JP5476251B2 - Thin-walled deep-drawn molded product and its manufacturing method - Google Patents

Description

  The present invention relates to a thin-walled deep-drawn molded article made of a resin composition containing polyphenylene sulfide (PPS) and a method for producing the same.

  PPS resin compositions containing PPS and inorganic fillers have excellent mechanical properties, heat resistance, chemical resistance, and electrical properties, so that they can be used as parts materials for automobiles, electrical / electronic parts, chemical equipment, etc. It is widely used.

  The PPS resin composition is usually formed by injection molding. In injection molding, molding and cooling are performed with a mold heated near the temperature-rising crystallization temperature (Tcc) to promote crystallization of PPS. Therefore, thin-walled products are deformed when injected from the mold. Therefore, it is impossible to obtain a thin-walled molded article with good dimensional accuracy.

  Patent Document 1 describes a continuous molding method of a tubular thin-walled molded product made of PPS by extrusion molding. However, it does not describe a method for producing a thin-walled deep-drawn molded product from a tubular thin-walled molded product.

According to claim 1 of Patent Document 2, a crystalline polyarylene sulfide resin or a composition thereof is melt-extruded and rapidly cooled to form a substantially amorphous sheet, and this sheet is at least a glass transition temperature (T) of the resin. _g ) Using a mold that has been preheated to a temperature not higher than the temperature-rising crystallization temperature (T _cc ) and then not lower than the temperature-rising crystallization temperature and below the melting point (T _m ) to 10 ° C., vacuum forming or A process for producing a crystalline polyarylene sulfide resin thin-walled molded product characterized by compression molding is described. In the examples, it is described that a cup-shaped molded product having a bottom diameter of 6 cm, a top diameter of 8 cm, and a height of 5 cm was thermoformed.
However, when formed into a deep-drawn product, the sheet cannot follow the elongation during vacuum forming and is cut off or a hole is formed, resulting in a molded product.

JP 2007-38485 A JP-A-5-269830

An object of the present invention is to provide a thin-walled deep-drawn molded article having good heat resistance and mechanical properties.
Another object of the present invention is to provide a method for manufacturing a thin-walled deep-drawn molded product that can obtain the thin-walled deep-drawn molded product with high dimensional accuracy.

As a means for solving the problems, the present invention
It is a thin-walled deep-drawn molded product formed of a resin composition containing polyphenylene sulfide (PPS), vacuum-formed or pressure-formed,
The PPS has a melt viscosity (measurement conditions: temperature 310 ° C., shear rate 1200 s ⁻¹ ) of 350 to 1000 Pa · s,
A thin-walled deep-drawn molded product that satisfies the following (a) to (d) is provided.
(A) The ratio of the bottom area to the opening area of the molded product is 0.7 or more. (B) The ratio (drawing ratio) of the depth of the molded product to the long side or the inner diameter of the opening shape of the molded product. The range of 0.8 or more (c) The ratio (t1 / t2) of the average thicknesses t1 and t2 at two different heights of the flat part (meaning excluding corners) of the molded product is 0.8 to 1. Range of 2 (d) PPS crystallinity is 23-33%

The present invention also provides a solution to other problems.
A method for producing a thin-walled deep-drawn product according to claim 1,
A step of obtaining a sheet comprising a resin composition containing polyphenylene sulfide (PPS) having a melt viscosity of 350 to 1000 Pa · s,
A step of pre-heat-treating the sheet obtained in the previous step while maintaining it in a temperature range from a temperature rising crystallization temperature (Tcc) + 50 ° C. to a melting point (Tm) −10 ° C.,
A step in which the preheated sheet is placed in a mold maintained in a temperature range from a temperature equal to or higher than a temperature-rising crystallization temperature (Tcc) to a melting point (Tm) −10 ° C., and then subjected to vacuum forming or pressure forming.
A method for producing a thin-walled deep-drawn molded product having

The thin-walled deep-drawn molded product of the present invention has high dimensional accuracy, no variation in thickness in one molded product, and no variation in thickness among many molded products.
Since the thin-walled deep-drawn molded product of the present invention contains PPS, it has good heat resistance, mechanical properties, chemical resistance, and electrical properties. By applying the production method of the present invention, the dimensions having the above properties are obtained. Various parts with high accuracy can be provided.

<Thin wall deep-drawn product>
The PPS contained in the resin composition used in the present invention may be a homopolymer or a copolymer. In the case of a homopolymer, a linear polymer is preferable.

  Examples of the copolymer include a copolymer of a structural unit containing a p-phenylene group and a structural unit containing another arylene group (preferably m-phenylene group). From the viewpoint of moldability, heat resistance, and mechanical properties. The proportion of structural units containing a p-phenylene group is preferably 60 mol% or more, more preferably 70 mol% or more. The copolymer may be a random bond or a block bond, but a block bond is preferred from the viewpoint of heat resistance and mechanical properties.

PPS (homopolymer or copolymer) has a melt viscosity (measurement conditions: temperature 310 ° C., shear rate 1200 s ⁻¹ ) of 350 to 1000 Pa · s, preferably 450 to 600 Pa · s.

If necessary, the resin composition used in the present invention can be blended with an amount and a kind of thermoplasticity within a range that can solve the problems of the present invention.
Such a thermoplastic resin preferably has a melting point lower than that of PPS, and is an olefin polymer or copolymer mainly composed of polyolefin such as polyethylene, polypropylene or a modified polymer thereof; nylon 6, nylon 66, other Polyamide polymer or copolymer; Polyester polymer or copolymer mainly composed of polyethylene terephthalate, polybutylene terephthalate, etc .; Liquid crystalline polyester polymer; Styrene polymer such as polystyrene, polyacrylonitrile, ABS; Polyalkyl acrylate And acrylic polymers such as polycarbonate, polyphenylene oxide, polyacetal and the like. Two or more of these thermoplastic resins can be used.

  The resin composition used in the present invention may contain one or more selected from granular, fibrous or flaky (plate-like) fillers depending on the properties required for the thin molded article. it can.

  Examples of the fibrous filler include glass fiber, carbon fiber, silica fiber, silica / alumina fiber, zirconium fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum, titanium, copper, Examples thereof include fibers such as brass, and among these, glass fibers and carbon fibers are preferable.

  The fibrous filler preferably has an average fiber length of 1 to 800 μm, more preferably 5 to 600 μm. When the product within the above range is used, the dimensional stability of the thin molded product is improved and the appearance is also improved. The average fiber length is determined by a counting method (a method of observing with a scanning electron microscope and measuring the size of the filler).

  As granular fillers, carbon black, graphite, silica, quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, silicates such as wollastonite, iron oxide, titanium oxide Metal oxides such as alumina, metal carbonates such as calcium carbonate and magnesium carbonate, metal sulfates such as calcium sulfate and barium sulfate, silicon carbide, silicon nitride, boron nitride, various metal powders Etc.

  The granular filler preferably has an average particle diameter of 1 to 800 μm, more preferably 5 to 600 μm. When the product within the above range is used, the dimensional stability of the thin molded product is improved and the appearance is also improved. The average particle diameter is determined by a counting method (a method of observing with a scanning electron microscope and measuring the size of the filler).

  Examples of the flaky filler include mica, glass flakes and various metal foils.

  The flaky filler preferably has an average maximum length of 1 to 800 μm, more preferably 5 to 600 μm. When the product within the above range is used, the dimensional stability of the thin molded product is improved and the appearance is also improved. The average maximum length is obtained by a counting method (a method of observing with a scanning electron microscope and measuring the size of the filler).

  As necessary, these fillers may be prepared by adhering hypophosphorous acid or a salt thereof to the surface, or may be converged by using a sizing agent. Compounds, isocyanate compounds, silane compounds, titanate compounds) that have been surface-treated may be used.

