JP3121795B2 - Thermosetting resin composition for resin coated sand for mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting resin composition for forming resin-coated sand containing formaldehyde.

[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.

[0010] The present invention has been made in view of the problems described above, during molding and forming
It is an object of the present invention to provide a thermosetting resin composition for a resin-coated sand for a mold, which can significantly suppress the generation of formaldehyde after shaping .

[0011]

As a means for solving the above-mentioned problems of the present invention, a thermosetting resin containing formaldehyde is added to a compound represented by the following general formula (1) or (2).
At least one selected from the product, based on the total amount of the resin
Mold tree made by mixing 0.1% by weight to 10% by weight as
The present invention relates to a thermosetting resin composition for fat-coated sand.

The thermosetting resin composition for resin-coated sand according to the present invention is represented by the following general formula (1) or (2).
Compound (herein referred to as "hydrazo compound")
Because if contains a is) considered the hydrazo compound adsorbs deodorant free formaldehyde, can be remarkably suppressed the generation of formaldehyde by for the acting. In addition, the hydrazo compound can significantly suppress the generation of formaldehyde even in a relatively high temperature range.

In the present invention, a thermosetting resin composition containing formaldehyde refers to a thermosetting resin in which formaldehyde is used as a resin material such as a phenolic resin, an amino resin, a furan resin, and other various modified resins including formaldehyde. Resin composition, and also includes a thermosetting resin composition to which a curing agent capable of decomposing to generate formaldehyde is added even if formaldehyde is not directly used as a resin raw material. It is.

[0014]

The compound represented by the general formula (1) or (2) is as follows.

[0016]

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. ]

[0018]

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 the substituent 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 above 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.

Among the compounds represented by the above general formula (2), specific examples which can be preferably used in the present invention include, for example, those in which R ₅ , R ₆ , R ₈ and R ₉ are methyl groups. , 2,2' Hydra azobisisobutyronitrile R ₇ is a cyano group, R ₅ and R ₈ are methyl, R ₆ and R ₉ are ethyl, 2, 2 R ₇ is a cyano group ' -Hydrazobis-
2-methylbutyronitrile, R ₅ and R ₈ are methyl groups, R
2,2 ′ wherein ₆ and R ₉ are isobutyl groups and R ₇ is a cyano group
Hydrazobis-2,4-dimethylvaleronitrile, R
₅ and R ₆ and R ₈ and R ₉ form a cyclohexane ring, R ₇
Is a cyano group, 1,1′-hydrazobis-1-cyclohexanecarbonitrile, R ₅ and R ₈ are methyl groups, R ₆
And R ₉ is carboxyethyl group, R ₇ is a cyano group 4,4' Hidorazobisu 4-cyanovaleric acid, R _5,
Examples include dimethyl-2,2'-hydrazobisisobutyrate wherein R ₆ , R ₈ and R ₉ are methyl groups and R ₇ is a methoxycarbonyl group.

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.

The above hydrazo compounds may be used alone or in a combination of two or more.

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 in 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 ordinary mixing means to produce the thermosetting resin composition according to the present invention.

The thermosetting resin composition according to the present invention is used for producing molds (resin composition of resin-coated sand for molds).
You.

The thermosetting resin composition for a resin-coated sand for a mold according to the present invention is provided in such a range that the effect is not impaired.
For example, various additives such as a modifying agent, a crosslinking agent, a bactericide, a fungicide, an insect repellent, a pigment, a colorant, and a fragrance may be mixed.

[0029]

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

Example 5 100 g of solid novolak resin (trade name: SP700NS, manufactured by Asahi Organic Materials Industry Co., Ltd.) and hydrazodicarbonamide (manufactured by 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 to mix well and melt coat.

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.

Comparative Example The same operation as in the above example was carried out except that no hydrazodicarbonamide was added to the resin raw material in the above example.
Resin-coated sand according to a comparative example was obtained.

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 the above example was charged and baked for 70 g, 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, 2.5 g of resin-coated sand of the comparative example
Was measured for formaldehyde gas concentration.

