JP4438148B2 - Production method of foamed propeller fan - Google Patents

Description

【００３５】
【発明の効果】
本発明の発泡プロペラファンの製造方法は、特定形状の金型を用い、特定の射出成形法と特定の射出成形条件によって、翼部の剛性、軽量性に優れる上、かつ翼形状が良好で、低騒音性にも優れる発泡プロペラファンが得られるものである。このため、高回転にも耐えることができ、高風量を得ることが可能である。また、軽量性に優れることから、材料コストが安く済むばかりか、モーターの消費電力も低く抑えることが可能である。
【図面の簡単な説明】
【図１】 本発明の製造方法で得られる発泡プロペラファンの1例を示す（平面図）。
【図２】 本発明の製造方法で得られる発泡プロペラファンの1例を示す（側面図）。
【図３】 本発明の良好な翼形状の1例を示す（断面図）。
【図４】 本発明範囲外の翼形状の1例を示す（断面図）。
【図５】 本発明範囲外の翼形状の1例を示す（断面図）。
【図６】 本発明の容積拡大前の翼形状の1例を示す（断面図）。
【符号の説明】
1…ハブ
2…翼部
3…翼部外周
4…翼部付根
5…翼部先端
6…発泡部分
7…非発泡部分
8…段差
9…くさび状凹部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a foamed propeller fan made of a thermoplastic resin, which is widely used for automobiles, air conditioners and the like for the purpose of blowing, cooling, exhaust and the like. Specifically, it is obtained by combining a mold with a specific shape with a specific injection molding method and injection molding conditions, and has a foam structure in the wing, and has a good wing shape, rigidity, light weight, and low noise. The present invention relates to a method for producing a foamed propeller fan having excellent properties.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, attempts have been made to increase the rigidity of a propeller fan made of a thermoplastic resin by increasing the thickness of a blade to increase the air flow and noise. However, increasing the thickness of the propeller fan increases the weight of the propeller fan, increasing the material cost and increasing the power consumption of the motor.
[0003]
For this reason, attempts have been already made to reduce the thickness and weight of resin propeller fans by a short shot foam molding method or a gas injection molding method.
The short shot foam molding method is to inject a foamable resin composition in an amount smaller than the volume of the cavity (so-called short shot) and fill the cavity by using the increase in volume due to foaming of the composition. In Japanese Patent Laid-Open No. 10-89298, etc., a foamed propeller fan by a short shot foam molding method has been proposed. According to this method, it is possible to obtain a propeller fan having an ideal blade shape and a reduced weight, but the expansion ratio is about 1.6 to 1.7 times at most, which is still unsatisfactory in terms of weight reduction. In addition, the problem was that the rigidity of the wings was slightly insufficient due to the foamed structure.
A propeller fan using a gas injection molding method is proposed in Japanese Patent Laid-Open No. 9-112491. Even with this method, it is possible to obtain a propeller fan that has an ideal blade shape and is lightweight, but there is a large variation in the weight of each blade, and the dynamic balance deteriorates so that it cannot withstand high rotation. Or, there was a problem that noise was generated as the dynamic balance deteriorated.
A method for obtaining a propeller fan by hollowing the wing portion as an upper and lower bonded structure has also been proposed in Japanese Patent Laid-Open No. 61-108898. Although this method has a large weight reduction effect and small weight variation, the bonding process is complicated and the productivity is remarkably deteriorated, and the problems such as deformation at the time of bonding and peeling of the bonded part are unfavorable in terms of quality. was there.
On the other hand, Japanese Patent Application Laid-Open No. 9-277335 proposes a special mold opening foam molding method using a long fiber reinforced thermoplastic resin. By using this method, it is possible to obtain a molded article that is excellent in light weight and excellent in strength and rigidity by forming a surface solidified layer. However, when this method is applied to a fan, there is a problem that the blade shape deteriorates and noise is generated.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing a foamed propeller fan that eliminates all the above disadvantages, is thick and lightweight, is excellent in rigidity, has a good wing shape, and is excellent in low noise.
[0005]
[Means for Solving the Problems]
As a result of intensive studies to obtain a foamed propeller fan that has solved the above disadvantages, the present inventors have plasticized the foamable resin composition and injected and filled it into a mold cavity of a specific shape for a specific time, and cooled for a specific time. After that, the inventors have found that a foamed propeller fan obtained by an injection molding method in which the volume of the cavity is enlarged and a foamed layer is formed inside is extremely useful for solving the above problems, and the present invention has been achieved. .
[0006]
  That is, this invention consists of a structure shown below.
(1) Foam containing 95-99.9% by weight of thermoplastic resin and 0.1-5% by weight of chemical foaming agent, based on compositionSex treeA step of plasticizing the fat composition (a), a step of injecting the plasticized product into a closed mold cavity smaller than the volume of the target molded product (b), and contacting the mold surface after completion of injection filling Cooling to a state where the solidified layer to be mixed and the molten layer inside are mixed (c), expanding the volume of the cavity to the volume of the target molded product by opening the mold (d), and further cooling A foamed propeller fan having a foamed structure at least on the wing part, obtained through the step (e) of taking out the molded product after being performed, with respect to the wing part as the mold, the thickness of the minimum thickness part is 1 mm or more, Using a mold with a maximum thickness of 15 mm or less and a substantially arc-shaped outer periphery, b process time is 5 seconds or less, and c process time is defined by the following formula T_min~ T_maxThe manufacturing method of the foaming propeller fan characterized by making it in the range of these.
  T_min= H_max ²× (M / 1000)… Formula 1
    T_min : Minimum primary cooling time [sec]
    h_max : Maximum thickness of wings before mold opening [mm]
    M: Mold temperature [℃]
  T_max= H_min ²× (M / 30)… Formula 2
    T_max : Maximum primary cooling time [sec]
    h_min : Minimum thickness of wings before mold opening [mm]
    M: Mold temperature [℃]
  T_min≦ T_max                        ... Formula 3
(2)Step (a) of plasticizing a foamable resin composition containing 95 to 99.9% by weight of a thermoplastic resin and 0.1 to 5% by weight of a chemical foaming agent on the basis of the composition, a portion excluding the root and outer periphery of the wing A step (b) of injecting the plasticized material into a closed mold cavity smaller than the volume of the target molded product, and a mixture of a solidified layer contacting the mold surface after completion of injection filling and an internal molten layer Cooling to a state (c),The process of expanding the volume of the cavity to the volume of the target molded product by opening the mold of the part excluding the root of the wing and the outer periphery(d) a foamed propeller fan having a foamed structure at least on the wing part, which is obtained through the step (e) of taking out the molded product after further cooling, wherein the minimum thickness part is related to the wing part as the mold Using a mold with a wall thickness of 1 mm or more, a maximum wall thickness of 15 mm or less, and an outer periphery having a substantially arcuate end, and the time of step b is 5 seconds or less, andcProcess timeTheT defined by the following formula_min~ T_maxWithinIt is characterized byA method for producing a foamed propeller fan.
  T_min= H '_max ²× (M / 1000)… Formula 1
    T_min : Minimum primary cooling time [sec]
    h '_max : Maximum thickness of the volume expansion part [mm]
    M: Mold temperature [℃]
  T_max= H '_min ²× (M / 40)… Formula 4
    T_max : Maximum primary cooling time [sec]
    h '_min : Minimum wall thickness [mm]
    M: Mold temperature [℃]
  T_min≦ T_max                        ... Formula 3
(3) Expandable resin composition containing 35-94.9 wt% thermoplastic resin, 0.1-5 wt% chemical foaming agent, and 5-60 wt% inorganic filler on composition basis The method for producing a foamed propeller fan according to the above item 1 or 2.
(4) The method for producing a foamed propeller fan according to the above item 3, wherein the inorganic filler is a long glass fiber having a length of 2 to 50 mm.
(5) The manufacturing method of the foaming propeller fan of the said 3rd term | claim whose inorganic filler is a mixture of glass fiber and a plate-shaped inorganic filler.
(6) Foam containing 40 to 95% by weight of a thermoplastic resin and 5 to 60% by weight of a glass fiber having a length of 2 to 50 mm based on the composition.Sex treeStep (a) of plasticizing the fat composition, step (b) of injecting the plasticized product into a closed mold cavity smaller than the volume of the target molded article, and contacting the mold surface after completion of injection filling (C) cooling to a state where the solidified layer to be melted and the molten layer inside are mixed (c), expanding the volume of the cavity to the volume of the target molded product by opening the mold (d), and further cooling A foamed propeller fan having a foamed structure at least on the wing part, obtained through the step (e) of taking out the molded product after being performed, wherein the thickness of the minimum thickness part is 1 mm or more with respect to the wing part as the mold, Using a mold with a maximum thickness of 15 mm or less and a substantially arc-shaped outer periphery, b process time is 5 seconds or less, and c process time is defined by the following formula T_min~ T_maxThe manufacturing method of the foaming propeller fan characterized by making it in the range of these.
  T_min= H_max ²× (M / 1000)… Formula 1
    T_min : Minimum primary cooling time [sec]
    h_max : Maximum thickness of wings before mold opening [mm]
    M: Mold temperature [℃]
  T_max= H_min ²× (M / 30)… Formula 2
    T_max : Maximum primary cooling time [sec]
    h_min : Minimum thickness of wings before mold opening [mm]
    M: Mold temperature [℃]
  T_min≦ T_max                        ... Formula 3
(7)A step (a) of plasticizing a foamable resin composition containing 40 to 95% by weight of a thermoplastic resin and 5 to 60% by weight of a glass fiber having a length of 2 to 50 mm based on the composition, And a step (b) of injecting the plasticized product into a closed mold cavity smaller than the volume of the target molded article except for the outer periphery, and a solidified layer that comes into contact with the mold surface after completion of injection filling Step (c) of cooling to a state in which the internal molten layer is mixed,The process of expanding the volume of the cavity to the volume of the target molded product by opening the mold of the part excluding the root of the wing and the outer periphery(d) a foamed propeller fan having a foamed structure at least on the wing portion, obtained through the step (e) of taking out the molded product after further cooling, wherein the minimum thickness portion is related to the wing portion as the mold Using a mold with a wall thickness of 1 mm or more, a maximum wall thickness of 15 mm or less, and an outer periphery having a substantially arcuate end, and the time of step b is 5 seconds or less, andc Process time is defined as T_min~ T_maxWithinIt is characterized byA method for producing a foamed propeller fan.
