JPS6369614A - Multi-layer reactive injection molding - Google Patents

Abstract

PURPOSE:To finish the curing of an outer layer and an inner layer at the same time shorten a molding time, by a method wherein catalyst for curing the molding materials for molding the outer layer and the inner layer of a molded form are contained in said materials at a specified ratio. CONSTITUTION:A first synthetic resin molding material 1 is injected into a cavity 6 under a condition that the amount of a catalyst, contained therein, is reduced so as to be capable of restricting the curing of the first synthetic resin molding material to a semi-cured state. Subsequently, a second synthetic resin molding material 2, containing the catalyst whose amount is sufficient for compensating the curing of the first synthetic resin molding material 1, is injected into the cavity 6. The first synthetic resin molding material 1 is not cured immediately after it is injected into the cavity 6 and is in flowable condition, therefore, the second synthetic resin molding material 2, injected subsequently, can flow smoothly without being precluded the flow of it. Further, the first and second synthetic resin molding materials 1, 2 finish the curing thereof at the same time by the catalyst, contained in the second synthetic resin molding material 2, therefore, a molding time may be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is directed to forming the inner layer of a molded article while injecting a resin molding material into a cavity of gold, which constitutes the outer layer of the molded article. The present invention relates to an improvement in a multilayer reaction injection molding method in which the second synthetic resin molding material is covered with the first synthetic resin molding material #1 by successively injecting the second synthetic resin molding material into the cavity.

(Prior art) In recent years, synthetic resin molding materials have been widely used in various industrial fields due to their excellent molding flexibility. Generally, these products have the disadvantage of low strength. and,
To overcome this drawback, it is common practice to increase the strength and rigidity of the synthetic resin molded product by mixing filler such as glass fiber into the synthetic resin molding material. However, when a filler is mixed in this way, the filler is exposed on the surface of the synthetic resin molded product, which is unfavorable in terms of appearance. Therefore, in order to improve the surface finishing accuracy of synthetic resin molded products, surface painting is performed on synthetic resin molded products, but the molding cycle time becomes longer and even if surface painting is applied, the filler will not affect the surface finish of synthetic resin molded products. This will cause the painted surface to become rough and require post-treatment.

In addition, when the synthetic resin molded product is made of polyurethane, for example, by injection foam molding, polyurethane has excellent moldability due to its good fluidity at low pressure, but it has poor weather resistance. As a result, the surface of the molded product will quickly discolor and deteriorate, so in order to prevent this, it is necessary to camouflage it by means such as painting as described above, and in this case as well, the molding cycle time will be longer. There is a problem.

Therefore, as a means to solve the above-mentioned problems, for example, as disclosed in JP-A-56-92038@, a first synthetic resin molding material is first injected into the cavity of the mold. While the center of the first synthetic resin molding material injected into the molding material remains in a fluid state without solidifying, the second synthetic resin molding material is injected into the second molding material.
By injecting a synthetic resin molding material into the first synthetic resin molding material, a multilayer injection molded product in which the second synthetic resin molding material is covered with the first synthetic resin molding material is produced (a method is known). .

(Problem to be solved by the invention) However, as mentioned above, the mold used for injection molding is generally set at the same mold temperature throughout the mold, and in this way, the mold temperature of the entire mold is When a multilayer synthetic resin molded product is injection molded using, for example, a reaction-curing synthetic resin molding material with a mold having the same settings, the following problems may occur.

In other words, when the mold temperature of the mold is set to the standard temperature for reaction injection molding, the multilayer synthetic resin molding is completed before the curing reaction of the first synthetic resin molding material constituting the outer layer of the multilayer synthetic resin molded product has progressed to some extent. The second layer that constitutes the inner layer of the resin molded product
Since the synthetic resin molding material is injected subsequent to the injection of the first synthetic resin molding material, there is a risk that the second synthetic resin molding material may be exposed on the outer (surface) layer of the first synthetic resin molding material. . In addition, if the mold temperature of the mold is set higher than the standard reaction injection molding temperature, the curing reaction rate of both the ``i'' and the second synthetic resin molding materials is too fast, so both synthetic resin molding The fluidity of the material within the cavity is inhibited, and the two synthetic resin molding materials cannot be filled into the cavity without any gaps, resulting in lack of thickness in the molded synthetic resin molded product or failure of the molding. There is a risk that surface defects such as dents may occur on the surface of the product. In general, when the reaction injection molding temperature at the mold temperature is set lower than the standard temperature, the curing reaction speed of both synthetic resin molding materials is too slow, so the two synthetic resin molding materials mix in the cavity. As a result, the frequency of exposure of the second synthetic resin molding material to the surface of the molded product increases, and there is a risk that the finish accuracy of the surface of the molded product may decrease.

