JP2000127194A - Manufacture and device of thermoplastic resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoplastic resin molded product manufacturing method for manufacturing a molded product efficiently even when a resin is hard-to-mold. SOLUTION: A plurality of pressure-resistant chambers 3a and 3b are connected in parallel with a resin feed opening of an injection molding machine 6, and a gas impregnated resin is fed from one pressure-resistant chamber 3a into the injection molding machine 6, and simultaneously carbon dioxide gas is impregnated in the other pressure-resistant chamber 3b to manufacture a gas impregnated resin, and one pressure-resistant chamber 3a is changed over to the other pressure-resistant chamber 36 to feed the gas impregnated resin into the injection molding machine 6 continuously. The molding pressure can be reduced to a large extent particularly for a general-purpose thermoplastic resin and also a mold can be made smaller and the pressure distribution in a product generated at the time of molding can be reduced to improve the dimension accuracy by the arrangement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic resin, in particular, a resin having a high melt viscosity, which is difficult to melt-mold, a resin which is easily decomposed by heat, an additive having a low boiling point or an additive which is easily decomposed by heat. The present invention relates to a method for producing a molded article using a resin material such as a resin, and an apparatus for producing a thermoplastic resin molded article used in the production method.

[0002]

2. Description of the Related Art Among thermoplastic resins, there are moldings such as a resin having a high melt viscosity, which is difficult to melt-mold, a resin which is easily decomposed, and a resin having a low boiling point additive or an additive which is easily thermally decomposed. There are difficult resin materials (hereinafter, referred to as “hard-to-mold resins”).

For example, resins having high viscosity and difficult to melt-mold include ultrahigh molecular weight polyethylene, ultrahigh polymerization degree polyvinyl chloride, high chlorination degree polyvinyl chloride, polytetrafluoroethylene, polyimide and the like.

[0004] Resins which are easily decomposed by heat include polylactic acid,
Biodegradable resins such as polyhydroxybutyrate, polyvinyl chloride with high chlorination degree, polyacrylonitrile and the like can be mentioned.

For example, conventionally, the following method has been employed to mold a molded article from a resin having a high melt viscosity and being difficult to be melt-molded among difficult-to-mold resins.

(1) A method in which a plate-shaped or rod-shaped molded product is prepared by compression (compression) molding or ram extrusion molding, and the molded product is formed into a desired product by cutting out such as cutting.

(2) A method in which a difficult-to-mold resin is dissolved in an organic solvent and formed into a film or a sheet by a casting method.

(3) A method in which a dispersion or mixture obtained by adding an organic solvent to a difficult-to-mold resin is heated and melted, followed by shaping, followed by volatilization of the organic solvent after shaping (Japanese Patent Publication No. 4-47608).
Reference).

However, the method (1) has a disadvantage that productivity is extremely low. Also, (2),
In the method (3), in order to prevent the physical properties of the obtained molded article from being deteriorated, it is necessary to heat and evaporate the solvent after molding. However, a large-scale apparatus is required to completely evaporate the solvent. In addition, the molding time is long, the productivity is low, and the evaporation of the solvent as it is may cause environmental pollution. Therefore, there is a problem that the solvent must be recovered, and the equipment cost of the recovery equipment and the like increases.

Therefore, instead of an organic solvent, a gas in a gaseous state at normal temperature and normal pressure (hereinafter referred to as "gas") such as carbon dioxide gas (hereinafter referred to as "carbon dioxide gas") which does not cause environmental pollution. ) Is impregnated with a thermoplastic resin at normal pressure or high pressure, and a foam having a fine independent cell structure is injection-molded (JP-A-8-851).
No. 28).

That is, in the above method, one pressure-resistant chamber, which is an airtight container, is provided between the hopper of the injection molding apparatus and the screw built-in cylinder, and first, a pellet-shaped raw thermoplastic resin (hereinafter referred to as “raw resin”). Is supplied from a hopper to a pressure-resistant chamber maintained at room temperature, and the raw resin is impregnated with gas at normal pressure or high pressure in the pressure-resistant chamber to obtain a gas-impregnated resin in an easily plasticized state. Next, the gas-impregnated resin is supplied to an injection molding machine as a plasticizing device, kneaded and plasticized in the injection molding machine, and the obtained plasticized resin is injected into a mold to obtain a foam molded product. It has become.

[0012]

The amount of gas impregnated in the thermoplastic resin depends on the pressure and time as shown in FIGS. 9 and 10. Therefore, in order to impregnate the resin with a certain amount of gas, it is necessary to 1) keep the inside of the pressure-resistant chamber at a constant pressure, and 2) leave the resin in the pressure-resistant chamber for a time required for the saturated impregnation amount or more. . The above 1)
In order to satisfy the requirement, it is necessary to make the space of the pressure-resistant chamber closed in a closed state from the molding machine.

Therefore, in the above method, there is a problem that the next gas impregnation step cannot be performed unless a predetermined amount of the gas impregnation resin is supplied from the pressure-resistant chamber to the injection molding machine.

That is, when the gas impregnation and the supply of the resin to the molding machine are performed simultaneously to continuously perform the molding (when the pressure-resistant chamber and the molding machine are always connected), the molding machine receives the gas from the molding machine. Pressure is not stable due to gas leakage. In addition, the resin initially supplied to the molding machine has a small gas impregnation time because a sufficient gas impregnation time is not ensured. If the amount is too small, there is a possibility that a problem such as impossible molding may be caused. In particular, in the case of molding a foam, there is a risk of causing a problem such as a difference in the expansion ratio for each product.

Therefore, in the above method, as a result, the resin dissolving process and the molding process have to be performed in a batch system in which the process is temporally decomposed.

As a raw material resin, pellets of ultrahigh molecular weight polyethylene (size φ4 mm × 2.3 mm) having a viscosity average molecular weight of 1,000,000 or more were impregnated with carbon dioxide gas at normal temperature (20 ° C.) and a gas pressure of 10.0 MPa. However, the time required to reach the saturated impregnation amount (hereinafter referred to as “saturated impregnation time”) was 1960 minutes. Therefore, during the 1960 minutes, the supply of the resin to the injection molding machine had to be temporarily stopped.

In view of such circumstances, the present invention provides a method for producing a thermoplastic resin molded article which can efficiently produce a molded article even if the resin is difficult to mold, and a thermoplastic resin used for the production method. It is an object of the present invention to provide an apparatus for manufacturing a molded article.

[0018]

In order to achieve the above object, a method for producing a thermoplastic resin molded product according to claim 1 of the present invention (hereinafter referred to as "the production method of claim 1") is carried out at room temperature. A gas in a gaseous state at normal pressure is filled in an airtight container, and the raw material thermoplastic resin is impregnated in the airtight container to obtain a gas impregnated resin having a predetermined gas impregnation amount. A resin supply step of supplying the gas-impregnated resin to the plasticizing device connected to the airtight container via the supply path, and after the supplied gas-impregnated resin is plasticized in the plasticizing device, the obtained plasticized resin is A plurality of hermetically sealed containers connected to a plasticizing device in parallel with a supply path, wherein the one hermetic container is provided with a molding step of supplying the mold to a mold to obtain a mold-shaped molded product. Supply of gas-impregnated resin to plasticizer from When the gas impregnation process is performed in another airtight container and the supply of the gas impregnated resin from one airtight container reaches a specified amount, the supply of the gas impregnated resin is switched to the supply of the gas impregnated resin from another airtight container after the gas impregnation process is completed. At the same time, the gas-impregnating step was performed by sequentially filling the raw material thermoplastic resin into the airtight container after the supply.

