JP4415938B2 - Member for molding molten resin mass - Google Patents

Description

  The present invention relates to a member for handling a synthetic resin such as a polyester resin and an olefin resin in a molten state, and more specifically, a molten resin mass such as a polyester resin and an olefin resin extruded from an extruder and cut into a predetermined size. , A holding member at the time of being supplied to a compression mold and molded into a preform (preform), a guide member (throat) to the mold, or a compression mold for a preform using the molten resin lump, etc. This relates to a member for compression molding.

Conventionally, a synthetic resin container formed of a polyester resin such as polyethylene terephthalate has been widely used for a beverage container or the like. As a manufacturing apparatus of such a synthetic resin container, as shown in JP 2000-280248 A, first, after cutting the molten synthetic resin extruded from the extrusion nozzle of the extruder into a predetermined size, After being held by the holding mechanism 22 provided with the clamping members 30 and 32, the female is dropped into a throat 56 having a reverse frustoconical shape and an inner surface with an unevenness of 0.2 to 100 μm and a pitch of 0.2 to 800 μm. The molten resin mass is compression-molded to form a bottomed cylindrical preform by supplying the male mold 54 into the female mold 48 and then biaxially stretching the preform. It has been proposed to produce a synthetic resin container by blow molding.
In a compression molding member used for molding such a preform (for example, the holding mechanism 22 including the clamping members 30 and 32, the throat 56, the female die 48, etc.), the molten resin mass is transferred to the throat 56. The sliding property of the holding mechanism 22 at the time, the sliding property of the throat 56 when supplying the molten resin mass to the female die 48, and the releasing property of the preform after the compression molding from the female die 48 are required.
The above-mentioned slipperiness and releasability are the surface scratches, wrinkles, dullness, or surface glossiness and transparency of the synthetic resin container after biaxial stretch blow molding, which is the final product using this preform. Affects.
Further, in such compression molding, as shown in JP-A-2000-62008, poor appearance such as wrinkles on the side wall of the preform due to various fluctuations in the manufacturing process, asymmetry during biaxial stretch blow heating As a means to prevent the appearance of the biaxially stretched blow molded container due to deformation, etc., at least part of the surface of the preform is made into a pear surface, and the pear surface of the biaxially stretched blow molded part of the preform It has been proposed that the unevenness amount h is 0.2 to 50 μm and the pitch is 0.2 to 800 μm.
Further, in order to prevent adhesion of polyester resin, oligomer or additive on the inner surface of the biaxially stretched blow mold using polyester resin, as shown in JP-A-2002-18858, molding of the inner surface of the mold is performed. A hard layer 2 made of a metal or a compound thereof is provided on a metal substrate 1 on the surface, and a contamination prevention layer 3 is provided on the hard layer 2, and the average surface roughness (Ra) of the contamination prevention layer 3 is Ra ≦ 0.1 μm (JIS B 0601-1994), and it has been proposed that the thickness of the contamination prevention layer 3 be 0.3 to 10 μm fluororesin.

