KR100439788B1 - Polycarbonate Resin Composition with High Environmental Stress Crack Resistance - Google Patents

Abstract

Polycarbonate-based resin composition of the present invention (A) 100 parts by weight of a thermoplastic polycarbonate resin; (B) 1 to 10 parts by weight of a polyolefin copolymer having a hydrophilic group introduced into the main chain or the side chain; (C) Phosphorus-based internal lubricant is composed of 0.5 to 4 parts by weight, the hydrophilic group introduced polyolefin copolymer is characterized in that the weight average molecular weight of 100,000 to 1,000,000 g / mol.

Description

Polycarbonate Resin Composition with High Environmental Stress Crack Resistance

Field of invention

The present invention relates to a polycarbonate-based resin composition excellent in environmental stress crack resistance (ESCR) properties. More specifically, the present invention relates to a polycarbonate-based resin composition which improves fluidity and ESCR by introducing a high molecular weight polyolefin in which a hydrophilic group is substituted in a main chain or a side chain in a polycarbonate resin.

Background of the Invention

In general, polycarbonate resins have excellent impact resistance, self-extinguishing, dimensional stability, and heat resistance compared with other resins and are widely used as engineering plastics. However, since polycarbonate resins have very low fluidity compared to general thermoplastic resins, there are many limitations in the application of components requiring precision such as portable electronic devices.

In other words, polycarbonate has a very low fluidity and requires a high processing temperature during molding, which results in degradation of physical properties due to pyrolysis due to overheating of the resin, and high injection pressure and speed during injection molding. Very much residual stress is left in the. Due to the excessive residual stress at this time, the molded article made of polycarbonate is greatly reduced in impact resistance or deformation, and causes cracks on the surface of the injection molded product when exposed to oils, cosmetics, or solvents.

In recent years, as the thickness of plastic injection moldings is accelerated, a higher flowability is required, and a low molecular weight polycarbonate (PC) or a low molecular weight lubricant is introduced as a representative method to improve the flowability of such polycarbonate. There is a way. However, in this case, it is pointed out that the fluidity is improved but the impact strength is decreased. That is, when a low molecular weight polycarbonate is used or an excessive amount of a low molecular weight lubricant is introduced to improve fluidity, there is a disadvantage in that cracks are generated on the surface by solvents used in post processing. In addition, there are reports of problems that easily crack when exposed to oils or cosmetics when using the product.

Therefore, the present inventors add a high molecular weight polyolefin having a hydrophilic group introduced to the polycarbonate in order to overcome the above problems, the impact strength decrease does not occur even when using a low molecular weight polycarbonate or introducing an excess of lubricant, It is to develop a polycarbonate-based resin composition with significantly increased environmental stress cracking resistance.

An object of the present invention is to provide a polycarbonate resin composition excellent in fluidity.

Another object of the present invention is to provide a polycarbonate-based resin composition having excellent environmental stress cracking resistance does not occur in the post-processing process.

Still another object of the present invention is to provide a polycarbonate resin composition having excellent chemical resistance.

The above and other objects of the present invention can be achieved by the present invention described below.

The polycarbonate resin composition of the present invention comprises (A) 1 to 10 parts by weight of a polyolefin copolymer having a hydrophilic group introduced into the main chain or side chain thereof (B), based on 100 parts by weight of the polycarbonate resin; And (C) 0.5 to 4 parts by weight of the phosphorus-based internal lubricant, the detailed description of each of these components is as follows.

(A) polycarbonate resin

Methods of producing polycarbonate resins suitable for the present invention and their use in thermoplastic resin compositions are well known to those of ordinary skill in the art. The polycarbonate resin may be prepared by reacting dihydric phenols with phosgene in the presence of a molecular weight modifier and a catalyst, or may be prepared using an ester interchange reaction of dihydric phenols with a carbonate precursor such as diphenyl carbonate.

Preferred examples of the dihydric phenol are bisphenols, most preferably 2,2-bis (4-hydroxyphenyl) propane (bisphenol-A). Bisphenol-A may be partially or wholly replaced by other diphenols.

Dihydric phenols other than the bisphenol-A include hydroquinone, 4,4'-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) cyclohexane , 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfoxide Halogenated bisphenols such as cyan, bis (4-hydroxyphenyl) ketone, bis (4-hydroxyphenyl) ether, and 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane do.

