KR100492664B1 - Injection molding of epoxy resin compositions capable of injection molding, and epoxy resin moldings using the same - Google Patents

Abstract

The present invention provides an injection molding method for an epoxy resin molded article capable of shortening the molding cycle and continuously molding the epoxy resin composition, and minimizing the waste part after curing, and an injection molding machine. Provided is an injection moldable epoxy resin composition having excellent thermal stability without curing in a cylinder and having latent curing characteristics in which a curing reaction proceeds rapidly in a mold.

The molding method is composed of a manifold portion, a mini sprue portion, and an ejector plate portion, and the mold temperature of the manifold portion is set to a temperature at which the epoxy resin composition is melted and hardening is not accelerated. Injection molding using an epoxy resin composition having a.

Description

Injection molding epoxy resin composition, and injection molding method of the epoxy resin molded article using the same

The present invention relates to an injection molding method of an epoxy resin molded article and an epoxy resin composition capable of injection molding, and more particularly, to an injection molding method of an epoxy resin molded article using a mini sprue mold, and an injection molding capable of curing properties of a latent mold suitable thereto. It relates to an epoxy resin composition.

Since epoxy resins are excellent in various physical properties such as heat resistance, abrasion resistance, and chemical resistance, it is well known that they are used in many applications.

The transfer molding method is known as a suitable shaping | molding method from the viewpoint of the productivity of an epoxy resin molding material conventionally. In the transfer molding, the epoxy resin composition is introduced into a pot in the mold before molding, and it is generally pressurized with a plunger to flow harden the mold.

However, in this molding method, it is necessary to tablet the molding material first and also require a preheating step. Therefore, the molding cycle can not be shortened by a certain number or more, and thus there is a limit in terms of productivity and low cost. In addition, transfer molding has a problem that curls remaining in the pot other than the runner are generated as wastes after curing.

The cured curls cannot be reused normally and are discarded as they are, but they are not decomposed even if discarded, which is a cause of environmental pollution.

On the other hand, the injection molding method generally inserts a thermoplastic resin molding material powder into a hopper, and after the preheating and metering is performed automatically in a cylinder, it is injected into a mold and cured. Therefore, in this case, the process of tableting the molding material and the preheating process are unnecessary, and the continuous production is possible, so that the molding cycle can be shortened compared to the transfer molding, which is an excellent method in terms of production efficiency.

However, the epoxy resin molding material used in the conventional transfer molding has poor thermal stability in the cylinder, and the melt viscosity increases so much that injection molding cannot be performed.

As a mold for injection molding epoxy resin, conventional general injection molding molds and mini sprue molds including a manifold portion, a mini sprue portion, and an ejector plate portion shown in FIG. 2 are known. Since the portions corresponding to the Furu mold manifold portions are temperature-controlled to promote the curing of the resin as sprues and runners, the entire manifold portion and the sprue portion are taken out in the hardened state at each molding cycle. .

This problem of injection molding can occur similarly in transfer molding, and the curl part or the runner part is taken out in a hardened state together with the molded part because the entire mold is maintained at a temperature at which hardening is accelerated.

However, since the epoxy resin is a thermosetting resin, once cured, it cannot be reused like a thermoplastic resin. Therefore, the hardened portion other than the product generated with molding must be discarded as it is. In addition, epoxy resins have a longer molding cycle than thermoplastic resins, and there are many problems to be improved in terms of productivity.

In other words, the molding material using epoxy resin has a low commercialization rate with respect to the amount of resin used, and there is a problem of discharging industrial waste accompanying environmental pollution as well as an economic problem of poor productivity.

Accordingly, an object of the present invention is to provide an injection molding method that can solve the problems of the conventional epoxy resin by improving the productization rate and shortening the molding cycle in the molding of the molding material using the epoxy resin.

Another object of the present invention is to provide an injection moldable epoxy resin composition having excellent curing properties without curing in a cylinder and excellent curing properties in a mold.

The present invention has been proposed in order to achieve the above object, a method of injection molding using a mini sprue mold using an epoxy resin as a material polymer, and the specific gel time and melt viscosity characteristics suitably used in the molding method. It is characterized by the epoxy resin composition which shows, or the epoxy resin composition which has specific gel time and the activation energy of reaction.

