JPH0570665B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention is directed to an improved melamine-based resin that exhibits excellent improved properties and has a well-balanced combination of these properties for use in molding melamine-based resin molded products such as various compression molded products. The present invention relates to a resin molding composition. In particular, the present invention provides a melamine-based resin molding composition without adversely affecting its desirable properties such as heat resistance, hardness, high gloss, crack resistance, weather resistance, light resistance, stain resistance, and electrical properties. , has excellent moldability shown by appropriate disk flow characteristics and appropriate minimum molding pressure characteristics, and has excellent mold release properties when opening the mold at the initial stage of pressurization such as foil insertion molding. The present invention relates to a melamine resin molding composition. [Prior Art] Conventionally, melamine-based resin molding compositions have generally been produced by mixing melamine alone or with melamine and another cocondensable amino compound at a pH of about 7 to 9 and a reaction temperature of about
Add pulp to the so-called initial condensation resin liquid obtained by reacting at 85 to about 95°C for a reaction time of about 30 minutes to about 1 hour, etc. so that the pulp amount accounts for about 20 to 50% by weight, and knead. After drying and forming popcorn, curing agents, lubricants, pigments, fillers, etc. are added to the popcorn, and the popcorn is crushed. Tableware, electrical parts, etc. are molded from the molding composition.
Such molding melamine resin compositions generally contain 165
At high temperatures of ~180℃ and high pressures of 200Kg/ ^cm2 to 250Kg/ ^cm2 ,
In addition, it is molded into a molded article under conditions that the molding time is approximately 30 seconds or less. However, with energy conservation in recent years, 130~
There has been a need for a melamine resin molding composition that can be molded at a low temperature of about 160° C. and a low pressure of about 20 to 100 kg/cm ² . When the above-described conventional melamine resin molding composition is subjected to the low-temperature and low-pressure molding conditions to form a molded product, unfilled molding material, mold release, gloss,
There are disadvantages in that stain resistance and crack resistance tend to deteriorate, making it difficult to obtain molded products that can be put to practical use, and the above-mentioned high-temperature and high-pressure molding conditions have been considered unavoidable. In order to solve the above-mentioned problem that it is difficult to obtain a molded product exhibiting performance that can be put to practical use when molding a conventional melamine-based resin molding composition under the low temperature and low pressure conditions, the present inventor has developed a wide variety of molding compositions. We have conducted repeated research on As a result, when using a new melamine resin molding composition containing a specific melamine resin that undergoes relatively high condensation and a specific range of amounts of pulp, polyethylene glycol, and metal soap, it is possible to use the above-mentioned low temperature and low pressure conditions. However, they made the surprising discovery that the melamine-based molded product can be easily molded and exhibits various properties such as excellent crack resistance and heat resistance, which led to the completion of the present invention. Conventionally, several proposals regarding the use of polyoxyalkylene modifiers have been known in the field of melamine resin technology. For example, in Japanese Patent Publication No. 36-22883, for the purpose of reducing mold-shrinkage and after-shrinkage, polyoxyalkenes such as Modified urea with low shrinkage, especially after molding, characterized by adding polyethylene glycol with a molecular weight of 200 to 1500 or polypropylene glycol with a molecular weight of 150 to 500 as a modifier in an amount of about 0.5 to 7% to the molding material. A method for producing a melamine resin molding material has been proposed. However, the first proposal above only exemplifies polyethyl glycol with a molecular weight of 200 to 1,500, which is different from the present invention, as being the most effective and yielding good results in various respects. Ease of molding under low temperature and low pressure conditions and excellent crack resistance and heat resistance of the resulting molded products using a relatively highly condensable melamine resin and a specific amount of metal soap, which are essential requirements of the invention, have been achieved. There is no suggestion of any special effects that can be achieved. In tests based on the type and amount of polyethylene glycol disclosed in the above proposal, and the amount of metal soap, it was found that even if the relatively highly condensed melamine resin of the present invention was used, the above-mentioned ease of molding and Completely unsatisfactory results such as the properties of the molded product can be obtained. In addition, in Japanese Patent Publication No. 39-1808, degassing during the molding process is facilitated, and formaldehyde,
In order to prevent undesirable gaseous substances such as water from remaining and forming a "striped" pattern, which reduces its commercial value and quality, and at the same time improve the moldability of the molding material, amino resin initial condensate and fillers such as pulp, curing catalysts, lubricants, plasticizers,
When producing amino resin molding materials from coloring agents or other additives,
A method for producing an amino resin molding material has been proposed, which is characterized by using an initial condensate solution to which 0.1 to 10% polyethylene glycol (average molecular weight 2000 to 10000) is added at any stage of the reaction. The above-mentioned second proposal also does not provide any suggestion or disclosure regarding the above-mentioned special effects due to the relatively highly condensed melamine resin of the present invention and a specific amount of metal soap. Even if the second proposal uses a polyethylene glycol modifier having a higher molecular weight than the first proposal, the above problem cannot be solved. [Structure] The melamine resin molding composition of the present invention has ()
The following (a) and (b) (a) melamine/formaldehyde resin, and (b) the above (a) melamine/formaldehyde resin, (a) urea/formaldehyde resin, and/or (b) ureas. 100 parts by weight of a melamine resin selected from the group consisting of a mixed resin consisting of () 0.4 to 3 parts by weight of polyethylene glycol with an average molecular weight of 2,000 to 10,000, () 25 to 65 parts by weight of pulp, and () 0.4 parts by weight of metal soap. ~4 parts by weight of the melamine resin molding composition.
