JP2618804B2 - Method for producing foamed polyurethane moldings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a lightweight and uniform foamed polyurethane molded article having no density distribution. More specifically, the present invention relates to a method for producing a foamed polyurethane molded product suitable for a model material having a small amount of dust generated during cutting and having good heat resistance.

[0002]

2. Description of the Related Art Conventionally, there is a technique for producing a rigid polyurethane foam having a low density distribution by combining a high molecular weight polyol and a low molecular weight polyol and reducing the weight by a mechanical floss method (for example, JP-A-4- 356517).

[0003]

However, when the rigid polyurethane foam obtained here is cut as a model material, generation of dust is unavoidable. 2. Description of the Related Art In recent years, work environment improvement has been emphasized, and a demand for reduction of generated dust has increased. As a means for suppressing the generation of dust during cutting, a method of lowering the crosslink density of the resin can be considered, but in that case, it is not suitable as a model material because it has poor heat resistance and softens when the temperature rises.

[0004]

Means for Solving the Problems The inventors of the present invention have made extensive studies on a foamed polyurethane molded product which produces a small amount of dust during cutting without lowering the heat resistance, and as a result, uses a specific polyol. The inventors have found that the above problems can be solved by the present invention, and have reached the present invention.

That is, the present invention comprises an aromatic ring-containing polyol (a) having a hydroxyl value of 200 to 400 represented by the following general formula and an aliphatic polyol (b) having a hydroxyl value of 250 to 500. Polyol component (A) wherein the weight ratio of (b) is 10/90 to 40/60
And an aromatic polyisocyanate component (B) and 1 to 8 parts by weight of the dehydrating agent (C) per 100 parts by weight of the polyol component (A) are foamed by a mechanical floss method without using a foaming agent. And a method for producing a foamed polyurethane molded article.

[0006]

(Wherein X is a group of H, CH3, Cl or Br; -Y- is -CH2-, -C (CH3) 2-, -SO2
-, -O-, a single bond group; A is a propylene group or an ethylene group; and m + n is a number from 0 to 13. )

The aromatic ring-containing polyol (a) in the present invention includes bisphenols, polyols obtained by adding alkylene oxide thereto, and mixtures of two or more thereof.

Specific examples of the above bisphenols include:
For example, bisphenol A [2,2'-bis (4-hydroxyphenyl) propane], bisphenol F [2
2'-bis (4-hydroxyphenyl) methane], bisphenol S [2,2'-bis (4-hydroxyphenyl) sulfone], 2,2'-bis (4-hydroxyphenyl) ether, 4,4'- Dihydroxybiphenyl,
2,2'-bis (4-hydroxyphenyl) hexafluoropropane is exemplified. Bisphenol A and bisphenol F are preferred.

The above bisphenols can be used as they are as the aromatic ring-containing polyol (a), but the alkylene oxide adducts thereof are more preferable. Examples of the alkylene oxide include propylene oxide (hereinafter abbreviated as PO), ethylene oxide (hereinafter EO).
And a combination of these two (block and / or random addition). Preferred is
It is a combination of PO and PO / EO.

The hydroxyl value of the aromatic ring-containing polyol (a) used in the present invention is usually from 200 to 400, preferably from 250 to 350. When the hydroxyl value is less than 200, the heat resistance of the obtained foamed polyurethane molded product is not sufficient, and when it is more than 400, it tends to be hard and brittle.

As the aliphatic polyol (b) in the present invention, an alkylene oxide (for example, PO, EO and a combination of these two types) adduct of a polyhydric alcohol may be mentioned. Examples of the polyhydric alcohol include alcohols having 2 to 8 hydroxyl groups in one molecule, such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, glycerin, trimethylolpropane, pentaerythritol, and methyl. Glycoside, diglycerin, sorbitol, glucose, sucrose. Preferably, it has 2 to 4 hydroxyl groups, such as propylene glycol, glycerin, pentaerythritol and methyl glycoside.

The hydroxyl value of the aliphatic polyol (b) is usually 200 to 500, preferably 250 to
It is 450. When the hydroxyl value is less than 200, the heat resistance of the obtained foamed polyurethane molded product is deteriorated, and
If it exceeds 0, the generated dust increases.

The weight ratio of the aromatic ring-containing polyol (a) to the aliphatic polyol (b) is from 10/90 to 40/60, preferably from 10/90 to 30/70.

