KR102208253B1 - Polyamide Resin Composition for injection molding of thin product and molded product thererof - Google Patents

Abstract

In the case of injection molding into thin products using polyamide produced using raw materials produced through the bioconversion process, the properties of resins that are difficult to separate from the mold are improved to improve releasability and mechanical properties including boss stiffness. Disclosed are an improved polyamide resin composition and a molded article using the same. The present invention provides a polyamide resin composition for injection molding thin-walled products containing 10 to 50 parts by weight of glass fiber and 0.1 to 3 parts by weight of a lubricant, and a molded article using the same, based on 100 parts by weight of polyamide polymerized with pentamethylenediamine and sebacic acid. to provide.

Description

Polyamide Resin Composition for injection molding of thin product and molded product thererof

The present invention relates to a polyamide resin composition and a molded article thereof, and more particularly, to a polyamide resin composition for injection molding thin-walled products and a molded article thereof.

Polyamide (PA) is a representative crystalline synthetic resin as a generic term for linear polymers containing an amide group (-NH-CO-) in a molecular structure. Polyamide is a resin having high melting point and high strength physical properties by having a strong hydrogen bond between molecular chains by an amide group and linear properties and chain length of a polymer chain that is very easy to crystallize. It is widely applied in fields requiring high heat resistance and rigidity, such as electrical and electronic parts, and automotive parts materials.

In polyamide, the concentration of amide groups in the polymer chain varies depending on the structure of the polymerization raw material (monomer). Long-chain aliphatic polyamides such as PA12, PA610, and PA612, which have a relatively low concentration of amide groups, have low moisture absorption rates. Due to its high dimensional stability, oil resistance, and chemical resistance, it is easy to develop as a material for electronic devices.

Long-chain aliphatic polyamides such as PA610 and PA612, which are currently commercially produced, are prepared through condensation polymerization, and diamines having an even number of carbons such as hexamethylene diamine (HMDA) are mainly used as a polymerization raw material. This is because petrochemical-based diamine having an odd number of carbon atoms is difficult to use as a monomer of a polymer due to economic problems.

However, recently, the production of various kinds of diamine raw materials has begun to be possible through a bioconversion process, and among them, studies on the production of pentamethylenediamine (cadaverine, CAD) having an odd number of carbon atoms are actively being conducted. Pentamethyldiamine is a diamine with 5 carbon atoms, which can be biologically produced through decarbonation of lysine produced from biomass, and has economic feasibility that can be applied as a polymer monomer, so it is a raw material for biopolyamide resins such as PA56 and PA510. It can be used as, and by using it, it can be molded into products in various fields.

Korean Patent Publication No. 2009-0014260 discloses a polyamide resin composition for portable electronic devices, which has excellent mechanical strength, thin formability, crystallinity, and bendability, but injection molding when applied as a thin product of biomass-derived polyamide. There is no mention of sexual enhancement.

The present invention was conceived to solve the above problem, and when injection molding into a thin product using polyamide manufactured using raw materials produced through a bioconversion process, polyamide resin having excellent dimensional stability and improved impact resistance It is intended to provide a composition and a molded article using it.

In order to solve the above problems, the present invention provides a polyamide resin composition for injection molding thin-walled products containing 10 to 50 parts by weight of glass fiber, based on 100 parts by weight of polyamide polymerized with pentamethylenediamine and sebacic acid.

In addition, the polyamide is a polyamide resin for injection molding of thin-walled products, characterized in that the relative viscosity (RV, 98% (w/w) sulfuric acid as a solvent and a concentration of 1 g/dL analyzed at 25° C.) is 2.4 to 3.2. The composition is provided.

In addition, 0.1 to 3 parts by weight of a lubricant is further included based on 100 parts by weight of the polyamide, wherein the lubricant is an ethylene bis stearamide wax type lubricant, an acrylic ester type lubricant, and montan wax. A polyamide resin composition for injection molding of thin-walled products, characterized in that it is at least one selected from the group consisting of Montanwax type lubricants, Lico wax type lubricants, and Metal stearate type lubricants. to provide.

In addition, the polyamide resin composition provides a polyamide resin composition for injection molding thin products, characterized in that it further comprises 0.05 to 2 parts by weight of an antioxidant and 0.1 to 5 parts by weight of carbon black based on 100 parts by weight of the polyamide. .

