JP2005288772A - Foamed molding, its production method, and its molding apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a foamed molding which is light in weight and high in rigidity. <P>SOLUTION: In the method, at least two reaction solutions are supplied into a mold, polymerized, and cured in the mold. The gas concentration of the reaction solutions to be supplied into the mold is made below 0.02 wt.% at the start of the supply and changed to be 0.02-1 wt.% after the start of the supply to complete the supply. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a foamed molded article made of a cyclic olefin-based resin, a production method thereof and a molding apparatus.

  Conventionally, a reaction stock solution (Liquid A) containing a metathesis polymerization catalyst and a cyclic olefin monomer and a reaction stock solution (Liquid B) containing an activator and a cyclic olefin monomer are mixed and injected into the mold. A method is known in which a molded product is obtained by polymerization and molding. According to this method, a large molded body can be obtained relatively easily, and excellent advantages such as high rigidity and impact resistance of the obtained molded body can be obtained.

  By the way, in recent years, there has been a demand for reducing the weight of particularly large molded articles. As a method for reducing the weight of a large molded article, foam molding is known in which a foaming agent is added to a reaction stock solution for molding. As a method for producing a foamed molded article, a method is proposed in which gas is pressurized as a foaming agent and dissolved in a reaction stock solution, which is supplied into a mold and foamed during polymerization (Patent Document 1). ~ 2).

  However, the molded body obtained by the methods described in Patent Documents 1 and 2 is a uniform foamed product in which bubbles exist in the entire molded body. In this aspect, as the foaming rate increases, rigidity and resistance to linearity are increased. There is a tendency for impact properties to decrease. In addition, since the reaction stock solution in which the gas is dissolved in advance is used, it is difficult to adjust the foaming rate.

  On the other hand, for a period of time from the start of injection, a reaction stock solution (liquid A and liquid B) containing no foaming agent is supplied into the mold, first a skin layer is formed, and then a cyclic olefin monomer containing the foaming agent. As a third liquid (C liquid), a method is proposed in which an inner layer is formed between a pair of skin layers as a third liquid (C liquid) together with A liquid and B liquid (see Patent Document 3). .

However, in the method described in Patent Document 3, it is difficult to dissolve a sufficient amount of gas as a foaming agent in the liquid C. In addition, when a low-boiling compound or a capsule-like compound is used instead of gas as the foaming agent, the resulting bubble has a large diameter and tends to be non-uniform, so the rigidity and impact resistance of the resulting molded product Tended to decrease.
JP-A-10-58462 JP 2003-40983 A JP 7-178756 A

  An object of the present invention is to provide a lightweight and highly rigid foam molded article, a method for producing the same, and a molding apparatus suitable for realizing the method.

In order to achieve the above object, according to the present invention,
Supplying two or more reaction stock solutions into a mold, polymerizing the reaction stock solution in the mold and curing the foam molded article,
Provided is a method for producing a foamed molded article in which the gas concentration of a reaction stock solution supplied to a mold is set to less than 0.02% by weight at the start of supply, is switched to 0.02-1% by weight after the start of supply, and supply is completed The

  In the production method according to the present invention, it is preferable to contain 0.001 to 1% by weight of a surfactant in at least the reaction stock solution after switching the gas concentration.

  In the production method according to the present invention, the method for switching the gas concentration of the reaction stock solution is not particularly limited. For example, the gas concentration may be switched to 0.02 to 1% by weight at a certain timing after the start of supply, and the supply may be completed at that concentration. Alternatively, the gas concentration may be switched so as to gradually increase from the beginning (or the initial stage) of the supply to the completion of the supply.

  The production method according to the present invention is preferably applied in the case of producing a foamed molded article made of a cyclic olefin-based resin.

  The manufacturing method of the present invention described above can be realized by the following molding apparatus.

The molding apparatus according to the present invention includes:
Mold,
Reaction stock solution supply means for supplying the reaction stock solution to the mold;
A gas mixing means for containing a gas in the reaction stock solution before supplying the reaction stock solution from the reaction stock solution supply means to the mold;
Gas supply means for supplying gas toward the gas mixing means;
Recovery means for recovering a reaction stock solution containing gas that has not been supplied to the mold;
Degassing means for removing gas in the recovered reaction stock solution.

  In the molding apparatus according to the present invention, the reaction stock solution supply means is not particularly limited, and includes a tank for storing the reaction stock solution, a feed pipe from the tank to the mold, a valve, a pump, and the like. The recovery means includes a return pipe from the mold to the tank, a valve, a pump, and the like. Examples of the degassing means include a pressure reducing valve attached to a tank. When the removed gas is reused, it is preferable to separate the vaporized reaction stock solution component contained in the gas by cooling, compressing, adsorbing, or the like.

  It is preferable that a collision mixing means for mixing the reaction stock solution before being injected into the mold cavity is attached to the mold. The collision mixing means is not particularly limited, and examples thereof include a mixing head (also referred to as a mixing chamber).

  Although it does not specifically limit as reaction stock solution, In this invention, what contains a cyclic olefin monomer is used suitably.

  According to the present invention, a cyclic olefin resin having a skin layer having a specific gravity of 0.9 to 1.2 and an inner layer having a specific gravity of 0.5 to 0.9 (excluding 0.9). A foamed molded article is provided. In the foamed molded product according to the present invention, preferably, the inner layer includes bubbles having an average diameter of 100 μm or less.

  In addition, unless otherwise specified, "~" as used in this specification is the meaning which includes the numerical value described before and behind as a lower limit and an upper limit.

