JP4301432B2 - Method for producing polyurethane foam molded article - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a semi-rigid or flexible polyurethane foam molded article having an integral skin layer on the surface.
[0002]
[Prior art]
As a conventional method for producing a semi-rigid or flexible polyurethane foam molded article having an integral skin layer, a polyol composition containing a polyol compound, a foaming agent and the like and a polyisocyanate component are mixed and stirred in a foaming machine, and a reaction stock solution composition A method of injecting into a mold and foaming and curing to form a molded product is used, and the following techniques are known as polyol compositions.
(1) Technology using as a main component a polyol having a hydroxyl value of 30 to 85, a hydroxyl number of 2 to 8, a viscosity of 1000 cp or less at 25 ° C., and an overall oxyethylene group content of 20% by weight or less ( Patent Document 1)
(2) Technology using an amino group-containing polyol as a polyol composition (Patent Document 2)
(3) Technology for adding fatty acid methyl ester as a thickener to a polyol composition (Patent Document 3)
All of the above techniques use water as a blowing agent.
[0003]
[Patent Document 1]
JP 7-102036 A [Patent Document 2]
JP-A-5-339338 [Patent Document 3]
Japanese Patent No. 3242755 [Problems to be Solved by the Invention]
Conventionally, as a foaming agent for polyurethane foam having an integral skin, HCFC-141b, which is an alternative chlorofluorocarbon, is used like other polyurethane foams. From the viewpoint of environmental protection, a manufacturing method using water as a foaming agent Is requested.
[0004]
All the methods for producing a polyurethane foam having an integral skin described in Patent Documents 1 to 3 use water as a foaming agent.
[0005]
However, according to the techniques described in Patent Documents 1 and 2, the viscosity of a polyol composition containing water as a foaming agent is high, and it is also described in Examples in order to sufficiently mix with a polyisocyanate component. It is necessary to use a high pressure foaming machine. In the conventional production method using a polyol composition using HCFC-141b as a foaming agent, a low-pressure foaming machine is generally used because the viscosity of the polyol composition is not high. The polyol composition described in Patent Document 1 could not be used because of its high viscosity and poor mixing with the polyisocyanate component.
[0006]
In the technique described in Patent Document 3, fatty acid methyl ester is added as a thickening agent, the viscosity of the polyol composition is suppressed, and although consideration is given to odors, furniture used in a small room, etc. May cause problems such as odor.
[0007]
An object of the present invention is a case where it can be molded even if an existing low pressure foaming machine is used without renewing the manufacturing equipment to a high pressure foaming machine, and used for furniture used indoors. Another object of the present invention is to provide a method for producing a polyurethane foam molded article having an integral skin that does not cause odor problems.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors have intensively studied a polyol composition for a polyurethane foam having an integral skin. As a result, 100 parts by weight of a polyol compound constituting the polyol composition was converted into 2 having a molecular weight of 500 to 4000. By containing 70 to 95 parts by weight of a functional polyol compound and 30 to 5 parts by weight of a trifunctional or higher polyfunctional polyol, even if water is used as a foaming agent, it has a low viscosity without using a thinning agent. In order to complete the present invention, it is found that a polyol composition that can be mixed with a polyisocyanate component using a low-pressure foaming machine and forms a polyurethane foam with an integral skin having an unprecedented soft feel is obtained. It came.
[0009]
That is, in the method for producing a polyurethane foam molded article of the present invention, a reaction stock solution composition in which a polyol composition containing at least a polyol compound, a crosslinking agent, a catalyst, and a foaming agent and a polyisocyanate component are mixed is injected into a mold. A method for producing a polyurethane foam molded article having a molded body having an integral skin,
Wherein is the viscosity at 20 ° C. of the polyol compound is less 750 mPa · s, the polyol compound 100 parts by weight average bifunctional polyol compound having a molecular weight of 500 to 4,000 70 to 95 parts by weight and the average molecular weight 700-8000 of trifunctional or higher- 30 to 5 parts by weight of a functional polyol, the foaming agent is water, and the surface hardness of the molded body is 45 degrees or less with an Asker C hardness meter.
[0010]
When the amount of the bifunctional polyol compound having a molecular weight of 500 to 4000 (end group determination method) is less than 70 parts by weight, the ratio of the trifunctional or higher polyfunctional polyol compound is increased and the viscosity of the polyol composition is increased. On the other hand, when the amount exceeds 95 parts by weight, the polyfunctional component becomes too small, causing problems such as a decrease in compression set.
[0011]
When the molecular weight of the bifunctional polyol compound is less than 500, the soft feel of the resulting polyurethane foam molded article may be impaired. When the molecular weight exceeds 4000, the viscosity of the polyol composition increases, the mechanical properties of the polyurethane foam molded article Problems such as a decrease in strength may occur. The average molecular weight of the bifunctional polyol compound is more preferably 700 to 3000.