  T_min= H '_max ²× (M / 1000)… Formula 1
    T_min : Minimum primary cooling time [sec]
    h '_max : Maximum thickness of the volume expansion part [mm]
    M: Mold temperature [℃]
  T_max= H '_min ²× (M / 40)… Formula 4
    T_max : Maximum primary cooling time [sec]
    h '_min : Minimum wall thickness [mm]
    M: Mold temperature [℃]
  T_min≦ T_max                        ... Formula 3
(8) Foaming in which the foamable resin composition contains, based on the composition, 40 to 95% by weight of a thermoplastic resin and 5 to 60% by weight of a mixture of long glass fibers having a length of 2 to 50 mm and a plate-like inorganic filler. 8. A method for producing a foamed propeller fan according to item 6 or 7, which is an adhesive resin composition.
(9) The method for producing a foamed propeller fan according to any one of items 1 to 8, wherein the thermoplastic resin is a polyolefin-based resin.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The thermoplastic resin used in the foamable resin composition of the present invention is not particularly limited. Specific examples include polyolefin resins such as polypropylene and polyethylene, polyamide resins such as 6 nylon and 66 nylon, polyethylene terephthalate, and polybutylene. Examples thereof include polyester resins such as terephthalate, polystyrene resins, AS resins, ABS resins, polycarbonate resins, methacrylic resins, and polyvinyl chloride resins.
Among the above thermoplastic resins, polyolefin resins are preferable from the viewpoints of easy handling and price. Polyolefin-based resins are ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, etc. This is a concept including a crystalline homopolymer of olefin, a crystalline copolymer comprising two or more of these α-olefins, or a composition comprising two or more of these polymers. Of these, polypropylene or a crystalline copolymer of propylene having a propylene content of 70% by weight or more and another α-olefin is practically preferred.
[0008]
In addition, when these polyolefin resins are used and a reinforcing material such as glass fiber is blended as described later, an unsaturated carboxylic acid or an anhydride thereof is grafted to the polyolefin resin from the viewpoint of the reinforcing effect. It is preferable to use a modified polyolefin resin or a mixture of a polyolefin-based resin and this modified polyolefin resin.
[0009]
If necessary, the foamable resin composition of the present invention may contain an antioxidant, a weathering agent (light stabilizer), an ultraviolet absorber, an antistatic agent, and a colorant. Furthermore, it is preferable to mix | blend inorganic fillers, such as glass fiber and mica, from a viewpoint of the rigidity and intensity | strength of a wing | blade part and the cylindrical part to which the wing | blade is attached, what is called a hub part.
[0010]
The inorganic filler used in the foamable resin composition of the present invention is not particularly limited. Specific examples include talc, mica, clay, calcium carbonate, aluminum hydroxide, magnesium hydroxide, barium sulfate, glass fiber, carbon fiber, silica, calcium silicate, potassium titanate, wollastonite and the like. Or may be used in combination. From the viewpoint of the reinforcing effect and cost, talc, mica, and glass fiber are preferably used. Moreover, it is also a preferable aspect to use glass fiber and mica in combination for the purpose of improvement in strength and prevention of warping and twisting.
The blending amount of the inorganic filler is preferably 5 to 60% by weight in the foamable resin composition. More preferably, it is 10 to 50% by weight. In addition, when using glass fibers (including short glass fibers with a length of less than 2 mm and long glass fibers with a length of 2 to 50 mm) in combination with plate-like inorganic fillers such as talc and mica, the blending amount is foamable. In the resin composition, each compounding amount of the glass fiber and the plate-like inorganic filler is in the range of 5 to 40% by weight, and the compounding amount of the mixture of the glass fiber and the plate-like inorganic filler is 10 to 60% by weight. It is preferable to adjust and mix. These inorganic fillers can be blended by melt kneading with a thermoplastic resin using an extruder, except for the case of the above-mentioned long glass fibers. A masterbatch having a higher blending amount than the desired blending amount may be prepared, and dry blend dilution may be performed to obtain the above blending amount.
[0011]
In addition, it is also possible to use a so-called long glass fiber reinforced thermoplastic resin that has been impregnated into a continuous glass roving with a molten thermoplastic resin and then pelletized to a length of 2 to 50 mm. Owing to the phenomenon that the long glass fiber sometimes repels and swells (so-called spring back), it is also preferable from the viewpoint that uniform foaming can be achieved particularly at a high expansion ratio.
