KR20030037354A - Thermoplastic resin composition and the extrusion sheet with improved thermal resistance and flexural rigidity - Google Patents

Abstract

PURPOSE: Provided are a thermoplastic resin composition having excellent chemical resistance, cold impact strength, heat resistance and flexure strength, as well as surface smoothness, adhesiveness, and coating properties, and an extruded sheet. CONSTITUTION: The thermoplastic resin composition comprises (a) 40-70 wt% of poly(1,4-butylene terephthalate) resin, (b) 30-60 wt% of polycarbonate resin, (c) 5-20 parts by weight of core-shell copolymer having diene rubber as core structure, (d) 1-5 parts by weight of mica, and (e) 1-3 parts by weight of flowing agent(the parts by weight is based on the 100 parts by weight of base resin consisting of (a) and (b)). The poly(1,4-butylene terephthalate) resin(a) has weight average molecular weight of 50,000-130,000.

Description

Thermoplastic resin composition and the extrusion sheet with improved thermal resistance and flexural rigidity

The present invention relates to a thermoplastic resin composition for sheet extrusion, and more particularly to a poly (1,4-butylene terephthalate) resin and a polycarbonate resin having a specific molecular weight, and a diene rubber as an impact modifier. The thermoplastic resin composition for sheet extrusion containing a core-shell copolymer, mica, and a glidant having a core structure in a specific content may replace a sheet using an aluminum alloy or a fiber-reinforced plastic.

Poly (1,4-butylene terephthalate) (hereinafter referred to as 'PBT'), a thermoplastic resin, has excellent chemical resistance, mechanical properties, and electrical properties. It is widely used in various fields such as electrical, electronic and electronic parts. However, its use has been limited to applications having a low impact strength below the glass transition temperature (Tg) and requiring impact resistance.

On the other hand, polycarbonate (hereinafter referred to as 'PC') resin has a high impact resistance, but the chemical resistance is weak and its use is also limited.

Therefore, much research has been carried out to complement the advantages and disadvantages of the two resins.

U.S. Patent No. 3,864,428 discloses 25 to 85% by weight of polyester resin, 10 to 75% by weight of polycarbonate resin, and 2 to 35% by weight of copolymer copolymerized with vinyl monomers on the core structure of butadiene-based rubber as an impact modifier. The configured resin composition is disclosed. The resin composition has improved both chemical resistance and impact resistance by using a core-shell copolymer as an impact modifier, but is poor in weatherability and thermal stability due to the influence of unsaturated groups contained in butadiene-based core-shell polymers. In applications where heat resistance is required, there is a disadvantage in that the use thereof is restricted.

US Pat. No. 4,257,937 discloses a polyester-based thermoplastic resin composition having improved impact resistance, rigidity and heat resistance by using a polyacrylate resin and a polycarbonate resin as an impact modifier. In addition, US Patent No. 4,264,487 discloses a thermoplastic resin composition composed of 25 to 95% by weight of polyester resin, 1 to 50% by weight of polycarbonate resin, and an impact modifier having an acrylate rubber as a core structure. The resin composition has excellent thermal stability and long-term heat resistance as compared with the thermoplastic resin composition using an impact modifier having a butadiene rubber as a core structure, but the glass transition temperature of the acrylate rubber is higher than that of the diene rubber, and thus the impact resistance at low temperatures. It was very weak compared with the thermoplastic resin composition using the impact modifier which has this diene rubber as a core structure.

U.S. Patent 5,420,199 discloses a composition consisting of 50 to 90% by weight of polybutylene terephthalate resin, 5 to 40% by weight of polyolefin resin and 5 to 40% by weight of polycarbonate resin. The resin composition has excellent strength, rigidity, and dimensional stability, but lacks heat resistance and flexural rigidity, and has a disadvantage in that adhesiveness and paintability are reduced due to polyolefin resin.

Accordingly, the present inventors have studied to develop a new thermoplastic resin composition which is improved in the above-mentioned disadvantages, and as a result, the poly (1,4-butylene terephthalate) resin and polycarbonate resin as a base resin, A core-shell copolymer having a diene rubber as a core structure was used, and a thermoplastic resin composition was prepared by containing an appropriate amount of a mica and a fluidizing agent, and the prepared resin composition was excellent in heat resistance and flexural rigidity. When the polyurethane-based adhesive is used, it can be applied to a panel, and the adhesive is well adhered to a polystyrene foam, a polyurethane foam, a veneer plate, and the like. Was completed.