That is, according to the present invention, it is composed of a manifold portion, a mini sprue portion, and an ejector plate portion, and the mold temperature of the manifold portion is set to a temperature at which the epoxy resin composition is melted and hardening is not promoted. Provided is a molding method of an epoxy resin molded article characterized by injection molding using an epoxy resin composition having curing properties.

According to the present invention, there is also provided a molding method of the epoxy resin molded article wherein the mold temperature of the manifold portion is set at a temperature of 90 to 130 占 폚 lower than the mold temperature of the mini sprue portion.

According to the present invention, there is provided a molding method of the epoxy resin molded article wherein the epoxy resin composition is a mixture of an epoxy resin, a curing agent, a curing accelerator, and an inorganic filler.

According to the present invention, there is provided a molding method of the epoxy resin molded article wherein the epoxy resin is used alone or in combination with orthocresol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, and hydroquinone type epoxy resin.

In addition, according to the present invention, an epoxy resin, a phenol resin, a curing accelerator, and an inorganic filler are included as essential components,

(1) The gel time at 80 ° C. is 1,500 seconds or more, and

(2) The change in melt viscosity at 100 ° C (maximum of melt viscosity / minimum of melt viscosity) is 10 or less in 18 minutes from the start of viscosity measurement,

(3) The change in melt viscosity at 110 ° C. (maximum of melt viscosity / minimum melt viscosity) is 7 or less in 10 minutes from the start of viscosity measurement,

(4) The change in melt viscosity (maximum melt viscosity / melt viscosity) at 180 ° C. reaches 10 or more within 60 seconds from the start of viscosity measurement.

An injection moldable epoxy resin composition is provided.

Moreover, according to this invention, the said injection moldable epoxy resin composition whose gel time in 100 degreeC is 1,000 second or more is provided.

In addition, according to the present invention, an epoxy resin, a phenol resin, a curing accelerator, and an inorganic filler are included as essential components,

(1) The gel time at 80 ° C. is 1,500 seconds or more:

(2) the gel time at 100 ° C. is 1,000 seconds or more, and

(3) the activation energy of the reaction is 12,000cal / mol or more

An injection moldable epoxy resin composition is provided.

According to the present invention, there is provided the epoxy resin composition wherein the epoxy resin is used alone or in combination with orthocresol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, and hydroquinone type epoxy resin.

Molding method of epoxy resin composition

An important technical feature of the first invention of the present invention is the injection molding of a specific epoxy resin composition using a mini sprue mold set at a specific temperature state, whereby the resin present in the manifold portion does not cure. In addition, since it always maintains the flow state, injection molding is possible continuously, and the cured product other than the molded article, that is, the discarded portion, consists only of the mini sprue portion and the mini runner portion, which shortens the molding cycle and at the same time produces the product. This characteristic of improvement improves the unique effect which cannot be achieved by conventional injection molding of a thermosetting resin.

Mini sprue mold

The injection molding die used in the present invention is composed of a manifold portion 10, a mini sprue portion 20 and an ejector plate portion 30, as shown in the main part sectional view of FIG. The manifold part 10 becomes the sprue 11 and the runner 12, and the temperature of this part is set to the temperature which epoxy resin melt | dissolves and hardening is not accelerated | stimulated, for example, 70-100 degreeC. This temperature condition is normally maintained by heating with a heater while cooling with cooling water.

That is, in the present invention, it is important that the manifold portion is a region that is responsible for melting the epoxy resin and does not participate in the curing of the epoxy resin.

Therefore, since the epoxy resins constituting the sprue 11 and the runner 12 of the manifold portion can always remain in a flow state without curing, they are not taken out together with the molded article, and after taking out the molded article and the mini sprue portion, Subsequently, it can be provided to injection molding continuously.

The mini sprue portion 20 is a region for curing the epoxy resin, and is composed of a mini sprue 21, a molded article extruded portion 22, a mini runner portion 23, and a gate portion 24. When taking out, only the mini spruce simultaneously taken out as hardened | cured material is discarded.

