JP4127196B2 - Reaction injection mold - Google Patents

Description

  The present invention relates to a reaction injection mold. More specifically, the present invention relates to a reaction injection mold that can manufacture a molded product while suppressing defects such as voids and unfilled.

A reaction injection (RIM) molding method, in which a raw material liquid composed of a norbornene monomer and a metathesis polymerization catalyst is mixed and injected into a mold composed of a convex mold and a concave mold to obtain a molded product, has been well known. For example, an outer tub of a household combined treatment septic tank is molded by a RIM molding method using dicyclopentadiene as a norbornene-based monomer. A mold used for such reaction injection molding usually has a reaction introduction part called a spool part, a runner part and a gate part. And the liquid mixture mixed with the mixing head is press-fitted into the cavity sequentially through the spool part, the runner part and the gate part. Conventionally, various studies have been made on the structure of the spool portion, the runner portion, and the gate portion so as not to cause an unfilled portion of the mixed liquid. For example, Patent Literature proposes a reaction injection mold having a film-shaped gate instead of a straight pipe-shaped gate portion. Patent Document 2 proposes a reaction injection molding die in which a film gate is formed into a flat film shape and is narrow at the center and wide at the end. However, in the conventional method, even if the gate opening thickness changes due to fluctuations in mold temperature and clamping pressure, it is difficult to adjust the gate opening accordingly. However, in the adjustment method, it was necessary to repeat the work of cutting the part, which was not an easy work.
JP-A-10-29228 JP 2002-46150 A

  An object of the present invention is to provide a reaction injection mold in which the gate opening can be easily adjusted, the injection pressure into the mold and the flow of the mixed liquid are controlled, and defects such as voids and unfilling can be prevented. The purpose is to provide.

As a result of various studies on the structure of the mixed liquid introduction part in order to achieve the above-mentioned problem, it has been found that it is effective to nest the gate part.
That is, the present invention relates to the following.
(1) A reaction injection mold for mixing a raw material liquid comprising a norbornene-based monomer and a metathesis polymerization catalyst, and pouring the obtained mixed liquid into a convex mold cavity and a concave mold cavity for reaction curing, wherein the injection section Is a structure in which a gate part is formed in the lower part of the mold, and a runner part and a spool part are formed in a substantially T shape in the lower part, and the gate part is a nested structure having a length equivalent to the cavity, By combining a plurality of inserts divided in the length direction according to the gate length, the thickness of the gate opening can be adjusted continuously or stepwise in the length direction. Reaction injection mold.
(2) The reaction injection molding die according to item (1), wherein a spacer is sandwiched between the nested structure and the die gate portion so that the thickness of the gate opening can be adjusted .
(3) The reaction injection mold according to item (2), wherein the spacer is an elastic body .
(4) The reaction injection mold according to item (3), wherein the elastic body is a spring .

  By using the reaction injection mold of the present invention, the gate opening can be easily adjusted, and a molded product free from molding defects can be easily produced from a norbornene monomer such as dicyclopentadiene.

Hereinafter, the present invention will be specifically described with reference to the drawings.
FIG. 1 is an external perspective view of a pair of reaction injection molds according to the present invention. The reaction injection mold is clamped, a plurality of raw material liquids are mixed by a mixing head under pressure, and the mixed liquid is injected into the cavities of the convex mold 1 and the concave mold 2 to be reacted and cured to obtain a molded product. It is done. As the material of the mold to be used, a metal mold is usually used, but synthetic resin, wood and the like can be used. The mold temperature is appropriately determined depending on the activity of the mixed solution, but is preferably 20 to 100 ° C, more preferably 35 to 85 ° C.

  FIG. 2 is a front view of the convex mold viewed from the concave mold of the pair of reaction injection molds according to the present invention. The injection part has a structure in which the gate part 3 is formed in the lower part of the mold, and the runner part 4 and the spool part 5 are formed in a substantially T shape in the lower part. Here, the reason why the gate portion 3 is disposed in the lower portion of the mold is that air or gas escapes upward in the cavity and does not generate voids or the like.

