JPH01126348A - Resin composition for expansion - Google Patents

Abstract

PURPOSE:To obtain the titled composition, containing a copolymer consisting essentially of a specific polymerizable monomer and methyl methacrylate and suitable for a full molding method without damaging expandability and moldability and emitting black smoke and soot in burning. CONSTITUTION:A resin composition obtained by polymerizing (A) 3-90wt.% polymerizable monomer expressed by the formula (R1 is H or methyl; R2 is bifunctional organic group; R3 is 6-20C alicyclic hydrocarbon; n is 0 or 1) (e.g. cyclohexyl methacrylate) with (B) 10-97wt.% methyl methacrylate and, as necessary, (C) <=10wt.% other polymerizable monomers (e.g. styrene).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a foaming resin composition used in a full mold method or the like.

(Conventional technology) Is it possible to use synthetic resin foam for casting models?

This is known in the full mold method. Regarding the use of 1M synthetic 1M fat material for casting, examples include the old lost wax method, and the newer method is the above-mentioned full mold method.

The lost wax method is a method in which a model is made with wax, the coating surface is covered with refractory material, and then the wax is eluted and removed to make a mold, but it takes time to elute the wax and dry the mold, and it is large. As a method of obtaining cast products, the method of obtaining castings is unsuitable, and its application is limited to relatively small cast products.

On the other hand, the full mold method creates a model using plastic foam made of polystyrene, polyacrylic acid, polymethacrylic acid, polyacrylamide, etc., buries it in sand, and injects molten metal in its original state. In this method, the plastic foam model is burned and destroyed by the heat of the molten metal, and the molten metal enters the cavity to obtain a casting.

Therefore, the full mold method is a casting method that significantly simplifies the process from making the model to mold work.

In the full mold method, models using conventional plastic foam produce a large amount of soot (carbon-like material) when burned.
It also generates gas and stains the casting surface.

Some drawbacks have been pointed out, such as the formation of pinholes inside the casting.

As a vanishing model that improved these defects,
There have been proposed methods in which ammonium perchlorate is contained in the dissipating model as described in Japanese Patent Publication No. 16925-197, and in which a catalyst for depolymerization is contained in a model for depolymerization as described in Japanese Patent Publication No. 16925/1983.

However, when these methods are examined in detail, they have the disadvantage that the work of making the model is surprisingly difficult and the effectiveness is relatively small.

For this reason, various proposals have been made regarding plastic foams, particularly from the viewpoint of polymers.

In particular, the following foams containing methacrylic acid ester as a main component have been proposed.

Japanese Patent Publication No. 49-23458 describes a foam whose main component is isobutyl methacrylate, which has good thermal decomposition properties, and whose copolymerization component is methyl methacrylate.

Furthermore, foams containing methyl methacrylate as a main component have also been proposed. However, when using a polymer of methyl methacrylate, it is not possible to sufficiently impregnate the blowing agent, and the resulting expandable particles have a low expansion ratio.

For this reason, in order to improve the foaming characteristics,
No. 4307 proposes a method of copolymerizing methyl methacrylate and styrene.

Furthermore, Japanese Patent Publication No. 50-40160 describes a method in which α-methylstyrene is added during the polymerization of methyl methacrylate for the purpose of improving the foaming properties and the copolymerization is carried out.

Further, JP-A-60-184447 describes the use of a foamed copolymer of methyl methacrylate and α-methylstyrene as a fugitive mold.

(Problems to be Solved by the Invention) However, the foam containing isobutyl methacrylate as a main component and methyl methacrylate as a copolymer component has a glass transition temperature that is extremely low compared to polystyrene foam.
The use of primary foaming and molding equipment for polystyrene foams has the disadvantage that the degree of shrinkage of the primary foamed particles and molded articles increases.

In addition, foams containing methyl methacrylate as a main component and styrene or α-methylstyrene as a copolymer component use aromatic hydrocarbons, so they also have the disadvantage of generating soot and staining the casting surface. was there.

