JPH07113064B2 - Granular melamine resin molding material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is a "granule" type granule having excellent improved properties, which is obtained by re-crushing a heat-extruded product of a melamine resin molding composition powder. Regarding melamine resin molding material,
In addition to excellent automatic weighing suitability (powder flowability) and turtle spot prevention, it also has excellent powder dust prevention suitability and collapse resistance.
The present invention relates to a granular melamine resin molding material exhibiting suitability for forming a preheated tapet (preparation of a preformed tablet), cold compression taper strength, molded article crack resistance and molded article impact resistance.

More specifically, the present invention is a granular melamine resin molding material obtained by re-crushing a heat extruded product of a melamine resin molding composition powder, and having a specific particle size distribution,
The present invention relates to a granular melamine resin molding material having a specific average hardness and a specific hardness variation.

[Conventional technology]

Conventionally, a melamine resin molding powder composition obtained by crushing a kneading and drying composition so-called "pop corn" containing a melamine resin liquid and pulp, and further, such a melamine resin molding composition powder It is known that once pelletized (or tabletted), it is re-crushed into coarse and fine granular molding particles, so-called "granule" type molding granule compositions.

In the former type of molding powder composition, usually 70% by weight or more of fine powder passing through 200 mesh sieves occupies, and the resulting hot-pressed molded product has the advantage that there is little trouble of turtledeck formation. However, on the other hand, there is a defect of dust (generation of dust), and there is a problem that the powder flowability is insufficient and the suitability for automatic weighing is poor. On the other hand, the latter "Granule" type molding powder composition exhibits satisfactory suitability for preventing dusting and powder flowability, but on the other hand, the resulting thermocompression-molded product has a problem of formation of turtle shells. .

Further, according to the study by the present inventors, in the former type of molding powder composition, prior to thermocompression molding of the composition, the composition is filled in a preheating frame and preheated by, for example, high frequency preheating. In the case of tapetting, the phenomenon of adhesion of molding powder to the inner wall of the preheating frame occurs, and complicated and time-consuming frame cleaning that requires cleaning is required. If this is not done, highly cured strips are often molded. It was discovered that there was a problem of mixing in the product and reducing the value of the molded product. On the other hand, in the latter case of the "Granule" type molding powder composition, the above trouble does not occur, but even if an attempt is made to form a preheated taplet compound, it is difficult to obtain a taplet compound having handleability, and the shape is destroyed. There is a difficulty in that a practical preheated tapette product cannot be formed. Therefore, a method of directly supplying into the molding die without hot preheating and adopting a method of thermo-compression molding is adopted, the disadvantage of extending the molding cycle cannot be avoided, and there is a problem that the formation of turtle shells is promoted. .

Heretofore, several proposals have been known for overcoming such troubles of the formation of turtle shells.

For example, in JP-A-51-79143, the hardness of the amino resin granular molding material is x (kg / cm ² ) and the particle size is y (mm), and the following formula y ≦ −1.23logex + 6.75 (A) y .Gtoreq.0.10 (B) x.gtoreq.5 (C) where the ratio occupied in the region surrounded by the three curves represented by the formulas (A), (B) and (C) is 80% or more. Amino resin granular molding material composition is proposed, which is disclosed to be useful for preventing the formation of turtle shells. Expressing the above particle size conditions in terms of mesh, the powder that does not pass the 145 mesh screen is 80% or more, that is, the powder that passes the 145 mesh screen is 20% or less, but the specific particle size distribution and the specific hardness in the present invention. There is no description or disclosure regarding variations, and in this proposal, the suitability for preheating taper,
No mention is made of cold compression tape strength, molded article cracking resistance and molded article impact resistance.

As another proposal, JP-A-57-46803 discloses the following particle size distribution 20 to 42 mesh particle size product 0 to 20% by weight 42 to 145 mesh particle size product 50 to 90% by weight 145 mesh particle size product 0 to 50% by weight An amino-based resin molding material in which% is an essential requirement has been proposed, and it is described that it is excellent in the prevention of the formation of turtle shell and in the automatic weighing property. As yet another proposal that can overlap with the above proposal for the same purpose as the above proposal, in JP-A-57-46804, an amino-based resin molding material occupied by only powder that passes 20 mesh screen and does not pass 145 mesh screen is disclosed. Are known. These proposals do not disclose at all an amino-based resin molding material having a specific average hardness and a specific hardness variation, which consists of a re-crushed product of a composition powder heated and extruded, and a particle size distribution. In addition, the material's collapse resistance, suitability for preheating taplets, cold compression taplet strength,
No mention is made of molded article cracking resistance or molded article impact resistance.

