Chemically resistant polyoxymethylene polymer compositions

Abstract

To provide: polyoxymethylene polymer compositions that are resistant to fuels, particularly diesel fuels, and to highly acidic solutions; and molded articles made from the compositions.SOLUTION: The polymer compositions contain a polyoxymethylene polymer in combination with an acid neutralizing agent and a plasticizer. A polymer composition containing an acid neutralizing agent and a plasticizer at a specific weight ratio generally contains a polyoxymethylene polymer in an amount from about 90 wt.% to about 95 wt.%. In addition, the polymer composition contains an acid neutralizing agent and a plasticizer at a weight ratio that has been found to significantly improve the acid resistance of the composition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001]

[0001] This application is based on and claims priority to U.S. Provisional Patent Application No. 62 / 502,091, filed May 5, 2017, and U.S. Provisional Patent Application No. 62 / 599,373, filed December 15, 2017, both of which are incorporated herein by reference. [Background technology]

[0002]

[0002] Polyacetal polymers, commonly referred to as polyoxymethylene, have become established as highly useful industrial materials in a variety of applications. Polyoxymethylene polymers are widely used, for example, in making molded parts, such as those for use in the automotive and electrical industries. Polyoxymethylene polymers possess, for example, excellent mechanical properties, fatigue resistance, abrasion resistance, chemical resistance, and moldability.

[0003]

[0003] Due to their excellent mechanical properties, heat resistance, and chemical resistance, polyoxymethylene polymers have been used in the past to manufacture parts for various vehicles, such as cars and trucks. For example, because polyoxymethylene polymers do not significantly degrade when in contact with fuel, molded parts made from polyoxymethylene polymers have been used to manufacture fuel lines and other vehicle parts where the parts repeatedly come into contact with vehicle fuel. In addition to being fuel-resistant, polyoxymethylene polymer compositions also have good impact resistance, which makes molded parts made from the polymers resistant to damage or crack formation during normal wear and tear.

[0004] However, certain problems are encountered when polyoxymethylene compositions are designed to come into contact with diesel fuel. For example, diesel fuel may contain sulfur or sulfur-containing compounds. When diesel fuel is heated for extended periods of time, the sulfur-containing compounds may oxidize to form acidic sulfur compounds, which may degrade many different synthetic polymers, including some that may affect polyoxymethylene polymers. Therefore, in the past, polyoxymethylene polymers have been mixed with a variety of different additives, such as hindered amine light stabilizers or zinc oxide, to make the polymer more resistant to contact with corrosive agents that may form in diesel fuel.

[0005] In recent years, an increasing number of cars and trucks have been manufactured with decorative rims for the vehicle's tires. Often, the decorative rims are made of polished metal, chrome, or the like. To clean these materials, consumer and commercial car and truck washes typically use highly acidic wheel cleaners. For example, wheel cleaners may have a pH below 3, or even below 2. Recently, it has been discovered that wheel cleaners, when applied to vehicle rims, are inadvertently sprayed onto fuel system components.

[0006] For example, when wheel cleaner is sprayed onto the rim or tire, the highly acidic cleaner can penetrate through the wheel and remain on the fuel components. Highly acidic solutions, such as wheel cleaners, can rapidly age components made from polyoxymethylene polymers, causing damage over time. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, there is a need for a polyoxymethylene polymer composition that is resistant not only to fuels such as diesel fuel, but also to highly acidic solutions such as wheel cleaners. The need exists. [Means for solving the problem]

[0008]

[0008] Generally, the present invention relates to polymer compositions primarily comprising polyoxymethylene polymers, and molded articles made from such compositions. The polymer compositions of the present invention are formulated to be particularly fuel- and acid-resistant. More specifically, the polymer compositions of the present invention and articles molded from such compositions are well suited for contact with various fuels, such as diesel fuel, and highly acidic liquids, such as various detergents. Even after repeated prolonged contact with fuels and acidic solutions, articles molded in accordance with the present invention do not deteriorate, crack, or otherwise fail.

[0009] For example, in one embodiment, the polymer composition of the present invention comprises a polyoxymethylene polymer in combination with an acid neutralizer and a plasticizer. More specifically, the composition not only comprises greater than at least 60% by weight of a polyoxymethylene polymer, but also includes a specific weight ratio of an acid neutralizer and a plasticizer that has been found to produce a polymer composition that is not only resistant to diesel fuel, but also resistant to many highly acidic fluids, such as wheel and rim cleaners.

[0010] The polyoxymethylene polymer can include, for example, a polyoxymethylene copolymer and can be present in the polymer composition in an amount greater than about 70 wt %, e.g., greater than about 80 wt %, e.g., greater than about 90 wt %. In one embodiment, the polyoxymethylene polymer is present in the polymer composition in an amount less than about 96 wt %, e.g., less than about 95 wt %. The polyoxymethylene polymer can have a melt flow index greater than about 5 g / 10 min, e.g., greater than about 9 g / 10 min, e.g., greater than about 10 g / 10 min, e.g., greater than about 12 g / 10 min, as measured according to ISO Test 1133 at 190°C and a 2.16 kg load. The melt flow index is generally less than about 40 g / 10 min, e.g., less than about 35 g / 10 min, e.g., less than about 30 g / 10 min. In one embodiment, the melt flow index is from about 9 g / 10 min to about 27 g / 10 min.

[0011] As described above, the polyoxymethylene polymer is mixed with an acid neutralizer and a plasticizer. The acid neutralizer can include an oxide, sulfide, or carbonate. The oxide can include, for example, a metal oxide, such as zinc oxide or magnesium oxide. Similarly, the sulfide can include a metal sulfide, such as zinc sulfide or magnesium sulfide. The carbonate can include calcium carbonate. The acid neutralizer can be present in the composition in an amount less than about 2% by weight, for example, less than about 1.5% by weight, for example, less than about 1.2% by weight.

[0012] While acid neutralizers can protect the polymer composition when exposed to diesel fuel and acidic components that may be generated from diesel fuel, acid neutralizers can also make the composition more brittle, especially after exposure to highly acidic solutions. In this regard, acid neutralizers are combined with plasticizers. The plasticizers can include, for example, polyalkylene glycols. The polyalkylene glycols can have an average molecular weight, for example, greater than about 12,000, e.g., from about 25,000 to about 55,000. The plasticizer and acid neutralizer are present in the polymer composition in a weight ratio of about 3:1 to about 20:1, e.g., from about 3.5:1 to about 6:1, e.g., from about 3.5:1 to about 5.5:1. In one embodiment, the plasticizer includes polyethylene glycol.