  The injection time of the mixed solution is 10 to 50 seconds, preferably 30 to 40 seconds, due to the characteristics of the molding material. This is because if the injection time is too long, the material hardens during the injection and an unfilled portion is generated, and if it is too short, air is easily involved.

The cross-sectional area of the spool portion 5 is determined from the ability of the pump for press-fitting the mixed liquid and the strength of the mold, and the discharge amount of the material is selected in accordance with the injection time. At this time, if the cross-sectional area of the spool portion is too small, the pressure applied to the mold increases, and the mold strength must be increased in order to withstand the pressure. Further, if the spool section has a large cross-sectional area, the material is likely to be wasted. Therefore, the injection pressure is 1 MPa or less, the injection speed is 5 to 15 m / s, and the cross-sectional area of the spool portion is about 100 to 300 mm ² .

  Although the length of the runner part 4 depends on the size of the molded product, it is about 10 to 100 times the width of the spool part. The cross-sectional area perpendicular to the mixed liquid flow in the runner part is designed to be about half of the cross-sectional area of the spool part. This is to prevent the mixed liquid that has exited the spool portion from colliding with the runner portion perpendicularly and separating into two directions in a T-shape, whereby the pressure is attenuated and the flow is disturbed.

  The material of the nesting used in the present invention is not limited, such as metal such as aluminum, stainless steel, iron, copper, nickel, fluorine resin such as polytetrafluoroethylene, plastic such as silicone, urethane, etc. The same thing is preferable. This is because, if the material is changed, the coefficient of thermal expansion is different, so that a gap is formed between the insert and the insertion groove, and the mixed solution may enter. The shape and size of the nesting are not limited as long as the shape / or thickness of the gate opening can be adjusted, and are appropriately determined according to the mold gate, but generally the cross-sectional shape is square or rectangular. A trapezoid, etc., having a width of 5 to 50 mm, a thickness of 1 to 30 mm, and a length of 100 to 3000 mm, preferably a width of 10 to 20 mm, a thickness of 3 to 10 mm, and a length of 200 to 1500 mm. The length of the nesting is preferably equal to the length of the cavity of the product part, and the thickness of the nesting may be varied continuously / stepwise. The nesting can be combined with a plurality of nestings in accordance with the gate length. This is because it is possible to make fine adjustments by exchanging the nesting partly. It is preferable that the number of nestings is usually 1 to 10, and the shape / thickness of each can be determined as appropriate. Furthermore, the thickness of the gate opening can be changed by inserting a spacer between the insert and the mold and changing the thickness of the spacer. Further, an elastic body or a spring can be used as the spacer. This is because the thickness of the gate can be adjusted by the elastic force simply by tightening or loosening the insert with a bolt or the like.

The norbornene-based monomer used in the present invention is a product obtained by performing a polymerization reaction in the presence of a metathesis polymerizable catalyst. The norbornenes include norbornene, norbornadiene, methylnorbornene, dimethylnorbornene, ethylnorbornene, ethylidenenorbornene, butylnorbornene, 5-acetyl-2-norbornene, dimethyl-5-norbornene-2,3-dicarboxylate, N-hydroxy -5-norbornene-2,3-dicarboximide, 5-norbornene-2-carbonitrile, 5-norbornene-2-carboxaldehyde, 5-norbornene-2,3-dicarboxylic acid monomethyl ester, 5-norbornene-2, 3-dicarboxylic acid dimethyl ester, 5-norbornene-2,3-dicarboxylic acid diethyl ester, 5-norbornene-2,3-dicarboxylic acid di-n-butyl ester, 5-norbornene-2,3-dicarboxylic acid Acid dicyclohexyl ester, 5-norbornene-2,3-dicarboxylic acid dibenzyl ester, 5-norbornene-2,3-dicarboxylic acid anhydride, 3,6-epoxy-1,2,3,6-tetrahydrophthalic acid anhydride, 5 -Bicyclic norbornene such as norbornene-2,3-dicarboxylic acid, 5-norbornene-2-methanol, 6-triethoxysilyl-2-norbornene, 5-norbornene-2-ol, dicyclopentadiene (dimer of cyclopentadiene) ), Dihydrodicyclopentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene, etc., tricyclic norbornene, tetracyclododecene, methyltetracyclododecene, tetracyclic norbornene, such as dimethylcyclotetradodecene, tricyclopentadiene ( Cyclopentadi Emissions of trimer), tetramer tetra cyclopentadiene (cyclopentadiene) and the pentacyclic or more norbornene like. These compounds may be used alone or in combination.
As the norbornene-based monomer, dicyclopentadiene is preferably used from the viewpoint of cost.

