Triphenyl phosphate-free mixtures for flame-retardant flexible PVC.

Abstract

The present invention relates to a compound represented by general formula (I) (R 1 O) n (R 2 O) o (R 3 O) p P=O(I) wherein n, o, and p can each be 0, 1, 2, or 3, and the sum of n, o, and p is 3, and R 1 , R 2 and R 3 is based JPEG2026507259000010.jpg30170) The mixtures exhibit a unique combination of low phosphorus content combined with high flame retardancy and plasticizing effect, such that they are suitable for use as flame retardants in PVC compounds, as hydraulic fluids, as lubricant additives, or as additives 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] The prior art describes various types of phosphoric acid esters and their use as flame retardants. These esters are composed of aromatic and / or aliphatic alcohols. Often, mixtures of different alcohols are used, resulting in mixtures of different ester combinations.

[0004] Compositions consisting of triaryl phosphate esters and / or alkylaryl phosphate esters have proven suitable for use as flame retardants in PVC. For economic and application-related reasons, the aryl groups in these products are always at least partially derived from phenol or cresol. In fact, the prior art even strongly recommends against using only highly substituted phenols (see, for example, Patent Document 9). This may be because the phosphate esters produced therefrom exhibit low flame retardant effectiveness due to their relatively low phosphorus content.

[0005] A drawback of phenol-based mixtures is their triphenyl phosphate ("TPP") content, which is inevitably present, at least in small amounts, as a result of their synthesis. Due to the harmful properties of this substance, triphenyl phosphate-containing materials are becoming less and less accepted for consumer use. The prior art therefore describes various processes for reducing the TPP content in mixtures.

[0006] For example, Patent Document 9 describes a two-step process in which phosphorus oxychloride is pre-reacted with a substoichiometric amount of alkylphenol before the resulting reaction mixture is completely reacted with phenol. However, the product thus prepared still contained at least 0.1 wt. % TPP. In addition, the additional process step adds complexity.

[0007] Patent Document 10 describes the purification of TPP-containing mixtures by distillation. However, the additional process step increases the production costs. In addition, the TPP content of the purified product still exceeds 1 wt. %.

[0008] Furthermore, the use of cresol-based mixtures is problematic from a toxicological and regulatory point of view, since ortho-cresyl phosphates have strong neurotoxic effects (see, for example, (Non-Patent Document 1)). The cresol fraction used for the preparation of phosphate esters must therefore be substantially ortho-cresol-free, which requires considerable technical complexity.

[0009] To overcome the aforementioned shortcomings of the prior art, phenol- and cresol-free alternatives are desirable.

[0010] There is a need for flame retardants that have a particularly low phosphorus content, as the production of phosphorus is both costly and energy intensive. [Prior art documents] [Patent documents]

[0011] [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] International Publication No. 2017140609 A1 Brochure [Patent Document 10] European Patent No. 0 573 082 B1 [Non-patent literature]

[0012] [Non-Patent Document 1] I. van der Veen, J. de Boer Chemosphere 2012,88,1119-1153 Summary of the Invention [Problem to be solved by the invention]

[0013] The object of the present invention was therefore to provide mixtures which are completely or substantially free of triphenyl phosphate and tricresyl phosphate as flame retardants for plastics, in particular PVC moulding compounds, and which have a lower phosphorus content but have comparable flame retardant effectiveness. [Means for solving the problem]

[0014] This object is achieved by the synthesis of compounds of general formula (I) (R 1 O) n (R 2 O) o (R 3 O) p P=O (I) wherein n, o, and p can each be 0, 1, 2, or 3, and the sum of n, o, and p is 3; and R 1 , R 2 and R 3 is independently [ka] is equivalent to DETAILED DESCRIPTION OF THE INVENTION

[0015] In a preferred embodiment, these two substances are 1 , R 2 or R 3 have at least one of the following in common, and two different groups are present in at least one of the two substances.

[0016] In a further embodiment, R 1 , R 2 and R 3 Mixtures of phosphate esters are used in which all four of the above groups according to formula (I) are present in the mixture (of course, each phosphorus atom is bonded to up to three different groups). However, mixtures containing up to three of these groups are preferred, and even more preferred are mixtures containing two of these groups.

[0017] Preferably, the mixture according to the invention comprises a compound of general formula (I) (R 1 O) n (R 2 O) o (R 3 O) p P=O (I) (wherein n=1, 2 or 3, o=0, 1 or 2, and p=0, where the sum of n and o is 3, and where R 1 and R 2 is independently [ka] equivalent to It contains at least two substances.

