JP3010715B2 - Rubber reinforced styrenic resin composition - Google Patents

Description

The present invention relates to a rubber-reinforced styrenic resin composition, and more specifically, is suitably used for producing a heat insulating box using a urethane foam heat insulating material. More specifically, the present invention relates to a rubber-reinforced styrene-based resin composition, and more particularly to a raw material for producing a structural material in contact with a urethane foam insulation material using 1,1-dichloro-1-fluoroethane (hereinafter referred to as “HCFC-141b”) as a foaming agent. The present invention relates to a rubber-reinforced styrenic resin composition suitable as a rubber composition.

[Background Art] Insulating boxes for the purpose of keeping cold, such as refrigerators and ice machines, are generally formed by, for example, forming a coated or coated steel sheet into an outer box shape (a gate type or a reverse gate type). Combined with a synthetic resin inner box molded into a predetermined shape, urethane stock solution which is a raw material of urethane foam insulation is injected between the inner box and the outer box and then foamed, and the outer box is formed by urethane foam insulation. The inner box is joined and integrated. That is, the urethane foam heat insulating material plays a role as a heat insulating material and is used as a strength member as a structure. The outer box and the inner box may be made of the same material or different materials depending on the purpose of use.

By the way, at the time of urethane foaming, the central part of the urethane foam insulation is 60 ° C. due to the heat generated during the urethane curing reaction.
The above high temperature is reached. For this reason, after the urethane curing reaction,
Upon cooling, the urethane foam insulation shrinks, generating shrinkage stress. The shrinkage stress causes distortion in the urethane foam heat insulating material and the inner box. If the strength of the inner box material is insufficient, a whitening phenomenon and cracks occur in the inner box. Therefore, as the inner box material, the moldability is good, the adhesiveness with the urethane foam insulation material is good, and the stress resistance against low-temperature shrinkage is excellent. It is required to be excellent in impact resistance and also in chemical resistance to contamination of stored things, for example, edible oils, seasonings, etc. Conventionally, ABS resin (acrylonitrile-butadiene-
(Styrene terpolymer), styrene resin, vinyl chloride resin, and the like.

On the other hand, as a foaming agent for urethane foam insulation, CFC-11, which is a fluorocarbon (CCl ₃ F: trichlorofluoromethane), is the most commonly used in terms of heat insulation, toxicity, safety, workability, and cost. I have. Then, the CFC-11 is mixed in a liquid state with the urethane raw material, and is vaporized by the reaction heat of the urethane resin at the time of urethane foaming to form fine cells. CFC-11 in this cell diffuses out of the foam cell over time. Therefore, the inner box is affected by CFC-11 not only when urethane material is injected but also after foaming due to diffusion from inside the cell.

Conventionally, when a styrene resin is used as an inner box material, a protection film or a protection coat is required to prevent direct contact with the foamed material due to low resistance to the CFC-11. Further, the vinyl chloride resin is less susceptible to the influence of CFC-11, but has low heat resistance, and is disadvantageous in that it is deformed by heat during the curing reaction of the heat insulating material, has a low impact strength, and is easily cracked. On the other hand, ABS resin is a material having an excellent balance of moldability, impact resistance, solvent resistance, CFC-11 resistance and the like, and is currently most widely used.

By the way, recently, the production and consumption of chlorofluorocarbons have begun to be regulated internationally as a cause of the depletion of the ozone layer in the stratosphere due to the release of chlorofluorocarbons including CFC-11.
Since CFC-11 is contained in this regulated substance, it becomes difficult to use the urethane foam heat insulating material as a foaming agent as described above, and the use of an alternative foaming agent is being studied. CFC
As an alternative foaming agent for -11, HCFC-141b, which is similar to CFC-11 in physical properties (boiling point, latent heat of evaporation, etc.) and is a substance not subject to the regulation of chlorofluorocarbons, has been proposed.

[Problems to be Solved by the Invention] However, HCFC-141b has higher solubility in a polymer material than CFC-11, and swells in a styrene resin or an ABS resin which is a conventional inner box material. Large dissolving ability. For this reason, substitution with these foaming agents leads to a decrease in strength, breakage, and poor appearance of the box. For example, when HCFC-141b is used as the foaming agent of the urethane foam insulation, the attack of the foaming agent is large in the ABS resin, which is conventionally most widely used as the inner box material, and the inner box cracks or whitens. However, there is a problem that the strength of the refrigerator box or the like is insufficient or the appearance is poor. Therefore, measures such as making the inner box material extremely thick or laminating a film exhibiting excellent resistance to HCFC-141b have been taken, but even if the inner box material is made thicker, Over time, it is affected by HCFC-141b, and in the long term, the quality of refrigerator boxes and the like deteriorates, which is not an essential solution. Further, when the wall thickness is increased, the molding time becomes longer, the productivity is reduced, the material weight is increased, and the weight of the heat insulating box increases. In addition, laminating a material having excellent body HCFC-141b property has an effect of preventing an attack from the HCFC-141b with a necessary minimum thickness, but the effect of the HCFC-141b on the cutout portion of the inner box. There is a problem that a protective structure is required to prevent the occurrence of the problem, the production becomes complicated, and it is difficult to recycle the material because it is composed of different materials.