 The temperature of the mini spur portion at the time of shaping | molding is normally 160-200 degreeC, and it sets to the temperature about 90-130 degreeC higher than the temperature of the said manifold part and a product part. The ejector plate part is an area for molding after the molding is pushed out of the mold by the ejector pin 31 and demolded. The temperature of this area is set to a temperature at which the epoxy resin is hardened and accelerated like the mini sprue part.

In the mini sprue mold shown in Figs. 2 and 3, it is important that the epoxy resin used in the present invention is not cured at the manifold portion but cured at the mini sprue portion.

In order to satisfy this demand, in the present invention, the mold temperature of the manifold portion is set to a temperature at which the epoxy resin melts and does not promote hardening, that is, a temperature 90 to 130 ° C lower than that of the mini sprue portion and the product portion.

It is important that the epoxy resin used in the present invention has latent curing properties in which the curing is not promoted in the manifold portion, but the curing is promoted in the minispur portion in the mini sprue mold shown in Figs. As such a composition, the following composition I. II. III is illustrated.

The epoxy resin composition used in the present invention satisfies the above requirements, which contributes to the shortening of the molding cycle because it only melts in the manifold and does not promote curing, and promotes curing in a short gel time in the mini sprue. .

Epoxy resin composition

The epoxy resin composition of the present invention is capable of injection molding containing an epoxy resin, a phenol resin, a curing accelerator, and an inorganic filler as essential components, and the following three compositions are preferably exemplified.

The first composition (composition I) has a gel time of at least 1,000 seconds, preferably a gel time of at least 1,000 seconds at 100 ° C, and an activation energy of the reaction of at least 12,000 cal / mol.

In the second composition (Composition II), the gel time at 80 ° C of the epoxy resin composition is 1,500 seconds or more, preferably the gel time at 100 ° C is 1,000 seconds or more, and the melting point at 100 ° C of the epoxy resin composition. The change in the figure is 10 or less at 18 minutes after the start of the viscosity measurement, at 10 ° C at 110 ° C, or at 10 ° C from the start of the viscosity measurement, and the change in melt viscosity at 180 ° C reaches 10 or more within 60 seconds from the start of the viscosity measurement. It is an epoxy resin composition.

The change in melt viscosity in the present invention means a value obtained by dividing the maximum melt viscosity by the minimum melt viscosity, that is, "maximum melt viscosity / minimum melt viscosity".

By setting the melt viscosity characteristic of the epoxy resin composition to the above specific range, it is excellent in thermal stability without curing in the cylinder, and can satisfy the quick curing in the mold.

The third composition (composition III) of the epoxy resin composition of the present invention has a gel time of at least 1,500 seconds at 80 ° C, a gel time of at least 1,000 seconds at 100 ° C, and an activation energy of the reaction of at least 12,000 cal / mol. Epoxy resin composition. The upper limit of these requirements is not specifically limited.

Of these epoxy resin compositions, compositions II and III are particularly preferred in the present invention.

In addition, activation energy of reaction of an epoxy resin composition means what is computed from the following Arrhenius' equation (1).

K: rate constant A: frequency constant E: activation energy of the reaction (cal / mol)

R: Gas constant T: Temperature (° K) G: When gel time (sec) of molding material is taken;

K = ^{Ae (-E / RT)}

LN K = LN (1 / G) = LN A-E / RT. (One)

E is calculated from the slope of the graph of LN (1 / G) and 1 / T.

When the gel time characteristic and the activation energy of reaction of an epoxy resin composition are the said specific thing, it does not harden in a cylinder, it is excellent in thermal stability and can satisfy | fill rapid hardenability in a metal mold | die.

Epoxy resins used in the epoxy resin compositions (compositions II, III, etc.) of the present invention include monomers and polymers having an epoxy group as long as the melt viscosity characteristics, the gel time characteristics, and the activation energy of the reaction are satisfied. Although all can be used, For example, an orthocresol type epoxy resin, a biphenyl type epoxy resin, a naphthalene type epoxy resin, a hydroquinone type epoxy resin individually or in combination is illustrated, but any other epoxy resin which satisfy | fills the said prescription | regulation besides this is illustrated. Gun can be used.

