JP2006142500A - Manufacturing method of bathtub - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a bathtub which prevents the closure of a mixer or piping, has high productivity and can reduce a manufacturing cost. <P>SOLUTION: A female mold is arranged so as to provide a predetermined interval with respect to a thermoplastic resin molded product preliminarily molded into a predetermined shape to form a cell and a curing agent-containing resin material, which is obtained by mixing a polymerization curing agent and a polymerizable resin raw material by a mixer in a state that the peripheral part of the thermoplastic resin molded product and the peripheral part of the female mold are sealed to perform mold clamping, is injected on the cell from the injection port of the female mold and cured to manufacture the bathtub. In this manufacturing method, the curing agent-containing resin material is injected in the cell from the mixer arranged at the injection port of the female mold and the inside of the mixer is subsequently substituted with the polymerizable resin raw material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a bathtub in which a thermoplastic resin molded article is reinforced with a cured product of a curing agent-containing resin raw material.

  Conventionally, various products having a strength improved by laminating a fiber reinforced resin (sometimes referred to as FRP) on the back surface of a resin molded product have been put on the market. For example, bathtubs and wash bowls that are reinforced by laminating an FRP layer on the back surface of an acrylic resin layer having an excellent appearance instead of a gel coat layer as a surface layer are on the market.

  In many cases, a resin molded product obtained by vacuum molding, pressure forming, press molding or the like has a small thickness. In this case, the shape of the resin molding alone cannot be maintained, and the strength may be insufficient during use, and it is necessary to reinforce by stacking an FRP layer or the like. Furthermore, since the upper limit of the use temperature is generally low with a resin molded product alone, reinforcement by lamination of the above-mentioned FRP layer or the like may be necessary from that point.

  On the other hand, the FRP layer is usually laminated by a hand lay-up method or a spray-up method, but this method is mostly manual work and requires work and time. In addition, there are many factors that deteriorate the working environment, such as solvent evaporation and glass fiber scattering.

  Patent Document 1 discloses a manufacturing method for a laminate in which a thermoplastic resin molded article formed by vacuum molding and a resin containing a filler are filled between a mold, polymerized and cured, and integrated as a technique that can improve the working environment. It is disclosed.

  In this method, the resin containing the filler is filled in advance between the vacuum-molded thermoplastic resin molded product and the mold, so that the evaporation of the solvent is not scattered in the outside air and the glass is not scattered. As a whole, the bathtub can be manufactured extremely easily, and the work can be performed under a good working environment.

  The reinforcing layer of the above-described thermoplastic resin molded product is prepared by mixing and curing a polymerization curing agent and a polymerizable resin raw material, and there are various mixing methods. For example, after charging a predetermined amount of each material into the container, a method of mixing with a hand mixer for stirring can be mentioned. It is difficult to mix uniformly throughout the container by this mixing method, and the uniformity of the mixture varies depending on the skill level of the operator. For example, in the bottom or corner of a container that is difficult to reach with the stirring blades of a hand mixer, mixing may be uneven if the skill level of the operator is low. When molding with such a non-uniform mixture, there may be a problem that the curing becomes non-uniform. Also, if too much time is stirred to make a mixture with sufficient uniformity, problems such as gelation in the container during the mixing operation or gelation during the injection into the cell may occur. was there. Furthermore, since it is necessary to remove the mixture adhering to the container after the injection into the cell, there is a problem that this operation takes time and effort.

  In order to solve such a problem, a method of manufacturing a bathtub that is supplied from a storage tank in which each material is stored to a stationary in-pipe mixer with a supply pump and mixed, and then injected into a cell has been proposed ( For example, see Patent Document 2.) With such a manufacturing method, a method for manufacturing a resin bathtub in which the labor of mixing materials is saved and the stabilization of quality is improved is widely used.

  However, when a polymerizable resin raw material with a large amount of filler or reinforcing fiber agent or a polymerizable resin raw material with a high viscosity is used, the difference in viscosity from the polymerization curing agent becomes large, so that mixing is not sufficiently performed and stirring spots are not obtained. Is likely to occur. In order to completely mix such materials, a large number of elements are required in the static in-tube mixer, so that the length of the straight pipe portion in which the elements of the mixer are accommodated becomes long. In consideration of pressure loss in mixing, the inner diameter of the tube is proportional to the viscosity of the material to be mixed. Furthermore, it is necessary to eliminate the gap in order to prevent the polymerization curing agent from passing through the gap between the element and the mixer housing. Therefore, a static in-pipe mixer in which the element and the mixer housing are welded all around is used. As the static type in-tube mixer, a steel one is generally used. Under these conditions, the static type in-tube mixer has a long straight pipe portion, a large diameter, and a heavy specification.

