Polyformaldehyde polymers containing aldehyde scavengers

Abstract

The present invention provides a method of reducing aldehyde content, increasing oxidation induction time (OIT) and / or improving thermal stability in a polyoxymethylene (POM) polymer comprising contacting the POM polymer with an aldehyde scavenger selected from the group consisting of: (i) a compound XX comprising at least three moieties (AA) # imgabs0 # wherein each moiety (AA) comprises an amine moiety (-NH2) ortho or meta bonded to an amide moiety (-CONH), each R1 independently represents a substituent, m is an integer from 0 to 4; and the three moieties (AA) are bound by their respective amide nitrogen atoms to the respective carbon atoms of the host fragment, wherein the host fragment comprises only carbon and hydrogen atoms and is saturated; and (ii) a cyanoacetamide.

Description

Technical Field

[0001] The present invention relates to polymeric materials, particularly but not limited to polyoxymethylene (POM), to which aldehydes may be undesirably bound, for example due to generation during manufacture of the polymeric material, during downstream melt processing of the polymeric material and / or during use. Background Art

[0002] Polyoxymethylene (POM) is also known as acetal, polyacetal or polyoxymethylene. It is a polymer with a linear ether structure (CH2O-)n along its backbone. This linearity results in a high crystallinity of up to 80% and a high crystallinity of 1.410-1.420 g / cm 3 In some cases, POM can be filled (for example with glass fibers or carbon fibers).

[0003] Polyoxymethylene is increasingly used in a wide range of applications, including electrical and electronics, consumer products, automotive and industrial machinery, medical devices, building and construction.

[0004] POM can be sold as a copolymer or homopolymer. POM homopolymer has the following structure

[0005]

[0006] It is mainly composed of the above-mentioned repeating units.

[0007] POM copolymers include the following repeating units:

[0008]

[0009] It is mainly composed of the above-mentioned repeating units.

[0010] Both POM homopolymers and POM copolymers use methanol as the main base raw material. For POM homopolymers, formaldehyde is synthesized by air oxidation of methanol, followed by the use of ionic initiators to form acetal resins. The resins in POM homopolymers are stabilized by substitution of ester groups for the hydroxyl groups at the ends of the polymer chains. POM copolymers are usually produced using trioxane as a raw material (also starting with methanol). About 2-3% of an epoxy compound is copolymerized with trioxane to give a stable POM copolymer. Chain end-capping agents may also be used. POM copolymer resins have a higher stability, but a reduced crystallinity due to the carbon-carbon bonded groups interspersed in their polymer chains. This polymer structure also has excellent resistance to alkalis, hot water, and other chemicals, as well as a long life at high temperatures and greater freedom in processing conditions. On the other hand, its tensile strength, stiffness, softening point, and melting point are lower than those of acetal homopolymers.

[0011] Polyoxymethylene (POM) is inherently unstable and susceptible to polymer degradation. POM degradation occurs via chain scission or end group decomposition. Common degradation products are formaldehyde, formic acid, cyclic acetals, and oligomers. Melt processing of POM results in polymer degradation, which produces formaldehyde. Formaldehyde emissions lead to workplace safety challenges during polymer processing and limit the use of polymers in applications where air quality is critical, such as automotive applications.

[0012] Formaldehyde produced by polymer degradation can be oxidized to formic acid, which contributes to the hydrolysis of the polymer chains. In addition to formaldehyde emissions, POM degradation can also lead to mold deposits, reduced mechanical properties and discoloration.

[0013] POM resins can also be sensitive to acid hydrolysis by inorganic acids. For example, low levels of chlorine in drinking water can lead to environmental stress cracking. Therefore, POM parts are stabilized to mitigate this degradation.

[0014] It is known that measures can be taken to stabilize POM and reduce aldehyde emissions. For example, steps to achieve stabilization can be applied at the final stage of POM production or during melt processing to form an article or masterbatch. Methods that have been developed to prevent POM degradation include phenolic antioxidants to limit oxidative degradation, lubricants to reduce shear forces, acid scavengers to prevent formic acid hydrolysis, scavengers to react with free formaldehyde, the use of end-capping agents, light stabilizers and / or comonomers to improve stability.