  According to the production method of the present invention, the gas as the foaming component can be intensively blended in the inner layer of the molded body. For this reason, a lightweight and highly rigid foam molded product can be obtained without impairing the physical properties of the entire molded product.

  Further, in this production method, by using a reaction stock solution containing an appropriate amount of a surfactant, the size of foaming (bubbles) generated by lowering the solubility of gas can be further reduced and distributed uniformly. As a result, further light weight and high rigidity can be realized.

  The molding apparatus according to the present invention has a recovery means and a degassing means. For this reason, while being able to collect | recover the reaction stock solutions containing the gas which was not supplied to the said metal mold | die, the gas in the reaction stock solutions containing this collect | recovered gas can be removed. As a result, it is possible to change the foaming rate of the molded body (for example, its inner layer) on the same line and make different molded bodies.

  Although it does not specifically limit as a foaming molding which concerns on this invention, A waterproof pan, a bathroom wall surface, a flooring, a windshield for motor vehicles, a bumper, a vehicle body cover for construction machines, a member for ships, a septic tank, etc. are illustrated.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 is a cross-sectional view showing a foamed molded product according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing an example of a molding apparatus suitable for manufacturing the foamed molded product of FIG. 1, FIG. FIG. 3B is a schematic view showing a partial modification of the molding apparatus of FIG.

Foamed molded first, with reference to FIG. 1, it will be described foam molded body 2.

  The foamed molded product 2 according to the present invention has an inner layer 6 between a pair of skin layers 4 and 4. The skin layer 4 and the inner layer 6 are both made of a cyclic olefin resin.

  The skin layer 4 has the specific gravity and physical properties inherent to the cyclic olefin resin and reinforces the physical properties of the entire molded body.

  The skin layer 4 has a specific gravity D1 of 0.9 to 1.2, preferably 0.92 to 1.1, more preferably 0.95 to 1.05. It is desirable that the skin layer 4 covers the entire surface of the foamed molded body 2 preferably at least 40%, more preferably at least 50%, and even more preferably at least 60%.

  The thickness T1 of each skin layer 4 is preferably 5 to 40%, more preferably 7.5 to 35% with respect to the thickness T2 of the entire molded body 2. If T1 is too thick, the inner layer 6 becomes too thin and weight reduction cannot be achieved. On the other hand, if T1 is too thin, the physical properties of the molded body are impaired and the rigidity is lowered.

  The inner layer 6 has a specific gravity D2 of 0.5 to 0.9 (excluding 0.9), preferably 0.6 to 0.85, more preferably 0.65 to 0.8 from the viewpoint of weight reduction. have.

  The inner layer 6 is a foam containing bubbles having an average diameter of 100 μm or less, preferably 80 μm or less, more preferably 50 μm or less, and weight reduction is achieved. If the bubbles contained in the inner layer 6 are too large, the strength of the molded body becomes fragile, which is not preferable. On the other hand, if the bubble size is too small, its production is difficult and the effect of reducing the weight is small, so the lower limit of the bubble size is preferably 1 μm. It is preferable that the majority of bubbles (approximately 70% or more) are independent.

  The above-mentioned bubble size (average diameter) is obtained by cutting the foamed molded product 2 of the present invention in the thickness direction, and observing this cut section with an electron microscope or the like at a magnification of 100 to 200 times. It is calculated by doing. Note that all the bubble sizes observed in the cut section are not the diameter of the bubbles. That is, when the bubble is a sphere, the cross section to be cut has various cut surfaces from the diameter portion of the sphere to the end of the sphere. Assuming that the bubbles are all perfect spheres of uniform size, the average diameter of the cut surface observed when randomly cut is approximately 0.74 times the diameter of the sphere. However, in the present invention, the above-mentioned “bubble size (average diameter)” means no simple correction or consideration, and means all simple average values of the cut surface observed with a microscope.

  The specific gravity D3 of the entire foamed molded body 2 is preferably 1.0 or less, more preferably 0.97 or less, and even more preferably 0.95 or less.

  The flexural rigidity (flexural modulus F) of the foamed molded product 2 is a value measured by a method according to JIS-K7203 from the viewpoint of not impairing physical properties, preferably 0.9 GPa or more, more preferably 1.2 GPa or more. More preferably, it is 1.4 GPa or more.

Method for producing a foamed molded Next, a method for manufacturing a foamed molded article 2.

  (1) First, a reaction stock solution is prepared. In the present invention, two or more reaction stock solutions such as A solution and B solution are used.

A liquid In this embodiment, A liquid contains a cyclic olefin monomer and a metathesis polymerization catalyst.

  Examples of the cyclic olefin monomer include those containing 1 to 2 metathesis polymerizable cycloalkene groups in the molecule. A compound having at least one norbornene skeleton in the molecule is preferable. Specific examples thereof include dicyclopentadiene, tricyclopentadiene, cyclopentadiene-methylcyclopentadiene codimer, 5-ethylidene norbornene, norbornene, norbornadiene, 5-cyclohexenyl norbornene, 1,4,5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 1,4-methano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethylidene -1,4,5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-ethylidene-1,4-methano-1,4,4a, 5,6 , 7,8,8a, -octahydronaphthalene, 1,4,5,8-dimethano-1,4,4a, 5,8,8a-hexahydronaphthalene, ethylenebis 5-norbornene) and the like can be illustrated, it may also be used a mixture thereof. In particular, dicyclopentadiene or a mixture containing 50 mol% or more, preferably 70 mol% or more thereof is suitably used.

