JP5162364B2 - Multilayer molded article manufacturing method and multilayer molded article - Google Patents

Description

  The present invention relates to a method for producing a multilayer molded article comprising at least two layers of a resin material, and a multilayer molded article molded by the method. Specifically, a manufacturing method of a core back type multilayer molded product that forms an injection space by moving a movable mold in parallel with a fixed mold, and a multilayer molded product molded by this multilayer molded product manufacturing method About.

  In recent years, there has been a demand for product designs that give different functions to each layer of products in order to increase the added value of products such as higher functionality and design of products, resource saving and environmental measures by recycling and painting. Yes. As a method of forming a multilayer molded product using a plurality of types of resin materials made of different materials, a core back type and a core rotary type are generally used. As a special method, a multilayer such as die slide injection is used. There is a molding method. In the core back type multi-layer molding method (see Patent Document 1), it is only necessary to form a mold with one cavity and one core, so that the mold cost can be reduced compared to other multicolor molding methods. At the same time, the operation of the multicolor molding machine can be simplified.

By the way, in a molded product in which different materials are laminated, warpage may be a problem due to a difference in linear expansion coefficient or molding shrinkage between materials. This warpage is not only due to the difference in material properties, but also due to variations in the thickness of each layer and residual stress generated during molding, etc. is there. Therefore, for example, it has been difficult to obtain a multilayer molded product of a large member such as a bumper, a fender, and a sunroof of an automobile by a conventional method.
As a molding method for obtaining a large molded product, an injection compression molding method (see Patent Document 2) has an advantage of reducing residual stress generated during molding. However, the knowledge about the curvature by the nonuniformity of thickness and the adhesion failure about a large-sized multilayer molded product has not been disclosed until now.
JP 2005-88527 A JP-A-1-264823

  The present invention has been made in view of the above circumstances, and there is no defect such as warpage, the thickness of each layer is uniform, and the method for producing an unprecedented large-scale multilayer molded article having excellent interlayer adhesion, and such good Is to provide a simple molded product.

  As a result of intensive studies to achieve this object, the present inventors have conducted at least one of the steps of injection molding a large multilayer molded article with a mold clamping mechanism at four corners of the mold fixing plate. The present invention finds that the desired good product can be obtained by adjusting the parallelism between the fixed mold and the movable mold and maintaining the parallelism between the molds by injection compression molding. Reached.

  That is, the present invention is (1) a method for producing a multilayer molded article made of at least two layers of resin material, using a fixed mold and a movable mold and injection-molding the first layer by primary molding. A step of moving a movable mold to form a cavity for secondary molding, and a second layer is injection-molded by laminating the first portion by secondary molding to form a first portion and a second portion And a step of forming a multilayer molded product fused with the portion of the mold, and at least one of the injection molding steps includes a fixed mold and a movable mold using a mold clamping mechanism at four corners of the mold fixing plate. It is injection compression molding which maintains the parallelism between metal mold | dies by adjusting the parallelism between these, It is the manufacturing method of the multilayer molded product characterized by the above-mentioned.

In the present invention (2) above injection compression molding, when the movable mold in a mold clamping mechanism of the corners four positions of the mold fixing plate moving parallel to the fixed die, the fixed and the detected movable plate The average distance between the movable mold and the fixed mold is calculated from the detected value of the relative position with the plate, and the difference between the detected value of each mold clamping mechanism and the average distance is corrected to the command value to each mold clamping mechanism. Injection compression molding and / or maintaining the parallelism between the molds by adding and subtracting as a quantity and controlling the integrated value of the difference by feedback

(3) When the above-mentioned injection compression molding is performed by the mold clamping mechanism at the four corners of the mold fixing plate and the movable mold moves parallel to the fixed mold, the mold in the mold clamping mechanism at the four corners is fixed. Detects the clamping force, calculates the average value of the detected clamping force, and calculates the difference between the target clamping force of the clamping mechanism preset to the command value for each clamping mechanism and the average value of the detected clamping force Ru injection compression molding der to maintain the parallelism between the mold by controlling by feedback the integral value of the difference as well as addition and subtraction as a correction amount.

  One of the preferred embodiments of the present invention is that (4) the surface temperature on the cavity side of the first layer is [Tg-20] (° C.) when the glass transition temperature of the resin material used for secondary molding is Tg. It is a manufacturing method of the multilayer molded product in any one of said structure (1)-(3) which is-[Tg + 50] (degreeC).

  One of the preferred embodiments of the present invention is that (5) injection compression molding has a cavity capacity in the intermediate clamping state in a range of 1.1 to 10.0 times the cavity capacity in the final clamping state, and an intermediate A method for producing a multilayer molded article according to any one of the above-mentioned configurations (1) to (4), which is injection compression molding in which the moving speed when the movable mold moves from the mold clamping state to the final mold clamping state is 5 mm / second or more It is.

  One of the preferred embodiments of the present invention is that (6) the thickness of each layer constituting the multilayer molded article is 1 mm to 50 mm, and the thickness (Ta) of each layer constituting the multilayer molded article is the thickness of the thickest part. This is a method for producing a multilayer molded article according to any one of the constitutions (1) to (5), wherein the thickness deviation (Ta / Tb) divided by the thickness (Tb) is 0.7 or more.

  One of the preferred embodiments of the present invention is as follows. (7) The above-mentioned constitutions (1) to (7), wherein the amount of warpage after the multilayer molded article is allowed to stand for 24 hours at 23 ° C. and a relative humidity of 50% is 150 μm / mm or less. A method for producing a multilayer molded article according to any one of (6).

According to a preferred aspect of the present invention, (8) the flow length from the gate to the flow end obtained by the method for producing a multilayer molded article of any one of the above configurations (1) to (7) is 15 to 300 cm. and the maximum projected area is 200～60,000Cm ^2, and the multilayer molded article Ru is provided which is molded using a thermoplastic resin.

According to a preferred embodiment of the present invention, (9) multilayer molded article thermally bending the above configuration (8), removal of the peripheral portion, or a multi-layer molded article obtained by painting Ru are provided.

  According to the present invention, it is possible to obtain a multilayer molded product by injection molding having a thin layer, and further a multilayer molded product which is free from defects such as warpage and excellent in strain and interlayer adhesion. Such molding methods include parts for automobiles such as instrument panels, door panels, back doors, and center consoles, parts for housing equipment such as vanities, bath counters, bathtubs, and bathroom storage panels, buckets and clothes storage cases, etc. It is suitably used in fields that require large-sized products having a multilayer structure, such as the daily necessities field, the home appliance OA equipment field such as TV and personal computer casings, and the industrial effect exerted is extremely great.

  Hereinafter, an embodiment of the present invention will be described in the case of a method for manufacturing a two-layer molded product. The molded product of the present invention is not limited to a two-layer molded product.

