JP3144866B2 - Melamine resin molding material for injection molding - 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 molding material for injection molding capable of forming a molded article, wherein pulp and a higher fatty acid ester are contained in specific amounts to a melamine / formaldehyde-based resin. The present invention relates to a melamine resin molding material for use.

[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 above 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 molded article obtained has reduced weather resistance, has a problem of "formalin elution" when used as tableware, has a difficulty in coloring only in a dark color system, and has a reduced flexibility in coloring. It was difficult to avoid the problem that the electrical characteristics deteriorated.

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 melamine-based resins.
No. 8261 discloses `` (1) 100 parts by weight of an amino resin, (b) 25 to 60 parts by weight of a filler, (c) 0.5 g of polyethylene glycol having a molecular weight of 6000 to 20,000 and a maximum particle size of 74 μm or less. ~ 3 parts by weight, (d) and an injection molding material of amino resin characterized by comprising a release agent, a curing agent, a coloring agent and the like. "

[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. Research to develop melamine-based resin molding materials for injection molding that can mold melamine-based resin molded products that have appearance and have excellent physical properties required for various molded products such as crack resistance and insert resistance. As a result, the present inventors have found that the intended purpose can be completely solved by adding specific amounts of pulp and glycerol monolaurate to the melamine / formaldehyde resin, and completed the present invention.

[0011]

According to the present invention, there are provided (B) 20 to 60 parts by weight of pulp and (C) glycerol monolauree per 100 parts by weight of a melamine / formaldehyde resin.
It is an object of the present invention to provide a melamine-based resin molding material for injection molding , comprising 0.1 to 3 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 melamine co-condensation resin in the melamine-based blended resin is preferably about 0.4 or less from the same viewpoint.

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 speed of the obtained molding material 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 molding material for injection molding of the present invention comprises the component (B) together with the melamine resin of the component (A).
Pulp.

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 material tends to deteriorate, which is not preferable. Is unfavorable because the mechanical strength such as insert resistance and crack resistance of the obtained molded article tends to decrease.

The melamine resin molding material for injection molding of the present invention contains glycerol monolaurate as component (C) together with the melamine resin as component (A) and pulp as component (B). It is made.

Glycerol monolauray of the above component (C)
The amount bet is 0.1 to 100 parts by weight of a melamine resin
It is 3 parts by weight, preferably 0.1 to 2 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 molding material for injection molding of the present invention can 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.

Furthermore, the melamine resin molding material for injection molding of the present invention generally contains a curing catalyst and a metal soap.

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

The mixing amounts of the curing catalyst and the metal soap 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-based resin molding material for injection molding of the present invention may contain other appropriate additives depending on the desired purpose as long as 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 mol 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 molding material for injection molding according to the present invention is characterized in that pulp is added to an aqueous solution of the melamine resin having a resin solid content of about 40 to 60% by weight, and 25 to 50 parts by weight based on 100 parts by weight of the melamine resin. added in an amount of parts by weight, further, glyceraldehyde
Serol monolaurate is blended in an amount of 0.1 to 3 parts by weight with respect to 100 parts by weight of the melamine resin, kneaded, and dried at a temperature of, for example, about 70 to 100 ° C. A popcorn-like pre-dried product of about 0.5 cm is crushed, if necessary, together with the other additives to form a powdered melamine resin mixture, and then the mixture is subjected to, for example, an extruder or a heating roll machine. It is preferable to manufacture the preformed product obtained by heating and kneading by re-milling 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 or a co-kneader can be used. Examples of the drying means include hot air drying, band dryer drying and fluidized drying.

The method for producing the powdered melamine resin mixture is not limited to the above-mentioned method. For example, glycerol monolaurate is not added or only a part thereof is added during the production of a popcorn-like pre-dried product. The rest or all of the material can be added during the pulverization of the product.

As a method for producing the powdery melamine resin mixture, the aqueous solution of the melamine resin produced by the above method is dried by a known method such as drying under reduced pressure and spray drying. In addition, powder pulp, the glycerol monolaurate and the 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 Loedige mixer, a ribbon A so-called dry method in which a conventional mixer such as a blender or a planetary mixer is used to uniformly mix the mixture can be used.

Further, 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. Solid melamine resin, powdered pulp, glycerol monolaurate and a method of pulverizing and mixing the various additives used as needed by the pulverizing means, and powdering the components by means such as pre-crushing respectively. After that, a method of mixing using the above-described mixer can be exemplified.

Among these methods, the injection molding characteristics (cylinder stability, etc.) of the obtained molding material, and the appearance (spots, color unevenness, etc.) and physical properties (crack resistance, insert resistance, etc.) of the obtained molded product. From the viewpoint of good balance, the above-mentioned wet / dry eclectic method is preferable. Among them, the proportion of the popcorn-like pre-dried product in the total molding material is 10 to 70% by weight, particularly 20 to 50% by weight. preferable.

The melamine-based resin molding material for injection molding of the present invention is preferably prepared by heating and kneading the melamine-based resin mixture obtained as described above with an extruder, a heating roll machine, or the like, and obtaining a preformed product. 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 melamine-based resin molding material for injection molding of the present invention thus obtained has a particle size of preferably from the viewpoint of, for example, excellent meterability of the molding composition during molding.
75% by weight or more, and more preferably 80% by weight or more of those which pass 10 mesh sieve and do not pass 100 mesh sieve with JIS sieve. The heating and kneading conditions are 80 to 120 ° C and 10 to 30.
It is good because it exhibits excellent performance as a molding material that can be obtained in seconds.

[0048]

EXAMPLES Hereinafter, several embodiments of the present invention will be described in more detail with reference to Examples along with Comparative 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 dust loss prevention suitability is determined.

(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.

[0052]

(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: 100t 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) Disc flow characteristic test Using a disc-type test mold described in JIS K-6911, section 5.3.2, 5 g of a sample was kept at a mold temperature of 150 + -3 ° C., substantially at the center of the mold. Use a metal cylinder with an inner diameter of about 50 mm and a height of about 10 mm so that the sample is conical, and apply a load of 2000 kgf within 15 seconds.
And press molding for 2 minutes.

The major axis and the minor axis of the glossy portion of the molded disk are measured to 1 mm using 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 mmφ 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 rear Injection pressure: 900 kg / cm ² Molding time: 60 Second

[Evaluation Criteria] ◎ ・ ・ ・ ・ ・ ・ No change in mold surface condition ○ ・ ・ ・ ・ ・ ・ Very little bleed-out trace 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 item (5) was used at a mold temperature of 160 ° C and 165 ° 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 fixed side, 170 ° C. on movable side Cylinder temperature: 95 ° C. at front part, 70 ° C. at rear part 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.

[0066]

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

Each of ten test pieces was weighed with a hot air circulating drier 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 is 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 2 500 g of pulp (melamine resin) was added to 3000 g of the aqueous melamine resin solution (solid content: about 50% by weight) obtained in Reference Example 1.
After adding about 33 parts by weight to 100 parts by weight) and kneading with a kneader, the kneaded product 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, and 13.5 g of glycerol monolaurate (GO) as a higher fatty acid ester
(0.67% by weight) diluted with methanol, hemihydrate gypsum 160g (8.0% by weight), phthalic anhydride 0.8g (0.04% by weight)
Wt.) And 20 g of zinc stearate (1.0 wt.%), 7.9 g of titanium oxide (0.4 wt.%) As an inorganic pigment, and 0.2 g of quinacridone red as an organic pigment.
(0.01% by weight) and pulverized by a pot mill for 8 hours to obtain a powder of a melamine resin mixture for a red molded product.

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 pulverizing this preform, it was pulverized using an impact type pulverizer having a screen diameter of 5 mm to obtain a melamine resin molding material for injection molding.

Table 2 shows the composition of the obtained molding material, and Table 3 shows various properties of the molding material and various physical properties of the obtained molded article.

Comparative Example 1 In Example 1, glycerol monolaurate was replaced with PEG8
A melamine resin molding material for injection molding was obtained in the same manner as in Example 1 except that 000 was used.

The composition of the obtained molding material is shown in Table 2, and various properties of the molding material and various physical properties of the obtained molded product are shown in Table 3.

[0081]

[Table 2]

[0082]

[Table 3]

[0083]

The melamine resin molding material for injection molding according to the present invention is characterized in that the melamine / formaldehyde resin (A) contains specific amounts of pulp (B) and higher fatty acid ester (C), respectively. It is characterized by having a good balance of improved properties as a molding material for injection molding various melamine-based resin molded products.

If the blending amount of the higher fatty acid ester (C) is too small, the stability of the cylinder becomes poor, and if it is too large, the bleed-out prevention and the color unevenness prevention become poor. When polyethylene glycol is used instead of the higher fatty acid ester, the bleed-out prevention property and the color unevenness prevention property become poor, and the surface gloss is slightly lowered.

Further, the melamine resin molding material for injection molding of the present invention is obtained by a method in which a wet method and a dry method are compromised, that is, a popcorn-like pre-dried material obtained by a wet method,
Powder or solid melamine resin, powder pulp, higher fatty acid ester and inorganic filler, pigment used as required,
Various additives such as a curing catalyst, for example, after each previously powdered by means such as crushing, and then mixed using a mixer, then extruder, heated and kneaded with a heating roll machine,
It is preferable to manufacture the obtained preform by a method such as re-grinding.

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

If the proportion of the above pre-dried material is small, the color unevenness prevention tends to be slightly lowered, and if it is too large, crack resistance and 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-61-203159 (JP, A) JP-A-59-189162 (JP, A) JP-A-59-199750 (JP, A) JP-A-56-41246 (JP, A) JP-A-62-22848 (JP, A) JP-A-1-101359 (JP, A) JP-A-1-115595 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 61/00-61/34

Claims (1)

(57) [Claims] 1. A melamine / formaldehyde resin
For 100 parts by weight, (B) pulp 20 to 60 parts by weight, and
(C) A melamine-based resin molding material for injection molding, comprising 0.1 to 3 parts by weight of glycerol monolaurate .