However, the treatment only with pear ground disclosed in Japanese Patent Application Laid-Open No. 2000-280248 and Japanese Patent Application Laid-Open No. 2000-62008 is effective for preventing adhesion of resin components to some extent, but continuous production over a long period of time. In some cases, the resin component adheres and accumulates on the pear base portion of the compression molding member such as the holding mechanism 22, the throat 56 or the female mold 48, and the adhesiveness increases, and the holding resin 22 and the throat 56 make the molten resin lump smoothly. It cannot be supplied to the next process, and in the female mold 48, the releasability of the compression-molded preform from the female mold 48 is lowered.
And since it is difficult to remove the resin component once deposited on the pear ground portion, the compression molded member must be frequently cleaned.
Japanese Patent Laid-Open No. 2002-18858 discloses a biaxial stretch blow molding mold using a preform made of a polyester resin, wherein the mold has an average surface roughness made of a metal substrate 1, a hard layer 2 and a fluororesin. The anti-contamination layer 3 having a thickness of Ra ≦ 0.1 μm and 0.3 to 10 μm is formed, and the preform temperature at the biaxial stretch blow molding is performed at a glass transition point (Tg) to 120 ° C. As in the present invention, it is completely different from a compression molding member using a molten resin lump of 270 to 290 ° C. under a higher temperature condition than that of the above-mentioned JP-A No. 2002-18858. The configuration is not enough.
That is, in the configuration of Japanese Patent Application Laid-Open No. 2002-18858, after holding a high-temperature molten resin lump cut to a predetermined size, dropping into a female mold (compression mold) by a throat, supply, and after compression molding The releasability of the bottomed cylindrical preform from the female mold cannot be improved reliably.
An object of the present invention is to solve the above-mentioned problems, to prevent adhesion of resin components for a long time, and to stably perform resin molding by compression molding using a resin material composed of a molten resin lump for a long time. With the goal.
According to the present invention, the metal substrate surface is a rough surface, the fluororesin coating layer is formed on the metal substrate surface, the fluororesin coating layer is a rough surface, and the molten resin mass and the fluororesin coating layer surface are A member for compression molding of a molten resin mass is provided in which the static friction coefficient is set to 1.7 or less.
In the present invention,
(1) The rough surface of the metal substrate has an average surface roughness (Ra JIS B 0601-1994) of 0.1 to 3 μm, and a 10-point average roughness (Rz JIS B 0601-1994) of 0.5 to. 16 μm,
(2) The thickness of the fluororesin coating layer is set to an average film thickness of 0.01 to less than 0.3 μm,
(3) The metal substrate is made of aluminum, stainless steel or steel,
(4) forming an intermediate layer composed of a metal oxide layer, a metal hydroxide layer or a silane coupling layer between the metal substrate and the fluororesin coating layer;
Is preferred.

  FIG. 1 is a sectional view showing an embodiment of a member for compression molding of a molten resin lump according to the present invention, and FIG. 2 is a schematic view showing an apparatus for producing a preform by compression molding.