The present inventors previously conducted research for the purpose of solving incompatibility difficulties or troubles in the above-mentioned both types of melamine resin molding materials, and (a) to (c) as 100% by weight in total: Particle size distribution (a) 5 to 50% by weight of powder that passes through 24 mesh screens and does not pass through 42 mesh screens, (b) 17 to 47% by weight of powder that passes through 42 mesh screens and 145 through mesh screens, and (c) 145 A powder composition for melamine resin molding, characterized in that the powder passing through the mesh sieve satisfies 25 to 65% by weight and is a re-crushed product of the heat-extruded product of pulp and melamine resin-containing raw material powder for molding. Proposed by discovering that it is a powder composition for melamine resin molding that exhibits excellent prewetting suitability, cold compression tablet strength, and molded article crack resistance, as well as excellent automatic weighing suitability and turtle spot prevention property. did( HirakiAkira No. 59-8749).

As a result of further research, a particle size distribution different from that of the above-mentioned prior application, in particular, even in a region where fewer 145 mesh passes, a particle size distribution of 145 mesh non-passage, and the average hardness and hardness of the granular forming material. By selecting the variation width, it combines all the excellent properties of the proposal such as excellent automatic weighing suitability, turtle spot prevention, preheating tablet suitability, cold compression tablet strength and molded product crack resistance. At the same time, it was discovered that it could be a granular melamine resin molding material exhibiting further excellent powdering prevention suitability, disintegration resistance and molded article impact resistance, and completed the present invention.

[Structure of Invention]

That is, the present invention is a granular melamine resin molding material obtained by re-crushing a heat-extruded product of a melamine resin molding composition powder, wherein A has a particle size distribution of 100% by weight based on the total amount of the molding material. (A) Less than 3% by weight of those which do not pass through 24 mesh sieves, (b) 25 to 60% by weight of those that pass through 24 mesh mesh sieves and do not pass through 42 mesh sieves, and (c) pass through 42 mesh sieves and 145 mesh sieves. Non-sieving 25 to 60% by weight, (d) 145 mesh Sewage passing 10% or more and less than 24% by weight, and B, the hardness x (kg / cm ² ) of the molding material is When expressed by the formula (1-α) ≦ x ≦ (1 + α) (where, is the average hardness (kg / cm ² ) of the molding material, and α is an index representing the variation width of hardness), (kg / cm ² ) and α A, 80 ≦≦ 300 b, 0.3 ≦ α ≦ 0.7 are provided, and a granular melamine resin molding material is also provided. Of.

These and many other objects and advantages of the present invention will become more apparent from the description below.

As the melamine resin molding composition powder used for the preparation of the granular melamine resin molding material of the present invention, preferably, so-called popcorn is finely processed to a particle size suitable for heat extrusion molding.

Examples of such melamine resin-forming composition powder include, for example, a so-called melamine crystal powder 1 mol which can be produced by a method known per se such as a carbide method and a urea method, for example, a formalin aqueous solution having a concentration of 36% and / or In the form of paraformaldehyde, formaldehyde about 1
PH of about 7 in an aqueous medium at a reaction molar ratio of about 2 mol.
To about 9 to obtain a melamine resin liquid, for example, a melamine resin liquid having a resin solids concentration of about 40 to about 60% by weight of pulp (α-cellulose), based on the weight of the resulting composition powder. , For example, in an amount of about 20 to about 40% by weight, and optionally mixed with other additives and kneaded,
For example, it is dried at a temperature of about 70 ° to about 100 ° C. to form, for example, a so-called popcorn having a diameter of about 3 cm to about 0.5 cm, and a popcorn finely-treated product obtained by subjecting this to a fine-grain treatment is exemplified. it can.