[0012]
As a method for impregnating the reinforcing fiber bundle with the molten resin, any known method can be adopted as long as good impregnation property can be obtained. A method in which a reinforcing fiber bundle is impregnated with molten resin by passing the reinforcing fiber bundle over the surface of the spreader under tension (Japanese Patent Publication No. 63-37694), and a pair of open pins provided in the impregnation die with the reinforcing fiber bundle Any method can be employed such as impregnation by passing between them in a non-contact manner (International Publication WO97 / 19805), but the latter method is preferred in that there are few problems of fluff generation during high-speed take-up. It is.
The blending amount of the long glass fiber is preferably 5 to 60% by weight in the foamable resin composition. More preferably, it is 10 to 45% by weight. A masterbatch having a higher blending amount than the desired blending amount may be prepared, and dry blend dilution may be performed to obtain the above blending amount. After the dry blend dilution, it is preferable not to pass through the extruder but directly to the injection molding machine in order to maintain the fiber length.
[0013]
Examples of the chemical foaming agent used in the present invention include inorganic compounds such as ammonium carbonate and sodium bicarbonate, and organic compounds such as azo compounds, sulfonyl hydrazide compounds, nitroso compounds, and azide compounds.
Examples of the azo compound include azodicarbonamide (ADCA), azobisisobutyronitrile (AIBN), azohexahydrobenzonitrile, diazoaminobenzene, and the like. Examples of the sulfonyl hydrazide compound include benzenesulfonyl hydrazide, p-toluenesulfonyl hydrazide (TSH), benzene-1,3-disulfonyl hydrazide, diphenylsulfone-4,4′-disulfonylhydrazide, diphenyloxide-4,4′-di And sulfonyl hydrazide (OBSH). Examples of the nitroso compound include N, N′-dinitrosopentamethylenetetramine (DPT), N, N′-dimethyl-N, N′-dinitrosotephthalamide and the like. Examples of the azide compound include terephthalazide and p-tert-butylbenzazide.
[0014]
The method of addition is preferably a method in which the foaming agent is dry blended with the thermoplastic resin using a tumbler or the like. The foaming agent may be added as it is, or after adding a high concentration to the thermoplastic resin under a temperature condition in which the foaming agent does not foam and making a masterbatch, heat the masterbatch to a desired foaming agent amount. It can also be added to a plastic resin.
The foaming agent is preferably blended in the foamable resin composition of the present invention in an amount of 0.1 to 5% by weight, desirably 0.5 to 5% by weight. If the addition amount of the chemical foaming agent is too small, it is difficult to mold a molded product having a large expansion ratio. On the other hand, when the amount is too large, the foaming pressure becomes excessive, which tends to generate coarse bubbles, and discoloration of the molded product due to the decomposition residue of the chemical foaming agent occurs. However, in the case of a composition containing the above-mentioned long glass fiber and having a self-expanding property in a molten state, the composition is not limited to this, and a chemical foaming agent may not be blended.
[0015]
  The production method of the foamed propeller fan of the present inventionSex treeA step of plasticizing the fat composition (a), a step of injecting the plasticized product into a closed mold cavity smaller than the volume of the target molded product for a specific time (b), a step of cooling for a specific time ( c) Opening the mold and expanding the volume of the cavity to the target molded product volume (d), and further cooling and removing the molded product (e).
[0016]
The foamed propeller fan obtained by the production method of the present invention is not particularly limited as long as it is a propeller-shaped fan, but in order to obtain a good blade shape after foaming, the mold structure of the wing part of the mold to be used, The minimum wall thickness is 1mm or more, preferably 1.5mm or more, the maximum wall thickness is 15mm or less, preferably 10mm or less, and the outer periphery of the wing part (Fig. 1) is substantially circular when viewed in cross section. It is preferably an arcuate end (FIG. 6). Further, as the mold structure, a shape that causes deformation of the molded product when the mold is opened, that is, a so-called undercut shape is not preferable. This is because although the surface is solidified, the mold is opened while the inside is in a molten state, so that the molded product is easily damaged. Further, the hub portion may be foamed or not.
The expansion ratio is preferably 1.3 to 6 times the volume of the portion where the volume is expanded. More preferably, it is 2 to 4 times. If it is less than 1.3 times, the effect of weight reduction becomes small. Conversely, if it exceeds 6 times, uniform foaming becomes impossible and noise increases, which is not preferable.
[0017]
  The time required for the step b, that is, the time required for injection (hereinafter sometimes referred to as injection time) is 5 seconds or less, preferably 1 to 3.5 seconds, for the purpose of obtaining a good wing shape after foaming. So-called foaming at high speedSex treeIt is preferable to inject a plasticized product of the fat composition.
  Also, the c process time, that is, the cooling time until the solidified layer in contact with the mold surface and the internal molten layer coexist, is also defined by the following formula for the purpose of obtaining a good blade shape after foaming._min~ T_maxPreferably it is seconds. T_minIf it is less than this, since the thickness of the surface solidified layer becomes thin, it tends to burst during foaming. Conversely, T_maxIf it exceeds, solidification proceeds too much and the wing shape deteriorates. T_min> T_max However, since there is too much difference between the thickness of the minimum thickness part and the maximum thickness part of the wing part, the surface solidified layer of the thick part tends to burst during foaming. During the step c, so-called holding pressure, which is performed in a normal injection molding method, is not necessary, but holding pressure can be applied in a range where there is no particular problem in the next cavity volume expansion step.
