JP4574508B2 - Heat-resistant synthetic resin products - Google Patents

Description

  The present invention relates to a synthetic resin product having heat resistance.

In a conventional synthetic resin product with increased crystallinity and heat resistance, for example, the crystallinity of the wall forming the shape is from the thickness direction center of the wall toward the outer and inner surfaces. There is a container configured to rise (see, for example, Patent Document 1).
JP 2002-172681 A

  On the other hand, a synthetic resin container to be sterilized by retort requires a heat sterilization treatment corresponding to, for example, a case where it is held for 30 minutes in an environment of 120 degrees Celsius. Become.

  Further, even in the conventional container, when the conditions of the heat sterilization treatment become severe according to the required use, it is necessary to increase the heat resistance of the container, and there is still room for improvement.

  The problem to be solved by the present invention is to provide a synthetic resin product excellent in heat resistance.

The heat-resistant synthetic resin product of the present invention is molded from, for example, a polyester resin mainly composed of an ethylene terephthalate unit, and the crystallinity of the wall forming the shape of the synthetic resin product is compared with the center position in the thickness direction of the wall, A heat-resistant synthetic resin product whose outer surface side position separated from the center and the inner surface side position are larger, having a depth of 10 μm from the outer surface of the wall portion toward the center position in the thickness direction. A laser beam having an excitation wavelength of 532 nm is applied to the outer surface side position located at the inner surface and the inner surface side position located at a depth of 10 μm from the inner surface of the wall portion toward the center position in the thickness direction. The half-value width of each peak value detected in the vicinity of the wave number 1730 (cm ^-1 ) as scattered light is irradiated to the laser beam at the center in the thickness direction of the wall, and the wave number 1730 (cm ^-1 ) It is characterized by being 75 to 95% of the full width at half maximum of the peak value detected in the vicinity.

  The product according to the present invention is preferably characterized in that a half value width of the peak value at the outer surface side position is equal to or less than a half value width of the peak value at the inner surface side position.

  In the product of the present invention, the half value width of the peak value at the outer surface side position is preferably 85% or more of the half value width of the peak value at the inner surface side position.

The product of the present invention has an outer surface side position located at a depth of 10 μm from the outer surface of the wall portion toward the center position in the thickness direction, and a depth of 10 μm from the inner surface of the wall portion toward the center position in the thickness direction. A laser beam having an excitation wavelength of 532 nm is irradiated to the inner surface side position located at the same position, and the half-value width of each peak value detected near the wave number 1730 (cm ^-1 ) as the scattered light of the laser light is The laser beam is irradiated to the central position in the thickness direction, and it is 75 to 95% of the half-value width of the peak value detected near the wave number 1730 (cm ⁻¹ ) as the scattered light of the laser beam. Even so, it is possible to provide a synthetic resin product having a small volumetric shrinkage ratio and excellent heat resistance.

  Further, in the product of the present invention, if the half value width of the peak value at the outer surface side position is equal to or less than the half value width of the peak value at the inner surface side position, a synthetic resin product with higher heat resistance is provided. Can do.

  Furthermore, in the product of the present invention, if the half-value width of the peak value at the outer surface side position is 85% or more of the half-value width of the peak value at the inner surface side position, a synthetic resin product with even higher heat resistance Can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing a bottle 1 which is an embodiment of the product of the present invention, and FIG. 2 is an enlarged sectional view showing a region A in FIG.

  A bottle 1 shown in FIG. 1 is a so-called PET bottle formed by biaxially stretching blow molding of a PET resin, and includes a mouth portion, a shoulder portion, a trunk portion, and a bottom portion. Reference numeral 10 shown in FIG. 2 is a wall portion that forms the shape of the PET bottle 1. This wall portion 10 has a single-layer structure made of PET resin with different degrees of crystallinity between the outer surface 10a that forms the external shape of the PET bottle 1 and the inner surface 10b that forms the filling space with which the contents come into contact. It is.

  Further, in FIG. 2, reference numeral Pc is the center position in the thickness direction at the thickness T of the wall portion 10, and is located at an equal distance from the outer surface 10a and the inner surface 10b. Symbol Pa is an outer surface side position located at a depth of 10 μm from the outer surface 10a of the wall portion 10 toward the central position Pc, and the depth is represented by ta. Similarly, symbol Pb is an inner surface side position located at a depth of 10 μm from the inner surface 10b of the wall portion 10 toward the central position Pc, and the depth is represented by tb. In this embodiment, the intermediate wall of the wall portion 10 is defined between the outer surface side position Pa and the inner surface side position Pb.

