PROCESSING ADDITIVE, MOLDING COMPOSITION, MASTERBATCH OF PROCESSING ADDITIVE AND MOLDING ARTICLE

Abstract

Provided is a processing additive which can bring about improvements in moldability at Mooney viscosity levels at which the dispersibility in a melt-processable resin is high and which further can work at reduced addition levels. The processing additive contains a fluoropolymer having an acid value of not lower than 0.5 KOH mg/g.

Claims

1. A masterbatch of processing additive comprising a processing additive and a melt-processable resin, wherein the processing additive comprises a fluoroelastomer and an interfacial agent, wherein the content of the fluoroelastomer is more than 0.1% by mass and not higher than 20% by mass based on the sum of the mass of the fluoroelastomer and the mass of the melt-processable resin, and the content of the interfacial agent is 50% to 70% by weight based on the processing additive, wherein the fluoroelastomer has an acid value of from 0.67 to 1.4 KOH mg/g, wherein the fluoroelastomer is a vinylidene fluoride/hexafluoropropylene copolymer, or a vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer, wherein the melt-processable resin consists of a linear low-density polyethylene, wherein a mole percentage of the vinylidene fluoride unit in the fluoroelastomer is 74 to 78 mole percent, and wherein the interfacial agent is a polyethylene glycol.

2. The masterbatch of processing additive according to claim 1, wherein the fluoroelastomer is a vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer.

3. The masterbatch of processing additive according to claim 1, wherein the fluoroelastomer is a vinylidene fluoride/hexafluoropropylene copolymer.

4. A molding composition comprising a processing additive and a melt-processable resin, wherein the processing additive comprises a fluoroelastomer and an interfacial agent, wherein the content of the fluoroelastomer is 0.0001 to 10% by mass based on the sum of the mass of the processing additive and the mass of the melt-processable resin, and the content of the interfacial agent is 50% to 70% by weight based on the processing additive, wherein the fluoroelastomer has an acid value of from 0.67 to 1.4 KOH mg/g, wherein the fluoroelastomer is a vinylidene fluoride/hexafluoropropylene copolymer, or a vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer, wherein the melt-processable resin consists of a linear low-density polyethylene, wherein a mole percentage of the vinylidene fluoride unit in the fluoroelastomer is 74 to 78 mole percent, and wherein the interfacial agent is a polyethylene glycol.

5. The molding composition according to claim 4, wherein the fluoroelastomer is a vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer. 25

6. The molding composition according to claim 4, wherein the fluoroelastomer is a vinylidene fluoride/hexafluoropropylene copolymer.

7. A molded article obtained by molding the molding composition according to claim 4.

8. A masterbatch of processing additive comprising a processing additive and a melt-processable resin, wherein the processing additive comprises a fluoroelastomer and an interfacial agent, wherein the content of the fluoroelastomer is more than 0.1% by mass and not higher than 20% by mass based on the sum of the mass of the fluoroelastomer and the mass of the melt-processable resin, and the content of the interfacial agent is 50% to 70% by weight based on the processing additive, wherein the fluoroelastomer comprises acidic end groups derived from a polymerization initiator that provide an acid value of from 0.67 to 1.4 KOH mg/g, wherein the fluoroelastomer is a vinylidene fluoride/hexafluoropropylene copolymer, or a vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer, wherein the melt-processable resin consists of a linear low-density polyethylene, wherein a mole percentage of the vinylidene fluoride unit in the fluoroelastomer is 74 to 78 mole percent, and wherein the interfacial agent is a polyethylene glycol.

9. A molding composition comprising a processing additive and a melt-processable resin, wherein the processing additive comprises a fluoroelastomer and an interfacial agent, wherein the content of the fluoroelastomer is 32 ppm to 5% by mass based on the sum of the mass of the processing additive and the mass of the melt-processable resin, and the content of the interfacial agent is 50% to 70% by weight based on the processing additive, wherein the fluoroelastomer comprises acidic end groups that are derived from a polymerization initiator and provide an acid value of from 0.67 to 1.4 KOH mg/g, wherein the fluoroelastomer is a vinylidene fluoride/hexafluoropropylene copolymer, or a vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer, wherein the melt-processable resin consists of a linear low-density polyethylene, wherein a mole percentage of the vinylidene fluoride unit in the fluoroelastomer is 74 to 78 mole percent, and wherein the interfacial agent is a polyethylene glycol.