The present invention has been made in view of the above, and its purpose is to mold a multilayer synthetic resin molded product using a reaction-curable synthetic resin molding material as described above. By adjusting the m of the catalyst that accelerates the curing reaction rate of the first and second synthetic resin molding materials, the curing reaction rate of the first synthetic resin molding material injected into the cavity is delayed and the first synthetic resin molding material is cured. is maintained in a semi-hardened state, thereby allowing the second synthetic resin molding material injected thereafter to smoothly flow into the first synthetic resin molding material. On the other hand, the delayed curing reaction rate of the first synthetic resin molding material is accelerated by the catalyst contained in or generated in the second synthetic resin molding material, so that the first and second synthetic resin molding materials are simultaneously cured. Make sure it completes. Therefore, the second synthetic resin molding material constituting the inner layer of the molded product is not exposed to the outer (surface) layer of the first synthetic resin molding material, and its fluidity is not inhibited, thereby reducing the layer thickness. In addition to ensuring that a multilayer synthetic resin molded product with uniformity and no surface defects is obtained, the molding cycle time is shortened without the need for additional surface coating. It is in.

(Means for Solving the Problem) In order to achieve the above object, the solution of the present invention is to inject the first synthetic resin molding material constituting the outer layer of the molded product into the cavity of the mold, and A multilayer reaction injection molding method in which the first synthetic resin molding material covers the second synthetic resin molding material by subsequently injecting the second synthetic resin molding material constituting the inner layer of the molding material into the cavity. In that case, first, the first synthetic resin molding material is heated in a state in which the amount of catalyst contained therein is reduced so that the first synthetic resin molding material can be suppressed to a semi-cured state. Inject into the cavity.Next, the first
Contains the above catalyst sufficient to compensate for the curing of the synthetic resin molding material, or reacts with the first synthetic resin molding material (thereby producing a catalyst sufficient to compensate for the curing of the first synthetic resin molding material). By injecting the second synthetic resin molding material containing a substance into the cavity, the second synthetic resin molding material is covered with the first synthetic resin molding material.33 (Operation) With the above configuration, in the present invention, the first synthetic resin molding material 1 constituting the outer layer of the molded product is placed within the four cavities of the mold.
The molding material 1 is ejected, and then the second synthetic resin molding material constituting the inner layer of the molded product is injected.

In this case, the fourth synthetic resin molding material contains the catalyst in a reduced amount to a level capable of suppressing the first synthetic resin molding material to a semi-hardened state. The second synthetic resin molding material contains the catalyst of W filter φ to supplement the curing of the first synthetic resin molding material, or the catalyst of W filter φ is added to the first synthetic resin molding material by reaction with the first synthetic resin molding material. (To compensate for σ!) Contains a substance that can produce the best catalyst. From this, it can be seen that the first synthetic resin molding material is not yet cured when it enters the caviar f. The molding material presses the first synthetic resin molding material without being hindered in its flow and smoothly flows inside the molding material toward the inner part of the cavity.

Also, the first synthetic resin molding material i! ■ is the inner side of the cavity (as the curing reaction progresses gradually, the curing reaction is also extended to the first synthetic resin molding material, and both cylinders 1
The curing of a3 and the first synthetic resin molding material is completed at the same time. Therefore, even if the flow of the second synthetic resin molding material acts on the first synthetic resin molding material, its exposure to the outer layer is inhibited. The multilayer synthetic resin molded product coated with the second synthetic resin molding material without surface defects can be reliably warped, and the molding cycle time can be shortened.

(Example) Embodiments of the present invention will be described below based on the drawings. .

FIG. 1 shows one culm molded in the multilayer reaction injection molding method according to the embodiment of the present invention. (This setting (the following two types of originals) will be used (temporarily referred to as A) and BR).

Δ liquid caprocutam 98.8 small h1 part catalyst (magnesium buc[1mide kabron cucum)
112-fold oral liquid turnip [1 lactam 60,000 parts! Rivolin (polynylene acyl lactam) 40 parts This 1a resin molded material 1'11 is prepared as follows: is able to suppress the first synthetic resin molding material 1 to a semi-hardened state.The outer part is being hardened due to the progress of the curing reaction, but the inner part is not yet hardened and is reduced to a fluid state. Incidentally, the appropriate amount for complete curing is as follows.

A liquid cabrolactam 7m 98 hand hanging catalyst (magnesium bromide caprolactam)
The second mold assembly section stores liquid A and liquid B of the first synthetic resin molding material 1 in respective storage tanks and a mixing head provided on one side of the mold 3 whose mold temperature is, for example, about 80 to 120°C. 4 without mixing, and during molding, both A and B are mixed in the mixing head 4 so that the mixing ratio is ff1ffi and A:B is 1:1. Immediately after mixing, as shown in FIG. 1(a), the mixed liquid, that is, the first synthetic resin molding material 1, was injected at a rate of 1009/sec into a cavity 6 with a capacity of 2.0 g through an injection port 5. Inject at a speed of 3 seconds.

On the other hand, following the indexing of the first synthetic resin molding material 1, it is injected into the cavity 6. The following two types of stock solutions (
Prepare liquids (temporarily referred to as liquid 8 and liquid B'). The liquid temperature of the above A' liquid is 35°C, and the liquid temperature of the B' liquid is 45°C.
Each temperature is set to ℃.

A' liquid carbodiimide modified medilene diisocyanate
100
Part A B' Liquid polyether polyol 100 parts Ethylene glycol 20 parts by weight Blowing agent (Freon-11) 2 parts Triethylene diamine
Type 1 oral part dibutyldendilaurate 0.0
1ffiff 1 part Sodium hydroxide 0.3
Part by weight Milled fiberglass 50 parts by weight ff 1 part This second synthetic resin molding material 2 supplements the hardening of the first synthetic resin molding material 1 by reacting with the first synthetic resin molding material 1 (caprolactam) in the above-mentioned mixing ratio. Liquid B contains a substance capable of producing a sufficient amount of catalyst, that is, sodium hydroxide as a catalyst.

Then, the liquid 8 and liquid B' of the second synthetic resin molding material 2 are poured between each storage tank and the mixing head 4 of the mold 3, as in the case of the first synthetic resin molding material 1. After the first synthetic resin molding material 1 is circulated without being mixed, and approximately 10 seconds have elapsed after the completion of injection of the first synthetic resin molding material 1,
The above-mentioned A-liquid and B-liquid are mixed in the mixing head 4 so that the mixing ratio becomes A liquid: B liquid = 1:1.55 in the mold part ratio, and then, as shown in Fig. 1 (b ), as shown in
Immediately, this mixed liquid, that is, the second synthetic resin molding material 2, was introduced into the cavity 6 through the injection port 5 at a rate of 1000 g/SeC.
Inject for 2.1 seconds at an injection speed of . This allows the first
As shown in Figure (C), the second synthetic resin molding material 2 is
The inside of the cavity 6 is filled with the first and second synthetic resin molding materials 1 and 2 while being press-fitted into the synthetic resin molding material 1 .

Thereafter, the first and second synthetic resin molding materials 1.2 are left in the cavity 6 for about 6 Qsec, and the first and second synthetic resin molding materials 1.2 are heated to the mold temperature of the mold 3. By curing 2, the layer thickness is about 100~20
A multilayer synthetic resin molded product having a layer thickness of 2 m was obtained, in which an inner layer made of foamed polyurethane was covered with an outer layer made of 0 μm nylon.

Next, the behavior of the first and second synthetic resin molding materials 1 and 2 in the cavity 6 during this period will be explained with reference to FIG. In FIG. 2, the broken line C represents the degree of reaction hardening of the first synthetic resin molding material 1, and the solid line C represents the degree of reaction hardening of the second synthetic resin molding material 2.

First, as shown in FIG. 1(a), even after approximately 10 seconds have elapsed since the first synthetic resin molding material 1 was injected into the cavity 6, the catalyst (magnesium bromide caprolactam) in the liquid A still remains. The curing reaction of the first synthetic resin molding material 1 is stopped midway and the portion in contact with the cavity 6 is cured, but the other parts of the first synthetic resin molding material 1 are hardened. The portion has not yet hardened and is in a fluid state, so-called a semi-hardened state.