[0013] In another embodiment, the plasticizer includes an aromatic ester, such as an aromatic polyester, an aliphatic diester, an epoxide, a sulfonamide, a polyether, a polybutene, a polyamine, a terpolymer ... The sugars may include glycerides, acetylated monoglycerides, alkyl citrates, or organic phosphates.

[0014] The plasticizer may be present in the composition in an amount greater than about 3% by weight, such as greater than about 3.5% by weight, for example greater than about 3.8% by weight. The plasticizer is generally present in an amount less than about 8% by weight, for example less than about 6% by weight.

[0015]

[0015] Various other components may be present in the polymer composition to provide various benefits and advantages. Generally, each of the other components and ingredients may be included in the composition in an amount of from about 0.1% to about 10% by weight, for example, from about 0.1% to about 1% by weight.

[0016] For example, in one embodiment, the polymer composition includes a copolyamide, which may be present alone or in combination with ethylene bis(stearamide).

[0017] In one embodiment, an acid scavenger may be present in the composition. The acid scavenger may include tricalcium citrate or calcium carbonate.

[0018] Another component that may be present in the composition is a nucleating agent, which may include, for example, a polyoxymethylene terpolymer.

[0019] As discussed above, the polymer composition is well suited for producing molded articles that come into contact with fuels, such as diesel fuel. The polymer composition is also resistant to highly acidic solutions. For example, in one embodiment, the polymer composition can be used to produce exterior vehicle parts. The molded article can include, for example, a portion of a fuel system for a car or truck. For example, in one embodiment, the molded article can include a component that comes into contact with fuel. The component that comes into contact with fuel can include a fuel line or a fuel flange.

[0019]

[0020] Other features and aspects of the present invention are discussed in more detail below.

[0021] A full and enabling disclosure of the present invention is set forth more particularly in the remainder of the specification, including reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a side view of one embodiment of a fuel line constructed in accordance with the present invention. [Figure 2] FIG. 2 is a perspective view of one embodiment of a fuel flange constructed in accordance with the present invention. [Figure 3] FIG. 3 is a graphical representation of the results obtained in the examples below. DETAILED DESCRIPTION OF THE INVENTION

[0021]

[0022] Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention.

[0023] Reference will now be made in detail to several embodiments of the present invention, one or more examples of which are set forth below. Each example is provided by way of explanation of the invention, not by way of limitation. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield yet a further embodiment. Accordingly, the present invention is intended to cover such modifications and variations.

[0022]

[0024] Generally, the present invention relates to a polyoxymethylene polymer composition and a method for manufacturing the same. The present invention relates to a polymeric article manufactured from a polyoxymethylene polymer. The polymeric composition comprises a polyoxymethylene polymer and has improved fuel resistance, particularly diesel fuel resistance. Furthermore, the polymeric composition of the present invention is also specially formulated to be resistant to highly acidic solutions. In particular, the polymeric composition of the present invention is resistant to highly acidic detergents that may come into contact with the fuel system of a passenger car or truck. Highly acidic solutions may include, for example, wheel cleaners, rim cleaners, chrome cleaners, and the like. Traditionally, polyoxymethylene polymer compositions have been formulated to be resistant to diesel fuel. However, such formulations may be susceptible to damage or degradation when contacted with wheel or rim cleaner solutions that inadvertently come into contact with components or articles comprising the fuel system. To produce a polymeric composition that is not only fuel-resistant but also resistant to highly acidic fluids, the present composition comprises a polyoxymethylene polymer in combination with a specific weight ratio of an acid neutralizer and a plasticizer that has been found to unexpectedly and dramatically improve acid resistance. The acid neutralizing agent may, in one embodiment, include a metal oxide, while the plasticizer may include a polyalkylene glycol having an average molecular weight greater than about 8,000.

[0023]

[0025] Generally, any suitable polyoxymethylene polymer can be incorporated into the polymer composition.

[0026] Polyoxymethylene polymers can be prepared by polymerizing polyoxymethylene-forming monomers, such as trioxane or a mixture of trioxane and a cyclic acetal, such as dioxolane, in the presence of a molecular weight regulator, such as a glycol. The polyoxymethylene polymer used in the polymer composition can include homopolymers or copolymers. In one embodiment, the polyoxymethylene is a homopolymer or copolymer containing at least 50 mol%, such as at least 75 mol%, for example at least 90 mol%, or even at least 97 mol% -CHO- repeating units.

[0024]

[0027] In one embodiment, a polyoxymethylene copolymer is used. The copolymer may contain about 0.1 mol % to about 20 mol %, particularly about 0.5 mol % to about 10 mol %, of repeating units containing a saturated or ethylenically unsaturated alkylene group having at least two carbon atoms or a cycloalkylene group having a sulfur atom or an oxygen atom in the chain, and which may contain one or more substituents selected from the group consisting of alkylcycloalkyl, aryl, aralkyl, heteroaryl, halogen, or alkoxy. In one embodiment, a cyclic ether or acetal is used, which can be introduced into the copolymer by a ring-opening reaction.

[0025]

[0028] Preferred cyclic ethers or acetals have the formula:

[0026] [ka]

[0027] (wherein x is 0 or 1, and R 2 is a C2-C4-alkylene group, where appropriate bearing one or more substituents which are C1-C4-alkylene groups or C1-C4-alkoxy groups and / or halogen atoms, preferably chlorine atoms) By way of example only, mention may be made of cyclic ethers such as ethylene oxide, propylene 1,2-oxide, butylene 1,2-oxide, butylene 1,3-oxide, 1,3-dioxane, 1,3-dioxolane, and 1,3-dioxepane, and comonomers such as linear oligo- or polyformals, such as polydioxolane or polydioxepane. 99.5 to 95 mol % trioxane and 0.5 to 5 mol %, for example 0.5 to 4 It is particularly advantageous to use copolymers composed of 100% by mole of one of the above comonomers.

