JPS63160827A - Laminated structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a laminated structure using a crosslinked olefin resin open cell foam.

(Prior art) At present, laminated structures made by laminating two-dimensionally expanding base materials such as plastic films and olefin resin foams are widely used as insulation materials, packaging materials, cushioning materials, etc. However, most of the foam layers are closed-cell foams, and cannot be used for applications that require water absorption, air permeability, etc. There has also been a known method in which a closed-cell foam is first produced using an olefin resin, and then foamed by heating and expansion to produce a foam having open cells. The foam will "sag" and have no elasticity.
It was difficult to break the bubbles uniformly, the bubble diameter became coarse, and the texture was rough and the texture was poor, resulting in low commercial value.

In order to solve this problem, Japanese Patent Application Laid-Open No. 56-121739,
Japanese Patent Publication No. 54-63172 describes a method in which closed cells are once formed using an olefin resin and then the cells are broken by pressure. The thickness of the resulting foam becomes thin, and even though the cells are made continuous, the cell membranes overlap, resulting in insufficient absorbency and air permeability.The product only has a single plate shape, making it difficult to use. There was a problem in that it caused a moderate amount of trouble.

(Problems to be Solved by the Invention) To sum up, all conventional practical foamed laminated structures are constructed by pasting a pre-foamed olefin resin foam sheet onto a base material surface. Met. In addition, open-cell foams made of olefin resins used in conventional laminated structures tend to sag, lack elasticity, and are difficult to break uniformly, have large cell diameters, or require two processes. At this stage, the thickness of the obtained foam was thin, and even if the cells were continuous, the cell membranes overlapped, resulting in poor absorbency and air permeability.

The present invention has been made to overcome these conventional drawbacks, and is intended to improve compressive properties, water absorption, weather resistance, and feel in a simple, single step, without the need for a separate step for foam breaking. The object of the present invention is to provide a laminated structure having a continuous olefin resin foam layer.

(Means for Solving the Problems) That is, the laminated structure of the present invention includes (A) an olefin resin, (B) a blowing agent, and (C) a foaming agent on at least one surface of a base material.
A laminated structure obtained by disposing a foamable composition blended with an organic peroxide crosslinking agent and foaming the foamable composition by heating, wherein the olefin (A>) in the foamable composition is The resin has a melting point at a temperature equal to that of the blowing agent (B) and the organic peroxide crosslinking agent (C), and
The blowing agent (A) is contained in an amount sufficient to form open cells in the olefin resin (A) at the melting temperature of the olefin resin and maintain the open cells for a predetermined period of time, and the blowing agent (C) The organic peroxide crosslinking agent is characterized in that it is capable of crosslinking the open cells of the olefinic resin (A>) during or while the open cells are maintained after formation.

The above-mentioned foamable composition includes, for example, (a) 100 parts by weight of an olefin resin (b) decomposition is completed at a decomposition onset temperature (ToS) of 120 to 160°C.
Temperature (T,,) is 150-210℃ and TDS
= 1 to 20 parts by weight of a blowing agent that satisfies the melting point of the olefin resin + 20 to 70°C (C) 0.3 to 20 parts by weight of an organic peroxide crosslinking agent having a one-minute loss temperature (T1/2) of 140 to 190°C 5 parts by weight (d) 0.1 to 10 parts by weight of α-olefin modified surfactant and (e) 0.1 to 30 parts by weight of process oil can be used.

The olefinic resin (a) used in the foamed composition is a homopolymer or copolymer containing olefin as a main component, such as high-pressure polyethylene, low-pressure low-density polyethylene, linear low-density polyethylene ( 1,1 DPE)
, ethylene-vinyl ester copolymer, ethylene-alkyl acrylate copolymer, ethylene-propylene copolymer, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, and mixtures thereof. .

In addition, as the blowing agent (b) used in the above composition,
Azobisisobutyronitrile, azodicarbonamide,
Examples include P-toluenesulfonyl hydrazide, dinitron pentamethylenetetramine, 4,4'-oxybisbenzenesulfonyl hydrazide, and among these, azodicarbonamide is particularly suitable.