Next, as shown in FIG. 1(b), when the second synthetic resin molding material 2 is injected into the cavity 6 after approximately 1 Qsec has elapsed since the first synthetic resin molding material 1 was injected, at this time, The injection pressure causes the second synthetic resin molding material 2 to penetrate into the first synthetic resin molding material 1 which is in a semi-cured state.
Push it towards the back of cavity 6 and press the
), both the first and second synthetic resin molding materials 1
, 2 to fill the inside of the cavity 6.

During this time, the sodium hydroxide in the second synthetic resin molding material 2 reacts with the caprolactam that has not yet reacted with the catalyst (magnesium bromide caprolactam) in J3 of the first synthetic resin molding material 1. An anionic catalyst (sl=lium cabrolactam) as shown below is produced.

The anionic catalyst (sodium cafluoractam) produced by this reaction reacts with the 1 ribolimer (polyether acyllactam) as a reaction initiator (polymerization catalyst) in the first synthetic resin molding material 1, thereby allowing the first synthetic resin to be synthesized. The curing reaction that was suppressed due to the lack of the catalyst (magnesium bromide caprolactam) in the resin molding material 1 is promoted, and the first synthetic resin molding material 1'11 can be completely cured by reaction. Comparing the physical properties of the multilayer synthetic resin molded product molded in this manner with that of a conventional single polyurethane molded product, as shown in Table 1, the product of this example is better than the conventional example in terms of heat resistance, impact resistance J3, and surface finish. Turns out it's better than anything else. In addition, in Table 1, the test item () refers to heat sag according to the JIS standard (ASTM-D3769 method), and overhang ff1 (100 s (length)
120 samples of x25sg (width) x3m<thickness)
The amount of drooping of the tip when heated in an oven at ℃ for 1 hour is shown, and this is used as a measure of heat resistance. In addition, the PGD value refers to a value measured using a skin luster sharpness measuring device (manufactured by Kusuga Test Disposal Co., Ltd.).

Table 1 As described above, in this example, the catalyst (magnesium bromide lactam) contained in the first synthetic resin molding material 1 was able to suppress the first synthetic resin molding material 1 to a semi-cured state. On the other hand, the second synthetic resin molding material 2 can contain sufficient amount of caprolactam to compensate for the hardening of the first synthetic resin molding material 1. Contains thorium hydroxide.For this reason, the first synthetic resin molding material 1 contains 21v
The second synthetic resin molded material 1'l2, which is injected directly into the plastic molding 6, is still in a fluid state without being hardened, and the second synthetic resin molded material 1'l2, which is subsequently injected after the first injection, is in a fluid state without being hindered in its flow. The resin molding material 1 can smoothly flow toward the inner part of the cavity G. Moreover, the second synthetic resin molding material 2
The curing reaction gradually regresses toward the inner part of the cavity 6, and the hydroxide contained therein reacts with the caprolactam in the first synthetic resin molding material 1, resulting in the formation of J. The effect of the catalyst (helium caplactam) on the prepolymer (polyneedleacyllactam) promotes the curing reaction of the first synthetic resin molding material 1, thereby forming both the first and first synthetic resin moldings. Timber paddy 1
, 2 are completed simultaneously.

Therefore, the flow pressure of the second synthetic resin molding material 2 acts on the first synthetic resin molding material 1 to prevent the ()-i: from being exposed to the outer layer. It is possible to reliably produce a multilayer synthetic resin molded product coated with the second synthetic resin molding material 2 without surface defects, and it is also possible to shorten the molding cycle time without the need for a separate surface coating. can.

Furthermore, in the above embodiment, since the first synthetic resin molding material 1 injected into the cavity 6 is nylon, its curing reaction is an endothermic reaction, and it is thought that the mold temperature decreases during the molding process. .

However, after that, the second
Since the synthetic resin molding material 2 is polyurethane, its curing reaction is an exothermic reaction, and the mold temperature that decreases due to the endothermic reaction can be compensated for by this exothermic reaction. There is an advantage that synthetic resin molding materials 1 and 2 having different properties can be simultaneously injection molded.

In addition, in the above embodiment, the second synthetic resin molding material 2 is used as a means for accelerating the curing reaction of the first synthetic resin molding material 1.
It contains sodium hydroxide, but is not limited to this.
For example, potassium hydroxide reacts with caprolactam in the first synthetic resin molding material 1 to form a catalyst (lactam anion).
Any alkali metal hydroxide or the like that is capable of producing .

