KR20010002077A - Composition of poly(oxymethylene) - Google Patents

Abstract

PURPOSE: The titled resin composition improved impact resistance and mechanical strength by adding a polyether-ester copolymer to polyoxymethylene resin and then adding a neoalkoxy titanate or neoalkoxy zirconate compound thereto is provided, which can be used as power transfer material. CONSTITUTION: This composition comprises 100 parts by weight of polyoxymethylene resin, 10 to 60 parts by weight of polyether-ester block copolymer and 0.05 to 5 parts by weight of a neoalkoxy titanate or neoalkoxy zirconate compound of formula 1. In formula, M is titanium or zirconium; R R1 and R2 are the same or different C1-20 alkyl, alkenyl, alkynyl, aryl or alkalyl or halogen or ether substituted derivatives, additionally R2 is oxy derivatives or ether substituted oxy derivatives thereof; A, B and C are athoxy(ArO-), thioathoxy (ArS-), satisfyz+y+z = 3. The composition show characteristics of an impact resistance of more than 30 kg.cm/cm, a tensile strength of more than 550 kg/cm2, a coefficient of kinetic friction of less than 0.2 and abrasion loss of less than 1.

Description

Polyoxymethylene resin composition {Composition of poly (oxymethylene)}

The present invention relates to a polyoxymethylene resin composition, and more particularly has a high wettability characteristics having a level that can be used as a material for gears and bearings, impact strength and frictional wear resistance characteristics while maintaining the mechanical strength of the POM itself It is related with the polyoxymethylene resin composition which improved this.

Polyoxymethylene (hereinafter referred to as POM) is widely used as an engineering resin because of its excellent mechanical properties, chemical properties such as chemical resistance and heat resistance. However, there is a disadvantage in that the degree of crystallinity is higher than that of other resins and has a hard property.

In order to improve the brittle nature of POM, a method of adding an impact modifier has been studied. Particularly, since POM does not have a reactive group, studies are being actively conducted to increase compatibility with an impact modifier.

In addition, POM has a self-lubricating property has an advantage of excellent wear resistance, but the wear resistance is insufficient due to insufficient wear resistance according to the use of the self-lubricating properties are required.

Looking at the required characteristic in more detail, the POM itself satisfies a certain degree of physical properties for the application of gears and bearings such as power transmission, but there is a problem that the sharp peak of the gear products are easily damaged during operation.

To compensate for this, toughness is required. According to various experimental results, impact strength should be about 30kg · cm / cm. In general, POM material having impact strength of 30kg · cm / cm has a tensile strength of 400kg. Insufficient stiffness at the level of / cm 2, which causes a lot of stress during driving of gears, which shortens the life of the product.In addition, the wear resistance is not high, the coefficient of dynamic friction is high. Therefore, it is not possible to use the product as the friction-wear material easily to the end of its life.

In order to apply power transmission materials such as gears, tensile strength is 500kg / ㎠, impact strength is 30kg · cm / cm, dynamic friction coefficient should be at least 0.2 level and wear level should be 1 level. It can be applied without any problem.

As an example of the method of providing impact resistance to a conventional POM, the method of mixing a hydrocarbon rubber containing a nitrile group or a carboxylic acid ester group in a side chain (JP-45-45647), (alpha) -olefin / (alpha), (beta)-unsaturated A method of mixing a copolymer of carboxylic acid (JP-45-18023), A method of mixing a copolymer of ethylene / vinyl or acrylic ester (JP-45-26231), a diolefin / acrylonitrile copolymer, That is, a method of improving impact strength and flexural modulus by mixing a copolymer in which a nitrile group is substituted with a hydrocarbon main chain (US Pat. No. 3,476,832), a method of mixing aliphatic polyether (JP-A 50-33095), α- A method of mixing an olefin polymer and a copolymer of an ethylene / vinyl monomer (Japanese Patent Laid-Open No. 49-40346), a polyolefin-based, polystyrene-based, polyester-based, or polyamide-based thermoplastic elastomer However and a method of mixing (Japanese Unexamined places No. 60-104116), could significantly improve the impact strength due to insufficient compatibility with POM.

In addition, there is a method of mixing thermoplastic polyurethane as an elastomer for imparting higher toughness (Canada Patent No. 84-2325). Method to improve the toughness by controlling the dispersion of polyurethane (Japanese Patent Laid-Open No. 59-155453), and to prepare and mix a special elastomeric polyurethane to improve compatibility with POM (Japanese Patent Laid-Open No. 59-145243) And so on. However, when polyurethane is mixed with POM, the higher the amount of polyurethane, the impact strength is improved, but due to the deterioration of rigidity such as formability, tensile strength, flexural strength, etc., it is difficult to use it as a real product.