When the molten resin mass compression molding member of the present invention, that is, the molten resin mass extruded from an extruder and cut into a predetermined size is supplied to a compression molding die and molded into a preform (preform) FIG. 1 shows a cross-sectional structure of a compression molding member such as a holding member, a guide member (throat) to a mold, or a preform compression molding mold using the molten resin lump.
The molten resin lump compression molding member 1 of the present invention has a roughened surface after the metal substrate 10 is cut into the compression molding member described above, and a fluororesin is applied to the roughened metal substrate 10 surface. The coating layer 20 is formed and the surface of the fluororesin coating layer 20 is roughened.
The surface of the fluororesin coating layer 20 has a coefficient of static friction of 1.7 or less with the molten resin, and when the molten resin lump after cutting is released after being held by the holding member, or a compression molding die by the guide member The slipperiness at the time of supply to the mold and the releasability from the mold after the preform molding by the compression molding mold are improved.
This static friction coefficient depends on the resin material of the molten resin mass, the temperature, the presence / absence of the fluororesin layer, and the surface roughness thereof. After forming the fluororesin coating layer in consideration of the resin material, a known rough surface is appropriately used. The static friction coefficient may be reduced to 1.7 or less by the conversion treatment, and if the static friction coefficient exceeds 1.7, the slipping property and the release property are lowered, and it is used as a member for compression molding of the above-described molten resin lump. Can not.
The static friction coefficient is determined by providing an angle (θ where the molten resin lump starts to slide when the fluororesin coating layer is provided on the surface of the metal substrate, the molten resin lump is dropped thereon, the flat plate provided with the fluororesin coating layer is inclined. ₀ ), μ ₀ = tan θ ₀ is defined.
Here, μ ₀ is a coefficient of static friction, and θ ₀ is an angle at which sliding started.
The surface properties of the metal substrate 10 on which the fluororesin coating layer 20 is formed have an average surface roughness (Ra JIS B 0601-1994) of 0.1 to 3 μm and an average roughness of 10 points (Rz JIS B 0601-1994). ) Is preferably 0.5 to 16 μm.
When the average surface roughness (Ra) is less than 0.1 μm and the 10-point average roughness (Rz) is less than 0.5 μm, the slipping property or mold release property between the compression molding member 1 and the molten resin lump is obtained. Inferior, the molten resin lump cannot be smoothly supplied to the next process or released from the compression mold.
On the other hand, when the average surface roughness (Ra) exceeds 3 μm and the 10-point average roughness (Rz) exceeds 16 μm, the molten resin lump is a concave portion on the surface of the fluororesin coating layer 20 of the compression molding member 1. Bite into the mold, the mold release property and slipperiness become inferior, and after molding the preform by compression molding, there is a tendency that the outer surface of the synthetic resin container manufactured by biaxial stretch blow molding becomes cloudy, A range is preferred.
Further, the surface properties of the metal substrate 10, that is, the surface roughness is reflected in the surface roughness of the fluororesin coating layer 20 formed on the surface, and as a result, the static friction coefficient of the fluororesin coating layer 20 is affected. To do.
The fluororesin coating layer 20 is formed on the surface of the metal substrate 10 with an average thickness of 0.01 to less than 0.3 μm.
The fluororesin coating layer 20 is formed in order to improve the slipperiness by suppressing the adhesion of the resin component of the molten resin mass such as polyester resin, and the thickness of the layer is preferably in the above range, If it is less than 0.01 μm, the coating uniformity on the metal substrate is also impaired, and coating defects are likely to occur.
On the other hand, if it exceeds 0.3 μm, it fills the rough surface irregularities formed on the metal substrate 10, the rough surface state is not reflected on the surface of the fluororesin coating layer 20 and the thermal conductivity is deteriorated, The compression molding member in compression molding that handles high-temperature molten resin lumps is cooled from the substrate side, but the cooling effect is also reduced, so in continuous production over a long period of time, the resin component is added to the compression molding member. Adhesion increases and becomes a hindrance to stable continuous production over a long period of time.
In addition, by making the fluororesin coating layer 20 into a thin film in this way, the surface properties of the metal substrate 10 are reflected on the surface of the fluororesin coating layer 20.
As the metal substrate 10 of the fluororesin-coated member 1, it is preferable to use steel, stainless steel, aluminum alloy or the like.
Further, in order to improve the adhesion between the metal substrate 10 and the fluororesin coating layer 20, a metal oxide layer, a metal hydroxide, or a silane coupling is provided between the metal substrate 10 and the fluororesin coating layer 20. It is preferable to form an intermediate layer made of an agent.
Examples of the method for forming the metal oxide layer include chromate treatment, phosphate treatment, oxalate treatment, iron oxide treatment, zirconium salt treatment and the like.
Examples of the phosphate treatment include films of iron phosphate, zinc phosphate, zinc calcium phosphate, manganese phosphate, and the like.
When the metal substrate 10 is made of an aluminum alloy, there are many treatment methods such as an oxide film forming treatment mainly composed of sodium carbonate and sodium chromate, and a treatment method mainly composed of chromic acid and phosphoric acid. When the material 10 is made of stainless steel, an oxalate film forming method can be used.
Examples of the metal hydroxide layer include chromium hydroxide treatment, and examples of the silane coupling layer include methods using various silane coupling agents.
And the thickness of these intermediate layers is preferably in the range of 0.005 μm to 0.1 μm, and if the thickness is less than 0.005 μm, it does not contribute to improving the adhesion of the fluororesin coating layer, When the thickness exceeds 0.1 μm, the intermediate layer itself is not a strong film and becomes brittle. Similarly, the fluororesin coating layer may be peeled off.
Examples of the method for forming these intermediate layers include spray coating, dipping, and electrolytic treatment on the surface of the metal substrate 10.
As the fluororesin used for the fluororesin coating layer 20, any known fluororesin is used. Polytetrafluoroethylene, tetrafluoroethylene / hexafluoropropylene copolymer, tetrafluoroethylene / perfluoro Alkyl vinyl ether copolymers and their modified epoxy resins, modified acrylic resins, modified block acrylic resins, or amorphous solvent-type tetrafluoroethylene / perfluoro (2,2-dimethyl-1,3- A dioxole) copolymer or the like can be used alone or in combination.
These fluororesins are amorphous solvent type or fine particle dispersion type such as tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA). Among these, the above amorphous solvent type tetra The fluoroethylene / perfluoro (2,2-dimethyl-1,3-dioxole) copolymer prevents adhesion of the resin component of the molten resin mass to the compression molding member, and easily obtains uniformity of the coating layer. Preferably, it is applied by dipping or spraying.
The baking of the paint is different depending on the form of the paint, the type of resin, the type of solvent, etc., but generally, drying is performed at 100 ° C. to 150 ° C. for 10 minutes to 60 minutes, and the next baking is performed using a fluororesin. It is preferable to perform heating for 10 to 60 minutes in the range of melting point (Tm) or glass transition point (Tg) + 10 ° C. to decomposition start temperature (Tc) −10 ° C. The heating method is electric furnace heating, flame heating, hot air Heating, infrared heating, high-frequency heating, or the like can be used.
As a preferable application example of the above-described compression molding member, there is a preform manufacturing apparatus by compression molding shown in FIG. 2 described above, and a molten synthetic resin extruded from an extrusion nozzle of an extruder has a predetermined size. It is applied to at least one of the holding mechanism 22 provided with the holding members 30 and 32 for holding the molten resin mass cut into pieces, the throat 56 having the guide opening 64 or the inner surface of the female die 48.
The member for compression molding of a molten resin lump according to the present invention is effective for the above-described compression molding of a molten resin lump made of polyester resin and the compression member thereof, but is not limited thereto. Molten resin lump such as polyolefin, nylon, etc. The present invention can be applied to other molding fields that handle the material, and its use and application range are not limited.