When the proportion of the aromatic ring-containing polyol (a) is large, the resulting foamed polyurethane molded article has high toughness, and as a model material, the cutting workability is reduced. On the other hand, when the ratio of the aliphatic polyol (b) is large, the obtained foamed polyurethane molded product becomes hard and brittle, and when used as a model material, much dust is generated during cutting.

As the polyol component (A) of the present invention, polyols other than the above (a) and (b), such as polybutadiene polyol, acrylic polyol, polymer polyol modified with an ethylenically unsaturated monomer, and bisphenols Other aromatic ring-containing polyols (for example, hydroquinones, condensates of phenolformaldehyde, aromatic ring-containing polyester polyols, and polyols obtained by adding alkylene oxide thereto; alkylene oxide adducts of aromatic amines), etc. Can be used together.

As the aromatic polyisocyanate (B) used in the present invention, those conventionally used for polyurethane can be used. Examples of such aromatic polyisocyanates include ordinary aromatic polyisocyanates and modified products thereof (for example, carbodiimide groups,
Allophanate groups, urea groups, burette groups, isocyanurate groups, oxazolidone group-containing modified products, etc.), isocyanate group-terminated prepolymers and mixtures thereof.

Specific examples of such aromatic polyisocyanates include 1,3- and 1,4-phenylene diisocyanate, 2,4- and / or 2,6-tolylene diisocyanate (TDI), crude TDI, Diphenylmethane-2,4'- and / or -4,4'-diisocyanate (MDI), polymethylene polyphenylisocyanate (crude MDI), naphthylene-1,5-diisocyanate, triphenylmethane-4,4 '. ，
4 ''-triisocyanate, carbodiimide modified MD
I, polyhydric alcohols such as sucrose, and isocyanate group-terminated prepolymers of TDI. Of these, preferred are TDI, crude TDI, MDI, and crude MDI.

The ratio of the polyol component (A) to the aromatic polyisocyanate (B) can be variously changed,
The equivalent ratio of the hydroxyl group of (A) to the isocyanate group of (B) is usually 1.0: 0.5 to 1.0: 1.5, preferably 1.0: 0.9 to 1.0: 1. It is 2. Further, the equivalent ratio of the hydroxyl group to the isocyanate group is set to 1.0: 1.
When the ratio is 5 to 1.0: 50, a polyisocyanurate foam can be produced.

As the dehydrating agent (C) of the present invention, a compound having a commonly used dehydrating effect can be used, but a neutral or alkaline dehydrating agent having a particle size of usually 0.1 to 50 μm is preferable. Examples thereof include hydroxides, oxides or salts of metals belonging to Groups II, III and IV of the Periodic Table of the Elements. Specific examples include barium hydroxide, calcium oxide, calcium sulfate (hemihydrate gypsum), calcium chloride, and zeolite (sodium aluminosilicate). Preferably, calcium sulfate and zeolite are used.

The amount of the dehydrating agent (C) is usually 1 to 8 parts by weight per 100 parts by weight of the polyol component (A),
It is preferably 2 to 6 parts by weight. If the amount of the dehydrating agent (C) is less than 1 part by weight, the dehydrating effect is insufficient, so that water mixed by moisture absorption reacts with isocyanate to cause a foaming phenomenon, resulting in an uneven density distribution of the obtained polyurethane foam molded product. Prone. Further, even if it exceeds 8 parts by weight, no further dehydration effect is obtained, and the machinability deteriorates.

In the method for producing a foamed polyurethane molded article in the present invention, a mechanical floss method, that is, a mixer having a high shearing force such as an Oaks mixer is used, and the polyol component (A) and the organic polyisocyanate component (B) are used. It is carried out by mixing an inert gas into the liquid phase composed of the above. The Oaks mixer is a mixer suitable for continuously mixing gas. Other
The inert gas may be mixed in a batch method, for example, a Hobart mixer is used.

The inert gas mixed in by the mechanical froth method of the present invention does not react with the polyol component (A) or the aromatic polyisocyanate component (B) and is at −30 at atmospheric pressure.
Gases that are not liquid at ° C are included. Preferably air,
Nitrogen and carbon dioxide. The volume content of the inert gas in the composition is usually 10 to 80%, preferably 20 to 80%.
70%. Molded product usually has a density of 0.2-0.9g
/ Cm3, preferably from 0.3 to 0.8 g / cm3.
It is.

