JPS6324524B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a polyurethane resin molded product that is foam-molded in a closed mold, and its objectives are to have excellent light stability, good dimensional stability, and high mechanical strength, and to prevent defects such as surface bubbles and pinholes during manufacturing. The aim is to obtain an integrally skind polyurethane foam that is free of oxidation. Polyurethane resin molded products that are foam-molded in a closed mold are generally called integral skinned foams, and when viewed in cross section, they have thick skin layers on both sides and only the inside is foamed. It has a so-called Sandermanch structure. Because of this sandwich structure, the rigid integral skinned foam has a bending strength and elastic modulus per unit weight that are significantly greater than those without a skin layer, and therefore can be used as structural members, such as furniture, etc.
It is being put into practical use as a building material or as a part for vehicles. Hard integral skin foams are often large, thick molded products, and require dimensional stability and surface beauty. If the dimensional changes are large, the seams with other parts may not match, and warping is likely to occur. To do this, conventionally it was necessary to insert metal parts or perform insert molding. In addition, the beauty of the surface is obtained by faithfully inverting the mold surface, but defects such as pinholes and surface bubbles (blisters) are likely to occur, especially in areas where the foam contacts the upper mold surface. Easy to occur. Until now, it has been extremely difficult to prevent pinholes, blisters, etc., and usually only one side of these molded products is visible as the product side, and the part that touches the upper mold side is used as the back side so that it is not visible to the public. It is difficult to apply this method to target products that require the use of a product as a product surface. Furthermore, these molded products have the disadvantage that when left exposed to the atmosphere, the surface of the molded product changes color and yellows, mainly due to ultraviolet rays and heat. For this reason, the surface of the molded product is generally coated with a highly weather-resistant paint, or a separately formed skin is placed on the surface of the mold and then foam-molded to prevent it from coming into direct contact with the atmosphere. However, when painting a molded product, the mold release agent on the surface of the molded product must be cleaned with a solvent, dried, and then painted.
Curing this requires many steps and equipment, such as hot air drying. Furthermore, painting work requires precise skill, which leads to a significant increase in costs and a strong demand for construction methods that do not require painting. The present invention was made in view of the above circumstances, and relates to an integral skind polyurethane resin molded product that is foam-molded in a closed mold. The object of the present invention is to provide a product that does not exhibit defective phenomena such as these on the entire front and back surfaces of a molded product, has a hard surface, has good dimensional stability, and has excellent mechanical strength. That is, the present invention provides a method for producing a rigid polyurethane foam molded product in which a polyol component and a polyfunctional isocyanate component are reacted and molded in a closed mold in the presence of a catalyst, a foam stabilizer, a blowing agent, and a pigment.
50 to 90 parts by weight of sucrose polyether and polyoxyalkylene glycol of ethylenediamine
50 to 10 parts by weight, and its average OH value is
A polyol component existing in the range of 480 to 610 is used, and the following general formula is used as a foam stabilizer. However, Me: methyl group, R: alkyl group represented by 1 to 4 carbon atoms, Z: -(CH ₂ ) _l - (OC ₂ H ₄ ) _n -
(OC ₃ H ₆ ) _o - OR x/y=8~15, Z component content 70~80%, l=0~4, m/n=2/3~
1. A polysiloxane-polyoxyalkylene glycol block copolymer with an average molecular weight of 10,000 to 20,000 represented by n + m = 33 to 60 per 100 parts by weight of the polyol component,
