JP3144856B2 - Melamine resin molding granular composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved granular composition for molding melamine resin, which has a good balance of various improved properties mainly for compression molding of various melamine resin moldings.

[0002] In particular, the present invention does not adversely affect favorable properties of the melamine resin molded article such as heat resistance, hardness, high gloss, crack resistance, weather resistance, light resistance, stain resistance, and electrical properties. In addition, with improved automatic metering suitability of the molding composition in automatic compression molding and the like, for example,
It has excellent molding aptitude, such as appropriate flow characteristics that do not cause poor filling in the thread girder, etc., even in molded products with particularly large girths, such as hills, etc., and appropriate minimum molding pressure characteristics. In addition to having excellent moldability, which is difficult to achieve compatibility, and excellent bleedout prevention and releasability of the modifier with an excellent improving effect, furthermore, there is a problem such as the residual of grains on the surface of the molded article, which tends to be present in granular compositions. The present invention relates to a melamine-based resin molding granular composition which has no problem and can obtain a molded article having excellent appearance without color unevenness, even in a colored molded article in which color unevenness is particularly likely to occur.

More specifically, the present invention relates to (a) 100 parts by weight of a melamine / formaldehyde resin,
20 to 45 parts by weight of pulp and (c) monoglycidyl ester
The present invention relates to a melamine-based resin molding granular composition obtained by re-crushing a heat-kneaded preformed product of a resin mixture containing 0.1 to 3 parts by weight of a polyester.

[0004]

2. Description of the Related Art Conventionally, melamine resin molding materials are mainly formed by compression molding, but in recent years, automatic compression molding has often been performed in order to improve productivity. In the automatic compression molding, a molding material which is usually granulated is used for automatic measurement.

[0005] As a method of granulating the melamine resin molding material, there are a method in which the molding material powder is tabletted by heating without heating and then re-crushed, and a method in which the molding material powder is heated and kneaded to form a string. A method of re-crushing a preform formed by, for example, dispensing is known. However, in the former method, the obtained granules are easily disintegrated, and it is difficult to say that they are adequate in terms of aptitude for automatic weight reduction. On the other hand, in the latter method,
During heating and kneading, it is necessary to set the kneaded material to an appropriate viscosity at a considerably high temperature, and the temperature is further increased by frictional heat at the time of kneading, so that the condensation of the molding material may be excessively advanced. Particles often remain on the surface of the resulting molded article due to the presence of excessively hard particles and the like, and the surface gloss and "soldering" tend to deteriorate.

[0006] As a method for improving the granulation of such a melamine resin molding material and for improving the fluidity of the molding material at the time of molding, several proposals have been known for using a modifier. I have.

[0007] For example, Japanese Patent Publication No. 36-22883 discloses that "a polyoxyalkene such as polyethylene glycol having a molecular weight of 200 to 1500 or polypropylene glycol having a molecular weight of 150 to 500 is used in a urea and melamine resin precondensate for a molding material. A method for producing a modified urea and melamine resin molding material having a small shrinkage, especially a small shrinkage after molding, characterized by being added as a modifier of about 0.5 to 7%.

JP-A-50-53438 discloses that "a) an addition product of ethylene oxide or ethylene oxide / propylene oxide of 8 to 100 moles to 1 mole of an organic compound having 1 to 3 alcoholic hydroxyl groups, And b) a partial or neutral ester of a mono- to trivalent aliphatic, cycloaliphatic or aromatic carboxylic acid, wherein the alcohol component a) and / or the acid component
b) is characterized by containing an aliphatic hydrocarbon residue having 12 to 26 carbon atoms, with respect to the `` additives for the processing of molding compositions based on thermosetting condensation resins '' Proposed.

However, the molding material obtained according to these proposals tends to have excessive fluidity at the time of molding, which may cause poor filling at the thread jelly portion or the like of the molded product. However, inconveniences such as grain remaining on the surface of the molded product were liable to occur. Furthermore, it has been found that these molding materials do not sufficiently prevent the occurrence of color unevenness, and in particular, when molding a colored molded article or a dark colored molded article, remarkable color unevenness is observed.

The researchers of the present applicant have proposed melamine-based resin molding materials using various modifiers in order to achieve the above-mentioned object.

