JP2000080247A - Thermosetting resin composition, and thermosetting resin molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of remarkably controlling the generation of formaldehyde and useful for producing molds, etc., by including a thermosetting resin with a specific compound. SOLUTION: This thermosetting resin composition is obtained by including (A) a thermosetting resin containing formaldehyde (preferably a phenolic resin, a urea resin, a melamine resin, etc.), with (B) at least one compound selected from a compound of formula I [X is O or S; R1-R4 are each H, a 1-8C (substituted) alkyl, a 3-8C (substituted) cycloalkyl or the like] and a compound of formula II [R5-R9 are each H, a 1-8C (substituted) alkyl, a 3-8C (substituted) cycloalkyl or the like] (for example, hydrazodicarbonamide) in an amount of 0.1-10 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermosetting resin composition containing formaldehyde and a thermosetting resin molded article.

[0002]

2. Description of the Related Art As a thermosetting resin containing formaldehyde, for example,
Phenolic resins such as phenolic resins and xylene resins,
Various resin containing formaldehyde such as amino resin such as melamine resin and urea resin, furan resin having furan ring, butanol-modified urea resin containing formaldehyde and modified alkyd resin containing formaldehyde and urethane resin containing formaldehyde as resin components Modified resins and the like are known.

[0003] These thermosetting resin compositions are generally cured by applying heat or the like, and become infusible and insoluble resins.
Since it contains formaldehyde, it has the following problems.

[0004] That is, unreacted formaldehyde in the resin raw material is liberated and generated, or once cured resin (or / and curing agent) is decomposed by heat or the like, formaldehyde is generated, and the working environment is significantly deteriorated. There was a problem to make it.

[0005] For example, in the casting industry, when molds such as molds and cores are manufactured, a mold aggregate such as silica sand is coated with a thermosetting resin binder such as phenol resin. A shell-type method for producing molds using the obtained resin-coated sand has been performed.

When molds are produced by such a shell type method, unreacted free formaldehyde is generated,
Alternatively, by applying resin-coated sand to a heated mold model, hexamethylenetetramine as a curing agent is decomposed to generate free formaldehyde.

Further, when a molten metal is poured into the molds after the molds are manufactured, the phenol resin is decomposed by the heat of the molten metal to generate free formaldehyde. As described above, since the generation of formaldehyde is remarkable in the molds, improvement of the working environment is particularly desired.

Therefore, conventionally, in the condensation reaction of formaldehyde and phenol, means has been adopted in which formaldehyde is reacted as much as possible to polymerize it to suppress the generation of free formaldehyde. Not only is the effect not obtained, but also formaldehyde that can be generated after curing the resin cannot be suppressed.

Further, for example, a method of trapping free formaldehyde with ammonia or the like has been adopted (see Japanese Patent Publication No. 7-25990). However, closed facilities must be newly provided, and the ammonia itself has to be prepared. Is also a harmful substance, so it is preferable not to use it.

Certain hydrazo compounds are known as foaming agents (Plastic Form Handbook, edited by Atsushi Makihiro and Atsushi Kosakada, February 28, 1973, published by Nikkan Kogyo Shimbun, p. 93, p. 96). A material obtained by blending these with a curable resin and foaming them is also known (JP-A-4-81435), but the hydrazo compound is decomposed into nitrogen gas or the like when thermally decomposed, so In addition, no hydrazo compound remains in the composition, and formaldehyde cannot be supplemented.

Furthermore, Japanese Patent Application Laid-Open No. 52-5872 discloses that a casein plastics is treated with a treating solution selected from ureas to reduce the amount of eluted formaldehyde. A technique using an amide is disclosed, and formaldehyde present near the surface of casein plastics can be removed by washing casein plastics with a treatment solution selected from ureas. However, since the above-mentioned technology does not include urea in the resin composition, there is no disclosure or suggestion about suppressing formaldehyde generated by decomposition of the resin in a high-temperature environment, It is not disclosed at all whether the ureas have an excellent formaldehyde-suppressing effect under a high-temperature environment.

[0012] In view of the above, it is an object of the present invention to provide a thermosetting resin composition and a thermosetting resin molded product that can significantly suppress the generation of formaldehyde.

[0013]

As a means for solving the above-mentioned problems of the present invention, a hydrazo compound represented by the following general formula (1) or (2) is a thermosetting resin composition containing formaldehyde. The present invention relates to a thermosetting resin composition containing 0.1 to 10 parts by weight of at least one selected from the group consisting of: Further, the present invention provides a thermosetting resin composition wherein the thermosetting resin is at least one selected from phenolic resins, urea resins, melamine resins, xylene resins, toluene resins, furan resins, and butanol-modified urea resins. Related. Furthermore, the present invention relates to a thermosetting resin molded article obtained by heating and curing the thermosetting resin composition at a temperature not higher than the decomposition temperature of the hydrazo compound.

