JP3144862B2 - Melamine resin injection molding composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention has an excellent cylinder stability at the time of injection molding, has excellent appearance without blur and color unevenness, and has excellent molded article properties such as excellent crack resistance and insert resistance. More particularly, the present invention relates to a melamine-based resin injection molding composition capable of forming a molded article, wherein the melamine-based resin comprises specific amounts of pulp and a higher fatty acid amide with respect to a melamine / formaldehyde-based resin. The present invention relates to a composition for resin injection molding.

[0002]

2. Description of the Related Art Conventionally, injection molding has been widely used as a molding method for molding materials such as unsaturated polyester, phenolic resin and urea resin among thermosetting resin molding materials. As for the molding material of (1), compression molding is still mainly used, and molding materials that can be transfer-molded are also on the market, but those that can be injection-molded are not necessarily general.

[0003] This is because the conventional melamine-based resin molding material has insufficient cylinder stability at the time of injection molding as compared with other thermosetting resin molding materials. It is considered that the temperature difference from the temperature is small and the fluidization time, that is, the time from the start of the flow to the start of the curing is extremely short.

Several methods are known for making such a melamine resin molding material injection-moldable.

[0005] One method is to co-condense urea or phenol with melamine or blend urea resin or phenol resin with melamine resin in order to lower the fluidization temperature of the resin and extend the fluidization time. In order to achieve the intended purpose, urea or phenol is co-condensed with about 1 mol of urea or phenol per 1 mol of melamine, or melamine resin is plasticized. It is necessary to blend, for example, about 20 parts by weight of a urea resin or a phenol resin with respect to 100 parts by weight of the resin.

[0006] For this reason, the obtained molded article has reduced heat resistance and weather resistance, has a problem of "formalin elution" when used as tableware, and is hardly colored only in a dark color system, so that the flexibility of coloring is reduced. And the problem of poor electrical characteristics was inevitable.

A method has also been proposed in which a thermoplastic resin such as an acrylic resin or a vinyl chloride resin is blended with a melamine resin to externally plasticize the melamine resin. This tendency was remarkable in colored molded articles and dark colored molded articles.

[0008] It is also known to incorporate various fluidity modifiers into a melamine-based resin.
No. 61 discloses, `` (1) (a) 100 parts by weight of amino resin, (b) 25 to 60 parts by weight of filler, (c) the maximum particle system with a molecular weight of 6000 to 20,000
An amino resin injection molding material characterized by comprising 0.5 to 3 parts by weight of polyethylene glycol of 74 μm or less, (d) and a releasing agent, a curing agent, a coloring agent and the like. "Has been proposed.

[0009] However, the molding material proposed above also tends to cause color unevenness similarly to the above, and this tendency is particularly remarkable in a colored molded product or a dark-colored molded product. There is a problem that gloss unevenness is likely to be caused, and it is not always sufficient.

[0010]

SUMMARY OF THE INVENTION As described above, the present inventors have improved the cylinder stability at the time of injection molding, which was insufficient with the conventional melamine-based resin molding material, and have provided an excellent molding without blurring and color unevenness. To develop a melamine-based resin injection molding composition that can mold melamine-based resin molded products that have the appearance and also have the excellent physical properties required for various molded products such as crack resistance and insert resistance. According to the present invention, it has been found that the intended purpose can be completely solved by adding specific amounts of pulp and a higher fatty acid amide such as erucamide to melamine / formaldehyde resin, respectively. Was completed.

[0011]

According to the present invention, there are provided (A) 20 to 60 parts by weight of pulp and (C) carbon number excluding oleamide with respect to 100 parts by weight of a melamine / formaldehyde resin.
Unsaturated fatty acid amide having one 18 to 22 double bond
An object of the present invention is to provide a melamine resin injection molding composition characterized by containing 0.1 to 4 parts by weight.

Hereinafter, the present invention will be described in detail.

The melamine / component (A) used in the present invention
As a formaldehyde resin (hereinafter sometimes abbreviated as a melamine resin), the weather resistance of the obtained molded article,
Melamine / formaldehyde resin (hereinafter abbreviated as melamine resin) obtained by reacting melamine with formaldehyde from the viewpoints of excellent colorability and electrical properties, and especially the problem of "formalin elution" when the molded article is tableware. May be used).