The modifiers in these proposals are as follows. (1) Polyethylene glycol and metal soap having an average molecular weight of 2000 to 10,000 (0.4 to 3 parts by weight and 0.4 to 4 parts by weight, respectively, with respect to 100 parts by weight of melamine resin) (JP-A-61-1)
No. 9765)

(2) Polyoxyethylene / polyoxypropylene block copolymer having an average molecular weight of more than 1000 and less than 3000 (0.4 to 3 parts by weight based on 100 parts by weight of melamine resin) (JP-A-61-203159)

(3) A polyoxyalkylene compound containing a polyoxyalkylene group and a group consisting of a saturated or unsaturated higher aliphatic compound in the same molecule (0.4 parts by weight per 100 parts by weight of melamine resin) -3 parts by weight)
-22848)

(4) Ester C (CH ₂ OH) _{2 + n} (CH ₂ R) _2-n of polyol compound of the following general formula and higher fatty acid (where R is hydrogen or C ₁ -C ₃ ) An alkyl group, n is an integer of 0, 1, or 2) (0.07 to 3 parts by weight based on 100 parts by weight of the melamine resin) (Japanese Patent Laid-Open No. 1-101359)

(5) Oleic acid ester of C ₁ -C ₁₀ linear or branched monoalcohol (0.07 to 3 parts by weight per 100 parts by weight of melamine resin) (JP-A-1-15952)

These proposed melamine-based resin molding materials were excellent ones which succeeded in having a considerable degree of moldability, bleed-out preventing property of the modifier and releasability. However, when molding a molded product having a particularly large thread jig such as a platen, a defective filling may occur in the thread jig or the like, or an achromatic molded product such as white or gray, or ivory. Even in the case of light-colored molded products with a small amount of chromatic pigments used in chromatic colors, etc., almost no color unevenness was observed. In the case of a molded article or the like, it has been found that color unevenness may occur depending on the shape of the molded article.

In the technical field of melamine resin molding materials, several compositions containing an epoxy compound are also known.

For example, JP-A-59-47253 discloses that
"(1) A melamine resin molding material characterized by using a melamine resin obtained by reacting melamine, polyethylene glycol diglycidyl ether and formaldehyde."
It is recommended to use polyethylene glycol diglycidyl ether to melamine in a weight ratio of 0.20 to 0.75.

Japanese Patent Application Laid-Open No. 1-319563 discloses "(1)
A melamine resin molding material comprising a modified melamine resin obtained by reacting formaldehyde with a reaction product of melamine and a glycidyl compound, wherein at least a fibrous filler is contained. And the molar ratio of the glycidyl compound to melamine is from 0.01 to 5.8 (the glycidyl compound as ethylene glycol diglycidyl ether is about 1.4 to 800 parts by weight based on 100 parts by weight of melamine). Recommended.

All of these proposals have been made mainly for the purpose of improving the impact resistance of the obtained molded article. A glycidyl compound such as polyethylene glycol diglycidyl ether is reacted with melamine or melamine and formaldehyde. The amount of the glycidyl compound used is usually considerably larger than that in the case of the present invention (in the former example, the glycidyl compound 1 was used per 100 parts by weight of melamine).
5 to 75 parts by weight, in the latter example 50 parts by weight of the glycidyl compound per 100 parts by weight of melamine).

On the other hand, the epoxy compound (c) in the present invention acts as a plasticizer during kneading of the resin mixture during the kneading of the resin mixture consisting of the above (a) to (c) by the kneading method. In addition to imparting good fluidity to the mixture, most of the compound (c) reacts with the melamine / formaldehyde resin (a) in the mixture during kneading. Occasionally, while exhibiting excellent automatic weighing suitability as described above, even when molding a molded product having a particularly large thread jelly portion such as a platen plate, excellent molding such as not causing a filling defect in the thread jelly portion or the like. Shows suitability, and does not cause inconvenience such as generation of grains on the surface of the molded article, which tends to occur in the case of a granular composition.Especially, even when obtaining a dark-colored molded article, color unevenness does not occur. Has an excellent appearance And made-to-heat, hardness, high gloss, crack resistance, weathering (light) resistance, stain resistance, and preferably superior melamine resin molding granular composition properties holding the like electrical properties.