Therefore, the object of the present invention is not only excellent in chemical resistance, low temperature impact resistance, heat resistance and bending rigidity that can replace the aluminum alloy or fiber-reinforced plastic sheet used as the outer panel of the conventional box storage box, the surface smoothness, adhesiveness It is to provide a thermoplastic resin composition for sheet extrusion excellent in paintability.

Specifically, an object of the present invention includes a core-shell copolymer, a mica and a fluidizing agent having a diene rubber as a core structure based on a poly (1,4-butylene terephthalate) resin and a polycarbonate resin. It is to provide a thermoplastic resin composition for sheet extrusion.

In order to achieve the above object, the present invention provides a sheet comprising a core-shell copolymer, a mica and a fluidizing agent having a poly (1,4-butylene terephthalate) resin, a polycarbonate resin, and a diene rubber as a core structure. Provided is a thermoplastic resin composition for extrusion.

Hereinafter, the present invention will be described in more detail.

The thermoplastic resin composition of the present invention,

(A) 40 to 70% by weight of a poly (1,4-butylene terephthalate) resin,

(B) with respect to 100 parts by weight of the base resin consisting of 30 to 60% by weight of polycarbonate resin,

(C) 5 to 20 parts by weight of the core-shell copolymer having a diene rubber as a core structure,

(D) 1 to 5 parts by weight of a mica, and

(E) from 1 to 3 parts by weight of a fluidizing agent.

(A) poly (1,4-butylene terephthalate) (poly (1,4-butylene terephthalate), hereinafter referred to as 'PBT')

PBT has the property of absorbing up to 0.45% of water in water, resulting in high dimensional stability. In addition, it exhibits excellent environmental stress cracking and chemical resistance due to its excellent chemical-resistance semi-crystalline structure.

In general, the PBT may be prepared by condensation polymerization of terephthalic acid or dimethyl terephthalate with tetramethylene glycol. It is already well known to those of ordinary skill in this field. It is also already marketed by various companies under various brand names.

The PBT determines the appropriate molecular weight and its content in consideration of processability and physical properties obtained after processing. In the present invention, it is preferable to use a weight average molecular weight (Mw) of 50,000 to 130,000 through several experiments, and it is preferable to contain 40 to 70% by weight in the base resin also in the content. If the weight average molecular weight is less than 50,000, mechanical properties and heat resistance are lowered. If the weight average molecular weight is more than 130,000, there is a problem in processing of the resin due to an increase in melt viscosity. In addition, if the content is less than 40% by weight, the chemical resistance and fluidity of the produced thermoplastic resin is lowered, and if the content exceeds 70% by weight, impact resistance is lowered, which is not preferable.

(B) polycarbonate (hereinafter referred to as 'PC') resin

PC resin is excellent in impact resistance, heat resistance, weather resistance, self-extinguishing, flexibility, processability and transparency. It has excellent weather resistance and maintains high physical properties for a long period of time.

The method for producing a PC resin used in the present invention follows a conventional manufacturing method, and specifically, is prepared by reacting dihydroxy phenol and phosgen in the presence of a molecular weight regulator and a catalyst, or dihydroxyphenol. It can be prepared using the ester interchange reaction of the precursor obtained by (dihydroxy phenol) and diphenyl carbonate. In the embodiment of the present invention, a bisphenol A-based linear polycarbonate resin polymerized using bisphenol A and diphenyl ester was used.

It is preferable that the weight average molecular weights of polycarbonate resin are 21,000-38,000, and it is preferable to contain 30-60 weight% in base resin. If the weight average molecular weight is less than 21,000, mechanical properties and heat resistance are lowered. If the weight average molecular weight is more than 38,000, there is a problem in processing of the resin due to an increase in melt viscosity. In addition, when the content is less than 30% by weight, the impact resistance of the manufactured thermoplastic resin composition is lowered. When the content is more than 60% by weight, chemical resistance and fluidity are lowered, which is not preferable.

(C) a core-shell copolymer having a diene rubber as a core structure; Impact modifier

In the present invention, an impact modifier is added to increase the impact resistance of the thermoplastic resin.