A melamine-based resin molding composition characterized by having a clouding point of 14 to 93°C using a 20% by volume aqueous dimethyl sulfoxide solution. It is. The melamine/formaldehyde resin of the above constituent requirements ()(a) may be melamine alone or together with melamine,
For a mixture of ureas and/or a melamine cocondensation component consisting of melamine and other amino components other than ureas, formaldehyde alone or formaldehyde and one or more of other aldehyde components other than formaldehyde may be used. This is a melamine/formaldehyde resin obtained by subjecting a mixture of the following to a condensation reaction to a cloudy point in a specific range using a known method. Examples of the above-mentioned ureas include urea, thiourea, and ethylene urea, and examples of the above-mentioned melamine cocondensation component include guanamines such as benzoguanamine, formguanamine, acetoguanamine, phenylacetoguanamine, and CTU guanamine. and other amino compounds such as guanidine, dicyandiamide, and para-toluenesulfonamide. The amount of the ureas and/or melamine co-condensation component to be used is up to 0.7 mol per 1 mole of melamine, preferably within the range of the urea and/or melamine co-condensation component used. It is best to use it within a range that does not exceed the working weight. If the amount of urea and/or melamine cocondensation component exceeds 0.7 mol per 1 mol of melamine, the light resistance, weather resistance, heat resistance, stain resistance, etc. of the resulting melamine-based molded product tend to decrease, so it is preferable. do not have. In addition, other aldehyde components other than the formaldehyde include, for example, aliphatic aldehydes such as acetaldehyde, propionaldehyde, and butyraldehyde; aromatic aldehydes such as benzaldehyde; furfural; and other melamine ureas and melamine cocondensation components. Examples include aldehyde compounds other than formaldehyde that are capable of addition and condensation. The amount of other aldehyde components other than the above formaldehyde is based on 1 mole of formaldehyde.
The amount is up to 0.5 mol, and it is preferable to use the aldehyde component within a range that satisfies the above usage amount range and at the same time does not exceed the usage weight of formaldehyde. When the amount of other aldehyde components other than formaldehyde exceeds 0.5 mol per 1 mol of formaldehyde, the melamine,
This is undesirable because the reactivity of addition and condensation with ureas and melamine cocondensation components tends to decrease, and the curing speed of the resulting melamine resin molding composition may also decrease, which is undesirable. In the present invention, the term "formaldehyde" includes compounds, such as paraformaldehyde, which substantially act as formaldehyde during the addition/condensation reaction with the melamine, ureas, and melamine cocondensation component. It is a name. The melamine/formaldehyde resin (a) is preferably a melamine/formaldehyde resin or a melamine/urea/formaldehyde cocondensation resin, which may contain up to 0.7 mole of urea per mole of melamine. Next, as for the mixed resin of the constituent requirements () and (b), for the melamine/formaldehyde resin of (a), (a) the above-mentioned urea alone or the urea and melamine, and a mixture other than the urea. Addition and condensation reaction of formaldehyde alone or one or more of the above-mentioned other aldehyde components other than formaldehyde to a mixture with a urea cocondensation component consisting of other amino components by a method known per se. The resulting urea/formaldehyde resin (b) is a specific mixed resin obtained by blending the above-mentioned ureas and/or both (a) and (b). Examples of the urea cocondensation component include the same compounds as the melamine cocondensation component. The amount of the urea cocondensation component used in the urea/formaldehyde resin in (a) above is up to 0.5 mol per 1 mol of urea, and preferably, while satisfying this usage amount range, the urea cocondensation component is It is preferable to use the components within a range in which the weight used does not exceed the weight used of urea. If the amount of the urea cocondensation component exceeds 0.5 mol per 1 mol of urea, the light resistance etc. of the resulting melamine molded product tends to decrease, which is not preferable. In addition, other aldehyde components other than formaldehyde in the resin (a) include aliphatic aldehydes similar to those mentioned in the case of the melamine/formaldehyde resin in (a); aromatic aldehydes; furfural; and other ureas mentioned above. and addition/addition with other amino components other than melamine and urea.
Mention may be made of aldehyde compounds other than formaldehyde that can be condensed. The amount of other aldehyde components other than the above formaldehyde is based on 1 mole of formaldehyde.
The amount is up to 0.5 mol, and it is preferable to use the aldehyde component within a range that satisfies the above usage amount range and at the same time does not exceed the usage weight of formaldehyde. When the amount of other aldehyde components other than formaldehyde exceeds 0.5 mol per 1 mol of formaldehyde, the reactivity of addition and condensation with the ureas and melami as well as other amino components other than ureas tends to decrease. Moreover, the curing speed of the resulting melamine resin molding composition may also be reduced, which is not preferable. In addition, also in the mixed resin (b), formaldehyde refers to a compound, such as paraformaldehyde, that substantially acts as formaldehyde during the addition/condensation reaction with the urea, melamine, and other amino components other than urea. This is a name that includes compounds. The ureas mentioned in (b) above include 1 of the above mentioned ureas.
More than one species can be used alone or in combination, and from the viewpoint of moldability such as disk flow characteristics and minimum shaping pressure characteristics, and light resistance of the resulting molded product,
Preferably, urea is used alone. The mixed resin in (b) above is melamine/formaldehyde resin, which is an addition/condensation product of melamine alone and formaldehyde alone, in (a), and urea formaldehyde, which is an addition/condensation product of urea alone and formaldehyde alone. A mixed resin obtained by blending resins and a mixture obtained by blending urea with the melamine/formaldehyde resin (a) are preferred. Further, the amount of urea in the mixed resin is up to 0.7 mol per mol of melamine, and if the amount of urea exceeds 0.7 mol per mol of melamine,
This is not preferable because the heat resistance and stain resistance of molded products made using the resulting melamine resin molding composition tend to decrease. Furthermore, the melamine/formaldehyde resin of (a) and the melamine/formaldehyde resin of (b) are blended with both or either of the urea/formaldehyde resin of (a) and (b) ureas. In the melamine-based resin selected from the group consisting of a mixed resin made of
It is preferable that the number is 2 or less. When the molar ratio exceeds 2, the molded product tends to become brittle, and properties such as crack resistance may deteriorate. If the molar ratio is less than 1, the curing speed of the resulting melamine resin molding composition tends to decrease, and the melamine molded product may also have a bad "shad" condition. The () melamine resin includes (a) a melamine/formaldehyde resin in the resin, a melamine/urea/formaldehyde co-condensed resin, and (b) a mixed resin in which the melamine/formaldehyde resin is blended with a urea/formaldehyde resin or urea. is preferred. The average molecular weight (hereinafter, abbreviated as PEG) of polyethylene glycol (hereinafter abbreviated as PEG) of the above constituent elements ()
(abbreviated as ) requires 2000 to 10000,
4000-6000 is preferred. If the above is less than 2000, the disc flow characteristics, minimum molding pressure characteristics, mold releasability, etc. of the melamine resin molding composition obtained by blending with the melamine resin of the above constituent requirements () are unsatisfactory. This is undesirable because it tends to occur. In addition, when n exceeds 10,000, the disk flow characteristics, minimum molding pressure characteristics, etc. of the melamine resin molding composition tend to become unsatisfactory, which is not preferable. The amount of PEG (constituent element ()) blended in the melamine resin (constituent element ()) of the present invention is 0.4 to 3 parts by weight based on 100 parts by weight of the melamine resin. If the above-mentioned amount exceeds 3 parts by weight, the disc flow characteristics, minimum molding pressure characteristics, and crack resistance of the resulting melamine-based molded product tend to decrease, which is not preferable, and if the amount exceeds 0.4 parts by weight, it is not preferable. Even if it is less than that, the disk flow characteristics, minimum molding pressure characteristics, etc. tend to deteriorate, which is not preferable. The pulp in the above component () usually refers to paper,
It refers to a chain polymer whose main component is α-cellulose obtained from cellulose raw materials, which is used as a raw material for chemical fibers, cellulose plastics, etc.In general, industrially, fibers made from cellulose raw materials processed from wood and linter are used. A cardboard-like material is used. The blending amount of the pulp is determined based on molding suitability such as disk flow characteristics and minimum molding pressure characteristics, and mechanical strength such as crack resistance and bending strength of the resulting melamine molded product. for the department
20-80 parts by weight are required. Pulp content is 20
If it is less than 80 parts by weight, the bending strength tends to decrease, and if it exceeds 80 parts by weight, the above-mentioned moldability may deteriorate, which is not preferable. Preferably, 30 to 60 parts by weight can be used per 100 parts by weight of the melamine resin. Furthermore, the metal soap of the above component () is a salt of a fatty acid having 12 to 22 carbon atoms and zinc, and typically includes lauric acid, myristic acid, palmitic acid, stearic acid, anichic acid, and behenin. Examples include salts of fatty acids such as acids and metals such as calcium, barium, aluminum, zinc, and mixtures thereof. Among these, it contains 50% by weight or more of ``zinc stearate,'' which is a salt of zinc and a fatty acid called ``stearic acid,'' which is solid at room temperature and mainly consists of stearic acid and palmitic acid (50% by weight or more). It is preferable that
Particularly preferred is "zinc stearate" containing 70% by weight or more. The amount of the above metal soap to be used is determined based on the synergistic effect with PEG on the moldability.
0.4 to 4 parts by weight is required per 100 parts by weight of the melamine resin. If the amount used is less than 0.4 parts by weight, it will not work synergistically with PEG, making it difficult to obtain the desired moldability, while if it exceeds 4 parts by weight, the resulting melamine-based molded product will have good crack resistance and stain resistance. This is undesirable as it reduces the performance of the product. The melamine resin molding composition of the present invention contains 20% by volume dimethyl sulfoxide (hereinafter referred to as
The white turbidity point measured using an aqueous solution (sometimes abbreviated as DMSO) must be in the range of 14 to 93°C. In the present invention, "20 melamine resin molding compositions"
"White turbidity point measured using volume% DMSO aqueous solution"
Collect 15g of a melamine resin molding composition that can be finely ground using a mixer, etc., and add 20% by volume to this.
Add 20 ml of DMSO aqueous solution and shake, add IN-NaOH aqueous solution and adjust the pH to 9 using PH test paper, then knead well for 5 minutes in a 60°C hot water bath. This mixture is immediately filtered using a Buchner funnel to collect the filtrate. To 0.5ml of filtrate that can be collected
Add 4.5 ml of a 20 volume % DMSO aqueous solution, heat to about 100°C, and then gradually cool it. The temperature at which the aqueous solution becomes cloudy is measured and determined as the cloudy point. When the cloudiness point is less than 14°C, when the melamine resin molding composition is molded, a large amount of gas is generated, and the melamine molded product tends to have a bad "cold".
In addition, mold releasability tends to deteriorate, which is undesirable.
If the temperature exceeds 93°C, moldability such as disk flow characteristics and minimum molding pressure tends to be insufficient, which is not preferable. The clouding point is preferably 30 to 85°C, particularly preferably 45 to 80°C, depending on the above-mentioned moldability, mold releasability, appearance of the molded product, etc. In addition, the melamine resin molding composition of the present invention has the following properties to the extent that the performance of the composition is not impaired:
Depending on the desired purpose, organic or inorganic fillers such as rock wool, glass fibers, synthetic fibers, calcium carbonate, talc, clay, silica, etc.; phthalic anhydride, p-toluenesulfonic acid, oxalic acid, dimethyl, dibenzyl oxalate, Dimethyl phthalate, benzoyl peroxide, epichlorohydrin, p-toluenesulfonic acid triethanolamine salt, 2-aminoethylsulfonic acid, dimethylaniline sulfonic acid hydrochloride, melamine oxalate, ammonium chloride, ammonium phosphate, trimethyl phosphate, acetamide , oxamide, etc.; titanium oxide, zinc oxide, zinc sulfide, red iron oxide, navy blue, barium sulfate, iron black, ultramarine, carbon black, lithopone, titanium yellow, cobalt blue, Hansa yellow, benzidine yellow,
Inorganic or organic pigments such as lake red, aniline black, dinoxazine violet, quinacridone red, quinacridone violet, naphthol yellow, phthalocyanine blue, phthalocyanine green, etc.; butyl cetearate, stearyl stearate, dioctyl phthalate, phthalic acid. dibutyl, stearamide,
Lubricants such as ε-caprolactam, oleic acid amide, linoleic acid amide, stearin alcohol, polyoxyethylene stearate, glycerin, polyethylene glycol monooleate, etc.;
etc. can be added and blended. The melamine resin molding composition according to the present invention is
It can be suitably made by the so-called wet method as described below. For example, about 1 to about 2 moles of formaldehyde in the form of a formalin aqueous solution and/or paraformaldehyde with a concentration of 36% per mole of so-called melamine crystal powder that can be produced by a method known per se such as the carbide method or the urea method. For example, pulp (α - Cellulose), for example, about 30 parts by weight per 100 parts by weight of the solid content of the melamine resin liquid.
~Add to about 60 parts by weight, and add an additional 2000~
10,000 PEG is blended in an amount of 0.4 to 3 parts by weight based on 100 parts by weight of solid content of the melamine resin liquid,
Popcorn is kneaded and dried at a temperature of, for example, about 70°C to about 100°C to form so-called popcorn with a diameter of about 3cm to about 0.5cm, which is then processed into powder. get. The above-mentioned pulverization treatment can be carried out using, for example, an impact hammer mill, a ball mill, a vibration mill, or a tower mill. If desired, the powder may be pre-pulverized using, for example, an impact hammer mill, and then further processed into fine powder using a means such as a pole mill, a vibration mill, or a tower mill. Commercially available pulp and molding powder containing melami resin can also be used.
If desired, a commercially available molding powder may be further pulverized and used. As the kneading means for forming the popcorn, a kneader, a co-kneader, etc. can be used, and as the drying means, hot air drying, band dryer drying, fluidized drying, etc. can be exemplified. Note that the term "powder" here is not limited to finely processed powder, but any powder with a particle size that can be used for molding without any problem, even if it is in granule form, can be used. can do. The granular product obtained as described above is heated and kneaded using an extruder, heated roll machine, etc., and the resulting preforming composition is re-pulverized to a particle size range suitable for handling during molding. It is preferable to use it as a melamine resin molding composition. At this time, in the above-mentioned heating and kneading, any appropriately selected extruder can be used without particular limitation, and examples thereof include a single-screw extruder, a twin-screw extruder, and the like. The compression ratio and temperature can be selected as appropriate, for example, a compression ratio of 1.1 to 3, about 50 to about 130℃
Examples of temperature conditions include: The extrusion end of the extruder may be of any type, such as an open type or a screen-like die type, and the twin-screw extruder may be of either a twin-screw type in the same direction or a twin-screw type in different directions. Further, the type of heating roll machine can be selected as appropriate. The pre-composition for molding obtained by heating and kneading can be re-pulverized using any re-grinding means that can form a re-pulverized product. If desired, sieving means can be used in combination. Examples of the crusher used for such re-grinding include impact crushers, hammer mills, atomizers, pin mills, roll mills, pulpizers, and the like. The re-pulverized product thus obtained preferably has a particle size of:
8% by weight or more of materials that can pass through a 10 mesh JIS sieve and not pass through a 100 mesh sieve, more preferably 85% by weight
% by weight or more is preferable. Further, heating and kneading conditions of 80 to 120° C. for 10 to 30 seconds are preferable because excellent performance is exhibited as a melamine resin molding composition. The melamine resin composition also exhibits excellent automatic metering suitability. The melamine resin molding composition of the present invention can be molded into a desired molded article using known techniques such as compression molding, transfer molding, injection molding, and the like. As mentioned above, the melamine-based resin molding composition of the present invention has a well-balanced combination of improved properties such as excellent moldability, bleed-out prevention properties, and mold release properties, so it can be used, for example, in tableware, etc. When performing multi-stage compression molding such as molding with different colors on the inside and outside, molding with patterns using decorative foil, and surface coating molding, it is possible to significantly shorten the molding cycle without having problems with molding defects, and improve productivity. Helpful. For example, when molding with a pattern by three-stage compression molding, the mold is opened so that decorative foil can be placed on the first-stage molded product only after the first-stage molding is performed after the initial pressure operation and the subsequent degassing operation. becomes possible,
After placing the foil, the mold is closed and second stage molding is performed, then the mold is opened again and a surface coating glaze is supplied, and the mold is closed and third stage molding is performed to produce the final molded product. It's normal. In such three-stage compression molding, when a conventional melamine resin molding composition is used, the total pressing time is about 45 to 90 seconds, and the molding cycle is about 180 to 220 seconds. However, since the melamine resin molding composition of the present invention has excellent moldability and mold release properties in a well-balanced manner as described above, the initial pressure operation can be virtually omitted and the first stage molding can be carried out. After the first stage molding, it is possible to open the mold and perform degassing and foil placement at the same time, and the time for holding the first stage molding pressure can be greatly shortened, so the total pressurizing time is approximately twenty five
It is possible to carry out three-stage compression molding, which is industrially extremely advantageous, with a molding cycle time of about 125 to 165 seconds. Furthermore, there is no risk of surface level difference between the part covered with foil and the part not covered with the molded product, a molded product with excellent uniformity of glaze layer thickness can be obtained, and there is no risk of overcure. Benefits such as: [Examples and Test Methods] Hereinafter, several embodiments of the present invention will be explained in more detail by giving examples as well as comparative examples. In addition, disc flow characteristics, minimum molding pressure characteristics, mold release properties,
The test method and evaluation of the crack resistance and heat resistance of the molded product are as follows. (1) Disc flow characteristics test Using the disc type test mold shown in Section 5.3.2 of JIS K6911, 5 g of sample was heated at a mold temperature of 150 ± 3°C.
Using a metal cylinder with an inner diameter of about 50 mm and a height of about 10 mm, the sample is placed into a conical shape approximately in the center of the mold, which is maintained at a constant temperature, and compression molded within 15 seconds under a load of 2000 kgf and a pressurization time of 2 minutes. . Measure the long and short axes of the glossy part of the molded disc to the nearest 1 mm with a dimension measuring device, calculate the average value, and use it as the elongation (mm) of the sample. In addition, the disk flow characteristic of the melamine-based resin molding composition for low-temperature/low-pressure molding of the present invention is preferably 100 to 120 mm, and if it is less than 100 mm, the flow will be insufficient, so it will not be possible to transfer it to the mold. This is undesirable because it tends to be insufficiently filled, and if it exceeds 120 mm, it tends to cause "sink marks" due to excessive flow, which is undesirable. (2) Test of minimum molding pressure characteristics Using the moldability test mold shown in Sections 5 and 4 of JIS K6911, mold temperature 150℃/150℃, mold clamping time 15 seconds, no preheating, Find the minimum molding pressure without degassing. The minimum molding pressure is the lowest pressure that does not cause scratches or cracks on the molded product, especially at the edges, and is determined by repeating molding several times by changing the pressure in 5 kg/cm ² units. (3) Mold releasability test A 9-inch flat plate with a wall thickness of approximately 3 mm was heated to a mold temperature of 160.
After putting the melamine resin molding composition into the mold at ℃/150℃, the mold was closed and the molding pressure was increased.
After reaching 100Kg/ ^cm2 , pressurize for a certain period of time. When the mold is opened, if the semi-cured molded product does not separate from the upper mold, but a part of it adheres to the upper mold and is separated into upper and lower parts, it is evaluated that the mold has not been released.
The mold releasability is improved by shortening the pressurization time in units of 1 second.
The minimum time for a semi-cured molded product of a melamine resin molding composition to remain in the lower mold without separating into the upper and lower molds is determined. (4) Cracking resistance test A bowl with a diameter of 6 inches and a weight of 120 g is compression molded under the following conditions. Mold temperature 160℃ (upper mold) 160℃ (lower mold) Pressure 180Kg/cm ² Preheating time 60 seconds Degassing time 0.5 seconds Molding time 120 seconds The bowl molded in this way was processed for the next cycle.
Perform four cycles a day, and calculate the number of cycles and days until a crack occurs.

[Table] (3) Check for the presence of cracks The crack resistance display is expressed as (number of days) - (number of cycles). For example, if it reads 2-3, a crack will occur on the third cycle on the second day. shows. The crack resistance is preferably 3-1 or higher, particularly preferably 4-1 or higher. (5) Heat resistance test Conducted in accordance with the "Appearance after heating" test in Section 5.23 of JIS K6911. The melamine resin molding composition is heated to the mold temperature.
A disk with a diameter of 50 ± 1 mm and a thickness of 3 ± 0.2 mm is molded at 160°C/160°C for 3 minutes without preheating. The test piece thus obtained is hung near a thermometer in a constant temperature bath kept at a constant temperature, and after 2 hours it is taken out and examined to see if there are any significant changes in appearance, such as cracks or blisters. The above test is conducted at different temperatures, and the highest temperature within the range where no significant change in appearance occurs is taken as the heat resistance value. Example 1 Melamine (manufactured by Yuka Melamine Co., Ltd.: Yuka Melamine)
1260 g (10 moles), 1379 g (approximately 17 moles) of a 37% by weight aqueous formalin solution, and 900 g of water were placed in a flask equipped with a reflux condenser, and a reaction was carried out by heating at 90° C. with stirring under the condition of F/M = 1.7. When the cloudy point of 20 volume % DMSO of the melamine resin liquid reached 21°C, 0.8 g of NaOH was added and cooled to obtain a melamine resin condensate. The cloudiness point of 20% DMSO by volume of the melamine resin solution used to measure the end of this reaction is:
Collect 5 ml of resin liquid and add it to 20% by volume at approximately 80℃.
This is the temperature at which cloudiness occurs when adding 45 ml of DMSO, stirring, and cooling. The melamine resin liquid thus obtained (solid content approx.
50% by weight), 600g of pulp (approximately 43 parts by weight per 100 parts by weight of the solid content of the melamine resin), and 7 g of polyethylene glycol (0.5 parts by weight per 100 parts by weight of the solid content of the melamine resin). After kneading in a kneader, the mixture was dried in a hot air dryer at 80°C for 90 minutes to obtain a raw material for melamine resin molding (popcorn). To 500 g of this raw material for melamine resin molding, 2 g of zinc stearate (manufactured by Kosei Co., Ltd., trade name "Zinc Stearate") (approximately 0.6 parts by weight per 100 parts by weight of the solid content of the melamine resin) was added, and 0.7 g of phthalic anhydride and 5 g of titanium oxide were added and pulverized in a pot mill for 8 hours to obtain a melamine resin molding composition. 20% by volume of the melamine resin molding composition
The cloudiness point using a DMSO aqueous solution was 70°C. The thus obtained melamine resin molding composition,
Furthermore, using a cold roll compressor, the cold roll compression conditions were a roll with a diameter of 250 mm and a width of 200 mm, a supply rate of 300 Kg/hr, a roll rotation speed of 20 rpm, and a roll pressurization pump pressure of 150 Kg/cm ² . The roll clearance is set to 0.5 mm, and the cold roll compression molded product is first made into a cold roll compression molded product, and then the cold roll compression molded product is roughly crushed and crushed using an impact crusher with a screen diameter of 2 mmφ to obtain a melamine resin molding composition. was granulated. In addition, the particle size of the granulated product of the melamine resin molding composition is
More than 85% by weight of the material passed through a 10-mesh JIS sieve and did not pass through a 100-mesh sieve. Using the above composition, physical property tests were conducted according to the test methods (1) to (5) above. The test results are shown in Table 1. These results show that the melamine resin molding composition of Example 1 has appropriate disk flow characteristics and appropriate minimum molding pressure characteristics, as well as excellent bleed-out prevention properties and excellent mold release properties. It had type characteristics. Furthermore, the melamine-based molded product obtained from the above composition had excellent crack resistance and heat resistance. Examples 2 to 6 and Comparative Examples 1 to 7 Using the melamine resin liquid of Example 1, a melamine resin molding composition was prepared as follows, and granulated in the same manner as in Example 1. Ta. Change the amount of PEG with an average molecular weight of 5500.
(Examples 2 to 4, Comparative Examples 1 and 2)
Use PEG. (Comparative Examples 3 and 4) The amount of pulp blended is changed. Example 5 and Comparative Example 5 The amount of zinc stearate is changed. Example 6, Comparative Examples 6 and 7 Next, the particles were granulated in the same manner as in Example 1, and the physical property tests were conducted in the same manner as in Example 1. Table 1 shows the components and test results of the obtained melamine resin molding composition. Comparative Examples 8 and 9 In Example 1, melamine resin liquids having different white turbidity points were prepared, and granulated melamine resin molding compositions were obtained in the same manner as in Example 1. For resins with low cloudiness points, water was used to measure the cloudiness points, and the cloudiness points were converted to the cloudiness points of a 20% by volume DMSO aqueous solution using a conversion table. Reference example 1 Production method of urea/formaldehyde resin Urea (manufactured by Nissan Chemical Industries, Ltd.) 600g (10 moles)37
Put 1176 g (approximately 14.5 moles) of formalin aqueous solution at a concentration of % by weight into a separable flask, and F/U = 1.45.
After reacting at 60℃ for 100 minutes under the following conditions, 10%
Add 1.4 ml of NH ₄ Cl aqueous solution, stir for 10 minutes, lower the water bath temperature to 50°C, and stir and react for an additional 20 minutes. 1000g of the urea resin liquid obtained in this way (solid content approx.
58% by weight) and 184g of pulp (solid content of urea resin 100%).
After adding about 32 parts by weight) and kneading in a kneader, the mixture was dried in a hot air dryer at 90°C for 120 minutes to obtain popcorn. Example 7 In Example 1, about 5500
Popcorn obtained in Reference Example 1 was added to 375 g of popcorn obtained in the same manner except that 10 g of PEG was used.
In addition, 5 g of titanium oxide, 0.5 g of phthalic anhydride, and 2 g of zinc stearate were added, and the mixture was ground in a pot mill for 8 hours to obtain a powder of a melamine resin molding composition. The cloudiness point of the melamine resin molding composition powder using a 20% by volume DMSO aqueous solution is:
It was 70℃. Example 1
The melamine resin molding composition obtained was granulated in the same manner as in Example 1, and the physical properties were tested in the same manner as in Example 1. Table 1 shows the components and test results of the above melamine resin molding composition. Example 8 375 g of popcorn obtained in the same manner as in Example 1 except that 20 g of about 5500 PEG was used.
Add 125g of popcorn obtained in Reference Example 1 to
Thereafter, a granulated product of a melamine resin molding composition was prepared in the same manner as in Example 7, and a physical property test was conducted.
Table 1 shows the components and test results of the above melamine resin molding composition. Examples 9 and 10, Comparative Examples 10 and 11 Popcorn 375 obtained in the same manner as in Example 1 except that the amount of PEG used was changed from about 5500.
g, add 125 g of popcorn obtained in Reference Example 1,
Thereafter, a granulated product of a melamine resin molding composition was prepared in the same manner as in Example 7, and a physical property test was conducted. Table 1 shows the components and test results of the above melamine resin molding composition. Comparative Examples 12 and 13 Melamine-based resin molding compositions were prepared in the same manner as in Example 8, except that a different PEG was used, and physical property tests were conducted in the same manner. The components and test results of the above molding composition are shown in Table 1. Example 11 Melamine (Yuka Melamine Co., Ltd.: Yuka Melamine)
1260g (10mol), urea (manufactured by Nissan Chemical Industries, Ltd.) 300
g (5 mol), 37% by weight formalin aqueous solution
1950g (approximately 24 moles) and 624g of water were placed in a separable flask, reacted at 80℃ for 60 minutes, and IN-
About 20 ml of NaOH was added and cooled to obtain a melamine resin condensate with a solid content of about 55% by weight. Pulp is added to 1000 g of the resin condensate thus obtained.
After adding 237 g (approximately 43 parts by weight to 100 parts by weight of melamine resin solid content) and 5.5 g of PEG of approximately 5500 (1 part by weight to 100 parts by weight of memin resin solid content) and kneading with a kneader, this The mixture was dried in a hot air dryer at 90°C for 90 minutes to obtain popcorn. 5 g of titanium oxide, 0.5 g of phthalic anhydride, and 2.5 g of zinc stearate were added to 500 g of this popcorn and ground in a pot mill for 8 hours to obtain a powder of a melamine resin molding composition. The cloudiness point of the above melamine resin molding composition using a 20% by volume DMSO aqueous solution was 60°C. Next, the above molding powder was granulated in the same manner as in Example 1, and physical property tests were conducted in the same manner as in Example 1 using the obtained melamine resin molding composition. The test results are shown in Table 1. Examples 12 and 13 Using the popcorn obtained in Example 8 and the popcorn obtained in Reference Example 1, a melamine resin molding composition was prepared in the same manner as in Example 8 except that the mixing ratio was changed. , similarly conducted physical property tests. The components and test results of the above molding composition are shown in Table 1. Example 14 449g of popcorn and 51g of urea obtained in Example 8
A melamine-based resin molding composition was prepared in the same manner as in Example 7 except that the following was used, and physical property tests were conducted in the same manner. Table 1 shows the components and test results of the obtained melamine resin molding composition. Example 15 and Comparative Example 14 A melamine-based resin molding composition was prepared in the same manner as in Example 14, except that the popcorn and urea obtained in Example 8 were used at different blending ratios, and the physical properties were tested in the same manner. I did this. Table 1 shows the components and test results of the obtained melamine resin molding composition.

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Claims (1)

[Scope of Claims] 1 () The following (a) and (b) (a) melamine/formaldehyde resin, and (b) the above (a) melamine/formaldehyde resin, (a) urea/formaldehyde resin, as well as/
or (b) 100 parts by weight of a melamine resin selected from the group consisting of mixed resins consisting of ureas, () 0.4 to 3 parts by weight of polyethylene glycol with an average molecular weight of 2,000 to 10,000, and () 25 to 65 parts by weight of pulp. A melamine resin molding composition comprising: A melamine-based resin molding composition characterized by a temperature of 14 to 93°C.