KR20010073015A - Polyester- polycarbonate composition with improved hot-plate weldability - Google Patents

Abstract

The present invention is directed to the provision of a resin composition having improved hot plate weldability in which no carbonized resin remains on the hot plate and the fine filaments of the resin are not pulled out. According to the invention, (A) 98 to 1% by weight polyester resin, (B) 1 to 98% by weight polycarbonate resin, (C) 0.5 to 18% by weight core-shell copolymer and (D) 30,000 There is provided a resin composition containing 0.01 to 4% by weight of polytetrafluoroethylene (wherein the total amount of A to D is 100% by weight) having the above number average molecular weight.

Description

POLYESTER-POLYCARBONATE COMPOSITION WITH IMPROVED HOT-PLATE WELDABILITY}

The thermoplastic resin is light in weight, advantageous in workability and economical efficiency, and is widely used as an automotive material. When manufacturing a vehicle rear combination housing, an electric circuit box, a battery, etc. with thermoplastic resin, it is necessary to weld the resin. There are three main types of welding methods. In particular, there are a method of using an adhesive, a method based on frictional heat (vibration welding method), and a method of using heat (hot plate welding method). Among these methods, the method of using an adhesive is undesirable from an environmental point of view because it uses a solvent, and this method also has the disadvantage of having a long cycle time. In the case of the vibration welding method, particles of the powdered resin are scattered, so that the working environment is poor, the design is limited, and there are problems such as contamination of the welded parts. Therefore, this method is only used in limited fields. The hotplate method is most widely used, but this method has the following drawbacks. That is, firstly, when the resin is in contact with the hot plate, a part of the material is present on the hot plate, and thus the carbonized material produced lowers the weld strength to lower the production yield. As a result, the work of removing the resin debris must be carried out periodically. Second, when the resin is pulled out of the hot plate, the string is pulled out of the resin, leaving fine filament formations in the molded part. In particular, this problem is fatal for optical products such as lamp lenses.

In order to solve the above-mentioned problem, a method of using a special sheet in a hot plate welder, or a method of performing welding without contact with a welder is used. However, this method requires a significant cost for the equipment and does not provide a fundamental solution to the above-mentioned problem.

Purpose of the Invention

Accordingly, it is an object of the present invention to solve the above problem by improving the composition, and more particularly, an object of the present invention is that an improved carbon filament of the resin does not remain in the hot plate, and the fine filament of the resin is not attracted It is to provide a resin composition having hot plate weldability.

The present invention relates to a polyester composition containing a polycarbonate resin, in particular a resin composition suitable for use in the manufacture of automobile lamps or the like by a hot-plate welding process.

In particular, the present invention relates to (A) 98 to 1 wt% polyester resin, (B) 1 to 98 wt% polycarbonate resin, (C) 0.5 to 18 wt% core-shell copolymer and (D) 30,000 And a resin composition containing 0.01 to 4% by weight of polytetrafluoroethylene (wherein the total amount of A to D is 100% by weight) having the above number average molecular weight.

In addition, the present invention provides that the core-shell polymer (C) described above is at least one shell-forming compound selected from the group consisting of vinyl aromatic compounds, vinyl cyanide, alkyl acrylates, alkyl methacrylates, acrylic acid and methacrylic acid. And a resin composition which is formed by polymerizing a core composed of a monomer and an acrylate rubber or butadiene rubber.

In the present invention, a resin well known as the polyester resin (A) can be used. Examples of such resins include polycondensed polyesters prepared by the reaction between dicarboxylic acids or derivatives thereof and diols; Polycondensed polyesters produced by the reaction between dicarboxylic acids or their derivatives and cyclic ether compounds; Polycondensed polyester obtained by reaction between a metal salt of dicarboxylic acid and a dihalogen compound; And polycondensation polyester formed by the ring-opening polymerization reaction of the cycle ester compound.

Aliphatic dicarboxylic acids or aromatic dicarboxylic acids may be used as the dicarboxylic acid. Examples of aliphatic dicarboxylic acids include fatty acids such as oxalic acid, succinic acid, adipic acid and the like. Moreover, alicyclic dicarboxylic acid, such as cyclohexanedicarboxylic acid, can be illustrated. Examples of aromatic dicarboxylic acids that can be used include terephthalic acid, isophthalic acid, phthalic acid and chlorophthalic acid and the like. These acids may be used alone or as a combination of two or more acids. Examples of dicarboxylic acid derivatives that can be used also include anhydrides, ester compounds, hydrochlorides, and salts with alkali metals such as potassium and sodium, and the like.

