JPS5944914B2 - Molding method of polyurethane foam layer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention discloses the raw material solution composition of polyurethane foam to be additionally foamed when forming a polyurethane foam layer on the cut surface or cut surface of polyurethane foam by spray foaming, that is, the essential components of polyhydroxy compound and polyisocyanate. A urethane raw material liquid having a composition in which only the foaming agent in the raw material, foaming agent, foam stabilizer, flame retardant, catalyst, etc. is replaced with a mixture of appropriate amounts of multiple types of foaming agents with different boiling points, that is, foaming start temperatures, is prepared in advance. After forming a polyurethane foam layer by spraying onto the cut surface or cut surface, an additional layer of polyurethane foam of the same composition as the polyurethane foam to be additionally foamed is spray-foamed, and the polyurethane foam layer is spray-foamed. The present invention relates to a method of forming a polyurethane foam layer having good bond strength on a cut surface or cut surface of a foam.

Polyurethane foam is a thermosetting plastic foam, and among them, rigid polyurethane foam is widely used as an industrial heat insulating material due to its excellent heat insulating properties.

Regarding the construction methods when using polyurethane foam as a heat insulating material, there are two methods: one method is to bond a polyurethane foam material that has been formed into a predetermined shape to the part to be heat-insulated to form a heat-insulating layer, and the other is to connect the urethane raw material liquid composition directly to the part to be heat-insulated. A typical method is to form a polyurethane foam layer by spray foaming the polyurethane foam layer.

In particular, the spray foaming method is suitable for on-site implementation because it can be applied to any shape of the part to be heat-insulated, the thickness of the polyurethane foam layer can be easily adjusted, and workability is good. Therefore, it is often used for heat insulation construction of large structures.

When installing or repairing heat shielding materials for large structures, etc., it is often necessary to add a polyurethane foam layer and spray foam after removing all or part of the surface of the already applied polyurethane foam layer by cutting or cutting. There is.

As a typical example, the first step is to spray foam upwards (
If the polyurethane foam is formed in the foaming target area, the soft foam in the curing reaction process will tend to sag if the polyurethane foam is formed in the foaming target area. Since the surface of the formed polyurethane foam layer is extremely uneven, in order to obtain a uniform polyurethane foam layer, the entire surface or a part of the surface of the already foamed polyurethane foam layer must be cut or cut to make it smooth. , when a polyurethane foam layer is added and foamed. Second
This is a case where a polyurethane foam layer is formed by spray foaming after defective areas such as cracks or missing areas are removed by cutting or cutting to repair the polyurethane foam.

Thirdly, after a polyurethane foam heat insulating material having a predetermined shape is bonded to the area to be heat insulated, when forming a polyurethane foam layer on the heat insulating material by spray foaming, the surface of the heat insulating material is usually cut or cut. Because there are
This is the case when spray foaming of the cut surface or the surface of the cut surface is required. If the polyurethane foam is formed directly on the cut or cut surface of the polyurethane foam by spray foaming, it is difficult to obtain good bonding strength at the joint between the cut or cut surface and the polyurethane foam formed on the cut surface. Extremely difficult.

Generally, the bond strength is reduced to 1/2 to 1/4 of the normal tensile strength of polyurethane foams. Therefore, a technique for bonding a cut or cut surface of a polyurethane foam and a polyurethane foam foamed on the surface with good strength has become an important issue in the construction of a polyurethane foam layer. A general method for spray foaming polyurethane foam with good bonding strength on the cut surface of the polyurethane foam or on the cut surface soil is to apply a surface coating treatment on the cut surface or cut surface of the polyurethane foam in advance to make the surface smooth. After that, there is a technique to spray polyurethane foam.

However, the conventional methods have various drawbacks as shown below. First, when applying a surface coating treatment to the cut or cut surface of polyurethane foam in advance, a trowel coating or brush coating method is usually employed, which requires a long time for application and has extremely poor workability.

Second, when applying paint or the like, it takes a long time for the solvent to evaporate, which is unfavorable in terms of work efficiency.

Furthermore, there is a risk that the polyurethane foam may be soaked by solvent after application of paint or the like. Thirdly, if a surface coating treatment is applied to the cut surface of the urethane foam or the cut surface soil in advance, a thin layer with different physical and chemical properties will exist between the polyurethane layers, and when applying this thin layer, it is necessary to Since strict thin layer construction is required that does not cause any disadvantageous phenomena to the mechanical and thermal properties of the heat-insulating structure, quality selection and management of the materials constituting the thin layer, as well as construction management, are required. It becomes extremely complicated.