The impact modifier is a core-shell copolymer having a diene rubber as a core structure, and after polymerizing at least one selected from a diene rubber having 4 to 6 carbon atoms, at least one monomer selected from a graftable vinyl monomer is used. It is made into a core-shell structure by grafting on rubber.

The core-shell copolymer of the present invention has a rubber component having excellent elasticity and impact resistance as a core, and includes a conventional vinyl polymer as a shell, so that the core-shell copolymer has excellent compatibility with base resins, and considering impact resistance and compatibility. To use a graft ratio of 20 to 90%.

The diene rubber used in the core-shell copolymer is one selected from the group consisting of butadiene, isoprene, isoprene, chloroprene, pentadiene and hexadiene. In addition, the vinyl monomer includes an intramolecular double bond and is not particularly limited in the present invention. For example, the vinyl monomers include vinyl chloride, vinyl fluoride, vinylidene fluoride, trichlorofluoroethylene, styrene, α-methylstyrene, methyl methacrylate, vinyl ester, acrylic acid, methacrylic acid, N Vinylpyrrolidone, acrylonitrile, acrylamide and the like.

The core-shell copolymer is determined in order to maintain the impact resistance of the thermoplastic resin according to the present invention to a predetermined level or more, and contains 5 to 20 parts by weight based on 100 parts by weight of the base resin. If the content is less than 5 parts by weight, the low temperature impact resistance is lowered, and if it exceeds 20 parts by weight, the mechanical properties and fluidity is lowered.

According to the embodiment of the present invention, it was found that the core-shell copolymer has a great influence on the impact strength, in particular, the impact strength at low temperatures.

(D) Mica

In the present invention, mica is added to improve heat resistance, flexural rigidity and dimensional stability. The mica is composed of 40 to 42% of silicon oxide, 20 to 24% of magnesium oxide, 9 to 10% of aluminum oxide, 9 to 11% of iron oxide, and 10 to 11% of potassium oxide, and has a particle size of 4 to 70 μm, It has a flaky structure with a thickness of 1.1 to 2.6 mu m.

In the present invention, the mica preferably contains 1 to 5 parts by weight based on 100 parts by weight of the base resin. If the content is less than 1 part by weight, the heat resistance and the flexural rigidity are lowered, so that the warpage of the panel assembled when used as the outer panel of the top of the loading box is severe. If the content is more than 5 parts by weight, the impact resistance is reduced and the surface smoothness is reduced.

(E) glidant

In the present invention, a fluidizing agent is added to increase the conformalal mobility of the resin during processing to facilitate processing. The fluidizing agent forms a lubricating film between the polymer particles to reduce the mutual adhesion between the components, showing improved flow characteristics. This increases the flowability, increases the strength and serves to improve the quality of the obtained product.

Titanium dioxide is used in the present invention as the fluidizing agent. The titanium dioxide is preferably used having a rutile type crystal structure having an average particle size of 0.15 to 0.25 ㎛. If the particle size is larger than the above range, the finished product acts as a crack occurrence point due to external impact, so that the defective rate of the product is high. do.

In the present invention, the fluidizing agent preferably contains 1 to 3 parts by weight based on 100 parts by weight of the base resin in consideration of fluidity and impact resistance during processing. If the content is less than 1 part by weight, it may not have fluidization characteristics. If the content is more than 3 parts by weight, titanium dioxide may act as a photocatalyst upon exposure to ultraviolet rays, resulting in decomposition of poly (1,4-butylene terephthalate) and polycarbonate resin. The impact resistance is lowered, which is undesirable.

As described above, the thermoplastic resin composition of the present invention contains PBT, PC, impact modifier, mica and fluidizing agent in a certain amount, and exhibits excellent heat resistance, flexural rigidity, impact strength and chemical resistance, and sheet workability. According to the embodiment of the present invention, the thermoplastic resin composition not only maintains the excellent impact resistance of the PC, it can be seen that the excellent chemical resistance of the PBT to maintain the advantages of each other intact and complement the disadvantages.

In addition, the thermoplastic resin composition of the present invention may further include an additive for various purposes, the type and content thereof according to those skilled in the art. For example, reinforcing and nucleating agents to improve mechanical properties, lubricants and anti-separation agents to improve surface properties, flame retardants to improve chemical properties, UV stabilizers and antioxidants, dyes to improve aesthetic properties, deodorants and deodorants And it may further include a flow regulator, a heat stabilizer and an accelerator for improving the processing properties.

In addition, the manufacturing method of the thermoplastic resin composition of the present invention is compression molding, extrusion molding, injection molding, blow molding and vacuum molding by a commonly used polymer blending method. (vaccum molding) method and the like can be used, and extrusion molding is carried out when manufacturing for sheets.

For example, PBT, PC, impact modifier, fluidizing agent is injected into a hopper, dried, injected into a twin screw extruder, and extruded into pellets.

The sheet produced by sheet molding using the thermoplastic resin composition of the present invention not only maintains the excellent impact resistance of the PC resin, but also has the chemical resistance of the PBT resin, and can be usefully used for automobiles and various electric and electronic parts.

The thermoplastic resin composition according to the present invention can be used as an outer panel of the top loading box box because it is excellent in workability and can form a sheet having a wide width of 2 to 2.5 m, as well as excellent in heat resistance and bending rigidity.

The outer panel of the existing tower box is made of aluminum alloy or fiber reinforced plastic. In the outer panel of the box, the outer panel is made of aluminum alloy or fiber-reinforced plastic sheet as the outer layer, and the polystyrene foam or polyurethane foam is bonded to the inner layer for shock absorption and insulation, or the panel's strength and rigidity are reinforced. To this end, reinforcing plates such as veneers have been inserted and bonded between the outer layer and the inner layer.

On the other hand, the outer panel may be manufactured by bonding the styrene foam or urethane foam to the extruded sheet prepared by the composition of the present invention. In order to further increase the strength of the outer panel, it is inserted between the extruded sheet and the foam to bond the sheet reinforcement. The sheet reinforcing agent is used that is commonly used in this field, for example, selected from the group consisting of veneers, polyethylene, polypropylene and polyester. The outer panel manufactured by the above method has a low thermal conductivity, thereby reducing heat loss, and has an advantage of excellent condition and no scratches during low-speed collision of the thrown material. In particular, it can be molded into a single sheet width-size sheet, easy processing, and there is no seam on the surface and there is an excellent smoothness because there is no fiber.

EMBODIMENT OF THE INVENTION Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to an Example.

Examples 1 to 5 and Comparative Examples 1 to 6

To prepare a thermoplastic resin composition for sheet extrusion in the composition and content shown in Table 1.

PBT, PC, core-shell copolymer, mica, and glidant were injected into the hopper, and then kneaded and extruded into a co-rotating twin screw extruder having a L / D of 40 and a barrel diameter of 19 mm to pellet-type thermoplastic resin. The composition was prepared.

At this time, the barrel temperature was set at 200 ° C. to 265 ° C. for each section, and the die temperature was set to 270 ° C.

PBT ¹⁾ (wt%) PC ²⁾ (wt%) Core-shell copolymer ³⁾ (parts by weight) Mica ⁴⁾ (parts by weight) Glidant ⁵⁾ (parts by weight) Example 1 60 40 15 4 2 Example 2 60 40 15 One 2 Example 3 60 40 7 3 One Example 4 40 60 15 3 2 Example 5 70 30 15 3 2.5 Comparative Example 1 10 90 15 3 2 Comparative Example 2 90 10 15 3 2 Comparative Example 3 60 40 15 3 0 Comparative Example 4 60 40 30 3 5 Comparative Example 5 60 40 15 10 2 Comparative Example 6 60 40 15 0 2

Each component used in the said Example and the comparative example is as follows.

1) Poly (1,4-butylene terephthalate) resin: It has a weight average molecular weight of 90,000 and is a tribit 1700S of Samyang Corporation.

2) Polycarbonate Resin: A triex 3030 from Samyang Corporation with a weight average molecular weight of 29,000 bisphenol A.

3) Core-Shell Copolymer: A core-shell copolymer having a diene rubber as a core structure as an impact modifier and having a methyl methacrylate monomer grafted to butadiene rubber. EXL-2602.

4) Mika: CLARITE MICA 400W from KURARE, Japan.

5) Fluidizing agent: Rutile titanium dioxide was used, and a particle size of 0.15∼0.25 μm was used.