It is also commonly practiced to mix fillers such as glass fibers (hereinafter referred to as "GF") and carbon fibers (hereinafter referred to as "CF") to improve the mechanical properties of the materials. However, each of GF and CF has a large fiber diameter of 5 to 20 μm and a length of 100 μm to several mm, and has a drawback that the surface smoothness and surface design of a molded product are significantly reduced.
In addition, there is a disadvantage that the formability of the material is reduced by the fiber, and the use of a filler such as GF or CF is not preferable.

The present invention solves the above-mentioned conventional problems and can be manufactured using conventional manufacturing equipment, and even when it comes into contact with a urethane foam insulation material using HCFC-141b as a foaming agent, the strength is reduced and breakage is caused. Another object of the present invention is to provide a rubber-reinforced styrene resin composition that can provide a structural material that does not cause poor appearance.

[Means for Solving the Problems] The rubber-reinforced styrene-based resin composition of the present invention is a rubber-reinforced styrene-based resin for producing a structural material which is in contact with a urethane foam heat insulating material having 1,1-dichloro-1-fluoroethane as a foaming agent. A composition, comprising a rubbery polymer dispersed in particles, and a glassy polymer in which a part of the rubbery polymer particles is chemically bonded to the rubbery polymer particles. The content is 23 to 35% by weight.

 Hereinafter, the present invention will be described in detail.

In the rubber-reinforced styrene resin composition of the present invention, the rubbery polymer as the rubber component includes polybutadiene,
Butadiene rubbery polymers such as styrene-butadiene copolymer and acrylonitrile-butadiene copolymer, alkyl acrylate rubbery polymers such as polyacrylate ethyl ester and polyacrylate butyl ester, polyisoprene, polychloroprene Or one or two of ethylene-propylene-diene rubbery copolymer
Species or more.

In the rubber-reinforced styrenic resin composition of the present invention, these rubbery polymers are dispersed in particles, and a part of the glassy polymer is chemically Are combined. Examples of the glassy polymer include one or more monomers such as styrene, p-methylstyrene, α-methylstyrene, acrylonitrile, an alkyl acrylate vinyl monomer, an acrylate vinyl monomer, and N-phenylmaleimide. And those obtained by polymerizing the body. That is, the rubber-reinforced styrenic resin composition of the present invention is a continuous phase of the glassy polymer in which the rubbery polymer is dispersed in the form of particles and a part of which is chemically bonded to the dispersed particles. It is configured.

Such rubber-reinforced styrenic resin composition of the present invention is, for example, typically an ABS resin.In addition, a so-called AAS resin having an acrylic acid alkyl ester-based rubbery polymer as a rubber component, ethylene-propylene -AESR resin having a diene-based rubbery copolymer as a rubber component, and the like. In practice, the glassy polymer is added to an ABS resin or the like, and is adjusted to the rubber component amount of the present invention. .

In the rubber-reinforced styrenic resin composition of the present invention, the rubbery polymer content is in the range of 23 to 35% by weight, more preferably 25 to 30% by weight. When the rubbery polymer content is less than 23% by weight, when the accelerated deterioration test is performed in combination with a urethane foam insulation foamed using a foaming agent such as HCFC-141b, the rubber-reinforced styrene-based Deterioration such as cracks occurs in the box formed of the resin composition, and if it exceeds 35% by weight, the melt viscosity of the resin is too high, so that molding processing becomes difficult, or the box strength is reduced. Causes inconvenience.

The method for producing the rubber-reinforced styrenic resin composition of the present invention is not particularly limited, but generally, as described above, the above-mentioned glassy polymer is further added to a rubber-reinforced styrenic resin such as an ABS resin. After a predetermined rubber component content is obtained, it is easily prepared by adding and mixing various additives such as a stabilizer and a lubricant as needed.

[Action] The solvent resistance of the rubber-reinforced styrenic resin varies greatly depending on the copolymerization ratio of acrylonitrile as a constituent component. Swell. As described above, general rubber-reinforced styrene-based resins are not necessarily preferable in terms of solvent resistance to HCFC-141b, but the present inventors have proposed a rubber-reinforced styrene-based resin containing the rubbery polymer shown in the claims. A sheet was formed using a resin, and a test (heat cycle test) for repeatedly maintaining the sheet at high and low temperature conditions in contact with the urethane foam insulation using HCFC-141b as a foaming agent was performed. The inventors have found that the sheet in contact with the material does not suffer from deterioration such as cracks, and have reached the present invention.

