WO2001060908A1

WO2001060908A1 - Incombustible polyolefin resin composition

Info

Publication number: WO2001060908A1
Application number: PCT/KR2001/000231
Authority: WO
Inventors: Sang Woo Lee; Kyoung Sun Yang; Jong Soo Hong
Original assignee: Samsung General Chemicals Co., Ltd.
Priority date: 2000-02-16
Filing date: 2001-02-16
Publication date: 2001-08-23
Also published as: KR100597448B1; AU2001236142A1; KR20010083534A

Abstract

The present invention relates to an incombustible polyolefin resin composition comprising low density polyethylene, aluminum hydroxide, and compatibility agent consisting of linear low density polyethylene copolymer in which ethylene-based unsaturated carboxylic acid, ethylene-based unsaturated carboxylic acid anhydride, or ethylene-based unsaturated carboxylic acid ester monomer is grafted, linear low-density polyethylene, ethylene vinyl acetate, and polystyrene.

Description

INCOMBUSTIBLE POLYOLEFIN RESIN COMPOSITION

Technical Field

The present invention relates to a novel incombustible polyolefin resin composition. More specifically, the present invention relates to an incombustible polyolefin resin composition comprising low-density polyethylene, aluminum hydroxide and a compatibility agent.

Background Art

Polyolefin-based resin has been widely used in various fields due to its lightweight, inexpensiveness as well as excellent physical properties. However, in case of a fire, the polyolefin-based resin in ^'construction materials is likely to burn, which consequently limits its own utility. For solving this problem, studies on method for improving incombustibility of polyolefin-based resin composition, particularly through addition of bro e-based incombustibility agents, have been vigorously performed for many years. However, the conventional brome-based incombustibility agents are currently being replaced with nonhalogen-based inorganic incombustibility agents in order to prevent a loss of lives in a fire due to noxious gases. Although there are known numerous patents concerning this trend, many problems still remain to be addressed.

US Patent No. 3,915,910 discloses a polyolefin resin composition, wherein incombustibility is achieved by adding wood flour, aluminum hydroxide or magnesium hydroxide, and a compatibility agent to polyolefin. Also, Japanese Laid-open Publications 2-182,415, 10- 076,598 and 10-44,323 disclose incombustible resin compositions, whose incombustibility is secured by adding two types of aluminum hydroxide with different particle size and a dispersant to phenol resin.

Further, European Patent No. 899,092 describes an incombustible resin composition comprising phenol or melamine resin and an incombustibility agent such as aluminum hydroxide or magnesium hydroxide.

In addition to the above prior inventions, Japanese Laid-open Publication 55-44,890 teaches an incombustible resin composition which is prepared by adding borax and perlite as incombustibility agents to polyurethane resin.

However, the resin composition of US Patent No. 3,915,910 has .a problem in that it has poor flexibility, which makes it difficult to be applied on any curved region in a sheet for building materials. Similarly, the resin compositions of Japanese Laid-open Publications 2-182,415, 10-76,598 and 10-44323 as well as European Patent No. 899, 092 have disadvantages in that the composition is prepared by binding inorganic materials with thermosetting resins, and therefore productivity is decreased and bending is completely impossible. Japanese Laid-open Publication 55-44,890 is also undesirable in economic consideration, since it requires relatively elaborate facilities such as a spray-gun for mixing polyurethane resin with borax and perlite.

Summary of the Invention

A feature of the present invention is to provide a novel incombustible polyolefin resin composition, which has superior properties such as: (i) it is scarcely flammable,

(ii) it produces no toxic gases in a fire, (iii) it is flexible enough to be easily applied on any curved region in a sheet for building materials, and (iv) it can be continuously produced using a common extruder, and thus, it is more economical than any of the conventional flame- retardant polyolefin resins.