[0018] In a preferred embodiment, these two substances are 1 or R 2 and at least one of the two substances has two different groups R 1 or R 2 It has.

[0019] In a preferred embodiment, the triphenyl phosphate content and the tricresyl phosphate content, based on the total weight of the mixture, are in each case less than 1% by weight, preferably in each case less than 0.2% by weight, particularly preferably in each case less than 0.1% by weight, and most preferably in each case less than 0.01% by weight.

[0020] In a further preferred embodiment of the present invention, the mixture according to the present invention is 1 O)3P=O, (R 1 O)2(R 2 O)P=O, (R 1 O)(R 2 O)P=O, and (R 2 O)3P=O, and optionally a second component such as tert-butylphenol, thymol, guaiacol, phenoxyethanol, a catalyst component or by-product.

[0021] In a preferred embodiment, the mixtures according to the invention comprise in each case based on the total weight of the compounds of formula (I), preferably in each case based on the total weight of the mixture: (R 1 O)3P=O 0%~30wt% (R1 O)2(R 2 O)P=O 5%~90wt% (R 1 O)(R 2 O)2P=O 5%~90wt% (R 2 O)3P=O 0%~30wt% where R 1 and R 2 has the definition above.

[0022] 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 0.5 mg KOH / g.

[0023] Preferably, the mixture according to the invention has a phosphorus content of less than 8.0% by weight, preferably less than 7.5% by weight, more preferably less than 7.2% by weight, based on the total mass of phosphate esters present.

[0024] The mixtures according to the invention can be prepared analogously to known processes for the synthesis of phosphoric esters, as described, for example, in Methoden der Organischen Chemie [Methods of Organic Chemistry] (Houben-Weyl), Thieme-Verlag, Stuttgart 1964, Volume XII / 2, pp. 323 and 324.

[0025] The present invention therefore also relates to a process for the preparation of the mixture according to the invention, in which a compound of formula R 1 -OH, R 2 -OH and optionally R 3 The -OH phenol is reacted with POCl3 to form the compound of formula (I).

[0026] According to 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 other 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 et seq.).

[0027] Surprisingly, it has been found that the mixtures according to the invention are highly suitable for the production of flexible PVC and have a high flame retardant effect despite their low phosphorus content.

[0028] 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.

[0029] 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

[0030] 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.

[0031] 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, and 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 et seq.), or by dispersing them to form a ready-to-process plastisol or organosol.

[0032] The PVC molding compound according to the invention preferably contains 5 to 150 parts by weight, particularly preferably 30 to 70 parts by weight, of the phosphoric acid ester of formula (I) based on 100 parts by weight of PVC. In a preferred embodiment, the PVC molding compound according to the invention contains 5 to 150 parts by weight, particularly preferably 30 to 70 parts by weight, of the phosphoric acid ester of formula (I) based on 100 parts by weight of PVC.

[0033] The PVC molding compounds according to the invention can be used in coatings, films, cables, pipelines, hoses, seals, conveyor belts, roof membranes, adhesive tape films, tarpaulins, awnings and tents.

[0034] 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.

[0035] 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.

[0036] The present invention further provides the use of the mixture according to the invention as an additive for paints, adhesives, sealants and coatings.

[0037] 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]

[0038] General procedure for preparing the mixture according to the invention First, the phenol units are dissolved in dichloromethane in a reactor equipped with a stirrer, nitrogen inlet, internal thermometer, dropping funnel, and jacketed coil condenser. Triethylamine is added at room temperature under countercurrent nitrogen while stirring. After the addition is complete, the reaction mixture is cooled to 2-8°C and mixed with a solution of POCl3 in dichloromethane for 1-2 hours, not exceeding an internal temperature of 24°C. After the addition is complete, stirring is continued for another hour at room temperature. The reaction mixture is filtered, and the filter cake is washed with several portions of dichloromethane. The filtrate is washed with aqueous sodium hydroxide (2% by weight) and water at room temperature. The solvent and excess phenol units are then removed by distillation.

[0039] Synthesis Example 1 A mixture was prepared from POCl (200 parts by weight), thymol (305 parts by weight), p-tert-butylphenol (306 parts by weight), and triethylamine (441 parts by weight) in CHCl (440 parts by weight). The acid value was 0.4 mg KOH / g. The mixture contained 24.7 wt% (thymyl O)P=O, 19.5 wt% (thymyl O)(p-tert-butylphenyl O)P=O, 30.8 wt% (thymyl O)(p-tert-butylphenyl O)P=O, and 25.0 wt% (p-tert-butylphenyl O)P=O. The triphenyl phosphate and tricresyl phosphate contents were <0.01 wt% in each case.