The present invention solves these problems and provides a foaming resin composition that generates little black smoke and soot during combustion and can be easily polymerized without impairing foamability and moldability. It is something to do.

(Means for Solving the Problems) The present invention is directed to general The present invention relates to a foaming resin composition containing a polymerizable monomer represented by the formula hydrocarbon group Ji, where ' is 0 or 1) and a copolymer containing methyl methacrylate as an essential component.

First, the polymerizable monomer represented by general formula (1) will be explained.

R1 in general formula (1) is hydrogen or methyl.

Those with methyl groups are preferred because they exhibit better foaming properties.

R1 in general formula +1) is a divalent organic group.

, an alkylene group having 1 to 12 carbon atoms, an oxaalkylene group having 1 to 12 carbon atoms, and the like are preferable. Here, the oxaalkylene group is a divalent organic group in which an oxygen atom is bonded between two or more alkylene groups, and R40R5
, Re OR? O-几、-9-Re OR16
0-Rin! 1-〇-几12-(However, R4゜㇠s, Rs,
Ry, Rs, 几*, R16t Rtt and RtZ are alkylene groups), etc. Specifically, R2 is -CH! +, -c FujiH4*-Cs
Hs + C4H8s C5Hto #C
zH40CzH4, C5Hs OC3H@ -Cz
Examples include H4-OCxHa-〇-C-TomiH4-.

In general formula (1), n is O or l, but it is preferable that n is O from the viewpoint of better foaming properties, ease of manufacturing the monomer represented by general formula (1), economic efficiency, etc. .

R3 in the general formula (11) is an alicyclic hydrocarbon group having 6 to 20 carbon atoms. If the number of carbon atoms is less than 6, the foamability will decrease. target strength decreases.

The monomer represented by general formula (1) is produced by a known method. For example, when n is 0 in general formula (1), the structural formula is 几30H (however, 几3 is the general formula (1)
A condensation reaction between an alicyclic hydrocarbon/monool represented by 3) and acrylic acid, methacrylic acid, acrylic acid chloride, methacrylic acid chloride, etc. in the presence of an acid or alkali catalyst, It can be obtained by transesterification with methyl acrylate, methyl methacrylate, etc. In addition, in the general formula (1), the compound where n is 1 is the above-mentioned alicyclic hydrocarbon monool and HO
- & -0H (where R1 is the same as the stone in Il) Diol component 1 For example, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, etc., para-toluenesulfonic acid, silicotungstic acid, etc. condensation in the presence of an acid catalyst, HOR10-S (however.

& and R3 are the same as R1 and R3 in general formula (I)), and then can be obtained by the same condensation reaction or transesterification reaction as described above.

Alicyclic hydrocarbon monools having the structure 2-sOH include cyclohexanol, 2.2. S-trimethylcyclohexanol, cycloheptatool, cyclooctatool, cyclodecanol.

Cyclododecanol, isoborneol, borneol, π-borneol, ω-borneol.

1-adamantanol, 2-adamantanol.

3-methyl-1-adamantanol, turtle 5-dimethyl-1-adamantanol, 3-ethyladamantanol,
3-methyl-5-ethyl-1-adamantanol,
turtle s, s-triethyl-1-adamantanol, he5-
Dimethyl-8-ethyl-1-atamantanol, fenthyl alcohol, 2-methylcamphanol, l! -menthol, 8-hydroxy-tricyclo[5,21,0
] Decane, 9-hydroxy-tricyclo[5,2,1,
0”] decan.

3.7.7-t+)methyl-4-hydroxy-bicyclo(4,1,O)heptane, 3-hydroxy-46,6-
Examples include trimethyl-bicyclo(al, 1.1 heptane, etc.) Therefore, monomers represented by the general formula (11) include those having structures corresponding to these.

Among the monomers represented by the general formula (11), those that exhibit particularly good properties include cyclohexyl methacrylate, cyclododecyl methacrylate, and tricyclo(s) acrylate.
, 2. i, o'-'3dec-8yl, tricyclo[5,λ1.0'-']dec-9yl acrylate, tricyclo[5,2,1,046]dec-8yl methacrylate.