(Configuration of molding machine)
FIG. 1 is a longitudinal sectional view of a mold clamping device showing a state at the start of a molding cycle, and FIG. 2 is a longitudinal sectional view of the mold clamping device showing a state before the first layer is injection molded or injection compression molded by primary molding. Fig. 3 is a longitudinal sectional view of a mold clamping device showing a state in which the first layer is injection molded or injection compression molded. Fig. 4 is a view of injection molding or injection compression molding with a mold opened for secondary molding. FIG. 5 is a longitudinal sectional view of the mold clamping device showing a state where preparation is performed, FIG. 5 is a longitudinal sectional view of the mold clamping device showing a state where the second layer is subjected to injection molding or injection compression molding, and FIG. It is a longitudinal cross-sectional view of the mold clamping device showing a state where the two-layer molded product is taken out.

The mold clamping device 10 constitutes an injection molding machine together with the first injection device 11 and the second injection device 12. The mold clamping device 10 includes a fixed plate 21 that is a mold fixing plate for mounting the fixed mold 13, a movable plate 22 that is a mold fixing plate facing the fixed plate 21 for mounting the movable mold 14, and corners of the movable plate 22. A clamping mechanism 16 comprising a hydraulic cylinder device or the like provided in the vicinity of the four corners and having a clamping chamber 27 and an opening chamber 28; a tie bar 23 formed by extending a rod of the hydraulic cylinder device of the clamping mechanism 16; The engaging device 20 provided at the four corners of the fixing plate 21 on the extension of 23 and provided at the opening of the through hole passing through the fixing plate 21 side end of the tie bar 23, the upper and lower surfaces or the front and back surfaces of the fixing plate 21 A pair of side surfaces are provided, and a mold opening / closing device 18 including a hydraulic cylinder device or a servo motor and a ball screw mechanism that moves the movable plate 22 toward and away from the fixed plate 21, and a fixed plate 21 and a support plate 26. Established Composed of a position sensor 24 that slides id 25 above. The position sensor 24 is attached in the vicinity of each mold clamping mechanism 16 of the movable plate 22 so that the distance of the movable plate 22 to the fixed plate 21 at each corner can be detected. The mold clamping mechanism 16 may be provided on any mold fixing plate of the fixed plate 21 and the movable plate 22.
A mold device 15 is configured by the fixed mold 13 and the movable mold 14. And the position sensor 24 may be attached to the fixed mold 13 and the movable mold 14 at four locations.

  As an arrangement method of the first injection device 11 and the second injection device 12 in the injection molding machine, for example, a method in which two injection devices are arranged horizontally in parallel, or one injection device is set up vertically and the other is arranged horizontally. Although the method of arrange | positioning, the method of arrange | positioning two injection apparatuses horizontally and orthogonally, etc. are mentioned, Any method can be used in this invention. In addition, each of the injection devices can be molded by setting independent molding conditions.

  The resin flow path in the mold uses a method of injecting resin from multiple injection devices and filling the cavity through an independent hot runner manifold and each gate, as well as a method of filling the cavity through a cold runner. be able to. Here, as a hot runner gate system, any of an internal heating method, an external heating method, etc. may be used, and in the case of an external heating method, any of an open gate method, a hot edge gate method, a valve gate method, etc. Although it can be used, the valve gate method is preferable from the viewpoint of obtaining a wider range of molding conditions. When using a hot runner of the valve gate type, a packing member is used to prevent the molten thermoplastic resin from leaking from the sliding portion of the valve gate. Specific examples of the material constituting the packing member include acrylic rubber, silicone rubber, ethylene-propylene rubber, nitrile rubber, and fluorine-based resin. Silicone rubber is excellent in heat resistance. In addition, a fluorine-based resin is preferable.

(Cavity formation for primary molding)
Next, a molding example of a two-layer molded product will be described in the order of steps with reference to FIGS. Here, the case where both primary molding and secondary molding are injection compression molded is shown. In FIG. 1, it is in the state at the start of the molding cycle. In FIG. 2, the mold is closed by the mold opening / closing device 18 and the tie bar 23 and the fixed plate 21 are coupled by the lock device provided on the fixed plate 21. The intermediate clamping state is opened by an amount corresponding to the compression stroke, which is the difference between the state and the final clamping state, and is the starting point of the molding cycle. Here, the injection process refers to a process from when the molten resin is filled into the mold cavity corresponding to the product until the supply of the resin filled into the cavity is completed.

The width of the compression stroke in the intermediate clamping state is such that the cavity capacity in the intermediate clamping state is preferably 1.1 to 10.0 times the cavity capacity in the final clamping state, more preferably 1.2 to 9.0. It is set to be in the range of double, more preferably in the range of 1.5 to 8.0. Since the width of the compression stroke in the intermediate mold clamping state is widened as described above, the injection rate can be reduced, the distortion of the molded product can be improved, and the injection device 11 is also the cost of the high-speed and high-pressure injection type. It is not necessary to use a high injection device. When the cavity capacity in the intermediate clamping state is less than 1.1 times the cavity capacity in the final clamping state, high pressure is concentrated on the resin near the gate when the resin is filled in the cavity in the injection process. The distortion and thickness variation of the molded product are likely to occur, and if it exceeds 10.0 times, molding defects such as jetting are likely to occur.
The stop position of the movable mold 14 in the intermediate mold clamping state is that the final mold clamping is performed without setting the intermediate mold clamping state that is excessively opened by the compression stroke when the thickness of each layer of the molded product is a certain thickness or more. It is good also as a position which moved movable mold 14 to the process. Then, the movable die 14 is retracted by receiving the injection pressure in the injection step, and the volume of the cavity is enlarged, so that the subsequent compression stroke is ensured, whereby the injection compression molding can be performed.

(Injection process and compression process of primary molding)
In FIG. 3, the molten resin is injected from the first injection device 11 into the cavity formed in FIG. 2. This step is an injection step, and the compression step is performed next as a continuous step or a step in which the latter half and a part of the injection step are continued in parallel. When the compression process is started in the latter half of the injection process, the screw advance position is detected, and when the screw advance position reaches the set position, compression by the mold clamping mechanism is started. The compression process is performed by compressing the molten material injected in the injection process so that the volume of the cavity is reduced by each mold clamping mechanism 16, and filling the cavity by spreading the molten material in the cavity. Then, the first layer 31 is formed.

(Injection rate of molten resin in the injection process)
In the injection step, the injection rate of a molten resin is injected from the first injection unit 11 into the cavity formed in FIG. 2 is preferably 50~2,000cm ³ / sec, more preferably 100~1,800cm ³ / sec 150-1500 cm ³ / sec is more preferable. When the injection rate is less than 50 cm ³ / sec, the time for filling the cavity with the molten resin becomes longer, and the resin temperature decreases and the melt viscosity becomes too high before the transition from the injection process to the compression process. In the process, it tends to cause appearance defects such as short shots and flow marks, and poor accuracy in thickness and dimensions. On the other hand, when the injection rate exceeds 2,000 cm ³ / sec, distortion tends to remain in the obtained molded product, and appearance defects such as silver streaks due to air entrainment tend to occur. The injection rate referred to here is the resin volume injected into the mold cavity divided by the time required from the start of injection to the end of injection, and does not necessarily have to be a constant speed.