  1-200 mass parts is preferable with respect to 100 mass parts of PPS, as for the compounding quantity of these fillers, 5-100 mass parts is more preferable, and 10-50 mass parts is still more preferable.

  In addition to the filler, an organic filler can be supplementarily blended as necessary. As the organic filler, a high melting point fibrous or powdery polymer such as fluororesin and aromatic polyamide can be used.

  In addition, various additives such as pigments, ultraviolet absorbers, antioxidants, thermal stabilizers, lubricants, flame retardants, release agents, and other known additives are used for the resin composition depending on the use of the thin-walled deep-drawn molded product. Additives can be blended.

The thin-walled deep-drawn molded product of the present invention is formed by vacuum forming or pressure forming, and satisfies the following (a) to (d).
(A) The bottom area (bottom area / opening area) with respect to the opening area of the molded product is 0.7 or more, and 0.8 to 1.0 is preferable in the present invention.
(B) Ratio of the depth of the molded product to the long side or inner diameter of the opening shape of the molded product (depth of the molded product / long side or inner diameter of the opening shape of the molded product) (drawing ratio) is 0.8. In the present invention, 0.8 to 1.1 is preferable.
(C) The ratio (t1 / t2) of the average thicknesses t1 and t2 at two different heights of the flat part (meaning excluding the corners) of the molded product is 0.8 to 1.2, preferably 0.9-1.1.
The two different heights are a height position of 33% of the total height and a height position of 67%. In the embodiment, the height is 10 mm and 20 mm from the bottom surface.
(D) The crystallinity of PPS is 23 to 33%.

<Manufacturing method of thin-walled deep-drawn product>
In the first step, a sheet made of a resin composition containing PPS having a melt viscosity of 350 to 1000 Pa · s (preferably 450 to 600 Pa · s) is obtained.

  In this step, a sheet can be obtained by applying a known method (for example, a method described in Examples of Patent Document 2). The obtained sheet may be crystallized or may not be crystallized.

  In the next step, the temperature obtained from the temperature rising crystallization temperature (Tcc) + 50 ° C. to the melting point (Tm) −10 ° C. with respect to the sheet obtained in the previous step by a forming machine (vacuum forming machine or pressure forming machine). Pre-heat treatment is performed while maintaining the temperature range, preferably the temperature rising crystallization temperature (Tcc) + 100 ° C. to the melting point (Tm) −20 ° C. The preheating time is the time until the sheet reaches the above temperature range.

  When the preheating temperature is equal to or higher than the lower limit value, a deep-drawn molded product can be obtained with high dimensional accuracy, and when the preheating temperature is equal to or lower than the upper limit value, drawdown during molding can be prevented.

  In the next step, the sheet pre-heated in the previous step is placed in a mold maintained in a temperature range from a temperature higher than the crystallization temperature (Tcc) to the melting point (Tm) -10 ° C., and then vacuum forming or compressed air Mold. The temperature range is preferably a temperature range from a temperature rising crystallization temperature (Tcc) + 5 ° C. to a melting point (Tm) −20 ° C.

  When the mold temperature is equal to or higher than the lower limit value, a deep-drawn molded product can be obtained with high dimensional accuracy, and when the mold temperature is equal to or lower than the upper limit value, PPS is crystallized to a crystallinity within a predetermined range, The heat resistance and mechanical properties of the molded product can be improved.

  In this step, the sheet pre-heated in the previous step is molded with a mold maintained at a temperature lower than the temperature rising crystallization temperature (Tcc), and then heated again to the temperature higher than the temperature rising crystallization temperature (Tcc). A method of crystallization can also be applied.

(1) Melt viscosity Measured using a capillograph manufactured by Toyo Seiki at a temperature of 310 ° C. and a shear rate of 1200 s ⁻¹ .

(2) Temperature measurement Conforms to JIS K-7121. The glass transition temperature (Tg), temperature rising crystallization temperature (Tcc), and melting point (Tm) of PPS are the calorimetric curve when the temperature is raised at a rate of 20 ° C./min using a differential scanning calorimeter (DSC). It calculated | required from the inflection point or the exothermic peak.