[0040] Synthesis Example 2 A mixture was prepared from POCl (201 parts by weight), guaiacol (261 parts by weight), p-tert-butylphenol (314 parts by weight), and triethylamine (442 parts by weight) in CHCl (412 parts by weight). The acid value was 1.5 mg KOH / g. The mixture contained 11.8 wt% (guaiacyl O)P=O, 37.4 wt% (guaiacyl O)(p-tert-butylphenyl O)P=O, 38.0 wt% (guaiacyl O)(p-tert-butylphenyl O)P=O, and 12.8 wt% (p-tert-butylphenyl O)P=O. The triphenyl phosphate and tricresyl phosphate contents were <0.01 wt% in each case.

[0041] Synthesis Example 3 A mixture was prepared from POCl (200 parts by weight), guaiacol (257 parts by weight), thymol (307 parts by weight), and triethylamine (440 parts by weight) in CHCl (400 parts by weight). The acid value was 1.0 mg KOH / g. The mixture contained 20.0 wt% (guaiacyl O)P=O, 35.0 wt% (guaiacyl O)(thymyl O)P=O, 30.0 wt% (guaiacyl O)(thymyl O)P=O, and 15.0% (thymyl O)P=O. The triphenyl phosphate and tricresyl phosphate contents were <0.01 wt% in each case.

[0042] Synthesis Example 4 A mixture was prepared from POCl (202 parts by weight), phenoxyethanol (281 parts by weight), p-tert-butylphenol (306 parts by weight), and triethylamine (441 parts by weight) in CHCl (400 parts by weight). The acid value was 0.4 mg KOH / g. The mixture contained 10.0 wt% (phenoxyethyl O)P=O, 34.2 wt% (phenoxyethyl O)(p-tert-butylphenyl O)P=O, 39.6 wt% (phenoxyethyl O)(p-tert-butylphenyl O)P=O, and 16.2 wt% (p-tert-butylphenyl O)P=O. The triphenyl phosphate and tricresyl phosphate contents were <0.01 wt% in each case.

[0043] Synthesis Example 5 A mixture was prepared from POCl (201 parts by weight), phenoxyethanol (281 parts by weight), guaiacol (251 parts by weight), and triethylamine (440 parts by weight) in CHCl (400 parts by weight). The acid value was 0.4 mg KOH / g. The mixture contained 7.7 wt% (phenoxyethyl O)P=O, 37.2 wt% (phenoxyethyl O)(guaiacyl O)P=O, 44.4 wt% (phenoxyethyl O)(guaiacyl O)P=O, and 10.7 wt% (guaiacyl O)P=O. The triphenyl phosphate and tricresyl phosphate contents were <0.01 wt% in each case.

[0044] Synthesis Example 6 A mixture was prepared from POCl (200 parts by weight), phenoxyethanol (281 parts by weight), thymol (305 parts by weight), and triethylamine (403 parts by weight) in CHCl (407 parts by weight). The acid value was 0.6 mg KOH / g. The mixture contained 12.6 wt% (phenoxyethyl O)P=O, 41.7 wt% (phenoxyethyl O)(thymyl O)P=O, 34.6 wt% (phenoxyethyl O)(thymyl O)P=O, and 11.1 wt% (thymyl O)P=O. The triphenyl phosphate and tricresyl phosphate contents were <0.01 wt% in each case.

[0045] Determining the composition of a mixture 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.

[0046] The analytical data for Synthesis Examples S1 to S6 are again summarized in Table 1 .

[0047] [Table 1]

[0048] 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.

[0049] Comparative samples of known phosphate ester compositions Table 2 lists known phosphate ester compositions that were used as comparative samples in the production of flexible PVC. All comparative samples are products manufactured by Lanxess Deutschland GmbH.

[0050] [Table 2]

[0051] 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 3), 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.

[0052] 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.

[0053] [Table 3]

[0054] PVC samples were prepared according to this procedure.

[0055] Flame retardancy determination 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 measurement results are summarized in Tables 4 and 5.