It is characterized in that 0.5 to 2 parts by weight is used and a non-halogen low boiling point solvent is used as the blowing agent. The sucrose polyether referred to in the present invention is obtained by adding alkylene oxide to sugar. In this manufacturing process, in order to reduce the viscosity of the sugar, the sugar is dissolved in water, diols such as polyoxypropylene glycol, polyoxypropylene-polyoxyethylene glycol, or triols such as trimethylolpropane and glycerin, and then dissolved in caustic potash or Since propylene oxide is addition-polymerized using a basic catalyst such as an alkali metal, the above-mentioned polyethers may be included in the sucrose-based polyether. Even in this case, the amount of diol added should be within the range of 15% by weight or less based on the total polyol; exceeding this is not preferable since dimensional stability tends to deteriorate and surface hardness tends to decrease. Next, the polyoxyalkylene glycol of ethylenediamine as used in the present invention can be obtained by addition polymerizing ethylenediamine with an alkylene oxide such as propylene oxide. In this case, the polyol mixture of the polyoxyalkylene glycol adduct of sucrose-based polyether and ethylenediamine as used in the present invention can also be produced by a one-step method of dissolving the above-mentioned sugar in ethylenediamine and then addition-polymerizing the alkylene oxide. In the present invention, sucrose-based polyether and polyoxyalkylene glycol of ethylenediamine are blended to 50 to 90 parts by weight of the former and 50 to 90 parts by weight of the latter.
The reason for the 10 parts by weight is mechanical strength, dimensional stability,
This is because the light resistance is within a well-balanced range. That is, the mechanical strength, especially the bending strength of the above-mentioned mixed polyol, is higher than the arithmetic average of the bending strengths of the sucrose-based polyether and the polyoxyalkylene glycol of ethylenediamine in the above-mentioned mixing ratio range, and the dimensions Stability also shows good values. Furthermore, the addition of polyoxyalkylene glycol of ethylene diamine to sucrose-based polyether has the advantage that the light resistance is improved compared to sucrose-based polyether alone. In addition, the average OH value of the polyol component is 480 to 610
is preferable; if the OH number is less than 480, the surface hardness of the molded product will be too low, and if it exceeds 610, the mechanical strength will deteriorate. Another feature of the present invention is that the foam stabilizer has an alkoxy group (- in Z) as shown in the general formula above.
A polysiloxane-polyoxyalkylene glycol block copolymer produced by addition polymerization of ethylene-propylene oxide with a molecular weight of
10,000 to 20,000 are used. A particularly preferred range of molecular weight is 14,000 to 18,000. If the molecular weight is less than 10,000, the fluidity of the foam stock solution will be poor, while if it exceeds 20,000, the compatibility between the polyol component and the polyfunctional isocyanate component will decrease, leading to the risk of non-uniform foaming. The formula for x and y in the formula is preferably in the range of x/y = 8 to 15. If it exceeds 15, the size of the foamed cells will become uneven, causing cell roughness, and conversely, if it is less than 8, it will be difficult to seal. As the liquid injected into the mold flows, it has poor wettability with the mold and tends to trap air. Particularly preferred is a range of x/y=10 to 12. If the Z content is less than 70%, the fluidity of the reaction mixture will be poor, and if it exceeds 80%, the compatibility will be poor. A particularly preferred range is 74% to 76%. On the other hand, the reason why l in Z is set to 1 to 4 is that compounds in this range are easy to synthesize. Particularly advantageous is l=3. In addition, m/n = 2/3 to 1 was selected because if it is less than 2/3, the bubbles will easily collapse during the flow of the liquid injected into the closed mold, and if it exceeds 1, the bubbles will be coarse when being injected. This is because it becomes difficult for air bubbles to come out. The most effective value is around m/n=45/55. The reason for setting m+n=33 to 60 is that if it is less than 33, the fluidity of the reaction mixture will be poor, whereas if it exceeds 60, the foamed cells will not only become extremely large but also become non-uniform. Particularly preferred is m+n
= around 50. Furthermore, R represents an alkyl group, especially a carbon number of 1 to 4.
The reason for choosing this alkyl group is that compared to the conventional one with an OH group, the uniformity of the foamed cells and the absence of pinholes on the surface of the molded product significantly improve the surface smoothness. Also, the alkyl group is 2
It may be more than a species. The molecular weight for rigid foams is generally small;
x/y is small (0.1~5) m/n is large (1
