KR101504676B1 - Glass fiber-reinforced polyoxymethylene-polylatic acid composition - Google Patents

Abstract

The present invention relates to a reinforced polyoxymethylene-polylactic acid composition, which comprises a resin composition comprising polyoxymethylene, polylactic acid, styrene-acrylate copolymer and glass fiber. The resin composition according to the present invention is expected to be applicable to various fields requiring excellent heat resistance due to excellent gloss and appearance, low occurrence of warpage, high heat stability and high heat distortion temperature.

Description

BACKGROUND ART [0002] Glass fiber-reinforced polyoxymethylene-polylic acid composition

The present invention relates to an enhanced polyoxymethylene-polylactic acid composition.

Until recently, the research direction of polymer materials was mainly led to the development of strong specialty polymer materials and the safety of polymer materials. However, the environmental pollution problem caused by the waste polymer is becoming a social problem in the world. Therefore, the necessity of environment - friendly polymer material is required.

Environmentally Compatible Polymers are classified into photodegradable and biodegradable polymers. Polymer materials with complete biodegradability in the environment have a family of functional groups capable of decomposing by the microbes in the main chain structure.

Among them, aliphatic polyester polymers have been studied extensively because of their excellent processability and easy control of their decomposition characteristics. Particularly in the case of polylactic acid (PLA), a market of 150,000 tons is formed worldwide, Containers, electronic cases and other general plastics have been used. However, the product is easily broken due to lack of moldability, mechanical strength and heat resistance, and resistance to temperature is low, so that when the external temperature rises above 60 ° C, there is a problem that the shape of the molded product is deformed.

The polyoxymethylene resin (POM or polyacetal) is excellent in moldability and processability, and is advantageous as a blend resin with a polylactic acid resin because it can be processed at a low processing temperature of polylactic acid resin. The polyoxymethylene resin is excellent in hydrolysis resistance and can be an important resin as a composite material with polylactic acid since the disadvantage of the polylactic acid resin can complement the hydrolytic property.

The polyoxymethylene resin is also a polymer having physical properties such as excellent friction characteristics, hardness, suitable toughness and rapid crystallization ability. Only some commercially available rubber-type materials are sufficiently compatible so that they are dispersed in the melt with sufficiently small particles and then fully adhered to the solid state to allow for stress transmission across the rubber-matrix interface, thereby improving its impact resistance so that the POM is highly impact- Finally, it is one of the most important engineering polymers.

Korean Patent Laid-Open No. 10-2006-0010707 (Patent Document 1) discloses a blend of a polyoxymethylene resin and a polylactic acid which may contain an impact modifier.

However, the necessity of a composition having an excellent appearance (surface gloss, warpage, etc.) and improved mechanical rigidity is higher than that of a molded product of a conventional composition, and the thermal decomposition and thermal deformation of the composition during processing (injection molding and extrusion molding) There is an increasing need for a composition that is more excellent than the above.

Korean Patent Publication No. 10-2006-0010707

It is an object of the present invention to provide a resin composition excellent in appearance (surface gloss, warpage, etc.) and mechanical rigidity, and it is an object of the present invention to provide a resin composition It is an object of the present invention to provide a resin composition having better heat stability and heat distortion temperature.

It is also an object of the present invention to provide an injection-molded article and an extruded article using such a resin composition.

According to an aspect of the present invention,

Polylactic acid, styrene-acrylate copolymer, and glass fiber.

Specifically, it is possible to provide a resin composition comprising 10 to 90% by weight of polyoxymethylene, 1 to 50% by weight of polylactic acid, 0.05 to 5% by weight of styrene-acrylate copolymer and 5 to 50% have.

At this time, the resin composition may further include one or more of a thermal decomposition stabilizer, an antioxidant, and a compatibilizer.

The thermal decomposition stabilizer may be ethylene vinyl alcohol (EVOH), a hydrazine additive, or a mixture thereof.

The antioxidant may be a hindered phenol-based oxidizing agent.

The compatibilizer may be a bismaleimide triazine monomer, a polycarbonate resin, or a mixture thereof.

The extrudates and extrudates comprising the resin composition of the present invention are included in the scope of the present invention.

The resin composition according to the present invention is expected to be applicable to various fields requiring excellent heat resistance due to excellent gloss and appearance, low occurrence of warpage, high heat stability and high heat distortion temperature.

Specifically, it is possible to provide a resin composition which is superior in appearance (surface gloss, warpage, etc.) and mechanical rigidity to a composition comprising only polylactic acid and glass fiber, and can provide a resin composition excellent in thermal stability and heat resistance during processing (injection molding and extrusion molding) It is expected that injection molding and extrusion molding can be easily manufactured and the properties thereof are also excellent so that the use thereof as eco-friendly injection molding will be diversified.

