JPH11129280A - Reaction injection molding method and reaction stock solution for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reaction injection molding method suitable for the production of a molded article which can prevent or greatly reduce the generation of voids and bubbles. SOLUTION: A reaction base liquid is added with 0.001-3 wt.%, preferably 0.01-2 wt.%, especially 0.02-1 wt.%, based on the total weight of the stock solution, of polymer particles 0.08-0.5 mm, preferably 0.1-0.3 mm in particle size which are insoluble in the stock solution to be used for bulk polymerization in a mold. The mold has a cavity 6 which divides the form of a molded article, an injection port for the injection of the stock solution into the cavity 6, a liquid storage part 4 formed to communicate with the uppermost position of the cavity 6 and a narrow passage 5 which connects the cavity 6 with the liquid storage part 4. When the reaction stock solution passes through the passage 5, the viscosity of the liquid increases to enable the application of holding pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a reaction injection molding method preferably using a norbornene-based monomer and a reaction stock solution used for the method. More specifically, during the bulk polymerization by injecting the undiluted reaction solution into the mold, by adding specific particles in a specific amount, the holding pressure in the mold is performed without a special mechanism, and the generation of voids and bubbles The present invention relates to a reaction injection molding method and an undiluted reaction solution capable of obtaining a molded article in which a molded product is prevented or significantly reduced.

[0002]

2. Description of the Related Art A method of using a holding pressure in a mold to remove gas in a mold Molding is performed by performing a bulk polymerization reaction (curing) in a mold using a reaction stock solution containing a norbornene-based monomer and a metathesis catalyst system. In the reaction injection molding method for producing a body, generally,
Reaction stock solution containing monomer and metathesis catalyst system (Solution B)
And a reaction solution (solution A) containing a monomer and an activator are mixed in a mixing section such as a mixing head, and then the mixed solution is injected into a mold and reacted. Bubbles (gas) mixed in the mixing chamber and gas in the mold are discharged to the outside through an air vent provided at a position where the gas of the mold is stored last at the time of injecting the reaction stock solution.

However, when a molded article is manufactured by a reaction injection molding method using a reaction stock solution containing a norbornene-based monomer, a large number of voids (bubbles and voids) are generated inside and on the molded article. In particular, this is remarkable in a thick molded product or a molded product having a deformed portion. This is due to the incorporation of bubbles of the reaction solution and incomplete filling of closed portions such as bosses and ribs.

As a means for solving this problem, a method for keeping the pressure in a mold is well known in all injection molding methods including reaction injection molding. As an example of using the method of holding pressure in a mold in reaction injection molding, a reaction stock solution containing a norbornene-based monomer and a metathesis catalyst system was injected into a mold at a temperature higher than the mold temperature and injected into the mold. Thereafter, a method of maintaining the pressure in the mold (Japanese Patent Application Laid-Open No. 239915/1990), a method in which a stock solution containing a norbornene-based monomer and a metathesis catalyst system is injected into the mold to perform bulk polymerization, and the pressure in the mold is maintained at a certain level. A method of providing a pressure holding mechanism in an air vent of a mold to hold the pressure (Japanese Patent Laid-Open No. 4-348122) has been proposed.

In the method described in Japanese Patent Application Laid-Open No. 2-239915, since the pressure of the reaction solution is maintained by the pressurizing device after the reaction solution is injected into the mold, the timing of pressurization is precisely controlled, and the timing is adjusted immediately before the reaction solution is hardened. Unless the pressure is maintained, a good molded product cannot be obtained. However, in a reaction solution containing a norbornene-based monomer and a metathesis catalyst system, the bulk polymerization reaction generally proceeds in a very short time, and the timing of pressurization is determined even when a large number of pressure and temperature sensors are used. It is difficult to use such a sensor, and the use of the sensor is accompanied by restrictions on mold processing, which increases the cost.

The method described in Japanese Patent Application Laid-Open No. 4-348122 requires a special device such as a pressure-holding mechanism using a pressurized gas for an air vent. In addition, during the period from the mold clamping to the holding pressure through the injection of the undiluted reaction solution, it is necessary to prevent the gas from leaking from other than the air vent provided with the holding pressure mechanism even if the mold is deformed. For this reason, a precise and extremely rigid mold is generally required, and the available mold is limited.

[0007] A filter is used for removing gas in a mold.
Methods As a method for obtaining a good reaction injection molded article, a method for preventing entrapment of bubbles is also known. Specifically, a method is known in which only a gas is allowed to pass through a filter and not a reaction stock solution. Examples of the method using a filter include a gas outlet having a filter when a metathesis polymerization monomer is poured into a molding mold in the presence of a metathesis polymerization catalyst system to obtain a crosslinked polymer molded product by a reaction injection molding method. (Japanese Patent Laid-Open No. 1-163033).

In the method described in Japanese Patent Application Laid-Open No. 1-163033, it is necessary to provide a filter in all the closed portions, so that not only the structure of the mold becomes complicated, but also the strength required for realizing the complicated structure. There is a limitation on the mold material to secure. Furthermore, a filter having a size of 0.02 mm or more and 0.1 mm or less is used as a filter that allows gas to pass therethrough and does not allow liquid to pass therethrough. In addition to the occurrence of clogging, even when there is no clogging, the time required for injecting the undiluted reaction solution increases due to the high passage resistance at the time of outflow of the gas in the mold, thereby restricting the reaction start time in the mixed solution.

[0009] A method of adding an insoluble filler to a blended liquid [0010] An insoluble filler is used in a reaction stock solution containing a norbornene-based monomer and a metathesis catalyst system, and an epoxy-based or urethane-based reaction stock solution used in other reaction molding methods. Is generally known. Since the purpose of the addition in these conventional methods is to improve the material mechanical properties of the molded product, it is common knowledge that at least 5% by weight or more based on the total amount of the reaction stock solution is added. As an example of a conventional method, a method of adding polyethylene to polycycloolefin to improve impact resistance (Japanese Patent Laid-Open No. 59-8131)
No. 5).

In JP-A-59-81315, at least 5% by weight or more based on a monomer, preferably 10 to 20% by weight.
It is stated that the polyethylene particles are required to improve the impact resistance by weight%, and the conventional mechanically added amount changes the material mechanical properties of the molded product as in this example.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reaction injection molding method suitable for producing a molded article in which the generation of voids and bubbles can be prevented or greatly reduced. is there.

[0012]

Means for Solving the Problems The present inventors have conducted intensive studies to overcome the problems of the background art, and as a result, by adding a small amount of insoluble particles to a reaction stock solution,
(1) Since the addition amount of the particles is significantly smaller than the addition amount required to change the material mechanical properties of the molded body, the properties of the molded body due to the reaction stock solution are not changed.
(2) When the bulk polymerization reaction starts to proceed rapidly after the reaction stock solution starts flowing out of the cavity to the liquid reservoir provided with the air vent section, the viscosity rise is slight immediately after the bulk polymerization reaction starts to proceed. As a result, the fluidity hardly changes as a whole.However, the apparent viscosity of the undiluted reaction solution suddenly rises due to the effect of the added particles in the part flowing out to the liquid reservoir, which is narrower than the product part. With the fluidity assured, the apparent viscosity only at the outlet increases, and the pressure inside the mold is automatically maintained. (3) Leakage that flows out of the mold to other than the liquid reservoir Even if the mold is leaking, the internal pressure inside the mold becomes higher than a certain level as well as outflow to the liquid reservoir at the location where the leak occurs. The pressure in the mold at or above a certain level at the time of and after the injection is stopped Being held, as a result, when producing a thin molded body, a thick molded body, or an uneven thickness molded body, generation of voids inside or on the surface of the molded body and filling in closed portions such as bosses and ribs It has been found that the occurrence of chipping due to shortage is extremely small, the molded article is not deformed, and a molded article excellent in both appearance and physical properties can be obtained.

The finding that the apparent viscosity of the undiluted reaction solution at the outflow portion increases with almost no change in the overall fluidity before the start of the reaction was found by the present inventors for the first time. Has been completed based on these findings.

Thus, the reaction injection molding method according to the first aspect of the present invention is characterized in that polymer particles having a particle size of 0.08 mm or more and 0.6 mm or less, preferably 0.1 mm or more and 0.3 mm or less and insoluble in a reaction stock solution. Is added in an amount of 0.001 to 3% by weight, preferably 0.01 to 2% by weight, and particularly preferably 0.02 to 1% by weight, based on the total amount of the reaction stock solution. Is characterized by bulk polymerization.

The undiluted reaction solution according to the present invention contains polymer particles having a particle size of 0.08 mm or more and 0.6 mm or less and insoluble in the undiluted reaction solution in an amount of 0.000 mm to the total amount of the undiluted reaction solution.
It is characterized in that 1 to 3% by weight is added.

If the particle diameter in the above range is preferable, if it is too small, the effect of increasing the dwell pressure is small, and if it is too large, blockage by particles in a narrow portion of the flow path such as the outflow portion is not preferable. Because. Also, as the amount of particles added, the above range is preferable, if the amount of addition is too small,
This is because if the effect of increasing the holding pressure is small and too large, the material mechanical properties of the molded body change and the mold clamping pressure increases, which is not preferable.

In the present invention, preferably used molds are formed so as to communicate with a cavity for defining the shape of the molded body, an inlet for injecting the undiluted reaction solution into the cavity, and the uppermost position of the cavity. And a narrow passage connecting the cavity and the liquid reservoir.
In the present invention, when the reaction solution passes through this narrow passage,
This is because the viscosity of the undiluted reaction solution increases, and it becomes possible to apply pressure. From such a viewpoint, the gap of the passage is
Preferably 0.8-3.0 mm, more preferably 1.
0 to 1.5 mm. If the gap is too small, it is not preferable because the flow of the reaction solution to the liquid reservoir becomes difficult, and if the gap is too large, the increase in the viscosity of the reaction solution is small.

In a reaction injection molding method according to a second aspect of the present invention, a cavity defining a shape of a molded article, an inlet serving as an inlet for injecting a reaction solution into the cavity, and an uppermost position of the cavity are communicated. A mold having a liquid reservoir formed by the above method and a narrow passage connecting the cavity and the liquid reservoir is prepared, and has a particle diameter of 0.08 mm or more and 0.6 mm or less, and is insoluble in the reaction solution. The particles are added to the reaction stock solution,
The undiluted reaction solution is filled from the injection port of the mold into the cavity until the undiluted reaction solution flows into the liquid reservoir through the passage.

Particles Insoluble in Undiluted Solution In the present invention, the polymer particles insoluble in undiluted reaction solution preferably have a shape close to spherical. If the shape of the particles is an elongated shape such as a rod, even if the cross section of the flow path is larger than the cross section of the particle, the flow path may block the flow path, and the shape of the mold is limited, which is not practical. Therefore,
As for the particle shape to be used, the aspect ratio is desirably in the range of 1.5 or less and closer to a spherical shape.

The insolubility in the reaction stock solution is determined as long as the dispersion of the particles in the reaction stock solution is completed at least immediately before molding. It may not necessarily be insoluble in a strict sense as long as it is insoluble in such a degree that it is kept below, for example, particles that are hardly dissolved at 35 ° C. or lower which is the upper limit of the temperature of a normal reaction stock solution storage container Should be fine. In other words, the term “insoluble” in the present invention is not used in a strict sense, and it is difficult to dissolve such that the particle diameter of the particles is maintained at 0.08 mm or more and 0.6 mm or less in the reaction stock solution storage container. It also includes things that have potential.

In the present invention, insoluble polymer particles are used. Examples of the polymer particles include polyethylene, polystyrene, phenol resin, epoxy resin, acrylic resin, and vinyl chloride resin. Of these, particles made of polyethylene are particularly preferred.

Since the amount of the particles used in the present invention is small relative to the total amount, the particles may inhibit the bulk polymerization of the reaction solution. However, when it is desired to terminate the polymerization reaction in a very short time. When it is necessary to make the polymerization degree of the molded product obtained by bulk polymerization or a very high level, it is desirable that the polymerization does not inhibit the bulk polymerization, and from such a viewpoint,
For example, polyethylene particles are used. Furthermore, the amount of particles that can be added in the present invention is such that the material mechanical properties of the molded body do not change with the addition of the particles, but is so small that visual observation in the molded body is impossible by the addition of the particles. In order to avoid the existence of a minute amount of voids and, for example, to prevent fluctuations before and after the addition of electrically insulating particles, it is desirable that the particles be swollen and fused by the norbornene-based monomer during bulk polymerization. From such a viewpoint, for example, particles made of medium density and low density polyethylene are preferably used.

The present invention is not limited to the method using two kinds of undiluted reaction solutions. For example, various modifications are possible, such as putting a monomer and a desired additive in a third container and using it as a third reaction stock solution. Also in this case, the proportion of the insoluble particles in the total amount of the reaction stock solution is 0.01% by weight or more.
If it is not more than weight%, it may be dispersed in any of the three kinds of reaction stock solutions or may be dispersed in all the reaction stock solutions. In addition,
The reaction stock solution is usually stored and operated under an atmosphere of an inert gas such as nitrogen gas.

Reaction Injection Molding In the present invention, the reaction solution used for reaction injection molding is not particularly limited, but may be urethane, urea, nylon, epoxy, unsaturated polyester, phenol, norbornene or the like. And a norbornene-based compound is particularly preferable. As a general molding condition, before injection into a mold, the reaction stock solution temperature is 20 to 80 °.
C, the viscosity of the reaction stock solution is, for example, at 30 ° C.
5 cps to 3000 cps, preferably 100 cps to 1
It is about 000 cps.