  T_min= H_max ²× (M / 1000)… Formula 1
    T_min : Minimum primary cooling time [sec]
    h_max : Maximum thickness of wings before mold opening [mm]
    M: Mold temperature [℃]
  T_max= H_min ²× (M / 30)… Formula 2
    T_max : Maximum primary cooling time [sec]
    h_min : Minimum thickness of wings before mold opening [mm]
    M: Mold temperature [℃]
  T_min≦ T_max                        ... Formula 3
[0018]
Another mold structure for obtaining a good wing shape is one that expands the volume of the wing, excluding the root and outer circumference (Fig. 1). Since the root and the outer periphery do not foam, it is possible to avoid deterioration of the shape of the wing portion. In order to smooth the boundary between the volume expansion part and the non-expansion part, regarding the part where the volume is expanded, the minimum wall thickness before volume expansion is 1 mm or more, preferably 1.5 mm or more and the maximum wall thickness. The wall thickness is 15 mm or less, preferably 10 mm or less.
[0019]
  The b process time, that is, the injection time, is preferably 5 seconds or less, and preferably 1 to 3.5 seconds for the purpose of smoothing the boundary between the volume expansion portion and the non-expansion portion. So-called foaming at high speedSex treeIt is preferable to inject a plasticized product of the fat composition.
  In addition, the c process time, that is, the cooling time until the solidified layer contacting the mold surface and the internal molten layer coexist, is also expressed by the following formula for the purpose of smoothing the boundary between the volume expansion part and the non-expansion part. T defined by_min~ T_maxPreferably it is seconds. T_minIf it is less than this, since the thickness of the surface solidified layer becomes thin, it tends to burst during foaming. Conversely, T_maxIf it exceeds, solidification proceeds too much and the wing shape deteriorates. T_min> T_max However, since there is too much difference between the thickness of the minimum thickness portion and the maximum thickness portion of the wing portion, the surface solidified layer of the thick portion is easily ruptured during foaming. During the step c, so-called holding pressure, which is performed in a normal injection molding method, is not necessary, but holding pressure can be applied in a range where there is no particular problem in the next cavity volume expansion step.
  T_min= H '_max ²× (M / 1000)… Formula 1
    T_min : Minimum primary cooling time [sec]
    h '_max : Maximum thickness of the volume expansion part [mm]
    M: Mold temperature [℃]
  T_max= H '_min ²× (M / 40)… Formula 4
    T_max : Maximum primary cooling time [sec]
    h '_min : Minimum wall thickness [mm]
    M: Mold temperature [℃]
  T_min≦ T_max                        ... Formula 3
[0020]
  The expansion of the cavity volume can be performed, for example, by moving a mold by a mold clamping mechanism of an injection molding machine or moving a slide core provided in the mold. Such enlargement of the cavity volume can be performed by manual operation, but it is desirable that the cavity volume can be controlled by the molding machine or the mold mechanism itself. That is, when the cavity volume is enlarged by moving the mold by the mold clamping mechanism of the injection molding machine, it is desirable to have a control function that can arbitrarily move and stop the mold during the molding operation. Also, the speed of expanding the cavity volume is the foaming materialSex treeUsually, it is in the range of 0.1 to 10 mm / sec, although it varies depending on the shape of the foam propeller fan which is the fat composition or the final molded product. Further, the speed does not necessarily have to be constant, and the speed may be gradually increased from the initial stage of enlargement.
                                                                        more than
[0021]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples.
(1) Material
The following materials {circle around (1)} to {circle around (4)} were dry blended so that the final composition had the ratio described later, and subjected to molding.
(1) Long glass fiber reinforced resin
A glass roving with an average fiber diameter of 17μm and a tex count of 2310g / km is introduced into an impregnation tank heated to 280 ° C. : 160 ° C., melt flow rate (230 ° C., 21.18 N): 200 g / 10 min] was supplied. After impregnating the glass roving with polypropylene resin, the glass roving was pulled through a 2.3 mm diameter circular nozzle, cut to a length of 6 mm after cooling, and glass long fiber reinforced resin pellets having a glass fiber content of 50% by weight were obtained.
(2) Foaming agent master batch
A mixture of 20% by weight of blowing agent (ADCA) and 80% by weight of crystalline ethylene-propylene random copolymer (ethylene content 4.5% by weight) with a melt flow rate of 75g / 10min was melted in an extruder at 180 ° C. It knead | mixed and the foaming agent masterbatch pellet was obtained.
(3) Polypropylene for dilution
Propylene homopolymer pellets having a melt flow rate of 75 g / 10 min were used.