In the method for producing a foamed polyurethane molded article of the present invention, by further using the hollow body (D),
Not only the weight can be reduced by the specific gravity of the hollow body (D) itself, but also the nucleating agent when the inert gas is mixed, the effect of weight reduction is further enhanced. Examples of the hollow body (D) of the present invention include closed-cell hollow bodies of inorganic compounds or organic compounds. The size and bulk specific gravity are not particularly limited, but usually the size is 10 to 500 μ, and the bulk specific gravity is 0.01 to 0.5.
0 g / cm3 can be used. For example, examples of the inorganic hollow body include an alumina balloon, a glass micro balloon, a shirasu balloon, a carbon balloon, and a hollow body made of silica or fly ash. Examples of the hollow organic material include phenolic microballoons (phenolic resin hollow bodies manufactured by Union Carbide), Saran microspheres (polyvinylidene chloride hollow bodies manufactured by Dow Corning), Matsumoto Microspheres (polyacrylonitrile resin hollow bodies manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.). ) And hollow bodies made of synthetic polymers such as urea resin, polyvinyl acetate, polymethyl methacrylate, polyurethane, and epoxy. Preferably, glass mikle balloon, shirasu balloon, phenolic micro balloon,
This is the Matsumoto Microsphere.

The amount of the hollow body (D) is usually 2 to 20 parts by weight, preferably 5 per 100 parts by weight of the polyol.
１５15 parts by weight. When the amount of the hollow body (D) is less than 2 parts by weight, the cured polyurethane foam molded article is liable to have a density distribution. If it exceeds 20 parts by weight, the viscosity of the composition remarkably increases, and it becomes difficult to mix and stir with an Oaks mixer, and as a result, a homogeneous molded product cannot be obtained.

In the present invention, if necessary, the polyol component (A) may contain another active hydrogen-containing compound, and may be reacted with a part or the whole amount of the aromatic polyisocyanate (B). For example, a small amount of polyamine (tolylenediamine, ethylenediamine, etc.) may be used together in order to increase the reactivity.

In the present invention, a catalyst usually used for polyurethane reaction, for example, an amine catalyst [triethylenediamine, N-ethylmorpholine, diethylethanolamine, 1,8-diazabicyclo (5.4.0) undecene-7, etc.] And a metal catalyst (such as stannous octylate, dibutyltin dilaurate, and lead octylate). The amount of catalyst is based on the weight of the reaction mixture.
Usually, 0.001 to 5% by weight is used.

If necessary, a colorant (dye, pigment),
Additives such as plasticizers, fillers, flame retardants, antioxidants, antioxidants and the like can also be used.

As a method for producing the molded article of the present invention,
Typically, the following procedure is representative. (1) A dehydrating agent (C) and, if necessary, a surfactant are uniformly mixed in advance with a polyol component (A) composed of an aromatic ring-containing polyol (a) and an aliphatic polyol (b). (2) The mixture, the aromatic polyisocyanate (B) and the inert gas are uniformly mixed using an Oaks mixer or Hobart mixer, and then the mixture is poured into a mold. (3) After being cured in the mold, the mold is removed to obtain a polyurethane foam molded product. In addition to this, when the curing reaction is relatively slow, after preliminarily mixing the polyol component (A) containing the dehydrating agent (C) and the aromatic polyisocyanate (B), an inert gas is further uniformly mixed, It can also be injected into the mold.

In the case of stirring with an Oaks mixer,
5 to 10 L / min of a mixture of (A) and (C) (temperature 20 to 4
0 ° C) and (B) 5 to 10 L / min (temperature 20 to 40 ° C), 2 to 10 L / min of inert gas (pressure 4 to 10 kg / min)
cm2 · G). In addition, in the case of stirring with a Hobart mixer, 30 to 180 rpm
It is generally desirable to stir at a rotation speed of 2 to 15 minutes. According to this method, the density can be reduced and the density distribution can be reduced. When the stirring time is 1 minute or less, a desired low density cannot be obtained, and the density distribution does not become smaller than that.

The foamed polyurethane molded article of the present invention is suitable as a model material, and is used for a master model, a copy model, a design model, an NC tape confirmation model, a styling model, an inspection jig, and the like.