(Parallel control between molds in the compression process)
In the compression step, the parallelism between the molds is maintained by adjusting the parallelism between the fixed mold and the movable mold with a mold clamping mechanism at four corners of the mold fixing plate. An average distance between the movable mold 14 and the fixed mold 13 is calculated from the detected value of the relative position between the movable plate 22 and the fixed plate 21 detected by the position sensor 24, and a command value to each mold clamping mechanism 16 is calculated. By adding and subtracting the difference between the detected value of each mold clamping mechanism and the average distance as a correction amount and feeding back and controlling the integral value of the difference, the parallelism between the movable mold 14 and the fixed mold 13 is increased. It is preferred to use a method of maintaining. As a result, the molten material flows uniformly and at high speed in the cavity, so that the first layer 31 has low distortion as an effect of compression molding, and a uniform and high accuracy as a parallel control effect.

  Further, in the compression step, the parallelism between the molds is not maintained based on the detected value of the relative position between the movable plate 22 and the fixed plate 21 by the position sensor 24, but the movable molds are moved by the mold clamping mechanisms 16. When the mold 14 moves in parallel with respect to the fixed mold 13, the mold clamping force in each mold clamping mechanism 16 is detected, the average value of the detected mold clamping forces is calculated, and the command value to each mold clamping mechanism 16 is calculated. The degree of parallelism between the molds is controlled by adding and subtracting the difference between the target clamping force of the mold clamping mechanism set in advance and the average value of the detected clamping force as a correction amount and feeding back the integrated value of the difference. It is also preferred to use a method of maintaining. Furthermore, it is also preferable to use both in combination in order to control the parallelism between the molds with higher accuracy. When both position control and mold clamping force control (pressure control) are used together, the average distance between the movable mold 14 and the fixed mold 13 advances from the intermediate mold clamping position to a predetermined distance, or The parallel control based on the position control may be performed until the average value of the detected clamping force reaches a predetermined pressure, and the pressure control may be performed after a predetermined distance or a predetermined pressure is detected. Further, after performing parallel control by position control, position control and pressure control may be used simultaneously. When the position control and the pressure control are used simultaneously, the position control is used only for the feedback control, and the pressure control performs at least one of the feedback control and the feedforward control.

In the case where only position control is performed, the average distance between the movable mold 14 and the fixed mold 13 is calculated from the detected value of the relative position between the movable plate 22 and the fixed plate 21 detected by the position sensor 24. In addition to adding and subtracting the difference between the detected value of each mold clamping mechanism and the average distance as a correction amount to the command value to each mold clamping mechanism 16 and feeding back and controlling the integrated value of the difference, each mold clamping Feed forward control may be added to the mechanism 16 to perform mold clamping with emphasis on speed while maintaining parallelism between the movable mold 14 and the fixed mold 13.
In the compression step, in order to maintain the parallelism between the molds by adjusting the parallelism between the fixed mold and the movable mold with the mold clamping mechanisms at the four corners of the mold fixing plate, It is also preferable to use a master slave method in which the mold clamping mechanism at one part is the master and the rest is the slave, but especially in the case of large multilayer molded products that require more accurate parallel control than the master slave method. Also, the above two methods are more preferable.

  In the compression process of the present invention, particularly when a large-scale multilayer molded product is formed, maintaining the degree of parallelism between the molds from the intermediate clamping state and the intermediate clamping state to the final clamping state is important. In order to obtain a large-scale multilayer molded product, there are many cases where molding is performed by attaching a heavy metal mold to the movable plate 22 and the fixed plate 21, and each mold of the molding machine is increased as the mold weight increases. It is difficult to maintain parallelism in the fastening mechanism 16. In addition, the uneven load generated by the pressure at the time of filling the resin also causes the thickness non-uniformity of the molded product, but this effect is particularly noticeable in large multilayer molded products. Furthermore, maintaining parallelism between molds achieves a more uniform pressure load on the resin within the mold. As a result, the pressure applied to the resin achieves a low pressure as a whole, and it is possible to provide a molded product with less distortion. When the parallelism between the molds is not sufficient, a local difference is generated in the pressure applied to the multilayer molded product during molding, which becomes one of the causes of distortion and also causes the warpage of the multilayer molded product. Further, from the viewpoint of productivity, the misalignment of parallelism causes mold galling and the like, making it difficult to mass-produce products.

(Movement speed of movable mold in compression process)
In the compression step, each mold clamping mechanism 16 compresses the volume of the cavity so as to reduce the volume, and the moving speed of the movable mold when filling the cavity by spreading the molten material in the cavity is 5 mm / second. The above is preferable, 7.5 mm / second or more is more preferable, and 10 mm / second or more is still more preferable. A molded article having a higher L / D requires a higher mold capacity enlargement ratio and requires a higher moving speed. This is because in order to reduce the distortion of the molded product, it is important to end the compression process up to a predetermined final clamping state while the thermal distribution of the molten resin in the cavity is narrow. The higher the moving speed, the larger the compression stroke can be handled. Therefore, it is preferable that the moving speed is as high as possible, but at present, about 40 mm / sec is practically a limit on the apparatus. If the level is 35 mm / second, sufficiently precise speed control is possible. The moving speed is obtained by dividing the compression stroke from the intermediate clamping state to the final clamping state by the time required for compression, and does not necessarily have to be a constant speed. As described above, the larger the compression stroke and the higher the moving speed of the mold, the easier the galling of the mold occurs. Therefore, maintaining the parallelism between the molds is also an important and essential condition here.

(Pressurization process of primary molding)
In the compression step, the mold clamping mechanism 16 compresses the cavity to reduce the volume, and fills the cavity by spreading the molten material in the cavity, whereby the repulsive force of the resin rises rapidly. At this time, the control by the mold clamping mechanism 16 may be switched from the position control to the pressure control. When switching to pressure control, it is desirable to control the pressure in the cavity (surface pressure) to be 7 to 20 MPa. Usually, the hydraulic pressure of the hydraulic cylinder or its piping is detected, and the surface pressure is obtained by dividing the mold clamping force by the projected area of the molded product, but a resin pressure sensor may be provided in the cavity.

  In order to maintain the cavity capacity in the final clamping state with an appropriate pressure that overcomes the repulsive force, the process is continued as a process that has continued in the compression process, or a process that has continued in parallel with the latter half of the compression process. A pressure process is performed. By this pressure-holding step, a very appropriate amount of resin is filled with a uniform density by the injection device 11 in the target multilayer molded article volume, and the multilayer molded article becomes a preferable one with very little warpage and distortion. The application of pressure to the resin (pressurization) is due to the force by which the movable mold advances by each mold clamping mechanism 16. Further, such pressure transmission is usually performed by direct contact between these advancing members and the resin, but pressure transmission media such as fluid may be interposed between them.