Since the thermosetting resin composition according to the present invention contains the above-mentioned hydrazo compound, it is considered that the hydrazo compound adsorbs and deodorizes free formaldehyde, and the action significantly suppresses the generation of formaldehyde. Can be. In addition, the hydrazo compound can significantly suppress the generation of formaldehyde even in a relatively high temperature range.

Further, since the molded article according to the present invention is molded by heating and curing at a temperature not higher than the decomposition temperature of the hydrazo compound, the generation of formaldehyde during and after molding can be achieved without losing the effect of the hydrazo compound. Can be significantly suppressed.

Incidentally, Japanese Patent Application Laid-Open No. 1-158081 discloses that
A conductive coating composition in which a certain hydrazo compound is compounded together with copper powder in a binder resin for coating is disclosed. In this publication, the general formula (1) used in the present invention is disclosed.
Or, the hydrazo compound represented by (2) is not disclosed.

In the present invention, the thermosetting resin composition containing formaldehyde includes phenolic resins, urea resins, melamine resins, xylene resins, toluene resins, furan resins, butanol-modified urea resins, and various other formsaldehyde-containing urea resins. Refers to a thermosetting resin composition in which formaldehyde is used as a resin material such as a modified resin,
Even if formaldehyde is not directly used as a resin raw material, a thermosetting resin composition to which a curing agent or the like capable of decomposing to form formaldehyde is added is also included.

The hydrazo compound of the present invention is represented by the following general formula (1) or (2).

[0019]

Embedded image

Wherein X is oxygen or sulfur, R₁,
R_Two, R_ThreeAnd R_FourAre the same or different groups, and
Elementary, C₁~ C₈Alkyl, C₁~ C₈Substituted alkyl, C_Three~
C₈Cycloalkyl, C_Three~ C₈Substituted cycloalkyl,
Phenyl, substituted phenyl, aryl C ₁~ C_FourAlkyl, also
Is a substituted aryl C₁~ C_FourAlkyl group (substituted alkyl
And the like, for example, halogen, C₁~ C_FourAl
Kill, C₁~ C_FourAlkoxy, amino (-NH_Two), Nito
B (-NO_Two) Groups and the like are exemplified). Also, R₁When
R_TwoAnd / or R_ThreeAnd R_FourTogether form a ring
Good. ]

[0021]

Embedded image

[Wherein R_Five, R₆, R₈And R₉Are the same
Or different groups, hydrogen, C₁~ C₈Alkyl, C₁
~ C₈Substituted alkyl, C_Three~ C₈Cycloalkyl, C_Three~ C
₈Substituted cycloalkyl, phenyl, substituted phenyl, ant
C₁~ C_FourAlkyl, substituted aryl C₁~ C_FourArchi
Or carboxy C₁~ C_FourAlkyl group (substituted alkyl
Examples of substituents such as kill include halogen, C₁~ C_Four
Alkyl, C₁~ C_FourAlkoxy, amino (-NH_Two),
Nitro (-NO_Two) Groups). ₇Is
Cyano (-CN) or -COOR_TenRepresents a group (note that R_Ten
Is hydrogen or C₁~ C_FourRepresents an alkyl group). Also, R_Five
And R₆And / or R₈And R₉Together form a ring
Is also good. ]

Among the compounds represented by the general formula (1), specific examples which can be preferably used in the present invention include, for example, X is oxygen, and R ₁ , R ₂ , R ₃ and R ₄ are Examples thereof include hydrazodicarbonamide which is all hydrogen.

Further, a compound represented by the above general formula (2)
Among them, tools that can be preferably used in the present invention
As a body example, for example, R_Five, R₆, R₈And R₉Is methyl
Group, R₇Is a cyano group, 2,2'-hydrazobisiso
Butyronitrile, R5 and R₈Is a methyl group, R₆And R₉
Is an ethyl group, R₇Is a cyano group, 2,2′-hydrazo
Bis-2-methylbutyronitrile, R_FiveAnd R₈Is methyl
Group, R₆And R₉Is an isobutyl group, R₇Is a cyano group
2,2'-hydrazobis-2,4-dimethylvaleronito
Lil, R_FiveAnd R₆And R₈And R₉Forms a cyclohexane ring
Then R₇Is a cyano group, 1,1'-hydrazobis-1
-Cyclohexanecarbonitrile, R_FiveAnd R₈Is methyl
Group, R₆And R₉Is a carboxyethyl group, R₇Is a cyano group
4,4'-hydrazobis-4-cyanovaleric acid, R
_Five, R₆, R₈And R₉Is a methyl group, R ₇Is methoxycarbo
Dimethyl-2,2'-hydrazobisisobu
Chillates are exemplified.