[0032]

The present invention will be further described below with reference to examples, but the present invention is not limited thereto. Parts in the examples are parts by weight, and the molecular weight is the number average molecular weight in terms of hydroxyl number. Example 1 Aromatic ring-containing polyol (I) 30 having a molecular weight of 374 obtained by addition-polymerizing 174 parts of PO to 200 parts of bisphenol F 30
Part, 136 parts of pentaerythritol and 419 parts of PO by addition polymerization, aliphatic polyol (II) 7 having a molecular weight of 555
0 parts, calcium sulfate (hemihydrate gypsum) 6 parts, silicone S
H-193 (foam stabilizer from Toray Silicone Co., Ltd.) was added to a premix consisting of 4 parts, and Millionate MR-200 (crude MDI manufactured by Nippon Polyurethane Industry, NCO content 31%) 94
After adding the parts, with a Hobart mixer, 120 rpm
The mixture was stirred at a speed of m for 10 minutes. Next, the composition for forming a foamed polyurethane obtained in this manner was used at a mold temperature of 35 ° C.
The mixture was poured into an iron mold (length 20 × width 30 × height 5 cm) adjusted to ˜45 ° C., the lid was closed, and the mixture was cured in the mold. After leaving for 1 hour in a constant temperature bath at 70 ° C., the mold was removed to obtain a molded polyurethane foam. The density distribution, heat distortion temperature and dust amount of the obtained molded product were measured. The density distribution is
The polyurethane foam molded product was sliced to a thickness of 5 mm, the density of each section was measured, and the density was determined from the difference between the maximum value and the minimum value. The heat distortion temperature was measured according to JIS K6301. As for the amount of dust, a small vacuum cleaner (Matsushita Electric Hand Cleaner HC-V12; suction power 38 W) was installed at a location 300 mm away from the cutting edge of the flat end mill of the NC milling machine, and a specified cutting length was machined before and after cutting. It was determined from the change in weight of the dust bag. The cutting conditions on the NC milling machine at this time are as follows. NC milling machine type: Kikugawa Iron Works CNC router NCE-23-1F Bit type: Flat end mill (Φ
20, HSS) Processing conditions: 3000 rpm (rotation speed): 2000 mm / min (feed rate): 0.2 mm (cut amount): 120 mm x 5 reciprocations (total cutting length 1200 mm)

Example 2 Aromatic ring-containing polyol (III) 20 having a molecular weight of 286 obtained by addition-polymerizing 58 parts of PO to 228 parts of bisphenol A 20
Part, 290 parts of propylene glycol, and 290 parts of PO were added to polymerize aliphatic polyol (IV) 80 having a molecular weight of 366.
, Calcium chloride 5 parts, silicone SH-195 (foam stabilizer by Toresicone Co.) 4 parts, a prepolymer synthesized from TDI-80 (TDI made by Mitsui Nisso Urethane) and castor oil (NCO content 31) %,
VII) 81 parts were added, and a foamed polyurethane molded product was prepared in the same manner as in Example 1.

Example 3 To 228 parts of bisphenol A, 160 parts of a mixture of PO and EO in a weight ratio of 2: 1 was added and polymerized, 10 parts of an aromatic ring-containing polyol (V) having a molecular weight of 388, and to glycerin of 92 parts, 464 parts of PO was added. 90 parts of polymerized aliphatic polyol (VI) having a molecular weight of 556, 3 parts of hemihydrate gypsum, silicone SZ
To a premix consisting of 2 parts of -1627 (a foam stabilizer manufactured by Nippon Unicar), 75 parts of Coronate 1107 (crude MDI manufactured by Nippon Polyurethane Industry, NCO content: 31%) was added, and a foamed polyurethane molded product was produced in the same manner as in Example 1. It was created.

Example 4 An aromatic ring-containing polyol (VII) having a molecular weight of 460 obtained by adding 232 parts of PO to 228 parts of bisphenol A was added to 3 parts of
0 parts, 70 parts of the aliphatic polyol (II) of Example 1, 3 parts of barium hydroxide, 4 parts of silicone L-5420 (silicone foam stabilizer manufactured by Nippon Unicar), 89 parts of millionate MR-100 Example 1
A foamed polyurethane molded article was prepared in the same manner as in the above.

Example 5 200 parts of bisphenol F was added and polymerized with 146 parts of a mixture of PO and EO at a weight ratio of 1: 2, 30 parts of a polyol (VIII) containing a polyaromatic ring having a molecular weight of 346, and 377 parts of PO were contained in 185 parts of methyl glycoside. Has a molecular weight of 56 obtained by addition polymerization of
70 parts of 2 aliphatic polyol (IX), 4 calcium chloride
Parts, glass micro balloon C-15 (glass hollow body manufactured by Sumitomo 3M), 3 parts of silicone SH-193
143 L of millionate (modified MDI manufactured by Nippon Polyurethane Industry, NCO content 29%)
A polyurethane foam molded product was prepared in the same manner as in Example 1 except that 101 parts were added.