In addition, since the rubber-reinforced styrene-based resin has excellent processability, characteristics such as colorability, impact strength, and cold resistance are not impaired by the rubbery polymer content of the present invention, the rubber-reinforced styrene-based resin of the present invention HCFC-
It is possible to provide a heat-insulating box body which is not deteriorated for use in contact with a urethane foam heat insulating material using 141b as a foaming agent, and is excellent in moldability and appearance and design.

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples.

In addition, the heat cycle property in an Example and a comparative example was evaluated by the following method. First, after kneading a desired rubber-reinforced styrene resin using an extruder or a Banbury mixer, which is a known method, a sheet is formed by an extruder having a coat hanger die, and this is vacuum-formed to a thickness of about 1 mm. A molded product was obtained. After cutting this vacuum formed sheet to an appropriate size, the outer frame is made of metal with an opening of 200 mm × 1
After being fixed to the upper surface of a lunch box-shaped container having a thickness of 00 mm and a depth of 20 mm, a foamed polyurethane material was injected and foamed into a hollow portion of a hollow container having one surface formed of a resin sheet and the other five surfaces formed of metal. . After the foaming operation, cure at 60 ° C for 30 minutes, and then leave it at -10 ° C for 12 hours and then leave it at + 50 ° C for 12 hours. The condition was observed. As the foamed polyurethane raw material, “# 1903-25” foamed polyurethane raw material manufactured by Toyo Tire & Rubber Co., Ltd. was used. Of these raw materials, only CFCs were replaced with HCFC-141b. In addition, the appearance of the extruded sheet is evaluated by evaluating the color tone and surface gloss and the appearance design as a heat insulating box, and the strength of the extruded sheet is evaluated by evaluating the tensile strength, flexural modulus and surface rigidity of the sheet. Judgment was made in consideration of the strength of the heat-insulating box when incorporated in the box and the susceptibility of the surface of the resin inner box to be damaged.

Example 1 In the presence of a polybutadiene emulsified latex, a styrene monomer, an acrylonitrile monomer, a polymerization initiator and a molecular weight regulator were added to carry out emulsion graft polymerization, and a rubber-reinforced styrene resin containing about 50% by weight of polybutadiene: A I got To this resin A, a separately polymerized styrene-acrylonitrile copolymer was mixed so that the rubber component amount in the resin became the ratio shown in Table 1, and further, a stabilizer, a lubricant and the like were added, and kneading was performed by a known method. The mixture was melt-mixed using an extruder to form pellets. Next, a sheet was formed by using the pellets by the method described above, and the above evaluation was performed. The results shown in Table 1 were obtained.

Example 2 Using an emulsion latex of butyl acrylate rubber as a rubber component, emulsion graft polymerization was carried out in the same manner as in Example 1 to obtain a resin B containing about 50% by weight of an acrylate rubber. The results were as shown in Table 1 in the same manner as in Example 1.

Example 3 Emulsion graft polymerization was carried out in the same manner as in Example 1 using an ethylene-propylene-diene copolymer rubber emulsified latex as a rubber component to obtain a resin containing about 50% by weight of the rubber component: C. The operation was performed in the same manner as in Example 1, and the results in Table 1 were obtained.

Comparative Example 1 For comparison, GSM and GS which are conventional ABS resins for extrusion molding are used.
E, EX200, EX201, EX245 (all of which are Ube Sicon)
The evaluation was performed in the same manner as in Example 1 by using pellets, and the results shown in Table 2 were obtained.

From Table 2, it is clear that any of the ABS resins cracks in the heat cycle test using HCFC-141b as a foaming agent and is unsuitable as an inner box material used for a heat insulating box. .

Comparative Examples 2 to 4 Evaluations were performed in the same manner as in Examples 1 to 3 except that the amounts of the rubber components shown in Table 3 were adjusted in Examples 1 to 3, and the results in Table 3 were obtained.

As is clear from the above results, the intended purpose was able to be achieved by using the rubber-reinforced styrene-based resin composition used in Examples of the present invention.

Although a slight whitening phenomenon may be observed in the above embodiment, the whitening phenomenon is sufficiently practical.

[Effects of the Invention] As described above, according to the rubber-reinforced styrenic resin composition of the present invention, a box in contact with a urethane foam insulating material using HCFC-141b as a foaming agent is excellent in strength and appearance design. A heat insulating box can be manufactured. Moreover, the resin box made of the rubber-reinforced styrenic resin composition of the present invention,
Both can be manufactured using conventional manufacturing equipment, which is industrially extremely advantageous.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-126756 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 291/02

Claims (1)

(57) [Claims] 1. A rubber-reinforced styrenic resin composition for producing a structural material, which is in contact with a urethane foam insulating material having 1,1-dichloro-1-fluoroethane as a foaming agent, comprising a rubbery polymer dispersed in particles. A rubber comprising a glassy polymer in which a part thereof is chemically bonded to the rubbery polymer particles, and the content of the rubbery polymer is 23 to 35% by weight. Reinforced styrenic resin composition.