According to a second aspect of the present invention, there is provided a method for producing a thermoplastic resin molded article (hereinafter referred to as “a second aspect of the present invention”). A gas impregnation step of impregnating the raw material thermoplastic resin in the airtight container to obtain a gas impregnated resin having a predetermined gas impregnation amount, and connecting the gas impregnated resin obtained in the gas impregnation step to the airtight container via a supply path. A resin supply step of supplying the plasticized resin to the plasticizing device, and after the supplied gas-impregnated resin is plasticized in the plasticizing device, the obtained plasticized resin is supplied to a mold to obtain a molded product in a mold shape. In the method for manufacturing a thermoplastic resin molded article comprising a molding step, a plurality of hermetic containers are connected in series, the lowest airtight container is connected to the plasticizing device via a supply path, and Gas impregnated resin is supplied to the plasticizer In the meantime, the gas impregnating step is performed by another good airtight container, and when the gas impregnated resin in the lowest airtight container is supplied in a specified amount, the supply path is shut off and the good airtight container is closed. After sequentially transferring the gas-impregnated resin impregnated with gas in advance to the lower hermetic container, supply of the gas-impregnated resin in the lowest hermetic container to the plasticizer was started again.

According to a third aspect of the present invention, there is provided a method for producing a thermoplastic resin molded article (hereinafter referred to as “a third aspect of the production method”). A gas impregnation step of impregnating the raw material thermoplastic resin in the airtight container to obtain a gas impregnated resin having a predetermined gas impregnation amount, and connecting the gas impregnated resin obtained in the gas impregnation step to the airtight container via a supply path. A resin supply step of supplying the plasticized resin to the plasticizing device, and after the supplied gas-impregnated resin is plasticized in the plasticizing device, the obtained plasticized resin is supplied to a mold to obtain a molded product in a mold shape. In the method for producing a thermoplastic resin molded article having a molding step, the raw material thermoplastic resin in the airtight container is heated to a temperature exceeding room temperature and lower than the melting temperature of the raw material thermoplastic resin during the gas impregnation step.

According to a fourth aspect of the present invention, there is provided a method for producing a thermoplastic resin molded article (hereinafter referred to as a “method of the fourth aspect”) comprising the structure of any one of the first to third aspects. In addition, during the gas impregnation step, the gas is kept in a high pressure state in the airtight container.

The method for producing a thermoplastic resin molded product according to claim 5 of the present invention (hereinafter referred to as “the production method of claim 5”) has the structure of any one of claims 1 to 4. In addition, the plasticizing device is an injection molding machine, and the supply path is closed when the measurement of the injection molding machine is completed.

The method for producing a thermoplastic resin molded product according to claim 6 of the present invention (hereinafter referred to as “the production method of claim 6”) is any one of claims 1, 4, and 5. In addition to the configuration of the manufacturing method, the plasticizing device is an injection molding machine, and L ≧ L _m / (N−1) × t ₁ / t ₂ [where,
L is the amount of gas-impregnated resin supplied from an airtight container at one time, L _m
Is the capacity of the molded product, N is the number of hermetic containers, t ₁ is the time required for saturated impregnation of gas in the hermetic container, and t ₂ is the time required for one molding. ] N airtight containers having the same capacity and satisfying the following equation are used.

The method for manufacturing a thermoplastic resin molded product according to claim 7 of the present invention (hereinafter referred to as “the manufacturing method of claim 7”) is not limited to the structure of the manufacturing method of claim 1 or claim 4. The molding apparatus is an extrusion molding machine, and L ≧ M / (N−
1) × t _1/3600 [where, L is a single supply of the gas impregnation resins from the airtight container, N is the number of the airtight container, t ₁ is the time required for saturation impregnation of the gas in the airtight container, M is It is the amount of extrusion per unit time of the extruder. ] N airtight containers having the same capacity and satisfying the following equation are used.

The method for producing a thermoplastic resin molded article according to claim 8 of the present invention (hereinafter referred to as “the production method of claim 8”) is described in claims 1, 2, 4, and 5. In addition to the constitution of the production method according to any one of claims 6 and 7, the raw thermoplastic resin in the airtight container is heated to a temperature exceeding room temperature and lower than the melting temperature of the raw thermoplastic resin in the gas impregnation step. I did it.

The method of manufacturing a thermoplastic resin molded product according to the ninth aspect of the present invention (hereinafter referred to as “the manufacturing method of the ninth aspect”) is the same as that of the third or eighth aspect. A jacket was provided in the airtight container, and a heating medium was supplied into the jacket to heat the raw material thermoplastic resin in the airtight container.

The method of manufacturing a thermoplastic resin article according to claim 10 of the present invention (hereinafter referred to as “the manufacturing method of claim 10”) is not limited to the structure of the manufacturing method of claim 3 or claim 8, A heater is provided in the airtight container, and the raw material thermoplastic resin in the airtight container is heated by the heater.

The method for producing a thermoplastic resin molded product according to claim 11 of the present invention (hereinafter referred to as “the production method of claim 11”) is not claimed in claim 1 and claim 6 and claim 8 to claim 8. 10. In addition to the configuration of any one of the manufacturing methods of 10, the plasticizing device is an injection molding machine, and the supply path of the gas-impregnated resin from the airtight container to the injection molding machine is closed from the time when the measurement is completed to the time when the injection is completed. The supply path of the gas-impregnated resin from the airtight container to the injection molding machine was kept open from the time when the injection was completed to the time when the measurement was completed.

On the other hand, the apparatus for producing a thermoplastic resin molded product according to claim 12 of the present invention (hereinafter referred to as “production apparatus of claim 12”) is a method for producing a thermoplastic resin raw material and a gas in a gaseous state at normal temperature and pressure. And an airtight container that can temporarily store the gas and impregnate the raw material thermoplastic resin with the gas, a plasticizer connected to the airtight container via a supply path, and plasticizing the resin supplied from the airtight container, And a mold for shaping the plasticized resin plasticized by the plasticizing device supplied from the plasticizing device into a desired shape. The airtight container is connected to the supply path in parallel, and is provided with a valve that can individually shut off the communication with the supply path.

An apparatus for manufacturing a thermoplastic resin article according to claim 13 of the present invention (hereinafter referred to as a "production apparatus of claim 13") has the same structure as that of the production apparatus of claim 12, but also has a gas impregnated state. When a specified amount of the gas-impregnated resin is sent from one airtight container to the plasticizing device, the valve is closed to shut off the space between the airtight container and the supply path, and the gas-impregnated resin impregnated with the predetermined amount of gas is filled. Open the valve of the other airtight container or the airtight container containing the gas impregnated resin with the longest gas impregnation time, and fill the airtight container that has been supplied with new raw material thermoplastic resin sequentially to perform gas impregnation. The configuration is such that a control means for controlling is provided.

According to a fourteenth aspect of the present invention, an apparatus for manufacturing a thermoplastic resin molded product (hereinafter referred to as a “fourth aspect of the invention”) is a plasticizing product. The apparatus was an injection molding machine, and all hermetic containers were formed to have the same capacity L ′ satisfying the following equation (1).

