KR101405869B1 - Method for Preparing Polyester/Polycarbonate Blend with Advanced Color Stability - Google Patents

Abstract

A process for producing a polyester / polycarbonate blend having excellent color stability is disclosed. The method for producing the polyester / polycarbonate blend includes the steps of: (a) compounding polyethylene terephthalate (PET) and polycarbonate (PC) to obtain a PET / PC blend; And (b) compounding the resultant PET / PC blend with a large amount of cyclohexane dimethanol (CHDM) glycol-modified PET, wherein the content of PC in the PET / PC blend is 10 to 70 wt% The content of CHDM glycol-modified PET is 0.2 to 2.5 times by weight with respect to PC, and the mass of CHDM glycol-modified PET is 30 to 80% by mole of CHDM with respect to the diol component, and the mass of CHDM glycol- The content is 20 to 70 mol% with respect to the diol component.

PET, PC, PCTG, heat distortion temperature, transparent polyester, heat resistance

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for producing a polyester / polycarbonate blend having excellent color stability,

The present invention relates to a process for producing a polyester / polycarbonate blend having excellent color stability, and more particularly to a process for producing a polyester / polycarbonate blend capable of improving heat resistance and color stability as compared with a conventional polyester / polycarbonate blend ≪ / RTI >

Since polyester is excellent in mechanical strength, heat resistance, transparency and gas barrier properties, it is most suitable as a container for beverage filling such as juice, soft drink and carbonated beverage, packaging film, audio and video film, . Also, it is widely used as industrial materials such as medical fibers and tire cords in the world. BACKGROUND OF THE INVENTION [0002] Polyester sheets and sheets are widely used for materials such as cases, boxes, partitions, store shelves, protective panels, blister packaging, building materials, and interior and exterior materials with good transparency and excellent mechanical strength. As an application of a new polyester which has recently attracted attention, an example in which a thick plastic sheet is molded and used as a building interior material, a molded signboard, and the like is increasing. However, polyester has a lower heat distortion temperature (HDT) than other materials used in sheet applications, such as acrylic (PMMA) and polycarbonate (PC) May be unsuitable for use as a < / RTI > Therefore, there have been various technical attempts to improve the heat resistance of the polyester. Among them, a blending technique with PC is a representative method.

However, because PET and PC have different melt viscosity and molecular structure, it is difficult to improve heat resistance by simply blending them. PET, which is a typical crystalline polymer, increases the mechanical strength in the blend by its crystal structure and imparts toughness to the entire polymer backbone. Among the crystalline PET, the homopolyester has a relatively high crystallization rate as compared with the copolyester, and thus exhibits a high heat distortion temperature (HDT). In the blend matrix, the PET is distributed in the domains of tens to hundreds of nano levels, . At this time, reducing the size of the domain and increasing the distribution improves the transparency as well as the heat resistance of the blend, and the heat resistance is more influenced by the distribution of the domains.

 Techniques for using copolymers or various complex catalysts to solve the heat resistance problem of PET / PC blends are known. U.S. Patent No. 3,864,428 discloses a technique relating to the blend composition of polyester and PC. In U.S. Patent No. 4,879,355, a copolymer of PET and bisphenol-A is prepared and introduced into a blend of PET and PC to provide transparency and heat resistance And the like. Also, as disclosed in U.S. Patent No. 5,942,585, techniques for blending a PC with a large amount of CHDM glycol-modified polyester have recently been disclosed. On the other hand, US Pat. No. 6,723,768 B2, concerning the color stability of polyester / PC blend, confirmed that the color stability of the blend was improved when the titanium content was within 30 ppm, and the yellowing problem of the blend was attributed to the titanium content And that they are closely related.

Accordingly, an object of the present invention is to provide a process for producing a polyester / polycarbonate blend capable of improving heat resistance (HDT) and color stability while maintaining excellent moldability.

It is a further object of the present invention to provide a process for producing a polyester / polycarbonate blend having excellent color stability by blending three or more blend components in a particular sequence and method.

In order to achieve the above object, the present invention provides a method for producing a PET / PC blend, comprising: (a) obtaining a PET / PC blend by compounding polyethylene terephthalate (PET) and polycarbonate (PC); (Hereinafter referred to as " a large amount of cyclohexane dimethanol (CHDM) glycol-denatured PET " or " CHDM-modified PET ", as occasion demands), and (b) a PET / PC blend obtained by reacting cyclohexanedimethanol glycol-modified polyethylene terephthalate Wherein the content of PC in the PET / PC blend is from 10 to 70 wt%, the content of CHDM glycol-modified PET is from 0.2 to 2.5 times by weight with respect to PC, and the amount of CHDM glycol- PET is a PET in which CHDM is 30 to 80 mol% copolymerized with respect to the diol component, and the content of ethylene glycol in the mass CHDM glycol-modified PET is 20 to 70 mol% based on the diol component. And a manufacturing method thereof. Here, the PET is PET composed of terephthalic acid, ethylene glycol and / or alkylene glycol having 3 to 6 carbon atoms, or isophthalic acid, CHDM or diethylene glycol may be added to the PET component in an acid or diol component 1 to 10 mol% copolymerized with PET.