  Further, if necessary, a cyclic olefin monomer having a polar group containing a different element such as oxygen or nitrogen can be used as a copolymerization monomer. This copolymerizable monomer also preferably has a norbornene structural unit. As the polar group, an ester group, an ether group, a cyano group, an N-substituted imide group, a halogen group and the like are preferable. Specific examples of the copolymerization monomer include 5-methoxycarbonylnorbornene, 5- (2-ethylhexyloxy) carbonyl-5-methylnorbornene, 5-phenyloxymethylnorbornene, 5-cyanonorbornene, and 6-cyano-1,4. , 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, N-butyl nadic acid imide, 5-chloronorbornene and the like.

  Examples of the metathesis polymerization catalyst include metal complexes such as tungsten, rhenium, tantalum, molybdenum, and ruthenium. Of these, tungsten compounds and molybdenum compounds are preferably used. As the tungsten compound, tungsten hexahalide, tungsten oxyhalide and the like are preferable, and tungsten hexachloride, tungsten oxychloride and the like are more preferable. In addition, organic ammonium tungstate can be used. As the molybdenum compound, molybdate organic ammonium salts such as tridodecyl ammonium molybdate and tri (tridecyl) ammonium molybdate are used.

  The amount of the metathesis polymerization catalyst used is, for example, when a tungsten compound is used as the catalyst component, and the ratio of the tungsten compound to the monomer is about 1,000 to 15,000 to 1, preferably 2,000 to 1, on a molar basis. It is around 1. If the amount of the metathesis polymerization catalyst used is too small, the polymerization activity is too low and the reaction takes time, so that the production efficiency is deteriorated. On the other hand, if the amount used is too large, the reaction becomes too intense, so that it is hardened before being sufficiently filled in the mold, and the catalyst is liable to precipitate, making it difficult to store it homogeneously.

  The metathesis polymerization catalyst is usually used after being dissolved in a monomer. However, when a tungsten compound is used as a metathesis polymerization catalyst, if it is added directly to the monomer, cationic polymerization starts immediately, which is not preferable. Therefore, it is preferable that the tungsten compound is used after being suspended in an inert solvent (for example, benzene, toluene, chlorobenzene, etc.) and solubilized by adding a small amount of an alcohol compound and / or a phenol compound.

  Further, as described above, in order to prevent undesired polymerization, it is preferable to add about 1 to 5 moles of Lewis base or chelating agent with respect to 1 mole of the tungsten compound. Such additives include acetylacetone, acetoacetic acid alkyl esters, tetrahydrofuran, benzonitrile and the like. In addition, when using a polar monomer, as mentioned above, it may be a Lewis base itself, and it may have the effect | action even if it does not add the above compounds in particular.

In addition, about the usage-amount of a chelating agent, according to the usage-amount of the said catalyst by experiment, it can adjust suitably and can use.
B liquid In this embodiment, B liquid contains the said cyclic olefin monomer and an activator.

  The activator (cocatalyst) is preferably an organometallic compound centered on an alkylated group I-III metal, particularly a tetraalkyltin, an alkylaluminum compound, or an alkylaluminum halide compound. Examples include diethylaluminum chloride, ethylaluminum dichloride, trioctylaluminum, dioctylaluminum iodide, and tetrabutyltin.

  When the alkylaluminum is used as the activator, the ratio of the aluminum compound to the monomer is about 100: 1 to 10,000: 1, preferably 200: 1 to 1,000 It is around 1.

  The activator is used by dissolving in a monomer. However, within the range that does not substantially impair the properties of the resulting molded body, it is difficult to precipitate by suspending in a small amount of solvent and mixing with the monomer, or using it with increased solubility. Also good.

  In the present invention, it is preferable to use an activity regulator together with the activator. By using an activity regulator in combination, the reaction rate, the time from mixing of the reaction solution to the start of the reaction, reaction activity, etc. can be changed, and curing occurs while the reaction solution does not flow sufficiently into the mold. Can be prevented.

  As the activity regulator, a compound having an action of reducing the metathesis polymerization catalyst is used. In general, Lewis bases are used, especially ethers, esters, nitriles and the like. Specific examples include ethyl benzoate, butyl ether, diglyme and the like. In addition, when using the monomer which has a Lewis base, it can also serve as the regulator.

  About the usage-amount of an activity regulator, it can adjust suitably according to the usage-amount of the said catalyst system by experiment, and can use it.

Surfactant In the present invention, it is preferable to add a surfactant to one or both of the A liquid and the B liquid for the purpose of stabilizing foaming by gas. As will be described later, this surfactant is preferably contained at least in the reaction stock solution after switching the gas concentration. However, it may be contained in the reaction stock solution before the gas concentration is switched.

  The surfactant is not particularly limited as long as it does not affect the polymerization reaction and does not adversely affect the molding. Specific examples of the surfactant include a fluorine-based surfactant and a silicone-based surfactant. Of these, fluorine-based surfactants are more preferable.

  Fluorosurfactant is a surfactant containing fluorine. Examples include fluorinated alkyl esters, fluorinated alkyl ester addition polymers, perfluoroalkyl-containing oligomers, perfluoroalkylethylene oxide, perfluoroalkyl. Examples thereof include ethylene oxide adducts, fluorinated methacrylate copolymers, and fluorinated acrylate copolymers.

  The silicone-based surfactant is a surfactant containing silicone, and examples thereof include polydioxyalkylene / dimethylpolysiloxane copolymer, polysilicone / polyether graft copolymer or block copolymer.