(4) Mica master batch
A mixture of 60% by weight of mica having an average particle diameter of 20 μm and 40% by weight of a propylene homopolymer having a melt flow rate of 60 g / 10 min was melt-kneaded in an extruder at 240 ° C. to obtain mica master batch pellets. .
[0022]
(2) Propeller fan evaluation method
(1) Wing shape
When the entire wing part is foamed, the boundary between the foamed part and the non-foamed part is the one that is sufficiently foamed to the end and when the part other than the root and outer periphery of the wing part is foamed. For those that were connected smoothly, it was judged as ○ (Fig. 3). Other cases where the foamed part and non-foamed part have a stepped shape (Fig. 4) or a wedge-shaped recess at the boundary between the foamed part and non-foamed part (Fig. 5) are judged as x. did.
(2) Product weight
The weight of five propeller fan molded products was measured and taken as the average weight.
(3) Rigidity
The propeller fan was placed horizontally, a load of 3 kg was applied to the blade tip (Fig. 1), and the amount of deflection at that time was measured. The measurement was performed on all wings, and the average value was taken.
(4) Noise
A propeller fan was attached to the DC motor, and the noise at 600 rpm was measured from a position 1 m away with a noise meter. The noise of the motor alone with the propeller fan removed was 31 dB.
[0023]
Example 1
Dry blending of material (1) 40%, material (2) 5%, and material (3) 55% by weight so that the final composition is 20% glass fiber and 1% foaming agent. Then, it was subjected to an injection molding machine set at a cylinder temperature of 200 ° C. The mold has 4 blades, 380mm outer diameter, 110mm hub diameter, 1.5mm thickness of the minimum thickness part of the wing part, 5mm thickness of the maximum thickness part, and the outer periphery of the wing part has an arcuate end. I used what is. The mold temperature was 40 ° C. The molten resin plasticized in the cylinder was injected into the mold cavity with an injection time, that is, the time of step b being 2.7 seconds. The time for forming the surface solidified layer, that is, the time of step c (hereinafter referred to as primary cooling time) was 1.5 seconds, and the opening amount of the mold was 4 mm. Further, the inside was sufficiently solidified to obtain a thick-walled foamed propeller fan molded product having a foamed structure. As a result of evaluating the obtained molded product, it was excellent in light weight and rigidity, good in the end shape, and good in low noise.
[0024]
Comparative Example 1
A foamed propeller fan molded article was obtained using the same mold and the same conditions as in Example 1 except that the outer periphery of the wing was rectangular instead of the arcuate end. Since the outer periphery of the wing portion of the mold was not an arc-shaped end, the shape of the wing end after foaming became a stepped shape, resulting in increased noise.
[0025]
Comparative Example 2
A foamed propeller fan molded product was obtained in the same manner as in Example 1 except that the primary cooling time was 4 seconds. The wing end shape after foaming became stepped and the noise increased.
[0026]
Comparative Example 3
The same mold as in Example 1 was used, but foam molding was not performed, and a non-foamed thin-walled propeller fan molded product was obtained by a normal injection molding method. Rigidity was inferior compared to foamed molded products, and noise increased due to wing shake.
[0027]
Comparative Example 4
Thick propeller fan mold with 4 blades, outer diameter 380mm, hub diameter 110mm, minimum blade thickness 2mm, maximum wall thickness 9mm, non-foamed thick by normal injection molding method Propeller fan molding was obtained. The obtained molded product was extremely heavy.
[0028]
Examples 2 and 3, Comparative Example 5
The same material as in Example 1 was subjected to an injection molding machine set at a cylinder temperature of 200 ° C. The mold has 4 blades, outer diameter 300mm, hub diameter 120mm, minimum blade thickness 2mm, maximum wall thickness 8mm, outer periphery of the blade has an arcuate end We used what is. The mold temperature was 30 ° C. Each foam molding was performed under the conditions shown in Table 1 to obtain a thick-walled foam propeller fan molded product having a foam structure. The molded products of Examples 2 and 3 were excellent in lightness and rigidity, and the terminal shape was good and the low noise property was good, but the molded product of Comparative Example 5 was a stepped wing end shape after foaming As a result, noise increased.
[0029]
Comparative Example 6
The same material as in Example 1 was subjected to an injection molding machine set at a cylinder temperature of 200 ° C. Gold with 4 blades, 300mm outer diameter, 120mm hub diameter, 0.5mm minimum wall thickness, 2mm maximum wall thickness, and the outer periphery of the blade has an arcuate end Using a mold, foam molding was performed under the conditions shown in Table 1 to obtain a thick-walled foam propeller fan molded product. Although it was appropriate as the primary cooling time, the thickness of the wing minimum wall thickness before foaming was too thin, the wing end shape after foaming was stepped, noise increased, and rigidity Was also lacking.
[0030]
Comparative Example 7
The same material as in Example 1 was subjected to an injection molding machine set at a cylinder temperature of 200 ° C. Mold with 4 blades, outer diameter of 300mm, hub diameter of 120mm, minimum thickness of blade part is 1mm, maximum thickness of 10mm, outer periphery of blade part is arcuate end Foam molding was carried out using_min≦ T_maxSince the above requirement was not satisfied, the surface solidified layer in the thick part burst and a good molded product could not be obtained.