The above-mentioned pulverization 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 hammer mill, further finely pulverizing with a means such as a ball mill, a vibration mill or a tower mill. Commercially available pulp and melamine resin-containing molding powder can be used, and if desired, the commercial molding powder can be further pulverized and used.

In the production of the melamine resin liquid, a part of the melamine can be replaced with another thermosetting resin-forming component capable of cocondensation. Examples of such components include benzoguanamine, acetoguanamine, guanamines such as CTU guanamine, thiourea, ureas such as urea, phenol,
Examples thereof include phenols such as xylenol, cresol, and bisphenol A, epoxy compounds, polyester compounds and the like. Such components are preferably used in an amount such that the preferred water resistance, chemical resistance, solvent resistance, arc resistance, etc. of the melamine resin are not substantially lost, for example, the same amount (weight) as melamine. Hereinafter, preferably, the amount used is 40% by weight or less based on the total weight of melamine and the thermosetting resin-forming component.

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, etc. can be illustrated.

Further, as the above-mentioned other additives, for example, titanium oxide,
Zinc oxide, zinc sulfide, red iron oxide, dark blue, barium sulfate,
Iron black, ultramarine, carbon black, lithopone, titanium yellow, cobalt blue, hansa yellow, benzidine yellow, lake red, aniline black, dioxazine violet, quinacridone red, quinacridone biolet, naphthol yellow, phthalocyanine blue, phthalocyanine green, etc. Inorganic or organic pigments such as; zinc stearate, zinc myristate, aluminum stearate, calcium stearate, butyl stearate, stearyl stearate, dioctyl phthalate, dibutyl phthalate, stearic acid amide, ε-caprolactam, oleic acid amide, Linoleic acid amide, polyethylene glycol, stearyl alcohol, polyoxyethylene stearate, glycerin,
Lubricants such as polyethylene glycol monooleate; phthalic anhydride, p-toluenesulfonic acid, dimethyl oxalate, dibenzyl oxalate, dimethyl phthalate, benzoyl peroxide, epichlorohydrin, triethanolamine salt of p-toluenesulphonic acid, 2-aminoethyl sulfonic acid, dimethyl chloride, aniline sulfonic acid, melamine oxalate, ammonium chloride, ammonium phosphate, trimethyl phosphate, acetamide, oxamide,
Examples of curing catalysts are as follows.

In the present invention, the particle size distribution requirements (a), (b), (c) and (d) are obtained by re-crushing a molded product obtained by subjecting the melamine resin molding composition powder as described above to heat extrusion molding. A granular melamine resin molding material that satisfies the above conditions.

The above heat extrusion molding can be performed using an extruder under appropriate temperature conditions. The type of extruder can be appropriately selected, and examples thereof include a single-screw extruder and a twin-screw extruder. The compression ratio and the temperature can be appropriately selected, for example, 1
A temperature ratio such as a compression ratio of about 3 to about 50 to about 130 ° C. can be exemplified. The extrusion end of the extruder may be of any type such as an open type or a screen die type, and the twin-screw extruder may be of the same-direction twin-screw type or different-direction twin-screw type.

Further, the heat extruded product can be roll pressed, if desired, prior to crushing.

In the present invention, the heat-extruded product of the composition powder that can be formed as described above is re-crushed to obtain a re-crushed product that satisfies the particle size conditions.

This re-shredding is such that the re-shredded product has a particle size distribution of (a) less than 3 wt% which does not pass the 24 mesh mesh sieve, and (b) passes 24 mesh mesh sieve, with the total amount of the molding material being 100 wt%. And 25 to 60% by weight of those which do not pass 42 mesh sieves, (c) 25 to 60% by weight of those which pass 42 mesh sieves and do not pass 145 mesh sieves, (d) 10% by weight or more of which pass 145 mesh sieves, It can be carried out by using any shredding means capable of forming a re-shredded material satisfying less than 24% by weight. If desired, sieving means can be used in combination. Examples of the crusher used for such crushing include an impact crusher, a hammer mill, an atomizer, a pin mill, a roll mill, and a pulverizer.

Furthermore, the granular melamine resin molding material of the present invention preferably has an angle of repose of 40 ° or more and less than 50 °. If the angle of repose is less than 40 ° and is too small, troubles of turtle shell development are likely to occur, and further, when preheating the taper, there is a tendency that the shape retention of the tablet is deteriorated and the angle of repose tends to be accompanied. If it exceeds 50 ° and is too large, the suitability for automatic weighing tends to deteriorate, and the suitability for preventing dusting may decrease, and further, the suitability for preheating tapetting tends to deteriorate. It is preferably 40 ° or more and less than 50 °.

In the reshredding treatment for producing the composition of the present invention as described above, other additives may be added, if desired.
Examples of such additives include the same pigments, lubricants, curing catalysts and the like as those exemplified as the additives which may be added when forming the raw material powder described above. Based on the weight of the composition of the present invention, a compounding amount such as about 10% by weight or less of pigments, about 5% by weight or less of lubricants, and about 5% by weight or less of curing catalysts can be exemplified.

The granular melamine resin molding material, which is a re-crushed product of the heat extruded product of the melamine resin molding composition powder of the present invention, has the particle size distribution requirements of the above (a), (b), (c) and (d). To be satisfied.

If more than 3% by weight of the material that does not pass the 24 mesh sieve of the requirement (a) is used in an excessive amount of 3% by weight or more, cold compression tablet strength will be deteriorated, and turtle shells will easily occur, and the crack resistance and impact resistance of the molded product Also decreases. If less than 25% by weight is less than 25% by weight that passes through the 24 mesh screen and does not pass through 42 mesh screen of the requirement (B), the suitability for automatic weighing and preheating tableting may be deteriorated. If the amount exceeds an excessive amount, crack resistance, impact resistance, cold compression tablet strength are deteriorated, and turtle spots are more likely to occur. If less than 25% by weight of the requirement (C) that passes 42 mesh sieves and does not pass 145 mesh sieves is too small, automatic metering suitability, crack resistance, and impact resistance become unsatisfactory. If the amount is too much over the weight%, the preheating tablet suitability and cold compression tablet strength will be deteriorated, and the crack resistance and impact resistance will be poor. Furthermore, if the amount of the material passing through the 145 mesh sieve of the requirement (d) is less than 10% by weight and the amount is too small, the crack resistance, impact resistance, cold compression tablet strength are deteriorated, and turtledeck spots are more likely to occur. ,
On the other hand, if the amount exceeds 25% by weight, the suitability for automatic weighing, suitability for preheating tablet, and dust-preventing property may deteriorate.

For the reasons described above, the particle size distribution is (a) less than 2% by weight of those which do not pass the 24 mesh screen, (b) 25 to 55% by weight of which passes through the 24 mesh screen and does not pass the 42 mesh screen, (c) It preferably satisfies 25 to 55% by weight of 42 mesh sieves and 145 mesh sieves not passed, and (d) 15% or more and less than 24% by weight of 145 mesh sieves.

Further, the hardness x (kg / cm ² ) of the re-crushed product of the heat-extruded product, which is the granular melamine resin molding material of the present invention, can be calculated by the following formula (1-α) ≦ x ≦ (1 + α) (however, When the average hardness of the material (kg / cm ² ) and α are the exponents that represent the variation width of hardness), (kg / cm ² ) and α are in the range of a, 80 ≦≦ 300 b, 0.3 ≦ α ≦ 0.7 It is necessary to be.

The above-mentioned hardness x and average hardness (kg / cm ² ) are measured by a method according to the Kiya-type as described later.

If the value is less than 80 and is too small, the collapse resistance of the crushed material may be deteriorated, the suitability for automatic weighing and the suitability for preheating tablet may be deteriorated. The inter-compressive tablet strength is deteriorated, turtlenecks are likely to occur during molding, and the crack resistance and impact resistance of the molded product tend to be deteriorated, which is not preferable.

If the value of α is less than 0.3 and is too small, the cold compression tablet strength tends to deteriorate, and the impact resistance of the molded product tends to be lowered. It is not preferable because the disintegration property of the product and the suitability for automatic weighing tend to decrease.

As described above, in the granular melamine resin molding material of the present invention, which is a re-crushed product of the heat-extruded product of the melamine resin molding composition powder, the requirements A (a), (b), (c) and ( It is essential that the particle size distribution condition of d) and the hardness conditions of requirement a and b are satisfied, and according to the present invention, for example, automatic metering suitability is preferably 2.0 or less, more preferably 1.8 or less, preheating Tableting suitability is preferably 15 cycles or more, more preferably 18 cycles or more, cold compression tablet hardness is preferably 40 kg / cm ² or more, more preferably 60 kg / cm ² or more, dusting prevention suitability is preferably 10%. Or less, more preferably 5% or less, and preferably has a collapse resistance of 5% or less.
% Or less, more preferably 3% or less, the crack resistance of the molded product is preferably 3-1 cycle or more, more preferably 3-
3 cycles or more, especially 4-1 cycles or more, the impact resistance of the molded product is preferably 60 cm-10 times or less, more preferably 6
It is possible to provide a melamine resin powder composition which has excellent properties such as 0 cm-30 times or more and has excellent improving properties without the risk of turtle spots.

In the present invention, the mesh size is the particle size determined by JIS.K-6911-1979.3.1 and is as follows.

I. Particle size measurement method (mesh sieving method) According to JIS.K-6911-1979.3.1, a sample of about 50g was sampled, and a rotor shaker, JIS.200φ standard sieve, rotor rotation speed 290 times / Min, 156 hits / min, total amplitude 28 mm
Sieve for 10 minutes. Then, the weight of the sample remaining on each sieve and the sample on the pan is measured, and the weight% is calculated.

In addition, the hardness x, the average hardness (kg / cm ² ) and the index of variation width (hereinafter sometimes referred to as variation index) α of the molding material of the present invention are measured as follows.

II. Method of measuring particle hardness Using a particle hardness meter with an improved mechanism that replaces the compression type load cell mechanism with the spring balance mechanism part of the Kiya type hardness meter, the voltage change of the load cell corresponding to the pressure change applied to the sample particles is electrically measured. To record. The particle hardness x is the load value (kg) at the yield point peak of the load (kg) -time (second) curve, and the projected cross-sectional area of the sample particle [Automatic area meter Luzex 210
(Measured using Nippon Regulator Co., Ltd.)] (kg / cm ² ). Sample passed 20 mesh and 42
Random sampling of 30 particles that did not pass through the mesh was used, and the remainder 20 excluding 5 values above and below the calculated value was used.
The maximum value Xmax. And the minimum value Xmin. Of X are determined, and the arithmetic mean value thereof is used, and the larger value of (Xmax −) / and (−Xmin) / is set to α.

Further, in the present invention, the angle of repose is determined as follows.

III. Angle of repose measurement 30 mm thick and 100 mm in diameter from the center of a glass circular table with a height of 100
After setting the outlet of the glass funnel (the diameter of the spout is 50 mm, the glass cylinder at the outlet is 7 mm, the length is 7 mm, and the height of the entire funnel is 57 mm) vertically at the position of mm, JIS.K- 6911
-Gently pour approximately 300g of sample through the glass funnel onto the glass round table according to the sampling method in 1979.3.1. If the sample is placed in a glass funnel, the diameter is 2 mm and the length is about 200.
Dispense using a mm copper stir bar. Measure the height h (mm) of the mountain formed on the circular platform and calculate the angle of repose (θ) The angle of repose is defined as the average value of the five measurements excluding the upper and lower (maximum and minimum) two measurement values out of the seven measurement values.

〔Example〕

Hereinafter, several embodiments of the present invention will be illustrated in more detail with reference to Examples together with Comparative Examples.

In the following, the test method and evaluation of automatic metering suitability (powder flowability) preheating tablet suitability, crack resistance, cold compression tablet strength are as follows.

(1) Suitability for automatic weighing: − In accordance with JIS K6911-1979, a 5 kg sample is randomly sampled.
Pour this gently into the center of a hopper with a discharge damper that has a straight body of 500 mmφ x 100 mm, a cone height of 500 mm, and a discharge part of 33 mmφ x 30 mm. 100 mm below the center of the outlet, JISK691
Place a measuring cylinder for measuring the apparent density made of metal specified in 1-1979, open the damper fully, and let the measuring cylinder fill the material. When the material is fully filled and spills around, close the damper and weigh the sample in the graduated cylinder in the same manner as the apparent density method. By this method, the weight is measured 50 times (n) continuously, and the standard deviation S of these values is taken as the automatic weighing suitability value.

Where n = 50 i = 1 to 50 yi = weight measurement value for each time (g) = arithmetic average value of all yi data (g) (2) preheating tablet suitability: -a sample of about 5 kg according to JIS K6911-1979 Randomly collect. This is a high frequency preheater FDP320A made by Fuji Electric, diameter 1
00mmφ x 25mm height polyethylene preheater ring and glass fiber reinforced epoxy laminate (140 x 140
X2mm) for high frequency preheating. As preheating conditions at this time, the distance between the electrodes is 30 mm, the output is 2 KW, and the frequency is 62 MHz.
130 g of the sample was placed in a pre-heater ring placed on a laminate plate, leveled, and then preheated by high frequency. The preheated product obtained by such an operation is put on the laminate plate and immediately taken out from the preheater. The laminate plate is removed, and the sample that has been tabletted by preheating is allowed to fall freely from inside the preheater ring. Repeat the above operation to find the number of preheating times when the weight of the deposit on the pre-heater ring becomes 5 g or more.

(3) Cold compression tablet hardness: A sample of -50 g was placed in a cylindrical tablet mold having a diameter of 50 mm and a height of 200 mm and having a cylindrical capacity, and a pressure of 700 kg / cm ² was applied for 10 seconds at room temperature to press the tablet. Mold. The surface hardness of this tablet was determined using a Barcol hardness tester.

(4) Dust prevention suitability: -A 100 g sample is randomly sampled in accordance with JIS K6911-1979. Gently pour this into a glass cylindrical container as shown below. The cylindrical container has an inner diameter of 50 mm and a height of 500 mm, and a No. 2 glass filter with a layer thickness of 5 mm is attached to the lower part of the container so that dry air can be blown in from the lower part of the container. Blow dry air from the bottom of the container containing 100 g of sample at a flow rate of 1 / min for 1 minute. By this operation, the weight loss rate (%) spilled out is obtained, and it is determined as the dusting suitability.

(5) Disintegration resistance A sample of about 100 g was sampled and a rotor shaker, JIS.20
Rotational speed 290 times / on a 0 mesh 80 mesh standard sieve
Sieving is performed for 10 minutes under the condition that the impact is 156 times per minute and the total amplitude is 28 mm. Next, the weight of the sample on the undersize pan is measured, and thereafter, the sieving operation is continued for another 6 hours, the weight of the sample on the undersize pan is measured again, and the disintegration rate is calculated according to the following calculation formula. And the value of collapse resistance.

Where W ₀ = total sample weight (g) W _10M = sample weight under sieving after 10 minutes (g) W _6H = sample weight under sieving after 6 hours (g) (6) Molded product Crack resistance A bowl with a diameter of 6 inches and a weight of 120 g is compression-molded under the following conditions.

Mold temperature 165 ° C (upper mold) 160 ° C (lower mold) Pressure 180kg / cm ² Preheating time 60 seconds Degassing time 0.5 seconds Molding time 60 seconds Molded bowl like this, one cycle next cycle As a result, four cycles per day are performed, and the number of cycles and the number of days until the crack enters are calculated.

The indication of crack resistance is expressed as (number of days)-(number of cycles), and if it is 2-3, for example, the occurrence of cracks at the third cycle on the second day is indicated.

As the crack resistance, 3-1 or more is preferable, and 4-1
The above is particularly preferable.

(5) Impact resistance of molded product A flat plate having a diameter of 9 inches and a weight of about 150 g is compression-molded under the same conditions as (4) Crack resistance of the molded product.

An impact strength test is conducted using the 9-inch flat plate thus formed.

First, about 90 g of a steel ball is dropped 50 times from a height of 50 cm to the center of the flat plate in the prone state. If a crack occurs during that time, record the number of steel ball drops until the crack occurs (for example, if the crack occurs at the 35th time, record it as 50 cm-35 times). If the crack does not occur even if dropped 50 times, raise the height by 10 cm (that is, from a height of 60 cm), repeat the above experiment, and record the height and the number of times when the crack occurs (for example, If a steel ball is dropped from a height of 60 cm and a crack occurs at the 25th time, 60
Record as cm-25 times).

Reference example Melamine (Oilized Melamine Co., Ltd .; oiled melamine) 1260
g, 1380 g of a 37% aqueous formalin solution and 900 g of water were placed in a flask equipped with a reflux condenser, and heated and reacted at 90 ° C. with stirring under the condition of F / M = 1.7. The cloud point of the melamine resin liquid is 60.
When the temperature reached ℃, 1.2 g of NaOH was added and cooled to obtain a melamine resin initial condensate. The cloud point used as a guide for the end of the reaction is the temperature at which cloudiness occurs when 5 ml of resin solution is sampled and 45 ml of hot water at about 80 ° C. is added and stirred and cooled.

The melamine resin initial condensate thus obtained (solid content of about 50
(Wt%) 2500 g of pulp (460 g (about 27 wt% based on the total amount of solid content of melamine resin and pulp)) and kneading with a kneader, and then drying this kneaded product at 90 ° C for 90 minutes with a hot air dryer. Then, popcorn was obtained.

To this popcorn 500g titanium oxide 5g, phthalic anhydride
0.5 g of zinc stearate and 2.5 g of zinc stearate were added, and the mixture was pulverized with a pot mill for 8 hours to obtain a melamine resin molding composition powder having a pulp content of 26%.

Example 1 The melamine resin molding composition powder obtained in Reference Example was then heated and kneaded with a co-rotating twin-screw kneading extruder to obtain a kneaded melt. The kneading extruder uses a screw having a shaft diameter of 55φ, L / D = 20, and a compression ratio of 2.0, the composition powder supply rate is 20 kg / min, the cylinder temperature is 100 ° C., and the screw rotation speed is 100 rpm. Then, a heat extruded kneaded melt-molded product was obtained.

The kneaded product was roughly crushed and then crushed using an impact crusher having a screen diameter of 2 mmφ to obtain a granular melamine resin molding material.

24 mesh pass of the melamine resin molding powder composition,
After passing through 24 mesh sieves, 42 mesh passes, 42 mesh passes, 145 mesh pass, and 145 mesh pass weight%,
Test result of angle of repose, automatic metering suitability of powder composition for melamine resin molding, suitability for preheat tableting, tablet strength, molded article crack resistance and molded article impact resistance
Shown in the table.

Examples 2 and 3 and Comparative Examples 1 to 5 Melt-molded products obtained by the kneading extrusion method were obtained in the same manner as in Example 1, and granular melamine resin molding materials were prepared by changing the coarse and fine conditions and the reshredding conditions. The molding materials of Comparative Examples 1 to 5 were also produced according to this method.

Table 1 shows the particle size, average hardness, hardness variation index, repose angle, and performance measurement results of these materials.

Examples 4 to 6 and Comparative Examples 6 to 9 Granular melamine resin molding materials were produced in the same manner as in Example 1 except that L / D of the screw of the kneading extruder and different compression ratios were used.

Table 1 shows the particle size, average hardness, hardness variation index, repose angle, and performance measurement results of these materials.

Comparative Example 10 Regarding a commercially available granular melamine resin molding material (manufactured by Company A),
Table 1 shows the particle size, average hardness, hardness variation index, angle of repose, and performance measurement results.

Claims (2)

[Claims] 1. A granular melamine resin molding material obtained by re-crushing a heat extruded product of a melamine resin molding composition powder, wherein A has a particle size distribution of 100% by weight of the total amount of the molding material. (A) Less than 3% by weight of those which do not pass through 24 mesh screens, (b) 25-60% by weight of those that pass through 24 mesh screens and do not pass through 42 mesh screens, (c) pass through 42 mesh screens and 145 mesh screens of Non-passage 25 to 60 wt%, (d) 145 mesh sieve Passing 10 wt% or more and less than 24 wt%, and further, B, the hardness x (kg / cm ² ) of the molding material is When expressed by the formula (1-α) ≦ x ≦ (1 + α) (where, is the average hardness (kg / cm ² ) of the molding material, and α is an index representing the variation width of hardness), (kg / cm ² ) and α Is a, 80 ≦≦ 300 b, 0.3 ≦ α ≦ 0.7, and a granular melamine resin molding material is characterized. 2. The angle of repose of the granular melamine resin molding material is
The granular melamine resin molding material according to claim (1), which is 40 ° or more and less than 50 °.