Description

DESCRIPTION OF EMBODIMENTS

[0086] The following examples, including comparative examples, illustrate the present invention in further detail. These examples are, however, by no means limitative of the scope of the present invention.

[0087] The measured values reported in the examples and comparative examples are values determined by the methods mentioned below.

1. Copolymer Composition

[0088] Measurements were made using a .sup.19F-NMR spectrometer (Bruker model AC300P).

2. Acid Value

[0089] Measurements were made by a potentiometric titration method prescribed in JIS K 0070 except that a 0.01 mol/L ethanolic potassium hydroxide solution was used in lieu of the prescribed 0.1 mol/L ethanolic potassium hydroxide solution.

3. Mooney Viscosity

[0090] Measurements were made as ML(1+10) at 121° C. in accordance with ASTM D-1646. The Mooney viscosity data presented in the examples and the comparative examples are the ones obtained under those conditions.

4. Melt Fracture Disappearance Time

[0091] The melt-processable resin alone was extruded in a state of melt fracture occurring over the entire surface until stabilization of a pressure and, thereafter, at the time when the screw came into sight, the materials, including the processing additive, for making up each formulation were fed into the hopper and, taking that point of time as time 0 (zero), the time required for the disappearance of melt fracture and smoothening of the whole surface of the molded article was recorded as the melt fracture disappearance time. The disappearance of melt fracture was confirmed by the eye and by touching.

5. Pressure Drop and Time Required for Pressure Stabilization

[0092] In such an extrusion evaluation as the one to be described later herein, the extrusion pressure drops from the pressure (initial pressure) caused only by the initial charge linear low-density polyethylene containing no processing additive as the processing additive produces its effect and, then, the pressure is stabilized at an almost constant level (stable state pressure). The difference between the initial pressure and the stable state pressure was defined as the pressure drop. The time required for the pressure to arrive at the stable state level was regarded as the time required for pressure stabilization.

(Fluoropolymers)

[0093] As for the fluoropolymers used in Examples 1 to 13, those fluoropolymers (fluoroelastomers) having the respective compositions shown in Table 1 were produced by the polymerization method substantially identical to the first step of Example 1 described in Japanese Kokai Publication S52-62391.

EXAMPLES 1 TO 13 AND COMPARATIVE EXAMPLES 1 TO 9

(Preparation of Processing Additives)

[0094] Each fluoropolymer was ground using a grinder (Rapid R-1528, product of Kawata Mfg Co., Ltd.), and 7 parts by weight of talc (P-2, product of Nippon Talc Co., Ltd.) and 3 parts by weight of silica (Syloblock 45H, product of W. R. Grace & Co.) were added to 100 parts by weight of the ground fluoropolymer, followed by mixing up using a small-size grinding mill (Millser 300DG, product of Iwatani Corporation) to give the processing additive. In Examples 4 to 7, 9 to 11 and 13 and Comparative Examples 3 to 5 and 7 to 9 a predetermined amount of polyethylene glycol (Carbowax™ Sentry™ Polyethylene Glycol 8000 Granular NF (hereinafter referred to as “PEG”), product of Dow Chemical Company) was admixed with each processing additive after the above mixing up, followed by tumbling to give a PEG-containing processing additive.

(Preparation of Masterbatches)

[0095] Thereafter, linear low-density polyethylene (LLDPE 1002YB, product of Exxon Mobil Corporation) was admixed with the above-mentioned processing additive in an amount of 5% by weight based on the total weight of the linear low-density polyethylene and the processing additive, the mixture was fed to a twin-screw extruder (Labo Plastomill 30C150, product of Toyo Seiki Seisaku-Sho, Ltd.) operating at a screw speed of 80 rpm to give the processing additive-containing molded article. The master batch of processing additive consisting of the processing additive and the melt-processable resin was prepared, under the same conditions as in the preparation of the above-mentioned molded article except that the processing additive-containing molded article obtained was mixed up by tumbling and the screw speed was increased to 100 rpm so as to improve the dispersion uniformity of the processing additive in the masterbatch.