As a method for improving the wear characteristics of the POM resin, a method of adding silicone oil (Japanese Patent Laid-Open No. 60-41449, Japanese Patent Application Laid-Open No. 1-204959) is disclosed, but there is a problem that mold contamination occurs due to silicone oil. .

In addition, techniques for improving the POM wear resistance characteristics include a method of adding solid lubricants such as molybdenum disulfide and graphite, a method of adding powdered and fibrous polytetraethylene resins, or petroleum lubricants, aliphatic alcohols or esters thereof. Methods of adding lubricants are known.

Such methods can sufficiently improve the wear resistance of friction, but when sliding at a low speed and low load, the friction resistance is remarkably degraded.

In addition, when the polytetrafluoroethylene resin is added, there is a problem in that the mechanical properties are excellent although the friction resistance is excellent. In addition, in the case of using lubricants such as petroleum lubricants, aliphatic alcohols or esters thereof, the compatibility with the POM resin is insufficient and the mold surface is moved to the mold surface during molding, resulting in mold glossiness and dimensional instability. there is a problem.

The present inventors have studied to solve the above problems, and as a result, the polyether component contains poly (ethylene oxide) glycol of a specific molecular weight and uses a neoalkoxy titanate or neoalkoxy zirconate compound to It is an object of the present invention to provide a polyoxyethylene resin composition capable of improving not only mechanical properties, particularly rigidity, but also wear resistance by improving adhesion properties between copolymers.

In order to achieve the above object, the polyoxymethylene resin composition of the present invention comprises 100 parts by weight of polyoxymethylene resin, 10 to 60 parts by weight of polyether-ester block copolymer, neoalkoxy titanate or neoalkoxy zirconate compound 0.05 to It is characterized by consisting of 5 parts by weight.

The present invention will be described in more detail as follows.

The present invention relates to a POM resin composition having improved impact strength and frictional wear resistance while maintaining mechanical strength.

In the present invention, in order to improve the impact resistance of the POM resin composition, a dicarboxylic acid component mainly composed of terephthalic acid, a glycol component mainly composed of 1,4-butanediol together with the POM resin, and a poly (ethylene oxide) glycol having a number average molecular weight of 800 to 20,000. 10 to 60 parts by weight of a polyether-ester block copolymer derived from and having a poly (ethylene oxide) dicarboxylate unit content of 40 to 85 parts by weight.

In addition, neoalkoxy titanate or neoalkoxy zirconate compound is added to the POM resin to improve the wear resistance friction characteristics and to maintain the mechanical strength by increasing the interfacial adhesion between the polyethylene-ester copolymer and the POM resin. .

The POM resin composition thus obtained has mechanical properties such that the notched Izod impact strength maintains a high impact strength of 30 kg · cm / cm or more and a tensile strength of 550 kg / cm 2 or more, while the frictional coefficient is 0.2 or less and the wear resistance is 1 or less. Material composition showing wear characteristics.

First, in order to improve impact resistance, a dicarboxylic acid component containing terephthalic acid as a main component, a glycol component containing 1,4-butanediol as a main component, and a poly (ethylene oxide) glycol having a number average molecular weight of 800 to 20,000 based on 100 parts by weight of POM resin 10 to 60 parts by weight of a polyether-ester block copolymer derived from and having a poly (ethylene oxide) dicarboxylate unit content of 40 to 85 parts by weight.

POM resin used in the present invention means a POM copolymer containing oxymethylene homopolymer and 15 parts by weight or less of oxymethylene units having 85 parts by weight or more of oxymethylene units and 2 to 8 adjacent carbon atoms in the main chain. The method for producing the oxymethylene homopolymer and the oxymethylene copolymer is not particularly limited and can be produced by a known production method.

For example, as a typical method for preparing an oxymethylene homopolymer, substantially anhydrous formaldehyde is introduced into an organic solvent containing a basic polymerization catalyst such as an organic amine, polymerized, and then the polymer formed is, for example, acetic anhydride. Mention may be made of stabilization by acetylation.

As a typical method for preparing the oxymethylene copolymer, substantially anhydrous trioxane and copolymerization component (e.g. ethylene oxide or 1,3-dioxolene) are directly polymerized or in a solvent (e.g. cyclohexane or benzene). Mention may be made of polymerization using a Lewis acid catalyst (eg boron trifluoride-diethyl etherate), decomposition and then removal of unstable ends using a basic compound.