[0028]

[0029] The polymerization can be carried out as a precipitation polymerization or in the melt. By suitable selection of the polymerization parameters, such as the duration of the polymerization or the amount of molecular weight regulator, the molecular weight of the resulting polymer, and therefore the MVR value, can be controlled.

[0029]

[0030] In one embodiment, the polyoxymethylene polymer used in the polymer composition may contain a relatively large amount of reactive or functional groups at the terminal positions. The reactive groups may include, for example, —OH or —NH groups.

[0030]

[0031] In one embodiment, the polyoxymethylene polymer may optionally have terminal hydroxyl groups, such as hydroxyethylene groups and / or pendant hydroxyl groups, at at least about 50% of all terminal sites on the polymer. For example, the polyoxymethylene polymer may have at least about 70%, such as at least about 80%, such as at least about 85% of its terminal groups, based on the total number of terminal groups present, being hydroxyl groups. It should be understood that the total number of terminal groups present includes all pendant terminal groups.

[0031]

[0032] In one embodiment, the polyoxymethylene polymer optionally has a terminal hydroxyl group content of at least 15 mmol / kg, e.g., at least 18 mmol / kg, e.g., at least 20 mmol / kg. In one embodiment, the terminal hydroxyl group content is in the range of 18 to 50 mmol / kg. In another embodiment, the polyoxymethylene polymer may contain terminal hydroxyl groups in an amount of less than 100 mmol / kg, e.g., less than 50 mmol / kg, e.g., less than 20 mmol / kg, e.g., less than 18 mmol / kg, e.g., less than 15 mmol / kg. For example, the polyoxymethylene polymer may contain terminal hydroxyl groups in an amount of about 5 mmol / kg to about 20 mmol / kg, e.g., about 5 mmol / kg to about 15 mmol / kg. For example, polyoxymethylene polymers having lower terminal hydroxyl group contents but higher melt volume-flow rates can be used.

[0032]

[0033] In addition to or instead of terminal hydroxyl groups, the polyoxymethylene polymer may also have other terminal groups customary for these polymers. Examples of these are alkoxy, formate, acetate, or aldehyde groups. According to one embodiment, the polyoxymethylene is a homo- or copolymer containing at least 50 mol%, for example, at least 75 mol%, for example, at least 90 mol%, or even at least 95 mol% -CHO- repeating units.

[0033]

[0034] In one embodiment, polyoxymethylene polymers can be produced using a cationic polymerization process followed by solution hydrolysis to remove unstable end groups. During cationic polymerization, glycols such as ethylene glycol or methylal can be used as chain terminators. Catalysts can include heteropolyacids, triflic acids, or boron compounds.

[0034]

[0035] The polyoxymethylene polymer may have any suitable molecular weight. The molecular weight of the polymer may be, for example, from about 4,000 g / mol to about 20,000 g / mol. However, in other embodiments, the molecular weight may be significantly greater than 20,000 g / mol, for example, from about 20,000 g / mol to about 100,000 g / mol.

[0035]

[0036] The polyoxymethylene polymer present in the composition generally has a viscosity of about 1 to about 50 g / 10 min, e.g., about 9 g / 10 min, as measured at 190° C. and 2.16 kg according to ISO test 1133. The polyoxymethylene polymer may have a melt flow index (MFI) ranging from about 10 g / 10 min to about 27 g / 10 min, although polyoxymethylenes having higher or lower melt flow indices are also encompassed by the present invention. In one embodiment, the polyoxymethylene polymer generally has a melt flow index greater than about 10 g / 10 min. For example, the polyoxymethylene polymer may have a melt flow index greater than about 11 g / 10 min, or greater than about 12 g / 10 min. The melt flow index of the polyoxymethylene polymer may be less than about 35 g / 10 min, e.g., less than about 30 g / 10 min, e.g., less than about 25 g / 10 min, e.g., less than about 20 g / 10 min, e.g., less than about 14 g / 10 min.

[0036]

[0037] A suitable commercially available polyoxymethylene polymer is available under the trade name Hostaform® (HF) by Celanese / Ticona.

[0038] The polyoxymethylene polymer can be present in the polyoxymethylene polymer composition in an amount of at least 60% by weight, for example at least 70% by weight, for example at least 75% by weight, for example at least 80% by weight, for example at least 85% by weight, for example at least 90% by weight, for example at least 93% by weight. Generally, the polyoxymethylene polymer is present in an amount of less than about 100% by weight, for example less than about 97% by weight, for example less than about 95% by weight, where the weight is based on the total weight of the polyoxymethylene polymer composition.

[0037]

[0039] According to the present invention, a polyoxymethylene polymer is combined with an acid neutralizer and a plasticizer in a ratio that has been found to unexpectedly and dramatically improve the ability of the polymer composition and molded articles made therefrom to withstand highly acidic solutions. The acid neutralizer generally comprises a metal compound and / or oxide, sulfide, or carbonate. Metal oxides that can be used as acid neutralizers include, for example, magnesium oxide and / or zinc oxide. Sulfides that can be used include zinc sulfide, magnesium sulfide, silver sulfide, or molybdenum disulfide. In some instances, the neutralizer comprises calcium carbonate.

[0038]

[0040] For example, in one embodiment, the acid neutralizing agent comprises zinc oxide. The zinc oxide may be present in the polymer composition in the form of particles, such as precipitated particles.

[0041] In one embodiment, the zinc oxide particles have a relatively small particle size range combined with a high surface area. For example, precipitated zinc oxide particles can have a significantly higher surface area than zinc oxide produced by other methods. The acid neutralizer of the present invention can have a surface area of, for example, about 25 m 2 / g, e.g., about 30m 2 / g, e.g., about 35m 2 / g, e.g., about 40m 2 / g, e.g., about 45m 2 / g, e.g., about 50m 2 / g, e.g., about 55m 2 / g. The BET surface area is generally about 100 m 2 / g. By using zinc oxide or other acid neutralizers with relatively high surface areas, the material can be present in minimal amounts. Minimizing the amount of zinc oxide relative to the plasticizer can improve the polymer composition's resistance to wheel cleaner solutions.

