JPH0749501B2 - Crosslinkable and crosslinkable foamable resin composition for extrusion molding - Google Patents

Description

TECHNICAL FIELD The present invention relates to a crosslinkable and crosslinkable foamable resin composition for extrusion molding, and more specifically to a crosslinkable and crosslinkable resin composition for extrusion molding containing an ionomer resin as a main component. It relates to a crosslinkable foamable resin composition.

(Prior Art) and (Problems to be Solved by the Invention) Crosslinked products of ethylene-based ionomer resins, especially crosslinked foams, have high hardness, high mechanical strength, excellent resilience, and high energy absorption efficiency. In the fields of building materials, footwear, buoyancy materials, automobile parts, sundries, etc., their application development is expected.

However, in order to industrially produce a crosslinked foam of an ionomer resin, there are major obstacles to be solved in terms of its production. The ionomer resin cross-linked foam is generally an ionomer resin and a cross-linking agent, and if necessary, the first step of uniformly kneading the foaming agent at a temperature condition equal to or lower than the decomposition temperature of the cross-linking agent and the foaming agent, and the pellets uniformly kneaded. Alternatively, it is manufactured by a second step of heating a molded article such as a sheet to crosslink and foam. Conventionally, a kneading machine such as a mixing roll, a calender roll, a Banbury mixer or a kneader has been used to uniformly knead the thermoplastic resin, the synthetic rubber and the like with the crosslinking agent and the foaming agent. However, since the ionomer resin has good adhesiveness to metal, when the above-mentioned general-purpose kneader is used, there is a problem that the ionomer resin sticks to the roll and the sheet cannot be continuously molded. In addition, when trying to produce a sheet with an extruder equipped with a T-die, due to the high melt viscosity that is a characteristic of ionomer resin, when the production is performed at an extrusion speed commensurate with the diameter of the extruder used,
Even if the cylinder is water-cooled by heat generation due to shearing in the extruder, the resin temperature rises, and there arises a problem that the crosslinking agent and the foaming agent are decomposed in the first step. Once the cross-linking agent is decomposed in the extruder and the cross-linking is started by the chemical cross-linking agent of the ionomer resin, the viscosity is further increased, the shear heat is further increased, the resin temperature is rapidly raised, the cross-linking agent is decomposed, and the ionomer resin is decomposed. Promotes cross-linking. As a result, the load on the motor increases, and eventually extrusion molding becomes difficult. If extrusion molding is forcibly performed, the appearance of the sheet will be remarkably poor, and thus, even if crosslinking (foaming) is performed in the second step using the molded product as a raw material, a satisfactory crosslinked (foamed) body cannot be obtained.

Therefore, at the current technical level, in order to extrude pellets and sheets of an ionomer resin composition that uniformly contains a cross-linking agent using an extruder, it is possible to produce at a very low production rate ignoring economy, Moreover, the extruder is limited to a special extruder equipped with a cylinder cooling water facility.

Thus, developing a method for uniformly melting and mixing an ionomer resin and a cross-linking agent and, if necessary, a shearing heat of a composition comprising a foaming agent, to uniformly mix and mix in an extruder is to commercialize the ionomer resin cross-linked foam. It is an important issue that must be solved in order to do so.

(Means for Solving Problems) The present inventor has made diligent efforts to solve this problem, and enables stable extrusion molding without impairing the excellent physical properties of the ionomer resin as a crosslinked foam. The present invention has been completed as a result of intensive research conducted for a crosslinkable and crosslinkable foamable resin composition.

According to the present invention, A. 100 parts by weight of a partial metal salt of an ethylene-unsaturated carboxylic acid copolymer or a partial metal salt of an ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer, B. containing vinyl acetate 1 to 15 parts by weight of 3 to 50% by weight of ethylene-vinyl acetate copolymer having a melt flow rate (MFR) of 150 to 1,000 g / 10 min at 190 ° C. and a load of 2160 g, and C. a chemical crosslinking agent AB 0.1 to 5 per 100 parts by weight of total amount of ingredients
There is provided a crosslinkable resin composition for extrusion molding, which comprises:

According to the invention, 100 parts by weight of A. partial metal salt of ethylene-unsaturated carboxylic acid copolymer or partial metal salt of ethene-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer, B. vinyl acetate 1 to 15 parts by weight of ethylene-vinyl acetate copolymer having a content of 3 to 50% by weight and a melt flow rate (MFR) of 150 to 1,000 g / 10 min at 190 ° C. and a load of 2160 g, C. Chemical Crosslinking Agent A 0.1 to 5 per 100 parts by weight of B component total amount standard
Parts by weight, and D. chemical blowing agent 0.1 to 20 per 100 parts by weight based on the total amount of components A and B
There is provided a cross-linkable foamable resin composition for extrusion molding, which comprises:

The partial metal salt of the ethylene-α, β unsaturated carboxylic acid copolymer used as the component A of the present invention is, for example, JP-B-39.
It is manufactured by the method described in JP-6810. That is, a copolymer of ethylene and an unsaturated carboxylic acid having 3 to 8 carbon atoms such as acrylic acid, methacrylic acid, ethacrylic acid, itaconic acid, and fumaric acid, or a copolymer of methyl acrylate, ethyl acrylate, and isobutyl acrylate. ,
C4-8 such as normal butyl acrylate, methyl methacrylate, ethyl methacrylate, normal butyl methacrylate, isobutyl methacrylate, dimethyl fumarate
Is a metal ion-crosslinked part or all of the carboxylic acid groups in the terpolymer containing the α, β-unsaturated carboxylic acid ester as the third component. The content of unsaturated carboxylic acid in the copolymer is generally about 0.5 to 15 mol%, preferably about 1 to 6 mol%. The content of unsaturated carboxylic acid ester copolymerized as the third component is generally about 0.2 to 15 mol%, preferably about 1 to 10 mol%.

Examples of the metal ion used for metal ion crosslinking include monovalent metal ions such as lithium, sodium, potassium and cesium, magnesium, calcium, strontium,
Examples thereof include divalent metal ions such as barium, copper and zinc or trivalent metal ions such as aluminum and iron. The metal ion used in the form of the metal compound may vary depending on the content of the acid in the copolymer, the melt flow rate at 190 ° C and a load of 2160g (hereinafter referred to as MFR, a unit g / 10min), the type of the ion and its application. Although the amount added varies, it is generally used in an amount of neutralizing about 10% or more, preferably about 15 to 80% of carboxylic acid groups.

The MFR of the copolymer and its metal salt is preferably about 0.1 to 500, preferably about 1 to 100. Below this, the moldability becomes poor, and above this, the strength of the molded product is insufficient. Like

It is possible to select one of these metal salts to use, but adjust the unsaturated carboxylic acid (ester) content, metal type, neutralization degree, MFR, etc. to achieve the desired physical properties. In order to obtain the crosslinked product, it is possible to use a partial metal salt of two or more copolymers or a blend of a partial metal salt and a copolymer.

The ethylene-vinyl acetate copolymer used as the component B of the present invention generally comprises ethylene and vinyl acetate as a polymerization initiator of oxygen or various organic peroxides, azo compounds, acetoximes, aminic acid compounds, etc. 1000-3000
It is produced by radical bulk polymerization carried out under high pressure at atmospheric pressure. The vinyl acetate content in the copolymer is about 3 to 50% by weight, preferably 10 to 50% by weight. When a copolymer having a vinyl acetate content of 3% or less is used, compatibility with the component (A) is lost, and crosslinking efficiency, flexibility and elasticity are reduced, which is not preferable. On the contrary, when 50% or more of the copolymer is used, the foam becomes too soft and the strength of the waist is lost, which is not preferable.

It is desirable that the MFR of the B component is in the range of 150 to 1,000, preferably 150 to 500. The use of a copolymer having an MFR lower than this value is not preferable because the effect of lowering the melt viscosity is small, the rise in resin temperature due to heat generation by shearing cannot be prevented, and the object of the present invention cannot be achieved. On the other hand, when a copolymer having a high MFR is used, the melt tension is small and the work in the granulation and cross-linking steps becomes complicated, which is not preferable.

The mixing ratio of component A to component B is 100 parts by weight of component A to B.
1 to 15 parts by weight of the component. If the amount is less than 1 part by weight, the desired effect of lowering the melt viscosity cannot be obtained. On the other hand, if it exceeds 15 parts by weight, the cross-linked molded article loses its properties from the original ionomer resin, which is not preferable. As the chemical cross-linking agent used as the component C of the present invention, a radical is generated by heating,
Conventional organic peroxide crosslinking agents that cause a crosslinking reaction in the polymer can be used. As a preferable crosslinking agent,
For example, dicumyl peroxide, 2,5-dimethyl-2,5-
Bis tert-butyl peroxyhexane, 2,5-dimethyl-
A general formula ROOR such as 2,5-ditertiary butylperoxyhexyne-3 or 1,3-bis (tertiary butylperoxyisopropyl) benzene (wherein R is an alkyl group, an aryl group and other substituents) Can be substituted). Generally, it is used in a ratio of about 0.1 to 5 parts by weight based on 100 parts by weight of the total amount of A and B components.

It is also possible to appropriately select and use two or more kinds of the crosslinking agents having different decomposition temperatures in combination.

A foaming agent may be added to the crosslinkable resin composition of the present invention.

As the foaming agent, any decomposing type that generates a gas necessary for foaming the resin by heating, that is, any chemical foaming agent can be used, for example, azodicarbamide, dinitrosopentamethylene. Tetramine or the like, alone or as a mixture, generally about 0.1 to 20 parts by weight, preferably 0.5 to about 100 parts by weight of the total amount of components A and B, based on the standard.
Used in a proportion of up to 10 parts by weight.

Further, the crosslinkable and crosslinkable foamable resin composition of the present invention, a rubber-like elastic polymer such as ethylene-α-olefin copolymer, styrene-butadiene rubber, polybutadiene rubber, A, B component total amount 100 parts by weight It is also possible to mix at a ratio of about 30 parts by weight or less.

Furthermore, the crosslinkable and crosslinkable foamable resin composition of the present invention can be blended with various other additives commonly used in this technical field, if necessary. Examples of such other additives include crosslinking accelerators, foaming aids, antioxidants, light stabilizers, ultraviolet absorbers, antistatic agents, lubricant antiblocking agents, organic or inorganic pigments, dyes and the like. be able to.

In order to uniformly mix the above essential components A, B, and C and optional components, they may be melt-mixed simultaneously or sequentially with a single-screw extruder, a twin-screw extruder or the like.

The crosslinkable and crosslinkable foamable resin composition of the present invention is, for example, T
-Form into a sheet with a die, roll or the like, and carry out cross-linking or cross-linking and foaming using a press, a furnace, a foaming bath or the like. The temperature condition of the press or the like varies depending on the type of the chemical crosslinking agent, the foaming agent, the foaming auxiliary agent, etc., but is generally set to about 150 to 250 ° C.

The cross-linked product obtained from the cross-linkable resin composition of the present invention is a heat-resistant sheet, or the cross-linked foam is a heat insulating material, sound absorbing material, wall material, packing, shoe sole, float for fishing industry, automobile parts, miscellaneous goods, etc. used. Of course, known secondary processing techniques such as slicing and punching can be freely applied.

(Working) Ionomer resins have been conventionally used for various molded product applications such as films and extrusion coating by extrusion molding. However, extrusion molding an ionomer resin composition containing a cross-linking agent, a foaming agent, etc. that decomposes at a relatively low temperature with an extruder has a high melt viscosity of the ionomer resin, and shear heat generation is an obstacle to the normal extrusion rate. It was difficult under the conditions. Further, since the ionomer resin has good adhesion to metal and strong roll adhesiveness, it was not possible to use a general-purpose kneader such as a mixing roll or a Banbury mixer which is widely used for kneading rubber or thermoplastic resin. .

The present inventors blended 1 to 15 parts by weight of an ethylene-vinyl acetate copolymer with 100 parts by weight of an ionomer resin containing a cross-linking agent and a foaming agent, without impairing the quality of a molded product, and using an extruder. The present invention has been completed by finding that it is possible to largely prevent the heat generation by shearing inside.

By the completion of the present invention, it has become possible to continuously and economically produce a crosslinkable resin composition and a crosslinkable foamable resin composition containing an ionomer resin as a main component, which has been difficult in the past, industrially and economically. This is remarkable.

(Example) Sample: Table 1 shows the composition and MFR of the polymer used in the example.

Examples 1 to 9 Comparative Examples 1 to 4 The polymers shown in Table 2 were dry blended at a predetermined ratio, and a 30 mm extruder (L / D) equipped with a profile extrusion die capable of molding a 10 × 10 mm square bar at the tip (L / D = 22, metering screw). The rotation speed of the extruder was 50 rpm, the temperature of each point in the extruder (cylinders 1, 2, 3, die) was set to 110 ° C, and the motor load and the resin temperature in a stable state were measured. In addition, in the experiment of Table 2, the purpose was to clarify the relationship between the blending ratio of the supplied polymer and the rise in the resin temperature due to heat generation by shearing. Therefore, the addition of the chemical crosslinking agent and the passage of the cylinder cooling water were not performed. .

In Table 2, comparing Experiments 1 and 2 with Comparative Examples 1 and 2, it can be seen that even with the same MFR, the increase in the resin temperature is small in the case of the example.

Comparative Examples 3 and 4 show that addition of LDPE, EPR, etc. is not effective in preventing the resin temperature from rising.

Examples 3 to 5 show the effects when the amount of EVA added is changed within the range of 2.5 to 15%.