[0015] In addition to the aldehyde generation problem described above, POM is susceptible to thermally induced oxidative decomposition. The relative thermo-oxidative stability of POM polymers can be assessed by measuring the oxidative induction time (OIT). A relatively high OIT is preferred.

[0016] Although various stabilization assemblies are used commercially, it is challenging to reduce aldehyde emission in POM and improve its thermal stability as indicated by the increase in OIT. Summary of the invention

[0017] It is an object of the present invention to solve one or more of the above problems.

[0018] According to a first aspect of the present invention, there is provided a method for reducing the aldehyde (e.g., formaldehyde) content in a polyoxymethylene (POM) polymer and / or increasing the oxidative induction time (OIT) and / or improving thermal stability, the method comprising the step of contacting the POM polymer or a monomer, oligomer or prepolymer involved in preparing the POM polymer with an aldehyde scavenger selected from the following:

[0019] (i) a compound XX comprising at least three moieties (AA) of the formula

[0020]

[0021] wherein each moiety (AA) comprises an amine moiety (-NH2) bonded ortho or meta to an amide moiety (-CONH);

[0022] Each R 1 independently represents a substituent, and m is an integer from 0 to 4; and

[0023] wherein the three moieties (AA) are bonded via their respective amide nitrogen atoms to respective carbon atoms of a main fragment, wherein the main fragment comprises only carbon and hydrogen atoms and is saturated; and

[0024] (ii) cyanoacetamide, for example, having the general formula

[0025]

[0026] Where R 60 and R 61 independently represent a hydrogen atom or an optionally substituted, preferably unsubstituted, alkyl, cycloalkyl or aryl group; and

[0027] Where R 62 and R 63 independently represents a hydrogen atom or an optionally substituted, preferably unsubstituted alkyl, cycloalkyl or aryl group; or R 62 and R 63 Together they define optionally substituted alkenyl.

[0028] The appropriate reduction of aldehydes mentioned in this article refers primarily to formaldehyde, which, as mentioned earlier, is a particular problem in the context of POM.

[0029] The method preferably reduces the aldehyde content in the POM when evaluated according to VDA-275. The method suitably improves the thermal stability of the POM and increases the OIT, which can be described in Evaluation 3.

[0030] The POM suitably comprises a -(CH2O)- repeating unit (referred to as "repeating unit X"). It may also comprise a -(CH2CH2O)- repeating unit (referred to as "repeating unit Y"). Preferably, in the POM, the sum of the mol % of repeating units X and Y is at least 80 mol %, preferably at least 90 mol %, more preferably at least 95 mol %, especially about 100 mol %.

[0031] In the POM, the weight percentage of the POM polymer composed of repeating units X and Y is at least 80 weight %, preferably at least 90 weight %, more preferably at least 95 weight %, and in particular at least 98 weight %.

[0032] The POM is a POM homopolymer, which suitably consists essentially of repeating units X, or may be a POM copolymer, which suitably consists essentially of repeating units X and Y.

[0033] In the compound XX, one R 1 or each R 1 Can be selected from halogen atoms, or optionally substituted hydrocarbyl, alkoxyl, amido, amide groups, phenolic or carboxyl groups. The optionally substituted hydrocarbyl can be substituted by one or more halogen atoms or alkoxyl, amido, amide groups, phenolic or carboxyl groups. The optionally substituted hydrocarbon is preferably unsubstituted.

[0034] One R 1 or multiple R 1 It may be optionally substituted, preferably unsubstituted alkyl, for example optionally substituted, more preferably unsubstituted C 1-20 (For example, C 1-10 ) alkyl. 1 can be arranged to improve the compatibility of compound XX in the polymeric material into which it may be incorporated, for example by R 1 Relevant functional groups are included to improve compatibility.

[0035] One or each m is 0 or 1. Preferably, each m = 0. That is, except for the amine moiety and the amide moiety, each moiety (A) is unsubstituted.

[0036] Preferably, in compound XX, at least one moiety (AA) comprises an amine moiety (-NH2) ortho-bonded to an amide moiety (-CONH). Preferably, in each moiety (AA) in compound (XX), the amine moiety is ortho-bonded to the amide moiety. Preferably, in this case, m=0.

[0037] Preferably, the main segment does not include any cyclic or aromatic moieties.Preferably, the main segment includes a linear or branched chain.