[0039]

[0042] Generally, the acid neutralizer is present in the polymer composition in an amount of less than about 10 wt%, for example, less than about 5 wt%, for example, less than about 4 wt%, for example, less than about 3 wt%, for example, less than about 2 wt%. Minimizing the amount of acid neutralizer present in the composition may be desirable in certain applications. In this regard, in one embodiment, the acid neutralizer or zinc oxide may be present in the composition in an amount of less than about 1.5 wt%, for example, less than about 1.2 wt%, or even less than about 1.1 wt%. The acid neutralizer is generally present in an amount greater than about 0.1 wt%, for example, greater than about 0.5 wt%, for example, greater than about 0.7 wt%.

[0040]

[0043] In addition to the polyoxymethylene polymer and the acid neutralizing agent, the polymer composition further comprises a plasticizer, which may be a polyalkylene glycol, an ester, a polyester, an epoxy, or the like. The polymer may include a carboxylic acid, a carboxylic acid, a carboxylic acid copolymer ...

[0041]

[0044] For example, in one embodiment, the plasticizer comprises a polyethylene glycol having a relatively high molecular weight. For example, the average molecular weight of the plasticizer can generally be greater than about 8,000, such as greater than about 15,000, such as greater than about 20,000, such as greater than about 25,000, such as greater than about 30,000, or such as greater than about 35,000. The average molecular weight of the plasticizer is generally less than about 55,000, such as less than about 50,000, such as less than about 45,000, or such as less than about 40,000.

[0042]

[0045] In another embodiment, the plasticizer may have an ester functionality and may include phthalate, adipate, sebacate, maleate, trimellitate, benzoate, or mixtures thereof. Examples of suitable phthalates are diisobutyl phthalate (DIBP), dibutyl phthalate (DBP), diisoheptyl phthalate (DIHP), L79 phthalate, L711 phthalate, dioctyl phthalate, diisooctyl phthalate, dinonyl phthalate, diisononyl phthalate, diisodecyl phthalate, L911 phthalate, diundecyl phthalate, diisoundecyl phthalate, undecyldodecyl phthalate, diisotridecyl phthalate (DTDP), and butyl benzyl phthalate (BBP).

[0043]

[0046] Examples of adipates are dioctyl adipate, diisononyl adipate, and diisodecyl adipate. An example of a trimellitate is trioctyl trimellitate. Phosphate esters can also be used. Suitable examples are tri-2-ethylhexyl phosphate, 2-ethylhexyl diphenyl phosphate, and tricresyl phosphate.

[0044]

[0047] Sebacates and azelates include di-2-ethylhexyl sebacate (DOS) and di-2-ethylhexyl azelate (DOZ).

[0048] Polyester plasticizers are usually based on the condensation products of propanediol or butanediol with adipic acid or phthalic anhydride. The growing polymer chains of these polyesters can then be end-capped with alcohols or monobasic acids, although strict control of the reaction stoichiometry can produce unend-capped polyesters.

[0045]

[0049] Further plasticizers are benzoates commercially available as JAYFLEX® MB10, BENZOFLEX® 2088, BENZOFLEX® LA-705, and BENXOFLEX® 9-88. Epoxide-based plasticizers include epoxidized vegetable oils.

[0046]

[0050] In one embodiment, the plasticizer is an aromatic benzenesulfonamide.

[0047] [ka]

[0048] (wherein R1 represents a hydrogen atom, a C1-C4 alkyl group, or a C1-C4 alkoxy group.) , X is linear or branched C2 to C 10 represents an alkylene group, an alkyl group, a methylene group, an alicyclic group, or an aromatic group; Y represents a group H, OH, or

[0049] [ka]

[0050] wherein R2 represents a C1-C4 alkyl group or an aromatic group, which is optionally itself substituted by OH or a C1-C4 alkyl group. represents one of Preferred are benzenesulfonamides represented by:

[0051] Preferred aromatic benzenesulfonamides of formula (I) are those in which R1 represents a hydrogen atom or a methyl or methoxy group and X is a linear or branched C2-C 10 represents an alkylene group or a phenyl group, Y represents H, OH, or an —O—CO—R group, R representing a methyl or phenyl group, R being optionally itself substituted by an OH or methyl group.

[0052] Among the aromatic sulfonamides of formula (I), mention may be made of the following products (shown below together with the abbreviations assigned to them) which are liquid (L) or solid (S) at room temperature:

[0053] N-(2-hydroxyethyl)benzenesulfonamide (L); N-(3-hydroxypropyl)benzenesulfonamide (L); N-(2-hydroxyethyl)-p-toluenesulfonamide (S); N-(4-hydroxyphenyl)benzenesulfonamide (S); N-[(2-hydroxy-1-hydroxymethyl-1-methyl)ethyl]benzenesulfonamide (L); N-[5-hydroxy-1,5-dimethylhexyl]benzenesulfonamide (S); N-(2-(acetoxyethyl)benzenesulfonamide (S); N-(5-hydroxypentyl)benzenesulfonamide (L); N-[2-(4-hydroxybenzoyloxy)ethyl]benzenesulfonamide (S); N-[2-(4-methylbenzoyloxy)ethyl]benzenesulfonamide (S); N-(2-hydroxyethyl)-p-methoxybenzenesulfonamide (S); and N-(2-hydroxypropyl)benzenesulfonamide (L).

[0054] One particular plasticizer is a sulfonamide, such as N-(n-butyl)benzenesulfonamide. It has been unexpectedly discovered that controlling the ratio between the plasticizer and the acid neutralizer has a dramatic and unexpected effect on the ability of the polymer composition to withstand highly acidic solutions, such as solutions having a pH of less than about 3, e.g., less than about 2. For example, the plasticizer can be present relative to the acid neutralizer such that the weight ratio of plasticizer to acid neutralizer is from about 3:1 to about 20:1. The weight ratio between the plasticizer and the acid neutralizer can be, for example, from about 3:1 to about 6:1, e.g., from about 3.5:1 to about 5.5:1, e.g., from about 3.8:1 to about 5.2:1.

[0055] As explained above, the actual amount of plasticizer present in the polymer composition may vary depending on the amount of plasticizer present. The amount of plasticizer present in the composition can be determined by the amount of acid neutralizer present and various other factors. Generally, the plasticizer is present in the composition in an amount greater than about 2 wt%, for example, greater than about 3 wt%, for example, greater than about 3.5 wt%, for example, greater than about 3.8 wt%. The plasticizer is generally present in an amount less than about 12 wt%, for example, less than about 8 wt%, for example, less than about 6 wt%, for example, less than about 5 wt%.

[0056] In addition to the polyoxymethylene polymer, acid neutralizer, and plasticizer, various other ingredients and components can be included in the composition to improve one or more properties. For example, in one embodiment, the composition can include a conductive filler so that any article molded from the composition exhibits electrostatic dissipation (ESD) capabilities. The conductive filler can include conductive particles, powders, fibers, or combinations thereof. For example, the conductive filler can include metal powder, metal flakes, metal fibers (i.e., stainless steel fibers), carbon powder, carbon fibers, carbon black, carbon nanotubes, or combinations thereof.

[0057]

[0057] Furthermore, the conductive filler may be present in the polymer composition of the present invention in an amount ranging from about 1% by weight to about 30% by weight, for example, in an amount ranging from about 1.5% by weight to about 25% by weight, for example, in an amount ranging from about 2% by weight to about 20% by weight, based on the total weight of the polymer composition.

[0058] In one embodiment, a formaldehyde scavenger, such as a nitrogen-containing compound, can be present. These are primarily heterocyclic compounds having at least one nitrogen atom as a heteroatom adjacent to either an amino-substituted carbon atom or a carbonyl group, such as pyridine, pyrimidine, pyrazine, pyrrolidone, aminopyridine, and compounds derived therefrom. Other particularly advantageous compounds are triamino-1,3,5-triazine (melamine) and its derivatives, such as melamine-formaldehyde condensates and methylolmelamine. In one embodiment, the formaldehyde scavenger present in the composition comprises melamine. Oligomeric polyamides are also, in principle, suitable for use as formaldehyde scavengers.

[0059] In one embodiment, the formaldehyde scavenger comprises a guanamine compound. Examples of the guanamine compound include aliphatic guanamine compounds, alicyclic guanamine compounds, aromatic guanamine compounds, and heteroatom-containing guanamine compounds. In one embodiment, the guanamine compound comprises benzoguanamine.

[0060] The polymer composition can contain a single formaldehyde scavenger or a blend of formaldehyde scavengers. Generally, the formaldehyde scavenger is present in the composition in an amount of at least about 0.01 wt%, for example, at least about 0.03 wt%, for example, at least about 0.05 wt%. The formaldehyde scavenger is generally present in an amount of less than about 2 wt%, for example, less than about 1.5 wt%, for example, less than about 1 wt%, for example, less than about 0.5 wt%, for example, less than about 0.1 wt%.

[0061] In one embodiment, one or more formaldehyde scavengers can be combined with the copolyamide, which can also enhance the ability of the composition to reduce formaldehyde emissions.

[0062] The copolyamide may generally have a softening point greater than about 120° C., such as greater than about 130° C., for example greater than about 140° C., for example greater than about 150° C., for example greater than about 160° C., for example greater than about 170° C. The softening point of the copolyamide may be less than about 210° C., for example less than about 200° C., for example less than about 190° C., for example less than about 185° C. The copolyamide may have a melt viscosity at 230°C greater than about 7 Pa·s, e.g., greater than about 8 Pa·s, e.g., greater than about 9 Pa·s. The melt viscosity is generally less than about 15 Pa·s, e.g., less than about 14 Pa·s, e.g., less than about 13 Pa·s. In one embodiment, the copolyamide is ethanol soluble. In one embodiment, the copolyamide can include a polycondensation product of a polymeric fatty acid and an aliphatic diamine. The copolyamide can generally be present in the composition in an amount greater than about 0.01 wt%, e.g., greater than about 0.03 wt%, e.g., greater than about 0.05 wt%. The copolyamide is generally present in an amount less than about 2 wt%, e.g., less than about 1.5 wt%, e.g., less than about 1 wt%, e.g., less than about 0.5 wt%, e.g., less than about 0.1 wt%.

[0063] In one embodiment, an acid scavenger can be present. The acid scavenger can include, for example, an alkaline earth metal salt. For example, the acid scavenger can include a calcium salt, such as calcium citrate or calcium carbonate. In one embodiment, the acid scavenger can include tricalcium citrate. The acid scavenger can be present in an amount of at least about 0.01% by weight, such as at least about 0.05% by weight, for example, at least about 0.09% by weight. In one embodiment, a greater amount of acid scavenger is used, such as when the acid scavenger is a carbonate salt. For example, the acid scavenger can be present in an amount greater than about 2% by weight, such as greater than about 5% by weight, for example, greater than about 7% by weight. The acid scavenger is generally present in an amount less than about 10 wt%, such as less than about 7 wt%, for example less than about 5 wt%, for example less than about 1 wt%, for example less than about 0.75 wt%, for example less than about 0.5 wt%, where weight is based on the total weight of the respective polymer composition.

[0064] In one embodiment, a nucleating agent can be present. The nucleating agent can increase crystallinity and can include an oxymethylene terpolymer. In one particular embodiment, for example, the nucleating agent can include a terpolymer of butanediol diglycidyl ether, ethylene oxide, and trioxane. In one embodiment, the terpolymer nucleating agent can have a relatively small particle size, for example, less than about 1 micron, for example, less than about 0.8 microns, for example, less than about 0.6 microns, for example, less than about 0.4 microns, and generally having a d50 particle size greater than 0.01 microns. Other nucleating agents that can be used include polyamide, boron nitride, or talc. The polyamide nucleating agent can be PA6 or PA12. The nucleating agent may be present in the composition in an amount of at least about 0.01 wt.%, such as at least about 0.05 wt.%, for example at least about 0.1 wt.%, and less than about 2 wt.%, for example less than about 1.5 wt.%, for example less than about 1 wt.%, where weight is based on the total weight of the respective polymer composition.

[0065] In one embodiment, an antioxidant such as a sterically hindered phenol can be present. Commercially available examples are pentaerythrityl tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate], 3,3'-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionohydrazide], and hexamethylene glycol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. The antioxidant may be present in the polymer composition in an amount of at least about 0.01 wt.%, such as at least about 0.05 wt.%, for example at least about 0.1 wt.%, for example at least about 0.2 wt.%, and less than about 1 wt.%, for example less than about 0.75 wt.%, for example less than about 0.5 wt.%, where weight is based on the total weight of the respective polymer composition.