  The amount of the surfactant used is preferably 0.001% by weight to 2% by weight, more preferably 0.005% by weight to 1% by weight, and still more preferably 0.01% by weight with respect to the liquid A and the liquid B, respectively. ~ 0.5 wt%. By setting the amount to be used in this range, there is an effect of reducing the size of the bubbles in the foamed molded product and uniformly distributing the bubbles. If the amount used exceeds 2% by weight, it may remain as an unreacted substance in the molded body, thereby deteriorating the physical properties of the molded body. If the amount used is less than 0.001% by weight, the size of the bubbles in the foamed molded product tends to be small, and the effect of uniformly distributing the bubbles tends to be difficult to appear.

Optional components In the present invention, various optional components (antioxidants, other polymers, fillers, pigments, light stabilizers, flame retardants, polymer modifiers, etc.) may be added to one of liquid A and liquid B as desired. It can also be blended in both or another liquid (third liquid). Thereby, the characteristic of the obtained foaming molding can be improved or maintained. In particular, it is preferable to blend an antioxidant and / or another polymer.

  As antioxidant, a phenolic antioxidant and an amino antioxidant are preferable. Specific examples of these antioxidants include 2,6-di-t-butyl-p-cresol, N, N′-diphenyl-p-phenylenediamine, tetrakis [methylene (3,5-di-t-butyl- 4-hydroxycinnamate)] methane and the like.

  As the other polymer, an elastomer is preferable. The elastomer is effective in increasing the impact resistance of the molded product and adjusting the viscosity of the reaction stock solution. Specific examples of the elastomer include a wide range of elastomers such as styrene-butadiene-styrene triblock rubber, styrene-isoprene-styrene triblock rubber, polybutadiene, polyisoprene, butyl rubber, ethylene propylene-diene terpolymer, and nitrile rubber.

  Liquid A and liquid B are usually placed in separate tanks. The viscosities of the A liquid and the B liquid are usually about 5 to 3000 mPa · s, preferably about 100 to 1000 mPa · s at 30 ° C., for example.

  The liquid A and the liquid B alone do not cause polymerization of the cyclic olefin monomer, but polymerization occurs when the reaction stock solutions are mixed. The sum of the components contained in each reaction stock solution corresponds to the amount of components required for polymerization.

  When the above-mentioned optional component is included in the reaction stock solution, the polymerization of the cyclic olefin monomer may be substantially inhibited depending on the type of the optional component. In this case, in addition to liquid A and liquid B, a liquid (third liquid) containing an optional component is prepared and mixed with liquid A and / or liquid B as necessary and supplied to the mold. it can. Further, a method is conceivable in which a metathesis polymerization catalyst or activator is used as the third liquid, and optional components are added to the liquid A or liquid B not containing the liquid.

  In addition, when using a solid filler as an arbitrary component mentioned above, for example, it is not contained in the reaction stock solution, but can be put in the mold cavity in advance.

  (2) Next, two or more reaction stock solutions such as A solution and B solution are supplied into the mold, and the reaction stock solution is reacted in the mold for polymerization.

  Specifically, for example, liquid A and liquid B are mixed instantaneously using a collision mixing means such as a mixing head, and the mixed liquid is immediately supplied into the mold and reacted in the mold to be polymerized. .

  The supply pressure of the reaction stock solution (however, the pressure here is not the supply pressure to the mold, but the pressure in the feed pipe before the mixing head) is usually 2 to 15 MPa.

  In the present invention, a reaction stock solution containing substantially no gas having a gas concentration of less than 0.02% by weight is used as the reaction stock solution at the beginning of supply into the mold. This stock solution flows along the inner surface of the cavity formed inside the mold, and is polymerized and cured to form a pair of skin layers 4 (see FIG. 1).

  Thereafter, the gas concentration of the reaction stock solution is switched to 0.02 to 1% by weight to complete the supply. The reaction stock solution after switching flows between the pair of skin layers 4 in the cavity, and is polymerized and cured to form the inner layer 6 (see FIG. 1).

  If the gas concentration after switching is less than 0.02% by weight, the effect of weight reduction is small. On the other hand, if the gas concentration exceeds 1% by weight, the bubbles become too large or the bubbles are connected, and the strength of the resulting molded article is reduced.

  The gas used in the present invention may be any gas that acts as a foaming gas such as carbon dioxide gas, nitrogen gas, argon gas, helium gas, but is preferably nitrogen gas or carbon dioxide gas, particularly preferably nitrogen gas. It is.

  The timing for switching the gas concentration is usually when a reaction stock solution in an amount capable of forming the skin layer 4 is supplied into the mold, but it may slightly vary depending on the volume and shape of the mold cavity. What is necessary is just to adjust suitably.

  In order to switch the gas concentration, the amount of gas to be mixed and dissolved in the reaction stock solution may be increased.

  The method for switching the gas concentration is not particularly limited. For example, the gas concentration may be switched to 0.02 to 1% by weight at a certain timing after the start of supply, and the supply may be completed at that concentration. Alternatively, the gas concentration may be switched so as to gradually increase from the beginning (or the initial stage) of the supply to the completion of the supply.

  The method for mixing the gas into the reaction stock solution is not particularly limited. For example, even if gas is introduced at a predetermined pressure (for example, about 1 to 10 MPa) into a tank that stores a reaction stock solution (A solution and / or B solution), and the gas is mixed with the reaction stock solution in the tank. good. Also, gas mixing means such as a gas mixing device is provided in the feed pipe from the tank to the mixing head, not to the tank storing the reaction stock solution, and gas is supplied from the gas supply means (gas tank and pump). May be introduced at a predetermined pressure (for example, about 2 to 20 MPa), and a gas may be mixed with the reaction stock solution. In the former case, each of liquid A and liquid B requires four tanks, a tank containing gas and a tank not containing gas. In particular, the tank into which the gas is introduced must have a pressure-resistant structure. On the other hand, in the latter case, only two tanks for storing the A liquid and the B liquid and three tanks for the gas tank are required, and the two tanks for storing the A liquid and the B liquid do not need to have a pressure-resistant structure. In the present invention, the latter case is preferable.

  The method for dissolving the gas in the reaction stock solution is not particularly limited. For example, when dissolving only by applying pressure at normal temperature, the gas can be supplied to the tank by a gas supply means provided with a pressurizing device and the tank can be pressurized. For example, it can be performed by applying a pressure of 6 MPa or more in about 10 hours, or applying a pressure of 8 MPa or more in about 3 to 5 hours. In addition, the gas is introduced from the gas supply means to the gas mixing device provided in the feed pipe from the tank to the mixing head while liquefying or densifying the gas as an extremely low temperature and applying a predetermined pressure, The gas may be dissolved in the reaction stock solution at a predetermined pressure (for example, about 2 to 20 MPa). For example, it can also be performed by introducing a gas having a pressure of 6 MPa or more and a temperature of −60 ° C. In the present invention, the latter case is preferred.

  The pressure for dissolving the gas is not less than the pressure of the reaction stock solution, preferably not less than the pressure of the reaction stock solution +0.5 MPa, and is preferably higher, but is preferably 2 to 20 MPa, more preferably 5 to 18 MPa from a practical point of view. It is. The temperature at which the gas is dissolved is preferably 5 to 40 ° C.

  For the inner layer 6 formed by the polymerization after the gas concentration is switched to 0.02 to 1% by weight and the supply is completed, the solution state and / or the polymerization reaction just before solidifying in the mold proceeds. Foaming proceeds at one or both of the stages where the viscosity is increasing. The reaction stock solution containing the gas supplied into the mold to form the inner layer 6 is subjected to a rapid pressure and / or temperature change in the mold, and the solubility of the gas is lowered and foams. In this case, either the pressure or temperature in the mold may be changed. However, when the gas is dissolved in the reaction stock solution by high pressure, a mold having pressure adjusting means such as a pressure adjusting valve is used. It is preferable to control so that the pressure in the mold is rapidly decreased by the pressure adjusting means.

  Although the temperature and pressure of the mold are controlled, the mold temperature rapidly rises due to the polymerization reaction of the reaction stock solution, and the pressure in the mold also changes. Such rapid changes in temperature and pressure also contribute to foaming.

The mold clamping pressure of the mold is usually in the range of 0 to 100 × 10 ⁵ Pa.

  The mold temperature is preferably set in the range of 20 ° C to 120 ° C, more preferably 30 ° C to 110 ° C, immediately before the start of the polymerization reaction.

  In order to adjust the solubility change of the gas in the reaction stock solution and obtain a desired bubble state, the inside of the mold is pressurized (pre-pressurized) with a gas that does not substantially affect the cross-linking polymerization reactivity of the cyclic olefin monomer. The pressure in the mold is preferably adjusted to be constant in the range of 0.01 to 0.95 MPa, more preferably 0.02 to 0.8 MPa, and even more preferably 0.04 to 0.6 MPa. desirable. Such a gas is preferably an inert gas, more preferably nitrogen, argon or carbon dioxide, and nitrogen is particularly preferable from the viewpoint of cost. If the pressure in the mold is too low, there is no effect, and if it is too high, foaming may be insufficient.

  On the other hand, in addition to changing the temperature, either the pressure or the temperature may be changed from the outside. However, when the gas is dissolved in the reaction stock solution by high pressure, a pressure adjusting means such as a pressure adjusting valve is provided. It is preferable to control the pressure in the mold so as to be kept as constant as possible by using this pressure adjusting means.

  In the present invention, for example, when mixing two or more reaction stock solutions with a mixing head or the like, the temperature of each reaction stock solution is preferably in the range of 10 ° C to 45 ° C, more preferably 15 ° C to 30 ° C. As described above, it is preferable to adjust the temperature of the tank, piping, and the like.

The polymerization time may be appropriately selected, but is generally about 20 seconds to 10 minutes after the completion of the injection of the reaction solution.
The material of the mold to be used is not particularly limited, and is not limited to metals such as stainless steel, aluminum, and nickel electroforming, but may be 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.

  By opening the mold at the stage where the polymerization (reaction injection molding) in the cavity is completed and the molded body is solidified, the foamed molded body 2 having the structure shown in FIG. 1 can be obtained.

Molding Apparatus Next, a molding apparatus 20 as an example for realizing the above manufacturing method will be described with reference to FIG. The molding apparatus 20 has a single mold 22. The mold 22 may include a pressure adjustment valve (not shown) that can adjust the pressure in the mold. A cavity (not shown) for forming the foamed molded body 2 shown in FIG. 1 is formed inside the mold 22. A mixing head 24 is attached to the mold 22. The mixing head 24 is connected to feed pipes from the first reaction stock solution tank 26 and the second reaction stock solution tank 28.

  The apparatus 20 according to this embodiment includes at least two reaction stock solution tanks 26 and 28 and at least one gas tank 30. The tank 26 stores a reaction stock solution A, the tank 28 stores a reaction stock solution B, and the gas tank 30 stores a gas acting as a foaming gas.

  Each feed pipe 32, 34, 36, 38 is connected to each tank 26, 28, 30. These feed pipes 32, 34, 36, 38 are equipped with pumps 40, 42, 44, 46 as supply means, respectively, so that the liquid or gas in these tanks can be sent in the direction of the mold 22. It has become.