The appropriate amount of these blowing agents is in the range of 1 to 20 parts by weight per 100 parts by weight of the olefin resin.
The amount to be used is appropriately determined within this range based on the desired expansion ratio and the amount of gas generated by the foaming agent used.

The foaming agent used in the foaming composition has a decomposition start temperature (Tos) of 120 to 160°C and a decomposition completion temperature (TCP) of 150 to 210°C. 120
If the temperature is lower than 160℃, the bubbles will become coarse.
If the temperature is higher, crosslinking tends to occur first, resulting in a closed-cell foam. It is often difficult to satisfy the above decomposition temperature conditions with a single product, so urea-based compounds, zinc oxide,
It is desirable to add 1 to 10 parts by weight of a decomposition accelerator such as a zinc compound or a lead-based compound to increase the decomposition start temperature (Tos) and completion temperature (T, . . . ) of the blowing agent. Furthermore, if necessary, it is also possible to use two or three types in combination, and this is rather preferable. The decomposition start temperature (T, 8) and the decomposition completion temperature (To, ) were measured using a differential thermal balance at a heating rate of 10°C/min. means a point.

These blowing agents or the combination of blowing agents and decomposition accelerators are
The following relationship is adjusted depending on the olefin resin used.

Decomposition start temperature (T, 8) = (melting point of the olefin resin used) + 20 to 70°C If the decomposition start temperature (TDS) is lower than the melting point of the olefin resin used + 20°C, the viscosity of the resin cannot follow the foaming. However, if the melting point of the olefin resin exceeds 70° C., the resin will flow, making it difficult to properly generate bubbles.

The organic peroxide crosslinking agent (C) used in the above foaming composition is 140%
A temperature range of 190°C to 190°C is used. If the 1-minute half-life temperature (T172) is lower than 140°C, crosslinking will occur first and the foam will become closed cells, and if it is higher than 190'C, the degree of crosslinking will be insufficient and the foam will become coarse cells. Although it is possible to prevent coarse bubbles by adding a larger amount of organic peroxide, it is not practical to add such a large amount of organic peroxide.

Examples of the organic peroxide crosslinking agent used in the foaming composition include the following.

The number in parentheses is the 1-minute half-life temperature ('C).

1.1-bis(t-butylperoxy)cyclohexane (154), t-butylperoxymaleic acid (16)
7), t-butyl peroxylaurate (165),
t-Butylperoxy-3,5,5-trimethylhexane [165], cyclohexane peroxide (174)
), t-butyl peroxyallyl carbonate (17
2), t-butylperoxyisopropyl carbonate (158), 2,5-dimethyl-2,5-di(benzoylperoxy)hexane (162), 2,2-bis(t-butylperoxy)octane (159) ), t-
Butyl peroxyacetate (160), 2,2-bis(t-butylperoxy)butane (160,5),
t-Butyl peroxybenzoate (170), n-
Butyl-4,4-bis(t-butylperoxyberate (166), di-t-butylshiba-oxyisophthalate (168), methyl ethyl ketone peroxide (171), dicumyl peroxide (171),
2,5-dimethyl-2,5-di(t-butylperoxy)hexane (179), α,α'-bis(t-butylperoxy-m-isopropyl)benzene (179),
t-butylcumyl peroxide (176), di-t
-Butyl peroxide (186) These organic peroxide crosslinking agents are suitable for olefinic resin 10
It is necessary to mix it in the range of 0.3 to 5 parts by weight with respect to 0 parts by weight. If it exceeds 5 parts by weight, no improvement in crosslinking efficiency can be expected, and if it is less than 0.3 parts by weight, a sufficient degree of crosslinking cannot be obtained.

In addition, the organic peroxide crosslinking agent used in the above foaming composition is
The decomposition completion temperature (T, P) and the 1-minute half-life temperature (T1) of the blowing agent
It is preferable to select a blowing agent such that the difference (TDP Tl/2 ) is close to 0° C., or to select a decomposition accelerator for a blowing agent.

In this way, in the foamable composition, the decomposition start temperature (T9.) of the foaming agent, the decomposition completion temperature (TDP), and the 1-minute half-life temperature (T1/2) of the crosslinking organic peroxide are balanced, Moreover, the bubbles generated by adding a surfactant and process oil are kept fine and broken.

The α-olefin modified surfactant (d) used in the above foaming composition is suitably one modified with an α-olefin having 4 to 16 carbon atoms, such as polyoxyethylene lauryl ether, oxyethylene lauryl ether, Examples include ethylene oxypropylene block copolymer, polyoxyethylene alkylamine, perfluoroalkyl ethylene oxide, and α-olefin modified silicone.

These α-olefin-modified surfactants have good compatibility with olefin resins and can be smoothly kneaded into olefin resins, so that the effect as a foam stabilizer can be stably obtained.

These α-olefin-modified surfactants need to be blended in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the olefin resin. If the amount is less than 0.1 part by weight, the effect will not be sufficiently obtained, and if it exceeds 10 parts by weight, the effect will not increase any further and it will be uneconomical and problems such as bleeding will occur more easily.

Furthermore, the process oil (e) used in the above-mentioned foaming composition includes naphthenic oils used in rubber, adhesives, etc., but especially those with an aniline point of 100°C or less, a viscosity of 150 CSt or less at 40°C, and SP oils. A stable effect can be obtained when a naphthenic oil having a value of 7.5 to 8.5 is used. The blending amount of these process oils needs to be in the range of 0.1 to 30 parts by weight per 100 parts by weight of the olefin resin. The optimum blending amount varies depending on the type of olefin resin used, but if it is less than 0.1 part by weight, sufficient surfactant and plasticizer effects cannot be obtained, and if it exceeds 30% by weight, bleeding will occur.

Furthermore, antioxidants, pigments, ultraviolet stabilizers, inorganic fillers, flame retardants, other additives, or other resins can be blended into the above-mentioned foamable composition, if necessary.

Furthermore, as the base material used in the present invention, plastic films, nonwoven fabrics, paper, metal foils, mesh materials, pile fabrics, etc. can be used alone or in combination.

In the present invention, in order to laminate the base material and the olefin resin foam sheet, the above-described foamable composition is melt-extruded into a sheet form at a temperature lower than the decomposition temperature of the blowing agent, and is in a softened state immediately after molding. The foamable composition sheet may be laminated with a base material in between, or the foamable composition sheet and the base material may be produced in advance and then laminated using a thermocompression laminator.

The base material and the sheet-like foamable composition may be laminated one by one, one foam composition sheet may be laminated with both sides sandwiched between the base materials, or conversely, one foam composition sheet may be laminated with the other foam composition sheet, depending on the purpose. Both sides of the base material are sandwiched between foam composition sheets and laminated.

The laminated structure laminated in this way is heated at a temperature higher than the temperature required to foam and crosslink the foam composition, specifically, between 150 and 250°C, to foam the foam composition sheet. let This heating is preferably carried out rapidly up to the foaming start temperature, and slowly after the foaming start temperature. Any heating method can be used, such as hot air, infrared heaters, and high frequency heating.

In the laminated structure of the present invention, the cell structure is fixed by cooling after foaming. The cooling temperature at this time is preferably 50°C or less. Note that, if necessary, in order to promote crosslinking, after completion of foaming, it is possible to heat and ripen at a temperature and time that does not destroy the cell structure, and then cool it.

The laminated structure of the present invention can be foamed by a one-step heating method and does not require a step of bursting the foam by applying pressure. Therefore, not only a batch-type manufacturing method but also an endless-type manufacturing method is possible. That is, the thin foam sheet is produced by forming the foamable composition of the present invention into a thin film, laminating it with a base material, and passing it through a heating furnace.
Further, a thick sheet can be manufactured by passing pellets spread in a single layer through a heating furnace.

Furthermore, it is also possible to increase productivity by the conventional method of once producing a bulk foam, slicing it, and laminating it.

Of course, if an extruder, kneader 1, or other mixing method is used to obtain these compositions, the temperature must be such that the crosslinking agent and foaming agent do not substantially decompose.

The foam layer of the laminated structure of the present invention obtained in this way is pure white and has excellent breathability, water absorption, and weather resistance, and is softer than the closed cell type, and has an excellent texture and feel, and therefore is suitable for carpets. It is suitable as a cushioning material, a heat insulating material, a sound absorbing material, etc.

(Example) Next, an example will be described.

Example 1 100 parts by weight of ethylene-vinyl acetate copolymer (melting point 90°C) with a melt index of 15.0 and a maximum content of 14% vinyl acetate, 8 parts by weight of azodicarbonamide, dicumyl peroxide (1 minute loss temperature 171°C) ) 1.5 parts by weight, urea 3
parts by weight, 2 parts by weight of zinc oxide, 2 parts by weight of α-olefin modified surfactant (α-olefin modified silicone) and 10 parts by weight of process oil were kneaded for 5 minutes on a mixing roll with a surface temperature of 100°C. The decomposition start temperature (T 03 ) of azodicarbonamide in this crosstalk is 1
40°C, and the decomposition completion temperature (TDP) is 160°C.

Next, this kneaded material was molded into a 1 mm piece using a press molding machine at 100°C.
The foamable composition was molded into a thick sheet. The foamable composition sheet is then laminated to a thickness of 2.5 mm using a known thermocompression laminator. O
The foamable composition sheet was laminated with ynm pile fabric, placed on a Teflon sheet, and heated in a hot air oven at 180° C. for about 4 minutes, resulting in uniform foaming of the foamable composition sheet. This was cooled at room temperature for 10 minutes to obtain a laminated structure having a soft white open-cell foam layer that was soft to the touch. Table 1 shows the properties of the foam in this laminated structure.

(Space below) 1st table Thickness mm 15 Apparent density g/(,j 0.065 Compressive strength (50%) kg/cl 0.42 Tensile strength
kg/cze 2.0 elongation %
250 Compression set (75% compression) % 6 Cell diameter mm 0.25-0.3 Open cell ratio % 98 Peel strength Material Breakage Example 2 The foamed composition sheet molded by the molding machine in Example 1 was heated using a known method. It was laminated with a 2.0 mm thick polyester nonwoven fabric using a pressure bonding laminator, placed on a Teflon sheet, placed in a cooking microwave oven (manufactured by Matsushita Electric Industrial Co., Ltd.) preheated to 180°C, and heated with high frequency for 2 minutes. Foamed uniformly. When this was taken out and left to cool at room temperature, 1q of laminated structures having foam layers having the same characteristics as the laminated structures obtained in Example 1 were obtained.

Example 3 Melt index 20. Density 0.9160/cni'
of low-density polyethylene (melting point 114°C> 100 parts by weight, 8 parts by weight of azodicarbonamide, α, α′-bis(
1-Butylperoxy-m-isopropyl)benzene (
2.0 parts by weight (1 minute reduction temperature 179°C), 3 parts by weight of urea,
2 parts by weight of zinc oxide, α-olefin modified surfactant (α
-Olefin-modified silicone) 2 parts by weight and 5 parts by weight of process oil were kneaded for 5 minutes with a mixing roll at a surface temperature of IIO'C. Note that the decomposition initiation temperature (T, 8) of azodicarbonamide in this kneaded material is 140°C,
The decomposition completion temperature (T, ) is 160°C.

Next, this mixed material was molded in a press molding machine at 115°C to 1°Om.
The foamed composition sheet was made into a sheet having a thickness of m. Both sides of this foamed composition sheet were bonded to a thickness of 0 using a known thermocompression laminator.
．． 01 TllTl aluminum foil was laminated, and this laminated structure was placed on a Teflon sheet and heated in a hot air oven at 180° C., resulting in uniform foaming in 5 minutes. When this was taken out and cooled at room temperature for 10 minutes, a pure white foam layer having open cells was obtained. The characteristics of this laminated 4I structure are shown in Table 2.