In addition, in the present invention, the compound represented by the above general formula (2) is disclosed in JP-B-56-39322.
Hydrazo compounds described in JP-B-57-35867 and JP-B-57-35867 can also be used.

One of the above hydrazo compounds may be used alone, or two or more may be selected and used.

As the resin raw material, those conventionally used depending on the type of the resin are used. For example, phenol and formaldehyde are used for a phenol resin, and butanol, formaldehyde and urea are used for a butanol-modified urea resin.

The amount of the hydrazo compound to be mixed may be appropriately selected according to the type of the hydrazo compound, the type of the resin raw material, and the like. Usually, it is preferably about 0.1 to 10% by weight based on the total amount of the resin. About 5% by weight is more preferable. If too much hydrazo compound is mixed, the properties of the cured resin are affected, while if too little hydrazo compound is used, the effect of suppressing formaldehyde cannot be expected.

The hydrazo compound and the resin raw material can be mixed by a usual mixing means to produce the thermosetting resin composition according to the present invention.

The thermosetting resin composition according to the present invention is used not only for producing molds (resin composition of resin-coated sand for molds) but also for general resin molded articles, paints, adhesives and the like. It can be used for various applications depending on the resin raw material.

Further, the thermosetting resin composition according to the present invention can be formed into a molded article by a known molding means such as compression molding and injection molding, and in this case, the generation of formaldehyde is sufficiently suppressed. In order to obtain a compact that can be
It is preferable to heat and cure at a temperature not higher than the decomposition temperature of the hydrazo compound and to mold.

The thermosetting resin composition according to the present invention may contain, for example, a modifier,
Various additives such as a crosslinking agent, a bactericide, a fungicide, an insect repellent, a pigment, a colorant, and a fragrance may be mixed.

[0033]

The present invention will be described more specifically with reference to examples and comparative examples of the present invention.

Example 1 100 g of solid novolak resin (trade name: SP700NS, manufactured by Asahi Organic Materials Industry Co., Ltd.) and hydrazodicarbonamide (Otsuka Chemical Co., Ltd.) were used as resin materials in 5 kg of weathered silica sand preheated to 150 ° C. Was added to a speed mixer manufactured by Enshu Tekko Co., Ltd., and the mixture was stirred and mixed for 30 seconds, mixed well, and melt-coated.

Next, 75 g of hexamethylenetetramine (reagent) and 75 g of cooled deionized water were added thereto.
Further, the mixture was stirred and mixed for 40 seconds while being rapidly cooled by blowing, then 5 g of calcium stearate was added, and the mixture was further stirred and mixed for 15 seconds. The sand particles thus obtained were loosened and taken out to obtain resin-coated sand.

[0036] except that no addition of hydrazodicarbonamide the resin material In Comparative Example 1 Example 1, the same operation as in Example 1 to obtain a resin-coated sand according to Comparative Example 1.

Formaldehyde Quantitative Test In a sealable box (60 mm long × 120 mm wide × 170 mm high) placed on an iron plate heated to 250 ° C.
2.5 g of the resin-coated sand of Example 1 was charged, baked for 70 g seconds, and immediately after that, the formaldehyde gas concentration in the box was measured with a Kitagawa detector tube (measurement range: 1 to 35 ppm).

Similarly, the resin-coated sand 2.5 of Comparative Example 1
g was measured for formaldehyde gas concentration.

Table 1 shows the results.

[0040]

[Table 1]

In the resin-coated sand of Example 1, only 1 ppm of formaldehyde was detected, and almost no formaldehyde was generated as compared with Comparative Example 1 (30 ppm detected).
This is probably because the hydrazodicarbonamide contained in the resin adsorbed formaldehyde. Further, it was confirmed that the resin-coated sand of Example 1 was able to significantly suppress the generation of formaldehyde even in a relatively high temperature range of 250 ° C.

Example 2 5 parts by weight of hydrazodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) was added to 95 parts by weight of urea resin as a resin raw material, and the mixture was sufficiently mixed using a blender. At 150 ° C. and a molding pressure of 180 kg / cm ² ), a plate-like molded body was obtained. Example 3 As a resin raw material, 5 parts by weight of hydrazodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) was added to 95 parts by weight of a melamine resin,
After sufficiently mixing using a blender, compression molding (mold temperature: 160 ° C., molding pressure: 130 kg / cm ² ) was performed to obtain a plate-like molded body. Example 4 As a resin raw material, 5 parts by weight of hydrazodicarbonamide (manufactured by Otsuka Chemical Co., Ltd.) was added to 95 parts by weight of a phenol resin, mixed well using a blender, and then compression molded (a mold temperature of 160 ° C., Molding pressure 180 kg / cm ² )
Thus, a plate-like molded body was obtained.