L ′ ≧ L _m / (N−1) × t ₁ / t ₂ (1) [where L _m is the capacity of the molded product, N is the number of hermetic containers, t ₁
Is the time required for the saturated impregnation of the gas in the hermetic container, and t ₂ is 1
This is the time required for each molding. The manufacturing apparatus for a thermoplastic resin molded product according to claim 15 of the present invention (hereinafter referred to as “the manufacturing apparatus of claim 15”) has a plasticizing apparatus in addition to the structure of claim 12 or claim 13. This is an extruder and has a configuration in which all hermetic containers are formed to have the same capacity L ′ satisfying the following equation (2).

[0033] L'≧ M / (N-1 ) × t 1/3600 ··· (2) [where, N is the number of the airtight container, t ₁ is the time required for saturation impregnation of the gas in the airtight container, M Is the extrusion rate per unit time of the extruder. An apparatus for producing a thermoplastic resin molded product according to claim 16 of the present invention (hereinafter referred to as “production apparatus of claim 16”) temporarily stores a raw material thermoplastic resin and a gas in a gas state at normal temperature and normal pressure. A possible airtight container, a plasticizing device connected to the airtight container via a resin supply path and plasticizing the resin supplied from the airtight container, and a plasticizing device supplied from the plasticizing device are plasticized. In a manufacturing apparatus of a thermoplastic resin molded article comprising a mold for shaping the plasticized resin into a desired shape,
The airtight container is provided with a heating means for the raw material thermoplastic resin filled therein.

An apparatus for producing a thermoplastic resin article according to claim 17 of the present invention (hereinafter referred to as “production apparatus according to claim 17”) has the structure of the production apparatus according to any one of claims 12 to 16. In addition to the above, the airtight container is provided with a heating means for the raw material thermoplastic resin filled therein.

An apparatus for manufacturing a thermoplastic resin article according to the eighteenth aspect of the present invention (hereinafter referred to as “the manufacturing apparatus of the eighteenth aspect”) is in addition to the configuration of the manufacturing apparatus of the sixteenth or seventeenth aspect. A jacket for heating the inside of the airtight container by supplying a heating medium is provided around the airtight container as heating means.

The manufacturing apparatus for a thermoplastic resin article according to the nineteenth aspect of the present invention (hereinafter referred to as “the manufacturing apparatus of the nineteenth aspect”) uses hot water as a heating medium in the manufacturing apparatus of the eighteenth aspect. I made it.

The apparatus for manufacturing a thermoplastic resin molded product according to claim 20 of the present invention (hereinafter referred to as “the manufacturing apparatus of claim 20”) is the same as the manufacturing apparatus of claim 16 or 17 except that A heater is provided as a means.

In the present invention, the term "thermoplastic resin" refers to a general term for plastics that soften when heated and exhibit plasticity and solidify when cooled, and include resins that have a high melt viscosity and are difficult to melt-mold. It also includes difficult-to-mold resins such as resins that are easily thermally decomposed, resins containing low-boiling additives or additives that are easily thermally decomposed.

Examples of the resin having a high melt viscosity which is difficult to melt-mold include ultra-high molecular weight polyethylene, high chlorinated polyvinyl chloride, ultra-high polymerization degree polyvinyl chloride, polytetrafluoroethylene, polyimide and the like.

On the other hand, examples of resins that are easily thermally decomposed include biodegradable resins such as polylactic acid and polyhydroxybutyrate, polyvinyl chloride having a high degree of chlorination, and polyacrylonitrile.

The plasticizer in the present invention is not particularly limited as long as the gas-impregnated resin can be plasticized and supplied to the mold, and examples thereof include an injection molding machine and an extrusion molding machine.

The molding method is not particularly limited as long as the resin material is fluidized with heat or a plasticizer, filled in a mold, molded, and cooled and solidified in the mold. , Extrusion molding, press molding, blow molding and the like.

In the present invention, impregnation means a state in which gas is dissolved or sorbed. In the present invention, plasticization is not particularly limited as long as it has fluidity, but usually means a molten state.

The gas used in the present invention includes:
It is not particularly limited as long as it can be easily plasticized without impairing the raw material resin by impregnation in a gaseous state at normal temperature and normal pressure, and examples thereof include, but are not limited to, inorganic gas, organic gas such as chlorofluorocarbon, and low molecular weight hydrocarbon. However, inorganic gas is preferable in that gas recovery is unnecessary.

The inorganic gas is not particularly restricted but includes, for example, carbon dioxide, nitrogen, argon, neon,
Helium, oxygen and the like can be mentioned, and these can be used alone or in combination of two or more.

Of the above-mentioned inorganic gases, carbon dioxide is most preferred because of its high solubility in the resin and a large decrease in the melt viscosity of the resin.

The predetermined gas impregnation amount is a gas amount required to achieve a target viscosity reduction rate or a gas amount required to achieve a target expansion ratio, and is a target molded product and a type of gas. , Is a value arbitrarily determined according to the type of resin, but usually, the maximum gas amount that can be impregnated into the resin at a predetermined constant pressure and temperature (hereinafter, referred to as
(Referred to as "saturation impregnation amount").

That is, as described above, the gas is impregnated into the resin and draws a curve as shown in FIG. 10 over time at a constant pressure and reaches a saturated impregnation amount. .

Therefore, in order to stabilize the gas impregnation amount S, the predetermined impregnation amount is preferably a saturated impregnation amount determined by the following equation.

The saturated impregnation amount S can be obtained from the following equations (a) and (b).

[0051]

(Equation 1) The time required for melting the gas in the thermoplastic resin can be determined in advance by any one of the following methods.

As shown in FIG. 10, the relationship between the gas impregnation amount and time is measured in advance by an experiment.

Based on the impregnation coefficient determined by the thermoplastic resin and the gas, the required impregnation amount arrival time is calculated by the following equations (c) to (e).

[0054]

(Equation 2) The permeability (also referred to as the diffusion coefficient, a constant determined by the type of gas and resin) is the minimum time dt, and the apparent surface area of the thermoplastic resin (the surface area of the pellets, etc., but not the internal surface area of the porous portion, etc.) , small thickness dt _p, multiplied by the pressure difference ΔP of small thickness, to calculate the gas permeation amount after short time. This is integrated, and the time when the target gas impregnation amount is reached is defined as a predetermined gas impregnation time.

The airtight container is not particularly limited as long as it can withstand the pressure of the gas and can uniformly impregnate the gas, but is provided with a stirring means for stirring the raw material resin such as resin pellets inside. Is preferred.

Further, the airtight container is provided with a measuring means,
When it is detected by the measuring means that a predetermined amount of the raw material resin has been supplied into the airtight container, the supply path of the raw material resin is shut off so that the raw material resin can be supplied quantitatively into the airtight container. It is preferable to be able to do so.

The measuring means is not particularly limited.
For example, a method of detecting the molding time using a timer to calculate the amount of resin used, a gravimetric method, a light reflection method, and the like can be used.

The gas may be supplied to the airtight container directly from a gas cylinder, or may be supplied under pressure using an air supply means such as a plunger pump.

An opening / closing valve is usually provided at the raw resin supply port, the gas impregnated resin discharge port and the gas supply port of the hermetic container. As the open / close valve, for example, a Y-shaped valve capable of withstanding high pressure is rotated. Means for opening and closing by a motor may be mentioned.

In the manufacturing method according to the first aspect, when three or more airtight containers are provided in parallel, after the supply of the gas impregnated resin from one airtight container is completed, the gas of the other airtight containers is removed. A long impregnation time or a gas impregnation time longer than a predetermined gas impregnation time is selected and switched to another airtight container.

In the manufacturing method of claim 1 and claim 2, the prescribed amount includes a case where a small amount remains in the hermetic container, but it is completely empty in consideration of minimizing the number of hermetic containers. It is preferable that the above condition be a specified amount.

In the production method according to claims 3 and 8, the heating temperature is limited to a temperature exceeding room temperature and lower than the melting temperature of the raw material thermoplastic resin, but is preferably as close as possible to the melting temperature.

In the manufacturing method according to the fourth aspect, the high pressure is
Although it depends on the type of resin, it shows a pressure state of 1 MPa or more, especially in a supercritical state (in the case of carbon dioxide gas,
7.2 MPa or more and 31 ° C. or more).

In the manufacturing method according to the sixth aspect, the basis for calculating the calculation formula is as follows. That is, one time spent gas impregnation resin in the airtight container t _c (seconds), one time from the gas impregnating resin ends of the airtight container until the next gas impregnating resin starting t _s (seconds), the airtight container The supply amount of the gas-impregnated resin at one time is L, the capacity of the molded product is L _m , the number of hermetic containers is N, and the time required for the saturated impregnation of the gas in the hermetic container is t ₁ (second), and the molding is performed once. the time required for t ₂ when a _{(sec), t c = L / L} m × t 2 t s = t c × (N-1) = L / L m × t 2 × (N-1)
Becomes Here, the necessary conditions for performing the continuous molding are as follows. t _s ≧ t ₁ , that is, L / L _m × t ₂ × (N−1) ≧
t ₁ . By transforming this equation, L ≧ L _m / (N−
1) × t ₁ / t ₂

It is preferable that the capacity L 'of the airtight container is L' = L.

When an injection molding machine is used as a plasticizing device
Although there is no upper limit for the capacity L ′ of the hermetic container of
The maximum resin consumption of the machine is L_iL determined by_i/
(N-1) × t₁/ T_TwoThe size is enough, the economy
L '≦ L _i/ (N-1) × t₁/
t_TwoIs more preferably satisfied.

According to a seventh aspect of the present invention, the capacity of the airtight container for continuously supplying the gas impregnated resin to an extruder capable of continuously obtaining a molded product is defined,
The basis for the calculation is as follows.

That is, the consumption time of the gas impregnated resin in one hermetic container is t _c (second), and the time from the end of the gas impregnated resin in one hermetic container to the start of the next gas impregnated resin is t _s.
(Second), the amount of gas-impregnated resin supplied from the hermetic container at one time is L, the number of hermetic containers is N, the time required for saturated impregnation of gas in the hermetic container is t ₁ (second), the unit of the extruder. Assuming that the extrusion rate per hour is M (kg / hour), t _c = L / (M / 3600) t _s = t _c × (N−1) = L / (M / 3600) × (N
-1). Here, the necessary conditions for performing the continuous molding are as follows. t _s ≧ t _1, i.e., L / (M / 3600) × (N-
1) ≧ t ₁ By transforming this equation, L ≧ M / (N
-1) a × t _1/3600.

It is preferable that the capacity L 'of the airtight container is L' = L.

When an extruder is used as the plasticizing device, the capacity L 'of the airtight container has no upper limit, but is determined by the maximum extruded amount M' of the extruder, M '/ (N-
1) a sufficient magnitude of × t _1/3600, considering the economic reasons, L'≦ M '/ (N -1) × t 1/3
It is more preferable to satisfy 600.

In the manufacturing method according to the ninth aspect, the heating medium supplied into the jacket is not particularly limited.
For example, a liquid such as water or oil, a gas such as air, and a semi-liquid such as a gel-like material can be used.

The method of supplying the heating medium is not particularly limited, and includes, for example, a method of supplying hot water from a temperature controller for adjusting the temperature of a mold for injection molding.

In the manufacturing method of the tenth aspect and the manufacturing apparatus of the twentieth aspect, the heater is not particularly limited. For example, a mantle heater, a sheathed heater, a cast heater, a hot air heater, an infrared heater, a cartridge heater, a band heater, Examples include a heater, a ceramic heater, and a high-frequency heater.

[0074]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
This will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the manufacturing method according to claim 1 and the manufacturing apparatus according to claim 12 of the present invention.

In this manufacturing method, first, a manufacturing apparatus A as shown in FIG. 1 is prepared. That is, this manufacturing apparatus A
One hopper 2, two pressure-resistant chambers 3a and 3b as airtight containers, gas cylinders 4a and 4b, a storage tank 5 as a supply path, an injection molding machine 6 as a plasticizing device, and a mold 7 Have.

The hopper 2 is made of a raw material thermoplastic resin (hereinafter, referred to as a thermoplastic resin).
(Hereinafter referred to as "raw resin"), and the lower end is divided into openable and closable outlets 21a and 21b having two valves 22a and 22b.

The outlets 21a and 21b are connected to the pressure-resistant chambers 3a and 3b having the capacity L ', respectively. That is, the pressure-resistant chambers 3a and 3b are connected to the valves 22a and 22b.
By opening and closing b, the raw resin in the hopper 2 is supplied through the discharge ports 21a and 21b.

[0079] Also, when the breakdown voltage chamber 3a (3b), the capacity L'is, the time required for one molding of the injection molding machine 6 t _2, the capacity of the molded article was L _m, L'≧ L _m / (2
-1) × t ₁ / t ₂ .

Further, the pressure-resistant chambers 3a and 3b are connected in parallel to a storage tank 5 to be described later via supply ports 32a and 32b provided with valves 31a and 31b, respectively. 41b) and a carbon dioxide gas sent under reduced pressure through a gas supply pipe 43a (43b) provided with a pressure reducing valve 42a (42b).

That is, a gas impregnated resin in a saturated impregnation state can be obtained by exposing the raw material resin supplied from the hopper 32 to a carbon dioxide gas atmosphere for a predetermined time. Then, the gas-impregnated resin obtained in one gas impregnation step is completely supplied to the storage tank 5 from the pressure-resistant chamber 3a (3b). That is, 1 of the gas impregnated resin from the pressure-resistant chamber 3a (3b)
The supply amount L per time is L '.

The time t ₁ until the raw material resin becomes a gas-impregnated resin in a saturated impregnation state in the pressure-resistant chambers 3a and 3b.
Is set so that the gas-impregnated resin in the pressure-resistant chambers 3a and 3b is completely consumed, that is, shorter than the time when all the gas-impregnated resin is supplied to the storage tank 5 as described later.

Further, the pressure-resistant chambers 3a, 3b are provided with exhaust ports 33a, 33b with valves for exhausting the gas in the pressure-resistant chambers 3a, 3b, and measuring means (not shown).

When the measuring means detects that a predetermined amount of the raw material resin has been supplied from the hopper 2 into the pressure-resistant chambers 3a, 3b, the control means automatically closes the valves 22a, 22b and the exhaust ports 33a, 33b. It has become.

The storage tank 5 includes a pressure-resistant chamber 3a.
The gas-impregnated resin supplied from (3b) can be temporarily stored, and an opening / closing valve 51 is provided between the resin and the injection molding machine 6, and the gas stored by opening the opening / closing valve 51 is stored. Injection molding machine for impregnated resin 6
Can be supplied.

The injection molding machine 6 heats and kneads the gas impregnated resin supplied through the storage tank 5 to make the resin in a plasticized state, that is, a molten state. Goods can be obtained.

Upon receiving a signal from the injection molding machine 6, the opening / closing valve 51 is closed from the completion of the metering to the completion of the injection, and is opened from the completion of the injection to the completion of the metering. .

The operation of the manufacturing apparatus A will be described below.