[0038] The main fragment may comprise 3 to 20 carbon atoms. Preferably, it comprises 5 to 15 carbon atoms, more preferably 7 to 12 carbon atoms, and in particular 8 to 10 carbon atoms. When the number of carbon atoms is n, the number of hydrogen atoms may be equal to 2n-1. Preferably, the main fragment comprises 5 to 39 hydrogen atoms. Preferably, it comprises 9 to 29 hydrogen atoms, more preferably 13 to 23 hydrogen atoms and in particular 15 to 19 hydrogen atoms.

[0039] In a preferred embodiment, the major fragment is C9H 17 part.

[0040] The main fragment may comprise a linear chain comprising 6 to 14 carbon atoms, preferably 6 to 10 carbon atoms. The linear chain may comprise branching points to which chains comprising 1 to 4 carbon atoms are attached.

[0041] The main fragment may have the following general formula (BB)

[0042]

[0043] wherein p, q and r are integers, suitably in the range of 1 to 10, preferably in the range of 1 to 5. Preferably, p is in the range of 2 to 4, q is in the range of 1 to 3 and r is in the range of 2 to 6.

[0044] Preferably, the sum of the integers p, q and r is at least 4, preferably at least 6, more preferably at least 7. The sum may be less than 20, preferably less than 15, more preferably less than 10.

[0045] In compound XX, the nitrogen atoms of the amide moiety (-CONH) are preferably spaced at least 2 carbon atoms apart, preferably at least 4 carbon atoms apart; and suitably not more than 10 carbon atoms apart, for example not more than 7 carbon atoms apart.

[0046] The compound XX may have the formula

[0047]

[0048] wherein p, q and r are as described above.

[0049] The compound XX is preferably

[0050]

[0051] In a preferred embodiment of the compound of formula XXV, R 60 and R 61 independently represent a hydrogen atom or an unsubstituted alkyl or cycloalkyl group, and R 62 R independently represents a hydrogen atom or an unsubstituted alkyl or cycloalkyl group. In a particularly preferred embodiment, R 60 , R 61 , R 62 and R 63 Each represents a hydrogen atom.

[0052] The term "ppm" used herein refers to "parts per million" by weight.

[0053] The aldehyde scavenger may be part of a formulation that contacts the POM polymer. The formulation may be a liquid formulation or a solid formulation. The state of a material (eg, liquid) referred to herein refers to the state at standard temperature and pressure (STP).

[0054] The formulation may comprise at least 50 wt%, preferably at least 60 wt%, more preferably at least 70 wt%, especially at least 75 wt% of the carrier. The formulation may comprise less than 95 wt% of the carrier.

[0055] The formulation may include 50 wt% to 95 wt% of a carrier, 5 wt% to 50 wt% of the aldehyde scavenger and 0-30 wt% of other additives. The other additives may be selected from colorants, antioxidants, thickeners, process stabilizers, acid scavengers, lubricants and UV additives.

[0056] Preferably, in the formulation, the sum of the weight percentages of the carrier and the aldehyde scavenger is at least 80 wt%, at least 90 wt% or at least 95 wt%.

[0057] The formulation may be a solid masterbatch or a liquid formulation. When it is a solid masterbatch, it may contain 60-95 wt% of a thermoplastic polymer, such as polyoxymethylene (POM).

[0058] The formulation may include 10 wt% to 40 wt% of the aldehyde scavenger and 60 wt% to 90 wt% of a thermoplastic polymer, such as POM.

[0059] The solid masterbatch may include 0 to 10 wt%, preferably 0.5 wt% to 10 wt% of one or more antioxidants.

[0060] When the formulation is a liquid formulation, the formulation may comprise 50 wt % to 90 wt % (e.g., 50 wt % to 80 wt %) of a liquid carrier and 10 wt % to 50 wt % (e.g., 20 wt % to 50 wt %) of the aldehyde scavenger. The liquid carrier may be a liquid at STP. The carrier is suitably such that it has good solubility in the POM to be added. It may include oil (e.g., vegetable oil or mineral oil) or ethylene glycol.

[0061] Antioxidants have been found to act synergistically in the methods and when used in the methods, the antioxidants may be included in the formulation; or may also be in contact with the POM.

[0062] The method may include contacting the POM with an antioxidant. The ratio defined as the weight percent of aldehyde scavenger to the weight percent of antioxidant may be at least 1.0, preferably at least 3.0. The ratio may be less than 20.0, preferably less than 10.0.

[0063] When the formulation is used in the method and / or is in contact with POM in the method, the formulation may include 0 to 10 wt% of one or more antioxidants. The total weight percentage of antioxidants in the formulation may be in the range of 0 to 10 wt%, preferably in the range of 0.5 wt% to 10 wt% or 0.5 wt% to 7.0 wt%. The formulation preferably includes at least 1.0 wt% antioxidant.

[0064] The formulation may optionally include a phosphorus-containing antioxidant (eg, phosphite series compounds such as triphenyl phosphite, triphenyl phosphate series compounds such as tris(2,4-di-tert-butylphenyl)phosphate, diphosphonate series compounds, and metal salts of hypophosphorous acid).

[0065] The antioxidant may (and preferably does) include a sterically hindered phenolic compound. The antioxidant may include the following moieties:

[0066]

[0067] Where R 50 and R 51 R independently comprises at least four atoms, preferably selected from C, H, O and N atoms; more preferably selected from C and H atoms. 50 and R 51 Preferably it is saturated. 50 R may represent a tertiary alkyl moiety, for example a tertiary alkyl moiety comprising at least 4 carbon atoms. 50 Preferably represents a tert-butyl moiety. 51 Can represent C 1-4 Alkyl moieties, especially methyl.

[0068] The antioxidant may comprise at least two moieties XXX.

[0069] The antioxidant may include one or more oxyalkylene moieties, such as oxyethylene moieties.

[0070] The antioxidant may include one or more ester moieties.

[0071] The antioxidant preferably comprises only C, H and O atoms.

[0072] The antioxidant may have the following chemical formula

[0073]

[0074] Where L 50 is a linking moiety which suitably comprises the oxyalkylene moiety and one or more ester moieties. The antioxidant may be as follows:

[0075]

[0076] The method preferably reduces the aldehyde content in the POM polymer so that the POM polymer contains less than 2 ppm of aldehyde when evaluated according to VDA- 275. It also increases the OIT modestly.

[0077] According to a second aspect of the present invention, there is provided a use of the compound XX or cyanoacetamide of the first aspect for reducing the aldehyde (e.g. formaldehyde) content in a polyoxymethylene (POM) polymer and / or for increasing the oxidation induction time (OIT) in POM and / or improving the thermal stability of POM.

[0078] According to a third aspect of the present invention, there is provided a polyoxymethylene (POM) polymer having a reduced aldehyde content and / or an increased oxidative induction time (OIT) and / or improved thermal stability, wherein the POM polymer incorporates an aldehyde scavenger according to the first aspect or a reaction product between the aldehyde scavenger according to the first aspect and an aldehyde.

[0079] The POM polymer preferably comprises less than 2 ppm of aldehyde when evaluated according to VDA-275. The POM polymer suitably has improved thermal stability and / or increased OIT, which may be as described in Evaluation 3.

[0080] The POM polymer preferably comprises the residual carrier according to the first aspect.

[0081] The POM polymer preferably includes the antioxidant according to the first aspect.

[0082] The POM polymer may be in the form of particles.

[0083] The formulation can be used to make parts or to make particles (e.g. masterbatch particles), which can be used for subsequent part manufacturing. Therefore, according to a fourth aspect of the present invention, there is provided a method for making an article (e.g. a shaped article) or particles from a polyoxymethylene (POM) polymer, the method comprising:

[0084] (a) selecting a preparation comprising a carrier and the aldehyde scavenger according to the first aspect and / or the second aspect;

[0085] (b) contacting a POM polymer with the formulation; and

[0086] (c) forming the POM polymer into an article or particles, such as a shaped article.

[0087] The article or particle preferably comprises less than 2 ppm of aldehyde when assessed according to VDA-275. The article or particle polymer suitably has improved thermal stability and / or increased OIT, which may be as described in Assessment 3.

[0088] Preferably, in step (c) the POM polymer is suitably melt processed to define said article or particles.

[0089] The article or particle may be defined by any method known in the art. For example, the method may include injection molding, blow molding, thermoforming or extrusion.