The polyether-ester block copolymer used in the present invention is a segmented block copolymer comprising a hard segment mainly composed of butylene terephthalate units and a soft segment mainly composed of poly (ethylene oxide) terephthalate units. .

The dicarboxylic acid component constituting the hard segment consists solely of terephthalic acid, but consists of at least 70 mol% of terephthalic acid alone, or at least 70 mol% of terephthalic acid and up to 30 mol% of aromatic dicarboxylic acid (e.g. isophthalic acid, phthalic acid, naphthalene -2,6-dicarboxylic acid, diphenyl-4,4'-dicarboxylic acid or 3-sulfonisophthalic acid, alicyclic dicarboxylic acids (e.g. oxalic acid, succinic acid, adipic acid, azelic acid, sebacic acid, dodecanoic acid or dimers) Body weight). Among these copolymerization components, preferably used are isophthalic acid, adipic acid, sebacic acid and dodecanoic acid.

The diol component constituting the hard segment mainly consists of 1,4-butanediol. That is, the diol component consists of 1,4-butanediol alone, or at least 50 mol% of 1,4-butanediol and up to 50 mol% of copolymerized components (e.g., ethylene glycol, diethylene glycol, propylene glycol, 1,6-hexane Diol, 1,10-decanediol, 1,4-dihydroxymethyl cyclohexane, bis (4-hydroxyethoxyphenyl) methane or neopentyl glycol).

The dicarboxylic acid component constituting the soft segment consists mainly of terephthalic acid. The dicarboxylic acid component of the soft segment, like the dicarboxylic acid component of the hard segment, consists of terephthalic acid alone, or contains 70 mol% or more of terephthalic acid and 30 mol% or less of dicarboxylic acid as a copolymerization component. As the copolymerization component, mention may be made of dicarboxylic acids as exemplified above for the hard segments.

As poly (ethylene oxide) glycol which comprises the poly (ethylene oxide) terephthalate unit which is a soft segment, the poly (ethylene oxide) glycol whose number average molecular weight is 800-20,000 is used. Poly (ethylene oxide) glycols having a number average molecular weight of 5,000 to 15,000 are preferable, and poly (ethylene oxide) glycols having a number average molecular weight of 8,000 to 10,000 are particularly preferable in view of compatibility with POM resin. In this case, when the number average molecular weight is less than 500, the impact resistance effect is too small, and when the number average molecular weight is greater than 20,000, compatibility with the butyl terephthalate unit of the hard segment may be poor, thereby preparing a homogeneous polyether-ester block copolymer. none.

In the polyether-ester block copolymer used in the present invention, between a hard segment mainly composed of butylene terephthalate units and a soft segment mainly composed of poly (ethylene oxide) terephthalate units (poly (ethylene oxide) carboxylate units) The composition ratio is 40 to 85% by weight, preferably 70 to 85% by weight, of the content of the poly (ethylene oxide) carboxylate unit. If the content of poly (ethylene oxide) carboxylate units is greater than 85% by weight, the polyether-ester block copolymer is difficult to polymerize and the mechanical strength of the composition is lowered.

The method for producing the polyether-ester block copolymer is not particularly limited and can be produced by known conventional methods. In one example, the polyether-ester block copolymer is obtained by placing terephthalic acid (or dimethyl terephthalate), 1,4-butanediol, and poly (ethylene oxide) glycol in a reaction vessel equipped with a rectification column and reacting the reaction under atmospheric pressure or elevated pressure. (Or transesterification), followed by polymerization under atmospheric or reduced pressure. The polyether-ester block copolymers can also be prepared by adding terephthalic acid (or dimethyl terephthalate) and 1,4-butanediol, poly (ethylene oxide) glycol to the oligomer followed by polymerization under atmospheric or reduced pressure.

In the present invention, the amount of the polyether-ester block copolymer added is 10 to 60 parts by weight, preferably 15 to 40 parts by weight based on 100 parts by weight of the POM resin. When the amount of the polyether-ester block copolymer added is less than 10 parts by weight, the impact resistance and permanent antistatic property are insufficient, and when the amount of the polyether-ester block copolymer added is more than 60 parts by weight, the mechanical strength is low. It is greatly reduced.

Meanwhile, in the POM resin composition of the present invention, the neoalkoxy titanate or neoalkoxy zirconate compound is 0.005 to 5 parts by weight based on 100 parts by weight of the polyoxymethylene resin so as to maintain the mechanical strength by increasing the interfacial adhesion with the POM resin. Add.

The neoalkoxy titanate or neoalkoxy zirconate compound used in the present invention is represented by the following formula (1).

