Resin blend for melting process

Abstract

The present invention relates to a resin blend for a melting process, to a method for manufacturing a resin molding using same, and to a resin molding obtained thereby, the resin blend comprising a first resin and a second resin, wherein the second resin includes a polymer resin having at least one organic functional group selected from the group consisting of an alkyl group having 2 to 20 carbon atoms, an alicyclic ring having 5 to 40 carbon atoms and an aromatic ring having 6 to 40 carbon atoms, and has, with the first resin, a melt viscosity difference of 0.1 to 3,000 Pa*s at a shear rate of 100 to 1,000 s.sup.1 and a processing temperature of the resin mixture, and a glass transition temperature (T.sub.g) difference of 10 C. to 150 C.

Claims

1. A resin blend for a melting process comprising a first resin and a second resin, wherein the first resin comprises an acrylate-based resin, wherein the second resin comprises a (meth)acrylate-based resin to which at least one organic functional group selected from the group consisting of tertiary butyl group, isobornyl group, cyclohexyl group, and phenyl group is introduced, and has a melt viscosity difference of 0.1 to 3,000 Pa*s at a shear rate of 100 to 1,000 s.sup.1 at a processing temperature of the resin blend and a glass transition temperature (T.sub.g) difference of 10 C. to 100 C. with respect to the first resin, wherein the resin blend forms a layer-separated structure in which the second resin forms on a surface of the first resin in the layer-separated structure during melt processing under shear stress, wherein the resin blend has an impact resistance of 6.7 to 8.8 kg*cm/cm in an IZOD test and of 6.5 to 9.1 kg*cm/cm in an IZOD test measured according to ASTM D256, and wherein the resin blend has a pencil hardness of 2H to 3H measured according to ASTM 3363-74.

2. The resin blend of claim 1, wherein the melt viscosity difference between the first resin and the second resin at the shear rate of 100 to 1,000 s.sup.1 at the processing temperature of the resin blend is in a range of 0.1 to 2,000 Pa*s.

3. The resin blend of claim 1, wherein the second resin is a (meth)acrylate-based resin having a tertiary butyl group functional group.

4. The resin blend of claim 1, wherein the second resin is a (meth)acrylate-based resin having an isobornyl functional group.

5. The resin blend of claim 1, wherein the second resin is a (meth)acrylate-based resin having a cyclohexyl functional group.

6. The resin blend of claim 1, wherein the second resin is a (meth)acrylate-based resin having a phenyl functional group.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objects, features and advantages of the present application will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:

(2) FIG. 1 is an SEM image showing a layer-separated cross-section of a molded article prepared in Example 1

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

(3) Hereinafter, exemplary embodiments of the present application will be described in detail. However, the present application is not limited to the embodiments disclosed below, but can be implemented in various forms. The following embodiments are described in order to enable those of ordinary skill in the art to embody and practice the present application.

Experimental Example 1: Measurement of Glass Transition Temperature

(4) Glass transition temperatures of first resins and second resins used in Examples and Comparative Examples were measured using a differential scanning calorimeter (DSC823e commercially available from Mettler-toledo). More particularly, an aluminum fan containing 1 mg of a sample of a first resin or a second resin was installed in a measuring instrument, and a glass transition temperature of the sample was then measured at a temperature of 50 to 300 C. (at a rate of 10 C./min: 2 cycles).

(5) The glass transition temperature of the first resin used in the present application was 70 C., and the glass transition temperature of the second resin used in each of Examples and Comparative Examples was measured to calculate a difference in glass transition temperature between the first resin and the second resin.

Experimental Example 2: Measurement of Melt Viscosity

(6) Melt viscosities of the first resins, the second resins and the test samples obtained in Examples and Comparative Examples were measured using a capillary rheometer (Capillary Rheometer 1501 commercially available from Gottfert).

(7) More particularly, a capillary die was attached to a barrel, and the second resin, the first resin or the test sample was then put into the barrel in three divided doses. Thereafter, the shear viscosity (Pa*s) of the second resin, the first resin or the test sample was measured at a processing temperature of 240 C. and a shear rate of 100 to 1,000 s.sup.1.

Experimental Example 3: Observation of Cross-Sectional Shape

(8) The test samples prepared in Examples and Comparative Examples were subjected to a low-temperature impact test, and fracture surfaces of the test samples were then etched with THF vapor, and layer-separated cross-sectional shapes of the test samples were observed using an SEM.