等のルテニウム化合物などがある。なお、上記において、Ｃ_６Ｈ_１１はシクロヘキシル基、Ｃ_６Ｈ_５はフェニル基、Ｃ_９Ｈ_１４はシメンを示す。 The metathesis polymerizable catalyst used in the present invention is a metathesis polymerizable catalyst capable of polymerizing norbornene monomers, and those known as catalysts for ring-opening polymerization of cycloolefin compounds can be used. Specific examples include halides such as tungsten, molybdenum and tantalum, oxyhalides, oxides, and organic ammonium salts. Suitable examples include tungsten hexachloride, tungsten oxytetrachloride, tungsten oxide, and tridodecyl. Tungsten compounds such as ammonium tungstate, tri (tridecyl) ammonium tungstate, trioctyl ammonium tungstate, etc .; molybdenum pentachloride, molybdenum oxytrichloride, tridodecyl ammonium molybdate, methyl tricaprylammonium molybdate, tri (tridecyl) ammonium Molybdate and other molybdenum compounds; tantalum compounds such as tantalum pentachloride,

And ruthenium compounds. In the above, C ₆ H ₁₁ represents a cyclohexyl group, C ₆ H ₅ represents a phenyl group, and C ₉ H ₁₄ represents cymene.

  Examples of the cocatalyst (activator) used in the present invention include alkylaluminum, alkylaluminum halide, alkoxyalkylaluminum halide, aryloxyalkylaluminum halide, organotin compound, etc. Suitable examples include triethylaluminum. , Triisobutylaluminum, trioctylaluminum, methylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminum chloride, ethylaluminum sesquichloride, propylaluminum dichloride, isobutylaluminum dichloride, methylaluminum sesquibromide, ethylaluminum dibromide, ethylaluminum diiodide , Diethylaluminum iodide, propyla Mini Umm diiodide, there is such as tetra-butyl tin.

  The above-mentioned metathesis polymerizable catalyst is usually used in an amount of about 0.01 to 50 mmol, preferably 0.1 to 20 mmol, per 1 mol of the norbornene monomer. The cocatalyst (activator) is generally used in an amount of 0.1 to 200 mol, preferably 1 to 10 mol, per 1 mol of the metathesis polymerizable catalyst component.

  The present invention will be described more specifically with reference to the following examples and comparative examples, taking as an example the case of producing a case of a septic tank weighing about 100 kg using a dicyclopentadiene-containing liquid as a raw material liquid.

(Example 1)
After the convex mold 1 made of aluminum casting and the concave mold 2 made of nickel electroforming are clamped, a two-component type raw material liquid is mixed by a mixing head under pressure, and the mixed liquid is put into the cavities of the convex mold 1 and the concave mold 2. The case can be formed by injection and reaction hardening. The mixture liquid is injected in about 35 seconds due to the characteristics of the molding material. The mold temperature is 40 ° C. for the convex mold and 80 ° C. for the concave mold. The gate portion 3 is formed in the lower portion of the mold, and the runner portion 4 and the spool portion 5 are formed in a substantially T-shape in the lower portion. FIG. 3 is a longitudinal sectional view after the convex mold and the concave mold are clamped. FIG. 4 is an enlarged view of the portion shown in FIG. 3A. The nest 7 divided into three shown in FIG. 5 is mounted in the groove 3 for nest mounting provided in the convex shape. The nest is fixed to the mold with bolts. The length of the nesting is 500 mm, and the total length of the nests is 1500 mm, which is the same as the gate length. The width of the nesting is 10 mm each. As for the thickness of the nesting, the nesting thickness (t2) at the center is 5 mm, and the nesting thicknesses (t1, t3) at both ends are 4.5 mm. The material of the nesting is aluminum. FIG. 6 shows an enlarged view of the part of FIG. 3A after the insert 7 is mounted on the mold. Thus, the cavity formed by the convex shape and the concave shape is as shown in FIG. 7, and its BB sectional view is as shown in FIG. The thickness of the gate opening 8 thus formed is about 0.5 mm at the center (t2 ′) and about 1.0 mm at both ends (t1 ′, t3 ′).
Further, the cross-sectional area S1 of the spool portion 5 is about 180 mm ² , the length of the runner portion 4 is 1500 mm, and the cross-sectional area S2 is 100 mm ² . The results of the septic tank molded product molded with the above mold are shown in Example 1 of Table 1.

(Comparative Example 1)
A molded product was obtained in the same manner as in Example 1 except that a insert with a thickness of 4.7 mm at the center and a thickness of 4.2 mm at both ends was used. The results are shown in Comparative Example 1 in Table 1.

(Comparative Example 2)
A molded product was obtained in the same manner as in Example 1 except that a insert with a thickness of 4.7 mm at the center and a thickness of 4.5 mm at both ends was used. The results are shown in Comparative Example 2 in Table 1.

表1に示すように型ゲート部の入れ子を入れ替えることで、ゲート開口部を容易に調整することができ、型内への注入圧及び混合液の流れを制御し、ボイド、未充填などの不具合を防ぐことができる。

By changing the nest of the mold gate as shown in Table 1, the gate opening can be easily adjusted, the injection pressure into the mold and the flow of the liquid mixture are controlled, and voids, unfilled defects, etc. Can be prevented.

The external appearance perspective view of a pair of reaction injection molding type | mold in one Example of this invention. The front view of the convex type in FIG. The longitudinal cross-sectional view after a convex mold and a concave mold clamp. The enlarged view of the FIG. 3A section. Nesting divided into three. FIG. 3B is an enlarged view of the portion shown in FIG. Cavity formed by convex and concave molds. BB sectional drawing of FIG.

Explanation of symbols

1: Convex type 2: Concave type 3: Gate part 4: Runner part 5: Spool part 6: Cavity of convex type 1 and concave type 2 7: Nest 8: Gate opening 9: Runner opening 10: Spool opening

Claims (4)

  A reaction injection mold for mixing a raw material liquid comprising a norbornene-based monomer and a metathesis polymerization catalyst, and injecting the obtained mixed liquid into a convex mold and a concave mold cavity and curing the reaction, wherein the injection section is a mold The gate portion is formed in the lower portion of the skirt, and the runner portion and the spool portion are formed in a substantially T-shape in the lower portion thereof. The gate portion is a nested structure having the same length as the cavity, and the length direction Reaction injection molding in which the thickness of the gate opening can be adjusted continuously or stepwise in the length direction by combining a plurality of nestings divided into two according to the gate length. Type. The reaction injection molding die according to claim 1, wherein a spacer is interposed between the nested structure and the die gate portion so that the thickness of the gate opening can be adjusted . The reaction injection mold according to claim 2, wherein the spacer is an elastic body . 4. The reaction injection mold according to claim 3, wherein the elastic body is a spring .

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