Fig. 1 compares the appearance of Example 1 and Comparative Example 1,
Fig. 2 compares the appearance gloss of Example 1 and Comparative Example 1,
Fig. 3 compares the external warpage of Example 1, Comparative Example 1 and Comparative Example 6. Fig.

The present invention relates to a resin composition comprising polyoxymethylene, polylactic acid, styrene-acrylate copolymer and glass fiber.

The present invention provides a polyoxymethylene-polylactic acid copolymer comprising a styrene-acrylate copolymer, which surprisingly shows excellent heat resistance, heat distortion temperature, and strength of glass fiber, thereby completing the present invention Respectively.

The polyoxymethylene (POM or polyacetal) used in the present invention may be one or more homopolymers, copolymers, or mixtures thereof. The homopolymer is prepared by the polymerization of formaldehyde equivalents such as formaldehyde or cyclic oligomers of formaldehyde. The copolymers may contain one or more comonomers commonly used in the preparation of polyoxymethylene compositions. Commonly used comonomers include acetals and cyclic ethers which result in the incorporation of ether units having 2 to 12 consecutive carbon atoms in the polymer chain. When selecting the copolymer, the amount of comonomer will be up to 20 wt%, preferably up to 15 wt%, and most preferably up to about 2 wt%. Preferred comonomers are 1,3-dioxolane, ethylene oxide, and butylene oxide and 1,3-dioxolane is more preferred and preferred polyoxymethylene copolymers are copolymers having a comonomer content of about 2 wt% to be.

More specifically, it relates to: 1) a homopolymer in which a terminal hydroxy group is end-capped by a chemical reaction to form an ester group or an ether group, or 2) a terminal group which is not completely terminal-capped but has some free hydroxy- Terminated copolymers are also preferred as homopolymers and copolymers. For homopolymers, the preferred end groups are acetate and methoxy, and in the case of copolymers, the preferred end groups are hydroxy and methoxy.

The polyoxymethylene used in the composition of the present invention may be branched or linear and will generally have a number average molecular weight in the range of 10,000 to 150,000, preferably 20,000 to 90,000, and more preferably 25,000 to 70,000. The molecular weight can be conveniently measured by gel permeation chromatography in m-cresol using a DuPont PSM bimodal column kit with a nominal pore size of 60-1000 A at 160 < 0 > C. Molecular weights can also be determined by determining the melt flow using ASTM D1238 or ISO 1133. The melt flow will range from 0.1 to 100 g / min, preferably from 0.5 to 60 g / min, or more preferably from 0.8 to 40 g / min for injection molding purposes. Other melt viscosity ranges may be desirable for other structures and processes such as films, fibers, and blow molding. Specific examples of the manufacturer include 4060 grades of Natureworks LLC and 101L of Hisun Co. (non-nucleating agent).

The polyoxymethylene thus produced may contain 10 to 90% by weight, specifically 15 to 50% by weight, based on the resin composition. If it is less than 10% by weight, it may interfere with injection molding due to physical limitations such as brittleness and slow crystallization, and there may be a problem of lowering thermal stability, lowering heat resistance and deteriorating high temperature properties, The mechanical properties and the appearance improving effect may be insignificant.

Next, the polylactic acid (PLA) used in the present invention is a polylactic acid (PLA) having a number average molecular weight of 3,000 to 1,000,000 or preferably 10,000 to 700,000 or more preferably 20,000 to 600,000, and 50 moles of a repeating unit derived from lactic acid or a derivative thereof and a mixture thereof % Or more of a polylactic acid copolymer and a polylactic acid homopolymer. Preferably, the polylactic acid used in the present invention may contain at least 70 mol% of polylactic acid repeating units derived from lactic acid or a derivative thereof. The polylactic acid homopolymer and polylactic acid copolymer used in the present invention may be derived from d-lactic acid, 1-lactic acid, or a mixture thereof. Mixtures of two or more polylactic acid polymers can be used. Polylactic acid is typically prepared by catalyzed ring opening polymerization of a dimeric cyclic ester of lactic acid, referred to as "lactide ". As a result, polylactic acid is also referred to as "polylactide ". Polylactic acid can also be produced by organisms such as bacteria or isolated from plant material including corn, sweet potatoes and the like. The polylactic acid produced by the organism may have a higher molecular weight than that produced by synthesis.