  When a mixer having such a specification is attached to the injection port of the mold, there is a problem that the injection facility becomes large and the workability of maintenance that requires the work of detaching the mixer deteriorates. Therefore, the mixer was separated from the inlet, placed in a place where maintenance was easy, and a flexible pipe was interposed between the mixer and the inlet.

  However, when piping is interposed in this way, molding is performed even if the temperature of the polymerizable resin raw material and polymerization curing agent storage tank is controlled to a desired temperature and a curing agent-containing resin material at a desired temperature is injected into the cell. Due to the transfer of heat in the pipe portion interposed depending on the environmental temperature at the site, the curing agent-containing resin material could not be supplied into the cell at the desired temperature, and the curing time could vary.

  In order to solve the above-described problems, a heat insulating material or a rubber heater is sometimes wound around the pipe. However, when the heat insulating material is wound, the flexibility of the piping is remarkably lowered and the handling property and workability are deteriorated. Wrapping a rubber heater requires care when handling the piping, so workability is poor, and excessive heat may be applied to the curing agent-containing resin material. Supplying into the cell becomes difficult.

  Furthermore, when using a curing agent-containing resin material with a short curing time, if piping with a large ratio of the length / inner diameter of the piping is used, it takes time to inject, and a predetermined amount of the curing agent-containing resin material into the cell. Before the injection is completed, the curing reaction of the curing agent-containing resin material initially injected into the cell starts, and there is a case where the curing timing is shifted for each part, and the molded product is cracked or deformed after curing. It was. For this reason, it is desirable that the piping used be as short as possible and have a large inner diameter, but such piping has not been used because of poor handling.

  Further, if the curing agent-containing resin material is supplied into the cell and then left as it is, the curing agent-containing resin material remaining in the pipe and the mixer is cured. For this reason, the piping and the mixer need to be cured to prevent curing, such as discharging the curing agent-containing resin material with compressed air or the like and performing sufficient cleaning with a solvent or the like.

  However, even if the above-described measures for preventing curing are performed, the curing agent-containing resin material gradually adheres and is laminated on the inner wall of the pipe. As a result, the pressure loss in the pipe increases, and therefore, it has been necessary to frequently perform an operation for removing the hardened material containing the hardener that has been fixed, such as removing the pipe and soaking it in a solvent. In the case where measures for preventing hardening are not sufficiently taken, the curing agent-containing resin material is hardened in the pipe and the mixer, which may necessitate replacement of the pipe and disposal of the expensive mixer. The curing agent-containing resin material discharged by the compressed air and the like, and the cleaning agent, piping, and mixer used for cleaning contribute to an increase in manufacturing cost.

JP-A-5-237854 JP 2004-249582 A

  The present invention has been made to solve such problems, and prevents clogging of mixers and pipes due to curing of the curing agent-containing resin material, which is highly productive and stable, and can reduce manufacturing costs. It aims at providing the manufacturing method of a bathtub.

The present invention, which has solved the above problems, forms a cell by disposing a female mold with a predetermined distance from a thermoplastic resin molded product that has been previously molded into a predetermined shape, and a peripheral portion of the thermoplastic resin molded product, In a state where the periphery of the female mold is sealed and the mold is clamped, the curing agent-containing resin material obtained by mixing the polymerization curing agent and the polymerizable resin raw material with a mixer is supplied from the inlet of the female mold to the cell. In the method of manufacturing a bathtub for injecting into the inside and curing the same, after injecting the curing agent-containing resin material into the cell from the mixer installed at the inlet of the female mold, the polymerization in the mixer is performed. It is the manufacturing method of the bathtub characterized by substituting with a functional resin raw material.
In addition, it is preferable to replace the inside of the mixer with a curing agent-containing resin material in advance when injecting into another cell.
Further, the mixer is a rotary mixer provided with a mixing head in which a rotating body having a plurality of protrusions and flow paths is housed in a tubular mixer housing having a nozzle attached to the tip. It is preferable.
Moreover, it is preferable that the said mixing head is a disposable mixing head.

  In the method of manufacturing a bathtub of the present invention, after injecting the curing agent-containing resin material into the cell from the mixer installed in the female injection port, by replacing the inside of the mixer with a polymerizable resin raw material, Curing of the curing agent-containing resin material in the mixer and piping, and blockage of the mixer and piping due to this can be prevented. This reduces (a) materials such as hardener-containing resin materials and cleaning agents that have been discarded to prevent clogging of mixers and piping, materials such as mixers and piping that have been discarded due to clogging, Intervention piping between the injection port and the mixer can be eliminated, and maintenance workability can be improved and manufacturing costs can be reduced. In addition, (b) the hardener-containing resin material can be injected into the cell at a desired temperature throughout the year, regardless of the environmental temperature at the molding site, and it has become possible to stably produce products of uniform quality. .

  In FIG. 1, sectional drawing of the shaping | molding die which installed the thermoplastic resin molded product (11) in one Embodiment of the manufacturing method of this invention is shown. According to the present invention, a cell (16) is formed by disposing a female mold (12) with a predetermined interval from a thermoplastic resin molded article (11) molded in advance in a predetermined shape, and the thermoplastic resin molded article In a state where the periphery of (11) and the periphery of the female mold (12) are sealed with a sealing material (14) and the mold is clamped, the polymerization curing agent and the polymerizable resin raw material are mixed in a mixer (shown in FIG. 2). In this embodiment, the curing agent-containing resin material obtained by mixing in (22) is injected into the cell (16) from the injection port (15) of the female mold (12) and cured. In the manufacturing method of the bathtub to be made, after injecting the curing agent-containing resin material into the cell (16) from the mixer (22) installed in the inlet (15) of the female mold (12), the inside of the mixer (22) A method for manufacturing a bathtub, characterized by substituting a polymerizable resin raw material. .

  Examples of the thermoplastic resin molded article (11) that can be used in the present invention include those obtained by thermoforming a resin plate by vacuum molding, pressure molding, press molding, or the like, or manufactured by injection molding a molding material. Etc.

  As the thermoplastic resin molded article (11), a resin molded article such as methacrylic resin, polystyrene resin, ABS resin, polypropylene resin, polycarbonate resin, and vinyl chloride resin that can be thermoformed or injection-molded can be used. Among them, a methacrylic resin molded product is particularly preferable because of excellent hydrolysis resistance and little decrease in adhesion. Among methacrylic resin molded products, methyl methacrylate alone or a methacrylic resin obtained by polymerizing a monomer comprising methyl methacrylate 60% by mass or more and acrylic ester 40% by mass or less in the presence of a polymerization initiator. What was shape | molded using the board is more preferable. In addition, a part of the monomer is polymerized in advance to produce syrup which is a mixture of the polymer and the monomer, and then 0.02-1.0 part by mass of the crosslinking agent with respect to 100 parts by mass of the syrup. And a methacrylic resin plate obtained by cast polymerization in a mold and having excellent thermoforming processability and solvent resistance are more preferred.

  The thickness of the thermoplastic resin molded article (11) is not particularly limited. However, if the thickness is too thin, cracks may occur due to contact with a solvent, and thus the thickness is preferably 0.3 mm or more. More preferably, it is 8 mm or more. Moreover, when the thermoplastic resin molded product (11) is transparent, it may be printed on the back side or laminated with a film.

  When the curing agent-containing resin material is supplied into the cell (16), the thermoplastic resin molded article (11) is preliminarily from 30 ° C. to a load deflection temperature of the thermoplastic resin molded article (11) minus 40 ° C. It is preferable that the temperature is maintained within a range selected. More preferably, it is maintained at a temperature in the range of 35 to 50 ° C. If the temperature of the thermoplastic resin molded body (11) is too low, the temperature of the atmosphere in the cell (16) is lowered by the thermoplastic resin molded body (11) installed in the cell (16), and the curing agent-containing resin material becomes When the thermoplastic resin molded body (11) is cooled, it takes a long time to be cured, and the productivity is lowered. When the temperature of the thermoplastic resin molded body (11) is too high, when the thermoplastic resin molded article (11) is installed in the cell (16), or when the curing agent-containing resin material is injected into the cell (16). In addition, the thermoplastic resin molded article (11) is likely to be deformed or the surface is easily damaged. The deflection temperature under load is obtained by measurement according to JIS K7191.

  As a method for maintaining the temperature of the thermoplastic resin molded article (11), in addition to a furnace heating method, an infrared heating method, etc., the thermoplastic resin molded article (11) is left on the temperature-controlled male mold (13) to maintain the temperature. A method of holding a temperature by interposing a thermoplastic resin molded article (11) between the temperature-controlled male and female molds (12) and (13), and a thermoplastic resin molding between the male and female molds (12) and (13). A method of heating the thermoplastic resin molded article (11) together with the mold in the furnace to maintain the temperature, the female mold (12) or the male mold (13) with a thermoplastic resin molded article ( 11) is installed and left in the furnace until the thermoplastic resin molded article (11) is warmed. Among these, a heating method by furnace heating, which is a method capable of uniformly heating the entire thermoplastic resin molded article (11), is preferable.

  Examples of the polymerizable resin material that can be used in the present invention include unsaturated polyester resins, (meth) acrylic resins, vinyl ester resins, urethane resins, epoxy resins, and resins obtained by modifying these. . As unsaturated polyester resins, ortho-, iso-, tele- or bis-unsaturated polyester resins, (meth) acryl-modified unsaturated polyester resins, and (meth) acrylic resins added to such unsaturated polyester resins And unsaturated polyester resins. The raw material for the polymerizable resin is not limited to these, and has an affinity for the thermoplastic resin molded article (11) used in the present invention, and is in close contact with the thermoplastic resin molded article (11) when polymerized and cured. Anything is possible.