  A first gas mixing device 48 and a second gas mixing device 50 are provided as gas mixing means at positions where the feed pipes 32, 34 and the feed pipes 36, 38 on the downstream side of the pumps 40, 42 and the pumps 44, 46 intersect. It is. Each mixing device 48, 50 continuously mixes each reaction stock solution supplied from the tanks 26, 28 and the gas supplied from the tank 30 at a predetermined pressure so as to continuously dissolve the gas in each reaction stock solution. It is configured. The inside of each mixing device 48, 50 is maintained at a predetermined pressure in order to effectively dissolve the gas in each liquid.

  The tank 30 as a part of the gas supply means may be provided with a mechanism for cooling the gas stored therein to an extremely low temperature (for example, about −60 ° C.). As a result, the gas can be liquefied or densified at a very low temperature and introduced into the mixing devices 48 and 50.

  Control valves 52 and 54 are provided in the feed pipes 32 and 34 on the downstream side of the mixing devices 48 and 50 and in front of the mixing head 24. The control valves 52 and 54 are three-way valves, and a state in which the reaction stock solution supplied from the tanks 26 and 28 is sent in the direction of the mixing head 24 and a state in which the reaction stock solutions are sent in the directions of the return pipes 56 and 58, At the same time that the liquid is fed in the direction of the mixing head 24, the state is switched to the state in which the liquid is also fed in the directions of the return pipes 56 and 58. In FIG. 2, the control valves 52 and 54 are in a state in which the reaction stock solution from the tanks 26 and 28 is sent to the return pipes 56 and 58.

  Each return pipe 56, 58 can return the reaction stock solution to each tank 26, 28.

  The tanks 26 and 28 are provided with, for example, a pressure reducing valve (not shown) as a degassing means, and the gas dissolved in each liquid returned through the return pipes 56 and 58 can be removed. Further, the vaporized reaction stock solution component contained in the removed gas may be separated by cooling, compression or adsorption, and the gas may be returned to the tank 30 for reuse.

  The control valves 52 and 54 are preferably connected as close to the mixing head 24 as possible in the feed pipes 32 and 34, and more preferably within 5 m. Moreover, the distance between the mixing head 24 and the mold 22 is preferably as short as possible, and more preferably within 2 m.

  The tanks 26 and 28 may be provided with a temperature sensor and temperature adjusting means (both not shown). The internal temperature data of each tank measured by the temperature sensor is sent to a control device (not shown), and a temperature adjustment signal is sent based on the temperature data. The internal temperature can be controlled. Note that it is also preferable to provide temperature adjusting means for the pipes 32, 34, 56, and 58. The internal temperature of each tank 26, 28 is adjusted so that the temperature of the reaction stock solution when injected into the mold 22 is preferably in the range of 10 to 45 ° C, more preferably 15 to 30 ° C. Is preferred.

  At the time before reaction injection molding starts, the control valves 52 and 54 return all of the reaction stock solution from the tanks 26 and 28 to the tanks 26 and 28 through the return pipes 56 and 58.

  In order to start reaction injection molding, the control valves 52 and 54 are controlled so that all of the reaction stock solution sent from the tanks 26 and 28 is fed into the mixing head 24 where the reaction stock solution is collided and mixed. At the same time, injection into the cavity of the mold 22 is started. The reaction stock solution injected into the cavity reaches the inside of the cavity.

  After injecting into the cavity until the amount capable of forming the skin layer 4 (see FIG. 1) is reached (approximately 0.1 to 25 seconds after the start of injection), the liquid A stored in the tank 26 is pumped 40 Is supplied to the first gas mixing device 48 at a predetermined pressure, and the gas stored in the tank 30 is supplied to the first gas mixing device 48 at a predetermined pressure by the pump 44. At the same time, the liquid B stored in the tank 28 is supplied to the second gas mixing device 50 at a predetermined pressure by the pump 42 and the gas stored in the tank 30 is mixed at the predetermined pressure by the pump 46. Supply to device 50. In the mixing devices 48 and 50, each liquid and gas are collided and mixed, and the gas is continuously dissolved in each liquid by pressurization and / or heating. The supply amount of the gas is adjusted so as to be 0.02 to 1% by weight in total with respect to the whole of the liquid A and the liquid B.

  Then, the liquid A in which the gas is dissolved in the first gas mixing device 48 and the liquid B in which the gas is dissolved in the second gas mixing device 50 are sent into the mixing head 24 where they are collided and mixed. At the same time, injection into the cavity of the mold 22 is started.

  After approximately 30 seconds from the start of injection, the injection into the cavity is completed, and after the polymerization reaction is completed, the mold 22 is decompressed to room temperature and opened to form an inner layer formed between the pair of skin layers. The molded body 2 can be obtained.

  On the other hand, when the injection into the cavity is completed, the control valves 52 and 54 are controlled to close the flow path to the mixing head 24 and are not supplied to the mold 22 but into the feed pipes 32 and 34. The remaining reaction stock solution containing gas is recovered into the tanks 26 and 28. At this time, the pressure reducing valves (not shown) provided in the tanks 26 and 28 are opened, and the gas dissolved in the liquid is removed.

  In the molding apparatus 20 of the present embodiment, since the control valves 52 and 54 and the return pipes 56 and 58 are provided, the control valves 52 and 54 and the return pipes 56 and 58 are not supplied to the mold 22 and in the feed pipes 32 and 34 on the downstream side of the mixing apparatuses 48 and 50. The reaction stock solution containing gas remaining in the tanks 26 and 28 can be recovered. Since the tanks 26 and 28 are provided with degassing means such as a pressure reducing valve (not shown), the gas in the reaction stock solution including the recovered gas can be removed from the liquid. As a result, it is possible to change the foaming rate of the inner layer 6 on the same line and make different shaped bodies.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in various aspects. .

  For example, in the molding apparatus 20 shown in FIG. 2, the control valves 52 and 54 are not provided in the feed pipes 32 and 34, but are supplied from the tanks 26 and 28 as shown in FIGS. 3 (A) and 3 (B). A mixing head 24a having a structure capable of switching the flow direction of the reaction stock solution to be used may be used.

  Hereinafter, the present invention will be described based on further detailed examples, but the present invention is not limited to these examples. Unless otherwise indicated, the part and% in an Example and a comparative example are a basis of weight.

Example 1
Preparation of solution A as a reaction stock solution Twenty parts of tungsten hexachloride was added to 70 parts of dry toluene in a nitrogen stream, and then a solution consisting of 2 parts of nonylphenol and 16 parts of toluene was added to a concentration of 0.5 mol / liter. A tungsten-containing catalyst solution was prepared.

  Next, this tungsten-containing catalyst solution is purged with nitrogen gas overnight to remove hydrogen chloride gas produced by the reaction of tungsten hexachloride and nonylphenol. Part of acetylacetone was added to prepare a polymerization catalyst.

  Next, with respect to a monomer mixture consisting of 95 parts of purified dicyclopentadiene (purity 99.7%, the same applies hereinafter) and 50 parts of purified ethylidene norbornene (purity 99.5%, the same applies hereinafter), ethylene-containing 70 mol% ethylene- A reaction stock solution containing a catalyst component by adding the above polymerization catalyst solution to a solution containing 3 parts of propylene-ethylidene norbornene polymer rubber and 2 parts of Etanox 702 as an oxidation stabilizer so that the tungsten content becomes 0.01 mol / liter. (Liquid A) was prepared.

  Further, 0.02 part of 3M surfactant Fluoride FC-740 was added to 100 parts of Liquid A. Solution A had a viscosity of 300 cps at 30 ° C.

Preparation of solution B as a reaction stock solution 95 parts of purified dicyclopentadiene, 5 parts of purified ethylidene norbornene, ethylene are prepared by mixing and adjusting a polymerization activator mixed solution at a molar ratio of trioctyl aluminum 85, dioctyl aluminum iodide 15, and diglyme 100. A reaction stock solution (solution B) containing an activator component mixed with a monomer mixture composed of 3 parts of 70 mol% ethylene-propylene-ethylidene norbornene polymer rubber at a ratio of aluminum to 0.03 mol / liter Was prepared.

  Further, 0.02 part of 3M Surfactant Fluoride FC-740 was added to 100 parts of Liquid B. Solution B had a viscosity of 300 cps at 30 ° C.

As the foaming gas , nitrogen gas whose pressure was increased to 5.5 MPa was used.

Molding apparatus 20 shown in FIG. 2 is filled with A liquid and B liquid in a nitrogen atmosphere, respectively, and the feeding speeds of A liquid and B liquid are 200 g / second and 200 g / second, respectively. 2.2 seconds after the B liquid enters the mold 22 through the mixing head 24, the foaming gas is sent out from the nitrogen mixer (gas supply device 30) and dissolved in the A and B liquids by the mixing devices 48 and 50. Then, the liquid A and liquid B containing 0.1% of pressurized nitrogen are passed through the mixing head 24 into the mold 22 pressurized to 0.4 MPa with nitrogen and set so that the total liquid injection time is 5.0 seconds. And then molded.

  The mold 22 uses an iron mold having a plate-like space (cavity) of 550 mm × 550 mm × 6 mm, and the supply component exceeding the amount filling the space overflows in the container provided at the mold 22 outlet. It came out. The mold temperature was 90 ° C. on one side and 60 ° C. on the other side in advance. The mold was opened 90 seconds after the supply was completed, and the molded body was taken out.

  Bubbles (bubbles) were not observed on the surface of the removed molded body and were smooth. That is, almost 100% of the surface was covered with the skin layer.

  Next, when the molded body was cut and its cross section was examined, a non-foamed layer having a thickness of 0.5 mm as a skin layer and a foamed layer as an inner layer were observed inside.

  Next, the obtained molded body was cut out, and the specific gravity D1 of the skin layer, the specific gravity D2 of the inner layer, the total specific gravity D3, the size (average diameter) of the bubbles in the inner layer, and the flexural modulus F were measured. As a result, D1 = 1.03, D2 = 0.814, D3 = 0.85, bubble size = 35 μm, and F = 1.6 GPa.

  The “flexural modulus F” of the molded body was measured by a method based on JIS-K7203. The “bubble size (average diameter)” was calculated as follows. First, the obtained molded body is cut out in the thickness direction. Three 1 mm × 0.8 mm square portions in the cut section are extracted arbitrarily. The extracted three places are observed with an electron microscope at a magnification of 100 times. Randomly select 20 bubbles from the observed bubbles. Each of the selected 20 bubble sizes is measured. The average value of 20 measured values is calculated.

Example 2
Using the same molding apparatus 20 as in Example 1, the feeding speeds of liquid A and liquid B were 300 g / second and 300 g / second, respectively, and liquid A and liquid B entered the mold 22 through the mixing head 24. After 5 seconds, the blowing agent is sent out from the nitrogen mixer (gas supply device 30), dissolved in the liquids A and B by the mixing devices 48 and 50, and the liquids A and B containing 0.2% pressurized nitrogen are mixed. It put into the metal mold | die 22 pressurized to 0.6 MPa with nitrogen through the head 24, set it so that the total liquid injection | pouring time might be set to 3.3 second, and took out the molded object.