(3) Sheet formability Sheet formability by an extruder was evaluated according to the following criteria.
○: Resin pressure is appropriate during molding (5Mpa or less)
Δ: Resin pressure is slightly high during molding (7Mpa or less)
X: Resin pressure is high during molding (15Mpa or more)

(4) Sheet appearance The molded sheet appearance was observed with the naked eye and evaluated according to the following criteria.
○: The flow mark is inconspicuous. Appearance is good.
Δ: The flow mark is visible, but there are no large irregularities.
X: A flow mark is conspicuous. Appearance is bad.

(5) Formability The case where the sheet stretches according to the shape of the mold was considered good.

(6) Dimensional accuracy At the depth position of 10 mm from the bottom surface, the thickness of four points was measured at equal intervals on the circumference, and the average thickness (t1) was obtained.
Similarly, the thickness of four points was measured at equal intervals on the circumference at a depth of 20 mm from the bottom, and the average thickness (t2) was obtained. When t1 / t2 is calculated, the closer the ratio is to 1.0, the better the dimensional accuracy.
In addition, the dimension of the molded article was measured using a micrometer, a caliper, and an R gauge.

(7) Crystallinity Calculated by specific gravity method.

Examples 1-5, Comparative Examples 1-4
(Sheet forming process)
Melting extrusion of PPS (manufactured by Polyplastics Co., Ltd.) shown in Table 1 using a VS40-25 extruder (screw diameter 40 mm) made by Ikegai with a coat hanger die (T die: lip 300 mm width). did.
After the extrusion, the sheet was cooled with a cooling roll having an outer diameter of 200 mm (roll temperature 150 ° C.) to obtain a sheet having a thickness of 0.6 mm.

(Preheating process)
In a vacuum forming machine (vacuum pressure air forming machine FK-0431-10 manufactured by Asano Laboratory), the sheet (250 mm × 250 mm) was preheated until the temperature shown in Table 1 was reached.

(Molding process)
As a mold for vacuum forming, a bottomed cylindrical mold (female mold) (inner diameter 30 mm x depth 30 mm, bottom has R3 mm roundness; has 8 vacuum suction holes at the bottom) Using.
The preheated sheet is moved onto the mold, and is pushed into the mold maintained at a predetermined temperature with a cylindrical plug having a convex portion (inner diameter 26 mm, bottom surface has a rounded R3 mm), and sucked in the mold. A cup-shaped thin deep-drawn molded product (opening inner diameter 30 mm, bottom inner diameter 30 mm, depth 30 mm) was obtained. The molding pressure was 200 kPa, the plug temperature was 150 ° C., and the cooling time after molding was 15 to 60 seconds.

Comparative Example 5
(Sheet forming process and preheating process)
Melt extrusion was carried out in the same manner as in Examples 1 to 5 to obtain a sheet having a thickness of 0.6 mm. Then, it preheated similarly to Examples 1-5.

(Molding process)
As a mold for vacuum forming, a bottomed cylindrical mold (female mold) (inner diameter 30 mm x depth 15 mm, bottom surface has rounded R3 mm; has 8 vacuum suction holes at the bottom) Using. (As a comparative example, a non-deep die was used.)
The preheated sheet is moved onto the mold, and is pushed into the mold maintained at a predetermined temperature with a cylindrical plug having a convex portion (inner diameter 26 mm, bottom surface has a rounded R3 mm), and sucked in the mold. A cup-shaped thin-walled deep-drawn molded product (opening inner diameter 30 mm, bottom inner diameter 30 mm, depth 15 mm) was obtained. The molding pressure was 200 kPa, the plug temperature was 150 ° C., and the cooling time after molding was 60 seconds.