[0066] In one embodiment, a lubricant can be present. The lubricant can include a polymer wax composition. In one embodiment, the lubricant can include ethylene bis(stearamide) In another embodiment, the lubricant can include a polyalkylene glycol having a relatively low molecular weight compared to the plasticizer. For example, the lubricant can include polyethylene glycol having an average molecular weight of about 1,000 to about 5,000, e.g., about 3,000 to about 4,000. The lubricant can generally be present in the polymer composition in an amount of at least about 0.01 wt %, e.g., at least about 0.05 wt %, e.g., at least about 0.1 wt %, and less than about 1 wt %, e.g., less than about 0.75 wt %, e.g., less than about 0.5 wt %, where weight is based on the total weight of the respective polymer composition.

[0067] In one embodiment, a colorant can be present. Colorants that can be used include any desired inorganic pigment, such as titanium dioxide, ultramarine blue, or cobalt blue, as well as other organic pigments and dyes, such as phthalocyanines and anthraquinones. Other colorants include carbon black or various other polymer-soluble dyes. In one embodiment, a combination of colorants can be included in the polymer composition. For example, carbon black can be included in the polymer composition. In another embodiment, the colorant present in the polymer composition can include titanium dioxide in combination with at least one colored pigment, such as a yellow pigment and a green pigment, and optionally further in combination with carbon black. The colorant can be present in the composition in an amount of at least about 0.01 wt %, such as at least about 0.05 wt %, such as at least about 0.1 wt %, such as at least about 0.5 wt %, and less than about 5 wt %, such as less than about 2.5 wt %, such as less than about 1 wt %, where weight is based on the total weight of the respective polymer composition.

[0068] When a colorant is present, one or more light stabilizers can also be included in the composition. In one embodiment, a light stabilizer such as a sterically hindered amine can be present in addition to an ultraviolet light stabilizer. Hindered amine light stabilizers that can be used include N-methylated oligomeric hindered amine compounds. For example, the hindered amine light stabilizer can include a polymeric hindered amine stabilizer. When present, the light stabilizer can be present in the polymer composition in an amount of at least about 0.01 wt %, such as at least about 0.05 wt %, for example at least about 0.075 wt %, and less than about 1 wt %, for example less than about 0.75 wt %, for example less than about 0.5 wt %, where the weight is based on the total weight of the respective polymer composition.

[0069] In one embodiment, an ultraviolet light stabilizer can be present. The ultraviolet light stabilizer can include benzophenones, benzotriazoles, or benzoates. When present, the UV light absorber can be present in the polymer composition in an amount of at least about 0.01 wt %, such as at least about 0.05 wt %, for example at least about 0.075 wt %, and less than about 1 wt %, for example less than about 0.75 wt %, for example less than about 0.5 wt %, where weight is based on the total weight of the respective polymer composition.

[0070]

[0070] However, in one embodiment, the polymer composition does not include a light stabilizer. For example, the composition may be free of ultraviolet light stabilizers or hindered amine light stabilizers.

[0071] The polymer composition may also optionally include one or more reinforcing agents. For example, the polymer composition may include reinforcing fibers such as glass fibers, carbon fibers, etc. The reinforcing fibers may generally be present in an amount of from about 2% to about 25% by weight.

[0071]

[0072] In another embodiment, the polymer composition can include reinforcing particles having a high aspect ratio. The particles can include, for example, glass flake, mica, loam, graphite, molybdenum disulfide, and mixtures thereof. The particles have an aspect ratio of greater than about 1.5. The reinforcing filler may have an aspect ratio of greater than about 2, such as greater than about 2.5, for example greater than about 3, such as greater than about 3.5, for example greater than about 4, such as greater than about 4.5, for example greater than about 5, and generally less than about 20, such as less than about 15, for example less than about 12. The reinforcing filler may generally be present in the composition in an amount of from about 2% to about 25% by weight.

[0072]

[0073] The compositions of the present invention can be compounded and formed into polymeric articles using any technique known in the art. For example, the individual compositions can be vigorously mixed to form a substantially homogeneous blend. The blend can be melt-kneaded at an elevated temperature, such as a temperature above the melting point but below the decomposition temperature of the polymers used in the polymeric composition. Alternatively, the individual compositions can be melted and mixed together in a conventional single- or twin-screw extruder. Preferably, melt-mixing is carried out at a temperature ranging from 100 to 280°C, e.g., 120 to 260°C, e.g., 140 to 240°C, or 180 to 220°C.

[0073]

[0074] After extrusion, the composition can be formed into pellets, which can be formed into polymeric articles by techniques known in the art, such as injection molding, thermoforming, blow molding, rotational molding, and the like.

[0074]

[0075] In one embodiment, the polymer composition can be used to manufacture a polymer article designed for the automotive field. The polymer article can be designed to be, for example, an exterior vehicle part. In one embodiment, the molded article is molded into a fuel-contacting component. The fuel-contacting component can be, for example, one or more components included in the fuel system of a vehicle, such as a car or truck. The fuel-contacting component can be designed to be in repeated contact with, for example, diesel fuel.

[0075]

[0076] For example, referring to Figure 1, there is shown a fuel line 100 formed from the polymer composition of the present invention. The fuel line 100 includes, for example, in this embodiment, a corrugated tube.

[0076]

[0077] In addition to fuel lines, the polymer compositions of the present invention can be used to manufacture fuel tanks, fuel pump components, fuel filter components, fuel rails, injector components, pressure regulators, and return fuel lines.

[0077]

[0078] In one embodiment, the polymer composition is used to manufacture a fuel flange 200, as shown in Figure 2. The fuel flange 200 is designed to be placed on, for example, a fuel tank and connected to one or more fuel lines. For example, as shown in Figure 2, the fuel flange 200 can include at least one fuel inlet or outlet 202 for supplying fuel to and dispensing fuel from the fuel tank. The fuel flange 200 can also include an electrical connector 204 for connecting a controller housed within the vehicle to various sensors that may be present in and around the fuel tank.

[0078]

[0079] The present invention may be better understood with reference to the following examples. [Example]

[0079]

[0080] The following examples are provided to further illustrate the present invention, but not to limit its scope. Other variations of the present invention will be readily apparent to those skilled in the art and are encompassed by the appended claims.

[0080] Example 1:

[0081] In this example, various polymer compositions were blended to evaluate their resistance to highly acidic solutions. The highly acidic solution used was a wheel cleaner solution.

[0081]

[0082] The following polymer compositions were formulated:

[0082] [Table 1]

[0083] The above polymer compositions were molded into test plaques and tested against wheel cleaner solutions. The wheel cleaner solutions used were marketed by Eagle One of Draper, Utah. It was EAGLE ONE Chrome Wheel Cleaner, which is sold. It had a pH of 0.3 and contained the following acidic components:

[0084] [Table 2]

[0085] Testing was performed by spraying the solution onto distorted molded parts. A 2% distortion was achieved by applying a 77.8 mm radius of curvature to a 3 mm thick part. The solution was sprayed four times per day, and the parts were monitored hourly for day 1, twice daily for days 2-7, and once daily thereafter. General procedures and guidelines for visual inspection were as follows:

[0086] Steps: 1. Each sample is covered with a layer of gauze and placed on the bending jig. The gauze It is placed there to ensure uniform coverage. The gauze is left on the surface during aging. 2. Subject the specimen to a 2% strain. (There should not be any significant difference between materials at 2% strain. 3. Spray the stressed specimens with Eagle One Chrome Wheel Cleaner four times daily. Recommended times: 8:00 AM, 11:00 AM, 2:00 PM, and 5:00 PM. 4. Give the sample one even spray unless a second spray is needed for even and consistent coverage. a. Check pH periodically for the first few days to ensure stable exposure. 5. Remove the gauze and record signs of cracking according to the following schedule: a. Day 1 (once per hour until the end of the day); b. Days 2-7 (twice a day at the beginning and end of each work shift); c. Days 8-25 (once a day during working days only); 6. Continue this process for 25 days.

[0087]

[0089] Visual inspection: 1. Day 1 - Samples are taken every hour between 8:00 AM and 5:00 AM. 2. Days 2-5 - Samples should be tested three times per day during normal workdays only. Recommended times: 8:00 AM, 1:00 PM, and 5:00 PM.

[0088] 3. Days 6-25 - Samples will be tested once daily during normal workdays only. 4. Record all observations as follows: O means the sample is OK, Δ means the sample has small surface cracks, X means there is a 12mm long crack, XX means the sample is cracked all over.

[0089] 5. Take a photographic record of any cracks or deterioration of the surface within 25 days.

[0090] The results are shown in Figure 3.

[0091] As shown, Sample 3 significantly outperformed Samples 1 and 2 in the wheel cleaner resistance test. Sample 3 contained a 4:1 weight ratio of plasticizer to acid neutralizer.

[0090]

[0092] Different polymer compositions were also tested for various physical properties, with the following results:

[0091] [Table 3]

[0092] Example 2:

[0093] Polymer compositions were formulated in accordance with the present invention and tested for various physical properties. Polymer composition sample #4 contained the following ingredients:

[0093] [Table 4]

[0094] The above polymer compositions were molded into various test plaques with the following results:

[0095] [Table 5]

[0096] These and other modifications and variations to the present invention are set forth in the appended claims. It will be understood that the present invention may be practiced by those skilled in the art without departing from the spirit and scope of the invention as set forth in the specification. Furthermore, the various aspects of the invention may be interchangeable both in whole or in part. It should be further understood by those skilled in the art that the foregoing description is for illustrative purposes only and It is recognized that no limitation of the invention is intended, as further set forth in the appended claims. It will. The claims as filed are as follows: [Claim 1] 1. A polymer composition comprising: The polyoxymethylene polyethylene glycol is present in the polymer composition in an amount of at least about 60% by weight. Rimmer; an acid neutralizing agent present in the polymer composition in an amount less than about 2.5% by weight; and Plasticizers; the plasticizer and the acid neutralizer are mixed with the polymer in a weight ratio of about 3:1 to about 20:1. The polymer composition is present in a composition. [Claim 2] The plasticizer is present in the polymer in an amount greater than about 3% by weight, for example, greater than about 3.5% by weight. The polymer composition of claim 1, wherein the polymer composition is present in the composition. [Claim 3] 3. The polymer composition of claim 1, wherein the plasticizer comprises a polyalkylene glycol. thing. [Claim 4] The polyalkylene glycol has an average molecular weight of about 8,000 to about 55,000 g / mol. 4. The polymer composition according to claim 1, wherein the polymer composition comprises: [Claim 5] The acid neutralizer comprises an oxide, sulfide, or carbonate, and is about 25 m 2 / g or greater BE 5. The polymer composition according to claim 1, having a surface area of ​​T. [Claim 6] The plasticizer and the acid neutralizer are mixed in a weight ratio of about 3.5:1 to about 4.5:1 with the polymer. The polymer composition according to any one of claims 1 to 5, which is present in the composition. [Claim 7] 7. The polymer composition according to claim 1, wherein the polymer composition further comprises tricalcium citrate. The polymer composition described above. [Claim 8] 8. The method according to claim 1, wherein the polymer composition further comprises ethylene bis(stearamide). The polymer composition according to any one of claims 1 to 4. [Claim 9] The polyoxymethylene polymer is present in an amount greater than about 90% by weight, for example, greater than about 93% by weight. The polymer according to any one of claims 1 to 8, which is present in the polymer composition in an amount greater than or equal to 100% by weight of the polymer. composition. [Claim 10] The polymer composition according to any one of claims 1 to 9, wherein the polymer composition further comprises a copolyamide. Mer composition. [Claim 11] The acid neutralizing agent is added to the polymer in an amount of less than about 1.5 wt. %, for example, less than about 1.2 wt. %. The polymer composition according to any one of claims 1 to 10, which is present in a polymer composition. [Claim 12] The polyoxymethylene polymer is resistant to 190°C and 2.1°C according to ISO test 1133. Tested with a load of 6 kg, the resistance is higher than about 10 g / 10 min, for example, higher than about 12 g / 10 min. 12. The polymer composition according to claim 1, having a low flow index. [Claim 13] 10. The composition according to claim 1, wherein the composition further comprises ethylene bis(stearamide) and a copolyamide. 8. The polymer composition according to any one of 7. [Claim 14] 14. The polymer composition according to claim 1, wherein the composition further comprises a nucleating agent. [Claim 15] The nucleating agent is selected from the group consisting of polyoxymethylene terpolymer, boron nitride, polyamide, and talc. 15. The polymer composition of claim 14, comprising: [Claim 16] the acid neutralizing agent comprises zinc oxide, the zinc oxide being present in an amount less than about 1.5% by weight; The plasticizer is polyethylene glycol having a molecular weight of about 25,000 to about 55,000. wherein the polyethylene glycol is present in the polymer composition in an amount greater than about 3% by weight. The composition contains a nucleating agent, an antioxidant, ethylene bis(stearamide), tricitric acid 10. The polymer of claim 1 or 5, further comprising calcium, a copolyamide, and melamine. composition. [Claim 17] The plasticizer may be an aromatic ester, an aliphatic diester, an epoxide, a sulfonamide, a polyol, or a mixture thereof. 3. The method according to claim 1 or 2, comprising: The polymer composition described above. [Claim 18] 10. The method according to claim 1 or 5, wherein the acid neutralizing agent comprises magnesium oxide or calcium carbonate particles. The polymer composition described above. [Claim 19] The polymer composition further comprises a reinforcing agent, the reinforcing agent being selected from the group consisting of reinforcing fibers, glass flakes, 19. The polymer composition according to claim 1, comprising mica or a mixture thereof. . [Claim 20] A molded article produced from the polymer composition according to any one of claims 1 to 19, The molded article comprises an exterior vehicle part. [Claim 21] 21. The molded article of claim 20, wherein the exterior vehicle part comprises a fuel contact member. [Claim 22] 21. The molded article of claim 20, wherein the molded article comprises a fuel line. [Claim 23] 21. The molded article of claim 20, wherein the molded article comprises a fuel flange.