The polycarbonate resin may be a homopolymer or a copolymer using two or more dihydric phenols, or a mixture thereof. In addition, the polycarbonate resin of the present invention includes a linear polycarbonate, a bracnched polycarbonate, a polyester carbonate copolymer, and the like.

Preferred linear polycarbonate resins are bisphenol A based polycarbonate resins. Branched polycarbonates are preferably prepared by reacting polyfunctional aromatic compounds such as trimellitic anhydride, trimellitic acid and the like with dihydroxyphenol and carbonate precursors. Preferred polyestercarbonate copolymers can be prepared by reacting difunctional carboxylic acids with dihydric phenols and carbonate precursors.

(B) Polyolefin copolymer having a hydrophilic group introduced into the main chain or side chain

The polyolefin copolymer having a hydrophilic group introduced into the main chain or the side chain of the present invention is used as an ESCR reinforcing material to prevent surface cracking of the resin and to improve environmental stress cracking resistance.

Examples of the hydrophilic group include a carbonyl group or an acrylate group such as methyl acrylate and ethyl acrylate. Of these, a carbonyl group is preferable for main chain substitution, and an acrylate group is preferable for side chain substitution.

The polyolefin copolymer having the hydrophilic group introduced therein is selected from one or more of olefinic monomers such as ethylene, propylene, isopropylene, butylene, or isobutylene, and carbon monoxide, methyl acrylate, ethyl acrylate, n- It is prepared by copolymerizing one or more of acrylate monomers such as propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, hexyl methacrylate, or 2-ethylhexyl methacrylate.

The polyolefin having a hydrophilic group introduced into the main chain or side chain of the present invention has a molecular weight of 100,000 to 1,000,000 g / mol, preferably 300,000 to 600,000 g / mol. A polymer having a molecular weight of less than 100,000 g / mol or a polyolefin structure in which a hydrophilic group is not substituted is difficult to apply because of poor compatibility.

In the present invention, the polyolefin having a hydrophilic group introduced into the main chain or the side chain is used in the range of 1 to 10 parts by weight, and most preferably in the range of 2 to 7 parts by weight. If it is less than 1 part by weight, there is no effect of reinforcement, and if it is used more than 10 parts by weight, the mechanical strength such as tensile strength, flexural strength, and flexural modulus is large.

(C) Takeover internal lubricant

In general, the internal lubricant is kneaded with the resin to lower the melt viscosity and to improve molding processability. Therefore, in order to serve as an internal lubricant of the polycarbonate of the present invention, as a low molecular weight material, it has to exhibit very excellent flow characteristics at the polycarbonate processing temperature, and also has excellent compatibility with the polycarbonate.

In the present invention, it is preferable to use a low molecular material in the form of a phosphorus compound compatible with polycarbonate, and to use one or more of triallyl phosphite, triallyl phosphate variant, or triallyl phosphite oligomer. Most preferred.

In the case of the triallyl phosphite oligomer, the repeating unit is preferably 10 or less. When the repeating unit is more than 10, the flow characteristics are lowered and the compatibility with the polycarbonate is also lowered.

In the present invention, the internal lubricant in the form of a phosphorus compound is used in an amount of 0.5 to 4 parts by weight. When using less than 0.5, there is no effect of improving fluidity, and when used in excess of 4 parts by weight, the heat resistance of the polycarbonate is greatly reduced.

The polycarbonate resin composition of the present invention can improve physical properties such as mechanical strength and heat deformation temperature by adding inorganic fillers such as glass fiber, carbon fiber, talc, silica, mica, and alumina in addition to the above components. In addition, the present invention may be prepared by further comprising a thermal stabilizer, antioxidant, light stabilizer, plasticizer, pigment, dye, lubricant and release agent, filler, nucleating agent and antistatic agent according to each use.

The resin composition of the present invention can be produced by a known method for producing a resin composition. For example, the components of the present invention and other additives may be mixed simultaneously, then melt extruded in an extruder and prepared in pellet form.

The polycarbonate resin composition prepared according to the present invention can manufacture various molded articles such as portable mobile communication devices, precision electric and electronic parts, and automobile precision parts, which require chemical resistance at the same time as impact resistance and post-processing.