Diols that may be used include both aliphatic diols and aromatic diols. Examples of aliphatic diols include dihydric alcohols such as ethylene glycol, propylene glycol, butane-1,4-diol and hexamethylene glycol and the like, with ethylene glycol and butane-1,4-diol being particularly preferred. Moreover, examples of aromatic diols that can be used include bisphenol A, resorcinol and the like. Such diols may be used alone or as a combination consisting of two or more diols.

Examples of cycle ethers that may be used include ethylene oxide and propylene oxide and the like. Dihalogen compounds that may be used include compounds obtained by replacing two hydroxy groups of the diols described above with halogen atoms (eg chlorine or fluorine). Cyclic esters that can be used include ε-caprolactam and the like.

Particularly preferred polyester resins (A) for use in the present invention are aromatic dicarboxylic acids (especially terephthalic acid, isophthalic acid or ortho-phthalic acid) and polyethylene terephthalates derived from ethylene glycol or butylene glycol, terephthalic acid and the like described above and 1 Polybutylene terephthalate produced from, 4-butanediol. The content of the polyester resin (A) contained in the composition is 98 to 1% by weight of the resin composition, the preferred content is 80 to 5% by weight, more preferably 60 to 15% by weight. If the upper limit is exceeded, impact resistance is lowered. Conversely, if the content is smaller than the lower limit, chemical resistance of the composition is lowered.

Aromatic polycarbonates obtained by generally known phosgene processes or fusion processes (e.g., Japanese Patent Application No. 63-215763 and Japanese Patent Application No. Hei 2-124934) are used as polycarbonate resins of the present invention. It can be used as B). The polycarbonate resin is composed of a carbonate component and a diphenol component. Examples of precursors that can be used to derive the carbonate component include phosgene and diphenyl carbonate. Also, examples of diphenol components that can be used are 2,2-bis (4-hydroxyphenyl) propane (referred to as bisphenol A), 2,2-bis (3,5-dibromo-4-hydroxy Phenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1, -bis (3,5- Dimethyl-4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) decane, 1,4-bis (4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl ) Cyclododecane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) cyclododecane, 4,4-dihydroxydiphenyl ether, 4,4-oxyphenol, 4,4-di Hydroxyphenyl-3,3-dichlorophenyl ether and 4,4-dihydroxy-2,5-dihydroxydiphenyl ether and the like. These phenolic components may be used alone or in combination. In addition, compounds having three or more phenolic hydroxy groups can be used.

Preferred polycarbonate resins (B) for use in the present invention are, for example, LEXAN® 101 and LEXAN® 121, etc. These materials are bisphenol A polycarbonate resins commercially available from General Electric Company. to be. The content of the polycarbonate resin (B) contained in the resin composition is 1 to 98% by weight, preferably 15 to 90% by weight, more preferably 30 to 80% by weight.

Alternatively, component (B) can be an aromatic copolyester carbonate. In addition to the carbonate units derived from generally known aromatic diols, the components also have ester units derived from aromatic diols and aliphatic dicarboxylic acids (C6-C18). As a method for producing an aromatic polycarbonate, a phosgene method or a fusion method which is well known may be used to prepare the aromatic copolyester carbonate (see US Pat. No. 4,238,596, US Pat. No. 4,238,597 and US Pat. No. 3,169,121). .

The core-shell copolymer constituting component (C) of the present invention is a copolymer formed by graft polymerizing one or more shell-forming monomers on a rubber-like core. An example of such a copolymer is a copolymer formed by grafting polystyrene or polymethacrylate as a shell on a core composed of acrylate rubbers, butadiene rubbers, polyorganosiloxanes or synthetic rubbers constituting such rubbers. Core-shell copolymers, methods of making such copolymers, and the use of core-shell copolymers in combination with polycarbonate resins and polyester resins as impact resistance improvers are described, for example, in US Pat. No. 3,864,428, US Pat. , US Pat. No. 4257937 and US Pat. No. 4264487. Furthermore, thermoplastic compositions which are excellent in weatherability and formed by mixing polycarbonate resins and / or polyester resins, polyolefin rubber graft copolymers and core-shell copolymers are described in Japanese Patent Application No. 9-302206. However, these references do not mention the thermal fusion of the resin composition and do not suggest the mixing of the core-shell copolymer and polytetrafluoroethylene.