Claims

1. 1. A polymer composition comprising: a polyoxymethylene polymer present in said polymer composition in an amount of at least about 60% by weight, said polyoxymethylene polymer comprising a polyoxymethylene copolymer containing a comonomer in an amount of 0.5 to 4 mole %; An acid neutralizer, the acid neutralizer consisting solely of magnesium oxide, the acid neutralizer having a concentration of about 55 m ２ / g of an acid neutralizing agent having a BET surface area of ​​greater than 1.0; a plasticizer present in said polymer composition in an amount less than 12% by weight, said plasticizer comprising polyethylene glycol having an average molecular weight of from about 25,000 to about 55,000; an acid scavenger comprising calcium citrate; and Nucleating agent containing polyoxymethylene terpolymer The polymer composition comprising:

2. 1. A polymer composition comprising: The polyoxymethylene polymer present in the polymer composition in an amount of at least about 60% by weight, the polyoxymethylene polymer containing a comonomer in an amount of 0.5 to 4 mole percent. polyoxymethylene polymer containing polymers; An acid neutralizer, the acid neutralizer consisting solely of magnesium oxide, the acid neutralizer having a concentration of about 55 m ２ / g of an acid neutralizing agent having a BET surface area of ​​greater than 1.0; a plasticizer present in said polymer composition in an amount less than 12% by weight, said plasticizer comprising polyethylene glycol having an average molecular weight of from about 25,000 to about 55,000; an acid scavenger comprising calcium citrate; and Lubricants containing ethylene bis(stearamide) The polymer composition comprising:

3. 3. The composition of claim 1 or 2, wherein the polyoxymethylene polymer is a polyoxymethylene copolymer.

4. The polymer composition of claim 3, wherein the comonomer comprises 1,3-dioxolane.

5. 5. The polymer composition of claim 1, wherein the polyoxymethylene polymer has a terminal hydroxyl group content of from about 5 mmol / kg to about 20 mmol / kg.

6. The polymer composition of claim 5 , wherein the polyoxymethylene polymer further comprises a terminal group comprising an alkoxy group.

7. The polymer composition of any one of claims 1 to 6, wherein the polyoxymethylene polymer is present in the polymer composition in an amount greater than about 80% by weight.

8. The polymer composition according to any one of claims 1 to 7, wherein the polyoxymethylene polymer has a melt flow index higher than 5 g / 10 min and lower than 30 g / 10 min.

9. The polymer composition according to any one of claims 1 to 8, wherein the polyoxymethylene polymer has a melt flow index of from 9 g / 10 min to 27 g / 10 min.

10. The polymer composition of any one of claims 1 to 9, wherein the acid neutralizing agent is present in the polymer composition in an amount greater than 0.7 wt% and less than 10 wt%.

11. The polymer composition of any one of claims 1 to 10, wherein said polyethylene glycol has an average molecular weight that is less than 40,000 g / mol.

12. The polymer composition according to any one of claims 1 to 11, further comprising a sterically hindered phenol.

13. The polymer composition of claim 12, wherein the sterically hindered phenol comprises pentaerythrityl tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

14. The polymer composition of any one of claims 1 to 13, further comprising a reinforcing agent comprising reinforcing fibers, glass flakes, mica, or mixtures thereof.

15. 3. The polymer composition of claim 1, wherein the comonomer comprises 1,3-dioxolane, the polyoxymethylene polymer has a terminal hydroxyl group content of from about 5 mmol / kg to about 20 mmol / kg, the polyoxymethylene polymer further comprises end groups comprising alkoxy groups, the acid neutralizing agent is present in the polymer composition in an amount greater than 0.7 wt % and less than 10 wt %, the plasticizer is present in the polymer composition in an amount greater than 2 wt %, the polyoxymethylene polymer has a melt flow index greater than 5 g / 10 min and less than 30 g / 10 min, and the composition further comprises a sterically hindered phenol.

16. 16. The polymer composition of claim 1, further comprising at least one selected from the group consisting of a nucleating agent or a lubricant.

17. A molded article made from the polymer composition of any one of claims 1 to 16, said molded article comprising an exterior vehicle part, said polymer composition comprising said polyoxymethylene terpolymer.

18. 20. The molded article of claim 17, wherein the exterior vehicle part comprises a fuel contact member.

19. 18. The molded article of claim 17, wherein the molded article comprises a fuel line.

20. The molded article of claim 17 , wherein the molded article comprises a fuel flange.

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