Therefore, when forming a polyurethane foam layer by spray foaming on the cut or cut surface of the polyurethane foam, it is easy to work on the cut or cut surface of the polyurethane foam, and it is possible to form a polyurethane foam layer on the cut or cut surface of the polyurethane foam. There is a need for a technology to apply a thin layer or polyurethane foam layer that has a high bonding strength, has little difference in physical and chemical properties from the polyurethane foam that makes up the heat-insulating layer, and has a smooth surface, but this technology is extremely difficult. However, no satisfactory technology has been found yet.

In response to the above-mentioned needs, the present invention aims to smoothly and easily spray-foam polyurethane foam having good bonding strength on the cut surface or cut surface of polyurethane foam, which completely eliminates the drawbacks of the conventional method. The present invention was discovered as a result of intensive research by the following persons, and the present invention is a urethane raw material that forms a polyurethane foam to be additionally foamed when forming a polyurethane foam layer on a cut surface or cut surface of a polyurethane foam by spray foaming. Only the blowing agent in the liquid composition, that is, essential raw materials for polyhydroxy compounds and polyisocyanates, and auxiliary agents such as blowing agents, foam stabilizers, flame retardants, and catalysts, is replaced with a mixture of appropriate amounts of multiple types of blowing agents with different boiling points. A urethane raw material liquid having the same composition is sprayed in advance onto the cut or cut surface of the polyurethane foam to form a dense polyurethane foam layer consisting of the urethane raw material liquid having the same composition as the polyurethane foam to be additionally foamed, and then A method of forming an additional layer of polyurethane foam by spray foaming using a urethane raw material solution having the same composition as the urethane foam to be foamed, thereby obtaining a polyurethane foam layer having good bonding strength on the cut surface or cut surface of the polyurethane foam. It is on offer.

The blowing agents used in the spray foaming of ordinary polyurethane foam are methane dichloride difluoride (CC22F2 boiling point -29.8℃), methane trichloride monofluoride (CCl2F2 boiling point -29.8℃),
1 boiling point 23.8℃), trifluorotrichloromethane (CCl2
FCClF2 (boiling point 47.6°C), etc. are common, and usually only a single type of blowing agent is used, and the amount added varies depending on the density of the polyurethane foam, usually ranging from several parts to 100 parts of the polyhydroxy compound. There are dozens of copies.

In the present invention, based on the research results of the present inventors, a plurality of suitable blowing agents with different boiling points are used as a blowing agent when blowing and foaming a urethane raw material liquid that forms a urethane foam on a cut surface or cut surface of a polyurethane foam. By using a mixture of appropriate types and amounts, foaming occurs in multiple stages during foaming, the foaming speed is slowed down, and a dense polyurethane foam is formed on the cut or cut surface. By doing so, the effect of producing good bonding strength is exhibited.

It is preferable to appropriately select the combination and addition ratio of the plurality of blowing agents used in the present invention based on the properties required by the purpose of use of the polyurethane foam, such as the tensile bond strength and density.

In the present invention, when spraying a urethane raw material liquid having a composition containing multiple types of blowing agents with different boiling points onto the cut surface or cut surface of polyurethane foam, the cut surface or cut surface of the polyurethane foam is completely dense polyurethane. It is important that the urethane foam layer is covered with a smooth surface and has no defects such as pinholes, and that the thickness is as uniform as possible.The preferred thickness of the urethane foam layer is 1 to 101.
It is 1.

Next, the present invention will be described in detail with reference to the accompanying drawings illustrating one embodiment of the present invention.

In Figures 1 to 3, after a polyurethane foam layer (number b) is applied on the surrounding wall (number a) of a structure to be heat-insulated, the surface of the urethane foam layer (number d) is noticeably uneven. For example, after cutting or cutting the surface of the urethane foam layer to form a smooth surface (number c), the polyurethane foam layer must be added and spray foamed.

However, if urethane foam is spray foamed directly on the cut surface or cut surface (number c), it is extremely difficult to obtain good bond strength between the cut surface or cut surface and the added polyurethane foam layer.

Therefore, in the urethane raw material solution composition of the polyurethane foam to be additionally foamed, only the foaming agent having a foaming function is replaced with a mixture of appropriate amounts of multiple types of foaming agents with different boiling points. After spraying on the cut or cut surface (number c) of the K tan foam to form a dense polyurethane foam (number e), an additional polyurethane foam layer (number f) is formed to form a cut or cut surface (number c). The bonding strength in number c) was made good.

The features of the present invention are summarized below. The result is as follows.

The first method is to spray a urethane raw material solution containing multiple types of blowing agents with different boiling points onto the cut or cut surface of the polyurethane foam, and when forming a dense polyurethane foam layer, one blow It is possible to form a dense polyurethane foam layer with a thickness of about 10 m1, and it is possible to foam a new polyurethane foam layer on top of the polyurethane foam, usually 15 to 30 minutes after forming the polyurethane foam. Therefore, the work efficiency is extremely good and it is suitable for on-site construction.

Second, since the dense polyurethane foam that is applied to the cut or cut surface of the polyurethane foam and the urethane foam that is additionally foamed are made of the same urethane resin, the bonding strength between both polyurethane foam layers is good, and the physical The physical and chemical properties are almost the same, and there is no disadvantage to the mechanical and thermal properties of a heat-insulating structure made of a polyurethane foam layer.

The present invention will be explained in more detail below using Examples.

Example 1 Polyurethane foam molded by spray foaming of a urethane raw material liquid composed of a polyhydroxy compound, polyisocyanate, monofluorotrichloride methane as a blowing agent, a phosphate flame retardant, and a silicone resin foam stabilizer. On the cutting surface of the layer, only the blowing agent was added to 1 fluoride trichloromethane and 3
After spraying the urethane raw material solution replaced with a mixture of trichloroethane fluoride to form a dense polyurethane foam, the urethane raw material solution containing only methane trichloride monofluoride as a blowing agent is again spray-foamed to form polyurethane. The tensile bonding strength in the polyurethane foam layer (Case 3) formed by forming a foam and the size of the bubbles constituting the foam were determined by adjusting the tensile bond strength in the polyurethane foam layer (Case 1) that does not include the cutting surface and the polyurethane foam layer (Case 3) that does not include the cutting surface.
A urethane foam layer (case 2) was compared with a urethane foam layer (case 2) when a urethane raw material liquid using chlorinated methane as a blowing agent was directly spray-foamed and molded.

The results are shown in Table 2.

Case 1 (Fig. 4) A polyurethane foam structure that does not include a cut surface and is formed from a polyurethane foam formed by spray foaming of a urethane raw material liquid using trichloromethane monofluoride as a blowing agent.

Case 2 (Fig. 5) A polyurethane foam structure made of polyurethane foam formed by directly spraying and foaming a urethane raw material solution containing monofluorotrichloride methane as the only foaming agent onto the cut surface of the polyurethane foam.

Case 3, (Fig. 6) In the case according to the invention, 1 on the cutting surface of polyurethane foam.
After spraying a urethane raw material solution using a mixture of trifluorotrichloride methane and trifluorotrichloride ethane as a blowing agent to form a dense polyurethane foam, use only monofluorotrichloride methane as a blowing agent again. A polyurethane foam structure constructed by molding an additional layer of polyurethane foam from a urethane raw material liquid.

Table 1 shows the composition ratio of the blowing agent in each of the above cases 1, 2, and 3.

As shown in Table 2, in the case of the present invention, the tensile strength in the foaming direction is almost the same as that of a normal cut surface or a continuous polyurethane foam structure without a cut surface, and even on the cut surface, the tensile strength in the foaming direction is In the case of (Case 3), the cell size of the bubbles was not significantly different from that of the continuous foam structure (Case 1) despite using a blowing agent mixture with different foaming speeds as the blowing agent. It can be seen that according to the present invention, the cut surface or cut surface does not become an obstacle to the heat insulation effect.

[Brief explanation of the drawing]

1, 2, and 3 are diagrams showing an embodiment of the method for forming a polyurethane foam layer of the present invention on a cut surface or a cut surface, and FIGS. 4, 5, and 6 are diagrams showing Example 1, respectively. FIG. 2 is a diagram showing Case 1, Case 2, and Case 3. a... Surrounding wall of the container, b... Polyurethane foam layer, c... Cut surface or cut surface, d...
...A significantly uneven surface of the polyurethane foam layer, e...Polyurethane layer formed from a urethane raw material solution containing multiple types of foaming agents, f...Polyurethane subjected to addition foaming Layer, 1... Polyurethane foam layer formed by spray foaming of a urethane raw material solution containing one type of foaming agent, 2... Cut surface or cut surface, 3... A dense polyurethane foam layer formed by spraying a urethane raw material solution containing multiple types of foaming agents.

Claims (1)

[Claims] 1. Urethane raw material liquid composition that forms the polyurethane foam to be additionally foamed when forming the polyurethane foam layer on the cut surface or cut surface of the polyurethane foam by spray foaming, that is, the polyhydroxy compound, the essential raw material of the polyisocyanate, and the blowing agent, Spray a urethane raw material liquid with a composition in which only the foaming agent in the auxiliary agents such as foam stabilizers, flame retardants, catalysts, etc. is replaced with a mixture of multiple types of foaming agents with different boiling points on the cut surface or cutting surface in advance. After forming a dense polyurethane foam layer made of a urethane raw material liquid having the same composition as the polyurethane foam to be additionally foamed, the polyurethane foam is A method for forming a polyurethane foam layer, characterized by forming an additional layer by spray foaming.