Tricyclo[5,2,1,0”)deca-9 methacrylate
Preferably used are yl, bornyl methacrylate, imbornyl methacrylate, norbornyl methacrylate, norbornane methyl methacrylate, l-menthyl methacrylate, adamantyl methacrylate, dimethyladamantyl methacrylate, and the like.

It is preferable that one or more monomers represented by the general formula (1) are contained in the copolymer in an amount of 3 to 90% by weight. If the monomer represented by the general formula (11) is too small, the expansion ratio tends to decrease, and if it is too large, the bending strength of the foam molded product tends to decrease.

The copolymer also contains methyl methacrylate as an essential component. It is preferable that methyl methacrylate is contained as a component in the copolymer in an amount of 10 to 97% by weight. If the amount of methyl methacrylate is too low, foaming properties tend to be poor.
If the amount is too large, the mechanical strength of the copolymer tends to decrease.

The copolymer may also contain other polymerizable monomers other than the monomer represented by the general formula (11) and methyl methacrylate. Examples of other polymerizable monomers include styrene,
Styrenic monomers such as vinyltoluene, isopropylstyrene, α-methylstyrene, af-methylstyrene, chlorostyrene, tertiary-butylstyrene, acrylic esters such as butyl acrylate, ethyl acrylate, methyl acrylate, and methacryl. methacrylic acid esters such as butyl acid, ethyl methacrylate, and 2-ethylhexyl methacrylate; monofunctional polymerizable monomers such as acrylonitrile, methacrylonitrile, vinyl acetate, α-methylethylene, and diethyl maleate;

Examples include polyfunctional polymerizable monomers such as divinylbenzene, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate.

When using other polymerizable monomers, the monofunctional polymerizable monomer is preferably contained in the copolymer in an amount of 10% by weight or less, and the polyfunctional polymerizable monomer is preferably contained in the copolymer in an amount of 10% by weight or less. Preferably, it is contained as a component in the polymer in an amount of less than 5% by weight. When the amount of other polymerizable monomers increases, the foaming properties tend to deteriorate.

The copolymer can be obtained by any method such as solution polymerization, emulsion polymerization, or 1M turbidity polymerization.

In the polymerization of the copolymer, examples of the polymerization initiator used include benzoyl peroxide.

Monofunctional organic peroxides such as lauroyl peroxide, tert-butyl perbenzoate, tert-butyl perbivalate, 1,1-di to 7'-thylperoxy 3,3,5-trimethylcyclohexane, di-t-
Butyl peroxyhexahydroterephthalate, di-t
-butylperoxy-trimethyladipate, di-t-
Organic peroxides such as difunctional organic peroxides such as butyl peroxyisophthalate, azo compounds such as azobisisobutyronitrile and azobisdimethylvaleronitrile, and the like are used.

The above-mentioned polymerization initiator may be added before adding the monomer into the bipolymerization container, added after adding the monomer, or added together with the monomer. The polymerization initiator is preferably used in an amount of 0.01 to 10% by weight based on the total amount of monomers.

(9) In order to adjust the molecular weight of the copolymer, n-dodecylmercaptan, n-octylmercaptan, n-butylmercaptan, tert-butylmercaptan, etc. can be used. These are preferably used in an amount of 1 molar or less based on the monomer.

The polymerization temperature is appropriately selected between 0 and 200°C.

As the suspending agent used when polymerization is carried out by suspension polymerization, those that have been widely used conventionally can be used, including polyvinyl alcohol, methylcellulose, polyacrylamide, etc. Water-soluble polymers and calcium phosphate.

Examples include sparingly soluble inorganic substances such as magnesium pyrophosphate. Water-soluble polymer is 0.03 to 1% by weight based on the total amount of monomers
It is preferable to add the slightly soluble inorganic substance in an amount of 0.05 to
0.5% by weight is preferred. Further, as a suspending agent, an anionic surfactant such as sodium dodecylbenzenesulfonate can be added, and this is preferably used in combination when a sparingly soluble inorganic substance is used as a suspending agent. The amount used is 0.001 to 0.0 based on the total amount of monomers.
It is preferable to use 2fif%. Furthermore, during suspension polymerization, an electrolyte such as sodium sulfate, common salt, or acidic sodium sulfite can be added to the aqueous medium in order to adjust the particle size of the resulting polymer. The amount of electrolyte used is preferably from 0.000 to 3% by weight based on the total amount of monomers.

When polymerization is carried out by solution polymerization, as a solvent.

Benzene, toluene, xylene, methyl ethyl ketone,
Methyl isobutyl lactone, ethyl acetate, butyl acetate, dichloroethylene, etc. can be used.

In the present invention, other polymers than the above-mentioned copolymer,
It can also be used in conjunction with the above copolymers. Other polymers other than the above-mentioned copolymers include:

Examples include one or more polymers of the other polymerizable monomers mentioned above. When these other polymers are used in combination, they are preferably used in an amount of 10% by weight or less based on the copolymer.

As the blowing agent used in the present invention, a readily volatile organic compound that is liquid or gaseous at normal temperature and normal pressure and does not dissolve the above polymer can be used. 9 for something like this
For example, propane, butane.

Examples include aliphatic hydrocarbons such as pentane, hexane, and petroleum ether, cyclic hydrocarbons such as cyclohexane, and halogenated aliphatic hydrocarbons such as methylene chloride, trichlorotrifluoroethane, and dichlorodifluoroethane. The amount of these blowing agents used is 1 to 2 parts by weight per 100 parts by weight of the 9-polymer.
It is preferable to use it in a range of 0 parts by weight.

To impregnate a polymer with a readily volatile organic compound.

When employing suspension polymerization as a method for producing polymers.

This can be carried out by adding, preferably by press-feeding, a readily volatile organic compound to the double polymerization system during the latter half of the polymerization. Here, the latter half of the polymerization refers to the time point when the 9-polymerization conversion rate is 50% by weight or more, preferably 70% by weight or more. Another method is one in which spherical or pellet-shaped particles of the polymer of the present invention are suspended in an aqueous medium and an easily volatile organic compound is added thereto. Impregnation under suspension 2
Preferably, the temperature is 0 to 130°C. As another method, the polymer of the present invention and the easily volatile organic compound may be melt-mixed. In this case, extruders are mainly used.

Also, as a blowing agent, nitrogen gas is produced by thermal decomposition.

A pyrolytic chemical blowing agent that generates a gas such as 00w gas may also be used. These include azodicarbonamide, azobisisobutyronitrile, diazoaminobenzene, N,N'-dinitrolipene memethylenetetramine, benzenesulfonylhydrazide, trihydrazinotriazine, and the like.

It is preferable that such a blowing agent is contained in an amount of 0.5 to 10 parts by weight based on the weight of the polymer.

When using a pyrolytic blowing agent, the polymer of the present invention and the blowing agent are melt-mixed at a temperature below the decomposition temperature of the blowing agent. Also at this time, an extruder is mainly used.

A plasticizer may be present during impregnation of the polymer with the blowing agent. As a plasticizer, an organic solvent that can dissolve or swell the 9-polymer can be used, and its boiling point is 2.
At a temperature that is approximately 10°C lower than the softening point of the polymer and 150°C
℃ or less is preferable. Examples of the plasticizer include aromatic hydrocarbons such as ethylbenzene, toluene, styrene, benzene, and xylene, and halogenated hydrocarbons such as 1,2-dichloropropane, trichloroethylene, and perchloroethylene. The plasticizer is preferably used in an amount of 0 to 5 weight - 1 i% based on the polymer.

Furthermore, the foaming resin composition according to the present invention includes the following.

Known additives such as pigments, M fuel agents, antioxidants, and antistatic agents may also be included.

The foaming resin composition according to the present invention is heated.

This is done using methods such as depressurization. As the method, the foaming and molding methods of styrenic resin, which are widely used industrially, can be applied as they are. For example, if the resin is in the form of particles, it can be pre-foamed with steam and then further steam-foamed in a molding machine to obtain a molded product. Moreover, a foam can also be obtained using an extrusion foaming machine.