  Moreover, the polymerizable resin raw material may contain a filler. As the filler, aluminum hydroxide, calcium carbonate, silica or the like can be used. Furthermore, reinforcing fiber agents such as glass fibers, carbon fibers, and organic fibers can be used. These fillers and reinforcing fiber agents can be used alone or in combination of two or more.

  The polymerizable resin raw material is preferably heated and held at a predetermined temperature. The heating and holding temperature is preferably within ± 10 ° C., more preferably within ± 5 ° C., relative to the temperature of the thermoplastic resin molded article (11) to be used. When the heating and holding temperature of the polymerizable resin raw material is set to a temperature within ± 10 ° C. with respect to the temperature of the thermoplastic resin molded article (11), the time required for curing is constant and the mold is always removed in a constant cured state. be able to. Thereby, the bathtub of uniform quality can be manufactured with the stable production amount.

The method of heating and holding the polymerizable resin material is not particularly limited, and examples thereof include a method of heating and keeping the polymerizable resin material stored in a storage tank or the like at a predetermined temperature.
The polymerizable resin raw material preferably has a viscosity of 100 to 8000 mPa · s at the temperature when supplied to the cell (16) part. When the viscosity is 100 mPa · s or more, when the polymerizable resin raw material contains a filler or a reinforcing fiber agent, the settling rate of the filler and the reinforcing fiber agent becomes slow, and the pump is transported to the mold. It is preferable that the filler and the reinforcing fiber agent do not settle in the cell (16) after injection into the tube or the cell (16). Further, the density distribution of the filler and the reinforcing fiber agent does not become uneven in the thickness direction of the formed reinforcing layer. For this reason, the deformation | transformation of the bathtub after hardening resulting from the hardening time difference in each site | part of the reinforcement layer formed, and the mechanical strength of the obtained bathtub do not become non-uniform | heterogenous. Further, when the viscosity is 8000 mPa · s or less, filling with the curing agent-containing resin material does not take time and can be easily injected. This can prevent unfilling of the cell (16) due to the progress of gelation during filling.

  As a method of supplying the polymerizable resin raw material to the mixer (22), a material such as a sine pump (registered trademark), a gear pump, a rotary pump, a snake pump, a plunger pump, a diaphragm pump, a tube pump and a hose pump is generally used. The method using the pump used for the transportation of can be mentioned. It is preferable to select a pump with less pulsation in consideration of reducing the burden on the mixer (22) due to the pump supply pressure and workability, such as a gear pump, sine pump (registered trademark), rotary pump, snake pump, tube pump, etc. Is preferably selected. Furthermore, when the addition rate of the filler or the reinforcing fiber agent is high and the viscosity of the polymerizable resin raw material is high, it is preferable to select a sine pump (registered trademark) or a rotary pump.

  The curing agent that can be used in the present invention is preferably a curing agent having a 10-hour half-life temperature of 100 to 120 ° C. in order to rapidly and efficiently proceed the curing in the cell (16). It is more preferable to use two or more kinds of curing agents having different initial temperatures of 3 ° C. or more in combination. In particular, it is preferable to use two or more kinds of room temperature curing type curing agents such as ketone peroxides such as methyl ethyl ketone peroxide and acetylacetone peroxide.

  The amount of the polymerization curing agent is usually preferably 0.3 to 5 parts by mass with respect to 100 parts by mass of the polymerizable resin raw material. It is preferable to use the polymerization curing agent in such a range because the curing reaction can be reliably started and cured quickly, and the cost can be reduced.

  Examples of a method for supplying the polymerization curing agent to the mixer (22) include a method using a metering pump such as a gear pump, a diaphragm pump, or a plunger pump.

  Moreover, in order to ensure the discharge quantitative property from each supply pump of polymeric resin raw material and polymerization hardening | curing agent, it is preferable to use the discharge amount feedback control which senses discharge amount and feeds back to a pump and controls discharge amount.

  The mixer (22) is installed in the inlet (15) of the female mold (12), and immediately before being injected into the cell (16), the polymerizable resin raw material and the polymerization curing agent are mixed to obtain a curing agent-containing resin material. It is important to prepare and inject into the cell (16). By installing the mixer (22) at the inlet (15), the pipe interposed between the inlet (15) and the mixer (22) can be made shorter. Alternatively, piping can be eliminated.