[0012]
The density of the polyurethane foam molded article having an integral skin obtained by the production method of the present invention is preferably 0.2 to 0.4 g / cm ³ .
[0013]
In the above method for producing a polyurethane foam molded article, it is preferable to inject the reaction stock solution composition after forming a coating film on the mold surface.
[0014]
With such a configuration, it is possible to produce a polyurethane foam molded article having an arbitrary color tone and an excellent appearance, and having excellent weather resistance.
[0015]
In the above-mentioned invention, the polyisocyanate component is preferably a prepolymer-containing polyisocyanate compound or a carbodiimide-modified polyisocyanate compound.
[0016]
By using such a polyisocyanate component, it is possible to obtain a polyurethane foam with an integral skin having a surface hardness of a molded body of 45 degrees or less with an Asker C hardness meter, excellent physical properties, and particularly a tensile strength of 1.0 MPa or more. Can do.
[0018]
By setting the viscosity at 20 ° C. to 750 mPa · s or less, it is possible to reliably use an existing foaming machine. The viscosity of the polyol composition at 20 ° C. is more preferably 700 mPa · s or less.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The polyol compound used in the present invention is generally a polyfunctional alcohol compound, an alkanolamine compound, a bifunctional or higher primary or secondary amino compound as an initiator, and so-called alkylene oxide added thereto. Polyether polyols are used.
[0020]
Examples of the polyfunctional alcohol compound and alkanolamine compound include water, ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, Examples include ethanolamine, diethanolamine, and compounds obtained by adding a small amount of alkylene oxide to these. Examples of the bifunctional or higher primary or secondary amino compound include ethylenediamine, propylenediamine, and toluenediamine.
[0021]
Among these, as a raw material of a polyol compound which is a bifunctional polyol compound having an average molecular weight (according to a terminal group determination method) of 500 to 4000, ethylene glycol, propylene glycol, water, 1,4-butanediol, 1,6- Bifunctional alcohol compounds such as hexanediol and neopentyl glycol are used. More preferably, the bifunctional polyol compound does not contain an amino group.
[0022]
Trifunctional or higher polyfunctional alcohol compounds such as glycerin, trimethylolpropane, pentaerythritol, triethanolamine and diethanolamine, alkanolamine compounds, bifunctional or higher primary or secondary amino compounds are trifunctional or higher functional groups. It is used as a raw material for polyfunctional polyol compounds. The average molecular weight of the polyfunctional polyol compound is preferably 700 to 8000. It is more preferable that the polyfunctional polyol compound has an average functional group number of 3 to 4 and does not contain an amino group from the viewpoint of reducing the viscosity of the polyol composition. However, a small amount of an amino group-containing polyol compound may be used in order to adjust the reactivity and physical properties of the molded product within the range not impairing the object of the present invention.
[0023]
Examples of the alkylene oxide for addition polymerization to a polyfunctional alcohol compound and the like to produce a polyol compound include those having 2 or more carbon atoms, such as ethylene oxide, 1,2-propylene oxide, and 1,2-butylene oxide. 2,3-butylene oxide, styrene oxide and the like. Among these alkylene oxides, those in which propylene oxide and / or butylene oxide and ethylene oxide are used in combination are preferable because of low cost and good characteristics of the resulting polyurethane foam molded product with integral skin. In particular, those containing an ethylene oxide unit in which ethylene oxide is a ring-opening unit in an addition ratio of 3 to 50% by weight, more preferably 3 to 25% by weight are preferable.
[0024]
The polyol compound may be either a random polymer or a block polymer of the alkylene oxide, but those containing an oxyethylene unit at the terminal are preferable because of good reactivity with an isocyanate group. The terminal primary ratio (terminal ethylene oxide unitization ratio) is preferably 3% by weight or more, more preferably 5% by weight or more, and particularly preferably 10 to 20% of the oxyalkylene unit of the polyoxyalkylene glycol. % By weight.
[0025]
As the polyisocyanate compound, various aromatic, alicyclic and aliphatic polyisocyanate compounds having two or more isocyanate groups, which are usually used in the production of polyurethane foam molded products with integral skin, A modified polyisocyanate compound obtained by modifying these polyisocyanate compounds can be used. Two or more polyisocyanate compounds may be used in combination.
[0026]
Specific examples of the polyisocyanate compound include diphenylmethane diisocyanate (MDI) (purified diphenylmethane diisocyanate (p-MDI) and crude MDI (c-MDI)), xylylene diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. Examples of modified products include prepolymer-containing polyisocyanate compounds (prepolymer modified products of polyisocyanate compounds), isocyanurate modified products, urea modified products, and carbodiimide modified products. Toluene diisocyanate has a 2,4-substituted product and a 2,6-substituted product, and the use of a mixture of these is preferred, and the 2,4-substituted / 2,6-substituted product mixture ratio is 90 / 10-10. The use of a 60/40 mixture is preferred. It is also possible to use an isocyanate compound obtained by blending toluene diisocyanate and crude MDI.