The foaming ratio of the foaming resin composition according to the present invention is as follows.

The magnification can be arbitrarily selected from low magnification to high magnification.

The foam obtained from the foamable resin composition according to the present invention can be used in addition to the full mold method.

Insulating materials for air conditioners, hot water tanks, insulating materials for metal tiles, insulating materials for school lunch containers, insulating materials for vehicles and ships, insulating materials for hot water pipes, wind barrels for near conditioners, sizing boards, and structural materials for automobiles.

Examples include metal co-forming panels.

(Examples) Hereinafter, the present invention will be explained in more detail using examples. In addition, hereinafter, "part" and "chi" are based on weight.

Examples 1-11 and Comparative Examples 1 to 3 5 g of lauroyl peroxide and 1.1-zit were added as a polymerization initiator to a mixed solution of the monomers shown in Table 1.
0.59 -butylperoxy[lambda]-5-trimethylcyclohexane and n-octylmercaptan in the amount shown in Table 1 as a molecular thtH14 stabilizer were dissolved. Add this solution to 3I! 6 g of tricalcium phosphate 29e sodium dodecylbenzenesulfonate 0.5% solution and 0.759 sodium sulfate were dispersed or dissolved in 1500 g of water in an autoclave, and added to the aqueous solution under rotational stirring at 270 rpm. Furthermore, the atmosphere inside the autoclave was reduced to N.
! Replaced with. Next, the temperature was raised to 70°C, and after stirring at that temperature for 5 hours, pentane and toluene in the amounts shown in Table 1 were added. Then, the temperature was raised to 100°C, and the mixture was stirred at the same temperature for 4 hours. Thereafter, it was cooled, and the polymer particles for foaming were taken out, washed with hydrochloric acid, washed with water, dehydrated, and dried.

The average particle diameter and total volatile component content of the nine foamable polymer particles obtained were measured and shown in Table 1. 9 In the present invention, the average particle diameter is determined by sifting the particles obtained by polymerization into each particle size, and sequentially dividing each sieved particle into 1 particle from the smallest particle size.
Create a curve plotting cumulative weight against particle size,
This shows the particle size at which the cumulative weight is equivalent to 50%.

Also.

To determine the total volatile content, take 2g of the sample in an aluminum dish and heat it at 200°C.
Heat for 10 minutes and measure the weight, [(sample weight before heating) - (weight after heating)] / (sample weight)
Expressed in 100.

The expandable polymer particles were immersed in boiling water at 100° C. for the heating time shown in Figure 1 to produce pre-expanded particles. The specific volume of the pre-expanded particles was measured and shown in Table 1. In addition, the specific volume is 1000 ml! The pre-expanded particles were packed into a measuring cylinder, and the weight was measured, and the volume/weight ratio was determined.

Furthermore, the pre-expanded particles were aged in air at 25°C for 24 hours, put into a mold, and heated with steam at 1.0 kg/c♂-G (120°C) in a table autoclave as shown in Table 1.
A foamed molded product was obtained by heating for the time indicated in . The specific volume of this foam molded product was measured and shown in Table 1.

The obtained foamed molded product was visually evaluated for the presence or absence of shrinkage (1) for surface smoothness, and then ignited (9) to evaluate the generation of black smoke and soot. These evaluation results are shown in Table 1.

□□□□□ Margin below (Effects of the invention) The foaming resin composition of the present invention has no shrinkage of the foam obtained thereby, and its surface has good smoothness.
Moreover, no black smoke or soot is generated during combustion.

Agent: Patent attorney Kunihiko Wakabayashi 1.1.

Claims (1)

[Claims] 1. General formula (I) ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (However, R_1 is hydrogen or a methyl group, R_2 is a divalent organic group, and R_3 is Foaming product containing a copolymer containing a polymerizable monomer (which is an alicyclic hydrocarbon group having 6 to 20 carbon atoms, where n is 0 or 1) and methyl methacrylate as essential components Resin composition.