Comparative Example 2 Comparative Example 2 was carried out in the same manner as in Example 2 except that 5 parts by weight of urea was used instead of hydrazodicarbonamide.
Was obtained. Comparative Example 3 A molded product according to Comparative Example 3 was obtained in the same manner as in Example 2 except that hydrazodicarbonamide was not added to the resin raw material. Comparative Example 4 Comparative Example 4 was carried out in the same manner as in Example 3 except that 5 parts by weight of urea was added instead of hydrazodicarbonamide.
Was obtained. Comparative Example 5 The same operation as in Example 3 was performed except that hydrazodicarbonamide was not added to the resin raw material, to obtain a molded body according to Comparative Example 5. Comparative Example 6 Comparative Example 4 was carried out in the same manner as in Example 4 except that 5 parts by weight of urea was added instead of hydrazodicarbonamide.
Was obtained. Comparative Example 7 The same operation as in Example 4 was performed except that hydrazodicarbonamide was not added to the resin raw material, to obtain a molded body according to Comparative Example 5.

Sensory test of formaldehyde When the molded articles of Examples 2 to 4 and Comparative Examples 2 to 7 were compression-molded, the odor of formaldehyde around the molding machine was compared. On the other hand, in each of Comparative Examples 2 to 7, a slight formaldehyde odor was felt.

Quantitative test of formaldehyde A sealable box (60 mm long × 120 mm wide × 170 m high) placed on an iron plate heated to 80 ° C. or 150 ° C.
m), 2.5 g of each of the crushed products of the molded products obtained in Examples 2 to 4 and Comparative Examples 2 to 7 were placed and sealed. After 10 minutes, the formaldehyde concentration in the box was measured using a Kitagawa type detection tube (measurement range). 1-35
ppm). The results are shown in Tables 2 and 3.

[0046]

[Table 2]

[Table 3]

In the molded products of Examples 2 to 4, only 2 ppm of formaldehyde was detected, and almost no formaldehyde was detected as compared with Comparative Examples 2 to 7. This is probably because the hydrazodicarbonamide contained in the resin effectively adsorbed formaldehyde.

[0048]

The thermosetting resin composition according to the present invention can be used either when the composition is cured or after the composition is cured.
Generation of formaldehyde can be effectively suppressed. Therefore, the use of the thermosetting resin composition according to the present invention can easily improve the working environment. Further, the thermosetting resin composition according to the present invention can remarkably suppress the generation of formaldehyde even in a high temperature range, and thus can be particularly suitably used as a resin composition for coating resin-coated sand for a mold.

Claims (3)

[Claims] 1. A thermosetting tree containing formaldehyde.
Hydra represented by the following general formula (1) or (2)
At least one compound selected from the group consisting of
A thermosetting resin composition, characterized in that the thermosetting resin composition contains at least one part by weight. Embedded imageWherein X is oxygen or sulfur, R₁, R_Two, R_ThreeAnd R_Four
Are the same or different groups and are hydrogen, C₁~ C₈Al
Kill, C₁~ C₈Substituted alkyl, C_Three~ C₈Cycloalkyl
Le, C_Three~ C₈Substituted cycloalkyl, phenyl, substituted phenyl
Nil, aryl C ₁~ C_FourAlkyl or substituted aryl C
₁~ C_FourAlkyl group (as a substituent such as substituted alkyl, etc.)
Is, for example, halogen, C₁~ C_FourAlkyl, C₁~ C_FourA
Lucoxy, amino (-NH_Two), Nitro (-NO_Two) Group
Is exemplified). Also, R₁And R_TwoAnd / or R_Three
And R_FourAnd may together form a ring. ][Wherein, R_Five, R₆, R₈And R₉Are the same or different groups
And hydrogen, C₁~ C₈Alkyl, C₁~ C₈Substitution al
Kill, C_Three~ C₈Cycloalkyl, C_Three~ C₈Substituted cycloa
Alkyl, phenyl, substituted phenyl, aryl C₁~ C_FourA
Alkyl, substituted aryl C₁~ C_FourAlkyl or carboxy
C₁~ C_FourAlkyl group (in addition, substituent such as substituted alkyl
For example, halogen, C₁~ C_FourAlkyl, C₁~
C_FourAlkoxy, amino (-NH_Two), Nitro (-N
O_Two) Groups). ₇Is cyano (-C
N) or -COOR_TenRepresents a group (note that R_TenIs hydrogen or
C₁~ C_FourRepresents an alkyl group). Also, R_FiveAnd R₆And / or
Is R₈And R₉And may together form a ring. ] 2. The thermosetting resin is a phenol resin, a urea resin, a melamine resin, a xylene resin, a toluene resin,
The thermosetting resin composition according to claim 1, which is at least one selected from a furan resin and a butanol-modified urea resin. 3. A thermosetting resin molded product obtained by heating and curing the thermosetting resin composition according to claim 1 at a temperature not higher than the decomposition temperature of the hydrazo compound.