  Such a bottle 1 is such that the crystallinity of the wall portion 10 is higher at the outer surface side position Pa and the inner surface side position Pb than the center position Pc in the thickness T direction, and an excitation wavelength is applied to the bottle 1 by laser Raman spectroscopy. The characteristics in the case of analyzing the three points of the outer surface side position Pa, the inner surface side position Pb, and the center position Pc by irradiating with 532 nm laser light are shown below.

  Laser Raman spectroscopy can analyze the crystal structure and molecular orientation of a target without damaging the target by irradiating the target with laser light and detecting the scattered light (Raman scattered light). It is possible spectroscopy.

When the PET bottle 1 is irradiated with laser light, for example, the peak value RH of Raman scattered light for this laser light is detected in the vicinity of V1 = 1730 (cm ^-1 : Raman shift (wave number)) as shown in PEAK1 in FIG. The peak value RH is a peak due to the carbonyl group. Therefore, the half-value width W of the peak value RH in this embodiment is the width of the intermediate value Rc with respect to the peak value RH in the vicinity of V1 = 1730 (cm ⁻¹ ) as shown in FIG.

That is, the bottle 1 according to the present invention irradiates laser light to the outer surface side position Pa, and the half value width of the peak value RH (a) detected in the vicinity of the wave number 1730 (cm ⁻¹ ) as the Raman scattered light of the laser light. Wa and the inner surface side position Pb are irradiated with the laser beam, and the half-value width Wb of the peak value RH (b) detected near the wave number 1730 (cm ^-1 ) as the scattered light of the laser beam is the center position, respectively. Pc is irradiated with the laser beam, and exhibits a characteristic that becomes 75 to 95% of the half-value width Wc of the peak value RH (c) detected in the vicinity of the wave number 1730 (cm ⁻¹ ) as Raman scattered light of the laser beam.

  According to such a configuration, it is possible to provide a PET bottle excellent in heat resistance with a smaller volumetric shrinkage rate than in the past even when placed in a high temperature state for a long time.

  Further, the bottle 1 shows a characteristic that the half width Wa of the peak value RH (a) at the outer surface side position Pa is equal to or less than the half width Wb of the peak value RH (b) at the inner surface side position Pb. According to such a configuration, a PET bottle with higher heat resistance is obtained.

  Further, in the bottle 1, the half value width Wa of the peak value RH (a) at the outer surface side position Pa is a ratio of 85% or more with respect to the half value width Wb of the peak value RH (b) at the inner surface side position Pb. Show properties. According to such a configuration, the PET bottle has a higher heat resistance.

  Moreover, the PET bottle 1 according to the present embodiment is formed by, for example, the following two-stage blow molding method.

  As a specific example, first, a portion corresponding to a container body portion of a preform made of PET resin is heated to a temperature at which it can be stretch-molded (preform heating step). At this time, the preform is heated by a heater or the like.

  Next, this heated preform is blow molded in a mold (primary blow molding step).

  And the primary blow molded product shape | molded by this primary blow molding process is taken out from a metal mold | die, and it heat-processes (heat processing process). At this time, it is preferable to control the primary blow-molded product to shrink so that the outer diameter of the heat-treated product is the same as or slightly smaller than the inner diameter of the secondary blow-molding mold.

  After the heat treatment of the primary blow-molded product, it is further blow-molded again in a mold having a temperature of 210 degrees Celsius or more (secondary blow molding process).

  Examples of the heat-resistant container of the present invention are shown below.

  Examples 1 to 3 are heat-resistant containers according to the present invention, which are molded by a two-stage blow molding method, and the temperatures of secondary blow molds are 210 ° C, 220 ° C, and 230 ° C, respectively. . The numerical values in parentheses in Table 1 are the ratios of the half-value widths at the outer surface side position and the inner surface side position when the half-value width Wc of the peak value RH (c) at the center position Pc in each example is compared to 100. .

  On the other hand, Comparative Examples 1 and 2 are conventional heat-resistant containers, which are formed by a two-stage blow molding method, and the temperatures of the secondary blow molds are 140 ° C. and 170 ° C., respectively. The numerical values in parentheses in Table 1 are the half values at the outer surface side position Pa and the inner surface side position Pb when compared with the half value width Wc of the peak value RH (c) at the center position Pc of each example as 100. It is the ratio of the price ranges Wa and Wb.

  The measurement points of Examples 1 to 3 and Comparative Examples 1 and 2 are the three points of the outer surface side position Pa, the inner surface side position Pb, and the center position Pc, respectively, in the wall of the bottle body, and each data is The following measurement models and measurement conditions were obtained.

(1) Measurement model:
NRS-3200 laser Raman spectrophotometer (manufactured by JASCO Corporation)
(2) Measurement conditions:
Sample chamber Micro objective x 20 Excitation wavelength 532nm
Diffraction grating 2400L / mm Slit width 50μm

Table 1 shows data indicating the half-value width W of the peak value RH detected in the vicinity of V1 = 1730 (cm ⁻¹ ) as Raman scattered light at each measurement point.

Further, there is a close relationship between the half width W, the density ρ, and the crystallinity Cs, and there is a direct proportional correlation between the reciprocal of the density ρ and the half width W, the crystallinity Cs and the density ρ. The following equation holds between: In the following formula, ρ ₍₁₀₀₎ is the density of 100% crystal, ρ ₍₀₎ is the density of 0% crystal, and ρ is measured by the density gradient tube method (based on JIS K 7112 D method). The density of the target sample.
Cs = ρ ₍₁₀₀₎ × (ρ-ρ ₍₀₎ ) × 100 / {ρ × (ρ ₍₁₀₀₎ -ρ ₍₀₎ )}
From the above relationship, it is shown that the crystallinity increases as the full width at half maximum W decreases.

  In addition, when the heat treatment was performed by immersing the containers of Examples 1 to 3 and Comparative Examples 1 and 2 in 120 degree Celsius hot water for 30 minutes corresponding to the retort sterilization conditions, Almost no deformation was observed above, the volume shrinkage was 1% or less, and it was confirmed that the film had sufficient heat resistance. In Comparative Examples 1 and 2, there was a case where the trunk cross section was deformed to be distorted. Therefore, referring to the above data, it is clear that a synthetic resin product having a small volume shrinkage ratio and excellent heat resistance can be provided even when left in a high temperature state for a long time.

  In addition to bottles and retort containers (pouch containers), the product of the present invention can be applied to synthetic resin products that require heat resistance, such as self-standing containers such as wide-mouth containers and resin trays.

1 is a longitudinal sectional view showing a bottle 1 which is an embodiment of the product of the present invention. FIG. 2 is an enlarged sectional view showing a region A in FIG. It is a characteristic diagram which illustrates the peak of the Raman scattered light detected when a PET resin is analyzed by laser Raman spectroscopy.

Explanation of symbols

1 PET bottle
10 Wall
10a Wall outer surface
10b Wall inner surface

Claims (3)

Compared to the central position in the thickness direction of the wall, the crystallinity of the wall that forms the shape of the synthetic resin product has higher heat resistance at the outer surface side position and the inner surface side position separated from the center. A synthetic resin product having
An outer surface side position located at a depth of 10 μm from the outer surface of the wall portion toward the center position in the thickness direction and an inner surface side located at a depth of 10 μm from the inner surface of the wall portion toward the center position in the thickness direction Each position is irradiated with a laser beam having an excitation wavelength of 532 nm, and the half-value width of each peak value detected as a scattered light of the laser beam in the vicinity of a wave number of 1730 (cm ^-1 ) is the center of the wall in the thickness direction. A synthetic resin product having heat resistance, characterized in that it is 75 to 95% of the full width at half maximum of the peak value detected near the wave number 1730 (cm ⁻¹ ) as a scattered light of the laser light.   2. The synthetic resin product having heat resistance according to claim 1, wherein a half value width of the peak value at the outer surface side position is equal to or less than a half value width of the peak value at the inner surface side position. The heat-resistant synthetic resin according to claim 1 or 2, wherein a half value width of the peak value at the outer surface side position is 85% or more of a half value width of the peak value at the inner surface side position. Product.

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