Polybutylene terephthalate resin composition, its manufacturing method, and molded article manufactured therefrom

Abstract

The present invention relates to a polybutylene terephthalate resin composition, a manufacturing method thereof, and a molded article manufactured from the same, which provides an excellent balance of physical properties, namely mechanical strength and flame retardancy, equivalent to or higher than that of polyester resin composite materials containing halogen-based flame retardants, and has excellent processability due to its excellent fluidity, and is particularly suitable as a material for automotive electrical components.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0117051 filed on September 16, 2022, and Korean Patent Application No. 10-2023-0087762, refiled on July 6, 2023 based thereon, and all contents disclosed in the documents of said Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a polybutylene terephthalate resin composition, a method for producing the same, and a molded article produced therefrom. More specifically, the present invention relates to a polybutylene terephthalate resin composition that does not contain a halogen-based flame retardant but has an excellent balance of mechanical properties and flame retardancy, a method for producing the same, and a molded article produced therefrom. [Background technology]

[0003] In the automotive field, research is being actively conducted to replace materials used in parts with plastics in order to reduce weight and manufacturing costs.

[0004] Among plastics, polyester resins are widely used as materials for automobile parts and are considered to have the potential to replace aluminum and steel. As a result, polybutylene terephthalate resin, a type of polyester resin, is excellent in terms of high rigidity and heat resistance, and research into its application to various automobile parts is actively underway.

[0005] However, in order to use polybutylene terephthalate resin as a material for electrical components, especially connector components, it is necessary to develop a flame-retardant composite material that includes a non-halogen flame retardant.

[0006] Metal salt phosphorus-based flame retardants are mainly used as non-halogen flame retardants in polybutylene terephthalate resin composite materials, but it is difficult to achieve the same level of mechanical rigidity and flame retardancy as when halogen-based flame retardants are used. Therefore, there is a need to develop polybutylene terephthalate resin compositions that contain non-halogen flame retardants but still have excellent mechanical rigidity and flame retardancy. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent Publication No. 10-2011-0072828 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a polybutylene terephthalate resin composition that achieves a balance of mechanical strength and flame retardancy at a level suitable for use as a material for automobile parts, and a method for producing the same.

[0009] Another object of the present invention is to provide a molded article produced from the polybutylene terephthalate resin composition.

[0010] The above and other objects of the present invention can all be achieved by the present invention described below. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention provides I) a polybutylene terephthalate resin composition comprising polybutylene terephthalate, an aluminum salt of diethylphosphinic acid, melamine polyphosphate, and a silica-containing reinforcing agent, and characterized in that the composition satisfies the following mathematical formula 1:

[0012] [Formula 1] 7.76≦a / b≦45 (In the above formula 1, a is the tensile strength (MPa) of the polybutylene terephthalate resin composition measured according to ISO 527, and b is the flow index (g / 10 min) of the polybutylene terephthalate resin composition measured according to ISO 1133 at 265°C under a load of 2.16 kg.)

[0013] II) In I), the silica-containing reinforcing agent may contain 50% or more by weight of silica in the reinforcing agent, specifically 50 to 70% by weight, preferably 50 to 65% by weight, and more preferably 50 to 60% by weight.

[0014] III) In I) or II), when the content of the polybutylene terephthalate is c and the content of the silica-containing reinforcing agent is d, the correlation of 0.5d≦c≦2d can be satisfied.

[0015] Here, the content may refer to % by weight based on a total of 100% by weight of polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, and silica-containing reinforcing agent, and if necessary, may further include at least one selected from melamine cyanurate, polyethylene, processability improver, and heat resistance additive, and refers to % by weight based on a total of 100% by weight.

[0016] IV) In I) to III), the polybutylene terephthalate may be contained in an amount within a range of 15 to 65% by weight relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent; or the polybutylene terephthalate resin composition may contain a processability improver and a heat resistance additive, and the polybutylene terephthalate may be contained in an amount within a range of 15 to 65% by weight relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent, the processability improver, and the heat resistance additive.

[0017] V) In the above I) to IV), the polybutylene terephthalate may have an intrinsic viscosity (η) of 0.5 to 1.25 dl / g as measured in accordance with ASTM D2857.

[0018] VI) In I) to V), the silica-containing reinforcing agent is contained in an amount within a range of 10 to 50% by weight, relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent; or the polybutylene terephthalate resin composition may contain a processability improver and a heat resistance additive, and the silica-containing reinforcing agent is contained in an amount within a range of 10 to 50% by weight, relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, the processability improver, and the heat resistance additive.

[0019] VII) In I) to VI), the aluminum salt of diethylphosphinic acid is contained in a range of 5 to 35% by weight relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, melamine polyphosphate, and the silica-containing reinforcing agent; or the polybutylene terephthalate resin composition may contain a processability improver and a heat resistance additive, and the aluminum salt of diethylphosphinic acid is contained in a range of 5 to 35% by weight relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, melamine polyphosphate, and the silica-containing reinforcing agent, the processability improver, and the heat resistance additive.