  The mixer (22) is preferably compact, and for example, a rotary mixer is preferably used. An exemplary configuration of a rotary mixer (22) that can be preferably used in the present invention is schematically shown in FIG. The rotary mixer (22) is a rotating body (Mixin Groter with a plurality of protrusions and flow paths provided inside a tubular mixer housing (sometimes referred to as a stator) having a nozzle attached to the tip. It is a mixer (22) provided with a mixing head (23) that houses a container (which may be represented). The rotary mixer (22) stirs and mixes the material injected into the stator by rotating the mixing grotter. The degree of mixing can be adjusted by the number of rotations of the rotor drive motor (21) that drives the Mixin Groter. Adjustment of the discharge amount of a rotary mixer (22) can be performed by adjusting the discharge amount of each supply pump of polymeric resin raw material and a polymerization hardening agent. As the stator and the mixer rotator of the rotary mixer (22), those made of steel such as stainless steel or resin can be used. Considering handling and handling at the time of curing of the curing agent-containing resin material in the mixing head (23), it is preferable that the mixing head (23) is easy to replace, and is made of an inexpensive and lightweight disposable resin.

  The material that can be handled by the rotary mixer (22) is only required to be able to rotate and stir the Mixing Groter when introduced into the rotary mixer (22) at a minimum. Usually, a material having a viscosity up to about 150,000 mPa · S is sufficiently stirred. can do. Further, the difference in viscosity of the materials to be mixed is not particularly limited as long as a predetermined amount can be reliably supplied into the mixing head (23) since the mixing grotter is rotated and forcibly stirred. On the other hand, in a static type in-tube mixer, it is usually necessary to increase the number of elements as the viscosity difference of the materials to be mixed increases. For this reason, when mixing a high-viscosity material and a small amount of low-viscosity material, the static in-tube mixer has a longer straight pipe part, a larger diameter, and a heavier specification than the rotary mixer (22). .

  What is necessary is just to set suitably the rotation speed of a mixing roaster according to the polymeric resin raw material and polymerization hardening agent to be used. If the rotational speed is set too high, there is a risk that the temperature of the curing agent-containing resin material will increase due to shearing-heat generation due to stirring, so when setting the rotational speed, in addition to checking the mixing state of the curing agent-containing resin material, It is preferable to set the number of rotations by confirming the temperature rise of the resulting curing agent-containing resin material.

  As a method of installing the mixer (22) at the injection port (15), a method in which the mixer (22) can be mechanically attached to the inlet (15), and the mixer (22) is mixed by hand. A method of inserting the nozzle of the vessel (22) into the injection port (15) can be mentioned.

  When the curing agent-containing resin material is injected into the cell (16), the cell (16) can be vibrated in order to improve the filling property of the curing agent-containing resin material in the cell (16). In the case of applying vibration, the vibration can be applied from the start of injection of the curing agent-containing resin material to after the end of injection, or after a while after the start of injection. Further, an auxiliary force such as so-called vacuum assist that sucks air in the cell (16) with a vacuum pump may be used.

  In the manufacturing method of the bathtub of this invention, after inject | pouring a hardening | curing agent containing resin material into a cell (16), the inside of a mixer (22) is substituted by polymerizable resin raw material, and hardening in a mixer (22) is carried out. Can be prevented. With reference to FIG. 3, the operation procedure for replacing the inside of the mixer (22) with the polymerizable resin raw material will be specifically described.

  First, among the polymerizable resin material supply valve (3A) and the polymerization curing agent supply valve (3B) that were opened when the curing agent-containing resin material was injected into the cell (16), the polymerization curing agent supply valve (3B) Is closed after the injection of the curing agent-containing resin material into the cell is completed, and then the polymerizable resin raw material supply pump (22) is supplied to the mixer (which is a rotary mixer in the embodiment shown in FIG. 3). 2A) is started, the curing agent-containing resin material remaining in the mixer (22) is discharged, and the inside of the mixer (22) is replaced with a polymerizable resin raw material. Thus, since the inside of the mixer (22) is filled with the polymerizable resin raw material which does not contain a polymerization curing agent, hardening in the mixer (22) can be prevented.

  When injecting the curing agent-containing resin material into another cell (16) for the production of the next bath, the polymerization curing agent supply valve (3B) is opened, the polymerizable resin material supply pump (2A) and the polymerization curing are performed. The agent supply pump (2B) may be started. In the case of using a rotary mixer as the mixer (22) as in the example of the embodiment shown in FIG. 3, the polymerization curing agent supply valve (3B) is opened, and the rotor is driven by the rotor drive motor (21). It is preferable to start the polymerizable resin raw material supply pump (2A) and the polymerization curing agent supply pump (2B).

  The polymerizable resin raw material remaining in the mixer (22) before starting each of the supply pumps (2A) and (2B) was discharged, and the inside of the mixer (22) was replaced with a curing agent-containing resin material. It is preferable to inject into the cell (16) later. It is possible to start injection of the curing agent-containing resin material into the cell (16) without discharging the polymerizable resin raw material remaining in the mixer (22) from the mixer (22). In the initial stage, the mixing ratio of the polymerizable resin raw material and the polymerization curing agent is not a predetermined ratio. Therefore, if the mixing ratio of the polymerizable resin raw material and the polymerization curing agent of the curing agent-containing resin material to be injected into the cell (16) is to be constant at all times, or the variation in the mixing ratio affects the curing behavior immediately after demolding. If this occurs, it is preferable to adopt a method in which the inside of the mixer is previously replaced with a curing agent-containing resin material and then injected into the cell (16).