As described above, the epoxy compound of the present invention and the glycidyl compound of the above two proposals have completely different functions and effects. In fact, as in these proposals, the glycidyl compound and melamine or melamine and It has been found that the effect of the present invention cannot be exerted by reacting with formaldehyde in advance.

Further, a proposal for a melamine resin molding composition containing an epoxy compound is disclosed in
One disclosed in Japanese Patent Application No. 60-40152 is known.

This proposal aims at improving the crack resistance of the obtained molded article and suppressing the rate of change of the post-dimension.
The present invention relates to "(1) an amino-based resin molding material containing an amino-based resin as a main resin component, characterized by containing an epoxy resin."
In this proposal, an epoxy resin is used in an amount of 1 to 20 parts by weight based on 20 to 40 parts by weight of an amino resin such as urea resin, melamine resin, guanamine resin and phenol-modified melamine resin.
It is recommended to include parts by weight.

Although this proposal does not preliminarily react an epoxy compound with melamine or melamine and formaldehyde, the use of an epoxy resin is too large.
When molding a colored molded article, the occurrence of color unevenness is inevitable.

[0026]

SUMMARY OF THE INVENTION The present inventors, while maintaining the excellent properties proposed by the researchers of the applicant of the present invention, have further improved these properties to obtain ordinary color unevenness such as colored molded articles. Research and development of an excellent granular composition for melamine-based resin molding that does not cause color unevenness even in molding of molded articles in which cracks easily occur.

As a result, for example, about 33 parts by weight of pulp and about 0.3 parts by weight of an epoxy compound such as s-butylphenol glycidyl ether per 100 parts by weight of the resin are added to an aqueous solution of a melamine / formaldehyde resin and kneaded in a kneader. The dried popcorn-like material is then pulverized in a ball mill together with a curing catalyst such as phthalic anhydride, a lubricant such as zinc stearate, and a pigment such as Watching Red Mn, and the resulting powdery resin mixture is twin-screw extruded. A granular composition prepared by heat kneading and extrusion using an extruder such as an extruder to prepare a preformed product, and then recrushing the preformed product,

Excellent automatic weighing ability, appropriate flow characteristics and appropriate flow properties that do not cause poor filling in the thread sliver of the molded product without adversely affecting the above-mentioned preferable properties of the melamine resin molding material. It has excellent molding aptitude shown by a minimum molding pressure characteristic, and also has a molding aptitude which is hard to be compatible, a bleed-out preventing property of a modifier and a mold releasability at the time of molding with an excellent improving effect. A melamine-based resin which has no problems such as residual grains on the surface of a molded product, which is apt to be present in a granular composition, and which has excellent appearance without color unevenness even in a colored molded product in which color unevenness is particularly likely to occur. The present inventors have found that the composition is a granular composition for molding, and have further studied to complete the present invention.

[0029]

According to the present invention, there are provided (a) 100 parts by weight of a melamine / formaldehyde resin,
(B) 20 to 45 parts by weight of pulp and (c) monoglyci
An object of the present invention is to provide a granular composition for molding a melamine-based resin, which is obtained by re-crushing a heat-kneaded preformed product of a resin mixture containing 0.1 to 3 parts by weight of a gall ether .

Hereinafter, the present invention will be described in detail. Melamine / formaldehyde resin of the above component (a) (hereinafter, referred to as
Melamine / formaldehyde resin obtained by reacting melamine and formaldehyde (hereinafter sometimes abbreviated as melamine resin); melamine, formaldehyde and co-condensable with these A melamine / formaldehyde-based co-condensation resin obtained by reacting a melamine co-condensation component (hereinafter sometimes abbreviated as a melamine co-condensation resin);
A melamine / formaldehyde-based blended resin (hereinafter, abbreviated as a melamine-based blended resin) obtained by blending the melamine resin and / or the melamine co-condensation resin with a blending resin component made of a thermosetting or thermoplastic resin other than these. In some cases).

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, and the like. Other amino compounds such as paratoluenesulfonamide; phenols such as phenol, cresol, xylenol, ethylphenol, butylphenol, bisphenol A;
Other compounds for co-condensation of melamine such as xylene and saccharose; and the like, and these components may be used in combination.

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.

In the melamine co-condensation resin, the ratio of the melamine co-condensation component to melamine is from the viewpoint of surface hardness, light (weather) resistance, heat resistance, stain resistance and the like of the obtained molded article. The weight ratio of the blending resin component to the melamine resin and / or the melamine co-condensation resin in the melamine-based blended resin is preferably about 0.7 or less and about 1 or less in weight ratio. The following is preferred.

The above-mentioned melamine resin or melamine co-condensation resin is used in an amount of about 1 mol of formaldehyde with respect to 1 mol of melamine alone or a total of 1 mol of melamine and the melamine co-condensation component.
Preferably, the reaction is carried out in an amount of about 3 to 3 mol, and particularly preferably about 1.4 to 2.5 mol. When the above molar ratio exceeds the upper limit of the above range, the molded article tends to be brittle, properties such as crack resistance may decrease, and when the above molar ratio is less than the lower limit of the above range, The curing speed of the obtained melamine-based resin molding material tends to decrease, and the “soldering” state of the molded product may also deteriorate.

The above-mentioned formaldehyde is used in the reaction with the melamine and the melamine co-condensation component such as paraformaldehyde.
A name that encompasses compounds that substantially act as formaldehyde.

A part of the formaldehyde is reacted 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 the above-mentioned formaldehyde is about 1 mol per 1 mol 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.

Among such melamine resins, the resins used in the present invention include melamine resins, melamine-phenol co-condensation resins, melamine-urea co-condensation resins, and blend resins obtained by blending melamine resins with novolak phenol resins. A blend resin obtained by blending a urea / formaldehyde resin with a melamine resin is preferred, and a melamine resin is most preferred.

The resin mixture in the granular composition for molding a melamine resin of the present invention contains 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 mixing amount of the pulp is 10
20 to 45 parts by weight with respect to 0 parts by weight . If the compounding amount is too large beyond the upper limit, molding suitability such as the flow characteristics and the minimum molding pressure characteristics of the obtained granular composition for molding tends to deteriorate, which is not preferable. If the amount is too small, the mechanical strength such as bending strength and crack resistance of the obtained molded article tends to decrease, which is not preferable.

The resin mixture in the granular composition for molding a melamine resin of the present invention contains the epoxy compound of the component (c) together with the melamine resin of the component (a) and the pulp of the component (b). Things.

As the above-mentioned epoxy compound, for example,
Monoglycidyl ethers such as allyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, 2-methyloctyl glycidyl ether, phenol glycidyl ether, and s-butylphenol glycidyl ether can be exemplified .

[0044]

[0045]

[0046]

The amount of the epoxy compound of component (c) used is 0.1 to 3 parts by weight based on 100 parts by weight of the melamine resin.
Preferably 0.15 to 1.5 parts by weight, particularly preferably 0.2 to 0.7 parts
Parts by weight. If the amount is too large beyond the upper limit, the resulting molded article may be uneven in color, or the epoxy compound may bleed out, which is not preferable. Too much, the component (c)
The effect of addition of melamine resin is not recognized, frictional heat increases during heating and kneading during granulation, the degree of condensation of the melamine resin tends to increase, and the surface gloss and "soldering" of the molded article tend to deteriorate, which is not preferable.

Further, the granular composition for molding a melamine resin of the present invention can be used in such an amount that the performance of the composition is not impaired.
Other appropriate additives can be contained depending on the desired purpose.

Examples of such additives include, for example,
Organic or inorganic fillers such as rock wool, glass fiber, synthetic fiber, calcium carbonate, talc, clay, silica, etc .; for example, phthalic anhydride, p-toluenesulfonic acid, dimethyl oxalate, dibenzyl oxalate, dimethyl phthalate, benzoyl peroxide Curing catalysts such as p-toluenesulfonic acid triethanolamine salt, 2-aminoethylsulfonic acid, dimethylanilinesulfonic acid hydrochloride, melamine oxalate, ammonium chloride, ammonium phosphate, trimethyl phosphate, acetamide, oxamide;

For example, titanium oxide, zinc oxide, zinc sulfide, red iron, navy blue, barium sulfate, iron black, ultramarine, carbon black, lithopone, titanium yellow, cobalt blue, Hansa yellow, benzidine yellow, lake red, aniline black, Oxazine violet,
Inorganic or organic pigments such as quinacridone red, quinacridone violet, naphthol yellow, phthalocyanine blue, and phthalocyanine green;

For example, zinc stearate, zinc myristate, aluminum stearate, calcium stearate, butyl stearate, stearyl stearate,
Dioctyl phthalate, dibutyl phthalate, stearamide, ε-caprolactam, oleamide,
Lubricants or plasticizers such as linoleic acid amide, stearyl alcohol, polyoxyethylene stearate, glycerin, and polyethylene glycol monooleate;

The granular composition for molding a melamine resin of the present invention can be suitably prepared, for example, by the so-called wet method described below.

For example, with respect to 1 mol of so-called melamine crystal powder, for example, a formaldehyde aqueous solution having a concentration of 36% and / or paraformaldehyde in a form of a reaction molar ratio of about 1 to 2.5 mol of formaldehyde in an aqueous medium. Reacting at a pH of about 7 to 9 to produce an aqueous solution of a melamine resin, for example, an aqueous solution of a melamine resin having a resin concentration of about 40 to 60% by weight;

To this, pulp is added in an amount of 20 to 45 parts by weight with respect to 100 parts by weight of the melamine resin, and a glycidyl compound such as s-butylphenol glycidyl ether is further added to 100 parts by weight of the melamine resin. 0.1 ~
3 parts by weight, kneaded, for example, about 70 to 10
It is dried at a temperature of about 0 ° C., for example, to obtain a popcorn-like pre-dried product having a diameter of about 3 to 0.5 cm, and if necessary, other organic or inorganic fillers, curing catalysts, inorganic or organic substances. The powdered melamine resin mixture can be obtained by pulverizing together with various compounds such as a pigment and a lubricant or a plasticizer.

The above-mentioned pulverizing treatment 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, pulverization may be further performed by means such as a ball mill, vibration mill, or tower mill. Commercially available molding powder containing pulp and melamine resin can also be used, and if desired, the 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, fluidized drying and the like.

The method for producing the powdery melamine resin mixture is the same as the above-mentioned method. For example, the glycidyl compound is not added or only a part thereof is added at the time of producing a popcorn-like pre-dried product. The rest or all can be added during the pulverization process.

As a method for producing the powdery melamine resin mixture, the aqueous melamine resin solution produced by the above-mentioned method is appropriately dried by a known method to obtain a powdery melamine resin as required. The compound and the various blends used as needed are mixed, for example, with a conventional mixer such as a V-type mixer, a super mixer, a Nauter mixer, a tumbler, an omni mixer, a Henschel mixer, a Loedige mixer, a ribbon blender, a planetary mixer and the like. A so-called dry method in which the mixture is homogeneously mixed using a mixer can be given.

Further, a method in which the above-mentioned wet method and the above-mentioned dry method are compromised may be employed. Examples of these methods include a popcorn-like pre-dried product by the wet method, powder or solid melamine resin, powder pulp, and the like. A method of pulverizing and mixing the glycidyl compound and the various compounds used as necessary by the pulverizing means, after pulverizing each of these components by means such as crushing in advance,
A method of mixing using the above mixer can be exemplified.

The granular composition for molding a melamine-based resin of the present invention is obtained by temporarily kneading the melamine-based resin mixture obtained as described above with an extruder, a heating roll machine, or the like, and then obtaining a preformed product. It is made by re-crushing.

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, a screen die type, and the like.
The twin-screw extruder may be either a co-directional twin-screw type or a different-direction 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 grinding 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 remilled product thus obtained has a particle size, preferably from JI, for ease of handling during molding and the like.
It is preferable that 80% by weight or more, more preferably 85% by weight or more of the S sieve that has passed through the 10 mesh sieve and not passed through the 100 mesh sieve is used. The heating and kneading conditions are 80 to 120 ° C and 10 to 30.
Seconds are preferred because they exhibit excellent performance as a granular composition for molding melamine-based resins.

The granular composition for molding a melamine resin according to the present invention can be used for compression molding, transfer molding, injection molding, etc.
The composition can be molded by a conventionally known method, and particularly exhibits excellent performance as a composition for automatic compression molding. In addition, the melamine-based resin particulate composition can be suitably used for multi-stage molding such as multicolor molding by compression molding or the like, molding with a pattern, surface coating molding, or the like.

[0065]

EXAMPLES Several examples of the present invention will be described in more detail with reference to Examples and Comparative Examples. In addition, various test methods and evaluation methods are as follows.

(1) Kneading and Extrusion Characteristics The torque during the heating and kneading of the powdery melamine-based resin mixture is measured using a Brabender mixer. Temperature 120 ° C, charge 24g, rotation speed 30rpm. The value of the torque over time of the charged resin mixture (kneaded material) is recorded, and the minimum torque value is measured. The smaller the value, the better, about 10
It is preferably not more than 00 g · m.

(2) Suitability for automatic weighing A 3 kg sample was placed on a straight body of 200 mmφ × 125 mm and a cone of 175 m in height.
m, Gently pour into the center of the hopper with a discharge damper with a discharge opening of 15mmφ. 100mm below the center of the outlet, J
Place a metal measuring cylinder for measuring the apparent density specified in IS K-6911-1979, fully open the damper, and fill the measuring cylinder with the sample. When the sample is sufficiently filled and spills around, the damper is closed and the sample in the measuring cylinder is weighed in the same manner as in the apparent density measurement method. According to this method, the weight is continuously measured 30 times (n), and the standard deviation S of these values is set as the automatic weighing suitability value.

[0068]

(Equation 1)

(3) Suitability for preheating tablet application High frequency preheater FDP320A made by Fuji Electric Co., Ltd., diameter 100 mmφ × height 25
The sample is subjected to high-frequency preheating using a polyethylene preheater ring and a glass fiber reinforced epoxy laminate plate (140 × 140 × 2 mm). The preheating condition at this time is a distance between the electrodes of 30 mm and an output of 2 kw at a frequency of 62 MHz.

A sample (100 g) is placed in a pre-heater ring placed on a laminate plate, flattened, and then subjected to high-frequency preheating. The preheated material obtained by such an operation is quickly taken out of the preheater while being placed on the laminate plate. The sample tableted by preheating is dropped freely from the inside of the preheater ring except for the laminate plate. The above operation is repeated to determine the number of times of preheating at which the weight of the deposit on the preheater ring becomes 5 g or more.

(4) Suitability for preventing dusting A sample of 100 g 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.

(5) 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.

[0073]

(Equation 2)

(6) 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. The sample is put into a conical shape using a metal cylinder having an inner diameter of about 50 mm and a height of about 10 mm, and is compression-molded 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 up to 1 mm with a dimension measuring instrument, and the average value is calculated to obtain the elongation (mm) of the sample.

(7) Test of minimum shaping characteristics Using a moldability test mold described in JIS K-6911, Section 5.4, mold temperature 150 ° C / 150 ° C, time required for mold clamping 15 seconds, no preheating Then, the minimum shaping pressure is determined under the condition without degassing.
The minimum shaping pressure is a minimum pressure that does not cause defective filling or cracks in a molded product, particularly at an edge portion, and is obtained by changing the pressure in units of 5 kg / cm ² and repeating molding several times.

Further, this value is an index indicating the flow characteristics in the mold. If this value is too low, there is a tendency that poor filling of the molded product into the thread jelly portion or the like tends to occur. About 80-120k
It is preferably about g / cm ² .

(8) Bleed-out Prevention A test piece having dimensions of 70 × 60 × 3 mm was molded at a mold temperature of 165 ° C./165° C.
Molding was performed under the conditions of ° C, a molding pressure of 200 kg / cm ² , and a curing time of 90 seconds. After taking out the molded product, the upper mold was removed and the specular gloss of the surface was measured. The measurement of glossiness is performed according to JIS Z-8741. The percentage of the specular gloss after molding the material to the specular gloss of the well-cleaned upper mold plating surface is evaluated as the bleed-out prevention property.

(9) Color Unevenness Prevention A 180 g sample preheated to 115 ° C. by a high frequency preheater was
Hydraulic press, mold temperature 165 ° C Supply to a lunch plate mold with a major axis of 30cm x minor axis of 20cm and a partition in the center, with a major axis of 30cm and a central axis of 5cm.
Each of them is stopped for 0, 2, 4, 6, 8, and 10 seconds, and then immediately pressurized to maintain the pressure at a gauge pressure of 40 kg / cm ² for 2 seconds and then degas. Then pressurize again, gauge pressure 100k
After curing at g / cm ² for 65 seconds, the molded article is taken out and allowed to cool. The state of color unevenness on the surface of 12 molded articles of the same sample formed in this way is visually evaluated, and the number of molded articles without color irregularity is used as the evaluation score.

(10) Mold Filling Property 500 g of a sample preheated to 115 ° C. by a high frequency
Hydraulic press, mold temperature 165 ° C, diameter 40cm, yarn thread diameter 1
Supplied to a 5cm high, 4cm high plate dies with a molding pressure of 210
Compression molding is performed in kg / cm ² for 120 seconds. The filling property of the molded product into the thread jig is visually determined according to the following evaluation criteria.・ ・ ・: Completely filled. ×: There are unfilled parts.

(11) Molded product surface gloss A test piece having a size of 70 × 60 × 3 mm is compression-molded (115
℃ high frequency preheating, molding temperature is 160 ℃, molding pressure is 210 kg / cm ² ,
Curing time 90 seconds). The gloss of the molded article is measured using a gloss meter TG-P manufactured by Tokyo Denshoku Co., Ltd. Measured at an incident angle of 60 ° C, the specular gloss of the glass surface with a refractive index of 1.567 is 100%
And measure the gloss.

(12) Crack resistance of molded product A bowl having a diameter of 6 inches and a weight of 120 g is compression-molded under the following conditions.

The rice bowl 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 obtained.

[0084]

[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 3-3 or more, and particularly preferably 4-1 or more.

(13) Impact resistance of molded article A flat plate having a diameter of 9 inches and a weight of about 150 g is compression-molded under the same conditions as in (12) crack resistance of the molded article.

The impact strength test is performed using the thus formed 9-inch flat plate. First, a 95 g steel ball is dropped 50 times from a height of 30 cm to a substantially central portion of the flat plate in a prone state. If a crack occurs during that time, the number of steel ball drops until the crack occurs is recorded (for example, if the 35th crack occurs, it is recorded as 30 cm-35 times).
If no cracks occur after dropping 50 times, increase the height.
Raise 10 cm (ie, from 40 cm height), repeat the above experiment, and record the height and number of times when cracks occurred (for example, drop a steel ball from 40 cm height, and crack 25 If it does, record 40cm-25 times).

(14) Heat resistance test The heat resistance test is performed in accordance with the “Appearance after heating” test in Section 5.23 of JIS K-6911. Melamine resin molding composition, mold temperature 160 ℃ / 16
0 ° C, molding time 3 minutes, diameter 50 ± 1mm without preheating,
A disc having a thickness of 3 ± 0.2 mm is formed. The test piece thus obtained is hung near a thermometer in a thermostat kept at a constant temperature, taken out after 2 hours, and examined for any remarkable appearance change such as cracks and blisters. The above test is conducted at different temperatures, and the maximum temperature within a range where no significant change in appearance occurs is defined as the heat resistance value.

Example 1 1260 g of melamine (manufactured by Yuka Melamine Co., Ltd .; Yuka Melamine)
(About 10 mol), 1379 g of 37% aqueous formalin solution (about 17 mol
Mol) and 900 g of water in a flask equipped with a reflux condenser,
The mixture was heated and reacted at 90 ° C. while stirring under the condition of F / M = 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 standard 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 of about 80 ° C. is added, stirred and cooled.

To 3,000 g of the melamine resin aqueous solution (solid content: about 50% by weight) thus obtained, 500 g of pulp (about 33 parts by weight based on 100 parts by weight of the melamine resin) was added, and s-butylphenol glycidyl ether (s- BPGE) 4 g (about 0.27 parts by weight based on 100 parts by weight of the melamine resin) was added and kneaded with a kneader, and the kneaded product was dried at 90 ° C. for 90 minutes with a hot air drier to obtain a pre-dried popcorn product. Was.

0.5 g of phthalic anhydride was added to 500 g of the pre-dried product.
2.5 g of zinc stearate was added, 4 g of Watching Red Mn was further added as a pigment, and the mixture was pulverized by a pot mill for 8 hours to obtain a powder of a melamine-based resin mixture for a dark red molded product.
Next, this resin mixture powder was heated and kneaded with a twin-screw extruder. The kneading extruder uses a screw having a shaft diameter of 55 mmφ, L / D = 20 and a compression ratio of 2.0, and the resin mixture powder supply rate is 20 kg / min.
And the cylinder temperature is 100 ° C and the screw speed is 100
Under the condition of rpm, a pre-molded product by heat extrusion and kneading was obtained.

[0092] The preform was roughly crushed and then crushed using an impact crusher having a screen diameter of 2 mm to obtain a granular composition for melamine resin molding. Table 1 shows the composition of the obtained granular composition for molding, and Table 2 shows various properties of the composition and various properties of the obtained molded product.

Examples 2 to 3 and Comparative Examples 1 and 2 A granular composition for molding melamine resin was obtained in the same manner as in Example 1 except that the amount of pulp was changed. Table 1 shows the composition of the obtained granular composition for molding, and Table 2 shows various properties of the composition and various properties of the obtained molded product.

Example 4 and Comparative Examples 3 and 4 The same procedure as in Example 1 was carried out except that the amount of the epoxy compound was changed to obtain a granular composition for molding a melamine resin.
Table 1 shows the composition of the obtained granular composition for molding, and Table 2 shows various properties of the composition and various properties of the obtained molded product.

Comparative Example 5 In Example 1, an epoxy compound (s-BP) was used as a modifier.
GE) A granular composition for melamine resin molding was obtained in the same manner except that 7.5 g of polyethylene glycol (PEG400) having an average molecular weight of 400 was used instead of 4 g. Table 1 shows the composition of the obtained granular composition for molding, and Table 2 shows various properties of the composition and various properties of the obtained molded product.

[0096]

[Table 2]

[0097]

[Table 3]

[0098]

Industrial Applicability The granular composition for molding a melamine resin of the present invention is a resin mixture comprising melamine / formaldehyde resin (a) and pulp (b) and epoxy compound (c) in specific amounts. Into a pre-molded product by heating and kneading, and re-crushing the pre-molded product, and has a good balance of improved properties mainly for compression molding of various melamine-based resin molded products. It is about improved.

In particular, the granular composition for molding a melamine resin of the present invention has heat resistance, hardness,
Equipped with improved automatic metering suitability of molding compositions in compression automatic molding without adversely affecting favorable properties such as high gloss, crack resistance, weather resistance, light resistance, stain resistance, and electrical properties. In addition, even in a molded product having a particularly large thread jig such as a platen plate, excellent molding aptitude exhibited by an appropriate flow characteristic and an appropriate minimum molding pressure characteristic in which the filling defect does not occur in the thread jig is obtained. Having, together with excellent moldability, hardly compatible molding aptitude, bleed-out prevention of the improver and releasability with excellent improvement effect,
There is no problem such as grain residue on the surface of the molded product, which tends to be present in the granular composition, and it is possible to obtain a molded product having an excellent appearance without color unevenness, even in a colored molded product in which color unevenness is particularly likely to occur. .

Continuation of the front page (56) References JP-A-2-227450 (JP, A) JP-A-1-115595 (JP, A) JP-A-1-101359 (JP, A) JP-A-59-8749 (JP) , A) JP-A-63-7911 (JP, A) JP-A-63-8423 (JP, A) JP-A-4-59860 (JP, A) JP-A-57-117533 (JP, A) 62-288012 (JP, A) JP-A-61-203159 (JP, A) JP-A-62-22848 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 61/20 -61/32 C08L 63/00-63/10 C08K 5/151-5/159 WPIDS (STN)

Claims (1)

(57) [Claims] 1. A resin mixture containing (a) 20 to 45 parts by weight of pulp and (c) 0.1 to 3 parts by weight of a monoglycidyl ether per 100 parts by weight of a melamine / formaldehyde resin. A granular composition for molding a melamine resin, which is obtained by re-crushing a heat-kneaded preformed product.