[0090] The article or particle may include one or more colorants, and for example, when made into an article, may include 5ppm-500ppm of a colorant. Suitably, the above ppm is based on the amount of the POM polymer. The colorant described herein may be a dye or a pigment. When made into particles, the particles may include up to 60wt% of a colorant, such as titanium dioxide. Suitably, as previously described, such particles may define a masterbatch, which suitably includes 5wt% to 35wt% of a filler (e.g., a colorant).

[0091] Preferably, in the shaped article, the sum of the weight percentages of the one or more POM polymers and the aldehyde scavenger is at least 90 wt%, at least 95 wt% or at least 98 wt%.

[0092] According to a fifth aspect of the present invention, there is provided a product or particle having a reduced aldehyde content and / or improved thermal stability and / or increased OIT, wherein the product or particle is made as described in the fourth aspect and / or comprises a POM polymer and an aldehyde scavenger as described herein.

[0093] The article or particle preferably comprises less than 2 ppm of aldehyde when assessed according to VDA-275. The article or particle suitably has improved thermal stability and / or increased OIT, which may be as described in Assessment 3.

[0094] Any aspect of any invention described herein may be combined with any other aspect of any invention described herein mutatis mutandis. DETAILED DESCRIPTION

[0095] Specific embodiments of the present invention will now be described by way of example.

[0096] The following materials are described below:

[0097] 2-Cyanoacetamide - commercially available from Fisher Scientific;

[0098] Irganox 1010 - commercially available pentaerythritol tetrakis(3,5-di-tert-butyl-4-hydroxyhydrocinnamate) purchased from Sigma-Aldrich;

[0099] Vector A - refers to Clearslip available from ColorMatrix TM2. Carrier A is selected to have good solubility in the POM copolymer used.

[0100] POM copolymer - refers to Ultraform S2320 POM copolymer obtained from BASF;

[0101] Iupital POM-refers to Iupital TM F20-03 POM copolymer.

[0102] Assessment 1 - General Procedure for Determining Formaldehyde Content of Panels

[0103] The formaldehyde content of the samples was determined on injection molded plaques (40 x 100 x 3 mm (W x L x H)). TM (μ-CTE TM ) determines the formaldehyde content. The device is a versatile and compact unit with up to four small cylindrical chambers that allows sampling of chemicals released from products or materials. The released volatile and semi-volatile organic compounds (VOC and SVOC) are collected in a column containing 2,4-dinitrophenylhydrazine for analysis by HPLC according to ISO 16000-3. The formaldehyde reduction is calculated based on the percentage reduction in the formaldehyde content of the part containing the additive compared to a reference part without additive. The described evaluation has been shown to be comparable to VDA-275, a standard formaldehyde test for automobiles.

[0104] Evaluation 2 - Optical Performance Measurement Procedure

[0105] Plaques (dimensions 95 x 165 x 3 mm (W x L x H)) and related controls were prepared in a manner similar to that described below and the optical properties (i.e., L*, a*, and b*) were evaluated in transmission mode using a Minolta CM-3700d spectrophotometer equipped with a D65 / 10° illuminant.

[0106] polymer UltraformS2320 Machine Name Engel ES 330 / 70 HL Zone 3 temperature (℃) 190 Zone 2 temperature (℃) 190 Zone 1 temperature (℃) 190 Nozzle temperature (℃) 200 Mold temperature(℃) 50

[0107] Evaluation 3 - Oxidation Induction Time Test

[0108] Oxidation induction time (OIT) tests were performed using heat flux differential scanning calorimetry (DSC) to analyze the thermal stability of POM samples. About 5-6 mg of sample was heated from room temperature to 230°C under nitrogen flow (50 ml / min) and held for 5 minutes. The gas flow was switched to oxygen (50 ml / min) and kept constant to study the induction time. As discussed in "Oxidation induction time studies on the thermal degradation behavior ofpolyoxymethylene" by V. Archodoulaki, S. Lüftl and S. Seidler, Polymer Testing, Vol. 25, No. 1, 2006, pp. 83-90, the maximum peak of the OIT response was used as the OIT result instead of the onset temperature because it was observed that it was difficult to determine a clear onset temperature.