As the melamine resin of the component (A), a part of the melamine is replaced by a melamine co-condensation component capable of co-condensing with the melamine and formaldehyde as long as the above-mentioned properties of the obtained molded article are not lost. A melamine / formaldehyde-based co-condensation resin (hereinafter sometimes abbreviated as a melamine co-condensation resin) obtained as described above can also be used.

Examples of the melamine co-condensation component include ureas such as urea, thiourea and ethylene urea; guanamines such as benzoguanamine, acetoguanamine, formguanamine, phenylacetoguanamine and CTU guanamine; and guanidine; Dicyandiamide,
Other amino compounds such as p-toluenesulfonamide; phenols such as phenol, cresol, xylenol, ethylphenol, butylphenol, and bisphenol A; other melamine cocondensation compounds such as xylene and saccharose; The components may be used in combination.

The substitution ratio of the melamine co-condensation component is about 0.2 or less in terms of molar ratio with respect to melamine from the viewpoint of the surface hardness, heat resistance, stain resistance and the like of the molded article as well as the above-mentioned molded article properties. It is preferred that the weight ratio is less than about 0.2, especially the molar ratio is about 0.1 or less and the weight ratio is about 0.1 or less.

Further, as the melamine resin of the component (A), the melamine resin and / or melamine co-condensation resin may be used as long as the characteristics of the molded article can be maintained.
A melamine / formaldehyde-based blended resin (hereinafter sometimes abbreviated as a melamine-based blended resin) obtained by blending a blending resin component made of a thermosetting or thermoplastic resin other than these can also be used.

As the blend resin component, for example,
Thermosetting resins such as urea resin, guanamine resin, phenolic resin (novolak type, resol type), xylene resin, epoxy resin, alkyd resin, unsaturated polyester resin; vinyl chloride resin, vinyl acetate resin, acrylic And a thermoplastic resin such as a polyethylene terephthalate resin.

The weight ratio of the blending resin component to the melamine resin and / or the melamine co-condensation resin in the melamine-based blend resin is less than about 0.2 from the same viewpoint as described above.
In particular, it is preferably about 0.1 or less.

The melamine resin or melamine co-condensation resin is used in an amount of 1 mol based on the total amount of melamine or melamine and the melamine co-condensation component used as required.
It is preferable to react about 1 to 3 mol of formaldehyde, and it is particularly preferable to react about 1.4 to about 2.5 mol. When the molar ratio is equal to or less than the upper limit, the molded article does not become brittle and excellent properties such as crack resistance are preferably maintained. On the other hand, when the molar ratio is equal to or greater than the lower limit, It is preferable because the curing rate of the obtained molding composition does not decrease and the obtained molded product has a good "soldering" condition.

The above-mentioned formaldehyde includes a compound such as paraformaldehyde which substantially acts as formaldehyde when reacting with the above-mentioned melamine and the melamine co-condensation component.

Part of the formaldehyde reacts with an aldehyde component other than formaldehyde, for example, an aliphatic aldehyde such as acetaldehyde; an aromatic aldehyde such as benzaldehyde; furfural; and the melamine and the melamine co-condensation component. It can be replaced by the resulting aldehyde compound.

The amount of the aldehyde component other than formaldehyde is about 1 mole per 1 mole of formaldehyde from the viewpoint of the reactivity with melamine and the melamine co-condensation component and the curing rate of the obtained melamine resin and melamine co-condensation resin. It is preferably 0.5 mol or less.

The melamine resin injection molding composition of the present invention contains the pulp of the component (B) together with the melamine resin of the component (A).

The above-mentioned pulp generally refers to a chain polymer mainly composed of α-cellulose derived from a cellulose raw material, which is a raw material for paper, chemical fiber, cellulosic plastic and the like. Fibers made from cellulose and raw materials obtained by treating wood and linter are used.