Wherein R, R ₁ and R ₂ are the same as or different from each other and are primary alkyl, alkenyl, alkynyl, aryl or alkaryl groups or halogen or ether substituted derivatives having 1 to 20 carbon atoms, in addition R ₂ is Is an oxy derivative or an ether substituted oxy derivative, M is titanium or zirconium, A, B and C are ethoxy (ArO-), thioaoxy (ArS-), and satisfy the relationship of x + y + z = 3. do.

If the amount of such compound is large, it may not be preferable because it may give plasticity to the resin phase, and if it is small, there is no effect.

In addition, unless otherwise contrary to the object of the present invention, known hindered phenolic, phosphite, thioether or amine antioxidants, benzophenone or hindered amine weathering agents, formaldehyde scavengers (e.g. Melamine, dicyandiamide, polyamide or polyvinyl alcohol copolymer), release agents (e.g. fluorine-containing polymers, silicone oils, metal salts of stearyl acid, metal salts of montanic acid, montanic acid ester waxes or polyethylene waxes), colorants (dyes Or pigments), sunscreens (e.g. titanium oxide or carbon black), reinforcements (e.g. glass fiber, carbon fiber or potassium titanate fiber), fillers (e.g. silica, clay, calcium carbonate, calcium sulfate or glass beads), nucleus Forming agents (eg talc, clay), plasticizers, adhesion aids, and pressure sensitive adhesives may be added to the POM composition for use.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by the Examples.

In the present invention, the physical properties were measured according to the following method.

(1) Relative viscosity (ηr) is a value measured at 25 ° C by making a solution having a polymer concentration of 0.5% using o-chlorophenol as a solvent.

(2) Mechanical properties: Using an injection molding machine having an injection capacity of 60 tons, ASTM dumbbell test specimens and Izod impact test specimens are molded at a cylinder temperature of 190 ° C, a mold temperature of 80 ° C, and a molding cycle of 40 seconds. The tensile strength is measured according to the method of ASTM D-638 using the above-mentioned tensile test piece, and the impact strength is measured according to the method of ASTM D-256 using the Izod impact test piece.

(3) Wear and friction characteristics: Sliding in a trust abrasion tester (No. 392, manufactured by Toyo Seki Co., Ltd.) by a metal (S45C) as the opposite material at a pressure of 20 kg / cm 2, a linear speed of 10 cm / sec, and a contact area of 2 cm 2. The coefficient of kinetic friction and wear was measured for 60 minutes.

Preparation Example 1

Reaction vessel with spiral ribbon stir blade: 1,000g dimethyl terephthalate, 1,085g poly (ethylene oxide) glycol with number average molecular weight 8,000, 823g 1,4-butanediol and 0.005% (based on polymer) Titanium tetrabutoxide catalyst was charged, and the mixture was heated at 190 to 225 ° C for 3 hours to effect transesterification. The temperature was then raised to 245 ° C. and the pressure in the system was reduced to 1 mm Hg over 50 minutes. The polymerization was carried out under these conditions for 2.5 hours. The obtained polymer was extruded into water in the form of strands and cut to obtain pellets. This polymer is referred to as polymer A-1.

Polymerization was carried out in the same manner as above to prepare Polymer A-2 having the composition shown in Table 1 below. The relative viscosity of each polymer obtained is shown in Table 1 below.

Butylene terephthalate (parts by weight) Poly (ethylene oxide) terephthalate (part by weight) Relative viscosity (ηr) A-1 50 50 2.10 A-2 20 80 2.92

Reference Example 2

The reaction vessel was filled with 1,000 g of dimethyl terephthalate, 1,499 g of poly (ethylene oxide) glycol having a number average molecular weight of 3,000, and 465.6 g of 1,4-butanediol, and polymerization was carried out in the same manner as described in Preparation Example 1. Was performed. The obtained polymer is called polymer B-1. Polymer B-2 was prepared in the same manner using poly (ethylene oxide) glycol having a molecular weight of 15,000. The hard segment / soft segment composition ratio in each of polymers B-1 to B-2 is 20/80 parts by weight. The relative viscosity of each polymer obtained is shown in Table 2 below.

Soft Segment Components-Molecular Weight Relative viscosity (ηr) B-1 Poly (ethylene oxide) glycol-3,000 2.62 B-2 Poly (ethylene oxide) glycol-15,000 3.94

Examples 1-8 and Comparative Examples 1-4

The POM resin was dried in vacuo at 80 ° C. for 4 hours, the temperature of the cylinder was set to 190 ° C. using a twin-screw thermomelting kneader, and the POM resin and neoalkoxy titanate or neoalkoxy zirconate compound were prepared. The polyether-ester copolymers (A-1, A-2, B-1, and B-2) were introduced into the composition according to Table 3 while mixing and feeding into the primary inlet. It was sufficiently melt mixed at the temperature. This was discharged into a spaghetti through a die, cooled, cut into pellets and cut into chips. The resin composition thus obtained was well dried and then injection molded and measured for physical properties at 190 ° C., and the results are shown in Table 4 below.