[0027]
In the present invention, it is preferable to use a prepolymer-modified polyisocyanate compound (including a urethane bond) or a carbodiimide-modified polyisocyanate compound (including a carbodiimide bond or a uretonimine bond). Preparation of the prepolymer-modified polyisocyanate compound is generally carried out by adding a prepolymer having an isocyanate group terminal to the isocyanate component. Preferred isocyanate group-terminated prepolymers are difunctional to trifunctional, more preferably bifunctional, having a molecular weight of 500 to 5000 and an NCO / OH equivalent ratio of 1.5 to 2.5, more preferably Is obtained by heating reaction at 1.8 to 2.0.
[0028]
An isocyanate compound containing an isocyanate group-terminated prepolymer may be produced by synthesizing an isocyanate group-terminated prepolymer and mixing it with a commercially available isocyanate compound, or mixing a commercially available isocyanate group-terminated prepolymer with a commercially available isocyanate compound. A predetermined amount of a polyol compound may be added to and reacted with a commercially available isocyanate compound, or a commercially available isocyanate compound containing an isocyanate group-terminated prepolymer may be used. Examples of the isocyanate compound containing a commercially available isocyanate group-terminated prepolymer include CE-501 (Nippon Polyurethane).
[0029]
The carbodiimide-modified polyisocyanate compound is produced by converting a part of the isocyanate group into a carbodiimide bond using a catalyst. As the carbodiimide-modified polyisocyanate compound, Cosmonate LL and Cosmonate LK (Mitsui Takeda Chemical) are commercially available and can be used.
[0030]
Urethane catalysts include triethylenediamine (TEDA, Dabco), bis (N, N-dimethylamino-2-ethyl) ether, N, N, N ′, N′-tetramethylhexamethylenediamine, bis (2-dimethyl). Examples thereof include amine catalysts such as aminoethyl) ether (TOYOCAT-ET; manufactured by Tosoh Corporation), carboxylic acid metal salts such as potassium acetate and potassium octylate, and organometallic compounds such as dibutyltin dilaurate. Among these, the use of an amine catalyst is preferable because it is suitable for the production of water-foamed polyurethane foam. The tertiary amine catalyst preferably uses a foaming catalyst and a resination catalyst in combination, and more preferably has a resinization catalyst / foaming catalyst weight ratio of 1 or more.
[0031]
In the production of a polyurethane foam molded article with an integral skin according to the present invention, it is also preferable to use a low molecular weight polyfunctional active hydrogen compound as a crosslinking agent as necessary. It becomes easy to adjust various characteristics of the polyurethane polymer to be formed, especially the rigidity of the polyurethane foam molded article. As such a low molecular weight polyfunctional active hydrogen compound, it is preferable to use a low molecular weight polyhydric alcohol or alkanolamine. Specifically, ethylene glycol, propylene glycol, 1,4-butanediol exemplified as a raw material of the polyol compound. 1,6-hexanediol, neopentyl glycol, glycerin, trimethylolpropane, pentaerythritol, triethanolamine, diethanolamine and the like are exemplified and usable. These compounds may be used alone or in combination of two or more. In particular, the combined use of glycol and alkanolamine is preferred from the standpoint that the strength of the molded article is increased and the elasticity is excellent.
[0032]
The amount of each component used in the polyurethane foam raw material containing the polyol compound, polyisocyanate component, foaming agent, catalyst, and, if necessary, a foam stabilizer is usually as follows. Needless to say, the amount used can be appropriately changed in order to adjust the characteristics.
[0033]
The equivalent ratio of the hydroxyl group of the polyol composition containing the polyol compound to the isocyanate group of the polyisocyanate component (isocyanate index [NCOindex]) is in the range of 0.75 to 1.15 (75 to 115 in the index display). Is preferable, and 0.8 to 1.1 (80 to 110 in the index display) is more preferable. The amount of water used as the blowing agent is usually 0.1 to 4 parts by weight, preferably 0.5 to 1.5 parts by weight, based on 100 parts by weight of the polyol compound. The amount of the catalyst used is usually 5 parts by weight or less, preferably 0.5 to 3.0 parts by weight, based on 100 parts by weight of the polyol compound. The amount of the foam stabilizer added as necessary is usually 5 parts by weight or less (based on the active ingredient in the case of a foam stabilizer diluted with a plasticizer, etc.) with respect to 100 parts by weight of the polyol compound. Preferably it is 0.01-2 weight part.