The appropriate holding time of the pressure depends on the thickness of the molded product, and the appropriate time becomes longer as the thickness increases. However, this tendency is particularly noticeable in the case of a large molded product. In the case of a large molded product intended by the present invention, the holding time X (seconds) when the molded product thickness is t (mm) is appropriately within the range satisfying the following formula (I). For example, in the thickness of 25 mm which is an intermediate value in the range of 1 mm to 50 mm which is the thickness of each layer suitable in the present invention, the range of 760 ± 30 seconds is preferable. However, this does not apply when a system that rapidly heats and cools the mold temperature typified by the heat and cool molding method is used.
X = (30 × t + 10) ± 30 (seconds) (I)

(Cooling process of primary molding)
Subsequent to the pressure holding step, a cooling step of primary molding may be performed. In this cooling step, the surface temperature on the cavity side of the first layer 31 is preferably [Tg−20] (° C.) to [Tg + 50] (Tg is the glass transition temperature of the resin material used for the secondary molding. ° C.), more preferably, cooling is performed until the temperature reaches [Tg-10] (° C.) to [Tg + 45] (° C.). In addition, the glass transition temperature here is measured by the method prescribed | regulated to JISK7121, and means the glass transition temperature which can be recognized in charts, such as DSC. In addition, when the resin material used in the secondary molding is composed of two or more kinds of resins, when it shows two or more glass transition temperatures, it indicates the highest temperature, while the resin is a single kind of glass. If there is only one transition temperature, this is the temperature.
When secondary molding is performed with the surface temperature on the cavity side of the first layer 31 under the above conditions, the resin material used for the secondary molding is insulated from the movable mold 14 by the first layer molded product 31. Even if the second layer 32 in FIG. 4 is thin, the formation of the solidified layer of the resin is delayed, and the flow resistance of the resin is lowered to improve the thin-wall moldability. In addition, the interface temperature between the first layer 31 and the second layer 32 becomes sufficiently high when the heat of the resin is heated, thereby improving the adhesion of the interface.

  However, since it is not preferable to set the surface temperature on the cavity side of the first layer 31 so as to exceed the heat resistance of the first layer 31, the surface temperature is 10 ° C. or more lower than the glass transition temperature of the first layer 31. It is preferable to do. More preferably, the temperature is 20 ° C. or more lower than the glass transition temperature. During the cooling process, the pressure in the pressure-holding process may be maintained, in a state where no pressure is applied, or further, the pressure may be lowered stepwise during the cooling process. Further, since the position control or the pressure control is performed by the mold clamping mechanism 16 during the cooling process, the sink can be prevented even if the thickness of the molded product is about 20 mm to 50 mm and the sink is likely to occur. it can.

(Cavity formation for secondary molding)
In FIG. 4, the supply of pressure oil to the clamping chamber 27 of each mold clamping mechanism 16 is stopped and the pressure is released, and pressure oil is supplied to the open chamber 28 to separate the movable plate 22 from the fixed plate 21. The process of forming the cavity for secondary molding is shown. As a result, the movable mold 14 is separated from the fixed mold 13 by a predetermined distance, and the volume of the cavity is expanded again. At this time, it is preferable that the movement of the movable mold 14 is performed in parallel with the mold-matching surfaces of the movable mold 14 and the fixed mold 13 in order to satisfactorily perform the compression process of the secondary molding. Also in such parallel control, it is preferable to use a method of maintaining parallelism between molds used in the compression process.
In the secondary molding cavity as well as in the primary molding cavity, the movable mold 14 is opened by an amount corresponding to the compression stroke that is the difference between the intermediate mold clamping state and the final mold clamping state in the injection process. It is in an intermediate mold clamping state. The width of the compression stroke in the intermediate clamping state is such that the cavity capacity in the intermediate clamping state is in the range of 1.1 to 10.0 times the cavity capacity in the final clamping state, more preferably 1.2 to 9.0 times. It sets so that it may become the range, More preferably, the range of 1.5-8.0.

  In this embodiment, a cavity for secondary molding is formed between the fixed mold 13 and the first layer 31. However, the first mold 31 is left on the fixed mold 13 side, and the movable mold 14 and the first layer 31 are left. A cavity for secondary molding may be formed between the two. In that case, the second injection device 12 may be provided on the back side of the movable plate 22. In that case, the movable plate 22 is provided with a hole into which the second injection device 12 can be inserted in the same manner as the fixed plate 21. Furthermore, as a method of forming a cavity for secondary molding, a cavity for secondary molding may be formed by moving some blocks of the mold as the movable mold 14 is moved.

(Secondary molding)
In FIG. 5, the molten resin is injected from the second injection device 12 into the cavity formed in FIG. This step is a secondary molding injection step, and the compression step and the pressure holding step of the second layer 32 are performed by the same operation as in FIG. In this process, it is necessary to use a method for maintaining the parallelism between the molds used in the compression process of the primary molding.
In the cooling step in the secondary molding, the first layer 31 and the second layer 32 are cooled until the two-layer molded product 33 in FIG. Normally, it can be said that it can be taken out if it is below the deflection temperature under load, but in the case of a large molded product, it may be bent due to its own weight, so it is preferable to take it out at a temperature lower by 30 to 60 ° C. than the deflection temperature under load. . The deflection temperature under load here is measured by the method defined in JIS K7191-1 / 2, and is not measured when the first layer alone or the second layer alone, The deflection temperature under load of the entire two-layer molded product 33 is represented. During the cooling process, the pressure in the pressure-holding process may be kept, may be in a state where no pressure is applied, or may be lowered stepwise during the cooling process.

(Two-layer molded product removal process)
In FIG. 6, the supply of pressure oil to the clamping chamber 27 of the mold clamping mechanism 16 is stopped, the pressure is released, the pressure oil is supplied to the release chamber 28, and the molded product is released from the mold. 18 is used to open the movable plate 22 to a predetermined position. Then, after the movable plate 22 stops at a predetermined position, the two-layer molded product 33 is protruded from the movable mold 14 by an ejector device (not shown) provided on the movable plate 22 and the two-layer molded product 33 is taken out.
After the removal process of the two-layer molded product 33 is completed, the movable mold 14 is movable so as to be in an intermediate mold clamping state that is opened by an amount corresponding to a compression stroke that is a difference between the intermediate mold clamping condition and the final mold clamping condition. The plate 22 moves forward relative to the fixed plate 21 and continues to FIG. 2 which is a state before the start of the next primary molding.