[0020] VIII) In I) to VII), the melamine polyphosphate is contained in an amount within the range of 0.1 to 10% by weight relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent; or the polybutylene terephthalate resin composition may contain a processability improver and a heat resistance additive, and the melamine polyphosphate is contained in an amount within the range of 0.1 to 10% by weight relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent, the processability improver, and the heat resistance additive.

[0021] IX) In any of I) to VIII), the resin composition may contain melamine cyanurate in an amount of 0.1 to 10% by weight relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, and the melamine cyanurate; or the polybutylene terephthalate resin composition may contain a processability improver and a heat resistance additive in an amount of 0.1 to 10% by weight relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, the melamine cyanurate, the processability improver, and the heat resistance additive.

[0022] X) In the above I) to IX), the resin composition may contain a processability improver, and the processability improver may be contained in an amount of 0.001 to 3 wt % based on a total of 100 wt % of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, and the processability improver.

[0023] XI) In the above I) to X), the resin composition may contain a heat-resistant additive, and the heat-resistant additive may be contained in an amount of 0.001 to 3% by weight based on a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, and the heat-resistant additive.

[0024] The present invention also provides XII) a method for producing a polybutylene terephthalate resin composition, which comprises the steps of kneading and extruding polybutylene terephthalate, an aluminum salt of diethylphosphinic acid, melamine polyphosphate, and a silica-containing reinforcing agent, and is characterized by satisfying the following mathematical formula 1:

[0025] [Formula 1] 7.76≦a / b≦45 (In the above formula 1, a is the tensile strength (MPa) of the polybutylene terephthalate resin composition measured according to ISO 527, and b is the flow index (g / 10 min) of the polybutylene terephthalate resin composition measured according to ISO 1133 at 265°C under a load of 2.16 kg.)

[0026] The present invention also includes XIII) a molded article comprising the polybutylene terephthalate resin composition described above.

[0027] XIV) In the above XIII), the molded article may be an automobile electrical component. [Effects of the Invention]

[0028] The polybutylene terephthalate resin composition according to the present invention provides an excellent balance of physical properties, namely, mechanical strength and flame retardancy, at a level equivalent to or even higher than that of polyester resin composite materials containing halogen-based flame retardants, and has excellent processability due to its excellent fluidity, and can be used as a material for automotive electrical components in particular.

[0029] That is, the molded article produced from the polybutylene terephthalate resin composition according to the present invention has an advantage in that a high level of balance between mechanical properties such as tensile strength and flame retardancy is realized.

[0030] Therefore, the polybutylene terephthalate resin composition according to the present invention and the molded articles produced therefrom can be widely applied to the field of automobile parts where such are required. BEST MODE FOR CARRYING OUT THE INVENTION

[0031] The present invention will now be described in more detail to aid in understanding the invention.

[0032] The terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, taking into consideration that the inventor may define the concept of terms as appropriate in order to best describe the invention.

[0033] The present inventors have confirmed that by adjusting the type and content of non-halogen flame retardants, it is possible to achieve a balance of mechanical strength and flame retardancy suitable for automotive parts materials, and have completed the present invention.

[0034] The polybutylene terephthalate resin composition according to the present invention comprises polybutylene terephthalate, an aluminum salt of diethylphosphinic acid, melamine polyphosphate, and a silica-containing reinforcing agent.

[0035] When the tensile strength (MPa) measured according to ISO 527 is defined as a and the flow index (g / 10 min) measured according to ISO 1133 at 265°C under a load of 2.16 kg is defined as b, the polybutylene terephthalate resin composition can have a ratio a / b that is, for example, in the range of 7.76 to 45, specifically 7.76 to 40, and preferably 7.77 to 40. When the ratio is in the above range, a balance of physical properties such as rigidity, flame retardancy, and processability can be provided.

[0036] In one embodiment of the present invention, the a may be 130 or more, or 130-165, and the b may be 4-20, or 4-18.

[0037] Each component of the polybutylene terephthalate resin composition of the present invention will be described in detail below.

[0038] <Polybutylene terephthalate> In one embodiment of the present invention, the polybutylene terephthalate may be polybutylene terephthalate obtained by direct esterification or transesterification of 1,4-butanediol with terephthalic acid or dimethyl terephthalate to cause polycondensation.

[0039] In one embodiment of the present invention, in order to increase the impact strength of the polybutylene terephthalate resin composition, the polybutylene terephthalate may be a copolymer copolymerized with an impact improving compound such as polytetramethylene glycol, polyethylene glycol, polypropylene glycol, aliphatic polyester, aliphatic polyamide, etc., or the polybutylene terephthalate may be a modified polybutylene terephthalate mixed with the impact improving compound.

[0040] In one embodiment of the present invention, the intrinsic viscosity η of the polybutylene terephthalate measured in accordance with ASTM D2857 may be, for example, 0.5 to 1.25 dL / g, preferably 0.5 to 1.2 dL / g, and more preferably 0.52 to 1 dL / g. When the intrinsic viscosity of the polybutylene terephthalate satisfies the above range, a polybutylene terephthalate resin composition having an excellent balance of physical properties between mechanical properties and moldability can be obtained.