Comparative Example 6
(Sheet forming process and preheating process)
Melt extrusion was carried out in the same manner as in Examples 1 to 5 to obtain a sheet having a thickness of 0.6 mm. Then, it preheated similarly to Examples 1-5.

実施例１〜５から明らかなとおり、本発明の薄肉深絞り成形品は、寸法精度が高く、厚みのばらつきもなかった。
比較例４〜６から明らかなとおり、シートの予熱温度が低いと、本発明の要件（ａ）、（ｂ）を満たさない、深絞りではない薄肉成形品は成形できたが（比較例５、６）、本発明の要件（ａ）、（ｂ）を満たす深絞り成形品は成形できなかった（比較例４）。 As a mold for vacuum forming, a bottomed cylindrical mold (female) (opening inner diameter 30mm, bottom inner diameter 21mm x depth 30mm, bottom has R3mm roundness; 8 vacuum suction holes at the bottom Have). (As a comparative example, a non-deep die was used.)
Move the preheated sheet onto the mold and push it into the mold maintained at the specified temperature with a truncated cone-shaped plug (with an inner diameter of 26mm to 17mm and a bottom of R3mm rounded). To obtain a cup-shaped thin-walled deep-drawn molded product (opening inner diameter 30 mm, bottom inner diameter 21 mm, depth 30 mm). The molding pressure was 200 kPa, the plug temperature was 150 ° C., and the cooling time after molding was 60 seconds.

As is clear from Examples 1 to 5, the thin-walled deep-drawn molded product of the present invention had high dimensional accuracy and no variation in thickness.
As is clear from Comparative Examples 4 to 6, when the preheating temperature of the sheet was low, a thin molded article that did not satisfy the requirements (a) and (b) of the present invention and was not deep drawn could be molded (Comparative Example 5, 6) A deep-drawn molded product satisfying the requirements (a) and (b) of the present invention could not be molded (Comparative Example 4).

Claims (4)

It is a thin-walled deep-drawn molded product formed of a resin composition containing polyphenylene sulfide (PPS), vacuum-formed or pressure-formed,
The PPS has a melt viscosity (measurement conditions: temperature 310 ° C., shear rate 1200 s ⁻¹ ) of 350 to 1000 Pa · s,
A thin-walled deep-drawn molded product that satisfies the following (a) to (d).
(A) The ratio of the bottom area to the opening area of the molded product is 0.7 or more. (B) The ratio (drawing ratio) of the depth of the molded product to the long side or the inner diameter of the opening shape of the molded product. The range of 0.8 or more (c) The ratio (t1 / t2) of the average thicknesses t1 and t2 at two different heights of the flat part (meaning excluding corners) of the molded product is 0.8 to 1. Range of 2 (d) PPS crystallinity is 23-33% The thin-walled deep-drawn molded article according to claim 1, wherein the PPS has a melt viscosity (measurement conditions: temperature 310 ° C., shear rate 1200 s ⁻¹ ) of 450 to 600 Pa · s. A method for producing a thin-walled deep-drawn product according to claim 1,
A step of obtaining a sheet comprising a resin composition containing polyphenylene sulfide (PPS) having a melt viscosity of 350 to 1000 Pa · s,
A step of pre-heat-treating the sheet obtained in the previous step while maintaining it in a temperature range from a temperature rising crystallization temperature (Tcc) + 50 ° C. to a melting point (Tm) −10 ° C.,
A step in which the preheated sheet is placed in a mold maintained in a temperature range from a temperature equal to or higher than a temperature-rising crystallization temperature (Tcc) to a melting point (Tm) −10 ° C., and then subjected to vacuum forming or pressure forming.
A method for producing a thin-walled deep-drawn molded product having PPS used in the step of obtaining the sheet has a melt viscosity of 450 to 600 Pa · s,
The thin-walled deep-drawn molded product according to claim 3, wherein a mold temperature in the vacuum forming or pressure forming step is a temperature range from a temperature rising crystallization temperature (Tcc) + 5 ° C or higher to a melting point (Tm) -20 ° C. Manufacturing method.