Copolymers of lactic acid (polylactic acid) are typically prepared by catalyzed copolymerization of one or more cyclic esters and / or dimeric cyclic esters with lactides or other lactic acid derivatives. Typical comonomers include glycolide (1,4-dioxane-2,5-dione), dimeric cyclic ester of glycolic acid; α, α-dimethyl-β-propiolactone, cyclic esters of 2,2-dimethyl-3-hydroxypropanoic acid; ? -butyrolactone, cyclic esters of 3-hydroxybutyric acid,? -valerolactone, cyclic esters of 5-hydroxypentanoic acid; epsilon -caprolactone, cyclic esters of 6-hydroxyhexanoic acid, and methyl substituted derivatives thereof such as 2-methyl-6-hydroxyhexanoic acid, 3-methyl-6-hydroxyhexanoic acid, Hexanoic acid, 3,3,5-trimethyl-6-hydroxyhexanoic acid, etc., cyclic esters of 12-hydroxydododecanoic acid, and 2-p-dioxanone, 2- - < / RTI > hydroxyethyl) -glycolic acid. Aliphatic and aromatic diacids and diol monomers such as succinic acid, adipic acid, and tetraphthalic acid and ethylene glycol, 1,3-propanediol, and 1,4-butanediol may also be used. Copolymers can also be prepared by living organisms or isolated from plant material as described above. The polylactic acid thus produced may contain 1 to 50% by weight, specifically 15 to 30% by weight, based on the resin composition. If it is less than 1% by weight, the effect of improving the mechanical properties and appearance of the present invention may be insignificant. If it exceeds 50% by weight, the thermal stability of the POM composition may deteriorate and the heat resistance, It may interfere with injection molding due to physical limitations.

In the present invention, the styrene-acrylate copolymer may be used alone as styrene-acrylate, and styrene-acrylate block copolymer or random copolymer may be used. The inventors of the present invention discovered that when the styrene-acrylate copolymer is applied to the resin composition of the present invention, the mechanical rigidity and appearance properties of the molded article are remarkably enhanced, thereby completing the present invention. In addition, the styrene-acrylate copolymer serves to further increase the heat distortion temperature of the composition of the present invention.

In addition, the styrene-acrylate copolymer may serve as a hydrolysis stabilizer for PLA, and may be in the form of a random copolymer or a block copolymer. By applying the hydrolysis stabilizer, the mechanical properties of the POM glass fiber PLA composition may be improved, and the thermal and optical properties may be improved. When incorporated into the composition according to the present invention, the content is not particularly limited, but may be from 0.05 to 5% by weight, more specifically from 0.1 to 1% by weight, of the total resin composition. If the amount is less than 0.05% by weight, the above effects can not be attained. If the amount is 5% by weight or more, the moldability may be deteriorated.

In the present invention, the glass fiber (glass fiber) is not particularly limited, but the length of the glass fiber is 0.3 mm to 2 cm, more specifically, 3 mm to 1 cm, and the coating agent is urethane-based. The content of the glass fiber is not particularly limited, but may be 5 to 50% by weight, more preferably 10 to 30% by weight, of the total resin composition. If the amount is less than 5% by weight, there may be problems such as a decrease in mechanical strength and a decrease in heat distortion temperature. If the amount is more than 50% by weight, there may be a problem in the thermal stability of the POM composition. In the case of the composition comprising the conventional POM and the glass fiber, the maximum content of the glass fiber is 30 wt%, which has limitations in increasing the mechanical strength. The present invention allows a higher than 50 wt% content to be contained, and thus can have much more favorable physical properties than existing injection molds in terms of gloss and strength.

The composition according to an embodiment of the present invention may further comprise at least one optional grafting catalyst. The grafting catalyst is described in U.S. Patent No. 4,912,167. The grafting catalyst is a cationic catalyst, for example ^{Al 3+, Cd 2+, Co 2+} , Cu 2+, Fe 2+, In 3+, Mn 2+, Nd 3+, Sb 3+, Sn 2+, and Zn ^{2 +} . Suitable grafting catalysts include, but are not limited to, hydrocarbons mono-, di-, or polycarboxylic acids such as acetic acid and stearic acid. Inorganic salts such as carbonates may also be used. Examples of preferred grafting catalysts include, but are not limited to, tin octanoate, zinc stearate, zinc carbonate, and zinc diacetate (hydrates or anhydrides). If used, the grafting catalyst will preferably be from about 0.01 to about 3 parts by weight per 100 parts by weight of the total resin composition.

In addition, the composition according to an embodiment of the present invention may further include one or more of a heat stabilizer, an antioxidant, and a compatibilizer. The heat stabilizer is meant to help stabilize the composition of the present invention at elevated temperatures, such as molding temperatures. Preferred are ethylene vinyl alcohol (EVOH) or hydrazine based additives, but are not limited thereto. When contained in the polyacetal composition of the present invention, the amount of the at least one heat stabilizer is preferably 0.05 to 1.50 wt%, more preferably 0.20 to 1.00 wt%.

Examples of the antioxidant include a hindered phenol-based oxidizing agent, and specifically, N, N'-hexane-1,6-diylbis (3- (3,5-di- tert- butyl-4-hydroxyphenylpropion amide) But is not necessarily limited thereto. When included in the composition according to the present invention, the content thereof may be 0.05 to 1% by weight.

The compatibilizing agent specifically means a compatibilizing agent of glass fiber and POM in the composition according to the present invention, and a bismaleimide triazine monomer or polycarbonate resin may be applied. By the application of the compatibilizer, the bonding of the glass fiber and the POM becomes strong, and the effect of increasing the physical properties may be obtained. When included in the composition according to the present invention, the content thereof may be 0.05 to 5% by weight.

In embodiments of the present invention, it is preferred that the resin composition is prepared by melt blending polyoxymethylene, polylactic acid, styrene-acrylate copolymer and glass fiber until uniformly dispersed when viewed with naked eye, The layer is not peeled off. Other materials (other additives) can be uniformly dispersed in the resin composition.

The blend can be obtained by combining the component materials using any melt-mixing method known in the art. For example: 1) the resin composition can be obtained by uniformly mixing the component materials using a melt-mixer such as a single or twin-screw extruder, a blender, a kneader, a Banbury mixer, a roll mixer or the like; Or 2) a portion of the constituent material may be mixed in a twin-screw mixer and the remaining constituent material added subsequently through the inlet and further melted-mixed until homogeneous. For example, it is possible to use a method in which polyoxymethylene, polylactic acid and styrene-acrylate copolymer are melted in a twin-screw mixer and glass fibers are subsequently added and mixed.

The composition according to an embodiment of the present invention may be molded into an article using any suitable melt-processing technique. But are not limited to, melt blow molding methods commonly known in the art such as injection molding, extrusion molding, blow molding and injection blow molding.

The composition according to an embodiment of the present invention can be formed into a film and a sheet by extrusion to produce both a cast and a blown film. The sheet may be further thermoformed from the melt or into the article and structure to be oriented at a later stage of processing of the composition. The sheet is about 10 mil (0.010 inches) thick or more. The film has a thickness of 0 to 10 mils (0.010 inches). The film may also be a co-extruded film or part of an extruded layer-formed multilayer structure. The compositions of the present invention may also be used to form fibers and filaments that can be oriented from the melt or at a subsequent stage of processing of the composition. Examples of articles that may be formed from the compositions of the present invention include, but are not limited to, knobs, buttons, disposable food containers, thermoformed sheets, and the like. The present invention is also applicable to the automobile field.

Hereinafter, preferred embodiments will be described in order to facilitate understanding of the present invention. However, the following examples are illustrative of the present invention, and the scope of the present invention is not limited to the following examples.

≪ Example 1 >

43% by weight of polyoxymethylene (POM, F40-03 from KEPITAL), 30% by weight of polylactic acid (PLA, 4060D from Natureworks LLC), 0.1% by weight of styrene-acrylate copolymer ADR, Basf Joncryl ADR4368), 1% by weight of a hindered phenolic antioxidant (N, N'-hexane-1,6-diylbis 0.5 weight% and hydrazine 0.5 weight% were blended in a main hopper of a Twin Screw Compounding machine (manufactured by JSW, Japan). The screw speed was 180 rpm and the temperature condition was 210 캜. The temperature in the mixer melted and kneaded for 1 hour was lowered to 180 캜, and 25% by weight of glass fiber was put into a side feeder to melt-mix the composition for 30 minutes. The generated vapor was prevented from being discharged to the vacuum vent portion so as to prevent the backflow to the supply portion of the resin composition. The resin composition thus prepared was injected through an injection molding machine (Fanac electric injection machine, injection speed: 20 mm / s, injection pressure: 700 kgf, metering: 50 mm, cooling time: 10 sec, mold temperature: 80 degrees).

The thus-injected specimens were evaluated by a standard test method. The evaluation method is as follows. The physical properties are shown in Table 2 below.