POM resin Polyether-ester copolymer (parts by weight) Neoalkoxy compound (parts by weight) Example One 100 B-2 (50) C (1.0) 2 100 B-2 (40) C (0.5) 3 100 A-2 (35) D (0.3) 4 100 B-1 (30) C (0.2) 5 100 A-2 (25) D (0.5) 6 100 B-1 (20) D (0.3) 7 100 A-1 (20) C (0.05) 8 100 A-1 (20) D (0.7) Comparative example One 100 A-1 (25) D (0.01) 2 100 B-2 (30) D (10) 3 100 A-2 (70) D (0.5) 4 100 B-1 (5) C (1.0)

Izod impact strength (kgcm / cm) Tensile Strength (kg / ㎠) Dynamic Friction Coefficient (μ) Abrasion Amount ㎣ / (N-m) Example One 48 594 0.11 0.2 2 45 578 0.12 0.3 3 44 570 0.13 0.3 4 38 568 0.14 0.5 5 35 565 0.15 0.5 6 31 554 0.15 0.8 7 32 572 0.17 0.8 8 31 575 0.18 0.6 Comparative example One 22 550 0.29 2.1 2 38 480 0.25 2.5 3 55 398 0.20 2.4 4 12 560 0.17 1.4 C: neoalkoxy titanate compound- (CH ₂ = CH-CH ₂ OCH ₂ ) ₂ (C ₂ H ₅ ) CCH ₂ OTi [OC (O) neo-C ₉ H ₁₉ ] ₃ D: neoalkoxyzirconate compound -(CH ₂ = CH-CH ₂ OCH ₂ ) ₂ (C ₂ H ₅ ) CCH ₂ OZr [OC (O) neo-C ₉ H ₁₉ ] ₃

POM resin composition according to the present invention from the results of Table 3 has a tensile strength of 500kg / ㎠ or more, impact strength of 30kgcm / cm or more, dynamic friction coefficient of at least 0.2 level and the amount of non-wear wear 1 level power, such as gears It can be seen that the friction-wear characteristics were improved enough to be applied as a transfer material.

As described in detail above, according to the present invention, polyether-ester copolymer is added to the polyoxymethylene resin to improve impact resistance, and a neoalkoxy titanate or neoalkoxy zirconate compound is added to the polyether- The resin composition, which maintains the mechanical strength by increasing the interfacial adhesion between the ester copolymer and the polyoxymethylene resin, has mechanical properties such that the impact strength is 30 kg · cm / cm or more and the tensile strength is also 550 kg / cm 2 or more. The frictional friction coefficient is 0.2 or less and the frictional wear resistance is 1 or less, so that it can be applied to various gears and the like without any problem.

Claims (4)

A polyoxymethylene resin composition comprising 100 parts by weight of a polyoxymethylene resin, 10 to 60 parts by weight of a polyether-ester block copolymer, and 0.05 to 5 parts by weight of a neoalkoxy titanate or neoalkoxy zirconate compound. The polyoxymethylene resin composition according to claim 1, wherein the neoalkoxy titanate or neoalkoxy zirconate compound is represented by the following formula (1). Formula 1 Wherein M is titanium or zirconium, R, R ₁ and R ₂ are the same as or different from each other, and are alkyl, alkenyl, alkynyl, aryl or alkaryl groups or halogen or ether substituted derivatives having 1 to 20 carbon atoms, in addition R ₂ is an oxy derivative of the above groups or Ether substituted oxy derivatives, A, B and C are ethoxy (ArO-), thioatoxy (ArS-), satisfies x + y + z = 3 The neoalkoxy titanate or neoalkoxy zirconate compound according to claim 1 or 2, wherein (CH ₂ = CH-CH ₂ OCH ₂ ) ₂ (C ₂ H ₅ ) CCH ₂ OM [OC (O) neo- C ₉ H ₁₉ ] ₃ (wherein M is titanium or zirconium) polyoxymethylene resin composition. The polyoxymethylene resin composition according to claim 1, wherein the polyoxymethylene resin composition has an Izod impact strength of 30 kg · cm / cm or more, a dynamic friction coefficient of 0.2 or less, and a specific wear amount of 1 kPa / (N-m) or less.