  Bubbles (bubbles) were not observed on the surface of the removed molded body and were smooth. That is, almost 100% of the surface was covered with the skin layer.

  Next, when the molded body was cut and its cross section was examined, a non-foamed layer having a thickness of 0.5 mm as a skin layer and a foamed layer as an inner layer were observed inside.

  Next, the obtained molded body was cut out, and the specific gravity D1 of the skin layer, the specific gravity D2 of the inner layer, the total specific gravity D3, the size (average diameter) of the bubbles in the inner layer, and the flexural modulus F were measured. As a result, D1 = 1.03, D2 = 0.814, D3 = 0.85, bubble size = 36 μm, and F = 1.55 GPa.

Example 3
2. Using the same molding apparatus 20 as in Example 1, the feeding speeds of liquid A and liquid B were 150 g / second and 150 g / second, respectively, and liquid A and liquid B entered the mold 22 through the mixing head 24. After 0 seconds, the blowing agent is sent out from the nitrogen mixer (gas supply device 30), dissolved in the liquids A and B by the mixing devices 48 and 50, and the liquids A and B containing 0.05% pressurized nitrogen are mixed. Through the head 24, it was put into a metal mold 22 pressurized to 0.1MPa with nitrogen, and was molded so that the total liquid injection time was set to 6.7 seconds, and the molded body was taken out.

  Bubbles (bubbles) were not observed on the surface of the removed molded body and were smooth. That is, almost 100% of the surface was covered with the skin layer.

  Next, when the molded body was cut and its cross section was examined, a non-foamed layer having a thickness of 0.5 mm as a skin layer and a foamed layer as an inner layer were observed inside.

  Next, the obtained molded body was cut out, and the specific gravity D1 of the skin layer, the specific gravity D2 of the inner layer, the total specific gravity D3, the size (average diameter) of the bubbles in the inner layer, and the flexural modulus F were measured. As a result, D1 = 1.03, D2 = 0.79, D3 = 0.83, bubble size = 35 μm, and F = 1.6 GPa.

Comparative Example Using the same molding apparatus 20 as in Example 1, the feeding speeds of liquid A and liquid B were 300 g / second and 300 g / second, respectively, and the blowing agent was fed out from the nitrogen mixer (gas supply device 30) and mixed. A mold 22 in which A and B liquids containing 0.1% of pressurized nitrogen are pressurized to 0.4 MPa with nitrogen through the mixing head 24 from the beginning by dissolving them in the A and B liquids using the devices 48 and 50. And molding was carried out so that the total liquid injection time was set to 5.0 seconds, and the molded body was taken out.

  Innumerable tiny bubbles (bubbles) were observed on the surface of the molded body taken out. That is, no part of the surface was covered with the epidermis layer.

  Next, when the molded body was cut and its cross section was examined, the whole was composed of a foam layer (corresponding to the inner layers of Examples 1 to 3).

  Next, the obtained molded body was cut out, and the specific gravity D3 of the entire molded body, the size (average diameter) of bubbles in the molded body, and the flexural modulus F were measured. As a result, D3 = 0.85, bubble size = 39 μm, and F = 1.3 GPa. That is, it was confirmed that the bubble size was large and the flexural modulus F was inferior compared with Examples 1-3.

Table 1 shows the results of Examples 1 to 3 and the comparative example described above.

FIG. 1 is a cross-sectional view showing a foam molded article according to an embodiment of the present invention. FIG. 2 is a schematic view showing an example of a molding apparatus suitable for producing the foam molded article of FIG. 3A and 3B are schematic views showing a partial modification of the molding apparatus of FIG.

Explanation of symbols

2 ... Foam molded body 4 ... Skin layer (non-foamed layer)
6 ... Inner layer (foamed layer)
20 ... Molding device 22 ... Mold 24, 24a ... Mixing head (collision mixing means)
26 ... First reaction stock solution tank (reaction stock solution supply means)
28 ... Second reaction stock solution tank (reaction stock supply means)
30 ... Gas tank (gas supply means)
32, 34, 36, 38 ... feed pipes 40, 42, 44, 46 ... pump 48 ... first gas mixing device (gas mixing means)
50 ... Second gas mixing device (gas mixing means)
52, 54 ... Control valves 56, 58 ... Return piping (recovery means)

Claims (6)

Supplying two or more reaction stock solutions into a mold, polymerizing the reaction stock solution in the mold and curing the foam molded article,
A method for producing a foamed molded article, wherein the gas concentration of a reaction stock solution supplied to a mold is set to less than 0.02% by weight at the start of supply, is switched to 0.02-1% by weight after the start of supply, and the supply is completed. The manufacturing method of the foaming molding of Claim 1 which makes 0.001 to 1weight% of surfactant contain in the reaction stock solution after switching gas concentration at least. The manufacturing method of the foaming molding of Claim 1 or 2 which a foaming molding consists of cyclic olefin resin. Mold,
Reaction stock solution supplying means for supplying the reaction stock solution to the mold;
A gas mixing means for containing a gas in the reaction stock solution before supplying the reaction stock solution from the reaction stock solution supply means to the mold;
Gas supply means for supplying gas toward the gas mixing means;
Recovery means for recovering a reaction stock solution containing gas that has not been supplied to the mold;
And a degassing means for removing gas in the recovered reaction stock solution. A foam-molded article made of a cyclic olefin resin, having a skin layer having a specific gravity of 0.9 to 1.2 and an inner layer having a specific gravity of 0.5 to 0.9 (excluding 0.9). The foaming molding of Claim 5 in which the said inner layer contains the bubble which has an average diameter of 100 micrometers or less.

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