[0031]
Comparative Example 8
The same material as in Example 1 was subjected to an injection molding machine set at a cylinder temperature of 200 ° C. The mold has 4 blades, outer diameter 300mm, hub diameter 120mm, minimum blade thickness 2mm, maximum wall thickness 8mm, outer periphery of the blade has an arcuate end We used what is. A thick-walled foamed propeller fan molded product having a foamed structure was obtained in the same manner as in Example 2 except that the injection speed was reduced and the injection time was 5.5 seconds. The obtained molded product had a stepped wing end shape after foaming, resulting in increased noise.
[0032]
Example 4
Material 1) is 20% by weight, Material 2 is 5% by weight, and Material 3 is 42% by weight so that the final composition is 10% by weight of glass fiber, 20% by weight of mica, and 1% by weight of foaming agent. A foamed propeller fan molded product was obtained in the same manner as in Example 2 except that a material obtained by dry blending material (4) at a ratio of 33% by weight was used and the primary cooling time was 3 seconds. As a result of evaluating the obtained molded product, it was excellent in light weight and rigidity, good in the end shape, and good in low noise.
[0033]
Examples 5 and 6
The same material as in Example 1 was subjected to an injection molding machine set at a cylinder temperature of 200 ° C. The mold used was one having four blades, an outer diameter of 300 mm, a hub diameter of 120 mm, and a structure in which only the central portion of the wing portion, that is, the portion excluding the root and the periphery was foamed. The foamed portion used had a minimum thickness of 2 mm before foaming, a maximum thickness of 4 mm, and the outer periphery of the wing portion having an arcuate end. Foam molding was carried out under the conditions shown in Table 1 to obtain a thick-walled foamed propeller fan molded product with a foamed structure, all of which were excellent in light weight and rigidity, good in the end shape, and good in low noise. The
[0034]
[Table 1]

[0035]
【The invention's effect】
The method for producing a foamed propeller fan of the present invention uses a mold having a specific shape, and is superior in rigidity and light weight of the wing part and has a good wing shape by a specific injection molding method and specific injection molding conditions. A foamed propeller fan excellent in low noise can be obtained. For this reason, it can endure high rotation and can obtain a high air volume. Moreover, since it is excellent in light weight, not only the material cost can be reduced, but also the power consumption of the motor can be kept low.
[Brief description of the drawings]
FIG. 1 shows an example of a foamed propeller fan obtained by the production method of the present invention (plan view).
FIG. 2 shows an example of a foamed propeller fan obtained by the production method of the present invention (side view).
FIG. 3 shows an example of a good wing shape of the present invention (cross-sectional view).
FIG. 4 shows an example of a blade shape outside the scope of the present invention (cross-sectional view).
FIG. 5 shows an example of a blade shape outside the scope of the present invention (cross-sectional view).
FIG. 6 shows an example of a blade shape before volume expansion according to the present invention (cross-sectional view).
[Explanation of symbols]
1 ... Hub
2 ... Wings
3… Outer wing circumference
4 ... wing root
5 ... tip of wing
6… Foamed part
7… Non-foamed part
8 ... Step
9 ... Wedge-shaped recess

Claims (9)

Based on the composition, the step of plasticizing the foamable resins composition containing a thermoplastic resin 95 to 99.9 wt% and a chemical blowing agent 0.1 to 5 wt% (a), than the volume of the molded article of interest Injecting the plasticized material into a small closed mold cavity (b), cooling to a state where the solidified layer contacting the mold surface and the internal molten layer are mixed after completion of injection filling (c), Foaming at least on the wings obtained by opening the mold (d) to expand the volume of the cavity to the volume of the target molded product, and (e) taking out the molded product after cooling. A foamed propeller fan having a structure in which the minimum thickness of the blade is 1 mm or more, the maximum thickness is 15 mm or less, and the outer periphery is substantially an arc-shaped end. Using the mold having the shape of the process, the time of the process b is 5 seconds or less, and c The method of manufacturing a sparkling propeller fan, characterized in that the extent of time in the range of T _min through T _max which is defined by the following equation.
T _min = h _max ² × (M / 1000)… Formula 1
T _min : Minimum primary cooling time [sec]
h _max : Maximum thickness of wings before mold opening [mm]
M: Mold temperature [℃]
T _max = h _min ² × (M / 30)… Formula 2
T _max : Maximum primary cooling time [sec]
h _min : Minimum thickness of wings before mold opening [mm]
M: Mold temperature [℃]
T _min ≦ T _max … Formula 3 Step (a) of plasticizing a foamable resin composition containing 95 to 99.9% by weight of a thermoplastic resin and 0.1 to 5% by weight of a chemical foaming agent on the basis of the composition, a portion excluding the root and outer periphery of the wing A step (b) of injecting the plasticized material into a closed mold cavity smaller than the volume of the target molded product, and a mixture of a solidified layer contacting the mold surface after completion of injection filling and an internal molten layer Step (c) of cooling to a state where it can be cooled, step (d) of expanding the volume of the cavity to the volume of the target molded product by opening the mold of the portion excluding the root and outer periphery of the wing , and further cooling A foamed propeller fan having a foamed structure at least on the wing part, which is obtained through the step (e) of taking out the molded product after performing the process, wherein the thickness of the minimum thickness part is 1 mm or more with respect to the wing part as the mold The maximum wall thickness is 15mm or less and the outer periphery is substantially arcuate Foam characterized by using an end-shaped mold, the time of the b step being 5 seconds or less, and the time of the c step being in the range of T _{min to} T _max defined by the following formula Propeller fan manufacturing method.