[0109] Example 1 - Acetaldehyde scavenger N,N'-(2-(4-(2-aminobenzamido)butyl)pentane-1,5-diyl)

[0110] Preparation of bis(2-aminobenzamide) (referred to as compound X)

[0111] Compound X has the following structure.

[0112]

[0113] 2H-Benzo[d][1,3]oxazine-2,4(1H)-dione (98.84 g, 3.5 Eq, 605.9 mmol) was dissolved in dimethylformamide (500 ml) at room temperature. A solution of 4-(aminomethyl)octane-1,8-diamine (30.00 g, 1 Eq, 173.1 mmol) in dimethylformamide (250 ml) was added dropwise to the reaction mixture. The reaction mixture was stirred overnight at room temperature until LC-MS confirmed complete conversion. The dimethylformamide was removed under reduced pressure to give a dark brown oil. Water (1 liter), ammonium hydroxide (25%, 50 ml) were added thereto, and the product was extracted with dichloromethane. The dichloromethane was removed under reduced pressure, and the product was recrystallized in a mixture of methanol and acetonitrile. The solid was collected by filtration and dried to give N,N'-(2-(4-(2-aminobenzamido)butyl)pentane-1,5-diyl)bis(2-aminobenzamide) (51.0 g, yield 55.5%). The structure of the compound was confirmed by NMR and LC-MS, and the melting point was 160°C.

[0114] Example 2 - General steps for preparing solid dosage forms

[0115] Solid masterbatch formulations were prepared by mixing the required amounts of base polymer, formaldehyde reducing agent and optional antioxidant stabilizer in a twin screw extruder. Pellets were cut using a strand cutter. The material was prepared using a Labtech LTE444-16 twin screw extruder under the following conditions:

[0116] Screw speed (rpm) 300 Feed rate (kg / h) 3 Screw ratio 44:1 Zone 1(℃) 80 Zone 2(℃) 175 Zone 3(℃) 190 Zone 4 (℃) 200 Zone 5(℃) 200 Zone 6 (℃) 200 Zone 7(℃) 200 Zone 8 (℃) 185 Zone 9(℃) 180 Zone 10(℃) 190

[0117] Example 3 - General steps for preparing liquid formulations

[0118] The liquid formulation is prepared by mixing the liquid carrier A and the optional dispersant (Solplus K240 (poly(12-hydroxystearic acid)-polyethyleneimine copolymer; CAS No. 124578-12-7) in a liquid mixing vessel. An aldehyde scavenger and an optional antioxidant are added thereto. The formulation may be milled to produce the desired particle size. A rheology modifier may be optionally added. The formulation is mixed under vacuum to remove any entrapped air.

[0119] Example 4-2-Oxidation Induction Time (OIT) Test of Cyanoacetamide and Compound X Preparations and Comparison with Prior Art Comparison of formaldehyde scavengers for POM

[0120] The technology established in the prior art was extruded in lupital polyoxymethylene and compared with the use of 4-cyanoacetamide and compound X in terms of formaldehyde emission and OIT. In each case the antioxidant (Irganox 1010) was fixed at 0.3%. The results are shown in the table below.

[0121]

[0122] The results show that the individual use of Compound X and 2-cyanoacetamide resulted in very low formaldehyde emissions from POM with high OIT. It should be noted that cyanoacetamide provided high levels of formaldehyde reduction compared to other scavengers with only 50% addition. Furthermore, it is well known that OIT is correlated with the concentration of antioxidants present in the POM polymer. A synergistic benefit was observed for the combination of Compound X or cyanoacetamide with antioxidants.

[0123] From the foregoing it can be concluded that both Compound X and cyanoacetamide provide improvements and / or have advantages over the cited prior art.

[0124] Example 5 - Preparation of solid and liquid formulations containing Compound X

[0125] Following the procedures described in Examples 2 and 3, solid and liquid formulations containing Compound X were prepared, the compositions of which are shown in the following table.

[0126] Hereinafter, the aldehyde scavenger (AS) component is Compound X, the antioxidant is Irganox 1010, the liquid carrier of Formulation VIII is Carrier A, and the solid carrier of Formulation VII is POM copolymer.