The epoxy resin composition used in the epoxy resin composition (compositions II, III, etc.) of the present invention is constituted by appropriately blending a phenol resin, a curing accelerator, and an inorganic filler with the curing agent in the epoxy resin. As the curing agent, those having a phenolic hydroxyl group and acid hydrazide can be used, and specific examples thereof include phenol novolak resin, dichloropentadiene type phenol resin, eicosan hydrazide, and the like, which are used alone or in combination. There is a number.

As a phenol novolak resin, the novolak-type phenol resin obtained by making formaldehyde react with phenols, such as phenol, cresol, and xylenol, using an acidic catalyst, and its modified resin, for example, epoxidized or butylated novolak-type phenol resin Among them, those having a hydroxyl equivalent weight of 100 to 150 and a softening point of 60 to 110 ° C are preferably used.

The curing agent is blended in an amount of 20 to 70 parts by weight, preferably 40 to 60 parts by weight, based on 100 parts by weight of epoxy resin, but the blending ratio is phenol novolac resin, for example, per epoxy group contained in epoxy resin. It corresponds to the ratio which becomes 0.5-2.0 pieces, Preferably it is about 1, phenolic hydroxyl group.

As the curing accelerator, those which promote the curing reaction of epoxy resins such as aromatic and alicyclic dimethylurea and dicyandiamide and the curing agent, and satisfy the thermal stability in the cylinder of the injection molding machine and the rapid curing in the mold part are used.

Specific examples thereof include DBU derivatives such as 1,8-diazacyclo (5,4,0) undecene-7phenol salt, phenol novolak salt and carbonate salt, imidazoles selected from 2-methylimidazole CNS and formula Ar And urea derivatives represented by -NH-CO-NR ₂ (Ar is a substituted or unsubstituted aryl group, R is an alkyl group which may be the same or different), and among these, obtaining an injectable epoxy resin composition having excellent physical properties In order to use the urea derivative represented by the formula Ar-NH-CO-NR ₂ (Ar is a substituted or unsubstituted aryl group, R is an alkyl group which may be the same or different).

In addition, by using the alkyl urea derivatives represented by the following formulas (1 to 6) as curing accelerators, the stability in the vicinity of 100 ° C is greatly improved, and as a result, the thermal stability in the injection molding machine cylinder is improved.

(Eq. 1)

(Wherein X ₁ and X ₂ are hydrogen, a halogen, an alkyl group, preferably a lower alkyl group having 1 to 5 carbon atoms, an alkoxy group, preferably a lower alkoxy group having 1 to 5 carbon atoms or a nitro group, and both are the same Or R may be the same or different, respectively, preferably an alkyl group, preferably an alkyl group having 1 to 10 carbon atoms, particularly preferably 1 to 5 carbon atoms).

Examples of such compounds include 3-phenyl-1,1-dimethylurea, 3- (p-chlorophenyl) -1,1-dimethylurea, 3- (3,4-dichlorophenyl) -1,1dimethylurea, 3- (o-methylphenyl) -1, 1-dimethylurea, 3- (p-methylphenyl) -1,1-dimethylurea, 3- (methoxyphenyl) -1,1-dimethylurea, 3- (nitrophenyl 1,1-dimethylurea, etc. are mentioned.

Formula (2)

(Wherein Y and Z are hydrogen, a halogen or an alkyl group, preferably a lower alkyl group having 1 to 5 carbon atoms, and both may be the same or different. Each of R is a lower alkyl group which may be the same or different.)

Examples of such a compound include 1,1'-phenylenebis- (3,3-dimethylurea), 1,1 '-(4-methyl-m-phenylene) -bis (3,3-dimethylurea), and the like. Can be mentioned.