In such molding, a reinforced polymer (molded body) can be manufactured by placing a reinforcing material in a mold in advance and supplying a reaction liquid therein to polymerize. As the reinforcing material, for example, glass fiber, aramid fiber, carbon fiber, ultra high molecular weight polyethylene fiber,
Examples include metal fibers, polypropylene fibers, aluminum-coated glass fibers, cotton, acrylic fibers, boron fibers, silicon carbide fibers, and alumina fibers. These reinforcing materials can be used in various shapes, such as those obtained by forming a long fiber or chopped strand into a mat, woven into a cloth, or remaining in a chopped shape. It is preferable that the surface of these reinforcing materials is treated with a coupling agent such as a silane coupling material in order to improve the adhesion to the resin. The amount to be used is not particularly limited, but is usually 10% by weight or more, preferably 20 to 60% by weight of the total weight of the molded article.

Further, various additives such as an antioxidant, a filler, a pigment, a colorant, a foaming agent, a flame retardant, a sliding imparting agent, an elastomer, a dicyclopentadiene-based thermopolymerized resin and a hydrogenated product thereof are blended. Thereby, the properties of the obtained polymer can be modified.

As the antioxidant, there are various antioxidants for plastics / rubbers such as phenol type, phosphorus type and amine type. Fillers include inorganic fillers such as milled glass, carbon black, talc, calcium carbonate, aluminum hydroxide, mica, potassium titanate, calcium sulfate, and the like. Examples of the elastomer include natural rubber, polybutadiene, polyisoprene, styrene-butadiene copolymer (SBR), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), and ethylene- Examples include propylene-diene terpolymer (EPDM), ethylene vinyl acetate copolymer (EVA) and hydrides thereof.

The additive is usually mixed in advance with one or both of the reaction stock solutions. In the present invention, the additive has a particle size of 0.08 mm or more and 0.6 mm or more.
Hereinafter, when the particles are insoluble in the reaction stock solution, the additive is used in an amount of 0.00% with respect to the total amount of the reaction stock solution.
Preferably, it is added in an amount of 1 to 3% by weight.

The polymerization time may be appropriately selected, but is usually about 20 seconds to 20 minutes after the completion of the injection of the reaction solution.

In the present invention, the temperature of the mold during the reaction injection molding is usually at least room temperature, preferably 10 to 200 ° C.
More preferably, the temperature is controlled at 20 to 130 ° C, and still more preferably at 30 to 100 ° C. In addition, before injecting the undiluted reaction solution into the mold, circulate warm air inside the mold,
After at least the inside of the cavity of the mold is heated to a predetermined temperature, the flow of the warm air may be stopped, and the reaction stock solution may be poured into the cavity of the mold apparatus to perform the reaction injection molding. In particular, it is preferable that after the insert member integrated with the reaction injection molded body is arranged inside the cavity of the mold apparatus, warm air is circulated inside the cavity of the mold apparatus.
After arranging a reinforcing material integrated with the reaction injection molded body inside the cavity of the mold, it is also preferable to flow warm air into the cavity of the mold apparatus. By preheating these insert members or reinforcing materials, the adhesion between them and the molded body is improved.

The material of the mold used in the present invention is as follows.
There is no particular limitation, and the material is not limited to metals such as cast iron, iron, stainless steel, aluminum and nickel electroformed, and may be a synthetic resin or other materials. Reaction injection molding can be performed at a relatively low pressure, and it is not always necessary to use a highly rigid mold.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 is a sectional view of a main part of a mold used in a reaction injection molding method according to one embodiment of the present invention.

In the present embodiment, a stock solution containing a norbornene monomer and a metathesis catalyst system is used.

[0035] As the norbornene-based monomer used in the norbornene-based monomer present embodiment may be either as long as it has a norbornene ring, the use of polycyclic norbornene monomer having three or more rings body, high thermal deformation temperature Weight Coalescence is obtained. Further, in order to make the ring-opened polymer to be thermoset, at least 10% by weight, preferably 30% by weight or more of all the monomers may be used as a crosslinkable monomer.

Specific examples of norbornene-based monomers include bicyclics such as norbornene and norbornadiene; tricyclics such as dicyclopentadiene (cyclopentadiene dimer) and dihydrodicyclopentadiene; and tetracyclics such as tetracyclododecene. Pentacyclic ring such as cyclopentadiene trimer; heptacyclic ring such as cyclopentadiene tetramer; alkyl-substituted (eg, methyl, ethyl, propyl, butyl-substituted) and alkenyl-substituted (for example) Vinyl-substituted), alkylidene-substituted (eg, ethylidene-substituted), aryl-substituted (eg, phenyl,
And a substituent having a polar group such as an ester group, an ether group, a cyano group, or a halogen atom. These monomers may be used in combination of one or more kinds. Among them, tricyclic, tetracyclic, or pentacyclic monomers are preferable from the viewpoint of easy availability, excellent reactivity, and excellent heat resistance of the obtained resin molded product.

The crosslinking monomer has two reactive double bonds.
It is a polycyclic norbornene-based monomer having at least one monomer, and specific examples thereof include a cyclopentadiene trimer. When the norbornene-based monomer and the crosslinkable monomer are the same, it is not necessary to use any other crosslinkable monomer.

It should be noted that, within a range not to impair the object of the present invention,
Monocyclic cycloolefins such as cyclobutene, cyclopentene, cyclopentadiene, cyclooctene and cyclododecene, which can be ring-opening copolymerized with norbornene monomers,
It may be used as a comonomer.

Metathesis Catalyst System In the present invention, a known metathesis catalyst system comprising a metathesis catalyst and an activator can be used as a catalyst for ring-opening polymerization of norbornene monomers.

The metathesis catalyst is tungsten hexachloride,
There is no particular limitation as long as it is a known metathesis catalyst as a bulk polymerization catalyst for norbornene-based monomers such as organic ammonium molybdate such as tridodecyl ammonium molybdate or tri (tridecyl) ammonium molybdate. Salts are preferred.

As the activator (cocatalyst), JP-A-58-1983
127728, JP-A-4-226124,
JP-A-58-129003, JP-A-4-1452
There is no particular limitation as long as it is a known activator as disclosed in Japanese Patent No. 47, for example, alkyl aluminum halides such as ethyl aluminum dichloride and diethyl aluminum chloride, organic aluminum compounds such as alkoxyalkyl aluminum halides, and organic tin. And the like.

The metathesis catalyst is usually used in an amount of about 0.01 to 50 mmol per 1 mol of the norbornene monomer,
Preferably, it is used in the range of 0.1 to 20 mmol.
The activator is preferably incorporated into the metathesis catalyst component, preferably
It is used in the range of 10 to 10 (molar ratio). It is preferable that both the metathesis catalyst and the activator are dissolved in a monomer before use. However, the metathesis catalyst and the activator may be suspended or dissolved in a small amount of a solvent as long as the properties of the product are not substantially impaired.

Other optional components The norbornene-based polymer may contain additives such as an antioxidant, a filler, a reinforcing agent, a pigment, a colorant, and an elastomer. These additives are dissolved or dispersed in the reaction stock solution and then compounded, but may be provided in a mold in some cases.

Examples of the elastomer added to the reaction stock solution include natural rubber, polybutadiene, polyisoprene, styrene-butadiene copolymer (SBR), and styrene-butadiene-styrene block copolymer (SB).
S), styrene-isopropene-styrene copolymer (S
IS), ethylene-propylene-dienter polymer (EPDM), ethylene-vinyl acetate copolymer (EV
A) and hydrides thereof. When these elastomers are added to the reaction solution, not only the resulting polymer is given impact resistance, but also the viscosity of the reaction solution can be adjusted.

[0045] In the reaction injection mold this embodiment, the inlet, using a cavity, and reaction injection mold having a reservoir with an air vent. The mold of the present embodiment usually has a split mold structure, and as shown in FIG.
When the mold is completely closed, a space (cavity 6) for forming a molded body is formed.

As will be described later, an unreacted solution (solution B) containing a monomer and a metathesis catalyst and an unreacted solution (solution A) containing a monomer and an activator are mixed in a mixing section such as a mixing head. The undiluted solution) is injected into a mold and reacted. After the reaction, it is injected into the cavity from the injection port whose cross-sectional area is narrowed down, and fills the cavity while expelling the gas inside.

When mixing the liquid A and the liquid B, many bubbles (gas) are likely to be entrained.
Is provided with a liquid reservoir 4, and a reaction stock solution at the initial stage of mixing is removed through a narrow passage 5 extending from a cavity 6 provided at a joint between the two molds to the liquid reservoir 4. The liquid reservoir 4 is used for
The reaction solution in the cavity 6 is difficult to be filled, and is installed at a position where gas is stored last (at the top). The shape and size of the liquid reservoir 4 can be appropriately determined depending on the size and shape of the molded body. In FIG. 1, reference numeral 3 denotes a seal groove, in which a sealing material is inserted to seal between the split surfaces of the molds 1 and 2.
The gap of the passage 5 is preferably 0.8 to 3.0 mm.
It is.

In a preferred method of producing the bulk polymerized norbornene-based polymer, the norbornene-based monomer is generally divided into two parts and placed in separate containers, one of which is added with a metathesis catalyst, and the other is added with an activator. Prepare a stable reaction stock solution. The two kinds of reaction stock solutions are mixed, and then injected into a mold having a predetermined shape, where ring-opening polymerization is performed in bulk. In the present embodiment, a collision mixing device conventionally known as a reaction injection (RIM) molding device can be used to mix two types of reaction stock solutions. In this case, the containers containing the two types of undiluted reaction solutions serve as separate flow sources. The two streams are instantaneously mixed with the mixing head of the RIM machine and then injected into a molding die where they are immediately bulk polymerized to obtain a molded body.

In addition to the collision mixing device, a low-pressure injector such as a dynamic mixer or a static mixer can be used. In the case where the pot life at room temperature is as long as one hour, after the mixing of the two reaction solutions in the mixer is completed, the mixture may be injected or poured several times into a preheated mold, , May be injected continuously. In the case of this method, the size of the apparatus can be reduced as compared with the collision mixing apparatus, and the apparatus can be operated at a low pressure.

In the present embodiment, when the unreacted solution containing the norbornene-based monomer and the metathesis catalyst system is injected into a mold to perform bulk polymerization, the particle size is from 0.08 mm to 0.6 m.
m or less, desirably 0.1 mm or more and 0.3 mm or less, insoluble particles in the reaction solution containing the norbornene-based monomer and the metathesis catalyst system in an amount of 0.001 to 3 with respect to the total amount.
% By weight, preferably 0.01% by weight or more and 2% by weight or less, particularly preferably 0.02% by weight or more and 1% by weight or less. The insoluble particles may be dispersed only in one of the two types of reaction stock or in both as long as the ratio to the total amount is 0.001% by weight or more and 3% by weight or less.

The particles insoluble in the reaction solution containing the norbornene monomer and the metathesis catalyst system have a particle size of 0.08 mm.
Not less than 0.6 mm and not more than 0.1 mm.
If it is 3 mm or less and is insoluble in a reaction stock solution containing a norbornene-based monomer and a metathesis catalyst system and is nearly spherical in shape, it is recognized as being useful in a reaction injection molding method using a reaction stock solution containing a norbornene-based monomer and a metathesis catalyst system. The particles present may, of course, be other.

When the shape of the particles is elongated, such as a rod, even if the cross section of the flow path is larger than the cross section of the particle, the flow path may block the flow path, and the shape of the mold is limited, which is practical. Not. As for the particle shape to be used, the aspect ratio is in the range of 1.5 or less, and the spherical shape is more preferable.

The insolubility of the particles in the reaction solution containing the norbornene-based monomer and the metathesis catalyst system is determined by dispersing the particles in the reaction solution at least immediately before molding. Is not necessarily insoluble as long as it has such a solubility that the particle size of 0.08 mm or more and 0.6 mm or less is maintained,
For example, the upper limit of the temperature of the normal reaction stock solution storage container is 3
Any particles that do not easily dissolve at 5 ° C. or less may be used.

Specific examples of the particles used in this embodiment include polyethylene, polystyrene, phenol resin, epoxy resin, acrylic resin, and vinyl chloride resin.

Since the particles used in the present embodiment are added in a small amount relative to the total amount, they may inhibit the bulk polymerization of the norbornene monomer and the metathesis catalyst system. When it is desired to terminate the reaction or when the degree of polymerization of the molded article obtained by the bulk polymerization needs to be at a very high level, a material which does not inhibit the bulk polymerization is desirable. For example, polyethylene is used. Furthermore, although the amount of particles added in the present embodiment is such that the material mechanical properties of the molded body do not change due to the addition of the particles,
In order to avoid the existence of a very small amount of voids to the extent that visual observation in the molded body is impossible by the addition of particles, for example, when there is no fluctuation before and after the addition of electrically insulating particles,
It is desirable that the particles be swollen and fused by the norbornene-based monomer during bulk polymerization. For example, medium-density and low-density polyethylene is used.

In this embodiment, the mold temperature is usually
It is room temperature or higher, preferably 40 to 200 ° C, particularly preferably 50 to 130 ° C. The components used for the polymerization reaction are preferably stored and operated under an atmosphere of an inert gas such as nitrogen gas.

The general polymerization time in the reaction injection molding method by bulk polymerization of a norbornene monomer and a metathesis catalyst system is shorter than 20 minutes, and desirably 5 minutes or less. When the bulk polymerization reaction proceeds rapidly after starting to flow out of the product part, the internal pressure inside the mold is kept above a certain level and the inside of the mold is kept under pressure. It is necessary to be shorter than the time, and the polymerization time in this embodiment is shorter than 3 minutes, and desirably 1 minute or less.

Further, in the present embodiment, when the bulk polymerization reaction starts to rapidly proceed when the undiluted reaction solution starts flowing out of the mold and flows into the liquid reservoir 4, the bulk polymerization reaction starts to progress. Immediately after that, the rise in viscosity is slight and the fluidity as a whole hardly changes because of the effect of the added particles in the part 5 flowing out to the liquid reservoir part 4 having a narrow flow path compared to the product part. The apparent viscosity of the stock solution rises sharply. As a result, the apparent viscosity of only the outflow portion increases while the overall fluidity is secured, and as a result, the pressure in the mold is automatically maintained.