[Evaluation of fluororesin coated mold (female)]
In a mold (female mold) for compressing a molten resin mass made of polyester resin into a preform for a bottle, the state of insertion into the mold (sliding property) and adhesion of the resin component to the inner surface of the mold after compression molding The condition, the surface property of the preform, and the gloss of the bottle appearance after biaxial stretch blow molding were evaluated.
[1] Insertion into mold (sliding property)
The insertion state when 12 hours passed after the start of compression molding was evaluated.
Evaluation method is
○: Insert smoothly into the mold (female).
X: Occasionally, entry into the mold (female mold) is delayed, and biting occurs by the male mold before complete entry.
XX: Entering into the mold (female) is slow and biting is frequent.
[2] Adhesion of resin component after compression molding of preform 12 hours after the start of compression molding, the mold was removed from the molding machine, and the amount of resin adhered to the inner surface of the mold was measured. The measurement method consists of immersing a mold in a 1: 1 solvent mixture of 1,1,1,3,3,3, -hexafluoro-2-propanol and chloroform to dissolve the adhered resin component, and gel permeation. Measured by the chromatography method (GPC method).
In the measurement, a predetermined weight of the resin used for molding was weighed and dissolved in a 1: 1 solvent mixture of 1,1,1,3,3,3-hexafluoro-2-propanol and chloroform. Dilution with a 1: 1 solvent mixture of 1,1,1,3,3,3-hexafluoro-2-propanol and chloroform to prepare a standard solution of a constant concentration series, and a calibration curve obtained from these standard solutions Was used to determine the amount of resin adhered to the inner surface of the mold.
[3] Surface properties of preforms 200 preforms were extracted every 2 hours from 2 hours to 12 hours after compression molding, and visually evaluated in the following three stages.
○: From 2 hours to 12 hours after compression molding, wrinkles and dullness (dullness) are not recognized or recognized somewhat, but the surface properties of the bottle after biaxial stretch blow molding are not affected.
X: From 2 hours to 12 hours after compression molding, wrinkles and fogging (dullness) sometimes occur, which affects the surface properties of the bottle after biaxial stretch blow molding.
XX: Wrinkles and dullness (dullness) occur continuously, affecting the surface properties of the bottle after biaxial stretch blow molding.
It was.
[4] Appearance gloss of polyester bottle 20 preforms are drawn out after 2 hours of compression molding, biaxially stretch blow molded, and haze value (cloudiness) of the bottle body with Suga Test Instruments Haze Meter HGM-2K ) And the following three stages of evaluation were performed.
○: Haze value (average value) less than 10% (good glossiness).
Δ: Haze value (average value) of 10 to less than 25% (gloss is slightly inferior but possible as a product).
X: Haze value (average value) 25% or more (inferior glossiness).