[0034]
The polyurethane foam raw material comprising the various components is converted into a polyurethane foam molded product with an integral skin in a predetermined mold corresponding to various shapes depending on the application to which the polyurethane foam molded product with an integral skin is applied. Molded. Usable means can be employed as the molding method. For example, after a predetermined amount of a polyol compound, a foaming agent, a catalyst, a foam stabilizer, a crosslinking agent and, if necessary, additives are preliminarily mixed to form a polyol composition, a polyisocyanate component is further added to the polyol composition which is this mixture. A polyurethane foam raw material obtained by rapid mixing using a polyurethane foaming machine or a stirrer is preferably poured into a mold that has been previously coated with a paint that constitutes the epidermis and then demolded after a predetermined time. As a result, a soft or semi-rigid polyurethane foam as a polyurethane foam molded article with an integral skin can be obtained.
[0035]
According to the present invention, it is possible to produce a polyurethane foam molded article with an integral skin using an existing low pressure foaming machine or high pressure foaming machine.
[0036]
【Example】
Examples and the like specifically showing the configuration and effects of the present invention will be described below.
Example 1
90 parts by weight of a bifunctional polyol compound (PPG type) having an average molecular weight of 3000 (hydroxyl value of 37 mgKOH / g), 10 parts by weight of a polyol compound having an average molecular weight of 5000 and a hydroxyl value of 34 mgKOH not containing an amino group as a trifunctional polyol compound, As a cross-linking agent, 4.5 parts by weight of an aliphatic low molecular weight glycol and 1.0 part by weight of diethanolamine. As a catalyst, 1.0 part by weight of TEDA L33E (Tosoh) and 0.5 part by weight of TOYOCAT ET (Tosoh), a foaming agent. A polyol composition was prepared by mixing 0.8 part by weight of water.
Using CE-501 (NCO = 22.5 wt%, Nippon Polyurethane) as the polyisocyanate component, low-pressure foaming so that the reaction stock solution composition of polyol composition / polyisocyanate component = 100 / 44.3 (weight ratio) A polyurethane foam molded article with an integral skin was prepared by using a machine and injecting it into a mold.
The obtained polyurethane foam molded article had a good appearance, its surface hardness was 40 degrees with an Asker C hardness meter, and the tensile strength was 1.0 MPa.
[0037]
(Example 2)
A polyurethane foam molded article with an integral skin was prepared in the same manner as in Example 1 except that 75 parts by weight of the bifunctional polyol compound and 25 parts by weight of the trifunctional polyol compound were used.
The obtained polyurethane foam molded article had good appearance, its surface hardness was 45 degrees with an Asker C hardness meter, and the tensile strength was 1.2 MPa.
[0038]
(Example 3)
80 parts by weight of a bifunctional polyol compound (PPG) having an average molecular weight of 3000 (hydroxyl value of 37 mgKOH / g) and 20 parts by weight of a polyol compound having an average molecular weight of 5000 (hydroxyl value of 34 mgKOH) not containing an amino group are used as the trifunctional polyol compound. , 5.0 parts by weight of aliphatic low molecular weight glycol and 0.5 parts by weight of diethanolamine as a crosslinking agent, 1.0 part by weight of TEDA L33E (Tosoh) and 0.5 parts by weight of TOYOCAT ET (Tosoh) as a catalyst, A polyol composition was prepared by mixing 0.5 parts by weight of certain water.
Cosmonate LL (NCO = 29.0 wt%, Mitsui Takeda Chemical) is used as the polyisocyanate component, and the reaction stock solution composition of polyol composition / polyisocyanate component = 100/45 (weight ratio) is used in a low pressure foaming machine. Then, it was poured into a mold to produce a polyurethane foam molded article with an integral skin.
The obtained polyurethane foam molded article had a good appearance, its surface hardness was 40 degrees with an Asker C hardness meter, and the tensile strength was 1.0 MPa.

Claims (3)

A polyurethane foam molded article in which a reaction stock solution composition obtained by mixing a polyol composition containing at least a polyol compound, a crosslinking agent, a catalyst, and a foaming agent and a polyisocyanate component is injected into a mold to form a molded article having an integral skin. A manufacturing method of
Wherein is the viscosity at 20 ° C. of the polyol compound is less 750 mPa · s, the polyol compound 100 parts by weight average bifunctional polyol compound having a molecular weight of 500 to 4,000 70 to 95 parts by weight and the average molecular weight 700-8000 of trifunctional or higher- A method for producing a polyurethane foam molded product comprising 30 to 5 parts by weight of a functional polyol, wherein the foaming agent is water, and the surface hardness of the molded product is 45 degrees or less with an Asker C hardness meter.  The method for producing a polyurethane foam molded article according to claim 1, wherein the reaction stock solution composition is injected after forming a coating film on the mold surface.  The method for producing a polyurethane foam molded article according to claim 1 or 2, wherein the polyisocyanate component is a prepolymer-containing polyisocyanate compound or a carbodiimide-modified polyisocyanate compound.