[0127]

[0128] Examples 6 and 7 - Evaluation of Solid and Liquid Formulations Containing Compound X

[0129] Solid and liquid formulations VII and VIII were added to Ultraform S2320POM copolymer and plaques produced by injection molding with the let-down-ratios (LDR) shown in the table below. Formaldehyde emission was evaluated as described in Evaluation 1, and L*, a*(D65), b*(D65) were evaluated as described in Evaluation 2.

[0130]

[0131] The control refers to the POM copolymer without additives.

[0132] Both the solid masterbatch and liquid formulations provided significant formaldehyde reduction while reducing discoloration at low addition levels. In addition, no significant differences in oxidative induction time were observed between the formulation selections - as described in Example 4, both had a favorable impact on OIT.

[0133] Example 8 - Preparation of solid and liquid formulations containing 2-cyanoacetamide

[0134] Following the procedures described in Examples 2 and 3, solid and liquid formulations containing cyanoacetamide were prepared with the compositions shown in the following table. In the following, the aldehyde scavenger (AS) component is 2-cyanoacetamide, the antioxidant is Irganox 1010, the liquid carrier of Formulation X is Carrier A, and the solid carrier of Formulation IX is POM copolymer.

[0135]

[0136] Examples 9 and 10 - Evaluation of solid and liquid formulations containing 2-cyanoacetamide

[0137] Solid and liquid formulations IX and X were added to Ultraform S2320-POM copolymers and plaques produced by injection molding with the following LDRs. Formaldehyde emission was evaluated as described in Evaluation 1, and L*, a*(D65), b*(D65) were evaluated as described in Evaluation 2.

[0138]

[0139] The control refers to the POM copolymer without additives.

[0140] Both the solid masterbatch and liquid formulations provided significant formaldehyde reduction while reducing discoloration at low addition levels. In addition, no significant differences in oxidative induction time were observed between the formulation selections - as described in Example 4, both had a favorable impact on OIT.

[0141] Examples 11 to 15 - Use of Compound X as an aldehyde scavenger and synergistic effects of formulation components on formaldehyde release

[0142] The individual components or component mixtures contained in the liquid formulations were added to the POM copolymers at the indicated levels following the procedures generally described in Examples 6 and 7 and then evaluated to determine the individual and / or collective effects on formaldehyde emission and optical properties. The details of the components and mixtures were evaluated and the results are provided in the following table.

[0143] In the case where a carrier and an antioxidant were used, the components were carrier A and Irganox 1010, respectively.

[0144]

[0145] Examples 16 to 20 - Use of cyanoacetamide as an aldehyde scavenger and synergistic effects of formulation components on formaldehyde release ring

[0146] The individual components or component mixtures contained in the liquid formulations were added to the POM copolymers at the indicated levels following the procedures generally described in Examples 6 and 7 and then evaluated to determine the individual and / or collective effects on formaldehyde emission and optical properties. Details of the components and mixtures were evaluated and the results are provided in the following table.

[0147] In the case where a carrier and an antioxidant were used, the components were carrier A and Irganox 1010, respectively.

[0148]

[0149] For POM preparations, a variety of materials can be added to the preparations, including stabilizers such as hindered amine light stabilizers (HALS); acid scavengers such as calcium stearate and hydrotalcite; lubricants such as wax; BaSO4; TiO2; carbon black; pigments; aromatic polyamides; silica powder; polytetrafluoroethylene and UV stabilizers.

[0150] The invention is not limited to the details of the foregoing embodiments. The invention extends to any novel feature or any novel combination of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel step or any novel combination of the steps of any method or process disclosed in this specification (including any accompanying claims, abstract and drawings).

Claims

1. A method for reducing the aldehyde content and / or increasing the oxidative induction time (OIT) and / or improving the thermal stability in a polyoxymethylene (POM) polymer, the method comprising the step of contacting the POM polymer or a monomer, oligomer or prepolymer involved in the preparation of the POM polymer with an aldehyde scavenger selected from the following: (i) a compound XX comprising at least three moieties (AA) of the formula wherein each moiety (AA) comprises an amine moiety (-NH2) bonded ortho or meta to an amide moiety (-CONH); Each R 1 independently represents a substituent, and m is an integer from 0 to 4; and wherein the three moieties (AA) are bonded via their respective amide nitrogen atoms to respective carbon atoms of a main fragment, wherein the main fragment comprises only carbon and hydrogen atoms and is saturated; and (ii) Cyanoacetamide. 2 . The method according to claim 1 , wherein the POM is a POM homopolymer or a POM copolymer.