Formula (3)

(Wherein each R is a lower alkyl group which may be the same or different)

Formula (4)

(Wherein P is an integer of 0 to 5 and each of R is an alkyl group which may be the same or different, preferably 1 to 10, and particularly preferably an alkyl group having 1 to 5 carbon atoms)

Formula (5)

or

Formula (6)

(Wherein each of R is an alkyl group which may be the same or different, preferably 1 to 10, particularly preferably an alkyl group having 1 to 5 carbon atoms)

As an alkyl group or an alkoxy group of X <_1> , X <_2> and R of said Formula (1-6), a methyl group, an ethyl group, a propyl group, and a butyl group, or the alkoxy group equivalent is preferable. As the compound corresponding to formula (5), dimethylamine adducts of 2,4-tolylene diisocyanate are exemplified. Among them, dimethylamine adducts greatly improve the stability in the vicinity of 100 ° C, and thus, in the injection molding of the present invention, It is preferably used because it realizes suitable curing characteristics. These hardening accelerators are mix | blended in the ratio of 3-20 weight part, Preferably it is 5-10 weight part with respect to 100 weight part of epoxy resins.

In addition, such as 2-methylimidazole and triphenylphosphine, which have been conventionally used in transfer molding, a curing accelerator, in which injection stability was not possible due to lack of thermal stability in a cylinder alone, and curing in a mold It can be used together to save time.

As inorganic fillers, talc, ferrite, graphite, silicon nitride, mica, calcium carbonate, clay, alumina, alumina silica, crushed silica, spherical silica, zinc oxide, carbon, aluminum hydroxide, asbestos fiber, glass fiber, carbon fiber, glass bis Although powder, fibrous, balloon-like things, such as a silas balloon and a silica balloon, are illustrated, Among these, crushed silica, spherical silica, and glass fiber are used alone or in combination.

The epoxy resin composition of the present invention may be formulated with a flame retardant such as brominated epoxy resin, anthmonium trioxide, a colorant such as a silane coupling agent, carbon black, or phthalocyanine, or a release agent such as natural or synthetic wax, or silicone oil. There is a number.

Example

Next, an Example demonstrates this invention. This Example shows the most suitable embodiment of this invention, and is not limited to this, unless it deviates from the summary of invention.

Examples 1-3 and Comparative Examples 1 and 2

Formulations in Examples 1 to 3 and Comparative Examples 1 and 2 and gel times at 80 ° C. and gel times at 100 ° C. for each composition. Measure the MAX / MIN value (hereinafter referred to as melt viscosity property at 100 ° C), melt viscosity property at 110 ° C, and melt viscosity property at 180 ° C from the start of viscosity measurement at 100 ° C to a certain time. It is shown in Table 1.

TABLE 1

In the present invention, the viscosity change and the gel time were measured by the following method.

Measuring instrument: Toyo Seiki Seisakusho Labopura Tosumiru 20R200

        Roller Mixer R-30

Measuring resin amount: 43 g

Rotor Rotation: 30rpm

Measurement temperature: 80 ℃, 100 ℃

Viscosity: The viscosity is read from the torque (kg · m) on the chart of FIG. 1.

Measurement start: The point B on the chart shown in FIG. 1 is referred to as measurement start.

Gel time is performed by reading gel time from the chart shown in FIG.

"First, draw a line between the area where the torque decreases (tangential ①), the area holding the minimum torque (tangent ②), and the highest torque point A (the waterline ③) after sample insertion. Next, the intersection of the tangent ① and the tangent ② Obtain the length to the repair ③ and make it gel time.

In the present invention, the melt viscosity characteristic at 100 ° C. is the maximum (MAX) value / minimum (MIN) value of the viscosity for 18 minutes from the viscosity measurement start (B point), and the melt viscosity characteristic at 110 ° C. is the viscosity measurement start ( The maximum (MAX) / minimum (MIN) value of the viscosity for 10 minutes from the point B) and the melt viscosity characteristic at 180 ° C. change the melt viscosity (MAX value / MIN value of the melt viscosity) from the start of the viscosity measurement. The number of seconds to reach the above is displayed.

The injection molding (continuous forming) of each composition was evaluated, and the type of molding method, molding conditions, molding cycle, waste weight, and product weight were all shown in Table 2.

In addition, the injection molding method was formed by contacting the tip of the mold sprue push section with the tip of the injection molding machine nozzle, and judged whether continuous molding was possible by injection or not by curing the nozzle tip.

TABLE 2

Examples 4-6 and Comparative Examples 3, 4

The formulation in Examples 4 to 6 and Comparative Examples 3 and 4 and the gel time at 80 ° C., the gel time at 100 ° C. and the activation energy (cal / mol) of the reaction were measured for each composition, and their injection molding properties were measured. The results are shown in Table 3 together with the type of molding method, molding conditions, molding cycle, waste weight, and product part weight.

Evaluation of continuity formation was performed according to whether the mold sprue push part tip and the nozzle tip part were continuously molded and the amount of cushion remaining at the nozzle tip after injection was stable and unfilled occurred.

In this example and the comparative example, the measurement of the gel time and the activation energy of the reaction was carried out by the above-described method.

TABLE 3

In addition, the cushion amount (mm) for evaluating continuity formation in Examples 4 to 6 was as in Table 4 below.

TABLE 4

Molding conditions in the Examples and Comparative Examples are shown in Table 5.

TABLE 5

Examples 7, 8 and Comparative Examples 5-8

Table 6 shows the formulations in Examples 7, 8 and Comparative Examples 5-8.

TABLE 6

Examples 7, 8 and Comparative Examples 5 and 6 were injection molding using a mini sprue mold, Comparative Example 7 was injection molding using a conventional mold, and Comparative Example 8 was by transfer molding.

The molding conditions of each example are shown in Tables 7 to 9 below.

Injection molding using mini sprue mold

TABLE 7

Injection molding using conventional mold

TABLE 8

Transfer Molding

TABLE 9

Table 10 shows the results of Examples 7, 8 and Comparative Examples 5-8.

TABLE 10

According to the present invention, by using an epoxy resin composition having specific physical properties as a material of a molding material and molding it into a mini sprue mold, the molding cycle can be shortened and continuous molding can be performed. An injection molding method of epoxy resin is provided which can be minimized.

As a result, the epoxy resin molded article, which has not been able to be continuously formed by injection molding, can be continuously molded in a short cycle, and the epoxy resin molded article having excellent physical properties can be provided with good production efficiency.

1 is a view for explaining the measurement of the viscosity in the present invention and a method for measuring the gel time.

Figure 2 is an overall side view of the mini sprue mold used in the present invention.

3 is a cross-sectional view of main parts of FIG. 2;

Explanation of symbols for the main parts of the drawings

   10: manifold

   11: sprue

   12: runner

   20: Mini Spurubu

   21: mini spruce

   22: product

   23: mini runner

   24: gate portion

   30: ejector plate portion

   31: ejector pin

Claims (6)

Epoxy resin, phenol resin, curing accelerator and inorganic filler are included as essential components, (1) The gel time at 80 ° C. is 1,500 seconds or more, and (2) The change in melt viscosity at 100 ° C (maximum of melt viscosity / minimum of melt viscosity) is 10 or less in 18 minutes from the start of viscosity measurement, (3) The change in melt viscosity at 110 ° C. (maximum of melt viscosity / minimum melt viscosity) is 7 or less in 10 minutes from the start of viscosity measurement, (4) The change in melt viscosity at 180 ° C (maximum of melt viscosity / minimum of melt viscosity) reaches 10 or more within 60 seconds from the start of viscosity measurement Injection moldable epoxy resin composition, characterized in that. The method of claim 1, An injection moldable epoxy resin composition having a gel time of at least 1,000 seconds at 100 ° C. Epoxy resin, phenol resin, curing accelerator and inorganic filler are included as essential components, (1) The gel time at 80 ° C. is 1,500 seconds or more: (2) the gel time at 100 ° C. is 1,000 seconds or more, and (3) the activation energy of the reaction is 12,000cal / mol or more An injection moldable epoxy resin composition, characterized in that. The method according to claim 1 or 3, Epoxy resin composition of the epoxy resin alone or in combination of orthocresol type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, hydroquinone type epoxy resin. The epoxy according to claim 1 or 3, comprising a manifold portion, a mini sprue portion, and an ejector plate portion, wherein the mold temperature of the manifold portion is set to a temperature at which the epoxy resin composition is melted and hardening is not promoted. Injection molding of an epoxy resin molded article, characterized in that injection molding using a resin composition. The method of claim 5, An injection molding method of an epoxy resin molded article in which the mold temperature of the manifold portion is set to 90 to 130 ° C lower than the mold temperature of the mini sprue portion and the product portion.

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