In order for the internal pressure in the mold to be maintained at a certain level or more when the bulk polymerization reaction proceeds rapidly after the undiluted reaction solution starts flowing out of the product part of the mold, the inside of the mold must be maintained. Specifically, the viscosity of the reaction solution at the time when the reaction solution starts to flow out of the mold is increased by 20% or less, preferably by 10% or less, compared with the viscosity of the reaction solution before the reaction starts. A reaction stock solution is used. In addition, in order to increase the apparent viscosity of the reaction solution at the outlet with almost no change in the overall fluidity before the start of the reaction, a highly reactive reaction solution is used, specifically, The polymerization time is shorter than 3 minutes, preferably less than 1 minute.

If the level of the pressure in the mold is too low, the effect of preventing the generation of voids is reduced. Conversely, if the level of the pressure is too high, a large molding pressure is required especially for a large molded product. Is not practical. The range of internal pressure is usually 1.2
10 to 10 kgf / cm ² , preferably 1.5 to 7 kgf
/ Cm ² .

In order to increase the viscosity of the undiluted reaction solution to generate a dwelling pressure, the gap of the passage 5 from the cavity 6 to the liquid reservoir 4 shown in FIG. To 3.0 mm, more preferably 1.0 to 1.5
mm. If the gap is too small, it is not preferable because the flow of the reaction solution to the liquid reservoir 4 becomes difficult, and if the gap is too large, the rise in the viscosity of the reaction solution is small.

It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention.

For example, the method according to the present invention is suitable for use in a reaction injection molding method for norbornene-based monomers, but is not limited thereto, and may be used for other reaction injection molding.

[0064]

EXAMPLES Hereinafter, the present invention will be described based on more detailed examples and comparative examples, but the present invention is not limited to these examples. In the following description, parts or% are
Unless otherwise specified, weight is based.

Example 1 First, a mold shown in FIG. 1 was prepared. The mold is made of iron for both the cavity mold 2 and the core mold 1. The shape of the cavity 6 is such that the outer dimensions of the molded body are 20 cm × 50 cm, the average thickness is 5 mm, and the weight is about 0.5 kg. did. The liquid reservoir 4 was communicated with the cavity 6 via a passage 5 having a gap of 1.0 mm.

The preparation of the reaction stock solution was performed as follows. That is, 85% by weight of dicyclopentadiene (DCP)
And a mixed monomer comprising 15% by weight of tricyclopentadiene and 5 parts by weight of a styrene-isoprene-styrene block copolymer (Clayton 1170, manufactured by Shell Co., Ltd.), and 5 parts by weight of phenol-based Irganox 1010 which is an antioxidant
(Made by Ciba-Geigy) and 2 parts by weight thereof were put into two containers, and one of them was mixed with 40 mmol of diethylaluminum chloride (DEAC), 44 mmol of n-propanol, and tetrachloride with respect to the mixed monomer. Silicon was added to a concentration of 20 mmol (Solution A).
On the other hand, tri (tridecyl) ammonium molybdate was added to the mixed monomer at a concentration of 10 mmol (solution B).

On the other hand, low-density polyethylene spheres having a particle diameter of 0.1 mm as particles insoluble in a reaction stock solution containing a norbornene-based monomer and a metathesis catalyst system were added to the solution B as shown in Table 1, 0.1% by weight (described in Table 1 as the amount of PE spheres). Table 1
In Table 1, the particle size of the polyethylene sphere (described as the particle size of the PE sphere in Table 1) is the average particle size.

[0068]

[Table 1]

The two reaction stock solutions thus prepared were mixed at a ratio of 1: 1 using a collision mixing apparatus, and the mixture was poured into a mold heated to a cavity mold of 80 ° C. and a core mold of 50 ° C. from the injection port. Injected. The bulk polymerization reaction time was about 20 seconds.

Further, how the pressure in the mold was maintained was measured by a pressure sensor, and the result is shown in Table 1 as "inner pressure of mold". The internal pressure of the mold in Table 1 is kgf / cm ² . In Example 1, the internal pressure of the mold was 5.5 kgf / cm ² .

After the completion of the reaction, the molded body was taken out of the mold and the number of voids was measured. As a result, it was 3 as shown in Table 1. In addition, the number of voids of the molded body was counted by the following method.

The number of the voids having a diameter of 0.5 mm or more was counted by a method of counting the number of voids in a predetermined 10 cm × 10 cm square by watermarking the molded body into a 200 W light bulb.

