JPS63152649A - Coated polyolefin foam - Google Patents

Abstract

PURPOSE:To obtain the titled coated product having improved weather- resistance, surface appearance, stain resistance, surface strength, etc., without deteriorating the characteristics of the base resin, by coating an olefin foam with a coating composition containing a specific acrylic copolymer and a polyisocyanate compound. CONSTITUTION:A polyolefin foam is coated with a composition produced by compounding (A) an acrylic copolymer having a glass transition temperature of -20-+5 deg.C and a number-average molecular weight of 3,000-30,000 (deter mined by gel-permeation chromatography) and containing 5-30wt.% copolymerized acrylic monomer having hydroxyl group with (B) a polyisocyanate compound or compounding (C) a composition composed of (C1) 95-40wt.% acrylic copolymer having a glass transition temperature of -10-+30 deg.C and a number-average molecular weight of 3,000-30,000 and containing 5-30wt.% copolymerized acrylic monomer having hydroxyl group and (C2) 5-60wt.% compound having >=2 hydroxyl groups with (D) a polyisocyanate compound.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a polyolefin foam coated with an acrylic copolymer or a coating composition containing the copolymer as a main component.

<Conventional technology> Conventional polyolefin foams have excellent cushioning properties, flexibility,
Due to its heat insulating and buoyant properties, it is used in a variety of applications, such as packaging and packaging materials, automobile interior materials, heat and cold insulation materials, buoyancy enhancing materials, etc.

-Polyolefin foams in particular have very poor weather resistance, deteriorate significantly due to ultraviolet rays, that is, deteriorate appearance and mechanical properties, and cannot withstand long-term use, so their use outdoors has been restricted.

In order to solve these drawbacks, felt or asbestos has been composited onto the surface of the foam, or various films or sheets made of polyethylene, polypropylene or polyvinyl chloride have been fused or adhered. However, these effects are not only insufficient, but also accompanying problems such as deterioration of the excellent properties of the foam and increased manufacturing and processing costs have not been solved.

A method of painting plastic foam with paint has also been proposed in Japanese Patent Application Laid-open No. 40542/1983.

However, in the case of polyolefin foams which have particularly poor weather resistance, it is not possible to obtain weather resistance sufficient to withstand outdoor use by the usual method of laminating paint. The surface of the foam is exposed and deteriorates due to cracking due to deterioration of the paint itself or peeling due to decreased adhesion. In other words, it is known that polyolefin foams inherently have low surface energy and have extremely low adhesive strength with ordinary paints.
Even if the paint itself has excellent weather resistance, problems can occur such as peeling due to poor adhesion and cracking during bending due to poor adhesion or poor mechanical properties. Therefore, especially in the case of polyolefin foam, it goes without saying that the paint itself has excellent weather resistance, but also that the adhesion between the paint and the polyolefin foam is excellent and that the mechanical properties of the paint are excellent. The weather resistance of polyolefin foams can be significantly improved unless they also meet the requirements of preventing cracking of the paint film due to bending of the foam (in this respect, the adhesion of the paint is also relevant). It is not possible.

<Problems to be Solved by the Invention> Therefore, the present inventors have developed a method that provides excellent weather resistance, excellent adhesion to polyolefin foam, and excellent adhesion to polyolefin foam without reducing the properties of the polyolefin foam. The present invention has been completed through extensive research aimed at improving the mechanical properties as well as cosmetic properties, stain resistance, and especially the surface strength of highly foamed products.

Means to solve problems〉 That is, the present invention has the following configuration.

(1) Acrylic material copolymerized with 5 to 30% by weight of a hydroxyl group-containing acrylic monomer, with a glass transition temperature of 120 to 5°C and a number average molecular weight of 3,000 to 30,000 as measured by gel permeation chromatography. A polyolefin foam coated with a coating composition containing a polyisocyanate compound and a polyisocyanate compound.

(2) A, copolymerized with 5 to 30% by weight of hydroxyl group-containing acrylic monomer at a glass transition temperature of -10 to 30°C and a number average molecular weight of 3000 to 3000 as measured by gel permeation chromatography. 30,000 acrylic copolymer (
If>95 to 40% by weight, B, a composition in which 5 to 60% by weight of a compound ([1) having two or more hydroxyl groups is mixed or copolymerized, and C, a polyisocyanate compound. Polyolefin foam coated with material.