[1] Creation of a fluororesin coating mold (female mold) for compression molding a polyester resin preform Stainless steel (SUS-HPM38) was cut as the metal base of the mold, and the total height (L): 65 mm A fluororesin-coated mold for molding a preform having a blow-molded part height (M) of 53 mm and a blow-molded part thickness (T) of 3.5 mm was prepared.
Fine shots were sprayed on the surface of the inner surface of the mold that was in contact with the molten resin lump, and the average surface roughness (Ra JIS B 0601-1994) and 10-point average roughness (Rz JIS B 0601-1994) shown in Table 1 were sprayed. ) Was obtained.
[2] Formation of fluororesin coating layer The inner surface of the metal mold (female mold) made of the metal substrate is alkali-degritted and acid-washed, dried at 150 ° C. for 10 minutes, and subjected to electrolytic chromate treatment to obtain a metal oxide. A layer (intermediate layer) was formed.
Next, the above-mentioned gold is added to a solution prepared by dissolving an amorphous fluororesin [AF2400 / Mitsui DuPont Co., Ltd.] in a fluorinated solvent [FC77 / 3M Co.] so as to be 0.05% by weight. The mold was immersed and coated with fluororesin.
Thereafter, drying was performed at 150 ° C. for 30 minutes to volatilize the solvent, followed by baking at 320 ° C. for 30 minutes to form a fluororesin coating having an average film thickness of 0.01 μm on the inner surface of the mold.
[3] Preform molding The polyester molten resin mass extruded from the extruder was compression molded using the fluororesin-coated mold cooled to 20 ° C. to obtain a preform.
Then, after crystallizing the mouth part of this preform, it was heated to 110 ° C. above the glass transition temperature (Tg) and biaxially stretched in a blow mold to obtain a heat-resistant polyester bottle.
The blow molding conditions at this time were a mold temperature of 150 ° C., a pre-blow pressure of 1 to 1.7 MPa, a blow pressure of 3.5 MPa, and the bottle draw ratio was an average of 2.7 in the longitudinal direction and an average of 3.5 in the circumferential direction. went.

  The average surface roughness (Ra JIS B 0601-1994) and 10-point average roughness (Rz JIS B 0601-1994) of the surface in contact with the molten resin lump on the inner surface of the mold are the surface properties shown in Table 1, and are amorphous. Evaluation was performed in the same manner as in Example 1 except that the mold was immersed in a solution having a different fluororesin concentration to coat the fluororesin, and a fluororesin coating having an average film thickness of 0.2 μm was formed on the inner surface of the mold. Went.

  The average surface roughness (Ra JIS B 0601-1994) and 10-point average roughness (Rz JIS B 0601-1994) of the surface in contact with the molten resin lump on the inner surface of the mold are the surface properties shown in Table 1, and are amorphous. Example 1 except that the mold was immersed in a solution having a modified fluororesin concentration to coat the fluororesin, and a fluororesin coating having an average film thickness of 0.2 μm was formed on the inner surface of the mold. Evaluation was performed.

表１に示すように、本発明の溶融樹脂塊の圧縮成形用部材によれば、溶融樹脂塊を用いた圧縮成形による連続生産を長時間行っても、圧縮成形部材の表面に樹脂成分が付着して粘着性が増大することなく、長時間にわたる安定した連続生産、高能率生産が可能であった。
即ち、実施例は、圧縮成形金型への挿入状態において良好（○）、プリフォームの表面性状において良好（○）、ボトルの表面性状において良好（○）又はやや良好（△）であり優れた評価が得られたが、比較例は、いずれかの項目において不良（××）若しくはやや不良（×）であった。
尚、前記実施例及び比較例とは別に、フッ素樹脂被覆層を形成する金属基材の表面性状である平均表面粗さ（Ｒａ ＪＩＳ Ｂ ０６０１−１９９４）及び１０点平均粗さ（Ｒｚ ＪＩＳ Ｂ ０６０１−１９９４）の影響を後述する参考例に従って確認したので、その結果も表１に示す。
［参考例１］
金型内面の溶融樹脂塊と接触する面の平均表面粗さ（Ｒａ ＪＩＳ Ｂ ０６０１−１９９４）、１０点平均粗さ（Ｒｚ ＪＩＳ Ｂ ０６０１−１９９４）を表１に示す表面性状とした以外は、実施例１と同様に評価を行った。
［参考例２］
金型内面の溶融樹脂塊と接触する面の平均表面粗さ（Ｒａ ＪＩＳ Ｂ ０６０１−１９９４）、１０点平均粗さ（Ｒｚ ＪＩＳ Ｂ ０６０１−１９９４）を表１に示す表面性状とした以外は、実施例４と同様に評価を行った。The average surface roughness (Ra JIS B 0601-1994) and 10-point average roughness (Rz JIS B 0601-1994) of the surface in contact with the molten resin lump on the inner surface of the mold are the surface properties shown in Table 1, and are amorphous. Fluorine resin with an average film thickness of 0.25 μm on the inner surface of the mold without forming a metal oxide layer (intermediate layer) by immersing the mold in a solution having a modified fluororesin concentration The same evaluation as in Example 1 was performed except that a coating was formed.
[Comparative Example 1]
The same evaluation as in Example 1 was performed except that the metal oxide layer and the fluororesin coating layer were not formed on the inner surface of the mold.
[Comparative Example 2]
Example 3 except that the mold was immersed in a solution having a different concentration of amorphous fluororesin to coat the fluororesin, and a fluororesin coating having an average film thickness of 0.3 μm was formed on the inner surface of the mold. Evaluation was performed in the same manner.
[Comparative Example 3]
Example 4 is the same as Example 4 except that the mold was immersed in a solution having a different amorphous fluororesin concentration to coat the fluororesin, and a fluororesin coating having an average film thickness of 0.4 μm was formed on the inner surface of the mold. Evaluation was performed in the same manner.
Inserted state of polyester resin molten resin lump into mold (slipperiness) in Examples and Comparative Examples, adhesion state of resin component after compression molding of preform, surface property of preform and appearance gloss of polyester bottle The evaluation results are shown in Table 1.