Experimental Example 1

In order to examine the physical properties of the pellet-type thermoplastic resin composition prepared in Examples 1 to 5 and Comparative Examples 1 to 6 were carried out as follows.

Each pellet prepared above was hot-dried at 100 ° C. for 5 hours, and then tensile, flexural and impact specimens were prepared by injection molding. At this time, the nozzle temperature was 255-325 degreeC and the metal mold temperature was 60 degreeC according to the composition of resin. Physical properties of the prepared specimens were performed according to the following results, and the obtained results are shown in Table 2 below.

1) Heat distortion temperature (℃): It was evaluated according to ASTM D-648 at a load of 18.6 kgf / cm2.

2) Flexural modulus (kgf / cm2): evaluated according to ASTM D-790.

3) Tensile Strength (MPa): evaluated according to ASTM D-638.

4) Chemical resistance (%): The tensile specimens were immersed in T-725 thinner for 24 hours, then taken out and naturally dried in air for 1 week, and then the tensile strength retention was measured. The solvent used for chemical resistance evaluation used T-725 thinner of Dae Chemical Co., Ltd. which is an acrylic / urethane paint thinner mainly used for painting PC / PBT blend resin. The main components and content of the thinner are 10 to 20% of toluene, 20 to 30% of butyl acetate, 5 to 10% of cellosolve acetate, and 15 to 20% of xylene.

5) Impact resistance (J / mm): Circular specimen with a thickness of 1.5 mm and a diameter of 10 cm, the weight of the weight is 12.15 kg and the speed of the weight in accordance with ASTM D-3763 at room temperature (25 ℃) and low temperature (-20 ℃). 200 m / min, the diameter of the tub (tup) was dropped to 12.75 mm diameter was measured by dividing the energy consumed when breaking by the thickness.

Experimental Example 2

Sheet molding was performed using the thermoplastic resin composition consisting of the compositions of Examples 1 to 5 and Comparative Examples 1 to 6 to prepare a width / thickness of 2,300 mm / 1.1 to 1.3 mm. Sheet molding was performed using a sheet extruder with a cylinder diameter of 120 mm manufactured by Breyer, Germany. Evaluation of the prepared sheet was performed by the following, the results obtained are shown in Table 2 below.

1) Surface smoothness: evaluated by visual observation.

2) Adhesiveness: After bonding the styrene foam and the veneer plate to the extruded sheet using urethane adhesive of Dongbu Fine Chemical Co., Ltd., the adhesive strength and the adhesive state were evaluated.

3) Paintability: An acrylic / urethane paint of Daehan B Chemical Co., Ltd. was applied to the extruded sheet to evaluate the coating state by visual observation.

4) Sheet workability: evaluated by the uniformity of the molded sheet thickness.

Heat Deflection Temperature (℃) Flexural Rigidity (kgf / ㎠) Chemical resistance (%) Impact resistance (J / mm) Surface smoothness Adhesive Paintability Sheet Machinability Room temperature (25 ℃) Low temperature (-20 ℃) Example 1 94 22,800 93 18.4 17.7 ◎ ◎ ◎ ◎ Example 2 86 20,100 94 19.6 19.2 ◎ ◎ ◎ ◎ Example 3 95 22,100 95 17.6 17.0 ◎ ◎ ◎ ◎ Example 4 100 23,200 86 20.1 19.4 ◎ ◎ ◎ ◎ Example 5 89 22,700 97 16.6 15.7 ◎ ◎ ◎ ◎ Comparative Example 1 109 23,100 64 22.5 22.0 △ ◎ ◎ △ Comparative Example 2 81 20,600 99 13.9 12.8 △ △ △ △ Comparative Example 3 95 21,000 93 16.5 15.0 △ ◎ ◎ △ Comparative Example 4 84 20,900 92 19.8 19.2 - - - Ｘ Comparative Example 5 106 24,000 92 13.8 12.5 Ｘ ◎ ◎ △ Comparative Example 6 83 18,500 94 21.2 20.7 ◎ ◎ ◎ ◎

◎: Excellent, △: Normal, X: Poor,-: No measurement

According to Table 2, the physical properties of the embodiment according to the present invention was found to be superior to that of the comparative example. Specifically, the heat deflection temperature, bending stiffness, chemical resistance, and impact resistance of Examples 1 to 5 showed higher values than those of Comparative Examples 1 to 6. In Comparative Example 1, the chemical resistance was deteriorated due to the lack of PBT content and excessive PC content, and in Comparative Example 2, the chemical resistance was good due to the excessive content of PBT and lack of PC content, but the impact resistance was decreased. Comparative Example 3, which does not include a glidant, has low impact resistance and lacks fluidity, resulting in lowered surface smoothness and sheet formability. Comparative Example 4 using an excessive amount of the core-shell copolymer was good in flexural stiffness and chemical resistance, but could not be manufactured into a sheet.