Further, the glass transition temperature (T
g) was measured to be 150 ° C., the heat distortion temperature (HDT) was 120 ° C. (JIS K-6911, load 8.5 kg), the specific gravity was 1.01 g / cm ² , and the bending strength was 660 kg / mm. ^2. Flexural modulus is 17000kg / mm
² (JIS K-7203), Izod impact strength is 3
0 kg · cm / cm [JIS K-7110 6.5
(With notch)], and it was confirmed that it had rigidity and flexibility, was lightweight, and had excellent heat resistance and impact resistance.

Example 2 A molded article was produced in the same manner as in Example 1 except that a low-density polyethylene sphere having a particle diameter of 0.2 mm was used. The internal pressure of the mold and the number of voids were measured. Table 1 shows the results. The inner pressure of the mold is 6.2
kgf / cm ² and the number of voids was 3.

The measured values of the physical properties of the molded product were measured in the same manner as in Example 1, and the same measured values as in Example 1 were obtained. That is, the molded article of Example 2 also
It was confirmed that it had rigidity and flexibility, was lightweight, and had excellent heat resistance and impact resistance.

Example 3 A molded product was produced in the same manner as in Example 1 except that the amount of the low-density polyethylene spheres was 1% by weight based on the total amount of the reaction stock solution. Then, the internal pressure of the mold and the number of voids were measured. Table 1 shows the results. The internal pressure of the mold was 7.3 kgf / cm ² , and the number of voids was 3.

The measured values of the physical properties of the molded product were measured in the same manner as in Example 1, and the same measured values as in Example 1 were obtained. That is, the molded article of Example 3 also
It was confirmed that it had rigidity and flexibility, was lightweight, and had excellent heat resistance and impact resistance.

Example 4 A molded product was produced in the same manner as in Example 1 except that the amount of the low-density polyethylene spheres was 1% by weight based on the total amount of the reaction stock solution. Then, the internal pressure of the mold and the number of voids were measured. Table 1 shows the results. The internal pressure of the mold is 11.4 kgf / cm ² and the number of voids is 2
Met.

The measured values of the physical properties of the molded product were measured in the same manner as in Example 1, and the same measured values as in Example 1 were obtained. That is, the molded article of Example 4 also
It was confirmed that it had rigidity and flexibility, was lightweight, and had excellent heat resistance and impact resistance.

Comparative Example 1 A molded product was produced in the same manner as in Example 1 except that the amount of the low-density polyethylene spheres was 0% by weight based on the total amount of the reaction stock solution. Then, the internal pressure of the mold and the number of voids were measured. Table 1 shows the results. The internal pressure of the mold was 0 kgf / cm ² , and the number of voids was 30.

Comparative Example 2 A molded article was produced in the same manner as in Example 1 except that a low-density polyethylene sphere having a particle diameter of 0.05 mm was used. The internal pressure of the mold and the number of voids were measured. Table 1 shows the results. The inner pressure of the mold is 0.
It was 1 kgf / cm ² and the number of voids was 26.

As is clear from the results of Evaluation Table 1, Examples 1 to 4 of the present invention
Then, without using a special pressure-holding mechanism, by adding an appropriate amount of particles insoluble in the reaction solution containing norbornene-based monomer and metathesis catalyst system of an appropriate size, the bulk It can be seen that the internal pressure is maintained to greatly reduce the number of voids.

[0083]

As described above, according to the reaction injection molding method of the present invention, when a reaction injection molding is injected into a mold without providing a special pressure-holding mechanism in the mold.
The holding pressure of the reaction solution can be realized, and the number of voids generated in the molded body can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a mold used in a reaction injection molding method according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Core type 2 ... Cavity type 3 ... Seal groove 4 ... Liquid reservoir 5 ... Passage 6 ... Cavity

Claims (3)

[Claims] 1. A polymer solution having a particle diameter of 0.08 mm or more and 0.6 mm or less and insoluble in a reaction solution is added in an amount of 0.001 to 3% by weight based on the total amount of the reaction solution, and the reaction solution is used. A bulk injection polymerization in a mold. 2. A cavity defining a shape of a molded article,
A mold having an inlet serving as an inlet for injecting the reaction solution into the cavity, a liquid reservoir formed in communication with the uppermost position of the cavity, and a narrow passage communicating the cavity and the liquid reservoir; Is prepared, particles having a particle size of 0.08 mm or more and 0.6 mm or less and insoluble in the reaction stock solution are added to the reaction stock solution, and the reaction stock solution is passed through the passage from the injection port of the mold into the cavity. A reaction injection molding method characterized by filling the reaction solution until it flows into the liquid reservoir. 3. The method according to claim 1, wherein polymer particles having a particle size of 0.08 mm or more and 0.6 mm or less and insoluble in the reaction solution are added in an amount of 0.001 to 3% by weight based on the total amount of the reaction solution. Reaction stock solution.