In a preferred core-shell copolymer for use in the present invention, the core consists of acrylate rubber or butadiene rubber. Acrylate rubber is methyl methacrylate. Rubbers derived from acrylic esters such as ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate and the like. Preferably, such rubber is methyl methacrylate. Obtained from ethyl methacrylate, propyl methacrylate or mixtures thereof. Preferred monomers for forming the shell by graft polymerization on this core consist of one or more monomers selected from the group consisting of vinyl aromatic compounds, vinyl cyanide, alkyl acrylates, alkyl methacrylates, acrylic acid and methacrylic acid. The monomers forming the core and / or shell preferably contain polyfunctional compounds, such as butylene diacrylate or divinylbenzene, which can act as crosslinking agents and / or graft agents. Particular preference is given to methyl methacrylate and methyl methacrylate-butadiene-styrene polymers (MBS) prepared by polymerizing styrene and butadiene rubber. The content of the core-shell copolymer (C) contained in the resin composition is 0.5 to 18% by weight, preferably 1 to 15% by weight, more preferably 3 to 13% by weight. If the content is less than the lower limit, the effect of improving the hot plate weldability is insufficient, while if the content exceeds the upper limit, the moldability and mechanical strength of the composition are poor.

The polytetrafluoroethylene itself constituting component (D) of the present invention is well known. Furthermore, compositions comprising polyester carbonate resins, polycarbonate resins, phosphate esters and polytetrafluoroethylene are described in Japanese Patent Application No. 9-183893, wherein the polytetrafluoroethylene is used to improve flame retardancy. To the phosphate ester. The reference makes no mention of heat weldability and does not suggest a mixture of core-shell copolymer and polytetrafluoroethylene.

The polytetrafluoroethylene constituting the component (D) used in the present invention can be produced by generally known manufacturing methods. Preferably, such polytetrafluoroethylene is prepared by a suspension polymerization method or an emulsion polymerization method.

The number average molecular weight of the polytetrafluoroethylene used for this invention needs to be 30,000 or more. If the molecular weight is smaller than the above value, the effect of improving hot plate weldability is insufficient. This inferential reason is described below, which does not limit the invention. During hot plate welding, the resin in the vicinity of the hot plate melts, but the resin portion far from the hot plate does not melt. Polytetrafluoroethylene with long molecular chains is spread at the melting and non-melting sites of the resin, so that some of the molecular chains are fixed at the non-melting sites and other sites extend to the melting sites of the resin. When the resin is released from the hot plate, the molten resin bonded to the polytetrafluoroethylene chain extending to the melt portion of the resin is tensioned by the non-melt portion so that the molten resin is removed from the hot plate. However, when polytetrafluoroethylene having short molecular chains is used, it is difficult for the polytetrafluoroethylene to extend to the melting portion and the non-melting portion of the resin. As a result, when the resin leaves the hot plate, the polytetrafluoroethylene resin remains on the hot plate together with the molten resin. Therefore, in order to improve hot plate weldability, it is necessary to use polytetraethylene whose molecular weight is more than a certain value.

The content of polytetraethylene (D) used in the resin composition is 0.01 to 4% by weight, preferably 0.1 to 2% by weight, more preferably 0.1 to 1% by weight. If the content is smaller than the lower limit, the effect of improving the hot plate weldability is insufficient. On the other hand, if the content exceeds the upper limit, productivity is reduced when a die well is formed and the resin is extruded.

Hot plate weldability in the composition of the present invention is remarkably improved by using a combination of the core-shell copolymer (C) and polytetrafluoroethylene (D). The effects of the present invention can be expressed as follows without limitation of the present invention. In particular, as described above, the polytetrafluoroethylene constituting the component (D) transfers the molten thermoplastic resin from the hot plate, and the core-shell copolymer constituting the component (C) is transferred by strengthening the melt tension of the resin composition. Prevents the resin from stretching into fine filaments. Moreover, the core-shell copolymer (C) acts to increase the viscosity of the resin composition and also prevents the resin from being stretched into the filaments. Thus, hot plate weldability is markedly improved by the addition of components (C) and (D).