Table 1 shows the results.

[0036]

[Table 1]

In the resin-coated sand of Example, only 1 ppm of formaldehyde was detected, and Comparative Example (30 ppm detection)
Almost no formaldehyde was generated. This is because hydrazodicarbonamide contained in the resin,
This is probably because formaldehyde was adsorbed. Also,
It was confirmed that the resin-coated sand of the example can significantly suppress the generation of formaldehyde even in a relatively high temperature range of 250 ° C.

[0038]

The thermosetting resin composition for a resin-coated sand for a mold according to the present invention is represented by the general formula (1) or (2).
By mixing at least one selected from the compounds
Significantly reduces formaldehyde emission even at high temperatures.
Since the composition can be suppressed , the generation of formaldehyde can be effectively suppressed both when the composition is cured and after the composition is cured. Thus , this composition is
Manufactures molds using resin-coated sand for molds coated on materials
Then, the working environment is improved.

Continuation of the front page (56) References JP-A-52-5872 (JP, A) JP-A-1-197410 (JP, A) JP-A-4-81435 (JP, A) JP-A-1-158081 (JP) JP-A-55-130714 (JP, A) JP-A-49-106558 (JP, A) JP-A-10-36524 (JP, A) JP-A-10-245794 (JP, A) 3-94952 (JP, A) JP-A-62-285945 (JP, A) Makihiro, Atsushi Kosakada “Plastic Form Handbook”, edited by Nikkan Kogyo Shimbun, p. 93 p. 96 (58) Field surveyed (Int.Cl. ⁷ , DB name) B22C 1/00-1/26 C08L 61/00-61/34 C08G 8/00-8/38 C08G 12/00-12/46 CA (STN) REGISTRY (STN)

Claims (1)

(57) [Claims] A thermosetting resin containing formaldehyde comprises a compound represented by the following general formula (1) or (2):
At least one selected based on the total amount of the resin.
A thermosetting resin composition for a resin-coated sand for a mold , characterized in that the composition is mixed with 0.1% by weight to 10% by weight . Embedded image [Wherein, X represents oxygen or sulfur, R ₁ , R ₂ , R ₃ and R ₄
Is the same or different groups selected from hydrogen, C ₁ -C ₈ al
Killed , C ₁ -C ₈ substituted alkyl, C ₃ -C ₈ cycloalkyl
Le, C ₃ -C ₈ substituted cycloalkyl, phenyl, substituted Fe
Nyl, aryl C ₁ -C ₄ alkyl, or substituted aryl C
₁ -C ₄ alkyl group (Note, as a substituent such as a substituted alkyl
Is, for example, halogen, C ₁ -C ₄ alkyl, C ₁ -C ₄ A
Alkoxy, amino (-NH _2), nitro (-NO ₂₎ group
Is exemplified). Also, R ₁ and R ₂ and / or R ₃
And R ₄ may together form a ring. ] [Formula 2] Wherein R ₅ , R ₆ , R ₈ and R ₉ are the same or different
Wherein hydrogen, C ₁ -C ₈ alkyl, C ₁ -C ₈ substituted alkyl
Kill, C ₃ -C ₈ cycloalkyl, C ₃ -C ₈ substituted Shikuroa
Alkyl, phenyl, substituted phenyl, aryl C ₁ -C ₄ A
Alkyl , substituted aryl C ₁ -C ₄ alkyl, or carboxyl
C ₁ -C ₄ alkyl groups (with substituents such as substituted alkyl, etc.)
Is then, for example, halogen, C ₁ -C ₄ alkyl, C ₁ ~
C ₄ alkoxy, amino (-NH _2), nitro (-N
O ₂₎ group and the like) indicates, R ₇ is cyano (-C
N) or —COOR ₁₀ group (where R ₁₀ is hydrogen or
Shows a C ₁ ~ C ₄ alkyl group). Also, R ₅ and R ₆ and / or
R ₈ and R ₉ may together form a ring. ]