(Thickness of each layer)
In the method for producing a multilayer molded article of the present invention, various molded articles can be produced, but preferably, the multilayer molded article is applied to a multilayer molded article in which the thickness of each layer constituting the multilayer molded article is 1 to 50 mm. Is preferred. This is because a multilayer molded article having such a thickness can effectively utilize the advantages of injection compression molding. Further, it is more preferable to apply to a multilayer molded product in which the thickness of each layer constituting the multilayer molded product is 2 to 45 mm, more preferably the thickness of each layer constituting the multilayer molded product is 3 to 40 mm. In addition, 2-150 mm is preferable as the whole multilayer molded product obtained from the manufacturing method of the multilayer molded product of this invention, 2-135 mm is more preferable, 2-120 mm is further more preferable.

When the thickness of each layer is less than 1 mm, the flow resistance of the molten resin is remarkably increased in the large molded product that is the subject of the present invention, and therefore, uneven pressure is applied to the multilayer molded product in the injection process and the compression process, causing warping. It becomes extremely difficult to suppress such deformation and distortion. If it is larger than 50 mm, it takes a long time to reach the temperature at which the multilayer molded product can be taken out in the cooling process, which not only significantly reduces productivity, but also controls shrinkage in the thickness direction of the molded product as it cools, so-called sink marks. The thickness uniformity of each layer of the multilayer molded product intended by the present invention is impaired.
In addition, the thickness of each layer here refers to a cross-section of the obtained multilayer molded product cut out with a band saw or the like, and the thickness of each layer is measured at 10 or more locations with a caliper or the like to calculate an average value.

(Thickness uniformity of multilayer molded products)
The multilayer molded product obtained by the present invention preferably has a thickness deviation (Ta / Tb) obtained by dividing the thickness (Ta) of the thinnest part in each layer constituting the multilayer molded product by the thickness (Tb) of the thickest part. 0.7 or more, more preferably 0.75 or more. In order to obtain a multilayer molded article having a large thickness such as an automobile bumper, fender, sunroof, etc. having such thickness uniformity, a fixed mold is formed by a mold clamping mechanism at four corners of the mold fixing plate of the present invention. The advantage of the injection compression molding method that maintains the parallelism between the molds by adjusting the parallelism between the mold and the movable mold is extremely effective. The thickness deviation as an index representing the thickness uniformity is 1 when the thickness deviation is 1 and the thickness of each layer is completely uniform. The closer to 1, the better the quality as a multilayer molded product. In addition, when the uneven thickness is less than 0.7, the influence of deformation and distortion such as warpage resulting from thickness variation is increased, and the dimensional accuracy of the multilayer molded product is significantly impaired.
In addition, the thickness of the thinnest part in each layer here and the thickness of the thickest part are a section of the obtained multilayer molded product cut out with a band saw or the like, and the thickness of each layer measured with 10 or more calipers or the like is defined as the population The thickness of the thinnest part and the thickest part in each layer extracted from the inside is expressed.

(War amount of multilayer molded product)
The multilayer molded product obtained by the present invention preferably has a warp amount of 150 μm / mm or less, more preferably 125 μm / mm or less after the multilayer molded product is allowed to stand for 24 hours at 23 ° C. and 50% relative humidity. It has stability. In order to obtain a multi-layer molded product of large members such as automobile bumpers, fenders, sunroofs and the like having such dimensional stability, a fixed mold is formed by a mold clamping mechanism at four corners of the mold fixing plate of the present invention. The advantage of the injection compression molding method that maintains the parallelism between the molds by adjusting the parallelism between the mold and the movable mold is extremely effective. When the amount of warpage exceeds 150 μm / mm, the dimensional accuracy of the multilayer molded product is greatly impaired, and when the amount of warpage exceeds 200 μm / mm, a load is applied to the interface between the layers due to the warpage. It leads to a decrease in adhesion.
The amount of warping after the multilayer molded product is left to stand for 24 hours under the conditions of 23 ° C. and 50% relative humidity is the plate thickness after the multilayer molded product is allowed to stand for 24 hours under the constant temperature and humidity. Molding was obtained by measuring the height of the gate side edge with a vernier caliper and fixing the flow end side edge of the multilayer molded product to the surface plate so that the molded product does not break. This is the amount of warpage of the product. Note that the width of the flow-end side edge of the multilayer molded product in close contact with the surface plate using a plate-shaped jig is the length from the flow end edge to the gate-side edge to the gate. The width is such that 20% is in close contact with the side edge direction.

(Resin material)
As the resin material that can be used in the molding method of the present invention, a thermoplastic resin is preferably used. Examples of the thermoplastic resin include general-purpose plastics represented by polyethylene resin, polypropylene resin, polystyrene resin, polyacrylstyrene resin, ABS resin, AS resin, AES resin, ASA resin, SMA resin, polyalkyl methacrylate resin, and the like. Engineering plastics such as polyphenyl ether resin, polyacetal resin, polycarbonate resin, polyalkylene terephthalate resin, polyamide resin, cyclic polyolefin resin, polyarylate resin (amorphous polyarylate, liquid crystalline polyarylate), polyether ether Various thermoplastic polyimides represented by ketones, polyetherimides, polyamideimides, etc., so-called polysulfone, polyethersulfone, polyphenylene sulfide, etc. Or the like can be used over par engineering plastics. Furthermore, thermoplastic elastomers represented by styrene thermoplastic elastomer, olefin thermoplastic elastomer, polyamide thermoplastic elastomer, polyester thermoplastic elastomer, polyurethane thermoplastic elastomer, foamed polycarbonate, foamed polyurethane, foamed polystyrene, foamed polypropylene. A foamable thermoplastic resin typified by, etc. can also be used. Any of these thermoplastic resins can be used for each layer constituting the multilayer molded product such as the first layer and the second layer and other portions.
Here, the other part means, for example, a polycarbonate resin plate-shaped molded product as a resin molded product forming the first layer, and a thermoplastic elastomer such as a polyester-based elastomer around it using a multicolor molding method. When the polymethylmethacrylate resin layer is formed on the polycarbonate resin layer using the molding method of the present invention after that, the one corresponding to the thermoplastic elastomer portion not related to the layer structure is said. .

  As the resin material of the present invention, the above thermoplastic resins can be appropriately selected and mixed according to the purpose of use of the multilayer molded product. Further, the resin material of the present invention includes conventional additives such as heat stabilizers, mold release agents, infrared absorbers, ultraviolet absorbers, antioxidants, light stabilizers, foaming agents, reinforcing agents (talc, mica, clay , Wollastonite, calcium carbonate, glass fiber, glass bead, glass balloon, milled fiber, glass flake, carbon fiber, carbon flake, carbon bead, carbon milled fiber, metal flake, metal fiber, metal coated glass fiber, metal coated carbon Fiber, metal coated glass flakes, silica, ceramic particles, ceramic fibers, aramid particles, aramid fibers, polyarylate fibers, graphite, conductive carbon black, various whiskers, etc.), flame retardant (halogen, phosphate ester, metal salt) , Red phosphorus, silicon, fluorine, metal hydrate, etc.), wear Agents (pigments and dyes such as carbon black and titanium oxide), light diffusion agents (acrylic crosslinked particles, silicon crosslinked particles, ultrathin glass flakes, calcium carbonate particles, etc.), fluorescent brighteners, phosphorescent pigments, fluorescent dyes, antistatic agents Blending agent, flow modifier, crystal nucleating agent, inorganic and organic antibacterial agent, photocatalytic antifouling agent (fine particle titanium oxide, fine particle zinc oxide, etc.), impact modifier represented by graft rubber, and photochromic agent be able to.