The acrylic copolymer (I> is a copolymer of 55 to 30% by weight of a hydroxyl group-containing acrylic monomer [component (A)]. In the present invention, the acrylic copolymer (I> In this component (a), an alkyl or cycloalkyl ester of acrylic acid or methacrylic acid [component (b)]
] and other copolymerizable monomers (component (c)) are preferred. A coating film obtained from an acrylic copolymer copolymerized with these components is a synthetic resin coating film. It is generally known that it has excellent weather resistance.

However, as a coating film for lamination with a polyolefin foam, a coating film obtained from a specific acrylic copolymer must have excellent weather resistance, adhesion to the polyolefin foam, and mechanical properties. be. Acrylic copolymers that give coated polyolefin foams excellent weather resistance, adhesion with polyolefins, and mechanical properties without reducing the properties of polyolefin foams include acrylic copolymers containing hydroxyl group-containing acrylic media. It is determined by the amount of copolymerization, the limited number of other acrylic monomers, the glass transition temperature of the copolymer, and a specific range of number average molecular weight. The details will be explained below.

Component (A) used for producing the acrylic copolymer (I) is a hydroxyalkyl ester of acrylic acid or methacrylic acid, such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate.
Acrylates are preferably used. The amount used is 5 to 30% by weight, preferably 10 to 25% by weight.

When the amount of acrylic monomer containing hydroxyl group is 5 to 30% by weight, the OH value is 21 to 1 when converted to 2-hydroxy methacrylate.
It corresponds to 30. If the usage period is too low, the flexibility of the coating film will improve, but the crosslinking density will decrease, resulting in a decline in not only weather resistance but also physical and scientific properties such as strength, stain resistance, and gasoline resistance of the coating film. If the amount is too high, the weather resistance, physical, and chemical performance will improve, but the crosslinking density will increase, making the coating hard and reducing the flexibility of the polyolefin foam.
In either case, the effect of the present invention becomes weaker. Component (b) is preferably an ester of acrylic acid or methacrylic acid and an aliphatic monohydric alcohol, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-
Butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, lauryl (meth)acrylate
Acrylate and stearyl (meth)acrylate are used.

Ingredients (c) include styrene, vinyl acetate, acrylonitrile, (meth)acrylamide, etc.
Although it is possible to use materials that can be copolymerized with (b), it is not preferable to use acrylonitrile or (meth)acrylamide from the viewpoint of adhesion to the polyolefin foam.

Components (b) and (c) are the relationship between component (a), the generally known glass transition temperature, and the copolymer composition (where Tg is the copolymer, and Tgl and Tg2 are the pure monomers, respectively). The glass transition temperatures of monomers 1 and 2 are expressed as absolute temperatures.W and W2 are the monomer fractions corresponding to monomers 1 and 2). Polymerized.

The glass transition temperature of the acrylic copolymer (I> is -20 to 5
℃, preferably in the range of -15 to O'C. If the glass transition temperature is too low, the flexibility of the coating will improve, but the weather resistance (crack resistance will improve, but the gloss will decrease significantly)
Not only that, but the tackiness of the paint film becomes severe, and performance such as stain resistance and gasoline resistance deteriorates. If it is too high, these properties will be improved, but the coating film will become hard and crack when bent, and the flexibility of the polyolefin foam will be reduced, both of which will reduce the effects of the present invention.

In addition, from the point of view of adhesion to polyolefin foam, n-
It is preferable to copolymerize 30 to 60% by weight of butyl acrylate or 2-ethylhexyl acrylate. If the amount is too large, the tackiness of the coating film will be severe, and if it is too small, the adhesion to the polyolefin foam will be poor, which is not preferable.

The number average molecular weight of the acrylic copolymer (I) measured by gel permeation chromatography is 3000 to 30
000, but a range of 5,000 to 20,000 is particularly preferable.

If the molecular weight is too low, the appearance of the coating will be improved, but the weather resistance will be greatly reduced, as well as flexibility at low temperatures and general physical and chemical performance. On the other hand, if it is too high, not only the weather resistance but also the flexibility at low temperatures will be improved, but the solubility of the resin, the painting workability, and the appearance of the coating film will deteriorate, which is not preferable.