(9) Meanwhile, to measure thicknesses of the layer-separated first resin layer, second resin layer and interfacial layer, the cross-sections of the test samples prepared in the following Examples and Comparative Examples were cut at a temperature of 120 C. using a diamond blade of microtoming equipment (Leica EM FC6), and smoothed. The microtomed smooth cross-sections of the test samples were dipped in a 1,2-dichloroethane solution (10% in EtOH), etched for 10 seconds, and then washed with distilled water. The different portions of the cross-sections were etched to different extents according to the contents of the first resin and the second resin, and observed using an SEM. That is, the first resin layer, the second resin layer and the interfacial layer may be observed by a shade difference, as viewed from a surface of the test sample at an angle of 45. Then, the thickness of each layer may be measured using the results.

Experimental Example 4: Experiment for Measuring Impact Strength

(10) Impact strengths of the test samples prepared in Examples and Comparative Examples were measured according to the ASTM D256 standard. More particularly, energy (Kg*cm/cm) required to destroy a test sample having a V-shaped notch when a weight hung on the end of a pendulum was dropped on the test sample was measured using an impact tester (Impact 104 commercially available from Tinius Olsen). The and test samples were measured five times to calculate average energy values.

Experimental Example 5: Experiment for Measuring Pencil Hardness

(11) Surface pencil hardness of the test samples prepared in Examples and Comparative Examples was measured under a constant load of 500 g using a pencil durometer (commercially available from ChungbukTech). Scratches were applied to a reference pencil (commercially available from Mitsubishi) at a constant angle of 45 while altering the pencil hardness from 6B to 9H, and a surface change of the pencil was observed (ASTM 3363-74). The pencil hardness of the test sample was calculated as an average value of the experiments which were performed 5 times.

Experimental Example 6: Surface Analysis Using Infrared Spectrometer (IRS)

(12) An UMA-600 infrared microscope equipped with a Varian FTS-7,000 spectroscope (Varian, USA) and a mercury cadmium telluride (MCT) detector was used, and spectrum measurement and data processing were performed using Win-IR PRO 3.4 software (Varian, USA). The measurement conditions were as follows. Germanium (Ge) attenuated total reflection (ATR) crystals having a refractive index of 4.0. Mid-infrared spectra are scanned 16 times using an ATR method with a spectral resolution of 8 cm.sup.1 at wavelengths spanning from 4,000 cm.sup.1 to 600 cm.sup.1. Internal reference band: carbonyl group of acrylate (CO str., approximately 1,725 cm.sup.1). Innate component of first resin: butadiene compound [CC str. (approximately 1,630 cm.sup.1) or CH out-of-plane vib. (approximately 970 cm.sup.1)].

(13) Peak intensity ratios [I.sub.BD(CC)/I.sub.A(CO)] and [I.sub.BD(out-of-plane)/I.sub.A(CO)] were calculated, and spectrum measurements were performed five times on different regions in one sample to calculate an average value and a standard deviation.

Example 1

(14) (1) Preparation of Second Resin

(15) 1,500 g of distilled water and 4 g of an aqueous solution including a dispersing agent (2% polyvinyl alcohol) were put into a 3 L reactor, and dissolved. Thereafter, 560 g of methyl methacrylate, 240 g of tert-butyl methacrylate, 2.4 g of a chain transfer agent, n-dodecylmercaptan, and 2.4 g of an initiator, azodiisobutyronitrile, were further added into the reactor, and mixed while stirring at 400 rpm. The resulting blend was reacted at 60 C. for 3 hours to perform polymerization, and cooled to 30 C. to obtain a second resin in the form of beads. Then, the second resin was washed three times with distilled water, dehydrated, and dried in an oven.

(16) (2) Preparation of Resin Blend and Molded Article Using the Resin Blend

(17) 7 parts by weight of the second resin was mixed with 93 parts by weight of the first resin (a thermoplastic resin including methyl methacrylate at 60% by weight, acrylonitrile at 7% by weight, butadiene at 10% by weight, and styrene at 23% by weight), and the resulting blend was then extruded at a temperature of 240 C. in a twin screw extruder (commercially available from Leistritz) to obtain a pellet. Thereafter, the pellet was injected at a temperature of 240 C. in an EC10030 injector (commercially available from ENGEL) to prepare a test sample of a resin-molded article having a thickness of 3,200 m.

(18) (3) Measurement of Physical Properties of Test Sample

(19) The physical properties of the test sample prepared as described above were measured. As a result, it was revealed that the second resin layer had a thickness of 75 m, the interfacial layer had a thickness of 25 m, the melt viscosity difference was 300 Pa*s, the second resin had a glass transition temperature (T.sub.g) of 106 C., the impact strengths were 7.1 kg.Math.cm/cm in the case of IZOD and 6.5 kg.Math.cm/cm in the case of IZOD , the pencil hardness was 2.5H, and the layer separation took place. The peak intensity ratio [I.sub.BD(CC)/I.sub.A(CO)] measured by the infrared spectrometer was 0.0125 on average with a standard deviation of 0.0004, and the peak intensity ratio [I.sub.BD(out-of-plane)/I.sub.A(CO)] was 0.413 on average with a standard deviation of 0.0026.