Among these, in the present invention, it is preferable to use, for the first layer, a thermoplastic resin that is particularly excellent in appearance, mechanical strength, and heat resistance, and that has excellent scratch resistance and solvent resistance. Examples of such a thermoplastic resin include a polycarbonate resin alone and a mixture of a polycarbonate resin and a polyester resin, but a mixture of a polycarbonate resin and a polyester resin is more preferable from the viewpoint of excellent solvent resistance. The production method and characteristics of such a thermoplastic resin are described in detail in, for example, Japanese Patent Application Laid-Open Nos. 2007-23118 and 2002-265769.
In the present invention, it is preferable to use a thermoplastic resin excellent in shock absorption for the second layer. Examples of such thermoplastic resins include foamable thermoplastic resins such as foamed polycarbonate, foamed polyurethane, foamed polystyrene, and foamed polypropylene, styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and polyester-based thermoplastics. Examples of thermoplastic elastomers include thermoplastic elastomers and polyurethane-based thermoplastic elastomers. From the viewpoint that good adhesion to the thermoplastic resin used in the first layer is expected, expanded polystyrene and polyester-based thermoplastic elastomers are used. A polyester-based thermoplastic elastomer is more preferable. The production method and characteristics of such a polyester-based thermoplastic elastomer are described in detail, for example, in JP-A-10-330605.

(Multilayer molded product)
Here, the multilayer molded product molded by the mold apparatus 15 will be described. The multilayer molded article in the production method of the present invention preferably has a flow length from the gate to the flow end of 15 to 300 cm and a maximum projected area of 200 to 60,000 cm ² . Provided is a multilayer molded article having little warpage and excellent adhesion in the molded article. A multilayer molded article more suitable for exhibiting the effects of the present invention is a multilayer molded article having a flow length from the gate to the flow end of 30 to 250 cm and a maximum projected area of 1,000 to 40,000 cm ^2. It is.

(Secondary processing of multilayer molded products)
The multilayer molded product of the present invention may be formed into a predetermined shape by performing a secondary processing step typified by thermal bending or peripheral edge removal after molding.
The method of heat bending is not particularly limited, and as such a method, using a mold, a wooden mold or a resin mold that has been dug into a desired shape in advance, in a heating environment (generally, An example is a method of shaping the multilayer molded article using the mold or the like under pressure or under reduced pressure (under vacuum) under a temperature near the glass transition temperature of the synthetic resin substrate.
Further, the method for removing the peripheral portion is not particularly limited, and any of a cutting method, a cutting method, and a punching method can be used as the method. Examples of the cutting method include a method of cutting with an NC lathe, a milling machine, a machining center, or the like using various cutting tools such as a router, an end mill, a milling cutter, and a rotary tool. In the cutting method, cutting with a blade, cutting with abrasive grains, shear cutting, cutting by heating / melting, electric discharge cutting, and the like can be used. Among the above, the apparatus is widely used, and the cutting method is preferable in terms of excellent cutting accuracy and speed. The cutting may be performed by any method of complete dry cutting, wet cutting, and semi-dry cutting.

(Surface decoration on multilayer molded products)
The multilayer molded article of the present invention can be provided with various functional layers including a colored layer and a hard coat layer on the surface thereof. Such functional layers include design layers, conductive layers (heat generation layers, electromagnetic wave absorption layers, antistatic layers), water and oil repellent layers, hydrophilic layers, ultraviolet absorption layers, infrared absorption layers, crack prevention layers, and metal layers (metabolites). Rising layer) and the like are exemplified. These functional layers include the surface of the hard coat layer, the surface of the molded article opposite to the hard coat layer, the layers between the layers constituting the multilayer molded article, a part between the primer layer and the molded article surface, and the primer layer. It can be provided in a part between the top layer of the hard coat and the like.
In the above, the design layer is usually formed by printing. As the printing method, conventionally known printing methods such as gravure printing, flat printing, flexographic printing, dry offset printing, pad printing, and screen printing can be used according to the product shape and printing application.

  As the composition of the printing ink used in printing, it is possible to use a resin system and an oil system as main components. As the resin system, natural resins such as rosin, gilsonite, shellac, and copal, phenolic systems and their Derivatives, amino resins, butylated urea, melamine resins, polyester alkyd resins, styrene resins, acrylic resins, phenol resins, epoxy resins, polyamide resins, polycarbonate resins, saturated polyester resins, amorphous polyarylate resins, amorphous Synthetic resins such as polyolefin resin, vinyl chloride resin, vinyl acetate resin, vinyl chloride-vinyl acetate copolymer, butyral resin, methyl cellulose resin, ethyl cellulose resin, and urethane resin can be used. When an ink component having high heat resistance is required, a printing ink using a polycarbonate resin, an amorphous polyarylate resin, or the like as a binder is preferable. The printing ink can be adjusted to a desired color with a pigment or dye.

  Hereinafter, the present invention and the effects thereof will be further described using examples and comparative examples, but the present invention is not limited to these examples.

(1) Thickness: A cross section (37) from the vicinity of the gate side to the vicinity of the flow end side of the multilayer molded product (length 1,800 mm) having the shape shown in FIG. The thickness of each layer was measured with calipers at intervals of 120 mm toward the surface, and the average value thereof was calculated.
(2) Uneven thickness: The thickness (Ta) and thickness of the thinnest part in each layer, where the thicknesses of the 16 layers measured to determine the average thickness of each layer of the multilayer molded product are used as a population. The thickness (Tb) was extracted, and the thickness (Ta) of the thinnest part was divided by the thickness (Tb) of the thickest part to determine the thickness deviation (Ta / Tb) of each layer. It should be noted that the thickness of each layer is completely uniform when the uneven thickness = 1.
(3) Warpage amount of the multilayer molded product: After allowing the multilayer molded product having the shape shown in FIG. 7 to stand at 23 ° C. and a relative humidity of 50% for 24 hours, a multilayer molded product using a plate-shaped jig is used. The flow end side edge (40) was fixed in close contact with the surface plate, and the height of the gate side edge (41) was measured with a caliper to determine the amount of warpage of the molded product. Note that the width of the flow-end side edge of the multilayer molded product in close contact with the surface plate using a plate-shaped jig is the length from the flow end edge to the gate-side edge to the gate. The width is such that 20% is in close contact with the side edge direction.
(4) Interlayer adhesion of multilayer molded product: A test piece (42) having a length of 150 mm and a width of 150 mm was cut out from the multilayer molded product having the shape shown in FIG. 7, and MIL- using TSA-101L manufactured by Espec Co., Ltd. Thermal shock evaluation was performed according to STD-202G-A. The test piece was taken out every 10 cycles, and the presence or absence of delamination was visually evaluated.
○: No delamination was observed at the 100th cycle.
Δ: Delamination was observed between the 50th and 90th cycles.
X: Delamination was recognized by 40th cycle.