Disclosure of the Invention

According to the present invention, there is provided a novel incombustible polyolefin resin composition comprising (i) 15-25 wt . % of low-density polyethylene, (ii) 65~80 wt . % of aluminum hydroxide, and (iii) 5~10 wt . % of compatibility agent, wherein said compatibility agent comprises ethylenevinylacetate, polystyrene, linear low- density polyethylene, and linear low-density polyethylene graft copolymer produced by grafting 0.25~5.0 parts of ethylene-based unsaturated carboxylic acid, ethylene-based unsaturated carboxylic anhydride or ethylene-based unsaturated carboxylic ester monomer into 100 parts of linear low density polyethylene. In the present invention, the low-density polyethylene with density of 0.89~0.925g/cm³ and melt index of 4~20g/10min is preferred. In the subject resin composition, the low-density polyethylene is preferably present in 15~25% by weight. If the amount is less than 15 wt.%, the resulting composition is difficult to be extruded and has insufficient flexibility." On the contrary, if the amount is more than 25 wt.%, incombustibility of the composition decreases significantly because of the inherent flammability of the low-density polyethylene.

The aluminum hydroxide used in the present invention preferably has a particle size ranging from 1 to lOμm. Preferably, the aluminum hydroxide content of the subject resin composition amounts to 65~80% by weight. If the content is less than 65wt.%, desired incombustibility cannot be accomplished. Conversely, if the content is more than 80 wt.%, extruding as well as continuous processing cannot be conducted with ease any more. On the other hand, the particle size of the aluminum hydroxide may also have influence on final quality of the composition. That is, if the aluminum hydroxide has a particle size below lμm, the load on extruding increases, which consequently results in the decrease of productivity. In contrast, if the aluminum hydroxide has a particle size over lOμm, surface area of the aluminum hydroxide is insufficient to secure desired incombustibility even at the maximum content or 80 wt.%.

The compatibility agent used in the present invention comprises ethylenevinylacetate, polystyrene, linear low- density polyethylene, and linear low-density polyethylene graft copolymer produced by grafting 0.25-5.0 parts of ethylene-based unsaturated carboxylic acid, ethylene-based unsaturated carboxylic anhydride or ethylene-based unsaturated carboxylic ester monomer into 100 parts of linear low-density polyethylene. This compatibility agent content of the subject composition is preferably 5~10% by weight. If the content is less than 5 wt.%, desired flexibility is not obtained, so that it is substantially impossible to bend any building materials made of the resin composition when applied on a rounded region. Alternatively, it is a waste- of the expensive compatibility agent to use more than 10 wt.%, since flexibility of the final composition does not increase any more.

The detailed composition of the compatibility agent used in the present invention is described below.

A preferred example of the compatibility agent comprises: (i) 30~40 wt.% of ethylenevinylacetate containing 10~20 wt.% of vinylacetate, (ii) 5~15 wt.% of polystyrene, (iii) 15~25 wt.% of linear low-density polyethylene, and (iv) 20~30 wt.% of linear low-density polyethylene graft copolymer produced by grafting 0.25~5.0 parts of ethylene-based unsaturated carboxylic acid, ethylene-based unsaturated carboxylic anhydride or ethylene-based unsaturated carboxylic ester monomer into 100 parts of linear low density polyethylene.