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

Generally, blending of polyester and polycarbonate decreases heat resistance, and heat resistance tends not to be proportional to blend composition ratio. In the present invention, the blend of polyester and polycarbonate has an optimum composition that can overcome the phenomenon that heat resistance is not proportional to the blend composition.

In general, PCs do not contain metal components. In the case of PET, an antimony-based organometallic component is used as a catalyst, while in the case of some PET or PCTG (glycol-modified poly (1,4-cyclohexylenedimethylene terephthalate) A titanium-based organometallic component is used as a catalyst for the polymerization reaction. In the present invention, PET and PC without titanium component are blended first, and then the blend thus obtained is blended with PCTG containing titanium component , A polyester / polycarbonate blend having better color stability can be obtained.

The blend of PCTG and PC has the heat resistance of PC and the ductility of PCTG, where PCTG is CHDM glycol-modified PET, a copolyester based on terephthalic acid, ethylene glycol and cyclohexanedimethanol (CHDM). As for the PCTG / PC blend, studies have been actively carried out since the 1980s to improve the compatibility between the two resins. PCTG / PC blends can exhibit complementary new properties depending on the composition of each component , And there is a side effect that the color stability is lowered by the interaction of each component at the same time. In particular, in the case of the PCTG / PC blend having a relatively long retention time, the yellowing of the blend is yellowish during the molding process. In the manufacturing method according to the present invention, the yellowing phenomenon can be minimized by first compounding PET and PC and then blending them with PCTG.

Specifically, the process for producing a polyester / polycarbonate blend according to the present invention comprises the steps of: (a) compounding PET and PC to obtain a PET / PC blend; And (b) compounding the resulting PET / PC blend with a large amount of CHDM glycol-modified PET.

As the PET component used as a main material in the present invention, PET composed of terephthalic acid, ethylene glycol and / or alkylene glycol having 3 to 6 carbon atoms may be used, or may be prepared by adding isophthalic acid, CHDM or diethylene PET in which a small amount of glycol is copolymerized can be used. When the isophthalic acid is copolymerized, the content thereof is 1 to 10 mol% based on the total amount of the acid component of the copolymerized PET, and when CHDM or diethylene glycol is copolymerized, the content thereof is the total diol component Based on the total weight of the composition.

The PC may use various general extrusion and injection polymers prepared by polymerization of bisphenol-A as a basic constituent. The PC content is 10 to 70% by weight, preferably 10 to 50% by weight, based on the PET / PC blend. When the content of PC is less than 10% by weight, the improvement of heat resistance is insignificant. When the content of PC is more than 70% by weight, the blend of PC to PET and economical efficiency are lowered.

The mass of CHDM glycol-modified PET (PCTG) added after the blending of the PET component and the PC component is used in a weight ratio of 0.2 to 2.5, preferably 0.5 to 2.0, to PC. If the amount of the large amount of CHDM glycol-modified PET is less than 0.2 times by weight with respect to PC, the effect of improving the transparency is insignificant. Even when the amount is more than 2.5 times, further improvement in transparency can not be expected, I can not. The mass of CHDM glycol-modified PET is composed of CHDM and ethylene glycol as diol components and terephthalic acid as an acid component. The content of CHDM is 30 to 80 mol% based on the total diol component of the mass CHDM glycol-modified PET, The content of ethylene glycol in the high CHDM glycol-modified PET is from 20 to 70 mol% based on the diol component. If the content of CHDM is less than 30 mol% or exceeds 80 mol%, the transparency of the blended product may be impaired.

The polyester-based polymer used in the present invention, that is, the PET and the high-mass CHDM glycol-modified PET is a product obtained by polymerizing using a compatibilized organic or inorganic catalyst such as antimony, cobalt, germanium, titanium, calcium or aluminum desirable.

When molding the polyester / polycarbonate blend of the present invention as described above, the molded transparent polyester has a haze value of 30% or less and a heat distortion temperature (HDT) of 75 ° C As a result, transparency and heat resistance are excellent at the same time.

The method for producing a polyester / polycarbonate blend according to the present invention can improve heat resistance and color stability by first compounding PET and PC and then further compounding the PET component modified with CHDM, Can be easily and economically applied to fields where the use thereof is limited due to the deterioration of color stability of the ink.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. The following examples are intended to further illustrate the present invention, and the scope of the present invention is not limited by these examples.

The PET used in the following examples and comparative examples was SKYPET BL grade produced by SK Chemicals (hereinafter component A, isophthalic acid is copolymerized with 2 to 3 mol% of the total acid with respect to the whole acid, and CHDM is 3 to 10 mol (CH3) content (%) was produced by SK Chemicals as a large amount CHDM modified polyester, and PC product produced by LGDOW (Melt Index (MI): 30, 50 to 80 mol%, based on the diol component, of component C) was used.

[Comparative Example 1]

Using a dehumidifying dryer, 5 kg of Component A dried for 5 hours at 160 ° C., 4 kg of Component B dried at 120 ° C. for 5 hours in the same dehumidifying dryer, and 1 kg of Component C dried for 5 hours at 70 ° C. using the same dehumidifying dryer Placed in a dehumidified container, tumbled for about 3 minutes, and sufficiently mixed. The mixed raw materials were compounded through an extruder (Haake Extruder) manufactured by Hasegawa at 270 DEG C and 50 rpm to prepare blend chips. Using the manufactured blend chip, a cold runner type water-cooled mold capable of producing a 12 mm x 120 mm specimen with a thickness of 3.0 mm and a width of 40 mm x 40 mm with the same thickness was injected. The injection machine used had an L / D of 23 and a compression ratio of 3, and the injection molded specimen was measured for transparency, color B (color value of transparency publication in transmission mode, using a Nippon Denshoku 300A permeability meter And a value of color B indicates that the degree of yellowness increases as the value of 0 is higher) and the heat distortion temperature (HDT) are measured, and the results are shown in Table 1 below.

[Comparative Examples 2 to 3]

As shown in the following Table 1, specimens were injected in the same manner as in Comparative Example 1, except that the amounts of Component A, Component B and Component C were varied, and the transparency, Color B and heat distortion temperature And the results are shown in Table 1 below.

[Example 1]

Using a dehumidifying dryer, 5 kg of the component A dried for 5 hours at 160 ° C. and 4 kg of the component B dried at 120 ° C. in the same dehumidifying dryer for 5 hours were placed in a sufficiently dehumidified container and sufficiently mixed by tumbling for about 3 minutes. The mixed raw materials were compounded through an extruder (Haake Extruder) at 270 DEG C and 50 rpm to obtain 9 kg of PC / PET blend. The resulting PC / PET blend and 1 kg of the component C dried for 5 hours at 70 DEG C in a dehumidifying dryer were placed in a sufficiently dehumidified container, tumbled for about 3 minutes, and sufficiently mixed. The prepared material was compounded using an extruder (Haake Extruder) at 270 DEG C and 50 rpm to prepare a blend chip. Using the blend chip manufactured, a cold runner-type water-cooled mold capable of producing a 12 mm x 120 mm specimen having a thickness of 3.0 mm and a thickness of 40 mm x 40 mm was injected. The injection machine used had a screw L / D of 23 and a compression ratio of 3. The transparency, color B and heat distortion temperature of the specimens were measured and the results are shown in Table 1 below.

[Examples 2 to 3]

As shown in the following Table 1, the specimens were blended by the same procedure and the same procedure as in Example 1 except that the amounts of the components A, B, and C were varied, and the transparency of the specimen, Color B And the heat distortion temperature were measured. The results are shown in Table 1 below.

Component A Component B Component C Haze (%) Color-b HDT (° C) Comparative Example 1 5kg 4kg 1kg 35 6.7 111 Comparative Example 2 5kg 3kg 2kg 7 4.2 98 Comparative Example 3 7kg 2kg 1kg 9 2.1 75 Example 1 5kg 4kg 1kg 29 5.9 114 Example 2 5kg 3kg 2kg 6 3.8 102 Example 3 7kg 2kg 1kg 7 1.9 79

In Table 1, when the PET and PC were compounded first according to the present invention, and then the copolyester material modified with CHDM was further compounded (Example), the materials of the three components were compounded at one time The color b value was remarkably improved and the high heat distortion temperature (HDT) was exhibited and the heat resistance was also excellently exhibited.

Claims (5)

(a) mixing polyethylene terephthalate (PET) and polycarbonate (PC) and compounding them using an extruder to obtain a PET / PC blend; And (b) mixing the obtained PET / PC blend with cyclohexane dimethanol glycol-modified polyethylene terephthalate (CHDM-modified PET) and compounding using an extruder, The content of PC in the PET / PC blend is 10 to 70% by weight, the content of CHDM-modified PET is 0.2 to 2.5 times by weight with respect to PC, and the CHDM- Wherein the content of ethylene glycol in the CHDM-modified PET is 20 to 70 mol% based on the diol component, and the content of ethylene glycol in the CHDM-modified PET is 20 to 70 mol% based on the diol component. The method of claim 1, wherein the PET is PET comprising terephthalic acid, ethylene glycol and / or an alkylene glycol having 3 to 6 carbon atoms, or an isophthalic acid, cyclohexanedimethanol (CHDM), or diethylene glycol When the isophthalic acid is copolymerized, the content thereof is 1 to 10 mol% based on the total amount of the acid component of the copolymerized PET. When CHDM or diethylene glycol is copolymerized, By weight based on the total diol component of the PET. The process for producing a polyester / polycarbonate blend according to claim 1, wherein the content of PC in the PET / PC blend is 10 to 50% by weight, and the content of the CHDM-modified PET is 0.5 to 2.0 times by weight with respect to PC . The polyester / polycarbonate blend of claim 1, wherein the PET and CHDM modified PET are polymerized using a polymerization catalyst selected from the group consisting of antimony, cobalt, germanium, titanium, calcium, and aluminum Gt; A polyester / polycarbonate blend obtained by molding the polyester / polycarbonate blend of claim 1 and having a haze of 30% or less and a heat distortion temperature (HDT) of 75 ° C or more on a 3 mm thick specimen.