JPH0649321A - Polyoxymethylene composition - Google Patents

Abstract

PURPOSE:To obtain a polyoxymethylene compsn. improved in sliding properties on metal, thermal stability, etc., by compounding a polyoxymethylene resin with specified amts. of a hindered phenol antioxidant, a specific aliph. ether, and a melamine-formaldehyde addition-polycondensate. CONSTITUTION:A polyoxymethylene resin is compounded with 0.01-5wt.% hindered phenol antioxidant, 0.05-5wt.% aliph. ether of formula I and/or polyhydric alcohol-derived aliph. ether of formula II (wherein R<1> and R<2> are each 8C or higher alkyl provided that 1-3 hydrogen atoms of them may be substd. by hydroxyl groups; X is a residue of a 2-12C di- to hexahydric alcohol; and n is 1-6), and 0.01-10wt.% melamine-formaldehyde addition-polycondensate to give the objective compsn., which has good sliding properties on a metal wire and hardly stains a metal mold even in a long-term continuous molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyoxymethylene having improved generation and discoloration of mold deposits while maintaining good slidability with respect to a metal represented by sliding with a metal wire. It relates to a composition.

[0002]

BACKGROUND OF THE INVENTION As is well known, polyoxymethylene resins are excellent in physical properties such as mechanical properties and electrical properties, or in chemical properties such as chemical resistance and heat resistance. In recent years, it has been used as a typical engineering resin in an extremely wide range of fields. However, with the expansion of the fields in which polyoxymethylene resins are used, the properties required for the materials have been subdivided in various ways. One of such properties is slidability. In other words, in the field of household electrical products such as audio and video, software such as tape cassettes, various gears, cams, levers, bearings, etc. used in automobile power transmission components, friction heat (temperature 1) It is important to prevent the transmission torque from being reduced, thermal deformation, contamination of the system due to wear powder and the induction of malfunction, and to prevent abnormal noise and vibration caused by friction and wear.
Can be said to be one. Conventionally, these problems have generally been avoided by, for example, applying grease to parts. However, as labor saving has progressed in recent years, there has been a demand for polyoxymethylene resins with better slidability in order to eliminate the process of grease application, and by blending various oils such as silicone oil and paraffin oil, the material itself There are many proposals and ideas to improve the slidability of. Among these conventionally proposed methods, particularly in sliding with a metal wire, one of the most severe fields for the slidability of the material, because the frictional resistance is greater than in other fields, A material having sufficient slidability has not been obtained, and its improvement has been strongly desired. In addition, in general, a composition containing oil or the like has a poor moldability, in particular, the bite into the screw is poor, so that the measuring time (molding cycle) is lengthened, formaldehyde gas is generated, and stabilizers and various oils are transferred to the mold. Mold deposit (MD)
And the problem of discoloration during processing such as extrusion and molding, and at the same time, improvement thereof has been desired.

[0003]

Means for Solving the Problems As a result of detailed investigations on a sliding agent and a stabilizer, the present inventors have found that
(I) an ether of aliphatic alcohols having 8 or more carbon atoms and / or a polyhydric alcohol having 2 to 6 carbon atoms and 2 to 6 hydroxyl groups as shown in general formula (II) And an ether synthesized from a higher aliphatic alcohol having 8 or more carbon atoms and / or a higher aliphatic epoxide, together with an antioxidant and a melamine-formaldehyde polycondensate, in a polyoxymethylene composition. The inventors have found that the object is achieved and have completed the present invention. That is, the present invention relates to a total composition of 0.01 to 5% by weight of a hindered phenolic antioxidant and 0.05 to 5% by weight.
An aliphatic ether represented by the general formula (I) and / or a polyhydric alcohol aliphatic ether represented by the general formula (II),
And 0.01 to 10% by weight of a melamine-formaldehyde polycondensate, which is a polyoxymethylene composition. (I) R ¹ -OR ² (II) (R ¹ -O) _n -X [wherein R ¹ _and R ² are saturated or unsaturated alkyl groups having 8 or more carbon atoms, Hydrogen may be replaced by a hydroxyl group, and R ¹ = R ² may be satisfied. X is a residue of a polyhydric alcohol having 2 to 12 carbon atoms and 2 to 6 hydroxyl groups. n is an integer of 1-6. The constituent components of the composition of the present invention will be described in detail below.

The aliphatic ether represented by the general formula (I) used in the present invention is derived from at least one saturated or unsaturated aliphatic alcohol or epoxide containing 8 or more carbon atoms. Is. The polyhydric alcohol-based aliphatic ether represented by the general formula (II) means at least one saturated or unsaturated aliphatic alcohol or epoxide containing 8 or more carbon atoms and carbon. It is derived from a polyhydric alcohol having a number of 2 to 12 and 2 to 6 hydroxyl groups. Examples of the higher aliphatic alcohol having 8 or more carbon atoms, preferably 32 or less carbon atoms, used for preparing these aliphatic ether (I) or polyhydric alcohol aliphatic ether (II) include octyl alcohol and nonyl alcohol. , Decyl alcohol,
Undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, palmityl alcohol, heptadecyl alcohol, stearyl alcohol, nonadecyl alcohol,
One or more selected from arachidyl alcohol, behenyl alcohol, montanyl alcohol, lignoceryl alcohol, myristoyl alcohol, palmitoleyl alcohol, oleyl alcohol, linole alcohol, linolenyl alcohol, ricinol alcohol, 12 hydroxystearyl alcohol, And naturally occurring fatty alcohols or mixtures thereof containing such ingredients. Further, as the aliphatic epoxide,
Among octyl epoxide, nonyl epoxide, decyl epoxide, undecyl epoxide, lauryl epoxide, tridecyl epoxide, myristyl epoxide, pentadecyl epoxide, palmityl epoxide, heptadecyl epoxide, stearyl epoxide, nonadecyl epoxide, arachidyl epoxide, behenyl epoxide One or more selected from the above or a mixture thereof. or,
As the polyhydric alcohol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butanediol, pentanediol, hexanediol, glycerin, diglycerin, triglycerin, tetraglycerin, threitol, erythritol, pentaerythritol, It is at least one selected from dipentaerythritol, arabitol, ribitol, xylitol, sorbite, sorbitan, sorbitol, and mannitol. Of these aliphatic ether compounds, preferably,
Ether compound derived from one or more selected from lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, behenyl alcohol, octyl epoxide, decyl epoxide, lauryl epoxide, myristyl epoxide, palmityl epoxide, stearyl epoxide, or the above-mentioned fat It is an ether compound derived from one or more group alcohols or aliphatic epoxides and a polyhydric alcohol selected from ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, glycerin and diglycerin. Particularly preferred compounds are those having at least one hydroxyl group in the molecule, specifically, glycerin monopalmityl ether, glycerin dipalmityl ether, glycerin monostearyl ether,
Glycerin distearyl ether, glycerin monobehenyl ether, glycerin dibehenyl ether, diglycerin monopalmityl ether, diglycerin dipalmityl ether, diglycerin monostearyl ether,
Diglycerin distearyl ether, diglycerin monobehenyl ether, diglycerin dibehenyl ether,
2-hydroxydecyl palmityl ether, 2-hydroxy palmityl palmityl ether, 2-hydroxy decyl stearyl ether, 2-hydroxy palmityl stearyl ether, 2-hydroxy stearyl stearyl ether, ethylene glycol mono 2-hydroxy palmityl ether, ethylene Glycol mono 2-hydroxy stearyl ether, diethylene glycol mono palmityl ether, diethylene glycol mono stearyl ether, diethylene glycol mono 2-hydroxy palmityl ether, diethylene glycol mono 2-hydroxy stearyl ether, triethylene glycol mono palmityl ether, triethylene glycol mono stearyl ether , Triethylene glycol mono 2-
Hydroxy palmityl ether, triethylene glycol mono 2-hydroxy stearyl ether, propylene glycol mono 2-hydroxy palmityl ether, propylene glycol mono 2-hydroxy stearyl ether, dipropylene glycol mono palmityl ether, dipropylene glycol mono stearyl ether,
Although it is dipropylene glycol mono-2-hydroxypalmityl ether, it may be a mixture of two or more selected from these. The amount in the polyoxymethylene composition of the present invention is 0.05 to 5% by weight, preferably
0.1 to 3% by weight, particularly 0.15 to 1% by weight are preferred. If the blending amount is less than 0.05% by weight, the slidability is not improved and the mold deposit is not reduced. If the blending amount exceeds 5% by weight, the screw biting property at the time of molding is deteriorated and the molding cycle is increased. Causes the problem. Further, when the number of hydroxyl groups in the polyhydric alcohol exceeds 6, the balance between hydrophobicity and hydrophilicity as an ether compound tends to be hydrophilic, so that the hydrolysis of the ether compound is likely to occur and the performance as an oil deteriorates. It is not preferable because

By blending such an aliphatic ether compound, the aliphatic ether compound does not permeate between the twisted wires of the metal itself on the sliding surface with the metal wire and is structurally stable in a wide temperature and humidity range. Therefore, it is presumed that good slidability will be maintained for a long period of time. Further, by blending such an aliphatic ether in combination with a hindered phenolic antioxidant or a melamine-formaldehyde polycondensate, it is possible to suppress the decomposition of polyoxymethylene or to decompose it and to capture the generated formaldehyde. The generation of decomposition gas at the time of molding is suppressed as much as possible, and since it itself has poor affinity with metals and has almost no decomposition property, it is assumed that almost no metal deposits are formed and discoloration hardly occurs. To be done.

Next, as hindered phenolic antioxidants used in the present invention, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 1,6-
Hexanediol bis [3- (3,5-di-t-butyl-
4-hydroxyphenyl) propionate], pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol bis [3- (3-t-butyl-5-methyl) -4-Hydroxyphenyl) propionate], 1,
3,5-Trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, n-octadecyl-3- (4'-hydroxy-3 ', 5'-di -T-butylphenol) propionate, 4,4'-methylenebis (2,6-di-t-butylphenol), 4,4'-butylidenebis (3-methyl-6-t-butylphenol), distearyl-3,5- Di-t-butyl-4-hydroxybenzylphosphonate, 2-t-butyl-6- (3-t-
Butyl-5-methyl-2-hydroxybenzyl) -4-
At least one kind or two or more kinds of methylphenyl acrylate and N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide) can be used. 6-hexanediol bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate ], Triethylene glycol bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy) -Hydrocinnamamide) is a particularly preferred substance.The amount of the hindered phenolic antioxidant added and blended in the present invention is 0.01 to 5 in the composition. Amount%, preferably 0.05
3% by weight, especially 0.10 to 1% by weight, are preferred. If the amount is less than 0.01% by weight, it is not sufficient to improve the thermal stability of the polyoxymethylene resin composition, and if it exceeds 5% by weight, the effect of thermal stability reaches saturation and rather a tendency to discolor occurs. Absent.

Next, the melamine-formaldehyde polycondensate used in the present invention has a melamine: formaldehyde molar ratio of 1: 0.8 to 1: 6.0, preferably 1: 1.0 to 1: 3.
Is manufactured to have 0, and further, C _{1 to} C ₄
-Alkanol may be partially etherified such that the molar ratio of melamine: ether group is 1: 6.0 or less, preferably 1: 1.0 or less. Further, the melamine-formaldehyde polycondensate used in the present invention can be produced by various known methods. For example, melamine is added to a formaldehyde aqueous solution adjusted to pH 8 to 9, the temperature is maintained at 60 to 90 ° C, and the mixture is dissolved and reacted with stirring. Since the solution becomes cloudy as the reaction proceeds, the condensation reaction is stopped by cooling for an appropriate time. This is dried by a method such as spray drying to obtain a melamine-formaldehyde polycondensate powder. Its amount in the polyoxymethylene composition according to the invention is 0.01 to 10% by weight, preferably 0.05.
-3% by weight, particularly 0.10-1% by weight are preferred. If the amount is less than 0.01% by weight, it is not sufficient to improve the thermal stability of the polyoxymethylene resin composition, and if it exceeds 10% by weight, the mechanical properties of the material are significantly impaired and the composition becomes brittle. .

The polyoxymethylene to which the above-mentioned additives are added is a polymer compound having an oxymethylene group (--CH ₂ O--) as a main constituent unit, and other than polyoxymethylene homopolymer and oxymethylene group. It may be any of copolymers, terpolymers and block copolymers containing a small amount of other constitutional units, and the molecule is not only linear but branched.
It may have a crosslinked structure. Moreover, there is no particular limitation regarding the degree of polymerization and the like.

The composition of the present invention is not essential, but depending on the purpose thereof, other than the aliphatic ether compound represented by the general formula (I) or (II) of the present application, paraffin which is a conventionally known sliding agent can be used. One or more types of oils, silicone oils, aliphatic ester oils, fluorine oils (represented by PTFE oligomers), polyalkylene glycols, and mineral oils can be used in combination. Further, one or more nitrogen-containing compounds other than the melamine-formaldehyde polycondensate of the present application, one or more metal-containing compounds such as alkali or alkaline earth metal or zinc oxides, hydroxides, inorganic acid salts, carboxylates or alkoxides are used in combination. You can also do it. Here, the nitrogen-containing compound means nylon 12, nylon 6/10, nylon 6/66/61.
Polyamides such as homo- or copolymerized polyamides such as 0, substituted polyamides having a methylol group, etc., nylon salts, synthetic with caprolactam, or caprolactone, polyesteramides synthesized from a combination with caprolactam, polyaminotriazole, dicarboxylic acid dihydrazide, A heat-condensate synthesized by heating from urea, a nitrogen-containing condensation polymer synthesized from urea and a diamine,
Examples thereof include a urea heat condensate synthesized by heating urea, a polycondensate of cyanoguanidines and formaldehyde, a polycondensate of guanamines and formaldehyde, and the like. Examples of the metal-containing compound include hydroxides, carbonates, phosphates, silicates, borates, oxalates, malonates, succinates, adipine of sodium, potassium, magnesium, calcium or barium. salts, such as salts of substituted higher fatty acids having such higher (C ₁₀ ~ ₃₂₎ fatty acids and substituents such as hydroxyl stearic acid. Furthermore, basic compounds containing at least one tertiary nitrogen atom and a metal of a carboxylic acid in the same group, for example, N-methylimino sodium diacetate, nitrilo 3 acetic acid 3 sodium, ethylenediamine 4 acetic acid 4 sodium, ethylenediamine 4
Acetic acid 4 potassium, ethylenediamine tetraacetic acid 2 calcium, diethylenetriamine 5 acetic acid 5 sodium, diethylenetriamine 5 acetic acid 5 potassium, triethylenetetramine 6 acetic acid 6 sodium, ethylenedioxybis (ethylamine) -N, N, N ', N'-4 acetic acid 4 sodium etc. are mentioned. Further, in order to impart desired properties to the composition of the present invention depending on its purpose, conventionally known additives such as lubricants, nucleating agents, releasing agents, antistatic agents, other surfactants,
Alternatively, one or more organic fibrous, powdery, or plate-like fillers may be added and contained.

The method for preparing the composition of the present invention is not particularly limited, and can be easily prepared by the known equipment and method generally used as a conventional resin composition preparation method. For example,
i) After mixing each component, kneading and extruding with an extruder to prepare pellets, and then molding, ii) once mixing a predetermined amount of pellets having different compositions and subjecting to molding, and after molding, a molded product of the desired composition And iii) a method of directly charging one or more components of each component into a molding machine, and the like. In addition, mixing a part of the resin component in the form of fine powder with the other components and adding the powder is a preferable method for uniformly blending these components.

[0011]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. still,
The evaluation method shown in the following examples is as follows. 1) Sliding property A round plate (7 × 7) wire with a rope diameter of 1 mm is attached to a circular plate (radius 10 mm, thickness 4 mm) with a radius of 1 mm formed from a sample pellet, and the circumference of the disk is rounded. Multiply so that it touches 1/4 of the surface. The wire and the sample sample are slid for 6 hours by alternately drawing a constant load from both ends of the trolley wire. After that, the load applied to the other when pulled from one side was detected by the load cell, and what percentage of the load applied to the wire was calculated to evaluate the frictional characteristics. 2) Thermal stability The weight loss when the sample pellet was left at 235 ° C for 45 minutes was measured, and the weight loss rate at that time was calculated. 3) Moldability Amount of deposit on mold A specific molded product was continuously molded (about 24 hours) from the sample polyoxymethylene composition using an injection molding machine, and the amount of deposit on the mold was evaluated. That is, the stains on the mold during continuous molding were evaluated by visual observation in five levels. (Molding conditions) Injection molding machine: Nissei ps20E (manufactured by Nissei Plastic Industry Co., Ltd.) Cylinder temperature: 200 ° C Injection pressure: 750kg / cm ² Injection time: 4sec Cooling time: 4sec Mold temperature: 30 ° C Pellet biteability Weighing position 2 using Toshiba IS22EPN under the following conditions.
The time required for weighing was measured from 2 to 4 cm to obtain the weighing time of the unit screw moving distance. Measurement conditions: Cylinder temperature setting 190 ° C. Screw rotation speed 80 rpm Examples 1 to 8 Polyoxymethylene copolymers (DURACON manufactured by Polyplastics Co., Ltd.) were added with hindered phenolic antioxidants and fats shown in Table 1. The above-mentioned evaluation was performed by adding and mixing the group ether compound and the melamine-formaldehyde polycondensate in the proportions shown in Table 1 to obtain a pelletized composition with an extruder. The results are shown in Table 1.

Comparative Examples 1 to 9 As shown in Table 2, when the melamine-formaldehyde polycondensate is not blended and the blending amount of the aliphatic ether compound is out of the range of the present invention, the melamine-formaldehyde polycondensate is used instead of the melamine-formaldehyde polycondensate. When cyanoguanidine or 12-nylon was blended and various sliding agents were blended instead of the aliphatic ether compound, pelletized compositions were obtained in the same manner as in Examples 1 to 8 and the above evaluation was performed. The results are shown in Table 2.

[0013]

[Table 1]

[0014]

[Table 2]

Note-1 Antioxidant a-1: triethylene glycol-bis [3- (3-t-
Butyl-5-methyl-4-hydroxyphenyl) propionate] a-2: pentaerythritol tetrakis [3- (3,5
-Di-t-butyl-4-hydroxyphenyl) propionate] Note-2 Aliphatic ether b-1: Glycerin monostearyl ether b-2: Glycerin mono (2-hydroxydecyl) ether b-3: Triethylene glycol dodecyl ether b-4: Distearyl ether Note-3 Other oils b'-1: Silicone oil b'-2: Triethylene glycol b'-3: Stearyl alcohol b'-4: Stearyl stearate Note-4 Melamine-formaldehyde Condensate c-1: Melamine prepared with a feed composition having a formaldehyde / melamine ratio of 1 / 1-Formaldehyde polycondensate c-1: Melamine prepared with a feed composition having a formaldehyde / melamine ratio of 2/1 Formaldehyde polycondensate Note-5 Other nitrogen-containing compounds c'-1: Cyanoguanidine c'-2: 12- Nylon

[0016]

As is apparent from the above description and Examples, the polyoxymethylene composition of the present invention has extremely good slidability with respect to a metal as represented by sliding with a metal wire. In addition, the thermal stability is remarkably improved as compared with the conventional one. With respect to its moldability, the mold is less contaminated even during continuous molding for a long period of time, and the bite of the screw during molding is significantly better than in the past.

Claims (5)

[Claims] 1. The total composition, 0.01 to 5% by weight of a hindered phenolic antioxidant, and 0.05 to 5% by weight of an aliphatic ether represented by the general formula (I) and / or general formula
(II) a polyhydric alcohol-based aliphatic ether, and
A polyoxymethylene composition comprising 0.01 to 10% by weight of a melamine-formaldehyde polycondensate. (I) R ¹ -OR ² (II) (R ¹ -O) _n -X [wherein R ¹ _and R ² are saturated or unsaturated alkyl groups having 8 or more carbon atoms, Hydrogen may be replaced by a hydroxyl group, and R ¹ = R ² may be satisfied. X is a residue of a polyhydric alcohol having 2 to 12 carbon atoms and 2 to 6 hydroxyl groups. n is an integer of 1-6. ] 2. The polyoxymethylene composition according to claim 1, wherein the aliphatic ether represented by the general formula (I) or (II) has at least one hydroxyl group. 3. The polyhydric alcohol which is a constituent component of the polyhydric alcohol-based aliphatic ether represented by the general formula (II) is ethylene glycol, propylene glycol, glycerin or a dimer or tetramer thereof. The polyoxymethylene composition according to 1 or 2. 4. The melamine-formaldehyde polycondensate has a melamine: formaldehyde molar ratio of 1: 0.8-.
The polyoxymethylene composition according to any one of claims 1 to 3, which is a melamine-formaldehyde polycondensate produced to have a ratio of 1: 6.0. 5. A melamine, which is a monomer of a melamine-formaldehyde polycondensate, is a C ₁ -C ₄ -alkanol,
The polyoxymethylene composition according to any one of claims 1 to 4, wherein the polyoxymethylene composition is partially etherified such that the molar ratio of melamine: ether group is 1: 0.01 to 1: 6.0.