The amount of the pulp is 10
It is 20 to 60 parts by weight, preferably 25 to 50 parts by weight, based on 0 parts by weight. If the compounding amount is too large beyond the upper limit, molding suitability such as flow characteristics and minimum molding pressure characteristics of the obtained molding composition tends to deteriorate, which is not preferable. If it is too long, mechanical strength such as insert resistance and crack resistance of the obtained molded article tends to decrease, which is not preferable.

The composition for injection molding of a melamine resin according to the present invention comprises, together with the melamine resin of the component (A) and the pulp of the component (B), a higher fatty acid amide of the component (C). It is.

As the above higher fatty acid amide, oleic
Has one double bond of 18 to 22 carbon atoms excluding acid amide
It is preferable to use an appropriately selected unsaturated fatty acid amide .

[0029] Such unsaturated fatty acid amides include:
For example, erucamide, elaidic amide, plush
It can be exemplified gin acid amide.

Of these higher fatty acid amides, those having a good dispersibility and a melting point of about 110 ° C. or less, particularly preferably about 100 ° C. or less, are preferably used in the production of the molding composition. As amide, elaidin
Examples thereof include acid amide, erucamide, and brassic acid amide .

The amount of the higher fatty acid amide used as the component (C) is 0.1 to 4 parts by weight based on 100 parts by weight of the melamine resin.
Preferably it is 0.2 to 3 parts by weight. If the amount used is too large above the upper limit, the resulting molded article tends to be unsatisfactory in color unevenness and bleed-out prevention, and on the other hand, if it is too small below the lower limit. In addition, cylinder stability during injection molding tends to be insufficient, which is not preferable.

The melamine resin injection molding composition of the present invention may contain an inorganic filler, if necessary.

Examples of such inorganic fillers include, for example, calcium carbonate, barium sulfate, talc, clay, silica, gypsum, glass powder and the like.
The amount of the inorganic filler used is preferably 0 to 20 parts by weight, and more preferably 2 to 15 parts by weight, based on 100 parts by weight of the melamine resin. When the amount is less than or equal to the upper limit, the molded article can be colored freely, and when it is 2 parts by weight or more, the "soldering" of the molded article becomes smooth and the insert resistance is also improved. preferable.

Further, the melamine resin injection molding composition of the present invention generally contains a curing catalyst and a metal soap.

As the curing catalyst, for example, phthalic anhydride, p-toluenesulfonic acid, p-toluenesulfonic acid triethanolamine salt, 2-aminoethylsulfonic acid, dimethylanilinesulfonic acid hydrochloride, melamine oxalate, ammonium chloride, phosphoric acid Ammonium, dimethyl oxalate, dibenzyl oxalate, dimethyl phthalate, trimethyl phosphate, acetamide, oxamide, benzoyl peroxide, and the like; examples of metal soaps include zinc stearate, zinc myristate, aluminum stearate, and calcium stearate. be able to.

The amounts of the curing catalysts and metal soaps are as follows:
Generally, 0 parts by weight for 100 parts by weight of the melamine resin.
The amount is preferably 2 to 2 parts by weight and 0 to 3 parts by weight, more preferably 0.01 to 1 part by weight and 0.1 to 2 parts by weight.

Further, the melamine resin injection molding composition of the present invention may contain other appropriate additives depending on the desired purpose, to the extent that the performance of the composition is not impaired.

These additives are, for example, organic or inorganic fibrous fillers other than pulp such as rock wool, glass fiber, synthetic fiber, etc .; for example, titanium oxide, zinc oxide, zinc sulfide, red iron oxide, dark blue, iron black, ultramarine Inorganic or organic pigments such as carbon black, lithopone, titanium yellow, cobalt blue, Hansa yellow, benzidine yellow, lake red, aniline black, dioxazine violet, quinacridone red, quinacridone violet, naphthol yellow, phthalocyanine blue, phthalocyanine green; For example, plasticizers such as dioctyl phthalate and dibutyl phthalate can be exemplified.

The melamine resin used in the present invention is, for example, a formaldehyde solution having a concentration of 37% and / or paraformaldehyde in an amount of about 1 to 2.5 per mole of so-called melamine crystal powder.
The reaction is carried out at a pH of about 7 to 9 in an aqueous medium at a reaction molar ratio of about mol, so that, for example, a resin concentration of about 40 to 60
It can be obtained as a melamine resin aqueous solution of about weight%.