Example 6 20 parts of an aromatic ring-containing polyol (X) having a molecular weight of 400, wherein 172 parts of PO was added to 228 parts of bisphenol A, and 308 parts of PO was added to 92 parts of glycerin, and a molecular weight of 4 was added.
No. 00 aliphatic polyol (XI) 80 parts, molecular sieve 3A powder 2 parts, phenolic microballoon BJO-0930 (union carbide company hollow body) 1
To a premix consisting of 5 parts and 3 parts of silicone L-5420, 98 parts of Millionate MR-200 was added, and a foamed polyurethane molded article was prepared in the same manner as in Example 1.

Example 7 20 parts of the aromatic ring-containing polyol (I) of Example 1 and 92 parts of glycerin were added and polymerized with 282 parts of EO to give a molecular weight of 37.
80 parts of aliphatic polyol (XII) of 4, 4 parts of hemihydrate gypsum,
To a premix consisting of 5 parts of Matsumoto Microsphere MFL80ED (hollow body manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.) and 3 parts of silicone SZ-1627, 105 parts of Millionate MR-100 was added, and a foamed polyurethane molded product was produced in the same manner as in Example 1. It was created.

Comparative Examples 1 to 5 Comparative Example 1 was the same as Example 1 except that the polyol component was only the aliphatic polyol (II). Further, the weight ratio of the aromatic ring-containing polyol (I) to the aliphatic polyol (II) is set to 60.
Comparative Example 2 was changed to / 40. Example 1
Comparative Example 3 was prepared by removing the dehydrating agent (calcium sulfate). Furthermore, the aromatic ring-containing polyol (I) of Example 1 was changed to castor oil as Comparative Example 4, and the 3,3′-dichloro-4,4′-diaminodiphenylmethane was changed to Comparative Example 5, respectively. A foamed polyurethane molded article was prepared in the same manner as in Example 1. The amount of millionate MR-200 (B) used in this comparative example is 1: 1.04 in the equivalent ratio of the hydroxyl group of the polyol component (A) to the isocyanate group of (B) in each comparative example. Was set. Examples 1 to 7 and Comparative Examples 1 to 5
The performance of the molded product is shown in Table 1.

The density distributions of Examples 1 to 7 (difference between maximum and minimum values of density) are all 0.1 g / cm 3 or less, which is smaller than that of Comparative Examples 1 to 3. As in Comparative Example 1, only the aliphatic polyol increases the amount of dust. When the amount of the aromatic ring-containing polyol is large as in Comparative Example 2, the heat distortion temperature is low and the heat resistance is poor. When there is no dehydrating agent as in Comparative Example 3,
Bubbling occurs due to water and the density distribution increases. In Comparative Examples 4 and 5, the heat distortion temperature is low and the amount of dust is large.

[0041]

[Table 1]

[0042]

According to the present invention, dust during cutting can be reduced without lowering heat resistance, so that the working environment can be improved. Furthermore, since it is possible to obtain a lightweight polyurethane foam product having a uniform density distribution, it is possible to significantly reduce warpage deformation during cutting. Therefore, it is extremely useful for uses such as model materials.

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Claims (4)

(57) [Claims] 1. An aromatic ring-containing polyol (a) having a hydroxyl value of 200 to 400 represented by the following general formula and an aliphatic polyol (b) having a hydroxyl value of 250 to 500:
Tona is, the weight ratio of (a) and (b) is 10 / 90-40
/ 60, a polyol component (A), an aromatic polyisocyanate component (B), and the polyol component (A)
1-8 parts by weight of dehydrating agent per 100 parts by weight of (C), originating
A method for producing a foamed polyurethane molded article, which comprises foaming by a mechanical floss method without using a foaming agent . (In the formula, X is a group of any one of H, CH3, Cl, and Br;
-Y- is -CH2-, -C (CH3) 2-, -SO2.
-, -O-, or a single bond group; A is a propylene group or an ethylene group; m + n is a number from 0 to 13. ) (2 ) The hydroxyl value of (a) is from 250 to 3
50 and the hydroxyl value of the (b) is from 250 to
The process for producing a foamed polyurethane molded product according to claim 1 , wherein the ratio is 450 . 3. The process for producing a foamed polyurethane molded product according to claim 1, wherein said (b) is an alkylene oxide adduct of a divalent or tetravalent aliphatic or alicyclic alcohol. 4. The method for producing a foamed polyurethane molded article according to claim 1, further comprising 2 to 20 parts by weight of the hollow body (D) with respect to 100 parts by weight of the polyol component (A).