In addition, the composition of Example 1 was excellent in heat deformation temperature, flexural rigidity and chemical resistance when compared to Example 1 containing mica and Comparative Example 6 not containing. In Comparative Example 5 containing an excessive amount of mica, physical properties such as heat deformation temperature and bending stiffness were good as compared with Example 1, but the surface smoothness was poor when the sheet was manufactured.

Particularly, in Comparative Examples 1, 3, and 4, the extruder was overloaded due to the high melt viscosity of the resin at the normal processing temperature, and a decrease in mechanical strength due to thermal decomposition of the resin occurred when the processing temperature was increased to lower the melt viscosity. .

In addition, when the sheet made of the resin composition of the present invention is used as a panel of the top car, the specific gravity is 1.26, lighter than the specific gravity of the aluminum alloy 2.7, and the thermal conductivity is 0.19 W / m ℃, and the thermal conductivity of the aluminum alloy is 210 W / m ℃. Compared with the small size, especially in the refrigeration tower, there is an advantage of lowering the heat loss. In addition, it has the advantage of easy processing method, excellent surface condition and no scratches at low speed impact of the thrown object. In addition, it is lighter than fiber-reinforced plastics and is easier to process, so it is possible to form a long-width sheet having a top car size into one sheet, and there is no seam on the surface and excellent smoothness because no fiber is used.

Therefore, according to the present invention, a thermoplastic resin composition for sheet extrusion comprising a poly- (1,4-butylene terephthalate) resin, a polycarbonate resin, a core-shell copolymer having a diene rubber as a core structure, a mica, and a fluidizing agent Was prepared. The prepared thermoplastic resin composition is not only excellent in heat resistance, bending stiffness, chemical resistance and impact strength, but also excellent in surface smoothness, adhesiveness, and paintability, so that a long width extruded sheet can be continuously formed. Can be used as In addition to maintaining the excellent impact resistance of polycarbonate, as well as having a chemical resistance of poly (1,4-butylene terephthalate) it can be usefully used for automobiles and various electrical and electronic components.

Claims (8)

(A) 40 to 70% by weight of a poly (1,4-butylene terephthalate) resin, (B) with respect to 100 parts by weight of the base resin consisting of 30 to 60% by weight of polycarbonate resin, (C) 5 to 20 parts by weight of the core-shell copolymer having a diene rubber as a core structure, (D) 1 to 5 parts by weight of a mica, and (E) A thermoplastic resin composition for sheet extrusion, comprising 1 to 3 parts by weight of a fluidizing agent. The thermoplastic resin composition for sheet extrusion according to claim 1, wherein the (A) poly (1,4-butylene terephthalate) resin has a weight average molecular weight of 50,000 to 130,000. The thermoplastic resin composition for sheet extrusion according to claim 1, wherein the polycarbonate resin (B) is a bisphenol A linear polycarbonate resin, and has a weight average molecular weight of 21,000 to 38,000. The thermoplastic resin for sheet extrusion according to claim 1, wherein the core-shell copolymer is obtained by polymerizing at least one selected from among diene monomers having 4 to 6 carbon atoms, and then grafting a conventional vinyl monomer rubber. Composition. The thermoplastic resin composition for sheet extrusion according to claim 4, wherein the graft ratio of the core-shell copolymer is 20 to 90. The thermoplastic sheet for extrusion according to claim 4, wherein the diene monomer is selected from the group consisting of butadiene, isoprene, chloroprene, pentadiene and hexadiene. Resin composition. The thermoplastic resin composition of claim 1, wherein the fluidizing agent is titanium dioxide and has a particle size of 0.15 to 0.30 μm. An extruded sheet obtained from the thermoplastic resin composition for sheet extrusion according to claim 1.