~9), many of which have a hydroxyl group at the end. For semi-rigid foams, foam stabilizers are used that are intermediate between those for soft foams and hard foams. The foam stabilizer used in the hard integral skin urethane foam of the present invention is particularly effective against defects such as surface bubbles and pinholes when a non-halogen foaming agent is used, and is superior to conventional general foaming agents. In the case of halogen-based materials, the present invention is not effective. The polyfunctional isocyanate used in the present invention is not particularly limited, and conventionally used ones such as diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), and xylene diisocyanate (XDI) can be used as they are. However, in terms of reactivity and toxicity, MDI systems such as crude MDI, pure MDI prepolymer, and carbodiimidated MDI are suitable. Further, the reaction catalyst used in the present invention is not particularly limited, and all conventional catalysts can be used. Typical examples include tertiary amines such as dimethylaminoethanol and triethylenediamine, and organometallic compounds such as dibutyltin dilaurate. The pigment used in the present invention is not particularly limited, but is usually an inorganic pigment with good light resistance, such as titanium oxide or red iron oxide, which has been kneaded with polyol in an amount of 40 to 70%. When making a product without painting, if the amount of pigment added is small, color unevenness is likely to be noticeable, so 1 to 1
It is recommended to use about 5%. The present inventors discovered and proposed that the light resistance of the polyol can be significantly improved by using a specific non-halogenated low-boiling solvent that has not been used as a blowing agent for polyurethane. Hard integral foams generally have poorer light resistance than soft integral foams. This is thought to be due to the high content of polyfunctional isocyanate, which is the main cause of yellowing, and the fact that the blowing agent remains in the skin layer indefinitely with almost no volatilization. This is because the soft integral foam loses a lot of weight immediately after molding, and most of the foaming agent evaporates in about 10 hours, resulting in a 1-5% dimensional shrinkage, whereas the hard integral foam This is inferred from the fact that there is almost no change in weight over time over several months. That is, the well-known Freon 11, which has been conventionally used as a blowing agent for polyurethane foam,
113, halogenated solvents such as methylene chloride remain in the skin layer of hard integral foam, decompose under ultraviolet rays and heat, generate chlorine and radicals, and are thought to promote yellowing. Among polyols, diaminodiphenylmethane and tolylene diamine polyethers have poor light resistance even when non-halogenated solvents are used, and the polyol in the present invention has the best light resistance. As the non-halogenated low boiling point solvent which is the third feature of the present invention, one or more selected from pentane, hexane, heptane, petroleum ether, acetone, tetrahydrofuran, propylene oxide, methyl acetate, and methyl formate is used. The amount used is preferably 3 to 30 parts by weight per 100 parts by weight of the polyol component. As a blowing agent, it is okay to use a chemical blowing agent that reacts with isocyanate, such as water, to generate carbon dioxide gas, but when using a chemical blowing agent, the amount is 1 weight per 100 parts by weight of the polyol component. If the amount is more than that, the skin layer will foam, making it difficult to form a sandwich structure. In order to evaluate the light resistance in the present invention, the test piece was subjected to an accelerated light resistance test using a fade meter (carbon arc) with a black panel temperature of 63°C, and the tristimulus values X, Y, and Z of the color before and after the test were measured, and the Hunter color difference was measured. It was determined using the calculation formula. Color measurement is done using direct reading colorimetry color difference computer CDE-SCH-4A (Suga Test Instruments)
This was done using Note that Hunter's color difference ΔE (Lab) is expressed by the following formula, and the smaller the value of the color difference ΔE (Lab), the better the light resistance is, and if ΔE = 3 or less, discoloration is usually not noticeable. △E(Lab) =√(△) ² +(△) ² +(△) ² L=10√ a=17.5(1.02X-Y)/√ b=7.0(Y-0.847Z)/√ △E( Lab): Hunter color difference △L: Difference in lightness index before and after the test △a, △b: Difference in color perception index before and after the test
The E value was used as a standard for light resistance evaluation. The rate of dimensional change during physical property evaluation in the present invention is measured at −20°C after demolding of the hard integral skinned foam.
The dimensions are measured after 4 cycles of a cold/hot cycle test where one cycle is 2 hours at 60°C and 2 hours at 60°C, and the difference from the mold dimension is divided by the mold dimension. It is the sum of the thermal contraction rate and the cold shrinkage rate. According to the invention, in particular by using the novel polyol component, foam stabilizer and blowing agent described above,