[Example 1]
A two-layer molded product was molded according to the following steps.
PC / PET alloy resin pellets were dried at 110 ° C. for 5 hours as the resin material of the first layer used in the primary molding. Further, TPE resin pellets were dried at 80 ° C. for 5 hours as a second layer resin material used for secondary molding. These two types of resin materials are injection press-molded using a large molding machine (manufactured by Meiki Seisakusho Co., Ltd .: MDIP2100, maximum clamping force 33540 kN) equipped with a 4-axis parallel control mechanism. A large multilayer molded product having a thickness of 9.8 mm (first layer: 7.0 mm, second layer: 2.8 mm), a length of 1,800 mm (including the gate portion (35), 1,940 mm), and a width of 1,200 mm Manufactured. Such a molding machine is equipped with a hopper dryer facility capable of separately drying two kinds of resin raw materials, and the dried pellets are supplied to the molding machine supply port by pneumatic transportation and used for molding. The runner was a valve gate type hot runner (diameter 8 mmφ) manufactured by HOTSYS.

The molding conditions of the primary molding are the cylinder temperature of the first injection device 290 ° C, the hot runner set temperature 290 ° C, the mold temperature is 80 ° C on the movable side, 70 ° C on the fixed side, injection rate 660 cm ³ / sec, compression stroke 21.0 mm The moving speed of the mold from the intermediate clamping state to the final clamping state was 10 mm / second, and the pressure holding time was 220 seconds. Mold compression was started immediately before completion of filling, and the overlap was 0.5 seconds. Immediately after completion of filling, the valve gate was closed so that the molten resin did not flow backward from the gate to the cylinder. The pressure during the compression step was 17.2 MPa, and the pressure during the pressure holding step was maintained at half the pressure. The movable mold parting surface was not in contact with the fixed mold parting surface in the final advanced position. The cavity capacity in the intermediate clamping state under such molding conditions was 4.0 times the cavity capacity in the final clamping state. Under such molding conditions, the surface temperature on the cavity side of the first layer could be lowered to the target temperature of 90 ° C. in the pressure-holding step, so the cooling step was not provided. The surface temperature on the cavity side of the first layer was measured using a surface thermometer after the pressure holding step of the primary molding was terminated and the molding was interrupted. In such molding, tanθ representing the amount of tilt and the amount of twist was maintained at about 0.000025 or less by the 4-axis parallel control mechanism.

The molding conditions of the secondary molding are the cylinder temperature of the second injection device 240 ° C., the hot runner set temperature 240 ° C., the injection rate 300 cm ³ / sec, the compression stroke 3.5 mm, the mold from the intermediate mold clamping state to the final mold clamping state The moving speed was 5 mm / second, and the pressure holding time was 130 seconds. Mold compression was started immediately before completion of filling, and the overlap was 0.5 seconds. Immediately after completion of filling, the valve gate was closed so that the molten resin did not flow backward from the gate to the cylinder. The pressure in the cavity (surface pressure) during compression was 10.0 MPa, and the pressure was maintained during the pressure holding time. The movable mold parting surface was not in contact with the fixed mold parting surface in the final advanced position. The cavity capacity in the intermediate clamping state under such molding conditions was 2.2 times the cavity capacity in the final clamping state.

The obtained two-layer molded product was taken out, allowed to stand for 24 hours under conditions of a temperature of 23 ° C. and a relative humidity of 50%, and sufficiently cooled, and then the evaluation results according to the evaluation items are shown in Table 1.
The “relative position” in the four-axis parallel control in Table 1 is “detected when the movable mold moves in parallel with the fixed mold by the four clamping mechanisms of the mold fixing plate. The average distance between the movable mold and the fixed mold is calculated from the detected value of the relative position between the movable plate and the fixed plate, and the detected value and average of each mold clamping mechanism are used as the command value to each mold clamping mechanism. A method of adding and subtracting the difference from the distance as a correction amount and maintaining the parallelism between the molds by feeding back and controlling the integrated value of the difference is shown.

[Example 2]
As the resin material for the second layer used for the secondary molding, the foamed PC resin pellets are used after drying at 120 ° C. for 5 hours, and the compression process is performed by four mold clamping mechanisms of the mold fixing plate. When moving parallel to the fixed mold, the mold clamping forces in the four clamping mechanisms are detected, the average value of the detected mold clamping forces is calculated, and the command values for each mold clamping mechanism are set in advance. A mold that maintains the parallelism between the molds by adding and subtracting the difference between the target mold clamping force of the mold clamping mechanism and the average value of the detected mold clamping force as a correction amount and feeding back the integrated value of the difference. A two-layer molded product was molded in the same manner as in Example 1 except that the tightening force method was used and the molding conditions were as shown in Table 1. The results of evaluating the obtained two-layer molded product are shown in Table 1.

[Example 3]
PC resin pellets are used as the first layer resin material for primary molding after drying at 120 ° C. for 5 hours, and PC / PET alloy resin is used as the second layer resin material for secondary molding at 110 ° C. The two-layer molded product was molded in the same manner as in Example 1 except that it was used after being dried for 5 hours, and the molding conditions were changed to those shown in Table 1. The results of evaluating the obtained two-layer molded product are shown in Table 1.

[Example 4]
After the second layer is molded, the movable mold is retracted again to form the third layer with a PC / PET alloy resin in accordance with the molding conditions of the first layer, except that the molding conditions are as shown in Table 1. All three-layer molded products were molded in the same manner as in Example 1. The results of evaluating the obtained three-layer molded product are shown in Table 1. Note that the surface temperature on the cavity side of the second layer measured after the pressure-holding step of the secondary molding under such molding conditions was 110 ° C.

[Example 5]
In order to maintain the parallelism between the molds by adjusting the parallelism between the fixed mold and the movable mold with the mold clamping mechanism at the four corners of the mold fixing plate, the compression process is performed at one corner. Example 1 except that the mold-clamping mechanism is the master and the master-slave method with the rest as the slave maintains the parallelism between the molds, and the molding conditions are as shown in Table 1. A two-layer molded product was molded. The results of evaluating the obtained two-layer molded product are shown in Table 1.
By making the compression process a master slave method, the warpage amount of the multilayer molded product was 162 μm / mm, which was larger than the warpage amount of the multilayer molded product obtained in Examples 1 to 4. Moreover, the interlayer adhesion of the multilayer molded product was slightly inferior to the adhesion of the multilayer molded product obtained in Examples 1 to 4. Note that the amount of warpage and adhesion are in a practically acceptable range.