[0057] [Table 4]

[0058] The results show that PVC compounds containing the known triaryl phosphate ester compositions Disflamoll® DPK, Disflamoll® 51092, and Reofos® 65 achieve LOI values ​​of 31.4 to 32.9 (Examples 1 to 3). The triaryl phosphate ester compositions S1, S2, and S3 according to the invention achieve values ​​within the same range despite having significantly lower phosphorus contents (Examples E1 to E3).

[0059] [Table 5]

[0060] The LOI values ​​of PVC compounds containing the mixed aryl / alkyl phosphate composition Disflamoll® DPO are significantly lower than those of the triaryl phosphate composition (27.4; Example V4). However, the mixed aryl / alkyl phosphate compositions S4, S5, or S6 according to the invention achieve higher LOI values ​​(27.8-27.9) than Disflamoll® DPO, despite their lower phosphorus content (Examples E4-E6).

[0061] All of the plasticizers listed in Tables 4 and 5 were suitable for making flexible PVC compounds.

[0062] Since the prior art describes a high phosphorus content in the mixture as a prerequisite for a high flame retardant effect (see, for example, WO2017140609 A1), it was surprising for a person skilled in the art that the triaryl phosphate ester composition according to the present invention, despite having a significantly lower phosphorus content, is able to achieve a flame retardant effect comparable to or even better than that of the corresponding class (triaryl phosphate esters or mixed aryl / alkyl phosphate esters).

Claims

1. General formula (I) (R １ O) ｎ (R ２ O) ｏ (R ３ O) ｐ P=O (I) wherein n, o, and p can each be 0, 1, 2, or 3, and the sum of n, o, and p is 3; and R １ , R ２ and R ３ is the base 【Chemistry 1】 (independently selected from A mixture containing at least two substances.

2. The two substances are １ , R ２ or R ３ 2. The mixture of claim 1, wherein the two substances have at least one of the following in common, and two different groups are present in at least one of the two substances.

3. The general formula (I) (R １ O) ｎ (R ２ O) ｏ (R ３ O) ｐ P=O (I) wherein n=1, 2, or 3, o=0, 1, or 2, and p=0, where the sum of n and o is 3, and where R １ and R ２ has the above definition, and preferably the two substances are １ or R ２ and at least one of the two substances has two different groups R １ or R ２ 3. The mixture of claim 1 or 2, wherein

4. 4. The mixture according to claim 1, wherein the content of triphenyl phosphate and the content of tricresyl phosphate are in each case less than 1% by weight, preferably in each case less than 0.2% by weight, particularly preferably in each case less than 0.1% by weight, and most preferably in each case less than 0.01% by weight, based on the total weight of the mixture.

5. in each case based on the total weight of compounds (i) to (iv), (i) 0% to 30% by weight of (R １ O) ３ P=O, (ii) 5% to 90% by weight of (R １ O) ２ (R ２ O) P=O, (iii) 5% to 90% by weight of (R １ O) (R ２ O) ２ P=O, and (iv) 0% to 30% by weight of (R ２ O) ３ P=O, and R １ and R ２ A mixture according to any one of claims 1 to 4, wherein has the above definition.

6. 6. The mixture according to any one of claims 1 to 5, wherein the phosphorus content, based on the total mass of phosphate esters present, is less than 8.0 wt.%, preferably less than 7.5 wt.%, more preferably less than 7.2 wt.%.

7. 7. The mixture according to claim 1, further comprising one or more flame retardants different from said composition, and optionally one or more auxiliaries.

8. Formula R １ -OH, R ２ —OH, and optionally R ３ -OH phenol and POCl ３ and forming a compound of formula (I).

9. Use of a mixture according to any one of claims 1 to 7 as a flame retardant, preferably as a flame retardant for synthetic polymers, materials of plant origin or materials of animal origin, particularly preferably as a flame retardant for polyvinyl chloride (PVC).

10. A molding compound comprising the mixture according to any one of claims 1 to 7 and polyvinyl chloride (PVC).

11. 11. Moulding compound according to claim 10, comprising 5 to 150 parts by weight, preferably 30 to 70 parts by weight, of the phosphoric acid ester of formula (I), based on 100 parts by weight of PVC.

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

13. Use of a mixture according to any one of claims 1 to 7 as a working fluid.

14. Use of a mixture according to any one of claims 1 to 7 as a lubricant additive.

15. 8. Use of a mixture according to any one of claims 1 to 7 as an additive for paints, adhesives, sealants or coatings.

16. Use of the mixture according to any one of claims 1 to 7 as a heat transfer medium.

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