Defects such as surface bubbles and pinholes during manufacturing do not occur over the entire surface of the product, and an integral skind polyurethane resin molded product with excellent light stability can be obtained without painting the product. Therefore, polyether alone or in combination with known diols or triols,
If a foam stabilizer made of an organic silicone block copolymer such as that used in ordinary rigid urethane foams is used, the object of the present invention cannot be achieved. The present invention will be explained in more detail below using conventional examples, comparative examples, and examples. Conventional Examples 1 to 2 100 parts by weight of the polyol components shown in Table 1, 5 parts of pigment (60% by weight contained in polypropylene glycol with Mw = 3000) as a blowing agent, and a 20% dimethylaminoethanol solution of triethylenediamine as a catalyst 3
The foam stabilizer is a polysiloxane-polyoxyalkylene glycol block copolymer (in the general formula, x/y=2.7Z content: 60%, m/n
=3/1, m+n=8, terminal group OH, OH value 76,
1 part of molecular weight 4800) was mixed in advance into RIM machine A tank, then the polyfunctional isocyanate shown in Table 1 was similarly put into B tank, and after low pressure circulation, A
The mixture was shot from the mixing head through a gate into a mold having an internal volume of 800 x 300 x 10 mm at a pressure of 100 kg/cm ² for liquid and 80 kg/cm ² for liquid B. Mold temperature is 40
The specific gravity of the molded plate was set to 0.4 at °C. The blending ratio of polyol component and polyfunctional isocyanate is NCO/OH=
It was set to 1.05. Examples 1 to 2 A sucrose-based polyether with an OH value of 550 made by adding propylene oxide to sugar as a polyol component (sugar contains 10% by weight of glycerin to adjust the viscosity, the same applies hereinafter) and propylene oxide added to ethylenediamine. It becomes
A polyether with an OH value of 767 was mixed in the proportions shown in Table 1, a blowing agent shown in Table 1 was used, 5 parts of the pigment, and 3 parts of a 20% diethylaminoethanol solution of triethylenediamine as the catalyst. section was used. The foam stabilizer is a polysiloxane-polyoxyalkylene glycol block copolymer having a methyl group as R in Z in the above general formula (x/y=10, Z content 75%, l=3, m/n
=45/55, m+n=49, molecular weight 15000) 1 part, n-pentane, which is a non-halogen hydrocarbon solvent, as a blowing agent, and water were used in the amounts shown in Table 1. The above components were mixed and put into RIM machine A tank, then crude MDI was similarly put into B tank, circulated under low pressure, and shot under the same conditions as in Conventional Example 1 to obtain a molded plate. When viewed in cross section, it had a sandwich structure with a 1mm skin layer on both sides. Comparative Examples 1 to 10 Using the polyether shown in Table 1, which is made by adding propylene oxide to various amines or polyhydric alcohols, as the polyol component, each component was mixed according to the same procedure as in the example, and then mixed using a RIM machine. A molded plate was obtained. Table 1 shows the properties of the hard integral skinned foam molded plates obtained in Conventional Examples 1 and 2, Examples 1 and 2, and Comparative Examples 1 and 10. From Table 1, halogenated solvent (Freon 11) is used as a blowing agent.
When using (Conventional Examples 1 and 2), ΔE=30 or more, resulting in a significant deterioration in light resistance. On the other hand, when a non-halogen foaming agent (n-pentane) is used as the foaming agent and a new polyol component is used (Examples 1 and 2) as in the product of the present invention, the light resistance is △E = 3.0 or less. Discoloration becomes less noticeable. Examples 1 and 2
Comparative Examples 1 and 2 have high bending strength, small dimensional change, and light resistance of △E=3 or less, which is overall satisfactory, whereas Comparative Examples 1 and 2 have high bending strength but △E=
If it is 15 or higher, the light resistance is very poor. Example 2 is a combination of the polyols of Comparative Examples 5 and 7, and the bending strength shows a value larger than the arithmetic average value of each, indicating that there is a synergistic effect. On the other hand, as seen in Comparative Examples 8 to 10, in combinations of polyols containing sucrose as one component, which has excellent bending strength and weather resistance, the bending strength is the average value of each or a value worse than that. It can be seen that the product of the present invention has excellent mechanical strength and weather resistance.