The exhaust port 33a (33b) is opened, and the valve 31a (31b) and the gas valve 41 are opened.
a (41b) is closed and the valve 22a (22
b) is opened, and the raw material resin is filled into the pressure-resistant chamber 3a (3b) through the discharge port 21a (21b).

A predetermined amount of the raw material resin is supplied to the pressure-resistant chamber 3 a
When the filling means (3b) is detected by the measuring means, the control means sends a signal to the valve 22a (22b), the exhaust port 33a (33b) and the gas valve 41a (41b).
To the valve 22a (22b) and the exhaust port 33a.
(33b) is closed and the gas valve 41a (4
1b) is opened, and carbon dioxide gas is supplied into the pressure-resistant chamber 3a (3b).

After a predetermined impregnation time has elapsed and a gas impregnated resin impregnated with a saturated amount of gas has been obtained, the control means sends a signal to the gas valve 41a (41b) and the valve 31a (31b), 41a
(41b) is closed, and the valve 31a (31
b) is opened, the gas impregnated resin is supplied to the storage tank 5 through the supply port 32a (32b), the valve 51 is opened, and the gas impregnated resin in the storage tank 5 is supplied to the injection molding machine 6, After the gas-impregnated resin is heated and kneaded in the injection molding machine 6 to obtain a plasticized molten resin, the molten resin is injected into the mold 7 to obtain a molded product.

When all the gas-impregnated resin in the pressure-resistant chamber 3a (3b) is supplied to the storage tank 5, the control means sends a signal to the valve 31a (31b) to send a signal to the valve 31a.
1a (31b) is closed and the steps (1) to (3) are performed again, and the valve 31 of the other pressure-resistant chamber 3b (3a) is
b (31a) is opened and the other pressure-resistant chamber 3b (3
a) The gas impregnated resin in the storage tank 5
Of the gas-impregnated resin to be started.

According to this manufacturing method, as described above, the pressure-resistant chambers 3a and 3b are provided in parallel,
(3b) is L ′ = L ≧ L _m / (N−1) × t ₁ / t ₂
While the gas impregnated resin is supplied from one of the pressure-resistant chambers 3a (3b).
Since the impregnation of the new raw material resin with carbon dioxide gas is completed in the other pressure-resistant chamber 3b (3a), a predetermined amount of carbon dioxide gas is always impregnated in the storage tank 5, and the storage tank 5 is easily plasticized. This means that the gas-impregnated resin is stored.

Therefore, there is no need to wait for gas impregnation, so that molding can be performed continuously, and productivity is improved.

Further, in order to increase the impregnation speed, it is not necessary to increase the gas pressure, so that a small pressure-resistant airtight container can be used, and the manufacturing cost of the apparatus can be reduced.

Further, in the injection molding machine 6, the opening and closing valve 51 is closed from the time when the injection resin is completely measured to the time when the injection is completed, and the opening and closing valve 51 is opened from the time when the injection is completed until the time when the measurement is completed. Therefore, the pressure-resistant chamber 3a (3
b) is sealed, and the pressure-resistant chamber 3a (3
The pressure fluctuation in b) is suppressed.

Therefore, the amount of gas impregnated in the gas impregnated resin in the pressure-resistant chamber 3a (3b) is stabilized, and a high-quality molded product can be obtained more stably.

FIG. 2 shows an embodiment of the manufacturing method according to claim 2 of the present invention.

In this manufacturing method, first, a manufacturing apparatus B as shown in FIG. 2 is prepared. That is, this manufacturing apparatus B
Two pressure-resistant chambers, a lower pressure-resistant chamber (hereinafter referred to as "lower chamber") 3c and an upper pressure-resistant chamber (hereinafter referred to as "upper chamber") 3d, are provided as airtight containers. The chamber 3d is connected in series via a valve 31d. Also, the raw material resin is supplied to the upper chamber 3d from a discharge port 21c with a valve 22c of the hopper 2b, and the lower chamber 3c and the injection molding machine 6 are connected to the valve 3c.
The structure is the same as that of the manufacturing apparatus A except that the gas impregnated resin is supplied to the injection molding machine 6 from the lower pressure chamber 3c by being connected via the lower pressure chamber 3c.

In FIG. 2, 33c and 33d are exhaust ports, 4c and
4d is a gas cylinder, 41c and 41d are gas valves, 42
c and 42d are pressure reducing valves, and 43c and 43d are gas supply pipes.

The method of manufacturing a thermoplastic resin molded article using the manufacturing apparatus B is such that the gas impregnated resin in the lower chamber 3c is supplied to the injection molding machine 6 while the hopper 2b is After supplying raw material resin from
With the valve 22c and the valve 31d closed, the gas valve 41d is opened to fill the upper chamber 3d with carbon dioxide gas of the gas cylinder 4d, and a gas impregnation step of impregnating the raw resin with carbon dioxide gas is performed.

When the gas impregnated resin in the lower chamber 3c approaches empty, the valve 22c is opened, and the gas impregnated resin impregnated with gas in the upper chamber 3d is consumed by the injection molding machine 6 at the resin consumption rate. The gas is supplied to the lower chamber 3c at a higher speed, and the gas valve 41c is opened to fill the upper chamber 3c with the carbon dioxide gas of the gas cylinder 4c, thereby ensuring the saturated state of the gas-impregnated resin in the lower chamber 3c.

When all the gas impregnated resin in the upper chamber 3d has been supplied to the lower chamber 3c, the valve 31
d, The valve 41c is closed, and the gas impregnation step is performed again in the upper chamber 3d.

According to this manufacturing method, lower chamber 3c
Before the gas-impregnated resin in the chamber becomes empty,
Since the gas-impregnated resin is obtained at d, and the gas-impregnated resin is supplied to the lower chamber 3d, there is no need to wait for gas impregnation, and molding can be performed continuously, thereby improving productivity.

Further, it is not necessary to increase the gas pressure in order to increase the impregnation speed, so that a small pressure-resistant airtight container is sufficient and the production cost of the apparatus can be reduced.

Further, since the gas can be impregnated also in the lower chamber 3c, the gas impregnated resin in a more stable gas impregnated state can be supplied to the injection molding machine 6.

FIG. 3 shows an embodiment of the manufacturing method according to claim 3 of the present invention.

In this manufacturing method, first, a manufacturing apparatus C as shown in FIG. 3 is prepared. That is, this manufacturing apparatus C
The pressure-resistant chamber 3e as an airtight container is directly connected to the injection molding machine 6
And a raw material resin supplied from a hopper (not shown) is impregnated with gas in the pressure-resistant chamber 3e, and the pressure-resistant chamber 3e includes a chamber body 35 and a chamber body 35. And a jacket 36 that covers the peripheral wall of the chamber main body 35. By passing warm water through the jacket 36 as a heating medium, the chamber body 35 can be heated.

That is, the temperature of the hot water is adjusted by the temperature controller 38 and sent to the jacket 36 from the hot water supply hose 38a.
9. It circulates in a route that returns to the temperature controller 38 through the hot water drainage hose 38b.

The gas is pressurized from the gas cylinder 34e via a pressurizing pump 42e provided in the middle of the gas supply pipe 43e, and is sent to the pressure-resistant chamber 3e.

The pressure-resistant chamber 3e is provided with a pressure gauge 37 with a contact. The pressure gauge 37 measures the gas pressure in the pressure-resistant chamber 3e. The solenoid valve 44e provided in the bypass 45e of the gas supply pipe 43e is opened and closed in accordance with the gas pressure, so that the gas pressure in the pressure-resistant chamber 3e can be adjusted to be constant.