1) Tensile strength and tensile elongation = ISO 527

2) Flexural strength and flexural modulus = ISO178

3) charpy impact strength = ISO179

4) Specific gravity = ISO1183-1

5) Shrinkage = ISO294

6) Heat distortion temperature = measured at 1.8 MPa using 4 mm (3%) thickness test bars according to ISO 75 / Ae

7) ** VDA275 (thermal stability evaluation)

8) Other appearance characteristics (warp, gloss, etc.) are visually confirmed after injection molding

[Table 1] Composition of Examples 1 to 7 and Comparative Examples 1 to 3

[Table 2] Physical properties of Examples 1 to 7 and Comparative Examples 1 to 3

** VDA275 Rating Method

A method for evaluating the thermal stability of POM by measuring formaldehyde emission from POM pyrolysis is to fill a 1 liter polyethylene bottle with a certain amount of distilled water, Close to maintain confidentiality. The oven is kept at a constant temperature to dissolve the released formaldehyde component in distilled water. After cooling the polyethylene bottle to room temperature, the total amount of formaldehyde dissolved in the distilled water is pretreated by the * acetylacetone method, and the result is measured with an ultraviolet spectrometer.

(* Acetylacetone method: Formaldehyde reacts with ammonium ion and acetylacetone to form 2,5-diacety-1,4-dihydrolutidin (DDL), which is the substance exhibiting the maximum absorption wavelength at UV 412 nm.)

≪ Example 2 >

63.5% by weight of polyoxymethylene (POM, F40-03 from KEPITAL), 10% by weight of polylactic acid (PLA, 4060D from Natureworks LLC) in styrene-acrylate copolymer (ADR , 1% by weight of Basf Joncryl ADR4368) and 0.5% by weight of a hindered phenolic antioxidant (N, N'-hexane-1,6-diylbis Weight% was added to the main hopper of a twin screw mixer (Twin Screw Compounding machine, JSW, Japan) for blending. The screw speed was 180 rpm and the temperature condition was 210 캜. The temperature in the mixer melted and kneaded for 1 hour was lowered to 180 캜, and 25% by weight of glass fiber was put into a side feeder to melt-mix the composition for 30 minutes. The generated vapor was prevented from being discharged to the vacuum vent portion so as to prevent the backflow to the supply portion of the resin composition. The resin composition thus prepared was injected through an injection molding machine (Fanac electric injection machine, injection speed: 20 mm / s, injection pressure: 700 kgf, metering: 50 mm, cooling time: 10 sec, mold temperature: 80 degrees).

The thus-injected specimens were evaluated by a standard test method. The evaluation method is the same as in Example 1, and the physical properties are shown in Table 2 below.

≪ Examples 3 to 7 >

The results are shown in Table 2 below. ≪ tb > < TABLE >

≪ Comparative Examples 1 to 4 >

The results are shown in Table 2 below. ≪ tb > < TABLE >

The appearance of the specimen prepared according to Example 1 of the present invention and the specimen prepared according to Comparative Example 1 were observed and shown in FIG. It was confirmed that the composition excluding the polylactic acid exhibited a smooth appearance and an outward appearance.

The appearance of the specimen prepared according to Example 1 of the present invention and the specimen prepared according to Comparative Example 1 were observed and shown in Fig. It was confirmed that the composition excluding the polylactic acid was significantly lower in gloss.

Finally, the specimens prepared according to Example 1 of the present invention and the specimens prepared according to Comparative Example 1 were observed to show the external warpage. In addition, in the composition of Comparative Example 1, a specimen of Comparative Example 4 using PA-6 (Polyamide-6) instead of polyoxymethylene was prepared. 3 is a photograph immediately after molding, and "after" is a photograph in which a warping (distortion) of a molded article occurs at a solidification step of the molded article after molding. It was confirmed that the compositions of Comparative Examples 1 and 4, in which polylactic acid and styrene-acrylate copolymer were excluded, had poor bending properties. The composition of Comparative Example 4, which did not contain polyoxymethylene, had poor appearance due to the use of PA-6 (Polyamide-6).

Claims (8)

A resin composition comprising 10 to 90% by weight of polyoxymethylene, 1 to 50% by weight of polylactic acid, 0.05 to 5% by weight of a styrene-acrylate copolymer, and 5 to 50% by weight of glass fibers. delete The method according to claim 1,
Wherein the resin composition further comprises one or more of a thermal decomposition stabilizer, an antioxidant, and a compatibilizing agent. In paragraph 3,
Wherein the thermal decomposition stabilizer is ethylene vinyl alcohol (EVOH), a hydrazine type additive, or a mixture thereof. In paragraph 3,
Wherein the antioxidant is a hindered phenol-based oxidizing agent. In paragraph 3,
Wherein the compatibilizer is a bismaleimide triazine monomer, a polycarbonate resin or a mixture thereof. An injection molded article comprising the resin composition of claim 1. An extrusion molding comprising the resin composition of claim 1.

Images