Example 2

(20) A test sample having a thickness of 3,200 m was prepared in the same manner as in Example 1, except that 560 g of methyl methacrylate and 240 g of cyclohexyl methacrylate were used as monomers instead of 560 g of methyl methacrylate and 240 g of tert-butyl methacrylate.

(21) The physical properties of the test sample prepared as described above were measured. As a result, it was revealed that the second resin layer had a thickness of 76 m, the interfacial layer had a thickness of 23 m, the melt viscosity difference was 410 Pa*s, the second resin had a glass transition temperature (T.sub.g) of 102 C., the impact strengths were 8.8 kg.Math.cm/cm in the case of IZOD and 9.1 kg.Math.cm/cm in the case of IZOD , the pencil hardness was 2H, and the layer separation took place.

Example 3

(22) A test sample having a thickness of 3,200 m was prepared in the same manner as in Example 1, except that 560 g of methyl methacrylate and 240 g of phenylmethacrylate were used as monomers instead of 560 g of methyl methacrylate and 240 g of tert-butyl methacrylate.

(23) The physical properties of the test sample prepared as described above were measured. As a result, it was revealed that the second resin layer had a thickness of 79 m, the interfacial layer had a thickness of 20 m, the melt viscosity difference was 390 Pa*s, the second resin had a glass transition temperature (T.sub.g) of 107 C., the impact strengths were 8.5 kg.Math.cm/cm in the case of IZOD and 8.9 kg.Math.cm/cm in the case of IZOD , the pencil hardness was 2H, and the layer separation took place.

Example 4

(24) A test sample having a thickness of 3,200 m was prepared in the same manner as in Example 1, except that 560 g of methyl methacrylate and 240 g of isobornyl methacrylate were used as monomers instead of 560 g of methyl methacrylate and 240 g of tert-butyl methacrylate.

(25) The physical properties of the test sample prepared as described above were measured. As a result, it was revealed that the second resin layer had a thickness of 76 m, the interfacial layer had a thickness of 21 m, the melt viscosity difference was 310 Pa*s, the second resin had a glass transition temperature (T.sub.g) of 123 C., the impact strengths were 8.1 kg.Math.cm/cm in the case of IZOD and 8.4 kg.Math.cm/cm in the case of IZOD , the pencil hardness was 2H, and the layer separation took place.

Example 5

(26) A test sample having a thickness of 3,200 m was prepared in the same manner as in Example 2, except that 79 parts by weight of the first resin and 21 parts by weight of the second resin were used instead of 93 parts by weight of the first resin (a thermoplastic resin including methyl methacrylate at 60% by weight, acrylonitrile at 7% by weight, butadiene at 10% by weight and styrene at 23% by weight) and 7 parts by weight of the second resin.

(27) The physical properties of the test sample prepared as described above were measured. As a result, it was revealed that the second resin layer had a thickness of 94 m, the interfacial layer had a thickness of 65 m, the melt viscosity difference was 410 Pa*s, the second resin had a glass transition temperature (T.sub.g) of 102 C., the impact strengths were 6.7 kg.Math.cm/cm in the case of IZOD and 6.8 kg.Math.cm/cm in the case of IZOD , the pencil hardness was 3H, and the layer separation took place.

Example 6

(28) A test sample having a thickness of 3,200 m was prepared in the same manner as in Example 1, except that 2.4 g of n-dodecylmercaptan and 3.2 g of azobisisobutyronitrile were used instead of 2.4 g of n-dodecylmercaptan and 2.4 g of azobisisobutyronitrile.

(29) The physical properties of the test sample prepared as described above were measured. As a result, it was revealed that the second resin layer had a thickness of 79 m, the interfacial layer had a thickness of 24 m, the melt viscosity difference was 360 Pa*s, the second resin had a glass transition temperature (T.sub.g) of 105 C., the impact strengths were 4.3 kg.Math.cm/cm in the case of IZOD and 4.1 kg.Math.cm/cm in the case of IZOD , the pencil hardness was 2H, and the layer separation took place.

Example 7

(30) A test sample having a thickness of 3,200 m was prepared in the same manner as in Example 1, except that 400 g of methyl methacrylate and 400 g of cyclohexyl methacrylate were used instead of 560 g of methyl methacrylate and 240 g of tert-butyl methacrylate.

(31) The physical properties of the test sample prepared as described above were measured. As a result, it was revealed that the second resin layer had a thickness of 76 m, the interfacial layer had a thickness of 25 m, the melt viscosity difference was 440 Pa*s, the second resin had a glass transition temperature (T.sub.g) of 93 C., the impact strengths were 7.1 kg.Math.cm/cm in the case of IZOD and 7.0 kg.Math.cm/cm in the case of IZOD , the pencil hardness was 2H, and the layer separation took place.