In FIG. 3, 21e is a discharge port, 22e is a valve, 31e is a valve, 32e is a supply port, 33e is a safety valve, and 41e is a gas valve.

The method of manufacturing a thermoplastic resin molded article using the manufacturing apparatus C is as follows. First, warm water is passed through the jacket 36 to heat the chamber main body 35 to a temperature slightly lower than the melting temperature of the raw material resin exceeding normal temperature. At the same time, with the valve 31e and the gas valve 41e closed, the valve 22e is opened and the raw resin in the hopper 2e is supplied to the chamber main body 35 from the discharge port 21e.

Next, the valve 22e is closed and the gas valve 41e is opened to fill the chamber body 35 with carbon dioxide gas, and a gas impregnation step of impregnating the raw material resin with carbon dioxide gas is performed.

When the gas impregnation step is completed, the valve 31e
Is released, and the gas impregnated resin 1 in the chamber body 35 is supplied to the injection molding machine 6 to perform injection molding.

When the gas-impregnated resin in the chamber main body 35 becomes empty, the same process is repeated again.

According to this manufacturing method, the chamber body 35
Is heated, and in the gas impregnation step, the raw resin is heated to a temperature slightly lower than the melting temperature of the raw resin that exceeds normal temperature, so that the impregnation rate is faster than the conventional gas impregnation at normal temperature, and the time of waiting for gas impregnation. Can be shortened.

Impregnated material (here, high density polyethylene)
As for the rate at which the gas diffuses, the larger the diffusion coefficient, the faster the gas diffuses into the material to be impregnated, and the shorter the impregnation time. Incidentally, the relationship between the diffusion coefficient of carbon dioxide gas for high-density polyethylene and the temperature shown in FIG. 4 indicates that, in the case of high-density polyethylene, when the impregnation temperature, that is, the temperature of the pressure-resistant chamber is set to 80 ° C. with respect to room temperature, the diffusion It can be seen that the coefficient can be increased 10.3 times.

Therefore, as described above, the time required for impregnation can be reduced, and the production efficiency can be improved.

Furthermore, if the chamber body 35 is filled with gas and the interior of the chamber body 35 is kept at a high temperature and a high pressure until the raw material resin is melted, the time required for gas impregnation can be shortened. However, at the connection between the pressure-resistant chamber 35 and the injection molding machine 6, a blocking phenomenon occurs in which the molten resins are fused to each other, which may make it difficult to supply the resin to the injection molding machine 6. According to this manufacturing method, since the heating temperature is lower than the melting temperature of the resin, it can be efficiently manufactured without problems such as blocking.

The method for producing a thermoplastic resin molded product according to the present invention is not limited to the above embodiment.

For example, in the case of the manufacturing apparatus A and the manufacturing apparatus B, similarly to the manufacturing apparatus C, a heating means such as a jacket may be provided in the pressure-resistant chamber so that the raw material resin can be heated.

In the case of the manufacturing apparatus B, the capacity of the upper chamber and the capacity of the lower chamber may be different.

In the above manufacturing apparatuses A to C, the raw material resin is supplied from the hopper to the pressure-resistant chamber.
A lid is provided at the upper opening of the pressure-resistant chamber, and the lid is opened and closed by a method such as bolding.The bolt is loosened to remove the lid, and the raw resin is supplied to the pressure-resistant chamber from the opened upper opening. It does not matter.

In the above manufacturing apparatuses A to C, a pressure reducing valve is provided in the middle of the gas supply pipe so that the gas in the gas cylinder is supplied to the pressure-resistant chamber in a reduced pressure state. It is determined by the required gas impregnation amount. Therefore, the pressure reducing valve may not be provided. Further, the pressure may be increased by providing a pressure pump or the like.

In the manufacturing apparatus A, a storage tank 5 connected to each of the pressure-resistant chambers is provided at a connection portion between the plurality of pressure-resistant chambers and the molding machine, and a single resin supply port to the molding machine is provided. The supply to the molding machine may be made from two or more places.

In the manufacturing apparatus C, the chamber body is heated by passing hot water through a circulating pipe arranged in a serpentine tube. However, the jacket is formed in a tank shape, hot water is introduced from the lower end of the tank, and discharged from the upper end. It does not matter.

In the manufacturing apparatus C, the jacket only covers the side peripheral surface of the chamber main body. However, the jacket may surround the entire peripheral surface of the chamber main body.

[0129]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Using the manufacturing apparatus A shown in FIG. 1, an injection molded product was manufactured as follows.

[Manufacturing conditions] Capacity of pressure-resistant chambers 3a, 3b: 10600 cm ³ Raw material resin: polypropylene (MK411, manufactured by jpo)
B) Supply gas: Carbon dioxide gas Supply gas pressure: 1.0 MPa Impregnation time: 2 hours Molded product volume: 30 cm ³ Open / close valves 22 a and 22 b and open two pressure-resistant chambers 3
After the raw material resin was charged into the hopper 2 from the hopper 2, the open / close valves 22a and 22b were closed, and the pressure-resistant chambers 3a and 3b were closed.

Thereafter, carbon dioxide gas reduced to 1.0 MPa by the pressure reducing valves 32a and 32b was supplied from the gas cylinders 4a and 4b via the gas valves 41a and 41b.

The gas valves 41a and 41b were closed, and the inside of the pressure-resistant chambers 3a and 3b was kept at 1.0 MPa and left for 2 hours, which is the saturation impregnation time, to impregnate the resin with carbon dioxide gas.

Next, the valve 31a and the valve 51 are opened, the gas impregnated resin is supplied from the pressure-resistant chamber 3a to the injection molding machine 6 via the storage tank 5, and plasticization is performed in the injection molding machine 6, and the molded product capacity is 30 cm. Injection was carried out into the mold 7 of No. ³ to form a molded article having the shape of the mold 7 continuously in a molding cycle of 30 seconds.

Since the resin in the pressure-resistant chamber 3a became empty 160 minutes after the start of molding, the valves 41a and 31a were closed and the valve 31b was opened, and the resin impregnated in the pressure-resistant chamber 3b was similarly injection-molded. While supplying the raw material resin to the pressure-resistant chamber 3a, opening the valve 41a, and filling the pressure-resistant chamber 3a with 1.0 MPa of carbon dioxide gas through the pressure reducing valve. The inside was kept at 1.0 MPa.

That is, the gas impregnation process is performed alternately in the pressure chambers 3a and 3b, so that the gas impregnated resin is supplied to the injection molding machine 6 without interruption.

By repeating the above operation, it was possible to carry out molding without generating molding defects continuously for 24 hours.

Further, the maximum pressure at the time of injection for each molding is checked with a pressure sensor, and the result is combined with the result obtained when only the raw resin not impregnated with gas is directly supplied to the injection molding machine 6. 5 is shown.

As shown in FIG. 5, according to the manufacturing method of Example 1, the pressure of the resin not impregnated with carbon dioxide gas was increased by about 3 to 24,880 shots 24 hours after the initial molding.
It can be seen that it is possible to stably mold in a state of 0% reduction.

(Comparative Example 1) One pressure-resistant chamber (capacity:
The same manufacturing apparatus as in Example 1 was prepared except that only 10600 cm ³ ) was directly connected to the injection molding machine via a valve. First, the valve was opened and the gas impregnated resin in the pressure-resistant chamber was injected into the injection molding machine. The molded product was supplied and continuously molded in the same manner as in Example 1.