[0041] In one embodiment of the present invention, the polybutylene terephthalate is contained in an amount of 15 to 65 wt %, 25 to 58 wt %, preferably 40 to 58 wt %, more preferably 40 to 55 wt %, and even more preferably 45 to 55 wt %, relative to 100 wt % of the total of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent; or the polybutylene terephthalate resin composition may contain a processability improver and a heat resistance additive, and the polybutylene terephthalate is contained in an amount of 15 to 65 wt %, 25 to 58 wt %, preferably 40 to 58 wt %, more preferably 40 to 55 wt %, and even more preferably 45 to 55 wt %, relative to 100 wt % of the total of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent, the processability improver, and the heat resistance additive. When the polybutylene terephthalate is contained within the above range, it is possible to provide a polybutylene terephthalate resin composition having an excellent balance of processability, specific gravity, and mechanical properties.

[0042] <Reinforcer> In one embodiment of the present invention, the reinforcing agent may be, for example, glass fiber, and the reinforcing agent may be used together with other inorganic fibers.

[0043] In this case, the inorganic fiber may be, for example, one or more selected from carbon fiber, basalt fiber, and natural fiber such as kenaf or hemp.

[0044] In one embodiment of the present invention, the cross section of the reinforcing agent may have a shape such as a circle, a rectangle, an oval, a dumbbell, or a diamond, and may have an average diameter of 8 to 20 μm or 10 to 15 μm and an average length of 2 to 6 mm or 2 to 4 mm.

[0045] The average diameter and average length of the reinforcing agent can be measured by a method commonly used in this technical field. For example, the reinforcing agent can be observed under a scanning electron microscope (SEM) and the average diameter and average length of 10 to 30 strands can be measured.

[0046] The reinforcing agents may be treated with sizing compositions during fiber manufacture or in post-treatment steps, including processing aids, coupling agents, surfactants, and the like.

[0047] The processing improver is mainly used to form good strands, and the coupling agent enables good adhesion between the toughening agent and the polybutylene terephthalate resin. When appropriately selected and used in consideration of the types of polybutylene terephthalate resin and toughening agent, the coupling agent can impart excellent physical properties to the polybutylene terephthalate resin composition.

[0048] The coupling agent can be used by directly treating it with a reinforcing agent or by adding it to an organic matrix. In order to fully utilize the performance of the coupling agent, the content of the coupling agent must be appropriately selected.

[0049] Examples of the coupling agent include amine-based, acrylic-based, and silane-based agents such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)γ-aminopropyltriethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and β(3,4-epoxyethyl)γ-aminopropyltrimethoxysilane.

[0050] In particular, the reinforcing agent described herein preferably contains silica, as this can provide rigidity and mechanical properties.

[0051] The silica may be contained in the reinforcing agent in an amount of, for example, 50% by weight or more, specifically 50 to 70% by weight, preferably 50 to 65% by weight, and more preferably 50 to 60% by weight. When the amount is within the above range, an excellent balance between rigidity and mechanical properties can be provided.

[0052] Specifically, as can be seen from the following examples and comparative examples, when a reinforcement agent with an inappropriate content of silica, for example 48 wt%, was used instead, the flame retardancy was excellent, but the tensile strength and flow index were poor, and it was confirmed that a balance of physical properties could not be achieved (see Comparative Example 4).

[0053] In the present invention, the silica content in the reinforcing agent can be measured or confirmed using XRF (X-ray fluorescence spectrometry).

[0054] In one embodiment of the present invention, the silica-containing reinforcing agent is contained in an amount of 10 to 50% by weight, preferably 15 to 50% by weight, and more preferably 20 to 50% by weight, relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent; or the polybutylene terephthalate resin composition may also contain a processability improver and a heat resistance additive, and the silica-containing reinforcing agent is contained in an amount of 10 to 50% by weight, preferably 15 to 50% by weight, and more preferably 20 to 50% by weight, relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, the processability improver, and the heat resistance additive.

[0055] <Non-halogen flame retardants> The non-halogen flame retardant according to the present invention may include an aluminum salt of diethylphosphinic acid and melamine polyphosphate, and not only provides a flame retardant effect during extrusion and injection processing of the polybutylene terephthalate resin composition, but also provides sufficient flame retardant effect during long-term storage of the polybutylene terephthalate resin composition.

[0056] The aluminum salt of diethylphosphinic acid can form char on the surface of the polymer, thereby improving the flame retardancy of the composition.

[0057] In one embodiment of the present invention, the aluminum salt of diethylphosphinic acid may be a commercially available product.

[0058] For example, the aluminum salt of diethylphosphinic acid may be present in an amount of 5 to 35 wt %, 10 to 30 wt %, specifically 10 to 25 wt %, and preferably 10 to 20 wt %, based on 100 wt % of the total weight of the polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, and silica-containing reinforcing agent. Alternatively, the polybutylene terephthalate resin composition may contain a processability improver and a heat resistance additive, and the aluminum salt of diethylphosphinic acid may be present in an amount of 5 to 35 wt %, 10 to 30 wt %, specifically 10 to 25 wt %, and preferably 10 to 20 wt %, based on 100 wt % of the total weight of the polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, and silica-containing reinforcing agent, processability improver, and heat resistance additive. When the amount satisfies the above range, char may be formed on the surface of the polymer, improving the flame retardancy of the composition.