Conventional additives such as colorants (pigments or dyes), heat stabilizers, antioxidants, weathering improvers, lubricants, mold release agents, crystal nucleating agents, plasticizers, flame retardants, rheology modifiers, impact modifiers, antistatic agents and anti-ester exchange agents As long as the object of the present invention is not lost, it can be added to the resin composition of the present invention during mixing or molding of the resin.

There is no particular limitation on the method used to prepare the resin composition of the present invention, and conventional methods can be used satisfactorily. Preferably a melt mixing method is used. Small amounts of solvent may also be used, but are usually not necessary. Examples of devices that can be used are extruders, banbury mixers, rollers and kneaders and the like. Such devices can be operated in batch operation or continuously.

There is no particular limitation on the molding method used, and various kinds of methods can be used. Examples include injection molding, gas-assisted molding, cold and hot circulation molding, blow molding, extrusion molding and thermoforming molding. Injection molding is particularly preferred.

The invention is illustrated in more detail by the following examples. However, the present invention is not limited by these examples.

I) Resin Used

Resin used for an Example and a comparative example is as follows.

Resin Used in Examples

(A) polyester resin

PET: MA-580, Mitsubishi Rayon K.K.

(B) polycarbonate resin

PC: LEXAN 125 (trade name: manufactured by Nippon GE Plastics K.K.)

(C) core-shell copolymer

MBS: KANEACE B-56 (trade name), manufactured by Kanegafuchi Kagaku Kogyo K.K.

(D) polytetrafluoroethylene

TEFN-1: Freon CD-1 (trade name), number average molecular weight (Mn) = 99,000, manufactured by Asahi ICI Fluoropolymers K.K.

Other Resins Used in Comparative Examples

SEBS: KRATON G1651, Shell Kagaku K.K.

SEP: Septone-1001, manufactured by Kurare K.K.

TEFN-2: Lupron L-5 (trade name), number average molecular weight (Mn) = 25,000, manufactured by Daikin Kogyo K.K.

In addition, the molecular weight of polytetrafluoroethylene is determined by the melting of "poly (tetrafluoroethylene) by T. Suwa, M. Takehisa and S. Machi and Melting and Crystallization Behavior of Poly (tetra fluoroethylene) .New Method for Molecular Weight Measurement of Poly (tetra fluoroethylene) Using a Differential Scanning Calorimeter) "[Jr. Appl. Polym. Science, Vol. 17, pp. 3253-3257 (1973).

II) Evaluation Method

In the present invention, hot plate weldability was evaluated for the amount of resin adhering to the plate (hot plate) and the level of filament tension as described below. Detailed evaluation methods are described below together with detailed descriptions of other evaluation methods used.

(1) IZOD impact strength: measured according to ASTM D256 method.

(2) Heat deflection temperature (HDT): measured according to ASTM D648 method at a load of 4.6 kg.

(3) Melt Flow Index (MI): measured according to ASTM D1238 method at a temperature of 266 ° C. and a load of 2.16 kg.

(4) Filament Tensile Level: The teflon sheet was placed on a hot plate heated to 300 deg. C or 370 deg. C, and the sample piece was lightly pressed thereon. The sample pieces used in each case were tested on 1/4 vigo, 1/4 x 1/2 inch cross sections. After heating for 15 seconds, the sample pieces were pulled to examine the cross section. When peeling the pressed cross section, the length of the extended filament-forming resin was measured. This test was run three times and the maximum value calculated was recorded.

(5) Amount of Resin Attached to Plate: The Teflon sheet was placed on a hot plate heated to 300 ° C or 370 ° C, and the sample piece was lightly pressed thereon. The sample pieces used in each case were tested on 1/4 vigo, 1/4 x 1/2 inch cross sections. After heating for 15 seconds, the sample piece was pulled out and the filament tension was observed. The weight of the sample piece was measured before and after the welding test, and the difference between the two calculated values was taken as the amount of resin adhering to the plate. This test was performed three times and the calculated mean value was recorded.

Examples 1-4 and Comparative Examples 1-9

Each component used was mixed in the proportions described in Table 1 below, and each mixture was extruded using an extruder with two shafts at a temperature of 280-300 ° C. and 300-400 rpm to form pellets. Various evaluation sample pieces (described below) were injection molded from the pellets and used for testing. The evaluation results are shown in Table 1 below.