When the gas-impregnated resin in the pressure-resistant chamber became empty after about 160 minutes, the raw material resin was supplied to the pressure-resistant chamber by closing the valve. Thereafter, the valve was opened, and the supply of the gas impregnated resin in the pressure-resistant chamber to the injection molding machine was started again. That is, the molding was stopped for 25 minutes because the supply time of the raw material resin and the carbon dioxide gas was required.

Each time the pressure-resistant chamber was emptied, the above steps were repeated, and molding was continued for 24 hours. As described above, since a molding stop time of 25 minutes was required every 160 minutes, only 2530 shots and about 87.8% of the molded product of Example 1 could be molded.

Further, the maximum pressure at the time of injection for each molding was examined by a pressure sensor, and the result was combined with the result obtained when only the raw resin not impregnated with gas was directly supplied to the injection molding machine 6. 6 is shown.

As shown in FIG. 6, in the case of Comparative Example 1, since the impregnation time of the acid gas was sufficiently secured from the initial stage of molding to 320 shots, the resin not impregnated with the carbon dioxide gas as in the present invention was used. Thus, a pressure reduction effect of about 30% is obtained. However, in the molding after supplying a new raw material resin to the pressure-resistant chamber (after 321 shots), almost no pressure reduction effect is obtained at the beginning of molding. afterwards,
Since the amount of carbon dioxide gas impregnating the resin gradually increases, the pressure gradually decreases, and finally, the pressure reaches the same level as in the present invention.

When the change in weight of the molded product for each shot obtained in Example 1 and Comparative Example 1 was also examined, as shown in FIG. In the case where the method was used, the weight of the molded article was good without any variation, whereas the comparative example 1 which is the conventional manufacturing method was used.
In the case of using the above method, since the gas impregnation amount is not constant in only one pressure-resistant chamber, the pressure fluctuation for each molding shot is large, and a short shot is defective and extremely low in weight is observed.・ It is clear that weight stability cannot be obtained.

Example 2 Polypropylene (MK411B, manufactured by jpo) was supplied as a raw material resin to a chamber body 35 having a capacity of 10600 cm ³ of a manufacturing apparatus C shown in FIG. While circulating warm water, carbon dioxide gas pressurized to 10 MPa by the pressurizing pump 42e is charged into the chamber main body 35, and while maintaining this state, the valve 31e is slightly opened at regular intervals to impregnate a small amount of gas. The resin was extracted, its weight was measured, and the carbon dioxide gas impregnation rate at regular time intervals was calculated using the following equation (f).

[0147]

(Equation 3) (Comparative Example 2) The carbon dioxide impregnation rate was calculated at regular intervals in the same manner as in Example 2 except that the interior of the chamber body 35 was kept at 20 ° C without circulating warm water through the jacket 36.

When the carbon dioxide gas impregnation rate with respect to the time of the carbon dioxide gas impregnation rate for each fixed time calculated in Example 2 and Comparative Example 2 was plotted, an increase curve as shown in FIG. 8 was shown.

From FIG. 8, it can be seen that when heated to 90 ° C. as in Example 2, the gas is impregnated to a saturated state in 136 minutes, and it takes 1960 minutes at 20 ° C. as in Comparative Example 2.

That is, the time required for gas impregnation is 1 /
It is well understood that the production efficiency is improved.

[0151]

The method and apparatus for manufacturing a thermoplastic resin molded article according to the present invention are constructed as described above, so that not only general-purpose thermoplastic resin but also difficult-to-mold resin can be used efficiently. A molded article can be manufactured well. Particularly for general-purpose thermoplastic resins, the molding pressure can be greatly reduced, the size of the mold can be reduced, the pressure distribution in the product generated during molding can be reduced, and the dimensional accuracy can be improved.

In particular, according to the sixth and fourteenth aspects, the waiting time for gas impregnation is eliminated, the injection molding can be performed continuously, and a molded product of stable quality can be obtained.

Further, according to the seventh and fifteenth aspects, the waiting time for gas impregnation is eliminated, and even a difficult-to-mold resin can be extruded smoothly and with stable quality.

According to the eleventh aspect, the amount of gas impregnated in the gas impregnated resin in the hermetic container is small, and a molded product with more stable quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of a manufacturing apparatus for explaining one embodiment of a manufacturing method according to claim 1;

FIG. 2 is a schematic view of a manufacturing apparatus for explaining one embodiment of a manufacturing method according to a second embodiment.

FIG. 3 is a schematic view of a manufacturing apparatus for explaining one embodiment of a manufacturing method according to a third embodiment.

FIG. 4 is a graph showing a relationship between a temperature during resin impregnation and a gas diffusion coefficient.

FIG. 5 is a graph showing the results when the production method of Example 1 was performed for 24 hours.
6 is a graph comparing the change in the measurement result of the injection pressure for each injection molding with the case of the conventional manufacturing method.

FIG. 6 shows the results when the production method of Comparative Example 1 was performed for 24 hours.
6 is a graph comparing the change in the measurement result of the injection pressure for each injection molding with the case of the conventional manufacturing method.

FIG. 7 is a graph comparing the changes in the product weight of the molded products obtained in each injection molding in Example 1 and Comparative Example 1.

FIG. 8 is a graph comparing the gas impregnation rates of Example 2 and Comparative Example 2 over time.

FIG. 9 is a graph showing a relationship between a gas pressure and a saturated gas impregnation amount.

FIG. 10 is a graph showing a time course of a gas impregnation amount under a constant gas pressure.

[Explanation of symbols]

 3a to 3e Pressure-resistant chamber (airtight container) 5 Storage tank (supply path) 6 Injection molding machine (plasticizer) 7 Mold 8 Raw material resin 36 Jacket

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B29K 105: 04 F term (Reference) 4F074 AA17 AA35 AA39 AA40 AA49 AA65 AA68 AA74 AA97 AB01 BA32 BA33 CA22 CA26 CC23X CC64 4F206 AA11 AB16 AK09 AL02 AL03 AL20 JA04 JA07 JE06 JE16 JF01 JF11 JF12 JF23 JL02 JM01 4F212 AA11 AB02 AB16 AG20 AL02 AL03 AL20 AM20 UA09 UB01 UF06 UF23 UG07 UN11

Claims (20)