[0059] When the melamine polyphosphate is used simultaneously with the aluminum salt of diethylphosphinic acid, it can form char on the surface of the polymer together with the aluminum salt of diethylphosphinic acid, thereby improving the effect of protecting the polymer from combustion.

[0060] In one embodiment of the present invention, the melamine polyphosphate may be a commercially available product.

[0061] The melamine polyphosphate may be present in an amount of, for example, 0.1 to 10 wt %, specifically 0.1 to 5 wt %, preferably 1 to 5 wt %, and more preferably 2 to 4 wt %, based on a total of 100 wt % of the polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, and silica-containing reinforcing agent. Alternatively, the polybutylene terephthalate resin composition may contain a processability improver and a heat resistance additive, and the melamine polyphosphate may be present in an amount of, for example, 0.1 to 10 wt %, specifically 0.1 to 5 wt %, preferably 1 to 5 wt %, and more preferably 2 to 4 wt %, based on a total of 100 wt % of the polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, and silica-containing reinforcing agent, processability improver, and heat resistance additive. When the above-mentioned range is satisfied, sufficient char can be formed on the surface of the polymer, improving the flame retardancy of the composition.

[0062] According to an embodiment of the present invention, melamine cyanurate may be included, in which case, an inert gas may be generated to improve flame retardancy.

[0063] The melamine cyanurate is contained in an amount of, for example, 0.1 to 10% by weight, specifically 0.1 to 4.5% by weight, preferably 0.1 to 3.5% by weight, and more preferably 1 to 3.5% by weight, relative to 100% by weight of the total of polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, silica-containing reinforcing agent, and melamine cyanurate; or the polybutylene terephthalate resin composition may contain a processability improver and a heat resistance additive, and be contained in an amount of, for example, 0.1 to 10% by weight, specifically 0.1 to 4.5% by weight, preferably 0.1 to 3.5% by weight, and more preferably 1 to 3.5% by weight, relative to 100% by weight of the total of polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, silica-containing reinforcing agent, and melamine cyanurate combined with the processability improver and heat resistance additive.

[0064] <Processability improver> The processability improver according to the present invention may be an olefin wax, which serves to maintain excellent mold releasability and injectability of the polybutylene terephthalate resin composition.

[0065] The olefin wax may be a polymer having a low melt viscosity and an oily solid phase having slipperiness and plasticity. For example, the olefin wax may be one or more waxes selected from polyethylene wax and polypropylene wax, and commercially available products may be used.

[0066] For example, the processability improver may be polyethylene, and specific examples thereof include polyethylene having a drop point of 100 to 120°C, a melting point (mp) of 95 to 115°C, and a density (23°C) of 0.9 to 1.0 g / cm. 3 Absolute viscosity (120°C) is 350 to 450mm 2 In this case, it is possible to effectively provide mold releasability and injectability.

[0067] In this description, the drop point is indicated as the lowest temperature at which a lubricant changes into a liquid state due to an increase in temperature, as determined by an experimental method in accordance with ASTM D566 and KS M 2033. More specifically, the drop point can be indicated by placing a sample in a specified cup with a diameter of 100 mm, heating it under the specified conditions, and measuring the temperature at which the grease drops.

[0068] In this description, the melting point can be measured using a differential scanning calorimeter (DSC) manufactured by TA Corporation (2920). Specifically, the melting point can be measured by equilibrating the DSC at 0°C, increasing the temperature by 20°C per minute to 180°C, decreasing the temperature by 20°C per minute to -60°C, and then increasing the temperature by 10°C per minute to 180°C. The melting point is determined by measuring the peak region of the endothermic curve during the second temperature increase.

[0069] In this description, the density can be measured, for example, according to the measurement method of ASTM D1505.

[0070] In this description, the absolute viscosity can be measured using an absolute viscometer manufactured by Brookfield. As a specific example of the measurement, the absolute viscosity can be measured using an absolute viscometer LVT230 manufactured by Brookfield in accordance with the method of ASTM D1986-14.

[0071] As a specific example, the processability improver has a drop point of 105 to 115°C, a melting point (mp) of 100 to 110°C, and a density (23°C) of 0.95 to 1.0 g / cm 3 Absolute viscosity (120°C) is 380 to 420mm 2 Polyethylene with a tensile strength of 1 / 2 mm can be used.

[0072] As a specific example, the processability improver has a drop point of 108 to 112°C, a melting point (mp) of 102 to 106°C, and a density (23°C) of 0.95 to 0.98 g / cm 3 Absolute viscosity (120°C) is 400 to 420mm 2 Polyethylene waxes having a viscosity of 1000 MPa or less can be used.

[0073] In one embodiment of the present invention, the processability improver may be a commercially available product, such as LC102N.

[0074] In one embodiment of the present invention, the processability improver is contained in a range of, for example, 0.001 to 3 wt %, preferably 0.05 to 3 wt %, more preferably 0.01 to 3 wt %, and most preferably 0.01 to 1 wt %, based on a total of 100 wt % of the polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, silica-containing reinforcing agent, and processability improver; or the polybutylene terephthalate resin composition may contain melamine cyanurate, and the processability improver may be contained in a range of, for example, 0.001 to 3 wt %, preferably 0.05 to 3 wt %, more preferably 0.01 to 3 wt %, and most preferably 0.01 to 1 wt %, based on a total of 100 wt % of the polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, polyethylene, silica-containing reinforcing agent, melamine cyanurate, and processability improver. When the above-mentioned range is satisfied, excellent mold release properties and injectability can be sufficiently provided.

[0075] As a specific example, the resin composition may contain polyethylene, and the polyethylene may be contained in an amount of, for example, 0.001 to 3% by weight, preferably 0.05 to 3% by weight, more preferably 0.01 to 3% by weight, and most preferably 0.01 to 1% by weight, relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, melamine polyphosphate, the silica-containing reinforcing agent, and the polyethylene; or the polybutylene terephthalate resin composition may contain polyethylene, melamine cyanurate, and a heat-resistant additive, and the polyethylene may be contained in an amount of, for example, 0.001 to 3% by weight, preferably 0.05 to 3% by weight, more preferably 0.01 to 3% by weight, and most preferably 0.01 to 1% by weight, relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, melamine polyphosphate, the polyethylene, the silica-containing reinforcing agent, the polyethylene, the melamine cyanurate, and the heat-resistant additive.

[0076] <Heat-resistant additive> The heat-resistant additive according to the present invention can provide the polybutylene terephthalate resin composition with an antioxidant effect at high temperatures during extrusion and injection processing.

[0077] The heat resistance additive may be, for example, two or more selected from a hindered phenol-based compound, a phosphite-based compound, and a phosphonite-based compound.

[0078] As the hindered phenol compound, commercially available products may be used.

[0079] Examples of the hindered phenolic compound include octadecyl-3-(4-hydroxy-3,5-di-tert-butylphenyl)propionate, tetrabis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, and the like. Examples of suitable hydroxybenzyl compounds include 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, and pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), with the use of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate being preferred.

[0080] Examples of the phosphite compound include triphenyl phosphite, tris(nonylphenyl)phosphite, triisodecyl phosphite, diphenyl-isooctyl-phosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, and tris(2,4-di-tert-butylphenyl)phosphite, and it is preferable to use tris(2,4-di-tert-butylphenyl)phosphite.

[0081] The phosphonite-based compound may be a compound represented by the following Chemical Formula 1:

[0082] [ka]

[0083] In the above formula 1, R1 and R2 each independently represent alkyl, aryl, or alkylaryl, and specifically represent C1-C 30 Alkyl, C6-C 30 Aryl or alkylaryl, where Ar is an aryl group such as phenyl, naphthyl, biphenyl, terphenyl, and the like.

[0084] As another example, the heat-resistant additive may be a mixture of a compound represented by the following Chemical Formula 2 and a compound represented by the following Chemical Formula 3:

[0085] When a compound represented by the following chemical formula 2 and a compound represented by the following chemical formula 3 are mixed, it is preferable that the density is, for example, 530 g / L or more, specifically 530 to 630 g / L, in order to provide an antioxidant effect at high temperatures.

[0086] Here, the density may be a value measured using a method and equipment commonly used in this technical field.

[0087] In one embodiment of the present invention, a commercially available product may be used, for example, a product such as B-225.

[0088] [ka]

[0089] [ka]

[0090] In one embodiment of the present invention, the heat-resistant additive may be contained in a range of, for example, 0.001 to 3 wt %, preferably 0.05 to 2 wt %, more preferably 0.01 to 2 wt %, and even more preferably 0.1 to 2 wt %, based on a total of 100 wt % of the polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, silica-containing reinforcing agent, and heat-resistant additive. When the above range is satisfied, thermal stability can be provided during high-temperature processing.

[0091] The heat-resistant additive may be contained in an amount of, for example, 0.001 to 3% by weight, preferably 0.05 to 2% by weight, more preferably 0.01 to 2% by weight, and even more preferably 0.1 to 2% by weight, based on a total of 100% by weight of the polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, silica-containing reinforcing agent, melamine cyanurate, and heat-resistant additive.

[0092] The heat-resistant additive may be contained in an amount of, for example, 0.001 to 3% by weight, preferably 0.05 to 2% by weight, more preferably 0.01 to 2% by weight, and even more preferably 0.1 to 2% by weight, based on a total of 100% by weight of the polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, silica-containing reinforcing agent, melamine cyanurate, polyethylene, and heat-resistant additive.

[0093] <Polybutylene terephthalate resin composition> The polybutylene terephthalate resin composition according to the present invention comprises polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, and a silica-containing reinforcing agent, and satisfies a correlation of 0.5d≦c≦2d, specifically d≦c≦2d, and preferably 1.3d≦c≦1.8d, where c is the content of the polybutylene terephthalate and d is the content of the silica-containing reinforcing agent. When the above ranges are satisfied, an excellent balance of physical properties, including rigidity, mechanical properties, and flame retardancy, can be provided.

[0094] The term "content" used in this description may refer to a unit of weight percent unless otherwise specified. Specifically, the contents of c and d may be weight percents contained in a total of 100 weight percent of the polybutylene terephthalate, aluminum salt of diethylphosphinic acid, melamine polyphosphate, silica-containing reinforcing agent, processability improver, and heat resistance additive.