Example Comparative Example One 2 3 4 One 2 3 4 5 6 7 8 9 Ingredients (parts by weight) (A) PET 38 53.7 37.5 17.9 42 40 40 40 38 33 18 38 37.5 (B) PC 51.5 35.8 51.5 71.6 58 55 55 55 52 47 72 51.5 52 (C) MBS 10 10 10 10 - 5 - - 10 20 10 10 - SEBS - - 5 - - - - - 10 SEP - - - 5 - - - - - (D) TEFN-1 0.5 0.5 One 0.5 - - - - - - - - 0.5 TEFN-2 - - - - - - - - - - - 0.5 - Evaluation test IZOD (kgfcm / cm) 57 45 55 72 9 42 24 11 64 45 15 52 45 HDT (℃) 127 125 127 127 135 132 134 135 125 123 132 130 126 MI (g / 10 min) 8 12 7 6 22 18 17 17 19 11 20 17 8 Filament tensile test Filament Tension Level (mm) ¹⁾ One <1 <1 <1 20 < 5 20 < 20 < One <1 One 5 15 Amount of resin attached to the plate (mg) ¹⁾ 4 2 2 2 10 10 11 10 9 6 9 9 4 Filament Tension Level (mm) ²⁾ One 2 One One 20 < 20 20 < 20 < 20 < 2 20 < 20 < 20 < Amount of resin attached to the plate (mg) ²⁾ 2 2 2 2 13 (9) 7 13 15 8 7 13 6 2 1) Hot plate welding test carried out at 370 ° C. 2) Hot plate welding test carried out at 300 ° C.

It is found that when a certain amount of core-shell copolymer (MBS) (Comparative Example 2) is added to a composition containing a polyester resin and a polycarbonate resin (Comparative Example 1), the level of filament tension is greatly reduced. Can be. The rubbers used in Comparative Examples 3 and 4 are not core-shell copolymers and do not have a reinforcing effect on the melt tension of the resin composition. Thus, compared to core-shell copolymers, these rubbers have little effect on reducing the level of filament tension.

Moreover, the content of the core-shell copolymer was comparative example 1 (non-MBS), comparative example 2 (5% by weight MBS), comparative example 5 (10% by weight MBS) and comparative example 6 (20% by weight). The filament tension level decreases in the order of MBS). However, as can be seen from the comparison of Comparative Examples 5 and 6, when the MBS content exceeds a certain level, the heat resistance (HDT) of the resin composition drops, and a problem arises in terms of mechanical strength (IZOD).

From the comparison of Examples 1 to 4 with Comparative Examples 5 and 7, the amount of resin and filament tensile level adhering to the hot plate at high temperature (370 ° C.) was determined with component (D) (ie polytetrafluoro It can be seen that it is further improved by the addition of (roethylene). When rubber (SEBS) other than the core-shell copolymer is added together with polytetrafluoroethylene (D) (Comparative Example 9), there is some improvement in the amount of resin to be attached, but the filament tensile level The improvement of is small compared to Examples 1-4.

Moreover, when the molecular weight of polytetrafluoroethylene is less than 30,000, little improvement is made in the filament tension level and the amount of resin adhering to the plate (Comparative Example 8).

Therefore, in the thermoplastic resin composition of the present invention, hot plate weldability is greatly improved as a result of the presence of the core-shell copolymer (C) and polytetrafluoroethylene (D) having a specific molecular weight in the composition.

Claims (2)

(A) 98 to 1% by weight of polyester resin, (B) 1 to 98% by weight polycarbonate resin, (C) 0.5-18 weight percent core-shell copolymer, and (D) A resin composition containing 0.01 to 4% by weight of polytetrafluoroethylene (wherein the total amount of A to D is 100% by weight) having a number average molecular weight of 30,000 or more. The method of claim 1, The core-shell polymer (C) is an acrylate rubber or with at least one shell-forming monomer selected from the group consisting of vinyl aromatic compounds, vinyl cyanide, alkyl acrylates, alkyl methacrylates, acrylic acid and methacrylic acid A resin composition, which is formed by polymerizing a core composed of butadiene rubber.