamine.

7. 7. The process according to claim 5 or 6, wherein distillative removal of reactants and / or by-products from step a) is carried out between steps b) and c).

8. 8. The process according to any one of claims 5 to 7, wherein the removal of reactants and / or by-products from steps b) and / or d) is carried out after step d), preferably by filtration, extraction, washing and / or distillation.

9. Use of a mixture according to any one of claims 1 to 4 as a flame retardant, preferably as a flame retardant for synthetic polymers, materials of plant origin or materials of animal origin.

10. 10. Use according to claim 9 as a flame retardant for polyvinyl chloride (PVC).

11. A molding compound comprising the mixture according to any one of claims 1 to 4 and polyvinyl chloride (PVC).

12. 12. Moulding compound according to claim 11, comprising 5 to 150 parts by weight, preferably 30 to 70 parts by weight, of said phosphoric acid esters a) to d), based on 100 parts by weight of PVC.

13. 11. Use of a molding compound according to claim 9 or 10 for the production of coatings, films, cables, pipelines, hoses, seals, conveyor belts, roof membranes, adhesive tape films, tarpaulins, awnings or tents.

14. Use of a mixture according to any one of claims 1 to 4 as a working fluid.

15. Use of the mixture according to any one of claims 1 to 4 as a lubricant additive.

16. 5. Use of a mixture according to any one of claims 1 to 4 as an additive for paints, adhesives, sealants or coatings.

17. Use of the mixture according to any one of claims 1 to 4 as a heat transfer medium.

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