With regard to the graft monomer, preferred ethylene- based unsaturated carboxylic acid includes ethacrylic acid, methacrylic acid, acrylic acid, maleic acid, fumaric acid, and itaconic acid; preferred ethylene-based unsaturated carboxylic anhydride includes maleic anhydride, dodecynyl succinic anhydride, and 5-norbornene-2, 3-anhydride; and, preferred ethylene-based unsaturated carboxylic ester includes glycidyl methacrylate, 2-hydroxy ethyl acrylate, 2-hydroxy ethyl methacrylate, monoethyl maleate, diethyl maleate, di-normal-butyl maleate, and any other polar compounds having analogous structure thereto. According to the present invention, the weight ratio of the graft monomer per 100 parts of the linear low- density polyethylene ranges from 0.25~5.0 parts, preferably 0.5~2.5 parts. In addition, small amount of additives such as antioxidant or paraffin wax may be employed. If the amount of the graft monomer is below 0.25 parts, desired compatibility is not guaranteed. If the amount of the graft monomer exceeds 5.0 parts, numerous problems will be caused, including decrease in efficiency of reaction, severe discoloration, remaining of excessive unreacted monomer, etc. As an initiator of the graft reaction wherein the graft monomers as described above are graft polymerized to the linear low-density polyethylene, one or more compounds selected from the group consisting of acyl peroxide, dialkyl peroxide or aralkyl peroxide, peroxyester, hydroperoxide, ketone peroxide and azo compounds can be employed. The initiator (s) is applied preferably after being impregnated in porous polypropylene powder to 5wt.%, in order to improve the degree of dispersion thereof. Non-limiting examples of acyl peroxide include benzoyl peroxide; non-limiting examples of dialkyl peroxide or aralkyl peroxide include di-t-butylperoxide, dicumylperoxide, cumylbutylperoxide, 1, 1-di-t-butylperoxy- 3, 5, 5-trimethyl cyclqhexane, 2, 5-dimethyl-2, 5- dibutylperoxyhexane, and bis (t-butylperoxy isopropyl) bezene; non-limiting examples of peroxyester include t-butylperoxy pivalate, t-butyl di (perphthalate) , dialkyl peroxy monocarbonate, peroxy dicarbonate, t-butyl perbenzoate, 2, 5-dimethylhexyl-2, 5-di (perbenzoate) , and t- butylperoctate; non-limiting examples of hydroperoxide include t-butylhydroperoxide, p-methane hydroperoxide, and cumene hydroperoxide; non-limiting examples of ketone peroxide include cyclohexanone peroxide, and methyl ethylketone peroxide; and, non-limiting examples of azo compound include azo-bis-isobutyronitrile . 0. 001-1.0, preferably 0.005-0.5 parts of the initiator is added to 100 parts of the basic resin of linear low-density polyethylene. If the amount of the initiator is less than 0.001 parts, homogeneous dispersion of the monomer into the resin fails, so that the graft reaction cannot be successfully accomplished. If the amount of the initiator is more than 1.0 part, the basic resin is bridged simultaneously with the graft reaction, so that the melting fluidity of the resulting composition goes worse, and gelation progresses extremely.

To the resin composition of the present invention may be added further additives such as antioxidant or zinc- stearate (Zn-St) . In particular, the zinc-stearate is used to improve the dispersibilities of both polyolefin resin and aluminum hydroxide .

The incombustible polyolefin resin composition of the present invention can be prepared by the method described below.

The low-density polyethylene and the compatibility agent are applied to a Banbury mixer, and then melted at 130°C. Aluminum hydroxide is added thereto over 2 times, and repetitive mixing is carried out at 160~190°C. Incombustible polyolefin resin composition thus obtained is applied to a single-shaft or double-shaft extruder to provide a final composition in the form of pellet.

The incombustible polyolefin resin composition of the present invention can be used to produce center materials for aluminum complex panels, sheets for wallboard, and complex panels for building materials, for example, according to T-die extrusion method.

Concerning these uses, representative structures can be exemplified by metal/adhesive layer/ incombustible polyolefin resin, aluminum/adhesive layer/ incombustible polyolefin resin/adhesive layer/aluminum, glass/adhesive layer/ incombustible polyolefin resin, aluminum/adhesive layer/incombustible polyolefin resin/adhesive layer/ metal, and the like.

Best Mode for Carrying Out the Invention The present invention can be more clearly understood with referring to the following examples. It should be understood that the following examples are not intended to restrict the scope of the present invention in any manner.

Examples 1~3

Low-density polyethylene (density of 0.920g/cm³, melt index of 10. Og/lOmin) , aluminum hydroxide (particle size of 3μm, Sumitomo C-303) , and a compatibility agent that consists of 30 wt.% of linear low-density polyethylene copolymer grafted with 1. 2 parts of maleic anhydride, 20 wt.% of linear low-density polyethylene, 40 wt.% of ethylenevinylacetate containing 15 wt.% of vinylacetate, and 10 wt.% of polystyrene was melted and mixed in a Banbury mixer in the ratio as presented in Table 1. Then, the mixture was extruded and shaped into pellets at 160~190°C with the use of a single-shaft extruder (50mmψ) . The resin composition thus prepared was processed into .a 3mm thick sheet, and the resulting sheet was heat-adhered to a 0.5mm thick aluminum plate via an adhesive film to provide a test piece, i.e., 4mm thick aluminum complex panel. According to the protocol of KS F2271, surface test, addition test, and test for toxicity of combustion gas were performed using the test piece. Further, bending limit of the test piece was measured by means of a press brake so as to evaluate its flexibility. The results are set forth in Table 1.