As the method for polymerizing the acrylic copolymers (I> and (II)), solution radical polymerization is preferred.

Acrylic copolymer with a glass transition temperature of -10 to 30°C (
In the case of n), a compound having two or more hydroxyl groups (II
Mix or copolymerize with I). In this case, the compound (I[I) having two or more hydroxyl groups is preferably, for example, a polyester polyol, polyether polyol or polycarbonate diol having a hydroxyl group at the terminal or side chain. These may be used alone or in combination of two or more. In addition, the number average molecular weight of these compounds measured by gel permeation chromatography is 500 to 7.
000. Particularly preferred is a range of 1000 to 5000. If the molecular weight is less than 500, it may give the coating a sticky feel,
Weather resistance and other properties - undesirable because it reduces the physical properties of the film.

If the molecular weight is 7000 or more, acrylic copolymer (n)
This compound (I) is more flexible than the acrylic copolymer (II) and is not suitable for use with polyolefin foams. Although it is a preferred laminating agent for coated objects such as acrylic copolymers, it tends to have inferior weather resistance compared to acrylic copolymers.Acrylic copolymers (II) are therefore used in the coating composition of the present invention. 95 to 40% by weight, B, 2
A composition is prepared by mixing or copolymerizing 5 to 60% by weight of the compound (III) having at least 1 water M group. Each of these may be used alone or in combination of two or more to form a composition, but the compound (III) having two or more hydroxyl groups is 5 to 60% by weight, preferably 20 to 50% by weight in the composition. A range of is appropriate. If it is less than 5% by weight, it is not preferable because sufficient flexibility cannot be obtained and cracks are likely to occur when the foam is coated. Moreover, if it exceeds 60% by weight, weather resistance decreases, which is not preferable.

The glass transition temperature of the acrylic copolymer (n) mixed and copolymerized with the compound (III) having two or more hydroxyl groups is preferably -10 to 30°C in view of the relationship with the compound (III). If it is below -10°C, it is not preferable because the addition of compound (III) may leave the coating film sticky or deteriorate its stain resistance, gasoline resistance, and other properties. At temperatures above 30° C., even if a highly flexible compound (III) is mixed or graft polymerized, the coating film becomes hard and cracks occur when bent, which is not preferable.

The acrylic copolymer (II> and the compound (III) may be simply blended together, or the compound (Ill
)'', the components of the acrylic copolymer (II>) may be graft copolymerized using a peroxide radical catalyst.

A polyisocyanate compound is a compound having two or more isocyanate groups. For example, adduct type or biuret type isocyanates. For example, adducts of toluylene diisocyanate, diphenylmethane diisocyanate, or isophorone diisocyanate with trimethylolpropane, and adducts of hexamethylene diisocyanate with biuret and trimethylolpropane can be used. Preference is given to applying family isocyanates.

In the present invention, acrylic copolymer (I) and polyisocyanate compound, or acrylic copolymer (II)
The blending ratio of the mixture or copolymer of and compound (I[I) and the polyisocyanate compound is NC0ZOH and 0.
．． A molar ratio of 5 to 1.5 is preferred, but not limited thereto.

When formulating the coating composition of the present invention, the acrylic copolymer (I>
and a polyisocyanate compound, or a mixture or copolymer of acrylic copolymer (I) and compound (III) and a polyisocyanate compound.

Although the coating composition of the present invention can be used in the form of a clear coating, it is preferably used by adding one or more of aluminum powder and pigments such as white, red, blue, and black. That is, by improving the hiding power of the paint by adding aluminum powder or various pigments, it is possible to prevent the transmission of ultraviolet rays and prevent the polyolefin foam from deteriorating. Further, if necessary, glass powder, mica, fibers, etc. can be added for the purpose of reinforcing the coating film, and a flame retardant can be added for the purpose of flame retardation to form a paint.

The polyolefin foams referred to in the present invention are particularly effective in semi-rigid polyethylene having a closed cell structure, ethylene-vinyl acetate copolymer resin, and polypropylene foam.