As shown in Table 1, according to the member for compression molding of a molten resin lump of the present invention, the resin component adheres to the surface of the compression molded member even if continuous production by compression molding using the molten resin lump is performed for a long time. Thus, stable continuous production over a long period of time and high-efficiency production were possible without increasing the adhesiveness.
That is, the examples were excellent in the insertion state into the compression mold (◯), excellent in the surface property of the preform (◯), good in the surface property of the bottle (◯) or slightly good (Δ), and excellent. Although evaluation was obtained, the comparative example was a defect (xx) or some defect (x) in any item.
In addition, apart from the examples and comparative examples, the average surface roughness (Ra JIS B 0601-1994) and 10-point average roughness (Rz JIS B 0601), which are the surface properties of the metal base material forming the fluororesin coating layer, are used. -1994) was confirmed according to a reference example described later, and the results are also shown in Table 1.
[Reference Example 1]
Except that the average surface roughness (Ra JIS B 0601-1994) and 10-point average roughness (Rz JIS B 0601-1994) of the surface in contact with the molten resin lump on the inner surface of the mold are the surface properties shown in Table 1, Evaluation was performed in the same manner as in Example 1.
[Reference Example 2]
Except that the average surface roughness (Ra JIS B 0601-1994) and 10-point average roughness (Rz JIS B 0601-1994) of the surface in contact with the molten resin lump on the inner surface of the mold are the surface properties shown in Table 1, Evaluation was performed in the same manner as in Example 4.

  According to the member for compression molding of a molten resin lump of the present invention, in continuous production over a long time such as compression molding using the molten resin lump, the resin component adheres to the surface of the compression molded member that handles the molten resin lump. Therefore, stable production over a long period of time and high-efficiency production are possible without increasing the performance.

Claims (3)

The surface of the metal substrate is a rough surface, a fluororesin coating layer is formed on the surface of the metal substrate, and the fluororesin coating layer is a rough surface, and the coefficient of static friction between the molten resin mass and the surface of the fluororesin coating layer is 1. 7 or less ,
The rough surface of the metal substrate surface has an average surface roughness (Ra JIS B 0601-1994) of 0.1 to 3 μm and a 10-point average roughness (Rz JIS B 0601-1994) of 0.5 to 16 μm. ,
A member for compression molding of a molten resin mass, wherein the fluororesin coating layer has an average thickness of 0.01 to less than 0.3 μm . The member for compression molding of a molten resin lump according to claim 1 , wherein the metal substrate is made of aluminum, stainless steel, or steel. The compression of the molten resin lump according to claim 1 or 2 , wherein an intermediate layer composed of a metal oxide layer, a metal hydroxide layer, or a silane coupling layer is formed between the metal substrate and the fluororesin coating layer. Molding member.

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