【table】

[Table] Comparative Examples 11 to 12 and Examples 3 to 9 A hard integra was prepared in the same manner as in Example 2 using 70 parts of sucrose polyether having the OH value shown in Table 2 and 30 parts of polyoxypropylene glycol of ethylenediamine. Manufactures Ruskind foam. These characteristics are shown in Table 2.

【table】

[Table] From Table 2, it can be seen that the preferable average OH value range for various physical properties for all polyols is 480 to 610. Comparative Examples 13-14, Examples 10-14 Sucrose-based polyether with an OH value of 450 and OH
A hard integral skind foam molded plate was obtained in the same manner as in Example 2 using ethylene diamine and polyoxypropylene glycol having a value of 767. The results are shown in Table 3.

Table 3 shows that the composition ratio of sucrose polyether and polyoxypropylene glycol of ethylenediamine is 50 to 90 parts by weight for the former and 50 to 10 parts by weight for the latter, which are excellent in various properties. In particular, it can be seen that the bending strength reaches its maximum value at a composition ratio of 70/30. Comparative Examples 15 to 17 and Examples 15 to 24 Using 70 parts by weight of sucrose polyether with an OH value of 450 and 30 parts by weight of polyoxypropylene glycol of ethylenediamine with an OH value of 767, Table 4
A rigid integral skin foam molded plate was prepared in the same manner as in Example 2 by blending the blowing agent shown in , and was subjected to a light resistance test. It can be seen from Table 3 that the blowing agents used in Example 2 and Examples 15-23 have significantly improved light resistance compared to the halogen-based blowing agents used in Examples 15-19. It is also understood that the foaming agent may be used in combination with water or in combination of two or more.

【table】

[Table] Comparative Examples 22 to 28 and Examples 26 to 35 70 parts by weight of sucrose polyether with an OH value of 450 and 30 parts by weight of polyoxypropylene glycol of ethylenediamine with an OH value of 767 were used as the polyol components, and n as the blowing agent. -Pentane
10 parts by weight, 20 parts of triethylenediamine as catalyst
% dimethylaminoethanol solution, 0.1 part of dibutyltin dilaurate, and 5 parts of pigment, and as a foam stabilizer, a chemical composition as shown in Table 4 in the above general formula (where R is a methyl group and l = 3) was used. The obtained polysiloxane-polyalkylene glycol block copolymer was mixed in advance in the amounts shown in Table 4, and crude was prepared as a polyfunctional isocyanate.
A hard integral skinned foam molded plate was prepared in the same manner as in the previous example so that the MDI was NCO/OH = 1.05. Table 4 shows the observation results of the condition of the sample (defective phenomenon) and the dimensional change rate.

[Table] From Table 4, polysiloxane polyoxyalkylene glycol block copolymers having various chemical compositions in the above general formula (where R is a methyl group and l=3) as foam stabilizers are used within the scope of this example. It can be seen that some of the integral skinned foams have no air entrainment or cell roughness, and no air bubbles are formed on the surface. Comparative Examples 29 to 30 and Examples 35 to 39 As a foam stabilizer, the same chemical composition as in Example 27 was used, except that OR in Z in the general formula above was an alkyl group or -OH group shown in Table 5, or a mixture. A rigid integral skin foam molded plate was prepared under the same conditions using the polysiloxane-polyoxyalkylene block copolymer. Table 5 shows the surface condition and dimensional change rate of the sample.

【table】

[Table] From Table 5, the surface condition of the foam deteriorated when OR in Z contained -OH groups. In addition, those having a carbon number of C ₁ to C ₄ were good, and the combination of C ₂ and C ₄ had the best surface condition.

Claims (1)

[Scope of Claims] 1. A method for producing a rigid polyurethane foam molded product in which a polyol component and a polyfunctional isocyanate component are reacted and molded in a closed mold in the presence of a catalyst, a foam stabilizer, a blowing agent, and a pigment. A polyol component consisting of 50 to 90 parts by weight of polyether and 50 to 10 parts by weight of polyoxyalkylene glycol of ethylenediamine and having an average OH value in the range of 480 to 610 is used, and the following foam stabilizer is used. general formula However, (Me: methyl group, R: alkyl group represented by 1 to 4 carbon atoms, Z: -(CH ₂ ) _e - (OC ₂ H ₄ ) _n -
(OC ₃ H ₆ ) _o - OR x/y=8~15, Z component content
70-80%, l=0-4, m/n=2/3-1, n
+m=33-60) A polysiloxane-polyoxyalkylene glycol block copolymer having an average molecular weight of 10,000-20,000 was added at 0.5 parts per 100 parts by weight of the polyol component.
2 parts by weight and a non-halogenated low boiling point solvent as a blowing agent. 2 The non-halogenated low boiling point solvent is n-pentane, n
- The method for producing a rigid urethane foam molded article according to claim 1, wherein the molded product is selected from among hexane, n-heptane, petroleum ether, acetone, tetrahydrofuran, propylene oxide, methyl acetate, and methyl formate.