In addition, the polyamide resin composition has an IZOD impact strength (ASTM D256, -30°C) of 5 kgf·cm/cm or more, an IZOD impact strength (ASTM D256, 23°C) of 15 kgf·cm/cm or more, and a shrinkage rate (ASTM D955) provides a polyamide resin composition for injection molding thin products, characterized in that 1% or less.

In order to solve the above another problem, the present invention provides a thin sheet having a thickness of 0.1 to 1 mm molded using the polyamide resin composition.

According to the present invention, as a polyamide monomer, when applied for injection molding purposes as a thin-walled product, a polyamide polymerized with biomass-derived pentamethylenediamine and biomass-derived sebacic acid in a specific content contains glass fiber and a lubricant. By having excellent thin-wall moldability and impact resistance compared to long-chain aliphatic polyamide products, it is possible to provide an eco-friendly long-chain aliphatic polyamide resin composition suitable for use in electronic device housings requiring light weight, thin-wall moldability, and impact resistance.

Hereinafter, a preferred embodiment of the present invention will be described in detail. In describing the present invention, when it is determined that a detailed description of a related known technology may obscure the subject matter of the present invention, a detailed description thereof will be omitted. Throughout the specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components, unless otherwise stated.

The present inventors have a characteristic that it is difficult to separate from the mold when thin-walled products are injection-molded using polyamide 510, and as a result of repeated research on a method to solve this problem as a 100% bio-derived polyamide, biomass as a monomer When the polyamide polymerized with the derived pentamethylenediamine and the biomass-derived sebacic acid contains a certain amount of glass fiber and lubricant, it can have excellent thin-walled moldability and impact resistance compared to the existing commercially produced long-chain aliphatic polyamide products. And came to the present invention.

Accordingly, the present invention discloses a polyamide resin composition for injection molding thin products comprising 10 to 50 parts by weight of glass fiber, based on 100 parts by weight of polyamide polymerized with pentamethylenediamine and sebacic acid, and preferably the polyamide Disclosed is a polyamide resin composition for injection molding thin-walled products further comprising 0.1 to 3 parts by weight of a lubricant based on 100 parts by weight.

Polyamide 510 resin is one of the long-chain aliphatic polyamide resins, and it is very expensive to produce pentamethylenediamine, which is a diamine component, which is a polymerization raw material, and it is difficult to commercially produce petrochemical-based polyamide resins. Although it was first developed with better physical properties than general-purpose polyamides such as PA6 and PA66, it was not easily commercialized.

However, recently, as pentamethylenediamine can be produced from biomass through a bioconversion process, the synthesis of polyamide using the same has been actively studied. Here, polyamide 510 using biomass-derived sebacic acid as a dicarboxylic acid component When manufacturing a resin, an eco-friendly polyamide resin of 100% bio-component can be manufactured. Eco-friendly polyamide resins can reduce the environmental burden by producing products that do not generate excess carbon dioxide, which is the main cause of global warming, and use biomass-derived raw materials that are much cheaper than raw materials produced using general petrochemical processes. Can lower the cost of production.

The 100% biopolyamide 510 resin containing pentamethyldiamine derived from biomass and sebacic acid derived from biomass as constituents can be prepared through condensation polymerization under high pressure. However, in case of injection molding using polyamide 510 alone for application to products, mechanical properties are insufficient to be applied to commercial products. In addition, when manufacturing a thin molded article such as a cell phone battery cover, there is a problem that it is easily broken in the process of releasing the injection product.

In the present invention, in order to overcome this problem, glass fiber-reinforced polyamide 510 resin with improved product moldability and mechanical properties was prepared by mixing glass fiber and lubricant with polyamide 510 resin, and a thin product that can be evaluated as an ICT material is molded. Thus, excellent dimensional stability and mechanical properties were confirmed.

In the present invention, glass fibers are used to reinforce thin-wall moldability and dimensional stability properties applicable to electronic device housings of polyamide 510 resin.

The glass fiber may be a sizing-treated glass fiber having a length of 1 to 10 mm, preferably 2 to 5 mm, for compatibility with polyamide, and at this time, glass fiber per 100 parts by weight of polyamide 510 resin 10 to 50 parts by weight may be used, and preferably 20 to 40 parts by weight may be used.

In addition, in the present invention, a lubricant is used to further improve dimensional stability of the polyamide 510 resin.