<Examples> Example 1 100 parts of monomers and dodecyl mercaptan having the composition shown in Table 1 were stirred at 84 to 87°C for 7 hours in the presence of a solvent of 34.3 parts of toluene, ethyl acetate B, and 6 parts. Tg-7℃, 08
An acrylic copolymer having a valence of 35 and a number average molecular weight of 8,500 was obtained.

Titanium oxide and xylene/cellosolve acetate at a ratio of 80/201t are mixed into the above copolymer composition according to the pigment paste formulation shown in Table 1, an appropriate amount of glass peas for a sand grinder is added, and the mixture is shaken with a paint conditioner for about 1.5 hours. to obtain a pigment paste.

The above copolymer and polyisocyanate (Sumidur N-75 (manufactured by Sumitomo Bayer Urethane Co., Ltd.)) were blended into the obtained pigment paste according to the coating formulation shown in Table 1, and while stirring, xylene/cellosolve acetate was mixed with 80% A paint was obtained by diluting it with a mixed solvent at a weight ratio of /20 to a viscosity suitable for spray painting.

The paint made in this way is made into polyethylene foam [
"Torepef" 3006 (manufactured by Toshiv/J)] was spray-painted and heated at 70°C for 30 minutes, with a dry coating film of 60 to 70%.
1 q of μ coated foam was obtained.

A. The above coated foam and uncoated foam were irradiated with accelerated weather resistance tester (QtJV tester) at 70°C for 8 hours, with condensation at 50°C.
The test was conducted under 4 hour cycle conditions. As a result, while the unpainted foam developed a full-scale crank in 130 hours,
No cracks were observed in the painted foam even after 1500 hours.

B. The painted foam and unpainted foam described above were subjected to a 22-month outdoor exposure test from September 1975 to July 1977 in Ichihara City, Chiba Prefecture. As a result, as shown in Figure 1, the surface deterioration of the unpainted foam became noticeable after about 8 months.
In the second month, the elongation retention rate decreased to 10%, but the coated foam had a good elongation retention rate of 90% in the 22nd month, although the surface gloss decreased slightly.

Comparative Example 1 100 parts of the monomers shown in Table 1 were polymerized in the same manner as in Example 1, Tq -7°C, 08 valence 35, number average molecular weight 2000.
An acrylic copolymer was obtained.

A paint was then prepared using the pigment paste and paint formulation shown in Table 1, and a painted foam was prepared in the same manner as in Example 1.

The painted foam thus prepared was treated with QU in the same manner as in Example 1.
As a result of accelerated weathering test using V test machine, 500
Over time, the paint film deteriorated significantly and many cranks occurred.

Comparative Example 2 100 parts of the monomers shown in Table 1 were polymerized in the same manner as in Example 1 to obtain a polymer with a Tg of -6°C, an OH value of 13 (hydroxyl group-containing acrylic semisolid type weight % of 3%), and a number average molecular weight of 9000. An acrylic copolymer was obtained.

Then, a paint was prepared using the pigment paste and paint formulation shown in Table 1, and a painted foam was obtained in the same manner as in Example 1.

The painted foam thus prepared was treated with QU in the same manner as in Example 1.
As a result of accelerated weathering test using V test equipment, 35
After 0 hours, the gloss decreased significantly and many cracks occurred.

Comparative Example 3 100 parts of the monomers shown in Table 1 were polymerized in the same manner as in Example 1, with a Tg of -7°C, a valence of 08 of 151 (35% by weight of acrylic monomer containing hydroxyl groups), and a number average molecular weight of 100 parts. 1q of 19500 acrylic copolymer was obtained.

A paint was then prepared using the pigment paste and paint formulation of Comparative Example 3, and a painted foam was obtained in the same manner as in Example 1.

The painted foam thus prepared was treated with QU in the same manner as in Example 1.
As a result of accelerated weathering test using V test equipment, 15
Even after 00 hours, the decrease in gloss was small and no cracks were generated.

However, the foam painted with this paint became too stiff and would crack when bent.

Example 2 The paint prepared in Example 1 was applied to polypropylene foam [
"Torepefu" 3004PP (manufactured by Toshi ■) was coated in the same manner to obtain a coated foam.