[0096] The extrusion conditions were as follows. [0097] (1) Temperatures: cylinder temperature 150° C. to 180° C., die temperature 180° C.; [0098] (2) L/D: 25.

(Extrusion Evaluation 1)

[0099] In Examples 1 to 6 and Comparative Examples 1 to 4, the processing additive-containing masterbatch molded in the twin-screw extruder mentioned above was added to linear low-density polyethylene (LLDPE 1201XV Lot. 0000172879, product of Exxon Mobil Corporation) at an addition level of 1% by weight relative to the total weight of the linear low-density polyethylene and masterbatch, followed by mixing up by tumbling. The thus-obtained masterbatch-containing linear low-density polyethylene was extruded through a single-screw extruder (Rheomex OS, L/D: 33, screw diameter: 20 mm, die diameter: 2 mm, product of Haake, Inc.) at a cylinder temperature of 170° C. to 200° C. and a die temperature of 210° C. and at a screw speed of 30 rpm, and a change in melt fracture were observed. In Example 7, the evaluation was made in the same manner as mentioned above except that the masterbatch addition level was 0.2% by weight, in Comparative Example 5, the evaluation was made in the same manner as mentioned above except that the masterbatch addition level was 0.5% by weight.

[0100] Prior to each test run, linear low-density polyethylene containing 15% by weight of silica was fed into the hopper, the screw speed was increased to 150 rpm, and purging was conducted for about 15 minutes. Thereafter, the same linear low-density polyethylene as used in testing (LLDPE 1201XV Lot. 0000172879, product of Exxon Mobil Corporation) was fed into the hopper and purging was carried out for about 15 minutes. Then, the screw speed was restored to the original 30 rpm, extrusion was performed until stabilization of the temperature and, after confirmation of the restoration of the initial pressure, the next experiment was started. In case of failure in initial pressure restoration, the purging work mentioned above was repeated until initial pressure restoration and, thereafter, the next experiment was started.

[0101] The composition of the fluoropolymer, the composition of the processing additive, the evaluation results and other data as obtained in each example are shown below in Table 1. In Table 1, the amount of the processing additive is an amount of the processing additive relative to the total weight of the linear low-density polyethylene and the masterbatch mentioned above.

TABLE-US-00001 TABLE 1 Processing additive Fluoropolymer composition Acid Processing Time required Melt fracture composition (parts by weight) value additive Pressure for pressure disappearance (mol %) Fluoro- (KOH Mooney amount drop stabilization time VdF HFP TFE polymer Talc Silica PEG mg/g) viscosity (ppm) (MPa) (minutes) (minutes) Example 1 78 22 0 100 7 3 0 1.4 29 500 5.5 34 32 Example 2 74 26 0 100 7 3 0 1.0 45 500 5.3 17 10 Example 3 67 15 18 100 7 3 0 1.3 34 500 5.3 34 30 Example 4 78 22 0 100 7 3 200 1.4 29 500 5.3 11 9 Example 5 74 26 0 100 7 3 200 1.0 45 500 5.2 17 10 Example 6 67 15 18 100 7 3 200 1.3 34 500 5.7 25 24 Example 7 78 22 0 100 7 3 200 1.4 29 100 4.0 31 26 Comp. 78 22 0 100 7 3 0 0.1 45 500 2.8 95 No Ex. 1 disappearance Comp. 78 22 0 100 7 3 0 0.2 36 500 2.5 75 No Ex. 2 disappearance Comp. 78 22 0 100 7 3 200 0.1 45 500 3.8 70 54 Ex. 3 Comp. 78 22 0 100 7 3 200 0.2 36 500 2.8 73 83 Ex. 4 Comp. 78 22 0 100 7 3 200 0.1 45 250 1.4 114 No Ex. 5 disappearance

[0102] As shown in Table 1, the use of the processing additive according to the invention resulted in very rapid disappearance of melt fracture and larger pressure drops as compared with the comparative examples. Furthermore, the effects were more marked in those examples in which PEG was added as the interfacial agent. In Comparative Examples 1 and 2, melt fracture did not completely disappear even after arrival at the stable pressure. Even when the level of addition of the processing additive according to the invention is reduced, sufficient effects are produced, as evidenced in Example 7. In Comparative Example 5, in which the addition level was lowered, the effects of the processing additive could not be produced to a satisfactory extent.