[Comparative Example 1]
A two-layer molded product was molded in the same manner as in Example 1 except that the compression step was a method that did not control the parallelism between molds and the molding conditions were as shown in Table 1. The results of evaluating the obtained two-layer molded product are shown in Table 1.
Since the parallelism between the molds was not controlled in the compression process, the thickness of the multilayer molded product became non-uniform due to the influence of the unbalanced load generated by the pressure when filling the resin in the intermediate mold clamped state. In addition, as a result of local differences in the pressure applied to the multilayer molded product during molding, the amount of warpage of the multilayer molded product increased.

[Comparative Example 2]
A two-layer molded product was molded in the same manner as in Example 1 except that the injection compression molding was injection molding and the molding conditions were as shown in Table 1. The results of evaluating the obtained two-layer molded product are shown in Table 1.
“Short” in the evaluation results in Table 1 means that the molten resin was not completely filled up to the flow end side edge of the mold, so that a part of the multilayer molded product was missing and had an incomplete shape. Show.
In addition, each component of the symbol description above is as follows.
PC: Polycarbonate resin pellet (manufactured by Teijin Chemicals Ltd .: Panlite L-1225ZL100 (trade name))
PC / PET: PC / PET alloy resin pellets consisting of 10 parts by weight of wollastonite as inorganic filler, 60 parts by weight of polycarbonate resin, and 30 parts by weight of polyethylene terephthalate resin TPE: polyester thermoplastic elastomer resin pellets (Teijin Chemicals Ltd. ) Made by: Nouvelan Q4130AN (trade name))
Foamed PC: Polycarbonate resin pellets (manufactured by Teijin Chemicals Ltd .: Panlite L-1225ZL100 (trade name)) and 100 parts by weight of inorganic foaming agent (manufactured by Sankyo Kasei Co., Ltd .: Celmark MB9082 (trade name)) Foamed polycarbonate resin pellets blended with 2.5 parts by weight

It is a longitudinal cross-sectional view of the mold clamping apparatus which shows the state at the time of the start of a shaping | molding cycle. It is a longitudinal cross-sectional view of the mold clamping apparatus which shows the state before the start of injection molding or injection compression molding of the first layer by primary molding. It is a longitudinal cross-sectional view of the mold clamping apparatus which shows the state which is carrying out injection molding or injection compression molding of the 1st layer. It is a longitudinal cross-sectional view of the mold clamping apparatus which shows the state which opened the metal mold | die for secondary molding and is preparing for injection molding or injection compression molding. It is a longitudinal cross-sectional view of the mold clamping apparatus which shows the state which is carrying out injection molding or injection compression molding of the 2nd layer. It is a longitudinal cross-sectional view of the mold clamping apparatus which shows the state which has opened the mold and has taken out the 2 layer molded product. It is the front schematic diagram (7-A) and the side view (7-B) of the multilayer molded product created in the Example.

Explanation of symbols

10 mold clamping device 11 first injection device 12 second injection device 13 fixed mold 14 movable mold 15 mold device 16 mold clamping mechanism 18 mold opening / closing device 20 engagement device 21 fixed plate 22 movable plate 23 tie bar 24 position sensor 25 Guide 26 Support plate 27 Clamping chamber 28 Open chamber 31 First layer 32 of a two-layer molded product obtained by primary molding Second layer 33 of a two-layer molded product obtained by secondary molding 34 1st layer gate portion 35 2nd layer gate portion 36 A line (broken line) obtained by cutting a cross section to measure the thickness of each layer
37 Locations where the thickness of each layer was measured (16 locations in total)
38 Position of the resin filling portion of the primary molding (the trace of the resin filling portion generated by the primary molding is concealed by the second layer)
39 Trace of Resin Filled Part Generated by Secondary Molding 40 Flow Terminal Side Edge 41 Gate Side Edge 42 Test Piece Cutout (Shaded Line)

Claims (7)

A method for producing a multilayer molded article made of at least two layers of resin material, wherein a fixed mold and a movable mold are used, and the first layer is injection-molded by primary molding, and the movable mold is moved. A step of forming a cavity for secondary molding and a multilayer molded product in which the first layer and the second layer are fused by injection molding the second layer in a form laminated on the first layer by secondary molding. And at least one of the injection molding processes includes adjusting the parallelism between the fixed mold and the movable mold by a mold clamping mechanism at four corners of the mold fixing plate. injection compression molding der Risoshite the injection compression molding to maintain the parallelism between the movable mold moves to parallel with the fixed mold by (i) a mold clamping mechanism of the corners four positions of the mold fixing plate When the detected value of the relative position between the movable plate and the fixed plate is detected, the movable mold and the fixed die The average distance is calculated and the difference between the detected value of each mold clamping mechanism and the average distance is added to or subtracted from the command value to each mold clamping mechanism as a correction amount, and the integrated value of the difference is fed back and controlled. The injection compression molding that maintains the parallelism between the molds and / or (ii) when the movable mold moves parallel to the fixed mold by the mold clamping mechanism at the four corners of the mold fixing plate, The clamping force in the clamping mechanism at the four corners is detected, the average value of the detected clamping force is calculated, the target clamping force of the clamping mechanism set in advance to the command value to each clamping mechanism, and the above-mentioned It is injection compression molding that maintains the parallelism between the molds by adding and subtracting the difference from the average value of the detected clamping force as a correction amount and feeding back and controlling the integrated value of the difference.
A method for producing a multilayer molded article. The surface temperature of the cavity-side of the first layer when the glass transition temperature was Tg of the resin material used in the secondary molding [Tg-20] (℃) ~ [Tg + 50] (℃) a claimed in claim 1, For producing a multilayer molded article. In injection compression molding, the cavity capacity in the intermediate clamping state is in the range of 1.1 to 10.0 times the cavity capacity in the final clamping state, and the movable mold moves from the intermediate clamping state to the final clamping state. The method for producing a multilayer molded article according to claim 1 or 2 , wherein the compression speed is 5 mm / second or more for injection compression molding. The method for producing a multilayer molded article according to any one of claims 1 to 3 , wherein the thickness of each layer constituting the multilayer molded article is 1 mm to 50 mm. Thickness deviation divided by the thickness the thickness of the thinnest portion of each layer constituting the multilayer molded article (Ta) of the thickest portion (Tb) (Ta / Tb) is one of the claims 1-4 at least 0.7 A method for producing a multilayer molded article according to claim 1. The method for producing a multilayer molded article according to any one of claims 1 to 5 , wherein the amount of warping after the multilayer molded article is allowed to stand for 24 hours at 23 ° C and a relative humidity of 50% is 150 µm / mm or less. The method for producing a multilayer molded article according to any one of claims 1 to 6 , wherein the resin material is a thermoplastic resin.

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