[Claims] A gas impregnating step of filling a gas in a gaseous state at normal temperature and normal pressure into an airtight container and impregnating a raw material thermoplastic resin in the airtight container to obtain a gas impregnated resin having a predetermined gas impregnation amount;
A resin supply step of supplying the gas-impregnated resin obtained in the gas-impregnation step to a plasticizer connected to the hermetic container via a supply path, and after the supplied gas-impregnated resin is plasticized in the plasticizer, In the method for producing a thermoplastic resin molded product comprising a molding step of supplying the obtained plasticized resin to a mold to obtain a molded product in a mold shape, a plurality of hermetic containers are connected in parallel to the supply path, At the same time as supplying the gas-impregnated resin from one hermetic container to the plasticizing device, the gas-impregnating process is performed in another hermetic container. When the supply of the gas-impregnated resin from one hermetic container reaches a specified amount, the gas impregnating process is performed. While switching to the supply of gas-impregnated resin from other hermetic containers where
A method for producing a molded article of thermoplastic resin, characterized in that a gas-impregnating step is carried out by sequentially filling a new raw material thermoplastic resin into an airtight container after the supply. 2. A gas impregnating step of filling a gas in a gaseous state at normal temperature and normal pressure into an airtight container and impregnating a raw material thermoplastic resin in the airtight container to obtain a gas impregnated resin having a predetermined gas impregnation amount;
A resin supply step of supplying the gas-impregnated resin obtained in the gas-impregnation step to a plasticizer connected to the hermetic container via a supply path, and after the supplied gas-impregnated resin is plasticized in the plasticizer, And a molding step of supplying the obtained plasticized resin to a mold to obtain a mold-shaped molded product.In the method for producing a thermoplastic resin molded product, a plurality of airtight containers are connected in series, and a supply path is formed. The lowermost hermetic container is connected to the plasticizer through a gas-impregnating process while the gas-impregnated resin in the lowermost hermetic container is supplied to the plasticizer. When the gas impregnated resin in the lowermost hermetic container is supplied in a specified amount, the supply path is shut off, and the gas impregnated resin previously impregnated in the upper hermetic container is sequentially transferred to the lower hermetic container. After changing, the least airtight again Method for producing a thermoplastic resin molded article, characterized in that to start supplying the gas impregnation resin in vessel plasticizing device. 3. A gas impregnation step of filling a gas in a gaseous state at normal temperature and pressure into an airtight container and impregnating the raw material thermoplastic resin in the airtight container to obtain a gas impregnated resin having a predetermined gas impregnation amount;
A resin supply step of supplying the gas-impregnated resin obtained in the gas-impregnation step to a plasticizer connected to the hermetic container via a supply path, and after the supplied gas-impregnated resin is plasticized in the plasticizer, In the method for producing a thermoplastic resin molded article comprising a molding step of supplying the obtained plasticized resin to a mold to obtain a molded article in a mold shape, the raw thermoplastic resin in an airtight container during the gas impregnation step, A method for producing a thermoplastic resin molded article, comprising heating to a temperature higher than room temperature and lower than the melting temperature of the raw material thermoplastic resin. 4. The method for producing a thermoplastic resin article according to claim 1, wherein the gas is kept in a high pressure state in the airtight container during the gas impregnation step. 5. The plasticizer according to claim 1, wherein the plasticizing device is an injection molding machine, and the supply path is closed when the injection molding machine has finished measuring.
The method for producing a thermoplastic resin molded product according to any one of the above. 6. The plasticizer is an injection molding machine, wherein L ≧ L
_m / (N−1) × t ₁ / t ₂ [where L is the amount of gas-impregnated resin supplied from the airtight container at one time, L _m is the volume of the molded product,
N is the number of the airtight container, t ₁ is the time required for saturation impregnation of the gas in the airtight container, t ₂ is the time required for forming a single. The method for producing a thermoplastic resin molded product according to any one of claims 1, 4 and 5, wherein N airtight containers having the same capacity and satisfying the following expression are used. 7. The plasticizer is an extruder, wherein L ≧ M.
/ (N-1) × t 1/3600 [where, L is a single supply of the gas impregnation resins from the airtight container, N is the number of the airtight container,
t ₁ is the time required for the saturated impregnation of the gas in the airtight container, and M is the amount of extrusion per unit time of the extruder. The method for producing a thermoplastic resin molded product according to claim 1 or 4, wherein N airtight containers having the same capacity and satisfying the following formula are used. 8. The method according to claim 1, wherein the raw material thermoplastic resin in the airtight container is heated to a temperature higher than room temperature and lower than the melting temperature of the raw material thermoplastic resin in the gas impregnation step. A method for producing a thermoplastic resin article according to any one of claims 6 and 7. 9. A thermoplastic resin molded article according to claim 3, wherein a jacket is provided in the hermetic container, and a heating medium is supplied into the jacket to heat the raw thermoplastic resin in the hermetic container. Method. 10. A thermoplastic resin molded product according to claim 3, wherein a heater is provided in the airtight container, and the raw material thermoplastic resin in the airtight container is heated by the heater. Method. 11. A plasticizing device is an injection molding machine, wherein a supply path of a gas impregnated resin from an airtight container to an injection molding machine is closed from a time when the measurement is completed to a time when the injection is completed, and the measurement is completed when the injection is completed. 1, 2, 3, 4, 5, 6, and 8, the supply path of the gas impregnated resin from the airtight container to the injection molding machine is kept open until A method for producing a thermoplastic resin article according to any one of claims 9 and 10. 12. A hermetic container capable of temporarily storing a raw material thermoplastic resin and a gas in a gaseous state at normal temperature and normal pressure and impregnating the raw material thermoplastic resin with the gas, and connected to the hermetic container via a supply path. Thermoplasticity comprising a plasticizing device for plasticizing the resin supplied from the airtight container, and a mold for shaping the plasticized resin plasticized by the plasticizing device supplied from the plasticizing device into a desired shape. In the apparatus for manufacturing a resin molded product, the airtight container has a plurality of the airtight containers, and the airtight containers are connected to the supply path in parallel, and include a valve that can individually shut off a communication state with the supply path. An apparatus for producing a thermoplastic resin molded product. 13. When the gas-impregnated resin impregnated with the gas is sent from one airtight container to the plasticizing device in a predetermined amount, the valve is closed to shut off the space between the airtight container and the supply path.
Open the valve of the other gas-tight container filled with the gas-impregnated resin impregnated with a predetermined amount of gas or the gas-impregnated resin filled with the gas-impregnated resin with the longest gas impregnation time. The apparatus for producing a thermoplastic resin molded product according to claim 12, further comprising a control unit configured to control so as to perform gas impregnation by filling the thermoplastic resin. 14. The heat according to claim 12, wherein the plasticizing device is an injection molding machine, and all the hermetic containers are formed to have the same capacity L ′ satisfying the following formula (1). Manufacturing equipment for plastic molded products. L ′ ≧ L _m / (N−1) × t ₁ / t ₂ (1) [where L _m is the capacity of the molded product, N is the number of hermetic containers, t ₁
Is the time required for the saturated impregnation of the gas in the hermetic container, and t ₂ is 1
This is the time required for each molding. ] 15. The heat according to claim 12, wherein the plasticizing device is an extruder, and all the hermetic containers are formed to have the same volume L ′ satisfying the following equation (2). Manufacturing equipment for plastic molded products. L'≧ M / (N-1 ) × t 1/3600 ··· (2) [where, N is the number of the airtight container, t ₁ is the time required for saturation impregnation of the gas in the airtight container, M is extruded It is the amount of extrusion per unit time of the machine. ] 16. An airtight container capable of temporarily storing a raw material thermoplastic resin and a gas in a gaseous state at normal temperature and normal pressure, and connected to the airtight container via a resin supply path to plasticize the resin supplied from the airtight container. Plasticizing device, and a thermoplastic resin molded product manufacturing device comprising a mold for shaping the plasticized resin plasticized by the plasticizing device supplied from the plasticizing device into a desired shape, An apparatus for producing a thermoplastic resin molded product, wherein the hermetic container is provided with a heating means for the raw material thermoplastic resin filled therein. 17. An airtight container provided with heating means for a raw material thermoplastic resin filled therein.
The apparatus for producing a thermoplastic resin molded product according to any one of the above. 18. A heating means is provided around the airtight container,
18. The thermoplastic resin molded article manufacturing apparatus according to claim 16, wherein the jacket is a jacket for heating the inside of the airtight container by supplying a heating medium. 19. The apparatus for producing a thermoplastic resin article according to claim 18, wherein the heating medium is hot water. 20. The apparatus for manufacturing a thermoplastic resin article according to claim 16, wherein the heating means is a heater.