The melamine resin injection molding material of the present invention is prepared by adding pulp to an aqueous solution of the melamine resin having a resin solid content of about 40 to 60% by weight, and adding 25 to 50 parts by weight to 100 parts by weight of the melamine resin. In addition, for example, a higher fatty acid amide such as erucamide is blended in an amount of 0.1 to 4 parts by weight with respect to 100 parts by weight of the melamine resin, and kneaded, for example, at about 70 to 100 ° C. Dried at a temperature of about 3 to 0.5 cm, for example, into a pre-dried popcorn having a diameter of about 3 to 0.5 cm, and, if necessary, pulverizing with the other additives to obtain a powdered melamine resin mixture. Then, the mixture is preferably produced by, for example, remilling a preform obtained by heating and kneading with an extruder, a heating roll machine or the like.

The pulverization of the popcorn-like pre-dried product can be performed by means such as an impact hammer mill, a ball mill, a vibration mill, and a tower mill. If desired, for example, after preliminarily pulverizing with an impact-type hammer mill, fine pulverizing may be performed by means of a ball mill, vibration mill, tower mill or the like. Also, commercially available pulp and melamine resin-containing molding powder can be used,
If desired, a commercially available molding powder can be further pulverized and used.

As the kneading means for forming the popcorn, a kneader, a co-kneader or the like can be used, and as the drying means, hot air drying, band dryer drying, fluidized drying and the like can be exemplified.

The method for producing the powdered melamine resin mixture is not limited to the above-mentioned method. For example, the higher fatty acid amide is not added or only a part thereof is added during the production of a popcorn-like pre-dried product. During the pulverization process, the remainder or the whole can be added.

As a method for producing the powdery melamine resin mixture, the melamine resin aqueous solution produced by the above method is dried by a known method such as drying under reduced pressure and spray drying to obtain a powdery melamine resin, if necessary. Powder pulp, the above-mentioned higher fatty acid amide and the above-mentioned various compounds used as required, for example, a V-type mixer, a super mixer, a Nauta mixer, a tumbler, an omni mixer, a Henschel mixer, a Ladyge mixer, a ribbon blender ,
A so-called dry method in which a conventional mixer such as a planetary mixer is used to uniformly mix the mixture can be used.

Furthermore, a method (wet / dry eclectic method) in which the above-mentioned wet method and the above-mentioned dry method are compromised can also be adopted. These methods include, for example, a popcorn-like pre-dried product, powder or powder by the wet method. A method of pulverizing and mixing the solid melamine resin, powder pulp, higher fatty acid amide and the various additives used as required by the pulverizing means, and pulverizing each of these components in advance by means such as crushing, and A method of mixing using a mixer can be exemplified.

Among these methods, the injection molding characteristics (such as cylinder stability) of the obtained molding composition, and
The wet / dry eclectic method is preferred from the viewpoint of a good balance between the appearance (blurring, unevenness of color, etc.) and physical properties (crack resistance, insert resistance, etc.) of the obtained molded article, and among them, all the molding compositions Popcorn-like pre-dried product accounts for 10-70% by weight, especially 20-50% by weight
It is preferred that

The melamine-based resin injection molding composition of the present invention is preferably prepared by heating and kneading the melamine-based resin mixture obtained as described above by using an extruder, a heating roll machine, or the like. Can be produced by re-grinding.

At this time, in the heating and kneading, an extruder which is appropriately selected without particular limitation can be used, and examples thereof include a single-screw extruder and a twin-screw extruder. The compression ratio and the temperature can be appropriately selected, and examples thereof include a compression ratio of 1 to 3 and a temperature condition of about 50 to 130 ° C. The extrusion end of the extruder may be of any type, such as an open type or a screen die type. The twin-screw extruder may be either a co-directional bi-axial type or a bi-directional bi-axial type. Further, the type of the heating roll machine can be appropriately selected.

The means for re-grinding the preformed product obtained by heating and kneading is not particularly limited, and any known pulverizing means can be used. If desired, a sieving means can be used in combination. Examples of the pulverizer used for such re-pulverization include an impact pulverizer, a hammer mill, an atomizer, a pin mill, a roll mill, and a pulperizer.