Examples 6-8 show the effect of using EVAs with different vinyl acetate contents.

As can be seen from the above experimental results, when extrusion molding is carried out using the composition of the present invention, the rise in the resin temperature due to heat generation due to shearing is not so large. When the composition in which the resin temperature does not rise so much is used, the chemical crosslinking does not occur in the extruder in the first step when the chemical crosslinking agent is contained, and the composition is preferable when the crosslinking is performed in the second step. It is possible to produce pellets and sheets from which molded articles can be obtained in the first step.

Examples 9 and 10 Ionomer resin A (Example 9) or B (Example 10)
100 parts, EVAb 5 parts, chemical cross-linking agent 2,5-dimethyl-2,5-di (tertiary peroxy) -hexyne-3 1.3 parts,
Similarly, 0.43 parts of 1,3-bis- (tert-butylperoxy-isopropyl) -benzene, a chemical cross-linking agent, 3 to 5 parts of a foaming agent azodicarbonamide and 3 to 5 parts of a foaming aid zinc stearate are dry-blended to obtain a tip. The sheet was fed to a 30 mm extruder equipped with a T-die, and a sheet having a thickness of about 0.7 to 1.0 mm was formed. The conditions at the time of forming the sheet were such that the extruder rotation speed was 50 rpm and the temperature at each point of the extruder was set to 110 ° C. At this time, water is passed through the cylinder cooling jacket to cool the resin to 12
Keep at 0 ° C or below.

Next, several sheets were placed in a mold of 200 × 200 × 11.5 mm so that a predetermined amount (460 g) of the basis weight was overlapped and heated at 170 ° C. for 20 minutes. The mold was opened, and the density, hardness, tensile strength, and tear strength of the resulting foams having various expansion ratios were measured. The results are shown by the density of the foam on the horizontal axis and the hardness (FIG. 1), tensile strength (FIG. 2), and tear strength (FIG. 3) on the vertical axis.

Comparative Examples 5 and 6 In Examples 9 and 10, 5 parts of EVAb were replaced with ionomer resin A (Comparative Example 5) or B (Comparative Example 6), respectively, and an extruder was used for the purpose of preventing decomposition of the crosslinking agent and the foaming agent in the extruder. The procedure was performed in the same manner as in Examples 10 and 11 except that the rotation speed was reduced to 30 rotations / minute and the amount of cylinder cooling water was increased to strengthen the cooling.

The measurement results of the properties of the obtained foams are shown in FIGS. 1 to 3 and compared with Examples 9 and 10.

In the comparison between Examples 9 and 10 and Comparative Examples 5 and 6, in Examples 9 and 10, the effect of significantly reducing the extrusion torque and suppressing the resin temperature rise was obtained as compared with Comparative Examples 5 and 6. It was found that the physical properties of the crosslinked foam had almost no change despite the incorporation of 5 parts EVA.

[Brief description of drawings]

1 to 3 are graphs showing the relationship between the expansion ratio and the physical properties of the crosslinked foams obtained from the resin compositions of the present invention (Examples) and Comparative Examples. Fig. 1 shows the foam density and A _{SKER C} -hardness. Fig. 2 shows the foam density and tensile strength, and Fig. 3 shows the relationship between the foam density and the degree of tear.

Claims (2)

[Claims] 1. A. Partial metal salt of ethylene-unsaturated carboxylic acid copolymer or 100 parts by weight of partial metal salt of ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer, B. Vinyl acetate content 3 to 50% by weight of ethylene-vinyl acetate copolymer having a melt flow rate (MFR) of 150 to 1,000 g / 10 min at 190 ° C. and a load of 2160 g, 1 to 15 parts by weight, and C. chemical crosslinking agent AB component A crosslinkable resin composition for extrusion molding, which comprises 0.1 to 5 parts by weight per 100 parts by weight based on the total amount. 2. 100 parts by weight of A. partial metal salt of ethylene-unsaturated carboxylic acid copolymer or partial metal salt of ethene-unsaturated carboxylic acid-unsaturated carboxylic acid ester copolymer, B. vinyl acetate content 1 to 15 parts by weight of 3 to 50% by weight of ethylene-vinyl acetate copolymer having a melt flow rate (MFR) of 150 to 1,000 g / 10 min at 190 ° C. and a load of 2160 g, C. Chemical cross-linking agents A and B 0.1 to 5 per 100 parts by weight of total amount of ingredients
Parts by weight, and D. chemical blowing agent 0.1 to 20 per 100 parts by weight based on the total amount of components A and B
A cross-linkable foamable resin composition for extrusion molding, which comprises: