JP2923303B2 - Melamine resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a melamine resin composition,
In particular, it relates to a resin composition comprising a melamine resin modified with a glycidyl compound.

(Prior art)

The molded product cured by heating and pressing the melamine resin composition is hard and durable, but it lacks flexibility, impact and bending deflection, weakens tensile elongation and causes cracks,
There was a problem of destruction. Amino compounds have been modified with glycidyl compounds so far, and the cross-linked structure of the melamine resin is formed by modification of the glycidyl compound with -CH = CH
-CH ₂ - is an attempt to solve the above problems by the soft segment made, has the considerable effect on impact, or cause weak crack deflection and tensile elongation of the bend, destroys The problem remained. For this reason, there are limitations on the applications of use, and screws and screws must be used for assembling and mounting these molded products, which has been a bottleneck in the number of parts in the assembling and mounting processes, and in automation. Therefore, a melamine resin composition that provides a thermosetting resin molded article to which a snap phyte commonly used for assembling and mounting a molded article resistant to bending deflection and tensile elongation made of a thermoplastic resin composition can be applied has been expected. .

[Problems to be Solved by the Invention] The present invention relates to a melamine resin composition which gives a melamine resin molded article which is strong in impact strength, bending deflection and tensile elongation in a molded article of the melamine resin composition, and which can be applied to snap fit. To provide things.

[Means for solving the problem]

The present inventor has studied various fillers using a resin modified with the glycidyl compound of the melamine resin in order to solve the above problems, and has reached the present invention. That is, the present invention comprises 100 parts by weight of a solid resin of a melamine resin modified with a glycidyl compound, 0.5 to 6 mm in fiber length, 5 to 70 parts by weight of an organic synthetic fiber having a fiber diameter of 3 to 5 denier, a curing agent, and a release agent. A melamine resin composition characterized by having the same. Hereinafter, the present invention will be described in detail.

Glycidyl compounds in the molecule A glycidyl compound in the present invention. Glycidyl ether compounds having a group are also included. Examples of preferred glycidyl compounds used in the present invention include ethylene glycol glycidyl ether,
Examples include polyethylene glycol diglycidyl ether, polypropylene glycol glycidyl ether, neopentyl glycol diglycidyl ether, 1,6 hexanediol glycidyl ether, and trimethylolpropane polyglycidyl ether.

Modification of the melamine resin with a glycidyl compound and solidification is performed as follows. First, in preparing a melamine resin modified with a glycidyl compound,
The reaction can be carried out by reacting the melamine resin with the glycidyl compound as the next reaction, and then reacting this reactant with formaldehyde as the secondary reaction. The primary reaction is considered to be a reaction in which the epoxy group of the glycidyl compound is ring-opened to the amino group of the melamine resin and dehydration-added. 2
The next reaction is considered to be caused by dehydration addition of formaldehyde to unreacted amino groups of the melamine resin. Here, the primary reaction is carried out at a temperature of about 80 to 100 ° C. for 10 to 150
It is preferable to carry out the reaction for about
It is desirable to set conditions so that the process is performed at a temperature of about 0 ° C. for about 5 to 90 minutes. The product obtained by such a reaction is in the form of a syrup, and the syrup can be used as a solid melamine resin modified with a glycidyl compound by dehydration. In the dehydration, it is preferable to use conditions under which the reaction for further polymerizing the resin proceeds. For this reason, dehydration is preferably a method involving heating, such as vacuum heating dehydration, spray dryer, WFE
(Thin film evaporation method) or the like can be used. In addition, the compounding amount of each component at the time of the reaction, the molar number of melamine is M, the molar number of the glycidyl compound is G, and the molar number of formaldehyde is F, the molar ratio of the glycidyl compound to the melamine resin is 0.01 ≦ G / M ≦ (number of amino groups of melamine ×
2) -0.2 The molar number of formaldehyde with respect to the difference between the molar number of the melamine resin and the glycidyl compound is 0.5 ≦ F / (M−
G) It is desirable to set the molar range so that ≦ (the number of amino groups of melamine) × 2 × 0.7. If the number of moles of the glycidyl compound relative to melamine is less than 0.01, the modification by the glycidyl compound is insufficient, and the effect of increasing the flexibility of the melamine resin and improving the toughness cannot be sufficiently obtained. If it exceeds (number of amino groups of melamine × 2) −0.2, the amount of glycidyl compound in the reaction system becomes too large, and it becomes easy to gel due to the action of amino groups. Similarly, the flexibility of melamine resin is enhanced to increase the toughness. Cannot be sufficiently obtained. Usually, the mole number M of melamine is set to be larger than the mole number G of the glycidyl compound. Further, if the number of moles of formaldehyde relative to the difference between the number of moles of melamine and the glycidyl compound is less than 0.5, the amount of formaldehyde is insufficient, the melamine resin cannot be sufficiently crosslinked and cured, and the molar ratio is (melamine If the number of amino groups in the resin exceeds 2 × 0.7, formaldehyde becomes excessive and the crosslink density of the melamine resin becomes too high, thereby increasing the flexibility of the melamine resin. Therefore, the effect of improving the toughness cannot be sufficiently obtained. The solid melamine resin modified with the dehydrated and dried glycidyl compound is crushed and mixed with a filler or other release agent or curing agent to prepare a molding material, and compression molding, transfer molding, injection molding, etc. Molded articles can be created.

As the above-mentioned filler, by using an organic synthetic fiber such as acrylic fiber polyester fiber for carbon fiber in a range of 5 to 70 parts by weight based on 100 parts by weight of the melamine resin, a molded product of such a resin molded product is obtained. The effect of improving the toughness can be obtained by increasing the flexibility. When the amount of the organic synthetic fiber is less than 5 parts by weight, the effect of improving the toughness by increasing the flexibility of a molded article of the resin composition cannot be obtained. Is reduced, and the moldability deteriorates, so that it is limited to this range. When an inorganic fiber filler such as glass fiber is used in combination, it is possible to obtain an effect of improving particularly rigidity such as bending strength and Charpy impact strength. Fiber length and fiber diameter of organic synthetic fiber are 0.5 ~ 6mm and 3 ~ 5 respectively.
Restriction to denier fibers prevents variation in characteristic values such as impact strength, bending strength, tensile strength and bending deflection, tensile elongation without damaging the appearance of the resulting molded article. This is because the resin composition is easily dispersed uniformly. As the curing agent and the release agent, those usually used can be applied as they are.

Next, the present invention will be specifically described with reference to Examples and Comparative Examples.

〔Example〕

Example 1 At a molar ratio of G / M = 0.12, F / (MG) = 1.6, melamine as M, polyethylene glycol glycidyl ether as G, and formaldehyde as F were mixed, and the first reaction was performed at 95 ° C. for 45 minutes. The secondary reaction was carried out at 85 ° C. for 35 minutes to obtain a melamine resin syrup modified with a glycidyl compound. This melamine resin syrup was put into a vacuum kneader, decompressed to 60 mmHg, and heated with steam at 200 ° C. to be dehydrated by heating under vacuum to obtain a solid melamine resin modified with a glycidyl compound. The molding material is 100 parts by weight of the modified solid melamine as a filler, a fiber length of 0.5 mm, a fiber diameter of 3 denier, 8 parts by weight of acrylic fiber for carbon fiber, a valve of 35 parts by weight, and a zinc stearate as a releasing agent. 0.8 parts by weight and 0.15 parts by weight of phthalic anhydride as a curing agent are added to a pot mill, and the mixture is rotated for 3 hours to prepare a powder.

Example 2 100 parts by weight of the modified solid melamine of Example 1 was used as a filler except that the fiber length was 2.5 mm, the fiber diameter was 3 parts, the acrylic fiber for carbon fiber was 18 parts by weight, and the valve was 25 parts by weight. A molding material was obtained in the same manner as in Example 1.

Example 3 100 parts by weight of the modified solid melamine of Example 1 was used as a filler, except that the fiber length was changed to 30 parts by weight of acrylic fiber for carbon fiber having a fiber length of 1.5 mm and a fiber diameter of 3 denier, and 13 parts by weight of pulp. A molding material was obtained in the same manner as in Example 1.

Example 4 Same as Example 1 except that the modified solid melamine of Example 1 was replaced with 100 parts by weight of the modified solid melamine as a filler and 43 parts by weight of acrylic fiber for carbon fiber having a fiber length of 3 mm and a fiber diameter of 3 denier. A molding material was obtained.

Example 5 Same as Example 1 except that the modified solid melamine of Example 1 was changed to 70 parts by weight of acrylic fiber for carbon fiber having a fiber length of 6 mm and a fiber diameter of 5 denier as a filler for 100 parts by weight of the modified solid melamine. A molding material was obtained.

Example 6 A molding material was obtained in the same manner as in Example 2 except that the pulp of Example 2 was changed to glass fiber.

Example 7 A molding material was obtained in the same manner as in Example 3 except that the pulp of Example 3 was changed to glass fiber.

Comparative Example 1 A molding material was obtained in the same manner as in Example 1 except that pulp was changed to 43 parts by weight as a filler with respect to 100 parts by weight of the modified solid melamine of Example 1.

In accordance with JIS K6911 using each molding material obtained above
A test piece was formed by molding at a mold temperature of 165 ° C. for 2 minutes using a 37-ton press molding machine. For this test piece, the bending strength, bending deflection,
The tensile strength was measured, and the tensile elongation was determined using silica as the ratio of the amount of change of the test piece at the time of measuring the tensile strength to the length of the original test piece. The results are shown in Table 1.

Using acrylic fiber for carbon fiber instead of pulp (Comparative Example 1) as a filler from Table 1, large bending deflection and tensile elongation characteristics without impairing the appearance while maintaining the bending strength and tensile strength. Could be confirmed. Further, in Examples 6 and 7, it was confirmed that high Charpy impact characteristics can be secured when glass fibers are used together.

〔The invention's effect〕

By using the resin composition of the present invention, it is possible to obtain a molded product that is strong in bending and tensile elongation while maintaining rigidity of impact strength.

Claims (1)

(57) [Claims] 1. A melamine resin-modified solid resin of 100 parts by weight, a fiber length of 0.5 to 6 mm, an organic synthetic fiber having a fiber diameter of 3 to 5 parts by weight of 5 to 70 parts by weight, a curing agent and a release agent. A melamine resin composition comprising: