JPS6023017A - Preparation of foam molded object with strong skin - Google Patents

Abstract

PURPOSE:To obtain the title tough and heat-resistant foam by a method wherein humidity is let to act on the surface of B-stage polyisocyanurate resin bulky object to provide a high-molecular skin, then, said bulky object is heated and expanded in molds. CONSTITUTION:First, organic polyisocyanate (preferably, trilene-2,4-diisocyanate etc.) and/or isocyanate groups-containing prepolymer (preferably, a reactant of low molecule diol etc. and organic isocyanate) is reacted under the presence of trimer catalyst (preferably, triethylene etc.) to obtain B-stage polyisocyanulate resin bulky object. Then, by keeping said bulky object in a wet atmosphere or the like, moisture acts on the surface of said bulky object to provide a high molecule skin and then the mold is charged with said bulky object and the bulky object is heated, expanded to obtain the desired molded piece.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a foam molded article having a strong skin, and more particularly to a method for producing a polyisocyanurate foam.

In recent years, efforts have been made to reduce the weight of transportation machines from the viewpoint of energy conservation, and the use of polymer foams for structural members of automobiles and aircraft, for example, is being considered.

In addition, the use of polymer foams, which have excellent heat resistance and heat insulation properties, is being actively promoted for solar heat utilization equipment and partition walls around engines.

Conventionally, the use of polyurethane rigid foams has been considered for these applications, but they have low heat distortion temperatures and limited heat resistance, and have not been able to fully satisfy the required properties.

Polyurethane rigid foam contains a large amount of urethane bonds with strong intermolecular attraction, so it can form a strong foam, but since the heat resistance of urethane bonds is inherently poor,
It is impossible to withstand a long period of time under an ambient atmosphere of ℃ or higher.

When organic polyisocyanate is polymerized in the presence of a trimerization catalyst, a polyisocyanurate resin is formed.The isocyanurate ring structure formed in this case inherently has excellent heat resistance, so this resin is incorporated into the resin. Many studies have been conducted to obtain heat-resistant foams by introducing structures. However, the polyisocyanurate-1 foam obtained in this way is very brittle due to its -11 direct chemical formation and three-dimensional network polymer structure, and when the surface of the foam is rubbed, it becomes powdery. Due to the physical properties of ``Parakugangashi'', which tend to turn into
The field of application of the final product was very limited. In order to improve these "rakugan"-like physical properties, attempts have been made to introduce flexible structures, including urethane modification with polyols, oxa/lydone modification with epoxy resins, and amide modification with carboxylic acids. Since all of these modifications reduce the heat resistance of the polyisocyanurate resin, most of the modifications that are satisfactory in terms of flexibility improve the heat resistance of the polyurethane rigid forno to a degree of 11]. In general, the brittleness of polyisocyanurate foams, which cannot be said to fully satisfy recent demands for high heat resistance, is due to the following points.

1. Because the cross-linked chains are rigid and the structure has a high three-dimensional network density. 2. The cross-linking reaction is not completed sufficiently and the reaction freezes in the branched low molecular weight material. Although it is a condition,
Rather than being the essential cause of the 'xi'-like brittleness of polyisocyanurate foams, in many cases this brittleness is brought about by item 2. Therefore, as the isocyanurate ring structure increases, brittleness tends to occur, and it has been extremely difficult to obtain a polyisocyanate foam that has both mechanical strength and heat resistance. ``Rakugan''''
The polyisocyanurate foam, which has similar brittleness, is found to have a sharp dog at a wave number of 225.0 CI++' based on the insium group when its infrared absorption spectrum is examined as a tablet after powdering ~ part of it with potassium bromide crystals. A slight absorption was observed, indicating that the crosslinking reaction was not fully completed.

This absorption gradually decreases with heating time when heat-curing at a temperature of 150 to 250°C, but since cracks occur in the foam, hardly any improvement in mechanical strength can be expected. This is due to the formation of crosslinks due to incyanurate ring formation of the remaining isonoatom groups due to prothermal curing, and carbodiimide formation, which deforms the cell walls of the polyisocyanurate resin foam due to the pressure of released carbon dioxide gas. This is thought to be for the purpose of destroying or destroying it.