The composition for injection molding of the melamine resin of the present invention thus obtained has a particle size, preferably from JIS, in view of the excellent meterability of the molding composition at the time of molding.
It is preferable that the sieve that has passed the 10-mesh sieve and not passed through the 100-mesh sieve has a weight of 75% by weight or more, more preferably 80% by weight or more. The heating and kneading conditions are 80 to 120 ° C and 10 to 30.
Secondly, the composition exhibits excellent performance as a molding composition that can be obtained in seconds.

[0051]

EXAMPLES Hereinafter, several embodiments of the present invention will be described in more detail with reference to Examples, Comparative Examples and Reference Examples.

The various test methods used in the above Examples and Comparative Examples are as follows.

(1) Suitability for preventing dusting A 100 g sample is randomly collected according to JIS K-6911-1979. Gently pour it into a glass cylindrical container with an inner diameter of 50 mm and a height of 500 mm. At the bottom of this cylindrical container,
A No. 2 glass filter with a layer thickness of 5 mm is attached and has a shape that allows dry air to be blown in from the lower part of the container. Dry air is blown at a flow rate of 1000 ml / min for 1 minute from the lower part of the container containing the 100 g sample. By this operation, the weight loss rate (%) spilled out is determined, and the value is taken as the value of suitability for preventing dusting.

(2) Collapse resistance A sample of about 100 g was sampled, and a low tap shaking machine, 200φ
On a 80 mesh JIS standard sieve with a low tap rotation speed of 290 times /
Sieving for 10 minutes under the conditions of 156 strokes / minute and a total amplitude of 28 mm. Next, the weight of the sample on the sieve tray was measured, and thereafter, the sieving operation was continued for another 6 hours, the weight of the sample on the sieve tray was measured again, and the disintegration rate was calculated according to the following calculation formula. It shall be the value of collapse resistance.

[0055]

(Equation 1)

(3) Cylinder stability The weight of the molded product when the cavity is completely filled is
Using a spiral flow test mold weighing 45 g, the same sample is continuously molded in 50 shots under the following injection molding conditions. The weight of the spiral shaped product at the 50th shot is compared with the weight of the spiral shaped product at the 5th shot, and evaluated according to the following criteria.

[Injection molding conditions] Molding machine: 100 t injection molding machine Mold temperature: 170 ° C. on fixed side, 170 ° C. on movable side Cylinder temperature: 90 ° C. at front, 70 ° C. at back Injection pressure: 50 kg / cm ² (gauge pressure) Molding time: 60 seconds

[Evaluation Criteria] ・ ・ ・: Weight loss rate of 3% by weight or less ・ ・ ・: Weight loss rate of more than 3% by weight and 7% by weight or less △: Weight loss rate More than 7% by weight and less than 12% by weight X: Weight loss rate exceeds 12% by weight

(4) Disk flow characteristic test Using a disk-type test die described in JIS K-6911, section 5.3.2, a sample of 5 g was maintained at a die temperature of 150 + -3 ° C. at substantially the center of the die. Using a metal cylinder with an inner diameter of about 50 mm and a height of about 10 mm, put the sample into a conical shape and compress it within 15 seconds with a load of 2000 kgf and a pressing time of 2 minutes.

The major axis and the minor axis of the glossy portion of the molded disk are measured to 1 mm with a dimension measuring instrument, and the average value is calculated to obtain the elongation (mm) of the sample.

(5) Bleed-out Prevention A disk-shaped test piece having a diameter of 100 mm and a thickness of 3 mm is injection-molded under the following molding conditions. After removing the molded product, the degree of gloss in the movable mold cavity is visually observed and evaluated according to the following criteria.