The lubricant is not particularly limited, for example, an ethylene bis stearamide wax type lubricant, an acrylic ester type lubricant, a Montanwax type lubricant, a Lico wax type. type) lubricant, metal stearate type lubricant, etc. may be used.

The lubricant may be used in an amount of 0.1 to 3 parts by weight, preferably 0.2 to 1 part by weight, more preferably 0.2 to 0.5 parts by weight, based on 100 parts by weight of the polyamide 510 resin. When the amount of the lubricant is less than 0.1 part by weight, thin-walled moldability is not good due to poor mold release, and when used in excessive amounts, problems of appearance defects due to deterioration of physical properties of the resin and generation of gas may occur.

In the present invention, antioxidants and carbon black may be used in the biomass-derived polyamide in addition to the glass fibers and lubricants.

As the antioxidant, a phenolic primary antioxidant and a phosphite secondary antioxidant may be used, and these additives act as a peroxide decomposition agent and removal of radicals generated by resin deterioration that may occur during the melt-kneading process. . The phenolic primary antioxidant and the phosphite secondary antioxidant may be used in an amount of 0.01 to 1 parts by weight, preferably 0.05 to 0.5 parts by weight, respectively, based on 100 parts by weight of the polyamide 510 resin.

In addition, the carbon black may be used for imparting color to the injection product, and may be used in an amount of 0.1 to 3 parts by weight, preferably 0.2 to 1 part by weight, based on 100 parts by weight of the polyamide 510 resin.

The polyamide resin composition according to the present invention containing the above components is applied for injection molding of thin-walled products, and in this case, it is light weight when applied for injection molding of thin-walled products having a thickness of 0.1 to 1 mm, preferably 0.3 to 0.6 mm. It can be particularly suitably applied to electronic device housings, such as cell phone battery covers, which require property, thin formability, and impact resistance.

In addition, in order to realize the above characteristics, the polyamide resin composition according to the present invention specifically has an IZOD impact strength (ASTM D256, -30°C) of 5 kgf·cm/cm or more, preferably 7 kgf·cm/cm or more, IZOD impact strength (ASTM D256, 23°C) is 15 kgf·cm/cm or more, preferably 17 kgf·cm/cm or more, and shrinkage (ASTM D955) is 1% or less, preferably 0.5% or less, more preferably It may be 0.3% or less.

Hereinafter, a method for preparing a polyamide resin composition for injection molding thin-walled products according to the present invention will be described in detail.

First, the polyamide 510 resin polymerized with pentamethylenediamine and sebacic acid may be prepared through condensation polymerization and solid phase polymerization in a molten state.

For example, pentamethylenediamine and sebacic acid are added in an equivalent ratio of 1.1 to 1.2 in a reactor sufficiently substituted with an inert gas such as nitrogen or argon. Each component is added separately or mixed in advance and then added simultaneously. However, it is preferable to put the diamine component dissolved in water, because it is advantageous in maintaining the equivalent ratio of raw materials by stably introducing the diamine component with strong volatility into the reaction system. Water is added in an amount of 50 to 60% by weight based on the total amount of raw materials. In polyamide, since the exothermic reaction of the reactants occurs rapidly at the initial stage of polymerization, polymerization in the presence of water is easier to control the initial reaction rate than the method of direct melt polymerization of the raw material.

Thereafter, the reaction product is heated up to 130 to 150°C and stirred to prepare a polyamide salt through an acid-base reaction, and then the polyamide salt is heated to 220 to 240°C and stirred while pre-polymerization is performed. . When the reaction product reaches a certain temperature or higher, the pressure inside the reaction system rises as water fills the inside of the reactor in a vapor state.At this time, a low molecular weight polyamide prepolymer ( pre-polymer). Thereafter, the water used as a solvent and the condensed water are slowly removed out of the system, and the internal pressure is lowered to normal pressure, and the prepolymer is discharged out of the system to cool.

The discharged prepolymer is pulverized and granulated into a size of 1.0 to 2.0 mm, followed by solid-phase polymerization. Solid-phase polymerization is a reaction that proceeds below the melting point of the polyamide 510 resin, thereby improving the problem of generation of cyclic by-products due to deammonia reaction and color discoloration due to high temperature, which occurs when manufacturing through melt polymerization under general high temperature and high pressure. I can. The solid-phase polymerization is carried out for 8 to 14 hours under vacuum at 180 to 200°C, and at this time, it is preferable to polymerize so that the relative viscosity (R.V.) of the polyamide 510 is in the range of 2.4 to 3.2. When the final molded product is manufactured with a resin having a relative viscosity of less than 2.4, the mechanical strength may be insufficient to be applied to commercial products, and when the relative viscosity is greater than 3.2, the flowability of the molten resin may be low, making it difficult to mold the product.

A melt-kneading method may be used to blend the fiber-reinforced polyamide resin composition using the polyamide 510 prepared by the above method.

As a method of introducing each component constituting the fiber-reinforced polyamide resin composition, a twin-screw extruder having two injection ports can be used. At this time, a method of supplying a polyamide 510 resin and a lubricant, a primary antioxidant, a secondary antioxidant and a carbon black component to the main inlet, and a glass fiber to the secondary inlet is preferred. When the glass fibers are added to the main inlet, it is difficult to uniformly mix the glass fibers in the process of melt-kneading, and the glass fibers may be damaged in the process of passing through the barrel of the extruder, thereby deteriorating the improvement of the mechanical strength of the final blended resin. The melt-kneaded resin can be cut into pellets after being discharged in the form of strands.

As described above, a polyamide resin composition was prepared by including glass fiber and a lubricant in a specific amount in a polyamide polymerized with biomass-derived pentamethylenediamine and biomass-derived sebacic acid as a polyamide monomer, but prepared by the method described above. In the case of using polyamide, it is possible to provide a manufacturing method that is particularly suitable to ensure that it has the same level of rigidity and thin-wall moldability as long-chain aliphatic polyamide products in commercial production when applied as a thin-walled product for injection molding purposes.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

First, the base resin and the comparative resin used in the examples and comparative examples were prepared as follows.

Base resin

Bio-derived sebacic acid and bio-derived pentamethylenediamine are added to a batch-type reactor connected to a stirrer and a condenser at a molar ratio of 1.0:1.2, and then water is added so that the added raw material is 53% by weight of the total reactants including water. At this time, sodium phosphinate, which is a catalyst, is simultaneously added, followed by mixing under a nitrogen stream, while raising the temperature in the reactor to about 140°C over about 70 minutes and stirring to prepare a polyamide salt. Thereafter, the reactor was heated to 230° C. and the internal pressure was maintained at 17 bar to polymerize the polyamide oligomer under high temperature and high pressure conditions for about 30 minutes. At this time, water in the form of steam is condensed through a condenser and removed to the outside of the reactor while maintaining the internal pressure. Thereafter, the internal pressure of the reaction system is gradually lowered to normal pressure to remove both the added water and the condensed water, and then the prepolymerized polyamide prepolymerized product in the form of a prepolymer that has been firstly polymerized is discharged. After the solid discharge was pulverized and granulated, the particles of 1.0 to 4.0 mm were sorted through a sieve and solid-phase polymerization was performed at 190° C. for 8 hours under vacuum. The relative viscosity (R.V.) of the final polymerized product was 2.8.

Comparison resin

Commercially produced Evonik's polyamide 610, polyamide 612 and KP Chemtech's polyamide 6 were used.

Example 1

Based on 100 parts by weight of the base resin, 0.3 parts by weight of a lubricant (Ethylene Bis Stearamide wax type lubricant), 0.1 parts by weight of a phenolic primary antioxidant (IRGANOX 1098), 0.1 parts by weight of a secondary antioxidant (IRGAFOS 168) and 0.5 parts by weight of carbon black The weight part was mixed and put into the main inlet of a twin screw extruder. In addition, 30 parts by weight of polyamide-only glass fibers having a length of 4 mm were put into the sub-inlet and melt-kneaded, and the mixed extrudate was molded into strands through an extruder, and then cut to prepare a pelletized polyamide resin composition.

The prepared polyamide resin composition was prepared in a thickness of 0.4 mm for evaluation of physical properties using a Sumitomo electric injection machine at 230 ~ 250 ℃.

Comparative Example 1

A polyamide resin composition and specimen were prepared in the same manner as in Example 1, except that the comparative resin polyamide 610 was used in Example 1.

Comparative Example 2

In Example 1, a polyamide resin composition and a specimen were prepared in the same manner as in Example 1, except that the comparative resin, polyamide 612 was used.