The invention can be better understood by the following examples, which are intended for the purpose of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

Example

The specifications of (A) polycarbonate resin, (B) polyolefin copolymer having a hydrophilic group introduced into main chain or side chain and (C) phosphorus internal lubricant used in Examples and Comparative Examples are as follows.

(A) polycarbonate resin

A bisphenol-A linear polycarbonate having a weight average molecular weight of 20,000 to 40,000 g / mol was used.

(B) a polyolefin copolymer having a hydrophilic group introduced into the main chain or side chain

A copolymer composed of ethylene / n-butylacrylate / carbon monoxide having a weight average molecular weight of 400,000 was used.

(C) Takeover internal lubricant

Triphenyl phosphite showing compatibility with the polycarbonate resin was used as the internal lubricant.

Table 1 shows the composition and measured physical properties of each component used in Examples and Comparative Examples 1-2. Example uses both a polyolefin copolymer having a hydrophilic group, which is an ESCR reinforcing agent, and a phosphorus compound, which is an internal lubricant, and Comparative Example 1 uses only polycarbonate, and Comparative Example 2 uses only polycarbonate and internal lubricant.

Each component was mixed as in Table 1 to prepare pellets using a twin screw extruder having a diameter of Φ = 45 mm. The prepared pellets were dried at 110 ° C. for 4 hours and then injected into a 10 oz injection machine under molding temperature of 230 to 300 ° C. and mold temperature of 60 to 90 ° C. to prepare a physical specimen.

The prepared specimens were prepared in accordance with ASTM D638, bent over several cylindrical fixtures with different radii, and left at room temperature for 30 hours by applying oleic acid at 30 ° C. The tensile test was performed using a universal testing machine at a rate of 5 mm / min to measure the bending strain at which brittle fracture began to occur, thereby obtaining a critical strain.

Example Comparative Example 1 Comparative Example 2 Furtherance (A) Polycarbonate 94 100 97 (B) Polyolefin copolymer having a hydrophilic group introduced 3 0 0 (C) triphenyl phosphite 3 0 3 Properties MI (g / 10min, 300 ℃, 1.26kg) 17 10 16 Critical Strain (%) 2.4 1.2 0.8

From the results of Table 1, in the case of the embodiment in which the polyolefin copolymer with a hydrophilic group introduced and the phosphorus-based internal lubricant is introduced at the same time, the fluidity and the critical deformation was significantly improved. On the other hand, in Comparative Example 2 in which only phosphorus-based internal lubricant was introduced into the polycarbonate, the fluidity was greatly improved, but the critical strain indicating the ESCR was rather lowered.

The present invention has an effect of providing a polycarbonate resin composition having excellent fluidity, excellent environmental stress cracking resistance and chemical resistance by introducing a high molecular weight polyolefin having a hydrophilic group substituted in a main chain or a side chain thereof to an polycarbonate as an ESCR reinforcing material. .

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (6)

(A) 100 parts by weight of thermoplastic polycarbonate resin; (B) 1 to 10 parts by weight of a polyolefin copolymer having an acrylate group introduced into the side chain; And (C) 0.5 to 4 parts by weight of phosphorus internal lubricant; Polycarbonate resin composition, characterized in that consisting of. The polycarbonate-based resin composition of claim 1, wherein the polyolefin copolymer has a weight average molecular weight of 100,000 to 1,000,000 g / mol. The polycarbonate-based resin composition according to claim 1, wherein a carbonyl group is further introduced into the main chain of the polyolefin copolymer. delete The method of claim 1, wherein the polyolefin copolymer is at least one olefin monomer selected from ethylene, propylene, isopropylene, butylene, or isobutylene; methyl acrylate, ethyl acrylate, n-propyl acrylate, n- At least one acrylate monomer selected from butyl acrylate, 2-ethylhexyl acrylate, hexyl methacrylate, 2-ethylhexyl methacrylate and the like; And carbon monoxide; Polycarbonate-based resin composition characterized in that it is prepared by copolymerizing. The polycarbonate-based resin composition according to claim 1, wherein the phosphorus-based internal lubricant is selected from the group consisting of triallyl phosphite, variant of triallyl phosphite, oligomer of triallyl phosphite, and mixtures thereof.