The above painted foam and unpainted foam were sold in Ichihara City, Chiba Prefecture at 19
A 22-month outdoor exposure test was conducted from September 1975 to July 1977. As a result, the unpainted product had already deteriorated significantly after 4 months, and the surface collapsed into powder, but the coated foam did not develop any cracks even after 22 months, and its flexibility did not decrease.

Example 3 100 parts of the monomers shown in Table 1 were polymerized in the same manner as in Example 1 to obtain a Tg of 19°C, an OH value of 46, and a number average molecular weight of ff15.
000 acrylic copolymer.

Also, 294 parts of neopentyl glycol, 14 parts of adipic acid
After reacting 4 parts and 246 parts of isophthalic acid at 220'C for 10 hours, 202 parts of toluene was added to dilute the polyester with a number average molecular weight of 13,000 and a non-volatile content of 75%.
1 q of toluene solution.

Next, 100 parts of the above acrylic copolymer, 64 parts of polyester toluene solution, and 12 parts of Tuboran 4070 (manufactured by Nippon Polyurethane Industry Co., Ltd.) in polyester diol.
1 part, 36 parts of toluene were mixed, non-volatile content was 60% by weight, O
A 7-acrylic polyester mixture with an H value of 50 was obtained.

12.0 parts of the above acrylic-polyester mixture, 57.8 parts of titanium oxide, 80 parts of xylene/cellosolve acetate
Example 1
A pigment paste was obtained in a similar manner.

31.2 parts of the obtained pigment paste, 51.1 parts of acrylic-polyester mixture, 12.1 parts of polyisocyanate [Sumidur N-75 (manufactured by Sumitomo Bayer Urethane)].
1 part, and diluted with a mixed solvent of xylene/cellosolve acetate in a weight ratio of 80/20 while stirring to a viscosity suitable for spray painting to make a paint of 19.

The obtained paint was spray-painted on polyethylene foam ['Torepef' 3006 (Eastern ■)] and heated to 70'C.
The foam was heated for 30 minutes to obtain a coated foam with a dry coating film of 60 to 70 μm.

The coated foam thus prepared and the uncoated foam were subjected to an accelerated weathering test using a QUV device under the same conditions as in Example 1. As a result, cracks appeared on the entire surface of the uncoated foam after 130 hours. On the other hand, the painted foam did not generate any cracks even after 1500 hours.

Comparative Example 4 TC of Example 3] 19°C, OH value 46, number average molecule 15
A paint was prepared using the 000 acrylic copolymer using the pigment paste and paint formulation shown in Table 1, and a painted foam was obtained in the same manner as in Example 1.

Although good results were obtained in accelerated weathering tests using a QUVUV apparatus on the coated foam thus prepared, the coated foam became hard and easily cracked when bent.

Table 1 Acrylic copolymerized fabric and paint formulation <Effects of the invention> Compared to conventional polyolefin foams, which have been restricted from being used outdoors alone due to extremely poor weather resistance, the coating of the present invention The resulting polyolefin foam provides: 1. excellent weather resistance without degrading the properties of the foam;

2. Cosmetic properties, stain resistance, and surface strength are significantly improved.

It becomes possible to develop and expand outdoor applications such as

[Brief explanation of the drawing]

FIG. 1 is a graph showing changes in elongation retention when coated and uncoated polyethylene foams are exposed outdoors.

Claims (2)

[Claims] (1) Acrylic with a glass transition temperature of -20 to 5°C and a number average molecular weight of 3,000 to 30,000 as measured by gel permeation chromatography, which is copolymerized with 5 to 30% by weight of a hydroxyl group-containing acrylic monomer. System copolymer (I)
and a polyolefin foam coated with a coating composition containing a polyisocyanate compound. (2) A, copolymerized with 5 to 30% by weight of a hydroxyl group-containing acrylic monomer, with a glass transition temperature of -10 to 30°C and a number average molecular weight of 3,000 to 30,000 as measured by gel permeation chromatography. Acrylic copolymer (I
I) A coating composition containing 95 to 40% by weight of B, a composition obtained by mixing or copolymerizing 5 to 60% by weight of a compound (III) having two or more hydroxyl groups, and C, a polyisocyanate compound. Polyolefin foam coated with.