Comparative Example 3

In Example 1, a polyamide resin composition and a specimen were prepared in the same manner as in Example 1, except that the comparative resin, polyamide 6 was used.

Test example

For the specimens prepared according to the Examples and Comparative Examples, impact strength and shrinkage were measured by the following method, and the results are shown in Table 1 below.

[How to measure]

(1) IZOD impact strength (-30℃ and 23℃)

According to ASTM D256, the energy required to cause breakage was measured when a 3T-thick test piece supported in a vertical state was hit with a pendulum and destroyed.

(2) shrinkage rate

A tensile test specimen prepared according to ASTM evaluation method D638 was measured through a microscope. The shrinkage rate was calculated according to Equation 1 below by measuring the distance between the marks of the injection-molded specimen compared to the reference mark distance predefined in the specimen mold.

[Equation 1]

Referring to Table 1, as a polyamide monomer according to the present invention, a polyamide polymerized with biomass-derived pentamethylenediamine and biomass-derived sebacic acid contains glass fiber and a lubricant in a specific amount, but prepared by the specific method In the case of manufacturing a fiber-reinforced polyamide resin composition using polyamide, when applied as a thin-walled product for injection molding purposes (Example 1) Long-chain aliphatic polyamide products (Comparative Examples 1 and 2) and general-purpose polyamides in commercial production Compared to the product (Comparative Example 3), it was confirmed that the thin-walled moldability and the impact resistance properties at low and room temperature were excellent. From this, the present invention can provide an eco-friendly long-chain aliphatic polyamide resin composition capable of implementing various physical properties suitable for an electronic device housing such as light weight, excellent thin-wall moldability, and impact resistance while utilizing 100% biomass-derived components as a base resin. In addition, since it is manufactured using biomass-derived raw materials, the environmental load due to reduction of carbon dioxide generation is low, and the production cost of the polymerization raw material produced by the bioconversion process is reduced, making it possible to economically manufacture the final polymerization resin. have.

The preferred embodiments of the present invention have been described in detail above. The description of the present invention is for illustration only, and those of ordinary skill in the art to which the present invention pertains will be able to understand that other specific forms can be easily modified without changing the technical spirit or essential features of the present invention.

Accordingly, the scope of the present invention is indicated by the claims to be described later rather than the description of the invention, and all changes or modified forms derived from the meaning, scope and equivalent concepts of the claims are interpreted as being included in the scope of the present invention. Should be.

Claims (6)

With respect to 100 parts by weight of polyamide polymerized with pentamethylenediamine and sebacic acid, 10 to 50 parts by weight of glass fibers are included, wherein the polyamide has a relative viscosity (RV, 98% (w/w) sulfuric acid in a concentration of 1 g as a solvent) A polyamide resin composition for injection molding of thin-walled products, characterized in that the analysis at 25°C at /㎗) is 2.4 to 3.2. delete The method of claim 1,
Further comprising 0.1 to 3 parts by weight of a lubricant based on 100 parts by weight of the polyamide, the lubricant is an ethylene bis stearamide (Ethylene Bis Stearamide) wax type lubricant, acrylic ester type (Acrylic ester type) lubricant, Montan wax type ( Montanwax type) a lubricant, a Lico wax type (Lico wax type) lubricant, and a metal stearate type (Metal stearate type) lubricant, characterized in that at least one selected from the group consisting of a polyamide resin composition for injection molding thin products. The method of claim 1,
The polyamide resin composition further comprises 0.05 to 2 parts by weight of an antioxidant and 0.1 to 5 parts by weight of carbon black based on 100 parts by weight of the polyamide. A polyamide resin composition for injection molding thin-walled products containing 10 to 50 parts by weight of glass fiber based on 100 parts by weight of polyamide polymerized with pentamethylenediamine and sebacic acid, wherein the polyamide resin composition has IZOD impact strength (ASTM D256, For injection molding of thin-walled products, characterized in that -30℃ is 5 kgf·cm/cm or more, IZOD impact strength (ASTM D256, 23℃ is 15 kgf·cm/cm or more, and shrinkage (ASTM D955) is less than 1%) Polyamide resin composition. A thin sheet having a thickness of 0.1 to 1 mm formed using the polyamide resin composition of any one of claims 1, 3 to 5.