Table 2 Thickness mm 15 Apparent density g/cjo, 068 Compressive strength (50%) kg/cf 1.35 Tensile strength
kg/c! 4.0 Elongation % 50 Compression set (75% compression) % 15 Cell diameter mm 0.3-0.4 Open cell ratio % 98 Peel strength Material Fracture Comparative Example 1 Ethylene-vinyl acetate copolymer used in Example 1 100
parts by weight, 8 parts by weight of azodicarbonamide, 1.5 parts by weight of dicumyl paloxide, 2 parts by weight of α-olefin modified surfactant (α-olefin modified silicone), and 10 parts by weight of process oil at a surface temperature of 100°C. Kneaded with a mixing roll.

The decomposition start temperature (T, , ) of azodicarbonamide in this crosstalk is 198°C, and the decomposition completion temperature (T, , ) is 2
The temperature is 14°C. Next, this kneaded product was molded into a foamed composition sheet with a thickness of 1 mm using a press molding machine at 100°C, and this sheet was placed on both sides of a 50AII11 thick kraft paper and laminated using a known thermocompression laminator. . This unfoamed laminate was placed on a Teflon sheet, placed in a hot air oven at 180°C, and heated for 10 minutes, but no foaming was observed. On the other hand, when a similar press sheet was heated in a hot air oven at 230°C, it foamed uniformly, but
It foamed dimensionally and became a closed cell foam.

Comparative Example 2 When the unfoamed laminates obtained in Examples 1 and 2 were heated in a hot air oven at 250°C for 2 minutes to foam them, the foams had large shrinkage during cooling and had coarse bubbles. .

Comparative Example 3 A laminate was produced in the same manner as in Comparative Example 1 using low-density polyethylene (melting point: 114°C) with a melt index of 20 and a density of 0.916 instead of the ethylene-vinyl acetate copolymer of Comparative Example 1, Although it was foamed, the same foam as Comparative Example 1 was obtained.

Comparative Example 4 A laminated structure was manufactured in the same manner as in Comparative Example 1 using the composition of Example 1 except that the α-olefin-modified surfactant and process oil were removed. In general, good foaming was achieved, but the internal cells were coarse, non-uniform, and open cells.

Comparative Example 5 A laminate was prepared in the same manner as in Comparative Example 1 using the composition of Example 1 except that the process oil was removed, and foaming was performed. A white foam layer was formed in about 4 minutes. It was done.

The apparent specific gravity of this foam layer is 0.07 g/ci? The open cell ratio was 93%, which was close to a satisfactory open cell foam. However, as shown in Table 3, compared to the foam of Example 1, it was inferior in feel, open cell ratio, and flexibility. It was inferior.

Table 3 Thickness mm 14 - Apparent density g/CjO, 07 Compressive strength (50
%) k8/cf O,50 tensile strength ks
/cT11'2.1 Elongation % 220 Compression set (75% compression) % 8.5 Open cell rate
% 93 (Effect of the invention) As is clear from the above examples, the laminated structure of the present invention can be manufactured by a single process, that is, by using a separate process for breaking bubbles, and moreover, The foam layer has an extremely fine and uniform foam structure, and is an open cell with excellent compression properties, water absorption, weather resistance, and feel.

[Brief explanation of the drawing]

The drawing shows the decomposition start temperature (T[)S of the blowing agent in the present invention.
), and the differential thermal analysis curve (DTA) shown below to explain the decomposition completion temperature (TDP). Applicant: Sekisui Chemical Co., Ltd.
III 5 ′□・ ″ rhyme

Claims (1)

[Claims] (1) A foamable composition formed by blending (A) an olefin resin with (B) a blowing agent and (C) an organic peroxide crosslinking agent is placed on at least one side of the base material, and heated. A laminate structure obtained by foaming the foamable composition, wherein the olefin resin (A) in the foamable composition is a foaming agent (B) and an organic peroxide crosslinking agent (C). The blowing agent (B) has a melting point at which it can be melted at the decomposition temperature of (A).
The organic peroxide crosslinking agent (C) is contained in an amount sufficient to form open cells in the olefin resin at the melting temperature of the olefin resin and maintain the open cells for a predetermined period of time, and the organic peroxide crosslinking agent (C) is A foamed laminated structure characterized in that (A) the olefin resin can be crosslinked during the formation of open cells or while the open cells are maintained after formation.