  Moreover, the disposal method of waste materials, such as polymeric resin raw material discharged | emitted from the inside of a mixer (22), after discharging a mixer (22) from an inlet (15), it discharges | emits to the waste material container provided separately. It may be processed. Alternatively, the mixer (22) may be discharged to a waste material container provided directly below the female inlet (15) in a state where the mixer (22) is installed at the inlet (15). In this case, care must be taken so that the waste material does not adhere to the female mold (12). Any of these methods can be adopted and may be appropriately selected in consideration of workability and the like.

  The mold that can be used in the present invention may be a mold made of male and female molds (12) and (13), and the thermoplastic resin molded article (11) is not significantly deformed with respect to the injection pressure of the curing agent-containing resin material. In that case, the thermoplastic resin molded article (11) itself may be used as a male mold.

  Molds consist of various materials such as FRP molds using epoxy resin, vinyl ester resin, unsaturated polyester resin, etc., molds made of laminates such as FRP and resin concrete, aluminum alloy molds, cast iron molds, electric molds, etc. A known mold can be used. In particular, the FRP mold is preferable because the mold is easy to manufacture and inexpensive.

  The female mold (12) is provided with an injection port (15) for supplying the curing agent-containing resin material into the cell (16). The installation position and the diameter of the injection port (15) are not particularly limited. What is necessary is just to set suitably according to conditions, such as the magnitude | size of a bathtub, a shape, injection | pouring time of a hardening | curing agent containing resin material. The inlet (15) is usually preferably provided on the side surface or the upper surface of the female mold (12) where the mixer (22) is easily installed.

  The temperature of the female mold (12) is preferably maintained within ± 10 ° C. with respect to the holding temperature of the thermoplastic resin molded article (11) that is heated and held. More preferably, it is maintained at a temperature within ± 5 ° C. When the temperature difference between the mold and the thermoplastic resin molded product (11) is within ± 10 ° C, the time required for curing is stable, and the mold can always be demolded in a constant curing state, and a stable quality bath is stable. There is an advantage that it can be produced with the production amount.

  The surface of the female mold (12) is preferably surface-treated on the side in contact with the curing agent-containing resin material since the surface of the female mold (12) is easily released from the female mold (12) after polymerization curing of the curing agent-containing resin material. . In order to reduce the contact area between the female mold (12) and the curing agent-containing resin material, the surface roughness is preferably 25 μm or less, and more preferably 6.3 μm or less. Further, it is preferable to apply a release agent or laminate with a material that does not adhere to a curing agent-containing resin material such as Teflon (registered trademark). In the present invention, the surface roughness is the maximum height in JIS B0601; Rz.

  When the male mold (13) is used, the male mold (13) is preferably held at a temperature within ± 10 ° C. with respect to the holding temperature of the thermoplastic resin molded article (11). More preferably, it is maintained at a temperature within ± 5 ° C. If the temperature of the male mold (13) is too low, the thermoplastic resin molded article (11) is cooled by the male mold (13), and a long time is required for curing, resulting in a decrease in productivity. If the temperature of the male mold (13) is too high, the thermoplastic resin molded product (11) is likely to be deformed at the portion where it contacts the male mold (13), or the surface is easily damaged.

  The sealing material (14) is a material for sealing the peripheral green part of the cell (16) formed by the thermoplastic resin molded product (11) and the female mold (12). Examples of the sealing material (14) include materials that do not chemically react with the curing agent-containing resin material, such as a fluorine resin, a silicon resin, and an olefin resin. In consideration of reusability, a sealing material (14) made of fluorine resin, silicon resin, or olefin resin is preferable.

  The hardness of the sealing material (14) is not particularly limited as long as it can be easily compressed at the time of clamping, but is preferably 30 or less according to the Japan Rubber Association Standard SRIS-C-0101.

  The cross-sectional shape of the sealing material (14) is not particularly limited as long as it can securely seal the thermoplastic resin molded product (11) and the female die (12), and may be appropriately selected.

The void portion of the cell (16) formed from the female mold (12) and the thermoplastic resin molded article (11) serves as a reinforcing layer for the bathtub.
The thickness of the reinforcing layer may be uniform or non-uniform. What is necessary is just to set to the thickness which satisfies the mechanical strength required for every site | part. However, if the reinforcing layer has a thickness of 2 mm or less, a portion that is not filled with the curing agent-containing resin material may occur. For this reason, when the thickness of the reinforcing layer is 2 mm or less, it is preferable to supply the curing agent-containing resin material into the cell (16) using an auxiliary force such as vacuum assist. In that case, it is necessary to provide a vacuum assist suction hole in the female die separately.

  The curing agent-containing resin material injected into the cell (16) is heated by a male and female mold (12) (13) whose temperature is adjusted to 30 to 90 ° C. to initiate polymerization and curing, and then demolded. The temperature control of the male and female molds (12) and (13) may be performed by appropriately changing the temperature in accordance with the polymerization and curing behavior of the curing agent-containing resin material, or while maintaining the temperature when injected into the cell (16). Good. It is preferable to demold 40 to 60 minutes after injection into the cell (16). After demolding, it is preferable to leave the bathtub with the upper edge portion vertically downward and the bottom portion vertically upward. When the bathtub is allowed to stand in such a direction, it is possible to prevent the four corners of the upper edge portion from dropping vertically downward as the curing progresses, and deviating from the standard management range of the bathtub product.

  Further, in order to suppress deformation at other parts of the upper edge as curing progresses, it is preferable to apply a load over the entire periphery of the upper edge after demolding. Furthermore, it is preferable to perform after-curing in the above-described state. After-curing is usually performed at a temperature of 50 to 70 ° C. for 30 to 90 minutes. Thereby, a bathtub can be hardened completely.

The invention will now be described by way of example with reference to FIGS.
Example 1
A 5 mm-thick methacrylic resin plate (trade name: Acrylite (registered trademark) PX200; manufactured by Mitsubishi Rayon Co., Ltd.) with a deflection temperature under load of 100 ° C. is formed into a bathtub shape by vacuum forming, and a thermoplastic resin molded product ( 11) was prepared.

  100 parts by mass of unsaturated polyester resin (trade name: Iupika 4542P, manufactured by Nippon Iupika Co., Ltd.) and 150 parts by mass of calcium carbonate (product name: NS # 100, manufactured by Nitto Flour & Chemical Co., Ltd.) as a polymerizable resin raw material 2 parts by weight of a mixture of Permec NR and Percure AH (trade name, both manufactured by NOF Corporation) was prepared as a polymerization curing agent. Using a BL type viscometer manufactured by Tokimec Co., Ltd., the viscosity of this polymerization curing agent was about 10 mPa · s measured using adapters NO and 1 at a rotation speed of 60 rpm and a liquid temperature of 20 ° C.

  As the mold, both the female mold (12) and the male mold (13) used were FRP male and female molds made of FRP whose matrix is an epoxy resin. The surface of the female mold (12) that comes into contact with the curing agent-containing resin material is processed to a surface roughness of about 6 μm by finishing with sandpaper # 800, and a release agent (trade name: Diamond Coat EZ-WAY-710, Contents: Synthetic isoparaffin hydrocarbon, aliphatic hydrocarbon, and Franklin Industries, USA) were applied. The mold temperature was kept at 32 ° C. for female and 31 ° C. for male.

The thermoplastic resin molded article (11) was placed on a male mold, and the female mold (12) was spaced about 14 mm from the bottom surface (upward) of the thermoplastic resin molded article (11).
Next, using a silicone sponge string having a sponge hardness of 20 according to the Japan Rubber Association Standard SRIS-C-0101 as a sealant (14) around the thermoplastic resin molded article (11) and the female mold (12), an appropriate mold clamping device is used. Was pressurized and sealed from above and below to form a sealed cell (16).

  In the polymerizable resin material storage tank (1A), 100 parts by mass of unsaturated polyester resin (trade name: Iupica 4542P, manufactured by Nippon Iupika Co., Ltd.) and calcium carbonate (product name: NS # 100 Nitto Powder Co., Ltd.) 150 parts by mass (manufactured by Kogyo Co., Ltd.) were mixed, prepared, heated to 33 ° C. while deaerated, and kept at that temperature. At this time, the viscosity of the polymerizable resin material (BL type viscometer manufactured by Tokimec Co., Ltd .; using adapter No. 2, using a rotation speed of 6 rpm and a liquid temperature of 33 ° C.) was about 2000 mPa · s.

  The polymerizable resin raw material and the polymerization curing agent are a polymerizable resin raw material supply pump (2A) (trade name: sine pump, model: MR-115, manufactured by Tokushu Kika Kogyo Co., Ltd.) and a polymerization hardener supply pump (2B) (product). Name: metering pressure precision gear pump Model: KA1-1.752 made by M & K Co., Ltd.) to each rotary mixer (22) (trade name: power mixer model: WL-501 type M & K Co., Ltd.). This rotary mixer (22) is provided with a disposable polypropylene mixer and a mixing head (23). The discharge rate from the rotary mixer (22) was set to 200 cc / s, and the number of rotations of the Mixin Groter was set to 1000 rpm.

  Hold the rotary mixer (22) in the hand and install the nozzle of the mixing head (23) in the injection port (15) above the injection port (15) of the female mold (12). A curing agent-containing resin material at 33 ° C. obtained by mixing the polymerization curing agent with a rotary mixer (22) was poured into the cell (16).