3. The method according to claim 1 or 2, wherein: One R 1 or each R 1 is optionally substituted, preferably unsubstituted alkyl; One m or each m is 0 or 1; at least one moiety (AA) comprises an amine moiety (-NH2) ortho-bonded to an amide moiety (-CONH); The main fragment does not include any cyclic or aromatic moieties; and The main fragment includes a linear chain or a branched chain.

4. The method according to any of the preceding claims, wherein the main fragment has the following general formula (BB): wherein p, q and r are integers, suitably in the range of 1 to 10, preferably in the range of 1 to 5.

5. The method according to claim 4, wherein the compound XX has the following formula:

6. A process according to any preceding claim, wherein the cyanoacetamide has the general formula XXV Where R 60 and R 61 independently represents a hydrogen atom or an optionally substituted, preferably unsubstituted, alkyl, cycloalkyl or aryl group.

7. The method according to claim 6, wherein R 62 and R 63independently represents a hydrogen atom or an optionally substituted, preferably unsubstituted, alkyl, cycloalkyl or aryl group.

8. The method according to claim 6 or 7, wherein R 60 and R 61 independently represent a hydrogen atom or an unsubstituted alkyl or cycloalkyl group, and R 62 independently represents a hydrogen atom or an unsubstituted alkyl or cycloalkyl group.

9. The method according to any one of claims 6 to 8, wherein R 60 , R 61 , R 62 and R 63 Each represents a hydrogen atom.

10. The method according to any of the preceding claims, wherein the aldehyde scavenger is part of a formulation contacted with the POM polymer, wherein the formulation is selected from: A solid masterbatch formulation, wherein the formulation comprises 10 wt% to 40 wt% of the aldehyde scavenger and 60 wt% to 90 wt% of a thermoplastic polymer, such as POM; and A liquid formulation comprising 50 wt % to 90 wt %, such as 50 wt % to 80 wt % of a liquid carrier and 10 wt % to 50 wt %, such as 20 wt % to 50 wt % of the aldehyde scavenger.

11. The method of claim 10, wherein the formulation comprises 0.5 wt% to 10 wt% of an antioxidant.

12. The method of claim 11, wherein the antioxidant comprises a sterically hindered phenolic compound.

13. The method of claim 11 or 12, wherein the antioxidant has the formula: Where L 50 is a linking moiety that includes an oxyalkylene moiety and one or more ester moieties.

14. The method according to any of the preceding claims, wherein the method reduces the aldehyde content in the POM polymer so that the POM polymer contains less than 2 ppm of aldehydes when evaluated according to VDA-275.

15. A method according to any preceding claim, which is a method of increasing the oxidation induction time (OIT).

16. Use of compound XX or the cyanoacetamide according to any of the preceding claims for reducing the aldehyde content, such as formaldehyde, in polyoxymethylene (POM) polymers and / or for increasing the oxidation induction time (OIT) in POM and / or improving the thermal stability of POM.

17. A polyoxymethylene (POM) polymer having reduced aldehyde content and / or increased oxidative induction time (OIT) and / or improved thermal stability, the POM polymer incorporating an aldehyde scavenger according to any preceding claim, or a product of a reaction between an aldehyde scavenger according to any preceding claim and an aldehyde.

18. The polymer of claim 17, wherein the POM polymer contains less than 2 ppm of aldehydes when evaluated according to VDA-275.

19. The polymer according to claim 17 or 18, wherein the POM polymer is in the form of particles.

20. A method of preparing an article or pellets from a polyoxymethylene (POM) polymer, such as a shaped article, comprising: (a) selecting a formulation comprising a carrier and an aldehyde scavenger according to any one of the preceding claims; (b) contacting a POM polymer with the formulation; and (c) forming the POM polymer into an article or particles, such as a shaped article.

21. The method of claim 20, wherein the article or particle comprises less than 2 ppm of aldehydes when evaluated according to VDA-275.

22. The method of claim 20 or 21, wherein the article or particle has improved thermal stability and / or increased OIT.

23. An article or particle having reduced aldehyde content and / or improved thermal stability and / or increased OIT, said article or particle being made according to the method of any one of claims 20 to 22.

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