Comparative Example 1

(32) 100 parts by weight of a pellet formed of a first resin (a thermoplastic resin including methyl methacrylate at 60% by weight, acrylonitrile at 7% by weight, butadiene at 10% by weight, and styrene at 23% by weight) was dried in an oven, and injected at a temperature of 240 C. in an EC10030 injector (commercially available from ENGEL) to prepare a test sample having a thickness of 3,200 m.

(33) The physical properties of the test sample prepared as described above were measured. As a result, it was revealed that the impact strengths were 9.9 kg.Math.cm/cm in the case of IZOD and 10.0 kg.Math.cm/cm in the case of IZOD , and the pencil hardness was F.

Comparative Example 2

(34) 90 parts by weight of the first resin (a thermoplastic resin including methyl methacrylate at 60% by weight, acrylonitrile at 7% by weight, butadiene at 10% by weight and styrene at 23% by weight) was mixed with 10 parts by weight of PMMA (LGMMA IF870), and the resulting blend was the extruded at a temperature of 240 C. in a twin screw extruder (commercially available from Leistritz) to obtain a pellet. Thereafter, the pellet was injected at a temperature of 240 C. in an EC10030 injector (commercially available from ENGEL) to prepare a test sample having a thickness of 3,200 m.

(35) The physical properties of the test sample prepared as described above were measured. As a result, it was revealed that the second resin layer had a thickness of 4 m, the thickness of the interfacial layer was not measurable, the melt viscosity difference was 270 Pa*s, the second resin had a glass transition temperature (T.sub.g) of 104 C., the impact strengths were 5.2 kg.Math.cm/cm in the case of IZOD and 4.9 kg.Math.cm/cm in the case of IZOD , the pencil hardness was H, and the layer separation did not take place.

Comparative Example 3

(36) A test sample having a thickness of 3,200 m was prepared in the same manner as in Example 1, except that 560 g of methyl methacrylate and 240 g of normal hexyl methacrylate were used instead of 560 g of methyl methacrylate and 240 g of tert-butyl methacrylate.

(37) The physical properties of the test sample prepared as described above were measured. As a result, it was revealed that the second resin layer had a thickness of 81 m, the interfacial layer had a thickness of 17 m, the melt viscosity difference was 460 Pa*s, the second resin had a glass transition temperature (T.sub.g) of 62 C., the impact strengths were 9.5 kg.Math.cm/cm in the case of IZOD and 9.3 kg.Math.cm/cm in the case of IZOD , the pencil hardness was HB, and the layer separation took place.

Comparative Example 4

(38) 100 parts by weight of a pellet formed of a first resin (a thermoplastic resin including methyl methacrylate at 60% by weight, acrylonitrile at 7% by weight, butadiene at 10% by weight, and styrene at 23% by weight) was dried in an oven, and injected at a temperature of 240 C. in an EC10030 injector (commercially available from ENGEL) to prepare a test sample.

(39) The test sample was coated with an anti-pollution hard coating solution (including DPHA at 17.5% by weight, PETA at 10% by weight, perfluorohexylethyl methacrylate at 1.5% by weight, a urethane acrylate (EB 1290 commercially available from SK Cytech) at 5% by weight, methyl ethyl ketone at 45% by weight, isopropyl alcohol at 20% by weight, and a UV initiator (IRGACURE 184 commercially available from Ciba) at 1% by weight), which was prepared by the present inventors to include a multifunctional acrylate, using Mayer bar #9, and then dried at a temperature of 60 to 90 C. for approximately 4 minutes to form a film. Then, the coating composition was cured by irradiation with UV rays at an intensity of 3,000 mJ/cm.sup.2 to form a hard coating film.

(40) The hard coating film had a pencil hardness of 3H, and both the peak intensity ratios [I.sub.BD(CC)/I.sub.A(CO)] and [I.sub.BD(out-of-plane)/I.sub.A(CO)] measured by the infrared spectrometer were 0 on average with a standard deviation of 0.

(41) As described above, it was confirmed that, when the resin blends prepared in Examples were used, the layer separation between the resin layers took place during a melt processing process, and the high-hardness resin was distributed on a surface of the resin-molded article due to such layer separation, thereby making it possible to exhibit excellent surface hardness without performing an additional coating or painting process.

(42) On the other hand, it was confirmed that use of the resin blends prepared in Comparative Examples did not cause occurrence of the layer separation between the resin layers, and the prepared resin-molded articles also had relatively low surface hardness, and thus could not be generally used for electronic products, automotive parts and the like without performing an additional coating or painting process.