  After completing the injection of the curing agent-containing resin material into the cell (16), the polymerization curing agent is removed from the injection port (15), removed from the rotary mixer (22), stored in a waste material container, and supplied to the mixing head (23). The supply valve (3B) is closed, the polymerizable resin raw material supply pump (2A) is started, about 100 cc of the waste material is discharged into the waste material container, and the curing agent-containing resin material remaining in the rotary mixer (22) Was replaced with a polymerizable resin raw material.

  When the curing agent-containing resin material is injected into the cell (16) of the next mold, the polymerization curing agent supply valve (3B) is opened, and the polymerizable resin material supply pump (2A) and the polymerization curing agent supply pump ( 2B) and the rotor drive motor (21) of the Mixin Groter are started, about 100 cc of waste material is discharged into a waste material container, and the polymerizable resin material remaining in the rotary mixer (22) contains a curing agent. The resin material was replaced, and the polymerizable resin raw material supply pump (2A) and the polymerization curing agent supply pump (2B) were stopped.

  Injection | pouring of the hardening | curing agent containing resin material to the cell (16) of the following shaping | molding die was performed by the method mentioned above.

After injection into the cell (16), the mold was held for about 50 minutes in a mold temperature-adjusted in advance to the above-described temperature (female mold (12): 32 ° C. male mold (13) 31 ° C.) and then demolded. . The demolded bathtub was loaded with a steel material having a total weight of approximately 10 kg and having a shape in which the upper edge of the bathtub is vertically downward, the bottom is vertically upward, and a load can be applied to the entire periphery of the upper edge. In this state, after-curing was performed at 60 ° C. for 60 minutes in an after-curing furnace to produce a bathtub.
The above-described method was repeated for each molding, and 18 to 20 bathtubs could be manufactured in 8 hours. Neither discharging the curing agent-containing resin material in the mixing head (23) with air nor cleaning the inside of the mixing head with a solvent was performed, but the curing agent-containing resin material in the mixing head (23) Curing did not occur. When the molding operation was completed, the mixing head (23) was discarded, and a new mixing head (23) was mounted at the start of molding the next day, so that the molding operation could be resumed smoothly. Further, since the curing agent-containing resin material is supplied to the inlet (15) with the mixing head (23) installed, molding is performed without interposing a pipe between the inlet (15) and the mixing head (23). I was able to.
(Comparative Example 1)
After the injection of the curing agent-containing resin material into the cell (16) was completed, a bathtub was manufactured in the same manner as in Example 1 except that the inside of the mixing head (23) was not replaced with the raw material of the synthetic resin.
In about 12 minutes until the injection into the next mold cell (16), there is a part where polymerization and curing proceeds in the mixing head (23), and the rotor drive motor ( Since the load was applied to 21), the rotary mixer (22) could not be operated. For this reason, the curing agent-containing resin material could not be injected into the next cell.

  The present invention can be suitably used for forming a resin reinforced bathtub.

It is sectional drawing of the shaping | molding die which installed the thermoplastic resin molded product. It is a schematic diagram which shows the structure of an example of a rotary mixer. It is a figure for demonstrating an example of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mold 11 Thermoplastic resin molded article 12 Female mold 13 Male mold 14 Seal material 15 Inlet 16 Cell 1A Polymerizable resin raw material storage tank 1B Polymerization curing agent storage tank 2A Polymerization resin raw material supply pump 2B Polymerization curing agent supply pump 3A Polymerization Resin raw material supply valve 3B Polymerization curing agent supply valve 21 Rotor drive motor 22 Rotary mixer 23 Mixing head

Claims (4)

A cell is formed by disposing a female mold with a predetermined distance from a thermoplastic resin molded product that has been molded in a predetermined shape in advance, and the peripheral portion of the thermoplastic resin molded product and the peripheral portion of the female mold are sealed. With the mold clamped, the curing agent-containing resin material obtained by mixing the polymerization curing agent and the polymerizable resin raw material with a mixer is injected into the cell from the injection port of the female mold and cured. In the method of manufacturing a bathtub,
A method of manufacturing a bathtub, comprising: injecting the curing agent-containing resin material into the cell from the mixer installed at the inlet of the female mold, and then replacing the inside of the mixer with the polymerizable resin raw material. .   The method for manufacturing a bathtub according to claim 1, wherein the inside of the mixer is replaced with a curing agent-containing resin material in advance when injection into another cell is performed.   The mixer is a rotary mixer provided with a mixing head that houses a rotating body with a plurality of protrusions and channels attached inside a tubular mixer housing with a nozzle attached to the tip. The method for producing a bathtub according to claim 1 or 2. The method for manufacturing a bathtub according to claim 3, wherein the mixing head is a disposable mixing head.

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