T _min = h ' _max ² x (M / 1000) ... Formula 1
T _min : Minimum primary cooling time [sec]
h ' _max : Maximum thickness of the volume expansion part [mm]
M: Mold temperature [℃]
T _max = h ' _min ² x (M / 40) ... Formula 4
T _max : Maximum primary cooling time [sec]
h ' _min : Minimum wall thickness [mm]
M: Mold temperature [℃]
T _min ≦ T _max … Formula 3   The foamable resin composition is a foamable resin composition containing 35 to 94.9% by weight of a thermoplastic resin, 0.1 to 5% by weight of a chemical foaming agent and 5 to 60% by weight of an inorganic filler, based on the composition. The manufacturing method of the foaming propeller fan of Claim 1 or Claim 2.   The method for producing a foamed propeller fan according to claim 3, wherein the inorganic filler is a long glass fiber having a length of 2 to 50 mm.   The method for producing a foamed propeller fan according to claim 3, wherein the inorganic filler is a mixture of glass fiber and a plate-like inorganic filler. Based on the composition, the step of plasticizing the foamable resins composition of a thermoplastic resin 40 to 95 wt% and a long glass fiber length 2~50mm containing 5 to 60 wt% (a), the objective A step (b) of injecting the plasticized material into a closed mold cavity smaller than the volume of the molded product, and cooling to a state where a solidified layer contacting the mold surface and an internal molten layer are mixed after completion of injection filling; Obtained through step (c), the step of expanding the volume of the cavity to the volume of the target molded product by opening the mold (d), and the step of removing the molded product after cooling (e) , A foamed propeller fan having a foam structure at least in the wing portion, wherein the die has a minimum thickness of 1 mm or more, a maximum thickness of 15 mm or less, and a substantially outer periphery with respect to the wing. Using a mold with an arcuate end, and the time of step b is 5 seconds or less, One method for producing a foamed propeller fan, characterized in that the time of c steps in the range of T _min through T _max which is defined by the following equation.
T _min = h _max ² × (M / 1000)… Formula 1
T _min : Minimum primary cooling time [sec]
h _max : Maximum thickness of wings before mold opening [mm]
M: Mold temperature [℃]
T _max = h _min ² × (M / 30)… Formula 2
T _max : Maximum primary cooling time [sec]
h _min : Minimum thickness of wings before mold opening [mm]
M: Mold temperature [℃]
T _min ≦ T _max … Formula 3 A step (a) of plasticizing a foamable resin composition containing 40 to 95% by weight of a thermoplastic resin and 5 to 60% by weight of a glass fiber having a length of 2 to 50 mm, based on the composition; And a step (b) of injecting the plasticized product into a closed mold cavity smaller than the volume of the target molded article except for the outer periphery, and a solidified layer that comes into contact with the mold surface after completion of injection filling Step (c) of cooling to a state where the internal molten layer is mixed , and step of expanding the cavity volume to the volume of the target molded product by opening the mold of the portion excluding the root and outer periphery of the wing. (d) a foamed propeller fan having a foam structure in at least the wing part, obtained through the step (e) of taking out the molded product after further cooling, wherein the minimum thickness part is related to the wing part as the mold The wall thickness is 1mm or more, the maximum wall thickness is 15mm or less, and the outer circumference is substantially Using a mold having a shape which is arcuate ends, the time of step b 5 seconds or less, and characterized by the time of c steps in the range of T _min through T _max which is defined by the following formula A method for producing a foamed propeller fan.
T _min = h ' _max ² x (M / 1000) ... Formula 1
T _min : Minimum primary cooling time [sec]
h ' _max : Maximum thickness of the volume expansion part [mm]
M: Mold temperature [℃]
T _max = h ' _min ² x (M / 40) ... Formula 4
T _max : Maximum primary cooling time [sec]
h ' _min : Minimum wall thickness [mm]
M: Mold temperature [℃]
T _min ≦ T _max … Formula 3   The foamable resin composition contains 40 to 95% by weight of a thermoplastic resin and 5 to 60% by weight of a mixture of long glass fibers having a length of 2 to 50 mm and a plate-like inorganic filler, based on the composition. The method for producing a foamed propeller fan according to claim 6 or 7, which is a product.   The method for producing a foamed propeller fan according to any one of claims 1 to 8, wherein the thermoplastic resin is a polyolefin resin.

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