[Surface Test] • Standard: KS F2271

• Protocol: The test piece (220mm x 220mm) was heated with a minor heat source for 3min, and further continuously heated with both a minor heat source and a major heat source for 7min. Then,* melting, crack, deformation, remaining of flame, temperature-time-area, and coefficient of emitting smoke per unit area were determined.

• Criterions for judging: no melting, no crack, no deformation time of flame's remaining: < 30 seconds - no temperature increase over standard temperature curve within 3 minutes from the beginning temperature-time-area: < 100 coefficient of emitting smoke: < 60

[Addition Test]

• Standard: KS F2271

• Protocol : A test piece through which three holes (25mm in diameter) had been made was heated according to the same manner as in the above surface test. • Criterions for judging: temperature-time-area: < 150 coefficient of emitting smoke: < 60 time of flame's remaining: < 90 seconds

[Test for Toxicity of Combustion Gas]

• Standard: KS F2271 • Protocol: The mean time was measured, which has been lapsed until each of the eight 5-years-old female rats placed in the gas emitted from combustion of the test piece was not moving any more. • Criterions- for judging: the mean time: > 9minutes

[Test for Flexibility]

• Protocol: The test piece was mechanically bended with a press brake as circularly as possible, and the radius of the resulting circle was defined as its bending limit.

• Criterions for judging: the smaller radius, the better flexibility

Comparative examples 1~4

The procedure of Comparative example was conducted according to the same manner as in the above Example, except that a common compatibility agent, either linear low-density polyethylene copolymer grafted with maleic anhydride or high-density polyethylene copolymer grafted with maleic anhydride was used. The physical properties of the resulting composition are also summarized in Table 1.

Table 1

: linear low-density polyethylene ^**: high-density polyethylene

As can be seen from the above Table 1, compatibility agent of the present invention permits the final resin composition to maintain excellent flexibility even though plenty of aluminum hydroxide has been added thereto. This allows the subject resin composition even better bending property than the conventional compatibility agent does. In addition, the resin composition of the present invention exhibits desirably steady results in the tests for incombustibility such as surface test and addition test and the test for toxicity of combustion gas.

Industrial Applicability

The present invention is to provide a novel incombustible polyolefin resin composition. According to the present invention, a polyolefin resin composition whose physical properties, including incombustibility, flexibility and toxicity of its combustion gas, have been significantly improved can be readily available.

Claims

1. An incombustible polyolefin resin composition comprising (i) 15-25 wt.% of low-density polyethylene, (ii) 65~80 wt.% of aluminum hydroxide, and (iii) 5-10 wt.% of compatibility agent, wherein said compatibility agent comprises ethylenevinylacetate, polystyrene, linear low-density polyethylene, and linear low-density polyethylene graft copolymer produced by grafting 0.25-5.0 parts of ethylene-based unsaturated carboxylic acid, ethylene-based unsaturated carboxylic anhydride or ethylene-based unsaturated carboxylic ester monomer into 100 parts of linear low density polyethylene.

2. The incombustible polyolefin resin ^' composition according to claim 1, wherein the low density polyethylene has a density ranging from 0.89 to 0.925g/cm³ and a melt index ranging from 4 to 20g/10min.

3. The incombustible polyolefin resin composition according to claim 1, wherein the aluminum hydroxide has a particle size ranging from 1 to lOμm.

4. The incombustible polyolefin resin composition according to claim 1, wherein the compatibility agent comprising (i) 30-40 wt.% of ethylenevinylacetate containing 10-20 wt.% of vinylacetate, (ii) 5-15 wt.% of polystyrene, (iii) 15-25 wt.% of linear low-density polyethylene, and (iv) 20-30 wt.% of linear low- density polyethylene graft copolymer.