Therefore, with such a method, even if the degree of completion of the crosslinking reaction is increased, a foam with excellent mechanical strength cannot be obtained.

In order to overcome the conventional problems mentioned above, the inventors conducted extensive research and finally discovered a method for producing a strong foam with excellent heat resistance.

That is, the present invention provides the following steps: applying moisture to the surface of a B-staged polyisone annulate resin mass obtained by polymerizing an organic polyisocyanate and/or incyanate group-containing prepolymer in the presence of a trimerization catalyst; This is a method for producing a foamed molded article, which is characterized in that after forming a polymeric skin, the mass is filled into a mold and heated and foamed.

Moreover, in the above, a polyhydroxy compound and/or a polyamine can be used instead of moisture.

In the present invention, the organic polyinsyanates include aliphatic, cycloaliphatic, aromatic substituted aliphatic, aromatic, or heterocyclic polyiso/anates, such as tetramethylene-substituted aliphatic, aromatic, or heterocyclic polyiso/anates.
I+4-'2 incyanate, hexamethylene-1,6
-diisocyanate, octamethylene-1,8-diisonane-1, dodecamethylene-1,12-diyn7anate, 2,2.4- or 2°4.4-trimethylhexamethylene-1,6-diisocyanate, 1 -incyanate-3,3,5-)methyl-5-inyanate methylcyclohexane, cis- or tra
ns-cyclohexane-1,4-diisocyanate, dicyclohekiflumethane-4,4'-diiso7anate,
1-Methylcyclohexane-2,4- or -2,6-
Diisocyanate methyl-1,4- or 1,3-cyclohexane, 3.1
0-diiso/achitotricyclo[5,2,1,,02
°6] Decane, 2,2-bis(4-incyanatecyclohexyl)propa/, 618-diincyanatebicycloC3,3,0)octyne, tolylene-2,4- or -2,6-diyne/anate, diphenylmethane −
2,4'- or -4+4'-cyisocyanate, naphthylene-1,5-diisocyanate, bitolylene diisocyanate, anine diiso7a-1-, diphenyl ether-4,4'-cyinonanate, nl-also I't p -Phenyle/diisocyanate, triphenylmethane-4,4', ,r'-)lyiso7ane-1
, tris(4-isocyano-un-tofgonyl)thiophosphate, undecane-1,6゜10-triiso/anate, xy/rylene-1,3- or 1,4-diynoaun-1., lysine diiso/anate methyl ester , N
, N'-bis(ω-incyanatepropyl)oxadiazinetrione, polyphenylpolymethylenopolyiso/anate of the type obtained by formalizing/condensing aniline and then phosgenating, 4 German special 1ff (10920
Diphenylmethane diisocyanates that are liquid at room temperature and have a carbodiimide group and a matahuretonimine group as described in No. 07 specification, or urethane bonds,
Examples include modified polyinyanates containing allophanate bonds, urea bonds, biuret bonds, uretidinedione ring structures, etc., and the above polyisocyanates include 1
It can be used as a species or a mixture of two or more.

Among these, trilene-2,4-diyne/7-methyl and trilene-2,4-diyne/7-methyl, which can form stable and staged polyiso/anurate resins, have good heat resistance, and are commercially available. 6-diyne/imortho, or any mixture of these isomers, polyphenylpolymethylenopolyisocyanates obtained by condensation of aniline with formalin and subsequent phosgenation, diphenylmethane-4,4'-diisocyanate-1, and diphenylmeth-7-2,4'-cyinoneanate or any mixture of these isomers,
Particularly suitable are liquefied phenylmethane diisocyanes-1.

The incyanate group-containing prepolymer used in the present invention is obtained by reacting an excess organic polyisocyanate with a compound that forms a cyclic bond or a chain bond with an incyanate group, and is For example, polyoxazolidone from an epoxy compound, the prepolymer from polyimide from an acid anhydride, etc. can be mentioned. Also,
Examples of compounds that form chain bonds include reaction products from active hydrogen compounds and excess organic polyinanoate, and active hydrogen compounds used for this include, for example, hydroxyl compounds, thiol compounds,
These include amino compounds and carboxyl compounds. Among the above, particularly preferred incyanate group-containing prepolymers are:
Polyhydroxyl compound and excess organic polyyne/
derived from anates, such as ethylene glycol, propanediol, phthanediol, bentanediol, hexanediol, diethylene glycol, lebropylene glycol, 2,2-bis(4-hydroxyphenyl)propane, and 1,4-cyclohexanedimethanol. Hydroxyl group-terminated polyols obtained by addition polymerization of alkylene ogyne (?) using an active hydrogen compound as an initiator; Ethers, polyols with a molecular weight of 500 to 7,000, such as hydroxyl-terminated polynisderes used in the polyurethane industry, and hydroxyl-terminated hydrocarbon chain polymers, and mixtures of one or more of these. It is obtained by reacting excess organic polyiso/anate.Also,
Such an incyanate group-containing prepolymer can also be used as a mixture with the organic polyisocyanate in any ratio.

As the trimerization catalyst used in the present invention, known ones can be used. For example, alkali metal salts of carboxylic acids having 2 to 12 carbon atoms (potassium acetate, potassium propionate, potassium adipate, potassium benzoate, etc.), alkali metal salts having 13 or more carbon atoms (for example, potassium oleate), Weakly basic substances such as alkali metal salts of weak acids other than carboxylic acids such as sodium oxide, strong basic substances such as sodium methoxide, benzyltrimethylammonium hydroxide, and alkali metal hydroxides,
Chelate compounds typified by chelate compounds of salicylaldehyde and potassium, metal salts other than alkali metals of carbo/acids such as cal/umium naphthenate, lead naphthenate, lead caprylate, triethylamine, tripropylamine/
, tributylamino, N-methylmorpholine, N, N'
-dimedyl biverane, 2.4.6- tris(dimethylaminomethyl)phenol, N, N', N''-)
Lis(dialkylaminoalkyl)hexahydro-5-
These include tertiary amines such as triazine, and combinations of tertiary amines and promoters, such as combinations of tertiary amines and phenols or epoxy compounds.

These trimerization catalysts can be used alone or as a mixture of two or more. Among these, particularly preferred catalysts are:
Tertiary amines such as triethylamine, 2,4.6-)lis(dimethylaminomethyl)phenol, N,N',N"-tris(dimethylaminopropyl)hexahydro-5-)riazine, or Combination of grade amine and butylene oxide, Al-Iha, carbon number 2~
These are alkali metal salts of 12 carboxylic acids, and these are excellent in catalytic activity and compatibility with compounding systems.

As a promoter of the trimerization catalyst in the present invention, an epoxy compound can be used as necessary.

Suitable epoxy compounds to be used if necessary include, for example, allyl glycine ether, butyl glycidyl ether, phenyl glycidyl ether, butylene oxide, propylene oxide →i-ide, glinodol, octylene oxide, styrene/oxide, parza Examples include grindyl ester of tick acid and digrindyl ether of bisphenol.

B-staged polyisocyanuride in the present invention)
1jl A fat mass is a prevalent polymer with a branched structure resulting from the trimerization reaction of polyisocyanate, and is cooled to below its glass transition point before it becomes reticulated or gelled, and the trimerization reaction is frozen. The chemical structure can be expressed as follows.

": In the formula, R is the residue of the polyincyanate excluding the incyaneto group, f is the functional number of the polyisonoanate,
1] indicates the degree of polymerization of polyinocyanurate. f is usually 2 to 3, particularly preferably 2. Although n is a number with a distribution, it is particularly preferable that the main component is 1 to 2. These influence the heating foaming behavior, and in the case of large f and n, the softening point and viscosity at the time of softening are high, resulting in a high-density foam, whereas in the opposite case, a low-density foam is obtained. .

The above lumps are produced by heating polyinsyanate in which a trimerization catalyst has been dissolved, keeping it in a molten state, pouring it into a cooled dish or mold just before reaching a predetermined degree of polymerization, vitrifying it, and then pulverizing or molding it. It can be used as a granular vitrified form by dropping it into a cooled medium.

In the improved method for producing a foamed molded article according to the present invention,
It is also possible to add a carboleimidation catalyst together with a trimerization catalyst. As the carbodiimidation catalyst, known catalysts can be used, such as trimethyl phosphate, tributyl phosphite, tributyl phosphine oxide, phospholine, phospholidine, phospholine oxide, phosporidine oxide, phospholine sulfide, and phospholidine sulfide. phosphorus compounds such as sodium metkind, alkali metal compounds such as potassium carbonate, tertiary amines such as triethylamine, tributylamine, triethylenediamine, such as lead octylate, zinc octylate, cobalt naphthenate, dibutyltin dilaurate, Examples include heavy metal compounds such as tetrabutoxytitanium and iron acetylacetonate.

In the present invention, B-staged polyisocyanurate-1.
Moisture can be brought into contact with the surface of the resin mass by leaving it in humid air or steam, or by immersing it in water. By applying moisture under heating or in the presence of a tertiary amine catalyst, etc., a polyurea skin is rapidly formed on the surface of the lump. The thickness of the polymer skin formed in this way changes depending on the conditions under which moisture acts, and increases with high humidity and long-term contact.

- When a polybitroxy compound and/or an amino compound is used instead of moisture, polyurethane-based and polyurea-based skins are formed, respectively. As the polyhydroquine compound, those mentioned above can be used.

Examples of amino compounds include primary monoamines such as ethylamine and aniline, primary polyamines such as ethylenediamine, dipenylmethane-4,4'-reami/, and 1,6,11-triaminoundeca/; These include secondary polyamines such as piperazine and triarene.

Moisture, polyhydroxyl compounds and amino compounds are
In the present invention, the B-staged polyisone annulate resin mass is filled into the mold after forming a polymeric skin, and the resin mass has a glass transition point of 2 or more. The mixture is heated to a temperature at which a carbodiimidization reaction occurs, and foam molding is performed. The foamed molded product is subjected to post-keying before or after demolding, if necessary.

In the present invention, the B-staged polyisone annulate resin mass may contain fillers, reinforcing materials, mold release agents, pigments, flexibility agents, foaming agents, deterioration inhibitors, flame retardants, etc., as necessary. A curing agent or other additives can be added.

Next, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to these examples.

Example 1 100 parts by weight of carbodiimide-modified diphenylmethane diincyanate (NGO content 28.7%), 8 parts by weight of triethyleneglyfur, 1.0 parts by weight of tri-n-butylamine.
5 ffift parts and 3 parts by weight of phenyl glycidyl ether were mixed to cause a trimerization reaction, and the exothermic temperature reached 100%.
When the temperature reached ℃, it was injected into a Teflon coated tube and rapidly cooled to obtain a 5-thick plate-like mass of B-staged polyinane annulate resin. The melting point of this product was 120°C. This lump was divided into 5 ran x 100 ran.
After cutting into X ] 00 tan, and leaving it for 15 hours in a gust of air at 25° C. and 55% relative humidity, 10 groups
The mixture was placed in a closed mold having a cavity of 0nnl x 100mm and heated in a constant temperature bath at 200°C for 4 hours. Thereafter, this mold was taken out from the thermostatic oven, and after cooling to room temperature, the contents were taken out, and a foamed molded product with a size of 9.3 tone x 98 order x 98 wire and a density of 0.61f7W was obtained. This molded product had a tough non-foamed skin of about 0.2 fi and did not exhibit any brittleness like "Pakrakugan".
When heated for 30 minutes in a constant temperature bath at 00°C, no softening or deformation was observed.

Example 2 Polyoxypropylene glyfur (molecular weight 500
) was added, stirred and mixed at 70°C for 3 hours, and N
An incyanate-containing prepolymer with a CO content of 23.2% was obtained.

100 parts by weight of the obtained prepolymer, Polycat 41
(Combination system of amine catalyst and alkali metal carboxylate, manufactured by Sun Abbott) Mix 0.35 parts by weight to cause a trimerization reaction, and when the exothermic temperature reaches 80℃, pour into a Teflon-coated vat. This was then quenched to obtain a B-staged polyyne annulate resin mass having a melting point of 110°C.

The agglomerates were coarsely ground with a hammer cranone jar to give particles of about 2 angles, and left at 25° C. and 55% relative humidity for 3 hours. This granule is 10 tan x 100 mm x 1
687 is filled into a closed mold with a cavity of 00 m,
It was heated for 4 hours in a constant temperature bath at 200°C.

Thereafter, the mold was taken out, cooled to room temperature, and the contents were taken out. A foamed molded product with dimensions of 9.5w x 99w x 99+u+ and a density of 0.69 was obtained.

This molded product is composed of granular foam with a strong skin.
Because the skin of each granular foam was fused, it did not show any 'rakugan'-like brittleness.When this foam molded product was heated in a constant temperature bath at 200℃ for 30 minutes, it did not soften or No deformation was observed.0 Example 3 ft part by weight of the prepolymer xoo obtained in Example 2, 50 parts by weight of crushed glass fiber (100 mesh), and 420.40 parts by weight of volcanic acid were mixed and trimerized. After the reaction occurred and the exothermic temperature reached 80°C, it was poured into a Teflon-coated vat and quenched to obtain a mass of B-staged polyisocyanurate resin formulation with a melting point of 120°C. Coarsely grind it with Nmarkuranoya, 2
It was made into powder and granular material with a size of about 0 mesh. Add 100 parts by weight of this powder to 3-methyl-1-phenyl-3-phosphorine-1-
After adding 0.01 part by weight of oxide, the mixture was mixed for 1 hour using a tumbler mixer. This mixed powder and granular material 1002 has a diameter of 8
Place it in a cylindrical mold with a diameter of 80mm and a height of 80W, and use a bran layer of the same shape as the mold, and mold it at room temperature with a diameter of 80mm and a height of 25mm.
A preformed compression molded body of wM was obtained. After leaving this compression molded body at 25°C and 65% relative humidity for 24 hours,
It was placed in a mold with a cylindrical cavity with a diameter of 40mm and a height of 30mm, and heated at 200°C for 3 hours. After cooling the mold, the contents were taken out and the diameter was 79.5+I++
A cylindrical foamed product with a density of 0.68 and a height of 29.5+mn was obtained. The skin of this molded product was strong and no ``rakugan''-like brittleness was observed.
When heated for 30 minutes in a constant temperature bath, no softening or deformation was observed.

Comparative Example 1 In Example 2, when the trimerization reaction was caused and left to stand, the exothermic temperature reached 160°C. In this way,
The produced Borisone annulate resin showed a slight softening tendency at 150°C, but did not have a clear melting point.

Hereinafter, this product will be referred to as Example 2. Molding in the same manner as 1. However, an integral foam molded product could not be obtained.

Comparative Example 2 Example 1. Immediately put a 51 ml thick plate-like block of B-staged polyin cyanurate resin into a closed mold for 20 minutes.
When heated at 0° C. for 4 hours, the resulting foamed molded product had a brittle skin similar to that of a parrot.

Claims (1)

[Claims] 1. Organic polyisocyanate and/or incyanate group-containing prepolymer in the presence of a trimerization catalyst.
(The surface of the resulting B-staged polyisocyanurate resin mass is applied with moisture to form a polymer skin, and then the mass is filled into a mold and heated and foamed.) A method for producing a foamed molded product having a strong skin. 2. The method according to claim 1, wherein a polyhydroxy compound and/or an amino compound is used instead of moisture.