[0095] Here, c may be, for example, an integer of 35 to 58, preferably an integer of 40 to 58, more preferably an integer of 40 to 55, and even more preferably an integer of 45 to 50. When the above-mentioned range is satisfied, an excellent balance of physical properties between rigidity, mechanical properties, and flame retardancy can be provided.

[0096] Furthermore, the d may be, for example, an integer of 10 to 50, preferably an integer of 15 to 50, and more preferably an integer of 20 to 50. When the d satisfies the above range, an excellent balance of physical properties between rigidity, mechanical properties, and flame retardancy can be provided.

[0097] In one embodiment of the present invention, the polybutylene terephthalate resin composition may include 15-65 wt% of polybutylene terephthalate; 10-50 wt% of a silica-containing reinforcing agent; 5-35 wt% of an aluminum salt of diethylphosphinic acid; 0.1-10 wt% of melamine polyphosphate; 0-10 wt% of melamine cyanurate; 0.001-3 wt% of a heat resistance additive; and 0.001-3 wt% of a processability improver.

[0098] As another example, the polybutylene terephthalate resin composition may include 35 to 58 wt% polybutylene terephthalate; 15 to 50 wt% silica-containing reinforcing agent; 10 to 25 wt% aluminum salt of diethylphosphinic acid; 0.1 to 5 wt% melamine polyphosphate; 0 to 4.5 wt% melamine cyanurate; 0.001 to 3 wt% heat resistance additive; and 0.001 to 3 wt% processability improver.

[0099] As another example, the polybutylene terephthalate resin composition may contain 40 to 58 wt% polybutylene terephthalate, 20 to 50 wt% silica-containing reinforcing agent, 10 to 20 wt% aluminum salt of diethylphosphinic acid, 1 to 5 wt% melamine polyphosphate, 0.1 to 10 wt% melamine cyanurate, 0.05 to 2 wt% heat resistance additive, and 0.05 to 3 wt% processability improver. When the above ranges are satisfied, an excellent balance of physical properties, including rigidity, mechanical properties, and flame retardancy, can be provided.

[0100] The polybutylene terephthalate resin composition may contain, for example, one or more additives selected from a UV stabilizer, a pigment, and a colorant, for example, in an amount of 0.01 to 5 parts by weight, preferably 0.5 to 2 parts by weight, and more preferably 1 to 2 parts by weight, based on 100 parts by weight of the polybutylene terephthalate resin composition. Within this range, the physical properties of the resin composition are not affected, and the additive's inherent properties are effectively expressed.

[0101] <Method of producing polybutylene terephthalate resin composition> The polybutylene terephthalate resin composition according to the present invention may be prepared by a method known in the art. For example, the polybutylene terephthalate resin composition may be prepared into pellets by melt-extruding a mixture of each component and other additives in an extruder, and the pellets may be used for injection and extrusion molded articles.

[0102] In one embodiment of the present invention, the pellets are preferably extruded at a temperature of 240 to 280° C., and the temperature of the mold during extrusion is preferably in the range of 80 to 120° C. If the temperature of the mold is less than 80° C., the appearance characteristics may be deteriorated, and if the temperature exceeds 120° C., the pellets may stick to the mold, reducing demoldability and increasing the cooling rate.

[0103] For example, a method for producing the polybutylene terephthalate resin composition of the present invention may include the steps of kneading and extruding polybutylene terephthalate, an aluminum salt of diethylphosphinic acid, melamine polyphosphate, and a silica-containing reinforcing agent, and optionally including the aforementioned melamine cyanurate.

[0104] In the kneading and extruding steps, the screw rotation speed of the extruder may be, for example, 150 to 330 rpm, 150 to 300 rpm, or 200 to 250 rpm. As long as the value satisfies the above range, the rigidity and processability can be improved as the value is lower.

[0105] The feed rate per hour (F / R) of the polybutylene terephthalate resin composition fed into the extruder is 70 kg / hr or less, preferably 60 kg / hr or less, more preferably 50 kg / hr or less, and even more preferably 45 to 55 kg / hr. In this case, a good balance of physical properties including rigidity, processability, and specific gravity can be achieved.

[0106] <Molded products> According to another embodiment of the present invention, there is provided a molded article made from the polybutylene terephthalate resin composition described above.

[0107] The molded product may be, for example, an automotive electrical component.

[0108] The molded article may be, for example, an automobile connector.

[0109] The molded article may have a tensile strength measured in accordance with ISO 527 of 130 MPa or more, or 135 to 165 MPa.

[0110] The molded article may have a flow index of 4 to 20 g / 10 min, or 4 to 18 g / min, measured in accordance with ISO 1133 at 265° C. under a load of 2.16 kg.

[0111] The molded article may have a flame retardancy (burning time / 5 pieces) of 50 seconds or less for 0.8 mm test pieces measured in accordance with UL 94.

[0112] In describing the polybutylene terephthalate resin composition, its production method, and molded articles described herein, it is clearly stated that other conditions, equipment, etc. not explicitly described can be appropriately selected within the range commonly used in the art and are not particularly limited.

[0113] The present invention will now be described in detail with reference to exemplary embodiments thereof so that those skilled in the art can easily practice the invention. However, the present invention may be embodied in various different forms and should not be construed as being limited to the exemplary embodiments set forth herein.

[0114] [Example] In one embodiment of the present invention, the components used to prepare the polybutylene terephthalate resin composition are as follows: (A) Polybutylene terephthalate (PBT: intrinsic viscosity 0.5 to 1 dl / g) (B) Silica-containing reinforcing agent: glass fiber having an average diameter of 10 μm and an average length of 3 mm (B-1) Glass fiber 1: Contains 55% by weight of silica (B-2) Glass fiber 2: Contains 48% silica by weight (C) Aluminum salt of diethylphosphinic acid (D) Melamine polyphosphate (E) Melamine cyanurate (F) Aromatic phosphate: Product name PX200 (G) Heat-resistant additive: Product name B-225 (H) Processability improver: Drop point: 110°C, melting point (mp): 104°C, density (23°C): 0.97g / cm 3 and the absolute viscosity (120°C) is 410mm 2 / s polyethylene (I) Anti-drop agent: Teflon (product name JF-4A)

[0115] <Examples 1 to 3 and Comparative Examples 1 to 6> The components were mixed in the amounts shown in Table 1 below. The physical properties of the prepared compositions were measured as follows and are shown in Table 1 below.

[0116] *Flow index (g / 10min): Measured in accordance with ISO 1133.

[0117] The mixture was then fed at 50 kg / hr and extruded at a screw speed of 250 rpm using a twin-screw extruder with a screw diameter of 45 mm at a temperature of 250°C, and the extrudate was then pelletized.

[0118] The prepared pellets were dried at 100°C for 4 hours or more and then extruded at 80°C to prepare test specimens measuring 2.5mm x 50mm x 90mm. The physical properties of the prepared test specimens were measured as follows and are shown in Table 1 below.

[0119] *Tensile strength (Mpa): Measured in accordance with ISO 527.

[0120] * Flame retardancy (Burning time / 5ea): 0.8mm test pieces were prepared and the total time (sec) required for five test pieces to burn was measured in accordance with UL 94. If the test piece achieved a V-0 rating, it was marked as OK, and the required time was also recorded. If the test piece did not achieve a V-0 rating, it was marked as NG.

[0121] *When the tensile strength value is a and the flow index value is b, the calculated value of a / b is shown in Table 1 below.

[0122] [Table 1]

[0123] As can be seen from Table 1, Examples 1 to 3, which incorporate all of the components of the present invention, have a flow index of 4 to 18 g / 10 min, a tensile strength of 135 to 160 MPa, a flame retardancy of V-0, and a total time required for combustion of 13.9 to 34 seconds, confirming a good balance of physical properties among rigidity, processability, and flame retardancy. The calculated a / b value was 7.77 to 40, which was confirmed to be within the appropriate range.

[0124] On the other hand, in Comparative Example 1, where aromatic phosphate and Teflon were used together, it was confirmed that the tensile strength and flow index were reduced, and the calculated value of a / b was also less than 7.76.

[0125] It was confirmed that the tensile strength was poor, the flow index could not be measured, and the calculated value of a / b could not be calculated.

[0126] In addition, in the case of Comparative Example 2 in which only aluminum salt of diethylphosphinic acid was added without adding melamine polyphosphate and melamine cyanurate, it was confirmed that the tensile strength and flow index were reduced.

[0127] In addition, in the case of Comparative Example 3, in which the content of aluminum salt of diethylphosphinic acid was reduced in the composition of Example 1 and polybutylene terephthalate was added to compensate for this, the tensile strength and flow index were excellent, but the flame retardancy was not measurable.

[0128] In addition, in Comparative Example 4, in which a reinforcing agent with a silica content below the appropriate range was used instead of the composition of Example 2, the flame retardancy was excellent, but the tensile strength and flow index were poor. In this case, the calculated value of a / b was also found to be less than 7.76.

[0129] In addition, in Comparative Example 5, where the amount of the reinforcing agent was reduced in the composition of Example 2 and polybutylene terephthalate was added to compensate for this, the flow index was excellent, but the tensile strength and flame retardancy were poor. In this case, the calculated value of a / b was also less than 7.76.

[0130] In addition, it was confirmed that the flame retardancy was poor in Comparative Example 6, in which the content of aluminum salt of diethylphosphinic acid and the content of melamine cyanurate were changed in the composition of Example 2. In this case, the calculated value of a / b was also less than 7.76.

[0131] In conclusion, it has been confirmed that the polybutylene terephthalate disclosed in the present invention is reinforced with a silica-containing reinforcing agent and contains flame-retardant and heat-resistant components of specific compositions, thereby achieving a balance of physical properties between processability, specific gravity, rigidity, and flame retardancy, making it suitable for use in the field of automotive parts as an alternative material to polyester resin composite materials containing halogen-based flame retardants.

Claims

1. 1. A polybutylene terephthalate resin composition comprising polybutylene terephthalate, an aluminum salt of diethylphosphinic acid, melamine polyphosphate, a silica-containing reinforcing agent, and a processability improver, The silica-containing reinforcing agent contains glass fibers containing 50% or more by weight of silica in the reinforcing agent, The processability improver has a drop point of 100 to 120°C, a melting point (mp) of 95 to 115°C, and a density (23°C) of 0.9 to 1.0 g / cm 3 and the absolute viscosity (120°C) is 350 to 450 mm 2 / s polyethylene, the melamine polyphosphate is contained in an amount of 1 to 5% by weight based on 100% by weight of the total of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent; The polybutylene terephthalate resin composition satisfies the following mathematical formula 1: Polybutylene terephthalate resin composition. [Formula 1] 7.76≦a / b≦45 (In the above formula 1, a is the tensile strength (MPa) of the polybutylene terephthalate resin composition measured in accordance with ISO 527, and a is in the range of 140 to 160; b is the flow index (g / 10 min) of the polybutylene terephthalate resin composition measured in accordance with ISO 1133 at 265°C under a load of 2.16 kg, and b is in the range of 4 to 20.

2. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the polybutylene terephthalate content is c and the silica-containing reinforcing agent content is d, and the polybutylene terephthalate resin composition satisfies the correlation of 0.5d≦c≦2d.

3. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the polybutylene terephthalate is contained in an amount of 15 to 65% by weight, based on a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent; or the polybutylene terephthalate resin composition comprises a processability improver and a heat resistance additive, the polybutylene terephthalate is contained in an amount of 15 to 65% by weight, based on a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, the processability improver, and the heat resistance additive, the processability improver is polyethylene wax, and the heat resistance additive is an antioxidant.

4. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the polybutylene terephthalate has an intrinsic viscosity (η) of 0.5 to 1.25 dl / g as measured in accordance with ASTM D2857.

5. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the silica-containing reinforcing agent is contained in an amount ranging from 10 to 50% by weight, based on a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent; or the polybutylene terephthalate resin composition comprises a processability improver and a heat resistance additive, and the silica-containing reinforcing agent is contained in an amount ranging from 10 to 50% by weight, based on a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, the processability improver, and the heat resistance additive, the processability improver being polyethylene wax, and the heat resistance additive being an antioxidant.

6. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the aluminum salt of diethylphosphinic acid is contained in an amount ranging from 5 to 35% by weight, relative to 100% by weight of the total of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, melamine polyphosphate, and the silica-containing reinforcing agent; or wherein the polybutylene terephthalate resin composition comprises a processability improver and a heat resistance additive, and the aluminum salt of diethylphosphinic acid is contained in an amount ranging from 5 to 35% by weight, relative to 100% by weight of the total of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, melamine polyphosphate, the silica-containing reinforcing agent, the processability improver, and the heat resistance additive, the processability improver being polyethylene wax, and the heat resistance additive being an antioxidant.

7. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the resin composition contains melamine cyanurate in an amount of 0.1 to 10% by weight, relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, and the melamine cyanurate; or the polybutylene terephthalate resin composition contains a processability improver and a heat resistance additive in an amount of 0.1 to 10% by weight, relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, the melamine cyanurate, the processability improver, and the heat resistance additive, wherein the processability improver is polyethylene wax and the heat resistance additive is an antioxidant.

8. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the resin composition contains a processability improver, the processability improver being contained in an amount of 0.001 to 3% by weight relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, and the processability improver, and the processability improver is polyethylene wax.

9. 2. The polybutylene terephthalate resin composition according to claim 1, wherein the resin composition further comprises a heat-resistant additive, the heat-resistant additive being contained in an amount of 0.001 to 3% by weight relative to a total of 100% by weight of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, the silica-containing reinforcing agent, and the heat-resistant additive, and the heat-resistant additive is an antioxidant.

10. 1. A method for producing a polybutylene terephthalate resin composition, comprising the steps of kneading and extruding polybutylene terephthalate, an aluminum salt of diethylphosphinic acid, melamine polyphosphate, a silica-containing reinforcing agent, and a processability improver, wherein the polybutylene terephthalate resin composition satisfies the following mathematical formula 1: The silica-containing reinforcing agent contains glass fibers containing 50% or more by weight of silica in the reinforcing agent, The processability improver has a drop point of 100 to 120°C, a melting point (mp) of 95 to 115°C, and a density (23°C) of 0.9 to 1.0 g / cm 3 and the absolute viscosity (120°C) is 350 to 450 mm 2 / s polyethylene, The melamine polyphosphate is contained in an amount of 1 to 5% by weight based on 100% by weight of the total of the polybutylene terephthalate, the aluminum salt of diethylphosphinic acid, the melamine polyphosphate, and the silica-containing reinforcing agent. A method for producing a polybutylene terephthalate resin composition. [Formula 1] 7.76≦a / b≦45 (In the above formula 1, a is the tensile strength (MPa) of the polybutylene terephthalate resin composition measured in accordance with ISO 527, and a is in the range of 140 to 160; b is the flow index (g / 10 min) of the polybutylene terephthalate resin composition measured in accordance with ISO 1133 at 265°C under a load of 2.16 kg, and b is in the range of 4 to 20.

11. A molded article comprising the polybutylene terephthalate resin composition according to any one of claims 1 to 9.

12. The molded product according to claim 11, wherein the molded product is an automotive electrical component.

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