[Injection molding conditions] Molding machine: 100t injection molding machine Mold temperature: 175 ° C on the fixed side, 175 ° C on the movable side Cylinder temperature: 95 ° C at the front, 70 ° C at the back Injection pressure: 900 kg / cm ² Molding time: 60 Second

[Evaluation Criteria] ◎ ・ ・ ・ ・ ・ ・ No change in mold surface condition ○ ・ ・ ・ ・ ・ ・ Very small trace of bleed-out on mold surface △ ・ ・ ・ ・ ・ ・ Bleed-out on mold surface There is a little trace X: Bleed out is large with no gloss on the mold surface

(6) Color non-uniformity preventing property The same test piece as in the above (5) was used at 160 ° C.
Injection molding is performed for each two sheets under the same molding conditions as in the above (5) except that the temperature is changed to ℃, 170 ℃, 175 ℃, 180 ℃ (both fixed side and movable side). The state of color unevenness of a total of 12 test pieces formed in this way is visually observed, and evaluated by the number of molded products without color unevenness.

(7) Surface Gloss of Molded Article The same test piece as in the above (5) is injection-molded under the same molding conditions. Gloss meter TG manufactured by Tokyo Denshoku Co., Ltd.
Measure using -P. Measured at an incident angle of 60 ° C, the refractive index is 1.
The gloss is measured with the specular gloss of the glass surface of 567 as 100%.

(8) Crack resistance of molded article An ashtray having an outer diameter of 120 mm, a height of 28 mm and a weight of 150 g is injection-molded under the following conditions.

[Injection molding conditions] Molding machine: 100t injection molding machine Mold temperature: 170 ° C on the fixed side, 170 ° C on the movable side Cylinder temperature: 95 ° C at the front, 70 ° C at the rear Injection pressure: 900 kg / cm ² Molding time: 60 Second

The ashtray thus formed is subjected to four cycles a day, with the next cycle as one cycle, and the number of cycles and the number of days until a crack is formed are determined.

[0069]

[Table 1]

The display of crack resistance is expressed as (days)-(cycles). For example, if the number is 2-3, the occurrence of cracks in the third cycle on the second day is indicated.

The crack resistance is preferably 3-1 or more, particularly preferably 4-1 or more.

(9) Insert resistance Under the following injection molding conditions, brass knurls (outer diameter 40
(mmφ, inner diameter 20mmφ, thickness 10mm) A ring of a resin molded product with the same thickness and an outer diameter of 52mmφ is integrally provided on the outer periphery of the test piece.

[Injection molding conditions] Molding machine: 100t injection molding machine Mold temperature: 175 ° C on the fixed side, 175 ° C on the movable side Cylinder temperature: front 90 ° C, rear 70 ° C Injection pressure: 900 kg / cm ² Molding time: 65 Second

Each of 10 test pieces was heated to 100
Heat at 25 ° C for 25 minutes, then cool with cold water for 5 minutes to make one cycle. The presence or absence of cracks is observed by this method, and evaluation is made based on the average value of the number of cycles in which cracks have occurred.

Reference Example 1 1260 g of melamine (manufactured by Yuka Melamine Co., Ltd .; Yuka Melamine)
(10 mol), 1380 g (17 mol) of 37% aqueous formalin solution and 900 g of water were placed in a flask equipped with a reflux condenser, and the F / M
The mixture was heated and reacted at 90 ° C. while stirring under the condition of 1.7. When the cloud point of the melamine resin solution reached 60 ° C., 0.8 g of sodium hydroxide was added and cooled to obtain an aqueous melamine resin solution.

The cloudiness point used as a guide at the end of the reaction refers to the temperature at which cloudiness occurs when 5 ml of a resin solution is collected, 45 ml of hot water at about 80 ° C. is added, stirred and cooled. .

Reference Example 2 To 3000 g of the melamine resin aqueous solution (solid content: about 50% by weight) obtained in Reference Example 1, 500 g of pulp (about 33 parts by weight based on 100 parts by weight of melamine resin) was added and kneaded with a kneader. Thereafter, the kneaded material was dried at 90 ° C. for 90 minutes with a hot air drier to obtain a popcorn-like pre-dried product. Then, about 2000 g of the pre-dried product was ground by a ball mill for 8 hours to obtain a powder of the pre-dried product.

REFERENCE EXAMPLE A The melamine resin aqueous solution (solid content: about 50% by weight) obtained in Reference Example 1 was dried at about 200 ° C. by a spray dryer to obtain a powdery melamine resin.

Example 1 The popcorn-like pre-dried powder 600 obtained in Reference Example 2
g (30.0% by weight based on the total amount of melamine resin mixture)
In addition, 900 g (44.9% by weight) of the powdered melamine resin of Reference Example A, 300 g (15.0% by weight) of powdered pulp, 13.5 g (0.67% by weight) of erucamide as a higher fatty acid amide , and 160 g of hemihydrate gypsum 8.0% by weight), 0.8 g of phthalic anhydride
0.04% by weight) and 20 g of zinc stearate (1.0% by weight), and 7.9 g of titanium oxide as an inorganic pigment
0.4% by weight) and phthalocyanine blue as an organic pigment.
After adding 20 g (0.01% by weight of the same) and pulverizing for 8 hours with a pot mill, a powder of a melamine-based resin mixture for a blue molded product was obtained.

Next, this resin mixture powder was heated and kneaded with a twin-screw extruder. The kneading extruder uses a screw with a shaft diameter of 55 mmφ, L / D = 20, and a compression ratio of 2.0, the cylinder temperature is set to 100 ° C.,
Under the conditions of a screw rotation speed of 100 rpm, a pre-molded product by heat extrusion and kneading was obtained. After coarsely crushing the preform, it was crushed using an impact crusher having a screen diameter of 5 mm to obtain a melamine resin injection molding composition.

COMPARATIVE EXAMPLE 1 Instead of erucamide in Example 1, the average
Polyethylene Chirenguriko of molecular weight 8000 - Le the (PEG8000)
A melamine resin injection molding was performed in the same manner as in Example 1 except that
A shaping composition was obtained.

Table 2 shows the composition of the obtained molding composition.
Table 3 shows various characteristics of the molding composition and various physical properties of the obtained molded product.

[0083]

[Table 2]

[0084]

[Table 3]

[0085]

The composition for injection molding of a melamine resin according to the present invention contains specific amounts of pulp (B) and higher fatty acid amide (C) with respect to the melamine / formaldehyde resin (A). It has a good balance of improved properties as a molding composition for injection molding various melamine-based resin molded products.

As is clear from the examples and comparative examples, if the amount of the pulp (B) used is too small, the color unevenness preventing property becomes unsatisfactory, and the cylinder stability, crack resistance and insert resistance also deteriorate. Will be enough. On the other hand, pulp (B)
If too much is used, cylinder stability will be poor.

If the amount of the higher fatty acid amide (C) is too small, the stability of the cylinder becomes poor. If the amount is too large, the bleed-out preventing property and the color unevenness preventing property become poor.

Further, the melamine resin injection molding composition of the present invention can be obtained by a method in which a wet method and a dry method are compromised, that is, a popcorn-like pre-dried product by a wet method,
Powder or solid melamine resin, powder pulp, higher fatty acid amide and optionally used inorganic fillers, pigments, various additives such as curing catalyst, for example, each after previously powdered by means such as crushing, and then a mixer. Mix using
Next, it is preferable to produce the preformed product by heating and kneading with an extruder, a heating roll machine or the like, and re-grinding the obtained preform.

When the above wet / dry eclectic method is used, the proportion of the popcorn-like pre-dried product in the whole molding composition should be 10 to 70% by weight, especially 20 to 50% by weight. Is preferred.

If the proportion of the above pre-dried material is small, the color unevenness preventing property tends to be slightly lowered, and if it is too large, the crack resistance and the insert resistance tend to be slightly insufficient. It is preferable that the ratio of the objects be in the above range.

Continuation of front page (56) References JP-A-2-227450 (JP, A) JP-A-52-111994 (JP, A) JP-A-61-203159 (JP, A) JP-A-2-97552 (JP, A) JP-A-59-189162 (JP, A) JP-A-59-199750 (JP, A) JP-A-5-230334 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) C08L 61/00-61/34

Claims (1)

(57) [Claims] (A) Melamine / formaldehyde resin 1
Against 00 parts by weight, (B) 20 to 60 parts by weight pulp, (C) I
One double bond having 18 to 22 carbon atoms excluding formic acid amide
A melamine-based resin injection molding composition comprising 0.1 to 4 parts by weight of an unsaturated fatty acid amide .