Further, in the above embodiment, the curing reaction rate of the first synthetic resin molded stone 1 is promoted by reacting the sodium hydroxide in the second synthetic resin molded product 2 with the caprolactam in the first synthetic resin molded product 1. However, the present invention is not limited to this, for example, the first synthetic resin molded material described above! By blending the same catalyst (magnesium bromide caprolactam) used in f41 into the second synthetic resin molding material 2 to compensate for the deficiency, the prepolymer (polyether acyllactam) in the first synthetic resin molding material 1 can be obtained. It is also possible to completely cure the first synthetic resin molding material 1 by reacting with the resin.

Furthermore, in the above example, the content of WC (magnesium bromide caprolactam) in the first synthetic resin molding material 1 was reduced to a base that can suppress the hardening state of the first synthetic resin molding material 1 to a semi-hardened state. Not limited to, for example, the above mentioned! (
To maintain the first synthetic resin molding material 1 in a semi-cured state by reducing the amount of prepolymer (polyether acyllactam) as a reaction initiator (polymerization catalyst) that reacts with magnesium bromide caprolactam). It is also possible.

(Effects of the Invention) As explained above, according to the present invention, while the first synthetic resin molding material constituting the outer layer of the molded product is injected into the cavity of the mold, the second synthetic resin molding material constituting the inner layer of the molded product is injected into the mold cavity. When the resin molding material is subsequently injected into the cavity, the amount of catalyst in the first synthetic resin molding material is reduced. On the other hand, as a result of this, the first layer was not completely cured but was in a semi-cured state.
The above-mentioned second synthetic resin molding material contains an amount of the catalyst sufficient to compensate for the curing of the synthetic resin molding material, or a substance capable of producing an amount of catalyst sufficient to compensate for the curing of the first synthetic resin molding material by reaction with the first synthetic resin molding material. It is mixed into a synthetic resin molding material. Therefore, immediately after being injected into the cavity, the first synthetic resin molding material is not yet cured and is in a fluid state, and the second synthetic resin molding material that is subsequently injected is in a fluid state without being hindered in its flow. 1. The synthetic resin molding material can flow smoothly inside the cavity toward the eastern side. Moreover, the curing reaction of the second synthetic resin molding material progresses gradually as it goes toward the inner part of the cavity, and the curing reaction also extends to the first synthetic resin molding material, thereby curing both cylinders 1 and the second synthetic resin molding material. is completed at the same time, so that even if the flow pressure of the second synthetic resin molding material acts on the first synthetic resin molding material, it is prevented from being exposed to the surface layer. Therefore, it is possible to reliably produce a multilayer synthetic resin molded product with no surface defects by covering the second synthetic resin molding material with the first synthetic resin molding material, and to shorten the molding cycle time.

[Brief explanation of the drawing]

Fig. 1 is a process diagram showing the molding procedure of a multilayer reaction injection molding method according to an embodiment of the present invention, and Fig. 2 is data showing the reaction hardening degree of the first and second synthetic resin molding rates in the cavity. . DESCRIPTION OF SYMBOLS 1... First synthetic resin molding material, 2... Second synthetic resin molding material, 3... Mold, 6... Cavity. Patent applicant Mazda Motor Corporation representative
In front of people 1) Hiroze, ;, '2nd figure inclination: ikoS,...: Figure 1 (b

Claims (1)

[Claims] (1) By injecting a first synthetic resin molding material constituting the outer layer of the molded product into the cavity of the mold, and subsequently injecting a second synthetic resin molding material constituting the inner layer of the molded product into the cavity, A multilayer reaction injection molding method in which a second synthetic resin molding material is coated with the first synthetic resin molding material, wherein the amount of the catalyst contained in the first synthetic resin molding material is the same as that of the first synthetic resin molding material. The material is injected into the cavity in a reduced amount that can be suppressed to a semi-cured state, and then the catalyst is contained in an amount sufficient to compensate for the curing of the first synthetic resin molding material, or the first synthetic resin molding material is By injecting into the cavity the second synthetic resin molding material containing a substance capable of producing an amount of catalyst sufficient to compensate for the curing of the first synthetic resin molding material by reaction with the synthetic resin molding material, A multilayer reaction injection molding method characterized in that a first synthetic resin molding material coats a second synthetic resin molding material.