(Extrusion Evaluation 2)

[0103] In Examples 8 to 13 and Comparative Examples 6 to 9, the processing additive-containing masterbatch molded in the twin-screw extruder mentioned above was added to linear low-density polyethylene (LLDPE 1201XV Lot. 512431, product of Exxon Mobil Corporation) at an addition level of 1.5% by weight relative to the total weight of the linear low-density polyethylene and masterbatch, followed by mixing up by tumbling. The thus-obtained masterbatch-containing linear low-density polyethylene was extruded through a single-screw extruder (VS 20 m/m extruder, L/D: 24, screw diameter: 20 mm, die diameter: 2 mm, product of TANABE PLASTICS MACHINERY CO., LTD.) at a cylinder temperature of 230° C. and a die temperature of 230° C. and at a screw speed of 30 rpm, and a change in melt fracture were observed.

[0104] Prior to each test run, linear low-density polyethylene containing 15% by weight of silica was fed into the hopper, the screw speed was increased to 80 rpm, and purging was conducted for about 30 minutes. Thereafter, the same linear low-density polyethylene as used in testing (LLDPE 1201XV Lot. 512431, product of Exxon Mobil Corporation) was fed into the hopper and purging was carried out for about 30 minutes. Then, the screw speed was restored to the original 30 rpm, extrusion was performed until stabilization of the temperature and, after confirmation of the restoration of the initial pressure, the next experiment was started. In case of failure in initial pressure restoration, the purging work mentioned above was repeated until initial pressure restoration and, thereafter, the next experiment was started.

[0105] The composition of the fluoropolymer, the composition of the processing additive, the evaluation results and other data as obtained in each example are shown below in Table 2. In Table 2, the amount of the processing additive is art amount of: the processing additive relative to the total weight of the linear low-density polyethylene and the masterbatch mentioned above.

TABLE-US-00002 TABLE 2 Processing additive Fluoropolymer composition Acid Processing Time required Melt fracture composition (parts by weight) value additive Pressure for pressure disappearance (mol %) Fluoro- (KOH Mooney amount drop stabilization time VdF HFP TFE polymer Talc Silica PEG mg/g) viscosity (ppm) (MPa) (minutes) (minutes) Example 8 78 22 0 100 7 3 0 1.4 29 750 7.2 25 27 Example 9 78 22 0 100 7 3 50 1.4 29 750 6.9 28 27 Example 10 78 22 0 100 7 3 200 1.4 29 750 6.9 30 32 Example 11 78 22 0 100 7 3 400 1.4 29 750 6.3 35 42 Example 12 78 22 0 100 7 3 0 0.67 31 750 7.4 31 30 Example 13 78 22 0 100 7 3 200 0.67 31 750 7.1 27 25 Comp. 78 22 0 100 7 3 0 0.1 45 750 6.1 45 No Ex. 6 disappearance Comp. 78 22 0 100 7 3 50 0.1 45 750 6.3 40 No Ex. 7 disappearance Comp. 78 22 0 100 7 3 200 0.1 45 750 6.1 45 No Ex. 8 disappearance Comp. 78 22 0 100 7 3 400 0.1 45 750 5.6 62 No Ex. 9 disappearance

[0106] As shown in Table 2, melt fracture aid not completely disappear by extruder evaluation of 90 minutes in Comparative Examples 6 to 9. On the other hand, melt fracture completely disappeared in a short time in Examples 8 to 13 in which the processing additive according to the invention was used.

[0107] Furthermore, regardless of ratios of PEG and the fluoropolymer, melt fracture completely disappeared in a short time in Example 8 to 13.

INDUSTRIAL APPLICABILITY

[0108] The processing additive and the masterbatch of processing additive according to the invention, which have the respective constitutions mentioned hereinabove, can be utilized in a wide range of applications, for example in manufacturing various films, a bag, a covering material, a vessel for drinks and the other table utensil, a cable, a pipe, a fiber, a bottle, a gasoline tank, and the other molded article for various industries.