JP3360544B2 - Method for producing resin composition for thermoforming and resin composition obtained therefrom - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a crystalline or non-crystalline resin composition which is preferable as a general thermoforming raw material such as extrusion molding, and a resin composition obtained by this method. The resin composition of the present invention has a wide temperature range capable of being thermoformed, and has excellent mold followability during molding, and is preferable as a material for various packaging containers such as food packaging and pharmaceutical packaging.

[0002]

2. Description of the Related Art At present, various resins are used as materials for packaging containers of various commodities such as foods and pharmaceuticals. A typical example of such a packaging container is a PTP packaging sheet used for packaging solid pharmaceuticals, and a polyvinyl chloride (hereinafter abbreviated as PVC) sheet has been widely used. A PVC sheet is an excellent sheet that almost satisfies the properties required for PTP packaging, such as moldability, transparency, and impact resistance, but does not have sufficient moisture-proof properties. For this reason, for preparations that require high moisture resistance, PTP packaging is performed, and then pillow packaging is further performed using a laminated film containing aluminum foil, or a composite sheet in which polyvinylidene chloride is coated on a PVC sheet. Is used to improve the moisture resistance. However, such a method is not preferable because the number of steps is increased and the cost of the packaging material is greatly increased. In addition, PVC after use is not preferable because it causes environmental pollution due to incineration.

In order to cope with such a demand for moisture proofing and environmental problems, polypropylene sheets have recently been used in place of PVC. However, polypropylene has a serious industrial problem that thermoformability is extremely poor. That is, polypropylene has a large drawdown due to heat during preheating by thermoforming, and has an extremely narrow optimum molding temperature range of about 2 to 3 ° C. at which a good molded product can be obtained. For this reason, in thermoforming polypropylene, extremely high temperature control is required, and the process management is very difficult with a conventional general-purpose molding machine, and the molding defect rate is high.

[0004] Under these circumstances, various studies have been made on the improvement of the thermoformability of polypropylene.
For example, there has been proposed a method of blending polypropylene with a relatively good moldability, such as polyethylene or ethylene-propylene copolymer, an inorganic filler, or a low-molecular-weight petroleum resin, for modification. For example, at the time of melting, a method of adding high-viscosity polyethylene (low-density polyethylene) and hydrous magnesium silicate powder to high-viscosity polypropylene (Japanese Patent Publication No. 56-15744), or polypropylene to polyethylene (high-density polyethylene) And ethylene-
A method of adding a propylene copolymer (JP-B-63-29)
No. 704), a method of improving molding processability and vibration fatigue resistance using polypropylene and polyethylene having a narrow molecular weight distribution (Japanese Patent Publication No. 532132/1988). A method of adding coalescence (Japanese Patent Publication No. 6-89191) has been proposed.

However, each of these techniques has a certain effect on the improvement of the formability such as sheet softening tension holding time, melt strength, drawability, drawdown, etc. under specific temperature conditions. There is almost no effect on the expansion of the moldable temperature range, which is a substantial indicator of the improvement in formability.

[0006] In addition to the improvement of the moldability of such polypropylene, the moldability of crystalline resins such as polyethylene, polyethylene terephthalate, and polyamide has not yet been satisfactory in terms of industry. Further, there is a demand for further improvement in thermoformability of non-crystalline resins such as polystyrene.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a resin composition including a crystalline resin composition having excellent thermoformability. The resin obtained by the production method of the present invention has a wide moldable temperature range at the time of molding and has excellent followability to a mold at the time of molding.

The present inventors have studied in detail various combinations of resins and kneading conditions from the viewpoints of melting point difference, viscosity ratio and shear rate. As a result, a specific morphology can be obtained by mixing resins having a specific melting point (or glass transition point) difference under a condition having a predetermined viscosity ratio, and such a composition has a high thermoforming point. The present invention was completed based on the finding that the present invention is preferable.

The present invention relates to a method for producing a resin composition obtained by melting and kneading two kinds of resins, a first high melting point resin and a second low melting point resin, wherein the first resin is JIS K 712.
The melting point or the glass transition point by differential scanning calorimetry based on No. 1 is higher by 10 to 100 ° C. than that of the second resin, and the melt kneading is performed based on the melt viscosity (ρH) of the first resin and the melt viscosity of the second resin (ρH). An object of the present invention is to provide a method for producing a thermoforming resin composition carried out at a temperature and a shear rate at which the ratio (ρL / ρH) of (ρL) is 0.05 to 1.0, and a resin composition obtained therefrom. The resin used in the resin composition for thermoforming of the present invention is preferably a crystalline resin.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The resin used in the production of the resin composition of the present invention has a melting point in the case of a crystalline resin and a glass transition point in the case of a non-crystalline resin. Temperature difference of 10 to 100 ° C., preferably 10 to 50 ° C., more preferably 15 to 30 ° C., the first high melting point resin and the second low melting point resin having a temperature difference of 15 to 30 ° C. Use resin. If the temperature difference such as the melting point is out of this range, the moldable temperature range is not widened and the moldability is poor. Such a measurement of the melting point (the same applies to the measurement of the transition point of glass) is performed by differential scanning calorimetry (heat flow rate DSC) based on JIS K7121.

The resin used in the present invention may be either a crystalline resin or an amorphous resin, but the effect of improving the moldability is remarkable because at least one of the composition is a crystalline resin, More preferably, both are compositions of a crystalline resin.

Typical resins used in the production method of the present invention include crystalline resins such as polypropylene, polyethylene, saturated polyester and polyamide, and non-crystalline resins such as polystyrene, polymethyl methacrylate, polyethyl methacrylate and polycarbonate. Crystalline resin is mentioned.

In the production of the resin composition of the present invention, various resins including the above-mentioned resins are appropriately combined and melt-mixed so as to satisfy predetermined requirements in consideration of melting point data well known to those skilled in the art.

[0014] Representative resins among these resins used in the present invention will be described briefly. (Polypropylene) Examples of the type of polypropylene that can be used as one component of the resin composition of the present invention include, for example, known polypropylenes such as propylene homopolymer, block copolymers of propylene and ethylene or α-olefin, and random copolymers, and mixtures thereof. Is mentioned. In particular, when high moisture resistance, transparency and rigidity are required, a homopolymer of propylene is preferred.

(Polyamides) Polyamides include polylactams such as nylon 6, nylon 11, and nylon 12, nylon 6,6, nylon 6,10, nylon 6,
Polyamides comprising dicarboxylic acids and diamines such as 12, nylon 6 / 6,12, nylon 6 / 6,6 / 6,
And 10 copolymerized polyamides.

(Saturated polyester) Examples of the saturated polyester include polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, and polyethylene-2,6-naphthalate.

(Polyethylene) As polyethylene,
For example, any of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and ultra-low-density polyethylene (VLDPE) can be used. When high moisture resistance is required, high density polyethylene is preferably used.

The amount of the first resin selected from the various resins including these resins is 80 to 80% based on the total amount of the composition.
It is 60% by weight, preferably 75 to 60% by weight, more preferably 70 to 61% by weight. If the compounding amount of the high melting point resin is larger than the above range, the moldability is not sufficiently improved, such as the secondary workability when the film is subjected to vacuum / pressure molding. If the amount of the high melting point resin is less than the above range, heat resistance, which is an excellent property of the high melting point resin, cannot be obtained.

The compounding amount of the second resin corresponds to the compounding amount of the high melting point resin, and is 20 to 40% by weight, preferably 25 to 40% by weight, more preferably 30 to 39% by weight based on the total amount of the composition. is there.

In the composition of the present invention, the viscoelastic behavior of the sheet during heating can be precisely controlled over a wide range of temperatures by blending a predetermined amount of the first resin and the second resin having a melting point difference in a specific range. It became possible to control. As a result, the moldability at the time of thermoforming, that is, the moldable temperature range was dramatically increased to about 6 ° C. or more.

The composition of the present invention may further contain, if necessary, additives such as dyes and pigments, stabilizers, plasticizers, antistatic agents without impairing the basic properties and within a hygiene-acceptable range.
UV absorbers, antioxidants, lubricants, nucleating agents, fillers, and the like may be added.

(Production of Resin Composition) In order to produce the resin composition of the present invention, a predetermined amount of the above-mentioned high melting point resin (or high glass transition point resin) and low melting point resin (low glass transition point resin) are prepared. Is melt-kneaded. Such melt kneading is performed by the ratio of the melt viscosity (ρL) of the low melting point resin to the melt viscosity (ρH) of the high melting point resin.
(ρL / ρH) is 0.05 to 1.0, preferably 0.1 to 1.0
It is carried out at a temperature and a shear rate of 1.0, more preferably 0.2 to 0.7. The kneading temperature is typically about 10 to 50 ° C. higher than the melting point of the higher melting point resin, such as about 23 for polypropylene and polybutylene terephthalate.
It is preferred to knead at 0 to 280 ° C. Further, the shear rate at the time of the kneaded resin is large, it is preferably 100 sec ^-1 or more, preferably 200 sec ^-1 or more, more preferably 500 sec ^-1 or more. Melt viscosity (ρL) ratio (ρL /
When ρH) is out of the above range, the morphology of the interpenetrating polymer network having a co-continuous structure cannot be obtained, and the conformability to the mold during molding decreases.

For the melt kneading, an ordinary melt extruder or the like may be used, but in order to form an interpenetrating polymer network structure, kneading is preferably carried out by a twin-screw kneader capable of obtaining high shear.

The resin composition of the present invention can be usually formed into a sheet, film, pellet, powder or the like and used for secondary molding.

In the case of forming a sheet for forming, a known forming method using a T-die method or the like may be employed. The obtained sheet may be subjected to a heat treatment in order to improve the formability, the low-temperature rigidity and the moisture-proof property.

[0026]

EXAMPLES Next, the present invention will be described more specifically based on examples. Each resin used in Examples and Comparative Examples is shown below. The melt viscosity was measured using Capillograph 1C.
Using [Toyo Seiki Seisakusho Co., Ltd.], a shear rate of 121.6 sec ⁻¹ , a length of 10 mm, and a melt kneading temperature shown in Table 1 were used.
The measurement was performed using a capillary having a diameter of 1 mm. For melting point, see DSC220C [Seiko Denshi Kogyo
(Manufactured by Co., Ltd.) at a heating rate of 10 ° C./min.

(Polypropylene) PP (250 ° C .; melt viscosity = 401 Pa · s, 270)
° C; melt viscosity = 318, melting point = 161 ° C) J-ALOMAR MA510 [Japan Polyolefin Co., Ltd.]
Manufactured) (polybutylene terephthalate) PBT (250 ° C .; melt viscosity = 727 Pa · s, 270
° C; melt viscosity = 269 Pa · s, melting point = 224 ° C) DURANEX 700FP [Polyplastics Co., Ltd.]
1030B [manufactured by Ube Industries, Ltd.] PA (250 ° C; melt viscosity = 233 Pa · s, melting point = 1030B [manufactured by Ube Industries, Ltd.] PA (250 ° C; melt viscosity = 1187 Pa · s, melting point = 220 ° C)
22013) 1013B [manufactured by Ube Industries, Ltd.] (polyethylene terephthalate) PET (270 ° C; melt viscosity = 502 Pa · s, melting point =
255 ° C) Diamond Night MA521-H [Mitsubishi Rayon Co., Ltd.]

[Examples 1 to 6 and Comparative Examples 1 to 6] After sufficiently dry blending the respective resins, the shear rate was 121.6 sec at each melt kneading temperature shown in Table 1 using a biaxial kneader.
^-1 to obtain a resin composition for thermoforming.

Sample: A 0.25 mm thick T-die extruded sheet was used.

Formability: Compressed air molding machine [FBP-M
2; manufactured by CK Corporation] under a constant pressure (5 kgf / c
m ² ), the temperature of the hot plate was raised in 1 ° C. units at 160 to 240 ° C., and the sample sheet was molded (diameter; 10 mm, height; 4.
5 mm, R; 1.5 mm). The temperature at which the entire thickness of the obtained molded article was uniform was defined as the moldable temperature, and the temperature range was determined.

Morphology: The resin composition for thermoforming is freeze-fractured with liquid nitrogen, and the fractured surface is observed with an electron microscope (SE).
M), the interpenetrating polymer network structure was evaluated as ○, and the sea-island structure was evaluated as ×.

Tables 1 and 2 show the composition and the results of the measured values.

[0033]

[Table 1] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example of implementation ──────── ────────────────── 1 2 3 4 5 6 ────────────────────────── ───────── [Blending (parts by weight)] PP 21 39 21 39 30 PBT 79 61 30 PA 79 61 PET 70 70 ────────────────── ───────────────── Melting point difference (℃) 63 63 59 59 94 31 Melt kneading temperature (℃) 250 250 250 250 270 270 ρL / ρH 0.55 0.55 0.34 0.34 0.63 0.54 Morphology ○ ○ ○ ○ ○ ○ ─────────────────────────────────── [Thermoformability] Moldable temperature range (℃) 10 17 13 20 18 14 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

[0034]

[Table 2] Comparative example 例────────────────── 1 2 3 4 5 6 ────────────────────────── ───────── [Blending (parts by weight)] PP 100 21 PBT 100 PA 100 PA 100 79 PET 100 ──────────────────────差 Melting point difference (° C) − − − − 59 − Melt kneading temperature (° C) 250 250 250 250 250 270 ρL / ρH − − − − 1.72 − Morphology − − − − × − ─────────────────────────────────── [Thermoformability] Moldable temperature range (° C) 2 3 2 2 4 4 ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

[0035]

The thermoforming composition of the present invention greatly expands the temperature range in which thermoforming is possible and has excellent mold followability during molding, so that thermoforming properties, especially vacuum forming properties, pressure forming, and the like. It is highly suitable and is preferable as a material for various packaging containers such as food packaging and pharmaceutical packaging such as PTP packaging.

[Brief description of the drawings]

FIG. 1 is an electron micrograph showing a cross-sectional structure of a resin composition obtained in Example 3.

FIG. 2 is an electron micrograph showing a cross-sectional structure of a resin composition obtained in Comparative Example 5.

Claims (4)

(57) [Claims] 1. Polypropylene, polyamide and saturated polyester
A method for producing a resin composition obtained by melting and kneading two kinds of resins, a first resin and a second resin , selected from a polyester, wherein the first resin is a differential scan based on JIS K7121. The melting point or glass transition point by calorimetry is 1 more than that of the second resin.
0-100 ° C. higher and the melt kneading is carried out so that the ratio (ρL / ρH) of the melt viscosity (ρL) of the second resin to the melt viscosity (ρH) of the first resin is 0.05.
A method for producing a resin composition for thermoforming, which is carried out at a temperature and a shear rate of up to 1.0. 2. The shear rate during melt kneading is 100 seconds.
^{2. The} method according to claim 1, which is not less than ^-1 . 3. Polypropylene, polyamide and saturated polyester
A resin composition obtained by melting and kneading two kinds of resins, a first resin and a second resin , selected from polyesters . The first resin is obtained by differential scanning calorimetry based on JIS K 7121. Melting point or glass transition point is 1 more than the second resin
Temperature and shear rate that are 0-100 ° C. higher and the ratio (ρL / ρH) of the melt viscosity (ρL) of the second resin to the melt viscosity (ρH) of the first resin is 0.05-1.0. A resin composition for thermoforming comprising an interpenetrating polymer network obtained by melt-kneading under the following conditions. 4. At least one of the first and second resins is a crystalline resin, and the mixing ratio of these two resins is 80 to 60% by weight of the first resin and 80% by weight based on the total amount of the resin composition. The resin composition for thermoforming according to claim 3, wherein the amount of the resin is 2 to 40% by weight.